p53 regulates expression of uncoupling protein 1 through binding and repression of PPARγ coactivator 1α

The tumor suppressor p53 (TRP53 in mice) is known for its involvement in carcinogenesis, but work during recent years has underscored the importance of p53 in the regulation of whole body metabolism. A general notion is that p53 is necessary for efficient oxidative metabolism. The importance of UCP1-dependent uncoupled respiration and increased oxidation of glucose and fatty acids in brown or brown-like, termed BRITE or beige, adipocytes in relation to energy balance and homeostasis has recently been highlighted. UCP1-dependent uncoupled respiration in classic interscapular brown adipose tissue is central to cold-induced thermogenesis, whereas BRITE/beige adipocytes are of special importance in relation to diet-induced thermogenesis, where the importance of UCP1 is only clearly manifested in mice kept at thermoneutrality. We challenged wildtype and TRP53-deficient mice by high fat feeding under thermoneutral conditions. Interestingly, mice lacking TRP53 gained less weight compared to their wildtype counterparts. This was related to an increased expression of Ucp1 and other PPARGC1a and PPARGC1b target genes, but not Ppargc1a or Ppargc1b in inguinal white adipose tissue of mice lacking TRP53. We show that TRP53, independently of its ability to bind DNA, inhibits the activity of PPARGC1a and PPARGC1b. Collectively, our data shows that TRP53 has the ability to regulate the thermogenic capacity of adipocytes through modulation of PPARGC1 activity.