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Lämmerhirt L, Kappelmann-Fenzl M, Fischer S, Meier P, Staebler S, Kuphal S, Bosserhoff AK. Loss of miR-101-3p in melanoma stabilizes genomic integrity, leading to cell death prevention. Cell Mol Biol Lett 2024; 29:29. [PMID: 38431560 PMCID: PMC10909299 DOI: 10.1186/s11658-024-00552-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 02/21/2024] [Indexed: 03/05/2024] Open
Abstract
Malignant melanoma remains the most lethal form of skin cancer, exhibiting poor prognosis after forming distant metastasis. Owing to their potential tumor-suppressive properties by regulating oncogenes and tumor suppressor genes, microRNAs are important player in melanoma development and progression. We defined the loss of miR-101-3p expression in melanoma cells compared with melanocytes and melanoblast-related cells as an early event in tumor development and aimed to understand the tumor suppressive role of miR-101-3p and its regulation of important cellular processes. Reexpression of miR-101-3p resulted in inhibition of proliferation, increase in DNA damage, and induction of apoptosis. We further determined the nuclear structure protein Lamin B1, which influences nuclear processes and heterochromatin structure, ATRX, CASP3, and PARP as an important direct target of miR-101-3p. RNA sequencing and differential gene expression analysis after miR-101-3p reexpression supported our findings and the importance of loss of mir-101-3p for melanoma progression. The validated functional effects are related to genomic instability, as recent studies suggest miRNAs plays a key role in mediating this cellular process. Therefore, we concluded that miR-101-3p reexpression increases the genomic instability, leading to irreversible DNA damage, which leads to apoptosis induction. Our findings suggest that the loss of miR-101-3p in melanoma serves as an early event in melanoma progression by influencing the genomic integrity to maintain the increased bioenergetic demand.
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Affiliation(s)
- Lisa Lämmerhirt
- Institute of Biochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054, Erlangen, Germany
| | - Melanie Kappelmann-Fenzl
- Faculty of Computer Science, Deggendorf Institute of Technology, Dieter-Görlitz-Platz 1, 94469, Deggendorf, Germany
| | - Stefan Fischer
- Faculty of Computer Science, Deggendorf Institute of Technology, Dieter-Görlitz-Platz 1, 94469, Deggendorf, Germany
| | - Paula Meier
- Institute of Biochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054, Erlangen, Germany
- Julius-Maximilians-University Würzburg (JMU), Sanderring 2, 97070, Würzburg, Germany
| | - Sebastian Staebler
- Institute of Biochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054, Erlangen, Germany
| | - Silke Kuphal
- Institute of Biochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054, Erlangen, Germany
| | - Anja-Katrin Bosserhoff
- Institute of Biochemistry, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Fahrstraße 17, 91054, Erlangen, Germany.
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Li Y, Bertozzi A, Mann MRW, Kühn B. Interdependent changes of nuclear lamins, nuclear pore complexes, and ploidy regulate cellular regeneration and stress response in the heart. Nucleus 2023; 14:2246310. [PMID: 37606283 PMCID: PMC10446781 DOI: 10.1080/19491034.2023.2246310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 07/28/2023] [Accepted: 08/04/2023] [Indexed: 08/23/2023] Open
Abstract
In adult mammals, many heart muscle cells (cardiomyocytes) are polyploid, do not proliferate (post-mitotic), and, consequently, cannot contribute to heart regeneration. In contrast, fetal and neonatal heart muscle cells are diploid, proliferate, and contribute to heart regeneration. We have identified interdependent changes of the nuclear lamina, nuclear pore complexes, and DNA-content (ploidy) in heart muscle cell maturation. These results offer new perspectives on how cells alter their nuclear transport and, with that, their gene regulation in response to extracellular signals. We present how changes of the nuclear lamina alter nuclear pore complexes in heart muscle cells. The consequences of these changes for cellular regeneration and stress response in the heart are discussed.
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Affiliation(s)
- Yao Li
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alberto Bertozzi
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Mellissa RW Mann
- Department of Obstetrics, Gynaecology and Reproductive Sciences, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Magee-Womens Research Institute, Pittsburgh, PA, USA
| | - Bernhard Kühn
- Division of Pediatric Cardiology, Pediatric Institute for Heart Regeneration and Therapeutics (I-HRT), UPMC Children’s Hospital of Pittsburgh, Pittsburgh, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- McGowan Institute of Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Knockdown of Lamin B1 and the Corresponding Lamin B Receptor Leads to Changes in Heterochromatin State and Senescence Induction in Malignant Melanoma. Cells 2022; 11:cells11142154. [PMID: 35883595 PMCID: PMC9321645 DOI: 10.3390/cells11142154] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/02/2022] [Accepted: 07/05/2022] [Indexed: 11/17/2022] Open
Abstract
Modifications in nuclear structures of cells are implicated in several diseases including cancer. They result in changes in nuclear activity, structural dynamics and cell signalling. However, the role of the nuclear lamina and related proteins in malignant melanoma is still unknown. Its molecular characterisation might lead to a deeper understanding and the development of new therapy approaches. In this study, we analysed the functional effects of dysregulated nuclear lamin B1 (LMNB1) and its nuclear receptor (LBR). According to their cellular localisation and function, we revealed that these genes are crucially involved in nuclear processes like chromatin organisation. RNA sequencing and differential gene expression analysis after knockdown of LMNB1 and LBR revealed their implication in important cellular processes driving ER stress leading to senescence and changes in chromatin state, which were also experimentally validated. We determined that melanoma cells need both molecules independently to prevent senescence. Hence, downregulation of both molecules in a BRAFV600E melanocytic senescence model as well as in etoposide-treated melanoma cells indicates both as potential senescence markers in melanoma. Our findings suggest that LMNB1 and LBR influence senescence and affect nuclear processes like chromatin condensation and thus are functionally relevant for melanoma progression.
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Myocardial and Arrhythmic Spectrum of Neuromuscular Disorders in Children. Biomolecules 2021; 11:biom11111578. [PMID: 34827576 PMCID: PMC8615674 DOI: 10.3390/biom11111578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/02/2021] [Accepted: 10/14/2021] [Indexed: 12/30/2022] Open
Abstract
Neuromuscular disorders (NMDs) are highly heterogenous from both an etiological and clinical point of view. Their signs and symptoms are often multisystemic, with frequent cardiac involvement. In fact, childhood onset forms can predispose a person to various progressive cardiac abnormalities including cardiomyopathies (CMPs), valvulopathies, atrioventricular conduction defects (AVCD), supraventricular tachycardia (SVT) and ventricular arrhythmias (VA). In this review, we selected and described five specific NMDs: Friedreich’s Ataxia (FRDA), congenital and childhood forms of Myotonic Dystrophy type 1 (DM1), Kearns Sayre Syndrome (KSS), Ryanodine receptor type 1-related myopathies (RYR1-RM) and Laminopathies. These changes are widely investigated in adults but less researched in children. We focused on these specific topics due their relative frequency and their potential unexpected cardiac manifestations in children. Moreover these conditions present different inheritance patterns and mechanisms of action. We decided not to discuss Duchenne and Becker muscular dystrophies due to extensive work regarding the cardiac aspects in children. For each described NMD, we focused on the possible cardiac manifestations such as different types of CMPs (dilated-DCM, hypertrophic-HCM, restrictive-RCM or left ventricular non compaction-LVNC), structural heart abnormalities (including valvulopathies), and progressive heart rhythm changes (AVCD, SVT, VA). We describe the current management strategies for these conditions. We underline the importance, especially for children, of a serial multidisciplinary personalized approach and the need for periodic surveillance by a dedicated heart team. This is largely due to the fact that in children, the diagnosis of certain NMDs might be overlooked and the cardiac aspect can provide signs of their presence even prior to overt neurological diagnosis.
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Lee CP, Chen MR. Conquering the Nuclear Envelope Barriers by EBV Lytic Replication. Viruses 2021; 13:702. [PMID: 33919628 PMCID: PMC8073350 DOI: 10.3390/v13040702] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 12/14/2022] Open
Abstract
The nuclear envelope (NE) of eukaryotic cells has a highly structural architecture, comprising double lipid-bilayer membranes, nuclear pore complexes, and an underlying nuclear lamina network. The NE structure is held in place through the membrane-bound LINC (linker of nucleoskeleton and cytoskeleton) complex, spanning the inner and outer nuclear membranes. The NE functions as a barrier between the nucleus and cytoplasm and as a transverse scaffold for various cellular processes. Epstein-Barr virus (EBV) is a human pathogen that infects most of the world's population and is associated with several well-known malignancies. Within the nucleus, the replicated viral DNA is packaged into capsids, which subsequently egress from the nucleus into the cytoplasm for tegumentation and final envelopment. There is increasing evidence that viral lytic gene expression or replication contributes to the pathogenesis of EBV. Various EBV lytic proteins regulate and modulate the nuclear envelope structure in different ways, especially the viral BGLF4 kinase and the nuclear egress complex BFRF1/BFRF2. From the aspects of nuclear membrane structure, viral components, and fundamental nucleocytoplasmic transport controls, this review summarizes our findings and recently updated information on NE structure modification and NE-related cellular processes mediated by EBV.
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Affiliation(s)
- Chung-Pei Lee
- School of Nursing, National Taipei University of Nursing and Health Sciences, Taipei 112303, Taiwan;
| | - Mei-Ru Chen
- Graduate Institute and Department of Microbiology, College of Medicine, National Taiwan University, Taipei 100233, Taiwan
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Finol HJ, Garcia-Lunardi E, González R, Girón ME, Uzcátegui NL, Rodríguez-Acosta A. Qualitative and Quantitative Study of the Changes in the Ultrastructure of Mammalian Adrenal Cortex Caused by the Venezuelan Tigra Mariposa ( Bothrops venezuelensis) Snake Venom. J Microsc Ultrastruct 2020; 8:104-114. [PMID: 33282685 PMCID: PMC7703017 DOI: 10.4103/jmau.jmau_49_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 05/09/2020] [Indexed: 12/03/2022] Open
Abstract
The damage of the adrenal gland by snake venoms needs to be clarified. Lethality (LD50) of Bothrops venezuelensis (Bv) venom was established by intraperitoneally mice injections. Preparation of specimens for transmission electron microscopy samples from cortex adrenal gland biopsies at 3, 6, and 24 h was processed. The quantitative description by the principal component analysis (PCA) of the adrenal gland was as follows: thickening of the capillary endothelium, area of the capillary lumen, cell nucleus area, enlargement of the perinuclear space, number of mitochondria, area of the mitochondria, number of mitochondrial cristae, number of cristae per mitochondrial unit, and tubular diameter of the smooth endoplasmic reticulum (SER). Sections of the adrenal cortex, after 3 h postinjection with Bv venom showed in the cortical cells: mitochondria with tubular cristae and slightly swollen SER cisternae, nucleus with variable heterochromatin content, irregular edges, and swollen nuclear envelope. After 6 h, cells with swollen nucleus envelope, electron dense lipids and mitochondria with loss of their cristae were observed. Myelin figures, close to the microvilli of the cortical cell, multivesicular bodies, swollen profiles of the SER, and electron dense lipid drops were noticed. After 24 h, thickening of the endothelial wall, fenestrae and projections into the capillary lumen, loss of the mitochondrial cristae, destruction of the capillary and the plasma membrane of the cortical cell, multivesicular body, SER loss, and an enlargement of the perinuclear space were detected. In the quantitative PCA, there were significant changes after the venom treatments.
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Affiliation(s)
- Héctor J Finol
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Estefanie Garcia-Lunardi
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Roschman González
- Microscopy Electronic Centre, Faculty of Sciences, Universidad Central De Venezuela, Caracas, Venezuela
| | - Maria E Girón
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
| | - Nestor L Uzcátegui
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
| | - Alexis Rodríguez-Acosta
- Anatomical Institute, Immunochemistry and Ultrastructure Laboratory, Universidad Central De Venezuela, Caracas, Venezuela
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Baban A, Cicenia M, Magliozzi M, Gnazzo M, Cantarutti N, Silvetti MS, Adorisio R, Dallapiccola B, Bertini E, Novelli A, Drago F. Cardiovascular Involvement in Pediatric Laminopathies. Report of Six Patients and Literature Revision. Front Pediatr 2020; 8:374. [PMID: 32793522 PMCID: PMC7393225 DOI: 10.3389/fped.2020.00374] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 06/02/2020] [Indexed: 12/30/2022] Open
Abstract
Lamin A/C (LMNA) encodes for two nuclear intermediate filament proteins. Mutations in LMNA cause a highly heterogeneous group of diseases predominantly leading to muscular or cardiac disease, lipodystrophy syndromes, peripheral neuropathy, and accelerated aging disorders. Cardiac involvement includes progressive arrhythmias (brady/tachyarrhythmias, sudden cardiac death). Furthermore, cardiomyocyte damage often progresses into dilated cardiomyopathy (DCM), rarely described in the pediatric age group. Neuromuscular manifestations are even rarer in children. We report on six pediatric patients with LMNA mutations: patient 1 was operated on for aortic coarctation, non-compact left ventricle, atrial fibrillation (AF) preceding the diagnosis of DCM; patient 2 was operated on for ventricular septal defect (VSD), developed after years malignant arrhythmias preceding the progression to DCM (left ventricular non-compaction with LV dysfunction); patient 3 had ectopic atrial tachycardia as first manifestation of a DCM; patients 4 and 5 had no major arrhythmic events but only dilated ascending aorta, mildly dilated LV with mild hypertrabeculation of the lateral wall and a normally functioning but dilated left ventricle, respectively; patient 6 showed aortic coarctation, supraventricular tachycardia. Paroxysmal AF occurred in patients 1, 2, and 3 (50% of cases). Our series highlight the coexistence of congenital heart defects (CHDs) and aortic involvement with laminopathies in four of our patients: consisting of aortic coarctation (two patients), aortic root dilatation (one patient), and VSD (one patient). Aortic changes in laminopathies have been reported only once in an adult patient. This is the first report in the pediatric setting, and no associations with CHD have been previously described.
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Affiliation(s)
- Anwar Baban
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Marianna Cicenia
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Monia Magliozzi
- Laboratory of Medical Genetics, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Maria Gnazzo
- Laboratory of Medical Genetics, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Nicoletta Cantarutti
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Massimo Stefano Silvetti
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Rachele Adorisio
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Bruno Dallapiccola
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Enrico Bertini
- The European Reference Network for Neuromuscular Disorders (ERN NMD), Unit of Neuromuscular and Neurodegenerative Disorders, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Fabrizio Drago
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart-ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
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Sui T, Liu D, Liu T, Deng J, Chen M, Xu Y, Song Y, Ouyang H, Lai L, Li Z. LMNA-mutated Rabbits: A Model of Premature Aging Syndrome with Muscular Dystrophy and Dilated Cardiomyopathy. Aging Dis 2019; 10:102-115. [PMID: 30705772 PMCID: PMC6345340 DOI: 10.14336/ad.2018.0209] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/09/2018] [Indexed: 12/13/2022] Open
Abstract
Premature aging syndromes are rare genetic disorders mimicking clinical and molecular features of aging. Products of the LMNA gene, primarily lamin A and C, are major components of the nuclear lamina. A recently identified group of premature aging syndromes was related to mutations of the LMNA gene. Although LMNA disorders have been identified in premature aging syndromes, affect specifically the skeletal muscles, cardiac muscles, and lipodystrophy, understanding the pathogenic mechanisms still need to be elucidated. Here, to establish a rabbit knockout (KO) model of premature aging syndromes, we performed precise LMNA targeting in rabbits via co-injection of Cas9/sgRNA mRNA into zygotes. The LMNA-KO rabbits exhibited reduced locomotion activity with abnormal stiff walking posture and a shortened stature, all of them died within 22 days. In addition, cardiomyopathy, muscular dystrophy, bone and joint abnormalities, as well as lipodystrophy were observed in LMNA-KO rabbits. In conclusion, the novel rabbit LMNA-KO model, displayed typical features of histopathological defects that are observed in premature aging syndromes, and may be utilized as a valuable resource for understanding the pathophysiological mechanisms of premature aging syndromes and elucidating mysteries of the normal process of aging in humans.
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Affiliation(s)
- Tingting Sui
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Di Liu
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Tingjun Liu
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Jichao Deng
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Mao Chen
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Yuanyuan Xu
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Yuning Song
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Hongsheng Ouyang
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
| | - Liangxue Lai
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China.,2Key Laboratory of Regenerative Biology, and Guangdong Provincial Key Laboratory of Stem Cells and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong 510530, China
| | - Zhanjun Li
- 1Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University, Changchun 130062, China
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Glucotoxic and diabetic conditions induce caspase 6-mediated degradation of nuclear lamin A in human islets, rodent islets and INS-1 832/13 cells. Apoptosis 2015; 19:1691-701. [PMID: 25292013 DOI: 10.1007/s10495-014-1038-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Nuclear lamins form the lamina on the interior surface of the nuclear envelope, and regulate nuclear metabolic events, including DNA replication and organization of chromatin. The current study is aimed at understanding the role of executioner caspase 6 on lamin A integrity in islet β-cells under duress of glucotoxic (20 mM glucose; 24 h) and diabetic conditions. Under glucotoxic conditions, glucose-stimulated insulin secretion and metabolic cell viability were significantly attenuated in INS-1 832/13 cells. Further, exposure of normal human islets, rat islets and INS-1 832/13 cells to glucotoxic conditions leads to caspase 6 activation and lamin A degradation, which is also observed in islets from the Zucker diabetic fatty rat, a model for type 2 diabetes (T2D), and in islets from a human donor with T2D. Z-Val-Glu-Ile-Asp-fluoromethylketone, a specific inhibitor of caspase 6, markedly attenuated high glucose-induced caspase 6 activation and lamin A degradation, confirming that caspase 6 mediates lamin A degradation under high glucose exposure conditions. Moreover, Z-Asp-Glu-Val-Asp-fluoromethylketone, a known caspase 3 inhibitor, significantly inhibited high glucose-induced caspase 6 activation and lamin A degradation, suggesting that activation of caspase 3 might be upstream to caspase 6 activation in the islet β-cell under glucotoxic conditions. Lastly, we report expression of ZMPSTE24, a zinc metallopeptidase involved in the processing of prelamin A to mature lamin A, in INS-1 832/13 cells and human islets; was unaffected by high glucose. We conclude that caspases 3 and 6 could contribute to alterations in the integrity of nuclear lamins leading to metabolic dysregulation and failure of the islet β-cell.
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Zhang L, Shen H, Zhao Z, Bing Q, Hu J. Cardiac effects of the c.1583 C→G LMNA mutation in two families with Emery-Dreifuss muscular dystrophy. Mol Med Rep 2015; 12:5065-71. [PMID: 26165385 PMCID: PMC4581790 DOI: 10.3892/mmr.2015.4065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 06/05/2015] [Indexed: 11/24/2022] Open
Abstract
The present study aimed to examine and analyze cardiac involvement in two Emery-Dreifuss muscular dystrophy (EDMD) pedigrees caused by the c.1583 C→G mutation of the lamin A/C gene (LMNA). The clinical and genetic characteristics of members of two families with EDMD were evaluated by performing neurological examinations, skeletal muscle biopsies, cardiac evaluations, including electrocardiography, 24 h Holter, ultrasound cardiography and 99TcM-MIBI-gated myocardiac perfusion imaging, and genomic DNA sequencing. Family history investigations revealed an autosomal dominant transmission pattern of the disease in Family 1 and a sporadic case in Family 2. The three affected patients exhibited typical clinical features of EDMD, including joint contractures, muscle weakness and cardiac involvement. Muscle histopathological investigation revealed dystrophic features. In addition, each affected individual exhibited either cardiac arrhythmia, which was evident as sinus tachycardia, atrial flutter or complete atrioventricular inhibition. Cardiac imaging revealed dilated cardiomyopathy in two of the individuals, one of whom was presented with heart failure. The second patient presented with no significant abnormalities in cardiac structure or function. The three affected individuals exhibited a heterozygous missense mutation in the LMNA gene (c.1583 C→G), which caused a T528R amino acid change in the LMNA protein. In conclusion, the present study identified three patients with EDMD, exhibiting the same dominant LMNA mutation and presenting with a spectrum of severe cardiac abnormalities, including cardiac conduction system defects, cardiomyopathy and heart failure. As LMNA mutations have been associated with at least six clinical disorders, including EDMD, the results of the present study provide additional mutational and functional data, which may assist in further establishing LMNA mutational variation and disease pathogenesis.
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Affiliation(s)
- Li Zhang
- Department of Cardiovascular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China
| | - Hongrui Shen
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China
| | - Zhe Zhao
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China
| | - Qi Bing
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China
| | - Jing Hu
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, Hebei 050051, P.R. China
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Babbio F, Castiglioni I, Cassina C, Gariboldi MB, Pistore C, Magnani E, Badaracco G, Monti E, Bonapace IM. Knock-down of methyl CpG-binding protein 2 (MeCP2) causes alterations in cell proliferation and nuclear lamins expression in mammalian cells. BMC Cell Biol 2012; 13:19. [PMID: 22783988 PMCID: PMC3477090 DOI: 10.1186/1471-2121-13-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 07/03/2012] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND MeCP2 (CpG-binding protein 2) is a nuclear multifunctional protein involved in several cellular processes, like large-scale chromatin reorganization and architecture, and transcriptional regulation. In recent years, a non-neuronal role for MeCP2 has emerged in cell growth and proliferation. Mutations in the MeCP2 gene have been reported to determine growth disadvantages in cultured lymphocyte cells, and its functional ablation suppresses cell growth in glial cells and proliferation in mesenchymal stem cells and prostate cancer cells. MeCP2 interacts with lamin B receptor (LBR) and with Heterochromatin Protein 1 (HP1) at the nuclear envelope (NE), suggesting that it could be part of complexes involved in attracting heterochromatin at the nuclear periphery and in mediating gene silencing. The nuclear lamins, major components of the lamina, have a role in maintaining NE integrity, in orchestrating mitosis, in DNA replication and transcription, in regulation of mitosis and apoptosis and in providing anchoring sites for chromatin domains.In this work, we inferred that MeCP2 might have a role in nuclear envelope stability, thereby affecting the proliferation pattern of highly proliferating systems. RESULTS By performing knock-down (KD) of MeCP2 in normal murine (NIH-3 T3) and in human prostate transformed cells (PC-3 and LNCaP), we observed a strong proliferation decrease and a defect in the cell cycle progression, with accumulation of cells in S/G2M, without triggering a strong apoptotic and senescent phenotype. In these cells, KD of MeCP2 evidenced a considerable decrease of the levels of lamin A, lamin C, lamin B1 and LBR proteins. Moreover, by confocal analysis we confirmed the reduction of lamin A levels, but we also observed an alteration in the shape of the nuclear lamina and an irregular nuclear rim. CONCLUSIONS Our results that indicate reduced levels of NE components, are consistent with a hypothesis that the deficiency of MeCP2 might cause the lack of a key "bridge" function that links the peripheral heterochromatin to the NE, thereby causing an incorrect assembly of the NE itself, together with a decreased cell proliferation and viability.
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Affiliation(s)
- Federica Babbio
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Ilaria Castiglioni
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Chiara Cassina
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Marzia Bruna Gariboldi
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Christian Pistore
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Elena Magnani
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Gianfranco Badaracco
- Department of Biotechnologies and Life Sciences, Insubria University, via H. J. Dunant 3, Varese 21100, Italy
| | - Elena Monti
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
| | - Ian Marc Bonapace
- Department of Theoretical and Applied Sciences, Insubria University, via A. da Giussano 10, Busto Arsizio, 21052, Italy
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12
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Barboro P, Repaci E, D’Arrigo C, Balbi C. The role of nuclear matrix proteins binding to matrix attachment regions (Mars) in prostate cancer cell differentiation. PLoS One 2012; 7:e40617. [PMID: 22808207 PMCID: PMC3394767 DOI: 10.1371/journal.pone.0040617] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 06/11/2012] [Indexed: 11/19/2022] Open
Abstract
In tumor progression definite alterations in nuclear matrix (NM) protein composition as well as in chromatin structure occur. The NM interacts with chromatin via specialized DNA sequences called matrix attachment regions (MARs). In the present study, using a proteomic approach along with a two-dimensional Southwestern assay and confocal laser microscopy, we show that the differentiation of stabilized human prostate carcinoma cells is marked out by modifications both NM protein composition and bond between NM proteins and MARs. Well-differentiated androgen-responsive and slowly growing LNCaP cells are characterized by a less complex pattern and by a major number of proteins binding MAR sequences in comparison to 22Rv1 cells expressing androgen receptor but androgen-independent. Finally, in the poorly differentiated and strongly aggressive androgen-independent PC3 cells the complexity of NM pattern further increases and a minor number of proteins bind the MARs. Furthermore, in this cell line with respect to LNCaP cells, these changes are synchronous with modifications in both the nuclear distribution of the MAR sequences and in the average loop dimensions that significantly increase. Although the expression of many NM proteins changes during dedifferentiation, only a very limited group of MAR-binding proteins seem to play a key role in this process. Variations in the expression of poly (ADP-ribose) polymerase (PARP) and special AT-rich sequence-binding protein-1 (SATB1) along with an increase in the phosphorylation of lamin B represent changes that might trigger passage towards a more aggressive phenotype. These results suggest that elucidating the MAR-binding proteins that are involved in the differentiation of prostate cancer cells could be an important tool to improve our understanding of this carcinogenesis process, and they could also be novel targets for prostate cancer therapy.
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Affiliation(s)
- Paola Barboro
- IRCCS Azienda Ospedaliera Universitaria San Martino IST-Istituto Nazionale per la Ricerca sul Cancro, Department of Diagnostic Technologies, Genoa, Italy
| | - Erica Repaci
- IRCCS Azienda Ospedaliera Universitaria San Martino IST-Istituto Nazionale per la Ricerca sul Cancro, Department of Diagnostic Technologies, Genoa, Italy
| | - Cristina D’Arrigo
- C.N.R., Istituto per lo Studio delle Macromolecole, ISMAC, Sezione di Genova, Genoa, Italy
| | - Cecilia Balbi
- IRCCS Azienda Ospedaliera Universitaria San Martino IST-Istituto Nazionale per la Ricerca sul Cancro, Department of Diagnostic Technologies, Genoa, Italy
- * E-mail:
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13
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Shimi T, Butin-Israeli V, Adam SA, Hamanaka RB, Goldman AE, Lucas CA, Shumaker DK, Kosak ST, Chandel NS, Goldman RD. The role of nuclear lamin B1 in cell proliferation and senescence. Genes Dev 2011; 25:2579-93. [PMID: 22155925 DOI: 10.1101/gad.179515.111] [Citation(s) in RCA: 376] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nuclear lamin B1 (LB1) is a major structural component of the nucleus that appears to be involved in the regulation of many nuclear functions. The results of this study demonstrate that LB1 expression in WI-38 cells decreases during cellular senescence. Premature senescence induced by oncogenic Ras also decreases LB1 expression through a retinoblastoma protein (pRb)-dependent mechanism. Silencing the expression of LB1 slows cell proliferation and induces premature senescence in WI-38 cells. The effects of LB1 silencing on proliferation require the activation of p53, but not pRb. However, the induction of premature senescence requires both p53 and pRb. The proliferation defects induced by silencing LB1 are accompanied by a p53-dependent reduction in mitochondrial reactive oxygen species (ROS), which can be rescued by growth under hypoxic conditions. In contrast to the effects of LB1 silencing, overexpression of LB1 increases the proliferation rate and delays the onset of senescence of WI-38 cells. This overexpression eventually leads to cell cycle arrest at the G1/S boundary. These results demonstrate the importance of LB1 in regulating the proliferation and senescence of human diploid cells through a ROS signaling pathway.
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Affiliation(s)
- Takeshi Shimi
- Department of Cell and Molecular Biology, Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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14
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Dahl KN, Kalinowski A, Pekkan K. Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics. Microcirculation 2010; 17:179-91. [PMID: 20374482 DOI: 10.1111/j.1549-8719.2009.00016.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson-Gilford progeria syndrome, is reviewed specifically as the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation as visualization in situ is difficult. This integrated approach to study--including medicine, molecular and cell biology, biophysics and engineering--provides a unique understanding of multi-scale interactions in the microcirculation.
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Affiliation(s)
- Kris Noel Dahl
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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15
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Kapinos LE, Schumacher J, Mücke N, Machaidze G, Burkhard P, Aebi U, Strelkov SV, Herrmann H. Characterization of the head-to-tail overlap complexes formed by human lamin A, B1 and B2 "half-minilamin" dimers. J Mol Biol 2010; 396:719-31. [PMID: 20004208 DOI: 10.1016/j.jmb.2009.12.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/17/2022]
Abstract
Half-minilamins, representing amino- and carboxy-terminal fragments of human lamins A, B1 and B2 with a truncated central rod domain, were investigated for their ability to form distinct head-to-tail-type dimer complexes. This mode of interaction represents an essential step in the longitudinal assembly reaction exhibited by full-length lamin dimers. As determined by analytical ultracentrifugation, the amino-terminal fragments were soluble under low ionic strength conditions sedimenting with distinct profiles and s-values (1.6-1.8 S) indicating the formation of coiled-coil dimers. The smaller carboxy-terminal fragments were, except for lamin B2, largely insoluble under these conditions. However, after equimolar amounts of homotypic amino- and carboxy-terminal lamin fragments had been mixed in 4 M urea, upon subsequent renaturation the carboxy-terminal fragments were completely rescued from precipitation and distinct soluble complexes with higher s-values (2.3-2.7 S) were obtained. From this behavior, we conclude that the amino- and carboxy-terminal coiled-coil dimers interact to form distinct oligomers (i.e. tetramers). Furthermore, a corresponding interaction occurred also between heterotypic pairs of A- and B-type lamin fragments. Hence, A-type lamin dimers may interact with B-type lamin dimers head-to-tail to yield linear polymers. These findings indicate that a lamin dimer principally has the freedom for a "combinatorial" head-to-tail association with all types of lamins, a property that might be of significant importance for the assembly of the nuclear lamina. Furthermore, we suggest that the head-to-tail interaction of the rod end domains represents a principal step in the assembly of cytoplasmic intermediate filament proteins too.
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Affiliation(s)
- Larisa E Kapinos
- M.E. Müller Institute for Structural Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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16
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17
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A progeria mutation reveals functions for lamin A in nuclear assembly, architecture, and chromosome organization. Proc Natl Acad Sci U S A 2009; 106:20788-93. [PMID: 19926845 DOI: 10.1073/pnas.0911895106] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Numerous mutations in the human A-type lamin gene (LMNA) cause the premature aging disease, progeria. Some of these are located in the alpha-helical central rod domain required for the polymerization of the nuclear lamins into higher order structures. Patient cells with a mutation in this domain, 433G>A (E145K) show severely lobulated nuclei, a separation of the A- and B-type lamins, alterations in pericentric heterochromatin, abnormally clustered centromeres, and mislocalized telomeres. The induction of lobulations and the clustering of centromeres originate during postmitotic nuclear assembly in daughter cells and this early G1 configuration of chromosomes is retained throughout interphase. In vitro analyses of E145K-lamin A show severe defects in the assembly of protofilaments into higher order lamin structures. The results show that this central rod domain mutation affects nuclear architecture in a fashion distinctly different from the changes found in the most common form of progeria caused by the expression of LADelta50/progerin. The study also emphasizes the importance of lamins in nuclear assembly and chromatin organization.
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18
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Wojtanik KM, Edgemon K, Viswanadha S, Lindsey B, Haluzik M, Chen W, Poy G, Reitman M, Londos C. The role of LMNA in adipose: a novel mouse model of lipodystrophy based on the Dunnigan-type familial partial lipodystrophy mutation. J Lipid Res 2009; 50:1068-79. [PMID: 19201734 DOI: 10.1194/jlr.m800491-jlr200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the role of LMNA in adipose tissue by developing a novel mouse model of lipodystrophy. Transgenic mice were generated that express the LMNA mutation that causes familial partial lipodystrophy of the Dunnigan type (FPLD2). The phenotype observed in FPLD-transgenic mice resembles many of the features of human FPLD2, including lack of fat accumulation, insulin resistance, and enlarged, fatty liver. Similar to the human disease, FPLD-transgenic mice appear to develop normally, but after several weeks they are unable to accumulate fat to the same extent as their wild-type littermates. One poorly understood aspect of lipodystrophies is the mechanism of fat loss. To this end, we have examined the effects of the FPLD2 mutation on fat cell function. Contrary to the current literature, which suggests FPLD2 results in a loss of fat, we found that the key mechanism contributing to the lack of fat accumulation involves not a loss, but an apparent inability of the adipose tissue to renew itself. Specifically, preadipocytes are unable to differentiate into mature and fully functional adipocytes. These findings provide insights not only for the treatment of lipodystrophies, but also for the study of adipogenesis, obesity, and insulin resistance.
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Affiliation(s)
- Kari M Wojtanik
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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19
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Shimi T, Pfleghaar K, Kojima SI, Pack CG, Solovei I, Goldman AE, Adam SA, Shumaker DK, Kinjo M, Cremer T, Goldman RD. The A- and B-type nuclear lamin networks: microdomains involved in chromatin organization and transcription. Genes Dev 2009; 22:3409-21. [PMID: 19141474 DOI: 10.1101/gad.1735208] [Citation(s) in RCA: 374] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The nuclear lamins function in the regulation of replication, transcription, and epigenetic modifications of chromatin. However, the mechanisms responsible for these lamin functions are poorly understood. We demonstrate that A- and B-type lamins form separate, but interacting, stable meshworks in the lamina and have different mobilities in the nucleoplasm as determined by fluorescence correlation spectroscopy (FCS). Silencing lamin B1 (LB1) expression dramatically increases the lamina meshwork size and the mobility of nucleoplasmic lamin A (LA). The changes in lamina mesh size are coupled to the formation of LA/C-rich nuclear envelope blebs deficient in LB2. Comparative genomic hybridization (CGH) analyses of microdissected blebs, fluorescence in situ hybridization (FISH), and immunofluorescence localization of modified histones demonstrate that gene-rich euchromatin associates with the LA/C blebs. Enrichment of hyperphosphorylated RNA polymerase II (Pol II) and histone marks for active transcription suggest that blebs are transcriptionally active. However, in vivo labeling of RNA indicates that transcription is decreased, suggesting that the LA/C-rich microenvironment induces promoter proximal stalling of Pol II. We propose that different lamins are organized into separate, but interacting, microdomains and that LB1 is essential for their organization. Our evidence suggests that the organization and regulation of chromatin are influenced by interconnections between these lamin microdomains.
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Affiliation(s)
- Takeshi Shimi
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA
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20
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Epstein-Barr virus BGLF4 kinase induces disassembly of the nuclear lamina to facilitate virion production. J Virol 2008; 82:11913-26. [PMID: 18815303 DOI: 10.1128/jvi.01100-08] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
DNA viruses adopt various strategies to modulate the cellular environment for efficient genome replication and virion production. Previously, we demonstrated that the BGLF4 kinase of Epstein-Barr virus (EBV) induces premature chromosome condensation through the activation of condensin and topoisomerase IIalpha (C. P. Lee, J. Y. Chen, J. T. Wang, K. Kimura, A. Takemoto, C. C. Lu, and M. R. Chen, J. Virol. 81:5166-5180, 2007). In this study, we show that BGLF4 interacts with lamin A/C and phosphorylates lamin A protein in vitro. Using a green fluorescent protein (GFP)-lamin A system, we found that Ser-22, Ser-390, and Ser-392 of lamin A are important for the BGLF4-induced disassembly of the nuclear lamina and the EBV reactivation-mediated redistribution of nuclear lamin. Virion production and protein levels of two EBV primary envelope proteins, BFRF1 and BFLF2, were reduced significantly by the expression of GFP-lamin A(5A), which has five Ser residues replaced by Ala at amino acids 22, 390, 392, 652, and 657 of lamin A. Our data indicate that BGLF4 kinase phosphorylates lamin A/C to promote the reorganization of the nuclear lamina, which then may facilitate the interaction of BFRF1 and BFLF2s and subsequent virion maturation. UL kinases of alpha- and betaherpesviruses also induce the disassembly of the nuclear lamina through similar sites on lamin A/C, suggesting a conserved mechanism for the nuclear egress of herpesviruses.
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21
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Haque F, Lloyd DJ, Smallwood DT, Dent CL, Shanahan CM, Fry AM, Trembath RC, Shackleton S. SUN1 interacts with nuclear lamin A and cytoplasmic nesprins to provide a physical connection between the nuclear lamina and the cytoskeleton. Mol Cell Biol 2006; 26:3738-51. [PMID: 16648470 PMCID: PMC1488999 DOI: 10.1128/mcb.26.10.3738-3751.2006] [Citation(s) in RCA: 386] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear migration and positioning within cells are critical for many developmental processes and are governed by the cytoskeletal network. Although mechanisms of nuclear-cytoskeletal attachment are unclear, growing evidence links a novel family of nuclear envelope (NE) proteins that share a conserved C-terminal SUN (Sad1/UNC-84 homology) domain. Analysis of Caenorhabditis elegans mutants has implicated UNC-84 in actin-mediated nuclear positioning by regulating NE anchoring of a giant actin-binding protein, ANC-1. Here, we report the identification of SUN1 as a lamin A-binding protein in a yeast two-hybrid screen. We demonstrate that SUN1 is an integral membrane protein located at the inner nuclear membrane. While the N-terminal domain of SUN1 is responsible for detergent-resistant association with the nuclear lamina and lamin A binding, lamin A/C expression is not required for SUN1 NE localization. Furthermore, SUN1 does not interact with type B lamins, suggesting that NE localization is ensured by binding to an additional nuclear component(s), most likely chromatin. Importantly, we find that the luminal C-terminal domain of SUN1 interacts with the mammalian ANC-1 homologs nesprins 1 and 2 via their conserved KASH domain. Our data provide evidence of a physical nuclear-cytoskeletal connection that is likely to be a key mechanism in nuclear-cytoplasmic communication and regulation of nuclear position.
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Affiliation(s)
- Farhana Haque
- Department of Genetics, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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22
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Ali F, Paré PD, Seow CY. Models of contractile units and their assembly in smooth muscle. Can J Physiol Pharmacol 2006; 83:825-31. [PMID: 16333353 DOI: 10.1139/y05-052] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is believed that the contractile filaments in smooth muscle are organized into arrays of contractile units (similar to the sarcomeric structure in striated muscle), and that such an organization is crucial for transforming the mechanical activities of actomyosin interaction into cell shortening and force generation. Details of the filament organization, however, are still poorly understood. Several models of contractile filament architecture are discussed here. To account for the linear relationship observed between the force generated by a smooth muscle and the muscle length at the plateau of an isotonic contraction, a model of contractile unit is proposed. The model consists of 2 dense bodies with actin (thin) filaments attached, and a myosin (thick) filament lying between the parallel thin filaments. In addition, the thick filament is assumed to span the whole contractile unit length, from dense body to dense body, so that when the contractile unit shortens, the amount of overlap between the thick and thin filaments (i.e., the distance between the dense bodies) decreases in exact proportion to the amount of shortening. Assembly of the contractile units into functional contractile apparatus is assumed to involve a group of cells that form a mechanical syncytium. The contractile apparatus is assumed malleable in that the number of contractile units in series and in parallel can be altered to accommodate strains on the muscle and to maintain the muscle's optimal mechanical function.
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Affiliation(s)
- Farah Ali
- Department of Experimental Medicine, University of British Columbia, Vancouver, Canada
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23
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Shimojo M, Hersh LB. Characterization of the REST/NRSF-interacting LIM domain protein (RILP): localization and interaction with REST/NRSF. J Neurochem 2006; 96:1130-8. [PMID: 16417580 DOI: 10.1111/j.1471-4159.2005.03608.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We previously identified a nuclear envelope protein repressor element-1 silencing transcription factor (REST)/neuron-restrictive silencer factor (NRSF)-interacting Lin-11, Isl-1 and Mec-3 (LIM) domain protein (RILP) that we proposed functions in the nuclear translocation of the transcriptional repressor REST/NRSF. In this study we assessed the functionality of the prenylation motif, protein kinase A (PKA) phosphorylation sites and nuclear localization sequences (NLSs) of RILP. [(3)H]-mevalonolactone labeled endogenous RILP, showing that RILP is indeed prenylated, while phosphorylation analysis showed that the two PKA sites are phosphorylated. Blocking RILP prenylation, mutating the NLSs or mutating the PKA phosphorylation sites caused RILP to mislocalize to the cytosol. Concurrent with this mislocalization of RILP, REST/NRSF and REST4, which are normally found in the nucleus, co-localized in the cytosol with the RILP mutants. This provides additional evidence that RILP interacts with REST/NRSF and REST4 in vivo, and is involved in the nuclear localization of REST/NRSF and REST4. Reporter gene analysis using the promoter region of the human cholinergic gene locus revealed that these RILP mutants prevented repression of the reporter gene. By trapping REST/NRSF in the cytosol, the RILP mutants prevented translocation to the nucleus where REST/NRSF binds to an RE-1/NRSE element to repress gene transcription. These results show that RILP is required for REST/NRSF nuclear targeting and function.
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Affiliation(s)
- Masahito Shimojo
- Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky 40536-0298, USA.
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24
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Guglieri M, Magri F, Comi GP. Molecular etiopathogenesis of limb girdle muscular and congenital muscular dystrophies: Boundaries and contiguities. Clin Chim Acta 2005; 361:54-79. [PMID: 16002060 DOI: 10.1016/j.cccn.2005.05.020] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 05/11/2005] [Accepted: 05/12/2005] [Indexed: 10/25/2022]
Abstract
The muscular dystrophies are a heterogeneous group of inherited disorders characterized by progressive muscle wasting and weakness. These disorders present a large clinical variability regarding age of onset, patterns of skeletal muscle involvement, heart damage, rate of progression and mode of inheritance. Difficulties in classification are often caused by the relatively common sporadic occurrence of autosomal recessive forms as well as by intrafamilial clinical variability. Furthermore recent discoveries, particularly regarding the proteins linking the sarcolemma to components of the extracellular matrix, have restricted the gap existing between limb girdle (LGMD) and congenital muscular dystrophies (CMD). Therefore a renewed definition of boundaries between these two groups is required. Molecular genetic studies have demonstrated different causative mutations in the genes encoding a disparate collection of proteins involved in all aspects of muscle cell biology. These novel skeletal muscle genes encode highly diverse proteins with different localization within or at the surface of the skeletal muscle fibre, such as the sarcolemmal muscle membrane (dystrophin, sarcoglycans, dysferlin, caveolin-3), the extracellular matrix (alpha2 laminin, collagen VI), the sarcomere (telethonin, myotilin, titin, nebulin and ZASP), the muscle cytosol (calpain-3, TRIM32), the nucleus (emerin, lamin A/C) and the glycosilation pathway enzymes (fukutin and fukutin related proteins). The accumulating knowledge about the role of these different proteins in muscle pathology has led to a profound change in the original phenotype-based classification and shed new light on the molecular pathogenesis of these disorders.
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Affiliation(s)
- Michela Guglieri
- Centro Dino Ferrari, Dipartimento di Scienze Neurologiche Università degli Studi di Milano, I.R.C.C.S. Ospedale Maggiore Policlinico, Milano, Italy
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25
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Dahl KN, Engler AJ, Pajerowski JD, Discher DE. Power-law rheology of isolated nuclei with deformation mapping of nuclear substructures. Biophys J 2005; 89:2855-64. [PMID: 16055543 PMCID: PMC1366783 DOI: 10.1529/biophysj.105.062554] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 07/19/2005] [Indexed: 01/21/2023] Open
Abstract
Force-induced changes in genome expression as well as remodeling of nuclear architecture in development and disease motivate a deeper understanding of nuclear mechanics. Chromatin and green fluorescent protein-lamin B dynamics were visualized in a micropipette aspiration of isolated nuclei, and both were shown to contribute to viscoelastic properties of the somatic cell nucleus. Reversible swelling by almost 200% in volume, with changes in salt, demonstrates the resilience and large dilational capacity of the nuclear envelope, nucleoli, and chromatin. Swelling also proves an effective way to separate the mechanical contributions of nuclear elements. In unswollen nuclei, chromatin is a primary force-bearing element, whereas swollen nuclei are an order of magnitude softer, with the lamina sustaining much of the load. In both cases, nuclear deformability increases with time, scaling as a power law-thus lacking any characteristic timescale-when nuclei are either aspirated or indented by atomic force microscopy. The nucleus is stiff and resists distortion at short times, but it softens and deforms more readily at longer times. Such results indicate an essentially infinite spectrum of timescales for structural reorganization, with implications for regulating genome expression kinetics.
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26
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McPhillips MG, Ozato K, McBride AA. Interaction of bovine papillomavirus E2 protein with Brd4 stabilizes its association with chromatin. J Virol 2005; 79:8920-32. [PMID: 15994786 PMCID: PMC1168793 DOI: 10.1128/jvi.79.14.8920-8932.2005] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The bovine papillomavirus E2 protein maintains and segregates the viral extrachromosomal genomes by tethering them to cellular mitotic chromosomes. E2 interacts with a cellular bromodomain protein, Brd4, to mediate the segregation of viral genomes into daughter cells. Brd4 binds acetylated histones and has been observed to diffusely coat mitotic chromosomes in several cell types. In this study, we show that in mitotic C127 cells, Brd4 diffusely coated the condensed chromosomes. However, in the presence of the E2 protein, E2 and Brd4 colocalized in punctate dots that were randomly distributed over the chromosomes. A similar pattern of E2 and Brd4 colocalization on mitotic chromosomes was observed in CV-1 cells, whereas only a faint chromosomal coating of Brd4 was detected in the absence of the E2 protein. Therefore, the viral E2 protein relocalizes and/or stabilizes the association of Brd4 with chromosomes in mitotic cells. The colocalization of E2 and Brd4 was also observed in interphase cells, indicating that this protein-protein interaction persists throughout the cell cycle. The interaction of E2 with Brd4 greatly stabilized the association of Brd4 with interphase chromatin. In both mitotic and interphase cells, this stabilization required a transcriptionally competent transactivation domain, but not the DNA binding function of the E2 protein. Thus, the E2 protein modulates the chromatin association of Brd4 during both interphase and mitosis. This study demonstrates that the segregation of papillomavirus genomes is not simply due to the passive hitchhiking of the E2/genome complex with a convenient cellular chromosomal protein.
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Affiliation(s)
- Maria G McPhillips
- Laboratory of Viral Diseases, NIAID, NIH, Building 4, Room 137, 4 Center Dr., MSC 0455, Bethesda, MD 20892-0455, USA
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27
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Senda T, Iizuka-Kogo A, Shimomura A. Visualization of the nuclear lamina in mouse anterior pituitary cells and immunocytochemical detection of lamin A/C by quick-freeze freeze-substitution electron microscopy. J Histochem Cytochem 2005; 53:497-507. [PMID: 15805424 DOI: 10.1369/jhc.4a6478.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the nuclear lamina in the quickly frozen anterior pituitary cells by electron microscopic techniques combined with freeze substitution, deep etching, and immunocytochemistry and compared it with that in the chemically fixed cells. By quick-freeze freeze-substitution electron microscopy, an electron-lucent layer, as thick as 20 nm, was revealed just inside the inner nuclear membrane, whereas in the conventionally glutaraldehyde-fixed cells the layer was not seen. By quick-freeze deep-etch electron microscopy, we could not distinguish definitively the layer corresponding to the nuclear lamina in either fresh unfixed or glutaraldehyde-fixed cells. Immunofluorescence microscopy showed that lamin A/C in the nucleus was detected in the acetone-fixed cells and briefly in paraformaldehyde-fixed cells but not in the cells with prolonged paraformaldehyde fixation. Nuclear localization of lamin A/C was revealed by immunogold electron microscopy also in the quickly frozen and freeze-substituted cells, but not in the paraformaldehyde-fixed cells. Lamin A/C was localized mainly in the peripheral nucleoplasm within 60 nm from the inner nuclear membrane, which corresponded to the nuclear lamina. These results suggest that the nuclear lamina can be preserved both ultrastructurally and immunocytochemically by quick-freezing fixation, rather than by conventional chemical fixation.
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Affiliation(s)
- Takao Senda
- Department of Anatomy I, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan.
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Veluthakal R, Amin R, Kowluru A. Interleukin-1β induces posttranslational carboxymethylation and alterations in subnuclear distribution of lamin B in insulin-secreting RINm5F cells. Am J Physiol Cell Physiol 2004; 287:C1152-62. [PMID: 15201138 DOI: 10.1152/ajpcell.00083.2004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We examined the effects of interleukin-1β (IL-1β) treatment on the distribution and degradation of lamin B in the nuclear fraction from insulin-secreting RINm5F cells. Western blot analysis indicated that IL-1β treatment caused significant alterations in the redistribution of lamin B, specifically between the Triton X-100-soluble (membrane) and -insoluble (matrix) fractions of the nucleus. IL-1β treatment also increased the lamin carboxymethyltransferase activity and the relative abundance of the carboxymethylated lamin in the nuclear fraction. A significant increase in the relative abundance of lamin B degradation products was also observed in the nuclear fraction from the IL-1β-treated cells. These findings are compatible with a measurable increase in the lamin-degrading caspase-6 activity in IL-1β-treated cells. Confocal microscopic observation of IL-1β-treated cells suggested a significant dissociation of lamin B from the nuclear lamina and its subsequent association with the DNA-rich elements within the nucleus. NG-monomethyl-l-arginine, a known inhibitor of inducible nitric oxide synthetase (iNOS), markedly inhibited IL-1β-induced iNOS gene expression, NO release, caspase-3 and caspase-6 activation, lamin B degradation, and loss of metabolic cell viability, indicating that the observed IL-1β-induced effects on nuclear lamin B involve the intermediacy of NO. Together, our data support the hypothesis that IL-1β treatment results in significant increase in the carboxymethylation of lamin B, which would place lamin B in a strategic location for its degradation mediated by caspases. This could possibly lead to dissolution of the nuclear envelope, culminating in the demise of the effete β-cell.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, 259 Mack Ave., Detroit, MI 48201, USA
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29
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Voronin AP, Lobov IB, Gilson E, Podgornaya OI. A telomere-binding protein (TRF2/MTBP) from mouse nuclear matrix with motives of an intermediate filament-type rod domain. ACTA ACUST UNITED AC 2004; 6:205-18. [PMID: 14987434 DOI: 10.1089/109454503322733054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In previous work, we identified a telomeric DNA-binding protein (termed telomere-membrane binding protein, MTBP) in the envelope of the frog oocyte nucleus and raised antibodies against it. Here we present immunological evidence which suggests strongly that MTBP is identical with the vertebrate telomeric DNA-binding protein TRF2 (telomere-repeat factor 2). MTBP/TRF2 possesses motif which resembles rod domain characteristic of intermediate filament (IF) proteins as shown by immunological cross-reactivity with characteristic antibodies, as well as amino acid sequence homology. Anti-MTBP antibodies recognised a protein of the same M, as TRF2 in extracts of mouse nuclei and nuclear matrix as shown by ion-exchange chromatography, gel shift assays, and Western blots. This mouse MTBP analogue forms more stable complexes with the vertebrate telomeric DNA fragment (T(2)AG(3))(135) than with the corresponding fragment from Tetrahymena (T(2)G(4))(130). Proteins in each of these complexes are recognised by anti-MTBP antibody. In situ hybridization with the vertebrate telomeric DNA sequence (T(2)AG(3))(135) and immunofluorescence with anti-MTBP antibody had shown earlier that these are co-localised in the nucleus of mouse cells, and here MTBP is shown to be associated with the residual membrane of hepatocyte nuclei using Western blotting and immunofluorescence. Some immunofluorescence signal from MTBP is localized at chromosome extremities on metaphase plates from mouse cell culture, but the main signal is seen in patches scattered around the chromosomes which were identified as remnants of the nuclear envelope by double labelling with antibodies against lamin B. These observations suggest that MTBP/TRF2 is a good candidate for the attachment of telomeres to the nuclear envelope in somatic cells.
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Affiliation(s)
- Alexey P Voronin
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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30
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Dewji NN, Valdez D, Singer SJ. The presenilins turned inside out: implications for their structures and functions. Proc Natl Acad Sci U S A 2004; 101:1057-62. [PMID: 14732691 PMCID: PMC327150 DOI: 10.1073/pnas.0307290101] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The presenilin (PS) proteins are polytopic integral membrane proteins that are critically involved in the development of Alzheimer's disease. The topography of the PS molecule in the endoplasmic reticulum membrane is widely accepted as exhibiting eight-hydrophobic-transmembrane (8-TM) helices. We have previously provided evidence, however, that the intact PS molecule is also present in the cell surface where it exhibits exclusively a 7-TM topography, which differs in significant structural features from the 8-TM model. This evidence, however, has been disparaged and generally rejected by researchers in Alzheimer's disease. The 7-TM model is definitively demonstrated in the present study for PS-1 at the surfaces of PS-1-transfected cells and for endogenous PS-1 at the surfaces of untransfected cells, by immunofluorescence studies using mAbs. These studies force substantial revision of current views of the structural and functional properties of the PS proteins.
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Affiliation(s)
- Nazneen N Dewji
- Departments of Medicine and Biology, University of California at San Diego, La Jolla, CA 92093, USA.
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31
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Shimojo M, Hersh LB. REST/NRSF-interacting LIM domain protein, a putative nuclear translocation receptor. Mol Cell Biol 2004; 23:9025-31. [PMID: 14645515 PMCID: PMC309669 DOI: 10.1128/mcb.23.24.9025-9031.2003] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transcriptional repressor REST/NRSF (RE-1 silencing transcription factor/neuron-restrictive silencer factor) and the transcriptional regulator REST4 share an N-terminal zinc finger domain structure involved in nuclear targeting. Using this domain as bait in a yeast two-hybrid screen, a novel protein that contains three LIM domains, putative nuclear localization sequences, protein kinase A phosphorylation sites, and a CAAX prenylation motif was isolated. This protein, which is localized around the nucleus, is involved in determining the nuclear localization of REST4 and REST/NRSF. We propose the name RILP, for REST/NRSF-interacting LIM domain protein, to label this novel protein. RILP appears to serve as a nuclear receptor for REST/NRSF, REST4, and possibly other transcription factors.
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Affiliation(s)
- Masahito Shimojo
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Chandler Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA.
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32
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Fischer AH, Taysavang P, Jhiang SM. Nuclear envelope irregularity is induced by RET/PTC during interphase. THE AMERICAN JOURNAL OF PATHOLOGY 2003; 163:1091-100. [PMID: 12937150 PMCID: PMC1868259 DOI: 10.1016/s0002-9440(10)63468-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nuclear envelope (NE) irregularity is an important diagnostic feature of cancer, and its molecular basis is not understood. One possible cause is abnormal postmitotic NE re-assembly, such that a rounded contour is never achieved before the next mitosis. Alternatively, dynamic forces could deform the NE during interphase following an otherwise normal postmitotic NE re-assembly. To distinguish these possibilities, normal human thyroid epithelial cells were microinjected with the papillary thyroid carcinoma oncogene (RET/PTC1 short isoform, known to induce NE irregularity), an attenuated version of RET/PTC1 lacking the leucine zipper dimerization domain (RET/PTC1 Deltazip), H (V-12) RAS, and labeled dextran. Cells were fixed at 6 or 18 to 24 hours, stained for lamins and the products of microinjected plasmids, and scored blindly using previously defined criteria for NE irregularity. 6.5% of non-injected thyrocytes showed NE irregularity. Neither dextran nor RAS microinjections increased NE irregularity. In contrast, RET/PTC1 microinjection induced NE irregularity in 27% of cells at 6 hours and 37% of cells at 18 to 24 hours. RET/PTC1 Deltazip induced significantly less irregularity. Since irregularity develops quickly, and since no mitoses and only rare possible postmitotic cells were scored, postmitotic NE re-assembly does not appear necessary for RET/PTC signaling to induce an irregular NE contour.
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Affiliation(s)
- Andrew H Fischer
- Department of Pathology, Emory University Hospital, Atlanta, Georgia, USA.
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Fidziańska A, Hausmanowa-Petrusewicz I. Architectural abnormalities in muscle nuclei. Ultrastructural differences between X-linked and autosomal dominant forms of EDMD. J Neurol Sci 2003; 210:47-51. [PMID: 12736087 DOI: 10.1016/s0022-510x(03)00012-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES The aim of our study was to compare the ultrastructure of myonuclei in both forms of Emery-Dreifuss dystrophy (EDMD)-X-linked and dominantly autosomally transmitted. The muscle biopsies were taken from rectus femoris in four X-linked EDMD cases and three ADEDMD cases. METHODS The biopsies were evaluated using immunocytochemical staining to establish emerin or A/C lamins deficiency. The muscle ultrastructure, especially that of nuclei, was analysed to find out whether there are differences between the two forms of EDMD. RESULTS In both forms of EDMD, there was an aberrant nuclear architecture. In the X-linked form, the breakdown of fragile nuclear membrane and presence of nucleoplasm extrusion were a distinct feature. In the AD from, there was chromatin reorganization and loss of nucleoplasm volume.
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Affiliation(s)
- Anna Fidziańska
- Neuromuscular Unit, Medical Research Centre, Polish Academy of Sciences, 1a, Banacha Str. bld. D, 02-097 Warsaw, Poland
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Tilli CMLJ, Ramaekers FCS, Broers JLV, Hutchison CJ, Neumann HAM. Lamin expression in normal human skin, actinic keratosis, squamous cell carcinoma and basal cell carcinoma. Br J Dermatol 2003; 148:102-9. [PMID: 12534602 DOI: 10.1046/j.1365-2133.2003.05026.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Aberrant expression patterns of nuclear lamins have been described in various types of cancer depending on the subtype of cancer, its aggressiveness, proliferative capacity and degree of differentiation. In general, the expression of A-type lamins (lamins A and C) has been correlated with a non-proliferating, differentiated state of cells and tissues. OBJECTIVES To establish and compare the expression patterns of lamins in normal human skin, actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). METHODS Expression patterns of the individual lamin subtypes were studied immunohistochemically. The proliferation capacity of the tumour cells was detected using a specific antibody to Ki-67, and was related to the A-type lamin expression patterns. RESULTS In normal skin, lamin A was expressed in the suprabasal cell compartment of the epidermis, whereas the basal cells were mostly unstained. BCCs and SCCs stained positive in most cells, while the epidermis overlying BCC and SCC and the epidermis in AK stained homogeneously and strongly in the basal cells in addition to the suprabasal cells. Lamin C was expressed in some basal cells of normal epidermis while the suprabasal cells stained strongly positive. Both BCCs and SCCs stained strongly positive for lamin C, with the difference that in BCC the staining was predominantly present in nucleolar structures with occasional staining of the nuclear envelope. The epidermis overlying SCC showed strong positivity in the lamina of virtually all cells. The expression of lamin C in the basal cells of AK resembled the expression pattern seen in the epidermis overlying BCC, i.e. a nucleolar staining next to nuclear envelope staining. Lamin B1 and B2 were found in virtually all cells in normal epidermis, AK, BCC, SCC and the epidermis overlying cancer. The percentage of Ki-67-expressing cells was highest in BCC (45%), and gradually decreased via epidermis overlying BCC, AK, SCC, and epidermis overlying SCC, to normal skin (11%). Simultaneous expression of A-type lamins and Ki-67 occurred in approximately 50% of the proliferating (Ki-67 positive) cells in BCC and SCC. CONCLUSIONS Significant changes occur in the expression patterns of A-type lamins in both premalignant and malignant lesions of the skin. The profound overlap of lamin A and Ki-67 staining patterns indicates that the proliferating tumour cells may obtain a certain degree of differentiation. Finally, lamin A expression in the basal cell layer of the apparently normal epidermis overlying BCC may suggest its involvement in the primary process.
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Affiliation(s)
- C M L J Tilli
- Department of Dermatology, University Hospital Maastricht, PO Box 5800, the Netherlands.
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35
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Oguchi M, Sagara J, Matsumoto K, Saida T, Taniguchi S. Expression of lamins depends on epidermal differentiation and transformation. Br J Dermatol 2002; 147:853-8. [PMID: 12410693 DOI: 10.1046/j.1365-2133.2002.04948.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND It has been suggested that A- and B-type lamins, proteins of the nuclear lamina, play important roles in the morphogenesis of the nucleus and cellular differentiation. OBJECTIVE To investigate the expression of these nuclear proteins in normal skin and some keratinocytic tumours of the skin. METHODS We examined by means of immunohistochemistry the expression of lamins in normal skin and some keratinocytic tumours of the skin, such as squamous cell carcinoma (SCC), basal cell carcinoma (BCC), Bowen's disease, solar keratosis, keratoacanthoma and seborrhoeic keratosis. RESULTS In normal skin, A-type lamin was expressed in all epidermal cells, but the expression level of B-type lamins diminished from basal cells to granular cells. In keratinocytic tumours, the expression of A-type lamin was reduced, especially in BCCs, Bowen's disease and poorly differentiated SCCs. B-type lamins were reduced and exhibited heterogeneous expression patterns in most well-differentiated SCCs and keratoacanthomas. Antibodies against B-type lamins stained only peripheral cells of the lobules in keratoacanthomas, while no regular staining patterns were seen in well-differentiated SCCs. CONCLUSIONS Lamin expression depends on the differentiation and transformation of the human skin. This finding should be useful for the diagnosis of keratinocytic tumours.
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Affiliation(s)
- M Oguchi
- Departments of Dermatology and Molecular Oncology and Angiology, Research Center on Aging and Adaptation, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Japan
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36
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Spann TP, Goldman AE, Wang C, Huang S, Goldman RD. Alteration of nuclear lamin organization inhibits RNA polymerase II-dependent transcription. J Cell Biol 2002; 156:603-8. [PMID: 11854306 PMCID: PMC2174089 DOI: 10.1083/jcb.200112047] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Regulation of gene activity is mediated by alterations in chromatin organization. In addition, chromatin organization may be governed in part by interactions with structural components of the nucleus. The nuclear lamins comprise the lamina and a variety of nucleoplasmic assemblies that together are major structural components of the nucleus. Furthermore, lamins and lamin-associated proteins have been reported to bind chromatin. These observations suggest that the nuclear lamins may be involved in the regulation of gene activity. In this report, we test this possibility by disrupting the normal organization of nuclear lamins with a dominant negative lamin mutant lacking the NH2-terminal domain. We find that this disruption inhibits RNA polymerase II activity in both mammalian cells and transcriptionally active embryonic nuclei from Xenopus laevis. The inhibition appears to be specific for polymerase II as disruption of lamin organization does not detectably inhibit RNA polymerases I and III. Furthermore, immunofluorescence observations indicate that this selective inhibition of polymerase II-dependent transcription involves the TATA binding protein, a component of the basal transcription factor TFIID.
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Affiliation(s)
- Timothy P Spann
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
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37
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Lopez-Soler RI, Moir RD, Spann TP, Stick R, Goldman RD. A role for nuclear lamins in nuclear envelope assembly. J Cell Biol 2001; 154:61-70. [PMID: 11448990 PMCID: PMC2196852 DOI: 10.1083/jcb.200101025] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2001] [Revised: 05/15/2001] [Accepted: 06/05/2001] [Indexed: 11/30/2022] Open
Abstract
The molecular interactions responsible for nuclear envelope assembly after mitosis are not well understood. In this study, we demonstrate that a peptide consisting of the COOH-terminal domain of Xenopus lamin B3 (LB3T) prevents nuclear envelope assembly in Xenopus interphase extracts. Specifically, LB3T inhibits chromatin decondensation and blocks the formation of both the nuclear lamina-pore complex and nuclear membranes. Under these conditions, some vesicles bind to the peripheral regions of the chromatin. These "nonfusogenic" vesicles lack lamin B3 (LB3) and do not bind LB3T; however, "fusogenic" vesicles containing LB3 can bind LB3T, which blocks their association with chromatin and, subsequently, nuclear membrane assembly. LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3. Additionally, we show that LB3T inhibits normal lamin polymerization in vitro. These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.
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Affiliation(s)
- R I Lopez-Soler
- Department of Cell and Molecular Biology, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
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38
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Moir RD, Yoon M, Khuon S, Goldman RD. Nuclear lamins A and B1: different pathways of assembly during nuclear envelope formation in living cells. J Cell Biol 2000; 151:1155-68. [PMID: 11121432 PMCID: PMC2190592 DOI: 10.1083/jcb.151.6.1155] [Citation(s) in RCA: 289] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/1999] [Accepted: 10/06/2000] [Indexed: 01/31/2023] Open
Abstract
At the end of mitosis, the nuclear lamins assemble to form the nuclear lamina during nuclear envelope formation in daughter cells. We have fused A- and B-type nuclear lamins to the green fluorescent protein to study this process in living cells. The results reveal that the A- and B-type lamins exhibit different pathways of assembly. In the early stages of mitosis, both lamins are distributed throughout the cytoplasm in a diffusible (nonpolymerized) state, as demonstrated by fluorescence recovery after photobleaching (FRAP). During the anaphase-telophase transition, lamin B1 begins to become concentrated at the surface of the chromosomes. As the chromosomes reach the spindle poles, virtually all of the detectable lamin B1 has accumulated at their surfaces. Subsequently, this lamin rapidly encloses the entire perimeter of the region containing decondensing chromosomes in each daughter cell. By this time, lamin B1 has assembled into a relatively stable polymer, as indicated by FRAP analyses and insolubility in detergent/high ionic strength solutions. In contrast, the association of lamin A with the nucleus begins only after the major components of the nuclear envelope including pore complexes are assembled in daughter cells. Initially, lamin A is found in an unpolymerized state throughout the nucleoplasm of daughter cell nuclei in early G1 and only gradually becomes incorporated into the peripheral lamina during the first few hours of this stage of the cell cycle. In later stages of G1, FRAP analyses suggest that both green fluorescent protein lamins A and B1 form higher order polymers throughout interphase nuclei.
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Affiliation(s)
- Robert D. Moir
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Miri Yoon
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Satya Khuon
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
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Alsheimer M, von Glasenapp E, Schnolzer M, Heid H, Benavente R. Meiotic lamin C2: the unique amino-terminal hexapeptide GNAEGR is essential for nuclear envelope association. Proc Natl Acad Sci U S A 2000; 97:13120-5. [PMID: 11078531 PMCID: PMC27188 DOI: 10.1073/pnas.240466597] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2000] [Accepted: 10/02/2000] [Indexed: 11/18/2022] Open
Abstract
Meiotic lamin C2 is the only A-type lamin expressed during mammalian spermatogenesis. Typical for this short lamin is the unique hexapeptide GNAEGR, which substitutes the nonhelical amino terminus and part of the alpha-helical rod domain present in somatic lamins. Meiotic lamin C2 also lacks a carboxyl-terminal CaaX box, which is modified by isoprenylation and involved in nuclear envelope (NE) association of somatic isoforms. The mechanism by which lamin C2 becomes localized in the NE is totally unknown. Here we demonstrate that the hexapeptide GNAEGR is essential for this process: (i) Its deletion resulted in a diffuse distribution of lamin C2 within nuclei of transfected COS-7 cells; (ii) Mutated somatic lamin C, containing the sequence GNAEGR at its amino terminus, was located at the NE. The mass spectrometric analysis of the amino terminus of lamin C2 revealed that it is modified by myristoylation. Correspondingly, the substitution of the first glycine residue abolishes the NE association of lamin C2. We conclude that NE association of lamin C2 is achieved by a mechanism different from that of somatic lamins.
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Affiliation(s)
- M Alsheimer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
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40
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Dechat T, Korbei B, Vaughan OA, Vlcek S, Hutchison CJ, Foisner R. Lamina-associated polypeptide 2alpha binds intranuclear A-type lamins. J Cell Sci 2000; 113 Pt 19:3473-84. [PMID: 10984438 DOI: 10.1242/jcs.113.19.3473] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleoskeletal protein lamina-associated polypeptide 2(α) (LAP2*) contains a large, unique C terminus and differs significantly from its alternatively spliced, mostly membrane-integrated isoforms, such as LAP2beta. Unlike lamin B-binding LAP2beta, LAP2alpha was found by confocal immunofluorescence microscopy to colocalize preferentially with A-type lamins in the newly formed nuclei assembled after mitosis. While only a subfraction of lamins A and C (lamin A/C) was associated with the predominantly nuclear LAP2alpha in telophase, the majority of lamin A/C colocalized with LAP2alpha in G(1)-phase nuclei. Furthermore, selective disruption of A-type lamin structures by overexpression of lamin mutants in HeLa cells caused a redistribution of LAP2alpha. Coimmunoprecipitation experiments revealed that a fraction of lamin A/C formed a stable, SDS-resistant complex with LAP2alpha in interphase cells and in postmetaphase cell extracts. Blot overlay binding studies revealed a direct binding of LAP2alpha to exclusively A-type lamins and located the interaction domains to the C-terminal 78 amino acids of LAP2alpha and to residues 319–566 in lamin A/C, which include the C terminus of the rod and the entire tail common to lamin A/C. These findings suggest that LAP2alpha and A-type lamins cooperate in the organization of internal nuclear structures.
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Affiliation(s)
- T Dechat
- Department of Biochemistry and Molecular Cell Biology, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
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41
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Lee KK, Gruenbaum Y, Spann P, Liu J, Wilson KL. C. elegans nuclear envelope proteins emerin, MAN1, lamin, and nucleoporins reveal unique timing of nuclear envelope breakdown during mitosis. Mol Biol Cell 2000; 11:3089-99. [PMID: 10982402 PMCID: PMC14977 DOI: 10.1091/mbc.11.9.3089] [Citation(s) in RCA: 130] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Emerin, MAN1, and LAP2 are integral membrane proteins of the vertebrate nuclear envelope. They share a 43-residue N-terminal motif termed the LEM domain. We found three putative LEM domain genes in Caenorhabditis elegans, designated emr-1, lem-2, and lem-3. We analyzed emr-l, which encodes Ce-emerin, and lem-2, which encodes Ce-MAN1. Ce-emerin and Ce-MAN1 migrate on SDS-PAGE as 17- and 52-kDa proteins, respectively. Based on their biochemical extraction properties and immunolocalization, both Ce-emerin and Ce-MAN1 are integral membrane proteins localized at the nuclear envelope. We used antibodies against Ce-MAN1, Ce-emerin, nucleoporins, and Ce-lamin to determine the timing of nuclear envelope breakdown during mitosis in C. elegans. The C. elegans nuclear envelope disassembles very late compared with vertebrates and Drosophila. The nuclear membranes remained intact everywhere except near spindle poles during metaphase and early anaphase, fully disassembling only during mid-late anaphase. Disassembly of pore complexes, and to a lesser extent the lamina, depended on embryo age: pore complexes were absent during metaphase in >30-cell embryos but existed until anaphase in 2- to 24-cell embryos. Intranuclear mRNA splicing factors disassembled after prophase. The timing of nuclear disassembly in C. elegans is novel and may reflect its evolutionary position between unicellular and more complex eukaryotes.
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Affiliation(s)
- K K Lee
- Department of Cell Biology and Anatomy, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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42
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Moir RD, Spann TP, Herrmann H, Goldman RD. Disruption of nuclear lamin organization blocks the elongation phase of DNA replication. J Cell Biol 2000; 149:1179-92. [PMID: 10851016 PMCID: PMC2175110 DOI: 10.1083/jcb.149.6.1179] [Citation(s) in RCA: 168] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/1999] [Accepted: 05/01/2000] [Indexed: 11/22/2022] Open
Abstract
The role of nuclear lamins in DNA replication is unclear. To address this, nuclei were assembled in Xenopus extracts containing AraC, a reversible inhibitor that blocks near the onset of the elongation phase of replication. Dominant-negative lamin mutants lacking their NH(2)-terminal domains were added to assembled nuclei to disrupt lamin organization. This prevented the resumption of DNA replication after the release of the AraC block. This inhibition of replication was not due to gross disruption of nuclear envelope structure and function. The organization of initiation factors was not altered by lamin disruption, and nuclei resumed replication when transferred to extracts treated with CIP, an inhibitor of the cyclin-dependent kinase (cdk) 2-dependent step of initiation. This suggests that alteration of lamin organization does not affect the initiation phase of DNA replication. Instead, we find that disruption of lamin organization inhibited chain elongation in a dose-dependent fashion. Furthermore, the established organization of two elongation factors, proliferating cell nuclear antigen, and replication factor complex, was disrupted by DeltaNLA. These findings demonstrate that lamin organization must be maintained in nuclei for the elongation phase of DNA replication to proceed.
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Affiliation(s)
- Robert D. Moir
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Timothy P. Spann
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
| | - Harald Herrmann
- Division of Cell Biology, German Cancer Research Center, D-69120 Heidelberg, Germany
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611
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43
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Ivanović-Matić S, Dinić S, Vujosević M, Poznanović G. The protein composition of the hepatocyte nuclear matrix is differentiation-stage specific. IUBMB Life 2000; 49:511-7. [PMID: 11032245 DOI: 10.1080/15216540050167052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The protein composition of hepatocyte nuclear matrices was examined in rats from the 16th day of gestation to 75 days after birth (adult). An overall increase in size of the nuclear matrix was accompanied by quantitative and qualitative changes in its protein content. Quantitative changes of the major proteins of the peripheral lamina surrounding the isolated nuclear matrix were detected. By Western analysis we established that in pre- and postnatal nuclear matrices the relative concentrations of lamin C were greater than lamin A. After birth, the relative concentrations of both lamins progressively increased. In the adult nuclear matrix, the concentration of lamin A was greater than lamin C. In contrast, the relative concentrations of lamin B remained unchanged throughout development and growth. The relative concentrations of two nuclear matrix-associated regulatory proteins studied changed with development and growth: transcription factor C/EBPalpha isoforms, which were detected during the gestation period, increased notably after the first postnatal day, attaining a maximum at the adult stage; the high concentrations of the proliferating cell nuclear antigen (PCNA) perceptibly decreased after the 21st prenatal day. Changes in the composition of the nuclear matrix protein suggest that this structure coordinates nuclear functioning during cell differentiation.
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Affiliation(s)
- S Ivanović-Matić
- Molecular Biology Laboratory, Institute for Biological Research, Belgrade, Serbia, Federal Republic of Yugoslavia
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44
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Ko YG, Kang YS, Kim EK, Park SG, Kim S. Nucleolar localization of human methionyl-tRNA synthetase and its role in ribosomal RNA synthesis. J Cell Biol 2000; 149:567-74. [PMID: 10791971 PMCID: PMC2174846 DOI: 10.1083/jcb.149.3.567] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Human aminoacyl-tRNA synthetases (ARSs) are normally located in cytoplasm and are involved in protein synthesis. In the present work, we found that human methionyl-tRNA synthetase (MRS) was translocated to nucleolus in proliferative cells, but disappeared in quiescent cells. The nucleolar localization of MRS was triggered by various growth factors such as insulin, PDGF, and EGF. The presence of MRS in nucleoli depended on the integrity of RNA and the activity of RNA polymerase I in the nucleolus. The ribosomal RNA synthesis was specifically decreased by the treatment of anti-MRS antibody as determined by nuclear run-on assay and immunostaining with anti-Br antibody after incorporating Br-UTP into nascent RNA. Thus, human MRS plays a role in the biogenesis of rRNA in nucleoli, while it is catalytically involved in protein synthesis in cytoplasm.
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Affiliation(s)
- Young-Gyu Ko
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Young-Sun Kang
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Eun-Kyoung Kim
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Sang Gyu Park
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
| | - Sunghoon Kim
- National Creative Research Initiatives Center for ARS Network, Sung Kyun Kwan University, Jangangu, Suwon, Kyunggido 440-746, Korea
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45
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Abstract
Apoptosis is a form of cell death that takes place under physiologic conditions, and plays a key role in the control of biological processes such as embryonic development, tissue remodelation and renewal, or regulation of cell populations. Since its discovery in the early 1970s, there have been many relevant advances in the knowledge of the biochemical and molecular events involved in apoptosis. However, although the apoptotic process was defined on the basis of morphologic observations, only recently have we started to elucidate the molecular mechanisms that drive the structural changes observed in cells undergoing apoptosis. The article reviews current knowledge about the implications of cytoskeleton components (microfilaments, intermediate filaments, microtubules, and other cytoskeleton-related proteins) in the dynamics of apoptosis.
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Affiliation(s)
- R Atencia
- Departamento de Biologia Celular, Facultad de Medicina, Universidad del País Vasco/EHU, Leioa, España
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46
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Haraguchi T, Koujin T, Hayakawa T, Kaneda T, Tsutsumi C, Imamoto N, Akazawa C, Sukegawa J, Yoneda Y, Hiraoka Y. Live fluorescence imaging reveals early recruitment of emerin, LBR, RanBP2, and Nup153 to reforming functional nuclear envelopes. J Cell Sci 2000; 113 ( Pt 5):779-94. [PMID: 10671368 DOI: 10.1242/jcs.113.5.779] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We determined the times when the nuclear membrane, nuclear pore complex (NPC) components, and nuclear import function were recovered during telophase in living HeLa cells. Simultaneous observation of fluorescently-labeled NLS-bearing proteins, lamin B receptor (LBR)-GFP, and Hoechst33342-stained chromosomes revealed that nuclear membranes reassembled around chromosomes by 5 minutes after the onset of anaphase (early telophase) whereas nuclear import function was recovered later, at 8 minutes. GFP-tagged emerin also accumulated on chromosomes 5 minutes after the onset of anaphase. Interestingly, emerin and LBR initially accumulated at distinct, separate locations, but then became uniform 8 minutes after the onset of anaphase, concurrent with the recovery of nuclear import function. We further determined the timing of NPC assembly by immunofluorescence staining of cells fixed at precise times after the onset of anaphase. Taken together, these results showed that emerin, LBR, and several NPC components (RanBP2, Nup153, p62), but not Tpr, reconstitute around chromosomes very early in telophase prior to the recovery of nuclear import activity.
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Affiliation(s)
- T Haraguchi
- Kansai Advanced Research Center, Communications Research Laboratory, CREST Research Project, Japan Science and Technology Corporation, Iwaoka-cho, Nishi-ku, Kobe 651-2492, Japan.
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47
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Kowluru A. Evidence for the carboxyl methylation of nuclear lamin-B in the pancreatic beta cell. Biochem Biophys Res Commun 2000; 268:249-54. [PMID: 10679189 DOI: 10.1006/bbrc.2000.2107] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lamins are intermediate filament proteins that constitute the main components of the lamina underlying the inner-nuclear membrane and serve to organize chromatin. Lamins (e.g., lamin-B) undergo posttranslational modifications (e.g., isoprenylation and methylation) at their C-terminal cysteine. Such modifications are thought to render optimal association of lamins with the nuclear envelop. Herein, we examined whether nuclear lamin-B undergoes carboxyl methylation in islet beta cells. A 65- to 70-kDa protein was carboxyl methylated in intact rat islets and clonal beta (HIT or INS) cells or in homogenates which could be immunoprecipitated using lamin-B antiserum. Incubation of purified HIT cell-nuclear fraction with [(3)H]S-adenosyl methionine yielded a single carboxyl methylated protein peak (ca. 65-70 kDa); this protein was immunologically identified as lamin-B. Several methylation inhibitors, including acetyl farnesyl cysteine, a competitive inhibitor of protein prenyl cysteine methylation, inhibited the carboxyl methylation of lamin-B, indicating that the carboxyl-methylated amino acid is cysteine. These findings, together with our recent observations demonstrating that inhibition of protein isoprenylation causes apoptotic death of the pancreatic beta cell, raise an interesting possibility that inhibition of C-terminal cysteine modifications of lamin-B might result in disruption of nuclear assembly, leading to further propagation of apoptotic signals, including DNA fragmentation and chromatin condensation.
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Affiliation(s)
- A Kowluru
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48202, USA.
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48
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Jagatheesan G, Thanumalayan S, Muralikrishna B, Rangaraj N, Karande AA, Parnaik VK. Colocalization of intranuclear lamin foci with RNA splicing factors. J Cell Sci 1999; 112 ( Pt 24):4651-61. [PMID: 10574713 DOI: 10.1242/jcs.112.24.4651] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The lamins form a fibrous network underlying the inner nuclear membrane termed the nuclear lamina. In order to gain insights into the role of lamins in nuclear organization, we have characterized a monoclonal antibody (LA-2H10) raised against recombinant rat lamin A that labels nuclei in a speckled pattern in all cells of unsynchronized populations of HeLa and rat F-111 fibroblast cells, unlike the typical nuclear periphery staining by another monoclonal antibody to lamin A, LA-2B3. In immunolocalization studies the lamin A speckles or foci were found to colocalize with the RNA splicing factors SC-35 and U5-116 kD, but not with p80 coilin found in coiled bodies. Lamin B1 was also associated with these foci. These foci dispersed when cells entered mitosis and reformed during anaphase. The differential reactivity of LA-2H10 and LA-2B3 was retained after nuclei were extracted with detergents, nucleases and salt to disrupt interactions of lamins with chromatin and other nuclear proteins. Using deletion fragments of recombinant lamin A, the epitope recognized by LA-2H10 was located between amino acids 171 and 246. Our findings are consistent with a structural role for lamins in supporting nuclear compartments containing proteins involved in RNA splicing.
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Affiliation(s)
- G Jagatheesan
- Centre for Cellular and Molecular Biology, Hyderabad 500 007, India
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49
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Goldman RD, Chou YH, Prahlad V, Yoon M. Intermediate filaments: dynamic processes regulating their assembly, motility, and interactions with other cytoskeletal systems. FASEB J 1999; 13 Suppl 2:S261-5. [PMID: 10619140 DOI: 10.1096/fasebj.13.9002.s261] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- R D Goldman
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA.
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50
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Sullivan T, Escalante-Alcalde D, Bhatt H, Anver M, Bhat N, Nagashima K, Stewart CL, Burke B. Loss of A-type lamin expression compromises nuclear envelope integrity leading to muscular dystrophy. J Cell Biol 1999; 147:913-20. [PMID: 10579712 PMCID: PMC2169344 DOI: 10.1083/jcb.147.5.913] [Citation(s) in RCA: 919] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The nuclear lamina is a protein meshwork lining the nucleoplasmic face of the inner nuclear membrane and represents an important determinant of interphase nuclear architecture. Its major components are the A- and B-type lamins. Whereas B-type lamins are found in all mammalian cells, A-type lamin expression is developmentally regulated. In the mouse, A-type lamins do not appear until midway through embryonic development, suggesting that these proteins may be involved in the regulation of terminal differentiation. Here we show that mice lacking A-type lamins develop to term with no overt abnormalities. However, their postnatal growth is severely retarded and is characterized by the appearance of muscular dystrophy. This phenotype is associated with ultrastructural perturbations to the nuclear envelope. These include the mislocalization of emerin, an inner nuclear membrane protein, defects in which are implicated in Emery-Dreifuss muscular dystrophy (EDMD), one of the three major X-linked dystrophies. Mice lacking the A-type lamins exhibit tissue-specific alterations to their nuclear envelope integrity and emerin distribution. In skeletal and cardiac muscles, this is manifest as a dystrophic condition related to EDMD.
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Affiliation(s)
- Teresa Sullivan
- Advanced BioScience Laboratories–Basic Research Program, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Diana Escalante-Alcalde
- Advanced BioScience Laboratories–Basic Research Program, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | | | - Miriam Anver
- Science Applications International Corporation, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Narayan Bhat
- Science Applications International Corporation, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Kunio Nagashima
- Science Applications International Corporation, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Colin L. Stewart
- Advanced BioScience Laboratories–Basic Research Program, National Cancer Institute–Frederick Cancer Research and Development Center, Frederick, Maryland 21702
| | - Brian Burke
- Department of Cell Biology and Anatomy, University of Calgary, Faculty of Medicine, Calgary, Canada T2N 4N1
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