Three-dimensional collagen matrices induce delayed but sustained activation of gelatinase A in human endothelial cells via MT1-MMP Minh Nguyen, Jacky Arkell, Christopher J. Jackson* Sutton Arthritis Research Laboratory, Royal North Shore Hospital, St Leonards, NSW 2065, Australia Received 18 January 2000; accepted 1 February 2000 Abstract Gelatinase A, a member of the matrix metalloproteinase (MMP) family, plays an important role during angiogenesis. It is constitutively expressed by human endothelial cells as a latent enzyme and requires activation. Thrombin is the only described physiological inducer of gelatinase A in human endothelial cells. In this study, we investigated the mechanisms of gelatinase A activation by another physiological inducer, collagen. Endothelial cells were cultured on various ECM components for 24 h and the conditioned media were assessed for gelatinase A activity using gelatin zymography. The results demonstrated that type I collagen matrix speci®cally activates gelatinase A after 24 h in human umbilical vein and 48 h in neonatal foreskin endothelial cells. In contrast, thrombin activated gelatinase A after only 2 h. Activation 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, a 2 b 1 , but not a 3 b 1 . Our ®ndings, that collagen can provide long- term activation of gelatinase A are likely to be relevant to endothelial cell invasion during angiogenesis. 7 2000 Elsevier Science Ltd. All rights reserved. Keywords: Human endothelial cells; Gelatinase A; Type I collagen matrix; Membrane-type matrix metalloproteinase; Thrombin 1. Introduction Angiogenesis, the formation of new capillaries, occurs in physiological processes such as wound healing and certain diseases, such as cancer and arthritis. An essential event that occurs during angiogenesis is the invasion of the collagen-rich extracellular matrix by endothelial cells. Matrix metalloproteinases (MMPs) are crucial for this process [1]. One member of this family, gelatinase A, is known for its ability to degrade the col- The International Journal of Biochemistry & Cell Biology 32 (2000) 621±631 1357-2725/00/$ - see front matter 7 2000 Elsevier Science Ltd. All rights reserved. PII: S1357-2725(00)00013-3 www.elsevier.com/locate/ijbcb * Corresponding author. Tel.: +612-99266043; fax: +612- 99266269. E-mail address: cjackson@med.usyd.edu.au (C.J. Jackson).