The Role And Mechanism Of S100A11 In The Development Of Nonalcoholic Fatty Liver Disease (NAFLD)

Background Non-alcoholic fatty liver disease(NAFLD)is one of the most common chronic liver diseases worldwide,which ranges from non-alcoholic fatty liver(NAFL)to non-alcoholic steatohepatitis(NASH),cirrhosis,and hepatocellular carcinoma.S100A11 is a multifunctional protein that previously reported as a poor prognostic indicator of hepatocellular carcinoma,while the role of S100A11 affects NAFLD is still not clear.Therefore,in this study,we intended to analyze the role of S100A11 in the development of NAFLD and explored its potential mechanism.Materials and methods 1.A variety of non-alcoholic fatty liver disease(NAFLD)models were established to detect the mRNA expressions of S100A11 to explain the relationship between S100A11 and hepatic lipid metabolism.2.We established the S100A11 over-expressed/knocked-down cell line in the AML 12 cell to explore the expression of genes involved in hepatic lipid metabolism and determine the triglyceride(TG)level.3.S100A11 liver-specific over-expressing mice were established by adeno-associated virus-8(AAV-8)to measure the insulin sensitivity and explore the expression of genes involved in hepatic lipid metabolism.The TG level and the metabolic injury markers were explicitly detected by the corresponding kits.Hepatic pathological changes were observed by H&E staining and ORO.4.Western blotting technology was used to identify the molecular mechanism of S100A11 involved in hepatic-specific lipid metabolism regulation in vitro and in vivo.5.Knockdown the Receptor of Advanced Glycation End Products(RAGE)and over-expressing S100A11 at the same time in AML 12 cell lines to detect the level of lipid metabolism genes and measure the TG content in intro or in vivo.The level of S100A11 and its downstream signaling molecules were detected by Western blotting.Results 1.The mRNA and protein level of S100A11 was increased in different non-alcoholic fatty liver disease(NAFLD)models.2.Overexpressing S100A11 in AML 12 cell lines improved lipid metabolism and aggraved lipid deposition.While knocking down the level of S100A11 leads to the down-regulated of lipid metabolism-related genes and decreased lipid deposition.3.Up-regulation of hepatic S100A11 expression in C57BL/6 mice can accelerate insulin resistance,liver function injury and promote the expression of lipid metabolism-related genes.The results of H&E staining and ORO showed that S100A11 could increase hepatic lipid deposition.4.S100A11 can induce lipid synthesis and aggravate lipid deposition in vivo and in vitro by activating the AKT/mTORC1/SREBP1c signaling pathway axis through binding to RAGE.Conclusion 1.As a secreted protein,S100A11 is significantly increased in NAFLD models,suggesting that S100A11 may become a new biomarker for obesity and NAFLD;2.Overexpression of S100A11 in AML12 cell line in vitro leads to the upregulation of lipid metabolism-related genes,leading to increased liver lipid deposition.In contrast,knockdown of S100A11 leads to the downregulation of lipid metabolism-related genes and improved lipid deposition.Liver S100A11 overexpression in C57BL/6 mice increased insulin resistance,the expression of genes involved in lipid metabolism,and liver damage markers in serum,suggesting that S100A11 is directly involved in the process of liver gluconeogenesis,lipid metabolism and inflammation;3.S100A11,as a multi-biological calcium ion binding protein,promotes the activation of the AKT-mTORC1 signal by binding to receptor for advanced glycation end products(RAGE),which increase SREBP1c activity and induce fatty acid synthesis,leading to fatty liver.