MMP-7 mediates cleavage of N-cadherin and promotes smooth muscle cell apoptosis.
OBJECTIVE
Vascular smooth muscle cell (VSMC) apoptosis can lead to thinning of the fibrous cap and plaque instability. We previously showed that cell-cell contacts mediated by N-cadherin reduce VSMC apoptosis. This study aimed to determine whether matrix-degrading metalloproteinase (MMP)-dependent N-cadherin cleavage causes VSMC apoptosis.


RESULTS
Induction of human VSMC apoptosis using different approaches, including 200 ng/mL Fas ligand (Fas-L) and culture in suspension, caused N-cadherin cleavage and resulted in the appearance of a C-terminal fragment of N-cadherin (approximately 35 kDa). Appearance of this fragment during apoptosis was inhibited by 47% with the broad-spectrum MMP inhibitor BB-94. We observed retarded cleavage of N-cadherin after treatment with Fas-L in aortic mouse VSMCs lacking MMP-7. Furthermore, VSMC apoptosis, measured by quantification of cleaved caspase-3, was 43% lower in MMP-7 knockout mouse VSMCs compared with wild-type VSMCs following treatment with Fas-L. Addition of recombinant active MMP-7 increased the amount of N-cadherin fragment by 82% and augmented apoptosis by 53%. The involvement of MMP-7 was corroborated using human cells, where a MMP-7 selective inhibitor reduced the amount of fragment formed by 51%. Importantly, we observed that treatment with Fas-L increased levels of active MMP-7 by 80%. Finally, we observed significantly increased cleavage of N-cadherin, MMP-7 activity, and apoptosis in human atherosclerotic plaques compared with control arteries, and a significant reduction in apoptosis in atherosclerotic plaques from MMP-7 knockout mice.


CONCLUSIONS
This study demonstrates that MMP-7 is involved in the cleavage of N-cadherin and modulates VSMC apoptosis, and may therefore contribute to plaque development and rupture.
Williams
Helen
H
Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, Research Floor Level 7, Upper Maudlin St., Bristol BS2 8HW, UK.
Johnson
Jason L
JL
Jackson
Christopher L
CL
White
Stephen J
SJ
George
Sarah J
SJ
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001057:Apolipoproteins E / Q000172:deficiency / Q000235:genetics; D017209:Apoptosis; D050197:Atherosclerosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D015820:Cadherins / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D053222:Fas Ligand Protein / Q000378:metabolism; D006801:Humans; D020783:Matrix Metalloproteinase 7 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D010649:Phenylalanine / Q000031:analogs & derivatives / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D012421:Rupture; D013876:Thiophenes / Q000494:pharmacology; D013997:Time Factors
D015703:Antigens, CD; D001057:Apolipoproteins E; C050361:CDH2 protein, human; D015820:Cadherins; C489083:Cdh2 protein, mouse; D053222:Fas Ligand Protein; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D013876:Thiophenes; D010649:Phenylalanine; C080985:batimastat; C505409:Casp3 protein, mouse; D053148:Caspase 3; C060932:MMP7 protein, human; D020783:Matrix Metalloproteinase 7