CAREER: Examining bacterial filamentation as a mechanism for cell-to-cell spreading in an animal host

该奖项全部或部分根据2021年美国救援计划法案（公法117-2）资助。细菌病原体对健康和农业构成持续威胁，对细菌如何在活体动物中传播的更深入了解可以为未来的治疗提供信息。小的透明线虫提供了一个机会，直接可视化细菌感染和传播的情况下，活的动物，允许发现新的机制，可能太难可视化在更复杂的动物，如哺乳动物。该提案使用野生分离的微观线虫及其相关的微生物群来揭示新的宿主-微生物相互作用。它的重点是解剖的机制，管理一个新的范例细胞内细菌传播宿主细胞之间，这是直接观察到的细菌感染的野生线虫。该项目的结果将作为一个技术路线图，用于确定这种细胞间传播的范例和控制它的遗传途径是否在其他细菌中保守，这可能为治疗细菌感染和控制环境细菌提供新的策略。早期阶段的本科生将为这一提议进行基于发现的研究，然后创建基于研究的STEM课程，在当地高中任教。这将在这些本科生中创造一个研究意识的循环，以帮助消除关于STEM研究可及性的持续心理障碍，特别是在第一代大学生和来自低收入地区的学生中。该项目的重点是一种新的细胞内细菌病原体，Bordetella atropi，在体内观察到其宿主线虫Oscheius tipulae中使用一种新的细胞间传播机制。肠细胞侵入后，B。atropi从球杆菌转化为丝状形态，以侵入多个相邻的上皮细胞。由B形成丝状体。atropi需要糖脂途径，这是一种保守的葡萄糖敏感途径，被细菌用来检测富含营养的环境。这个建议将调查的假设，B。atropi利用营养物传感来检测宿主细胞侵入、抑制分隔并触发分隔以扩散到邻近的肠细胞。具体目标是：（1）通过基因表达分析、代谢物分析和细胞生物学，剖析糖脂途径在控制致病中的作用;（2）了解B的感染过程。通过确定侧宿主膜的命运和识别促进寄生的宿主因子，来研究atropi，和（3）创建一个基于实验室的研讨会，使用野生线虫采样来发现在丰富条件下丝状的其他细菌和线虫的新的细胞内细菌病原体。最终的教育目标是让早期的本科生进行研究，然后在当地的高中教授他们的发现，使基于STEM的研究更容易为年轻学生所接受。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Bacterial pathogens pose a continuing threat to health and agriculture, and a deeper understanding of how bacteria spread in a live animal can inform future therapies. Small transparent nematodes offer an opportunity to directly visualize bacterial infection and dissemination in the context of a live animal, allowing for the discovery of novel mechanisms that may be too difficult to visualize in more complex animals like mammals. This proposal uses wild-isolated, microscopic nematodes and their associated microbiota to uncover novel host-microbe interactions. It focuses on dissecting the mechanisms governing a new paradigm for intracellular bacterial spreading between host cells, which was directly observed in a bacteria-infected wild nematode. The results from this project will serve as a technical roadmap for determining whether this paradigm for cell-cell spreading and the genetic pathway that controls it are conserved among other bacteria, which could provide novel strategies for treating bacterial infections and controlling environmental bacteria. Early-stage undergraduates will conduct discovery-based research for this proposal and then create research-based STEM curriculum to teach at local high schools. This will create a cycle of research awareness among these undergraduates to help eliminate persistent psychological barriers about the accessibility of STEM research, especially among first-generation college students and those from low income areas. This project focuses on a new intracellular bacterial pathogen, Bordetella atropi, that was observed in vivo to use a novel mechanism for cell-to-cell spreading in its host nematode Oscheius tipulae. After intestinal cell invasion, B. atropi converts from a coccobacillus to a filamentous morphology in order to invade multiple neighboring epithelial cells. Filamentation by B. atropi requires the glucolipid pathway, a conserved glucose-sensing pathway used by bacteria to detect a nutrient-rich environment. This proposal will investigate the hypothesis that B. atropi uses nutrient sensing to detect host cell invasion, inhibit septation, and trigger filamentation for spreading to neighboring intestinal cells. The specific aims are to (1) dissect the role of the glucolipid pathway in controlling filamentation through gene expression analysis, metabolite analysis, and cell biology; (2) understand the infection process of B. atropi by determining the fate of the lateral host membranes and identify host factors that promote filamentation, and (3) create a lab-based workshop that uses wild nematode sampling to discover other bacteria that filament in rich conditions and new intracellular bacterial pathogens of nematodes. This final education aim will have early-stage undergraduates conduct the research and then teach their discoveries at local high schools, making STEM-based research more accessible to young students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.