Role of autophagy in survival and regeneration of adult sensory neurons

自噬在成体感觉神经元存活和再生中的作用

• 批准号: RGPIN-2014-05035
• 负责人: Mearow, Karen
• 金额: $ 2.55万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588170
• 关键词: Role; autophagy; survival; regeneration; adult

Understanding the mechanisms underlying the response of neurons of the mature nervous system to stress and injury is the focus of this proposal. We have been studying mechanisms associated with neuronal survival and axonal regeneration in the dorsal root ganglion (DRG) sensory neurons of adult rodents, with particular interest in the role of heat shock proteins as well as the extracellular environment in these processes. DRG neurons and their axons are the primary sensors of our external environment and as such can be exposed to mechanical, thermal, chemical and osmotic stimuli that can potentially be deleterious. Adult sensory neurons, unlike their embryonic or neonatal counterparts or unlike neurons of the CNS, are relatively resistant to a variety of environmental stressors (heat, high glucose, nutrient starvation), and it is of interest to determine if these cells possess different coping mechanisms in this regard. However, in some situations these stimuli can cause axon terminal damage progressing to axonal dieback and potentially neuronal loss. Autophagy is a regulated cellular process for the degradation and recycling of various cellular components. While autophagy in the nervous system has often been considered in the context of neurodegeneration and stress responses, it is becoming clear that healthy neurons also exhibit basal autophagy although the mechanisms regulating this are not fully understood. It has also been suggested that autophagy may be uniquely regulated in neurons compared to other cell types and may be adapted to the local physiology in the axons. In contrast to studies of autophagy in the CNS there are relatively few studies investigating the role of autophagy in peripheral sensory neurons. Autophagy has been linked to neuronal survival, but the influence differs in different neuronal types and experimental contexts. Although increased numbers of autophagosomes have been observed in damaged axons, the role of autophagy in regeneration following injury remains unclear. Understanding how these processes can influence cellular responses to injury and subsequent neurite regrowth is a fundamental question in the nervous system. Our objectives are to investigate the contribution of autophagy to the response of DRG neurons under basal conditions and following experimental interventions–nutrient deprivation and oxidative stress. Preliminary data support the feasibility of the proposed experiments. We will determine whether autophagy has a positive or negative influence on neuronal survival and axonal regeneration by using chemical modulators of autophagy (eg., rapamycin, 3-MA, chloroquine), by overexpression or RNAi to alter expression of proteins known to regulate the process (eg., beclin, mTOR, Ulk1, HMGB1). We will investigate both neuronal survival and axonal regeneration. Obviously if the neurons undergo autophagic or apoptotic cell death, there will be no axonal regeneration. However, axonal dieback in response to local damage is a problem in the mature nervous system, and understanding how to prevent axonal dystrophy and promote axonal recovery and elongation is key to promoting recovery of function.

理解成熟神经系统的神经元对压力和损伤的反应机制是这项建议的重点。 我们一直在研究与成年啮齿动物背根神经节（DRG）感觉神经元的神经元存活和轴突再生相关的机制，特别感兴趣的热休克蛋白的作用，以及在这些过程中的细胞外环境。 DRG神经元及其轴突是我们外部环境的主要传感器，因此可能暴露于可能有害的机械，热，化学和渗透刺激。 成人感觉神经元，不像他们的胚胎或新生儿的对应或不像中枢神经系统的神经元，是相对抵抗各种环境应激源（热，高糖，营养饥饿），它是感兴趣的，以确定这些细胞是否拥有不同的应对机制在这方面。 然而，在某些情况下，这些刺激可导致轴突终末损伤，发展为轴突枯死和潜在的神经元损失。 自噬是一种受调控的细胞过程，用于降解和回收各种细胞组分。 虽然神经系统中的自噬通常被认为是神经退行性变和应激反应的背景下，它是越来越清楚，健康的神经元也表现出基础自噬，虽然调节这一机制尚未完全理解。 也有人提出，与其他细胞类型相比，自噬可能在神经元中受到独特的调节，并且可能适应轴突中的局部生理学。 与CNS中自噬的研究相反，有相对较少的研究调查外周感觉神经元中自噬的作用。 自噬与神经元存活有关，但其影响在不同的神经元类型和实验环境中有所不同。 虽然在受损轴突中观察到自噬体数量增加，但自噬在损伤后再生中的作用仍不清楚。 了解这些过程如何影响细胞对损伤的反应和随后的神经突再生是神经系统中的一个基本问题。 我们的目标是调查的贡献，自噬反应的DRG神经元在基础条件下，并在实验干预营养剥夺和氧化应激。 初步数据支持拟议的实验的可行性。 我们将通过使用自噬的化学调节剂（例如，雷帕霉素，3-MA，氯喹），通过过表达或RNAi改变已知调节该过程的蛋白质的表达（例如，beclin、mTOR、Ulk 1、HMGB1）。 我们将研究神经元的存活和轴突再生。 显然，如果神经元经历自噬或凋亡性细胞死亡，将不会有轴突再生。 然而，在成熟的神经系统中，响应于局部损伤的轴突死亡是一个问题，并且了解如何防止轴突营养不良和促进轴突恢复和伸长是促进功能恢复的关键。