MicroRNA 21 regulates the proliferation of human adipose tissue-derived mesenchymal stem cells and high-fat diet-induced obesity alters microRNA 21 expression in white adipose tissues.

A better understanding of the molecular mechanisms that govern human adipose tissue-derived mesenchymal stem cells (hASCs) differentiation could provide new insights into a number of diseases including obesity. Our previous study demonstrated that microRNA-21 (miR-21) controls the adipogenic differentiation of hASCs. In this study, we determined the expression of miR-21 in white adipose tissues in a high-fat diet (HFD)-induced obesity mouse model to examine the relationship between miR-21 and obesity and the effect of miR-21 on hASCs proliferation. Our study showed biphasic changes of miR-21 expression and a correlation between miR-21 level and adipocyte number in the epididymal fat of HFD mice. Over-expression of miR-21 decreased cell proliferation, whereas inhibiting miR-21 with 2'-O-methyl-antisense RNA increased it. Over-expression of miR-21 decreased both protein and mRNA levels of STAT3, whereas inhibiting miR-21 with 2'-O-methyl-antisense RNA increased these levels. The activity of a luciferase construct containing the miR-21 target site from the STAT3 3'UTR was lower in LV-miR21-infected hASCs than in LV-miLacZ infected cells. RNA interference-mediated down-regulation of STAT3 decreased cell proliferation without affecting adipogenic differentiation. These findings provide the evidence of the correlation between miR-21 level and adipocyte number in the white adipose tissue of HFD-induced obese mice, which provides new insights into the mechanisms of obesity.