Sortilin-mediated translocation of ACSL1 impairs non-shivering thermogenesis

Abstract

Abstract Obesity and its related metabolic disorders are caused by an imbalance between homeostatic energy consumption and expenditure. Brown and beige adipose tissues have been shown to be protective against these diseases due to their critical roles in non-shivering thermogenesis; additionally, adrenergic innervation of these cells promotes lipolysis and fatty acid oxidation1. A key enzyme promoting fatty acid oxidation in adipose tissues, particularly in response to cold-stimulus, is mitochondrial acyl-CoA synthetase long-chain family member 1(ACSL1)2 However, the regulatory mechanism of the subcellular localization of ACSL1 in adipocytes remains poorly understood. Here, we identify an endosomal trafficking component sortilin (encoded by Sort1) in adipose tissues that facilitates the translocation of ACSL1 from mitochondria to lysosome for further degradation. In brown and beige adipose tissues, sortilin is downregulated upon adrenergic stimulation but its levels are restored to baseline after the stimulus is withdrawn. Depletion of Sort1 in adipocytes results in an increase in whole body energy expenditure. Moreover, mice with adipose-specific Sort1 depletion are resistant to high-fat diet (HFD)-induced obesity and insulin resistance. Collectively, our findings identify sortilin as a promising therapeutic target that negatively regulates non-shivering thermogenesis in adipocytes by promoting the translocation of ACSL1 from the mitochondria to lysosome.