1
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Gaylord EA, Choy HL, Chen G, Briner SL, Doering TL. Sac1 links phosphoinositide turnover to cryptococcal virulence. mBio 2024:e0149624. [PMID: 38953635 DOI: 10.1128/mbio.01496-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Accepted: 05/24/2024] [Indexed: 07/04/2024] Open
Abstract
Cryptococcus neoformans is an environmentally acquired fungal pathogen that causes over 140,000 deaths per year. Cryptococcal infection occurs when infectious particles are deposited into the lung, where they encounter host phagocytic cells. C. neoformans may be engulfed by these phagocytes, an important step of infection that leads to outcomes ranging from termination of infection to cryptococcal dissemination. To study this critical process, we screened approximately 4,700 cryptococcal gene deletion mutants for altered uptake, using primary mouse and human phagocytic cells. Among the hits of these two screens, we identified 93 mutants with perturbed uptake in both systems, as well as others with differences in uptake by only one cell type. We further screened the hits for changes in thickness of the capsule, a protective polysaccharide layer around the cell which is an important cryptococcal virulence factor. The combination of our three screens yielded 45 mutants, including one lacking the phosphatidylinositol-4-phosphate phosphatase Sac1. In this work, we implicate Sac1 in both host cell uptake and capsule production. We found that sac1 mutants exhibit lipid trafficking defects, reductions in secretory system function, and changes in capsule size and composition. Many of these changes occur specifically in tissue culture media, highlighting the role of Sac1 phosphatase activity in responding to the stress of host-like conditions. Overall, these findings show how genome-scale screening can identify cellular factors that contribute to our understanding of cryptococcal biology and demonstrate the role of Sac1 in determining fungal virulence.IMPORTANCECryptococcus neoformans is a fungal pathogen with significant impact on global health. Cryptococcal cells inhaled from the environment are deposited into the lungs, where they first contact the human immune system. The interaction between C. neoformans and host cells is critical because this step of infection can determine whether the fungal cells die or proliferate within the human host. Despite the importance of this stage of infection, we have limited knowledge of cryptococcal factors that influence its outcome. In this study, we identify cryptococcal genes that affect uptake by both human and mouse cells. We also identify mutants with altered capsule, a protective coating that surrounds the cells to shield them from the host immune system. Finally, we characterize the role of one gene, SAC1, in these processes. Overall, this study contributes to our understanding of how C. neoformans interacts with and protects itself from host cells.
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Affiliation(s)
- Elizabeth A Gaylord
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Hau Lam Choy
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Guohua Chen
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Sydney L Briner
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Tamara L Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
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2
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Hughes ES, Tuck LR, He Z, Ballou ER, Wallace EWJ. A trade-off between proliferation and defense in the fungal pathogen Cryptococcus at alkaline pH is controlled by the transcription factor GAT201. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.14.543486. [PMID: 37398450 PMCID: PMC10312749 DOI: 10.1101/2023.06.14.543486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Cryptococcus is a fungal pathogen whose virulence relies on proliferation in and dissemination to host sites, and on synthesis of a defensive yet metabolically costly polysaccharide capsule. Regulatory pathways required for Cryptococcus virulence include a GATA-like transcription factor, Gat201, that regulates Cryptococcal virulence in both capsule-dependent and capsule-independent ways. Here we show that Gat201 is part of a negative regulatory pathway that limits fungal survival at alkaline pH. RNA-seq analysis found strong induction of GAT201 expression within minutes of transfer to RPMI media at alkaline pH. Microscopy, growth curves, and colony forming unit assays show that in RPMI at alkaline pH wild-type Cryptococcus neoformans yeast cells produce capsule but do not bud or maintain viability, while gat201Δ cells make buds and maintain viability, yet fail to produce capsule. GAT201 is required for transcriptional upregulation of a specific set of genes, the majority of which are direct Gat201 targets. Evolutionary analysis shows that Gat201 is in a subfamily of GATA-like transcription factors that is conserved within pathogenic fungi but absent in model yeasts. This work identifies the Gat201 pathway as controlling a trade-off between proliferation and production of defensive capsule. The assays established here will allow characterisation of the mechanisms of action of the Gat201 pathway. Together, our findings urge improved understanding of the regulation of proliferation as a driver of fungal pathogenesis.
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Affiliation(s)
- Elizabeth S Hughes
- Institute for Cell Biology, and Centre for Engineering Biology, School of Biological Sciences, The University of Edinburgh
| | - Laura R Tuck
- Institute for Cell Biology, and Centre for Engineering Biology, School of Biological Sciences, The University of Edinburgh
| | - Zhenzhen He
- Institute for Cell Biology, and Centre for Engineering Biology, School of Biological Sciences, The University of Edinburgh
| | | | - Edward W J Wallace
- Institute for Cell Biology, and Centre for Engineering Biology, School of Biological Sciences, The University of Edinburgh
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3
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Gaylord EA, Choy HL, Chen G, Briner SL, Doering TL. Sac1 links phosphoinositide turnover to cryptococcal virulence. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576303. [PMID: 38293062 PMCID: PMC10827209 DOI: 10.1101/2024.01.18.576303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Cryptococcus neoformans is an environmentally-acquired fungal pathogen that causes over 140,000 deaths per year. Cryptococcal infection occurs when infectious particles are deposited into the lung, where they encounter host phagocytic cells. C. neoformans may be engulfed by these phagocytes, an important step of infection that leads to outcomes ranging from termination of infection to cryptococcal dissemination. To study this critical process, we screened approximately 4,700 cryptococcal gene deletion mutants for altered uptake, using primary mouse and human phagocytic cells. Among the hits of these two screens, we identified 93 mutants with perturbed uptake in both systems, as well as others with differences in uptake by only one cell type. We further screened the hits for changes in thickness of the capsule, a protective polysaccharide layer around the cell which is an important cryptococcal virulence factor. The combination of our three screens yielded 45 mutants, including one lacking the phosphatidylinositol-4-phosphate phosphatase Sac1. In this work, we implicate Sac1 in both host cell uptake and capsule production. We found that sac1 mutants exhibit lipid trafficking defects, reductions in secretory system function, and changes in capsule size and composition. Many of these changes occur specifically in tissue culture media, highlighting the role of Sac1 phosphatase activity in responding to the stress of host-like conditions. Overall, these findings show how genome-scale screening can identify cellular factors that contribute to our understanding of cryptococcal biology and demonstrate the role of Sac1 in determining fungal virulence. IMPORTANCE Cryptococcus neoformans is a fungal pathogen with significant impact on global health. Cryptococcal cells inhaled from the environment are deposited into the lungs, where they first contact the human immune system. The interaction between C. neoformans and host cells is critical because this step of infection can determine whether the fungal cells die or proliferate within the human host. Despite the importance of this stage of infection, we have limited knowledge of cryptococcal factors that influence its outcome. In this study, we identify cryptococcal genes that affect uptake by both human and mouse cells. We also identify mutants with altered capsule, a protective coating that surrounds the cells to shield them from the host immune system. Finally, we characterize the role of one gene, SAC1 , in these processes. Overall, this study contributes to our understanding of how C. neoformans interacts with and protects itself from host cells.
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4
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Wei S, Zhang Y, Wu M, Lv Y, Zhang S, Zhai H, Hu Y. Mechanisms of methyl 2-methylbutyrate suppression on Aspergillus flavus growth and aflatoxin B1 biosynthesis. Int J Food Microbiol 2024; 409:110462. [PMID: 37918192 DOI: 10.1016/j.ijfoodmicro.2023.110462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/17/2023] [Accepted: 10/26/2023] [Indexed: 11/04/2023]
Abstract
Aspergillus flavus and subsequently produced carcinogenic aflatoxins frequently contaminate postharvest food crops, resulting in a threat to global food safety. Chemical preservatives are currently the main antifungal agents. However, fungal resistance effect, biological toxicity, and environmental contamination limit their practical applications. The application of natural volatile organic compounds has great potential for controlling fungal and mycotoxin contamination of postharvest food crops. This study therefore investigated the antifungal and anti-aflatoxigenic activities of the volatile compound, methyl 2-methylbutyrate (M2M), against Aspergillus flavus and its potential mechanisms. M2M effectively inhibited A. flavus mycelia growth, with a minimum inhibitory concentration of 2.0 μL/mL. Moreover, M2M also suppressed aflatoxin production, sclerotia production, and the pathogenicity on peanut and corn flour. RNA-Seq results showed that 2899 differentially expressed genes (DEGs), and DEGs involved in ergosterol synthesis, cell wall structure, glycolysis, citric acid cycle, mitogen activated protein kinase signaling pathway, DNA replication, and aflatoxin biosynthesis, were down-regulated in A. flavus. Further studies showed that M2M strongly damaged the cell membrane and cell wall integrity, reduced ATP levels, and induced reactive oxygen species (ROS) accumulation and DNA damage. Notably, a GATA type zinc finger transcription factor, AfSreA (AFLA_132440), which is essential for A. flavus growth and aflatoxin production, was identified. The growth and aflatoxin yield in the ΔAfSreA strain decreased by 94.94 % and 71.82 %, respectively. Additionally, deletion of AfSreA destroyed cell wall integrity and decreased expressions of genes involved in aflatoxin biosynthesis. Taken together, our results identified the antifungal and anti-aflatoxigenic mechanisms of M2M against A. flavus, and confirmed the potential of M2M in protecting peanut and corn from fungal contamination.
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Affiliation(s)
- Shan Wei
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Yige Zhang
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Menghan Wu
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Yangyong Lv
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Shuaibing Zhang
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Huanchen Zhai
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China
| | - Yuansen Hu
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, PR China; Food Laboratory of Zhongyuan, Henan University of Technology, Luohe 462300, PR China.
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Li C, Meng Y, Li H, Du W, Gao X, Suo C, Gao Y, Ni Y, Sun T, Yang S, Lan T, Xin M, Ding C. Immunization with a heat-killed prm1 deletion strain protects the host from Cryptococcus neoformans infection. Emerg Microbes Infect 2023; 12:2244087. [PMID: 37526401 PMCID: PMC10431737 DOI: 10.1080/22221751.2023.2244087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/02/2023] [Accepted: 07/30/2023] [Indexed: 08/02/2023]
Abstract
Systemic infection with Cryptococcus neoformans, a dangerous and contagious pathogen found throughout the world, frequently results in lethal cryptococcal pneumonia and meningoencephalitis, and no effective treatments and vaccination of cryptococcosis are available. Here, we describe Prm1, a novel regulator of C. neoformans virulence. C. neoformans prm1Δ cells exhibit extreme sensitivity to various environmental stress conditions. Furthermore, prm1Δ cells show deficiencies in the biosynthesis of chitosan and mannoprotein, which in turn result in impairment of cell wall integrity. Treatment of mice with heat-killed prm1Δ cells was found to facilitate the host immunological defence against infection with wild-type C. neoformans. Further investigation demonstrated that prm1Δ cells strongly promote pulmonary production of interferon-γ, leading to activation of macrophage M1 differentiation and inhibition of M2 polarization. Therefore, our findings suggest that C. neoformans Prm1 may be a viable target for the development of anti-cryptococcosis medications and, cells lacking Prm1 represent a promising candidate for a vaccine.
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Affiliation(s)
- Chao Li
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Yang Meng
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Hailong Li
- NHC Key Laboratory of AIDS Immunology, National Clinical Research Center for Laboratory Medicine, The First Hospital of China Medical University, Shenyang, People’s Republic of China
| | - Wei Du
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Xindi Gao
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Chenhao Suo
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Yiru Gao
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Yue Ni
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Tianshu Sun
- Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, People’s Republic of China
- Department of Scientific Research, Central Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, People’s Republic of China
| | - Sheng Yang
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Tian Lan
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Meiling Xin
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
| | - Chen Ding
- College of Life and Health Sciences, Northeastern University, Shenyang, People’s Republic of China
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Sephton-Clark P, Temfack E, Tenor JL, Toffaletti DL, Loyse A, Molloy SF, Perfect JR, Bicanic T, Harrison TS, Lortholary O, Kouanfack C, Cuomo CA. Genetic diversity and microevolution in clinical Cryptococcus isolates from Cameroon. Med Mycol 2023; 61:myad116. [PMID: 37952096 PMCID: PMC10709296 DOI: 10.1093/mmy/myad116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 11/03/2023] [Accepted: 11/09/2023] [Indexed: 11/14/2023] Open
Abstract
Cryptococcal meningitis is the second most common cause of death in people living with HIV/AIDS, yet we have a limited understanding of how cryptococcal isolates change over the course of infection. Cryptococcal infections are environmentally acquired, and the genetic diversity of these infecting isolates can also be geographically linked. Here, we employ whole genome sequences for 372 clinical Cryptococcus isolates from 341 patients with HIV-associated cryptococcal meningitis obtained via a large clinical trial, across both Malawi and Cameroon, to enable population genetic comparisons of isolates between countries. We see that isolates from Cameroon are highly clonal, when compared to those from Malawi, with differential rates of disruptive variants in genes with roles in DNA binding and energy use. For a subset of patients (22) from Cameroon, we leverage longitudinal sampling, with samples taken at days 7 and 14 post-enrollment, to interrogate the genetic changes that arise over the course of infection, and the genetic diversity of isolates within patients. We see disruptive variants arising over the course of infection in several genes, including the phagocytosis-regulating transcription factor GAT204. In addition, in 13% of patients sampled longitudinally, we see evidence for mixed infections. This approach identifies geographically linked genetic variation, signatures of microevolution, and evidence for mixed infections across a clinical cohort of patients affected by cryptococcal meningitis in Central Africa.
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Affiliation(s)
- Poppy Sephton-Clark
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Elvis Temfack
- Internal Medicine Unit, Douala General Hospital, Douala, Cameroon
- Institut Pasteur, Molecular Mycology Unit, CNRS UMR 2000, Paris, France
| | - Jennifer L Tenor
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Dena L Toffaletti
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Angela Loyse
- Institute of Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group in Infection, St George's University Hospital, London, UK
| | - Síle F Molloy
- Institute of Infection and Immunity, St George's University of London, London, UK
| | - John R Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Tihana Bicanic
- Institute of Infection and Immunity, St George's University of London, London, UK
- Clinical Academic Group in Infection, St George's University Hospital, London, UK
| | - Thomas S Harrison
- Institute of Infection and Immunity, St George's University of London, London, UK
- MRC Centre for Medical Mycology, University of Exeter, Exeter, UK
| | - Olivier Lortholary
- Department of Infectious Diseases and Tropical Medicine, Paris Cité University, Necker-Enfants Malades Hospital, AP-HP, IHU Imagine, Paris, France
- Mycology Department and National Reference Center for Invasive Mycoses and Antifungals, Institut Pasteur, Paris, France
| | - Charles Kouanfack
- Department of Public Health, Faculty of Medicine and Pharmaceutical Sciences, University of Dschang, Dschang, Cameroon
- Day Hospital, Hospital Central Yaoundé, Yaoundé, Cameroon
- Research Center for Emerging and Re-emerging Diseases, Cameroon Baptist Convention Health Services (CBCHS), Yaoundé, Cameroon
| | - Christina A Cuomo
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
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Julian JULIAN, Robiatul ADAWIYAH, Sri WAHDINI. BIOMOLECULAR ACTIVITY OF CRYPTOCOCCUS DURING CRYPTOCOCCOSIS: A REVIEW OF MOLECULAR INTERACTIONS OF CRYPTOCOCCUS WITH HUMAN IMMUNE SYSTEM AND BLOOD-BRAIN-BARRIER. Afr J Infect Dis 2023; 18:11-22. [PMID: 38058414 PMCID: PMC10696652 DOI: 10.21010/ajidv18i1.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 12/08/2023] Open
Abstract
Global mycosis is still a problem. One of these is the cryptococcal disease. A systemic mycosis brought on by Cryptococcus is called cryptococcosis. Host immunological conditions influence infection with Cryptococcosis. When environmental spores are inhaled by the host, the spores get to the lungs, an infection is created. Alveolar macrophages and other immune cells recognize Cryptococcus in the lung. The initial line of defense against pathogens in the phagolysosome is provided by alveolar macrophages found in the lungs. When the immune system is weak, Cryptococcus uses the evasion system as a molecular interaction with the immune system and persists in the lungs without causing any symptoms such as Factor Transcription, Cell masking, N-glycan structure, Extracellular molecule, and Antioxidant system. The evasion mechanism protects and makes Cryptococcus disseminate throughout the other organs, especially CNS. If Cryptococcus escapes against the host immune system, it will disseminate to other organs, especially Cerebrospinal System by Three mechanisms. There are Trojan Horse, Paracellular, and Transcellular interactions with Blood-Brain Barrier. Disease severity is determined by the Interaction between the host's immune system and the fungus.
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Affiliation(s)
- JULIAN Julian
- Master’s Programme in biomedical science, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - ADAWIYAH Robiatul
- Master’s Programme in biomedical science, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
- Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - WAHDINI Sri
- Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
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8
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Ristow LC, Jezewski AJ, Chadwick BJ, Stamnes MA, Lin X, Krysan DJ. Cryptococcus neoformans adapts to the host environment through TOR-mediated remodeling of phospholipid asymmetry. Nat Commun 2023; 14:6587. [PMID: 37852972 PMCID: PMC10584969 DOI: 10.1038/s41467-023-42318-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 10/06/2023] [Indexed: 10/20/2023] Open
Abstract
Cryptococcus spp. are environmental fungi that first must adapt to the host environment before they can cause life-threatening meningitis in immunocompromised patients. Host CO2 concentrations are 100-fold higher than the external environment and strains unable to grow at host CO2 concentrations are not pathogenic. Using a genetic screening and transcriptional profiling approach, we report that the TOR pathway is critical for C. neoformans adaptation to host CO2 partly through Ypk1-dependent remodeling of phosphatidylserine asymmetry at the plasma membrane. We also describe a C. neoformans ABC/PDR transporter (PDR9) that is highly expressed in CO2-sensitive environmental strains, suppresses CO2-induced phosphatidylserine/phospholipid remodeling, and increases susceptibility to host concentrations of CO2. Interestingly, regulation of plasma membrane lipid asymmetry by the TOR-Ypk1 axis is distinct in C. neoformans compared to S. cerevisiae. Finally, host CO2 concentrations suppress the C. neoformans pathways that respond to host temperature (Mpk1) and pH (Rim101), indicating that host adaptation requires a stringent balance among distinct stress responses.
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Affiliation(s)
- Laura C Ristow
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Andrew J Jezewski
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | | | - Mark A Stamnes
- Department of Molecular Physiology and Biophysics, Caver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Xiaorong Lin
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA
| | - Damian J Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Department of Molecular Physiology and Biophysics, Caver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
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Jang EH, Kim JS, Yu SR, Bahn YS. Unraveling Capsule Biosynthesis and Signaling Networks in Cryptococcus neoformans. Microbiol Spectr 2022; 10:e0286622. [PMID: 36287085 PMCID: PMC9769619 DOI: 10.1128/spectrum.02866-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 09/29/2022] [Indexed: 01/09/2023] Open
Abstract
The polysaccharide capsule of Cryptococcus neoformans-an opportunistic basidiomycete pathogen and the major etiological agent of fungal meningoencephalitis-is a key virulence factor that prevents its phagocytosis by host innate immune cells. However, the complex signaling networks for their synthesis and attachment remain elusive. In this study, we systematically analyzed capsule biosynthesis and signaling networks using C. neoformans transcription factor (TF) and kinase mutant libraries under diverse capsule-inducing conditions. We found that deletion of GAT201, YAP1, BZP4, and ADA2 consistently caused capsule production defects in all tested media, indicating that they are capsule-regulating core TFs. Epistatic and expression analyses showed that Yap1 and Ada2 control Gat201 upstream, whereas Bzp4 and Gat201 independently regulate capsule production. Next, we searched for potential upstream kinases and found that mutants lacking PKA1, BUD32, POS5, IRE1, or CDC2801 showed reduced capsule production under all three capsule induction conditions, whereas mutants lacking HOG1 and IRK5 displayed enhanced capsule production. Pka1 and Irk5 controlled the induction of GAT201 and BZP4, respectively, under capsule induction conditions. Finally, we monitored the transcriptome profiles governed by Bzp4, Gat201, and Ada2 under capsule-inducing conditions and demonstrated that these TFs regulate redundant and unique sets of downstream target genes. Bzp4, Ada2, and Gat201 govern capsule formation in C. neoformans by regulating the expression of various capsule biosynthesis genes and chitin/chitosan synthesis genes in a positive and negative manner, respectively. In conclusion, this study provides further insights into the complex regulatory mechanisms of capsule production-related signaling pathways in C. neoformans. IMPORTANCE Over the past decades, human fungal pathogens, including C. neoformans, have emerged as a major public threat since the AIDS pandemic, only to gain more traction in connection to COVID-19. Polysaccharide capsules are rare fungal virulence factors that are critical for protecting C. neoformans from phagocytosis by macrophages. To date, more than 75 proteins involved in capsule synthesis and cell wall attachment have been reported in C. neoformans; however, their complex upstream signaling networks remain elusive. In this study, we demonstrated that Ada2, Yap1, Bzp4, and Gat201 were key capsule-inducing transcriptional regulators. Yap1 and Ada2 function upstream of Gat201, whereas Bzp4 and Gat201 function independently. Genome-wide transcriptome profiling revealed that Bzp4, Gat201, and Ada2 promote capsule production and attachment by positively and negatively regulating genes involved in capsule synthesis and chitin/chitosan synthesis, respectively. Thus, this study provides comprehensive insights into the complex capsule-regulating signaling pathway in C. neoformans.
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Affiliation(s)
- Eun-Ha Jang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Ji-Seok Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Seong-Ryong Yu
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
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10
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Alonso MF, Bain JM, Rudkin FM, Erwig LP, Brown AJ, Gow NA. The nature of the fungal cargo induces significantly different temporal programmes of macrophage phagocytosis. Cell Surf 2022; 8:100082. [PMID: 36299405 PMCID: PMC9589029 DOI: 10.1016/j.tcsw.2022.100082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/12/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
Phagocytosis is an essential component of our immune defence against fungal pathogens. Differences in the dynamics of phagocyte migration, recognition, uptake and phagolysosome maturation are dependent on the characteristics of the fungal cargo, and in particular to differences in cell wall composition and cellular morphology. However, studies that have focused on phagocyte interactions with individual fungal species have not enabled comparisons in the kinetics of these interactions to be made between these different species. We therefore used live cell video microscopy to examine the temporal dynamics of phagocytosis for a range of fungal cargoes by thioglycollate-elicited peritoneal macrophages from C57BL/6 mice. Uniform populations of macrophages were challenged at the same time with yeast cells of Candida albicans, Candida glabrata, Saccharomyces cerevisiae and Cryptococcus neoformans (wild-type and an acapsular mutant, cap59Δ), and spores of Aspergillus fumigatus and Mucor circinelloides to enable standardized comparative interactions to be quantified from different stages of phagocytosis. Differences in the rate of uptake of fungal cells varied by up to 26-fold, whilst differences in time to induce phagosome acidification varied by as much as 29-fold. Heat-killing or opsonizing the fungal targets markedly affected the kinetics of the interaction in a species-specific manner. Fungal and macrophage killing assays further revealed cargo-specific differences in phagocytosis and diversity in fungal evasion mechanisms. Therefore, simultaneous assessment of the interaction of macrophages with different fungal pathogens highlighted major differences in the kinetics and growth responses during fungus-phagocyte interactions that are likely to impact on pathogenesis and virulence.
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Affiliation(s)
- María Fernanda Alonso
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Judith M. Bain
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Fiona M. Rudkin
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Lars P. Erwig
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Alistair J.P. Brown
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
- Medical Research Council Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
| | - Neil A.R. Gow
- The Aberdeen Fungal Group, School of Medicine, Medical Sciences & Nutrition, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
- Medical Research Council Centre for Medical Mycology, University of Exeter, Geoffrey Pope Building, Stocker Road, Exeter EX4 4QD, UK
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11
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Denham ST, Brammer B, Chung KY, Wambaugh MA, Bednarek JM, Guo L, Moreau CT, Brown JCS. A dissemination-prone morphotype enhances extrapulmonary organ entry by Cryptococcus neoformans. Cell Host Microbe 2022; 30:1382-1400.e8. [PMID: 36099922 PMCID: PMC9588642 DOI: 10.1016/j.chom.2022.08.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/01/2022] [Accepted: 08/18/2022] [Indexed: 01/08/2023]
Abstract
Environmental pathogens move from ecological niches to mammalian hosts, requiring adaptation to dramatically different environments. Microbes that disseminate farther, including the fungal meningitis pathogen Cryptococcus neoformans, require additional adaptation to diverse tissues. We demonstrate that the formation of a small C. neoformans morphotype-called "seed" cells due to their colonizing ability-is critical for extrapulmonary organ entry. Seed cells exhibit changes in fungal cell size and surface expression that result in an enhanced macrophage update. Seed cell formation is triggered by environmental factors, including C. neoformans' environmental niche, and pigeon guano with phosphate plays a central role. Seed cells show the enhanced expression of phosphate acquisition genes, and mutants unable to acquire phosphate fail to adopt the seed cell morphotype. Additionally, phosphate can be released by tissue damage, potentially establishing a feed-forward loop of seed cell formation and dissemination. Thus, C. neoformans' size variation represent inducible morphotypes that change host interactions to facilitate microbe spread.
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Affiliation(s)
- Steven T Denham
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Brianna Brammer
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Krystal Y Chung
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Morgan A Wambaugh
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Joseph M Bednarek
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Li Guo
- Molecular Medicine Program, University of Utah, Salt Lake City, UT 84112, USA
| | - Christian T Moreau
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA
| | - Jessica C S Brown
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake City, UT 84112, USA.
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12
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Robbins N, Cowen LE. Genomic Approaches to Antifungal Drug Target Identification and Validation. Annu Rev Microbiol 2022; 76:369-388. [PMID: 35650665 PMCID: PMC10727914 DOI: 10.1146/annurev-micro-041020-094524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The last several decades have witnessed a surge in drug-resistant fungal infections that pose a serious threat to human health. While there is a limited arsenal of drugs that can be used to treat systemic infections, scientific advances have provided renewed optimism for the discovery of novel antifungals. The development of chemical-genomic assays using Saccharomyces cerevisiae has provided powerful methods to identify the mechanism of action of molecules in a living cell. Advances in molecular biology techniques have enabled complementary assays to be developed in fungal pathogens, including Candida albicans and Cryptococcus neoformans. These approaches enable the identification of target genes for drug candidates, as well as genes involved in buffering drug target pathways. Here, we examine yeast chemical-genomic assays and highlight how such resources can be utilized to predict the mechanisms of action of compounds, to study virulence attributes of diverse fungal pathogens, and to bolster the antifungal pipeline.
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Affiliation(s)
- Nicole Robbins
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada;
| | - Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada;
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13
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Regulation of the Leucine Metabolism in Mortierella alpina. J Fungi (Basel) 2022; 8:jof8020196. [PMID: 35205950 PMCID: PMC8880518 DOI: 10.3390/jof8020196] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 12/20/2022] Open
Abstract
The oleaginous fungus Mortierella alpina is a safe source of polyunsaturated fatty acids (PUFA) in industrial food and feed production. Besides PUFA production, pharmaceutically relevant surface-active and antimicrobial oligopeptides were isolated from this basal fungus. Both production of fatty acids and oligopeptides rely on the biosynthesis and high turnover of branched-chain-amino acids (BCAA), especially l-leucine. However, the regulation of BCAA biosynthesis in basal fungi is largely unknown. Here, we report on the regulation of the leucine, isoleucine, and valine metabolism in M. alpina. In contrast to higher fungi, the biosynthetic genes for BCAA are hardly transcriptionally regulated, as shown by qRT-PCR analysis, which suggests a constant production of BCAAs. However, the enzymes of the leucine metabolism are tightly metabolically regulated. Three enzymes of the leucine metabolism were heterologously produced in Escherichia coli, one of which is inhibited by allosteric feedback loops: The key regulator is the α-isopropylmalate synthase LeuA1, which is strongly disabled by l-leucine, α-ketoisocaproate, and propionyl-CoA, the precursor of the odd-chain fatty acid catabolism. Its gene is not related to homologs from higher fungi, but it has been inherited from a phototrophic ancestor by horizontal gene transfer.
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14
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Frerichs AB, Huang M, Ortiz SC, Hull CM. Methods for Manipulating Cryptococcus Spores. J Fungi (Basel) 2021; 8:jof8010004. [PMID: 35049944 PMCID: PMC8779225 DOI: 10.3390/jof8010004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/15/2021] [Accepted: 12/18/2021] [Indexed: 12/02/2022] Open
Abstract
Spores are essential for the long-term survival of many diverse organisms, due to their roles in reproduction and stress resistance. In the environmental human fungal pathogen, Cryptococcus, basidiospores are robust cells with the ability to cause disease in animal models of infection. Here we describe methods for producing and purifying Cryptococcus basidiospores in quantities sufficient for large-scale analyses. The production of high numbers of pure spores has facilitated the development of new assays, including quantitative germination assays, and enabled transcriptomic, proteomic, and virulence studies, leading to discoveries of behaviors and properties unique to spores and spore-mediated disease.
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Affiliation(s)
- Anna B. Frerichs
- Department of Biomolecular Chemistry, School of Medicine and Public Health, Madison, WI 53706, USA; (A.B.F.); (M.H.); (S.C.O.)
| | - Mingwei Huang
- Department of Biomolecular Chemistry, School of Medicine and Public Health, Madison, WI 53706, USA; (A.B.F.); (M.H.); (S.C.O.)
| | - Sébastien C. Ortiz
- Department of Biomolecular Chemistry, School of Medicine and Public Health, Madison, WI 53706, USA; (A.B.F.); (M.H.); (S.C.O.)
| | - Christina M. Hull
- Department of Biomolecular Chemistry, School of Medicine and Public Health, Madison, WI 53706, USA; (A.B.F.); (M.H.); (S.C.O.)
- Department of Medical Microbiology & Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53706, USA
- Correspondence:
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15
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Toh-E A, Ohkusu M, Ishiwada N, Watanabe A, Kamei K. Genetic system underlying responses of Cryptococcus neoformans to cadmium. Curr Genet 2021; 68:125-141. [PMID: 34761291 DOI: 10.1007/s00294-021-01222-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/01/2022]
Abstract
Cryptococcus neoformans, basidiomycetous pathogenic yeast, is basically an environmental fungus and, therefore, challenged by ever changing environments. In this study, we focused on how C. neoformans responds to stress caused by cadmium that is one of high-risk pollutants. By tracking phenotypes of the resistance or sensitivity to cadmium, we undertook forward and reverse genetic studies to identify genes involved in cadmium metabolism in C. neoformans. We found that the main route of Cd2+ influx is through Mn2+ ion transporter, Smf1, which is an ortholog of Nramp (natural resistance-associated macrophage protein 1) of mouse. We found that serotype A strains are generally more resistant to cadmium than serotype D strains and that cadmium resistance of H99, a representative of serotype A strains, was found to be due to a partial defect in SMF1. We found that calcium channel has a subsidiary role for cadmium uptake. We also showed that Pca1 (P-type-ATPase) functions as an extrusion pump for cadmium. We examined the effects of some metals on cadmium toxicity and suggested (i) that Ca2+ and Zn2+ could exert their protective function against Cd2+ via restoring cadmium-inhibited cellular processes and (ii) that Mg2+ and Mn2+ could have antagonistic roles in an unknown Smf1-independent Cd2+ uptake system. We proposed a model for Cd2+-response of C. neoformans, which will serve as a platform for understanding how this organism copes with the toxic metal.
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Affiliation(s)
- Akio Toh-E
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chiba, 260-8673, Japan.
| | - Misako Ohkusu
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chiba, 260-8673, Japan
| | - Naruhiko Ishiwada
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chiba, 260-8673, Japan
| | - Akira Watanabe
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chiba, 260-8673, Japan
| | - Katsuhiko Kamei
- Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chiba, 260-8673, Japan
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16
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Rizzo J, Wong SSW, Gazi AD, Moyrand F, Chaze T, Commere P, Novault S, Matondo M, Péhau‐Arnaudet G, Reis FCG, Vos M, Alves LR, May RC, Nimrichter L, Rodrigues ML, Aimanianda V, Janbon G. Cryptococcus extracellular vesicles properties and their use as vaccine platforms. J Extracell Vesicles 2021; 10:e12129. [PMID: 34377375 PMCID: PMC8329992 DOI: 10.1002/jev2.12129] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 07/02/2021] [Accepted: 07/09/2021] [Indexed: 12/12/2022] Open
Abstract
Whereas extracellular vesicle (EV) research has become commonplace in different biomedical fields, this field of research is still in its infancy in mycology. Here we provide a robust set of data regarding the structural and compositional aspects of EVs isolated from the fungal pathogenic species Cryptococcus neoformans, C. deneoformans and C. deuterogattii. Using cutting-edge methodological approaches including cryogenic electron microscopy and cryogenic electron tomography, proteomics, and flow cytometry, we revisited cryptococcal EV features and suggest a new EV structural model, in which the vesicular lipid bilayer is covered by mannoprotein-based fibrillar decoration, bearing the capsule polysaccharide as its outer layer. About 10% of the EV population is devoid of fibrillar decoration, adding another aspect to EV diversity. By analysing EV protein cargo from the three species, we characterized the typical Cryptococcus EV proteome. It contains several membrane-bound protein families, including some Tsh proteins bearing a SUR7/PalI motif. The presence of known protective antigens on the surface of Cryptococcus EVs, resembling the morphology of encapsulated virus structures, suggested their potential as a vaccine. Indeed, mice immunized with EVs obtained from an acapsular C. neoformans mutant strain rendered a strong antibody response in mice and significantly prolonged their survival upon C. neoformans infection.
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Affiliation(s)
- Juliana Rizzo
- Unité Biologie des ARN des Pathogènes FongiquesDépartement de Mycologie, Institut Pasteur, F‐75015ParisFrance
| | - Sarah Sze Wah Wong
- Unité Mycologie Moléculaire, CNRS UMR2000Département de Mycologie, Institut Pasteur, F‐75015ParisFrance
| | - Anastasia D. Gazi
- Ultrastructural Bio‐Imaging, UTechS UBI, CNRS UMR 3528Département de Biologie cellulaire et infection, Institut Pasteur, F‐75015ParisFrance
| | - Frédérique Moyrand
- Unité Biologie des ARN des Pathogènes FongiquesDépartement de Mycologie, Institut Pasteur, F‐75015ParisFrance
| | - Thibault Chaze
- Plateforme Protéomique, Unité de Spectrométrie de Masse pour la Biologie (MSBio), CNRS UMR 2000Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, F‐75015ParisFrance
| | - Pierre‐Henri Commere
- Cytometry and BiomarkersCentre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, F‐75015ParisFrance
| | - Sophie Novault
- Cytometry and BiomarkersCentre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, F‐75015ParisFrance
| | - Mariette Matondo
- Plateforme Protéomique, Unité de Spectrométrie de Masse pour la Biologie (MSBio), CNRS UMR 2000Centre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, F‐75015ParisFrance
| | - Gérard Péhau‐Arnaudet
- Ultrastructural Bio‐Imaging, UTechS UBI, CNRS UMR 3528Département de Biologie cellulaire et infection, Institut Pasteur, F‐75015ParisFrance
| | - Flavia C. G. Reis
- Instituto Carlos ChagasFundação Oswaldo Cruz (FIOCRUZ)CuritibaBrazil
- Centro de Desenvolvimento Tecnologico em Saude (CDTS‐Fiocruz)São PauloBrazil
| | - Matthijn Vos
- NanoImaging Core FacilityCentre de Ressources et Recherches Technologiques (C2RT), Institut Pasteur, F‐75015ParisFrance
| | | | - Robin C. May
- Institute of Microbiology and Infection and School of BiosciencesUniversity of BirminghamBirminghamB15 2TTUK
| | - Leonardo Nimrichter
- Instituto de Microbiologia Paulo de Góes (IMPG)Universidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Marcio L. Rodrigues
- Instituto Carlos ChagasFundação Oswaldo Cruz (FIOCRUZ)CuritibaBrazil
- Instituto de Microbiologia Paulo de Góes (IMPG)Universidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Vishukumar Aimanianda
- Unité Mycologie Moléculaire, CNRS UMR2000Département de Mycologie, Institut Pasteur, F‐75015ParisFrance
| | - Guilhem Janbon
- Unité Biologie des ARN des Pathogènes FongiquesDépartement de Mycologie, Institut Pasteur, F‐75015ParisFrance
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17
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The Transcription Factor Pdr802 Regulates Titan Cell Formation and Pathogenicity of Cryptococcus neoformans. mBio 2021; 12:mBio.03457-20. [PMID: 33688010 PMCID: PMC8092302 DOI: 10.1128/mbio.03457-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The pathogenic yeast Cryptococcus neoformans presents a worldwide threat to human health, especially in the context of immunocompromise, and current antifungal therapy is hindered by cost, limited availability, and inadequate efficacy. After the infectious particle is inhaled, C. neoformans initiates a complex transcriptional program that integrates cellular responses and enables adaptation to the host lung environment. Cryptococcus neoformans is a ubiquitous, opportunistic fungal pathogen that kills almost 200,000 people worldwide each year. It is acquired when mammalian hosts inhale the infectious propagules; these are deposited in the lung and, in the context of immunocompromise, may disseminate to the brain and cause lethal meningoencephalitis. Once inside the host, C. neoformans undergoes a variety of adaptive processes, including secretion of virulence factors, expansion of a polysaccharide capsule that impedes phagocytosis, and the production of giant (Titan) cells. The transcription factor Pdr802 is one regulator of these responses to the host environment. Expression of the corresponding gene is highly induced under host-like conditions in vitro and is critical for C. neoformans dissemination and virulence in a mouse model of infection. Direct targets of Pdr802 include the quorum sensing proteins Pqp1, Opt1, and Liv3; the transcription factors Stb4, Zfc3, and Bzp4, which regulate cryptococcal brain infectivity and capsule thickness; the calcineurin targets Had1 and Crz1, important for cell wall remodeling and C. neoformans virulence; and additional genes related to resistance to host temperature and oxidative stress, and to urease activity. Notably, cryptococci engineered to lack Pdr802 showed a dramatic increase in Titan cells, which are not phagocytosed and have diminished ability to directly cross biological barriers. This explains the limited dissemination of pdr802 mutant cells to the central nervous system and the consequently reduced virulence of this strain. The role of Pdr802 as a negative regulator of Titan cell formation is thus critical for cryptococcal pathogenicity.
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18
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Gaylord EA, Choy HL, Doering TL. Dangerous Liaisons: Interactions of Cryptococcus neoformans with Host Phagocytes. Pathogens 2020; 9:E891. [PMID: 33121050 PMCID: PMC7692806 DOI: 10.3390/pathogens9110891] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 10/22/2020] [Accepted: 10/25/2020] [Indexed: 02/07/2023] Open
Abstract
Cryptococcus neoformans is an opportunistic fungal pathogen and a leading cause of death in immunocompromised individuals. The interactions of this yeast with host phagocytes are critical to disease outcome, and C. neoformans is equipped with an array of factors to modulate these processes. Cryptococcal infection begins with the deposition of infectious particles into the lungs, where the fungal cells deploy various antiphagocytic factors to resist internalization by host cells. If the cryptococci are still engulfed, they can survive and proliferate within host cells by modulating the phagolysosome environment in which they reside. Lastly, cryptococcal cells may escape from phagocytes by host cell lysis, nonlytic exocytosis, or lateral cell-to-cell transfer. The interactions between C. neoformans and host phagocytes also influence the dissemination of this pathogen to the brain, where it may cross the blood-brain barrier and cause an often-fatal meningoencephalitis. In this review, we highlight key cryptococcal factors involved in various stages of cryptococcal-host interaction and pathogenesis.
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Affiliation(s)
| | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; (E.A.G.); (H.L.C.)
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19
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Ueno K, Yanagihara N, Otani Y, Shimizu K, Kinjo Y, Miyazaki Y. Neutrophil-mediated antifungal activity against highly virulent Cryptococcus gattii strain R265. Med Mycol 2020; 57:1046-1054. [PMID: 30668754 DOI: 10.1093/mmy/myy153] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 01/08/2023] Open
Abstract
Vaccine-induced immune responses, including neutrophil, macrophage, and T-cell responses, ameliorate cryptococcosis caused by Cryptococcus gattii. However, whether neutrophils can exert fungicidal activity against C. gattii remains to be elucidated. Therefore, in this study, we investigated the neutrophil-mediated fungicidal effect against C. gattii R265 in vitro and compared it to the related fungal pathogen, Cryptococcus neoformans standard strain H99. We found that neutrophils recognized, phagocytosed, and killed C. gattii R265 in the presence of fresh mouse serum. This antifungal effect required phagocytosis and serine protease activity but not nicotinamide adenine dinucleotide phosphate oxidase activity. We also demonstrated that C. gattii R265 was more resistant to oxidative and nitrosative stress than C. neoformans H99. Together, these findings indicate that neutrophils can exert fungicidal activity against highly virulent C. gattii, at least under in vitro conditions.
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Affiliation(s)
- Keigo Ueno
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Nao Yanagihara
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.,Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Yoshiko Otani
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.,Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Kiminori Shimizu
- Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Yuki Kinjo
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.,Department of Bacteriology, The Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan.,Jikei Center for Biofilm Science and Technology, The Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-ku, Tokyo 105-8461, Japan
| | - Yoshitsugu Miyazaki
- Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
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20
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De Lerma Barbaro A, Gariboldi MB, Mastore M, Brivio MF, Giovannardi S. In Vivo Effects of A Pro-PO System Inhibitor on the Phagocytosis of Xenorhabdus Nematophila in Galleria Mellonella Larvae. INSECTS 2019; 10:E263. [PMID: 31443446 PMCID: PMC6780223 DOI: 10.3390/insects10090263] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/03/2019] [Accepted: 08/16/2019] [Indexed: 12/21/2022]
Abstract
Xenorhabdus nematophila is a Gram-negative bacterium symbiont of the entomopathogen nematode Steinernema carpocapsae whose immunosuppressive properties over host's immune response have been thoroughly investigated. In particular, live X. nematophila actively impairs phagocytosis in host's hemocytes through the secretion of inhibitors of eicosanoids synthesis. In this article we have investigated the cell surface structural features of X. nematophila responsible for the elusion from phagocytosis. To this end we have studied the uptake of heat-killed (hk), fluorescein isothiocyanate (FITC)-labeled X. nematophila by phagocytes from both a host insect and a mammalian species. In vitro dead X. nematophila passively resists engulfment by insect hemocytes without impairing the phagocytosis machinery whereas, unexpectedly, in vivo a significant phagocytosis of dead X. nematophila was observed. X. nematophila in vivo phagocytosis was increased by the co-injection of the specific inhibitor of pro-phenoloxidase (PO) system phenylthiourea (PTU), even if these effects were not observed in in vitro tests. Furthermore, biochemical modifications of X. nematophila cell wall implement in vivo phagocytosis, suggesting that this bacterium avoid phagocytosis because the ligand of phagocytic receptors is somehow buried or disguised in the cell wall. Finally, dead X. nematophila escapes engulfment even by human phagocytes suggesting that X. nematophila could be a useful model to investigate escape from phagocytosis by mammalian macrophages.
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Affiliation(s)
- Andrea De Lerma Barbaro
- Laboratory of Comparative Physiopathology, Department of Biotechnology and Life Sciences, University of Insubria, 21052 Busto Arsizio (Varese), Italy
| | - Marzia B Gariboldi
- Laboratory of Anticancer Pharmacology, Department of Biotechnology and Life Sciences, University of Insubria, 21052 Busto Arsizio (Varese), Italy
| | - Maristella Mastore
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy
| | - Maurizio F Brivio
- Laboratory of Comparative Immunology and Parasitology, Department of Theoretical and Applied Sciences, University of Insubria, 21100 Varese, Italy
| | - Stefano Giovannardi
- Laboratory of Comparative Physiopathology, Department of Biotechnology and Life Sciences, University of Insubria, 21052 Busto Arsizio (Varese), Italy.
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21
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Unveil the transcriptional landscape at the Cryptococcus-host axis in mice and nonhuman primates. PLoS Negl Trop Dis 2019; 13:e0007566. [PMID: 31329596 PMCID: PMC6675133 DOI: 10.1371/journal.pntd.0007566] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 08/01/2019] [Accepted: 06/20/2019] [Indexed: 12/17/2022] Open
Abstract
Pathogens and hosts require rapid modulation of virulence and defense mechanisms at the infection axis, but monitoring such modulations is challenging. In studying the human fungal pathogen Cryptococcus neoformans, mouse and rabbit infection models are often employed to shed light on the disease mechanisms but that may not be clinically relevant. In this study, we developed an animal infection model using the non-human primate cynomolgus monkey Macaca fascicularis. In addition, we systematically profiled and compared transcriptional responses between the infected mice and the cynomolgus monkey, using simultaneous or dual RNA next-generation sequencing. We demonstrated that there are shared but distinct transcriptional profiles between the two models following C. neoformans infection. Specifically, genes involved in immune and inflammatory responses are all upregulated. Osteoclastogenesis and insulin signaling are also significantly co-regulated in both models and disrupting an osteoclastogenesis-associated gene (OC-STAMP) or the insulin-signaling process significantly altered the host tolerance to C. neoformans. Moreover, C. neoformans was shown to activate metal sequestration, dampen the sugar metabolism, and control cell morphology during infection. Taking together, we described the development of a non-human primate model of cryptococcosis that allowed us to perform an in-depth analysis and comparison of transcriptome profiles during infections of two animal models and conceptually identify host genes important in disease responses. This study provides new insights in understanding fungal pathogenesis mechanisms that potentially facilitate the identification of novel drug targets for the treatment of cryptococcal infection. The host-pathogen interaction is highly dynamic and tightly regulated, and yet is difficult to monitor. Traditional investigations provide valuable information for the understanding of pathogenic microbial biology but are time-consuming and often neglect the host immune responses. In addition, current animal models for studying pathogenic fungi are limited in mimicking the responses from humans. The development of a new Cryptococcus neoformans infection model using nonhuman primates and the utilization of simultaneous RNA sequencing analysis provide fast and clinically relevant research data allowing the identification of novel critical players from both the invading fungus and the host. The data from the current study would not only help to decipher disease mechanisms but also promote the discovery of novel antifungal drug targets.
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Camacho E, Vij R, Chrissian C, Prados-Rosales R, Gil D, O'Meally RN, Cordero RJB, Cole RN, McCaffery JM, Stark RE, Casadevall A. The structural unit of melanin in the cell wall of the fungal pathogen Cryptococcus neoformans. J Biol Chem 2019; 294:10471-10489. [PMID: 31118223 PMCID: PMC6615676 DOI: 10.1074/jbc.ra119.008684] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/19/2019] [Indexed: 11/06/2022] Open
Abstract
Melanins are synthesized macromolecules that are found in all biological kingdoms. These pigments have a myriad of roles that range from microbial virulence to key components of the innate immune response in invertebrates. Melanins also exhibit unique properties with potential applications in physics and material sciences, ranging from electrical batteries to novel therapeutics. In the fungi, melanins, such as eumelanins, are components of the cell wall that provide protection against biotic and abiotic elements. Elucidation of the smallest fungal cell wall-associated melanin unit that serves as a building block is critical to understand the architecture of these polymers, its interaction with surrounding components, and their functional versatility. In this study, we used isopycnic gradient sedimentation, NMR, EPR, high-resolution microscopy, and proteomics to analyze the melanin in the cell wall of the human pathogenic fungus Cryptococcus neoformans We observed that melanin is assembled into the cryptococcal cell wall in spherical structures ∼200 nm in diameter, termed melanin granules, which are in turn composed of nanospheres ∼30 nm in diameter, termed fungal melanosomes. We noted that melanin granules are closely associated with proteins that may play critical roles in the fungal melanogenesis and the supramolecular structure of this polymer. Using this structural information, we propose a model for C. neoformans' melanization that is similar to the process used in animal melanization and is consistent with the phylogenetic relatedness of the fungal and animal kingdoms.
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Affiliation(s)
- Emma Camacho
- From the Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Raghav Vij
- From the Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Christine Chrissian
- the Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, New York, New York 10031, the City University of New York
- Ph.D. Programs in Biochemistry and
| | - Rafael Prados-Rosales
- the Department of Microbiology and Immunology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461
- the CIC bioGUNE, 48160 Derio, Vizcaya, Spain
- the Department of Preventive Medicine and Public Health and Microbiology, Autonoma University of Madrid, 28049 Madrid, Spain
| | - David Gil
- the CIC bioGUNE, 48160 Derio, Vizcaya, Spain
| | - Robert N O'Meally
- the Johns Hopkins Mass Spectrometry and Proteomic Facility, The Johns Hopkins University, Baltimore, Maryland 21205, and
| | - Radames J B Cordero
- From the Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Robert N Cole
- the Johns Hopkins Mass Spectrometry and Proteomic Facility, The Johns Hopkins University, Baltimore, Maryland 21205, and
| | - J Michael McCaffery
- the Integrated Imaging Center, Department of Biology, Engineering in Oncology Center, and Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, Maryland 21218
| | - Ruth E Stark
- the Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, New York, New York 10031, the City University of New York
- Ph.D. Programs in Biochemistry and
- Chemistry, New York, New York 10016
| | - Arturo Casadevall
- From the Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205,
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Studying fungal pathogens of humans and fungal infections: fungal diversity and diversity of approaches. Microbes Infect 2019; 21:237-245. [PMID: 31255676 DOI: 10.1016/j.micinf.2019.06.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/26/2022]
Abstract
Seminal work by Louis Pasteur revealed the contribution of fungi - yeasts and microsporidia to agroindustry and disease in animals, respectively. More than 150 years later, the impact of fungi on human health and beyond is an ever-increasing issue, although often underestimated. Recent studies estimate that fungal infections, especially those caused by Candida, Cryptococcus and Aspergillus species, kill more than one million people annually. Indeed, these neglected infections are in general very difficult to cure and the associated mortality remains very high even when antifungal treatments exist. The development of new antifungals and diagnostic tools that are both necessary to fight fungal diseases efficiently, requires greater insights in the biology of the fungal pathogens of humans in the context of the infection, on their epidemiology, and on their role in the human mycobiota. We also need a better understanding of the host immune responses to fungal pathogens as well as the genetic basis for the increased sensitivity of some individuals to fungal infections. Here, we highlight some recent progress made in these different areas of research, in particular based on work conducted in our own laboratories. These progresses should lay the ground for better management of fungal infections, as they provide opportunities for better diagnostic, vaccination, the development of classical antifungals but also strategies for targeting virulence factors or the host.
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de Oliveira HC, Trevijano-Contador N, Garcia-Rodas R. Cryptococcal Pathogenicity and Morphogenesis. CURRENT FUNGAL INFECTION REPORTS 2019. [DOI: 10.1007/s12281-019-00340-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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25
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Studying fungal pathogens of humans and fungal infections: fungal diversity and diversity of approaches. Genes Immun 2019; 20:403-414. [PMID: 31019254 DOI: 10.1038/s41435-019-0071-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/24/2022]
Abstract
Seminal work by Louis Pasteur revealed the contribution of fungi-yeasts and microsporidia to agroindustry and disease in animals, respectively. More than 150 years later, the impact of fungi on human health and beyond is an ever-increasing issue, although often underestimated. Recent studies estimate that fungal infections, especially those caused by Candida, Cryptococcus and Aspergillus species, kill more than one million people annually. Indeed, these neglected infections are in general very difficult to cure and the associated mortality remains very high even when antifungal treatments exist. The development of new antifungals and diagnostic tools that are both necessary to fight fungal diseases efficiently, requires greater insights in the biology of the fungal pathogens of humans in the context of the infection, on their epidemiology, and on their role in the human mycobiota. We also need a better understanding of the host immune responses to fungal pathogens as well as the genetic basis for the increased sensitivity of some individuals to fungal infections. Here, we highlight some recent progress made in these different areas of research, in particular based on work conducted in our own laboratories. These progress should lay the ground for better management of fungal infections, as they provide opportunities for better diagnostic, vaccination, the development of classical antifungals but also strategies for targeting virulence factors or the host.
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26
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Shourian M, Qureshi ST. Resistance and Tolerance to Cryptococcal Infection: An Intricate Balance That Controls the Development of Disease. Front Immunol 2019; 10:66. [PMID: 30761136 PMCID: PMC6361814 DOI: 10.3389/fimmu.2019.00066] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 01/11/2019] [Indexed: 12/25/2022] Open
Abstract
Cryptococcus neoformans is a ubiquitous environmental yeast and a leading cause of invasive fungal infection in humans. The most recent estimate of global disease burden includes over 200,000 cases of cryptococcal meningitis each year. Cryptococcus neoformans expresses several virulence factors that may have originally evolved to protect against environmental threats, and human infection may be an unintended consequence of these acquired defenses. Traditionally, C. neoformans has been viewed as a purely opportunistic pathogen that targets severely immune compromised hosts; however, during the past decade the spectrum of susceptible individuals has grown considerably. In addition, the closely related strain Cryptococcus gattii has recently emerged in North America and preferentially targets individuals with intact immunity. In parallel to the changing epidemiology of cryptococcosis, an increasing role for host immunity in the pathogenesis of severe disease has been elucidated. Initially, the HIV/AIDS epidemic revealed the capacity of C. neoformans to cause host damage in the absence of adaptive immunity. Subsequently, the development and clinical implementation of highly active antiretroviral treatment (HAART) led to recognition of an immune reconstitution inflammatory syndrome (IRIS) in a subset of HIV+ individuals, demonstrating the pathological role of host immunity in disease. A post-infectious inflammatory syndrome (PIIRS) characterized by abnormal T cell-macrophage activation has also been documented in HIV-negative individuals following antifungal therapy. These novel clinical conditions illustrate the highly complex host-pathogen relationship that underlies severe cryptococcal disease and the intricate balance between tolerance and resistance that is necessary for effective resolution. In this article, we will review current knowledge of the interactions between cryptococci and mammalian hosts that result in a tolerant phenotype. Future investigations in this area have potential for translation into improved therapies for affected individuals.
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Affiliation(s)
- Mitra Shourian
- Translational Research in Respiratory Diseases Program, Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada
| | - Salman T Qureshi
- Translational Research in Respiratory Diseases Program, Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, QC, Canada.,Division of Experimental Medicine, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada
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27
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Motaung TE. Cryptococcus neoformans mutant screening: a genome-scale's worth of function discovery. FUNGAL BIOL REV 2018. [DOI: 10.1016/j.fbr.2018.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Garcia-Santamarina S, Festa RA, Smith AD, Yu CH, Probst C, Ding C, Homer CM, Yin J, Noonan JP, Madhani H, Perfect JR, Thiele DJ. Genome-wide analysis of the regulation of Cu metabolism in Cryptococcus neoformans. Mol Microbiol 2018; 108:473-494. [PMID: 29608794 PMCID: PMC5980777 DOI: 10.1111/mmi.13960] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2018] [Indexed: 12/13/2022]
Abstract
The ability of the human fungal pathogen Cryptococcus neoformans to adapt to variable copper (Cu) environments within the host is key for successful dissemination and colonization. During pulmonary infection, host alveolar macrophages compartmentalize Cu into the phagosome and C. neoformans Cu-detoxifying metallothioneins, MT1 and MT2, are required for survival of the pathogen. In contrast, during brain colonization the C. neoformans Cu+ importers Ctr1 and Ctr4 are required for virulence. Central for the regulation and expression of both the Cu detoxifying MT1/2 and the Cu acquisition Ctr1/4 proteins is the Cu-metalloregulatory transcription factor Cuf1, an established C. neoformans virulence factor. Due to the importance of the distinct C. neoformans Cu homeostasis mechanisms during host colonization and virulence, and to the central role of Cuf1 in regulating Cu homeostasis, we performed a combination of RNA-Seq and ChIP-Seq experiments to identify differentially transcribed genes between conditions of high and low Cu. We demonstrate that the transcriptional regulation exerted by Cuf1 is intrinsically complex and that Cuf1 also functions as a transcriptional repressor. The Cu- and Cuf1-dependent regulon in C. neoformans reveals new adaptive mechanisms for Cu homeostasis in this pathogenic fungus and identifies potential new pathogen-specific targets for therapeutic intervention in fungal infections.
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Affiliation(s)
- Sarela Garcia-Santamarina
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Richard A. Festa
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Aaron D. Smith
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Chen-Hsin Yu
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Corinna Probst
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Chen Ding
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Christina M. Homer
- Department of Biochemistry and Biophysics, UCSF, San Francisco, California, USA
| | - Jun Yin
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - James P. Noonan
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Hiten Madhani
- Department of Biochemistry and Biophysics, UCSF, San Francisco, California, USA
| | - John R. Perfect
- Division of Infectious Diseases, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Dennis J. Thiele
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina, USA
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Mechanisms of Pulmonary Escape and Dissemination by Cryptococcus neoformans. J Fungi (Basel) 2018; 4:jof4010025. [PMID: 29463005 PMCID: PMC5872328 DOI: 10.3390/jof4010025] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/09/2018] [Accepted: 02/16/2018] [Indexed: 12/15/2022] Open
Abstract
Cryptococcus neoformans is a common environmental saprophyte and human fungal pathogen that primarily causes disease in immunocompromised individuals. Similar to many environmentally acquired human fungal pathogens, C. neoformans initiates infection in the lungs. However, the main driver of mortality is invasive cryptococcosis leading to fungal meningitis. After C. neoformans gains a foothold in the lungs, a critical early step in invasion is transversal of the respiratory epithelium. In this review, we summarize current knowledge relating to pulmonary escape. We focus on fungal factors that allow C. neoformans to disseminate from the lungs via intracellular and extracellular routes.
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Abstract
Fungi must meet four criteria to infect humans: growth at human body temperatures, circumvention or penetration of surface barriers, lysis and absorption of tissue, and resistance to immune defenses, including elevated body temperatures. Morphogenesis between small round, detachable cells and long, connected cells is the mechanism by which fungi solve problems of locomotion around or through host barriers. Secretion of lytic enzymes, and uptake systems for the released nutrients, are necessary if a fungus is to nutritionally utilize human tissue. Last, the potent human immune system evolved in the interaction with potential fungal pathogens, so few fungi meet all four conditions for a healthy human host. Paradoxically, the advances of modern medicine have made millions of people newly susceptible to fungal infections by disrupting immune defenses. This article explores how different members of four fungal phyla use different strategies to fulfill the four criteria to infect humans: the Entomophthorales, the Mucorales, the Ascomycota, and the Basidiomycota. Unique traits confer human pathogenic potential on various important members of these phyla: pathogenic Onygenales comprising thermal dimorphs such as Histoplasma and Coccidioides; the Cryptococcus spp. that infect immunocompromised as well as healthy humans; and important pathogens of immunocompromised patients-Candida, Pneumocystis, and Aspergillus spp. Also discussed are agents of neglected tropical diseases important in global health such as mycetoma and paracoccidiomycosis and common pathogens rarely implicated in serious illness such as dermatophytes. Commensalism is considered, as well as parasitism, in shaping genomes and physiological systems of hosts and fungi during evolution.
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Ding H, Mayer FL, Sánchez-León E, de S Araújo GR, Frases S, Kronstad JW. Networks of fibers and factors: regulation of capsule formation in Cryptococcus neoformans. F1000Res 2016; 5. [PMID: 27516877 PMCID: PMC4979528 DOI: 10.12688/f1000research.8854.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/12/2016] [Indexed: 12/15/2022] Open
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.
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Affiliation(s)
- Hao Ding
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - François L Mayer
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Eddy Sánchez-León
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada
| | - Glauber R de S Araújo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, Canada.,Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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Intracellular Action of a Secreted Peptide Required for Fungal Virulence. Cell Host Microbe 2016; 19:849-64. [PMID: 27212659 DOI: 10.1016/j.chom.2016.05.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 12/24/2015] [Accepted: 04/28/2016] [Indexed: 01/02/2023]
Abstract
Quorum sensing (QS) is a bacterial communication mechanism in which secreted signaling molecules impact population function and gene expression. QS-like phenomena have been reported in eukaryotes with largely unknown contributing molecules, functions, and mechanisms. We identify Qsp1, a secreted peptide, as a central signaling molecule that regulates virulence in the fungal pathogen Cryptococcus neoformans. QSP1 is a direct target of three transcription factors required for virulence, and qsp1Δ mutants exhibit attenuated infection, slowed tissue accumulation, and greater control by primary macrophages. Qsp1 mediates autoregulatory signaling that modulates secreted protease activity and promotes cell wall function at high cell densities. Peptide production requires release from a secreted precursor, proQsp1, by a cell-associated protease, Pqp1. Qsp1 sensing requires an oligopeptide transporter, Opt1, and remarkably, cytoplasmic expression of mature Qsp1 complements multiple phenotypes of qsp1Δ. Thus, C. neoformans produces an autoregulatory peptide that matures extracellularly but functions intracellularly to regulate virulence.
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Computational Analysis Reveals a Key Regulator of Cryptococcal Virulence and Determinant of Host Response. mBio 2016; 7:e00313-16. [PMID: 27094327 PMCID: PMC4850258 DOI: 10.1128/mbio.00313-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Cryptococcus neoformans is a ubiquitous, opportunistic fungal pathogen that kills over 600,000 people annually. Here, we report integrated computational and experimental investigations of the role and mechanisms of transcriptional regulation in cryptococcal infection. Major cryptococcal virulence traits include melanin production and the development of a large polysaccharide capsule upon host entry; shed capsule polysaccharides also impair host defenses. We found that both transcription and translation are required for capsule growth and that Usv101 is a master regulator of pathogenesis, regulating melanin production, capsule growth, and capsule shedding. It does this by directly regulating genes encoding glycoactive enzymes and genes encoding three other transcription factors that are essential for capsule growth: GAT201, RIM101, and SP1. Murine infection with cryptococci lacking Usv101 significantly alters the kinetics and pathogenesis of disease, with extended survival and, unexpectedly, death by pneumonia rather than meningitis. Our approaches and findings will inform studies of other pathogenic microbes. Cryptococcus neoformans causes fatal meningitis in immunocompromised individuals, mainly HIV positive, killing over 600,000 each year. A unique feature of this yeast, which makes it particularly virulent, is its polysaccharide capsule; this structure impedes host efforts to combat infection. Capsule size and structure respond to environmental conditions, such as those encountered in an infected host. We have combined computational and experimental tools to elucidate capsule regulation, which we show primarily occurs at the transcriptional level. We also demonstrate that loss of a novel transcription factor alters virulence factor expression and host cell interactions, changing the lethal condition from meningitis to pneumonia with an exacerbated host response. We further demonstrate the relevant targets of regulation and kinetically map key regulatory and host interactions. Our work elucidates mechanisms of capsule regulation, provides methods and resources to the research community, and demonstrates an altered pathogenic outcome that resembles some human conditions.
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Rathore SS, Raman T, Ramakrishnan J. Magnesium Ion Acts as a Signal for Capsule Induction in Cryptococcus neoformans. Front Microbiol 2016; 7:325. [PMID: 27014245 PMCID: PMC4791529 DOI: 10.3389/fmicb.2016.00325] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 02/29/2016] [Indexed: 12/24/2022] Open
Abstract
Cryptococcal meningitis caused by Cryptococcus neoformans, is a common opportunistic neural infection in immunocompromised individuals. Cryptococcus meningitis is associated with fungal burden with larger capsule size in cerebrospinal fluid (CSF). To understand the role of CSF constituents in capsule enlargement, we have evaluated the effect of artificial CSF on capsule induction in comparison with various other capsule inducing media. Two different strains of C. neoformans, an environmental and a clinical isolates were used in the present study. While comparing the various capsule inducing media for the two different strains of C. neoformans, it was observed that the capsule growth was significantly increased when grown in artificial CSF at pH 5.5, temperature 34°C for ATCC C. neoformans and 37°C for Clinical C. neoformans and with an incubation period of 72 h. In addition, artificial CSF supports biofilm formation in C. neoformans. While investigating the individual components of artificial CSF, we found that Mg2+ ions influence the capsule growth in both environmental and clinical strains of C. neoformans. To confirm our results we studied the expression of four major CAP genes namely, CAP10, CAP59, CAP60, and CAP64 in various capsule inducing media and in different concentrations of Mg2+ and Ca2+. Our results on gene expression suggest that, Mg2+ does have an effect on CAP gene expression, which are important for capsule biosynthesis and virulence. Our findings on the role of Mg2+ ion as a signal for capsule induction will promote a way to elucidate the control mechanisms for capsule biosynthesis in C. neoformans.
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Affiliation(s)
- Sudarshan S Rathore
- Centre for Research in Infectious Diseases, School of Chemical and Biotechnology, Shanmugha Arts, Science, Technology & Research Academy University Thanjavur, India
| | - Thiagarajan Raman
- Centre for Research in Infectious Diseases, School of Chemical and Biotechnology, Shanmugha Arts, Science, Technology & Research Academy University Thanjavur, India
| | - Jayapradha Ramakrishnan
- Centre for Research in Infectious Diseases, School of Chemical and Biotechnology, Shanmugha Arts, Science, Technology & Research Academy University Thanjavur, India
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Rathore SS, Ramamurthy V, Allen S, Selva Ganesan S, Ramakrishnan J. Novel approach of adaptive laboratory evolution: triggers defense molecules in Streptomyces sp. against targeted pathogen. RSC Adv 2016. [DOI: 10.1039/c6ra15952d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Adaptive laboratory evolution by competition-based co-culture: triggers and enhance specific bioactive molecules against targeted pathogen.
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Affiliation(s)
- Sudarshan Singh Rathore
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India – 613401
| | - Vigneshwari Ramamurthy
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India – 613401
| | - Sally Allen
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India – 613401
| | - S. Selva Ganesan
- Department of Chemistry
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur-613401
- India
| | - Jayapradha Ramakrishnan
- Centre for Research in Infectious Diseases (CRID)
- School of Chemical and Biotechnology
- SASTRA University
- Thanjavur
- India – 613401
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Geddes JMH, Croll D, Caza M, Stoynov N, Foster LJ, Kronstad JW. Secretome profiling of Cryptococcus neoformans reveals regulation of a subset of virulence-associated proteins and potential biomarkers by protein kinase A. BMC Microbiol 2015; 15:206. [PMID: 26453029 PMCID: PMC4600298 DOI: 10.1186/s12866-015-0532-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 09/25/2015] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The pathogenic yeast Cryptococcus neoformans causes life-threatening meningoencephalitis in individuals suffering from HIV/AIDS. The cyclic-AMP/protein kinase A (PKA) signal transduction pathway regulates the production of extracellular virulence factors in C. neoformans, but the influence of the pathway on the secretome has not been investigated. In this study, we performed quantitative proteomics using galactose-inducible and glucose-repressible expression of the PKA1 gene encoding the catalytic subunit of PKA to identify regulated proteins in the secretome. METHODS The proteins in the supernatants of cultures of C. neoformans were precipitated and identified using liquid chromatography-coupled tandem mass spectrometry. We also employed multiple reaction monitoring in a targeted approach to identify fungal proteins in samples from macrophages after phagocytosis of C. neoformans cells, as well as from the blood and bronchoalveolar fluid of infected mice. RESULTS We identified 61 secreted proteins and found that changes in PKA1 expression influenced the extracellular abundance of five proteins, including the Cig1 and Aph1 proteins with known roles in virulence. We also observed a change in the secretome profile upon induction of Pka1 from proteins primarily involved in catabolic and metabolic processes to an expanded set that included proteins for translational regulation and the response to stress. We further characterized the secretome data using enrichment analysis and by predicting conventional versus non-conventional secretion. Targeted proteomics of the Pka1-regulated proteins allowed us to identify the secreted proteins in lysates of phagocytic cells containing C. neoformans, and in samples from infected mice. This analysis also revealed that modulation of PKA1 expression influences the intracellular survival of cryptococcal cells upon phagocytosis. CONCLUSIONS Overall, we found that the cAMP/PKA pathway regulates specific components of the secretome including proteins that affect the virulence of C. neoformans. The detection of secreted cryptococcal proteins from infected phagocytic cells and tissue samples suggests their potential utility as biomarkers of infection. The proteomics data are available via ProteomeXchange with identifiers PXD002731 and PASS00736.
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Affiliation(s)
- Jennifer M H Geddes
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Daniel Croll
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Mélissa Caza
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Nikolay Stoynov
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - Leonard J Foster
- Centre for High-Throughput Biology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
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37
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Affiliation(s)
- Yong-Sun Bahn
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, Republic of Korea
- * E-mail:
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Zhang N, Park YD, Williamson PR. New technology and resources for cryptococcal research. Fungal Genet Biol 2015; 78:99-107. [PMID: 25460849 PMCID: PMC4433448 DOI: 10.1016/j.fgb.2014.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 11/02/2014] [Accepted: 11/06/2014] [Indexed: 11/26/2022]
Abstract
Rapid advances in molecular biology and genome sequencing have enabled the generation of new technology and resources for cryptococcal research. RNAi-mediated specific gene knock down has become routine and more efficient by utilizing modified shRNA plasmids and convergent promoter RNAi constructs. This system was recently applied in a high-throughput screen to identify genes involved in host-pathogen interactions. Gene deletion efficiencies have also been improved by increasing rates of homologous recombination through a number of approaches, including a combination of double-joint PCR with split-marker transformation, the use of dominant selectable markers and the introduction of Cre-Loxp systems into Cryptococcus. Moreover, visualization of cryptococcal proteins has become more facile using fusions with codon-optimized fluorescent tags, such as green or red fluorescent proteins or, mCherry. Using recent genome-wide analytical tools, new transcriptional factors and regulatory proteins have been identified in novel virulence-related signaling pathways by employing microarray analysis, RNA-sequencing and proteomic analysis.
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Affiliation(s)
- Nannan Zhang
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institution of Health, Bethesda, MD, United States
| | - Yoon-Dong Park
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institution of Health, Bethesda, MD, United States
| | - Peter R Williamson
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institution of Health, Bethesda, MD, United States.
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Jung KW, Yang DH, Maeng S, Lee KT, So YS, Hong J, Choi J, Byun HJ, Kim H, Bang S, Song MH, Lee JW, Kim MS, Kim SY, Ji JH, Park G, Kwon H, Cha S, Meyers GL, Wang LL, Jang J, Janbon G, Adedoyin G, Kim T, Averette AK, Heitman J, Cheong E, Lee YH, Lee YW, Bahn YS. Systematic functional profiling of transcription factor networks in Cryptococcus neoformans. Nat Commun 2015; 6:6757. [PMID: 25849373 PMCID: PMC4391232 DOI: 10.1038/ncomms7757] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/24/2015] [Indexed: 02/06/2023] Open
Abstract
Cryptococcus neoformans causes life-threatening meningoencephalitis in humans, but its overall biological and pathogenic regulatory circuits remain elusive, particularly due to the presence of an evolutionarily divergent set of transcription factors (TFs). Here, we report the construction of a high-quality library of 322 signature-tagged gene-deletion strains for 155 putative TF genes previously predicted using the DNA-binding domain TF database, and examine their in vitro and in vivo phenotypic traits under 32 distinct growth conditions. At least one phenotypic trait is exhibited by 145 out of 155 TF mutants (93%) and ∼85% of them (132/155) are functionally characterized for the first time in this study. The genotypic and phenotypic data for each TF are available in the C. neoformans TF phenome database (http://tf.cryptococcus.org). In conclusion, our phenome-based functional analysis of the C. neoformans TF mutant library provides key insights into transcriptional networks of basidiomycetous fungi and human fungal pathogens.
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Affiliation(s)
- Kwang-Woo Jung
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Dong-Hoon Yang
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Shinae Maeng
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Kyung-Tae Lee
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Yee-Seul So
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Joohyeon Hong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Jaeyoung Choi
- Department of Agricultural Biotechnology, Center for Fungal Pathogenesis, Seoul National University, Seoul 151-921, Korea
| | - Hyo-Jeong Byun
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Hyelim Kim
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Soohyun Bang
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Min-Hee Song
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Jang-Won Lee
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Min Su Kim
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Seo-Young Kim
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Je-Hyun Ji
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Goun Park
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Hyojeong Kwon
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Suyeon Cha
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Gena Lee Meyers
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Li Li Wang
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Jooyoung Jang
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Guilhem Janbon
- Unité Biologie et Pathogénicité Fongiques, Département de Mycologie, Institut Pasteur, Paris F-75015, France
| | - Gloria Adedoyin
- Department of Molecular Genetics and Microbiology, Medicine, and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Taeyup Kim
- Department of Molecular Genetics and Microbiology, Medicine, and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Anna K. Averette
- Department of Molecular Genetics and Microbiology, Medicine, and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Medicine, and Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Eunji Cheong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Yong-Hwan Lee
- Department of Agricultural Biotechnology, Center for Fungal Pathogenesis, Seoul National University, Seoul 151-921, Korea
| | - Yin-Won Lee
- Department of Agricultural Biotechnology, Center for Fungal Pathogenesis, Seoul National University, Seoul 151-921, Korea
| | - Yong-Sun Bahn
- Department of Biotechnology, Center for Fungal Pathogenesis, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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40
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Unraveling the biology of a fungal meningitis pathogen using chemical genetics. Cell 2015; 159:1168-1187. [PMID: 25416953 DOI: 10.1016/j.cell.2014.10.044] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/28/2014] [Accepted: 10/22/2014] [Indexed: 01/02/2023]
Abstract
The fungal meningitis pathogen Cryptococcus neoformans is a central driver of mortality in HIV/AIDS. We report a genome-scale chemical genetic data map for this pathogen that quantifies the impact of 439 small-molecule challenges on 1,448 gene knockouts. We identified chemical phenotypes for 83% of mutants screened and at least one genetic response for each compound. C. neoformans chemical-genetic responses are largely distinct from orthologous published profiles of Saccharomyces cerevisiae, demonstrating the importance of pathogen-centered studies. We used the chemical-genetic matrix to predict novel pathogenicity genes, infer compound mode of action, and to develop an algorithm, O2M, that predicts antifungal synergies. These predictions were experimentally validated, thereby identifying virulence genes, a molecule that triggers G2/M arrest and inhibits the Cdc25 phosphatase, and many compounds that synergize with the antifungal drug fluconazole. Our work establishes a chemical-genetic foundation for approaching an infection responsible for greater than one-third of AIDS-related deaths.
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Maier EJ, Haynes BC, Gish SR, Wang ZA, Skowyra ML, Marulli AL, Doering TL, Brent MR. Model-driven mapping of transcriptional networks reveals the circuitry and dynamics of virulence regulation. Genome Res 2015; 25:690-700. [PMID: 25644834 PMCID: PMC4417117 DOI: 10.1101/gr.184101.114] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 01/15/2015] [Indexed: 01/09/2023]
Abstract
Key steps in understanding a biological process include identifying genes that are involved and determining how they are regulated. We developed a novel method for identifying transcription factors (TFs) involved in a specific process and used it to map regulation of the key virulence factor of a deadly fungus—its capsule. The map, built from expression profiles of 41 TF mutants, includes 20 TFs not previously known to regulate virulence attributes. It also reveals a hierarchy comprising executive, midlevel, and “foreman” TFs. When grouped by temporal expression pattern, these TFs explain much of the transcriptional dynamics of capsule induction. Phenotypic analysis of TF deletion mutants revealed complex relationships among virulence factors and virulence in mice. These resources and analyses provide the first integrated, systems-level view of capsule regulation and biosynthesis. Our methods dramatically improve the efficiency with which transcriptional networks can be analyzed, making genomic approaches accessible to laboratories focused on specific physiological processes.
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Affiliation(s)
- Ezekiel J Maier
- Center for Genome Sciences and Systems Biology, Washington University in St. Louis, St. Louis, Missouri 63108, USA; Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Brian C Haynes
- Center for Genome Sciences and Systems Biology, Washington University in St. Louis, St. Louis, Missouri 63108, USA; Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Stacey R Gish
- Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
| | - Zhuo A Wang
- Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
| | - Michael L Skowyra
- Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
| | - Alyssa L Marulli
- Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
| | - Tamara L Doering
- Department of Molecular Microbiology, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
| | - Michael R Brent
- Center for Genome Sciences and Systems Biology, Washington University in St. Louis, St. Louis, Missouri 63108, USA; Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA; Department of Genetics, Washington University in St. Louis School of Medicine, St. Louis, Missouri 63110, USA
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42
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Albuquerque PC, Fonseca FL, Dutra FF, Bozza MT, Frases S, Casadevall A, Rodrigues ML. Cryptococcus neoformans glucuronoxylomannan fractions of different molecular masses are functionally distinct. Future Microbiol 2014; 9:147-61. [PMID: 24571070 DOI: 10.2217/fmb.13.163] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
AIMS Glucuronoxylomannan (GXM) is the major polysaccharide component of Cryptococcus neoformans. We evaluated in this study whether GXM fractions of different molecular masses were functionally distinct. MATERIALS & METHODS GXM samples isolated from C. neoformans cultures were fractionated to generate polysaccharide preparations differing in molecular mass. These fractions were used in experiments focused on the association of GXM with cell wall components of C. neoformans, as well as on the interaction of the polysaccharide with host cells. RESULTS & CONCLUSION GXM fractions of variable molecular masses bound to the surface of a C. neoformans acapsular mutant in a punctate pattern that is in contrast to the usual annular pattern of surface coating observed when GXM samples containing the full molecular mass range were used. The polysaccharide samples were also significantly different in their ability to stimulate cytokine production by host cells. Our findings indicate that GXM fractions are functionally distinct depending on their mass.
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Affiliation(s)
- Priscila C Albuquerque
- Centro de Desenvolvimento Tecnológico em Saúde, CTDS-Fiocruz. Avenida Brasil 4036, Prédio da Expansão, 8o andar, Sala 814, Rio de Janeiro, RJ, 21040-361, Brazil
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43
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Goranov AI, Madhani HD. Functional profiling of human fungal pathogen genomes. Cold Spring Harb Perspect Med 2014; 5:a019596. [PMID: 25377143 DOI: 10.1101/cshperspect.a019596] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Fungal infections are challenging to diagnose and often difficult to treat, with only a handful of drug classes existing. Understanding the molecular mechanisms by which pathogenic fungi cause human disease is imperative. Here, we discuss how the development and use of genome-scale genetic resources, such as whole-genome knockout collections, can address this unmet need. Using work in Saccharomcyes cerevisiae as a guide, studies of Cryptococcus neoformans and Candida albicans have shown how the challenges of large-scale gene deletion can be overcome, and how such collections can be effectively used to obtain insights into mechanisms of pathogenesis. We conclude that, with concerted efforts, full genome-wide functional analysis of human fungal pathogen genomes is within reach.
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Affiliation(s)
- Alexi I Goranov
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94158
| | - Hiten D Madhani
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94158
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44
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Abstract
Few among the millions of fungal species fulfill four basic conditions necessary to infect humans: high temperature tolerance, ability to invade the human host, lysis and absorption of human tissue, and resistance to the human immune system. In previously healthy individuals, invasive fungal disease is rare because animals' sophisticated immune systems evolved in constant response to fungal challenges. In contrast, fungal diseases occur frequently in immunocompromised patients. Paradoxically, successes of modern medicine have put increasing numbers of patients at risk for invasive fungal infections. Uncontrolled HIV infection additionally makes millions vulnerable to lethal fungal diseases. A concerted scientific and social effort is needed to meet these challenges.
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Affiliation(s)
- Julia R Köhler
- Division of Infectious Diseases, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115
| | - Arturo Casadevall
- Departments of Microbiology and Immunology and Medicine, Division of Infectious Diseases, Albert Einstein College of Medicine, New York, New York 10461
| | - John Perfect
- Division of Infectious Diseases, Duke Medical Center, Durham, North Carolina 27710
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45
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Cross talk between the cell wall integrity and cyclic AMP/protein kinase A pathways in Cryptococcus neoformans. mBio 2014; 5:mBio.01573-14. [PMID: 25118241 PMCID: PMC4145688 DOI: 10.1128/mbio.01573-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Cryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis of C. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely, PKC1, BCK1, MKK2, and MPK1 results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions of BCK1, MKK2, and MPK1 compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis. Cryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis of C. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.
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46
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Coelho C, Bocca AL, Casadevall A. The tools for virulence of Cryptococcus neoformans. ADVANCES IN APPLIED MICROBIOLOGY 2014; 87:1-41. [PMID: 24581388 DOI: 10.1016/b978-0-12-800261-2.00001-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cryptococcus neoformans is a fungal pathogen that causes almost half a million deaths each year. It is believed that most humans are infected with C. neoformans, possibly in a form that survives through latency in the lung and can reactivate to cause disease if the host becomes immunosuppressed. C. neoformans has a remarkably sophisticated intracellular survival capacities yet it is a free-living fungus with no requirement for mammalian virulence whatsoever. In this review, we discuss the tools that C. neoformans possesses to achieve survival, latency and virulence within its host. Some of these tools are mechanisms to withstand starvation and others aim to protect against microbicidal molecules produced by the immune system. Furthermore, we discuss how these tools were acquired through evolutionary pressures and perhaps accidental stochastic events, all of which combined to produce an organism with an unusual and unique intracellular pathogenic strategy.
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Affiliation(s)
- Carolina Coelho
- Department of Microbiology and Immunology, Albert Einstein College of Medicine of Yeshiva University, New York, USA; Centre for Neuroscience and Cell Biology of Coimbra, Institute of Microbiology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Anamelia Lorenzetti Bocca
- Department of Cellular Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
| | - Arturo Casadevall
- Department of Microbiology and Immunology, Albert Einstein College of Medicine of Yeshiva University, New York, USA.
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47
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Pbx proteins in Cryptococcus neoformans cell wall remodeling and capsule assembly. EUKARYOTIC CELL 2014; 13:560-71. [PMID: 24585882 DOI: 10.1128/ec.00290-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The cryptococcal capsule is a critical virulence factor of an important pathogen, but little is known about how it is associated with the cell or released into the environment. Two mutants lacking PBX1 and PBX2 were found to shed reduced amounts of the capsule polysaccharide glucuronoxylomannan (GXM). Nuclear magnetic resonance, composition, and physical analyses showed that the shed material was of normal mass but was slightly enriched in xylose. In contrast to previous reports, this material contained no glucose. Notably, the capsule fibers of pbxΔ mutant cells grown under capsule-inducing conditions were present at a lower than usual density and were loosely attached to the cell wall. Mutant cell walls were also defective, as indicated by phenotypes including abnormal cell morphology, reduced mating filamentation, and altered cell integrity. All observed phenotypes were shared between the two mutants and exacerbated in a double mutant. Consistent with a role in surface glycan synthesis, the Pbx proteins localized to detergent-resistant membrane domains. These results, together with the sequence motifs in the Pbx proteins, suggest that Pbx1 and Pbx2 are redundant proteins that act in remodeling the cell wall to maintain normal cell morphology and precursor availability for other glycan synthetic processes. Their absence results in aberrant cell wall growth and metabolic imbalance, which together impact cell wall and capsule synthesis, cell morphology, and capsule association. The surface changes also lead to increased engulfment by host phagocytes, consistent with the lack of virulence of pbx mutants in animal models.
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48
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Guerra CR, Seabra SH, de Souza W, Rozental S. Cryptococcus neoformans is internalized by receptor-mediated or 'triggered' phagocytosis, dependent on actin recruitment. PLoS One 2014; 9:e89250. [PMID: 24586631 PMCID: PMC3931709 DOI: 10.1371/journal.pone.0089250] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 01/17/2014] [Indexed: 12/26/2022] Open
Abstract
Cryptococcosis by the encapsulated yeast Cryptococcus neoformans affects mostly immunocompromised individuals and is a frequent neurological complication in AIDS patients. Recent studies support the idea that intracellular survival of Cryptococcus yeast cells is important for the pathogenesis of cryptococcosis. However, the initial steps of Cryptococcus internalization by host cells remain poorly understood. Here, we investigate the mechanism of Cryptococcus neoformans phagocytosis by peritoneal macrophages using confocal and electron microscopy techniques, as well as flow cytometry quantification, evaluating the importance of fungal capsule production and of host cell cytoskeletal elements for fungal phagocytosis. Electron microscopy analyses revealed that capsular and acapsular strains of C. neoformans are internalized by macrophages via both 'zipper' (receptor-mediated) and 'trigger' (membrane ruffle-dependent) phagocytosis mechanisms. Actin filaments surrounded phagosomes of capsular and acapsular yeasts, and the actin depolymerizing drugs cytochalasin D and latrunculin B inhibited yeast internalization and actin recruitment to the phagosome area. In contrast, nocodazole and paclitaxel, inhibitors of microtubule dynamics decreased internalization but did not prevent actin recruitment to the site of phagocytosis. Our results show that different uptake mechanisms, dependent on both actin and tubulin dynamics occur during yeast internalization by macrophages, and that capsule production does not affect the mode of Cryptococcus uptake by host cells.
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Affiliation(s)
- Caroline Rezende Guerra
- Laboratório de Biologia Celular de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro/RJ, Brazil
| | - Sergio Henrique Seabra
- Laboratório de Tecnologia em Bioquímica e Microscopia, Colegiado de Ciências Biológicas e da Saúde, Centro Universitário Estadual da Zona Oeste, Campo Grande/RJ, Brazil
| | - Wanderley de Souza
- Instituto Nacional de Metrologia Qualidade e Tecnologia, Duque de Caxias/RJ, Brazil
- Instituto Nacional de Biologia Estrutural e Bioimagens, Universidade Federal do Rio de Janeiro, Rio de Janeiro/RJ, Brazil
| | - Sonia Rozental
- Laboratório de Biologia Celular de Fungos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro/RJ, Brazil
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49
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Abstract
Cryptococcus neoformans is the leading cause of fungal meningitis worldwide. Previous studies have characterized the cryptococcal transcriptome under various stress conditions, but a comprehensive profile of the C. neoformans transcriptome in the human host has not been attempted. Here, we extracted RNA from yeast cells taken directly from the cerebrospinal fluid (CSF) of two AIDS patients with cryptococcal meningitis prior to antifungal therapy. The patients were infected with strains of C. neoformans var. grubii of molecular type VNI and VNII. Using RNA-seq, we compared the transcriptional profiles of these strains under three environmental conditions (in vivo CSF, ex vivo CSF, and yeast extract-peptone-dextrose [YPD]). Although we identified a number of differentially expressed genes, single nucleotide variants, and novel genes that were unique to each strain, the overall expression patterns of the two strains were similar under the same environmental conditions. Specifically, yeast cells obtained directly from each patient’s CSF were more metabolically active than cells that were incubated ex vivo in CSF. Compared with growth in YPD, some genes were identified as significantly upregulated in both in vivo and ex vivo CSF, and they were associated with genes previously recognized for contributing to pathogenicity. For example, genes with known stress response functions, such as RIM101, ENA1, and CFO1, were regulated similarly in the two clinical strains. Conversely, many genes that were differentially regulated between the two strains appeared to be transporters. These findings establish a platform for further studies of how this yeast survives and produces disease. Cryptococcus neoformans, an environmental, opportunistic yeast, is annually responsible for an estimated million cases of meningitis and over 600,000 deaths, mostly among HIV-infected patients in sub-Saharan Africa and Asia. Using RNA-seq, we analyzed the gene expression of two strains of C. neoformans obtained from the cerebrospinal fluid (CSF) of infected patients, thus creating a comprehensive snapshot of the yeasts’ genetic responses within the human body. By comparing the gene expression of each clinical strain under three conditions (in vivo CSF, ex vivo CSF, and laboratory culture), we identified genes and pathways that were uniquely regulated by exposure to CSF and likely crucial for the survival of C. neoformans in the central nervous system. Further analyses revealed genetic diversity between the strains, providing evidence for cryptococcal evolution and strain specificity. This ability to characterize transcription in vivo enables the elucidation of specific genetic responses that promote disease production and progression.
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50
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Srikanta D, Santiago-Tirado FH, Doering TL. Cryptococcus neoformans: historical curiosity to modern pathogen. Yeast 2014; 31:47-60. [PMID: 24375706 PMCID: PMC3938112 DOI: 10.1002/yea.2997] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Revised: 12/06/2013] [Accepted: 12/10/2013] [Indexed: 12/22/2022] Open
Abstract
The importance of the Basidiomycete Cryptococcus neoformans to human health has stimulated its development as an experimental model for both basic physiology and pathogenesis. We briefly review the history of this fascinating and versatile fungus, some notable aspects of its biology that contribute to virulence, and current tools available for its study.
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Affiliation(s)
- Deepa. Srikanta
- Department of Molecular Microbiology, Washington University School of Medicine
| | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine
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