Pregnane X receptor alleviates renal fibrosis by inhibiting the activation of Wnt/β-catenin signaling pathway via interacting with p53
Authors: Ming Wenhua , Du Chunxiu , Guan Youfei , Xiaoyan Zhang 
Published: May 2023

Renal fibrosis is a common pathological feature of chronic kidney disease (CKD), leading to the loss of nephrons and impairment of renal function. Pregnane X receptor (PXR), a member of nuclear receptor superfamily, has been reported with a constitutive renal expression and protective effect in acute kidney injury (AKI). However, the role of PXR in renal fibrosis remains unclear. The aim of this study was to investigate the role and mechanism of PXR in renal fibrosis. Renal fibrosis model was established in C57BL/6J wild-type mice, PXR gene knockout (PXR-/-) mice and humanized PXR (hPXR) mice by both 0.2% adenine diet model and unilateral ureteral obstruction model (UUO). We demonstrated that the activation of PXR by its agonist pregnenolone-16α-carbonitrile (PCN) reduced urinary albumin, serum creatinine and urea nitrogen content, alleviated renal tubular injury and renal interstitial fibrosis in mice induced by 0.2% adenine diet. PCN treatment attenuated adenine-induced upregulation of P-smad3, αSMA, Collagen I and Fibronectin. In addition, the expression of P-smad3 in the nucleus was also inhibited by PCN. We also performed the experiments in UUO model and got the same results. In addition, we treated hPXR mice with rifampicin (RIF) which is a human PXR agonist and found that RIF showed similar therapeutic effect in 0.2% adenine diet model. On the contrary, PXR knockout aggravated renal fibrosis induced by 0.2% adenine diet and UUO. Wnt/β-catenin signaling pathway has been reported to be closely involved in renal fibrosis. We detected the expressions of all Wnt famliy genes located in the kidney and found that PCN significantly inhibited the expression of Wnt7a in vivo and in vitro. Expression and activation of β-catenin, a key factor of Wnt/β-catenin signaling pathways, was also inhibited by PCN. Double immunofluorescence and Co-IP assays revealed that p53 and PXR co-localized and interacted with each other in mouse renal proximal tubular cell line. ChIP assay indicated that p53 effectively collect the chromatin fragment of Wnt7a promoter which was predicted containing p53 binding site by the PROMO database. PXR activation drastically reduced the binding of p53 in Wnt7a promoter. In addition, dual luciferase analysis showed that p53 overexpression promoted Wnt7a transcription, but this effect was inhibited by PXR activation. Furthermore, Furthermore, overexpression of p53 increased the expression of Wnt7a, β-catenin and their downstream target gene Fibronectin, while Wnt7a knock down abolished this effect. Taken together, our results demonstrated that PXR plays a protective role in renal fibrosis, PXR inhibits Wnt7a/β-catenin signaling pathway by interacting with p53. The present study indicated that PXR might be a new target for clinical treatment of renal fibrosis in the future. This work was supported by the National Natural Science Foundation of China Grants 81970606 (to X.Z.) and 81970595 (to Y.G.). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.