Abstract
Pathogenic basidiomycetous yeast, Cryptococcus neoformans, causes fatal meningitis in immunocompromised individuals. Fluconazole (FLC) is a fungistatic drug commonly administered to treat cryptococcosis. Unfortunately, FLC-resistant strains characterized by various degree of chromosomal instability were isolated from clinical patients. Importantly, the underlying mechanisms that lead to chromosomal instability in FLC-treated C. neoformans remain elusive. Previous studies in fungal and mammalian cells link chromosomal instability to the reactive oxygen species (ROS). This study provides the evidence that exposure of C. neoformans to FLC induces accumulation of intracellular ROS, which correlates with plasma membrane damage. FLC caused transcription changes of oxidative stress related genes encoding superoxide dismutase (SOD1), catalase (CAT3), and thioredoxin reductase (TRR1). Strikingly, FLC contributed to an increase of the DNA damage in vitro, when complexed with iron or copper in the presence of hydrogen peroxide. Strains with isogenic deletion of copper response protein metallothionein were more susceptible to FLC. Addition of ascorbic acid (AA), an anti-oxidant at 10 mM, reduced the inhibitory effects of FLC. Consistent with potential effects of FLC on DNA integrity and chromosomal segregation, FLC treatment led to elevated transcription of RAD54 and repression of cohesin-encoding gene SCC1. We propose that FLC forms complexes with metals and contributes to elevated ROS, which may lead to chromosomal instability in C. neoformans.
Highlights
Cryptococcus neoformans is a basidiomycetous yeast that causes pneumonia and meningitis primarily in immunocompromised patients, rendering approximately 620,000 deaths per year [1,2,3]
We demonstrate an increase of intracellular chronic oxidative stress in FLC-treated C. neoformans and enhanced DNA damage by FLC in complex with redox active iron or copper in vitro
The same study showed that C. tropicalis strains resistant to FLC did not exhibit a spike of intracellular reactive oxygen species (ROS) when subsequently treated with FLC
Summary
Cryptococcus neoformans is a basidiomycetous yeast that causes pneumonia and meningitis primarily in immunocompromised patients, rendering approximately 620,000 deaths per year [1,2,3]. Global prevalence of cryptococcal disease is 5–10% in Americas and Europe, and exceeds 15% in South East Asia and Sub-Saharan Africa [4, 5]. ROS-dependent fluconazole resistance of Cryptococcus tolerated triazole drug that accumulates in the cerebrospinal fluid is often chosen to initiate treatment of cryptococcal meningitis or as a maintenance therapy [6, 7]. Due to the fungistatic effect of FLC, the emergence of resistance to the drug complicates treatments [8,9,10]. There is a need to develop more effective therapies and towards this goal demarcate mechanisms for drug resistance
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
