Genetic and Evolutionary Basis of Fungal Drug Resistance

真菌耐药性的遗传和进化基础

• 批准号: 8260327
• 负责人: Zhenglong Gu
• 金额: $ 33.18万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8260327
• 关键词: Acquired Immunodeficiency Syndrome; Amphotericin B; Antibiotics; Antifungal Agents; Candida albicans; Candidate Disease Gene; Clinical; Comparative Genomic Analysis; Complex; Data; Diagnosis; Diploidy; Disease; Drug resistance; Environment; Ergosterol; Evolution; Fluconazole; Fungal Drug Resistance; Gene Expression Profiling; Genes; Genetic; Genome; Genotype; Goals; Growth; Haploidy; Herbicides; Homeostasis; Immunocompromised Host; Individual; Industrial fungicide; Laboratories; Lead; Libraries; Link; Local Anti-Infective Agents; Maps; Messenger RNA; Methodology; Methods; Modeling; Mutation; Mycoses; Nature; Other Genetics; Patients; Pesticides; Pharmaceutical Preparations; Phenotype; Population; Quantitative Trait Loci; Resistance; Saccharomyces cerevisiae; Staining method; Stains; Testing; Tissue Transplantation; Virulence Factors; Work; Yeasts; base; chemotherapy; coping; fungus; gene replacement; global health; improved; interest; paralogous gene; pathogen; pleiotropism; public health relevance; research study; small molecule; tool; trait; treatment strategy; yeast genetics

DESCRIPTION (provided by applicant): Fungal pathogens can be lethal, especially among immunocompromised populations, such as patients with AIDS, or recipients of tissue transplantation or chemotherapy. Virulence factors for fungal pathogens, such as pathogenic fungal drug resistance, often are quantitative traits. A goal of our laboratories is to map quantitative trait genes that underlie the resistance of pathogenic yeast strains to anti-fungal agents and to determine the evolution of this resistance. This work will improve diagnosis and treatment strategies and lead to a better understanding of the evolution of adaptive complex traits. The preliminary data for mapping sensitivity of the pathogenic strain (YJM789) to one antifungal drug (Fluconazole) using whole genome tiling array successfully identified a candidate gene (PDR5), and subsequent experiments were able to show that the mutation is solely responsible for YJM789-sensitivity to Fluconazole (a Mendelian trait). Surprisingly, the same mutation confers YJM789 drug resistance to another antifungal drug (Amphotericin B, AmB), which is a quantitative trait also determined by other genetic factors. The current results represent an interesting case of "antagonistic pleiotropy" (i.e., certain genes are functional in some conditions, but could be deleterious in others) and adaptive gene loss with clinical importance. In Aim 1, we will apply QTL mapping methods and several alternative yeast genetic tools to identify other genes responsible for AmB resistance in YJM789. Interactions among contributing genes will also be quantified. In Aim 2, we will analyze the individual functions of the QTL genes to provide a mechanistic explanation for AmB resistance. A specific focus will be on determining why deletion of PDR5, a contributing genetic factor we have already identified, increases AmB resistance in yeasts. We hypothesize that PDR5 and its paralogous genes are involved in ergosterol homeostasis, which will be tested in S. cerevisiae and in a pathogenic yeast species, Candida albicans. The function and evolution of other genes identified in Aim 1 will also be investigated. In Aim 3, we will identify additional QTLs that are linked to drug resistance. More specifically, we will phenotype our panel of haploid progeny under a library of different small molecule drugs. Genetic loci which are responsible for the unique growth phenotypes of YJM789 in these environments will be identified using methodologies developed in Aim 1. These data will be used to test the hypotheses that the same types of drugs have similar functional mechanisms on pathogenic yeast growth and that mutations on certain regions of the genome can enable pathogenic yeasts to cope with exogenous small molecules. PUBLIC HEALTH RELEVANCE: Drug resistance of pathogenic fungi is a global health threat, especially among immunocompromised populations such as patients with AIDS, or recipients of tissue transplantation or chemotherapy. In this proposal, the PIs and their laboratories plan to use QTL mapping method (by applying whole genome tiling array) to identify genes underlying antifungal drug resistance in pathogenic yeast and use drug resistance phenotype as a model to study the evolution of complex traits in nature. This work may improve diagnosis and treatment strategies for pathogenic fungal infection.

描述（由申请人提供）：真菌病原体可能是致命的，尤其是在免疫功能低下的人群中，例如艾滋病患者、组织移植或化疗的接受者。真菌病原体的毒力因子，例如致病真菌的耐药性，通常是数量性状。我们实验室的一个目标是绘制致病性酵母菌株对抗真菌药物抗性的数量性状基因图谱，并确定这种抗性的演变。这项工作将改进诊断和治疗策略，并更好地理解适应性复杂特征的进化。使用全基因组平铺阵列绘制致病菌株（YJM789）对一种抗真菌药物（氟康唑）敏感性的初步数据成功鉴定了候选基因（PDR5），随后的实验能够表明该突变是YJM789对氟康唑（孟德尔性状）敏感性的唯一原因。令人惊讶的是，相同的突变使 YJM789 对另一种抗真菌药物（两性霉素 B，AmB）产生耐药性，这是一个也由其他遗传因素决定的数量性状。目前的结果代表了“拮抗性多效性”（即某些基因在某些条件下有功能，但在其他条件下可能有害）和具有临床重要性的适应性基因丢失的有趣案例。在目标 1 中，我们将应用 QTL 作图方法和几种替代酵母遗传工具来识别 YJM789 中负责 AmB 抗性的其他基因。贡献基因之间的相互作用也将被量化。在目标 2 中，我们将分析 QTL 基因的个体功能，为 AmB 抗性提供机制解释。具体重点是确定为什么删除 PDR5（我们已经确定的一种遗传因素）会增加酵母中的 AmB 抗性。我们假设 PDR5 及其旁系同源基因参与麦角甾醇稳态，这将在酿酒酵母和致病性酵母菌白色念珠菌中进行测试。目标 1 中确定的其他基因的功能和进化也将得到研究。在目标 3 中，我们将鉴定与耐药性相关的其他 QTL。更具体地说，我们将在不同小分子药物库下对我们的单倍体后代进行表型分析。将使用目标 1 中开发的方法来鉴定在这些环境中导致 YJM789 独特生长表型的基因位点。这些数据将用于测试以下假设：相同类型的药物对病原酵母生长具有相似的功能机制，并且基因组某些区域的突变可以使病原酵母能够应对外源小分子。 公共卫生相关性：病原真菌的耐药性是一个全球性的健康威胁，特别是在艾滋病患者、组织移植或化疗接受者等免疫功能低下人群中。在该提案中，PI及其实验室计划使用QTL作图方法（通过应用全基因组平铺阵列）来识别病原酵母中抗真菌药物抗性的基因，并使用药物抗性表型作为模型来研究自然界复杂性状的进化。这项工作可能会改善病原真菌感染的诊断和治疗策略。