Super-resolution microscopy reveals the reorganization of GLUT4 on plasma membrane regulated by insulin resistance

Abstract

GLUT4 is essential for glucose uptake in skeletal muscles and adipocytes, which play central roles in whole-body glucose metabolism. Here, using direct stochastic optical reconstruction microscopy (dSTORM) to investigate the characteristics of the plasma membrane (PM) fused GLUT4 at the single-molecule level, we demonstrated that insulin and insulin resistance regulated the spatial organization of GLUT4 in adipocytes. Stimulation of insulin shifted the balance of GLUT4 on the PM toward a more dispersed configuration. In contrast, insulin resistance induced a more clustered distribution of GLUT4 and increased the average number of molecules per cluster. Furthermore, our data demonstrated that the F5QQI motif and lipid rafts mediated the maintenance of GLUT4 clusters on the PM. Mutation of F5QQI (F5QQA-GLUT4) induced a more clustered distribution of GLUT4; moreover, destruction of lipid rafts in adipocytes expressing F5QQA-GLUT4 dramatically decreased the percentages of large clusters and the average number of molecules per cluster. In conclusion, our data clarified the effects of insulin stimulation or insulin resistance on GLUT4 reorganization on the PM and revealed novel pathogenic mechanisms of insulin resistance.