Trafficking and Endosomal Sorting of APP and BACE-1

APP 和 BACE-1 的运输和内体分选

• 批准号: 9268509
• 负责人: Subhojit Roy
• 金额: $ 31.37万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-11 至 2019-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9268509
• 关键词: Abeta synthesis; Alzheimer' s Disease; Amyloid; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Axon; Biogenesis; Biological Assay; Biological Response Modifier Therapy; Brain; Brain imaging; Cells; Cleaved cell; Collaborations; Complement; Coupling; Data; Dendrites; Deposition; Disease; Distal; Economics; Endocytosis; Endosomes; Epidemic; Event; Exocytosis; Fluorescence; Functional disorder; Generations; Goals; Golgi Apparatus; Human; Image; In Situ; Laboratories; Lead; Location; Membrane; Microfluidic Microchips; Modeling; Molecular; Mus; Neuroglia; Neurons; Organelles; Pathway interactions; Patients; Pharmaceutical Preparations; Play; Presynaptic Terminals; Production; Proteins; Proteolysis; Recycling; Reporting; Research; Role; Route; Site; Sorting - Cell Movement; Synapses; Synaptic Vesicles; System; Testing; Therapeutic; Time; Toxic effect; Vesicle; Work; abeta deposition; amyloid precursor protein processing; amyloidogenesis; beta secretase; beta-site APP cleaving enzyme 1; experimental study; gamma secretase; in vivo; induced pluripotent stem cell; insight; interest; novel; presynaptic; prevent; public health relevance; 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(由申请者提供)：淀粉样前体蛋白(APP)在大脑中被？和γ-分泌酶顺序切割，产生淀粉样多肽(A？)--阿尔茨海默病的中心角色。β-分泌酶-1(BACE-1)对APP的切割是生产A？的限速步骤。据信，在以不溶纤维的形式沉积在大脑中之前，Aü对处于可溶和低聚状态的神经元产生毒性。因此，由于与BTH病理生理学和治疗学相关的原因，了解APP产生Aü的机制和途径是许多实验室关注的主要问题。Aü产生的一个有趣的方面是，它的释放依赖于神经元活动--增强的突触活动导致更多的A？释放。尽管APP在神经元中转运和切割的途径很重要，但以往对APP/BACE-1转运的研究绝大多数都是在非神经细胞中进行的。这些发现可能并不总是适用于神经元，因为神经元是高度两极分化的，而且已知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。流行的观点认为，在突触前终末，伴随着高突触活性的突触小泡的高度循环导致APP内体的内化增加，在内体中发生分泌酶的蛋白分解。然而，我们最近使用实时神经元成像的研究显示，相当令人惊讶的结果是，APP和BACE-1通常在不同的小泡中流动--也许可以防止有增无减的分裂--但在活动诱导后聚集在树突中。这导致我们提出了一个新的模型，即神经元活动将APP和BACE-1在树突中结合在一起，这两个分子在树突中相互作用。只有随后，这两个分子才被分成轴突和远端终末。这项提案中的实验将检验由这一工作模型产生的一些预测，并剖析APP和BACE-1的运输途径；揭示它们与淀粉样蛋白发生和神经元活动的关系。提出了四个目标：1)验证APP和BACE-1在生物发生后首先通过不同载体进入树突的假设。2)确定特定神经元 APP/BACE-1相互作用的亚细胞位点(S)和A？释放。3)确定轴突APP/BACE-1携带细胞器的生物发生和分子组成。4)在大脑和人类诱导的多能干细胞(IPSCs)中可视化APP/BACE-1的关联。总而言之，这些研究的结果将为APP和BACE-1的运输途径提供新的见解，并展示神经元活动如何调节这些途径以促进APP的切割和A？释放。