Metavinculin Regulation of Cell Cytoskeleton Remodeling in Response to Substrate

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 DESCRIPTION (provided by applicant): Cardiovascular diseases are the leading cause of death in the United States, and hypertension is an important risk factor for cardiovascular diseases. Mediated through cell-extracellular matrix contact, or focal adhesion, increased extracellular matrix stiffness causes aorta structural changes, thus contributes to hypertension development. It remains unclear how focal adhesion regulates responses of vascular smooth muscle cells to increased stiffness. The focal adhesion protein vinculin and its muscle specific splice variant metavinculin are the key components for force transmission. Therefore, our long-term research goal is to delineate the mechanism by which vascular smooth muscle cells respond to changes in extracellular matrix stiffness through metavinculin and vinculin. The goal of this proposal is to characterize metavinculin tail structural features important for actin cytoskeleton remodeling upon changes in extracellular matrix stiffness. Our hypothesis is that metavinculin C-terminal hairpin, released upon actin or phospholipid binding, binds toward vinculin tail C-terminal base to form a heterodimer, which is indispensable for bundling actin fibers in vascular smooth muscle cells. This hypothesis will be addressed using a combination of novel experimental and computational approaches with the following Specific Aims: (1) to characterize metavinculin and vinculin distribution in response to changes in substrate stiffness, (2) to determine the effect of metavinculin tail structure modification on the association of vinculin tail with actin and phospholipid, and (3) to determine metavinculin tail solution structur and locate metavinculin residues that are involved in actin induced metavinculin-vinculin heterodimer formation. Upon completion of the proposed work, we expect to define the role of metavinculin-vinculin heterodimer in cell cytoskeleton remodeling and build structural models for the heterodimer. The results of this study will help reveal vascular remodeling mechanism due to increased vascular stiffness and suggest new interventions to prevent hypertension development, and in turn help reduce morbidity, mortality, and disparity in cardiovascular diseases.