MicroRNA29家族在帕金森病认知功能障碍中的作用与机制研究

Cognitive impairment is known to be a common non-motor symptom in individuals with Parkinson’s disease (PD), with unknown etiology and pathogenesis. Several genetic risk factors have already been associated with cognitive dysfunction of PD, indicating genetic factors contribute to progressive cognitive dysfunction. MicroRNAs (miRNAs) are small non-coding RNAs of 20-25 nucleotides and mediate the posttranscriptional gene repression of target RNA transcripts. However, a direct relation between miRNAs and cognitive dysfunction of PD has not yet been established. Our team found serum miR-29s levels were significantly downregulated related to the severity of the cognitive impairment in PD. Besides, we found that miR-29a/miR-29b-1 knock out SH-SY5Y cells resulted in decreased outgrowth of neural processes. Down regulated miR-29a/miR-29b-1 in mice resulted in decreased dendritic spine density in the cortex. So, we speculated that miR-29s may be implicated in the abnormal synapse of cognitive dysfunction of PD. Here we will generate miR-29s knock out cells and mice to further investigate its role in cognitive dysfunction of PD and the specific mechanism. This investigation will be helpful to elucidate the pathologic mechanism of cognitive dysfunction of PD and provide new strategy and therapy target for the disease.

认知功能障碍是帕金森病（PD）常见的非运动症状，其病因和发病机制未明。研究显示异常的基因表达是PD认知障碍潜在的重要病理机制，而微小RNA(miRNA)的表观遗传机制对于基因表达的调控至关重要，尚未有在PD认知障碍中的研究报道。我们前期发现，随着PD患者认知损害程度加重，血清miR-29s水平出现显著下降。miR-29a/miR-29b-1敲除后SH-SY5Y细胞突起显著变短，miR-29a/miR-29b-1缺失突变小鼠的皮层神经元树突棘密度显著降低。因此我们推测：miR-29s在调节神经元骨架、突触结构、功能和高级认知功能中可能具有重要作用，参与到PD认知障碍中的发生和发展。本课题中我们将构建miR-29s条件性敲除的细胞与小鼠模型，研究miR-29s在调控突触中的作用及机制，不仅为PD认知障碍患者找到新的早期生物学标志物，更有助于揭示PD认知障碍的发病机制，并提供可能的治疗靶点。

帕金森病（PD）合并认知功能障碍严重影响PD患者的生活质量，其病因和发病机制未明。研究显示异常的基因表达是PD认知障碍潜在的重要病理机制，而微小RNA（miRNA）的表观遗传机制对于基因表达的调控至关重要。有研究提示MicroRNA29家族（miR-29s）与神经退行性疾病有一定相关性，尚未有在PD认知障碍中的研究报道。我们首先对PD患者血清 miR-29s 表达进行检测，结果显示PD痴呆（PDD）组血清miR-29s家族三个miRNA的水平均显著低于PD正常认知（PD-NC）组，PD轻度认知功能障碍（PD-MCI）组血清miR-29b水平显著低于PD-NC组。使用多元回归模型，血清miR-29b水平仍和PD患者认知水平显著相关且可以准确区别PDD和非PDD（AUC=0.859）。在细胞水平，我们发现miR-29a/b-1 基因缺失（KO）的细胞较正常细胞体积明显增大，24h内的增殖能力显著下降。在动物水平，我们成功建立了miR-29a/ b-1 KO小鼠品系。行为学实验显示miR-29a/b-1 KO小鼠在Y迷宫试验和新物体识别试验中出现明显行为障碍；免疫荧光染色显示miR-29a/b-1 KO小鼠黑质多巴胺能神经元TH的表达较WT组无显著下降，但海马CA3区和纹状体的α-synuclein表达明显高于WT组；HPLC检测提示miR-29a/b-1 KO小鼠纹状体DA、5-HT的含量出现显著性降低。此外，研究发现miR-29a/b-1 KO小鼠黑质区iNOS表达增加，Arg-1表达减少，表明M2型小胶质细胞向M1型小胶质细胞转化，促进脑内的炎症反应。综上所述，我们的研究提示miR-29s是PD认知功能障碍有潜力的生物标志物，有助于进一步揭示PD认知障碍的发病机制，为将来临床治疗PD认知功能障碍提供新的靶点和策略。