A MAP kinase pathway is implicated in the pseudohyphal induction by Hydrogen peroxide in candica albicans

Abstract

Hydrogen peroxide (H2O2) functions as a ubiquitous intracellular messenger besides as an oxidative stress molecule. This dual role is based on the distinct cellular responses against different concentrations of H2O2. Previously, we demonstrated that both low (> 1 mM) and high (4-10 mM) doses of exogenous H2O2 induce filamentous growth with distinct cell morphology and growth rate in Candida albicans, suggesting the different transcription response. In this study, we revealed that the sub-toxic and toxic levels of H2O2 indeed induced pseudohyphae, but not true hyphae. Supporting this, several hyphae-specific genes that are expressed in true hyphae induced by serum were not detected in either sub-toxic or toxic H2O2 condition. A DNA microarray analysis was conducted to reveal the transcription profiles in cells treated with sub-toxic and toxic conditions of H2O2. Under the sub-toxic condition, a small number of genes involved in cell proliferation and metabolism were up-regulated, whereas a large number of genes were up-regulated in the toxic condition where the genes required for growth and proliferation were selectively restricted. For pseudohyphal induction by sub-toxic H2O2, Cek1 MAPK activating the transcription factor Cph1 was shown to be important. The absence of expression of several hyphae-specific genes known to be downstream targets of Cph1-signaling pathway for true hyphae formation suggests that the Cek1-mediated signaling pathway is not solely responsible for pseudohyphal formation by subtoxic H 2O2 and, but instead, complex networking pathway may exists by the activation of different regulators. © 2012 KSMCB.