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Intracellular proteolytic activity of cathepsin B is associated with capillary‐like tube formation by endothelial cells in vitro
Author(s) -
Premzl Aleš,
Turk Vito,
Kos Janko
Publication year - 2005
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.20720
Subject(s) - cathepsin b , cathepsin , cathepsin s , intracellular , chemistry , angiogenesis , extracellular , cysteine protease , cathepsin l , matrigel , extracellular matrix , microbiology and biotechnology , biochemistry , umbilical vein , protease , biology , in vitro , enzyme , cancer research
The lysosomal cysteine protease cathepsin B is implicated in degradation of extracellular matrix (ECM), a crucial step in a variety of physiological and pathological processes, including tumor dissemination and angiogenesis. In this study, we analyzed the contribution of extracellular and intracellular cathepsin B activity on the formation of capillary‐like tubular structures by human umbilical vein endothelial cells (HUVECs) grown on Matrigel matrix, using general and specific cysteine protease inhibitors. We demonstrated, by confocal assay using quenched fluorescent protein substrate DQ‐collagen IV, that endothelial cells degrade ECM both intracellularly and pericellularly. Intracellular cathepsin B activity detected by degradation of Z‐Arg‐Arg cresyl violet substrate was co‐localized with the products of DQ‐collagen IV degradation in the perinuclear region and in the capillary‐like tubular structures. Treatment of cells with membrane‐permeable CA‐074 Me effectively abolished intracellular cathepsin B activity, and resulted in reduced tube length (32.3 ± 9.4% at 10 µM), total tubule area (49.6 ± 12.4% at 10 µM), and the number of branch points of tubules (47.5 ± 7.7% at 10 µM) in a dose‐dependent manner. In contrast, CA‐074 (0.1–10 µM), a membrane‐impermeable cathepsin B specific inhibitor, general cysteine protease inhibitors chicken cystatin (5 µM) and E‐64 (10 µM), and the metalloprotease inhibitor Minocycline (10 µM) showed no significant inhibitory effect in our angiogenesis model. These results show that, besides multiple regulatory molecules, intracellular cathepsin B also contributes to the neovascularization process and should be considered as a potential therapeutic target. J. Cell. Biochem. 97: 1230–1240, 2006. © 2005 Wiley‐Liss, Inc.