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

• 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
• 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

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（由主要研究者提供）： 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，通过增加神经元GSH可减轻细胞死亡。星形胶质细胞保护神经元免受毒素相关的OS和随后的凋亡通过？谷氨酰循环，其维持神经元GSH稳态。对这种神经保护通路的理解，特别是其调控成分和物种比较，最终可能导致对破坏性神经退行性疾病的新型临床干预，并建立准确的模型系统。假设：我们假设，在星形胶质细胞-神经元轴内，存在一种高效的、受调节的通路，该通路由能够增强神经元GSH稳态以响应EtOH（E）和帕金森氏病产生的环境毒素的组分组成，从而最小化神经元的死亡。然而，这些环境交叉应激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：目的之一是利用神经元和星形胶质细胞的培养，单独和共培养，以解决鱼藤酮，百草枯和E对星形胶质细胞和神经元成分的直接影响？谷氨酰循环实验参数将是单独或组合的环境毒素对GSH的关键前体、GSH酶促合成和发生神经保护的该机制的组分的内向运输的影响。具体目标2：目标2将解决神经保护通路的三个基本组成部分的调节。有待确定的是对毒素的调节和破坏反应的基本机制。这些将是通过多药耐药蛋白（Mrp）和两种质膜外肽酶，？谷氨酰转肽酶（GGT）和氨肽酶N（ApN）。具体目标3：目标3将使用体内模型将体外发现扩展至完整动物。实验将利用双光子激发显微镜，以确定毒素的影响，特别是在皮质星形胶质细胞和神经元在活的大脑。这些将是毒素暴露过程中GGT和ApN表达、GSH含量和中毒相关事件的延时测定。他们将利用Mrp 1、Mrp 4或GGT缺陷的转基因小鼠。概述：该提案提出了一种新的系统，通过该系统，神经胶质细胞保护神经元免受三种环境毒素的毒性影响。这些化合物会导致神经元因氧化损伤而死亡，而称为星形胶质细胞的细胞通过维持神经元抗氧化剂来防止这种情况。我们将确定毒素是如何破坏它的（以防止这种情况发生），以及这个系统通常是如何控制的。