Insulin Resistance and Gender Define a Cell Autonomous Supernetworkof Protein Phosphorylation

Abstract

Many hormones and growth factors, including insulin, act through networks of protein phosphorylation. Insulin resistance is an important factor in the pathophysiology of many metabolic disorders. The aim of this study was to uncover the cell autonomous determinants of insulin action and protein phosphorylation using induced pluripotent stem cell (iPSC)-derived myoblasts (iMyos) in vitro. Here, we show that iMyos from non-diabetic individuals in the highest quintile of insulin resistance show impaired insulin signaling, defective insulin-stimulated glucose uptake and decreased glycogen synthase activity compared to iMyos from the insulin sensitive individuals, indicating these cells mirror in vitro the alterations seen in vivo. Global phosphoproteomic analysis uncovered a large network of proteins whose phosphorylation was altered in association with insulin resistance, most outside the canonical insulin-signaling cascade. More surprisingly, we also observed striking differences in the phosphoproteomic signature of iMyos derived from male versus female subjects, involving multiple pathways regulating diverse cellular functions, including DNA and RNA processing, GTPase signaling, and SUMOylation/ubiquitination. These findings provide new insights into the cell autonomous mechanisms underlying insulin resistance in the non-diabetic population and provide evidence of a major, previously unrecognized, supernetwork of cell signaling differences in males and females that must be considered in understanding the molecular basis of sex-based differences in normal physiology and disease.