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Kramara J, Kim MJ, Ollinger TL, Ristow LC, Wakade RS, Zarnowski R, Wellington M, Andes DR, Mitchell AG, Krysan DJ. Systematic analysis of the Candida albicans kinome reveals environmentally contingent protein kinase-mediated regulation of filamentation and biofilm formation in vitro and in vivo. mBio 2024:e0124924. [PMID: 38949302 DOI: 10.1128/mbio.01249-24] [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: 04/25/2024] [Accepted: 05/20/2024] [Indexed: 07/02/2024] Open
Abstract
Protein kinases are critical regulatory proteins in both prokaryotes and eukaryotes. Accordingly, protein kinases represent a common drug target for a wide range of human diseases. Therefore, understanding protein kinase function in human pathogens such as the fungus Candida albicans is likely to extend our knowledge of its pathobiology and identify new potential therapies. To facilitate the study of C. albicans protein kinases, we constructed a library of 99 non-essential protein kinase homozygous deletion mutants marked with barcodes in the widely used SN genetic background. Here, we describe the construction of this library and the characterization of the competitive fitness of the protein kinase mutants under 11 different growth and stress conditions. We also screened the library for protein kinase mutants with altered filamentation and biofilm formation, two critical virulence traits of C. albicans. An extensive network of protein kinases governs these virulence traits in a manner highly dependent on the specific environmental conditions. Studies on specific protein kinases revealed that (i) the cell wall integrity MAPK pathway plays a condition-dependent role in filament initiation and elongation; (ii) the hyper-osmolar glycerol MAPK pathway is required for both filamentation and biofilm formation, particularly in the setting of in vivo catheter infection; and (iii) Sok1 is dispensable for filamentation in hypoxic environments at the basal level of a biofilm but is required for filamentation in normoxia. In addition to providing a new genetic resource for the community, these observations emphasize the environmentally contingent function of C. albicans protein kinases.IMPORTANCECandida albicans is one of the most common causes of fungal disease in humans for which new therapies are needed. Protein kinases are key regulatory proteins and are increasingly targeted by drugs for the treatment of a wide range of diseases. Understanding protein kinase function in C. albicans pathogenesis may facilitate the development of new antifungal drugs. Here, we describe a new library of 99 protein kinase deletion mutants to facilitate the study of protein kinases. Furthermore, we show that the function of protein kinases in two virulence-related processes, filamentation and biofilm formation, is dependent on the specific environmental conditions.
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Affiliation(s)
- Juraj Kramara
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Min-Ju Kim
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Tomye L Ollinger
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Laura C Ristow
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Rohan S Wakade
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Robert Zarnowski
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, USA
| | - Melanie Wellington
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - David R Andes
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, USA
| | - Aaron G Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Damian J Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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2
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Queiroz da Silva ML, Ferreira de Sousa N, Dos Santos ATL, de Sousa GR, Fonseca VJA, Douglas Melo Coutinho H, Barbosa Filho JM, de Souza Ferrari J, Scotti MT, Ribeiro-Filho J, Martins de Lima JP, da Rocha JBT, Bezerra Morais-Braga MF. Inhibition of the morphological transition of Candida spp. by riparins I-IV. Fundam Clin Pharmacol 2024:e13007. [PMID: 38738393 DOI: 10.1111/fcp.13007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 03/19/2024] [Accepted: 04/19/2024] [Indexed: 05/14/2024]
Abstract
Candida spp. is an opportunistic pathogen capable of causing superficial to invasive infections. Morphological transition is one of the main virulence factors of this genus and, therefore, is an important variable to be considered in pharmacological interventions. Riparins I, II, III, and IV are alkamide-type alkaloids extracted from the unripe fruit of Aniba riparia, whose remarkable pharmacological properties were previously demonstrated. This work aimed to evaluate in silico and in vitro the inhibitory effects of Riparins on the morphological transition of Candida albicans, Candida tropicalis, and Candida krusei. Molecular docking was applied to analyze the inhibitory effects of riparins against proteins such as N-acetylglucosamine, CYP-51, and protein kinase A (PKA) using the Ramachandran plot. The ligands were prepared by MarvinSketch and Spartan software version 14.0, and MolDock Score and Rerank Score were used to analyze the affinity of the compounds. In vitro analyses were performed by culturing the strains in humid chambers in the presence of riparins or fluconazole (FCZ). The morphology was observed through optical microscopy, and the size of the hyphae was determined using the ToupView software. In silico analysis demonstrated that all riparins are likely to interact with the molecular targets: GlcNAc (>50%), PKA (>60%), and CYP-51 (>70%). Accordingly, in vitro analysis showed that these compounds significantly inhibited the morphological transition of all Candida strains. In conclusion, this study demonstrated that riparins inhibit Candida morphological transition and, therefore, can be used to overcome the pathogenicity of this genus.
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Affiliation(s)
| | - Natália Ferreira de Sousa
- Laboratório de Quimioinformática, Departamento de Química, Universidade Federal da Paraíba (UFPB), São João do Cariri, Brazil
| | | | - Gabriela Ribeiro de Sousa
- Departamento de Ciências da Saúde, Universidade Federal da Paraiba (UFPB), São João do Cariri, Brazil
| | | | | | - José Maria Barbosa Filho
- Departamento de Ciências da Saúde, Universidade Federal da Paraiba (UFPB), São João do Cariri, Brazil
| | | | - Marcus Tullius Scotti
- Laboratório de Quimioinformática, Departamento de Química, Universidade Federal da Paraíba (UFPB), São João do Cariri, Brazil
| | | | | | - João Batista Teixeira da Rocha
- Departamento de Química Biológica, Universidade Regional do Cariri (URCA), Crato, Brazil
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Santa Maria (UFSM), Santa Maria, Brazil
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3
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Bing J, Guan Z, Zheng T, Ennis CL, Nobile CJ, Chen C, Chu H, Huang G. Rapid evolution of an adaptive multicellular morphology of Candida auris during systemic infection. Nat Commun 2024; 15:2381. [PMID: 38493178 PMCID: PMC10944540 DOI: 10.1038/s41467-024-46786-8] [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: 10/30/2023] [Accepted: 03/08/2024] [Indexed: 03/18/2024] Open
Abstract
Candida auris has become a serious threat to public health. The mechanisms of how this fungal pathogen adapts to the mammalian host are poorly understood. Here we report the rapid evolution of an adaptive C. auris multicellular aggregative morphology in the murine host during systemic infection. C. auris aggregative cells accumulate in the brain and exhibit obvious advantages over the single-celled yeast-form cells during systemic infection. Genetic mutations, specifically de novo point mutations in genes associated with cell division or budding processes, underlie the rapid evolution of this aggregative phenotype. Most mutated C. auris genes are associated with the regulation of cell wall integrity, cytokinesis, cytoskeletal properties, and cellular polarization. Moreover, the multicellular aggregates are notably more recalcitrant to the host antimicrobial peptides LL-37 and PACAP relative to the single-celled yeast-form cells. Overall, to survive in the host, C. auris can rapidly evolve a multicellular aggregative morphology via genetic mutations.
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Affiliation(s)
- Jian Bing
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Shanghai Engineering Research Center of Industrial Microorganisms, Shanghai, 200438, China
| | - Zhangyue Guan
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Tianhong Zheng
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Craig L Ennis
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95343, USA
- Quantitative and Systems Biology Graduate Program, University of California, Merced, Merced, CA, 95343, USA
| | - Clarissa J Nobile
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA, 95343, USA
- Health Sciences Research Institute, University of California, Merced, Merced, CA, 95343, USA
| | - Changbin Chen
- The Center for Microbes, Development, and Health, Key Laboratory of Molecular Virology and Immunology, Unit of Pathogenic Fungal Infection & Host Immunity, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Haiqing Chu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China.
- Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China.
| | - Guanghua Huang
- Shanghai Institute of Infectious Disease and Biosecurity, Department of infectious diseases, Huashan Hospital and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.
- College of Pharmaceutical Sciences, Southwest University, Chongqing, 400716, China.
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MacAlpine J, Liu Z, Hossain S, Whitesell L, Robbins N, Cowen LE. DYRK-family kinases regulate Candida albicans morphogenesis and virulence through the Ras1/PKA pathway. mBio 2023; 14:e0218323. [PMID: 38015416 PMCID: PMC10746247 DOI: 10.1128/mbio.02183-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 10/12/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Candida albicans is an opportunistic human fungal pathogen that frequently causes life-threatening infections in immunocompromised individuals. To cause disease, the fungus employs several virulence traits, including its ability to transition between yeast and filamentous states. Previous work identified a role for the kinase Yak1 in regulating C. albicans filamentation. Here, we demonstrate that Yak1 regulates morphogenesis through the canonical cAMP/PKA pathway and that this regulation is environmentally contingent, as host-relevant concentrations of CO2 bypass the requirement of Yak1 for C. albicans morphogenesis. We show a related kinase, Pom1, is important for filamentation in the absence of Yak1 under these host-relevant conditions, as deletion of both genes blocked filamentous growth under all conditions tested. Finally, we demonstrate that Yak1 is required for filamentation in a mouse model of C. albicans dermatitis using genetic and pharmacological approaches. Overall, our results expand our understanding of how Yak1 regulates an important virulence trait in C. albicans.
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Affiliation(s)
- Jessie MacAlpine
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Zhongle Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Saif Hossain
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Luke Whitesell
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - 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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5
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Lohse MB, Ziv N, Johnson AD. Variation in transcription regulator expression underlies differences in white-opaque switching between the SC5314 reference strain and the majority of Candida albicans clinical isolates. Genetics 2023; 225:iyad162. [PMID: 37811798 PMCID: PMC10627253 DOI: 10.1093/genetics/iyad162] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 08/26/2023] [Indexed: 10/10/2023] Open
Abstract
Candida albicans, a normal member of the human microbiome and an opportunistic fungal pathogen, undergoes several morphological transitions. One of these transitions is white-opaque switching, where C. albicans alternates between 2 stable cell types with distinct cellular and colony morphologies, metabolic preferences, mating abilities, and interactions with the innate immune system. White-to-opaque switching is regulated by mating type; it is repressed by the a1/α2 heterodimer in a/α cells, but this repression is lifted in a/a and α/α mating type cells (each of which are missing half of the repressor). The widely used C. albicans reference strain, SC5314, is unusual in that white-opaque switching is completely blocked when the cells are a/α; in contrast, most other C. albicans a/α strains can undergo white-opaque switching at an observable level. In this paper, we uncover the reason for this difference. We show that, in addition to repression by the a1/α2 heterodimer, SC5314 contains a second block to white-opaque switching: 4 transcription regulators of filamentous growth are upregulated in this strain and collectively suppress white-opaque switching. This second block is missing in the majority of clinical strains, and, although they still contain the a1/α2 heterodimer repressor, they exhibit a/α white-opaque switching at an observable level. When both blocks are absent, white-opaque switching occurs at very high levels. This work shows that white-opaque switching remains intact across a broad group of clinical strains, but the precise way it is regulated and therefore the frequency at which it occurs varies from strain to strain.
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Affiliation(s)
- Matthew B Lohse
- Department of Microbiology and Immunology, University of California - San Francisco, San Francisco, CA 94143, USA
| | - Naomi Ziv
- Department of Microbiology and Immunology, University of California - San Francisco, San Francisco, CA 94143, USA
| | - Alexander D Johnson
- Department of Microbiology and Immunology, University of California - San Francisco, San Francisco, CA 94143, USA
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6
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Zhang K, Sun IG, Liao B, Yang Y, Ma H, Jiang A, Chen S, Guo Q, Ren B. Streptococcus mutans sigX-inducing peptide inhibits the virulence of Candida albicans and oral candidiasis through the Ras1-cAMP-Efg1 pathway. Int J Antimicrob Agents 2023; 62:106855. [PMID: 37211262 DOI: 10.1016/j.ijantimicag.2023.106855] [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: 03/29/2023] [Revised: 05/04/2023] [Accepted: 05/12/2023] [Indexed: 05/23/2023]
Abstract
Oral candidiasis is the most common fungal infectious disease in the human oral cavity, and Candida albicans is the major pathogenic agent. Increasing drug resistance and the lack of new types of antifungals greatly increase the challenges for treating fungal infections. Targeting hyphal transition provides a promising strategy to inhibit the virulence of C. albicans and overcome drug resistance. This study aimed to investigate the effects and mechanisms of sigX-inducing peptide (XIP), a quorum-sensing signal peptide secreted by Streptococcus mutans, on C. albicans hyphal development and biofilm formation in vitro and oropharyngeal candidiasis in vivo. XIP significantly inhibited C. albicans yeast-to-hypha transition and biofilm formation in a dose-dependent manner from 0.01 to 0.1 µM. XIP significantly downregulated expression of genes from the Ras1-cAMP-Efg1 pathway (RAS1, CYR1, TPK2, EFG1 and UME6), a key pathway to regulate C. albicans hyphal development. Importantly, XIP reduced the levels of key molecules cAMP and ATP from this pathway, while the addition of exogenous cAMP and overexpression of RAS1 restored the hyphal development inhibited by XIP. XIP also lost its hyphal inhibitory effects on ras1Δ/Δ and efg1Δ/Δ strains. These results further confirmed that XIP inhibited hyphal development through downregulation of the Ras1-cAMP-Efg1 pathway. A murine oropharyngeal candidiasis model was employed to evaluate the therapeutic effects of XIP on oral candidiasis. XIP effectively reduced the infected epithelial area, fungal burden, hyphal invasion and inflammatory infiltrates. These results revealed the antifungal effects of XIP, and highlighted that XIP can be a potential antifungal peptide against C. albicans infection.
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Affiliation(s)
- Kaiwen Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Orthodontics Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ivy Guofang Sun
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Faculty of Dentistry, The University of Hong Kong, Hong Kong, China
| | - Binyou Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yichun Yang
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Huangshui Ma
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Aiming Jiang
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Song Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Orthodontics Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qiang Guo
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| | - Biao Ren
- State Key Laboratory of Oral Diseases, National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
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7
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Larcombe DE, Bohovych IM, Pradhan A, Ma Q, Hickey E, Leaves I, Cameron G, Avelar GM, de Assis LJ, Childers DS, Bain JM, Lagree K, Mitchell AP, Netea MG, Erwig LP, Gow NAR, Brown AJP. Glucose-enhanced oxidative stress resistance-A protective anticipatory response that enhances the fitness of Candida albicans during systemic infection. PLoS Pathog 2023; 19:e1011505. [PMID: 37428810 PMCID: PMC10358912 DOI: 10.1371/journal.ppat.1011505] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 07/20/2023] [Accepted: 06/22/2023] [Indexed: 07/12/2023] Open
Abstract
Most microbes have developed responses that protect them against stresses relevant to their niches. Some that inhabit reasonably predictable environments have evolved anticipatory responses that protect against impending stresses that are likely to be encountered in their niches-termed "adaptive prediction". Unlike yeasts such as Saccharomyces cerevisiae, Kluyveromyces lactis and Yarrowia lipolytica and other pathogenic Candida species we examined, the major fungal pathogen of humans, Candida albicans, activates an oxidative stress response following exposure to physiological glucose levels before an oxidative stress is even encountered. Why? Using competition assays with isogenic barcoded strains, we show that "glucose-enhanced oxidative stress resistance" phenotype enhances the fitness of C. albicans during neutrophil attack and during systemic infection in mice. This anticipatory response is dependent on glucose signalling rather than glucose metabolism. Our analysis of C. albicans signalling mutants reveals that the phenotype is not dependent on the sugar receptor repressor pathway, but is modulated by the glucose repression pathway and down-regulated by the cyclic AMP-protein kinase A pathway. Changes in catalase or glutathione levels do not correlate with the phenotype, but resistance to hydrogen peroxide is dependent on glucose-enhanced trehalose accumulation. The data suggest that the evolution of this anticipatory response has involved the recruitment of conserved signalling pathways and downstream cellular responses, and that this phenotype protects C. albicans from innate immune killing, thereby promoting the fitness of C. albicans in host niches.
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Affiliation(s)
- Daniel E. Larcombe
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Iryna M. Bohovych
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Arnab Pradhan
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Qinxi Ma
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Emer Hickey
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Ian Leaves
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Gary Cameron
- Rowett Institute, School of Medicine Medical Sciences & Nutrition, University of Aberdeen, Aberdeen, United Kingdom
| | - Gabriela M. Avelar
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Leandro J. de Assis
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Delma S. Childers
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Judith M. Bain
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Katherine Lagree
- Department of Microbiology, Biosciences Building, University of Georgia, Athens, Georgia, United States of America
| | - Aaron P. Mitchell
- Department of Microbiology, Biosciences Building, University of Georgia, Athens, Georgia, United States of America
| | - Mihai G. Netea
- Department of Internal Medicine and Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
- Department for Immunology & Metabolism, Life and Medical Sciences Institute, University of Bonn, Bonn, Germany
| | - Lars P. Erwig
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Johnson-Johnson Innovation, EMEA Innovation Centre, One Chapel Place, London, United Kingdom
| | - Neil A. R. Gow
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
| | - Alistair J. P. Brown
- Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Medical Research Council Centre for Medical Mycology, University of Exeter, School of Biosciences, Geoffrey Pope Building, Exeter, United Kingdom
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8
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Assa D, Voorhies M, Sil A. Chemical stimuli override a temperature-dependent morphological program by reprogramming the transcriptome of a fungal pathogen. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.21.537729. [PMID: 37131633 PMCID: PMC10153268 DOI: 10.1101/2023.04.21.537729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The human fungal pathogen Histoplasma changes its morphology in response to temperature. At 37°C it grows as a budding yeast whereas at room temperature it transitions to hyphal growth. Prior work has demonstrated that 15-20% of transcripts are temperature-regulated, and that transcription factors Ryp1-4 are necessary to establish yeast growth. However, little is known about transcriptional regulators of the hyphal program. To identify TFs that regulate filamentation, we utilize chemical inducers of hyphal growth. We show that addition of cAMP analogs or an inhibitor of cAMP breakdown overrides yeast morphology, yielding inappropriate hyphal growth at 37°C. Additionally, butyrate supplementation triggers hyphal growth at 37°C. Transcriptional profiling of cultures filamenting in response to cAMP or butyrate reveals that a limited set of genes respond to cAMP while butyrate dysregulates a larger set. Comparison of these profiles to previous temperature- or morphology-regulated gene sets identifies a small set of morphology-specific transcripts. This set contains 9 TFs of which we characterized three, STU1 , FBC1 , and PAC2 , whose orthologs regulate development in other fungi. We found that each of these TFs is individually dispensable for room-temperature (RT) induced filamentation but each is required for other aspects of RT development. FBC1 and PAC2 , but not STU1 , are necessary for filamentation in response to cAMP at 37°C. Ectopic expression of each of these TFs is sufficient to induce filamentation at 37°C. Finally, PAC2 induction of filamentation at 37°C is dependent on STU1 , suggesting these TFs form a regulatory circuit that, when activated at RT, promotes the hyphal program. Importance Fungal illnesses pose a significant disease burden. However, the regulatory circuits that govern the development and virulence of fungi remain largely unknown. This study utilizes chemicals that can override the normal growth morphology of the human pathogen Histoplasma . Using transcriptomic approaches, we identify novel regulators of hyphal morphology and refine our understanding of the transcriptional circuits governing morphology in Histoplasma .
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9
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Wakade RS, Ristow LC, Wellington M, Krysan DJ. Intravital imaging-based genetic screen reveals the transcriptional network governing Candida albicans filamentation during mammalian infection. eLife 2023; 12:e85114. [PMID: 36847358 PMCID: PMC9995110 DOI: 10.7554/elife.85114] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 02/26/2023] [Indexed: 03/01/2023] Open
Abstract
Candida albicans is one of the most common human fungal pathogens. C. albicans pathogenesis is tightly linked to its ability to under a morphogenetic transition from typically budding yeast to filamentous forms of hyphae and pseudohyphae. Filamentous morphogenesis is the most intensively studied C. albicans virulence traits; however, nearly all of these studies have been based on in vitro induction of filamentation. Using an intravital imaging assay of filamentation during mammalian (mouse) infection, we have screened a library of transcription factor mutants to identify those that modulate both the initiation and maintenance of filamentation in vivo. We coupled this initial screen with genetic interaction analysis and in vivo transcription profiling to characterize the transcription factor network governing filamentation in infected mammalian tissue. Three core positive (Efg1, Brg1, and Rob1) and two core negative regulators (Nrg1 and Tup1) of filament initiation were identified. No previous systematic analysis of genes affecting the elongation step has been reported and we found that large set of transcription factors affect filament elongation in vivo including four (Hms1, Lys14, War1, Dal81) with no effect on in vitro elongation. We also show that the gene targets of initiation and elongation regulators are distinct. Genetic interaction analysis of the core positive and negative regulators revealed that the master regulator Efg1 primarily functions to mediate relief of Nrg1 repression and is dispensable for expression of hypha-associated genes in vitro and in vivo. Thus, our analysis not only provide the first characterization of the transcriptional network governing C. albicans filamentation in vivo but also revealed a fundamentally new mode of function for Efg1, one of the most widely studied C. albicans transcription factors.
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Affiliation(s)
- Rohan S Wakade
- Department of Pediatrics, Carver College of Medicine, University of IowaIowa CityUnited States
| | - Laura C Ristow
- Department of Pediatrics, Carver College of Medicine, University of IowaIowa CityUnited States
| | - Melanie Wellington
- Department of Pediatrics, Carver College of Medicine, University of IowaIowa CityUnited States
| | - Damian J Krysan
- Department of Pediatrics, Carver College of Medicine, University of IowaIowa CityUnited States
- Departments of Microbiology and Immunology, Carver College of Medicine, University of IowaIowa CityUnited States
- Molecular Physiology and Biophysics, Carver College of Medicine, University of IowaIowa CityUnited States
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10
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Brown AJP. Fungal resilience and host-pathogen interactions: Future perspectives and opportunities. Parasite Immunol 2023; 45:e12946. [PMID: 35962618 PMCID: PMC10078341 DOI: 10.1111/pim.12946] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 01/31/2023]
Abstract
We are constantly exposed to the threat of fungal infection. The outcome-clearance, commensalism or infection-depends largely on the ability of our innate immune defences to clear infecting fungal cells versus the success of the fungus in mounting compensatory adaptive responses. As each seeks to gain advantage during these skirmishes, the interactions between host and fungal pathogen are complex and dynamic. Nevertheless, simply compromising the physiological robustness of fungal pathogens reduces their ability to evade antifungal immunity, their virulence, and their tolerance against antifungal therapy. In this article I argue that this physiological robustness is based on a 'Resilience Network' which mechanistically links and controls fungal growth, metabolism, stress resistance and drug tolerance. The elasticity of this network probably underlies the phenotypic variability of fungal isolates and the heterogeneity of individual cells within clonal populations. Consequently, I suggest that the definition of the fungal Resilience Network represents an important goal for the future which offers the clear potential to reveal drug targets that compromise drug tolerance and synergise with current antifungal therapies.
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Affiliation(s)
- Alistair J P Brown
- Medical Research Council Centre for Medical Mycology at the University of Exeter, Exeter, UK
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11
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Brenes LR, Johnson AD, Lohse MB. Farnesol and phosphorylation of the transcriptional regulator Efg1 affect Candida albicans white-opaque switching rates. PLoS One 2023; 18:e0280233. [PMID: 36662710 PMCID: PMC9858334 DOI: 10.1371/journal.pone.0280233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 12/24/2022] [Indexed: 01/21/2023] Open
Abstract
Candida albicans is a normal member of the human microbiome and an opportunistic fungal pathogen. This species undergoes several morphological transitions, and here we consider white-opaque switching. In this switching program, C. albicans reversibly alternates between two cell types, named "white" and "opaque," each of which is normally stable across thousands of cell divisions. Although switching under most conditions is stochastic and rare, certain environmental signals or genetic manipulations can dramatically increase the rate of switching. Here, we report the identification of two new inputs which affect white-to-opaque switching rates. The first, exposure to sub-micromolar concentrations of (E,E)-farnesol, reduces white-to-opaque switching by ten-fold or more. The second input, an inferred PKA phosphorylation of residue T208 on the transcriptional regulator Efg1, increases white-to-opaque switching ten-fold. Combining these and other environmental inputs results in a variety of different switching rates, indicating that a given rate represents the integration of multiple inputs.
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Affiliation(s)
- Lucas R. Brenes
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, United States of America
| | - Alexander D. Johnson
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, United States of America
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Matthew B. Lohse
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, California, United States of America
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12
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de Assis LJ, Bain JM, Liddle C, Leaves I, Hacker C, Peres da Silva R, Yuecel R, Bebes A, Stead D, Childers DS, Pradhan A, Mackenzie K, Lagree K, Larcombe DE, Ma Q, Avelar GM, Netea MG, Erwig LP, Mitchell AP, Brown GD, Gow NAR, Brown AJP. Nature of β-1,3-Glucan-Exposing Features on Candida albicans Cell Wall and Their Modulation. mBio 2022; 13:e0260522. [PMID: 36218369 PMCID: PMC9765427 DOI: 10.1128/mbio.02605-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 01/15/2023] Open
Abstract
Candida albicans exists as a commensal of mucosal surfaces and the gastrointestinal tract without causing pathology. However, this fungus is also a common cause of mucosal and systemic infections when antifungal immune defenses become compromised. The activation of antifungal host defenses depends on the recognition of fungal pathogen-associated molecular patterns (PAMPs), such as β-1,3-glucan. In C. albicans, most β-1,3-glucan is present in the inner cell wall, concealed by the outer mannan layer, but some β-1,3-glucan becomes exposed at the cell surface. In response to host signals, such as lactate, C. albicans induces the Xog1 exoglucanase, which shaves exposed β-1,3-glucan from the cell surface, thereby reducing phagocytic recognition. We show here that β-1,3-glucan is exposed at bud scars and punctate foci on the lateral wall of yeast cells, that this exposed β-1,3-glucan is targeted during phagocytic attack, and that lactate-induced masking reduces β-1,3-glucan exposure at bud scars and at punctate foci. β-1,3-Glucan masking depends upon protein kinase A (PKA) signaling. We reveal that inactivating PKA, or its conserved downstream effectors, Sin3 and Mig1/Mig2, affects the amounts of the Xog1 and Eng1 glucanases in the C. albicans secretome and modulates β-1,3-glucan exposure. Furthermore, perturbing PKA, Sin3, or Mig1/Mig2 attenuates the virulence of lactate-exposed C. albicans cells in Galleria. Taken together, the data are consistent with the idea that β-1,3-glucan masking contributes to Candida pathogenicity. IMPORTANCE Microbes that coexist with humans have evolved ways of avoiding or evading our immunological defenses. These include the masking by these microbes of their "pathogen-associated molecular patterns" (PAMPs), which are recognized as "foreign" and used to activate protective immunity. The commensal fungus Candida albicans masks the proinflammatory PAMP β-1,3-glucan, which is an essential component of its cell wall. Most of this β-1,3-glucan is hidden beneath an outer layer of the cell wall on these microbes, but some can become exposed at the fungal cell surface. Using high-resolution confocal microscopy, we examine the nature of the exposed β-1,3-glucan at C. albicans bud scars and at punctate foci on the lateral cell wall, and we show that these features are targeted by innate immune cells. We also reveal that downstream effectors of protein kinase A (Mig1/Mig2, Sin3) regulate the secretion of major glucanases, modulate the levels of β-1,3-glucan exposure, and influence the virulence of C. albicans in an invertebrate model of systemic infection. Our data support the view that β-1,3-glucan masking contributes to immune evasion and the virulence of a major fungal pathogen of humans.
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Affiliation(s)
- Leandro José de Assis
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Judith M. Bain
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Corin Liddle
- Bioimaging Unit, University of Exeter, Exeter, United Kingdom
| | - Ian Leaves
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | | | - Roberta Peres da Silva
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Raif Yuecel
- Exeter Centre for Cytomics, University of Exeter, Exeter, United Kingdom
| | - Attila Bebes
- Exeter Centre for Cytomics, University of Exeter, Exeter, United Kingdom
| | - David Stead
- Aberdeen Proteomics Facility, Rowett Institute, University of Aberdeen, Aberdeen, United Kingdom
| | - Delma S. Childers
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Arnab Pradhan
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Kevin Mackenzie
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Katherine Lagree
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Daniel E. Larcombe
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Qinxi Ma
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Gabriela Mol Avelar
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Mihai G. Netea
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
- Radboud Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
- Department for Immunology & Metabolism, Life and Medical Sciences Institute (LIMES), University of Bonn, Bonn, Germany
| | - Lars P. Erwig
- Aberdeen Fungal Group, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
- Johnson-Johnson Innovation, EMEA Innovation Centre, London, United Kingdom
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Gordon D. Brown
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Neil A. R. Gow
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
| | - Alistair J. P. Brown
- Medical Research Council Centre for Medical Mycology, University of Exeter, Exeter, United Kingdom
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13
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Gong C, Xu D, Sun D, Kang J, Wang W, Xu JR, Zhang X. FgSnt1 of the Set3 HDAC complex plays a key role in mediating the regulation of histone acetylation by the cAMP-PKA pathway in Fusarium graminearum. PLoS Genet 2022; 18:e1010510. [PMID: 36477146 PMCID: PMC9728937 DOI: 10.1371/journal.pgen.1010510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 11/01/2022] [Indexed: 12/13/2022] Open
Abstract
The cAMP-PKA pathway is critical for regulating growth, differentiation, and pathogenesis in fungal pathogens. In Fusarium graminearum, mutants deleted of PKR regulatory-subunit of PKA had severe defects but often produced spontaneous suppressors. In this study eleven pkr suppressors were found to have mutations in FgSNT1, a component of the Set3C histone deacetylase (HDAC) complex, that result in the truncation of its C-terminal region. Targeted deletion of the C-terminal 98 aa (CT98) in FgSNT1 suppressed the defects of pkr in growth and H4 acetylation. CT98 truncation also increased the interaction of FgSnt1 with Hdf1, a major HDAC in the Set3 complex. The pkr mutant had no detectable expression of the Cpk1 catalytic subunit and PKA activities, which was not suppressed by mutations in FgSNT1. Cpk1 directly interacted with the N-terminal region of FgSnt1 and phosphorylated it at S443, a conserved PKA-phosphorylation site. CT98 of FgSnt1 carrying the S443D mutation interacted with its own N-terminal region. Expression of FgSNT1S443D rescued the defects of pkr in growth and H4 acetylation. Therefore, phosphorylation at S443 and suppressor mutations may relieve self-inhibitory binding of FgSnt1 and increase its interaction with Hdf1 and H4 acetylation, indicating a key role of FgSnt1 in crosstalk between cAMP signaling and Set3 complex.
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Affiliation(s)
- Chen Gong
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Daiying Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Daiyuan Sun
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Jiangang Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Wei Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail: (J-RX); (XZ)
| | - Xue Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China
- * E-mail: (J-RX); (XZ)
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14
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Candida albicans Filamentation Does Not Require the cAMP-PKA Pathway In Vivo. mBio 2022; 13:e0085122. [PMID: 35475642 PMCID: PMC9239198 DOI: 10.1128/mbio.00851-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Candida albicans is one of the most prevalent human fungal pathogens. Its ability to transition between budding yeast and filamentous morphological forms (pseudohyphae and hyphae) is tightly associated with its pathogenesis. Based on in vitro studies, the cAMP-protein kinase A (PKA) pathway is a key regulator of C. albicans morphogenesis. Using an intravital imaging approach, we investigated the role of the cAMP-PKA pathway during infection. Consistent with their roles in vitro, the downstream effectors of the cAMP-PKA pathway Efg1 and Nrg1 function, respectively, as an activator and a repressor of in vivo filamentation. Surprisingly, strains lacking the adenylyl cyclase, CYR1, showed only slightly reduced filamentation in vivo despite being completely unable to filament in RPMI + 10% serum at 37°C. Consistent with these findings, deletion of the catalytic subunits of PKA (Tpk1 and Tpk2), either singly or in combination, generated strains that also filamented in vivo but not in vitro. In vivo transcription profiling of C. albicans isolated from both ear and kidney tissue showed that the expression of a set of 184 environmentally responsive genes correlated well with in vitro filamentation (R2, 0.62 to 0.68) genes. This concordance suggests that the in vivo and in vitro transcriptional responses are similar but that the upstream regulatory mechanisms are distinct. As such, these data emphatically emphasize that C. albicans filamentation is a complex phenotype that occurs in different environments through an intricate network of distinct regulatory mechanisms. IMPORTANCE The fungus Candida albicans causes a wide range of disease in humans from common diaper rash to life-threatening infections in patients with compromised immune systems. As such, the mechanisms for its ability to cause disease are of wide interest. An intensely studied virulence property of C. albicans is its ability to switch from a round yeast form to filament-like forms (hyphae and pseudohyphae). Surprisingly, we have found that a key signaling pathway that regulates this transition in vitro, the protein kinase A pathway, is not required for filamentation during infection of the host. Our work not only demonstrates that the regulation of filamentation depends upon the specific environment C. albicans inhabits but also underscores the importance of studying these mechanisms during infection.
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15
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Shwab EK, Juvvadi PR, Shaheen SK, Allen J, Waitt G, Soderblom EJ, Asfaw YG, Moseley MA, Steinbach WJ. Protein Kinase A Regulates Autophagy-Associated Proteins Impacting Growth and Virulence of Aspergillus fumigatus. J Fungi (Basel) 2022; 8:jof8040354. [PMID: 35448585 PMCID: PMC9029100 DOI: 10.3390/jof8040354] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/14/2022] [Accepted: 03/28/2022] [Indexed: 01/07/2023] Open
Abstract
Cellular recycling via autophagy-associated proteins is a key catabolic pathway critical to invasive fungal pathogen growth and virulence in the nutrient-limited host environment. Protein kinase A (PKA) is vital for the growth and virulence of numerous fungal pathogens. However, the underlying basis for its regulation of pathogenesis remains poorly understood in any species. Our Aspergillus fumigatus PKA-dependent whole proteome and phosphoproteome studies employing advanced mass spectroscopic approaches identified numerous previously undefined PKA-regulated proteins in catabolic pathways. Here, we demonstrate reciprocal inhibition of autophagy and PKA activity, and identify 16 autophagy-associated proteins as likely novel PKA-regulated effectors. We characterize the novel PKA-phosphoregulated sorting nexin Atg20, and demonstrate its importance for growth, cell wall stress response, and virulence of A. fumigatus in a murine infection model. Additionally, we identify physical and functional interaction of Atg20 with previously characterized sorting nexin Atg24. Furthermore, we demonstrate the importance of additional uncharacterized PKA-regulated putative autophagy-associated proteins to hyphal growth. Our data presented here indicate that PKA regulates the autophagy pathway much more extensively than previously known, including targeting of novel effector proteins with fungal-specific functions important for invasive disease.
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Affiliation(s)
- E. Keats Shwab
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA; (E.K.S.); (P.R.J.); (S.K.S.); (J.A.IV)
| | - Praveen R. Juvvadi
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA; (E.K.S.); (P.R.J.); (S.K.S.); (J.A.IV)
| | - Shareef K. Shaheen
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA; (E.K.S.); (P.R.J.); (S.K.S.); (J.A.IV)
| | - John Allen
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA; (E.K.S.); (P.R.J.); (S.K.S.); (J.A.IV)
| | - Greg Waitt
- Duke Proteomics Core Facility, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27701, USA; (G.W.); (E.J.S.); (M.A.M.)
| | - Erik J. Soderblom
- Duke Proteomics Core Facility, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27701, USA; (G.W.); (E.J.S.); (M.A.M.)
| | - Yohannes G. Asfaw
- Department of Laboratory Animal Resources, Duke University Medical Center, Durham, NC 27710, USA;
| | - M. Arthur Moseley
- Duke Proteomics Core Facility, Institute for Genome Sciences and Policy, Duke University, Durham, NC 27701, USA; (G.W.); (E.J.S.); (M.A.M.)
| | - William J. Steinbach
- Department of Pediatrics, Division of Pediatric Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA; (E.K.S.); (P.R.J.); (S.K.S.); (J.A.IV)
- Department of Molecular Genetics & Microbiology, Duke University Medical Center, Durham, NC 27710, USA
- Correspondence:
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16
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Glazier VE. EFG1, Everyone’s Favorite Gene in Candida albicans: A Comprehensive Literature Review. Front Cell Infect Microbiol 2022; 12:855229. [PMID: 35392604 PMCID: PMC8980467 DOI: 10.3389/fcimb.2022.855229] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 02/24/2022] [Indexed: 12/18/2022] Open
Abstract
Candida sp. are among the most common fungal commensals found in the human microbiome. Although Candida can be found residing harmlessly on the surface of the skin and mucosal membranes, these opportunistic fungi have the potential to cause superficial skin, nail, and mucus membrane infections as well as life threatening systemic infections. Severity of infection is dependent on both fungal and host factors including the immune status of the host. Virulence factors associated with Candida sp. pathogenicity include adhesin proteins, degradative enzymes, phenotypic switching, and morphogenesis. A central transcriptional regulator of morphogenesis, the transcription factor Efg1 was first characterized in Candida albicans in 1997. Since then, EFG1 has been referenced in the Candida literature over three thousand times, with the number of citations growing daily. Arguably one of the most well studied genes in Candida albicans, EFG1 has been referenced in nearly all contexts of Candida biology from the development of novel therapeutics to white opaque switching, hyphae morphology to immunology. In the review that follows we will synthesize the research that has been performed on this extensively studied transcription factor and highlight several important unanswered questions.
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17
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Das S, Goswami AM, Saha T. An insight into the role of protein kinases as virulent factors, regulating pathogenic attributes in Candida albicans. Microb Pathog 2022; 164:105418. [DOI: 10.1016/j.micpath.2022.105418] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 01/21/2022] [Accepted: 01/21/2022] [Indexed: 11/26/2022]
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18
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Liao B, Ye X, Chen X, Zhou Y, Cheng L, Zhou X, Ren B. The two-component signal transduction system and its regulation in Candida albicans. Virulence 2021; 12:1884-1899. [PMID: 34233595 PMCID: PMC8274445 DOI: 10.1080/21505594.2021.1949883] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/13/2021] [Accepted: 06/18/2021] [Indexed: 02/08/2023] Open
Abstract
Candida albicans, which can cause superficial and life-threatening systemic infections, is the most common opportunistic fungal pathogen in the human microbiome. The two-component system is one of the most important C. albicans signal transduction pathways, regulating the response to oxidative and osmotic stresses, adhesion, morphogenesis, cell wall synthesis, virulence, drug resistance, and the host-pathogen interactions. Notably, some components of this signaling pathway have not been found in the human genome, indicating that the two-component system of C. albicans can be a potential target for new antifungal agents. Here, we summarize the composition, signal transduction, and regulation of the two-component system of C. albicans to emphasize its essential roles in the pathogenesis of C. albicans and the new therapeutic target for antifungal drugs.
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Affiliation(s)
- Biaoyou Liao
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
| | - Xingchen Ye
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
| | - Xi Chen
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yujie Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
- Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases& West China School of Stomatology, Sichuan University, Chengdu, China
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19
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Navarro MV, de Barros YN, Segura WD, Chaves AFA, Jannuzzi GP, Ferreira KS, Xander P, Batista WL. The Role of Dimorphism Regulating Histidine Kinase (Drk1) in the Pathogenic Fungus Paracoccidioides brasiliensis Cell Wall. J Fungi (Basel) 2021; 7:jof7121014. [PMID: 34946996 PMCID: PMC8707131 DOI: 10.3390/jof7121014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/09/2021] [Accepted: 11/24/2021] [Indexed: 11/16/2022] Open
Abstract
Dimorphic fungi of the Paracoccidioides genus are the causative agents of paracoccidioidomycosis (PCM), an endemic disease in Latin America with a high incidence in Brazil. This pathogen presents as infective mycelium at 25 °C in the soil, reverting to its pathogenic form when inhaled by the mammalian host (37 °C). Among these dimorphic fungal species, dimorphism regulating histidine kinase (Drk1) plays an essential role in the morphological transition. These kinases are present in bacteria and fungi but absent in mammalian cells and are important virulence and cellular survival regulators. Hence, the purpose of this study was to investigate the role of PbDrk1 in the cell wall modulation of P. brasiliensis. We observed that PbDrk1 participates in fungal resistance to different cell wall-disturbing agents by reducing viability after treatment with iDrk1. To verify the role of PbDRK1 in cell wall morphogenesis, qPCR results showed that samples previously exposed to iDrk1 presented higher expression levels of several genes related to cell wall modulation. One of them was FKS1, a β-glucan synthase that showed a 3.6-fold increase. Furthermore, confocal microscopy analysis and flow cytometry showed higher β-glucan exposure on the cell surface of P. brasiliensis after incubation with iDrk1. Accordingly, through phagocytosis assays, a significantly higher phagocytic index was observed in yeasts treated with iDrk1 than the control group, demonstrating the role of PbDrk1 in cell wall modulation, which then becomes a relevant target to be investigated. In parallel, the immune response profile showed increased levels of proinflammatory cytokines. Finally, our data strongly suggest that PbDrk1 modulates cell wall component expression, among which we can identify β-glucan. Understanding this signalling pathway may be of great value for identifying targets of antifungal molecular activity since HKs are not present in mammals.
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Affiliation(s)
- Marina Valente Navarro
- Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo 04023-062, Brazil;
| | - Yasmin Nascimento de Barros
- Department of Pharmaceutical Sciences, Federal University of São Paulo, Diadema 09913-030, Brazil; (Y.N.d.B.); (W.D.S.); (K.S.F.); (P.X.)
| | - Wilson Dias Segura
- Department of Pharmaceutical Sciences, Federal University of São Paulo, Diadema 09913-030, Brazil; (Y.N.d.B.); (W.D.S.); (K.S.F.); (P.X.)
| | | | - Grasielle Pereira Jannuzzi
- Department of Clinical and Toxicological Analyses, University of São Paulo, São Paulo 05508-000, Brazil;
| | - Karen Spadari Ferreira
- Department of Pharmaceutical Sciences, Federal University of São Paulo, Diadema 09913-030, Brazil; (Y.N.d.B.); (W.D.S.); (K.S.F.); (P.X.)
| | - Patrícia Xander
- Department of Pharmaceutical Sciences, Federal University of São Paulo, Diadema 09913-030, Brazil; (Y.N.d.B.); (W.D.S.); (K.S.F.); (P.X.)
| | - Wagner Luiz Batista
- Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo 04023-062, Brazil;
- Department of Pharmaceutical Sciences, Federal University of São Paulo, Diadema 09913-030, Brazil; (Y.N.d.B.); (W.D.S.); (K.S.F.); (P.X.)
- Correspondence: ; Tel.: +55-11-3319-3594; Fax: +55-11-3319-3300
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20
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Adenylyl Cyclase and Protein Kinase A Play Redundant and Distinct Roles in Growth, Differentiation, Antifungal Drug Resistance, and Pathogenicity of Candida auris. mBio 2021; 12:e0272921. [PMID: 34663094 PMCID: PMC8524339 DOI: 10.1128/mbio.02729-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Candida auris is a globally emerging multidrug-resistant fungal pathogen. Its pathogenicity-related signaling networks are largely unknown. Here, we characterized the pathobiological functions of the cyclic AMP (cAMP)/protein kinase A (PKA) signaling pathway in C. auris. We focused on adenylyl cyclase (CYR1), the PKA regulatory subunit (BCY1), and the PKA catalytic subunits (TPK1 and TPK2). We concluded that PKA acts both dependently and independently of Cyr1 in C. auris. Tpk1 and Tpk2 have major and minor roles, respectively, in PKA activity and functions. Both Cyr1 and PKA promote growth, thermotolerance, filamentous growth, and resistance to stress and antifungal drugs by regulating expression of multiple effector genes. In addition, Cyr1 and PKA subunits were involved in disinfectant resistance of C. auris. However, deletion of both TPK1 and TPK2 generally resulted in more severe defects than CYR1 deletion, indicating that Cyr1 and PKA play redundant and distinct roles. Notably, Tpk1 and Tpk2 have redundant but Cyr1-independent roles in haploid-to-diploid cell transition, which increases virulence of C. auris. However, Tpk1 and Tpk2 often play opposing roles in formation of biofilms and the cell wall components chitin and chitosan. Surprisingly, deletion of CYR1 or TPK1/TPK2, which resulted in severe in vitro growth defects at 37°C, did not attenuate virulence, and BCY1 deletion reduced virulence of C. auris in a systemic murine infection model. In conclusion, this study provides comprehensive insights into the role of the cAMP/PKA pathway in drug resistance and pathogenicity of C. auris and suggests a potential therapeutic option for treatment of C. auris-mediated candidemia.
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Alaalm L, Crunden JL, Butcher M, Obst U, Whealy R, Williamson CE, O'Brien HE, Schaffitzel C, Ramage G, Spencer J, Diezmann S. Identification and Phenotypic Characterization of Hsp90 Phosphorylation Sites That Modulate Virulence Traits in the Major Human Fungal Pathogen Candida albicans. Front Cell Infect Microbiol 2021; 11:637836. [PMID: 34513723 PMCID: PMC8431828 DOI: 10.3389/fcimb.2021.637836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 05/24/2021] [Indexed: 01/13/2023] Open
Abstract
The highly conserved, ubiquitous molecular chaperone Hsp90 is a key regulator of cellular proteostasis and environmental stress responses. In human pathogenic fungi, which kill more than 1.6 million patients each year worldwide, Hsp90 governs cellular morphogenesis, drug resistance, and virulence. Yet, our understanding of the regulatory mechanisms governing fungal Hsp90 function remains sparse. Post-translational modifications are powerful components of nature’s toolbox to regulate protein abundance and function. Phosphorylation in particular is critical in many cellular signaling pathways and errant phosphorylation can have dire consequences for the cell. In the case of Hsp90, phosphorylation affects its stability and governs its interactions with co-chaperones and clients. Thereby modulating the cell’s ability to cope with environmental stress. Candida albicans, one of the leading human fungal pathogens, causes ~750,000 life-threatening invasive infections worldwide with unacceptably high mortality rates. Yet, it remains unknown if and how Hsp90 phosphorylation affects C. albicans virulence traits. Here, we show that phosphorylation of Hsp90 is critical for expression of virulence traits. We combined proteomics, molecular evolution analyses and structural modeling with molecular biology to characterize the role of Hsp90 phosphorylation in this non-model pathogen. We demonstrated that phosphorylation negatively affects key virulence traits, such as the thermal stress response, morphogenesis, and drug susceptibility. Our results provide the first record of a specific Hsp90 phosphorylation site acting as modulator of fungal virulence. Post-translational modifications of Hsp90 could prove valuable in future exploitations as antifungal drug targets.
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Affiliation(s)
- Leenah Alaalm
- Department of Biology & Biochemistry, University of Bath, Bath, United Kingdom
| | - Julia L Crunden
- Department of Biology & Biochemistry, University of Bath, Bath, United Kingdom.,School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Mark Butcher
- School of Medicine, Dentistry and Nursing, University of Glasgow, Glasgow, United Kingdom
| | - Ulrike Obst
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Ryann Whealy
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | | | - Heath E O'Brien
- MRC Centre for Neuropsychiatric Genetics & Genomics, Division of Psychological Medicine & Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | | | - Gordon Ramage
- School of Medicine, Dentistry and Nursing, University of Glasgow, Glasgow, United Kingdom
| | - James Spencer
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Stephanie Diezmann
- Department of Biology & Biochemistry, University of Bath, Bath, United Kingdom.,School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
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Rana A, Gupta N, Thakur A. Post-transcriptional and translational control of the morphology and virulence in human fungal pathogens. Mol Aspects Med 2021; 81:101017. [PMID: 34497025 DOI: 10.1016/j.mam.2021.101017] [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: 02/11/2021] [Revised: 08/13/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022]
Abstract
Host-pathogen interactions at the molecular level are the key to fungal pathogenesis. Fungal pathogens utilize several mechanisms such as adhesion, invasion, phenotype switching and metabolic adaptations, to survive in the host environment and respond. Post-transcriptional and translational regulations have emerged as key regulatory mechanisms ensuring the virulence and survival of fungal pathogens. Through these regulations, fungal pathogens effectively alter their protein pool, respond to various stress, and undergo morphogenesis, leading to efficient and comprehensive changes in fungal physiology. The regulation of virulence through post-transcriptional and translational regulatory mechanisms is mediated through mRNA elements (cis factors) or effector molecules (trans factors). The untranslated regions upstream and downstream of the mRNA, as well as various RNA-binding proteins involved in translation initiation or circularization of the mRNA, play pivotal roles in the regulation of morphology and virulence by influencing protein synthesis, protein isoforms, and mRNA stability. Therefore, post-transcriptional and translational mechanisms regulating the morphology, virulence and drug-resistance processes in fungal pathogens can be the target for new therapeutics. With improved "omics" technologies, these regulatory mechanisms are increasingly coming to the forefront of basic biology and drug discovery. This review aims to discuss various modes of post-transcriptional and translation regulations, and how these mechanisms exert influence in the virulence and morphogenesis of fungal pathogens.
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Affiliation(s)
- Aishwarya Rana
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India
| | - Nidhi Gupta
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India
| | - Anil Thakur
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India.
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Min K, Jannace TF, Si H, Veeramah KR, Haley JD, Konopka JB. Integrative multi-omics profiling reveals cAMP-independent mechanisms regulating hyphal morphogenesis in Candida albicans. PLoS Pathog 2021; 17:e1009861. [PMID: 34398936 PMCID: PMC8389844 DOI: 10.1371/journal.ppat.1009861] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/26/2021] [Accepted: 08/02/2021] [Indexed: 12/24/2022] Open
Abstract
Microbial pathogens grow in a wide range of different morphologies that provide distinct advantages for virulence. In the fungal pathogen Candida albicans, adenylyl cyclase (Cyr1) is thought to be a master regulator of the switch to invasive hyphal morphogenesis and biofilm formation. However, faster growing cyr1Δ/Δ pseudorevertant (PR) mutants were identified that form hyphae in the absence of cAMP. Isolation of additional PR mutants revealed that their improved growth was due to loss of one copy of BCY1, the negative regulatory subunit of protein kinase A (PKA) from the left arm of chromosome 2. Furthermore, hyphal morphogenesis was improved in some of PR mutants by multigenic haploinsufficiency resulting from loss of large regions of the left arm of chromosome 2, including global transcriptional regulators. Interestingly, hyphal-associated genes were also induced in a manner that was independent of cAMP. This indicates that basal protein kinase A activity is an important prerequisite to induce hyphae, but activation of adenylyl cyclase is not needed. Instead, phosphoproteomic analysis indicated that the Cdc28 cyclin-dependent kinase and the casein kinase 1 family member Yck2 play key roles in promoting polarized growth. In addition, integrating transcriptomic and proteomic data reveals hyphal stimuli induce increased production of key transcription factors that contribute to polarized morphogenesis.
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Affiliation(s)
- Kyunghun Min
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
| | - Thomas F. Jannace
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
| | - Haoyu Si
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
| | - Krishna R. Veeramah
- Department of Ecology and Evolution, Stony Brook University (SUNY), Stony Brook, New York, United States of America
| | - John D. Haley
- Department of Pathology, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
- Biological Mass Spectrometry Shared Resource, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
| | - James B. Konopka
- Department of Microbiology and Immunology, Renaissance School of Medicine, Stony Brook University (SUNY), Stony Brook, New York, United States of America
- * E-mail:
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Chow EWL, Pang LM, Wang Y. From Jekyll to Hyde: The Yeast-Hyphal Transition of Candida albicans. Pathogens 2021; 10:pathogens10070859. [PMID: 34358008 PMCID: PMC8308684 DOI: 10.3390/pathogens10070859] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 06/30/2021] [Accepted: 07/05/2021] [Indexed: 12/22/2022] Open
Abstract
Candida albicans is a major fungal pathogen of humans, accounting for 15% of nosocomial infections with an estimated attributable mortality of 47%. C. albicans is usually a benign member of the human microbiome in healthy people. Under constant exposure to highly dynamic environmental cues in diverse host niches, C. albicans has successfully evolved to adapt to both commensal and pathogenic lifestyles. The ability of C. albicans to undergo a reversible morphological transition from yeast to filamentous forms is a well-established virulent trait. Over the past few decades, a significant amount of research has been carried out to understand the underlying regulatory mechanisms, signaling pathways, and transcription factors that govern the C. albicans yeast-to-hyphal transition. This review will summarize our current understanding of well-elucidated signal transduction pathways that activate C. albicans hyphal morphogenesis in response to various environmental cues and the cell cycle machinery involved in the subsequent regulation and maintenance of hyphal morphogenesis.
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Affiliation(s)
- Eve Wai Ling Chow
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
| | - Li Mei Pang
- National Dental Centre Singapore, National Dental Research Institute Singapore (NDRIS), 5 Second Hospital Ave, Singapore 168938, Singapore;
| | - Yue Wang
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Singapore;
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore 117597, Singapore
- Correspondence:
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Padder SA, Ramzan A, Tahir I, Rehman RU, Shah AH. Metabolic flexibility and extensive adaptability governing multiple drug resistance and enhanced virulence in Candida albicans. Crit Rev Microbiol 2021; 48:1-20. [PMID: 34213983 DOI: 10.1080/1040841x.2021.1935447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Commensal fungus-Candida albicans turn pathogenic during the compromised immunity of the host, causing infections ranging from superficial mucosal to dreadful systemic ones. C. albicans has evolved various adaptive measures which collectively contribute towards its enhanced virulence. Among fitness attributes, metabolic flexibility and vigorous stress response are essential for its pathogenicity and virulence. Metabolic flexibility provides a means for nutrient assimilation and growth in diverse host microenvironments and reduces the vulnerability of the pathogen to various antifungals besides evading host immune response(s). Inside the host micro-environments, C. albicans efficiently utilizes the multiple fermentable and non-fermentable carbon sources to sustain and proliferate in glucose deficit conditions. The utilization of alternative carbon sources further highlights the importance of understanding these pathways as the attractive and potential therapeutic target. A thorough understanding of metabolic flexibility and adaptation to environmental stresses is warranted to decipher in-depth insights into virulence and molecular mechanisms of fungal pathogenicity. In this review, we have attempted to provide a detailed and recent understanding of some key aspects of fungal biology. Particular focus will be placed on processes like nutrient assimilation and utilization, metabolic adaptability, virulence factors, and host immune response in C. albicans leading to its enhanced pathogenicity.
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Affiliation(s)
- Sajad Ahmad Padder
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Asiya Ramzan
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Inayatullah Tahir
- Departments of Botany, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Reiaz Ul Rehman
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Abdul Haseeb Shah
- Department of Bioresources, School of Biological Sciences, University of Kashmir, Srinagar, India
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26
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Barbosa A, Araújo D, Henriques M, Silva S. The combined application of the anti-RAS1 and anti-RIM101 2'-OMethylRNA oligomers enhances Candida albicans filamentation control. Med Mycol 2021; 59:1024-1031. [PMID: 34097057 DOI: 10.1093/mmy/myab033] [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: 02/19/2021] [Revised: 05/12/2021] [Accepted: 06/02/2021] [Indexed: 01/30/2023] Open
Abstract
Whereas antisense oligomers (ASOs) have been successfully utilized to control gene expression, they have been little exploited to control Candida albicans virulence's determinants. Filamentation is an important virulence factor of C. albicans, and RAS1 and RIM101 genes are involved in its regulation. Thus, the main goal of this work was to project ASOs, based on 2'-OMethyl chemical modification, to target RAS1 and RIM101 mRNA and to validate its application either alone or in combination, to reduce Candida filamentation in different human body fluids.It was verified that both, anti-RAS1 2'OMe and anti-RIM101 2'OMe oligomers, were able to reduce the levels of RAS1 and RIM101 genes' expression and to significantly reduce C. albicans filamentation. Furthermore, the combined application of anti-RAS1 2'OMe oligomer and anti-RIM101 2'OMe oligomer enhances the control of C. albicans filamentation in artificial saliva and urine.Our work confirms that ASOs are useful tools for research and therapeutic development on the control of candidiasis. LAY ABSTRACT This work aimed to project antisense oligomers to control Candida albicans filamentation. The results revealed that the projected oligomers, anti-RAS1 2'OMe and anti-RIM101 2'OMe, were able to control RAS1 and RIM101 gene expression and to significantly reduce C. albicans filamentation.
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Affiliation(s)
- Ana Barbosa
- LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Daniela Araújo
- LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Mariana Henriques
- LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
| | - Sónia Silva
- LIBRO - Laboratório de Investigação em Biofilmes Rosário Oliveira, CEB - Centre of Biological Engineering, University of Minho, 4710-057 Braga, Portugal
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Stępień Ł, Lalak-Kańczugowska J. Signaling pathways involved in virulence and stress response of plant-pathogenic Fusarium species. FUNGAL BIOL REV 2021. [DOI: 10.1016/j.fbr.2020.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
In the last decades, Candida albicans has served as the leading causal agent of life-threatening invasive infections with mortality rates approaching 40% despite treatment. Candida albicans (C. albicans) exists in three biological phases: yeast, pseudohyphae, and hyphae. Hyphae, which represent an important phase in the disease process, can cause tissue damage by invading mucosal epithelial cells then leading to blood infection. In this review, we summarized recent results from different fields of fungal cell biology that are instrumental in understanding hyphal growth. This includes research on the differences among C. albicans phases; the regulatory mechanism of hyphal growth, extension, and maintaining cutting-edge polarity; cross regulations of hyphal development and the virulence factors that cause serious infection. With a better understanding of the mechanism on mycelium formation, this review provides a theoretical basis for the identification of targets in candidiasis treatment. It also gives some reference to the study of antifungal drugs.
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Affiliation(s)
- Hui Chen
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, China.,Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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Loss of Arp1, a putative actin-related protein, triggers filamentous and invasive growth and impairs pathogenicity in Candida albicans. Comput Struct Biotechnol J 2020; 18:4002-4015. [PMID: 33363697 PMCID: PMC7744652 DOI: 10.1016/j.csbj.2020.11.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/19/2020] [Accepted: 11/21/2020] [Indexed: 12/27/2022] Open
Abstract
The polymorphous cellular shape of Candida albicans, in particular the transition from a yeast to a filamentous form, is crucial for either commensalism or life-threatening infections of the host. Various external or internal stimuli, including serum and nutrition starvation, have been shown to regulate filamentous growth primarily through two classical signaling pathways, the cAMP-PKA and the MAPK pathways. Genotoxic stress also induces filamentous growth, but through independent pathways, and little is known about negative regulation during this reversible morphological transition. In this study, we established that ARP1 in C. albicans, similar to its homolog in S. cerevisiae, has a role in nuclei separation and spindle orientation. Deletion of ARP1 generated filamentous and invasive growth as well as increased biofilm formation, accompanied by up-regulation of hyphae specific genes, such as HWP1, UME6 and ALS3. The filamentous and invasive growth of the ARP1 deletion strain was independent of transcription factors Efg1, Cph1 and Ume6, but was suppressed by deleting checkpoint BUB2 or overexpressing NRG1. Deletion of ARP1 impaired the colonization of Candida cells in mice and also attenuated virulence in a mouse model. All the data suggest that loss of ARP1 activates filamentous and invasive growth in vitro, and that it positively regulates virulence in vivo, which provides insight into actin-related morphology and pathogenicity in C. albicans.
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H89 Treatment Reduces Intestinal Inflammation and Candida albicans Overgrowth in Mice. Microorganisms 2020; 8:microorganisms8122039. [PMID: 33352792 PMCID: PMC7766101 DOI: 10.3390/microorganisms8122039] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/10/2020] [Accepted: 12/17/2020] [Indexed: 12/28/2022] Open
Abstract
Deregulation of the dynamic crosstalk between the gut microbiota, intestinal epithelial cells, and immune cells is critically involved in the development of inflammatory bowel disease and the overgrowth of opportunistic pathogens, including the human opportunistic fungus Candida albicans. In the present study, we assessed the effect of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor, on the migration of macrophages to C. albicans through dextran sulphate sodium (DSS)-challenged Caco-2 cells. We also investigated the impact of H89 on intestinal inflammation and C. albicans clearance from the gut, and determined the diversity of the gut microbiota in a murine model of DSS-induced colitis. H89 reduced the migration of macrophages to C. albicans through DSS-challenged Caco-2 cells. In addition, H89 decreased C. albicans viability and diminished the expression of pro-inflammatory cytokines and innate immune receptors in macrophages and colonic epithelial Caco-2 cells. In mice with DSS-induced colitis, H89 attenuated the clinical and histological scores of inflammation and promoted the elimination of C. albicans from the gut. H89 administration to mice decreased the overgrowth of Escherichia coli and Enterococcus faecalis populations while Lactobacillus johnsonii populations increased significantly. Overall, H89 reduced intestinal inflammation and promoted the elimination of C. albicans from the gut.
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Experimental Evolution Identifies Adaptive Aneuploidy as a Mechanism of Fluconazole Resistance in Candida auris. Antimicrob Agents Chemother 2020; 65:AAC.01466-20. [PMID: 33077664 DOI: 10.1128/aac.01466-20] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/14/2020] [Indexed: 12/22/2022] Open
Abstract
Candida auris is a newly emerging fungal pathogen of humans and has attracted considerable attention from both the clinical and basic research communities. Clinical isolates of C. auris are often resistant to one or more antifungal agents. To explore how antifungal resistance develops, we performed experimental evolution assays using a fluconazole-susceptible isolate of C. auris (BJCA001). After a series of passages through medium containing increasing concentrations of fluconazole, fungal cells acquired resistance. By sequencing and comparing the genomes of the parental fluconazole-susceptible strain and 26 experimentally evolved strains of C. auris, we found that a portion of fluconazole-resistant strains carried one extra copy of chromosome V. In the absence of fluconazole, C. auris cells rapidly became susceptible and lost the extra copy of chromosome V. Genomic and transcriptome sequencing (RNA-Seq) analyses indicate that this chromosome carries a number of drug resistance-related genes, which were transcriptionally upregulated in the resistant, aneuploid strains. Moreover, missense mutations were identified in the genes TAC1B, RRP6, and SFT2 in all experimentally evolved strains. Our findings suggest that the gain of an extra copy of chromosome V is associated with the rapid acquisition of fluconazole resistance and may represent an important evolutionary mechanism of antifungal resistance in C. auris.
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The Protein Kinase A-Dependent Phosphoproteome of the Human Pathogen Aspergillus fumigatus Reveals Diverse Virulence-Associated Kinase Targets. mBio 2020; 11:mBio.02880-20. [PMID: 33323509 PMCID: PMC7773993 DOI: 10.1128/mbio.02880-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PKA is essential for the virulence of eukaryotic human pathogens. Understanding PKA signaling mechanisms is therefore fundamental to deciphering pathogenesis and developing novel therapies. Protein kinase A (PKA) signaling plays a critical role in the growth and development of all eukaryotic microbes. However, few direct targets have been characterized in any organism. The fungus Aspergillus fumigatus is a leading infectious cause of death in immunocompromised patients, but the specific molecular mechanisms responsible for its pathogenesis are poorly understood. We used this important pathogen as a platform for a comprehensive and multifaceted interrogation of both the PKA-dependent whole proteome and phosphoproteome in order to elucidate the mechanisms through which PKA signaling regulates invasive microbial disease. Employing advanced quantitative whole-proteomic and phosphoproteomic approaches with two complementary phosphopeptide enrichment strategies, coupled to an independent PKA interactome analysis, we defined distinct PKA-regulated pathways and identified novel direct PKA targets contributing to pathogenesis. We discovered three previously uncharacterized virulence-associated PKA effectors, including an autophagy-related protein, Atg24; a CCAAT-binding transcriptional regulator, HapB; and a CCR4-NOT complex-associated ubiquitin ligase, Not4. Targeted mutagenesis, combined with in vitro kinase assays, multiple murine infection models, structural modeling, and molecular dynamics simulations, was employed to characterize the roles of these new PKA targets in growth, environmental and antimicrobial stress responses, and pathogenesis in a mammalian system. We also elucidated the molecular mechanisms of PKA regulation for these effectors by defining the functionality of phosphorylation at specific PKA target sites. We have comprehensively characterized the PKA-dependent phosphoproteome and validated PKA targets as direct regulators of infectious disease for the first time in any pathogen, providing new insights into PKA signaling and control over microbial pathogenesis.
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Liu J, Du Y, Ma H, Pei X, Li M. Enhancement of Monascus yellow pigments production by activating the cAMP signalling pathway in Monascus purpureus HJ11. Microb Cell Fact 2020; 19:224. [PMID: 33287814 PMCID: PMC7720387 DOI: 10.1186/s12934-020-01486-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Monascus azaphilone pigments (MonAzPs), which were produced by Monascus species, have been used as important food colorant and food supplements for more than one billion people during their daily life. Moreover, MonAzPs recently have received more attention because of their diverse physiological activities. However, the high microbial production of MonAzPs is still not always guaranteed. Herein, the aim of this study was to develop an efficient biotechnological process for MonAzPs production. RESULTS In this study, exogenous cyclic adenosine monophosphate (cAMP) treatment not only induced MonAzPs production, but also stimulated the expression of a cAMP phosphodiesterase gene, named as mrPDE, in M. purpureus HJ11. Subsequently, MrPDE was identified as a cAMP phosphodiesterase by in vitro enzymatic reaction with purified enzyme. Further, a gene knockout mutant of mrPDE was constructed to verify the activation of cAMP signalling pathway. Deletion of mrPDE in M. purpureus HJ11 improved cAMP concentration by 378% and enhanced PKA kinase activity 1.5-fold, indicating that activation of cAMP signalling pathway was achieved. The ΔmrPDE strain produced MonAzPs at 8563 U/g, with a 2.3-fold increase compared with the WT strain. Moreover, the NAPDH/NADP+ ratio of the ΔmrPDE strain was obviously higher than that of the wild type strain, which led to a higher proportion of yellow MonAzPs. With fed-batch fermentation of the ΔmrPDE strain, the production and yield of MonAzPs achieved 332.1 U/mL and 8739 U/g. CONCLUSIONS A engineered M. purpureus strain for high MonAzPs production was successfully developed by activating the cAMP signalling pathway. This study not only describes a novel strategy for development of MonAzPs-producing strain, but also provides a roadmap for engineering efforts towards the production of secondary metabolism in other filamentous fungi.
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Affiliation(s)
- Jiawei Liu
- Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, Key Laboratory of Environment Correlative Dietology, College of Food Science and Technology, Huazhong Agricultural University, Hubei Province, Wuhan, 430070, China
| | - Yun Du
- Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, Key Laboratory of Environment Correlative Dietology, College of Food Science and Technology, Huazhong Agricultural University, Hubei Province, Wuhan, 430070, China
| | - Hongmin Ma
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China
| | - Xiaolin Pei
- College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou, 310012, China
| | - Mu Li
- Hubei International Scientific and Technological Cooperation Base of Traditional Fermented Foods, Key Laboratory of Environment Correlative Dietology, College of Food Science and Technology, Huazhong Agricultural University, Hubei Province, Wuhan, 430070, China.
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N-Acetylglucosamine (GlcNAc) Sensing, Utilization, and Functions in Candida albicans. J Fungi (Basel) 2020; 6:jof6030129. [PMID: 32784532 PMCID: PMC7558947 DOI: 10.3390/jof6030129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 07/25/2020] [Accepted: 07/29/2020] [Indexed: 12/16/2022] Open
Abstract
The sensing and efficient utilization of environmental nutrients are critical for the survival of microorganisms in environments where nutrients are limited, such as within mammalian hosts. Candida albicans is a common member of the human microbiota as well as an opportunistic fungal pathogen. The amide derivative sugar N-acetlyglucosamine (GlcNAc) is an important signaling molecule for C. albicans that could be a major nutrient source for this fungus in host settings. In this article, we review progress made over the past two decades on GlcNAc utilization, sensing, and functions in C. albicans and its related fungal species. GlcNAc sensing and catabolic pathways have been intensively studied in C. albicans. The C. albicans protein Ngt1 represents the first identified GlcNAc-specific transporter in eukaryotic organisms. In C. albicans, GlcNAc not only induces morphological transitions including the yeast to hyphal transition and the white to opaque phenotypic switch, but it also promotes fungal cell death. The Ras-cAMP/PKA signaling pathway plays critical roles in regulating these processes. Given the importance of GlcNAc sensing and utilization in C. albicans, targeting GlcNAc associated pathways and key pathway components could be promising in the development of new antifungal strategies.
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A Set of Diverse Genes Influence the Frequency of White-Opaque Switching in Candida albicans. G3-GENES GENOMES GENETICS 2020; 10:2593-2600. [PMID: 32487674 PMCID: PMC7407467 DOI: 10.1534/g3.120.401249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The fungal species Candida albicans is both a member of the human microbiome and a fungal pathogen. C. albicans undergoes several different morphological transitions, including one called white-opaque switching. Here, cells reversibly switch between two states, “white” and “opaque,” and each state is heritable through many cell generations. Each cell type has a distinct cellular and colony morphology and they differ in many other properties including mating, nutritional specialization, and interactions with the innate immune system. Previous genetic screens to gain insight into white-opaque switching have focused on certain classes of genes (for example transcriptional regulators or chromatin modifying enzymes). In this paper, we examined 172 deletion mutants covering a broad range of cell functions. We identified 28 deletion mutants with at least a fivefold effect on switching frequencies; these cover a wide variety of functions ranging from membrane sensors to kinases to proteins of unknown function. In agreement with previous reports, we found that components of the pheromone signaling cascade affect white-to-opaque switching; however, our results suggest that the major effect of Cek1 on white-opaque switching occurs through the cell wall damage response pathway. Most of the genes we identified have not been previously implicated in white-opaque switching and serve as entry points to understand new aspects of this morphological transition.
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Liang W, Guan G, Li C, Nobile CJ, Tao L, Huang G. Genetic regulation of the development of mating projections in Candida albicans. Emerg Microbes Infect 2020; 9:413-426. [PMID: 32079510 PMCID: PMC7048184 DOI: 10.1080/22221751.2020.1729067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Candida albicans is a major human fungal pathogen, capable of switching among a range of morphological types, such as the yeast form, including white and opaque cell types and the GUT (gastrointestinally induced transition) cell type, the filamentous form, including hyphal and pseudohyphal cell types, and chlamydospores. This ability is associated with its commensal and pathogenic life styles. In response to pheromone, C. albicans cells are able to form long mating projections resembling filaments. This filamentous morphology is required for efficient sexual mating. In the current study, we report the genetic regulatory mechanisms controlling the development of mating projections in C. albicans. Ectopic expression of MTLα1 in “a” cells induces the secretion of α-pheromone and promotes the development of mating projections. Using this inducible system, we reveal that members of the pheromone-sensing pathway (including the pheromone receptor), the Ste11-Hst7-Cek1/2 mediated MAPK signalling cascade, and the RAM pathway are essential for the development of mating projections. However, the cAMP/PKA signalling pathway and a number of key regulators of filamentous growth such as Hgc1, Efg1, Flo8, Tec1, Ume6, and Rfg1 are not required for mating projection formation. Therefore, despite the phenotypic similarities between filaments and mating projections in C. albicans, distinct mechanisms are involved in the regulation of these two morphologies.
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Affiliation(s)
- Weihong Liang
- Department of infectious diseases, Huashan Hospital, Fudan University, Shanghai, People's Republic of China.,State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, People's Republic of China.,State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Guobo Guan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Chao Li
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Clarissa J Nobile
- Department of Molecular and Cell Biology, University of California, Merced, CA, USA
| | - Li Tao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Guanghua Huang
- Department of infectious diseases, Huashan Hospital, Fudan University, Shanghai, People's Republic of China.,State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, People's Republic of China
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Non-canonical signalling mediates changes in fungal cell wall PAMPs that drive immune evasion. Nat Commun 2019; 10:5315. [PMID: 31757950 PMCID: PMC6876565 DOI: 10.1038/s41467-019-13298-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 10/29/2019] [Indexed: 01/09/2023] Open
Abstract
To colonise their host, pathogens must counter local environmental and immunological challenges. Here, we reveal that the fungal pathogen Candida albicans exploits diverse host-associated signals to promote immune evasion by masking of a major pathogen-associated molecular pattern (PAMP), β-glucan. Certain nutrients, stresses and antifungal drugs trigger β-glucan masking, whereas other inputs, such as nitrogen sources and quorum sensing molecules, exert limited effects on this PAMP. In particular, iron limitation triggers substantial changes in the cell wall that reduce β-glucan exposure. This correlates with reduced phagocytosis by macrophages and attenuated cytokine responses by peripheral blood mononuclear cells. Iron limitation-induced β-glucan masking depends on parallel signalling via the iron transceptor Ftr1 and the iron-responsive transcription factor Sef1, and the protein kinase A pathway. Our data reveal that C. albicans exploits a diverse range of specific host signals to trigger protective anticipatory responses against impending phagocytic attack and promote host colonisation. The authors show that the fungal pathogen Candida albicans exploits diverse host-associated signals, including specific nutrients and stresses, to promote immune evasion by masking cell wall β-glucan, a major pathogen-associated molecular pattern.
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38
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Zhang Y, Liu H, Cao Q, Ge Q, Cui H, Yu X, Ye Z. Cloning and characterization of the UePrf1 gene in Ustilago esculenta. FEMS Microbiol Lett 2019; 365:4956762. [PMID: 29617942 DOI: 10.1093/femsle/fny081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/29/2018] [Indexed: 11/12/2022] Open
Abstract
Ustilago esculenta, an obligate parasite of Zizania latifolia, is a typical dimorphic fungus which induces host stem swelling and inhibits host inflorescence development, but is not found in host leaves. Previous studies have shown that dimorphic switching is essential for fungal pathogenicity and is regulated by protein kinase A and mitogen-activated protein kinase (MAPK) signaling pathways that are integrated by Prf1 in Ustilago maydis. In this study we identified a Prf1 homolog in U. esculenta, designated UePrf1, encoding 830 amino acids with a conserved high mobility group domain located between amino acids 124 and 195. UePrf1 was upregulated during the mating process, which induces dimorphism in U. esculenta. In vitro, UePrf1 mutants showed defects in the mating process, including cell fusion and hyphal growth. UePrf1 mutants also show reduced expression of a genes, even during the cell fusion process. Additionally, the defect in hyphal growth of the UeKpp2 and UeKpp6 mutants (MAPK signaling pathway mutants) was partially counteracted by UePrf1 overexpression, along with induced b gene expression. These results provide evidence that UePrf1 is a key factor coordinating dimorphism in U. esculenta and suggest a conserved role for UePrf1 in the regulation of the a and b genes.
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Affiliation(s)
- Yafen Zhang
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Honglei Liu
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Qianchao Cao
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Qianwen Ge
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Haifeng Cui
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Xiaoping Yu
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
| | - Zihong Ye
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang 310018, China
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39
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Leipheimer J, Bloom ALM, Panepinto JC. Protein Kinases at the Intersection of Translation and Virulence. Front Cell Infect Microbiol 2019; 9:318. [PMID: 31572689 PMCID: PMC6749009 DOI: 10.3389/fcimb.2019.00318] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/26/2019] [Indexed: 12/14/2022] Open
Abstract
As free living organisms, fungi are challenged with a variety of environmental insults that threaten their cellular processes. In some cases, these challenges mimic conditions present within mammals, resulting in the accidental selection of virulence factors over evolutionary time. Be it within a host or the soil, fungi must contend with environmental challenges through the production of stress effector proteins while maintaining factors required for viability in any condition. Initiation and upkeep of this balancing act is mainly under the control of kinases that affect the propensity and selectivity of protein translation. This review will focus on kinases in pathogenic fungi that facilitate a virulence phenotype through translational control.
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Affiliation(s)
- Jay Leipheimer
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
| | - Amanda L M Bloom
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
| | - John C Panepinto
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
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40
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Wang Y, Yan R, Tang L, Zhu L, Zhu D, Bai F. Dimorphism of Trichosporon cutaneum and impact on its lipid production. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:203. [PMID: 31485269 PMCID: PMC6714079 DOI: 10.1186/s13068-019-1543-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/10/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Compared to the oleaginous yeast Yarrowia lipolytica, Trichosporon cutaneum can metabolize pentose sugars more efficiently, and in the meantime is more tolerant to inhibitors, which is suitable for lipid production from lignocellulosic biomass. However, this species experiences dimorphic transition between yeast-form cells and hyphae during submerged fermentation, which consequently affects the rheology and mass transfer performance of the fermentation broth and its lipid production. RESULTS The strain T. cutaneum B3 was cultured with medium composed of yeast extract, glucose and basic minerals. The experimental results indicated that yeast-form morphology was developed when yeast extract was supplemented at 1 g/L, but hyphae were observed when yeast extract supplementation was increased to 3 g/L and 5 g/L, respectively. We speculated that difference in nitrogen supply to the medium might be a major reason for the dimorphic transition, which was confirmed by the culture with media supplemented with yeast extract at 1 g/L and urea at 0.5 g/L and 1.0 g/L to maintain total nitrogen at same levels as that detected in the media with yeast extract supplemented at 3 g/L and 5 g/L. The morphological change of T. cutaneum B3 affected not only the content of intracellular lipids but also their composition, due to its impact on the rheology and oxygen mass transfer performance of the fermentation broth, and more lipids with less polyunsaturated fatty acids such as linoleic acid (C18:2) were produced by the yeast-form cells. When T. cutaneum B3 was cultured at an aeration rate of 1.5 vvm for 72 h with the medium composed of 60 g/L glucose, 3 g/L yeast extract and basic minerals, 27.1 g (dry cell weight)/L biomass was accumulated with the lipid content of 46.2%, and lipid productivity and yield were calculated to be 0.174 g/L/h and 0.21 g/g, respectively. Comparative transcriptomics analysis identified differently expressed genes for sugar metabolism and lipid synthesis as well as signal transduction for the dimorphic transition of T. cutaneum B3. CONCLUSIONS Assimilable nitrogen was validated as one of the major reasons for the dimorphic transition between yeast-form morphology and hyphae with T. cutaneum, and the yeast-form morphology was more suitable for lipid production at high content with less polyunsaturated fatty acids as feedstock for biodiesel production.
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Affiliation(s)
- Ya Wang
- State Key Laboratory of Microbial Metabolism & School of Life Science and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai, 200240 China
| | - Riming Yan
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, School of Life Science, Jiangxi Normal University, 99 Ziyang Rd., Nanchang, 330022 China
| | - Lijuan Tang
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, School of Life Science, Jiangxi Normal University, 99 Ziyang Rd., Nanchang, 330022 China
| | - Libin Zhu
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, School of Life Science, Jiangxi Normal University, 99 Ziyang Rd., Nanchang, 330022 China
| | - Du Zhu
- School of Life Science, Jiangxi Science and Technology Normal University, 605 Fenglin Rd., Nanchang, 330013 China
- Key Laboratory of Protection and Utilization of Subtropic Plant Resources of Jiangxi Province, School of Life Science, Jiangxi Normal University, 99 Ziyang Rd., Nanchang, 330022 China
| | - Fengwu Bai
- State Key Laboratory of Microbial Metabolism & School of Life Science and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Rd., Shanghai, 200240 China
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41
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Comprehensive Analysis of Aspergillus nidulans PKA Phosphorylome Identifies a Novel Mode of CreA Regulation. mBio 2019; 10:mBio.02825-18. [PMID: 31040248 PMCID: PMC6495382 DOI: 10.1128/mbio.02825-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The cyclic AMP (cAMP)-dependent protein kinase A (PKA) signaling pathway is well conserved across eukaryotes, and previous work has shown that it plays an important role in regulating development, growth, and virulence in a number of fungi. PKA is activated in response to extracellular nutrients and acts to regulate metabolism and growth. While a number of components in the PKA pathway have been defined in filamentous fungi, current understanding does not provide a global perspective on PKA function. Thus, this work is significant in that it comprehensively identifies proteins and functional pathways regulated by PKA in a model filamentous fungus. This information enhances our understanding of PKA action and may provide information on how to manipulate it for specific purposes. In filamentous fungi, an important kinase responsible for adaptation to changes in available nutrients is cyclic AMP (cAMP)-dependent protein kinase (protein kinase A [PKA]). This kinase has been well characterized at a molecular level, but its systemic action and direct/indirect targets are generally not well understood in filamentous fungi. In this work, we used a pkaA deletion strain (ΔpkaA) to identify Aspergillus nidulans proteins for which phosphorylation is dependent (either directly or indirectly) on PKA. A combination of phosphoproteomic and transcriptomic analyses revealed both direct and indirect targets of PKA and provided a global perspective on its function. One of these targets was the transcription factor CreA, the main repressor responsible for carbon catabolite repression (CCR). In the ΔpkaA strain, we identified a previously unreported phosphosite in CreA, S319, which (based on motif analysis) appears to be a direct target of Stk22 kinase (AN5728). Upon replacement of CreA S319 with an alanine (i.e., phosphonull mutant), the dynamics of CreA import to the nucleus are affected. Collectively, this work provides a global overview of PKA function while also providing novel insight regarding significance of a specific PKA-mediated phosphorylation event.
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42
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Guan G, Tao L, Yue H, Liang W, Gong J, Bing J, Zheng Q, Veri AO, Fan S, Robbins N, Cowen LE, Huang G. Environment-induced same-sex mating in the yeast Candida albicans through the Hsf1-Hsp90 pathway. PLoS Biol 2019; 17:e2006966. [PMID: 30865631 PMCID: PMC6415874 DOI: 10.1371/journal.pbio.2006966] [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: 06/13/2018] [Accepted: 02/13/2019] [Indexed: 12/14/2022] Open
Abstract
While sexual reproduction is pervasive in eukaryotic cells, the strategies employed by fungal species to achieve and complete sexual cycles is highly diverse and complex. Many fungi, including Saccharomyces cerevisiae and Schizosaccharomyces pombe, are homothallic (able to mate with their own mitotic descendants) because of homothallic switching (HO) endonuclease-mediated mating-type switching. Under laboratory conditions, the human fungal pathogen Candida albicans can undergo both heterothallic and homothallic (opposite- and same-sex) mating. However, both mating modes require the presence of cells with two opposite mating types (MTLa/a and α/α) in close proximity. Given the predominant clonal feature of this yeast in the human host, both opposite- and same-sex mating would be rare in nature. In this study, we report that glucose starvation and oxidative stress, common environmental stresses encountered by the pathogen, induce the development of mating projections and efficiently permit same-sex mating in C. albicans with an "a" mating type (MTLa/a). This induction bypasses the requirement for the presence of cells with an opposite mating type and allows efficient sexual mating between cells derived from a single progenitor. Glucose starvation causes an increase in intracellular oxidative species, overwhelming the Heat Shock transcription Factor 1 (Hsf1)- and Heat shock protein (Hsp)90-mediated stress-response pathway. We further demonstrate that Candida TransActivating protein 4 (Cta4) and Cell Wall Transcription factor 1 (Cwt1), downstream effectors of the Hsf1-Hsp90 pathway, regulate same-sex mating in C. albicans through the transcriptional control of the master regulator of a-type mating, MTLa2, and the pheromone precursor-encoding gene Mating α factor precursor (MFα). Our results suggest that mating could occur much more frequently in nature than was originally appreciated and that same-sex mating could be an important mode of sexual reproduction in C. albicans.
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Affiliation(s)
- Guobo Guan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Li Tao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Huizhen Yue
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Weihong Liang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jiao Gong
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jian Bing
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Qiushi Zheng
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Amanda O Veri
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Shuru Fan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - 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
| | - Guanghua Huang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
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Chang C, Cai E, Deng YZ, Mei D, Qiu S, Chen B, Zhang LH, Jiang Z. cAMP/PKA signalling pathway regulates redox homeostasis essential for Sporisorium scitamineum mating/filamentation and virulence. Environ Microbiol 2019; 21:959-971. [PMID: 30537399 DOI: 10.1111/1462-2920.14496] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 11/29/2018] [Accepted: 12/01/2018] [Indexed: 12/27/2022]
Abstract
The fungal pathogen Sporisorium scitamineum causes sugarcane smut disease. The formation and growth of dikaryotic hypha after sexual mating is critical for S. scitamineum pathogenicity, however regulation of S. scitimineum mating has not been studied in detail. We identified and characterized the core components of the conserved cAMP/PKA pathway in S. scitamineum by reverse genetics. Our results showed that cAMP/PKA signalling pathway is essential for proper mating and filamentation, and thus critical for S. scitamineum virulence. We further demonstrated that an elevated intracellular ROS (reactive oxygen species) level promotes S. scitamineum mating-filamentation, via transcriptional regulation of ROS catabolic enzymes, and is under regulation of the cAMP/PKA signalling pathway. Furthermore, we found that fungal cAMP/PKA signalling pathway is also involved in regulation of host ROS response. Overall, our work displayed a positive role of elevated intracellular ROS in fungal differentiation and virulence.
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Affiliation(s)
- Changqing Chang
- Guangdong Innovative and Entepreneurial Research Team of Sociomicrobiology Basic Science and Frontier Technology, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, Peoples' Republic of China.,Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Enping Cai
- Guangdong Innovative and Entepreneurial Research Team of Sociomicrobiology Basic Science and Frontier Technology, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, Peoples' Republic of China.,Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Yi Zhen Deng
- Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Dan Mei
- Guangdong Innovative and Entepreneurial Research Team of Sociomicrobiology Basic Science and Frontier Technology, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, Peoples' Republic of China.,Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Shanxu Qiu
- Guangdong Innovative and Entepreneurial Research Team of Sociomicrobiology Basic Science and Frontier Technology, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, Peoples' Republic of China.,Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Baoshan Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Lian-Hui Zhang
- Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Zide Jiang
- Department of Plant Pathology, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
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Chen S, Xia J, Li C, Zuo L, Wei X. The possible molecular mechanisms of farnesol on the antifungal resistance of C. albicans biofilms: the regulation of CYR1 and PDE2. BMC Microbiol 2018; 18:203. [PMID: 30509171 PMCID: PMC6278051 DOI: 10.1186/s12866-018-1344-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/16/2018] [Indexed: 12/19/2022] Open
Abstract
Background Farnesol has potential antifungal activity against Candida albicans biofilms, but the molecular mechanism of this activity is still unclear. Farnesol inhibits hyphal growth by regulating the cyclic AMP (cAMP) signalling pathway in C. albicans, and CYR1 and PDE2 regulate a pair of enzymes that are directly responsible for cAMP synthesis and degradation. Here, we hypothesize that farnesol enhances the antifungal susceptibility of C. albicans biofilms by regulating CYR1 and PDE2. Results The resistance of the CYR1- and PDE2-overexpressing strains to caspofungin, itraconazole and terbinafine was increased in planktonic cells, and that to amphotericin B was increased in biofilms. Meanwhile, the biofilms of the CYR1- and PDE2-overexpressing strains were thicker (all p < 0.05) and consisted of more hyphae than that of the wild strain. The intracellular cAMP levels were higher in the biofilms of the CYR1-overexpressing strain than that in the biofilms of the wild strain (all p < 0.01), while no changes were found in the PDE2-overexpressing strain. Exogenous farnesol decreased the resistance of the CYR1- and PDE2-overexpressing strains to these four antifungals, repressed the hyphal and biofilm formation of the strains, and decreased the intracellular cAMP level in the biofilms (all p < 0.05) compared to the untreated controls. In addition, farnesol decreased the expression of the gene CYR1 and the protein CYR1 in biofilms of the CYR1-overexpressing strain (all p < 0.05) but increased the expression of the gene PDE2 and the protein PDE2 in biofilms of the PDE2-overexpressing strain (all p < 0.01). Conclusions The results indicate that CYR1 and PDE2 regulate the resistance of C. albicans biofilms to antifungals. Farnesol suppresses the resistance of C. albicans biofilms to antifungals by regulating the expression of the gene CYR1 and PDE2, while PDE2 regulation was subordinate to CYR1 regulation.
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Affiliation(s)
- Shengyan Chen
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Jinping Xia
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Chengxi Li
- Suzhou Hospital Affiliated to Nanjing Medical University, Suzhou Science and Technology Town Hospital, Suzhou, 215153, China
| | - Lulu Zuo
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China.,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China
| | - Xin Wei
- Jiangsu Key Laboratory of Oral Diseases, Nanjing Medical University, Nanjing, 210029, China. .,Department of Oral Medicine, Stomatology Hospital Affiliated to Nanjing Medical University, Nanjing, 210029, China.
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45
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Hypoxia Promotes Immune Evasion by Triggering β-Glucan Masking on the Candida albicans Cell Surface via Mitochondrial and cAMP-Protein Kinase A Signaling. mBio 2018; 9:mBio.01318-18. [PMID: 30401773 PMCID: PMC6222127 DOI: 10.1128/mbio.01318-18] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Organisms must adapt to changes in oxygen tension if they are to exploit the energetic benefits of reducing oxygen while minimizing the potentially damaging effects of oxidation. Consequently, organisms in all eukaryotic kingdoms display robust adaptation to hypoxia (low oxygen levels). This is particularly important for fungal pathogens that colonize hypoxic niches in the host. We show that adaptation to hypoxia in the major fungal pathogen of humans Candida albicans includes changes in cell wall structure and reduced exposure, at the cell surface, of β-glucan, a key pathogen-associated molecular pattern (PAMP). This leads to reduced phagocytosis by murine bone marrow-derived macrophages and decreased production of IL-10, RANTES, and TNF-α by peripheral blood mononuclear cells, suggesting that hypoxia-induced β-glucan masking has a significant effect upon C. albicans-host interactions. We show that hypoxia-induced β-glucan masking is dependent upon both mitochondrial and cAMP-protein kinase A (PKA) signaling. The decrease in β-glucan exposure is blocked by mutations that affect mitochondrial functionality (goa1Δ and upc2Δ) or that decrease production of hydrogen peroxide in the inner membrane space (sod1Δ). Furthermore, β-glucan masking is enhanced by mutations that elevate mitochondrial reactive oxygen species (aox1Δ). The β-glucan masking defects displayed by goa1Δ and upc2Δ cells are suppressed by exogenous dibutyryl-cAMP. Also, mutations that inactivate cAMP synthesis (cyr1Δ) or PKA (tpk1Δ tpk2Δ) block the masking phenotype. Our data suggest that C. albicans responds to hypoxic niches by inducing β-glucan masking via a mitochondrial cAMP-PKA signaling pathway, thereby modulating local immune responses and promoting fungal colonization.IMPORTANCE Animal, plant, and fungal cells occupy environments that impose changes in oxygen tension. Consequently, many species have evolved mechanisms that permit robust adaptation to these changes. The fungal pathogen Candida albicans can colonize hypoxic (low oxygen) niches in its human host, such as the lower gastrointestinal tract and inflamed tissues, but to colonize its host, the fungus must also evade local immune defenses. We reveal, for the first time, a defined link between hypoxic adaptation and immune evasion in C. albicans As this pathogen adapts to hypoxia, it undergoes changes in cell wall structure that include masking of β-glucan at its cell surface, and it becomes better able to evade phagocytosis by innate immune cells. We also define the signaling mechanisms that mediate hypoxia-induced β-glucan masking, showing that they are dependent on mitochondrial signaling and the cAMP-protein kinase pathway. Therefore, hypoxia appears to trigger immune evasion in this fungal pathogen.
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Huang G, Huang Q, Wei Y, Wang Y, Du H. Multiple roles and diverse regulation of the Ras/cAMP/protein kinase A pathway in Candida albicans. Mol Microbiol 2018; 111:6-16. [PMID: 30299574 DOI: 10.1111/mmi.14148] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2018] [Indexed: 01/15/2023]
Abstract
Candida albicans is a major fungal pathogen of humans, causing both superficial and life-threatening systemic infections in immunocompromised people. The conserved Ras/cAMP/PKA pathway plays a key role in regulating multiple traits important for the virulence of C. albicans such as cell growth, yeast-hyphal transition, white-opaque switching, sexual reproduction and biofilm development. Diverse external signals influence cell physiology by activating this signaling pathway. The key components of the Ras/cAMP/PKA pathway include two Ras GTPases (Ras1 and Ras2), an adenylyl cyclase (Cyr1, also known as Cdc35), two cyclic nucleotide phosphodiesterases (Pde1 and Pde2) and the catalytic (Tpk1 and Tpk2) and regulatory (Bcy1) subunits of PKA kinase. Activation of this pathway dramatically alters the gene expression profile via several transcription factors, leading to the activation of specific biological processes. Here, we review the progress made in the past two decades to elucidate the molecular mechanisms by which the Ras/cAMP/PKA pathway senses diverse environmental cues and controls specific cellular responses and its connection with other signaling pathways in C. albicans.
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Affiliation(s)
- Guanghua Huang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qian Huang
- Department of Dermatology, Affiliated Hospital of Guizhou Medical University, Guiyang, 550025, China
| | - Yujia Wei
- Department of Dermatology, Affiliated Hospital of Guizhou Medical University, Guiyang, 550025, China
| | - Yue Wang
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore, 138673, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore
| | - Han Du
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200438, China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
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Chen C, Zeng G, Wang Y. G1 and S phase arrest in Candida albicans induces filamentous growth via distinct mechanisms. Mol Microbiol 2018; 110:191-203. [PMID: 30084240 DOI: 10.1111/mmi.14097] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 07/26/2018] [Accepted: 07/30/2018] [Indexed: 01/07/2023]
Abstract
Candida albicans is an opportunistic fungal pathogen. In immunocompromised individuals, it can cause bloodstream infections with high mortality rates. The ability to switch between yeast and hyphal morphologies is a critical virulence factor of C. albicans. In response to diverse environmental cues, several signaling pathways are activated resulting in filamentous growth. Interestingly, cell cycle arrest can also trigger filamentous growth although the pathways involved are not well-understood. Here, we demonstrate that the cAMP-PKA pathway is involved in the filamentous growth caused by G1 arrest due to the depletion of the G1 cyclin Cln3 and S phase arrest due to hydroxyurea treatment. The downstream mechanisms involved in filamentation are different between the two cell cycle arrest phenomena. Cln3-depleted cells require HGC1 and UME6 for filamentous growth, but hydroxyurea-induced filamentation does not. Also, the hyphal repressor Nrg1 is not involved in the suppression of Cln3-depletion and hydroxyurea-induced filamentous growth. The findings highlight the complexity of the signaling networks that control filamentous growth in which different mechanisms downstream of the cAMP-PKA pathway are activated based on the nature of the inducing signals.
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Affiliation(s)
- Cuilan Chen
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Guisheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, Singapore.,Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Lin CJ, Chen YL. Conserved and Divergent Functions of the cAMP/PKA Signaling Pathway in Candida albicans and Candida tropicalis. J Fungi (Basel) 2018; 4:E68. [PMID: 29890663 PMCID: PMC6023519 DOI: 10.3390/jof4020068] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/28/2018] [Accepted: 06/07/2018] [Indexed: 01/03/2023] Open
Abstract
Fungal species undergo many morphological transitions to adapt to changing environments, an important quality especially in fungal pathogens. For decades, Candida albicans has been one of the most prevalent human fungal pathogens, and recently, the prevalence of Candida tropicalis as a causative agent of candidiasis has increased. In C. albicans, the ability to switch between yeast and hyphal forms is thought to be a key virulence factor and is regulated by multiple signaling cascades—including the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), calcineurin, high-osmolarity glycerol (HOG), and mitogen-activated protein kinases (MAPK) signaling pathways—upon receiving environmental cues. The cAMP/PKA signaling pathway also triggers white-opaque switching in C. albicans. However, studies on C. tropicalis morphogenesis are limited. In this minireview, we discuss the regulation of the yeast-hypha transition, virulence, and white-opaque switching through the cAMP/PKA pathway in the closely related species C. albicans and C. tropicalis.
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Affiliation(s)
- Chi-Jan Lin
- Department of Plant Pathology and Microbiology, National Taiwan University, 10617 Taipei, Taiwan.
| | - Ying-Lien Chen
- Department of Plant Pathology and Microbiology, National Taiwan University, 10617 Taipei, Taiwan.
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Kumar A. A fungus among us: The emerging opportunistic pathogen Candida tropicalis and PKA signaling. Virulence 2018; 9:659-661. [PMID: 29436900 PMCID: PMC5955444 DOI: 10.1080/21505594.2018.1438026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Anuj Kumar
- a Department of Molecular , Cellular, and Developmental Biology and Program in Cellular and Molecular Biology; University of Michigan ; Ann Arbor , MI , USA
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Basso V, d'Enfert C, Znaidi S, Bachellier-Bassi S. From Genes to Networks: The Regulatory Circuitry Controlling Candida albicans Morphogenesis. Curr Top Microbiol Immunol 2018; 422:61-99. [PMID: 30368597 DOI: 10.1007/82_2018_144] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Candida albicans is a commensal yeast of most healthy individuals, but also one of the most prevalent human fungal pathogens. During adaptation to the mammalian host, C. albicans encounters different niches where it is exposed to several types of stress, including oxidative, nitrosative (e.g., immune system), osmotic (e.g., kidney and oral cavity) stresses and pH variation (e.g., gastrointestinal (GI) tract and vagina). C. albicans has developed the capacity to respond to the environmental changes by modifying its morphology, which comprises the yeast-to-hypha transition, white-opaque switching, and chlamydospore formation. The yeast-to-hypha transition has been very well characterized and was shown to be modulated by several external stimuli that mimic the host environment. For instance, temperature above 37 ℃, serum, alkaline pH, and CO2 concentration are all reported to enhance filamentation. The transition is characterized by the activation of an intricate regulatory network of signaling pathways, involving many transcription factors. The regulatory pathways that control either the stress response or morphogenesis are required for full virulence and promote survival of C. albicans in the host. Many of these transcriptional circuitries have been characterized, highlighting the complexity and the interconnections between the different pathways. Here, we present the major signaling pathways and the main transcription factors involved in the yeast-to-hypha transition. Furthermore, we describe the role of heat shock transcription factors in the morphogenetic transition, providing an edifying example of the complex cross talk between pathways involved in morphogenesis and stress response.
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Affiliation(s)
- Virginia Basso
- Unité Biologie et Pathogénicité Fongiques, Institut Pasteur, INRA, 25 Rue Du Docteur Roux, 75015, Paris, France.,Univ. Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, 25 Rue Du Docteur Roux, Paris, France.,Department of Pathology and Laboratory Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Christophe d'Enfert
- Unité Biologie et Pathogénicité Fongiques, Institut Pasteur, INRA, 25 Rue Du Docteur Roux, 75015, Paris, France
| | - Sadri Znaidi
- Unité Biologie et Pathogénicité Fongiques, Institut Pasteur, INRA, 25 Rue Du Docteur Roux, 75015, Paris, France. .,Institut Pasteur de Tunis, University of Tunis El Manar, Laboratoire de Microbiologie Moléculaire, Vaccinologie et Développement Biotechnologique, 13 Place Pasteur, 1002, Tunis-Belvédère, Tunisia.
| | - Sophie Bachellier-Bassi
- Unité Biologie et Pathogénicité Fongiques, Institut Pasteur, INRA, 25 Rue Du Docteur Roux, 75015, Paris, France.
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