The Role of SYNJ1 in Dysregulating the Basal Ganglia Function

项目摘要 受调节的突触传递对于维持大脑的正常功能是必不可少的，而基因突变 突触基因通常与神经和神经退行性疾病有关。这个项目的目标是 揭示突触基因SYNJ1(编码synaptojanin1，synj1)的分子和细胞机制， 导致运动控制的基底节功能障碍。SYNJ1的错义突变(称为 PARK20)与早发性非典型帕金森氏症有关。携带R258Q疾病突变或 SYNJ1基因缺失一个拷贝(SYNJ1/-)表现为运动障碍，突触小泡(SV)循环受损 以及多巴胺能轴突和终末的营养不良改变。然而，synj1部分 功能丧失导致基底节多巴胺能通路的功能障碍仍不清楚。 Synj1是一种富含在轴突终末的肌醇磷酸酶，在那里它调节SV的循环。我们的 初步研究表明，SYNJ1缺乏导致PIP2的中脑特异性变化，异常 突触前钙信号、SV循环受损和中脑神经元突触前终末增大。 我们假设SYNJ1的缺失会扰乱重要的信号脂类，从而导致钙离子的异常 通道功能、多巴胺释放改变和膜转运受损。我们将深入开展一项 表达新近发现的SYNJ1病的SYNJ1基因缺陷小鼠和培养神经元的研究 突变。我们将使用基因编码的钙指示剂和电生理学来分析突触前 钙；免疫化学结合电子显微镜研究膜转运；以及一种新的 光学多巴胺传感器与生化和行为分析相结合检测多巴胺 变速箱。通过实施拟议的研究计划，我们的目标是揭示关键的致病过程 基底节区多巴胺能信号和共同信号的损伤 神经退行性变中其他突触基因共有的通路。这项研究的结果也有望获得 对synj1介导的细胞类型特异性调控的洞察力，并为新的治疗方法提供新的视角。

Project Summary Regulated synaptic transmission is essential in maintaining the proper function of the brain, and mutations in synaptic genes are often linked to neurological and neurodegenerative disorders. The goal of this project is to uncover the molecular and cellular mechanisms of the synaptic gene, SYNJ1 (encoding synaptojanin1, synj1), in contributing to dysfunction of the basal ganglia for motor control. Missense mutations in SYNJ1 (known as PARK20) are associated with early-onset atypical Parkinsonism. Mice carrying the R258Q disease mutation or missing one copy of the SYNJ1 gene (SYNJ1+/-) display motor deficits, impaired synaptic vesicle (SV) recycling and dystrophic changes in dopaminergic axons and terminals. However, the mechanism whereby synj1 partial loss-of-function results in the dysfunction of the dopaminergic pathway in the basal ganglia remains unclear. Synj1 is an inositol phosphatase enriched in the axonal terminals, where it regulates SV recycling. Our preliminary study suggested that SYNJ1 deficiency leads to midbrain-specific changes in PIP2, abnormal presynaptic calcium signals, impaired SV recycling and enlarged presynaptic terminals in the midbrain neurons. We hypothesize that loss of SYNJ1 dysregulates important signaling lipids, which results in aberrant calcium channel function, altered dopamine release and impaired membrane trafficking. We will carry out an in-depth investigation for SYNJ1 deficient mice and cultured neurons expressing recently identified SYNJ1 disease mutations. We will use genetically encoded calcium indicators and electrophysiology to analyze presynaptic calcium; immunochemistry combined with electron microscopy to investigate membrane trafficking; and a novel optical dopamine sensor in combination with biochemical and behavioral analyses to examine dopamine transmission. By implementing the proposed research plan, we aim to reveal key pathogenic processes responsible for the impairment of the dopaminergic signaling in the basal ganglia and common signaling pathways shared by other synaptic genes in neurodegeneration. The result of this study is also expected to gain insights in synj1-mediated cell type-specific regulation and provide new perspectives for novel therapeutics.