Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>

ABSTRACT Melanin is an antioxidant polyphenol pigment required for the pathogenicity of many fungal pathogens, but comprehensive regulatory mechanisms remain unidentified. In this study, we systematically analyzed melanin-regulating signaling pathways in Cryptococcus neoformans and identified four m...

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Autores principales:	Dongpil Lee, Eun-Ha Jang, Minjae Lee, Sun-Woo Kim, Yeonseon Lee, Kyung-Tae Lee, Yong-Sun Bahn
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	Bzp4 Usv101 Mbs1 Hob1 Gsk3 TOR pathway Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/bfe270c5cc794942af086169176b8883
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spelling	oai:doaj.org-article:bfe270c5cc794942af086169176b88832021-11-15T15:59:41ZUnraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>10.1128/mBio.02267-192150-7511https://doaj.org/article/bfe270c5cc794942af086169176b88832019-10-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02267-19https://doaj.org/toc/2150-7511ABSTRACT Melanin is an antioxidant polyphenol pigment required for the pathogenicity of many fungal pathogens, but comprehensive regulatory mechanisms remain unidentified. In this study, we systematically analyzed melanin-regulating signaling pathways in Cryptococcus neoformans and identified four melanin-regulating core transcription factors (TFs), Bzp4, Usv101, Mbs1, and Hob1, required for induction of the laccase gene (LAC1). Bzp4, Usv101, and Mbs1 independently regulate LAC1 induction, whereas Hob1 controls Bzp4 and Usv101 expression. Both Bzp4 and Usv101 are localized in the cytoplasm under nutrient-rich conditions (i.e., in the presence of yeast extract-peptone-dextrose [YPD] medium) but translocate into the nucleus upon nutrient starvation (i.e., in the presence of yeast nitrogen base [YNB] medium without glucose), and Mbs1 is constitutively localized in the nucleus. Notably, the cAMP pathway is not involved in regulation of the four TFs, but the high-osmolarity glycerol response (HOG) pathway negatively regulates induction of BZP4 and LAC1. Next, we searched for potential kinases upstream of the core TFs and identified nine core kinases; their deletion led to defective melanin production and LAC1 induction. Deletion of GSK3 or KIC1 abolished induction of LAC1 and BZP4 and perturbed nuclear translocation of Bzp4. Notably, Gsk3 also regulated expression of HOB1, USV101, and MBS1, indicating that it is a critical melanin-regulating kinase. Finally, an RNA sequencing-based transcriptome analysis of the wild-type strain and of bzp4Δ, usv101Δ, hob1Δ, and mbs1Δ strains under nutrient-rich and nutrient-starved conditions revealed that the melanin-regulating core TFs govern redundant and distinct classes of genes involved in a variety of biological processes. IMPORTANCE Melanins are dark green, brown, or black pigments that serve as antioxidant, reactive oxygen species (ROS) scavengers that protect fungal pathogens from radiation and host immune responses. Cryptococcus neoformans, the major etiological agent of fungal meningoencephalitis, also utilizes melanin as a key virulence factor. In this basidiomycete pathogen, melanin production is regulated by the cAMP and high-osmolarity glycerol response (HOG) pathways, and yet its complex signaling networks remain poorly described. In this study, we uncovered novel melanin synthesis regulatory networks consisting of core transcription factors (TFs), including Bzp4, Usv101, Hob1, and Mbs1, and core kinases Gsk3 and Kic1. These networks were identified through coupling systematic analyses of the expression and epistatic relationships of TF and kinase mutant libraries in the presence of diverse melanin substrates with transcriptome profiling of the core TF mutants. Thus, this report provides comprehensive insight into the melanin-regulating pathways in C. neoformans and other fungal pathogens.Dongpil LeeEun-Ha JangMinjae LeeSun-Woo KimYeonseon LeeKyung-Tae LeeYong-Sun BahnAmerican Society for MicrobiologyarticleBzp4Usv101Mbs1Hob1Gsk3TOR pathwayMicrobiologyQR1-502ENmBio, Vol 10, Iss 5 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	Bzp4 Usv101 Mbs1 Hob1 Gsk3 TOR pathway Microbiology QR1-502
spellingShingle	Bzp4 Usv101 Mbs1 Hob1 Gsk3 TOR pathway Microbiology QR1-502 Dongpil Lee Eun-Ha Jang Minjae Lee Sun-Woo Kim Yeonseon Lee Kyung-Tae Lee Yong-Sun Bahn Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
description	ABSTRACT Melanin is an antioxidant polyphenol pigment required for the pathogenicity of many fungal pathogens, but comprehensive regulatory mechanisms remain unidentified. In this study, we systematically analyzed melanin-regulating signaling pathways in Cryptococcus neoformans and identified four melanin-regulating core transcription factors (TFs), Bzp4, Usv101, Mbs1, and Hob1, required for induction of the laccase gene (LAC1). Bzp4, Usv101, and Mbs1 independently regulate LAC1 induction, whereas Hob1 controls Bzp4 and Usv101 expression. Both Bzp4 and Usv101 are localized in the cytoplasm under nutrient-rich conditions (i.e., in the presence of yeast extract-peptone-dextrose [YPD] medium) but translocate into the nucleus upon nutrient starvation (i.e., in the presence of yeast nitrogen base [YNB] medium without glucose), and Mbs1 is constitutively localized in the nucleus. Notably, the cAMP pathway is not involved in regulation of the four TFs, but the high-osmolarity glycerol response (HOG) pathway negatively regulates induction of BZP4 and LAC1. Next, we searched for potential kinases upstream of the core TFs and identified nine core kinases; their deletion led to defective melanin production and LAC1 induction. Deletion of GSK3 or KIC1 abolished induction of LAC1 and BZP4 and perturbed nuclear translocation of Bzp4. Notably, Gsk3 also regulated expression of HOB1, USV101, and MBS1, indicating that it is a critical melanin-regulating kinase. Finally, an RNA sequencing-based transcriptome analysis of the wild-type strain and of bzp4Δ, usv101Δ, hob1Δ, and mbs1Δ strains under nutrient-rich and nutrient-starved conditions revealed that the melanin-regulating core TFs govern redundant and distinct classes of genes involved in a variety of biological processes. IMPORTANCE Melanins are dark green, brown, or black pigments that serve as antioxidant, reactive oxygen species (ROS) scavengers that protect fungal pathogens from radiation and host immune responses. Cryptococcus neoformans, the major etiological agent of fungal meningoencephalitis, also utilizes melanin as a key virulence factor. In this basidiomycete pathogen, melanin production is regulated by the cAMP and high-osmolarity glycerol response (HOG) pathways, and yet its complex signaling networks remain poorly described. In this study, we uncovered novel melanin synthesis regulatory networks consisting of core transcription factors (TFs), including Bzp4, Usv101, Hob1, and Mbs1, and core kinases Gsk3 and Kic1. These networks were identified through coupling systematic analyses of the expression and epistatic relationships of TF and kinase mutant libraries in the presence of diverse melanin substrates with transcriptome profiling of the core TF mutants. Thus, this report provides comprehensive insight into the melanin-regulating pathways in C. neoformans and other fungal pathogens.
format	article
author	Dongpil Lee Eun-Ha Jang Minjae Lee Sun-Woo Kim Yeonseon Lee Kyung-Tae Lee Yong-Sun Bahn
author_facet	Dongpil Lee Eun-Ha Jang Minjae Lee Sun-Woo Kim Yeonseon Lee Kyung-Tae Lee Yong-Sun Bahn
author_sort	Dongpil Lee
title	Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
title_short	Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
title_full	Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
title_fullStr	Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
title_full_unstemmed	Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>
title_sort	unraveling melanin biosynthesis and signaling networks in <named-content content-type="genus-species">cryptococcus neoformans</named-content>
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/bfe270c5cc794942af086169176b8883
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Unraveling Melanin Biosynthesis and Signaling Networks in <named-content content-type="genus-species">Cryptococcus neoformans</named-content>

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