Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision. ChIP-Seq of RNA polymerase II was performed with WT and Elongain C deletion mutant (elc1M-bM-^HM-^F) cells. 4H8 antibody against the Rpb1 C-terminal domain was used for RNA polymerase II immunoprecipitation, whilst mouse IgG antibody was used for control immunoprecipitations. Two biological replicates were performed for both WT and elc1M-bM-^HM-^F.
Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision. Total RNA was extracted from WT or Elongin C deletion mutant (elc1M-bM-^HM-^F) cells and strand-specific RNA-Seq was performed. Three biological replicates were performed for WT and elc1M-bM-^HM-^F.
Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision.
Project description:Anti-sense non-coding transcripts, genes-within-genes, and convergent gene pairs are prevalent among eukaryotes. The existence of such transcription units raises the question of what happens when RNA polymerase II (RNAPII) molecules collide head-to-head. Here we use a combination of biochemical and genetic approaches in yeast to show that polymerases transcribing opposite DNA strands cannot bypass each other. RNAPII stops, but does not dissociate upon head-to-head collision in vitro, suggesting that opposing polymerases represent insurmountable obstacles for each other. Head-to-head collision in vivo results in RNAPII stopping as well, and removal of collided RNAPII from the DNA template can be achieved via ubiquitylation-directed proteolysis. Indeed, in cells lacking efficient RNAPII poly-ubiquitylation, the half-life of collided polymerases increases, so that these can be detected between convergent genes by ChIP-Seq. These results provide new insight into fundamental mechanisms of gene traffic control, and point to an unexplored effect of anti-sense transcription on gene regulation via polymerase collision.
Project description:During eukaryotic transcription, RNA polymerase II undergoes dynamic post-translational modification on the C-terminal domain (CTD) of the largest subunit , generating a sophisticated PTM landscape for the spatiotemporal recruitment to transcriptional regulators. To delineate the protein interactomes recruited to Pol II at different stages of transcription, we in vitro reconstructed phosphorylation patterns of the CTD at Ser5 and Ser2 positions, the hallmark phosphorylation at the initation and productive elongation stages of transcription, respectively. Distinctive protein interactomes indicates different proteins are recruited to RNA polymerase II at different stages of transcription by the phosphorylation of Ser2 and Ser5 of the CTD heptads. Calcium Homeostasis Endoplasmic Reticulum Protein (CHERP) specifically binds to the Ser2 of the heptad. The loss of the interaction between CHERP and Pol II results in broad alternative splicing events. Our method points to a new method to distinguish the PTM codes that coordinate the transcription process.
Project description:RNA polymerase II (Pol II) subunits are thought to be involved in various transcription-associated processes, but it is unclear whether they play different regulatory roles in modulating gene expression. Here, we performed nascent and mature transcript sequencing after the acute degradation of 12 mammalian Pol II subunits and profiled their genomic binding sites and protein interactomes to dissect their molecular functions. We found that Pol II subunits contribute differently to Pol II cellular localization and transcription process and preferentially regulate RNA processing (such as RNA splicing and 3’ end maturation). Genes sensitive to the depletion of different Pol II subunits tend to be involved in diverse biological functions and show different RNA half-lives. Sequences, associated protein factors, and RNA structures are correlated with Pol II subunit-mediated differential gene expression. These findings collectively suggest that the heterogeneity of Pol II and different genes appear to depend on some of the subunits.
Project description:Animal germline development and fertility relies on paralogs of general transcription factors that recruit RNA polymerase II to ensure cell type-specific gene expression. It remains unclear whether gene expression processes downstream of such paralog-based transcription is distinct from that of canonical RNA polymerase II genes. In Drosophila, the testis-specific TBP-associated factors (tTAFs) activate over a thousand spermatocyte-specific gene promoters to enable meiosis and germ cell differentiation. Here we show that efficient termination of tTAF-activated transcription requires a testis-specific Polymerase Associated Factor 1 Complex (tPAF) composed of paralogs of canonical Polymerase Associated Factor 1 Complex (PAF1C) proteins. Defective transcription termination in tPAF mutants causes aberrant expression of hundreds of downstream genes due to read-in transcription, compromising cell type-specific gene expression in spermatocytes. Consistently, tPAF is required for the segregation of meiotic chromosomes, sperm individualisation, and male fertility. Comparative in vivo proximity labeling assays of tPAF and PAF1C showed tPAF-specific association with tTAF as well as connections to central RNA polymerase II termination factors. Our study uncovers transcription termination as a developmentally regulated process required for cell type-specific gene expression.
Project description:Animal germline development and fertility relies on paralogs of general transcription factors that recruit RNA polymerase II to ensure cell type-specific gene expression. It remains unclear whether gene expression processes downstream of such paralog-based transcription is distinct from that of canonical RNA polymerase II genes. In Drosophila, the testis-specific TBP-associated factors (tTAFs) activate over a thousand spermatocyte-specific gene promoters to enable meiosis and germ cell differentiation. Here we show that efficient termination of tTAF-activated transcription requires a testis-specific Polymerase Associated Factor 1 Complex (tPAF) composed of paralogs of canonical Polymerase Associated Factor 1 Complex (PAF1C) proteins. Defective transcription termination in tPAF mutants causes aberrant expression of hundreds of downstream genes due to read-in transcription, compromising cell type-specific gene expression in spermatocytes. Consistently, tPAF is required for the segregation of meiotic chromosomes, sperm individualisation, and male fertility. Comparative in vivo proximity labeling assays of tPAF and PAF1C showed tPAF-specific association with tTAF as well as connections to central RNA polymerase II termination factors. Our study uncovers transcription termination as a developmentally regulated process required for cell type-specific gene expression.