Cellular Functions of Parkin

描述（由申请人提供）：parkin突变是隐性遗传性帕金森病（PD）的最常见原因。虽然parkin在包括大脑在内的许多组织中表达，但其突变与黑质多巴胺能（DA）神经元的特异性变性和帕金森病有关。我们的长期目标是了解parkin的功能及其在帕金森病中DA神经元选择性变性中的作用。使用parkin基因敲除小鼠和果蝇的研究表明，parkin基因的缺失会破坏线粒体功能。另一方面，对PD神经毒素的研究已经证明了线粒体功能障碍在PD发病机制中的关键作用。因此，我们将能够通过研究parkin如何影响线粒体功能来深入了解帕金森病的分子机制。我们以前的研究表明，帕金通过抑制单胺氧化酶（MAO）的转录来减弱胞质多巴胺的毒性，MAO是负责多巴胺氧化脱氨的线粒体酶。我们的初步研究表明，parkin与转录因子雌激素相关受体1（ERR1）相互作用，ERR1在包括MAO在内的许多线粒体蛋白的转录调控中起重要作用。此外，我们发现细胞色素C氧化酶亚基4的同种型2（也称为COX 412）的表达与细胞色素C氧化酶亚基4的表达相关。复合物IV），以类似的方式被parkin抑制。我们的微阵列研究还表明，帕金改变了许多由核基因组编码的线粒体蛋白质的表达。基于这些证据，我们假设帕金调节许多核编码的线粒体蛋白质的转录，通过与线粒体基因表达中关键参与的转录因子相互作用。我们将通过研究parkin如何调节单胺氧化酶和COX4i2的表达来验证这一假设，并检查parkin对其他线粒体蛋白表达的影响。为了研究parkin在体外和体内的细胞功能，我们将使用细胞系、parkin转基因小鼠、parkin敲除小鼠和来自具有parkin突变的PD患者的细胞。从这项研究中获得的知识将大大促进我们对parkin如何影响线粒体功能以及当parkin突变时这种调节如何出错的理解。它将为parkin突变导致帕金森病的机制提供新的见解。公共卫生相关性这项提案产生的结果将大大提高我们对parkin的理解，parkin是一种与早发性帕金森病相关的基因。我们的研究还将为开发更有效的帕金森病疗法提供新的靶点。

DESCRIPTION (provided by applicant): Mutations of parkin represent the most frequent cause of recessively-inherited Parkinson's disease (PD). Although parkin is expressed in many tissues including the brain, its mutations are linked to specific degeneration of nigral dopaminergic (DA) neurons and Parkinson's disease. Our long-term goal is to understand the function of parkin and its role in the selective degeneration of DA neurons in Parkinson's disease. Studies using parkin knockout mice and flies showed that loss of parkin disrupts mitochondrial functions. On the other hand, research on PD neurotoxins has demonstrated a critical role of mitochondrial dysfunction in PD pathogenesis. Thus, we would be able to gain significant insights into the molecular mechanism of Parkinson's disease by studying how parkin affects mitochondrial functions. Our previous studies have shown that parkin attenuates the toxicity of cytosolic dopamine by suppressing the transcription of monoamine oxidases (MAO), which are mitochondrial enzymes responsible for the oxidative deamination of dopamine. Our preliminary studies showed that parkin interacted with the transcription factor Estrogen-Related Receptor 1 (ERR1), which plays a significant role in transcription regulation of many mitochondrial proteins including MAO. Furthermore, we found that expression of COX4i2, isoforms 2 of subunit 4 of cytochrome C oxidase (a.k.a. Complex IV), was suppressed by parkin in a similar manner. Our microarray studies also showed that parkin altered the expression of many mitochondrial proteins encoded by the nuclear genome. Based on these lines of evidence, we hypothesize that parkin regulates the transcription of many nuclear-encoded mitochondrial proteins by interacting with transcription factors critically involved in mitochondrial gene expression. We will test this hypothesis by studying how parkin regulates the expression of monoamine oxidases and COX4i2, and examining the effects of parkin on the expression of other mitochondrial proteins. To investigate the cellular functions of parkin both in vitro and in vivo, we will use cell lines, parkin transgenic mice, parkin knockout mice, and cells derived from PD patients with parkin mutations. Knowledge gained from this study will significantly advance our understanding on how parkin affects mitochondrial functions and how such regulation goes awry when parkin is mutated. It will provide novel insights into the mechanisms by which mutations of parkin cause Parkinson's disease. PUBLIC HEALTH RELEVANCE Results generated from this proposal would significantly improve our understanding of parkin, a gene linked to early-onset Parkinson's disease. Our studies will also provide novel targets for the development of more effective therapies for Parkinson's disease.