Investigating novel mechanisms that underlie glial-mediated synapse elimination in development and aging

项目摘要 在适当的神经元伙伴之间形成和维持突触连接对于 神经系统功能正常。事实上，无论是在最初的突触形成中还是在随后的突触形成中 发育性突触消除是许多神经发育障碍的基础。突触消除 发生在适当的发育背景之外是与年龄相关的突触丢失的基础 认知功能减退和神经退行性疾病。因此，定义了作为监管基础的机制 将提供对发育过程中如何形成适当连接的洞察，以及 这些突触消除的病理过程。 尽管它在整个生命的神经系统发育和功能中起着至关重要的作用，但我们仍然知之甚少 这一过程背后的机制。然而，我们确实知道，神经胶质是必需的。为了辨别小说 突触发育的神经胶质调节因子，我完成了对果蝇的正向遗传筛查，并鉴定出91 当在胶质细胞中被击倒时，改变突触数量的分子。在这些分子中有一种是免疫 受体CRQ，我发现它是在发育过程中神经胶质消除突触所必需的。这项提案将把重点放在 了解CRQ在突触消除中的作用，以便洞察其中更大的问题 突触经历发育性突触消除，其特殊性背后的机制 过程，以及这些相同的机制是否在与衰老相关的病理性突触丢失中重复使用。 目标1将解决哪些突触在神经中经历发育消除的问题 系统并评估其中哪些是依赖于CRQ的。我最近开发了一种可诱导的突触前 使这项工作成为可能的标记，并将产生可诱导的突触后标记作为这一目标的一部分。目标2将 使用邻近标记识别CRQ的神经元配体(S)，该配体负责指定哪些突触经历 消除，并将确定这些配体的表达和定位是如何调控的。目标3将定义 哪些突触随着年龄的增长而丢失，并确定CRQ是否作为突触丢失的常见中介。 发育和衰老。我还将根据最近的转录特征进行有针对性的筛选 实验I完成了识别与年龄相关的突触丢失的其他神经胶质调节因子。 总而言之，这些研究将解决突触被靶向消除的机制以及如何消除。 这是实现更大目标的一个关键问题，即了解神经元和胶质细胞是如何协同工作的 在一生中创造并保持适当的突触连接。剖析这些机制还将 提供与年龄相关的突触丢失过程的洞察力，这是年龄相关认知能力下降的基础。在……里面 此外，执行这项工作将使我能够解决我的技术技能方面的现有差距，这将使我能够 作为一名独立的调查者执行我的长期研究目标。

Project Summary Formation and maintenance of synaptic connections between appropriate neuronal partners is essential for proper nervous system function. Indeed, impairments in either initial synapse formation or in subsequent developmental synapse elimination underlie many neurodevelopmental disorders. Synapse elimination that occurs outside of appropriate developmental contexts underlies synaptic loss associated with age-related cognitive decline and in neurodegenerative diseases. Thus, defining the mechanisms that underlie the regulation of synapse number will provide insight into how appropriate connections are formed during development, and these pathologies of synapse elimination. Despite its essential role in nervous system development and function throughout life, we still know little about the mechanisms underlying this process. We do know, however, that glia are required. In order to identify novel glial regulators of synapse development, I completed a forward genetic screen in Drosophila, and identified 91 molecules that, when knocked down in glia, alter synapse number. Among these molecules is the immune receptor Crq, which I found is required for glial elimination of synapses in development. This proposal will focus on understanding Crq’s role in synapse elimination, in order to gain insight into the larger questions of which synapses undergo developmental synapse elimination, the mechanisms underlying the specificity of this process, and whether these same mechanisms are re-used in pathological synapse loss associated with aging. Aim 1 will address the question of which synapses undergo developmental elimination across the nervous system and evaluate which of these are Crq-dependent. I have recently developed an inducible pre-synaptic label that makes this work possible, and will generate inducible postsynaptic labels as part of this aim. Aim 2 will use proximity labeling to identify the neuronal ligand(s) for Crq that act to specify which synapses undergo elimination, and will identify how expression and localization of these ligands are regulated. Aim 3 will define which synapses are lost with aging, and identify whether Crq acts as a common mediator of synaptic loss in development and aging. I will also perform a targeted screen based on a recent transcriptional profiling experiment I completed to identify additional glial regulators of age-related synaptic loss. Together, these studies will address the mechanisms by which synapses are targeted for elimination and how. This is a key question in achieving the larger goal of understanding how neurons and glia work together to create and maintain appropriate synaptic connections throughout life. Dissecting these mechanisms will also provide insight into the process of age-related synaptic loss that underlies age-related cognitive decline. In addition, performing this work will allow me to address existing gaps in my technical skills that will allow me to carry out my long-term research goals as an independent invesitigator.