Project description:Purpose: The goals of this study were to determine whether the spliceosome interacts with non-intronic mRNAs Methods: RNAseq was performed on RNA that immunoprecipitated with the yeast SMD1 protein. Tandem-affinity-purified RNAs were extracted and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). We also performed RNAseq experiments on rRNA depleted total RNA extracted from an exosome mutant (rrp6M-NM-^T), a temperature-sensitive splicing mutant (prp40-1) and a parental strain (BY4741). The rRNA was depleted using the Invitrogen RiboMinus kit, according to manufactureres procedures. The depleted RNA was subsequently treated with Turbo DNAse I (Ambion) and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). Results: The SM RNAseq data identified a number of non-intronic mRNAs that appeard to be bound by the spliceosome. Among these was the BDF2 mRNA, which enocdes for a bromo-domain protein. BDF2 was highly enriched in both SM-IP datasets and was therefore analyzed in more detail. To determine if other non-intronic mRNAs could be regulated by the spliceosome, we analysed the transcriptome in the rrp6M-NM-^T, the prp40-1 and a parental strain. Bioinformatic analysis of these data sets revealed that roughly 1% of the non-intronic mRNAs in yeast could be targeted by the spliceosome. TopHat revealed cannonical splice junctions in roughly 30 non-intronic mRNAs, indicating that these messages are spliced. Conclusions: We demonstrate, for the first time, that the spliceosome can regulate expression of non-intronic mRNAs via one and/or two RNA cleavage events. We refer to this process as Spliceosome Mediated Decay (SMD). We report RNAseq data for two SM immunoprecipitation experiments and RNAseq datasets for the parental strain (BY4741), the prp40-1 mutant, and the rrp6M-NM-^T strain.
Project description:Project abstract : The trimethylation of histone H3 lysine 4 (H3K4me3) is a crucial factor in defining the promoter regions of active genes in all eukaryotes ranging from Saccharomyces cerevisiae (yeast) to humans. In budding yeast, this trimethylation process facilitated by the Set1 complex results in H3K4me3 requiring a prior mono-ubiquitination at the histone H2BK123 residue (H2Bub) by E2 enzyme Rad6 and E3 enzyme Bre1. A previous in vitro study suggested that ubiquitinated H2B directly facilitates H3K4me3. However, even low levels of global H2Bub is sufficient for the required H3K4me3 in yeast cells, thereby indicating that other factors resulting in the H2Bub-dependent H3K4me3 remain unknown. This study revealed the high level of correlation of H3K4me3 with chromatin recruitment of Rad6 at the genome-wide level. Rad6 is confirmd to interact and co-localize with Swd2/Cps35, a key factor for the H2Bub-dependent H3K4me3 in genes with high levels of H3K4me3 and intronic genes rather than non-intronic genes. This study therefore provides a mechanistic insight of the H2Bub-Rad6- Swd2/Cps35-H3K4me3 axis and its potential role in RNA biogenesis.
Project description:Purpose: The goals of this study were to determine whether the spliceosome interacts with non-intronic mRNAs Methods: RNAseq was performed on RNA that immunoprecipitated with the yeast SMD1 protein. Tandem-affinity-purified RNAs were extracted and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). We also performed RNAseq experiments on rRNA depleted total RNA extracted from an exosome mutant (rrp6Δ), a temperature-sensitive splicing mutant (prp40-1) and a parental strain (BY4741). The rRNA was depleted using the Invitrogen RiboMinus kit, according to manufactureres procedures. The depleted RNA was subsequently treated with Turbo DNAse I (Ambion) and RNAseq libraries were generated using the EpiCentre ScriptSeq kit (v1). Results: The SM RNAseq data identified a number of non-intronic mRNAs that appeard to be bound by the spliceosome. Among these was the BDF2 mRNA, which enocdes for a bromo-domain protein. BDF2 was highly enriched in both SM-IP datasets and was therefore analyzed in more detail. To determine if other non-intronic mRNAs could be regulated by the spliceosome, we analysed the transcriptome in the rrp6Δ, the prp40-1 and a parental strain. Bioinformatic analysis of these data sets revealed that roughly 1% of the non-intronic mRNAs in yeast could be targeted by the spliceosome. TopHat revealed cannonical splice junctions in roughly 30 non-intronic mRNAs, indicating that these messages are spliced. Conclusions: We demonstrate, for the first time, that the spliceosome can regulate expression of non-intronic mRNAs via one and/or two RNA cleavage events. We refer to this process as Spliceosome Mediated Decay (SMD).