Identification and characterisation of transforming growth factor beta-regulated vascular smooth muscle cell genes

Transforming growth factor beta (TGF beta) is thought to play an important role in the development and/or progression of a number of vascular disorders through its numerous effects on vascular smooth muscle cells (VSMCs). In this study we sought to identify and characterize TGF beta-regulated VSMC genes using differential mRNA display (DD-RT-PCR) analysis of RNA isolated from TGF beta-stimulated cultured rat aortic VSMCs. Northern blot analysis was used to demonstrate that five of 19 differentially displayed bands identified represented VSMC transcripts differentially expressed by TGF beta, DNA sequencing revealed that three of these TGF beta regulated genes were novel whilst the remaining two were identified through homologies to known genes. One TGF beta upregulated transcript represented the protease cathepsin B, Since cathepsins mag play a role in TGF beta activation, an enzyme-linked immunosorbent assay (ELISA) for active TGF beta 1 was used to demonstrate an effect of cathepsin B on TGF beta 1 activation in vitro using both recombinant and human serum platelet-derived latent TGF beta 1 as substrate, These results suggest that induction of cathepsin B by TGF beta, and its ability to activate TGF beta 1, mag. represent a mechanism whereby the autocrine action of TGF beta Is facilitated through expression of a protein which can process its latent form. (C) 2000 Academic Press.