title: Modulation of Macrophage Inflammatory Nuclear Factor κB (NF-κB) Signaling by Intracellular Cryptococcus neoformans.
abstract: Cryptococcus neoformans (Cn) is a common facultative intracellular pathogen that can cause life-threatening fungal meningitis in immunocompromised individuals. Shortly after infection, Cn is detectable as both extra- and intracellular yeast particles, with Cn being capable of establishing long-lasting latent infections within host macrophages. Although recent studies have shown that shed capsular polysaccharides and intact extracellular Cn can compromise macrophage function through modulation of NF-κB signaling, it is currently unclear whether intracellular Cn also affects NF-κB signaling. Utilizing live cell imaging and computational modeling, we find that extra- and intracellular Cn support distinct modes of NF-κB signaling in cultured murine macrophages. Specifically, in RAW 264.7 murine macrophages treated with extracellular glucuronoxylomannan (GXM), the major Cn capsular polysaccharide, LPS-induced nuclear translocation of p65 is inhibited, whereas in cells with intracellular Cn, LPS-induced nuclear translocation of p65 is both amplified and sustained. Mathematical simulations and quantification of nascent protein expression indicate that this is a possible consequence of Cn-induced "translational interference," impeding IκBα resynthesis. We also show that long term Cn infection induces stable nuclear localization of p65 and IκBα proteins in the absence of additional pro-inflammatory stimuli. In this case, nuclear localization of p65 is not accompanied by TNFα or inducible NOS (iNOS) expression. These results demonstrate that capsular polysaccharides and intact intracellular yeast manipulate NF-κB via multiple distinct mechanisms and provide new insights into how Cn might modulate cellular signaling at different stages of an infection.
authors.affiliation: From the Departments of Biology and.
authors.forename: James B
authors.initials: JB
authors.lastname: Hayes
authors.affiliation: From the Departments of Biology and.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Sircy
authors.affiliation: From the Departments of Biology and.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Heusinkveld
authors.affiliation: Mathematical Sciences, Middle Tennessee State University, Murfreesboro, Tennessee 37130.
authors.forename: Wandi
authors.initials: W
authors.lastname: Ding
authors.affiliation: Mathematical Sciences, Middle Tennessee State University, Murfreesboro, Tennessee 37130.
authors.forename: Rachel N
authors.initials: RN
authors.lastname: Leander
authors.affiliation: From the Departments of Biology and erin.mcclelland@mtsu.edu.
authors.forename: Erin E
authors.initials: EE
authors.lastname: McClelland
authors.affiliation: From the Departments of Biology and david.e.nelson@mtsu.edu.
authors.forename: David E
authors.initials: DE
authors.lastname: Nelson
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D003453:Cryptococcosis / Q000378:metabolism* / Q000473:pathology; D003455:Cryptococcus neoformans / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D051379:Mice; D008954:Models, Biological; D000072000:NF-KappaB Inhibitor alpha / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D000067996:RAW 264.7 Cells; D051996:Transcription Factor RelA / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D008070:Lipopolysaccharides; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse
keywords: Cryptococcus neoformans; NF-kappa B (NF-KB); computational biology; host-pathogen interaction; inflammation; intracellular pathogen; macrophage