Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species

Pathogenic fungi that exhibit the ability to alternate between hyphal and yeast morphology in response to environmental stimuli are considered dimorphic. Under saprobic conditions, some fungi exist as filamentous hyphae, producing conidia. When conidia are inhaled by mammals or traumatically inocula...

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Main Authors: Uriel Ramírez-Sotelo, Manuela Gómez-Gaviria, Héctor M. Mora-Montes
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Pathogens
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Online Access:https://www.mdpi.com/2076-0817/14/4/350
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author Uriel Ramírez-Sotelo
Manuela Gómez-Gaviria
Héctor M. Mora-Montes
author_facet Uriel Ramírez-Sotelo
Manuela Gómez-Gaviria
Héctor M. Mora-Montes
author_sort Uriel Ramírez-Sotelo
collection DOAJ
description Pathogenic fungi that exhibit the ability to alternate between hyphal and yeast morphology in response to environmental stimuli are considered dimorphic. Under saprobic conditions, some fungi exist as filamentous hyphae, producing conidia. When conidia are inhaled by mammals or traumatically inoculated, body temperature (37 °C) triggers dimorphism into yeast cells. This shift promotes fungal dissemination and immune evasion. Some fungal pathogens undergo dimorphism in the contrary way, forming pseudohyphae and hyphae within the host. While temperature is a major driver of dimorphism, other factors, including CO<sub>2</sub> concentration, pH, nitrogen sources, and quorum-sensing molecules, also contribute to morphological shifts. This morphological transition is associated with increased expression of virulence factors that aid in adhesion, colonization, and immune evasion. <i>Candida albicans</i> is a fungus that is commonly found as a commensal on human mucous membranes but has the potential to be an opportunistic fungal pathogen of immunocompromised patients. <i>C. albicans</i> exhibits a dimorphic change from the yeast form to the hyphal form when it becomes established as a pathogen. In contrast, <i>Histoplasma capsulatum</i> is an environmental dimorphic fungus where human infection begins when conidia or hyphal fragments of the fungus are inhaled into the alveoli, where the dimorphic change to yeast occurs, this being the morphology associated with its pathogenic phase. This review examines the main signaling pathways that have been mostly related to fungal dimorphism, using as a basis the information available in the literature on <i>H. capsulatum</i> and <i>C. albicans</i> because these fungi have been widely studied for the morphological transition from hypha to yeast and from yeast to hypha, respectively. In addition, we have included the reported findings of these signaling pathways associated with the dimorphism of other pathogenic fungi, such as <i>Paracoccidioides brasiliensis</i>, <i>Sporothrix schenckii</i>, <i>Cryptococcus neoformans</i>, and <i>Blastomyces dermatitis</i>. Understanding these pathways is essential for advancing therapeutic approaches against systemic fungal infections.
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spelling doaj-art-235f58c584674aa8b28e2d2feb2d57dd2025-08-20T02:18:15ZengMDPI AGPathogens2076-08172025-04-0114435010.3390/pathogens14040350Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal SpeciesUriel Ramírez-Sotelo0Manuela Gómez-Gaviria1Héctor M. Mora-Montes2Departamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, Guanajuato C.P. 36050, MexicoDepartamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, Guanajuato C.P. 36050, MexicoDepartamento de Biología, División de Ciencias Naturales y Exactas, Campus Guanajuato, Universidad de Guanajuato, Noria Alta s/n, col. Noria Alta, Guanajuato C.P. 36050, MexicoPathogenic fungi that exhibit the ability to alternate between hyphal and yeast morphology in response to environmental stimuli are considered dimorphic. Under saprobic conditions, some fungi exist as filamentous hyphae, producing conidia. When conidia are inhaled by mammals or traumatically inoculated, body temperature (37 °C) triggers dimorphism into yeast cells. This shift promotes fungal dissemination and immune evasion. Some fungal pathogens undergo dimorphism in the contrary way, forming pseudohyphae and hyphae within the host. While temperature is a major driver of dimorphism, other factors, including CO<sub>2</sub> concentration, pH, nitrogen sources, and quorum-sensing molecules, also contribute to morphological shifts. This morphological transition is associated with increased expression of virulence factors that aid in adhesion, colonization, and immune evasion. <i>Candida albicans</i> is a fungus that is commonly found as a commensal on human mucous membranes but has the potential to be an opportunistic fungal pathogen of immunocompromised patients. <i>C. albicans</i> exhibits a dimorphic change from the yeast form to the hyphal form when it becomes established as a pathogen. In contrast, <i>Histoplasma capsulatum</i> is an environmental dimorphic fungus where human infection begins when conidia or hyphal fragments of the fungus are inhaled into the alveoli, where the dimorphic change to yeast occurs, this being the morphology associated with its pathogenic phase. This review examines the main signaling pathways that have been mostly related to fungal dimorphism, using as a basis the information available in the literature on <i>H. capsulatum</i> and <i>C. albicans</i> because these fungi have been widely studied for the morphological transition from hypha to yeast and from yeast to hypha, respectively. In addition, we have included the reported findings of these signaling pathways associated with the dimorphism of other pathogenic fungi, such as <i>Paracoccidioides brasiliensis</i>, <i>Sporothrix schenckii</i>, <i>Cryptococcus neoformans</i>, and <i>Blastomyces dermatitis</i>. Understanding these pathways is essential for advancing therapeutic approaches against systemic fungal infections.https://www.mdpi.com/2076-0817/14/4/350transcription factorenvironmental stimuliyeasthyphakinaseantifungal drug
spellingShingle Uriel Ramírez-Sotelo
Manuela Gómez-Gaviria
Héctor M. Mora-Montes
Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
Pathogens
transcription factor
environmental stimuli
yeast
hypha
kinase
antifungal drug
title Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
title_full Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
title_fullStr Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
title_full_unstemmed Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
title_short Signaling Pathways Regulating Dimorphism in Medically Relevant Fungal Species
title_sort signaling pathways regulating dimorphism in medically relevant fungal species
topic transcription factor
environmental stimuli
yeast
hypha
kinase
antifungal drug
url https://www.mdpi.com/2076-0817/14/4/350
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