FGF21 resistance is not mediated by downregulation of beta-klotho expression in white adipose tissue

OBJECTIVE Fibroblast growth factor 21 (FGF21) is an endocrine hormone that regulates metabolic homeostasis. Previous work has suggested that impairment of FGF21 signaling in adipose tissue may occur through downregulation of the obligate FGF21 co-receptor, β-klotho, which leads to "FGF21 resistance" during the onset of diet-induced obesity. Here, we sought to determine whether maintenance of β-klotho expression in adipose tissue prevents FGF21 resistance and whether other mechanisms also contribute to FGF21 resistance in vivo. METHODS We generated adipose-specific β-klotho transgenic mice to determine whether maintenance of β-klotho expression in adipose tissue prevents FGF21 resistance in vivo. RESULTS β-klotho protein levels are markedly decreased in white adipose tissue, but not liver or brown adipose tissue, during diet-induced obesity. Maintenance of β-klotho protein expression in adipose tissue does not alleviate impaired FGF21 signaling in white adipose or increase FGF21 sensitivity in vivo. CONCLUSIONS In white adipose tissue, downregulation of β-klotho expression is not the major mechanism contributing to impaired FGF21 signaling in white adipose tissue.