Pivotal Role of <i>O</i>-GlcNAc Modification in Cold-Induced Thermogenesis by Brown Adipose Tissue Through Mitochondrial Biogenesis.

Abstract

Adipose tissues considerably influence metabolic homeostasis, and both white (WAT) and brown (BAT) adipose tissue play significant roles in lipid and glucose metabolism. <i>O</i>-linked <i>N</i>-acetylglucosamine (<i>O</i>-GlcNAc) modification is characterized by the addition of <i>N</i>-acetylglucosamine to various proteins by <i>O</i>-GlcNAc transferase (Ogt), subsequently modulating various cellular processes. However, little is known about the role of <i>O</i>-GlcNAc modification in adipose tissues. Here, we report the critical role of <i>O</i>-GlcNAc modification in cold-induced thermogenesis. Deletion of <i>Ogt</i> in WAT and BAT using adiponectin promoter-driven Cre recombinase resulted in severe cold intolerance with decreased uncoupling protein 1 (Ucp1) expression. Furthermore, <i>Ogt</i> deletion led to decreased mitochondrial protein expression in conjunction with decreased peroxisome proliferator-activated receptor γ coactivator 1-α protein expression. This phenotype was further confirmed by deletion of <i>Ogt</i> in BAT using Ucp1 promoter-driven Cre recombinase, suggesting that <i>O</i>-GlcNAc modification in BAT is responsible for cold-induced thermogenesis. Hypothermia was significant under fasting conditions. This effect was mitigated after normal diet consumption but not after consumption of a fatty acid-rich ketogenic diet lacking carbohydrates, suggesting impaired diet-induced thermogenesis, particularly by fat. In conclusion, <i>O</i>-GlcNAc modification is essential for cold-induced thermogenesis and mitochondrial biogenesis in BAT. Glucose flux into BAT may be a signal to maintain BAT physiological responses.