LAUSR

As a well-conserved microRNA, miR-183 is ubiquitously expressed in many tissues and cells including backfat and the 3T3-L1 adipocytes; however, the mechanisms regulating miR-183 in adipogenesis remain poorly understood. Here, we explored the expression pattern and role of miR-183 in adipogenesis using hircine preadipocytes. The results showed that miR-183 was up-regulated during preadipocyte differentiation, and overexpression of miR-183 enhanced lipid accumulation and dramatically increased the mRNA expression of the adipogenic genes PPARγ, C/EBPα, SREBP-1c, FAS, and ACC. Using bioinformatics tools, we predicted Smad4 to be a target of miR-183. This was subsequently validated with a luciferase reporter assay. Overexpression of miR-183 suppressed the mRNA and protein levels of Smad4 significantly, whereas inhibiting miR-183 had the opposite effect. However, inhibition of Smad4 greatly accelerated lipid deposition and increased the expression of adipogenic genes which consists with the results of miR-183 overexpression. In conclusion, these results indicate that miR-183 promotes hircine preadipocyte differentiation by targeting Smad4.