Function and pharmacology of schistosome multidrug resistance proteins

描述（由申请人提供）：项目概述：血吸虫属吸虫扁虫是血吸虫病的病原体。新的抗线虫药物的一个潜在的生理靶点是蠕虫排泄废物和外源性物质的系统。P-糖蛋白（P-glycoprotein，Pgp）是ATP结合盒超家族的成员，是ATP依赖性的外排泵，参与毒素和外源性物质的转运。在脊椎动物中，Pgp是多药耐药1基因的产物，该基因在显示广泛耐药的肿瘤细胞中扩增并过表达。Pgp也可能在蠕虫的耐药性中发挥作用。几年前对一个染色体Pgp cDNA（SMDR 2）进行了测序，但尚未对其功能进行表征。该提案的长期目标是剖析SMDR 2和其他重要药物转运蛋白的功能作用和药理学敏感性。我们将采用钙黄绿素荧光测定法来检查表达的SMDR 2和其他转运蛋白的底物和抑制剂特异性。我们还将研究吡喹酮，目前的抗组胺药的选择，对SMDR 2的表达的影响，以及是否吡喹酮耐药菌株有改变表达的这种或其他转运蛋白。最后，我们将研究SMDR 2的遗传或药理学破坏对寄生虫的影响。该项目的具体目标是回答以下问题：1。哺乳动物细胞中表达的SMDR 2和其他多体药物转运蛋白的生化特性和底物特异性是什么？2. SMDR 2和其他多药转运蛋白的组织分布和发育特征是什么？3.暴露于PZQ等药物是否会导致SMDR 2表达或分布的变化？4.对PZQ敏感性降低的蠕虫分离株是否显示SMDR 2或其他多药转运蛋白表达水平的差异？5. SMDR 2的遗传和药理学破坏对寄生虫存活、生理学和药理学敏感性/相关性有什么影响：血吸虫病是一种由称为寄生体的寄生扁虫引起的主要热带疾病。抗血吸虫病新药的潜在生理靶点可能是从血吸虫细胞中清除废物和毒素的转运蛋白。我们建议使用几种方法来确定这样一个多体分子，P-糖蛋白，这在脊椎动物中，也参与了一系列广泛的药物的耐药性的属性。

DESCRIPTION (provided by applicant): Project Summary: Trematode flatworms of the genus Schistosoma are the causative agents of schistosomiasis. One potential physiological target for new anti-schistosoma drugs is the worm's system for excretion of wastes and xenobiotics. P-glycoprotein (Pgp), a member of the ATP-binding cassette superfamily of proteins, is an ATP-dependent efflux pump involved in transport of toxins and xenobiotics from cells. In vertebrates, Pgp is the product of the multi-drug-resistance 1 gene, which is amplified and over-expressed in tumor cells that show broad drug resistance. Pgp may also play a role in drug resistance in helminths. A schistosome Pgp cDNA (SMDR2) was sequenced several years ago, but has not been functionally characterized. The long-term goal of this proposal is to dissect the functional role and pharmacological sensitivities of SMDR2 and other schistosome drug transporters. We will adapt a calcein fluorescence assay to examine the substrate and inhibitor specificities of expressed SMDR2 and other transporters. We will also examine the effects of praziquantel, the current antischistosomal of choice, on expression of SMDR2, and whether praziquantel-resistant isolates have altered expression of this or other transporters. Finally, we will examine the effect on the parasite of genetic or pharmacological disruption of SMDR2. The specific aims of the project are to answer the following questions: 1. What are the biochemical properties and substrate specificities of SMDR2 and other schistosome drug transporters expressed in mammalian cells? 2. What is the tissue distribution and developmental profile of SMDR2 and other schistosome multi-drug transporters? 3. Does exposure to agents such as PZQ result in changes in SMDR2 expression or distribution? 4. Do isolates of worms with reduced susceptibility to PZQ show differences in expression levels of SMDR2 or other multidrug transporters? 5. What effects do genetic and pharmacological disruption of SMDR2 have on parasite survival, physiology and pharmacological sensitivities/relevance: Schistosomiasis is a major tropical disease caused by parasitic flatworms called schistosomes. Potential physiological targets for new drugs against schistosomiasis might be the transporters that remove wastes and toxins from schistosome cells. We propose to use several approaches to determine the properties of one such schistosome molecule, P-glycoprotein, which, in vertebrates, is also involved in resistance to a broad array of drugs.