Discovery of novel small molecule antidepressants

重度抑郁症（Major Depression Disorder，MDD）是最常见的精神疾病之一，影响着数百万人 世界各地的人们。大多数可用于治疗MDD的药物靶向涉及单胺能神经元的脑通路。 神经传递素尽管有这些治疗，多达百分之五十的患者没有改善反应 现有的疗法。超极化激活的环核苷酸门控（HCN）通道介导Ih，a 对控制神经元兴奋性和整合来自其他大脑的突触输入至关重要的电流 地区HCN受其辅助亚基TRIP 8b（含有Rab 8b的四肽重复序列）的严格调控。 相互作用蛋白），其负责将HCN运输到神经元表面，并且仅在神经元中表达。 大脑我们的实验室和其他人已经观察到，通过基因缺失或基因缺失导致的HCN通道功能丧失， 或通过干扰TRIP 8b功能导致抗抑郁药样表型。除了在大脑中的作用， HCN对中枢神经系统以外的许多功能至关重要，包括心脏的节律发生。 这个关键的HCN功能混淆了以前在MDD中全球目标HCN的努力。我们有 开发了一种新的方法，通过靶向HCN/TRIP 8b来发现新的潜在抑郁症治疗方法 与小分子的相互作用。我们建立了一个高通量的荧光偏振（FP） 筛选测定以及二级测定以鉴定HCN/TRIP 8b抑制剂。我们已经验证了我们的 通过测试不同的小分子文库进行初步筛选试验，并进一步验证了几种 这些命中在正交测定中以确认靶接合和效力。同时，基于 已知的TRIP 8b X射线晶体结构，我们已经进行了一个试点在硅片屏幕和验证了几个 在我们的生化检测中找到了结果鉴定具有改善的效力和功效的抑制剂， 化合物更适合探针优化，我们建议进行扩大湿和在硅高- 利用我们建立的初级和次级测定进行通量筛选。在具体目标1中，我们将使用 我们的FP测定法测试了235，000种不同小分子的文库，以确定其破坏HCN/TRIP 8b的能力 约束力我们还将使用我们的计算机协议来筛选1800万化合物锌数据库，并验证 通过FP测定法将所得结构作为抑制剂。在具体目标2中，我们将评估我们命中的效力 使用合理的一系列体外筛选测定，包括荧光热位移（FTS），AlphaScreen， 和谷胱甘肽S-转移酶（GST）下拉实验。最后，在具体目标3中，我们建议评估 我们的命中物在一系列基于细胞的测定（包括流式细胞术）中的功能活性， 免疫细胞化学和电生理学。这一提议代表了一种治疗MDD的新方法， 我们发现的小分子将广泛用于开发新的治疗方法， 医学需要以及探索HCN通道和TRIP 8b在抑郁症中的参与。

Major depressive disorder (MDD) is the one of the most common psychiatric diseases, and affects millions of people worldwide. Most drugs available to treat MDD target brain pathways involving monoaminergic neurotransmitters. Despite these therapies, as many as fifty percent of patients do not improve in response to existing therapies. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate Ih, a current that is critical for controlling neuronal excitability and integration of synaptic inputs from other brain regions. HCN is tightly regulated by its auxiliary subunit, TRIP8b (tetratricopeptide repeat-containing Rab8b- interacting protein), which is responsible for trafficking HCN to the neuronal surface and is only expressed in the brain. Our lab and others have observed that loss of HCN channel function through either genetic deletion or by interfering with TRIP8b function leads to an antidepressant-like phenotype. Beyond its role in the brain, HCN is crucial for many functions outside the central nervous system, including rhythmogenesis in the heart. This crucial HCN function has confounded previous efforts to globally target HCN in MDD. We have developed a novel approach to discover new potential depression therapeutics by targeting HCN/TRIP8b interaction with small molecules. We have established a high throughput fluorescence polarization (FP) screening assay as well as secondary assays to identify HCN/TRIP8b inhibitors. We have validated our primary screening assay by testing a diverse library of small molecules and have further validated several of these hits in orthogonal assays to confirm target engagement and potency. Simultaneously, based on the known TRIP8b x-ray crystal structure, we have carried out a pilot in silico screen and verified several of the resulting hits in our biochemical assays. To identify inhibitors with improved potency and efficacy and find compounds more suitable for probe optimization, we propose to carry out expanded wet and in silico high- throughput screening utilizing our established primary and secondary assays. In specific aim 1, we will use our FP assay to test a library of 235,000 diverse small molecules for their ability to disrupt HCN/TRIP8b binding. We will also use our in silico protocols to screen the 18 million compound Zinc database and verify the resulting structures as inhibitors by the FP assay. In specific aim 2, we will assess the potency of our hits using a rational series of in vitro screening assays including fluorescence thermal shift (FTS), AlphaScreen, and glutathione S-transferase (GST) pulldown experiments. Finally, in specific aim 3, we propose to evaluate the functional activity of our hits in a series of cell-based assays including flow cytometry, immunocytochemistry, and electrophysiology. This proposal represents a novel approach to treat MDD and the small molecules that we discover will be broadly useful in developing new therapeutics for this unmet medical need as well as for probing the involvement of HCN channels and TRIP8b in depression.