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

May, Robin Charles

2018-12-02T12:52:29Z

2018-12-02T12:52:29Z

2018-06-04

2018-12-02T12:52:25Z

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.

PPATHOGENS-D-18-00109

1553-7366

1553-7374

https://hdl.handle.net/10161/17690

eng

Public Library of Science (PLoS)

PLoS pathogens

10.1371/journal.ppat.1007126

Science & Technology

Life Sciences & Biomedicine

Microbiology

Parasitology

Virology

PATHOGEN CRYPTOCOCCUS-NEOFORMANS

BETA-GLUCAN RECEPTOR

TOLL-LIKE RECEPTOR-2

WHEAT-GERM LECTIN

SACCHAROMYCES-CEREVISIAE

ANTIFUNGAL IMMUNITY

CYTOKINE PRODUCTION

CANDIDA-ALBICANS

CALCOFLUOR WHITE

CHITIN SYNTHASE

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

Journal article

Alspaugh, J Andrew|0000-0003-3009-627X

e1007126

6

School of Medicine

Duke

Molecular Genetics and Microbiology

Basic Science Departments

Medicine, Infectious Diseases

Medicine

Clinical Science Departments

Published

14