P53 upregulated by HIF-1α promotes hypoxia-induced G2/M arrest and renal fibrosis in vitro and in vivo. (18th July 2018)

• Record Type: Journal Article
• Authors: Liu, Limin; Zhang, Peng; Bai, Ming; He, Lijie; Zhang, Lei; Liu, Ting; Yang, Zhen; Duan, Menglu; Liu, Minna; Liu, Baojian; Du, Rui; Qian, Qi; Sun, Shiren
• Editors: Lu, Hua
• Is Part Of: Journal of molecular cell biology. Volume 11:Number 5(2019)
• Page Start: 371
• Page End: 382
• Publication Date: 2018-07-18
• Subjects: renal tubulointerstitial fibrosis -- hypoxia -- cell cycle (G2/M) arrest -- p53 -- HIF-1α -- TGF-β; Molecular biology -- Periodicals; 571.605
• DOI: 10.1093/jmcb/mjy042
• Languages: English
• ISSNs: 1674-2788

Abstract

Abstract: Hypoxia plays an important role in the genesis and progression of renal fibrosis. The underlying mechanisms, however, have not been sufficiently elucidated. We examined the role of p53 in hypoxia-induced renal fibrosis in cell culture (human and rat renal tubular epithelial cells) and a mouse unilateral ureteral obstruction (UUO) model. Cell cycle of tubular cells was determined by flow cytometry, and the expression of profibrogenic factors was determined by RT-PCR, immunohistochemistry, and western blotting. Chromatin immunoprecipitation and luciferase reporter experiments were performed to explore the effect of HIF-1α on p53 expression. We showed that, in hypoxic tubular cells, p53 upregulation suppressed the expression of CDK1 and cyclins B1 and D1, leading to cell cycle (G2/M) arrest (or delay) and higher expression of TGF-β, CTGF, collagens, and fibronectin. p53 suppression by siRNA or by a specific p53 inhibitor (PIF-α) triggered opposite effects preventing the G2/M arrest and profibrotic changes. In vivo experiments in the UUO model revealed similar antifibrotic results following intraperitoneal administration of PIF-α (2.2 mg/kg). Using gain-of-function, loss-of-function, and luciferase assays, we further identified an HRE3 region on the p53 promoter as the HIF-1α-binding site. The HIF-1α–HRE3 binding resulted in a sharp transcriptional activation of p53. Collectively, we show the presence of a hypoxia-activated, p53-responsive profibrogenic pathway in the kidney. During hypoxia, p53 upregulation induced by HIF-1α suppresses cell cycle progression, leading to the accumulation of G2/M cells, and activates profibrotic TGF-β and CTGF-mediated signaling pathways, causing extracellular matrix production and renal fibrosis.