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

项目总结 对人脑转录图谱的分析构成了突出生物学特征的有力策略 与阿尔茨海默病(AD)病理生理学相关的网络。与加速的 药物伙伴关系(AMP)-AD联盟，我们定义了有希望的分子网络在 AD基于对约2,000个人脑尸检样本的RNA测序分析。为了翻译 这些结果对于“网络疗法”来说，计算预测必须在实验中得到严格的检验。 动物模型。为了精确定位AD相关共表达网络中的因果驱动因素，357 利用转基因果蝇系统地筛选了保守的靶标，鉴定了144个修饰物 人类淀粉样β蛋白(A？)和/或tau引发的神经元功能障碍。我们的结果突出了有希望的167- 与谷氨酸兴奋性信号相关的基因突触调节网络(SRN)：(I)显著 AD中下调和(Ii)基于基因敲除的神经退行性变抑制因子的丰富 果蝇。此外，被批准的AD药物美金刚的靶点和NMDA受体亚单位GRIN2B是 一个“中枢”抑制器。我们假设SRN代表一个高度保守和协调的 AD中补偿兴奋性毒性神经元损伤的转录保护反应，一致 有证据表明，过度兴奋和突触可塑性受损是导致疾病的重要因素 发病机制及临床表现。我们在这里建议将我们强大的跨物种战略部署到 完善这一机制假说，并开发一种药理学方法来增强SRN，从而支持 阿尔茨海默病的脑部韧性。首先，(AIM1)，我们将执行系统的遗传操作来模拟向上或向下- 对数百个SRN基因的调控和筛选tau或Aç诱导的AGE- 依赖性神经元功能障碍。有希望的命中将使用独立的分析和孟德尔 随机化将证实SRN人类基因表达变化对AD风险或保护的因果影响。 接下来(AIM2)，我们将执行GRIN2B和其他已识别的SRN原因驱动因素的遗传操作 小鼠兴奋性中毒性神经元损伤的果蝇模型及补充研究 海马神经元培养。最后(AIM3)，我们将对精细规模的SRN体系结构进行实验探索， 检测在推测的结节驱动基因的遗传扰动后的转录特征 是否存在兴奋性毒性和其他AD病理诱因。然后我们将提名小分子 用于人类神经元培养的实验验证的微扰剂。影响：我们的一体化、跨物种 方法将使用强大的体内分析从功能上剖析一个有前景的转录调控网络， AD兴奋性中毒性神经元损伤的复杂分子结构定位及易损性 用于药物重新编程的节点，具有保护突触健康的潜力。

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.