The upregulation of the multidrug-transporter genes CDR1 and CDR2 (Candida Drug Resistance) and CaMDR1 (Candida albicans Multidrug Resistance) is an important strategy used by the human pathogen C. albicans to resist against antifungal agents and especially against the class of azole antifungals. CDR1, CDR2 and CaMDR1 can be specifically induced by treating cells in vitro with different drugs such as oestradiol and fluphenazine for CDR1 and CDR2 or benomyl and H2O2 for CaMDR1. This property provides a powerful tool in the study of the molecular basis of multidrug transporter genes upregulation. In order to determine elements involved in their regulatory pathway, we used a genome-wide approach based on DNA microarray technology. In this study, total RNA from fluphenazine- and benomyl-treated and non-treated cells were spotted on Eurogentec DNA microarrays (from Candida albicans SC5314). As the two drugs activate specifically CDR1 and CDR2 and CaMDR1, we determined if other genes were significantly regulated by each drug. In the case of fluphenazine, 21 and 28 out of 5855 genes were up- and downregulated, respectively. We previously showed that fluphenazine acts on CDR1 and CDR2 genes through a Drug Responsive Element (DRE) present in both promoters. We found 10 genes containing such a sequence in their promoter when analysing the entire C. albicans genome. Among the 21 fluphenazine upregulated genes, only 3 (CDR1, CDR2 and IFU5) contained a perfect DRE. Nevertheless theses genes are the most strongly upregulated, showing a crucial role of the DRE. When using benomyl, 50 and 25 out of 5855 genes were up- and downregulated, respectively. Only 5 genes appeared to be commonly regulated by both drugs (HYR1, GRP2, IFD4, YDR533c, upregulated and FTR2 downregulated). Therefore, both drugs seem to activate different upregulation pathways. As H2O2 allows the activation of CaMDR1 as benomyl does, we compared our results with published C. albicans microarray data of M. Whiteway on cells exposed to H2O2. Out of 534 genes significantly modulated by both compounds, 11 genes were commonly upregulated and, among them, 3 (TRX1, TTR1, TRR1) are typical for oxidative stress response. Therefore, benomyl exposure can only partially overlap with an oxidative stress response. The transcript profiles obtained here will be helpful in comparison to those obtained with azole-resistant strains subjected to microarray analysis.
Full conference title:
The 15 th Congress of the International Society for Human and Animal Mycology
- ISHAM 15th (2003)