Mediator regulation of transporters in fluconazole resistant C. albicans mutants

描述(由申请人提供)：白色念珠菌是最常见的人类真菌病原体，也是医院获得性血液感染的主要原因。在美国，与系统性念珠菌病相关的死亡率约为40%，每年有超过10,000人死亡。唑类药物在控制这些感染方面取得了一些成功。然而，美国疾病控制中心最近发布的一份报告《2013年美国的抗生素耐药性威胁》优先将对唑耐药的白色念珠菌列为对美国人类健康的“严重”威胁。此外，在发展中国家患有口咽部念珠菌病的艾滋病毒/艾滋病患者中，唑类耐药性尤其高，这些患者无法获得高效的抗逆转录病毒治疗，导致高发病率和死亡率。了解唑(和其他抗真菌药物)耐药性的分子基础对于减少疾病负担至关重要。临床分离的耐唑白色念珠菌和其他真菌病原体经常包含锌簇转录因子功能突变的获得，导致多药外排泵转录增加。然而，人们对这些高度活跃的转录因子用于激活其靶标的机制知之甚少。介体是一种高度保守的共激活复合体，对大多数真核基因的转录调控是必需的。Mediator中的各个亚基可以是不同的，并调节特定生物体中的特定基因亚组。我们假设，锌簇转录因子功能突变的获得与介体的某些亚单位有特定的相互作用，从而促进 多药外排泵基因转录激活与抗真菌耐药性。这项探索性建议的目的是明确Mediator如何促进Tac1功能突变导致的氟康唑耐药性，Tac1是一种白色念珠菌锌簇转录因子，调节转运体Cdr1和Cdr2。此外，我们将比较不同Tac1功能突变体所使用的机制，以确定是否存在共同的相互作用，可以作为治疗靶点。初步证据表明，这种机制可能依赖于真菌特有的介体亚基，进一步支持了这种治疗方法的可行性。

DESCRIPTION (provided by applicant): C. albicans is the most prevalent human fungal pathogen and is a leading cause of hospital-acquired bloodstream infections. There is an approximately 40% mortality rate, and over 10,000 deaths per year in the U.S. associated with systemic candidiasis. Azole drugs have met with some success in controlling these infections. However, a recently released Center for Disease Control report 'Antibiotic resistance threats in the United States, 2013' prioritized azole resistant C. albicans as a 'serious' threat to human health in the U.S. In addition, azole resistance runs especially high in HIV/AIDS patients suffering from oropharyngeal candidiasis in the developing world that lack access to highly active antiretroviral therapy, resulting in high morbidity and mortality. Understanding the molecular basis of azole (and other anti-fungals) resistance is critical to reducing disease burden. Clinical isolates of azole resistant C. albicans, and other fungal pathogens, frequently contain gain of function mutations in zinc cluster transcription factors that result in increased transcription of multi-drug efflux pumps. Little, however, is known about the mechanism used by these hyperactive transcription factors to activate their targets. Mediator is a highly conserved co-activator complex that is necessary for transcriptional regulation of most eukaryotic genes. Individual subunits within Mediator can be divergent and regulate specific subsets of genes within particular organisms. We hypothesize that gain of function mutations in zinc cluster transcription factors confer specific interactions with certain subunits of Mediator, which promote transcriptional activation of multi-drug efflux pump genes and anti-fungal resistance. The objective of this exploratory proposal is to specifically determine how Mediator facilitates fluconazole resistance conferred by gain of function mutations in Tac1, a C. albicans zinc cluster transcription factor that regulates the transporters Cdr1 and Cdr2. Moreover, we will compare the mechanisms used by different Tac1 gain of function mutants in order to determine whether there is a common interaction that could be therapeutically targeted. Preliminary evidence suggests this mechanism could be dependent on Mediator subunits specific to fungi, further supporting the feasibility of such a therapeutic approach.