Malaria melatonin receptor signaling as a novel drug target

描述(申请人提供)：疟疾是第三世界发病率和死亡率的主要原因，疟原虫对抗疟疾治疗的抗药性是一个严重且日益严重的问题。迫切需要新的药物靶点和治疗方法，但这是制药业资源不足的问题。这项建议的目的是验证疟疾信号通路作为新的药物靶点，使用的子集 一家主要制药公司最近发布的具有抗疟疾活性的化合物，以及一组相关的化合物，已经被验证可用于其他临床用途。提出的靶点是疟疾褪黑激素受体(PMTR)，它被认为可以颠覆宿主激素褪黑素，以调节寄生虫的增殖，并使疟原虫的细胞周期与宿主的昼夜节律同步。确认pMTR作为小分子药物治疗的潜在靶点将代表着一种范式的转变，无论是在已确定的新途径方面，还是在拟议的治疗作用机制方面。目前的工作集中在恶性疟原虫感染的红细胞(RBC)阶段，这是导致主要疾病症状的原因，包括贫血、脑型疟疾、多器官衰竭以及更重要的是，每48小时发生一次周期性发热。我们之前的研究已经提供了证据，褪黑素可以启动涉及第二信使IP3的细胞内钙信号级联，导致寄生虫血症增加，并刺激细胞周期的进展。我们假设，疟原虫褪黑激素受体(PMTR)代表了一种新的抗疟疾药物靶点，以减少RBC周期的增殖和同步化。该项目的具体目标是：1.验证pMTR作为一个潜在的小分子化学靶点，并评估可能的pMTR调节剂对恶性疟原虫增殖和同步化的影响。这些研究将确定一个初步的活性图谱，并阐明药物作用的机制，同时提供有关pMTR信号通路的更多信息。2.开发化学探针衍生的亲和试剂来鉴定pMTR蛋白，最终目的是注释和克隆该基因。3.确定pMTR调节剂与公认的抗疟疾药物联合的疗效，这些药物被认为不是通过pMTR钙信号通路发挥作用的。4.用啮齿动物模型检测在AIM 1中发现的pMTR小分子抑制剂在体内的作用 为进一步评价pMTR作为潜在的小分子药物靶点的可行性。这项工作将由一个多学科团队进行，他们在钙和G蛋白信号转导方面具有专业知识， 疟疾生物学、寄生虫学、化学生物学和药物化学。技术包括活细胞荧光成像、成像流式细胞术、体内疟疾模型和合成化学。

DESCRIPTION (provided by applicant): Malaria is a leading cause of morbidity and mortality in the Third World and resistance of Plasmodium parasites to antimalarial treatments is a significant and growing problem. Novel drug targets and treatment approaches are urgently required, but this is an under-resourced problem in the pharmaceutical industry. The purpose of this proposal is to validate a malarial signaling pathway as a novel drug target, using a subset of compounds with antimalarial activity recently released by a major pharmaceutical company, together with a related group of compounds already validated for other clinical uses. The proposed target is a malarial melatonin receptor (pMTR) that is postulated to subvert the host hormone melatonin to regulate parasite proliferation and entrain the Plasmodium cell cycle to be synchronized with the host circadian rhythm. Validation of pMTR as a potential target for small molecule drug therapy would represent a paradigm shift, both in terms of the novel pathway identified and the proposed mechanism of therapeutic action. The present work is focused on the red blood cell (RBC) stage of P. falciparum infection, which is responsible for the predominant disease symptoms, including anemia, cerebral malaria, multi-organ failure and, significantly, periodic fevers that occur on a 48 h cycle. Our previous studies have provided evidence that melatonin can initiate an intracellular calcium signaling cascade involving the second messenger IP3, leading to enhanced parasitemia and stimulating progression through the cell cycle. We hypothesize that the Plasmodia melatonin receptor (pMTR) represents a novel antimalarial drug target to decrease proliferation and synchronization of the RBC cycle. The specific aims of the proposed project are: 1. To validate pMTR as a potential small molecule chemical target and assess the effects of putative pMTR modulators on P. falciparum proliferation and synchronization. These studies will determine an initial activity profile and elucidate the mechanism of drug action, while at the same time providing additional information on the pMTR signaling pathway. 2. To develop chemical probe-derived affinity reagents to identify the pMTR protein, with the eventual goal to annotate and clone the gene. 3. To determine the efficacy of pMTR modulators in combination with established antimalarial drugs that are not thought to act through the pMTR calcium signaling pathway. 4. To examine the effect of the small molecule inhibitors of pMTR identified in Aim 1 in vivo using rodent models, in order to further assess the viability of pMTR as a potential small molecule drug target. The work will be carried out by a multidisciplinary team, with expertise in calcium and G-protein signaling, malaria biology, parasitology, chemical biology and medicinal chemistry. Techniques include live-cell fluorescence imaging, imaging flow cytometry, in vivo malaria models, and synthetic chemistry.