Conclusions
Our results suggest FSTL1 as a novel stimulator of the β-adrenergic signaling and BAT thermogenesis.
Methods
Whole-body ablation Fstl1 heterozygous mice (Fstl1+/-) and its littermates control were injected with CL316,243 to assess energy balance. A series of FSTL1 overexpression and knockdown experiments were carried out to evaluate its function in regulating thermogenic gene expression in brown adipocytes.
Results
FSTL1 expression was induced upon BAT activation during cold challenge or β3-adrenergic activation. FSTL1 haploinsufficiency in mice led to reduced thermogenic gene expression, impaired BAT recruitment, and decreased heat production. FSTL1 cell-autonomously promoted the β3-adrenergic signaling, which was required to upregulate PPARγ and UCP1 in brown adipocytes. Furthermore, only glycosylated FSTL1 could be secreted from brown adipocytes to induce the β3-adrenergic activation. Conclusions: Our results suggest FSTL1 as a novel stimulator of the β-adrenergic signaling and BAT thermogenesis.