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Latham ZD, Bermudez A, Hu JK, Lin NYC. Regulation of epithelial cell jamming transition by cytoskeleton and cell-cell interactions. BIOPHYSICS REVIEWS 2024; 5:041301. [PMID: 39416285 PMCID: PMC11479637 DOI: 10.1063/5.0220088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 09/16/2024] [Indexed: 10/19/2024]
Abstract
Multicellular systems, such as epithelial cell collectives, undergo transitions similar to those in inert physical systems like sand piles and foams. To remodel or maintain tissue organization during development or disease, these collectives transition between fluid-like and solid-like states, undergoing jamming or unjamming transitions. While these transitions share principles with physical systems, understanding their regulation and implications in cell biology is challenging. Although cell jamming and unjamming follow physics principles described by the jamming diagram, they are fundamentally biological processes. In this review, we explore how cellular processes and interactions regulate jamming and unjamming transitions. We begin with an overview of how these transitions control tissue remodeling in epithelial model systems and describe recent findings of the physical principles governing tissue solidification and fluidization. We then explore the mechanistic pathways that modulate the jamming phase diagram axes, focusing on the regulation of cell fluctuations and geometric compatibility. Drawing upon seminal works in cell biology, we discuss the roles of cytoskeleton and cell-cell adhesion in controlling cell motility and geometry. This comprehensive view illustrates the molecular control of cell jamming and unjamming, crucial for tissue remodeling in various biological contexts.
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Affiliation(s)
- Zoe D. Latham
- Bioengineering Department, UCLA, Los Angeles, California 90095, USA
| | | | - Jimmy K. Hu
- Authors to whom correspondence should be addressed: and
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2
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Xu W, Alpha KM, Zehrbach NM, Turner CE. Paxillin Promotes Breast Tumor Collective Cell Invasion through Maintenance of Adherens Junction Integrity. Mol Biol Cell 2021; 33:ar14. [PMID: 34851720 PMCID: PMC9236150 DOI: 10.1091/mbc.e21-09-0432] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Distant organ metastasis is linked to poor prognosis during cancer progression. The expression level of the focal adhesion adapter protein paxillin varies among different human cancers, but its role in tumor progression is unclear. Herein, we utilize a newly generated PyMT mammary tumor mouse model with conditional paxillin ablation in breast tumor epithelial cells, combined with in vitro 3D tumor organoids invasion analysis and 2D calcium switch assays, to assess the roles for paxillin in breast tumor cell invasion. Paxillin had little effect on primary tumor initiation and growth but is critical for the formation of distant lung metastasis. In paxillin-depleted 3D tumor organoids, collective cell invasion was substantially perturbed. Two-dimensional cell culture revealed paxillin-dependent stabilization of adherens junctions (AJ). Mechanistically, paxillin is required for AJ assembly through facilitating E-cadherin endocytosis and recycling and HDAC6-mediated microtubule acetylation. Furthermore, Rho GTPase activity analysis and rescue experiments with a RhoA activator or Rac1 inhibitor suggest paxillin is potentially regulating the E-cadherin-dependent junction integrity and contractility through control of the balance of RhoA and Rac1 activities. Together, these data highlight new roles for paxillin in the regulation of cell-cell adhesion and collective tumor cell migration to promote the formation of distance organ metastases. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text].
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Affiliation(s)
- Weiyi Xu
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA
| | - Kyle M Alpha
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA
| | - Nicholas M Zehrbach
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA
| | - Christopher E Turner
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA
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3
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Blackie L, Tozluoglu M, Trylinski M, Walther RF, Schweisguth F, Mao Y, Pichaud F. A combination of Notch signaling, preferential adhesion and endocytosis induces a slow mode of cell intercalation in the Drosophila retina. Development 2021; 148:264928. [PMID: 33999996 PMCID: PMC8180261 DOI: 10.1242/dev.197301] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 04/09/2021] [Indexed: 12/25/2022]
Abstract
Movement of epithelial cells in a tissue occurs through neighbor exchange and drives tissue shape changes. It requires intercellular junction remodeling, a process typically powered by the contractile actomyosin cytoskeleton. This has been investigated mainly in homogeneous epithelia, where intercalation takes minutes. However, in some tissues, intercalation involves different cell types and can take hours. Whether slow and fast intercalation share the same mechanisms remains to be examined. To address this issue, we used the fly eye, where the cone cells exchange neighbors over ∼10 h to shape the lens. We uncovered three pathways regulating this slow mode of cell intercalation. First, we found a limited requirement for MyosinII. In this case, mathematical modeling predicts an adhesion-dominant intercalation mechanism. Genetic experiments support this prediction, revealing a role for adhesion through the Nephrin proteins Roughest and Hibris. Second, we found that cone cell intercalation is regulated by the Notch pathway. Third, we show that endocytosis is required for membrane removal and Notch activation. Taken together, our work indicates that adhesion, endocytosis and Notch can direct slow cell intercalation during tissue morphogenesis.
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Affiliation(s)
- Laura Blackie
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK.,MRC London Institute of Medical Sciences (LMS), London W12 0NN, UK
| | - Melda Tozluoglu
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK
| | - Mateusz Trylinski
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK.,Department of Developmental and Stem Cell Biology, Pasteur Institute, F-75015 Paris, France
| | - Rhian F Walther
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK
| | - François Schweisguth
- Department of Developmental and Stem Cell Biology, Pasteur Institute, F-75015 Paris, France.,CNRS, UMR3738, F-75015 Paris, France
| | - Yanlan Mao
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK.,Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
| | - Franck Pichaud
- MRC Laboratory for Molecular Cell Biology (LMCB), University College London, London WC1E 6BT, UK.,Institute for the Physics of Living Systems, University College London, London WC1E 6BT, UK
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4
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Ma Z, Li P, Hu X, Song H. Polarity protein Canoe mediates overproliferation via modulation of JNK, Ras-MAPK and Hippo signalling. Cell Prolif 2018; 52:e12529. [PMID: 30328653 PMCID: PMC6430484 DOI: 10.1111/cpr.12529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 08/20/2018] [Accepted: 08/28/2018] [Indexed: 02/06/2023] Open
Abstract
Objectives Over the past decade an intriguing connection between cell polarity and tumorigenesis has emerged. Multiple core components of the junction complexes that help to form and maintain cell polarity display both pro‐ and anti‐tumorigenic functions in a context‐dependent manner, with the underlying mechanisms poorly understood. Materials and Methods With transgenic fly lines that overexpress or knock down specific signalling components, we perform genetic analysis to investigate the precise role of the polarity protein Canoe (Cno) in tumorigenesis and the downstream pathways. Results We show that overexpression of cno simultaneously activates JNK and Ras‐MEK‐ERK signalling, resulting in mixed phenotypes of both overproliferation and cell death in the Drosophila wing disc. Moderate alleviation of JNK activation eliminates the effect of Cno on cell death, leading to organ overgrowth and cell migration that mimic the formation and invasion of tumours. In addition, we find that the Hippo pathway acts downstream of JNK and Ras signalling to mediate the effect of Cno on cell proliferation. Conclusions Our work reveals an oncogenic role of Cno and creates a new type of Drosophila tumour model for cancer research.
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Affiliation(s)
- Zhiwei Ma
- Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ping Li
- Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xingjie Hu
- School of Public Health, Guangzhou Medical University, Guangdong, China
| | - Haiyun Song
- Shanghai Institute of Nutrition and Health, Shanghai Institutes for Biological Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China.,School of Public Health, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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5
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Rewiring cell polarity signaling in cancer. Oncogene 2014; 34:939-50. [PMID: 24632617 DOI: 10.1038/onc.2014.59] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 02/07/2014] [Accepted: 02/11/2014] [Indexed: 02/08/2023]
Abstract
Disrupted cell polarity is a feature of epithelial cancers. The Crumbs, Par and Scribble polarity complexes function to specify and maintain apical and basolateral membrane domains, which are essential to organize intracellular signaling pathways that maintain epithelial homeostasis. Disruption of apical-basal polarity proteins facilitates rewiring of oncogene and tumor suppressor signaling pathways to deregulate proliferation, apoptosis, invasion and metastasis. Moreover, apical-basal polarity integrates intracellular signaling with the microenvironment by regulating metabolic signaling, extracellular matrix remodeling and tissue level organization. In this review, we discuss recent advances in our understanding of how polarity proteins regulate diverse signaling pathways throughout cancer progression from initiation to metastasis.
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6
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Buss LW, Anderson C, Bolton EW. Muscular anatomy of the Podocoryna carnea hydrorhiza. PLoS One 2013; 8:e72221. [PMID: 23967288 PMCID: PMC3743812 DOI: 10.1371/journal.pone.0072221] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 07/07/2013] [Indexed: 11/18/2022] Open
Abstract
The muscular anatomy of the athecate hydroid Podocoryna carnea hydrorhiza is elucidated. The polyp-stolon junction is characterized by an opening, here called the chloe, in the otherwise continuous hydrorhizal perisarc. The chloe is elliptical when the polyp first arises, but takes on a more complex outline as multiple stolons anastomose to communicate with that polyp. Surrounding the polyp base are spots, here called anchors, which autofluoresce at the same wavelengths as perisarc and which, like perisarc, contain chitin as assessed by Calcofluor White, Congo Red and wheat germ agglutinin staining. Anchors remain after living tissues are digested using KOH. Collagen IV staining indicates that the mesoglea is pegged to the anchors and rhodamine phallodin staining detects cytoskeletal F-actin fibers of the basal epidermis surrounding the anchors. Longitudinal muscle fibers of the polyp broaden at the polyp base and are inserted into the mesoglea of the underlying stolon, but were neither observed to extend along the stolonal axis nor to attach to the anchors. Circular muscular fibers of the polyp extend into stolons as a dense collection of strands running along the proximal-distal axis of the stolon. These gastrodermal axial muscular fibers extend to the stolon tip. Epidermal cells at the stolon tip and the polyp bud display a regular apical latticework of F-actin staining. A similar meshwork of F-actin staining was found in the extreme basal epidermis of all stolons. Immunohistochemical staining for tubulin revealed nerves at stolon tips, but at no other hydrorhizal locations. These studies bear on the mechanisms by which the stolon tip and polyp bud pulsate, the manner in which the stolon lumen closes, and on the developmental origin of the basal epidermis of the hydrorhiza.
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Affiliation(s)
- Leo W Buss
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut, United States of America.
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7
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Wells RE, Barry JD, Warrington SJ, Cuhlmann S, Evans P, Huber W, Strutt D, Zeidler MP. Control of tissue morphology by Fasciclin III-mediated intercellular adhesion. Development 2013; 140:3858-68. [PMID: 23946443 PMCID: PMC3915571 DOI: 10.1242/dev.096214] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Morphogenesis is dependent on the orchestration of multiple developmental processes to generate mature functional organs. However, the signalling pathways that coordinate morphogenesis and the mechanisms that translate these signals into tissue shape changes are not well understood. Here, we demonstrate that changes in intercellular adhesion mediated by the transmembrane protein Fasciclin III (FasIII) represent a key mediator of morphogenesis. Using the embryonic Drosophila hindgut as an in vivo model for organogenesis, we show that the tightening of hindgut curvature that normally occurs between embryonic stage 12 and 15 to generate the characteristic shepherd’s crook shape is dependent on localised JAK/STAT pathway activation. This localised pathway activity drives the expression of FasIII leading to its subcellular lateralisation at a stage before formation of septate junctions. Additionally, we show that JAK/STAT- and FasIII-dependent morphogenesis also regulates folds within the third instar wing imaginal disc. We show that FasIII forms homophilic intercellular interactions that promote intercellular adhesion in vivo and in cultured cells. To explore these findings, we have developed a mathematical model of the developing hindgut, based on the differential interfacial tension hypothesis (DITH) linking intercellular adhesion and localised surface tension. Our model suggests that increased intercellular adhesion provided by FasIII can be sufficient to drive the tightening of tube curvature observed. Taken together, these results identify a conserved molecular mechanism that directly links JAK/STAT pathway signalling to intercellular adhesion and that sculpts both tubular and planar epithelial shape.
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Affiliation(s)
- Richard E Wells
- MRC Centre for Developmental and Biomedical Genetics, The University of Sheffield, Firth Court, Sheffield S10 2TN, UK
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8
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Small GTPase Rho regulates R-cadherin through Dia1/profilin-1. Cell Signal 2012; 24:2102-10. [DOI: 10.1016/j.cellsig.2012.07.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/12/2012] [Accepted: 07/16/2012] [Indexed: 12/20/2022]
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Loosley AJ, Tang JX. Stick-slip motion and elastic coupling in crawling cells. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 86:031908. [PMID: 23030945 DOI: 10.1103/physreve.86.031908] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Indexed: 06/01/2023]
Abstract
Crawling cells exhibit a variety of cell shape dynamics, ranging from complex ruffling and bubbling to oscillatory protrusion and retraction. Periodic shape changes during cell migration are recorded in fast-moving fish epithelial keratocytes where sticking and slipping at opposite sides of the cell's broad trailing edge generate bipedal locomotion. Barnhart et al. [Biophys. J. 98, 933 (2010)] recently proposed a mechanical spring model specifically designed to capture bipedal locomotion in these cells. We extend their model by benchmarking the dynamics of four mechanical configurations against those of crawling keratocytes. Our analysis shows that elastic coupling to the cell nucleus is necessary to generate its lateral motion. We select one configuration to study the effects of cell elasticity, size, and aspect ratio on crawling dynamics. This configuration predicts that shape dynamics are highly dependent on the lamellipodial elasticity but less sensitive to elasticity at the trailing edge. The model predicts a wide range of dynamics seen in actual crawling keratocytes, including coherent bipedal, coherent nonbipedal, and decoherent motions. This work highlights how the dynamical behavior of crawling cells can be derived from mechanical properties through which biochemical factors may operate to regulate cellular locomotion.
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Affiliation(s)
- Alex J Loosley
- Department of Physics, Brown University, 182 Hope Street, Providence, Rhode Island 02912, USA.
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10
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Cell adhesion in Drosophila: versatility of cadherin and integrin complexes during development. Curr Opin Cell Biol 2012; 24:702-12. [PMID: 22938782 DOI: 10.1016/j.ceb.2012.07.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/16/2012] [Accepted: 07/26/2012] [Indexed: 01/22/2023]
Abstract
We highlight recent progress in understanding cadherin and integrin function in the model organism Drosophila. New functions for these adhesion receptors continue to be discovered in this system, emphasising the importance of cell adhesion within the developing organism and showing that the requirement for cell adhesion changes between cell types. New ways to control adhesion have been discovered, including controlling the expression and recruitment of adhesion components, their posttranslational modification, recycling and turnover. Importantly, even ubiquitous adhesion components can function differently in distinct cellular contexts.
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11
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Nowak RB, Fowler VM. Tropomodulin 1 constrains fiber cell geometry during elongation and maturation in the lens cortex. J Histochem Cytochem 2012; 60:414-27. [PMID: 22473940 DOI: 10.1369/0022155412440881] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Lens fiber cells exhibit a high degree of hexagonal packing geometry, determined partly by tropomodulin 1 (Tmod1), which stabilizes the spectrin-actin network on lens fiber cell membranes. To ascertain whether Tmod1 is required during epithelial cell differentiation to fiber cells or during fiber cell elongation and maturation, the authors quantified the extent of fiber cell disorder in the Tmod1-null lens and determined locations of disorder by confocal microscopy and computational image analysis. First, nearest neighbor analysis of fiber cell geometry in Tmod1-null lenses showed that disorder is confined to focal patches. Second, differentiating epithelial cells at the equator aligned into ordered meridional rows in Tmod1-null lenses, with disordered patches first observed in elongating fiber cells. Third, as fiber cells were displaced inward in Tmod1-null lenses, total disordered area increased due to increased sizes (but not numbers) of individual disordered patches. The authors conclude that Tmod1 is required first to coordinate fiber cell shapes and interactions during tip migration and elongation and second to stabilize ordered fiber cell geometry during maturation in the lens cortex. An unstable spectrin-actin network without Tmod1 may result in imbalanced forces along membranes, leading to fiber cell rearrangements during elongation, followed by propagation of disorder as fiber cells mature.
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Padovano V, Lucibello I, Alari V, Della Mina P, Crespi A, Ferrari I, Recagni M, Lattuada D, Righi M, Toniolo D, Villa A, Pietrini G. The POF1B candidate gene for premature ovarian failure regulates epithelial polarity. J Cell Sci 2012; 124:3356-68. [PMID: 21940798 DOI: 10.1242/jcs.088237] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
POF1B is a candidate gene for premature ovarian failure (POF); it is mainly expressed in polarised epithelial tissues, but its function in these tissues and the relationship with the disorder are unknown. Here we show colocalisation of POF1B with markers of both adherens and tight junctions in human jejunum. The tight junction localisation was maintained by the human POF1B stably expressed in the MDCK polarised epithelial cell line, whereas it was lost by the POF1B R329Q variant associated with POF. Localisation of apico-basal polarity markers and ultrastructure of the tight junctions were maintained in cells expressing the mutant. However, tight junction assembly was altered, cells were dysmorphic and the monolayer organisation was also altered in three-dimensional culture systems. Moreover, cells expressing the POF1B R329Q variant showed defects in ciliogenesis and cystogenesis as a result of misorientation of primary cilia and mitotic division. All of these defects were explained by interference of the mutant with the content and organisation of F-actin at the junctions. A role for POF1B in the regulation of the actin cytoskeleton was further verified by shRNA silencing of the endogenous protein in human intestinal Caco-2 cells. Taken together, these data indicate that localisation of POF1B to tight junctions has a key role in the organisation of epithelial monolayers by regulating the actin cytoskeleton.
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Affiliation(s)
- Valeria Padovano
- Department of Pharmacology, Medical School, Università degli Studi di Milano, 20129 Milan, Italy
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13
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Sazonova OV, Lee KL, Isenberg BC, Rich CB, Nugent MA, Wong JY. Cell-cell interactions mediate the response of vascular smooth muscle cells to substrate stiffness. Biophys J 2011; 101:622-30. [PMID: 21806930 DOI: 10.1016/j.bpj.2011.06.051] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/27/2011] [Accepted: 06/21/2011] [Indexed: 01/08/2023] Open
Abstract
The vessel wall experiences progressive stiffening with age and the development of cardiovascular disease, which alters the micromechanical environment experienced by resident vascular smooth muscle cells (VSMCs). In vitro studies have shown that VSMCs are sensitive to substrate stiffness, but the exact molecular mechanisms of their response to stiffness remains unknown. Studies have also shown that cell-cell interactions can affect mechanotransduction at the cell-substrate interface. Using flexible substrates, we show that the expression of proteins associated with cell-matrix adhesion and cytoskeletal tension is regulated by substrate stiffness, and that an increase in cell density selectively attenuates some of these effects. We also show that cell-cell interactions exert a strong effect on cell morphology in a substrate-stiffness dependent manner. Collectively, the data suggest that as VSMCs form cell-cell contacts, substrate stiffness becomes a less potent regulator of focal adhesion signaling. This study provides insight into the mechanisms by which VSMCs respond to the mechanical environment of the blood vessel wall, and point to cell-cell interactions as critical mediators of VSMC response to vascular injury.
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Affiliation(s)
- Olga V Sazonova
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
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Koh SWM. Corneal endothelial autocrine trophic factor VIP in a mechanism-based strategy to enhance human donor cornea preservation for transplantation. Exp Eye Res 2011; 95:48-53. [PMID: 22036689 DOI: 10.1016/j.exer.2011.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 10/03/2011] [Accepted: 10/14/2011] [Indexed: 12/13/2022]
Abstract
Vasoactive intestinal peptide (VIP) and ciliary neurotrophic factor (CNTF) are identified as autocrines of human corneal endothelial (CE) cells working in concert to maintain the differentiated state and promote the survival of the corneal endothelium. From VIP gene knockdown study, endogenous VIP is shown to maintain the level of the differentiation marker, the adhesion molecule N-cadherin, CE cell size, shape, and retention, in situ in the human donor corneoscleral explants. Exogenous VIP protects the corneal endothelium against the killing effect of oxidative stress, in part by upholding ATP levels in CE cells dying of oxidative stress-induced injury, allowing them to die of an apoptotic death instead of an acute necrotic one. The switch from the acute necrosis to the programmed cell death (apoptosis) may have allowed the injured CE cell to be rescued by the VIP-upregulated pathways, including those of Bcl-2 and N-cadherin, and resulted in long-term CE cell survival. The endogenous VIP in CE cells is upregulated by CNTF, which is released by CE cells surviving the oxidative stress. The CNTF receptor (CNTFRα) is expressed in CE cells in human donor corneoscleral explant and gradually becomes lost during corneal storage. VIP treatment (10(-8) M, 37 °C, 30 min) prior to storage of freshly dissected human donor corneoscleral explants increases their CE cell CNTFRα level and responsiveness to CNTF in upregulating the gap junctional protein connexin-43 expression. VIP treatment of both fresh and preserved corneoscleral explants reduces CE damage in the corneoscleral explants and in the corneal buttons trephined from them. CE cell loss is a critical risk factor in corneal graft failure at any time in the life of the graft, which can be as late as 5-10 years after an initially successful transplant. A new procedure, Descemet's stripping automated endothelial keratoplasty (DSAEK), which is superior to the traditional full thickness transplantation in many aspects, nevertheless subjects the corneal endothelium to extensive mechanical forces, resulting in even more pronounced CE cell loss than the traditional technique. Whereas it is known that cells transduce mechanical stress through N-cadherin, stimulation of the N-cadherin pathway increases the anti-apoptotic protein Bcl-2 expression. Since N-cadherin and Bcl-2 in the corneal endothelium are both upregulated by VIP, we aim to strengthen the CE sheet by VIP treatments of the corneoscleral explants for full thickness traditional corneal transplantation and pre-cut corneas for DSAEK.
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Affiliation(s)
- Shay-Whey Margaret Koh
- Department of Ophthalmology & Visual Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
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15
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Machado MCR, Octacilio-Silva S, Costa MSA, Ramos RGP. rst transcriptional activity influences kirre mRNA concentration in the Drosophila pupal retina during the final steps of ommatidial patterning. PLoS One 2011; 6:e22536. [PMID: 21857931 PMCID: PMC3152562 DOI: 10.1371/journal.pone.0022536] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 06/23/2011] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Drosophila retinal architecture is laid down between 24-48 hours after puparium formation, when some of the still uncommitted interommatidial cells (IOCs) are recruited to become secondary and tertiary pigment cells while the remaining ones undergo apoptosis. This choice between survival and death requires the product of the roughest (rst) gene, an immunoglobulin superfamily transmembrane glycoprotein involved in a wide range of developmental processes. Both temporal misexpression of Rst and truncation of the protein intracytoplasmic domain, lead to severe defects in which IOCs either remain mostly undifferentiated and die late and erratically or, instead, differentiate into extra pigment cells. Intriguingly, mutants not expressing wild type protein often have normal or very mild rough eyes. METHODOLOGY/PRINCIPAL FINDINGS By using quantitative real time PCR to examine rst transcriptional dynamics in the pupal retina, both in wild type and mutant alleles we showed that tightly regulated temporal changes in rst transcriptional rate underlie its proper function during the final steps of eye patterning. Furthermore we demonstrated that the unexpected wild type eye phenotype of mutants with low or no rst expression correlates with an upregulation in the mRNA levels of the rst paralogue kin-of-irre (kirre), which seems able to substitute for rst function in this process, similarly to their role in myoblast fusion. This compensatory upregulation of kirre mRNA levels could be directly induced in wild type pupa upon RNAi-mediated silencing of rst, indicating that expression of both genes is also coordinately regulated in physiological conditions. CONCLUSIONS/SIGNIFICANCE These findings suggest a general mechanism by which rst and kirre expression could be fine tuned to optimize their redundant roles during development and provide a clearer picture of how the specification of survival and apoptotic fates by differential cell adhesion during the final steps of retinal morphogenesis in insects are controlled at the transcriptional level.
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Affiliation(s)
- Maiaro Cabral Rosa Machado
- Departmento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Shirlei Octacilio-Silva
- Departmento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Mara Silvia A. Costa
- Departmento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Ricardo Guelerman P. Ramos
- Departmento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
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Shi J, Sun M, Vogt PK. Smooth muscle α-actin is a direct target of PLZF: effects on the cytoskeleton and on susceptibility to oncogenic transformation. Oncotarget 2011; 1:9-21. [PMID: 20634973 PMCID: PMC2903758 DOI: 10.18632/oncotarget.104] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Changes in cell morphology and rearrangements of the actin cytoskeleton are common features accompanying cell transformation induced by various oncogenes. In this study, we show that promyelocytic leukemia zinc finger protein (PLZF) binds to the promoter of smooth muscle α-actin, reducing mRNA and protein levels encoded by this gene and resulting in a reorganization of the actin cytoskeleton. In cultures of chicken embryo fibroblasts (CEF), this effect on α-actin expression is correlated with a change in cellular phenotype from spindle shaped to polygonal and flattened. This morphological change is dependent on Ras function. The polygonal, flattened CEF show a high degree of resistance to the transforming activity of several oncoproteins. Our results support the conclusion that reorganization of the actin cytoskeleton plays an important role in tumor suppression by PLZF.
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Affiliation(s)
- Jin Shi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
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17
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Yang XY, Edelmann RE, Oris JT. Suspended C60 nanoparticles protect against short-term UV and fluoranthene photo-induced toxicity, but cause long-term cellular damage in Daphnia magna. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2010; 100:202-210. [PMID: 19854522 DOI: 10.1016/j.aquatox.2009.08.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 08/25/2009] [Accepted: 08/28/2009] [Indexed: 05/28/2023]
Abstract
The increased production of nanotechnology materials is a potential source of nano-sized particles (NSPs) in aquatic ecosystems. Meanwhile, polycyclic aromatic hydrocarbons (PAHs), in the presence of ecologically relevant levels of ultraviolet radiation (UV), can be acutely toxic to aquatic species including fish and invertebrates. Considering that suspended carbon-based NSPs (e.g., C60 fullerenes) may act in similar ways as dissolved organic matter (DOM) by altering the bioavailability of PAHs, the objective of this research was to determine the effect of suspended C60 on the photo-induced toxicity of fluoranthene. Transmission electron microscopy indicated that the presence of C60 protected cellular components (e.g., mitochondria, microvilli, and basal infoldings) in organisms exposed to UV and fluoranthene phototoxicity in short-term exposures. However, we found that long-term exposure (21d) of low-level C60 caused significant cellular damage in the Daphnia magna alimentary canal. This paper highlights the importance of examining the interactions between existing stressors and nanoparticles in the aquatic environment.
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Affiliation(s)
- X Y Yang
- Department of Zoology, Miami University, Oxford, OH 45056, USA
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18
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Cavey M, Lecuit T. Molecular bases of cell-cell junctions stability and dynamics. Cold Spring Harb Perspect Biol 2010; 1:a002998. [PMID: 20066121 DOI: 10.1101/cshperspect.a002998] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Epithelial cell-cell junctions are formed by apical adherens junctions (AJs), which are composed of cadherin adhesion molecules interacting in a dynamic way with the cortical actin cytoskeleton. Regulation of cell-cell junction stability and dynamics is crucial to maintain tissue integrity and allow tissue remodeling throughout development. Actin filament turnover and organization are tightly controlled together with myosin-II activity to produce mechanical forces that drive the assembly, maintenance, and remodeling of AJs. In this review, we will discuss these three distinct stages in the lifespan of cell-cell junctions, using several developmental contexts, which illustrate how mechanical forces are generated and transmitted at junctions, and how they impact on the integrity and the remodeling of cell-cell junctions.
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Affiliation(s)
- Matthieu Cavey
- IBDML, UMR CNRS-Université de la Méditerranée, Marseille, France
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19
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Giagtzoglou N, Ly CV, Bellen HJ. Cell adhesion, the backbone of the synapse: "vertebrate" and "invertebrate" perspectives. Cold Spring Harb Perspect Biol 2010; 1:a003079. [PMID: 20066100 DOI: 10.1101/cshperspect.a003079] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Synapses are asymmetric intercellular junctions that mediate neuronal communication. The number, type, and connectivity patterns of synapses determine the formation, maintenance, and function of neural circuitries. The complexity and specificity of synaptogenesis relies upon modulation of adhesive properties, which regulate contact initiation, synapse formation, maturation, and functional plasticity. Disruption of adhesion may result in structural and functional imbalance that may lead to neurodevelopmental diseases, such as autism, or neurodegeneration, such as Alzheimer's disease. Therefore, understanding the roles of different adhesion protein families in synapse formation is crucial for unraveling the biology of neuronal circuit formation, as well as the pathogenesis of some brain disorders. The present review summarizes some of the knowledge that has been acquired in vertebrate and invertebrate genetic model organisms.
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Affiliation(s)
- Nikolaos Giagtzoglou
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA.
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BMP/SMAD signaling regulates the cell behaviors that drive the initial dorsal-specific regional morphogenesis of the otocyst. Dev Biol 2010; 347:369-81. [PMID: 20837004 DOI: 10.1016/j.ydbio.2010.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 09/02/2010] [Accepted: 09/02/2010] [Indexed: 12/20/2022]
Abstract
During development of the otocyst, regional morphogenesis establishes a dorsal vestibular chamber and a ventral auditory chamber, which collectively constitute the membranous labyrinth of the inner ear. We identified the earliest morphogenetic event heralding the formation of the vestibular chamber, a rapid thinning and expansion of the dorsolateral wall of the otocyst, and showed that this process is generated by changes in otocyst cell shape from columnar to squamous, as opposed to changes in other cell behaviors, such as localized changes in cell proliferation or cell death. Moreover, we showed that thinning and expansion of the dorsolateral otocyst is regulated by BMP/SMAD signaling, which is both sufficient and necessary for localized thinning and expansion. Finally, we showed that BMP/SMAD signaling causes fragmentation of E-cadherin in the dorsolateral otocyst, occurring concomitantly with cell shape change, suggesting that BMP/SMAD signaling regulates cell-cell adhesion during the initial morphogenesis of the otocyst epithelium. Collectively, our results show that BMP signaling via SMADs regulates the cell behaviors that drive the initial dorsal-specific morphogenesis of the otocyst, providing new information about how regional morphogenesis of a complex organ rudiment, the developing membranous labyrinth, is initiated.
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Levine B, Hackney JF, Bergen A, Dobens L, Truesdale A, Dobens L. Opposing interactions between Drosophila cut and the C/EBP encoded by slow border cells direct apical constriction and epithelial invagination. Dev Biol 2010; 344:196-209. [PMID: 20450903 DOI: 10.1016/j.ydbio.2010.04.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 04/26/2010] [Accepted: 04/27/2010] [Indexed: 12/29/2022]
Abstract
Stage 10 of Drosophila oogenesis can be subdivided into stages 10A and 10B based on a change in the morphology of the centripetal follicle cells (FC) from a columnar to an apically constricted shape. This coordinated cell shape change drives epithelial cell sheet involution between the oocyte and nurse cell complex which patterns the operculum structure of the mature eggshell. We have shown previously that proper centripetal FC migration requires transient expression of the C/EBP encoded by slow border cells (slbo) at 10A, due in part to Notch activation followed by slbo autorepression (Levine et al., 2007). Here we show that decreased slbo expression in the centripetal FC coincides with increased expression of the transcription factor Cut, a Cut/Cux/CDP family member, at 10B. The 10A/10B temporal switch from Slbo to Cut expression is refined by both cross repression between Slbo and Cut, Slbo auto repression and Cut auto activation. High Cut levels are necessary and sufficient to direct polarized, supracellular accumulation of Actin, DE-cadherin and Armadillo associated with apical constriction of the centripetal FC. Separately, Slbo in the border cell rosette and Cut in the pole cells have antagonistic interactions to restrict Fas2 accumulation to the pole cells, which is important for proper border cell migration. The opposing effects of Cut and Slbo in these two tissues reflect the opposing interactions between their respective mammalian homologs CAAT Displacement Protein (CDP; now CUX1) and CAAT Enhancer Binding Protein (C/EBP) in tissue culture.
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Affiliation(s)
- Benjamin Levine
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA
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22
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Dose-dependent modulation of HIF-1alpha/sima controls the rate of cell migration and invasion in Drosophila ovary border cells. Oncogene 2009; 29:1123-34. [PMID: 19966858 DOI: 10.1038/onc.2009.407] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The role of the hypoxic response during metastasis was analysed in migrating border cells of the Drosophila ovary. Acute exposure to 1% O(2) delayed or blocked border cell migration (BCM), whereas prolonged exposure resulted in the first documented accelerated BCM phenotype. Similarly, manipulating the expression levels of sima, the Drosophila hypoxia-inducible factor (HIF)-1alpha ortholog, revealed that Sima can either block or restore BCM in a dose-dependent manner. In contrast, over-expression of Vhl (Drosophila von Hippel-Lindau) generated a range of phenotypes, including blocked, delayed and accelerated BCM, whereas over-expression of hph (Drosophila HIF prolyl hydroxylase) only accelerated BCM. Mosaic clone analysis of sima or tango (HIF-1beta ortholog) mutants revealed that cells lacking Hif-1 transcriptional activity were preferentially detected in the leading cell position of the cluster, resulting in either a delay or acceleration of BCM. Moreover, in sima mutant cell clones, there was reduced expression of nuclear slow border cells (Slbo) and basolateral DE-cadherin, proteins essential for proper BCM. These results show that Sima levels define the rate of BCM in part through regulation of Slbo and DE-cadherin, and suggest that dynamic regulation of Hif-1 activity is necessary to maintain invasive potential of migrating epithelial cells.
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Nowak RB, Fischer RS, Zoltoski RK, Kuszak JR, Fowler VM. Tropomodulin1 is required for membrane skeleton organization and hexagonal geometry of fiber cells in the mouse lens. ACTA ACUST UNITED AC 2009; 186:915-28. [PMID: 19752024 PMCID: PMC2753162 DOI: 10.1083/jcb.200905065] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hexagonal packing geometry is a hallmark of close-packed epithelial cells in metazoans. Here, we used fiber cells of the vertebrate eye lens as a model system to determine how the membrane skeleton controls hexagonal packing of post-mitotic cells. The membrane skeleton consists of spectrin tetramers linked to actin filaments (F-actin), which are capped by tropomodulin1 (Tmod1) and stabilized by tropomyosin (TM). In mouse lenses lacking Tmod1, initial fiber cell morphogenesis is normal, but fiber cell hexagonal shapes and packing geometry are not maintained as fiber cells mature. Absence of Tmod1 leads to decreased gammaTM levels, loss of F-actin from membranes, and disrupted distribution of beta2-spectrin along fiber cell membranes. Regular interlocking membrane protrusions on fiber cells are replaced by irregularly spaced and misshapen protrusions. We conclude that Tmod1 and gammaTM regulation of F-actin stability on fiber cell membranes is critical for the long-range connectivity of the spectrin-actin network, which functions to maintain regular fiber cell hexagonal morphology and packing geometry.
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Affiliation(s)
- Roberta B Nowak
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Edwards GO, Bazou D, Kuznetsova LA, Coakley WT. Cell Adhesion Dynamics and Actin Cytoskeleton Reorganization in HepG2 Cell Aggregates. ACTA ACUST UNITED AC 2009; 14:9-20. [PMID: 17453827 DOI: 10.1080/15419060701224849] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The temporal dependence of cytoskeletal remodelling on cell-cell contact in HepG2 cells has been established here. Cell-cell contact occurred in an ultrasound standing wave trap designed to form and levitate a 2-D cell aggregate, allowing intercellular adhesive interactions to proceed, free from the influences of solid substrata. Membrane spreading at the point of contact and change in cell circularity reached 50% of their final values within 2.2 min of contact. Junctional F-actin increased at the interface but lagged behind membrane spreading, reaching 50% of its final value in 4.4 min. Aggregates had good mechanical stability after 15 min in the trap. The implication of this temporal dependence on the sequential progress of adhesion processes is discussed. These results provide insight into how biomimetic cell aggregates with some liver cell functions might be assembled in a systematic, controlled manner in a 3-D ultrasound trap.
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Affiliation(s)
- Gareth Owain Edwards
- Cardiff School of Biosciences, Main Building, Cardiff University, Cardiff, Wales, UK.
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25
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Hammerschmidt M, Wedlich D. Regulated adhesion as a driving force of gastrulation movements. Development 2009; 135:3625-41. [PMID: 18952908 DOI: 10.1242/dev.015701] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent data have reinforced the fundamental role of regulated cell adhesion as a force that drives morphogenesis during gastrulation. As we discuss, cell adhesion is required for all modes of gastrulation movements in all organisms. It can even be instructive in nature, but it must be tightly and dynamically regulated. The picture that emerges from the recent findings that we review here is that different modes of gastrulation movements use the same principles of adhesion regulation, while adhesion molecules themselves coordinate the intra- and extracellular changes required for directed cell locomotion.
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Mogi A, Ichikawa H, Matsumoto C, Hieda T, Tomotsune D, Sakaki S, Yamada S, Sasaki K. The method of mouse embryoid body establishment affects structure and developmental gene expression. Tissue Cell 2008; 41:79-84. [PMID: 18722634 DOI: 10.1016/j.tice.2008.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 06/30/2008] [Accepted: 06/30/2008] [Indexed: 11/15/2022]
Abstract
To investigate formation of the three primary germ layers in mouse embryoid bodies (EBs), we observed changes in structure and gene expression over a 7-day culture period. We compared these changes using two methods for EB formation: hanging drop (HD) and static suspension culture (SSC). Light microscopy showed that a stratified columnar epithelial layer developed on the surface of EBs formed using the HD method. From Day 3 in culture, ultrastructural changes occurred in the aligned cellular membranes. Condensation of actin filaments was followed by formation of complicated adherent junctions and dilatation of intercellular canaliculi containing well-developed microvilli. These changes were more marked in EBs formed by the HD method than the SSC method. On Day 5 of culture, Brachyury gene expression, a marker for mesoderm formation, was detected only with the HD method. Nestin, an ectoderm marker, and Foxa2, an endoderm marker, were expressed with both methods. These results suggest that in EBs formed with the HD method, actin formation and Brachyury gene expression mark the transition from two to three primary germ layers. Additionally, the HD method promotes more rapid and complete development of mouse EBs than does the SSC method. While the SSC method is simple and easy to use, it needs improvement to form more complete EBs.
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Affiliation(s)
- A Mogi
- Department of Anatomy and Organ Technology, Shinshu University School of Medicine, Matsumoto 390-8621, Japan.
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Qi J, Chi L, Labeit S, Banes AJ. Nuclear localization of the titin Z1Z2Zr domain and role in regulating cell proliferation. Am J Physiol Cell Physiol 2008; 295:C975-85. [PMID: 18684985 DOI: 10.1152/ajpcell.90619.2007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Titin (also called connectin) is a major protein in sarcomere assembly as well as providing elastic return of the sarcomere postcontraction in cardiac and striated skeletal muscle tissues. In addition, it has been speculated that titin is associated with nuclear functions, including chromosome and spindle formation, and regulation of muscle gene expression. In the present study, a short isoform of titin was detected in a human osteoblastic cell line, MG-63 cells, by both immunostaining and Western blot analysis. Confocal images of titin staining showed both cytoplasmic and nuclear localization in a punctate pattern. Therefore, we hypothesized that human titin may contain a nuclear localization signal (NLS). A functional NLS, 200-PAKKTKT-206, located in a low-complexity, titin-specific region between Z2 and Z repeats, was found by sequentially deleting segments of the NH(2)-terminal sequence in conjunction with an enhanced green fluorescent protein reporter system and confirmed by site-directed mutagenesis. Overexpression of titin's amino terminal fragment (Z1Z2Zr) in human osteoblasts (MG-63) increased cell proliferation by activating the Wnt/beta-catenin pathway. RT-PCR screens of tissue panels demonstrated that residues 1-206 were ubiquitously expressed at low levels in all tissues and cell types analyzed. Our data implicate a dual role for titin's amino terminal region, i.e., a novel nuclear function promoting cell division in addition to its known structural role in Z-line assembly.
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Affiliation(s)
- Jie Qi
- Flexcell International Corporation, Hillsborough, North Carolina 27278, USA
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28
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Santiago-Martínez E, Soplop NH, Patel R, Kramer SG. Repulsion by Slit and Roundabout prevents Shotgun/E-cadherin-mediated cell adhesion during Drosophila heart tube lumen formation. J Cell Biol 2008; 182:241-8. [PMID: 18663139 PMCID: PMC2483515 DOI: 10.1083/jcb.200804120] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 06/11/2008] [Indexed: 11/22/2022] Open
Abstract
During Drosophila melanogaster heart development, a lumen forms between apical surfaces of contralateral cardioblasts (CBs). We show that Slit and its receptor Roundabout (Robo) are required at CB apical domains for lumen formation. Mislocalization of Slit outside the apical domain causes ectopic lumen formation and the mislocalization of cell junction proteins, E-cadherin (E-Cad) and Enabled, without disrupting overall CB cell polarity. Ectopic lumen formation is suppressed in robo mutants, which indicates robo's requirement for this process. Genetic evidence suggests that Robo and Shotgun (Shg)/E-Cad function together in modulating CB adhesion. robo and shg/E-Cad transheterozygotes have lumen defects. In robo loss-of-function or shg/E-Cad gain-of-function embryos, lumen formation is blocked because of inappropriate CB adhesion and an accumulation of E-Cad at the apical membrane. In contrast, shg/E-Cad loss-of-function or robo gain-of-function blocks lumen formation due to a loss of CB adhesion. Our data show that Slit and Robo pathways function in lumen formation as a repulsive signal to antagonize E-Cad-mediated cell adhesion.
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Affiliation(s)
- Edgardo Santiago-Martínez
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ 08854, USA
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29
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Epithelial histogenesis during tooth development. Arch Oral Biol 2008; 54 Suppl 1:S25-33. [PMID: 18656852 DOI: 10.1016/j.archoralbio.2008.05.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 05/07/2008] [Accepted: 05/07/2008] [Indexed: 12/31/2022]
Abstract
This paper reviews the current understanding of the progressive changes mediating dental epithelial histogenesis as a basis for future collaborative studies. Tooth development involves morphogenesis, epithelial histogenesis and cell differentiation. The consecutive morphological stages of lamina, bud, cap and bell are also characterized by changes in epithelial histogenesis. Differential cell proliferation rates, apoptosis, and alterations in adhesion and shape lead to the positioning of groups of cells with different functions. During tooth histo-morphogenesis changes occur in basement membrane composition, expression of signalling molecules and the localization of cell surface components. Cell positional identity may be related to cell history. Another important parameter is cell plasticity. Independently of signalling molecules, which play a major role in inducing or modulating specific steps, cell-cell and cell-matrix interactions regulate the plasticity/rigidity of particular domains of the enamel organ. This involves specifying in space the differential growth and influences the progressive tooth morphogenesis by shaping the epithelial-mesenchymal junction. Deposition of a mineralized matrix determines the final shape of the crown. All data reviewed in this paper were investigated in the mouse.
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Koh SWM, Chandrasekara K, Abbondandolo CJ, Coll TJ, Rutzen AR. VIP and VIP gene silencing modulation of differentiation marker N-cadherin and cell shape of corneal endothelium in human corneas ex vivo. Invest Ophthalmol Vis Sci 2008; 49:3491-8. [PMID: 18441300 DOI: 10.1167/iovs.07-1543] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
PURPOSE Vasoactive intestinal peptide (VIP) is expressed by corneal endothelial (CE) cells and is present in the aqueous humor, which bathes CE cells in vivo. This study demonstrated the role of CE cell VIP in maintaining the expression level of a CE differentiation marker, N-cadherin, and the hexagonal cell shape. METHODS To determine the most effective VIP concentration, bovine corneoscleral explants were treated with 0 (control) and 10(-12) to 10(-6) M VIP. Paired human corneas (nine donors) from an eye bank were used as control; the other corneas were treated with VIP. To silence endogenous VIP, paired fresh human donor corneas (from seven cadavers) were transduced with VIP shRNA or the control lentiviral particles and then bisected/quartered for quantitative analysis by semiquantitative RT-PCR (for mRNA) and Western blot analysis/immunocytochemistry (for protein), whereas alizarin red S staining revealed CE cell shape. RESULTS VIP concentration dependently increased bovine CE cell N-cadherin mRNA levels, with the maximal effect observed between 10(-10) (1.47 +/- 0.06-fold; P = 0.002) and 10(-8) M VIP (1.48 +/- 0.18-fold; P = 0.012). VIP (10(-8) M) treatment increased N-cadherin protein levels in bovine and human CE cells to 1.98 +/- 0.28-fold (P = 0.005) and 1.17 +/- 0.10 (range, 0.91-1.87)-fold (P = 0.050) of their respective controls. VIP antagonist (SN)VIPhyb diminished the VIP effect. VIP silencing resulted in deterioration of the hexagonal cell shape and decreased levels of VIP protein and mRNA, N-cadherin (but not connexin-43) mRNA and protein, and the antiapoptotic Bcl-2 protein. CONCLUSIONS Through its autocrine VIP, CE cells play an active role in maintaining the differentiated state and suppressing apoptosis in the corneal endothelium in situ.
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Affiliation(s)
- Shay-Whey M Koh
- Department of Ophthalmology and Visual Sciences, University of Maryland, Baltimore, Maryland 21201, USA.
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31
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Abstract
Cadherin-mediated cell adhesion and signaling is essential for metazoan development and yet is absent from all other multicellular organisms. We found cadherin genes at numbers similar to those observed in complex metazoans in one of the closest single-celled relatives of metazoans, the choanoflagellate Monosiga brevicollis. Because the evolution of metazoans from a single-celled ancestor required novel cell adhesion and signaling mechanisms, the discovery of diverse cadherins in choanoflagellates suggests that cadherins may have contributed to metazoan origins.
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Affiliation(s)
- Monika Abedin
- Department of Molecular and Cell Biology and Center for Integrative Genomics, University of California at Berkeley, Berkeley, CA 94720, USA
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32
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Abstract
In multicellular organisms, cells pack together to form tissues of intricate and well defined morphology. How such cell-packing geometries arise is an important open question in biology, because the functionality of many differentiated tissues depends on their reliable formation. We show that combining adhesive forces due to E- and N-cadherin with a quantitative description of cell membrane elasticity in an interfacial energy model explains not only the qualitative neighbor relations, but also the detailed geometry of a tissue. The characteristic cellular geometries in the eyes of both wild-type Drosophila and genetic mutants are accurately reproduced by using a fixed set of few, physically motivated parameters. The model predicts adhesion strengths in the eye epithelium, quantifies their role relative to membrane elasticity, and reveals how simple minimization of interfacial energy can give rise to complex geometric patterns of important biological functionality.
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Human tropomyosin isoforms in the regulation of cytoskeleton functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 644:201-22. [PMID: 19209824 DOI: 10.1007/978-0-387-85766-4_16] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Over the past two decades, extensive molecular studies have identified multiple tropomyosin isoforms existing in all mammalian cells and tissues. In humans, tropomyosins are encoded by TPM1 (alpha-Tm, 15q22.1), TPM2 (beta-Tm, 9p13.2-p13.1), TPM3 (gamma-Tm, 1q21.2) and TPM4 (delta-Tm, 19p13.1) genes. Through the use of different promoters, alternatively spliced exons and different sites of poly(A) addition signals, at least 22 different tropomyosin cDNAs with full-length open reading frame have been cloned. Compelling evidence suggests that these isoforms play important determinants for actin cytoskeleton functions, such as intracellular vesicle movement, cell migration, cytokinesis, cell proliferation and apoptosis. In vitro biochemical studies and in vivo localization studies suggest that different tropomyosin isoforms have differences in their actin-binding properties and their effects on other actin-binding protein functions and thus, in their specification ofactin microfilaments. In this chapter, we will review what has been learned from experimental studies on human tropomyosin isoforms about the mechanisms for differential localization and functions of tropomyosin. First, we summarize current information concerning human tropomyosin isoforms and relate this to the functions of structural homologues in rodents. We will discuss general strategies for differential localization oftropomyosin isoforms, particularly focusing on differential protein turnover and differential isoform effects on other actin binding protein functions. We will then review tropomyosin functions in regulating cell motility and in modulating the anti-angiogenic activity of cleaved high molecular weight kininogen (HKa) and discuss future directions in this area.
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Abstract
Morphology is an important large-scale manifestation of the global organizational and physiological state of cells, and is commonly used as a qualitative or quantitative measure of the outcome of various assays. Here we evaluate several different basic representations of cell shape - binary masks, distance maps and polygonal outlines - and different subsequent encodings of those representations - Fourier and Zernike decompositions, and the principal and independent components analyses - to determine which are best at capturing biologically important shape variation. We find that principal components analysis of two-dimensional shapes represented as outlines provide measures of morphology which are quantitative, biologically meaningful, human interpretable and work well across a range of cell types and parameter settings.
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Affiliation(s)
- Z Pincus
- Program in Biomedical Informatics, and Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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35
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Cell adhesion and cortex contractility determine cell patterning in the Drosophila retina. Proc Natl Acad Sci U S A 2007; 104:18549-54. [PMID: 18003929 DOI: 10.1073/pnas.0704235104] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Because of the resemblance of many epithelial tissues to densely packed soap bubbles, it has been suggested that surface minimization, which drives soap bubble packing, could be governing cell packing as well. We test this by modeling the shape of the cells in a Drosophila retina ommatidium. We use the observed configurations and shapes in wild-type flies, as well as in flies with different numbers of cells per ommatidia, and mutants with cells where E- or N-cadherin is either deleted or misexpressed. We find that surface minimization is insufficient to model the experimentally observed shapes and packing of the cells based on their cadherin expression. We then consider a model in which adhesion leads to a surface increase, balanced by cell cortex contraction. Using the experimentally observed distributions of E- and N-cadherin, we simulate the packing and cell shapes in the wild-type eye. Furthermore, by changing only the corresponding parameters, this model can describe the mutants with different numbers of cells or changes in cadherin expression.
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Chen J, Hua G, Jurat-Fuentes JL, Abdullah MA, Adang MJ. Synergism of Bacillus thuringiensis toxins by a fragment of a toxin-binding cadherin. Proc Natl Acad Sci U S A 2007; 104:13901-6. [PMID: 17724346 PMCID: PMC1955780 DOI: 10.1073/pnas.0706011104] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The insecticidal crystal proteins produced by Bacillus thuringiensis (Bt) are broadly used to control insect pests with agricultural importance. The cadherin Bt-R(1) is a binding protein for Bt Cry1A toxins in midgut epithelia of tobacco hornworm (Manduca sexta). We previously identified the Bt-R(1) region most proximal to the cell membrane (CR12-MPED) as the essential binding region required for Cry1Ab-mediated cytotoxicity. Here, we report that a peptide containing this region expressed in Escherichia coli functions as a synergist of Cry1A toxicity against lepidopteran larvae. Far-UV circular dichroism and (1)H-NMR spectroscopy confirmed that our purified CR12-MPED peptide mainly consisted of beta-strands and random coils with unfolded structure. CR12-MPED peptide bound brush border membrane vesicles with high affinity (K(d) = 32 nM) and insect midgut microvilli but did not alter Cry1Ab or Cry1Ac binding localization in the midgut. By BIAcore analysis we demonstrate that Cry1Ab binds CR12-MPED at high (9 nM)- and low (1 microM)-affinity sites. CR12-MPED-mediated Cry1A toxicity enhancement was significantly reduced when the high-affinity Cry1A-binding epitope ((1416)GVLTLNIQ(1423)) within the peptide was altered. Because the mixtures of low Bt toxin dose and CR12-MPED peptide effectively control target insect pests, our discovery has important implications related to the use of this peptide to enhance insecticidal activity of Bt toxin-based biopesticides and transgenic Bt crops.
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Affiliation(s)
| | | | | | | | - Michael J. Adang
- Departments of *Entomology and
- Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602-2603
- To whom correspondence should be addressed. E-mail:
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Barco R, Hunt LB, Frump AL, Garcia CB, Benesh A, Caldwell RL, Eid JE. The synovial sarcoma SYT-SSX2 oncogene remodels the cytoskeleton through activation of the ephrin pathway. Mol Biol Cell 2007; 18:4003-12. [PMID: 17686994 PMCID: PMC1995716 DOI: 10.1091/mbc.e07-05-0496] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Synovial sarcoma is a soft tissue cancer associated with a recurrent t(X:18) translocation that generates one of two fusion proteins, SYT-SSX1 or SYT-SSX2. In this study, we demonstrate that SYT-SSX2 is a unique oncogene. Rather than confer enhanced proliferation on its target cells, SYT-SSX2 instead causes a profound alteration of their architecture. This aberrant morphology included elongation of the cell body and formation of neurite-like extensions. We also observed that cells transduced with SYT-SSX2 often repulsed one another. Notably, cell repulsion is a known component of ephrin signaling. Further analysis of SYT-SSX2-infected cells revealed significant increases in the expression and activation of Eph/ephrin pathway components. On blockade of EphB2 signaling SYT-SSX2 infectants demonstrated significant reversion of the aberrant cytoskeletal phenotype. In addition, we discovered, in parallel, that SYT-SSX2 induced stabilization of the microtubule network accompanied by accumulation of detyrosinated Glu tubulin and nocodazole resistance. Glu tubulin regulation was independent of ephrin signaling. The clinical relevance of these studies was confirmed by abundant expression of both EphB2 and Glu tubulin in SYT-SSX2-positive synovial sarcoma tissues. These results indicate that SYT-SSX2 exerts part of its oncogenic effect by altering cytoskeletal architecture in an Eph-dependent manner and cytoskeletal stability through a concurrent and distinct pathway.
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Affiliation(s)
| | | | | | | | | | - Robert L. Caldwell
- Vanderbilt Orthopedic Institute, Vanderbilt University Medical Center, Nashville, TN 37232
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Chintapalli VR, Wang J, Dow JAT. Using FlyAtlas to identify better Drosophila melanogaster models of human disease. Nat Genet 2007; 39:715-20. [PMID: 17534367 DOI: 10.1038/ng2049] [Citation(s) in RCA: 1205] [Impact Index Per Article: 70.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
FlyAtlas, a new online resource, provides the most comprehensive view yet of expression in multiple tissues of Drosophila melanogaster. Meta-analysis of the data shows that a significant fraction of the genome is expressed with great tissue specificity in the adult, demonstrating the need for the functional genomic community to embrace a wide range of functional phenotypes. Well-known developmental genes are often reused in surprising tissues in the adult, suggesting new functions. The homologs of many human genetic disease loci show selective expression in the Drosophila tissues analogous to the affected human tissues, providing a useful filter for potential candidate genes. Additionally, the contributions of each tissue to the whole-fly array signal can be calculated, demonstrating the limitations of whole-organism approaches to functional genomics and allowing modeling of a simple tissue fractionation procedure that should improve detection of weak or tissue-specific signals.
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Yin C, Solnica-Krezel L. Convergence and extension movements affect dynamic notochord-somite interactions essential for zebrafish slow muscle morphogenesis. Dev Dyn 2007; 236:2742-56. [PMID: 17849437 DOI: 10.1002/dvdy.21295] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During vertebrate gastrulation, convergence and extension (C&E) movements shape and position the somites that form the fast and slow muscles. In zebrafish knypek;trilobite non-canonical Wnt mutants, defective C&E movements cause misshapen somites and reduction of slow muscle precursors, the adaxial cells. Here, we demonstrate essential roles of C&E in slow muscle morphogenesis. During segmentation, the adaxial cells change shapes and migrate laterally to form slow muscles at the myotome surface. Using confocal imaging techniques, we show that the adaxial cells undergo three-step shape changes, including dorsoventral elongation, anterior-ward rotation, and anteroposterior elongation. The adaxial cells in knypek;trilobite double mutants maintain prolonged contact with the notochord and fail to rotate anteriorly. Such a defect was suppressed by physical removal of their notochord or by introducing wild-type notochord cells into the mutant. We propose that in the double mutants, impaired C&E movements disrupt notochord development, which impedes the adaxial cell shape changes.
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Affiliation(s)
- Chunyue Yin
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, USA
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40
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Lanzardo S, Curcio C, Forni G, Antón IM. A role for WASP Interacting Protein, WIP, in fibroblast adhesion, spreading and migration. Int J Biochem Cell Biol 2006; 39:262-74. [PMID: 17008118 DOI: 10.1016/j.biocel.2006.08.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 08/10/2006] [Accepted: 08/12/2006] [Indexed: 01/21/2023]
Abstract
The WASP (Wiskott Aldrich Syndrome Protein) Interacting Protein, WIP, regulates actin polymerization and the formation of actin-rich structures such as filopodia and lamellipodia, each of which is involved in cellular adhesion, spreading and migration. To define the role for WIP in these activities, we analysed cell adhesion and spreading as well as the redistribution of polymerised actin and paxillin that occurred when fibroblasts were plated onto different substrata. We compared the effect of WIP overexpression (gain of function) with that of WIP deficiency (loss of function) on these parameters. WIP-overexpression delayed cellular adhesion and spreading, an effect that could be compensated for by exposure to Y-27632, a well characterized ROCK (Rho kinase) inhibitor. WIP overexpression augmented the phosphorylation of Erk and JNK induced by binding to fibronectin, suggesting that WIP participates in signal transduction pathways initiated by integrin engagement. Conversely, WIP deficiency accelerated fibroblast adhesion to plastic and led to the formation of enlarged focal adhesions. The influence of WIP on fibroblast migration was measured by scratch assay. WIP-overexpression reduced migration while WIP-deficiency increased it, suggesting that WIP acts as a negative regulator of fibroblast migration. Together, these findings suggest a novel role for WIP in fibroblast adhesion, spreading and migration.
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Cela C, Llimargas M. Egfr is essential for maintaining epithelial integrity during tracheal remodelling in Drosophila. Development 2006; 133:3115-25. [PMID: 16831830 DOI: 10.1242/dev.02482] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A fundamental requirement during organogenesis is to preserve tissue integrity to render a mature and functional structure. Many epithelial organs, such as the branched tubular structures, undergo a tremendous process of tissue remodelling to attain their final pattern. The cohesive properties of these tissues need to be finely regulated to promote adhesion yet allow flexibility during extensive tissue remodelling. Here, we report a new role for the Egfr pathway in maintaining epithelial integrity during tracheal development in Drosophila. We show that the integrity-promoting Egfr function is transduced by the ERK-type MAPK pathway, but does not require the downstream transcription factor Pointed. Compromising Egfr signalling, by downregulating different elements of the pathway or by overexpressing the Mkp3 negative regulator, leads to loss of tube integrity, whereas upregulation of the pathway results in increased tissue stiffness. We find that regulation of MAPK pathway activity by Breathless signalling does not impinge on tissue integrity. Egfr effects on tissue integrity correlate with differences in the accumulation of markers for cadherin-based cell-cell adhesion. Accordingly, downregulation of cadherin-based cell-cell adhesion gives rise to tracheal integrity defects. Our results suggest that the Egfr pathway regulates maintenance of tissue integrity, at least in part, through the modulation of cell adhesion. This finding establishes a link between a developmental pathway governing tracheal formation and cell adhesiveness.
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Affiliation(s)
- Carolina Cela
- Institut de Biologia Molecular de Barcelona (IBMB Samitier 1-5, 08028 Barcelona, Spain
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Stubbs JL, Davidson L, Keller R, Kintner C. Radial intercalation of ciliated cells during Xenopus skin development. Development 2006; 133:2507-15. [PMID: 16728476 DOI: 10.1242/dev.02417] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cells with motile cilia cover the skin of Xenopus tadpoles in a characteristic spacing pattern. This pattern arises during early development when cells within the inner layer of ectoderm are selected out by Notch to form ciliated cell precursors (CCPs) that then radially intercalate into the outer epithelial cell layer to form ciliated cells. When Notch is inhibited and CCPs are overproduced, radial intercalation becomes limiting and the spacing of ciliated cells is maintained. To determine why this is the case, we used confocal microscopy to image intercalating cells labeled using transplantation and a transgenic approach that labels CCPs with green fluorescent protein (GFP). Our results indicate that inner cells intercalate by first wedging between the basal surface of the outer epithelium but only insert apically at the vertices where multiple outer cells make contact. When overproduced, more CCPs are able to wedge basally, but apical insertion becomes limiting. We propose that limitations imposed by the outer layer, along with restrictions on the apical insertion of CCPs, determine their pattern of radial intercalation.
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Affiliation(s)
- Jennifer L Stubbs
- Salk Institute for Biological Studies, Molecular Neurobiology Laboratory, La Jolla, CA 92037, USA
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Rashid D, Newell K, Shama L, Bradley R. A requirement for NF-protocadherin and TAF1/Set in cell adhesion and neural tube formation. Dev Biol 2006; 291:170-81. [PMID: 16426602 DOI: 10.1016/j.ydbio.2005.12.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2005] [Revised: 12/01/2005] [Accepted: 12/12/2005] [Indexed: 01/22/2023]
Abstract
Neurulation in vertebrates is an intricate process requiring extensive alterations in cell contacts and cellular morphologies as the cells in the neural ectoderm shape and form the neural folds and neural tube. Despite these complex interactions, little is known concerning the molecules that mediate cell adhesion within the embryonic neural plate and neural folds. Here, we demonstrate the requirement for NF-protocadherin (NFPC) and its cytosolic partner TAF1/Set for proper neurulation in Xenopus. Both NFPC and TAF1 function in cell-cell adhesion in the neural ectoderm, and disruptions in either NFPC or TAF1 result in a failure of the neural tube to close. This neural tube defect can be attributed to a lack of proper organization of the cells in the dorsal neural folds, manifested by a loss in the columnar epithelial morphology and apical localization of F-actin. However, the epidermal ectoderm is still able to migrate and cover the open neural tube, indicating that the fusions of the neural tube and epidermis are separate events. These studies demonstrate that NFPC and TAF1 function to maintain proper cell-cell interactions within the neural folds and suggest that NFPC and TAF1 participate in novel adhesive mechanisms that contribute to the final events of vertebrate neurulation.
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Affiliation(s)
- Dana Rashid
- Department of Cell Biology and Neuroscience, Montana State University, Bozeman, MT 59717, USA
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Major RJ, Irvine KD. Localization and requirement for Myosin II at the dorsal-ventral compartment boundary of theDrosophila wing. Dev Dyn 2006; 235:3051-8. [PMID: 17013876 DOI: 10.1002/dvdy.20966] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
As organisms develop, their tissues can become separated into distinct cell populations through the establishment of compartment boundaries. Compartment boundaries have been discovered in a wide variety of tissues, but in many cases the molecular mechanisms that separate cells remain poorly understood. In the Drosophila wing, a stripe of Notch activation maintains the dorsal-ventral compartment boundary, through a process that depends on the actin cytoskeleton. Here, we show that the dorsal-ventral boundary exhibits a distinct accumulation of Myosin II, and that this accumulation is regulated downstream of Notch signaling. Conversely, the dorsal-ventral boundary is depleted for the Par-3 homologue Bazooka. We further show that mutations in the Myosin heavy chain subunit encoded by zipper can impair dorsal-ventral compartmentalization without affecting anterior-posterior compartmentalization. These observations identify a distinct accumulation and requirement for Myosin activity in dorsal-ventral compartmentalization, and suggest a novel mechanism in which contractile tension along an F-actin cable at the compartment boundary contributes to compartmentalization.
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Affiliation(s)
- Robert J Major
- Howard Hughes Medical Institute, Waksman Institute, and Department of Molecular Biology and Biochemistry, Rutgers The State University of New Jersey, Piscataway, New Jersey, USA
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Yoder M, Hildebrand JD. Shroom4 (Kiaa1202) is an actin-associated protein implicated in cytoskeletal organization. ACTA ACUST UNITED AC 2006; 64:49-63. [PMID: 17009331 DOI: 10.1002/cm.20167] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
All animal cells utilize a specialized set of cytoskeletal proteins to determine their overall shape and the organization of their intracellular compartments and organelles. During embryonic development, the dynamic nature of the actin cytoskeleton is critical for virtually all morphogenic events requiring changes in cell shape, migration, adhesion, and division. The behavior of the actin cytoskeleton is modulated by a myriad of accessory proteins. Shroom3 is an actin binding protein that regulates neural tube morphogenesis by eliciting changes in cell shape through a myosin II-dependent pathway. The Shroom-related gene SHROOM4 (formerly called KIAA1202) has also been implicated in neural development, as mutations in this gene are associated with human X-linked mental retardation. To better understand the function of Shrm4 in embryonic development, we have cloned mouse Shroom4 and characterized its protein product in vivo and in vitro. Shroom4 is expressed in a wide range of cell types during mouse development, including vascular endothelium and the polarized epithelium of the neural tube and kidney. In endothelial cells and embryo fibroblasts, endogenous Shroom4 co-distributes with myosin II to a distinct cytoplasmic population of F-actin and ectopic expression of Shroom4 in multiple cell types enhances or induces the formation of this actin-based structure. This localization is mediated, at least in part, by the direct interaction of Shroom4 and F-actin. Our results suggest that Shroom4 is a regulator of cytoskeletal architecture that may play an important role in vertebrate development.
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Affiliation(s)
- Michael Yoder
- Department of Biological Sciences, University of Pittsburgh, 4249 Fifth Avenue, Pittsburgh, PA 15260, USA
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