Interferon-alpha inhibits adipogenesis via regulation of JAK/STAT1 signaling.

ABSTRACT

BACKGROUND INFORMATION Adipose tissue regulates energy metabolism by means of adipocyte hypertrophy and/or the differentiation of pre-existing adipocytes. Excessive production of some cytokines in adipose tissue is known to be a negative regulator of adipocyte differentiation, and the resulting impaired adipogenesis contributes to disorders like insulin resistance. IFN-α is a key immunoregulatory cytokine in the development of type 1 diabetes, lipid disorders and insulin resistance; however, its effect on adipogenesis remains unknown. METHOD: We examined the effect of IFN-α on adipocyte differentiation and its mechanisms. The effect of IFN-α on adipogenesis was evaluated by Western blotting, qRT-PCR, flow cytometric analysis and Oil Red O staining. We also investigated the role of STAT1 in adipogenesis using gene silencing analysis. RESULTS: IFN-α inhibited the accumulation of lipid droplets and the expression of adipogenesis related genes. The inhibition of adipocyte differentiation by IFN-α occurred in the early stages of differentiation. IFN-α arrested the cell cycle at the G0/G1 phase and regulated the expression of CDK2 and p21. These results were confirmed in MEF cells. Treatment with IFN-α increased STAT1 phosphorylation, and STAT1 siRNA or inhibitor prevented IFN-α from inhibiting the expression of PPARγ and C/EBPα as well as cell cycle progression in 3T3-L1 cells. CONCLUSION: We suggest that IFN-α inhibits adipocyte differentiation during the early stage of adipogenesis by regulating the expression of PPARγ and C/EBPα as well as the cell cycle through JAK/STAT1 signaling pathways. GENERAL SIGNIFICANCE: Our study provides new insights into possible mechanisms of the anti-adipogenetic effects of IFN-α.