The Role Of MiR-299-5p In Pancreatic P Cell

Glucolipotoxicity is a key factor in the pathogenesis of type 2 diabetes mellitus,whose underlying molecular mechanisms have not been fully understood.Regulating gene expression in post-transcriptional level by binding to the 3'UTR of target mRNAs,miRNAs have been implicated in many biological processes,including cell differentiation,metabolism and survival.Emerging evidences suggest that miRNAs are important factors of the pathogenesis of diabetes mellitus.However,the investigation of the involvement of miRNAs in glucolipotoxicity is in its infancy.In this study,we identified a downregulated miRNA,miR-299-5p,in islets from db/db mice,GK rats as well as primary mouse and rat islets and pancreatic beta-cell lines under the attack of glucolipotoxicity.TMT(Tandem Mass Tags)labeled proteomic profiling together with IPA(Ingenuity Pathway Analysis)revealed that miR-299-5p inhibition was highly correlated to beta-cell dysfunction and apoptosis,which was later proved by us in isolated mouse and rat islets,MIN6 cells and INS-1 cells.Conversely,miR-299-5p overexpression partially restored beta-cell function damaged by glucolipotoxicity.Additionally,Perp,Siahl,Rassf6 and Sgk1 were proved to be the targets of miR-299-5p by dual-luciferase reporter assay,whose protein levels in beta cells were increased by glucolipotoxicity.Moreover,ectopic expression of Perp not only impaired beta-cell function but also markedly augmented the proapoptotic effect of glucolipotoxicity on beta cells.On the contrary,Perp deficiency partially abrogated anti-miR-299-5p-as well as glucolipotoxicity-induced beta-cell dysfunction and apoptosis.Our study first illustrates that miR-299-5p is reduced by glucolipotoxicity in beta cells,and subsequently results in beta-cell dysfunction and apoptosis,which is partly ascribed to one of its targets,Perp.These findings provide new insight into the mechanisms of glucolipotoxicity.Low-expressed as it is in beta cells,miR-299-5p is indispensable for beta-cell function and survival,which may bring the miRNAs that have long been ignored before because of their low expression levels in beta cells into our focus.