Hog1 bypasses stress-mediated down-regulation of transcription by RNA polymerase II redistribution and chromatin remodeling

Abstract

BackgroundCells are subjected to dramatic changes of gene expression upon environmental changes. Stress causes a general down-regulation of gene expression together with the induction of a set of stress-responsive genes. The p38-related stress-activated protein kinase Hog1 is an important regulator of transcription upon osmostress in yeast.ResultsGenome-wide localization studies of RNA polymerase II (RNA Pol II) and Hog1 showed that stress induced major changes in RNA Pol II localization, with a shift toward stress-responsive genes relative to housekeeping genes. RNA Pol II relocalization required Hog1, which was also localized to stress-responsive loci. In addition to RNA Pol II-bound genes, Hog1 also localized to RNA polymerase III-bound genes, pointing to a wider role for Hog1 in transcriptional control than initially expected. Interestingly, an increasing association of Hog1 with stress-responsive genes was strongly correlated with chromatin remodeling and increased gene expression. Remarkably, MNase-Seq analysis showed that although chromatin structure was not significantly altered at a genome-wide level in response to stress, there was pronounced chromatin remodeling for those genes that displayed Hog1 association.ConclusionHog1 serves to bypass the general down-regulation of gene expression that occurs in response to osmostress, and does so both by targeting RNA Pol II machinery and by inducing chromatin remodeling at stress-responsive loci.

Hog1 Targets Whi5 and Msa1 Transcription Factors To Downregulate Cyclin Expression upon Stress

“…Hog1 itself associates with stress-responsive loci upon activation to induce gene expression (49,51,52). We therefore assessed the association of Hog1 with the CLN2 and CLB5 promoters.…”

“…Wild-type cells were incubated for 10 min in the presence or absence (control) of 0.4 M NaCl (D), or sln1 ts mutant cells were incubated at a nonpermissive temperature (37°C) for 30 min (E). HA-tagged Hog1 was used for chromatin immunoprecipitation in ChIP assays to monitor its association with the CLN2 and CLB5 promoters as described previously (49). Bars represent the averages Ϯ the standard deviations from three independent experiments.…”

“…Hog1 is a key player in the regulation of gene expression upon osmostress, causing a rapid and transient upregulation of osmoresponsive genes. However, Hog1 also mediates the transcriptional downregulation of specific genes in addition to those globally downregulated by stress (49). For instance, the G 1 cyclins are strongly downregulated by Hog1 in response to osmostress and this downregulation is important for cell cycle control (36,39,41).…”

Initiation of the transcriptional response to hyperosmotic shock correlates with the potential for volume recovery

“…Thus, a few minute differences might be sufficient to account for full chromatin remodelling and transcription. If a certain threshold is not accomplished then the transcriptional outcome is clearly impaired [16,20].…”

Global Epitranscriptomics Profiling of RNA Post-Transcriptional Modifications as an Effective Tool for Investigating the Epitranscriptomics of Stress Response

“…For this reason, we first compared PTM profiles obtained from wildtype S. cerevisiae (i.e. WT) in the absence and presence of osmostress to identify possible PTM variations that correlated with the known induction of stress-response coding and noncoding genes (43). Then, we performed the profiling of a mutant strain in which the HOG1 gene was deleted (i.e.…”