MicroRNA-24 promotes pancreatic beta cells toward dedifferentiation to avoid endoplasmic reticulum stress-induced apoptosis

摘要

Current research indicates that beta cell loss in type 2 diabetes may be attributed to beta cell dedifferentiation rather than apoptosis;however,the mechanisms by which this occurs remain poorly understood.Our previous study demonstrated that elevation of microRNA-24(miR-24)in a diabetic setting caused beta cell dysfunction and replicative deficiency.In this study,we focused on the role of miR-24 in beta cell apoptosis and dedifferentiation under endoplasmic reticulum(ER)stress conditions.We found that miR-24 overabundance protected beta cells from thapsigargin-induced apoptosis at the cost of accelerating the impairment of glucosestimulated insulin secretion(GSIS)and enhancing the presence of dedifferentiation markers.Ingenuity?Pathway Analysis(IPA)revealed that elevation of miR-24 had an inhibitory effect on XBP1 and ATF4,which are downstream effectors of two key branches of ER stress,by inhibiting its direct target,Irela.Notably,elevated miR-24 initiated another pathway that targeted Mafa and decreased GSIS function in surviving beta cells,thus guiding their dedifferentiation under ER stress conditions.Our results demonstrated that the elevated miR-24,to the utmost extent,preserves beta cell mass by inhibiting apoptosis and inducing dedifFerentiation.This study not only provides a novel mechanism by which miR-24 dominates beta cell turnover under persistent metabolic stress but also offers a therapeutic consideration for treating diabetes by inducing dedifferentiated beta cells to re-differentiation.