1
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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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2
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Rahmati M, Chebli J, Kumar Banote R, Roselli S, Agholme L, Zetterberg H, Abramsson A. Fine-Tuning Amyloid Precursor Protein Expression through Nonsense-Mediated mRNA Decay. eNeuro 2024; 11:ENEURO.0034-24.2024. [PMID: 38789273 PMCID: PMC11164851 DOI: 10.1523/eneuro.0034-24.2024] [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: 01/24/2024] [Revised: 03/22/2024] [Accepted: 04/16/2024] [Indexed: 05/26/2024] Open
Abstract
Studies on genetic robustness recently revealed transcriptional adaptation (TA) as a mechanism by which an organism can compensate for genetic mutations through activation of homologous genes. Here, we discovered that genetic mutations, introducing a premature termination codon (PTC) in the amyloid precursor protein-b (appb) gene, activated TA of two other app family members, appa and amyloid precursor-like protein-2 (aplp2), in zebrafish. The observed transcriptional response of appa and aplp2 required degradation of mutant mRNA and did not depend on Appb protein level. Furthermore, TA between amyloid precursor protein (APP) family members was observed in human neuronal progenitor cells; however, compensation was only present during early neuronal differentiation and could not be detected in a more differentiated neuronal stage or adult zebrafish brain. Using knockdown and chemical inhibition, we showed that nonsense-mediated mRNA decay (NMD) is involved in degradation of mutant mRNA and that Upf1 and Upf2, key proteins in the NMD pathway, regulate the endogenous transcript levels of appa, appb, aplp1, and aplp2 In conclusion, our results suggest that the expression level of App family members is regulated by the NMD pathway and that mutations destabilizing app/APP mRNA can induce genetic compensation by other family members through TA in both zebrafish and human neuronal progenitors.
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Affiliation(s)
- Maryam Rahmati
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
| | - Jasmine Chebli
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
| | - Rakesh Kumar Banote
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
| | - Sandra Roselli
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
| | - Lotta Agholme
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
- Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London WC1N #BG, United Kingdom
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal 431 41, Sweden
- United Kingdom Dementia Research Institute, London W1T 7NF, United Kingdom
- Hong Kong Center for Neurodegenerative Diseases, 17 Science Park W Ave, Hong Kong, China
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin 53792
| | - Alexandra Abramsson
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg 413 45, Sweden
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3
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Chapman JH, Youle AM, Grimme AL, Neuman K, Hogg J. UPF1 ATPase autoinhibition and activation modulate RNA binding kinetics and NMD efficiency. Nucleic Acids Res 2024; 52:5376-5391. [PMID: 38412299 PMCID: PMC11109973 DOI: 10.1093/nar/gkae136] [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: 11/09/2023] [Revised: 01/31/2024] [Accepted: 02/13/2024] [Indexed: 02/29/2024] Open
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 (i.e. poorly processive, slow, and mechanochemically uncoupled) 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 RNA binding kinetics and enhanced ATP-stimulated RNA 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, MD 20892, USA
| | - Alice M Youle
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Acadia L Grimme
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Keir C Neuman
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - J Robert Hogg
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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4
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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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5
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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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6
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Staszewski J, Lazarewicz N, Konczak J, Migdal I, Maciaszczyk-Dziubinska E. UPF1-From mRNA Degradation to Human Disorders. Cells 2023; 12:cells12030419. [PMID: 36766761 PMCID: PMC9914065 DOI: 10.3390/cells12030419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/07/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
Up-frameshift protein 1 (UPF1) plays the role of a vital controller for transcripts, ready to react in the event of an incorrect translation mechanism. It is well known as one of the key elements involved in mRNA decay pathways and participates in transcript and protein quality control in several different aspects. Firstly, UPF1 specifically degrades premature termination codon (PTC)-containing products in a nonsense-mediated mRNA decay (NMD)-coupled manner. Additionally, UPF1 can potentially act as an E3 ligase and degrade target proteins independently from mRNA decay pathways. Thus, UPF1 protects cells against the accumulation of misfolded polypeptides. However, this multitasking protein may still hide many of its functions and abilities. In this article, we summarize important discoveries in the context of UPF1, its involvement in various cellular pathways, as well as its structural importance and mutational changes related to the emergence of various pathologies and disease states. Even though the state of knowledge about this protein has significantly increased over the years, there are still many intriguing aspects that remain unresolved.
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Affiliation(s)
- Jacek Staszewski
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
- Correspondence: (J.S.); (E.M.-D.)
| | - Natalia Lazarewicz
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
- Institute of Genetics and Development of Rennes, CNRS UMR 6290, University of Rennes 1, 35000 Rennes, France
| | - Julia Konczak
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Iwona Migdal
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Ewa Maciaszczyk-Dziubinska
- Department of Genetics and Cell Physiology, Faculty of Biological Sciences, University of Wroclaw, 50-328 Wroclaw, Poland
- Correspondence: (J.S.); (E.M.-D.)
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7
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Johnson JL, Yaron TM, Huntsman EM, Kerelsky A, Song J, Regev A, Lin TY, Liberatore K, Cizin DM, Cohen BM, Vasan N, Ma Y, Krismer K, Robles JT, van de Kooij B, van Vlimmeren AE, Andrée-Busch N, Käufer NF, Dorovkov MV, Ryazanov AG, Takagi Y, Kastenhuber ER, Goncalves MD, Hopkins BD, Elemento O, Taatjes DJ, Maucuer A, Yamashita A, Degterev A, Uduman M, Lu J, Landry SD, Zhang B, Cossentino I, Linding R, Blenis J, Hornbeck PV, Turk BE, Yaffe MB, Cantley LC. An atlas of substrate specificities for the human serine/threonine kinome. Nature 2023; 613:759-766. [PMID: 36631611 PMCID: PMC9876800 DOI: 10.1038/s41586-022-05575-3] [Citation(s) in RCA: 161] [Impact Index Per Article: 161.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 11/17/2022] [Indexed: 01/13/2023]
Abstract
Protein phosphorylation is one of the most widespread post-translational modifications in biology1,2. With advances in mass-spectrometry-based phosphoproteomics, 90,000 sites of serine and threonine phosphorylation have so far been identified, and several thousand have been associated with human diseases and biological processes3,4. For the vast majority of phosphorylation events, it is not yet known which of the more than 300 protein serine/threonine (Ser/Thr) kinases encoded in the human genome are responsible3. Here we used synthetic peptide libraries to profile the substrate sequence specificity of 303 Ser/Thr kinases, comprising more than 84% of those predicted to be active in humans. Viewed in its entirety, the substrate specificity of the kinome was substantially more diverse than expected and was driven extensively by negative selectivity. We used our kinome-wide dataset to computationally annotate and identify the kinases capable of phosphorylating every reported phosphorylation site in the human Ser/Thr phosphoproteome. For the small minority of phosphosites for which the putative protein kinases involved have been previously reported, our predictions were in excellent agreement. When this approach was applied to examine the signalling response of tissues and cell lines to hormones, growth factors, targeted inhibitors and environmental or genetic perturbations, it revealed unexpected insights into pathway complexity and compensation. Overall, these studies reveal the intrinsic substrate specificity of the human Ser/Thr kinome, illuminate cellular signalling responses and provide a resource to link phosphorylation events to biological pathways.
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Affiliation(s)
- Jared L Johnson
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Tomer M Yaron
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medicine, New York, NY, USA
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- Tri-Institutional PhD Program in Computational Biology & Medicine, Weill Cornell Medicine, Memorial Sloan Kettering Cancer Center and The Rockefeller University, New York, NY, USA
| | - Emily M Huntsman
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Alexander Kerelsky
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medicine, New York, NY, USA
| | - Junho Song
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Amit Regev
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Ting-Yu Lin
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
- Weill Cornell Graduate School of Medical Sciences, Cell and Developmental Biology Program, New York, NY, USA
| | - Katarina Liberatore
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Daniel M Cizin
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Benjamin M Cohen
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Neil Vasan
- Department of Medicine, Division of Hematology/Oncology, Columbia University Irving Medical Center, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Yilun Ma
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Konstantin Krismer
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
- Center for Precision Cancer Medicine, Koch Institute for Integrative Cancer Biology, Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jaylissa Torres Robles
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Bert van de Kooij
- Center for Precision Cancer Medicine, Koch Institute for Integrative Cancer Biology, Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Anne E van Vlimmeren
- Center for Precision Cancer Medicine, Koch Institute for Integrative Cancer Biology, Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nicole Andrée-Busch
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Norbert F Käufer
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Maxim V Dorovkov
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Alexey G Ryazanov
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Yuichiro Takagi
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Edward R Kastenhuber
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Marcus D Goncalves
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Division of Endocrinology, Weill Cornell Medicine, New York, NY, USA
| | - Benjamin D Hopkins
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Olivier Elemento
- Englander Institute for Precision Medicine, Institute for Computational Biomedicine, Weill Cornell Medicine, New York, NY, USA
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
| | - Dylan J Taatjes
- Department of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Alexandre Maucuer
- SABNP, Univ Evry, INSERM U1204, Université Paris-Saclay, Evry, France
| | - Akio Yamashita
- Department of Investigative Medicine, Graduate School of Medicine, University of the Ryukyus, Nishihara-cho, Japan
| | - Alexei Degterev
- Department of Developmental, Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, USA
| | - Mohamed Uduman
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Jingyi Lu
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Sean D Landry
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Bin Zhang
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Ian Cossentino
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Rune Linding
- Rewire Tx, Humboldt-Universität zu Berlin, Berlin, Germany
| | - John Blenis
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA
- Department of Pharmacology, Weill Cornell Medicine, New York, NY, USA
- Department of Biochemistry, Weill Cornell Medicine, New York, NY, USA
| | - Peter V Hornbeck
- Department Of Bioinformatics, Cell Signaling Technology, Danvers, MA, USA
| | - Benjamin E Turk
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA.
| | - Michael B Yaffe
- Center for Precision Cancer Medicine, Koch Institute for Integrative Cancer Biology, Departments of Biology and Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Divisions of Acute Care Surgery, Trauma, and Surgical Critical Care, and Surgical Oncology, Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
- Surgical Oncology Program, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Lewis C Cantley
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA.
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8
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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: 7] [Impact Index Per Article: 3.5] [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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9
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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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10
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Langer LM, Bonneau F, Gat Y, Conti E. Cryo-EM reconstructions of inhibitor-bound SMG1 kinase reveal an autoinhibitory state dependent on SMG8. eLife 2021; 10:72353. [PMID: 34698635 PMCID: PMC8592573 DOI: 10.7554/elife.72353] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/25/2021] [Indexed: 12/31/2022] Open
Abstract
The PI3K-related kinase (PIKK) SMG1 monitors the progression of metazoan nonsense-mediated mRNA decay (NMD) by phosphorylating the RNA helicase UPF1. Previous work has shown that the activity of SMG1 is impaired by small molecule inhibitors, is reduced by the SMG1 interactors SMG8 and SMG9, and is downregulated by the so-called SMG1 insertion domain. However, the molecular basis for this complex regulatory network has remained elusive. Here, we present cryo-electron microscopy reconstructions of human SMG1-9 and SMG1-8-9 complexes bound to either a SMG1 inhibitor or a non-hydrolyzable ATP analog at overall resolutions ranging from 2.8 to 3.6 Å. These structures reveal the basis with which a small molecule inhibitor preferentially targets SMG1 over other PIKKs. By comparison with our previously reported substrate-bound structure (Langer et al.,2020), we show that the SMG1 insertion domain can exert an autoinhibitory function by directly blocking the substrate-binding path as well as overall access to the SMG1 kinase active site. Together with biochemical analysis, our data indicate that SMG1 autoinhibition is stabilized by the presence of SMG8. Our results explain the specific inhibition of SMG1 by an ATP-competitive small molecule, provide insights into regulation of its kinase activity within the NMD pathway, and expand the understanding of PIKK regulatory mechanisms in general.
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Affiliation(s)
- Lukas M Langer
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Fabien Bonneau
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Yair Gat
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elena Conti
- Max Planck Institute of Biochemistry, Martinsried, Germany
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11
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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: 39] [Impact Index Per Article: 13.0] [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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12
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UPF1 promotes chemoresistance to oxaliplatin through regulation of TOP2A activity and maintenance of stemness in colorectal cancer. Cell Death Dis 2021; 12:519. [PMID: 34021129 PMCID: PMC8140095 DOI: 10.1038/s41419-021-03798-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 02/04/2023]
Abstract
UPF1 is proved to dysregulate in multiple tumors and influence carcinogenesis. However, the role of UPF1 in oxaliplatin resistance in colorectal cancer (CRC) remains unknown. In our study, UPF1 is upregulated in CRC in mRNA and protein levels and overexpression of UPF1 predicts a poor overall survival (OS) and recurrence-free survival (RFS) in CRC patients and is an independent risk factor for recurrence. UPF1 promotes chemoresistance to oxaliplatin in vitro and in vivo. UPF1-induced oxaliplatin resistance can be associated with interaction between zinc finger of UPF1 and Toprim of TOP2A and increasing phosphorylated TOP2A in a SMG1-dependent manner. Moreover, UPF1 maintains stemness in a TOP2A-dependent manner in CRC. Taken together, UPF1 was overexpressed and predicted a poor prognosis in CRC. UPF1 enhanced chemoresistance to oxaliplatin in CRC, which may result from regulation of TOP2A activity and maintenance of stemness. Our findings could provide a new therapy strategy for chemoresistance to oxaliplatin in CRC patients.
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13
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Nogueira G, Fernandes R, García-Moreno JF, Romão L. Nonsense-mediated RNA decay and its bipolar function in cancer. Mol Cancer 2021; 20:72. [PMID: 33926465 PMCID: PMC8082775 DOI: 10.1186/s12943-021-01364-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 04/19/2021] [Indexed: 12/17/2022] Open
Abstract
Nonsense-mediated decay (NMD) was first described as a quality-control mechanism that targets and rapidly degrades aberrant mRNAs carrying premature termination codons (PTCs). However, it was found that NMD also degrades a significant number of normal transcripts, thus arising as a mechanism of gene expression regulation. Based on these important functions, NMD regulates several biological processes and is involved in the pathophysiology of a plethora of human genetic diseases, including cancer. The present review aims to discuss the paradoxical, pro- and anti-tumorigenic roles of NMD, and how cancer cells have exploited both functions to potentiate the disease. Considering recent genetic and bioinformatic studies, we also provide a comprehensive overview of the present knowledge of the advantages and disadvantages of different NMD modulation-based approaches in cancer therapy, reflecting on the challenges imposed by the complexity of this disease. Furthermore, we discuss significant advances in the recent years providing new perspectives on the implications of aberrant NMD-escaping frameshifted transcripts in personalized immunotherapy design and predictive biomarker optimization. A better understanding of how NMD differentially impacts tumor cells according to their own genetic identity will certainly allow for the application of novel and more effective personalized treatments in the near future.
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Affiliation(s)
- Gonçalo Nogueira
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Rafael Fernandes
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Juan F García-Moreno
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal.,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal
| | - Luísa Romão
- Departamento de Genética Humana, Instituto Nacional de Saúde Doutor Ricardo Jorge, 1649-016, Lisbon, Portugal. .,BioISI - Instituto de Biossistemas e Ciências Integrativas, Faculdade de Ciências, Universidade de Lisboa, 1749-016, Lisbon, Portugal.
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14
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Ghiasi SM, Rutter GA. Consequences for Pancreatic β-Cell Identity and Function of Unregulated Transcript Processing. Front Endocrinol (Lausanne) 2021; 12:625235. [PMID: 33763030 PMCID: PMC7984428 DOI: 10.3389/fendo.2021.625235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/26/2021] [Indexed: 12/25/2022] Open
Abstract
Mounting evidence suggests a role for alternative splicing (AS) of transcripts in the normal physiology and pathophysiology of the pancreatic β-cell. In the apparent absence of RNA repair systems, RNA decay pathways are likely to play an important role in controlling the stability, distribution and diversity of transcript isoforms in these cells. Around 35% of alternatively spliced transcripts in human cells contain premature termination codons (PTCs) and are targeted for degradation via nonsense-mediated decay (NMD), a vital quality control process. Inflammatory cytokines, whose levels are increased in both type 1 (T1D) and type 2 (T2D) diabetes, stimulate alternative splicing events and the expression of NMD components, and may or may not be associated with the activation of the NMD pathway. It is, however, now possible to infer that NMD plays a crucial role in regulating transcript processing in normal and stress conditions in pancreatic β-cells. In this review, we describe the possible role of Regulated Unproductive Splicing and Translation (RUST), a molecular mechanism embracing NMD activity in relationship to AS and translation of damaged transcript isoforms in these cells. This process substantially reduces the abundance of non-functional transcript isoforms, and its dysregulation may be involved in pancreatic β-cell failure in diabetes.
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Affiliation(s)
- Seyed M. Ghiasi
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Guy A. Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, United Kingdom
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15
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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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16
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López-Perrote A, Hug N, González-Corpas A, Rodríguez CF, Serna M, García-Martín C, Boskovic J, Fernandez-Leiro R, Caceres JF, Llorca O. Regulation of RUVBL1-RUVBL2 AAA-ATPases by the nonsense-mediated mRNA decay factor DHX34, as evidenced by Cryo-EM. eLife 2020; 9:63042. [PMID: 33205750 PMCID: PMC7707835 DOI: 10.7554/elife.63042] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 11/12/2020] [Indexed: 11/13/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a surveillance pathway that degrades aberrant mRNAs and also regulates the expression of a wide range of physiological transcripts. RUVBL1 and RUVBL2 AAA-ATPases form an hetero-hexameric ring that is part of several macromolecular complexes such as INO80, SWR1, and R2TP. Interestingly, RUVBL1-RUVBL2 ATPase activity is required for NMD activation by an unknown mechanism. Here, we show that DHX34, an RNA helicase regulating NMD initiation, directly interacts with RUVBL1-RUVBL2 in vitro and in cells. Cryo-EM reveals that DHX34 induces extensive changes in the N-termini of every RUVBL2 subunit in the complex, stabilizing a conformation that does not bind nucleotide and thereby down-regulates ATP hydrolysis of the complex. Using ATPase-deficient mutants, we find that DHX34 acts exclusively on the RUVBL2 subunits. We propose a model, where DHX34 acts to couple RUVBL1-RUVBL2 ATPase activity to the assembly of factors required to initiate the NMD response.
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Affiliation(s)
- Andres López-Perrote
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Nele Hug
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburghx, Edinburgh, United Kingdom
| | - Ana González-Corpas
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Carlos F Rodríguez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Marina Serna
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Carmen García-Martín
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Jasminka Boskovic
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Rafael Fernandez-Leiro
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Javier F Caceres
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburghx, Edinburgh, United Kingdom
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
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17
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Deka B, Chandra P, Singh KK. Functional roles of human Up-frameshift suppressor 3 (UPF3) proteins: From nonsense-mediated mRNA decay to neurodevelopmental disorders. Biochimie 2020; 180:10-22. [PMID: 33132159 DOI: 10.1016/j.biochi.2020.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 10/03/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is a post-transcriptional quality control mechanism that eradicates aberrant transcripts from cells. Aberrant transcripts are recognized by translating ribosomes, eRFs, and trans-acting NMD factors leading to their degradation. The trans-factors are conserved among eukaryotes and consist of UPF1, UPF2, and UPF3 proteins. Intriguingly, in humans, UPF3 exists as paralog proteins, UPF3A, and UPF3B. While UPF3 paralogs are traditionally known to be involved in the NMD pathway, there is a growing consensus that there are other critical cellular functions beyond quality control that are dictated by the UPF3 proteins. This review presents the current knowledge on the biochemical functions of UPF3 paralogs in diverse cellular processes, including NMD, translation, and genetic compensation response. We also discuss the contribution of the UPF3 paralogs in development and function of the central nervous system and germ cells. Furthermore, significant advances in the past decade have provided new perspectives on the implications of UPF3 paralogs in neurodevelopmental diseases. In this regard, genome- and transcriptome-wide sequencing analysis of patient samples revealed that loss of UPF3B is associated with brain disorders such as intellectual disability, autism, attention deficit hyperactivity disorder, and schizophrenia. Therefore, we further aim to provide an insight into the brain diseases associated with loss-of-function mutations of UPF3B.
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Affiliation(s)
- Bhagyashree Deka
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Pratap Chandra
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
| | - Kusum Kumari Singh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
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18
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The human papillomavirus E6 protein targets apoptosis-inducing factor (AIF) for degradation. Sci Rep 2020; 10:14195. [PMID: 32848167 PMCID: PMC7450093 DOI: 10.1038/s41598-020-71134-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 08/07/2020] [Indexed: 12/13/2022] Open
Abstract
Oncoprotein E6 of high-risk human papillomavirus (HPV) plays a critical role in inducing cell immortalization and malignancy. E6 downregulates caspase-dependent pathway through the degradation of p53. However, the effect of HPV E6 on other pathways is still under investigation. In the present study, we found that HPV E6 directly binds to all three forms (precursor, mature, and apoptotic) of apoptosis-inducing factor (AIF) and co-localizes with apoptotic AIF. This binding induced MG132-sensitive reduction of AIF expression in the presence of E6 derived from HPV16 (16E6), a cancer-causing type of HPV. Conversely, E6 derived from a non-cancer-causing type of HPV, HPV6 (6E6), did not reduce the levels of AIF despite its interaction with AIF. Flow cytometric analysis revealed that 16E6, but not 6E6, suppressed apoptotic AIF-induced chromatin degradation (an indicator of caspase-independent apoptosis) and staurosporine (STS, a protein kinase inhibitor)-induced apoptosis. AIF knockdown reduced STS-induced apoptosis in both of 16E6-expressing and 6E6-expressing cells; however, the reduction in 16E6-expressing cells was lower than that in 6E6-expressing cells. These findings indicate that 16E6, but not 6E6, blocks AIF-mediated apoptosis, and that AIF may represent a novel therapeutic target for HPV-induced cervical cancer.
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Powers KT, Szeto JYA, Schaffitzel C. New insights into no-go, non-stop and nonsense-mediated mRNA decay complexes. Curr Opin Struct Biol 2020; 65:110-118. [PMID: 32688260 DOI: 10.1016/j.sbi.2020.06.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 06/10/2020] [Accepted: 06/18/2020] [Indexed: 11/26/2022]
Abstract
Eukaryotes possess a variety of translational control mechanisms which function in the surveillance of mRNAs, discriminating between normal and aberrant translation elongation and termination, triggering mRNA decay. The three major evolutionarily conserved eukaryotic pathways are No-Go, Non-Stop and Nonsense-Mediated mRNA Decay. Recent findings suggest that stalling of the ribosome, due to mRNA secondary structure or translation into poly(A)-stretches, leads to ribosome collisions which are detected by No-Go/Non-Stop mRNA decay factors. Subsequent ribosome ubiquitination at the interface of two collided ribosomes is considered the signal for mRNA decay. Similarly, translation termination at a premature stop codon is slower than normal, leading to recruitment and activation of nonsense-mediated mRNA decay factors, including SMG1-8-9. Here, we detail new insights into the molecular mechanisms of these pathways.
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Affiliation(s)
- Kyle T Powers
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom
| | - Jenn-Yeu Alvin Szeto
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom
| | - Christiane Schaffitzel
- University of Bristol, School of Biochemistry, University Walk, Bristol, BS8 1TD, United Kingdom.
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Lavysh D, Neu-Yilik G. UPF1-Mediated RNA Decay-Danse Macabre in a Cloud. Biomolecules 2020; 10:E999. [PMID: 32635561 PMCID: PMC7407380 DOI: 10.3390/biom10070999] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 12/21/2022] Open
Abstract
Nonsense-mediated RNA decay (NMD) is the prototype example of a whole family of RNA decay pathways that unfold around a common central effector protein called UPF1. While NMD in yeast appears to be a linear pathway, NMD in higher eukaryotes is a multifaceted phenomenon with high variability with respect to substrate RNAs, degradation efficiency, effector proteins and decay-triggering RNA features. Despite increasing knowledge of the mechanistic details, it seems ever more difficult to define NMD and to clearly distinguish it from a growing list of other UPF1-mediated RNA decay pathways (UMDs). With a focus on mammalian, we here critically examine the prevailing NMD models and the gaps and inconsistencies in these models. By exploring the minimal requirements for NMD and other UMDs, we try to elucidate whether they are separate and definable pathways, or rather variations of the same phenomenon. Finally, we suggest that the operating principle of the UPF1-mediated decay family could be considered similar to that of a computing cloud providing a flexible infrastructure with rapid elasticity and dynamic access according to specific user needs.
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Affiliation(s)
- Daria Lavysh
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany;
- Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Im Neuenheimer Feld 350, 69120 Heidelberg, Germany
- Department Clinical Pediatric Oncology, Hopp Kindertumorzentrum am NCT Heidelberg, 69120 Heidelberg, Germany
| | - Gabriele Neu-Yilik
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany;
- Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Im Neuenheimer Feld 350, 69120 Heidelberg, Germany
- Department Clinical Pediatric Oncology, Hopp Kindertumorzentrum am NCT Heidelberg, 69120 Heidelberg, Germany
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Pervasive changes of mRNA splicing in upf1-deficient zebrafish identify rpl10a as a regulator of T cell development. Proc Natl Acad Sci U S A 2020; 117:15799-15808. [PMID: 32571908 PMCID: PMC7354994 DOI: 10.1073/pnas.1917812117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transcriptome of eukaryotic cells is constantly monitored for errors to avoid the production of undesired protein variants. The evolutionarily conserved nonsense-mediated mRNA decay (NMD) pathway degrades aberrant mRNAs, but also functions in the regulation of transcript abundance in response to changed physiological states. Here, we describe a zebrafish mutant of upf1, encoding the central component of the NMD machinery. Fish homozygous for the upf1 t20450 allele (Y163X) survive until day 10 after fertilization, presenting with impaired T cell development as one of the most conspicuous features of the mutant phenotype. Analysis of differentially expressed genes identified dysregulation of the pre-mRNA splicing pathway, accompanied by perturbed autoregulation of canonical splicing activators (SRSF) and repressors (HNRNP). In upf1-deficient mutants, NMD-susceptible transcripts of ribosomal proteins that are known for their role as noncanonical splicing regulators were greatly increased, most notably, rpl10a When the levels of NMD-susceptible rpl10a transcripts were artificially increased in zebrafish larvae, T cell development was significantly impaired, suggesting that perturbed autoregulation of rpl10a splicing contributes to failing T cell development in upf1 deficiency. Our results identify an extraribosomal tissue-specific function to rpl10a in the immune system, and thus exemplify the advantages of the zebrafish model to study the effects of upf1-deficiency in the context of a vertebrate organism.
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22
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The Complex Relationship between HTLV-1 and Nonsense-Mediated mRNA Decay (NMD). Pathogens 2020; 9:pathogens9040287. [PMID: 32326562 PMCID: PMC7238105 DOI: 10.3390/pathogens9040287] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/09/2020] [Accepted: 04/12/2020] [Indexed: 02/07/2023] Open
Abstract
Before the establishment of an adaptive immune response, retroviruses can be targeted by several cellular host factors at different stages of the viral replication cycle. This intrinsic immunity relies on a large diversity of antiviral processes. In the case of HTLV-1 infection, these active innate host defense mechanisms are debated. Among these mechanisms, we focused on an RNA decay pathway called nonsense-mediated mRNA decay (NMD), which can target multiple viral RNAs, including HTLV-1 unspliced RNA, as has been recently demonstrated. NMD is a co-translational process that depends on the RNA helicase UPF1 and regulates the expression of multiple types of host mRNAs. RNA sensitivity to NMD depends on mRNA organization and the ribonucleoprotein (mRNP) composition. HTLV-1 has evolved several means to evade the NMD threat, leading to NMD inhibition. In the early steps of infection, NMD inhibition favours the production of HTLV-1 infectious particles, which may contribute to the survival of the fittest clones despite genome instability; however, its direct long-term impact remains to be investigated.
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Shank2 Binds to aPKC and Controls Tight Junction Formation with Rap1 Signaling during Establishment of Epithelial Cell Polarity. Cell Rep 2020; 31:107407. [DOI: 10.1016/j.celrep.2020.02.088] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/22/2020] [Accepted: 02/25/2020] [Indexed: 11/19/2022] Open
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Mechanisms and Regulation of Nonsense-Mediated mRNA Decay and Nonsense-Associated Altered Splicing in Lymphocytes. Int J Mol Sci 2020; 21:ijms21041335. [PMID: 32079193 PMCID: PMC7072976 DOI: 10.3390/ijms21041335] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 12/11/2022] Open
Abstract
The presence of premature termination codons (PTCs) in transcripts is dangerous for the cell as they encode potentially deleterious truncated proteins that can act with dominant-negative or gain-of-function effects. To avoid the synthesis of these shortened polypeptides, several RNA surveillance systems can be activated to decrease the level of PTC-containing mRNAs. Nonsense-mediated mRNA decay (NMD) ensures an accelerated degradation of mRNAs harboring PTCs by using several key NMD factors such as up-frameshift (UPF) proteins. Another pathway called nonsense-associated altered splicing (NAS) upregulates transcripts that have skipped disturbing PTCs by alternative splicing. Thus, these RNA quality control processes eliminate abnormal PTC-containing mRNAs from the cells by using positive and negative responses. In this review, we describe the general mechanisms of NMD and NAS and their respective involvement in the decay of aberrant immunoglobulin and TCR transcripts in lymphocytes.
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Jojima K, Edagawa M, Sawai M, Ohno Y, Kihara A. Biosynthesis of the anti-lipid-microdomain sphingoid base 4,14-sphingadiene by the ceramide desaturase FADS3. FASEB J 2020; 34:3318-3335. [PMID: 31916624 DOI: 10.1096/fj.201902645r] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 12/23/2019] [Accepted: 12/24/2019] [Indexed: 11/11/2022]
Abstract
Sphingolipids are multifunctional lipids. Among the sphingolipid-component sphingoid bases, 4,14-sphingadiene (SPD) is unique such that it has a cis double bond with a bent structure. Although SPD was discovered half a century ago, its tissue distribution, biosynthesis, and degradation remain poorly understood. Here, we established a specific and quantitative method for SPD measurement and found that SPD exists in a wide range of mammalian tissues. SPD was especially abundant in kidney, where the amount of SPD was ~2/3 of sphingosine, the most abundant sphingoid base in mammals. Although SPD is metabolized to ceramides and SPD 1-phosphate with almost the same efficiency as sphingosine, it is less susceptible to degradation by a cleavage reaction, at least in vitro. We identified the fatty acid desaturase family protein FADS3 as a ceramide desaturase that produces SPD ceramides by desaturating ceramides containing sphingosine. SPD sphingolipids were preferentially localized outside lipid microdomains, suggesting that SPD has different functions compared to other sphingoid bases in the formation of lipid microdomains. In summary, we revealed the biosynthesis and degradation pathways of SPD and its characteristic membrane localization. Our findings contribute to the elucidation of the molecular mechanism underlying the generation of sphingolipid diversity.
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Affiliation(s)
- Keisuke Jojima
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Mai Edagawa
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Megumi Sawai
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Yusuke Ohno
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
| | - Akio Kihara
- Laboratory of Biochemistry, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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26
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Wu Y, Zhou L, Wang Z, Wang X, Zhang R, Zheng L, Kang T. Systematic screening for potential therapeutic targets in osteosarcoma through a kinome-wide CRISPR-Cas9 library. Cancer Biol Med 2020; 17:782-794. [PMID: 32944406 PMCID: PMC7476084 DOI: 10.20892/j.issn.2095-3941.2020.0162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Objective: Osteosarcoma is the most common primary malignant bone tumor. However, the survival of patients with osteosarcoma has remained unchanged during the past 30 years, owing to a lack of efficient therapeutic targets. Methods: We constructed a kinome-targeting CRISPR-Cas9 library containing 507 kinases and 100 nontargeting controls and screened the potential kinase targets in osteosarcoma. The CRISPR screening sequencing data were analyzed with the Model-based Analysis of Genome-wide CRISPR/Cas9 Knockout (MAGeCK) Python package. The functional data were applied in the 143B cell line through lenti-CRISPR-mediated gene knockout. The clinical significance of kinases in the survival of patients with osteosarcoma was analyzed in the R2: Genomics Analysis and Visualization Platform. Results: We identified 53 potential kinase targets in osteosarcoma. Among these targets, we analyzed 3 kinases, TRRAP, PKMYT1, and TP53RK, to validate their oncogenic functions in osteosarcoma. PKMYT1 and TP53RK showed higher expression in osteosarcoma than in normal bone tissue, whereas TRRAP showed no significant difference. High expression of all 3 kinases was associated with relatively poor prognosis in patients with osteosarcoma. Conclusions: Our results not only offer potential therapeutic kinase targets in osteosarcoma but also provide a paradigm for functional genetic screening by using a CRISPR-Cas9 library, including target design, library construction, screening workflow, data analysis, and functional validation. This method may also be useful in potentially accelerating drug discovery for other cancer types.
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Affiliation(s)
- Yuanzhong Wu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Liwen Zhou
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Zifeng Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Xin Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Ruhua Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Lisi Zheng
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
| | - Tiebang Kang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, China
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27
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InsP6 binding to PIKK kinases revealed by the cryo-EM structure of an SMG1–SMG8–SMG9 complex. Nat Struct Mol Biol 2019; 26:1089-1093. [DOI: 10.1038/s41594-019-0342-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 10/28/2019] [Indexed: 12/30/2022]
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28
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New insights into the evolutionary conservation of the sole PIKK pseudokinase Tra1/TRRAP. Biochem Soc Trans 2019; 47:1597-1608. [DOI: 10.1042/bst20180496] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/25/2019] [Accepted: 11/05/2019] [Indexed: 02/07/2023]
Abstract
Phosphorylation by protein kinases is a fundamental mechanism of signal transduction. Many kinase families contain one or several members that, although evolutionarily conserved, lack the residues required for catalytic activity. Studies combining structural, biochemical, and functional approaches revealed that these pseudokinases have crucial roles in vivo and may even represent attractive targets for pharmacological intervention. Pseudokinases mediate signal transduction by a diversity of mechanisms, including allosteric regulation of their active counterparts, assembly of signaling hubs, or modulation of protein localization. One such pseudokinase, named Tra1 in yeast and transformation/transcription domain-associated protein (TRRAP) in mammals, is the only member lacking all catalytic residues within the phosphatidylinositol 3-kinase related kinase (PIKK) family of kinases. PIKKs are related to the PI3K family of lipid kinases, but function as Serine/Threonine protein kinases and have pivotal roles in diverse processes such as DNA damage sensing and repair, metabolic control of cell growth, nonsense-mediated decay, or transcription initiation. Tra1/TRRAP is the largest subunit of two distinct transcriptional co-activator complexes, SAGA and NuA4/TIP60, which it recruits to promoters upon transcription factor binding. Here, we review our current knowledge on the Tra1/TRRAP pseudokinase, focusing on its role as a scaffold for SAGA and NuA4/TIP60 complex assembly and recruitment to chromatin. We further discuss its evolutionary history within the PIKK family and highlight recent findings that reveal the importance of molecular chaperones in pseudokinase folding, function, and conservation.
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29
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Zhu L, Li L, Qi Y, Yu Z, Xu Y. Cryo-EM structure of SMG1-SMG8-SMG9 complex. Cell Res 2019; 29:1027-1034. [PMID: 31729466 DOI: 10.1038/s41422-019-0255-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 10/25/2019] [Indexed: 11/09/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) targets premature stop codon (PTC)-containing mRNAs for rapid degradation, and is essential for mammalian embryonic development, brain development and modulation of the stress response. The key event in NMD is the SMG1-mediated phosphorylation of an RNA helicase UPF1 and SMG1 kinase activity is inhibited by SMG8 and SMG9 in an unknown mechanism. Here, we determined the cryo-EM structures of human SMG1 at 3.6 Å resolution and the SMG1-SMG8-SMG9 complex at 3.4 Å resolution, respectively. SMG8 has a C-terminal kinase inhibitory domain (KID), which covers the catalytic pocket and inhibits the kinase activity of SMG1. Structural analyses suggest that GTP hydrolysis of SMG9 would lead to a dramatic conformational change of SMG8-SMG9 and the KID would move away from the inhibitory position to restore SMG1 kinase activity. Thus, our structural and biochemical analyses provide a mechanistic understanding of SMG1-SMG8-SMG9 complex assembly and the regulatory mechanism of SMG1 kinase activity.
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Affiliation(s)
- Li Zhu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Key Laboratory of Medical Epigenetics and Metabolism, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Liang Li
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Key Laboratory of Medical Epigenetics and Metabolism, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Yilun Qi
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Key Laboratory of Medical Epigenetics and Metabolism, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Zishuo Yu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Key Laboratory of Medical Epigenetics and Metabolism, Shanghai Medical College of Fudan University, Shanghai, 200032, China
| | - Yanhui Xu
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Key Laboratory of Medical Epigenetics and Metabolism, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,Key Laboratory of Molecular Medicine, Ministry of Education, Department of Systems Biology for Medicine, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Shanghai, 200032, China. .,Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai, 200433, China. .,CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031, China.
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30
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Wong C, Chen F, Alirezaie N, Wang Y, Cuggia A, Borgida A, Holter S, Lenko T, Domecq C, Petersen GM, Syngal S, Brand R, Rustgi AK, Cote ML, Stoffel E, Olson SH, Roberts NJ, Akbari MR, Majewski J, Klein AP, Greenwood CMT, Gallinger S, Zogopoulos G. A region-based gene association study combined with a leave-one-out sensitivity analysis identifies SMG1 as a pancreatic cancer susceptibility gene. PLoS Genet 2019; 15:e1008344. [PMID: 31469826 PMCID: PMC6742418 DOI: 10.1371/journal.pgen.1008344] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 09/12/2019] [Accepted: 08/03/2019] [Indexed: 12/18/2022] Open
Abstract
Pancreatic adenocarcinoma (PC) is a lethal malignancy that is familial or associated with genetic syndromes in 10% of cases. Gene-based surveillance strategies for at-risk individuals may improve clinical outcomes. However, familial PC (FPC) is plagued by genetic heterogeneity and the genetic basis for the majority of FPC remains elusive, hampering the development of gene-based surveillance programs. The study was powered to identify genes with a cumulative pathogenic variant prevalence of at least 3%, which includes the most prevalent PC susceptibility gene, BRCA2. Since the majority of known PC susceptibility genes are involved in DNA repair, we focused on genes implicated in these pathways. We performed a region-based association study using the Mixed-Effects Score Test, followed by leave-one-out characterization of PC-associated gene regions and variants to identify the genes and variants driving risk associations. We evaluated 398 cases from two case series and 987 controls without a personal history of cancer. The first case series consisted of 109 patients with either FPC (n = 101) or PC at ≤50 years of age (n = 8). The second case series was composed of 289 unselected PC cases. We validated this discovery strategy by identifying known pathogenic BRCA2 variants, and also identified SMG1, encoding a serine/threonine protein kinase, to be significantly associated with PC following correction for multiple testing (p = 3.22x10-7). The SMG1 association was validated in a second independent series of 532 FPC cases and 753 controls (p<0.0062, OR = 1.88, 95%CI 1.17-3.03). We showed segregation of the c.4249A>G SMG1 variant in 3 affected relatives in a FPC kindred, and we found c.103G>A to be a recurrent SMG1 variant associating with PC in both the discovery and validation series. These results suggest that SMG1 is a novel PC susceptibility gene, and we identified specific SMG1 gene variants associated with PC risk.
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Affiliation(s)
- Cavin Wong
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Fei Chen
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Najmeh Alirezaie
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Yifan Wang
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Adeline Cuggia
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Ayelet Borgida
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Spring Holter
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Tatiana Lenko
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | - Celine Domecq
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
| | | | - Gloria M. Petersen
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Sapna Syngal
- Division of Cancer Genetics and Prevention, Dana-Farber Cancer Institute, Gastroenterology Division, Brigham and Women’s Hospital, Harvard Medical Schozol, Boston, Massachusetts, United States of America
| | - Randall Brand
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Anil K. Rustgi
- Division of Gastroenterology, Departments of Medicine and Genetics, Pancreatic Cancer Translation Center of Excellence, Abramson Cancer Center, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Michele L. Cote
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Elena Stoffel
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Sara H. Olson
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York, United States of America
| | - Nicholas J. Roberts
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland, United States of America
- The Sol Goldman Pancreatic Cancer Research Center, Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mohammad R. Akbari
- Women’s College Hospital Research Institute, Women's College Hospital, Toronto, Ontario, Canada
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - Jacek Majewski
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, Canada
| | - Alison P. Klein
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland, United States of America
- The Sol Goldman Pancreatic Cancer Research Center, Department of Pathology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Celia M. T. Greenwood
- Ludmer Centre for Neuroinformatics & Mental Health, McGill University, Montreal, Quebec, Canada
- Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada
- Gerald Bronfman Department of Oncology, and Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada
| | - Steven Gallinger
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - George Zogopoulos
- The Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
- The Goodman Cancer Research Centre of McGill University, Montreal, Quebec, Canada
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31
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Liao HQ, Liu H, Sun HL, Xiang JB, Wang XX, Jiang CX, Ma L, Cao ZG. MiR-361-3p/ Nfat5 Signaling Axis Controls Cementoblast Differentiation. J Dent Res 2019; 98:1131-1139. [PMID: 31343932 DOI: 10.1177/0022034519864519] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The development of periodontal tissue is a complex process, including cementoblast proliferation and differentiation. Emerging reports suggest that microRNAs (miRNAs) play crucial roles in gene regulatory networks governing numerous biological processes. However, how miRNAs modulate cementoblast proliferation and differentiation remains largely unknown. In a previous study, we performed miRNA microarray profiling to fully reveal the expression patterns of miRNAs involved in cementoblast differentiation. We focused on miR-361-3p, which decreased during cementoblast differentiation. Overexpression of miR-361-3p resulted in decreased cementoblast differentiation, whereas the functional inhibition of miR-361-3p yielded the opposite effect. The bioinformatics approach identified nuclear factor of activated T-cell 5 (Nfat5) as a potential target of miR-361-3p, which was further verified by dual luciferase assay. Meanwhile, the expression pattern of Nfat5 was verified both in vitro and in vivo. Furthermore, knockdown of Nfat5 mimicked the inhibitory effect of overexpressing miR-361-3p in cementoblasts. Moreover, multiple signaling pathways, including the Erk1/2, JNK, p38, PI3K-Akt, and NF-κB pathways, were notably activated, and the Wnt/ß-catenin pathway was blocked by downregulation of Nfat5 or forced expression of miR-361-3p in cementoblast differentiation. Finally, the complementary approach demonstrated that miR-361-3p regulated cementoblast differentiation via or partially via Erk1/2 and PI3K-Akt. Overall, our study elucidated that the JNK, p38, NF-κB, and Wnt/ß-catenin pathways act as balancing players in the miR-361-3p/Nfat5 signaling axis during cementoblast differentiation.
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Affiliation(s)
- H Q Liao
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - H Liu
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China.,2 Department of Periodontology, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - H L Sun
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China.,2 Department of Periodontology, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - J B Xiang
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China.,2 Department of Periodontology, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - X X Wang
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - C X Jiang
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - L Ma
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Z G Cao
- 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST KLOS) and Key Laboratory for Oral Biomedical Engineering of Ministry of Education (KLOBME), School and Hospital of Stomatology, Wuhan University, Wuhan, China.,2 Department of Periodontology, School and Hospital of Stomatology, Wuhan University, Wuhan, China
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32
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Asano K, Suzuki T, Saito A, Wei FY, Ikeuchi Y, Numata T, Tanaka R, Yamane Y, Yamamoto T, Goto T, Kishita Y, Murayama K, Ohtake A, Okazaki Y, Tomizawa K, Sakaguchi Y, Suzuki T. Metabolic and chemical regulation of tRNA modification associated with taurine deficiency and human disease. Nucleic Acids Res 2019; 46:1565-1583. [PMID: 29390138 PMCID: PMC5829720 DOI: 10.1093/nar/gky068] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 01/23/2018] [Indexed: 12/21/2022] Open
Abstract
Modified uridine containing taurine, 5-taurinomethyluridine (τm5U), is found at the anticodon first position of mitochondrial (mt-)transfer RNAs (tRNAs). Previously, we reported that τm5U is absent in mt-tRNAs with pathogenic mutations associated with mitochondrial diseases. However, biogenesis and physiological role of τm5U remained elusive. Here, we elucidated τm5U biogenesis by confirming that 5,10-methylene-tetrahydrofolate and taurine are metabolic substrates for τm5U formation catalyzed by MTO1 and GTPBP3. GTPBP3-knockout cells exhibited respiratory defects and reduced mitochondrial translation. Very little τm5U34 was detected in patient's cells with the GTPBP3 mutation, demonstrating that lack of τm5U results in pathological consequences. Taurine starvation resulted in downregulation of τm5U frequency in cultured cells and animal tissues (cat liver and flatfish). Strikingly, 5-carboxymethylaminomethyluridine (cmnm5U), in which the taurine moiety of τm5U is replaced with glycine, was detected in mt-tRNAs from taurine-depleted cells. These results indicate that tRNA modifications are dynamically regulated via sensing of intracellular metabolites under physiological condition.
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Affiliation(s)
- Kana Asano
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takeo Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Ayaka Saito
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Fan-Yan Wei
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yoshiho Ikeuchi
- Institute of Industrial Science, University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
| | - Tomoyuki Numata
- Biological Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8566, Japan
| | - Ryou Tanaka
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Animal Medical Center, Fuchu, Tokyo 183-8509, Japan
| | - Yoshihisa Yamane
- Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Animal Medical Center, Fuchu, Tokyo 183-8509, Japan
| | - Takeshi Yamamoto
- Tamaki Laboratory, National Research Institute of Aquaculture, Japan Fisheries Research and Education Agency, Tamaki, Mie 519-0423, Japan
| | - Takanobu Goto
- Department of Chemistry & Biochemistry, National Institute of Technology, Numazu College, Numazu, Shizuoka 410-8501, Japan
| | - Yoshihito Kishita
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Midori-ku, Chiba 266-0007, Japan
| | - Akira Ohtake
- Department of Pediatrics, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350-0495, Japan
| | - Yasushi Okazaki
- Division of Functional Genomics & Systems Medicine, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan.,Division of Translational Research, Research Center for Genomic Medicine, Saitama Medical University, Hidaka, Saitama 350-1240, Japan
| | - Kazuhito Tomizawa
- Department of Molecular Physiology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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33
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Tan Y, Ma Z, Jin Y, Zong R, Wu J, Ren Z. MicroRNA 4651 regulates nonsense-mediated mRNA decay by targeting SMG9 mRNA. Gene 2019; 701:65-71. [PMID: 30902786 DOI: 10.1016/j.gene.2019.03.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 03/11/2019] [Accepted: 03/17/2019] [Indexed: 02/07/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is originally identified as a conserved RNA surveillance mechanism that rapidly degrades aberrant mRNA containing premature termination codons (PTCs). However, the molecular regulation mechanisms by which microRNAs inhibit NMD has not been well understood. Here we identified that miR-4651 participated in the NMD pathway by downregulating expression levels of SMG9. We provided evidences that (1) Overexpression of miR-4651 mimic significantly inhibited the expression of SMG9 (P < 0.05); (2) NMD substrates genes, TBL2 and GADD45B were both increased at mRNA and protein expression levels when SMG9 was suppressed by siRNA, whereas decreased by SMG9 overexpression; (3) Expression of SMG9 was significantly increased but TBL2, GADD45B were significantly decreased when cells transfected with miR-4651 inhibitor (P < 0.05). These results indicated that miR-4651 regulated NMD by targeting SMG9 mRNA. Our study highlights that miR-4651 represses NMD. miR-4651 targets SMG9 and represses the expression levels of SMG9. NMD activity is decreased additionally when SMG9 is inhibited. The present study provides evidence for microRNA/NMD regulatory mechanism.
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Affiliation(s)
- Yanjie Tan
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Zhenfa Ma
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Ruojun Zong
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Jian Wu
- College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
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Rao S, Amorim R, Niu M, Breton Y, Tremblay MJ, Mouland AJ. Host mRNA decay proteins influence HIV-1 replication and viral gene expression in primary monocyte-derived macrophages. Retrovirology 2019; 16:3. [PMID: 30732620 PMCID: PMC6367771 DOI: 10.1186/s12977-019-0465-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 01/29/2019] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Mammalian cells harbour RNA quality control and degradative machineries such as nonsense-mediated mRNA decay that target cellular mRNAs for clearance from the cell to avoid aberrant gene expression. The role of the host mRNA decay pathways in macrophages in the context of human immunodeficiency virus type 1 (HIV-1) infection is yet to be elucidated. Macrophages are directly infected by HIV-1, mediate the dissemination of the virus and contribute to the chronic activation of the inflammatory response observed in infected individuals. Therefore, we characterized the effects of four host mRNA decay proteins, i.e., UPF1, UPF2, SMG6 and Staufen1, on viral replication in HIV-1-infected primary monocyte-derived macrophages (MDMs). RESULTS Steady-state expression levels of these host mRNA decay proteins were significantly downregulated in HIV-1-infected MDMs. Moreover, UPF2 and SMG6 inhibited HIV-1 gene expression in macrophages to a similar level achieved by SAMHD1, by directly influencing viral genomic RNA levels. Staufen1, a host protein also involved in UPF1-dependent mRNA decay and that acts at several HIV-1 replication steps, enhanced HIV-1 gene expression in MDMs. CONCLUSIONS These results provide new evidence for roles of host mRNA decay proteins in regulating HIV-1 replication in infected macrophages and can serve as potential targets for broad-spectrum antiviral therapeutics.
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Affiliation(s)
- Shringar Rao
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec, Canada.,Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Raquel Amorim
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec, Canada.,Department of Medicine, McGill University, Montréal, Québec, Canada
| | - Meijuan Niu
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec, Canada
| | - Yann Breton
- Axe des Maladies Infectieuses et Immunitaires, Centre de Recherche du CHU de Québec-Université Laval, Québec, Québec, Canada
| | - Michel J Tremblay
- Axe des Maladies Infectieuses et Immunitaires, Centre de Recherche du CHU de Québec-Université Laval, Québec, Québec, Canada.,Département de Microbiologie-Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec, Canada. .,Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada. .,Department of Medicine, McGill University, Montréal, Québec, Canada.
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35
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Karousis ED, Mühlemann O. Nonsense-Mediated mRNA Decay Begins Where Translation Ends. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032862. [PMID: 29891560 DOI: 10.1101/cshperspect.a032862] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is arguably the best-studied eukaryotic messenger RNA (mRNA) surveillance pathway, yet fundamental questions concerning the molecular mechanism of target RNA selection remain unsolved. Besides degrading defective mRNAs harboring premature termination codons (PTCs), NMD also targets many mRNAs encoding functional full-length proteins. Thus, NMD impacts on a cell's transcriptome and is implicated in a range of biological processes that affect a broad spectrum of cellular homeostasis. Here, we focus on the steps involved in the recognition of NMD targets and the activation of NMD. We summarize the accumulating evidence that tightly links NMD to translation termination and we further discuss the recruitment and activation of the mRNA degradation machinery and the regulation of this complex series of events. Finally, we review emerging ideas concerning the mechanistic details of NMD activation and the potential role of NMD as a general surveyor of translation efficacy.
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Affiliation(s)
- Evangelos D Karousis
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
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36
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Fernandes R, Nogueira G, da Costa PJ, Pinto F, Romão L. Nonsense-Mediated mRNA Decay in Development, Stress and Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1157:41-83. [DOI: 10.1007/978-3-030-19966-1_3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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37
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Kovács Á, Dudola D, Nyitray L, Tóth G, Nagy Z, Gáspári Z. Detection of single alpha-helices in large protein sequence sets using hardware acceleration. J Struct Biol 2018; 204:109-116. [PMID: 29908248 DOI: 10.1016/j.jsb.2018.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 06/11/2018] [Accepted: 06/12/2018] [Indexed: 12/13/2022]
Abstract
Single alpha-helices (SAHs) are increasingly recognized as important structural and functional elements of proteins. Comprehensive identification of SAH segments in large protein datasets was largely hindered by the slow speed of the most restrictive prediction tool for their identification, FT_CHARGE on common hardware. We have previously implemented an FPGA-based version of this tool allowing fast analysis of a large number of sequences. Using this implementation, we have set up of a semi-automated pipeline capable of analyzing full UniProt releases in reasonable time and compiling monthly updates of a comprehensive database of SAH segments. Releases of this database, denoted CSAHDB, is available on the CSAHserver 2 website at csahserver.itk.ppke.hu. An overview of human SAH-containing sequences combined with a literature survey suggests specific roles of SAH segments in proteins involved in RNA-based regulation processes as well as cytoskeletal proteins, a number of which is also linked to the development and function of synapses.
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Affiliation(s)
- Ákos Kovács
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - Dániel Dudola
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
| | - László Nyitray
- Department of Biochemistry, Eötvös Loránd University, Budapest, Hungary
| | - Gábor Tóth
- Department for Research and Development, National Research, Development and Innovation Office, Budapest, Hungary
| | - Zoltán Nagy
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.
| | - Zoltán Gáspári
- Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.
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38
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HTLV-1 Tax plugs and freezes UPF1 helicase leading to nonsense-mediated mRNA decay inhibition. Nat Commun 2018; 9:431. [PMID: 29382845 PMCID: PMC5789848 DOI: 10.1038/s41467-017-02793-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Accepted: 12/28/2017] [Indexed: 12/19/2022] Open
Abstract
Up-Frameshift Suppressor 1 Homolog (UPF1) is a key factor for nonsense-mediated mRNA decay (NMD), a cellular process that can actively degrade mRNAs. Here, we study NMD inhibition during infection by human T-cell lymphotropic virus type I (HTLV-1) and characterise the influence of the retroviral Tax factor on UPF1 activity. Tax interacts with the central helicase core domain of UPF1 and might plug the RNA channel of UPF1, reducing its affinity for nucleic acids. Furthermore, using a single-molecule approach, we show that the sequential interaction of Tax with a RNA-bound UPF1 freezes UPF1: this latter is less sensitive to the presence of ATP and shows translocation defects, highlighting the importance of this feature for NMD. These mechanistic insights reveal how HTLV-1 hijacks the central component of NMD to ensure expression of its own genome. UPF1 is a central protein in nonsense-mediated mRNA decay (NMD), but contribution of its RNA processivity to NMD is unclear. Here, the authors show how the retroviral Tax protein interacts with and inhibits UPF1, and demonstrate that UPF1’s translocase activity contributes to NMD.
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39
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Lejeune F. Nonsense-mediated mRNA decay at the crossroads of many cellular pathways. BMB Rep 2018; 50:175-185. [PMID: 28115040 PMCID: PMC5437961 DOI: 10.5483/bmbrep.2017.50.4.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Indexed: 12/22/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism ensuring the fast decay of mRNAs harboring a premature termination codon (PTC). As a quality control mechanism, NMD distinguishes PTCs from normal termination codons in order to degrade PTC-carrying mRNAs only. For this, NMD is connected to various other cell processes which regulate or activate it under specific cell conditions or in response to mutations, mis-regulations, stresses, or particular cell programs. These cell processes and their connections with NMD are the focus of this review, which aims both to illustrate the complexity of the NMD mechanism and its regulation and to highlight the cellular consequences of NMD inhibition.
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Affiliation(s)
- Fabrice Lejeune
- University Lille, UMR8161 - M3T - Mechanisms of Tumorigenesis and Target Therapies; CNRS, UMR 8161, 3Institut Pasteur de Lille, F-59000 Lille, France
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40
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Abstract
Ribonucleic acid (RNA) homeostasis is dynamically modulated in response to changing physiological conditions. Tight regulation of RNA abundance through both transcription and degradation determines the amount, timing, and location of protein translation. This balance is of particular importance in neurons, which are among the most metabolically active and morphologically complex cells in the body. As a result, any disruptions in RNA degradation can have dramatic consequences for neuronal health. In this chapter, we will first discuss mechanisms of RNA stabilization and decay. We will then explore how the disruption of these pathways can lead to neurodegenerative disease.
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41
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Gupta P, Li YR. Upf proteins: highly conserved factors involved in nonsense mRNA mediated decay. Mol Biol Rep 2017; 45:39-55. [PMID: 29282598 DOI: 10.1007/s11033-017-4139-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/14/2017] [Indexed: 11/28/2022]
Abstract
Over 10% of genetic diseases are caused by mutations that introduce a premature termination codon in protein-coding mRNA. Nonsense-mediated mRNA decay (NMD) is an essential cellular pathway that degrades these mRNAs to prevent the accumulation of harmful partial protein products. NMD machinery is also increasingly appreciated to play a role in other essential cellular functions, including telomere homeostasis and the regulation of normal mRNA turnover, and is misregulated in numerous cancers. Hence, understanding and designing therapeutics targeting NMD is an important goal in biomedical science. The central regulator of NMD, the Upf1 protein, interacts with translation termination factors and contextual factors to initiate NMD specifically on mRNAs containing PTCs. The molecular details of how these contextual factors affect Upf1 function remain poorly understood. Here, we review plausible models for the NMD pathway and the evidence for the variety of roles NMD machinery may play in different cellular processes.
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Affiliation(s)
- Puneet Gupta
- Harvard College, Harvard University, Cambridge, MA, 02138, USA.,School of Arts and Sciences, St. Bonaventure University, St. Bonaventure, NY, 14778, USA
| | - Yan-Ruide Li
- Harvard Medical School, Harvard University, Boston, MA, 02115, USA. .,College of Life Sciences, Zhejiang University, 866 Yu Hang Tang Road, Hangzhou, 310058, China.
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42
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Díaz-Santín LM, Lukoyanova N, Aciyan E, Cheung AC. Cryo-EM structure of the SAGA and NuA4 coactivator subunit Tra1 at 3.7 angstrom resolution. eLife 2017; 6:28384. [PMID: 28767037 PMCID: PMC5576489 DOI: 10.7554/elife.28384] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 07/31/2017] [Indexed: 01/30/2023] Open
Abstract
Coactivator complexes SAGA and NuA4 stimulate transcription by post-translationally modifying chromatin. Both complexes contain the Tra1 subunit, a highly conserved 3744-residue protein from the Phosphoinositide 3-Kinase-related kinase (PIKK) family and a direct target for multiple sequence-specific activators. We present the Cryo-EM structure of Saccharomyces cerevsisae Tra1 to 3.7 Å resolution, revealing an extensive network of alpha-helical solenoids organized into a diamond ring conformation and is strikingly reminiscent of DNA-PKcs, suggesting a direct role for Tra1 in DNA repair. The structure was fitted into an existing SAGA EM reconstruction and reveals limited contact surfaces to Tra1, hence it does not act as a molecular scaffold within SAGA. Mutations that affect activator targeting are distributed across the Tra1 structure, but also cluster within the N-terminal Finger region, indicating the presence of an activator interaction site. The structure of Tra1 is a key milestone in deciphering the mechanism of multiple coactivator complexes. Inside our cells, histone proteins package and condense DNA so that it can fit into the cell nucleus. However, this also switches off the genes, since the machines that read and interpret them can no longer access the underlying DNA. Turning genes on requires specific enzymes that chemically modify the histone proteins to regain access to the DNA. This must be carefully controlled, otherwise the ‘wrong’ genes can be activated, causing undesired effects and endangering the cell. Histone modifying enzymes often reside in large protein complexes. Two well-known examples are the SAGA and NuA4 complexes. Both have different roles during gene activation, but share a protein called Tra1. This protein enables SAGA and NuA4 to act on specific genes by binding to ‘activator proteins’ that are found on the DNA. Tra1 is one of the biggest proteins in the cell, but its size makes it difficult to study and until now, its structure was unknown. To determine the structure of Tra1, Díaz-Santín et al. extracted the protein from baker’s yeast, and examined it using electron microscopy. The structure of Tra1 resembled a diamond ring with multiple protein domains that correspond to a band, setting and a centre stone. The structure was detailed enough so that Díaz-Santín et al. could locate various mutations that affect the role of Tra1. These locations are likely to be direct interfaces to the ‘activator proteins’. Moreover, the study showed that Tra1 was similar to another protein that repairs damaged DNA. These results suggest that Tra1 not only works as an activator target, but may also have a role in repairing damaged DNA, and might even connect these two processes. Yeast Tra1 is also very similar to its human counterpart, which has been shown to stimulate cells to become cancerous. Further studies based on these results may help us understand how cancer begins.
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Affiliation(s)
- Luis Miguel Díaz-Santín
- Department of Structural and Molecular Biology, Institute of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Natasha Lukoyanova
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
| | - Emir Aciyan
- Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
| | - Alan Cm Cheung
- Department of Structural and Molecular Biology, Institute of Structural and Molecular Biology, University College London, London, United Kingdom.,Institute of Structural and Molecular Biology, Biological Sciences, Birkbeck College, London, United Kingdom
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43
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da Costa PJ, Menezes J, Romão L. The role of alternative splicing coupled to nonsense-mediated mRNA decay in human disease. Int J Biochem Cell Biol 2017; 91:168-175. [PMID: 28743674 DOI: 10.1016/j.biocel.2017.07.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/15/2017] [Accepted: 07/18/2017] [Indexed: 12/29/2022]
Abstract
Alternative pre-mRNA splicing (AS) affects gene expression as it generates proteome diversity. Nonsense-mediated mRNA decay (NMD) is a surveillance pathway that recognizes and selectively degrades mRNAs carrying premature translation-termination codons (PTCs), preventing the production of truncated proteins that could result in disease. Several studies have also implicated NMD in the regulation of steady-state levels of physiological mRNAs. In addition, it is known that several regulated AS events do not lead to generation of protein products, as they lead to transcripts that carry PTCs and thus, they are committed to NMD. Indeed, an estimated one-third of naturally occurring, alternatively spliced mRNAs is targeted for NMD, being AS coupled to NMD (AS-NMD) an efficient strategy to regulate gene expression. In this review, we will focus on how AS mechanism operates and how can be coupled to NMD to fine-tune gene expression levels. Furthermore, we will demonstrate the physiological significance of the interplay among AS and NMD in human disease, such as cancer and neurological disorders. The understanding of how AS-NMD orchestrates expression of vital genes is of utmost importance for the advance in diagnosis, prognosis and treatment of many human disorders.
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Affiliation(s)
- Paulo J da Costa
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal; Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Juliane Menezes
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal; Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
| | - Luísa Romão
- Department of Human Genetics, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisbon, Portugal; Biosystems & Integrative Sciences Institute (BioISI), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal.
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44
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Li L, Lingaraju M, Basquin C, Basquin J, Conti E. Structure of a SMG8-SMG9 complex identifies a G-domain heterodimer in the NMD effector proteins. RNA (NEW YORK, N.Y.) 2017; 23:1028-1034. [PMID: 28389433 PMCID: PMC5473137 DOI: 10.1261/rna.061200.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/04/2017] [Indexed: 06/07/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a eukaryotic mRNA degradation pathway involved in surveillance and post-transcriptional regulation, and executed by the concerted action of several trans-acting factors. The SMG1 kinase is an essential NMD factor in metazoans and is associated with two recently identified and yet poorly characterized proteins, SMG8 and SMG9. We determined the 2.5 Å resolution crystal structure of a SMG8-SMG9 core complex from C. elegans We found that SMG8-SMG9 is a G-domain heterodimer with architectural similarities to the dynamin-like family of GTPases such as Atlastin and GBP1. The SMG8-SMG9 heterodimer forms in the absence of nucleotides, with interactions conserved from worms to humans. Nucleotide binding occurs at the G domain of SMG9 but not of SMG8. Fitting the GDP-bound SMG8-SMG9 structure in EM densities of the human SMG1-SMG8-SMG9 complex raises the possibility that the nucleotide site of SMG9 faces SMG1 and could impact the kinase conformation and/or regulation.
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Affiliation(s)
- Liang Li
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Mahesh Lingaraju
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Claire Basquin
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Jérome Basquin
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
| | - Elena Conti
- Department of Structural Cell Biology, Max-Planck-Institute of Biochemistry, D-82152 Martinsried, Germany
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45
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Balistreri G, Bognanni C, Mühlemann O. Virus Escape and Manipulation of Cellular Nonsense-Mediated mRNA Decay. Viruses 2017; 9:v9010024. [PMID: 28124995 PMCID: PMC5294993 DOI: 10.3390/v9010024] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 01/05/2017] [Accepted: 01/13/2017] [Indexed: 12/13/2022] Open
Abstract
Nonsense-mediated mRNA decay (NMD), a cellular RNA turnover pathway targeting RNAs with features resulting in aberrant translation termination, has recently been found to restrict the replication of positive-stranded RNA ((+)RNA) viruses. As for every other antiviral immune system, there is also evidence of viruses interfering with and modulating NMD to their own advantage. This review will discuss our current understanding of why and how NMD targets viral RNAs, and elaborate counter-defense strategies viruses utilize to escape NMD.
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Affiliation(s)
- Giuseppe Balistreri
- Department of Biosciences, University of Helsinki, Helsinki FIN-00014, Finland.
| | - Claudia Bognanni
- Department of Chemistry and Biochemistry, University of Bern, Bern CH-3012, Switzerland.
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern CH-3012, Switzerland.
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, Bern CH-3012, Switzerland.
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46
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Abstract
Viruses have evolved diverse strategies to maximize the functional and coding capacities of their genetic material. Individual viral RNAs are often used as substrates for both replication and translation and can contain multiple, sometimes overlapping open reading frames. Further, viral RNAs engage in a wide variety of interactions with both host and viral proteins to modify the activities of important cellular factors and direct their own trafficking, packaging, localization, stability, and translation. However, adaptations increasing the information density of small viral genomes can have unintended consequences. In particular, viral RNAs have developed features that mark them as potential targets of host RNA quality control pathways. This minireview focuses on ways in which viral RNAs run afoul of the cellular mRNA quality control and decay machinery, as well as on strategies developed by viruses to circumvent or exploit cellular mRNA surveillance.
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47
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Karousis ED, Nasif S, Mühlemann O. Nonsense-mediated mRNA decay: novel mechanistic insights and biological impact. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:661-82. [PMID: 27173476 PMCID: PMC6680220 DOI: 10.1002/wrna.1357] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/31/2016] [Accepted: 04/04/2016] [Indexed: 12/19/2022]
Abstract
Nonsense‐mediated mRNA decay (NMD) was originally coined to define a quality control mechanism that targets mRNAs with truncated open reading frames due to the presence of a premature termination codon. Meanwhile, it became clear that NMD has a much broader impact on gene expression and additional biological functions beyond quality control are continuously being discovered. We review here the current views regarding the molecular mechanisms of NMD, according to which NMD ensues on mRNAs that fail to terminate translation properly, and point out the gaps in our understanding. We further summarize the recent literature on an ever‐rising spectrum of biological processes in which NMD appears to be involved, including homeostatic control of gene expression, development and differentiation, as well as viral defense. WIREs RNA 2016, 7:661–682. doi: 10.1002/wrna.1357 This article is categorized under:
RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Turnover and Surveillance > Regulation of RNA Stability
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Affiliation(s)
| | - Sofia Nasif
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
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Sawicka M, Wanrooij PH, Darbari VC, Tannous E, Hailemariam S, Bose D, Makarova AV, Burgers PM, Zhang X. The Dimeric Architecture of Checkpoint Kinases Mec1ATR and Tel1ATM Reveal a Common Structural Organization. J Biol Chem 2016; 291:13436-47. [PMID: 27129217 PMCID: PMC4919432 DOI: 10.1074/jbc.m115.708263] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Indexed: 12/21/2022] Open
Abstract
The phosphatidylinositol 3-kinase-related protein kinases are key regulators controlling a wide range of cellular events. The yeast Tel1 and Mec1·Ddc2 complex (ATM and ATR-ATRIP in humans) play pivotal roles in DNA replication, DNA damage signaling, and repair. Here, we present the first structural insight for dimers of Mec1·Ddc2 and Tel1 using single-particle electron microscopy. Both kinases reveal a head to head dimer with one major dimeric interface through the N-terminal HEAT (named after Huntingtin, elongation factor 3, protein phosphatase 2A, and yeast kinase TOR1) repeat. Their dimeric interface is significantly distinct from the interface of mTOR complex 1 dimer, which oligomerizes through two spatially separate interfaces. We also observe different structural organizations of kinase domains of Mec1 and Tel1. The kinase domains in the Mec1·Ddc2 dimer are located in close proximity to each other. However, in the Tel1 dimer they are fully separated, providing potential access of substrates to this kinase, even in its dimeric form.
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Affiliation(s)
- Marta Sawicka
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Paulina H Wanrooij
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Vidya C Darbari
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Elias Tannous
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Sarem Hailemariam
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Daniel Bose
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
| | - Alena V Makarova
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Peter M Burgers
- the Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Xiaodong Zhang
- From the Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington, London SW7 2AZ, United Kingdom and
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49
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Baretić D, Berndt A, Ohashi Y, Johnson CM, Williams RL. Tor forms a dimer through an N-terminal helical solenoid with a complex topology. Nat Commun 2016; 7:11016. [PMID: 27072897 PMCID: PMC4833857 DOI: 10.1038/ncomms11016] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 02/11/2016] [Indexed: 01/18/2023] Open
Abstract
The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a range of anabolic and catabolic processes. Tor is present in two complexes, TORC1 and TORC2, in which the Tor–Lst8 heterodimer forms a common sub-complex. We have determined the cryo-electron microscopy (EM) structure of Tor bound to Lst8. Two Tor–Lst8 heterodimers assemble further into a dyad-symmetry dimer mediated by Tor–Tor interactions. The first 1,300 residues of Tor form a HEAT repeat-containing α-solenoid with four distinct segments: a highly curved 800-residue N-terminal 'spiral', followed by a 400-residue low-curvature 'bridge' and an extended ‘railing' running along the bridge leading to the 'cap' that links to FAT region. This complex topology was verified by domain insertions and offers a new interpretation of the mTORC1 structure. The spiral of one TOR interacts with the bridge of another, which together form a joint platform for the Regulatory Associated Protein of TOR (RAPTOR) regulatory subunit. The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a wide range of anabolic and catabolic processes. Here the authors describe a sub-nanometer cryo-EM structure of a yeast Tor–Lst8 complex and propose an overall topology that differs from that previously suggested for mTORC1.
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Affiliation(s)
| | - Alex Berndt
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Yohei Ohashi
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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The RNA helicase DHX34 functions as a scaffold for SMG1-mediated UPF1 phosphorylation. Nat Commun 2016; 7:10585. [PMID: 26841701 PMCID: PMC4743010 DOI: 10.1038/ncomms10585] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 12/31/2015] [Indexed: 02/05/2023] Open
Abstract
Nonsense-mediated decay (NMD) is a messenger RNA quality-control pathway triggered by SMG1-mediated phosphorylation of the NMD factor UPF1. In recent times, the RNA helicase DHX34 was found to promote mRNP remodelling, leading to activation of NMD. Here we demonstrate the mechanism by which DHX34 functions in concert with SMG1. DHX34 comprises two distinct structural units, a core that binds UPF1 and a protruding carboxy-terminal domain (CTD) that binds the SMG1 kinase, as shown using truncated forms of DHX34 and electron microscopy of the SMG1–DHX34 complex. Truncation of the DHX34 CTD does not affect binding to UPF1; however, it compromises DHX34 binding to SMG1 to affect UPF1 phosphorylation and hence abrogate NMD. Altogether, these data suggest the existence of a complex comprising SMG1, UPF1 and DHX34, with DHX34 functioning as a scaffold for UPF1 and SMG1. This complex promotes UPF1 phosphorylation leading to functional NMD. UPF1 is a central Nonsense-mediated mRNA decay—(NMD), a mechanism to degrade mRNAs containing premature translation termination codons-factor—whose phosphorylation is key to triggering NMD. Here the authors show that the DHX34 helicase acts as a scaffold in promoting UPF1 phosphorylation by SMG1 to promotes NMD.
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