Three-dimensional collagen matrices induce delayed but sustained activation of gelatinase A in human endothelial cells via MT1-MMP

Gelatinase A, a member of the matrix metalloproteinase (MMP) family, plays an important role during angiogenesis. It is constitutively expressed by hu man endothelial cells as a latent enzyme and requires activation. Thrombin is the only described physiological inducer of gelatinase A in human endoth elial cells. In this study, we investigated the mechanisms of gelatinase A activation by another physiological inducer, collagen. Endothelial cells we re cultured on various ECM components for 24 h and the conditioned media we re assessed for gelatinase A activity using gelatin zymography. The results demonstrated that type I collagen matrix specifically activates gelatinase A after 24 h in human umbilical vein and 48 h in neonatal foreskin endothe lial cells. In contrast, thrombin activated gelatinase A after only 2 h. Ac tivation by collagen was sustained over long periods of time in culture (96 h). Unlike thrombin-induced activation, collagen required active membrane type 1-MMP (MT1-MMP) on the endothelial cell surface to activate gelatinase A. In addition, collagen-induced activation of gelatinase A was inhibited by antibodies to the integrin receptor, alpha(2)beta(1), but not alpha(3)be ta(1). Our findings, that collagen can provide longterm activation of gelat inase A are likely to be relevant to endothelial cell invasion during angio genesis. (C) 2000 Elsevier Science Ltd. All rights reserved.