Network Medicine for Alzheimers Disease: Functional Dissection and Pharmacologic Perturbation of a Human Brain Synaptic Regulatory Expression Signature

项目摘要 对人脑转录组图谱的分析构成了一种强有力的策略， 与阿尔茨海默病（AD）病理生理学相关的网络。与加速 药物伙伴关系（AMP）-AD联盟，我们已经定义了有前途的分子网络失调， AD基于对约2，000份人脑尸检样本的RNA测序分析。在便转化 对于“网络疗法”的这些结果，计算预测必须在实验中进行严格的测试。 动物模型为了查明AD相关共表达网络中的因果驱动因素，357 使用转基因果蝇系统地筛选了保守的靶点，鉴定了144种修饰剂， 人淀粉样蛋白-β（A β）和/或tau触发的神经元功能障碍。我们的研究结果显示了一个有希望的167- 基因突触调节网络（SRN）与谷氨酸兴奋性信号传导有关，这两个方面（i）显著 在AD中下调，和（ii）在AD中基于敲低而富集神经变性的抑制因子。 果蝇此外，GRIN 2B，一种NMDA受体亚基和批准的AD药物美金刚的靶点， 一个“中枢”抑制器。我们假设SRN代表了一个高度保守和协调的 转录保护反应，补偿兴奋毒性神经元损伤的AD，一致 有证据表明，过度兴奋和受损的突触可塑性是疾病的重要因素 发病机制和临床表现。我们建议在这里部署我们强大的跨物种策略， 完善这一机制假设，并开发药理学方法来提高SRN，从而支持 AD中的大脑弹性首先，（AIM 1），我们将进行系统的遗传操作，以模拟向上或向下- 调节数百个SRN基因，筛选tau蛋白或Akt蛋白诱导的、年龄相关的 依赖性神经元功能障碍。有希望的命中将使用独立的测定进行验证， 随机化将确认SRN人类基因表达变化对AD风险或保护的因果影响。 接下来（AIM 2），我们将对GRIN 2B和其他确定的SRN因果驱动因素进行遗传操作， 兴奋性毒性神经元损伤的果蝇模型，沿着小鼠原发性 海马神经元培养。最后（AIM 3），我们将实验性地探索精细规模的SRN架构， 在两种细胞中，在推断的节点驱动基因的遗传扰动后测定转录特征， 是否存在兴奋性毒性和其他AD病理触发因素。我们将提名小分子 在人类神经元培养物中进行实验验证。影响：我们的整合，跨物种 方法将功能解剖一个有前途的转录调控网络，使用强大的，在体内测定， 绘制AD兴奋毒性神经元损伤的复杂分子结构， 具有保护突触健康潜力的药理学重编程节点。

PROJECT SUMMARY Analyses of transcriptomic profiles from human brains constitute a powerful strategy for highlighting biological networks associated with Alzheimer’s disease (AD) pathophysiology. In collaboration with the Accelerating Medicines Partnership (AMP)-AD Consortium, we have defined promising molecular networks dysregulated in AD based on analyses of RNA-sequencing from ~2,000 human brain autopsy samples. In order to translate these results for “network therapies”, computational predictions must be rigorously tested in experimental animal models. In order to pinpoint causal drivers among AD-associated coexpression networks, 357 conserved targets were systematically screened using transgenic Drosophila, identifying 144 modifiers of human amyloid-beta (Aß)- and/or tau-triggered neuronal dysfunction. Our results highlight a promising 167- gene synaptic regulatory network (SRN) linked to glutamate excitatory signaling that is both (i) significantly down-regulated in AD and (ii) enriched for suppressors of neurodegeneration based on knockdown in Drosophila. Moreover, GRIN2B, an NMDA receptor subunit and target of the approved AD drug, memantine, is a “hub” suppressor. We hypothesize that SRN represents a highly conserved and coordinated transcriptional protective response that compensates for excitotoxic neuronal injury in AD, consistent with evidence that hyperexcitability and impaired synaptic plasticity are important contributors to disease pathogenesis and clinical manifestations. We propose here to deploy our powerful cross-species strategy to refine this mechanistic hypothesis and develop a pharmacologic approach to boost SRN and thereby support brain resilience in AD. First, (AIM1), we will perform systematic genetic manipulations to simulate up- or down- regulation in hundreds of SRN genes and screen for enhancers and suppressors of tau- or Aß-induced, age- dependent neuronal dysfunction. Promising hits will be validated using independent assays, and Mendelian randomization will confirm the causal impact of SRN human gene expression changes on AD risk or protection. Next (AIM2), we will perform genetic manipulations of GRIN2B and other identified SRN causal drivers in Drosophila models of excitotoxic neuronal injury, along with complementary studies in mouse primary hippocampal neuron cultures. Lastly (AIM3), we will experimentally probe fine-scale SRN architecture, assaying transcriptional signatures following genetic perturbations of inferred nodal driver genes in both the presence or absence of excitotoxicity and other AD pathologic triggers. We will then nominate small molecule perturbagens for experimental validation in human neuronal cultures. IMPACT: Our integrative, cross-species approach will functionally dissect a promising transcriptional regulatory network using powerful, in vivo assays, mapping the complex molecular architecture of AD excitotoxic neuronal injury and pinpointing vulnerable nodes for pharmacologic reprogramming with potential to preserve synaptic health.