基于Nurr1基因的帕金森病发病机制研究

Parkinson disease (PD) is the second most common neurodegenerative disease in adult mainly manifesting movement disorder symptoms. The loss of dopamine (DA) neurons in the substantia nigra (SN) is the pathological hallmark of PD. Although many PD related genes and enviormental factors have been identified, the mechanisms underlying the loss of DA neurons in PD are still poorly understood. Previously we have documented that Nurr1, a gene regulating DA neuron differentiation is a risk factor for PD. Our recent works have found that down-regulation of Nurr1 can cause DA neuron degeneration, increase α-synuclein expression, and induce glia-mediated inflammation and neuronal injury. Therefore, we believe that Nurr1 may play an important role in the development of PD. In this project, we plan to use conditional knock-out Nurr1 mice (1) to investigate the pathological process; (2) to study the Nurr1-mediated inflammation and neuronal injury; (3) to use Nurr1 knock-out mice and α-synuclein gene transgenic mouse and cell models to determine the interaction and underlying mechanisms of Nurr1 and α-synuclein; (4) we will measure Nurr1, and related factors in the CSF of PD patients and evaluate if alterations of these proteins levels are associated with the disease course of PD. The outcome of this project will have important scientific significance and clinical value.

帕金森病(PD)是一组以运动障碍为主的黑质多巴胺(DA)神经变性疾病，发病机制尚未明了。我们首先报道，控制DA神经分化的基因Nurr1是PD的危险因子；随后研究发现Nurr1的下调会引起DA神经变性；Nurr1与PD致病基因α-syn有相互作用；另外，Nurr1还参与了胶质细胞介导的DA神经炎性损伤。我们认为Nurr1在PD的发病过程中起了重要作用。本课题我们将深入探讨Nurr1的PD发病机制，通过我们建立的条件敲除Nurr1小鼠(1)研究黑质-纹状体进行性变性的病理过程;(2)明确Nurr1参与炎性损伤DA神经的机制和调控;(3)应用α-syn过表达和Nurr1敲除小鼠及细胞模型，揭示α-syn与Nurr1的相互作用和机制;(4)临床上测定PD病人脑脊液Nurr1及相关因子浓度，论证这些蛋白的变化是否与PD的发生和发展相关。本研究结果对阐明PD的发病机制具有重要的科学意义和临床价值。

帕金森病（PD）是最常见的神经退行性疾病之一，中脑黑质多巴胺（DA）神经元进行性变性是最主要的病理改变。帕金森病的发病机制尚未明了，我们首先报道控制DA神经分化的基因Nurr1是PD的危险因子，Nurr1的下调会引起DA神经变性。Nurr1参与了胶质细胞介导的DA神经炎性损伤，同时与PD致病基因α-突触核蛋白（α-syn）有相互作用。在本项目中，我们深入探讨了基于Nurr1基因的PD发病机制：（1）完成了中脑DA神经Nurr1和Nurr1协同基因Pitx3特异性敲除小鼠模型的建立，发现成年小鼠逐步敲除DA细胞的Pitx3基因会引起进行性的黑质纹状体DA神经系统变性，且导致Nurr1蛋白表达下降，证明Nurr1基因对于DA神经系统的重要作用。（2）构建了小胶质细胞Nurr1条件性敲除小鼠模型，验证了敲除小胶质细胞中Nurr1会促进炎性反应，但还不足以引发神经元损伤。对该小鼠模型进行外周LPS慢性刺激，发现转棒运动能力降低，神经炎性表达增加，并出现了黑质DA神经元死亡。（3）构建了野生型α-syn（WT）和引起聚集的突变型α-syn（A53T）的稳转细胞，进一步验证了α-syn（WT和A53T）对Nurr1下游多巴胺神经细胞基因的调控作用。α-syn的过表达降低了Nurr1启动子的转录活性，并且α-syn（WT和A53T）介导的Nurr1改变主要是通过其对NF-κB核蛋白水平的调节来实现的。（4）在PD病人脑脊液中证明了特异miRNA表达谱并发现了Nurr1相关基因LAG-3可作为PD潜在生物标志物。在PD病人外周血中证明了Nurr1及相关炎症因子的表达变化，从而在临床水平上验证了Nurr1可能通过抑制炎症反应在PD的病理过程中发挥作用。还进行了帕金森病患者尸检标本的迷走神经和肠道神经炎症病理分析。以上研究结果对阐明基于Nurr1的PD的发病机制具有重要的科学意义和临床价值。