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:Candida albicans is a leading cause of fungal infections in immunocompromised patients. Management of candidemia relies on a few antifungal agents, with fluconazole being first line therapy. The emergence of fluconazole-resistant strains highlights the pressing need to improve our molecular understanding of the drug response mechanisms. By sequencing the 5’P mRNA degradation intermediates, we show that co-translational mRNA decay is common in C. albicans and characterize how in vivo 5´-3´ exonuclease degradation trails the last translating ribosome. Thus, the study of the 5'P mRNA degradome (5PSeq) offers a simple and affordable way to measure ribosome dynamics and identify codon specific ribosome stalls in response to drugs and amino acid deprivation. Building upon this, we combine RNA-Seq and 5PSeq to study the early response of sensitive and resistant C. albicans isolates to fluconazole. Our results highlight that transcriptional responses, rather than changes in ribosome dynamics, are the main driver of Candida resistance to fluconazole.
Project description:Candida albicans is a leading cause of fungal infections in immunocompromised patients. Management of candidemia relies on a few antifungal agents, with fluconazole being first line therapy. The emergence of fluconazole-resistant strains highlights the pressing need to improve our molecular understanding of the drug response mechanisms. By sequencing the 5’P mRNA degradation intermediates, we show that co-translational mRNA decay is common in C. albicans and characterize how in vivo 5´-3´ exonuclease degradation trails the last translating ribosome. Thus, the study of the 5'P mRNA degradome (5PSeq) offers a simple and affordable way to measure ribosome dynamics and identify codon specific ribosome stalls in response to drugs and amino acid deprivation. Building upon this, we combine RNA-Seq and 5PSeq to study the early response of sensitive and resistant C. albicans isolates to fluconazole. Our results highlight that transcriptional responses, rather than changes in ribosome dynamics, are the main driver of Candida resistance to fluconazole.
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.
Project description:Candida albicans lab strain SC5314 was daily passaged in YPD broth supplemented with fluconazole. Some fluconazole-resistant and some fluconazole-tolerant adaptors were sequenced.
Project description:To investigate the effect of METRNL on macrophages phagocytosis and killing of Candida albicans, we designed RNA-Seq analysis of macrophages pretreated with vehicle or rmMETRNL challenged with Candida albicans for 6 hours in vitro.
Project description: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 fluconazole susceptibility, we sought to identify transcription factors (TFs) involved in this process. From a collection of C. albicans strains disrupted for genes encoding TFs (Homann et al., PLoS Genet. 2009;5:e1000783), four exhibited a marked reduction in minimum fungicidal concentration (MFC) in both RPMI and YPD media. One of these, UPC2, has been 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 hours in YPD medium. This mutant also showed reduced susceptibility and a clear zone of inhibition by Etest, was unable to grow on solid media 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 in ergosterol biosynthesis or efflux pumps resulted in a moderate reduction in MIC and MFC. 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 susceptibility of C. albicans to fluconazole. Further delineation of this transcriptional network may identify targets for potential co-therapeutic strategies to enhance the activity to the azole class of antifungals.
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.