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Published on: June 13, 2021
The cell wall protein Rhd3/Pga29 is over-expressed in Candida albicans upon micafungin treatment
Abstract:
Candida albicans cell wall constitutes a sensitive boundary that undergoes molecular changes upon environmental injuries. Antimycotics exert an intense action on cell wall eliciting both qualitative and quantitative changes of resident proteins. The emergence of drug resistance is marked by a modulation of cell wall proteomic profile. In this study, we monitored, at the proteome level through a two-dimensional gel electrophoresis-based approach, differences of cell wall proteins in sensitive and resistant strains of C. albicans, and variations occurring upon treatment of these strains with antifungal drugs. We identified Rhd3/Pga29, a glycophosphatidylinositol (GPI)-anchored protein, as the main over-expressed protein in micafungin resistant strain with respect to the sensitive control cells. A further increase of Rhd3/Pga29 took place when these resistant strains were treated with sub-lethal dose of micafungin. These results were also confirmed in other two clinical isolates resistant to caspofungin. Results were validated by Western blot analyses and RT-PCR and immunoelectron microscopy images confirmed the increase of the Rhd3/Pga29 on the cell wall as well as in the cytosolic compartment of the micafungin-treated resistant cells. Rhd3/Pga29 over-expression upon echinocandin treatment could represent a strategy of C. albicans to counteract the toxic action of this drug. A role of this protein has also been claimed in the virulence of the fungus, suggesting an involvement of Rhd3/Pga29 in the relationship between C. albicans and the host.
Insights
Candida albicans develops drug resistance through changes in its cell wall proteome. Rhd3/Pga29 protein is significantly over-expressed in resistant strains, especially after antifungal treatment, indicating a potential resistance mechanism.
Area of Science:
- Mycology
- Molecular Biology
- Proteomics
Background:
- The cell wall of Candida albicans is dynamic and changes in response to environmental stress and antifungal drugs.
- Antifungal drug resistance in C. albicans is associated with alterations in the cell wall's protein composition.
- Understanding these proteomic changes is crucial for developing new antifungal strategies.
Purpose of the Study:
- To investigate the proteomic differences in the cell wall of drug-sensitive and drug-resistant Candida albicans strains.
- To analyze how antifungal drug treatment affects the cell wall proteome of C. albicans.
- To identify key proteins involved in echinocandin resistance.
Main Methods:
- Two-dimensional gel electrophoresis-based proteomic analysis.
- Western blot analysis for protein validation.
- RT-PCR to assess gene expression levels.
- Immunoelectron microscopy to visualize protein localization.
Main Results:
- Rhd3/Pga29, a GPI-anchored protein, was identified as significantly over-expressed in micafungin-resistant C. albicans strains compared to sensitive strains.
- Treatment of resistant strains with sub-lethal doses of micafungin led to a further increase in Rhd3/Pga29 levels.
- Similar Rhd3/Pga29 over-expression was observed in clinical isolates resistant to caspofungin.
- Immunoelectron microscopy confirmed increased Rhd3/Pga29 in the cell wall and cytoplasm of treated resistant cells.
Conclusions:
- Over-expression of Rhd3/Pga29 may be a key mechanism by which Candida albicans counteracts the effects of echinocandin antifungal drugs.
- Rhd3/Pga29's known role in virulence suggests it could be involved in the interaction between C. albicans and the host, potentially linking drug resistance and pathogenicity.
