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Biermann AR, Hogan DA. Transcriptional Response of Candida auris to the Mrr1 Inducers Methylglyoxal and Benomyl. mSphere 2022; 7:e0012422. [PMID: 35473297 PMCID: PMC9241502 DOI: 10.1128/msphere.00124-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 03/18/2022] [Indexed: 11/20/2022] Open
Abstract
Candida auris is an urgent threat to human health due to its rapid spread in health care settings and its repeated development of multidrug resistance. Diseases that increase risk for C. auris infection, such as diabetes, kidney failure, or immunocompromising conditions, are associated with elevated levels of methylglyoxal (MG), a reactive dicarbonyl compound derived from several metabolic processes. In other Candida species, expression of MG reductase enzymes that catabolize and detoxify MG are controlled by Mrr1, a multidrug resistance-associated transcription factor, and MG induces Mrr1 activity. Here, we used transcriptomics and genetic assays to determine that C. auris MRR1a contributes to MG resistance, and that the main Mrr1a targets are an MG reductase and MDR1, which encodes a drug efflux protein. The C. auris Mrr1a regulon is smaller than Mrr1 regulons described in other species. In addition to MG, benomyl (BEN), a known Mrr1 stimulus, induces C. auris Mrr1 activity, and characterization of the MRR1a-dependent and -independent transcriptional responses revealed substantial overlap in genes that were differentially expressed in response to each compound. Additionally, we found that an MRR1 allele specific to one C. auris phylogenetic clade, clade III, encodes a hyperactive Mrr1 variant, and this activity correlated with higher MG resistance. C. auris MRR1a alleles were functional in Candida lusitaniae and were inducible by BEN, but not by MG, suggesting that the two Mrr1 inducers act via different mechanisms. Together, the data presented in this work contribute to the understanding of Mrr1 activity and MG resistance in C. auris. IMPORTANCE Candida auris is a fungal pathogen that has spread since its identification in 2009 and is of concern due to its high incidence of resistance against multiple classes of antifungal drugs. In other Candida species, the transcription factor Mrr1 plays a major role in resistance against azole antifungals and other toxins. More recently, Mrr1 has been recognized to contribute to resistance to methylglyoxal (MG), a toxic metabolic product that is often elevated in different disease states. MG can activate Mrr1 and its induction of Mdr1 which can protect against diverse challenges. The significance of this work lies in showing that MG is also an inducer of Mrr1 in C. auris, and that one of the major pathogenic C. auris lineages has an activating Mrr1 mutation that confers protection against MG.
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Affiliation(s)
- Amy R. Biermann
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A. Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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2
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Wang ZQ, Meng FZ, Yin LF, Yin WX, Lv L, Yang XL, Chang XQ, Zhang S, Luo CX. Transcriptomic Analysis of Resistant and Wild-Type Isolates Revealed Fludioxonil as a Candidate for Controlling the Emerging Isoprothiolane Resistant Populations of Magnaporthe oryzae. Front Microbiol 2022; 13:874497. [PMID: 35464942 PMCID: PMC9024399 DOI: 10.3389/fmicb.2022.874497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/23/2022] [Indexed: 11/22/2022] Open
Abstract
The point mutation R343W in MoIRR, a putative Zn2Cys6 transcription factor, introduces isoprothiolane (IPT) resistance in Magnaporthe oryzae. However, the function of MoIRR has not been characterized. In this study, the function of MoIRR was investigated by subcellular localization observation, transcriptional autoactivation test, and transcriptomic analysis. As expected, GFP-tagged MoIRR was translocated in the nucleus, and its C-terminal could autonomously activate the expression of reporter genes HIS3 and α-galactosidase in absence of any prey proteins in Y2HGold, suggesting that MoIRR was a typical transcription factor. Transcriptomic analysis was then performed for resistant mutant 1a_mut (R343W), knockout transformant ΔMoIRR-1, and their parental wild-type isolate H08-1a. Upregulated genes in both 1a_mut and ΔMoIRR-1 were involved in fungicide resistance-related KEGG pathways, including the glycerophospholipid metabolism and Hog1 MAPK pathways. All MoIRR deficiency-related IPT-resistant strains exhibited increased susceptibility to fludioxonil (FLU) that was due to the upregulation of Hog1 MAPK pathway genes. The results indicated a correlation between FLU susceptibility and MoIRR deficiency-related IPT resistance in M. oryzae. Thus, using a mixture of IPT and FLU could be a strategy to manage the IPT-resistant populations of M. oryzae in rice fields.
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Affiliation(s)
- Zuo-Qian Wang
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, China
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Wuhan, China
| | - Fan-Zhu Meng
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Liang-Fen Yin
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Wei-Xiao Yin
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Liang Lv
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, China
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Wuhan, China
| | - Xiao-Lin Yang
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, China
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Wuhan, China
| | - Xiang-Qian Chang
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, China
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Wuhan, China
| | - Shu Zhang
- Institute of Plant Protection and Soil Science, Hubei Academy of Agricultural Sciences, Wuhan, China
- Key Laboratory of Integrated Pest Management on Crops in Central China, Ministry of Agriculture, Wuhan, China
- *Correspondence: Shu Zhang,
| | - Chao-Xi Luo
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring and Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
- Chao-Xi Luo,
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Participation of the ABC Transporter CDR1 in Azole Resistance of Candida lusitaniae. J Fungi (Basel) 2021; 7:jof7090760. [PMID: 34575798 PMCID: PMC8467326 DOI: 10.3390/jof7090760] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 11/16/2022] Open
Abstract
Candida lusitaniae is an opportunistic pathogen in humans that causes infrequent but difficult-to-treat diseases. Antifungal drugs are used in the clinic to treat C. lusitaniae infections, however, this fungus can rapidly acquire antifungal resistance to all known antifungal drugs (multidrug resistance). C. lusitaniae acquires azole resistance by gain-of-function (GOF) mutations in the transcriptional regulator MRR1. MRR1 controls the expression of a major facilitator transporter (MFS7) that is important for fluconazole resistance. Here, we addressed the role of the ATP Binding Cassette (ABC) transporter CDR1 as additional mediator of azole resistance in C. lusitaniae. CDR1 expression in isolates with GOF MRR1 mutations was higher compared to wild types, which suggests that CDR1 is an additional (direct or indirect) target of MRR1. CDR1 deletion in the azole-resistant isolate P3 (V688G GOF) revealed that MICs of long-tailed azoles, itraconazole and posaconazole, were decreased compared to P3, which is consistent with the role of this ABC transporter in the efflux of these azoles. Fluconazole MIC was only decreased when CDR1 was deleted in the background of an mfs7Δ mutant from P3, which underpins the dominant role of MFS7 in the resistance of the short-tailed azole fluconazole. With R6G efflux readout as Cdr1 efflux capacity, our data showed that R6G efflux was increased in P3 compared to an azole-susceptible wild type parent, and diminished to background levels in mutant strains lacking CDR1. Milbemycin oxim A3, a known inhibitor of fungal ABC transporters, mimicked efflux phenotypes of cdr1Δ mutants. We therefore provided evidence that CDR1 is an additional mediator of azole resistance in C. lusitaniae, and that CDR1 regulation is dependent on MRR1 and associated GOF mutations.
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Nishimoto AT, Sharma C, Rogers PD. Molecular and genetic basis of azole antifungal resistance in the opportunistic pathogenic fungus Candida albicans. J Antimicrob Chemother 2021; 75:257-270. [PMID: 31603213 DOI: 10.1093/jac/dkz400] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Candida albicans is an opportunistic yeast and the major human fungal pathogen in the USA, as well as in many other regions of the world. Infections with C. albicans can range from superficial mucosal and dermatological infections to life-threatening infections of the bloodstream and vital organs. The azole antifungals remain an important mainstay treatment of candidiasis and therefore the investigation and understanding of the evolution, frequency and mechanisms of azole resistance are vital to improving treatment strategies against this organism. Here the organism C. albicans and the genetic changes and molecular bases underlying the currently known resistance mechanisms to the azole antifungal class are reviewed, including up-regulated expression of efflux pumps, changes in the expression and amino acid composition of the azole target Erg11 and alterations to the organism's typical sterol biosynthesis pathways. Additionally, we update what is known about activating mutations in the zinc cluster transcription factor (ZCF) genes regulating many of these resistance mechanisms and review azole import as a potential contributor to azole resistance. Lastly, investigations of azole tolerance in C. albicans and its implicated clinical significance are reviewed.
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Affiliation(s)
- Andrew T Nishimoto
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Cheshta Sharma
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - P David Rogers
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
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Demers EG, Stajich JE, Ashare A, Occhipinti P, Hogan DA. Balancing Positive and Negative Selection: In Vivo Evolution of Candida lusitaniae MRR1. mBio 2021; 12:e03328-20. [PMID: 33785623 PMCID: PMC8092287 DOI: 10.1128/mbio.03328-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
The evolution of pathogens in response to selective pressures present during chronic infections can influence their persistence and virulence and the outcomes of antimicrobial therapy. Because subpopulations within an infection can be spatially separated and the host environment can fluctuate, an appreciation of the pathways under selection may be most easily revealed through the analysis of numerous isolates from single infections. Here, we continued our analysis of a set of clonally derived Clavispora (Candida) lusitaniae isolates from a single chronic lung infection with a striking enrichment in the number of alleles of MRR1 Genetic and genomic analyses found evidence for repeated acquisition of gain-of-function mutations that conferred constitutive Mrr1 activity. In the same population, there were multiple alleles with both gain-of-function mutations and secondary suppressor mutations that either attenuated or abolished the constitutive activity, suggesting the presence of counteracting selective pressures. Our studies demonstrated trade-offs between high Mrr1 activity, which confers resistance to the antifungal fluconazole, host factors, and bacterial products through its regulation of MDR1, and resistance to hydrogen peroxide, a reactive oxygen species produced in the neutrophilic environment associated with this infection. This inverse correlation between high Mrr1 activity and hydrogen peroxide resistance was observed in multiple Candida species and in serially collected populations from this individual over 3 years. These data lead us to propose that dynamic or variable selective pressures can be reflected in population genomics and that these dynamics can complicate the drug resistance profile of the population.IMPORTANCE Understanding microbial evolution within patients is critical for managing chronic infections and understanding host-pathogen interactions. Here, our analysis of multiple MRR1 alleles in isolates from a single Clavispora (Candida) lusitaniae infection revealed the selection for both high and low Mrr1 activity. Our studies reveal trade-offs between high Mrr1 activity, which confers resistance to the commonly used antifungal fluconazole, host antimicrobial peptides, and bacterial products, and resistance to hydrogen peroxide. This work suggests that spatial or temporal differences within chronic infections can support a large amount of dynamic and parallel evolution and that Mrr1 activity is under both positive and negative selective pressure to balance different traits that are important for microbial survival.
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Affiliation(s)
- Elora G Demers
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Jason E Stajich
- Department of Microbiology & Plant Pathology and Institute for Integrative Genome Biology, University of California-Riverside, Riverside, California, USA
| | - Alix Ashare
- Dartmouth-Hitchcock Medical Center, Section of Pulmonary and Critical Care Medicine, Lebanon, New Hampshire, USA
| | - Patricia Occhipinti
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Deborah A Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
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Wang K, Lin Z, Zhang H, Zhang X, Zheng X, Zhao L, Yang Q, Ahima J, Boateng NAS. Investigating proteome and transcriptome response of Cryptococcus podzolicus Y3 to citrinin and the mechanisms involved in its degradation. Food Chem 2019; 283:345-352. [PMID: 30722882 DOI: 10.1016/j.foodchem.2019.01.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/16/2018] [Accepted: 01/13/2019] [Indexed: 11/28/2022]
Abstract
Citrinin (CIT) contamination has been reported in agricultural foods and is known to be nephrotoxic to human and animals. In the present study, the proteomes and transcriptomes of C. podzolicus Y3 treated with or without 10 μg/mL CIT were compared by two-dimensional electrophoresis (2-DE) and RNA sequencing, respectively. The proteomics results showed that there were 23 differentially expressed proteins (DEPs), 8 DEPs were up-regulated and 15 DEPs were significantly down-regulated. Transcriptomic analysis showed that 1208 genes were differentially expressed, 551 (43.05%) DEGs were up regulated and 657 (56.95%) were down-regulated. These results showed that the CIT treatment caused DNA damage, oxidative stress and cell apoptosis in C. podzolicus Y3. CIT treatment also activated the defense response (DNA repair and drug resistance biological process, antioxidative activity and TCA cycle) as well as drug metabolism (synthesize the CIT-degrading enzymes) in yeast cells to respond to CIT stress and degrade CIT.
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Affiliation(s)
- Kaili Wang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Zhen Lin
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Hongyin Zhang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China.
| | - Xiaoyun Zhang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Xiangfeng Zheng
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Lina Zhao
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Qiya Yang
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Joseph Ahima
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
| | - Nana Adwoa Serwah Boateng
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, People's Republic of China
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Wang ZQ, Meng FZ, Zhang MM, Yin LF, Yin WX, Lin Y, Hsiang T, Peng YL, Wang ZH, Luo CX. A Putative Zn 2Cys 6 Transcription Factor Is Associated With Isoprothiolane Resistance in Magnaporthe oryzae. Front Microbiol 2018; 9:2608. [PMID: 30429837 PMCID: PMC6220061 DOI: 10.3389/fmicb.2018.02608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 10/12/2018] [Indexed: 12/18/2022] Open
Abstract
Isoprothiolane (IPT), a systemic fungicide, has been applied to control rice blast since the 1970s. Although resistance to IPT has been observed, the mechanism of resistance still has not been fully elucidated. In this study, nucleotide polymorphisms were detected between two IPT-resistant mutants generated in the lab, and their parental wild type isolates using a whole-genome sequencing approach. In the genomes of the two resistant mutants, single point mutations were identified in a gene encoding a Zn2Cys6 transcription factor-like protein. Notably, either knocking out the gene or replacing the wild type allele with the mutant allele (R343W) in a wild type isolate resulted in resistance to IPT, indicating that the gene is associated with IPT resistance, and thus was designated as MoIRR (Magnaporthe oryzae isoprothiolane resistance related). Along with point mutations R343W in mutant 1a_mut, and R345C in 1c_mut, a 16 bp insertion in 6c_mut was also located in the Fungal_TF_MHR domain of MoIRR, revealing that this domain may be the core element for IPT resistance. In addition, IPT-resistant mutants and transformants showed cross-resistance with iprobenfos (IBP), which was consistent with previous observations. These results indicated that MoIRR is strongly connected to resistance to choline biosynthesis inhibitor (CBI), and further work should focus on investigating downstream effects of MoIRR.
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Affiliation(s)
- Zuo-Qian Wang
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Fan-Zhu Meng
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ming-Ming Zhang
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Liang-Fen Yin
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Wei-Xiao Yin
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Yang Lin
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
| | - Tom Hsiang
- School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
| | - You-Liang Peng
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
| | - Zong-Hua Wang
- College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chao-Xi Luo
- Department of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
- The Key Lab of Crop Disease Monitoring & Safety Control in Hubei Province, Huazhong Agricultural University, Wuhan, China
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Ksiezopolska E, Gabaldón T. Evolutionary Emergence of Drug Resistance in Candida Opportunistic Pathogens. Genes (Basel) 2018; 9:genes9090461. [PMID: 30235884 PMCID: PMC6162425 DOI: 10.3390/genes9090461] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 01/08/2023] Open
Abstract
Fungal infections, such as candidiasis caused by Candida, pose a problem of growing medical concern. In developed countries, the incidence of Candida infections is increasing due to the higher survival of susceptible populations, such as immunocompromised patients or the elderly. Existing treatment options are limited to few antifungal drug families with efficacies that vary depending on the infecting species. In this context, the emergence and spread of resistant Candida isolates are being increasingly reported. Understanding how resistance can evolve within naturally susceptible species is key to developing novel, more effective treatment strategies. However, in contrast to the situation of antibiotic resistance in bacteria, few studies have focused on the evolutionary mechanisms leading to drug resistance in fungal species. In this review, we will survey and discuss current knowledge on the genetic bases of resistance to antifungal drugs in Candida opportunistic pathogens. We will do so from an evolutionary genomics perspective, focusing on the possible evolutionary paths that may lead to the emergence and selection of the resistant phenotype. Finally, we will discuss the potential of future studies enabled by current developments in sequencing technologies, in vitro evolution approaches, and the analysis of serial clinical isolates.
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Affiliation(s)
- Ewa Ksiezopolska
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain.
- Universitat Pompeu Fabra (UPF), 08003 Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain.
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Feng W, Yang J, Yang L, Li Q, Zhu X, Xi Z, Qiao Z, Cen W. Research of Mrr1, Cap1 and MDR1 in Candida albicans resistant to azole medications. Exp Ther Med 2017; 15:1217-1224. [PMID: 29434708 PMCID: PMC5774345 DOI: 10.3892/etm.2017.5518] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 06/22/2017] [Indexed: 01/16/2023] Open
Abstract
The aim of the present study was to investigate the association between Mrr1, adenylyl cyclase-associated protein 1 (Cap1) and multi-drug resistance gene 1 (MDR1), and to assess the mutations in Mrr1 and Cap1 in azole-resistant Candida albicans strains. The study isolated 68 C. albicans strains from patients with vulvovaginal candidiasis. Drug susceptibility testing was conducted to characterize the resistance profile of these strains to fluconazole, itraconazole and voriconazole. Polymerase chain reaction (PCR) amplification was performed for Cap1 and Mrr1, and the PCR products were sequenced to identify any mutations. Reverse transcription-quantitative PCR was performed to measure Cap1, Mrr1 and MDR1 mRNA in C. albicans strains. The results of the present study indicated S381N, P311S and A390T missense mutations in Cap1 and T917M, T923I, N937K, E1020Q, F1032L and S1037L missense mutations in Mrr1 in azole-resistant C. albicans strains. Fluconazole-resistant strains had significantly elevated Cap1 and MDR1 mRNA levels compared with fluconazole-sensitive strains (P<0.01). The mRNA levels of Cap1, Mrr1 and MDR1 were significantly increased in the strains resistant to all three of fluconazole, itraconazole and voriconazole compared with strains sensitive to the three agents (P<0.001, P=0.037 and P<0.001, respectively). Cap1 expression was positively correlated with MDR1 expression in fluconazole-resistant strains (P<0.05). No significant correlation was observed between Cap1, Mrr1 and MDR1 in the strains resistant to fluconazole, itraconazole or voriconazole. The results of the present study suggested that fluconazole resistance may involve MDR1 overexpression mediated by Cap1 overexpression. Cross-resistance between fluconazole, itraconazole and voriconazole may be associated with mutations in Cap1 and Mrr1, rather than their overexpression. In addition, the present study also revealed two novel mutations in Mrr1; T917M and T923I. These findings may provide a basis for elucidating the molecular mechanisms of and improving therapeutic treatments to tackle azole resistance.
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Affiliation(s)
- Wenli Feng
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Jing Yang
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Lu Yang
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Qing Li
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Xin Zhu
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Zhiqin Xi
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Zusha Qiao
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
| | - Wen Cen
- Department of Dermatovenereology, The Second Hospital of Shanxi Medical University, Taiyuan, Shanxi 030001, P.R. China
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Candida albicans Swi/Snf and Mediator Complexes Differentially Regulate Mrr1-Induced MDR1 Expression and Fluconazole Resistance. Antimicrob Agents Chemother 2017; 61:AAC.01344-17. [PMID: 28807921 DOI: 10.1128/aac.01344-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/09/2017] [Indexed: 02/07/2023] Open
Abstract
Long-term azole treatment of patients with chronic Candida albicans infections can lead to drug resistance. Gain-of-function (GOF) mutations in the transcription factor Mrr1 and the consequent transcriptional activation of MDR1, a drug efflux coding gene, is a common pathway by which this human fungal pathogen acquires fluconazole resistance. This work elucidates the previously unknown downstream transcription mechanisms utilized by hyperactive Mrr1. We identified the Swi/Snf chromatin remodeling complex as a key coactivator for Mrr1, which is required to maintain basal and induced open chromatin, and Mrr1 occupancy, at the MDR1 promoter. Deletion of snf2, the catalytic subunit of Swi/Snf, largely abrogates the increases in MDR1 expression and fluconazole MIC observed in MRR1GOF mutant strains. Mediator positively and negatively regulates key Mrr1 target promoters. Deletion of the Mediator tail module med3 subunit reduces, but does not eliminate, the increased MDR1 expression and fluconazole MIC conferred by MRR1GOF mutations. Eliminating the kinase activity of the Mediator Ssn3 subunit suppresses the decreased MDR1 expression and fluconazole MIC of the snf2 null mutation in MRR1GOF strains. Ssn3 deletion also suppresses MDR1 promoter histone displacement defects in snf2 null mutants. The combination of this work with studies on other hyperactive zinc cluster transcription factors that confer azole resistance in fungal pathogens reveals a complex picture where the induction of drug efflux pump expression requires the coordination of multiple coactivators. The observed variations in transcription factor and target promoter dependence of this process may make the search for azole sensitivity-restoring small molecules more complicated.
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Quinone derivatives isolated from the endolichenic fungus Phialocephala fortinii are Mdr1 modulators that combat azole resistance in Candida albicans. Sci Rep 2016; 6:33687. [PMID: 27650180 PMCID: PMC5030645 DOI: 10.1038/srep33687] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/30/2016] [Indexed: 11/09/2022] Open
Abstract
One of the main azole-resistance mechanisms in Candida pathogens is the upregulation of drug efflux pumps, which compromises the efficacy of azoles and results in treatment failure. The combination of azole-antifungal agents with efflux pump inhibitors represents a promising strategy to combat fungal infection. High-throughput screening of 150 extracts obtained from endolichenic fungal cultures led to the discovery that the extract of Phialocephala fortinii exhibits potent activity for the reversal of azole resistance. From P. fortinii cultures, a total of 15 quinone derivatives, comprising 11 new derivatives and 4 known compounds, were obtained. Among these compounds, palmarumycin P3 (3) and phialocephalarin B (8) specifically modulate the expression of MDR1 to inhibit the activity of drug efflux pumps and therefore reverse azole resistance. The present study revealed Mdr1 targeting as an alternative mechanism for the discovery of new agents to fight antifungal drug resistance.
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Ford CB, Funt JM, Abbey D, Issi L, Guiducci C, Martinez DA, Delorey T, Li BY, White TC, Cuomo C, Rao RP, Berman J, Thompson DA, Regev A. The evolution of drug resistance in clinical isolates of Candida albicans. eLife 2015; 4:e00662. [PMID: 25646566 PMCID: PMC4383195 DOI: 10.7554/elife.00662] [Citation(s) in RCA: 196] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 12/18/2014] [Indexed: 12/31/2022] Open
Abstract
Candida albicans is both a member of the healthy human microbiome
and a major pathogen in immunocompromised individuals. Infections are typically
treated with azole inhibitors of ergosterol biosynthesis often leading to drug
resistance. Studies in clinical isolates have implicated multiple mechanisms in
resistance, but have focused on large-scale aberrations or candidate genes, and do
not comprehensively chart the genetic basis of adaptation. Here, we leveraged
next-generation sequencing to analyze 43 isolates from 11 oral candidiasis patients.
We detected newly selected mutations, including single-nucleotide polymorphisms
(SNPs), copy-number variations and loss-of-heterozygosity (LOH) events. LOH events
were commonly associated with acquired resistance, and SNPs in 240 genes may be
related to host adaptation. Conversely, most aneuploidies were transient and did not
correlate with drug resistance. Our analysis also shows that isolates also varied in
adherence, filamentation, and virulence. Our work reveals new molecular mechanisms
underlying the evolution of drug resistance and host adaptation. DOI:http://dx.doi.org/10.7554/eLife.00662.001 Nearly all humans are infected with the fungus Candida albicans. In
most people, the infection does not produce any symptoms because their immune system
is able to counteract the fungus' attempts to spread around the body. However, if the
balance between fungal attack and body defence fails, the fungus is able to spread,
which can lead to serious disease that is fatal in 42% of cases. How does C. albicans outcompete the body's defences to cause
disease? This is a pertinent question because the most effective antifungal
medicines—including the drug fluconazole—do not kill the fungus; they
only stop it from growing. This gives the fungus time to develop resistance to the
drug by becoming able to quickly replace the fungal proteins the drug destroys, or to
efficiently remove the drug from its cells. In this study, Ford et al. studied the changes that occur in the DNA of C.
albicans over time in patients who are being treated with fluconazole.
Ford et al. took 43 samples of C. albicans from 11 patients with
weakened immune systems. The experiments show that the fungus samples collected early
on were more sensitive to the drug than the samples collected later. In most cases, the genetic data suggest that the infections begin with a single
fungal cell; the cells in the later samples are its offspring. Despite this, there is
a lot of genetic variation between samples from the same patient, which indicates
that the fungus is under pressure to become more resistant to the drug. There were
240 genes—including those that can alter the surface on the fungus cells to
make it better at evading the host immune system—in which small changes
occurred over time in three or more patients. Laboratory tests revealed that many of
these genes are likely important for the fungus to survive in an animal host in the
presence of the drug. C. albicans cells usually have two genetically distinct copies of
every gene. Ford et al. found that for some genes—including some that make
surface components or are involved in expelling drugs from cells—the loss of
genetic information from one copy, so that both copies become identical, is linked to
resistance to fluconazole. However, the gain of whole or partial
chromosomes—which contain large numbers of genes—is not linked to
resistance, but may provide additional genetic material for generating diversity in
the yeast population that may help the cells to evolve resistance in the future. These experiments have identified many new candidate genes that are important for
drug resistance and evading the host immune system, and which could be used to guide
the development of new therapeutics to treat these life-threatening infections. DOI:http://dx.doi.org/10.7554/eLife.00662.002
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Affiliation(s)
- Christopher B Ford
- Department of Biology, Broad Institute of MIT and Harvard, Cambridge, United States
| | - Jason M Funt
- Department of Biology, Broad Institute of MIT and Harvard, Cambridge, United States
| | - Darren Abbey
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Luca Issi
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, United States
| | | | | | - Toni Delorey
- Broad Institute of MIT and Harvard, Cambridge, United States
| | - Bi Yu Li
- Broad Institute of MIT and Harvard, Cambridge, United States
| | - Theodore C White
- School of Biological Sciences, University of Missouri at Kansas City, Kansas City, United States
| | - Christina Cuomo
- Broad Institute of MIT and Harvard, Cambridge, United States
| | - Reeta P Rao
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, United States
| | - Judith Berman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, United States
| | - Dawn A Thompson
- Broad Institute of MIT and Harvard, Cambridge, United States
| | - Aviv Regev
- Department of Biology, Broad Institute of MIT and Harvard, Cambridge, United States
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Xie JL, Polvi EJ, Shekhar-Guturja T, Cowen LE. Elucidating drug resistance in human fungal pathogens. Future Microbiol 2014; 9:523-42. [PMID: 24810351 DOI: 10.2217/fmb.14.18] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Fungal pathogens cause life-threatening infections in immunocompetent and immunocompromised individuals. Millions of people die each year due to fungal infections, comparable to the mortality attributable to tuberculosis or malaria. The three most prevalent fungal pathogens are Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. Fungi are eukaryotes like their human host, making it challenging to identify fungal-specific therapeutics. There is a limited repertoire of antifungals in clinical use, and drug resistance and host toxicity compromise the clinical utility. The three classes of antifungals for treatment of invasive infections are the polyenes, azoles and echinocandins. Understanding mechanisms of resistance to these antifungals has been accelerated by global and targeted approaches, which have revealed that antifungal drug resistance is a complex phenomenon involving multiple mechanisms. Development of novel strategies to block the emergence of drug resistance and render resistant pathogens responsive to antifungals will be critical to treating life-threatening fungal infections.
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Affiliation(s)
- Jinglin Lucy Xie
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Induction of Candida albicans drug resistance genes by hybrid zinc cluster transcription factors. Antimicrob Agents Chemother 2014; 59:558-69. [PMID: 25385116 DOI: 10.1128/aac.04448-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The pathogenic yeast Candida albicans can develop resistance to azole antifungal drugs by overexpressing ERG11, which encodes the drug target, or the multidrug efflux pumps MDR1 and CDR1/CDR2. The constitutive upregulation of these genes is usually caused by gain-of-function mutations in the zinc cluster transcription factors Upc2, Mrr1, and Tac1, respectively. These transcription factors are also required for the induction of their target genes in drug-susceptible strains in the presence of specific stimuli. By swapping the DNA-binding domains of Mrr1, Tac1, and Upc2 we investigated if the hybrid transcription factors could activate their new target genes in response to the same signals. When Tac1 was targeted to the MDR1 and ERG11 promoters, the expression of these genes became inducible by fluphenazine. Similarly, MDR1 and CDR2 were strongly upregulated by fluconazole when Upc2 was fused to the DNA-binding domains of Mrr1 and Tac1, respectively. In contrast, Mrr1 was unable to promote gene expression in response to benomyl when it was targeted to the CDR2 and ERG11 promoters instead of the MDR1 promoter. These results suggest that Tac1 and Upc2 themselves are activated by the inducers fluphenazine and fluconazole, respectively, whereas benomyl does not activate Mrr1 itself but a coregulatory factor that is present at the promoters of Mrr1 target genes. Strains in which the expression levels of Mrr1 and Tac1 target genes were controlled by Upc2 exhibited increased fluconazole resistance, demonstrating that the ability to efficiently upregulate the expression of efflux pumps in the presence of the drug results in enhanced intrinsic fluconazole resistance.
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Disruption of the transcriptional regulator Cas5 results in enhanced killing of Candida albicans by Fluconazole. Antimicrob Agents Chemother 2014; 58:6807-18. [PMID: 25182640 DOI: 10.1128/aac.00064-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Azole antifungal agents such as fluconazole exhibit fungistatic activity against Candida albicans. Strategies to enhance azole antifungal activity would be therapeutically appealing. In an effort to identify transcriptional pathways that influence the killing activity of fluconazole, we sought to identify transcription factors (TFs) involved in this process. From a collection of C. albicans strains disrupted for genes encoding TFs (O. R. Homann, J. Dea, S. M. Noble, and A. D. Johnson, PLoS Genet. 5:e1000783, 2009, http://dx.doi.org/10.1371/journal.pgen.1000783), four strains exhibited marked reductions in minimum fungicidal concentration (MFCs) in both RPMI and yeast extract-peptone-dextrose (YPD) media. One of these genes, UPC2, was previously characterized with regard to its role in azole susceptibility. Of mutants representing the three remaining TF genes of interest, one (CAS5) was unable to recover from fluconazole exposure at concentrations as low as 2 μg/ml after 72 h in YPD medium. This mutant also showed reduced susceptibility and a clear zone of inhibition by Etest, was unable to grow on solid medium containing 10 μg/ml fluconazole, and exhibited increased susceptibility by time-kill analysis. CAS5 disruption in highly azole-resistant clinical isolates exhibiting multiple resistance mechanisms did not alter susceptibility. However, CAS5 disruption in strains with specific resistance mutations resulted in moderate reductions in MICs and MFCs. Genome-wide transcriptional analysis was performed in the presence of fluconazole and was consistent with the suggested role of CAS5 in cell wall organization while also suggesting a role in iron transport and homeostasis. These findings suggest that Cas5 regulates a transcriptional network that influences the response of C. albicans to fluconazole. Further delineation of this transcriptional network may identify targets for potential cotherapeutic strategies to enhance the activity of the azole class of antifungals.
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SAGA/ADA complex subunit Ada2 is required for Cap1- but not Mrr1-mediated upregulation of the Candida albicans multidrug efflux pump MDR1. Antimicrob Agents Chemother 2014; 58:5102-10. [PMID: 24936593 DOI: 10.1128/aac.03065-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Overexpression of the multidrug efflux pump MDR1 is one mechanism by which the pathogenic yeast Candida albicans develops resistance to the antifungal drug fluconazole. The constitutive upregulation of MDR1 in fluconazole-resistant, clinical C. albicans isolates is caused by gain-of-function mutations in the zinc cluster transcription factor Mrr1. It has been suggested that Mrr1 activates MDR1 transcription by recruiting Ada2, a subunit of the SAGA/ADA coactivator complex. However, MDR1 expression is also regulated by the bZIP transcription factor Cap1, which mediates the oxidative stress response in C. albicans. Here, we show that a hyperactive Mrr1 containing a gain-of-function mutation promotes MDR1 overexpression independently of Ada2. In contrast, a C-terminally truncated, hyperactive Cap1 caused MDR1 overexpression in a wild-type strain but only weakly in mutants lacking ADA2. In the presence of benomyl or H2O2, compounds that induce MDR1 expression in an Mrr1- and Cap1-dependent fashion, MDR1 was upregulated with the same efficiency in wild-type and ada2Δ cells. These results indicate that Cap1, but not Mrr1, recruits Ada2 to the MDR1 promoter to induce the expression of this multidrug efflux pump and that Ada2 is not required for MDR1 overexpression in fluconazole-resistant C. albicans strains containing gain-of-function mutations in Mrr1.
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Paul S, Moye-Rowley WS. Multidrug resistance in fungi: regulation of transporter-encoding gene expression. Front Physiol 2014; 5:143. [PMID: 24795641 PMCID: PMC3997011 DOI: 10.3389/fphys.2014.00143] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 03/25/2014] [Indexed: 11/24/2022] Open
Abstract
A critical risk to the continued success of antifungal chemotherapy is the acquisition of resistance; a risk exacerbated by the few classes of effective antifungal drugs. Predictably, as the use of these drugs increases in the clinic, more resistant organisms can be isolated from patients. A particularly problematic form of drug resistance that routinely emerges in the major fungal pathogens is known as multidrug resistance. Multidrug resistance refers to the simultaneous acquisition of tolerance to a range of drugs via a limited or even single genetic change. This review will focus on recent progress in understanding pathways of multidrug resistance in fungi including those of most medical relevance. Analyses of multidrug resistance in Saccharomyces cerevisiae have provided the most detailed outline of multidrug resistance in a eukaryotic microorganism. Multidrug resistant isolates of S. cerevisiae typically result from changes in the activity of a pair of related transcription factors that in turn elicit overproduction of several target genes. Chief among these is the ATP-binding cassette (ABC)-encoding gene PDR5. Interestingly, in the medically important Candida species, very similar pathways are involved in acquisition of multidrug resistance. In both C. albicans and C. glabrata, changes in the activity of transcriptional activator proteins elicits overproduction of a protein closely related to S. cerevisiae Pdr5 called Cdr1. The major filamentous fungal pathogen, Aspergillus fumigatus, was previously thought to acquire resistance to azole compounds (the principal antifungal drug class) via alterations in the azole drug target-encoding gene cyp51A. More recent data indicate that pathways in addition to changes in the cyp51A gene are important determinants in A. fumigatus azole resistance. We will discuss findings that suggest azole resistance in A. fumigatus and Candida species may share more mechanistic similarities than previously thought.
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Affiliation(s)
- Sanjoy Paul
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa Iowa City, IA, USA
| | - W Scott Moye-Rowley
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa Iowa City, IA, USA
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UPC2 is universally essential for azole antifungal resistance in Candida albicans. EUKARYOTIC CELL 2014; 13:933-46. [PMID: 24659578 DOI: 10.1128/ec.00221-13] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In Candida albicans, the transcription factor Upc2 is central to the regulation of ergosterol biosynthesis. UPC2-activating mutations contribute to azole resistance, whereas disruption increases azole susceptibility. In the present study, we investigated the relationship of UPC2 to fluconazole susceptibility, particularly in azole-resistant strains. In addition to the reduced fluconazole MIC previously observed with UPC2 disruption, we observed a lower minimum fungicidal concentration (MFC) for a upc2Δ/Δ mutant than for its azole-susceptible parent, SC5314. Moreover, the upc2Δ/Δ mutant was unable to grow on a solid medium containing 10 μg/ml fluconazole and exhibited increased susceptibility and a clear zone of inhibition by Etest. Time-kill analysis showed higher fungistatic activity against the upc2Δ/Δ mutant than against SC5314. UPC2 disruption in strains carrying specific resistance mutations also resulted in reduced MICs and MFCs. UPC2 disruption in a highly azole resistant clinical isolate containing multiple resistance mechanisms likewise resulted in a reduced MIC and MFC. This mutant was unable to grow on a solid medium containing 10 μg/ml fluconazole and exhibited increased susceptibility and a clear zone of inhibition by Etest. Time-kill analysis showed increased fungistatic activity against the upc2Δ/Δ mutant in the resistant background. Microarray analysis showed attenuated induction by fluconazole of genes involved in sterol biosynthesis, iron transport, or iron homeostasis in the absence of UPC2. Taken together, these data demonstrate that the UPC2 transcriptional network is universally essential for azole resistance in C. albicans and represents an attractive target for enhancing azole antifungal activity.
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Deciphering azole resistance mechanisms with a focus on transcription factor-encoding genes TAC1, MRR1 and UPC2 in a set of fluconazole-resistant clinical isolates of Candida albicans. Int J Antimicrob Agents 2013; 42:410-5. [DOI: 10.1016/j.ijantimicag.2013.07.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/04/2013] [Accepted: 07/26/2013] [Indexed: 11/20/2022]
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Schillig R, Morschhäuser J. Analysis of a fungus-specific transcription factor family, theCandida albicanszinc cluster proteins, by artificial activation. Mol Microbiol 2013; 89:1003-17. [DOI: 10.1111/mmi.12327] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2013] [Indexed: 12/13/2022]
Affiliation(s)
- Rebecca Schillig
- Institut für Molekulare Infektionsbiologie; Universität Würzburg; Würzburg; Germany
| | - Joachim Morschhäuser
- Institut für Molekulare Infektionsbiologie; Universität Würzburg; Würzburg; Germany
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Eddouzi J, Lohberger A, Vogne C, Manai M, Sanglard D. Identification and antifungal susceptibility of a large collection of yeast strains isolated in Tunisian hospitals. Med Mycol 2013; 51:737-46. [PMID: 23768242 DOI: 10.3109/13693786.2013.800239] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a rapid method to identify yeasts isolated from patients in Tunisian hospitals. When identification could not be exstablished with this procedure, sequencing of the internal transcribed spacer with 5.8S ribosomal DNA (rDNA) (ITS1-5.8S-ITS2) and D1/D2 domain of large-subunit (LSU rDNA) were employed as a molecular approach for species differentiation. Candida albicans was the dominant species (43.37% of all cases), followed by C. glabrata (16.55%), C. parapsilosis (13.23%), C. tropicalis (11.34%), C. dubliniensis (4.96%), and other species more rarely encountered in human diseases such as C. krusei, C. metapsilosis, C. lusitaniae, C. kefyr, C. palmioleophila, C. guilliermondii, C. intermedia, C. orthopsilosis, and C. utilis. In addition, other yeast species were obtained including Saccharomyces cerevisiae, Debaryomyces hansenii (anamorph known as C. famata), Hanseniaspora opuntiae, Kodamaea ohmeri, Pichia caribbica (anamorph known as C. fermentati), Trichosporon spp. and finally a novel yeast species, C. tunisiensis. The in vitro antifungal activities of fluconazole and voriconazole were determined by the agar disk diffusion test and Etest, while the susceptibility to additional antifungal agents was determined with the Sensititre YeastOne system. Our results showed low incidence of azole resistance in C. albicans (0.54%), C. tropicalis (2.08%) and C. glabrata (4.28%). In addition, caspofungin was active against most isolates of the collection with the exception of two K. ohmeri isolates. This is the first report to describe caspofungin resistant isolates of this yeast.
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Affiliation(s)
- Jamel Eddouzi
- * Institute of Microbiology, University Hospital Lausanne and University Hospital Center , Lausanne , Switzerland
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Inducible and constitutive activation of two polymorphic promoter alleles of the Candida albicans multidrug efflux pump MDR1. Antimicrob Agents Chemother 2012; 56:4490-4. [PMID: 22615278 DOI: 10.1128/aac.00264-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Overexpression of the multidrug efflux pump MDR1 confers resistance to the antifungal drug fluconazole on Candida albicans. It has been reported that two types of MDR1 promoters exist in C. albicans and that homozygosity for the allele with higher activity may promote fluconazole resistance. We found that the two MDR1 promoter alleles in strain SC5314 were equally well activated by inducing chemicals or hyperactive forms of the transcription factors Mrr1 and Cap1, which control MDR1 expression. In addition, no loss of heterozygosity at the MDR1 locus was observed in MDR1-overexpressing clinical C. albicans strains that developed fluconazole resistance during therapy.
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