Trafficking and endosomal sorting of APP and BACE-1

APP 和 BACE-1 的运输和内体分选

• 批准号: 8912971
• 负责人: Subhojit Roy
• 金额: $ 30.82万
• 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/8912971
• 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 ß- and γ-secretases to generate amyloid ß-peptide (Aß) in the brain - a central player in Alzheimer's disease. APP cleavage by ß-secretase-1 (BACE-1) is the rate-limiting step for production of Aß. Aß 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 bth pathophysiology and therapeutics, understanding mechanisms and pathways of Aß generation from APP is a major focus of many laboratories. An intriguing aspect of Aß production is that its release is dependent upon neuronal activity - enhanced synaptic activity results in more Aß 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 Aß 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 Aß release.

描述（由申请人提供）：淀粉样蛋白前体蛋白 (APP) 依次被 β- 和 γ- 分泌酶裂解，在大脑中生成淀粉样蛋白 β-肽 (Aß) - 阿尔茨海默病的核心参与者。 β-分泌酶-1 (BACE-1) 进行的 APP 裂解是 Aß 生成的限速步骤。 Aß被认为在以不溶性原纤维沉积在大脑中之前，在可溶性和寡聚状态下对神经元发挥毒性。因此，出于与病理生理学和治疗学相关的原因，了解 APP 生成 Aß 的机制和途径是许多实验室的主要焦点。 Aß 产生的一个有趣的方面是它的释放取决于神经元活动 - 增强的突触活动会导致更多的 Aß 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 运输的研究都是在非神经元细胞中进行的。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，关于神经元活动如何通过 BACE-1 调节 APP 处理的推断需要在神经元中进行研究。普遍的观点是，在突触前末梢，伴随高突触活性的突触小泡回收增强导致 APP 内体的内化增加，在 APP 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——可能会阻止有增无减的分裂——但在活动诱导时会聚在树突中。这促使我们提出了一种新模型，通过神经元活动将 APP 和 BACE-1 聚集在树突中，这两个分子相互作用。仅随后这两个分子才被分类成轴突至远端。该提案中的实验将检查该工作模型产生的许多预测，并剖析 APP 和 BACE-1 的贩运途径；揭示它们与淀粉样蛋白生成和神经元活动的关系。提出了四个目标： 1) 检验 APP 和 BACE-1 在生物发生后首先被转移到不同载体中的树突中的假设。 2）确定特定的神经元 APP/BACE-1 相互作用和 Aß 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 Aß 释放。