Project description:The leucine CUG codon was reassigned to serine in the fungal pathogen Candida albicans. To clarify the biological role of this tuneable codon ambiguity on drug resistance, we evolved C. albicans strains that were engineered to mistranslate the CUG codon at constitutively elevated levels, in the presence and absence of the antifungal drug fluconazole. Elevated levels of mistranslation resulted in the rapid acquisition of resistance to fluconazole.
2016-10-27 | E-SYBR-13 | biostudies-arrayexpress
Project description:Drug resistance induction in Candida glabrata
Project description:Comparative analysis of genome wide binding profile of Ncb2 in azole sensitive (AS, Gu4) and azole resistant (AR, Gu5) clinical isolates of Candida albicans. The goal was to study the role of Ncb2 in acquisition of drug resistance by comparing the binding profiles of Ncb2 in both the isolates.
Project description:Aneuploidy and the evolution of aneuploid karyotypes of Candida albicans strains was identified using aCGH. Whole chromosome and segmental aneuploidies, (specifically on the left arm of chromosome 5 - shown to be due to isochromosome formation) are associated with the appearance of resistance to the antifungal drug fluconazole. Keywords: Comparative Genomic Hybridization
Project description:Drug susceptible clinical isolates of Candida albicans frequently become highly tolerant to drugs during chemotherapy, with dreadful consequences on patient health. We used RNA sequencing (RNA-seq) to analyze the transcriptomes of a CDR (Candida Drug Resistance) strain and its isogenic drug sensitive counterpart. RNA-seq unveiled differential expression of 228 genes including a) genes previously identified as involved in CDR, b) genes not previously associated to the CDR phenotype, and c) novel transcripts whose function as a gene is uncharacterized. In particular, we show for the first time that CDR acquisition is correlated with an overexpression of the transcription factor encoding gene CZF1. CZF1 null mutants were sensitive to many drugs, independently of known multidrug resistance mechanisms. We show that CZF1 acts as a repressor of M-NM-2-glucan synthesis, thus negatively regulating cell wall integrity. Finally, our RNA-seq data allowed us to identify a new transcribed region, upstream of the TAC1 gene, which encodes the major CDR transcriptional regulator. Our results open new perspectives to the role of Czf1 and to our understanding of the transcriptional and post-transcriptional mechanisms that lead to the acquisition of drug resistance in C. albicans, with potential future improvements of therapeutic strategies. RNA sequencing was performed on 2 Candida albicans strains (Gu4 and Gu5). For each strain, we sequenced 2 biological replicates.
Project description:The fungal pathogen Candida albicans and other pathogens of the CTG clade reassigned the leucine CUG codon to serine and tolerate highly variable levels of both serine and leucine at CUG positions in response to environmental cues. Previous studies found that increased leucine misincorporation levels enhance resistance to drugs but the underlying mechanisms are not known. To clarify the biological role of this tuneable codon ambiguity, we evolved C. albicans strains engineered to mistranslate CUG at elevated levels, in the presence and absence of the antifungal drug fluconazole
Project description:Candida albicans lab strain SC5314 was spread on YPD+uniconazole (0.06-4μg/mL) plates. Randomly 4 adaptors from each drug plate were sequenced.
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.
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.
Project description:Drug susceptible clinical isolates of Candida albicans frequently become highly tolerant to drugs during chemotherapy, with dreadful consequences on patient health. We used RNA sequencing (RNA-seq) to analyze the transcriptomes of a CDR (Candida Drug Resistance) strain and its isogenic drug sensitive counterpart. RNA-seq unveiled differential expression of 228 genes including a) genes previously identified as involved in CDR, b) genes not previously associated to the CDR phenotype, and c) novel transcripts whose function as a gene is uncharacterized. In particular, we show for the first time that CDR acquisition is correlated with an overexpression of the transcription factor encoding gene CZF1. CZF1 null mutants were sensitive to many drugs, independently of known multidrug resistance mechanisms. We show that CZF1 acts as a repressor of β-glucan synthesis, thus negatively regulating cell wall integrity. Finally, our RNA-seq data allowed us to identify a new transcribed region, upstream of the TAC1 gene, which encodes the major CDR transcriptional regulator. Our results open new perspectives to the role of Czf1 and to our understanding of the transcriptional and post-transcriptional mechanisms that lead to the acquisition of drug resistance in C. albicans, with potential future improvements of therapeutic strategies.