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Lai C, Xu L, Dai S. The nuclear export protein exportin-1 in solid malignant tumours: From biology to clinical trials. Clin Transl Med 2024; 14:e1684. [PMID: 38783482 PMCID: PMC11116501 DOI: 10.1002/ctm2.1684] [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: 12/07/2023] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Exportin-1 (XPO1), a crucial protein regulating nuclear-cytoplasmic transport, is frequently overexpressed in various cancers, driving tumor progression and drug resistance. This makes XPO1 an attractive therapeutic target. Over the past few decades, the number of available nuclear export-selective inhibitors has been increasing. Only KPT-330 (selinexor) has been successfully used for treating haematological malignancies, and KPT-8602 (eltanexor) has been used for treating haematologic tumours in clinical trials. However, the use of nuclear export-selective inhibitors for the inhibition of XPO1 expression has yet to be thoroughly investigated in clinical studies and therapeutic outcomes for solid tumours. METHODS We collected numerous literatures to explain the efficacy of XPO1 Inhibitors in preclinical and clinical studies of a wide range of solid tumours. RESULTS In this review, we focus on the nuclear export function of XPO1 and results from clinical trials of its inhibitors in solid malignant tumours. We summarized the mechanism of action and therapeutic potential of XPO1 inhibitors, as well as adverse effects and response biomarkers. CONCLUSION XPO1 inhibition has emerged as a promising therapeutic strategy in the fight against cancer, offering a novel approach to targeting tumorigenic processes and overcoming drug resistance. SINE compounds have demonstrated efficacy in a wide range of solid tumours, and ongoing research is focused on optimizing their use, identifying response biomarkers, and developing effective combination therapies. KEY POINTS Exportin-1 (XPO1) plays a critical role in mediating nucleocytoplasmic transport and cell cycle. XPO1 dysfunction promotes tumourigenesis and drug resistance within solid tumours. The therapeutic potential and ongoing researches on XPO1 inhibitors in the treatment of solid tumours. Additional researches are essential to address safety concerns and identify biomarkers for predicting patient response to XPO1 inhibitors.
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Affiliation(s)
- Chuanxi Lai
- Department of Colorectal SurgerySir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhouChina
- Key Laboratory of Biotherapy of Zhejiang ProvinceHangzhouChina
| | - Lingna Xu
- Department of Colorectal SurgerySir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhouChina
- Key Laboratory of Biotherapy of Zhejiang ProvinceHangzhouChina
| | - Sheng Dai
- Department of Colorectal SurgerySir Run Run Shaw HospitalSchool of MedicineZhejiang UniversityHangzhouChina
- Key Laboratory of Biotherapy of Zhejiang ProvinceHangzhouChina
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2
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Newell S, van der Watt PJ, Leaner VD. Therapeutic targeting of nuclear export and import receptors in cancer and their potential in combination chemotherapy. IUBMB Life 2024; 76:4-25. [PMID: 37623925 PMCID: PMC10952567 DOI: 10.1002/iub.2773] [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: 03/29/2023] [Accepted: 07/03/2023] [Indexed: 08/26/2023]
Abstract
Systemic modalities are crucial in the management of disseminated malignancies and liquid tumours. However, patient responses and tolerability to treatment are generally poor and those that enter remission often return with refractory disease. Combination therapies provide a methodology to overcome chemoresistance mechanisms and address dose-limiting toxicities. A deeper understanding of tumorigenic processes at the molecular level has brought a targeted therapy approach to the forefront of cancer research, and novel cancer biomarkers are being identified at a rapid rate, with some showing potential therapeutic benefits. The Karyopherin superfamily of proteins is soluble receptors that mediate nucleocytoplasmic shuttling of proteins and RNAs, and recently, nuclear transport receptors have been recognized as novel anticancer targets. Inhibitors against nuclear export have been approved for clinical use against certain cancer types, whereas inhibitors against nuclear import are in preclinical stages of investigation. Mechanistically, targeting nucleocytoplasmic shuttling has shown to abrogate oncogenic signalling and restore tumour suppressor functions through nuclear sequestration of relevant proteins and mRNAs. Hence, nuclear transport inhibitors display broad spectrum anticancer activity and harbour potential to engage in synergistic interactions with a wide array of cytotoxic agents and other targeted agents. This review is focussed on the most researched nuclear transport receptors in the context of cancer, XPO1 and KPNB1, and highlights how inhibitors targeting these receptors can enhance the therapeutic efficacy of standard of care therapies and novel targeted agents in a combination therapy approach. Furthermore, an updated review on the therapeutic targeting of lesser characterized karyopherin proteins is provided and resistance to clinically approved nuclear export inhibitors is discussed.
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Affiliation(s)
- Stella Newell
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
| | - Pauline J. van der Watt
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
- Institute of Infectious Diseases and Molecular Medicine, University of Cape TownCape TownSouth Africa
| | - Virna D. Leaner
- Division of Medical Biochemistry and Structural Biology, Department of Integrative Biomedical Sciences, Faculty of Health SciencesUniversity of Cape TownCape TownSouth Africa
- UCT/SAMRC Gynaecological Cancer Research CentreUniversity of Cape TownCape TownSouth Africa
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Wong CH, Wingett SW, Qian C, Taliaferro JM, Ross-Thriepland D, Bullock SL. Genome-scale requirements for dynein-based trafficking revealed by a high-content arrayed CRISPR screen. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.01.530592. [PMID: 36909483 PMCID: PMC10002790 DOI: 10.1101/2023.03.01.530592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The cytoplasmic dynein-1 (dynein) motor plays a key role in cellular organisation by transporting a wide variety of cellular constituents towards the minus ends of microtubules. However, relatively little is known about how the biosynthesis, assembly and functional diversity of the motor is orchestrated. To address this issue, we have conducted an arrayed CRISPR loss-of-function screen in human cells using the distribution of dynein-tethered peroxisomes and early endosomes as readouts. From a guide RNA library targeting 18,253 genes, 195 validated hits were recovered and parsed into those impacting multiple dynein cargoes and those whose effects are restricted to a subset of cargoes. Clustering of high-dimensional phenotypic fingerprints generated from multiplexed images revealed co-functional genes involved in many cellular processes, including several candidate novel regulators of core dynein functions. Mechanistic analysis of one of these proteins, the RNA-binding protein SUGP1, provides evidence that it promotes cargo trafficking by sustaining functional expression of the dynein activator LIS1. Our dataset represents a rich source of new hypotheses for investigating microtubule-based transport, as well as several other aspects of cellular organisation that were captured by our high-content imaging.
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Affiliation(s)
- Chun Hao Wong
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
- Discovery Biology, Discovery Sciences, AstraZeneca, R&D, Cambridge, CB4 0WG, UK
- Current address: Wellcome Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK
| | - Steven W. Wingett
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
| | - Chen Qian
- Quantitative Biology, Discovery Sciences, AstraZeneca, R&D, Cambridge, CB4 0WG, UK
| | - J. Matthew Taliaferro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | | | - Simon L. Bullock
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, CB2 0QH, UK
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Otte K, Zhao K, Braun M, Neubauer A, Raifer H, Helmprobst F, Barrera FO, Nimsky C, Bartsch JW, Rusch T. Eltanexor Effectively Reduces Viability of Glioblastoma and Glioblastoma Stem-Like Cells at Nano-Molar Concentrations and Sensitizes to Radiotherapy and Temozolomide. Biomedicines 2022; 10:biomedicines10092145. [PMID: 36140245 PMCID: PMC9496210 DOI: 10.3390/biomedicines10092145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 11/29/2022] Open
Abstract
Current standard adjuvant therapy of glioblastoma multiforme (GBM) using temozolomide (TMZ) frequently fails due to therapy resistance. Thus, novel therapeutic approaches are highly demanded. We tested the therapeutic efficacy of the second-generation XPO1 inhibitor Eltanexor using assays for cell viability and apoptosis in GBM cell lines and GBM stem-like cells. For most GBM-derived cells, IC50 concentrations for Eltanexor were below 100 nM. In correlation with reduced cell viability, apoptosis rates were significantly increased. GBM stem-like cells presented a combinatorial effect of Eltanexor with TMZ on cell viability. Furthermore, pretreatment of GBM cell lines with Eltanexor significantly enhanced radiosensitivity in vitro. To explore the mechanism of apoptosis induction by Eltanexor, TP53-dependent genes were analyzed at the mRNA and protein level. Eltanexor caused induction of TP53-related genes, TP53i3, PUMA, CDKN1A, and PML on both mRNA and protein level. Immunofluorescence of GBM cell lines treated with Eltanexor revealed a strong accumulation of CDKN1A, and, to a lesser extent, of p53 and Tp53i3 in cell nuclei as a plausible mechanism for Eltanexor-induced apoptosis. From these data, we conclude that monotherapy with Eltanexor effectively induces apoptosis in GBM cells and can be combined with current adjuvant therapies to provide a more effective therapy of GBM.
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Affiliation(s)
- Katharina Otte
- Department of Neurosurgery, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
- Department of Hematology, Oncology & Immunology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Kai Zhao
- Department of Neurosurgery, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Madita Braun
- Department of Neurosurgery, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
- Department of Hematology, Oncology & Immunology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Andreas Neubauer
- Department of Hematology, Oncology & Immunology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Hartmann Raifer
- FACS Core Facility, Philipps University Marburg, Hans-Meerwein-Strasse 3, 35043 Marburg, Germany
| | - Frederik Helmprobst
- Department of Neuropathology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Felipe Ovalle Barrera
- Department of Neuropathology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Christopher Nimsky
- Department of Neurosurgery, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Jörg W. Bartsch
- Department of Neurosurgery, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
| | - Tillmann Rusch
- Department of Hematology, Oncology & Immunology, Philipps University Marburg, Baldingerstrasse, 35043 Marburg, Germany
- Correspondence: ; Tel.: +49-6421-58-65625
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Lagadec F, Carlon-Andres I, Ragues J, Port S, Wodrich H, Kehlenbach RH. CRM1 Promotes Capsid Disassembly and Nuclear Envelope Translocation of Adenovirus Independently of Its Export Function. J Virol 2022; 96:e0127321. [PMID: 34757845 PMCID: PMC8826800 DOI: 10.1128/jvi.01273-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 11/01/2021] [Indexed: 11/20/2022] Open
Abstract
After receptor-mediated endocytosis and endosomal escape, adenoviral capsids can travel via microtubule organizing centers to the nuclear envelope. Upon capsid disassembly, viral genome import into nuclei of interphase cells then occurs through nuclear pore complexes, involving the nucleoporins Nup214 and Nup358. Import also requires the activity of the classic nuclear export receptor CRM1, as it is blocked by the selective inhibitor leptomycin B. We have now used artificially enucleated as well as mitotic cells to analyze the role of an intact nucleus in different steps of the viral life cycle. In enucleated U2OS cells, viral capsids traveled to the microtubule organizing center, whereas their removal from this complex was blocked, suggesting that this step required nuclear factors. In mitotic cells, on the other hand, CRM1 promoted capsid disassembly and genome release, suggesting a role of this protein that does not require intact nuclear envelopes or nuclear pore complexes and is distinct from its function as a nuclear export receptor. Similar to enucleation, inhibition of CRM1 by leptomycin B also leads to an arrest of adenoviral capsids at the microtubule organizing center. In a small-scale screen using leptomycin B-resistant versions of CRM1, we identified a mutant, CRM1 W142A P143A, that is compromised with respect to adenoviral capsid disassembly in both interphase and mitotic cells. Strikingly, this mutant is capable of exporting cargo proteins out of the nucleus of living cells or digitonin-permeabilized cells, pointing to a role of the mutated region that is not directly linked to nuclear export. IMPORTANCE A role of nucleoporins and of soluble transport factors in adenoviral genome import into the nucleus of infected cells in interphase has previously been established. The nuclear export receptor CRM1 promotes genome import, but its precise function is not known. Using enucleated and mitotic cells, we showed that CRM1 does not simply function by exporting a crucial factor out of the nucleus that would then trigger capsid disassembly and genome import. Instead, CRM1 has an export-independent role, a notion that is also supported by a mutant, CRM1 W142A P143A, which is export competent but deficient in viral capsid disassembly, in both interphase and mitotic cells.
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Affiliation(s)
- Floriane Lagadec
- Department of Molecular Biology, Faculty of Medicine, Göttingen Center of Biosciences (GZMB), Georg-August-University Göttingen, Göttingen, Germany
- CNRS UMR 5234, Fundamental Microbiology and Pathogenicity, Université de Bordeaux, Bordeaux, France
| | - Irene Carlon-Andres
- CNRS UMR 5234, Fundamental Microbiology and Pathogenicity, Université de Bordeaux, Bordeaux, France
| | - Jessica Ragues
- CNRS UMR 5234, Fundamental Microbiology and Pathogenicity, Université de Bordeaux, Bordeaux, France
| | - Sarah Port
- Department of Molecular Biology, Faculty of Medicine, Göttingen Center of Biosciences (GZMB), Georg-August-University Göttingen, Göttingen, Germany
| | - Harald Wodrich
- CNRS UMR 5234, Fundamental Microbiology and Pathogenicity, Université de Bordeaux, Bordeaux, France
| | - Ralph H. Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, Göttingen Center of Biosciences (GZMB), Georg-August-University Göttingen, Göttingen, Germany
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Azizian NG, Li Y. XPO1-dependent nuclear export as a target for cancer therapy. J Hematol Oncol 2020; 13:61. [PMID: 32487143 PMCID: PMC7268335 DOI: 10.1186/s13045-020-00903-4] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/22/2020] [Indexed: 01/08/2023] Open
Abstract
Cellular homeostasis requires the proper nuclear-cytoplasmic partitioning of large molecules, which is often deregulated in cancer. XPO1 is an export receptor responsible for the nuclear-cytoplasmic transport of hundreds of proteins and multiple RNA species. XPO1 is frequently overexpressed and/or mutated in human cancers and functions as an oncogenic driver. Suppression of XPO1-mediated nuclear export, therefore, presents a unique therapeutic strategy. In this review, we summarize the physiological functions of XPO1 as well as the development of various XPO1 inhibitors and provide an update on the recent clinical trials of the SINE compounds. We also discuss potential future research directions on the molecular function of XPO1 and the clinical application of XPO1 inhibitors.
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Affiliation(s)
- Nancy G Azizian
- Center for Immunotherapy Research, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX, 77030, USA
- Department of Medicine, Weill Cornell Medical College, New York, NY, 10065, USA
| | - Yulin Li
- Center for Immunotherapy Research, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX, 77030, USA.
- Department of Medicine, Weill Cornell Medical College, New York, NY, 10065, USA.
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7
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Lewis RA, Li J, Allenby NEE, Errington J, Hayles J, Nurse P. Screening and purification of natural products from actinomycetes that affect the cell shape of fission yeast. J Cell Sci 2017; 130:3173-3185. [PMID: 28775153 PMCID: PMC5612171 DOI: 10.1242/jcs.194571] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 07/21/2017] [Indexed: 12/15/2022] Open
Abstract
This study was designed to identify bioactive compounds that alter the cellular shape of the fission yeast Schizosaccharomyces pombe by affecting functions involved in the cell cycle or cell morphogenesis. We used a multidrug-sensitive fission yeast strain, SAK950 to screen a library of 657 actinomycete bacteria and identified 242 strains that induced eight different major shape phenotypes in S. pombe. These include the typical cell cycle-related phenotype of elongated cells, and the cell morphology-related phenotype of rounded cells. As a proof of principle, we purified four of these activities, one of which is a novel compound and three that are previously known compounds, leptomycin B, streptonigrin and cycloheximide. In this study, we have also shown novel effects for two of these compounds, leptomycin B and cycloheximide. The identification of these four compounds and the explanation of the S. pombe phenotypes in terms of their known, or predicted bioactivities, confirm the effectiveness of this approach. Summary: A cell shape-based visual screen of S. pombe in the presence of actinomycete-derived bioactivities and an explanation for the phenotypes following identification of the compounds.
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Affiliation(s)
- Richard A Lewis
- Cell Cycle Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,Demuris Ltd, Newcastle Biomedicine Bioincubators, William Leech Building, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Juanjuan Li
- Cell Cycle Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Nicholas E E Allenby
- Demuris Ltd, Newcastle Biomedicine Bioincubators, William Leech Building, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Jeffery Errington
- Demuris Ltd, Newcastle Biomedicine Bioincubators, William Leech Building, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Jacqueline Hayles
- Cell Cycle Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Paul Nurse
- Cell Cycle Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
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Camus V, Miloudi H, Taly A, Sola B, Jardin F. XPO1 in B cell hematological malignancies: from recurrent somatic mutations to targeted therapy. J Hematol Oncol 2017; 10:47. [PMID: 28196522 PMCID: PMC5307790 DOI: 10.1186/s13045-017-0412-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/31/2017] [Indexed: 02/07/2023] Open
Abstract
Many recent publications highlight the large role of the pivotal eukaryotic nuclear export protein exportin-1 (XPO1) in the oncogenesis of several malignancies, and there is emerging evidence that XPO1 inhibition is a key target against cancer. The clinical validation of the pharmacological inhibition of XPO1 was recently achieved with the development of the selective inhibitor of nuclear export compounds, displaying an interesting anti-tumor activity in patients with massive pre-treated hematological malignancies. Recent reports have shown molecular alterations in the gene encoding XPO1 and showed a mutation hotspot (E571K) in the following two hematological malignancies with similar phenotypes and natural histories: primary mediastinal diffuse large B cell lymphoma and classical Hodgkin's lymphoma. Emerging evidence suggests that the mutant XPO1 E571K plays a role in carcinogenesis, and this variant is quantifiable in tumor and plasma cell-free DNA of patients using highly sensitive molecular biology techniques, such as digital PCR and next-generation sequencing. Therefore, it was proposed that the XPO1 E571K variant may serve as a minimal residual disease tool in this setting. To clarify and summarize the recent findings on the role of XPO1 in B cell hematological malignancies, we conducted a literature search to present the major publications establishing the landscape of XPO1 molecular alterations, their impact on the XPO1 protein, their interest as biomarkers, and investigations into the development of new XPO1-targeted therapies in B cell hematological malignancies.
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Affiliation(s)
- Vincent Camus
- Normandie Univ, INSERM U1245, UNICAEN, UNIROUEN, Caen, France
- Department of Hematology, Centre Henri Becquerel, Rouen, France
| | - Hadjer Miloudi
- Normandie Univ, INSERM U1245, UNICAEN, UNIROUEN, Caen, France
| | - Antoine Taly
- Laboratoire de Biochimie Théorique, Institut de Biologie Physico-Chimique, CNRS, Université Paris Diderot, Paris, France
| | - Brigitte Sola
- Normandie Univ, INSERM U1245, UNICAEN, UNIROUEN, Caen, France.
| | - Fabrice Jardin
- Normandie Univ, INSERM U1245, UNICAEN, UNIROUEN, Caen, France
- Department of Hematology, Centre Henri Becquerel, Rouen, France
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9
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Reaves DK, Hoadley KA, Fagan-Solis KD, Jima DD, Bereman M, Thorpe L, Hicks J, McDonald D, Troester MA, Perou CM, Fleming JM. Nuclear Localized LSR: A Novel Regulator of Breast Cancer Behavior and Tumorigenesis. Mol Cancer Res 2017; 15:165-178. [PMID: 27856957 PMCID: PMC5290211 DOI: 10.1158/1541-7786.mcr-16-0085-t] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 09/28/2016] [Accepted: 10/23/2016] [Indexed: 01/17/2023]
Abstract
Lipolysis-stimulated lipoprotein receptor (LSR) has been found in the plasma membrane and is believed to function in lipoprotein endocytosis and tight junctions. Given the impact of cellular metabolism and junction signaling pathways on tumor phenotypes and patient outcome, it is important to understand how LSR cellular localization mediates its functions. We conducted localization studies, evaluated DNA binding, and examined the effects of nuclear LSR in cells, xenografts, and clinical specimens. We found LSR within the membrane, cytoplasm, and the nucleus of breast cancer cells representing multiple intrinsic subtypes. Chromatin immunoprecipitation (ChIP) showed direct binding of LSR to DNA, and sequence analysis identified putative functional motifs and post-translational modifications of the LSR protein. While neither overexpression of transcript variants, nor pharmacologic manipulation of post-translational modification significantly altered localization, inhibition of nuclear export enhanced nuclear localization, suggesting a mechanism for nuclear retention. Coimmunoprecipitation and proximal ligation assays indicated LSR-pericentrin interactions, presenting potential mechanisms for nuclear-localized LSR. The clinical significance of LSR was evaluated using data from over 1,100 primary breast tumors, which showed high LSR levels in basal-like tumors and tumors from African-Americans. In tumors histosections, nuclear localization was significantly associated with poor outcomes. Finally, in vivo xenograft studies revealed that basal-like breast cancer cells that overexpress LSR exhibited both membrane and nuclear localization, and developed tumors with 100% penetrance, while control cells lacking LSR developed no tumors. These results show that nuclear LSR alters gene expression and may promote aggressive cancer phenotypes. IMPLICATIONS LSR functions in the promotion of aggressive breast cancer phenotypes and poor patient outcome via differential subcellular localization to alter cell signaling, bioenergetics, and gene expression. Mol Cancer Res; 15(2); 165-78. ©2016 AACR.
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Affiliation(s)
- Denise K Reaves
- Department of Biology, North Carolina Central University, Durham, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Katherine A Hoadley
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina
| | - Katerina D Fagan-Solis
- Department of Biology, North Carolina Central University, Durham, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Dereje D Jima
- Center for Human Health and the Environment, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Michael Bereman
- Center for Human Health and the Environment, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
| | - Lynnelle Thorpe
- Department of Biology, North Carolina Central University, Durham, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Jyla Hicks
- Department of Biology, North Carolina Central University, Durham, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - David McDonald
- Department of Biology, North Carolina Central University, Durham, North Carolina
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Melissa A Troester
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Charles M Perou
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Department of Genetics, University of North Carolina, Chapel Hill, North Carolina
| | - Jodie M Fleming
- Department of Biology, North Carolina Central University, Durham, North Carolina.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
- Center for Human Health and the Environment, Bioinformatics Research Center, North Carolina State University, Raleigh, North Carolina
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10
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Labarrade F, Botto JM, Domloge N. CRM1 and chromosomal passenger complex component survivin are essential to normal mitosis progress and to preserve keratinocytes from mitotic abnormalities. Int J Cosmet Sci 2016; 38:452-61. [PMID: 26859314 DOI: 10.1111/ics.12311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 02/04/2016] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Human epidermis provides the body a barrier against environmental assaults. To assume this function, the epidermis needs the renewal of keratinocytes allowed by constant mitosis, which replace the exfoliating corneocytes. Keratinocyte stem cells (KSCs) located in the basal epidermis are mitotically active, self-renewing and govern the epithelial stratification by producing renewed source of keratinocytes. Protein complex such as the chromosomal passenger complex (CPC) allows the correct development of this process. The CPC is composed of four members: INCENP, survivin, borealin and aurora kinase B, and the disruption of the CPC during cell division induces mitotic spindle defects and improper repartition of chromosomes. The aim of our study was to investigate the implication of CRM1 and survivin in the progress of mitosis in skin keratinocytes. METHODS Cultured human keratinocytes and skin biopsies were used in this study. KSCs-enriched population of keratinocytes was isolated from total keratinocytes by differential attachment to a type IV collagen matrix. Survivin and CRM1 expression levels were assessed by immunofluorescence and immunoblotting. Specific siRNAs for each CPC member and for CRM1 were used to determine the relationship between these proteins. Survivin-specific siRNA was used to induce the apparition of mitotic abnormalities in cultured keratinocytes. RESULTS We demonstrated the ability of our compound 'IV08.009' to modulate the expression level of survivin and CRM1 in keratinocytes and in skin biopsies. We observed that members of the CPC are interdependent: siRNA-induced inhibition of one component caused a decrease in the expression of all other CPC members. Downregulation of survivin or CRM1 induced mitotic abnormalities in keratinocytes. However, decreased number of mitotic abnormalities was observed in keratinocytes after 'IV08.009' application. CONCLUSION Basal keratinocytes may divide frequently during skin lifespan, and signs of deterioration could appear such as loss of protein factors required for correct mitosis. Our findings suggest that mitotic abnormalities can be prevented by the modulation of CRM1 and survivin. We demonstrated the ability of compound 'IV08.009' to efficiently protect cultured keratinocytes from mitotic abnormalities.
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Affiliation(s)
- F Labarrade
- Ashland Specialty Ingredients, Vincience Global Skin Research Center, 655, route du Pin Montard, 06904 Sophia Antipolis, France
| | - J-M Botto
- Ashland Specialty Ingredients, Vincience Global Skin Research Center, 655, route du Pin Montard, 06904 Sophia Antipolis, France.
| | - N Domloge
- Ashland Specialty Ingredients, Vincience Global Skin Research Center, 655, route du Pin Montard, 06904 Sophia Antipolis, France
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11
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Fernandes JD, Booth DS, Frankel AD. A structurally plastic ribonucleoprotein complex mediates post-transcriptional gene regulation in HIV-1. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:470-86. [PMID: 26929078 DOI: 10.1002/wrna.1342] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 01/28/2023]
Abstract
HIV replication requires the nuclear export of essential, intron-containing viral RNAs. To facilitate export, HIV encodes the viral accessory protein Rev which binds unspliced and partially spliced viral RNAs and creates a ribonucleoprotein complex that recruits the cellular Chromosome maintenance factor 1 export machinery. Exporting RNAs in this manner bypasses the necessity for complete splicing as a prerequisite for mRNA export, and allows intron-containing RNAs to reach the cytoplasm intact for translation and virus packaging. Recent structural studies have revealed that this entire complex exhibits remarkable plasticity at many levels of organization, including RNA folding, protein-RNA recognition, multimer formation, and host factor recruitment. In this review, we explore each aspect of plasticity from structural, functional, and possible therapeutic viewpoints. WIREs RNA 2016, 7:470-486. doi: 10.1002/wrna.1342 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Jason D Fernandes
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - David S Booth
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Alan D Frankel
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
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12
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Cavazza T, Vernos I. The RanGTP Pathway: From Nucleo-Cytoplasmic Transport to Spindle Assembly and Beyond. Front Cell Dev Biol 2016; 3:82. [PMID: 26793706 PMCID: PMC4707252 DOI: 10.3389/fcell.2015.00082] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 12/07/2015] [Indexed: 01/03/2023] Open
Abstract
The small GTPase Ran regulates the interaction of transport receptors with a number of cellular cargo proteins. The high affinity binding of the GTP-bound form of Ran to import receptors promotes cargo release, whereas its binding to export receptors stabilizes their interaction with the cargo. This basic mechanism linked to the asymmetric distribution of the two nucleotide-bound forms of Ran between the nucleus and the cytoplasm generates a switch like mechanism controlling nucleo-cytoplasmic transport. Since 1999, we have known that after nuclear envelope breakdown (NEBD) Ran and the above transport receptors also provide a local control over the activity of factors driving spindle assembly and regulating other aspects of cell division. The identification and functional characterization of RanGTP mitotic targets is providing novel insights into mechanisms essential for cell division. Here we review our current knowledge on the RanGTP system and its regulation and we focus on the recent advances made through the characterization of its mitotic targets. We then briefly review the novel functions of the pathway that were recently described. Altogether, the RanGTP system has moonlighting functions exerting a spatial control over protein interactions that drive specific functions depending on the cellular context.
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Affiliation(s)
- Tommaso Cavazza
- Cell and Developmental Biology, Centre for Genomic Regulation, The Barcelona Institute of Science and TechnologyBarcelona, Spain; Universitat Pompeu FabraBarcelona, Spain
| | - Isabelle Vernos
- Cell and Developmental Biology, Centre for Genomic Regulation, The Barcelona Institute of Science and TechnologyBarcelona, Spain; Universitat Pompeu FabraBarcelona, Spain; Institució Catalana de Recerca I Estudis AvançatsBarcelona, Spain
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13
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Abstract
Growing lines of evidence implicate the small GTPase RAN, its regulators and effectors--predominantly, nuclear transport receptors--in practically all aspects of centrosome biology in mammalian cells. These include duplication licensing, cohesion, positioning, and microtubule-nucleation capacity. RAN cooperates with the protein nuclear export vector exportin 1/CRM1 to recruit scaffolding proteins containing nuclear export sequences that play roles in the structural organization of centrosomes. Together, they also limit centrosome reduplication by regulating the localization of key "licensing" proteins during the centrosome duplication cycle. In parallel, RAN also regulates the capacity of centrosomes to nucleate and organize functional microtubules, and this predominanlty involves importin vectors: many factors regulating microtubule nucleation or function harbor nuclear localization sequences that interact with importin molecules and such interaction inhibits their activity. Active RANGTP binding to importin molecules removes the inhibition and releases microtubule regulatory factors in the free productive form. A dynamic scenario emerges, in which RAN is pivotal in linking spatiotemporal control of centrosome regulators to the cell cycle machinery.
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Affiliation(s)
- Patrizia Lavia
- Institute of Molecular Biology and Pathology, CNR National Research Council of Italy, c/o Sapienza University of Rome, via degli Apuli 4, Rome, 00185, Italy.
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14
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Forbes DJ, Travesa A, Nord MS, Bernis C. Reprint of "Nuclear transport factors: global regulation of mitosis". Curr Opin Cell Biol 2015. [PMID: 26196321 DOI: 10.1016/j.ceb.2015.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The unexpected repurposing of nuclear transport proteins from their function in interphase to an equally vital and very different set of functions in mitosis was very surprising. The multi-talented cast when first revealed included the import receptors, importin alpha and beta, the small regulatory GTPase RanGTP, and a subset of nuclear pore proteins. In this review, we report that recent years have revealed new discoveries in each area of this expanding story in vertebrates: (a) The cast of nuclear import receptors playing a role in mitotic spindle regulation has expanded: both transportin, a nuclear import receptor, and Crm1/Xpo1, an export receptor, are involved in different aspects of spindle assembly. Importin beta and transportin also regulate nuclear envelope and pore assembly. (b) The role of nucleoporins has grown to include recruiting the key microtubule nucleator – the γ-TuRC complex – and the exportin Crm1 to the mitotic kinetochores of humans. Together they nucleate microtubule formation from the kinetochores toward the centrosomes. (c) New research finds that the original importin beta/RanGTP team have been further co-opted by evolution to help regulate other cellular and organismal activities, ranging from the actual positioning of the spindle within the cell perimeter, to regulation of a newly discovered spindle microtubule branching activity, to regulation of the interaction of microtubule structures with specific actin structures. (d) Lastly, because of the multitudinous roles of karyopherins throughout the cell cycle, a recent large push toward testing their potential as chemotherapeutic targets has begun to yield burgeoning progress in the clinic.
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Affiliation(s)
- Douglass J Forbes
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States.
| | - Anna Travesa
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
| | - Matthew S Nord
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
| | - Cyril Bernis
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
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15
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Forbes DJ, Travesa A, Nord MS, Bernis C. Nuclear transport factors: global regulation of mitosis. Curr Opin Cell Biol 2015; 35:78-90. [PMID: 25982429 DOI: 10.1016/j.ceb.2015.04.012] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/01/2015] [Accepted: 04/17/2015] [Indexed: 12/22/2022]
Abstract
The unexpected repurposing of nuclear transport proteins from their function in interphase to an equally vital and very different set of functions in mitosis was very surprising. The multi-talented cast when first revealed included the import receptors, importin alpha and beta, the small regulatory GTPase RanGTP, and a subset of nuclear pore proteins. In this review, we report that recent years have revealed new discoveries in each area of this expanding story in vertebrates: (a) The cast of nuclear import receptors playing a role in mitotic spindle regulation has expanded: both transportin, a nuclear import receptor, and Crm1/Xpo1, an export receptor, are involved in different aspects of spindle assembly. Importin beta and transportin also regulate nuclear envelope and pore assembly. (b) The role of nucleoporins has grown to include recruiting the key microtubule nucleator - the γ-TuRC complex - and the exportin Crm1 to the mitotic kinetochores of humans. Together they nucleate microtubule formation from the kinetochores toward the centrosomes. (c) New research finds that the original importin beta/RanGTP team have been further co-opted by evolution to help regulate other cellular and organismal activities, ranging from the actual positioning of the spindle within the cell perimeter, to regulation of a newly discovered spindle microtubule branching activity, to regulation of the interaction of microtubule structures with specific actin structures. (d) Lastly, because of the multitudinous roles of karyopherins throughout the cell cycle, a recent large push toward testing their potential as chemotherapeutic targets has begun to yield burgeoning progress in the clinic.
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Affiliation(s)
- Douglass J Forbes
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States.
| | - Anna Travesa
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
| | - Matthew S Nord
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
| | - Cyril Bernis
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, Room 2124A Pacific Hall, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0347, United States
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16
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Mukherjee H, Chan KP, Andresen V, Hanley ML, Gjertsen BT, Myers AG. Interactions of the natural product (+)-avrainvillamide with nucleophosmin and exportin-1 Mediate the cellular localization of nucleophosmin and its AML-associated mutants. ACS Chem Biol 2015; 10:855-63. [PMID: 25531824 PMCID: PMC4652655 DOI: 10.1021/cb500872g] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nucleophosmin (NPM1) is a multifunctional phosphoprotein localized predominantly within the nucleoli of eukaryotic cells. Mutations within its C-terminal domain are frequently observed in patients with acute myeloid leukemia (AML), are thought to play a key role in the initiation of the disease, and result in aberrant, cytoplasmic localization of the mutant protein. We have previously shown that the electrophilic antiproliferative natural product (+)-avrainvillamide (1) binds to proteins, including nucleophosmin, by S-alkylation of cysteine residues. Here, we report that avrainvillamide restores nucleolar localization of certain AML-associated mutant forms of NPM1 and provide evidence that this relocalization is mediated by interactions of avrainvillamide with mutant NPM1 and exportin-1 (Crm1). Immunofluorescence and mass spectrometric experiments employing a series of different NPM1 constructs suggest that a specific interaction between avrainvillamide and Cys275 of certain NPM1 mutants mediates the relocalization of these proteins to the nucleolus. Avrainvillamide treatment is also shown to inhibit nuclear export of Crm1 cargo proteins, including AML-associated NPM1 mutants. We also observe that avrainvillamide treatment displaces Thr199-phosphorylated NPM1 from duplicated centrosomes, leads to an accumulation of supernumerary centrosomes, and inhibits dephosphorylation of Thr199-phosphorylated NPM1 by protein phosphatase 1. Avrainvillamide is the first small molecule reported to relocalize specific cytoplasmic AML-associated NPM1 mutants to the nucleolus, providing an important demonstration of principle that small molecule induction of a wild-type NPM1 localization phenotype is feasible in certain human cancer cells.
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Affiliation(s)
- Herschel Mukherjee
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Kok-Ping Chan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Vibeke Andresen
- Centre for Cancer Biomarkers, CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Mariah L. Hanley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Bjørn Tore Gjertsen
- Centre for Cancer Biomarkers, CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Internal Medicine, Hematology Section, Haukeland University Hospital, Bergen, Norway
| | - Andrew G. Myers
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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17
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Cunningham CN, Schmidt CA, Schramm NJ, Gaylord MR, Resendes KK. Human TREX2 components PCID2 and centrin 2, but not ENY2, have distinct functions in protein export and co-localize to the centrosome. Exp Cell Res 2013; 320:209-18. [PMID: 24291146 DOI: 10.1016/j.yexcr.2013.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 11/15/2022]
Abstract
TREX-2 is a five protein complex, conserved from yeast to humans, involved in linking mRNA transcription and export. The centrin 2 subunit of TREX-2 is also a component of the centrosome and is additionally involved in a distinctly different process of nuclear protein export. While centrin 2 is a known multifunctional protein, the roles of other human TREX-2 complex proteins other than mRNA export are not known. In this study, we found that human TREX-2 member PCID2 but not ENY2 is involved in some of the same cellular processes as those of centrin 2 apart from the classical TREX-2 function. PCID2 is present at the centrosome in a subset of HeLa cells and this localization is centrin 2 dependent. Furthermore, the presence of PCID2 at the centrosome is prevalent throughout the cell cycle as determined by co-staining with cyclins E, A and B. PCID2 but not ENY2 is also involved in protein export. Surprisingly, siRNA knockdown of PCID2 delayed the rate of nuclear protein export, a mechanism distinct from the effects of centrin 2, which when knocked down inhibits export. Finally we showed that co-depletion of centrin 2 and PCID2 leads to blocking rather than delaying nuclear protein export, indicating the dominance of the centrin 2 phenotype. Together these results represent the first discovery of specific novel functions for PCID2 other than mRNA export and suggest that components of the TREX-2 complex serve alternative shared roles in the regulation of nuclear transport and cell cycle progression.
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Affiliation(s)
- Corey N Cunningham
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Casey A Schmidt
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Nathaniel J Schramm
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA
| | - Michelle R Gaylord
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California - San Diego, 9500 Gilman Drive, #0347, La Jolla, CA 92093-0347, USA
| | - Karen K Resendes
- Westminster College, Department of Biology, 319 South Market Street, New Wilmington, PA 16172, USA.
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18
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Wu Z, Jiang Q, Clarke PR, Zhang C. Phosphorylation of Crm1 by CDK1-cyclin-B promotes Ran-dependent mitotic spindle assembly. J Cell Sci 2013; 126:3417-28. [PMID: 23729730 DOI: 10.1242/jcs.126854] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mitotic spindle assembly in animal cells is orchestrated by a chromosome-dependent pathway that directs microtubule stabilization. RanGTP generated at chromosomes releases spindle assembly factors from inhibitory complexes with importins, the nuclear transport factors that facilitate protein import into the nucleus during interphase. In addition, the nuclear export factor Crm1 has been proposed to act as a mitotic effector of RanGTP through the localized assembly of protein complexes on the mitotic spindle, notably at centrosomes and kinetochores. It has been unclear, however, how the functions of nuclear transport factors are controlled during mitosis. Here, we report that human Crm1 is phosphorylated at serine 391 in mitosis by CDK1-cyclin-B (i.e. the CDK1 and cyclin B complex). Expression of Crm1 with serine 391 mutated to either non-phosphorylated or phosphorylation-mimicking residues indicates that phosphorylation directs the localization of Crm1 to the mitotic spindle and facilitates spindle assembly, microtubule stabilization and chromosome alignment. We find that phosphorylation of Crm1 at serine 391 enhances its RanGTP-dependent interaction with RanGAP1-RanBP2 and promotes their recruitment to the mitotic spindle. These results show that phosphorylation of Crm1 controls its molecular interactions, localization and function during mitosis, uncovering a new mechanism for the control of mitotic spindle assembly by CDK1-cyclin-B. We propose that nuclear transport factors are controlled during mitosis through the selection of specific molecular interactions by protein phosphorylation.
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Affiliation(s)
- Zhige Wu
- The MOE Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering, College of Life Sciences, Peking University, Beijing 100871, China
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19
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Brodie KM, Henderson BR. Characterization of BRCA1 protein targeting, dynamics, and function at the centrosome: a role for the nuclear export signal, CRM1, and Aurora A kinase. J Biol Chem 2012; 287:7701-16. [PMID: 22262852 PMCID: PMC3293534 DOI: 10.1074/jbc.m111.327296] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/16/2012] [Indexed: 02/04/2023] Open
Abstract
BRCA1 is a DNA damage response protein and functions in the nucleus to stimulate DNA repair and at the centrosome to inhibit centrosome overduplication in response to DNA damage. The loss or mutation of BRCA1 causes centrosome amplification and abnormal mitotic spindle assembly in breast cancer cells. The BRCA1-BARD1 heterodimer binds and ubiquitinates γ-tubulin to inhibit centrosome amplification and promote microtubule nucleation; however regulation of BRCA1 targeting and function at the centrosome is poorly understood. Here we show that both N and C termini of BRCA1 are required for its centrosomal localization and that BRCA1 moves to the centrosome independently of BARD1 and γ-tubulin. Mutations in the C-terminal phosphoprotein-binding BRCT domain of BRCA1 prevented localization to centrosomes. Photobleaching experiments identified dynamic (60%) and immobilized (40%) pools of ectopic BRCA1 at the centrosome, and these are regulated by the nuclear export receptor CRM1 (chromosome region maintenance 1) and BARD1. CRM1 mediates nuclear export of BRCA1, and mutation of the export sequence blocked BRCA1 regulation of centrosome amplification in irradiated cells. CRM1 binds to undimerized BRCA1 and is displaced by BARD1. Photobleaching assays implicate CRM1 in driving undimerized BRCA1 to the centrosome and revealed that when BRCA1 subsequently binds to BARD1, it is less well retained at centrosomes, suggesting a mechanism to accelerate BRCA1 release after formation of the active heterodimer. Moreover, Aurora A binding and phosphorylation of BRCA1 enhanced its centrosomal retention and regulation of centrosome amplification. Thus, CRM1, BARD1 and Aurora A promote the targeting and function of BRCA1 at centrosomes.
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Affiliation(s)
- Kirsty M. Brodie
- From the Westmead Institute for Cancer Research, University of Sydney, Westmead Millennium Institute at Westmead Hospital, Darcy Road (P.O. Box 412), Westmead, New South Wales 2145, Australia
| | - Beric R. Henderson
- From the Westmead Institute for Cancer Research, University of Sydney, Westmead Millennium Institute at Westmead Hospital, Darcy Road (P.O. Box 412), Westmead, New South Wales 2145, Australia
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20
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Dückert H, Pries V, Khedkar V, Menninger S, Bruss H, Bird AW, Maliga Z, Brockmeyer A, Janning P, Hyman A, Grimme S, Schürmann M, Preut H, Hübel K, Ziegler S, Kumar K, Waldmann H. Natural product-inspired cascade synthesis yields modulators of centrosome integrity. Nat Chem Biol 2011; 8:179-84. [PMID: 22198731 DOI: 10.1038/nchembio.758] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 10/07/2011] [Indexed: 12/23/2022]
Abstract
In biology-oriented synthesis, the scaffolds of biologically relevant compound classes inspire the synthesis of focused compound collections enriched in bioactivity. This criterion is, in particular, met by the scaffolds of natural products selected in evolution. The synthesis of natural product-inspired compound collections calls for efficient reaction sequences that preferably combine multiple individual transformations in one operation. Here we report the development of a one-pot, twelve-step cascade reaction sequence that includes nine different reactions and two opposing kinds of organocatalysis. The cascade sequence proceeds within 10-30 min and transforms readily available substrates into complex indoloquinolizines that resemble the core tetracyclic scaffold of numerous polycyclic indole alkaloids. Biological investigation of a corresponding focused compound collection revealed modulators of centrosome integrity, termed centrocountins, which caused fragmented and supernumerary centrosomes, chromosome congression defects, multipolar mitotic spindles, acentrosomal spindle poles and multipolar cell division by targeting the centrosome-associated proteins nucleophosmin and Crm1.
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Affiliation(s)
- Heiko Dückert
- Max-Planck-Institut für Molekulare Physiologie, Abteilung Chemische Biologie, Dortmund, Germany
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