Mechanisms underlying glutamate dyshomeostasis in Alzheimer's disease

阿尔茨海默病谷氨酸稳态失调的机制

• 批准号: 10303751
• 负责人: PAUL ALLEN ROSENBERG
• 金额: $ 17.7万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2024-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10303751
• 关键词: Address; Aducanumab; Affect; Aging; Alzheimer' s Disease; Amyloid beta-Protein; Astrocytes; Biochemical; Biological Assay; Brain; Cell membrane; Clinical; Cytotoxin; Data; Defect; Dendritic Spines; Disadvantaged; Disease; Elements; Foundations; Functional disorder; GLAST Protein; Gene Expression Profile; Glutamate Transporter; Glutamates; Goals; Homeostasis; Homologous Gene; Human; Hyperactivity; Impaired cognition; Impairment; Intervention; Knock-out; Knockout Mice; Knowledge; Lead; Light; Long-Term Depression; Long-Term Potentiation; Mediating; Mitochondria; Modeling; Molecular; Monoclonal Antibodies; Neurons; Pathogenesis; Patients; Peptides; Play; Preparation; Presynaptic Terminals; Process; Production; Prosencephalon; Proteins; Publishing; Reporting; Rodent; Role; Slice; Synapses; Synaptosomes; Vesicle; Work; abeta oligomer; base; cell type; conditional knockout; experimental study; extracellular; insight; mitochondrial metabolism; mouse model; neuropathology; novel strategies; oAβ; prevent; proteoliposomes; reuptake; uptake

The critical neuropathology underlying the cognitive decline in Alzheimer's disease is the loss of synapses. A leading view of the pathogenesis of Alzheimer's disease is that synaptic abnormalities are produced that lead to enhanced synapse elimination. The synaptopathy in AD is thought to be due largely to the production of toxic soluble oligomers of the Aβ1-42 peptide (oAβ). Soluble Aβ oligomers, but not monomers, have been shown to cause synaptic dysfunction, manifest by inhibition of LTP, enhancement of LTD, loss of dendritic spines, biochemical abnormalities, and hyperactivity. The enhanced LTD and hyperactivity appear to be due to elevation of extracellular glutamate as a consequence of impaired glutamate reuptake. Although substantial evidence has accumulated to support this hypothesis, there are significant gaps in our understanding of how oAβ perturbs glutamate homeostasis. Specifically, the identity of the glutamate transporter or transporters targeted by oAβ to produce the defect in glutamate homeostasis is unknown, as are the molecular mechanisms by which glutamate transport function is compromised by oAβ. These gaps loom greater in light of recent evidence that monoclonal antibodies (aducanumab; BAN2401) targeting soluble Aβ oligomers in AD patients may slow cognitive decline. The major glutamate transporter in the forebrain is GLT- 1 (human homolog EAAT2), which represents 1% of brain protein. GLT-1 is expressed in both astrocytes and glutamatergic axon terminals. Recent work by the applicant using a conditional GLT-1 knockout (KO) has shown that GLT-1 expressed in axon terminals is the dominant transporter mediating glutamate uptake into crude synaptosome preparations, also known as plasma membrane vesicles (PMVs). GLT-1 expressed in presynaptic terminals has also been shown to play an important role in synaptic mitochondrial metabolism. Several studies suggest that in the human and in mouse models deficits in glutamate transporter expression and/or function occur in AD. In critical experiments, glutamate uptake into PMVs derived from brain slices was decreased when the slices were treated with oAβ, implicating neuronal GLT-1. The central hypothesis motivating this project is that GLT-1 is the primary mechanistic target of oAβ causing glutamate dyshomeostasis. Given these findings it is important to ascertain whether GLT-1 is the specific glutamate transporter targeted by oAβ, whether oAβ affects GLT-1 function in astrocytes or neurons, or both, and the molecular basis for the interaction of oAβ with GLT-1. The specific goals of this project are to: Aim 1: Identify the glutamate transporter whose function is impaired by oAβ. Aim 2: Determine the cellular localization of effects of oAβ on GLT-1 using a conditional GLT-1 KO. The pursuit of these goals will lead to a molecular understanding of how oAβ, the salient AD cytotoxins, perturb glutamate homeostasis in AD and ultimately lead to novel approaches to prevent and treat AD.

阿尔茨海默病认知能力下降的关键神经病理学基础是神经元的丢失。 突触阿尔茨海默病发病机制的主要观点是，突触异常是阿尔茨海默病的发病机制。 导致突触消除增强。AD中的突触病被认为主要是由于 Aβ1-42肽（oAβ）的有毒可溶性寡聚体的产生。可溶性Aβ寡聚体，但不是单体， 已显示引起突触功能障碍，表现为LTP抑制、LTD增强、 树突棘生化异常和多动症增强的LTD和多动症似乎 可能是由于谷氨酸再摄取受损导致细胞外谷氨酸升高。虽然 虽然已经积累了大量的证据来支持这一假设，但我们的研究仍存在重大差距。 了解oAβ如何扰乱谷氨酸体内平衡。具体来说，谷氨酸的身份 由oAβ靶向的一种或多种转运蛋白在谷氨酸体内平衡中产生缺陷是未知的， 谷氨酸转运功能受oAβ影响的分子机制。这些缺口隐约可见 鉴于最近有证据表明靶向可溶性Aβ的单克隆抗体（aducanumab; BAN 2401） AD患者中的低聚物可能会减缓认知能力下降。前脑中主要的谷氨酸转运体是GLT- 1（人类同源物EAAT 2），占大脑蛋白质的1%。GLT-1在星形胶质细胞和胶质细胞中表达， 神经元轴突终末。申请人最近使用条件性GLT-1敲除（KO）的工作已经 表明轴突终末表达的GLT-1是介导谷氨酸摄取的主要转运蛋白 转化为粗突触体制备物，也称为质膜囊泡（PMVs）。GLT-1 在突触前末梢中表达也被证明在突触线粒体中起重要作用。 新陈代谢.一些研究表明，在人类和小鼠模型中，谷氨酸转运蛋白的缺陷 表达和/或功能发生在AD中。在临界实验中，PMV对谷氨酸的摄取来源于 脑切片用oAβ处理后，脑切片减少，涉及神经元GLT-1。中央 激发该项目的假设是GLT-1是oAβ引起谷氨酸的主要机制靶点 稳态失调鉴于这些发现，重要的是要确定GLT-1是否是特定的谷氨酸 oAβ靶向的转运蛋白，无论oAβ是否影响星形胶质细胞或神经元中的GLT-1功能，或两者，以及 oAβ与GLT-1相互作用的分子基础。该项目的具体目标是： 目的1：鉴定oAβ损伤的谷氨酸转运体。 目的2：使用条件性GLT-1 KO确定oAβ对GLT-1作用的细胞定位。 对这些目标的追求将导致对oAβ，即突出的AD细胞毒素， 扰乱AD中的谷氨酸体内平衡，并最终导致预防和治疗AD的新方法。