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Networks of fibers and factors: regulation of capsule formation in Cryptococcus neoformans.

Ding H, Mayer FL, Sánchez-León E, de S Araújo GR, Frases S, Kronstad JW - F1000Res (2016)

Bottom Line: The ability of the pathogenic fungus Cryptococcus neoformans to cause life-threatening meningoencephalitis in immunocompromised individuals is due in large part to elaboration of a capsule consisting of polysaccharide fibers.Recent studies reveal a complex network of transcription factors that influence capsule elaboration in response to several different signals of relevance to disease (e.g., iron deprivation).The emerging complexity of the network is consistent with the diversity of conditions that influence the capsule and illustrates the responsiveness of the fungus to both the environment and mammalian hosts.

View Article: PubMed Central - PubMed

Affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, Canada.

ABSTRACT
The ability of the pathogenic fungus Cryptococcus neoformans to cause life-threatening meningoencephalitis in immunocompromised individuals is due in large part to elaboration of a capsule consisting of polysaccharide fibers. The size of the cell-associated capsule is remarkably responsive to a variety of environmental and host conditions, but the mechanistic details of the regulation, synthesis, trafficking, and attachment of the polysaccharides are poorly understood. Recent studies reveal a complex network of transcription factors that influence capsule elaboration in response to several different signals of relevance to disease (e.g., iron deprivation). The emerging complexity of the network is consistent with the diversity of conditions that influence the capsule and illustrates the responsiveness of the fungus to both the environment and mammalian hosts.

No MeSH data available.


Related in: MedlinePlus

The network of polysaccharide fibers surroundingCryptococcus neoformans cells.(a) Conventional scanning electron microscopy showing the network of capsular fibers around two yeast cells marked by arrowheads. Bar, 5 μm. (b) High-resolution scanning electron microscopy of the network of capsule fibers. Bar, 100 nm. The methods to generate the images are described in the study of Araújoet al.8.
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f1: The network of polysaccharide fibers surroundingCryptococcus neoformans cells.(a) Conventional scanning electron microscopy showing the network of capsular fibers around two yeast cells marked by arrowheads. Bar, 5 μm. (b) High-resolution scanning electron microscopy of the network of capsule fibers. Bar, 100 nm. The methods to generate the images are described in the study of Araújoet al.8.

Mentions: The ability ofC. neoformans to cause disease is due in large part to its production of a capsule made up of fibers of two polysaccharides, glucuronoxylomannan (GXM) and glucuronoxylomannogalactan (GXMGal) (Figure 1)8–12. The capsule is thought to protect cells from desiccation in the environment, and the GXM and GXMGal polysaccharides have immunomodulatory properties during disease in vertebrate hosts12,13. Acapsular mutants are generally avirulent, while many hypercapsular mutants show enhanced virulence in a mouse model of cryptococcosis12–15. Additional virulence traits include the formation of melanin in the cell wall, survival in macrophages and at host temperature, acquisition of limited nutrients in the host (e.g., iron), and production of extracellular enzymes such as urease and phospholipase B9,16.


Networks of fibers and factors: regulation of capsule formation in Cryptococcus neoformans.

Ding H, Mayer FL, Sánchez-León E, de S Araújo GR, Frases S, Kronstad JW - F1000Res (2016)

The network of polysaccharide fibers surroundingCryptococcus neoformans cells.(a) Conventional scanning electron microscopy showing the network of capsular fibers around two yeast cells marked by arrowheads. Bar, 5 μm. (b) High-resolution scanning electron microscopy of the network of capsule fibers. Bar, 100 nm. The methods to generate the images are described in the study of Araújoet al.8.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4979528&req=5

f1: The network of polysaccharide fibers surroundingCryptococcus neoformans cells.(a) Conventional scanning electron microscopy showing the network of capsular fibers around two yeast cells marked by arrowheads. Bar, 5 μm. (b) High-resolution scanning electron microscopy of the network of capsule fibers. Bar, 100 nm. The methods to generate the images are described in the study of Araújoet al.8.
Mentions: The ability ofC. neoformans to cause disease is due in large part to its production of a capsule made up of fibers of two polysaccharides, glucuronoxylomannan (GXM) and glucuronoxylomannogalactan (GXMGal) (Figure 1)8–12. The capsule is thought to protect cells from desiccation in the environment, and the GXM and GXMGal polysaccharides have immunomodulatory properties during disease in vertebrate hosts12,13. Acapsular mutants are generally avirulent, while many hypercapsular mutants show enhanced virulence in a mouse model of cryptococcosis12–15. Additional virulence traits include the formation of melanin in the cell wall, survival in macrophages and at host temperature, acquisition of limited nutrients in the host (e.g., iron), and production of extracellular enzymes such as urease and phospholipase B9,16.

Bottom Line: The ability of the pathogenic fungus Cryptococcus neoformans to cause life-threatening meningoencephalitis in immunocompromised individuals is due in large part to elaboration of a capsule consisting of polysaccharide fibers.Recent studies reveal a complex network of transcription factors that influence capsule elaboration in response to several different signals of relevance to disease (e.g., iron deprivation).The emerging complexity of the network is consistent with the diversity of conditions that influence the capsule and illustrates the responsiveness of the fungus to both the environment and mammalian hosts.

View Article: PubMed Central - PubMed

Affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, Canada.

ABSTRACT
The ability of the pathogenic fungus Cryptococcus neoformans to cause life-threatening meningoencephalitis in immunocompromised individuals is due in large part to elaboration of a capsule consisting of polysaccharide fibers. The size of the cell-associated capsule is remarkably responsive to a variety of environmental and host conditions, but the mechanistic details of the regulation, synthesis, trafficking, and attachment of the polysaccharides are poorly understood. Recent studies reveal a complex network of transcription factors that influence capsule elaboration in response to several different signals of relevance to disease (e.g., iron deprivation). The emerging complexity of the network is consistent with the diversity of conditions that influence the capsule and illustrates the responsiveness of the fungus to both the environment and mammalian hosts.

No MeSH data available.


Related in: MedlinePlus