IL-6 and TNF-α induced obesity-related inflammatory response through transcriptional regulation of miR-146b.

Obesity is associated with a low-grade inflammation of white adipose tissue, which can subsequently lead to insulin resistance, impaired glucose tolerance, and even diabetes. MicroRNAs (miRNAs) have been implicated as negative regulators controlling diverse biological processes at the level of post-transcriptional repression. miR-146b is an intergenic miRNA that can regulate the inflammatory process by attenuating cytokine signaling via the nuclear factor-κB pathway. In this study, we focused on investigating the expression of miR-146b in mature human adipocytes and their response to proinflammatory cytokines. Our results showed that miR-146b was highly expressed in the mature adipocytes. The mature human adipocytes responded to proinflammatory cytokines (TNF-α and IL-6) by highly increasing the expression of miR-146b. We cloned and identified a potential promoter of the transcriptional regulation of miR-146b. Interestingly, a fragment about 950-bp length upstream sequences of miR-146b had apparent transcription activity. In addition, the increase in miR-146b promoter activity by TNF-α and IL-6 was also effectively elevated. Our results indicated that a novel role for miR-146b in adipose tissue inflammation and miR-146b may be an important mediator in the process of obesity complications via its own transcription mechanism.