Biophysical Society Thematic Meeting| Aussois 2019

Biology and Physics Confront Cell-Cell Adhesion

Wednesday Speaker Abstracts

HYDRAULIC FRACTURE OF MEMBRANE ADHESION CONTACTS Margarita Staykova Durham University, United Kingdom

What happens to adhering cells when they expel water through their membranes; is adhesion lost or are the cell contacts being remodelled? It turns out these questions are of wide biological relevance- from osmotically shrinking cells to active pumping of water in embryo tissues and formation of lumen. To get a quantitative understanding we use biomimetic model system, consisting of giant unilamellar vesicles coupled to a supported lipid bilayer or to other vesicles via strong biotin-neutravidin links, or via the much weaker cadherin bonds. Upon osmotic vesicle shrinking, the adjacent membranes locally disconnect and deform into water-filled pockets, also observed in cells. At the same time, the adhesion bonds are sheared away from the disconnecting membranes, and later recover with time. Using our simplified system, we are able to elucidate the mechanisms of water pocket formation and determine its dependance on the membrane water permeability, the bond properties and the magnitude of the osmotic shock. The evolution of the water pockets provide some hints to the behaviour of the plasma membrane during cell contact remodeling.

FORCE TRANSMISSION AT CELL ADHESIONS Nicolas Borghi 1 ; 1 CNRS, Institut Jacques Monod, Paris, France

In multicellular organisms, cells generate and undergo mechanical forces that may shape tissues and regulate genetic programs, but the underlying mechanisms remain largely unknown. Using genetically encoded biosensors of molecular tension, it is now possible to monitor in space and time the forces exerted on specific cell adhesion proteins in situ. Doing so, we have assessed in cell culture models how adhesion proteins respond to intra- and extracellular mechanical cues, and how their tension relates to the activation of cell signaling pathways and cell-scale forces upon induction of generic morphogenetic processes. Our results reveal varied mechanisms for force transmission across scales and their efficiencies, and how cell mechanosensation may arise from these processes.

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