Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH

ABSTRACT Phosphate acquisition by fungi is regulated by the phosphate-sensing and acquisition (PHO) signaling pathway. Cryptococcus neoformans disseminates from the lung to the brain and is the commonest cause of fungal meningitis worldwide. To investigate the contribution of PHO signaling to crypto...

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Autores principales:	Sophie Lev, Keren Kaufman-Francis, Desmarini Desmarini, Pierre G. Juillard, Cecilia Li, Sebastian A. Stifter, Carl G. Feng, Tania C. Sorrell, Georges E. R. Grau, Yong-Sun Bahn, Julianne T. Djordjevic
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	cryptococcal meningitis cryptococcoma Cryptococcus neoformans fungal pathogenesis HLH-type transcription factor intravenous inoculation Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/e6ebd73772e44c50ab5233ebc0ecbd4b
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spelling	oai:doaj.org-article:e6ebd73772e44c50ab5233ebc0ecbd4b2021-11-15T15:22:03ZPho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH10.1128/mSphere.00381-162379-5042https://doaj.org/article/e6ebd73772e44c50ab5233ebc0ecbd4b2017-02-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00381-16https://doaj.org/toc/2379-5042ABSTRACT Phosphate acquisition by fungi is regulated by the phosphate-sensing and acquisition (PHO) signaling pathway. Cryptococcus neoformans disseminates from the lung to the brain and is the commonest cause of fungal meningitis worldwide. To investigate the contribution of PHO signaling to cryptococcal dissemination, we characterized a transcription factor knockout strain (hlh3Δ/pho4Δ) defective in phosphate acquisition. Despite little similarity with other fungal Pho4 proteins, Hlh3/Pho4 functioned like a typical phosphate-responsive transcription factor in phosphate-deprived cryptococci, accumulating in nuclei and triggering expression of genes involved in phosphate acquisition. The pho4Δ mutant strain was susceptible to a number of stresses, the effect of which, except for alkaline pH, was alleviated by phosphate supplementation. Even in the presence of phosphate, the PHO pathway was activated in wild-type cryptococci at or above physiological pH, and under these conditions, the pho4Δ mutant had a growth defect and compromised phosphate uptake. The pho4Δ mutant was hypovirulent in a mouse inhalation model, where dissemination to the brain was reduced dramatically, and markedly hypovirulent in an intravenous dissemination model. The pho4Δ mutant was not detected in blood, nor did it proliferate significantly when cultured with peripheral blood monocytes. In conclusion, dissemination of infection and the pathogenesis of meningitis are dependent on cryptococcal phosphate uptake and stress tolerance at alkaline pH, both of which are Pho4 dependent. IMPORTANCE Cryptococcal meningitis is fatal without treatment and responsible for more than 500,000 deaths annually. To be a successful pathogen, C. neoformans must obtain an adequate supply of essential nutrients, including phosphate, from various host niches. Phosphate acquisition in fungi is regulated by the PHO signaling cascade, which is activated when intracellular phosphate decreases below a critical level. Induction of phosphate acquisition genes leads to the uptake of free phosphate via transporters. By blocking the PHO pathway using a Pho4 transcription factor mutant (pho4Δ mutant), we demonstrate the importance of the pathway for cryptococcal dissemination and the establishment of brain infection in murine models. Specifically, we show that reduced dissemination of the pho4Δ mutant to the brain is due to an alkaline pH tolerance defect, as alkaline pH mimics the conditions of phosphate deprivation. The end result is inhibited proliferation in host tissues, particularly in blood. Podcast: A podcast concerning this article is available.Sophie LevKeren Kaufman-FrancisDesmarini DesmariniPierre G. JuillardCecilia LiSebastian A. StifterCarl G. FengTania C. SorrellGeorges E. R. GrauYong-Sun BahnJulianne T. DjordjevicAmerican Society for Microbiologyarticlecryptococcal meningitiscryptococcomaCryptococcus neoformansfungal pathogenesisHLH-type transcription factorintravenous inoculationMicrobiologyQR1-502ENmSphere, Vol 2, Iss 1 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	cryptococcal meningitis cryptococcoma Cryptococcus neoformans fungal pathogenesis HLH-type transcription factor intravenous inoculation Microbiology QR1-502
spellingShingle	cryptococcal meningitis cryptococcoma Cryptococcus neoformans fungal pathogenesis HLH-type transcription factor intravenous inoculation Microbiology QR1-502 Sophie Lev Keren Kaufman-Francis Desmarini Desmarini Pierre G. Juillard Cecilia Li Sebastian A. Stifter Carl G. Feng Tania C. Sorrell Georges E. R. Grau Yong-Sun Bahn Julianne T. Djordjevic Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
description	ABSTRACT Phosphate acquisition by fungi is regulated by the phosphate-sensing and acquisition (PHO) signaling pathway. Cryptococcus neoformans disseminates from the lung to the brain and is the commonest cause of fungal meningitis worldwide. To investigate the contribution of PHO signaling to cryptococcal dissemination, we characterized a transcription factor knockout strain (hlh3Δ/pho4Δ) defective in phosphate acquisition. Despite little similarity with other fungal Pho4 proteins, Hlh3/Pho4 functioned like a typical phosphate-responsive transcription factor in phosphate-deprived cryptococci, accumulating in nuclei and triggering expression of genes involved in phosphate acquisition. The pho4Δ mutant strain was susceptible to a number of stresses, the effect of which, except for alkaline pH, was alleviated by phosphate supplementation. Even in the presence of phosphate, the PHO pathway was activated in wild-type cryptococci at or above physiological pH, and under these conditions, the pho4Δ mutant had a growth defect and compromised phosphate uptake. The pho4Δ mutant was hypovirulent in a mouse inhalation model, where dissemination to the brain was reduced dramatically, and markedly hypovirulent in an intravenous dissemination model. The pho4Δ mutant was not detected in blood, nor did it proliferate significantly when cultured with peripheral blood monocytes. In conclusion, dissemination of infection and the pathogenesis of meningitis are dependent on cryptococcal phosphate uptake and stress tolerance at alkaline pH, both of which are Pho4 dependent. IMPORTANCE Cryptococcal meningitis is fatal without treatment and responsible for more than 500,000 deaths annually. To be a successful pathogen, C. neoformans must obtain an adequate supply of essential nutrients, including phosphate, from various host niches. Phosphate acquisition in fungi is regulated by the PHO signaling cascade, which is activated when intracellular phosphate decreases below a critical level. Induction of phosphate acquisition genes leads to the uptake of free phosphate via transporters. By blocking the PHO pathway using a Pho4 transcription factor mutant (pho4Δ mutant), we demonstrate the importance of the pathway for cryptococcal dissemination and the establishment of brain infection in murine models. Specifically, we show that reduced dissemination of the pho4Δ mutant to the brain is due to an alkaline pH tolerance defect, as alkaline pH mimics the conditions of phosphate deprivation. The end result is inhibited proliferation in host tissues, particularly in blood. Podcast: A podcast concerning this article is available.
format	article
author	Sophie Lev Keren Kaufman-Francis Desmarini Desmarini Pierre G. Juillard Cecilia Li Sebastian A. Stifter Carl G. Feng Tania C. Sorrell Georges E. R. Grau Yong-Sun Bahn Julianne T. Djordjevic
author_facet	Sophie Lev Keren Kaufman-Francis Desmarini Desmarini Pierre G. Juillard Cecilia Li Sebastian A. Stifter Carl G. Feng Tania C. Sorrell Georges E. R. Grau Yong-Sun Bahn Julianne T. Djordjevic
author_sort	Sophie Lev
title	Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
title_short	Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
title_full	Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
title_fullStr	Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
title_full_unstemmed	Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH
title_sort	pho4 is essential for dissemination of <named-content content-type="genus-species">cryptococcus neoformans</named-content> to the host brain by promoting phosphate uptake and growth at alkaline ph
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/e6ebd73772e44c50ab5233ebc0ecbd4b
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Pho4 Is Essential for Dissemination of <named-content content-type="genus-species">Cryptococcus neoformans</named-content> to the Host Brain by Promoting Phosphate Uptake and Growth at Alkaline pH

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