Membrane microdomain components of Histoplasma capsulatum yeast forms, and their role in alveolar macrophage infectivity
Analysis of membrane lipids of Histoplasma capsulatum showed that similar to 40% of fungal ergosterol is present in membrane microdomain fractions resistant to treatment with non-ionic detergent at 4 degrees C. Specific proteins were also enriched in these fractions, particularly Pma1p a yeast micro...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2012 |
| País: | Brasil |
| Institución: | Universidade Federal de São Paulo (UNIFESP) |
| Repositorio: | Repositório Institucional da UNIFESP |
| Idioma: | inglés |
| OAI Identifier: | oai:repositorio.unifesp.br:11600/34631 |
| Acceso en línea: | http://dx.doi.org/10.1016/j.bbamem.2011.12.008 http://repositorio.unifesp.br/handle/11600/34631 |
| Access Level: | acceso abierto |
| Palabra clave: | Histoplasma capsulatum Membrane microdomain Ergosterol Macrophage infectivity Glycosphingolipids Methyl-beta-cyclodextrin |
| Sumario: | Analysis of membrane lipids of Histoplasma capsulatum showed that similar to 40% of fungal ergosterol is present in membrane microdomain fractions resistant to treatment with non-ionic detergent at 4 degrees C. Specific proteins were also enriched in these fractions, particularly Pma1p a yeast microdomain protein marker (a plasma membrane proton ATPase), a 30 kDa laminin-binding protein, and a 50 kDa protein recognized by anti-alpha 5-integrin antibody. To better understand the role of ergosterol-dependent microdomains in fungal biology and pathogenicity, H. capsulatum yeast forms were treated with a sterol chelator, methyl-beta-cyclodextrin (m beta CD). Removal of ergosterol by m beta CD incubation led to disorganization of ergosterol-enriched microdomains containing Pma1p and the 30 kDa protein, resulting in displacement of these proteins from detergent-insoluble to -soluble fractions in sucrose density gradient ultracentrifugation. m beta CD treatment did not displace/remove the 50 kDa alpha 5-integrin-like protein nor had effect on the organization of glycosphingolipids present in the detergent-resistant fractions. Ergosterol-enriched membrane microdomains were also shown to be important for infectivity of alveolar macrophages; after treatment of yeasts with m beta CD, macrophage infectivity was reduced by 45%. These findings suggest the existence of two populations of detergent-resistant membrane microdomains in H. capsulatum yeast forms: (i) ergosterol-independent microdomains rich in integrin-like proteins and glycosphingolipids, possibly involved in signal transduction; (ii) ergosterol-enriched microdomains containing Pma1p and the 30 kDa laminin-binding protein; ergosterol and/or the 30 kDa protein may be involved in macrophage infectivity. (C) 2011 Elsevier B.V. All rights reserved. |
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