Abstract 375: Knockdown of (Pro)renin Receptor and Wnt3a Improves Diabetic Albuminuria Via (Pro)renin Receptor-TGFβ1-Wnt3a Signaling Pathways

Abstract

Recently we demonstrated involvement of (pro)renin receptor (PRR) in renal inflammation of diabetic rats. We hypothesized that in presence of hyperglycemia, PRR upregulates renal Wnt3a and the extracellular matrix component fibronectin (FN) via TGFβ1 signaling pathway, leading to development of albuminuria. Rats underwent unilateral nephrectomy of right kidneys. Diabetes (DM) was induced by IP streptozocin 65 mg/kg. Lentiviral particles constructed with shRNA of PRR or Wnt3a were injected under the capsule of left kidneys of diabetic rats (n=6 each group) respectively. Control shRNA lentiviral particles were also delivered to the kidneys of normal (n=6) and diabetic (n=6) rats. Studies were conducted for 4 weeks. At the end of study, we monitored renal expressions of PRR, TGFβ1, Wnt3a and FN by quantitative RT-PCR and Western blotting, and 24h urine albumin to creatinine ratio (UACR). Compared to control, DM rats had increases in renal mRNA and protein expressions of PRR by 65% and 40% (p<0.01), TGFβ1 by 57% and 46% (p<0.05) and Wnt3a by 205% and 50% (p<0.01) respectively. Renal mRNAs and proteins of PRR and Wnt3a, and UACR in diabetic rats were significantly reduced by corresponding PRR- or Wnt3a-shRNA (20.14% and 46.77%, p<0.001; 37.80% and 24.09%, p<0.01; 40.00% and 55.29%, p<0.01) respectively. There were no changes in cardiac or hepatic expressions of PRR and Wnt3a in response to shRNAs treatments. PRR shRNA significantly reduced TGFβ1 and Wnt3a mRNA and protein expressions (67% and 30%, p<0.01 and 24.61% and 66.83%, p<0.01) respectively. In DM rats, TGFβI receptor inhibition by SD208 decreased Wnt3a mRNA and protein expression (46% and 37%, p<0.01). FN mRNA expression increased by 79% (p<0.01) in the kidneys of DM rats. The increase in FN mRNA expression was attenuated by PRR shRNA and TGFβ receptor blockade by 73% (p<0.01) and 97% (p<0.01) in DM rats. Both PRR and Wnt3a shRNAs attenuated the DM-induced glomerular hypertrophy. We conclude that in hyperglycemic state, PRR upregulates renal Wnt3a and FN via TGFβ1 signaling pathway. Blockade of PRR-Wnt3a signaling pathway improves diabetic albuminuria.