Limits...
Microevolution of Candida albicans in macrophages restores filamentation in a nonfilamentous mutant.

Wartenberg A, Linde J, Martin R, Schreiner M, Horn F, Jacobsen ID, Je S, Wolf T, Kuchler K, Guthke R, Kurzai O, Forche A, d'Enfert C, Brunke S, Hube B - PLoS Genet. (2014)

Bottom Line: In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation.We went on to identify the causative missense mutation via whole genome- and transcriptome-sequencing: a single nucleotide exchange took place within SSN3 that encodes a component of the Cdk8 module of the Mediator complex, which links transcription factors with the general transcription machinery.These data demonstrate that even central transcriptional networks can be remodeled very quickly under appropriate selection pressure.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute Jena (HKI), Jena, Germany.

ABSTRACT
Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo microevolution, which leads to the emergence of drug resistance. However, the capacity for microevolutionary adaptation of fungi goes beyond the development of resistance against antifungals. Here we used an experimental microevolution approach to show that one of the central pathogenicity mechanisms of C. albicans, the yeast-to-hyphae transition, can be subject to experimental evolution. The C. albicans cph1Δ/efg1Δ mutant is nonfilamentous, as central signaling pathways linking environmental cues to hyphal formation are disrupted. We subjected this mutant to constant selection pressure in the hostile environment of the macrophage phagosome. In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation. In addition, the evolved mutant exhibited hyper-virulence in a murine infection model and an altered cell wall composition compared to the cph1Δ/efg1Δ strain. Moreover, the transcriptional regulation of hyphae-associated, and other pathogenicity-related genes became re-responsive to environmental cues in the evolved strain. We went on to identify the causative missense mutation via whole genome- and transcriptome-sequencing: a single nucleotide exchange took place within SSN3 that encodes a component of the Cdk8 module of the Mediator complex, which links transcription factors with the general transcription machinery. This mutation was responsible for the reconnection of the hyphal growth program with environmental signals in the evolved strain and was sufficient to bypass Efg1/Cph1-dependent filamentation. These data demonstrate that even central transcriptional networks can be remodeled very quickly under appropriate selection pressure.

No MeSH data available.


Related in: MedlinePlus

Expression of transcription factors under filament-inducing conditions.(A+B) Relative expression of nine central transcription factor genes in the analyzed strains after growth in DMEM+10% FBS at 37°C and 5% CO2 on a plastic surface. Fold change between filament-inducing and yeast promoting conditions (YPD, 30°C) is shown, normalized to three housekeeping genes (ACT1, EFB1 and PMA1). Means+SD of n = 3 (dotted line indicates threshold at 1.5; *p<0.05). (C) Deletion of EFH1 in the Evo strain did not affect hyphal growth. Cells were incubated for 18 h at 37°C and 5% CO2 in DMEM+10% FBS (representative pictures).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4256171&req=5

pgen-1004824-g004: Expression of transcription factors under filament-inducing conditions.(A+B) Relative expression of nine central transcription factor genes in the analyzed strains after growth in DMEM+10% FBS at 37°C and 5% CO2 on a plastic surface. Fold change between filament-inducing and yeast promoting conditions (YPD, 30°C) is shown, normalized to three housekeeping genes (ACT1, EFB1 and PMA1). Means+SD of n = 3 (dotted line indicates threshold at 1.5; *p<0.05). (C) Deletion of EFH1 in the Evo strain did not affect hyphal growth. Cells were incubated for 18 h at 37°C and 5% CO2 in DMEM+10% FBS (representative pictures).

Mentions: The yeast-to-filament regulatory network comprises many different transcription factors (TFs). The filament-associated biofilm formation is controlled by a network formed by Bcr1, Tec1, Brg1, Rob1, Ndt80 and Efg1 [29]. Efg1 positively regulates all other TF genes in this network except ROB1. We measured the transcription of these central TF genes at 30 min and 60 min after filament induction. As shown in Fig. 4A, we found an at least 1.5-fold upregulation of ROB1 and TEC1 after 30 min, and of BCR1 and BRG1 at both timepoints in the Evo strain. The wild type, however, showed only an increased expression of TEC1 at both timepoints and of BRG1 after 30 min. In contrast, most of these TF genes were down- or scarcely upregulated in the cph1Δ/efg1Δ strain (Fig. 4A).


Microevolution of Candida albicans in macrophages restores filamentation in a nonfilamentous mutant.

Wartenberg A, Linde J, Martin R, Schreiner M, Horn F, Jacobsen ID, Je S, Wolf T, Kuchler K, Guthke R, Kurzai O, Forche A, d'Enfert C, Brunke S, Hube B - PLoS Genet. (2014)

Expression of transcription factors under filament-inducing conditions.(A+B) Relative expression of nine central transcription factor genes in the analyzed strains after growth in DMEM+10% FBS at 37°C and 5% CO2 on a plastic surface. Fold change between filament-inducing and yeast promoting conditions (YPD, 30°C) is shown, normalized to three housekeeping genes (ACT1, EFB1 and PMA1). Means+SD of n = 3 (dotted line indicates threshold at 1.5; *p<0.05). (C) Deletion of EFH1 in the Evo strain did not affect hyphal growth. Cells were incubated for 18 h at 37°C and 5% CO2 in DMEM+10% FBS (representative pictures).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4256171&req=5

pgen-1004824-g004: Expression of transcription factors under filament-inducing conditions.(A+B) Relative expression of nine central transcription factor genes in the analyzed strains after growth in DMEM+10% FBS at 37°C and 5% CO2 on a plastic surface. Fold change between filament-inducing and yeast promoting conditions (YPD, 30°C) is shown, normalized to three housekeeping genes (ACT1, EFB1 and PMA1). Means+SD of n = 3 (dotted line indicates threshold at 1.5; *p<0.05). (C) Deletion of EFH1 in the Evo strain did not affect hyphal growth. Cells were incubated for 18 h at 37°C and 5% CO2 in DMEM+10% FBS (representative pictures).
Mentions: The yeast-to-filament regulatory network comprises many different transcription factors (TFs). The filament-associated biofilm formation is controlled by a network formed by Bcr1, Tec1, Brg1, Rob1, Ndt80 and Efg1 [29]. Efg1 positively regulates all other TF genes in this network except ROB1. We measured the transcription of these central TF genes at 30 min and 60 min after filament induction. As shown in Fig. 4A, we found an at least 1.5-fold upregulation of ROB1 and TEC1 after 30 min, and of BCR1 and BRG1 at both timepoints in the Evo strain. The wild type, however, showed only an increased expression of TEC1 at both timepoints and of BRG1 after 30 min. In contrast, most of these TF genes were down- or scarcely upregulated in the cph1Δ/efg1Δ strain (Fig. 4A).

Bottom Line: In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation.We went on to identify the causative missense mutation via whole genome- and transcriptome-sequencing: a single nucleotide exchange took place within SSN3 that encodes a component of the Cdk8 module of the Mediator complex, which links transcription factors with the general transcription machinery.These data demonstrate that even central transcriptional networks can be remodeled very quickly under appropriate selection pressure.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knoell Institute Jena (HKI), Jena, Germany.

ABSTRACT
Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo microevolution, which leads to the emergence of drug resistance. However, the capacity for microevolutionary adaptation of fungi goes beyond the development of resistance against antifungals. Here we used an experimental microevolution approach to show that one of the central pathogenicity mechanisms of C. albicans, the yeast-to-hyphae transition, can be subject to experimental evolution. The C. albicans cph1Δ/efg1Δ mutant is nonfilamentous, as central signaling pathways linking environmental cues to hyphal formation are disrupted. We subjected this mutant to constant selection pressure in the hostile environment of the macrophage phagosome. In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation. In addition, the evolved mutant exhibited hyper-virulence in a murine infection model and an altered cell wall composition compared to the cph1Δ/efg1Δ strain. Moreover, the transcriptional regulation of hyphae-associated, and other pathogenicity-related genes became re-responsive to environmental cues in the evolved strain. We went on to identify the causative missense mutation via whole genome- and transcriptome-sequencing: a single nucleotide exchange took place within SSN3 that encodes a component of the Cdk8 module of the Mediator complex, which links transcription factors with the general transcription machinery. This mutation was responsible for the reconnection of the hyphal growth program with environmental signals in the evolved strain and was sufficient to bypass Efg1/Cph1-dependent filamentation. These data demonstrate that even central transcriptional networks can be remodeled very quickly under appropriate selection pressure.

No MeSH data available.


Related in: MedlinePlus