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Roesmann F, Sertznig H, Klaassen K, Wilhelm A, Heininger D, Heß S, Elsner C, Marschalek R, Santiago ML, Esser S, Sutter K, Dittmer U, Widera M. The interferon-regulated host factor hnRNPA0 modulates HIV-1 production by interference with LTR activity, mRNA trafficking, and programmed ribosomal frameshifting. J Virol 2024; 98:e0053424. [PMID: 38899932 PMCID: PMC11265465 DOI: 10.1128/jvi.00534-24] [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: 03/23/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
The interplay between host factors and viral components impacts viral replication efficiency profoundly. Members of the cellular heterogeneous nuclear ribonucleoprotein family (hnRNPs) have been extensively studied as HIV-1 host dependency factors, but whether they play a role in innate immunity is currently unknown. This study aimed to identify hnRNPA0 as a type I interferon (IFN)-repressed host factor in HIV-1-infected cells. Knockdown of hnRNPA0, a situation that mirrors conditions under IFN stimulation, increased LTR activity, export of unspliced HIV-1 mRNA, viral particle production, and thus, increased infectivity. Conversely, hnRNPA0 overexpression primarily reduced plasmid-driven and integrated HIV-1 long terminal repeat (LTR) activity, significantly decreasing total viral mRNA and protein levels. In addition, high levels of hnRNPA0 significantly reduced the HIV-1 programmed ribosomal frameshifting efficiency, resulting in a shift in the HIV-1 p55/p15 ratio. The HIV-1 alternative splice site usage remained largely unaffected by altered hnRNPA0 levels suggesting that the synergistic inhibition of the LTR activity and viral mRNA transcription, as well as impaired ribosomal frameshifting efficiency, are critical factors for efficient HIV-1 replication regulated by hnRNPA0. The pleiotropic dose-dependent effects under high or low hnRNPA0 levels were further confirmed in HIV-1-infected Jurkat cells. Finally, our study revealed that hnRNPA0 levels in PBMCs were lower in therapy-naive HIV-1-infected individuals compared to healthy controls. Our findings highlight a significant role for hnRNPA0 in HIV-1 replication and suggest that its IFN-I-regulated expression levels are critical for viral fitness allowing replication in an antiviral environment.IMPORTANCERNA-binding proteins, in particular, heterogeneous nuclear ribonucleoproteins (hnRNPs), have been extensively studied. Some act as host dependency factors for HIV-1 since they are involved in multiple cellular gene expression processes. Our study revealed hnRNPA0 as an IFN-regulated host factor, that is differently expressed after IFN-I treatment in HIV-1 target cells and lower expressed in therapy-naïve HIV-1-infected individuals. Our findings demonstrate the significant pleiotropic role of hnRNPA0 in viral replication: In high concentrations, hnRNPA0 limits viral replication by negatively regulating Tat-LTR transcription, retaining unspliced mRNA in the nucleus, and significantly impairing programmed ribosomal frameshifting. Low hnRNPA0 levels as observed in IFN-treated THP-1 cells, particularly facilitate HIV LTR activity and unspliced mRNA export, suggesting a role in innate immunity in favor of HIV replication. Understanding the mode of action between hnRNPA0 and HIV-1 gene expression might help to identify novel therapeutically strategies against HIV-1 and other viruses.
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Affiliation(s)
- Fabian Roesmann
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Helene Sertznig
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Katleen Klaassen
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Alexander Wilhelm
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Delia Heininger
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Stefanie Heß
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Carina Elsner
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Rolf Marschalek
- Institute of Pharmaceutical Biology, Goethe-University, Frankfurt am Main, Hessen, Germany
| | - Mario L. Santiago
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, USA
| | - Stefan Esser
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Department of Dermatology, HPSTD Outpatient Clinic, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Kathrin Sutter
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ulf Dittmer
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Marek Widera
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
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Roesmann F, Müller L, Klaassen K, Heß S, Widera M. Interferon-Regulated Expression of Cellular Splicing Factors Modulates Multiple Levels of HIV-1 Gene Expression and Replication. Viruses 2024; 16:938. [PMID: 38932230 PMCID: PMC11209495 DOI: 10.3390/v16060938] [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: 04/30/2024] [Revised: 05/31/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024] Open
Abstract
Type I interferons (IFN-Is) are pivotal in innate immunity against human immunodeficiency virus I (HIV-1) by eliciting the expression of IFN-stimulated genes (ISGs), which encompass potent host restriction factors. While ISGs restrict the viral replication within the host cell by targeting various stages of the viral life cycle, the lesser-known IFN-repressed genes (IRepGs), including RNA-binding proteins (RBPs), affect the viral replication by altering the expression of the host dependency factors that are essential for efficient HIV-1 gene expression. Both the host restriction and dependency factors determine the viral replication efficiency; however, the understanding of the IRepGs implicated in HIV-1 infection remains greatly limited at present. This review provides a comprehensive overview of the current understanding regarding the impact of the RNA-binding protein families, specifically the two families of splicing-associated proteins SRSF and hnRNP, on HIV-1 gene expression and viral replication. Since the recent findings show specifically that SRSF1 and hnRNP A0 are regulated by IFN-I in various cell lines and primary cells, including intestinal lamina propria mononuclear cells (LPMCs) and peripheral blood mononuclear cells (PBMCs), we particularly discuss their role in the context of the innate immunity affecting HIV-1 replication.
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Affiliation(s)
- Fabian Roesmann
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Lisa Müller
- Institute of Virology, Medical Faculty, University Hospital Düsseldorf, Heinrich-Heine-University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Katleen Klaassen
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Stefanie Heß
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
| | - Marek Widera
- Institute for Medical Virology, University Hospital Frankfurt, Goethe University Frankfurt, Paul-Ehrlich-Str. 40, 60596 Frankfurt am Main, Germany
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Brownmiller T, Caplen NJ. The HNRNPF/H RNA binding proteins and disease. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1788. [PMID: 37042074 PMCID: PMC10523889 DOI: 10.1002/wrna.1788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 04/13/2023]
Abstract
The members of the HNRNPF/H family of heterogeneous nuclear RNA proteins-HNRNPF, HNRNPH1, HNRNPH2, HNRNPH3, and GRSF1, are critical regulators of RNA maturation. Documented functions of these proteins include regulating splicing, particularly alternative splicing, 5' capping and 3' polyadenylation of RNAs, and RNA export. The assignment of these proteins to the HNRNPF/H protein family members relates to differences in the amino acid composition of their RNA recognition motifs, which differ from those of other RNA binding proteins (RBPs). HNRNPF/H proteins typically bind RNA sequences enriched with guanine (G) residues, including sequences that, in the presence of a cation, have the potential to form higher-order G-quadruplex structures. The need to further investigate members of the HNRNPF/H family of RBPs has intensified with the recent descriptions of their involvement in several disease states, including the pediatric tumor Ewing sarcoma and the hematological malignancy mantle cell lymphoma; newly described groups of developmental syndromes; and neuronal-related disorders, including addictive behavior. Here, to foster the study of the HNRNPF/H family of RBPs, we discuss features of the genes encoding these proteins, their structures and functions, and emerging contributions to disease. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Tayvia Brownmiller
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS, Bethesda, Maryland, USA
| | - Natasha J Caplen
- Functional Genetics Section, Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, DHHS, Bethesda, Maryland, USA
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Lim YH, Yoon G, Ryu Y, Jeong D, Song J, Kim YS, Ahn Y, Kook H, Kim YK. Human lncRNA SUGCT-AS1 Regulates the Proinflammatory Response of Macrophage. Int J Mol Sci 2023; 24:13315. [PMID: 37686120 PMCID: PMC10487982 DOI: 10.3390/ijms241713315] [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: 07/04/2023] [Revised: 08/20/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
Macrophages are the major primary immune cells that mediate the inflammatory response. In this process, long non-coding RNAs (lncRNAs) play an important, yet largely unknown role. Therefore, utilizing several publicly available RNA sequencing datasets, we predicted and selected lncRNAs that are differentially expressed in M1 or M2 macrophages and involved in the inflammatory response. We identified SUGCT-AS1, which is a human macrophage-specific lncRNA whose expression is increased upon M1 macrophage stimulation. Conditioned media of SUGCT-AS1-depleted M1 macrophages induced an inflammatory phenotype of vascular smooth muscle cells, which included increased expression of inflammatory genes (IL1B and IL6), decreased contractile marker proteins (ACTA2 and SM22α), and increased cell migration. Depletion of SUGCT-AS1 promoted the expression and secretion of proinflammatory cytokines, such as TNF, IL1B, and IL6, in M1 macrophages, and transcriptomic analysis showed that SUGCT-AS1 has functions related to inflammatory responses and cytokines. Furthermore, we found that SUGCT-AS1 directly binds to hnRNPU and regulates its nuclear-cytoplasmic translocation. This translocation of hnRNPU altered the proportion of the MALT1 isoforms by regulating the alternative splicing of MALT1, a mediator of NF-κB signaling. Overall, our findings suggest that lncRNAs can be used for future studies on macrophage regulation. Moreover, they establish the SUGCT-AS1/hnRNPU/MALT1 axis, which is a novel inflammatory regulatory mechanism in macrophages.
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Affiliation(s)
- Yeong-Hwan Lim
- Basic Research Laboratory for Vascular Remodeling, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
| | - Gwangho Yoon
- Division of Brain Disease Research, Department for Chronic Disease Convergence Research, Korea National Institute of Health, Cheongju 28159, Republic of Korea
| | - Yeongseo Ryu
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
| | - Dahee Jeong
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
| | - Juhyun Song
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
| | - Yong Sook Kim
- Basic Research Laboratory for Vascular Remodeling, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Cell Regeneration Research Center, Chonnam National University Hospital, Gwangju 61469, Republic of Korea
- Biomedical Research Institute, Chonnam National University Hospital, Gwangju 61469, Republic of Korea
| | - Youngkeun Ahn
- Basic Research Laboratory for Vascular Remodeling, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Cell Regeneration Research Center, Chonnam National University Hospital, Gwangju 61469, Republic of Korea
- Department of Cardiology, Chonnam National University Medical School, Gwangju 61469, Republic of Korea
| | - Hyun Kook
- Basic Research Laboratory for Vascular Remodeling, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
- Department of Pharmacology, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
| | - Young-Kook Kim
- Basic Research Laboratory for Vascular Remodeling, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Republic of Korea
- BioMedical Sciences Graduate Program (BMSGP), Chonnam National University, Hwasun 58128, Republic of Korea
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Korff A, Yang X, O’Donovan K, Gonzalez A, Teubner BJ, Nakamura H, Messing J, Yang F, Carisey AF, Wang YD, Patni T, Sheppard H, Zakharenko SS, Chook YM, Taylor JP, Kim HJ. A murine model of hnRNPH2-related neurodevelopmental disorder reveals a mechanism for genetic compensation by Hnrnph1. J Clin Invest 2023; 133:e160309. [PMID: 37463454 PMCID: PMC10348767 DOI: 10.1172/jci160309] [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: 03/23/2022] [Accepted: 05/24/2023] [Indexed: 07/20/2023] Open
Abstract
Mutations in HNRNPH2 cause an X-linked neurodevelopmental disorder with features that include developmental delay, motor function deficits, and seizures. More than 90% of patients with hnRNPH2 have a missense mutation within or adjacent to the nuclear localization signal (NLS) of hnRNPH2. Here, we report that hnRNPH2 NLS mutations caused reduced interaction with the nuclear transport receptor Kapβ2 and resulted in modest cytoplasmic accumulation of hnRNPH2. We generated 2 knockin mouse models with human-equivalent mutations in Hnrnph2 as well as Hnrnph2-KO mice. Knockin mice recapitulated clinical features of the human disorder, including reduced survival in male mice, impaired motor and cognitive functions, and increased susceptibility to audiogenic seizures. In contrast, 2 independent lines of Hnrnph2-KO mice showed no detectable phenotypes. Notably, KO mice had upregulated expression of Hnrnph1, a paralog of Hnrnph2, whereas knockin mice failed to upregulate Hnrnph1. Thus, genetic compensation by Hnrnph1 may counteract the loss of hnRNPH2. These findings suggest that HNRNPH2-related disorder may be driven by a toxic gain of function or a complex loss of HNRNPH2 function with impaired compensation by HNRNPH1. The knockin mice described here are an important resource for preclinical studies to assess the therapeutic benefit of gene replacement or knockdown of mutant hnRNPH2.
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Affiliation(s)
- Ane Korff
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Xiaojing Yang
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Kevin O’Donovan
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Abner Gonzalez
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | - Haruko Nakamura
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - James Messing
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Fen Yang
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Alexandre F. Carisey
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Yong-Dong Wang
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | | | - Heather Sheppard
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | | | - Yuh Min Chook
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - J. Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland, USA
| | - Hong Joo Kim
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
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6
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Seese SE, Muheisen S, Gath N, Gross JM, Semina EV. Identification of HSPA8 as an interacting partner of MAB21L2 and an important factor in eye development. Dev Dyn 2023; 252:510-526. [PMID: 36576422 PMCID: PMC10947772 DOI: 10.1002/dvdy.560] [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: 06/19/2022] [Revised: 11/04/2022] [Accepted: 11/18/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Pathogenic variants in human MAB21L2 result in microphthalmia, anophthalmia, and coloboma. The exact molecular function of MAB21L2 is currently unknown. We conducted a series of yeast two-hybrid (Y2H) experiments to determine protein interactomes of normal human and zebrafish MAB21L2/mab21l2 as well as human disease-associated variant MAB21L2-p.(Arg51Gly) using human adult retina and zebrafish embryo libraries. RESULTS These screens identified klhl31, tnpo1, TNPO2/tnpo2, KLC2/klc2, and SPTBN1/sptbn1 as co-factors of MAB21L2/mab21l2. Several factors, including hspa8 and hspa5, were found to interact with MAB21L2-p.Arg51Gly but not wild-type MAB21L2/mab21l2 in Y2H screens. Further analyses via 1-by-1 Y2H assays, co-immunoprecipitation, and mass spectrometry revealed that both normal and variant MAB21L2 interact with HSPA5 and HSPA8. In situ hybridization detected co-expression of hspa5 and hspa8 with mab21l2 during eye development in zebrafish. Examination of zebrafish mutant hspa8hi138Tg identified reduced hspa8 expression associated with severe ocular developmental defects, including small eye, coloboma, and anterior segment dysgenesis. To investigate the effects of hspa8 deficiency on the mab21l2Arg51_Phe52del allele, corresponding zebrafish double mutants were generated and found to be more severely affected than single mutant lines. CONCLUSION This study identifies heat shock proteins as interacting partners of MAB21L2/mab21l2 and suggests a role for this interaction in vertebrate eye development.
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Affiliation(s)
- Sarah E. Seese
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Sanaa Muheisen
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Natalie Gath
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jeffrey M. Gross
- University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Elena V. Semina
- Department of Pediatrics The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cell Biology, Neurobiology and Anatomy, The Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Ophthalmology and Visual Sciences, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
- Children’s Research Institute, Medical College of Wisconsin, Children’s of Wisconsin, Milwaukee, WI 53226, USA
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7
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Fare CM, Rhine K, Lam A, Myong S, Shorter J. A minimal construct of nuclear-import receptor Karyopherin-β2 defines the regions critical for chaperone and disaggregation activity. J Biol Chem 2023; 299:102806. [PMID: 36529289 PMCID: PMC9860449 DOI: 10.1016/j.jbc.2022.102806] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Karyopherin-β2 (Kapβ2) is a nuclear-import receptor that recognizes proline-tyrosine nuclear localization signals of diverse cytoplasmic cargo for transport to the nucleus. Kapβ2 cargo includes several disease-linked RNA-binding proteins with prion-like domains, such as FUS, TAF15, EWSR1, hnRNPA1, and hnRNPA2. These RNA-binding proteins with prion-like domains are linked via pathology and genetics to debilitating degenerative disorders, including amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy. Remarkably, Kapβ2 prevents and reverses aberrant phase transitions of these cargoes, which is cytoprotective. However, the molecular determinants of Kapβ2 that enable these activities remain poorly understood, particularly from the standpoint of nuclear-import receptor architecture. Kapβ2 is a super-helical protein comprised of 20 HEAT repeats. Here, we design truncated variants of Kapβ2 and assess their ability to antagonize FUS aggregation and toxicity in yeast and FUS condensation at the pure protein level and in human cells. We find that HEAT repeats 8 to 20 of Kapβ2 recapitulate all salient features of Kapβ2 activity. By contrast, Kapβ2 truncations lacking even a single cargo-binding HEAT repeat display reduced activity. Thus, we define a minimal Kapβ2 construct for delivery in adeno-associated viruses as a potential therapeutic for amyotrophic lateral sclerosis/frontotemporal dementia, multisystem proteinopathy, and related disorders.
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Affiliation(s)
- Charlotte M Fare
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kevin Rhine
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland, USA; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Andrew Lam
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sua Myong
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland, USA; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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8
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Trothen SM, Zang RX, Lurie A, Dikeakos JD. PACS-1 contains distinct motifs for nuclear-cytoplasmic transport and interacts with the RNA-binding protein PTBP1 in the nucleus and cytosol. FEBS Lett 2022; 596:232-248. [PMID: 34822171 DOI: 10.1002/1873-3468.14243] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 11/08/2021] [Accepted: 11/09/2021] [Indexed: 11/10/2022]
Abstract
Phosphofurin acidic cluster sorting protein 1 (PACS-1) is canonically a cytosolic trafficking protein, yet recent reports have described nuclear roles for PACS-1. Herein, we sought to define the nuclear transport mechanism of PACS-1. We demonstrate that PACS-1 nucleocytoplasmic trafficking is dependent on its interaction with the nuclear transport receptors importin alpha 5 and exportin 1. PACS-1 nuclear entry and exit are defined by a nuclear localization signal (NLS, residues 311-318) and nuclear export signal (NES3, residues 366-375). Mutation of the PACS-1 NLS and NES3 altered the localization of a complex formed between PACS-1 and an RNA-binding protein, polypyrimidine tract-binding protein 1. Overall, we identify the nuclear localization mechanism of PACS-1 and highlight a potential role for PACS-1 in RNA-binding protein trafficking.
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Affiliation(s)
- Steven M Trothen
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Rong Xuan Zang
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Antony Lurie
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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Thibault PA, Ganesan A, Kalyaanamoorthy S, Clarke JPWE, Salapa HE, Levin MC. hnRNP A/B Proteins: An Encyclopedic Assessment of Their Roles in Homeostasis and Disease. BIOLOGY 2021; 10:biology10080712. [PMID: 34439945 PMCID: PMC8389229 DOI: 10.3390/biology10080712] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/16/2021] [Accepted: 07/21/2021] [Indexed: 12/13/2022]
Abstract
The hnRNP A/B family of proteins is canonically central to cellular RNA metabolism, but due to their highly conserved nature, the functional differences between hnRNP A1, A2/B1, A0, and A3 are often overlooked. In this review, we explore and identify the shared and disparate homeostatic and disease-related functions of the hnRNP A/B family proteins, highlighting areas where the proteins have not been clearly differentiated. Herein, we provide a comprehensive assembly of the literature on these proteins. We find that there are critical gaps in our grasp of A/B proteins' alternative splice isoforms, structures, regulation, and tissue and cell-type-specific functions, and propose that future mechanistic research integrating multiple A/B proteins will significantly improve our understanding of how this essential protein family contributes to cell homeostasis and disease.
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Affiliation(s)
- Patricia A. Thibault
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
| | - Aravindhan Ganesan
- ArGan’s Lab, School of Pharmacy, Faculty of Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - Subha Kalyaanamoorthy
- Department of Chemistry, Faculty of Science, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - Joseph-Patrick W. E. Clarke
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
| | - Hannah E. Salapa
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
| | - Michael C. Levin
- Office of the Saskatchewan Multiple Sclerosis Clinical Research Chair, University of Saskatchewan, Saskatoon, SK S7K 0M7, Canada; (P.A.T.); (J.-P.W.E.C.); (H.E.S.)
- Department of Medicine, Neurology Division, University of Saskatchewan, Saskatoon, SK S7N 0X8, Canada
- Department of Health Sciences, College of Medicine, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK S7N 5E5, Canada
- Correspondence:
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10
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Shen Q, Wang YE, Palazzo AF. Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection. J Biol Chem 2021; 297:100856. [PMID: 34097873 PMCID: PMC8254040 DOI: 10.1016/j.jbc.2021.100856] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/24/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.
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Affiliation(s)
- Qingtang Shen
- School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China.
| | - Yifan E Wang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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11
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Kalita J, Kapinos LE, Lim RYH. On the asymmetric partitioning of nucleocytoplasmic transport - recent insights and open questions. J Cell Sci 2021; 134:239102. [PMID: 33912945 DOI: 10.1242/jcs.240382] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Macromolecular cargoes are asymmetrically partitioned in the nucleus or cytoplasm by nucleocytoplasmic transport (NCT). At the center of this activity lies the nuclear pore complex (NPC), through which soluble factors circulate to orchestrate NCT. These include cargo-carrying importin and exportin receptors from the β-karyopherin (Kapβ) family and the small GTPase Ran, which switches between guanosine triphosphate (GTP)- and guanosine diphosphate (GDP)-bound forms to regulate cargo delivery and compartmentalization. Ongoing efforts have shed considerable light on how these soluble factors traverse the NPC permeability barrier to sustain NCT. However, this does not explain how importins and exportins are partitioned in the cytoplasm and nucleus, respectively, nor how a steep RanGTP-RanGDP gradient is maintained across the nuclear envelope. In this Review, we peel away the multiple layers of control that regulate NCT and juxtapose unresolved features against known aspects of NPC function. Finally, we discuss how NPCs might function synergistically with Kapβs, cargoes and Ran to establish the asymmetry of NCT.
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Affiliation(s)
- Joanna Kalita
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel CH4056, Switzerland
| | - Larisa E Kapinos
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel CH4056, Switzerland
| | - Roderick Y H Lim
- Biozentrum and the Swiss Nanoscience Institute, University of Basel, Basel CH4056, Switzerland
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12
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Mboukou A, Rajendra V, Kleinova R, Tisné C, Jantsch MF, Barraud P. Transportin-1: A Nuclear Import Receptor with Moonlighting Functions. Front Mol Biosci 2021; 8:638149. [PMID: 33681296 PMCID: PMC7930572 DOI: 10.3389/fmolb.2021.638149] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 01/13/2021] [Indexed: 12/11/2022] Open
Abstract
Transportin-1 (Trn1), also known as karyopherin-β2 (Kapβ2), is probably the best-characterized nuclear import receptor of the karyopherin-β family after Importin-β, but certain aspects of its functions in cells are still puzzling or are just recently emerging. Since the initial identification of Trn1 as the nuclear import receptor of hnRNP A1 ∼25 years ago, several molecular and structural studies have unveiled and refined our understanding of Trn1-mediated nuclear import. In particular, the understanding at a molecular level of the NLS recognition by Trn1 made a decisive step forward with the identification of a new class of NLSs called PY-NLSs, which constitute the best-characterized substrates of Trn1. Besides PY-NLSs, many Trn1 cargoes harbour NLSs that do not resemble the archetypical PY-NLS, which complicates the global understanding of cargo recognition by Trn1. Although PY-NLS recognition is well established and supported by several structures, the recognition of non-PY-NLSs by Trn1 is far less understood, but recent reports have started to shed light on the recognition of this type of NLSs. Aside from its principal and long-established activity as a nuclear import receptor, Trn1 was shown more recently to moonlight outside nuclear import. Trn1 has for instance been caught in participating in virus uncoating, ciliary transport and in modulating the phase separation properties of aggregation-prone proteins. Here, we focus on the structural and functional aspects of Trn1-mediated nuclear import, as well as on the moonlighting activities of Trn1.
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Affiliation(s)
- Allegra Mboukou
- Expression Génétique Microbienne, Institut de Biologie Physico-Chimique (IBPC), UMR 8261, CNRS, Université de Paris, Paris, France
| | - Vinod Rajendra
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Renata Kleinova
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Carine Tisné
- Expression Génétique Microbienne, Institut de Biologie Physico-Chimique (IBPC), UMR 8261, CNRS, Université de Paris, Paris, France
| | - Michael F. Jantsch
- Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Pierre Barraud
- Expression Génétique Microbienne, Institut de Biologie Physico-Chimique (IBPC), UMR 8261, CNRS, Université de Paris, Paris, France
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13
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Mehmood R, Jibiki K, Shibazaki N, Yasuhara N. Molecular profiling of nucleocytoplasmic transport factor genes in breast cancer. Heliyon 2021; 7:e06039. [PMID: 33553736 PMCID: PMC7851789 DOI: 10.1016/j.heliyon.2021.e06039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 12/14/2020] [Accepted: 01/14/2021] [Indexed: 11/24/2022] Open
Abstract
Transport of functional molecules across the nuclear membrane of a eukaryotic cell is regulated by a dedicated set of transporter proteins that carry molecules into the nucleus or out of the nucleus to the cytoplasm for homeostasis of the cell. One of the categories of cargo molecules these transporters carry are the molecules for cell cycle regulation. Therefore, their role is critical in terms of cancer development. Any misregulation of the transport factors would means aberrant abundance of cell cycle regulators and might have consequences in cell cycle progression. While earlier studies have focussed on individual transport related molecules, a collective overview of how these molecules may be dysregulated in breast cancer is lacking. Using genomic and transcriptomic datasets from TCGA (The Cancer Genome Atlas) and microarray platforms, we carried out bioinformatic analysis and provide a genetic and molecular profile of all the molecules directly related to nucleocytoplasmic shuttling of proteins and RNAs. Interestingly, we identified that many of these molecules are either mutated or have dysregulated expression in breast cancer. Strikingly, some of the molecules, namely, KPNA2, KPNA3, KPNA5, IPO8, TNPO1, XPOT, XPO7 and CSE1L were correlated with poor patient survival. This study provides a comprehensive genetic and molecular landscape of nucleocytoplasmic factors in breast cancer and points to the important roles of various nucleocytoplasmic factors in cancer progression. This data might have implications in prognosis and therapeutic targeting in breast cancer.
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Affiliation(s)
- Rashid Mehmood
- Department of Life Sciences, College of Science and General Studies, Alfaisal University, Riyadh, Kingdom of Saudi Arabia
| | - Kazuya Jibiki
- Graduate School of Integrated Basic Sciences, Nihon University, Setagaya-ku, Tokyo, Japan
| | - Noriko Shibazaki
- Graduate School of Integrated Basic Sciences, Nihon University, Setagaya-ku, Tokyo, Japan
| | - Noriko Yasuhara
- Graduate School of Integrated Basic Sciences, Nihon University, Setagaya-ku, Tokyo, Japan
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14
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Abstract
Influenza A virus (IAV) is an enveloped virus of the Orthomyxoviridae with a negative-sense single-stranded RNA genome. During virus cell entry, viral and cellular cues are delivered in a stepwise manner within two distinct cellular compartments-the endosomes and the cytosol. Endosome maturation primes the viral core for uncoating by cytosolic host proteins and host-mediated virus disaggregation is essential for genome import and replication in the nucleus. Recent evidence shows that two well-known cellular proteins-histone deacetylase 6 (HDAC6) and karyopherin-β2 (kapβ2)-uncoat influenza virus. HDAC6 is 1 of 11 HDACs and an X-linked, cytosolic lysine deacetylase. Under normal cellular conditions HDAC6 is the tubulin deacetylase. Under proteasomal stress HDAC6 binds unanchored ubiquitin, dynein and myosin II to sequester misfolded protein aggregates for autophagy. Kapβ2 is a member of the importin β family that transports RNA-binding proteins into the nucleus by binding to disordered nuclear localization signals (NLSs) known as PY-NLS. Kapβ2 is emerging as a universal uncoating factor for IAV and human immunodeficiency virus type 1 (HIV-1). Kapβ2 can also reverse liquid-liquid phase separation (LLPS) of RNA-binding proteins by promoting their disaggregation. Thus, it is becoming evident that key players in the management of cellular condensates and membraneless organelles are potent virus uncoating factors. This emerging concept reveals implications in viral pathogenesis, as well as, the promise for cell-targeted therapeutic strategies to block universal virus uncoating pathways hijacked by enveloped RNA viruses.
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Affiliation(s)
- Yohei Yamauchi
- School of Cellular & Molecular Medicine, University of Bristol, Bristol, United Kingdom.
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15
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Gong L, Wen T, Li Z, Wang Y, Wang J, Che X, Liu Y, Qu X. TNPO2 operates downstream of DYNC1I1 and promotes gastric cancer cell proliferation and inhibits apoptosis. Cancer Med 2019; 8:7299-7312. [PMID: 31605449 PMCID: PMC6885870 DOI: 10.1002/cam4.2582] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 09/11/2019] [Accepted: 09/15/2019] [Indexed: 12/19/2022] Open
Abstract
The import of proteins into the nucleus plays an important role in tumor development. In addition to the classical nuclear import proteins importin-β and importin-α, there are many nonclassical nuclear import proteins that include TNPO2. The role of TNPO2 as a nonclassical nuclear import protein in tumors is limited. Our previous studies have shown that DYNC1I1 is a poor prognostic factor for gastric cancer and can promote the proliferation and metastasis of gastric cancer cells. An expression profile chip showed that TNPO2 was its potential downstream. DYNC1I1 upregulated TNPO2 expression by upregulating SP1, following which, SP1 recruited and bound to the P300-acetylated TNPO2 promoter region histones, and thus promoted TNPO2 expression. At the same time, TNPO2 promoted gastric cancer cell proliferation and inhibited apoptosis by a mechanism that might be depending on the functional expression of P21.
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Affiliation(s)
- Libao Gong
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Ti Wen
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Zhi Li
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Yizhe Wang
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Jin Wang
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Xiaofang Che
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Yunpeng Liu
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
| | - Xiujuan Qu
- Department of Medical OncologyThe First Hospital of China Medical UniversityShenyangChina
- Key Laboratory of Anticancer Drugs and Biotherapy of Liaoning ProvinceThe First Hospital of China Medical UniversityShenyangChina
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16
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Fung L, Guzman H, Sevrioukov E, Idica A, Park E, Bochnakian A, Daugaard I, Jury D, Mortazavi A, Zisoulis DG, Pedersen IM. miR-128 Restriction of LINE-1 (L1) Retrotransposition Is Dependent on Targeting hnRNPA1 mRNA. Int J Mol Sci 2019; 20:E1955. [PMID: 31010097 PMCID: PMC6515209 DOI: 10.3390/ijms20081955] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/15/2019] [Accepted: 04/19/2019] [Indexed: 12/25/2022] Open
Abstract
The majority of the human genome is made of transposable elements, giving rise to interspaced repeats, including Long INterspersed Element-1s (LINE-1s or L1s). L1s are active human transposable elements involved in genomic diversity and evolution; however, they can also contribute to genomic instability and diseases. L1s require host factors to complete their life cycles, whereas the host has evolved numerous mechanisms to restrict L1-induced mutagenesis. Restriction mechanisms in somatic cells include methylation of the L1 promoter, anti-viral factors and RNA-mediated processes such as small RNAs. microRNAs (miRNAs or miRs) are small non-coding RNAs that post-transcriptionally repress multiple target genes often found in the same cellular pathways. We have recently established that miR-128 functions as a novel restriction factor inhibiting L1 mobilization in somatic cells. We have further demonstrated that miR-128 functions through a dual mechanism; by directly targeting L1 RNA for degradation and indirectly by inhibiting a cellular co-factor which L1 is dependent on to transpose to new genomic locations (TNPO1). Here, we add another piece to the puzzle of the enigmatic L1 lifecycle. We show that miR-128 also inhibits another key cellular factor, hnRNPA1 (heterogeneous nuclear ribonucleoprotein A1), by significantly reducing mRNA and protein levels through direct interaction with the coding sequence (CDS) of hnRNPA1 mRNA. In addition, we demonstrate that repression of hnRNPA1 using hnRNPA1-shRNA significantly decreases de novo L1 retro-transposition and that induced hnRNPA1 expression enhances L1 mobilization. Furthermore, we establish that hnRNPA1 is a functional target of miR-128. Finally, we determine that induced hnRNPA1 expression in miR-128-overexpressing cells can partly rescue the miR-128-induced repression of L1's ability to transpose to different genomic locations. Thus, we have identified an additional mechanism by which miR-128 represses L1 retro-transposition and mediates genomic stability.
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Affiliation(s)
- Lianna Fung
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Herlinda Guzman
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Evgueni Sevrioukov
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Adam Idica
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Eddie Park
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA.
| | - Aurore Bochnakian
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Iben Daugaard
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Douglas Jury
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Ali Mortazavi
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA.
| | - Dimitrios G Zisoulis
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
| | - Irene M Pedersen
- Department of Molecular Biology and Biochemistry, Francisco J. AyalaSchool of Biological Sciences, University of California, Irvine, CA 92697, USA.
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17
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A phylogenetically conserved hnRNP type A/B protein from squid brain. Neurosci Lett 2019; 696:219-224. [PMID: 30610890 DOI: 10.1016/j.neulet.2019.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/13/2018] [Accepted: 01/02/2019] [Indexed: 11/23/2022]
Abstract
Eukaryotic mRNA precursors are co-transcriptionally assembled into ribonucleoprotein complexes. Heterogeneous nuclear ribonucleoprotein (hnRNP) complexes are involved in mRNA translocation, stability, subcellular localization and regulation of mRNA translation. About 20 major classes of hnRNPs have been identified in mammals. In a previous work, we characterized a novel, strongly-basic, RNA-binding protein (p65) in presynaptic terminals of squid neurons presenting homology with human hnRNPA/B type proteins, likely involved in local mRNA processing. We have identified and sequenced two hnRNPA/B-like proteins associated with tissue purified squid p65: Protein 1 (36.3 kDa, IP 7.1) and Protein 2 (37.6 kDa, IP 8.9). In the present work we generated an in silico, tridimensional, structural model of squid hnRNPA/B-like Protein 2, which showed highly conserved secondary and tertiary structure of RNA recognition motifs with human hnRNPA1 protein, as well as illustrated the potential for squid Protein 2 stable homodimerization. This was supported by biophysical measurements of bacterially expressed, recombinant protein. In addition, we induced expression of squid hnRNPA/B-like Protein 2 in human neuroblastoma cells (SH-SY5Y) and observed an exclusively nuclear localization, which depended on an intact C-terminal amino acid sequence and which relocated to cytoplasm particles containing PABP when the cells were challenged with sorbitol, suggesting an involvement with stress granule function.
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18
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Larrieu D, Viré E, Robson S, Breusegem SY, Kouzarides T, Jackson SP. Inhibition of the acetyltransferase NAT10 normalizes progeric and aging cells by rebalancing the Transportin-1 nuclear import pathway. Sci Signal 2018; 11:eaar5401. [PMID: 29970603 PMCID: PMC6331045 DOI: 10.1126/scisignal.aar5401] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is an incurable premature aging disease. Identifying deregulated biological processes in HGPS might thus help define novel therapeutic strategies. Fibroblasts from HGPS patients display defects in nucleocytoplasmic shuttling of the GTP-bound form of the small GTPase Ran (RanGTP), which leads to abnormal transport of proteins into the nucleus. We report that microtubule stabilization in HGPS cells sequestered the nonclassical nuclear import protein Transportin-1 (TNPO1) in the cytoplasm, thus affecting the nuclear localization of its cargo, including the nuclear pore protein NUP153. Consequently, nuclear Ran, nuclear anchorage of the nucleoporin TPR, and chromatin organization were disrupted, deregulating gene expression and inducing senescence. Inhibiting N-acetyltransferase 10 (NAT10) ameliorated HGPS phenotypes by rebalancing the nuclear to cytoplasmic ratio of TNPO1. This restored nuclear pore complex integrity and nuclear Ran localization, thereby correcting HGPS cellular phenotypes. We observed a similar mechanism in cells from healthy aged individuals. This study identifies a nuclear import pathway affected in aging and underscores the potential for NAT10 inhibition as a possible therapeutic strategy for HGPS and perhaps also for pathologies associated with normal aging.
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Affiliation(s)
- Delphine Larrieu
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK.
| | - Emmanuelle Viré
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK
| | - Samuel Robson
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK
| | - Sophia Y Breusegem
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK
| | - Tony Kouzarides
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK
| | - Stephen P Jackson
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Biochemistry, University of Cambridge, CB2 1QN, UK.
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19
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Abstract
Chikungunya virus (CHIKV) was discovered more than six decades ago, but has remained poorly investigated. However, after a recent outbreak of CHIK fever in both hemispheres and viral adaptation to new species of mosquitoes, it has attracted a lot of attention. The currently available experimental data suggest that molecular mechanisms of CHIKV replication in vertebrate and mosquito cells are similar to those of other New and Old World alphaviruses. However, this virus exhibits a number of unique characteristics that distinguish it from the other, better studied members of the alphavirus genus. This review is an attempt to summarize the data accumulated thus far regarding the molecular mechanisms of alphavirus RNA replication and interaction with host cells. Emphasis was placed on demonstrating the distinct features of CHIKV in utilizing host factors to build replication complexes and modify the intracellular environment for efficient viral replication and inhibition of the innate immune response. The available data suggest that our knowledge about alphavirus replication contains numerous gaps that potentially hamper the development of new therapeutic means against CHIKV and other pathogenic alphaviruses.
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Affiliation(s)
- I Frolov
- Department of Microbiology, University of Alabama at Birmingham, 1720 2nd Ave South, BBRB373/Box 3, 35294-2170, Birmingham, AL, USA.
| | - E I Frolova
- Department of Microbiology, University of Alabama at Birmingham, 1720 2nd Ave South, BBRB373/Box 3, 35294-2170, Birmingham, AL, USA
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20
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Idica A, Sevrioukov EA, Zisoulis DG, Hamdorf M, Daugaard I, Kadandale P, Pedersen IM. MicroRNA miR-128 represses LINE-1 (L1) retrotransposition by down-regulating the nuclear import factor TNPO1. J Biol Chem 2017; 292:20494-20508. [PMID: 28974576 DOI: 10.1074/jbc.m117.807677] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 09/20/2017] [Indexed: 01/04/2023] Open
Abstract
Repetitive elements, including LINE-1 (L1), comprise approximately half of the human genome. These elements can potentially destabilize the genome by initiating their own replication and reintegration into new sites (retrotransposition). In somatic cells, transcription of L1 elements is repressed by distinct molecular mechanisms, including DNA methylation and histone modifications, to repress transcription. Under conditions of hypomethylation (e.g. in tumor cells), a window of opportunity for L1 derepression arises, and additional restriction mechanisms become crucial. We recently demonstrated that the microRNA miR-128 represses L1 activity by directly binding to L1 ORF2 RNA. In this study, we tested whether miR-128 can also control L1 activity by repressing cellular proteins important for L1 retrotransposition. We found that miR-128 targets the 3' UTR of nuclear import factor transportin 1 (TNPO1) mRNA. Manipulation of miR-128 and TNPO1 levels demonstrated that induction or depletion of TNPO1 affects L1 retrotransposition and nuclear import of an L1-ribonucleoprotein complex (using L1-encoded ORF1p as a proxy for L1-ribonucleoprotein complexes). Moreover, TNPO1 overexpression partially reversed the repressive effect of miR-128 on L1 retrotransposition. Our study represents the first description of a protein factor involved in nuclear import of the L1 element and demonstrates that miR-128 controls L1 activity in somatic cells through two independent mechanisms: direct binding to L1 RNA and regulation of a cellular factor necessary for L1 nuclear import and retrotransposition.
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Affiliation(s)
- Adam Idica
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Evgueni A Sevrioukov
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Dimitrios G Zisoulis
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Matthias Hamdorf
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Iben Daugaard
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Pavan Kadandale
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
| | - Irene M Pedersen
- From the Department of Molecular Biology and Biochemistry, Francisco J. Ayala School of Biological Sciences, University of California, Irvine, California 92697
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21
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Fu G, Tu LC, Zilman A, Musser SM. Investigating molecular crowding within nuclear pores using polarization-PALM. eLife 2017; 6:e28716. [PMID: 28949296 PMCID: PMC5693140 DOI: 10.7554/elife.28716] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/25/2017] [Indexed: 12/25/2022] Open
Abstract
The key component of the nuclear pore complex (NPC) controlling permeability, selectivity, and the speed of nucleocytoplasmic transport is an assembly of natively unfolded polypeptides, which contain phenylalanine-glycine (FG) binding sites for nuclear transport receptors. The architecture and dynamics of the FG-network have been refractory to characterization due to the paucity of experimental methods able to probe the mobility and density of the FG-polypeptides and embedded macromolecules within intact NPCs. Combining fluorescence polarization, super-resolution microscopy, and mathematical analyses, we examined the rotational mobility of fluorescent probes at various locations within the FG-network under different conditions. We demonstrate that polarization PALM (p-PALM) provides a rich source of information about low rotational mobilities that are inaccessible with bulk fluorescence anisotropy approaches, and anticipate that p-PALM is well-suited to explore numerous crowded cellular environments. In total, our findings indicate that the NPC's internal organization consists of multiple dynamic environments with different local properties.
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Affiliation(s)
- Guo Fu
- Department of Molecular and Cellular Medicine, College of MedicineThe Texas A&M University Health Science CenterCollege StationUnited States
| | - Li-Chun Tu
- Department of Molecular and Cellular Medicine, College of MedicineThe Texas A&M University Health Science CenterCollege StationUnited States
| | - Anton Zilman
- Department of PhysicsUniversity of TorontoTorontoCanada
- Institute for Biomaterials and Biomedical EngineeringUniversity of TorontoTorontoCanada
| | - Siegfried M Musser
- Department of Molecular and Cellular Medicine, College of MedicineThe Texas A&M University Health Science CenterCollege StationUnited States
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22
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Kapeli K, Martinez FJ, Yeo GW. Genetic mutations in RNA-binding proteins and their roles in ALS. Hum Genet 2017; 136:1193-1214. [PMID: 28762175 PMCID: PMC5602095 DOI: 10.1007/s00439-017-1830-7] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 07/17/2017] [Indexed: 12/11/2022]
Abstract
Mutations in genes that encode RNA-binding proteins (RBPs) have emerged as critical determinants of neurological diseases, especially motor neuron disorders such as amyotrophic lateral sclerosis (ALS). RBPs are involved in all aspects of RNA processing, controlling the life cycle of RNAs from synthesis to degradation. Hallmark features of RBPs in neuron dysfunction include misregulation of RNA processing, mislocalization of RBPs to the cytoplasm, and abnormal aggregation of RBPs. Much progress has been made in understanding how ALS-associated mutations in RBPs drive pathogenesis. Here, we focus on several key RBPs involved in ALS—TDP-43, HNRNP A2/B1, HNRNP A1, FUS, EWSR1, and TAF15—and review our current understanding of how mutations in these proteins cause disease.
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Affiliation(s)
- Katannya Kapeli
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore
| | - Fernando J Martinez
- Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Gene W Yeo
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117593, Singapore.
- Department of Cellular and Molecular Medicine, Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, 92093, USA.
- Molecular Engineering Laboratory, A*STAR, Singapore, 138673, Singapore.
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23
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Roth S, Khalaila I. The effect of O -GlcNAcylation on hnRNP A1 translocation and interaction with transportin1. Exp Cell Res 2017; 350:210-217. [DOI: 10.1016/j.yexcr.2016.11.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 11/16/2016] [Accepted: 11/28/2016] [Indexed: 01/03/2023]
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24
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Wall ML, Lewis SM. Methylarginines within the RGG-Motif Region of hnRNP A1 Affect Its IRES Trans-Acting Factor Activity and Are Required for hnRNP A1 Stress Granule Localization and Formation. J Mol Biol 2016; 429:295-307. [PMID: 27979648 DOI: 10.1016/j.jmb.2016.12.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/22/2016] [Accepted: 12/08/2016] [Indexed: 12/30/2022]
Abstract
Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a stress granule-associated RNA-binding protein that plays a role in apoptosis and cellular stress recovery. HnRNP A1 is a major non-histone target of protein arginine methyltransferase 1, which asymmetrically dimethylates hnRNP A1 at several key arginine residues within its arginine-glycine-glycine (RGG)-motif region. Although arginine methylation is known to regulate general RNA binding of hnRNP A1 in vitro, the functional role of arginine methylation in hnRNP A1 cytoplasmic activity is unknown. To test the impact of key methylarginine residues on hnRNP A1 cytoplasmic activity and stress granule association, cytoplasmically restricted Flag-tagged mutants of hnRNP A1 were generated in which key methylarginine residues within the RGG-motif region were changed to either lysine or alanine. Lysine substitution, which mimics unmethylated arginine, resulted in a 40% increase in internal ribosome entry site trans-acting factor (ITAF) activity and the protein readily associates with stress granules. Alanine substitution resulted in a loss of ITAF activity and reduced mRNA binding. The alanine mutant also displays reduced stress granule association and suppresses stress granule formation. Our data suggest that arginine residues within the RGG-motif region are critical for hnRNP A1 cytoplasmic activities and that endogenous asymmetric dimethylation of the RGG-motif region suppresses hnRNP A1 ITAF activity in cells. Our findings indicate that methylarginine residues within the RGG-motif region of hnRNP A1 are important for its cytoplasmic activities and that hypomethylation and/or mutation of the RGG-motif region may contribute to the role of hnRNP A1 in diseases such as cancer.
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Affiliation(s)
- Michael L Wall
- Atlantic Cancer Research Institute, Moncton, New Brunswick, Canada
| | - Stephen M Lewis
- Atlantic Cancer Research Institute, Moncton, New Brunswick, Canada; Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Biology, University of New Brunswick, Saint John, New Brunswick, Canada; Department of Chemistry & Biochemistry, Université de Moncton, Moncton, New Brunswick, Canada.
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25
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Martinez FJ, Pratt GA, Van Nostrand EL, Batra R, Huelga SC, Kapeli K, Freese P, Chun SJ, Ling K, Gelboin-Burkhart C, Fijany L, Wang HC, Nussbacher JK, Broski SM, Kim HJ, Lardelli R, Sundararaman B, Donohue JP, Javaherian A, Lykke-Andersen J, Finkbeiner S, Bennett CF, Ares M, Burge CB, Taylor JP, Rigo F, Yeo GW. Protein-RNA Networks Regulated by Normal and ALS-Associated Mutant HNRNPA2B1 in the Nervous System. Neuron 2016; 92:780-795. [PMID: 27773581 DOI: 10.1016/j.neuron.2016.09.050] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/25/2016] [Accepted: 09/20/2016] [Indexed: 12/11/2022]
Abstract
HnRNPA2B1 encodes an RNA binding protein associated with neurodegeneration. However, its function in the nervous system is unclear. Transcriptome-wide crosslinking and immunoprecipitation in mouse spinal cord discover UAGG motifs enriched within ∼2,500 hnRNP A2/B1 binding sites and an unexpected role for hnRNP A2/B1 in alternative polyadenylation. HnRNP A2/B1 loss results in alternative splicing (AS), including skipping of an exon in amyotrophic lateral sclerosis (ALS)-associated D-amino acid oxidase (DAO) that reduces D-serine metabolism. ALS-associated hnRNP A2/B1 D290V mutant patient fibroblasts and motor neurons differentiated from induced pluripotent stem cells (iPSC-MNs) demonstrate abnormal splicing changes, likely due to increased nuclear-insoluble hnRNP A2/B1. Mutant iPSC-MNs display decreased survival in long-term culture and exhibit hnRNP A2/B1 localization to cytoplasmic granules as well as exacerbated changes in gene expression and splicing upon cellular stress. Our findings provide a cellular resource and reveal RNA networks relevant to neurodegeneration, regulated by normal and mutant hnRNP A2/B1. VIDEO ABSTRACT.
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Affiliation(s)
- Fernando J Martinez
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Gabriel A Pratt
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioinformatics and Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eric L Van Nostrand
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ranjan Batra
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Stephanie C Huelga
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Katannya Kapeli
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Peter Freese
- Department of Biology, MIT, Cambridge, MA 02139, USA
| | | | - Karen Ling
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - Chelsea Gelboin-Burkhart
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Layla Fijany
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Harrison C Wang
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Julia K Nussbacher
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sara M Broski
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Hong Joo Kim
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Rea Lardelli
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Balaji Sundararaman
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA
| | - John P Donohue
- Department of Molecular, Cell, and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Ashkan Javaherian
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Jens Lykke-Andersen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Steven Finkbeiner
- Taube/Koret Center for Neurodegenerative Disease Research, Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Departments of Neurology and Physiology, University of California, San Francisco, San Francisco, CA 94107, USA
| | | | - Manuel Ares
- Department of Molecular, Cell, and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | | | - J Paul Taylor
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - Gene W Yeo
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Stem Cell Program and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioinformatics and Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore; Molecular Engineering Laboratory, A(∗)STAR, Singapore 138673, Singapore.
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26
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Madugula V, Lu L. A ternary complex comprising transportin1, Rab8 and the ciliary targeting signal directs proteins to ciliary membranes. J Cell Sci 2016; 129:3922-3934. [PMID: 27633000 PMCID: PMC5087665 DOI: 10.1242/jcs.194019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/31/2016] [Indexed: 12/13/2022] Open
Abstract
The sensory functions of cilia are dependent on the enrichment of cilium-resident proteins. Although it is known that ciliary targeting signals (CTSs) specifically target ciliary proteins to cilia, it is still unclear how CTSs facilitate the entry and retention of cilium-resident proteins at the molecular level. We found that non-ciliary membrane reporters can passively diffuse into cilia through the lateral transport pathway, and the translocation of membrane reporters through the ciliary diffusion barrier is facilitated by importin binding motifs and domains. Screening known CTSs of ciliary membrane residents uncovered that fibrocystin, photoreceptor retinol dehydrogenase, rhodopsin and retinitis pigmentosa 2 interact with transportin1 (TNPO1) through previously identified CTSs. We further discovered that a new ternary complex, comprising TNPO1, Rab8 and a CTS, can assemble or disassemble under the guanine nucleotide exchange activity of Rab8. Our study suggests a new mechanism in which the TNPO1-Rab8-CTS complex mediates selective entry into and retention of cargos within cilia.
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Affiliation(s)
- Viswanadh Madugula
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
| | - Lei Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore
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27
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Lewinski M, Hallmann A, Staiger D. Genome-wide identification and phylogenetic analysis of plant RNA binding proteins comprising both RNA recognition motifs and contiguous glycine residues. Mol Genet Genomics 2015; 291:763-73. [DOI: 10.1007/s00438-015-1144-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 11/06/2015] [Indexed: 11/28/2022]
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28
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Yang Y, Jia D, Kim H, Abd Elmageed ZY, Datta A, Davis R, Srivastav S, Moroz K, Crawford BE, Moparty K, Thomas R, Hudson RS, Ambs S, Abdel-Mageed AB. Dysregulation of miR-212 Promotes Castration Resistance through hnRNPH1-Mediated Regulation of AR and AR-V7: Implications for Racial Disparity of Prostate Cancer. Clin Cancer Res 2015; 22:1744-56. [PMID: 26553749 DOI: 10.1158/1078-0432.ccr-15-1606] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/11/2015] [Indexed: 12/31/2022]
Abstract
PURPOSE The causes of disproportionate incidence and mortality of prostate cancer among African Americans (AA) remain elusive. The purpose of this study was to investigate the mechanistic role and assess clinical utility of the splicing factor heterogeneous nuclear ribonucleoprotein H1 (hnRNP H1) in prostate cancer progression among AA men. EXPERIMENTAL DESIGN We employed an unbiased functional genomics approach coupled with suppressive subtractive hybridization (SSH) and custom cDNA microarrays to identify differentially expressed genes in microdissected tumors procured from age- and tumor grade-matched AA and Caucasian American (CA) men. Validation analysis was performed in independent cohorts and tissue microarrays. The underlying mechanisms of hnRNPH1 regulation and its impact on androgen receptor (AR) expression and tumor progression were explored. RESULTS Aberrant coexpression of AR and hnRNPH1 and downregulation of miR-212 were detected in prostate tumors and correlate with disease progression in AA men compared with CA men. Ectopic expression of miR-212 mimics downregulated hnRNPH1 transcripts, which in turn reduced expression of AR and its splice variant AR-V7 (or AR3) in prostate cancer cells. hnRNPH1 physically interacts with AR and steroid receptor coactivator-3 (SRC-3) and primes activation of androgen-regulated genes in a ligand-dependent and independent manner. siRNA silencing of hnRNPH1 sensitized prostate cancer cells to bicalutamide and inhibited prostate tumorigenesis in vivo CONCLUSIONS Our findings define novel roles for hnRNPH1 as a putative oncogene, splicing factor, and an auxiliary AR coregulator. Targeted disruption of the hnRNPH1-AR axis may have therapeutic implications to improve clinical outcomes in patients with advanced prostate cancer, especially among AA men.
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Affiliation(s)
- Yijun Yang
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Dingwu Jia
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Hogyoung Kim
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana
| | | | - Amrita Datta
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Rodney Davis
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Sudesh Srivastav
- Department of Biostatistics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana
| | - Krzysztof Moroz
- Department of Pathology, Tulane University School of Medicine, New Orleans, Louisiana. Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Byron E Crawford
- Department of Pathology, Tulane University School of Medicine, New Orleans, Louisiana
| | - Krishnarao Moparty
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana. Division of Urology, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana
| | - Raju Thomas
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana. Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana
| | - Robert S Hudson
- Laboratory of Human Carcinogenesis, National Cancer Institute, NIH, Bethesda, Maryland
| | - Stefan Ambs
- Laboratory of Human Carcinogenesis, National Cancer Institute, NIH, Bethesda, Maryland
| | - Asim B Abdel-Mageed
- Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana. Tulane Cancer Center, Tulane University School of Medicine, New Orleans, Louisiana. Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana.
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29
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Hwang B, McCool K, Wan J, Wuerzberger-Davis SM, Young EWK, Choi EY, Cingolani G, Weaver BA, Miyamoto S. IPO3-mediated Nonclassical Nuclear Import of NF-κB Essential Modulator (NEMO) Drives DNA Damage-dependent NF-κB Activation. J Biol Chem 2015; 290:17967-17984. [PMID: 26060253 DOI: 10.1074/jbc.m115.645960] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Indexed: 11/06/2022] Open
Abstract
Activation of IκB kinase (IKK) and NF-κB by genotoxic stresses modulates apoptotic responses and production of inflammatory mediators, thereby contributing to therapy resistance and premature aging. We previously reported that genotoxic agents induce nuclear localization of NF-κB essential modulator (NEMO) via an undefined mechanism to arbitrate subsequent DNA damage-dependent IKK/NF-κB signaling. Here we show that a nonclassical nuclear import pathway via IPO3 (importin 3, transportin 2) mediates stress-induced NEMO nuclear translocation. We found putative nuclear localization signals in NEMO whose mutations disrupted stress-inducible nuclear translocation of NEMO and IKK/NF-κB activation in stably reconstituted NEMO-deficient cells. RNAi screening of both importin α and β family members, as well as co-immunoprecipitation analyses, revealed that a nonclassical importin β family member, IPO3, was the only importin that was able to associate with NEMO and whose reduced expression prevented genotoxic stress-induced NEMO nuclear translocation, IKK/NF-κB activation, and inflammatory cytokine transcription. Recombinant IPO3 interacted with recombinant NEMO but not the nuclear localization signal mutant version and induced nuclear import of NEMO in digitonin-permeabilized cells. We also provide evidence that NEMO is disengaged from IKK complex following genotoxic stress induction. Thus, the IPO3 nuclear import pathway is an early and crucial determinant of the IKK/NF-κB signaling arm of the mammalian DNA damage response.
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Affiliation(s)
- Byounghoon Hwang
- Department of Oncology, University of Wisconsin, Madison, Wisconsin
| | - Kevin McCool
- Department of Oncology, University of Wisconsin, Madison, Wisconsin; Molecular and Cellular Pharmacology Program, University of Wisconsin, Madison, Wisconsin
| | - Jun Wan
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, Wisconsin
| | - Shelly M Wuerzberger-Davis
- Department of Oncology, University of Wisconsin, Madison, Wisconsin; University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Wisconsin
| | - Edmond W K Young
- Department of Mechanical and Industrial Engineering and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada
| | - Eun Young Choi
- Department of Oncology, University of Wisconsin, Madison, Wisconsin
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Beth A Weaver
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, Wisconsin; University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Wisconsin
| | - Shigeki Miyamoto
- Department of Oncology, University of Wisconsin, Madison, Wisconsin; University of Wisconsin Carbone Cancer Center, University of Wisconsin, Madison, Wisconsin.
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30
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Renusch SR, Harshman S, Pi H, Workman E, Wehr A, Li X, Prior TW, Elsheikh BH, Swoboda KJ, Simard LR, Kissel JT, Battle D, Parthun MR, Freitas MA, Kolb SJ. Spinal Muscular Atrophy Biomarker Measurements from Blood Samples in a Clinical Trial of Valproic Acid in Ambulatory Adults. J Neuromuscul Dis 2015; 2:119-130. [PMID: 27858735 PMCID: PMC5271431 DOI: 10.3233/jnd-150081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background: Clinical trials of therapies for spinal muscular atrophy (SMA) that are designed to increase the expression the SMN protein ideally include careful assessment of relevant SMN biomarkers. Objective: In the SMA VALIANT trial, a recent double-blind placebo-controlled crossover study of valproic acid (VPA) in ambulatory adult subjects with SMA, we investigated relevant pharmacodynamic biomarkers in blood samples from SMA subjects by direct longitudinal measurement of histone acetylation and SMN mRNA and protein levels in the presence and absence of VPA treatment. Methods: Thirty-three subjects were randomized to either VPA or placebo for the first 6 months followed by crossover to the opposite arm for an additional 6 months. Outcome measures were compared between the two treatments (VPA and placebo) using a standard crossover analysis. Results: A significant increase in histone H4 acetylation was observed with VPA treatment (p = 0.005). There was insufficient evidence to suggest a treatment effect with either full length or truncated SMN mRNA transcript levels or SMN protein levels. Conclusions: These measures were consistent with the observed lack of change in the primary clinical outcome measure in the VALIANT trial. These results also highlight the added benefit of molecular and pharmacodynamic biomarker measurements in the interpretation of clinical trial outcomes.
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Affiliation(s)
- Samantha R Renusch
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sean Harshman
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Hongyang Pi
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Eileen Workman
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Allison Wehr
- Center for Biostatistics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Xiaobai Li
- Center for Biostatistics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Thomas W Prior
- Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Bakri H Elsheikh
- Department of Neurology, Dhahran Medical Center, Dhahran, Saudi Arabia
| | - Kathryn J Swoboda
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Louise R Simard
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - John T Kissel
- Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Daniel Battle
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Mark R Parthun
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Michael A Freitas
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Stephen J Kolb
- Department of Molecular & Cellular Biochemistry, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Neurology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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31
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Masaki S, Yoshimoto R, Kaida D, Hata A, Satoh T, Ohno M, Kataoka N. Identification of the specific interactors of the human lariat RNA debranching enzyme 1 protein. Int J Mol Sci 2015; 16:3705-21. [PMID: 25671812 PMCID: PMC4346921 DOI: 10.3390/ijms16023705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/04/2015] [Indexed: 01/30/2023] Open
Abstract
In eukaryotes, pre-mRNA splicing is an essential step for gene expression. We have been analyzing post-splicing intron turnover steps in higher eukaryotes. Here, we report protein interaction between human Debranching enzyme 1 (hDbr1) and several factors found in the Intron Large (IL) complex, which is an intermediate complex of the intron degradation pathway. The hDbr1 protein specifically interacts with xeroderma pigmentosum, complementeation group A (XPA)-binding protein 2 (Xab2). We also attempted to identify specific interactors of hDbr1. Co-immunoprecipitation experiments followed by mass spectrometry analysis identified a novel protein as one of the specific interactors of hDbr1. This protein is well conserved among many species and shows the highest similarity to yeast Drn1, so it is designated as human Dbr1 associated ribonuclease 1 (hDrn1). hDrn1 directly interacts with hDbr1 through protein–protein interaction. Furthermore, hDrn1 shuttles between the nucleus and the cytoplasm, as hDbr1 protein does. These findings suggest that hDrn1 has roles in both the nucleus and the cytoplasm, which are highly likely to involve hDbr1.
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Affiliation(s)
- So Masaki
- Medical Innovation Center, Laboratory for Malignancy Control Research, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Rei Yoshimoto
- Chemical Genetics Laboratory, RIKEN Advanced Science Institute, Wako, Saitama 351-0198, Japan.
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
- Division of Gene Expression Mechanism, Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
| | - Daisuke Kaida
- Frontier Research Core for Life Sciences, University of Toyama, 2630 Sugitani, Toyama-shi, Toyama 930-0194, Japan.
| | - Asuka Hata
- Medical Innovation Center, Laboratory for Malignancy Control Research, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Takayuki Satoh
- Frontier Research Core for Life Sciences, University of Toyama, 2630 Sugitani, Toyama-shi, Toyama 930-0194, Japan.
| | - Mutsuhito Ohno
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Naoyuki Kataoka
- Medical Innovation Center, Laboratory for Malignancy Control Research, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan.
- Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto 606-8507, Japan.
- Medical Top Track Program, Medical Research Institute, Tokyo Dental and Medical University, Tokyo 113-8510, Japan.
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32
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Bao W, Florea L, Wu N, Wang Z, Banaudha K, Qian J, Houzet L, Kumar R, Kumar A. Loss of nuclear PTEN in HCV-infected human hepatocytes. Infect Agent Cancer 2014; 9:23. [PMID: 25075209 PMCID: PMC4114100 DOI: 10.1186/1750-9378-9-23] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 06/26/2014] [Indexed: 02/04/2023] Open
Abstract
Background Hepatitis C virus (HCV) infection is a major risk factor for chronic hepatitis and hepatocellular carcinoma (HCC); however, the mechanism of HCV-mediated hepatocarcinogenesis is not well understood. Insufficiency of PTEN tumor suppressor is associated with more aggressive cancers, including HCC. We asked whether viral non-coding RNA could initiate oncogenesis in HCV infected human hepatocytes. The results presented herein suggest that loss of nuclear PTEN in HCV-infected human hepatocytes results from depletion of Transportin-2, which is a direct target of viral non-coding RNA, vmr11. Methods The intracellular distribution of PTEN in HCV-infected cells was monitored by immunostaining and Western blots of nuclear and cytoplasmic proteins. Effects of PTEN depletion were examined by comparing expression arrays of uninfected cells with either HCV-infected or vmr11-transfected cells. Target genes suggested by array analyses were validated by Western blot. The influence of nuclear PTEN deficiency on virus production was determined by quantitative analysis of HCV genomic RNA in culture media of infected hepatocytes. Results Import of PTEN to the nucleus relies on the interaction of Transportin-2 and PTEN proteins; we show that depletion of Transportin-2 by HCV infection or by the introduction of vmr11 in uninfected cells results in reduced nuclear PTEN. In turn, nuclear PTEN insufficiency correlates with increased virus production and the induction of γ-H2AX, a marker of DNA double-strand breaks and genomic instability. Conclusion An HCV-derived small non-coding RNA inhibits Transportin-2 and PTEN translocation to the nucleus, suggesting a direct viral role in hepatic oncogenesis.
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Affiliation(s)
- Wenjie Bao
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
| | - Liliana Florea
- McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University, Baltimore, MD, USA
| | - Ningbin Wu
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
| | - Zhao Wang
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
| | - Krishna Banaudha
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
| | - Jason Qian
- Current address: Metabolism Branch, NIH, Bethesda, MD, USA
| | - Laurent Houzet
- Molecular Virology Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD, USA ; Current address: INSERM U1085-IRSET, Universite de Rennes1, Institut Federatif de Recherche 140, Rennes, France
| | - Rakesh Kumar
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
| | - Ajit Kumar
- Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA
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Twyffels L, Gueydan C, Kruys V. Transportin-1 and Transportin-2: protein nuclear import and beyond. FEBS Lett 2014; 588:1857-68. [PMID: 24780099 DOI: 10.1016/j.febslet.2014.04.023] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Revised: 04/12/2014] [Accepted: 04/16/2014] [Indexed: 12/22/2022]
Abstract
Nearly 20 years after its identification as a new β-karyopherin mediating the nuclear import of the RNA-binding protein hnRNP A1, Transportin-1 is still commonly overlooked in comparison with its best known cousin, Importin-β. Transportin-1 is nonetheless a considerable player in nucleo-cytoplasmic transport. Over the past few years, significant progress has been made in the characterization of the nuclear localization signals (NLSs) that Transportin-1 recognizes, thereby providing the molecular basis of its diversified repertoire of cargoes. The recent discovery that mutations in the Transportin-dependent NLS of FUS cause mislocalization of this protein and result in amyotrophic lateral sclerosis illustrates the importance of Transportin-dependent import for human health. Besides, new functions of Transportin-1 are emerging in processes other than nuclear import. Here, we summarize what is known about Transportin-1 and the related β-karyopherin Transportin-2.
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Affiliation(s)
- Laure Twyffels
- Laboratoire de Biologie moléculaire du gène (CP300), Faculté des Sciences, Université Libre de Bruxelles (ULB), Belgium; Center for Microscopy and Molecular Imaging (CMMI), 6041 Gosselies, Belgium.
| | - Cyril Gueydan
- Laboratoire de Biologie moléculaire du gène (CP300), Faculté des Sciences, Université Libre de Bruxelles (ULB), Belgium
| | - Véronique Kruys
- Laboratoire de Biologie moléculaire du gène (CP300), Faculté des Sciences, Université Libre de Bruxelles (ULB), Belgium; Center for Microscopy and Molecular Imaging (CMMI), 6041 Gosselies, Belgium
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Jean-Philippe J, Paz S, Lu ML, Caputi M. A truncated hnRNP A1 isoform, lacking the RGG-box RNA binding domain, can efficiently regulate HIV-1 splicing and replication. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:251-8. [PMID: 24530421 DOI: 10.1016/j.bbagrm.2014.02.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 01/31/2014] [Accepted: 02/05/2014] [Indexed: 10/25/2022]
Abstract
Heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is one of the most abundant RNA binding proteins. hnRNP A1 is localized prevalently in the nucleus but it can relocate to the cytoplasm in response to specific stimuli shuttling between nuclear and cytoplasmic compartments. The cellular localization of this protein is regulated by a short C-terminus motif (M9) and other less defined sequences. The RNA binding specificity of this protein is dependent on multiple RNA binding domains (RBDs), which regulate its role in RNA processing and expression. hnRNP A1 plays multiple roles in gene expression by regulating the biogenesis and translation of messengers RNAs, the processing of miRNAs, affecting transcription and controlling telomere maintenance. The multiple functions of this protein correlate with diverse roles in genetic disease, cancer and the replication of viral pathogens. Utilizing a tagged hnRNP A1 deletion library we have shown that the three hnRNP A1 RBDs contribute to the prevalent nuclear distribution of the protein. Our data also indicate that a truncated form of the protein, lacking one of the RBDs, the RGG-box, can regulate splicing of a splicing reporter minigene and down-regulate replication of the HIV-1 virus with efficiency comparable to the wild-type protein. This functional hnRNP A1 deletion mutant is similar to a predicted hnRNP A1 isoform, which had not been previously experimentally characterized.
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Affiliation(s)
- Jacques Jean-Philippe
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA
| | - Sean Paz
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA
| | - Michael L Lu
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA
| | - Massimo Caputi
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA.
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Abstract
Classic nuclear shuttling is mediated by an importin-α∙β heterodimer that binds to cargoes containing a nuclear localization signal, and shuttles most nuclear proteins immediately after their translation. Aside from this canonical mechanism, kariopheryn-βs or β-like importins operate by binding to non-canonical nuclear localization signals to mediate translocation without the assistance of importin-α. The mechanism by which these components operate is much less understood and is currently under investigation. Recently, several β-like importins have been implicated in the stimulated nuclear translocation of signaling proteins. Here, we propose that this group of importins might be responsible for the swift nuclear shuttling of many proteins following various stimuli.
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Jean-Philippe J, Paz S, Caputi M. hnRNP A1: the Swiss army knife of gene expression. Int J Mol Sci 2013; 14:18999-9024. [PMID: 24065100 PMCID: PMC3794818 DOI: 10.3390/ijms140918999] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic cells express a large variety of RNA binding proteins (RBPs), with diverse affinities and specificities towards target RNAs. These proteins play a crucial role in almost every aspect of RNA biogenesis, expression and function. The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a complex and diverse family of RNA binding proteins. hnRNPs display multiple functions in the processing of heterogeneous nuclear RNAs into mature messenger RNAs. hnRNP A1 is one of the most abundant and ubiquitously expressed members of this protein family. hnRNP A1 plays multiple roles in gene expression by regulating major steps in the processing of nascent RNA transcripts. The transcription, splicing, stability, export through nuclear pores and translation of cellular and viral transcripts are all mechanisms modulated by this protein. The diverse functions played by hnRNP A1 are not limited to mRNA biogenesis, but extend to the processing of microRNAs, telomere maintenance and the regulation of transcription factor activity. Genomic approaches have recently uncovered the extent of hnRNP A1 roles in the development and differentiation of living organisms. The aim of this review is to highlight recent developments in the study of this protein and to describe its functions in cellular and viral gene expression and its role in human pathologies.
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Affiliation(s)
- Jacques Jean-Philippe
- Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Rd, Boca Raton, FL 33431, USA.
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Troakes C, Hortobágyi T, Vance C, Al-Sarraj S, Rogelj B, Shaw CE. Transportin 1 colocalization with Fused in Sarcoma (FUS) inclusions is not characteristic for amyotrophic lateral sclerosis-FUS confirming disrupted nuclear import of mutant FUS and distinguishing it from frontotemporal lobar degeneration with FUS inclusions. Neuropathol Appl Neurobiol 2013; 39:553-61. [PMID: 22934812 DOI: 10.1111/j.1365-2990.2012.01300.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS Transportin 1 (TNPO 1) is an abundant component of the Fused in Sarcoma (FUS)-immunopositive inclusions seen in a subgroup of frontotemporal lobar degeneration (FTLD-FUS). TNPO 1 has been shown to bind to the C-terminal nuclear localizing signal (NLS) of FUS and mediate its nuclear import. Amyotrophic lateral sclerosis (ALS)-linked C-terminal mutants disrupt TNPO 1 binding to the NLS and impair nuclear import in cell culture. If this held true for human ALS then we predicted that FUS inclusions in patients with C-terminal FUS mutations would not colocalize with TNPO 1. METHODS Expression of TNPO 1 and colocalization with FUS was studied in the frontal cortex of FTLD-FUS (n = 3) and brain and spinal cord of ALS-FUS (n = 3), ALS-C9orf72 (n = 3), sporadic ALS (n = 7) and controls (n = 7). Expression levels and detergent solubility of TNPO 1 was measured by Western blot. RESULTS Aggregates of TNPO 1 were abundant and colocalized with FUS inclusions in the cortex of all FTLD-FUS cases. In contrast, no TNPO 1-positive aggregates or FUS colocalization was evident in two-thirds, ALS-FUS cases and was rare in one ALS-FUS case. Nor were they present in C9orf72 or sporadic ALS. No increase in the levels of TNPO 1 was seen in Western blots of spinal cord tissues from all ALS cases compared with controls. CONCLUSIONS These findings confirm that C-terminal FUS mutations prevent TNPO 1 binding to the NLS, inhibiting nuclear import and promoting cytoplasmic aggregation. The presence of TNPO 1 in wild-type FUS aggregates in FTLD-FUS distinguishes the two pathologies and implicates different disease mechanisms.
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Affiliation(s)
- C Troakes
- KHP Centre for Neurodegeneration Research, Institute of Psychiatry Department of Clinical Neuropathology, King's College London, London, UK.
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Piazzon N, Schlotter F, Lefebvre S, Dodré M, Méreau A, Soret J, Besse A, Barkats M, Bordonné R, Branlant C, Massenet S. Implication of the SMN complex in the biogenesis and steady state level of the signal recognition particle. Nucleic Acids Res 2012; 41:1255-72. [PMID: 23221635 PMCID: PMC3553995 DOI: 10.1093/nar/gks1224] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Spinal muscular atrophy is a severe motor neuron disease caused by reduced levels of the ubiquitous Survival of MotoNeurons (SMN) protein. SMN is part of a complex that is essential for spliceosomal UsnRNP biogenesis. Signal recognition particle (SRP) is a ribonucleoprotein particle crucial for co-translational targeting of secretory and membrane proteins to the endoplasmic reticulum. SRP biogenesis is a nucleo-cytoplasmic multistep process in which the protein components, except SRP54, assemble with 7S RNA in the nucleolus. Then, SRP54 is incorporated after export of the pre-particle into the cytoplasm. The assembly factors necessary for SRP biogenesis remain to be identified. Here, we show that 7S RNA binds to purified SMN complexes in vitro and that SMN complexes associate with SRP in cellular extracts. We identified the RNA determinants required. Moreover, we report a specific reduction of 7S RNA levels in the spinal cord of SMN-deficient mice, and in a Schizosaccharomyces pombe strain carrying a temperature-degron allele of SMN. Additionally, microinjected antibodies directed against SMN or Gemin2 interfere with the association of SRP54 with 7S RNA in Xenopus laevis oocytes. Our data show that reduced levels of the SMN protein lead to defect in SRP steady-state level and describe the SMN complex as the first identified cellular factor required for SRP biogenesis.
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Affiliation(s)
- Nathalie Piazzon
- Laboratoire ARN-RNP structure-fonction-maturation, Enzymologie Moléculaire et Structurale (AREMS), Nancy Université-CNRS, UMR 7214, FR 3209, Faculté de Médecine de Nancy, BP 184, 9 avenue de la forêt de Haye, 54506 Vandoeuvre-les-Nancy Cedex, France
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Badding MA, Lapek JD, Friedman AE, Dean DA. Proteomic and functional analyses of protein-DNA complexes during gene transfer. Mol Ther 2012; 21:775-85. [PMID: 23164933 DOI: 10.1038/mt.2012.231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
One of the barriers to successful nonviral gene delivery is the crowded cytoplasm, which plasmids need to actively traverse for gene expression. Relatively little is known about how this process occurs, but our lab and others have shown that the microtubule network and motors are required for plasmid movement to the nucleus. To further investigate how plasmids exploit normal physiological processes to transfect cells, we have taken a proteomics approach to identify the proteins that comprise the plasmid-trafficking complex. We have developed a live cell DNA-protein pull-down assay to isolate complexes at certain time points post-transfection (15 minutes to 4 hours) for analysis by mass spectrometry (MS). Plasmids containing promoter sequences bound hundreds of unique proteins as early as 15 minutes post-electroporation, while a plasmid lacking any eukaryotic sequences failed to bind many of the proteins. Specific proteins included microtubule-based motor proteins (e.g., kinesin and dynein), proteins involved in protein nuclear import (e.g., importin 1, 2, 4, and 7, Crm1, RAN, and several RAN-binding proteins), a number of heterogeneous nuclear ribonucleoprotein (hnRNP)- and mRNA-binding proteins, and transcription factors. The significance of several of the proteins involved in protein nuclear localization and plasmid trafficking was determined by monitoring movement of microinjected fluorescently labeled plasmids via live cell particle tracking in cells following protein knockdown by small-interfering RNA (siRNA) or through the use of specific inhibitors. While importin β1 was required for plasmid trafficking and subsequent nuclear import, importin α1 played no role in microtubule trafficking but was required for optimal plasmid nuclear import. Surprisingly, the nuclear export protein Crm1 also was found to complex with the transfected plasmids and was necessary for plasmid trafficking along microtubules and nuclear import. Our results show that various proteins involved in nuclear import and export influence intracellular trafficking of plasmids and subsequent nuclear accumulation.
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Affiliation(s)
- Melissa A Badding
- Department of Pediatrics, Division of Neonatology, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
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Wang L, Li M, Cai M, Xing J, Wang S, Zheng C. A PY-nuclear localization signal is required for nuclear accumulation of HCMV UL79 protein. Med Microbiol Immunol 2012; 201:381-7. [PMID: 22628116 DOI: 10.1007/s00430-012-0243-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 05/08/2012] [Indexed: 01/19/2023]
Abstract
Human cytomegalovirus UL79 protein is recently reported to be required for transcription or efficient accumulation of late viral mRNAs during viral infection. An absolute nuclear distribution of UL79 proteins has been observed with immunofluorescence assay, both during the infection of Flag-tagged UL79 recombinant virus and in the HFFs expressing HA-tagged UL79, with or without virus infection. However, little is known about the nuclear import mechanism of UL79 protein. Here, by utilizing living cells fluorescent microscopy, a predominant nuclear localization of UL79 protein in living cells was detected. Furthermore, the nuclear import of UL79 protein was demonstrated to be dependent on the transportin-1-mediated pathway. Finally, a hydrophobic PY-nuclear localization signal (PY-NLS) was delineated between the amino acids 66-92 of UL79 protein. Collectively, we provide evidence that a PY-NLS, firstly described in viral proteins, is responsible for the nuclear accumulation of UL79 protein.
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Affiliation(s)
- Lin Wang
- Molecular Virology and Viral Immunology Research Group, State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, 44 Xiaohongshan, Wuchang, Wuhan, 430071, People's Republic of China
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Gomez Corredor A, Archambault D. The bovine immunodeficiency virus Rev protein: identification of a novel nuclear import pathway and nuclear export signal among retroviral Rev/Rev-like proteins. J Virol 2012; 86:4892-905. [PMID: 22379104 PMCID: PMC3347360 DOI: 10.1128/jvi.05132-11] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 02/22/2012] [Indexed: 01/11/2023] Open
Abstract
The Rev protein is essential for the replication of lentiviruses. Rev is a shuttling protein that transports unspliced and partially spliced lentiviral RNAs from the nucleus to the cytoplasm via the nucleopore. To transport these RNAs, the human immunodeficiency virus type 1 (HIV-1) Rev uses the karyopherin β family importin β and CRM1 proteins that interact with the Rev nuclear localization signal (NLS) and nuclear exportation signal (NES), respectively. Recently, we reported the presence of new types of bipartite NLS and nucleolar localization signal (NoLS) in the bovine immunodeficiency virus (BIV) Rev protein. Here we report the characterization of the nuclear import and export pathways of BIV Rev. By using an in vitro nuclear import assay, we showed that BIV Rev is transported into the nucleus by a cytosolic and energy-dependent importin α/β classical pathway. Results from glutathione S-transferase (GST) pulldown assays that showed the binding of BIV Rev with importins α3 and α5 were in agreement with those from the nuclear import assay. We also identified a leptomycin B-sensitive NES in BIV Rev, which indicates that the protein is exported via CRM1 like HIV-1 Rev. Mutagenesis experiments showed that the BIV Rev NES maps between amino acids 109 to 121 of the protein. Remarkably, the BIV Rev NES was found to be of the cyclic AMP (cAMP)-dependent protein kinase inhibitor (PKI) type instead of the HIV-1 Rev type. In summary, our data showed that the nuclear import mechanism of BIV Rev is novel among Rev proteins characterized so far in lentiviruses.
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Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol 2012; 86:7180-91. [PMID: 22514352 DOI: 10.1128/jvi.00541-12] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The Old World alphaviruses are emerging human pathogens with an ability to cause widespread epidemics. The latest epidemic of Chikungunya virus, from 2005 to 2007, affected over 40 countries in Africa, Asia, and Europe. The Old World alphaviruses are highly cytopathic and known to evade the cellular antiviral response by inducing global inhibition of transcription in vertebrate cells. This function was shown to be mediated by their nonstructural nsP2 protein; however, the detailed mechanism of this phenomenon has remained unknown. Here, we report that nsP2 proteins of Sindbis, Semliki Forest, and Chikungunya viruses inhibit cellular transcription by inducing rapid degradation of Rpb1, a catalytic subunit of the RNAPII complex. This degradation of Rpb1 is independent of the nsP2-associated protease activity, but, instead, it proceeds through nsP2-mediated Rpb1 ubiquitination. This function of nsP2 depends on the integrity of the helicase and S-adenosylmethionine (SAM)-dependent methyltransferase-like domains, and point mutations in either of these domains abolish Rpb1 degradation. We go on to show that complete degradation of Rpb1 in alphavirus-infected cells occurs within 6 h postinfection, before other previously described virus-induced changes in cell physiology, such as apoptosis, autophagy, and inhibition of STAT1 phosphorylation, are detected. Since Rpb1 is a subunit that catalyzes the polymerase reaction during RNA transcription, degradation of Rpb1 plays an indispensable role in blocking the activation of cellular genes and downregulating cellular antiviral response. This indicates that the nsP2-induced degradation of Rpb1 is a critical mechanism utilized by the Old World alphaviruses to subvert the cellular antiviral response.
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Lavi-Itzkovitz A, Tcherpakov M, Levy Z, Itzkovitz S, Muscatelli F, Fainzilber M. Functional consequences of necdin nucleocytoplasmic localization. PLoS One 2012; 7:e33786. [PMID: 22442722 PMCID: PMC3307762 DOI: 10.1371/journal.pone.0033786] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 02/19/2012] [Indexed: 02/02/2023] Open
Abstract
Background Necdin, a MAGE family protein expressed primarily in the nervous system, has been shown to interact with both nuclear and cytoplasmic proteins, but the mechanism of its nucleocytoplasmic transport are unknown. Methodology/Principal Findings We carried out a large-scale interaction screen using necdin as a bait in the yeast RRS system, and found a wide range of potential interactors with different subcellular localizations, including over 60 new candidates for direct binding to necdin. Integration of these interactions into a comprehensive network revealed a number of coherent interaction modules, including a cytoplasmic module connecting to necdin through huntingtin-associated protein 1 (Hap1), dynactin and hip-1 protein interactor (Hippi); a nuclear P53 and Creb-binding-protein (Crebbp) module, connecting through Crebbp and WW domain-containing transcription regulator protein 1 (Wwtr1); and a nucleocytoplasmic transport module, connecting through transportins 1 and 2. We validated the necdin-transportin1 interaction and characterized a sequence motif in necdin that modulates karyopherin interaction. Surprisingly, a D234P necdin mutant showed enhanced binding to both transportin1 and importin β1. Finally, exclusion of necdin from the nucleus triggered extensive cell death. Conclusions/Significance These data suggest that necdin has multiple roles within protein complexes in different subcellular compartments, and indicate that it can utilize multiple karyopherin-dependent pathways to modulate its localization.
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Affiliation(s)
- Anat Lavi-Itzkovitz
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Marianna Tcherpakov
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Zehava Levy
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Shalev Itzkovitz
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Francoise Muscatelli
- Institut de Neurobiologie de la Méditerranée, INSERM U901, Parc Scientifique de Luminy BP 13, Marseille, France
| | - Mike Fainzilber
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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Chung J, Khadka P, Chung IK. Nuclear import of hTERT requires a bipartite nuclear localization signal mediated by Akt phosphorylation. J Cell Sci 2012; 125:2684-97. [DOI: 10.1242/jcs.099267] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Sustained cell proliferation requires telomerase to maintain functional telomeres that are essential for chromosome integrity and protection. Although nuclear import of hTERT is required for telomerase activity to elongate telomeres in vivo, the molecular mechanism regulating nuclear localization of hTERT is unclear. Here we identify a bipartite nuclear localization signal (NLS) (amino acid residues 222–240) that is responsible for nuclear import of hTERT. Immunofluorescence imaging of hTERT revealed that mutations in any of the bipartite NLS sequences result in decreased nuclear fluorescence intensity compared to wild-type hTERT. We also show that Akt-mediated phosphorylation at serine 227 is necessary for directing nuclear translocation of hTERT. Interestingly, serine 227 is located between two clusters of basic amino acids in the bipartite NLS. Inactivation of Akt activity by a dominant-negative mutant or wortmannin treatment attenuated nuclear localization of hTERT. We further show that both bipartite NLS and serine 227 in hTERT are required for cellular immortalization of normal human foreskin fibroblast cells. Taken together, our findings reveal a novel regulatory mechanism of nuclear import of hTERT through a bipartite NLS mediated by Akt phosphorylation, which represents an alternative pathway for modulating telomerase activity in cancer.
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Chemical treatment enhances skipping of a mutated exon in the dystrophin gene. Nat Commun 2011; 2:308. [PMID: 21556062 PMCID: PMC3113229 DOI: 10.1038/ncomms1306] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 04/11/2011] [Indexed: 12/25/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal muscle wasting disease caused by a loss of the dystrophin protein. Control of dystrophin mRNA splicing to convert severe DMD to a milder phenotype is attracting much attention. Here we report a dystrophinopathy patient who has a point mutation in exon 31 of the dystrophin gene. Although the mutation generates a stop codon, a small amount of internally deleted, but functional, dystrophin protein is produced in the patient cells. An analysis of the mRNA reveals that the mutation promotes exon skipping and restores the open reading frame of dystrophin. Presumably, the mutation disrupts an exonic splicing enhancer and creates an exonic splicing silencer. Therefore, we searched for small chemicals that enhance exon skipping, and found that TG003 promotes the skipping of exon 31 in the endogenous dystrophin gene in a dose-dependent manner and increases the production of the dystrophin protein in the patient's cells. Duchenne muscular dystrophy is caused by a loss of the dystrophin gene, and control of dystrophin mRNA splicing could aid treatment of the disease. Nishida et al. show that a small molecule promotes skipping of exon 31 and increases production of a functional dystrophin protein in a patient.
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Kataoka N, Diem MD, Yoshida M, Hatai C, Dobashi I, Dreyfuss G, Hagiwara M, Ohno M. Specific Y14 domains mediate its nucleo-cytoplasmic shuttling and association with spliced mRNA. Sci Rep 2011; 1:92. [PMID: 22355610 PMCID: PMC3216578 DOI: 10.1038/srep00092] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 08/26/2011] [Indexed: 11/09/2022] Open
Abstract
Pre-mRNA splicing deposits multi-protein complexes, termed exon junction complexes (EJCs), on mRNAs near exon-exon junctions. The core of EJC consists of four proteins, eIF4AIII, MLN51, Y14 and Magoh. Y14 is a nuclear protein that can shuttle between the nucleus and the cytoplasm, and binds specifically to Magoh. Here we delineate a Y14 nuclear localization signal that also confers its nuclear export, which we name YNS. We further identified a 12-amino-acid peptide near Y14's carboxyl terminus that is required for its association with spliced mRNAs, as well as for Magoh binding. Furthermore, the Y14 mutants, which are deficient in binding to Magoh, could still be localized to the nucleus, suggesting the existence of both the nuclear import pathway and function for Y14 unaccompanied by Magoh.
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Affiliation(s)
- Naoyuki Kataoka
- Medical Top Track Program, Medical Research Institute, Tokyo Dental and Medical University, Tokyo 113-8510, Japan.
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Saitoh N, Oritani K, Saito K, Yokota T, Ichii M, Sudo T, Fujita N, Nakajima K, Okada M, Kanakura Y. Identification of functional domains and novel binding partners of STIM proteins. J Cell Biochem 2011; 112:147-56. [PMID: 21053360 DOI: 10.1002/jcb.22910] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
With a signal trap method, we previously identified stromal interaction molecule (STIM: originally named as SIM) as a protein, which has a signal peptide in 1996. However, recent works have accumulated evidences that STIM1 and STIM2 reside in endoplasmic reticulum (ER) and that both mainly sense ER Ca(2+) depletion, which plays an essential role in store operated calcium entry. In the present study, we extensively analyzed the domain functions and associated molecules of STIMs. A STIM1 mutant lacking the coiled-coil domains was massively expressed on the cell surface while mutants with the coiled-coil domains localized in ER. In addition, STIM1 mutants with the coiled-coil domains showed a longer half-life of proteins than those without them. These results are likely to indicate that the coiled-coil domains of STIM1 are essential for its ER-retention and its stability. Furthermore, we tried to comprehensively identify STIM1-associated molecules with mass spectrometry analysis of co-immunoprecipitated proteins for STIM1. This screening clarified that both STIM1 and STIM2 have a capacity to bind to a chaperone, calnexin as well as two protein-transporters, exportin1 and transportin1. Of importance, our result that glycosylation on STIM1 was not required for the association between STIM1 and calnexin seems to indicate that calnexin might function on STIM1 beyond a chaperone protein. Further information concerning regulatory mechanisms for STIM proteins including the data shown here will provide a model of Ca(2+) control as well as a useful strategy to develop therapeutic drugs for intracellular Ca(2+)-related diseases including inflammation and allergy.
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Affiliation(s)
- Norimitsu Saitoh
- Department of Hematology and Oncology, Graduate School of Medicine, Osaka University, Osaka, Japan
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Cherezova L, Burnside KL, Rose TM. Conservation of complex nuclear localization signals utilizing classical and non-classical nuclear import pathways in LANA homologs of KSHV and RFHV. PLoS One 2011; 6:e18920. [PMID: 21559489 PMCID: PMC3084728 DOI: 10.1371/journal.pone.0018920] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 03/23/2011] [Indexed: 11/18/2022] Open
Abstract
ORF73 latency-associated nuclear antigen (LANA) of the Kaposi's sarcoma-associated herpesvirus (KSHV) is targeted to the nucleus of infected cells where it binds to chromatin and mediates viral episome persistence, interacts with cellular proteins and plays a role in latency and tumorigenesis. A structurally related LANA homolog has been identified in the retroperitoneal fibromatosis herpesvirus (RFHV), the macaque homolog of KSHV. Here, we report the evolutionary and functional conservation of a novel bi-functional nuclear localization signal (NLS) in KSHV and RFHV LANA. N-terminal peptides from both proteins were fused to EGFP or double EGFP fusions to examine their ability to induce nuclear transport of a heterologous protein. In addition, GST-pull down experiments were used to analyze the ability of LANA peptides to interact with members of the karyopherin family of nuclear transport receptors. Our studies revealed that both LANA proteins contain an N-terminal arginine/glycine (RG)-rich domain spanning a conserved chromatin-binding motif, which binds directly to importin β1 in a RanGTP-sensitive manner and serves as an NLS in the importin β1-mediated non-classical nuclear import pathway. Embedded within this domain is a conserved lysine/arginine-(KR)-rich bipartite motif that binds directly to multiple members of the importin α family of nuclear import adaptors in a RanGTP-insensitive manner and serves as an NLS in the classical importin α/β-mediated nuclear import pathway. The positioning of a classical bipartite kr-NLS embedded within a non-classical rg-NLS is a unique arrangement in these viral proteins, whose nuclear localization is critical to their functionality and to the virus life cycle. The ability to interact with multiple import receptors provides alternate pathways for nuclear localization of LANA. Since different import receptors can import cargo to distinct subnuclear compartments, a multifunctional NLS may provide LANA with an increased ability to interact with different nuclear components in its multifunctional role to maintain viral latency.
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Affiliation(s)
- Lidia Cherezova
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
- Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America
| | - Kellie L. Burnside
- Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
| | - Timothy M. Rose
- Center for Childhood Infections and Prematurity Research, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Pediatrics, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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Sato M, Mizoro Y, Atobe Y, Fujimoto Y, Yamaguchi Y, Fustin JM, Doi M, Okamura H. Transportin 1 in the mouse brain: Appearance in regions of neurogenesis, cerebrospinal fluid production/sensing, and circadian clock. J Comp Neurol 2011; 519:1770-80. [DOI: 10.1002/cne.22600] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Hurd TW, Fan S, Margolis BL. Localization of retinitis pigmentosa 2 to cilia is regulated by Importin beta2. J Cell Sci 2011; 124:718-26. [PMID: 21285245 DOI: 10.1242/jcs.070839] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Ciliopathies represent a newly emerging group of human diseases that share a common etiology resulting from dysfunction of the cilium or centrosome. The gene encoding the retinitis pigmentosa 2 protein (RP2) is mutated in X-linked retinitis pigmentosa. RP2 localizes to the ciliary base and this requires the dual acylation of the N-terminus, but the precise mechanism by which RP2 is trafficked to the cilia is unknown. Here we have characterized an interaction between RP2 and Importin β2 (transportin-1), a member of the Importin-β family that regulates nuclear-cytoplasmic shuttling. We demonstrate that Importin β2 is necessary for localization of RP2 to the primary cilium because ablation of Importin β2 by shRNA blocks entry both of endogenous and exogenous RP2 to the cilium. Furthermore, we identify two distinct binding sites of RP2, which interact independently with Importin β2. One binding site is a nuclear localization signal (NLS)-like sequence that is located at the N-terminus of RP2 and the other is an M9-like sequence within the tubulin folding cofactor C (TBCC) domain. Mutation of the NLS-like consensus sequence did not abolish localization of RP2 to cilia, suggesting that the sequence is not essential for RP2 ciliary targeting. Interestingly, we found that several missense mutations that cause human disease fall within the M9-like sequence of RP2 and these mutations block entry of RP2 into the cilium, as well as its interaction with Importin β2. Together, this work further highlights a role of Importin β2 in regulation of the entry of RP2 and other proteins into the ciliary compartment.
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Affiliation(s)
- Toby W Hurd
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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