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.

项目摘要 学习、记忆和认知的正常运作需要依赖于活动的强化 兴奋性突触通过一种称为长时程增强(LTP)的过程在海马体中发生。LTP可以是 与淀粉样多肽-β(Aβ)孵育对体外培养的海马片的损伤；浓度增加 这种多肽与阿尔茨海默病(AD)早期突触缺陷高度相关，阿尔茨海默病(AD)是一种进行性 神经退行性疾病。已知LTP需要钙/钙调蛋白依赖的蛋白激酶II(CaMKII)， 具体地说，它定位于兴奋性突触，由CaMKII与NMDA型直接结合驱动 谷氨酸受体GluN2B。CaMKII对兴奋性突触的这种定位因与 Aβ，揭示了Aβ诱导的突触缺陷的潜在机制。有趣的是， 外源性Aβ孵育引起的LTP和CaMKII运动因淀粉样蛋白前体的丢失而减轻 蛋白质(APP)。虽然APP经历的蛋白水解性切割形成Aβ的特征很好，但这一明显 下游作为Aβ诱导的损伤的中介物的作用在很大程度上仍未被探索。重要的是，个人 唐氏综合征(DS)是一种遗传性发育障碍，由于三联反应，APP水平升高 应用程序的基因。由于内源性APP的缺失会使神经元对Aβ引起的突触缺陷“不敏感”，它 反过来，这些升高的APP水平可能是真的，使神经元对Aβ的影响“敏感”。初步结果 提示APP不仅在介导外源性Aβ所致的CaMKII损伤中是必需的，而且在调节CaMKII损伤中也是必需的。 足以破坏异种细胞中CaMKII-GluN2B的结合，进一步暗示APP是 A下游β诱导的CaMKII损伤。因此，该提案将调查APP角色的各个方面 作为Aβ的介质，包括高水平表达APP的神经元是否对Aβ诱导更敏感 突触损伤，APP蛋白的哪个结构域(S)是介导这些损伤所必需的，以及 APP和Aβ下游的哪种特定机制(S)驱动LTP相关CaMKII的损害 有动静。为了回答这些问题，我们将利用几个不同的遗传小鼠品系，包括一个 DS模型，APP的各种突变结构，以及最近开发的可光激活的CaMKII。结果是 将为APP在驱动突触中的作用提供有价值的见解 Aβ在AD和DS中引起的损害(潜在的海马体记忆缺陷)。