Adipose ABHD6 regulates tolerance to cold and thermogenic programs.

Enhanced energy expenditure in brown (BAT) and white (WAT) adipose tissues can be therapeutic against metabolic diseases. We examined the thermogenic role of adipose α/β-hydrolase domain-6 (ABHD6), which hydrolyzes monoacylglycerol (MAG), by employing adipose-specific ABHD6-KO mice. Control and KO mice show similar phenotype at room temperature and thermoneutral conditions. However, KO mice are resistant to hypothermia, which can be accounted for by the simultaneously increased lipolysis and lipogenesis of the thermogenic glycerolipid/free fatty acid (GL/FFA) cycle in visceral fat, despite unaltered UCP1 expression. Upon cold-stress, nuclear 2-MAG levels increase in visceral WAT of the KO mice. Evidence is provided that 2-MAG causes activation of PPARα in white adipocytes, leading to elevated expression and activity of GL/FFA cycle enzymes. In the ABHD6-ablated BAT, glucose and oxidative metabolism are elevated upon cold-induction, without changes in GL/FFA cycle and lipid turnover. Moreover, response to in vivo β3-adrenergic stimulation is comparable between KO and control mice. Our data reveal a MAG/PPARα/GL/FFA cycling metabolic signaling network in visceral adipose tissue, which contributes to cold-tolerance, and that adipose ABHD6 is a negative modulator of adaptive thermogenesis.