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Updated: Jun 22, 2025
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Published on: December 28, 2017
Aneuploidy underlies brefeldin A-induced antifungal drug resistance in Cryptococcus neoformans
Zhi-Hui Zhang1, Liu-Liu Sun2, Bu-Qing Fu3
1Institute of Vascular Disease, Shanghai TCM-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Abstract:
Cryptococcus neoformans is at the top of the list of "most wanted" human pathogens. Only three classes of antifungal drugs are available for the treatment of cryptococcosis. Studies on antifungal resistance mechanisms are limited to the investigation of how a particular antifungal drug induces resistance to a particular drug, and the impact of stresses other than antifungals on the development of antifungal resistance and even cross-resistance is largely unexplored. The endoplasmic reticulum (ER) is a ubiquitous subcellular organelle of eukaryotic cells. Brefeldin A (BFA) is a widely used chemical inducer of ER stress. Here, we found that both weak and strong selection by BFA caused aneuploidy formation in C. neoformans, mainly disomy of chromosome 1, chromosome 3, and chromosome 7. Disomy of chromosome 1 conferred cross-resistance to two classes of antifungal drugs: fluconazole and 5-flucytosine, as well as hypersensitivity to amphotericin B. However, drug resistance was unstable, due to the intrinsic instability of aneuploidy. We found overexpression of AFR1 on Chr1 and GEA2 on Chr3 phenocopied BFA resistance conferred by chromosome disomy. Overexpression of AFR1 also caused resistance to fluconazole and hypersensitivity to amphotericin B. Furthermore, a strain with a deletion of AFR1 failed to form chromosome 1 disomy upon BFA treatment. Transcriptome analysis indicated that chromosome 1 disomy simultaneously upregulated AFR1, ERG11, and other efflux and ERG genes. Thus, we posit that BFA has the potential to drive the rapid development of drug resistance and even cross-resistance in C. neoformans, with genome plasticity as the accomplice.
Insights
Brefeldin A (BFA) induces aneuploidy in Cryptococcus neoformans, leading to antifungal cross-resistance. This drug resistance is linked to chromosome 1 disomy and AFR1 gene overexpression, highlighting genome plasticity
Area of Science:
- Mycology
- Genetics
- Drug Resistance
Background:
- Cryptococcus neoformans is a major human pathogen with limited treatment options.
- Antifungal resistance mechanisms, especially those induced by non-antifungal stresses, are poorly understood.
- The endoplasmic reticulum (ER) and its stress responses are crucial in eukaryotic cells.
Purpose of the Study:
- To investigate the impact of endoplasmic reticulum (ER) stress induced by Brefeldin A (BFA) on antifungal resistance in Cryptococcus neoformans.
- To explore the role of aneuploidy and specific genes in mediating drug resistance and cross-resistance.
Main Methods:
- Treatment of Cryptococcus neoformans with Brefeldin A (BFA) under weak and strong selection.
- Analysis of aneuploidy formation, focusing on chromosome disomies.
- Gene expression analysis (transcriptome) and gene deletion/overexpression studies.
- Phenotypic testing for antifungal resistance and hypersensitivity.
Main Results:
- BFA treatment induced aneuploidy, primarily disomy of chromosomes 1, 3, and 7.
- Chromosome 1 disomy conferred cross-resistance to fluconazole and 5-flucytosine, and hypersensitivity to amphotericin B.
- Overexpression of AFR1 (on chromosome 1) and GEA2 (on chromosome 3) mimicked BFA-induced resistance.
- AFR1 deletion prevented BFA-induced chromosome 1 disomy.
Conclusions:
- Brefeldin A can drive rapid development of antifungal drug resistance and cross-resistance in Cryptococcus neoformans.
- Genome plasticity, specifically aneuploidy and genes like AFR1, plays a key role in mediating this resistance.
- Understanding these mechanisms is crucial for developing new strategies against cryptococcosis.
