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（由应用程序提供）：淀粉样蛋白（a。）与阿尔茨海默氏病（AD）的发病机理相关，是由淀粉样蛋白前体（APP）的顺序裂解形成的。 ？ - 分泌酶切割App transmbrane域在？站点，生产A字的C末端，以及在？位点，产生APP内细胞内结构域的N端。该项目的目的是了解 - 神酶复合物修剪长的肽中间体中间形式的过程以及导致PS突变的疾病如何改变活性的过程。考虑到这些目标，将解决以下特定问题：（1）通过修剪特定的长A肽产生哪些较短的A肽？我们将识别并量化从正常形成的所有A肽？乳沟产品Aa笔49和a€48。我们还将确定是否不是？50？正常的切割产物会导致形成原本未观察到的a¿47，a¿44和a¿41。结果将有助于回答一个问题，即每3个残留物修剪是否是一般规则，如果是这样，则该规则是多么刚性。 （2） - 分泌酶完成的长A肽中间体的C末端三肽修剪？证据支持最初？蛋白水解产生长的A肽，然后每3个残基裂解，但是发生这种情况的机制尚不清楚。我们假设生产的新成立的羧基末端是吗？通过？分泌酶的裂解对于修剪至关重要，每3个残留物具有明显的精度。为了检验这一假设，我们将研究长A肽的C末端酰胺作为底物的能力。 （3）引起阿尔茨海默氏症的PS1突变对长A肽的修剪有什么影响？我们已经表明，这种PS1突变剂？ - 分泌酶复合物可以增加重组APP底物的长短A肽的比例。在这里，我们将通过这些突变蛋白酶复合物测试A€49和A a 48的转化，检查形成的A型产物，这些产物的比例及其相对于野生型复合物的形成速率。我们假设引起疾病的PS1突变通过减慢整体修剪过程来增加长A肽的比例。 公共卫生相关性：该项目的目的是了解？ - 分泌酶，这是对阿尔茨海默氏病至关重要的复杂酶。提出了生化实验，以检验有关该酶的工作原理以及在阿尔茨海默氏病中如何失调的假设。