The Correlation between MicroRNA-199a and White Adipose Tissue in C57/BL6J Mice with High-Fat Diet

Understanding is emerging about microRNAs as mediators in the regulation of white adipose tissue (WAT) and obesity. The expression level of miR-199a in mice was investigated to test our hypothesis: miR-199a might be related to fat accumulation and try to find its target mRNA, which perhaps could propose strategies with a therapeutic potential affecting the fat storage. C57/BL6J mice were randomly assigned to either a control group or an obesity model group (n=10 in both groups). Control mice were fed a normal diet (fat: 10 kcal %) ad libitum for 12 weeks, and model mice were fed a high-fat diet (fat: 30 kcal %) ad libitum for 12 weeks to induce obesity. At the end of the experiment, body fat mass and the free fatty acids (FFAs) and triglycerides (TGs) in WAT were tested. Fat cell size was measured by hematoxylin-eosin (H&E) staining method. The fat mass of the model group was higher than that of the control group (P<0.05). In addition, the concentrations of the FFAs and TGs were higher (P<0.05) and the adipocyte count was lower (P<0.05) in the model group. We tested the expression levels of miR-199a and key adipogenic transcription factors, including peroxisome proliferator activated receptor gamma2 (PPARγ2), CCAAT/enhancer binding proteins alpha (C/EBPα), adipocyte fatty acid-binding protein (aP2), and sterol regulatory element binding protein-1c (SREBP-1c). Up-regulated expression of miR-199a was observed in model group. Increased levels of miR-199a was accompanied by high expression levels of SREBP-1c. We found that the 3'-UTR of SREBP-1c mRNA has a predicted binding site for miR-199a. Based on the current discoveries, we suggest that miR-199a may exert its action by binding to its target mRNA and cooperate with SREBP-1c to induce obesity. Therefore, if the predicted binding site is confirmed by further research, miR-199a may have therapeutic potential for obesity.