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）被ß-和γ-分泌酶依次切割，在大脑中产生淀粉样蛋白ß-肽（ß），这是阿尔茨海默病的核心因素。ß-分泌酶-1 （BACE-1）裂解APP是ß生成的限速步骤。在以不溶性原纤维沉积在脑内之前，asas被认为在可溶性和低聚状态下对神经元施加毒性。因此，由于病理生理学和治疗学的原因，了解APP产生asb的机制和途径是许多实验室的主要关注点。asb产生的一个有趣的方面是它的释放依赖于神经元的活动——增强的突触活动导致更多的asb释放。虽然APP在神经元内的转运和切割通路具有明显的重要性，但以往绝大多数关于APP/BACE-1转运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，它们是高度极化的，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加工的推断需要在神经元中进行工作。普遍的观点是，在突触前末端，突触囊泡循环的增加伴随着高突触活性，导致APP内体的内化增加，分泌酶在APP内体进行蛋白质水解。然而，我们最近使用活神经元成像的研究显示了相当令人惊讶的结果，APP和BACE-1通常在不同的囊泡中运输-可能阻止未减弱的切割-但在活动诱导时在树突中聚集。这使我们提出了一种新的模型，即神经元活动将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被分类成轴突到远端。本提案中的实验将检查从该工作模型中产生的一些预测，并剖析APP和BACE-1的贩运途径；揭示它们与淀粉样蛋白形成和神经元活动的关系。我们提出了四个目的：1)验证APP和BACE-1在生物发生后首先通过不同的载体进入树突的假设。2)确定特定神经元