H3K4 monomethylation dictates nucleosome dynamics and chromatin remodeling at stress-responsive genes.
Bottom Line: The p38-related Hog1 SAPK is an important regulator of transcription that mediates chromatin remodeling upon stress.Monomethylation of H3K4 is specifically inhibiting RSC-independent chromatin remodeling and thus, it prevents osmostress-induced gene expression.Our findings point to a novel role for H3K4 monomethylation in dictating the specificity of chromatin remodeling, adding an extra layer of regulation to the transcriptional stress response.
Affiliation: Cell signaling unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain.Show MeSH
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Mentions: Since lack of H3K4 methylation suppressed the RSC deficiency and permitted nucleosome remodeling in response to stress, we hypothesized that an alternative remodeler might act at stress-responsive genes in the absence of H3K4 methylation. To identify such a chromatin remodeler(s), we performed a targeted candidate screen in which we deleted genes encoding representative members of all chromatin remodeling complexes in yeast (a total of 20 were assayed), in the set1 rsc9ts background. We reasoned that in the absence of this alternative remodeler the set1 deficiency should not suppress the rsc9ts mutation. When monitoring gene expression in these mutant strains, we found that only the absence of BDF1 in that background rendered cells that were unable to induce gene (STL1 and CTT1 in lesser extend) expression upon stress (Figures 5A and 6A). We then tested whether Bdf1 was recruited to stress-responsive genes upon osmostress, using ChIP assays. Although Bdf1 indeed associates with STL1 upon stress in wild type, set1Δ and rsc9ts strains, its binding was more robust in set1 rsc9ts deficient cells (Figure 5B). Of note, we did not detect differences in Bdf1 recruitment when comparing wild type, set1Δ, rsc9ts and set1Δ rsc9ts mutant strains in the absence of stress (Supplementary Figure S5).
Affiliation: Cell signaling unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra (UPF), Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain.