@article{676, abstract = {The segregation of different cell types into distinct tissues is a fundamental process in metazoan development. Differences in cell adhesion and cortex tension are commonly thought to drive cell sorting by regulating tissue surface tension (TST). However, the role that differential TST plays in cell segregation within the developing embryo is as yet unclear. Here, we have analyzed the role of differential TST for germ layer progenitor cell segregation during zebrafish gastrulation. Contrary to previous observations that differential TST drives germ layer progenitor cell segregation in vitro, we show that germ layers display indistinguishable TST within the gastrulating embryo, arguing against differential TST driving germ layer progenitor cell segregation in vivo. We further show that the osmolarity of the interstitial fluid (IF) is an important factor that influences germ layer TST in vivo, and that lower osmolarity of the IF compared with standard cell culture medium can explain why germ layers display differential TST in culture but not in vivo. Finally, we show that directed migration of mesendoderm progenitors is required for germ layer progenitor cell segregation and germ layer formation.}, author = {Krens, Gabriel and Veldhuis, Jim and Barone, Vanessa and Capek, Daniel and Maître, Jean-Léon and Brodland, Wayne and Heisenberg, Carl-Philipp J}, issn = {09501991}, journal = {Development}, number = {10}, pages = {1798 -- 1806}, publisher = {Company of Biologists}, title = {{Interstitial fluid osmolarity modulates the action of differential tissue surface tension in progenitor cell segregation during gastrulation}}, doi = {10.1242/dev.144964}, volume = {144}, year = {2017}, } @article{1923, abstract = {We derive the equations for a thin, axisymmetric elastic shell subjected to an internal active stress giving rise to active tension and moments within the shell. We discuss the stability of a cylindrical elastic shell and its response to a localized change in internal active stress. This description is relevant to describe the cellular actomyosin cortex, a thin shell at the cell surface behaving elastically at a short timescale and subjected to active internal forces arising from myosin molecular motor activity. We show that the recent observations of cell deformation following detachment of adherent cells (Maître J-L et al 2012 Science 338 253-6) are well accounted for by this mechanical description. The actin cortex elastic and bending moduli can be obtained from a quantitative analysis of cell shapes observed in these experiments. Our approach thus provides a non-invasive, imaging-based method for the extraction of cellular physical parameters.}, author = {Berthoumieux, Hélène and Maître, Jean-Léon and Heisenberg, Carl-Philipp J and Paluch, Ewa and Julicher, Frank and Salbreux, Guillaume}, journal = {New Journal of Physics}, publisher = {IOP Publishing Ltd.}, title = {{Active elastic thin shell theory for cellular deformations}}, doi = {10.1088/1367-2630/16/6/065005}, volume = {16}, year = {2014}, } @article{2469, abstract = {Cadherins are transmembrane proteins that mediate cell–cell adhesion in animals. By regulating contact formation and stability, cadherins play a crucial role in tissue morphogenesis and homeostasis. Here, we review the three major unctions of cadherins in cell–cell contact formation and stability. Two of those functions lead to a decrease in interfacial ension at the forming cell–cell contact, thereby promoting contact expansion — first, by providing adhesion tension that lowers interfacial tension at the cell–cell contact, and second, by signaling to the actomyosin cytoskeleton in order to reduce cortex tension and thus interfacial tension at the contact. The third function of cadherins in cell–cell contact formation is to stabilize the contact by resisting mechanical forces that pull on the contact.}, author = {Maître, Jean-Léon and Heisenberg, Carl-Philipp J}, journal = {Current Biology}, number = {14}, pages = {R626 -- R633}, publisher = {Cell Press}, title = {{Three functions of cadherins in cell adhesion}}, doi = {10.1016/j.cub.2013.06.019}, volume = {23}, year = {2013}, } @article{2884, author = {Maître, Jean-Léon and Berthoumieux, Hélène and Krens, Gabriel and Salbreux, Guillaume and Julicher, Frank and Paluch, Ewa and Heisenberg, Carl-Philipp J}, journal = {Medecine Sciences}, number = {2}, pages = {147 -- 150}, publisher = {Éditions Médicales et Scientifiques}, title = {{Cell adhesion mechanics of zebrafish gastrulation}}, doi = {10.1051/medsci/2013292011}, volume = {29}, year = {2013}, } @article{2951, abstract = {Differential cell adhesion and cortex tension are thought to drive cell sorting by controlling cell-cell contact formation. Here, we show that cell adhesion and cortex tension have different mechanical functions in controlling progenitor cell-cell contact formation and sorting during zebrafish gastrulation. Cortex tension controls cell-cell contact expansion by modulating interfacial tension at the contact. By contrast, adhesion has little direct function in contact expansion, but instead is needed to mechanically couple the cortices of adhering cells at their contacts, allowing cortex tension to control contact expansion. The coupling function of adhesion is mediated by E-cadherin and limited by the mechanical anchoring of E-cadherin to the cortex. Thus, cell adhesion provides the mechanical scaffold for cell cortex tension to drive cell sorting during gastrulation.}, author = {Maître, Jean-Léon and Berthoumieux, Hélène and Krens, Gabriel and Salbreux, Guillaume and Julicher, Frank and Paluch, Ewa and Heisenberg, Carl-Philipp J}, journal = {Science}, number = {6104}, pages = {253 -- 256}, publisher = {American Association for the Advancement of Science}, title = {{Adhesion functions in cell sorting by mechanically coupling the cortices of adhering cells}}, doi = {10.1126/science.1225399}, volume = {338}, year = {2012}, } @article{3396, abstract = {Facial branchiomotor neurons (FBMNs) in zebrafish and mouse embryonic hindbrain undergo a characteristic tangential migration from rhombomere (r) 4, where they are born, to r6/7. Cohesion among neuroepithelial cells (NCs) has been suggested to function in FBMN migration by inhibiting FBMNs positioned in the basal neuroepithelium such that they move apically between NCs towards the midline of the neuroepithelium instead of tangentially along the basal side of the neuroepithelium towards r6/7. However, direct experimental evaluation of this hypothesis is still lacking. Here, we have used a combination of biophysical cell adhesion measurements and high-resolution time-lapse microscopy to determine the role of NC cohesion in FBMN migration. We show that reducing NC cohesion by interfering with Cadherin 2 (Cdh2) activity results in FBMNs positioned at the basal side of the neuroepithelium moving apically towards the neural tube midline instead of tangentially towards r6/7. In embryos with strongly reduced NC cohesion, ectopic apical FBMN movement frequently results in fusion of the bilateral FBMN clusters over the apical midline of the neural tube. By contrast, reducing cohesion among FBMNs by interfering with Contactin 2 (Cntn2) expression in these cells has little effect on apical FBMN movement, but reduces the fusion of the bilateral FBMN clusters in embryos with strongly diminished NC cohesion. These data provide direct experimental evidence that NC cohesion functions in tangential FBMN migration by restricting their apical movement.}, author = {Stockinger, Petra and Heisenberg, Carl-Philipp J and Maître, Jean-Léon}, journal = {Development}, number = {21}, pages = {4673 -- 4683}, publisher = {Company of Biologists}, title = {{Defective neuroepithelial cell cohesion affects tangential branchiomotor neuron migration in the zebrafish neural tube}}, doi = {10.1242/dev.071233}, volume = {138}, year = {2011}, } @article{3397, abstract = {Recent advances in microscopy techniques and biophysical measurements have provided novel insight into the molecular, cellular and biophysical basis of cell adhesion. However, comparably little is known about a core element of cell–cell adhesion—the energy of adhesion at the cell–cell contact. In this review, we discuss approaches to understand the nature and regulation of adhesion energy, and propose strategies to determine adhesion energy between cells in vitro and in vivo.}, author = {Maître, Jean-Léon and Heisenberg, Carl-Philipp J}, journal = {Current Opinion in Cell Biology}, number = {5}, pages = {508 -- 514}, publisher = {Elsevier}, title = {{The role of adhesion energy in controlling cell-cell contacts}}, doi = {10.1016/j.ceb.2011.07.004}, volume = {23}, year = {2011}, } @article{3379, abstract = {The process of gastrulation is highly conserved across vertebrates on both the genetic and morphological levels, despite great variety in embryonic shape and speed of development. This mechanism spatially separates the germ layers and establishes the organizational foundation for future development. Mesodermal identity is specified in a superficial layer of cells, the epiblast, where cells maintain an epithelioid morphology. These cells involute to join the deeper hypoblast layer where they adopt a migratory, mesenchymal morphology. Expression of a cascade of related transcription factors orchestrates the parallel genetic transition from primitive to mature mesoderm. Although the early and late stages of this process are increasingly well understood, the transition between them has remained largely mysterious. We present here the first high resolution in vivo observations of the blebby transitional morphology of involuting mesodermal cells in a vertebrate embryo. We further demonstrate that the zebrafish spadetail mutation creates a reversible block in the maturation program, stalling cells in the transition state. This mutation creates an ideal system for dissecting the specific properties of cells undergoing the morphological transition of maturing mesoderm, as we demonstrate with a direct measurement of cell–cell adhesion.}, author = {Row, Richard and Maître, Jean-Léon and Martin, Benjamin and Stockinger, Petra and Heisenberg, Carl-Philipp J and Kimelman, David}, journal = {Developmental Biology}, number = {1}, pages = {102 -- 110}, publisher = {Elsevier}, title = {{Completion of the epithelial to mesenchymal transition in zebrafish mesoderm requires Spadetail}}, doi = {10.1016/j.ydbio.2011.03.025}, volume = {354}, year = {2011}, } @phdthesis{3273, author = {Maître, Jean-Léon}, issn = {2663-337X}, publisher = {Institute of Science and Technology Austria}, title = {{Mechanics of adhesion and de‐adhesion in zebrafish germ layer progenitors}}, year = {2011}, }