Probes to differentiate AD brain beta-amyloid from model beta-amyloid systems

描述（由申请人提供）：阿尔茨海默病（AD）的动物模型概括了人类疾病的早期阶段，但不包括神经元死亡和痴呆的后期阶段。这些模型在组织学上发展为相似但可区分的A -淀粉样蛋白病理。成像配体Pittsburgh Compound B （PIB）结合来自人、动物和合成系统的不溶性A β，具有nM亲和力。然而，PIB与人类AD大脑结合的化学计量比动物模型或合成A β原纤维大约500至10,000倍。其他A - β配体，如硫黄素S和刚果红，对人类、动物和合成A - β原纤维没有区别。我们假设人类大脑和动物A β原纤维之间PIB结合的差异是人类AD神经元死亡和痴呆机制的一部分，并导致动物模型中缺乏完整的疾病再现。初步数据表明，除了A β外，AD大脑中PIB的高结合化学计量还需要未表征的生化成分，该成分存在于抗变性组装中。这项工作将为人类A β PIB结合位点生成光亲和探针，该探针还包含一个标签，以实现亲和纯化，我们将利用这些探针通过质谱分析来亲和分离和鉴定AD大脑中与PIB配体接触的蛋白质和脂质成分。具体目标合成并优化一系列对人类AD大脑PIB结合位点具有选择性的光亲和配体及其亲和标签手柄。具体目标2。利用MR-PIB和质谱鉴定形成AD脑PIB配体结合位点的蛋白质和脂质成分。该项目的长期目标是利用已鉴定的人类AD - A β纤维及其PIB配体结合袋的成分和结构，深入了解导致AD的人类AD - A β组件的独特特性。最终，我们将确定人类和AD动物模型之间的差异，以阐明AD相关的细胞和环境机制，这将为动物模型的改进提供信息，并确定潜在的新型药物靶点。

DESCRIPTION (provided by applicant): Animal models of Alzheimer's disease (AD) recapitulate early phases of the human condition, but not the later stages of neuronal death and dementia. These models develop histologically similar, but distinguishable A beta amyloid pathology. The imaging ligand Pittsburgh Compound B (PIB) binds insoluble A beta from human, animal and synthetic systems with nM affinity. However, the stoichiometry of PIB binding to human AD brain is approximately 500- to 10,000-fold greater than that in animal models or synthetic A beta fibrils. Other A beta ligands such as Thioflavin S and Congo Red do not discriminate between human, animal, and synthetic A beta fibrils. We hypothesize that the difference in PIB binding between human brain and animal A beta fibrils is integral to the mechanism of neuronal death and dementia in human AD, and contributes to the lack of complete recapitulation of the disease in animal models. Preliminary data indicate that uncharacterized biochemical components in addition to A beta are required for the high binding stoichiometry of PIB in AD brain, which resides in a denaturation-resistant assembly. The proposed work will generate photoaffinity probes for the human A beta PIB binding site that also contain a tag to enable affinity purification and we will utilize these probes to affinity isolate nd identify protein and lipid components contacting the PIB ligand in the AD brain by mass spectral analysis. Specific Aim 1. Synthesize and optimize a series of photoaffinity ligands with handles for affinity tags that are selective for the PIB binding site of human AD brain. Specific Aim 2. Identify the protein and lipid components that form the PIB ligand binding site of AD brain using MR-PIB and mass spectrometry. The long term goal of this project is to use the identified components and structure of the human AD A beta fibril and its PIB ligand binding pocket to provide insight into unique properties of human AD A beta assemblies that contribute to AD. Ultimately we will determine the differences between human and AD animal models A beta assemblies to elucidate AD-related cellular and environmental mechanisms that will inform the improvement of animal models and identify potential novel drug targets.