Lang Hongmei, Xiang Yang, Lin Ning, Ai Zhihua, You Zhiqing, Xiao Jie, Liu Dan, Yang Yongjian
Cell Physiol Biochem. 2018;48(1):185-193. doi: 10.1159/000491717. Epub 2018 Jul 13.
BACKGROUND/AIMS: MicroRNAs (miRNAs) are a novel class of small RNAs that participate in a variety of biological processes. Although miRNAs have been linked to insulin synthesis and glucose homeostasis, their role in the targeting of mitochondrial uncoupling protein 2 (UCP2), a negative modulator of insulin secretion, remains unclear.
miRNA levels were determined by real-time quantitative PCR analysis using TaqMan probes, and insulin secretion from isolated islets was quantified by ELISA. Effects of miRNAs on UCP2 expression were checked with a luciferase assay and western blotting analysis.
An overall change in a set of miRNAs was discovered, with miR-15a, miR-424, miR-497, and miR-185 coinciding with insulin levels in islets maintained under high-glucose conditions. Moreover, experiments in MIN6 cells illustrated that miR-15a, miR-424, miR-497, and miR-185 positively regulated insulin biosynthesis by co-inhibiting UCP2 expression. Furthermore, the four miRNAs were found to post-transcriptionally repress UCP2 expression by directly targeting the 3'UTR of UCP2 mRNA.
Thus, our results shed further light on the regulatory network in β-cells consisting of miRNAs, UCP2, and insulin and provide novel therapeutic targets for diabetes.
背景/目的：微小RNA（miRNA）是一类新型小RNA，参与多种生物学过程。尽管miRNA已被证明与胰岛素合成及葡萄糖稳态有关，但其在靶向线粒体解偶联蛋白2（UCP2，胰岛素分泌的负调节因子）中的作用仍不清楚。
使用TaqMan探针通过实时定量PCR分析确定miRNA水平，并用ELISA对分离胰岛的胰岛素分泌进行定量。通过荧光素酶测定和蛋白质印迹分析检查miRNA对UCP2表达的影响。
发现一组miRNA发生整体变化，其中miR-15a、miR-4,24、miR-497和miR-185与在高糖条件下维持的胰岛中的胰岛素水平一致。此外，在MIN6细胞中的实验表明，miR-15a、miR-424、miR-497和miR-185通过共同抑制UCP2表达来正向调节胰岛素生物合成。此外，发现这四种miRNA通过直接靶向UCP2 mRNA的3'UTR在转录后抑制UCP2表达。
因此，我们的结果进一步揭示了由miRNA、UCP2和胰岛素组成的β细胞调节网络，并为糖尿病提供了新的治疗靶点。
