Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>

ABSTRACT While the folate biosynthetic pathway has provided a rich source of antibacterial, antiprotozoal, and anticancer therapies, it has not yet been exploited to develop uniquely antifungal agents. Although there have been attempts to develop fungal-specific inhibitors of dihydrofolate reductase...

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Autores principales:	Christian DeJarnette, Arturo Luna-Tapia, Leanna R. Estredge, Glen E. Palmer
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	Candida albicans antifungal agents dihydrofolate reductase Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/7bedfb15049f4488a03cf31477b69091
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spelling	oai:doaj.org-article:7bedfb15049f4488a03cf31477b690912021-11-15T15:30:15ZDihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>10.1128/mSphere.00374-202379-5042https://doaj.org/article/7bedfb15049f4488a03cf31477b690912020-06-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00374-20https://doaj.org/toc/2379-5042ABSTRACT While the folate biosynthetic pathway has provided a rich source of antibacterial, antiprotozoal, and anticancer therapies, it has not yet been exploited to develop uniquely antifungal agents. Although there have been attempts to develop fungal-specific inhibitors of dihydrofolate reductase (DHFR), the protein itself has not been unequivocally validated as essential for fungal growth or virulence. The purpose of this study was to establish dihydrofolate reductase as a valid antifungal target. Using a strain with doxycycline-repressible transcription of DFR1 (PTETO-DFR1 strain), we were able to demonstrate that Dfr1p is essential for growth in vitro. Furthermore, nutritional supplements of most forms of folate are not sufficient to restore growth when Dfr1p expression is suppressed or when its activity is directly inhibited by methotrexate, indicating that Candida albicans has a limited capacity to acquire or utilize exogenous sources of folate. Finally, the PTETO-DFR1 strain was rendered avirulent in a mouse model of disseminated candidiasis upon doxycycline treatment. Collectively, these results confirm the validity of targeting dihydrofolate reductase and, by inference, other enzymes in the folate biosynthetic pathway as a strategy to devise new and efficacious therapies to combat life-threatening invasive fungal infections. IMPORTANCE The folate biosynthetic pathway is a promising and understudied source for novel antifungals. Even dihydrofolate reductase (DHFR), a well-characterized and historically important drug target, has not been conclusively validated as an antifungal target. Here, we demonstrate that repression of DHFR inhibits growth of Candida albicans, a major human fungal pathogen. Methotrexate, an antifolate, also inhibits growth but through pH-dependent activity. In addition, we show that C. albicans has a limited ability to take up or utilize exogenous folates as only the addition of high concentrations of folinic acid restored growth in the presence of methotrexate. Finally, we show that repression of DHFR in a mouse model of infection was sufficient to eliminate host mortality. Our work conclusively establishes DHFR as a valid antifungal target in C. albicans.Christian DeJarnetteArturo Luna-TapiaLeanna R. EstredgeGlen E. PalmerAmerican Society for MicrobiologyarticleCandida albicansantifungal agentsdihydrofolate reductaseMicrobiologyQR1-502ENmSphere, Vol 5, Iss 3 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Candida albicans antifungal agents dihydrofolate reductase Microbiology QR1-502
spellingShingle	Candida albicans antifungal agents dihydrofolate reductase Microbiology QR1-502 Christian DeJarnette Arturo Luna-Tapia Leanna R. Estredge Glen E. Palmer Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
description	ABSTRACT While the folate biosynthetic pathway has provided a rich source of antibacterial, antiprotozoal, and anticancer therapies, it has not yet been exploited to develop uniquely antifungal agents. Although there have been attempts to develop fungal-specific inhibitors of dihydrofolate reductase (DHFR), the protein itself has not been unequivocally validated as essential for fungal growth or virulence. The purpose of this study was to establish dihydrofolate reductase as a valid antifungal target. Using a strain with doxycycline-repressible transcription of DFR1 (PTETO-DFR1 strain), we were able to demonstrate that Dfr1p is essential for growth in vitro. Furthermore, nutritional supplements of most forms of folate are not sufficient to restore growth when Dfr1p expression is suppressed or when its activity is directly inhibited by methotrexate, indicating that Candida albicans has a limited capacity to acquire or utilize exogenous sources of folate. Finally, the PTETO-DFR1 strain was rendered avirulent in a mouse model of disseminated candidiasis upon doxycycline treatment. Collectively, these results confirm the validity of targeting dihydrofolate reductase and, by inference, other enzymes in the folate biosynthetic pathway as a strategy to devise new and efficacious therapies to combat life-threatening invasive fungal infections. IMPORTANCE The folate biosynthetic pathway is a promising and understudied source for novel antifungals. Even dihydrofolate reductase (DHFR), a well-characterized and historically important drug target, has not been conclusively validated as an antifungal target. Here, we demonstrate that repression of DHFR inhibits growth of Candida albicans, a major human fungal pathogen. Methotrexate, an antifolate, also inhibits growth but through pH-dependent activity. In addition, we show that C. albicans has a limited ability to take up or utilize exogenous folates as only the addition of high concentrations of folinic acid restored growth in the presence of methotrexate. Finally, we show that repression of DHFR in a mouse model of infection was sufficient to eliminate host mortality. Our work conclusively establishes DHFR as a valid antifungal target in C. albicans.
format	article
author	Christian DeJarnette Arturo Luna-Tapia Leanna R. Estredge Glen E. Palmer
author_facet	Christian DeJarnette Arturo Luna-Tapia Leanna R. Estredge Glen E. Palmer
author_sort	Christian DeJarnette
title	Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
title_short	Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
title_full	Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
title_fullStr	Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
title_full_unstemmed	Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>
title_sort	dihydrofolate reductase is a valid target for antifungal development in the human pathogen <italic toggle="yes">candida albicans</italic>
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/7bedfb15049f4488a03cf31477b69091
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Dihydrofolate Reductase Is a Valid Target for Antifungal Development in the Human Pathogen <italic toggle="yes">Candida albicans</italic>

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