1
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Kakanj P, Bhide S, Moussian B, Leptin M. Autophagy-mediated plasma membrane removal promotes the formation of epithelial syncytia. EMBO J 2022; 41:e109992. [PMID: 35262206 PMCID: PMC9194749 DOI: 10.15252/embj.2021109992] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 02/08/2022] [Accepted: 02/10/2022] [Indexed: 01/18/2023] Open
Abstract
Epithelial wound healing in Drosophila involves the formation of multinucleate cells surrounding the wound. We show that autophagy, a cellular degradation process often deployed in stress responses, is required for the formation of a multinucleated syncytium during wound healing, and that autophagosomes that appear near the wound edge acquire plasma membrane markers. In addition, uncontrolled autophagy in the unwounded epidermis leads to the degradation of endo‐membranes and the lateral plasma membrane, while apical and basal membranes and epithelial barrier function remain intact. Proper functioning of TORC1 is needed to prevent destruction of the larval epidermis by autophagy, in a process that depends on phagophore initiation and expansion but does not require autophagosomes fusion with lysosomes. Autophagy induction can also affect other sub‐cellular membranes, as shown by its suppression of experimentally induced laminopathy‐like nuclear defects. Our findings reveal a function for TORC1‐mediated regulation of autophagy in maintaining membrane integrity and homeostasis in the epidermis and during wound healing.
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Affiliation(s)
- Parisa Kakanj
- Institute for Genetics, University of Cologne, Cologne, Germany.,Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
| | - Sourabh Bhide
- Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Faculty of Biosciences, Collaboration for Joint PhD degree between EMBL and Heidelberg University, Heidelberg, Germany
| | | | - Maria Leptin
- Institute for Genetics, University of Cologne, Cologne, Germany.,Director's Research Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany
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2
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Nanoscopic investigation of C9orf72 poly-GA oligomers on nuclear membrane disruption by a photoinducible platform. Commun Chem 2021; 4:111. [PMID: 36697556 PMCID: PMC9814621 DOI: 10.1038/s42004-021-00547-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/01/2021] [Indexed: 01/28/2023] Open
Abstract
Glycine-alanine dipeptide repeats (GA DPRs) translated from the mutated C9orf72 gene have recently been correlated with amyotrophic lateral sclerosis (ALS). While GA DPRs aggregates have been suggested as amyloid, the biophysical features and cytotoxicity of GA DPRs oligomers has not been explored due to its unstable nature. In this study, we develop a photoinducible platform based on methoxynitrobenzene chemistry to enrich GA DPRs that allows monitoring the oligomerization process of GA DPRs in cells. By applying advanced microscopies, we examined the GA DPRs oligomerization process nanoscopically in a time-dependent manner. We provided direct evidences to demonstrate GA DPRs oligomers rather than nanofibrils disrupt nuclear membrane. Moreover, we found GA DPRs hamper nucleocytoplasmic transport in cells and cause cytosolic retention of TAR DNA-binding protein 43 in cortical neurons. Our results highlight the toxicity of GA DPRs oligomers, which is a key step toward elucidating the pathological roles of C9orf72 DPRs.
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3
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Liebman C, McColloch A, Rabiei M, Bowling A, Cho M. Mechanics of the cell: Interaction mechanisms and mechanobiological models. CURRENT TOPICS IN MEMBRANES 2020; 86:143-184. [PMID: 33837692 DOI: 10.1016/bs.ctm.2020.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The importance of cell mechanics has long been recognized for the cell development and function. Biomechanics plays an important role in cell metabolism, regulation of mechanotransduction pathways and also modulation of nuclear response. The mechanical properties of the cell are likely determined by, among many others, the cytoskeleton elasticity, membrane tension and cell-substrate adhesion. This coordinated but complex mechanical interplay is required however, for the cell to respond to and influence in a reciprocal manner the chemical and mechanical signals from the extracellular matrix (ECM). In an effort to better and more fully understand the cell mechanics, the role of nuclear mechanics has emerged as an important contributor to the overall cellular mechanics. It is not too difficult to appreciate the physical connection between the nucleus and the cytoskeleton network that may be connected to the ECM through the cell membrane. Transmission of forces from ECM through this connection is essential for a wide range of cellular behaviors and functions such as cytoskeletal reorganization, nuclear movement, cell migration and differentiation. Unlike the cellular mechanics that can be measured using a number of biophysical techniques that were developed in the past few decades, it still remains a daunting challenge to probe the nuclear mechanics directly. In this paper, we therefore aim to provide informative description of the cell membrane and cytoskeleton mechanics, followed by unique computational modeling efforts to elucidate the nucleus-cytoskeleton coupling. Advances in our knowledge of complete cellular biomechanics and mechanotransduction may lead to clinical relevance and applications in mechano-diseases such as atherosclerosis, stem cell-based therapies, and the development of tissue engineered products.
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Affiliation(s)
- Caleb Liebman
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, United States
| | - Andrew McColloch
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, United States
| | - Manoochehr Rabiei
- Department of Mechanical and Aerospace Engineering, University of Texas at Arlington, Arlington, TX, United States
| | - Alan Bowling
- Department of Mechanical and Aerospace Engineering, University of Texas at Arlington, Arlington, TX, United States.
| | - Michael Cho
- Department of Bioengineering, University of Texas at Arlington, Arlington, TX, United States.
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4
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Haas M, Janiga M. Variation in erythrocyte morphology in alpine accentors (Prunella collaris Scop.) from Tian Shan, Rila and the High Tatra mountains and effects of molting. THE EUROPEAN ZOOLOGICAL JOURNAL 2020. [DOI: 10.1080/24750263.2020.1813821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Affiliation(s)
- M. Haas
- Institute of High Mountain Biology, University of Žilina, Tatranská Javorina, Slovakia
| | - M. Janiga
- Institute of High Mountain Biology, University of Žilina, Tatranská Javorina, Slovakia
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5
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Abstract
At the nuclear periphery, associations of chromatin with the nuclear lamina through lamina-associated domains (LADs) aid functional organization of the genome. We review the organization of LADs and provide evidence of LAD heterogeneity from cell ensemble and single-cell data. LADs are typically repressive environments in the genome; nonetheless, we discuss findings of lamin interactions with regulatory elements of active genes, and the role lamins may play in genome regulation. We address the relationship between LADs and other genome organizers, and the involvement of LADs in laminopathies. The current data lay the basis for future studies on the significance of lamin-chromatin interactions in health and disease.
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Affiliation(s)
- Nolwenn Briand
- Department of Molecular Medicine, Faculty of Medicine, University of Oslo, PO Box 1112 Blindern, 0317, Oslo, Norway
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424, Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Faculty of Medicine, University of Oslo, PO Box 1112 Blindern, 0317, Oslo, Norway.
- Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424, Oslo, Norway.
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6
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Song J, Meng X, Zhang H, Zhao K, Hu Y, Xie H. Probing Multidimensional Mechanical Phenotyping of Intracellular Structures by Viscoelastic Spectroscopy. ACS APPLIED MATERIALS & INTERFACES 2020; 12:1913-1923. [PMID: 31802656 DOI: 10.1021/acsami.9b19597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mechanical phenotyping of complex cellular structures gives insight into the process and function of mechanotransduction in biological systems. Several methods have been developed to characterize intracellular elastic moduli, while direct viscoelastic characterization of intracellular structures is still challenging. Here, we develop a needle tip viscoelastic spectroscopy method to probe multidimensional mechanical phenotyping of intracellular structures during a mini-invasive penetrating process. Viscoelastic spectroscopy is determined by magnetically driven resonant vibration (about 15 kHz) with a tiny amplitude. It not only detects the unique dynamic stiffness, damping, and loss tangent of the cell membrane-cytoskeleton and nucleus-nuclear lamina but also bridges viscoelastic parameters between the mitotic phase and interphase. Self-defined dynamic mechanical ratios of these two phases can identify two malignant cervical cancer cell lines (HeLa-HPV18+, SiHa-HPV16+) whose membrane or nucleus elastic moduli are indistinguishable. This technique provides a quantitative method for studying mechanosensation, mechanotransduction, and mechanoresponse of intracellular structures from a dynamic mechanical perspective. This technique has the potential to become a reliable quantitative measurement method for dynamic mechanical studies of intracellular structures.
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7
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Sneider A, Hah J, Wirtz D, Kim DH. Recapitulation of molecular regulators of nuclear motion during cell migration. Cell Adh Migr 2019; 13:50-62. [PMID: 30261154 PMCID: PMC6527386 DOI: 10.1080/19336918.2018.1506654] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/05/2018] [Accepted: 07/18/2018] [Indexed: 01/12/2023] Open
Abstract
Cell migration is a highly orchestrated cellular event that involves physical interactions of diverse subcellular components. The nucleus as the largest and stiffest organelle in the cell not only maintains genetic functionality, but also actively changes its morphology and translocates through dynamic formation of nucleus-bound contractile stress fibers. Nuclear motion is an active and essential process for successful cell migration and nucleus self-repairs in response to compression and extension forces in complex cell microenvironment. This review recapitulates molecular regulators that are crucial for nuclear motility during cell migration and highlights recent advances in nuclear deformation-mediated rupture and repair processes in a migrating cell.
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Affiliation(s)
- Alexandra Sneider
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Jungwon Hah
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
| | - Denis Wirtz
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Dong-Hwee Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea
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8
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Lambert MW. The functional importance of lamins, actin, myosin, spectrin and the LINC complex in DNA repair. Exp Biol Med (Maywood) 2019; 244:1382-1406. [PMID: 31581813 PMCID: PMC6880146 DOI: 10.1177/1535370219876651] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Three major proteins in the nucleoskeleton, lamins, actin, and spectrin, play essential roles in maintenance of nuclear architecture and the integrity of the nuclear envelope, in mechanotransduction and mechanical coupling between the nucleoskeleton and cytoskeleton, and in nuclear functions such as regulation of gene expression, transcription and DNA replication. Less well known, but critically important, are the role these proteins play in DNA repair. The A-type and B-type lamins, nuclear actin and myosin, spectrin and the LINC (linker of nucleoskeleton and cytoskeleton) complex each function in repair of DNA damage utilizing various repair pathways. The lamins play a role in repair of DNA double-strand breaks (DSBs) by nonhomologous end joining (NHEJ) or homologous recombination (HR). Actin is involved in repair of DNA DSBs and interacts with myosin in facilitating relocalization of these DSBs in heterochromatin for HR repair. Nonerythroid alpha spectrin (αSpII) plays a critical role in repair of DNA interstrand cross-links (ICLs) where it acts as a scaffold in recruitment of repair proteins to sites of damage and is important in the initial damage recognition and incision steps of the repair process. The LINC complex contributes to the repair of DNA DSBs and ICLs. This review will address the important functions of these proteins in the DNA repair process, their mechanism of action, and the profound impact a defect or deficiency in these proteins has on cellular function. The critical roles of these proteins in DNA repair will be further emphasized by discussing the human disorders and the pathophysiological changes that result from or are related to deficiencies in these proteins. The demonstrated function for each of these proteins in the DNA repair process clearly indicates that there is another level of complexity that must be considered when mechanistically examining factors crucial for DNA repair.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology, Immunology and Laboratory
Medicine, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
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9
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Suspension State Promotes Drug Resistance of Breast Tumor Cells by Inducing ABCC3 Overexpression. Appl Biochem Biotechnol 2019; 190:410-422. [PMID: 31367898 DOI: 10.1007/s12010-019-03084-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/05/2019] [Indexed: 12/19/2022]
Abstract
Mechanical microenvironment plays a critical role in cancer drug resistance and this study supposed that suspension state might be involved in drug resistance of breast tumor cells. The viability of cell was detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Cell cycle and apoptosis were detected by flow cytometry. Gene and protein were tested by RT-qPCR and Western blot, respectively. Drug resistance of MDA-MB-231 cells cultured for 72 h under suspension state was significantly increased. Suspension state was found to induce the overexpression of adenosine triphosphate-binding cassette subfamily C member 3 (ABCC3) in MDA-MB-231 cells. Silencing of ABCC3 significantly decreased drug resistance of suspension MDA-MB-231 cells. Moreover, suspension state was able to increase lamin A/C accumulation in MDA-MB-231 cells and lamin A/C regulated the expression of ABCC3. Moreover, lamin A/C knockdown also decreased drug resistance of suspension MDA-MB-231 cells, but the effect on drug resistance was less than that of ABCC3 knockdown. Suspension state plays a vital role in promoting drug resistance of MDA-MB-231 cells by inducing ABCC3 overexpression, and lamin A/C accumulation is associated with this process.
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10
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Östlund C, Chang W, Gundersen GG, Worman HJ. Pathogenic mutations in genes encoding nuclear envelope proteins and defective nucleocytoplasmic connections. Exp Biol Med (Maywood) 2019; 244:1333-1344. [PMID: 31299860 DOI: 10.1177/1535370219862243] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mutations in genes encoding nuclear lamins and associated nuclear envelope proteins have been linked to a broad range of inherited diseases affecting different tissues and organs. These diseases are often referred to as laminopathies. Scientists have yet to elucidate exactly how pathogenic mutations leading to alteration of a nuclear envelope protein cause disease. Our relatively recent research has shown that pathogenic mutations in genes encoding nuclear envelope proteins lead to defective nucleocytoplasmic connections that disrupt proper functioning of the linker of nucleoskeleton and cytoskeleton complex in the establishment of cell polarity. These defects may explain, at least in part, pathogenic mechanisms underlying laminopathies.Impact statementMutations in genes encoding nuclear lamins and associated nuclear envelope proteins have been linked to several diseases affecting different tissues and organs. The pathogenic mechanisms underlying these diseases, often called laminopathies, remain poorly understood. Increased knowledge of the functions of different nuclear envelope proteins and the interactions between them is crucial to elucidate these disease mechanisms. Our research has shown that pathogenic mutations in genes encoding nuclear envelope proteins lead to defective nucleocytoplasmic connections that disrupt proper functioning of the linker of nucleoskeleton and cytoskeleton (LINC) complex in the establishment of cell polarity. These defects may contribute to the pathogenesis of laminopathies and provide novel targets for therapeutics.
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Affiliation(s)
- Cecilia Östlund
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.,Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Wakam Chang
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Howard J Worman
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.,Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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11
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Jevtić P, Milunović-Jevtić A, Dilsaver MR, Gatlin JC, Levy DL. Use of Xenopus cell-free extracts to study size regulation of subcellular structures. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2018; 60:277-288. [PMID: 27759156 DOI: 10.1387/ijdb.160158dl] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Striking size variations are prominent throughout biology, at the organismal, cellular, and subcellular levels. Important fundamental questions concern organelle size regulation and how organelle size is regulated relative to cell size, also known as scaling. Uncovering mechanisms of organelle size regulation will inform the functional significance of size as well as the implications of misregulated size, for instance in the case of nuclear enlargement in cancer. Xenopus egg and embryo extracts are powerful cell-free systems that have been utilized extensively for mechanistic and functional studies of various organelles and subcellular structures. The open biochemical nature of the extract permits facile manipulation of its composition, and in recent years extract approaches have illuminated mechanisms of organelle size regulation. This review largely focuses on in vitro Xenopus studies that have identified regulators of nuclear and spindle size. We also discuss potential relationships between size scaling of the nucleus and spindle, size regulation of other subcellular structures, and extract experiments that have clarified developmental timing mechanisms. We conclude by offering some future prospects, notably the integration of Xenopus extract with microfluidic technology.
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Affiliation(s)
- Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, Laramie, WY, USA
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12
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Turgay Y, Medalia O. The structure of lamin filaments in somatic cells as revealed by cryo-electron tomography. Nucleus 2017. [PMID: 28635493 DOI: 10.1080/19491034.2017.1337622] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Metazoan nuclei are equipped with nuclear lamina - a thin layer of intermediate filaments (IFs) mostly built of nuclear lamins facing the inner nuclear membrane (INM). The nuclear lamina serves as an interaction hub for INM-proteins, soluble nuclear factors and DNA. It confers structural and mechanical stability to the nucleus, transduces mechanical forces and biochemical signals across the nuclear envelope (NE) and regulates the organization of chromatin. By using cryo-electron tomography (cryo-ET), we recently provided an unprecedented view into the 3D organization of lamin filaments within the lamina meshwork in mammalian somatic cells. Through implementation of averaging procedures, we resolved the rod and globular Ig-fold domains of lamin filaments. The density maps suggested that they assemble into 3.5 nm thick filaments. Our analysis revealed interesting structural differences between nucleoplasmic and cytoplasmic intermediate filaments, raising the question of which molecular cues define their assembly modes inside the cell.
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Affiliation(s)
- Y Turgay
- a Department of Biochemistry , University of Zurich , Zurich , Switzerland
| | - O Medalia
- a Department of Biochemistry , University of Zurich , Zurich , Switzerland.,b Department of Life Sciences and the National Institute for Biotechnology in the Negev , Ben-Gurion University , Beer-Sheva , Israel
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13
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Skinner BM, Johnson EEP. Nuclear morphologies: their diversity and functional relevance. Chromosoma 2017; 126:195-212. [PMID: 27631793 PMCID: PMC5371643 DOI: 10.1007/s00412-016-0614-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 08/17/2016] [Indexed: 12/20/2022]
Abstract
Studies of chromosome and genome biology often focus on condensed chromatin in the form of chromosomes and neglect the non-dividing cells. Even when interphase nuclei are considered, they are often then treated as interchangeable round objects. However, different cell types can have very different nuclear shapes, and these shapes have impacts on cellular function; indeed, many pathologies are linked with alterations to nuclear shape. In this review, we describe some of the nuclear morphologies beyond the spherical and ovoid. Many of the leukocytes of the immune system have lobed nuclei, which aid their flexibility and migration; smooth muscle cells have a spindle shaped nucleus, which must deform during muscle contractions; spermatozoa have highly condensed nuclei which adopt varied shapes, potentially associated with swimming efficiency. Nuclei are not passive passengers within the cell. There are clear effects of nuclear shape on the transcriptional activity of the cell. Recent work has shown that regulation of gene expression can be influenced by nuclear morphology, and that cells can drastically remodel their chromatin during differentiation. The link between the nucleoskeleton and the cytoskeleton at the nuclear envelope provides a mechanism for transmission of mechanical forces into the nucleus, directly affecting chromatin compaction and organisation.
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Affiliation(s)
- Benjamin M Skinner
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
| | - Emma E P Johnson
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
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14
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Turgay Y, Eibauer M, Goldman AE, Shimi T, Khayat M, Ben-Harush K, Dubrovsky-Gaupp A, Sapra KT, Goldman RD, Medalia O. The molecular architecture of lamins in somatic cells. Nature 2017; 543:261-264. [PMID: 28241138 DOI: 10.1038/nature21382] [Citation(s) in RCA: 274] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 01/11/2017] [Indexed: 01/13/2023]
Abstract
The nuclear lamina is a fundamental constituent of metazoan nuclei. It is composed mainly of lamins, which are intermediate filament proteins that assemble into a filamentous meshwork, bridging the nuclear envelope and chromatin. Besides providing structural stability to the nucleus, the lamina is involved in many nuclear activities, including chromatin organization, transcription and replication. However, the structural organization of the nuclear lamina is poorly understood. Here we use cryo-electron tomography to obtain a detailed view of the organization of the lamin meshwork within the lamina. Data analysis of individual lamin filaments resolves a globular-decorated fibre appearance and shows that A- and B-type lamins assemble into tetrameric filaments of 3.5 nm thickness. Thus, lamins exhibit a structure that is remarkably different from the other canonical cytoskeletal elements. Our findings define the architecture of the nuclear lamin meshworks at molecular resolution, providing insights into their role in scaffolding the nuclear lamina.
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Affiliation(s)
- Yagmur Turgay
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Matthias Eibauer
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Anne E Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, Illinois 60611, USA
| | - Takeshi Shimi
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, Illinois 60611, USA
| | - Maayan Khayat
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, 84105 Beer-Sheva, Israel
| | - Kfir Ben-Harush
- Department of Chemical Engineering, Shamoon College of Engineering, Jabotinsky 84, 77245 Ashdod, Israel
| | - Anna Dubrovsky-Gaupp
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - K Tanuj Sapra
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, 303 E Chicago Avenue, Chicago, Illinois 60611, USA
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.,Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, 84105 Beer-Sheva, Israel
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15
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Hwang SS, Kim LK, Lee GR, Flavell RA. Role of OCT-1 and partner proteins in T cell differentiation. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1859:825-31. [PMID: 27126747 DOI: 10.1016/j.bbagrm.2016.04.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 12/24/2022]
Abstract
The understanding of CD4 T cell differentiation gives important insights into the control of immune responses against various pathogens and in autoimmune diseases. Naïve CD4 T cells become effector T cells in response to antigen stimulation in combination with various environmental cytokine stimuli. Several transcription factors and cis-regulatory regions have been identified to regulate epigenetic processes on chromatin, to allow the production of proper effector cytokines during CD4 T cell differentiation. OCT-1 (Pou2f1) is well known as a widely expressed transcription factor in most tissues and cells. Although the importance of OCT-1 has been emphasized during development and differentiation, its detailed molecular underpinning and precise role are poorly understood. Recently, a series of studies have reported that OCT-1 plays a critical role in CD4 T cells through regulating gene expression during differentiation and mediating long-range chromosomal interactions. In this review, we will describe the role of OCT-1 in CD4 T cell differentiation and discuss how this factor orchestrates the fate and function of CD4 effector T cells.
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Affiliation(s)
- Soo Seok Hwang
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Lark Kyun Kim
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA; Severance Biomedical Science Institute, Gangnam Severance Hospital, Yonsei University College of Medicine, 211 Eonjuro, Gangnam-gu, Seoul 135-720, South Korea
| | - Gap Ryol Lee
- Department of Life-Science, Sogang University, Baekbeom-ro, Seoul 121-742, South Korea
| | - Richard A Flavell
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA; Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520, USA.
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16
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Abstract
It is now well accepted that defined architectural compartments within the cell nucleus can regulate the transcriptional activity of chromosomal domains within their vicinity. However, it is generally unclear how these compartments are formed. The nuclear periphery has received a great deal of attention as a repressive compartment that is implicated in many cellular functions during development and disease. The inner nuclear membrane, the nuclear lamina, and associated proteins compose the nuclear periphery and together they interact with proximal chromatin creating a repressive environment. A new study by Harr et al. identifies specific protein-DNA interactions and epigenetic states necessary to re-position chromatin to the nuclear periphery in a cell-type specific manner. Here, we review concepts in gene positioning within the nucleus and current accepted models of dynamic gene repositioning within the nucleus during differentiation. This study highlights that myriad pathways lead to nuclear organization.
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Affiliation(s)
- Molly R Gordon
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Benjamin D Pope
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Jiao Sima
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.,Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, FL, USA
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17
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Shen J, Chen W, Shao B, Qi Y, Xia Z, Wang F, Wang L, Guo X, Huang X, Sha J. Lamin A/C proteins in the spermatid acroplaxome are essential in mouse spermiogenesis. Reproduction 2014; 148:479-87. [DOI: 10.1530/rep-14-0012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Spermiogenesis is a complex process of terminal differentiation that is necessary to produce mature sperm. Using protein expression profiles of mouse and human testes generated from our previous studies, we chose to examine the actions of lamin A/C in the current investigation. Lamin A and lamin C are isoforms of the A-type lamins that are encoded by theLMNAgene. Our results showed that lamin A/C was expressed in the mouse testis throughout the different stages of spermatogenesis and in mature sperm. Lamin A/C was also expressed in mouse haploid germ cells and was found to be localized to the acroplaxome in spermiogenesis, from round spermatids until mature spermatozoa. The decreased expression of lamin A/C following injections of siRNA againstLmnacaused a significant increase in caudal sperm head abnormalities when compared with negative controls. These abnormalities were characterized by increased fragmentation of the acrosome and abnormal vesicles, which failed to fuse to the developing acrosome. This fragmentation also caused significant alterations in nuclear elongation and acrosome formation. Furthermore, we found that lamin A/C interacted with the microtubule plus-end-tracking protein CLIP170. These results suggest that lamin A/C is critical for proper structural and functional development of the sperm acrosome and head shape.
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Liu H, Wen J, Xiao Y, Liu J, Hopyan S, Radisic M, Simmons CA, Sun Y. In situ mechanical characterization of the cell nucleus by atomic force microscopy. ACS NANO 2014; 8:3821-8. [PMID: 24673613 DOI: 10.1021/nn500553z] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The study of nuclear mechanical properties can provide insights into nuclear dynamics and its role in cellular mechanotransduction. While several methods have been developed to characterize nuclear mechanical properties, direct intracellular probing of the nucleus in situ is challenging. Here, a modified AFM (atomic force microscopy) needle penetration technique is demonstrated to mechanically characterize cell nuclei in situ. Cytoplasmic and nuclear stiffness were determined based on two different segments on the AFM indentation curves and were correlated with simultaneous confocal Z-stack microscopy reconstructions. On the basis of direct intracellular measurement, we show that the isolated nuclei from fibroblast-like cells exhibited significantly lower Young's moduli than intact nuclei in situ. We also show that there is in situ nucleus softening in the highly metastatic bladder cancer cell line T24 when compared to its less metastatic counterpart RT4. This technique has potential to become a reliable quantitative measurement tool for intracellular mechanics studies.
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Affiliation(s)
- Haijiao Liu
- Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, Ontario, Canada M5S 3G8
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Jevtić P, Levy DL. Mechanisms of nuclear size regulation in model systems and cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:537-69. [PMID: 24563365 DOI: 10.1007/978-1-4899-8032-8_25] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Changes in nuclear size have long been used by cytopathologists as an important parameter to diagnose, stage, and prognose many cancers. Mechanisms underlying these changes and functional links between nuclear size and malignancy are largely unknown. Understanding mechanisms of nuclear size regulation and the physiological significance of proper nuclear size control will inform the interplay between altered nuclear size and oncogenesis. In this chapter we review what is known about molecular mechanisms of nuclear size control based on research in model experimental systems including yeast, Xenopus, Tetrahymena, Drosophila, plants, mice, and mammalian cell culture. We discuss how nuclear size is influenced by DNA ploidy, nuclear structural components, cytoplasmic factors and nucleocytoplasmic transport, the cytoskeleton, and the extracellular matrix. Based on these mechanistic insights, we speculate about how nuclear size might impact cell physiology and whether altered nuclear size could contribute to cancer development and progression. We end with some outstanding questions about mechanisms and functions of nuclear size regulation.
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Affiliation(s)
- Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, 1000 E. University Avenue, Laramie, WY, 82071, USA,
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Li Z, Zhu Y, Zhai Y, R Castroagudin M, Bao Y, White TE, Glavy JS. Werner complex deficiency in cells disrupts the Nuclear Pore Complex and the distribution of lamin B1. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1833:3338-3345. [PMID: 24050918 DOI: 10.1016/j.bbamcr.2013.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 07/22/2013] [Accepted: 09/03/2013] [Indexed: 11/24/2022]
Abstract
From the surrounding shell to the inner machinery, nuclear proteins provide the functional plasticity of the nucleus. This study highlights the nuclear association of Pore membrane (POM) protein NDC1 and Werner protein (WRN), a RecQ helicase responsible for the DNA instability progeria disorder, Werner Syndrome. In our previous publication, we connected the DNA damage sensor Werner's Helicase Interacting Protein (WHIP), a binding partner of WRN, to the NPC. Here, we confirm the association of the WRN/WHIP complex and NDC1. In established WRN/WHIP knockout cell lines, we further demonstrate the interdependence of WRN/WHIP and Nucleoporins (Nups). These changes do not completely abrogate the barrier of the Nuclear Envelope (NE) but do affect the distribution of FG Nups and the RAN gradient, which are necessary for nuclear transport. Evidence from WRN/WHIP knockout cell lines demonstrates changes in the processing and nucleolar localization of lamin B1. The appearance of "RAN holes" void of RAN corresponds to regions within the nucleolus filled with condensed pools of lamin B1. From WRN/WHIP knockout cell line extracts, we found three forms of lamin B1 that correspond to mature holoprotein and two potential post-translationally modified forms of the protein. Upon treatment with topoisomerase inhibitors lamin B1 cleavage occurs only in WRN/WHIP knockout cells. Our data suggest the link of the NDC1 and WRN as one facet of the network between the nuclear periphery and genome stability. Loss of WRN complex leads to multiple alterations at the NPC and the nucleolus.
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Affiliation(s)
- Zhi Li
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Yizhou Zhu
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Yujia Zhai
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Michelle R Castroagudin
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Yifei Bao
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Tommy E White
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA
| | - Joseph S Glavy
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
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Lamin misexpression upregulates three distinct ubiquitin ligase systems that degrade ATR kinase in HeLa cells. Mol Cell Biochem 2012; 365:323-32. [PMID: 22382637 DOI: 10.1007/s11010-012-1272-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 02/16/2012] [Indexed: 12/27/2022]
Abstract
Lamins are the major structural components of the nucleus and mutations in the human lamin A gene cause a number of genetic diseases collectively termed laminopathies. At the cellular level, lamin A mutations cause aberrant nuclear morphology and defects in nuclear functions such as the response to DNA damage. We have investigated the mechanism of depletion of a key damage sensor, ATR (Ataxia-telangiectasia-mutated-and-Rad3-related) kinase, in HeLa cells expressing lamin A mutants or lamin A shRNA. The degradation of ATR kinase in these cells was through the proteasomal pathway as it was reversed by the proteasomal inhibitor MG132. Expression of lamin A mutants or shRNA led to transcriptional activation of three ubiquitin ligase components, namely, RNF123 (ring finger protein 123), HECW2 (HECT domain ligase W2) and the F-box protein FBXW10. Ectopic expression of RNF123, HECW2 or FBXW10 directly resulted in proteasomal degradation of ATR kinase and the ring domain of RNF123 was required for this degradation. However, these ligases did not alter the stability of DNA-dependent protein kinase, which is not depleted upon lamin misexpression. Although degradation of ATR kinase was reversed by MG132, it was not affected by the nuclear export inhibitor, leptomycin B, suggesting that ATR kinase is degraded within the nucleus. Our findings indicate that lamin misexpression can lead to deleterious effects on the stability of the key DNA damage sensor, ATR kinase by upregulation of specific components of the ubiquitination pathway.
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Structures of the lamin A/C R335W and E347K mutants: Implications for dilated cardiolaminopathies. Biochem Biophys Res Commun 2012; 418:217-21. [DOI: 10.1016/j.bbrc.2011.12.136] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 12/25/2011] [Indexed: 11/19/2022]
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Abstract
This chapter focuses on the three-dimensional organization of the nucleus in normal, early genomically unstable, and tumor cells. A cause-consequence relationship is discussed between nuclear alterations and the resulting genomic rearrangements. Examples are presented from studies on conditional Myc deregulation, experimental tumorigenesis in mouse plasmacytoma, nuclear remodeling in Hodgkin's lymphoma, and in adult glioblastoma. A model of nuclear remodeling is proposed for cancer progression in multiple myeloma. Current models of nuclear remodeling are described, including our model of altered nuclear architecture and the onset of genomic instability.
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Abstract
In metazoan cells, the heterochromatin is generally localized at the nuclear periphery, whereas active genes are preferentially found in the nuclear interior. In the present paper, we review current evidence showing that components of the nuclear lamina interact directly with heterochromatin, which implicates the nuclear lamina in a mechanism of specific gene retention at the nuclear periphery and release to the nuclear interior upon gene activation. We also discuss recent data showing that mutations in lamin proteins affect gene positioning and expression, providing a potential mechanism for how these mutations lead to tissue-specific diseases.
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Lamins, laminopathies and disease mechanisms: Possible role for proteasomal degradation of key regulatory proteins. J Biosci 2011; 36:471-9. [DOI: 10.1007/s12038-011-9085-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Meyer AJ, Almendrala DK, Go MM, Krauss SW. Structural protein 4.1R is integrally involved in nuclear envelope protein localization, centrosome-nucleus association and transcriptional signaling. J Cell Sci 2011; 124:1433-44. [PMID: 21486941 DOI: 10.1242/jcs.077883] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The multifunctional structural protein 4.1R is required for assembly and maintenance of functional nuclei but its nuclear roles are unidentified. 4.1R localizes within nuclei, at the nuclear envelope, and in cytoplasm. Here we show that 4.1R, the nuclear envelope protein emerin and the intermediate filament protein lamin A/C co-immunoprecipitate, and that 4.1R-specific depletion in human cells by RNA interference produces nuclear dysmorphology and selective mislocalization of proteins from several nuclear subcompartments. Such 4.1R-deficiency causes emerin to partially redistribute into the cytoplasm, whereas lamin A/C is disorganized at nuclear rims and displaced from nucleoplasmic foci. The nuclear envelope protein MAN1, nuclear pore proteins Tpr and Nup62, and nucleoplasmic proteins NuMA and LAP2α also have aberrant distributions, but lamin B and LAP2β have normal localizations. 4.1R-deficient mouse embryonic fibroblasts show a similar phenotype. We determined the functional effects of 4.1R-deficiency that reflect disruption of the association of 4.1R with emerin and A-type lamin: increased nucleus-centrosome distances, increased β-catenin signaling, and relocalization of β-catenin from the plasma membrane to the nucleus. Furthermore, emerin- and lamin-A/C-null cells have decreased nuclear 4.1R. Our data provide evidence that 4.1R has important functional interactions with emerin and A-type lamin that impact upon nuclear architecture, centrosome-nuclear envelope association and the regulation of β-catenin transcriptional co-activator activity that is dependent on β-catenin nuclear export.
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Affiliation(s)
- Adam J Meyer
- Department of Genome Dynamics, University of California, Berkeley, CA 94720, USA
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27
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Nesprins LINC the nucleus and cytoskeleton. Curr Opin Cell Biol 2010; 23:47-54. [PMID: 21177090 DOI: 10.1016/j.ceb.2010.11.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 11/19/2010] [Accepted: 11/27/2010] [Indexed: 01/08/2023]
Abstract
Like other spectrin repeat proteins, nesprins co-ordinate and maintain cellular architecture by linking membranous organelles to the cytoskeleton. However nuclear envelope (NE) nesprins, uniquely hardwire the nuclear lamina to the cytoskeleton and molecular motors. Emerging evidence suggests that nesprins also form a continuous network linking the plasma membrane to the NE that potentially translates mechanical stimuli into nuclear reorganisation. Surprisingly, this network is also essential for cytoskeletal organisation and its disruption has dramatic effects on nuclear migration, centrosomal positioning, focal adhesion maturation and cell motility. Herein we review recent advances in our understanding of how nesprins couple to various filamentous systems within the cell and emphasise the importance of both KASH and KASH-less nesprin isoforms in these interactions.
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28
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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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29
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Leach NR, Roller RJ. Significance of host cell kinases in herpes simplex virus type 1 egress and lamin-associated protein disassembly from the nuclear lamina. Virology 2010; 406:127-37. [PMID: 20674954 DOI: 10.1016/j.virol.2010.07.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 06/23/2010] [Accepted: 07/01/2010] [Indexed: 12/25/2022]
Abstract
The nuclear lamina is thought to be a steric barrier to the herpesvirus capsid. Disruption of the lamina accompanied by phosphorylation of lamina proteins is a conserved feature of herpesvirus infection. In HSV-1-infected cells, protein kinase C (PKC) alpha and delta isoforms are recruited to the nuclear membrane and PKC delta has been implicated in phosphorylation of emerin and lamin B. We tested two critical hypotheses about the mechanism and significance of lamina disruption. First, we show that chemical inhibition of all PKC isoforms reduced viral growth five-fold and inhibited capsid egress from the nucleus. However, specific inhibition of either conventional PKCs or PKC delta does not inhibit viral growth. Second, we show hyperphosphorylation of emerin by viral and cellular kinases is required for its disassociation from the lamina. These data support hypothesis that phosphorylation of lamina components mediates lamina disruption during HSV nuclear egress.
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Affiliation(s)
- Natalie R Leach
- Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA 52242, USA
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Nadeau M, Noël S, Laberge PY, Hurtubise J, Tchernof A. Adipose tissue lamin A/C messenger RNA expression in women. Metabolism 2010; 59:1106-14. [PMID: 20045150 DOI: 10.1016/j.metabol.2009.09.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 09/09/2009] [Indexed: 01/10/2023]
Abstract
Mutations in the lamin A/C gene (LMNA) cause lipodystrophy. However, little data are available on lamin A/C expression in various fat depots in women. We recruited 34 women scheduled for gynecologic surgery. Blood samples were collected on the morning of surgery to obtain a detailed lipid profile. Radiological examinations were performed to measure total body fat mass and abdominal fat accumulation. Fat samples were taken from the subcutaneous (SC) fat depot and from the greater omentum (OM) during the surgical procedure. Whole adipose tissue samples were used for total messenger RNA (mRNA) extraction and real-time polymerase chain reaction quantification of the LMNA transcript. No association was observed between lamin A/C mRNA expression, either in SC or OM fat tissue, and adiposity measures. Women with low SC lamin A/C expression, identified on the basis of the median value of SC lamin A/C mRNA expression, had a significantly altered lipid profile including lower levels of high-density lipoprotein (HDL) cholesterol and HDL(2) cholesterol and reduced HDL(2) cholesterol to HDL(3) cholesterol ratio (P < .05 for all). These women were also characterized by higher cholesterol to HDL cholesterol, low-density lipoprotein-triglycerides, very low-density lipoprotein-apolipoprotein B, and low-density lipoprotein cholesterol to HDL cholesterol (P < .05 for all). Low SC lamin A/C mRNA expression levels were also associated with significantly increased lipolysis in isolated fat cells from this fat depot. Specifically, the response to lipolytic agent isoproterenol was significantly increased at doses ranging from 10(-5) to 10(-10) mol/L (P < .05). A similar trend was observed in OM fat cells but did not reach significance. In conclusion, low lamin A/C expression in SC adipose tissue is associated with significant alterations in the lipid profile and increased fat cell lipolysis, independent of the level of total or abdominal adiposity.
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Affiliation(s)
- Mélanie Nadeau
- Molecular Endocrinology and Genomics Center, Laval University Medical Research Center, Quebec City, Quebec, Canada G1V 4G2
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Trypanosoma cruzi: identification of DNA targets of the nuclear periphery coiled-coil protein TcNUP-1. Exp Parasitol 2010; 127:147-52. [PMID: 20647012 DOI: 10.1016/j.exppara.2010.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 07/12/2010] [Accepted: 07/15/2010] [Indexed: 11/23/2022]
Abstract
The nuclear lamina is a structure that lines the inner nuclear membrane. In metazoans, lamins are the primary structural components of the nuclear lamina and are involved in several processes. Eukaryotes that lack lamins have distinct proteins with homologous functions. Some years ago, a coiled-coil protein in Trypanosoma brucei, NUP-1, was identified as the major filamentous component of its nuclear lamina. However, its precise role has not been determined. We characterized a homologous protein in Trypanosoma cruzi, TcNUP-1, and identified its in vivo DNA binding sites using a chromatin immunoprecipitation assay. We demonstrate for the first time that TcNUP-1 associates with chromosomal regions containing large non-tandem arrays of genes encoding surface proteins. We therefore suggest that TcNUP-1 is a structural protein that plays an essential role in nuclear organization by anchoring T. cruzi chromosomes to the nuclear envelope.
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Clayton P, Fischer B, Mann A, Mansour S, Rossier E, Veen M, Lang C, Baasanjav S, Kieslich M, Brossuleit K, Gravemann S, Schnipper N, Karbasyian M, Demuth I, Zwerger M, Vaya A, Utermann G, Mundlos S, Stricker S, Sperling K, Hoffmann K. Mutations causing Greenberg dysplasia but not Pelger anomaly uncouple enzymatic from structural functions of a nuclear membrane protein. Nucleus 2010; 1:354-66. [PMID: 21327084 PMCID: PMC3027044 DOI: 10.4161/nucl.1.4.12435] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 05/21/2010] [Accepted: 05/21/2010] [Indexed: 01/31/2023] Open
Abstract
The lamin B receptor (LBR) is an inner nuclear membrane protein with a structural function interacting with chromatin and lamins, and an enzymatic function as a sterol reductase. Heterozygous LBR mutations cause nuclear hyposegmentation in neutrophils (Pelger anomaly), while homozygous mutations cause prenatal death with skeletal defects and abnormal sterol metabolism (Greenberg dysplasia). It has remained unclear whether the lethality in Greenberg dysplasia is due to cholesterol defects or altered nuclear morphology.To answer this question we characterized two LBR missense mutations and showed that they cause Greenberg dysplasia. Both mutations affect residues that are evolutionary conserved among sterol reductases. In contrast to wildtype LBR, both mutations failed to rescue C14 sterol reductase deficient yeast, indicating an enzymatic defect. We found no Pelger anomaly in the carrier parent excluding marked effects on nuclear structure. We studied Lbr in mouse embryos and demonstrate expression in skin and the developing skeletal system consistent with sites of histological changes in Greenberg dysplasia. Unexpectedly we found in disease-relevant cell types not only nuclear but also cytoplasmatic LBR localization. The cytoplasmatic LBR staining co-localized with ER-markers and is thus consistent with the sites of endogeneous sterol synthesis. We conclude that LBR missense mutations can abolish sterol reductase activity, causing lethal Greenberg dysplasia but not Pelger anomaly. The findings separate the metabolic from the structural function and indicate that the sterol reductase activity is essential for human intrauterine development.
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Affiliation(s)
- Peter Clayton
- UCL Institute of Child Health with Great Ormond Street Hospital for ChildrenNHS Trust; London, UK
| | - Björn Fischer
- Institute for Medical Genetics; Charité University Medicine; Berlin, Germany
| | - Anuska Mann
- UCL Institute of Child Health with Great Ormond Street Hospital for ChildrenNHS Trust; London, UK
| | - Sahar Mansour
- SW Thames Regional Genetics Service; St. George's Hospital Medical School; University of London; London, UK
| | - Eva Rossier
- Humangenetik; Universitätsklinikum Tuebingen; Tuebingen, Germany
| | | | | | - Sevjidmaa Baasanjav
- Division of Nephrology; Department of Medicine, Neurology and Dermatology; University Hospital Leipzig; Leipzig, Germany
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Moritz Kieslich
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Katja Brossuleit
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Sophia Gravemann
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Nele Schnipper
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Mohsen Karbasyian
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Ilja Demuth
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Monika Zwerger
- B065 Functional Architecture of the Cell; German Cancer Research Center (DKFZ); Heidelberg, Germany
| | - Amparo Vaya
- Department of Clinical Pathology; La Fe University Hospital; Valencia, Spain
| | - Gerd Utermann
- Human Genetics; Department of Medical Genetics, Molecular and Clinical Pharmacology; Innsbruck, Austria
| | - Stefan Mundlos
- Institute for Medical Genetics; Charité University Medicine; Berlin, Germany
- Max Planck Institute for Molecular Genetics; Berlin, Germany
| | - Sigmar Stricker
- Max Planck Institute for Molecular Genetics; Berlin, Germany
| | - Karl Sperling
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
| | - Katrin Hoffmann
- Institute for Medical Genetics; Charité University Medicine; Berlin, Germany
- Institute for Human Genetics; Charité University Medicine; Berlin, Germany
- Max Planck Institute for Human Development; Berlin, Germany
- The Berlin Aging Study II; Research Group on Geriatrics; Charité University Medicine; Berlin, Germany
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Martin C, Chen S, Jackson DA. Inheriting nuclear organization: can nuclear lamins impart spatial memory during post-mitotic nuclear assembly? Chromosome Res 2010; 18:525-41. [PMID: 20568006 DOI: 10.1007/s10577-010-9137-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 05/27/2010] [Accepted: 05/27/2010] [Indexed: 11/28/2022]
Abstract
Cell type and tissue architecture correlate with genome organization in higher eukaryotes, and structural nuclear landmarks are faithfully transmitted from one cell generation to the next. However, how nuclear components find their place in the nucleus after mitosis is still a matter of debate. As the major structural proteins within nuclei, the nuclear lamins are good candidates to re-establish nuclear compartments following mitosis. Human cells with reduced expression of the major B-type lamin protein, lamin B1, were generated using RNA interference. Mitotic and nuclear assembly phenotypes were then visualized in both fixed and living cells. Mitotic defects in lamin B1-depleted cells correlated with a general deterioration in nuclear compartmentalization and chromatin structure, frequent failure of chromosome segregation, and profound disorganization of centromeres. Examination of cells with normal lamin B1 expression indicated that small lamin B1 foci remain associated with major nuclear compartments--chromatin, nucleoli, and nuclear speckles--during an unperturbed mitosis. Our experiments show that normal lamin B1 expression is required for successful cell division and provide preliminary evidence that lamin B1-containing remnants of the interphase nucleoskeleton persist throughout mitosis. We suggest that these residual structures provide landmarks that are targeted during nuclear reassembly to allow key features of nuclear organization to be inherited from one cell cycle to the next.
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Affiliation(s)
- Catherine Martin
- Faculty of Life Sciences, University of Manchester, MIB, 131 Princess Street, Manchester, M1 7DN, UK
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Chaturvedi P, Parnaik VK. Lamin A rod domain mutants target heterochromatin protein 1alpha and beta for proteasomal degradation by activation of F-box protein, FBXW10. PLoS One 2010; 5:e10620. [PMID: 20498703 PMCID: PMC2869352 DOI: 10.1371/journal.pone.0010620] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 04/20/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lamins are major structural proteins of the nucleus and contribute to the organization of various nuclear functions. Mutations in the human lamin A gene cause a number of highly degenerative diseases, collectively termed as laminopathies. Cells expressing lamin mutations exhibit abnormal nuclear morphology and altered heterochromatin organization; however, the mechanisms responsible for these defects are not well understood. METHODOLOGY AND PRINCIPAL FINDINGS The lamin A rod domain mutants G232E, Q294P and R386K are either diffusely distributed or form large aggregates in the nucleoplasm, resulting in aberrant nuclear morphology in various cell types. We examined the effects of these lamin mutants on the distribution of heterochromatin protein 1 (HP1) isoforms. HeLa cells expressing these mutants showed a heterogeneous pattern of HP1alpha and beta depletion but without altering HP1gamma levels. Changes in HP1alpha and beta were not observed in cells expressing wild-type lamin A or mutant R482L, which assembled normally at the nuclear rim. Treatment with proteasomal inhibitors led to restoration of levels of HP1 isoforms and also resulted in stable association of lamin mutants with the nuclear periphery, rim localization of the inner nuclear membrane lamin-binding protein emerin and partial improvement of nuclear morphology. A comparison of the stability of HP1 isoforms indicated that HP1alpha and beta displayed increased turnover and higher basal levels of ubiquitination than HP1gamma. Transcript analysis of components of the ubiquitination pathway showed that a specific F-box protein, FBXW10 was induced several-fold in cells expressing lamin mutants. Importantly, ectopic expression of FBXW10 in HeLa cells led to depletion of HP1alpha and beta without alteration of HP1gamma levels. CONCLUSIONS Mislocalized lamins can induce ubiquitin-mediated proteasomal degradation of certain HP1 isoforms by activation of FBXW10, a member of the F-box family of proteins that is involved in E3 ubiquitin ligase activity.
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Affiliation(s)
| | - Veena K. Parnaik
- Centre for Cellular and Molecular Biology (CSIR), Hyderabad, India
- * E-mail:
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35
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Gurudatta BV, Shashidhara LS, Parnaik VK. Lamin C and chromatin organization in Drosophila. J Genet 2010; 89:37-49. [DOI: 10.1007/s12041-010-0009-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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36
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Vogl AW, Vaid KS, Guttman JA. The Sertoli cell cytoskeleton. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 636:186-211. [PMID: 19856169 DOI: 10.1007/978-0-387-09597-4_11] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The cytoskeleton of terminally differentiated mammalian Sertoli cells is one of the most elaborate of those that have been described for cells in tissues. Actin filaments, intermediate filaments and microtubules have distinct patterns of distribution that change during the cyclic process of spermatogenesis. Each of the three major cytoskeletal elements is either concentrated at or related in part to intercellular junctions. Actin filaments are concentrated in unique structures termed ectoplasmic specializations that function in intercellular adhesion, and at tubulobulbar complexes that are thought to be involved with junction internalization during sperm release and movement of spermatocytes through basal junctions between neighboring Sertoi cells. Intermediate filaments occur in a perinuclear network which has peripheral extensions to desmosome-like junctions with adjacent cells and to small hemidesmosome-like attachments to the basal lamina. Unlike in most other epithelia where the intermediate filaments are of the keratin type, intermediate filaments in mature Sertoli cells are of the vimentin type. The function of intermediate filaments in Sertoli cells in not entirely clear; however, the pattern of filament distribution and the limited experimental data available are consistent with a role in maintaining tissue integrity when the epithelium is mechanically stressed. Microtubules are abundant in Sertoli cells and are predominantly oriented parallel to the long axis of the cell. Microtubules are involved with maintaining the columnar shape of Sertoli cells, with transporting and positioning organelles in the cytoplasm, and with secreting seminiferous tubule fluid. In addition, microtubule-based transport machinery is coupled to intercellular junctions to translocate and position adjacent spermatids in the epithelium. Although the cytoskeleton of Sertoli cells has structural and functional properties common to cells generally, there are a number of properties that are unique and that appear related to processes fundamental to spermatogenesis and to interfacing somatic cells both with similar neighboring somatic cells and with differentiating cells of the germ cell line.
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Affiliation(s)
- A Wayne Vogl
- Department of Cellular and Physiological Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
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Garcia-Arocena D, Yang JE, Brouwer JR, Tassone F, Iwahashi C, Berry-Kravis EM, Goetz CG, Sumis AM, Zhou L, Nguyen DV, Campos L, Howell E, Ludwig A, Greco C, Willemsen R, Hagerman RJ, Hagerman PJ. Fibroblast phenotype in male carriers of FMR1 premutation alleles. Hum Mol Genet 2009; 19:299-312. [PMID: 19864489 DOI: 10.1093/hmg/ddp497] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder among carriers of premutation expansions (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene. The clinical features of FXTAS, as well as various forms of clinical involvement in carriers without FXTAS, are thought to arise through a direct toxic gain of function of high levels of FMR1 mRNA containing the expanded CGG repeat. Here we report a cellular endophenotype involving increased stress response (HSP27, HSP70 and CRYAB) and altered lamin A/C expression/organization in cultured skin fibroblasts from 11 male carriers of premutation alleles of the FMR1 gene, including six patients with FXTAS and five premutation carriers with no clinical evidence of FXTAS, compared with six controls. A similar abnormal cellular phenotype was found in CNS tissue from 10 patients with FXTAS. Finally, there is an analogous abnormal cellular distribution of lamin A/C isoforms in knock-in mice bearing the expanded CGG repeat in the murine Fmr1 gene. These alterations are evident even in mouse embryonic fibroblasts, raising the possibility that, in humans, the expanded-repeat mRNA triggers pathogenic mechanisms early in development, thus providing a molecular basis for the neurodevelopmental abnormalities observed in some children and clinical symptoms in some adults who are carriers of premutation FMR1 alleles. Cellular dysregulation in fibroblasts represents a novel and highly advantageous model for investigating disease pathogenesis in premutation carriers and for quantifying and monitoring disease progression. Fibroblast studies may also prove useful in screening and testing the efficacy of therapeutic interventions.
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Affiliation(s)
- Dolores Garcia-Arocena
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, CA 95616, USA
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Chen S, Martin C, Maya-Mendoza A, Tang CW, Lovrić J, Sims PFG, Jackson DA. Reduced Expression of Lamin A/C Results in Modified Cell Signaling and Metabolism Coupled with Changes in Expression of Structural Proteins. J Proteome Res 2009; 8:5196-211. [DOI: 10.1021/pr900549a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Songbi Chen
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Catherine Martin
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Apolinar Maya-Mendoza
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Chi W. Tang
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Josip Lovrić
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Paul F. G. Sims
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Dean A. Jackson
- Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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Datta K, Guan T, Gerace L. NET37, a nuclear envelope transmembrane protein with glycosidase homology, is involved in myoblast differentiation. J Biol Chem 2009; 284:29666-76. [PMID: 19706595 DOI: 10.1074/jbc.m109.034041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The nuclear lamina and its associated proteins are important for nuclear structure and chromatin organization and also have been implicated in the regulation of cell signaling and gene expression. In this study we demonstrate that the lamina-associated nuclear envelope transmembrane protein NET37 is required for myogenic differentiation of C2C12 cells. NET37, a member of glycosidase family 31, is highly expressed in mouse skeletal muscle and is strongly up-regulated during C2C12 differentiation. By protease mapping we show that its glycosidase homology domain is located in the lumen of the nuclear envelope/endoplasmic reticulum. When NET37 is depleted from proliferating myoblasts by RNAi, myogenic differentiation is significantly impaired, and there is a concomitant delay in up-regulation of the late myogenic transcription factor myogenin. We expressed silencing-resistant NET37 mutated at a conserved residue in the glycosidase domain and found that this predicted catalytically inactive protein is unable to support myogenesis in cells depleted of wild type NET37. Therefore, the enzymatic function of NET37 appears to be important for myogenic differentiation. C2C12 cells depleted of NET37 have reduced activation of Akt after shifting to differentiation medium and are defective in insulin like growth factor-II (IGF-II) secretion, an autocrine/paracrine factor involved in Akt activation. We also observed that pro-IGF-II co-immunoprecipitates with NET37. Based on our results, we propose that NET37 has a role in IGF-II maturation in the secretory pathway during myoblast differentiation. The localization of NET37 at the nuclear envelope raises the possibility that it may coordinate myogenic events between the nuclear interior and the endoplasmic reticulum lumen via transmembrane communication.
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Affiliation(s)
- Kaustuv Datta
- Department of Cell Biology and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Buch C, Lindberg R, Figueroa R, Gudise S, Onischenko E, Hallberg E. An integral protein of the inner nuclear membrane localizes to the mitotic spindle in mammalian cells. J Cell Sci 2009; 122:2100-7. [DOI: 10.1242/jcs.047373] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Here, we characterize a transmembrane protein of the nuclear envelope that we name spindle-associated membrane protein 1 (Samp1). The protein is conserved in metazoa and fission yeast and is homologous to Net5 in rat and Ima1 in Schizosaccharomyces pombe. We show that, in human cells, the protein is a membrane-spanning polypeptide with an apparent molecular mass of 43 kDa. This is consistent with a predicted polypeptide of 392 amino acids that has five transmembrane segments and its C-terminus exposed to the nucleoplasm. During interphase, Samp1 was specifically distributed in the inner nuclear membrane. Post-transcriptional silencing of Samp1 expression resulted in separation of centrosomes from the nuclear envelope, indicating that it is functionally connected to the cytoskeleton. At the onset of mitosis, most of the protein dispersed out into the ER, as expected. However, during mitosis, a significant fraction of the protein specifically localized to the polar regions of the mitotic spindle. We demonstrate for the first time, in human cells, the existence of a membranous structure overlapping with the mitotic spindle. Interestingly, another integral inner nuclear membrane protein, emerin, was absent from the spindle-associated membranes. Thus, Samp1 defines a specific membrane domain associated with the mitotic spindle.
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Affiliation(s)
- Charlotta Buch
- Department of Biosciences and Nutrition, Karolinska Institute, SE-141 57 Huddinge, Sweden
- Life Sciences, Södertörns University, SE-141 89 Huddinge, Sweden
| | - Robert Lindberg
- Life Sciences, Södertörns University, SE-141 89 Huddinge, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ricardo Figueroa
- Life Sciences, Södertörns University, SE-141 89 Huddinge, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Santhosh Gudise
- Department of Biosciences and Nutrition, Karolinska Institute, SE-141 57 Huddinge, Sweden
- Life Sciences, Södertörns University, SE-141 89 Huddinge, Sweden
| | - Evgeny Onischenko
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Einar Hallberg
- Life Sciences, Södertörns University, SE-141 89 Huddinge, Sweden
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Martin C, Chen S, Maya-Mendoza A, Lovric J, Sims PFG, Jackson DA. Lamin B1 maintains the functional plasticity of nucleoli. J Cell Sci 2009; 122:1551-62. [PMID: 19383719 PMCID: PMC2722682 DOI: 10.1242/jcs.046284] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2009] [Indexed: 01/14/2023] Open
Abstract
The dynamic ability of genomes to interact with discrete nuclear compartments appears to be essential for chromatin function. However, the extent to which structural nuclear proteins contribute to this level of organization is largely unresolved. To test the links between structure and function, we evaluated how nuclear lamins contribute to the organization of a major functional compartment, the nucleolus. HeLa cells with compromised expression of the genes encoding lamins were analyzed using high-resolution imaging and pull-down assays. When lamin B1 expression was depleted, inhibition of RNA synthesis correlated with complex structural changes within the nucleolar active centers until, eventually, the nucleoli were dispersed completely. With normal lamin expression, the nucleoli were highly plastic, with dramatic and freely reversible structural changes correlating with the demand for ribosome biogenesis. Preservation of the nucleolar compartment throughout these structural transitions is shown to be linked to lamin B1 expression, with the lamin B1 protein interacting with the major nucleolar protein nucleophosmin/B23.
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Affiliation(s)
- Catherine Martin
- Faculty of Life Sciences, University of Manchester, MIB, 131 Princess Street, Manchester M1 7DN, UK
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de Carlos F, Varela I, Germanà A, Montalbano G, Freije JMP, Vega JA, López-Otin C, Cobo JM. Microcephalia with mandibular and dental dysplasia in adult Zmpste24-deficient mice. J Anat 2009; 213:509-19. [PMID: 19014358 DOI: 10.1111/j.1469-7580.2008.00970.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
ZMPSTE24 (also called FACE-1) is a zinc-metalloprotease involved in the post-translational processing of prelamin A to mature lamin A, a major component of the nuclear envelope. Mutations in the ZMPSTE24 gene or in that encoding its substrate prelamin A (LMNA) result in a series of human inherited diseases known collectively as laminopathies and showing regional or systemic manifestations (i.e. the Hutchinson-Gilford progeria syndrome). Typically, patients suffering some laminopathies show craniofacial or mandible anomalies, aberrant dentition or facial features characteristic of aged persons. To analyse whether Zmpste24(-/-) mice reproduce the cranial phenotype observed in humans due to mutations in ZMPSTE24 or LMNA, we conducted a craniometric study based on micro-computer tomography (microCT) images. Furthermore, using simple radiology, microCT, microCT-densitometry and scanning electron microscopy, we analysed the mandible and the teeth from Zmpste24(-/-) mice. Finally, the structure of the lower incisor was investigated using an H&E technique. The results demonstrate that Zmpste24(-/-) mice are microcephalic and show mandibular and dental dysplasia affecting only the mandible teeth. In all cases, the lower incisor of mice lacking Zmpste24 was smaller than in control animals, showed cylindrical morphology and a transverse fissure at the incisal edge, and the pulpal cavity was severely reduced. Structurally, the dental layers were normally arranged but cellular layers were disorganized. The inferior molars showed a reduced cusp size. Taken together, these data strongly suggest that Zmpste24(-/-) mice represent a good model to analyse the craniofacial and teeth malformations characteristic of lamin-related pathologies, and might contribute to a better understanding of the molecular events underlying these diseases.
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Affiliation(s)
- F de Carlos
- Departamentos de Cirugía y Especialidades Médico-Quirúrgicas (Area de Estomatología), Universidad de Oviedo, Spain
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Malhas AN, Lee CF, Vaux DJ. Lamin B1 controls oxidative stress responses via Oct-1. J Cell Biol 2009; 184:45-55. [PMID: 19139261 PMCID: PMC2615091 DOI: 10.1083/jcb.200804155] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Accepted: 12/11/2008] [Indexed: 12/14/2022] Open
Abstract
Interaction of lamins with chromatin and transcription factors regulate transcription. Oct-1 has previously been shown to colocalize partly with B-type lamins and is essential for transcriptional regulation of oxidative stress response genes. Using sequential extraction, co-immunoprecipitation (IP), fluorescence loss in photobleaching, and fluorescence resonance energy transfer, we confirm Oct-1-lamin B1 association at the nuclear periphery and show that this association is lost in Lmnb1(Delta/Delta) cells. We show that several Oct-1-dependent genes, including a subset involved in oxidative stress response, are dysregulated in Lmnb1(Delta/Delta) cells. Electrophoretic mobility shift assay and chromatin IP reveal that Oct-1 binds to the putative octamer-binding sequences of the dysregulated genes and that this activity is increased in cells lacking functional lamin B1. Like Oct1(-/-) cells, Lmnb1(Delta/Delta) cells have elevated levels of reactive oxygen species and are more susceptible to oxidative stress. Sequestration of Oct-1 at the nuclear periphery by lamin B1 may be a mechanism by which the nuclear envelope can regulate gene expression and contribute to the cellular response to stress, development, and aging.
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Affiliation(s)
- Ashraf N Malhas
- Department of Physics, Sir William Dunn School of Pathology, University of Oxford, Oxford, England, UK
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Ben-Harush K, Wiesel N, Frenkiel-Krispin D, Moeller D, Soreq E, Aebi U, Herrmann H, Gruenbaum Y, Medalia O. The supramolecular organization of the C. elegans nuclear lamin filament. J Mol Biol 2008; 386:1392-402. [PMID: 19109977 DOI: 10.1016/j.jmb.2008.12.024] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2008] [Accepted: 12/09/2008] [Indexed: 11/26/2022]
Abstract
Nuclear lamins are involved in most nuclear activities and are essential for retaining the mechano-elastic properties of the nucleus. They are nuclear intermediate filament (IF) proteins forming a distinct meshwork-like layer adhering to the inner nuclear membrane, called the nuclear lamina. Here, we present for the first time, the three-dimensional supramolecular organization of lamin 10 nm filaments and paracrystalline fibres. We show that Caenorhabditis elegans nuclear lamin forms 10 nm IF-like filaments, which are distinct from their cytoplasmic counterparts. The IF-like lamin filaments are composed of three and four tetrameric protofilaments, each of which contains two partially staggered anti-parallel head-to-tail polymers. The beaded appearance of the lamin filaments stems from paired globular tail domains, which are spaced regularly, alternating between 21 nm and 27 nm. A mutation in an evolutionarily conserved residue that causes Hutchison-Gilford progeria syndrome in humans alters the supramolecular structure of the lamin filaments. On the basis of our structural analysis, we propose an assembly pathway that yields the observed 10 nm IF-like lamin filaments and paracrystalline fibres. These results serve also as a platform for understanding the effect of laminopathic mutations on lamin supramolecular organization.
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Affiliation(s)
- Kfir Ben-Harush
- Department of Life Sciences, Ben Gurion University and the NIBN, Beer-Sheva, 84120 Israel
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Ishimura A, Chida S, Osada SI. Man1, an inner nuclear membrane protein, regulates left-right axis formation by controlling nodal signaling in a node-independent manner. Dev Dyn 2008; 237:3565-76. [DOI: 10.1002/dvdy.21663] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Zwerger M, Herrmann H, Gaines P, Olins AL, Olins DE. Granulocytic nuclear differentiation of lamin B receptor-deficient mouse EPRO cells. Exp Hematol 2008; 36:977-87. [PMID: 18495328 PMCID: PMC2547467 DOI: 10.1016/j.exphem.2008.03.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2008] [Revised: 03/06/2008] [Accepted: 03/07/2008] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Lamin B receptor (LBR) is an integral protein of the inner nuclear membrane. Recent studies have demonstrated that genetic deficiency of LBR during granulopoiesis results in hypolobulation of the mature neutrophil nucleus, as observed in human Pelger-Huët anomaly and mouse ichthyosis (ic). In this study, we utilized differentiated early promyelocytes (EPRO cells) that were derived from the bone marrow of homozygous and heterozygous ichthyosis mice to examine changes to the expression of nuclear envelope proteins and heterochromatin structure that result from deficient LBR expression. MATERIALS AND METHODS Wild-type (+/+), heterozygous (+/ic), and homozygous (ic/ic) granulocytic forms of EPRO cells were analyzed for the expression of multiple lamins and inner nuclear envelope proteins by immunostaining and immunoblotting techniques. The heterochromatin architecture was also examined by immunostaining for histone lysine methylation. RESULTS Wild-type (+/+) and heterozygous (+/ic) granulocytic forms revealed ring-shaped nuclei and contained LBR within the nuclear envelope; ic/ic granulocytes exhibited smaller ovoid nuclei devoid of LBR. The pericentric heterochromatin of undifferentiated and granulocytic ic/ic cells was condensed into larger spots and shifted away from the nuclear envelope, compared to +/+ and +/ic cell forms. Lamin A/C, which is normally not present in mature granulocytes, was significantly elevated in LBR-deficient EPRO cells. CONCLUSIONS Our observations suggest roles for LBR during granulopoiesis, which can involve augmenting nuclear membrane growth, facilitating compartmentalization of heterochromatin, and promoting downregulation of lamin A/C expression.
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Affiliation(s)
- Monika Zwerger
- B065, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Harald Herrmann
- B065, German Cancer Research Center, Heidelberg, D-69120, Germany
| | - Peter Gaines
- Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA 01854
| | - Ada L. Olins
- Department of Biology, Bowdoin College, Brunswick, ME 04101
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Haraguchi T, Kojidani T, Koujin T, Shimi T, Osakada H, Mori C, Yamamoto A, Hiraoka Y. Live cell imaging and electron microscopy reveal dynamic processes of BAF-directed nuclear envelope assembly. J Cell Sci 2008; 121:2540-54. [PMID: 18628300 DOI: 10.1242/jcs.033597] [Citation(s) in RCA: 165] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Assembly of the nuclear envelope (NE) in telophase is essential for higher eukaryotic cells to re-establish a functional nucleus. Time-lapse, FRAP and FRET analyses in human cells showed that barrier-to-autointegration factor (BAF), a DNA-binding protein, assembled first at the distinct ;core' region of the telophase chromosome and formed an immobile complex by directly binding with other core-localizing NE proteins, such as lamin A and emerin. Correlative light and electron microscopy after live cell imaging, further showed that BAF formed an electron-dense structure on the chromosome surface of the core, close to spindle microtubules (MTs) prior to the attachment of precursor NE membranes, suggesting that MTs may mediate core assembly of BAF. Disruption of the spindle MTs consistently abolished BAF accumulation at the core. In addition, RNAi of BAF eliminated the core assembly of lamin A and emerin, caused abnormal cytoplasmic accumulation of precursor nuclear membranes and resulted in a significant delay of NE assembly. These results suggest that the MT-mediated BAF accumulation at the core facilitates NE assembly at the end of mitosis.
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Affiliation(s)
- Tokuko Haraguchi
- CREST Research Project, Kobe Advanced ICT Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, Japan.
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The nuclear envelope as an integrator of nuclear and cytoplasmic architecture. FEBS Lett 2008; 582:2023-32. [PMID: 18474238 DOI: 10.1016/j.febslet.2008.05.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 05/02/2008] [Accepted: 05/05/2008] [Indexed: 12/11/2022]
Abstract
Initially perceived as little more than a container for the genome, our view of the nuclear envelope (NE) and its role in defining global nuclear architecture has evolved significantly in recent years. The recognition that certain human diseases arise from defects in NE components has provided new insight into its structural and regulatory functions. In particular, NE defects associated with striated muscle disease have been shown to cause structural perturbations not just of the nucleus itself but also of the cytoplasm. It is now becoming increasingly apparent that these two compartments display co-dependent mechanical properties. The identification of cytoskeletal binding complexes that localize to the NE now reveals a molecular framework that can seamlessly integrate nuclear and cytoplasmic architecture.
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Strnad P, Tao GZ, Zhou Q, Harada M, Toivola DM, Brunt EM, Omary MB. Keratin mutation predisposes to mouse liver fibrosis and unmasks differential effects of the carbon tetrachloride and thioacetamide models. Gastroenterology 2008; 134:1169-79. [PMID: 18395095 PMCID: PMC2692280 DOI: 10.1053/j.gastro.2008.01.035] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 01/04/2008] [Indexed: 01/07/2023]
Abstract
BACKGROUND & AIMS Keratins 8 and 18 (K8/K18) are important hepatoprotective proteins. Animals expressing K8/K18 mutants show a marked susceptibility to acute/subacute liver injury. K8/K18 variants predispose to human end-stage liver disease and associate with fibrosis progression during chronic hepatitis C infection. We sought direct evidence for a keratin mutation-related predisposition to liver fibrosis using transgenic mouse models because the relationship between keratin mutations and cirrhosis is based primarily on human association studies. METHODS Mouse hepatofibrosis was induced by carbon tetrachloride (CCl(4)) or thioacetamide. Nontransgenic mice, or mice that over express either human Arg89-to-Cys (R89C mice) or wild-type K18 (WT mice) were used. The extent of fibrosis was evaluated by quantitative real-time reverse-transcription polymerase chain reaction of fibrosis-related genes, liver hydroxyproline measurement, and Picro-Sirius red staining and collagen immunofluorescence staining. RESULTS Compared with control animals, CCl(4) led to similar liver fibrosis but increased injury in K18 R89C mice. In contrast, thioacetamide caused more severe liver injury and fibrosis in K18 R89C as compared with WT and nontransgenic mice and resulted in increased messenger RNA levels of collagen, tissue inhibitor of metalloproteinase 1, matrix metalloproteinase 2, and matrix metalloproteinase 13. Analysis in nontransgenic mice showed that thioacetamide and CCl(4) have dramatically different molecular expression responses involving cytoskeletal and chaperone proteins. CONCLUSIONS Over expression of K18 R89C predisposes transgenic mice to thioacetamide- but not CCl(4)-induced liver fibrosis. Differences in the keratin mutation-associated fibrosis response among the 2 models raise the hypothesis that keratin variants may preferentially predispose to fibrosis in unique human liver diseases. Findings herein highlight distinct differences in the 2 widely used fibrosis models.
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Affiliation(s)
| | | | | | - Masaru Harada
- Department of Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan
| | | | - Elizabeth M. Brunt
- Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Ave, Campus Box 8118, St. Louis, MO 63110
| | - M. Bishr Omary
- Corresponding Author Address: Bishr Omary, Palo Alto VA Medical Center, 3801 Miranda Avenue, Mail code 154J, Palo Alto, CA 94304, Tel: (650) 493-5000, x63140; Fax: (650) 852-3259, E-Mail:
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