Role of lipid rafts and phosphoinositides in E. histolytica virulence

描述（由申请人提供）：溶组织内阿米巴是阿米巴痢疾和肝脓肿的病原体。它在全球发病率中排名第三，并被列为B类生物恐怖主义制剂。因此，了解这种病原体的生物学和开发创新的检测和治疗策略是当务之急。溶组织芽胞杆菌滋养体在感染过程中会遇到多种宿主细胞和大分子。据推测，这些细胞外成分在寄生虫中触发信号级联反应，导致毒力的变化。随着在溶组织芽胞杆菌中发现信号通路成分的速度，新的挑战是了解这些细胞中信号通路事件的时间和空间调节。在其他真核生物中，脂筏（富含胆固醇和鞘脂的质膜结构域）与肌动蛋白细胞骨架和磷酸肌苷（Pis）一起划分了质膜中的信号事件。最近发现，溶组织芽胞杆菌细胞具有筏状质膜结构域。筏体与一种重要的信号/粘附分子半乳糖/ n -乙酰半乳糖胺（Gal/GalNAc）凝集素的共定位表明，筏体也可能参与溶组织大肠杆菌的信号传导。在拟议的研究中，将探讨溶组织芽孢杆菌脂筏以及几种Pis的生物学作用。在第一个目标中，筏和肌动蛋白之间的关系，以及它们在毒力中的作用将被检查。在第二个目标中，脂筏、囊泡运输和肌动蛋白之间的联系将利用这些细胞成分解耦的突变体的遗传方法进行评估。最后，在第三个目标中，Pis在寄生虫毒力功能中的作用将被检查。这将通过检查PI 3-激酶和PTEN磷酸酶的功能来实现，酶在PI基础信号传导中具有互补作用。由于囊泡运输，肌动蛋白细胞骨架重排和信号可能调节毒性；这些研究将对了解溶组织芽胞杆菌的致病性有重要意义。公共卫生描述：溶组织内阿米巴是阿米巴痢疾和肝脓肿的病原体，在世界上因寄生虫病造成的死亡人数中排名第三。由于它也被列为生物恐怖主义制剂，因此了解其毒性是重中之重。拟议的研究将检查在寄生虫-宿主相互作用期间激活的信号通路。由于信号可能调节毒力，这些研究将有助于理解溶组织芽胞杆菌的生物学。

DESCRIPTION (provided by applicant): Entamoeba histolytica is the causative agent of amoebic dysentery and liver abscess. It ranks third as a worldwide cause of morbidity and has been classified as a Category B bioterrorism agent. Therefore, there is elevated priority to understand the biology of and develop innovative detection and therapeutic strategies for this pathogen. E. histolytica trophozoites will encounter a variety of host cells and macromolecules during infection. It is postulated that these extracellular components trigger signaling cascades in the parasite that lead to changes in virulence. With the rate at which the components of signaling pathways are being discovered in E. histolytica, the new challenge is to understand the temporal and spatial regulation of signaling events in these cells. In other eukaryotes, lipid rafts (cholesterol- and sphingolipid-rich plasma membrane domains), along with the actin cytoskeleton, and phosphoinositides (Pis), compartmentalize signaling events in the plasma membrane. Recently, E. histolytica cells were shown to possess raft-like plasma membrane domains. The co-localization of rafts with an important signaling/adhesion molecule, the galactose/N-acetylgalactosamine (Gal/GalNAc) lectin, suggests that rafts may also participate in signaling in E. histolytica. In the proposed studies, the biological role of E. histolytica lipid rafts, as well as of several Pis, will be explored. In the first Aim, the relationship between rafts and actin, and their role in virulence will be examined. In the second Aim, the connection between lipid rafts, vesicle trafficking, and actin will be assessed utilizing genetic approaches with mutants in which these cellular components are uncoupled. Finally, in the third Aim, the role of Pis in parasite virulence functions will be examined. This will be achieved by examining the function of PI 3-kinase and PTEN phosphatase, enzymes with complimentary roles in Pi- based signaling. Since vesicle trafficking, actin cytoskeletal rearrangements and signaling likely regulate virulence; these studies will contribute significantly to understanding the pathogenicity of E. histolytica. Public Health Description: Entamoeba histolytica is the causitive agent of amoebic dysentery and liver abscess and ranks third in the world for deaths due to parasitic disease. Since it is also classified as a bioterrorism agent, there is elevated priority to understand its virulence. The proposed studies will examine signaling pathways that are activated during parasite-host interaction. Since signaling likely regulates virulence, these studies will contribute significantly to understanding the biology of E. histolytica.