Investigating the Role of LRRK2 Hyperactivity in Autophagic and Synaptic Deficits

项目摘要 帕金森病（PD）是第二大流行的神经退行性疾病，也是最快的- 增长. PD的患病率和严重程度均随年龄增长而增加，预计疾病负担将 随着人口老龄化，未来几十年将急剧增加。目前的治疗方法不能解决 潜在的神经退行性变，以及改进治疗方法的发展受到缺乏理解的阻碍 的发病机制。自噬和突触传递的稳态调节的变化， 不仅与帕金森病有关，还与生理衰老有关。富含亮氨酸重复序列激酶2（LRRK 2）是一种主要的 作为桥接自噬和PD发病机制的联系的候选者。LRRK 2的突变是最常见的 PD的遗传原因，LRRK 2激酶活性增加也与特发性PD有关。有 越来越多的证据表明，多种PD致病途径可能会聚集在破坏自噬上， 依赖于LRRK 2活性的机制。最近，LRRK 2被证明磷酸化Rab的一个子集， GTPases，提供了一个重要的机会， LRRK 2的下游。该提案的目标是阐明LRRK 2在自噬中可能发挥的作用 和突触稳态，在与PD相关的致病性突变的背景下。我们的初步数据 表明LRRK 2中最常见的致病性突变p.G2019S破坏了自噬囊泡（AV） 在啮齿动物和iPSC衍生的人神经元的轴突中的转运。我们假设多种致病性 PD突变通过机制破坏自噬和突触囊泡前体（SVP）转运 依赖于增加的LRRK 2激酶活性。为了验证这一假设，我们将利用iPSC衍生的神经元 作为人类疾病模型。目的1a中提出的实验将探索LRRK 2-p.G2019S是否会导致 AV货物降解的缺陷，作为神经变性的潜在机制。在目标1b中，我们将确定 VPS 35-p.D620N突变，一种增加LRRK 2活性的不同致病性PD突变， 导致与LRRK 2-p.G2019S相似的自噬缺陷。最后，在目标2中，我们将探讨SVP是否 从索马到轴突的转运受到导致LRRK 2过度活跃的突变的损害， 突触稳态的分支总的来说，我们希望这些目标将有助于阐明机制 PD的多种原因可以聚集在LRRK 2依赖性途径上，以破坏神经元自噬 和突触稳态此外，这项工作可以为未来的工作提供基础，以阐明 在没有衰老疾病的情况下，生理衰老改变这些过程的途径。到 作为研究计划的补充，全面的培训计划将帮助受训者满足特定的研究要求。 目标、专业目标（包括写作、指导和演示）和临床目标（结合在一起 一个综合的医生-科学家培训途径），所有这些都在一个支持性的、协作性的科学环境中进行。

PROJECT SUMMARY Parkinson’s disease (PD) is the second-most prevalent neurodegenerative disease and the fastest- growing. PD increases in both prevalence and severity with age, and the disease burden is projected to dramatically increase in coming decades as the population ages. Current therapies do not address the underlying neurodegeneration, and development of improved therapeutics is hindered by poor understanding of the pathogenesis. Changes in homeostatic regulation of both autophagy and synaptic transmission have been implicated in not only PD but also physiological aging. Leucine-rich repeat kinase 2 (LRRK2) is a leading candidate for a nexus bridging autophagy and PD pathogenesis. Mutations in LRRK2 are the most common genetic cause of PD, and increased LRRK2 kinase activity has also been linked to idiopathic PD. There is accumulating evidence that multiple PD-causative pathways may converge on disrupting autophagy through mechanisms dependent on LRRK2 activity. Recently, LRRK2 was shown to phosphorylate a subset of Rab GTPases, providing an important opportunity to make advances in the understanding of mechanisms downstream of LRRK2. The goal of this proposal is to elucidate the role that LRRK2 may play in autophagy and synaptic homeostasis, in the context of pathogenic mutations associated with PD. Our preliminary data suggests that the most common pathogenic mutation in LRRK2, p.G2019S, disrupts autophagic vesicle (AV) transport in the axons of rodent and iPSC-derived human neurons. We hypothesize that multiple pathogenic PD mutations disrupt autophagy and synaptic vesicle precursor (SVP) transport through mechanisms dependent on increased LRRK2 kinase activity. To test this hypothesis, we will exploit iPSC-derived neurons as a human disease model. Experiments proposed in Aim 1a will explore whether LRRK2-p.G2019S causes deficits in AV cargo degradation, as a potential mechanism of neurodegeneration. In Aim 1b, we will determine whether the VPS35-p.D620N mutation, a different pathogenic PD mutation that increases LRRK2 activity, causes similar autophagy deficits as LRRK2-p.G2019S. Finally, in Aim 2, we will explore whether SVP transport from the soma to the axon is impaired by mutations causing LRRK2 hyperactivity, with potential ramifications for synaptic homeostasis. Collectively, we expect that these Aims will help elucidate mechanisms by which multiple causes of PD can converge on a LRRK2-dependent pathway to disrupt neuronal autophagy and synaptic homeostasis. Additionally, this work may provide a foundation for future work to shed light on pathways by which physiological aging alters these processes in the absence of diseases of aging. To complement this research plan, a comprehensive training plan will help the trainee meet specific Research Goals, Professional Goals (including writing, mentoring, and presentation), and Clinical Goals (tying together an integrated physician-scientist training pathway), all in a supportive, collaborative scientific environment.