TY - JOUR AB - In 2022, Development launched its Pathway to Independence (PI) programme, aimed at supporting postdocs as they transition to their first independent position. In 2025, we welcome our third cohort of eight talented PI fellows. In this article, each fellow discusses their perspective on the future of their field and how their work will contribute to this exciting new era. AU - Ewe, C.K.* AU - Farnworth, M.S.* AU - Miller, A.* AU - Navajas Acedo, J.* AU - Oomen, M.E. AU - Paci, G.* AU - Widen, S.A.* AU - Yamada, T.* C1 - 75667 C2 - 58166 TI - Pathway to Independence: A forecast for the future of developmental biology. JO - Development VL - 152 IS - 19 PY - 2025 SN - 0950-1991 ER - TY - JOUR AB - In eukaryotic cells, the genetic material is organized into chromatin, which consists mainly of DNA, histones and chromatin-associated proteins. An important regulator of chromatin structure and function are histone post-translational modifications, which can shape gene expression patterns and control the epigenetic landscape. Here, we summarize the role of some key histone modifications in animal development, with a focus on the two best-studied types of histone modifications: lysine methylation and acylations, specifically, acetylation. AU - Liu, Y.-H. AU - Schneider, R. C1 - 74925 C2 - 57745 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Histone modifications in development. JO - Development VL - 152 IS - 12 PB - Company Biologists Ltd PY - 2025 SN - 0950-1991 ER - TY - JOUR AU - Oomen, M.E. C1 - 75529 C2 - 58032 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Pathway to Independence-an interview with Marlies Oomen. JO - Development VL - 152 IS - 16 PB - Company Biologists Ltd PY - 2025 SN - 0950-1991 ER - TY - JOUR AB - Collective cell rotations are widely used during animal organogenesis. Theoretical and in vitro studies have conceptualized rotating cells as identical rigid-point objects that stochastically break symmetry to move monotonously and perpetually within an inert environment. However, it is unclear whether this notion can be extrapolated to a natural context, where rotations are ephemeral and heterogeneous cellular cohorts interact with an active epithelium. In zebrafish neuromasts, nascent sibling hair cells invert positions by rotating ≤180° around their geometric center after acquiring different identities via Notch1a-mediated asymmetric repression of Emx2. Here, we show that this multicellular rotation is a three-phasic movement that progresses via coherent homotypic coupling and heterotypic junction remodeling. We found no correlation between rotations and epithelium-wide cellular flow or anisotropic resistive forces. Moreover, the Notch/Emx2 status of the cell dyad does not determine asymmetric interactions with the surrounding epithelium. Aided by computer modeling, we suggest that initial stochastic inhomogeneities generate a metastable state that poises cells to move and spontaneous intercellular coordination of the resulting instabilities enables persistently directional rotations, whereas Notch1a-determined symmetry breaking buffers rotational noise. AU - Kozak, E.L. AU - Miranda-Rodríguez, J.R. AU - Borges, A. AU - Dierkes, K.* AU - Mineo, A.* AU - Pinto-Teixeira, F.* AU - Viader Llargues, O. AU - Solon, J.* AU - Chara, O.* AU - López-Schier, H. C1 - 67700 C2 - 54007 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Quantitative videomicroscopy reveals latent control of cell-pair rotations in vivo. JO - Development VL - 150 IS - 9 PB - Company Biologists Ltd PY - 2023 SN - 0950-1991 ER - TY - JOUR AB - A powerful feature of single-cell genomics is the possibility of identifying cell types from their molecular profiles. In particular, identifying novel rare cell types and their marker genes is a key potential of single-cell RNA sequencing. Standard clustering approaches perform well in identifying relatively abundant cell types, but tend to miss rarer cell types. Here, we have developed CIARA (Cluster Independent Algorithm for the identification of markers of RAre cell types), a cluster-independent computational tool designed to select genes that are likely to be markers of rare cell types. Genes selected by CIARA are subsequently integrated with common clustering algorithms to single out groups of rare cell types. CIARA outperforms existing methods for rare cell type detection, and we use it to find previously uncharacterized rare populations of cells in a human gastrula and among mouse embryonic stem cells treated with retinoic acid. Moreover, CIARA can be applied more generally to any type of single-cell omic data, thus allowing the identification of rare cells across multiple data modalities. We provide implementations of CIARA in user-friendly packages available in R and Python. AU - Lubatti, G. AU - Stock, M. AU - Iturbide Martinez De Albeniz, A. AU - Ruiz Tejada Segura, M.L. AU - Riepl, M. AU - Tyser, R.C.V.* AU - Danese, A.* AU - Colomé-Tatché, M. AU - Theis, F.J. AU - Srinivas, S.* AU - Torres-Padilla, M.E. AU - Scialdone, A. C1 - 67836 C2 - 54314 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - CIARA: A cluster-independent algorithm for identifying markers of rare cell types from single-cell sequencing data. JO - Development VL - 150 IS - 11 PB - Company Biologists Ltd PY - 2023 SN - 0950-1991 ER - TY - JOUR AB - Organoids have become one of the fastest progressing and applied models in biological and medical research, and various organoids have now been developed for most of the organs of the body. Here, we review the methods developed to generate pancreas organoids in vitro from embryonic, fetal and adult cells, as well as pluripotent stem cells. We discuss how these systems have been used to learn new aspects of pancreas development, regeneration and disease, as well as their limitations and potential for future discoveries. AU - Grapin-Botton, A. AU - Kim, Y.H.* C1 - 66586 C2 - 53220 TI - Pancreas organoid models of development and regeneration. JO - Development VL - 149 IS - 20 PY - 2022 SN - 0950-1991 ER - TY - JOUR AU - Scialdone, A. AU - Rivron, N.* C1 - 66933 C2 - 53354 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - In preprints: Improving and interrogating embryo models. JO - Development VL - 149 IS - 23 PB - Company Biologists Ltd PY - 2022 SN - 0950-1991 ER - TY - JOUR AB - Regeneration-competent species possess the ability to reverse the progression of severe diseases by restoring the function of the damaged tissue. However, the cellular dynamics underlying this capability remain unexplored. Here, we have used single-cell transcriptomics to map de novo β-cell regeneration during induction and recovery from diabetes in zebrafish. We show that the zebrafish has evolved two distinct types of somatostatin-producing δ-cells, which we term δ1- and δ2-cells. Moreover, we characterize a small population of glucose-responsive islet cells, which share the hormones and fate-determinants of both β- and δ1-cells. The transcriptomic analysis of β-cell regeneration reveals that β/δ hybrid cells provide a prominent source of insulin expression during diabetes recovery. Using in vivo calcium imaging and cell tracking, we further show that the hybrid cells form de novo and acquire glucose-responsiveness in the course of regeneration. The overexpression of dkk3, a gene enriched in hybrid cells, increases their formation in the absence of β-cell injury. Finally, interspecies comparison shows that plastic δ1-cells are partially related to PP cells in the human pancreas. Our work provides an atlas of β-cell regeneration and indicates that the rapid formation of glucose-responsive hybrid cells contributes to the resolution of diabetes in zebrafish. AU - Singh, S.P.* AU - Chawla, P.* AU - Hnatiuk, A.* AU - Kamel, M.* AU - Silva, L.D.* AU - Spanjaard, B.* AU - Eski, S.E.* AU - Janjuha, S.* AU - Olivares-Chauvet, P.* AU - Kayisoglu, O.* AU - Rost, F.* AU - Bläsche, J.* AU - Kränkel, A.* AU - Petzold, A.* AU - Kurth, T.* AU - Reinhardt, S.* AU - Junker, J.P.* AU - Ninov, N. C1 - 64262 C2 - 52162 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - A single-cell atlas of de novo β-cell regeneration reveals the contribution of hybrid β/δ-cells to diabetes recovery in zebrafish. JO - Development VL - 149 IS - 2 PB - Company Biologists Ltd PY - 2022 SN - 0950-1991 ER - TY - JOUR AB - Cilia are complex cellular protrusions consisting of hundreds of proteins. Defects in ciliary structure and function, many of which have not been characterised molecularly, cause ciliopathies: a heterogeneous group of human syndromes. Here, we report on the FOXJ1 target gene Cfap206, orthologues of which so far have only been studied in Chlamydomonas and Tetrahymena In mouse and Xenopus, Cfap206 was co-expressed with and dependent on Foxj1 CFAP206 protein localised to the basal body and to the axoneme of motile cilia. In Xenopus crispant larvae, the ciliary beat frequency of skin multiciliated cells was enhanced and bead transport across the epidermal mucociliary epithelium was reduced. Likewise, Cfap206 knockout mice revealed ciliary phenotypes. Electron tomography of immotile knockout mouse sperm flagella indicated a role in radial spoke formation reminiscent of FAP206 function in Tetrahymena Male infertility, hydrocephalus and impaired mucociliary clearance of the airways in the absence of laterality defects in Cfap206 mutant mice suggests that Cfap206 may represent a candidate for the subgroup of human primary ciliary dyskinesias caused by radial spoke defects. AU - Beckers, A.* AU - Adis, C.* AU - Schuster-Gossler, K.* AU - Tveriakhina, L.* AU - Ott, T.* AU - Fuhl, F.* AU - Hegermann, J.* AU - Boldt, K.* AU - Serth, K.* AU - Rachev, E.* AU - Alten, L.* AU - Kremmer, E. AU - Ueffing, M.* AU - Blum, M.* AU - Gossler, A.* C1 - 59450 C2 - 48826 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - The FOXJ1 target Cfap206 is required for sperm motility, mucociliary clearance of the airways and brain development. JO - Development VL - 147 IS - 21 PB - Company Biologists Ltd PY - 2020 SN - 0950-1991 ER - TY - JOUR AB - Currently, two main cell culture models predominate pluripotent stem cell research: embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Thanks to their ability to contribute to and form all tissues within the body, ESCs and iPSCs have proven invaluable in understanding pluripotent states, early embryonic development and cell differentiation, as well as in devising strategies for regenerative medicine. Comparatively little is known about totipotency - a cellular state with greater developmental potential. In mice, only the zygote and the blastomeres of the 2-cell-stage embryo are truly totipotent, as they alone can develop to form the embryo and all of its supportive extra-embryonic tissues. However, the discovery of a rare subpopulation of cells in murine ESC cultures, possessing features of 2-cell embryo blastomeres and expanded cell fate potential, has provided a biochemically tractable model to enable the in vitro study of totipotency. Here, we summarize current known features of these 2-cell-like cells (2CLCs) in an effort to provide a reference for the community, and to clarify what we know about their identity so far. AU - Genet, M.* AU - Torres-Padilla, M.E. C1 - 59968 C2 - 49148 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - The molecular and cellular features of 2-cell-like cells: a reference guide. JO - Development VL - 147 IS - 16 PB - Company Biologists Ltd PY - 2020 SN - 0950-1991 ER - TY - JOUR AB - Deciphering mechanisms of endocrine cell induction, specification and lineage allocation in vivo will provide valuable insights into how the islets of Langerhans are generated. Currently, it is ill defined how endocrine progenitors segregate into different endocrine subtypes during development. Here, we generated a novel neurogenin 3 (Ngn3)-Venus fusion (NVF) reporter mouse line, that closely mirrors the transient endogenous Ngn3 protein expression. To define an in vivo roadmap of endocrinogenesis, we performed single cell RNA sequencing of 36,351 pancreatic epithelial and NVF+ cells during secondary transition. This allowed Ngn3(low) endocrine progenitors, Ngn3(high) endocrine precursors, Fev(+) endocrine lineage and hormone(+) endocrine subtypes to be distinguished and time-resolved, and molecular programs during the step-wise lineage restriction steps to be delineated. Strikingly, we identified 58 novel signature genes that show the same transient expression dynamics as Ngn3 in the 7260 profiled Ngn3-expressing cells. The differential expression of these genes in endocrine precursors associated with their cell-fate allocation towards distinct endocrine cell types. Thus, the generation of an accurately regulated NVF reporter allowed us to temporally resolve endocrine lineage development to provide a fine-grained single cell molecular profile of endocrinogenesis in vivo. AU - Bastidas-Ponce, A. AU - Tritschler, S. AU - Dony, L. AU - Scheibner, K. AU - Tarquis-Medina, M. AU - Salinno, C. AU - Schirge, S. AU - Burtscher, I. AU - Böttcher, A. AU - Theis, F.J. AU - Lickert, H. AU - Bakhti, M. C1 - 56211 C2 - 46900 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Comprehensive single cell mRNA profiling reveals a detailed roadmap for pancreatic endocrinogenesis. JO - Development VL - 146 IS - 12 PB - Company Biologists Ltd PY - 2019 SN - 0950-1991 ER - TY - JOUR AU - Bruneau, B.G.* AU - Koseki, H.* AU - Strome, S.* AU - Torres-Padilla, M.E. C1 - 57126 C2 - 47548 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Chromatin and epigenetics in development: A Special Issue. JO - Development VL - 146 IS - 19 PB - Company Biologists Ltd PY - 2019 SN - 0950-1991 ER - TY - JOUR AB - Single cell genomics has become a popular approach to uncover the cellular heterogeneity of progenitor and terminally differentiated cell types with great precision. This approach can also delineate lineage hierarchies and identify molecular programmes of cell-fate acquisition and segregation. Nowadays, tens of thousands of cells are routinely sequenced in single cell-based methods and even more are expected to be analysed in the future. However, interpretation of the resulting data is challenging and requires computational models at multiple levels of abstraction. In contrast to other applications of single cell sequencing, where clustering approaches dominate, developmental systems are generally modelled using continuous structures, trajectories and trees. These trajectory models carry the promise of elucidating mechanisms of development, disease and stimulation response at very high molecular resolution. However, their reliable analysis and biological interpretation requires an understanding of their underlying assumptions and limitations. Here, we review the basic concepts of such computational approaches and discuss the characteristics of developmental processes that can be learnt from trajectory models. AU - Tritschler, S. AU - Büttner, M. AU - Fischer, D.S. AU - Lange, M. AU - Bergen, V. AU - Lickert, H. AU - Theis, F.J. C1 - 56417 C2 - 47069 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Concepts and limitations for learning developmental trajectories from single cell genomics. JO - Development VL - 146 IS - 12 PB - Company Biologists Ltd PY - 2019 SN - 0950-1991 ER - TY - JOUR AB - The control of all our motor outputs requires constant monitoring by proprioceptive sensory neurons (PSNs) that convey continuous muscle sensory inputs to the spinal motor network. Yet the molecular programs that control the establishment of this sensorimotor circuit remain largely unknown. The transcription factor RUNX3 is essential for the early steps of PSNs differentiation, making it difficult to study its role during later aspects of PSNs specification. Here, we conditionally inactivate Runx3 in PSNs after peripheral innervation and identify that RUNX3 is necessary for maintenance of cell identity of only a subgroup of PSNs, without discernable cell death. RUNX3 also controls the sensorimotor connection between PSNs and motor neurons at limb level, with muscle-by-muscle variable sensitivities to the loss of Runx3 that correlate with levels of RUNX3 in PSNs. Finally, we find that muscles and neurotrophin 3 signaling are necessary for maintenance of RUNX3 expression in PSNs. Hence, a transcriptional regulator that is crucial for specifying a generic PSN type identity after neurogenesis is later regulated by target muscle-derived signals to contribute to the specialized aspects of the sensorimotor connection selectivity. AU - Wang, Y.* AU - Wu, H.* AU - Zelenin, P.* AU - Fontanet, P.* AU - Wanderoy, S.* AU - Petitpré, C.* AU - Comai, G.* AU - Bellardita, C.* AU - Xue-Franzén, Y.* AU - Huettl, R.E. AU - Huber, A.B. AU - Tajbakhsh, S.* AU - Kiehn, O.* AU - Ernfors, P.* AU - Deliagina, T.G.* AU - Lallemend, F.* AU - Hadjab, S.* C1 - 57243 C2 - 47638 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Muscle-selective RUNX3 dependence of sensorimotor circuit development. JO - Development VL - 146 IS - 20 PB - Company Biologists Ltd PY - 2019 SN - 0950-1991 ER - TY - JOUR AB - Mutations in Hes1, a target gene of the Notch signalling pathway, lead to ectopic pancreas by a poorly described mechanism. Here, we use genetic inactivation of Hes1 combined with lineage tracing and live imaging to reveal an endodermal requirement for Hes1, and show that ectopic pancreas tissue is derived from the dorsal pancreas primordium. RNA-seq analysis of sorted E10.5 Hes1(+/+) and Hes1(-/-) Pdx1-GFP(+) cells suggested that upregulation of endocrine lineage genes in Hes1(-/-) embryos was the major defect and, accordingly, early pancreas morphogenesis was normalized, and the ectopic pancreas phenotype suppressed, in Hes1(-/-)Neurog3(-/-) embryos. In Mib1 mutants, we found a near total depletion of dorsal progenitors, which was replaced by an anterior Gcg(+) extension. Together, our results demonstrate that aberrant morphogenesis is the cause of ectopic pancreas and that a part of the endocrine differentiation program is mechanistically involved in the dysgenesis. Our results suggest that the ratio of endocrine lineage to progenitor cells is important for morphogenesis and that a strong endocrinogenic phenotype without complete progenitor depletion, as seen in Hes1 mutants, provokes an extreme dysgenesis that causes ectopic pancreas. AU - Jørgensen, M.C.* AU - de Lichtenberg, K.H.* AU - Collin, C.A.* AU - Klinck, R.* AU - Ekberg, J.H.* AU - Engelstoft, M.S.* AU - Lickert, H. AU - Serup, P.* C1 - 54120 C2 - 45358 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Neurog3-dependent pancreas dysgenesis causes ectopic pancreas in Hes1 mutant mice. JO - Development VL - 145 IS - 7 PB - Company Biologists Ltd PY - 2018 SN - 0950-1991 ER - TY - JOUR AB - The trans-Golgi-network (TGN) has essential housekeeping functions in secretion, endocytosis and protein sorting, but also more specialized functions in plant development. How the robustness of basal TGN function is ensured while specialized functions are differentially regulated is poorly understood. Here, we investigate two key regulators of TGN structure and function, ECHIDNA and the Transport Protein Particle II (TRAPPII) tethering complex. An analysis of physical, network and genetic interactions suggests that two network communities are implicated in TGN function and that ECHIDNA and TRAPPII belong to distinct yet overlapping pathways. Whereas ECHIDNA and TRAPPII colocalized at the TGN in interphase cells, their localization diverged in dividing cells. Moreover, ECHIDNA and TRAPPII localization patterns were mutually independent. TGN structure, endocytosis and sorting decisions were differentially impacted in echidna and trappii mutants. Our analyses point to a partitioning of specialized TGN functions, with ECHIDNA being required for cell elongation and TRAPPII for cytokinesis. Two independent pathways able to compensate for each other might contribute to the robustness of TGN housekeeping functions and to the responsiveness and fine tuning of its specialized functions. AU - Ravikumar, R.* AU - Kalbfuß, N.* AU - Gendre, D.* AU - Steiner, A.* AU - Altmann, M. AU - Altmann, S. AU - Rybak, K.* AU - Edelmann, H.* AU - Stephan, F.* AU - Lampe, M.* AU - Facher, E.* AU - Wanner, G.* AU - Falter-Braun, P. AU - Bhalerao, R.P.* AU - Assaad, F.F.* C1 - 54704 C2 - 45774 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Independent yet overlapping pathways ensure the robustness and responsiveness of trans-Golgi network functions in Arabidopsis. JO - Development VL - 145 IS - 21 PB - Company Biologists Ltd PY - 2018 SN - 0950-1991 ER - TY - JOUR AB - The pancreas is an endoderm-derived glandular organ that participates in the regulation of systemic glucose metabolism and food digestion through the function of its endocrine and exocrine compartments, respectively. While intensive research has explored the signaling pathways and transcriptional programs that govern pancreas development, much remains to be discovered regarding the cellular processes that orchestrate pancreas morphogenesis. Here, we discuss the developmental mechanisms and principles that are known to underlie pancreas development, from induction and lineage formation to morphogenesis and organogenesis. Elucidating such principles will help to identify novel candidate disease genes and unravel the pathogenesis of pancreas-related diseases, such as diabetes, pancreatitis and cancer. AU - Bastidas-Ponce, A. AU - Scheibner, K. AU - Lickert, H. AU - Bakhti, M. C1 - 51753 C2 - 43434 CY - Cambridge SP - 2873-2888 TI - Cellular and molecular mechanisms coordinating pancreas development. JO - Development VL - 144 IS - 16 PB - Company Of Biologists Ltd PY - 2017 SN - 0950-1991 ER - TY - JOUR AB - In early April 2017, over 130 delegates met in Munich, Germany, to discuss the latest research in the development and reprogramming of cells of the nervous system. The conference, which was organised by Abcam and entitled ‘Programming and Reprogramming the Brain’, was a great success, and provided an excellent snapshot of the current state of the field, and what the challenges are for the future. This Meeting Review provides a summary of the talks presented and the major themes that emerged from the conference. AU - Götz, M. AU - Jarriault, S.* C1 - 51712 C2 - 43428 CY - Cambridge SP - 2714-2718 TI - Programming and reprogramming the brain: A meeting of minds in neural fate. JO - Development VL - 144 IS - 15 PB - Company Of Biologists Ltd PY - 2017 SN - 0950-1991 ER - TY - JOUR AB - The low-density lipoprotein receptor-related protein 4 (LRP4) is essential in muscle fibers for the establishment of the neuromuscular junction. Here, we show that LRP4 is also expressed by embryonic cortical and hippocampal neurons, and that downregulation of LRP4 in these neurons causes a reduction in density of synapses and number of primary dendrites. Accordingly, overexpression of LRP4 in cultured neurons had the opposite effect inducing more but shorter primary dendrites with an increased number of spines. Transsynaptic tracing mediated by rabies virus revealed a reduced number of neurons presynaptic to the cortical neurons in which LRP4 was knocked down. Moreover, neuron-specific knockdown of LRP4 by in utero electroporation of LRP4 miRNA in vivo also resulted in neurons with fewer primary dendrites and a lower density of spines in the developing cortex and hippocampus. Collectively, our results demonstrate an essential and novel role of neuronal LRP4 in dendritic development and synaptogenesis in the CNS. AU - Karakatsani, A.* AU - Marichal, N.* AU - Urban, S.* AU - Kalamakis, G.* AU - Ghanem, A.* AU - Schick, A.J.* AU - Zhang, Y.* AU - Conzelmann, K.* AU - Rüegg, M.A.* AU - Berninger, B.* AU - de Almodovar, C.R.* AU - Gascón, S. AU - Kroeger, S.* C1 - 52665 C2 - 44215 CY - Cambridge SP - 4604-4615 TI - Neuronal LRP4 regulates synapse formation in the developing CNS. JO - Development VL - 144 IS - 24 PB - Company Of Biologists Ltd PY - 2017 SN - 0950-1991 ER - TY - JOUR AB - During corticogenesis, distinct classes of neurons are born from progenitor cells located in the ventricular and subventricular zones, from where they migrate towards the pial surface to assemble into highly organized layer-specific circuits. However, the precise and coordinated transcriptional network activity defining neuronal identity is still not understood. Here, we show that genetic depletion of the basic helix-loop-helix (bHLH) transcription factor E2A splice variant E47 increased the number of Tbr1-positive deep layer and Satb2-positive upper layer neurons at E14.5, while depletion of the alternatively spliced E12 variant did not affect layer-specific neurogenesis. While ChIP-Seq identified a big overlap for E12- and E47-specific binding sites in embryonic NSCs, including sites at the cyclin-dependent kinase inhibitor (CDKI) Cdkn1c gene locus, RNA-Seq revealed a unique transcriptional regulation by each splice variant. E47 activated the expression of the CDKI Cdkn1c through binding to a distal enhancer. Finally, overexpression of E47 in embryonic NSCs in vitro impaired neurite outgrowth and E47 overexpression in vivo by in utero electroporation disturbed proper layer-specific neurogenesis and upregulated p57(KIP2) expression. Overall, this study identified E2A target genes in embryonic NSCs and demonstrates that E47 regulates neuronal differentiation via p57(KIP2). AU - Pfurr, S.* AU - Chu, Y.H.* AU - Bohrer, C.* AU - Greulich, F. AU - Beattie, R.* AU - Mammadzada, K.* AU - Hils, M.* AU - Arnold, S.J.* AU - Taylor, V.* AU - Schachtrup, K.* AU - Uhlenhaut, N.H. AU - Schachtrup, C.* C1 - 51964 C2 - 43625 CY - Cambridge SP - 3917-3931 TI - The E2A splice variant E47 regulates the differentiation of projection neurons via p57(KIP2) during cortical development. JO - Development VL - 144 IS - 21 PB - Company Of Biologists Ltd PY - 2017 SN - 0950-1991 ER - TY - JOUR AB - An international cohort of over 300 stem cell biologists came together in Heidelberg, Germany in May 2017 as delegates of the 'Advances in Stem Cells and Regenerative Medicine' conference run through the European Molecular Biology Organization. This Meeting Review highlights the novel insights into stem cell regulation, new technologies aiding in discovery and exciting breakthroughs in the field of regenerative medicine that emerged from the meeting. AU - Twigger, A.-J. AU - Scheel, C. C1 - 51782 C2 - 43519 CY - Cambridge SP - 3007-3011 TI - Advances in stem cells and regenerative medicine: Single-cell dynamics, new models and translational perspectives. JO - Development VL - 144 IS - 17 PB - Company Of Biologists Ltd PY - 2017 SN - 0950-1991 ER - TY - JOUR AB - Mesodiencephalic dopaminergic (mdDA) neurons are located in the ventral mesencephalon and caudal diencephalon of all tetrapod species studied so far. They are the most prominent DA neuronal population and are implicated in control and modulation of motor, cognitive and rewarding/affective behaviors. Their degeneration or dysfunction is intimately linked to several neurological and neuropsychiatric human diseases. To gain further insights into their generation, we studied spatiotemporal expression patterns and epistatic interactions in chick embryos of selected marker genes and signaling pathways associated with mdDA neuron development in mouse. We detected striking differences in the expression patterns of the chick orthologs of the mouse mdDA marker genes Pitx3 and Aldh1a1, which suggests important differences between the species in the generation/generating of these cells. We also discovered that the Sonic hedgehog signaling pathway is both, necessary and sufficient for the induction of ectopic PITX3 expression in chick mesencephalon downstream of WNT9A induced LMX1a transcription. These aspects of early chicken development resemble the ontogeny of zebrafish diencephalic DA neuronal populations, and suggest a divergence between birds and mammals during evolution. AU - Klafke, R. AU - Prem Anand, A.A.* AU - Wurst, W. AU - Prakash, N. AU - Wizenmann, A.* C1 - 47677 C2 - 39714 CY - Cambridge SP - 691-702 TI - Differences in the spatiotemporal expression and epistatic gene regulation of the mesodiencephalic dopaminergic precursor marker PITX3 during chicken and mouse development. JO - Development VL - 143 IS - 4 PB - Company Of Biologists Ltd PY - 2016 SN - 0950-1991 ER - TY - JOUR AB - The key signalling pathways and transcriptional programmes that instruct neuronal diversity during development have largely been identified. In this Review, we discuss how this knowledge has been used to successfully reprogramme various cell types into an amazing array of distinct types of functional neurons. We further discuss the extent to which direct neuronal reprogramming recapitulates embryonic development, and examine the particular barriers to reprogramming that may exist given a cell's unique developmental history. We conclude with a recently proposed model for cell specification called the 'Cook Islands' model, and consider whether it is a fitting model for cell specification based on recent results from the direct reprogramming field. AU - Masserdotti, G. AU - Gascón, S. AU - Götz, M. C1 - 49134 C2 - 41625 CY - Cambridge SP - 2494-2510 TI - Direct neuronal reprogramming: Learning from and for development. JO - Development VL - 143 IS - 14 PB - Company Of Biologists Ltd PY - 2016 SN - 0950-1991 ER - TY - JOUR AB - The H3K9me3-specific histone methyltransferase Setdb1 impacts on transcriptional regulation by repressing both developmental genes and retrotransposons. How impaired retrotransposon silencing may lead to developmental phenotypes is currently unclear. Here we show that loss of Setdb1 in pro-B cells completely abrogates B cell development. In pro-B cells, Setdb1 is dispensable for silencing of lineage-inappropriate developmental genes. Instead, we detect strong derepression of endogenous Murine Leukemia Virus (MLV) copies. This activation coincides with an unusual change in chromatin structure with only partial loss of H3K9me3 and unchanged DNA methylation, but strongly increased H3K4me3. Production of MLV proteins leads to activation of the unfolded protein response pathway and apoptosis. Thus, our data demonstrate that B cell development critically depends on the proper repression of retrotransposon sequences through Setdb1. AU - Pasquarella, A.* AU - Ebert, A.* AU - de Almeida, G.P.* AU - Hinterberger, M.* AU - Kazerani, M.* AU - Nuber, A.* AU - Ellwart, J.W. AU - Klein, L.* AU - Busslinger, M.* AU - Schotta, G.* C1 - 48193 C2 - 41053 CY - Cambridge SP - 1788-1799 TI - Retrotransposon derepression leads to activation of the unfolded protein response and apoptosis in pro-B cells. JO - Development VL - 143 IS - 10 PB - Company Of Biologists Ltd PY - 2016 SN - 0950-1991 ER - TY - JOUR AB - The zebrafish is a well-established model organism to study in vivo mechanisms of cell communication, differentiation and function. Existing cell ablation methods are either invasive thereby creating additional tissue damage and potential infection sites, or they rely on the cellular expression of prokaryotic enzymes and the use of antibiotic drugs as cell-death-inducing compounds. We have recently established a novel inducible genetic cell ablation system that is based on Tamoxifen-inducible Caspase8-activity, thereby exploiting mechanisms of cell death intrinsic to most cell types. Here we prove its suitability in vivo by the ablation of cerebellar Purkinje cells (PCs) in transgenic zebrafish, which coexpress the inducible Caspase and a fluorescent reporter to monitor ablation processes. Incubation of larvae in Tamoxifen for 8 hrs activated endogenous Caspase3 and cell death, while incubation for 16 hrs led to the nearly complete loss of PCs by apoptosis. Using live confocal imaging, we observed synchronous cell death autonomous to the PC population and phagocytosing microglia in the cerebellum, reminiscent of developmental apoptosis in the forebrain. Thus, induction of Apoptosis Through Targeted Activation of Caspase by Tamoxifen (ATTAC(TM)) further expands the repertoire of genetic tools in zebrafish for conditional interrogation of cellular functions. AU - Weber, T. AU - Namikawa, K.* AU - Winter, B.* AU - Müller-Brown, K.* AU - Kühn, R. AU - Wurst, W. AU - Köster, R.W.* C1 - 49715 C2 - 40892 CY - Cambridge SP - 4279-4287 TI - Caspase-mediated apoptosis induction in zebrafish cerebellar Purkinje neurons. JO - Development VL - 143 IS - 22 PB - Company Of Biologists Ltd PY - 2016 SN - 0950-1991 ER - TY - JOUR AB - Motile cilia move extracellular fluids or mediate cellular motility. Their function is essential for embryonic development, adult tissue homeostasis and reproduction throughout vertebrates. FOXJ1 is a key transcription factor for the formation of motile cilia but its downstream genetic programme is only partially understood. Here, we characterise a novel FOXJ1 target, Cfap157, that is specifically expressed in motile ciliated tissues in mouse and Xenopus in a FOXJ1-dependent manner. CFAP157 protein localises to basal bodies and interacts with tubulin and the centrosomal protein CEP350. Cfap157 knockout mice appear normal but homozygous males are infertile. Spermatozoa display impaired motility and a novel phenotype: Cfap157-deficient sperm exhibit axonemal loops, supernumerary axonemal profiles with ectopic accessory structures, excess cytoplasm and clustered mitochondria in the midpiece regions, and defective axonemes along the flagella. Our study thus demonstrates an essential sperm-specific function for CFAP157 and suggests that this novel FOXJ1 effector is part of a mechanism that acts during spermiogenesis to suppress the formation of supernumerary axonemes and ensures a correct ultrastructure. AU - Weidemann, M.* AU - Schuster-Gossler, K.* AU - Stauber, M.* AU - Wrede, C.* AU - Hegermann, J.* AU - Ott, T.* AU - Boldt, K.* AU - Beyer, T.* AU - Serth, K.* AU - Kremmer, E. AU - Blum, M.* AU - Ueffing, M.* AU - Gossler, A.* C1 - 50184 C2 - 42065 CY - Cambridge SP - 4736-4748 TI - CFAP157 is a murine downstream effector of FOXJ1 that is specifically required for flagellum morphogenesis and sperm motility. JO - Development VL - 143 IS - 24 PB - Company Of Biologists Ltd PY - 2016 SN - 0950-1991 ER - TY - JOUR AB - Current understanding infers a neural crest origin of thyroid C cells, the major source of calcitonin in mammals and ancestors to neuroendocrine thyroid tumors. The concept is primarily based on investigations in quail–chick chimeras involving fate mapping of neural crest cells to the ultimobranchial glands that regulate Ca2+ homeostasis in birds, reptiles, amphibians and fishes, but whether mammalian C cell development involves a homologous ontogenetic trajectory has not been experimentally verified. With lineage tracing, we now provide direct evidence that Sox17+ anterior endoderm is the only source of differentiated C cells and their progenitors in mice. Like many gut endoderm derivatives, embryonic C cells were found to coexpress pioneer factors forkhead box (Fox) a1 and Foxa2 before neuroendocrine differentiation takes place. In the ultimobranchial body epithelium emerging from pharyngeal pouch endoderm in early organogenesis, differential Foxa1/Foxa2 expression distinguished two spatially separated pools of C cell precursors with different growth properties. A similar expression pattern was recapitulated in medullary thyroid carcinoma cells in vivo, consistent with a growth-promoting role of Foxa1. In contrast to embryonic precursor cells, C cell-derived tumor cells invading the stromal compartment downregulated Foxa2, foregoing epithelial-to-mesenchymal transition designated by loss of E-cadherin;bothFoxa2 andE-cadherinwere re-expressed atmetastatic sites. These findings revise mammalian C cell ontogeny, expand the neuroendocrine repertoire of endoderm and redefine the boundaries of neural crest diversification.The data further underpin distinct functions of Foxa1 and Foxa2 in both embryonic and tumor development. AU - Johansson, E.* AU - Andersson, L.B.* AU - Örnros, J.* AU - Carlsson, T.* AU - Ingeson-Carlsson, C.* AU - Liang, S.* AU - Dahlberg, J.* AU - Jansson, S.A.* AU - Parrillo, L.* AU - Zoppoli, P.* AU - Barila, G.O.* AU - Altschuler, D.L.* AU - Padula, D. AU - Lickert, H. AU - Fagman, H.* AU - Nilsson, M.* C1 - 47143 C2 - 39131 SP - 3519-3528 TI - Revising the embryonic origin of thyroid C cells in mice and humans. JO - Development VL - 142 IS - 20 PY - 2015 SN - 0950-1991 ER - TY - JOUR AB - Multiciliated cells are abundant in the epithelial surface of different tissues, including cells lining the walls of the lateral ventricles in the brain and the airway epithelium. Their main role is to control fluid flow and defects in their differentiation are implicated in many human disorders, such as hydrocephalus, accompanied by defects in adult neurogenesis and mucociliary disorder in the airway system. Here we show that Mcidas, which is mutated in human mucociliary clearance disorder, and GemC1 (Gmnc or Lynkeas), previously implicated in cell cycle progression, are key regulators of multiciliated ependymal cell generation in the mouse brain. Overexpression and knockdown experiments show that Mcidas and GemC1 are sufficient and necessary for cell fate commitment and differentiation of radial glial cells to multiciliated ependymal cells. Furthermore, we show that GemC1 and Mcidas operate in hierarchical order, upstream of Foxj1 and c-Myb transcription factors, which are known regulators of ependymal cell generation, and that Notch signaling inhibits GemC1 and Mcidas function. Our results suggest that Mcidas and GemC1 are key players in the generation of multiciliated ependymal cells of the adult neurogenic niche. AU - Kyrousi, C.* AU - Arbi, M.* AU - Pilz, G.-A. AU - Pefani, D.E.* AU - Lalioti, M.E.* AU - Ninkovic, J. AU - Götz, M. AU - Lygerou, Z.* AU - Taraviras, S.* C1 - 47268 C2 - 39359 SP - 3661-3674 TI - Mcidas and GemC1 are key regulators for the generation of multiciliated ependymal cells in the adult neurogenic niche. JO - Development VL - 142 IS - 21 PY - 2015 SN - 0950-1991 ER - TY - JOUR AB - We present an organoid regeneration assay in which freshly isolated human mammary epithelial cells are cultured in adherent or floating collagen gels, corresponding to a rigid or compliant matrix environment. In both conditions, luminal progenitors form spheres, whereas basal cells generate branched ductal structures. In compliant but not rigid collagen gels, branching ducts form alveoli at their tips, express basal and luminal markers at correct positions, and display contractility, which is required for alveologenesis. Thereby, branched structures generated in compliant collagen gels resemble terminal ductal-lobular units (TDLUs), the functional units of the mammary gland. Using the membrane metallo-endopeptidase CD10 as a surface marker enriches for TDLU formation and reveals the presence of stromal cells within the CD49f(hi)/EpCAM(-) population. In summary, we describe a defined in vitro assay system to quantify cells with regenerative potential and systematically investigate their interaction with the physical environment at distinct steps of morphogenesis. AU - Linnemann, J. AU - Miura, H. AU - Meixner, L.K. AU - Irmler, M. AU - Kloos, U. AU - Hirschi, B. AU - Bartsch, H.S.* AU - Sass, S. AU - Beckers, J. AU - Theis, F.J. AU - Gabka, C.* AU - Sotlar, K.* AU - Scheel, C. C1 - 45191 C2 - 37252 SP - 3239-3251 TI - Quantification of regenerative potential in primary human mammary epithelial cells. JO - Development VL - 142 IS - 18 PY - 2015 SN - 0950-1991 ER - TY - JOUR AB - Microphthalmos is a rare congenital anomaly characterized by reduced eye size and visual deficits of variable degrees. Sporadic and hereditary microphthalmos has been associated to heterozygous mutations in genes fundamental for eye development. Yet, many cases are idiopathic or await the identification of molecular causes. Here we show that haploinsufficiency of Meis1, a transcription factor with an evolutionary conserved expression in the embryonic trunk, brain and sensory organs, including the eye, causes microphthalmic traits and visual impairment, in adult mice. By combining the analysis of Meis1 loss-of-function and conditional Meis1 functional rescue with ChIP-seq and RNA-seq approaches we show that, in contrast to Meis1 preferential association with Hox-Pbx binding sites in the trunk, Meis1 binds to Hox/Pbx-independent sites during optic cup development. In the eye primordium, Meis1 coordinates, in a dose-dependent manner, retinal proliferation and differentiation by regulating genes responsible for human microphthalmia and components the Notch signalling pathway. In addition, Meis1 is required for eye patterning by controlling a set of eye territory-specific transcription factors, so that in Meis1(-/-) embryos boundaries among the different eye territories are shifted or blurred. We thus propose that Meis1 is at the core of a genetic network implicated in eye patterning/microphthalmia, itself representing an additional candidate for syndromic cases of these ocular malformations. AU - Marcos, S.* AU - González-Lázaro, M.* AU - Beccari, L.* AU - Carramolino, L.* AU - Martin-Bermejo, M.J.* AU - Amarie, O.V. AU - Martín, D.M.* AU - Torroja, C.* AU - Bogdanović, O.* AU - Doohan, R.* AU - Puk, O. AU - Hrabě de Angelis, M. AU - Graw, J. AU - Gómez-Skarmeta, J.L.* AU - Casares, F.* AU - Torres, M.* AU - Bovolenta, P. C1 - 46549 C2 - 37637 SP - 3009-3020 TI - Meis1 coordinates a network of genes implicated in eye development and microphthalmia. JO - Development VL - 142 IS - 17 PY - 2015 SN - 0950-1991 ER - TY - JOUR AB - The maintenance and control of pluripotency is of great interest in stem cell biology. The dual specificity T-box/basic-helix-loop-helix-zipper transcription factor Mga is expressed in the pluripotent cells of the inner cell mass (ICM) and epiblast of the peri-implantation mouse embryo, but its function has not been investigated previously. Here, we use a loss-of-function allele and RNA knockdown to demonstrate that Mga depletion leads to the death of proliferating pluripotent ICM cells in vivo and in vitro, and the death of embryonic stem cells (ESCs) in vitro. Additionally, quiescent pluripotent cells lacking Mga are lost during embryonic diapause. Expression of Odc1, the rate-limiting enzyme in the conversion of ornithine into putrescine in the synthesis of polyamines, is reduced in Mga mutant cells, and the survival of mutant ICM cells as well as ESCs is rescued in culture by the addition of exogenous putrescine. These results suggest a mechanism whereby Mga influences pluripotent cell survival through regulation of the polyamine pool in pluripotent cells of the embryo, whether they are in a proliferative or quiescent state. AU - Washkowitz, A.J.* AU - Schall, C.* AU - Zhang, K.L.* AU - Wurst, W. AU - Floß, T. AU - Mager, J.* AU - Papaioannou, V.E.* C1 - 43042 C2 - 35961 CY - Cambridge SP - 31-40 TI - Mga is essential for the survival of pluripotent cells during peri-implantation development. JO - Development VL - 142 IS - 1 PB - Company Of Biologists Ltd PY - 2015 SN - 0950-1991 ER - TY - JOUR AB - During embryonic development, the rostral neuroectoderm is regionalized into broad areas that are subsequently subdivided into progenitor compartments with specialized identity and fate. These events are controlled by signals emitted by organizing centers and interpreted by target progenitors, which activate superimposing waves of intrinsic factors restricting their identity and fate. The transcription factor Otx2 plays a crucial role in mesencephalic development by positioning the midbrain-hindbrain boundary (MHB) and its organizing activity. Here, we investigated whether Otx2 is cell-autonomously required to control identity and fate of dorsal mesencephalic progenitors. With this aim, we have inactivated Otx2 in the Pax7(+) dorsal mesencephalic domain, previously named m1, without affecting MHB integrity. We found that the Pax7(+) m1 domain can be further subdivided into a dorsal Zic1(+) m1a and a ventral Zic1(-) m1b sub-domain. Loss of Otx2 in the m1a (Pax7(+) Zic1(+)) sub-domain impairs the identity and fate of progenitors, which undergo a full switch into a coordinated cerebellum differentiation program. By contrast, in the m1b sub-domain (Pax7(+) Zic1(-)) Otx2 is prevalently required for post-mitotic transition of mesencephalic GABAergic precursors. Moreover, genetic cell fate, BrdU cell labeling and Otx2 conditional inactivation experiments indicate that in Otx2 mutants all ectopic cerebellar cell types, including external granule cell layer (EGL) precursors, originate from the m1a progenitor sub-domain and that reprogramming of mesencephalic precursors into EGL or cerebellar GABAergic progenitors depends on temporal sensitivity to Otx2 ablation. Together, these findings indicate that Otx2 intrinsically controls different aspects of dorsal mesencephalic neurogenesis. In this context, Otx2 is cell-autonomously required in the m1a sub-domain to suppress cerebellar fate and promote mesencephalic differentiation independently of the MHB organizing activity. AU - di Giovannantonio, L.G.* AU - di Salvio, M.* AU - Omodei, D.* AU - Prakash, N. AU - Wurst, W. AU - Pierani, A.* AU - Acampora, D.* AU - Simeone, A.* C1 - 28866 C2 - 33552 SP - 377-388 TI - Otx2 cell-autonomously determines dorsal mesencephalon versus cerebellum fate independently of isthmic organizing activity. JO - Development VL - 141 IS - 2 PY - 2014 SN - 0950-1991 ER - TY - JOUR AB - Transcription factors (TFs) pattern developing tissues and determine cell fates; however, how spatio-temporal TF gradients are generated is ill defined. Here we show that miR-335 fine-tunes TF gradients in the endoderm and promotes mesendodermal lineage segregation. Initially, we identified miR-335 as a regulated intronic miRNA in differentiating embryonic stem cells (ESCs). miR-335 is encoded in the mesoderm-specific transcript (Mest) and targets the 3'-UTRs of the endoderm-determining TFs Foxa2 and Sox17. Mest and miR-335 are co-expressed and highly accumulate in the mesoderm, but are transiently expressed in endoderm progenitors. Overexpression of miR-335 does not affect initial mesendoderm induction, but blocks Foxa2- and Sox17-mediated endoderm differentiation in ESCs and ESC-derived embryos. Conversely, inhibition of miR-335 activity leads to increased Foxa2 and Sox17 protein accumulation and endoderm formation. Mathematical modeling predicts that transient miR-335 expression in endoderm progenitors shapes a TF gradient in the endoderm, which we confirm by functional studies in vivo. Taken together, our results suggest that miR-335 targets endoderm TFs for spatio-temporal gradient formation in the endoderm and to stabilize lineage decisions during mesendoderm formation. AU - Yang, D. AU - Lutter, D. AU - Burtscher, I. AU - Uetzmann, L. AU - Theis, F.J. AU - Lickert, H. C1 - 29059 C2 - 33611 CY - Cambridge SP - 514-525 TI - miR-335 promotes mesendodermal lineage segregation and shapes a transcription factor gradient in the endoderm. JO - Development VL - 141 IS - 3 PB - Company Of Biologists Ltd PY - 2014 SN - 0950-1991 ER - TY - JOUR AB - Meis homeodomain transcription factors control cell proliferation, cell fate specification and differentiation in development and disease. Previous studies have largely focused on Meis contribution to the development of non-neuronal tissues. By contrast, Meis function in the brain is not well understood. Here, we provide evidence for a dual role of the Meis family protein Meis2 in adult olfactory bulb (OB) neurogenesis. Meis2 is strongly expressed in neuroblasts of the subventricular zone (SVZ) and rostral migratory stream (RMS) and in some of the OB interneurons that are continuously replaced during adult life. Targeted manipulations with retroviral vectors expressing function-blocking forms or with small interfering RNAs demonstrated that Meis activity is cell-autonomously required for the acquisition of a general neuronal fate by SVZ-derived progenitors in vivo and in vitro. Additionally, Meis2 activity in the RMS is important for the generation of dopaminergic periglomerular neurons in the OB. Chromatin immunoprecipitation identified doublecortin and tyrosine hydroxylase as direct Meis targets in newly generated neurons and the OB, respectively. Furthermore, biochemical analyses revealed a previously unrecognized complex of Meis2 with Pax6 and Dlx2, two transcription factors involved in OB neurogenesis. The full pro-neurogenic activity of Pax6 in SVZ derived neural stem and progenitor cells requires the presence of Meis. Collectively, these results show that Meis2 cooperates with Pax6 in generic neurogenesis and dopaminergic fate specification in the adult SVZ-OB system. AU - Agoston, Z.* AU - Heine, P.* AU - Brill, M.S. AU - Grebbin, B.M.* AU - Hau, A.C.* AU - Kallenborn-Gerhardt, W.* AU - Schramm, J.* AU - Götz, M. AU - Schulte, D.* C1 - 28574 C2 - 33464 SP - 28-38 TI - Meis2 is a Pax6 co-factor in neurogenesis and dopaminergic periglomerular fate specification in the adult olfactory bulb. JO - Development VL - 141 IS - 1 PB - Company of Biologists PY - 2013 SN - 0950-1991 ER - TY - JOUR AB - Several signalling cascades are implicated in the formation and patterning of the three principal germ layers, but their precise temporal-spatial mode of action in progenitor populations remains undefined. We have used conditional gene deletion of mouse β-catenin in Sox17-positive embryonic and extra-embryonic endoderm as well as vascular endothelial progenitors to address the function of canonical Wnt signalling in cell lineage formation and patterning. Conditional mutants fail to form anterior brain structures and exhibit posterior body axis truncations, whereas initial blood vessel formation appears normal. Tetraploid rescue experiments reveal that lack of β-catenin in the anterior visceral endoderm results in defects in head organizer formation. Sox17 lineage tracing in the definitive endoderm (DE) shows a cell-autonomous requirement for β-catenin in midgut and hindgut formation. Surprisingly, wild-type posterior visceral endoderm (PVE) in midgut- and hindgut-deficient tetraploid chimera rescues the posterior body axis truncation, indicating that the PVE is important for tail organizer formation. Upon loss of β-catenin in the visceral endoderm and DE lineages, but not in the vascular endothelial lineage, Sox17 expression is not maintained, suggesting downstream regulation by canonical Wnt signalling. Strikingly, Tcf4/β-catenin transactivation complexes accumulated on Sox17 cis-regulatory elements specifically upon endoderm induction in an embryonic stem cell differentiation system. Together, these results indicate that the Wnt/β-catenin signalling pathway regulates Sox17 expression for visceral endoderm pattering and DE formation and provide the first functional evidence that the PVE is necessary for gastrula organizer gene induction and posterior axis development. AU - Engert, S. AU - Burtscher, I. AU - Liao, W.P. AU - Dulev, S.* AU - Schotta, G.* AU - Lickert, H. C1 - 26048 C2 - 32043 SP - 3128-3138 TI - Wnt/β-catenin signalling regulates Sox17 expression and is essential for organizer and endoderm formation in the mouse. JO - Development VL - 140 IS - 15 PB - Company of Biologists Ltd. PY - 2013 SN - 0950-1991 ER - TY - JOUR AB - The choroid plexuses (ChPs) are the main regulators of cerebrospinal fluid (CSF) composition and thereby also control the composition of a principal source of signaling molecules that is in direct contact with neural stem cells in the developing brain. The regulators of ChP development mediating the acquisition of a fate that differs from the neighboring neuroepithelial cells are poorly understood. Here, we demonstrate in mice a crucial role for the transcription factor Otx2 in the development and maintenance of ChP cells. Deletion of Otx2 by the Otx2-CreERT2 driver line at E9 resulted in a lack of all ChPs, whereas deletion by the Gdf7-Cre driver line affected predominately the hindbrain ChP, which was reduced in size, primarily owing to an increase in apoptosis upon Otx2 deletion. Strikingly, Otx2 was still required for the maintenance of hindbrain ChP cells at later stages when Otx2 deletion was induced at E15, demonstrating a central role of Otx2 in ChP development and maintenance. Moreover, the predominant defects in the hindbrain ChP mediated by Gdf7-Cre deletion of Otx2 revealed its key role in regulating early CSF composition, which was altered in protein content, including the levels of Wnt4 and the Wnt modulator Tgm2. Accordingly, proliferation and Wnt signaling levels were increased in the distant cerebral cortex, suggesting a role of the hindbrain ChP in regulating CSF composition, including key signaling molecules. Thus, Otx2 acts as a master regulator of ChP development, thereby influencing one of the principal sources of signaling in the developing brain, the CSF. AU - Johansson, P.A. AU - Irmler, I. AU - Acampora, D.* AU - Beckers, J. AU - Simeone, A.* AU - Götz, M. C1 - 22524 C2 - 30901 SP - 1055-1066 TI - The transcription factor Otx2 regulates choroid plexus development and function. JO - Development VL - 140 IS - 5 PB - Company of Biologists Ltd. PY - 2013 SN - 0950-1991 ER - TY - JOUR AB - The discovery in the year 2000 that radial glial cells act as neural stem and progenitor cells in development has led to a change in the concept of neural stem cells in the adult brain. Not only are adult stem cells in the neurogenic niches glial in nature, but also glial cells outside these niches display greater potential when reacting to brain injury. Thus, a concept that emerged from developmental studies may hold the clue for neural repair. AU - Malatesta, P.* AU - Götz, M. C1 - 22514 C2 - 30904 SP - 483-486 TI - Radial glia - from boring cables to stem cell stars. JO - Development VL - 140 IS - 3 PB - Company of Biologists Ltd. PY - 2013 SN - 0950-1991 ER - TY - JOUR AB - To achieve adequate organ development and size, cell proliferation and differentiation have to be tightly regulated and coordinated. The transcription factor Pax6 regulates patterning, neurogenesis and proliferation in forebrain development. The molecular basis of this regulation is not well understood. As the bipartite DNA-binding paired domain of Pax6 regulates forebrain development, we examined mice with point mutations in its individual DNA-binding subdomains PAI (Pax6Leca4, N50K) and RED (Pax6Leca2, R128C). This revealed distinct roles in regulating proliferation in the developing cerebral cortex, with the PAI and RED subdomain mutations reducing and increasing, respectively, the number of mitoses. Conversely, neurogenesis was affected only by the PAI subdomain mutation, phenocopying the neurogenic defects observed in full Pax6 mutants. Genome-wide expression profiling identified molecularly discrete signatures of Pax6Leca4 and Pax6Leca2 mutations. Comparison to Pax6 targets identified by chromatin immunoprecipitation led to the identification and functional characterization of distinct DNA motifs in the promoters of target genes dysregulated in the Pax6Leca2 or Pax6Leca4 mutants, further supporting the distinct regulatory functions of the DNA-binding subdomains. Thus, Pax6 achieves its key roles in the developing forebrain by utilizing particular subdomains to coordinate patterning, neurogenesis and proliferation simultaneously. AU - Walcher, T. AU - Xie, Q.* AU - Sun, J.* AU - Irmler, M. AU - Beckers, J. AU - Öztürk, T. AU - Niessing, D. AU - Stoykova, A.* AU - Cvekl, A.* AU - Ninkovic, J. AU - Götz, M.-L. C1 - 22601 C2 - 30914 SP - 1123-1136 TI - Functional dissection of the paired domain of Pax6 reveals molecular mechanisms of coordinating neurogenesis and proliferation. JO - Development VL - 140 IS - 5 PB - Company of Biologists PY - 2013 SN - 0950-1991 ER - TY - JOUR AB - The Keystone Symposium entitled 'The Life of a Stem Cell: from Birth to Death' was held at Squaw Valley, CA, USA in March 2012. The meeting brought together researchers from across the world and showcased the most recent developments in stem cell research. Here, we review the proceedings at this meeting and discuss the major advances in fundamental and applied stem cell biology that emerged. AU - Chambers, I.* AU - Schroeder, T. C1 - 7751 C2 - 29882 SP - 2457-2461 TI - Stem cell powwow in Squaw Valley. JO - Development VL - 139 IS - 14 PB - Company of Biologists Ltd PY - 2012 SN - 0950-1991 ER - TY - JOUR AB - The thymus and parathyroid glands are derived from the third pharyngeal pouch endoderm. The mechanisms that establish distinct molecular domains in the third pouch and control the subsequent separation of these organ primordia from the pharynx are poorly understood. Here, we report that mouse embryos that lack two FGF feedback antagonists, Spry1 and Spry2, display parathyroid and thymus hypoplasia and a failure of these organ primordia to completely separate from the pharynx. We show that FGF ligands and downstream reporter genes are expressed in highly regionalised patterns in the third pouch and that sprouty gene deletion results in upregulated FGF signalling throughout the pouch endoderm. As a consequence, the initiation of markers of parathyroid and thymus fate is altered. In addition, a normal apoptotic programme that is associated with the separation of the primordia from the pharynx is disrupted, resulting in the maintenance of a thymus-pharynx attachment and a subsequent inability of the thymus to migrate to its appropriate position above the heart. We demonstrate that the sprouty genes function in the pharyngeal endoderm itself to control these processes and that the defects in sprouty-deficient mutants are, at least in part, due to hyper-responsiveness to Fgf8. Finally, we provide evidence to suggest that parathyroid hypoplasia in these mutants is due to early gene expression defects in the third pouch, whereas thymus hypoplasia is caused by reduced proliferation of thymic epithelial cells in the thymus primordium. AU - Gardiner, J.R.* AU - Jackson, A.L.* AU - Gordon, J.* AU - Lickert, H. AU - Manley, N.R.* AU - Basson, M.A.* C1 - 8619 C2 - 29594 SP - 3456-3466 TI - Localised inhibition of FGF signalling in the third pharyngeal pouch is required for normal thymus and parathyroid organogenesis. JO - Development VL - 139 IS - 18 PB - Company of Biologists Ltd. PY - 2012 SN - 0950-1991 ER - TY - JOUR AB - During development, spinal motoneurons (MNs) diversify into a variety of subtypes that are specifically dedicated to the motor control of particular sets of skeletal muscles or visceral organs. MN diversification depends on the coordinated action of several transcriptional regulators including the LIM-HD factor Isl1, which is crucial for MN survival and fate determination. However, how these regulators cooperate to establish each MN subtype remains poorly understood. Here, using phenotypic analyses of single or compound mutant mouse embryos combined with gain-of-function experiments in chick embryonic spinal cord, we demonstrate that the transcriptional activators of the Onecut family critically regulate MN subtype diversification during spinal cord development. We provide evidence that Onecut factors directly stimulate Isl1 expression in specific MN subtypes and are therefore required to maintain Isl1 production at the time of MN diversification. In the absence of Onecut factors, we observed major alterations in MN fate decision characterized by the conversion of somatic to visceral MNs at the thoracic levels of the spinal cord and of medial to lateral MNs in the motor columns that innervate the limbs. Furthermore, we identify Sip1 (Zeb2) as a novel developmental regulator of visceral MN differentiation. Taken together, these data elucidate a comprehensive model wherein Onecut factors control multiple aspects of MN subtype diversification. They also shed light on the late roles of Isl1 in MN fate decision. AU - Roy, A.* AU - Francius, C.* AU - Rousso, D.L.* AU - Seuntjens, E.* AU - Debruyn, J.* AU - Luxenhofer, G. AU - Huber, A.B. AU - Huylebroeck, D.* AU - Novitch, B.G.* AU - Clotman, F.* C1 - 8627 C2 - 30264 SP - 3109-3119 TI - Onecut transcription factors act upstream of Isl1 to regulate spinal motoneuron diversification. JO - Development VL - 139 IS - 17 PB - Company of Biologists Ltd. PY - 2012 SN - 0950-1991 ER - TY - JOUR AB - Successful brain development requires tight regulation of sequential symmetric and asymmetric cell division. Although Pax6 is known to exert multiple roles in the developing nervous system, its role in the regulation of cell division is unknown. Here, we demonstrate profound alterations in the orientation and mode of cell division in the cerebral cortex of mice deficient in Pax6 function (Pax6(Sey/Sey)) or after acute induced deletion of Pax6. Live imaging revealed an increase in non-vertical cellular cleavage planes, resulting in an increased number of progenitors with unequal inheritance of the apical membrane domain and adherens junctions in the absence of Pax6 function. This phenotype appears to be mediated by the direct Pax6 target Spag5, a microtubule-associated protein, reduced levels of which result in the replication of the Pax6 phenotype of altered cell division orientation. In addition, lack of Pax6 also results in premature delamination of progenitor cells from the apical surface due to an overall decrease in proteins mediating anchoring at the ventricular surface. Moreover, continuous long-term imaging in vitro revealed that Pax6-deficient progenitors generate daughter cells with asymmetric fates at higher frequencies. These data demonstrate a cell-autonomous role for Pax6 in regulating the mode of cell division independently of apicobasal polarity and cell-cell interactions. Taken together, our work reveals several direct effects that the transcription factor Pax6 has on the machinery that mediates the orientation and mode of cell division. AU - Asami, M. AU - Pilz, G.-A. AU - Ninkovic, J. AU - Godinho, L.* AU - Schroeder, T. AU - Huttner, W.B.* AU - Götz, M. C1 - 6693 C2 - 29130 SP - 5067-5078 TI - The role of Pax6 in regulating the orientation and mode of cell division of progenitors in the mouse cerebral cortex. JO - Development VL - 138 IS - 23 PB - Company of Biologists PY - 2011 SN - 0950-1991 ER - TY - JOUR AB - Little is known about the intrinsic specification of adult neural stem cells (NSCs) and to what extent they depend on their local niche. To observe adult NSC division and lineage progression independent of their niche, we isolated cells from the adult mouse subependymal zone (SEZ) and cultured them at low density without growth factors. We demonstrate here that SEZ cells in this culture system are primarily neurogenic and that adult NSCs progress through stereotypic lineage trees consisting of asymmetric stem cell divisions, symmetric transit-amplifying divisions and final symmetric neurogenic divisions. Stem cells, identified by their astro/radial glial identity and their slow-dividing nature, were observed to generate asymmetrically and fast-dividing cells that maintained an astro/radial glia identity. These, in turn, gave rise to symmetrically and fast-dividing cells that lost glial hallmarks, but had not yet acquired neuronal features. The number of amplifying divisions was limited to a maximum of five in this system. Moreover, we found that cell growth correlated with the number of subsequent divisions of SEZ cells, with slow-dividing astro/radial glia exhibiting the most substantial growth prior to division. The fact that in the absence both of exogenously supplied growth factors and of signals provided by the local niche neurogenic lineage progression takes place in such stereotypic fashion, suggests that lineage progression is, to a significant degree, cell intrinsic or pre-programmed at the beginning of the lineage. AU - Costa, M.R.* AU - Ortega, F.* AU - Brill, M.S.* AU - Beckervordersandforth, R. AU - Petrone, C. AU - Schroeder, T. AU - Götz, M. AU - Berninger, B. C1 - 6131 C2 - 28358 SP - 1057-1068 TI - Continuous live imaging of adult neural stem cell division and lineage progression in vitro. JO - Development VL - 138 IS - 6 PB - Company of Biologists Ltd PY - 2011 SN - 0950-1991 ER - TY - JOUR AB - The decision of a neural precursor to stop dividing and begin its terminal differentiation at the correct place, and at the right time, is a crucial step in the generation of cell diversity in the nervous system. Here, we show that the Down's syndrome candidate gene (Mnb/Dyrk1a) is transiently expressed in prospective neurons of vertebrate CNS neuroepithelia. The gain of function (GoF) of Mnb/Dyrk1a induced proliferation arrest. Conversely, its loss of function (LoF) caused over proliferation and cell death. We found that MNB/DYRK1A is both necessary and sufficient to upregulate, at transcriptional level, the expression of the cyclin-dependent kinase inhibitor p27(KIP1) in the embryonic chick spinal cord and mouse telencephalon, supporting a regulatory role for MNB/DYRK1A in cell cycle exit of vertebrate CNS neurons. All these actions required the kinase activity of MNB/DYRK1A. We also observed that MNB/DYRK1A is co-expressed with the NOTCH ligand Delta1 in single neuronal precursors. Furthermore, we found that MNB/DYRK1A suppressed NOTCH signaling, counteracted the pro-proliferative action of the NOTCH intracellular domain (NICD), stimulated Delta1 expression and was required for the neuronal differentiation induced by the decrease in NOTCH signaling. Nevertheless, although Mnb/Dyrk1a GoF led to extensive withdrawal of neuronal precursors from the cell cycle, it was insufficient to elicit their differentiation. Remarkably, a transient (ON/OFF) Mnb/Dyrk1a GoF efficiently induced neuronal differentiation. We propose that the transient expression of MNB/DYRK1A in neuronal precursors acts as a binary switch, coupling the end of proliferation and the initiation of neuronal differentiation by upregulating p27KIP1 expression and suppressing NOTCH signaling. AU - Hämmerle, B.* AU - Ulin, E.* AU - Guimera, J. AU - Becker, W.* AU - Guillemot, F.* AU - Tejedor, F.J.* C1 - 7174 C2 - 29519 SP - 2543-2554 TI - Transient expression of Mnb/Dyrk1a couples cell cycle exit and differentiation of neuronal precursors by inducing p27KIP1 expression and suppressing NOTCH signaling. JO - Development VL - 138 IS - 12 PB - Company of Biologists Ltd. PY - 2011 SN - 0950-1991 ER - TY - JOUR AB - The majority of the cortical cholinergic innervation implicated in attention and memory originates in the nucleus basalis of Meynert and in the horizontal limb of the diagonal band nucleus of the basal prosencephalon. Functional alterations in this system give rise to neuropsychiatric disorders as well as to the cognitive alterations described in Parkinson and Alzheimer's diseases. Despite the functional importance of these basal forebrain cholinergic neurons very little is known about their origin and development. Previous studies suggest that they originate in the medial ganglionic eminence of the telencephalic subpallium; however, our results identified Tbr1-expressing, reelin-positive neurons migrating from the ventral pallium to the subpallium that differentiate into cholinergic neurons in the basal forebrain nuclei projecting to the cortex. Experiments with Tbr1 knockout mice, which lack ventropallial structures, confirmed the pallial origin of cholinergic neurons in Meynert and horizontal diagonal band nuclei. Also, we demonstrate that Fgf8 signaling in the telencephalic midline attracts these neurons from the pallium to follow a tangential migratory route towards the basal forebrain. AU - Pombero, A.* AU - Bueno, C.* AU - Saglietti, L.* AU - Rodenas, M.* AU - Guimera, J. AU - Bulfone, A.* AU - Martinez, S.* C1 - 7175 C2 - 29520 SP - 4315-4326 TI - Pallial origin of basal forebrain cholinergic neurons in the nucleus basalis of Meynert and horizontal limb of the diagonal band nucleus. JO - Development VL - 138 IS - 19 PB - Company of Biologists Ltd. PY - 2011 SN - 0950-1991 ER - TY - JOUR AB - Neurogenesis is widespread in the zebrafish adult brain through the maintenance of active germinal niches. To characterize which progenitor properties correlate with this extensive neurogenic potential, we set up a method that allows progenitor cell transduction and tracing in the adult zebrafish brain using GFP-encoding retro- and lentiviruses. The telencephalic germinal zone of the zebrafish comprises quiescent radial glial progenitors and actively dividing neuroblasts. Making use of the power of clonal viral vector-based analysis, we demonstrate that these progenitors follow different division modes and fates: neuroblasts primarily undergo a limited amplification phase followed by symmetric neurogenic divisions; by contrast, radial glia are capable at the single cell level of both self-renewing and generating different cell types, and hence exhibit bona fide neural stem cell (NSC) properties in vivo. We also show that radial glial cells predominantly undergo symmetric gliogenic divisions, which amplify this NSC pool and may account for its long-lasting maintenance. We further demonstrate that blocking Notch signaling results in a significant increase in proliferating cells and in the numbers of clones, but does not affect clone composition, demonstrating that Notch primarily controls proliferation rather than cell fate. Finally, through long-term tracing, we illustrate the functional integration of newborn neurons in forebrain adult circuitries. These results characterize fundamental aspects of adult progenitor cells and neurogenesis, and open the way to using virus-based technologies for stable genetic manipulations and clonal analyses in the zebrafish adult brain. AU - Rothenaigner, I. AU - Krecsmarik, M.* AU - Hayes, J.A.* AU - Bahn, B. AU - Lepier, A.* AU - Fortin, G.* AU - Götz, M. AU - Jagasia, R.* AU - Bally-Cuif, L. C1 - 6297 C2 - 28328 SP - 1459-1469 TI - Clonal analysis by distinct viral vectors identifies bona fide neural stem cells in the adult zebrafish telencephalon and characterizes their division properties and fate. JO - Development VL - 138 IS - 8 PB - Company of Biologists Ltd PY - 2011 SN - 0950-1991 ER - TY - JOUR AB - The nucleosome remodelling complexes CHRAC and ACF of Drosophila are thought to play global roles in chromatin assembly and nucleosome dynamics. Disruption of the gene encoding the common ACF1 subunit compromises fly viability. Survivors show defects in chromatin assembly and chromatin-mediated gene repression at all developmental stages. We now show that ACF1 expression is under strict developmental control. The expression is strongly diminished during embryonic development and persists at high levels only in undifferentiated cells, including the germ cell precursors and larval neuroblasts. Constitutive expression of ACF1 is lethal. Cell-specific ectopic expression perturbs chromatin organisation and nuclear programmes. By monitoring heterochromatin formation during development, we have found that ACF1-containing factors are involved in the initial establishment of diversified chromatin structures, such as heterochromatin. Altering the levels of ACF1 leads to global and variegated deviations from normal chromatin organisation with pleiotropic defects. AU - Chioda, M.* AU - Vengadasalam, S.* AU - Kremmer, E. AU - Eberharter, A.* AU - Becker, P.B.* C1 - 4837 C2 - 27963 SP - 3513-3522 TI - Developmental role for ACF1-containing nucleosome remodellers in chromatin organisation. JO - Development VL - 137 IS - 20 PB - Company of Biologists Ltd. PY - 2010 SN - 0950-1991 ER - TY - JOUR AB - Homeodomain (HD) transcription factors and components of the Notch pathway [Delta1 (Dll1), Jagged1 (Jag1) and the Fringe (Fng) proteins] are expressed in distinct progenitor domains along the dorsoventral (DV) axis of the developing spinal cord. However, the internal relationship between these two regulatory pathways has not been established. In this report we show that HD proteins act upstream of Notch signalling. Thus, HD proteins control the spatial distribution of Notch ligands and Fng proteins, whereas perturbation of the Notch pathway does not affect the regional expression of HD proteins. Loss of Dll1 or Jag1 leads to a domain-specific increase of neuronal differentiation but does not affect the establishment of progenitor domain boundaries. Moreover, gain-of-function experiments indicate that the ability of Dll1 and Jag1 to activate Notch is limited to progenitors endogenously expressing the respective ligand. Fng proteins enhance Dll1-activated Notch signalling and block Notch activation mediated by Jag1. This finding, combined with the overlapping expression of Fng with Dll1 but not with Jag1, is likely to explain the domain-specific activity of the Notch ligands. This outcome is opposite to the local regulation of Notch activity in most other systems, including the Drosophila wing, where Fng co-localizes with Jagged/Serrate rather than Dll/Delta, which facilitates Notch signalling at regional boundaries instead of within domains. The regulation of Notch activation in the spinal cord therefore appears to endow specific progenitor populations with a domain-wide autonomy in the control of neurogenesis and prevents any inadequate activation of Notch across progenitor domain boundaries. AU - Marklund, U.* AU - Hansson, E.M.* AU - Sundström, E.* AU - Hrabě de Angelis, M. AU - Przemeck, G.K.H. AU - Lendahl, U.* AU - Muhr, J.* AU - Ericson, J.* C1 - 431 C2 - 27191 SP - 437-445 TI - Domain-specific control of neurogenesis achieved through patterned regulation of Notch ligand expression. JO - Development VL - 137 IS - 3 PB - Company of Biologists Ltd. PY - 2010 SN - 0950-1991 ER - TY - JOUR AB - In the mouse, one of the earliest events in the determination of cell fate is the segregation of cells into germ layers during gastrulation; however, the cellular and molecular details are not well defined due to intrauterine development. We were able to visualize a clear sequence of events occurring in the process of germ-layer formation, using immunohistochemistry and time-lapse confocal imaging. The T-box transcription factor brachyury (T) and the Forkhead transcription factor Foxa2 specify mesoderm and endoderm in the posterior epiblast. Fate-specified epiblast cells lose their polarity and undergo epithelial-mesenchymal transition to invade into the primitive streak region, where these cell populations quickly separate and differentiate into morphologically and molecularly distinct Foxa2-positive endoderm and T-positive mesoderm populations. The endoderm cells flatten and acquire apical-basal polarity during intercalation into the outside epithelium in order to establish proper intracellular junctions with pre-existing cells. By contrast, the mesodermal cells become spherical during migration and acquire a mesenchymal fate. Interestingly, axial mesodermal cells are descended from Foxa2-positive epiblast cells that upregulate T protein in the anterior primitive streak region. These cells, as well as Foxa2-positive endoderm cells, are highly polarized and epithelialized, suggesting that Foxa2 promotes an epithelial fate and suppresses a mesenchymal fate. This observation is supported by the fact that Foxa2 mutant endodermal cells fail to maintain polarity and do not establish proper cellular junctions, and are thus unable to functionally integrate into the endoderm epithelium. We propose that Foxa2 regulates a molecular program that induces an epithelial cellular phenotype. AU - Burtscher, I. AU - Lickert, H. C1 - 1085 C2 - 26642 SP - 1029-1038 TI - Foxa2 regulates polarity and epithelialization in the endoderm germ layer of the mouse embryo. JO - Development VL - 136 IS - 6 PB - Company Of Biologists PY - 2009 SN - 0950-1991 ER - TY - JOUR AB - Midbrain GABAergic neurons control several aspects of behavior, but regulation of their development and diversity is poorly understood. Here, we further refine the midbrain regions active in GABAergic neurogenesis and show their correlation with the expression of the transcription factor Gata2. Using tissue-specific inactivation and ectopic expression, we show that Gata2 regulates GABAergic neuron development in the mouse midbrain, but not in rhombomere 1, where it is needed in the serotonergic lineage. Without Gata2, all the precursors in the embryonic midbrain fail to activate GABAergic neuron-specific gene expression and instead switch to a glutamatergic phenotype. Surprisingly, this fate switch is also observed throughout the neonatal midbrain, except for the GABAergic neurons located in the ventral dopaminergic nuclei, suggesting a distinct developmental pathway for these neurons. These studies identify Gata2 as an essential post-mitotic selector gene of the GABAergic neurotransmitter identity and demonstrate developmental heterogeneity of GABAergic neurons in the midbrain. AU - Kala, K.* AU - Haugas, M.* AU - Lilleväli, K.* AU - Guimera, J. AU - Wurst, W. AU - Salminen, M.* AU - Partanen, J.* C1 - 776 C2 - 26080 SP - 253-262 TI - Gata2 is a tissue-specific post-mitotic selector gene for midbrain GABAergic neurons. JO - Development VL - 136 IS - 2 PB - Company Of Biologists PY - 2009 SN - 0950-1991 ER - TY - JOUR AB - Previous studies have identified roles of the modulation of Notch activation by Fringe homologues in boundary formation and in regulating the differentiation of vertebrate thymocytes and Drosophila glial cells. We have investigated the role of Lunatic fringe (Lfng) expression during neurogenesis in the vertebrate neural tube. We find that in the zebrafish hindbrain, Lfng is expressed by progenitors in neurogenic regions and downregulated in cells that have initiated neuronal differentiation. Lfng is required cell autonomously in neural epithelial cells to limit the amount of neurogenesis and to maintain progenitors. By contrast, Lfng is not required for the role of Notch in interneuronal fate choice, which we show is mediated by Notch1a. The expression of Lfng does not require Notch activity, but rather is regulated downstream of proneural genes that are widely expressed by neural progenitors. These findings suggest that Lfng acts in a feedback loop downstream of proneural genes, which, by promoting Notch activation, maintains the sensitivity of progenitors to lateral inhibition and thus limits further proneural upregulation. AU - Nikolaou, N.* AU - Watanabe-Asaka, T.* AU - Gerety, S.* AU - Distel, M. AU - Köster, R.W. AU - Wilkinson, D.G. C1 - 286 C2 - 26997 SP - 2523-2533 TI - Lunatic fringe promotes the lateral inhibition of neurogenesis. JO - Development VL - 136 IS - 15 PB - Company of Biologists PY - 2009 SN - 0950-1991 ER - TY - JOUR AB - Little is known about the cues controlling the generation of motoneuron populations in the mammalian ventral midbrain. We show that Otx2 provides the crucial anterior-posterior positional information for the generation of red nucleus neurons in the murine midbrain. Moreover, the homeodomain transcription factor Nkx6-1 controls the proper development of the red nucleus and of the oculomotor and trochlear nucleus neurons. Nkx6-1 is expressed in ventral midbrain progenitors and acts as a fate determinant of the Brn3a(+) (also known as Pou4f1) red nucleus neurons. These progenitors are partially dorsalized in the absence of Nkx6-1, and a fraction of their postmitotic offspring adopts an alternative cell fate, as revealed by the activation of Dbx1 and Otx2 in these cells. Nkx6-1 is also expressed in postmitotic Isl1(+) oculomotor and trochlear neurons. Similar to hindbrain visceral (branchio-) motoneurons, Nkx6-1 controls the proper migration and axon outgrowth of these neurons by regulating the expression of at least three axon guidance/neuronal migration molecules. Based on these findings, we provide additional evidence that the developmental mechanism of the oculomotor and trochlear neurons exhibits more similarity with that of special visceral motoneurons than with that controlling the generation of somatic motoneurons located in the murine caudal hindbrain and spinal cord. AU - Prakash, N. AU - Puelles, E.* AU - Freude, K.* AU - Trümbach, D. AU - Omodei, D.* AU - di Salvio, M.* AU - Sussel, L.* AU - Ericson, J.* AU - Sander, M.* AU - Simeone, A.* AU - Wurst, W. C1 - 555 C2 - 26291 SP - 2545-2555 TI - Nkx6-1 controls the identity and fate of red nucleus and oculomotor neurons in the mouse midbrain. JO - Development VL - 136 IS - 15 PB - Company Of Biologists Ltd PY - 2009 SN - 0950-1991 ER - TY - JOUR AB - The size of brain regions depends on the balance between proliferation and differentiation. During development of the mouse cerebral cortex, ventricular zone (VZ) progenitors, neuroepithelial and radial glial cells, enlarge the progenitor pool by proliferative divisions, while basal progenitors located in the subventricular zone (SVZ) mostly divide in a differentiative mode generating two neurons. These differences correlate to the existence of an apico-basal polarity in VZ, but not SVZ, progenitors. Only VZ progenitors possess an apical membrane domain at which proteins of the Par complex are strongly enriched. We describe a prominent decrease in the amount of Par-complex proteins at the apical surface during cortical development and examine the role of these proteins by gain- and loss-of-function experiments. Par3 (Pard3) loss-of-function led to premature cell cycle exit, reflected in reduced clone size in vitro and the restriction of the progeny to the lower cortical layers in vivo. By contrast, Par3 or Par6 (Pard6alpha) overexpression promoted the generation of Pax6+ self-renewing progenitors in vitro and in vivo and increased the clonal progeny of single progenitors in vitro. Time-lapse video microscopy revealed that a change in the mode of cell division, rather than an alteration of the cell cycle length, causes the Par-complex-mediated increase in progenitors. Taken together, our data demonstrate a key role for the apically located Par-complex proteins in promoting self-renewing progenitor cell divisions at the expense of neurogenic differentiation in the developing cerebral cortex. AU - Costa, M.R. AU - Wen, G. AU - Lepier, A.* AU - Schroeder, T. AU - Götz, M. C1 - 2389 C2 - 25243 SP - 11-28 TI - Par-complex proteins promote proliferative progenitor divisions in the developing mouse cerebral cortex. JO - Development VL - 135 IS - 1 PB - Company of Biologists PY - 2008 SN - 0950-1991 ER - TY - JOUR AB - Semaphorins and their receptors, plexins, carry out important functions during development and disease. In contrast to the well-characterized plexin A family, however, very little is known about the functional relevance of B-type plexins in organogenesis, particularly outside the nervous system. Here, we demonstrate that plexin B1 and its ligand Sema4d are selectively expressed in epithelial and mesenchymal compartments during key steps in the genesis of some organs. This selective expression suggests a role in epithelial-mesenchymal interactions. Importantly, using the developing metanephros as a model system, we have observed that endogenously expressed and exogenously supplemented Sema4d inhibits branching morphogenesis during early stages of development of the ureteric collecting duct system. Our results further suggest that the RhoA-ROCK pathway, which is activated downstream of plexin B1, mediates these inhibitory morphogenetic effects of Sema4d and suppresses branch-promoting signalling effectors of the plexin B1 signalling complex. Finally, mice that lack plexin B1 show early anomalies in kidney development in vivo. These results identify a novel function for plexin B1 as a negative regulator of branching morphogenesis during kidney development, and suggest that the Sema4d-plexin B1 ligand-receptor pair contributes to epithelial-mesenchymal interactions during organogenesis via modulation of RhoA signalling. AU - Korostylev, A.* AU - Worzfeld, T.* AU - Deng, S.* AU - Friedel, R.H. AU - Swiercz, J.M.* AU - Vodrazka, P.* AU - Maier, V. AU - Hirschberg, A.* AU - Ohoka, Y.* AU - Inagaki, S.* AU - Offermanns, S.* AU - Kuner, R.* C1 - 199 C2 - 27579 SP - 3333-3343 TI - A functional role for semaphorin 4D/plexin B1 interactions in epithelial branching morphogenesis during organogenesis. JO - Development VL - 135 IS - 20 PB - Company of Biologists Ltd. PY - 2008 SN - 0950-1991 ER - TY - JOUR AB - The role of the Notch signaling members Notch1, Notch2 and Rbpj in exocrine pancreatic development is not well defined. We therefore analyzed conditional pancreas-specific Rbpj and combined Notch1/Notch2 knockout mice using Ptf1a(+/Cre(ex1)) mice crossed with floxed Rbpj or Notch1/Notch2 mice. Mice were analyzed at different embryonic stages for pancreatic exocrine and endocrine development. The absence of Rbpj in pancreatic progenitor cells impaired exocrine pancreas development up to embryonic day 18.5 and led to premature differentiation of pancreatic progenitors into endocrine cells. In Rbpj-deficient pancreata, amylase-expressing acini and islets formed during late embryonic and postnatal development, suggesting an essential role of Rbpj in early but not late development. Contrary to this severe phenotype, the concomitant inactivation of Notch1 and Notch2 only moderately disturbed the proliferation of pancreatic epithelial cells during early embryonic development, and did not inhibit pancreatic development. Our results show that, in contrast to Rbpj, Notch1 and Notch2 are not essential for pancreatogenesis. These data favor a Notch-independent role of Rbpj in the development of the exocrine pancreas. Furthermore, our findings suggest that in late stages of pancreatic development exocrine cell differentiation and maintenance are independent of Rbpj. AU - Nakhai, H.* AU - Sievke, J. T.* AU - Klein, B.* AU - Mendoza-Torres, L* AU - Mazur, P. K.* AU - Algül, H.* AU - Radtke, F.* AU - Strobl, L.J. AU - Zimber-Strobl, U. AU - Schmid, R.M.* C1 - 4896 C2 - 25458 SP - 2757-2765 TI - Conditional ablation of Notch signaling in pancreatic development. JO - Development VL - 135 IS - 16 PB - Company of Biologists PY - 2008 SN - 0950-1991 ER - TY - JOUR AB - Neuronal production in the midbrain-hindbrain domain (MH) of the vertebrate embryonic neural tube depends on a progenitor pool called the 'intervening zone' (IZ), located at the midbrain-hindbrain boundary. The progressive recruitment of IZ progenitors along the mediolateral (future dorsoventral) axis prefigures the earlier maturation of the MH basal plate. It also correlates with a lower sensitivity of medial versus lateral IZ progenitors to the neurogenesis inhibition process that maintains the IZ pool. This role is performed in zebrafish by the E(Spl) factors Her5 and Her11, but the molecular cascades cooperating with Her5/11, and those accounting for their reduced effect in the medial IZ, remain unknown. We demonstrate here that the kinases Gsk3 beta and cAMP-dependent protein kinase A (PKA) are novel determinants of IZ formation and cooperate with E( Spl) activity in a dose-dependent manner. Similar to E(Spl), we show that the activity of Gsk3 beta/PKA is sensed differently by medial versus lateral IZ progenitors. Furthermore, we identify the transcription factor Gli1, expressed in medial IZ cells, as an antagonist of E(Spl) and Gsk3 beta/ PKA, and demonstrate that the neurogenesis-promoting activity of Gli1 accounts for the reduced sensitivity of medial IZ progenitors to neurogenesis inhibitors and their increased propensity to differentiate. We also show that the expression and activity of Gli1 in this process are, surprisingly, independent of Hedgehog signaling. Together, our results suggest a model in which the modulation of E(Spl) and Gsk3 beta/PKA activities by Gli1 underlies the dynamic properties of IZ maintenance and recruitment. AU - Ninkovic, J. AU - Stigloher, C. AU - Lillesaar, C. AU - Bally-Cuif, L. C1 - 2982 C2 - 25856 SP - 3137-3148 TI - Gsk3 beta/PKA and Gli1 regulate the maintenance of neural progenitors at the midbrain-hindbrain boundary in concert with E(Spl) factor activity. JO - Development VL - 135 IS - 18 PB - Company of Biologists PY - 2008 SN - 0950-1991 ER - TY - JOUR AB - Meso-diencephalic dopaminergic (mdDA) neurons control voluntary movement, cognition and the reward response, and their degeneration is associated with Parkinson's disease (PD). Prospective cell transplantation therapies for PD require full knowledge of the developmental pathways that control mdDA neurogenesis. We have previously shown that Otx2 is required for the establishment of the mesencephalic field and molecular code of the entire ventral mesencephalon (VM). Here, we investigate whether Otx2 is a specific determinant of mesencephalic dopaminergic (mesDA) neurogenesis by studying mouse mutants that conditionally overexpress or lack Otx2. Our data show that Otx2 overexpression in the VM causes a dose-dependent and selective increase in both mesDA progenitors and neurons, which correlates with a remarkable and specific enhancement in the proliferating activity of mesDA progenitors. Consistently, lack of Otx2 in the VM specifically affects the proliferation of Sox2(+) mesDA progenitors and causes their premature post-mitotic transition. Analysis of the developmental pathway that controls the differentiation of mesDA neurons shows that, in the absence of Otx2, the expression of Lmx1a and Msx1, and the proneural genes Ngn2 and Mash1 is not activated in Sox2+ mesDA progenitors, which largely fail to differentiate into Nurr1(+) mesDA precursors. Furthermore, proliferation and differentiation abnormalities exhibit increasing severity along the anterior-posterior (AP) axis of the VM. These findings demonstrate that Otx2, through an AP graded effect, is intrinsically required to control proliferation and differentiation of mesDA progenitors. Thus, our data provide new insights into the mechanism of mesDA neuron specification and suggest Otx2 as a potential target for cell replacement-based therapeutic approaches in PD. AU - Omodei, D.* AU - Acampora, D.* AU - Mancuso, P.* AU - Prakash, N. AU - di Giovannantonio, L.G.* AU - Wurst, W. AU - Simeone, A.* C1 - 2309 C2 - 25894 SP - 3459-3470 TI - Anterior-posterior graded response to Otx2 controls proliferation and differentiation of dopaminergic progenitors in the ventral mesencephalon. JO - Development VL - 135 IS - 20 PB - Company of Biologists Ltd. PY - 2008 SN - 0950-1991 ER - TY - JOUR AB - Basic helix-loop-helix (bHLH) transcription factors are important regulators of retinal neurogenesis. In the developing retina, proneural bHLH genes have highly defined expressions, which are influenced by pattern formation and cell-specification pathways. We report here that the tissue-specific bHLH transcription factor Ptf1a (also known as PTF1-p48) is expressed from embryonic day 12.5 of gestation (E12.5) to postnatal day 3 (P3) during retinogenesis in the mouse. Using recombination-based lineage tracing, we provide evidence that Ptf1a is expressed in precursors of amacrine and horizontal cells. Inactivation of Ptf1a in the developing retina led to differentiation arrest of amacrine and horizontal precursor cells in addition to partial transdifferentiation of Ptf1a-expressing precursor cells to ganglion cells. Analysis of late cell-type-specific markers revealed the presence of a small population of differentiated amacrine cells, whereas GABAergic and glycinergic amacrine cells, as well as horizontal cells, were completely missing in Ptf1a-knockout retinal explants. We conclude that Ptf1a contributes to the differentiation of horizontal cells and types of amacrine cells during mouse retinogenesis. AU - Nakhai, H.* AU - Sel, S.* AU - Favor, J. AU - Mendoza-Torres, L.* AU - Paulsen, F.* AU - Duncker, G.I.* AU - Schmid, R.M.* C1 - 3766 C2 - 24784 SP - 1151-1160 TI - Ptf1a is essential for the differentiation of GABAergic and glycinergic amacrine cells and horizontal cells in the mouse retina. JO - Development VL - 134 IS - 6 PB - Company of Biologists PY - 2007 SN - 0950-1991 ER - TY - JOUR AB - Although the local environment is known to regulate neural stem cell (NSC) maintenance in the central nervous system, little is known about the molecular identity of the signals involved. Chondroitin sulfate proteoglycans (CSPGs) are enriched in the growth environment of NSCs both during development and in the adult NSC niche. In order to gather insight into potential biological roles of CSPGs for NSCs, the enzyme chondroitinase ABC (ChABC) was used to selectively degrade the CSPG glycosaminoglycans. When NSCs from mouse E13 telencephalon were cultivated as neurospheres, treatment with ChABC resulted in diminished cell proliferation and impaired neuronal differentiation, with a converse increase in astrocytes. The intrauterine injection of ChABC into the telencephalic ventricle at midneurogenesis caused a reduction in cell proliferation in the ventricular zone and a diminution of self-renewing radial glia, as revealed by the neurosphere-formation assay, and a reduction in neurogenesis. These observations suggest that CSPGs regulate neural stem/progenitor cell proliferation and intervene in fate decisions between the neuronal and glial lineage. AU - Sirko, S.* AU - von Holst, A.* AU - Wizenmann, A. AU - Götz, M. AU - Faissner, A.* C1 - 2774 C2 - 24680 SP - 2727-2738 TI - Chondroitin sulfate glycosaminoglycans control proliferation, radial glia cell differentiation and neurogenesis in neural stem/progenitor cells. JO - Development VL - 134 IS - 15 PB - Company of Biologists PY - 2007 SN - 0950-1991 ER - TY - JOUR AU - Chapouton, P. AU - Adolf, B. AU - Leucht, C. AU - Ryu, S.* AU - Driever, W.* AU - Bally-Cuif, L. C1 - 2434 C2 - 23870 TI - Her5 expression reveals a pool of neural stem cells in the adult zebrafish midbrain. JO - Development VL - 133 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AU - Foucher, I.* AU - Mione, M.* AU - Simeone, A.* AU - Acampora, D.* AU - Bally-Cuif, L. AU - Houart, C.* C1 - 2547 C2 - 23868 SP - 1891-1900 TI - Differentiation of cerebellar cell identities in absence of Fgf signalling in zebrafish Otx morphants. JO - Development VL - 133 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AU - Guimera, J. AU - Vogt Weisenhorn, D.M. AU - Wurst, W. C1 - 3263 C2 - 23954 SP - 3847-3857 TI - Megane/Heslike is required for normal GABAergic differentiation in the mouse superior colliculus. JO - Development VL - 133 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AU - Haubst, N. AU - Georges-Labouesse, E.* AU - de Arcangelis, A.* AU - Mayer, U.* AU - Götz, M. C1 - 3505 C2 - 24130 SP - 3245-3254 TI - Basement membrane attachment is dispensable for radial glial cell fate and for proliferation, but affects positioning of neuronal subtypes. JO - Development VL - 133 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AU - Prakash, N. AU - Brodski, C.* AU - Naserke, T. AU - Puelles, E.* AU - Gogoi, R.* AU - Hall, A.* AU - Panhuysen, M. AU - Echevarria, D.* AU - Sussel, L.* AU - Vogt Weisenhorn, D.M. AU - Martinez, S.* AU - Arenas, E* AU - Simeone, A* AU - Wurst, W. C1 - 4961 C2 - 23318 SP - 89-98 TI - A Wnt1-regulated genetic network controls the identity and fate of midbrain-dopaminergic progenitors in vivo. JO - Development VL - 133 IS - 1 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AB - Anteroposterior patterning of the vertebrate forebrain during gastrulation involves graded Wnt signaling, which segregates anterior fields (telencephalon and eye) from the diencephalon. How the telencephalic and retinal primordia are subsequently subdivided remains largely unknown. We demonstrate that at late gastrulation the Paired-like homeodomain transcription factor Rx3 biases cell specification choices towards the retinal fate within a population of bipotential precursors of the anterior forebrain: direct cell tracing demonstrates that retinal precursors acquire a telencephalic fate in embryos homozygous for the rx3-null allele ckh(ne2611), characterized by an enlarged telencephalon and a lack of eyes. Chimera analyses further indicate that this function of Rx3 is cell autonomous. Transfating of the eye field in the absence of Rx3 function correlates with a substantial posterior expansion of expression of the Wnt antagonist Tlc and the winged-helix transcription factor Foxg1. These results suggest that the process segregating the telencephalic and eye fields is isolated from diencephalic patterning, and is mediated by Rx3. AU - Stigloher, C. AU - Ninkovic, J. AU - Laplante, M.* AU - Geling, A. AU - Tannhäuser, B. AU - Topp, S. AU - Kikuta, H.* AU - Becker, T.S.* AU - Houart, C. AU - Bally-Cuif, L. C1 - 2548 C2 - 23869 SP - 2925-2935 TI - Segregation of telencephalic and eye-field identities inside the zebrafish forebrain territory is controlled by Rx3. JO - Development VL - 133 IS - 15 PB - Company of Biologists PY - 2006 SN - 0950-1991 ER - TY - JOUR AB - Defects in cardiac valve morphogenesis and septation of the heart chambers constitute some of the most common human congenital abnormalities. Some of these defects originate from errors in atrioventricular (AV) endocardial cushion development. Although this process is being extensively studied in mouse and chick, the zebrafish system presents several advantages over these models, including the ability to carry out forward genetic screens and study vertebrate gene function at the single cell level. In this paper, we analyze the cellular and subcellular architecture of the zebrafish heart during stages of AV cushion and valve development and gain an unprecedented level of resolution into this process. We find that endocardial cells in the AV canal differentiate morphologically before the onset of epithelial to mesenchymal transformation, thereby defining a previously unappreciated step during AV valve formation. We use a combination of novel transgenic lines and fluorescent immunohistochemistry to analyze further the role of various genetic (Notch and Calcineurin signaling) and epigenetic (heart function) pathways in this process. In addition, from a large-scale forward genetic screen we identified 55 mutants, defining 48 different genes, that exhibit defects in discrete stages of AV cushion development. This collection of mutants provides a unique set of tools to further our understanding of the genetic basis of cell behavior and differentiation during AV valve development. AU - Beis, D.* AU - Tallafuß, A. AU - Bally-Cuif, L. C1 - 3520 C2 - 23151 SP - 4193-4204 TI - Genetic and cellular analyses of zebrafish atrioventricular cushion and valued development. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - The fascinating question of how the enormous diversity of neuronal and glial cells in the cerebral cortex is generated during development was recently discussed at a meeting on cortical development and stem cells in Greece. What emerged from this meeting is an equally fascinating answer, namely that precursor diversity at rather early stages of development anticipates later cell type diversity. AU - Götz, M. AU - Sommer, L.* C1 - 3029 C2 - 23400 SP - 3327-3332 TI - Cortical Development: The art of generating cell diversity. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - Cranial sensory neurons largely derive from neurogenic placodes (epibranchial and dorsolateral), which are ectodermal thickenings that form the sensory ganglia associated with cranial nerves, but the molecular mechanisms of placodal development are unclear. Here, we show that the pharyngeal endoderm induces epibranchial neurogenesis in zebrafish, and that BMP signaling plays a crucial role in this process. Using a her5:egfp transgenic line to follow endodermal movements in living embryos, we show that contact between pharyngeal pouches and the surface ectoderm coincides with the onset of neurogenesis in epibranchial placodes. By genetic ablation and reintroduction of endoderm by cell transplantation, we show that these contacts promote neurogenesis. Using a genetic interference approach we further identify bmp2b and bmp5 as crucial components of the endodermal signals that induce epibranchial neurogenesis. Dorsolateral placodes (trigeminal, auditory, vestibular, lateral line) develop independently of the endoderm and BMP signaling, suggesting that these two sets of placodes are under separate genetic control. Our results show that the endoderm regulates the differentiation of cranial sensory ganglia, which coordinates the cranial nerves with the segments that they innervate. AU - Holzschuh, J.* AU - Wada, N.* AU - Wada, C.* AU - Schaffer, A.* AU - Javidan, Y.* AU - Tallafuß, A. AU - Bally-Cuif, L. AU - Schilling, T.F.* C1 - 604 C2 - 23150 SP - 3731-3742 TI - Requirements for endoderm and BMP signaling in sensory neurogenesis in zebrafish. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - Differential gene regulation integrated in time and space drives developmental programs during embryogenesis. To understand how the program of gastrulation is regulated by Wnt/β-catenin signaling, we have used genome-wide expression profiling of conditional β-catenin mutant embryos. Known Wnt/β-catenin target genes, known components of other signaling pathways, as well as a number of uncharacterized genes were downregulated in these mutants. To further narrow down the set of differentially expressed genes, we used whole-mount in situ screening to associate gene expression with putative domains of Wnt activity. Several potential novel target genes were identified by this means and two, Grsf1 and Fragilis2, were functionally analyzed by RNA interference (RNAi) in completely embryonic stem (ES) cell-derived embryos. We show that the gene encoding the RNA-binding factor Grsf1 is important for axial elongation, mid/hindbrain development and axial mesoderm specification, and that Fragilis2, encoding a transmembrane protein, regulates epithelialization of the somites and paraxial mesoderm formation. Intriguingly, the knock-down phenotypes recapitulate several aspects of Wnt pathway mutants, suggesting that these genes are components of the downstream Wnt response. This functional genomic approach allows the rapid identification of functionally important components of embryonic development from large datasets of putative targets. AU - Lickert, H. AU - Cox, B.* AU - Wehrle, C.* AU - Taketo, M.M.* AU - Kemler, R.* AU - Rossant, J.* C1 - 3636 C2 - 23057 SP - 2599-2609 TI - Dissecting Wnt/ß-catenin signaling during gastrulation using RNA interference in mouse embryos. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - The intervening zone (IZ) is a pool of progenitor cells located at the midbrain-hindbrain boundary (MHB) and important for MHB maintenance, midbrain-hindbrain growth and the generation of midbrain-hindbrain neurons. Recently, we implicated the Hairy/E(spl) transcription factor Her5 in the formation of the medial (most basal) part of the IZ (MIZ) in zebrafish; the molecular bases for lateral IZ (LIZ) formation, however, remain unknown. We now demonstrate that her5 is physically linked to a new family member, him, displaying an identical MHB expression pattern. Using single and double knockdowns of him and her5, as well as a him+her5 deletion mutant background (b404), we demonstrate that Him and Her5 are equally necessary for MIZ formation, and that they act redundantly in LIZ formation in vivo. We show that these processes do not involve cross-regulation between Him and Her5 expression or activities, although Him and Her5 can heterodimerize with high affinity. Increasing the function of one factor when the other is depleted further shows that Him and Her5 are functionally interchangeable. Together, our results demonstrate that patterning and neurogenesis are integrated by the her5-him gene pair to maintain a progenitor pool at the embryonic MHB. We propose a molecular mechanism for this process where the global `Him+Her5' activity inhibits ngn1 expression in a dose-dependent manner and through different sensitivity thresholds along the medio-lateral axis of the neural plate. AU - Ninkovic, J.* AU - Tallafuss, A.* AU - Leucht, C.* AU - Topczewski, J.* AU - Tannhäuser, B.* AU - Solnica-Krezel, L.* AU - Bally-Cuif, L. C1 - 967 C2 - 23148 SP - 75-88 TI - Inhibition of neurogenesis at the zebrafish midbrain-hindbrain boundary by the combined and dose-dependent activity of a new hairylE(spl) gene pair. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - During Arabidopsis embryo development, cotyledon primordia are generated at transition stage from precursor cells that are not derived from the embryonic shoot apical meristem (SAM). To date, it is not known which genes specifically instruct these precursor cells to elaborate cotyledons, nor is the role of auxin in cotyledon development clear. In laterne mutants, the cotyledons are precisely deleted, yet the hypocotyl and root are unaffected. The laterne phenotype is caused by a combination of two mutations: one in the PINOID (PID) gene and another mutation in a novel locus designated ENHANCER OF PINOID (ENP). The expression domains of shoot apex organising genes such as SHOOT MERISTEMLESS (STM) extend along the entire apical region of laterne embryos. However, analysis of pid enp stm triple mutants shows that ectopic activity of STM does not appear to cause cotyledon obliteration. This is exclusively caused by enp in concert with pid. In pinoid embryos, reversal of polarity of the PIN1 auxin transport facilitator in the apex is only occasional, explaining irregular auxin maxima in the cotyledon tips. By contrast, polarity of PIN1:GFP is completely reversed to basal position in the epidermal layer of the laterne embryo. Consequently auxin, which is believed to be essential for organ formation, fails to accumulate in the apex. This strongly suggests that ENP specifically regulates cotyledon development through control of PIN1 polarity in concert with PID. AU - Treml, B.S.* AU - Winderl, S.* AU - Radykewicz, R.* AU - Herz, M.* AU - Schweizer, G.* AU - Hutzler, P. AU - Glawischnig, E.* AU - Ruiz, R.A.T.* C1 - 769 C2 - 22859 SP - 4063-4074 TI - The gene ENHANCER OF PINOID controls cotyledon development in the Arabidopsis embryo. JO - Development VL - 132 PB - Company of Biologists PY - 2005 SN - 0950-1991 ER - TY - JOUR AB - Neurogenesis in both vertebrates and invertebrates is tightly controlled in time and space involving both positive and negative regulators. We report here that the bHLH factor Her5 acts as a prepattern gene to prevent neurogenesis in the anlage of the midbrain/hindbrain boundary in the zebrafish neural plate. This involves selective suppression of both neurogenin1 (ngn1) and coe2 mRNA expression in a process that is independent of Notch signalling, and where inhibition of either ngn1 or coe2 expression is sufficient to prevent neuronal differentiation across the midbrain-hindbrain boundary. A ngn1 transgene faithfully responds to Her5 and deletion analysis of the transgene identifies an E-box in a ngn1 upstream enhancer to be required for repression by Her5. Together our data demonstrate a role of Her5 as a prepattern factor in the spatial definition of proneural domains in the zebrafish neural plate, in a manner similar to its Drosophila homologue Hairy. AU - Geling, A.* AU - Plessy, C.* AU - Rastegar, S.* AU - Strähle, U.* AU - Bally-Cuif, L. C1 - 4948 C2 - 22309 SP - 1993-2006 TI - Her5 acts as a prepattern factor that blocks neurogenin1 and coe2 expression upstream of notch to inhibit neurogenesis at the midbrain-hindbrain boundary. JO - Development VL - 131 IS - 9 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - The transcription factor Pax6 plays a key role during development of various organs, including the brain where it affects cell fate, cell proliferation and patterning. To understand how Pax6 coordinates these diverse effects at the molecular level, we examined the role of distinct DNA-binding domains of Pax6, the homeodomain (HD), the paired domain (PD) and its splice variant (5a), using loss- and gain-of-function approaches. Here we show that the PD is necessary for the regulation of neurogenesis, cell proliferation and patterning effects of Pax6, since these aspects are severely affected in the developing forebrain of the Pax6Aey18 mice with a deletion in the PD but intact homeo- and transactivation domains. In contrast, a mutation of the HD lacking DNA-binding (Pax64Neu) resulted in only subtle defects of forebrain development. We further demonstrate distinct roles of the two splice variants of the PD. Retrovirally mediated overexpression of Pax6 containing exon 5a inhibited cell proliferation without affecting cell fate, while Pax6 containing the canonical form of the PD lacking exon 5a affected simultaneously cell fate and proliferation. These results therefore demonstrate a key role of the PD in brain development and implicate splicing as a pivotal factor regulating the potent neurogenic role of Pax6. AU - Haubst, N. AU - Berger, J.* AU - Radjendirane, V.* AU - Graw, J. AU - Favor, J. AU - Saunders, G.F.* AU - Stoykova, A.* AU - Götz, M. C1 - 2910 C2 - 22170 SP - 6131-6140 TI - Molecular dissection of Pax6 function: The specific roles of the paired domain and homeodomain in brain development. JO - Development VL - 131 IS - 24 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - Here, we present evidence that Lrp6, a coreceptor for Wnt ligands, is required for the normal formation of somites and bones. By positional cloning, we demonstrate that a novel spontaneous mutation ringelschwanz (rs) in the mouse is caused by a point mutation in Lrp6, leading to an amino acid substitution of tryptophan for the evolutionarily conserved residue arginine at codon 886 (R886W). We show that rs is a hypomorphic Lrp6 allele by a genetic complementation test with Lrp6-null mice, and that the mutated protein cannot efficiently transduce signals through the Wnt/β-catenin pathway. Homozygous rs mice, many of which are remarkably viable, exhibit a combination of multiple Wnt-deficient phenotypes, including dysmorphologies of the axial skeleton, digits and the neural tube. The establishment of the anteroposterior somite compartments, the epithelialization of nascent somites, and the formation of segment borders are disturbed in rs mutants, leading to a characteristic form of vertebral malformations, similar to dysmorphologies in individuals suffering from spondylocostal dysostosis. Marker expression study suggests that Lrp6 is required for the crosstalk between the Wnt and notch-delta signaling pathways during somitogenesis. Furthermore, the Lrp6 dysfunction in rs leads to delayed ossification at birth and to a low bone mass phenotype in adults. Together, we propose that Lrp6 is one of the key genetic components for the pathogenesis of vertebral segmentation defects and of osteoporosis in humans. AU - Kokubu, C. AU - Heinzmann, U. AU - Kokubu, T. AU - Sakai, N.* AU - Kubota, T.* AU - Kawai, M.* AU - Wahl, M.B. AU - Galceran, J.* AU - Grosschedl, R.* AU - Ozono, K.* AU - Imai, K. C1 - 2354 C2 - 22171 SP - 5469-5480 TI - Skeletal defects in ringelschwanz mutant mice reveal that Lrp6 is required for proper somitogenesis and osteogenesis. JO - Development VL - 131 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - Methyl-DNA binding proteins play an important role in epigenetic gene regulation. The Drosophila genome encodes a single protein (MBD2/3) with extended homologies to the vertebrate methyl-DNA binding proteins MBD2 and MBD3. However, very little is known about its functional properties. We have now characterized an MBD2/3 null mutant allele that is viable and fertile. This mutation caused a strong dominant suppression of position-effect variegation and also resulted in a high rate of chromosome segregation defects during early embryogenesis. Confocal analysis of mutant embryos showed local displacement of MI-2 from DNA and indicated that MBD2/3 is associated with only a subset of MI-2 complexes. In addition, band shift experiments demonstrated a specific binding of MBD2/3 to CpT/A-methylated DNA, which reflects the endogenous DNA methylation pattern of Drosophila. Consistently, the localization of MBD2/3 was disrupted in embryos with reduced levels of DNA methylation. Our data provide novel insights into the function of MBD2/3 proteins and strongly suggest the existence of methylation-dependent chromatin structures in Drosophila. AU - Marhold, J.* AU - Kramer, K.* AU - Kremmer, E. AU - Lyko, F.* C1 - 1797 C2 - 22328 SP - 6033-6039 TI - The Drosophila MBD2/3 protein mediates interactions between the MI-2 chromatin complex and CpT/A-methylated DNA. JO - Development VL - 131 IS - 24 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - The specification of distinct neuronal cell-types is controlled by inducing signals whose interpretation in distinct areas along the central nervous system provides neuronal progenitors with a precise and typical expression code of transcription factors. To gain insights into this process, we investigated the role of Otx2 in the specification of identity and fate of neuronal progenitors in the ventral midbrain. To achieve this, Otx2 was inactivated by Cre recombinase under the transcriptional control of En1. Lack of Otx2 in the ventrolateral and posterior midbrain results in a dorsal expansion of Shh expression and in a dorsal and anterior rotation of the midbrain-hindbrain boundary and Fgf8 expression. Indeed, in this mutant correct positioning of the ventral site of midbrain-hindbrain boundary and Fgf8 expression are efficiently controlled by Otx1 function, thus allowing the study of the identity and fate of neuronal progenitors of the ventral midbrain in the absence of Otx2. Our results suggest that Otx2 acts in two ways: by repressing Nkx2.2 in the ventral midbrain and maintaining the Nkx6.1-expressing domain through dorsal antagonism on Shh. Failure of this control affects the identity code and fate of midbrain progenitors, which exhibit features in common with neuronal precursors of the rostral hindbrain even though the midbrain retains its regional identity and these neuronal precursors are rostral to Fgf8 expression. Dopaminergic neurons are greatly reduced in number, red nucleus precursors disappear from the ventral midbrain where a relevant number of serotonergic neurons are generated. These results indicate that Otx2 is an essential regulator of the identity, extent and fate of neuronal progenitor domains in the ventral midbrain and provide novel insights into the mechanisms by which neuronal diversity is generated in the central nervous system. AU - Puelles, E.* AU - Annino, A.* AU - Tuorto, F.* AU - Usiello, A.* AU - Acampora, D.* AU - Czerny, T.* AU - Brodski, C. AU - Ang, S.-L.* AU - Wurst, W. AU - Simeone, A.* C1 - 2355 C2 - 22418 SP - 2037-2048 TI - Otx2 regulates the extent, identity and fate of neuronal progenitor domains in the ventral midbrain. JO - Development VL - 131 IS - 9 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - The mesencephalic dopamine (mesDA) system is involved in the control of movement and behavior. The expression of Pitx3 in the brain is restricted to the mesDA system and the gene is induced relatively late, at E11.5, a time when tyrosine hydroxylase (Th) gene expression is initiated. We show here that, in the Pitx3-deficient aphakia (ak) mouse mutant, the mesDA system is malformed. Owing to the developmental failure of mesDA neurons in the lateral field of the midbrain, mesDA neurons are not found in the SNc and the projections to the caudate putamen are selectively lost. However, Pitx3 is expressed in all mesDA neurons in control animals. Therefore, mesDA neurons react specifically to the loss of Pitx3. Defects of motor control where not seen in the ak mice, suggesting that other neuronal systems compensate for the absence of the nigrostriatal pathway. However, an overall lower activity was observed. The results suggest that Pitx3 is specifically required for the formation of the SNc subfield at the onset of dopaminergic neuron differentiation. AU - Smidt, M.P.* AU - Smits, S.M.* AU - Bouwmeester, H.* AU - Hamers, F.P.T.* AU - van der Linden, A.J.A.* AU - Hellemons, A.J.C.G.M.* AU - Graw, J. AU - Burbach, J.P.H.* C1 - 2103 C2 - 22082 SP - 1145-1155 TI - Early developmental failure of substantia nigra dopamine neurons in mice lacking the homeodomain gene Pitx3. JO - Development VL - 131 IS - 5 PB - Company of Biologists PY - 2004 SN - 0950-1991 ER - TY - JOUR AB - Numerous studies have demonstrated that the midbrain and cerebellum develop from a region of the early neural tube comprising two distinct territories known as the mesencephalon (mes) and rostral metencephalon (met; rhombomere 1), respectively. Development of the mes and met is thought to be regulated by molecules produced by a signaling center, termed the isthmic organizer (IsO), which is localized at the boundary between them. FGF8 and WNT1 have been implicated as key components of IsO signaling activity, and previous studies have shown that in Wnt1-/- embryos, the mes/met is deleted by the 30 somite stage (∼E10) (McMahon, A. P. and Bradley, A. (1990) Cell 62, 1073-1085). We have studied the function of FGF8 in mouse mes/met development using a conditional gene inactivation approach. In our mutant embryos, Fgf8 expression was transiently detected, but then was eliminated in the mes/met by the 10 somite stage (∼E8.75). This resulted in a failure to maintain expression of Wnt1 as well as Fgf17, Fgf18, and Gbx2 in the mes/met at early somite stages, and in the absence of the midbrain and cerebellum at E17.5. We show that a major cause of the deletion of these structures is ectopic cell death in the mes/met between the 7 and 30 somite stages. Interestingly, we found that the prospective midbrain was deleted at an earlier stage than the prospective cerebellum. We observed a remarkably similar pattern of cell death in Wnt1 null homozygotes, and also detected ectopic mes/met cell death in En1 null homozygotes. Our data show that Fgf8 is part of a complex gene regulatory network that is essential for cell survival in the mes/met. AU - Chi, C.L.* AU - Martinez, S.* AU - Wurst, W. AU - Martin, G.R.* C1 - 3585 C2 - 22453 SP - 2633-2644 TI - The isthmic organizer signal FGF8 is required for cell survival in the prospective midbrain and cerebellum. JO - Development VL - 130 IS - 12 PB - Company of Biologists PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - Olf/Ebf transcription factors have been implicated in numerous developmental processes, ranging from B-cell development to neuronal differentiation. We describe mice that carry a targeted deletion within the EbJ2 (O/E3) gene. In Ebf2-null mutants, because of defective migration of gonadotropin releasing hormone-synthesizing neurons, formation of the neuroendocrine axis (which is essential for pubertal development) is impaired, leading to secondary hypogonadism. In addition, Ebf2(-/-) peripheral nerves feature defective axon sorting, hypomyelination, segmental dysmyelination and axonal damage, accompanied by a sharp decrease in motor nerve conduction velocity. Ebf2-null mice reveal a novel genetic cause of hypogonadotropic hypogonadism and peripheral neuropathy in the mouse, disclosing an important role for Ebf2 in neuronal migration and nerve development. AU - Corradi, A.* AU - Croci, L.* AU - Broccoli, V.* AU - Zecchini, S.* AU - Previtali, S.* AU - Wurst, W. AU - Amadio, S.* AU - Maggi, R.* AU - Quattrini, A.* AU - Consalez, G.G.* C1 - 2321 C2 - 21732 SP - 401-410 TI - Hypogonadotropic hypogonadism and peripheral neuropathy in Ebf2-null mice. JO - Development VL - 130 IS - 2 PB - Company of Biologists PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - The midbrain-hindbrain (MH) domain of the vertebrate embryonic neural plate displays a stereotypical profile of neuronal differentiation, organized around a neuron-free zone ('intervening zone', IZ) at the midbrain-hindbrain boundary (MHB). The mechanisms establishing this early pattern of neurogenesis are unknown. We demonstrate that the MHB is globally refractory to neurogenesis, and that forced neurogenesis in this area interferes with the continued expression of genes defining MHB identity. We further show that expression of the zebrafish bHLH Hairy/E(spl)-related factor Her5 prefigures and then precisely delineates the IZ throughout embryonic development. Using morpholino knock-down and conditional gain-of-function assays, we demonstrate that Her5 is essential to prevent neuronal differentiation and promote cell proliferation in a medial compartment of the IZ. We identify one probable target of this activity, the zebrafish Cdk inhibitor p27Xic1. Finally, although the her5 expression domain is determined by anteroposterior patterning cues, we show Her5 does not retroactively influence MH patterning. Together, our results highlight the existence of a mechanism that actively inhibits neurogenesis at the MHB, a process that shapes MH neurogenesis into a pattern of separate neuronal clusters and might ultimately be necessary to maintain MHB integrity. Her5 appears as a partially redundant component of this inhibitory process that helps translate early axial patterning information into a distinct spatiotemporal pattern of neurogenesis and cell proliferation within the MH domain. AU - Geling, A. AU - Itoh, M.* AU - Tallafuß, A. AU - Chapouton, P. AU - Tannhäuser, B. AU - Kuwada, J.Y.* AU - Chitnis, A.B.* AU - Bally-Cuif, L. C1 - 33164 C2 - 20973 SP - 1591-1604 TI - bHLH transcription factor Her5 links patterning to regional inhibition of neurogenesis at the midbrain-hindbrain boundary. JO - Development VL - 130 IS - 8 PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - We examined the role of Notch signaling on the generation of neurons and glia from neural stem cells by using neurospheres that are clonally derived from neural stem cells. Neurospheres prepared from Dll1lacZ/lacZ mutant embryos segregate more neurons at the expense of both oligodendrocytes and astrocytes. This mutant phenotype could be rescued when Dll1lacZ/lacZ spheres were grown and/or differentiated in the presence of conditioned medium from wild-type neurospheres. Temporal modulation of Notch by soluble forms of ligands indicates that Notch signaling acts in two steps. Initially, it inhibits the neuronal fate while promoting the glial cell fate. In a second step, Notch promotes the differentiation of astrocytes, while inhibiting the differentiation of both neurons and oligodendrocytes. AU - Grandbarbe, L.* AU - Bouissac, J.* AU - Rand, M.* AU - Hrabě de Angelis, M. AU - Artavanis-Tsakonas, S.* AU - Mohier, E.* C1 - 22269 C2 - 21041 SP - 1391-1402 TI - Delta-Notch signaling controls the generation of neurons/glia from neural stem cells in a stepwise process. JO - Development VL - 130 PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - The cerebellum comprises a medial domain, called the vermis, flanked by two lateral subdivisions, the cerebellar hemispheres. Normal development of the vermis involves fusion of two lateral primordia on the dorsal midline. We investigated how the cerebellum fuses on the midline by combining a study of mid/hindbrain cell movements in avian embryos with the analysis of cerebellar fusion in normal and mutant mouse embryos. We found that, in avian embryos, divergent cell movements originating from a restricted medial domain located at the mid/hindbrain boundary produce the roof plate of the mid/hindbrain domain. Cells migrating anteriorly from this region populate the caudal midbrain roof plate whereas cells migrating posteriorly populate the cerebellar roof plate. In addition, the adjacent paramedial isthmic neuroepithelium also migrates caudalward and participates in the formation of the cerebellar midline region. We also found that the paramedial isthmic territory produces two distinct structures. First, the late developing velum medullaris that intervenes between the vermis and the midbrain, and second, a midline domain upon which the cerebellum fuses. Elimination or overgrowth of this isthmic domain in Wnt1sw/sw and En1+/Otx2lacZ mutant mice, respectively, impair cerebellar midline fusion. Because the isthmus-derived midline cerebellar domain displays a distinct expression pattern of genes involved in BMP signaling, we propose that the isthmus-derived cells provide both a substratum and signals that are essential for cerebellar fusion. AU - Louvi, A.* AU - Alexandre, P.* AU - Métin, C.* AU - Wurst, W. AU - Wassef, M.* C1 - 2638 C2 - 22456 SP - 5319-5330 TI - The isthmic neuroepithelium is essential for cerebellar midline fusion. JO - Development VL - 130 IS - 22 PB - Company of Biologists PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - Axes formation is a fundamental process of early embryonic development. In addition to the anteroposterior and dorsoventral axes, the determination of the left-right axis is crucial for the proper morphogenesis of internal organs and is evolutionarily conserved in vertebrates. Genes known to be required for the normal establishment and/or maintenance of left-right asymmetry in vertebrates include, for example, components of the TGF-β family of intercellular signalling molecules and genes required for node and midline function. We report that Notch signalling, which previously had not been implicated in this morphogenetic process, is required for normal left-right determination in mice. We show, that the loss-of-function of the delta 1 (Dll1) gene causes a situs ambiguous phenotype, including randomisation of the direction of heart looping and embryonic turning. The most probable cause for this left-right defect in Dll1 mutant embryos is a failure in the development of proper midline structures. These originate from the node, which is disrupted and deformed in Dll1 mutant embryos. Based on expression analysis in wild-type and mutant embryos, we suggest a model, in which Notch signalling is required for the proper differentiation of node cells and node morphology. AU - Przemeck, G.K.H. AU - Heinzmann, U. AU - Beckers, J. AU - Hrabě de Angelis, M. C1 - 22272 C2 - 21045 SP - 3-13 TI - Node and midline defects are associated with left-right development in Delta1 mutant embryos. JO - Development VL - 130 IS - 1 PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - We have previously shown that the paired-box transcription factors Pax1 and Pax9 synergistically act in the proper formation of the vertebral column. Nevertheless, downstream events of the Pax1/Pax9 action and their target genes remain to be elucidated. We show, by analyzing Pax1;Pax9 double mutant mice, that expression of Bapx1 in the sclerotome requires the presence of Pax1 and Pax9, in a gene dose-dependent manner. By using a retroviral system to overexpress Pax1 in chick presomitic mesoderm explants, we show that Pax1 can substitute for Shh in inducing Bapx1 expression and in initiating chondrogenic differentiation. Furthermore, we demonstrate that Pax1 and Pax9 can transactivate regulatory sequences in the Bapx1 promoter and that they physically interact with the Bapx1 promoter region. These results strongly suggest that Bapx1 is a direct target of Pax1 and Pax9. Together, we conclude that Pax1 and Pax9 are required and sufficient for the chondrogenic differentiation of sclerotomal cells. AU - Rodrigo, I. AU - Hill, R.E.* AU - Balling, R.* AU - Münsterberg, A.* AU - Imai, K. C1 - 10250 C2 - 21182 SP - 473-482 TI - Pax1 and Pax9 activate Bapx1 to induce chondrogenic differentiation in the sclerotome. JO - Development VL - 130 IS - 3 PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - The midbrain-hindbrain domain (MH) of the vertebrate embryonic neural tube develops in response to the isthmic organizer (IsO), located at the midbrain-hindbrain boundary (MHB). MH derivatives are largely missing in mutants affected in IsO activity; however, the potentialities and fate of MH precursors in these conditions have not been directly determined. To follow the dynamics of MH maintenance in vivo, we used artificial chromosome transgenesis in zebrafish to construct lines where egfp transcription is driven by the complete set of regulatory elements of her5, the first known gene expressed in the MH area. In these lines, egfp transcription faithfully recapitulates her5 expression from its induction phase onwards. Using the stability of GFP protein as lineage tracer, we first demonstrate that her5 expression at gastrulation is a selective marker of MH precursor fate. By comparing GFP protein and her5 transcription, we further reveal the spatiotemporal dynamics of her5 expression that conditions neurogenesis progression towards the MHB over time. Finally, we trace the molecular identity of GFP-positive cells in the acerebellar (ace) and no-isthmus (noi) mutant backgrounds to analyze directly fgf8 and pax2.1 mutant gene activities for their ultimate effect on cell fate. We demonstrate that most MH precursors are maintained in both mutants but express abnormal identities, in a manner that strikingly differs between the ace and noi contexts. Our observations directly support a role for Fgf8 in protecting anterior tectal and metencephalic precursors from acquiring anterior identities, while Pax2.1 controls the choice of MH identity as a whole. Together, our results suggest a model where an ordered MH pro-domain is identified at gastrulation, and where cell identity choices within this domain are subsequently differentially controlled by Fgf8 and Pax2.1 functions. AU - Tallafuß, A.* AU - Bally-Cuif, L. C1 - 22280 C2 - 21060 SP - 4307-4323 TI - Tracing of her5 progeny in zebrafish transgenics reveals the dynamics of midbrain-hindbrain neurogenesis and maintenance. JO - Development VL - 130 PY - 2003 SN - 0950-1991 ER - TY - JOUR AB - N-cadherin (Ncad) is a classical cadherin that is implicated in several aspects of vertebrate embryonic development, including somitogenesis, heart morphogenesis, neural tube formation and establishment of left-right asymmetry. However, genetic in vivo analyses of its role during neural development have been rather limited. We report the isolation and characterization of the zebrafish parachute (pac) mutations. By mapping and candidate gene analysis, we demonstrate that pac corresponds to a zebrafish n-cadherin (ncad) homolog. Three mutant alleles were sequenced and each is likely to encode a non-functional Ncad protein. All result in a similar neural tube phenotype that is most prominent in the midbrain, hindbrain and the posterior spinal cord. Neuroectodermal cell adhesion is altered, and convergent cell movements during neurulation are severely compromised. In addition, many neurons become progressively displaced along the dorsoventral and the anteroposterior axes. At the cellular level, loss of Ncad affects β-catenin stabilization/localization and causes mispositioned and increased mitoses in the dorsal midbrain and hindbrain, a phenotype later correlated with enhanced apoptosis and the appearance of ectopic neurons in these areas. Our results thus highlight novel and crucial in vivo roles for Ncad in the control of cell convergence, maintenance of neuronal positioning and dorsal cell proliferation during vertebrate neural tube development. AU - Lele, Z.* AU - Folchert, A. AU - Concha, M.* AU - Rauch, G.-J.* AU - Geisler, R.* AU - Rosa, F.* AU - Wilson, S.W.* AU - Hammerschmidt, M* AU - Bally-Cuif, L. C1 - 10249 C2 - 20766 SP - 3281-3294 TI - Parachute/n-cadherin is required for morphogenesis and maintained integrity of the zebrafish neural tube. JO - Development VL - 129 PY - 2002 SN - 0950-1991 ER - TY - JOUR AB - The thyroid gland is an organ primarily composed of endoderm-derived follicular cells. Although disturbed embryonic development of the thyroid gland leads to congenital hypothyroidism in humans and mammals, the underlying principles of thyroid organogenesis are largely unknown. In this study, we introduce zebrafish as a model to investigate the molecular and genetic mechanisms that control thyroid development. Marker gene expression suggests that the molecular pathways of early thyroid development are essentially conserved between fish and mammals. However during larval stages, we find both conserved and divergent features of development compared with mammals. A major difference is that in fish, we find evidence for hormone production not only in thyroid follicular cells, but also in an anterior non-follicular group of cells.We show that pax2.1 and pax8, members of the zebrafish pax2/5/8 paralogue group, are expressed in the thyroid primordium. Whereas in mice, only Pax8 has a function during thyroid development, analysis of the zebrafish pax2.1 mutant no isthmus (noi(-/-)) demonstrates that pax2.1 has a role comparable with mouse Pax8 in differentiation of the thyroid follicular cells. Early steps of thyroid development are normal in noi(-/-), but later expression of molecular markers is lost and the formation of follicles fails. Interestingly, the anterior non-follicular site of thyroid hormone production is not affected in noi(-/-). Thus, in zebrafish, some remaining thyroid hormone synthesis takes place independent of the pathway leading to thyroid follicle formation. We suggest that the noi(-/-) mutant serves as a new zebrafish model for hypothyroidism. AU - Wendel, T.* AU - Lun, K.* AU - Mione, M.* AU - Favor, J. AU - Brand, M.* AU - Wilson, S.W.* AU - Rohr, K.B.* C1 - 10248 C2 - 20430 SP - 3751-3760 TI - Development and Disease : pax2.1 is required for the development of thyroid follicles in zebrafish. JO - Development VL - 129 IS - 15 PB - Company of Biologists PY - 2002 SN - 0950-1991 ER - TY - JOUR AB - Notch signaling has a central role in cell fate specification and differentiation. We provide evidence that the Mash1 (bHLH) and Dlx1 and Dlx2 (homeobox) transcription factors have complementary roles in regulating Notch signaling, which in turn mediates the temporal control of subcortical telencephalic neurogenesis in mice. We defined progressively more mature subcortical progenitors (P1, P2 and P3) through their combinatorial expression of MASH1 and DLX2, as well as the expression of proliferative and postmitotic cell markers at E10.5-E11.5. In the absence of Mash1, Notch signaling is greatly reduced and `early' VZ progenitors (P1 and P2) precociously acquire SVZ progenitor (P3) properties. Comparing the molecular phenotypes of the delta-like 1 and Mash1 mutants, suggests that Mash1 regulates early neurogenesis through Notch-and Delta-dependent and -independent mechanisms. While Mash1 is required for early neurogenesis (E10.5), Dlx1 and Dlx2 are required to downregulate Notch signaling during specification and differentiation steps of `late' progenitors (P3). We suggest that alternate cell fate choices in the developing telencephalon are controlled by coordinated functions of bHLH and homeobox transcription factors through their differential affects on Notch signaling. AU - Yun, K.* AU - Fischmann, S.* AU - Johnson, J.* AU - Hrabě de Angelis, M. AU - Weinmaster, G.* AU - Rubenstein, J.L.R.* C1 - 22320 C2 - 21141 SP - 5029-5040 TI - Modulation of the notch signaling by Mash1 and DIx1/2 regulates sequential specification and differentiation of progenitor cell types in the subcortical telencephalon. JO - Development VL - 129 IS - 21 PY - 2002 SN - 0950-1991 ER - TY - JOUR AB - We have investigated the role of the Eph family of receptor tyrosine kinases and their ligands in the establishment of the vomeronasal projection in the mouse. Our data show intriguing differential expression patterns of ephrin-A5 on vomeronasal axons and of EphA6 in the accessory olfactory bulb (AOB), such that axons with high ligand concentration project onto regions of the AOB with high receptor concentration and vice versa. These data suggest a mechanism for development of this projection that is the opposite of the repellent interaction between Eph receptors and ligands observed in other systems. In support of this idea, when given the choice of whether to grow on lanes containing EphA-F(c)/laminin or F(c)/laminin protein (in the stripe assay), vomeronasal axons prefer to grow on EphA-F(c)/laminin. Analysis of ephrin-A5 mutant mice revealed a disturbance of the topographic targeting of vomeronasal axons to the AOB. In summary, these data, which are derived from in vitro and in vivo experiments, indicate an important role of the EphA family in setting up the vomeronasal projection. AU - Knöll, B.* AU - Zarbalis, K.* AU - Wurst, W. AU - Drescher, U.* C1 - 1875 C2 - 22816 SP - 895-906 TI - A role for the EphA in the topographic of vomeronasal axons. JO - Development VL - 128 PB - Company of Biologists PY - 2001 SN - 0950-1991 ER - TY - JOUR AB - Little is known about the factors that control the specification of the mid-hindbrain domain (MHD) within the vertebrate embryonic neural plate. Because the head-trunk junction of the Drosophila embryo and the MHD have patterning similarities, we have searched for vertebrate genes related to the Drosophila head gap gene buttonhead (btd), which in the fly specifies the head-trunk junction. We report here the identification of a zebrafish gene which, like btd, encodes a zinc-finger transcriptional activator of the Sp-1 family (hence its name, bts1 for btd/Sp-related-1) and shows a restricted expression in the head. During zebrafish gastrulation, bts1 is transcribed in the posterior epiblast including the presumptive MHD, and precedes in this area the expression of other MHD markers such as her5, pax2.1 and wnt1. Ectopic expression of bts1 combined to knock-down experiments demonstrate that Bts1 is both necessary and sufficient for the induction of pax2.1 within the anterior neural plate, but is not involved in regulating her5, wnt1 or fgf8 expression. Our results confirm that early MHD development involves several genetic cascades that independently lead to the induction of MHD markers, and identify Bts1 as a crucial upstream component of the pathway selectively leading to pax2.1 induction. In addition, they imply that flies and vertebrates, to control the development of a boundary embryonic region, have probably co-opted a similar strategy: the restriction to this territory of the expression of a Btd/Sp-like factor. AU - Tallafuß, A.* AU - Wilm, T.P. AU - Crozatier, M.* AU - Pfeffer, P.* AU - Wassef, M.* AU - Bally-Cuif, L. C1 - 10247 C2 - 22572 SP - 4021-4034 TI - The zebrafish buttonhead-like factor Bts1 is an early regulator of pax2.1 expression during mid-hindbrain development. JO - Development VL - 128 PY - 2001 SN - 0950-1991 ER - TY - JOUR AB - Somitic segmentation provides the framework on which the segmental pattern of the vertebrae, some muscles and the peripheral nervous system is established. Recent evidence indicates that a molecular oscillator, the ‘segmentation clock’, operates in the presomitic mesoderm (PSM) to direct periodic expression of c-hairy1 and lunatic fringe (l-fng). Here, we report the identification and characterisation of a second avian hairy-related gene, c-hairy2, which also cycles in the PSM and whose sequence is closely related to the mammalian HES1 gene, a downstream target of Notch signalling in vertebrates. We show that HES1 mRNA is also expressed in a cyclic fashion in the mouse PSM, similar to that observed for c-hairy1 and c-hairy2 in the chick. In HES1 mutant mouse embryos, the periodic expression of l-fng is maintained, suggesting that HES1 is not a critical component of the oscillator mechanism. In contrast, dynamic HES1 expression is lost in mice mutant for Delta1, which are defective for Notch signalling. These results suggest that Notch signalling is required for hairy-like genes cyclic expression in the PSM. AU - Jouve, C.* AU - Palmeirim, I.* AU - Henrique, D.* AU - Beckers, J. AU - Gossler, A.* AU - Ish-Horowicz, D.* AU - Pourquie, O.* C1 - 22304 C2 - 21110 SP - 1421-1429 TI - Notch signalling is required for cyclic expression of the hairy-like gene HES1 in the presomitic mesoderm. JO - Development VL - 127 PY - 2000 SN - 0950-1991 ER - TY - JOUR AB - Pax1 is a transcriptional regulatory protein expressed during mouse embryogenesis and has been shown to have an important function in vertebral column development. Expression of Pax1 mRNA in the embryonic thymus has been reported previously. Here we show that Pax1 protein expression in thymic epithelial cells can be detected throughout thymic development and in the adult. Expression starts in the early endodermal epithelium lining the foregut region and includes the epithelium of the third pharyngeal pouch, a structure giving rise to part of the thymus epithelium. In early stages of thymus development a large proportion of thymus cells expresses Pax1. With increasing age, the proportion of Pax1-expressing cells is reduced and in the adult mouse only a small fraction of cortical thymic stromal cells retains strong Pax1 expression. Expression of Pax1 in thymus epithelium is necessary for establishing the thymus microenvironment required for normal T cell maturation. Mutations in the Pax-1 gene in undulated mice affect not only the total size of the thymus but also the maturation of thymocytes. The number of thymocytes is reduced about 2- to 5-fold, affecting mainly the CD4+8+ immature and CD4+ mature thymocyte subsets. The expression levels of major thymocyte surface markers remains unchanged with the exception of Thy-1 which was found to be expressed at 3- to 4-fold higher levels. AU - Wallin, J.E.* AU - Eibel, H.* AU - Neubüser, A.* AU - Wilting, J.* AU - Koseki, H.* AU - Balling, R. C1 - 33217 C2 - 35614 SP - 23-30 TI - Pax1 is expressed during development of the thymus epithelium and is required for normal T-cell maturation. JO - Development VL - 122 IS - 1 PY - 1996 SN - 0950-1991 ER - TY - JOUR AU - Graw, J. AU - Liebstein, A. C1 - 19815 C2 - 12964 TI - Developmentally Regulated Expression of a Novel Murine DNase in Early Postnatal Lenses and its Inhibition in Dominant Cataract Mutants. JO - Development PY - 1991 SN - 0950-1991 ER - TY - JOUR AU - Schwefel, D. AU - Leidl, R. C1 - 17237 C2 - 10203 SP - 142-144 TI - Remarks on the social Meaning of Savings of the Poor. JO - Development VL - 2/3 PY - 1987 SN - 0950-1991 ER -