Mechanism of GPCR Signaling-mediated Fungal Cell Gigantism

GPCR信号介导真菌细胞巨型化的机制

• 批准号: 8765500
• 负责人: Chaoyang Xue
• 金额: $ 25.19万
• 依托单位: RBHS-NEW JERSEY MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8765500
• 关键词: AIDS/HIV problem; Accounting; Age; Alveolar Macrophages; Antifungal Agents; Brain; Cell Line; Cell Size; Cells; Cessation of life; Communicable Diseases; Communication; Cryptococcus; Cryptococcus neoformans; Cryptococcus neoformans infection; Cyclic AMP; Data; Development; Disease; Drug Targeting; Effectiveness; Endothelial Cells; Environment; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; GTP-Binding Proteins; Gigantism; Goals; Human; Immune; In Vitro; Infection; Integration Host Factors; Knowledge; Life; Ligand Binding; Ligands; Lung; Measures; Mediating; Medical; Meningitis; Mission; Modeling; Molecular; Morphogenesis; Mus; Mycoses; Neuraxis; New Agents; Orphan; Pathogenesis; Phenotype; Population; Production; Protein Subunits; Regulation; Research; Research Personnel; Resistance; Role; Saccharomyces; Signal Transduction; Signal Transduction Pathway; Staging; System; Testing; Titan; United States National Institutes of Health; Virulence Factors; XCR1 gene; Yeasts; base; design; fungus; human GPRC5C protein; immunoregulation; innovation; interest; meetings; novel; pathogen; public health relevance; receptor; receptor function; receptor internalization; trafficking

DESCRIPTION (provided by applicant): The proposal focuses on G protein-coupled receptor (GPCR) signaling in the fungal pathogen Cryptococcus neoformans, which infects the lung and often disseminates to the central nervous system to cause life- threatening meningitis. There is an urgent unmet medical need for developing new drug targets for better treatment of cryptococcal infection. To meet this need, it is critical to better understand the disease mechanisms by which the fungus senses host signals and adapts to the hostile host environment. One such adaptation strategy during infection is to dramatically enlarge yeast cell size, a novel cell morphogenesis called cell gigantism or "titan" cell formation. Fungal cell gigantism during lung infection has been recently recognized as a new virulence factor that is required for disease initiation and dissemination. Despite its importance in fungal pathogenesis, the host signals and fungal receptors for titan cell induction remain unknown. Studies from the applicant demonstrated that the Gpa1 (G protein ¿ subunit) G protein signal transduction pathway is involved in the production of titan cells. A novel G protein-coupled receptor (GPCR), Gpr5, has been identified as being essential for promoting titan cell formation. These new discoveries led to the central hypothesis that fungal cells sense host specific signals through the Gpr5 orphan receptor, which then activates Gpa1-mediated signaling to regulate fungal cell morphogenesis. The long-term goal is to understand the molecular basis of cryptococcal cell gigantism in order to provide the mechanistic details needed to develop new antifungal agents that interfere with GPCR function and inhibit titan cell formation during Cryptococcus infection. Guided by strong preliminary data, the hypothesis will be tested by two specific aims: 1) Define the function of Gpr5 in G-protein signaling activation and fungal titan cell regulation, and 2) Identify and characterize host signals required for Gpr5-mediated fungal cell gigantism. Under the first aim, strains having various levels of Gpr5 activity will be used to determine the role of Gpr5 in fungal titan cell production and pathogenesis in murine models, and to characterize how Gpr5 regulates the activation of Gpa1 as measured by cellular cAMP production. Under the second aim, a spent medium that can stimulate titan cell formation in vitro will be used to identify active compounds that are responsible for Gpr5-dependent cell gigantism. A Saccharomyces-based heterologous expression system will be used to analyze potential ligands for Gpr5 activation. The approach is innovative, because we have developed an in vitro system for titan cell formation that allows us to identify host factors responsible for cell gigantism. The proposed research is significant, because it aims to understand the molecular basis of the host-pathogen interaction during the development of virulence factors, which is critical for fungal pathogenesis. Ultimately, such knowledge will facilitate efforts to design new anti-fungal agents to perturb GPCR signaling in a therapeutically beneficial manner.

描述（由申请人提供）：该提案重点关注真菌病原体新型隐球菌中的 G 蛋白偶联受体 (GPCR) 信号传导，这种病原体感染肺部并经常传播到中枢神经系统，导致危及生命的脑膜炎。开发新药物靶点以更好地治疗隐球菌感染的未满足的医疗需求为了满足这一需求，更好地了解真菌感知宿主信号和疾病的机制至关重要。适应敌对宿主环境的一种适应策略是在感染过程中显着增大酵母细胞的大小，一种称为细胞巨人症或“泰坦”细胞形成的新型细胞形态发生最近被认为是一种新的毒力因子。尽管Gpa1（G蛋白）在真菌发病机制中很重要，但巨细胞诱导的宿主信号和真菌受体仍然未知。一种新型 G 蛋白偶联受体 (GPCR) Gpr5 已被确定为促进泰坦细胞形成所必需的，这些新发现导致了以下中心假设：真菌细胞通过 Gpr5 孤儿受体，然后激活 Gpa1 介导的信号传导以调节真菌细胞形态发生长期目标是了解隐球菌细胞巨人症的分子基础，以便提供开发干扰 GPCR 功能的新型抗真菌药物所需的机制细节。在强有力的初步数据的指导下，该假设将通过两个具体目标进行检验：1）定义 Gpr5 在 G 蛋白信号传导激活中的功能和真菌巨细胞调节，以及 2) 鉴定和表征 Gpr5 介导的真菌细胞巨人症所需的宿主信号 在第一个目标下，将使用具有不同水平 Gpr5 活性的菌株来确定 Gpr5 的作用。 Gpr5 在真菌泰坦细胞产生和小鼠模型发病机制中的作用，并通过细胞 cAMP 产生来表征 Gpr5 如何调节 Gpa1 的激活。在第二个目标下，将使用可以在体外刺激泰坦细胞形成的废培养基来鉴定。负责 Gpr5 依赖性细胞巨人症的活性化合物将使用基于酵母的异源表达系统来分析 Gpr5 激活的潜在配体。这项研究具有重要意义，因为它旨在了解毒力因子发展过程中宿主与病原体相互作用的分子基础，这对于巨细胞形成至关重要。最终，这些知识将有助于设计新的抗真菌药物，以有益于治疗的方式干扰 GPCR 信号传导。