1
|
Kim MJ, Cravener M, Solis N, Filler SG, Mitchell AP. A Brg1-Rme1 circuit in Candida albicans hyphal gene regulation. mBio 2024; 15:e0187224. [PMID: 39078139 PMCID: PMC11389389 DOI: 10.1128/mbio.01872-24] [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: 06/18/2024] [Accepted: 06/28/2024] [Indexed: 07/31/2024] Open
Abstract
Major Candida albicans virulence traits include its ability to make hyphae, to produce a biofilm, and to damage host cells. These traits depend upon expression of hypha-associated genes. A gene expression comparison among clinical isolates suggested that transcription factor Rme1, established by previous studies to be a positive regulator of chlamydospore formation, may also be a negative regulator of hypha-associated genes. Engineered RME1 overexpression supported this hypothesis, but no relevant rme1Δ/Δ mutant phenotype was detected. We reasoned that Rme1 may function within a specific regulatory pathway. This idea was supported by our finding that an rme1Δ/Δ mutation relieves the need for biofilm regulator Brg1 in biofilm formation. The impact of the rme1Δ/Δ mutation is most prominent under static or "biofilm-like" growth conditions. RNA sequencing (RNA-seq) of cells grown under biofilm-like conditions indicates that Brg1 activates hypha-associated genes indirectly via repression of RME1: hypha-associated gene expression levels are substantially reduced in a brg1Δ/Δ mutant and partially restored in a brg1Δ/Δ rme1Δ/Δ double mutant. An rme1Δ/Δ mutation does not simply bypass Brg1, because iron homeostasis genes depend upon Brg1 regardless of Rme1. Rme1 thus connects Brg1 to the targets relevant to hypha and biofilm formation under biofilm growth conditions.IMPORTANCECandida albicans is a major fungal pathogen of humans, and its ability to grow as a surface-associated biofilm on implanted devices is a common cause of infection. Here, we describe a new regulator of biofilm formation, RME1, whose activity is most prominent under biofilm-like growth conditions.
Collapse
Affiliation(s)
- Min-Ju Kim
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Max Cravener
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Norma Solis
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Scott G Filler
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Aaron P Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| |
Collapse
|
2
|
Anderson MZ, Dietz SM. Evolution and strain diversity advance exploration of Candida albicans biology. mSphere 2024; 9:e0064123. [PMID: 39012122 PMCID: PMC11351040 DOI: 10.1128/msphere.00641-23] [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] [Indexed: 07/17/2024] Open
Abstract
Fungi were some of the earliest organismal systems used to explore mutational processes and its phenotypic consequences on members of a species. Yeasts that cause significant human disease were quickly incorporated into these investigations to define the genetic and phenotypic drivers of virulence. Among Candida species, Candida albicans has emerged as a model for studying genomic processes of evolution because of its clinical relevance, relatively small genome, and ability to tolerate complex chromosomal changes. Here, we describe major recent findings that used evolution of strains from defined genetic backgrounds to delineate mutational and adaptative processes and include how nascent exploration into naturally occurring variation is contributing to these conceptual frameworks. Ultimately, efforts to discern adaptive mechanisms used by C. albicans will continue to divulge new biology and can better inform treatment regimens for the increasing prevalence of fungal disease.
Collapse
Affiliation(s)
- Matthew Z. Anderson
- Department of Medical Genetics, Laboratory of Genetics, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Center for Genomic Science Innovation, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Siobhan M. Dietz
- Cellular and Molecular Pathology Graduate Program, University of Wisconsin—Madison, Madison, Wisconsin, USA
| |
Collapse
|
3
|
Lindemann-Perez E, Perez JC. Candida albicans natural diversity: a resource to dissect fungal commensalism and pathogenesis. Curr Opin Microbiol 2024; 80:102493. [PMID: 38833793 DOI: 10.1016/j.mib.2024.102493] [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: 03/26/2024] [Revised: 05/02/2024] [Accepted: 05/22/2024] [Indexed: 06/06/2024]
Abstract
Candida albicans is a ubiquitous fungus of humans. It is not only a component of the oral and intestinal microbiota of most healthy adults but also a major cause of mucosal disorders and life-threatening disseminated infections. Until recently, research on the biology and pathogenesis of the fungus was largely based on a single clinical isolate. We review investigations that have started to dissect a diverse set of C. albicans strains. Using different approaches to leverage the species' phenotypic and/or genetic diversity, these studies illuminate the wide range of interactions between fungus and host. While connecting genetic variants to phenotypes of interest remains challenging, research on C. albicans' natural diversity is central to understand fungal commensalism and pathogenesis.
Collapse
Affiliation(s)
- Elena Lindemann-Perez
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, USA
| | - J Christian Perez
- Department of Microbiology and Molecular Genetics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, USA.
| |
Collapse
|
4
|
Xiong L, Goerlich K, Do E, Mitchell AP. Strain variation in the Candida albicans iron limitation response. mSphere 2024; 9:e0037224. [PMID: 38980069 PMCID: PMC11288005 DOI: 10.1128/msphere.00372-24] [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: 05/03/2024] [Accepted: 06/16/2024] [Indexed: 07/10/2024] Open
Abstract
Iron acquisition is critical for pathogens to proliferate during invasive infection, and the human fungal pathogen Candida albicans is no exception. The iron regulatory network, established in reference strain SC5314 and derivatives, includes the central player Sef1, a transcription factor that activates iron acquisition genes in response to iron limitation. Here, we explored potential variation in this network among five diverse C. albicans strains through mutant analysis, Nanostring gene expression profiling, and, for two strains, RNA-Seq. Our findings highlight four features that may inform future studies of natural variation and iron acquisition in this species. (i) Conformity: In all strains, major iron acquisition genes are upregulated during iron limitation, and a sef1Δ/Δ mutation impairs that response and growth during iron limitation. (ii) Response variation: Some aspects of the iron limitation response vary among strains, notably the activation of hypha-associated genes. As this gene set is tied to tissue damage and virulence, variation may impact the progression of infection. (iii) Genotype-phenotype variation: The impact of a sef1Δ/Δ mutation on cell wall integrity varies, and for the two strains examined the phenotype correlated with sef1Δ/Δ impact on several cell wall integrity genes. (iv) Phenotype discovery: DNA repair genes were induced modestly by iron limitation in sef1Δ/Δ mutants, with fold changes we would usually ignore. However, the response occurred in both strains tested and was reminiscent of a much stronger response described in Cryptococcus neoformans, a suggestion that it may have biological meaning. In fact, we observed that the iron limitation of a sef1Δ/Δ mutant caused recessive phenotypes to emerge at two heterozygous loci. Overall, our results show that a network that is critical for pathogen proliferation presents variation outside of its core functions.IMPORTANCEA key virulence factor of Candida albicans is the ability to maintain iron homeostasis in the host where iron is scarce. We focused on a central iron regulator, SEF1. We found that iron regulator Sef1 is required for growth, cell wall integrity, and genome integrity during iron limitation. The novel aspect of this work is the characterization of strain variation in a circuit that is required for survival in the host and the connection of iron acquisition to genome integrity in C. albicans.
Collapse
Affiliation(s)
- Liping Xiong
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | | | - Eunsoo Do
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| |
Collapse
|
5
|
Tseng KY, Huang YT, Huang YT, Su YT, Wang AN, Weng WY, Ke CL, Yeh YC, Wang JJ, Du SH, Gu ZQ, Chen WL, Lin CH, Tsai YH. Regulation of candidalysin underlies Candida albicans persistence in intravascular catheters by modulating NETosis. PLoS Pathog 2024; 20:e1012319. [PMID: 38885290 PMCID: PMC11213320 DOI: 10.1371/journal.ppat.1012319] [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: 01/12/2024] [Revised: 06/28/2024] [Accepted: 06/06/2024] [Indexed: 06/20/2024] Open
Abstract
Candida albicans is a leading cause of intravascular catheter-related infections. The capacity for biofilm formation has been proposed to contribute to the persistence of this fungal pathogen on catheter surfaces. While efforts have been devoted to identifying microbial factors that modulate C. albicans biofilm formation in vitro, our understanding of the host factors that may shape C. albicans persistence in intravascular catheters is lacking. Here, we used multiphoton microscopy to characterize biofilms in intravascular catheters removed from candidiasis patients. We demonstrated that, NETosis, a type of neutrophil cell death with antimicrobial activity, was implicated in the interaction of immune cells with C. albicans in the catheters. The catheter isolates exhibited reduced filamentation and candidalysin gene expression, specifically in the total parenteral nutrition culture environment. Furthermore, we showed that the ablation of candidalysin expression in C. albicans reduced NETosis and conferred resistance to neutrophil-mediated fungal biofilm elimination. Our findings illustrate the role of neutrophil NETosis in modulating C. albicans biofilm persistence in an intravascular catheter, highlighting that C. albicans can benefit from reduced virulence expression to promote its persistence in an intravascular catheter.
Collapse
Affiliation(s)
- Kuo-Yao Tseng
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yu-Tsung Huang
- Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
- Graduate Institute of Clinical Laboratory Sciences and Medical Biotechnology, National Taiwan University, Taipei, Taiwan
| | - Yu-Ting Huang
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yu-Ting Su
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - An-Ni Wang
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Wen-Yen Weng
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Cai-Ling Ke
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yu-Chiao Yeh
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Jhih-Jie Wang
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shin-Hei Du
- Department of Laboratory Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Zi-Qi Gu
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Wei-Lin Chen
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
| | - Ching-Hsuan Lin
- Department of Biochemical Science and Technology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yu-Huan Tsai
- Laboratory of Host–Microbe Interactions and Cell Dynamics, Institute of Microbiology and Immunology, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Program in Molecular Medicine, National Yang Ming Chiao Tung University and Academia Sinica, Taipei, Taiwan
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan
| |
Collapse
|
6
|
Xiong L, Goerlich K, Mitchell AP. Regulatory features of Candida albicans hemin-induced filamentation. G3 (BETHESDA, MD.) 2024; 14:jkae053. [PMID: 38470537 PMCID: PMC11075532 DOI: 10.1093/g3journal/jkae053] [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: 12/04/2023] [Revised: 03/05/2024] [Accepted: 03/07/2024] [Indexed: 03/14/2024]
Abstract
Candida albicans is a prominent fungal pathogen that can infect the bloodstream and deep tissues. One key pathogenicity trait is the ability to transition between yeast and hyphal growth. Hyphae are critical for the formation of biofilms, which in turn enable device-associated infection. Among signals that drive hypha formation is the presence of hemin, an oxidized Fe(III)-containing heme derivative found in blood. In this study, we asked 4 questions. First, how uniform is the filamentation response to hemin among C. albicans strains? We tested 26 diverse isolates and found that the strength of a strain's filamentation response to hemin reflected its filamentation level in the absence of hemin. Second, does hemin induce biofilm formation? Hemin biofilm induction was evident in 5 out of 10 isolates tested, including most of the weaker biofilm formers tested. Third, what is the gene expression response to hemin? We compared RNA-seq data for type strain SC5314 grown in pH 5.5 minimal media with or without hemin. We also compared that response to SC5314 grown in pH 7.0 minimal media, where it undergoes well-studied pH-dependent filamentation. We found a common set of 72 genes with upregulated RNA levels in response to both signals, including many known hypha-associated genes. Surprisingly, overlap among those 72 genes with 2 recent consensus definitions of hypha-associated genes was limited to only 16 genes. Fourth, which regulators govern hemin-induced filamentation? A mutant survey indicated that the response depends upon filamentation regulators Efg1, Brg1, and Rim101, but not upon heme acquisition regulator Hap1 or its target genes HMX1, RBT5, PGA10, PGA7, and CSA2. These findings argue that hemin induces hypha formation independently of its utilization.
Collapse
Affiliation(s)
- Liping Xiong
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Katharina Goerlich
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Aaron P Mitchell
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| |
Collapse
|
7
|
Xiong L, Pereira De Sa N, Zarnowski R, Huang MY, Mota Fernandes C, Lanni F, Andes DR, Del Poeta M, Mitchell AP. Biofilm-associated metabolism via ERG251 in Candida albicans. PLoS Pathog 2024; 20:e1012225. [PMID: 38739655 PMCID: PMC11115363 DOI: 10.1371/journal.ppat.1012225] [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: 01/31/2024] [Revised: 05/23/2024] [Accepted: 04/25/2024] [Indexed: 05/16/2024] Open
Abstract
Biofilm formation by the fungal pathogen Candida albicans is the basis for its ability to infect medical devices. The metabolic gene ERG251 has been identified as a target of biofilm transcriptional regulator Efg1, and here we report that ERG251 is required for biofilm formation but not conventional free-living planktonic growth. An erg251Δ/Δ mutation impairs biofilm formation in vitro and in an in vivo catheter infection model. In both in vitro and in vivo biofilm contexts, cell number is reduced and hyphal length is limited. To determine whether the mutant defect is in growth or some other aspect of biofilm development, we examined planktonic cell features in a biofilm-like environment, which was approximated with sealed unshaken cultures. Under those conditions, the erg251Δ/Δ mutation causes defects in growth and hyphal extension. Overexpression in the erg251Δ/Δ mutant of the paralog ERG25, which is normally expressed more weakly than ERG251, partially improves biofilm formation and biofilm hyphal content, as well as growth and hyphal extension in a biofilm-like environment. GC-MS analysis shows that the erg251Δ/Δ mutation causes a defect in ergosterol accumulation when cells are cultivated under biofilm-like conditions, but not under conventional planktonic conditions. Overexpression of ERG25 in the erg251Δ/Δ mutant causes some increase in ergosterol levels. Finally, the hypersensitivity of efg1Δ/Δ mutants to the ergosterol inhibitor fluconazole is reversed by ERG251 overexpression, arguing that reduced ERG251 expression contributes to this efg1Δ/Δ phenotype. Our results indicate that ERG251 is required for biofilm formation because its high expression levels are necessary for ergosterol synthesis in a biofilm-like environment.
Collapse
Affiliation(s)
- Liping Xiong
- Department of Microbiology, University of Georgia, Athens, Georgia, United States of America
| | - Nivea Pereira De Sa
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, United States of America
| | - Robert Zarnowski
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Manning Y. Huang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Caroline Mota Fernandes
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, United States of America
| | - Frederick Lanni
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - David R. Andes
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Maurizio Del Poeta
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, United States of America
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, United States of America
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| |
Collapse
|
8
|
Iracane E, Arias-Sardá C, Maufrais C, Ene IV, d’Enfert C, Buscaino A. Identification of an active RNAi pathway in Candida albicans. Proc Natl Acad Sci U S A 2024; 121:e2315926121. [PMID: 38625945 PMCID: PMC11047096 DOI: 10.1073/pnas.2315926121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 03/08/2024] [Indexed: 04/18/2024] Open
Abstract
RNA interference (RNAi) is a fundamental regulatory pathway with a wide range of functions, including regulation of gene expression and maintenance of genome stability. Although RNAi is widespread in the fungal kingdom, well-known species, such as the model yeast Saccharomyces cerevisiae, have lost the RNAi pathway. Until now evidence has been lacking for a fully functional RNAi pathway in Candida albicans, a human fungal pathogen considered critically important by the World Health Organization. Here, we demonstrated that the widely used C. albicans reference strain (SC5314) contains an inactivating missense mutation in the gene encoding for the central RNAi component Argonaute. In contrast, most other C. albicans isolates contain a canonical Argonaute protein predicted to be functional and RNAi-active. Indeed, using high-throughput small and long RNA sequencing combined with seamless CRISPR/Cas9-based gene editing, we demonstrate that an active C. albicans RNAi machinery represses expression of subtelomeric gene families. Thus, an intact and functional RNAi pathway exists in C. albicans, highlighting the importance of using multiple reference strains when studying this dangerous pathogen.
Collapse
Affiliation(s)
- Elise Iracane
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
| | - Cristina Arias-Sardá
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
| | - Corinne Maufrais
- Institut Pasteur, Université Paris Cité, Bioinformatic Hub, ParisF-75015, France
| | - Iuliana V. Ene
- Institut Pasteur, Université Paris Cité, Fungal Heterogeneity Group, ParisF-75015, France
| | - Christophe d’Enfert
- Institut Pasteur, Université Paris Cité, Institut national de recherche pour l’agriculture, l’alimentation et l’environnement USC2019, Fungal Biology and Pathogenicity Unit, ParisF-75015, France
| | - Alessia Buscaino
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
| |
Collapse
|
9
|
Bai X, Chen X, Zhang D, Liu X, Li J. Targeted phytogenic compounds against Vibrio parahaemolyticus biofilms. Crit Rev Food Sci Nutr 2024:1-12. [PMID: 38189321 DOI: 10.1080/10408398.2023.2299949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
As one of main culprit of seafood-associated human illness, Vibrio parahaemolyticus can readily accumulate on biotic or abiotic surfaces to form biofilms in the seafood processing environment. Biofilm formation on various surfaces can provide a protective barrier for viable bacterial cells that are resistant to most traditional bacteriostatic measures. This underscores the necessity and urgency of developing effective alternative strategies to control V. parahaemolyticus biofilms. Plants have always provided an extensive and infinite source of biologically active compounds for "green" antibiofilm agents. This review summarizes recent developments in promising multitargeted phytogenic compounds against V. parahaemolyticus biofilms. This review provides valuable insights into potential research targets that can be pursued further to identify potent natural antibiofilm agents in the food industry.
Collapse
Affiliation(s)
- Xue Bai
- College of Food Science and Engineering, Bohai University, Jinzhou, China
| | - Xiaoli Chen
- College of Food Science and Engineering, Bohai University, Jinzhou, China
| | - Defu Zhang
- College of Food Science and Engineering, Bohai University, Jinzhou, China
| | - Xuefei Liu
- College of Food Science and Engineering, Bohai University, Jinzhou, China
| | - Jianrong Li
- College of Food Science and Engineering, Bohai University, Jinzhou, China
| |
Collapse
|
10
|
Glazier VE, Kramara J, Ollinger T, Solis NV, Zarnowski R, Wakade RS, Kim MJ, Weigel GJ, Liang SH, Bennett RJ, Wellington M, Andes DR, Stamnes MA, Filler SG, Krysan DJ. The Candida albicans reference strain SC5314 contains a rare, dominant allele of the transcription factor Rob1 that modulates filamentation, biofilm formation, and oral commensalism. mBio 2023; 14:e0152123. [PMID: 37737633 PMCID: PMC10653842 DOI: 10.1128/mbio.01521-23] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 07/27/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE Candida albicans is a commensal fungus that colonizes the human oral cavity and gastrointestinal tract but also causes mucosal as well as invasive disease. The expression of virulence traits in C. albicans clinical isolates is heterogeneous and the genetic basis of this heterogeneity is of high interest. The C. albicans reference strain SC5314 is highly invasive and expresses robust filamentation and biofilm formation relative to many other clinical isolates. Here, we show that SC5314 derivatives are heterozygous for the transcription factor Rob1 and contain an allele with a rare gain-of-function SNP that drives filamentation, biofilm formation, and virulence in a model of oropharyngeal candidiasis. These findings explain, in part, the outlier phenotype of the reference strain and highlight the role heterozygosity plays in the strain-to-strain variation of diploid fungal pathogens.
Collapse
Affiliation(s)
| | - Juraj Kramara
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Tomye Ollinger
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Norma V. Solis
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute and Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Robert Zarnowski
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, USA
| | - Rohan S. Wakade
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Min-Ju Kim
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Gabriel J. Weigel
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Shen-Huan Liang
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, USA
| | - Richard J. Bennett
- Department of Molecular Microbiology and Immunology, Brown University, Providence, Rhode Island, USA
| | - Melanie Wellington
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - David R. Andes
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin, USA
| | - Mark A. Stamnes
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Scott G. Filler
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute and Harbor-UCLA Medical Center, Torrance, California, USA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Damian J. Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| |
Collapse
|
11
|
Liang X, Chen D, Wang J, Liao B, Shen J, Ye X, Wang Z, Zhu C, Gou L, Zhou X, Cheng L, Ren B, Zhou X. Artemisinins inhibit oral candidiasis caused by Candida albicans through the repression on its hyphal development. Int J Oral Sci 2023; 15:40. [PMID: 37699886 PMCID: PMC10497628 DOI: 10.1038/s41368-023-00245-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 09/14/2023] Open
Abstract
Candida albicans is the most abundant fungal species in oral cavity. As a smart opportunistic pathogen, it increases the virulence by switching its forms from yeasts to hyphae and becomes the major pathogenic agent for oral candidiasis. However, the overuse of current clinical antifungals and lack of new types of drugs highlight the challenges in the antifungal treatments because of the drug resistance and side effects. Anti-virulence strategy is proved as a practical way to develop new types of anti-infective drugs. Here, seven artemisinins, including artemisinin, dihydroartemisinin, artemisinic acid, dihydroartemisinic acid, artesunate, artemether and arteether, were employed to target at the hyphal development, the most important virulence factor of C. albicans. Artemisinins failed to affect the growth, but significantly inhibited the hyphal development of C. albicans, including the clinical azole resistant isolates, and reduced their damage to oral epithelial cells, while arteether showed the strongest activities. The transcriptome suggested that arteether could affect the energy metabolism of C. albicans. Seven artemisinins were then proved to significantly inhibit the productions of ATP and cAMP, while reduced the hyphal inhibition on RAS1 overexpression strain indicating that artemisinins regulated the Ras1-cAMP-Efg1 pathway to inhibit the hyphal development. Importantly, arteether significantly inhibited the fungal burden and infections with no systemic toxicity in the murine oropharyngeal candidiasis models in vivo caused by both fluconazole sensitive and resistant strains. Our results for the first time indicated that artemisinins can be potential antifungal compounds against C. albicans infections by targeting at its hyphal development.
Collapse
Affiliation(s)
- Xiaoyue Liang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ding Chen
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiannan Wang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Binyou Liao
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jiawei Shen
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xingchen Ye
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Zheng Wang
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Chengguang Zhu
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lichen Gou
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xinxuan Zhou
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Lei Cheng
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Biao Ren
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| | - Xuedong Zhou
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & West China Hospital of Stomatology, Sichuan University, Chengdu, China.
- State Key Laboratory of Oral Diseases & National Center for Stomatology & National Clinical Research Center for Oral Diseases & Department of Operative Dentistry and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
| |
Collapse
|
12
|
Sharma A, Mitchell AP. Strain variation in gene expression impact of hyphal cyclin Hgc1 in Candida albicans. G3 (BETHESDA, MD.) 2023; 13:jkad151. [PMID: 37405402 PMCID: PMC10468301 DOI: 10.1093/g3journal/jkad151] [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: 04/30/2023] [Revised: 06/18/2023] [Accepted: 06/20/2023] [Indexed: 07/06/2023]
Abstract
Formation of hyphae is a key virulence trait of the fungal pathogen Candida albicans. Hypha morphogenesis depends upon the cyclin Hgc1, which acts together with cyclin-dependent protein kinase Cdc28 to phosphorylate effectors that drive polarized growth. Hgc1 has also been implicated in gene regulation through its effects on 2 transcription factors, Efg1 and Ume6. Here, we report RNA-sequencing (RNA-seq) analysis of 2 pairs of hgc1Δ/Δ mutants and their respective wild-type strains, which lie in 2 different genetic backgrounds. We find that hgc1Δ/Δ mutations alter expression of 271 genes in both genetic backgrounds and 266 of those genes respond consistently with regard to up- or down-regulation. Consistency is similar to what has been observed with efg1Δ/Δ mutations and greater than observed with nrg1Δ/Δ mutations in these 2 backgrounds. The gene expression response includes genes under Efg1 control, as expected from prior studies. Hgc1-responsive genes also include ergosterol biosynthetic genes and bud neck-related genes, which may reflect interactions between Hgc1 and additional transcription factors as well as effects of Hgc1 on cellular length-to-width ratios.
Collapse
Affiliation(s)
- Anupam Sharma
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| | - Aaron P Mitchell
- Department of Microbiology, University of Georgia, Athens, GA 30602, USA
| |
Collapse
|
13
|
Glazier VE, Kramara J, Ollinger T, Solis NV, Zarnowski R, Wakade RS, Kim MJ, Weigel GJ, Liang SH, Bennett RJ, Wellington M, Andes DR, Stamnes MA, Filler SG, Krysan DJ. The Candida albicans reference strain SC5314 contains a rare, dominant allele of the transcription factor Rob1 that modulates biofilm formation and oral commensalism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.17.545405. [PMID: 37398495 PMCID: PMC10312810 DOI: 10.1101/2023.06.17.545405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Candida albicans is a diploid human fungal pathogen that displays significant genomic and phenotypic heterogeneity over a range of virulence traits and in the context of a variety of environmental niches. Here, we show that the effects of Rob1 on biofilm and filamentation virulence traits is dependent on both the specific environmental condition and the clinical strain of C. albicans . The C. albicans reference strain SC5314 is a ROB1 heterozygote with two alleles that differ by a single nucleotide polymorphism at position 946 resulting in a serine or proline containing isoform. An analysis of 224 sequenced C. albicans genomes indicates that SC5314 is the only ROB1 heterozygote documented to date and that the dominant allele contains a proline at position 946. Remarkably, the ROB1 alleles are functionally distinct and the rare ROB1 946S allele supports increased filamentation in vitro and increased biofilm formation in vitro and in vivo, suggesting it is a phenotypic gain-of-function allele. SC5314 is amongst the most highly filamentous and invasive strains characterized to date. Introduction of the ROB1 946S allele into a poorly filamenting clinical isolate increases filamentation and conversion of an SC5314 laboratory strain to a ROB1 946S homozygote increases in vitro filamentation and biofilm formation. In a mouse model of oropharyngeal infection, the predominant ROB1 946P allele establishes a commensal state while the ROB1 946S phenocopies the parent strain and invades into the mucosae. These observations provide an explanation for the distinct phenotypes of SC5314 and highlight the role of heterozygosity as a driver of C. albicans phenotypic heterogeneity. Importance Candida albicans is a commensal fungus that colonizes human oral cavity and gastrointestinal tracts but also causes mucosal as well as invasive disease. The expression of virulence traits in C. albicans clinical isolates is heterogenous and the genetic basis of this heterogeneity is of high interest. The C. albicans reference strain SC5314 is highly invasive and expresses robust filamentation and biofilm formation relative to many other clinical isolates. Here, we show that SC5314 derivatives are heterozygous for the transcription factor Rob1 and contain an allele with a rare gain-of-function SNP that drives filamentation, biofilm formation, and virulence in a model of oropharyngeal candidiasis. These finding explain, in part, the outlier phenotype of the reference strain and highlight the role of heterozygosity plays in the strain-to-strain variation of diploid fungal pathogens.
Collapse
Affiliation(s)
| | - Juraj Kramara
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
| | - Tomye Ollinger
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
| | - Norma V. Solis
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute and Harbor-UCLA Medical Center, Torrance, CA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Robert Zarnowski
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison WI
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison WI
| | - Rohan S. Wakade
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
| | - Min-Ju Kim
- Department of Microbiology, University of Georgia, Athens, GA
| | - Gabriel J. Weigel
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
| | - Shen-Huan Liang
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI
| | - Richard J. Bennett
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI
| | - Melanie Wellington
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
| | - David R. Andes
- Department of Medicine, Section of Infectious Disease, University of Wisconsin, Madison WI
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison WI
| | - Mark A. Stamnes
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA
| | - Scott G. Filler
- Division of Infectious Diseases, Los Angeles Biomedical Research Institute and Harbor-UCLA Medical Center, Torrance, CA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Damian J. Krysan
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City IA
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City IA
| |
Collapse
|
14
|
Mao Y, Solis NV, Filler SG, Mitchell AP. Functional Dichotomy for a Hyphal Repressor in Candida albicans. mBio 2023; 14:e0013423. [PMID: 36883818 PMCID: PMC10127614 DOI: 10.1128/mbio.00134-23] [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: 01/15/2023] [Accepted: 02/20/2023] [Indexed: 03/09/2023] Open
Abstract
Nrg1 is a repressor of hypha formation and hypha-associated gene expression in the fungal pathogen Candida albicans. It has been well studied in the genetic background of the type strain SC5314. Here, we tested Nrg1 function in four other diverse clinical isolates through an analysis of nrg1Δ/Δ mutants, with SC5314 included as a control. In three strains, nrg1Δ/Δ mutants unexpectedly produced aberrant hyphae under inducing conditions, as assayed by microscopic observation and endothelial cell damage. The nrg1Δ/Δ mutant of strain P57055 had the most severe defect. We examined gene expression features under hypha-inducing conditions by RNA-sequencing (RNA-Seq) for the SC5314 and P57055 backgrounds. The SC5314 nrg1Δ/Δ mutant expressed six hypha-associated genes at reduced levels compared with wild-type SC5314. The P57055 nrg1Δ/Δ mutant expressed 17 hypha-associated genes at reduced levels compared with wild-type P57055, including IRF1, RAS2, and ECE1. These findings indicate that Nrg1 has a positive role in hypha-associated gene expression and that this role is magnified in strain P57055. Remarkably, the same hypha-associated genes affected by the nrg1Δ/Δ mutation in strain P57055 were also naturally expressed at lower levels in wild-type P57055 than those in wild-type SC5314. Our results suggest that strain P57055 is defective in a pathway that acts in parallel with Nrg1 to upregulate the expression of several hypha-associated genes. IMPORTANCE Hypha formation is a central virulence trait of the fungal pathogen Candida albicans. Control of hypha formation has been studied in detail in the type strain but not in other diverse C. albicans clinical isolates. Here, we show that the hyphal repressor Nrg1 has an unexpected positive role in hypha formation and hypha-associated gene expression, as revealed by the sensitized P57055 strain background. Our findings indicate that reliance on a single type strain limits understanding of gene function and illustrate that strain diversity is a valuable resource for C. albicans molecular genetic analysis.
Collapse
Affiliation(s)
- Yinhe Mao
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Norma V. Solis
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
| | - Scott G. Filler
- Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, USA
- David Geffen School of Medicine at UCLA, Los Angeles, California, USA
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| |
Collapse
|