TREM2-endogenous ligand interactions in Alzheimer disease

项目摘要 在髓样细胞上表达的触发受体2（TREM 2）中的单个氨基酸变体已经被发现。 通过全基因组关联研究确定为迟发性脑梗死最强的遗传风险因素之一， 阿尔茨海默病（AD）。TREM 2中的AD相关变体损害TREM 2结合和信号传导的能力， 对内源性配体的反应。TREM 2在AD中的分子机制尚不完全清楚， 理解，部分原因是缺乏TREM 2的内源性配体的决定性身份和缺乏 很好地理解不同的内源性配体如何与TREM 2相互作用以影响TREM 2 功能协调发展的核心假设是TREM 2碱性位点的AD相关变体与AD相关的基因变构。 调节TREM 2疏水位点结合的内源性配体，并通过 在碱性和疏水结合位点的内源性配体可以增强TREM 2的免疫活性 在AD中。目的是鉴定结合在碱性和/或疏水性位点的内源性配体， TREM 2，确定在任一结合位点处配体结合的变构效应，并确定 AD相关TREM 2变体对与TREM 2结合的内源性配体的影响。我们将检验这个假设 实现三个目标。目的1是鉴定碱性磷酸酶的内源性配体， TREM 2上的疏水结合位点。目的二是确定内源性配体的变构效应 在两个TREM 2结合位点结合。目的3是确定AD相关的TREM 2变体对AD的影响。 内源性配体与TREM 2的结合。 新知识可能会对AD研究和治疗产生很大影响， 靶向TREM 2碱性和疏水位点以鉴定TREM 2内源性配体的途径， 以促进TREM 2调节的免疫激活。研究成果可以帮助开发新的 治疗策略，如联合药物治疗，以增强TREM 2介导的细胞活性 并通过AD相关变体补偿TREM 2功能的损失以用于AD治疗。虽然 本研究直接潜在应用是AD发病机制、对其他神经变性的影响， 受TREM 2活化影响的炎性疾病可能是巨大的。 创新包括：1）这将是第一项通过靶向TREM 2和TREM 2内源性配体来鉴定TREM 2内源性配体的研究。 使用组合的计算机模拟以更确定的方式分析TREM 2碱性和疏水性结合位点。 虚拟筛选，生物物理和生物实验; 2）结果将揭示新的发现，AD- TREM 2碱性位点的相关变体变构调节TREM 2结合的内源性配体 疏水位点，以及内源性配体在碱性和疏水位点处的变构共刺激 可以增强AD中TREM 2调节的免疫活性，为AD的病因学提供了新的见解。

PROJECT SUMMARY Single amino acid variants in triggering receptor expressed on myeloid cells 2 (TREM2) have been identified by genome-wide association studies to be one of the strongest genetic risk factors for late-onset Alzheimer’s disease (AD). AD-associated variants in TREM2 impair TREM2’s ability to bind and signal in response to endogenous ligands. The molecular mechanisms of TREM2 in AD remain not fully understood, in part due to the lack of conclusive identities for TREM2’s endogenous ligands and the lack of a good understanding of how different endogenous ligands interact with TREM2 to affect TREM2 functions. The central hypothesis is that AD-associated variants at TREM2 basic site allosterically regulate endogenous ligands bound at the hydrophobic site of TREM2, and allosteric co-stimulation by endogenous ligands at both basic and hydrophobic binding sites could enhance TREM2 immune activity in AD. The objective is to identify endogenous ligands that bind at the basic and/or hydrophobic sites of TREM2, determine the allosteric effects of ligand binding at either binding site, and determine the effect of AD-associated TREM2 variants on endogenous ligands binding to TREM2. We will test the hypothesis and implement the objective with three Aims. Aim 1 is to identify endogenous ligands of the basic and hydrophobic binding sites on TREM2. Aim 2 is to determine the allosteric effects of endogenous ligand binding at both TREM2 binding sites. Aim 3 is to determine the effect of AD-associated TREM2 variants on endogenous ligands binding to TREM2. New knowledge could have high impact for AD research and treatment by opening an unrecognized avenue of targeting both TREM2 basic and hydrophobic sites to identify TREM2 endogenous ligands and to promote TREM2-regulated immune activation. Research outcomes could aid the development of novel therapeutic strategies, such as combined drug therapy, to enhance TREM2-mediated cellular activities and to compensate the loss of TREM2 function by AD-associated variants for AD treatment. Although immediate potential application for this study is AD pathogenesis, impact on other neurodegenerative and inflammatory diseases affected by TREM2 activation may be enormous. Innovations include 1) this will be the first study to identify TREM2 endogenous ligands by targeting both TREM2 basic and hydrophobic binding sites in a more conclusive manner using the combined in silico virtual screening, biophysical and biological experiments; 2) Results will unveil novel findings that AD- associated variants at TREM2 basic site allosterically regulate endogenous ligand bound at TREM2 hydrophobic site, and allosteric co-stimulation by endogenous ligands at both basic and hydrophobic sites could enhance TREM2-regulated immune activity in AD, providing novel insight into etiology of AD.