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Fare CM, Rothstein JD. Nuclear pore dysfunction and disease: a complex opportunity. Nucleus 2024; 15:2314297. [PMID: 38383349 PMCID: PMC10883112 DOI: 10.1080/19491034.2024.2314297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/30/2024] [Indexed: 02/23/2024] Open
Abstract
The separation of genetic material from bulk cytoplasm has enabled the evolution of increasingly complex organisms, allowing for the development of sophisticated forms of life. However, this complexity has created new categories of dysfunction, including those related to the movement of material between cellular compartments. In eukaryotic cells, nucleocytoplasmic trafficking is a fundamental biological process, and cumulative disruptions to nuclear integrity and nucleocytoplasmic transport are detrimental to cell survival. This is particularly true in post-mitotic neurons, where nuclear pore injury and errors to nucleocytoplasmic trafficking are strongly associated with neurodegenerative disease. In this review, we summarize the current understanding of nuclear pore biology in physiological and pathological contexts and discuss potential therapeutic approaches for addressing nuclear pore injury and dysfunctional nucleocytoplasmic transport.
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Affiliation(s)
- Charlotte M Fare
- Department of Neurology and Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Jeffrey D Rothstein
- Department of Neurology and Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
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2
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Malik SC, Lin JD, Ziegler-Waldkirch S, Tholen S, Deshpande SS, Schwabenland M, Schilling O, Vlachos A, Meyer-Luehmann M, Schachtrup C. Tpr Misregulation in Hippocampal Neural Stem Cells in Mouse Models of Alzheimer's Disease. Cells 2023; 12:2757. [PMID: 38067185 PMCID: PMC10706632 DOI: 10.3390/cells12232757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/19/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Nuclear pore complexes (NPCs) are highly dynamic macromolecular protein structures that facilitate molecular exchange across the nuclear envelope. Aberrant NPC functioning has been implicated in neurodegeneration. The translocated promoter region (Tpr) is a critical scaffolding nucleoporin (Nup) of the nuclear basket, facing the interior of the NPC. However, the role of Tpr in adult neural stem/precursor cells (NSPCs) in Alzheimer's disease (AD) is unknown. Using super-resolution (SR) and electron microscopy, we defined the different subcellular localizations of Tpr and phospho-Tpr (P-Tpr) in NSPCs in vitro and in vivo. Elevated Tpr expression and reduced P-Tpr nuclear localization accompany NSPC differentiation along the neurogenic lineage. In 5xFAD mice, an animal model of AD, increased Tpr expression in DCX+ hippocampal neuroblasts precedes increased neurogenesis at an early stage, before the onset of amyloid-β plaque formation. Whereas nuclear basket Tpr interacts with chromatin modifiers and NSPC-related transcription factors, P-Tpr interacts and co-localizes with cyclin-dependent kinase 1 (Cdk1) at the nuclear chromatin of NSPCs. In hippocampal NSPCs in a mouse model of AD, aberrant Tpr expression was correlated with altered NPC morphology and counts, and Tpr was aberrantly expressed in postmortem human brain samples from patients with AD. Thus, we propose that altered levels and subcellular localization of Tpr in CNS disease affect Tpr functionality, which in turn regulates the architecture and number of NSPC NPCs, possibly leading to aberrant neurogenesis.
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Affiliation(s)
- Subash C. Malik
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Jia-Di Lin
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Stephanie Ziegler-Waldkirch
- Department of Neurology, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (S.Z.-W.); (M.M.-L.)
| | - Stefan Tholen
- Institute of Surgical Pathology, Medical Center, University of Freiburg, 79106 Freiburg, Germany; (S.T.); (O.S.)
| | - Sachin S. Deshpande
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Marius Schwabenland
- Institute of Neuropathology, University of Freiburg, 79106 Freiburg, Germany
| | - Oliver Schilling
- Institute of Surgical Pathology, Medical Center, University of Freiburg, 79106 Freiburg, Germany; (S.T.); (O.S.)
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany;
- Center BrainLinks-BrainTools, University of Freiburg, 79110 Freiburg, Germany
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Melanie Meyer-Luehmann
- Department of Neurology, Medical Center, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany; (S.Z.-W.); (M.M.-L.)
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Christian Schachtrup
- Institute of Anatomy and Cell Biology, University of Freiburg, 79104 Freiburg, Germany; (S.C.M.); (J.-D.L.); (S.S.D.)
- Center for Basics in Neuromodulation (NeuroModul Basics), Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
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3
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Varberg JM, Unruh JR, Bestul AJ, Khan AA, Jaspersen SL. Quantitative analysis of nuclear pore complex organization in Schizosaccharomyces pombe. Life Sci Alliance 2022; 5:5/7/e202201423. [PMID: 35354597 PMCID: PMC8967992 DOI: 10.26508/lsa.202201423] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/11/2022] [Accepted: 03/14/2022] [Indexed: 01/06/2023] Open
Abstract
Characterization of nuclear pores in Schizosaccharomyces pombe identifies regions of heterogeneous NPC density and composition and shows that NPCs are excluded near the spindle pole body by Lem2-mediated centromere tethering. The number, distribution, and composition of nuclear pore complexes (NPCs) in the nuclear envelope varies between cell types and changes during cellular differentiation and in disease. To understand how NPC density and organization are controlled, we analyzed the NPC number and distribution in the fission yeast Schizosaccharomyces pombe using structured illumination microscopy. The small size of yeast nuclei, genetic features of fungi, and our robust image analysis pipeline allowed us to study NPCs in intact nuclei under multiple conditions. Our data revealed that NPC density is maintained across a wide range of nuclear sizes. Regions of reduced NPC density are observed over the nucleolus and surrounding the spindle pole body (SPB). Lem2-mediated tethering of the centromeres to the SPB is required to maintain NPC exclusion near SPBs. These findings provide a quantitative understanding of NPC number and distribution in S. pombe and show that interactions between the centromere and the nuclear envelope influences local NPC distribution.
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Affiliation(s)
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Andrew J Bestul
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Azqa A Khan
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO, USA .,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
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4
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Emerging Connections between Nuclear Pore Complex Homeostasis and ALS. Int J Mol Sci 2022; 23:ijms23031329. [PMID: 35163252 PMCID: PMC8835831 DOI: 10.3390/ijms23031329] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/17/2022] [Accepted: 01/20/2022] [Indexed: 12/26/2022] Open
Abstract
Developing effective treatments for neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) requires understanding of the underlying pathomechanisms that contribute to the motor neuron loss that defines the disease. As it causes the largest fraction of familial ALS cases, considerable effort has focused on hexanucleotide repeat expansions in the C9ORF72 gene, which encode toxic repeat RNA and dipeptide repeat (DPR) proteins. Both the repeat RNA and DPRs interact with and perturb multiple elements of the nuclear transport machinery, including shuttling nuclear transport receptors, the Ran GTPase and the nucleoporin proteins (nups) that build the nuclear pore complex (NPC). Here, we consider recent work that describes changes to the molecular composition of the NPC in C9ORF72 model and patient neurons in the context of quality control mechanisms that function at the nuclear envelope (NE). For example, changes to NPC structure may be caused by the dysregulation of a conserved NE surveillance pathway mediated by the endosomal sorting complexes required for the transport protein, CHMP7. Thus, these studies are introducing NE and NPC quality control pathways as key elements in a pathological cascade that leads to C9ORF72 ALS, opening entirely new experimental avenues and possibilities for targeted therapeutic intervention.
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5
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Lange J, Wood-Kaczmar A, Ali A, Farag S, Ghosh R, Parker J, Casey C, Uno Y, Kunugi A, Ferretti P, Andre R, Tabrizi SJ. Mislocalization of Nucleocytoplasmic Transport Proteins in Human Huntington's Disease PSC-Derived Striatal Neurons. Front Cell Neurosci 2021; 15:742763. [PMID: 34658796 PMCID: PMC8519404 DOI: 10.3389/fncel.2021.742763] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/09/2021] [Indexed: 11/17/2022] Open
Abstract
Huntington's disease (HD) is an inherited neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene (HTT). Disease progression is characterized by the loss of vulnerable neuronal populations within the striatum. A consistent phenotype across HD models is disruption of nucleocytoplasmic transport and nuclear pore complex (NPC) function. Here we demonstrate that high content imaging is a suitable method for detecting mislocalization of lamin-B1, RAN and RANGAP1 in striatal neuronal cultures thus allowing a robust, unbiased, highly powered approach to assay nuclear pore deficits. Furthermore, nuclear pore deficits extended to the selectively vulnerable DARPP32 + subpopulation neurons, but not to astrocytes. Striatal neuron cultures are further affected by changes in gene and protein expression of RAN, RANGAP1 and lamin-B1. Lowering total HTT using HTT-targeted anti-sense oligonucleotides partially restored gene expression, as well as subtly reducing mislocalization of proteins involved in nucleocytoplasmic transport. This suggests that mislocalization of RAN, RANGAP1 and lamin-B1 cannot be normalized by simply reducing expression of CAG-expanded HTT in the absence of healthy HTT protein.
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Affiliation(s)
- Jenny Lange
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Alison Wood-Kaczmar
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Aneesa Ali
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Sahar Farag
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Rhia Ghosh
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Jennifer Parker
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Caroline Casey
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Yumiko Uno
- Neuroscience Drug Discovery Unit, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Akiyoshi Kunugi
- Neuroscience Drug Discovery Unit, Takeda Pharmaceutical Company Limited, Fujisawa, Japan
| | - Patrizia Ferretti
- Stem Cell and Regenerative Medicine Section, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
| | - Ralph Andre
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Sarah J. Tabrizi
- Huntington’s Disease Centre, Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
- UK Dementia Research Institute, University College London, London, United Kingdom
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6
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Van Bergen NJ, Bell KM, Carey K, Gear R, Massey S, Murrell EK, Gallacher L, Pope K, Lockhart PJ, Kornberg A, Pais L, Walkiewicz M, Simons C, Wickramasinghe VO, White SM, Christodoulou J. Pathogenic variants in nucleoporin TPR (translocated promoter region, nuclear basket protein) cause severe intellectual disability in humans. Hum Mol Genet 2021; 31:362-375. [PMID: 34494102 DOI: 10.1093/hmg/ddab248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/10/2021] [Accepted: 08/23/2021] [Indexed: 01/16/2023] Open
Abstract
The nuclear pore complex (NPC) is a multi-protein complex that regulates the trafficking of macromolecules between the nucleus and cytoplasm. Genetic variants in components of the NPC have been shown to cause a range of neurological disorders, including intellectual disability and microcephaly. Translocated promoter region, nuclear basket protein (TPR) is a critical scaffolding element of the nuclear facing interior of the NPC. Here we present two siblings with biallelic variants in TPR who present with a phenotype of microcephaly, ataxia and severe intellectual disability. The variants result in a premature truncation variant, and a splice variant leading to a 12-amino acid deletion respectively. Functional analyses in patient fibroblasts demonstrate significantly reduced TPR levels, and decreased TPR-containing NPC density. A compensatory increase in total NPC levels was observed, and decreased global RNA intensity in the nucleus. The discovery of variants that partly disable TPR function provide valuable insight into this essential protein in human disease, and our findings suggest that TPR variants are the cause of the siblings' neurological disorder.
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Affiliation(s)
- Nicole J Van Bergen
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Katrina M Bell
- Bioinformatics, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, VIC, Australia
| | - Kirsty Carey
- RNA Biology and Cancer Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
| | - Russell Gear
- Victorian Clinical Genetics Services, Royal Children's Hospital, VIC, Australia
| | - Sean Massey
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Edward K Murrell
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Lyndon Gallacher
- Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, VIC, Australia
| | - Kate Pope
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Paul J Lockhart
- Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Andrew Kornberg
- Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Neurology Department, Royal Children's Hospital, Melbourne, Australia.,Neurosciences Research, Murdoch Children's Research Institute, Victoria, Australia
| | - Lynn Pais
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Marzena Walkiewicz
- Translational Genomics Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Cas Simons
- Victorian Clinical Genetics Services, Royal Children's Hospital, VIC, Australia.,Translational Genomics Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia
| | | | - Vihandha O Wickramasinghe
- RNA Biology and Cancer Laboratory, Peter MacCallum Cancer Centre, Melbourne, VIC, Australia.,Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Susan M White
- Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, VIC, Australia
| | - John Christodoulou
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Discipline of Child & Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
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7
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Serpe C, Monaco L, Relucenti M, Iovino L, Familiari P, Scavizzi F, Raspa M, Familiari G, Civiero L, D’Agnano I, Limatola C, Catalano M. Microglia-Derived Small Extracellular Vesicles Reduce Glioma Growth by Modifying Tumor Cell Metabolism and Enhancing Glutamate Clearance through miR-124. Cells 2021; 10:2066. [PMID: 34440835 PMCID: PMC8393731 DOI: 10.3390/cells10082066] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/26/2021] [Accepted: 08/06/2021] [Indexed: 12/12/2022] Open
Abstract
Brain homeostasis needs continuous exchange of intercellular information among neurons, glial cells, and immune cells, namely microglial cells. Extracellular vesicles (EVs) are active players of this process. All the cells of the body, including the brain, release at least two subtypes of EVs, the medium/large EVs (m/lEVs) and small EVs (sEVs). sEVs released by microglia play an important role in brain patrolling in physio-pathological processes. One of the most common and malignant forms of brain cancer is glioblastoma. Altered intercellular communications constitute a base for the onset and the development of the disease. In this work, we used microglia-derived sEVs to assay their effects in vitro on murine glioma cells and in vivo in a glioma model on C57BL6/N mice. Our findings indicated that sEVs carry messages to cancer cells that modify glioma cell metabolism, reducing lactate, nitric oxide (NO), and glutamate (Glu) release. sEVs affect Glu homeostasis, increasing the expression of Glu transporter Glt-1 on astrocytes. We demonstrated that these effects are mediated by miR-124 contained in microglia-released sEVs. The in vivo benefit of microglia-derived sEVs results in a significantly reduced tumor mass and an increased survival of glioma-bearing mice, depending on miR-124.
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Affiliation(s)
- Carmela Serpe
- Department of Physiology and Pharmacology, Sapienza University, 00185 Rome, Italy; (C.S.); (L.M.)
| | - Lucia Monaco
- Department of Physiology and Pharmacology, Sapienza University, 00185 Rome, Italy; (C.S.); (L.M.)
| | - Michela Relucenti
- Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, Sapienza University, 00185 Rome, Italy; (M.R.); (G.F.)
| | - Ludovica Iovino
- Department of Biology, University of Padova, 35131 Padova, Italy; (L.I.); (L.C.)
| | - Pietro Familiari
- Department of Human Neurosciences, Division of Neurosurgery, Sapienza University, 00185 Rome, Italy;
| | - Ferdinando Scavizzi
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotond, Italy; (F.S.); (M.R.)
| | - Marcello Raspa
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotond, Italy; (F.S.); (M.R.)
| | - Giuseppe Familiari
- Department of Anatomical, Histological, Forensic Medicine and Orthopedics Sciences, Sapienza University, 00185 Rome, Italy; (M.R.); (G.F.)
| | - Laura Civiero
- Department of Biology, University of Padova, 35131 Padova, Italy; (L.I.); (L.C.)
- IRCCS San Camillo Hospital, 30126 Venice, Italy
| | - Igea D’Agnano
- Institute of Biomedical Technologies, CNR, 20054 Segrate, Italy;
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Laboratory Affiliated to Istituto Pasteur Italia Fondazione Cenci Bolognetti, Sapienza University, 00185 Rome, Italy
- IRCCS Neuromed, 86077 Pozzilli, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University, 00185 Rome, Italy; (C.S.); (L.M.)
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8
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Friedman AK, Boeynaems S, Baker LA. Synthetic hydrogel mimics of the nuclear pore complex for the study of nucleocytoplasmic transport defects in C9orf72 ALS/FTD. Anal Bioanal Chem 2021; 414:525-532. [PMID: 34170347 DOI: 10.1007/s00216-021-03478-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/08/2021] [Accepted: 06/14/2021] [Indexed: 11/29/2022]
Abstract
Dipeptide repeats (DPRs) associated with C9orf72 repeat expansions perturb nucleocytoplasmic transport and are implicated in the pathogenesis of amyotrophic lateral sclerosis. We present a synthetic hydrogel platform that can be used to analyze aspects of the molecular interaction of dipeptide repeats and the phenylalanine-glycine (FG) phase of the nuclear pore complex (NPC). Hydrogel scaffolds composed of acrylamide and copolymerized with FG monomers are first formed to recapitulate key FG interactions found in the NPC. With labeled probes, we find evidence that toxic arginine-rich DPRs (poly-GR and poly-PR), but not the non-toxic poly-GP, target NPC hydrogel mimics and block selective entry of a key nuclear transport receptor, importin beta (Impβ). The ease with which these synthetic hydrogel mimics can be adjusted/altered makes them an invaluable tool to dissect complex molecular interactions that underlie cellular transport processes and their perturbation in disease.
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Affiliation(s)
- Alicia K Friedman
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA
| | - Steven Boeynaems
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, Indiana, 47405, USA.
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9
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The Nuclear Pore Complex and mRNA Export in Cancer. Cancers (Basel) 2020; 13:cancers13010042. [PMID: 33375634 PMCID: PMC7796397 DOI: 10.3390/cancers13010042] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/11/2020] [Accepted: 12/22/2020] [Indexed: 02/07/2023] Open
Abstract
Export of mRNAs from the nucleus to the cytoplasm is a key regulatory step in the expression of proteins. mRNAs are transported through the nuclear pore complex (NPC). Export of mRNAs responds to a variety of cellular stimuli and stresses. Revelations of the specific effects elicited by NPC components and associated co-factors provides a molecular basis for the export of selected RNAs, independent of bulk mRNA export. Aberrant RNA export has been observed in primary human cancer specimens. These cargo RNAs encode factors involved in nearly all facets of malignancy. Indeed, the NPC components involved in RNA export as well as the RNA export machinery can be found to be dysregulated, mutated, or impacted by chromosomal translocations in cancer. The basic mechanisms associated with RNA export with relation to export machinery and relevant NPC components are described. Therapeutic strategies targeting this machinery in clinical trials is also discussed. These findings firmly position RNA export as a targetable feature of cancer along with transcription and translation.
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10
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Boumendil C, Hari P, Olsen KCF, Acosta JC, Bickmore WA. Nuclear pore density controls heterochromatin reorganization during senescence. Genes Dev 2019; 33:144-149. [PMID: 30692205 PMCID: PMC6362808 DOI: 10.1101/gad.321117.118] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/04/2018] [Indexed: 12/12/2022]
Abstract
During oncogene-induced senescence (OIS), heterochromatin is lost from the nuclear periphery and forms internal senescence-associated heterochromatin foci (SAHFs). We show that an increased nuclear pore density during OIS is responsible for SAHF formation. In particular, the nucleoporin TPR is necessary for both formation and maintenance of SAHFs. Loss of SAHFs does not affect cell cycle arrest but abrogates the senescence-associated secretory phenotype-a program of inflammatory cytokine gene activation. Our results uncover a previously unknown role of nuclear pores in heterochromatin reorganization in mammalian nuclei and demonstrate the importance of heterochromatin organization for a specific gene activation program.
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Affiliation(s)
- Charlene Boumendil
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Priya Hari
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Karl C F Olsen
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Juan Carlos Acosta
- Cancer Research UK Edinburgh Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Wendy A Bickmore
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
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11
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McCloskey A, Ibarra A, Hetzer MW. Tpr regulates the total number of nuclear pore complexes per cell nucleus. Genes Dev 2018; 32:1321-1331. [PMID: 30228202 PMCID: PMC6169833 DOI: 10.1101/gad.315523.118] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/23/2018] [Indexed: 01/16/2023]
Abstract
In this study, McCloskey et al. investigated the underlying mechanisms that control how many nuclear transport channels are assembled into a given nuclear envelope. Their results show that depletion of the NPC basket protein Tpr, but not Nup153, dramatically increases the total NPC number in various cell types and provide insight into a critical role of the nucleoporin Tpr in coordinating signal transduction pathways during cell proliferation and the dynamic organization of the nucleus. The total number of nuclear pore complexes (NPCs) per nucleus varies greatly between different cell types and is known to change during cell differentiation and cell transformation. However, the underlying mechanisms that control how many nuclear transport channels are assembled into a given nuclear envelope remain unclear. Here, we report that depletion of the NPC basket protein Tpr, but not Nup153, dramatically increases the total NPC number in various cell types. This negative regulation of Tpr occurs via a phosphorylation cascade of extracellular signal-regulated kinase (ERK), the central kinase of the mitogen-activated protein kinase (MAPK) pathway. Tpr serves as a scaffold for ERK to phosphorylate the nucleoporin (Nup) Nup153, which is critical for early stages of NPC biogenesis. Our results reveal a critical role of the Nup Tpr in coordinating signal transduction pathways during cell proliferation and the dynamic organization of the nucleus.
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Affiliation(s)
- Asako McCloskey
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92130, USA
| | - Arkaitz Ibarra
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92130, USA
| | - Martin W Hetzer
- Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92130, USA
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12
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Protoparvovirus Knocking at the Nuclear Door. Viruses 2017; 9:v9100286. [PMID: 28974036 PMCID: PMC5691637 DOI: 10.3390/v9100286] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 12/20/2022] Open
Abstract
Protoparvoviruses target the nucleus due to their dependence on the cellular reproduction machinery during the replication and expression of their single-stranded DNA genome. In recent years, our understanding of the multistep process of the capsid nuclear import has improved, and led to the discovery of unique viral nuclear entry strategies. Preceded by endosomal transport, endosomal escape and microtubule-mediated movement to the vicinity of the nuclear envelope, the protoparvoviruses interact with the nuclear pore complexes. The capsids are transported actively across the nuclear pore complexes using nuclear import receptors. The nuclear import is sometimes accompanied by structural changes in the nuclear envelope, and is completed by intranuclear disassembly of capsids and chromatinization of the viral genome. This review discusses the nuclear import strategies of protoparvoviruses and describes its dynamics comprising active and passive movement, and directed and diffusive motion of capsids in the molecularly crowded environment of the cell.
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Hoang TV, Kizilyaprak C, Spehner D, Humbel BM, Schultz P. Automatic segmentation of high pressure frozen and freeze-substituted mouse retina nuclei from FIB-SEM tomograms. J Struct Biol 2017; 197:123-134. [DOI: 10.1016/j.jsb.2016.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 10/03/2016] [Accepted: 10/06/2016] [Indexed: 10/20/2022]
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Nuclear Import of Hepatitis B Virus Capsids and Genome. Viruses 2017; 9:v9010021. [PMID: 28117723 PMCID: PMC5294990 DOI: 10.3390/v9010021] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 02/07/2023] Open
Abstract
Hepatitis B virus (HBV) is an enveloped pararetrovirus with a DNA genome, which is found in an up to 36 nm-measuring capsid. Replication of the genome occurs via an RNA intermediate, which is synthesized in the nucleus. The virus must have thus ways of transporting its DNA genome into this compartment. This review summarizes the data on hepatitis B virus genome transport and correlates the finding to those from other viruses.
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Abstract
Protein turnover is an effective way of maintaining a functional proteome, as old and potentially damaged polypeptides are destroyed and replaced by newly synthesized copies. An increasing number of intracellular proteins, however, have been identified that evade this turnover process and instead are maintained over a cell's lifetime. This diverse group of long-lived proteins might be particularly prone to accumulation of damage and thus have a crucial role in the functional deterioration of key regulatory processes during ageing.
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Baltanás FC, Casafont I, Lafarga V, Weruaga E, Alonso JR, Berciano MT, Lafarga M. Purkinje cell degeneration in pcd mice reveals large scale chromatin reorganization and gene silencing linked to defective DNA repair. J Biol Chem 2011; 286:28287-302. [PMID: 21700704 DOI: 10.1074/jbc.m111.246041] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA repair protects neurons against spontaneous or disease-associated DNA damage. Dysfunctions of this mechanism underlie a growing list of neurodegenerative disorders. The Purkinje cell (PC) degeneration mutation causes the loss of nna1 expression and is associated with the postnatal degeneration of PCs. This PC degeneration dramatically affects nuclear architecture and provides an excellent model to elucidate the nuclear mechanisms involved in a whole array of neurodegenerative disorders. We used immunocytochemistry for histone variants and components of the DNA damage response, an in situ transcription assay, and in situ hybridization for telomeres to analyze changes in chromatin architecture and function. We demonstrate that the phosphorylation of H2AX, a DNA damage signal, and the trimethylation of the histone H4K20, a repressive mark, in extensive domains of genome are epigenetic hallmarks of chromatin in degenerating PCs. These histone modifications are associated with a large scale reorganization of chromatin, telomere clustering, and heterochromatin-induced gene silencing, all of them key factors in PC degeneration. Furthermore, ataxia telangiectasia mutated and 53BP1, two components of the DNA repair pathway, fail to be concentrated in the damaged chromatin compartments, even though the expression levels of their coding genes were slightly up-regulated. Although the mechanism by which Nna1 loss of function leads to PC neurodegeneration is undefined, the progressive accumulation of DNA damage in chromosome territories irreversibly compromises global gene transcription and seems to trigger PC degeneration and death.
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Affiliation(s)
- Fernando C Baltanás
- Laboratory of Neural Plasticity and Neurorepair, Institute for Neuroscience of Castilla y León, Universidad de Salamanca, E-37007 Salamanca, Spain
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Baltanás FC, Casafont I, Weruaga E, Alonso JR, Berciano MT, Lafarga M. Nucleolar disruption and cajal body disassembly are nuclear hallmarks of DNA damage-induced neurodegeneration in purkinje cells. Brain Pathol 2010; 21:374-88. [PMID: 21054627 DOI: 10.1111/j.1750-3639.2010.00461.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The Purkinje cell (PC) degeneration (pcd) phenotype results from mutation in nna1 gene and is associated with the degeneration and death of PCs during the postnatal life. Although the pcd mutation is a model of the ataxic mouse, it shares clinical and pathological characteristics of inherited human spinocerebellar ataxias. PC degeneration in pcd mice provides a useful neuronal system to study nuclear mechanisms involved in DNA damage-dependent neurodegeneration, particularly the contribution of nucleoli and Cajal bodies (CBs). Both nuclear structures are engaged in housekeeping functions for neuronal survival, the biogenesis of ribosomes and the maturation of snRNPs and snoRNPs required for pre-mRNA and pre-rRNA processing, respectively. In this study, we use ultrastructural analysis, in situ transcription assay and molecular markers for DNA damage, nucleoli and CB components to demonstrate that PC degeneration involves the progressive accumulation of nuclear DNA damage associated with disruption of nucleoli and CBs, disassembly of polyribosomes into monoribosomes, ribophagy and shut down of nucleolar and extranucleolar transcription. Microarray analysis reveals that four genes encoding repressors of nucleolar rRNA synthesis (p53, Rb, PTEN and SNF2) are upregulated in the cerebellum of pcd mice. Collectively, these data support that nucleolar and CB alterations are hallmarks of DNA damage-induced neurodegeneration.
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Affiliation(s)
- Fernando C Baltanás
- Laboratory of Neural Plasticity and Neurorepair, Institute for Neuroscience of Castilla y León, Universidad de Salamanca, Salamanca, Spain
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18
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Fedorenko OA, Marchenko SM. Spontaneously active ion channels of the nuclear envelope membrane. ACTA ACUST UNITED AC 2010. [DOI: 10.15407/fz56.05.095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Fedorenko O, Yarotskyy V, Duzhyy D, Marchenko S. The large-conductance ion channels in the nuclear envelope of central neurons. Pflugers Arch 2010; 460:1045-50. [DOI: 10.1007/s00424-010-0882-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Revised: 08/03/2010] [Accepted: 09/14/2010] [Indexed: 11/30/2022]
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Krull S, Dörries J, Boysen B, Reidenbach S, Magnius L, Norder H, Thyberg J, Cordes VC. Protein Tpr is required for establishing nuclear pore-associated zones of heterochromatin exclusion. EMBO J 2010; 29:1659-73. [PMID: 20407419 PMCID: PMC2876962 DOI: 10.1038/emboj.2010.54] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Accepted: 03/09/2010] [Indexed: 12/21/2022] Open
Abstract
Amassments of heterochromatin in somatic cells occur in close contact with the nuclear envelope (NE) but are gapped by channel- and cone-like zones that appear largely free of heterochromatin and associated with the nuclear pore complexes (NPCs). To identify proteins involved in forming such heterochromatin exclusion zones (HEZs), we used a cell culture model in which chromatin condensation induced by poliovirus (PV) infection revealed HEZs resembling those in normal tissue cells. HEZ occurrence depended on the NPC-associated protein Tpr and its large coiled coil-forming domain. RNAi-mediated loss of Tpr allowed condensing chromatin to occur all along the NE's nuclear surface, resulting in HEZs no longer being established and NPCs covered by heterochromatin. These results assign a central function to Tpr as a determinant of perinuclear organization, with a direct role in forming a morphologically distinct nuclear sub-compartment and delimiting heterochromatin distribution.
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Affiliation(s)
- Sandra Krull
- Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Julia Dörries
- Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Björn Boysen
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Sonja Reidenbach
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
| | - Lars Magnius
- Department of Virology, Swedish Institute for Infectious Disease Control, Solna, Sweden
| | - Helene Norder
- Department of Virology, Swedish Institute for Infectious Disease Control, Solna, Sweden
| | - Johan Thyberg
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Volker C Cordes
- Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
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Schmitz A, Schwarz A, Foss M, Zhou L, Rabe B, Hoellenriegel J, Stoeber M, Panté N, Kann M. Nucleoporin 153 arrests the nuclear import of hepatitis B virus capsids in the nuclear basket. PLoS Pathog 2010; 6:e1000741. [PMID: 20126445 PMCID: PMC2813275 DOI: 10.1371/journal.ppat.1000741] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Accepted: 12/28/2009] [Indexed: 12/14/2022] Open
Abstract
Virtually all DNA viruses including hepatitis B viruses (HBV) replicate their genome inside the nucleus. In non-dividing cells, the genome has to pass through the nuclear pore complexes (NPCs) by the aid of nuclear transport receptors as e.g. importin β (karyopherin). Most viruses release their genome in the cytoplasm or at the cytosolic face of the NPC, as the diameter of their capsids exceeds the size of the NPC. The DNA genome of HBV is derived from reverse transcription of an RNA pregenome. Genome maturation occurs in cytosolic capsids and progeny capsids can deliver the genome into the nucleus causing nuclear genome amplification. The karyophilic capsids are small enough to pass the NPC, but nuclear entry of capsids with an immature genome is halted in the nuclear basket on the nuclear side of the NPC, and the genome remains encapsidated. In contrast, capsids with a mature genome enter the basket and consequently liberate the genome. Investigating the difference between immature and mature capsids, we found that mature capsids had to disintegrate in order to leave the nuclear basket. The arrest of a karyophilic cargo at the nuclear pore is a rare phenomenon, which has been described for only very few cellular proteins participating in nuclear entry. We analyzed the interactions causing HBV capsid retention. By pull-down assays and partial siRNA depletion, we showed that HBV capsids directly interact with nucleoporin 153 (Nup153), an essential protein of the nuclear basket which participates in nuclear transport via importin β. The binding sites of importin β and capsids were shown to overlap but capsid binding was 150-fold stronger. In cellulo experiments using digitonin-permeabilized cells confirmed the interference between capsid binding and nuclear import by importin β. Collectively, our findings describe a unique nuclear import strategy not only for viruses but for all karyophilic cargos. Viral capsids facilitate protection of the enclosed viral genome and participate in the intracellular transport of the genome. At the site of replication capsids have to release the genome. The particular factors triggering genome liberation are not well understood. Like other karyophilic cargos, hepatitis B virus (HBV) capsids are transported through the nuclear pore using nuclear transport receptors of the importin ß superfamily. Unlike physiological cargos, HBV capsids become arrested within the nuclear basket, which is a filamentous structure on the nuclear side of the nuclear pore. Asking which interaction causes this unique strategy, we found that the capsids bind to a protein of the basket periphery, nucleoporin 153 (Nup153). The findings were confirmed in situ using digitonin-permeabilized cells that support physiological genome delivery into the nucleus. We observed that HBV capsids bound to Nup153 irrespective of the maturation of the encapsidated genome. But while capsids with an immature genome remained in arrested state, capsids with a mature genome disassembled and released their DNA.
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Affiliation(s)
- André Schmitz
- Institute of Medical Virology, Justus Liebig University, Giessen, Germany
| | - Alexandra Schwarz
- Institute of Medical Virology, Justus Liebig University, Giessen, Germany
| | - Michael Foss
- UMR-CNRS 5234 MCMP, Université Bordeaux 2, Bordeaux, France
| | - Lixin Zhou
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Birgit Rabe
- Institute of Medical Virology, Justus Liebig University, Giessen, Germany
| | | | - Miriam Stoeber
- UMR-CNRS 5234 MCMP, Université Bordeaux 2, Bordeaux, France
| | - Nelly Panté
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michael Kann
- Institute of Medical Virology, Justus Liebig University, Giessen, Germany
- UMR-CNRS 5234 MCMP, Université Bordeaux 2, Bordeaux, France
- * E-mail:
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Fedorenko EA, Dyzhii DE, Marchenko SM. Large-conductance cationic channels in the nuclear envelope of Purkinje neurons from the rat cerebellum. NEUROPHYSIOLOGY+ 2007. [DOI: 10.1007/s11062-007-0014-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Sheffield LG, Miskiewicz HB, Tannenbaum LB, Mirra SS. Nuclear pore complex proteins in Alzheimer disease. J Neuropathol Exp Neurol 2006; 65:45-54. [PMID: 16410748 DOI: 10.1097/01.jnen.0000195939.40410.08] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ultrastructural studies of neurofibrillary tangles in Alzheimer disease (AD) have demonstrated a close relationship between nuclear pores and the cytoplasmic paired helical filaments comprising the tangles, as well as nuclear irregularity in many tangle-bearing neurons; nuclear pore aggregation has been observed in nearby neurons. These observations prompted examination of the nuclear pore complex (NPC) and proteins critical to nucleocytoplasmic transport in neurons with and without tangles in AD and control cases. Light microscopic study of hippocampus and neocortex in AD and controls revealed that all nuclei were labeled by antibodies to NPC proteins, including the central transporter nucleoporin Nup62. Nucleoporin and tau label revealed significantly more nuclear irregularity in AD, often associated with neurofibrillary tangles. Double label of Nup62 with apoptotic markers (TUNEL and active caspase-3) and a cell-cycle protein (cyclin B1) revealed no clear relationship of nuclear irregularity to apoptosis or cell-cycle protein expression. However, cytoplasmic accumulation of nuclear transport factor 2 (NTF2), a protein that transports cargo from the cytoplasm into the nucleus, was observed in a subset of hippocampal neurons with and without tangles in AD but not control cases. Further investigation of the NPC and nucleocytoplasmic transport in AD is warranted.
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Affiliation(s)
- Lynette G Sheffield
- Department of Pathology, SUNY Downstate Medical Center, Brooklyn, New York, NY 11203, USA
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Abstract
Giardia Lamblia is a flagellar parasite possessing the unusual morphology of bearing two nuclei. New morphological observations on trophozoites and encysting Giardia nuclei using routine transmission electron microscopy, freeze fracture and cytochemistry are presented. Nuclear pores of both nuclei in the same cells were assessed on freeze-fracture replicas from different cell cycle phases, and compared. These techniques showed that (1) both nuclei in the same cell are distinct in nuclear pore number and distribution; (2) nuclear pore complexes are frequently clustered in nuclear envelope domains; (3) dividing nuclei display very few nuclear pores; (4) few ribosomes are found on the outer nuclear envelope of the trophozoite form; (5) nuclear membranes present spots of closely apposed membranes, which are different from the typical diaphragm nuclear pore complexes; (6) in addition to the nuclear pores, membrane blebs are also present in the nuclear envelope; (7) encysting cells show intranuclear inclusions, morphologically similar to the ESV (encystation-specific vesicles) and to the ER membranes, which may be the result of nuclear envelope folding. It is proposed that the two nuclei in Giardia are dissimilar in morphology and activity.
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Affiliation(s)
- Marlene Benchimol
- Universidade Santa Ursula, Rua Jornalista Orlando Dantas 59, CEP 222-31-010 Botafogo, Rio de Janeiro, Brazil.
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Villagrá NT, Berciano J, Altable M, Navascués J, Casafont I, Lafarga M, Berciano MT. PML bodies in reactive sensory ganglion neurons of the Guillain–Barré syndrome. Neurobiol Dis 2004; 16:158-68. [PMID: 15207273 DOI: 10.1016/j.nbd.2004.02.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Revised: 01/28/2004] [Accepted: 02/18/2004] [Indexed: 11/16/2022] Open
Abstract
Acute inflammatory demyelinating polyneuropathy (AIDP) is a type of Guillain-Barré syndrome (GBS) characterized by primary nerve demyelination sometimes with secondary axonal degeneration. Studies on the fine structure of dorsal root ganglia in AIDP are lacking. Our aim was to investigate the cytology and nuclear organization of primary sensory neurons in AIDP with axonal injury using ultrastructural and immunohistochemical analysis. The light cytology of the L5 dorsal ganglion showed the characteristic findings of neuronal axonal reaction. The organization of chromatin, nucleolus, Cajal bodies, and nuclear pores corresponded to transcriptionally active neurons. However, the hallmark of the nuclear response to axonal injury was the formation of numerous nuclear bodies (NBs; 6.37 +/- 0.6, in the AIDP, vs. 2.53 +/- 0.2, in the control, mean +/- SDM), identified as promyelocytic leukemia (PML) bodies by the presence of the protein PML. In addition to PML protein, nuclear bodies contained SUMO-1 and the transcriptional regulators CREB-binding protein (CBP) and glucocorticoid receptor (GR). The presence of proteasome 19S was also detected in some nuclear bodies. We suggest that neuronal PML bodies could regulate the nuclear concentration of active proteins, a process mediated by protein interactions with PML and SUMO-1 proteins. In the AIDP case, the proliferation of PML bodies may result from the overexpression of some nuclear proteins due to changes in gene expression associated with axonal injury.
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Affiliation(s)
- Nuria T Villagrá
- Department of Anatomy and Cell Biology, University Hospital Marqués de Valdecilla, Santander, Spain
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Monteiro RA, Henrique RM, Rocha E, Silva MW, Oliveira MH. Quantitative age-changes in endoplasmic reticulum and nucleus of cerebellar granule cells. Neurobiol Aging 2000; 21:97-105. [PMID: 10794854 DOI: 10.1016/s0197-4580(00)00104-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A stereological study was performed on cerebellar granule cells from rats 2 to 24 months of age (eight different ages, five animals per age group) to quantify age-related alterations in the rough endoplasmic reticulum (RER). The mean surface density and the mean total surface area of the nucleus, as well as the mean absolute volume of euchromatin per cell, were also estimated to examine whether or not these had quantitative relationships with the RER. The mean surface density and the mean total surface area of RER per cell changed significantly, attaining maximum values at 24 months of 1733 microm(2)/1000 microm(3) (0.06) and 64 microm(2) (0.03), respectively, (coefficients of variation in parentheses). The corresponding values at 2 months were 706 microm(2)/1000 microm(3) (0.20) and 26 microm(2) (0.24). The mean absolute volume of the euchromatin changed significantly, with a minimum value of 57 microm(3) (0.05) occurring at 21 months. We postulate that the increase in RER may be part of a mechanism that compensates for an age-related decrease in euchromatin. An increase in the RER network may improve intracellular transport of proteins, production of which is apparently diminished with aging. The increase may also compensate for the reported decrease in calcium buffer capacity of smooth endoplasmic reticulum.
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Affiliation(s)
- R A Monteiro
- Laboratory of Histology and Embryology, Institute of Biomedical Sciences, University of Oporto, Largo Professor Abel Salazar no. 2, 4099-003, Porto, Portugal.
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Folprecht G, Schneider S, Oberleithner H. Aldosterone activates the nuclear pore transporter in cultured kidney cells imaged with atomic force microscopy. Pflugers Arch 1996; 432:831-8. [PMID: 8772133 DOI: 10.1007/s004240050205] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Nuclear pore complexes (NPC), located in the nuclear envelope, functionally connect the cell nucleus with the cytoplasm and serve as a crucial pathway for macromolecule exchange. A Madin-Darby canine kidney (MDCK) clone that resembles principal cells of the collecting duct was shown recently to respond to sustained aldosterone exposure with a significant increase in the NPC number per nucleus. The present study elucidates the molecular nature of the NPC pathway and its regulation by aldosterone applying atomic force microscopy. We imaged individual NPC in situ and searched for a putative so-called transporter in the NPC centre. In aldosterone-depleted cells we found numerous macromolecules docked to individual NPC waiting for translocation into the nucleoplasm (standby mode=inactive pore). In contrast, in aldosterone-treated cells NPC were frequently found free of macromolecules, indicating that the translocation process kept pace with docking under hormone-stimulated conditions (transport mode=active pore). In the NPC centre we detected a ring-like structure with a central invagination. We assume that the ring is the putative transporter and that the invagination is the channel entrance used for translocation of macromolecules. Transporters were found in open and closed configurations. In conclusion, the results provide evidence for the existence of a nuclear transporter as part of the translocation machinery of an individual NPC. Aldosterone increases the activity of the nuclear transporter and thus facilitates steroid-mediated gene expression.
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Affiliation(s)
- G Folprecht
- Department of Physiology, University of Würzburg, Röntgenring 9, D-97070 Würzburg, Germany
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28
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Belmont AS, Bruce K. Visualization of G1 chromosomes: a folded, twisted, supercoiled chromonema model of interphase chromatid structure. J Cell Biol 1994; 127:287-302. [PMID: 7929576 PMCID: PMC2120203 DOI: 10.1083/jcb.127.2.287] [Citation(s) in RCA: 226] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We have used light microscopy and serial thin-section electron microscopy to visualize intermediates of chromosome decondensation during G1 progression in synchronized CHO cells. In early G1, tightly coiled 100-130-nm "chromonema" fibers are visualized within partially decondensed chromatin masses. Progression from early to middle G1 is accompanied by a progressive uncoiling and straightening of these chromonema fibers. Further decondensation in later G1 and early S phase results in predominantly 60-80-nm chromonema fibers that can be traced up to 2-3 microns in length as discrete fibers. Abrupt transitions in diameter from 100-130 to 60-80 nm along individual fibers are suggestive of coiling of the 60-80-nm chromonema fibers to form the thicker 100-130-nm chromonema fiber. Local unfolding of these chromonema fibers, corresponding to DNA regions tens to hundreds of kilobases in length, reveal more loosely folded and extended 30-nm chromatin fibers. Kinks and supercoils appear as prominent features at all observed levels of folding. These results are inconsistent with prevailing models of chromosome structure and, instead, suggest a folded chromonema model of chromosome structure.
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Affiliation(s)
- A S Belmont
- Department of Cell and Structural Biology, University of Illinois, Champaign-Urbana 61801
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Lafarga M, Berciano MT, Garcia-Segura LM. Freeze-fracture organization of chromatin and cytoplasm in neurons and astroglia of rat cerebellar cortex. JOURNAL OF NEUROCYTOLOGY 1991; 20:533-51. [PMID: 1919602 DOI: 10.1007/bf01215262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The cytology of the cell nucleus and cytoplasm of neurons and astroglia of the rat cerebellar cortex has been investigated by freeze-fracture electron microscopy. The main differential characteristics in the cytoplasm of the several cell types of the cerebellar cortex were: (1) the organization of endoplasmic reticulum elements, including special configurations of lamellar bodies and hypolemmal complexes, (2) the polarity, extension and arrangement of Golgi cisterns and associated tubulovesicular elements; (3) the connection pattern among different membrane-bounded cellular compartments; and (4) the architecture of endomembranes (i.e. presence of pits and fenestrations). In the nucleus, the main differential features were the the three-dimensional view of the nuclear envelope, the distribution of nuclear pores and the aggregation pattern of chromatin, visualized as clusters of nuclear particles in cross-fractures. The quantitative analysis of chromatin revealed four peaks of nuclear particle sizes (8, 12, 17 and 21 nm) that may correspond to variable degrees of coiling of the polynucleosomal chain in the chromatin fibre. Significant differences were observed in the proportion, numerical density and size distribution of aggregated nuclear particles in heterochromatin domains among the different cell types of the cerebellar cortex. The percentage of nuclear particles in aggregates varied from 10% in Purkinje cells to 64% in granule cells. Astrocytes and Bergmann glia showed intermediate values (about 40%). The percentage of nuclear particles in aggregates showed a significant (P less than 0.05) negative linear correlation with the nuclear volume, the number of pores per unit nuclear volume and the total number of pores per nucleus. In granule cells and astroglia, heterochromatin domains had a greater percentage of large nuclear particles (greater than 10 nm) than did euchromatin domains, whereas in interneurons, Purkinje and Golgi cells heterochromatin and euchromatin showed a similar proportion of large particles. Nuclear particles in euchromatin exhibited a similar pattern of distribution in all cerebellar cells.
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Affiliation(s)
- M Lafarga
- Department of Anatomy and Cell Biology, Faculty of Medicine, Cardenal Herrara Oria s/n, Santander, Spain
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Perez J, Hernandez P, Garcia-Segura LM. Estradiol increases the number of nuclear pores in the arcuate neurons of the rat hypothalamus. J Comp Neurol 1991; 303:225-32. [PMID: 2013637 DOI: 10.1002/cne.903030205] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Freeze-fracture replicas of hypothalamic arcuate neurons and of Purkinje and granule cells of the cerebellar cortex from adult female rats were assessed in order to test the possible influence of estradiol on nuclear pores. Rats were ovariectomized and injected either with estradiol or with vehicle. An additional group of rats in proestrus was also studied. Pore diameter was not affected by ovariectomy or estrogen treatment. In arcuate neurons, the number of nuclear pores per nuclear membrane area, the total number of pores per nucleus, and the percentage of nuclear pores arranged in clusters were decreased by ovariectomy and increased within 30 minutes after estradiol administration to ovariectomized rats. The effect of estradiol on nuclear pores was sustained for several days; the number of pores and the percentage of pores in clusters reverted to control values by 1 month after the hormonal treatment. None of the above mentioned changes was observed in Purkinje and granule cells of the cerebellar cortex. These results indicate that estradiol may modulate the number and distribution of nuclear pores in arcuate neurons and suggest that the modification of the ultrastructure of the nuclear envelope may be one of the first effects of gonadal steroids on target cells.
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Affiliation(s)
- J Perez
- Instituto Cajal, C.S.I.C., Madrid, Spain
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Caruncho HJ, Anadon R. Endothelial cells of the meningeal capillaries in the rainbow trout: a freeze-fracture study. J Morphol 1990; 206:327-32. [PMID: 19999828 DOI: 10.1002/jmor.1052060309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Meningeal capillaries are unfenestrated. They are made up of endothelial cells that have a pinocytotic caveolae density of 41+/- 11/micron (2) and 89 +/- 21/ micron(2) the abluminal and luminal sides respectively. The total density of intramembrane particles is not significantly different between the luminal and the abluminal membranes;however, the coefficients of partition are significantly different (P < 0.001).One or two strands of tight junctions occur between adjacent cells but no gap junctions nor desmosomes exist. The density of nuclear pores is less than 3.2/micron(2). An abundance of intermediate filaments and free vesicles, some of which are seriated, characterize the cytoplasm. The functional significance of these findings is discussed.
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Affiliation(s)
- H J Caruncho
- Department of Fundamental Biology, University of Santiago De Compostela, E-15706 Santiago de Compostela, Spain
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