Candida albicans
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PROVIDER: PRJNA131763 | ENA |
REPOSITORIES: ENA
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Project description:Constitutive overexpression of the Mdr1 efflux pump is an important mechanism of acquired drug resistance in the yeast Candida albicans. The zinc cluster transcription factor Mrr1 is a central regulator of MDR1 expression, but other transcription factors have also been implicated in MDR1 regulation. To better understand how MDR1-mediated drug resistance is achieved in this important fungal pathogen, we studied the interdependence of Mrr1 and two other MDR1 regulators, Upc2 and Cap1, in the control of MDR1 expression. A mutated, constitutively active Mrr1 could upregulate MDR1 and confer drug resistance in the absence of Upc2 or Cap1. On the other hand, Upc2 containing a gain-of-function mutation only slightly activated the MDR1 promoter, and this activation depended on the presence of a functional MRR1 gene. In contrast, a C-terminally truncated, activated form of Cap1 could upregulate MDR1 in a partially Mrr1-independent fashion. The induction of MDR1 expression by toxic chemicals occurred independently of Upc2, but required the presence of Mrr1 and also partially depended on Cap1. Transcriptional profiling and in vivo DNA binding studies showed that a constitutively active Mrr1 binds to and upregulates most of its direct target genes in the presence or absence of Cap1. Therefore, Mrr1 and Cap1 cooperate in the environmental induction of MDR1 expression in wild-type C. albicans, but gain-of-function mutations in either of the two transcription factors can independently mediate efflux pump overexpression and drug resistance.
2011-07-01 | GSE23532 | GEO
Project description:Constitutive overexpression of the Mdr1 efflux pump is an important mechanism of acquired drug resistance in the yeast Candida albicans. The zinc cluster transcription factor Mrr1 is a central regulator of MDR1 expression, but other transcription factors have also been implicated in MDR1 regulation. To better understand how MDR1-mediated drug resistance is achieved in this important fungal pathogen, we studied the interdependence of Mrr1 and two other MDR1 regulators, Upc2 and Cap1, in the control of MDR1 expression. A mutated, constitutively active Mrr1 could upregulate MDR1 and confer drug resistance in the absence of Upc2 or Cap1. On the other hand, Upc2 containing a gain-of-function mutation only slightly activated the MDR1 promoter, and this activation depended on the presence of a functional MRR1 gene. In contrast, a C-terminally truncated, activated form of Cap1 could upregulate MDR1 in a partially Mrr1-independent fashion. The induction of MDR1 expression by toxic chemicals occurred independently of Upc2, but required the presence of Mrr1 and also partially depended on Cap1. Transcriptional profiling and in vivo DNA binding studies showed that a constitutively active Mrr1 binds to and upregulates most of its direct target genes in the presence or absence of Cap1. Therefore, Mrr1 and Cap1 cooperate in the environmental induction of MDR1 expression in wild-type C. albicans, but gain-of-function mutations in either of the two transcription factors can independently mediate efflux pump overexpression and drug resistance. We endeavored to determine how the function of a gain-of-function allele of MRR1 (shown to confer high-level azole resistance) is affected when the CAP1 gene is disrupted.
2011-07-01 | E-GEOD-23532 | biostudies-arrayexpress
Project description:In Candida albicans, Upc2 is a zinc-cluster transcription factor that targets genes including those of the ergosterol biosynthesis pathway. To date there have been three documented UPC2 gain-of-function (GOF) mutations recovered from fluconazole-resistant clinical isolates that contribute to an increase in ERG11 expression and decreased fluconazole susceptibility. In a group of 62 fluconazole-resistant isolates, we found that 47 of these overexpressed ERG11 by at least two-fold over that of an average expression of 3 unrelated fluconazole susceptible strains. Of those 47 isolates, 29 contained a mutation in UPC2, whereas the remaining 18 isolates did not. Of the isolates containing mutations in UPC2, we recovered eight distinct mutations resulting in single putative amino acid substitutions: G648D, G648S, A643T, A643V, Y642F, G304R, A646V and W478C. Seven of these resulted in increased ERG11 expression, increased cellular ergosterol, and decreased susceptibility to fluconazole as compared to the wild-type strain. Genome-wide transcriptional analysis was performed for the four strongest Upc2 amino acid substitutions (A643V, G648D, G648S and Y642F). Genes commonly upregulated in all four mutations included those involved in ergosterol biosynthesis, in oxidoreductase activity, the major facilitator efflux pump encoded by the MDR1 gene, and the uncharacterized ATP binding cassette transporter CDR11. These findings demonstrate that gain-of-function mutations in UPC2 are more prevalent than previously thought among clinical isolates, make a significant contribution to azole antifungal resistance, but do not account for ERG11 overexpression in all such isolates of C. albicans.
2013-01-31 | GSE39201 | GEO
Project description:This SuperSeries is composed of the following subset Series: GSE24073: Transcriptional profile of Candida albicans during Hypoxic conditions. GSE24074: Transcriptional profile of Candida albicans DAY286 culture without ketoconazole versus DAY286 culture with 0.04 μg/ml ketoconazole, both at 20% oxygen (normoxia). GSE24075: Transcriptional profile of Candida albicans DAY286 versus UPC2 delete, both at 1% oxygen (hypoxia). Refer to individual Series
2010-11-15 | E-GEOD-24076 | biostudies-arrayexpress
Project description:In Candida albicans, Upc2 is a zinc-cluster transcription factor that targets genes including those of the ergosterol biosynthesis pathway. To date there have been three documented UPC2 gain-of-function (GOF) mutations recovered from fluconazole-resistant clinical isolates that contribute to an increase in ERG11 expression and decreased fluconazole susceptibility. In a group of 62 fluconazole-resistant isolates, we found that 47 of these overexpressed ERG11 by at least two-fold over that of an average expression of 3 unrelated fluconazole susceptible strains. Of those 47 isolates, 29 contained a mutation in UPC2, whereas the remaining 18 isolates did not. Of the isolates containing mutations in UPC2, we recovered eight distinct mutations resulting in single putative amino acid substitutions: G648D, G648S, A643T, A643V, Y642F, G304R, A646V and W478C. Seven of these resulted in increased ERG11 expression, increased cellular ergosterol, and decreased susceptibility to fluconazole as compared to the wild-type strain. Genome-wide transcriptional analysis was performed for the four strongest Upc2 amino acid substitutions (A643V, G648D, G648S and Y642F). Genes commonly upregulated in all four mutations included those involved in ergosterol biosynthesis, in oxidoreductase activity, the major facilitator efflux pump encoded by the MDR1 gene, and the uncharacterized ATP binding cassette transporter CDR11. These findings demonstrate that gain-of-function mutations in UPC2 are more prevalent than previously thought among clinical isolates, make a significant contribution to azole antifungal resistance, but do not account for ERG11 overexpression in all such isolates of C. albicans. We examined the expression of genes in response to the presence of 4 gain-of-function alleles of the zinc-cluster transcription factor Upc2. The global gene expression of each mutant Upc2 strain was compared to that of the wildtype strain SC5314.
2013-01-31 | E-GEOD-39201 | biostudies-arrayexpress
Project description:The zinc cluster proteins are a family of transcription factors that are unique to the fungal kingdom. In the pathogenic yeast Candida albicans, zinc cluster transcription factors control the expression of virulence-associated traits and play key roles in the development of antifungal drug resistance. Gain-of-function mutations in several zinc cluster transcription factors, which result in constitutive overexpression of their target genes, are a frequent cause of azole resistance in clinical C. albicans isolates. We found that zinc cluster proteins can also be artificially activated by C-terminal fusion with the heterologous Gal4 activation domain. We used this strategy to create a comprehensive library of C. albicans strains expressing all 82 zinc cluster transcription factors of this fungus in a potentially hyperactive form. Screening of this library identified regulators of invasive filamentous growth and other phenotypes that are important during an infection. In addition, the approach uncovered several novel mediators of fluconazole resistance, including the multidrug resistance regulator Mrr2, which controls the expression of the major C. albicans multidrug efflux pump CDR1. Artificial activation therefore is a highly useful method to study the role of zinc cluster transcription factors in C. albicans and other fungi of medical, agricultural, and biotechnological importance.
2013-07-29 | GSE48259 | GEO
Project description: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.
2014-05-24 | GSE57929 | GEO
Project description:The zinc cluster proteins are a family of transcription factors that are unique to the fungal kingdom. In the pathogenic yeast Candida albicans, zinc cluster transcription factors control the expression of virulence-associated traits and play key roles in the development of antifungal drug resistance. Gain-of-function mutations in several zinc cluster transcription factors, which result in constitutive overexpression of their target genes, are a frequent cause of azole resistance in clinical C. albicans isolates. We found that zinc cluster proteins can also be artificially activated by C-terminal fusion with the heterologous Gal4 activation domain. We used this strategy to create a comprehensive library of C. albicans strains expressing all 82 zinc cluster transcription factors of this fungus in a potentially hyperactive form. Screening of this library identified regulators of invasive filamentous growth and other phenotypes that are important during an infection. In addition, the approach uncovered several novel mediators of fluconazole resistance, including the multidrug resistance regulator Mrr2, which controls the expression of the major C. albicans multidrug efflux pump CDR1. Artificial activation therefore is a highly useful method to study the role of zinc cluster transcription factors in C. albicans and other fungi of medical, agricultural, and biotechnological importance. In total, 15 samples are analysed: 3 replicates of 5 different strains. The 3 replicates of SC5314 are the wild type reference.
2013-07-29 | E-GEOD-48259 | biostudies-arrayexpress
Project description:Abstract: Candida parapsilosis and Candida albicans are human fungal pathogens that belong to the CUG clade in the Saccharomycotina. In contrast to C. albicans, relatively little is known about the virulence properties of C. parapsilosis, a pathogen particularly associated with infections of premature neonates. We describe here the construction of >200 C. parapsilosis strains carrying double allele deletions of transcription factors, protein kinases and species-specific genes. Two independent deletions were constructed for each target gene. Growth in > 40 conditions was tested, including carbon source, temperature, and the presence of antifungal drugs. The phenotypes were compared to C. albicans strains with deletions of orthologous transcription factors. We found that many phenotypes are shared between the two species, such as the role of Upc2 as a regulator of azole resistance. Others are unique. For example, Cph2 plays a role in the hypoxic response in C. parapsilosis and not in C. albicans. We found extensive divergence between the biofilm regulators of the two species. We identified 7 transcription factors and one protein kinase that are required for biofilm development in C. parapsilosis. Only three (Efg1, Bcr1, and Ace2) have similar effects on C. albicans biofilms, whereas Cph2, Czf1, Gzf3 and Ume6 have major roles in C. parapsilosis only. In addition, two transcription factors (Brg1 and Tec1) with well-characterized roles in biofilm formation in C. albicans do not have the same function in C. parapsilosis. We also compared the transcription profile of C. parapsilosis and C. albicans biofilms. Our analysis suggests the processes shared between the two species are predominantly metabolic.
2014-07-21 | GSE57451 | GEO
Project description:UPC2 Is universally essential for Azole antifungal resistance in Candida albicans
| PRJNA248441 | ENA