Mechanism Of STING Regulating Lipid Metabolism In Fatty Liver Hepatocytes

Fatty liver disease is a common chronic metabolic disorder in dairy cows,with approximately 50% of high-yielding cows experiencing varying degrees of fatty liver during the peripartum period,which has a significant impact on the development of the livestock industry.Studies have shown that the development of fatty liver disease in dairy cows is related to the special metabolic state during the peripartum period,but the exact pathogenesis of fatty liver disease in dairy cows is still unclear.Stimulator of interferon genes(STING)is an endoplasmic reticulum transmembrane protein,and recent studies have shown that STING is involved in innate immune and anti-tumor responses,as well as playing an important role in lipid metabolism,which may be related to lipid deposition in the liver.To investigate the role and impact of STING in the development of fatty liver disease in dairy cows,this experiment successfully constructed models of STING protein activation and inhibition by activating and inhibiting STING protein activity.The impact of changes in STING protein activity on intracellular lipid deposition was detected using oil red O staining.The impact of STING activity on metabolism in primary liver cells of dairy cows was analyzed using transcriptomics.STING gene knockdown or overexpression models were constructed in NCTC1469 mouse liver cell lines using a lentiviral vector,and then a mouse fatty liver cell model was induced to verify the effect of STING gene in mouse liver cells on intracellular lipid deposition.To investigate the role and mechanism of STING in the pathogenesis of bovine hepatic lipidosis,this study constructed models of STING protein activation and inhibition through drug activation and inhibition of STING protein activity.The impact of changes in STING protein activity on intracellular lipid deposition was assessed using Oil Red O staining.Transcriptomic analysis was employed to evaluate the effects of STING activity on the metabolism of primary bovine liver cells.Lentiviral vectors were constructed to knockdown or overexpress STING in the mouse liver cell line NCTC1469,and a mouse fatty liver cell model was established to verify the effects of STING gene on intracellular lipid deposition in mouse liver cells.(1)In this experiment,we successfully induced both bovine and mouse fatty liver cell models using sodium oleate(OA).By using the inhibitor C176 and the activator di ABZI,we also successfully constructed bovine primary liver cell models with STING protein inhibition and activation,respectively.Furthermore,we constructed mouse models with STING gene overexpression and knockdown using a lentivirus vector and selected stable cell lines.(2)To investigate the effects of STING protein inhibition and activation on lipid deposition in primary bovine liver cells,this experiment was conducted with different treatment groups(D group: di ABZI + OA;C group: C176 + OA;OA group)and a control group.Oil red O staining showed that inhibiting STING protein activity can reduce lipid accumulation in liver cells,while activating STING has the opposite effect.Gene differential expression analysis revealed that in the OA and control groups,differentially expressed genes were mainly enriched in lipid metabolism-related pathways such as "lipid biosynthesis" and "cholesterol biosynthesis".Changes in gene expression levels such as ACACA,ACOT1,ACOT2,and ANGPTL4 affected cell lipid biosynthesis,cholesterol metabolism,and PPAR signaling pathways,leading to disrupted lipid metabolism and promoting the formation of fatty liver.In the D group and OA group,and the D group and control group,when STING was activated,in addition to causing innate immune responses in cells,it also affected lipid metabolism by influencing genes such as ABCB11,ABCG1,and FABP1.Significant upregulation of genes such as BNIP3,ATF4,and COX4Ⅰ1 indicated that activating STING protein activity may lead to endoplasmic reticulum stress and mitochondrial metabolism disorders.Downregulation of genes such as IDH,LANCL1,and IDPc indicated that increasing STING protein activity with drugs may affect glutathione metabolism and exacerbate mitochondrial damage.(3)To further determine the effect of STING on hepatic lipid accumulation,STING knockdown and overexpression cell lines were used to induce a model of fatty liver,and the changes in lipid droplet-related protein ADRP were detected.The results showed that under STING knockdown,with the induction of fatty liver,the expression of ADRP in the cells decreased significantly compared to the control group(P < 0.05);under STING overexpression,the expression of ADRP in the cells significantly increased compared to the control group(P <0.05),indicating that the STING gene plays an important role in hepatic lipid accumulation.In summary,STING has a discernible impact on the formation of fatty liver,and inhibiting STING protein activity(or knocking down the STING gene)can slow down lipid accumulation in liver cells.This may be achieved by altering cell antioxidant capacity,folate metabolism,endoplasmic reticulum stress,and mitochondrial dysfunction,thereby affecting the regulation of lipid metabolism.