微囊泡介导的miRNA调控脂肪细胞胰岛素抵抗的分子机制研究

Recently, many studies indicated that the release of pro-inflammation miRNAs by macrophages is enhanced by inflammatory stimuli. And the macrophage-derived microvesicles (MMVs) had higher expression levels of several pro-inflammation miRNAs which induced a stronger.inflammatory effect on the recipient cells. Our preliminary microarray data illustrated that the stimulated macrophage-secreted microvesicles (M1 MMVs) had a higher expression level of miR-155 than that of non-stimulated macrophages. Further studies showed that p85α is a primary target of miR-155, and secreted miR-155 in M1 MMVs can enter into adipocytes and effectively reduce p85α expression. So we speculated that miR-155-delivered by M1 MMVs had an effect on insulin resistance of adipocytes by blocking p85α expression. To investigate the function and mechanism of M1 MMVs-mediated miR-155 regulating insulin resistance of human primary adipocytes, we will use the overexpression and interferance technology of miRNA and gene, and perform a variety of molecular biology techniques. Then, we will systematically explain the mechanism of secreted-miRNA involved in insulin resistance. Therefore, the significance of this project is to explore the new mechnism of insulin resistance and will support a new potential RNA-based target for the treatment of insulin resistance and other related metabolic diseases.

最近研究发现，炎性因子刺激下，巨噬细胞分泌的微囊泡(MMVs)中含有大量促炎miRNAs，对其靶细胞有明显促炎效应。我们前期芯片结果显示，炎性巨噬细胞分泌的微囊泡(M1 MMVs)中miR-155的表达显著上调。进一步研究发现，M1 MMVs携带的miR-155进入脂肪细胞，抑制靶基因p85α的表达。由此，我们推测，M1 MMVs可能通过miR-155调控p85α的表达影响脂肪细胞的胰岛素抵抗。本研究拟借助miRNA、基因的过表达和干扰技术及各种分子生物学手段，系统阐明M1 MMVs介导的miR-155对人原代脂肪细胞胰岛素抵抗的作用及其分子机制。本项目有助于进一步了解胰岛素抵抗发生的分子机制，为胰岛素抵抗等相关代谢疾病的治疗提供新的基于RNA治疗的药物靶点。

脂肪组织中M1型巨噬细胞大量积聚是肥胖诱发胰岛素抵抗的主要病理基础。然而，肥胖引发脂肪组织M1型巨噬细胞数量增加的因素以及诱发胰岛素抵抗发生的分子机制，目前尚不十分清楚。作为一种新型细胞间信息转运体，微囊泡（microvesicle, MV）可转运核酸、蛋白、脂质等进入多种受体细胞，通过调控靶基因表达，影响受体细胞的功能。本项目主要研究了微囊泡介导的信号分子在脂肪细胞和巨噬细胞之间的相互转运，调控细胞功能的作用及可能的分子机制。结果发现：1）高脂诱导的肥胖小鼠原代脂肪细胞分泌的微囊泡（HFD ADM）可诱使骨髓来源的巨噬细胞（BMDM）极化为M1型巨噬细胞，对其机制探讨发现HFD ADM可特异性携带miR-155，通过靶向SOCS1调控JAK/STAT通路诱导BMDM极化为M1型巨噬细胞；2）炎性巨噬细胞分泌的微囊泡（M1 MMV）又可通过下调脂肪细胞中磷酸化蛋白激酶B（phosphorylated protein kinase B，pAKT）的表达阻断胰岛素的作用，并且还可抑制脂肪细胞葡萄糖转运蛋白4（glucose transporter type 4，GLUT4）的表达，降低胰岛素刺激的糖转运，诱发胰岛素抵抗。对其机制探讨发现，M1 MMV可能通过激活NF-κB抑制了脂肪细胞胰岛素信号通路转导和胰岛素刺激的糖摄取。本研究一方面首次探究了HFD ADM携带的miR-155对巨噬细胞极化表型的调控作用及分子机制，为肥胖相关炎性、代谢性疾病的防治提供潜在的干预靶点；另一方面首次探讨M1 MMV调控脂肪细胞胰岛素抵抗的可能分子机制，为胰岛素抵抗及相关代谢性疾病的治疗和药物研发提供潜在靶点。