Molecular Mechanism And Role Of Orexin-a In Regulating Autophagy Of MIN6 Cells Through PI3K/AKT Pathway

Objective:Type 2 diabetes is caused by abnormal glucose and lipid metabolism caused by relative or absolute insulin deficiency or insulin resistance in the body.Insulin deficiency is mainly caused by reduced production,excessive destruction or functional defects of islet beta cells.At present,relevant studies have confirmed that long-term elevated blood glucose in vivo can cause oxidative stress,endoplasmic reticulum stress response and inflammatory effects on pancreatic beta cells and peripheral tissues.Autophagy is a conserved eukaryotic cell degradation process that maintains homeostasis through autophagy.Autophagy alleviates cell damage under stress by removing and recycling damaged organelles,aging organelles and useless macromolecules,and produces nutrients and energy that can be reused.Autophagy plays a dual role in regulating cell death.Mild autophagy can protect cells from damage to a certain extent,while severe autophagy can promote programmed apoptosis.Existing evidence has shown that orexin A can participate in the regulation of autophagy through autophagy-related signaling pathways.Orexin can significantly increase the secretion of insulin in the pancreas of normal and diabetic rats.Related studies confirmed that orexin A stimulated AKT signaling pathway through orexin receptor 1（OX1R）and affected the proliferation of INS cells in rats.OXA stimulates AKT signaling pathway to protect cells through OX1R,promotes the proliferation of INS cells and reduces the pro-apoptotic Caspase-3 activity.However,the relationship between orexin and autophagy of pancreatic beta cells and its molecular biological mechanism and signal transduction pathway are still unclear.In this study,the molecular pathway of orexin A regulating autophagy of MIN6 cells through PI3K/AKT signaling pathway and its specific role were discussed using MIN6 isletβcells of mice as the research object.Methods:MIN6 cells were treated with 10^-10m OXA,and the submicroscopic structure of autophagosomes in MIN6 cells was observed by transmission electron microscope.Western blot analysis was used to detect the total AKT protein and phosphorylated p-AKT protein levels the expression of autophagy related protein,LC3and Beclin.Results:1.OXA inhibited autophagy in MIN6 cells.The expression level of autophagy-related proteins in MIN6 cells treated with OXA was significantly lower than that in the control group.2.Total AKT level remained unchanged in the OXA treatment group,while phosphorylated AKT level increased,LC3-2/LC3-1 ratio expression level decreased,and Beclin expression level decreased;AKT specific inhibitor PF-04691502activates the expression of autophagy-related proteins LC3-2 and Beclin.Conclusion:Orexin-A inhibits autophagy of MIN6 cells through PI3K/AKT signal pathway,alleviates islet cell injury and slows down the occurrence and development of diabetes.