Expression Of Spexin In Human Tissues And Its Role And Mechanism In Insulin Resistance

Objective: To investigate the expression and distribution of spexin peptide in human normal tissues.To investigate the relationship between spexin and IR,and to investigate the effect of spexin on gluconeogenesis in hepatic IR state,and to explore the possible mechanism of spexin on the regulation of gluconeogenesis pathway.Methods: The expression of spexin in normal human tissues were evaluated by traditional RT-PCR,q RT-PCR,immunohistochemistry and immunofluorescence.Serum Spexin levels were measured in T2 DM and control group,and their relationship with blood glucose,lipid,fasting insulin level and HOMA-IR were observed.SD rat model of IR induced by high-fat-diet was established.The changes of body weight,blood glucose,fasting insulin level,and HOMA-IR were observed after intraperitoneal injection of exogenous spexin for 8 weeks.We also observed the effect of spexin on GIR,GRd,and HGP by extended hyperinsulinemic-euglycemic clamp in SD rats.IR cell model of Hep G2-IR was establishmented.Different concentrations of spexin stimulated Hep G2-IR cells and the changes of glucose concentration in the culture was observed.Spexin gene was knocked out and the changes of glucose concentration in culture were observed.Expression of transcription factors(Fox O1 and PGC-1α)and key enzymes(G-6-Pase and PEPCK)of gluconeogenesis pathway were observed in vitro and in vivo.Results: The high expression of spexin was found in most endocrine tissues.Spexin was also highly expressed in the epithelial cells of human important organs and tissues.Spexin was mainly located in the cytoplasm of cell.The serum spexin level negatively correlated with blood glucose,lipid and HOMA-IR.Body weight,fasting insulin level and HOMA-IR of SD rats in the HFD group was significantly reduced after intraperitoneal injection of spexin.GIR significantly increased and hepatic glucose output inhibited in the HFD + spexin group.Spexin inhibited Hep G2-IR cell gluconeogenesis in a dose and time dependent way.The gluconeogenesis of Hep G2 with spexin gene knocking out was increased.Spexin improved hepatic steatosisthe in high-fat-diet induced IR rats.Spexin not only inhibited the expression of Fox O1,PGC-1α,PEPCK,G-6-Pase,but also increased the expression of p-Fox O1 Ser256,suggesting that Fox O1 inactivation increased in vitro and in vivo.Conclusion: Spexin was widely distributed in the human normal tissues,especially in the endocrine tissues and epithelial cells of organs and tissues.Spexin was mainly localized in the cytoplasm.Serum Spexin level was negatively correlated with blood glucose,lipid and HOMA-IR.Exogenous spexin intervention significantly reduced the body weight,fasting insulin level and HOMA-IR in high-fat-diet induced IR rats.Clamp experiment showed spexin significantly improved IR in HFD rats,and hepatic glucose output was inhibited.Spexin can be dose and time dependently inhibit gluconeogenesis of Hep G2-IR cell.Gluconeogenesis was increased in Hep G2 cell with spexin gene knocking down.Spexin inhibited the Fox O1/ PGC-1 mediated pathway and regulated gluconeogenesis.