AIDS Related Oral Candidiasis: Drugs, Sterols, and Fungal Cells

描述（由申请方提供）：致病性酵母菌白色念珠菌（Ca）是免疫功能低下人群（包括AIDS患者）真菌感染的主要原因。通常用抗真菌药物治疗，最常见的是广泛用于艾滋病患者的唑类氟康唑。在这些患者中，唑类药物耐药的可能性很大。使用来自AIDS患者的口服耐药分离株，已经鉴定了耐药的主要机制，包括ERG 11（编码麦角固醇生物合成中的酶和唑类的靶点的基因）的改变和外排泵的表达增加。麦角甾醇是真菌细胞膜中的主要甾醇，其生物合成是唑类和许多其他抗真菌药物的靶标。真菌细胞与唑类化合物的相互作用是一个复杂的过程。代谢和环境的特定方面影响体外药物/细胞相互作用，并有可能在临床上发挥重要作用。这项研究的总体目标是了解真菌细胞如何对唑类反应。该提案调查进口，随后的调节固醇的UPC 2转录因子，和环境因素对细胞的药物反应的影响。该提案的具体目标是：1。研究氟康唑进入真菌细胞的特性。唑类药物的转运对细胞/药物的相互作用很重要，可能通过被动转运或主动转运来介导，以前没有研究过。2.分析UPC 2的转录调控。一旦在细胞内，唑类抑制Erg 11 p，改变固醇水平，并激活UPC 2转录因子，其调节固醇生物合成和摄取。将分析UPC 2基因的调控，以了解固醇代谢（包括摄取和生物合成）的变化如何与UPC 2的表达相关。3.描述特定环境因素对药物敏感性和细胞表面的影响。环境因素，包括pH值，氧气水平，氮源，和外源甾醇，将分析其对药物敏感性和细胞表面的影响，使用微生物，生物化学和基因表达的方法。4.表征临床分离株的甾醇代谢改变。已知的耐药机制并不适用于许多耐药菌株。这一目标将分析进口，UPC 2的调节，并响应环境因素，以确定可能的新的耐药机制，在这些菌株。了解唑类和真菌细胞之间的相互作用是一个具有临床意义的问题，有可能改善诊断，治疗和预防真菌感染和耐药性。

DESCRIPTION (provided by applicant): The pathogenic yeast Candida albicans (Ca) is a major cause of fungal infections in immune-compromised populations including AIDS patients. It is usually treated with antifungal drugs, most commonly the azole fluconazole which is used extensively in AIDS patients. In these patients, there is a significant probability that azole resistance will develop. Using oral resistant isolates from AIDS patients, major mechanisms of resistance have been identified including alterations in ERG11 (a gene encoding an enzyme in ergosterol biosynthesis and target of the azoles) and increased expression of efflux pumps. Ergosterol is the major sterol in the fungal plasma membrane; and its biosynthesis is the target for azoles and many other antifungals. The interaction of fungal cells with azoles is a complex process. Specific aspects of metabolism and the environment influence drug/cell interactions in vitro and have the potential to be important clinically. The Overall Goal of this research is to understand how a fungal cell responds to azoles. This proposal investigates import, subsequent regulation of sterols by the UPC2 transcription factor, and the influence of environmental factors on the cellular response to drugs. The Specific Aims of this proposal are: 1. To characterize fluconazole import into the fungal cell. Azole import is important to the cell/drug interaction; it may be mediated by passive or active transport; and it has not been studied previously. 2. To analyze the transcriptional regulation of UPC2. Once within the cell, azoles inhibit Erg 11 p, altering sterol levels, and activating the UPC2 transcription factor, which regulates sterol biosynthesis and uptake. Regulation of the UPC2 gene will be analyzed to understand how changes in sterol metabolism, including uptake and biosynthesis are correlated with expression of UPC2. 3. To characterize the effect of specific environmental factors on drug susceptibility and the cell surface. Environmental factors, including pH, oxygen levels, nitrogen sources, and exogenous sterols, will be analyzed for their effect on the drug susceptibility and the cell surface, using microbiological, biochemical and gene expression approaches. 4. To characterize clinical isolates for alterations in sterol metabolism. The known mechanisms of resistance do not apply to many resistant strains. This aim will assay import, UPC2 regulation, and response to environmental factors to identify possible new resistance mechanisms in these isolates. Understanding the interactions between azoles and fungal cells is a clinically significant issue, with the potential for improving diagnosis, treatment and prevention of fungal infections and resistance.