LincRNA-ROR/miR-145/ZEB2 regulates liver fibrosis by modulating HERC5-mediated p53 ISGylation.

The tumor suppressor p53 has been implicated in the pathogenesis of liver fibrosis. HERC5-mediated posttranslational ISG modification of the p53 protein is critical for controlling its activity. Here, we demonstrated that the expression of HERC5 and ISG15 is highly elevated, whereas p53 is downregulated, in fibrotic liver tissues of mice and transforming growth factor-ß1 (TGF-ß1)-induced LX2 cells. HERC5 siRNA clearly increased the protein expression of p53, but the mRNA expression of p53 was not obviously changed. The inhibition of lincRNA-ROR (ROR) downregulated HERC5 expression and elevated p53 expression in TGF-ß1-stimulated LX-2 cells. Furthermore, the expression of p53 was almost unchanged after TGF-ß1-stimulated LX-2 cells were co-transfected with a ROR-expressing plasmid and HERC5 siRNA. We further confirmed that miR-145 is a target gene of ROR. In addition, we also showed that ROR regulates the HERC5-mediated ISGylation of p53 through mir-145/ZEB2. Together, we propose that ROR/miR-145/ZEB2 might be involved in the course of liver fibrosis by regulating ISGylation of the p53 protein.

Hif-2α regulates lipid metabolism in alcoholic fatty liver disease through mitophagy.

BACKGROUND: Disordered lipid metabolism plays an essential role in both the initiation and progression of alcoholic fatty liver disease (AFLD), and fatty acid ß-oxidation is increasingly considered as a crucial factor for controlling lipid metabolism. Hif-2α is a member of the Hif family of nuclear receptors, which take part in regulating hepatic fatty acid ß-oxidation. However, its functional role in AFLD and the underlying mechanisms remain unclear. RESULTS: Hif-2α was upregulated in EtOH-fed mice and EtOH-treated AML-12 cells. Inhibition or silencing of Hif-2α led to increased fatty acid ß-oxidation and BNIP3-dependent mitophagy. Downregulation of Hif-2α activates the PPAR-α/PGC-1α signaling pathway, which is involved in hepatic fatty acid ß-oxidation, by mediating BNIP3-dependent mitophagy, ultimately delaying the progression of AFLD. CONCLUSIONS: Hif-2α induces liver steatosis, which promotes the progression of AFLD. Here, we have described a novel Hif-2α-BNIP3-dependent mitophagy regulatory pathway interconnected with EtOH-induced lipid accumulation, which could be a potential therapeutic target for the prevention and treatment of AFLD.

Bmal1 inhibits phenotypic transformation of hepatic stellate cells in liver fibrosis via IDH1/α-KG-mediated glycolysis.

Hepatic stellate cells (HSCs) play an important role in the initiation and development of liver fibrogenesis, and abnormal glucose metabolism is increasingly being considered a crucial factor controlling phenotypic transformation in HSCs. However, the role of the factors affecting glycolysis in HSCs in the experimental models of liver fibrosis has not been completely elucidated. In this study, we showed that glycolysis was significantly enhanced, while the expression of brain and muscle arnt-like protein-1 (Bmal1) was downregulated in fibrotic liver tissues of mice, primary HSCs, and transforming growth factor-ß1 (TGF-ß1)-induced LX2 cells. Overexpression of Bmal1 in TGF-ß1-induced LX2 cells blocked glycolysis and inhibited the proliferation and phenotypic transformation of activated HSCs. We further confirmed the protective effect of Bmal1 in liver fibrosis by overexpressing Bmal1 from hepatic adeno-associated virus 8 in mice. In addition, we also showed that the regulation of glycolysis by Bmal1 is mediated by the isocitrate dehydrogenase 1/α-ketoglutarate (IDH1/α-KG) pathway. Collectively, our results indicated that a novel Bmal1-IDH1/α-KG axis may be involved in regulating glycolysis of activated HSCs and might hence be used as a therapeutic target for alleviating liver fibrosis.