The role of microRNA-26b in human adipocyte differentiation and proliferation.

Recent findings indicate that microRNAs (miRNAs) are involved in the regulatory network of adipogenesis and obesity. Thus far, only a few human miRNAs are known to function as adipogenic regulators, fanning interest in studies on the functional role of miRNAs during adipogenesis in humans. In a previous study, we used a microarray to assess miRNA expression during human preadipocyte differentiation. We found that expression of the miR-26b was increased in mature adipocytes. MiR-26b is an intronic miRNA located in the intron of CTDSP1 (carboxy terminal domain, RNA polymerase II, polypeptide A, small phosphatase 1). Target prediction and Renilla luciferase analyses revealed the phosphatase and tensin homolog gene (PTEN) as a putative target gene. In this study, we found that miR-26b was gradually upregulated during adipocyte differentiation. To understand the roles of miR-26b in adipogenesis, we adopted a loss-of-function approach to silence miR-26b stably in human preadipocytes. We found that miR-26b inhibition effectively suppressed adipocyte differentiation, as evidenced by decreased lipid droplets and the ability of miR-26b to decrease mRNA levels of adipocyte-specific molecular markers and triglyceride accumulation. Furthermore, the cell growth assay revealed that miR-26b inhibition promoted proliferation. Nevertheless, it had no effect on apoptosis. Taken together, these data indicate that miR-26b may be involved in adipogenesis and could be targeted for therapeutic intervention in obesity.