S100A16 Regulates Liver Lipid Metabolism In Mice Through The CaM/CAMKK2/AMPK Pathway

Objective: Previous studies have shown that S100 calcium binding protein A16(S100A16)is involved in the regulation of lipid metabolism in adipocytes,and the relationship between S100A16 and hepatic lipid metabolism is still unclear.This study aimed to investigate the role of S100A16 in Non-alcoholic fatty liver disease(NAFLD).Methods: A 5-week-old S100a16 transgenic mouse model(S100a16 transgenic),S100a16 knockdown mouse model(S100a16 knockdown),and Wildtype C57BL/6mice were used as experimental subjects.20 mice per genotype.Randomly divided into normal fat diet(NFD)and high fat diet(HFD),a total of 6 groups,Wildtype mice normal fat diet group(n = 10),Wildtype mice high-fat diet group(n=10),S100a16 transgenic mice normal fat diet group(n=10),S100a16 transgenic mice high fat diet group(n=10),S100a16 knockdown mice normal fat diet group(n=10),S100a16 knockdown mice high fat diet group(n=10).after 16 weeks of feeding,test the serum triglyceride(TG),total cholesterol(TC),alanine aminotransferase(ALT),aspartate aminotransferase(AST)and other biochemical indicators And the mice were sacrificed,the changes in the morphology of the liver of the mice were observed by HE and oil red O staining,NAFLD cell model with abnormal expression of S100A16 was constructed in vitro and its phenotypic changes were detected.The relationship between S100A16 and Ca M,and the expression of Ca M/CAMKK2/AMPK pathway related proteins and genes were detected by various biological methods at two levels of cell(LO2 cell)and liver tissue of mice.Results: In HFD-fed mice,S100a16 transgenic mice showed significantly more severe fatty liver and higher serum triglyceride(TG)concentrations than other genotype mice,total cholesterol(TC),Alanine aminotransferase(ALT)and aspartate aminotransferase(AST)also increased significantly;there were significantly more lipid droplets in the liver.Whereas S100a16 knockdown mice were completely opposite,compared with normal genotype mice,liver steatosis,TG,TC,ALT,AST serological changes were mild,For NFD-fed mice,liver fat accumulation and serum TG,TC,ALT,AST levels were significantly lower than those fed HFD,and no significant lipid droplets were found in the liver.The results of NAFLD cell model in vitro were consistent with those of mouse experiment.In addition,the interaction between calmodulin(Ca M)and S100A16 was observed at both liver and LO2 cell levels,and S100A16 could regulate the expression of CAMKK2,p CAMKK2,AMPK,p AMPK,SREBP1 c,ACC,p ACC,FAS,and alter the ratio of p CAMK2/CAMK2,p AMPK/AMPK,which represent the activity of Ca M/CAMK2/AMPK pathway,as well as the downstream of the pathway,the transcriptional levels of Srebp1 c,Acc and Fas genes related to lipid synthesis changed.Conclusion: S100A16 interacts with Ca M,S100A16 regulates lipid metabolism through Ca M/CAMKK2/AMPK pathway,over-expression of S100A16 promote s the deterioration of HFD-induced NAFLD in mice,while low expression of S100A16 reduces NAFLD.