Mechanisms to restrain social cheating from quorum sensing in Pseudomonas aerugin

铜绿假单胞菌群体感应中抑制社会作弊的机制

• 批准号: 8665380
• 负责人: Ajai Dandekar
• 金额: $ 17.58万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8665380
• 关键词: Acute; Adenosine; Affect; Agar; Award; Bacteria; Behavior; Binding; Burn injury; Carbon; Caseins; Catabolism; Cause of Death; Cell Density; Cells; Chronic; Communities; Cooperative Behavior; Critical Care; Cystic Fibrosis; Diabetic wound; Disease; Ecology; Elements; Energy-Generating Resources; Ensure; Environment; Equilibrium; Evolution; Eye; Frequencies; Funding; Gene Expression; Genes; Genetic Transcription; Goals; Growth; Hereditary Disease; Human; Individual; Infection; Investigation; Keratitis; Knowledge; Laboratories; Life; Liquid substance; Lung; Lung diseases; Maintenance; Mediating; Medicine; Mentors; Metabolic; Metabolism; Microbiology; Morbidity - disease rate; Mutate; Mutation; Nutrient; Pathogenesis; Patients; Peptide Hydrolases; Physicians; Pneumonia; Police; Population; Process; Production; Proteins; Pseudomonas; Pseudomonas aeruginosa; Regulation; Relative (related person); Research; Resources; Sampling; Scientist; Signal Transduction; Structure; System; Testing; Therapeutic Intervention; Time; Universities; Variant; Ventilator; Virulence Factors; Washington; Work; Wound Infection; authority; career; cost; cystic fibrosis patients; density; deviant; insight; instructor; interest; medical schools; mortality; mutant; pathogen; pressure; prevent; public health relevance; quorum sensing; research study; signal processing; social; theories; transcription factor

DESCRIPTION (provided by applicant): This resubmission for a K08 physician-scientist career award is for support to transition to a career of independent investigation in the field of Pseudomonas aeruginosa quorum sensing. I recently transitioned from fellow to Acting Instructor of Pulmonary and Critical Care Medicine at the University of Washington (UW) and am conducting research in the lab of E. Peter Greenberg in the Department of Microbiology. I have the immediate goal of continuing my research into the evolution of quorum sensing that I initiated as a fellow. The Greenberg lab, Pulmonary Division, and the University of Washington all provide outstanding support to me. Dr. Greenberg is an authority on quorum sensing and bacterial pathogenesis, and I will continue to work in his group and its resources as I transition to an independent research career. The Pulmonary Division and the School of Medicine will ensure that, in addition to the funds provided, I have protected time for research and the institutional support necessary to achieve my long-term goal of independent investigation. This includes a mentoring committee composed of physician-scientists and clinicians, in addition to Dr. Greenberg, to ensure my continued progress during the term of this award. I propose the following research in this application: P. aeruginosa is a leading cause of morbidity and mortality in the genetic disease cystic fibrosis (CF). It also causes difficult-to-treat burn and diabetic wound infections, keratitis, and ventilator-associated pneumonia. P. aeruginosa engages in quorum sensing, a cell-density-dependent intercellular signaling mechanism that coordinates group behaviors including production of virulence factors and secreted proteases. P. aeruginosa quorum sensing is mediated in part by the transcription factor LasR. LasR regulates the transcription of hundreds of genes, many of which encode proteins that are involved in the production of secreted products. Such secreted products are "public goods" that are available to an entire community, not only the producing cell. As such, quorum sensing is susceptible to social cheating, wherein individuals mutate LasR so that they gain benefit from public goods without bearing a metabolic cost of production. In the CF lung, the frequency of LasR mutants can be high and these LasR mutants, which evolve de novo in the lung, have been implicated in the pathogenesis and progression of CF-related lung disease. In the laboratory, P. aeruginosa LasR mutants can evolve from the wildtype under conditions where a quorum-sensing-controlled secreted protease is required for growth. LasR mutants benefit from protease production by the wildtype and these LasR mutants achieve a population equilibrium with the wildtype. In my initial experiments, I showed that the emergence of LasR mutants can be prevented by the availability of adenosine, a "private good" and quorum-sensing controlled nutrient. This provides a mechanism for the population to police against deviant behavior. My proposal seeks to build on these initial experiments by answering the following questions: (1) What are the mechanisms by which the wildtype and LasR mutants achieve an equilibrium with one another? Because quorum sensing requires a sufficient density of cooperators, the emergence of LasR mutants should cause population collapse by reducing the number of cooperators below the threshold, but this does not occur; I seek reasons why. (2) Does spatial structure affect the emergence and frequency of LasR mutants? Infectious settings, including the CF lung, are likely to be structured and I propose to study the effects of spatial structure on the ability of LasR mutants to emerge in a population. Finally, (3), it has been proposed that the CF lung is a singular environment that supports the emergence of LasR mutants. I plan to test this hypothesis by collecting 100 or more environmental samples of P. aeruginosa and examining them for lasR mutations. The experiments described in this proposal will advance our knowledge of the evolution of cooperative behavior and give insight into the ecology of the CF lung.

描述（由申请人提供）：此重新提交的K 08医生科学家职业奖是为了支持过渡到铜绿假单胞菌群体感应领域的独立调查职业生涯。我最近从研究员转变为华盛顿大学（UW）的肺部和重症监护医学代理讲师，并在E。彼得·格林伯格在微生物学系。我的近期目标是继续我作为研究员开始的群体感应进化研究。格林伯格实验室、肺科和华盛顿大学都为我提供了出色的支持。格林伯格博士是群体感应和细菌发病机制方面的权威，在我过渡到独立研究生涯的过程中，我将继续在他的团队及其资源中工作。肺科和医学院将确保，除了提供的资金，我有保护的时间进行研究和必要的机构支持，以实现我的独立调查的长期目标。这包括一个由医生科学家和临床医生组成的指导委员会，除了格林伯格博士，以确保我在这个奖项的期限内继续进步。我在此申请中提出以下研究：铜绿假单胞菌是发病率和死亡率的主要原因 囊性纤维化（CF）的遗传性疾病。它还导致难以治疗的烧伤和糖尿病伤口感染、角膜炎和呼吸机相关性肺炎。铜绿假单胞菌参与群体感应，这是一种细胞密度依赖性细胞间信号传导机制，协调群体行为，包括毒力因子和分泌蛋白酶的产生。铜绿假单胞菌群体感应部分由转录因子LasR介导。LasR调节数百个基因的转录，其中许多基因编码参与分泌产物产生的蛋白质。这种分泌的产物是“公共产品”，不仅是生产细胞，而且是整个社区都可以获得的。因此，群体感应容易受到社会欺骗的影响，其中个体突变LasR，以便他们从公共产品中获益，而无需承担生产的代谢成本。在CF肺中，LasR突变体的频率可能很高，并且这些在肺中从头进化的LasR突变体与CF相关肺病的发病机制和进展有关。在实验室中，铜绿假单胞菌LasR突变体可以在生长所需的群体感应控制分泌蛋白酶的条件下从野生型进化而来。LasR突变体受益于野生型的蛋白酶生产，并且这些LasR突变体实现与野生型的群体平衡。在我最初的实验中，我证明了LasR突变体的出现可以通过腺苷的可用性来防止，腺苷是一种“私人物品”和群体感应控制营养素。这为民众提供了一种机制，以防止越轨行为。我的建议旨在通过回答以下问题来建立这些初步实验：（1）野生型和LasR突变体相互达到平衡的机制是什么？由于群体感应需要足够密度的合作者，LasR突变体的出现应该会导致人口崩溃的合作者的数量减少到阈值以下，但这不会发生;我寻求原因。(2)空间结构是否影响LasR突变体的出现和频率？感染环境，包括CF肺，很可能是结构化的，我建议研究空间结构对 LasR突变体在种群中出现的能力。最后，（3），已经提出CF肺是支持LasR突变体出现的单一环境。我计划通过收集100个或更多的铜绿假单胞菌环境样本并检查它们的lasR突变来验证这一假设。这个提议中描述的实验将推进我们对合作行为进化的认识 并深入了解CF肺的生态学。