Identification And Functional Study Of Rab31 As An Interactor Of RAGE In AGEs-induced Pancreatic ?-cell Apoptosis

Diabetes mellitus(DM)is a group of metabolic disorders characterized by hyperglycemia over a prolonged period.The high blood glucose level may result in the non-enzymatic glycation between d-glucose and various proteins or lipids and finally form the Advanced glycation end-products(AGEs).Many studies have revealed that AGEs play a pivotal role in chronic complication.Our previous studies show that after interacting with RAGE(Receptor for AGEs),AGEs contribute to ?-cell apoptosis through mitochondria mediated endogenous signal pathway.According to previous studies and biological analysis,the cytoplasmic tail of RAGE interacts with its interator,which can regulate the signal transduction of AGEs.However,the mechanism has not yet been reported.In this study,we searched the RAGE-interaction proteins by GST-pull down.First,we constructed a prokaryotic expression plasmid of pGEX-4T-CR43 and successfully expressed it in E.coli.Then,we identified a small GTP-binding protein named Rab31 by GST-pull down and mass spectrometry,which was a novel interaction protein of CR43.We confirmed that the cytoplasmic tail of RAGE interacts with Rab31 after the treatment of GS by Co-IP assays and co-immunofluorescence staining.We further discovered that silencing Rab31 reduced the internalization of RAGE induced by GS and increased the protein level of RAGE.These results indicate that Rab31 regulates the endocysis,trafficking and degradation of RAGE.Consistant with this,knockdown of Rab31 aggravates the GS-induced apoptosis of pancreatic ? cells,while overexpression of Rab31 partially ameliorates the impairment of ? cells by GS,which means Rab31 can inhibit the pro-apoptostic effect of AGEs-RAGE axis.In conclusion,our study first reveals that Rab31 is an interacting protein of the cytoplasmic tail of RAGE and negtively regulates the pro-apoptostic effect of AGEs on pancreatic ? cells,which partially protect pancreatic Pcells from damage induced by AGEs.The study reveals the underlying mechanism in which AGEs-induced impairment to pancreatic beta cells could be attenuated,and provides the new insight for prevention and treatment of diabetes.