Abstract 14980: ADAMTS1 Play Roles In Endothelial Cell Apoptosis

Background: We have previously reported that ADAMTS1 (A disintegrin and metalloprotease with thrombospondin motifs), a member of the metalloproteinase family, acts as anti-angiogenic molecule. This inhibitory effect has been explained by its protease activity including the proteolysis of thrombospondin-1 (TSP-1). The aim of this study was to clarify the biological role of ADAMTS1 on endothelial cells. Methods: We produced ADAMTS1 deficient mice (ADAMTS1 KO mice) and aortic endothelial cells were isolated from ADAMTS1 KO mice and wild type mice. We examined the effect on endothelial cell apoptosis by stimulation with tumor necrosis factor-alpha (TNF-α) and ADAMTS1 expression levels were examined by quantitative real-time RT-PCR. We next examined the mRNA expressions of apoptosis-related genes Bax and Bcl-2 in TNF-α-stimulated endothelial cells. Finally, we examined the effect of adenoviral gene transfer of ADAMTS1 on endothelial cells with two constructs, full length of ADAMTS1 and protease domain-truncated ADAMTS1. Results: In the wild type endothelial cells, endogenous ADAMTS1 was increased approximately 5-fold by TNF-α stimulation after 24 hrs, while endothelial cells derived from ADAMTS1 KO mice did not produce any ADAMTS1. MTT assay revealed that ADAMTS deficient cell were more viable under TNF-α stimulation. Bax mRNA levels were significantly attenuated in the ADAMTS1 deficient endothelial cells. Adenoviral gene transfer of ADAMTS1 in HUVEC demonstrated that ADAMTS1 overexpression enhanced endothelial cell apoptosis via a protease-independent mechanism. Taken together, we found that the novel inhibitory mechanism of ADAMTS1 on endothelial cells that was mediated in a protease-independent manner. Conclusion: ADAMTS1 play roles in endothelial cell apoptosis.