Abstract:

In order to maintain homeostasis, cells have a series of complex mechanisms to sense alterations in their environment and adapt accordingly. Part of the regulation of stress responses occur at the level of transcription. The transcription factor Yap1p is a major regulator of the response to oxidative stress in Saccharomyces cerevisiae. Whole-genome microarray technology was used to compare the dynamics of the response to oxidative stress induced by cumene hydroperoxide (CHP) in a S. cerevisiae YAP1 knockout mutant with the response exhibited by its corresponding genetic background strain (wild-type strain). The response to CHP-induced stress at the transcriptome level was followed from 3 to 20 min after the addition of the oxidant. Differential analysis of gene expression allowed the identification of several genes and pathways that are differentially expresssed. Over 1000 genes seem to be regulated by Yap1p in response to oxidative stress, while a similar number of genes respond to oxidative stress even in its the absence. Interestingly, some genes seem to be regulated by Yap1p even in normal growth conditions, i.e. without oxidant stimulus. We also identified a set of 1200 genes that have their transcription levels changed only in the yap1(-/-) mutant under oxidative stress, suggesting possible alternative routes to the stress response when one of its main regulators is absent.  The differential regulation of genes studied in this work gives a significant insight on the current knowledge about the Yap1p transcriptional network, and creates new hypotheses about gene function and transcriptional regulation in yeast.