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The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.


Related in: MedlinePlus

Deletion of HAT1 primarily leads to upregulation of genes.(A) Lack of Hat1 causes mainly induction of genes in logarithmically growing cells. Each dot corresponds to one protein-coding gene. The fold change in RNA expression between untreated wild-type and hat1Δ/Δ cells (y-axis) is plotted against the expression level of each gene in this dataset (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logCPM: log2 counts per million reads; logFC: log2 fold change; (B+C) Loss of Cac2 or Rtt109 causes almost exclusively upregulation of genes in logarithmically growing cells. Plots were created as described in (A). (D) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants in the absence of H2O2. (E) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants upon treatment with H2O2. (F) H2O2 repressed genes are upregulated in the hat1Δ/Δ mutant upon peroxide treatment. Each dot corresponds to one protein-coding gene. The -fold change in RNA expression between H2O2 treated wild-type and hat1Δ/Δ strains (y-axis) is plotted against the fold change between the wild-type without and with treatment (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logFC: log2 fold change; (A-F) Differentially regulated genes were defined by a fold change > = 2 and p-value <0.05.
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ppat.1005218.g004: Deletion of HAT1 primarily leads to upregulation of genes.(A) Lack of Hat1 causes mainly induction of genes in logarithmically growing cells. Each dot corresponds to one protein-coding gene. The fold change in RNA expression between untreated wild-type and hat1Δ/Δ cells (y-axis) is plotted against the expression level of each gene in this dataset (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logCPM: log2 counts per million reads; logFC: log2 fold change; (B+C) Loss of Cac2 or Rtt109 causes almost exclusively upregulation of genes in logarithmically growing cells. Plots were created as described in (A). (D) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants in the absence of H2O2. (E) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants upon treatment with H2O2. (F) H2O2 repressed genes are upregulated in the hat1Δ/Δ mutant upon peroxide treatment. Each dot corresponds to one protein-coding gene. The -fold change in RNA expression between H2O2 treated wild-type and hat1Δ/Δ strains (y-axis) is plotted against the fold change between the wild-type without and with treatment (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logFC: log2 fold change; (A-F) Differentially regulated genes were defined by a fold change > = 2 and p-value <0.05.

Mentions: RNA-Seq analysis of logarithmically growing cells showed that genetic removal of HAT1 primarily upregulates a large number of genes. We found 743 genes at least 2-fold induced and 209 genes 2-fold repressed in the hat1Δ/Δ mutant when compared to the wild-type. Furthermore, the amplitude of gene repression was clearly lower when compared to the upregulation of genes, implying that Hat1 exerts primarily repressing rather than activating functions (Fig 4A). Also for the cac2Δ/Δ and rtt109Δ/Δ mutants, we observed an almost exclusive upregulation of gene expression when compared to the wild-type (Fig 4B and 4C). However, lack of Cac2 or Rtt109 had a less pronounced effect concerning the number of upregulated genes when compared to the loss of Hat1. In the cac2Δ/Δ and the rtt109Δ/Δ strains, 464 and 243 genes were transcriptionally upregulated, respectively. Comparison of regulated genes in the hat1Δ/Δ, the cac2Δ/Δ and the rtt109Δ/Δ mutants revealed large overlaps between all datasets (Fig 4D) with 123 genes upregulated in all three mutants. Interestingly, the majority of upregulated genes in the cac2Δ/Δ mutant were also induced in the hat1Δ/Δ strain. As expected, we also detected a large overlap between the hat1Δ/Δ and the rtt109Δ/Δ strain, since both mutants share functions in DNA damage repair and cell morphology [10,30].


The Candida albicans Histone Acetyltransferase Hat1 Regulates Stress Resistance and Virulence via Distinct Chromatin Assembly Pathways.

Tscherner M, Zwolanek F, Je S, Sedlazeck FJ, Petryshyn A, Frohner IE, Mavrianos J, Chauhan N, von Haeseler A, Kuchler K - PLoS Pathog. (2015)

Deletion of HAT1 primarily leads to upregulation of genes.(A) Lack of Hat1 causes mainly induction of genes in logarithmically growing cells. Each dot corresponds to one protein-coding gene. The fold change in RNA expression between untreated wild-type and hat1Δ/Δ cells (y-axis) is plotted against the expression level of each gene in this dataset (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logCPM: log2 counts per million reads; logFC: log2 fold change; (B+C) Loss of Cac2 or Rtt109 causes almost exclusively upregulation of genes in logarithmically growing cells. Plots were created as described in (A). (D) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants in the absence of H2O2. (E) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants upon treatment with H2O2. (F) H2O2 repressed genes are upregulated in the hat1Δ/Δ mutant upon peroxide treatment. Each dot corresponds to one protein-coding gene. The -fold change in RNA expression between H2O2 treated wild-type and hat1Δ/Δ strains (y-axis) is plotted against the fold change between the wild-type without and with treatment (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logFC: log2 fold change; (A-F) Differentially regulated genes were defined by a fold change > = 2 and p-value <0.05.
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ppat.1005218.g004: Deletion of HAT1 primarily leads to upregulation of genes.(A) Lack of Hat1 causes mainly induction of genes in logarithmically growing cells. Each dot corresponds to one protein-coding gene. The fold change in RNA expression between untreated wild-type and hat1Δ/Δ cells (y-axis) is plotted against the expression level of each gene in this dataset (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logCPM: log2 counts per million reads; logFC: log2 fold change; (B+C) Loss of Cac2 or Rtt109 causes almost exclusively upregulation of genes in logarithmically growing cells. Plots were created as described in (A). (D) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants in the absence of H2O2. (E) Venn diagram showing the overlaps of upregulated genes in the hat1Δ/Δ, cac2Δ/Δ and rtt109Δ/Δ mutants upon treatment with H2O2. (F) H2O2 repressed genes are upregulated in the hat1Δ/Δ mutant upon peroxide treatment. Each dot corresponds to one protein-coding gene. The -fold change in RNA expression between H2O2 treated wild-type and hat1Δ/Δ strains (y-axis) is plotted against the fold change between the wild-type without and with treatment (x-axis). Differentially expressed genes in the hat1Δ/Δ mutant are depicted in red. logFC: log2 fold change; (A-F) Differentially regulated genes were defined by a fold change > = 2 and p-value <0.05.
Mentions: RNA-Seq analysis of logarithmically growing cells showed that genetic removal of HAT1 primarily upregulates a large number of genes. We found 743 genes at least 2-fold induced and 209 genes 2-fold repressed in the hat1Δ/Δ mutant when compared to the wild-type. Furthermore, the amplitude of gene repression was clearly lower when compared to the upregulation of genes, implying that Hat1 exerts primarily repressing rather than activating functions (Fig 4A). Also for the cac2Δ/Δ and rtt109Δ/Δ mutants, we observed an almost exclusive upregulation of gene expression when compared to the wild-type (Fig 4B and 4C). However, lack of Cac2 or Rtt109 had a less pronounced effect concerning the number of upregulated genes when compared to the loss of Hat1. In the cac2Δ/Δ and the rtt109Δ/Δ strains, 464 and 243 genes were transcriptionally upregulated, respectively. Comparison of regulated genes in the hat1Δ/Δ, the cac2Δ/Δ and the rtt109Δ/Δ mutants revealed large overlaps between all datasets (Fig 4D) with 123 genes upregulated in all three mutants. Interestingly, the majority of upregulated genes in the cac2Δ/Δ mutant were also induced in the hat1Δ/Δ strain. As expected, we also detected a large overlap between the hat1Δ/Δ and the rtt109Δ/Δ strain, since both mutants share functions in DNA damage repair and cell morphology [10,30].

Bottom Line: Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment.Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade.The reduced azole susceptibility appears to be conserved in a wider range of fungi.

View Article: PubMed Central - PubMed

Affiliation: Department for Medical Biochemistry, Medical University of Vienna, Max F. Perutz Laboratories, Campus Vienna Biocenter, Vienna, Austria.

ABSTRACT
Human fungal pathogens like Candida albicans respond to host immune surveillance by rapidly adapting their transcriptional programs. Chromatin assembly factors are involved in the regulation of stress genes by modulating the histone density at these loci. Here, we report a novel role for the chromatin assembly-associated histone acetyltransferase complex NuB4 in regulating oxidative stress resistance, antifungal drug tolerance and virulence in C. albicans. Strikingly, depletion of the NuB4 catalytic subunit, the histone acetyltransferase Hat1, markedly increases resistance to oxidative stress and tolerance to azole antifungals. Hydrogen peroxide resistance in cells lacking Hat1 results from higher induction rates of oxidative stress gene expression, accompanied by reduced histone density as well as subsequent increased RNA polymerase recruitment. Furthermore, hat1Δ/Δ cells, despite showing growth defects in vitro, display reduced susceptibility to reactive oxygen-mediated killing by innate immune cells. Thus, clearance from infected mice is delayed although cells lacking Hat1 are severely compromised in killing the host. Interestingly, increased oxidative stress resistance and azole tolerance are phenocopied by the loss of histone chaperone complexes CAF-1 and HIR, respectively, suggesting a central role for NuB4 in the delivery of histones destined for chromatin assembly via distinct pathways. Remarkably, the oxidative stress phenotype of hat1Δ/Δ cells is a species-specific trait only found in C. albicans and members of the CTG clade. The reduced azole susceptibility appears to be conserved in a wider range of fungi. Thus, our work demonstrates how highly conserved chromatin assembly pathways can acquire new functions in pathogenic fungi during coevolution with the host.

No MeSH data available.


Related in: MedlinePlus