microRNA参与调节硬脂酸诱导的胰岛β细胞功能障碍的分子机制研究

Metabolic syndrome induced by obesity have been severely threatening to human health in recent years. In which type 2 diabetes is the most representative because of its serious metabolic disorders and high prevelence. It has been accepted that free fatty acids (FFAs) affect insulin secretion, however, large amount of research should be done to confirm which kind of FFAs play the key role in the process of insulin release and its precise mechanisms. In our previous study, the change of steric acid (C18:0) level is significant and specific in postprandial serum FFAs profile whether the people have diabetes or hyperlipidemia. Meanwhile, we found that the function of panreatic β-cells was altered when exposure to C18:0 in vitro, and obviously differed from the effect of other FFAs. It has been reported that microRNA (miRNA) plays an important role in regulating insulin secretion, but no evidence has been added that there is any relationship between miRNA and dysfunction of insulin release induced by C18:0. Therefore, it is the first time to explore the molecular mechanism related to miRNA for dysfunction of pancreatic β-cells interfered with C18:0 in this project. Also, it provides innovative idea and theoretical basis for developing novel therapeutic agents and preventing type 2 diabetes.

肥胖引起的一系列代谢综合征严重威胁人类健康。其中，2型糖尿病以其较为严重的代谢紊乱和高患病率而最具代表性。已公认游离脂肪酸影响胰岛素分泌，但具体哪一种脂肪酸起到关键作用及其确切机制尚需大量研究证实。我们前期研究发现，无论高脂人群还是糖尿病人群，在其餐后血清游离脂肪酸谱的变化中，硬脂酸（C18:0）变化最为显著且特异；在体外实验中，我们也发现硬脂酸的含量变化能够引起胰岛β细胞功能改变，且变化明显有别于其他饱和脂肪酸的影响。有报道发现microRNA在胰岛素分泌过程中发挥着重要调节作用，但尚未有人指出硬脂酸诱导的胰岛素分泌改变与其有关。因此，本项目首次探索microRNA参与调节硬脂酸诱导的胰岛β细胞功能障碍的分子机制，这将为探索胰岛素分泌障碍发生发展机制提供新思路，为今后开发新型治疗药物奠定了理论基础和研究平台，同时针对胰岛β细胞功能障碍引起的2型糖尿病提出了全新的防控策略。

在高脂血症和2型糖尿病人群中，血清硬脂酸水平是升高的，但是其对胰岛B细胞脂毒性损伤机制不明。本课题旨为探讨高浓度的硬脂酸对胰岛B细胞的损伤作用及其机制。分别给予C57BL6小鼠干预正常饲料、高硬脂酸含量和高软脂酸含量的饲料，喂养24周后，通过基因芯片技术检测microRNA表达谱的变化。通过胰岛B细胞TUNEL染色检测胰岛损伤情况。通过胰胆管注射慢病毒抑制胰岛的miR-34a-5p的表达。结果提示，无论动物体内还是体外INS-1细胞中，硬脂酸均能够引起显著的脂毒性损伤，是通过上调miR-34a-5p而抑制抗凋亡蛋白BCL-2和BCL-W表达发挥作用。硬脂酸引起的胰岛素分泌障碍也会被miR-34a-5p的抑制所缓解。进一步的研究发现，在INS-1细胞中，抑制p53能逆转硬脂酸引起的miR-34a-5p水平升高，这可能是由于硬脂酸激活了PERK。抑制PERK后能够下调硬脂酸引起的p53水平升高和脂毒性损伤。这一研究给硬脂酸引起的胰岛细胞损伤提供了理论基础，同时为2型糖尿病发生发展过程中胰岛B细胞损伤的预防和改善提供了新的靶点。