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（由适用提供）：淀粉样蛋白前体蛋白（APP）被β-和-γ-分泌酶依次裂解，以在大脑中产生淀粉样蛋白β-肽（Aβ），这是阿尔茨海默氏病的核心参与者。通过β-分泌酶-1（BACE-1）的APP裂解是生产Aβ的速率限制步骤。据信Aβ在可溶性和低聚状态下将其毒性施加在神经元上，然后将其作为大脑中不溶性原纤维的沉积。由于与病理生理学和治疗有关的原因，了解APP的Aβ生成的机制和途径是许多实验室的主要重点。 Aβ产生的一个有趣的方面是，它的释放取决于神经元活性 - 增强的突触活动会导致更多的Aβ释放。尽管在神经元中涉及贩运和清洁应用程序的途径显而易见，但在非神经元细胞中进行了绝大多数先前关于APP/BACE-1运输的研究。这些发现可能并不总是适用于高度两极化且已知具有非常不同的运输机制的神经元。此外，关于神经元活动如何调节BACE-1的应用程序需要的推论需要在神经元中工作。当前的观点是，在突触前末端，涉及高突触活动的突触囊泡回收增强导致内在化增加了对APP的内体，在这种情况下，在这种情况下进行了分泌的蛋白水解。但是，我们最近使用活神经元成像的研究显示，该应用程序中的结果相当令人惊讶，而BACE -1通常会在不同的蔬菜中流动 - 可能会阻止裂解不减，但在活动诱导后会在树突中融合。这导致我们提出了一个新模型，在该模型中，神经元活性在两个分子相互作用的树突中将App和Bace-1汇总在一起。随后，这两个分子将轴突分类到不同的末端。该提案中的实验将检查许多从该工作模型中散发出来的预测，并剖析APP和BACE-1的贩运途径；揭示了它们与淀粉样生成和神经元活性的关系。提出了四个目的：1）检验以下假设：在生物发生后，在不同的载体中首先将APP和BACE-1传递到树突中。 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）确定轴突应用程序/BACE-1携带细胞器的生物发生和分子组成。 4）可视化大脑和人类诱导多能干细胞（IPSC）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，并证明神经元活动如何调节这些途径以增强APP裂解和Aβ释放。