RNA interference in the fungal pathogen Candida albicans

真菌病原体白色念珠菌中的 RNA 干扰

• 批准号: 6704279
• 负责人: JANET F STAAB
• 金额: $ 17.13万
• 依托单位: SEATTLE BIOMEDICAL RESEARCH INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-12-01 至 2004-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6704279
• 关键词: Candida albicans; RNA interference; candidiasis; gene induction /repression; genetic regulation; heterochromatin; molecular cloning; open reading frames; virulence; virus genetics; virus morphology

DESCRIPTION (provided by applicant): Candida albicans is the most common etiologic agent of oropharyngeal candidiasis (OPC), an opportunistic infection in HIV v patients occurring in as many as 90% of AIDS patients at some point during the course of HIV disease. OPC is also seen at an appreciable rate in head and neck cancer patients due to impaired salivary function resulting from radiation therapy. A salient characteristic of C. albicans is the ability to grow in different morphological forms, from ovoid yeasts to filamentous hyphae. The expression of several virulence factors is intimately associated with morphology, and strains impaired in morphological transitions have reduced virulence in animal models. The molecular mechanism of how C. albicans coordinates expression of virulence genes with morphological forms is unclear. The recently described phenomenon of gene silencing termed post-transcriptional gene silencing (PTGS) triggered by double-stranded RNA (dsRNA) appears to be a conserved mechanism involved in resistance to viruses, protection of the genome from repetitive elements, developmental timing, and heterochromatin silencing. The PTGS effect is achieved by the degradation of mRNA termed RNA interference (RNAi). Genetic studies across many species have identified several homologous genes involved in RNAi, and in every organism where a PTGS function has been described, a member of the Argonaute protein family has been found. The finding of an ARGONAUTE gene homolog in C. albicans suggests that the fungus is capable of PTGS. This novel gene regulatory system may prove to be important in C. albicans for the regulation of virulence genes indirectly by affecting morphological transitions. The goals of this exploratory/developmental proposal are: (1) to uncover evidence in C. albicans of gene regulation by PTGS through RNAi; and (2) to determine the role of PTGS in control of virulence attributes through morphological transitions, and in maintenance of centromeric heterochromatic structure. The proposed initial studies will take genetic and molecular approaches to determine the capability of C. albicans to perform PTGS through analyses of RNAi constructs and gene knock out strains. Although the role of RNAi in the biology of C. albicans is unknown, the probability is high that novel gene regulatory mechanisms will be found that are common to other fungal pathogens.

描述(申请人提供)：白色念珠菌是口咽部念珠菌病(OPC)最常见的病原体，口咽念珠菌病是一种HIV v患者的机会性感染，在HIV病程中的某个时间点，高达90%的艾滋病患者会发生。由于放射治疗导致唾液功能受损，OPC在头颈部癌症患者中也有相当高的发生率。白色念珠菌的一个显著特征是能够以不同的形态生长，从卵形酵母到丝状菌丝。几种毒力因子的表达与形态密切相关，在动物模型中，形态转变中受损的菌株降低了毒力。白念珠菌如何协调毒力基因与形态表达的分子机制尚不清楚。最近报道的由双链RNA(DsRNA)触发的基因沉默现象被称为转录后基因沉默(PTGS)，它似乎是一种保守的机制，涉及到抵抗病毒、保护基因组免受重复元件的影响、发育时序和异染色质沉默。PTGS效应是通过被称为RNA干扰(RNAi)的mRNA降解实现的。许多物种的遗传学研究已经确定了与RNAi有关的几个同源基因，并且在每个描述了PTGS功能的生物中，都发现了ArgAerte蛋白家族的一个成员。在白色念珠菌中发现的Argavite基因同源基因表明，这种真菌具有PTGS的能力。这一新的基因调控系统可能被证明对白念珠菌通过影响形态转变间接调节毒力基因具有重要意义。这一探索性/发展性方案的目标是：(1)发现白色念珠菌中PTGS通过RNAi进行基因调控的证据；(2)确定PTGS在通过形态转变控制毒力属性和维持着丝粒异染色质结构中的作用。拟议的初步研究将采用遗传和分子方法，通过分析RNAi结构和基因敲除菌株来确定白色念珠菌执行PTGS的能力。尽管RNAi在白念珠菌生物学中的作用尚不清楚，但很有可能发现与其他真菌病原体相同的新的基因调控机制。