MECHANISMS OF NEURONAL DEATH IN PARKINSON'S DISEASE

描述（由申请人提供）：轴突运输受损可能在包括帕金森病（PD）在内的各种神经退行性疾病中起早期关键作用。当轴突运输中断时，营养支持丧失，突触囊泡和递质耗竭，生物物质积累，变性发生，最终神经元死亡。作为病理前兆，轴突转运受损在PD中尤其引人注目，因为突触功能的破坏和轴突病理的存在是一个早期的共同特征。然而，由于缺乏选择性成像和靶向中枢神经系统轴突的工具，这一领域的研究受到限制。为此，我们修改了一个专为外周培养设计的分隔系统，使中枢神经系统神经元可以在轴突分离到屏障一侧的情况下生长。当与gfp标记的来自基因工程小鼠的多巴胺能神经元一起使用时，可以使用活细胞实时成像检查多巴胺能轴突。当前应用的目标是利用我们监测中枢神经系统多巴胺能神经元轴突运输的独特能力来测试一套假设，即pd相关的神经毒素和基因突变触发轴突运输的早期变化，从而导致突触功能丧失和细胞死亡。具体来说，我们假设模拟pd的MPP+影响线粒体和囊泡轴突运输导致突触功能丧失，这是通过线粒体依赖和独立的过程发生的，pd相关基因LRRK2的突变将影响与MPP+类似的细胞器和囊泡运输过程。光学、分子和细胞技术将用于确定多巴胺能轴突中与线粒体和囊泡运动相关的轴突运输和信号通路。这些实验将提供从标准培养或动物模型中无法获得的见解。综上所述，拟议的研究将确定环境或遗传诱导的轴突损伤是否在多巴胺能神经元的死亡中起核心作用。如果是这样，新的治疗方法可以针对阐明的控制点，以阻止或减缓疾病进展。与帕金森病相关的环境或遗传因素可能影响神经元向轴突发送生物材料的基本机制。这可能会损害神经元相互沟通的能力，导致蛋白质和细胞器的积累，最终导致轴突和随后的神经元退化。识别和描述帕金森氏病中轴突损伤的发生方式具有巨大的潜力，可以发现针对已阐明的控制点的新疗法，以阻止或减缓疾病进展。

DESCRIPTION (provided by applicant): Impaired axonal transport may play an early, pivotal role in a variety of neurodegenerative disorders including Parkinson's disease (PD). When axon transport is disrupted, trophic support is lost, synaptic vesicles and transmitters are depleted, biological materials accumulate, degeneration occurs and ultimately the neuron dies. As a pathological precursor, impaired axonal transport is particularly compelling in PD because disruption of synaptic function and the presence of axon pathology is an early, common feature. Research in this area is limited, however, by the lack of tools to selectively image and target CNS axons. Towards this end, we have modified a compartmented system designed for peripheral cultures such that CNS neurons can be grown with axons segregated to one side of a barrier. When used with GFP-labeled dopaminergic neurons derived from genetically engineered mice, dopaminergic axons can be examined using live cell, real time imaging. The goal of the current application is to utilize our unique ability to monitor axonal transport in CNS dopaminergic neurons to test a nested set of hypotheses that PD-associated neurotoxins and genetic mutations trigger early changes in axon transport that contribute to the loss of synaptic function and cell death. Specifically, we hypothesize that the PD-mimetic MPP+ affects mitochondrial and vesicular axon trafficking leading to the loss of synaptic function, that this occurs via mitochondrial-dependent and independent processes, and that mutations in the PD-linked gene LRRK2 will affect similar transport processes of organelles and vesicles as MPP+. Optical, molecular and cellular techniques will be used to determine axonal transport and signaling pathways associated with mitochondrial and vesicular movement in dopaminergic axons. These experiments will provide insights impossible to obtain from standard culture or animal models. Taken together, the proposed studies will determine whether environmentally or genetically induced axonal injury plays a central role in the death of dopaminergic neurons. If so, novel therapies can be targeted to the elucidated control points in order to stop or slow disease progression. PUBLIC HEALTH RELEVANCE Environmental or genetic factors associated with Parkinson's disease may affect fundamental mechanisms underlying the way in which a neuron sends biological materials down an axon. This may compromise the ability of neurons to communicate with each other, lead to the accumulation of proteins and organelles, and ultimately cause the axon and subsequently the neuron to degenerate. Identifying and characterizing how axonal injury occurs in Parkinson's disease has enormous potential for the discovery of novel therapies that can be targeted to the elucidated control points in order to stop or slow disease progression.