Whaley Sarah G, Caudle Kelly E, Simonicova Lucia, Zhang Qing, Moye-Rowley W Scott, Rogers P David
Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, USA.
Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
mSphere. 2018 Feb 21;3(1). doi: 10.1128/mSphere.00466-17. eCollection 2018 Jan-Feb.
The high prevalence of fluconazole resistance among clinical isolates of has greatly hampered the utility of fluconazole for the treatment of invasive candidiasis. Fluconazole resistance in this yeast is almost exclusively due to activating mutations in the transcription factor Pdr1, which result in upregulation of the ABC transporter genes , , and and therefore increased fluconazole efflux. However, the regulation of Pdr1 is poorly understood. In order to identify genes that interact with the Pdr1 transcriptional pathway and influence the susceptibility of to fluconazole, we screened a collection of deletion mutants for those exhibiting increased resistance to fluconazole. Deletion of the gene coding for a protein homologous to the J protein Jjj1 resulted in decreased fluconazole susceptibility. We used the flipper method to generate independent deletion mutants for in an SDD clinical isolate. Expression of both and was increased in the absence of . In the absence of or , deletion of has only a modest effect on fluconazole susceptibility. Transcriptional profiling using transcriptome sequencing (RNA-seq) revealed upregulation of genes of the Pdr1 regulon in the absence of . Jjj1 appears to be a negative regulator of fluconazole resistance in and acts primarily through upregulation of the ABC transporter gene via activation of the Pdr1 transcriptional pathway. is the second most common species of recovered from patients with invasive candidiasis. The increasing number of infections due to , combined with its high rates of resistance to the commonly used, well-tolerated azole class of antifungal agents, has limited the use of this antifungal class. This has led to the preferential use of echinocandins as empirical treatment for serious infections. The primary mechanism of resistance found in clinical isolates is the presence of an activating mutation in the gene encoding the transcription factor Pdr1 that results in upregulation of one or more of the efflux pumps Cdr1, Pdh1, and Snq2. By developing a better understanding of this mechanism of resistance to the azoles, it will be possible to develop strategies for reclaiming the utility of the azole antifungals against this important fungal pathogen.
临床分离株中氟康唑耐药性的高流行率极大地阻碍了氟康唑在治疗侵袭性念珠菌病中的应用。该酵母中的氟康唑耐药性几乎完全是由于转录因子Pdr1中的激活突变，这导致ABC转运蛋白基因、和的上调，从而增加了氟康唑的外排。然而，对Pdr1的调控了解甚少。为了鉴定与Pdr1转录途径相互作用并影响对氟康唑敏感性的基因，我们筛选了一组缺失突变体，寻找那些对氟康唑耐药性增加的突变体。编码与J蛋白Jjj1同源的蛋白质的基因缺失导致氟康唑敏感性降低。我们使用flipper方法在SDD临床分离株中为生成独立的缺失突变体。在不存在的情况下，和的表达均增加。在不存在或的情况下，的缺失对氟康唑敏感性仅有适度影响。使用转录组测序（RNA-seq）进行转录谱分析显示，在不存在的情况下，Pdr1调控子的基因上调。Jjj1似乎是氟康唑耐药性的负调节因子，主要通过激活Pdr1转录途径上调ABC转运蛋白基因来发挥作用。是从侵袭性念珠菌病患者中分离出的第二常见的念珠菌物种。由于引起的感染数量不断增加，加上其对常用的、耐受性良好的唑类抗真菌药物的高耐药率，限制了这类抗真菌药物的使用。这导致优先使用棘白菌素作为严重感染的经验性治疗药物。临床分离株中发现的主要耐药机制是编码转录因子Pdr1的基因中存在激活突变，导致一个或多个外排泵Cdr1、Pdh1和Snq2上调。通过更好地理解这种对唑类药物的耐药机制，有可能制定策略来恢复唑类抗真菌药物对这种重要真菌病原体的效用。
