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 β-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.

The Siberian sturgeon Acipenser baerii is a critically endangered fish in Acipenseriformes. Owing to increasing demand for the caviar production with this species, Siberian sturgeon has become one of the most popularly aquacultured Acipenser species worldwide (Gisbert and Ruban, 2003; Doukakis et al., 2012). This sturgeon species was also introduced into the Korean aquaculture domain in the late 1990s, and from then on, early pioneering works on artificial fingerling production (Park et al., 2013a, 2013b) have been followed by a wide spectrum of studies including evolution (Kim et al., 2019a), cell cul