Abstract P472: Prorenin Independently Causes Hypertension And Renal and Cardiac Fibrosis In Cyp1a1-Prorenin Transgenic Rats

Abstract

Plasma prorenin is commonly elevated in diabetic patients and appears to predict the development of diabetic nephropathy. However, the pathological role of prorenin is unclear. In this study, a transgenic, inducible, hepatic prorenin-overexpressing rat model was generated and the effect of prorenin in organ injury was examined. Four groups of rats (Cyp1a1 prorenin transgenic male and female rats and nontransgenic littermates) were assigned to receive a diet containing 0.3% of the transgene inducer indole-3-carbinol (I3C) for 4 weeks. Plasma prorenin concentration rose from 23±6 to 208±44 (μg/ml) and MAP increased from 77±5 to 138±17 (mmHg), whereas renal prorenin/renin protein expression was unchanged, in transgenic rats fed with I3C diet. The intact prorenin, not renin, in plasma and urine samples was further observed by western blot analysis. Importantly, transgenic rats with high levels of prorenin developed albuminuria, glomerular and tubulointerstitial fibrosis associated with increased expression of TGFß1, PAI-1, collagen and fibronectin. These rats also exhibited cardiac hypertrophy determined by echocardiography, with elevated ratio of heart weight to body weight. Cardiac collagen in interstitial and perivascular area was prominent, accompanied by the increases in mRNA contents of ANP, BNP, ß-MHC, TGFß1 and PAI-1 in the heart tissue. Furthermore, renal protein levels of phosphor-NF-kB-p65 and MCP-1, NAPDH oxidase and MDA, phospho-ß-catenin and phospho-Akt were dramatically increased in prorenin overexpressed rats. These results indicate that prorenin, without being converted to renin, causes arterial hypertension, renal and cardiac fibrosis independently via the induction of inflammation, oxidative stress and the ß-catenin and Akt-mediated signals.