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Updated: May 3, 2026
Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans
Published on: March 19, 2015
Glucosylceramide synthase is an essential regulator of pathogenicity of Cryptococcus neoformans
Philipp C Rittershaus1, Talar B Kechichian, Jeremy C Allegood
1Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
Abstract:
The pathogenic fungus Cryptococcus neoformans infects humans upon inhalation and causes the most common fungal meningoencephalitis in immunocompromised subjects worldwide. In the host, C. neoformans is found both intracellularly and extracellularly, but how these two components contribute to the development of the disease is largely unknown. Here we show that the glycosphingolipid glucosylceramide (GlcCer), which is present in C. neoformans, was essential for fungal growth in host extracellular environments, such as in alveolar spaces and in the bloodstream, which are characterized by a neutral/alkaline pH, but not in the host intracellular environment, such as in the phagolysosome of macrophages, which is characteristically acidic. Indeed, a C. neoformans mutant strain lacking GlcCer did not grow in vitro at a neutral/alkaline pH, yet it had no growth defect at an acidic pH. The mechanism by which GlcCer regulates alkali tolerance was by allowing the transition of C. neoformans through the cell cycle. This study establishes C. neoformans GlcCer as a key virulence factor of cryptococcal pathogenicity, with important implications for future development of new antifungal strategies.
Insights
The fungal pathogen Cryptococcus neoformans requires glucosylceramide (GlcCer) for growth in alkaline host environments, impacting its virulence. This finding offers new avenues for antifungal drug development.
Area of Science:
- Mycology
- Infectious Diseases
- Pathogenesis
Background:
- Cryptococcus neoformans causes fungal meningoencephalitis, particularly in immunocompromised individuals.
- The fungus exists intracellularly and extracellularly, but the roles of these locations in disease are unclear.
Purpose of the Study:
- To investigate the role of glucosylceramide (GlcCer) in Cryptococcus neoformans virulence.
- To understand how GlcCer affects fungal survival in different host environments.
Main Methods:
- Culturing a C. neoformans mutant strain lacking GlcCer.
- Assessing fungal growth at varying pH levels (acidic vs. neutral/alkaline) in vitro.
- Analyzing the effect of GlcCer on fungal cell cycle progression.
Main Results:
- GlcCer is essential for C. neoformans growth in neutral/alkaline pH environments, mimicking extracellular spaces.
- A C. neoformans mutant lacking GlcCer failed to grow at neutral/alkaline pH but showed no defect at acidic pH.
- GlcCer facilitates alkali tolerance by enabling cell cycle transition.
Conclusions:
- Cryptococcus neoformans glucosylceramide (GlcCer) is a critical virulence factor.
- GlcCer's role in alkali tolerance is key to cryptococcal pathogenicity.
- Targeting GlcCer may lead to novel antifungal strategies.
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