Do somatosensory endings use axonal or dendritic regeneration pathways?

体感末梢使用轴突或树突再生途径吗？

• 批准号: 8807538
• 负责人: Melissa Rolls
• 金额: $ 22.85万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8807538
• 关键词: Action Potentials; Affect; Afferent Neurons; Amputation; Animals; Axon; Axotomy; Back; Biological Assay; Blood Glucose; Cancer Patient; Cells; Cellular biology; Characteristics; Counseling; Cutaneous; Dendrites; Development; Drosophila genus; Esthesia; Exhibits; Fire - disasters; Foundations; Free Nerve Ending; Future; Image; Injury; Lasers; Left; Life; MAP Kinase Kinase Kinase; MAP Kinase Modules; Maintenance; Mediating; Medical; Methodology; Methods; Microtubules; Modeling; Molecular; Morphology; Natural regeneration; Nature; Nervous system structure; Neurites; Neurons; Numbness; Organism; Pain; Pathway interactions; Patients; Peripheral; Peripheral Nervous System Diseases; Physiological; Play; Plus End of the Microtubule; Process; Reporter; Role; Sensory; Signal Transduction; Skin; Spinal Ganglia; Staging; Structure; Synaptic Transmission; Temperature; Testing; Time; Touch sensation; Transcription Factor AP-1; United States National Institutes of Health; Vertebrates; Work; Zebrafish; axon regeneration; cell injury; chemotherapy; diabetic; ganglion cell; injured; knock-down; neural circuit; neuronal cell body; novel; public health relevance; regenerative; repaired; research study; response; response to injury; sensory mechanism; sensory stimulus; somatosensory; transcription factor

DESCRIPTION (provided by applicant): Sensory neurons that innervate the skin are easily damaged. When damage exceeds the capacity of these cells for repair, peripheral neuropathy (PN) manifests. Cancer patients who survive chemotherapy, or diabetics who struggle to control blood sugars, may be left with months to a lifetime of numbness or shooting pain. Free nerve endings in the skin mediate pain and temperature sensation, both of which are compromised early in most forms of PN. The repair mechanism of these sensory endings has not been elucidated, although it is the key to understanding the onset of PN and may also be critical for developing strategies to delay or cure PN. Axon regeneration uses a common set of machinery in all organisms and neurons in which it has been studied. This core machinery includes a MAP kinase cascade initiated by DLK and the activation of AP-1 transcription factors. This core pathway mediates regeneration when axons of sensory neurons in Drosophila are injured, but regeneration of peripheral sensory endings in the same cells is completely independent of this machinery. In Drosophila, sensory endings have been defined as dendrites by cell biology studies, suggesting that the DLK pathway may be specific to axon regeneration and not used for dendrite regeneration. Determining whether sensory endings in vertebrates are repaired using the conserved axon regeneration pathway or a completely unexplored dendrite regeneration pathway will be a critical foundation for understanding PN. In this exploratory work, two major lines of experimentation will be used to determine the repair pathway used to regenerate vertebrate sensory endings in the skin. The sensory neurons that innervate the skin in zebrafish will be used as a model for all of these experiments. Zebrafish larval sensory neurons known as Rohon-Beard (RB) neurons are accessible for imaging and manipulation with current methodology, so these cells will be used as a first model in which to study sensory ending cell biology and injury responses. Analogous methods will then be developed for dorsal root ganglion neurons (DRGs), as these are the most relevant for understanding PN. To determine whether vertebrate free sensory endings are dendrites as in Drosophila, or axons as they are historically classified in vertebrates, we will determine the polarity of their microtubules. All known dendrites contain at least 50% minus-end-out microtubules while axons are close to 100% plus-end-out. Microtubule polarity has never been assayed in vertebrate sensory endings, so this will be done in both RB and DRG cells. To determine whether injury to sensory endings triggers the identified axon regeneration pathway or a novel dendrite regeneration pathway, we will develop markers for DLK signaling and compare responses to central axon injury and peripheral sensory ending injury in zebrafish sensory neurons. These two lines of experimentation will form a foundation for understanding how sensory endings are repaired, and how this process fails in patients with PN.

描述（由申请人提供）：神经支配皮肤的感觉神经元容易受损。当损伤超过这些细胞的修复能力时，就会出现周围神经病变（PN）。化疗后幸存下来的癌症患者，或努力控制血糖的糖尿病患者，可能会留下数月至一生的麻木或刺痛。皮肤中的游离神经末梢介导疼痛和温度感觉，这两者在大多数形式的PN中早期受到损害。这些感觉末梢的修复机制尚未阐明，尽管它是理解PN发病的关键，也可能是制定延迟或治愈PN的策略的关键。轴突再生在所有生物体和神经元中使用一套共同的机制，它已经被研究过。该核心机制包括由DLK启动的MAP激酶级联和AP-1转录因子的激活。当果蝇感觉神经元的轴突受损时，该核心通路介导再生，但相同细胞中外周感觉末梢的再生完全独立于该机制。在果蝇中，感觉末梢已被细胞生物学研究定义为树突，这表明DLK通路可能特异于轴突再生，而不用于树突再生。确定脊椎动物的感觉末梢是否使用保守的轴突再生途径或完全未探索的树突再生途径进行修复将是理解PN的关键基础。在这项探索性的工作中，将使用两条主要的实验路线来确定用于在皮肤中再生脊椎动物感觉末梢的修复途径。神经支配斑马鱼皮肤的感觉神经元将被用作所有这些实验的模型。斑马鱼幼虫感觉神经元被称为Rohon-Beard（RB）神经元，可以用目前的方法进行成像和操作，因此这些细胞将被用作研究感觉末梢细胞生物学和损伤反应的第一个模型。类似的方法，然后将开发背根神经节神经元（DRG），因为这些是最相关的了解PN。为了确定脊椎动物的游离感觉末梢是果蝇的树突，还是脊椎动物历史上分类的轴突，我们将确定它们微管的极性。所有已知的树突都含有至少50%的负端微管，而轴突接近100%的正端微管。微管极性从未在脊椎动物感觉末梢中进行过测定，因此这将在RB和DRG细胞中进行。为了确定是否损伤的感觉末梢触发确定的轴突再生途径或一种新的树突再生途径，我们将开发DLK信号的标记物，并比较反应的中央轴突损伤和外周感觉末梢损伤的斑马鱼感觉神经元。这两条实验路线将为理解感觉末梢如何修复以及这一过程如何在PN患者中失败奠定基础。