TY  - JOUR
AB  - Cilia play a major role in the regulation of numerous signaling pathways and are essential for embryonic development. Mutations in genes affecting ciliary function can cause a variety of diseases in humans summarized as ciliopathies. To facilitate the detection and visualization of cilia in a temporal and spatial manner in mouse tissues, we generated a Cre-inducible cilium-specific reporter mouse line expressing an ARL13B-tRFP fusion protein driven by a CMV enhancer/chicken β actin promotor (pCAG) from the Hprt locus. We detected bright and specific ciliary signals by immunostainings of various mono- and multiciliated tissues and by time-lapse live-cell analysis of cultured embryos and organ explant cultures. Additionally, we monitored cilium assembly and disassembly in embryonic fibroblast cells using live-cell imaging. Thus, the ARL13B-tRFP reporter mouse strain is a valuable tool for the investigation of ciliary structure and function in a tissue-specific manner to understand processes, such as ciliary protein trafficking or cilium-dependent signaling in vitro and in vivo.
AU  - Schmitz, F.
AU  - Burtscher, I.
AU  - Stauber, M.*
AU  - Gossler, A.*
AU  - Lickert, H.
C1  - 52164
C2  - 43745
CY  - Hoboken
TI  - A novel Cre-inducible knock-in ARL13B-tRFP fusion cilium reporter.
JO  - Genesis
VL  - 55
IS  - 11
PB  - Wiley
PY  - 2017
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - The Foxa2-winged helix/forkhead box transcription factor (TF) is absolutely required for endoderm formation and organogenesis. Foxa2 plays essential roles during lung, liver, pancreas, and gastrointestinal tract development and regulates cell-type specific programs in the adult organism. To specifically address Foxa2 function during organ development and homeostasis, we generated a Foxa2-Venus fusion (FVF) reporter protein by gene targeting in embryonic stem (ES) cells. The FVF knock-in reporter is expressed under endogenous Foxa2 control and the fluorescent protein fusion does not interfere with TF function, as homozygous mice are viable and fertile. Moreover, the FVF protein localizes to the nucleus, associates with chromatin during mitosis, and reflects the endogenous Foxa2 protein distribution pattern in several tissues in heterozygous animals. Importantly, live-cell imaging on single-cell level of the FVF and Sox17-Cherry fusion double knock-in reporter ES cell line reveals the dynamics of endoderm TF accumulation during ES cell differentiation. The FVF reporter also allowed us to identify the endoderm progenitors during gastrulation and to visualize the different branching morphogenesis modes of the lung and pancreas epithelium in ex vivo embryo and organ cultures. In summary, the generation of the FVF reporter line adds an important new tool to visualize and analyse endoderm-derived organ development and homeostasis on the cellular and molecular level.
AU  - Burtscher, I.
AU  - Barkey, W.
AU  - Lickert, H.
C1  - 26088
C2  - 32063
SP  - 596-604
TI  - Foxa2-venus fusion reporter mouse line allows live-cell analysis of endoderm-derived organ formation.
JO  - Genesis
VL  - 51
IS  - 8
PB  - Wiley-Blackwell
PY  - 2013
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - The HMG-box transcription factor Sox17 is essential for endoderm formation, vascular development, and definitive hematopoiesis. To investigate the fate of distinct Sox17-expressing progenitor cells in a spatiotemporal manner, we generated a hormone-inducible CreERT2 knock-in mouse line. By homologous recombination we fused a codon improved, ligand-dependent estrogen receptor Cre recombinase by an intervening viral T2A sequence for co-translational cleavage to the 3' coding region of Sox17. Induction of Cre activity by administration of tamoxifen at defined time points of early mouse development and subsequent genetic lineage tracing confirmed the inducibility and tissue specificity of Cre recombination. Furthermore, Cre activity could be selectively induced in extra-embryonic and embryonic endoderm lineages, the primitive gut tube, and in endothelial cells of the vascular system as well as in the hemogenic endothelium of the dorsal aorta. The Sox17CreERT2 mouse line therefore represents a new tool for genetic lineage tracing in a tissue-specific manner and in addition enables lineage-restricted functional analysis.
AU  - Engert, S.
AU  - Burtscher, I.
AU  - Kalali, B.*
AU  - Gerhard, M.*
AU  - Lickert, H.
C1  - 27760
C2  - 32800
SP  - 793-802
TI  - The Sox17CreERT2 knock-in mouse line displays spatiotemporal activation of Cre recombinase in distinct Sox17 lineage progenitors.
JO  - Genesis
VL  - 51
IS  - 11
PB  - Wiley
PY  - 2013
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Deregulated MAP kinase (MAPK) signaling plays key roles in developmental and adult disease processes, but the experimental activation of MAPK is a currently unresolved task. For the reversible induction of MAPK signaling, we generated transgenic mice harboring a tamoxifen inducible BRAF(V637E) ER(T2) fusion protein. The expression of the inducible BRAF kinase can be directed by Cre/loxP-mediated recombination to selected cell types and enables the highly specific activation of MAPK signalling in vivo. We show that MAPK signaling can be transiently activated in the brain, liver, or kidney of Braf(V637E) ER(T2) mice by a single injection of tamoxifen. Braf(V637E) ER(T2) mice provide a new versatile tool to study disease mechanisms elicited by MAPK activation, complementing gene knockout technology that is restricted to the analysis of loss-of-function phenotypes. genesis 1-8.
AU  - Ortiz, O.
AU  - Wurst, W.
AU  - Kühn, R.
C1  - 24364
C2  - 31506
SP  - 448-455
TI  - Reversible and tissue-specific activation of MAP kinase signaling by tamoxifen in brafV637 ERT2 mice.
JO  - Genesis
VL  - 51
IS  - 6
PB  - Wiley-Blackwell
PY  - 2013
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Sox17 is a HMG-box transcription factor that has been shown to play important roles in both cardio-vascular development and endoderm formation. To analyze these processes in greater detail, we have generated a Sox17-mCherry fusion (SCF) protein by gene targeting in ES cells. SCF reporter mice are homozygous viable and faithfully reflect the endogenous Sox17 protein localization. We report that SCF positive cells constitute a subpopulation in the visceral endoderm before gastrulation and time-lapse imaging reveals that SCF monitors the nascent definitive endoderm during epithelialisation. After gastrulation, SCF marks the mid- and hindgut endoderm and vascular endothelial network, which can be imaged during establishment in allantois explant cultures. The SCF reporter is downregulated in the endoderm epithelium and upregulated in endothelial cells of the intestine, lung and pancreas during organogenesis. In summary, the generation of the Sox17-mCherry reporter mouse line allows direct visualization of endoderm and vascular development in culture and the mouse embryo.
AU  - Burtscher, I.
AU  - Barkey, W.
AU  - Schwarzfischer, M.
AU  - Theis, F.J.
AU  - Lickert, H.
C1  - 6799
C2  - 29283
SP  - 496-505
TI  - The Sox17-mCherry fusion mouse line allows visualization of endoderm and vascular endothelial development.
JO  - Genesis
VL  - 50
IS  - 6
PB  - Wiley-Blackwell
PY  - 2012
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - SOX10 is a well-conserved and widely expressed transcription factor involved in the regulation of embryonic development and in the determination of cell fate. As it is expressed in neural crest cells, their derivatives and the oligodendrocyte lineage, mutations of the protein contribute to a variety of diseases like neurocristopathies, peripheral demyelinating neuropathies and melanoma. Here, we report the generation of an inducible Sox10-iCreER(T2) BAC transgenic mouse line that labels, depending on the timepoint of induction, distinct derivatives of the otic placode and the neural crest as well as cells of the oligodendrocyte lineage. Surprisingly, we could show a neural crest origin of pericytes in the brain. Besides its use for fate-mapping, the Sox10-iCreER(T2) mouse line is a powerful tool to conditionally inactivate genes in the neural crest cells, its progeny and/or the oligodendrocyte lineage in a time-dependent fashion to gain further insights into their function and contribution to diseases.
AU  - Simon, C.
AU  - Lickert, H.
AU  - Götz, M.
AU  - Dimou, L.
C1  - 6801
C2  - 29285
SP  - 506-515
TI  - Sox10-iCreERT2 : A mouse line to inducibly trace the neural crest and oligodendrocyte lineage.
JO  - Genesis
VL  - 50
IS  - 6
PB  - Wiley-Blackwell
PY  - 2012
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Sox17 encodes an SRY-related high-mobility group (HIVIG) box transcription factor that is essential for endoderm formation and fetal hematopoietic stem cell maintenance. In the mouse, expression of Sox17 is first observed in the extraembryonic endoderm and is subsequently seen in the definitive endoderm as well as in blood and the endothelial cells of the developing vasculature. To conditionally inactivate genes in these domains, we have targeted the Sox17 locus to generate a bicistronic mRNA linking Sox17 to a codon improved Cre recombinase (iCre) via a viral 2A sequence. Here we report a new Cre knock-in mouse line, Sox17-2A-iCre, with activity in the developing endoderm, the vascular endothelial cells of the cardiovascular system and the hematopoietic system. Our results indicate that the Sox17-2A-iCre is active in an early endoderm progenitor and recombination of the Rosa26 reporter was observed in all previously reported expression domains of Sox17. The Sox17-2A-iCre line will be an excellent tool to conditionally inactivate genes in the definitive endoderm as well as in the vasculature and hematopoietic system.
AU  - Engert, S.
AU  - Liao, W.P.
AU  - Burtscher, I.
AU  - Lickert, H.
C1  - 1627
C2  - 26587
CY  - Hoboken
SP  - 603-610
TI  - Sox17-2A-iCre: A knock-in mouse line expressing Cre recombinase in endoderm and vascular endothelial cells.
JO  - Genesis
VL  - 47
IS  - 9
PB  - Wiley-Blackwell
PY  - 2009
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - The HMG-box transcription factor Sox17 has been shown to play important roles in both endoderm formation and cardiovascular development. To conditionally inactivate genes in these domains, we have targeted a codon improved Cre Recombinase (iCre) into exon 1 of the Sox17 gene. Surprisingly, Cre-mediated recombination in the Rosa26 reporter mouse line revealed largely specific activity within the vasculature rather than in endoderm-derived tissues. Here we report a new Cre knock-in mouse line, Sox17(iCre) with activity in the vascular endothelial cells of arteries in the cardiovascular system but not in veins. Cre-mediated recombination was also strongly detected in the liver and spleen, the two organs associated with hematopoiesis. Thus, these results indicate that the Sox17(iCre) would be an appropriate tool for conditional mutagenesis of genes in the vasculature and could be used in studies of blood vessel development and angiogenesis. Additionally, we provide evidence that two different promoters drive Sox17 expression in the endodermal and vascular system.
AU  - Liao, W.P.
AU  - Uetzmann, L.
AU  - Burtscher, I.
AU  - Lickert, H.
C1  - 738
C2  - 26364
SP  - 476-483
TI  - Generation of a mouse line expressing Sox17-driven Cre recombinase with specific activity in arteries.
JO  - Genesis
VL  - 47
IS  - 7
PB  - Wiley-Blackwell
PY  - 2009
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Periphilin is involved in multiple processes in vivo. To explore its physiological role from an organismic perspective, we generated mice with a gene trap insertion in the periphilin-1 gene. Based on beta-gal reporter activity, a widespread periphilin expression was evident, especially in the developing somites and limbs, the embryonic nervous system, and the adult brain. In accordance with this broad expression, homozygous deficiency of periphilin was lethal in early embryogenesis. Mice with a heterozygous deficiency did not show any abnormalities of brain morphology and function, neither histologically nor regarding the transcriptome. Interestingly, the reduction of the periphilin-1 gene dosage was compensated by an increased expression of the remaining wild-type allele in the brain. These results point to an indispensable function of periphilin during murine development and an important role in the nervous system, reflected by a strong and tightly regulated expression in the murine brain.
AU  - Soehn, A.S.*
AU  - Pham, T.T.
AU  - Schaeferhoff, K.*
AU  - Floß, T.
AU  - Vogt Weisenhorn, D.M.
AU  - Wurst, W.
AU  - Bonin, M.*
AU  - Riess, O.*
C1  - 585
C2  - 26372
CY  - Hoboken
SP  - 697-707
TI  - Periphilin is strongly expressed in the murine nervous system and is indispensable for murine development.
JO  - Genesis
VL  - 47
IS  - 10
PB  - Wiley-Blackwell
PY  - 2009
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Taking advantage of a mutant estrogen receptor ligand binding domain (ER(T2)), we developed novel Caspase fusion proteins for inducible apoptosis. We show that Caspase-ER(T2) fusion proteins become specifically activated by the synthetic ligand 4-OH- tamoxifen and rapidly induce apoptotic cell death in human, murine, and zebrafish cells. This novel tool for targeted cell ablation greatly facilitates the generation of disease models as well as developmental and regeneration studies in model organisms.
AU  - Chu, Y.
AU  - Senghaas, N.
AU  - Köster, R.W.
AU  - Wurst, W.
AU  - Kühn, R.
C1  - 2560
C2  - 25798
SP  - 530-536
TI  - Novel caspase-suicide proteins for tamoxifen-inducible apoptosis.
JO  - Genesis
VL  - 46
IS  - 10
PB  - Wiley-Blackwell
PY  - 2008
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - One of the most promising techniques to manipulate gene expression in vivo is the use of RNA interference (RNAi). Various approaches were developed to use RNAi in the mouse, including vector-based expression of short hairpin RNAs and the Cre/loxP recombination system. We combined these two approaches to create a vector system that allows the time- and tissue-specific control of two genes at the same time. For this purpose two independent conditional shRNA expression cassettes are combined into a single construct. By the use of different, incompatible pairs of lox sites that flank transcriptional stop cassettes, Cre recombinase can independently activate both short hairpins. Here, we show that Cre simultaneously activates both shRNAs in vitro and in vivo. We applied this technique to silence the widely coexpressed gene pairs Gsk-3 alpha/Gsk-3 beta and Erk1/Erk2 in murine embryonic stem cells and in the mouse brain.
AU  - Steuber-Buchberger, P.M.
AU  - Wurst, W.
AU  - Kühn, R.
C1  - 1857
C2  - 25888
SP  - 144-151
TI  - Simultaneous Cre-mediated conditional knockdown of two genes in mice.
JO  - Genesis
VL  - 46
IS  - 3
PB  - Wiley-Blackwell
PY  - 2008
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Foxa2 is a forkhead transcription factor expressed in the node, notochord, floorplate, and definitive endoderm and is required in the foregut endoderm for the normal development of the endoderm-derived organs, such as the liver, lung and pancreas. To conditionally inactivate genes in these tissues and organs, we have targeted a Cre recombinase into Exon 1 of the Foxa2 gene. We show, upon crossing to the ROSA26 reporter mice, that Cre expression from the Foxa2(iCre) knock-in allele specifically activates beta-galactosidase expression in the node, notochord, floorplate, and endoderm. In addition, we detect Cre recombination activity in the endoderm-derived organs including lung, liver, pancreas, and gastrointestinal tract throughout development. These results demonstrate that the Foxa2(iCre) knock-in mice are a valuable tool to analyze gene function in endoderm progenitors and endoderm-derived organs. Moreover, the widespread beta-galactosidase reporter activity in the endoderm suggests that Foxa2 marks a progenitor cell population, which gives rise to the majority of cells in endoderm-derived organs.
AU  - Uetzmann, L.
AU  - Burtscher, I.
AU  - Lickert, H.
C1  - 3644
C2  - 25664
SP  - 515-522
TI  - A mouse line expressing Foxa2-driven Cre recombinase in node, notochord, floorplate, and endoderm.
JO  - Genesis
VL  - 46
IS  - 10
PB  - Wiley-Blackwell
PY  - 2008
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Reciprocal signals from embryonic and extra-embryonic tissues pattern the embryo in proximal-distal (PD) and anterior-posterior (AP) fashion. Here we have analyzed three gene trap mutations of Sall4, of which one (Sall4-1a) led to a hypomorphic and recessive phenotype, demonstrating that Sall4-1a has yet undescribed extra-embryonic and embryonic functions in regulating PD and AP axis formation. In Sall4-1a mutants the self-maintaining autoregulatory interaction between Bmp4, Nodal and Wnt, which determines the PD axis was disrupted because of defects in the extra-embryonic visceral endoderm. More severely, two distinct Sall4 gene-trap mutants (Sall4-1a,b), resembling null mutants, failed to initiate Bmp4 expression in the extra-embryonic ectoderm and Nodal in the epiblast and were therefore unable to initiate PD axis formation. Tetraploid rescue underlined the extra-embryonic nature of the Sall4-1a phenotype and revealed a further embryonic function in Wnt/beta-catenin signaling to elongate the AP axis during gastrulation. This observation was supported through genetic interaction with beta-catenin mutants, since compound heterozygous mutants recapitulated the defects of Wnt3a mutants in posterior development.
AU  - Uez, N.
AU  - Lickert, H.
AU  - Kohlhase, J.*
AU  - Hrabě de Angelis, M.
AU  - Kühn, R.
AU  - Wurst, W.
AU  - Floß, T.
C1  - 4292
C2  - 25551
SP  - 463-477
TI  - Sall4 isoforms act during proximal-distal and anterior-posterior axis formation in the mouse embryo.
JO  - Genesis
VL  - 46
IS  - 9
PB  - Wiley-Blackwell
PY  - 2008
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Inducible and tissue-specific gene inactivation in mice has become a powerful tool to bypass embryonic and postnatal lethality of knockout mice. The most frequently used inducible system is based on Cre recombinase fused to either one or two mutated estrogen receptor ligand binding domains, thus rendering Cre function tamoxifen-dependent. To achieve Cre-mediated inactivation of a given gene, 4-OH tamoxifen (4-OHT) dissolved either in alcohol and/or oil is usually administered by repeated intraperitoneal (i.p.) injections. Since this procedure imposes considerable stress on mice, we compared the effect of tamoxifen citrate, mixed into a standard mouse diet at different concentrations, with that of i.p. administration of 4-OHT on Cre-mediated, heart-specific inactivation of thioredoxin reductase 2. Here we show that tamoxifen citrate in the chow was equally effective as 4-OHT given i.p. Oral tamoxifen administration is thus a convenient and cost-saving way for gene induction, and, most importantly, it reduces stress and avoids adverse effects in mice.
AU  - Kiermayer, C.
AU  - Conrad, M.
AU  - Schneider, M.
AU  - Schmidt, J.
AU  - Brielmeier, M.
C1  - 3597
C2  - 24707
SP  - 11-16
TI  - Optimization of spatiotemporal gene inactivation in mouse heart by oral application of tamoxifen citrate.
JO  - Genesis
VL  - 45
IS  - 1
PB  - Wiley-Blackwell
PY  - 2007
SN  - 1526-954X
ER  - 

TY  - JOUR
AB  - Mib1 and Mib2 ubiquitin ligases are very similar in their domain construction. They partake in the Notch signaling pathway by ubiquitinating the Notch receptors Delta and Jagged prior to endocytosis. We have created a targeted mutation of Mib2 and show that its phenotype is a variable penetrance, failure to close the cranial neural tube. The penetrance depends on the genetic background but it appears that Mib2 is not completely essential in mouse development.
AU  - Wu, J.I.*
AU  - Rajendra, R.
AU  - Barsi, J.C.*
AU  - Durfee, L.*
AU  - Benito, E . *
AU  - Gao, G.*
AU  - Kuruvilla, M.*
AU  - Hrdlicková, R.*
AU  - Liss, A.S.*
AU  - Artzt, K.*
C1  - 4767
C2  - 24889
SP  - 722-727
TI  - Targeted disruption of Mib2 causes exencephaly with a variable penetrance.
JO  - Genesis
VL  - 45
IS  - 11
PB  - Wiley-Blackwell
PY  - 2007
SN  - 1526-954X
ER  - 

TY  - JOUR
AU  - Hitz, C.
AU  - Vogt Weisenhorn, D.M.
AU  - Ruiz, P.*
AU  - Wurst, W.
AU  - Floß, T.
C1  - 1118
C2  - 22744
SP  - 91-103
TI  - Progressive loss of the spongiotrophoblast layer of Birc6/Bruce mutants results in embryonic lethality.
JO  - Genesis
VL  - 42
PB  - Wiley
PY  - 2005
SN  - 1526-954X
ER  - 

TY  - JOUR
AU  - Ming Kwan, K.*
AU  - Li, A.G.*
AU  - Wang, X.-J.*
AU  - Wurst, W.
AU  - Behringer, R.R.*
C1  - 5339
C2  - 22669
SP  - 10-25
TI  - Essential roles of BMPR-IA signaling in differentiation and growth of hair follicles and in skin tumorigenesis.
JO  - Genesis
VL  - 39
PB  - Wiley
PY  - 2004
SN  - 1526-954X
ER  -