APP as a mediator of amyloid beta effects on CaMKII synaptic functions

APP 作为 β 淀粉样蛋白对 CaMKII 突触功能影响的调节剂

• 批准号: 10750350
• 负责人: Matthew E Larsen
• 金额: $ 3.72万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-03 至 2026-08-02
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10750350
• 关键词: APLP1 gene; Abeta synthesis; Affinity; Alzheimer' s Disease; Alzheimer' s disease pathology; Alzheimer' s disease risk; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Automobile Driving; Binding; Cells; Chemicals; Chromosome 21; Cognition; Defect; Dementia; Dose; Down Syndrome; Elements; Excitatory Synapse; Future; Gene Proteins; Genetic; Glutamate Receptor; Hippocampus; Impairment; Incubated; Individual; Knock-out; Knockout Mice; Learning; Light; Long-Term Potentiation; Mediating; Mediation; Mediator; Membrane Proteins; Memory; Memory impairment; Modeling; Movement; Mus; N-Methylaspartate; Nature; Neurodegenerative Disorders; Neurons; Outcome; Peptides; Play; Population; Process; Protein Precursors; Proteins; Role; Signal Transduction; Slice; Stimulus; Synapses; Synaptic plasticity; Tertiary Protein Structure; Testing; Trisomy; abeta oligomer; age related; calmodulin-dependent protein kinase II; desensitization; developmental disease; developmental genetics; experimental study; extracellular; impaired driving performance; insight; knock-down; mutant; overexpression; prevent; protein expression; response; synaptic function; trafficking

Project Summary The proper functioning of learning, memory, and cognition requires the activity-dependent strengthening of excitatory synapses in the hippocampus via a process known as long-term potentiation (LTP). LTP can be impaired in ex vivo hippocampal slices by incubation with the peptide amyloid-β (Aβ); increased concentrations of this peptide are highly associated with early synaptic deficits in Alzheimer’s disease (AD), a progressive neurodegenerative disease. LTP is known to require the Ca2+/calmodulin-dependent protein kinase II (CaMKII), and specifically its localization to excitatory synapses, driven by direct binding of CaMKII to the NMDA-type glutamate receptor GluN2B. This localization of CaMKII to excitatory synapses is impaired by incubation with Aβ, revealing a potential mechanism underlying Aβ-induced synaptic deficits. Interestingly, the impairments of LTP and CaMKII movement caused by exogenous Aβ incubation are alleviated by loss of the amyloid precursor protein (APP). While the proteolytic cleavage that APP undergoes to form Aβ is well-characterized, this apparent downstream role as a mediator of Aβ-induced impairment remains largely unexplored. Importantly, individuals with Down syndrome (DS), a genetic developmental disorder, express increased levels of APP due to triplication of the APP gene. As loss of endogenous APP “desensitizes” neurons to the synaptic deficits caused by Aβ, it may conversely be true that these increased APP levels “sensitize” neurons to the effects of Aβ. Initial results indicate that APP is not only necessary to mediate CaMKII impairments caused by exogenous Aβ, but also sufficient to impair CaMKII-GluN2B binding in heterologous cells, further implicating APP as a direct mediator of downstream Aβ-induced CaMKII impairments. Thus, this proposal will investigate various aspects of APP’s role as a mediator of Aβ, including whether neurons expressing higher levels of APP are more sensitive to Aβ-induced synaptic impairments, which domain(s) of the APP protein are necessary to mediate these impairments, and which specific mechanism(s) downstream of APP and Aβ are driving impairments in LTP-related CaMKII movement. To answer these questions, we will be utilizing several different genetic mouse lines, including a model of DS, various mutant constructs of APP, and a recently developed photoactivatable CaMKII. The results of the experiments outlined in this proposal will provide valuable insight into the role of APP in driving synaptic impairment (underlying hippocampal memory deficits) caused by Aβ in both AD and DS.

项目概要 学习、记忆和认知的正常运作需要依赖于活动的强化 海马体中的兴奋性突触可以通过称为长时程增强（LTP）的过程来调节。 通过与肽淀粉样蛋白-β (Aβ) 一起孵育，使离体海马切片受损； 这种肽的含量与阿尔茨海默病 (AD) 的早期突触缺陷高度相关，阿尔茨海默病是一种进行性的疾病 已知神经退行性疾病需要 Ca2+/钙调蛋白依赖性蛋白激酶 II (CaMKII)， 特别是其对兴奋性突触的定位，由 CaMKII 与 NMDA 型的直接结合驱动 谷氨酸受体 GluN2B 与 CaMKII 的兴奋性突触定位会因与 GluN2B 一起孵育而受损。 Aβ，揭示了 Aβ 诱导的突触缺陷的潜在机制。 外源 Aβ 孵育引起的 LTP 和 CaMKII 运动因淀粉样蛋白前体的损失而减轻 虽然 APP 形成 Aβ 的蛋白水解裂解已被充分表征，但这种明显的现象 重要的是，个体作为 Aβ 诱导损伤中介者的下游作用在很大程度上仍未被探索。 患有唐氏综合症 (DS)（一种遗传发育障碍）的患者由于三倍体而表达 APP 水平升高 由于内源性 APP 的缺失，神经元对 Aβ 引起的突触缺陷“不敏感”。 相反，这些增加的 APP 水平可能使神经元对 Aβ 的影响“敏感”。 表明 APP 不仅是介导外源 Aβ 引起的 CaMKII 损伤所必需的，而且还 足以损害异源细胞中的 CaMKII-GluN2B 结合，进一步暗示 APP 作为 CaMKII-GluN2B 的直接介体 因此，本提案将研究 APP 作用的各个方面。 作为 Aβ 的介质，包括表达较高水平 APP 的神经元是否对 Aβ 诱导的更敏感 突触损伤，APP 蛋白的哪些结构域对于介导这些损伤是必需的，以及 APP 和 Aβ 下游的哪些特定机制正在驱动 LTP 相关 CaMKII 的损伤 为了回答这些问题，我们将利用几种不同的基因小鼠品系，包括 DS 模型、APP 的各种突变结构以及最近开发的可光激活 CaMKII。 本提案中概述的实验将为了解 APP 在驱动突触中的作用提供有价值的见解 AD 和 DS 中 Aβ 引起的损伤（潜在的海马记忆缺陷）。