Cleavage of focal adhesion kinase in vascular smooth muscle cells overexpressing membrane-type matrix metalloproteinases.
BACKGROUND
Membrane-type matrix metalloproteinases (MT-MMPs) were initially identified as cell surface activators of MMP-2 (gelatinase A). We have reported that MT1-MMPs and MT3-MMPs are expressed by activated vascular smooth muscle cells (SMCs) and play a role in the regulation of cell function. Overexpression of MT-MMPs results in cell rounding, decreased adherence, and increased migration. Because integrin-mediated cell adhesion regulates these events, we have investigated the functional relationship between MT-MMPs and focal adhesion assembly.


RESULTS
Using adenoviral vectors we show that overexpression of MT-MMPs reduces the number of focal contacts, whereas the cell surface expression of integrin subunits remains unchanged. The 125-kDa focal adhesion kinase (FAK) is cleaved resulting in a 90-kDa fragment under these conditions, and paxillin is partially dissociated from FAK after its cleavage. Pretreatment of cells with BB94, a synthetic MMP inhibitor, rescues cell adhesion and prevents changes in focal adhesions, supporting a potential role for MT-MMP enzymatic activities.


CONCLUSIONS
This study provides the first evidence that MT-MMPs are not only important in matrix degradation but also may affect the function of focal adhesions through FAK cleavage.
Shofuda
Tomoko
T
Division of Vascular Surgery, Department of Surgery, University of Washington School of Medicine, Seattle, Wash 98195-6410, USA.
Shofuda
Ken-ichi
K
Ferri
Nicola
N
Kenagy
Richard D
RD
Raines
Elaine W
EW
Clowes
Alexander W
AW
D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000818:Animals; D002448:Cell Adhesion; D002478:Cells, Cultured / Q000201:enzymology / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006801:Humans; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000235:genetics / Q000502:physiology*; D008856:Microscopy, Fluorescence; D008970:Molecular Weight; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000201:enzymology* / Q000378:metabolism / Q000648:ultrastructure; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000502:physiology
D003598:Cytoskeletal Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; C496063:Pxn protein, rat; D011993:Recombinant Fusion Proteins; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; C496052:Ptk2 protein, rat; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases