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

Mariona Nadal-Ribelles,Eduardo Eyras,Eulàlia De Nadal,Modesto Orozco,Francesc Posas,Núria Conde,Juan González-Vallinas,Oscar Flores

doi:10.1186/gb-2012-13-11-r106

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.

Highlights

Cells are subjected to dramatic changes of gene expression upon environmental changes
When the presence of Hog1 was analyzed on RNA Pol II transcribed genes, we found that Hog1 was associated with approximately 80% of genes, with expression described to be highly dependent on the stressactivated protein kinase (SAPK), confirming that Hog1 is widely associated with Hog1-regulated genes
In response to an environmental insult such as osmostress, there are major changes of RNA Pol II localization towards stress-responsive genes, in contrast to housekeeping genes, which correlates with down-regulation of general transcription

Summary

Introduction

Cells are subjected to dramatic changes of gene expression upon environmental changes. The p38-related stress-activated protein kinase Hog is an important regulator of transcription upon osmostress in yeast. Yeast cells undergo major changes of gene expression in response to stress [1]. Major changes of gene expression occur in response to stress; many genes are down-regulated together with the up-regulation of a set of stress-responsive genes. Activation of the high osmolarity glycerol (HOG) pathway upon stress regulates many aspects of cell physiology, including gene expression. The p38-related Hog stressactivated protein kinase (SAPK) is the master protein for reprogramming gene expression in response to osmostress. We define a comprehensive picture of the genome-wide regulatory organization of the genome in response to stress and reveal Hog as the key protein needed to coordinate RNA Pol II relocalization, chromatin re-organization and osmospecific gene expression

Methods

Results

Conclusion