Full activation of thermogenesis in brown adipocytes requires Basigin action

Exploring mechanisms responsible for brown adipose tissue's (BAT) high metabolic activity is crucial to exploit its energy‐dissipating ability for therapeutic purposes. Basigin (Bsg), a multifunctional highly glycosylated transmembrane protein, was recently proposed as one of the 98 critical markers allowing to distinguish ‘white’ and ‘brown’ adipocytes, yet its function in thermogenic brown adipocytes is unknown. Here, we report that Bsg is negatively associated with obesity in mice. By contrast, Bsg expression increased in the mature adipocyte fraction of BAT upon cold acclimation. Additionally, Bsg levels were highly induced during brown adipocyte maturation in vitro and were further increased upon β‐adrenergic stimulation in a HIF‐1α‐dependent manner. siRNA‐mediated Bsg gene silencing in cultured brown adipocytes did not impact adipogenesis nor mitochondrial function. However, a significant decrease in mitochondrial respiration, lipolysis and Ucp1 transcription was observed in adipocytes lacking Bsg, when activated by norepinephrine. Furthermore, using gas chromatography/mass spectrometry–time‐of‐flight analysis to assess the composition of cellular metabolites, we demonstrate that brown adipocytes lacking Bsg have lower levels of intracellular lactate and acetoacetate. Bsg was additionally required to regulate intracellular AcAc and tricarboxylic acid cycle intermediate levels in NE‐stimulated adipocytes. Our study highlights the critical role of Bsg in active brown adipocytes, possibly by controlling cellular metabolism. A better understanding of underlying mechanisms mediating the remarkable energy‐dissipating capacity of brown adipose tissue (BAT) is necessary to explore its therapeutic potential for the treatment of obesity. Here, we reveal the dynamic regulation of a transmembrane protein Basigin in BAT and its previously uncharacterized role in brown fat function. We demonstrate that Basigin controls key processes crucial for the proper activation of BAT including Ucp1 expression, lipolysis and cellular metabolism.