Knockout of PP1 in Leishmania major reveals a critical role for protein phosphatase 1 during RNA polymerase II transcription termination
Ontology highlight
ABSTRACT:
ORGANISM(S): Leishmania major
PROVIDER: GSE200788 | GEO | 2022/10/01
REPOSITORIES: GEO
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Project description:Base J is a modified DNA base that is enriched at RNA polymerase II termination sites and telomeres. We previously found that base J functions to prevent readthrough transcription within gene clusters in T. brucei. We now identify a complex in Leishmania and T. brucei composed of PNUTS, PP1, Wdr82 and a J-binding protein (JBP3). We show the RNAi ablation of PNUTS in T. brucei leads to readthrough transcription and expression of downstream genes.
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Project description:Base J is a modified DNA base that is enriched at RNA polymerase II termination sites. We previously found that base J functions to prevent readthrough transcription within gene clusters via the PJW/PP1 complex. Analysis of the complex in T. brucei faild to identify the catalytic PP1 component. We now show the RNAi ablation of PP1-1 in T. brucei leads to readthrough transcription and expression of downstream genes.
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Project description:Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-protein phosphatase 1 (PP1) complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion also enhances global KSHV gene expression and overall viral replication. Reflecting its host gene activities, PNUTS binds viral RNAs downstream of polyadenylation sites, restricts transcription readthrough of viral genes, and requires PP1 interaction. Surprisingly, PNUTS represses the KSHV reporter by decreasing productive elongation at the 5´-end of the gene. From these data, we conclude that PNUTS' activity forms an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
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Project description:Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-protein phosphatase 1 (PP1) complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion also enhances global KSHV gene expression and overall viral replication. Reflecting its host gene activities, PNUTS binds viral RNAs downstream of polyadenylation sites, restricts transcription readthrough of viral genes, and requires PP1 interaction. Surprisingly, PNUTS represses the KSHV reporter by decreasing productive elongation at the 5´-end of the gene. From these data, we conclude that PNUTS' activity forms an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
2022-11-19 | GSE200991 | GEO
Project description:Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-protein phosphatase 1 (PP1) complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion also enhances global KSHV gene expression and overall viral replication. Reflecting its host gene activities, PNUTS binds viral RNAs downstream of polyadenylation sites, restricts transcription readthrough of viral genes, and requires PP1 interaction. Surprisingly, PNUTS represses the KSHV reporter by decreasing productive elongation at the 5´-end of the gene. From these data, we conclude that PNUTS' activity forms an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
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Project description:Control of RNA Polymerase II (pol II) elongation is a critical component of gene expression in mammalian cells. The PNUTS-protein phosphatase 1 (PP1) complex controls elongation rates, slowing pol II after polyadenylation sites to promote termination. The Kaposi's sarcoma-associated herpesvirus (KSHV) co-opts pol II to express its genes, but little is known about its regulation of pol II elongation. We identified PNUTS as a suppressor of a KSHV reporter gene in a genome-wide CRISPR screen. PNUTS depletion also enhances global KSHV gene expression and overall viral replication. Reflecting its host gene activities, PNUTS binds viral RNAs downstream of polyadenylation sites, restricts transcription readthrough of viral genes, and requires PP1 interaction. Surprisingly, PNUTS represses the KSHV reporter by decreasing productive elongation at the 5´-end of the gene. From these data, we conclude that PNUTS' activity forms an intrinsic barrier to KSHV replication likely by suppressing pol II elongation at promoter-proximal regions.
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Project description:Upon recruitment to active enhancers and promoters, RNA polymerase II (Pol_II) generates short non-coding transcripts of unclear function. The mechanisms that control the length and the amount of ncRNAs generated by cis-regulatory elements are largely unknown. Here, we show that the adapter protein WDR82 and its associated complexes actively limit such non-coding transcription. WDR82 targets the SET1/COMPASS H3K4 methyltransferase and the nuclear Protein Phosphatase 1 (PP1) complexes to the initiating Pol_II. WDR82 and PP1 also interact with components of the transcriptional termination and RNA processing machineries. Depletion of WDR82, SET1 or the PP1 subunit required for its nuclear import caused distinct but overlapping transcription termination defects at highly expressed genes, active enhancers and promoters, thus enabling the increased synthesis of unusually long ncRNAs. These data indicate that transcription initiated from cis-regulatory elements is tightly coordinated with termination mechanisms that impose the synthesis of short RNAs. polyA-mRNAs or 4sU-labeled RNAs from BMDMs, either untreated or treated for with lipopolysaccharide (LPS) for the indicated time. Experiments were carried out in cells containing either a short hairpin targeting either of these: 1) Wdr82; 2) Set1a+Set1b; 3) Pnuts; or the empty vector (LMP) or a scrambled as a control. When specified, cells were pre-treated with 5,6-Dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) in order to prevent RNA polymerase II elongation.
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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.
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Project description:Protein-coding genes in kinetoplastid protists are transcribed from polycistronic arrays, yielding RNA precursors which are processed to form mature transcripts bearing a 5’ spliced leader (SL) and 3’ poly(A) tract. Regions of transcription initiation and termination lack known eukaryotic promoter and terminator elements, and current data suggest that transcription is instead regulated predominantly through epigenetic mechanisms. Several epigenetic marks, including histone modifications, histone variants, and an atypical DNA modification known as base J have been localized to regions of transcription initiation or termination in Trypanosoma brucei, Trypanosoma cruzi, and/or Leishmania major. Despite this conservation, the phenotypes of base J mutants vary significantly across trypanosomatids, suggesting that the specific epigenetic networks governing transcription initiation and termination have diverged significantly during evolution. In this light, we sought to characterize and compare the roles of the histone variants H2A.Z, H2B.V, and H3.V in L. major. As in T. brucei, the histone variants H2A.Z and H2B.V were shown to be essential in L. major using a powerful quantitative plasmid segregation-based test. In contrast and again similar to T. brucei, H3.V is not essential in Leishmania as H3.V-null lines grew normally, resembled WT, and remained infectious. Using SL-primed RNA-seq, we found that H3.V-null parasites have steady-state transcript levels comparable to WT parasites and display no defects in the efficiency of transcription termination at convergent strand switch regions (SSRs). Our results show a conservation of histone variant phenotypes between L. major and T. brucei, in contrast to the phenotypes associated with the epigenetic DNA base J modification.
2013-10-26 | GSE51737 | 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.
2015-04-04 | GSE67558 | GEO