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Firdous Z, Kalra S, Chattopadhyay R, Bari VK. Current insight into the role of mRNA decay pathways in fungal pathogenesis. Microbiol Res 2024; 283:127671. [PMID: 38479232 DOI: 10.1016/j.micres.2024.127671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/19/2024] [Accepted: 02/29/2024] [Indexed: 04/17/2024]
Abstract
Pathogenic fungal species can cause superficial and mucosal infections, to potentially fatal systemic or invasive infections in humans. These infections are more common in immunocompromised or critically ill patients and have a significant morbidity and fatality rate. Fungal pathogens utilize several strategies to adapt the host environment resulting in efficient and comprehensive alterations in their cellular metabolism. Fungal virulence is regulated by several factors and post-transcriptional regulation mechanisms involving mRNA molecules are one of them. Post-transcriptional controls have emerged as critical regulatory mechanisms involved in the pathogenesis of fungal species. The untranslated upstream and downstream regions of the mRNA, as well as RNA-binding proteins, regulate morphogenesis and virulence by controlling mRNA degradation and stability. The limited number of available therapeutic drugs, the emergence of multidrug resistance, and high death rates associated with systemic fungal illnesses pose a serious risk to human health. Therefore, new antifungal treatments that specifically target mRNA pathway components can decrease fungal pathogenicity and when combined increase the effectiveness of currently available antifungal drugs. This review summarizes the mRNA degradation pathways and their role in fungal pathogenesis.
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Affiliation(s)
- Zulikha Firdous
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Sapna Kalra
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Rituja Chattopadhyay
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India
| | - Vinay Kumar Bari
- Department of Biochemistry, School of Basic Sciences, Central University of Punjab, VPO-Ghudda, Bathinda 151401, India.
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2
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Czajka KM, Venkataraman K, Brabant-Kirwan D, Santi SA, Verschoor C, Appanna VD, Singh R, Saunders DP, Tharmalingam S. Molecular Mechanisms Associated with Antifungal Resistance in Pathogenic Candida Species. Cells 2023; 12:2655. [PMID: 37998390 PMCID: PMC10670235 DOI: 10.3390/cells12222655] [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: 10/17/2023] [Revised: 11/14/2023] [Accepted: 11/17/2023] [Indexed: 11/25/2023] Open
Abstract
Candidiasis is a highly pervasive infection posing major health risks, especially for immunocompromised populations. Pathogenic Candida species have evolved intrinsic and acquired resistance to a variety of antifungal medications. The primary goal of this literature review is to summarize the molecular mechanisms associated with antifungal resistance in Candida species. Resistance can be conferred via gain-of-function mutations in target pathway genes or their transcriptional regulators. Therefore, an overview of the known gene mutations is presented for the following antifungals: azoles (fluconazole, voriconazole, posaconazole and itraconazole), echinocandins (caspofungin, anidulafungin and micafungin), polyenes (amphotericin B and nystatin) and 5-fluorocytosine (5-FC). The following mutation hot spots were identified: (1) ergosterol biosynthesis pathway mutations (ERG11 and UPC2), resulting in azole resistance; (2) overexpression of the efflux pumps, promoting azole resistance (transcription factor genes: tac1 and mrr1; transporter genes: CDR1, CDR2, MDR1, PDR16 and SNQ2); (3) cell wall biosynthesis mutations (FKS1, FKS2 and PDR1), conferring resistance to echinocandins; (4) mutations of nucleic acid synthesis/repair genes (FCY1, FCY2 and FUR1), resulting in 5-FC resistance; and (5) biofilm production, promoting general antifungal resistance. This review also provides a summary of standardized inhibitory breakpoints obtained from international guidelines for prominent Candida species. Notably, N. glabrata, P. kudriavzevii and C. auris demonstrate fluconazole resistance.
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Affiliation(s)
- Karolina M. Czajka
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
| | - Krishnan Venkataraman
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | | | - Stacey A. Santi
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Chris Verschoor
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Vasu D. Appanna
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
| | - Ravi Singh
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Deborah P. Saunders
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
| | - Sujeenthar Tharmalingam
- Medical Sciences Division, NOSM University, 935 Ramsey Lake Rd., Sudbury, ON P3E 2C6, Canada; (K.M.C.); (K.V.); (C.V.); (R.S.); (D.P.S.)
- School of Natural Sciences, Laurentian University, Sudbury, ON P3E 2C6, Canada;
- Health Sciences North Research Institute, Sudbury, ON P3E 2H2, Canada; (D.B.-K.); (S.A.S.)
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3
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Stover KR, Hawkins BK, Keck JM, Barber KE, Cretella DA. Antifungal resistance, combinations and pipeline: oh my! Drugs Context 2023; 12:2023-7-1. [PMID: 38021410 PMCID: PMC10653594 DOI: 10.7573/dic.2023-7-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/26/2023] [Indexed: 12/01/2023] Open
Abstract
Invasive fungal infections are a strong contributor to healthcare costs, morbidity and mortality, especially amongst hospitalized patients. Historically, Candida was responsible for approximately 15% of all nosocomial bloodstream infections. In the past 10 years, the epidemiology of Candida species has altered, with increasing prevalence of resistant species. With rising fungal resistance, especially in Candida spp., the demand for novel antifungal therapies has exponentially increased over the last decade. Newer antifungal agents have become an attractive option for patients needing long-term therapy for infections or those requiring antifungal prophylaxis. Despite advances in coverage of non-Candida pathogens with newer agents, clinical scenarios involving multidrug-resistant fungal pathogens continue to arise in practice. Combination antifungal therapy can lead to a host of side-effects, some of which can be drug limiting. Additional antifungal therapies with enhanced fungal spectrum of activity and decreased rates of adverse effects are warranted. Fosmanogepix, ibrexafungerp, olorofim and rezafungin may help fill some of these gaps in the antifungal armamentarium. This article is part of the Challenges and strategies in the management of invasive fungal infections Special Issue: https://www.drugsincontext.com/special_issues/challenges-and-strategies-in-the-management-of-invasive-fungal-infections.
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Affiliation(s)
- Kayla R Stover
- Department of Pharmacy Practice, University of Mississippi School of Pharmacy, Jackson, MS, USA
| | - Brandon K Hawkins
- Department of Clinical Pharmacy and Translational Science, The University of Tennessee Health Science Center, Knoxville, TN, USA
| | - J Myles Keck
- Department of Pharmacy, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Katie E Barber
- Department of Pharmacy Practice, University of Mississippi School of Pharmacy, Jackson, MS, USA
| | - David A Cretella
- Division of Infectious Diseases, University of Mississippi Medical Center, Jackson, MS, USA
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4
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Sharma C, Kadosh D. Post-transcriptional control of antifungal resistance in human fungal pathogens. Crit Rev Microbiol 2023; 49:469-484. [PMID: 35634915 PMCID: PMC9766424 DOI: 10.1080/1040841x.2022.2080527] [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: 01/12/2022] [Revised: 05/10/2022] [Accepted: 05/17/2022] [Indexed: 11/03/2022]
Abstract
Global estimates suggest that over 300 million individuals of all ages are affected by serious fungal infections every year, culminating in about 1.7 million deaths. The societal and economic burden on the public health sector due to opportunistic fungal pathogens is quite significant, especially among immunocompromised patients. Despite the high clinical significance of these infectious agents, treatment options are limited with only three major classes of antifungal drugs approved for use. Clinical management of fungal diseases is further compromised by the emergence of antifungal resistant strains. Transcriptional and genetic mechanisms that control drug resistance in human fungal pathogens are well-studied and include drug target alteration, upregulation of drug efflux pumps as well as changes in drug affinity and abundance of target proteins. In this review, we highlight several recently discovered novel post-transcriptional mechanisms that control antifungal resistance, which involve regulation at the translational, post-translational, epigenetic, and mRNA stability levels. The discovery of many of these novel mechanisms has opened new avenues for the development of more effective antifungal treatment strategies and new insights, perspectives, and future directions that will facilitate this process are discussed.
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Affiliation(s)
- Cheshta Sharma
- Department of Microbiology, Immunology and Molecular Genetics University of Texas Health Science Center at San Antonio, San Antonio, TX
| | - David Kadosh
- Department of Microbiology, Immunology and Molecular Genetics University of Texas Health Science Center at San Antonio, San Antonio, TX
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Alastruey-Izquierdo A, Martín-Galiano AJ. The challenges of the genome-based identification of antifungal resistance in the clinical routine. Front Microbiol 2023; 14:1134755. [PMID: 37152754 PMCID: PMC10157239 DOI: 10.3389/fmicb.2023.1134755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 04/05/2023] [Indexed: 05/09/2023] Open
Abstract
The increasing number of chronic and life-threatening infections caused by antimicrobial resistant fungal isolates is of critical concern. Low DNA sequencing cost may facilitate the identification of the genomic profile leading to resistance, the resistome, to rationally optimize the design of antifungal therapies. However, compared to bacteria, initiatives for resistome detection in eukaryotic pathogens are underdeveloped. Firstly, reported mutations in antifungal targets leading to reduced susceptibility must be extensively collected from the literature to generate comprehensive databases. This information should be complemented with specific laboratory screenings to detect the highest number possible of relevant genetic changes in primary targets and associations between resistance and other genomic markers. Strikingly, some drug resistant strains experience high-level genetic changes such as ploidy variation as much as duplications and reorganizations of specific chromosomes. Such variations involve allelic dominance, gene dosage increments and target expression regime effects that should be explicitly parameterized in antifungal resistome prediction algorithms. Clinical data indicate that predictors need to consider the precise pathogen species and drug levels of detail, instead of just genus and drug class. The concomitant needs for mutation accuracy and assembly quality assurance suggest hybrid sequencing approaches involving third-generation methods will be utilized. Moreover, fatal fast infections, like fungemia and meningitis, will further require both sequencing and analysis facilities are available in-house. Altogether, the complex nature of antifungal resistance demands extensive sequencing, data acquisition and processing, bioinformatic analysis pipelines, and standard protocols to be accomplished prior to genome-based protocols are applied in the clinical setting.
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Affiliation(s)
- Ana Alastruey-Izquierdo
- Mycology Reference Laboratory, National Centre for Microbiology, Instituto de Salud Carlos III, Madrid, Spain
- Center for Biomedical Research in Network in Infectious Diseases (CIBERINFEC-CB21/13/00105), Instituto de Salud Carlos III, Madrid, Spain
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6
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Taylor MB, Skophammer R, Warwick AR, Geck RC, Boyer JM, Walson M, Large CRL, Hickey ASM, Rowley PA, Dunham MJ. yEvo: experimental evolution in high school classrooms selects for novel mutations that impact clotrimazole resistance in Saccharomyces cerevisiae. G3 (BETHESDA, MD.) 2022; 12:jkac246. [PMID: 36173330 PMCID: PMC9635649 DOI: 10.1093/g3journal/jkac246] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022]
Abstract
Antifungal resistance in pathogenic fungi is a growing global health concern. Nonpathogenic laboratory strains of Saccharomyces cerevisiae are an important model for studying mechanisms of antifungal resistance that are relevant to understanding the same processes in pathogenic fungi. We have developed a series of laboratory modules in which high school students used experimental evolution to study antifungal resistance by isolating azole-resistant S. cerevisiae mutants and examining the genetic basis of resistance. We have sequenced 99 clones from these experiments and found that all possessed mutations previously shown to impact azole resistance, validating our approach. We additionally found recurrent mutations in an mRNA degradation pathway and an uncharacterized mitochondrial protein (Csf1) that have possible mechanistic connections to azole resistance. The scale of replication in this initiative allowed us to identify candidate epistatic interactions, as evidenced by pairs of mutations that occur in the same clone more frequently than expected by chance (positive epistasis) or less frequently (negative epistasis). We validated one of these pairs, a negative epistatic interaction between gain-of-function mutations in the multidrug resistance transcription factors Pdr1 and Pdr3. This high school-university collaboration can serve as a model for involving members of the broader public in the scientific process to make meaningful discoveries in biomedical research.
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Affiliation(s)
- Matthew Bryce Taylor
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- Program in Biology, Loras College, Dubuque, IA 52001, USA
| | | | - Alexa R Warwick
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA
| | - Renee C Geck
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Josephine M Boyer
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - yEvo Students
- Westridge School, Pasadena, CA 91105, USA
- Moscow High School, Moscow, ID 83843, USA
| | - Margaux Walson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Christopher R L Large
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- UW Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Angela Shang-Mei Hickey
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
- Present address: Department of Genetics, Stanford University, Biomedical Innovations Building, Palo Alto, CA 94304, USA
| | - Paul A Rowley
- Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Maitreya J Dunham
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
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7
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Wang WY, Cai HQ, Qu SY, Lin WH, Liang CC, Liu H, Xie ZX, Yuan YJ. Genomic Variation-Mediating Fluconazole Resistance in Yeast. Biomolecules 2022; 12:biom12060845. [PMID: 35740970 PMCID: PMC9221393 DOI: 10.3390/biom12060845] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/07/2022] [Accepted: 06/09/2022] [Indexed: 11/16/2022] Open
Abstract
Fungal infections pose a serious and growing threat to public health. These infections can be treated with antifungal drugs by killing hazardous fungi in the body. However, the resistance can develop over time when fungi are exposed to antifungal drugs by generating genomic variations, including mutation, aneuploidy, and loss of heterozygosity. The variations could reduce the binding affinity of a drug to its target or block the pathway through which drugs exert their activity. Here, we review genomic variation-mediating fluconazole resistance in the yeast Candida, with the hope of highlighting the functional consequences of genomic variations for the antifungal resistance.
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8
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Mba IE, Nweze EI, Eze EA, Anyaegbunam ZKG. Genome plasticity in Candida albicans: A cutting-edge strategy for evolution, adaptation, and survival. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 99:105256. [PMID: 35231665 DOI: 10.1016/j.meegid.2022.105256] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 09/12/2021] [Accepted: 02/22/2022] [Indexed: 12/15/2022]
Abstract
Candida albicans is the most implicated fungal species that grows as a commensal or opportunistic pathogen in the human host. It is associated with many life-threatening infections, especially in immunocompromised persons. The genome of Candida albicans is very flexible and can withstand a wide assortment of variations in a continuously changing environment. Thus, genome plasticity is central to its adaptation and has long been of considerable interest. C. albicans has a diploid heterozygous genome that is highly dynamic and can display variation from small to large scale chromosomal rearrangement and aneuploidy, which have implications in drug resistance, virulence, and pathogenicity. This review presents an up-to-date overview of recent genomic studies involving C. albicans. It discusses the accumulating evidence that shows how mitotic recombination events, ploidy dynamics, aneuploidy, and loss of heterozygosity (LOH) influence evolution, adaptation, and survival in C. albicans. Understanding the factors that affect the genome is crucial for a proper understanding of species and rapid development and adjustment of therapeutic strategies to mitigate their spread.
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Affiliation(s)
| | | | | | - Zikora Kizito Glory Anyaegbunam
- Institution for Drug-Herbal Medicine-Excipient-Research and Development, Faculty of Pharmaceutical Sciences, Nsukka, Nigeria
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Rana A, Gupta N, Thakur A. Post-transcriptional and translational control of the morphology and virulence in human fungal pathogens. Mol Aspects Med 2021; 81:101017. [PMID: 34497025 DOI: 10.1016/j.mam.2021.101017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 08/13/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022]
Abstract
Host-pathogen interactions at the molecular level are the key to fungal pathogenesis. Fungal pathogens utilize several mechanisms such as adhesion, invasion, phenotype switching and metabolic adaptations, to survive in the host environment and respond. Post-transcriptional and translational regulations have emerged as key regulatory mechanisms ensuring the virulence and survival of fungal pathogens. Through these regulations, fungal pathogens effectively alter their protein pool, respond to various stress, and undergo morphogenesis, leading to efficient and comprehensive changes in fungal physiology. The regulation of virulence through post-transcriptional and translational regulatory mechanisms is mediated through mRNA elements (cis factors) or effector molecules (trans factors). The untranslated regions upstream and downstream of the mRNA, as well as various RNA-binding proteins involved in translation initiation or circularization of the mRNA, play pivotal roles in the regulation of morphology and virulence by influencing protein synthesis, protein isoforms, and mRNA stability. Therefore, post-transcriptional and translational mechanisms regulating the morphology, virulence and drug-resistance processes in fungal pathogens can be the target for new therapeutics. With improved "omics" technologies, these regulatory mechanisms are increasingly coming to the forefront of basic biology and drug discovery. This review aims to discuss various modes of post-transcriptional and translation regulations, and how these mechanisms exert influence in the virulence and morphogenesis of fungal pathogens.
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Affiliation(s)
- Aishwarya Rana
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India
| | - Nidhi Gupta
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India
| | - Anil Thakur
- Regional Centre for Biotechnology, 3rd Milestone Gurgaon-Faridabad Expressway, Faridabad 121001, India.
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10
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Nishimoto AT, Sharma C, Rogers PD. Molecular and genetic basis of azole antifungal resistance in the opportunistic pathogenic fungus Candida albicans. J Antimicrob Chemother 2021; 75:257-270. [PMID: 31603213 DOI: 10.1093/jac/dkz400] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Candida albicans is an opportunistic yeast and the major human fungal pathogen in the USA, as well as in many other regions of the world. Infections with C. albicans can range from superficial mucosal and dermatological infections to life-threatening infections of the bloodstream and vital organs. The azole antifungals remain an important mainstay treatment of candidiasis and therefore the investigation and understanding of the evolution, frequency and mechanisms of azole resistance are vital to improving treatment strategies against this organism. Here the organism C. albicans and the genetic changes and molecular bases underlying the currently known resistance mechanisms to the azole antifungal class are reviewed, including up-regulated expression of efflux pumps, changes in the expression and amino acid composition of the azole target Erg11 and alterations to the organism's typical sterol biosynthesis pathways. Additionally, we update what is known about activating mutations in the zinc cluster transcription factor (ZCF) genes regulating many of these resistance mechanisms and review azole import as a potential contributor to azole resistance. Lastly, investigations of azole tolerance in C. albicans and its implicated clinical significance are reviewed.
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Affiliation(s)
- Andrew T Nishimoto
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Cheshta Sharma
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - P David Rogers
- Department of Clinical Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
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11
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The Impact of Gene Dosage and Heterozygosity on The Diploid Pathobiont Candida albicans. J Fungi (Basel) 2019; 6:jof6010010. [PMID: 31892130 PMCID: PMC7151161 DOI: 10.3390/jof6010010] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 12/14/2019] [Accepted: 12/18/2019] [Indexed: 12/29/2022] Open
Abstract
Candida albicans is a fungal species that can colonize multiple niches in the human host where it can grow either as a commensal or as an opportunistic pathogen. The genome of C. albicans has long been of considerable interest, given that it is highly plastic and can undergo a wide variety of alterations. These changes play a fundamental role in determining C. albicans traits and have been shown to enable adaptation both to the host and to antifungal drugs. C. albicans isolates contain a heterozygous diploid genome that displays variation from the level of single nucleotides to largescale rearrangements and aneuploidy. The heterozygous nature of the genome is now increasingly recognized as being central to C. albicans biology, as the relative fitness of isolates has been shown to correlate with higher levels of overall heterozygosity. Moreover, loss of heterozygosity (LOH) events can arise frequently, either at single polymorphisms or at a chromosomal level, and both can alter the behavior of C. albicans cells during infection or can modulate drug resistance. In this review, we examine genome plasticity in this pathobiont focusing on how gene dosage variation and loss of heterozygosity events can arise and how these modulate C. albicans behavior.
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12
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Prasad R, Balzi E, Banerjee A, Khandelwal NK. All about CDR transporters: Past, present, and future. Yeast 2018; 36:223-233. [DOI: 10.1002/yea.3356] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 08/20/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Affiliation(s)
- Rajendra Prasad
- Amity Institute of Biotechnology and Amity Institute of Integrative Sciences and HealthAmity University Haryana Gurgaon India
| | - Elisabetta Balzi
- Unité de Biochimie PhysiologiqueUniversité Catholique de Louvain Ottignies‐Louvain‐la‐Neuve Belgium
| | - Atanu Banerjee
- School of Life SciencesJawaharlal Nehru University New Delhi India
- School of Computational and Integrative SciencesJawaharlal Nehru University New Delhi India
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13
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Dias IJ, Trajano ERIS, Castro RD, Ferreira GLS, Medeiros HCM, Gomes DQC. Antifungal activity of linalool in cases of Candida spp. isolated from individuals with oral candidiasis. BRAZ J BIOL 2017; 78:368-374. [PMID: 28977047 DOI: 10.1590/1519-6984.171054] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/21/2016] [Indexed: 02/07/2023] Open
Abstract
This study analyzed the antifungal activity of phytoconstituents from linalool on Candida spp. strains, in vitro, isolated from patients with clinical diagnoses of oral candidiasis associated with the use of a dental prosthesis. Biological samples were collected from 12 patients using complete dentures or removable partial dentures and who presented mucous with diffuse erythematous or stippled features, indicating a clinical diagnosis of candidiasis. To identify fungal colonies of the genus Candida, samples were plated onto CHROMagar Candida®. The antifungal activity of linalool, a monoterpene unsaturated constituent of basil oil, was performed using the broth microdilution technique. Then, the minimum inhibitory concentration (MIC), the two subsequent stronger concentrations and the positive controls were subcultured on Sabouraud Dextrose Agar plates to determine the minimum fungicidal concentration (MFC). The experiments were performed in triplicate and nystatin was used as a positive control in all tests. Diagnoses of oral candidiasis were verified in eight patients (66.6%) and the most prevalent fungal species was Candida albicans (37.5%), followed by Candida krusei (25.0%); and Candida tropicalis (4.2%). The best antifungal activity of linalool was observed on Candida tropicalis (MIC = 500 mg/mL), followed by Candida albicans (MIC = 1.000 mg/mL), and Candida krusei (MIC = 2.000 mg/mL).Under the study conditions and based on the results obtained, it can be concluded that the Candida strains tested were susceptible to linalool.
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Affiliation(s)
- I J Dias
- Departamento de Odontologia, Universidade Estadual da Paraíba, Campina Grande, PB, Brazil
| | - E R I S Trajano
- Departamento de Odontologia, Universidade Estadual da Paraíba, Campina Grande, PB, Brazil
| | - R D Castro
- Departamento de Odontologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil
| | - G L S Ferreira
- Departamento de Odontologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil
| | - H C M Medeiros
- Departamento de Odontologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil
| | - D Q C Gomes
- Departamento de Odontologia, Universidade Estadual da Paraíba, Campina Grande, PB, Brazil
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14
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Kadosh D. Control of Candida albicans morphology and pathogenicity by post-transcriptional mechanisms. Cell Mol Life Sci 2016; 73:4265-4278. [PMID: 27312239 PMCID: PMC5582595 DOI: 10.1007/s00018-016-2294-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 05/23/2016] [Accepted: 06/10/2016] [Indexed: 02/01/2023]
Abstract
Candida albicans is a major human fungal pathogen responsible for both systemic and mucosal infections in a wide variety of immunocompromised individuals. Because the ability of C. albicans to undergo a reversible morphological transition from yeast to filaments is important for virulence, significant research efforts have focused on mechanisms that control this transition. While transcriptional and post-translational mechanisms have been well-studied, considerably less is known about the role of post-transcriptional mechanisms. However, in recent years several discoveries have begun to shed light on this important, but understudied, area. Here, I will review a variety of post-transcriptional mechanisms that have recently been shown to control C. albicans morphology, virulence and/or virulence-related processes, including those involving alternative transcript localization, mRNA stability and translation. I will also discuss the role that these mechanisms play in other pathogens as well as the potential they may hold to serve as targets for new antifungal strategies. Ultimately, gaining a better understanding of C. albicans post-transcriptional mechanisms will significantly improve our knowledge of how morphogenesis and virulence are controlled in fungal pathogens and open new avenues for the development of novel and more effective antifungals.
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Affiliation(s)
- David Kadosh
- Department of Microbiology and Immunology, University of Texas Health Science, Center at San Antonio, 7703 Floyd Curl Drive, MC: 7758, San Antonio, TX, 78229, USA.
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de Castro RD, de Souza TMPA, Bezerra LMD, Ferreira GLS, de Brito Costa EMM, Cavalcanti AL. Antifungal activity and mode of action of thymol and its synergism with nystatin against Candida species involved with infections in the oral cavity: an in vitro study. Altern Ther Health Med 2015; 15:417. [PMID: 26601661 PMCID: PMC4659158 DOI: 10.1186/s12906-015-0947-2] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/21/2015] [Indexed: 01/16/2023]
Abstract
BACKGROUND Limitations of antifungal agents used in the treatment of oral candidiasis, as the development of resistant strains, are known by the scientific community. In this context, the aim of this study was to evaluate the antifungal activity of thymol against Candida albicans, Candida tropicalis and Candida krusei strains and to determine its mode of action and synergistic effect when combined with the synthetic antifungal nystatin. METHODS The minimum inhibitory concentration (MIC) was determined using a microdilution technique, and the minimum fungicidal concentration (MFC) was determined via subculture sowing. The mode of action of thymol was established by verifying fungal growth in the presence of sorbitol or ergosterol. The fractional inhibitory concentration index (FIC) was determined using the checkerboard method. RESULTS Thymol presented an antifungal effect, with MICs of 39 μg/mL for C. albicans and C. krusei and 78 μg/mL for C. tropicalis. The results of the antifungal test remained unchanged in the presence of sorbitol; however, the MIC value of thymol against C. albicans increased eight times (from 39.0 to 312.5 μg/mL) in presence of exogenous ergosterol. The combination of thymol and nystatin reduced the MIC values of both products by 87.4%, generating an FIC index of 0.25. CONCLUSIONS Thymol was found to have a fungicidal effect on Candida species and a synergistic effect when combined with nystatin.
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Abstract
In the light of multidrug resistance (MDR) among pathogenic microbes and cancer cells, membrane transporters have gained profound clinical significance. Chemotherapeutic failure, by far, has been attributed mainly to the robust and diverse array of these proteins, which are omnipresent in every stratum of the living world. Candida albicans, one of the major fungal pathogens affecting immunocompromised patients, also develops MDR during the course of chemotherapy. The pivotal membrane transporters that C. albicans has exploited as one of the strategies to develop MDR belongs to either the ATP binding cassette (ABC) or the major facilitator superfamily (MFS) class of proteins. The ABC transporter Candida drug resistance 1 protein (Cdr1p) is a major player among these transporters that enables the pathogen to outplay the battery of antifungals encountered by it. The promiscuous Cdr1 protein fulfills the quintessential need of a model to study molecular mechanisms of multidrug transporter regulation and structure-function analyses of asymmetric ABC transporters. In this review, we cover the highlights of two decades of research on Cdr1p that has provided a platform to study its structure-function relationships and regulatory circuitry for a better understanding of MDR not only in yeast but also in other organisms.
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Cowen LE, Sanglard D, Howard SJ, Rogers PD, Perlin DS. Mechanisms of Antifungal Drug Resistance. Cold Spring Harb Perspect Med 2014; 5:a019752. [PMID: 25384768 DOI: 10.1101/cshperspect.a019752] [Citation(s) in RCA: 354] [Impact Index Per Article: 35.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Antifungal therapy is a central component of patient management for acute and chronic mycoses. Yet, treatment choices are restricted because of the sparse number of antifungal drug classes. Clinical management of fungal diseases is further compromised by the emergence of antifungal drug resistance, which eliminates available drug classes as treatment options. Once considered a rare occurrence, antifungal drug resistance is on the rise in many high-risk medical centers. Most concerning is the evolution of multidrug- resistant organisms refractory to several different classes of antifungal agents, especially among common Candida species. The mechanisms responsible are mostly shared by both resistant strains displaying inherently reduced susceptibility and those acquiring resistance during therapy. The molecular mechanisms include altered drug affinity and target abundance, reduced intracellular drug levels caused by efflux pumps, and formation of biofilms. New insights into genetic factors regulating these mechanisms, as well as cellular factors important for stress adaptation, provide a foundation to better understand the emergence of antifungal drug resistance.
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Affiliation(s)
- Leah E Cowen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Dominique Sanglard
- University of Lausanne and University Hospital Center, Institute of Microbiology, 1011 Lausanne, Switzerland
| | - Susan J Howard
- University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, United Kingdom
| | - P David Rogers
- College of Pharmacy, The University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - David S Perlin
- Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey 07103
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Novel Regulatory Mechanisms of Pathogenicity and Virulence to Combat MDR in Candida albicans. Int J Microbiol 2013; 2013:240209. [PMID: 24163696 PMCID: PMC3791847 DOI: 10.1155/2013/240209] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Revised: 08/15/2013] [Accepted: 08/15/2013] [Indexed: 01/19/2023] Open
Abstract
Continuous deployment of antifungals in treating infections caused by dimorphic opportunistic pathogen Candida albicans has led to the emergence of drug resistance resulting in cross-resistance to many unrelated drugs, a phenomenon termed multidrug resistance (MDR). Despite the current understanding of major factors which contribute to MDR mechanisms, there are many lines of evidence suggesting that it is a complex interplay of multiple factors which may be contributed by still unknown mechanisms. Coincidentally with the increased usage of antifungal drugs, the number of reports for antifungal drug resistance has also increased which further highlights the need for understanding novel molecular mechanisms which can be explored to combat MDR, namely, ROS, iron, hypoxia, lipids, morphogenesis, and transcriptional and signaling networks. Considering the worrying evolution of MDR and significance of C. albicans being the most prevalent human fungal pathogen, this review summarizes these new regulatory mechanisms which could be exploited to prevent MDR development in C. albicans as established from recent studies.
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Srikantha T, Daniels KJ, Pujol C, Sahni N, Yi S, Soll DR. Nonsex genes in the mating type locus of Candida albicans play roles in a/α biofilm formation, including impermeability and fluconazole resistance. PLoS Pathog 2012; 8:e1002476. [PMID: 22253594 PMCID: PMC3257300 DOI: 10.1371/journal.ppat.1002476] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 11/22/2011] [Indexed: 12/24/2022] Open
Abstract
The mating type locus (MTL) of Candida albicans contains the mating type genes and has, therefore, been assumed to play an exclusive role in the mating process. In mating-incompetent a/α cells, two of the mating type genes, MTLa1 and MTLα2, encode components of the a1-α2 corepressor that suppresses mating and switching. But the MTL locus of C. albicans also contains three apparently unrelated “nonsex” genes (NSGs), PIK, PAP and OBP, the first two essential for growth. Since it had been previously demonstrated that deleting either the a/α copy of the entire MTL locus, or either MTLa1 or MTLα2, affected virulence, we hypothesized that the NSGs in the MTL locus may also play a role in pathogenesis. Here by mutational analysis, it is demonstrated that both the mating type and nonsex genes in the MTL locus play roles in a/α biofilm formation, and that OBP is essential for impermeability and fluconazole resistance. Most natural strains of the yeast pathogen Candida albicans are diploid and heterozygous (a/α) at the mating type locus (MTL). The MTL locus contains mating type genes and has been assumed to play roles exclusively in the mating process of a/a and α/α cells. In C. albicans, however, the MTL locus also contains three nonsex genes (NSGs), the essential phosphatidyl inositol kinase gene, PIK, the essential poly(A) polymerase gene, PAP, and the nonessential oxysterol binding protein gene, OBP. We demonstrate for the first time that both the mating type genes MTLa1 and MTLα2, and the three NSGs play non-mating roles in a/α biofilm formation and virulence. In addition, we show that the NSG OBP is necessary for impermeability and fluconazole resistance of a/α biofilms. These results demonstrate that nonsex genes as well as two mating type genes embedded in the mating type locus, play related roles in pathogenic processes unrelated to mating in a/α cells.
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Affiliation(s)
- Thyagarajan Srikantha
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Karla J. Daniels
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Claude Pujol
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Nidhi Sahni
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Song Yi
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - David R. Soll
- The Developmental Studies Hybridoma Bank, Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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Ncb2 is involved in activated transcription of CDR1 in azole-resistant clinical isolates of Candida albicans. EUKARYOTIC CELL 2011; 10:1357-66. [PMID: 21856931 DOI: 10.1128/ec.05041-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We recently demonstrated that CDR1 overexpression in azole-resistant isolates of Candida albicans is due to its enhanced transcriptional activation and increased mRNA stability. In this study, we provide the first evidence of transcriptional regulation of CDR1 by Ncb2, the β subunit of NC2, a heterodimeric regulator of transcription. Conditional NCB2 null mutants displayed decreased susceptibility toward azole and an enhanced transcription of CDR1. Interestingly, Ncb2 associated with the CDR1 promoter under both repression and activation; however, an increase in recruitment was observed under both transient and constitutive activation states. By chromatin immunoprecipitation (ChIP) assay, we showed the preferential recruitment of Ncb2 to the core TATA region under activation (azole-resistant isolate), while under repression (azole-susceptible isolate) it was present at the TATA upstream region. Further, ChIP analysis revealed that Ncb2 binding was not restricted to the CDR1 gene; instead, it was observed on the promoters of genes coregulated with CDR1 by the transcription activator Tac1. The tac1Δ null mutants, which fail to show the drug-induced transient activation of CDR1, also showed no increase in Ncb2 recruitment at the promoter. Taken together, our results show that Ncb2, in conjunction with Tac1, is involved in the transcriptional activation of CDR1, opening up new therapeutic possibilities to combat multidrug resistance (MDR) in C. albicans.
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Loss of heterozygosity at an unlinked genomic locus is responsible for the phenotype of a Candida albicans sap4Δ sap5Δ sap6Δ mutant. EUKARYOTIC CELL 2010; 10:54-62. [PMID: 21097666 DOI: 10.1128/ec.00281-10] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The diploid genome of the pathogenic yeast Candida albicans exhibits a high degree of heterozygosity. Genomic alterations that result in a loss of heterozygosity at specific loci may affect phenotypes and confer a selective advantage under certain conditions. Such genomic rearrangements can also occur during the construction of C. albicans mutants and remain undetected. The SAP2 gene on chromosome R encodes a secreted aspartic protease that is induced and required for growth of C. albicans when proteins are the only available nitrogen source. In strain SC5314, the two SAP2 alleles are functionally divergent because of differences in their regulation. Basal expression of the SAP2-2 allele, but not the SAP2-1 allele, provides the proteolytic degradation products that serve as inducers for full SAP2 induction. A triple mutant lacking the SAP4, SAP5, and SAP6 genes, which are located on chromosome 6, has previously been reported to have a growth defect on proteins, suggesting that one of the encoded proteases is required for SAP2 expression. Here we show that this sap4Δ sap5Δ sap6Δ mutant has become homozygous for chromosome R and lost the SAP2-2 allele. Replacement of one of the SAP2-1 copies in this strain by SAP2-2 and its regulatory region restored the ability of the sap4Δ sap5Δ sap6Δ mutant to utilize proteins as the sole nitrogen source. This is an illustrative example of how loss of heterozygosity at a different genomic locus can cause the mutant phenotype attributed to targeted deletion of a specific gene in C. albicans.
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Molecular determinants of transient and reversible induced up-regulation of CaCDR1 in azole susceptible clinical isolates of Candida albicans. Biosci Rep 2010; 31:31-43. [DOI: 10.1042/bsr20100015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The present study examines the molecular mechanism underlying in vitro-induced resistance to FLC (fluconazole), KTC (ketaonazole), MCZ (miconazole) and CHX (cycloheximide) in AS (azole-susceptible) strains of Candida albicans when exposed to CaCDR1/CaCDR2 inducers like FPZ (fluphenazine) and steroids [PRG (progesterone) and β-EST (β-oestradiol)]. By employing spot and checkerboard titre assays, we provide evidence of an in vitro-induced antagonism between tested drugs and inducers, which was accompanied with a concomitant increase in CaCDR1 and CaCDR2 transcript levels. Notably, unlike AS isolates, parental WT (wild-type) and Δcdr2 null strains, Δcdr1 as well as Δcdr1/Δcdr2 nulls, when challenged with the inducers could not display antagonism. Our results validated by Northern blotting, reporter gene transcription and TRO (transcription run on) assays show that in vitro-induced antagonism between tested drugs and inducer in AS isolates was mainly due to a transient and reversible transcriptional activation of CaCDR1. Notwithstanding our earlier observation that consistent high transcript levels of CaCDR1 in clinical AR (azole-resistant) isolates were maintained due to the combination of its transcriptional activation and enhanced mRNA stability via elongated poly(A) tails, this study shows that transient and reversible transcriptional activation of CaCDR1 was the major determinant of induced antagonism in AS isolates. The distinct strategies between sustained (in AR isolates) and transiently induced resistance mechanisms (in AS isolates) adopted by Candida should become useful in improving therapeutic approaches.
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Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Selmecki A, Forche A, Berman J. Genomic plasticity of the human fungal pathogen Candida albicans. EUKARYOTIC CELL 2010; 9:991-1008. [PMID: 20495058 PMCID: PMC2901674 DOI: 10.1128/ec.00060-10] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The genomic plasticity of Candida albicans, a commensal and common opportunistic fungal pathogen, continues to reveal unexpected surprises. Once thought to be asexual, we now know that the organism can generate genetic diversity through several mechanisms, including mating between cells of the opposite or of the same mating type and by a parasexual reduction in chromosome number that can be accompanied by recombination events (2, 12, 14, 53, 77, 115). In addition, dramatic genome changes can appear quite rapidly in mitotic cells propagated in vitro as well as in vivo. The detection of aneuploidy in other fungal pathogens isolated directly from patients (145) and from environmental samples (71) suggests that variations in chromosome organization and copy number are a common mechanism used by pathogenic fungi to rapidly generate diversity in response to stressful growth conditions, including, but not limited to, antifungal drug exposure. Since cancer cells often become polyploid and/or aneuploid, some of the lessons learned from studies of genome plasticity in C. albicans may provide important insights into how these processes occur in higher-eukaryotic cells exposed to stresses such as anticancer drugs.
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Affiliation(s)
- Anna Selmecki
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Anja Forche
- Department of Biology, Bowdoin College, Brunswick, Maine
| | - Judith Berman
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota
- Department of Microbiology, University of Minnesota, Minneapolis, Minnesota
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