KCa2 Channel Activators for Opioid Use Disorder

摘要 人类和啮齿动物的数据都显示小电导，钙离子， 在吗啡和酒精依赖的背景下激活钾通道KCa2.2（SK 2）， 戒断表明KCa 2通道激活是治疗糖尿病的一种有前途的治疗方法 物质使用障碍和相关的合并症。为了支持这一治疗假设，KCa 2 通道激活剂减少大鼠的酒精寻求和摄入，而直接注射KCa 2通道 阻断肽apamin进入丘脑核，丘脑核是一个大脑区域， 调节戒断期间的渴望和药物寻求，增加小鼠的酒精摄入量。响应 根据HEAL Initiative RFA-DA-22-032资助机会公告，我们在此提议 进行虚拟高通量筛选，目的是鉴定新型KCa 2激活剂 没有现有的非选择性苯并噻唑型活化剂的负担的药效团 这可能会发展成为阿片类药物使用障碍（OUD）的创新治疗方法， 影响了300多万美国人 为了实施这个项目，我们将借鉴我们20年的经验， KCa通道的药物化学在我们最初开发出KCa3.1阻滞剂如TRAM-34后， 我们后来发现了混合KCa 2/3激活剂SKA-31和KCa 3.1选择性激活剂SKA-121 SKA-111所有这些化合物，已被广泛用于该领域的探测， KCa通道的生理和病理生理作用，设计使用经典的药物， 化学方法没有任何结构的洞察力。然而，麦金农实验室最近 发表了KCa通道在封闭和两种开放状态下的全长低温EM结构， 现在有一个高质量的结构模板，可用于虚拟筛选新的KCa2.2通道 调节剂，可用作药理学探针，并作为药物设计的线索， 治疗OUD。在Aim-1中，我们将通过虚拟验证我们基于KCa3.1的KCa2.2同源性模型， 在两个激活剂结合口袋中筛选2000种FDA批准的化合物， 通过电生理学和诱变证实命中。在Aim-2中，我们将执行虚拟高 使用机器学习（ML）对更大的130，000个化合物库进行筛选（vHTS） 用于姿势分类和结合亲和力预测的技术。这两个目标合在一起， 1）识别可用于OUD的临床使用药物的潜力，以及2） 发现新的KCa2.2激活剂药效团，可以作为结构的模板- 基于药物化学的优化，旨在用一种新的 作用机制。

Abstract Both human and rodent data showing reduced expression of the small-conductance, calcium- activated potassium channel KCa2.2 (SK2) in the context of morphine and alcohol dependence and withdrawal suggest KCa2 channel activation as a promising therapeutic approach for the treatment of substance use disorders and associated comorbidities. In support of this therapeutic hypothesis, KCa2 channel activators reduce alcohol seeking and intake in rats, while direct injection of the KCa2 channel blocking peptide apamin into the nucleus accumbens, a brain region which plays a crucial role in regulating craving and drug seeking during abstinence, increases alcohol intake in mice. In response to the HEAL Initiative RFA-DA-22-032 Funding Opportunity Announcement, we are here proposing to perform virtual high-throughput-screening with the goal of identifying novel KCa2 activator pharmacophores that are free of the liabilities of the existing unselective benzothiazole-type activators and that could be developed into innovative treatments for opioid use disorders (OUD), a condition that affects more than 3 million Americans. For the implementation of this project, we will draw on our 20 years of experience with the medicinal chemistry of KCa channels. After we initially developed KCa3.1 blockers such as TRAM-34, we later discovered the mixed KCa2/3 activator SKA-31, and the KCa3.1 selective activators SKA-121 and SKA-111. All these compounds, which have been widely used in the field to probe the physiological and pathophysiological roles of KCa channels were designed using classical medicinal chemistry approaches without any structural insight. However, the MacKinnon laboratory recently published the full-length cryo-EM structure of a KCa channel in the closed and two open states and we now have a high-quality structural template available to virtually screen for novel KCa2.2 channel modulators that could be used as pharmacological probes and as leads for the design of drugs for the treatment of OUD. In Aim-1, we will validate our KCa3.1-based KCa2.2 homology model by virtually screening 2000 FDA-approved compounds in two activator binding pockets and experimentally confirm the hits by electrophysiology and mutagenesis. In Aim-2, we will perform a virtual High Throughput Screen (vHTS) of a larger, 130,000-compound library with machine learning (ML) techniques for pose classification and binding affinity prediction. Taken together, these two aims have the potential of 1) identifying a clinically used drug that could be repurposed for OUD and 2) discovering novel KCa2.2 activator pharmacophores that could serve as templates for structure- based-medicinal chemistry optimization aimed at developing OUD treatments with a novel mechanism of action.