Trafficking and endosomal sorting of APP and BACE-1

APP 和 BACE-1 的运输和内体分选

• 批准号: 8753904
• 负责人: Subhojit Roy
• 金额: $ 31.78万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8753904
• 关键词: Alzheimer' s Disease; Amyloid; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Axon; Biogenesis; Biological; Biological Assay; Biological Models; Brain; Brain imaging; Cells; Cleaved cell; Collaborations; Coupling; Data; Dendrites; Deposition; Disease; Distal; Economics; Endocytosis; Endosomes; Epidemic; Event; Exocytosis; Fluorescence; Functional disorder; Generations; Goals; Golgi Apparatus; Health; Human; Image; In Situ; Laboratories; Lead; Life; Location; Marketing; Membrane; Microfluidic Microchips; Modeling; Molecular; Mus; Neuroglia; Neurons; Organelles; Pathway interactions; Patients; Peptide Fragments; Peptides; Pharmaceutical Preparations; Play; Presynaptic Terminals; Production; Proteins; Proteolysis; Recycling; Reporting; Research; Role; Route; Site; Sorting - Cell Movement; Synapses; Synaptic Vesicles; Testing; Therapeutic; Time; Toxic effect; Vesicle; Work; amyloid peptide; amyloid precursor protein processing; amyloidogenesis; beta-site APP cleaving enzyme 1; in vivo; induced pluripotent stem cell; insight; interest; novel; presynaptic; prevent; research study; secretase; social; tool; trafficking; transcytosis; two-photon

DESCRIPTION (provided by applicant): The amyloid precursor protein (APP) is sequentially cleaved by β- and -γsecretases to generate amyloid β-peptide (Aβ) in the brain - a central player in Alzheimer's disease. APP cleavage by β-secretase-1 (BACE-1) is the rate-limiting step for production of Aβ. Aβ is believed to exert its toxicity on neurons while in a soluble and oligomeric state, prior to deposition as insoluble fibrils in brain. Thus, for reasons related to both pathophysiology and therapeutics, understanding mechanisms and pathways of Aβ generation from APP is a major focus of many laboratories. An intriguing aspect of Aβ production is that its release is dependent upon neuronal activity - enhanced synaptic activity results in more Aβ release. Though pathways involved in trafficking and cleavage of APP in neurons are of obvious importance, the vast majority of previous studies on APP/BACE-1 trafficking have been carried out in non-neuronal cells. These findings may not always be applicable to neurons, which are highly polarized and are known to have very different trafficking mechanisms. Furthermore, inferences on how neuronal activity modulates APP processing by BACE-1 require work in neurons. The prevailing view is that at presynaptic terminals, heightened synaptic vesicle recycling that accompanies high synaptic activity results in increased internalization into endosomes of APP where proteolysis by secretases take place. However, our recent studies using live neuronal imaging showed rather surprising results in that APP and BACE-1 normally traffic in distinct vesicles - perhaps preventing unabated cleavage - but converge in dendrites upon activity-induction. This led us to propose a new model whereby neuronal activity brings together APP and BACE-1 in dendrites where the two molecules interact. Only subsequently are these two molecules sorted into axons to distal terminals. Experiments in this proposal will examine a number of predictions that emanate from this working model and dissect the trafficking pathways of APP and BACE-1; revealing their relationship to amyloidogenesis and neuronal activity. Four Aims are proposed: 1) Test the hypothesis that APP and BACE-1 are first conveyed into dendrites in distinct carriers after biogenesis. 2) Determine specific neuronal subcellular site(s) of APP/BACE-1 interaction and Aβ release. 3) Determine the biogenesis and molecular composition of the axonal APP/BACE-1-carrying organelle. 4) Visualize APP/BACE-1 associations in brains and in human induced pluripotent stem cells (iPSCs). Collectively, results from these studies will provide new insights into the trafficking pathways of APP and BACE-1 and demonstrate how neuronal activity modulates these pathways to enhance APP cleavage and Aβ release.

描述（由申请人提供）：淀粉样前体蛋白（APP）依次被β-和-γ分泌酶裂解，在大脑中产生淀粉样β-肽（Aβ）——β-分泌酶裂解APP的关键因素。 1 (BACE-1) 是 Aβ 产生的限速步骤，Aβ 被认为在沉积之前处于可溶和寡聚状态时对神经元发挥毒性。因此，出于与病理生理学和治疗学相关的原因，了解 APP 生成 Aβ 的机制和途径是许多实验室的主要关注点，Aβ 生成的一个有趣的方面是它的释放取决于神经活动。增强的突触活性导致更多的 Aβ 释放，尽管参与神经元中 APP 运输和裂解的途径显然很重要，但之前绝大多数关于 APP/BACE-1 运输的研究都是在这些发现可能并不总是适用于神经元，因为神经元是高度极化的，并且已知具有非常不同的运输机制。此外，关于神经活动如何调节 BACE-1 的 APP 处理的推断需要在神经元中进行研究。观点认为，在突触前末梢，伴随高突触活性的填充突触小泡回收导致 APP 内体的内化增加，在内体中发生分泌酶的蛋白水解。然而，我们最近使用活体神经元成像的研究显示出相当令人惊讶的结果，APP 和 BACE-1 通常在不同的囊泡中运输（可能会阻止不减弱的分裂），但在活动诱导时会聚在树突中，这使我们提出了一种新的神经元模型。活性将 APP 和 BACE-1 聚集在树突中，这两个分子在树突中相互作用。只有随后，这两个分子才会被分类到远端的轴突中。从该工作模型中得出的预测并剖析了 APP 和 BACE-1 的运输途径；揭示了它们与淀粉样蛋白生成和神经元活动的关系：1) 检验 APP 和 BACE-1 首先被输送到树突中的假设。 2）确定特定的神经元 APP/BACE-1 相互作用和 Aβ 释放的亚细胞位点 3) 确定轴突 APP/BACE-1 携带细胞器的生物发生和分子组成 4) 可视化大脑和人类中的 APP/BACE-1 关联。总的来说，这些研究的结果将为 APP 和 BACE-1 的运输途径提供新的见解，并证明神经活动如何调节这些细胞。增强 APP 裂解和 Aβ 释放的途径。