Environmental Metals, Excitotoxicity and ALS

环境金属、兴奋性毒性和 ALS

• 批准号: 9926537
• 负责人: William D Atchison
• 金额: $ 0.81万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-12 至 2020-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9926537
• 关键词: Address; Adult; Affect; Amino Acid Transporter; Amyotrophic Lateral Sclerosis; Antioxidants; Astrocytes; Cells; Cessation of life; Chimera organism; Chronic; Coculture Techniques; DNA Sequence Alteration; Development; Disease; Disease Progression; Divalent Cations; Dose; Environmental Exposure; Event; Excitatory Amino Acids; Exposure to; Functional disorder; Generations; Glutamate Transporter; Glutamates; Glutathione; Goals; Homeostasis; Human; Lesion; Measures; Mediating; Mercury; Metal exposure; Metals; Methylmercury Compounds; Mitochondria; Motor; Motor Neurons; Mus; Mutation; Nerve Degeneration; Neurodegenerative Disorders; Neuronal Injury; Neurons; Onset of illness; Oxidative Stress; Pathogenesis; Phenotype; Play; Population; Process; Production; Proteins; Reactive Oxygen Species; Regulation; Risk Factors; Role; Secondary to; Single Nucleotide Polymorphism; Slice; Spinal Cord; System; Testing; Text; Time; Toxic Environmental Substances; Toxic effect; Transgenic Mice; base; cell type; comparative; course development; design; early onset; environmental agent; excitotoxicity; experimental study; gene environment interaction; genetic linkage; mRNA Expression; methylmercury exposure; mitochondrial dysfunction; motor impairment; motor neuron development; motor neuron function; mouse model; mutant; overexpression; postnatal; postsynaptic; pre-clinical; progressive neurodegeneration; public health relevance; response; superoxide dismutase 1; synaptic function; uptake

 DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, is a progressive neurodegenerative disease resulting in motor nerve degeneration and death. Both familial (FALS) and sporadic (SALS) forms exist; the latter greatly predominate. Its cause is unknown. Overstimulation of glutamatergic function - excitotoxicity - with increased Ca2+ and generation of reactive oxygen species (ROS), plays an important, if not integral role, though other mechanisms likely contribute to ALS pathogenesis. Interaction of motor neurons (MNs) and astrocytes (ASTs) appear to contribute to disease development. Environmental contribution to ALS has been postulated often, but to date not systematically tested. We propose to examine the interaction of the environmental toxicant methylmercury (MeHg) with two genetic mutations found in humans with ALS. Chronic postnatal MeHg exposure of mice with a mutation in superoxide dismutase-1 (SOD1G93A, G93A) hastens the onset of ALS phenotype compared to untreated G93A mice or wt mice exposed to identical MeHg concentrations. We will now test the hypothesis that chronic, low dose, MeHg exposure beginning postnatally enhances development and progression of ALS phenotype in the G93A and G85R SOD1 mutants by increasing [Ca2+]i, generating ROS and inducing mitochondrial toxicity secondary to enhanced release of glutamate (Glu) or actions on AST Glu transporters (EAAT1-2). The two SOD1 mutant strains differ in their time course of development of ALS phenotype and in their primary toxic focus. The G93A mice develop phenotype in ~4 mos and disease is MN-directed. G85R mice develop ALS phenotype over 7-9 months and disease is AST-based. This design will allow us to compare the roles of ASTs and MNs to MeHg induced responses. Specific Aim 1: Examines the development of ALS phenotype and relative role of MNs and ASTs during chronic adult MeHg exposure. Specific Aim 2: Examines oxidative stress as a contributor to MeHg-induced enhancement of ALS phenotype. Specific Aim 3: Examines the cell autonomy of MN function in response to MeHg. Interactions between ASTs and MNs will be examined in chimeric cultures of wt and SOD-1 cells to assess their potential roles in the development of excitotoxicity in MeHg-induced enhancement of ALS phenotype. Early onset effects preceding development of ALS phenotype will be examined using spinal cord slices and co-cultures of MNs and ASTs, from the G93A and G85R strains. Glu-mediated excitatory postsynaptic currents and elevation of [Ca2+] i and levels of ROS will test for MeHg-induced excitotoxicity. Steady- state mRNA expression levels for EAAT1-2 and proteins involved in [Ca2+] i regulation will be measured during development of ALS phenotype to correlate with studies done in cells in culture. MNs in culture derived from SOD1 mice or wt will allow examination of early effects of MeHg on Glu function, [Ca2+] i oxidative stress or mitochondrial damage in isolation. Results of the proposed study should permit assessment of the role of MeHg-induced Glu- mediated excitotoxicity in facilitating development of MN dysfunction and provide verification for the postulate that environmental exposure to metals is a potential risk factor for susceptible populations in development of ALS.

 描述（由申请人提供）：肌萎缩侧索硬化症（ALS）或卢伽雷氏病是一种进行性神经退行性疾病，导致运动神经变性和死亡。家族性（FALS）和散发性（SALS）两种形式都存在；后者占主导地位。其原因尚不清楚。谷氨酸能功能的过度刺激——兴奋性毒性——伴随着 Ca2+ 的增加和活性氧 (ROS) 的产生，即使不是不可或缺的作用，也起着重要的作用，尽管其他机制可能有助于 ALS 发病机制。运动神经元 (MN) 和星形胶质细胞 (AST) 的相互作用似乎有助于疾病的发展。人们经常假设环境对 ALS 的影响，但迄今为止尚未进行系统测试。我们建议研究环境毒物甲基汞 (MeHg) 与 ALS 患者中发现的两种基因突变之间的相互作用。与未治疗的 G93A 小鼠或暴露于相同 MeHg 浓度的野生型小鼠相比，超氧化物歧化酶 1（SOD1G93A、G93A）突变的小鼠出生后长期接触 MeHg 会加速 ALS 表型的发作。我们现在将测试以下假设：出生后开始的慢性、低剂量甲基汞暴露通过增加 [Ca2+]i、产生 ROS 并诱导继发于谷氨酸 (Glu) 释放增加或 AST Glu 转运蛋白 (EAAT1-2) 作用的线粒体毒性，从而增强 G93A 和 G85R SOD1 突变体中 ALS 表型的发育和进展。两种 SOD1 突变株在 ALS 表型发展的时间过程和主要毒性焦点方面有所不同。 G93A 小鼠在约 4 个月内形成表型，并且疾病是 MN 导向的。 G85R 小鼠在 7-9 个月内出现 ALS 表型，并且疾病是基于 AST 的。这种设计将使我们能够比较 AST 和 MN 对 MeHg 诱导的反应的作用。具体目标 1：检查成人慢性甲基汞暴露期间 ALS 表型的发展以及 MN 和 AST 的相对作用。具体目标 2：研究氧化应激对甲基汞诱导的 ALS 表型增强的影响。具体目标 3：检查 MN 功能响应 MeHg 的细胞自主性。将在 wt 和 SOD-1 细胞的嵌合培养物中检查 AST 和 MN 之间的相互作用，以评估它们在 MeHg 诱导的 ALS 表型增强中兴奋性毒性发展中的潜在作用。将使用脊髓切片以及来自 G93A 和 G85R 菌株的 MN 和 AST 的共培养物来检查 ALS 表型发展之前的早期发病效应。 Glu 介导的兴奋性突触后电流以及 [Ca2+]i 和 ROS 水平的升高将测试 MeHg 诱导的兴奋性毒性。在 ALS 表型发育过程中，将测量 EAAT1-2 和参与 [Ca2+]i 调节的蛋白质的稳态 mRNA 表达水平，以便与培养细胞中进行的研究相关联。来自 SOD1 小鼠或野生型的培养物中的 MN 将允许单独检查 MeHg 对 Glu 功能、[Ca2+] i 氧化应激或线粒体损伤的早期影响。拟议研究的结果应能够评估 MeHg 诱导的 Glu 介导的兴奋性毒性在促进 MN 功能障碍发展中的作用，并为以下假设提供验证：金属环境暴露是易感人群发生 ALS 的潜在危险因素。

项目成果

Acute neurotoxicant exposure induces hyperexcitability in mouse lumbar spinal motor neurons.

急性神经毒物暴露会导致小鼠腰椎运动神经元过度兴奋。

• DOI: 10.1152/jn.00775.2019
• 发表时间: 2020
• 期刊: Journal of neurophysiology
• 影响因子: 2.5
• 作者: Sceniak,MichaelP;Spitsbergen,JakeB;Sabo,ShastaL;Yuan,Yukun;Atchison,WilliamD
• 通讯作者: Atchison,WilliamD

Effects of methylmercury on spinal cord afferents and efferents-A review.

• DOI: 10.1016/j.neuro.2016.12.007
• 发表时间: 2017-05
• 期刊: Neurotoxicology
• 影响因子: 3.4
• 作者: Colón-Rodríguez A;Hannon HE;Atchison WD
• 通讯作者: Atchison WD