title: DNA microarray analysis of fluconazole resistance in a laboratory Candida albicans strain.
abstract: Several mechanisms are responsible for the acquired fluconazole (FLC) resistance in Candida albicans. In this study, we developed a FLC-resistant C. albicans strain through serial cultures of a FLC-susceptible C. albicans strain with inhibitory concentrations of FLC. Complimentary DNA microarray analysis and real-time reverse transcription-polymerase chain reaction were used to investigate gene expression changes during the acquisition of azole resistance in the susceptible parental strain and the resistant daughter strain. The differentially expressed genes represented functions as diverse as transporters (e.g. CDR1, PDR17), ergosterol biosynthesis (e.g. ERG2, ERG9), sterol metabolism (e.g. ARE2, IPF6464), energy metabolism (e.g. ADH3, AOX2) and transcription factors (e.g. FCR1, ECM22). Functional analysis revealed that energy-dependent efflux activity of membrane transporters increased and that ergosterol content decreased with the accumulation of sterol intermediates in the resistant strain as compared with the susceptible strain. We found that a point mutation (N977K) in transcription factor TAC1 that resulted in hyperactivity of Tac1 could be the reason for overexpression of CDR1, CDR2, and PDR17 in the resistant strain. Furthermore, a single amino acid difference (D19E) in ERG3 that led to the inactivation of Erg3 could account for both sterol precursor accumulation and the changes in the expression of ergosterol biosynthesis genes in this resistant strain. These findings expand the understanding of potential novel molecular targets of FLC resistance in clinical C. albicans isolates.
authors.affiliation: Department of Pharmacology, College of Pharmacy, Second Military Medical University, Shanghai, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Yan
authors.forename: Jundong
authors.initials: J
authors.lastname: Zhang
authors.forename: Miaohai
authors.initials: M
authors.lastname: Li
authors.forename: Yongbing
authors.initials: Y
authors.lastname: Cao
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xu
authors.forename: Yingying
authors.initials: Y
authors.lastname: Cao
authors.forename: Pinghui
authors.initials: P
authors.lastname: Gao
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Yuanying
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001483:Base Sequence; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics; D017931:DNA Primers; D015725:Fluconazole / Q000494:pharmacology*; D005800:Genes, Fungal; D020411:Oligonucleotide Array Sequence Analysis; D017354:Point Mutation; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000935:Antifungal Agents; D017931:DNA Primers; D015725:Fluconazole