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: 10592641
• 负责人: Andrew Anthony George
• 金额: $ 16.49万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10592641
• 关键词: Characterization; amyloid; nicotinic; acetylcholine; receptor

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.

阿尔茨海默氏病（AD）是一种神经退行性疾病，其特征是无情进行性认知下降。没有治愈或有效的治疗方法，尤其是在使用干预措施中保留AD患者的认知功能的能量，以去除先前被认为是疾病患者标志的淀粉样蛋白β（Aβ）斑块。然而，注意力转向了Aβ（OAβ）固体，寡聚形式的潜在病毒作用。此外，剩余的相关是基本前脑胆碱能神经元（BFCN）的丧失，该神经元（BFCN）为正常认知性能至关重要的其他大脑中心提供宽度的神经支配。我们与AD相关的工作的一个长期目标是确定导致BFCN功能不稳定性和变性的第二和早期疾病过程，并且可以足够及早地靶向以减慢或停止神经元死亡和记忆妥协。我们的初步发现支持和合并AD的OAβ和胆碱能假设的各个方面。他们表明，在鼠有机培养中持续暴露于OAβ会导致BFCN过度刺激和最终死亡。这些作用被含有α7亚基（α7*-NACHR）的烟碱乙酰胆碱受体的拮抗剂所阻断。 NACHRβ2亚基敲除小鼠也没有BFCN。 NACHRα7和β2亚基在BFCN中富含，在那里它们结合起来形成独特的α7β2-NACHR亚型，与单独由α7亚基（α7-NACHR）组成的同源受体不同。此外，如果这些小鼠也缺乏β2亚基，则将AD小鼠模型中的空间参考存储器定义为标准范围。对于这个探索性R21项目，我们最重要的是我们发现OAβ模拟乙酰胆碱（ACH）在激活α7-和α7β2-NACHR单通道功能的能力方面。 OAβ，但不是ACH，仅针对α7β2-NACHR来改变单个通道动力学。这些研究支持该项目的总体假设，即OAβ在α7β2-NACHR上的作用导致观察到BFCN的不稳定和灭亡和最终的认知妥协。这个发展项目的目标是识别OAβ的位点：α7β2-NACHR相互作用以及防止它们的方法，而不会通过ACH扰动α7β2-NACHR的自然激活。具体目的1是测试人类OAβ刺激人α7β2-NACHR功能的位点的假设与作为激动剂的ACh作用的位点不同。具体目的2是检验以下假设：Aβ的片段可以阻止OAβ在α7β2-NACHR上的影响，同时使ACH激动剂的作用完整。我们久经考验的技能将用于NACHR表达，定向诱变，药理学和单个通道电生理学。结果将提供OAβ的分子描述：α7β2-NACHR相互作用，导致BFCN灭亡，并可以解释痴呆症的出现。这些事件在疾病进展中足够早，以允许进行新的治疗干预措施，以预防或减轻神经元丧失和有用的AD治疗。

项目成果

A potential cost of evolving epibatidine resistance in poison frogs.

• DOI: 10.1186/s12915-023-01637-8
• 发表时间: 2023-06-28
• 期刊: BMC BIOLOGY
• 影响因子: 5.4
• 作者: York, Julia M.;Borghese, Cecilia M.;George, Andrew A.;Cannatella, David C.;Zakon, Harold H.
• 通讯作者: Zakon, Harold H.