The Role of Mucin-type O-glycosylation in Fitness and Transmission of Intestinal Symbiotic Bacteria In Vivo

背景和理论基础。人类的肠道是数以万亿计的各种不同类型细菌的家园。我们现在知道，这个庞大的微生物群落在宿主生理中扮演着许多角色，包括消化、能量获取和维生素生产。然而，我们不清楚宿主如何提供一个环境，让这些有益的细菌在肠道中茁壮成长。一个新出现的因素是肠道粘液，它由肠道衬里的细胞分泌，并与微生物区系混合。这种粘液主要由被称为“O-葡聚糖”的结构组成，这种结构由不同类型的糖分子以独特的构象连接在一起，呈现给微生物区系。尽管有这些知识，但我们仍然不清楚这些O-葡聚糖在促进微生物种群繁荣方面的重要性，这主要是因为缺乏有效的工具来在生命系统中研究它们。我们也不知道在O-葡聚糖如何影响微生物区系方面，男性和女性是否存在差异。这在我们对哺乳动物结肠生态系统和维持种群中有益细菌的理解方面留下了严重的差距。幸运的是，我们现在可以使用新的遗传和细菌工具，使我们能够操纵O-糖基化系统，以及可视化和跟踪哺乳动物肠道(小鼠)的特定细菌反应。 目标和方法。我的长期目标是确定分泌粘液的宿主糖基化程序如何影响哺乳动物的结肠生态系统，以促进与我们的微生物区系的互利互动。对于这项为期五年的发现基金，我有三个短期目标，重点是宿主O-葡聚糖如何有助于肠道微生物的生存。我的假设是，粘液上的O-葡聚糖对于在由于饮食和其他干预而改变的管腔环境中促进微生物区系的稳定性是必不可少的。利用我在遗传工具方面的专业知识在哺乳动物(小鼠)的结肠中制造各种O-葡聚糖缺陷，结合我的“记者”细菌，我将使用微生物学、显微镜和计算方法中的技术来测试不同的糖基化计划如何影响我的记者的定植能力、找到它们的利基并在男性和女性肠道中茁壮成长。 Impact和HQP。这些研究将通过解决微生物学和微生物群研究中的一个基本问题，提高加拿大在自然科学领域的国际研究影响力。具体地说，它将产生与以下方面相关的发现：对哺乳动物微生物区系感兴趣的微生物学家；试图了解O-葡聚糖如何影响微生物区系群落的糖生物学家；研究性生物学和基于性别的生物学的研究人员；以及希望了解肠道如何帮助支持微生物种群的普通公众。这一研究计划还将为加拿大HQP提供一个理想的培训场所，他们将在学术界和工业界的职位上具有竞争力。

BACKGROUND AND RATIONALE. The human gut is home to trillions of bacteria of many different types. We know now this vast microbial community plays many roles in host physiology, including digestion, energy acquisition, and vitamin production. However, we are not clear how the host provides an environment that allows such beneficial bacteria to thrive in the gut. One emerging factor is intestinal mucus, which is secreted by cells of the gut lining and intermixes with the microbiota. This mucus is mostly comprised of structures called “O-glycans”, which are made up of sugar molecules of different types joined together in unique conformations that are presented to the microbiota. Despite this knowledge, we still are unclear how important these O-glycans are in promoting a thriving microbial population, largely due to the lack of effective tools to study them in a living system. We also do not know whether differences in males and females exist in regards to how O-glycans impact the microbiota. This leaves a serious gap in our understanding of mammalian colon ecosystems and maintenance of beneficial bacteria in a population. Fortunately, we now have access to novel genetic and bacterial tools that allow us to manipulate the O-glycosylation system, as well as visualize and track specific bacterial responses, in a model mammalian gut (mouse). OBJECTIVES AND METHODS. My long-term objective is to determine how the host glycosylation program of the secreted mucus influences the mammalian colon ecosystem to promote mutually beneficial interactions with our microbiota. I have three short-term objectives for this five-year Discovery Grant, which focus on how host O-glycans contribute to microbial survival in the gut. My hypothesis is that the O-glycans on mucus are essential for promoting stability of the microbiota in the face of a changing luminal environment due to dietary and other interventions. Using my expertise with genetic tools to create various O-glycan deficiencies in the mammalian (mouse) colon, in combination with my “reporter” bacteria, I will use techniques in microbiology, microscopy, and computational approaches to test how different glycosylation programs impact the ability of my reporter to colonize, find their niche, and thrive in male and female intestines. IMPACT AND HQP. These studies will boost Canada's international research impact in the natural sciences by addressing a fundamental question in microbiology and microbiota research. Specifically, it will generate findings relevant to microbiologists interested in the mammalian microbiota; glycobiologists seeking to understand how O-glycans impact microbiota communities; researchers studying sex- and gender-based biology, and the general public who wish to understand how their intestines help support their microbial populations. This research program will additionally provide an ideal training ground for Canadian HQP who will be competitive for positions in academia and industry.