Neuroprotective mechanism of DJ-1 in Parkinson's disease

描述（由申请人提供）：最近在常染色体隐性形式的帕金森病（PD）中发现了DJ-1的功能丧失突变。DJ-1在正常和病理状态中的作用尚不清楚，其推测功能的证据也颇有争议。DJ-1在保护神经元免受氧化应激中的作用，对于理解这种遗传形式的帕金森病和散发性帕金森病的细胞死亡的潜在共同机制具有重要意义，而散发性帕金森病被认为是由线粒体功能障碍产生的氧化应激引起的。虽然DJ-1缺陷细胞更容易受到氧化应激的影响，但DJ-1似乎没有直接清除活性氧（ROS）的作用。相反，DJ-1可能在ROS的下游途径上起作用。具体来说，DJ-1可能在泛素化中起重要作用，而DJ-1缺失的小鼠大脑在氧化应激反应中泛素化增加。DJ-1也被证明具有伴侣功能。DJ-1在氧化应激下变成酸性。为了研究DJ-1缺乏导致帕金森病的发病机制，我们成功培育了DJ-1缺失小鼠。我们的初步研究表明，dj -1缺失小鼠出现与多巴胺神经传递改变相关的年龄依赖性运动缺陷，与多巴胺转运蛋白（DAT）功能异常一致。基于这些观察结果，我们假设DJ-1促进了靶蛋白如DAT的泛素化和随后的降解，并且该功能被氧化应激激活。我们提出以下实验来验证这些假设，并确定DJ-1在维持最佳多巴胺传递和细胞存活中发挥作用的靶分子和途径。目的1。探讨dj -1缺失小鼠多巴胺神经元是否更容易受到衰老和百草枯的攻击。我们将研究衰老和百草枯处理对dj -1缺失小鼠的生化、行为和解剖特性的影响。目标2。探讨氧化应激下DJ-1是否影响泛素蛋白酶体途径。我们将检测总泛素化蛋白水平，并比较dj -1缺失和WT脑中涉及多巴胺能神经元死亡的特定底物蛋白的相对水平。此外，我们将通过测量其表面表达和泛素化来研究DJ-1对泛素-蛋白酶体系统的影响如何改变DAT功能。目标3。探讨DJ-1的伴侣蛋白功能及其氧化依赖性与泛素通路的协同作用。了解DJ-1的神经保护功能有助于合理治疗帕金森病，预防其表现或进展。由于帕金森病在很大一部分老年人口中导致严重残疾，因此这些发现将对公共卫生产生重大影响。

DESCRIPTION (provided by applicant): Loss-of-function mutations in DJ-1 were recently identified in an autosomal recessive form of Parkinson's disease (PD). The role of DJ-1 in normal and pathological states is still unclear, and evidences for its putative functions have been quite controversial. The role of DJ-1 in protecting neurons from oxidative stress is particularly informative in understanding a potential common mechanism for cell death in this genetic form of Parkinson's disease and in sporadic forms of Parkinson's disease which is thought to result from oxidative stress generated by mitochondrial dysfunction. Although DJ-1 deficient cells are more susceptible to oxidative stress, DJ-1 does not seem to have direct scavenging effect of reactive oxygen species (ROS). Instead, DJ-1 may work on a downstream pathway from ROS. Specifically, DJ-1 may be important in ubiquitination and DJ-1-null mouse brain attenuated increase in ubiquitination in response to oxidative stress. DJ-1 has been also shown to have chaperone function. DJ-1 changes into an acidic form under oxidative stress. To investigate the pathogenesis of Parkinson's disease caused by DJ-1 deficiency, we have successfully generated DJ-1-null mice. Our preliminary studies indicate that DJ-1-null mice develop age-dependent motor deficits associated with alteration of dopamine neurotransmission, consistent with hyperactive dopamine transporter (DAT) function. Based on these observations, we hypothesize that DJ-1 facilitates ubiquitination and subsequent degradation of target proteins such as DAT and this function is activated by oxidative stress. We propose the following experiments to test these hypotheses and identify the target molecules and pathways in which DJ-1 plays a role to maintain optimal dopamine transmission and cell survival. Aim 1. To investigate whether dopamine neurons in DJ-1-null mice are more vulnerable to aging and paraquat challenge. We will examine the effect of aging and paraquat treatment in DJ-1-null mouse for its biochemical, behavioral and anatomical properties. Aim 2. To investigate whether DJ-1 influences the ubiquitin proteasomeal pathway under oxidative stress. We will examine the total ubiquitinated proteins levels and compare the relative levels of specific substrate proteins implicated in dopaminergic neuronal death in DJ-1-null and WT brains. In addition, we will examine how the effect of DJ-1 on ubiquitin-proteasome system alters DAT function by measuring its surface expression and ubiquitination. Aim 3. To investigate the chaperone function of DJ-1 and its oxidation dependent cooperation with ubiquitin pathway. Relevance Understanding the neuroprotective function of DJ-1 may lead to rational therapy for Parkinson's disease to prevent the manifestation or progression. Since Parkinson's disease leads to significant disability in a significant portion of the elderly population, such findings will have a significant impact in public health.