miR-663抑制JunB表达调控血管平滑肌细胞表型转化在TAD发生中的作用及机制研究

Thoracic aortic dissection (TAD) is the result of biomechanical weakening of the aortic media and vascular aortic smooth muscle cells (SMCs) phenotypic transition from the contractile to the synthetic type might result in instability of the aortic media, which are responsible for the occurrence of TAD.Recently, we demonstrated that the expression of miR-663 is down-regulated in the aortic SMCs of TAD, and that ectopic expression of miR-663 can induce SMC phenotypic transition from the synthetic to the contractile type in aortic SMCs, indicating that low expression of miR-663 in aortic SMCs may contribute to the development of TAD. In addition, we found that miR-663 significantly inhibited the expression of JunB, which has been shown to play a key role in the regulation of SMC phenotype transition. These data suggest that miR-663 might regulate SMC phenotype transition through the JunB-mediated transcriptional pathway. However, the mechanisms that underlie miR-663 regulation of JunB expression and SMC phenotype transition warrant further investigation. In this application, we propose to elucidate the roles of miR-663/JunB axis in the SMCs phenotypic transition by multiple approaches including bioinformatic analysis, luciferase reporter assay, RNA interference, ChIP, ChIP-chip, and clinical investigation. It's hoped that successful elucidation of the molecular pathways involved in the regulation of the SMCs phenotypic transition in TAD by miR-663 will provide important clues for the development and evaluation of novel therapies against TAD.

动脉平滑肌细胞（SMC）由收缩型向合成型转化所导致的主动脉中层管壁薄弱是胸主动脉夹层(TAD)形成的重要病理基础。尽管目前相关的机制研究已成为该领域的探索热点并取得了明显的进展，但迄今有关miRNA调控SMC表型转化的研究却鲜有报道。我们前期发现miR-663在TAD中膜组织中表达水平显著低于正常组织，细胞学实验显示miR-663可能通过下调JunB表达抑制SMC由收缩型向合成型转变，但具体的作用机制仍有待于明确。本项目拟在此基础上通过荧光素酶报告基因、ChIP-chip、基因芯片检测、生物信息学分析以及相关的细胞功能实验等明确不同环节的作用途径，进而建立起miR-663下调JunB表达抑制SMC由收缩向合成型转化的信号通路。此外，我们还将通过相关的动物模型及临床统计分析评价该通路中的关键基因表达与SMC表型转化及其与TAD发生发展的相关性，为今后开展TAD相关的临床诊疗研究提供理论依据。

血管平滑肌细胞（SMC）由收缩型向合成型转化所导致的主动脉中层管壁薄弱是胸主动脉夹层(TAD)形成的重要病理机制。至今有关miRNA调控SMC表型化的研究却鲜有报道。我们前期发现mi R-663和miR-638在TAD中膜组织中表达水平显著低于正常组织，我们目前发表的工作表明细胞学实验显示人类特异的miRNAs 如miR-663/638及其下游的靶点基因在调节SMC由收缩型向合成型转变的过程中起重要作用，但具体的作用机制仍有待于明确。在国家自然科学基金的赞助下，我们研究了SMC表型转化的调节机理及其与TAD发生发展中的作用。研究表明，miR-663/638及其下游靶点基因如孤儿受体Nur77和NOR1在SMC的增值和分化中起重要作用.重要结果总结如下。.1.miR-663 和miR-638是调节HASMCs的新的调节因子：我们研究表明， 在调节SMC的增值是miR-663和miR-638有明显的协调作用。进一步研究表明，和miR-663一样，在增值的SMC中miR-638的表达明显下降。.2. 高表达miR-638可明显抑制SMC的增值。miR-638的腺病毒(ad-miR-638)可明显增加miR-638在SMC中的表达，抑制PDGF诱导的SMC的增值。我们也发明，miR-638的抑制剂可明显的促进SMC的增值。 CyclinD1是调节SMC增值的重要蛋白。我们发现Cyclin D1 是mir-638的重要靶点。腺病毒介导(ad-miR-638)的miR-638可明显抑制PDGF诱导的CyclinD1的表达，同时我们也发明，miR-638的抑制剂可明显的促进Cyclin D1的表达，提示cyclin D1 在miR-638调节平滑肌细胞的增值中起重要作用。.3.高表达miR-638可明显抑制SMC的迁移。腺病毒介导(ad-miR-638)的miR-638可明显抑制PDGF诱导的SMC的的迁移，提示miR-638在平滑肌细胞的迁移中起重要作用。进一步研究表明，miR-638下游分子NOR1/Nur77是调节平滑肌细胞迁移的重要分子并在体内血栓形成中起关键作用。.4. 发现了miR-663/638 Nur77的激动剂hyperoside.进一步研究表明， Hyperoside对体内血管损伤具有明显的保护作用。