Roles of Cholesterol and Membrane Nanodomains in the Amyloidogenic Pathway

胆固醇和膜纳米结构域在淀粉样蛋白生成途径中的作用

• 批准号: 9333750
• 负责人: Anne K Kenworthy
• 金额: $ 360.44万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-04-01 至 2022-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9333750
• 关键词: Abeta synthesis; Alzheimer' s Disease; American; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Binding; Biological; C-terminal; Cell membrane; Cells; Cholesterol; Cleaved cell; Clupeidae; Complex; Coupled; Development; Disease; Environment; Enzymes; Etiology; Future; G-substrate; Length; Lipids; Literature; Measurement; Membrane; Membrane Fluidity; Membrane Microdomains; Membrane Proteins; Modeling; Molecular; Molecular Conformation; Monitor; Neurons; Pathway interactions; Pharmacology; Phase; Plasma; Play; Production; Property; Protein Dynamics; Proteins; Research; Role; Structure; Testing; Therapeutic; Vesicle; Work; amyloid formation; base; beta secretase; biophysical analysis; experimental study; gamma secretase; insight; membrane model; polypeptide; preference; protein structure; segregation; three dimensional structure; tool

Project Summary Roles of Cholesterol and Membrane Nanodomains in the Amyloidogenic Pathway Cholesterol is thought to play a key regulatory role in the formation of the amyloid-β polypeptide (Aβ) via the amyloidogenic pathway in which the full length amyloid precursor protein is cleaved by β-secretase to release is transmembrane 99 residue C-terminal domain (C99). C99 is then cleaved by γ-secretase to release Aβ. Membrane cholesterol appears to promote the amyloidogenic pathway, with much evidence pointing to a mechanism involving cholesterol-enriched regions of the plasma membrane often referred to as lipid rafts. According to this model, cholesterol promotes partitioning both of APP and C99 into lipid rafts, which are enriched in β-secretase and γ-secretase, thereby activating amyloidogenic cleavage. Rafts are therefore proposed to spatially segregate the amyloidogenic pathway from the bulk membrane phase. However, much of the evidence in support of this model is indirect. It is the premise of this work that it is important to test this model which, if correct, suggests a strategy for reducing Aβ formation by reducing raft partitioning of APP/C99. On the other hand, if the model is incorrect, the existing literature supporting this model may need to be re- assessed and the pursuit of therapeutic strategies based on this model would possibly need to be viewed as a red herring. A sub-premise of this work is that it is critical to conduct studies of the biophysical and structural biological basis for partitioning of C99/APP between raft and non-raft phases. These studies will provide fundamental insight how major changes in membrane phase properties impact membrane protein structure and localization. Moreover, a molecular understanding of the basis for the phase partitioning preferences of APP and C99 may inspire rational pharmacological strategies for altering the phase preferences of these molecules for the purpose of reducing Aβ formation. We note that in order to maintain an appropriate (feasible!) scope for the studies to be carried out, we will focus on γ-secretase and C99. Studies of full length APP and β-secretase represent a future direction for this work after the completion of the aims below. Aim 1. Test the hypothesis that C99 and γ-secretase preferentially localize to membrane raft domains. Aim 2. Test the hypothesis that raft-association alters the structure of C99. Aim 3. Determine how the cleavage of C99 by γ-secretase is modulated by membrane partitioning, membrane fluidity, C99 structure, and C99-cholesterol complex formation.

胆固醇和膜纳米结构域在淀粉样蛋白生成途径中的作用 胆固醇被认为在淀粉样β多肽（Aβ）的形成中起关键的调节作用， 淀粉样蛋白生成途径，其中全长淀粉样蛋白前体蛋白被β-分泌酶切割以释放 是跨膜99个残基的C-末端结构域（C99）。然后C99被γ-分泌酶裂解以释放Aβ。 膜胆固醇似乎促进淀粉样蛋白生成途径，许多证据表明， 该机制涉及质膜的胆固醇富集区域，通常称为脂筏。 根据这个模型，胆固醇促进APP和C99分配到脂筏中，脂筏是 富含β-分泌酶和γ-分泌酶，从而激活淀粉样蛋白裂解。因此，木筏 提出从本体膜相空间分离淀粉样蛋白生成途径。然而，许多 支持这个模型的证据是间接的。检验这一点很重要，这是这项工作的前提 该模型（如果正确）表明通过减少APP/C99的筏分配来减少Aβ形成的策略。 另一方面，如果模型是不正确的，现有的文献支持这一模型可能需要重新， 评估和追求基于这种模式的治疗策略可能需要被视为一种 转移注意力这项工作的一个子前提是，进行生物物理和结构研究至关重要。 C99/APP在筏和非筏阶段之间分配的生物学基础。这些研究将提供 膜相性质的主要变化如何影响膜蛋白结构的基本见解 和本地化。此外，分子理解的基础上相分配的偏好， APP和C99可能会激发合理的药理学策略，以改变这些相的偏好， 目的是减少Aβ形成。我们注意到，为了保持适当的 （可行！）根据研究的范围，我们将重点关注γ-分泌酶和C99。全长研究 APP和β-分泌酶代表了完成以下目标后这项工作的未来方向。 目标1.检验C99和γ-分泌酶优先定位于膜筏结构域的假设。 目标二。验证筏状缔合改变C99结构的假设。 目标3.确定γ-分泌酶对C99的裂解如何通过膜分配调节， 膜流动性、C99结构和C99-胆固醇复合物形成。