Mechanisms of Synaptic Specificity in C. elegans

线虫突触特异性的机制

• 批准号: 8217129
• 负责人: KANG SHEN
• 金额: $ 33.79万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-07 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8217129
• 关键词: Alzheimer' s Disease; Axon; Axonal Transport; Brain; CDC2 Protein Kinase; Caenorhabditis elegans; Chemical Synapse; Communication; Cues; Cyclin-Dependent Kinases; Cyclins; Data; Dendrites; Development; Disease; Distal; Event; Feedback; Genetic; Genetic Screening; Grant; Guanosine Triphosphate Phosphohydrolases; Health; Kinesin; Light; Lobular Neoplasia; Location; Mediating; Microtubules; Modeling; Modification; Molecular; Molecular Motors; Motor; Neurodegenerative Disorders; Neurons; Pathogenesis; Pathway interactions; Pattern; Physiological; Presynaptic Terminals; Property; Proteins; Proteomics; Publishing; Recruitment Activity; Regulation; Research; Specific qualifier value; Specificity; Stereotyping; Structure; Synapses; Synaptic Vesicles; System; Testing; Transport Vesicles; Vesicle; base; extracellular; gene function; in vivo; insight; mutant; neuronal cell body; presynaptic; relating to nervous system; synaptogenesis; trafficking

DESCRIPTION (provided by applicant): Chemical synapses are specialized cellular junction structures that are essential for communication between neurons. During development, synapses form between specific neurons at defined subcellular compartments. Synaptic target selection, axonal transport and presynaptic assembly are integral steps of synapse formation that are poorly understood. Here, I propose to expand our research to understand two essential aspects of synapse formation: polarized axonal trafficking and how aggregation of active zone proteins is regulated. Synapses are usually formed on distal axon and dendrites, creating a challenging problem for effective exchange of intracellular material between cell bodies and synapses. Microtubules and MT associated motors mediate intracellular trafficking. It is generally believed that the direction of transport depends on two factors: the polarity of MTs and the type of motor involved. Based on our published and unpublished data, we have identified two cyclin-dependent kinase pathways that are essential for the trafficking of presynaptic components. In the absence of both pathways, the vast majority of synaptic vesicle proteins and active zone markers fail to localize to axon and instead are found in dendrites due to misregulation of kinesin motors. Another poorly understood question in synapse formation is how the pool size of synaptic vesicles is determined. Many synapses display stereotyped size of synaptic vesicle clusters, suggesting that molecular mechanisms regulate the assembly of synaptic vesicle precursors locally at the presynaptic terminals. When the appropriate number of vesicles is recruited, there might be a negative feedback system to shut down the assembly pathway. We reasoned that if this feedback mechanism is defective, one should expect to see mutant synapses with abnormal vesicle pool. Indeed in a forward genetic screen, we isolated a mutant in which the proximal synapses are abnormally large while the distal synapses contain little material. We have also identified an Arf like GTPase to be responsible for the regulation the location and size of presynaptic specializations. To gain mechanistic insights on the functions of these genes, I specifically plan to understand: 1) how the cyclin-dependent kinases pathways control axonal transport and synapse localization through the regulation of molecular motors, and 2) how an ARF like GTPase, ARL8 regulate the synaptic vesicle pool size and presynaptic assembly. Given that many neural disorders are associated with alterations in synaptic connectivity and that cyclin dependent kinases have been implicated in neurodegenerative diseases, it is hopeful that this project will help to understand brain development under both physiological and pathological conditions. PUBLIC HEALTH RELEVANCE: Synapses are critical for the communication between neurons. During synapse formation, proteins and vesicle are transported to presynaptic terminals in distal axons. The proposed study characterizes critical regulatory mechanisms for trafficking synaptic components to axons as well as locally synaptic assembly. This project will potentially shed light on the pathogenesis mechanisms of neurodegenerative diseases such as the Alzheimer's disease.

描述（由申请人提供）：化学突触是特殊的细胞连接结构，对于神经元之间的通信至关重要。在发育过程中，突触在特定的亚细胞区室的特定神经元之间形成。突触目标选择、轴突运输和突触前组装是突触形成的重要步骤，但人们对此知之甚少。在这里，我建议扩大我们的研究，以了解突触形成的两个重要方面：极化轴突运输以及活性区蛋白聚集的调节方式。 突触通常形成于远端轴突和树突上，这给细胞体和突触之间有效交换细胞内物质带来了挑战性的问题。微管和 MT 相关马达介导细胞内运输。人们普遍认为，运输方向取决于两个因素：MT 的极性和所涉及的电机类型。根据我们已发表和未发表的数据，我们已经确定了两种对于突触前成分的运输至关重要的细胞周期蛋白依赖性激酶途径。在缺乏这两种途径的情况下，绝大多数突触小泡蛋白和活性区标记物无法定位于轴突，而是由于驱动蛋白马达的失调而在树突中发现。突触形成中另一个鲜为人知的问题是突触囊泡池的大小是如何确定的。许多突触显示出突触小泡簇的固定大小，这表明分子机制在突触前末端局部调节突触小泡前体的组装。当招募适当数量的囊泡时，可能会出现负反馈系统来关闭组装途径。我们推断，如果这种反馈机制有缺陷，人们应该会看到具有异常囊泡池的突变突触。事实上，在正向遗传筛选中，我们分离出了一种突变体，其中近端突触异常大，而远端突触含有很少的物质。我们还发现了像 GTPase 一样的 Arf 负责调节突触前特化的位置和大小。 为了深入了解这些基因的功能，我特别计划了解：1）细胞周期蛋白依赖性激酶通路如何通过分子马达的调节来控制轴突运输和突触定位，2）GTPase、ARL8等ARF如何调节突触小泡池大小和突触前组装。鉴于许多神经疾病与突触连接的改变有关，并且细胞周期蛋白依赖性激酶与神经退行性疾病有关，因此该项目有望有助于了解生理和病理条件下的大脑发育。 公共卫生相关性：突触对于神经元之间的通信至关重要。在突触形成过程中，蛋白质和囊泡被运输到远端轴突的突触前末梢。拟议的研究描述了将突触成分运输到轴突以及局部突触组装的关键调节机制。该项目将有可能揭示阿尔茨海默病等神经退行性疾病的发病机制。