Study On Expression Pattern,Transcriptional Regulation And Function Of Complement C3 Gene In The Development Of Goose Fatty Liver

Goose fatty liver can be induced by overfeeding of high-energy diet,which is characterized by a large amount of fat deposited in the liver.Interestingly,goose fatty liver does not have obvious pathological changes even in the case of severe steatosis,indicating that there is a special tolerance mechanism in goose fatty liver.Revealing this tolerance mechanism may provide a new idea for improving the yield and quality of goose fatty liver.Studies have shown that complement system is highly activated during the formation of steatohepatitis in humans and rodents.The knockout of complement C3/C5 genes,the core component of complement system,can effectively alleviate hepatic steatosis and inflammation induced by alcohol or high-fat diet.On the contrary,the whole complement system in goose fatty liver is inhibited,suggesting that the complement system might be related to the tolerance mechanism of goose fatty liver.In this study,one of the core components of complement system,complement C3 gene,was investigated as follows:RT-PCR and Western blot technologies were used to determine the effect of overfeeding on the expression of complement C3 gene in energy metabolism related tissues(liver,muscle and adipose tissues)and the changes of complement C3 gene expression in liver with the time of overfeeding.Goose and mouse primary hepatocytes were isolated and cultured to study the effecs of fatty liver related factors(glucose,fatty acids and insulin)on complement C3 gene expression in the cells.To clarify the role of complement C3 gene in goose fatty liver,the overexpression vector of complement C3 gene was constructed and transfected into goose primary hepatocytes,and the differentially expressed genes after overexpression were detected by RNA-seq technology.The GO and KEGG pathways of the differentially expressed genes were analyzed to clarify the role of complement C3 gene in goose fatty liver.The main research results are as follows:1.the mRNA and protein expression levels of complement C3 gene in goose liver were significantly lower than that of control goose(P<0.05)after overfeeding for 19 days.2.compared with the control group,200 nM insulin significantly inhibited the expression of complement C3 gene in goose primary hepatocytes(P<0.05).Different concentrations(0.125 mM,0.25 mM)of oleic acid could also decrease the expression level of complement C3 gene in goose primary hepatocytes,and 0.125 mM oleic acid treatment showed a significant effect(P<0.05),which was opposite to the expression profile in mouse primary hepatocytes.However,different concentrations of glucose and palmitic acid did not cause significant changes in complement C3 gene expression in primary hepatocytes of geese and mice(P>0.05).3.RNA-seq analysis showed that 1123 differentially expressed genes were screened by comparing overexpression group with the control group,of which 557 genes were up-regulated and 566 genes were down-regulated.The GO and KEGG pathway analysis showed that the differentially expressed genes were mainly enriched in the immune/inflammatory pathway(such as Nod-like receptor signaling pathway),and glycolipid metabolism and cell death related pathways.In conclusion,the down-regulation of complement C3 gene expression in goose fatty liver may be related to hyperlipidemia and hyperinsulinemia.Complement C3 gene may participate in the formation of goose fatty liver by influencing fatty synthesis,cell growth,and signal pathways related to immune/inflammatory response,especially by inhibiting the occurrence of inflammation in fatty liver through NOD like receptor signal pathway,thus enhancing the tolerance of goose fatty liver to severe steatosis.