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Kasper JY, Laschke MW, Koch M, Alibardi L, Magin T, Niessen CM, del Campo A. Actin-templated Structures: Nature's Way to Hierarchical Surface Patterns (Gecko's Setae as Case Study). ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2303816. [PMID: 38145336 PMCID: PMC10933612 DOI: 10.1002/advs.202303816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 11/10/2023] [Indexed: 12/26/2023]
Abstract
The hierarchical design of the toe pad surface in geckos and its reversible adhesiveness have inspired material scientists for many years. Micro- and nano-patterned surfaces with impressive adhesive performance have been developed to mimic gecko's properties. While the adhesive performance achieved in some examples has surpassed living counterparts, the durability of the fabricated surfaces is limited and the capability to self-renew and restore function-inherent to biological systems-is unimaginable. Here the morphogenesis of gecko setae using skin samples from the Bibron´s gecko (Chondrodactylus bibronii) is studied. Gecko setae develop as specialized apical differentiation structures at a distinct cell-cell layer interface within the skin epidermis. A primary role for F-actin and microtubules as templating structural elements is necessary for the development of setae's hierarchical morphology, and a stabilization role of keratins and corneus beta proteins is identified. Setae grow from single cells in a bottom layer protruding into four neighboring cells in the upper layer. The resulting multicellular junction can play a role during shedding by facilitating fracture of the cell-cell interface and release of the high aspect ratio setae. The results contribute to the understanding of setae regeneration and may inspire future concepts to bioengineer self-renewable patterned adhesive surfaces.
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Affiliation(s)
- Jennifer Y. Kasper
- INM‐Leibniz Institute for New MaterialsCampus D2 266123SaarbrueckenGermany
| | - Matthias W. Laschke
- Institute for Clinical and Experimental SurgerySaarland University66421HomburgGermany
| | - Marcus Koch
- INM‐Leibniz Institute for New MaterialsCampus D2 266123SaarbrueckenGermany
| | - Lorenzo Alibardi
- Comparative AnatomyDepartment of BiologyUniversity of Bologna& Comparative Histolab40126BolognaItaly
| | - Thomas Magin
- Division of Cell and Developmental BiologyInstitute of BiologyLeipzig University04103LeipzigGermany
| | - Carien M. Niessen
- Department Cell Biology of the SkinCologne Excellence Cluster for Stress Responses in Ageing‐associated diseases (CECAD)Center for Molecular Medicine Cologne (CMMC)University Hospital CologneUniversity of Cologne50931CologneGermany
| | - Aránzazu del Campo
- INM‐Leibniz Institute for New MaterialsCampus D2 266123SaarbrueckenGermany
- Chemistry DepartmentSaarland University66123SaarbrueckenGermany
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2
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Mallart C, Netter S, Chalvet F, Claret S, Guichet A, Montagne J, Pret AM, Malartre M. JAK-STAT-dependent contact between follicle cells and the oocyte controls Drosophila anterior-posterior polarity and germline development. Nat Commun 2024; 15:1627. [PMID: 38388656 PMCID: PMC10883949 DOI: 10.1038/s41467-024-45963-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 02/08/2024] [Indexed: 02/24/2024] Open
Abstract
The number of embryonic primordial germ cells in Drosophila is determined by the quantity of germ plasm, whose assembly starts in the posterior region of the oocyte during oogenesis. Here, we report that extending JAK-STAT activity in the posterior somatic follicular epithelium leads to an excess of primordial germ cells in the future embryo. We show that JAK-STAT signaling is necessary for the differentiation of approximately 20 specialized follicle cells maintaining tight contact with the oocyte. These cells define, in the underlying posterior oocyte cortex, the anchoring of the germ cell determinant oskar mRNA. We reveal that the apical surface of these posterior anchoring cells extends long filopodia penetrating the oocyte. We identify two JAK-STAT targets in these cells that are each sufficient to extend the zone of contact with the oocyte, thereby leading to production of extra primordial germ cells. JAK-STAT signaling thus determines a fixed number of posterior anchoring cells required for anterior-posterior oocyte polarity and for the development of the future germline.
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Affiliation(s)
- Charlotte Mallart
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sophie Netter
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université de Versailles-Saint-Quentin en Yvelines, Université Paris-Saclay, Gif- sur-Yvette, France
| | - Fabienne Chalvet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sandra Claret
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Antoine Guichet
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Jacques Montagne
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Anne-Marie Pret
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université de Versailles-Saint-Quentin en Yvelines, Université Paris-Saclay, Gif- sur-Yvette, France
| | - Marianne Malartre
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France.
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3
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Czukiewska SM, Fan X, Mulder AA, Van Der Helm T, Hillenius S, Van Der Meeren L, Matorras R, Eguizabal C, Lei L, Koning RI, Chuva De Sousa Lopes SM. Cell-cell interactions during the formation of primordial follicles in humans. Life Sci Alliance 2023; 6:e202301926. [PMID: 37643865 PMCID: PMC10465921 DOI: 10.26508/lsa.202301926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 08/19/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023] Open
Abstract
Gametogenesis is a complex and sex-specific multistep process during which the gonadal somatic niche plays an essential regulatory role. One of the most crucial steps during human female gametogenesis is the formation of primordial follicles, the functional unit of the ovary that constitutes the pool of follicles available at birth during the entire reproductive life. However, the relation between human fetal germ cells (hFGCs) and gonadal somatic cells during the formation of the primordial follicles remains largely unexplored. We have discovered that hFGCs can form multinucleated syncytia, some connected via interconnecting intercellular bridges, and that not all nuclei in hFGC-syncytia were synchronous regarding meiotic stage. As hFGCs progressed in development, pre-granulosa cells formed protrusions that seemed to progressively constrict individual hFGCs, perhaps contributing to separate them from the multinucleated syncytia. Our findings highlighted the cell-cell interaction and molecular dynamics between hFGCs and (pre)granulosa cells during the formation of primordial follicles in humans. Knowledge on how the pool of primordial follicle is formed is important to understand human infertility.
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Affiliation(s)
- Sylwia M Czukiewska
- https://ror.org/05xvt9f17 Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, Netherlands
| | - Xueying Fan
- https://ror.org/05xvt9f17 Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, Netherlands
| | - Adriaan A Mulder
- https://ror.org/05xvt9f17 Electron Microscopy Facility, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Talia Van Der Helm
- https://ror.org/05xvt9f17 Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, Netherlands
| | - Sanne Hillenius
- https://ror.org/05xvt9f17 Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, Netherlands
| | - Lotte Van Der Meeren
- https://ror.org/05xvt9f17 Department of Pathology, Leiden University Medical Center, Leiden, Netherlands
- Department of Pathology, Erasmus Medical Center, Rotterdam, Netherlands
| | - Roberto Matorras
- IVIRMA, IVI Bilbao, Bilbao, Spain
- Human Reproduction Unit, Cruces University Hospital, Bilbao, Spain
- Department of Obstetrics and Gynecology, Basque Country University, Bilbao, Spain
- Biocruces Bizkaia Health Research Institute, Bilbao, Spain
| | - Cristina Eguizabal
- Cell Therapy, Stem Cells and Tissues Group, Basque Centre for Blood Transfusion and Human Tissues, Galdakao, Spain
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
| | - Lei Lei
- Department of Obstetrics, Gynecology and Women's Health, University of Missouri School of Medicine, Columbia, MO, USA
| | - Roman I Koning
- https://ror.org/05xvt9f17 Electron Microscopy Facility, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands
| | - Susana M Chuva De Sousa Lopes
- https://ror.org/05xvt9f17 Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, Netherlands
- https://ror.org/00xmkp704 Department for Reproductive Medicine, Ghent University Hospital, Ghent, Belgium
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4
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Zhang N, Häring M, Wolf F, Großhans J, Kong D. Dynamics and functions of E-cadherin complexes in epithelial cell and tissue morphogenesis. MARINE LIFE SCIENCE & TECHNOLOGY 2023; 5:585-601. [PMID: 38045551 PMCID: PMC10689684 DOI: 10.1007/s42995-023-00206-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 10/31/2023] [Indexed: 12/05/2023]
Abstract
Cell-cell adhesion is at the center of structure and dynamics of epithelial tissue. E-cadherin-catenin complexes mediate Ca2+-dependent trans-homodimerization and constitute the kernel of adherens junctions. Beyond the basic function of cell-cell adhesion, recent progress sheds light the dynamics and interwind interactions of individual E-cadherin-catenin complex with E-cadherin superclusters, contractile actomyosin and mechanics of the cortex and adhesion. The nanoscale architecture of E-cadherin complexes together with cis-interactions and interactions with cortical actomyosin adjust to junctional tension and mechano-transduction by reinforcement or weakening of specific features of the interactions. Although post-translational modifications such as phosphorylation and glycosylation have been implicated, their role for specific aspects of in E-cadherin function has remained unclear. Here, we provide an overview of the E-cadherin complex in epithelial cell and tissue morphogenesis focusing on nanoscale architectures by super-resolution approaches and post-translational modifications from recent, in particular in vivo, studies. Furthermore, we review the computational modelling in E-cadherin complexes and highlight how computational modelling has contributed to a deeper understanding of the E-cadherin complexes.
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Affiliation(s)
- Na Zhang
- Department of Biology, Philipps University, 35043 Marburg, Germany
| | - Matthias Häring
- Göttingen Campus Institute for Dynamics of Biological Networks (CIDBN), Georg August University Göttingen, 37073 Göttingen, Germany
| | - Fred Wolf
- Göttingen Campus Institute for Dynamics of Biological Networks (CIDBN), Georg August University Göttingen, 37073 Göttingen, Germany
| | - Jörg Großhans
- Department of Biology, Philipps University, 35043 Marburg, Germany
- Göttingen Campus Institute for Dynamics of Biological Networks (CIDBN), Georg August University Göttingen, 37073 Göttingen, Germany
| | - Deqing Kong
- Department of Biology, Philipps University, 35043 Marburg, Germany
- Göttingen Campus Institute for Dynamics of Biological Networks (CIDBN), Georg August University Göttingen, 37073 Göttingen, Germany
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5
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Bax NA, Wang A, Huang DL, Pokutta S, Weis WI, Dunn AR. Multi-level Force-dependent Allosteric Enhancement of αE-catenin Binding to F-actin by Vinculin. J Mol Biol 2023; 435:167969. [PMID: 36682678 PMCID: PMC9957948 DOI: 10.1016/j.jmb.2023.167969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 01/10/2023] [Accepted: 01/11/2023] [Indexed: 01/22/2023]
Abstract
Classical cadherins are transmembrane proteins whose extracellular domains link neighboring cells, and whose intracellular domains connect to the actin cytoskeleton via β-catenin and α-catenin. The cadherin-catenin complex transmits forces that drive tissue morphogenesis and wound healing. In addition, tension-dependent changes in αE-catenin conformation enables it to recruit the actin-binding protein vinculin to cell-cell junctions, which contributes to junctional strengthening. How and whether multiple cadherin-complexes cooperate to reinforce cell-cell junctions in response to load remains poorly understood. Here, we used single-molecule optical trap measurements to examine how multiple cadherin-catenin complexes interact with F-actin under load, and how this interaction is influenced by the presence of vinculin. We show that force oriented toward the (-) end of the actin filament results in mean lifetimes 3-fold longer than when force was applied towards the barbed (+) end. We also measured force-dependent actin binding by a quaternary complex comprising the cadherin-catenin complex and the vinculin head region, which cannot itself bind actin. Binding lifetimes of this quaternary complex increased as additional complexes bound F-actin, but only when load was oriented toward the (-) end. In contrast, the cadherin-catenin complex alone did not show this form of cooperativity. These findings reveal multi-level, force-dependent regulation that enhances the strength of the association of multiple cadherin/catenin complexes with F-actin, conferring positive feedback that may strengthen the junction and polarize F-actin to facilitate the emergence of higher-order cytoskeletal organization.
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Affiliation(s)
- Nicolas A Bax
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, United States. https://twitter.com/@bax1337
| | - Amy Wang
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, United States; Department of Chemical Engineering, Stanford University School of Engineering, United States. https://twitter.com/@amywang01
| | - Derek L Huang
- Graduate Program in Biophysics, Stanford University, United States
| | - Sabine Pokutta
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, United States
| | - William I Weis
- Departments of Structural Biology and Molecular & Cellular Physiology, Stanford University School of Medicine, United States.
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University School of Engineering, United States; Stanford Cardiovascular Institute, Stanford School of Medicine.
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TRIM40 is a pathogenic driver of inflammatory bowel disease subverting intestinal barrier integrity. Nat Commun 2023; 14:700. [PMID: 36755029 PMCID: PMC9908899 DOI: 10.1038/s41467-023-36424-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 01/30/2023] [Indexed: 02/10/2023] Open
Abstract
The cortical actin cytoskeleton plays a critical role in maintaining intestinal epithelial integrity, and the loss of this architecture leads to chronic inflammation, as seen in inflammatory bowel disease (IBD). However, the exact mechanisms underlying aberrant actin remodeling in pathological states remain largely unknown. Here, we show that a subset of patients with IBD exhibits substantially higher levels of tripartite motif-containing protein 40 (TRIM40), a gene that is hardly detectable in healthy individuals. TRIM40 is an E3 ligase that directly targets Rho-associated coiled-coil-containing protein kinase 1 (ROCK1), an essential kinase involved in promoting cell-cell junctions, markedly decreasing the phosphorylation of key signaling factors critical for cortical actin formation and stabilization. This causes failure of the epithelial barrier function, thereby promoting a long-lived inflammatory response. A mutant TRIM40 lacking the RING, B-box, or C-terminal domains has impaired ability to accelerate ROCK1 degradation-driven cortical actin disruption. Accordingly, Trim40-deficient male mice are highly resistant to dextran sulfate sodium (DSS)-induced colitis. Our findings highlight that aberrant upregulation of TRIM40, which is epigenetically silenced under healthy conditions, drives IBD by subverting cortical actin formation and exacerbating epithelial barrier dysfunction.
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7
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EVL Promotes Osteo-/Odontogenic Differentiation of Dental Pulp Stem Cells via Activating JNK Signaling Pathway. Stem Cells Int 2023; 2023:7585111. [PMID: 36684389 PMCID: PMC9851786 DOI: 10.1155/2023/7585111] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 12/06/2022] [Accepted: 12/20/2022] [Indexed: 01/14/2023] Open
Abstract
Objective Human dental pulp stem cells (hDPSCs) were recognized as a suitable and promising source of stem cells in dental pulp regeneration. However, the mechanism by which hDPSCs differentiation into osteo-/odontogenic lineage remains unclear. Ena/VASP-like protein (EVL) has been found to be involved in diverse biological processes. In this study, we explored the role and underlying mechanism of EVL in osteo-/odontogenic differentiation of hDPSCs. Methods Expression of EVL was detected in hDPSCs by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot (WB) analyses during osteo-/odontogenic differentiation. The function of EVL in osteo-/odontogenic differentiation and involvement of MAPK signaling pathways were evaluated by alkaline phosphatase (ALP) staining and activity, alizarin red staining (ARS), and qRT-PCR and western blot analyses. Results The expression of EVL was upregulated during osteo-/odontogenic differentiation of hDPSCs. Overexpression of EVL significantly increased osteo-/odontogenic capacity of hDPSCs, which was reflected in increased alkaline phosphatase (ALP) staining, ALP activity, mineralized nodule formation, and the expressions of genes related to osteo-/odontogenic differentiation, while downregulation of EVL inhibited it. In addition, EVL activated the JNK pathway and phosphorylation of p38 MAPK during differentiation procedure of hDPSCs. The EVL-enhanced differentiation of DPSCs was suppressed by blocking the JNK pathway, rather than the p38 MAPK pathway. Conclusion EVL promotes the osteo-/odontogenic differentiation of hDPSCs by activating the JNK pathway, providing a future target for osteo-/odontogenic differentiation and dental pulp regeneration.
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8
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Williams AM, Donoughe S, Munro E, Horne-Badovinac S. Fat2 polarizes the WAVE complex in trans to align cell protrusions for collective migration. eLife 2022; 11:e78343. [PMID: 36154691 PMCID: PMC9576270 DOI: 10.7554/elife.78343] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 09/11/2022] [Indexed: 11/13/2022] Open
Abstract
For a group of cells to migrate together, each cell must couple the polarity of its migratory machinery with that of the other cells in the cohort. Although collective cell migrations are common in animal development, little is known about how protrusions are coherently polarized among groups of migrating epithelial cells. We address this problem in the collective migration of the follicular epithelial cells in Drosophila melanogaster. In this epithelium, the cadherin Fat2 localizes to the trailing edge of each cell and promotes the formation of F-actin-rich protrusions at the leading edge of the cell behind. We show that Fat2 performs this function by acting in trans to concentrate the activity of the WASP family verprolin homolog regulatory complex (WAVE complex) at one long-lived region along each cell's leading edge. Without Fat2, the WAVE complex distribution expands around the cell perimeter and fluctuates over time, and protrusive activity is reduced and unpolarized. We further show that Fat2's influence is very local, with sub-micron-scale puncta of Fat2 enriching the WAVE complex in corresponding puncta just across the leading-trailing cell-cell interface. These findings demonstrate that a trans interaction between Fat2 and the WAVE complex creates stable regions of protrusive activity in each cell and aligns the cells' protrusions across the epithelium for directionally persistent collective migration.
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Affiliation(s)
- Audrey Miller Williams
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Seth Donoughe
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
| | - Edwin Munro
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
- Committee on Development, Regeneration, and Stem Cell Biology, University of ChicagoChicagoUnited States
- Institute for Biophysical Dynamics, University of ChicagoChicagoUnited States
| | - Sally Horne-Badovinac
- Department of Molecular Genetics and Cell Biology, University of ChicagoChicagoUnited States
- Committee on Development, Regeneration, and Stem Cell Biology, University of ChicagoChicagoUnited States
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Fernandez-Gonzalez R, Peifer M. Powering morphogenesis: multiscale challenges at the interface of cell adhesion and the cytoskeleton. Mol Biol Cell 2022; 33. [PMID: 35696393 DOI: 10.1091/mbc.e21-09-0452] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Among the defining features of the animal kingdom is the ability of cells to change shape and move. This underlies embryonic and postembryonic development, tissue homeostasis, regeneration, and wound healing. Cell shape change and motility require linkage of the cell's force-generating machinery to the plasma membrane at cell-cell and cell-extracellular matrix junctions. Connections of the actomyosin cytoskeleton to cell-cell adherens junctions need to be both resilient and dynamic, preventing tissue disruption during the dramatic events of embryonic morphogenesis. In the past decade, new insights radically altered the earlier simple paradigm that suggested simple linear linkage via the cadherin-catenin complex as the molecular mechanism of junction-cytoskeleton interaction. In this Perspective we provide a brief overview of our current state of knowledge and then focus on selected examples highlighting what we view as the major unanswered questions in our field and the approaches that offer exciting new insights at multiple scales from atomic structure to tissue mechanics.
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Affiliation(s)
- Rodrigo Fernandez-Gonzalez
- Institute of Biomedical Engineering, University of Toronto, Toronto, ON M5S 3G5, Canada.,Translational Biology and Engineering Program, Ted Rogers Centre for Heart Research, University of Toronto, Toronto, ON M5S 3G5, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.,Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Mark Peifer
- Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599-3280.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3280
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10
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Hunt EL, Rai H, Harris TJC. SCAR/WAVE complex recruitment to a supracellular actomyosin cable by myosin activators and a junctional Arf-GEF during Drosophila dorsal closure. Mol Biol Cell 2022; 33. [DOI: 10.1091/mbc.e22-03-0107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Expansive Arp2/3 actin networks and contractile actomyosin networks can be spatially and temporally segregated within the cell, but the networks also interact closely at various sites, including adherens junctions. However, molecular mechanisms coordinating these interactions remain unclear. We found that the SCAR/WAVE complex, an Arp2/3 activator, is enriched at adherens junctions of the leading edge actomyosin cable during Drosophila dorsal closure. Myosin activators were both necessary and sufficient for SCAR/WAVE accumulation at leading edge junctions. The same myosin activators were previously shown to recruit the cytohesin Arf-GEF Steppke to these sites, and mammalian studies have linked Arf small G protein signaling to SCAR/WAVE activation. During dorsal closure, we find that Steppke is required for SCAR/WAVE enrichment at the actomyosin-linked junctions. Arp2/3 also localizes to adherens junctions of the leading edge cable. We propose that junctional actomyosin activity acts through Steppke to recruit SCAR/WAVE and Arp2/3 for regulation of the leading edge supracellular actomyosin cable during dorsal closure.
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Affiliation(s)
- Erin L. Hunt
- Department of Cell & Systems Biology, University of Toronto
| | - Hrishika Rai
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata
- International Visiting Graduate Students Study Abroad Program, University of Toronto
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Kasioulis I, Dady A, James J, Prescott A, Halley PA, Storey KG. A lateral protrusion latticework connects neuroepithelial cells and is regulated during neurogenesis. J Cell Sci 2022; 135:274540. [PMID: 35217862 PMCID: PMC8995095 DOI: 10.1242/jcs.259897] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
Dynamic contacts between cells within the developing neuroepithelium are poorly understood but play important roles in cell and tissue morphology and cell signalling. Here, using live-cell imaging and electron microscopy we reveal multiple protrusive structures in neuroepithelial apical endfeet of the chick embryonic spinal cord, including sub-apical protrusions that extend laterally within the tissue, and observe similar structures in human neuroepithelium. We characterise the dynamics, shape and cytoskeleton of these lateral protrusions and distinguish them from cytonemes, filopodia and tunnelling nanotubes. We demonstrate that lateral protrusions form a latticework of membrane contacts between non-adjacent cells, depend on actin but not microtubule dynamics, and provide a lamellipodial-like platform for further extending fine actin-dependent filipodia. We find that lateral protrusions depend on the actin-binding protein WAVE1 (also known as WASF1): misexpression of mutant WAVE1 attenuated protrusion and generated a round-ended apical endfoot morphology. However, this did not alter apico-basal cell polarity or tissue integrity. During normal neuronal delamination, lateral protrusions were withdrawn, but precocious protrusion loss induced by mutant WAVE1 was insufficient to trigger neurogenesis. This study uncovers a new form of cell-cell contact within the developing neuroepithelium, regulation of which prefigures neuronal delamination. This article has an associated First Person interview with the first author of the paper.
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