Regenerative and degenerative responses to axonal injury

对轴突损伤的再生和退行性反应

• 批准号: 10296110
• 负责人: CATHERINE A COLLINS
• 金额: $ 54.69万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10296110
• 关键词: Address; Adhesives; Alzheimer' s Disease; Animal Model; Axon; Axonal Transport; Behavior; Brain; Categories; Cell Death; Cells; Cytoskeleton; Disease model; Drosophila genus; Drosophila melanogaster; Excision; Future; Genes; Goals; Immune; Immune response; Immune system; Impairment; Individual; Injury; Lead; Light; Mammals; Microglia; Mitogen-Activated Protein Kinases; Modeling; Molecular; Motor Neurons; Mus; Mutation; Nervous System Trauma; Nervous system structure; Neurodegenerative Disorders; Neuromuscular Junction; Neuronal Injury; Neurons; Neuropathy; Organism; Outcome; Pathway interactions; Peripheral; Peripheral nerve injury; Phenotype; Phosphotransferases; Presynaptic Terminals; Process; Public Health; Regulation; RiboTag; Rodent; Signal Pathway; Signal Transduction; Spinal Cord; Stress; Structure; Synapses; Technology; Testing; Therapeutic; Traumatic Brain Injury; Work; axon growth; axon injury; axon regeneration; base; biological adaptation to stress; cell type; chemotherapy; excitotoxicity; experimental study; extracellular; injured; insight; interest; lens; mouse model; nerve damage; nerve injury; neurodegenerative dementia; neuron loss; neuronal circuitry; neurotransmission; painful neuropathy; recruit; regenerative; repaired; response; single-cell RNA sequencing; stroke model

Project Summary/Abstract: Axons form connections between neurons over great distances in the brain and body, hence are vulnerable to damage and stress. This project studies an evolutionarily conserved stress response pathway that becomes activated in multiple scenarios of axonal damage and stress. The pathway, governed by the dileucine zipper kinase DLK, known as Wallenda (Wnd) in Drosophila, engages structural plasticity mechanisms in neurons that allow circuits to adapt to axon damage. These responses include axonal regeneration, neuronal death, and, newly discovered in this project, synapse loss. The long-term goals of this project are (1) to understand the mechanisms that lead to DLK signaling activation, and (2) to understand the cellular pathways that are regulated by DLK. The project combines studies in both Drosophila and mice, focusing on motoneuron (MN) responses to peripheral nerve injury (PNI). For the first goal, Aim 1 tests a hypothesis that DLK/Wnd signaling is restrained by the presence of an intact synaptic connection, hence becomes activated following synapse loss. The experiments build upon observations in complementary paradigms of synapse loss at Drosophila neuromuscular junction (NMJ) synapse: (a) injuries to branched axons demonstrate that only complete removal of all efferent connections are capable of activating Wnd signaling; (b) multiple cytoskeletal mutations that lead to retraction and degeneration of NMJ synapses also lead to Wnd signaling activation. The proposed experiments will distinguish how synaptic interactions intersect with the process of axonal transport to control the activation of Wnd. Aim 2 studies the downstream responses regulated by DLK that enable structural plasticity, and focuses on new phenotypes for DLK in the mouse spinal cord: the loss of synaptic inputs on the cell bodies of axotomized MNs (termed `synaptic stripping') is dependent upon DLK function in MNs. In addition, the recruitment of activated microglia to the MN cell body, which precedes the synapse loss, requires DLK function in axotomized MNs. Aim 2 will test a hypothesis that DLK signaling gates the secretion of molecular signals that recruit specific responses in microglia to facilitate synapse loss. The experiments will evaluate the requirement of candidate secreted and immune molecules that were identified from a RiboTag translational profiling approach to be strong targets of DLK regulation in axotomized MNs. The experiments will also identify the microglial responses gated by DLK in axotomized MNs through single cell RNA-seq of isolated microglia. Taken together, this work is expected to shed new light on neuron-microglial interactions relevant to nervous system injury, and mechanisms structural plasticity and synapse loss through the specific lens of a specific axonal damage signaling pathway.

项目摘要/摘要： 轴突在大脑和身体中远距离的神经元之间形成连接，因此很容易受到 伤害和压力。该项目研究了一条进化上保守的应激反应途径，该途径成为 在轴突损伤和压力的多种情况下被激活。该途径由二亮氨酸拉链控制 激酶 DLK，在果蝇中称为 Wallenda (Wnd)，参与神经元的结构可塑性机制 使电路能够适应轴突损伤。这些反应包括轴突再生、神经元死亡、 并且，在这个项目中新发现的，突触损失。该项目的长期目标是 (1) 了解 导致 DLK 信号激活的机制，以及 (2) 了解细胞通路 受 DLK 监管。该项目结合了果蝇和小鼠的研究，重点关注运动神经元 (MN) 对周围神经损伤（PNI）的反应。对于第一个目标，目标 1 测试 DLK/Wnd 信号传输的假设 受到完整突触连接的限制，因此在突触后被激活 损失。这些实验建立在果蝇突触损失互补范式的观察基础上 神经肌肉接头 (NMJ) 突触：(a) 分支轴突损伤表明，只有完整的突触 移除所有能够激活 Wnd 信令的传出连接； (b) 多种细胞骨架突变 导致 NMJ 突触收缩和退化的因素也会导致 Wnd 信号传导激活。拟议的 实验将区分突触相互作用如何与轴突运输过程相交叉以进行控制 Wnd 的激活。目标 2 研究 DLK 调节的下游反应，使结构 可塑性，并重点关注小鼠脊髓中 DLK 的新表型：突触输入的丧失 轴突化的 MN 的细胞体（称为“突触剥离”）依赖于 MN 中的 DLK 功能。在 此外，在突触丢失之前，将活化的小胶质细胞募集到 MN 细胞体中，需要 DLK 在轴突化的 MN 中发挥作用。目标 2 将检验 DLK 信号传导门控分泌的假设 在小胶质细胞中招募特定反应以促进突触损失的分子信号。实验将 评估从 RiboTag 中识别出的候选分泌分子和免疫分子的需求 翻译分析方法是轴突 MN 中 DLK 调节的强有力目标。实验将 还通过分离的单细胞 RNA-seq 鉴定了轴突化 MN 中 DLK 门控的小胶质细胞反应 小胶质细胞。总而言之，这项工作有望为相关的神经元-小胶质细胞相互作用提供新的线索。 神经系统损伤，以及通过特定透镜的结构可塑性和突触损失的机制 特定的轴突损伤信号通路。