Discovery of allosteric activators of phospholipase C-gamma2 to treat Alzheimer's disease

摘要 目前阿尔茨海默病（AD）的治疗方法不能逆转，甚至不能减缓疾病的进展。 这种情况是可怕的，并加剧了针对两个更有希望的抗体的失败。 磷酸化tau蛋白和β-淀粉样蛋白-来治疗这种疾病。显然，新的治疗方法是迫切的， needed. 2017年，一项大型全基因组研究将PLCG 2的一种天然变体（P522 R） 编码PLC-1002，具有防止迟发性AD的保护作用。在后续研究中，这种遗传关联仍然存在， 强大且可重复性高。更令人鼓舞的是，在对轻度认知障碍患者的临床研究中， 携带PLCG 2（P522 R）的人与非携带者相比，认知能力下降的速度较慢。 甚至在ApoE 4纯合子患者中也观察到了保护作用，ApoE 4是一种与AD密切相关的生物标志物。在 在大脑中，PLC-102主要表达于小胶质细胞中，在那里它控制吞噬和神经炎症 流程.它在AD患者的病理区域中表达更高。在小胶质细胞中，PLC-102被激活， TREM 2（其使用ApoE 4作为配体）和CSF 1 R两者的下游，两种跨膜受体， 与AD密切相关。类似地，PLC-β 2激活PKC β 2，而PKC β 2也与AD相关.因此，基因和细胞 数据强烈支持PLC-102作为治疗AD的新治疗靶点。 PLC-102（P522 R）的磷脂酶活性相对于其野生型对应物适度升高， 正是这种小胶质细胞活性的增加被普遍认为可以预防AD。我们建议确定 并优化选择性激活PLC-2的小分子，以重现PLC-2的神经保护作用。 P522 R的表达，治疗AD。该研究计划依赖于两种互补的高通量测定， 荧光底物的真核PLC，我们发明了明确的这项研究。因此，我们将 追求三个目标。在目标1中，将对总计约300，000种化合物的内部收集进行活化剂筛选 的PLC-PLC 2和初步命中验证的活性，选择性，组成和纯度;将使用化学信息学 对命中进行结构分类。在Aim 2中，全长PLC-102的高质量模型与分子动力学耦合， 模拟将用于数千万种化合物的计算筛选。在目标3中，一套 生物化学、生物物理学和细胞生物学研究将用于优先考虑PLC-12的变构激活剂， 良好的化学和药理学性质。这些新颖的小分子将是宝贵的工具， 进一步了解PLC-102（P522 R）如何降低AD的风险。这些小分子也将被用作 用于开发治疗AD的新疗法。

ABSTRACT Current therapies for Alzheimer’s disease (AD) do not reverse, or even slow, progression of the disease. This situation is dire and exacerbated by the failure of antibodies directed toward two of the more promising targets—phosphorylated tau and beta-amyloids—to treat the disease. Clearly, new treatments are urgently needed. In 2017, a large genome-wide study associated a naturally-occurring variant (P522R) of PLCG2, the gene encoding PLC-2, with protection from late onset AD. In follow-up studies, this genetic association has remained strong and highly reproducible. Even more encouraging, in clinical studies of patients with mild cognitive impairment, people that carried PLCG2 (P522R) had slower rates of cognitive decline compared to non-carriers. Protection was observed even for patients homozygous for ApoE4, a biomarker strongly linked to AD. In the brain, PLC-2 is primarily expressed in microglial cells where it controls phagocytic and neuroinflammatory processes. It is more highly expressed in pathological areas of patients with AD. In microglia, PLC-2 is activated downstream of both TREM2 (which uses ApoE4 as a ligand) and CSF1R, two transmembrane receptors that are strongly linked to AD. Similarly, PLC-2 activates PKC, which is also linked to AD. Thus, genetic and cellular data strongly support PLC-2 as a novel therapeutic target for treatment of AD. The phospholipase activity of PLC-2 (P522R) is modestly elevated relative to its wild-type counterpart and it is this increased activity in microglia that is generally accepted to protect against AD. We propose to identify and optimize small molecules that selectively activate PLC-2 to reproduce the neuroprotective effects of PLC- 2 (P522R) and treat AD. The research plan relies on complementary high-throughput assays enabled by two fluorogenic substrates for eukaryotic PLCs that we invented explicitly for this research. Consequently, we will pursue three Aims. In Aim 1, in-house collections totaling ~300,000 compounds will be screened for activators of PLC-2 and primary hits verified for activity, selectivity, composition, and purity; cheminformatics will be used to structurally classify hits. In Aim 2, a high-quality model of full-length PLC-2 coupled with molecular dynamics simulations will be used for computational screens of tens of millions of compounds. In Aim 3, a suite of biochemical, biophysical, and cell biological studies will be used to prioritize allosteric activators of PLC-2 with favorable chemical and pharmacological properties. These novel small molecules will be invaluable tools to further understand how PLC-2 (P522R) reduces the risk of AD. The small molecules will also be used as leads for the development of novel therapeutics to treat AD.