To identify disease-specific indicators associated with insulin resistance by using human induced pluripotent stem cells (iPSCs) as a “disease-in-a-dish” model, iPSCs were derived from 20 nondiabetic individuals, with 10 each in the most insulin resistant (IR) or insulin sensitive (IS) quintiles as determined using SSPG measurements. Half of each group was male and half female. Given that muscle is the first site of insulin resistance in type 2 diabetes, iPSCs were differentiated into myoblasts, and global phosphoproteomics was performed without/with insulin stimulation to determine the full spectrum of signaling. Analysis of phosphoproteome revealed altered serine/threonine phosphorylation of the insulin-regulated sites on IRS2, Akt1, mTOR, RPS6 in the IR iPSC-myoblasts indicating defects related to insulin resistance. Unexpectedly, hierarchical clustering of the phosphosites (FDR< 0.05) also revealed alterations in IR males as compared to IS males but not in females. Rather female cells demonstrated a drastically different overall phosphoproteome as compared to the males, indicating the existence of an important sexual dimorphism that dominated over differences in insulin resistance. The top up-regulated phosphosites in the males, such as SRRM1 S697, THRAP3 S535, PRRC2C T1244 (all p<1x10-9 and fold change >5 compared to females) belonged to mRNA splicing pathway and included many targets of mTOR. In contrast, some of the top up-regulated phosphosites in the females included LMNB1 S23, SKP2 S64, MARCKS S167 (p<1x10-7 and fold change >5 compared to males) belonged to cell cycle pathways. These findings indicate that iPSC-derived myoblasts provide a potent approach to understanding differences in phosphorylation networks. These studies have also uncovered previously unrecognized differences in signaling between males and females, which may play a major role in the pathogenesis of disease.
N. Haider: None. J. Lebastchi: None. T.M. Batista: None. J. Knowles: None. H. Pan: None. J. Dreyfuss: None. C. Kahn: Advisory Panel; Self; ERX Pharmaceuticals, Kaleido Biosciences. Consultant; Self; AntriaBio, Flagship Pioneering, Sana-Cobalt.