miR-122 promotes hepatic lipogenesis via inhibiting the LKB1/AMPK pathway by targeting Sirt1 in non-alcoholic fatty liver disease

Abstract

Background Non-alcoholic fatty liver disease (NAFLD) is a common hepatic disease with an increasing prevalence but an unclear aetiology. This study aimed to investigate the functional implications of microRNA-122 (miR-122) in the pathogenesis of NAFLD and the possible molecular mechanisms. Methods Both in vitro and in vivo models of NAFLD were generated by treating HepG2 and Huh-7 cells with free fatty acids (FFA) and by feeding mice a high-fat diet (HFD), respectively. HE and Oil Red O staining were used to examine liver tissue morphology and lipid deposition, respectively. Immunohistochemical (IHC) staining was used to examine Sirt1 expression in liver tissues. qRT-PCR and Western blotting were employed to measure the expression of miR-122, Sirt1, and proteins involved in lipogenesis and the AMPK pathway. Enzyme-linked immunosorbent assay (ELISA) was used to quantify triglyceride (TG) levels in HepG2 and Huh-7 cells and in liver tissues. The interaction between miR-122 and the Sirt1 gene was further examined by a dual luciferase reporter assay and RNA-immunoprecipitation (RIP). Results NAFLD hepatic tissues and FFA-treated HepG2 and Huh-7 cells presented excess lipid production and TG secretion, accompanied by miR-122 upregulation, Sirt1 downregulation, and potentiated lipogenesis-related genes. miR-122 suppressed Sirt1 expression via binding to its 3′-untranslated region (UTR). Knockdown of miR-122 effectively mitigated excessive lipid production and suppressed the expression of lipogenic genes in FFA-treated HepG2 and Huh-7 cells via upregulating Sirt1. Furthermore, miR-122 knockdown activated the LKB1/AMPK signalling pathway. Conclusion The inhibition of miR-122 protects hepatocytes from lipid metabolic disorders such as NAFLD and suppresses lipogenesis via elevating Sirt1 and activating the AMPK pathway. These data support miR-122 as a promising biomarker and drug target for NAFLD.

Mechanisms of Non-Alcoholic Fatty Liver Disease in the Metabolic Syndrome. A Narrative Review

“…miR-122 seems also responsive to diet in both in vitro and in vivo models and in humans. In particular, miR-122 appears upregulated in the presence of a high-fat diet, thus resulting in the promotion of lipogenesis in the liver [ 162 ].…”

Nutrition and Genetics in NAFLD: The Perfect Binomium

“…In contrast, Long et al found that FFAs or HFD upregulated miR-122 in hepatocytes-derived HepG2 and HuH7 cell lines and in mice, respectively, revealing that miR-122 may promote lipogenesis by suppressing Sirt1. Indeed, miR-122 knockdown mitigated hepatic steatosis via Sirt1-induced liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) pathway [131].…”

The Prediction of Survival in Hepatocellular Carcinoma Based on A Four Long Non-coding RNAs Expression Signature

“…In our study, a similar association between the expression level of DGCR9 and HCC patient OS was also observed, though our study included patients with HBV either positive or negative. Furthermore, in the network analysis (Figure 5a and Figure 5b), we showed that DGCR9 (ENSG00000273032) might act as a ceRNA to intervene in HCC pathogenesis by competitively associated to miR-122 and miR-885, which have been found to be involved in liver diseases or liver cancer [45][46][47]. All these results call for further studies to conclude a causal association between these relationships, which may contribute to novel targeted therapy.…”