MMP-2 Colocalizes with Caveolae on the Surface of Endothelial Cells

• Published in: Experimental cell research 2001-01, Vol.262 (1), p.28-36
• Main Authors: Puyraimond, Alain, Fridman, Rafael, Lemesle, Monique, Arbeille, Brigitte, Menashi, Suzanne
• Format: Article
• Language: English
• Subjects: Adult; caveolae; Caveolae - chemistry; Caveolin 1; Caveolins - analysis; Cells, Cultured; endothelial cells; Endothelium, Vascular - chemistry; Endothelium, Vascular - cytology; Humans; Matrix Metalloproteinase 2 - analysis; Matrix Metalloproteinases, Membrane-Associated; Metalloendopeptidases - analysis; metalloproteinases; MMP-2; MT1-MMP; Receptors, Vitronectin - analysis
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.2000.5069

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 αvβ3 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 αvβ3 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.