Glial Regulation of Neuronal Physiology in Response to Local Injury

项目摘要 神经系统的局部损伤会导致神经生理学的深远变化，即使在没有受伤的情况下也是如此。 远离损伤部位的神经元。令人惊讶的是，正是这些未受损伤神经元的生理变化，而不是 对受损神经元本身的损害，这是与周围神经病相关的慢性疼痛的原因 在神经损伤后。在创伤性脑损伤后未损伤的神经元中也观察到了这些变化，而且它 已经提出，未受损伤的神经元的生理变化可能是广泛认知的原因 即使是局灶性脑损伤也会导致变化。尽管他们参与了这些重要的进程，但 损伤信号在神经系统中传播的机制还不清楚。 我们最近开发了一种模型，在这种模型中，神经内的神经元可以被稀疏地标记并个别损伤 轴突切断后确定未损伤的神经元。应用此模型在颈椎前神经切断术 果蝇的翅膀，我们发现神经内未受损伤的神经元经历轴突运输的停滞和展示 对刺激反应的活跃度降低。有趣的是，这些效应被证明需要神经胶质信号，证明 这种胶质细胞是受损神经元和生理改变的未受损神经元之间所需的中介细胞。这 该提案将侧重于了解神经胶质细胞是如何感觉到神经元受到损伤的，以及这些细胞是如何以及为什么受到损害的 改变周围神经元的生理学。 在目标1中，我将评估神经胶质细胞识别的足以在回路内广泛调制信号的损伤类型。这就做 还要测试这些信号通路是否与损伤轴突变性所需的信号通路不同。我们有 已经发现，神经胶质细胞需要Draper受体来感知这些损伤反应。在《目标2》中，我将表演 Draper受体的结构功能分析以确定信号所需的功能结构域 受体激活的下游并测试这些结构域下游的信号成分是否 对未损伤的神经元信号进行神经胶质调节所必需的。损伤后神经胶质细胞上的TRAPseq将被用于识别 神经胶质细胞用来与未受损伤的神经元进行交流的其他因素。在目标3中，我将确定为什么胶质细胞可能会导致 通过阻断未损伤的神经元信号和评估神经元的长期恢复来改变未损伤的神经元 神经内的生理学和存活率。 总之，这些研究将提供对伤害信号在神经中传播的机制的洞察。 并确定导致这一未知但重要现象的细胞和分子途径。 这些机制可以作为治疗的靶点，以维持神经胶质细胞清除轴突的有益反应。 损伤后的碎片，但阻止导致未受损伤的神经生理有害变化的信号。这将会 是一种针对损伤后神经病理性疼痛和认知功能障碍的全新方法。

Project Summary Localized damage to the nervous system can lead to far-reaching alterations in neurophysiology, even in uninjured neurons far from the site of injury. Surprisingly, it is these changes in the physiology of uninjured neurons, rather than damage to injured neurons themselves, that is responsible for the chronic pain associated with peripheral neuropathy after nerve injury. These changes have also been observed in uninjured neurons following traumatic brain injury, and it has been posited that physiological changes in uninjured neurons could be responsible for the widespread cognitive changes that result from even focal brain injuries. Despite their involvement in these important processes, the mechanisms by which injury signals spread across the nervous system are poorly defined. We have recently developed a model in which neurons within a nerve can be sparsely labeled and individual injured and uninjured neurons definitively identified after axotomy. Using this model of axotomy in the anterior nerve of the Drosophila wing, we found that uninjured neurons within the nerve undergo stalling of axon transport and exhibit reduced activity in response to stimuli. Interestingly, these effects were shown to require glial signaling, demonstrating that glia are required mediators between injured neurons and the uninjured neurons in which physiology is altered. This proposal will focus on understanding how glia sense that neurons have been injured, and how and why these cells then change the physiology of surrounding neurons. In Aim 1, I will assess what type of injury glia recognize as sufficient to modulate signaling broadly within the circuit. I will also test whether these signaling pathways are distinct from those required for injured axon degeneration. We have already identified that the Draper receptor is required in glia to sense these injury responses. In Aim 2, I will perform a structure function analysis of the Draper receptor to determine which functional domains are required for signaling downstream of receptor activation and test whether the signaling components downstream of those domains are required for glial modulation of uninjured neuron signaling. TRAPseq on glia after injury will be used to identify additional factors that glia use to communicate with uninjured neurons. In Aim 3, I will determine why glia might cause these change in uninjured neurons by blocking uninjured neuron signaling and assessing long-term recovery of neuronal physiology and survival within the nerve. Together, these studies will provide insight into the mechanisms by which injury signals spread across the nervous system and identify the cellular and molecular pathways responsible for this unknown but important phenomenon. These mechanisms could then be targeted therapeutically to maintain beneficial responses of glia in clearing axonal debris after injury, but prevent signaling that leads to detrimental changes in uninjured neuronal physiology. This would be a completely novel approach to targeting neuropathic pain and cognitive dysfunction after injury.