AIDS Related Candidiasis: Dynamic Expression of Drug Resistant Genes

描述(由申请人提供)：在致病酵母白色念珠菌(Ca)中，临床分离株通常被分析其对生长反应梯度的生长反应。这些生长模式是细胞内基因表达模式的结果。在耐药菌株中，已知有四个基因结构性过表达，包括靶酶ERG11和三个外排泵CDR1、CDR2和MDR1。在易感钙中，当接触药物时，这些基因可以被转录诱导。然而，在耐药菌株中，这些基因对唑类的反应还没有被分析。这一假设是基于这样一种假设，即细胞对药物的反应可能是已知和未知耐药基因表达改变的结果，包括在没有药物时的结构性过度表达和在药物存在时的诱导基因表达。这项建议的总体目标是定义和表征一系列临床分离株对抗真菌药物的反应，并研究这些分离株除了结构性过度表达外，基因诱导的改变作为一种耐药机制。该提案的具体目标如下：目标1--确定真菌细胞对唑类化合物的反应范围。临床分离株将根据它们对唑类药物的生长反应进行分类。来自这些集群的8个代表性菌株将在随后的AIMS中进行基因表达分析。目的2-利用表达谱识别独特的基因诱导模式。来自AIM 1集群分析的代表性菌株将使用微阵列进行表达谱分析，以识别和表征对七种药物浓度梯度的基因诱导模式。目的3-表征独特的唑类诱导基因表达模式。定量逆转录聚合酶链式反应将被用来详细描述特定基因的诱导模式。目的4-鉴定和表征与表达模式改变相关的分子机制。临床分离株中的突变将通过测序进行鉴定，然后在实验室菌株中表征为重建。这项建议的重点是氮唑如何改变细胞的生长，以及氮唑如何改变基因诱导的模式，定义真菌对唑类药物的动态反应。这具有临床意义，因为患者的真菌永远不会简单地暴露在单一的高浓度药物中。这项研究的结果将对开发新的治疗方法和耐药的新诊断方法，以及重组治疗以最大限度地利用当前的抗真菌治疗具有重要意义。公共卫生相关性：致病酵母菌白色念珠菌是艾滋病患者最常见的机会性感染，发生在90%以上的患者中。以前对念珠菌对唑类药物的反应和耐药性的分析使用了敏感和耐药的临床分离株。这些分离株的基因表达分析侧重于在没有药物的情况下的构成基因表达，以及在单一药物浓度下的基因表达。目前的建议将集中在一系列选定的条件下的基因诱导，以了解真菌对唑类药物的动态反应。这具有临床意义，因为患者的真菌永远不会简单地暴露在一套确定的药物/真菌条件下。

DESCRIPTION (provided by applicant): In the pathogenic yeast Candida albicans (Ca), clinical isolates are commonly analyzed for their growth response to a gradient of growth responses. These growth patterns are the result of gene expression patterns within the cell. In resistant isolates, four genes are known to be constitutively overexpressed include the target enzyme ERG11, and three efflux pumps, CDR1, CDR2, and MDR1. In susceptible Ca, these genes can be transcriptionally induced when exposed to drugs. However, the response to azole by these genes has not been analyzed in resistant strains. This proposal is based on the hypothesis that the cell's response to drug may be the result of altered expression of known and unknown resistance genes that includes constitutive overexpression in the absence of drug and induced gene expression in the presence of drug. The overall goals of this proposal are to define and characterize the response to antifungal drug for a spectrum of clinical isolates, and to investigate those isolates for altered gene induction as a mechanism of resistance apart from constitutive overexpression. The Specific Aims of the proposal as follows: Aim 1 - To define the spectrum of responses of fungal cells to azoles. Clinical isolates will be clustered based on their growth responses to azole drugs. Eight representative isolates from these clusters will then be analyzed in subsequent aims for gene expression. Aim 2 - To identify unique gene induction patterns using expression profiling. Representative strains from the cluster analysis in Aim 1 will be expression profiled using microarrays to identify and characterize the gene induction patterns in response to a gradient of seven drug concentrations. Aim 3 - To characterize unique azole-induced gene expression patterns. QRT-PCR will be used to characterize the induction patterns of specific genes in detail. Aim 4 - To identify and characterize the molecular mechanisms associated with altered expression patterns. Mutations in the clinical isolates will be identified by sequencing and then characterized as reconstructions in laboratory strains. This proposal focuses on how azoles alter the cell's growth and how azoles alter the patterns of gene induction, defining a dynamic response of fungi to azole drugs. This has clinical significance, as fungi in a patient are never simply exposed to a single high drug concentration. The results from this study will have implications for the development of new therapies and new diagnostics of resistance, and for restructuring therapies to maximize current antifungal treatment. PUBLIC HEALTH RELEVANCE: The pathogenic yeast Candida albicans is the most common opportunistic infection in AIDS patients, occurring in over 90% of patients. Previous analyses of Candida's response to azole drugs and Candida drug resistance have used susceptible and resistance clinical isolates. Gene expression analysis in these isolates has focused on constitutive gene expression in the absence of drug, and on gene expression at a single drug concentration. The current proposal will focus on gene induction over a select spectrum of conditions to understand the dynamic response of fungi to azole drugs. This has clinical significance, as fungi in a patient are never simply exposed to one defined set of drug/fungus conditions.