ANTIFUNGAL RESPONSE--MDR INDUCTION

真菌可能会以特定的方式对抗真菌化疗的压力，最终降低治疗的疗效。这种“抗真菌反应”类似于热休克反应，但在机制上不同。这个建议的重点是这样的抗真菌反应，称为MDR诱导，涉及快速的药物依赖性转录诱导的基因编码的转运蛋白参与多药耐药（MDR）。具体而言，将白色念珠菌、克鲁斯念珠菌或酿酒酵母暴露于某些药物（包括抗真菌唑类咪康唑和克霉唑、苯并咪唑阿苯达唑和磺胺嘧啶）15-20分钟诱导编码特异性MDR转运蛋白的mRNA增加3至> 10倍。最初的研究表明，MDR诱导是念珠菌属物种对苯并咪唑类的内在抗性以及诱导MDR的化合物（阿苯达唑和磺胺嘧啶）与作为MDR转运蛋白底物的化合物（唑类）之间的拮抗活性的最可能的解释。假设，MDR诱导也可能有助于表型适应唑类（反映在“拖尾效应”），不同的真菌不同唑类的敏感性，并获得抗真菌药物耐药性。本建议的具体目的是检查：（1）MDR诱导谱。新的抗真菌药物和抗感染药物通常用于免疫功能低下的患者将进行测试的C。白念珠菌多药耐药诱导和唑类药物的拮抗作用。MDR诱导和拮抗作用将在唑敏感和耐药菌株中进行比较，并在C。白色念珠菌酵母和菌丝形式。 将从光滑念珠菌、烟曲霉和新型隐球菌中扩增MDR基因片段，并将其用作这些真菌中MDR诱导研究的探针。 (2)诱导C.白色念珠菌 在酿酒酵母中的初步研究表明，在唑依赖性MDR诱导中有两类转录激活因子，PDR 1/PDR 3和YAP 1/YAP 2。 这些因子的念珠菌同源物将通过PCR或在S.啤酒。它们在MDR诱导中的作用将通过基因破坏来检查。

Fungi may respond to the stress of antifungal chemotherapy in specific ways that ultimately reduce the efficacy of the therapy. This "antifungal response" would be analogous to, but mechanistically distinct from, the heat shock response. The focus of this proposal is one such antifungal response, termed MDR induction, involving the rapid drug-dependent transcriptional induction of genes encoding transporters involved in multidrug resistance (MDR). Specifically, a 15-20 min exposure of Candida albicans, Candida krusei, or Saccharomyces cerevisiae to certain drugs (including the antifungal azoles miconazole and clotrimazole, the benzimidazole albendazole, and sulfadiazine) induced a 3 to > 10-fold increase in mRNAs encoding specific MDR transporters. initial studies indicate that MDR induction is the most likely explanation for the intrinsic resistance of Candida species to benzimidazoles and for the antagonistic activity between compounds that induce MDR (albendazole and sulfadiazine) and compounds that are substrates for the MDR transporters (azoles). Hypothetically, MDR induction could also contribute to phenotypic adaptation to azoles (reflected in the "trailing effect"), to the variable sensitivity of different fungi to different azoles, and to acquired antifungal drug resistance. The Specific Aims of this proposal are to examine the: (1) Spectrum of MDR induction. New antifungal agents and anti-infective agents commonly used in immunocompromised patients will be tested for C. albicans MDR induction and antagonism of azole activity. MDR induction and antagonism will be compared in azole-sensitive and resistant isolates, and in C. albicans yeast and hyphal forms. MDR gene fragments will be amplified from Candida glabrata, Aspergillus fumigatus, and Cryptococcus neoformans and used as probes for MDR induction studies in those fungi. (2) Transcriptional activators of MDR induction in C. albicans. Initial studies in Saccharomyces cerevisiae have implicated two classes of transcriptional activators in azole-dependent MDR induction, PDR1/PDR3 and YAP1/YAP2. Candida homologues of these factors will be identified by PCR or expression in S. cerevisiae. Their role in MDR induction will be examined by gene disruption.