Abstract
Obesity is characterized by macrophage infiltration into adipose tissue. White adipose tissue remodelling under inflammatory conditions involves both hypertrophy and adipogenesis and is regulated by transcription factors, which are influenced by bone morphogenetic protein (BMP) signalling. MicroRNAs (miRNAs) regulate gene expression and are involved in obesity-related processes such as adipogenesis. Therefore, we identified differentially expressed miRNAs in the epididymal white adipose tissue (eWAT) of mice fed a normal diet (ND) and those fed a high-fat diet (HFD). The expression of miR-6402 was significantly suppressed in the inflamed eWAT of HFD-fed mice than in ND-fed mice. Furthermore, Bmpr2, the receptor for BMP4, was identified as a target gene of miR-6402. Consistently, miR-6402 was downregulated in the inflamed eWAT of HFD-fed mice and in 3T3-L1 cells (preadipocytes) and differentiated 3T3-L1 cells (mature adipocytes) , and BMPR2 expression in these cells was upregulated. Adipogenesis was induced in WAT by BMP4 injection (in vivo) and in 3T3-L1 cells by BMP4 stimulation (in vitro), both of which were inhibited by miR-6402 transfection. Inflamed eWAT showed higher expression of BMPR2 and the adipogenesis markers C/EBPβ and PPARγ, which was suppressed by miR-6402 transfection. Our findings suggest that miR-6402 is a novel anti-adipogenic miRNA that combats obesity by inhibiting the BMP4/BMPR2 signalling pathway and subsequently reducing adipose tissue expansion.