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.
Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, Research Floor Level 7, Upper Maudlin St., Bristol BS2 8HW, UK.
Helen
H
Williams
Jason L
JL
Johnson
Christopher L
CL
Jackson
Stephen J
SJ
White
Sarah J
SJ
George
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