Morphogenesis in C. albicans

Abstract

Many human fungal pathogens possess the ability to grow in a variety of different morphologies and Candida albicans is no exception. In dimorphic fungal pathogens, such as Histoplasma capsulatum and Coccidioides immitis, morphological transitions are critical for virulence (Klein and Tebbets, Curr Opin Microbiol, 10(4):314-319, 2007). However, other pathogens, such as Candida glabrata, rarely alter their morphology and the ability to change shape appears to play little, if any, role in their pathogenicity (Do Carmo-Sousa 1969; Fidel et al., Clin Microbiol Rev 12:80-96, 1999; Csank and Haynes, FEMS Microbiol Lett 189(1):115-120, 2000). The ability of Candida albicans to undergo a reversible morphological transition from yeast to filamentous form represents a fundamental aspect of this pathogen's biology. This transition is typically correlated with pathogenicity and important for a wide variety of virulence-related processes (Lo et al., Cell 90(5):939-949, 1997; Braun and Johnson, Science 277(5322):105-109, 1997; Braun et al., Genetics 156 (1):31-44, 2000; Saville et al., Eukaryot Cell 2(5):1053-1060, 2003; Carlisle et al., Proc Natl Acad Sci USA 106:599-604, 2009; Kumamoto and Vinces, Proc Natl Acad Sci USA 102(15):5576-5581, 2005; Korting et al., J Med Microbiol 52(Pt 8):623-632, 2003; Gow et al., Curr opin microbiol 5(4):366-371, 2002). As a consequence, a significant amount of research, mostly over the past 25 years, has focused on signaling pathways, regulators, and mechanisms that are involved in controlling the C. albicans morphological transition. In this chapter we will first describe the major C. albicans morphologies and the relationship between C. albicans morphology and virulence. Next, we will discuss the mechanics of hyphal growth as well as a variety of signaling pathways, regulators, and mechanisms important for regulating C. albicans morphogenesis in response to host environmental cues. Finally, we will discuss recent insights gained from genome-wide studies of the C. albicans morphological transition as well as the potential that this transition may hold to serve as a target for new therapeutic strategies.