Inhibitory effects of recombinant RTS-jerdostatin on integrin α1β1 function during adhesion, migration and proliferation of rat aortic smooth muscle cells and angiogenesis

Jerdostatin, a short RTS-disintegrin cloned from venom gland mRNA of Protobothrops jerdonii, selectively blocks the adhesion of alpha 1 beta 1 integrin to collagen IV. Integrin alpha 1 beta 1 is highly expressed in smooth muscle cells (SMC) surrounding small blood vessels and vascular endothelial cells. Vascular SMC adhesion, migration and proliferation are important processes during normal vascular development. Using recombinant jerdostatin we have investigated the role of the alpha 1 beta 1 integrin on the adhesion of vascular SMC to collagen IV, and the potential relevance of blocking this crucial component of focal adhesions as an anti-angiogenic strategy. Our results show that jerdostatin does not interact with canonical collagen-binding site on the isolated A-domain of the alpha 1 integrin subunit. r-Jerdostatin inhibited the adhesion of RASMCs to immobilized CB3 fragment in a dose-dependent manner, triggering to round-up, retraction, and finally detachment of the cells. r-Jerdostatin did not affect the adhesion of human SMCs to CB3, presumably because the high expression of alpha 1 beta 1 integrin compensated for alpha 1 beta 1 integrin blockage by jerdostatin. r-Jerdostatin dose-dependently inhibited alpha 1 beta 1 integrin-dependent HUVEC tube formation. However, VEGF-driven tube formation in the matrigel assay was only completely abolished when binding of integrin alpha 1 beta 1 to collagen was also inhibited by the C-type lectin-like rhodocetin. As a whole, our work emphasizes the relevance of using specific inhibitors for dissecting the role of alpha 1 beta 1 integrin in physiological and pathological conditions. (C) 2013 Elsevier Ltd. All rights reserved.