Characterization of amyloid-β:α7β2-nicotinic acetylcholine receptor interactions relevant to Alzheimer's disease

淀粉样蛋白-β 的表征：α7β2-烟碱乙酰胆碱受体相互作用与阿尔茨海默病相关

• 批准号: 10259669
• 负责人: Andrew Anthony George
• 金额: $ 1.02万
• 依托单位: ST. JOSEPH'S HOSPITAL AND MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-15 至 2021-11-04
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10259669
• 关键词: APP-PS1; Abate; Acetylcholine; Acute; Address; Agonist; Alzheimer' s Disease; Alzheimer' s disease pathology; Alzheimer' s disease patient; Amyloid beta-Protein; Attention; Brain; Cerebral cortex; Cessation of life; Cholinergic Agonists; Clinical Trials; Code; Cognitive; Data; Dementia; Development; Disease; Disease Progression; Drosophila acetylcholine receptor alpha-subunit; Electrophysiology (science); Event; Exposure to; Failure; Futility; Genetic; Goals; Hippocampus (Brain); Human; Impaired cognition; Intervention; Kinetics; Knockout Mice; Lead; Length; Ligands; Link; Mecamylamine; Medical; Memory; Memory Loss; Methodology; Molecular; Mus; Mutagenesis; Mutate; Mutation; N-terminal; Nerve Degeneration; Nervous System Physiology; Neurofibrillary Tangles; Neurons; Nicotinic Antagonists; Nicotinic Receptors; Pathologic; Pathologic Processes; Peptides; Pharmacology; Play; Process; Property; Protein Isoforms; Research Personnel; Role; Seminal; Senile Plaques; Signal Transduction; Site; Site-Directed Mutagenesis; Symptoms; Testing; Therapeutic Intervention; Time; Uncertainty; Work; basal forebrain cholinergic neurons; cholinergic; cholinergic neuron; cognitive function; cognitive performance; effective therapy; excitotoxicity; memory consolidation; methyllycaconitine; mouse model; nerve supply; neuron loss; novel; novel strategies; novel therapeutic intervention; positive allosteric modulator; preservation; prevent; receptor; receptor function; response; selective expression; skills; tool

Alzheimer's disease (AD) is a neurodegenerative condition characterized by relentlessly progressive cognitive decline. There is no cure or effective treatment, especially given futility in preserving cognitive function in AD patients using interventions to remove amyloid-β (Aβ) plaques previously considered to be pathological hallmarks of disease. However, attention has turned to potential etiopathogenic roles of soluble, oligomeric forms of Aβ (oAβ). Moreover, remaining relevant is the loss of basal forebrain cholinergic neurons (BFCN) that provide widespread innervation to other brain centers critical for normal cognitive performance. A long-term goal of our work related to AD is to identify seminal and early disease processes that lead to BFCN functional instability and degeneration and can be targeted early enough to slow or stop neuronal death and memory compromise. Our preliminary findings support and merge aspects of both the oAβ and cholinergic hypotheses of AD. They show that sustained exposure in murine organotypic culture to oAβ causes hyperexcitation and eventual death of BFCN. These effects are blocked by antagonists of nicotinic acetylcholine receptors containing α7 subunits (α7*-nAChR). They also are absent for BFCN from nAChR β2 subunit knock-out mice. nAChR α7 and β2 subunits are enriched in BFCN where they combine to form a unique α7β2-nAChR subtype distinct from homomeric receptors composed of α7 subunits alone (α7-nAChR). Furthermore, deficits in spatial reference memory in an AD mouse model is normalized if those mice also lack β2 subunits. Most critical to this exploratory R21 project is our finding that oAβ mimics acetylcholine (ACh) in the ability to activate α7- and α7β2-nAChR single channel function. oAβ, but not ACh, uniquely alters single channel kinetics only for α7β2-nAChR. These studies support the project's overarching hypothesis that oAβ action at α7β2-nAChR leads to observed instability and demise of BFCN and ultimate cognitive compromise. This developmental project's goals are to identify sites for oAβ:α7β2-nAChR interactions and ways to prevent them without perturbing natural activation of α7β2-nAChR by ACh. Specific Aim 1 is to test the hypothesis that the site for human oAβ stimulation of human α7β2-nAChR function is different than that for ACh action as an agonist. Specific Aim 2 is to test the hypothesis that fragments of Aβ can block effects of oAβ at α7β2-nAChR while leaving ACh agonist action intact. Our proven skills will be used in nAChR expression, site-directed mutagenesis, pharmacology, and single channel electrophysiology. Results will provide a molecular description of oAβ:α7β2-nAChR interactions that lead to BFCN demise and could explain the emergence of dementia. These events occur early enough in disease progression to allow for novel therapeutic interventions to prevent or abate neuronal loss and useful, timely treatment of AD.

阿尔茨海默病（AD）是一种以持续进行性认知功能下降为特征的神经退行性疾病。目前尚无治愈或有效的治疗方法，特别是考虑到使用干预措施去除淀粉样蛋白-β（Aβ）斑块（先前被认为是疾病的病理学标志）在AD患者中保留认知功能方面无效。然而，人们的注意力已转向可溶性寡聚体形式Aβ（oAβ）的潜在致病作用。此外，仍然相关的是基底前脑胆碱能神经元（BFCN）的损失，提供广泛的神经支配的其他大脑中心的正常认知性能的关键。我们与AD相关工作的长期目标是确定导致BFCN功能不稳定和变性的种子和早期疾病过程，并且可以足够早地靶向以减缓或阻止神经元死亡和记忆受损。我们的初步研究结果支持并合并了AD的oAβ和胆碱能假说。他们表明，在小鼠器官型培养物中持续暴露于oAβ可导致BFCN过度兴奋和最终死亡。这些作用可被含有α7亚基的烟碱乙酰胆碱受体（α7*-nAChR）拮抗剂阻断。对于nAChR β2亚基敲除小鼠的BFCN，也不存在它们。nAChR α7和β2亚基在BFCN中富集，在BFCN中它们联合收割机形成独特的α7β2-nAChR亚型，与仅由α7亚基组成的同源受体（α7-nAChR）不同。此外，如果AD小鼠模型也缺乏β2亚基，则这些小鼠模型中的空间参考记忆缺陷被标准化。对于这个探索性的R21项目最关键的是我们发现oAβ模拟乙酰胆碱（ACh）激活α7-和α7β2-nAChR单通道功能的能力。oAβ（而非ACh）仅改变α7β2-nAChR的单通道动力学。这些研究支持该项目的总体假设，即α7β2-nAChR的oAβ作用导致观察到的BFCN不稳定和死亡以及最终的认知损害。该开发项目的目标是确定oAβ：α7β2-nAChR相互作用的位点，以及在不干扰ACh对α7β2-nAChR的自然激活的情况下防止它们的方法。具体目的1是检验以下假设：人oAβ刺激人α7β2-nAChR功能的位点与ACh作为激动剂的作用位点不同。具体目的2是检验以下假设：Aβ片段可阻断oAβ对α7β2-nAChR的作用，同时保持ACh激动剂作用完整。我们成熟的技能将用于nAChR表达，定点诱变，药理学和单通道电生理学。结果将提供导致BFCN死亡的oAβ：α7β2-nAChR相互作用的分子描述，并可以解释痴呆的出现。这些事件在疾病进展中发生得足够早，以允许新的治疗干预来预防或减轻神经元损失和有用的、及时的AD治疗。