miR-190调控糖脂毒性诱导的胰岛β-细胞功能损伤的作用及机制

High level of glucose and FFAs leads to dysfunction of pancreatic β-cells followed by defects in insulin secretion have been described as the key feature of type 2 diabetes. We have demonstrated previously for the first time that pancreatic β-cell function, such as insulin biosynthesis and secretion, was impaired under the chronic high level of glucose and/or FFAs through NOX2-induced oxidative stress. Behind this, microRNA is proposed to play an important role in β-cell, tissue dysfunction and damage. In our recent research, low level of miR-190 was found in β-cell from high-throughput screening results, while increased miR-190 could improve insulin level. Considering Cybb(NOX2) might be the target of miR-190 through bioinformatics prediction, we hypothesized that miR-190 was involved in the injury process of β-cell by affecting NOX2. To test this hypothesis, we explore the role of miR-190 in the injury process of β-cell from the molecular, cellular, organizations and the overall level by using cellular and animal models; we investigate whether the regulation of miR-190 is related to NOX2; and we explore the regulation mechanism of miR-190 in high level of glucose and FFAs induced β-cell dysfunction. This project will reveal the mechanism of β-cell damage in type 2 diabetes from the new point of view and provide new perspective for its prevention.

高糖、高脂导致胰岛β-细胞损伤造成胰岛素分泌不足是2型糖尿病的主要病因。microRNA参与调节胰岛β-细胞的发育、增殖和凋亡，胰岛素的合成、分泌。我们已有研究首次发现，糖脂毒性通过NADPH氧化酶2(NOX2)引起胰岛β-细胞损伤。最近高通量筛查发现糖脂毒性导致β-细胞miR-190显著降低，而上调miR-190能有效升高胰岛素水平，且生物信息学分析Cybb(NOX2)是miR-190的潜在靶标。由此提出假说：miR-190可能通过NOX2调控糖脂毒性诱导的胰岛β-细胞损伤。为验证这一假说，本课题拟采用细胞和小鼠模型，从分子、细胞及动物水平等多层次明确miR-190在胰岛β-细胞损伤中的作用，阐明miR-190对NOX2的调控机理，探讨miR-190调控胰岛β-细胞功能损伤的分子机制。本研究将从miRNA的新视点探讨胰岛β-细胞损伤机制，为2型糖尿病的防治提供新的思路。

2型糖尿病是一种慢性代谢性疾病，其主要特点是胰岛β-细胞功能损伤和胰岛素抵抗。最近的研究表明，miR-190在肿瘤细胞的生长和转移中起着重要的作用，然而，miR-190在胰岛β-细胞糖脂毒性中的作用并不十分清楚。本研究发现miR-190在db/db小鼠的胰腺和33.3mM葡萄糖处理的NIT-1细胞中低表达，同事伴随有胰岛素表达受损。而过表达miR-190能够上调高糖处理后NIT-1细胞中胰岛素和Pdx-1的表达。与体外实验结果一致，在db/db小鼠中通过尾静脉注射miR-190/纳米颗粒复合物能够显著降低小鼠的空腹血糖水平和血胰岛素水平，改善db/db小鼠胰腺中胰岛素和Pdx-1水平。此外，过表达miR-190能够降低NIT-1细胞的凋亡。luciferase报告结果显示miR-190通过与NOX2的3’-UTR结合抑制NOX2水平。更重要的是，过表达miR-190能够降低NIT-1细胞中高糖诱导的ROS生成；在db/db小鼠体内过表达miR-190也能够通过抑制NOX2表达从而降低ROS 水平。进一步的研究结果发现，miR-190通过PTEN/Akt和p38 MAPK/p53通路参与了胰岛β-细胞的功能失调和凋亡。我们的结果为miR-190靶向调控NOX2从而参与胰岛β-细胞的功能失调和凋亡的机制提供了新的视野。