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Speaker Dr Christophe Le Clainche, Institute for Integrative Biology of the Cell (I2BC), Paris-Saclay University
Title Understanding cellular mechanotransduction through in vitro reconstitution of actomyosin-dependent mechanosensitive protein machineries
Host Matthias Krause
Abstract During cell migration, the mechanosensitivity of focal adhesions allows cells to adapt the strength of its adhesion to the force applied by the cytoskeleton and to the physical properties of the extracellular matrix. Although it is well established that the mechanical stretching of the actin-binding protein talin controls this process, the biochemical mechanisms remain largely unexplored. Several studies suggest that talin encodes mechanical information by selecting its binding partners, such as RIAM and vinculin, in response to the force exerted by the actomyosin cytoskeleton. We designed an in vitro microscopy assay with purified proteins to study this mechanism. In this assay, actomyosin force controls the binding of RIAM and vinculin to talin immobilized on a micropatterned surface. We demonstrate that actomyosin triggers the sequential exchange of RIAM for vinculin on multiple domains of talin. Finally, by combining kinetic studies in fluorescence spectroscopy and single-molecule observation in fluorescence microscopy, we determined that the talin-vinculin complex, that results from this mechanosensitive process, controls actin assembly.