A NOVEL REGULATORY EFFECT OF AT1 RECEPTOR-INTERACTING MOLECULE ON VASCULAR SMOOTH MUSCLE CELLS

Abstract

Objective: Previous studies reported that the production of superoxide is modulated by many factors including Ang II - AT1 receptor signaling. One of the major sources of superoxide in the aorta is NADPH oxidase located in the smooth muscle cells. The NADPH oxidase complex in the vascular smooth muscle cells consists of p22phox, Rac1, and Nox1. Previous studies showed that the carboxy-terminal cytoplasmic domain of AT1 receptor is involved in the control of receptor internalization and in linking receptor-mediated signal transduction to the specific biological response. Design and method: We previousy cloned a novel molecule interacting with carboxy-terminal domain of AT1 receptor, which we named ATRAP (for AT1 receptor-associated protein), using the yeast two-hybrid strategy. In this study, we tested the hypothesis that vascular smooth muscle cells express ATRAP and that ATRAP modulates Ang II-induced proliferative activity and oxidative stress in vascular smooth muscle cells. We identified that the ATRAP mRNA and protein were endogeneously expressed in VSMC, and found a colocalization of ATRAP and AT1 receptor in Ang II-stimulated VSMC. Results: The results of gain-of-function studies by adenoviral gene transfer demonstrated that overexpression of ATRAP significantly inhibited Ang II-mediated increases in c-fos gene transcription, BrdU incorpoaration, and mRNAs expression of NADPH oxidase complex (p < 0.05, n = 6). Conclusions: These results indicate that ATRAP significantly attenuates Ang II-mediated proliferative activity and oxidative stress in vascular smooth muscle cells, and may suggest a novel strategy to inhibit cardiovascular disease such as arteriosclerosis and hypertension.