Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death

ABSTRACT Cryptococcus neoformans is a human-pathogenic fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised individuals. To investigate the roles of N-glycan core structure in cryptococcal pathogenicity, we constructed mutant strains of C. neoformans with defects in...

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Autores principales:	Eun Jung Thak, Su-Bin Lee, Shengjie Xu-Vanpala, Dong-Jik Lee, Seung-Yeon Chung, Yong-Sun Bahn, Doo-Byoung Oh, Mari L. Shinohara, Hyun Ah Kang
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	Cryptococcus neoformans N-linked protein glycosylation ALG fungal pathogenesis Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/b1306970de3b4feeaf9f379aec9d5bc6
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spelling	oai:doaj.org-article:b1306970de3b4feeaf9f379aec9d5bc62021-11-15T15:56:46ZCore <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death10.1128/mBio.00711-202150-7511https://doaj.org/article/b1306970de3b4feeaf9f379aec9d5bc62020-06-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00711-20https://doaj.org/toc/2150-7511ABSTRACT Cryptococcus neoformans is a human-pathogenic fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised individuals. To investigate the roles of N-glycan core structure in cryptococcal pathogenicity, we constructed mutant strains of C. neoformans with defects in the assembly of lipid-linked N-glycans in the luminal side of the endoplasmic reticulum (ER). Deletion of ALG3 (alg3Δ), which encodes dolichyl-phosphate-mannose (Dol-P-Man)-dependent α-1,3-mannosyltransferase, resulted in the production of truncated neutral N-glycans carrying five mannose residues as a major species. Despite moderate or nondetectable defects in virulence-associated phenotypes in vitro, the alg3Δ mutant was avirulent in a mouse model of systemic cryptococcosis. Notably, the mutant did not show defects in early stages of host cell interaction during infection, including attachment to lung epithelial cells, opsonic/nonopsonic phagocytosis, and manipulation of phagosome acidification. However, the ability to drive macrophage cell death was greatly decreased in this mutant, without loss of cell wall remodeling capacity. Furthermore, deletion of ALG9 and ALG12, encoding Dol-P-Man-dependent α-1,2-mannosyltransferases and α-1,6-mannosyltransferases, generating truncated core N-glycans with six and seven mannose residues, respectively, also displayed remarkably reduced macrophage cell death and in vivo virulence. However, secretion levels of interleukin-1β (IL-1β) were not reduced in the bone marrow-derived dendritic cells obtained from Asc- and Gsdmd-deficient mice infected with the alg3Δ mutant strain, excluding the possibility that pyroptosis is a main host cell death pathway dependent on intact core N-glycans. Our results demonstrated N-glycan structures as a critical feature in modulating death of host cells, which is exploited by as a strategy for host cell escape for dissemination of C. neoformans. IMPORTANCE We previously reported that the outer mannose chains of N-glycans are dispensable for the virulence of C. neoformans, which is in stark contrast to findings for the other human-pathogenic yeast, Candida albicans. Here, we present evidence that an intact core N-glycan structure is required for C. neoformans pathogenicity by systematically analyzing alg3Δ, alg9Δ, and alg12Δ strains that have defects in lipid-linked N-glycan assembly and in in vivo virulence. The alg null mutants producing truncated core N-glycans were defective in inducing host cell death after phagocytosis, which is triggered as a mechanism of pulmonary escape and dissemination of C. neoformans, thus becoming inactive in causing fatal infection. The results clearly demonstrated the critical features of the N-glycan structure in mediating the interaction with host cells during fungal infection. The delineation of the roles of protein glycosylation in fungal pathogenesis not only provides insight into the glycan-based fungal infection mechanism but also will aid in the development of novel antifungal agents.Eun Jung ThakSu-Bin LeeShengjie Xu-VanpalaDong-Jik LeeSeung-Yeon ChungYong-Sun BahnDoo-Byoung OhMari L. ShinoharaHyun Ah KangAmerican Society for MicrobiologyarticleCryptococcus neoformansN-linked protein glycosylationALGfungal pathogenesisMicrobiologyQR1-502ENmBio, Vol 11, Iss 3 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Cryptococcus neoformans N-linked protein glycosylation ALG fungal pathogenesis Microbiology QR1-502
spellingShingle	Cryptococcus neoformans N-linked protein glycosylation ALG fungal pathogenesis Microbiology QR1-502 Eun Jung Thak Su-Bin Lee Shengjie Xu-Vanpala Dong-Jik Lee Seung-Yeon Chung Yong-Sun Bahn Doo-Byoung Oh Mari L. Shinohara Hyun Ah Kang Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
description	ABSTRACT Cryptococcus neoformans is a human-pathogenic fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised individuals. To investigate the roles of N-glycan core structure in cryptococcal pathogenicity, we constructed mutant strains of C. neoformans with defects in the assembly of lipid-linked N-glycans in the luminal side of the endoplasmic reticulum (ER). Deletion of ALG3 (alg3Δ), which encodes dolichyl-phosphate-mannose (Dol-P-Man)-dependent α-1,3-mannosyltransferase, resulted in the production of truncated neutral N-glycans carrying five mannose residues as a major species. Despite moderate or nondetectable defects in virulence-associated phenotypes in vitro, the alg3Δ mutant was avirulent in a mouse model of systemic cryptococcosis. Notably, the mutant did not show defects in early stages of host cell interaction during infection, including attachment to lung epithelial cells, opsonic/nonopsonic phagocytosis, and manipulation of phagosome acidification. However, the ability to drive macrophage cell death was greatly decreased in this mutant, without loss of cell wall remodeling capacity. Furthermore, deletion of ALG9 and ALG12, encoding Dol-P-Man-dependent α-1,2-mannosyltransferases and α-1,6-mannosyltransferases, generating truncated core N-glycans with six and seven mannose residues, respectively, also displayed remarkably reduced macrophage cell death and in vivo virulence. However, secretion levels of interleukin-1β (IL-1β) were not reduced in the bone marrow-derived dendritic cells obtained from Asc- and Gsdmd-deficient mice infected with the alg3Δ mutant strain, excluding the possibility that pyroptosis is a main host cell death pathway dependent on intact core N-glycans. Our results demonstrated N-glycan structures as a critical feature in modulating death of host cells, which is exploited by as a strategy for host cell escape for dissemination of C. neoformans. IMPORTANCE We previously reported that the outer mannose chains of N-glycans are dispensable for the virulence of C. neoformans, which is in stark contrast to findings for the other human-pathogenic yeast, Candida albicans. Here, we present evidence that an intact core N-glycan structure is required for C. neoformans pathogenicity by systematically analyzing alg3Δ, alg9Δ, and alg12Δ strains that have defects in lipid-linked N-glycan assembly and in in vivo virulence. The alg null mutants producing truncated core N-glycans were defective in inducing host cell death after phagocytosis, which is triggered as a mechanism of pulmonary escape and dissemination of C. neoformans, thus becoming inactive in causing fatal infection. The results clearly demonstrated the critical features of the N-glycan structure in mediating the interaction with host cells during fungal infection. The delineation of the roles of protein glycosylation in fungal pathogenesis not only provides insight into the glycan-based fungal infection mechanism but also will aid in the development of novel antifungal agents.
format	article
author	Eun Jung Thak Su-Bin Lee Shengjie Xu-Vanpala Dong-Jik Lee Seung-Yeon Chung Yong-Sun Bahn Doo-Byoung Oh Mari L. Shinohara Hyun Ah Kang
author_facet	Eun Jung Thak Su-Bin Lee Shengjie Xu-Vanpala Dong-Jik Lee Seung-Yeon Chung Yong-Sun Bahn Doo-Byoung Oh Mari L. Shinohara Hyun Ah Kang
author_sort	Eun Jung Thak
title	Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
title_short	Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
title_full	Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
title_fullStr	Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
title_full_unstemmed	Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death
title_sort	core <italic toggle="yes">n</italic>-glycan structures are critical for the pathogenicity of <named-content content-type="genus-species">cryptococcus neoformans</named-content> by modulating host cell death
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/b1306970de3b4feeaf9f379aec9d5bc6
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Core <italic toggle="yes">N</italic>-Glycan Structures Are Critical for the Pathogenicity of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> by Modulating Host Cell Death

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