Abstract
OBJECTIVES: Depression of the Notch/Hes1 pathway has been reported to play a role in abnormal differentiation of intestinal epithelial cells (IECs) in diabetes mellitus (DM). However, the mechanism by which this pathway influences IEC differentiation has remained unclear. In this study, we have investigated the role of microRNAs (miRNAs) in regulating the Notch/Hes1 pathway in IECs of DM mice. MATERIALS AND METHODS: Integrated comparative miRNA microarray technology was used to determine the expression profile of miRNAs in IECs of DM mice. After bioinformatic analysis, an miRNA with altered expression levels, miRNA-30e, was identified as a candidate for regulating the Notch pathway in DM. A luciferase reporter assay confirmed that miRNA-30e targeted 3'-UTR of the Notch gene. The role of miRNA-30e in regulating Notch signalling was then explored by up- and downregulating its expression in vitro and in vivo. RESULTS: Abnormal differentiation of IECs in DM mice was associated with reduced activity of the Dll4/NICD/Hes1 signal pathway. Based on bioinformatic analyses, increased expression of miRNA-30e was identified as a potential candidate for regulating Notch signalling. miRNA-30e targeted the 3'-UTR of Dll4 and downregulated Dll4 expression in primary IECs and IEC-6 cells. Exogenous miRNA-30e reduced activity of the Dll4/NICD/Hes1 pathway, and induced abnormal differentiation of IECs in normal mice. Conversely, treatment with miRNA-30e antagonist upregu-lated activity of the Dll4/NICD/Hes1 pathway in vivo, and normalized IEC differentiation in DM mice. CONCLUSIONS: Increased levels of miRNA-30e downregulated activity of the Dll4/NICD/Hes1 signalling pathway by targeting the 3'-UTR of Dll4, which contributed to abnormal differentiation in small intestinal epithelia of DM mice.