| First Author | Yamamoto K | Year | 2013 |
| Journal | J Biol Chem | Volume | 288 |
| Issue | 30 | Pages | 21648-58 |
| PubMed ID | 23775071 | Mgi Jnum | J:201764 |
| Mgi Id | MGI:5515676 | Doi | 10.1074/jbc.M113.481424 |
| Citation | Yamamoto K, et al. (2013) A novel function of Onecut1 protein as a negative regulator of MafA gene expression. J Biol Chem 288(30):21648-58 |
| abstractText | The transcription factor MafA is a key regulator of insulin gene expression and maturation of islet beta cells. Despite its importance, the regulatory mechanism of MafA gene expression is still unclear. To identify the transcriptional regulators of MafA, we examined various transcription factors, which are potentially involved in beta cell differentiation. An adenovirus-mediated overexpression study clearly demonstrated that Onecut1 suppresses the promoter activity of MafA through the Foxa2-binding cis-element on the MafA enhancer region (named area A). However, ChIP analysis showed that Foxa2 but not Onecut1 could directly bind to area A. Furthermore, overexpression of Onecut1 inhibited the binding of Foxa2 onto area A upon ChIP analysis. Importantly, insertion of a mutation in the Foxa2-binding site of area A significantly decreased the promoter activity of MafA. These findings suggest that Onecut1 suppresses MafA gene expression through the Foxa2-binding site. In the mouse pancreas, MafA expression was first detected at the latest stage of beta cell differentiation and was scarcely observed in Onecut1-positive cells during pancreas development. In addition, Onecut1 expression was significantly increased in the islets of diabetic db/db mice, whereas MafA expression was markedly decreased. The improved glucose levels of db/db mice with insulin injections significantly reduced Onecut1 expression and rescued the reduction of MafA expression. These in vivo experiments also suggest that Onecut1 is a negative regulator of MafA gene expression. This study implicates the novel role of Onecut1 in the control of normal beta cell differentiation and its involvement in beta cell dysfunction under diabetic conditions by suppressing MafA gene expression. |
