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Levayer R. Staying away from the breaking point: Probing the limits of epithelial cell elimination. Curr Opin Cell Biol 2024; 86:102316. [PMID: 38199024 DOI: 10.1016/j.ceb.2023.102316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 12/11/2023] [Accepted: 12/18/2023] [Indexed: 01/12/2024]
Abstract
Epithelial tissues are dramatically remodelled during embryogenesis and tissue homeostasis and yet need to maintain their sealing properties to sustain their barrier functions at any time. Part of these remodellings involve the elimination of a large proportion of cells through apoptosis. Cell extrusion, the remodelling steps leading to seamless dying cell expulsion, helps to maintain tissue cohesion. However, there is an intrinsic limit in the system that can only accommodate a certain proportion/rate of cell elimination as well as certain spatiotemporal distributions. What are then the critical conditions leading to epithelial rupture/tear/sealing defects upon cell elimination and which mechanisms ensure that such limits are never reached? In this short review, I document the conditions in which epithelial rupture has been observed, including in the contexts of epithelial cell death, and the mechanical parameters influencing tissue rupture, and review feedback mechanisms which help to keep the epithelia away from the breaking point.
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Affiliation(s)
- Romain Levayer
- Department of Developmental and Stem Cell Biology, Institut Pasteur, Université de Paris Cité, CNRS UMR 3738, 25 rue du Dr. Roux, 75015 Paris, France.
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Cell polarity and extrusion: How to polarize extrusion and extrude misspolarized cells? Curr Top Dev Biol 2023; 154:131-167. [PMID: 37100516 DOI: 10.1016/bs.ctdb.2023.02.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The barrier function of epithelia is one of the cornerstones of the body plan organization of metazoans. It relies on the polarity of epithelial cells which organizes along the apico-basal axis the mechanical properties, signaling as well as transport. This barrier function is however constantly challenged by the fast turnover of epithelia occurring during morphogenesis or adult tissue homeostasis. Yet, the sealing property of the tissue can be maintained thanks to cell extrusion: a series of remodeling steps involving the dying cell and its neighbors leading to seamless cell expulsion. Alternatively, the tissue architecture can also be challenged by local damages or the emergence of mutant cells that may alter its organization. This includes mutants of the polarity complexes which can generate neoplastic overgrowths or be eliminated by cell competition when surrounded by wild type cells. In this review, we will provide an overview of the regulation of cell extrusion in various tissues focusing on the relationship between cell polarity, cell organization and the direction of cell expulsion. We will then describe how local perturbations of polarity can also trigger cell elimination either by apoptosis or by cell exclusion, focusing specifically on how polarity defects can be directly causal to cell elimination. Overall, we propose a general framework connecting the influence of polarity on cell extrusion and its contribution to aberrant cell elimination.
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Hoshika S, Sun X, Kuranaga E, Umetsu D. Reduction of endocytic activity accelerates cell elimination during tissue remodeling of the Drosophila epidermal epithelium. Development 2020; 147:dev.179648. [PMID: 32156754 DOI: 10.1242/dev.179648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 02/24/2020] [Indexed: 12/22/2022]
Abstract
Epithelial tissues undergo cell turnover both during development and for homeostatic maintenance. Cells that are no longer needed are quickly removed without compromising the barrier function of the tissue. During metamorphosis, insects undergo developmentally programmed tissue remodeling. However, the mechanisms that regulate this rapid tissue remodeling are not precisely understood. Here, we show that the temporal dynamics of endocytosis modulate physiological cell properties to prime larval epidermal cells for cell elimination. Endocytic activity gradually reduces as tissue remodeling progresses. This reduced endocytic activity accelerates cell elimination through the regulation of Myosin II subcellular reorganization, junctional E-cadherin levels, and caspase activation. Whereas the increased Myosin II dynamics accelerates cell elimination, E-cadherin plays a protective role against cell elimination. Reduced E-cadherin is involved in the amplification of caspase activation by forming a positive-feedback loop with caspase. These findings reveal the role of endocytosis in preventing cell elimination and in the cell-property switching initiated by the temporal dynamics of endocytic activity to achieve rapid cell elimination during tissue remodeling.
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Affiliation(s)
- Shinichiro Hoshika
- Laboratory for Histogenetic Dynamics, Department of Ecological Developmental Adaptability Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Xiaofei Sun
- Laboratory for Histogenetic Dynamics, Department of Ecological Developmental Adaptability Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Erina Kuranaga
- Laboratory for Histogenetic Dynamics, Department of Ecological Developmental Adaptability Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Daiki Umetsu
- Laboratory for Histogenetic Dynamics, Department of Ecological Developmental Adaptability Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai, 980-8578, Japan
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Liu J, Giri BR, Chen Y, Luo R, Xia T, Grevelding CG, Cheng G. Schistosoma japonicum IAP and Teg20 safeguard tegumental integrity by inhibiting cellular apoptosis. PLoS Negl Trop Dis 2018; 12:e0006654. [PMID: 30044778 PMCID: PMC6078320 DOI: 10.1371/journal.pntd.0006654] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 08/06/2018] [Accepted: 06/29/2018] [Indexed: 11/18/2022] Open
Abstract
Schistosomes are causative agents of human schistosomiasis, which is endemic in tropical and subtropical areas of the world. Adult schistosomes can survive in their final hosts for several decades, and they have evolved various strategies to overcome the host immune response. Consequently, understanding the mechanisms that regulate parasitic cell survival will open avenues for developing novel strategies against schistosomiasis. Our previous study suggested that an inhibitor of apoptosis protein in Schistosoma japonicum (SjIAP) may play important roles in parasitic survival and development. Here, we demonstrated that SjIAP can negatively regulate cellular apoptosis in S. japonicum by suppressing caspase activity. Immunohistochemistry analysis indicated that SjIAP ubiquitously expressed within the worm body including the tegument. Silencing of SjIAP expression via small interfering RNA led to destruction of the tegument integrity in schistosomes. We further used co-immunoprecipitation to identify interaction partners of SjIAP and revealed the tegument protein SjTeg-20 as a putative interacting partner of SjIAP. The interaction between SjIAP and SjTeg-20 was confirmed by a yeast two-hybrid (Y2H) assay. Moreover, results of a TUNEL assay, RNA interference, scanning and transmission electron microscopy, caspase assays, transcript profiling, and protein localization of both interacting molecules provided first evidence for an essential role of SjIAP and SjTeg-20 to maintain the structural integrity of the tegument by negatively regulating apoptosis. Taken together, our findings suggest that the cooperative activities of SjIAP and SjTeg-20 belong to the strategic inventory of S. japonicum ensuring survival in the hostile environment within the vasculature of the final host. Schistosomiasis is a worldwide public health concern particularly in developing countries. The causative agents, schistosomes, can survive within the vascular system of their final hosts for several decades despite facing the host’s immune response. Therefore, elucidating the mechanism of cell survival will contribute to the understanding of host-parasite interaction and may lead to the identification of suitable targets for developing novel strategies against schistosomiasis. Inhibitor of apoptosis proteins are highly conserved proteins functioning as endogenous inhibitors of apoptotic cell death. Here, we demonstrated that an inhibitor of apoptosis protein of Schistosoma japonicum (SjIAP) governs the integrity of the tegument of schistosomes by inhibiting cellular apoptosis of the parasite. Further studies revealed that SjTeg-20, an S. japonicum tegumental protein, cooperates with SjIAP to inhibit apoptosis in schistosomes. Our findings provide new insights into the role of SjIAP and SjTeg-20 in maintaining the integrity of the worm tegument by negatively regulating apoptosis.
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Affiliation(s)
- Juntao Liu
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
| | - Bikash R. Giri
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
| | - Yongjun Chen
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
| | - Rong Luo
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
| | - Tianqi Xia
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
| | | | - Guofeng Cheng
- Department of Animal Schistosomiasis, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture, Shanghai, China
- * E-mail: ,
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Torres AY, Malartre M, Pret AM, Agnès F. JAK/STAT signaling is necessary for cell monosis prior to epithelial cell apoptotic extrusion. Cell Death Dis 2017; 8:e2814. [PMID: 28542149 PMCID: PMC5520696 DOI: 10.1038/cddis.2017.166] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/12/2017] [Accepted: 03/13/2017] [Indexed: 12/19/2022]
Abstract
Epithelial cell extrusion is crucial for proper development and tissue homeostasis. High-resolution 3D reconstruction and 4D imaging, combined with genetic analyis, have allowed us to reveal the highly-sterotyped morphogenetic events controlled by JAK/STAT signaling in a developmentally-programmed case of epithelial cell extrusion. Specialized somatic cells, Polar Cells (PCs), are produced in excess and then undergo apoptotic elimination from the follicular epithelium in the Drosophila ovary. We show that supernumerary PCs are first systematically enveloped by PC neighbors on all sides, first laterally, then apically in conjunction with highly-reinforced adherens junctions, and finally basally. The PC to be removed thus loses all contact with follicle cells, germline cells and the basement membrane in a process we have called cell 'monosis', for 'isolation' in Greek. PC monosis takes several hours, and always precedes, and is independent of, activation of apoptosis. JAK/STAT signaling is necessary within the surrounding follicular epithelium for PC monosis. Minutes after monosis is complete, PC apoptotic corpses are formed and extruded laterally within the epithelium, in contrast to the apical and basal extrusions described to date. These apoptotic corpses are engulfed and eliminated by surrounding follicle cells, which are thus acting as non-professional phagocytes. This study therefore shows the non cell-autonomous impact of an epithelium, via JAK/STAT signaling activation, on cell morphogenesis events leading to apoptotic extrusion. It is likely that the use of high-resolution 3D and 4D imaging, which allows for better spatio-temporal understanding of morphogenetic events, will reveal that cell monosis and lateral extrusion within an epithelium are pertinent for other cases of epithelial cell extrusion as well.
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Affiliation(s)
- Alba Y Torres
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France
| | - Marianne Malartre
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France
| | - Anne-Marie Pret
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, Université, Paris-Saclay, 91198 Gif-sur-Yvette Cedex France
- Université de Versailles St Quentin en Yvelines, 78035 Versailles, France
| | - François Agnès
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette Cedex, France
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Berthelet J, Dubrez L. Regulation of Apoptosis by Inhibitors of Apoptosis (IAPs). Cells 2013; 2:163-87. [PMID: 24709650 PMCID: PMC3972657 DOI: 10.3390/cells2010163] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 01/05/2023] Open
Abstract
Abstract Inhibitors of Apoptosis (IAPs) are a family of proteins with various biological functions including regulation of innate immunity and inflammation, cell proliferation, cell migration and apoptosis. They are characterized by the presence of at least one N-terminal baculoviral IAP repeat (BIR) domain involved in protein-protein interaction. Most of them also contain a C-terminal RING domain conferring an E3-ubiquitin ligase activity. In drosophila, IAPs are essential to ensure cell survival, preventing the uncontrolled activation of the apoptotic protease caspases. In mammals, IAPs can also regulate apoptosis through controlling caspase activity and caspase-activating platform formation. Mammalian IAPs, mainly X-linked IAP (XIAP) and cellular IAPs (cIAPs) appeared to be important determinants of the response of cells to endogenous or exogenous cellular injuries, able to convert the survival signal into a cell death-inducing signal. This review highlights the role of IAP in regulating apoptosis in Drosophila and Mammals.
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Affiliation(s)
- Jean Berthelet
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
| | - Laurence Dubrez
- Institut National de la Santé et de la Recherche Médicale (Inserm), UMR866, Dijon F-21079, France.
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Abstract
During morphogenesis, tissues are shaped by cell behaviors such as apical cell constriction and cell intercalation, which are the result of cell intrinsic forces, but are also shaped passively by forces acting on the cells. The latter extrinsic forces can be produced either within the deforming tissue by the tissue-scale integration of intrinsic forces, or outside the tissue by other tissue movements or by fluid flows. Here we review the intrinsic and extrinsic forces that sculpt the epithelium of early Drosophila embryos, focusing on three conserved morphogenetic processes: tissue internalization, axis extension, and segment boundary formation. Finally, we look at how the actomyosin cytoskeleton forms force-generating structures that power these three morphogenetic events at the cell and the tissue scales.
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Monier B, Pélissier-Monier A, Brand AH, Sanson B. An actomyosin-based barrier inhibits cell mixing at compartmental boundaries in Drosophila embryos. Nat Cell Biol 2010; 12:60-9. [PMID: 19966783 PMCID: PMC4016768 DOI: 10.1038/ncb2005] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 11/12/2009] [Indexed: 12/30/2022]
Abstract
Partitioning tissues into compartments that do not intermix is essential for the correct morphogenesis of animal embryos and organs. Several hypotheses have been proposed to explain compartmental cell sorting, mainly differential adhesion, but also regulation of the cytoskeleton or of cell proliferation. Nevertheless, the molecular and cellular mechanisms that keep cells apart at boundaries remain unclear. Here we demonstrate, in early Drosophila melanogaster embryos, that actomyosin-based barriers stop cells from invading neighbouring compartments. Our analysis shows that cells can transiently invade neighbouring compartments, especially when they divide, but are then pushed back into their compartment of origin. Actomyosin cytoskeletal components are enriched at compartmental boundaries, forming cable-like structures when the epidermis is mitotically active. When MyoII (non-muscle myosin II) function is inhibited, including locally at the cable by chromophore-assisted laser inactivation (CALI), in live embryos, dividing cells are no longer pushed back, leading to compartmental cell mixing. We propose that local regulation of actomyosin contractibility, rather than differential adhesion, is the primary mechanism sorting cells at compartmental boundaries.
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Affiliation(s)
- Bruno Monier
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Anne Pélissier-Monier
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
- The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andrea H. Brand
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
- The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Bénédicte Sanson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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Lin N, Zhang C, Pang J, Zhou L. By design or by chance: cell death during Drosophila embryogenesis. Apoptosis 2009; 14:935-42. [PMID: 19466551 DOI: 10.1007/s10495-009-0360-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cell death plays an essential role during Drosophila embryogenesis. However, it remains an enigma as to what mechanisms determine (or select) the specific cells to be eliminated at a particular developmental stage. Is it mostly dependent on the lineage of the cell, signifying genetic predetermination, or is it due to the failure of a cell to compete for growth factors, which is more or less by chance? Recent developments in studying the molecular mechanism of cell death during Drosophila embryogenesis has provided much insight into our understanding of the relative importance of, and the interaction between, these two mechanisms in shaping the embryo.
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Affiliation(s)
- Nianwei Lin
- Department of Molecular Genetics and Microbiology, UF Shands Cancer Center, University of Florida, Gainesville, FL 32610-0232, USA
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Kessler T, Müller HAJ. Cleavage of Armadillo/beta-catenin by the caspase DrICE in Drosophila apoptotic epithelial cells. BMC DEVELOPMENTAL BIOLOGY 2009; 9:15. [PMID: 19232093 PMCID: PMC2657781 DOI: 10.1186/1471-213x-9-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Accepted: 02/20/2009] [Indexed: 11/24/2022]
Abstract
Background During apoptosis cells become profoundly restructured through concerted cleavage of cellular proteins by caspases. In epithelial tissues, apoptotic cells loose their apical/basal polarity and are extruded from the epithelium. We used the Drosophila embryo as a system to investigate the regulation of components of the zonula adherens during apoptosis. Since Armadillo/beta-catenin (Arm) is a major regulator of cadherin-mediated adhesion, we analyzed the mechanisms of Arm proteolysis in apoptosis. Results We define early and late apoptotic stages and find that early in apoptosis Dα-catenin remains relatively stable, while Arm and DE-cadherin protein levels are strongly reduced. Arm is cleaved by caspases in embryo extracts and we provide evidence that the caspase-3 homolog drICE cleaves Arm in vitro and in vivo. Cleavage by drICE creates a stable protein fragment that remains associated with the plasma membrane early in apoptosis. To further understand the role of caspase-mediated cleavage of Arm, we examined potential caspase cleavage sites and found that drICE cleaves Arm at a unique DQVD motif in the N-terminal domain of the protein. Mutation of the drICE cleavage site in Arm results in a protein that is not cleaved in vitro and in vivo. Furthermore we provide evidence that cleavage of Arm plays a role in the removal of DE-cadherin from the plasma membrane during apoptosis. Conclusion This study defines the specificity of caspase cleavage of Arm in Drosophila apoptotic cells. Our data suggest that N-terminal truncation of Arm by caspases is evolutionarily conserved and thus might provide a principal mechanism involved in the disassembly of adherens junctions during apoptosis.
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Affiliation(s)
- Thomas Kessler
- Institut für Genetik, Heinrich Heine Universität, Düsseldorf, Germany.
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Basolateral junctions utilize warts signaling to control epithelial-mesenchymal transition and proliferation crucial for migration and invasion of Drosophila ovarian epithelial cells. Genetics 2008; 178:1947-71. [PMID: 18430928 DOI: 10.1534/genetics.108.086983] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Fasciclin2 (Fas2) and Discslarge (Dlg) localize to the basolateral junction (BLJ) of Drosophila follicle epithelial cells and inhibit their proliferation and invasion. To identify a BLJ signaling pathway we completed a genomewide screen for mutants that enhance dlg tumorigenesis. We identified two genes that encode known BLJ scaffolding proteins, lethal giant larvae (lgl) and scribble (scrib), and several not previously associated with BLJ function, including warts (wts) and roughened eye (roe), which encode a serine-threonine kinase and a transcription factor, respectively. Like scrib, wts and roe also enhance Fas2 and lgl tumorigenesis. Further, scrib, wts, and roe block border cell migration, and cause noninvasive tumors that resemble dlg partial loss of function, suggesting that the BLJ utilizes Wts signaling to repress EMT and proliferation, but not motility. Apicolateral junction proteins Fat (Ft), Expanded (Ex), and Merlin (Mer) either are not involved in these processes, or have highly spatio-temporally restricted roles, diminishing their significance as upstream inputs to Wts in follicle cells. This is further indicated in that Wts targets, CyclinE and DIAP1, are elevated in Fas2, dlg, lgl, wts, and roe cells, but not Fat, ex, or mer cells. Thus, the BLJ appears to regulate epithelial polarity and dynamics not only as a localized scaffold, but also by communicating signals to the nucleus. Wts may be regulated by distinct junction inputs depending on developmental context.
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