Trimming of Amyloid Peptides by Gamma-Secretase

γ-分泌酶修饰淀粉样肽

• 批准号: 8426771
• 负责人: Michael S Wolfe
• 金额: $ 8.8万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8426771
• 关键词: Active Sites; Address; Alzheimer' s Disease; Alzheimer' s disease risk; Amides; Amino Acids; Amyloid Proteins; Amyloid beta-Protein Precursor; Aspartate; Aspartic Endopeptidases; Biochemical; C-terminal; Carboxypeptidase; Charge; Cleaved cell; Complex; Disease; Enzymes; Event; Goals; Head; Lead; Length; Lipids; Measurement; Membrane; Methods; Mind; Minor; Modeling; Multienzyme Complexes; Mutation; Pathogenesis; Peptide Hydrolases; Peptides; Process; Property; Proteolysis; Recombinants; Relative (related person); Side; Site; Testing; Time; Transmembrane Domain; Work; amyloid peptide; carboxylate; extracellular; gamma secretase; mutant; neurotoxic; peptide A; presenilin; recombinant peptide; research study; secretase; self assembly

DESCRIPTION (provided by applicant): The amyloid -protein (A¿), strongly implicated in the pathogenesis of Alzheimer's disease (AD), is formed by the sequential cleavage of the amyloid -protein precursor (APP) by ¿- and ?-secretases. ?-Secretases cleaves the APP transmembrane domain at the ? site, producing the C-terminus of A¿, and at the ? site, producing the N-terminus of the APP intracellular domain. The goal of this project is to understand the process by which the ?--secretase complex trims long A¿ peptide intermediates into shorter forms and how disease- causing PS mutations alter activity. With these goals in mind, the following specific questions will be addressed: (1) Which shorter A¿ peptides are produced via the trimming of specific long A¿ peptides? We will identify and quantify all A¿ peptides formed from normal ? cleavage products A¿49 and A¿48. We will also determine if A¿50, which is not a ? normal cleavage product, leads to the formation of the otherwise unobserved A¿47, A¿44 and A¿41. The result will help answer the question of whether trimming by every 3 residues is a general rule, and if so, how rigid is this rule. (2) How does ?-secretase accomplish C-terminal tripeptide trimming of long A¿ peptide intermediates? Evidence supports initial ? proteolysis to produce long A¿ peptides and then cleavage every 3 residues, but the mechanism by which this occurs is unknown. We hypothesize that the newly formed carboxy-terminus of long A¿ produced upon ? cleavage by ?-secretase is critical for trimming and with apparent precision by every 3 residues. To test this hypothesis, we will examine the ability of C-terminal amides of long A¿ peptides to serve as substrates. (3) What are the effects of Alzheimer-causing PS1 mutations on the trimming of long A¿ peptides? We have shown that such PS1-mutant ?-secretases complexes can increase the proportion of long-to-short A¿ peptides from recombinant APP substrate. Here, we will test the conversion of A¿49 and A¿48 by these mutant protease complexes, examining the A¿ products that are formed, the proportion of these products, and their rates of formation relative to the wild-type complex. We hypothesize that the disease-causing PS1 mutations increase the proportion of long A¿ peptides by slowing down the trimming process in general. PUBLIC HEALTH RELEVANCE: The goal of this project is to understand ?-secretase, a complex enzyme critical to the cause of Alzheimer's disease. Biochemical experiments are proposed to test hypotheses about how this enzyme works and how it is dysregulated in Alzheimer's disease.

描述（由申请人提供）：淀粉样蛋白（A¿）与阿尔茨海默氏病（AD）的发病机制密切相关，它是由淀粉样蛋白前体（APP）连续裂解而形成的。 - 和 ?- 分泌酶在 ? 位点切割 APP 跨膜结构域，产生 A¿ ，并在 ? 位点，产生 APP 胞内结构域的 N 末端。该项目的目标是 ?-分泌酶复合物修剪长 A¿考虑到这些目标，将解决以下具体问题：（1）哪个更短的A¿肽是通过修剪特定的长 A¿我们将识别并量化所有 A¿由正常裂解产物 A 形成的肽？ 49 和 A¿ 48. 我们还将确定 A¿ 50，这不是 ? 正常裂解产物，导致形成其他未观察到的 A¿ 47、A?? 44 和 A¿ 41. 结果将有助于回答每 3 个残基修剪是否是一般规则的问题，如果是，该规则的严格程度如何（2）？-分泌酶如何完成长 A 的 C 端三肽修剪。肽中间体？证据支持初始蛋白水解产生长A¿肽，然后每 3 个残基裂解，但发生这种情况的机制尚不清楚。 β-分泌酶产生的 ? 切割对于每 3 个残基的修剪至关重要，为了检验这一假设，我们将检查长 A¿ 的 C 端酰胺的能力。 (3) 导致阿尔茨海默氏症的 PS1 突变对长 A¿ 的修剪有什么影响？我们已经证明，这种 PS1 突变型 β-分泌酶复合物可以增加长 A 与短 A 的比例来自重组 APP 底物的肽在这里，我们将测试 A¿ 的转化。 49 和 A¿ 48 通过这些突变蛋白酶复合物，检查A¿我们发现，致病的 PS1 突变增加了长 A 的比例。一般来说，通过减慢修剪过程来去除肽。 公共健康相关性：该项目的目标是了解β-分泌酶，这是一种对阿尔茨海默病起因至关重要的复杂酶，建议进行生化实验来检验有关这种酶如何发挥作用以及其在阿尔茨海默病中如何失调的假设。