The Effect And Mechanism Of Prmt1Expression On Glucose Toxicity-induced Ins-1Cell Dysfunction

Objective: To discuss the mechanisms of activity and expression ofPRMT1on glucose toxicity-induced β-cell dysfunction.Methods: Liposome-mediated gene transfection was used to transfersiPRMT1and pALTER-FOXO1plasmid which causes FOXO1toover-express into INS-1cells. Then, the cells were cultured in5.6mmol/Land25mmol/L glucose media with or without AMI-1（100μM）.After48hculture, total expression of PRMT1, arginine methylated protein（α-metR）,FOXO1and PDX-1, intracellular translocation of PDX-1andFOXO1were measured by western blot. Glucose Stimulated InsulinSecretion (GSIS) was measured by radioimmunoassay. Intracellular Ca2+were detected by Fura-2AM. Intracellular cAMP were measured byELISA.Result: Using INS-1cells we found that chronic exposure to highglucose increased basal insulin secretion, impaired GSIS, decreasedinsulin content, increased intracellular Ca2+and cAMP, accompaniedwith increased PRMT1expression as well as arginine methylated protein, and decreased PDX-1expression. Then inhibition of PRMT1improvedGSIS and increased insulin content through regulating PDX-1and FOXO1intracellular translocation accompanied with decreased argininemethylated protein and decreased intracellular Ca2+and cAMP. Transientoverexpression of a constitutively active FOXO1, reversed AMI-1inducedincrease of insulin content and improvement of GSIS by decreasing importof PDX-1from cytoplasm to nucleus through exclusive nuclearlocalization of FOXO1, increasing intracellular Ca2+and cAMP withoutchanges of arginine methylatation.Conclusion: PRMT1is one of the regulators of INS-1cell function,and the mechanism may be related to enhanced methylation activity-induced-increased location of FOXO1in nucleus which lead to suppresslocation of PDX-1in nucleus, so that,increasing intracellular Ca2+andcAMP, imparing insulin synthesis and GSIS.