title: Extrusion of fluorescein diacetate by multidrug-resistant Candida albicans.
abstract: Over-expression of multidrug efflux transporters causes Candida albicans cells to be resistant to azole antifungal agents. There are several kinds of indicator for multidrug resistance (MDR) phenotype of higher eukaryotic cells. Calcein AM is a prefluorochrome that is known as a substrate for multidrug efflux transporters of mammalian cells. We investigated whether calcein AM was also extruded by the ATP-dependent multidrug transporter (cdr1p) of C. albicans. There was no significant difference in the accumulation of calcein AM between MDR cells and drug-susceptible cells of C. albicans even with sodium azide, suggesting that calcein AM may not be associated with the CDR1-gene-related multidrug efflux system of C. albicans. However, a structurally related prefluorochrome derivative, fluorescein diacetate (FDA), was shown to be extruded by the CDR1 mRNA-overexpressing yeast cells. In comparison with drug-susceptible cells, the resistant cells emitted very weak fluorescence when stained with FDA. Furthermore sodium azide increased the fluorescence of the resistant cells more than 20 times, whereas the fluorescence in the drug-susceptible cells with FDA and sodium azide was three to four times stronger. These results suggested that FDA might be extruded by the CDR1-related multidrug efflux transporter of C. albicans.
authors.affiliation: Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Japan.
authors.forename: H C
authors.initials: HC
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Mikami
authors.forename: T
authors.initials: T
authors.lastname: Imai
authors.forename: H
authors.initials: H
authors.lastname: Taguchi
authors.forename: K
authors.initials: K
authors.lastname: Nishimura
authors.forename: M
authors.initials: M
authors.lastname: Miyaji
authors.forename: M L
authors.initials: ML
authors.lastname: Branchini
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D026141:Drug Resistance, Multiple, Fungal; D005434:Flow Cytometry; D005452:Fluoresceins / Q000032:analysis*; D005456:Fluorescent Dyes / Q000032:analysis*; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins
chemical_list: D000935:Antifungal Agents; D001393:Azoles; D005452:Fluoresceins; D005456:Fluorescent Dyes; D029702:Schizosaccharomyces pombe Proteins; C085925:calcein AM; C080364:cdr1 protein, S pombe; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C018506:diacetylfluorescein