Benign yeast turn into filamentous pathogens in different ways
The yeast Candida albicans lives on and even inside many of us. Most of the time, its silent presence goes unnoticed, but this fungus can turn on its host, causing infections ranging in severity from annoying to life-threatening. For the yeast to become pathogenic, some of the C. albicans must transform from small, round cells into long, thread-like filaments, a process that can be triggered by environmental cues. To learn more about how these yeast morph, Azadmanesh et al. examined C. albicans filamentation under ten different conditions—and their results may have implications for the ways we study and treat infections.
C. albicans filamentation can be triggered by a variety of stimuli, from the surface the yeast are growing on to chemicals floating around them. Acidic environments, for example, make filamentation less likely, which is thought to be one reason maintaining a healthy balance of lactic acid-generating bacteria helps prevent vaginal yeast infections. Azadmanesh et al. determined which genes are required for filamentation under ten different environmental conditions, and for each condition, they also examined how gene expression changes during filamentation.
The researchers identified several genes needed for filamentation in all the conditions tested. In most cases, the reasons these genes are needed isn’t clear, but some have roles that make sense given what we know about how filamentation works. A few of the genes, for example, are involved in regulating the actin cytoskeleton, and modifications to the actin cytoskeleton are required for filamentation.
Surprisingly, though, the core genes required for filamentation under all conditions are the exceptions. Mostly, they found that both the genetic requirements for filamentation and the gene expression changes vary significantly in different conditions. This means that when researchers are comparing previous studies of C. albicans filamentation, they may not be comparing two like things: the programs of filamentation may be different in each case. The group’s work also has medical implications. The genes required for filamentation are different in solid and liquid media, suggesting that C. albicans infections in the gastrointestinal and genitourinary tracts are likely different from those found in bodily fluids like blood—which may be an important factor to consider when studying these infections and designing treatments.
Azadmanesh, J.; Gowen, A.; Creger, P.; Schafer, N.; Blankenship, J. Filamentation Involves Two Overlapping, but Distinct, Programs of Filamentation in the Pathogenic Fungus Candida albicans.
G3, 7(11), 3797-3808.