Mechanical Information Processing by the Actin Cytoskeleton

Adherent cells sense varied mechanical cues; however, the mechanisms by which these input signals are processed to control cell physiological functions is not known. Mechanosensing and force generation in tissues are generally driven by the actomyosin network and adhesion components (focal adhesions and adherens junctions) that control tissue homeostasis. A ubiquitous family of LIM (Lin11, Isl- 1, and Mec-3) domain proteins is associated with mechanotransductive structures, and yet how mechanical information is sensed and processed across a tissue remains elusive. Here, we demonstrate tunability of LIM domain protein localization and function in endothelial cells by altering various intracellular and extracellular mechanical cues such as shear stress, contractility, and matrix rigidity. For instance, Zyxin, which predominantly localizes to stress fibers and focal adhesions, can be redirected to adherens junctions and tricellular vertices by altering matrix rigidity. In addition, we observe that shear stresses experienced by vascular endothelial cells drive the differential localization of Zyxin and FHL2. Functionally, the expression levels and localization of LIM proteins precisely control how cells mechanosense and align in response to shear stress. Altogether, we identify and describe the intracellular and extracellular mechanical cues that trigger the differential localization of LIM domain proteins. Using novel techniques such as photo-proximity spatial profiling of proteins, phosphoproteomics and machine learning, we are exploring the functions and mechanotransduction pathways downstream of the force-dependent tuning of LIM protein localization.