MMP-2 colocalizes with caveolae on the surface of endothelial cells

Exp Cell Res. 2001 Jan 1;262(1):28-36. doi: 10.1006/excr.2000.5069.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Caveolae / chemistry*
  • Caveolin 1
  • Caveolins / analysis*
  • Cells, Cultured
  • Endothelium, Vascular / chemistry*
  • Endothelium, Vascular / cytology
  • Humans
  • Matrix Metalloproteinase 2 / analysis*
  • Matrix Metalloproteinases, Membrane-Associated
  • Metalloendopeptidases / analysis
  • Receptors, Vitronectin / analysis

Substances

  • CAV1 protein, human
  • Caveolin 1
  • Caveolins
  • Receptors, Vitronectin
  • Matrix Metalloproteinases, Membrane-Associated
  • Metalloendopeptidases
  • Matrix Metalloproteinase 2