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H3K36 Methylation Regulates Nutrient Stress Response in S. cerevisiae by Enforcing Transcriptional Fidelity

ABSTRACT: 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.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE89265 | GEO | 2017/06/05

SECONDARY ACCESSION(S): PRJNA350898

REPOSITORIES: GEO

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Project description:The target of rapamycin (TOR) pathway is an evolutionarily conserved signal transduction system that is activated by varying nutrient and environmental signals and governs a plethora of eukaryotic biological processes. Nevertheless, its role in the human fungal pathogen Cryptococcus neoformans remains elusive. In this study, we investigated the TOR pathway by functionally characterizing two Tor-like kinases, Tor1 and Tlk1, in C. neoformans. We successfully deleted TLK1, but not TOR1. TLK1 deletion did not result in any evident in vitro phenotypes, except for a minor role in diamide and polyene resistance, suggesting that Tlk1 is mainly dispensable for the growth of C. neoformans. We further demonstrated that Tor1, but not Tlk1, is essential and the target of rapamycin by constructing and analyzing conditionally regulated strains and sporulation analysis of heterozygous mutants in the diploid strain background. To analyze the functions of Tor1 in more detail, we constructed constitutive TOR1 overexpression strains. Tor1 negatively regulated thermotolerance and the DNA damage response, which are two important virulence factors of C. neoformans. We also found that TOR1 overexpression reduced Mpk1 phosphorylation, which is required for cell wall integrity and thermoresistance, and Rad53 phosphorylation, which governs the DNA damage response pathway. Tor1 is localized to the cytoplasm but enriched in the vacuole membrane. Phosphoproteomics and transcriptomics revealed that Tor1 regulates a variety of biological processes, including metabolic processes, cytoskeleton organization, ribosome biogenesis, autophagy, and stress response. Finally, screening rapamycin-sensitive and -resistant kinase and transcription factor mutants revealed that the TOR pathway may crosstalk with a number of signaling pathways, including the Hog1 pathway. In conclusion, our study demonstrates that a single Tor1 kinase plays a variety of roles in the fungal meningitis pathogen C. neoformans.

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H3K36 Methylation Regulates Nutrient Stress Response in S. cerevisiae by Enforcing Transcriptional Fidelity

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