Vinculin is proteolyzed by calpain during platelet aggregation: 95 kDa cleavage fragment associates with the platelet cytoskeleton

K Serrano, DV Devine - Cell motility and the cytoskeleton, 2004 - Wiley Online Library
Cell motility and the cytoskeleton, 2004Wiley Online Library
The focal adhesion protein vinculin contributes to cell attachment and spreading through
strengthening of mechanical interactions between cell cytoskeletal proteins and surface
membrane glycoproteins. To investigate whether vinculin proteolysis plays a role in the
influence vinculin exerts on the cytoskeleton, we studied the fate of vinculin in activated and
aggregating platelets by Western blot analysis of the platelet lysate and the cytoskeletal
fractions of differentially activated platelets. Vinculin was proteolyzed into at least three …
Abstract
The focal adhesion protein vinculin contributes to cell attachment and spreading through strengthening of mechanical interactions between cell cytoskeletal proteins and surface membrane glycoproteins. To investigate whether vinculin proteolysis plays a role in the influence vinculin exerts on the cytoskeleton, we studied the fate of vinculin in activated and aggregating platelets by Western blot analysis of the platelet lysate and the cytoskeletal fractions of differentially activated platelets. Vinculin was proteolyzed into at least three fragments (the major one being ∼95 kDa) within 5 min of platelet activation with thrombin or calcium ionophore. The 95 kDa vinculin fragment shifted cellular compartments from the membrane skeletal fraction to the cortical cytoskeletal fraction of lysed platelets in a platelet aggregation‐dependent manner. Vinculin cleavage was inhibited by calpeptin and E64d, indicating that the enzyme responsible for vinculin proteolysis is calpain. These calpain inhibitors also inhibited the translocation of full‐length vinculin to the cytoskeleton. We conclude that cleavage of vinculin and association of vinculin cleavage fragment(s) with the platelet cytoskeleton is an activation response that may be important in the cytoskeletal remodeling of aggregating platelets. Cell Motil. Cytoskeleton 58:242–252, 2004. © 2004 Wiley‐Liss, Inc.
Wiley Online Library