MicroRNA-125a-3p expression in abdominal adipose tissues is associated with insulin signalling gene expressions in morbid obesity: Observations in Taiwanese

Background: Micro (mi) RNAs have been found to play an important role in the regulation of adipogenesis and insulin sensitivity. However, associations between miRNA and insulin signalling-related gene expressions in abdominal adipose tissues in obese subjects remain unclear. Methods: We used a microarray platform to screen miRNA expressions in abdominal adipose tissues between genders in severely obese subjects and found that the top-ranking miRNA in abdominal omental adipose tissues was miRNA-125a-3p. MicroR-125a-3p and insulin signalling-related gene expressions in abdominal omental adipose tissues of all subjects (11 men and 10 women) were subsequently quantified by a real-time PCR. Also, associations of miR-125a-3p with insulin signallingrelated gene expression and biochemical markers in obese subjects were analyzed by a linear regression analysis. Results: miR-125a-3p expressed by abdominal omental adipose tissues was much higher in obese men than women. No gender difference was observed in abdominal subcutaneous adipose tissues. Concomitant with high miR-125a-3p, c-Jun N-terminal kinase gene expression was also higher, whereas insulin receptor was lower in men than women. There were negative associations of miR-125a-3p with the insulin receptor and phosphatidylinositol 3-kinase expressions. Fasting plasma glucose and cholesterol levels were positively associated with miR- 125a-3p expression. These associations were obvious in obese men but not women. Conclusion: Our results support the involvement of miR-125a-3p in regulating the insulin signalling pathway and imply that increased miR- 125a-3p expression in omental adipose tissues may be a characteristic feature of insulin resistance in obese men.