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

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

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.

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).

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.