miR-152-3p/线粒体途径在2型糖尿病发生中的作用机制研究

Pancreatic beta cell dysfunction is the key step to determine the progression of T2DM from impaired glucose tolerance, and mitochondrial dysfunction is one of the main reasons for the damage of pancreatic beta cells, whereas little has been elucidated for this aspect. Our publication has shown that normal mitochondrial transcription and replication is subject to the level of TFAM. Meanwhile, the expression of TFAM is activated indirectly by PGC-1α. Preliminary experiments indicated that miR-152-3p was abnormally elevated in the peripheral blood of patients with T2DM; on the contrary, levels of PGC-1α and mtDNA were decreased, and level of miR-149-3p is positively correlated with level of fasting blood glucose. Meanwhile, bioinformatics prediction indicated that PGC-1α was one of the potential targets of miR-152-3p. We predicate that miR-152-3p-mediated downregulation of PGC-1α inhibits the expression of TFAM, decreases the mitochondrial content and function and finally reduces the function of pancreatic beta cells. In specific aim of this proposal, we will further analyze the relationship between the level of miR-152-3p and diabetic clinical indexes, and investigate how the changes of miR-152-3p level influence the expression of PGC-1α and TFAM, content and function of mitochondria, and the insulin secretion of pancreatic beta cells. The results of this project will elucidate the cause of pancreatic beta cell dysfunction and the molecular pathogenesis of T2DM, which may also provide novel diagnostic marker and therapeutic candidate for T2DM.

胰岛β细胞功能障碍是从糖耐量异常转变为T2DM的关键环节，而线粒体功能异常又是造成β细胞功能受损的重要原因，但其机制尚未阐明。TFAM决定线粒体的转录和复制，同时又受到PGC-1α的调控。前期研究发现，miR-152-3p水平在T2DM人群中异常升高，而PGC-1α表达及mtDNA拷贝数下降，且miR-152-3p水平与空腹血糖水平呈正相关。预测表明PGC-1α是miR-152-3p的潜在靶基因，我们推测miR-152-3p可能通过干扰PGC-1α的表达抑制TFAM水平及线粒体功能，造成β细胞功能障碍。本研究将进一步分析miR-152-3p水平与糖尿病指标的关系，并在细胞和动物水平上，确定miR-152-3p水平变化对PGC-1α、TFAM水平、线粒体含量和功能及胰岛素分泌能力的影响。本研究有助于阐明T2DM 胰岛β细胞功能障碍发生的机制，并为T2DM的诊断和治疗提供新的标志物和药物靶点。

阐明T2DM发生的分子机制有助于新药的开发，挽救T2DM患者的生命健康。本项目中我们系统研究了miR-152-3p通过靶向干扰促糖尿病基因EGR1的表达抑制T2DM发生的分子机制。我们的研究表明，miR-152-3p在胰岛素抵抗细胞模型、T2DM小鼠模型以及T2DM患者中的表达水平均明显降低，并与健康人群和T2DM患者的空腹血糖水平和肥胖指数呈明显负相关，或可作为辅助T2DM临床早期诊断的分子标志物。由于miR-152-3p通过抑制ATP生成干扰胰岛素分泌的分子机制已被国外同行率先报道，为保证项目的创新性，我们重点研究了miR-152-3p在T2DM胰岛素抵抗病变过程中的作用机制。结果表明，miR-152-3p发挥抑制胰岛素抵抗发生的作用。过表达miR-152-3p能够降低胰岛素抵抗小鼠的血糖水平并改善其胰岛素抵抗症状；抑制内源性miR-152-3p功能会损伤其糖代谢能力。对过表达miR-152-3p小鼠的肝脏进行转录组测序分析后发现，EGR1基因的mRNA水平明显下调；生物信息学分析也发现其mRNA的3’-非翻译区含有与miR-152-3p种子区互补的潜在位点。随后的体内外实验证实，miR-152-3p通过直接抑制EGR1基因的表达水平发挥生物学功能，初步揭示了miR-152-3p抑制胰岛素抵抗和T2DM发生的分子机制。本课题的顺利实施，揭示了miR-152-3p在T2DM早期临床诊断中的潜在应用价值，以及抑制胰岛素抵抗和T2DM发生的潜在分子机制。但由于研究经费和时间有限，T2DM病变过程中miR-152-3p表达失衡的分子机制仍需深入研究。本项目所得结果有助于鉴定miR-152-3p是辅助T2DM早期临床诊断的分子标志物和治疗T2DM的潜在药物靶向，对其它代谢类疾病的预防、早期诊断和治疗也具有潜在指导意义。