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Mars JC, Culjkovic-Kraljacic B, Borden KLB. eIF4E orchestrates mRNA processing, RNA export and translation to modify specific protein production. Nucleus 2024; 15:2360196. [PMID: 38880976 DOI: 10.1080/19491034.2024.2360196] [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: 02/12/2024] [Accepted: 05/22/2024] [Indexed: 06/18/2024] Open
Abstract
The eukaryotic translation initiation factor eIF4E acts as a multifunctional factor that simultaneously influences mRNA processing, export, and translation in many organisms. Its multifactorial effects are derived from its capacity to bind to the methyl-7-guanosine cap on the 5'end of mRNAs and thus can act as a cap chaperone for transcripts in the nucleus and cytoplasm. In this review, we describe the multifactorial roles of eIF4E in major mRNA-processing events including capping, splicing, cleavage and polyadenylation, nuclear export and translation. We discuss the evidence that eIF4E acts at two levels to generate widescale changes to processing, export and ultimately the protein produced. First, eIF4E alters the production of components of the mRNA processing machinery, supporting a widescale reprogramming of multiple mRNA processing events. In this way, eIF4E can modulate mRNA processing without physically interacting with target transcripts. Second, eIF4E also physically interacts with both capped mRNAs and components of the RNA processing or translation machineries. Further, specific mRNAs are sensitive to eIF4E only in particular mRNA processing events. This selectivity is governed by the presence of cis-acting elements within mRNAs known as USER codes that recruit relevant co-factors engaging the appropriate machinery. In all, we describe the molecular bases for eIF4E's multifactorial function and relevant regulatory pathways, discuss the basis for selectivity, present a compendium of ~80 eIF4E-interacting factors which play roles in these activities and provide an overview of the relevance of its functions to its oncogenic potential. Finally, we summarize early-stage clinical studies targeting eIF4E in cancer.
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Affiliation(s)
- Jean-Clément Mars
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Biljana Culjkovic-Kraljacic
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
| | - Katherine L B Borden
- Institute of Research in Immunology and Cancer, Department of Pathology and Cell Biology, Université de Montréal, Montréal, QC, Canada
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2
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Yellamaty R, Sharma S. Critical Cellular Functions and Mechanisms of Action of the RNA Helicase UAP56. J Mol Biol 2024; 436:168604. [PMID: 38729260 PMCID: PMC11168752 DOI: 10.1016/j.jmb.2024.168604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/24/2024] [Accepted: 05/03/2024] [Indexed: 05/12/2024]
Abstract
Posttranscriptional maturation and export from the nucleus to the cytoplasm are essential steps in the normal processing of many cellular RNAs. The RNA helicase UAP56 (U2AF associated protein 56; also known as DDX39B) has emerged as a critical player in facilitating and co-transcriptionally linking these steps. Originally identified as a helicase involved in pre-mRNA splicing, UAP56 has been shown to facilitate formation of the A complex during spliceosome assembly. Additionally, it has been found to be critical for interactions between components of the exon junction and transcription and export complexes to promote the loading of export receptors. Although it appears to be structurally similar to other helicase superfamily 2 members, UAP56's ability to interact with multiple different protein partners allows it to perform its various cellular functions. Herein, we describe the structure-activity relationship studies that identified protein interactions of UAP56 and its human paralog URH49 (UAP56-related helicase 49; also known as DDX39A) and are beginning to reveal molecular mechanisms by which interacting proteins and substrate RNAs may regulate these helicases. We also provide an overview of reports that have demonstrated less well-characterized roles for UAP56, including R-loop resolution and telomere maintenance. Finally, we discuss studies that indicate a potential pathogenic effect of UAP56 in the development of autoimmune diseases and cancer, and identify the association of somatic and genetic mutations in UAP56 with neurodevelopmental disorders.
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Affiliation(s)
- Ryan Yellamaty
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
| | - Shalini Sharma
- Department of Basic Medical Sciences, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA.
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3
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Mei M, Cupic A, Miorin L, Ye C, Cagatay T, Zhang K, Patel K, Wilson N, McDonald WH, Crossland NA, Lo M, Rutkowska M, Aslam S, Mena I, Martinez-Sobrido L, Ren Y, García-Sastre A, Fontoura BMA. Inhibition of mRNA nuclear export promotes SARS-CoV-2 pathogenesis. Proc Natl Acad Sci U S A 2024; 121:e2314166121. [PMID: 38768348 PMCID: PMC11145185 DOI: 10.1073/pnas.2314166121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 04/09/2024] [Indexed: 05/22/2024] Open
Abstract
The nonstructural protein 1 (Nsp1) of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) is a virulence factor that targets multiple cellular pathways to inhibit host gene expression and antiviral response. However, the underlying mechanisms of the various Nsp1-mediated functions and their contributions to SARS-CoV-2 virulence remain unclear. Among the targets of Nsp1 is the mRNA (messenger ribonucleic acid) export receptor NXF1-NXT1, which mediates nuclear export of mRNAs from the nucleus to the cytoplasm. Based on Nsp1 crystal structure, we generated mutants on Nsp1 surfaces and identified an acidic N-terminal patch that is critical for interaction with NXF1-NXT1. Photoactivatable Nsp1 probe reveals the RNA Recognition Motif (RRM) domain of NXF1 as an Nsp1 N-terminal binding site. By mutating the Nsp1 N-terminal acidic patch, we identified a separation-of-function mutant of Nsp1 that retains its translation inhibitory function but substantially loses its interaction with NXF1 and reverts Nsp1-mediated mRNA export inhibition. We then generated a recombinant (r)SARS-CoV-2 mutant on the Nsp1 N-terminal acidic patch and found that this surface is key to promote NXF1 binding and inhibition of host mRNA nuclear export, viral replication, and pathogenicity in vivo. Thus, these findings provide a mechanistic understanding of Nsp1-mediated mRNA export inhibition and establish the importance of this pathway in the virulence of SARS-CoV-2.
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Affiliation(s)
- Menghan Mei
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Anastasija Cupic
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Lisa Miorin
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Chengjin Ye
- Texas Biomedical Research Institute, San Antonio, TX78227
| | - Tolga Cagatay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
| | - Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
- Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai200031, China
| | - Komal Patel
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
- Arpirnaut Program, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Natalie Wilson
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - W. Hayes McDonald
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Nicholas A. Crossland
- Comparative Pathology Laboratory, National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA02215
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, MA02118
| | - Ming Lo
- Comparative Pathology Laboratory, National Emerging Infectious Diseases Laboratories, Boston University, Boston, MA02215
| | - Magdalena Rutkowska
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Sadaf Aslam
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Ignacio Mena
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | | | - Yi Ren
- Department of Biochemistry, Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN37232
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY10029
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY10029
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY10029
| | - Beatriz M. A. Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX75390
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4
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Shakhi PK, Bijeesh MM, Hareesh J, Joseph T, Nandakumar P, K. Varier G. Size-dependent steady state saturation limit in biomolecular transport through nuclear membranes. PLoS One 2024; 19:e0297738. [PMID: 38626108 PMCID: PMC11020410 DOI: 10.1371/journal.pone.0297738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 01/11/2024] [Indexed: 04/18/2024] Open
Abstract
The nucleus preserves the genomic DNA of eukaryotic organisms and maintains the integrity of the cell by regulating the transport of molecules across the nuclear membrane. It is hitherto assumed that small molecules having a size below the passive permeability limit are allowed to diffuse freely to the nucleus while the transport of larger molecules is regulated via an active mechanism involving energy. Here we report on the kinetics of nuclear import and export of dextran molecules having a size below the passive permeability limit. The studies carried out using time-lapse confocal fluorescence microscopy show a clear deviation from the passive diffusion model. In particular, it is observed that the steady-state concentration of dextran molecules inside the nucleus is consistently less than the concentration outside, in contradiction to the predictions of the passive diffusion model. Detailed analysis and modeling of the transport show that the nuclear export rates significantly differ from the import rates, and the difference in rates is dependent on the size of the molecules. The nuclear export rates are further confirmed by an independent experimental study where we observe the diffusion of dextran molecules from the nucleus directly. Our experiments and transport model would suggest that the nucleus actively rejects exogenous macromolecules even below the passive permeability limit. This result can have a significant impact on biomedical research, especially in areas related to targeted drug delivery and gene therapy.
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Affiliation(s)
- P. K. Shakhi
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
| | - M. M. Bijeesh
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
| | - J. Hareesh
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
| | - Toby Joseph
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
| | - P. Nandakumar
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
| | - Geetha K. Varier
- Department of Physics, BITS Pilani K. K. Birla Goa Campus, Goa, India
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5
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Werren EA, LaForce GR, Srivastava A, Perillo DR, Li S, Johnson K, Baris S, Berger B, Regan SL, Pfennig CD, de Munnik S, Pfundt R, Hebbar M, Jimenez-Heredia R, Karakoc-Aydiner E, Ozen A, Dmytrus J, Krolo A, Corning K, Prijoles EJ, Louie RJ, Lebel RR, Le TL, Amiel J, Gordon CT, Boztug K, Girisha KM, Shukla A, Bielas SL, Schaffer AE. TREX tetramer disruption alters RNA processing necessary for corticogenesis in THOC6 Intellectual Disability Syndrome. Nat Commun 2024; 15:1640. [PMID: 38388531 PMCID: PMC10884030 DOI: 10.1038/s41467-024-45948-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 02/07/2024] [Indexed: 02/24/2024] Open
Abstract
THOC6 variants are the genetic basis of autosomal recessive THOC6 Intellectual Disability Syndrome (TIDS). THOC6 is critical for mammalian Transcription Export complex (TREX) tetramer formation, which is composed of four six-subunit THO monomers. The TREX tetramer facilitates mammalian RNA processing, in addition to the nuclear mRNA export functions of the TREX dimer conserved through yeast. Human and mouse TIDS model systems revealed novel THOC6-dependent, species-specific TREX tetramer functions. Germline biallelic Thoc6 loss-of-function (LOF) variants result in mouse embryonic lethality. Biallelic THOC6 LOF variants reduce the binding affinity of ALYREF to THOC5 without affecting the protein expression of TREX members, implicating impaired TREX tetramer formation. Defects in RNA nuclear export functions were not detected in biallelic THOC6 LOF human neural cells. Instead, mis-splicing was detected in human and mouse neural tissue, revealing novel THOC6-mediated TREX coordination of mRNA processing. We demonstrate that THOC6 is required for key signaling pathways known to regulate the transition from proliferative to neurogenic divisions during human corticogenesis. Together, these findings implicate altered RNA processing in the developmental biology of TIDS neuropathology.
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Affiliation(s)
- Elizabeth A Werren
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Advanced Precision Medicine Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Geneva R LaForce
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Anshika Srivastava
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
- Department of Medical Genetics, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, 226014, India
| | - Delia R Perillo
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Shaokun Li
- Advanced Precision Medicine Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Katherine Johnson
- Advanced Precision Medicine Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Safa Baris
- Division of Pediatric Allergy and Immunology, School of Medicine, Marmara University, Istanbul Jeffrey Modell Diagnostic and Research Center for Primary Immunodeficiencies, The Isil Berat Barlan Center for Translational Medicine, Istanbul, 34722, Turkey
| | - Brandon Berger
- Advanced Precision Medicine Laboratory, The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06032, USA
| | - Samantha L Regan
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Christian D Pfennig
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Sonja de Munnik
- Department of Human Genetics, Radboud University Medical Centre Nijmegen, Nijmegen, 6524, the Netherlands
| | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Centre Nijmegen, Nijmegen, 6524, the Netherlands
| | - Malavika Hebbar
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, 98195, Seattle, WA, USA
| | - Raúl Jimenez-Heredia
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, 1090, Austria
| | - Elif Karakoc-Aydiner
- Division of Pediatric Allergy and Immunology, School of Medicine, Marmara University, Istanbul Jeffrey Modell Diagnostic and Research Center for Primary Immunodeficiencies, The Isil Berat Barlan Center for Translational Medicine, Istanbul, 34722, Turkey
| | - Ahmet Ozen
- Division of Pediatric Allergy and Immunology, School of Medicine, Marmara University, Istanbul Jeffrey Modell Diagnostic and Research Center for Primary Immunodeficiencies, The Isil Berat Barlan Center for Translational Medicine, Istanbul, 34722, Turkey
| | - Jasmin Dmytrus
- Research Centre for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
| | - Ana Krolo
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, 1090, Austria
| | - Ken Corning
- Greenwood Genetic Center, Greenwood, SC, 29646, USA
| | - E J Prijoles
- Greenwood Genetic Center, Greenwood, SC, 29646, USA
| | | | - Robert Roger Lebel
- Section of Medical Genetics, SUNY Upstate Medical University, Syracuse, NY, 13210, USA
| | - Thuy-Linh Le
- Imagine Institute, INSERM U1163, Paris Cité University, Paris, 75015, France
| | - Jeanne Amiel
- Imagine Institute, INSERM U1163, Paris Cité University, Paris, 75015, France
- Service de Médecine Génomique des Maladies Rares, Hôpital Necker-Enfants Malades, AP-HP, Paris, 75015, France
| | | | - Kaan Boztug
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, 1090, Austria
- Research Centre for Molecular Medicine of the Austrian Academy of Sciences, Vienna, 1090, Austria
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, 1090, Austria
- St. Anna Children's Hospital and Children's Cancer Research Institute, Department of Pediatrics, Medical University of Vienna, Vienna, 1090, Austria
| | - Katta M Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, 576104, India
| | - Stephanie L Bielas
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
| | - Ashleigh E Schaffer
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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6
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Mistriotis P, Wisniewski EO, Si BR, Kalab P, Konstantopoulos K. Coordinated in confined migration: crosstalk between the nucleus and ion channel-mediated mechanosensation. Trends Cell Biol 2024:S0962-8924(24)00001-1. [PMID: 38290913 DOI: 10.1016/j.tcb.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 12/22/2023] [Accepted: 01/05/2024] [Indexed: 02/01/2024]
Abstract
Cell surface and intracellular mechanosensors enable cells to perceive different geometric, topographical, and physical cues. Mechanosensitive ion channels (MICs) localized at the cell surface and on the nuclear envelope (NE) are among the first to sense and transduce these signals. Beyond compartmentalizing the genome of the cell and its transcription, the nucleus also serves as a mechanical gauge of different physical and topographical features of the tissue microenvironment. In this review, we delve into the intricate mechanisms by which the nucleus and different ion channels regulate cell migration in confinement. We review evidence suggesting an interplay between macromolecular nuclear-cytoplasmic transport (NCT) and ionic transport across the cell membrane during confined migration. We also discuss the roles of the nucleus and ion channel-mediated mechanosensation, whether acting independently or in tandem, in orchestrating migratory mechanoresponses. Understanding nuclear and ion channel sensing, and their crosstalk, is critical to advancing our knowledge of cell migration in health and disease.
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Affiliation(s)
| | - Emily O Wisniewski
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA; Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Bishwa R Si
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA; Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Petr Kalab
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA; Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA; Department of Oncology, The Johns Hopkins University, Baltimore, MD 21205, USA.
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7
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Mellios N, Papageorgiou G, Gorgievski V, Maxson G, Hernandez M, Otero M, Varangis M, Dell'Orco M, Perrone-Bizzozero N, Tzavara E. Regulation of neuronal circHomer1 biogenesis by PKA/CREB/ERK-mediated pathways and effects of glutamate and dopamine receptor blockade. RESEARCH SQUARE 2024:rs.3.rs-3547375. [PMID: 38260249 PMCID: PMC10802743 DOI: 10.21203/rs.3.rs-3547375/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
There are currently only very few efficacious drug treatments for SCZ and BD, none of which can significantly ameliorate cognitive symptoms. Thus, further research is needed in elucidating molecular pathways linked to cognitive function and antipsychotic treatment. Circular RNAs (circRNAs) are stable brain-enriched non-coding RNAs, derived from the covalent back-splicing of precursor mRNA molecules. CircHomer1 is a neuronal-enriched, activity-dependent circRNA, derived from the precursor of the long HOMER1B mRNA isoform, which is significantly downregulated in the prefrontal cortex of subjects with psychosis and is able to regulate cognitive function. Even though its relevance to psychiatric disorders and its role in brain function and synaptic plasticity have been well established, little is known about the molecular mechanisms that underlie circHomer1 biogenesis in response to neuronal activity and psychiatric drug treatment. Here we suggest that the RNA-binding protein (RBP) FUS positively regulates neuronal circHomer1 expression. Furthermore, we show that the MEK/ERK and PKA/CREB pathways positively regulate neuronal circHomer1 expression, as well as promote the transcription of Fus and Eif4a3, another RBP previously shown to activate circHomer1 biogenesis. We then demonstrate via both in vitro and in vivo studies that NMDA and mGluR5 receptors are upstream modulators of circHomer1 expression. Lastly, we report that in vivo D2R antagonism increases circHomer1 expression, whereas 5HT2AR blockade reduces circHomer1 levels in multiple brain regions. Taken together, this study allows us to gain novel insights into the molecular circuits that underlie the biogenesis of a psychiatric disease-associated circRNA.
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8
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Niikura M, Fukutomi T, Mitobe J, Kobayashi F. Characterization of a nuclear transport factor 2-like domain-containing protein in Plasmodium berghei. Malar J 2024; 23:13. [PMID: 38195464 PMCID: PMC10777651 DOI: 10.1186/s12936-024-04839-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 01/03/2024] [Indexed: 01/11/2024] Open
Abstract
BACKGROUND Plasmodium lacks an mRNA export receptor ortholog, such as yeast Mex67. Yeast Mex67 contains a nuclear transport factor 2 (NTF2)-like domain, suggesting that NTF2-like domain-containing proteins might be associated with mRNA export in Plasmodium. In this study, the relationship between mRNA export and an NTF2-like domain-containing protein, PBANKA_1019700, was investigated using the ANKA strain of rodent malaria parasite Plasmodium berghei. METHODS The deletion mutant Δ1019700 was generated by introducing gene-targeting vectors into the P. berghei ANKA genome, and parasite growth and virulence were examined. To investigate whether PBANKA_1019700 is involved in mRNA export, live-cell fluorescence imaging and immunoprecipitation coupled to mass spectrometry (IP-MS) were performed using transgenic parasites expressing fusion proteins (1019700::mCherry). RESULTS Deletion of PBANKA_1019700 affected the sexual phase but not the asexual phase of malaria parasites. Live-cell fluorescence imaging showed that PBANKA_1019700 localizes to the cytoplasm. Moreover, IP-MS analysis of 1019700::mCherry indicated that PBANKA_1019700 interacts with ubiquitin-related proteins but not nuclear proteins. CONCLUSIONS PBANKA_1019700 is a noncanonical NTF2-like superfamily protein.
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Affiliation(s)
- Mamoru Niikura
- Department of Infectious Diseases, Kyorin University School of Medicine, Tokyo, Japan.
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Jiro Mitobe
- Department of Infectious Diseases, Kyorin University School of Medicine, Tokyo, Japan
| | - Fumie Kobayashi
- Department of Environmental Science, School of Life and Environmental Science, Azabu University, Kanagawa, 252-5201, Japan
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9
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Yu W, Tingey M, Kelich JM, Li Y, Yu J, Junod SL, Jiang Z, Hansen I, Good N, Yang W. Exploring Cellular Gateways: Unraveling the Secrets of Disordered Proteins within Live Nuclear Pores. RESEARCH SQUARE 2024:rs.3.rs-3504130. [PMID: 38260360 PMCID: PMC10802689 DOI: 10.21203/rs.3.rs-3504130/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Understanding the spatial organization of nucleoporins (Nups) with intrinsically disordered domains within the nuclear pore complex (NPC) is crucial for deciphering eukaryotic nucleocytoplasmic transport. Leveraging high-speed 2D single-molecule tracking and virtual 3D super-resolution microscopy in live HeLa cells, we investigated the spatial distribution of all eleven phenylalanine-glycine (FG)-rich Nups within individual NPCs. Our study reveals a nuanced landscape of FG-Nup conformations and arrangements. Five FG-Nups are steadfastly anchored at the NPC scaffold, collectively shaping a central doughnut-shaped channel, while six others exhibit heightened flexibility, extending towards the cytoplasmic and nucleoplasmic regions. Intriguingly, Nup214 and Nup153 contribute to cap-like structures that dynamically alternate between open and closed states along the nucleocytoplasmic transport axis, impacting the cytoplasmic and nuclear sides, respectively. Furthermore, Nup98, concentrated at the scaffold region, extends throughout the entire NPC while overlapping with other FG-Nups. Together, these eleven FG-Nups compose a versatile, capped trichoid channel spanning approximately 270 nm across the nuclear envelope. This adaptable trichoid channel facilitates a spectrum of pathways for passive diffusion and facilitated nucleocytoplasmic transport. Our comprehensive mapping of FG-Nup organization within live NPCs offers a unifying mechanism accommodating multiple transport pathways, thereby advancing our understanding of cellular transport processes.
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Affiliation(s)
- Wenlan Yu
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Mark Tingey
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Joseph M. Kelich
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Yichen Li
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Jingjie Yu
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Samuel L. Junod
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Zecheng Jiang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Ian Hansen
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Nacef Good
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
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10
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Abrhámová K, Groušlová M, Valentová A, Hao X, Liu B, Převorovský M, Gahura O, Půta F, Sunnerhagen P, Folk P. Truncating the spliceosomal 'rope protein' Prp45 results in Htz1 dependent phenotypes. RNA Biol 2024; 21:1-17. [PMID: 38711165 PMCID: PMC11085953 DOI: 10.1080/15476286.2024.2348896] [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] [Accepted: 04/24/2024] [Indexed: 05/08/2024] Open
Abstract
Spliceosome assembly contributes an important but incompletely understood aspect of splicing regulation. Prp45 is a yeast splicing factor which runs as an extended fold through the spliceosome, and which may be important for bringing its components together. We performed a whole genome analysis of the genetic interaction network of the truncated allele of PRP45 (prp45(1-169)) using synthetic genetic array technology and found chromatin remodellers and modifiers as an enriched category. In agreement with related studies, H2A.Z-encoding HTZ1, and the components of SWR1, INO80, and SAGA complexes represented prominent interactors, with htz1 conferring the strongest growth defect. Because the truncation of Prp45 disproportionately affected low copy number transcripts of intron-containing genes, we prepared strains carrying intronless versions of SRB2, VPS75, or HRB1, the most affected cases with transcription-related function. Intron removal from SRB2, but not from the other genes, partly repaired some but not all the growth phenotypes identified in the genetic screen. The interaction of prp45(1-169) and htz1Δ was detectable even in cells with SRB2 intron deleted (srb2Δi). The less truncated variant, prp45(1-330), had a synthetic growth defect with htz1Δ at 16°C, which also persisted in the srb2Δi background. Moreover, htz1Δ enhanced prp45(1-330) dependent pre-mRNA hyper-accumulation of both high and low efficiency splicers, genes ECM33 and COF1, respectively. We conclude that while the expression defects of low expression intron-containing genes contribute to the genetic interactome of prp45(1-169), the genetic interactions between prp45 and htz1 alleles demonstrate the sensitivity of spliceosome assembly, delayed in prp45(1-169), to the chromatin environment.
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Affiliation(s)
- Kateřina Abrhámová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Martina Groušlová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Anna Valentová
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Xinxin Hao
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Beidong Liu
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Martin Převorovský
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Ondřej Gahura
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - František Půta
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
| | - Per Sunnerhagen
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Petr Folk
- Department of Cell Biology, Faculty of Science, Charles University, Praha, Czech Republic
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11
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Clarke BP, Angelos AE, Mei M, Hill PS, Xie Y, Ren Y. Cryo-EM structure of the CBC-ALYREF complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.01.559959. [PMID: 37873070 PMCID: PMC10592852 DOI: 10.1101/2023.10.01.559959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
In eukaryotes, RNAs transcribed by RNA Pol II are modified at the 5' end with a 7-methylguanosine (m 7 G) cap, which is recognized by the nuclear cap binding complex (CBC). The CBC plays multiple important roles in mRNA metabolism including transcription, splicing, polyadenylation and export. It promotes mRNA export through direct interaction with ALYREF, which in turn links the TRanscription and EXport (TREX) complex to the 5' end of mRNA. However, the molecular mechanism for CBC mediated recruitment of the mRNA export machinery is not well understood. Here, we present the first structure of the CBC in complex with a mRNA export factor, ALYREF. The cryo-EM structure of CBC-ALYREF reveals that the RRM domain of ALYREF makes direct contacts with both the NCBP1 and NCBP2 subunits of the CBC. Comparison of CBC-ALYREF to other CBC and ALYREF containing cellular complexes provides insights into the coordinated events during mRNA transcription, splicing, and export.
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12
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Padilla‐Mejia NE, Field MC. Evolutionary, structural and functional insights in nuclear organisation and nucleocytoplasmic transport in trypanosomes. FEBS Lett 2023; 597:2501-2518. [PMID: 37789516 PMCID: PMC10953052 DOI: 10.1002/1873-3468.14747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 09/18/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023]
Abstract
One of the remarkable features of eukaryotes is the nucleus, delimited by the nuclear envelope (NE), a complex structure and home to the nuclear lamina and nuclear pore complex (NPC). For decades, these structures were believed to be mainly architectural elements and, in the case of the NPC, simply facilitating nucleocytoplasmic trafficking. More recently, the critical roles of the lamina, NPC and other NE constituents in genome organisation, maintaining chromosomal domains and regulating gene expression have been recognised. Importantly, mutations in genes encoding lamina and NPC components lead to pathogenesis in humans, while pathogenic protozoa disrupt the progression of normal development and expression of pathogenesis-related genes. Here, we review features of the lamina and NPC across eukaryotes and discuss how these elements are structured in trypanosomes, protozoa of high medical and veterinary importance, highlighting lineage-specific and conserved aspects of nuclear organisation.
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Affiliation(s)
| | - Mark C. Field
- School of Life SciencesUniversity of DundeeUK
- Institute of Parasitology, Biology CentreCzech Academy of SciencesČeské BudějoviceCzechia
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13
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Werren E, LaForce G, Srivastava A, Perillo D, Johnson K, Berger B, Regan S, Pfennig C, Baris S, de Munnik S, Pfundt R, Hebbar M, Jimenez Heredia R, Karakoc-Aydiner E, Ozen A, Dmytrus J, Krolo A, Corning K, Prijoles E, Louie R, Lebel R, Le TL, Amiel J, Gordon C, Boztug K, Girisha K, Shukla A, Bielas S, Schaffer A. Mechanisms of mRNA processing defects in inherited THOC6 intellectual disability syndrome. RESEARCH SQUARE 2023:rs.3.rs-2126145. [PMID: 37720017 PMCID: PMC10503840 DOI: 10.21203/rs.3.rs-2126145/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
THOC6 is the genetic basis of autosomal recessive THOC6 Intellectual Disability Syndrome (TIDS). THOC6 facilitates the formation of the Transcription Export complex (TREX) tetramer, composed of four THO monomers. The TREX tetramer supports mammalian mRNA processing that is distinct from yeast TREX dimer functions. Human and mouse TIDS model systems allow novel THOC6-dependent TREX tetramer functions to be investigated. Biallelic loss-of-functon(LOF) THOC6 variants do not influence the expression and localization of TREX members in human cells, but our data suggests reduced binding affinity of ALYREF. Impairment of TREX nuclear export functions were not detected in cells with biallelic THOC6 LOF. Instead, mRNA mis-splicing was observed in human and mouse neural tissue, revealing novel insights into THOC6-mediated TREX coordination of mRNA processing. We demonstrate that THOC6 is required for regulation of key signaling pathways in human corticogenesis that dictate the transition from proliferative to neurogenic divisions that may inform TIDS neuropathology.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Jasmin Dmytrus
- CeMM Research Centre for Molecular Medicine of the Austrian Academy of Sciences
| | - Ana Krolo
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases
| | | | | | | | | | - Thuy-Linh Le
- Imagine Institute, INSERM U1163, Paris Descartes University
| | | | - Christopher Gordon
- Institut National de la Santé et de la Recherche Médicale (INSERM) UMR 1163, Institut Imagine
| | - Kaan Boztug
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases
| | - Katta Girisha
- Kasturba Medical College, Manipal, Manipal Academy of Higher Education
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14
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Xie Y, Gao S, Zhang K, Bhat P, Clarke BP, Batten K, Mei M, Gazzara M, Shay JW, Lynch KW, Angelos AE, Hill PS, Ivey AL, Fontoura BMA, Ren Y. Structural basis for high-order complex of SARNP and DDX39B to facilitate mRNP assembly. Cell Rep 2023; 42:112988. [PMID: 37578863 PMCID: PMC10508174 DOI: 10.1016/j.celrep.2023.112988] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 04/10/2023] [Accepted: 07/31/2023] [Indexed: 08/16/2023] Open
Abstract
mRNA in eukaryotic cells is packaged into highly compacted ribonucleoprotein particles (mRNPs) in the nucleus and exported to the cytoplasm for translation. mRNP packaging and export require the evolutionarily conserved transcription-export (TREX) complex. TREX facilitates loading of various RNA-binding proteins on mRNA through the action of its DDX39B subunit. SARNP (Tho1 [transcriptional defect of Hpr1 by overexpression 1] in yeast) is shown to interact with DDX39B and affect mRNA export. The molecular mechanism of how SARNP recognizes DDX39B and functions in mRNP assembly is unclear. Here, we determine the crystal structure of a Tho1/DDX39B/RNA complex, revealing a multivalent interaction mediated by tandem DDX39B interacting motifs in SARNP/Tho1. The high-order complex of SARNP and DDX39B is evolutionarily conserved, and human SARNP can engage with five DDX39B molecules. RNA sequencing (RNA-seq) from SARNP knockdown cells shows the most affected RNAs in export are GC rich. Our work suggests the role of the high-order SARNP/DDX39B/RNA complex in mRNP assembly and export.
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Affiliation(s)
- Yihu Xie
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Shengyan Gao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Prasanna Bhat
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Kimberly Batten
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Menghan Mei
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Matthew Gazzara
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jerry W Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA
| | - Kristen W Lynch
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Alexia E Angelos
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Pate S Hill
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Austin L Ivey
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
| | - Beatriz M A Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039, USA.
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA.
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15
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Guo J, Zhu Y, Ma X, Shang G, Liu B, Zhang K. Virus Infection and mRNA Nuclear Export. Int J Mol Sci 2023; 24:12593. [PMID: 37628773 PMCID: PMC10454920 DOI: 10.3390/ijms241612593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for its translation into proteins. Along with transcription and translation, mRNA export through the nuclear pore complex (NPC) is an essential regulatory step in eukaryotic gene expression. Multiple factors regulate mRNA export and hence gene expression. Interestingly, proteins from certain types of viruses interact with these factors in infected cells, and such an interaction interferes with the mRNA export of the host cell in favor of viral RNA export. Thus, these viruses hijack the host mRNA nuclear export mechanism, leading to a reduction in host gene expression and the downregulation of immune/antiviral responses. On the other hand, the viral mRNAs successfully evade the host surveillance system and are efficiently exported from the nucleus to the cytoplasm for translation, which enables the continuation of the virus life cycle. Here, we present this review to summarize the mechanisms by which viruses suppress host mRNA nuclear export during infection, as well as the key strategies that viruses use to facilitate their mRNA nuclear export. These studies have revealed new potential antivirals that may be used to inhibit viral mRNA transport and enhance host mRNA nuclear export, thereby promoting host gene expression and immune responses.
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Affiliation(s)
- Jiayin Guo
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Yaru Zhu
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Xiaoya Ma
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China;
| | - Bo Liu
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
- Shanghai Huashen Institute of Microbes and Infections, Shanghai 200052, China
| | - Ke Zhang
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
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16
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Thiyagarajah K, Basic M, Hildt E. Cellular Factors Involved in the Hepatitis D Virus Life Cycle. Viruses 2023; 15:1687. [PMID: 37632029 PMCID: PMC10459925 DOI: 10.3390/v15081687] [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: 06/30/2023] [Revised: 07/30/2023] [Accepted: 08/01/2023] [Indexed: 08/27/2023] Open
Abstract
Hepatitis D virus (HDV) is a defective RNA virus with a negative-strand RNA genome encompassing less than 1700 nucleotides. The HDV genome encodes only for one protein, the hepatitis delta antigen (HDAg), which exists in two forms acting as nucleoproteins. HDV depends on the envelope proteins of the hepatitis B virus as a helper virus for packaging its ribonucleoprotein complex (RNP). HDV is considered the causative agent for the most severe form of viral hepatitis leading to liver fibrosis/cirrhosis and hepatocellular carcinoma. Many steps of the life cycle of HDV are still enigmatic. This review gives an overview of the complete life cycle of HDV and identifies gaps in knowledge. The focus is on the description of cellular factors being involved in the life cycle of HDV and the deregulation of cellular pathways by HDV with respect to their relevance for viral replication, morphogenesis and HDV-associated pathogenesis. Moreover, recent progress in antiviral strategies targeting cellular structures is summarized in this article.
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Affiliation(s)
| | | | - Eberhard Hildt
- Paul-Ehrlich-Institute, Department of Virology, D-63225 Langen, Germany; (K.T.); (M.B.)
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17
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Nascimento JF, Souza ROO, Alencar MB, Marsiccobetre S, Murillo AM, Damasceno FS, Girard RBMM, Marchese L, Luévano-Martinez LA, Achjian RW, Haanstra JR, Michels PAM, Silber AM. How much (ATP) does it cost to build a trypanosome? A theoretical study on the quantity of ATP needed to maintain and duplicate a bloodstream-form Trypanosoma brucei cell. PLoS Pathog 2023; 19:e1011522. [PMID: 37498954 PMCID: PMC10409291 DOI: 10.1371/journal.ppat.1011522] [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: 03/23/2023] [Revised: 08/08/2023] [Accepted: 06/29/2023] [Indexed: 07/29/2023] Open
Abstract
ATP hydrolysis is required for the synthesis, transport and polymerization of monomers for macromolecules as well as for the assembly of the latter into cellular structures. Other cellular processes not directly related to synthesis of biomass, such as maintenance of membrane potential and cellular shape, also require ATP. The unicellular flagellated parasite Trypanosoma brucei has a complex digenetic life cycle. The primary energy source for this parasite in its bloodstream form (BSF) is glucose, which is abundant in the host's bloodstream. Here, we made a detailed estimation of the energy budget during the BSF cell cycle. As glycolysis is the source of most produced ATP, we calculated that a single parasite produces 6.0 x 1011 molecules of ATP/cell cycle. Total biomass production (which involves biomass maintenance and duplication) accounts for ~63% of the total energy budget, while the total biomass duplication accounts for the remaining ~37% of the ATP consumption, with in both cases translation being the most expensive process. These values allowed us to estimate a theoretical YATP of 10.1 (g biomass)/mole ATP and a theoretical [Formula: see text] of 28.6 (g biomass)/mole ATP. Flagellar motility, variant surface glycoprotein recycling, transport and maintenance of transmembrane potential account for less than 30% of the consumed ATP. Finally, there is still ~5.5% available in the budget that is being used for other cellular processes of as yet unknown cost. These data put a new perspective on the assumptions about the relative energetic weight of the processes a BSF trypanosome undergoes during its cell cycle.
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Affiliation(s)
- Janaina F. Nascimento
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Rodolpho O. O. Souza
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Mayke B. Alencar
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Sabrina Marsiccobetre
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Ana M. Murillo
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Flávia S. Damasceno
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Richard B. M. M. Girard
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Letícia Marchese
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Luis A. Luévano-Martinez
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Renan W. Achjian
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
| | - Jurgen R. Haanstra
- Systems Biology Lab, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Paul A. M. Michels
- School of Biological Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ariel M. Silber
- Laboratory of Biochemistry of Tryps–LaBTryps, Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo–São Paulo, Brazil
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18
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Fradera-Sola A, Nischwitz E, Bayer ME, Luck K, Butter F. RNA-dependent interactome allows network-based assignment of RNA-binding protein function. Nucleic Acids Res 2023; 51:5162-5176. [PMID: 37070168 PMCID: PMC10250244 DOI: 10.1093/nar/gkad245] [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: 08/12/2022] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 04/19/2023] Open
Abstract
RNA-binding proteins (RBPs) form highly diverse and dynamic ribonucleoprotein complexes, whose functions determine the molecular fate of the bound RNA. In the model organism Sacchromyces cerevisiae, the number of proteins identified as RBPs has greatly increased over the last decade. However, the cellular function of most of these novel RBPs remains largely unexplored. We used mass spectrometry-based quantitative proteomics to systematically identify protein-protein interactions (PPIs) and RNA-dependent interactions (RDIs) to create a novel dataset for 40 RBPs that are associated with the mRNA life cycle. Domain, functional and pathway enrichment analyses revealed an over-representation of RNA functionalities among the enriched interactors. Using our extensive PPI and RDI networks, we revealed putative new members of RNA-associated pathways, and highlighted potential new roles for several RBPs. Our RBP interactome resource is available through an online interactive platform as a community tool to guide further in-depth functional studies and RBP network analysis (https://www.butterlab.org/RINE).
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Affiliation(s)
- Albert Fradera-Sola
- Quantitative Proteomics, Institute of Molecular Biology, D-55128 Mainz, Germany
| | - Emily Nischwitz
- Quantitative Proteomics, Institute of Molecular Biology, D-55128 Mainz, Germany
| | | | - Katja Luck
- Integrative Systems Biology, Institute of Molecular Biology, D-55128 Mainz, Germany
| | - Falk Butter
- Quantitative Proteomics, Institute of Molecular Biology, D-55128 Mainz, Germany
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19
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Kwiatek L, Landry-Voyer AM, Latour M, Yague-Sanz C, Bachand F. PABPN1 prevents the nuclear export of an unspliced RNA with a constitutive transport element and controls human gene expression via intron retention. RNA (NEW YORK, N.Y.) 2023; 29:644-662. [PMID: 36754576 PMCID: PMC10158996 DOI: 10.1261/rna.079294.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 01/12/2023] [Indexed: 05/06/2023]
Abstract
Intron retention is a type of alternative splicing where one or more introns remain unspliced in a polyadenylated transcript. Although many viral systems are known to translate proteins from mRNAs with retained introns, restriction mechanisms generally prevent export and translation of incompletely spliced mRNAs. Here, we provide evidence that the human nuclear poly(A)-binding protein, PABPN1, functions in such restrictions. Using a reporter construct in which nuclear export of an incompletely spliced mRNA is enhanced by a viral constitutive transport element (CTE), we show that PABPN1 depletion results in a significant increase in export and translation from the unspliced CTE-containing transcript. Unexpectedly, we find that inactivation of poly(A)-tail exosome targeting by depletion of PAXT components had no effect on export and translation of the unspliced reporter mRNA, suggesting a mechanism largely independent of nuclear RNA decay. Interestingly, a PABPN1 mutant selectively defective in stimulating poly(A) polymerase elongation strongly enhanced the expression of the unspliced, but not of intronless, reporter transcripts. Analysis of RNA-seq data also revealed that PABPN1 controls the expression of many human genes via intron retention. Notably, PABPN1-dependent intron retention events mostly affected 3'-terminal introns and were insensitive to PAXT and NEXT deficiencies. Our findings thus disclose a role for PABPN1 in restricting nuclear export of intron-retained transcripts and reinforce the interdependence between terminal intron splicing, 3' end processing, and polyadenylation.
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Affiliation(s)
- Lauren Kwiatek
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec, Canada J1E 4K8
| | - Anne-Marie Landry-Voyer
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec, Canada J1E 4K8
| | - Mélodie Latour
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec, Canada J1E 4K8
| | - Carlo Yague-Sanz
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec, Canada J1E 4K8
| | - Francois Bachand
- RNA Group, Department of Biochemistry and Functional Genomics, Université de Sherbrooke, Sherbrooke, Québec, Canada J1E 4K8
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20
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Pavan RR, Diniz F, El-Dahr S, Tortelote GG. Gene length is a pivotal feature to explain disparities in transcript capture between single transcriptome techniques. FRONTIERS IN BIOINFORMATICS 2023; 3:1144266. [PMID: 37122996 PMCID: PMC10132733 DOI: 10.3389/fbinf.2023.1144266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/04/2023] [Indexed: 05/02/2023] Open
Abstract
The scale and capability of single-cell and single-nucleus RNA-sequencing technologies are rapidly growing, enabling key discoveries and large-scale cell mapping operations. However, studies directly comparing technical differences between single-cell and single-nucleus RNA sequencing are still lacking. Here, we compared three paired single-cell and single-nucleus transcriptomes from three different organs (Heart, Lung and Kidney). Differently from previous studies that focused on cell classification, we explored disparities in the transcriptome output of whole cells relative to the nucleus. We found that the major cell clusters could be recovered by either technique from matched samples, but at different proportions. In 2/3 datasets (kidney and lung) we detected clusters exclusively present with single-nucleus RNA sequencing. In all three organ groups, we found that genomic and gene structural characteristics such as gene length and exon content significantly differed between the two techniques. Genes recovered with the single-nucleus RNA sequencing technique had longer sequence lengths and larger exon counts, whereas single-cell RNA sequencing captured short genes at higher rates. Furthermore, we found that when compared to the whole host genome (mouse for kidney and lung datasets and human for the heart dataset), single transcriptomes obtained with either technique skewed from the expected proportions in several points: a) coding sequence length, b) transcript length and c) genomic span; and d) distribution of genes based on exons counts. Interestingly, the top-100 DEG between the two techniques returned distinctive GO terms. Hence, the type of single transcriptome technique used affected the outcome of downstream analysis. In summary, our data revealed both techniques present disparities in RNA capture. Moreover, the biased RNA capture affected the calculations of basic cellular parameters, raising pivotal points about the limitations and advantages of either single transcriptome techniques.
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Affiliation(s)
- Ricardo R. Pavan
- Institute for Marine and Antarctic Studies (IMAS), Nubeena Crescent, Taroona, TAS, Australia
| | - Fabiola Diniz
- Section of Pediatric Nephrology, Department of Pediatrics Tulane University School of Medicine, New Orleans, LA, United States
| | - Samir El-Dahr
- Section of Pediatric Nephrology, Department of Pediatrics Tulane University School of Medicine, New Orleans, LA, United States
| | - Giovane G. Tortelote
- Section of Pediatric Nephrology, Department of Pediatrics Tulane University School of Medicine, New Orleans, LA, United States
- *Correspondence: Giovane G. Tortelote,
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21
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Tingey M, Li Y, Yu W, Young A, Yang W. Spelling out the roles of individual nucleoporins in nuclear export of mRNA. Nucleus 2022; 13:170-193. [PMID: 35593254 PMCID: PMC9132428 DOI: 10.1080/19491034.2022.2076965] [Citation(s) in RCA: 8] [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: 01/21/2022] [Revised: 05/08/2022] [Accepted: 05/09/2022] [Indexed: 11/01/2022] Open
Abstract
The Nuclear Pore Complex (NPC) represents a critical passage through the nuclear envelope for nuclear import and export that impacts nearly every cellular process at some level. Recent technological advances in the form of Auxin Inducible Degron (AID) strategies and Single-Point Edge-Excitation sub-Diffraction (SPEED) microscopy have enabled us to provide new insight into the distinct functions and roles of nuclear basket nucleoporins (Nups) upon nuclear docking and export for mRNAs. In this paper, we provide a review of our recent findings as well as an assessment of new techniques, updated models, and future perspectives in the studies of mRNA's nuclear export.
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Affiliation(s)
- Mark Tingey
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Yichen Li
- Department of Genetics, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Wenlan Yu
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Albert Young
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
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22
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Single-cell RNA-sequencing data analysis reveals a highly correlated triphasic transcriptional response to SARS-CoV-2 infection. Commun Biol 2022; 5:1302. [PMID: 36435849 PMCID: PMC9701238 DOI: 10.1038/s42003-022-04253-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 11/11/2022] [Indexed: 11/28/2022] Open
Abstract
Single-cell RNA sequencing (scRNA-seq) is currently one of the most powerful techniques available to study the transcriptional response of thousands of cells to an external perturbation. Here, we perform a pseudotime analysis of SARS-CoV-2 infection using publicly available scRNA-seq data from human bronchial epithelial cells and colon and ileum organoids. Our results reveal that, for most genes, the transcriptional response to SARS-CoV-2 infection follows a non-linear pattern characterized by an initial and a final down-regulatory phase separated by an intermediate up-regulatory stage. A correlation analysis of transcriptional profiles suggests a common mechanism regulating the mRNA levels of most genes. Interestingly, genes encoded in the mitochondria or involved in translation exhibited distinct pseudotime profiles. To explain our results, we propose a simple model where nuclear export inhibition of nsp1-sensitive transcripts will be sufficient to explain the transcriptional shutdown of SARS-CoV-2 infected cells.
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23
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Bensidoun P, Reiter T, Montpetit B, Zenklusen D, Oeffinger M. Nuclear mRNA metabolism drives selective basket assembly on a subset of nuclear pore complexes in budding yeast. Mol Cell 2022; 82:3856-3871.e6. [PMID: 36220102 PMCID: PMC10300651 DOI: 10.1016/j.molcel.2022.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 06/24/2022] [Accepted: 09/16/2022] [Indexed: 11/13/2022]
Abstract
To determine which transcripts should reach the cytoplasm for translation, eukaryotic cells have established mechanisms to regulate selective mRNA export through the nuclear pore complex (NPC). The nuclear basket, a substructure of the NPC protruding into the nucleoplasm, is thought to function as a stable platform where mRNA-protein complexes (mRNPs) are rearranged and undergo quality control prior to export, ensuring that only mature mRNAs reach the cytoplasm. Here, we use proteomic, genetic, live-cell, and single-molecule resolution microscopy approaches in budding yeast to demonstrate that basket formation is dependent on RNA polymerase II transcription and subsequent mRNP processing. We further show that while all NPCs can bind Mlp1, baskets assemble only on a subset of nucleoplasmic NPCs, and these basket-containing NPCs associate a distinct protein and RNA interactome. Taken together, our data point toward NPC heterogeneity and an RNA-dependent mechanism for functionalization of NPCs in budding yeast through nuclear basket assembly.
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Affiliation(s)
- Pierre Bensidoun
- Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC, Canada
| | - Taylor Reiter
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, USA
| | - Ben Montpetit
- Department of Viticulture and Enology, University of California, Davis, Davis, CA, USA
| | - Daniel Zenklusen
- Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC, Canada.
| | - Marlene Oeffinger
- Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada; Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC, Canada; Division of Experimental Medicine, McGill University, Montréal, QC, Canada.
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24
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Tingey M, Yang W. Unraveling docking and initiation of mRNA export through the nuclear pore complex. Bioessays 2022; 44:e2200027. [PMID: 35754154 PMCID: PMC9308666 DOI: 10.1002/bies.202200027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 05/18/2022] [Accepted: 06/03/2022] [Indexed: 11/07/2022]
Abstract
The nuclear export of mRNA through the nuclear pore complex (NPC) is a process required for the healthy functioning of human cells, making it a critical area of research. However, the geometries of mRNA and the NPC are well below the diffraction limit of light microscopy, thereby presenting significant challenges in evaluating the discrete interactions and dynamics involved in mRNA nuclear export through the native NPC. Recent advances in biotechnology and single-molecule super-resolution light microscopy have enabled researchers to gain granular insight into the specific contributions made by discrete nucleoporins in the nuclear basket of the NPC to the export of mRNA. Specifically, by expanding upon the docking step facilitated by the protein TPR in the nuclear basket as well as identifying NUP153 as being the primary nuclear basket protein initiating export through the central channel of the NPC.
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Affiliation(s)
- Mark Tingey
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
| | - Weidong Yang
- Department of Biology, Temple University, Philadelphia, Pennsylvania, USA
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25
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Gao S, Esparza M, Dehghan I, Aksenova V, Zhang K, Batten K, Ferretti MB, Begg BE, Cagatay T, Shay JW, García-Sastre A, Goldsmith EJ, Chen ZJ, Dasso M, Lynch KW, Cobb MH, Fontoura BMA. Nuclear speckle integrity and function require TAO2 kinase. Proc Natl Acad Sci U S A 2022; 119:e2206046119. [PMID: 35704758 PMCID: PMC9231605 DOI: 10.1073/pnas.2206046119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/16/2022] [Indexed: 11/18/2022] Open
Abstract
Nuclear speckles are non-membrane-bound organelles known as storage sites for messenger RNA (mRNA) processing and splicing factors. More recently, nuclear speckles have also been implicated in splicing and export of a subset of mRNAs, including the influenza virus M mRNA that encodes proteins required for viral entry, trafficking, and budding. However, little is known about how nuclear speckles are assembled or regulated. Here, we uncovered a role for the cellular protein kinase TAO2 as a constituent of nuclear speckles and as a factor required for the integrity of these nuclear bodies and for their functions in pre-mRNA splicing and trafficking. We found that a nuclear pool of TAO2 is localized at nuclear speckles and interacts with nuclear speckle factors involved in RNA splicing and nuclear export, including SRSF1 and Aly/Ref. Depletion of TAO2 or inhibition of its kinase activity disrupts nuclear speckle structure, decreasing the levels of several proteins involved in nuclear speckle assembly and splicing, including SC35 and SON. Consequently, splicing and nuclear export of influenza virus M mRNA were severely compromised and caused a disruption in the virus life cycle. In fact, low levels of TAO2 led to a decrease in viral protein levels and inhibited viral replication. Additionally, depletion or inhibition of TAO2 resulted in abnormal expression of a subset of mRNAs with key roles in viral replication and immunity. Together, these findings uncovered a function of TAO2 in nuclear speckle formation and function and revealed host requirements and vulnerabilities for influenza infection.
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Affiliation(s)
- Shengyan Gao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Matthew Esparza
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Ishmael Dehghan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Vasilisa Aksenova
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892
| | - Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kimberly Batten
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Max B. Ferretti
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Bridget E. Begg
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Tolga Cagatay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Jerry W. Shay
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Division of Infectious Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Department of Pathology, Molecular and Cell-Based Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Elizabeth J. Goldsmith
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Zhijian J. Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
- HHMI, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892
| | - Kristen W. Lynch
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104
| | - Melanie H. Cobb
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Beatriz M. A. Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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26
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Banerjee P, Markande S, Kalarikkal M, Joseph J. SUMOylation modulates the function of DDX19 in mRNA export. J Cell Sci 2022; 135:274424. [PMID: 35080244 DOI: 10.1242/jcs.259449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/13/2022] [Indexed: 11/20/2022] Open
Abstract
Nuclear export of mRNAs is a critical regulatory step in eukaryotic gene expression. The mRNA transcript undergoes extensive processing, and is loaded with a set of RNA-binding proteins (RBPs) to form export-competent messenger ribonucleoprotein particles (mRNPs) in the nucleus. During the transit of mRNPs through the nuclear pore complex (NPC), the DEAD-box ATPase - DDX19 - remodels mRNPs at the cytoplasmic side of the NPC, by removing a subset of RNA-binding proteins to terminate mRNP export. This requires the RNA-dependent ATPase activity of DDX19 and its dynamic interactions with Gle1 and Nup214. However, the regulatory mechanisms underlying these interactions are unclear. We find that DDX19 gets covalently attached with a small ubiquitin-like modifier (SUMO) at lysine 26, which enhances its interaction with Gle1. Furthermore, a SUMOylation-defective mutant of human DDX19B, K26R, failed to provide a complete rescue of the mRNA export defect caused by DDX19 depletion. Collectively, our results suggest that SUMOylation fine-tunes the function of DDX19 in mRNA export by regulating its interaction with Gle1. This study identifies SUMOylation of DDX19 as a modulatory mechanism during the mRNA export process.
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Affiliation(s)
- Poulomi Banerjee
- National Centre for Cell Science, S. P. Pune University Campus, Pune - 411007, Maharashtra State, India
| | - Shubha Markande
- National Centre for Cell Science, S. P. Pune University Campus, Pune - 411007, Maharashtra State, India
| | - Misha Kalarikkal
- National Centre for Cell Science, S. P. Pune University Campus, Pune - 411007, Maharashtra State, India
| | - Jomon Joseph
- National Centre for Cell Science, S. P. Pune University Campus, Pune - 411007, Maharashtra State, India
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27
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Karbstein K. Attacking a DEAD problem: The role of DEAD-box ATPases in ribosome assembly and beyond. Methods Enzymol 2022; 673:19-38. [PMID: 35965007 PMCID: PMC10154911 DOI: 10.1016/bs.mie.2022.03.033] [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] [Indexed: 11/30/2022]
Abstract
DEAD-box proteins are a subfamily of ATPases with similarity to RecA-type helicases that are involved in all aspects of RNA Biology. Despite their potential to regulate these processes via their RNA-dependent ATPase activity, their roles remain poorly characterized. Here I describe a roadmap to study these proteins in the context of ribosome assembly, the process that utilizes more than half of all DEAD-box proteins encoded in the yeast genome.
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Affiliation(s)
- Katrin Karbstein
- Department of Integrative Structural and Computational Biology, Scripps Florida, Jupiter, FL, United States; HHMI Faculty Scholar, Chevy Chase, MD, United States; The Skaggs Graduate School of Chemical and Biological Sciences, Scripps Florida, Jupiter, FL, United States.
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28
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Gray S, Cao W, Montpetit B, De La Cruz EM. OUP accepted manuscript. Nucleic Acids Res 2022; 50:3998-4011. [PMID: 35286399 PMCID: PMC9023272 DOI: 10.1093/nar/gkac164] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/02/2022] [Accepted: 02/25/2022] [Indexed: 11/14/2022] Open
Abstract
The DEAD-box protein Dbp5 is essential for RNA export, which involves regulation by the nucleoporins Gle1 and Nup159 at the cytoplasmic face of the nuclear pore complex (NPC). Mechanistic understanding of how these nucleoporins regulate RNA export requires analyses of the intrinsic and activated Dbp5 ATPase cycle. Here, kinetic and equilibrium analyses of the Saccharomyces cerevisiae Gle1-activated Dbp5 ATPase cycle are presented, indicating that Gle1 and ATP, but not ADP-Pi or ADP, binding to Dbp5 are thermodynamically coupled. As a result, Gle1 binds Dbp5-ATP > 100-fold more tightly than Dbp5 in other nucleotide states and Gle1 equilibrium binding of ATP to Dbp5 increases >150-fold via slowed ATP dissociation. Second, Gle1 accelerated Dbp5 ATPase activity by increasing the rate-limiting Pi release rate constant ∼20-fold, which remains rate limiting. These data show that Gle1 activates Dbp5 by modulating ATP binding and Pi release. These Gle1 activities are expected to facilitate ATPase cycling, ensuring a pool of ATP bound Dbp5 at NPCs to engage RNA during export. This work provides a mechanism of Gle1-activation of Dbp5 and a framework to understand the joint roles of Gle1, Nup159, and other nucleoporins in regulating Dbp5 to mediate RNA export and other Dbp5 functions in gene expression.
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Affiliation(s)
- Shawn Gray
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Wenxiang Cao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA
| | - Ben Montpetit
- Department of Viticulture and Enology, University of California, Davis, Davis, CA 95616, USA
- Department of Food Science and Technology, University of California, Davis, Davis, CA 95616, USA
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29
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Vasudevan S, Baraniuk JN. Understanding COVID-19 Pathogenesis: A Drug-Repurposing Effort to Disrupt Nsp-1 Binding to Export Machinery Receptor Complex. Pathogens 2021; 10:1634. [PMID: 34959589 PMCID: PMC8709492 DOI: 10.3390/pathogens10121634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/06/2021] [Accepted: 12/15/2021] [Indexed: 11/16/2022] Open
Abstract
Non-structural protein 1 (Nsp1) is a virulence factor found in all beta coronaviruses (b-CoVs). Recent studies have shown that Nsp1 of SARS-CoV-2 virus interacts with the nuclear export receptor complex, which includes nuclear RNA export factor 1 (NXF1) and nuclear transport factor 2-like export factor 1 (NXT1). The NXF1-NXT1 complex plays a crucial role in the transport of host messenger RNA (mRNA). Nsp1 interferes with the proper binding of NXF1 to mRNA export adaptors and its docking to the nuclear pore complex. We propose that drugs targeting the binding surface between Nsp1 and NXF1-NXT1 may be a useful strategy to restore host antiviral gene expression. Exploring this strategy forms the main goals of this paper. Crystal structures of Nsp1 and the heterodimer of NXF1-NXT1 have been determined. We modeled the docking of Nsp1 to the NXF1-NXT1 complex, and discovered repurposed drugs that may interfere with this binding. To our knowledge, this is the first attempt at drug-repurposing of this complex. We used structural analysis to screen 1993 FDA-approved drugs for docking to the NXF1-NXT1 complex. The top hit was ganirelix, with a docking score of -14.49. Ganirelix competitively antagonizes the gonadotropin releasing hormone receptor (GNRHR) on pituitary gonadotrophs, and induces rapid, reversible suppression of gonadotropin secretion. The conformations of Nsp1 and GNRHR make it unlikely that they interact with each other. Additional drug leads were inferred from the structural analysis of this complex, which are discussed in the paper. These drugs offer several options for therapeutically blocking Nsp1 binding to NFX1-NXT1, which may normalize nuclear export in COVID-19 infection.
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Affiliation(s)
- Sona Vasudevan
- Department of Biochemistry, Molecular and Cellular Biology, Georgetown University Medical Center, 3900 Reservoir Road NW, Washington, DC 20057, USA
| | - James N Baraniuk
- Division of Rheumatology, Immunology and Allergy, Department of Medicine, Georgetown University Medical Center, 3900 Reservoir Road NW, Washington, DC 20007, USA
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30
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Padilla-Mejia NE, Makarov AA, Barlow LD, Butterfield ER, Field MC. Evolution and diversification of the nuclear envelope. Nucleus 2021; 12:21-41. [PMID: 33435791 PMCID: PMC7889174 DOI: 10.1080/19491034.2021.1874135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic cells arose ~1.5 billion years ago, with the endomembrane system a central feature, facilitating evolution of intracellular compartments. Endomembranes include the nuclear envelope (NE) dividing the cytoplasm and nucleoplasm. The NE possesses universal features: a double lipid bilayer membrane, nuclear pore complexes (NPCs), and continuity with the endoplasmic reticulum, indicating common evolutionary origin. However, levels of specialization between lineages remains unclear, despite distinct mechanisms underpinning various nuclear activities. Several distinct modes of molecular evolution facilitate organellar diversification and to understand which apply to the NE, we exploited proteomic datasets of purified nuclear envelopes from model systems for comparative analysis. We find enrichment of core nuclear functions amongst the widely conserved proteins to be less numerous than lineage-specific cohorts, but enriched in core nuclear functions. This, together with consideration of additional evidence, suggests that, despite a common origin, the NE has evolved as a highly diverse organelle with significant lineage-specific functionality.
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Affiliation(s)
- Norma E. Padilla-Mejia
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Alexandr A. Makarov
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Lael D. Barlow
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Erin R. Butterfield
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
| | - Mark C. Field
- Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, UK
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České, Czech Republic
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31
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De Magistris P. The Great Escape: mRNA Export through the Nuclear Pore Complex. Int J Mol Sci 2021; 22:ijms222111767. [PMID: 34769195 PMCID: PMC8583845 DOI: 10.3390/ijms222111767] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/18/2021] [Accepted: 10/21/2021] [Indexed: 12/30/2022] Open
Abstract
Nuclear export of messenger RNA (mRNA) through the nuclear pore complex (NPC) is an indispensable step to ensure protein translation in the cytoplasm of eukaryotic cells. mRNA is not translocated on its own, but it forms ribonuclear particles (mRNPs) in association with proteins that are crucial for its metabolism, some of which; like Mex67/MTR2-NXF1/NXT1; are key players for its translocation to the cytoplasm. In this review, I will summarize our current body of knowledge on the basic characteristics of mRNA export through the NPC. To be granted passage, the mRNP cargo needs to bind transport receptors, which facilitate the nuclear export. During NPC transport, mRNPs undergo compositional and conformational changes. The interactions between mRNP and the central channel of NPC are described; together with the multiple quality control steps that mRNPs undergo at the different rings of the NPC to ensure only proper export of mature transcripts to the cytoplasm. I conclude by mentioning new opportunities that arise from bottom up approaches for a mechanistic understanding of nuclear export.
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32
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Niikura M, Fukutomi T, Mitobe J, Kobayashi F. Roles and Cellular Localization of GBP2 and NAB2 During the Blood Stage of Malaria Parasites. Front Cell Infect Microbiol 2021; 11:737457. [PMID: 34604117 PMCID: PMC8479154 DOI: 10.3389/fcimb.2021.737457] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/24/2021] [Indexed: 12/03/2022] Open
Abstract
The quality control and export of mRNA by RNA-binding proteins are necessary for the survival of malaria parasites, which have complex life cycles. Nuclear poly(A) binding protein 2 (NAB2), THO complex subunit 4 (THO4), nucleolar protein 3 (NPL3), G-strand binding protein 2 (GBP2) and serine/arginine-rich splicing factor 1 (SR1) are involved in nuclear mRNA export in malaria parasites. However, their roles in asexual and sexual development, and in cellular localization, are not fully understood. In this study using the rodent malaria parasite, Plasmodium berghei, we found that NAB2 and SR1, but not THO4, NPL3 or GBP2, played essential roles in the asexual development of malaria parasites. By contrast, GBP2 but not NPL3 was involved in male and female gametocyte production. THO4 was involved in female gametocyte production, but had a lower impact than GBP2. In this study, we focused on GBP2 and NAB2, which play important roles in the sexual and asexual development of malaria parasites, respectively, and examined their cellular localization. GBP2 localized to both the nucleus and cytoplasm of malaria parasites. Using immunoprecipitation coupled to mass spectrometry (IP-MS), GBP2 interacted with the proteins ALBA4, DOZI, and CITH, which play roles in translational repression. IP-MS also revealed that phosphorylated adapter RNA export protein (PHAX) domain-containing protein, an adaptor protein for exportin-1, also interacted with GBP2, implying that mRNA export occurs via the PHAX domain-containing protein pathway in malaria parasites. Live-cell fluorescence imaging revealed that NAB2 localized at the nuclear periphery. Moreover, IP-MS indicated that NAB2 interacted with transportin. RNA immunoprecipitation coupled to RNA sequencing revealed that NAB2 bound directly to 143 mRNAs, including those encoding 40S and 60S ribosomal proteins. Our findings imply that malaria parasites use an evolutionarily ancient mechanism conserved throughout eukaryotic evolution.
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Affiliation(s)
- Mamoru Niikura
- Department of Infectious Diseases, Kyorin University School of Medicine, Tokyo, Japan
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Jiro Mitobe
- Department of Infectious Diseases, Kyorin University School of Medicine, Tokyo, Japan
| | - Fumie Kobayashi
- Department of Environmental Science, School of Life and Environmental Science, Azabu University, Kanagawa, Japan
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33
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Sajidah ES, Lim K, Wong RW. How SARS-CoV-2 and Other Viruses Build an Invasion Route to Hijack the Host Nucleocytoplasmic Trafficking System. Cells 2021; 10:1424. [PMID: 34200500 PMCID: PMC8230057 DOI: 10.3390/cells10061424] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/31/2021] [Accepted: 06/03/2021] [Indexed: 12/14/2022] Open
Abstract
The host nucleocytoplasmic trafficking system is often hijacked by viruses to accomplish their replication and to suppress the host immune response. Viruses encode many factors that interact with the host nuclear transport receptors (NTRs) and the nucleoporins of the nuclear pore complex (NPC) to access the host nucleus. In this review, we discuss the viral factors and the host factors involved in the nuclear import and export of viral components. As nucleocytoplasmic shuttling is vital for the replication of many viruses, we also review several drugs that target the host nuclear transport machinery and discuss their feasibility for use in antiviral treatment.
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Affiliation(s)
- Elma Sakinatus Sajidah
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan;
| | - Keesiang Lim
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
| | - Richard W. Wong
- Division of Nano Life Science in the Graduate School of Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan;
- WPI-Nano Life Science Institute, Kanazawa University, Kanazawa 920-1192, Japan
- Cell-Bionomics Research Unit, Institute for Frontier Science Initiative, Kanazawa University, Kanazawa 920-1192, Japan
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34
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Bensidoun P, Zenklusen D, Oeffinger M. Choosing the right exit: How functional plasticity of the nuclear pore drives selective and efficient mRNA export. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1660. [PMID: 33938148 DOI: 10.1002/wrna.1660] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/30/2021] [Accepted: 04/04/2021] [Indexed: 12/17/2022]
Abstract
The nuclear pore complex (NPC) serves as a central gate for mRNAs to transit from the nucleus to the cytoplasm. The ability for mRNAs to get exported is linked to various upstream nuclear processes including co-transcriptional RNP assembly and processing, and only export competent mRNPs are thought to get access to the NPC. While the nuclear pore is generally viewed as a monolithic structure that serves as a mediator of transport driven by transport receptors, more recent evidence suggests that the NPC might be more heterogenous than previously believed, both in its composition or in the selective treatment of cargo that seek access to the pore, providing functional plasticity to mRNA export. In this review, we consider the interconnected processes of nuclear mRNA metabolism that contribute and mediate export competence. Furthermore, we examine different aspects of NPC heterogeneity, including the role of the nuclear basket and its associated complexes in regulating selective and/or efficient binding to and transport through the pore. This article is categorized under: RNA Export and Localization > Nuclear Export/Import RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Pierre Bensidoun
- Systems Biology, Institut de Recherches Cliniques de Montréal, Montréal, Canada.,Département de Biochimie et Médecine Moléculaire, Faculté de médecine, Université de Montréal, Montréal, Canada
| | - Daniel Zenklusen
- Département de Biochimie et Médecine Moléculaire, Faculté de médecine, Université de Montréal, Montréal, Canada
| | - Marlene Oeffinger
- Systems Biology, Institut de Recherches Cliniques de Montréal, Montréal, Canada.,Département de Biochimie et Médecine Moléculaire, Faculté de médecine, Université de Montréal, Montréal, Canada.,Faculty of Medicine, Division of Experimental Medicine, McGill University, Montréal, Canada
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35
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Ding B, Sepehrimanesh M. Nucleocytoplasmic Transport: Regulatory Mechanisms and the Implications in Neurodegeneration. Int J Mol Sci 2021; 22:4165. [PMID: 33920577 PMCID: PMC8072611 DOI: 10.3390/ijms22084165] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 12/12/2022] Open
Abstract
Nucleocytoplasmic transport (NCT) across the nuclear envelope is precisely regulated in eukaryotic cells, and it plays critical roles in maintenance of cellular homeostasis. Accumulating evidence has demonstrated that dysregulations of NCT are implicated in aging and age-related neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer's disease (AD), and Huntington disease (HD). This is an emerging research field. The molecular mechanisms underlying impaired NCT and the pathogenesis leading to neurodegeneration are not clear. In this review, we comprehensively described the components of NCT machinery, including nuclear envelope (NE), nuclear pore complex (NPC), importins and exportins, RanGTPase and its regulators, and the regulatory mechanisms of nuclear transport of both protein and transcript cargos. Additionally, we discussed the possible molecular mechanisms of impaired NCT underlying aging and neurodegenerative diseases, such as ALS/FTD, HD, and AD.
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Affiliation(s)
- Baojin Ding
- Department of Biology, University of Louisiana at Lafayette, 410 East Saint Mary Boulevard, Lafayette, LA 70503, USA;
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36
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Xie Y, Clarke BP, Kim YJ, Ivey AL, Hill PS, Shi Y, Ren Y. Cryo-EM structure of the yeast TREX complex and coordination with the SR-like protein Gbp2. eLife 2021; 10:e65699. [PMID: 33787496 PMCID: PMC8043747 DOI: 10.7554/elife.65699] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 03/30/2021] [Indexed: 12/21/2022] Open
Abstract
The evolutionarily conserved TRanscript-EXport (TREX) complex plays central roles during mRNP (messenger ribonucleoprotein) maturation and export from the nucleus to the cytoplasm. In yeast, TREX is composed of the THO sub-complex (Tho2, Hpr1, Tex1, Mft1, and Thp2), the DEAD box ATPase Sub2, and Yra1. Here we present a 3.7 Å cryo-EM structure of the yeast THO•Sub2 complex. The structure reveals the intimate assembly of THO revolving around its largest subunit Tho2. THO stabilizes a semi-open conformation of the Sub2 ATPase via interactions with Tho2. We show that THO interacts with the serine-arginine (SR)-like protein Gbp2 through both the RS domain and RRM domains of Gbp2. Cross-linking mass spectrometry analysis supports the extensive interactions between THO and Gbp2, further revealing that RRM domains of Gbp2 are in close proximity to the C-terminal domain of Tho2. We propose that THO serves as a landing pad to configure Gbp2 to facilitate its loading onto mRNP.
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Affiliation(s)
- Yihu Xie
- Department of Biochemistry, Vanderbilt University School of MedicineNashvilleUnited States
| | - Bradley P Clarke
- Department of Biochemistry, Vanderbilt University School of MedicineNashvilleUnited States
| | - Yong Joon Kim
- Department of Cell Biology, University of PittsburghPittsburghUnited States
- Medical Scientist Training Program, University of Pittsburgh and Carnegie Mellon UniversityPittsburghUnited States
| | - Austin L Ivey
- Department of Biochemistry, Vanderbilt University School of MedicineNashvilleUnited States
| | - Pate S Hill
- Department of Biochemistry, Vanderbilt University School of MedicineNashvilleUnited States
| | - Yi Shi
- Department of Cell Biology, University of PittsburghPittsburghUnited States
- Medical Scientist Training Program, University of Pittsburgh and Carnegie Mellon UniversityPittsburghUnited States
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University School of MedicineNashvilleUnited States
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37
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Hachiya N, Sochocka M, Brzecka A, Shimizu T, Gąsiorowski K, Szczechowiak K, Leszek J. Nuclear Envelope and Nuclear Pore Complexes in Neurodegenerative Diseases-New Perspectives for Therapeutic Interventions. Mol Neurobiol 2021; 58:983-995. [PMID: 33067781 PMCID: PMC7878205 DOI: 10.1007/s12035-020-02168-x] [Citation(s) in RCA: 12] [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: 05/27/2020] [Accepted: 10/12/2020] [Indexed: 12/11/2022]
Abstract
Transport of proteins, transcription factors, and other signaling molecules between the nucleus and cytoplasm is necessary for signal transduction. The study of these transport phenomena is particularly challenging in neurons because of their highly polarized structure. The bidirectional exchange of molecular cargoes across the nuclear envelope (NE) occurs through nuclear pore complexes (NPCs), which are aqueous channels embedded in the nuclear envelope. The NE and NPCs regulate nuclear transport but are also emerging as relevant regulators of chromatin organization and gene expression. The alterations in nuclear transport are regularly identified in affected neurons associated with human neurodegenerative diseases. This review presents insights into the roles played by nuclear transport defects in neurodegenerative disease, focusing primarily on NE proteins and NPCs. The subcellular mislocalization of proteins might be a very desirable means of therapeutic intervention in neurodegenerative disorders.
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Affiliation(s)
- Naomi Hachiya
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
| | - Marta Sochocka
- Laboratory of Virology, Department of Immunology of Infectious Diseases, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Anna Brzecka
- Department of Pulmonology and Lung Cancer, Wroclaw Medical University, Wroclaw, Poland
| | - Takuto Shimizu
- Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, Japan
- Laboratory of Biochemistry, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | | | | | - Jerzy Leszek
- Department of Psychiatry, Wroclaw Medical University, Wybrzeże L. Pasteura 10, 50-367, Wroclaw, Poland.
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38
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Glukhova AA, Kurshakova MM, Nabirochkina EN, Georgieva SG, Kopytova DV. PCID2, a subunit of the Drosophila TREX-2 nuclear export complex, is essential for both mRNA nuclear export and its subsequent cytoplasmic trafficking. RNA Biol 2021; 18:1969-1980. [PMID: 33602059 DOI: 10.1080/15476286.2021.1885198] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The TREX-2 complex is essential for the general nuclear mRNA export in eukaryotes. TREX-2 interacts with the nuclear pore and transcriptional apparatus and links transcription to the mRNA export. However, it remains poorly understood how the TREX-2-dependent nuclear export is connected to the subsequent stages of mRNA trafficking. Here, we show that the PCID2 subunit of Drosophila TREX-2 is present in the cytoplasm of the cell. The cytoplasmic PCID2 directly interacts with the NudC protein and this interaction maintains its stability in the cytoplasm. Moreover, PCID2 is associated with the cytoplasmic mRNA and microtubules. The PCID2 knockdown blocks nuclear export of mRNA and also affects the general mRNA transport into the cytoplasm. These data suggest that PCID2 could be the link between the nuclear TREX-2-dependent export and the subsequent cytoplasmic trafficking of mRNA.
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Affiliation(s)
- A A Glukhova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - M M Kurshakova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - E N Nabirochkina
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - S G Georgieva
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.,Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - D V Kopytova
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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39
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One Ring to Rule them All? Structural and Functional Diversity in the Nuclear Pore Complex. Trends Biochem Sci 2021; 46:595-607. [PMID: 33563541 DOI: 10.1016/j.tibs.2021.01.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 02/07/2023]
Abstract
The nuclear pore complex (NPC) is the massive protein assembly that regulates the transport of macromolecules between the nucleus and the cytoplasm. Recent breakthroughs have provided major insights into the structure of the NPC in different eukaryotes, revealing a previously unsuspected diversity of NPC architectures. In parallel, the NPC has been shown to be a key player in regulating essential nuclear processes such as chromatin organization, gene expression, and DNA repair. However, our knowledge of the NPC structure has not been able to address the molecular mechanisms underlying its regulatory roles. We discuss potential explanations, including the coexistence of alternative NPC architectures with specific functional roles.
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40
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Zhang K, Miorin L, Makio T, Dehghan I, Gao S, Xie Y, Zhong H, Esparza M, Kehrer T, Kumar A, Hobman TC, Ptak C, Gao B, Minna JD, Chen Z, García-Sastre A, Ren Y, Wozniak RW, Fontoura BMA. Nsp1 protein of SARS-CoV-2 disrupts the mRNA export machinery to inhibit host gene expression. SCIENCE ADVANCES 2021; 7:7/6/eabe7386. [PMID: 33547084 PMCID: PMC7864571 DOI: 10.1126/sciadv.abe7386] [Citation(s) in RCA: 124] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 12/16/2020] [Indexed: 05/04/2023]
Abstract
The ongoing unprecedented severe acute respiratory syndrome caused by the SARS-CoV-2 outbreak worldwide has highlighted the need for understanding viral-host interactions involved in mechanisms of virulence. Here, we show that the virulence factor Nsp1 protein of SARS-CoV-2 interacts with the host messenger RNA (mRNA) export receptor heterodimer NXF1-NXT1, which is responsible for nuclear export of cellular mRNAs. Nsp1 prevents proper binding of NXF1 to mRNA export adaptors and NXF1 docking at the nuclear pore complex. As a result, a significant number of cellular mRNAs are retained in the nucleus during infection. Increased levels of NXF1 rescues the Nsp1-mediated mRNA export block and inhibits SARS-CoV-2 infection. Thus, antagonizing the Nsp1 inhibitory function on mRNA export may represent a strategy to restoring proper antiviral host gene expression in infected cells.
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Affiliation(s)
- Ke Zhang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lisa Miorin
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Tadashi Makio
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ishmael Dehghan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shengyan Gao
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yihu Xie
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37235, USA
| | - Hualin Zhong
- Department of Biological Sciences, Hunter College, New York, NY 10065, USA
| | - Matthew Esparza
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Thomas Kehrer
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Anil Kumar
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Tom C Hobman
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Christopher Ptak
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Boning Gao
- Nancy B. and Jake L. Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - John D Minna
- Nancy B. and Jake L. Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Departments of Internal Medicine and Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Zhijian Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Adolfo García-Sastre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Global Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- Department of Medicine, Division of Infectious Diseases, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
- The Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37235, USA
| | - Richard W Wozniak
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Beatriz M A Fontoura
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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41
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Structure and activation mechanism of the yeast RNA Pol II CTD kinase CTDK-1 complex. Proc Natl Acad Sci U S A 2021; 118:2019163118. [PMID: 33431688 DOI: 10.1073/pnas.2019163118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The C-terminal domain (CTD) kinase I (CTDK-1) complex is the primary RNA Polymerase II (Pol II) CTD Ser2 kinase in budding yeast. CTDK-1 consists of a cyclin-dependent kinase (CDK) Ctk1, a cyclin Ctk2, and a unique subunit Ctk3 required for CTDK-1 activity. Here, we present a crystal structure of CTDK-1 at 1.85-Å resolution. The structure reveals that, compared to the canonical two-component CDK-cyclin system, the third component Ctk3 of CTDK-1 plays a critical role in Ctk1 activation by stabilizing a key element of CDK regulation, the T-loop, in an active conformation. In addition, Ctk3 contributes to the assembly of CTDK-1 through extensive interactions with both Ctk1 and Ctk2. We also demonstrate that CTDK-1 physically and genetically interacts with the serine/arginine-like protein Gbp2. Together, the data in our work reveal a regulatory mechanism of CDK complexes.
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42
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van der Graaf K, Jindrich K, Mitchell R, White-Cooper H. Roles for RNA export factor, Nxt1, in ensuring muscle integrity and normal RNA expression in Drosophila. G3-GENES GENOMES GENETICS 2021; 11:6046993. [PMID: 33561245 PMCID: PMC8022728 DOI: 10.1093/g3journal/jkaa046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/10/2020] [Indexed: 11/15/2022]
Abstract
The mRNA export pathway is responsible for the transport of mRNAs from the nucleus to the cytoplasm, and thus is essential for protein production and normal cellular functions. A partial loss of function allele of the mRNA export factor Nxt1 in Drosophila shows reduced viability and sterility. A previous study has shown that the male fertility defect is due to a defect in transcription and RNA stability, indicating the potential for this pathway to be implicated in processes beyond the known mRNA transport function. Here we investigate the reduced viability of Nxt1 partial loss of function mutants, and describe a defect in growth and maintenance of the larval muscles, leading to muscle degeneration. RNA-seq revealed reduced expression of a set of mRNAs, particularly from genes with long introns in Nxt1 mutant carcass. We detected differential expression of circRNA, and significantly fewer distinct circRNAs expressed in the mutants. Despite the widespread defects in gene expression, muscle degeneration was rescued by increased expression of the costamere component tn (abba) in muscles. This is the first report of a role for the RNA export pathway gene Nxt1 in the maintenance of muscle integrity. Our data also links the mRNA export pathway to a specific role in the expression of mRNA and circRNA from common precursor genes, in vivo.
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Affiliation(s)
| | - Katia Jindrich
- School of Biosciences, Cardiff University, Cardiff CF10 3AT, UK
| | - Robert Mitchell
- School of Biosciences, Cardiff University, Cardiff CF10 3AT, UK
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43
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Mason AC, Wente SR. Functions of Gle1 are governed by two distinct modes of self-association. J Biol Chem 2020; 295:16813-16825. [PMID: 32981894 PMCID: PMC7864074 DOI: 10.1074/jbc.ra120.015715] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/23/2020] [Indexed: 11/08/2022] Open
Abstract
Gle1 is a conserved, essential regulator of DEAD-box RNA helicases, with critical roles defined in mRNA export, translation initiation, translation termination, and stress granule formation. Mechanisms that specify which, where, and when DDXs are targeted by Gle1 are critical to understand. In addition to roles for stress-induced phosphorylation and inositol hexakisphosphate binding in specifying Gle1 function, Gle1 oligomerizes via its N-terminal domain in a phosphorylation-dependent manner. However, a thorough analysis of the role for Gle1 self-association is lacking. Here, we find that Gle1 self-association is driven by two distinct regions: a coiled-coil domain and a novel 10-amino acid aggregation-prone region, both of which are necessary for proper Gle1 oligomerization. By exogenous expression in HeLa cells, we tested the function of a series of mutations that impact the oligomerization domains of the Gle1A and Gle1B isoforms. Gle1 oligomerization is necessary for many, but not all aspects of Gle1A and Gle1B function, and the requirements for each interaction domain differ. Whereas the coiled-coil domain and aggregation-prone region additively contribute to competent mRNA export and stress granule formation, both self-association domains are independently required for regulation of translation under cellular stress. In contrast, Gle1 self-association is dispensable for phosphorylation and nonstressed translation initiation. Collectively, we reveal self-association functions as an additional mode of Gle1 regulation to ensure proper mRNA export and translation. This work also provides further insight into the mechanisms underlying human gle1 disease mutants found in prenatally lethal forms of arthrogryposis.
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Affiliation(s)
- Aaron C Mason
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Susan R Wente
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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44
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Schuller SK, Schuller JM, Prabu JR, Baumgärtner M, Bonneau F, Basquin J, Conti E. Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex. eLife 2020; 9:e61467. [PMID: 33191913 PMCID: PMC7744097 DOI: 10.7554/elife.61467] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/13/2020] [Indexed: 12/15/2022] Open
Abstract
The yeast THO complex is recruited to active genes and interacts with the RNA-dependent ATPase Sub2 to facilitate the formation of mature export-competent messenger ribonucleoprotein particles and to prevent the co-transcriptional formation of RNA:DNA-hybrid-containing structures. How THO-containing complexes function at the mechanistic level is unclear. Here, we elucidated a 3.4 Å resolution structure of Saccharomyces cerevisiae THO-Sub2 by cryo-electron microscopy. THO subunits Tho2 and Hpr1 intertwine to form a platform that is bound by Mft1, Thp2, and Tex1. The resulting complex homodimerizes in an asymmetric fashion, with a Sub2 molecule attached to each protomer. The homodimerization interfaces serve as a fulcrum for a seesaw-like movement concomitant with conformational changes of the Sub2 ATPase. The overall structural architecture and topology suggest the molecular mechanisms of nucleic acid remodeling during mRNA biogenesis.
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Affiliation(s)
- Sandra K Schuller
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - Jan M Schuller
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - J Rajan Prabu
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - Marc Baumgärtner
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - Fabien Bonneau
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - Jérôme Basquin
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
| | - Elena Conti
- Department of Structural Cell Biology, Max Planck Institute of BiochemistryMunichGermany
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45
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Pühringer T, Hohmann U, Fin L, Pacheco-Fiallos B, Schellhaas U, Brennecke J, Plaschka C. Structure of the human core transcription-export complex reveals a hub for multivalent interactions. eLife 2020; 9:e61503. [PMID: 33191911 PMCID: PMC7744094 DOI: 10.7554/elife.61503] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/13/2020] [Indexed: 12/24/2022] Open
Abstract
The export of mRNA from nucleus to cytoplasm requires the conserved and essential transcription and export (TREX) complex (THO-UAP56/DDX39B-ALYREF). TREX selectively binds mRNA maturation marks and licenses mRNA for nuclear export by loading the export factor NXF1-NXT1. How TREX integrates these marks and achieves high selectivity for mature mRNA is poorly understood. Here, we report the cryo-electron microscopy structure of the human THO-UAP56/DDX39B complex at 3.3 Å resolution. The seven-subunit THO-UAP56/DDX39B complex multimerizes into a 28-subunit tetrameric assembly, suggesting that selective recognition of mature mRNA is facilitated by the simultaneous sensing of multiple, spatially distant mRNA regions and maturation marks. Two UAP56/DDX39B RNA helicases are juxtaposed at each end of the tetramer, which would allow one bivalent ALYREF protein to bridge adjacent helicases and regulate the TREX-mRNA interaction. Our structural and biochemical results suggest a conserved model for TREX complex function that depends on multivalent interactions between proteins and mRNA.
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Affiliation(s)
- Thomas Pühringer
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
| | - Ulrich Hohmann
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)ViennaAustria
| | - Laura Fin
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
| | - Belén Pacheco-Fiallos
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
| | - Ulla Schellhaas
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
| | - Julius Brennecke
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA)ViennaAustria
| | - Clemens Plaschka
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC)ViennaAustria
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46
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Kozlova I, Sah S, Keable R, Leshchyns'ka I, Janitz M, Sytnyk V. Cell Adhesion Molecules and Protein Synthesis Regulation in Neurons. Front Mol Neurosci 2020; 13:592126. [PMID: 33281551 PMCID: PMC7689008 DOI: 10.3389/fnmol.2020.592126] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 10/16/2020] [Indexed: 12/18/2022] Open
Abstract
Cell adhesion molecules (CAMs) mediate interactions of neurons with the extracellular environment by forming adhesive bonds with CAMs on adjacent membranes or via binding to proteins of the extracellular matrix. Binding of CAMs to their extracellular ligands results in the activation of intracellular signaling cascades, leading to changes in neuronal structure and the molecular composition and function of neuronal contacts. Ultimately, many of these changes depend on the synthesis of new proteins. In this review, we summarize the evidence showing that CAMs regulate protein synthesis by modulating the activity of transcription factors, gene expression, protein translation, and the structure and distribution of organelles involved in protein synthesis and transport.
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Affiliation(s)
- Irina Kozlova
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Saroj Sah
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Ryan Keable
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Iryna Leshchyns'ka
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Michael Janitz
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Vladimir Sytnyk
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
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47
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Gallardo P, Real-Calderón P, Flor-Parra I, Salas-Pino S, Daga RR. Acute Heat Stress Leads to Reversible Aggregation of Nuclear Proteins into Nucleolar Rings in Fission Yeast. Cell Rep 2020; 33:108377. [DOI: 10.1016/j.celrep.2020.108377] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Revised: 08/24/2020] [Accepted: 10/21/2020] [Indexed: 12/15/2022] Open
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Subcellular Localization of MxB Determines Its Antiviral Potential against Influenza A Virus. J Virol 2020; 94:JVI.00125-20. [PMID: 32907985 PMCID: PMC7592211 DOI: 10.1128/jvi.00125-20] [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: 01/23/2020] [Accepted: 09/01/2020] [Indexed: 11/20/2022] Open
Abstract
The interferon system plays a pivotal role in the defense against viral infections. The dynamin-related Mx proteins form a small family of interferon-induced effector proteins with distinct antiviral specificities and subcellular localizations. So far, it is not clear whether the different virus specificities of Mx proteins are the result of distinct mechanisms of action or are due rather to their different subcellular localization. We show here that the human MxB protein, normally localized to the outer membrane of the cell nucleus, acquires antiviral activity against IAV when redirected to the nucleus or cytoplasm, subcellular sites where other members of the Mx protein family efficiently interfere with IAV replication. Our findings thus strongly suggest that Mx proteins act primarily through a common mechanism and that their viral specificity is at least in part determined by their individual subcellular localization. Mx proteins are interferon (IFN) type I (α/β)- and type III (λ)-induced effector proteins with intrinsic antiviral activity. Mammalian Mx proteins show different subcellular localizations and distinct yet partially overlapping viral specificities. However, the precise mechanism(s) of antiviral action are still unresolved. Human MxA accumulates in the cytoplasm and inhibits a wide variety of RNA and DNA viruses, among them influenza A virus (IAV). In contrast, MxB, the second human Mx protein, localizes via its amino (N) terminus to the outer nuclear membrane at or near nuclear pores and inhibits the nuclear import of incoming human immunodeficiency viruses (HIV) and herpesviruses, but not that of IAV. Here, we evaluated whether the antiviral specificity of MxB is determined by its subcellular localization. For this purpose, we redirected MxB to the nucleus or cytoplasm by either attaching a nuclear localization signal to its N terminus or by exchanging the N terminus of MxB with that of MxA. Interestingly, ectopic expression of these MxB variants in the nucleus or in the cytoplasm rendered the host cells resistant to IAV, revealing that the capacity of MxB to block IAV replication critically depends on the site where the protein accumulates in the infected cell. Furthermore, coimmunoprecipitation (co-IP) assays demonstrated that MxB physically interacted with the nucleoprotein (NP) of IAV. Taken together, the data indicate that the subcellular localization of the MxB protein plays a pivotal role in determining its antiviral specificity. IMPORTANCE The interferon system plays a pivotal role in the defense against viral infections. The dynamin-related Mx proteins form a small family of interferon-induced effector proteins with distinct antiviral specificities and subcellular localizations. So far, it is not clear whether the different virus specificities of Mx proteins are the result of distinct mechanisms of action or are due rather to their different subcellular localization. We show here that the human MxB protein, normally localized to the outer membrane of the cell nucleus, acquires antiviral activity against IAV when redirected to the nucleus or cytoplasm, subcellular sites where other members of the Mx protein family efficiently interfere with IAV replication. Our findings thus strongly suggest that Mx proteins act primarily through a common mechanism and that their viral specificity is at least in part determined by their individual subcellular localization.
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Briata P, Gherzi R. Long Non-Coding RNA-Ribonucleoprotein Networks in the Post-Transcriptional Control of Gene Expression. Noncoding RNA 2020; 6:ncrna6030040. [PMID: 32957640 PMCID: PMC7549350 DOI: 10.3390/ncrna6030040] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/10/2020] [Accepted: 09/16/2020] [Indexed: 12/18/2022] Open
Abstract
Although mammals possess roughly the same number of protein-coding genes as worms, it is evident that the non-coding transcriptome content has become far broader and more sophisticated during evolution. Indeed, the vital regulatory importance of both short and long non-coding RNAs (lncRNAs) has been demonstrated during the last two decades. RNA binding proteins (RBPs) represent approximately 7.5% of all proteins and regulate the fate and function of a huge number of transcripts thus contributing to ensure cellular homeostasis. Transcriptomic and proteomic studies revealed that RBP-based complexes often include lncRNAs. This review will describe examples of how lncRNA-RBP networks can virtually control all the post-transcriptional events in the cell.
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Sharma M, Wente SR. Nucleocytoplasmic shuttling of Gle1 impacts DDX1 at transcription termination sites. Mol Biol Cell 2020; 31:2398-2408. [PMID: 32755435 PMCID: PMC7851961 DOI: 10.1091/mbc.e20-03-0215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Gle1 is a nucleocytoplasmic shuttling protein with well-documented cytoplasmic roles as a modulator of ATP-dependent DEAD-box RNA helicases involved in messenger (m)RNA export, translation initiation and termination, and stress granule dynamics. Here, we identify a novel nuclear role for Gle1 during transcription termination. In HeLa cells treated with a peptide that disrupts Gle1 nucleocytoplasmic shuttling, we detected nuclear accumulation of specific mRNAs with elongated 3′-UTR (untranslated region). Enriched mRNAs were nascently transcribed and accumulated in the nucleus due to a change in transcription state and not due to altered nuclear export. Whereas Gle1 shuttling inhibition did not appear to perturb nuclear DDX19 functions, it did result in increased DDX1 nucleoplasmic localization and decreased DDX1 interactions with Gle1 and the pre-mRNA cleavage stimulation factor CstF-64. An increase in nuclear R-loop signal intensity was also observed with diminished Gle1 shuttling, as well as colocalization of Gle1 at R-loops. Taken together, these studies reveal a nuclear role for Gle1 in coordinating DDX1 function in transcription termination complexes.
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Affiliation(s)
- Manisha Sharma
- Department of Cell and Developmental Biology, School of Medicine, Vanderbilt University, Nashville, TN 37240
| | - Susan R Wente
- Department of Cell and Developmental Biology, School of Medicine, Vanderbilt University, Nashville, TN 37240
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