Genomic Profiling of the Response of Candida albicans to Itraconazole Treatment Using a DNA Microarray

Abstract

The application of genome-wide expression profiling to determine how drugs achieve their therapeutic effect has provided the pharmaceutical industry with an exciting new tool for drug mode-of-action studies. We used DNA chip technology to study cellular responses to perturbations of ergosterol biosynthesis caused by the broad-spectrum antifungal agent itraconazole. Simultaneous examination of over 6,600 Candida albicans gene transcript levels, representing the entire genome, upon treatment of cells with 10 M itraconazole revealed that 296 genes were responsive. For 116 genes transcript levels were decreased at least 2.5-fold, while for 180 transcript levels were similarly increased. A global upregulation of ERG genes in response to azole treatment was observed. ERG11 and ERG5 were found to be upregulated approximately 12-fold. In addition, a significant upregulation was observed for ERG6, ERG1, ERG3, ERG4, ERG10, ERG9, ERG26, ERG25, ERG2, IDII, HMGS, NCP1, and FEN2, all of which are genes known to be involved in ergosterol biosynthesis. The effects of itraconazole on a wide variety of known metabolic processes are discussed. As over 140 proteins with unknown function were responsive to itraconazole, our analysis might provide-in combination with phenotypic datafirst hints of their potential function. The present report is the first to describe the application of DNA chip technology to study the response of a major human fungal pathogen to drug treatment.

Population genomics of drug resistance in Candida albicans

“…In contrast with other studies that have profiled the response of yeast cells to short-term exposure to azole drugs (14,15), our results do not implicate genes in the ergosterol biosynthesis pathway as major players. The only genes in the ergosterol biosynthesis pathway that were significantly modulated in our experimental populations were ERG1, ERG3, ERG11, and ERG13; the gene with the largest change in expression was ERG1, which was repressed 2.9-fold in D12-260 (see Table 4).…”

“…In the present study, we measured changes in genome-wide gene expression in these evolved populations relative to their common ancestor by using DNA microarrays. In contrast to other microarray-based studies of gene expression in yeasts that have focused on the immediate effects of development (12), regulators (13), antifungal drugs (14,15), and stressful conditions (16), our interest was in the changes in gene expression that became established during adaptation and persisted in the absence of the drug. The drug resistance phenotypes were stable during 50 generations in the absence of drug (10), reflecting genetic change rather than transient physiological response to exposure to the drug.…”

2-Amino-nonyl-6-methoxyl-tetralin muriate inhibits sterol C-14 reductase in the ergosterol biosynthetic pathway

“…To further investigate cellular responses to perturbation of ergosterol biosynthesis stimulated by 10b, we detected the expression of sterol metabolism genes by real-time RT-PCR analyses. The results revealed a global upregulation of sterol metabolism genes, including gene ERG24, ERG5, and ERG11, which is consistent with previous reports [22,23] . This was presumed as a result of feedback control [24] .…”

Budding off: bringing functional genomics toCandida albicans

“…Transcriptional profiling of C. albicans Custom microarrays were initially used to assay expression of select gene subsets following preliminary characterization of the C. albicans genome [91][92][93]. Completion of the genome sequence subsequently enabled global analysis of gene expression [94,95], including the use of high-resolution tiling arrays to assay genome-wide transcription and identify noncoding RNAs and antisense transcripts [96].…”