miR-107: a Toll-like receptor-regulated miRNA dysregulated in obesity and type II diabetes

miRNAs are small noncoding RNAs that act as regulators of gene expression. Dysregulation of miRNAs has been shown to contribute to multiple disease processes. It has become apparent that miRNAs play a key role in the innate immune response, whereby a large number of miRNAs have been demonstrated to be regulated by TLRs, key initiators of the innate immune response to infection. Recently, the LPS receptor, TLR4, has been shown to down-regulate miR-107 in macrophages. In addition, miR-107 has been demonstrated to be dysregulated in murine and rodent models of obesity and insulin resistance, respectively, with miR-107 contributing to both conditions. With obesity and inflammation being so intrinsically associated, the link between the miR-107 expression levels, inflammation, and insulin resistance may be of particular importance in metabolic diseases. The decrease in miR-107 in response to TLR4 may be an attempt to limit insulin resistance, a feature of obesity-related inflammation. If this process is impaired, disease, such as T2D, might persist. This review aims to discuss a possible link between the molecular phenomena of obesity and inflammation and the role that miR-107 may contribute to these processes. J. Leukoc. Biol. 92: 521-527; 2012.