Abstract
FGF21 is an endocrine hormone that regulates energy homeostasis and insulin sensitivity. The mechanism of FGF21 action and the tissues responsible for these effects have been controversial, with both adipose tissues and the central nervous system having been identified as the target site mediating FGF21-dependent increases in insulin sensitivity, energy expenditure, and weight loss. Here we show that, while FGF21 signaling to adipose tissue is required for the acute insulin-sensitizing effects of FGF21, FGF21 signaling to adipose tissue is not required for its chronic effects to increase energy expenditure and lower body weight. Also, in contrast to previous studies, we found that adiponectin is dispensable for the metabolic effects of FGF21 in increasing insulin sensitivity and energy expenditure. Instead, FGF21 acutely enhances insulin sensitivity through actions on brown adipose tissue. Our data reveal that the acute and chronic effects of FGF21 can be dissociated through adipose-dependent and -independent mechanisms.