VERMONT COBRE: MOLECULAR MECHANISM OF ENTAMOEBA HISTOLYTICA PHAGOCYTOSIS

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。溶组织内阿米巴是一种肠道原虫寄生虫，可导致阿米巴痢疾和肝脓肿，估计每年感染5000万人。溶组织埃希氏菌对宿主细胞的杀伤和吞噬能力与寄生虫的毒力有关。事实上，宿主红细胞的吞噬作用是光学显微镜下区别于非致病性肠道内阿米巴Dixpar的唯一特征。用于临床诊断的特征。尽管细胞杀伤和吞噬在侵袭性阿米巴病中很重要，但人们对这些过程背后的分子机制知之甚少，它们在发病机制中的确切作用仍不清楚。我们的初步研究表明，溶组织埃希菌通过诱导细胞凋亡来杀死细胞，并比健康或坏死细胞更有效地摄取凋亡细胞。此外，我们还发现磷脂酰丝氨酸是阿米巴吞噬受体的潜在宿主细胞配基，富含丝氨酸的溶组埃希菌蛋白是潜在的受体。具体目标1将定义表面的性质和机制：挂在引发阿米巴摄取的凋亡宿主细胞上。这些研究不仅将告诉我们阿米巴吞噬受体的特异性，从而有助于识别它；确定在阿米巴细胞杀伤过程中导致配体暴露的宿主细胞事件，将是理解阿米巴细胞毒性的仍不清楚的机制的重要一步。目的2将使用生化和遗传方法来表征富含丝氨酸的蛋白和相关的富含天冬酰胺的蛋白的功能，并将提供关于这些蛋白在毒力中的作用的重要数据。Entomoeha研究界的一项重大创新将是开发RNA介导的干扰作为一种沉默这些蛋白质表达的方法。如果富含丝氨酸和/或天冬酰胺的蛋白在吞噬过程中的功能得到证实，这些实验将为今后体内研究吞噬作用在致病中的作用提供明确的吞噬缺陷。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Entamoeba histolytica, the enteric protozoan parasite that causes amebic dysentery and liver abscess, infects an estimated 50 million people annually. The ability of E. histolytica to kill and phagocytose host cells correlates with parasite virulence. In fact, phagocytosis of host erythrocytes is the only feature on light microscopy that distinguishes E. histolytica from the non-pathogenic intestinal ameba Entamoeba dixpar. a feature used for clinical diagnosis. Despite the importance of cell killing and phagocytosis in invasive amebiasis, very little is known about the molecular mechanisms underlying these processes and their precise contribution to pathogenesis remains unknown. Our preliminary studies have shown that E. histolytica kills cells by inducing apoptosis, and ingests apoptotic cells more efficiently than healthy or necrotic cells. In addition, we have identified phosphatidylserine as a potential host cell ligand for an amebic phagocytosis receptor and the serine-rich E. histolytica protein as a potential receptor. Specific aim 1 will define the nature and mechanism of surface :hanges on apoptotic host cells that trigger amebic ingestion. These studies will not only tell us the specificity of the amebic phagocytosis receptor, thereby helping to identify it; defining the host cell events that result in ligand exposure during amebic cell killing, will be an important step in understanding the still unclear mechanism of amebic cytotoxicity. Aim 2 will use both biochemical and genetic approaches to characterize the function of the serine-rich protein and of the related asparagine-rich proteins, and will provide important data on the role of these proteins in virulence. A major innovation for the Entumoeha research community will be development of RNA-mediated interference as a method to silence expression of these proteins. If the function of the serine-rich and/or the asparagine-rich proteins in phagocytosis is confirmed, furthermore, these experiments will provide E. histolytica with a defined phagocytosis defect for future in vivo studies of the contribution of phagocytosis to pathogenesis.