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Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition

The human fungal pathogen, Cryptococcus neoformans, dramatically alters its cell wall, both in size and composition, upon entering the host. This cell wall remodeling is essential for host immune avoidance by this pathogen. In a genetic screen for mutants with changes in their cell wall, we identifi...

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Autores principales: Esher, Shannon K., Ost, Kyla S., Kohlbrenner, Maria A., Pianalto, Kaila M., Telzrow, Calla L., Campuzano, Althea, Nichols, Connie B., Munro, Carol, Wormley, Floyd L., Alspaugh, J. Andrew
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002136/
https://www.ncbi.nlm.nih.gov/pubmed/29864141
http://dx.doi.org/10.1371/journal.ppat.1007126
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author Esher, Shannon K.
Ost, Kyla S.
Kohlbrenner, Maria A.
Pianalto, Kaila M.
Telzrow, Calla L.
Campuzano, Althea
Nichols, Connie B.
Munro, Carol
Wormley, Floyd L.
Alspaugh, J. Andrew
author_facet Esher, Shannon K.
Ost, Kyla S.
Kohlbrenner, Maria A.
Pianalto, Kaila M.
Telzrow, Calla L.
Campuzano, Althea
Nichols, Connie B.
Munro, Carol
Wormley, Floyd L.
Alspaugh, J. Andrew
author_sort Esher, Shannon K.
collection PubMed
description The human fungal pathogen, Cryptococcus neoformans, dramatically alters its cell wall, both in size and composition, upon entering the host. This cell wall remodeling is essential for host immune avoidance by this pathogen. In a genetic screen for mutants with changes in their cell wall, we identified a novel protein, Mar1, that controls cell wall organization and immune evasion. Through phenotypic studies of a loss-of-function strain, we have demonstrated that the mar1Δ mutant has an aberrant cell surface and a defect in polysaccharide capsule attachment, resulting in attenuated virulence. Furthermore, the mar1Δ mutant displays increased staining for exposed cell wall chitin and chitosan when the cells are grown in host-like tissue culture conditions. However, HPLC analysis of whole cell walls and RT-PCR analysis of cell wall synthase genes demonstrated that this increased chitin exposure is likely due to decreased levels of glucans and mannans in the outer cell wall layers. We observed that the Mar1 protein differentially localizes to cellular membranes in a condition dependent manner, and we have further shown that the mar1Δ mutant displays defects in intracellular trafficking, resulting in a mislocalization of the β-glucan synthase catalytic subunit, Fks1. These cell surface changes influence the host-pathogen interaction, resulting in increased macrophage activation to microbial challenge in vitro. We established that several host innate immune signaling proteins are required for the observed macrophage activation, including the Card9 and MyD88 adaptor proteins, as well as the Dectin-1 and TLR2 pattern recognition receptors. These studies explore novel mechanisms by which a microbial pathogen regulates its cell surface in response to the host, as well as how dysregulation of this adaptive response leads to defective immune avoidance.
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spelling pubmed-60021362018-06-25 Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition Esher, Shannon K. Ost, Kyla S. Kohlbrenner, Maria A. Pianalto, Kaila M. Telzrow, Calla L. Campuzano, Althea Nichols, Connie B. Munro, Carol Wormley, Floyd L. Alspaugh, J. Andrew PLoS Pathog Research Article The human fungal pathogen, Cryptococcus neoformans, dramatically alters its cell wall, both in size and composition, upon entering the host. This cell wall remodeling is essential for host immune avoidance by this pathogen. In a genetic screen for mutants with changes in their cell wall, we identified a novel protein, Mar1, that controls cell wall organization and immune evasion. Through phenotypic studies of a loss-of-function strain, we have demonstrated that the mar1Δ mutant has an aberrant cell surface and a defect in polysaccharide capsule attachment, resulting in attenuated virulence. Furthermore, the mar1Δ mutant displays increased staining for exposed cell wall chitin and chitosan when the cells are grown in host-like tissue culture conditions. However, HPLC analysis of whole cell walls and RT-PCR analysis of cell wall synthase genes demonstrated that this increased chitin exposure is likely due to decreased levels of glucans and mannans in the outer cell wall layers. We observed that the Mar1 protein differentially localizes to cellular membranes in a condition dependent manner, and we have further shown that the mar1Δ mutant displays defects in intracellular trafficking, resulting in a mislocalization of the β-glucan synthase catalytic subunit, Fks1. These cell surface changes influence the host-pathogen interaction, resulting in increased macrophage activation to microbial challenge in vitro. We established that several host innate immune signaling proteins are required for the observed macrophage activation, including the Card9 and MyD88 adaptor proteins, as well as the Dectin-1 and TLR2 pattern recognition receptors. These studies explore novel mechanisms by which a microbial pathogen regulates its cell surface in response to the host, as well as how dysregulation of this adaptive response leads to defective immune avoidance. Public Library of Science 2018-06-04 /pmc/articles/PMC6002136/ /pubmed/29864141 http://dx.doi.org/10.1371/journal.ppat.1007126 Text en © 2018 Esher et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Esher, Shannon K.
Ost, Kyla S.
Kohlbrenner, Maria A.
Pianalto, Kaila M.
Telzrow, Calla L.
Campuzano, Althea
Nichols, Connie B.
Munro, Carol
Wormley, Floyd L.
Alspaugh, J. Andrew
Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title_full Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title_fullStr Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title_full_unstemmed Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title_short Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
title_sort defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6002136/
https://www.ncbi.nlm.nih.gov/pubmed/29864141
http://dx.doi.org/10.1371/journal.ppat.1007126
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