1
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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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2
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Andjus S, Szachnowski U, Vogt N, Gioftsidi S, Hatin I, Cornu D, Papadopoulos C, Lopes A, Namy O, Wery M, Morillon A. Pervasive translation of Xrn1-sensitive unstable long noncoding RNAs in yeast. RNA (NEW YORK, N.Y.) 2024; 30:662-679. [PMID: 38443115 PMCID: PMC11098462 DOI: 10.1261/rna.079903.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 02/15/2024] [Indexed: 03/07/2024]
Abstract
Despite being predicted to lack coding potential, cytoplasmic long noncoding (lnc)RNAs can associate with ribosomes. However, the landscape and biological relevance of lncRNA translation remain poorly studied. In yeast, cytoplasmic Xrn1-sensitive unstable transcripts (XUTs) are targeted by nonsense-mediated mRNA decay (NMD), suggesting a translation-dependent degradation process. Here, we report that XUTs are pervasively translated, which impacts their decay. We show that XUTs globally accumulate upon translation elongation inhibition, but not when initial ribosome loading is impaired. Ribo-seq confirmed ribosomes binding to XUTs and identified ribosome-associated 5'-proximal small ORFs. Mechanistically, the NMD-sensitivity of XUTs mainly depends on the 3'-untranslated region length. Finally, we show that the peptide resulting from the translation of an NMD-sensitive XUT reporter exists in NMD-competent cells. Our work highlights the role of translation in the posttranscriptional metabolism of XUTs. We propose that XUT-derived peptides could be exposed to natural selection, while NMD restricts XUT levels.
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Affiliation(s)
- Sara Andjus
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, PSL University, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
| | - Ugo Szachnowski
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
| | - Nicolas Vogt
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
| | - Stamatia Gioftsidi
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
| | - Isabelle Hatin
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - David Cornu
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Chris Papadopoulos
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Anne Lopes
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Olivier Namy
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - Maxime Wery
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
| | - Antonin Morillon
- ncRNA, Epigenetic and Genome Fluidity, Institut Curie, Sorbonne Université, CNRS UMR3244, F-75248 Paris Cedex 05, France
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3
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Premchandar A, Ming R, Baiad A, Da Fonte DF, Xu H, Faubert D, Veit G, Lukacs GL. Readthrough-induced misincorporated amino acid ratios guide mutant-specific therapeutic approaches for two CFTR nonsense mutations. Front Pharmacol 2024; 15:1389586. [PMID: 38725656 PMCID: PMC11079177 DOI: 10.3389/fphar.2024.1389586] [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: 02/21/2024] [Accepted: 03/28/2024] [Indexed: 05/12/2024] Open
Abstract
Cystic fibrosis (CF) is a monogenic disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Premature termination codons (PTCs) represent ∼9% of CF mutations that typically cause severe expression defects of the CFTR anion channel. Despite the prevalence of PTCs as the underlying cause of genetic diseases, understanding the therapeutic susceptibilities of their molecular defects, both at the transcript and protein levels remains partially elucidated. Given that the molecular pathologies depend on the PTC positions in CF, multiple pharmacological interventions are required to suppress the accelerated nonsense-mediated mRNA decay (NMD), to correct the CFTR conformational defect caused by misincorporated amino acids, and to enhance the inefficient stop codon readthrough. The G418-induced readthrough outcome was previously investigated only in reporter models that mimic the impact of the local sequence context on PTC mutations in CFTR. To identify the misincorporated amino acids and their ratios for PTCs in the context of full-length CFTR readthrough, we developed an affinity purification (AP)-tandem mass spectrometry (AP-MS/MS) pipeline. We confirmed the incorporation of Cys, Arg, and Trp residues at the UGA stop codons of G542X, R1162X, and S1196X in CFTR. Notably, we observed that the Cys and Arg incorporation was favored over that of Trp into these CFTR PTCs, suggesting that the transcript sequence beyond the proximity of PTCs and/or other factors can impact the amino acid incorporation and full-length CFTR functional expression. Additionally, establishing the misincorporated amino acid ratios in the readthrough CFTR PTCs aided in maximizing the functional rescue efficiency of PTCs by optimizing CFTR modulator combinations. Collectively, our findings contribute to the understanding of molecular defects underlying various CFTR nonsense mutations and provide a foundation to refine mutation-dependent therapeutic strategies for various CF-causing nonsense mutations.
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Affiliation(s)
| | - Ruiji Ming
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Abed Baiad
- Department of Physiology, McGill University, Montréal, QC, Canada
| | | | - Haijin Xu
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Denis Faubert
- IRCM Mass Spectrometry and Proteomics Platform, Institut de Recherches Cliniques de Montréal, Montréal, QC, Canada
| | - Guido Veit
- Department of Physiology, McGill University, Montréal, QC, Canada
| | - Gergely L. Lukacs
- Department of Physiology, McGill University, Montréal, QC, Canada
- Department of Biochemistry, McGill University, Montréal, QC, Canada
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4
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Kolakada D, Fu R, Biziaev N, Shuvalov A, Lore M, Campbell AE, Cortázar MA, Sajek MP, Hesselberth JR, Mukherjee N, Alkalaeva E, Jagannathan S. Systematic analysis of nonsense variants uncovers peptide release rate as a novel modifier of nonsense-mediated mRNA decay efficiency. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575080. [PMID: 38260612 PMCID: PMC10802582 DOI: 10.1101/2024.01.10.575080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Nonsense variants underlie many genetic diseases. The phenotypic impact of nonsense variants is determined by Nonsense-mediated mRNA decay (NMD), which degrades transcripts with premature termination codons (PTCs). NMD activity varies across transcripts and cellular contexts via poorly understood mechanisms. Here, by leveraging human genetic datasets, we uncover that the amino acid preceding the PTC dramatically affects NMD activity in human cells. We find that glycine codons in particular support high levels of NMD and are enriched before PTCs but depleted before normal termination codons (NTCs). Gly-PTC enrichment is most pronounced in human genes that tolerate loss-of-function variants. This suggests a strong biological impact for Gly-PTC in ensuring robust elimination of potentially toxic truncated proteins from non-essential genes. Biochemical assays revealed that the peptide release rate during translation termination is highly dependent on the identity of the amino acid preceding the stop codon. This release rate is the most critical feature determining NMD activity across our massively parallel reporter assays. Together, we conclude that NMD activity is significantly modulated by the "window of opportunity" offered by translation termination kinetics. Integrating the window of opportunity model with the existing framework of NMD would enable more accurate nonsense variant interpretation in the clinic.
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Affiliation(s)
- Divya Kolakada
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Rui Fu
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Nikita Biziaev
- Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexey Shuvalov
- Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, 119991 Moscow, Russia
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Amy E. Campbell
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Michael A. Cortázar
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Marcin P. Sajek
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Institute of Human Genetics, Polish Academy of Sciences, Poznan, Poland
| | - Jay R. Hesselberth
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Neelanjan Mukherjee
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Elena Alkalaeva
- Engelhardt Institute of Molecular Biology, The Russian Academy of Sciences, 119991 Moscow, Russia
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Lead contact
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5
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Kolakada D, Campbell AE, Galvis LB, Li Z, Lore M, Jagannathan S. A system of reporters for comparative investigation of EJC-independent and EJC-enhanced nonsense-mediated mRNA decay. Nucleic Acids Res 2024; 52:e34. [PMID: 38375914 PMCID: PMC11014337 DOI: 10.1093/nar/gkae121] [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: 06/28/2023] [Revised: 01/05/2024] [Accepted: 02/07/2024] [Indexed: 02/21/2024] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a network of pathways that degrades transcripts that undergo premature translation termination. In mammals, NMD can be divided into the exon junction complex (EJC)-enhanced and EJC-independent branches. Fluorescence- and luminescence-based reporters have long been effective tools to investigate NMD, yet existing reporters largely focus on the EJC-enhanced pathway. Here, we present a system of reporters for comparative studies of EJC-independent and EJC-enhanced NMD. This system also enables the study of NMD-associated outcomes such as premature termination codon (PTC) readthrough and truncated protein degradation. These reporters are compatible with fluorescence or luminescence-based readouts via transient transfection or stable integration. Using this reporter system, we show that EJC-enhanced NMD RNA levels are reduced by 2- or 9-fold and protein levels are reduced by 7- or 12-fold compared to EJC-independent NMD, depending on the reporter gene used. Additionally, the extent of readthrough induced by G418 and an NMD inhibitor (SMG1i), alone and in combination, varies across NMD substrates. When combined, G418 and SMG1i increase readthrough product levels in an additive manner for EJC-independent reporters, while EJC-enhanced reporters show a synergistic effect. We present these reporters as a valuable toolkit to deepen our understanding of NMD and its associated mechanisms.
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Affiliation(s)
- Divya Kolakada
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Amy E Campbell
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Zhongyou Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, 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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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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8
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Kolakada D, Campbell AE, Baquero Galvis L, Li Z, Lore M, Jagannathan S. A system of reporters for comparative investigation of EJC-independent and EJC-enhanced nonsense-mediated mRNA decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567061. [PMID: 38014198 PMCID: PMC10680754 DOI: 10.1101/2023.11.14.567061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a network of pathways that degrades transcripts that undergo premature translation termination. In mammals, NMD can be divided into the exon junction complex (EJC)-enhanced and EJC-independent branches. Fluorescence- and luminescence-based reporters have long been effective tools to investigate NMD, yet existing reporters largely focus on the EJC-enhanced pathway. Here, we present a system of reporters for comparative studies of EJC-independent and EJC-enhanced NMD. This system also enables the study of NMD-associated outcomes such as premature termination codon (PTC) readthrough and truncated protein degradation. These reporters are compatible with fluorescence or luminescence-based readouts via transient transfection or stable integration. Using this reporter system, we show that EJC-enhanced NMD RNA levels are reduced by 2- or 9-fold and protein levels are reduced by 7- or 12-fold compared to EJC-independent NMD, depending on the reporter gene used. Additionally, the extent of readthrough induced by G418 and SMG1i, alone and in combination, varies across NMD substrates. When combined, G418 and SMG1i increase readthrough product levels in an additive manner for EJC-independent reporters, while EJC-enhanced reporters show a synergistic effect. We present these reporters as a valuable toolkit to deepen our understanding of NMD and its associated mechanisms.
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Affiliation(s)
- Divya Kolakada
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Amy E. Campbell
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Laura Baquero Galvis
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Zhongyou Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Mlana Lore
- Molecular Biology Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Sujatha Jagannathan
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
- RNA Bioscience Initiative, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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9
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Holly J, Yewdell JW. Game of Omes: ribosome profiling expands the MHC-I immunopeptidome. Curr Opin Immunol 2023; 83:102342. [PMID: 37247567 PMCID: PMC10524008 DOI: 10.1016/j.coi.2023.102342] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/31/2023]
Abstract
Peptide ligands presented by cell-surface MHC class-I molecules enable T cells to eradicate intracellular pathogens and cancers. The presented peptide repertoire, the class-I immunopeptidome, is generated from each cell's translatome in a highly biased manner to avoid overrepresenting highly abundant translation products. The immunopeptidome can only be defined by mass spectrometry (MS). Here, we review recent advances in immunopeptidomics, focusing on using ribosome profiling as the optimal MS database to optimize the false- and failed-discovery rates and relate these findings to the contribution of defective ribosomal products and cellular quality control mechanisms to MHC class-I antigen processing and presentation.
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Affiliation(s)
- Jaroslav Holly
- Cellular Biology Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jonathan W Yewdell
- Cellular Biology Section, Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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10
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Sun L, Mailliot J, Schaffitzel C. Nonsense-Mediated mRNA Decay Factor Functions in Human Health and Disease. Biomedicines 2023; 11:722. [PMID: 36979701 PMCID: PMC10045457 DOI: 10.3390/biomedicines11030722] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 03/06/2023] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a cellular surveillance mechanism that degrades mRNAs with a premature stop codon, avoiding the synthesis of C-terminally truncated proteins. In addition to faulty mRNAs, NMD recognises ~10% of endogenous transcripts in human cells and downregulates their expression. The up-frameshift proteins are core NMD factors and are conserved from yeast to human in structure and function. In mammals, NMD diversified into different pathways that target different mRNAs employing additional NMD factors. Here, we review our current understanding of molecular mechanisms and cellular roles of NMD pathways and the involvement of more specialised NMD factors. We describe the consequences of mutations in NMD factors leading to neurodevelopmental diseases, and the role of NMD in cancer. We highlight strategies of RNA viruses to evade recognition and decay by the NMD machinery.
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Affiliation(s)
- Lingling Sun
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Justine Mailliot
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Christiane Schaffitzel
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, UK
- Bristol Engineering Biology Centre BrisEngBio, 24 Tyndall Ave, Bristol BS8 1TQ, UK
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11
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Eisenack TJ, Trentini DB. Ending a bad start: Triggers and mechanisms of co-translational protein degradation. Front Mol Biosci 2023; 9:1089825. [PMID: 36660423 PMCID: PMC9846516 DOI: 10.3389/fmolb.2022.1089825] [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: 11/04/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023] Open
Abstract
Proteins are versatile molecular machines that control and execute virtually all cellular processes. They are synthesized in a multilayered process requiring transfer of information from DNA to RNA and finally into polypeptide, with many opportunities for error. In addition, nascent proteins must successfully navigate a complex folding-energy landscape, in which their functional native state represents one of many possible outcomes. Consequently, newly synthesized proteins are at increased risk of misfolding and toxic aggregation. To maintain proteostasis-the state of proteome balance-cells employ a plethora of molecular chaperones that guide proteins along a productive folding pathway and quality control factors that direct misfolded species for degradation. Achieving the correct balance between folding and degradation therefore represents a fundamental task for the proteostasis network. While many chaperones act co-translationally, protein quality control is generally considered to be a post-translational process, as the majority of proteins will only achieve their final native state once translation is completed. Nevertheless, it has been observed that proteins can be ubiquitinated during synthesis. The extent and the relevance of co-translational protein degradation, as well as the underlying molecular mechanisms, remain areas of open investigation. Recent studies made seminal advances in elucidating ribosome-associated quality control processes, and how their loss of function can lead to proteostasis failure and disease. Here, we discuss current understanding of the situations leading to the marking of nascent proteins for degradation before synthesis is completed, and the emerging quality controls pathways engaged in this task in eukaryotic cells. We also highlight the methods used to study co-translational quality control.
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Affiliation(s)
- Tom Joshua Eisenack
- University of Cologne, Faculty of Medicine, University Hospital of Cologne, Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Débora Broch Trentini
- University of Cologne, Faculty of Medicine, University Hospital of Cologne, Center for Molecular Medicine Cologne (CMMC), Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany,*Correspondence: Débora Broch Trentini,
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McKenna MJ, Adams BM, Chu V, Paulo JA, Shao S. ATP13A1 prevents ERAD of folding-competent mislocalized and misoriented proteins. Mol Cell 2022; 82:4277-4289.e10. [PMID: 36283413 PMCID: PMC9675726 DOI: 10.1016/j.molcel.2022.09.035] [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: 04/19/2022] [Revised: 08/18/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022]
Abstract
The biosynthesis of thousands of proteins requires targeting a signal sequence or transmembrane segment (TM) to the endoplasmic reticulum (ER). These hydrophobic ɑ helices must localize to the appropriate cellular membrane and integrate in the correct topology to maintain a high-fidelity proteome. Here, we show that the P5A-ATPase ATP13A1 prevents the accumulation of mislocalized and misoriented proteins, which are eliminated by different ER-associated degradation (ERAD) pathways in mammalian cells. Without ATP13A1, mitochondrial tail-anchored proteins mislocalize to the ER through the ER membrane protein complex and are cleaved by signal peptide peptidase for ERAD. ATP13A1 also facilitates the topogenesis of a subset of proteins with an N-terminal TM or signal sequence that should insert into the ER membrane with a cytosolic N terminus. Without ATP13A1, such proteins accumulate in the wrong orientation and are targeted for ERAD by distinct ubiquitin ligases. Thus, ATP13A1 prevents ERAD of diverse proteins capable of proper folding.
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Affiliation(s)
- Michael J McKenna
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Benjamin M Adams
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Vincent Chu
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, 240 Longwood Ave., Boston, MA 02115, USA.
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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] [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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Udy DB, Bradley RK. Nonsense-mediated mRNA decay uses complementary mechanisms to suppress mRNA and protein accumulation. Life Sci Alliance 2022; 5:e202101217. [PMID: 34880103 PMCID: PMC8711849 DOI: 10.26508/lsa.202101217] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/13/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is an essential, highly conserved quality control pathway that detects and degrades mRNAs containing premature termination codons. Although the essentiality of NMD is frequently ascribed to its prevention of truncated protein accumulation, the extent to which NMD actually suppresses proteins encoded by NMD-sensitive transcripts is less well-understood than NMD-mediated suppression of mRNA. Here, we describe a reporter system that permits accurate quantification of both mRNA and protein levels via stable integration of paired reporters encoding NMD-sensitive and NMD-insensitive transcripts into the AAVS1 safe harbor loci in human cells. We use this system to demonstrate that NMD suppresses proteins encoded by NMD-sensitive transcripts by up to eightfold more than the mRNA itself. Our data indicate that NMD limits the accumulation of proteins encoded by NMD substrates by mechanisms beyond mRNA degradation, such that even when NMD-sensitive mRNAs escape destruction, their encoded proteins are still effectively suppressed.
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Affiliation(s)
- Dylan B Udy
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA, USA
| | - Robert K Bradley
- Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
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