SWITCHING IN THE ORAL COMMENSAL CANDIDA GLABRATA

口腔共生光滑念珠菌的转变

• 批准号: 6909106
• 负责人: DAVID R. SOLL
• 金额: $ 28.03万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6909106
• 关键词: Candida; Saccharomyces cerevisiae; clinical research; drug resistance; fungal genetics; gene deletion mutation; gene expression; genetic library; genetic regulatory element; genetic screening; genetic strain; human subject; laboratory mouse; microarray technology; nucleic acid hybridization; phenotype; restriction endonucleases; transcription factor

DESCRIPTION (provided by applicant): The emergence of Candida glabrata as a major commensal in the oral cavity of the elderly, and as the second most common yeast blood stream infection is a matter of dire concern. Because Candida glabrata is naturally drug-resistant, it puts at risk the elderly and immunocompromised, and causes chronic infections that an difficult to treat. The success of this pathogen, however, was puzzling since, unlike Candida albicans, it appeared to undergo neither high frequency phenotypic switching nor dimorphism, two developmental programs that provide mechanism for rapid adaptation in pathogenesis. We, therefore, searched for and discovered both developmental programs in C. glabrata. C. glabrata switches spontaneously, reversibly and at high frequency between four "core" phenotypes distinguishable on CuSO4-containing agar, white (Wh), light brown (LB), dark brown (DB) and very dark brown (vDB), and in addition switch to and from two "associated" switch phenotypes, unstable white (unWh) and irregular wrinkle (IWr). Core switching is unique in that all tested phenotypic characteristics and the expression of switching-regulated genes are graded in the hierarchies Wh less than LB less than DB less than vDB or Wh greater than LB greater than DB greater than vDB. Based upon the discovery of this uniquely graded switching system, and the recent suggestion of anatomical specialization of core switch phenotypes in the oral cavity and vagina of a chronic vaginitis patient, the following specific aims are proposed: 1) complete the characterization of switching and define the relationship of the associated switch phenotypes and the core switching system; 2) identify and characterize additional switching-regulated genes by differential hybridization screens and the use of S. cerevisiae cDNA-based arrays; 3) using REMI mutagenesis, identify and characterize genes involved in the switching process; 4) functionally characterize the cis-acting sequences and trans-acting factors involved in the graded expression; 5) discriminate between genes involved in the unWh and IWr phenotypes and genes involved in the pseudohypha and bud growth forms and 6) test whether switching affects drug susceptibility, other virulence traits and virulence in animal models, and confirm that the core switch phenotypes exhibit anatomical specialization.

描述(申请人提供)：光滑假丝酵母菌是老年人口腔中的主要共生菌，是第二常见的酵母菌血流感染，令人担忧。由于光滑念珠菌具有天然的抗药性，它使老年人和免疫功能受损的人处于危险之中，并导致难以治疗的慢性感染。然而，这种病原体的成功令人费解，因为与白色念珠菌不同，它似乎既没有经历高频表型转换，也没有经历二型性，这两种发育程序为发病机制提供了快速适应。因此，我们在光肩星天牛中搜索并发现了这两种发育程序。光滑毛壳在含CuSO4琼脂、白色(WH)、浅棕色(Lb)、深棕色(Db)和极深棕色(Vdb)上可区分的四种“核心”表型之间自发、可逆和高频切换，此外，还在两种“相关”切换表型之间切换，不稳定白色(UnWh)和不规则皱纹(IWR)。核心开关的独特之处在于，所有被测试的表型特征和开关调控基因的表达在WH小于Lb小于Db小于VDb或WH大于Lb大于Db的层级中分级。根据这一独特的分级开关系统的发现，以及最近关于慢性阴道炎患者口腔和阴道核心开关表型的解剖学特化的建议，提出了以下具体目标：1)完成开关的表征，并确定相关开关表型与核心开关系统的关系；2)通过差异杂交筛选和基于酿酒酵母基因阵列的使用，识别和表征其他开关调节基因；3)利用REMI突变，鉴定和表征参与开关过程的基因；4)从功能上表征分级表达中涉及的顺式作用序列和反式作用因子；5)区分与unWh和Iwr表型有关的基因，以及与假菌丝和芽生长有关的基因；6)在动物模型中检验转换是否影响药物敏感性、其他毒力性状和毒力，并证实核心开关表型具有解剖学上的专化性。