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Interactions between copy number and expression level of genes involved in fluconazole resistance in Candida glabrata.

Abbes S, Mary C, Sellami H, Michel-Nguyen A, Ayadi A, Ranque S - Front Cell Infect Microbiol (2013)

Bottom Line: The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model.In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs.The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moléculaire Parasitaire et Fongique, Faculté de médecine, University of Sfax Sfax, Tunisie.

ABSTRACT

Objectives: This study aimed to elucidate the relative involvement of drug resistance gene copy number and overexpression in fluconazole resistance in clinical C. glabrata isolates using a population-based approach.

Methods: Fluconazole resistance levels were quantified using the minimal inhibitory concentration (MIC) via Etest method. Both gene expression levels and gene copy number of CgCDR1, CgPDH1, CgERG11, and CgSNQ2 were assessed via quantitative real-time PCR. The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model.

Results: Forty-three C. glabrata isolates were collected from 30 patients during in a hospital survey. In the multivariate analysis, C. glabrata fluconazole MICs were independently increased by CgSNQ2 overexpression (p < 10(-4)) and the interaction between CgPDH1 gene copy number and CgPDH1 expression level (p = 0.038). In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs.

Conclusion: Fluconazole resistance in C. glabrata involves complex interactions between drug resistance gene expression and/or copy number. The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

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Illustration of the effect of the complex interactions between CgPDH1, CgSNQ2, and CgERG11 drug resistance gene copy numbers and expression levels on fluconazole resistance in Candida glabrata clinical isolates. CgPDH1 gene copy number and expression were correlated, and their interaction led to an increase in fluconazole MIC levels. In contrast, the main effect of CgPDH1 overexpression independently led to a decrease in MIC levels. The main effect of CgSNQ2 overexpression independently promoted an increase in fluconazole MIC levels, while its interaction with CgERG11 expression led to a decrease in MIC levels.
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Figure 1: Illustration of the effect of the complex interactions between CgPDH1, CgSNQ2, and CgERG11 drug resistance gene copy numbers and expression levels on fluconazole resistance in Candida glabrata clinical isolates. CgPDH1 gene copy number and expression were correlated, and their interaction led to an increase in fluconazole MIC levels. In contrast, the main effect of CgPDH1 overexpression independently led to a decrease in MIC levels. The main effect of CgSNQ2 overexpression independently promoted an increase in fluconazole MIC levels, while its interaction with CgERG11 expression led to a decrease in MIC levels.

Mentions: Quantitative real-time PCR analysis was performed to measure the expression levels and copy number of each of the four target genes: CgCDR1, CgPDH1, CgSNQ2, and CgERG11 (Table 1). Gene transcript levels and copy number values were normalized to URA3, a single copy gene encoding orotidine 5-phosphate decarboxylase.


Interactions between copy number and expression level of genes involved in fluconazole resistance in Candida glabrata.

Abbes S, Mary C, Sellami H, Michel-Nguyen A, Ayadi A, Ranque S - Front Cell Infect Microbiol (2013)

Illustration of the effect of the complex interactions between CgPDH1, CgSNQ2, and CgERG11 drug resistance gene copy numbers and expression levels on fluconazole resistance in Candida glabrata clinical isolates. CgPDH1 gene copy number and expression were correlated, and their interaction led to an increase in fluconazole MIC levels. In contrast, the main effect of CgPDH1 overexpression independently led to a decrease in MIC levels. The main effect of CgSNQ2 overexpression independently promoted an increase in fluconazole MIC levels, while its interaction with CgERG11 expression led to a decrease in MIC levels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3822285&req=5

Figure 1: Illustration of the effect of the complex interactions between CgPDH1, CgSNQ2, and CgERG11 drug resistance gene copy numbers and expression levels on fluconazole resistance in Candida glabrata clinical isolates. CgPDH1 gene copy number and expression were correlated, and their interaction led to an increase in fluconazole MIC levels. In contrast, the main effect of CgPDH1 overexpression independently led to a decrease in MIC levels. The main effect of CgSNQ2 overexpression independently promoted an increase in fluconazole MIC levels, while its interaction with CgERG11 expression led to a decrease in MIC levels.
Mentions: Quantitative real-time PCR analysis was performed to measure the expression levels and copy number of each of the four target genes: CgCDR1, CgPDH1, CgSNQ2, and CgERG11 (Table 1). Gene transcript levels and copy number values were normalized to URA3, a single copy gene encoding orotidine 5-phosphate decarboxylase.

Bottom Line: The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model.In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs.The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire de Biologie Moléculaire Parasitaire et Fongique, Faculté de médecine, University of Sfax Sfax, Tunisie.

ABSTRACT

Objectives: This study aimed to elucidate the relative involvement of drug resistance gene copy number and overexpression in fluconazole resistance in clinical C. glabrata isolates using a population-based approach.

Methods: Fluconazole resistance levels were quantified using the minimal inhibitory concentration (MIC) via Etest method. Both gene expression levels and gene copy number of CgCDR1, CgPDH1, CgERG11, and CgSNQ2 were assessed via quantitative real-time PCR. The influence of the main effects and first-level interactions of both the expression level and copy number of these genes on fluconazole resistance levels were analyzed using a multivariate statistical model.

Results: Forty-three C. glabrata isolates were collected from 30 patients during in a hospital survey. In the multivariate analysis, C. glabrata fluconazole MICs were independently increased by CgSNQ2 overexpression (p < 10(-4)) and the interaction between CgPDH1 gene copy number and CgPDH1 expression level (p = 0.038). In contrast, both CgPDH1 overexpression (p = 0.049) and the interaction between CgSNQ2 and CgERG11 expression (p = 0.003) led to a significant decrease in fluconazole MICs.

Conclusion: Fluconazole resistance in C. glabrata involves complex interactions between drug resistance gene expression and/or copy number. The population-based multivariate analysis highlighted the involvement of the CgSNQ2 gene in fluconazole resistance and the complex effect of the other genes such as PDH1 for which overexpression was associated with reduced fluconazole resistance levels, while the interaction between PDH1 overexpression and copy number was associated with increased resistance levels.

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