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Transcriptional control of dimorphism in Candida albicans
1Department of Biological Chemistry, 19172 Jamboree Road, University of California at Irvine, Irvine, CA 92697-1700, USA. H4LIU@UCI.EDU
Abstract:
Candida albicans uses a network of multiple signaling pathways to control the yeast-->hypha transition. These include a mitogen-activated protein kinase pathway through Cph1, the cAMP-dependent protein kinase pathway via Efg1, a pH-responsive pathway through Rim101, the Tup1-mediated repression through Rfg1 and Nrg1, and pathways represented by transcription factors Cph2, Tec1 and Czf1. These pathways control the transcription of a common set of hypha-specific genes, many of which encode known virulence factors. The link between the signaling pathways and hyphal elongation is currently unknown, but there is evidence to suggest that Cdc42 likely plays a key role in hyphal morphogenesis. Unlike pseudohyphal growth in Saccharomyces cerevisiae, hyphal elongation is regulated independently of the cell cycle. Cellular differences between pseudohyphae and hyphae are further revealed by septin localization.
Insights
Candida albicans hyphal development involves multiple signaling pathways controlling virulence factors. Cdc42 is key in hyphal morphogenesis, independent of the cell cycle.
Area of Science:
- Microbiology
- Molecular Biology
- Cell Biology
Background:
- Candida albicans transitions between yeast and hyphal forms, a critical step in pathogenesis.
- Multiple signaling pathways regulate this morphological switch, influencing virulence factor expression.
Purpose of the Study:
- To elucidate the complex network of signaling pathways governing the yeast-to-hypha transition in Candida albicans.
- To identify key regulators of hyphal elongation and morphogenesis.
Main Methods:
- Analysis of signaling pathways including MAPK (Cph1), PKA (Efg1), pH-responsive (Rim101), and Tup1-mediated repression (Rfg1, Nrg1).
- Investigation of transcription factors (Cph2, Tec1, Czf1) and their role in hypha-specific gene expression.
- Exploration of Cdc42's involvement in hyphal morphogenesis and cell cycle independence.
Main Results:
- Several signaling pathways converge to control hypha-specific genes, many encoding virulence factors.
- Cdc42 is implicated as a crucial mediator of hyphal morphogenesis.
- Hyphal elongation is regulated independently of the cell cycle, distinguishing it from pseudohyphal growth.
Conclusions:
- The yeast-to-hypha transition in C. albicans is orchestrated by a complex interplay of signaling pathways.
- Cdc42 plays a pivotal role in hyphal development, with implications for fungal virulence.
- Understanding these pathways offers targets for antifungal strategies.