Background : FGF(Fibroblast growth factor)21 is a metabolic regulator with pleiotropic effects on regulating glucose and lipid homeostasis and insulin sensitivity. Adipose tissue is a main target of FGF21 action. The endocrine action of FGF21 requires both FGF receptor and β-Klotho for signaling. The aim of this study was to investigate the expression of β-Klotho and to assess the correlation between levels of serum FGF21 and cytokines and expression of β-Klotho in adipocyte.
.Methods : A total of 38 women undergoing obstetric operation were recruited after informed consent. The oral glucose tolerance test was performed and omental adipose tissue samples were obtained in all subjects. Serum FGF21 level and cytokines levels were measured using ELISA kit and mRNA expression of β-Klotho in adipocyte using quantitative PCR. 
Results : Serum FGF21 levels increased in obese group (BMI≥25) compared with non-obese (BMI<25) group (P=0.042), and in IR (Insulin resistant) group (HOMA-IR≥2.5) compared with non-IR (HOMA-IR<2.5) group (P=0.057). And mRNA expressions of β-Klotho decreased in IR group compared with non-IR group (P=0.041), whereas mRNA expressions of FGF receptor was not different between two groups. Serum FGF21 levels was correlated with HOMA-IR (r=0.359), BMI (r=0.356) and HDL-C (r= -0.390). β-Klotho mRNA expression was correlated with fasting glucose (r= -0.334), resistin (r= -0.435) and IL-1β (r=0.373) not with HOMA-IR nor BMI. 
Conclusion : We showed mRNA expressions of β-Klotho in adipocyte decreased in insulin-resistant patients, and mRNA expressions of β-Klotho was correlated with proinflammatory cytokines. These results suggested that the reduction of β-Klotho expression could be one of factors which induce insulin resistance, and may be caused by adipose inflammation and proinflammatory cytokines.

Reduction of adipocyte β-klotho expression in insulin-resistant subjects