Characterizing and Targeting Pyk2 Kinase in Alzheimer’s Disease

摘要 阿尔茨海默病(AD)认知功能障碍的主要病理生理学机制是神经元突触丢失 存活的突触的可塑性受损。干预阿尔茨海默病的治疗努力主要集中在 多肽是突触疾病的上游触发因素，但到目前为止，临床试验一直令人失望。 AD治疗需要更多有效的靶点，特别是那些更直接专注于突触的靶点 赤字。 就其本质而言，晚发性AD(负荷)风险的遗传学研究具有直接的临床相关性。最大的 Gwas对负荷的分析确定了其常见变异会改变风险的基因的简短列表，提供了潜在的 AD治疗的新靶点。我们考虑了其中是否有可能与突触有直接联系 阿尔茨海默病的功能障碍。几乎所有的负荷风险基因都被假设与A？结合，改变A？新陈代谢， 调节细胞内吞作用，或调节免疫功能。因此，它们对突触功能障碍的作用 必须被认为是间接的，通过Aü水平或通过对病理的免疫反应。从阿尔茨海默病基因列表中 PYK2(也叫PTK2B或FAK2)是目前已知的唯一编码一种蛋白的基因，这种蛋白集中在 突触密度对突触可塑性有直接影响。在这里，我们试图评估Pyk2在AD中的作用 从基因和机制上，并评估该蛋白质作为专注于突触的治疗目标 功能障碍。 在此之前，我们已经研究了A？寡聚体(A？o)对神经元毒性的生化基础，以及这些研究 也牵连到了Pyk2。使用一种无偏见的全基因组筛选方法，我们搜索了A？寡聚体- 特异性结合位点在脑内表达，并鉴定PrPC。我们定义了A？o-PrPC-mGluR5-Fyn级联 这会损害AD模型中的突触。重要的是，Pyk2蛋白与mGluR5和mGluR5物理上相关 Fyn，以及与突触可塑性有关。 我们将评估Pyk2对人类家族性AD转基因表现的重要性这一假设 小鼠的表型，我们将评估人类AD样本中的Pyk2失调。我们还将针对 酶的药理作用。这些研究有可能将一种有效的负荷遗传风险与 阿尔茨海默病的突触功能障碍，可能与A？o-PrPC-mGluR5-Fyn级联反应有关。 重要的是，这些数据可能会指导开发针对突触Pyk2通路的药理学工具 对阿尔茨海默病进行治疗干预。

SUMMARY Central to the pathophysiology of cognitive dysfunction in Alzheimer's disease (AD) is loss of synapses with an impairment of plasticity at surviving synapses. Therapeutic efforts to intervene in AD have focused on the Aß peptide as an upstream trigger for synaptic disease, but clinical trials have been disappointing so far. Additional validated targets for AD therapy are needed, in particular those focused more directly on synaptic deficits. By their very nature, genetic studies of Late Onset AD (LOAD) risk are of direct clinical relevance. The largest GWAS analysis of LOAD identified a short list of genes whose common variants alter risk, providing potential new targets for AD therapy. We considered whether any of these might be directly linked to synaptic dysfunction in AD. Nearly all of the LOAD risk genes are hypothesized to bind Aß, to alter Aß metabolism, to regulate cellular endocytosis, or to modulate immune function. Therefore, their action on synaptic dysfunction must be considered indirect, via Aß levels or via the immune reaction to pathology. From the list of AD genetic risk factors, Pyk2 (also PTK2B or FAK2) is the only gene recognized to encode a protein concentrated at post- synaptic densities with direct effects on synaptic plasticity. Here, we seek to assess the role of Pyk2 in AD genetically and mechanistically, and to evaluate the protein as a therapeutic target focused on synaptic dysfunction. Previously, we have studied the biochemical basis for Aß oligomer (Aßo) toxicity in neurons and these studies have also implicated Pyk2. Using an unbiased genome-wide screening method we searched for Aß oligomer- specific binding sites expressed in brain, and identified PrPC. We defined an Aßo–PrPC–mGluR5–Fyn cascade that damages synapses in AD models. Importantly, the Pyk2 protein physically associates with mGluR5 and Fyn, as well as being implicated in synaptic plasticity. We will evaluate the hypothesis that Pyk2 is essential for manifestations of human familial AD transgene phenotypes in mice, and we will assess Pyk2 dysregulation in human AD samples. We will also target the enzyme pharmacologically. These studies have the potential to couple a validated LOAD genetic risk to synaptic dysfunction in AD, and may establish a connection with the Aßo–PrPC–mGluR5–Fyn cascade. Critically, these data may guide attempts to develop pharmacological tools to target the synaptic Pyk2 pathway for therapeutic intervention in AD.