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Aydin E, Schreiner S, Böhme J, Keil B, Weber J, Žunar B, Glatter T, Kilchert C. DEAD-box ATPase Dbp2 is the key enzyme in an mRNP assembly checkpoint at the 3'-end of genes and involved in the recycling of cleavage factors. Nat Commun 2024; 15:6829. [PMID: 39122693 PMCID: PMC11315920 DOI: 10.1038/s41467-024-51035-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 07/24/2024] [Indexed: 08/12/2024] Open
Abstract
mRNA biogenesis in the eukaryotic nucleus is a highly complex process. The numerous RNA processing steps are tightly coordinated to ensure that only fully processed transcripts are released from chromatin for export from the nucleus. Here, we present the hypothesis that fission yeast Dbp2, a ribonucleoprotein complex (RNP) remodelling ATPase of the DEAD-box family, is the key enzyme in an RNP assembly checkpoint at the 3'-end of genes. We show that Dbp2 interacts with the cleavage and polyadenylation complex (CPAC) and localises to cleavage bodies, which are enriched for 3'-end processing factors and proteins involved in nuclear RNA surveillance. Upon loss of Dbp2, 3'-processed, polyadenylated RNAs accumulate on chromatin and in cleavage bodies, and CPAC components are depleted from the soluble pool. Under these conditions, cells display an increased likelihood to skip polyadenylation sites and a delayed transcription termination, suggesting that levels of free CPAC components are insufficient to maintain normal levels of 3'-end processing. Our data support a model in which Dbp2 is the active component of an mRNP remodelling checkpoint that licenses RNA export and is coupled to CPAC release.
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Affiliation(s)
- Ebru Aydin
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Silke Schreiner
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Jacqueline Böhme
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Birte Keil
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Jan Weber
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany
| | - Bojan Žunar
- Department of Chemistry and Biochemistry, University of Zagreb Faculty of Food Technology and Biotechnology, Zagreb, Croatia
| | - Timo Glatter
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Cornelia Kilchert
- Institute of Biochemistry, Justus-Liebig University Giessen, Giessen, Germany.
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2
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Transcription and chromatin-based surveillance mechanism controls suppression of cryptic antisense transcription. Cell Rep 2021; 36:109671. [PMID: 34496258 PMCID: PMC8441049 DOI: 10.1016/j.celrep.2021.109671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/26/2020] [Accepted: 08/13/2021] [Indexed: 12/25/2022] Open
Abstract
Phosphorylation of the RNA polymerase II C-terminal domain Y1S2P3T4S5P6S7 consensus sequence coordinates key events during transcription, and its deregulation leads to defects in transcription and RNA processing. Here, we report that the histone deacetylase activity of the fission yeast Hos2/Set3 complex plays an important role in suppressing cryptic initiation of antisense transcription when RNA polymerase II phosphorylation is dysregulated due to the loss of Ssu72 phosphatase. Interestingly, although single Hos2 and Set3 mutants have little effect, loss of Hos2 or Set3 combined with ssu72Δ results in a synergistic increase in antisense transcription globally and correlates with elevated sensitivity to genotoxic agents. We demonstrate a key role for the Ssu72/Hos2/Set3 mechanism in the suppression of cryptic antisense transcription at the 3' end of convergent genes that are most susceptible to these defects, ensuring the fidelity of gene expression within dense genomes of simple eukaryotes.
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García-Reyes B, Kretz AL, Ruff JP, von Karstedt S, Hillenbrand A, Knippschild U, Henne-Bruns D, Lemke J. The Emerging Role of Cyclin-Dependent Kinases (CDKs) in Pancreatic Ductal Adenocarcinoma. Int J Mol Sci 2018; 19:E3219. [PMID: 30340359 PMCID: PMC6214075 DOI: 10.3390/ijms19103219] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/27/2018] [Accepted: 10/11/2018] [Indexed: 02/07/2023] Open
Abstract
The family of cyclin-dependent kinases (CDKs) has critical functions in cell cycle regulation and controlling of transcriptional elongation. Moreover, dysregulated CDKs have been linked to cancer initiation and progression. Pharmacological CDK inhibition has recently emerged as a novel and promising approach in cancer therapy. This idea is of particular interest to combat pancreatic ductal adenocarcinoma (PDAC), a cancer entity with a dismal prognosis which is owed mainly to PDAC's resistance to conventional therapies. Here, we review the current knowledge of CDK biology, its role in cancer and the therapeutic potential to target CDKs as a novel treatment strategy for PDAC.
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Affiliation(s)
- Balbina García-Reyes
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Anna-Laura Kretz
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Jan-Philipp Ruff
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Silvia von Karstedt
- Department of Translational Genomics, University Hospital Cologne, Weyertal 115b, 50931 Cologne, Germany.
- Cologne Excellence Cluster on Cellular Stress Response in Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Straße 26, 50931 Cologne, Germany.
| | - Andreas Hillenbrand
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Uwe Knippschild
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Doris Henne-Bruns
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
| | - Johannes Lemke
- Department of General and Visceral Surgery, Ulm University Hospital, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
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Sansó M, Levin RS, Lipp JJ, Wang VYF, Greifenberg AK, Quezada EM, Ali A, Ghosh A, Larochelle S, Rana TM, Geyer M, Tong L, Shokat KM, Fisher RP. P-TEFb regulation of transcription termination factor Xrn2 revealed by a chemical genetic screen for Cdk9 substrates. Genes Dev 2016; 30:117-31. [PMID: 26728557 PMCID: PMC4701974 DOI: 10.1101/gad.269589.115] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sansó et al. identified ∼100 putative substrates of human positive transcription elongation factor b (P-TEFb), which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II. The transcription cycle of RNA polymerase II (Pol II) is regulated at discrete transition points by cyclin-dependent kinases (CDKs). Positive transcription elongation factor b (P-TEFb), a complex of Cdk9 and cyclin T1, promotes release of paused Pol II into elongation, but the precise mechanisms and targets of Cdk9 action remain largely unknown. Here, by a chemical genetic strategy, we identified ∼100 putative substrates of human P-TEFb, which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II, which we validated as a bona fide P-TEFb substrate in vivo and in vitro. Phosphorylation by Cdk9 or phosphomimetic substitution of its target residue, Thr439, enhanced enzymatic activity of Xrn2 on synthetic substrates in vitro. Conversely, inhibition or depletion of Cdk9 or mutation of Xrn2-Thr439 to a nonphosphorylatable Ala residue caused phenotypes consistent with inefficient termination in human cells: impaired Xrn2 chromatin localization and increased readthrough transcription of endogenous genes. Therefore, in addition to its role in elongation, P-TEFb regulates termination by promoting chromatin recruitment and activation of a cotranscriptional RNA processing enzyme, Xrn2.
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Affiliation(s)
- Miriam Sansó
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Rebecca S Levin
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Jesse J Lipp
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Vivien Ya-Fan Wang
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Ann Katrin Greifenberg
- Department of Structural Immunology, Institute of Innate Immunity, University of Bonn, 53127 Bonn, Germany
| | - Elizabeth M Quezada
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Akbar Ali
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Animesh Ghosh
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Stéphane Larochelle
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Tariq M Rana
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Matthias Geyer
- Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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Deletion of Genes Encoding Arginase Improves Use of "Heavy" Isotope-Labeled Arginine for Mass Spectrometry in Fission Yeast. PLoS One 2015; 10:e0129548. [PMID: 26075619 PMCID: PMC4468061 DOI: 10.1371/journal.pone.0129548] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 05/11/2015] [Indexed: 11/19/2022] Open
Abstract
The use of "heavy" isotope-labeled arginine for stable isotope labeling by amino acids in cell culture (SILAC) mass spectrometry in the fission yeast Schizosaccharomyces pombe is hindered by the fact that under normal conditions, arginine is extensively catabolized in vivo, resulting in the appearance of "heavy"-isotope label in several other amino acids, most notably proline, but also glutamate, glutamine and lysine. This "arginine conversion problem" significantly impairs quantification of mass spectra. Previously, we developed a method to prevent arginine conversion in fission yeast SILAC, based on deletion of genes involved in arginine catabolism. Here we show that although this method is indeed successful when (13)C6-arginine (Arg-6) is used for labeling, it is less successful when (13)C6(15)N4-arginine (Arg-10), a theoretically preferable label, is used. In particular, we find that with this method, "heavy"-isotope label derived from Arg-10 is observed in amino acids other than arginine, indicating metabolic conversion of Arg-10. Arg-10 conversion, which severely complicates both MS and MS/MS analysis, is further confirmed by the presence of (13)C5(15)N2-arginine (Arg-7) in arginine-containing peptides from Arg-10-labeled cells. We describe how all of the problems associated with the use of Arg-10 can be overcome by a simple modification of our original method. We show that simultaneous deletion of the fission yeast arginase genes car1+ and aru1+ prevents virtually all of the arginine conversion that would otherwise result from the use of Arg-10. This solution should enable a wider use of heavy isotope-labeled amino acids in fission yeast SILAC.
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