Astrocyte Control of Toxin-Mediated Neuron Death: Role of the Gamma-Glutamyl Path

星形胶质细胞控制毒素介导的神经元死亡：γ-谷氨酰路径的作用

基本信息

批准号：
7494548
负责人：
GEORGE I HENDERSON
金额：
$ 29.33万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-09-10 至 2009-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7494548
关键词：
Address Animals Antioxidants Apoptosis Apoptotic Area Astrocytes Biological Models Brain Cell Culture System Cell Death Cell membrane Cells Cerebral cortex Cessation of life Clinical Coculture Techniques Commit Cysteine Cystine Elements Ethanol Event Exopeptidase Exposure to Gamma-glutamyl transferase Glutamates Glutathione Glycine Homeostasis Human Image In Vitro Intervention Lead Life Mediating Microscopy Neurodegenerative Disorders Neuroglia Neurons Neurotoxins Organic Anion Transporters Oxidative Stress P-Glycoproteins Paraquat Parkinson Disease Pathway interactions Pattern Principal Investigator Process Proteins Regulation Regulatory Pathway Rodent Model Role Rotenone Source System Testing Therapeutic Intervention Time Toxic Environmental Substances Toxic effect Toxicology Toxin Transgenic Mice alanine aminopeptidase alcohol response cell injury cysteinylglycine gamma glutamyl path in vivo Model multi-photon neuron component neuroprotection neurotoxic nonhuman primate novel prevent protein expression research study response stressor toxin mediated neuron death two-photon

项目摘要

DESCRIPTION (provided by principal investigator): Background Toxin-mediated oxidative stress (OS) is a trigger that ultimately commits neurons to apoptotic death. The event can be associated with decreased cell glutathione (GSH) and cell death is mitigated by augmenting neuron GSH. Astrocytes protect neurons from toxin-related OS and subsequent apoptosis via the ?-glutamyl cycle, which maintains neuron GSH homeostasis. An understanding of this neuroprotective pathway, especially its regulatory components and species comparisons, could ultimately lead to novel clinical interventions for devastating neurodegenerative disorders as well as establish accurate model systems. Hypothesis: We hypothesize that within the astrocyte-neuron axis, there is a highly effective, regulated pathway consisting of components which can enhance neuron GSH homeostasis in response to EtOH (E) and Parkinson's Disease-producing environmental toxins, thereby minimizing death of neurons. However, there are exposure patterns to these environmental cross-stressors which damage components of the pathways, thereby impairing its neuroprotective capacity. Specific Aim 1: Aim one will utilize cultures of neurons and astrocytes, alone and in co-culture, to address the direct impact of rotenone, paraquat, and E on astrocyte and neuron components of the ?-glutamyl cycle. Experimental parameters will be effects of the environmental toxins, alone or in combination, on inward transport of key precursors of GSH, GSH enzymatic synthesis, and components of this machinery at which neuroprotection occurs. Specific Aim 2: Aim two will address regulation of three essential components of the neuroprotective pathway. To be determined will be basic mechanisms underlying regulatory and damaging responses to the toxins. These will be regulation of GSH efflux via multidrug resistance protein(s) (Mrp), and two plasma membrane ectopeptidases, ?-glutamyl transpeptidase (GGT) and aminopeptidase N (ApN). Specific Aim 3: Aim 3 will use an in vivo model to extend the in vitro findings to the intact animal. Experiments will utilize two-photon excitation microscopy to determine toxin effects specifically in cortical astrocytes and neurons in the living brain. These will be time-lapse determinations of expressions of GGT and ApN, GSH content and apoptosis-related events during toxin exposure. They will utilize transgenic mice deficient in Mrpl, Mrp4, or GGT. General Description: The proposal addresses a new system by which glial cells protect neurons from the toxic effects of three environmental toxins. These compounds can cause neurons to die as a result of oxidative damage and cells called astrocytes prevent this by maintaining neuron antioxidants. We will determine how the toxins damage it (to prevent this from happening), and how this system is normally controlled.

描述（由首席研究员提供）：背景毒素介导的氧化应激（OS）是最终导致神经元凋亡的触发因素。该事件可能与细胞谷胱甘肽 (GSH) 减少有关，并且通过增加神经元 GSH 可以减轻细胞死亡。星形胶质细胞通过β-谷氨酰循环保护神经元免受毒素相关的 OS 和随后的细胞凋亡的影响，从而维持神经元 GSH 稳态。了解这种神经保护途径，特别是其调节成分和物种比较，最终可能会导致针对破坏性神经退行性疾病的新型临床干预措施，并建立准确的模型系统。假设：我们假设星形胶质细胞-神经元轴内存在一条高效、受调节的通路，其组成部分可以增强神经元 GSH 稳态，以响应 EtOH (E) 和帕金森氏病产生的环境毒素，从而最大限度地减少神经元死亡。然而，这些环境交叉压力源的暴露模式会损害通路的组成部分，从而损害其神经保护能力。具体目标 1：目标一将利用单独和共培养的神经元和星形胶质细胞培养物，以解决鱼藤酮、百草枯和 E 对 α-谷氨酰循环的星形胶质细胞和神经元成分的直接影响。实验参数将是环境毒素单独或组合对谷胱甘肽关键前体的向内运输、谷胱甘肽酶促合成以及发生神经保护的该机制的组件的影响。具体目标 2：目标二将解决神经保护途径三个基本组成部分的调节。有待确定的是对毒素的监管和破坏性反应的基本机制。这些将通过多药耐药蛋白（Mrp）和两种质膜外肽酶，γ-谷氨酰转肽酶（GGT）和氨肽酶N（ApN）来调节GSH流出。具体目标 3：目标 3 将使用体内模型将体外研究结果扩展到完整的动物。实验将利用双光子激发显微镜来确定毒素对活体大脑皮质星形胶质细胞和神经元的影响。这些将是毒素暴露期间 GGT 和 ApN 表达、GSH 含量以及细胞凋亡相关事件的延时测定。他们将利用缺乏 Mrpl、Mrp4 或 GGT 的转基因小鼠。概述：该提案提出了一种新系统，神经胶质细胞通过该系统保护神经元免受三种环境毒素的毒性作用。这些化合物会导致神经元因氧化损伤而死亡，而星形胶质细胞通过维持神经元抗氧化剂来防止这种情况发生。我们将确定毒素如何损害它（以防止这种情况发生），以及如何正常控制该系统。