1
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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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2
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Yang Y, Guo L, Chen L, Gong B, Jia D, Sun Q. Nuclear transport proteins: structure, function, and disease relevance. Signal Transduct Target Ther 2023; 8:425. [PMID: 37945593 PMCID: PMC10636164 DOI: 10.1038/s41392-023-01649-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 11/12/2023] Open
Abstract
Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.
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Affiliation(s)
- Yang Yang
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Lu Guo
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Lin Chen
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Bo Gong
- The Key Laboratory for Human Disease Gene Study of Sichuan Province and Department of Laboratory Medicine, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Pediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China.
| | - Qingxiang Sun
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, China.
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3
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Penzo A, Palancade B. Puzzling out nuclear pore complex assembly. FEBS Lett 2023; 597:2705-2727. [PMID: 37548888 DOI: 10.1002/1873-3468.14713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/12/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
Nuclear pore complexes (NPCs) are sophisticated multiprotein assemblies embedded within the nuclear envelope and controlling the exchanges of molecules between the cytoplasm and the nucleus. In this review, we summarize the mechanisms by which these elaborate complexes are built from their subunits, the nucleoporins, based on our ever-growing knowledge of NPC structural organization and on the recent identification of additional features of this process. We present the constraints faced during the production of nucleoporins, their gathering into oligomeric complexes, and the formation of NPCs within nuclear envelopes, and review the cellular strategies at play, from co-translational assembly to the enrolment of a panel of cofactors. Remarkably, the study of NPCs can inform our perception of the biogenesis of multiprotein complexes in general - and vice versa.
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Affiliation(s)
- Arianna Penzo
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Benoit Palancade
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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4
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Damizia M, Altieri L, Lavia P. Non-transport roles of nuclear import receptors: In need of the right balance. Front Cell Dev Biol 2022; 10:1041938. [PMID: 36438555 PMCID: PMC9686011 DOI: 10.3389/fcell.2022.1041938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/21/2022] [Indexed: 11/12/2023] Open
Abstract
Nuclear import receptors ensure the recognition and transport of proteins across the nuclear envelope into the nucleus. In addition, as diverse processes as mitosis, post-translational modifications at mitotic exit, ciliogenesis, and phase separation, all share a common need for regulation by nuclear import receptors - particularly importin beta-1 and importin beta-2/transportin - independent on nuclear import. In particular, 1) nuclear import receptors regulate the mitotic spindle after nuclear envelope breakdown, 2) they shield cargoes from unscheduled ubiquitination, regulating their timely proteolysis; 3) they regulate ciliary factors, crucial to cell communications and tissue architecture during development; and 4) they prevent phase separation of toxic proteins aggregates in neurons. The balance of nuclear import receptors to cargoes is critical in all these processes, albeit in opposite directions: overexpression of import receptors, as often found in cancer, inhibits cargoes and impairs downstream processes, motivating the therapeutic design of specific inhibitors. On the contrary, elevated expression is beneficial in neuronal contexts, where nuclear import receptors are regarded as potential therapeutic tools in counteracting the formation of aggregates that may cause neurodegeneration. This paradox demonstrates the amplitude of nuclear import receptors-dependent functions in different contexts and adds complexity in considering their therapeutic implications.
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Affiliation(s)
- Michela Damizia
- Department of Cellular, Computational and Integrated Biology (CIBIO), University of Trento, Trento, Italy
| | - Ludovica Altieri
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, Rome, Italy
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5
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Attenuated Viral Replication of Avian Infectious Bronchitis Virus with a Novel 82-Nucleotide Deletion in the 5a Gene Indicates a Critical Role for 5a in Virus-Host Interactions. Microbiol Spectr 2022; 10:e0140522. [PMID: 35766501 PMCID: PMC9430126 DOI: 10.1128/spectrum.01405-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously found that a deletion in γ-coronavirus Infectious bronchitis virus (IBV) accessory gene 5a is critical for decreased viral pathogenicity in chickens. Here, we systematically analyzed IBV virus infection: invasion, genome replication, subgenomic mRNA (sgmRNA) synthesis, protein synthesis, and virion release. The ability of the mutant IBV strain rYN-Δ5a to invade susceptible cells was not significantly different from that of parental rYN. However, compared with rYN, the level of sgmRNA synthesis and genome replication after cell entry by rYN-Δ5a was significantly lower in the early stage, resulting in a significantly lower level of nucleoprotein (N) synthesis and a consequent significantly lower number of offspring viruses released into the supernatant. The detected 5a protein was diffusely distributed in the cytoplasm and perinuclear area. We identified 16 differentially expressed host proteins, 8 of which were found to be host nuclear and cytoplasmic transport-related proteins. Coimmunoprecipitation revealed an interaction between hemagglutinin (HA)-tagged TNPO1, TNPO3, XPO1, XPOT, RanBP1, and EIF2B4 proteins and Flag-tagged 5a protein, and laser confocal microscopy confirmed 5a protein colocalization with these proteins, indicating that 5a protein can cause changes in the host protein localization. These host proteins promote the nuclear localization of N proteins, so we believe that 5a protein can hijack host nucleoplasmic transport-related proteins to help N enter the nucleus. This may involve regulating the cell cycle to promote the optimal intracellular conditions for virus assembly or by participating in the regulation of nucleolar function as a strategy to optimize virus replication. IMPORTANCE Coronaviruses (CoVs) have a huge impact on humans and animals. It is important for the prevention and control of the viruses to assess the molecular mechanisms related to virulence attenuation. Here, we systematically analyzed a single cycle of virus infection by γ-CoV IBV lacking accessory protein 5a. We observed that a 5a deletion in the IBV genome affected virus replication and sgmRNA synthesis early in the virus life cycle, leading to decreases in protein synthesis, offspring virus assembly, and virion release in chicken embryonic kidney cells. IBV 5a protein was found to interact with multiple host nuclear and cytoplasmic transport- and translation-related proteins, which can also interact with IBV N and relocate it into the cell nucleus. These findings provide a comprehensive view regarding the importance of IBV accessory protein 5a and an important theoretical basis for studying the interaction between coronavirus and host cell proteins.
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6
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Dultz E, Wojtynek M, Medalia O, Onischenko E. The Nuclear Pore Complex: Birth, Life, and Death of a Cellular Behemoth. Cells 2022; 11:1456. [PMID: 35563762 PMCID: PMC9100368 DOI: 10.3390/cells11091456] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/22/2022] [Accepted: 04/23/2022] [Indexed: 02/01/2023] Open
Abstract
Nuclear pore complexes (NPCs) are the only transport channels that cross the nuclear envelope. Constructed from ~500-1000 nucleoporin proteins each, they are among the largest macromolecular assemblies in eukaryotic cells. Thanks to advances in structural analysis approaches, the construction principles and architecture of the NPC have recently been revealed at submolecular resolution. Although the overall structure and inventory of nucleoporins are conserved, NPCs exhibit significant compositional and functional plasticity even within single cells and surprising variability in their assembly pathways. Once assembled, NPCs remain seemingly unexchangeable in post-mitotic cells. There are a number of as yet unresolved questions about how the versatility of NPC assembly and composition is established, how cells monitor the functional state of NPCs or how they could be renewed. Here, we review current progress in our understanding of the key aspects of NPC architecture and lifecycle.
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Affiliation(s)
- Elisa Dultz
- Institute of Biochemistry, Department of Biology, ETHZ Zurich, 8093 Zurich, Switzerland;
| | - Matthias Wojtynek
- Institute of Biochemistry, Department of Biology, ETHZ Zurich, 8093 Zurich, Switzerland;
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland;
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland;
| | - Evgeny Onischenko
- Department of Biological Sciences, University of Bergen, 5020 Bergen, Norway
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7
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Goodman LD, Cope H, Nil Z, Ravenscroft TA, Charng WL, Lu S, Tien AC, Pfundt R, Koolen DA, Haaxma CA, Veenstra-Knol HE, Wassink-Ruiter JSK, Wevers MR, Jones M, Walsh LE, Klee VH, Theunis M, Legius E, Steel D, Barwick KES, Kurian MA, Mohammad SS, Dale RC, Terhal PA, van Binsbergen E, Kirmse B, Robinette B, Cogné B, Isidor B, Grebe TA, Kulch P, Hainline BE, Sapp K, Morava E, Klee EW, Macke EL, Trapane P, Spencer C, Si Y, Begtrup A, Moulton MJ, Dutta D, Kanca O, Wangler MF, Yamamoto S, Bellen HJ, Tan QKG. TNPO2 variants associate with human developmental delays, neurologic deficits, and dysmorphic features and alter TNPO2 activity in Drosophila. Am J Hum Genet 2021; 108:1669-1691. [PMID: 34314705 PMCID: PMC8456166 DOI: 10.1016/j.ajhg.2021.06.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/27/2021] [Indexed: 12/11/2022] Open
Abstract
Transportin-2 (TNPO2) mediates multiple pathways including non-classical nucleocytoplasmic shuttling of >60 cargoes, such as developmental and neuronal proteins. We identified 15 individuals carrying de novo coding variants in TNPO2 who presented with global developmental delay (GDD), dysmorphic features, ophthalmologic abnormalities, and neurological features. To assess the nature of these variants, functional studies were performed in Drosophila. We found that fly dTnpo (orthologous to TNPO2) is expressed in a subset of neurons. dTnpo is critical for neuronal maintenance and function as downregulating dTnpo in mature neurons using RNAi disrupts neuronal activity and survival. Altering the activity and expression of dTnpo using mutant alleles or RNAi causes developmental defects, including eye and wing deformities and lethality. These effects are dosage dependent as more severe phenotypes are associated with stronger dTnpo loss. Interestingly, similar phenotypes are observed with dTnpo upregulation and ectopic expression of TNPO2, showing that loss and gain of Transportin activity causes developmental defects. Further, proband-associated variants can cause more or less severe developmental abnormalities compared to wild-type TNPO2 when ectopically expressed. The impact of the variants tested seems to correlate with their position within the protein. Specifically, those that fall within the RAN binding domain cause more severe toxicity and those in the acidic loop are less toxic. Variants within the cargo binding domain show tissue-dependent effects. In summary, dTnpo is an essential gene in flies during development and in neurons. Further, proband-associated de novo variants within TNPO2 disrupt the function of the encoded protein. Hence, TNPO2 variants are causative for neurodevelopmental abnormalities.
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Affiliation(s)
- Lindsey D Goodman
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Heidi Cope
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA
| | - Zelha Nil
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Thomas A Ravenscroft
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Wu-Lin Charng
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Shenzhao Lu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - An-Chi Tien
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Rolph Pfundt
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA, PO Box 9101, Nijmegen, the Netherlands
| | - David A Koolen
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525 GA, PO Box 9101, Nijmegen, the Netherlands
| | - Charlotte A Haaxma
- Department of Pediatric Neurology, Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, Geert Grooteplein Zuid 10, 6525 GA, PO Box 9101, the Netherlands
| | - Hermine E Veenstra-Knol
- Department of Genetics, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, the Netherlands
| | - Jolien S Klein Wassink-Ruiter
- Department of Genetics, University of Groningen, University Medical Center Groningen, 9713 GZ Groningen, the Netherlands
| | - Marijke R Wevers
- Department of Genetics, Radboud University Medical Center, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - Melissa Jones
- Houston Area Pediatric Neurology, 24514 Kingsland Blvd, Katy, TX 77494, USA
| | - Laurence E Walsh
- Department of Pediatric Neurology, Riley Hospital for Children, Indianapolis, IN 46202, USA
| | - Victoria H Klee
- Department of Pediatric Neurology, Riley Hospital for Children, Indianapolis, IN 46202, USA
| | - Miel Theunis
- Center for Human Genetics, University Hospital Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Eric Legius
- Department of Human Genetics, University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Dora Steel
- Molecular Neurosciences, Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK; Department of Neurology, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Katy E S Barwick
- Molecular Neurosciences, Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
| | - Manju A Kurian
- Molecular Neurosciences, Developmental Neurosciences, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK; Department of Neurology, Great Ormond Street Hospital, London WC1N 3JH, UK
| | - Shekeeb S Mohammad
- T.Y. Nelson Department of Neurology and Neurosurgery, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Kids Neuroscience Centre, The Children's Hospital at Westmead, Faculty of Medicine and Health, Sydney Medical School, University of Sydney, Sydney, Westmead, NSW 2145, Australia
| | - Russell C Dale
- T.Y. Nelson Department of Neurology and Neurosurgery, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Kids Neuroscience Centre, The Children's Hospital at Westmead, Faculty of Medicine and Health, Sydney Medical School, University of Sydney, Sydney, Westmead, NSW 2145, Australia
| | - Paulien A Terhal
- Department of Genetics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
| | - Ellen van Binsbergen
- Department of Genetics, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands
| | - Brian Kirmse
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Bethany Robinette
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS 39216, USA
| | - Benjamin Cogné
- Centre hospitalier universitaire (CHU) de Nantes, Service de Génétique Médicale, 9 quai Moncousu, 44093 Nantes, France; INSERM, CNRS, UNIV Nantes, Centre hospitalier universitaire (CHU) de Nantes, l'institut du thorax, 44007 Nantes, France
| | - Bertrand Isidor
- Centre hospitalier universitaire (CHU) de Nantes, Service de Génétique Médicale, 9 quai Moncousu, 44093 Nantes, France; INSERM, CNRS, UNIV Nantes, Centre hospitalier universitaire (CHU) de Nantes, l'institut du thorax, 44007 Nantes, France
| | - Theresa A Grebe
- Phoenix Children's Hospital, Phoenix, AZ 85016, USA; Department of Child Health, University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Peggy Kulch
- Phoenix Children's Hospital, Phoenix, AZ 85016, USA
| | - Bryan E Hainline
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Katherine Sapp
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Eva Morava
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Eric W Klee
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Clinical Genomics, Mayo Clinic, Rochester, MN 55905, USA
| | - Erica L Macke
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA
| | - Pamela Trapane
- University of Florida, College of Medicine, Jacksonville, Jacksonville, FL 32209, USA
| | - Christopher Spencer
- University of Florida, College of Medicine, Jacksonville, Jacksonville, FL 32209, USA
| | - Yue Si
- GeneDx, Gaithersburg, MD 20877, USA
| | | | - Matthew J Moulton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Debdeep Dutta
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Development, Disease Models & Therapeutics Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Queenie K-G Tan
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
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8
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Nord MS, Bernis C, Carmona S, Garland DC, Travesa A, Forbes DJ. Exportins can inhibit major mitotic assembly events in vitro: membrane fusion, nuclear pore formation, and spindle assembly. Nucleus 2021; 11:178-193. [PMID: 32762441 PMCID: PMC7540616 DOI: 10.1080/19491034.2020.1798093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Xenopus egg extracts are a powerful in vitro tool for studying complex biological processes, including nuclear reconstitution, nuclear membrane and pore assembly, and spindle assembly. Extracts have been further used to demonstrate a moonlighting regulatory role for nuclear import receptors or importins on these cell cycle assembly events. Here we show that exportins can also play a role in these events. Addition of Crm1, Exportin-t, or Exportin-5 decreased nuclear pore assembly in vitro. RanQ69L-GTP, a constitutively active form of RanGTP, ameliorated inhibition. Both Crm1 and Exportin-t inhibited fusion of nuclear membranes, again counteracted by RanQ69L-GTP. In mitotic extracts, Crm1 and Exportin-t negatively impacted spindle assembly. Pulldowns from the extracts using Crm1- or Exportin-t-beads revealed nucleoporins known to be essential for both nuclear pore and spindle assembly, with RanQ69L-GTP decreasing a subset of these target interactions. This study suggests a model where exportins, like importins, can regulate major mitotic assembly events.
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Affiliation(s)
- Matthew S Nord
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Cyril Bernis
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Sarah Carmona
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Dennis C Garland
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Anna Travesa
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
| | - Douglass J Forbes
- Section of Cell and Developmental Biology, Division of Biological Sciences 0347, University of California-San Diego , La Jolla, CA, USA
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9
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Dicks MDJ, Betancor G, Jimenez-Guardeño JM, Pessel-Vivares L, Apolonia L, Goujon C, Malim MH. Multiple components of the nuclear pore complex interact with the amino-terminus of MX2 to facilitate HIV-1 restriction. PLoS Pathog 2018; 14:e1007408. [PMID: 30496303 PMCID: PMC6264145 DOI: 10.1371/journal.ppat.1007408] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 10/15/2018] [Indexed: 12/13/2022] Open
Abstract
Human myxovirus resistance 2 (MX2/MXB) is an interferon-induced post-entry inhibitor of human immunodeficiency virus type-1 (HIV-1) infection. While the precise mechanism of viral inhibition remains unclear, MX2 is localized to the nuclear envelope, and blocks the nuclear import of viral cDNAs. The amino-terminus of MX2 (N-MX2) is essential for anti-viral function, and mutation of a triple arginine motif at residues 11 to 13 abrogates anti-HIV-1 activity. In this study, we sought to investigate the role of N-MX2 in anti-viral activity by identifying functionally relevant host-encoded interaction partners through yeast-two-hybrid screening. Remarkably, five out of seven primary candidate interactors were nucleoporins or nucleoporin-like proteins, though none of these candidates were identified when screening with a mutant RRR11-13A N-MX2 fragment. Interactions were confirmed by co-immunoprecipitation, and RNA silencing experiments in cell lines and primary CD4+ T cells demonstrated that multiple components of the nuclear pore complex and nuclear import machinery can impact MX2 anti-viral activity. In particular, the phenylalanine-glycine (FG) repeat containing cytoplasmic filament nucleoporin NUP214, and transport receptor transportin-1 (TNPO1) were consistently required for full MX2, and interferon-mediated, anti-viral function. Both proteins were shown to interact with the triple arginine motif, and confocal fluorescence microscopy revealed that their simultaneous depletion resulted in diminished MX2 accumulation at the nuclear envelope. We therefore propose a model whereby multiple components of the nuclear import machinery and nuclear pore complex help position MX2 at the nuclear envelope to promote MX2-mediated restriction of HIV-1. The movement of large molecules into the cell nucleus is regulated at specific sites within the nuclear envelope termed nuclear pores. To infect cells productively, human immunodeficiency virus type-1 (HIV-1) must traverse the nuclear envelope to enable integration of the viral DNA into the genomic DNA of host cells. We, and others, have previously identified a cell-encoded protein, human myxovirus resistance 2 (MX2), which is expressed upon initiation of an innate immune response and prevents accumulation of HIV-1 DNA within the nucleus, thus imposing a block to infection. Here, we reveal that components of the nuclear pore complex, and nuclear import machinery, are required for MX2-dependent inhibition of HIV-1 infection. We show that MX2, which is localized at the cytoplasmic face of the nuclear envelope, interacts with multiple protein components of the nuclear pore complex, as well as transport receptor transportin-1, via a functionally required triple arginine motif at its amino-terminus. We speculate that these interactions facilitate MX2-mediated inhibition of HIV-1 nuclear import by situating the protein at the nuclear envelope.
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Affiliation(s)
- Matthew D. J. Dicks
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Gilberto Betancor
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Jose M. Jimenez-Guardeño
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Lucie Pessel-Vivares
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Luis Apolonia
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Caroline Goujon
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
| | - Michael H. Malim
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, London, United Kingdom
- * E-mail:
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10
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Dekraker C, Boucher E, Mandato CA. Regulation and Assembly of Actomyosin Contractile Rings in Cytokinesis and Cell Repair. Anat Rec (Hoboken) 2018; 301:2051-2066. [PMID: 30312008 DOI: 10.1002/ar.23962] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 08/24/2018] [Accepted: 08/27/2018] [Indexed: 01/17/2023]
Abstract
Cytokinesis and single-cell wound repair both involve contractile assemblies of filamentous actin (F-actin) and myosin II organized into characteristic ring-like arrays. The assembly of these actomyosin contractile rings (CRs) is specified spatially and temporally by small Rho GTPases, which trigger local actin polymerization and myosin II contractility via a variety of downstream effectors. We now have a much clearer view of the Rho GTPase signaling cascade that leads to the formation of CRs, but some factors involved in CR positioning, assembly, and function remain poorly understood. Recent studies show that this regulation is multifactorial and goes beyond the long-established Ca2+ -dependent processes. There is substantial evidence that the Ca2+ -independent changes in cell shape, tension, and plasma membrane composition that characterize cytokinesis and single-cell wound repair also regulate CR formation. Elucidating the regulation and mechanistic properties of CRs is important to our understanding of basic cell biology and holds potential for therapeutic applications in human disease. In this review, we present a primer on the factors influencing and regulating CR positioning, assembly, and contraction as they occur in a variety of cytokinetic and single-cell wound repair models. Anat Rec, 301:2051-2066, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Corina Dekraker
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Eric Boucher
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
| | - Craig A Mandato
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada
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11
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Zhang K, Daigle JG, Cunningham KM, Coyne AN, Ruan K, Grima JC, Bowen KE, Wadhwa H, Yang P, Rigo F, Taylor JP, Gitler AD, Rothstein JD, Lloyd TE. Stress Granule Assembly Disrupts Nucleocytoplasmic Transport. Cell 2018; 173:958-971.e17. [PMID: 29628143 DOI: 10.1016/j.cell.2018.03.025] [Citation(s) in RCA: 250] [Impact Index Per Article: 41.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/08/2018] [Accepted: 03/06/2018] [Indexed: 01/21/2023]
Abstract
Defects in nucleocytoplasmic transport have been identified as a key pathogenic event in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mediated by a GGGGCC hexanucleotide repeat expansion in C9ORF72, the most common genetic cause of ALS/FTD. Furthermore, nucleocytoplasmic transport disruption has also been implicated in other neurodegenerative diseases with protein aggregation, suggesting a shared mechanism by which protein stress disrupts nucleocytoplasmic transport. Here, we show that cellular stress disrupts nucleocytoplasmic transport by localizing critical nucleocytoplasmic transport factors into stress granules, RNA/protein complexes that play a crucial role in ALS pathogenesis. Importantly, inhibiting stress granule assembly, such as by knocking down Ataxin-2, suppresses nucleocytoplasmic transport defects as well as neurodegeneration in C9ORF72-mediated ALS/FTD. Our findings identify a link between stress granule assembly and nucleocytoplasmic transport, two fundamental cellular processes implicated in the pathogenesis of C9ORF72-mediated ALS/FTD and other neurodegenerative diseases.
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Affiliation(s)
- Ke Zhang
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - J Gavin Daigle
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kathleen M Cunningham
- Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Alyssa N Coyne
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kai Ruan
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jonathan C Grima
- Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Kelly E Bowen
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Harsh Wadhwa
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Peiguo Yang
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA 92010, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Department of Cell and Molecular Biology, Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Jeffrey D Rothstein
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Brain Science Institute, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
| | - Thomas E Lloyd
- Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Cellular and Molecular Medicine Program, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
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12
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Otsuka S, Ellenberg J. Mechanisms of nuclear pore complex assembly - two different ways of building one molecular machine. FEBS Lett 2018; 592:475-488. [PMID: 29119545 PMCID: PMC6220763 DOI: 10.1002/1873-3468.12905] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 10/27/2017] [Accepted: 11/02/2017] [Indexed: 12/16/2022]
Abstract
The nuclear pore complex (NPC) mediates all macromolecular transport across the nuclear envelope. In higher eukaryotes that have an open mitosis, NPCs assemble at two points in the cell cycle: during nuclear assembly in late mitosis and during nuclear growth in interphase. How the NPC, the largest nonpolymeric protein complex in eukaryotic cells, self-assembles inside cells remained unclear. Recent studies have started to uncover the assembly process, and evidence has been accumulating that postmitotic and interphase NPC assembly use fundamentally different mechanisms; the duration, structural intermediates, and regulation by molecular players are different and different types of membrane deformation are involved. In this Review, we summarize the current understanding of these two modes of NPC assembly and discuss the structural and regulatory steps that might drive the assembly processes. We furthermore integrate understanding of NPC assembly with the mechanisms for rapid nuclear growth in embryos and, finally, speculate on the evolutionary origin of the NPC implied by the presence of two distinct assembly mechanisms.
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Affiliation(s)
- Shotaro Otsuka
- Cell Biology and Biophysics UnitEuropean Molecular Biology LaboratoryHeidelbergGermany
| | - Jan Ellenberg
- Cell Biology and Biophysics UnitEuropean Molecular Biology LaboratoryHeidelbergGermany
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13
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Abstract
The mitotic spindle has a crucial role in ensuring the accurate segregation of chromosomes into the two daughter cells during cell division, which is paramount for maintaining genome integrity. It is a self-organized and dynamic macromolecular structure that is constructed from microtubules, microtubule-associated proteins and motor proteins. Thirty years of research have led to the identification of centrosome-, chromatin- and microtubule-mediated microtubule nucleation pathways that each contribute to mitotic spindle assembly. Far from being redundant pathways, data are now emerging regarding how they function together to ensure the timely completion of mitosis. We are also beginning to comprehend the multiple mechanisms by which cells regulate spindle scaling. Together, this research has increased our understanding of how cells coordinate hundreds of proteins to assemble the dynamic, precise and robust structure that is the mitotic spindle.
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14
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Stelma T, Chi A, van der Watt PJ, Verrico A, Lavia P, Leaner VD. Targeting nuclear transporters in cancer: Diagnostic, prognostic and therapeutic potential. IUBMB Life 2016; 68:268-80. [PMID: 26970212 DOI: 10.1002/iub.1484] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 01/20/2016] [Indexed: 01/10/2023]
Abstract
The Karyopherin superfamily is a major class of soluble transport receptors consisting of both import and export proteins. The trafficking of proteins involved in transcription, cell signalling and cell cycle regulation among other functions across the nuclear membrane is essential for normal cellular functioning. However, in cancer cells, the altered expression or localization of nuclear transporters as well as the disruption of endogenous nuclear transport inhibitors are some ways in which the Karyopherin proteins are dysregulated. The value of nuclear transporters in the diagnosis, prognosis and treatment of cancer is currently being elucidated with recent studies highlighting their potential as biomarkers and therapeutic targets.
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Affiliation(s)
- Tamara Stelma
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Alicia Chi
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Pauline J van der Watt
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Annalisa Verrico
- Institute of Molecular Biology and Pathology, National Research Council of Italy, C/O University of Roma "La Sapienza", Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology, National Research Council of Italy, C/O University of Roma "La Sapienza", Rome, Italy
| | - Virna D Leaner
- Division of Medical Biochemistry, Department of Integrative Biomedical Sciences, SAMRC/UCT Gynaecological Cancer Research Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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15
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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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16
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Molliex A, Temirov J, Lee J, Coughlin M, Kanagaraj AP, Kim HJ, Mittag T, Taylor JP. Phase separation by low complexity domains promotes stress granule assembly and drives pathological fibrillization. Cell 2015; 163:123-33. [PMID: 26406374 PMCID: PMC5149108 DOI: 10.1016/j.cell.2015.09.015] [Citation(s) in RCA: 1726] [Impact Index Per Article: 191.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/05/2015] [Accepted: 08/25/2015] [Indexed: 02/07/2023]
Abstract
Stress granules are membrane-less organelles composed of RNA-binding proteins (RBPs) and RNA. Functional impairment of stress granules has been implicated in amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy-diseases that are characterized by fibrillar inclusions of RBPs. Genetic evidence suggests a link between persistent stress granules and the accumulation of pathological inclusions. Here, we demonstrate that the disease-related RBP hnRNPA1 undergoes liquid-liquid phase separation (LLPS) into protein-rich droplets mediated by a low complexity sequence domain (LCD). While the LCD of hnRNPA1 is sufficient to mediate LLPS, the RNA recognition motifs contribute to LLPS in the presence of RNA, giving rise to several mechanisms for regulating assembly. Importantly, while not required for LLPS, fibrillization is enhanced in protein-rich droplets. We suggest that LCD-mediated LLPS contributes to the assembly of stress granules and their liquid properties and provides a mechanistic link between persistent stress granules and fibrillar protein pathology in disease.
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Affiliation(s)
- Amandine Molliex
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jamshid Temirov
- Cell and Tissue Imaging Center, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jihun Lee
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Maura Coughlin
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Anderson P Kanagaraj
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Hong Joo Kim
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
| | - J Paul Taylor
- Howard Hughes Medical Institute, Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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17
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Heald R, Khodjakov A. Thirty years of search and capture: The complex simplicity of mitotic spindle assembly. J Cell Biol 2015; 211:1103-11. [PMID: 26668328 PMCID: PMC4687881 DOI: 10.1083/jcb.201510015] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 11/02/2015] [Indexed: 12/19/2022] Open
Abstract
Cell division is enacted by a microtubule-based, self-assembling macromolecular machine known as the mitotic spindle. In 1986, Kirschner and Mitchison proposed that by undergoing dynamic cycles of growth and disassembly, microtubules search for chromosomes. Capture of microtubules by the kinetochores progressively connects chromosomes to the bipolar spindle. 30 years later, “search and capture” remains the cornerstone of spindle assembly. However, a variety of facilitating mechanisms such as regulation of microtubule dynamics by diffusible gradients, spatially selective motor activities, and adaptive changes in chromosome architecture have been discovered. We discuss how these mechanisms ensure that the spindle assembles rapidly and with a minimal number of errors.
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Affiliation(s)
- Rebecca Heald
- Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Alexey Khodjakov
- Wadsworth Center, New York State Department of Health, Albany, NY 12201 Rensselaer Polytechnic Institute, Troy, NY 12180
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18
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Chen JWC, Barker AR, Wakefield JG. The Ran Pathway in Drosophila melanogaster Mitosis. Front Cell Dev Biol 2015; 3:74. [PMID: 26636083 PMCID: PMC4659922 DOI: 10.3389/fcell.2015.00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/09/2015] [Indexed: 11/29/2022] Open
Abstract
Over the last two decades, the small GTPase Ran has emerged as a central regulator of both mitosis and meiosis, particularly in the generation, maintenance, and regulation of the microtubule (MT)-based bipolar spindle. Ran-regulated pathways in mitosis bear many similarities to the well-characterized functions of Ran in nuclear transport and, as with transport, the majority of these mitotic effects are mediated through affecting the physical interaction between karyopherins and Spindle Assembly Factors (SAFs)—a loose term describing proteins or protein complexes involved in spindle assembly through promoting nucleation, stabilization, and/or depolymerization of MTs, through anchoring MTs to specific structures such as centrosomes, chromatin or kinetochores, or through sliding MTs along each other to generate the force required to achieve bipolarity. As such, the Ran-mediated pathway represents a crucial functional module within the wider spindle assembly landscape. Research into mitosis using the model organism Drosophila melanogaster has contributed substantially to our understanding of centrosome and spindle function. However, in comparison to mammalian systems, very little is known about the contribution of Ran-mediated pathways in Drosophila mitosis. This article sets out to summarize our understanding of the roles of the Ran pathway components in Drosophila mitosis, focusing on the syncytial blastoderm embryo, arguing that it can provide important insights into the conserved functions on Ran during spindle formation.
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Affiliation(s)
- Jack W C Chen
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Amy R Barker
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK ; Centre for Microvascular Research, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London London, UK
| | - James G Wakefield
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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19
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Abstract
The Karyopherin-β family of proteins mediates nuclear transport of macromolecules. Nuclear versus cytoplasmic localization of proteins is often suggested by the presence of NLSs (nuclear localization signals) or NESs (nuclear export signals). Import-Karyopherin-βs or Importins bind to NLSs in their protein cargos to transport them through nuclear pore complexes into the nucleus. Until recently, only two classes of NLS had been biochemically and structurally characterized: the classical NLS, which is recognized by the Importin-α/β heterodimer and the PY-NLS (proline-tyrosine NLS), which is recognized by Karyopherin-β2 or Transportin-1. Structures of two other Karyopherin-βs, Kap121 and Transportin-SR2, in complex with their respective cargos were reported for the first time recently, revealing two new distinct classes of NLSs. The present paper briefly describes the classical NLS, reviews recent literature on the PY-NLS and provides in-depth reviews of the two newly discovered classes of NLSs that bind Kap121p and Transportin-SR respectively.
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20
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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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21
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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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Christodoulou A, Yokoyama H. Purification of nuclear localization signal-containing proteins and its application to investigation of the mechanisms of the cell division cycle. Small GTPases 2015; 6:20-7. [PMID: 25862163 PMCID: PMC4601338 DOI: 10.4161/21541248.2014.978162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The GTP bound form of the Ran GTPase (RanGTP) in the nucleus promotes nuclear import of the proteins bearing nuclear localization signals (NLS). When nuclear envelopes break down during mitosis, RanGTP is locally produced around chromosomes and drives the assembly of the spindle early in mitosis and the nuclear envelope (NE) later. RanGTP binds to the heterodimeric nuclear transport receptor importin α/β and releases NLS proteins from the receptor. Liberated NLS proteins around chromosomes have been shown to play distinct, essential roles in spindle and NE assembly. Here we provide a highly specific protocol to purify NLS proteins from crude cell lysates. The pure NLS fraction is an excellent resource to investigate the NLS protein function and identify new mitotic regulators, uncovering fundamental mechanisms of the cell division cycle. It takes 2–3 days to obtain the NLS fraction.
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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: 85] [Impact Index Per Article: 8.5] [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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