Cryptococcus neoformans can form titan-like cells in vitro in response to multiple signals

• Published in: PLoS pathogens Vol. 14; no. 5; p. e1007007
• Main Authors: Trevijano-Contador, Nuria, de Oliveira, Haroldo Cesar, García-Rodas, Rocío, Rossi, Suélen Andreia, Llorente, Irene, Zaballos, Ángel, Janbon, Guilhem, Ariño, Joaquín, Zaragoza, Óscar
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 18.05.2018; Public Library of Science (PLoS)
• Subjects: Adaptation; Animals; Biology and Life Sciences; Body size; Calnexin; Carbohydrate metabolism; Carbohydrates; Carbon dioxide; Cell body; Cell size; Cellular signal transduction; Cryptococcosis / microbiology; Cryptococcus; Cryptococcus neoformans; Cryptococcus neoformans / cytology; Cryptococcus neoformans / genetics; Cryptococcus neoformans / pathogenicity; Earth Sciences; Ecology and Environmental Sciences; Enlargement; Expansion; Experimentation; Fungal infections; Gene expression; Gene Expression Profiling; Genes, Fungal; Genetic aspects; Genotypes; Health aspects; Host-Pathogen Interactions / genetics; Host-Pathogen Interactions / physiology; Humans; Incubation; Infections; Infectious diseases; Iron; Laboratories; Life Sciences; Macrophages / microbiology; Male; Medicine and Health Sciences; Metabolism; Mice; Mice, Inbred C57BL; Microbiology and Parasitology; Models, Biological; Molecular chains; Mycology; Pathogens; Phagocytosis; Pharmacology; Phenotype; Physical Sciences; Protein kinase C; Proteins; Quorum Sensing; RAW 264.7 Cells; Saturn satellites; Signal Transduction; Titan; Virulence (Microbiology); Yeast; Spain; Cell formation; Physiological parameters; Cryptococcus neoformans; Carbon dioxide; Cryptococcus; Macrophages; Gene expression; Phagocytosis
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1007007

Cryptococcus neoformans is an encapsulated pathogenic yeast that can change the size of the cells during infection. In particular, this process can occur by enlarging the size of the capsule without modifying the size of the cell body, or by increasing the diameter of the cell body, which is normally accompanied by an increase of the capsule too. This last process leads to the formation of cells of an abnormal enlarged size denominated titan cells. Previous works characterized titan cell formation during pulmonary infection but research on this topic has been hampered due to the difficulty to obtain them in vitro. In this work, we describe in vitro conditions (low nutrient, serum supplemented medium at neutral pH) that promote the transition from regular to titan-like cells. Moreover, addition of azide and static incubation of the cultures in a CO2 enriched atmosphere favored cellular enlargement. This transition occurred at low cell densities, suggesting that the process was regulated by quorum sensing molecules and it was independent of the cryptococcal serotype/species. Transition to titan-like cell was impaired by pharmacological inhibition of PKC signaling pathway. Analysis of the gene expression profile during the transition to titan-like cells showed overexpression of enzymes involved in carbohydrate metabolism, as well as proteins from the coatomer complex, and related to iron metabolism. Indeed, we observed that iron limitation also induced the formation of titan cells. Our gene expression analysis also revealed other elements involved in titan cell formation, such as calnexin, whose absence resulted in appearance of abnormal large cells even in regular rich media. In summary, our work provides a new alternative method to investigate titan cell formation devoid the bioethical problems that involve animal experimentation.