LRRK2基因突变对脑黑质细胞线粒体内铁转运的调控及其在帕金森病超声成像中的实验研究

Parkinson's disease (PD) is a common neurological degeneration disease with high morbidity and mortality. The pathogenesis is unknown. Lacking of effective diagnostic methods may cause the patients lose the best control timing. Recent studies have shown that ultrasound image could display the substantia nigra hyperechogenic (SNH) in the midbrain in 90% of PD patients. The risk of developing to PD in the SNH positive healthy person is 17 times higher than that in SNH negative. So SNH is considered as potential diagnostic bio-markers. The newest study showed the relationship between SNH generation and iron aggregation and metabolic abnormalities. LRRK2 mutation autosomal can significantly increase incidence of substantia nigral iron accumulation and Related to the pathogenesis of PD. LRRK2 protein the G2385R mutation is commonly found in Asian PD patients.So far LRRK2 mutations regulation of iron metabolism signal transduction pathway and mechanism of action has not been elucidated.As the starting point of the relationship of the subject to the the SNH generation with iron metabolism and PD pathogenesis, the study was designed to set up G2385R mutation transgenic mouse model of LRRK2 protein. The purpose is to research the the effect of LRRK2 gene mutation on the nerve cells mitochondria and its effect on the iron transport and metabolism-related molecules in the mouse brain tissue with SNH positive, and to explore the important role of LRRK2 mutation in the the PD development mechanism. A new theoretical basis and candidate targets may be provided for the Pathogenesis and diagnosis of PD Through this study.

帕金森病（PD）是常见的神经退行性变，致死致残率高。临床缺乏有效诊断方法而使患者失去最佳防治时机。最新研究表明超声影像显示的中脑黑质区回声增强（SNH）出现于90%的PD患者，SNH阳性的正常人罹患PD的风险高于SNH阴性者17倍!故SNH是PD潜在的诊断标志。已发现SNH的产生与铁聚集和代谢异常有关，LRRK2常染色体突变通过增加大脑黑质区铁的聚集与PD的发病显著相关，其中LRRK2蛋白G2385R突变常见于亚洲PD患者，目前LRRK2突变与铁代谢相关信号转导通路的调控及作用机理尚未阐明。本课题以SNH与铁代谢的关系为切入点，建立LRRK2蛋白G2385R突变转基因小鼠模型，拟研究出现SNH的鼠脑组织中LRRK2基因突变对神经细胞线粒体的作用及其对铁转运和代谢相关分子的影响，探讨LRRK2基因突变在PD的发生发展中发挥的重要功能，可能为PD的发病机制和诊断提供新的候选靶位和理论依据。

帕金森病（parkinson’s disease, PD）是主要发生于老年人的严重的神经退行性疾病。临床超声影像检查发现约70%的PD患者中脑黒质区会出现片状高回声（SNH，substantia nigra hyperechogenicity），而截至目前SNH的成像机制仍未阐明。本研究应用超声影像检测帕金森病相关转基因模型小鼠LRRK2 G2385R、LRRK2 G2019S、DJ-1 knockout，以及神经毒剂6-OHDA脑立体定位手术偏侧注射构建PD大鼠模型以及加入铁螯合剂Deferiprone和胶质细胞抑制剂Nitidine干预PD模型大鼠，观察各组小鼠以及大鼠的中脑黑质区的回声出现情况以及进行分子生物学实验进一步阐明SNH的形成机制。研究结果发现6-OHDA的PD模型大鼠出现明显的SNH，且范围较大，组织切片后进行特异性铁染色以及免疫荧光染色发现SNH区域有大量三价铁离子聚集和小胶质细胞增生。铁螯合剂Deferiprone和胶质细胞抑制剂Nitidine有明显的神经保护作用，且两种药物都可以显著同时铁离子聚集以及小胶质细胞增生，同时药物干预后6-OHDA PD模型大鼠的SNH面积也显著减小。转基因模型小鼠实验部分，本研究成功构建了LRRK2 G2385R转基因PD小鼠模型，但超声影像检测发现其中脑黒质区未出现SNH，LRRK2 G2019S和DJ-1 knockout转基因PD模型小鼠也未出现SNH现象。以上结果提示SNH与铁离子和胶质细胞增生相关，铁离子的聚集与胶质细胞增生在PD疾病的发生和发展过程中发挥重要作用，该发现不仅为临床提供了有效的诊断途径，同时也为PD致病机理的阐明提供新的检测途径。两种药物Deferiprone和Nitidine都表现出显著的神经保护作用，且都抑制了SNH的出现，提示该两种药物都可以作为临床预防以及治疗PD的选择。而转基因PD模型均没有检测到SNH，原因有待于进一步研究。