TY - JOUR AB - White adipose tissue (WAT) comprises a plethora of cell types beyond adipocytes forming a regulatory network that ensures systemic energy homeostasis. Intertissue communication is facilitated by metabolites and signaling molecules that are spread by vasculature and nerves. Previous works indicated that WAT responds to environmental cues by adapting the abundance of these "communication routes", however, high intra-tissue heterogeneity questions the informative value of bulk or single cell analyses and underscores the necessity of whole-mount imaging. The applicability of whole-mount WAT-imaging is currently limited by two factors: I) Methanol-based tissue clearing protocols restrict the usable antibody portfolio to methanol resistant antibodies and II) The vast amounts of data resulting from 3D imaging of whole-tissue samples require high computational expertise and advanced equipment. Here, we present a protocol for whole-mount WAT clearing, overcoming the constraints of antibody-methanol sensitivity. Additionally, we introduce TiNeQuant (Tissue Network Quantifier) a Fiji tool for automated 3D quantification of neuron- or vascular network density, freely available at https://github.com/SchweigerLab/TiNeQuant. Given TiNeQuants versatility beyond WAT, it simplifies future efforts studying neuronal or vascular alterations in numerous pathologies. AU - Rauchenwald, T.* AU - Benedikt-Kühnast, P. AU - Eder, S.* AU - Grabner, G.F.* AU - Forstreiter, S.* AU - Lang, M.* AU - Sango, R.* AU - Eisenberg, T.* AU - Rattei, T.* AU - Haschemi, A.* AU - Wolinski, H.* AU - Schweiger, M.* C1 - 73214 C2 - 56963 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Clearing the path for whole-mount labeling and quantification of neuron- and vessel-density in adipose tissue. JO - J. Cell Sci. VL - 138 IS - 3 PB - Company Biologists Ltd PY - 2025 SN - 0021-9533 ER - TY - JOUR AU - Canat, A. C1 - 68924 C2 - 53676 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - First person – Antoine Canat. JO - J. Cell Sci. VL - 136 IS - 19 PB - Company Biologists Ltd PY - 2023 SN - 0021-9533 ER - TY - JOUR AB - In April 2022, The Company of Biologists hosted their first post-pandemic in-person Workshop at Buxted Park Country House in the Sussex countryside. The Workshop, entitled 'Cell size and growth: from single cells to the tree of life', gathered a small group of early-career and senior researchers with expertise in cell size spanning a broad range of organisms, including bacteria, yeast, animal cells, embryos and plants, and working in fields from cell biology to ecology and evolutionary biology. The programme made ample room for fruitful discussions and provided a much-needed opportunity to discuss the most recent findings relating to the regulation of cell size and growth, identify the emerging challenges for the field, and build a community after the pandemic. AU - Chatzitheodoridou, D.* AU - D'Ario, M.* AU - Jones, I.* AU - Piñeros, L.* AU - Serbanescu, D.* AU - O'Donnell, F.* AU - Cadart, C.* AU - Swaffer, M.P.* C1 - 66478 C2 - 53187 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Meeting report - Cell size and growth: from single cells to the tree of life. JO - J. Cell Sci. VL - 135 IS - 20 PB - Company Biologists Ltd PY - 2022 SN - 0021-9533 ER - TY - JOUR AU - Gillani, S.Q. C1 - 64446 C2 - 52220 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - First person - Syed Qaaifah Gillani. JO - J. Cell Sci. VL - 135 IS - 3 PB - Company Biologists Ltd PY - 2022 SN - 0021-9533 ER - TY - JOUR AB - Liver cancers, including hepatocellular carcinoma (HCC), are the second leading cause of cancer death worldwide, and novel therapeutic strategies are still highly needed. Recently, the endolysosomal cation channel TRPML1 (also known as MCOLN1) has gained focus in cancer research because it represents an interesting novel target. We utilized the recently developed isoform-selective TRPML1 activator ML1-SA1 and the CRISPR/Cas9 system to generate tools for overactivation and loss-of-function studies on TRPML1 in HCC. After verification of our tools, we investigated the role of TRPML1 in HCC by studying proliferation, apoptosis and proteomic alterations. Furthermore, we analyzed mitochondrial function in detail by performing confocal and transmission electron microscopy combined with SeahorseTM and Oroboros® functional analysis. We report that TRPML1 overactivation mediated by a novel, isoform-selective small-molecule activator induces apoptosis by impairing mitochondrial function in a Ca2+-dependent manner. Additionally, TRPML1 loss-of-function deregulates mitochondrial renewal, which leads to proliferation impairment. Thus, our study reveals a novel role for TRPML1 as regulator of mitochondrial function and its modulators as promising molecules for novel therapeutic options in HCC therapy. AU - Siow, W.X.* AU - Kabiri, Y.* AU - Tang, R.* AU - Chao, Y.K.* AU - Plesch, E.* AU - Eberhagen, C. AU - Flenkenthaler, F.* AU - Fröhlich, T.* AU - Bracher, F.* AU - Grimm, C.* AU - Biel, M.* AU - Zischka, H. AU - Vollmar, A.M.* AU - Bartel, K.* C1 - 64648 C2 - 52369 TI - Lysosomal TRPML1 regulates mitochondrial function in hepatocellular carcinoma cells. JO - J. Cell Sci. VL - 135 IS - 6 PY - 2022 SN - 0021-9533 ER - TY - JOUR AB - Tumour necrosis factor receptors (TNF-Rs) and their ligands, tumour necrosis factors, are highly conserved proteins described in all metazoan phyla. They function as inducers of extrinsic apoptotic signalling and facilitate inflammation, differentiation and cell survival. TNF-Rs use distinct adaptor molecules to activate signalling cascades. Fas-associated protein with death domain (FADD) family adaptors often mediate apoptosis, and TNF-R-associated factor (TRAF) family adaptors mediate cell differentiation and inflammation. Most of these pathway components are conserved in cnidarians, and, here, we investigated the Hydra TNF-R. We report that it is related to the ectodysplasin receptor, which is involved in epithelial cell differentiation in mammals. In Hydra, it is localised in epithelial cells with incorporated nematocytes in tentacles and body column, indicating a similar function. Further experiments suggest that it interacts with the Hydra homologue of a TRAF adaptor, but not with FADD proteins. Hydra FADD proteins colocalised with Hydra caspases in death effector filaments and recruited caspases, suggesting that they are part of an apoptotic signalling pathway. Regulating epithelial cell differentiation via TRAF adaptors therefore seems to be an ancient function of TNF-Rs, whereas FADD-caspase interactions may be part of a separate apoptotic pathway. AU - Steichele, M.* AU - Sauermann, L.S.* AU - Koenig, A. AU - Hauck, S.M. AU - Boettger, A.* C1 - 62136 C2 - 50660 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Ancestral role of TNF-R pathway in cell differentiation in the basal metazoan Hydra. JO - J. Cell Sci. VL - 134 IS - 2 PB - Company Biologists Ltd PY - 2021 SN - 0021-9533 ER - TY - JOUR AB - The GGGGCC (G(4)C(2)) repeat expansion mutation in the C9ORF72 gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Transcription of the repeat and formation of nuclear RNA foci, which sequester specific RNA-binding proteins, is one of the possible pathological mechanisms. Here, we show that (G(4)C(2))(n) repeat RNA predominantly associates with essential paraspeckle proteins SFPQ, NONO, RBM14, FUS and hnRNPH and colocalizes with known paraspeckle-associated RNA hLinc-p21. As formation of paraspeckles in motor neurons has been associated with early phases of ALS, we investigated the extent of similarity between paraspeckles and (G(4)C(2))(n) RNA foci. Overexpression of (G(4)C(2))(72) RNA results in their increased number and colocalization with SFPQ-stained nuclear bodies. These paraspeckle-like (G(4)C(2))(72) RNA foci form independently of the known paraspeckle scaffold, the long non-coding RNA NEAT1. Moreover, the knockdown of SFPQ protein in C9ORF72 expansion mutation-positive fibroblasts significantly reduces the number of (G(4)C(2))(n) RNA foci. In conclusion, (G(4)C(2))(n) RNA foci have characteristics of paraspeckles, which suggests that both RNA foci and paraspeckles play roles in FTD and ALS, and implies approaches for regulation of their formation. AU - Česnik, A.B.* AU - Darovic, S.* AU - Mihevc, S.P.* AU - Štalekar, M.* AU - Malnar, M.* AU - Motaln, H.* AU - Lee, Y.B.* AU - Mazej, J.* AU - Pohleven, J.* AU - Grosch, M. AU - Modic, M. AU - Fonovič, M.* AU - Turk, B.* AU - Drukker, M. AU - Shaw, C.E.* AU - Rogelj, B.* C1 - 55489 C2 - 46310 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Nuclear RNA foci from C9ORF72 expansion mutation form paraspeckle-like bodies. JO - J. Cell Sci. VL - 132 IS - 5 PB - Company Biologists Ltd PY - 2019 SN - 0021-9533 ER - TY - JOUR AB - VGLL proteins are transcriptional co-factors that bind TEAD family transcription factors to regulate events ranging from wing development in fly, to muscle fibre composition and immune function in mice. Here, we characterise Vgll3 in skeletal muscle. We found that mouse Vgll3 was expressed at low levels in healthy muscle but that its levels increased during hypertrophy or regeneration; in humans, VGLL3 was highly expressed in tissues from patients with various muscle diseases, such as in dystrophic muscle and alveolar rhabdomyosarcoma. Interaction proteomics revealed that VGLL3 bound TEAD1, TEAD3 and TEAD4 in myoblasts and/or myotubes. However, there was no interaction with proteins from major regulatory systems such as the Hippo kinase cascade, unlike what is found for the TEAD co-factors YAP (encoded by YAP1) and TAZ (encoded by WWTR1). Vgll3 overexpression reduced the activity of the Hippo negative-feedback loop, affecting expression of muscle-regulating genes including Myf5, Pitx2 and Pitx3, and genes encoding certain Wnts and IGFBPs. VGLL3 mainly repressed gene expression, regulating similar genes to those regulated by YAP and TAZ. siRNA-mediated Vgll3 knockdown suppressed myoblast proliferation, whereas Vgll3 overexpression strongly promoted myogenic differentiation. However, skeletal muscle was overtly normal in Vgll3-null mice, presumably due to feedback signalling and/or redundancy. This work identifies VGLL3 as a transcriptional co-factor operating with the Hippo signal transduction network to control myogenesis. AU - Figeac, N.* AU - Mohamed, A.D. AU - Sun, C.* AU - Schönfelder, M.* AU - Matallanas, D.* AU - Garcia-Munoz, A.* AU - Missiaglia, E.* AU - Collie-Duguid, E.* AU - De Mello, V.* AU - Pobbati, A.V.* AU - Pruller, J.* AU - Jaka, O.* AU - Harridge, S.D.R.* AU - Hong, W.* AU - Shipley, J.* AU - Vargesson, N.* AU - Zammit, P.S.* AU - Wackerhage, H.* C1 - 56185 C2 - 46875 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - VGLL3 operates via TEAD1, TEAD3 and TEAD4 to influence myogenesis in skeletal muscle. JO - J. Cell Sci. VL - 132 IS - 13 PB - Company Biologists Ltd PY - 2019 SN - 0021-9533 ER - TY - JOUR AB - The Fe(II) and 2-oxoglutarate-dependent oxygenase Alkb homologue 1 (Alkbh1) has been shown to act on a wide range of substrates, like DNA, tRNA and histones. Thereby different enzymatic activities have been identified including, among others, demethylation of N3-methylcytosine (m(3)C) in RNA- and single-stranded DNA oligonucleotides, demethylation of N-1-methyladenosine (m1A) in tRNA or formation of 5-formyl cytosine (f(5)C) in tRNA. In accordance with the different substrates, Alkbh1 has also been proposed to reside in distinct cellular compartments in human and mouse cells, including the nucleus, cytoplasm and mitochondria. Here, we describe further evidence for a role of human Alkbh1 in regulation of mitochondrial protein biogenesis, including visualizing localization of Alkbh1 into mitochondrial RNA granules with super-resolution 3D SIM-microscopy. Electron microscopy and high-resolution respirometry analyses revealed an impact of Alkbh1 level on mitochondrial respiration, but not on mitochondrial structure. Downregulation of Alkbh1 impacts cell growth in HeLa cells and delays development in Caenorhabditis elegans, where the mitochondrial role of Alkbh1 seems to be conserved. Alkbh1 knockdown, but not Alkbh7 knockdown, triggers the mitochondrial unfolded protein response (UPRmt) in C. elegans. AU - Wagner, A. AU - Hofmeister, O. AU - Rolland, S.G.* AU - Maiser, A.* AU - Aasumets, K.* AU - Schmitt, S.* AU - Schorpp, K.K. AU - Feuchtinger, A. AU - Hadian, K. AU - Schneider, S.* AU - Zischka, H. AU - Leonhardt, H.* AU - Conradt, B.* AU - Gerhold, J.M.* AU - Wolf, A. C1 - 56799 C2 - 47351 CY - Bidder Building, Station Rd, Histon, Cambridge Cb24 9lf, England TI - Mitochondrial Alkbh1 localizes to mtRNA granules and its knockdown induces the mitochondrial UPR in humans and C. elegans. JO - J. Cell Sci. VL - 132 IS - 19 PB - Company Biologists Ltd PY - 2019 SN - 0021-9533 ER - TY - JOUR AB - Activation and invasion of the vascular endothelium by Staphylococcus aureus (S. aureus) is a major cause of sepsis and endocarditis. For endothelial cell invasion, S. aureus triggers actin polymerization via Cdc42, N-WASp and Arp2/3 complex to assemble a phagocytic cup-like structure. Here we show that after stimulating actin polymerization staphylococci recruit Cdc42GAP which deactivates Cdc42 and terminates actin polymerization in the phagocytic cups. Cdc42GAP is delivered to the invading bacteria on recycling endocytic vesicles in concert with exocyst complex. When Cdc42GAP recruitment by staphylococci was prevented by blocking recycling endocytic vesicles or exocyst complex or when Cdc42 was constitutively activated, phagocytic cup closure was impaired and endothelial cell invasion was inhibited. Thus, to complete invasion of the endothelium staphylococci reorient recycling endocytic vesicles to recruit Cdc42GAP which terminates Cdc42-induced actin polymerization in phagocytic cups. Analogical mechanisms may govern other Cdc42-dependent cell functions. AU - Rauch, L.* AU - Hennings, K.* AU - Trasak, C.* AU - Röder, A.* AU - Schröder, B. AU - Koch-Nolte, F.* AU - Rivera-Molina, F.* AU - Toomre, D.* AU - Aepfelbacher, M.* C1 - 48836 C2 - 41439 CY - Cambridge SP - 2937-2949 TI - Staphylococcus aureus recruits Cdc42GAP via recycling endosomes and exocyst to invade human endothelial cells. JO - J. Cell Sci. VL - 129 IS - 15 PB - Company Of Biologists Ltd PY - 2016 SN - 0021-9533 ER - TY - JOUR AB - Correct innervation of the main respiratory muscle in mammals, namely the thoracic diaphragm, is a crucial pre-requisite for the functionality of this muscle and the viability of the entire organism. Systemic impairment of Sema3A-Npn-1 signaling causes excessive branching of phrenic nerves in the diaphragm and into the central tendon region, where the majority of misguided axons innervate ectopic musculature. To elucidate whether these ectopic muscles are a result of misguided myoblast precursors due to the loss of Sema3A-Npn-1 signaling, we conditionally ablated Npn-1 in somatic motor neurons which leads to a similar phenotype of phrenic nerve defasciculation and, intriguingly, also formation of innervated ectopic muscles. We therefore hypothesize that ectopic myocyte fusion is caused by additional factors released by misprojecting growth cones. Slit2 and its Robo receptors are expressed by phrenic motor axons and migrating myoblasts, respectively, during innervation of the diaphragm. In vitro analyses revealed a chemo-attractive effect of Slit2 on primary diaphragm myoblasts. Thus, we postulate an influence of factors released by motor neuron growth cones on the migration properties of myoblasts during establishment of the diaphragm. AU - Saller, M. AU - Hüttl, R.E. AU - Hanuschick, P. AU - Amend, A.-L. AU - Alberton, P.* AU - Aszodi, A.* AU - Huber, A.B. C1 - 49184 C2 - 41705 CY - Cambridge SP - 3295-3308 TI - The role of Sema3-Npn-1 signaling during diaphragm innervation and muscle development. JO - J. Cell Sci. VL - 129 IS - 17 PB - Company Of Biologists Ltd PY - 2016 SN - 0021-9533 ER - TY - JOUR AB - Knowledge about the molecular structure of PKA isoforms is substantial. In contrast, the dynamics of PKA isoform activity in living primary cells has not been investigated in detail. Using a High Content Screening microscopy approach, we identified the RIIβ subunit of PKA-II to be predominantly expressed in a subgroup of sensory neurons. The RIIβ-positive subgroup included most neurons expressing nociceptive markers (TRPV1, NaV1.8, CGRP, IB4) and responded to pain eliciting capsaicin with calcium influx. Isoform-specific PKA reporters showed in sensory neuron-derived F11 cells that the inflammatory mediator PGE2 specifically activated PKA-II but not PKA-I. Accordingly, pain sensitizing inflammatory mediators and activators of PKA increased the phosphorylation of RII subunits (pRII) in subgroups of primary sensory neurons. Detailed analyses revealed basal pRII to be regulated by the phosphatase PP2A. Increase of pRII was followed by phosphorylation of CREB in a PKA-dependent manner. Thus, we propose RII phosphorylation to represent an isoform-specific readout for endogenous PKA-II activity in vivo, suggest RIIβ as a novel nociceptive subgroup marker, and extend the current model of PKA-II activation by introducing a PP2A-dependent basal state. AU - Isensee, J.* AU - Diskar, M.* AU - Waldherr, S.* AU - Buschow, R.* AU - Hasenauer, J. AU - Prinz, A.* AU - Allgöwer, F.* AU - Herberg, F.W.* AU - Hucho, T.* C1 - 28186 C2 - 32999 SP - 216-229 TI - Pain modulators regulate the dynamics of PKA-RII phosphorylation in subgroups of sensory neurons. JO - J. Cell Sci. VL - 127 IS - 1 PB - Company of Biologists PY - 2014 SN - 0021-9533 ER - TY - JOUR AB - The GTPase Ras can either promote or inhibit cell survival. Inactivating mutations in RasGAP (vap), a Ras GTPase-activating protein, lead to age-related brain degeneration in Drosophila. Genetic interactions implicate the epidermal growth factor receptor (EGFR)-Ras pathway in promoting neurodegeneration but the mechanism is not known. Here we show that the Src homology 2 (SH2) domains of RasGAP are essential for its neuroprotective function. By using affinity purification and mass spectrometry, we identify a complex containing RasGAP together with Sprint, a Ras effector and putative activator of the endocytic GTPase Rab5. Formation of the RasGAP-Sprint complex requires the SH2 domains of RasGAP and tyrosine phosphorylation of Sprint. RasGAP and Sprint co-localize with Rab5-positive early endosomes but not with Rab7-positive late endosomes. We demonstrate a key role for this interaction in neurodegeneration: mutation of Sprint (or Rab5) suppresses neuronal cell death caused by the loss of RasGAP. These results indicate that the long-term survival of adult neurons in Drosophila is critically dependent on the activities of two GTPases, Ras and Rab5, regulated by the interplay of RasGAP and Sprint. AU - Rowshanravan, B.* AU - Woodcock, S.A.* AU - Botella, J.A.* AU - Kiermayer, C. AU - Schneuwly, S.* AU - Hughes, D.A.* C1 - 31537 C2 - 34536 CY - Cambridge SP - 2849-2861 TI - RasGAP mediates neuronal survival in Drosophila through direct regulation of Rab5-dependent endocytosis. JO - J. Cell Sci. VL - 127 IS - 13 PB - Company Of Biologists Ltd PY - 2014 SN - 0021-9533 ER - TY - JOUR AB - Class-3 semaphorins are anti-angiogenic and anti-tumorigenic guidance factors that bind to neuropilins which in turn associate with class-A plexins to transduce semaphorin signals. To study the role of the plexin-A2 receptor in semaphorin signaling, we silenced its expression in endothelial cells and in glioblastoma cells. The silencing did not affect sema3A signaling which depended on neuropilin-1, plexin-A1 and plexin-A4, but abolished completely sema3B signaling which required in addition plexin-A4 and one of the two neuropilins. Interestingly, over-expression of plexin-A2 in plexin-A1 or plexin-A4 silenced cells restored responses to both semaphorins although it nullified their ability to differentiate between them, suggesting that when over-expressed plexin-A2 is functionally interchangeable with other class-A plexins. In-contrast, although plexin-A4 over-expression restored sema3A signaling in plexin-A1 silenced cells, it failed to restore sema3B signaling in plexin-A2 silenced cells. It follows that the identity of plexins in functional semaphorin receptors can be flexible depending on their expression level. Our results suggest that changes in the expression of plexins induced by microenvironmental cues can trigger differential responses of different populations of migrating cells to encountered gradients of semaphorins. AU - Sabag, A.D.* AU - Smolkin, T.* AU - Mumblat, Y.* AU - Ueffing, M. AU - Kessler, O.* AU - Gloeckner, C.J. AU - Neufeld, G.* C1 - 32632 C2 - 35179 SP - 5240-5252 TI - The role of the plexin-A2 receptor in semaphorin-3A and semaphorin-3B signal transduction. JO - J. Cell Sci. VL - 127 IS - 24 PY - 2014 SN - 0021-9533 ER - TY - JOUR AB - Carefully orchestrated intercellular communication is an essential prerequisite for the development of multicellular organisms. In recent years, tunneling nanotubes (TNT) have emerged as a novel and widespread mechanism of cell-cell communication. However, the molecular basis of their formation is still poorly understood. In the present study we report that the transmembrane MHC class III protein LST1 induces the formation of functional nanotubes and is required for endogenous nanotube generation. Mechanistically, we found LST1 to induce nanotube formation by recruiting the small GTPase RalA to the plasma membrane and promoting its interaction with the exocyst complex. Furthermore, we determined LST1 to recruit the actin-crosslinking protein filamin to the plasma membrane and to interact with M-Sec, myosin and myoferlin. These results allow us to suggest a molecular model for nanotube generation. In this proposal LST1 functions as a membrane scaffold mediating the assembly of a multimolecular complex, which controls the formation of functional nanotubes. AU - Schiller, C. AU - Diakopoulos, K.N.* AU - Rohwedder, I.* AU - Kremmer, E. AU - von Toerne, C. AU - Ueffing, M. AU - Weidle, U.H.* AU - Ohno, H.* AU - Weiss, E.H.* C1 - 11592 C2 - 30705 SP - 767-777 TI - LST1 promotes the assembly of a molecular machinery responsible for tunneling nanotube formation. JO - J. Cell Sci. VL - 126 IS - 3 PB - Company of Biologists Ltd. PY - 2013 SN - 0021-9533 ER - TY - JOUR AB - MIM/MTSS1 is a tissue-specific regulator of plasma membrane dynamics, whose altered expression levels have been linked to cancer metastasis. MIM deforms phosphoinositide-rich membranes through its I-BAR domain and interacts with actin monomers through its WH2 domain. Recent work proposed that MIM also potentiates Sonic hedgehog (Shh)-induced gene expression. Here, we generated MIM mutant mice and found that full-length MIM protein is dispensable for embryonic development. However, MIM-deficient mice displayed a severe urinary concentration defect caused by compromised integrity of kidney epithelia intercellular junctions, which led to bone abnormalities and end-stage renal failure. In cultured kidney epithelial (MDCK) cells, MIM displayed dynamic localization to adherens junctions, where it promoted Arp2/3-mediated actin filament assembly. This activity was dependent on the ability of MIM to interact with both membranes and actin monomers. Furthermore, results from the mouse model and cell culture experiments suggest that full-length MIM is not crucial for Shh signaling, at least during embryogenesis. Collectively, these data demonstrate that MIM modulates interplay between the actin cytoskeleton and plasma membrane to promote the maintenance of intercellular contacts in kidney epithelia. AU - Saarikangas, J.* AU - Mattila, PK.* AU - Varjosalo, M.* AU - Bovellan, M.* AU - Hakanen, J.* AU - Calzada-Wack, J. AU - Tost, M. AU - Jennen, L. AU - Rathkolb, B. AU - Hans, W.* AU - Horsch, M.* AU - Hyvönen, M.E.* AU - Perälä, N.* AU - Fuchs, H. AU - Gailus-Durner, V. AU - Esposito, I. AU - Wolf, E.* AU - Hrabě de Angelis, M. AU - Frilander, MJ.* AU - Savilahti, H.* AU - Sariola, H.* AU - Sainio, K.* AU - Lehtonen, S.* AU - Taipale, J.* AU - Salminen, M.* AU - Lappalainen, P. C1 - 5647 C2 - 28425 SP - 1245-1255 TI - Missing-in-metastasis MIM/MTSS1 promotes actin assembly at intercellular junctions and is required for integrity of kidney epithelia. JO - J. Cell Sci. VL - 124 IS - 8 PB - Company of Biologists Ltd. PY - 2011 SN - 0021-9533 ER - TY - JOUR AB - The epithelial to mesenchymal transition (EMT) is a crucial step in tumor progression, and the TGFβ-SMAD signaling pathway is an inductor of EMT in many tumor types. One hallmark of EMT is downregulation of the adherens junction protein E-cadherin, a process mediated by transcription factors such as the zinc fingers SNAIL and SLUG. Here, we report that the catalytic IκB kinase (IKK) subunit IKKα is necessary for the silencing of E-cadherin in a Panc1 cell model of TGFβ-SMAD-mediated EMT, independently of NFκB. IKKα regulates canonical TGFβ-SMAD signaling by interacting with SMAD3 and controlling SMAD complex formation on DNA. Furthermore, we demonstrate that the TGFβ-IKKα-SMAD signaling pathway induces transcription of the genes encoding SNAIL and SLUG. In addition, we demonstrate that IKKα also modulates canonical TGFβ-SMAD signaling in human MDA-MB231 breast cancer cells, arguing for a more general impact of IKKα on the control of TGFβ-SMAD signaling. Taken together, these findings indicate that IKKα contributes to the tumor-promoting function of the TGFβ-SMAD signaling pathway in particular cancers. AU - Brandl, M.* AU - Seidler, B.* AU - Haller, F. AU - Adamski, J. AU - Schmid, R.M.* AU - Saur, D.* AU - Schneider, G.* C1 - 1345 C2 - 28022 SP - 4231-4239 TI - IKKα controls canonical TGFß-SMAD signaling to regulate genes expressing SNAIL and SLUG during EMT in panc1 cells. JO - J. Cell Sci. VL - 123 IS - 24 PB - Company of Biologists PY - 2010 SN - 0021-9533 ER - TY - JOUR AB - Epithelial junctions are dynamically and functionally linked to the actin cytoskeleton, and their disassembly is a key event during physiological and pathological processes. We recently showed that epithelial disintegration facilitates transcriptional activation via Rac, G-actin, MAL (also known as MRTF) and serum response factor (SRF). Here, we investigate which specific component of the epithelial junction is essential for this MAL-SRF-mediated transcription. The Ca(2+)-dependent dissociation of polarised epithelial cells depleted of ZO proteins - which form adherens junctions (AJs) but completely lack tight junctions (TJs) - fully activated SRF. By contrast, AGS gastric adenocarcinoma epithelial cells, which form TJs but are deficient in E-cadherin, and therefore also in AJs, failed to activate SRF. The introduction of wild-type E-cadherin in AGS cells restored AJ formation and MAL-SRF inducibility. To gain further insight into the membrane-proximal signalling, AGS cells were stably transfected with E-cadherin-alpha-catenin fusions. Despite restored formation of cell-cell contacts containing the nectin-afadin complex and p120-catenin, these cells did not activate SRF upon junction dissociation, suggesting that signal transmission depends on the C-terminal tail of E-cadherin. We conclude that the dissociation of intercellular E-cadherin interactions from AJs, and signals originating from the C-terminal region covering the beta-catenin-binding site of E-cadherin, are essential for transcriptional activation via Rac, MAL and SRF, whereas TJs are not involved. AU - Busche, S.* AU - Kremmer, E. AU - Posern, G.* C1 - 5305 C2 - 27526 SP - 2803-2809 TI - E-cadherin regulates MAL-SRF-mediated transcription in epithelial cells. JO - J. Cell Sci. VL - 123 IS - 16 PB - Company of Biologists Ltd. PY - 2010 SN - 0021-9533 ER - TY - JOUR AB - The microenvironment of growth factors in the subependymal zone (SEZ) of the adult brain provides the instructive milieu for neurogenesis to proceed in this germinal niche. In particular, tight regulation of bone morphogenetic protein (BMP) signaling is essential to balance proliferative and non-proliferative cell fate specification. However, the regulatory pathways that control BMP signaling in the SEZ are still poorly defined. We demonstrate that LRP2, a clearance receptor for BMP4 is specifically expressed in ependymal cells of the lateral ventricles in the adult brain. Intriguingly, expression is restricted to the ependyma that faces the stem cell niche. Expression is not seen in ependyma elsewhere in the lateral ventricles or in the dentate gyrus, the second major neurogenic zone of the adult brain. We further show that lack of LRP2 expression in adult mice results in impaired proliferation of neural precursor cells in the SEZ resulting in decreased numbers of neuroblasts reaching the olfactory bulb. Reduced neurogenesis coincides with increased BMP4 expression and enhanced activation of downstream mediators phospho-SMAD1/5/8 and ID3 in the stem cell niche. Our findings suggest a novel mechanism whereby LRP2-mediated catabolism of BMP4 in the ependyma modulates the microenvironment of the SEZ and enables adult neurogenesis to proceed. AU - Gajera, C.R.* AU - Emich, H.* AU - Lioubinski, O.* AU - Christ, A.* AU - Beckervordersandforth-Bonk, R. AU - Yoshikawa, K.* AU - Bachmann, S.* AU - Christensen, E.I.* AU - Götz, M. AU - Kempermann, G.* AU - Peterson, A.S.* AU - Willnow, T.E.* AU - Hammes, A.* C1 - 1303 C2 - 27361 SP - 1922-1930 TI - LRP2 in ependymal cells regulates BMP signaling in the adult neurogenic niche. JO - J. Cell Sci. VL - 123 IS - 11 PB - Company of Biologists Ltd. PY - 2010 SN - 0021-9533 ER - TY - JOUR AB - In this study, we characterize the molecular and functional features of a novel protein called SPOC1. SPOC1 RNA expression was previously reported to be highest in highly proliferating tissues and increased in a subset of ovarian carcinoma patients, which statistically correlated with poor prognosis and residual disease. These observations implied that SPOC1 might play a role in cellular proliferation and oncogenesis. Here we show that the endogenous SPOC1 protein is labile, primarily chromatin associated and its expression as well as localization are regulated throughout the cell cycle. SPOC1 is dynamically regulated during mitosis with increased expression levels and biphasic localization to mitotic chromosomes indicating a functional role of SPOC1 in mitotic processes. Consistent with this postulate, SPOC1 siRNA knockdown experiments resulted in defects in mitotic chromosome condensation, alignment and aberrant sister chromatid segregation. Finally, we have been able to show, using micrococcal nuclease (MNase) chromatin-digestion assays that SPOC1 expression levels proportionally influence the degree of chromatin compaction. Collectively, our findings show that SPOC1 modulates chromatin structure and that tight regulation of its expression levels and subcellular localization during mitosis are crucial for proper chromosome condensation and cell division. AU - Kinkley, S.* AU - Staege, H.* AU - Mohrmann, G.* AU - Rohaly, G.* AU - Schaub, T.* AU - Kremmer, E. AU - Winterpacht, A.* AU - Will, H.* C1 - 2014 C2 - 26512 SP - 2946-2956 TI - SPOC1: A novel PHD-containing protein modulating chromatin structure and mitotic chromosome condensation. JO - J. Cell Sci. VL - 122 IS - 16 PB - Company Of Biologists Ltd PY - 2009 SN - 0021-9533 ER - TY - JOUR AB - Actin disruption by CytochalasinD (CytD) and LatrunculinB (LatB) induced NF-kappaB activation in myelomonocytic and intestinal epithelial cells. In an attempt to elucidate the mechanism by which actin disruption induced IKK activation, we studied the human Nod2 protein, which was able to induce NF-kappaB activation and whose expression was restricted to myelomonocytic and intestinal epithelial cells. Nod2 is thought to play key roles in pathogen defence through sensing bacteria and generating an inflammatory immune response. We showed that actin disruption by CytD significantly and specifically increased Nod2-mediated NF-kappaB signaling. Nod2 was fully partitioned in the Triton-X-100-insoluble fraction but translocated into the soluble fraction after CytD treatment, demonstrating that the presence of Nod2 in the detergent-insoluble pellet was specific to actin cytoskeleton. Confocal analysis also revealed a Nod2 colocalization with membrane-associated F-actin. Colocalization and co-immunoprecipitation assays with endogenous Rac1 have shown that Nod2 associated with activated Rac1 in membrane ruffles through both its N-terminal caspase recruitment domains (CARD) and C-terminal leucine-rich repeats (LRRs). Membrane ruffle disruption by a Rac1 dominant negative form primed Nod2-dependent NF-kappaB signaling. The recruitment of Nod2 in Rac-induced dynamic cytoskeletal structures could be a strategy to both repress the Nod2-dependent NF-kappaB signaling in unstimulated cells and rapidly mobilize Nod2 during bacterial infection. AU - Legrand-Poels, S.* AU - Kustermans, G.* AU - Bex, F.* AU - Kremmer, E. AU - Kufer, T.A.* AU - Piette, J.* C1 - 1877 C2 - 24807 SP - 1299-1310 TI - Modulation of Nod2-dependent NF-kB signaling by the actin cytoskeleton. JO - J. Cell Sci. VL - 120 IS - 7 PB - Company of Biologists Limited PY - 2007 SN - 0021-9533 ER - TY - JOUR AU - Lehmann, M.H. AU - Masanetz, S. AU - Kramer, S. AU - Erfle, V. C1 - 5115 C2 - 24158 SP - 4520-4530 TI - HIV-1 Nef upregulates CCL2/MCP-1 expression in astrocytes in a myristoylation- and calmodulin-dependent manner. JO - J. Cell Sci. VL - 119 PY - 2006 SN - 0021-9533 ER - TY - JOUR AU - Ritzi, M. AU - Tillack, K. AU - Gerhardt, J. AU - Ott, E. AU - Humme, S. AU - Kremmer, E. AU - Hammerschmidt, W. AU - Schepers, A. C1 - 10104 C2 - 21197 SP - 3971-3984 TI - Complex protein-DNA dynamics at the latent origin of DNA replication of Epstein-Barr virus. JO - J. Cell Sci. VL - 116 PY - 2003 SN - 0021-9533 ER - TY - JOUR AU - Raderschall, E.* AU - Bazarov, A.* AU - Cao, J.* AU - Lurz, R.* AU - Smith, A.* AU - Mann, W.* AU - Ropers, H.-H.* AU - Sedivy, J.M.* AU - Golub, E.I.* AU - Fritz, E. AU - Haaf, Th.* C1 - 21986 C2 - 20514 SP - 153-164 TI - Formation of higher-order nuclear Rad51 structures is functionally linked to p21 expression and protection from DNA damage-induced apoptosis. JO - J. Cell Sci. VL - 115 PY - 2002 SN - 0021-9533 ER - TY - JOUR AB - Astrocytes are cellular targets for the human immunodeficiency virus (HIV) that limit virus production, owing, at least in part, to the diminished functionality of the viral post-transcriptional stimulatory factor Rev. To understand the trafficking process in astrocytes, we compared nucleocytoplasmic transport of Rev and various proteins with well-characterized nucleocytoplasmic transport features in human astrocytes and control cells (HeLa). Localization and trafficking characteristics of several cellular and viral proteins, as well as nuclear trafficking of classical peptide signals upon microinjection were similar in both cell types, indicating maintenance of general features of nucleocytoplasmic transport in astrocytes. Quantification of fluorescence in living cells expressing Rev fused to green fluorescent protein (GFP) indicated a strong shift in intracellular distribution of Rev in astrocytes, with 50-70% of Rev in the cytoplasm, whereas the cytoplasmic proportion of Rev in HeLa cells is around 10%. The dynamics of nucleocytoplasmic trafficking of Rev were compared in astrocytes and Rev-permissive cells by monitoring migration of Rev-GFP in cell fusions using highly sensitive time-lapse imaging. Nuclear uptake of Rev was dramatically retarded in homo-polykaryons of astrocytes compared with control cells. Diminished nuclear uptake of Rev was also observed in hetero-polykaryons of Rev-permissive cells and astrocytes. These results indicate that astrocytes contain a cytoplasmic activity that interferes with nuclear uptake of Rev. Our studies suggest a model in which Rev is prevented from functioning efficiently in astrocytes by specific alterations of its nucleocytoplasmic trafficking properties. AU - Neumann, M. AU - Afonina, E.* AU - Ceccherini-Silberstein, F. AU - Schlicht, S. AU - Erfle, V. AU - Pavlakis, G.N.* AU - Brack-Werner, R. C1 - 24078 C2 - 31398 SP - 1717-1729 TI - Nucleocytoplasmic transport in human astrocytes: Decreased nuclear uptake of the HIV Rev shuttle protein. JO - J. Cell Sci. VL - 114 IS - Pt 9 PB - Company of Biologists PY - 2001 SN - 0021-9533 ER -