以果蝇为模型研究线粒体铁代谢在帕金森疾病中的作用

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, the detail mechanism of it's pathology remains poorly understood. While the most recognized pathological feature of PD is the preferential loss of dopaminergic (DA) neurons, one of the earlist observations in post mortem PD brains was the accumulation of iron in the substantia nigra (SN). Iron-mediated toxicity may thus contribute to DA neuron dysfunction, but the mechanism has not been established. PINK1 encodes a Ser/Thr kinase involved in Parkinson's disease, and PINK1 loss of function (LOF) affects mitochondrial morphology via a pathway involving Parkin and components of the mitochondrial remodeling machinery. PINK1 loss of function also affects the enzymatic activity of isolated Complex I of the electron transport chain (ETC).However, the primary defect in PINK1 mutants is still unclear. Our previous studies found that overexpression (OE) of mitochondrial iron transpoter mitoferrin (mfrn) or knock down (RNAi) of mitochondrial ferritin (Fer3HCH) both effectively suppressed the abnormal wing posture and flight activity due to PINK1 loss of function, while mfrn RNAi aggravated the pre-existing defects, which indicated a tight relationship between mitochondrial iron metabolism and PINK1, however, the detail mechanism still needs further investigation. Since regulates the expression of mfrn and Fer3HCH both affect the availabe iron content in mitochondria, we hypothesized that the availabe iron content in mitochondria may be responsible for the mfrn and Fer3HCH rescue of PINK1 LOF flies. To complement this study, the present proposal plans to study the mechanism of mitochondrial iron metabolism's effect on Parkinson's disease in drosophila. We want to know more about how mitochondrial iron metabolism regulates the phenotypes of PINK1 loss of function, further more, we also want to investigate the relationship between mitochondrial iron metabolism with Parkin and Rontenone fly model. This will provide valuable clues and theoretical supports for curing Parkinson's disease.

帕金森氏症（PD）是一种神经退行性疾病，其发病机制尚不清楚。PD的主要特征是脑内多巴胺能神经元选择性死亡，并伴随大量铁离子的沉积，但铁离子的沉积与PD的关系仍知之甚少。PINK1是PD的主要致病基因之一，我们的前期研究发现在PINK1缺失的PD果蝇中过表达mfrn或敲低Fer3HCH都能挽救PINK1缺失的表型，而敲低mfrn则加重其表型。调节mfrn和Fer3HCH的表达都能影响线粒体可利用的铁离子水平，因此我们推测：mfrn和Fer3HCH对PINK1缺失表型的影响可能是依赖于线粒体可利用的铁离子水平。本项目计划以果蝇为模型研究mfrn和Fer3HCH在PINK1缺失的PD中的作用，着重探索mfrn和Fer3HCH在PINK1介导的线粒体呼吸和依赖于Parkin的线粒体自噬中的作用，进而阐明线粒体铁代谢与PINK1、Parkin的关系。这对研究PD的致病机理有着至关重要的作用。

PD是一种常见的神经退行性疾病，目前PD的发病机制还尚不清楚，也没有很好的治疗或预防PD的临床药物或方法。临床研究发现，PD病人大脑黑质区常伴随着大量铁离子的沉积，但是铁离子的大量聚集与PD的关系还尚不清楚，有待进一步的研究。果蝇是一种很好的研究PD的模式生物，目前已知的PD致病基因在果蝇中都可以找到同源基因。我们在用果蝇研究PD疾病的发病机制的过程中发现，调节果蝇线粒体铁代谢基因dmfrn和Fer3HCH的表达能显著调节PINK1缺失的PD果蝇模型的异常翅膀形态和飞行能力，这一发现暗示我们线粒体铁代谢与PD疾病之间有着密切的联系。基于以上研究背景，我们在已有的工作基础上，利用果蝇作为模型，结合遗传学、生物化学和分子生物学等多学科的方法和手段，研究了线粒体铁代谢和PD疾病发生发展的关系，主要包括以下两方面的研究：1、线粒体铁代谢基因dmfrn和Fer3HCH在PINK1介导的线粒体呼吸过程中的作用。2、线粒体铁代谢基因dmfrn和Fer3HCH与Parkin的关系。.我们的研究发现：1、调控线粒体铁代谢基因dmfrn和Fer3HCH的表达确实能调控线粒体的铁离子稳态，调节Fer3 HCH或dmfrn的表达都会通过影响线粒体铁离子稳态进而影响dmfrn或Fer3HCH的表达。2、调控线粒体铁代谢基因dmfrn或Fer3HCH的表达确实能影响PINK1缺失的PD果蝇模型的一系列表型，包括：异常翅膀形态、飞行能力、肌肉组织线粒体形态以及线粒体呼吸链复合物I、II、III依赖的呼吸，以及线粒体顺乌头酸酶的活性；3、调控dmfrn或Fer3HCH的表达并不能挽救喂食Rotenone的PD果蝇模型的表型；4、调控dmfrn或Fer3HCH的表达并不能挽救Parkin缺失的PD果蝇模型的表型。这些结果表明调节果蝇线粒体铁代谢可能通过影响线粒体呼吸进而部分挽救PINK1缺失的PD果蝇的表型。我们的研究有利于研究人员进一步探索铁稳态与PD疾病发生发展的关系，并为临床上开发新的预防和治疗PD的药物或方法提供重要线索和理论依据。