Hypoxia inducible factor-1 promotes liver fibrosis in nonalcoholic fatty liver disease by activating PTEN/p65 signaling pathway

Obesity is a major contributor to the development of steatohepatitis and fibrosis from nonalcoholic fatty liver disease (NAFLD). Hypoxia aggravates progression of NAFLD. In mice on high-fat diet (HFD), hepatic steatosis leads to liver tissue hypoxia, evidenced by accumulation of hypoxia inducible factor-1-alpha (HIF-1 alpha), which is a central regulator of the global response to hypoxia. Hepatocyte cell signaling is an important factor in hepatic fibrogenesis. We here hypothesize that HIF-1 alpha knockout in hepatocyte may protect against liver fibrosis. We first found that HFD led to 80% more hepatic collagen deposition than Hif1a(-/-)hep mice, which was confirmed by a-SMA staining of liver tissue. Body weight and liver weight were similar between groups. We then found the increasing HIF1a expression and decreasing PTEN expression in the mice on HFD and in PA-treated HepG2 cells. Finally, we found that HIF1 mediated PTEN/nfkb-p65 pathway plays an important role in the development of NAFLD to liver fibrosis. Collectively, these results identify a novel HIF1a/PTEN/NF-kappa Bp65 signaling pathway in NAFLD, which could be targeted for the therapy.