1
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Behera A, Panigrahi GK, Sahoo A. Nonsense-Mediated mRNA Decay in Human Health and Diseases: Current Understanding, Regulatory Mechanisms and Future Perspectives. Mol Biotechnol 2024:10.1007/s12033-024-01267-7. [PMID: 39264527 DOI: 10.1007/s12033-024-01267-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 08/24/2024] [Indexed: 09/13/2024]
Abstract
Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that is conserved across all eukaryotes ensuring the quality of transcripts by targeting messenger RNA (mRNA) harbouring premature stop codons. It regulates the gene expression by targeting aberrant mRNA carrying pre-termination codons (PTCs) and eliminates C-terminal truncated proteins. NMD distinguishes aberrant and non-aberrant transcript by looking after long 3' UTRs and exon-junction complex (EJC) downstream of stop codon that indicate the presence of PTC. Therefore, NMD modulates cellular surveillance and eliminates the truncated proteins but if the PTC escapes the surveillance pathway it can lead to potential negative phenotype resulting in genetic diseases. The alternative splicing also contributes in formation of NMD-sensitive isoforms by introducing PTC. NMD plays a complex role in cancer, it can either aggravate or downregulates the tumour. Some tumours agitate NMD to deteriorate mRNAs encoding tumour suppressor proteins, stress response proteins and neoantigens. In other case, tumours suppress the NMD to encourage the expression of oncoproteins for tumour growth and survival. This mechanism augmented in the development of new therapeutics by PTC read-through mechanism and personalized medicine. Detailed studies on NMD surveillance will possibly lead towards development of strategies for improving human health aligning with United Nations sustainable development goals (SDG 3: Good health and well-being). The potential therapeutic applications of NMD pose a challenge in terms of safe and effective modulation. Understanding the complexities of NMD regulation and its interaction with other cellular processes can lead to the development of new interventions for various diseases.
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Affiliation(s)
- Amrita Behera
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India
| | - Gagan Kumar Panigrahi
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India.
| | - Annapurna Sahoo
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India.
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2
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Barbarin-Bocahu I, Ulryck N, Rigobert A, Ruiz Gutierrez N, Decourty L, Raji M, Garkhal B, Le Hir H, Saveanu C, Graille M. Structure of the Nmd4-Upf1 complex supports conservation of the nonsense-mediated mRNA decay pathway between yeast and humans. PLoS Biol 2024; 22:e3002821. [PMID: 39331656 PMCID: PMC11463774 DOI: 10.1371/journal.pbio.3002821] [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: 04/08/2024] [Revised: 10/09/2024] [Accepted: 08/29/2024] [Indexed: 09/29/2024] Open
Abstract
The nonsense-mediated mRNA decay (NMD) pathway clears eukaryotic cells of mRNAs containing premature termination codons (PTCs) or normal stop codons located in specific contexts. It therefore plays an important role in gene expression regulation. The precise molecular mechanism of the NMD pathway has long been considered to differ substantially from yeast to metazoa, despite the involvement of universally conserved factors such as the central ATP-dependent RNA-helicase Upf1. Here, we describe the crystal structure of the yeast Upf1 bound to its recently identified but yet uncharacterized partner Nmd4, show that Nmd4 stimulates Upf1 ATPase activity and that this interaction contributes to the elimination of NMD substrates. We also demonstrate that a region of Nmd4 critical for the interaction with Upf1 in yeast is conserved in the metazoan SMG6 protein, another major NMD factor. We show that this conserved region is involved in the interaction of SMG6 with UPF1 and that mutations in this region affect the levels of endogenous human NMD substrates. Our results support the universal conservation of the NMD mechanism in eukaryotes.
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Affiliation(s)
- Irène Barbarin-Bocahu
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
| | - Nathalie Ulryck
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
| | - Amandine Rigobert
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
| | - Nadia Ruiz Gutierrez
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Laurence Decourty
- Institut Pasteur, Université Paris Cité, Unité Biologie des ARN des Pathogènes Fongiques, Paris, France
| | - Mouna Raji
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
| | - Bhumika Garkhal
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
| | - Hervé Le Hir
- Institut de Biologie de l’Ecole Normale Supérieure (IBENS), Ecole Normale Supérieure, CNRS, INSERM, PSL Research University, Paris, France
| | - Cosmin Saveanu
- Institut Pasteur, Université Paris Cité, Unité Biologie des ARN des Pathogènes Fongiques, Paris, France
| | - Marc Graille
- Laboratoire de Biologie Structurale de la Cellule (BIOC), CNRS, Ecole polytechnique, Institut Polytechnique de Paris, Palaiseau, France
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3
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Langer LM, Kurscheidt K, Basquin J, Bonneau F, Iermak I, Basquin C, Conti E. UPF1 helicase orchestrates mutually exclusive interactions with the SMG6 endonuclease and UPF2. Nucleic Acids Res 2024; 52:6036-6048. [PMID: 38709891 PMCID: PMC11162806 DOI: 10.1093/nar/gkae323] [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: 02/10/2024] [Revised: 04/06/2024] [Accepted: 04/25/2024] [Indexed: 05/08/2024] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a conserved co-translational mRNA surveillance and turnover pathway across eukaryotes. NMD has a central role in degrading defective mRNAs and also regulates the stability of a significant portion of the transcriptome. The pathway is organized around UPF1, an RNA helicase that can interact with several NMD-specific factors. In human cells, degradation of the targeted mRNAs begins with a cleavage event that requires the recruitment of the SMG6 endonuclease to UPF1. Previous studies have identified functional links between SMG6 and UPF1, but the underlying molecular mechanisms have remained elusive. Here, we used mass spectrometry, structural biology and biochemical approaches to identify and characterize a conserved short linear motif in SMG6 that interacts with the cysteine/histidine-rich (CH) domain of UPF1. Unexpectedly, we found that the UPF1-SMG6 interaction is precluded when the UPF1 CH domain is engaged with another NMD factor, UPF2. Based on cryo-EM data, we propose that the formation of distinct SMG6-containing and UPF2-containing NMD complexes may be dictated by different conformational states connected to the RNA-binding status of UPF1. Our findings rationalize a key event in metazoan NMD and advance our understanding of mechanisms regulating activity and guiding substrate recognition by the SMG6 endonuclease.
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Affiliation(s)
- Lukas M Langer
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Katharina Kurscheidt
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Jérôme Basquin
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Fabien Bonneau
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Iuliia Iermak
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Claire Basquin
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
| | - Elena Conti
- Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried/Munich D-82152, Germany
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4
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Temaj G, Chichiarelli S, Telkoparan-Akillilar P, Saha S, Nuhii N, Hadziselimovic R, Saso L. Advances in molecular function of UPF1 in Cancer. Arch Biochem Biophys 2024; 756:109989. [PMID: 38621446 DOI: 10.1016/j.abb.2024.109989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/23/2024] [Accepted: 04/10/2024] [Indexed: 04/17/2024]
Abstract
It is known that more than 10 % of genetic diseases are caused by a mutation in protein-coding mRNA (premature termination codon; PTC). mRNAs with an early stop codon are degraded by the cellular surveillance process known as nonsense-mediated mRNA decay (NMD), which prevents the synthesis of C-terminally truncated proteins. Up-frameshift-1 (UPF1) has been reported to be involved in the downregulation of various cancers, and low expression of UPF1 was shown to correlate with poor prognosis. It is known that UPF1 is a master regulator of nonsense-mediated mRNA decay (NMD). UPF1 may also function as an E3 ligase and degrade target proteins without using mRNA decay mechanisms. Increasing evidence indicates that UPF1 could serve as a good biomarker for cancer diagnosis and treatment for future therapeutic applications. Long non-coding RNAs (lncRNAs) have the ability to bind different proteins and regulate gene expression; this role in cancer cells has already been identified by different studies. This article provides an overview of the aberrant expression of UPF1, its functional properties, and molecular processes during cancer for clinical applications in cancer. We also discussed the interactions of lncRNA with UPF1 for cell growth during tumorigenesis.
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Affiliation(s)
- Gazmend Temaj
- Faculty of Pharmacy, College UBT, 10000, Prishtina, Republic of Kosovo.
| | - Silvia Chichiarelli
- Department of Biochemical Sciences "A. Rossi-Fanelli", Sapienza University of Rome, 00185, Rome, Italy.
| | | | - Sarmistha Saha
- Department of Biotechnology, Institute of Applied Sciences & Humanities, GLA University, Mathura, Uttar Pradesh, India.
| | - Nexhibe Nuhii
- Department of Pharmacy, Faculty of Medical Sciences, State University of Tetovo, 1200, Tetovo, Macedonia.
| | - Rifat Hadziselimovic
- Faculty of Science, University of Sarajevo, 71000, Sarajevo, Bosnia and Herzegovina.
| | - Luciano Saso
- Department of Physiology and Pharmacology "Vittorio Erspamer", La Sapienza University, 00185, Rome, Italy.
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5
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Pacheco M, D’Orazio KN, Lessen LN, Veltri AJ, Neiman Z, Loll-Krippleber R, Brown GW, Green R. Genetic screens in Saccharomyces cerevisiae identify a role for 40S ribosome recycling factors Tma20 and Tma22 in nonsense-mediated decay. G3 (BETHESDA, MD.) 2024; 14:jkad295. [PMID: 38198768 PMCID: PMC10917514 DOI: 10.1093/g3journal/jkad295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 08/29/2023] [Accepted: 12/06/2023] [Indexed: 01/12/2024]
Abstract
The decay of messenger RNA with a premature termination codon by nonsense-mediated decay (NMD) is an important regulatory pathway for eukaryotes and an essential pathway in mammals. NMD is typically triggered by the ribosome terminating at a stop codon that is aberrantly distant from the poly-A tail. Here, we use a fluorescence screen to identify factors involved in NMD in Saccharomyces cerevisiae. In addition to the known NMD factors, including the entire UPF family (UPF1, UPF2, and UPF3), as well as NMD4 and EBS1, we identify factors known to function in posttermination recycling and characterize their contribution to NMD. These observations in S. cerevisiae expand on data in mammals indicating that the 60S recycling factor ABCE1 is important for NMD by showing that perturbations in factors implicated in 40S recycling also correlate with a loss of NMD.
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Affiliation(s)
- Miguel Pacheco
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Karole N D’Orazio
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Laura N Lessen
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Anthony J Veltri
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zachary Neiman
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Raphael Loll-Krippleber
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Grant W Brown
- Department of Biochemistry and Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Rachel Green
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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6
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Das R, Panigrahi GK. Messenger RNA Surveillance: Current Understanding, Regulatory Mechanisms, and Future Implications. Mol Biotechnol 2024:10.1007/s12033-024-01062-4. [PMID: 38411790 DOI: 10.1007/s12033-024-01062-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/02/2024] [Indexed: 02/28/2024]
Abstract
Nonsense-mediated mRNA decay (NMD) is an evolutionarily conserved surveillance mechanism in eukaryotes primarily deployed to ensure RNA quality control by eliminating aberrant transcripts and also involved in modulating the expression of several physiological transcripts. NMD, the mRNA surveillance pathway, is a major form of gene regulation in eukaryotes. NMD serves as one of the most significant quality control mechanisms as it primarily scans the newly synthesized transcripts and differentiates the aberrant and non-aberrant transcripts. The synthesis of truncated proteins is restricted, which would otherwise lead to cellular dysfunctions. The up-frameshift factors (UPFs) play a central role in executing the NMD event, largely by recognizing and recruiting multiple protein factors that result in the decay of non-physiological mRNAs. NMD exhibits astounding variability in its ability across eukaryotes in an array of pathological and physiological contexts. The detailed understanding of NMD and the underlying molecular mechanisms remains blurred. This review outlines our current understanding of NMD, in regulating multifaceted cellular events during development and disease. It also attempts to identify unanswered questions that deserve further investigation.
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Affiliation(s)
- Rutupurna Das
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India
| | - Gagan Kumar Panigrahi
- Department of Zoology, School of Applied Sciences, Centurion University of Technology and Management, Jatni, Khordha, Odisha, India.
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7
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Zavileyskiy LG, Pervouchine DD. Post-transcriptional Regulation of Gene Expression via Unproductive Splicing. Acta Naturae 2024; 16:4-13. [PMID: 38698955 PMCID: PMC11062102 DOI: 10.32607/actanaturae.27337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 03/01/2024] [Indexed: 05/05/2024] Open
Abstract
Unproductive splicing is a mechanism of post-transcriptional gene expression control in which premature stop codons are inserted into protein-coding transcripts as a result of regulated alternative splicing, leading to their degradation via the nonsense-mediated decay pathway. This mechanism is especially characteristic of RNA-binding proteins, which regulate each other's expression levels and those of other genes in multiple auto- and cross-regulatory loops. Deregulation of unproductive splicing is a cause of serious human diseases, including cancers, and is increasingly being considered as a prominent therapeutic target. This review discusses the types of unproductive splicing events, the mechanisms of auto- and cross-regulation, nonsense-mediated decay escape, and problems in identifying unproductive splice isoforms. It also provides examples of deregulation of unproductive splicing in human diseases and discusses therapeutic strategies for its correction using antisense oligonucleotides and small molecules.
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Affiliation(s)
- L. G. Zavileyskiy
- Lomonosov Moscow State University, Moscow, 119192 Russian Federation
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russian Federation
| | - D. D. Pervouchine
- Skolkovo Institute of Science and Technology, Moscow, 121205 Russian Federation
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8
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Carrard J, Lejeune F. Nonsense-mediated mRNA decay, a simplified view of a complex mechanism. BMB Rep 2023; 56:625-632. [PMID: 38052423 PMCID: PMC10761751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/31/2023] [Accepted: 11/17/2023] [Indexed: 12/07/2023] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is both a quality control mechanism and a gene regulation pathway. It has been studied for more than 30 years, with an accumulation of many mechanistic details that have often led to debate and hence to different models of NMD activation, particularly in higher eukaryotes. Two models seem to be opposed, since the first requires intervention of the exon junction complex (EJC) to recruit NMD factors downstream of the premature termination codon (PTC), whereas the second involves an EJC-independent mechanism in which NMD factors concentrate in the 3'UTR to initiate NMD in the presence of a PTC. In this review we describe both models, giving recent molecular details and providing experimental arguments supporting one or the other model. In the end it is certainly possible to imagine that these two mechanisms co-exist, rather than viewing them as mutually exclusive. [BMB Reports 2023; 56(12): 625-632].
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Affiliation(s)
- Julie Carrard
- Univ. Lille, CNRS, Inserm, UMR9020-U1277 - CANTHER - Cancer Heterogeneity Plasticity and Resistance to Therapies, Lille F-59000, France
| | - Fabrice Lejeune
- Univ. Lille, CNRS, Inserm, UMR9020-U1277 - CANTHER - Cancer Heterogeneity Plasticity and Resistance to Therapies, Lille F-59000, France
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9
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Ottens F, Efstathiou S, Hoppe T. Cutting through the stress: RNA decay pathways at the endoplasmic reticulum. Trends Cell Biol 2023:S0962-8924(23)00236-2. [PMID: 38008608 DOI: 10.1016/j.tcb.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/07/2023] [Accepted: 11/08/2023] [Indexed: 11/28/2023]
Abstract
The endoplasmic reticulum (ER) is central to the processing of luminal, transmembrane, and secretory proteins, and maintaining a functional ER is essential for organismal physiology and health. Increased protein-folding load on the ER causes ER stress, which activates quality control mechanisms to restore ER function and protein homeostasis. Beyond protein quality control, mRNA decay pathways have emerged as potent ER fidelity regulators, but their mechanistic roles in ER quality control and their interrelationships remain incompletely understood. Herein, we review ER-associated RNA decay pathways - including regulated inositol-requiring enzyme 1α (IRE1α)-dependent mRNA decay (RIDD), nonsense-mediated mRNA decay (NMD), and Argonaute-dependent RNA silencing - in ER homeostasis, and highlight the intricate coordination of ER-targeted RNA and protein decay mechanisms and their association with antiviral defense.
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Affiliation(s)
- Franziska Ottens
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Sotirios Efstathiou
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Thorsten Hoppe
- Institute for Genetics, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine and University Hospital of Cologne, Cologne, Germany.
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10
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Chapman JH, Youle AM, Grimme AL, Neuman KC, Hogg JR. UPF1 ATPase autoinhibition and activation modulate RNA binding kinetics and NMD efficiency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.03.565554. [PMID: 38076847 PMCID: PMC10705565 DOI: 10.1101/2023.11.03.565554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The RNA helicase UPF1 interacts with mRNAs, mRNA decay machinery, and the terminating ribosome to promote nonsense-mediated mRNA decay (NMD). Structural and biochemical data have revealed that UPF1 exists in an enzymatically autoinhibited "closed" state. Upon binding the NMD protein UPF2, UPF1 undergoes an extensive conformational change into a more enzymatically active "open" state, which exhibits enhanced ATPase and helicase activity. However, mechanically deficient UPF1 mutants can support efficient NMD, bringing into question the roles of UPF1 enzymatic autoinhibition and activation in NMD. Here, we identify two additional important features of the activated open state: slower nucleic acid binding kinetics and enhanced ATP-stimulated nucleic acid dissociation kinetics. Computational modeling based on empirical measurements of UPF1, UPF2, and RNA interaction kinetics predicts that the majority of UPF1-RNA binding and dissociation events in cells occur independently of UPF2 binding. We find that UPF1 mutants with either reduced or accelerated dissociation from RNA have NMD defects, whereas UPF1 mutants that are more dependent on UPF2 for catalytic activity remain active on well-established NMD targets. These findings support a model in which the kinetics of UPF1-mRNA interactions are important determinants of cellular NMD efficiency.
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Affiliation(s)
- Joseph H. Chapman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Alice M. Youle
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Acadia L. Grimme
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - Keir C. Neuman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
| | - J. Robert Hogg
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, 20892, USA
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11
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Larivera S, Neumeier J, Meister G. Post-transcriptional gene silencing in a dynamic RNP world. Biol Chem 2023; 404:1051-1067. [PMID: 37739934 DOI: 10.1515/hsz-2023-0203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/04/2023] [Indexed: 09/24/2023]
Abstract
MicroRNA (miRNA)-guided gene silencing is a key regulatory process in various organisms and linked to many human diseases. MiRNAs are processed from precursor molecules and associate with Argonaute proteins to repress the expression of complementary target mRNAs. Excellent work by numerous labs has contributed to a detailed understanding of the mechanisms of miRNA function. However, miRNA effects have mostly been analyzed and viewed as isolated events and their natural environment as part of complex RNA-protein particles (RNPs) is often neglected. RNA binding proteins (RBPs) regulate key enzymes of the miRNA processing machinery and furthermore RBPs or readers of RNA modifications may modulate miRNA activity on mRNAs. Such proteins may function similarly to miRNAs and add their own contributions to the overall expression level of a particular gene. Therefore, post-transcriptional gene regulation might be more the sum of individual regulatory events and should be viewed as part of a dynamic and complex RNP world.
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Affiliation(s)
- Simone Larivera
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, D-93053, Regensburg, Germany
| | - Julia Neumeier
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, D-93053, Regensburg, Germany
| | - Gunter Meister
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, D-93053, Regensburg, Germany
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12
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Monaghan L, Longman D, Cáceres JF. Translation-coupled mRNA quality control mechanisms. EMBO J 2023; 42:e114378. [PMID: 37605642 PMCID: PMC10548175 DOI: 10.15252/embj.2023114378] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/24/2023] [Accepted: 08/01/2023] [Indexed: 08/23/2023] Open
Abstract
mRNA surveillance pathways are essential for accurate gene expression and to maintain translation homeostasis, ensuring the production of fully functional proteins. Future insights into mRNA quality control pathways will enable us to understand how cellular mRNA levels are controlled, how defective or unwanted mRNAs can be eliminated, and how dysregulation of these can contribute to human disease. Here we review translation-coupled mRNA quality control mechanisms, including the non-stop and no-go mRNA decay pathways, describing their mechanisms, shared trans-acting factors, and differences. We also describe advances in our understanding of the nonsense-mediated mRNA decay (NMD) pathway, highlighting recent mechanistic findings, the discovery of novel factors, as well as the role of NMD in cellular physiology and its impact on human disease.
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Affiliation(s)
- Laura Monaghan
- MRC Human Genetics Unit, Institute of Genetics and CancerUniversity of EdinburghEdinburghUK
| | - Dasa Longman
- MRC Human Genetics Unit, Institute of Genetics and CancerUniversity of EdinburghEdinburghUK
| | - Javier F Cáceres
- MRC Human Genetics Unit, Institute of Genetics and CancerUniversity of EdinburghEdinburghUK
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13
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Shen S, Zhang C, Meng Y, Cui G, Wang Y, Liu X, He Q. Sensing of H2O2-induced oxidative stress by the UPF factor complex is crucial for activation of catalase-3 expression in Neurospora. PLoS Genet 2023; 19:e1010985. [PMID: 37844074 PMCID: PMC10578600 DOI: 10.1371/journal.pgen.1010985] [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: 06/20/2023] [Accepted: 09/19/2023] [Indexed: 10/18/2023] Open
Abstract
UPF-1-UPF-2-UPF-3 complex-orchestrated nonsense-mediated mRNA decay (NMD) is a well-characterized eukaryotic cellular surveillance mechanism that not only degrades aberrant transcripts to protect the integrity of the transcriptome but also eliminates normal transcripts to facilitate appropriate cellular responses to physiological and environmental changes. Here, we describe the multifaceted regulatory roles of the Neurospora crassa UPF complex in catalase-3 (cat-3) gene expression, which is essential for scavenging H2O2-induced oxidative stress. First, losing UPF proteins markedly slowed down the decay rate of cat-3 mRNA. Second, UPF proteins indirectly attenuated the transcriptional activity of cat-3 gene by boosting the decay of cpc-1 and ngf-1 mRNAs, which encode a well-studied transcription factor and a histone acetyltransferase, respectively. Further study showed that under oxidative stress condition, UPF proteins were degraded, followed by increased CPC-1 and NGF-1 activity, finally activating cat-3 expression to resist oxidative stress. Together, our data illustrate a sophisticated regulatory network of the cat-3 gene mediated by the UPF complex under physiological and H2O2-induced oxidative stress conditions.
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Affiliation(s)
- Shuangjie Shen
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Chengcheng Zhang
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Yuanhao Meng
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Guofei Cui
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Ying Wang
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiao Liu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - Qun He
- MOA Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing, China
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14
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Petrić Howe M, Patani R. Nonsense-mediated mRNA decay in neuronal physiology and neurodegeneration. Trends Neurosci 2023; 46:879-892. [PMID: 37543480 DOI: 10.1016/j.tins.2023.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/19/2023] [Accepted: 07/09/2023] [Indexed: 08/07/2023]
Abstract
The processes of mRNA export from the nucleus and subsequent mRNA translation in the cytoplasm are of particular relevance in eukaryotic cells. In highly polarised cells such as neurons, finely-tuned molecular regulation of these processes serves to safeguard the spatiotemporal fidelity of gene expression. Nonsense-mediated mRNA decay (NMD) is a cytoplasmic translation-dependent quality control process that regulates gene expression in a wide range of scenarios in the nervous system, including neurodevelopment, learning, and memory formation. Moreover, NMD dysregulation has been implicated in a broad range of neurodevelopmental and neurodegenerative disorders. We discuss how NMD and related aspects of mRNA translation regulate key neuronal functions and, in particular, we focus on evidence implicating these processes in the molecular pathogenesis of neurodegeneration. Finally, we discuss the therapeutic potential and challenges of targeting mRNA translation and NMD across the spectrum of largely untreatable neurological diseases.
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Affiliation(s)
- Marija Petrić Howe
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London (UCL), Queen Square, WC1N 3BG London, UK.
| | - Rickie Patani
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK; Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London (UCL), Queen Square, WC1N 3BG London, UK.
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15
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Viscardi MJ, Arribere JA. NMD targets experience deadenylation during their maturation and endonucleolytic cleavage during their decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560204. [PMID: 37808772 PMCID: PMC10557752 DOI: 10.1101/2023.09.29.560204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Premature stop codon-containing mRNAs can produce truncated and dominantly acting proteins that harm cells. Eukaryotic cells protect themselves by degrading such mRNAs via the Nonsense-Mediated mRNA Decay (NMD) pathway. The precise reactions by which cells attack NMD target mRNAs remain obscure, precluding a mechanistic understanding of NMD and hampering therapeutic efforts to control NMD. A key step in NMD is the decay of the mRNA, which is proposed to occur via several competing models including deadenylation, exonucleolytic decay, and/or endonucleolytic decay. We set out to clarify the relative contributions of these decay mechanisms to NMD, and to identify the role of key factors. Here, we modify and deploy single-molecule nanopore mRNA sequencing to capture full-length NMD targets and their degradation intermediates, and we obtain single-molecule measures of splicing isoform, cleavage state, and poly(A) tail length. We observe robust endonucleolytic cleavage of NMD targets in vivo that depends on the nuclease SMG-6 and we use the occurence of cleavages to identify several known NMD targets. We show that NMD target mRNAs experience deadenylation, but similar to the extent that normal mRNAs experience as they enter the translational pool. Furthermore, we show that a factor (SMG-5) that historically was ascribed a function in deadenylation, is in fact required for SMG-6-mediated cleavage. Our results support a model in which NMD factors act in concert to degrade NMD targets in animals via an endonucleolytic cleavage near the stop codon, and suggest that deadenylation is a normal part of mRNA (and NMD target) maturation rather than a facet unique to NMD. Our work clarifies the route by which NMD target mRNAs are attacked in an animal.
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Affiliation(s)
- Marcus J. Viscardi
- Department of Molecular, Cellular and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Joshua A. Arribere
- Department of Molecular, Cellular and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
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16
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Nasif S, Colombo M, Uldry AC, Schröder M, de Brot S, Mühlemann O. Inhibition of nonsense-mediated mRNA decay reduces the tumorigenicity of human fibrosarcoma cells. NAR Cancer 2023; 5:zcad048. [PMID: 37681034 PMCID: PMC10480688 DOI: 10.1093/narcan/zcad048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/08/2023] [Accepted: 08/25/2023] [Indexed: 09/09/2023] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a eukaryotic RNA decay pathway with roles in cellular stress responses, differentiation, and viral defense. It functions in both quality control and post-transcriptional regulation of gene expression. NMD has also emerged as a modulator of cancer progression, although available evidence supports both a tumor suppressor and a pro-tumorigenic role, depending on the model. To further investigate the role of NMD in cancer, we knocked out the NMD factor SMG7 in the HT1080 human fibrosarcoma cell line, resulting in suppression of NMD function. We then compared the oncogenic properties of the parental cell line, the SMG7-knockout, and a rescue cell line in which we re-introduced both isoforms of SMG7. We also tested the effect of a drug inhibiting the NMD factor SMG1 to distinguish NMD-dependent effects from putative NMD-independent functions of SMG7. Using cell-based assays and a mouse xenograft tumor model, we showed that suppression of NMD function severely compromises the oncogenic phenotype. Molecular pathway analysis revealed that NMD suppression strongly reduces matrix metalloprotease 9 (MMP9) expression and that MMP9 re-expression partially rescues the oncogenic phenotype. Since MMP9 promotes cancer cell migration and invasion, metastasis and angiogenesis, its downregulation may contribute to the reduced tumorigenicity of NMD-suppressed cells. Collectively, our results highlight the potential value of NMD inhibition as a therapeutic approach.
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Affiliation(s)
- Sofia Nasif
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Switzerland
| | - Martino Colombo
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Switzerland
| | - Anne-Christine Uldry
- Proteomics & Mass Spectrometry Core Facility, Department for BioMedical Research, University of Bern, Switzerland
| | - Markus S Schröder
- NCCR RNA & Disease Bioinformatics Support,Department of Biology, ETH Zürich, Switzerland
| | - Simone de Brot
- COMPATH, Institute of Animal Pathology, University of Bern, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Switzerland
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17
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Steiner AJ, Zheng Y, Tang Y. Characterization of a rhabdomyosarcoma reveals a critical role for SMG7 in cancer cell viability and tumor growth. Sci Rep 2023; 13:10152. [PMID: 37349371 PMCID: PMC10287741 DOI: 10.1038/s41598-023-36568-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 06/06/2023] [Indexed: 06/24/2023] Open
Abstract
Soft-tissue sarcomas (STSs) are a rare and diverse group of mesenchymal cancers plagued with aggression, poor response to systemic therapy, and high rates of recurrence. Although STSs generally have low mutational burdens, the most commonly mutated genes are tumor suppressors, which frequently acquire mutations inducing nonsense-mediated mRNA decay (NMD). This suggests that STS cells may exploit NMD to suppress these anti-cancer genes. To examine the role that the NMD factor SMG7 plays in STS, we developed an inducible knockout mouse model in the Trp53-/- background. Here, we isolated a subcutaneous STS and identified it as a rhabdomyosarcoma (RMS). We report that knockout of SMG7 significantly inhibited NMD in our RMS cells, which led to the induction of NMD targets GADD45b and the tumor suppressor GAS5. The loss of NMD and upregulation of these anti-cancer genes were concomitant with the loss of RMS cell viability and inhibited tumor growth. Importantly, SMG7 was dispensable for homeostasis in our mouse embryonic fibroblasts and adult mice. Overall, our data show that the loss of SMG7 induces a strong anti-cancer effect both in vitro and in vivo. We present here the first evidence that disrupting SMG7 function may be tolerable and provide a therapeutic benefit for STS treatment.
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Affiliation(s)
- Alexander J Steiner
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Yang Zheng
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA
| | - Yi Tang
- Department of Regenerative and Cancer Cell Biology, Albany Medical College, 47 New Scotland Avenue, Albany, NY, 12208, USA.
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18
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Hsieh MC, Lai CY, Yeh CM, Yang PS, Cheng JK, Wang HH, Lin KH, Nie ST, Lin TB, Peng HY. Phosphorylated Upstream Frameshift 1-dependent Nonsense-mediated μ-Opioid Receptor mRNA Decay in the Spinal Cord Contributes to the Development of Neuropathic Allodynia-like Behavior in Rats. Anesthesiology 2023; 138:634-655. [PMID: 36867667 DOI: 10.1097/aln.0000000000004550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
BACKGROUND Nonsense-mediated messenger RNA (mRNA) decay increases targeted mRNA degradation and has been implicated in the regulation of gene expression in neurons. The authors hypothesized that nonsense-mediated μ-opioid receptor mRNA decay in the spinal cord is involved in the development of neuropathic allodynia-like behavior in rats. METHODS Adult Sprague-Dawley rats of both sexes received spinal nerve ligation to induce neuropathic allodynia-like behavior. The mRNA and protein expression contents in the dorsal horn of animals were measured by biochemical analyses. Nociceptive behaviors were evaluated by the von Frey test and the burrow test. RESULTS On Day 7, spinal nerve ligation significantly increased phosphorylated upstream frameshift 1 (UPF1) expression in the dorsal horn (mean ± SD; 0.34 ± 0.19 in the sham ipsilateral group vs. 0.88 ± 0.15 in the nerve ligation ipsilateral group; P < 0.001; data in arbitrary units) and drove allodynia-like behaviors in rats (10.58 ± 1.72 g in the sham ipsilateral group vs. 1.19 ± 0.31 g in the nerve ligation ipsilateral group, P < 0.001). No sex-based differences were found in either Western blotting or behavior tests in rats. Eukaryotic translation initiation factor 4A3 (eIF4A3) triggered SMG1 kinase (0.06 ± 0.02 in the sham group vs. 0.20 ± 0.08 in the nerve ligation group, P = 0.005, data in arbitrary units)-mediated UPF1 phosphorylation, leading to increased nonsense-mediated mRNA decay factor SMG7 binding and µ-opioid receptor mRNA degradation (0.87 ± 0.11-fold in the sham group vs. 0.50 ± 0.11-fold in the nerve ligation group, P = 0.002) in the dorsal horn of the spinal cord after spinal nerve ligation. Pharmacologic or genetic inhibition of this signaling pathway in vivo ameliorated allodynia-like behaviors after spinal nerve ligation. CONCLUSIONS This study suggests that phosphorylated UPF1-dependent nonsense-mediated μ-opioid receptor mRNA decay is involved in the pathogenesis of neuropathic pain. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Ming-Chun Hsieh
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
| | - Cheng-Yuan Lai
- Institute of Biomedical Sciences, MacKay Medical College, New Taipei City, Taiwan
| | - Chou-Ming Yeh
- Division of Thoracic Surgery, Department of Health, Taichung Hospital, Executive Yuan, Taichung, Taiwan; Central Taiwan University of Science and Technology, Taichung, Taiwan
| | - Po-Sheng Yang
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan; Department of Surgery, Mackay Memorial Hospital, Taipei, Taiwan
| | - Jen-Kun Cheng
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan; Department of Anesthesiology, Mackay Memorial Hospital, Taipei, Taiwan
| | - Hsueh-Hsiao Wang
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
| | - Kuan-Hung Lin
- Institute of Biomedical Sciences, MacKay Medical College, New Taipei City, Taiwan; Traditional Herbal Medicine Research Center, Taipei Medical University Hospital, Taipei, Taiwan; Department of Pharmacology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Siao-Tong Nie
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan
| | - Tzer-Bin Lin
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei City, Taiwan; Institute of New Drug Development, College of Medicine, China Medical University, Taichung, Taiwan
| | - Hsien-Yu Peng
- Department of Medicine, Mackay Medical College, New Taipei, Taiwan; Institute of Biomedical Sciences, MacKay Medical College, New Taipei City, Taiwan
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19
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Ahmed MR, Du Z. Molecular Interaction of Nonsense-Mediated mRNA Decay with Viruses. Viruses 2023; 15:v15040816. [PMID: 37112798 PMCID: PMC10141005 DOI: 10.3390/v15040816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/14/2023] [Accepted: 02/28/2023] [Indexed: 03/30/2023] Open
Abstract
The virus–host interaction is dynamic and evolutionary. Viruses have to fight with hosts to establish successful infection. Eukaryotic hosts are equipped with multiple defenses against incoming viruses. One of the host antiviral defenses is the nonsense-mediated mRNA decay (NMD), an evolutionarily conserved mechanism for RNA quality control in eukaryotic cells. NMD ensures the accuracy of mRNA translation by removing the abnormal mRNAs harboring pre-matured stop codons. Many RNA viruses have a genome that contains internal stop codon(s) (iTC). Akin to the premature termination codon in aberrant RNA transcripts, the presence of iTC would activate NMD to degrade iTC-containing viral genomes. A couple of viruses have been reported to be sensitive to the NMD-mediated antiviral defense, while some viruses have evolved with specific cis-acting RNA features or trans-acting viral proteins to overcome or escape from NMD. Recently, increasing light has been shed on the NMD–virus interaction. This review summarizes the current scenario of NMD-mediated viral RNA degradation and classifies various molecular means by which viruses compromise the NMD-mediated antiviral defense for better infection in their hosts.
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Affiliation(s)
| | - Zhiyou Du
- Correspondence: ; Tel.: +86-571-86843195
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20
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The biological functions of nonsense-mediated mRNA decay in plants: RNA quality control and beyond. Biochem Soc Trans 2023; 51:31-39. [PMID: 36695509 DOI: 10.1042/bst20211231] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/11/2023] [Accepted: 01/13/2023] [Indexed: 01/26/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is an evolutionarily conserved quality control pathway that inhibits the expression of transcripts containing premature termination codon. Transcriptome and phenotypic studies across a range of organisms indicate roles of NMD beyond RNA quality control and imply its involvement in regulating gene expression in a wide range of physiological processes. Studies in moss Physcomitrella patens and Arabidopsis thaliana have shown that NMD is also important in plants where it contributes to the regulation of pathogen defence, hormonal signalling, circadian clock, reproduction and gene evolution. Here, we provide up to date overview of the biological functions of NMD in plants. In addition, we discuss several biological processes where NMD factors implement their function through NMD-independent mechanisms.
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21
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Xue G, Maciej VD, Machado de Amorim A, Pak M, Jayachandran U, Chakrabarti S. Modulation of RNA-binding properties of the RNA helicase UPF1 by its activator UPF2. RNA (NEW YORK, N.Y.) 2023; 29:178-187. [PMID: 36456182 PMCID: PMC9891255 DOI: 10.1261/rna.079188.122] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 11/06/2022] [Indexed: 06/17/2023]
Abstract
The NMD helicase UPF1 is a prototype of the superfamily 1 (SF1) of RNA helicases that bind RNA with high affinity and translocate on it in an ATP-dependent manner. Previous studies showed that UPF1 has a low basal catalytic activity that is greatly enhanced upon binding of its interaction partner, UPF2. Activation of UPF1 by UPF2 entails a large conformational change that switches the helicase from an RNA-clamping mode to an RNA-unwinding mode. The ability of UPF1 to bind RNA was expected to be unaffected by this activation mechanism. Here we show, using a combination of biochemical and biophysical methods, that binding of UPF2 to UPF1 drastically reduces the affinity of UPF1 for RNA, leading to a release of the bound RNA. Although UPF2 is capable of binding RNA in vitro, our results suggest that dissociation of the UPF1-RNA complex is not a consequence of direct competition in RNA binding but rather an allosteric effect that is likely mediated by the conformational change in UPF1 that is induced upon binding its activator. We discuss these results in light of transient interactions forged during mRNP assembly, particularly in the UPF1-dependent mRNA decay pathways.
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Affiliation(s)
- Guangpu Xue
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Vincent D Maciej
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | | | - Melis Pak
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Uma Jayachandran
- Max Planck Institute of Biochemistry, Structural Cell Biology Department, D-82152 Martinsried, Germany
| | - Sutapa Chakrabarti
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany
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22
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Leon KE, Khalid MM, Flynn RA, Fontaine KA, Nguyen TT, Kumar GR, Simoneau CR, Tomar S, Jimenez-Morales D, Dunlap M, Kaye J, Shah PS, Finkbeiner S, Krogan NJ, Bertozzi C, Carette JE, Ott M. Nuclear accumulation of host transcripts during Zika Virus Infection. PLoS Pathog 2023; 19:e1011070. [PMID: 36603024 PMCID: PMC9847913 DOI: 10.1371/journal.ppat.1011070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 01/18/2023] [Accepted: 12/17/2022] [Indexed: 01/06/2023] Open
Abstract
Zika virus (ZIKV) infects fetal neural progenitor cells (NPCs) causing severe neurodevelopmental disorders in utero. Multiple pathways involved in normal brain development are dysfunctional in infected NPCs but how ZIKV centrally reprograms these pathways remains unknown. Here we show that ZIKV infection disrupts subcellular partitioning of host transcripts critical for neurodevelopment in NPCs and functionally link this process to the up-frameshift protein 1 (UPF1). UPF1 is an RNA-binding protein known to regulate decay of cellular and viral RNAs and is less expressed in ZIKV-infected cells. Using infrared crosslinking immunoprecipitation and RNA sequencing (irCLIP-Seq), we show that a subset of mRNAs loses UPF1 binding in ZIKV-infected NPCs, consistent with UPF1's diminished expression. UPF1 target transcripts, however, are not altered in abundance but in subcellular localization, with mRNAs accumulating in the nucleus of infected or UPF1 knockdown cells. This leads to diminished protein expression of FREM2, a protein required for maintenance of NPC identity. Our results newly link UPF1 to the regulation of mRNA transport in NPCs, a process perturbed during ZIKV infection.
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Affiliation(s)
- Kristoffer E. Leon
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Medicine, University of California, San Francisco, California, United States of America
- Medical Scientist Training Program, University of California, San Francisco, California, United States of America
- Biomedical Sciences Graduate Program, University of California, San Francisco, California, United States of America
| | - Mir M. Khalid
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Ryan A. Flynn
- Stem Cell Program, Boston Children’s Hospital, Boston, Massachusetts, United States of America
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Krystal A. Fontaine
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Thong T. Nguyen
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - G. Renuka Kumar
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Camille R. Simoneau
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Medicine, University of California, San Francisco, California, United States of America
- Biomedical Sciences Graduate Program, University of California, San Francisco, California, United States of America
| | - Sakshi Tomar
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - David Jimenez-Morales
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, California, United States of America
| | - Mariah Dunlap
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Julia Kaye
- J. David Gladstone Institutes, San Francisco, California, United States of America
| | - Priya S. Shah
- Departments of Chemical Engineering and Microbiology and Molecular Genetics, University of California, Davis, California, United States of America
| | - Steven Finkbeiner
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Center for Systems and Therapeutics and Taube/Koret Center for Neurodegenerative Disease Research, San Francisco, California, United States of America
- Departments of Neurology and Physiology, University of California, San Francisco, California, United States of America
| | - Nevan J. Krogan
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, California, United States of America
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California, United States of America
| | - Carolyn Bertozzi
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jan E. Carette
- Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America
| | - Melanie Ott
- J. David Gladstone Institutes, San Francisco, California, United States of America
- Department of Medicine, University of California, San Francisco, California, United States of America
- Chan Zuckerberg Biohub, San Francisco, California, United States of America
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23
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Ganesan R, Mangkalaphiban K, Baker RE, He F, Jacobson A. Ribosome-bound Upf1 forms distinct 80S complexes and conducts mRNA surveillance. RNA (NEW YORK, N.Y.) 2022; 28:1621-1642. [PMID: 36192133 PMCID: PMC9670811 DOI: 10.1261/rna.079416.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Upf1, Upf2, and Upf3, the central regulators of nonsense-mediated mRNA decay (NMD), appear to exercise their NMD functions while bound to elongating ribosomes, and evidence for this conclusion is particularly compelling for Upf1. Hence, we used selective profiling of yeast Upf1:ribosome association to define that step in greater detail, understand whether the nature of the mRNA being translated influences Upf1:80S interaction, and elucidate the functions of ribosome-associated Upf1. Our approach has allowed us to clarify the timing and specificity of Upf1 association with translating ribosomes, obtain evidence for a Upf1 mRNA surveillance function that precedes the activation of NMD, identify a unique ribosome state that generates 37-43 nt ribosome footprints whose accumulation is dependent on Upf1's ATPase activity, and demonstrate that a mutated form of Upf1 can interfere with normal translation termination and ribosome release. In addition, our results strongly support the existence of at least two distinct functional Upf1 complexes in the NMD pathway.
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Affiliation(s)
- Robin Ganesan
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Kotchaphorn Mangkalaphiban
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Richard E Baker
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Feng He
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts 01655, USA
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24
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Raisch T, Valkov E. Regulation of the multisubunit CCR4-NOT deadenylase in the initiation of mRNA degradation. Curr Opin Struct Biol 2022; 77:102460. [PMID: 36116370 PMCID: PMC9771892 DOI: 10.1016/j.sbi.2022.102460] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/19/2022] [Accepted: 08/10/2022] [Indexed: 12/24/2022]
Abstract
The conserved CCR4-NOT complex initiates the decay of mRNAs by catalyzing the shortening of their poly(A) tails in a process known as deadenylation. Recent studies have provided mechanistic insights into the action and regulation of this molecular machine. The two catalytic enzymatic subunits of the complex hydrolyze polyadenosine RNA. Notably, the non-catalytic subunits substantially enhance the complex's affinity and sequence selectivity for polyadenosine by directly contacting the RNA. An additional regulatory mechanism is the active recruitment of the CCR4-NOT to transcripts targeted for decay by RNA-binding proteins that recognize motifs or sequences residing predominantly in untranslated regions. This targeting and strict control of the mRNA deadenylation process emerges as a crucial nexus during post-transcriptional regulation of gene expression.
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Affiliation(s)
- Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
| | - Eugene Valkov
- RNA Biology Laboratory & Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
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25
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Chapman JH, Craig JM, Wang CD, Gundlach JH, Neuman K, Hogg J. UPF1 mutants with intact ATPase but deficient helicase activities promote efficient nonsense-mediated mRNA decay. Nucleic Acids Res 2022; 50:11876-11894. [PMID: 36370101 PMCID: PMC9723629 DOI: 10.1093/nar/gkac1026] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/12/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
Abstract
The conserved RNA helicase UPF1 coordinates nonsense-mediated mRNA decay (NMD) by engaging with mRNAs, RNA decay machinery and the terminating ribosome. UPF1 ATPase activity is implicated in mRNA target discrimination and completion of decay, but the mechanisms through which UPF1 enzymatic activities such as helicase, translocase, RNP remodeling, and ATPase-stimulated dissociation influence NMD remain poorly defined. Using high-throughput biochemical assays to quantify UPF1 enzymatic activities, we show that UPF1 is only moderately processive (<200 nt) in physiological contexts and undergoes ATPase-stimulated dissociation from RNA. We combine an in silico screen with these assays to identify and characterize known and novel UPF1 mutants with altered helicase, ATPase, and RNA binding properties. We find that UPF1 mutants with substantially impaired processivity (E797R, G619K/A546H), faster (G619K) or slower (K547P, E797R, G619K/A546H) unwinding rates, and/or reduced mechanochemical coupling (i.e. the ability to harness ATP hydrolysis for work; K547P, R549S, G619K, G619K/A546H) can still support efficient NMD of well-characterized targets in human cells. These data are consistent with a central role for UPF1 ATPase activity in driving cycles of RNA binding and dissociation to ensure accurate NMD target selection.
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Affiliation(s)
- Joseph H Chapman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jonathan M Craig
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Clara D Wang
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jens H Gundlach
- Department of Physics, University of Washington, Seattle, WA, USA
| | - Keir C Neuman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - J Robert Hogg
- To whom correspondence should be addressed. Tel: +1 301 827 0724; Fax: +1 301 451 5459;
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26
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Kim JH, Modena MS, Sehgal E, Courney A, Neudorf C, Arribere J. SMG-6 mRNA cleavage stalls ribosomes near premature stop codons in vivo. Nucleic Acids Res 2022; 50:8852-8866. [PMID: 35950494 PMCID: PMC9410879 DOI: 10.1093/nar/gkac681] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/29/2022] [Accepted: 07/26/2022] [Indexed: 12/24/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) protects cells from the toxic and potentially dominant effects of truncated proteins. Targeting of mRNAs with early stop codons is mediated by the ribosome and spatiotemporally aligned with translation termination. Previously we identified a novel NMD intermediate: ribosomes stalled on cleaved stop codons, raising the possibility that NMD begins even prior to ribosome removal from the stop codon. Here we show that this intermediate is the result of mRNA cleavage by the endonuclease SMG-6. Our work supports a model in which ribosomes stall secondary to SMG-6 mRNA cleavage in Caenorhabditis elegans and humans, i.e. that the novel NMD intermediate occurs after a prior ribosome elicits NMD. Our genetic analysis of C. elegans' SMG-6 supports a central role for SMG-6 in metazoan NMD, and provides a context for evaluating its function in other metazoans.
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Affiliation(s)
- John H Kim
- Department of MCD Biology, UC Santa Cruz, California, USA
| | | | - Enisha Sehgal
- Department of MCD Biology, UC Santa Cruz, California, USA
| | - Annie Courney
- Department of MCD Biology, UC Santa Cruz, California, USA
| | - Celine W Neudorf
- Department of Biomolecular Engineering, UC Santa Cruz, California, USA
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27
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Cho H, Abshire ET, Popp MW, Pröschel C, Schwartz JL, Yeo GW, Maquat LE. AKT constitutes a signal-promoted alternative exon-junction complex that regulates nonsense-mediated mRNA decay. Mol Cell 2022; 82:2779-2796.e10. [PMID: 35675814 PMCID: PMC9357146 DOI: 10.1016/j.molcel.2022.05.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 04/21/2022] [Accepted: 05/10/2022] [Indexed: 11/28/2022]
Abstract
Despite a long appreciation for the role of nonsense-mediated mRNA decay (NMD) in destroying faulty, disease-causing mRNAs and maintaining normal, physiologic mRNA abundance, additional effectors that regulate NMD activity in mammalian cells continue to be identified. Here, we describe a haploid-cell genetic screen for NMD effectors that has unexpectedly identified 13 proteins constituting the AKT signaling pathway. We show that AKT supersedes UPF2 in exon-junction complexes (EJCs) that are devoid of RNPS1 but contain CASC3, defining an unanticipated insulin-stimulated EJC. Without altering UPF1 RNA binding or ATPase activity, AKT-mediated phosphorylation of the UPF1 CH domain at T151 augments UPF1 helicase activity, which is critical for NMD and also decreases the dependence of helicase activity on ATP. We demonstrate that upregulation of AKT signaling contributes to the hyperactivation of NMD that typifies Fragile X syndrome, as exemplified using FMR1-KO neural stem cells derived from induced pluripotent stem cells.
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Affiliation(s)
- Hana Cho
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA
| | - Elizabeth T Abshire
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA
| | - Maximilian W Popp
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA
| | - Christoph Pröschel
- Department of Biomedical Genetics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Stem Cell and Regenerative Medicine Institute, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA
| | - Joshua L Schwartz
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA, USA; Stem Cell Program, University of California, San Diego, La Jolla, CA, USA; Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY 14642, USA; Center for RNA Biology, University of Rochester, Rochester, NY 14642, USA.
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28
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Karousis ED, Mühlemann O. The broader sense of nonsense. Trends Biochem Sci 2022; 47:921-935. [PMID: 35780009 DOI: 10.1016/j.tibs.2022.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/30/2022] [Accepted: 06/08/2022] [Indexed: 12/21/2022]
Abstract
The term 'nonsense-mediated mRNA decay' (NMD) was initially coined to describe the translation-dependent degradation of mRNAs harboring premature termination codons (PTCs), but it is meanwhile known that NMD also targets many canonical mRNAs with numerous biological implications. The molecular mechanisms determining on which RNAs NMD ensues are only partially understood. Considering the broad range of NMD-sensitive RNAs and the variable degrees of their degradation, we highlight here the hallmarks of mammalian NMD and point out open questions. We review the links between NMD and disease by summarizing the role of NMD in cancer, neurodegeneration, and viral infections. Finally, we describe strategies to modulate NMD activity and specificity as potential therapeutic approaches for various diseases.
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Affiliation(s)
- Evangelos D Karousis
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.
| | - Oliver Mühlemann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.
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29
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Boo SH, Ha H, Lee Y, Shin MK, Lee S, Kim YK. UPF1 promotes rapid degradation of m 6A-containing RNAs. Cell Rep 2022; 39:110861. [PMID: 35613594 DOI: 10.1016/j.celrep.2022.110861] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 03/11/2022] [Accepted: 05/02/2022] [Indexed: 11/03/2022] Open
Abstract
N6-methyladenosine (m6A) is the most prevalent internal modification in eukaryotic mRNAs and affects RNA processing and metabolism. When YTHDF2, an m6A-recognizing protein, binds to m6A, it facilitates the destabilization of m6A-containing RNAs (m6A RNAs). Here, we demonstrate that upstream frameshift 1 (UPF1), a key factor for nonsense-mediated mRNA decay, interacts with YTHDF2, thereby triggering rapid degradation of m6A RNAs. The UPF1-mediated m6A RNA degradation depends on a specific interaction between UPF1 and N-terminal residues 101-168 of YTHDF2, UPF1 ATPase/helicase activities, and UPF1 interaction with proline-rich nuclear receptor coactivator 2 (PNRC2), a decapping-promoting factor preferentially involved in nonsense-mediated mRNA decay. Furthermore, transcriptome-wide analyses show that YTHDF2-bound mRNAs that are not substrates for HRSP12-RNase P/MRP-mediated endoribonucleolytic cleavage are destabilized with a higher dependency on UPF1. Collectively, our data indicate dynamic and multilayered regulation of the stability of m6A RNAs and highlight the multifaceted role of UPF1 in mRNA decay.
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Affiliation(s)
- Sung Ho Boo
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Hongseok Ha
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Yujin Lee
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Min-Kyung Shin
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Sena Lee
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Yoon Ki Kim
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea; Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea.
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30
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Fritz SE, Ranganathan S, Wang CD, Hogg JR. An alternative UPF1 isoform drives conditional remodeling of nonsense-mediated mRNA decay. EMBO J 2022; 41:e108898. [PMID: 35403729 PMCID: PMC9108617 DOI: 10.15252/embj.2021108898] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 03/18/2022] [Accepted: 03/25/2022] [Indexed: 12/11/2022] Open
Abstract
The nonsense-mediated mRNA decay (NMD) pathway monitors translation termination in order to degrade transcripts with premature stop codons and regulate thousands of human genes. Here, we show that an alternative mammalian-specific isoform of the core NMD factor UPF1, termed UPF1LL , enables condition-dependent remodeling of NMD specificity. Previous studies indicate that the extension of a conserved regulatory loop in the UPF1LL helicase core confers a decreased propensity to dissociate from RNA upon ATP hydrolysis relative to UPF1SL , the major UPF1 isoform. Using biochemical and transcriptome-wide approaches, we find that UPF1LL can circumvent the protective RNA binding proteins PTBP1 and hnRNP L to preferentially bind and down-regulate transcripts with long 3'UTRs normally shielded from NMD. Unexpectedly, UPF1LL supports induction of NMD on new populations of substrate mRNAs in response to activation of the integrated stress response and impaired translation efficiency. Thus, while canonical NMD is abolished by moderate translational repression, UPF1LL activity is enhanced, offering the possibility to rapidly rewire NMD specificity in response to cellular stress.
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Affiliation(s)
- Sarah E Fritz
- Biochemistry and Biophysics CenterNational Heart, Lung, and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Soumya Ranganathan
- Biochemistry and Biophysics CenterNational Heart, Lung, and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - Clara D Wang
- Biochemistry and Biophysics CenterNational Heart, Lung, and Blood InstituteNational Institutes of HealthBethesdaMDUSA
| | - J Robert Hogg
- Biochemistry and Biophysics CenterNational Heart, Lung, and Blood InstituteNational Institutes of HealthBethesdaMDUSA
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31
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Mailliot J, Vivoli-Vega M, Schaffitzel C. No-nonsense: insights into the functional interplay of nonsense-mediated mRNA decay factors. Biochem J 2022; 479:973-993. [PMID: 35551602 PMCID: PMC9162471 DOI: 10.1042/bcj20210556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 04/10/2022] [Accepted: 04/12/2022] [Indexed: 11/22/2022]
Abstract
Nonsense-mediated messenger RNA decay (NMD) represents one of the main surveillance pathways used by eukaryotic cells to control the quality and abundance of mRNAs and to degrade viral RNA. NMD recognises mRNAs with a premature termination codon (PTC) and targets them to decay. Markers for a mRNA with a PTC, and thus NMD, are a long a 3'-untranslated region and the presence of an exon-junction complex (EJC) downstream of the stop codon. Here, we review our structural understanding of mammalian NMD factors and their functional interplay leading to a branched network of different interconnected but specialised mRNA decay pathways. We discuss recent insights into the potential impact of EJC composition on NMD pathway choice. We highlight the coexistence and function of different isoforms of up-frameshift protein 1 (UPF1) with an emphasis of their role at the endoplasmic reticulum and during stress, and the role of the paralogs UPF3B and UPF3A, underscoring that gene regulation by mammalian NMD is tightly controlled and context-dependent being conditional on developmental stage, tissue and cell types.
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Affiliation(s)
- Justine Mailliot
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K
| | - Mirella Vivoli-Vega
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K
| | - Christiane Schaffitzel
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, U.K
- Bristol Synthetic Biology Centre BrisSynBio, 24 Tyndall Ave, Bristol BS8 1TQ, U.K
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32
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Sanderlin EJ, Keenan MM, Mense M, Revenko AS, Monia BP, Guo S, Huang L. CFTR mRNAs with nonsense codons are degraded by the SMG6-mediated endonucleolytic decay pathway. Nat Commun 2022; 13:2344. [PMID: 35487895 PMCID: PMC9054838 DOI: 10.1038/s41467-022-29935-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 03/24/2022] [Indexed: 12/22/2022] Open
Abstract
Approximately 10% of cystic fibrosis patients harbor nonsense mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which can generate nonsense codons in the CFTR mRNA and subsequently activate the nonsense-mediated decay (NMD) pathway resulting in rapid mRNA degradation. However, it is not known which NMD branches govern the decay of CFTR mRNAs containing nonsense codons. Here we utilize antisense oligonucleotides targeting NMD factors to evaluate the regulation of nonsense codon-containing CFTR mRNAs by the NMD pathway. We observe that CFTR mRNAs with nonsense codons G542X, R1162X, and W1282X, but not Y122X, require UPF2 and UPF3 for NMD. Furthermore, we demonstrate that all evaluated CFTR mRNAs harboring nonsense codons are degraded by the SMG6-mediated endonucleolytic pathway rather than the SMG5-SMG7-mediated exonucleolytic pathway. Finally, we show that upregulation of all evaluated CFTR mRNAs with nonsense codons by NMD pathway inhibition improves outcomes of translational readthrough therapy.
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Affiliation(s)
| | | | - Martin Mense
- Cystic Fibrosis Foundation Therapeutics Lab, Cystic Fibrosis Foundation, Lexington, MA, USA
| | | | | | - Shuling Guo
- Ionis Pharmaceuticals, Inc., Carlsbad, CA, USA
| | - Lulu Huang
- Ionis Pharmaceuticals, Inc., Carlsbad, CA, USA.
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33
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Marques AR, Santos JX, Martiniano H, Vilela J, Rasga C, Romão L, Vicente AM. Gene Variants Involved in Nonsense-Mediated mRNA Decay Suggest a Role in Autism Spectrum Disorder. Biomedicines 2022; 10:biomedicines10030665. [PMID: 35327467 PMCID: PMC8945030 DOI: 10.3390/biomedicines10030665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/04/2022] [Accepted: 03/07/2022] [Indexed: 02/07/2023] Open
Abstract
Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition with unclear etiology. Many genes have been associated with ASD risk, but the underlying mechanisms are still poorly understood. An important post-transcriptional regulatory mechanism that plays an essential role during neurodevelopment, the Nonsense-Mediated mRNA Decay (NMD) pathway, may contribute to ASD risk. In this study, we gathered a list of 46 NMD factors and regulators and investigated the role of genetic variants in these genes in ASD. By conducting a comprehensive search for Single Nucleotide Variants (SNVs) in NMD genes using Whole Exome Sequencing data from 1828 ASD patients, we identified 270 SNVs predicted to be damaging in 28.7% of the population. We also analyzed Copy Number Variants (CNVs) from two cohorts of ASD patients (N = 3570) and discovered 38 CNVs in 1% of cases. Importantly, we discovered 136 genetic variants (125 SNVs and 11 CNVs) in 258 ASD patients that were located within protein domains required for NMD. These gene variants are classified as damaging using in silico prediction tools, and therefore may interfere with proper NMD function in ASD. The discovery of NMD genes as candidates for ASD in large patient genomic datasets provides evidence supporting the involvement of the NMD pathway in ASD pathophysiology.
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Affiliation(s)
- Ana Rita Marques
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
| | - João Xavier Santos
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
| | - Hugo Martiniano
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
| | - Joana Vilela
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
| | - Célia Rasga
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
| | - Luísa Romão
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal
| | - Astrid Moura Vicente
- Departamento de Promoção da Saúde e Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Avenida Padre Cruz, 1649-016 Lisboa, Portugal; (A.R.M.); (J.X.S.); (H.M.); (J.V.); (C.R.)
- BioISI-Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisboa, Campo Grande, C8, 1749-016 Lisboa, Portugal;
- Correspondence:
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34
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Gilbert A, Saveanu C. Unusual SMG suspects recruit degradation enzymes in nonsense-mediated mRNA decay. Bioessays 2022; 44:e2100296. [PMID: 35266563 DOI: 10.1002/bies.202100296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 02/27/2022] [Accepted: 03/02/2022] [Indexed: 11/09/2022]
Abstract
Degradation of eukaryotic RNAs that contain premature termination codons (PTC) during nonsense-mediated mRNA decay (NMD) is initiated by RNA decapping or endonucleolytic cleavage driven by conserved factors. Models for NMD mechanisms, including recognition of PTCs or the timing and role of protein phosphorylation for RNA degradation are challenged by new results. For example, the depletion of the SMG5/7 heterodimer, thought to activate RNA degradation by decapping, leads to a phenotype showing a defect of endonucleolytic activity of NMD complexes. This phenotype is not correlated to a decreased binding of the endonuclease SMG6 with the core NMD factor UPF1, suggesting that it is the result of an imbalance between active (e.g., in polysomes) and inactive (e.g., in RNA-protein condensates) states of NMD complexes. Such imbalance between multiple complexes is not restricted to NMD and should be taken into account when establishing causal links between gene function perturbation and observed phenotypes.
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Affiliation(s)
- Agathe Gilbert
- Institut Pasteur, Sorbonne Université, CNRS UMR-3525, Paris, F-75015, France
| | - Cosmin Saveanu
- Institut Pasteur, Sorbonne Université, CNRS UMR-3525, Paris, F-75015, France
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35
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Nsengimana B, Khan FA, Ngowi EE, Zhou X, Jin Y, Jia Y, Wei W, Ji S. Processing body (P-body) and its mediators in cancer. Mol Cell Biochem 2022; 477:1217-1238. [PMID: 35089528 DOI: 10.1007/s11010-022-04359-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/11/2022] [Indexed: 12/24/2022]
Abstract
In recent years, processing bodies (P-bodies) formed by liquid-liquid phase separation, have attracted growing scientific attention due to their involvement in numerous cellular activities, including the regulation of mRNAs decay or storage. These cytoplasmic dynamic membraneless granules contain mRNA storage and decay components such as deadenylase and decapping factors. In addition, different mRNA metabolic regulators, including m6A readers and gene-mediated miRNA-silencing, are also associated with such P-bodies. Cancerous cells may profit from these mRNA decay shredders by up-regulating the expression level of oncogenes and down-regulating tumor suppressor genes. The main challenges of cancer treatment are drug resistance, metastasis, and cancer relapse likely associated with cancer stem cells, heterogeneity, and plasticity features of different tumors. The mRNA metabolic regulators based on P-bodies play a great role in cancer development and progression. The dysregulation of P-bodies mediators affects mRNA metabolism. However, less is known about the relationship between P-bodies mediators and cancerous behavior. The current review summarizes the recent studies on P-bodies mediators, their contribution to tumor development, and their potential in the clinical setting, particularly highlighting the P-bodies as potential drug-carriers such as exosomes to anticancer in the future.
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Affiliation(s)
- Bernard Nsengimana
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China
| | - Faiz Ali Khan
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China
| | - Ebenezeri Erasto Ngowi
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China
| | - Xuefeng Zhou
- Department of Oncology, Dongtai Affiliated Hospital of Nantong University, Dongtai, 224200, Jiangsu, People's Republic of China
| | - Yu Jin
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China
| | - Yuting Jia
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China
| | - Wenqiang Wei
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China.
| | - Shaoping Ji
- Laboratory of Cell Signal Transduction, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Henan University, Henan, 475004, People's Republic of China.
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36
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Lejeune F. Nonsense-Mediated mRNA Decay, a Finely Regulated Mechanism. Biomedicines 2022; 10:biomedicines10010141. [PMID: 35052820 PMCID: PMC8773229 DOI: 10.3390/biomedicines10010141] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 02/01/2023] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is both a mechanism for rapidly eliminating mRNAs carrying a premature termination codon and a pathway that regulates many genes. This implies that NMD must be subject to regulation in order to allow, under certain physiological conditions, the expression of genes that are normally repressed by NMD. Therapeutically, it might be interesting to express certain NMD-repressed genes or to allow the synthesis of functional truncated proteins. Developing such approaches will require a good understanding of NMD regulation. This review describes the different levels of this regulation in human cells.
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Affiliation(s)
- Fabrice Lejeune
- Univ. Lille, CNRS, Inserm, CHU Lille, UMR9020-U1277—CANTHER—Cancer Heterogeneity Plasticity and Resistance to Therapies, F-59000 Lille, France;
- Unité Tumorigenèse et Résistance aux Traitements, Institut Pasteur de Lille, F-59000 Lille, France
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37
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Abstract
Nonsense-mediated mRNA decay (NMD) is an mRNA degradation pathway that eliminates transcripts containing premature termination codons (PTCs). Half-lives of the mRNAs containing PTCs demonstrate that a small percent escape surveillance and do not degrade. It is not known whether this escape represents variable mRNA degradation within cells or, alternatively cells within the population are resistant. Here we demonstrate a single-cell approach with a bi-directional reporter, which expresses two β-globin genes with or without a PTC in the same cell, to characterize the efficiency of NMD in individual cells. We found a broad range of NMD efficiency in the population; some cells degraded essentially all of the mRNAs, while others escaped NMD almost completely. Characterization of NMD efficiency together with NMD regulators in single cells showed cell-to-cell variability of NMD reflects the differential level of surveillance factors, SMG1 and phosphorylated UPF1. A single-cell fluorescent reporter system that enabled detection of NMD using flow cytometry revealed that this escape occurred either by translational readthrough at the PTC or by a failure of mRNA degradation after successful translation termination at the PTC.
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38
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Chu V, Feng Q, Lim Y, Shao S. Selective destabilization of polypeptides synthesized from NMD-targeted transcripts. Mol Biol Cell 2021; 32:ar38. [PMID: 34586879 PMCID: PMC8694075 DOI: 10.1091/mbc.e21-08-0382] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The translation of mRNAs that contain a premature termination codon (PTC) generates truncated proteins that may have toxic dominant negative effects. Nonsense-mediated decay (NMD) is an mRNA surveillance pathway that degrades PTC-containing mRNAs to limit the production of truncated proteins. NMD activation requires a ribosome terminating translation at a PTC, but what happens to the polypeptides synthesized during the translation cycle needed to activate NMD is incompletely understood. Here, by establishing reporter systems that encode the same polypeptide sequence before a normal termination codon or PTC, we show that termination of protein synthesis at a PTC is sufficient to selectively destabilize polypeptides in mammalian cells. Proteasome inhibition specifically rescues the levels of nascent polypeptides produced from PTC-containing mRNAs within an hour, but also disrupts mRNA homeostasis within a few hours. PTC-terminated polypeptide destabilization is also alleviated by depleting the central NMD factor UPF1 or SMG1, the kinase that phosphorylates UPF1 to activate NMD, but not by inhibiting SMG1 kinase activity. Our results suggest that polypeptide degradation is linked to PTC recognition in mammalian cells and clarify a framework to investigate these mechanisms.
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Affiliation(s)
- Vincent Chu
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Qing Feng
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115
| | - Yang Lim
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115
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Rotaviral nonstructural protein 5 (NSP5) promotes proteasomal degradation of up-frameshift protein 1 (UPF1), a principal mediator of nonsense-mediated mRNA decay (NMD) pathway, to facilitate infection. Cell Signal 2021; 89:110180. [PMID: 34718106 DOI: 10.1016/j.cellsig.2021.110180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 10/22/2021] [Accepted: 10/25/2021] [Indexed: 11/23/2022]
Abstract
Nonsense-mediated mRNA decay (NMD), a cellular RNA quality system, has been shown to be an ancestral form of cellular antiviral response that can restrict viral infection by targeting viral RNA for degradation or other various mechanisms. In support to this hypothesis, emerging evidences unraveled that viruses have evolved numerous mechanisms to circumvent or modulate the NMD pathway to ensure unhindered replication within the host cell. In this study, we investigated the potential interplay between the cellular NMD pathway and rotavirus (RV). Our data suggested that rotavirus infection resulted in global inhibition of NMD pathway by downregulating the expression of UPF1 in a strain independent manner. UPF1 expression was found to be regulated at the post-transcriptional level by ubiquitin-proteasome mediated degradation pathway. Subsequent studies revealed rotaviral non-structural protein 5 (NSP5) associates with UPF1 and promotes its cullin-dependent proteasome mediated degradation. Furthermore, ectopic expression of UPF1 during RV infection resulted in reduced expression of viral proteins and viral RNAs leading to diminished production of infective rotavirus particles, suggesting the anti-rotaviral role of UPF1. Finally, the delayed degradation kinetics of transfected rotaviral RNA in UPF1 and UPF2 depleted cells and the association of UPF1 and UPF2 with viral RNAs suggested that NMD targets rotaviral RNAs for degradation. Collectively, the present study demonstrates the antiviral role of NMD pathway during rotavirus infection and also reveals the underlying mechanism by which rotavirus overwhelms NMD pathway to establish successful replication.
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40
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Zinshteyn B, Sinha NK, Enam SU, Koleske B, Green R. Translational repression of NMD targets by GIGYF2 and EIF4E2. PLoS Genet 2021; 17:e1009813. [PMID: 34665823 PMCID: PMC8555832 DOI: 10.1371/journal.pgen.1009813] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 10/29/2021] [Accepted: 09/08/2021] [Indexed: 12/26/2022] Open
Abstract
Translation of messenger RNAs (mRNAs) with premature termination codons produces truncated proteins with potentially deleterious effects. This is prevented by nonsense-mediated mRNA decay (NMD) of these mRNAs. NMD is triggered by ribosomes terminating upstream of a splice site marked by an exon-junction complex (EJC), but also acts on many mRNAs lacking a splice junction after their termination codon. We developed a genome-wide CRISPR flow cytometry screen to identify regulators of mRNAs with premature termination codons in K562 cells. This screen recovered essentially all core NMD factors and suggested a role for EJC factors in degradation of PTCs without downstream splicing. Among the strongest hits were the translational repressors GIGYF2 and EIF4E2. GIGYF2 and EIF4E2 mediate translational repression but not mRNA decay of a subset of NMD targets and interact with NMD factors genetically and physically. Our results suggest a model wherein recognition of a stop codon as premature can lead to its translational repression through GIGYF2 and EIF4E2.
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Affiliation(s)
- Boris Zinshteyn
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Niladri K. Sinha
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Syed Usman Enam
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Benjamin Koleske
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
| | - Rachel Green
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States of America
- * E-mail:
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41
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Lu YY, Krebber H. Nuclear mRNA Quality Control and Cytoplasmic NMD Are Linked by the Guard Proteins Gbp2 and Hrb1. Int J Mol Sci 2021; 22:ijms222011275. [PMID: 34681934 PMCID: PMC8541090 DOI: 10.3390/ijms222011275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/13/2021] [Accepted: 10/17/2021] [Indexed: 12/23/2022] Open
Abstract
Pre-mRNA splicing is critical for cells, as defects in this process can lead to altered open reading frames and defective proteins, potentially causing neurodegenerative diseases and cancer. Introns are removed in the nucleus and splicing is documented by the addition of exon-junction-complexes (EJCs) at exon-exon boundaries. This “memory” of splicing events is important for the ribosome, which translates the RNAs in the cytoplasm. In case a stop codon was detected before an EJC, translation is blocked and the RNA is eliminated by the nonsense-mediated decay (NMD). In the model organism Saccharomyces cerevisiae, two guard proteins, Gbp2 and Hrb1, have been identified as nuclear quality control factors for splicing. In their absence, intron-containing mRNAs leak into the cytoplasm. Their presence retains transcripts until the process is completed and they release the mRNAs by recruitment of the export factor Mex67. On transcripts that experience splicing problems, these guard proteins recruit the nuclear RNA degradation machinery. Interestingly, they continue their quality control function on exported transcripts. They support NMD by inhibiting translation and recruiting the cytoplasmic degradation factors. In this way, they link the nuclear and cytoplasmic quality control systems. These discoveries are also intriguing for humans, as homologues of these guard proteins are present also in multicellular organisms. Here, we provide an overview of the quality control mechanisms of pre-mRNA splicing, and present Gbp2 and Hrb1, as well as their human counterparts, as important players in these pathways.
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A CENH3 mutation promotes meiotic exit and restores fertility in SMG7-deficient Arabidopsis. PLoS Genet 2021; 17:e1009779. [PMID: 34591845 PMCID: PMC8509889 DOI: 10.1371/journal.pgen.1009779] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 10/12/2021] [Accepted: 08/16/2021] [Indexed: 01/21/2023] Open
Abstract
Meiosis in angiosperm plants is followed by mitotic divisions to form multicellular haploid gametophytes. Termination of meiosis and transition to gametophytic development is, in Arabidopsis, governed by a dedicated mechanism that involves SMG7 and TDM1 proteins. Mutants carrying the smg7-6 allele are semi-fertile due to reduced pollen production. We found that instead of forming tetrads, smg7-6 pollen mother cells undergo multiple rounds of chromosome condensation and spindle assembly at the end of meiosis, resembling aberrant attempts to undergo additional meiotic divisions. A suppressor screen uncovered a mutation in centromeric histone H3 (CENH3) that increased fertility and promoted meiotic exit in smg7-6 plants. The mutation led to inefficient splicing of the CENH3 mRNA and a substantial decrease of CENH3, resulting in smaller centromeres. The reduced level of CENH3 delayed formation of the mitotic spindle but did not have an apparent effect on plant growth and development. We suggest that impaired spindle re-assembly at the end of meiosis limits aberrant divisions in smg7-6 plants and promotes formation of tetrads and viable pollen. Furthermore, the mutant with reduced level of CENH3 was very inefficient haploid inducer indicating that differences in centromere size is not the key determinant of centromere-mediated genome elimination. Meiosis is a reductional cell division that halves number of chromosomes during two successive rounds of chromosome segregation without intervening DNA replication. Such mode of chromosome segregation requires extensive reprogramming of the cell division machinery at the entry to meiosis, and inactivation of the meiotic program upon the formation of haploid spores. Here we showed that Arabidopsis partially deficient in the RNA decay factor SMG7 fail to exit meiosis and continue with attempts to undergo additional cycles of post-meiotic chromosome segregations without genome replication. This results in a reduced number of viable pollen and diminished fertility. To find genes involved in meiotic exit, we performed a suppressor screen for the SMG7-deicient plants that re-gain fertility. We found that reducing the amount of centromeric histone partially restores pollen formation and fertility in smg7 mutants. This is likely due to inefficient formation of centromere-microtubule interactions that impairs spindle reassembly and re-entry into aberrant rounds of post-meiotic chromosome segregation.
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43
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UPF1: From mRNA Surveillance to Protein Quality Control. Biomedicines 2021; 9:biomedicines9080995. [PMID: 34440199 PMCID: PMC8392595 DOI: 10.3390/biomedicines9080995] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/03/2021] [Accepted: 08/05/2021] [Indexed: 12/20/2022] Open
Abstract
Selective recognition and removal of faulty transcripts and misfolded polypeptides are crucial for cell viability. In eukaryotic cells, nonsense-mediated mRNA decay (NMD) constitutes an mRNA surveillance pathway for sensing and degrading aberrant transcripts harboring premature termination codons (PTCs). NMD functions also as a post-transcriptional gene regulatory mechanism by downregulating naturally occurring mRNAs. As NMD is activated only after a ribosome reaches a PTC, PTC-containing mRNAs inevitably produce truncated and potentially misfolded polypeptides as byproducts. To cope with the emergence of misfolded polypeptides, eukaryotic cells have evolved sophisticated mechanisms such as chaperone-mediated protein refolding, rapid degradation of misfolded polypeptides through the ubiquitin–proteasome system, and sequestration of misfolded polypeptides to the aggresome for autophagy-mediated degradation. In this review, we discuss how UPF1, a key NMD factor, contributes to the selective removal of faulty transcripts via NMD at the molecular level. We then highlight recent advances on UPF1-mediated communication between mRNA surveillance and protein quality control.
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Chen Y, Khazina E, Izaurralde E, Weichenrieder O. Crystal structure and functional properties of the human CCR4-CAF1 deadenylase complex. Nucleic Acids Res 2021; 49:6489-6510. [PMID: 34038562 PMCID: PMC8216464 DOI: 10.1093/nar/gkab414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 04/28/2021] [Accepted: 05/05/2021] [Indexed: 01/07/2023] Open
Abstract
The CCR4 and CAF1 deadenylases physically interact to form the CCR4-CAF1 complex and function as the catalytic core of the larger CCR4-NOT complex. Together, they are responsible for the eventual removal of the 3′-poly(A) tail from essentially all cellular mRNAs and consequently play a central role in the posttranscriptional regulation of gene expression. The individual properties of CCR4 and CAF1, however, and their respective contributions in different organisms and cellular environments are incompletely understood. Here, we determined the crystal structure of a human CCR4-CAF1 complex and characterized its enzymatic and substrate recognition properties. The structure reveals specific molecular details affecting RNA binding and hydrolysis, and confirms the CCR4 nuclease domain to be tethered flexibly with a considerable distance between both enzyme active sites. CCR4 and CAF1 sense nucleotide identity on both sides of the 3′-terminal phosphate, efficiently differentiating between single and consecutive non-A residues. In comparison to CCR4, CAF1 emerges as a surprisingly tunable enzyme, highly sensitive to pH, magnesium and zinc ions, and possibly allowing distinct reaction geometries. Our results support a picture of CAF1 as a primordial deadenylase, which gets assisted by CCR4 for better efficiency and by the assembled NOT proteins for selective mRNA targeting and regulation.
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Affiliation(s)
- Ying Chen
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elena Khazina
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Elisa Izaurralde
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
| | - Oliver Weichenrieder
- Department of Biochemistry, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, D-72076 Tübingen, Germany
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45
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SMG5-SMG7 authorize nonsense-mediated mRNA decay by enabling SMG6 endonucleolytic activity. Nat Commun 2021; 12:3965. [PMID: 34172724 PMCID: PMC8233366 DOI: 10.1038/s41467-021-24046-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 05/30/2021] [Indexed: 12/28/2022] Open
Abstract
Eukaryotic gene expression is constantly controlled by the translation-coupled nonsense-mediated mRNA decay (NMD) pathway. Aberrant translation termination leads to NMD activation, resulting in phosphorylation of the central NMD factor UPF1 and robust clearance of NMD targets via two seemingly independent and redundant mRNA degradation branches. Here, we uncover that the loss of the first SMG5-SMG7-dependent pathway also inactivates the second SMG6-dependent branch, indicating an unexpected functional connection between the final NMD steps. Transcriptome-wide analyses of SMG5-SMG7-depleted cells confirm exhaustive NMD inhibition resulting in massive transcriptomic alterations. Intriguingly, we find that the functionally underestimated SMG5 can substitute the role of SMG7 and individually activate NMD. Furthermore, the presence of either SMG5 or SMG7 is sufficient to support SMG6-mediated endonucleolysis of NMD targets. Our data support an improved model for NMD execution that features two-factor authentication involving UPF1 phosphorylation and SMG5-SMG7 recruitment to access SMG6 activity. Degradation of nonsense mediated mRNA decay (NMD) substrates is carried out by two seemingly independent pathways, SMG6-mediated endonucleolytic cleavage and/or SMG5-SMG7-induced accelerated deadenylation. Here the authors show that SMG5-SMG7 maintain NMD activity by permitting SMG6 activation.
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46
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Akiyama T, Suzuki T, Yamamoto T. RNA decay machinery safeguards immune cell development and immunological responses. Trends Immunol 2021; 42:447-460. [PMID: 33858774 DOI: 10.1016/j.it.2021.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 12/30/2022]
Abstract
mRNA decay systems control mRNA abundance by counterbalancing transcription. Several recent studies show that mRNA decay pathways are crucial to conventional T and B cell development in vertebrates, in addition to suppressing autoimmunity and excessive inflammatory responses. Selective mRNA degradation triggered by the CCR4-NOT deadenylase complex appears to be required in lymphocyte development, cell quiescence, V(D)J (variable-diversity-joining) recombination, and prevention of inappropriate apoptosis in mice. Moreover, a recent study suggests that mRNA decay may be involved in preventing human hyperinflammatory disease. These findings imply that mRNA decay pathways in humans and mice do not simply maintain mRNA homeostatic turnover but can also precisely regulate immune development and immunological responses by selectively targeting mRNAs.
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Affiliation(s)
- Taishin Akiyama
- Laboratory for Immune Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Graduate School of Medical Life Science, Yokohama City University, Yokohama 230-0045, Japan.
| | - Toru Suzuki
- Laboratory for Immunogenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Tadashi Yamamoto
- Laboratory for Immunogenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan; Cell Signal Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan
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47
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Enwerem III, Elrod ND, Chang CT, Lin A, Ji P, Bohn JA, Levdansky Y, Wagner EJ, Valkov E, Goldstrohm AC. Human Pumilio proteins directly bind the CCR4-NOT deadenylase complex to regulate the transcriptome. RNA (NEW YORK, N.Y.) 2021; 27:445-464. [PMID: 33397688 PMCID: PMC7962487 DOI: 10.1261/rna.078436.120] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 12/28/2020] [Indexed: 05/13/2023]
Abstract
Pumilio paralogs, PUM1 and PUM2, are sequence-specific RNA-binding proteins that are essential for vertebrate development and neurological functions. PUM1&2 negatively regulate gene expression by accelerating degradation of specific mRNAs. Here, we determined the repression mechanism and impact of human PUM1&2 on the transcriptome. We identified subunits of the CCR4-NOT (CNOT) deadenylase complex required for stable interaction with PUM1&2 and to elicit CNOT-dependent repression. Isoform-level RNA sequencing revealed broad coregulation of target mRNAs through the PUM-CNOT repression mechanism. Functional dissection of the domains of PUM1&2 identified a conserved amino-terminal region that confers the predominant repressive activity via direct interaction with CNOT. In addition, we show that the mRNA decapping enzyme, DCP2, has an important role in repression by PUM1&2 amino-terminal regions. Our results support a molecular model of repression by human PUM1&2 via direct recruitment of CNOT deadenylation machinery in a decapping-dependent mRNA decay pathway.
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Affiliation(s)
- Isioma I I Enwerem
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Nathan D Elrod
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77550, USA
| | - Chung-Te Chang
- Department of Biochemistry, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Ai Lin
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77550, USA
| | - Ping Ji
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77550, USA
| | - Jennifer A Bohn
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yevgen Levdansky
- Department of Biochemistry, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch at Galveston, Galveston, Texas 77550, USA
| | - Eugene Valkov
- Department of Biochemistry, Max Planck Institute for Developmental Biology, 72076 Tübingen, Germany
| | - Aaron C Goldstrohm
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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48
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García-Moreno JF, Romão L. Perspective in Alternative Splicing Coupled to Nonsense-Mediated mRNA Decay. Int J Mol Sci 2020; 21:ijms21249424. [PMID: 33321981 PMCID: PMC7764535 DOI: 10.3390/ijms21249424] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 12/19/2022] Open
Abstract
Alternative splicing (AS) of precursor mRNA (pre-mRNA) is a cellular post-transcriptional process that generates protein isoform diversity. Nonsense-mediated RNA decay (NMD) is an mRNA surveillance pathway that recognizes and selectively degrades transcripts containing premature translation-termination codons (PTCs), thereby preventing the production of truncated proteins. Nevertheless, NMD also fine-tunes the gene expression of physiological mRNAs encoding full-length proteins. Interestingly, around one third of all AS events results in PTC-containing transcripts that undergo NMD. Numerous studies have reported a coordinated action between AS and NMD, in order to regulate the expression of several genes, especially those coding for RNA-binding proteins (RBPs). This coupling of AS to NMD (AS-NMD) is considered a gene expression tool that controls the ratio of productive to unproductive mRNA isoforms, ultimately degrading PTC-containing non-functional mRNAs. In this review, we focus on the mechanisms underlying AS-NMD, and how this regulatory process is able to control the homeostatic expression of numerous RBPs, including splicing factors, through auto- and cross-regulatory feedback loops. Furthermore, we discuss the importance of AS-NMD in the regulation of biological processes, such as cell differentiation. Finally, we analyze interesting recent data on the relevance of AS-NMD to human health, covering its potential roles in cancer and other disorders.
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Affiliation(s)
- Juan F. García-Moreno
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal;
- Faculty of Science, BioISI—Biosystems and Integrative Sciences Institute, University of Lisboa, 1749-016 Lisboa, Portugal
| | - Luísa Romão
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016 Lisboa, Portugal;
- Faculty of Science, BioISI—Biosystems and Integrative Sciences Institute, University of Lisboa, 1749-016 Lisboa, Portugal
- Correspondence: ; Tel.: +351-217-508-155
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49
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Annibaldis G, Domanski M, Dreos R, Contu L, Carl S, Kläy N, Mühlemann O. Readthrough of stop codons under limiting ABCE1 concentration involves frameshifting and inhibits nonsense-mediated mRNA decay. Nucleic Acids Res 2020; 48:10259-10279. [PMID: 32941650 PMCID: PMC7544199 DOI: 10.1093/nar/gkaa758] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 08/28/2020] [Accepted: 09/09/2020] [Indexed: 12/11/2022] Open
Abstract
To gain insight into the mechanistic link between translation termination and nonsense-mediated mRNA decay (NMD), we depleted the ribosome recycling factor ABCE1 in human cells, resulting in an upregulation of NMD-sensitive mRNAs. Suppression of NMD on these mRNAs occurs prior to their SMG6-mediated endonucleolytic cleavage. ABCE1 depletion caused ribosome stalling at termination codons (TCs) and increased ribosome occupancy in 3′ UTRs, implying enhanced TC readthrough. ABCE1 knockdown indeed increased the rate of readthrough and continuation of translation in different reading frames, providing a possible explanation for the observed NMD inhibition, since enhanced readthrough displaces NMD activating proteins from the 3′ UTR. Our results indicate that stalling at TCs triggers ribosome collisions and activates ribosome quality control. Collectively, we show that improper translation termination can lead to readthrough of the TC, presumably due to ribosome collisions pushing the stalled ribosomes into the 3′ UTR, where it can resume translation in-frame as well as out-of-frame.
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Affiliation(s)
- Giuditta Annibaldis
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Mittelstrasse 43, CH-3012 Bern, Switzerland
| | - Michal Domanski
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - René Dreos
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Lara Contu
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.,Graduate School for Cellular and Biomedical Sciences, University of Bern, Mittelstrasse 43, CH-3012 Bern, Switzerland
| | - Sarah Carl
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - Nina Kläy
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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50
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The Regulatory Properties of the Ccr4-Not Complex. Cells 2020; 9:cells9112379. [PMID: 33138308 PMCID: PMC7692201 DOI: 10.3390/cells9112379] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/21/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022] Open
Abstract
The mammalian Ccr4–Not complex, carbon catabolite repression 4 (Ccr4)-negative on TATA-less (Not), is a large, highly conserved, multifunctional assembly of proteins that acts at different cellular levels to regulate gene expression. In the nucleus, it is involved in the regulation of the cell cycle, chromatin modification, activation and inhibition of transcription initiation, control of transcription elongation, RNA export, nuclear RNA surveillance, and DNA damage repair. In the cytoplasm, the Ccr4–Not complex plays a central role in mRNA decay and affects protein quality control. Most of our original knowledge of the Ccr4–Not complex is derived, primarily, from studies in yeast. More recent studies have shown that the mammalian complex has a comparable structure and similar properties. In this review, we summarize the evidence for the multiple roles of both the yeast and mammalian Ccr4–Not complexes, highlighting their similarities.
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