Calcium ATPases in Apicomplexan Parasites as Potential D

弓形虫是一种分布广泛的尖端复合体寄生虫，在美国是严重食源性疾病的常见原因，在免疫功能低下的人中会引起机会性疾病。弓形虫作为研究顶端复合体相关寄生虫生物学的模型系统具有许多优点，包括优秀的动物模型、强大的体外系统以及正向和反向遗传学。 因此，在这个系统中取得的进展也可能与其他重要的人类病原体有关，如隐孢子虫和疟疾的病原体(疟疾的病原体)。 Apicomplexan寄生虫依靠主动入侵进入宿主细胞，这一强制性步骤部分受微线虫粘附素的调节分泌控制。微线粒的分泌是一个钙依赖的过程和药物，扰乱钙信号的分泌，运动和侵袭。我们之前的研究表明，寄生虫中的钙水平经历了与运动性相关的振荡。这些钙振荡的破坏阻止了寄生虫的运动和细胞入侵。最近在疟疾方面的证据表明，中草药青蒿素(青蒿素)直接作用于钙调节系统的一个组成部分--肌浆内质网钙ATPase(SERCA)。至 进一步扩大这一发现，我们最近从弓形虫中克隆了SERCA基因。在目标1中，我们将研究SERCA在弓形虫中的表达和定位，并验证青蒿素与SERCA结合并抑制SERCA的钙泵作用，从而扰乱寄生虫生存的假说。在AIM2中，我们计划利用弓形虫现有的强大遗传系统来确定青蒿素的分子靶点，并绘制化合物的活性部位图。 这个项目解决了通过检查钙稳态的调节途径来更好地了解病原体的基本过程的需要。通过这些研究获得的知识可能会提高从药物上抑制关键的钙调节酶的能力，从而阻止这一重要寄生虫群体的运动和入侵。

Toxoplasma gondii is a widespread apicomplexan parasite that is a common cause of serious food borne illness in the USA and which causes opportunistic disease in immunocompromised individuals. Toxoplasma gondii offers a number of advantages as a model system for studying the biology of related apicomplexan parasites including excellent animals models, robust in vitro systems, and forward and reverse genetics. Consequently, advances made in this system may also be relevant to other important human pathogens such as Cryptosporidium and Plasmodium (the causative agent of malaria). Apicomplexan parasites rely on active invasion to enter host cells and this obligatory step is controlled in part by the regulated secretion of adhesins from micronemes. Microneme secretion is a calcium-dependent process and agents that disrupt calcium signaling block secretion, motility, and invasion. Our previous studies have shown that calcium levels in the parasite undergo oscillations that correlate with motility. Disruption of these calcium oscillations prevents motility and cell invasion by the parasite. Recent evidence in malaria suggests that the Chinese herbal medicine Qinghaosu (Artemisinin) acts directly on one component of the calcium regulatory system, the sarcoplasmic-endoplasmic reticulum calcium ATPase (SERCA). To expand further on this discovery, we have recently cloned the SERCA gene from T. gondii. In AIM 1, we will characterize the expression and localization of SERCA in T. gondii and test the hypothesis that artemisinin binds to and inhibits the calcium pumping action of SERCA, thus disrupting parasite survival. In AIM2, we plan to use to robust genetic systems available in T. gondii to confirm the molecular target of artemisinin and to map the active site of the compound. This project addresses the need for greater understanding of fundamental processes in pathogens through the examination of regulatory pathways in calcium homeostasis. Knowledge gained through these studies may improve the ability to pharmacologically inhibit key calcium regulatory enzymes and hence block motility and invasion by this important group of parasites.