A muscle-specific UBE2O/AMPK alpha 2 axis promotes insulin resistance and metabolic syndrome in obesity

초록

Ubiquitin-conjugating enzyme E2O (UBE2O) is expressed preferentially in metabolic tissues, but its role in regulating energy homeostasis has yet to be defined. Here we find that UBE2O is markedly upregulated in obese subjects with type 2 diabetes and show that whole-body disruption of Ube2o in mouse models in vivo results in improved metabolic profiles and resistance to high-fat diet-induced (HFO-induced) obesity and metabolic syndrome. With no difference in nutrient intake, Ube2o(-/-) mice were leaner and expended more energy than WT mice. In addition, hyperinsulinemic-euglycemic clamp studies revealed that Ube2o(-/-) mice were profoundly insulin sensitive. Through phenotype analysis of HFD mice with muscle-, fat-, or liver-specific knockout of Ube2o, we further identified UBE2O as an essential regulator of glucose and lipid metabolism programs in skeletal muscle, but not in adipose or liver tissue. Mechanistically, UBE2O acted as a ubiquitin lipase and targeted AMPK alpha 2 for ubiquitin-dependent degradation in skeletal muscle; further, muscle-specific heterozygous knockout of Prkaa2 ablated UBE2O-controlled metabolic processes. These results identify the UBE2O/AMPK alpha 2 axis as both a potent regulator of metabolic homeostasis in skeletal muscle and a therapeutic target in the treatment of diabetes and metabolic disorders.

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