Core -Glycan Structures Are Critical for the Pathogenicity of Cryptococcus neoformans by Modulating Host Cell Death.

is a human-pathogenic fungal pathogen that causes life-threatening meningoencephalitis in immunocompromised individuals. To investigate the roles of -glycan core structure in cryptococcal pathogenicity, we constructed mutant strains of with defects in the assembly of lipid-linked -glycans in the luminal side of the endoplasmic reticulum (ER). Deletion of (Δ), which encodes dolichyl-phosphate-mannose (Dol-P-Man)-dependent α-1,3-mannosyltransferase, resulted in the production of truncated neutral -glycans carrying five mannose residues as a major species. Despite moderate or nondetectable defects in virulence-associated phenotypes , the Δ 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 and , encoding Dol-P-Man-dependent α-1,2-mannosyltransferases and α-1,6-mannosyltransferases, generating truncated core -glycans with six and seven mannose residues, respectively, also displayed remarkably reduced macrophage cell death and virulence. However, secretion levels of interleukin-1β (IL-1β) were not reduced in the bone marrow-derived dendritic cells obtained from - and -deficient mice infected with the Δ mutant strain, excluding the possibility that pyroptosis is a main host cell death pathway dependent on intact core -glycans. Our results demonstrated -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 We previously reported that the outer mannose chains of -glycans are dispensable for the virulence of , which is in stark contrast to findings for the other human-pathogenic yeast, Here, we present evidence that an intact core -glycan structure is required for pathogenicity by systematically analyzing , and strains that have defects in lipid-linked glycan assembly and in virulence. The null mutants producing truncated core -glycans were defective in inducing host cell death after phagocytosis, which is triggered as a mechanism of pulmonary escape and dissemination of , thus becoming inactive in causing fatal infection. The results clearly demonstrated the critical features of the -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.