The transcriptional response of yeast to saline stress

Adaptation to changes in extracellular salinity is a critical event for cel l survival. Genome-wide DNA chip analysis has been used to analyze the tran scriptional response of yeast cells to saline stress. About 7% of the genes encoded in the yeast genome are induced more than 5-fold after a mild and brief saline shock (0.4 M NaCl, 10 min). Interestingly, most responsive gen es showed a very transient expression pattern, as mRNA levels dramatically declined after 20 min in the presence of stress. A quite similar set of gen es increased expression in cells subjected to higher saline concentrations (0.8 M NaCl), although in this case the response was delayed. Therefore, ou r data show that cells respond to saline stress by inducing the expression of a very large number of genes and suggest that stress adaptation requires regulation of many cellular aspects. The transcriptional induction of most genes that are strongly responsive to salt stress was highly or fully depe ndent on the presence of the stress-activated mitogen-activated protein kin ase Hog1, indicating that the Hog1-mediated signaling pathway plays a key r ole in global gene regulation under saline stress conditions.