Project description:Epigenetic mechanisms including histone post-translational modifications control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging aspect of shortened lifespan, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a lifespan screen in S. cerevisiae, designed to identify altered amino acid residues of histones that alter yeast replicative aging. Our results reveal that lack of sustained H3K36 methylation is commensurate with increased cryptic transcription in a set of genes in old cells and shorter lifespan. Deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes and suppresses cryptic transcript initiation to extend lifespan. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to an increase in transcriptional noise that is detrimental to lifespan, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity.
Project description:Epigenetic mechanisms including histone post-translational modifications control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging aspect of shortened lifespan, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a lifespan screen in S. cerevisiae, designed to identify altered amino acid residues of histones that alter yeast replicative aging. Our results reveal that lack of sustained H3K36 methylation is commensurate with increased cryptic transcription in a set of genes in old cells and shorter lifespan. Deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes and suppresses cryptic transcript initiation to extend lifespan. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to an increase in transcriptional noise that is detrimental to lifespan, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity.
Project description:Epigenetic mechanisms including histone post-translational modifications control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging aspect of shortened lifespan, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a lifespan screen in S. cerevisiae, designed to identify altered amino acid residues of histones that alter yeast replicative aging. Our results reveal that lack of sustained H3K36 methylation is commensurate with increased cryptic transcription in a set of genes in old cells and shorter lifespan. Deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes and suppresses cryptic transcript initiation to extend lifespan. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to an increase in transcriptional noise that is detrimental to lifespan, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity.
Project description:Epigenetic mechanisms, including histone post-translational modifications, control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging phenomenon of shortened life span, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a life span screen in Saccharomyces cerevisiae that is designed to identify amino acid residues of histones that regulate yeast replicative aging. Our results reveal that lack of sustained histone H3K36 methylation is commensurate with increased cryptic transcription in a subset of genes in old cells and with shorter life span. In contrast, deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes, suppresses cryptic transcript initiation, and extends life span. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to loss of transcriptional precision that is detrimental to life span, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity.
Project description:To study the function of this residue independent from the enzymes that modify it, we used a “histone replacement” system in Drosophila to generate a non-modifiable H3K36 lysine-to-arginine (H3K36R) mutant. Post-translational modification of histone H3K36 is neither required to suppress cryptic transcription initiation nor to include alternative exons in Drosophila; instead it promotes expression of active genes by stimulating polyadenylation.
Project description:Set2-mediated methylation of H3K36 (H3K36me) regulates a diverse number of activities including DNA repair, mRNA splicing and the suppression of inappropriate or ‘cryptic’ transcription. Here, we describe an unexpected connection between Set2-mediated H3K36me and the regulation of nutrient stress response. We find cells deleted for SET2 (set2∆) are sensitive to inhibitors of Tor1, Tor2 and MAP kinase pathways that regulate the nutrient response pathway. Further genetic and biochemical analyses confirm a role for Set2-mediated H3K36me in nutrient stress response. At the molecular level, set2∆ cells demonstrate a dysregulated genome-wide transcriptional response to nutrient stress. Remarkably, newly initiated and bi-directional transcription events within the bodies of genes develop in set2∆ cells during nutrient stress. Importantly, these antisense transcripts extend into the promoters of the genes they arise from, resulting in pervasive transcriptional interference. Our results suggest that Set2-enforced transcriptional fidelity is critical to the proper regulation highly-tuned transcription programs.