Control of RNA pol II speed by PNUTS-PP1 and Spt5 dephosphorylation facilitates termination by a “sitting duck torpedo” mechanism
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PROVIDER: PRJNA554298 | ENA |
REPOSITORIES: ENA
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Project description:Control of transcription speed, which influences many co-transcriptional processes, is poorly understood. We report that PNUTS-PP1 phosphatase is a negative regulator of RNA pol II elongation rate. The PNUTS W401A mutation, which disrupts PP1 binding, causes genome-wide acceleration of transcription associated with hyper-phosphorylation of the Spt5 elongation factor. Immediately downstream of poly(A) sites, pol II decelerates from >2kb/min to <1 kb/min, which correlates with Spt5 dephosphorylation. Pol II deceleration and Spt5 dephosphorylation require poly(A) site recognition and the PNUTS-PP1 complex, which is in turn necessary for transcription termination. These results lead to a new model for termination, the “sitting duck torpedo” mechanism, where poly(A) site-dependent deceleration caused by PNUTS-PP1 and Spt5 dephosphorylation is required to convert pol II into a viable target for the Xrn2 terminator exonuclease. Spt5 and its bacterial homologue NusG therefore have related functions controlling kinetic competition between RNA polymerases and the termination factors that pursue them.
2019-10-30 | GSE134198 | GEO
Project description: Not available
| S-EPMC6927536 | biostudies-literature
Project description:The Pol II transcription cycle is ordered by CDKs and phosphatases. In fission yeast, Cdk9 phosphorylates carboxy-terminal repeats (CTRs) of Spt5 while inhibiting PP1 during elongation. Transcription past the cleavage and polyadenylation signal (CPS) coincides with PP1-dependent Spt5 dephosphorylation and leads to Pol II pausing with phosphorylated CTD-Ser2 (pSer2). Here we show this switch is conserved in humans: Cdk9 inhibition decreases phosphorylation of both PP1g and Spt5-Thr806 (pThr806), and induces pSer2 upstream of the CPS, whereas PP1 depletion increases pThr806. Moreover, in unperturbed cells, pThr806 is diminished in 3’-paused complexes where pSer2 is maximal. Cdk9 also phosphorylates Spt5 on Ser666, a PP1-refractory site between conserved KOW4 and KOW5 motifs; pSer666 increases upon promoter-proximal pause release and, in contrast to pThr806, persists beyond the CPS. We identify PP4—another target of inhibitory phosphorylation by Cdk9—as a pSer666 phosphatase. PP4 and PP1g are enriched at 5’ and 3’ ends of genes, respectively, consistent with pSer666 and pThr806 distributions. Therefore, distinct Cdk9-phosphatase switches operate on Spt5 at different steps in transcription.
2020-08-04 | GSE138548 | GEO
Project description:The end of the RNA polymerase II (Pol II) transcription cycle is strictly regulated to ensure proper mRNA maturation and prevent interference between neighboring genes. Pol II slowing downstream of the cleavage and polyadenylation signal (CPS) leads to recruitment of cleavage and polyadenylation factors and termination, but how this chain of events is initiated remains unclear. In a chemical-genetic screen we identified protein phosphatase 1 (PP1) isoforms as substrates of human positive transcription elongation factor b (P-TEFb), the cyclin-dependent kinase 9 (Cdk9)-cyclin T1 complex. Here we show that Cdk9 and PP1 govern phosphorylation of the conserved transcription factor Spt5 in the fission yeast Schizosaccharomyces pombe. Cdk9 phosphorylates both Spt5 and a negative regulatory site on the PP1 isoform Dis2. Sites phosphorylated by Cdk9 in the Spt5 carboxy-terminal domain (CTD) are dephosphorylated by Dis2 in vitro, and Cdk9 inhibition in vivo leads to rapid Spt5 dephosphorylation that is retarded by concurrent Dis2 inactivation. Chromatin immunoprecipitation and sequencing (ChIP-seq) analysis indicates that Spt5 is dephosphorylated as transcription complexes traverse the CPS, prior to or concomitant with Pol II pausing. A Dis2-inactivating mutation stabilizes Spt5 phosphorylation (pSpt5) on chromatin, promotes transcription beyond the normal termination zone detected by precision run-on transcription and sequencing (PRO-seq), and is suppressed by ablation of Cdk9 target sites in Spt5. These results support a model whereby the transition of Pol II from elongation to termination is regulated by opposing activities of Cdk9 and Dis2 towards their common substrate Spt5—a bistable switch analogous to a Cdk1-PP1 module that controls exit from mitosis.
2018-06-07 | GSE102590 | GEO
Project description:Mitotic exit requires extensive dephosphorylation of Ser/Thr residues by the PP1 and PP2A-B55 protein phosphatases in human cells. Several aspects of this are poorly understood including specific substrates and determinants of phosphatase specificity. Here we develop a novel in vitro assay, MRBLE-dephos, that allows multiplexing of dephosphorylation reactions to determine phosphatase specificity. Using MRBLE-dephos, we establish amino acid preferences of the residues surrounding the phosphorylation site for PP1 and PP2A-B55, which reveals common and unique preferences for the two phosphatases. We use specific inhibition of PP1 and PP2A-B55 in mitotic exit lysates coupled with quantitative phosphoproteomics to identify more than 2000 regulated phosphorylation sites and integrate this with mitotic interactomes to obtain a comprehensive map of mitotic dephosphorylation events. Importantly, the sites dephosphorylated during mitotic exit reveal key signatures that are consistent with the MRBLE-dephos results. We use these insights to specifically alter INCENP dephosphorylation kinetics at mitotic exit resulting in defective cytokinesis underscoring the biological relevance of our determined specificity principles. Finally, we provide a comprehensive characterization of PP1 binding motifs and show how these can shape dephosphorylation and how PP1 primes its own association with these motifs at mitotic exit. Collectively we provide a framework for understanding mitotic exit regulation by dephosphorylation and novel approaches to dissect protein phosphatase specificity.
2023-05-12 | MSV000091928 | MassIVE
Project description:The deletion of the protein phosphatase-1 (PP1) regulator NIPP1 is embryonic lethal during gastrulation, hinting at a key role of PP1-NIPP1 in lineage specification. Consistent with this notion we show here that a mild, stable overexpression of NIPP1 in HeLa cells caused a massive induction of genes of the mesenchymal lineage, in particular smooth/cardiac-muscle and matrix markers. This reprogramming was associated with the formation of actin-based stress fibers and retracting filopodia, and a reduced proliferation potential. The NIPP1-induced mesenchymal transition required functional substrate and PP1-binding domains, suggesting that it involves the selective dephosphorylation of substrates of PP1-NIPP1.
2015-04-04 | GSE67558 | GEO
Project description:The deletion of the protein phosphatase-1 (PP1) regulator NIPP1 is embryonic lethal during gastrulation, hinting at a key role of PP1-NIPP1 in lineage specification. Consistent with this notion we show here that a mild, stable overexpression of NIPP1 in HeLa cells caused a massive induction of genes of the mesenchymal lineage, in particular smooth/cardiac-muscle and matrix markers. This reprogramming was associated with the formation of actin-based stress fibers and retracting filopodia, and a reduced proliferation potential. The NIPP1-induced mesenchymal transition required functional substrate and PP1-binding domains, suggesting that it involves the selective dephosphorylation of substrates of PP1-NIPP1. In total 16 samples were processed. Four different cell lines were analysed: HTO_parental, HTO_NIPP1wt, HTO_NIPP1m (= alias NIPP1-Pm) and HTO_NIPP1-Pa. For each cell line 4 replicates were obtained. The HTO_parental cell line is the control cell line. For the HTO_NIPP1wt and the HTO_NIPP1-Pa the 4 replicates were obtained from two replicates of two different transgenic cell lines expressing FlagNIPP1wt (cell line wt n°1 and 2) and FlagNIPP1-Pa (cell line n°1 and 2), respectively. Each cell line was derived from the same parental control cell line.
2015-04-04 | E-GEOD-67558 | biostudies-arrayexpress
Project description:TOX4 is one of the regulatory proteins of PP1 phosphatases with poorly understood functions. Here we show that chromatin occupancy pattern of TOX4 resembles that of RNA polymerase II (Pol II), and its loss increases cellular level of C-terminal domain (CTD) phosphorylated Pol II but mainly decreases Pol II occupancy on promoters. In addition, elongation rate analyses by 4sUDRB-seq suggest that TOX4 restricts pause release and early elongation but promotes late elongation. Moreover, TT-seq analyses indicate that TOX4 loss mainly decreases transcriptional output. Mechanistically, TOX4 may restrict pause release through facilitating CTD serine 2 and DSIF dephosphorylation, and promote Pol II recycling and reinitiation through facilitating CTD serines 2 and 5 dephosphorylation. Furthermore, among the PP1 phosphatases, TOX4 preferentially binds PP1α and is capable of facilitating Pol II CTD dephosphorylation in vitro. These results lay the foundation for a better understanding of the role of TOX4 in transcriptional regulation.
2022-03-29 | GSE164277 | GEO
Project description:Spt5 is a highly conserved RNA polymerase II (Pol II)-associated pausing and elongation factor. However, its impact on global elongation and Pol II processivity in mammalian cells has not been clarified. Here, we show that depleting Spt5 in mouse embryonic fibroblasts (MEFs) does not cause global elongation defects or decreased elongation rates. Instead, in the absence of Spt5, a fraction of Pol II molecules are dislodged during elongation thus decreasing the number of Pol II complexes that complete the transcription cycle. Most strikingly, this decrease is restricted to a narrow window between 15-20 kb from the promoter, a distance which coincides with the stage where accelerating Pol II attains maximum elongation speed and processivity. Consequently, long genes show a greater dependency on Spt5 for optimal elongation efficiency and overall gene expression than short genes. We propose that an important role of Spt5 in mammalian elongation is to promote the processivity of those Pol II complexes that are transitioning towards maximum elongation speed 15-20 kb from the promoter.
2018-03-06 | GSE106313 | GEO
Project description:Termination of RNA polymerase II (Pol II) transcription is a key step, that is important for 3’end formation of functional mRNA, mRNA release and Pol II recycling. Even so, this underlying termination mechanism is not yet understood. Here, we demonstrate that the conserved and essential termination factor Seb1 interacts with Pol II near the end of the RNA exit channel and the Rpb4/7 stalk. Furthermore, the Seb1 interaction surface with Pol II largely overlaps with that of the elongation factor Spt5. Notably, Seb1 co-transcriptional recruitment is dependent on Spt5 de-phosphorylation by the conserved PP1 phosphatase Dis2, which also de-phosphorylates threonine 4 within the Pol II heptad repeated C-terminal domain. We propose that Dis2 orchestrates the transition from elongation to termination phase during the transcription cycle by mediating elongation to termination factor exchange and de-phosphorylation of Pol II C-terminal domain.
2018-12-26 | GSE111326 | GEO