Proteomic analysis of adipocyte insulin resistance

Insulin resistance is a major risk factor for human metabolic diseases including type 2 diabetes, cardiovascular diseases and some cancers. We analysed the proteome analyses across in vitro and in vivo models of insulin resistance to find common features of insulin resistance and identified lower expression of enzymes within the mevalonate pathway. mitochondrial CoQ was lower in all models of insulin resistance. Specifically, the coenzyme Q (CoQ) biosynthetic proteins Coq 7 and 9 were decreased in adipose tissue from a mouse model of diet-induced obesity, and mitochondrial CoQ was lower in all models of insulin resistance. Moreover, the mitochondrial content of CoQ in adipose tissue correlated positively with insulin sensitivity in obese humans. Inhibition of CoQ biosynthesis induced insulin resistance, while replenishment of CoQ restored insulin sensitivity in cell culture models and in animals, demonstrating that loss of CoQ is both necessary and sufficient for adipocyte insulin resistance. Mechanistically, loss of CoQ increased mitochondrial peroxides. These findings place defective mitochondrial CoQ homeostasis upstream of increased mitochondrial oxidants in the induction of insulin resistance in adipocytes and highlight the CoQ biosynthetic pathway as an appealing therapeutic target to combat insulin resistance.