Distinct cellular and molecular mechanisms for β3 adrenergic receptor-induced beige adipocyte formation.

Beige/brite adipocytes are induced within white adipose tissues (WAT) and, when activated, consume glucose and fatty acids to produce heat. Classically, two stimuli have been used to trigger a beiging response: cold temperatures and beta 3-adrenergic receptor (Adrb3) agonists. These two beiging triggers have been used interchangeably but whether these two stimuli may induce beiging differently at cellular and molecular levels remains unclear. Here, we found that cold-induced beige adipocyte formation requires Adrb1, not Adrb3, activation. Adrb1 activation stimulates WAT resident perivascular (Acta2+) cells to form cold-induced beige adipocytes. In contrast, Adrb3 activation stimulates mature white adipocytes to convert into beige adipocytes. Necessity tests, using mature adipocyte-specific Prdm16 deletion strategies, demonstrated that adipocytes are required and are predominant source to generate Adrb3-induced, but not cold induced, beige adipocytes. Collectively, we identify that cold temperatures and Adrb3 agonists activate distinct cellular populations that express different beta-adrenergic receptors to induce beige adipogenesis.