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Deng Y, Xu M, Li S, Bing J, Zheng Q, Huang G, Liao W, Pan W, Tao L. A single gene mutation underpins metabolic adaptation and acquisition of filamentous competence in the emerging fungal pathogen Candida auris. PLoS Pathog 2024; 20:e1012362. [PMID: 38976759 PMCID: PMC11257696 DOI: 10.1371/journal.ppat.1012362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 07/18/2024] [Accepted: 06/20/2024] [Indexed: 07/10/2024] Open
Abstract
Filamentous cell growth is a vital property of fungal pathogens. The mechanisms of filamentation in the emerging multidrug-resistant fungal pathogen Candida auris are poorly understood. Here, we show that exposure of C. auris to glycerol triggers a rod-like filamentation-competent (RL-FC) phenotype, which forms elongated filamentous cells after a prolonged culture period. Whole-genome sequencing analysis reveals that all RL-FC isolates harbor a mutation in the C2H2 zinc finger transcription factor-encoding gene GFC1 (Gfc1 variants). Deletion of GFC1 leads to an RL-FC phenotype similar to that observed in Gfc1 variants. We further demonstrate that GFC1 mutation causes enhanced fatty acid β-oxidation metabolism and thereby promotes RL-FC/filamentous growth. This regulation is achieved through a Multiple Carbon source Utilizer (Mcu1)-dependent mechanism. Interestingly, both the evolved RL-FC isolates and the gfc1Δ mutant exhibit an enhanced ability to colonize the skin. Our results reveal that glycerol-mediated GFC1 mutations are beneficial during C. auris skin colonization and infection.
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Affiliation(s)
- Yuchen Deng
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Ming Xu
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Shuaihu Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Jian Bing
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Qiushi Zheng
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Guanghua Huang
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
| | - Wanqing Liao
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Weihua Pan
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Second Affiliated Hospital of Naval Medical University, Shanghai, China
| | - Li Tao
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Department of Infectious Diseases, Huashan Hospital, Fudan University, Shanghai, China
- Department of Dermatology, Shanghai Key Laboratory of Molecular Medical Mycology, Second Affiliated Hospital of Naval Medical University, Shanghai, China
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2
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Woodruff AL, Berman J, Anderson M. Strain background of Candida albicans interacts with SIR2 to alter phenotypic switching. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001444. [PMID: 38446018 PMCID: PMC10999749 DOI: 10.1099/mic.0.001444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 02/15/2024] [Indexed: 03/07/2024]
Abstract
The genetic background between strains of a single species and within a single strain lineage can significantly impact the expression of biological traits. This genetic variation may also reshape epigenetic mechanisms of cell identity and environmental responses that are controlled by interconnected transcriptional networks and chromatin-modifying enzymes. Histone deacetylases, including sirtuins, are critical regulators of chromatin state and have been directly implicated in governing the phenotypic transition between the 'sterile' white state and the mating-competent opaque state in Candida albicans, a common fungal commensal and pathogen of humans. Here, we found that a previously ambiguous role for the sirtuin SIR2 in C. albicans phenotypic switching is likely linked to the genetic background of mutant strains produced in the RM lineage of SC5314. SIR2 mutants in a specific lineage of BWP17 displayed increased frequencies of switching to the opaque state compared to the wild-type. Loss of SIR2 in other SC5314-derived backgrounds, including newly constructed BWP17 sir2Δ/Δ mutants, failed to recapitulate the increased white-opaque switching frequencies observed in the original BWP17 sir2Δ/Δ mutant background. Whole-genome sequencing revealed the presence of multiple imbalanced chromosomes and large loss of heterozygosity tracts that likely interact with SIR2 to increase phenotypic switching in this BWP17 sir2Δ/Δ mutant lineage. These genomic changes are not found in other SC5314-derived sir2Δ/Δ mutants that do not display increased opaque cell formation. Thus, complex karyotypes can emerge during strain construction that modify mutant phenotypes and highlight the importance of validating strain background when interpreting phenotypes.
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Affiliation(s)
- Andrew L. Woodruff
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
| | - Judith Berman
- Shmunis School of Biomedical and Cancer Research, The George S Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Matthew Anderson
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Medical Genetics, Laboratory of Genetics, University of Wisconsin – Madison, Madison, WI, 53706, USA
- Center for Genomic Science Innovation, University of Wisconsin – Madison, Madison, WI, 53706, USA
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3
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Janeczko M, Kochanowicz E, Górka K, Skrzypek T. Quinalizarin as a potential antifungal drug for the treatment of Candida albicans fungal infection in cancer patients. Microbiol Spectr 2024; 12:e0365223. [PMID: 38289929 PMCID: PMC10913734 DOI: 10.1128/spectrum.03652-23] [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: 10/12/2023] [Accepted: 12/18/2023] [Indexed: 02/01/2024] Open
Abstract
This study aims to analyze the antifungal properties of quinalizarin, a plant-derived compound with proven anticancer effects. Quinalizarin exhibited antifungal activity against opportunistic pathogenic Candida species and Geotrichum capitatum. The treatment with this anthraquinone reduced hyphal growth, inhibited biofilm formation, and damaged mature Candida albicans biofilms. Real-time RT-PCR revealed that quinalizarin downregulated the expression of hyphae-related and biofilm-specific genes. The flow cytometry method used in the study showed that both apoptosis and necrosis were the physiological mechanisms of quinalizarin-induced C. albicans cell death, depending on the dose of the antifungal agent. A further study revealed an increase in the levels of intracellular reactive oxygen species and alterations in mitochondrial membrane potential after treatment with quinalizarin. Finally, quinalizarin was found to have low toxicity in a hemolytic test using human erythrocytes. In conclusion, we have identified quinalizarin as a potential antifungal compound.IMPORTANCEThis article is a study to determine the antifungal activity of quinalizarin (1,2,5,8-tetrahydroxyanthraquinone). Quinalizarin has potential antitumor properties and is effective in different types of tumor cells. The aim of the present study was to prove that quinalizarin can be used simultaneously in the treatment of cancer and in the treatment of intercurrent fungal infections. Quinalizarin was identified as a novel antifungal compound with low toxicity. These results may contribute to the development of a new drug with dual activity in the treatment of cancer-associated candidiasis.
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Affiliation(s)
- Monika Janeczko
- Department of Molecular Biology, Faculty of Medicine, The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Elżbieta Kochanowicz
- Department of Molecular Biology, Faculty of Medicine, The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Kamila Górka
- Department of Molecular Biology, Faculty of Medicine, The John Paul II Catholic University of Lublin, Lublin, Poland
| | - Tomasz Skrzypek
- Department of Biomedicine and Environmental Research, Faculty of Medicine, The John Paul II Catholic University of Lublin, Lublin, Poland
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4
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Guan G, Li S, Bing J, Liu L, Tao L. The Rfg1 and Bcr1 transcription factors regulate acidic pH-induced filamentous growth in Candida albicans. Microbiol Spectr 2023; 11:e0178923. [PMID: 37933972 PMCID: PMC10715123 DOI: 10.1128/spectrum.01789-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 09/23/2023] [Indexed: 11/08/2023] Open
Abstract
IMPORTANCE Candida albicans is a human commensal and frequent pathogen that encounters a wide range of pH stresses. The ability of C. albicans to adapt to changes in extracellular pH is crucial for its success in colonization and pathogenesis. The Rim101 pH sensing pathway is well known to govern neutral-alkaline pH responses in this pathogen. Here, we report a novel Rfg1-Bcr1 regulatory pathway that governs acidic pH responses and regulates filamentous growth in C. albicans. In addition, the Rim101-Phr1 pathway, cAMP signaling pathway, transcription factors Efg1 and Flo8, and hyphal-specific G1 cyclin Hgc1 cooperate with this regulation. Our findings provide new insights into the regulatory mechanism of acidic pH response in C. albicans.
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Affiliation(s)
- Guobo Guan
- Department of Infectious Diseases, Huashan Hospital, Shanghai Institute of Infectious Disease and Biosecurity and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Shuaihu Li
- Department of Infectious Diseases, Huashan Hospital, Shanghai Institute of Infectious Disease and Biosecurity and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Jian Bing
- Department of Infectious Diseases, Huashan Hospital, Shanghai Institute of Infectious Disease and Biosecurity and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
| | - Ling Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Li Tao
- Department of Infectious Diseases, Huashan Hospital, Shanghai Institute of Infectious Disease and Biosecurity and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, China
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Fenley JDC, de Barros PP, do Carmo PHF, Garcia MT, Rossoni RD, Junqueira JC. Repurposing HIV Protease Inhibitors Atazanavir and Darunavir as Antifungal Treatments against Candida albicans Infections: An In Vitro and In Vivo Study. Curr Issues Mol Biol 2022; 44:5379-5389. [PMID: 36354676 PMCID: PMC9688711 DOI: 10.3390/cimb44110364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/21/2022] [Accepted: 10/27/2022] [Indexed: 09/01/2023] Open
Abstract
Candida albicans is the chief etiological agent of candidiasis, a mycosis prevalent in individuals with acquired immunodeficiency syndrome (AIDS). In recent years, the introduction of human immunodeficiency virus (HIV) protease inhibitors (HIV-PI) has reduced the prevalence of candidiasis in these patients. Seeking new therapeutic strategies based on the perspective of drug repositioning, we evaluated the effects of two second-generation HIV-PIs, atazanavir (ATV) and darunavir (DRV), on virulence factors of C. albicans and experimental candidiasis. For this, clinical strains of C. albicans were subjected to in vitro and in vivo treatments with ATV or DRV. As a result, ATV and DRV exhibited antifungal activity against fungal cells at 512 μg/mL, reduced the viability and biomass of biofilms, and inhibited filamentation of C. albicans. In addition, these HIV-PIs downregulated the expression of SAP2 and BRC1 genes of C. albicans. In an in vivo study, prophylactic use of ATV and DRV prolonged the survival rate of Galleria mellonella larvae infected with C. albicans. Therefore, ATV and DRV showed activity against C. albicans by reducing cell growth, biofilm formation, filamentation, and expression of virulence genes. Furthermore, ATV and DRV decreased experimental candidiasis, suggesting the repurposing of HIV-PIs as antifungal treatments for C. albicans infections.
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Affiliation(s)
- Juliana de C. Fenley
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
| | - Patrícia P. de Barros
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
- Multicampi School of Medical Sciences, Federal University of Rio Grande do Norte (UFRN), Caicó, Rio Grande do Norte 59300-000, Brazil
| | - Paulo H. F. do Carmo
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
| | - Maíra T. Garcia
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
| | - Rodnei D. Rossoni
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
| | - Juliana C. Junqueira
- Department of Biosciences and Oral Diagnosis, Institute of Science and Technology, São Paulo State University (Unesp), São José dos Campos, São Paulo 12245-000, Brazil
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6
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Bettauer V, Costa ACBP, Omran RP, Massahi S, Kirbizakis E, Simpson S, Dumeaux V, Law C, Whiteway M, Hallett MT. A Deep Learning Approach to Capture the Essence of Candida albicans Morphologies. Microbiol Spectr 2022; 10:e0147222. [PMID: 35972285 PMCID: PMC9604015 DOI: 10.1128/spectrum.01472-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/25/2022] [Indexed: 12/31/2022] Open
Abstract
We present deep learning-based approaches for exploring the complex array of morphologies exhibited by the opportunistic human pathogen Candida albicans. Our system, entitled Candescence, automatically detects C. albicans cells from differential image contrast microscopy and labels each detected cell with one of nine morphologies. This ranges from yeast white and opaque forms to hyphal and pseudohyphal filamentous morphologies. The software is based upon a fully convolutional one-stage (FCOS) object detector, a deep learning technique that uses an extensive set of images that we manually annotated with the location and morphology of each cell. We developed a novel cumulative curriculum-based learning strategy that stratifies our images by difficulty from simple yeast forms to complex filamentous architectures. Candescence achieves very good performance (~85% recall; 81% precision) on this difficult learning set, where some images contain hundreds of cells with substantial intermixing between the predicted classes. To capture the essence of each C. albicans morphology and how they intermix, we used a second technique from deep learning entitled generative adversarial networks. The resultant models allow us to identify and explore technical variables, developmental trajectories, and morphological switches. Importantly, the model allows us to quantitatively capture morphological plasticity observed with genetically modified strains or strains grown in different media and environments. We envision Candescence as a community meeting point for quantitative explorations of C. albicans morphology. IMPORTANCE The fungus Candida albicans can "shape shift" between 12 morphologies in response to environmental variables. The cytoprotective capacity provided by this polymorphism makes C. albicans a formidable pathogen to treat clinically. Microscopy images of C. albicans colonies can contain hundreds of cells in different morphological states. Manual annotation of images can be difficult, especially as a result of densely packed and filamentous colonies and of technical artifacts from the microscopy itself. Manual annotation is inherently subjective, depending on the experience and opinion of annotators. Here, we built a deep learning approach entitled Candescence to parse images in an automated, quantitative, and objective fashion: each cell in an image is located and labeled with its morphology. Candescence effectively replaces simple rules based on visual phenotypes (size, shape, and shading) with neural circuitry capable of capturing subtle but salient features in images that may be too complex for human annotators.
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Affiliation(s)
- Van Bettauer
- Department of Computer Science and Software Engineering, Concordia University, Montreal, Quebec, Canada
| | | | | | - Samira Massahi
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | | | - Shawn Simpson
- Department of Computer Science and Software Engineering, Concordia University, Montreal, Quebec, Canada
| | - Vanessa Dumeaux
- Department of Anatomy and Cell Biology, Western University, London, Ontario, Canada
| | - Chris Law
- Centre for Microscopy and Cellular Imaging, Concordia University, Montreal, Quebec, Canada
| | - Malcolm Whiteway
- Department of Biology, Concordia University, Montreal, Quebec, Canada
| | - Michael T. Hallett
- Department of Biology, Concordia University, Montreal, Quebec, Canada
- Department of Biochemistry, Western University, London, Ontario, Canada
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7
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Phenotypic Switching and Filamentation in Candida haemulonii, an Emerging Opportunistic Pathogen of Humans. Microbiol Spectr 2021; 9:e0077921. [PMID: 34878301 PMCID: PMC8653834 DOI: 10.1128/spectrum.00779-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Phenotypic plasticity is a common strategy adopted by fungal pathogens to adapt to diverse host environments. Candida haemulonii is an emerging multidrug-resistant human pathogen that is closely related to Candida auris. Until recently, it was assumed that C. haemulonii is incapable of phenotypic switching or filamentous growth. In this study, we report the identification of three distinct phenotypes in C. haemulonii: white, pink, and filament. The white and pink phenotypes differ in cellular size, colony morphology, and coloration on phloxine B- or CuSO4-containing agar. Switching between the white and pink cell types is heritable and reversible and is referred to as “the primary switching system.” The additional switch phenotype, filament, has been identified and exhibits obviously filamentous morphology when grown on glycerol-containing medium. Several unique characteristics of the filamentous phenotype suggest that switching from or to this phenotype poses as a second yeast-filament switching system. The yeast-filament switch is nonheritable and temperature-dependent. Low temperatures favor the filamentous phenotype, whereas high temperatures promote filament-yeast transition. We further demonstrated that numerous aspects of the distinct cell types differ in numerous biological aspects, including their high temperature response, specific gene expression, CuSO4 tolerance, secreted aspartyl protease (SAP) activity, and virulence. Therefore, transition among the three phenotypes could enable C. haemulonii to rapidly adapt to, survive, and thrive in certain host niches, thereby contributing to its virulence. IMPORTANCE The capacity to switch between distinct cell types, known as phenotypic switching, is a common strategy adopted by Candida species to adapt to diverse environments. Despite considerable studies on phenotypic plasticity of various Candida species, Candida haemulonii is considered to be incapable of phenotypic switching or filamentous growth. Here, we report and describe filamentation and three distinct phenotypes (white, pink, and filament) in C. haemulonii. The three cell types differ in cellular and colony appearance, gene expression profiles, CuSO4 tolerance, and virulence. C. haemulonii cells switch heritably and reversibly between white and pink cell types, which is referred to as the “primary switching system.” Switching between pink and filamentous phenotypes is nonheritable and temperature-dependent, representing a second switching system. As in other Candida species, switching among distinct morphological types may provide C. haemulonii with phenotypic plasticity for rapid responses to the changing host environment, and may contribute to its virulence.
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8
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Ichikawa Y, Bruno VM, Woolford CA, Kim H, Do E, Brewer GC, Mitchell AP. Environmentally contingent control of Candida albicans cell wall integrity by transcriptional regulator Cup9. Genetics 2021; 218:iyab075. [PMID: 33989396 PMCID: PMC8864738 DOI: 10.1093/genetics/iyab075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 05/07/2021] [Indexed: 11/14/2022] Open
Abstract
The fungal pathogen Candida albicans is surrounded by a cell wall that is the target of caspofungin and other echinocandin antifungals. Candida albicans can grow in several morphological forms, notably budding yeast and hyphae. Yeast and hyphal forms differ in cell wall composition, leading us to hypothesize that there may be distinct genes required for yeast and hyphal responses to caspofungin. Mutants in 27 genes reported previously to be caspofungin hypersensitive under yeast growth conditions were all caspofungin hypersensitive under hyphal growth conditions as well. However, a screen of mutants defective in transcription factor genes revealed that Cup9 is required for normal caspofungin tolerance under hyphal and not yeast growth conditions. In a hyphal-defective efg1Δ/Δ background, Cup9 is still required for normal caspofungin tolerance. This result argues that Cup9 function is related to growth conditions rather than cell morphology. RNA-seq conducted under hyphal growth conditions indicated that 361 genes were up-regulated and 145 genes were down-regulated in response to caspofungin treatment. Both classes of caspofungin-responsive genes were enriched for cell wall-related proteins, as expected for a response to disruption of cell wall integrity and biosynthesis. The cup9Δ/Δ mutant, treated with caspofungin, had reduced RNA levels of 40 caspofungin up-regulated genes, and had increased RNA levels of 8 caspofungin down-regulated genes, an indication that Cup9 has a narrow rather than global role in the cell wall integrity response. Five Cup9-activated surface-protein genes have roles in cell wall integrity, based on mutant analysis published previously (PGA31 and IFF11) or shown here (ORF19.3499, ORF19.851, or PGA28), and therefore may explain the hypersensitivity of the cup9Δ/Δmutant to caspofungin. Our findings define Cup9 as a new determinant of caspofungin susceptibility.
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Affiliation(s)
- Yuichi Ichikawa
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Division of Cancer Biology, The Cancer Institute of JFCR, Koto-ku, Tokyo 135-8550, Japan
| | - Vincent M Bruno
- Department of Microbiology and Immunology and Institute of Genome Sciences, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Carol A Woolford
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - Hannah Kim
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA 19122, USA
| | - Eunsoo Do
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Grace C Brewer
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Aaron P Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
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9
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Wakade RS, Huang M, Mitchell AP, Wellington M, Krysan DJ. Intravital Imaging of Candida albicans Identifies Differential In Vitro and In Vivo Filamentation Phenotypes for Transcription Factor Deletion Mutants. mSphere 2021; 6:e0043621. [PMID: 34160243 PMCID: PMC8265662 DOI: 10.1128/msphere.00436-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 06/07/2021] [Indexed: 01/12/2023] Open
Abstract
Candida albicans is an important cause of human fungal infections. A widely studied virulence trait of C. albicans is its ability to undergo filamentation to hyphae and pseudohyphae. Although yeast, pseudohyphae, and hyphae are present in pathological samples of infected mammalian tissue, it has been challenging to characterize the role of regulatory networks and specific genes during in vivo filamentation. In addition, the phenotypic heterogeneity of C. albicans clinical isolates is becoming increasingly recognized, while correlating this heterogeneity with pathogenesis remains an important goal. Here, we describe the use of an intravital imaging approach to characterize C. albicans filamentation in a mammalian model of infection by taking advantage of the translucence of mouse pinna (ears). Using this model, we have found that the in vitro and in vivo filamentation phenotypes of different C. albicans isolates can vary significantly, particularly when in vivo filamentation is compared to solid agar-based assays. We also show that the well-characterized transcriptional regulators Efg1 and Brg1 appear to play important roles both in vivo and in vitro. In contrast, Ume6 is much more important in vitro than in vivo. Finally, strains that are dependent on Bcr1 for in vitro filamentation are able to form filaments in vivo in its absence. This intravital imaging approach provides a new approach to the systematic characterization of this important virulence trait during mammalian infection. Our initial studies provide support for the notion that the regulation and initiation of C. albicans filamentation in vivo is distinct from in vitro induction. IMPORTANCE Candida albicans is one of the most common causes of fungal infections in humans. C. albicans undergoes a transition from a round yeast form to a filamentous form during infection, which is critical for its ability to cause disease. Although this transition has been studied in the laboratory for years, methods to do so in an animal model of infection have been limited. We have developed a microscopy method to visualize fluorescently labeled C. albicans undergoing this transition in the subcutaneous tissue of mice. Our studies indicate that the regulation of C. albicans filamentation during infection is distinct from that observed in laboratory conditions.
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Affiliation(s)
- Rohan S. Wakade
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Manning Huang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Aaron P. Mitchell
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Melanie Wellington
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Damian J. Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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10
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Villa S, Hamideh M, Weinstock A, Qasim MN, Hazbun TR, Sellam A, Hernday AD, Thangamani S. Transcriptional control of hyphal morphogenesis in Candida albicans. FEMS Yeast Res 2021; 20:5715912. [PMID: 31981355 PMCID: PMC7000152 DOI: 10.1093/femsyr/foaa005] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 01/31/2020] [Indexed: 12/12/2022] Open
Abstract
Candida albicans is a multimorphic commensal organism and opportunistic fungal pathogen in humans. A morphological switch between unicellular budding yeast and multicellular filamentous hyphal growth forms plays a vital role in the virulence of C. albicans, and this transition is regulated in response to a range of environmental cues that are encountered in distinct host niches. Many unique transcription factors contribute to the transcriptional regulatory network that integrates these distinct environmental cues and determines which phenotypic state will be expressed. These hyphal morphogenesis regulators have been extensively investigated, and represent an increasingly important focus of study, due to their central role in controlling a key C. albicans virulence attribute. This review provides a succinct summary of the transcriptional regulatory factors and environmental signals that control hyphal morphogenesis in C. albicans.
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Affiliation(s)
- Sonia Villa
- Masters in Biomedical Science Program, Midwestern University, 19555 N. 59th Ave. Glendale, AZ 85308, USA
| | - Mohammad Hamideh
- Masters in Biomedical Science Program, Midwestern University, 19555 N. 59th Ave. Glendale, AZ 85308, USA
| | - Anthony Weinstock
- Arizona College of Osteopathic Medicine, Midwestern University, 19555 N. 59th Ave. Glendale, AZ 85308, USA
| | - Mohammad N Qasim
- Quantitative and Systems Biology Graduate Program, School of Natural Sciences, University of California, Merced, Merced, CA, 95343, USA
| | - Tony R Hazbun
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, West Lafayette, IN 47907, USA
| | - Adnane Sellam
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Université Laval, Quebec City, QC, Canada
| | - Aaron D Hernday
- Quantitative and Systems Biology Graduate Program, School of Natural Sciences, University of California, Merced, Merced, CA, 95343, USA.,Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, Merced, CA, 95343, USA
| | - Shankar Thangamani
- Department of Pathology and Population Medicine, College of Veterinary Medicine, Midwestern University, 19555 N. 59th Ave. Glendale, AZ 85308, USA
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11
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Rodríguez-Cerdeira C, Martínez-Herrera E, Carnero-Gregorio M, López-Barcenas A, Fabbrocini G, Fida M, El-Samahy M, González-Cespón JL. Pathogenesis and Clinical Relevance of Candida Biofilms in Vulvovaginal Candidiasis. Front Microbiol 2020; 11:544480. [PMID: 33262741 PMCID: PMC7686049 DOI: 10.3389/fmicb.2020.544480] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 10/23/2020] [Indexed: 12/30/2022] Open
Abstract
The ability of Candida spp. to form biofilms is crucial for its pathogenicity, and thus, it should be considered an important virulence factor in vulvovaginal candidiasis (VVC) and recurrent VVC (RVVC). Its ability to generate biofilms is multifactorial and is generally believed to depend on the site of infection, species and strain involved, and the microenvironment in which the infection develops. Therefore, both cell surface proteins, such as Hwp1, Als1, and Als2, and the cell wall-related protein, Sun41, play a critical role in the adhesion and virulence of the biofilm. Immunological and pharmacological approaches have identified the NLRP3 inflammasome as a crucial molecular factor contributing to host immunopathology. In this context, we have earlier shown that Candida albicans associated with hyphae-secreted aspartyl proteinases (specifically SAP4-6) contribute to the immunopathology of the disease. Transcriptome profiling has revealed that non-coding transcripts regulate protein synthesis post-transcriptionally, which is important for the growth of Candida spp. Other studies have employed RNA sequencing to identify differences in the 1,245 Candida genes involved in surface and invasive cellular metabolism regulation. In vitro systems allow the simultaneous processing of a large number of samples, making them an ideal screening technique for estimating various physicochemical parameters, testing the activity of antimicrobial agents, and analyzing genes involved in biofilm formation and regulation (in situ) in specific strains. Murine VVC models are used to study C. albicans infection, especially in trials of novel treatments and to understand the cause(s) for resistance to conventional therapeutics. This review on the clinical relevance of Candida biofilms in VVC focuses on important advances in its genomics, transcriptomics, and proteomics. Moreover, recent experiments on the influence of biofilm formation on VVC or RVVC pathogenesis in laboratory animals have been discussed. A clear elucidation of one of the pathogenesis mechanisms employed by Candida biofilms in vulvovaginal candidiasis and its applications in clinical practice represents the most significant contribution of this manuscript.
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Affiliation(s)
- Carmen Rodríguez-Cerdeira
- Efficiency, Quality, and Costs in Health Services Research Group (EFISALUD), Health Research Institute, SERGAS-UVIGO, Vigo, Spain.,Department of Dermatology, Hospital do Meixoeiro and University of Vigo, Vigo, Spain.,European Women's Dermatologic and Venereologic Society, Tui, Spain.,Psychodermatology Task Force of the Ibero-Latin American College of Dermatology (CILAD), Buenos Aires, Argentina
| | - Erick Martínez-Herrera
- Psychodermatology Task Force of the Ibero-Latin American College of Dermatology (CILAD), Buenos Aires, Argentina.,Unidad de Investigación, Hospital Regional de Alta Especialidad de Ixtapaluca, Ixtapaluca, Mexico
| | - Miguel Carnero-Gregorio
- Efficiency, Quality, and Costs in Health Services Research Group (EFISALUD), Health Research Institute, SERGAS-UVIGO, Vigo, Spain.,Department of Molecular Diagnosis (Array & NGS Division), Institute of Cellular and Molecular Studies, Lugo, Spain
| | - Adriana López-Barcenas
- European Women's Dermatologic and Venereologic Society, Tui, Spain.,Psychodermatology Task Force of the Ibero-Latin American College of Dermatology (CILAD), Buenos Aires, Argentina.,Section of Mycology, Department of Dermatology, Manuel Gea González hospital, Mexico City, Mexico
| | - Gabriella Fabbrocini
- European Women's Dermatologic and Venereologic Society, Tui, Spain.,Department of Dermatology, University of Naples Federico II, Naples, Italy
| | - Monika Fida
- European Women's Dermatologic and Venereologic Society, Tui, Spain.,Department of Dermatology, University of Medicine, Tirana, Tirana, Albania
| | - May El-Samahy
- European Women's Dermatologic and Venereologic Society, Tui, Spain.,Department of Dermatology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - José Luís González-Cespón
- Efficiency, Quality, and Costs in Health Services Research Group (EFISALUD), Health Research Institute, SERGAS-UVIGO, Vigo, Spain
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12
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Zhang Q, Xu L, Yuan S, Zhou Q, Wang X, Wang L, Hu Z, Yan Y. NGT1 Is Essential for N-Acetylglucosamine-Mediated Filamentous Growth Inhibition and HXK1 Functions as a Positive Regulator of Filamentous Growth in Candida tropicalis. Int J Mol Sci 2020; 21:ijms21114036. [PMID: 32516879 PMCID: PMC7312872 DOI: 10.3390/ijms21114036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 05/26/2020] [Accepted: 06/01/2020] [Indexed: 12/14/2022] Open
Abstract
Candida tropicalis is a pathogenic fungus that can cause opportunistic infections in humans. The ability of Candida species to transition between yeast and filamentous growth forms is essential to their ability to undergo environmental adaptation and to maintain virulence. In other fungal species, such as Candida albicans, N-acetylglucosamine (GlcNAc) can induce filamentous growth, whereas it suppresses such growth in C. tropicalis. In the present study, we found that knocking out the GlcNA-specific transporter gene NGT1 was sufficient to enhance C. tropicalis filamentous growth on Lee’s plus GlcNAc medium. This suggests that GlcNAc uptake into C. tropicalis cells is essential to the disruption of mycelial growth. As such, we further studied how GlcNAc catabolism-related genes were able to influence C. tropicalis filamentation. We found that HXK1 overexpression drove filamentous growth on Lee’s media containing glucose and GlcNAc, whereas the deletion of the same gene disrupted this filamentous growth. Interestingly, the deletion of the DAC1 or NAG1 genes impaired C. tropicalis growth on Lee’s plus GlcNAc plates. Overall, these results indicate that HXK1 can serve as a positive regulator of filamentous growth, with excess GlcNAc-6-PO4 accumulation being toxic to C. tropicalis. These findings may highlight novel therapeutic targets worthy of future investigation.
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The Als3 Cell Wall Adhesin Plays a Critical Role in Human Serum Amyloid A1-Induced Cell Death and Aggregation in Candida albicans. Antimicrob Agents Chemother 2020; 64:AAC.00024-20. [PMID: 32205353 DOI: 10.1128/aac.00024-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 03/16/2020] [Indexed: 01/22/2023] Open
Abstract
Antimicrobial peptides and proteins play critical roles in the host defense against invading pathogens. We recently discovered that recombinantly expressed human and mouse serum amyloid A1 (rhSAA1 and rmSAA1, respectively) proteins have potent antifungal activities against the major human fungal pathogen Candida albicans At high concentrations, rhSAA1 disrupts C. albicans membrane integrity and induces rapid fungal cell death. In the present study, we find that rhSAA1 promotes cell aggregation and targets the C. albicans cell wall adhesin Als3. Inactivation of ALS3 in C. albicans leads to a striking decrease in cell aggregation and cell death upon rhSAA1 treatment, suggesting that Als3 plays a critical role in SAA1 sensing. We further demonstrate that deletion of the transcriptional regulators controlling the expression of ALS3, such as AHR1, BCR1, and EFG1, in C. albicans results in similar effects to that of the als3/als3 mutant upon rhSAA1 treatment. Global gene expression profiling indicates that rhSAA1 has a discernible impact on the expression of cell wall- and metabolism-related genes, suggesting that rhSAA1 treatment could lead to a nutrient starvation effect on C. albicans cells.
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14
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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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Shafeeq S, Pannanusorn S, Elsharabasy Y, Ramírez-Zavala B, Morschhäuser J, Römling U. Impact of manganese on biofilm formation and cell morphology of Candida parapsilosis clinical isolates with different biofilm forming abilities. FEMS Yeast Res 2019; 19:5548773. [PMID: 31403663 PMCID: PMC6761954 DOI: 10.1093/femsyr/foz057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 08/09/2019] [Indexed: 12/20/2022] Open
Abstract
The commensal species Candida parapsilosis is an emerging human pathogen that has the ability to form biofilms. In this study, we explored the impact of the divalent cations cobalt (Co2+), copper (Cu2+), iron (Fe3+), manganese (Mn2+), nickel (Ni2+) and zinc (Zn2+) on biofilm formation of clinical isolates of C. parapsilosis with no, low and high biofilm forming abilities at 30 and 37°C. All strains besides one isolate showed a concentration-dependent enhancement of biofilm formation at 30°C in the presence of Mn2+ with a maximum at 2 mM. The biofilm forming ability of no and low biofilm forming isolates was >2-fold enhanced in the presence of 2 mM Mn2+, while the effect in high biofilm forming isolate was significantly less pronounced. Of note, cells in the biofilms of no and low biofilm forming strains differentiated into yeast and pseudohyphal cells similar in morphology to high biofilm formers. The biofilm transcriptional activator BCR1 has a dual developmental role in the absence and presence of 2 mM Mn2+ as it promoted biofilm formation of no biofilm forming strains, and, surprisingly, suppressed cells of no biofilm forming strains to develop into pseudohyphae and/or hyphae. Thus, environmental conditions can significantly affect the amount of biofilm formation and cell morphology of C. parapsilosis with Mn2+ to overcome developmental blocks to trigger biofilm formation and to partially relieve BCR1 suppressed cell differentiation.
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Affiliation(s)
- Sulman Shafeeq
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17165, Stockholm, Sweden
| | - Srisuda Pannanusorn
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17165, Stockholm, Sweden.,Department of Biotechnology, Faculty of Science and Technology, Thammasat University, 12120, Bangkok, Thailand
| | - Youssef Elsharabasy
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17165, Stockholm, Sweden
| | - Bernardo Ramírez-Zavala
- Institute for Molecular Infection Biology, University of Würzburg, D-97080, Würzburg, Germany
| | - Joachim Morschhäuser
- Institute for Molecular Infection Biology, University of Würzburg, D-97080, Würzburg, Germany
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17165, Stockholm, Sweden
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16
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Abstract
MAP kinases and their regulators are critical components of eukaryotic signaling pathways implicated in normal cell behavior as well as abnormal behaviors linked to diseases such as cancer. The mating pathway of the yeast Saccharomyces cerevisiae was central in establishing the MAP kinase paradigm. Here we investigate the mating pathway in a different ascomycete, the fungal pathogen C. albicans. In this dimorphic fungus MAP kinases are also implicated in the mating response, with two MAP kinases apparently playing redundant roles in the mating process. This work establishes that while some level of mating can occur in the presence of a single kinase, the Cek1 kinase is most important for mating, while the Cek2 kinase is involved in adaptation to signaling. While both kinases appear to be themselves regulated by dephosphorylation through the action of the Cpp1 phosphatase, this process appears important for mating only in the case of Cek1. We investigated the relationships of the Cek1 and Cek2 mitogen-activated protein (MAP) kinases and the putative MAP kinase phosphatase Cpp1 in the mating process of Candida albicans. Mutants of the CPP1 gene are hyperresponsive to pheromone, generating large halos, high levels of projections, and an increase in pheromone-responsive gene expression. Mating-type-homozygous opaque cells that lack both kinases are sterile, consistent with previous observations, although several lines of evidence show that the two kinases do not simply provide redundant functions in the mating process. Loss of CEK1 reduces mating significantly, to about 0.3% of wild-type strains, and also reduces projection formation and pheromone-mediated gene expression. In contrast, loss of CEK2 has less of an effect, reducing mating to approximately one-third that of the wild-type strain and moderately reducing projection formation but having little influence on the induction of gene expression. However, loss of Cek2 function reduces adaptation to pheromone-mediated arrest. The mutation enhances pheromone response halos to a level similar to that of cpp1 mutants, although the cpp1 mutants are considerably more mating defective than the cek2 mutant. The double cek2 cpp1 mutant shows enhanced responsiveness relative to either single mutant in terms of gene expression and halo formation, suggesting the kinase and phosphatase roles in the adaptation process are independent. Analysis of protein phosphorylation shows that Cek1 undergoes pheromone-mediated phosphorylation of the activation loop, and this phosphorylation is enhanced in cells lacking either the Cpp1 phosphatase or the Cek2 kinase. In addition, Cek1-GFP shows enhanced nuclear localization in response to pheromone treatment. In contrast, Cek2 shows no evidence for pheromone-mediated phosphorylation or pheromone-mediated nuclear localization. Intriguingly, however, deletion of CPP1 enhances both the phosphorylation state and the nuclear localization of Cek2-GFP. Overall, these results identify a complex interaction among the MAP kinases and MAP kinase phosphatase that function in the C. albicans mating pathway. IMPORTANCE MAP kinases and their regulators are critical components of eukaryotic signaling pathways implicated in normal cell behavior as well as abnormal behaviors linked to diseases such as cancer. The mating pathway of the yeast Saccharomyces cerevisiae was central in establishing the MAP kinase paradigm. Here we investigate the mating pathway in a different ascomycete, the fungal pathogen C. albicans. In this dimorphic fungus MAP kinases are also implicated in the mating response, with two MAP kinases apparently playing redundant roles in the mating process. This work establishes that while some level of mating can occur in the presence of a single kinase, the Cek1 kinase is most important for mating, while the Cek2 kinase is involved in adaptation to signaling. While both kinases appear to be themselves regulated by dephosphorylation through the action of the Cpp1 phosphatase, this process appears important for mating only in the case of Cek1.
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17
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Zheng Q, Zhang Q, Bing J, Ding X, Huang G. Environmental and genetic regulation of white-opaque switching inCandida tropicalis. Mol Microbiol 2017; 106:999-1017. [DOI: 10.1111/mmi.13862] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2017] [Indexed: 02/05/2023]
Affiliation(s)
- Qiushi Zheng
- State Key Laboratory of Mycology; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
- College of life sciences, University of Chinese Academy of Sciences; Beijing 100049 China
| | - Qiuyu Zhang
- State Key Laboratory of Mycology; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
- College of life sciences, University of Chinese Academy of Sciences; Beijing 100049 China
| | - Jian Bing
- State Key Laboratory of Mycology; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Xuefen Ding
- State Key Laboratory of Mycology; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
| | - Guanghua Huang
- State Key Laboratory of Mycology; Institute of Microbiology, Chinese Academy of Sciences; Beijing 100101 China
- College of life sciences, University of Chinese Academy of Sciences; Beijing 100049 China
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18
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Abstract
Candida albicans is an important etiological agent of superficial and life-threatening infections in individuals with compromised immune systems. To date, we know of several overlapping genetic networks that govern virulence attributes in this fungal pathogen. Classical use of deletion mutants has led to the discovery of numerous virulence factors over the years, and genome-wide functional analysis has propelled gene discovery at an even faster pace. Indeed, a number of recent studies using large-scale genetic screens followed by genome-wide functional analysis has allowed for the unbiased discovery of many new genes involved in C. albicans biology. Here we share our perspectives on the role of these studies in analyzing fundamental aspects of C. albicans virulence properties.
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Affiliation(s)
- Thabiso E Motaung
- a Agricultural Research Council - Small Grain Institute , Bethlehem , South Africa
| | - Ruan Ells
- b University of the Free Sate , Bloemfontein , South Africa
| | | | | | - Toi J Tsilo
- a Agricultural Research Council - Small Grain Institute , Bethlehem , South Africa.,c Department of Life and Consumer Sciences , University of South Africa , Pretoria , South Africa
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19
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Phenotypic Profiling Reveals that Candida albicans Opaque Cells Represent a Metabolically Specialized Cell State Compared to Default White Cells. mBio 2016; 7:mBio.01269-16. [PMID: 27879329 PMCID: PMC5120136 DOI: 10.1128/mbio.01269-16] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The white-opaque switch is a bistable, epigenetic transition affecting multiple traits in Candida albicans including mating, immunogenicity, and niche specificity. To compare how the two cell states respond to external cues, we examined the fitness, phenotypic switching, and filamentation properties of white cells and opaque cells under 1,440 different conditions at 25°C and 37°C. We demonstrate that white and opaque cells display striking differences in their integration of metabolic and thermal cues, so that the two states exhibit optimal fitness under distinct conditions. White cells were fitter than opaque cells under a wide range of environmental conditions, including growth at various pHs and in the presence of chemical stresses or antifungal drugs. This difference was exacerbated at 37°C, consistent with white cells being the default state of C. albicans in the mammalian host. In contrast, opaque cells showed greater fitness than white cells under select nutritional conditions, including growth on diverse peptides at 25°C. We further demonstrate that filamentation is significantly rewired between the two states, with white and opaque cells undergoing filamentous growth in response to distinct external cues. Genetic analysis was used to identify signaling pathways impacting the white-opaque transition both in vitro and in a murine model of commensal colonization, and three sugar sensing pathways are revealed as regulators of the switch. Together, these findings establish that white and opaque cells are programmed for differential integration of metabolic and thermal cues and that opaque cells represent a more metabolically specialized cell state than the default white state. IMPORTANCE Epigenetic transitions are an important mechanism by which microbes adapt to external stimuli. For Candida albicans, such transitions are crucial for adaptation to complex, fluctuating environments, and therefore contribute to its success as a human pathogen. The white-opaque switch modulates multiple C. albicans attributes, from sexual competency to niche specificity. Here, we demonstrate that metabolic circuits are extensively rewired between white and opaque states, so that the two cell types exhibit optimal fitness under different nutritional conditions and at different temperatures. We thereby establish that epigenetic events can profoundly alter the metabolism of fungal cells. We also demonstrate that epigenetic switching regulates filamentation and biofilm formation, two phenotypes closely associated with pathogenesis. These experiments reveal that white cells, considered the most clinically relevant form of C. albicans, are a "general-purpose" state suited to many environments, whereas opaque cells appear to represent a more metabolically specialized form of the species.
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20
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Noble SM, Gianetti BA, Witchley JN. Candida albicans cell-type switching and functional plasticity in the mammalian host. Nat Rev Microbiol 2016; 15:96-108. [PMID: 27867199 DOI: 10.1038/nrmicro.2016.157] [Citation(s) in RCA: 330] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Candida albicans is a ubiquitous commensal of the mammalian microbiome and the most prevalent fungal pathogen of humans. A cell-type transition between yeast and hyphal morphologies in C. albicans was thought to underlie much of the variation in virulence observed in different host tissues. However, novel yeast-like cell morphotypes, including opaque(a/α), grey and gastrointestinally induced transition (GUT) cell types, were recently reported that exhibit marked differences in vitro and in animal models of commensalism and disease. In this Review, we explore the characteristics of the classic cell types - yeast, hyphae, pseudohyphae and chlamydospores - as well as the newly identified yeast-like morphotypes. We highlight emerging knowledge about the associations of these different morphotypes with different host niches and virulence potential, as well as the environmental cues and signalling pathways that are involved in the morphological transitions.
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Affiliation(s)
- Suzanne M Noble
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine.,Infectious Diseases Division, Department of Medicine, University of California San Francisco (UCSF) School of Medicine, San Francisco, California 94143, USA
| | - Brittany A Gianetti
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine
| | - Jessica N Witchley
- Department of Microbiology and Immunology, University of California San Francisco (UCSF) School of Medicine
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21
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Liang W, Guan G, Dai Y, Cao C, Tao L, Du H, Nobile CJ, Zhong J, Huang G. Lactic acid bacteria differentially regulate filamentation in two heritable cell types of the human fungal pathogen Candida albicans. Mol Microbiol 2016; 102:506-519. [PMID: 27479705 DOI: 10.1111/mmi.13475] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2016] [Indexed: 01/17/2023]
Abstract
Microorganisms rarely exist as single species in natural environments. The opportunistic fungal pathogen Candida albicans and lactic acid bacteria (LAB) are common members of the microbiota of several human niches such as the mouth, gut and vagina. Lactic acid bacteria are known to suppress filamentation, a key virulence feature of C. albicans, through the production of lactic acid and other metabolites. Here we report that C. albicans cells switch between two heritable cell types, white and opaque, to undergo filamentation to adapt to diversified environments. We show that acidic pH conditions caused by LAB and low temperatures support opaque cell filamentation, while neutral pH conditions and high temperatures promote white cell filamentation. The cAMP signalling pathway and the Rfg1 transcription factor play major roles in regulating the responses to these conditions. This cell type-specific response of C. albicans to different environmental conditions reflects its elaborate regulatory control of phenotypic plasticity.
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Affiliation(s)
- Weihong Liang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Guobo Guan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yu Dai
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Chengjun Cao
- 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 Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Han Du
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Clarissa J Nobile
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, 5200 N. Lake Road, Merced, California, United States of America
| | - Jin Zhong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Guanghua Huang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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22
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Xu N, Dong YJ, Yu QL, Zhang B, Zhang M, Jia C, Chen YL, Zhang B, Xing LJ, Li MC. Convergent Regulation of Candida albicans Aft2 and Czf1 in Invasive and Opaque Filamentation. J Cell Biochem 2016; 116:1908-18. [PMID: 25716417 DOI: 10.1002/jcb.25146] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 02/20/2015] [Indexed: 12/18/2022]
Abstract
Candida albicans is the most common fungal pathogen of mucosal infections and invasive diseases in immuno-compromised humans. The abilities of yeast-hyphal growth and white-opaque switching affect C. albicans physiology and virulence. Here, we showed that C. albicans Aft2 regulator was required for embedded filamentous growth and opaque cell-type formation. Under low-temperature matrix embedded conditions, Aft2 functioned downstream of Czf1-mediated pathway and was required for invasive filamentation. Moreover, deletion of AFT2 significantly reduced opaque cell-type formation under N-acetylglucosamine (GlcNAc) inducing conditions. Ectopic expression of CZF1 slightly increased the white-opaque switching frequency in the aft2Δ/Δ mutant, but did not completely restore to wild-type levels, suggesting that Czf1 at least partially bypassed the essential requirement for Aft2 in response to opaque-inducing cues. In addition, multiple environmental cues altered AFT2 mRNA and protein levels, such as low temperature, physical environment and GlcNAc. Although the absence of Czf1 or Efg1 also increased the expression level of AFT2 gene, deletion of CZF1 remarkably reduced the stability of Aft2 protein. Furthermore, C. albicans Aft2 physically interacted with Czf1 under all tested conditions, whereas the interaction between Aft2 and Efg1 was barely detectable under embedded conditions, supporting the hypothesis that Aft2, together with Czf1, contributed to activate filamentous growth by antagonizing Efg1-mediated repression under matrix-embedded conditions.
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Affiliation(s)
- Ning Xu
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.,Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China
| | - Yi-Jie Dong
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Qi-Lin Yu
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Bing Zhang
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Meng Zhang
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Chang Jia
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yu-Lu Chen
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Biao Zhang
- Tianjin University of Traditional Chinese Medicine, Tianjin, 300193, China
| | - Lai-Jun Xing
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Ming-Chun Li
- Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
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Wang Y. Hgc1-Cdc28-how much does a single protein kinase do in the regulation of hyphal development in Candida albicans? J Microbiol 2016; 54:170-7. [PMID: 26920877 DOI: 10.1007/s12275-016-5550-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 12/03/2015] [Accepted: 12/03/2015] [Indexed: 01/06/2023]
Abstract
The fungal human pathogen Candida albicans can cause invasive infection with high mortality rates. A key virulence factor is its ability to switch between three morphologies: yeast, pseudohyphae and hyphae. In contrast to the ovalshaped unicellular yeast cells, hyphae are highly elongated, tube-like, and multicellular. A long-standing question is what coordinates all the cellular machines to construct cells with distinct shapes. Hyphal-specific genes (HSGs) are thought to hold the answer. Among the numerous HSGs found, only UME6 and HGC1 are required for hyphal development. UME6 encodes a transcription factor that regulates many HSGs including HGC1. HGC1 encodes a G1 cyclin which partners with the Cdc28 cyclin-dependent kinase. Hgc1-Cdc28 simultaneously phosphorylates and regulates multiple substrates, thus controlling multiple cellular apparatuses for morphogenesis. This review is focused on major progresses made in the past decade on Hgc1's roles and regulation in C. albicans hyphal development and other traits important for infection.
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Affiliation(s)
- Yue Wang
- Candida albicans Biology Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology, and Research, and Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
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24
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Zhang Q, Tao L, Guan G, Yue H, Liang W, Cao C, Dai Y, Huang G. Regulation of filamentation in the human fungal pathogenCandida tropicalis. Mol Microbiol 2015; 99:528-45. [DOI: 10.1111/mmi.13247] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2015] [Indexed: 12/14/2022]
Affiliation(s)
- Qiuyu Zhang
- 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 Mycology; Institute of Microbiology; Chinese Academy of Sciences; Beijing China
| | - Guobo Guan
- State Key Laboratory of Mycology; Institute of Microbiology; Chinese Academy of Sciences; Beijing 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
| | - Chengjun Cao
- State Key Laboratory of Mycology; Institute of Microbiology; Chinese Academy of Sciences; Beijing China
- University of Chinese Academy of Sciences; Beijing China
| | - Yu Dai
- State Key Laboratory of Mycology; Institute of Microbiology; Chinese Academy of Sciences; Beijing China
| | - Guanghua Huang
- State Key Laboratory of Mycology; Institute of Microbiology; Chinese Academy of Sciences; Beijing China
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25
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Functional Divergence of Hsp90 Genetic Interactions in Biofilm and Planktonic Cellular States. PLoS One 2015; 10:e0137947. [PMID: 26367740 PMCID: PMC4569550 DOI: 10.1371/journal.pone.0137947] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/24/2015] [Indexed: 01/23/2023] Open
Abstract
Candida albicans is among the most prevalent opportunistic fungal pathogens. Its capacity to cause life-threatening bloodstream infections is associated with the ability to form biofilms, which are intrinsically drug resistant reservoirs for dispersal. A key regulator of biofilm drug resistance and dispersal is the molecular chaperone Hsp90, which stabilizes many signal transducers. We previously identified 226 C. albicans Hsp90 genetic interactors under planktonic conditions, of which 56 are involved in transcriptional regulation. Six of these transcriptional regulators have previously been implicated in biofilm formation, suggesting that Hsp90 genetic interactions identified in planktonic conditions may have functional significance in biofilms. Here, we explored the relationship between Hsp90 and five of these transcription factor genetic interactors: BCR1, MIG1, TEC1, TUP1, and UPC2. We deleted each transcription factor gene in an Hsp90 conditional expression strain, and assessed biofilm formation and morphogenesis. Strikingly, depletion of Hsp90 conferred no additional biofilm defect in the mutants. An interaction was observed in which deletion of BCR1 enhanced filamentation upon reduction of Hsp90 levels. Further, although Hsp90 modulates expression of TEC1, TUP1, and UPC2 in planktonic conditions, it has no impact in biofilms. Lastly, we probed for physical interactions between Hsp90 and Tup1, whose WD40 domain suggests that it might interact with Hsp90 directly. Hsp90 and Tup1 formed a stable complex, independent of temperature or developmental state. Our results illuminate a physical interaction between Hsp90 and a key transcriptional regulator of filamentation and biofilm formation, and suggest that Hsp90 has distinct genetic interactions in planktonic and biofilm cellular states.
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26
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Desai PR, van Wijlick L, Kurtz D, Juchimiuk M, Ernst JF. Hypoxia and Temperature Regulated Morphogenesis in Candida albicans. PLoS Genet 2015; 11:e1005447. [PMID: 26274602 PMCID: PMC4537295 DOI: 10.1371/journal.pgen.1005447] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Accepted: 07/15/2015] [Indexed: 01/31/2023] Open
Abstract
Candida albicans is a common commensal in the human gut but in predisposed patients it can become an important human fungal pathogen. As a commensal, C. albicans adapts to low-oxygen conditions and represses its hyphal development by the transcription factor Efg1, which under normoxia activates filamentation. The repressive hypoxic but not the normoxic function of Efg1 required its unmodified N-terminus, was prevented by phosphomimetic residues at normoxic phosphorylation sites T179 and T206 and occurred only at temperatures ≤35°C. Genome-wide binding sites for native Efg1 identified 300 hypoxia-specific target genes, which overlapped partially with hypoxic binding sites for Ace2, a known positive regulator of hypoxic filamentation. Transcriptional analyses revealed that EFG1, ACE2 and their identified targets BCR1 and BRG1 encode an interconnected regulatory hub, in which Efg1/Bcr1 act as negative and Ace2/Brg1 act as positive regulators of gene expression under hypoxia. In this circuit, the hypoxic function of Ace2 was stimulated by elevated CO2 levels. The hyperfilamentous phenotype of efg1 and bcr1 mutants depended on Ace2/Brg1 regulators and required increased expression of genes encoding Cek1 MAP kinase and its downstream target Cph1. The intricate temperature-dependent regulatory mechanisms under hypoxia suggest that C. albicans restricts hyphal morphogenesis in oxygen-poor body niches, possibly to persist as a commensal in the human host.
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Affiliation(s)
- Prashant R. Desai
- Department Biologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Lasse van Wijlick
- Department Biologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany
- Manchot Graduate School Molecules of Infection, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Dagmar Kurtz
- Department Biologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Mateusz Juchimiuk
- Department Biologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany
| | - Joachim F. Ernst
- Department Biologie, Molekulare Mykologie, Heinrich-Heine-Universität, Düsseldorf, Germany
- Manchot Graduate School Molecules of Infection, Heinrich-Heine-Universität, Düsseldorf, Germany
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27
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Du H, Li X, Huang G, Kang Y, Zhu L. The zinc-finger transcription factor, Ofi1, regulates white-opaque switching and filamentation in the yeast Candida albicans. Acta Biochim Biophys Sin (Shanghai) 2015; 47:335-41. [PMID: 25757952 DOI: 10.1093/abbs/gmv011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 01/06/2015] [Indexed: 11/14/2022] Open
Abstract
Candida albicans is a major fungal pathogen of humans. The most striking biological feature of C. albicans is its phenotypic plasticity, allowing it to undergo morphological transitions in response to various environmental cues. Transcription factors play critical roles in the regulation of morphological transitions. Here, we report the role of opaque and filamentation inducer 1 (Ofi1), a previously uncharacterized zinc-finger-containing protein encoded by the gene orf19.4972, in the regulation of white-opaque switching and filamentous growth. Over-expression of OFI1 not only induced white-to-opaque switching but also promoted filamentation and invasive growth in C. albicans. Deletion of OFI1 had no obvious effect on filamentation under the culture conditions tested, while deletion of OFI1 reduced the frequency of white-to-opaque switching. We propose that Ofi1 functions downstream of Wor1, the master regulator of white-opaque switching. However, over-expression of OFI1 in the wor1/wor1 mutant could not induce the opaque phenotype, suggesting that Ofi1 does not work alone and other transcription factors downstream of Wor1 are also involved in this regulation. Given the importance of Ofi1 in the regulation of white-opaque switching and filamentation, the present study establishes a new link between these two processes.
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Affiliation(s)
- Han Du
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
| | - Xiaoling Li
- Department of Microbiology, Guiyang Medical University, Guiyang 550004, China
| | - Guanghua Huang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yingqian Kang
- Department of Microbiology, Guiyang Medical University, Guiyang 550004, China
| | - Liquan Zhu
- College of Agronomy and Biotechnology, Southwest University, Chongqing 400715, China
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28
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Abstract
Only few Candida species, e.g., Candida albicans, Candida glabrata, Candida dubliniensis, and Candida parapsilosis, are successful colonizers of a human host. Under certain circumstances these species can cause infections ranging from superficial to life-threatening disseminated candidiasis. The success of C. albicans, the most prevalent and best studied Candida species, as both commensal and human pathogen depends on its genetic, biochemical, and morphological flexibility which facilitates adaptation to a wide range of host niches. In addition, formation of biofilms provides additional protection from adverse environmental conditions. Furthermore, in many host niches Candida cells coexist with members of the human microbiome. The resulting fungal-bacterial interactions have a major influence on the success of C. albicans as commensal and also influence disease development and outcome. In this chapter, we review the current knowledge of important survival strategies of Candida spp., focusing on fundamental fitness and virulence traits of C. albicans.
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Affiliation(s)
- Melanie Polke
- Research Group Microbial Immunology, Hans-Knoell-Institute, Jena, Germany; Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany
| | - Bernhard Hube
- Department Microbial Pathogenicity Mechanisms, Hans-Knoell-Institute, Jena, Germany; Friedrich-Schiller-University, Jena, Germany; Center for Sepsis Control and Care, Jena University Hospital, Jena, Germany
| | - Ilse D Jacobsen
- Research Group Microbial Immunology, Hans-Knoell-Institute, Jena, Germany; Friedrich-Schiller-University, Jena, Germany
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29
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Tao L, Du H, Guan G, Dai Y, Nobile CJ, Liang W, Cao C, Zhang Q, Zhong J, Huang G. Discovery of a "white-gray-opaque" tristable phenotypic switching system in candida albicans: roles of non-genetic diversity in host adaptation. PLoS Biol 2014; 12:e1001830. [PMID: 24691005 PMCID: PMC3972085 DOI: 10.1371/journal.pbio.1001830] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/21/2014] [Indexed: 11/19/2022] Open
Abstract
This study describes a novel “white-gray-opaque” tristable phenotypic switching system in the human fungal pathogen Candida albicans, revealing additional complexity in this organism's ability to adapt to changing environments. Non-genetic phenotypic variations play a critical role in the adaption to environmental changes in microbial organisms. Candida albicans, a major human fungal pathogen, can switch between several morphological phenotypes. This ability is critical for its commensal lifestyle and for its ability to cause infections. Here, we report the discovery of a novel morphological form in C. albicans, referred to as the “gray” phenotype, which forms a tristable phenotypic switching system with the previously reported white and opaque phenotypes. White, gray, and opaque cell types differ in a number of aspects including cellular and colony appearances, mating competency, secreted aspartyl proteinase (Sap) activities, and virulence. Of the three cell types, gray cells exhibit the highest Sap activity and the highest ability to cause cutaneous infections. The three phenotypes form a tristable phenotypic switching system, which is independent of the regulation of the mating type locus (MTL). Gray cells mate over 1,000 times more efficiently than do white cells, but less efficiently than do opaque cells. We further demonstrate that the master regulator of white-opaque switching, Wor1, is essential for opaque cell formation, but is not required for white-gray transitions. The Efg1 regulator is required for maintenance of the white phenotype, but is not required for gray-opaque transitions. Interestingly, the wor1/wor1 efg1/efg1 double mutant is locked in the gray phenotype, suggesting that Wor1 and Efg1 could function coordinately and play a central role in the regulation of gray cell formation. Global transcriptional analysis indicates that white, gray, and opaque cells exhibit distinct gene expression profiles, which partly explain their differences in causing infections, adaptation ability to diverse host niches, metabolic profiles, and stress responses. Therefore, the white-gray-opaque tristable phenotypic switching system in C. albicans may play a significant role in a wide range of biological aspects in this common commensal and pathogenic fungus. The capacity of the yeast Candida albicans to grow in several cellular forms—a phenomenon known as phenotypic plasticity—is critical for its survival and for its ability to thrive and cause infection in the human host. In this study, we report a novel form of C. albicans, the “gray” phenotype, which may enhance fitness and confer an adaptive advantage for this important pathogenic yeast in certain host environments. The gray cell type, together with the previously discovered “white” and “opaque” cell types, forms a tristable phenotypic switching system. The three phenotypes differ in their cellular and colony appearance, their global transcriptional profiles, their production of secreted aspartyl proteinases (enzymes that degrade host tissues and release nutrients), and their virulence in different infection models. Moreover, gray cells exhibit a level of mating competency that is intermediate between that of white and opaque cells. We further demonstrate that two key transcriptional regulators, Wor1 and Efg1, play central roles in the regulation of the “white-gray-opaque” tristable transitions. Our study reveals a multi-stable and heritable switching system, indicating that the adoption of distinct morphological forms in response to environmental change could be much more elaborate than previously thought.
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Affiliation(s)
- Li Tao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Han Du
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Guobo Guan
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yu Dai
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Clarissa J. Nobile
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, Merced, California, United States of America
| | - Weihong Liang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chengjun Cao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qiuyu Zhang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jin Zhong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Guanghua Huang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- * E-mail:
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30
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Quorum sensing controls hyphal initiation in Candida albicans through Ubr1-mediated protein degradation. Proc Natl Acad Sci U S A 2014; 111:1975-80. [PMID: 24449897 DOI: 10.1073/pnas.1318690111] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Candida albicans is the most common cause of invasive fungal infections in humans. Its ability to undergo the morphological transition from yeast to hyphal growth forms is critical for its pathogenesis. Hyphal initiation requires the activation of the cAMP-PKA pathway, which down-regulates the expression of NRG1, the major repressor of hyphal development. Hyphal initiation also requires inoculation of a small amount of C. albicans cells from overnight culture to fresh medium. This inoculation releases the inhibition from farnesol, a quorum-sensing molecule of C. albicans, that accumulated in the spent medium. Here, we show that farnesol inhibits hyphal initiation mainly through blocking the protein degradation of Nrg1. Through screening a kinase mutant library, we identified Sok1 as the kinase required for Nrg1 degradation during inoculation. SOK1 expression is transiently activated on inoculation during hyphal initiation, and overexpression of SOK1 overcomes the farnesol-mediated inhibition of hyphal initiation. Screening a collection of transcription factor mutants, the homeodomain-containing transcription repressor Cup9 is found to be responsible for the repression of SOK1 expression in response to farnesol inhibition. Interestingly, farnesol inhibits Cup9 degradation mediated by the N-end rule E3 ubiquitin ligase, Ubr1. Therefore, hyphal initiation requires both the cAMP-PKA pathway-dependent transcriptional down-regulation of NRG1 and Sok1-mediated degradation of Nrg1 protein. The latter is triggered by the release from farnesol inhibition of Cup9 degradation and consequently, derepression of SOK1 transcription. Neither pathway alone is sufficient for hyphal initiation.
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31
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Affiliation(s)
- David Kadosh
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
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32
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Characterization of biofilm formation and the role of BCR1 in clinical isolates of Candida parapsilosis. EUKARYOTIC CELL 2013; 13:438-51. [PMID: 24297446 DOI: 10.1128/ec.00181-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In Candida parapsilosis, biofilm formation is considered to be a major virulence factor. Previously, we determined the ability of 33 clinical isolates causing bloodstream infection to form biofilms and identified three distinct groups of biofilm-forming strains (negative, low, and high). Here, we establish two different biofilm structures among strains forming large amounts of biofilm in which strains with complex spider-like structures formed robust biofilms on different surface materials with increased resistance to fluconazole. Surprisingly, the transcription factor Bcr1, required for biofilm formation in Candida albicans and C. parapsilosis, has an essential role only in strains with low capacity for biofilm formation. Although BCR1 leads to the formation of more and longer pseudohyphae, it was not required for initial adhesion and formation of mature biofilms in strains with a high level of biofilm formation. Furthermore, an additional phenotype affected by BCR1 was the switch in colony morphology from rough to crepe, but only in strains forming high levels of biofilm. All bcr1Δ/Δ mutants showed increased proteolytic activity and increased susceptibility to the antimicrobial peptides protamine and RP-1 compared to corresponding wild-type and complemented strains. Taken together, our results demonstrate that biofilm formation in clinical isolates of C. parapsilosis is both dependent and independent of BCR1, but even in strains which showed a BCR1-independent biofilm phenotype, BCR1 has alternative physiological functions.
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