NT-PGC-1α deficiency decreases mitochondrial FA oxidation in brown adipose tissue and alters substrate utilization in vivo

Abstract

Transcriptional coactivator PPAR γ coactivator (PGC)-1α and its splice variant N-terminal (NT)-PGC-1α mediate transcriptional regulation of brown adipose tissue (BAT) thermogenesis in response to changes in ambient temperature. PGC-1α is dispensable for cold-induced BAT thermogenesis as long as NT-PGC-1α is present. However, the functional significance of NT-PGC-1α in BAT has not been determined. In the present study, we generated NT-PGC-1α−/− mice to investigate the effect of NT-PGC-1α deficiency on adaptive BAT thermogenesis. At thermoneutrality, NT-PGC-1α−/− mice exhibited abnormal BAT phenotype with increased accumulation of large lipid droplets concomitant with marked downregulation of FA oxidation (FAO)-related genes. Consistent with transcriptional changes, mitochondrial FAO was significantly diminished in NT-PGC-1α−/− BAT. This alteration, in turn, enhanced glucose utilization within the NT-PGC-1α−/− BAT mitochondria. In line with this, NT-PGC-1α−/− mice had higher reliance on carbohydrates. In response to cold or β3-adrenergic receptor agonist, NT-PGC-1α−/− mice transiently exhibited lower thermogenesis but reached similar thermogenic capacities as their WT littermates. Collectively, these findings demonstrate that NT-PGC-1α is an important contributor to the maintenance of FAO capacity in BAT at thermoneutrality and provide deeper insights into the relative contributions of PGC-1α and NT-PGC-1α to temperature-regulated BAT remodeling.

Keywords

• thermogenesis
• beta-3 adrenergic receptor
• fatty acid
• N-terminal peroxisome proliferator-activated receptor gamma coactivator 1-alpha