The Role Of Poldip2 In Insulin Signal Pathway And Regulation Of Lipid Metabolism Associated With Type 2 Diabetes Mellitus

Objective: This study was designed to investigate the role of Poldip2 in the insulinsignaling pathway and the regulation of lipid metabolism in KKAy mice.Methods:（1）Mc Ardle 7777 cells were incubated with high glucose and normal glucose respectively to detected TG and TCH levels and Poldip2 expression under high glucose and normal glucose.（2）Establish the insulin resistance by insulin,to detect the dose-response relationship and the time-effect relationship of Poldip2 under the action of insulin,and the lipid metabolism of Poldip2 to Mc Ardle 7777 cells at the optimal insulindosage and time.（3）In vivo,KKAy mice were randomly divided into Poldip2 virus group,GFP group and Saline group after 4 weeks high-fat diet.In addition,C57 BL / 6J mice were used as control groups.The serum levels of free fatty acids,insulin,leptin,liver lipid,hepatic PTP1 B enzyme activity and H₂O₂ level were measured.The expression of related protein in insulin signaling pathway was also detected.Results: In cell experiments,the expression of Poldip2 was significantly decreased in high glucose,and high glucose decreased the lipid metabolism.In the insulin stimulation test,cell under the normal glucose,the insulin dose was 20μmol,the cell incubation time was 24 h,the expression of Poldip2 protein was the most abundant.Under the high glucose,the insulin dosage was 5μmol,and Poldip2 expression was the most abundant after 6h,the TCH level was significantly higher than cell in high glucose without insulin stimulated.It was also found that lower doses of insulin in high glucose culture could inhibited the expression of Poldip2.In vivo animal experiments,Poldip2 adenovirus can significantly improve blood glucose levels in KKAy mice,and can reduce serum TG,TCH,l DL-C and liver TCH levels;reduce serum levels of free fatty acids and insulin levels.Poldip2 could increase the level of H₂O₂ and decrease the activity of PTP1 B enzyme in the fresh liver.It was found that Poldip2 could accelerate the metabolism of fat in mice by the postprandial lipid tolerance test.Poldip2 could decrease the expression of PTEN and PTP1 B protein in KKAy mice,and activate the activity of Akt to promote the insulin signal pathway.In addition,Poldip2 may reduce the expression of PEPCK protein,thereby inhibiting the synthesis of gluconeogenesis,so that the liver glucose output decreased.Conclusion: Cells were found to be highly toxic in high glucose cultures,resulting in lipid metabolism disorders,which may be associated with decreased levels of Poldip2 protein in cells under high glucose culture.Poldip2 can reverse the abnormalities of exogenous lipid metabolism and improve the lipid metabolism of mice.The mechanism of Poldip2 to improve the metabolism of glucose and lipid in diabetic mice may be through the expression of Poldip2,activation of Nox4 to produce H₂O₂,excessive oxidation inhibited the activity of PTP1 B,PTEN,and thus activate the activity of Akt protein,Improve the insulin signal pathway,reverse the glycolipid metabolic disorders.