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Vukovic I, Barnada SM, Ruffin JW, Karlin J, Lokareddy RK, Cingolani G, McMahon SB. Non-redundant roles for the human mRNA decapping cofactor paralogs DCP1a and DCP1b. Life Sci Alliance 2024; 7:e202402938. [PMID: 39256052 PMCID: PMC11387620 DOI: 10.26508/lsa.202402938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2024] [Revised: 08/21/2024] [Accepted: 08/21/2024] [Indexed: 09/12/2024] Open
Abstract
Eukaryotic gene expression is regulated at the transcriptional and post-transcriptional levels, with disruption of regulation contributing significantly to human diseases. The 5' m7G mRNA cap is a central node in post-transcriptional regulation, participating in both mRNA stabilization and translation efficiency. In mammals, DCP1a and DCP1b are paralogous cofactor proteins of the mRNA cap hydrolase DCP2. As lower eukaryotes have a single DCP1 cofactor, the functional advantages gained by this evolutionary divergence remain unclear. We report the first functional dissection of DCP1a and DCP1b, demonstrating that they are non-redundant cofactors of DCP2 with unique roles in decapping complex integrity and specificity. DCP1a is essential for decapping complex assembly and interactions between the decapping complex and mRNA cap-binding proteins. DCP1b is essential for decapping complex interactions with protein degradation and translational machinery. DCP1a and DCP1b impact the turnover of distinct mRNAs. The observation that different ontological groups of mRNA molecules are regulated by DCP1a and DCP1b, along with their non-redundant roles in decapping complex integrity, provides the first evidence that these paralogs have qualitatively distinct functions.
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Affiliation(s)
- Ivana Vukovic
- https://ror.org/00ysqcn41 Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Samantha M Barnada
- https://ror.org/00ysqcn41 Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Jon Karlin
- https://ror.org/00ysqcn41 Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ravi Kumar Lokareddy
- https://ror.org/008s83205 Academic Joint Departments - Biochemistry & Molecular Genetic, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Gino Cingolani
- https://ror.org/008s83205 Academic Joint Departments - Biochemistry & Molecular Genetic, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Steven B McMahon
- https://ror.org/00ysqcn41 Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Wang Q, Lin J. Homeostasis of mRNA concentrations through coupling transcription, export, and degradation. iScience 2024; 27:110531. [PMID: 39175768 PMCID: PMC11338957 DOI: 10.1016/j.isci.2024.110531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 04/16/2024] [Accepted: 07/15/2024] [Indexed: 08/24/2024] Open
Abstract
Many experiments showed that eukaryotic cells maintain a constant mRNA concentration upon various perturbations by actively regulating mRNA production and degradation rates, known as mRNA buffering. However, the underlying mechanism is still unknown. In this work, we unveil a mechanistic model of mRNA buffering: the releasing-shuttling (RS) model. The model incorporates two crucial proteins, X and Y, which play several roles, including transcription, decay, and export factors, in the different stages of mRNA metabolism. The RS model predicts the constant mRNA concentration under genome-wide genetic perturbations and cell volume changes, the slowed-down mRNA degradation after Pol II depletion, and the temporal transcription dynamics after exonuclease depletion, in agreement with multiple experiments. Finally, we present a list of X and Y candidates and propose an experimental method to identify X. Our work uncovers potentially universal pathways coupling transcription, export, and degradation that help cells maintain mRNA homeostasis.
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Affiliation(s)
- Qirun Wang
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Jie Lin
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
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Gillis A, Berry S. Global control of RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2024; 1867:195024. [PMID: 38552781 DOI: 10.1016/j.bbagrm.2024.195024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/11/2024]
Abstract
RNA polymerase II (Pol II) is the multi-protein complex responsible for transcribing all protein-coding messenger RNA (mRNA). Most research on gene regulation is focused on the mechanisms controlling which genes are transcribed when, or on the mechanics of transcription. How global Pol II activity is determined receives comparatively less attention. Here, we follow the life of a Pol II molecule from 'assembly of the complex' to nuclear import, enzymatic activity, and degradation. We focus on how Pol II spends its time in the nucleus, and on the two-way relationship between Pol II abundance and activity in the context of homeostasis and global transcriptional changes.
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Affiliation(s)
- Alexander Gillis
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia; UNSW RNA Institute, University of New South Wales, Sydney, Australia; Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
| | - Scott Berry
- EMBL Australia Node in Single Molecule Science, University of New South Wales, Sydney, Australia; UNSW RNA Institute, University of New South Wales, Sydney, Australia; Department of Molecular Medicine, School of Biomedical Sciences, University of New South Wales, Sydney, Australia
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Müller JM, Moos K, Baar T, Maier KC, Zumer K, Tresch A. Nuclear export is a limiting factor in eukaryotic mRNA metabolism. PLoS Comput Biol 2024; 20:e1012059. [PMID: 38753883 PMCID: PMC11135743 DOI: 10.1371/journal.pcbi.1012059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 05/29/2024] [Accepted: 04/09/2024] [Indexed: 05/18/2024] Open
Abstract
The eukaryotic mRNA life cycle includes transcription, nuclear mRNA export and degradation. To quantify all these processes simultaneously, we perform thiol-linked alkylation after metabolic labeling of RNA with 4-thiouridine (4sU), followed by sequencing of RNA (SLAM-seq) in the nuclear and cytosolic compartments of human cancer cells. We develop a model that reliably quantifies mRNA-specific synthesis, nuclear export, and nuclear and cytosolic degradation rates on a genome-wide scale. We find that nuclear degradation of polyadenylated mRNA is negligible and nuclear mRNA export is slow, while cytosolic mRNA degradation is comparatively fast. Consequently, an mRNA molecule generally spends most of its life in the nucleus. We also observe large differences in the nuclear export rates of different 3'UTR transcript isoforms. Furthermore, we identify genes whose expression is abruptly induced upon metabolic labeling. These transcripts are exported substantially faster than average mRNAs, suggesting the existence of alternative export pathways. Our results highlight nuclear mRNA export as a limiting factor in mRNA metabolism and gene regulation.
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Affiliation(s)
- Jason M. Müller
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Institute of Medical Statistics and Computational Biology, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Katharina Moos
- Institute of Medical Statistics and Computational Biology, Faculty of Medicine, University of Cologne, Cologne, Germany
- Institute of Medical Bioinformatics and Systems Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Till Baar
- Institute of Medical Statistics and Computational Biology, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Kerstin C. Maier
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Kristina Zumer
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Achim Tresch
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Institute of Medical Statistics and Computational Biology, Faculty of Medicine, University of Cologne, Cologne, Germany
- Center for Data and Simulation Science, University of Cologne, Cologne, Germany
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Bryll AR, Peterson CL. The circular logic of mRNA homeostasis. Transcription 2023; 14:18-26. [PMID: 36843061 PMCID: PMC10353332 DOI: 10.1080/21541264.2023.2183684] [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: 12/21/2022] [Revised: 02/13/2023] [Accepted: 02/17/2023] [Indexed: 02/28/2023] Open
Abstract
Eukaryotic cells rely upon dynamic, multifaceted regulation at each step of RNA biogenesis to maintain mRNA pools and ensure normal protein synthesis. Studies in budding yeast indicate a buffering phenomenon that preserves global mRNA levels through the reciprocal balancing of RNA synthesis rates and mRNA decay. In short, changes in transcription impact the efficiency of mRNA degradation and defects in either nuclear or cytoplasmic mRNA degradation are somehow sensed and relayed to control a compensatory change in mRNA transcription rates. Here, we review current views on molecular mechanisms that might explain this apparent bidirectional sensing process that ensures homeostasis of the stable mRNA pool.
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Affiliation(s)
- Alysia R. Bryll
- Program of Molecular Medicine, University of Massachusetts Chan Medical School, Worcester
- Medical Scientist Training Program, University of Massachusetts Chan Medical School, Worcester
| | - Craig L. Peterson
- Program of Molecular Medicine, University of Massachusetts Chan Medical School, Worcester
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Rahaman S, Faravelli S, Voegeli S, Becskei A. Polysome propensity and tunable thresholds in coding sequence length enable differential mRNA stability. SCIENCE ADVANCES 2023; 9:eadh9545. [PMID: 37756413 PMCID: PMC10530222 DOI: 10.1126/sciadv.adh9545] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 08/25/2023] [Indexed: 09/29/2023]
Abstract
The half-life of mRNAs, as well as their translation, increases in proportion to the optimal codons, indicating a tight coupling of codon-dependent differential translation and degradation. Little is known about the regulation of this coupling. We found that the mRNA stability gain in yeast depends on the mRNA coding sequence length. Below a critical length, codon optimality fails to affect the stability of mRNAs although they can be efficiently translated into short peptides and proteins. Above this threshold length, codon optimality-dependent differential mRNA stability emerges in a switch-like fashion, which coincides with a similar increase in the polysome propensity of the mRNAs. This threshold length can be tuned by the untranslated regions (UTR). Some of these UTRs can destabilize mRNAs without reducing translation, which plays a role in controlling the amplitude of the oscillatory expression of cell cycle genes. Our findings help understand the translation of short peptides from noncoding RNAs and the translation by localized monosomes in neurons.
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Affiliation(s)
- Sayanur Rahaman
- Biozentrum, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland
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RNA-controlled nucleocytoplasmic shuttling of mRNA decay factors regulates mRNA synthesis and a novel mRNA decay pathway. Nat Commun 2022; 13:7184. [PMID: 36418294 PMCID: PMC9684461 DOI: 10.1038/s41467-022-34417-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 10/25/2022] [Indexed: 11/27/2022] Open
Abstract
mRNA level is controlled by factors that mediate both mRNA synthesis and decay, including the 5' to 3' exonuclease Xrn1. Here we show that nucleocytoplasmic shuttling of several yeast mRNA decay factors plays a key role in determining both mRNA synthesis and decay. Shuttling is regulated by RNA-controlled binding of the karyopherin Kap120 to two nuclear localization sequences (NLSs) in Xrn1, location of one of which is conserved from yeast to human. The decaying RNA binds and masks NLS1, establishing a link between mRNA decay and Xrn1 shuttling. Preventing Xrn1 import, either by deleting KAP120 or mutating the two Xrn1 NLSs, compromises transcription and, unexpectedly, also cytoplasmic decay, uncovering a cytoplasmic decay pathway that initiates in the nucleus. Most mRNAs are degraded by both pathways - the ratio between them represents a full spectrum. Importantly, Xrn1 shuttling is required for proper responses to environmental changes, e.g., fluctuating temperatures, involving proper changes in mRNA abundance and in cell proliferation rate.
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Pérez-Ortín JE, Chávez S. Nucleo-cytoplasmic shuttling of RNA-binding factors: mRNA buffering and beyond. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2022; 1865:194849. [PMID: 35907432 DOI: 10.1016/j.bbagrm.2022.194849] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/18/2022] [Accepted: 07/23/2022] [Indexed: 06/15/2023]
Abstract
Gene expression is a highly regulated process that adapts RNAs and proteins content to the cellular context. Under steady-state conditions, mRNA homeostasis is robustly maintained by tight controls that act on both nuclear transcription and cytoplasmic mRNA stability. In recent years, it has been revealed that several RNA-binding proteins (RBPs) that perform functions in mRNA decay can move to the nucleus and regulate transcription. The RBPs involved in transcription can also travel to the cytoplasm and regulate mRNA degradation and/or translation. The multifaceted functions of these shuttling nucleo-cytoplasm RBPs have raised the possibility that they can act as mRNA metabolism coordinators. In addition, this indicates the existence of crosstalk mechanisms between the enzymatic machineries that drive the different mRNA life-cycle phases. The buffering of the mRNA concentration is the best known consequence of a transcription-degradation crosstalk counteraction, but alternative ways of RBP action can also imply enhanced gene regulation.
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Affiliation(s)
- José E Pérez-Ortín
- Instituto de Biotecnología y Biomedicina (Biotecmed), Facultad de Biológicas, Universitat de València. C/Dr. Moliner 50, E46100 Burjassot, Spain.
| | - Sebastián Chávez
- Departamento de Genética, Universidad de Sevilla and Instituto de Biomedicina de Sevilla (IBiS), Hospital Virgen del Rocío-CSIC-Universidad de Sevilla, 41013 Seville, Spain; Dirección de Evaluación y Acreditación, Agencia Andaluza del Conocimiento, Doña Berenguela s/n, planta 3ª C.P., 14006 Córdoba, Spain
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