PNPLA3基因在非酒精性脂肪性肝病中的作用

Roles of Autophagy and Protein Kinase C-epsilon in Lipid Metabolism of Nonalcoholic Fatty Liver Cell Models

OBJECTIVE

To investigate interaction between autophagy and PKC-ε in lipid metabolism of NAFLD cell models.

METHODS

HL-7702 cells and SK-HEP-1 cells were cultured in vitro as NAFLD cell models and treated with RAPA to induce autophagy. 3-MA was used to inhibit cell autophagy. And HL-7702 and SK-HEP-1 cell were ordinary cultured as control groups. Cell viability was determined by MTT colorimetric assay. The levels of TG, TC and PKC-ε were detected by ELISA. PKC-ε was detected by IF. LC3-II/LC3-I, P62, IRS-1, IRS-2, PI3Kp85, mTOR were detected by Western-blot. SPSS 20 software was used for statistical analysis.

RESULTS

The values of PKC-ε were the highest in the steatosis groups (HL-7702 cells were 91.10%, SK-HEP-1 cells were 98.20%). Compared with the steatosis groups, the LC3-II/LC3-I ratio in the induced autophagy groups increased obviously (p <0.05). P62/β-actin grayscale ratio of the induced autophagy groups decreased significantly compared with the steatosis group (p <0.05). MTOR/β-actin grayscale ratio in the induced autophagy groups were significantly lower than those in the steatosis groups (p <0.05). PI3Kp85, IRS-1 and IRS-2/β-actin grayscale ratio of the induced autophagy groups increased significantly compared with the steatosis group (p <0.05).

CONCLUSION

Up-regulation of autophagy can promote the elimination of liver fat; while down-regulation can promote lipid accumulation. The expression of PKC-ε is positively related to the degree of hepatic steatosis. PI3K was involved in both autophagy and IR induced by PKC-ε. PKC-ε might participate in hepatocyte autophagy by regulating PI3K.

Role of ChREBP and its target gene PNPLA3 in pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a clinical and pathological syndrome caused by excessive triglyceride accumulation in liver cells. Its hepatic histological changes are similar to those of alcoholic liver disease (ALD), but the patients do not have a history of heavy alcohol drinking. NAFLD includes nonalcoholic simple fatty liver (NASFL), nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty hepatitis related to liver fibrosis and cirrhosis. At present, the detailed pathogenesis of NAFLD is unclear. Many studies have reported the relationship between ChREBP and its target gene PNPLA3 and NAFLD occurrence. ChREBP and PNPLA3 are associated with liver fat content and inflammation. This article reviews the role of ChREBP and its target gene PNPLA3 in the pathogenesis of NAFLD, in order to provide a theoretical basis for further research of the occurrence and treatment of NAFLD.

Role of PNPLA3 polymorphism in pathogenesis of liver diseases

Hepatic fat accumulation, a common phenomenon in nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD), is associated with liver inflammation development and disease progression. Besides, hepatic fat accumulation is also seen in HCV-infected patients, which influences the response to anti-HCV therapy. Although the causes of fatty accumulation in the above three diseases are different, hereditary factors causing fatty accumulation have attracted more and more attention. PNPLA3, a member of patatin-like phospholipase family, has the activity of triglyceride hydrolase and can influence the liver fatty metabolism. In recent years, PNPLA3 polymorphism has become a hot topic in research of NAFLD, ALD, and HCV, and important results have been achieved. This article describes the expression of PNPLA3 in human tissues and review recent progress in understanding the role of PNPLA3 polymorphism in the pathogenesis of the above three liver diseases.