Development of a Dictyostelium Discoideum Model for Genomic and Transcriptomic Analysis of Conserved Interactions with Enteric Pathogens

 描述(申请人提供)：哺乳动物的先天免疫细胞通过吞噬作用吸收并杀死入侵的细菌；然而，致病细菌菌株已经进化出逃避吞噬时的杀戮以逃避先天免疫防御的方法。土壤中的盘基鞭毛虫也利用吞噬作用吸收细菌，以达到营养目的。土壤中的细菌已经进化出躲避碟状芽孢杆菌捕食的机制，具有选择性优势，其中许多抗药性机制类似于细菌用来逃避哺乳动物天然免疫防御的机制。该项目验证了这样一种假设，即在这些抗性机制的发展过程中，针对盘状念珠菌捕食获得的选择优势可能有助于细菌对哺乳动物宿主的毒力因子的巧合进化。因此，研究逃避盘状螺旋体捕食的细菌机制可能会导致鉴定新的细菌毒力因子和细菌杀灭所需的宿主因子，一旦鉴定出来，就可以作为开发抗菌治疗的靶点。下一代测序技术的使用为盘状芽孢杆菌与其细菌猎物之间的相互作用的基因组和转录分析提供了强大的工具。此奖学金申请旨在支持Snyder博士在马里兰大学基因组科学研究所Rasko博士的实验室休假，以便将基因组和转录学方法纳入Snyder博士对盘状芽孢杆菌/细菌相互作用的研究，而Rasko博士在这方面拥有丰富的专业知识。该项目的具体目标是：1)分析已经进化出对盘状螺旋体捕食的抗性的细菌菌株的基因组；2)比较盘状螺旋体细胞和细菌猎物在细菌已经和没有进化出对盘状螺旋体吞噬细胞杀灭的抵抗力的情况下的转录反应。这些研究将使研究人员了解宿主-病原体相互作用的分子机制，并有助于深入了解细菌毒力因子的进化和维持以及逃避吞噬过程的机制。该项目的完成还将建立Snyder博士和Rasko博士的实验室之间的合作，并将为Snyder博士提供培训，以便她能够开发项目，使本科生和硕士研究生在她的研究实验室和道森大学以研究为基础的真实实验室课程中都能接触到基因组学研究。

 DESCRIPTION (provided by applicant): Mammalian innate immune cells take up and kill invading bacteria via phagocytosis; however, pathogenic bacterial strains have evolved means to evade killing upon phagocytic uptake to escape innate immune defense. The soil amoeba Dictyostelium discoideum also uses phagocytosis to take up bacteria for nutritive purposes. Bacteria in the soil that have evolved mechanisms to evade D. discoideum predation enjoy a selective advantage, and many of these resistance mechanisms are similar to those used by bacteria to evade mammalian innate immune defense. This project tests the hypothesis that the selective advantage gained against D. discoideum predation upon development of these resistance mechanisms may have contributed to coincidental evolution of bacterial virulence factors against mammalian hosts. Therefore, investigation of bacterial mechanisms used to evade D. discoideum predation could lead to identification of novel bacterial virulence factors and host factors required for bacterial killing, which once identified can be used as targets for development of anti-bacterial therapies. The use of next generation sequencing technology provides a powerful tool for genomic and transcriptomic analyses of the interactions between D. discoideum and its bacterial prey. This fellowship application seeks to support a sabbatical for Dr. Snyder in the laboratory of Dr. Rasko at the University of Maryland Institute for Genome Sciences in order to incorporate into Dr. Snyder's studies of D. discoideum/bacterial interactions genomic and transcriptomic approaches, for which Dr. Rasko has extensive expertise. The specific aims of the project are to 1) analyze the genomes of bacterial strains that have evolved resistance to D. discoideum predation and 2) compare the transcriptomic responses of D. discoideum cells and bacterial prey both in cases in which the bacteria have and have not evolved resistance to killing upon D. discoideum phagocytosis. These studies will inform the investigators on the molecular mechanisms underlying host-pathogen interactions and should lead to insight on the evolution and maintenance of bacterial virulence factors and mechanisms to evade the phagocytic process. Completion of this project will also establish collaborations between the laboratories of Dr. Snyder and Dr. Rasko and will provide Dr. Snyder training so that she can develop projects that will expose undergraduate and masters-level graduate students to genomics research both in her research laboratory and in authentic research-based laboratory courses at Towson University.