Study On The Effect Of Protein Kinase B On Perfluorooctane Sulfonate-induced Insulin Resistance

Objective: Perfluorooctane sulfonate(PFOS),one kind of persistent organic pollutants,is blamed to be associated with the incidence of insulin resistance in general human population.In our previous studies,we reported that PFOS stimulated autophagy in human liver Hep G2 cells.Autophagy stimulator rapamycin causes insulin resistance in mice fed with either low fat or high fat diets via disruption of mammalian target of rapamycin complex 2(m TORC2)signaling.m TORC2 regulates the phosphorylation of protein kinase B(AKT),and influences the expression of its downstream target genes such as phosphoenolpyruvate carboxykinase(PEPCK),leads to decreased insulin sensitivity eventually.Hepatic lipids could also impair AKT activity,through activating protein kinase C?(PKC?).Therefore,the purpose of this study was to investigate the effect and underlying mechanism of AKT in PFOS-induced insulin resistance.Methods: Human hepatoma cell line Hep G2 was selected as the test system.The cell viability was evaluated with MTT assay and lactate dehydrogenase(LDH)release test.The insulin sensitivity was evaluated by insulin-stimulated glucose uptake in cells.The triglyceride contents were detected with oil red O staining.The level of AKT,p-AKT and m TORC2 was evaluated by Western blot and immunofluorescence staining.The relative level of PEPCK m RNA,the AKT target gene,was determined by RT-q PCR.Results: The cell viability was decreased significantly after treatment with 250 ?M-300 ?M PFOS for 24 h.After treatment with 100 ?M-200 ?M PFOS for 24 h,insulin-stimulated glucose uptake was significantly decreased in a dose-dependent manner.The triglyceride contents were increased significantly in Hep G2 cells after treatment with 100 ?M-200 ?M PFOS for 24 h.After treatment with 100 ?M-200 ?M PFOS for 24 h,the levels of AKT,p-AKT and m TORC2 were decreased significantly in Hep G2 cells.After treatment with 100 ?M-200 ?M PFOS for 24 h,the levels of PEPCK m RNA were significantly increased in a dose-dependent manner in Hep G2 cells.Conclusion: The AKT phosphorylation may mediates PFOS-induced hepatic insulin resistance.