Browning of white adipose tissue (WAT) has been recognized as an important strategy for the treatment of obesity, insulin resistance, and diabetes. Enoyl coenzyme A hydratase 1 (ECH1) is a widely known enzyme involved in lipid metabolism. However, whether and how ECH1 is implicated in browning of WAT remain obscure. Adeno-associated, virus-mediated genetic engineering of ECH1 in adipose tissue was used in investigations in mouse models of obesity induced by a high-fat diet (HFD) or browning induced by cold exposure. Metabolic parameters showed that ECH1 overexpression decreased weight gain and improved insulin sensitivity and lipid profile after 8 wk of an HFD. Further work revealed that these changes were associated with enhanced energy expenditure and increased appearance of brown-like adipocytes in inguinal WAT, as verified by a remarkable increase in uncoupling protein 1 and thermogenic gene expression. In vitro, ECH1 induced brown fat-related gene expression in adipocytes differentiated from primary stromal vascular fractions, whereas knockdown of ECH1 reversed this effect. Mechanistically, ECH1 regulated the thermogenic program by inhibiting mammalian target of rapamycin signaling, which may partially explain the potential mechanism for ECH1 regulating adipose browning. In summary, ECH1 may participate in the pathology of obesity by regulating browning of WAT, which probably provides us with a new therapeutic strategy for combating obesity.
Keywords: adipose browning; enoyl coenzyme A hydratase 1; mammalian target of rapamycin; obesity; uncoupling protein 1.