Myosin II isoforms play distinct roles in adherens junction biogenesis
Melina L. Heuze,
Gautham Hari Narayana Sankara Narayana,
Joseph D 'Alessandro,
Victor Cellerin,
Tien Dang,
David S. Williams,
Jan C. M. Van Hest,
Philippe Marcq,
Rene-Marc Mege, et al.
Adherens junction (AJ) assembly under force is essential for many biological processes like epithelial monolayer bending, collective cell migration, cell extrusion and wound healing. The acto-myosin cytoskeleton acts as a major force-generator during the de novo formation and remodeling of AJ. Here, we investigated the role of non-muscle myosin II isoforms (NMIIA and NMIIB) in epithelial junction assembly. NMIIA and NMIIB differentially regulate biogenesis of AJ through association with distinct actin networks. Analysis of junction dynamics, actin organization, and mechanical forces of control and knockdown cells for myosins revealed that NMIIA provides the mechanical tugging force necessary for cell-cell junction reinforcement and maintenance. NMIIB is involved in E-cadherin clustering, maintenance of a branched actin layer connecting E-cadherin complexes and perijunctional actin fibres leading to the building-up of anisotropic stress. These data reveal unanticipated complementary functions of NMIIA and NMIIB in the biogenesis and integrity of AJ.
Sustained Oscillations of Epithelial Cell Sheets
Gregoire Peyret,
Romain Mueller,
Joseph d'Alessandro,
Simon Begnaud,
Philippe Marcq,
Rene-Marc Mege,
Julia M. Yeomans,
Amin Doostmohammadi,
Benoit Ladoux
Biophysical Journal
117
(3)
464-478
(2019)
| Journal
| PDF
Morphological changes during development, tissue repair, and disease largely rely on coordinated cell movements and are controlled by the tissue environment. Epithelial cell sheets are often subjected to large-scale deformation during tissue formation. The active mechanical environment in which epithelial cells operate have the ability to promote collective oscillations, but how these cellular movements are generated and relate to collective migration remains unclear. Here, combining in vitro experiments and computational modeling, we describe a form of collective oscillations in confined epithelial tissues in which the oscillatory motion is the dominant contribution to the cellular movements. We show that epithelial cells exhibit large-scale coherent oscillations when constrained within micropatterns of varying shapes and sizes and that their period and amplitude are set by the smallest confinement dimension. Using molecular perturbations, we then demonstrate that force transmission at cell-cell junctions and its coupling to cell polarity are pivotal for the generation of these collective movements. We find that the resulting tissue deformations are sufficient to trigger osillatory mechanotransduction of YAP within cells, potentially affecting a wide range of cellular processes.
Reciprocal regulation of actomyosin organization and contractility in nonmuscle cells by tropomyosins and alpha-actinins
Shiqiong Hu,
Hanna Grobe,
Zhenhuan Guo,
Yu-Hsiu Wang,
Bryant L. Doss,
Meng Pan,
Benoit Ladoux,
Alexander D. Bershadsky,
Ronen Zaidel-Bar
Molecular Biology of the Cell
30
(16)
2025-2036
(2019)
| Journal
Contractile arrays of actin and myosin II filaments drive many essential processes in nonmuscle cells, including migration and adhesion. Sequential organization of actin and myosin along one dimension is followed by expansion into a two-dimensional network of parallel actomyosin fibers, in which myosin filaments are aligned to form stacks. The process of stack formation has been studied in detail. However, factors that oppose myosin stack formation have not yet been described. Here, we show that tropomyosins act as negative regulators of myosin stack formation. Knockdown of any or all tropomyosin isoforms in rat embryonic fibroblasts resulted in longer and more numerous myosin stacks and a highly ordered actomyosin organization. The molecular basis for this, we found, is the competition between tropomyosin and alpha-actinin for binding actin. Surprisingly, excessive order in the actomyosin network resulted in smaller focal adhesions, lower tension within the network, and smaller traction forces. Conversely, disordered actomyosin bundles induced by alpha-actinin knockdown led to higher than normal tension and traction forces. Thus, tropomyosin acts as a check on alpha-actinin to achieve intermediate levels of myosin stacks matching the force requirements of the cell.
Enhanced cell-cell contact stability and decreased N-cadherin-mediated migration upon fibroblast growth factor receptor-N-cadherin cross talk
Nguyen Thao,
Laurence Duchesne,
Gautham Hari Narayana Sankara Narayana,
Nicole Boggetto,
David D. Fernig,
Chandrashekhar Uttamrao Murade,
Benoit Ladoux,
Rene-Marc Mege
N-cadherin adhesion has been reported to enhance cancer and neuronal cell migration either by mediating actomyosin-based force transduction or initiating fibroblast growth factor receptor (FGFR)-dependent biochemical signalling. Here we show that FGFR1 reduces N-cadherin-mediated cell migration. Both proteins are co-stabilised at cell-cell contacts through direct interaction. As a consequence, cell adhesion is strengthened, limiting the migration of cells on N-cadherin. Both the inhibition of migration and the stabilisation of cell adhesions require the FGFR activity stimulated by N-cadherin engagement. FGFR1 stabilises N-cadherin at the cell membrane through a pathway involving Src and p120. Moreover, FGFR1 stimulates the anchoring of N-cadherin to actin. We found that the migratory behaviour of cells depends on an optimum balance between FGFR-regulated N-cadherin adhesion and actin dynamics Based on these findings we propose a positive feed-back loop between N-cadherin and FGFR at adhesion sites limiting N-cadherin-based single-cell migration.
Micropattern-based platform as a physiologically relevant model to study epithelial morphogenesis and nephrotoxicity
Minerva Bosch-Fortea,
Alejo E. Rodriguez-Fraticelli,
Gonzalo Herranz,
Mariam Hachimi,
Maria D. Barea,
Joanne Yong,
Benoit Ladoux,
Fernando Martin-Belmonte
Tubulogenesis in epithelial organs often initiates with the acquisition of apicobasal polarity, giving rise to the formation of small lumens that expand and fuse to generate a single opened cavity. In this study, we present a micropattern-based device engineered to generate epithelial tubes through a process that recapitulates in vivo tubule morphogenesis. Interestingly, tubulogenesis in this device is dependent on microenvironmental cues such as cell confinement, extracellular matrix composition, and substrate stiffness, and our set-up specifically allows the control of these extracellular conditions. Additionally, proximal tubule cell lines growing on micropattems express higher levels of drug transporters and are more sensitive to nephrotoxicity. These tubes display specific morphological defects that can be linked to nephrotoxicity, which would be helpful to predict potential toxicity when developing new compounds. This device, with the ability to recapitulate tube formation in vitro, has emerged as a powerful tool to study the molecular mechanisms involved in organogenesis and, by being more physiologically relevant than existing cellular models, becomes an innovative platform to conduct drug discovery assays.
FBXW5 Promotes Tumorigenesis and Metastasis in Gastric Cancer via Activation of the FAK-Src Signaling Pathway
Mei Shi Yeo,
Vinod Vijay Subhash,
Kazuto Suda,
Hayri Emrah Balcioglu,
Siqin Zhou,
Win Lwin Thuya,
Xin Yi Loh,
Sriganesh Jammula,
Praveen C. Peethala, et al.
Cancers / Molecular Diversity Preservation International (MDPI)
11
(6)
836
(2019)
| Journal
| PDF
F-box/WD repeat-containing protein 5 (FBXW5) is a member of the FBXW subclass of F-box proteins. Despite its known function as a component of the Skpl-Cullin-F-box (SCF) ubiquitin ligase complex, the role of FBXW5 in gastric cancer tumorigenesis and metastasis has not been investigated. The present study investigates the role of FBXW5 in tumorigenesis and metastasis, as well as the regulation of key signaling pathways in gastric cancer; using in-vitro FBXW5 knockdown/overexpression cell line and in-vivo models. In-vitro knockdown of FBXW5 results in a decrease in cell proliferation and cell cycle progression, with a concomitant increase in cell apoptosis and caspase-3 activity. Furthermore, knockdown of FBXW5 also leads to a down regulation in cell migration and adhesion, characterized by a reduction in actin polymerization, focal adhesion turnover and traction forces. This study also delineates the mechanistic role of FBXW5 in oncogenic signaling as its inhibition down regulates RhoA-ROCK 1 (Rho-associated protein kinase 1) and focal adhesion kinase (FAK) signaling cascades. Overexpression of FBXW5 promotes in-vivo tumor growth, whereas its inhibition down regulates in-vivo tumor metastasis. When considered together, our study identifies the novel oncogenic role of FBXW5 in gastric cancer and draws further interest regarding its clinical utility as a potential therapeutic target.
Influence of proliferation on the motions of epithelial monolayers invading adherent strips
Estelle Gauquelin,
Sham Tlili,
Cyprien Gay,
Gregoire Peyret,
Rene-Marc Mege,
Marc A. Fardin,
Benoit Ladoux
Biological systems integrate dynamics at many scales, from molecules, protein complexes and genes, to cells, tissues and organisms. At every step of the way, mechanics, biochemistry and genetics offer complementary approaches to understand these dynamics. At the tissue scale, in vitro monolayers of epithelial cells provide a model to capture the influence of various factors on the motions of the tissue, in order to understand in vivo processes from morphogenesis, cancer progression and tissue remodelling. Ongoing efforts include research aimed at deciphering the roles of the cytoskeleton, of cell-substrate and cell-cell adhesions, and of cell proliferation-the point we investigate here. We show that confined to adherent strips, and on the time scale of a day or two, monolayers move with a characteristic front speed independent of proliferation, but that the motion is accompanied by persistent velocity waves, only in the absence of cell divisions. Here we show that the long-range transmission of physical signals is strongly coupled to cell density and proliferation. We interpret our results from a kinematic and mechanical perspective. Our study provides a framework to understand density-driven mechanisms of collective cell migration.
Cell migration over heterogeneous substrates during wound healing or morphogenetic processes leads to shape changes driven by different organizations of the actin cytoskeleton and by functional changes including lamellipodial protrusions and contractile actin cables. Cells distinguish between cell-sized positive and negative curvatures in their physical environment by forming protrusions at positive curvatures and actin cables at negative curvatures; however, the cellular mechanisms remain unclear. Here, we report that concave edges promote polarized actin structures with actin flow directed towards the cell edge, in contrast to well-documented retrograde flow at convex edges. Anterograde flow and contractility induce a tension anisotropy gradient. A polarized actin network is formed, accompanied by a local polymerization-depolymerization gradient, together with leading-edge contractile actin cables in the front. These cables extend onto non-adherent regions while still maintaining contact with the substrate through focal adhesions. The contraction and dynamic reorganization of this actin structure allows forward movements enabling cell migration over non-adherent regions on the substrate. These versatile functional structures may help cells sense and navigate their environment by adapting to external geometric and mechanical cues.
Cell shape and substrate stiffness drive actin-based cell polarity
Mukund Gupta,
Bryant L. Doss,
Leyla Kocgozlu,
Meng Pan,
Rene-Marc Mege,
Andrew Callan-Jones,
Raphael Voituriez,
Benoit Ladoux
A general trait of living cells is their ability to exert contractile stresses on their surroundings and thus respond to substrate rigidity. At the cellular scale, this response affects cell shape, polarity, and ultimately migration. The regulation of cell shape together with rigidity sensing remains largely unknown. In this article we show that both substrate rigidity and cell shape contribute to drive actin organization and cell polarity. Increasing substrate rigidity affects bulk properties of the actin cytoskeleton by favoring long-lived actin stress fibers with increased nematic interactions, whereas cell shape imposes a local alignment of actin fibers at the cell periphery.
Contact
Tissue Mechanobiology Division Prof. Benoît Ladoux Principal Investigator
Max-Planck-Zentrum für Physik und Medizin Kussmaulallee 2 91054 Erlangen, Germany
