Regulation of focal complex composition and disassembly by the calcium-dependent protease calpain.

Bhatt A, Kaverina I, Otey C, Huttenlocher A
J Cell Sci. 2002 115 (Pt 17): 3415-25

PMID: 12154072

Cell migration requires the regulated and dynamic turnover of adhesive complexes. We have previously demonstrated that the calcium-dependent protease, calpain, regulates the organization of adhesive complexes and cell detachment during cell migration. Evidence is now provided that inhibiting calpain through over-expression of the endogenous inhibitor of calpain, calpastatin, and pharmacological inhibitors results in an inhibition of adhesive complex disassembly with stabilization of GFP-vinculin and GFP/RFP-zyxin at the cell periphery. Calpain was also required for the microtubule-mediated turnover of adhesive complex sites after nocodazole wash-out, suggesting that calpain may mediate focal complex disassembly downstream of microtubules. Using dual imaging of RFP-zyxin and GFP-alpha-actinin, we observed a temporal and spatial relationship between alpha-actinin localization to focal contacts and the subsequent disassembly or translocation of RFP-zyxin containing focal complexes in areas of cell retraction. Calpain inhibition disrupted alpha-actinin localization to zyxin-containing focal contacts and focal complex disassembly or translocation to the cell center. In addition, disrupting alpha-actinin localization to focal complexes through expression of the alpha-actinin rod domain, but not the head domain, resulted in inhibition of focal adhesion disassembly similar to calpain inhibition. Our studies suggest a novel mechanism of action whereby calpain may modulate alpha-actinin localization into focal complexes and their subsequent disassembly or translocation.

MeSH Terms (26)

Actinin Animals Calcium Calcium-Binding Proteins Calpain Cell Adhesion Cell Movement Cells, Cultured CHO Cells Cricetinae Cysteine Proteinase Inhibitors Cytoskeletal Proteins Fibroblasts Focal Adhesions Glycoproteins Goldfish Green Fluorescent Proteins Humans Luminescent Proteins Metalloproteins Microscopy, Video Microtubules Nocodazole Recombinant Fusion Proteins Vinculin Zyxin

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