Abstract 194: Angiotensin Ii Induces Fat1 Overexpression and Vascular Smooth Muscle Cell Migration Via Nox1-dependent Reactive Oxygen Species Generation.

Abstract

Fat1 is an atypical cadherin that has been implicated in the control of vascular smooth muscle cell (VSMC) proliferation and migration. NADPH oxidase 1 (Nox1) belongs to the NADPH oxidase family and is an important source of reactive oxygen species (ROS) in VSMCs. Angiotensin II (AngII) induces the expression and/or activation of both Fat1 and Nox1 proteins. We tested the hypothesis that AngII-induced Fat1 activation and VSMC migration are regulated by Nox1-dependent ROS generation. Cultured VSMCs from aortae of adult Sprague-Dawley rats were used. Cells were stimulated for 12h with AngII (1 μmol/L), in the presence or absence of Tempol (1 μmol/L), Apocynin (10 μmol/L), or Valsartan (1 μmol/L). ROS were measured by dihydroethidium and lucigenin assays. Nox1 and/or Fat1 expression was knocked down by siRNA and assessed by western blot analysis with quantitation by densitometry. Cellular migration was evaluated using a Transwell system. AngII stimulated ROS in VSMCs as expected. This effect was blocked by siRNA to Nox1 and by apocynin or valsartan. AngII increased Fat1 (2.17±0.24 arbitrary units (au) vs Ctrl 1.02±0.10, p<0.05), and Nox1 expression (1.95±0.15 au vs Ctrl 0.86±0.15, p<0.05). Tempol, apocynin, valsartan, and Nox1 siRNA prevented AngII-induced Fat1 expression (p<0.05), whereas Fat1 siRNA did not change Nox1 expression. AngII increased VSMC migration (440.7±83.4 cells migrated vs Ctrl 189.0±15.72, p<0.05), and this increase was inhibited by apocynin and valsartan (p<0.05), as well as by Nox1 (227.0±44.27) and Fat1 (192.3±67.4) siRNA (p<0.05). In conclusion, our findings indicate that AngII enhances Fat1 expression and Fat1-dependent VSMC migration via AT1 receptor- and Nox1-dependent ROS generation, and link AngII effects on vascular remodeling to regulation of Fat1 expression.