1
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Yamagishi R, Inagaki H, Suzuki J, Hosoda N, Sugiyama H, Tomita K, Hotta T, Hoshino SI. Concerted action of ataxin-2 and PABPC1-bound mRNA poly(A) tail in the formation of stress granules. Nucleic Acids Res 2024; 52:9193-9209. [PMID: 38869059 PMCID: PMC11347130 DOI: 10.1093/nar/gkae497] [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: 09/25/2023] [Revised: 05/24/2024] [Accepted: 05/29/2024] [Indexed: 06/14/2024] Open
Abstract
Stress induces global stabilization of the mRNA poly(A) tail (PAT) and the assembly of untranslated poly(A)-tailed mRNA into mRNPs that accumulate in stress granules (SGs). While the mechanism behind stress-induced global PAT stabilization has recently emerged, the biological significance of PAT stabilization under stress remains elusive. Here, we demonstrate that stress-induced PAT stabilization is a prerequisite for SG formation. Perturbations in PAT length impact SG formation; PAT shortening, achieved by overexpressing mRNA deadenylases, inhibits SG formation, whereas PAT lengthening, achieved by overexpressing their dominant negative mutants or downregulating deadenylases, promotes it. PABPC1, which specifically binds to the PAT, is crucial for SG formation. Complementation analyses reveal that the PABC/MLLE domain of PABPC1, responsible for binding PAM2 motif-containing proteins, plays a key role. Among them, ataxin-2 is a known SG component. A dominant-negative approach reveals that the PAM2 motif of ataxin-2 is essential for SG formation. Notably, ataxin-2 increases stress sensitivity, lowering the threshold for SG formation, probably by promoting the aggregation of PABPC1-bound mRNA. The C-terminal region is responsible for the self-aggregation of ataxin-2. These findings underscore the critical roles of mRNA PAT, PABPC1 and ataxin-2 in SG formation and provide mechanistic insights into this process.
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Affiliation(s)
- Ryota Yamagishi
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hiroto Inagaki
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Jun Suzuki
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Nao Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Haruka Sugiyama
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Kazunori Tomita
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Takashi Hotta
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Shin-ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
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2
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Chang X, Qu F, Li C, Zhang J, Zhang Y, Xie Y, Fan Z, Bian J, Wang J, Li Z, Xu X. Development and therapeutic potential of GSPT1 molecular glue degraders: A medicinal chemistry perspective. Med Res Rev 2024; 44:1727-1767. [PMID: 38314926 DOI: 10.1002/med.22024] [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: 09/20/2023] [Revised: 12/18/2023] [Accepted: 01/21/2024] [Indexed: 02/07/2024]
Abstract
Unprecedented therapeutic targeting of previously undruggable proteins has now been achieved by molecular-glue-mediated proximity-induced degradation. As a small GTPase, G1 to S phase transition 1 (GSPT1) interacts with eRF1, the translation termination factor, to facilitate the process of translation termination. Studied demonstrated that GSPT1 plays a vital role in the acute myeloid leukemia (AML) and MYC-driven lung cancer. Thus, molecular glue (MG) degraders targeting GSPT1 is a novel and promising approach for treating AML and MYC-driven cancers. In this Perspective, we briefly summarize the structural and functional aspects of GSPT1, highlighting the latest advances and challenges in MG degraders, as well as some representative patents. The structure-activity relationships, mechanism of action and pharmacokinetic features of MG degraders are emphasized to provide a comprehensive compendium on the rational design of GSPT1 MG degraders. We hope to provide an updated overview, and design guide for strategies targeting GSPT1 for the treatment of cancer.
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Affiliation(s)
- Xiujin Chang
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Fangui Qu
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Chunxiao Li
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Jingtian Zhang
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yanqing Zhang
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yuanyuan Xie
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Zhongpeng Fan
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Jinlei Bian
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Jubo Wang
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Zhiyu Li
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Xi Xu
- Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
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3
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Chang Y, Keramatnia F, Ghate PS, Nishiguchi G, Gao Q, Iacobucci I, Yang L, Chepyala D, Mishra A, High AA, Goto H, Akahane K, Peng J, Yang JJ, Fischer M, Rankovic Z, Mullighan CG. The orally bioavailable GSPT1/2 degrader SJ6986 exhibits in vivo efficacy in acute lymphoblastic leukemia. Blood 2023; 142:629-642. [PMID: 37172201 PMCID: PMC10447621 DOI: 10.1182/blood.2022017813] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 04/17/2023] [Accepted: 04/17/2023] [Indexed: 05/14/2023] Open
Abstract
Advancing cure rates for high-risk acute lymphoblastic leukemia (ALL) has been limited by the lack of agents that effectively kill leukemic cells, sparing normal hematopoietic tissue. Molecular glues direct the ubiquitin ligase cellular machinery to target neosubstrates for protein degradation. We developed a novel cereblon modulator, SJ6986, that exhibits potent and selective degradation of GSPT1 and GSPT2 and cytotoxic activity against childhood cancer cell lines. Here, we report in vitro and in vivo testing of the activity of this agent in a panel of ALL cell lines and xenografts. SJ6986 exhibited similar cytotoxicity to the previously described GSPT1 degrader CC-90009 in a panel of leukemia cell lines in vitro, resulting in apoptosis and perturbation of cell cycle progression. SJ6986 was more effective than CC-90009 in suppressing leukemic cell growth in vivo, partly attributable to favorable pharmacokinetic properties, and did not significantly impair differentiation of human CD34+ cells ex vivo. Genome-wide CRISPR/Cas9 screening of ALL cell lines treated with SJ6986 confirmed that components of the CRL4CRBN complex, associated adaptors, regulators, and effectors were integral in mediating the action of SJ6986. SJ6986 is a potent, selective, orally bioavailable GSPT1/2 degrader that shows broad antileukemic activity and has potential for clinical development.
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Affiliation(s)
- Yunchao Chang
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Fatemeh Keramatnia
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN
| | - Pankaj S. Ghate
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Gisele Nishiguchi
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Qingsong Gao
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Ilaria Iacobucci
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Lei Yang
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Divyabharathi Chepyala
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Ashutosh Mishra
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Anthony A. High
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Hiroaki Goto
- Division of Hemato-Oncology/Regenerative Medicine, Kanagawa Children’s Medical Center, Yokohama, Japan
| | - Koshi Akahane
- Department of Pediatrics, School of Medicine, University of Yamanashi, Chuo, Japan
| | - Junmin Peng
- Center for Proteomics and Metabolomics, St. Jude Children’s Research Hospital, Memphis, TN
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Jun J. Yang
- Department of Pharmaceutical Sciences, St. Jude Children’s Research Hospital, Memphis, TN
| | - Marcus Fischer
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center, Memphis, TN
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN
- Cancer Biology Program, St. Jude Children’s Research Hospital, Memphis, TN
| | - Zoran Rankovic
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
- Cancer Biology Program, St. Jude Children’s Research Hospital, Memphis, TN
| | - Charles G. Mullighan
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
- Hematological Malignancies Program, St. Jude Children’s Research Hospital, Memphis, TN
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4
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Mihalič F, Simonetti L, Giudice G, Sander MR, Lindqvist R, Peters MBA, Benz C, Kassa E, Badgujar D, Inturi R, Ali M, Krystkowiak I, Sayadi A, Andersson E, Aronsson H, Söderberg O, Dobritzsch D, Petsalaki E, Överby AK, Jemth P, Davey NE, Ivarsson Y. Large-scale phage-based screening reveals extensive pan-viral mimicry of host short linear motifs. Nat Commun 2023; 14:2409. [PMID: 37100772 PMCID: PMC10132805 DOI: 10.1038/s41467-023-38015-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 04/12/2023] [Indexed: 04/28/2023] Open
Abstract
Viruses mimic host short linear motifs (SLiMs) to hijack and deregulate cellular functions. Studies of motif-mediated interactions therefore provide insight into virus-host dependencies, and reveal targets for therapeutic intervention. Here, we describe the pan-viral discovery of 1712 SLiM-based virus-host interactions using a phage peptidome tiling the intrinsically disordered protein regions of 229 RNA viruses. We find mimicry of host SLiMs to be a ubiquitous viral strategy, reveal novel host proteins hijacked by viruses, and identify cellular pathways frequently deregulated by viral motif mimicry. Using structural and biophysical analyses, we show that viral mimicry-based interactions have similar binding strength and bound conformations as endogenous interactions. Finally, we establish polyadenylate-binding protein 1 as a potential target for broad-spectrum antiviral agent development. Our platform enables rapid discovery of mechanisms of viral interference and the identification of potential therapeutic targets which can aid in combating future epidemics and pandemics.
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Affiliation(s)
- Filip Mihalič
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Husargatan 3, 751 23, Uppsala, Sweden
| | - Leandro Simonetti
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Girolamo Giudice
- European Molecular Biology Laboratory-European Bioinformatics Institute, Hinxton, CB10 1SD, UK
| | - Marie Rubin Sander
- Department of Pharmaceutical Biosciences, Uppsala University, Husargatan 3, Box 591, SE-751 24, Uppsala, Sweden
| | - Richard Lindqvist
- Department of Clinical Microbiology, Umeå University, 90187, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90186, Umeå, Sweden
| | - Marie Berit Akpiroro Peters
- Department of Clinical Microbiology, Umeå University, 90187, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90186, Umeå, Sweden
| | - Caroline Benz
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Eszter Kassa
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Dilip Badgujar
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Raviteja Inturi
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Husargatan 3, 751 23, Uppsala, Sweden
| | - Muhammad Ali
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Izabella Krystkowiak
- Division of Cancer Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK
| | - Ahmed Sayadi
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Eva Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Husargatan 3, 751 23, Uppsala, Sweden
| | - Hanna Aronsson
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Husargatan 3, 751 23, Uppsala, Sweden
| | - Ola Söderberg
- Department of Pharmaceutical Biosciences, Uppsala University, Husargatan 3, Box 591, SE-751 24, Uppsala, Sweden
| | - Doreen Dobritzsch
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden
| | - Evangelia Petsalaki
- European Molecular Biology Laboratory-European Bioinformatics Institute, Hinxton, CB10 1SD, UK
| | - Anna K Överby
- Department of Clinical Microbiology, Umeå University, 90187, Umeå, Sweden
- Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, 90186, Umeå, Sweden
| | - Per Jemth
- Department of Medical Biochemistry and Microbiology, Uppsala University, Box 582, Husargatan 3, 751 23, Uppsala, Sweden.
| | - Norman E Davey
- Division of Cancer Biology, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK.
| | - Ylva Ivarsson
- Department of Chemistry - BMC, Uppsala University, Box 576, Husargatan 3, 751 23, Uppsala, Sweden.
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5
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Devan SK, Schott-Verdugo S, Müntjes K, Bismar L, Reiners J, Hachani E, Schmitt L, Höppner A, Smits SHJ, Gohlke H, Feldbrügge M. A MademoiseLLE domain binding platform links the key RNA transporter to endosomes. PLoS Genet 2022; 18:e1010269. [PMID: 35727840 PMCID: PMC9249222 DOI: 10.1371/journal.pgen.1010269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 07/01/2022] [Accepted: 05/20/2022] [Indexed: 11/19/2022] Open
Abstract
Spatiotemporal expression can be achieved by transport and translation of mRNAs at defined subcellular sites. An emerging mechanism mediating mRNA trafficking is microtubule-dependent co-transport on shuttling endosomes. Although progress has been made in identifying various components of the endosomal mRNA transport machinery, a mechanistic understanding of how these RNA-binding proteins are connected to endosomes is still lacking. Here, we demonstrate that a flexible MademoiseLLE (MLLE) domain platform within RNA-binding protein Rrm4 of Ustilago maydis is crucial for endosomal attachment. Our structure/function analysis uncovered three MLLE domains at the C-terminus of Rrm4 with a functionally defined hierarchy. MLLE3 recognises two PAM2-like sequences of the adaptor protein Upa1 and is essential for endosomal shuttling of Rrm4. MLLE1 and MLLE2 are most likely accessory domains exhibiting a variable binding mode for interaction with currently unknown partners. Thus, endosomal attachment of the mRNA transporter is orchestrated by a sophisticated MLLE domain binding platform.
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Affiliation(s)
- Senthil-Kumar Devan
- Institute of Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Stephan Schott-Verdugo
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Institute of Biological Information Processing (IBI-7: Structural Bioinformatics), and Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Kira Müntjes
- Institute of Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Lilli Bismar
- Institute of Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
| | - Jens Reiners
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Eymen Hachani
- Institute of Biochemistry I, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry I, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Astrid Höppner
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sander HJ Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Institute of Biochemistry I, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Holger Gohlke
- John von Neumann Institute for Computing (NIC), Jülich Supercomputing Centre (JSC), Institute of Biological Information Processing (IBI-7: Structural Bioinformatics), and Institute of Bio- and Geosciences (IBG-4: Bioinformatics), Forschungszentrum Jülich GmbH, Jülich, Germany
- Institute for Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Michael Feldbrügge
- Institute of Microbiology, Heinrich Heine University Düsseldorf, Cluster of Excellence on Plant Sciences, Düsseldorf, Germany
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6
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Zhouravleva GA, Bondarev SA, Zemlyanko OM, Moskalenko SE. Role of Proteins Interacting with the eRF1 and eRF3 Release Factors in the Regulation of Translation and Prionization. Mol Biol 2022. [DOI: 10.1134/s0026893322010101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Abstract
Viruses have evolved diverse strategies to hijack the cellular gene expression system for their replication. The poly(A) binding proteins (PABPs), a family of critical gene expression factors, are viruses' common targets. PABPs act not only as a translation factor but also as a key factor of mRNA metabolism. During viral infections, the activities of PABPs are manipulated by various viruses, subverting the host translation machinery or evading the cellular antiviral defense mechanism. Viruses harness PABPs by modifying their stability, complex formation with other translation initiation factors, or subcellular localization to promote viral mRNAs translation while shutting off or competing with host protein synthesis. For the past decade, many studies have demonstrated the PABPs' roles during viral infection. This review summarizes a comprehensive perspective of PABPs' roles during viral infection and how viruses evade host antiviral defense through the manipulations of PABPs.
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Affiliation(s)
- Jie Gao
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, China
| | - Yan-Dong Tang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin, China
| | - Wei Hu
- The State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, China
- State Key Laboratory of Genetic Engineering, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai, China
| | - Chunfu Zheng
- Department of Immunology, School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Alberta, Canada
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8
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Mattijssen S, Kozlov G, Fonseca BD, Gehring K, Maraia RJ. LARP1 and LARP4: up close with PABP for mRNA 3' poly(A) protection and stabilization. RNA Biol 2021; 18:259-274. [PMID: 33522422 PMCID: PMC7928012 DOI: 10.1080/15476286.2020.1868753] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 12/06/2020] [Accepted: 12/17/2020] [Indexed: 02/06/2023] Open
Abstract
La-related proteins (LARPs) share a La motif (LaM) followed by an RNA recognition motif (RRM). Together these are termed the La-module that, in the prototypical nuclear La protein and LARP7, mediates binding to the UUU-3'OH termination motif of nascent RNA polymerase III transcripts. We briefly review La and LARP7 activities for RNA 3' end binding and protection from exonucleases before moving to the more recently uncovered poly(A)-related activities of LARP1 and LARP4. Two features shared by LARP1 and LARP4 are direct binding to poly(A) and to the cytoplasmic poly(A)-binding protein (PABP, also known as PABPC1). LARP1, LARP4 and other proteins involved in mRNA translation, deadenylation, and decay, contain PAM2 motifs with variable affinities for the MLLE domain of PABP. We discuss a model in which these PABP-interacting activities contribute to poly(A) pruning of active mRNPs. Evidence that the SARS-CoV-2 RNA virus targets PABP, LARP1, LARP 4 and LARP 4B to control mRNP activity is also briefly reviewed. Recent data suggests that LARP4 opposes deadenylation by stabilizing PABP on mRNA poly(A) tails. Other data suggest that LARP1 can protect mRNA from deadenylation. This is dependent on a PAM2 motif with unique characteristics present in its La-module. Thus, while nuclear La and LARP7 stabilize small RNAs with 3' oligo(U) from decay, LARP1 and LARP4 bind and protect mRNA 3' poly(A) tails from deadenylases through close contact with PABP.Abbreviations: 5'TOP: 5' terminal oligopyrimidine, LaM: La motif, LARP: La-related protein, LARP1: La-related protein 1, MLLE: mademoiselle, NTR: N-terminal region, PABP: cytoplasmic poly(A)-binding protein (PABPC1), Pol III: RNA polymerase III, PAM2: PABP-interacting motif 2, PB: processing body, RRM: RNA recognition motif, SG: stress granule.
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Affiliation(s)
- Sandy Mattijssen
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Guennadi Kozlov
- Department of Biochemistry & Centre for Structural Biology, McGill University, Montreal, Canada
| | | | - Kalle Gehring
- Department of Biochemistry & Centre for Structural Biology, McGill University, Montreal, Canada
| | - Richard J. Maraia
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
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9
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Mattijssen S, Kozlov G, Gaidamakov S, Ranjan A, Fonseca BD, Gehring K, Maraia RJ. The isolated La-module of LARP1 mediates 3' poly(A) protection and mRNA stabilization, dependent on its intrinsic PAM2 binding to PABPC1. RNA Biol 2021; 18:275-289. [PMID: 33292040 PMCID: PMC7928023 DOI: 10.1080/15476286.2020.1860376] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/18/2022] Open
Abstract
The protein domain arrangement known as the La-module, comprised of a La motif (LaM) followed by a linker and RNA recognition motif (RRM), is found in seven La-related proteins: LARP1, LARP1B, LARP3 (La protein), LARP4, LARP4B, LARP6, and LARP7 in humans. Several LARPs have been characterized for their distinct activity in a specific aspect of RNA metabolism. The La-modules vary among the LARPs in linker length and RRM subtype. The La-modules of La protein and LARP7 bind and protect nuclear RNAs with UUU-3' tails from degradation by 3' exonucleases. LARP4 is an mRNA poly(A) stabilization factor that binds poly(A) and the cytoplasmic poly(A)-binding protein PABPC1 (also known as PABP). LARP1 exhibits poly(A) length protection and mRNA stabilization similar to LARP4. Here, we show that these LARP1 activities are mediated by its La-module and dependent on a PAM2 motif that binds PABP. The isolated La-module of LARP1 is sufficient for PABP-dependent poly(A) length protection and mRNA stabilization in HEK293 cells. A point mutation in the PAM2 motif in the La-module impairs mRNA stabilization and PABP binding in vivo but does not impair oligo(A) RNA binding by the purified recombinant La-module in vitro. We characterize the unusual PAM2 sequence of LARP1 and show it may differentially affect stable and unstable mRNAs. The unique LARP1 La-module can function as an autonomous factor to confer poly(A) protection and stabilization to heterologous mRNAs.
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Affiliation(s)
- Sandy Mattijssen
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Guennadi Kozlov
- Department of Biochemistry & Centre for Structural Biology, McGill University, Montreal, Canada
| | - Sergei Gaidamakov
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | - Amitabh Ranjan
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
| | | | - Kalle Gehring
- Department of Biochemistry & Centre for Structural Biology, McGill University, Montreal, Canada
| | - Richard J. Maraia
- Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, United States
- Commissioned Corps, U.S. Public Health Service, Rockville, MD, USA
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10
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Prats AC, David F, Diallo LH, Roussel E, Tatin F, Garmy-Susini B, Lacazette E. Circular RNA, the Key for Translation. Int J Mol Sci 2020; 21:E8591. [PMID: 33202605 PMCID: PMC7697609 DOI: 10.3390/ijms21228591] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/06/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
It was thought until the 1990s that the eukaryotic translation machinery was unable to translate a circular RNA. However internal ribosome entry sites (IRESs) and m6A-induced ribosome engagement sites (MIRESs) were discovered, promoting 5' end-independent translation initiation. Today a new family of so-called "noncoding" circular RNAs (circRNAs) has emerged, revealing the pivotal role of 5' end-independent translation. CircRNAs have a strong impact on translational control via their sponge function, and form a new mRNA family as they are translated into proteins with pathophysiological roles. While there is no more doubt about translation of covalently closed circRNA, the linearity of canonical mRNA is only theoretical: it has been shown for more than thirty years that polysomes exhibit a circular form and mRNA functional circularization has been demonstrated in the 1990s by the interaction of initiation factor eIF4G with poly(A) binding protein. More recently, additional mechanisms of 3'-5' interaction have been reported, including m6A modification. Functional circularization enhances translation via ribosome recycling and acceleration of the translation initiation rate. This update of covalently and noncovalently closed circular mRNA translation landscape shows that RNA with circular shape might be the rule for translation with an important impact on disease development and biotechnological applications.
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Affiliation(s)
- Anne-Catherine Prats
- Institut des Maladies Métaboliques et Cardiovasculaires, UMR 1048, Inserm, Université de Toulouse UT3, 1, Avenue Jean Poulhes, BP 84225, 31432 Toulouse CEDEX 4, France; (F.D.); (L.H.D.); (E.R.); (F.T.); (B.G.-S.); (E.L.)
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11
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Dock-Bregeon AC, Lewis KA, Conte MR. The La-related proteins: structures and interactions of a versatile superfamily of RNA-binding proteins. RNA Biol 2019; 18:178-193. [PMID: 31752575 DOI: 10.1080/15476286.2019.1695712] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The La-related proteins (LaRPs) are an ancient superfamily of RNA-binding proteins orchestrating the major fates of RNA, from processing and maturation to regulation of mRNA translation. LaRPs are instrumental in modulating complex assemblies where the RNA is bound, folded, processed, escorted and presented to the functional effectors often through recruitment of protein partners. This intricate web of protein-RNA and protein-protein interactions is enabled by the modular nature of the LaRPs, comprising several structured domains connected by flexible linkers, and other sequences lacking recognizable folded motifs. Recent structures, together with biochemical and biophysical studies, have provided insights into how each LaRP family has evolved unique mechanisms of RNA recognition, not only through the conserved RNA-binding unit, the La-module, but also mediated by other family-specific motifs. Furthermore, in a series of unexpected twists and turns, they have revealed that the dynamic and conformational interplay of multi-structured domains and disordered regions operate in unison to achieve RNA substrate discrimination. This review proposes a perspective of our current knowledge of the structure-function relationship of the LaRP superfamily.
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Affiliation(s)
| | - Karen A Lewis
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX, USA
| | - Maria R Conte
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, UK
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12
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The Interactome analysis of the Respiratory Syncytial Virus protein M2-1 suggests a new role in viral mRNA metabolism post-transcription. Sci Rep 2019; 9:15258. [PMID: 31649314 PMCID: PMC6813310 DOI: 10.1038/s41598-019-51746-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/07/2019] [Indexed: 01/18/2023] Open
Abstract
Human respiratory syncytial virus (RSV) is a globally prevalent negative-stranded RNA virus, which can cause life-threatening respiratory infections in young children, elderly people and immunocompromised patients. Its transcription termination factor M2-1 plays an essential role in viral transcription, but the mechanisms underpinning its function are still unclear. We investigated the cellular interactome of M2-1 using green fluorescent protein (GFP)-trap immunoprecipitation on RSV infected cells coupled with mass spectrometry analysis. We identified 137 potential cellular partners of M2-1, among which many proteins associated with mRNA metabolism, and particularly mRNA maturation, translation and stabilization. Among these, the cytoplasmic polyA-binding protein 1 (PABPC1), a candidate with a major role in both translation and mRNA stabilization, was confirmed to interact with M2-1 using protein complementation assay and specific immunoprecipitation. PABPC1 was also shown to colocalize with M2-1 from its accumulation in inclusion bodies associated granules (IBAGs) to its liberation in the cytoplasm. Altogether, these results strongly suggest that M2-1 interacts with viral mRNA and mRNA metabolism factors from transcription to translation, and imply that M2-1 may have an additional role in the fate of viral mRNA downstream of transcription.
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13
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Jankowski S, Pohlmann T, Baumann S, Müntjes K, Devan SK, Zander S, Feldbrügge M. The multi PAM2 protein Upa2 functions as novel core component of endosomal mRNA transport. EMBO Rep 2019; 20:e47381. [PMID: 31338952 PMCID: PMC6726905 DOI: 10.15252/embr.201847381] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 12/28/2022] Open
Abstract
mRNA transport determines spatiotemporal protein expression. Transport units are higher-order ribonucleoprotein complexes containing cargo mRNAs, RNA-binding proteins and accessory proteins. Endosomal mRNA transport in fungal hyphae belongs to the best-studied translocation mechanisms. Although several factors are known, additional core components are missing. Here, we describe the 232 kDa protein Upa2 containing multiple PAM2 motifs (poly[A]-binding protein [Pab1]-associated motif 2) as a novel core component. Loss of Upa2 disturbs transport of cargo mRNAs and associated Pab1. Upa2 is present on almost all transport endosomes in an mRNA-dependent manner. Surprisingly, all four PAM2 motifs are dispensable for function during unipolar hyphal growth. Instead, Upa2 harbours a novel N-terminal effector domain as important functional determinant as well as a C-terminal GWW motif for specific endosomal localisation. In essence, Upa2 meets all the criteria of a novel core component of endosomal mRNA transport and appears to carry out crucial scaffolding functions.
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Affiliation(s)
- Silke Jankowski
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Thomas Pohlmann
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Sebastian Baumann
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
- Present address:
Cell and Developmental BiologyCentre for Genomic Regulation (CRG)BarcelonaSpain
| | - Kira Müntjes
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Senthil Kumar Devan
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Sabrina Zander
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
| | - Michael Feldbrügge
- Institute for MicrobiologyCluster of Excellence on Plant SciencesHeinrich Heine University DüsseldorfDüsseldorfGermany
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14
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Ivanov A, Shuvalova E, Egorova T, Shuvalov A, Sokolova E, Bizyaev N, Shatsky I, Terenin I, Alkalaeva E. Polyadenylate-binding protein-interacting proteins PAIP1 and PAIP2 affect translation termination. J Biol Chem 2019; 294:8630-8639. [PMID: 30992367 DOI: 10.1074/jbc.ra118.006856] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 03/29/2019] [Indexed: 12/29/2022] Open
Abstract
Polyadenylate-binding protein (PABP) stimulates translation termination via interaction of its C-terminal domain with eukaryotic polypeptide chain release factor, eRF3. Additionally, two other proteins, poly(A)-binding protein-interacting proteins 1 and 2 (PAIP1 and PAIP2), bind the same domain of PABP and regulate its translation-related activity. To study the biochemistry of eRF3 and PAIP1/2 competition for PABP binding, we quantified the effects of PAIPs on translation termination in the presence or absence of PABP. Our results demonstrated that both PAIP1 and PAIP2 prevented translation termination at the premature termination codon, by controlling PABP activity. Moreover, PAIP1 and PAIP2 inhibited the activity of free PABP on translation termination in vitro However, after binding the poly(A) tail, PABP became insensitive to suppression by PAIPs and efficiently activated translation termination in the presence of eRF3a. Additionally, we revealed that PAIP1 binds eRF3 in solution, which stabilizes the post-termination complex. These results indicated that PAIP1 and PAIP2 participate in translation termination and are important regulators of readthrough at the premature termination codon.
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Affiliation(s)
- Alexandr Ivanov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia; Faculty of Bioengineering and Bioinformatics, M. V. Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ekaterina Shuvalova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Tatiana Egorova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Alexey Shuvalov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Elizaveta Sokolova
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Nikita Bizyaev
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia
| | - Ivan Shatsky
- Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow 119234, Russia
| | - Ilya Terenin
- Belozersky Institute of Physico-Chemical Biology, M. V. Lomonosov Moscow State University, Moscow 119234, Russia; Sechenov First Moscow State Medical University, Institute of Molecular Medicine, Moscow 119146, Russia.
| | - Elena Alkalaeva
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow 119991, Russia.
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15
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Hellen CUT. Translation Termination and Ribosome Recycling in Eukaryotes. Cold Spring Harb Perspect Biol 2018; 10:cshperspect.a032656. [PMID: 29735640 DOI: 10.1101/cshperspect.a032656] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Termination of mRNA translation occurs when a stop codon enters the A site of the ribosome, and in eukaryotes is mediated by release factors eRF1 and eRF3, which form a ternary eRF1/eRF3-guanosine triphosphate (GTP) complex. eRF1 recognizes the stop codon, and after hydrolysis of GTP by eRF3, mediates release of the nascent peptide. The post-termination complex is then disassembled, enabling its constituents to participate in further rounds of translation. Ribosome recycling involves splitting of the 80S ribosome by the ATP-binding cassette protein ABCE1 to release the 60S subunit. Subsequent dissociation of deacylated transfer RNA (tRNA) and messenger RNA (mRNA) from the 40S subunit may be mediated by initiation factors (priming the 40S subunit for initiation), by ligatin (eIF2D) or by density-regulated protein (DENR) and multiple copies in T-cell lymphoma-1 (MCT1). These events may be subverted by suppression of termination (yielding carboxy-terminally extended read-through polypeptides) or by interruption of recycling, leading to reinitiation of translation near the stop codon.
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Affiliation(s)
- Christopher U T Hellen
- Department of Cell Biology, State University of New York, Downstate Medical Center, New York, New York 11203
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16
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New insights into the interplay between the translation machinery and nonsense-mediated mRNA decay factors. Biochem Soc Trans 2018; 46:503-512. [PMID: 29626148 PMCID: PMC6008592 DOI: 10.1042/bst20170427] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 12/13/2022]
Abstract
Faulty mRNAs with a premature stop codon (PTC) are recognized and degraded by nonsense-mediated mRNA decay (NMD). Recognition of a nonsense mRNA depends on translation and on the presence of NMD-enhancing or the absence of NMD-inhibiting factors in the 3'-untranslated region. Our review summarizes our current understanding of the molecular function of the conserved NMD factors UPF3B and UPF1, and of the anti-NMD factor Poly(A)-binding protein, and their interactions with ribosomes translating PTC-containing mRNAs. Our recent discovery that UPF3B interferes with human translation termination and enhances ribosome dissociation in vitro, whereas UPF1 is inactive in these assays, suggests a re-interpretation of previous experiments and modification of prevalent NMD models. Moreover, we discuss recent work suggesting new functions of the key NMD factor UPF1 in ribosome recycling, inhibition of translation re-initiation and nascent chain ubiquitylation. These new findings suggest that the interplay of UPF proteins with the translation machinery is more intricate than previously appreciated, and that this interplay quality-controls the efficiency of termination, ribosome recycling and translation re-initiation.
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17
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de Melo Neto OP, da Costa Lima TDC, Merlo KC, Romão TP, Rocha PO, Assis LA, Nascimento LM, Xavier CC, Rezende AM, Reis CRS, Papadopoulou B. Phosphorylation and interactions associated with the control of the Leishmania Poly-A Binding Protein 1 (PABP1) function during translation initiation. RNA Biol 2018; 15:739-755. [PMID: 29569995 DOI: 10.1080/15476286.2018.1445958] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Poly-A Binding Protein (PABP) is a conserved eukaryotic polypeptide involved in many aspects of mRNA metabolism. During translation initiation, PABP interacts with the translation initiation complex eIF4F and enhances the translation of polyadenylated mRNAs. Schematically, most PABPs can be divided into an N-terminal RNA-binding region, a non-conserved linker segment and the C-terminal MLLE domain. In pathogenic Leishmania protozoans, three PABP homologues have been identified, with the first one (PABP1) targeted by phosphorylation and shown to co-immunoprecipitate with an eIF4F-like complex (EIF4E4/EIF4G3) implicated in translation initiation. Here, PABP1 phosphorylation was shown to be linked to logarithmic cell growth, reminiscent of EIF4E4 phosphorylation, and coincides with polysomal association. Phosphorylation targets multiple serine-proline (SP) or threonine-proline (TP) residues within the PABP1 linker region. This is an essential protein, but phosphorylation is not needed for its association with polysomes or cell viability. Mutations which do impair PABP1 polysomal association and are required for viability do not prevent phosphorylation, although further mutations lead to a presumed inactive protein largely lacking phosphorylated isoforms. Co-immunoprecipitation experiments were carried out to investigate PABP1 function further, identifying several novel protein partners and the EIF4E4/EIF4G3 complex, but no other eIF4F-like complex or subunit. A novel, direct interaction between PABP1 and EIF4E4 was also investigated and found to be mediated by the PABP1 MLLE binding to PABP Interacting Motifs (PAM2) within the EIF4E4 N-terminus. The results shown here are consistent with phosphorylation of PABP1 being part of a novel pathway controlling its function and possibly translation in Leishmania.
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Affiliation(s)
| | | | - Kleison C Merlo
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | - Tatiany P Romão
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | - Ludmila A Assis
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | - Camila C Xavier
- a Instituto Aggeu Magalhães - FIOCRUZ , Recife , PE , Brazil
| | | | | | - Barbara Papadopoulou
- c CHU de Quebec Research Center and Department of Microbiology-Infectious Disease and Immunology , Laval University , Quebec , QC , Canada
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18
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Sawazaki R, Imai S, Yokogawa M, Hosoda N, Hoshino SI, Mio M, Mio K, Shimada I, Osawa M. Characterization of the multimeric structure of poly(A)-binding protein on a poly(A) tail. Sci Rep 2018; 8:1455. [PMID: 29362417 PMCID: PMC5780489 DOI: 10.1038/s41598-018-19659-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 01/05/2018] [Indexed: 11/24/2022] Open
Abstract
Eukaryotic mature mRNAs possess a poly adenylate tail (poly(A)), to which multiple molecules of poly(A)-binding protein C1 (PABPC1) bind. PABPC1 regulates translation and mRNA metabolism by binding to regulatory proteins. To understand functional mechanism of the regulatory proteins, it is necessary to reveal how multiple molecules of PABPC1 exist on poly(A). Here, we characterize the structure of the multiple molecules of PABPC1 on poly(A), by using transmission electron microscopy (TEM), chemical cross-linking, and NMR spectroscopy. The TEM images and chemical cross-linking results indicate that multiple PABPC1 molecules form a wormlike structure in the PABPC1-poly(A) complex, in which the PABPC1 molecules are linearly arrayed. NMR and cross-linking analyses indicate that PABPC1 forms a multimer by binding to the neighbouring PABPC1 molecules via interactions between the RNA recognition motif (RRM) 2 in one molecule and the middle portion of the linker region of another molecule. A PABPC1 mutant lacking the interaction site in the linker, which possesses an impaired ability to form the multimer, reduced the in vitro translation activity, suggesting the importance of PABPC1 multimer formation in the translation process. We therefore propose a model of the PABPC1 multimer that provides clues to comprehensively understand the regulation mechanism of mRNA translation.
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Affiliation(s)
- Ryoichi Sawazaki
- Graduate School of Pharmaceutical Sciences, Keio University, Shibakoen, Minato-ku, Tokyo, 105-8512, Japan
| | - Shunsuke Imai
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Mariko Yokogawa
- Graduate School of Pharmaceutical Sciences, Keio University, Shibakoen, Minato-ku, Tokyo, 105-8512, Japan
| | - Nao Hosoda
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan
| | - Shin-Ichi Hoshino
- Graduate School of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan
| | - Muneyo Mio
- Molecular Profiling Research Center for Drug Discovery and OPERANDO Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo, 135-0064, Japan
| | - Kazuhiro Mio
- Molecular Profiling Research Center for Drug Discovery and OPERANDO Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo, 135-0064, Japan
| | - Ichio Shimada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masanori Osawa
- Graduate School of Pharmaceutical Sciences, Keio University, Shibakoen, Minato-ku, Tokyo, 105-8512, Japan. .,Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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19
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Niessing D, Jansen RP, Pohlmann T, Feldbrügge M. mRNA transport in fungal top models. WILEY INTERDISCIPLINARY REVIEWS-RNA 2017; 9. [PMID: 28994236 DOI: 10.1002/wrna.1453] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 08/28/2017] [Accepted: 09/05/2017] [Indexed: 01/13/2023]
Abstract
Eukaryotic cells rely on the precise determination of when and where proteins are synthesized. Spatiotemporal expression is supported by localization of mRNAs to specific subcellular sites and their subsequent local translation. This holds true for somatic cells as well as for oocytes and embryos. Most commonly, mRNA localization is achieved by active transport of the molecules along the actin or microtubule cytoskeleton. Key factors are molecular motors, adaptors, and RNA-binding proteins that recognize defined sequences or structures in cargo mRNAs. A deep understanding of this process has been gained from research on fungal model systems such as Saccharomyces cerevisiae and Ustilago maydis. Recent highlights of these studies are the following: (1) synergistic binding of two RNA-binding proteins is needed for high affinity recognition; (2) RNA sequences undergo profound structural rearrangements upon recognition; (3) mRNA transport is tightly linked to membrane trafficking; (4) mRNAs and ribosomes are transported on the cytoplasmic surface of endosomes; and (5) heteromeric protein complexes are, most likely, assembled co-translationally during endosomal transport. Thus, the study of simple fungal model organisms provides valuable insights into fundamental mechanisms of mRNA transport boosting the understanding of similar events in higher eukaryotes. WIREs RNA 2018, 9:e1453. doi: 10.1002/wrna.1453 This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization.
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Affiliation(s)
- Dierk Niessing
- Department of Cell Biology, Biomedical Center, Ludwig-Maximilians-University München, Planegg-Martinsried, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Ralf-Peter Jansen
- Interfaculty Institute of Biochemistry, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Thomas Pohlmann
- Centre of Excellence on Plant Sciences, Institute for Microbiology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
| | - Michael Feldbrügge
- Centre of Excellence on Plant Sciences, Institute for Microbiology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany
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20
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Fatscher T, Gehring NH. Harnessing short poly(A)-binding protein-interacting peptides for the suppression of nonsense-mediated mRNA decay. Sci Rep 2016; 6:37311. [PMID: 27874031 PMCID: PMC5118804 DOI: 10.1038/srep37311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/27/2016] [Indexed: 11/17/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a cellular process that eliminates messenger RNA (mRNA) substrates with premature translation termination codons (PTCs). In addition, NMD regulates the expression of a number of physiological mRNAs, for example transcripts containing long 3′ UTRs. Current models implicate the interaction between cytoplasmic poly(A)-binding protein (PABPC1) and translation termination in NMD. Accordingly, PABPC1 present within close proximity of a termination codon antagonizes NMD. Here, we use reporter mRNAs with different NMD-inducing 3′ UTRs to establish a general NMD-inhibiting property of PABPC1. NMD-inhibition is not limited to PABPC1, but can also be achieved by peptides consisting of the PABP-interacting motif 2 (PAM2) of different proteins when recruited to an NMD-inhibiting position of NMD reporter transcripts. The short PAM2 peptides efficiently suppress NMD activated by a long 3′ UTR, an exon-junction complex (EJC) and individual EJC components, and stabilize a PTC-containing β-globin mRNA. In conclusion, our results establish short PABPC1-recruiting peptides as potent but position-dependent inhibitors of mammalian NMD.
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Affiliation(s)
- Tobias Fatscher
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, Cologne, Germany
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21
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Ivanov A, Mikhailova T, Eliseev B, Yeramala L, Sokolova E, Susorov D, Shuvalov A, Schaffitzel C, Alkalaeva E. PABP enhances release factor recruitment and stop codon recognition during translation termination. Nucleic Acids Res 2016; 44:7766-76. [PMID: 27418677 PMCID: PMC5027505 DOI: 10.1093/nar/gkw635] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 07/01/2016] [Indexed: 01/01/2023] Open
Abstract
Poly(A)-binding protein (PABP) is a major component of the messenger RNA–protein complex. PABP is able to bind the poly(A) tail of mRNA, as well as translation initiation factor 4G and eukaryotic release factor 3a (eRF3a). PABP has been found to stimulate translation initiation and to inhibit nonsense-mediated mRNA decay. Using a reconstituted mammalian in vitro translation system, we show that PABP directly stimulates translation termination. PABP increases the efficiency of translation termination by recruitment of eRF3a and eRF1 to the ribosome. PABP's function in translation termination depends on its C-terminal domain and its interaction with the N-terminus of eRF3a. Interestingly, we discover that full-length eRF3a exerts a different mode of function compared to its truncated form eRF3c, which lacks the N-terminal domain. Pre-association of eRF3a, but not of eRF3c, with pre-termination complexes (preTCs) significantly increases the efficiency of peptidyl–tRNA hydrolysis by eRF1. This implicates new, additional interactions of full-length eRF3a with the ribosomal preTC. Based on our findings, we suggest that PABP enhances the productive binding of the eRF1–eRF3 complex to the ribosome, via interactions with the N-terminal domain of eRF3a which itself has an active role in translation termination.
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Affiliation(s)
- Alexandr Ivanov
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia Faculty of Bioengineering and Bioinformatics, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Tatyana Mikhailova
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Boris Eliseev
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Lahari Yeramala
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Elizaveta Sokolova
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Denis Susorov
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia Faculty of Bioengineering and Bioinformatics, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Alexey Shuvalov
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Christiane Schaffitzel
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France School of Biochemistry, University of Bristol, BS8 1TD, UK
| | - Elena Alkalaeva
- Engelhardt Institute of Molecular Biology, the Russian Academy of Sciences, 119991 Moscow, Russia
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22
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Jerbi S, Jolles B, Bouceba T, Jean-Jean O. Studies on human eRF3-PABP interaction reveal the influence of eRF3a N-terminal glycin repeat on eRF3-PABP binding affinity and the lower affinity of eRF3a 12-GGC allele involved in cancer susceptibility. RNA Biol 2016; 13:306-15. [PMID: 26818177 PMCID: PMC4829321 DOI: 10.1080/15476286.2015.1137421] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The eukaryotic release factor 3 (eRF3) has been involved in the control of mRNA degradation through its association with the cytoplasmic Poly(A) Binding Protein, PABP. In mammals, eRF3 N-terminal domain contains two overlapping PAM2 motifs which specifically recognize the MLLE domain of PABP. In humans, eRF3a/GSPT1 gene contains a stable GGC repeat encoding a repeat of glycine residues in eRF3a N-terminus. There are five known eRF3a/GSPT1 alleles in the human population, encoding 7, 9, 10, 11 and 12 glycines. Several studies have reported that the presence of eRF3a 12-GGC allele is correlated with an increased risk of cancer development. Using surface plasmon resonance, we have studied the interaction of the various allelic forms of eRF3a with PABP alone or poly(A)-bound PABP. We found that the N-terminal glycine repeat of eRF3a influences eRF3a-PABP interaction and that eRF3a 12-GGC allele has a decreased binding affinity for PABP. Our comparative analysis on eRF3a alleles suggests that the presence of eRF3a 12-GGC allele could modify the coupling between translation termination and mRNA deadenylation.
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Affiliation(s)
- Soumaya Jerbi
- a Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris-Seine (IBPS), CNRS-UMR8256 , 7 quai Saint Bernard, Paris , France
| | - Béatrice Jolles
- a Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris-Seine (IBPS), CNRS-UMR8256 , 7 quai Saint Bernard, Paris , France
| | - Tahar Bouceba
- b Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris-Seine (IBPS), CNRS-FR3631 , 7 quai Saint Bernard, Paris , France
| | - Olivier Jean-Jean
- a Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris-Seine (IBPS), CNRS-UMR8256 , 7 quai Saint Bernard, Paris , France
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Ajiro M, Jia R, Yang Y, Zhu J, Zheng ZM. A genome landscape of SRSF3-regulated splicing events and gene expression in human osteosarcoma U2OS cells. Nucleic Acids Res 2015; 44:1854-70. [PMID: 26704980 PMCID: PMC4770227 DOI: 10.1093/nar/gkv1500] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 12/11/2015] [Indexed: 02/07/2023] Open
Abstract
Alternative RNA splicing is an essential process to yield proteomic diversity in eukaryotic cells, and aberrant splicing is often associated with numerous human diseases and cancers. We recently described serine/arginine-rich splicing factor 3 (SRSF3 or SRp20) being a proto-oncogene. However, the SRSF3-regulated splicing events responsible for its oncogenic activities remain largely unknown. By global profiling of the SRSF3-regulated splicing events in human osteosarcoma U2OS cells, we found that SRSF3 regulates the expression of 60 genes including ERRFI1, ANXA1 and TGFB2, and 182 splicing events in 164 genes, including EP300, PUS3, CLINT1, PKP4, KIF23, CHK1, SMC2, CKLF, MAP4, MBNL1, MELK, DDX5, PABPC1, MAP4K4, Sp1 and SRSF1, which are primarily associated with cell proliferation or cell cycle. Two SRSF3-binding motifs, CCAGC(G)C and A(G)CAGCA, are enriched to the alternative exons. An SRSF3-binding site in the EP300 exon 14 is essential for exon 14 inclusion. We found that the expression of SRSF1 and SRSF3 are mutually dependent and coexpressed in normal and tumor tissues/cells. SRSF3 also significantly regulates the expression of at least 20 miRNAs, including a subset of oncogenic or tumor suppressive miRNAs. These data indicate that SRSF3 affects a global change of gene expression to maintain cell homeostasis.
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Affiliation(s)
- Masahiko Ajiro
- Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Rong Jia
- Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
| | - Yanqin Yang
- DNA Sequencing and Genomics Core, System Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jun Zhu
- DNA Sequencing and Genomics Core, System Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Zhi-Ming Zheng
- Tumor Virus RNA Biology Section, Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA
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Fatscher T, Boehm V, Gehring NH. Mechanism, factors, and physiological role of nonsense-mediated mRNA decay. Cell Mol Life Sci 2015; 72:4523-44. [PMID: 26283621 PMCID: PMC11113733 DOI: 10.1007/s00018-015-2017-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/10/2015] [Accepted: 08/06/2015] [Indexed: 02/04/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a translation-dependent, multistep process that degrades irregular or faulty messenger RNAs (mRNAs). NMD mainly targets mRNAs with a truncated open reading frame (ORF) due to premature termination codons (PTCs). In addition, NMD also regulates the expression of different types of endogenous mRNA substrates. A multitude of factors are involved in the tight regulation of the NMD mechanism. In this review, we focus on the molecular mechanism of mammalian NMD. Based on the published data, we discuss the involvement of translation termination in NMD initiation. Furthermore, we provide a detailed overview of the core NMD machinery, as well as several peripheral NMD factors, and discuss their function. Finally, we present an overview of diseases associated with NMD factor mutations and summarize the current state of treatment for genetic disorders caused by nonsense mutations.
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Affiliation(s)
- Tobias Fatscher
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Volker Boehm
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, Cologne, Germany.
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Target Discrimination in Nonsense-Mediated mRNA Decay Requires Upf1 ATPase Activity. Mol Cell 2015; 59:413-25. [PMID: 26253027 DOI: 10.1016/j.molcel.2015.06.036] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/27/2015] [Accepted: 06/29/2015] [Indexed: 12/17/2022]
Abstract
RNA quality-control pathways get rid of faulty RNAs and therefore must be able to discriminate these RNAs from those that are normal. Here we present evidence that the adenosine triphosphatase (ATPase) cycle of the SF1 helicase Upf1 is required for mRNA discrimination during nonsense-mediated decay (NMD). Mutations affecting the Upf1 ATPase cycle disrupt the mRNA selectivity of Upf1, leading to indiscriminate accumulation of NMD complexes on both NMD target and non-target mRNAs. In addition, two modulators of NMD-translation and termination codon-proximal poly(A) binding protein-depend on the ATPase activity of Upf1 to limit Upf1-non-target association. Preferential ATPase-dependent dissociation of Upf1 from non-target mRNAs in vitro suggests that selective release of Upf1 contributes to the ATPase dependence of Upf1 target discrimination. Given the prevalence of helicases in RNA regulation, ATP hydrolysis may be a widely used activity in target RNA discrimination.
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Lykke-Andersen S, Jensen TH. Nonsense-mediated mRNA decay: an intricate machinery that shapes transcriptomes. Nat Rev Mol Cell Biol 2015; 16:665-77. [PMID: 26397022 DOI: 10.1038/nrm4063] [Citation(s) in RCA: 522] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is probably the best characterized eukaryotic RNA degradation pathway. Through intricate steps, a set of NMD factors recognize and degrade mRNAs with translation termination codons that are positioned in abnormal contexts. However, NMD is not only part of a general cellular quality control system that prevents the production of aberrant proteins. Mammalian cells also depend on NMD to dynamically adjust their transcriptomes and their proteomes to varying physiological conditions. In this Review, we discuss how NMD targets mRNAs, the types of mRNAs that are targeted, and the roles of NMD in cellular stress, differentiation and maturation processes.
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Affiliation(s)
- Søren Lykke-Andersen
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
| | - Torben Heick Jensen
- Centre for mRNP Biogenesis and Metabolism, Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark
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27
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Roque S, Cerciat M, Gaugué I, Mora L, Floch AG, de Zamaroczy M, Heurgué-Hamard V, Kervestin S. Interaction between the poly(A)-binding protein Pab1 and the eukaryotic release factor eRF3 regulates translation termination but not mRNA decay in Saccharomyces cerevisiae. RNA (NEW YORK, N.Y.) 2015; 21:124-134. [PMID: 25411355 PMCID: PMC4274632 DOI: 10.1261/rna.047282.114] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/26/2014] [Indexed: 06/04/2023]
Abstract
Eukaryotic release factor 3 (eRF3) is implicated in translation termination and also interacts with the poly(A)-binding protein (PABP, Pab1 in yeast), a major player in mRNA metabolism. Despite conservation of this interaction, its precise function remains elusive. First, we showed experimentally that yeast eRF3 does not contain any obvious consensus PAM2 (PABP-interacting motif 2). Thus, in yeast this association is different from the well described interaction between the metazoan factors. To gain insight into the exact function of this interaction, we then analyzed the phenotypes resulting from deleting the respective binding domains. Deletion of the Pab1 interaction domain on eRF3 did not affect general mRNA stability or nonsense-mediated mRNA decay (NMD) pathway and induced a decrease in translational readthrough. Furthermore, combined deletions of the respective interacting domains on eRF3 and on Pab1 were viable, did not affect Pab1 function in mRNA stability and harbored an antisuppression phenotype. Our results show that in Saccharomyces cerevisiae the role of the Pab1 C-terminal domain in mRNA stability is independent of eRF3 and the association of these two factors negatively regulates translation termination.
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Affiliation(s)
- Sylvain Roque
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Marie Cerciat
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Isabelle Gaugué
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Liliana Mora
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Aurélie G Floch
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Miklos de Zamaroczy
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Valérie Heurgué-Hamard
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France
| | - Stephanie Kervestin
- CNRS FRE3630 (affiliated with Université Paris Diderot, Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris 75005, France Metabolism and function of RNA in the nucleus, Institut Jacques Monod, CNRS UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris 75013, France
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Fatscher T, Boehm V, Weiche B, Gehring NH. The interaction of cytoplasmic poly(A)-binding protein with eukaryotic initiation factor 4G suppresses nonsense-mediated mRNA decay. RNA (NEW YORK, N.Y.) 2014; 20:1579-92. [PMID: 25147240 PMCID: PMC4174440 DOI: 10.1261/rna.044933.114] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) eliminates different classes of mRNA substrates including transcripts with long 3' UTRs. Current models of NMD suggest that the long physical distance between the poly(A) tail and the termination codon reduces the interaction between cytoplasmic poly(A)-binding protein (PABPC1) and the eukaryotic release factor 3a (eRF3a) during translation termination. In the absence of PABPC1 binding, eRF3a recruits the NMD factor UPF1 to the terminating ribosome, triggering mRNA degradation. Here, we have used the MS2 tethering system to investigate the suppression of NMD by PABPC1. We show that tethering of PABPC1 between the termination codon and a long 3' UTR specifically inhibits NMD-mediated mRNA degradation. Contrary to the current model, tethered PABPC1 mutants unable to interact with eRF3a still efficiently suppress NMD. We find that the interaction of PABPC1 with eukaryotic initiation factor 4G (eIF4G), which mediates the circularization of mRNAs, is essential for NMD inhibition by tethered PABPC1. Furthermore, recruiting either eRF3a or eIF4G in proximity to an upstream termination codon antagonizes NMD. While tethering of an eRF3a mutant unable to interact with PABPC1 fails to suppress NMD, tethered eIF4G inhibits NMD in a PABPC1-independent manner, indicating a sequential arrangement of NMD antagonizing factors. In conclusion, our results establish a previously unrecognized link between translation termination, mRNA circularization, and NMD suppression, thereby suggesting a revised model for the activation of NMD at termination codons upstream of long 3' UTR.
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Affiliation(s)
- Tobias Fatscher
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Volker Boehm
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Benjamin Weiche
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, 50674 Cologne, Germany
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Joncourt R, Eberle AB, Rufener SC, Mühlemann O. Eukaryotic initiation factor 4G suppresses nonsense-mediated mRNA decay by two genetically separable mechanisms. PLoS One 2014; 9:e104391. [PMID: 25148142 PMCID: PMC4141738 DOI: 10.1371/journal.pone.0104391] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/08/2014] [Indexed: 11/19/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD), which is best known for degrading mRNAs with premature termination codons (PTCs), is thought to be triggered by aberrant translation termination at stop codons located in an environment of the mRNP that is devoid of signals necessary for proper termination. In mammals, the cytoplasmic poly(A)-binding protein 1 (PABPC1) has been reported to promote correct termination and therewith antagonize NMD by interacting with the eukaryotic release factors 1 (eRF1) and 3 (eRF3). Using tethering assays in which proteins of interest are recruited as MS2 fusions to a NMD reporter transcript, we show that the three N-terminal RNA recognition motifs (RRMs) of PABPC1 are sufficient to antagonize NMD, while the eRF3-interacting C-terminal domain is dispensable. The RRM1-3 portion of PABPC1 interacts with eukaryotic initiation factor 4G (eIF4G) and tethering of eIF4G to the NMD reporter also suppresses NMD. We identified the interactions of the eIF4G N-terminus with PABPC1 and the eIF4G core domain with eIF3 as two genetically separable features that independently enable tethered eIF4G to inhibit NMD. Collectively, our results reveal a function of PABPC1, eIF4G and eIF3 in translation termination and NMD suppression, and they provide additional evidence for a tight coupling between translation termination and initiation.
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Affiliation(s)
- Raphael Joncourt
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Andrea B. Eberle
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
| | - Simone C. Rufener
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Oliver Mühlemann
- University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland
- * E-mail:
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The "tale" of poly(A) binding protein: the MLLE domain and PAM2-containing proteins. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:1062-8. [PMID: 25120199 DOI: 10.1016/j.bbagrm.2014.08.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 07/11/2014] [Accepted: 08/04/2014] [Indexed: 11/21/2022]
Abstract
The cytoplasmic poly(A) binding protein 1 (PABPC1) is an essential eukaryotic translational initiation factor first described over 40 years ago. Most studies of PABPC1 have focused on its N-terminal RRM domains, which bind the mRNA 3' poly(A) tail and 5' translation complex eIF4F via eIF4G; however, the protein also contains a C-terminal MLLE domain that binds a peptide motif, termed PAM2, found in many proteins involved in translation regulation and mRNA metabolism. Studies over the past decade have revealed additional functions of PAM2-containing proteins (PACs) in neurodegenerative diseases, circadian rhythms, innate defense, and ubiquitin-mediated protein degradation. Here, we summarize functional and structural studies of the MLLE/PAM2 interaction and discuss the diverse roles of PACs.
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Jiménez-López D, Guzmán P. Insights into the evolution and domain structure of Ataxin-2 proteins across eukaryotes. BMC Res Notes 2014; 7:453. [PMID: 25027299 PMCID: PMC4105795 DOI: 10.1186/1756-0500-7-453] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 07/03/2014] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Ataxin-2 is an evolutionarily conserved protein first identified in humans as responsible for spinocerebellar ataxia type 2 (SCA2). The molecular basis of SCA2 is the expansion of a polyglutamine tract in Ataxin-2, encoding a Lsm domain that may bind RNA and a PAM2 motif that enables interaction with the poly (A) binding protein. Although the association with SCA2 has been verified, a detailed molecular function for Ataxin-2 has not been established. RESULTS We have undertaken a survey of Ataxin-2 proteins across all eukaryotic domains. In eukaryotes, except for vertebrates and land plants, a single ortholog was identified. Notably, with the exception of birds, two Ataxin-2 genes exist in vertebrates. Expansion was observed in land plants and a novel class lacking the LsmAD domain was identified. Large polyQ tracts appear limited to primates and insects of the orders Hymenoptera and Diptera. A common feature across Ataxin-2 orthologs is the presence of proline-rich motifs, formerly described in the human protein. CONCLUSION Our analysis provides valuable information on the evolution and domain structure of Ataxin-2 proteins. Proline-rich motifs that may mediate protein interactions are widespread in Ataxin-2 proteins, but expansion of polyglutamine tracts associated with spinocerebellar ataxia type 2, is present only in primates, as well as some insects. Our analysis of Ataxin-2 proteins provides also a source to examine orthologs in a number of different species.
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Affiliation(s)
- Domingo Jiménez-López
- Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados, Unidad Irapuato, Apartado Postal 629, Irapuato, Gto 36821, México
| | - Plinio Guzmán
- Departamento de Ingeniería Genética, Centro de Investigación y de Estudios Avanzados, Unidad Irapuato, Apartado Postal 629, Irapuato, Gto 36821, México
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Huang KL, Chadee AB, Chen CYA, Zhang Y, Shyu AB. Phosphorylation at intrinsically disordered regions of PAM2 motif-containing proteins modulates their interactions with PABPC1 and influences mRNA fate. RNA (NEW YORK, N.Y.) 2013; 19:295-305. [PMID: 23340509 PMCID: PMC3677241 DOI: 10.1261/rna.037317.112] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cytoplasmic poly(A)-binding protein (PABP) C1 recruits different interacting partners to regulate mRNA fate. The majority of PABP-interacting proteins contain a PAM2 motif to mediate their interactions with PABPC1. However, little is known about the regulation of these interactions or the corresponding functional consequences. Through in silico analysis, we found that PAM2 motifs are generally embedded within an extended intrinsic disorder region (IDR) and are located next to cluster(s) of potential serine (Ser) or threonine (Thr) phosphorylation sites within the IDR. We hypothesized that phosphorylation at these Ser/Thr sites regulates the interactions between PAM2-containing proteins and PABPC1. In the present study, we have tested this hypothesis using complementary approaches to increase or decrease phosphorylation. The results indicate that changing the extent of phosphorylation of three PAM2-containing proteins (Tob2, Pan3, and Tnrc6c) alters their ability to interact with PABPC1. Results from experiments using phospho-blocking or phosphomimetic mutants in PAM2-containing proteins further support our hypothesis. Moreover, the phosphomimetic mutations appreciably affected the functions of these proteins in mRNA turnover and gene silencing. Taken together, these results provide a new framework for understanding the roles of intrinsically disordered proteins in the dynamic and signal-dependent control of cytoplasmic mRNA functions.
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Schweingruber C, Rufener SC, Zünd D, Yamashita A, Mühlemann O. Nonsense-mediated mRNA decay - mechanisms of substrate mRNA recognition and degradation in mammalian cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:612-23. [PMID: 23435113 DOI: 10.1016/j.bbagrm.2013.02.005] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 02/10/2013] [Accepted: 02/12/2013] [Indexed: 12/15/2022]
Abstract
The nonsense-mediated mRNA decay (NMD) pathway is well known as a translation-coupled quality control system that recognizes and degrades aberrant mRNAs with truncated open reading frames (ORF) due to the presence of a premature termination codon (PTC). However, a more general role of NMD in posttranscriptional regulation of gene expression is indicated by transcriptome-wide mRNA profilings that identified a plethora of physiological mRNAs as NMD targets. In this review, we focus on mechanistic aspects of target mRNA identification and degradation in mammalian cells, based on the available biochemical and genetic data, and point out knowledge gaps. Translation termination in a messenger ribonucleoprotein particle (mRNP) environment lacking necessary factors for proper translation termination emerges as a key determinant for subjecting an mRNA to NMD, and we therefore review recent structural and mechanistic insight into translation termination. In addition, the central role of UPF1, its crucial phosphorylation/dephosphorylation cycle and dynamic interactions with other NMD factors are discussed. Moreover, we address the role of exon junction complexes (EJCs) in NMD and summarize the functions of SMG5, SMG6 and SMG7 in promoting mRNA decay through different routes. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Yamashita A. Role of SMG-1-mediated Upf1 phosphorylation in mammalian nonsense-mediated mRNA decay. Genes Cells 2013; 18:161-75. [DOI: 10.1111/gtc.12033] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 12/06/2012] [Indexed: 12/14/2022]
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Osawa M, Hosoda N, Nakanishi T, Uchida N, Kimura T, Imai S, Machiyama A, Katada T, Hoshino SI, Shimada I. Biological role of the two overlapping poly(A)-binding protein interacting motifs 2 (PAM2) of eukaryotic releasing factor eRF3 in mRNA decay. RNA (NEW YORK, N.Y.) 2012; 18:1957-67. [PMID: 23019593 PMCID: PMC3479387 DOI: 10.1261/rna.035311.112] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 07/31/2012] [Indexed: 05/18/2023]
Abstract
Eukaryotic releasing factor GSPT/eRF3 mediates translation termination-coupled mRNA decay via interaction with a cytosolic poly(A)-binding protein (PABPC1). A region of eRF3 containing two overlapping PAM2 (PABPC1-interacting motif 2) motifs is assumed to bind to the PABC domain of PABPC1, on the poly(A) tail of mRNA. PAM2 motifs are also found in the major deadenylases Caf1-Ccr4 and Pan2-Pan3, whose activities are enhanced upon PABPC1 binding to these motifs. Their deadenylase activities are regulated by eRF3, in which two overlapping PAM2 motifs competitively prevent interaction with PABPC1. However, it is unclear how these overlapping motifs recognize PABC and regulate deadenylase activity in a translation termination-coupled manner. We used a dominant-negative approach to demonstrate that the N-terminal PAM2 motif is critical for eRF3 binding to PABPC1 and that both motifs are required for function. Isothermal titration calorimetry (ITC) and NMR analyses revealed that the interaction is in equilibrium between the two PAM2-PABC complexes, where only one of the two overlapping PAM2 motifs is PABC-bound and the other is PABC-unbound and partially accessible to the other PABC. Based on these results, we proposed a biological role for the overlapping PAM2 motifs in the regulation of deadenylase accessibility to PABPC1 at the 3' end of poly(A).
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Affiliation(s)
- Masanori Osawa
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Nao Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Tamiji Nakanishi
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Naoyuki Uchida
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tomomi Kimura
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shunsuke Imai
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Asako Machiyama
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shin-ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Ichio Shimada
- Department of Physical Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
- Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo 135-0064, Japan
- Corresponding authorE-mail
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Interplay between polyadenylate-binding protein 1 and Kaposi's sarcoma-associated herpesvirus ORF57 in accumulation of polyadenylated nuclear RNA, a viral long noncoding RNA. J Virol 2012; 87:243-56. [PMID: 23077296 DOI: 10.1128/jvi.01693-12] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Polyadenylate-binding protein cytoplasmic 1 (PABPC1) is a cytoplasmic-nuclear shuttling protein important for protein translation initiation and both RNA processing and stability. We report that PABPC1 forms a complex with the Kaposi's sarcoma-associated herpesvirus (KSHV) ORF57 protein, which allows ORF57 to interact with a 9-nucleotide (nt) core element of KSHV polyadenylated nuclear (PAN) RNA, a viral long noncoding RNA (lncRNA), and increase PAN stability. The N-terminal RNA recognition motifs (RRMs) of PABPC1 are necessary for the direct interaction with ORF57. During KSHV lytic infection, the expression of viral ORF57 leads to a substantial decrease in overall PABPC1 expression, along with a shift in the cellular distribution of the remaining PABPC1 to the nucleus. Interestingly, PABPC1 and ORF57 have opposing functions in modulating PAN steady-state accumulation. The suppressive effect of PABPC1 specific to PAN expression is alleviated by small interfering RNA knockdown of PABPC1 or by overexpression of ORF57. Conversely, ectopic PABPC1 reduces ORF57 steady-state protein levels and induces aberrant polyadenylation of PAN and thereby indirectly inhibits ORF57-mediated PAN accumulation. However, E1B-AP5 (heterogeneous nuclear ribonucleoprotein U-like 1), which interacts with a region outside the 9-nt core to stimulate PAN expression, does not interact or even colocalize with ORF57. Unlike PABPC1, the nuclear distribution of E1B-AP5 remains unchanged by viral lytic infection or overexpression of ORF57. Together, these data indicate that PABPC1 is an important cellular target of viral ORF57 to directly upregulate PAN accumulation during viral lytic infection, and the ability of host PABPC1 to disrupt ORF57 expression is a strategic host counterbalancing mechanism.
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Hoshino SI. Mechanism of the initiation of mRNA decay: role of eRF3 family G proteins. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:743-57. [PMID: 22965901 DOI: 10.1002/wrna.1133] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
mRNA decay is intimately linked to and regulated by translation in eukaryotes. However, it has remained unclear exactly how mRNA decay is linked to translation. Progress has been made in recent years in understanding the molecular mechanisms of the link between translation and mRNA decay. It has become clear that the eRF3 family of GTP-binding proteins acts as signal transducers that couple translation to mRNA decay and plays pivotal roles in the regulation of gene expression and mRNA quality control. During translation, the translation termination factor eRF3 in complex with eRF1 recognizes the termination codon which appears at the A site of the terminating ribosome. Depending on whether the termination codon is normal (bona fide) or aberrant (premature), deadenylation-dependent decay or nonsense-mediated mRNA decay (NMD) occurs. mRNA without termination codons and mRNA with the propensity to cause the ribosome to stall are recognized as aberrant by other members of the eRF3 family during translation, and these translational events cause nonstop mRNA decay (NSD) and no-go decay (NGD), respectively. In this review, we focus on how mRNA decay is triggered by translational events and summarize the initiation mechanism for the decay of both normal and aberrant mRNAs.
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Affiliation(s)
- Shin-ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
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The multifunctional poly(A)-binding protein (PABP) 1 is subject to extensive dynamic post-translational modification, which molecular modelling suggests plays an important role in co-ordinating its activities. Biochem J 2012; 441:803-12. [PMID: 22004688 PMCID: PMC3298439 DOI: 10.1042/bj20111474] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
PABP1 [poly(A)-binding protein 1] is a central regulator of mRNA translation and stability and is required for miRNA (microRNA)-mediated regulation and nonsense-mediated decay. Numerous protein, as well as RNA, interactions underlie its multi-functional nature; however, it is unclear how its different activities are co-ordinated, since many partners interact via overlapping binding sites. In the present study, we show that human PABP1 is subject to elaborate post-translational modification, identifying 14 modifications located throughout the functional domains, all but one of which are conserved in mouse. Intriguingly, PABP1 contains glutamate and aspartate methylations, modifications of unknown function in eukaryotes, as well as lysine and arginine methylations, and lysine acetylations. The latter dramatically alter the pI of PABP1, an effect also observed during the cell cycle, suggesting that different biological processes/stimuli can regulate its modification status, although PABP1 also probably exists in differentially modified subpopulations within cells. Two lysine residues were differentially acetylated or methylated, revealing that PABP1 may be the first example of a cytoplasmic protein utilizing a ‘methylation/acetylation switch’. Modelling using available structures implicates these modifications in regulating interactions with individual PAM2 (PABP-interacting motif 2)-containing proteins, suggesting a direct link between PABP1 modification status and the formation of distinct mRNP (messenger ribonucleoprotein) complexes that regulate mRNA fate in the cytoplasm.
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Delage MM, Dutertre S, Le Guével R, Frolova L, Berkova N. Monoclonal antibodies against human translation termination factor eRF3 and their utilization for sub-cellular localization of eRF3. J Biochem 2011; 150:49-59. [PMID: 21421683 DOI: 10.1093/jb/mvr035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Eukaryotic translation termination is triggered by peptide release factors eRF1 and eRF3. eRF1 recognizes the stop codon and promotes nascent peptide chain release, while eRF3 facilitates this peptide release in a GTP-dependent manner. In addition to its role in termination, eRF3 is involved in normal and nonsense-mediated mRNA decay. Despite extensive investigation, the complete understanding of eRF3 function have been hampered by the lack of specific anti-eRF3 monoclonal antibodies (Mabs). The purpose of the study was production of recombinant eRF3a/GSPT1, development of anti-eRF3a/GSPT1 Mabs and their utilization for eRF3a/GSPT1 sub-cellular localization. Plasmid encoding C-terminal part of human GSPT1/eRF3a was constructed. Purified protein, which was predominantly present in the inclusion bodies, was used for the development of Mabs. Characterization of the regions recognized by Mabs using GSPT1/eRF3a mutants and its visualization in the 3D space suggested that Mabs recognize different epitopes. Consistent with its function in translational termination, immunostaining of the cells with developed Mabs revealed that the endogenous GSPT1/eRF3a localized in endoplasmic reticulum. Taking into account the important role of eRF3 for the fundamental research one can suggests that developed Mabs have great prospective to be used as a research reagent in a wide range of applications.
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Yang R, Gaidamakov SA, Xie J, Lee J, Martino L, Kozlov G, Crawford AK, Russo AN, Conte MR, Gehring K, Maraia RJ. La-related protein 4 binds poly(A), interacts with the poly(A)-binding protein MLLE domain via a variant PAM2w motif, and can promote mRNA stability. Mol Cell Biol 2011; 31:542-56. [PMID: 21098120 PMCID: PMC3028612 DOI: 10.1128/mcb.01162-10] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 11/05/2010] [Accepted: 11/12/2010] [Indexed: 12/19/2022] Open
Abstract
The conserved RNA binding protein La recognizes UUU-3'OH on its small nuclear RNA ligands and stabilizes them against 3'-end-mediated decay. We report that newly described La-related protein 4 (LARP4) is a factor that can bind poly(A) RNA and interact with poly(A) binding protein (PABP). Yeast two-hybrid analysis and reciprocal immunoprecipitations (IPs) from HeLa cells revealed that LARP4 interacts with RACK1, a 40S ribosome- and mRNA-associated protein. LARP4 cosediments with 40S ribosome subunits and polyribosomes, and its knockdown decreases translation. Mutagenesis of the RNA binding or PABP interaction motifs decrease LARP4 association with polysomes. Several translation and mRNA metabolism-related proteins use a PAM2 sequence containing a critical invariant phenylalanine to make direct contact with the MLLE domain of PABP, and their competition for the MLLE is thought to regulate mRNA homeostasis. Unlike all ∼150 previously analyzed PAM2 sequences, LARP4 contains a variant PAM2 (PAM2w) with tryptophan in place of the phenylalanine. Binding and nuclear magnetic resonance (NMR) studies have shown that a peptide representing LARP4 PAM2w interacts with the MLLE of PABP within the affinity range measured for other PAM2 motif peptides. A cocrystal of PABC bound to LARP4 PAM2w shows tryptophan in the pocket in PABC-MLLE otherwise occupied by phenylalanine. We present evidence that LARP4 expression stimulates luciferase reporter activity by promoting mRNA stability, as shown by mRNA decay analysis of luciferase and cellular mRNAs. We propose that LARP4 activity is integrated with other PAM2 protein activities by PABP as part of mRNA homeostasis.
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Affiliation(s)
- Ruiqing Yang
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Sergei A. Gaidamakov
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Jingwei Xie
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Joowon Lee
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Luigi Martino
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Guennadi Kozlov
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Amanda K. Crawford
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Amy N. Russo
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Maria R. Conte
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Kalle Gehring
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
| | - Richard J. Maraia
- Intramural Research Program on Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom, Department of Biochemistry, McGill University, Montreal, QC, Canada, Commissioned Corps, U.S. Public Health Service, Washington, DC
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Cytoplasmic poly(A) binding proteins regulate telomerase activity and cell growth in human papillomavirus type 16 E6-expressing keratinocytes. J Virol 2010; 84:12934-44. [PMID: 20943973 DOI: 10.1128/jvi.01377-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The high-risk human papillomavirus (HPV) E6 and E7 oncoproteins are critical to the immortalization of keratinocytes. HPV type 16 (HPV16) E6 interacts with endogenous proteins to activate hTERT, the catalytic subunit of telomerase, thus avoiding cellular senescence signals. NFX1-123, the longer splice variant of NFX1, interacts with HPV16 E6, as well as cytoplasmic poly(A) binding proteins 1 and 4 (PABPC1 and PABPC4). HPV16 E6 affects hTERT expression posttranscriptionally through NFX1-123, as NFX1-123 interacts with hTERT mRNA and stabilizes it, leading to greater telomerase activity. The PAM2 motif of NFX1-123, with which it binds PABPCs, is required for the posttranscriptional regulation of hTERT by HPV16 E6 and NFX1-123. There is increasing evidence that RNA and DNA viruses utilize RNA-processing proteins, and specifically PABPCs, in the normal virus life cycle, and there is also evidence that RNA-processing proteins are perturbed in cancers. Here, we show that PABPCs are critical in hTERT regulation by HPV16 E6. Although the amount and cellular localization of PABPCs were largely unchanged in cervical cancer cell lines with or without HPV16 and in human foreskin keratinocytes (HFKs) with or without HPV16 E6, knockdown of PABPCs decreased hTERT mRNA and telomerase activity and overexpression of PABPC4 increased these in HPV16 E6-expressing HFKs. In contrast, knockdown of PABPCs in C33A cells had no effect on hTERT mRNA or telomerase activity. Additionally, overexpression of PABPC4 and hTERT led to greater growth of cultured HPV16 E6-expressing HFKs. This is the first evidence that PABPCs have a targeted role in hTERT regulation leading to a growth advantage in cells expressing HPV16 E6.
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