The mechanism of overexpression of retinoic acid receptor alpha in attenuating renal interstitial fibrosis in rats

Abstract

Objective To study the mechanism of overexpression of retinoic acid receptor alpha (RARα) in attenuating renal interstitial fibrosis (RIF) in rats. Methods Forty 6-week-old male SD rats were randomly divided into 4 groups: sham operation group, model group, negative control group and transfection group, with 10 rats in each group.Rats in model group were separated and double ligated with left ureter; rats in sham operation group were not ligated with ureter; rats in transfection group and negative control group were transfected with adeno-associated virus and negative control virus carrying RARα gene on the basis of model group, respectively.All rats were sacrificed 2 weeks later.Left kidney tissues were taken for pathological examination and RIF index was calculated.The expression of collagen Ⅳ (Col-Ⅳ) and fibronectin (FN) in renal tissue was detected by using immunohistochemistry.The expressions of RARα, prohibitin (PHB) and transforming growth factor-beta 1 (TGF-β1) in renal tissue were detected by using real-time fluorescence quantitative polymerase chain reaction(RT-qPCR) and Western blot. Results (1)Compared with sham operation group, the RIF index was significantly increased in model group (22.81±2.43 vs.2.34±0.55, q=24.94, P 0.05), however it significantly decreased in transfection group (14.06±2.99 vs.22.81±2.43, q=10.66, P 0.05); compared with model group, the mRNA and protein expression of RARα, PHB mRNA and protein expression significantly increased, but the TGF-β1 mRNA and protein, Col-Ⅳ and FN protein expression significantly decreased in transfected group (mRNA: 0.86±0.07 vs.0.43±0.17, 0.89±0.11 vs.0.34±0.08, 1.65±0.28 vs.2.97±0.54, all P<0.05; protein: 0.40±0.07 vs.0.25±0.10, 0.45±0.10 vs.0.24±0.07, 0.43±0.08 vs.0.59±0.09, 11.57±0.33 vs.16.01±0.87, 11.67±0.53 vs.14.64±0.32, all P<0.05). (3)Correlation analysis revealed that RARα protein expression was negatively correlated with RIF index, Col-Ⅳ, FN, TGF-β1 (r=-0.78, -0.78, -0.76, -0.76, all P<0.05); PHB protein expression was negatively correlated with RIF index, Col-Ⅳ, FN, TGF-β1 (r=-0.87, -0.87, -0.88, -0.75, all P<0.05); RARα protein was positively correlated with PHB (r=0.85, P<0.05). Conclusion Overexpression of RARα could attenuate RIF by enhancing PHB expression in rats subjected to unilateral ureteral obstruction. Key words: Retinoic acid receptor alpha; Prohibitin; Renal interstitial fibrosis; Transfection