Expression levels of a filament-specific transcriptional regulator are sufficient to determine Candida albicans morphology and virulence

Patricia L. Carlisle, Mohua Banerjee, Anna Lazzell, Carlos Monteagudo, José L. López-Ribot, David Kadosh

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174 Scopus citations


Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphal and hyphal filaments (elongated cells attached end-to-end). Because typical C. albicans infections contain a mixture of these morphologies it has, for many years, been difficult to assess the relative contribution of each form to virulence. In addition, the regulatory mechanisms that determine growth in pseudohyphal and hyphal morphologies are largely unknown. To address these questions we have generated a C. albicans strain that can be genetically manipulated to grow completely in the hyphal form under non-filament-inducing conditions in vitro. This was achieved by inducing high-level constitutive expression of UME6, a recently identified filament-specific transcriptional regulator of C. albicans hyphal extension. We show that high-level UME6 expression significantly increases hyphal formation and promotes virulence in a mouse model of systemic candidiasis. Our results strongly suggest that shifting the morphology of a C. albicans population toward the hyphal form, and/or increasing hyphal-specific gene expression, during the course of infection is sufficient to improve virulence potential. We also demonstrate that lower levels of UME6 expression specify growth largely in the pseudohyphal form and that increasing UME6 levels is sufficient to cause cells to gradually shift from pseudohyphal to hyphal morphology. In addition, we show that UME6 levels differentially induce the expression of several known filament-specific transcripts. These findings suggest that a common transcriptional regulatory mechanism functions to specify both pseudohyphal and hyphal morphologies in a dosage-dependent manner.

Original languageEnglish (US)
Pages (from-to)599-604
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number2
StatePublished - Jan 13 2009


  • Filamentous growth
  • Transcriptional regulation

ASJC Scopus subject areas

  • General


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