scholarly journals Role of clathrin-mediated endocytosis in the use of heme and hemoglobin by the fungal pathogen Cryptococcus neoformans

2018 ◽  
Vol 21 (3) ◽  
pp. e12961 ◽  
Author(s):  
Gaurav Bairwa ◽  
Mélissa Caza ◽  
Linda Horianopoulos ◽  
Guanggan Hu ◽  
James Kronstad
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen

scholarly journals Cryptococcus neoformans Evades Pulmonary Immunity by Modulating Xylose Precursor Transport

2020 ◽  
Vol 88 (8) ◽  
Author(s):  
Lucy X. Li ◽  
Camaron R. Hole ◽  
Javier Rangel-Moreno ◽  
Shabaana A. Khader ◽  
Tamara L. Doering
Keyword(s):  
Cryptococcus Neoformans ◽  
Mutant Strain ◽  
Fungal Pathogen ◽  
Wild Type ◽  
Content Type ◽  
Helper Cell Type ◽  
Lymphoid Structures ◽  
Type Infection

ABSTRACT Cryptococcus neoformans is a fungal pathogen that kills almost 200,000 people each year and is distinguished by abundant and unique surface glycan structures that are rich in xylose. A mutant strain of C. neoformans that cannot transport xylose precursors into the secretory compartment is severely attenuated in virulence in mice yet surprisingly is not cleared. We found that this strain failed to induce the nonprotective T helper cell type 2 (Th2) responses characteristic of wild-type infection, instead promoting sustained interleukin 12p40 (IL-12p40) induction and increased IL-17A (IL-17) production. It also stimulated dendritic cells to release high levels of proinflammatory cytokines, a behavior we linked to xylose expression. We further discovered that inducible bronchus-associated lymphoid tissue (iBALT) forms in response to infection with either wild-type cryptococci or the mutant strain with reduced surface xylose; although iBALT formation is slowed in the latter case, the tissue is better organized. Finally, our temporal studies suggest that lymphoid structures in the lung restrict the spread of mutant fungi for at least 18 weeks after infection, which is in contrast to ineffective control of the pathogen after infection with wild-type cells. These studies demonstrate the role of xylose in modulation of host response to a fungal pathogen and show that cryptococcal infection triggers iBALT formation.

scholarly journals A Predicted Mannoprotein Cmp1 Regulates Fungal Virulence in Cryptococcus neoformans

Pathogens ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 881
Author(s):  
Lian-Tao Han ◽  
Lei Wu ◽  
Tong-Bao Liu
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Gene Expression Pattern ◽  
Fungal Virulence ◽  
Human Fungal Pathogen ◽  
Overexpression Strain ◽  
Reproduction Process ◽  
Localization Analysis ◽  
Survival Assay

The capsule of the fungal pathogen Cryptococcus neoformans consists of glucuronoxylomannan (GXM), glucuronoxylomannogalactan (GXMGal), and mannoproteins (MPs). MPs are a kind of glycoproteins with low content but high immunogenicity, which can stimulate the immune protection of the host. However, there is not much information about the role of mannoproteins in virulence of the human fungal pathogen C. neoformans. In this study, we reported the identification and functional analysis of a predicted mannoprotein Cmp1 that regulates fungal virulence in C. neoformans. Gene expression pattern analysis indicates that the CMP1 gene was ubiquitously expressed at all stages of cryptococcal development. Subcellular localization analysis indicated that Cmp1 was localized in the cytoplasm of cryptococcal cells. Disruption or overexpression of CMP1 results in impairing capsule formation in Cryptococcus, but it does not affect the melanin production and sensitivity under various stress conditions, nor does it affect the sexual reproduction process of Cryptococcus. Survival assay showed that the pathogenicity of the cmp1Δ mutant or the CMP1 overexpression strain was significantly attenuated in a murine inhalation model of cryptococcosis. In conclusion, our findings implied that the mannoprotein Cmp1 is required for the virulence of C. neoformans.

scholarly journals Zinc Finger Proteins in the Human Fungal Pathogen Cryptococcus neoformans

2020 ◽  
Vol 21 (4) ◽  
pp. 1361
Author(s):  
Yuan-Hong Li ◽  
Tong-Bao Liu
Keyword(s):  
Cryptococcus Neoformans ◽  
Zinc Finger ◽  
Fungal Pathogen ◽  
Ion Homeostasis ◽  
Zinc Finger Proteins ◽  
Morphological Development ◽  
Human Fungal Pathogen ◽  
Essential Trace Elements

Zinc is one of the essential trace elements in eukaryotes and it is a critical structural component of a large number of proteins. Zinc finger proteins (ZNFs) are zinc-finger domain-containing proteins stabilized by bound zinc ions and they form the most abundant proteins, serving extraordinarily diverse biological functions. In recent years, many ZNFs have been identified and characterized in the human fungal pathogen Cryptococcus neoformans, a fungal pathogen causing fatal meningitis mainly in immunocompromised individuals. It has been shown that ZNFs play important roles in the morphological development, differentiation, and virulence of C. neoformans. In this review, we, first, briefly introduce the ZNFs and their classification. Then, we explain the identification and classification of the ZNFs in C. neoformans. Next, we focus on the biological role of the ZNFs functionally characterized so far in the sexual reproduction, virulence factor production, ion homeostasis, pathogenesis, and stress resistance in C. neoformans. We also discuss the perspectives on future function studies of ZNFs in C. neoformans.

scholarly journals Role of clathrin-mediated endocytosis in the use of heme and hemoglobin by the fungal pathogen Cryptococcus neoformans

2018 ◽  
Author(s):  
Gaurav Bairwa ◽  
Mélissa Caza ◽  
Linda Horianopoulos ◽  
Guanggan Hu ◽  
James Kronstad
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Sugar Metabolism ◽  
Heme Iron ◽  
Heme Uptake ◽  
Iron Source ◽  
Life Threatening ◽  
Uptake Process ◽  
Underlying Mechanisms

SummaryHeme is a major source of iron for pathogens of humans, and its use is critical in determining the outcome of infection and disease. Cryptococcus neoformans is an encapsulated fungal pathogen that causes life-threatening infections in immunocompromised individuals. C. neoformans effectively uses heme as an iron source but the underlying mechanisms are poorly defined. Non-iron metalloporphyrins (MPPs) are toxic analogues of heme and are thought to enter microbial cells via endogenous heme acquisition systems. We therefore carried out a mutant screen for susceptibility against manganese metalloporphyrin (Mn MPP) to identify new components for heme uptake in C. neoformans. We identified several genes involved in signaling, DNA repair, sugar metabolism and trafficking that play important roles in susceptibility to Mn MPP and in the use of heme as an iron source. We focused on investigating the role of clathrin-mediated endocytosis (CME) and found that several components of CME including Chc1, Las17, Rvs161 and Rvs167 are required for growth on heme and hemoglobin, and for endocytosis and intracellular trafficking of these molecules. We show that the hemoglobin uptake process in C. neoformans involves clathrin heavy chain, Chc1, which appears to co-localize with hemoglobin containing-vesicles and to potentially assist in proper delivery of hemoglobin to the vacuole. Additionally, C. neoformans strains lacking Chc1, Las17, Rvs161, or Rvs167 were defective in the elaboration of several key virulence factors and a las17 mutant was avirulent in a mouse model of cryptococcosis. Overall, this study unveils crucial functions of CME in the use of heme iron by C. neoformans and reveals a role for CME in fungal pathogenesis.

Role of the fungus-specific flavin carrier Flc1 in antifungal resistance in the fungal pathogen Cryptococcus neoformans

2018 ◽  
Vol 57 (4) ◽  
pp. 468-477 ◽  
Author(s):  
Ping Zhang ◽  
Chenxi Li ◽  
Liang Huo ◽  
Biyun Xiang ◽  
Kashif Rahim ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Fungal Pathogen ◽  
Antifungal Resistance

scholarly journals Cryptococcus neoformans evades pulmonary immunity by modulating xylose precursor transport

2019 ◽  
Author(s):  
Lucy X. Li ◽  
Camaron R. Hole ◽  
Javier Rangel-Moreno ◽  
Shabaana A. Khader ◽  
Tamara L. Doering
Keyword(s):  
Cryptococcus Neoformans ◽  
Mutant Strain ◽  
Fungal Pathogen ◽  
Wild Type ◽  
Helper Cell Type ◽  
Lymphoid Structures ◽  
Type Infection ◽  
Reduced Surface

ABSTRACTCryptococcus neoformans is a fungal pathogen that kills almost 200,000 people each year and is distinguished by abundant and unique surface glycan structures that are rich in xylose. A mutant strain of C. neoformans that cannot transport xylose precursors into the secretory compartment is severely attenuated in virulence in mice, yet surprisingly is not cleared. We found that this strain failed to induce the non-protective T helper cell type 2 (Th2) responses characteristic of wild-type infection, instead promoting sustained Interleukin (IL)-12p40 induction and increased IL-17A (IL-17) production. It also stimulated dendritic cells to release high levels of pro-inflammatory cytokines, a behavior we linked to xylose expression. We further discovered that inducible bronchus associated lymphoid tissue (iBALT) forms in response to infection with either wild-type cryptococci or the mutant strain with reduced surface xylose; although iBALT formation is slowed in the latter case, the tissue is better organized. Finally, our temporal studies suggest that lymphoid structures in the lung restrict the spread of mutant fungi for at least 18 weeks after infection, in contrast to ineffective control of the pathogen after infection with wild-type cells. These studies demonstrate the role of xylose in modulation of host response to a fungal pathogen and show that cryptococcal infection triggers iBALT formation.

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