MMP-2 colocalizes with caveolae on the surface of endothelial cells.
We examined the spatial distribution of MMP-2 on the surface of human endothelial cells using immunofluorescence and confocal microscopy. Staining endothelial cells with MMP-2-specific antibodies revealed a punctate labeling at the basolateral side of the cell periphery, which colocalized with patches of caveolin-1, a major constituent of the caveolae. This colocalization was confirmed by immunogold electron microscopy. MT1-MMP, TIMP-2, and the alphavbeta3 integrin exhibited a similar pattern of staining, with pericellular patches that colocalized with either MMP-2 or caveolin-1. The presence of MT1-MMP and TIMP-2 in caveolae patches could be seen only after treatment with concanavalin A, which induced MMP-2 activation but had no noticeable effect on the pattern or intensity of MMP-2 immunostaining. In contrast, MMP-9 and TIMP-1 staining showed a pattern completely different from that of MMP-2 and TIMP-2, with positive spots uniformly distributed throughout the cell body. Our data show that MMP-2, its activator the MT1-MMP, and its proposed receptor, the alphavbeta3 integrin, are all targeted to the same membrane microdomains on the endothelial cell, thereby restricting matrix proteolysis to a limited microenvironment at the cell surface.
Puyraimond
A
A
Unité 353 INSERM, Hôpital Saint Louis, Paris, 75010, France.
Fridman
R
R
Lemesle
M
M
Arbeille
B
B
Menashi
S
S
D000328:Adult; D021941:Caveolae / Q000737:chemistry*; D051242:Caveolin 1; D022461:Caveolins / Q000032:analysis*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000737:chemistry* / Q000166:cytology; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000032:analysis*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000032:analysis; D019030:Receptors, Vitronectin / Q000032:analysis
C495540:CAV1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D019030:Receptors, Vitronectin; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2