Cryptococcus neoformans Kin1 protein kinase homologue, identified through a Caenorhabditis elegans screen, promotes virulence in mammals

• Published in: Molecular microbiology 2004-10, Vol.54 (2), p.407-419
• Main Authors: Mylonakis, Eleftherios, Idnurm, Alexander, Moreno, Roberto, El Khoury, Joseph, Rottman, James B., Ausubel, Frederick M., Heitman, Joseph, Calderwood, Stephen B.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological Assay - methods; Brain - microbiology; Brain - pathology; Caenorhabditis elegans; Caenorhabditis elegans - metabolism; Caenorhabditis elegans - microbiology; Cells, Cultured; Cryptococcosis - pathology; Cryptococcus neoformans; Cryptococcus neoformans - enzymology; Cryptococcus neoformans - genetics; Cryptococcus neoformans - pathogenicity; Cryptococcus neoformans - ultrastructure; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gastrointestinal Tract - microbiology; Humans; Macrophages - cytology; Macrophages - metabolism; Mice; Mice, Inbred C57BL; Microbiology; Miscellaneous; Mycology; Nematoda; Phagocytosis; Phosphoproteins - genetics; Phosphoproteins - metabolism; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Pulmonary Alveoli - microbiology; Pulmonary Alveoli - pathology; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Survival Rate
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/j.1365-2958.2004.04310.x

Summary Cryptococcal infections are a global cause of significant morbidity and mortality. Recent studies support the hypothesis that virulence of Cryptococcus neoformans may have evolved via survival selection in environmental hosts, such as amoebae and free‐living nematodes. We used killing of the nematode Caenorhabditis elegans by C. neoformans as an assay to screen a library of random C. neoformans insertion mutants. Of 350 mutants tested, seven were identified with attenuated virulence that persisted after crossing the mutation back into a wild‐type strain. Genetic analysis of one strain revealed an insertion in a gene homologous to Saccharomyces cerevisiae KIN1, which encodes a serine/threonine protein kinase. C. neoformans kin1 mutants exhibited significant defects in virulence in murine inhalation and haematogenous infection models and displayed increased binding to alveolar and peritoneal macrophages. The kin1 mutant phenotypes were complemented by the wild‐type KIN1 gene. These findings show that the C. neoformans Kin1 kinase homologue is required for full virulence in disparate hosts and that C. elegans can be used as a substitute host to identify novel factors involved in fungal pathogenesis in mammals.