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Wallace M, Fedorchak GR, Agrawal R, Gilbert RM, Patel J, Park S, Paszek M, Lammerding J. The lamin A/C Ig-fold undergoes cell density-dependent changes that alter epitope binding. Nucleus 2023; 14:2180206. [PMID: 36809122 PMCID: PMC9980629 DOI: 10.1080/19491034.2023.2180206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023] Open
Abstract
Lamins A/C are nuclear intermediate filament proteins that are involved in diverse cellular mechanical and biochemical functions. Here, we report that recognition of Lamins A/C by a commonly used antibody (JOL-2) that binds the Lamin A/C Ig-fold and other antibodies targeting similar epitopes is highly dependent on cell density, even though Lamin A/Clevels do not change. We propose that the effect is caused by partial unfolding or masking of the C'E and/or EF loops of the Ig-fold in response to cell spreading. Surprisingly, JOL-2 antibody labeling was insensitive to disruption of cytoskeletal filaments or the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Furthermore, neither nuclear stiffness nor nucleo-cytoskeletal force transmission changed with cell density. These findings are important for the interpretation of immunofluorescence data for Lamin A/C and also raise the intriguing prospect that the conformational changes may play a role in Lamin A/C mediated cellular function.
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Affiliation(s)
- Melanie Wallace
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA,Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA
| | - Gregory R. Fedorchak
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA,Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA
| | - Richa Agrawal
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA,Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA
| | - Rachel M. Gilbert
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA,Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA
| | - Jineet Patel
- Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA
| | - Sangwoo Park
- Graduate Field of Biophysics, Cornell University, Ithaca, NY, USA
| | - Matthew Paszek
- Graduate Field of Biophysics, Cornell University, Ithaca, NY, USA,Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA
| | - Jan Lammerding
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, USA,Weill Institute for Cell and Molecular Biology, Ithaca, NY, USA,CONTACT Jan Lammerding Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY14853, USA
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2
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Kristiani L, Kim Y. The Interplay between Oxidative Stress and the Nuclear Lamina Contributes to Laminopathies and Age-Related Diseases. Cells 2023; 12:cells12091234. [PMID: 37174634 PMCID: PMC10177617 DOI: 10.3390/cells12091234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 04/23/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Oxidative stress is a physiological condition that arises when there is an imbalance between the production of reactive oxygen species (ROS) and the ability of cells to neutralize them. ROS can damage cellular macromolecules, including lipids, proteins, and DNA, leading to cellular senescence and physiological aging. The nuclear lamina (NL) is a meshwork of intermediate filaments that provides structural support to the nucleus and plays crucial roles in various nuclear functions, such as DNA replication and transcription. Emerging evidence suggests that oxidative stress disrupts the integrity and function of the NL, leading to dysregulation of gene expression, DNA damage, and cellular senescence. This review highlights the current understanding of the interplay between oxidative stress and the NL, along with its implications for human health. Specifically, elucidation of the mechanisms underlying the interplay between oxidative stress and the NL is essential for the development of effective treatments for laminopathies and age-related diseases.
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Affiliation(s)
- Lidya Kristiani
- Department of Biomedicine, School of Life Science, Indonesia International Institute for Life Science, Jakarta 13210, Indonesia
| | - Youngjo Kim
- Department of Integrated Biomedical Science, Soonchunhyang Institute of Medi-Bioscience, Soonchunhyang University, Cheonan 31151, Republic of Korea
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3
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Zhang Y, Lin Y, Zhang Y, Wang Y, Li Z, Zhu Y, Liu H, Ju W, Cui C, Chen M. Familial atrial myopathy in a large multigenerational heart-hand syndrome pedigree carrying an LMNA missense variant in rod 2B domain (p.R335W). Heart Rhythm 2021; 19:466-475. [PMID: 34808346 DOI: 10.1016/j.hrthm.2021.11.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 02/02/2023]
Abstract
BACKGROUND The literature on laminopathy with ventricular phenotype is extensive. However, the pathogenicity of LMNA variations in atrial lesions still lacks research. OBJECTIVE The purpose of this study was to characterize the atrial phenotypes and possible mechanisms in a large Chinese family with heart-hand syndrome carrying a LMNA missense variant in rod 2B domain (c.1003C>T p.R335W). METHODS Clinical characteristics were collected on the basis of the pedigree investigation. Comprehensive functional analyses, including molecular dynamic (MD) simulation, cellular, and animal functional assays, determined the pathogenicity in atrial myopathy. RESULTS In the pedigree investigation, 6 of 13 of the mutation carriers showed heterogeneous cardiac phenotypes and 8 carriers also had brachydactyly. In silico molecular dynamics simulations predicted increased binding energy of the R335W mutant lamin A. Atrial cardiomyocytes (HL-1, human induced pluripotent stem cell-derived atrial cardiomyocytes) expressing R335W showed abnormal nuclear morphology, compromised DNA repair, and dysfunctional contraction. Adult zebrafish expressing mutant lamin A showed increased P wave duration in the electrocardiogram, decreased peak A wave velocity in echocardiography, and atrial lesions under the transmission electron microscope. CONCLUSION LMNA p.R335W mutation leads to familial heart-hand syndrome characterized by an overlapping phenotype of prominent atrial lesions and brachydactyly. The unstable lamin dimerization and impaired DNA repair are possible mechanisms underlying cardiac phenotypes. Our findings consolidated the genetic role in the course of atrial arrhythmias and cardiac aging, which is helpful in the diagnosis and treatment of cardiac laminopathy.
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Affiliation(s)
- Yike Zhang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yongping Lin
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yanjuan Zhang
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yuanqing Wang
- Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Zhaomin Li
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yue Zhu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hailei Liu
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Weizhu Ju
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Chang Cui
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
| | - Minglong Chen
- Department of Cardiology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China; Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, China.
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4
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Ahn J, Lee J, Jeong S, Kang SM, Park BJ, Ha NC. Beta-strand-mediated dimeric formation of the Ig-like domains of human lamin A/C and B1. Biochem Biophys Res Commun 2021; 550:191-196. [PMID: 33706103 DOI: 10.1016/j.bbrc.2021.02.102] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 02/22/2021] [Indexed: 10/22/2022]
Abstract
Lamins are nuclear intermediate filament proteins that play an essential role in maintaining the nuclear structure by forming a 3-D meshwork. Lamins consist of the N-terminal unstructured head, the coiled-coil rod domain, and the C-terminal tail, which is mostly unstructured except for the Ig-like domain. To date, the Ig-like domain has been characterized as a monomeric structure. Here, we determined the crystal structures of human lamin A/C, including the Ig-like domain and its N- and C-terminal flanking sequences. Interestingly, the structures showed a homodimer formed by beta-strand interactions between the N- and C-terminal flanking sequences. This interaction also provides a molecular implication for the creation of a 3-D meshwork between the 3.5-nm-thick filaments. Furthermore, we determined the crystal structure of the corresponding region of lamin B1. The structure showed a similar dimeric assembly, also formed by beta-strand interactions, albeit the intersubunit distance was much shorter. Since the Ig-like domain contains many genetic hotspots causing lamin-related diseases in lamin A/C, our findings will help understand the detailed assembly of lamins in a 3-D meshwork structure and lamin-related diseases at the molecular level.
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Affiliation(s)
- Jinsook Ahn
- Department of Agricultural Biotechnology, Centre for Food Safety and Toxicology, Centre for Food and Bioconvergence, Research Institute for Agriculture and Life Sciences, CALS, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jinwook Lee
- Department of Agricultural Biotechnology, Centre for Food Safety and Toxicology, Centre for Food and Bioconvergence, Research Institute for Agriculture and Life Sciences, CALS, Seoul National University, Seoul, 08826, Republic of Korea
| | - Soyeon Jeong
- Department of Agricultural Biotechnology, Centre for Food Safety and Toxicology, Centre for Food and Bioconvergence, Research Institute for Agriculture and Life Sciences, CALS, Seoul National University, Seoul, 08826, Republic of Korea
| | - So-Mi Kang
- Department of Molecular Biology, College of Natural Science, Pusan National University, Busan, 46241, Republic of Korea
| | - Bum-Joon Park
- Department of Molecular Biology, College of Natural Science, Pusan National University, Busan, 46241, Republic of Korea
| | - Nam-Chul Ha
- Department of Agricultural Biotechnology, Centre for Food Safety and Toxicology, Centre for Food and Bioconvergence, Research Institute for Agriculture and Life Sciences, CALS, Seoul National University, Seoul, 08826, Republic of Korea.
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Varlet AA, Helfer E, Badens C. Molecular and Mechanobiological Pathways Related to the Physiopathology of FPLD2. Cells 2020; 9:cells9091947. [PMID: 32842478 PMCID: PMC7565540 DOI: 10.3390/cells9091947] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/15/2022] Open
Abstract
Laminopathies are rare and heterogeneous diseases affecting one to almost all tissues, as in Progeria, and sharing certain features such as metabolic disorders and a predisposition to atherosclerotic cardiovascular diseases. These two features are the main characteristics of the adipose tissue-specific laminopathy called familial partial lipodystrophy type 2 (FPLD2). The only gene that is involved in FPLD2 physiopathology is the LMNA gene, with at least 20 mutations that are considered pathogenic. LMNA encodes the type V intermediate filament lamin A/C, which is incorporated into the lamina meshwork lining the inner membrane of the nuclear envelope. Lamin A/C is involved in the regulation of cellular mechanical properties through the control of nuclear rigidity and deformability, gene modulation and chromatin organization. While recent studies have described new potential signaling pathways dependent on lamin A/C and associated with FPLD2 physiopathology, the whole picture of how the syndrome develops remains unknown. In this review, we summarize the signaling pathways involving lamin A/C that are associated with the progression of FPLD2. We also explore the links between alterations of the cellular mechanical properties and FPLD2 physiopathology. Finally, we introduce potential tools based on the exploration of cellular mechanical properties that could be redirected for FPLD2 diagnosis.
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Affiliation(s)
- Alice-Anaïs Varlet
- Marseille Medical Genetics (MMG), INSERM, Aix Marseille University, 13005 Marseille, France;
| | - Emmanuèle Helfer
- Centre Interdisciplinaire de Nanoscience de Marseille (CINAM), CNRS, Aix Marseille University, 13009 Marseille, France
- Correspondence: (E.H.); (C.B.); Tel.: +33-6-60-30-28-91 (E.H.); +33-4-91-78-68-94 (C.B.)
| | - Catherine Badens
- Marseille Medical Genetics (MMG), INSERM, Aix Marseille University, 13005 Marseille, France;
- Correspondence: (E.H.); (C.B.); Tel.: +33-6-60-30-28-91 (E.H.); +33-4-91-78-68-94 (C.B.)
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6
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Lamin A/C Mechanotransduction in Laminopathies. Cells 2020; 9:cells9051306. [PMID: 32456328 PMCID: PMC7291067 DOI: 10.3390/cells9051306] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 05/20/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022] Open
Abstract
Mechanotransduction translates forces into biological responses and regulates cell functionalities. It is implicated in several diseases, including laminopathies which are pathologies associated with mutations in lamins and lamin-associated proteins. These pathologies affect muscle, adipose, bone, nerve, and skin cells and range from muscular dystrophies to accelerated aging. Although the exact mechanisms governing laminopathies and gene expression are still not clear, a strong correlation has been found between cell functionality and nuclear behavior. New theories base on the direct effect of external force on the genome, which is indeed sensitive to the force transduced by the nuclear lamina. Nuclear lamina performs two essential functions in mechanotransduction pathway modulating the nuclear stiffness and governing the chromatin remodeling. Indeed, A-type lamin mutation and deregulation has been found to affect the nuclear response, altering several downstream cellular processes such as mitosis, chromatin organization, DNA replication-transcription, and nuclear structural integrity. In this review, we summarize the recent findings on the molecular composition and architecture of the nuclear lamina, its role in healthy cells and disease regulation. We focus on A-type lamins since this protein family is the most involved in mechanotransduction and laminopathies.
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7
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Looking at New Unexpected Disease Targets in LMNA-Linked Lipodystrophies in the Light of Complex Cardiovascular Phenotypes: Implications for Clinical Practice. Cells 2020; 9:cells9030765. [PMID: 32245113 PMCID: PMC7140635 DOI: 10.3390/cells9030765] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/01/2020] [Accepted: 03/07/2020] [Indexed: 12/13/2022] Open
Abstract
Variants in LMNA, encoding A-type lamins, are responsible for laminopathies including muscular dystrophies, lipodystrophies, and progeroid syndromes. Cardiovascular laminopathic involvement is classically described as cardiomyopathy in striated muscle laminopathies, and arterial wall dysfunction and/or valvulopathy in lipodystrophic and/or progeroid laminopathies. We report unexpected cardiovascular phenotypes in patients with LMNA-associated lipodystrophies, illustrating the complex multitissular pathophysiology of the disease and the need for specific cardiovascular investigations in affected patients. A 33-year-old woman was diagnosed with generalized lipodystrophy and atypical progeroid syndrome due to the newly identified heterozygous LMNA p.(Asp136Val) variant. Her complex cardiovascular phenotype was associated with atherosclerosis, aortic valvular disease and left ventricular hypertrophy with rhythm and conduction defects. A 29-year-old woman presented with a partial lipodystrophy syndrome and a severe coronary atherosclerosis which required a triple coronary artery bypass grafting. She carried the novel heterozygous p.(Arg60Pro) LMNA variant inherited from her mother, affected with partial lipodystrophy and dilated cardiomyopathy. Different lipodystrophy-associated LMNA pathogenic variants could target cardiac vasculature and/or muscle, leading to complex overlapping phenotypes. Unifying pathophysiological hypotheses should be explored in several cell models including adipocytes, cardiomyocytes and vascular cells. Patients with LMNA-associated lipodystrophy should be systematically investigated with 24-h ECG monitoring, echocardiography and non-invasive coronary function testing.
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8
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Briand N, Collas P. Laminopathy-causing lamin A mutations reconfigure lamina-associated domains and local spatial chromatin conformation. Nucleus 2019. [PMID: 29517398 PMCID: PMC5973257 DOI: 10.1080/19491034.2018.1449498] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The nuclear lamina contributes to the regulation of gene expression and to chromatin organization. Mutations in A-type nuclear lamins cause laminopathies, some of which are associated with a loss of heterochromatin at the nuclear periphery. Until recently however, little if any information has been provided on where and how lamin A interacts with the genome and on how disease-causing lamin A mutations may rearrange genome conformation. Here, we review aspects of nuclear lamin association with the genome. We highlight recent evidence of reorganization of lamin A-chromatin interactions in cellular models of laminopathies, and implications on the 3-dimensional rearrangement of chromatin in these models, including patient cells. We discuss how a hot-spot lipodystrophic lamin A mutation alters chromatin conformation and epigenetic patterns at an anti-adipogenic locus, and conclude with remarks on links between lamin A, Polycomb and the pathophysiology of laminopathies. The recent findings presented here collectively argue towards a deregulation of large-scale and local spatial genome organization by a subset of lamin A mutations causing laminopathies.
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Affiliation(s)
- Nolwenn Briand
- a Department of Molecular Medicine , Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo , Norway
| | - Philippe Collas
- a Department of Molecular Medicine , Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Oslo , Norway.,b Norwegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine , Oslo University Hospital , Oslo , Norway
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9
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Vigouroux C, Guénantin AC, Vatier C, Capel E, Le Dour C, Afonso P, Bidault G, Béréziat V, Lascols O, Capeau J, Briand N, Jéru I. Lipodystrophic syndromes due to LMNA mutations: recent developments on biomolecular aspects, pathophysiological hypotheses and therapeutic perspectives. Nucleus 2019; 9:235-248. [PMID: 29578370 PMCID: PMC5973242 DOI: 10.1080/19491034.2018.1456217] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mutations in LMNA, encoding A-type lamins, are responsible for laminopathies including muscular dystrophies, lipodystrophies, and premature ageing syndromes. LMNA mutations have been shown to alter nuclear structure and stiffness, binding to partners at the nuclear envelope or within the nucleoplasm, gene expression and/or prelamin A maturation. LMNA-associated lipodystrophic features, combining generalized or partial fat atrophy and metabolic alterations associated with insulin resistance, could result from altered adipocyte differentiation or from altered fat structure. Recent studies shed some light on how pathogenic A-type lamin variants could trigger lipodystrophy, metabolic complications, and precocious cardiovascular events. Alterations in adipose tissue extracellular matrix and TGF-beta signaling could initiate metabolic inflexibility. Premature senescence of vascular cells could contribute to cardiovascular complications. In affected families, metabolic alterations occur at an earlier age across generations, which could result from epigenetic deregulation induced by LMNA mutations. Novel cellular models recapitulating adipogenic developmental pathways provide scalable tools for disease modeling and therapeutic screening.
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Affiliation(s)
- Corinne Vigouroux
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,b Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Laboratoire Commun de Biologie et Génétique Moléculaires , Paris , France.,c Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre National de Référence des Pathologies Rares de l'Insulino-Sécrétion et de l'Insulino-Sensibilité (PRISIS), Service d'Endocrinologie, Diabétologie et Endocrinologie de la Reproduction , Paris , France
| | - Anne-Claire Guénantin
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,d Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus , Hinxton , UK
| | - Camille Vatier
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,c Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre National de Référence des Pathologies Rares de l'Insulino-Sécrétion et de l'Insulino-Sensibilité (PRISIS), Service d'Endocrinologie, Diabétologie et Endocrinologie de la Reproduction , Paris , France
| | - Emilie Capel
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France
| | - Caroline Le Dour
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France
| | - Pauline Afonso
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France
| | - Guillaume Bidault
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,e University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital , Cambridge CB2 0QQ , UK
| | - Véronique Béréziat
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France
| | - Olivier Lascols
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,b Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Laboratoire Commun de Biologie et Génétique Moléculaires , Paris , France
| | - Jacqueline Capeau
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France
| | - Nolwenn Briand
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,f Department of Molecular Medicine , Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo , Blindern , Oslo , Norway
| | - Isabelle Jéru
- a Sorbonne Université, Inserm UMR_S 938, Centre de Recherche Saint-Antoine, Institut Hospitalo-Universitaire de Cardio-métabolisme et Nutrition (ICAN) , Paris , France.,b Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Laboratoire Commun de Biologie et Génétique Moléculaires , Paris , France
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10
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van Tienen FHJ, Lindsey PJ, Kamps MAF, Krapels IP, Ramaekers FCS, Brunner HG, van den Wijngaard A, Broers JLV. Assessment of fibroblast nuclear morphology aids interpretation of LMNA variants. Eur J Hum Genet 2018; 27:389-399. [PMID: 30420677 DOI: 10.1038/s41431-018-0294-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 10/12/2018] [Accepted: 10/16/2018] [Indexed: 01/26/2023] Open
Abstract
The phenotypic heterogeneity of Lamin A/C (LMNA) variants renders it difficult to classify them. As a consequence, many LMNA variants are classified as variant of unknown significance (VUS). A number of studies reported different types of visible nuclear abnormalities in LMNA-variant carriers, such as herniations, honeycomb-like structures and irregular Lamin staining. In this study, we used lamin A/C immunostaining and nuclear DAPI staining to assess the number and type of nuclear abnormalities in primary dermal fibroblast cultures of laminopathy patients and healthy controls. The total number of abnormal nuclei, which includes herniations, honeycomb-structures, and donut-like nuclei, was found to be the most discriminating parameter between laminopathy and control cell cultures. The percentage abnormal nuclei was subsequently scored in fibroblasts of 28 LMNA variant carriers, ranging from (likely) benign to (likely) pathogenic variant. Using this method, 27 out of 28 fibroblast cell cultures could be classified as either normal (n = 14) or laminopathy (n = 13) and no false positive results were obtained. The obtained specificity was 100% (CI 40-100%) and sensitivity 77% (46-95%). We conclude that assessing the percentage of abnormal nuclei is a quick and reliable method, which aids classification or confirms pathogenicity of identified LMNA variants causing formation of aberrant lamin A/C protein.
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Affiliation(s)
- Florence H J van Tienen
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands. .,GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.
| | - Patrick J Lindsey
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Miriam A F Kamps
- GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Ingrid P Krapels
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Frans C S Ramaekers
- GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.,Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Han G Brunner
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands.,Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Arthur van den Wijngaard
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Jos L V Broers
- Department of Genetics and Cell Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.,CARIM-School for Cardiovascular Diseases, Maastricht University Medical Centre, Maastricht, The Netherlands
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11
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Steele-Stallard HB, Pinton L, Sarcar S, Ozdemir T, Maffioletti SM, Zammit PS, Tedesco FS. Modeling Skeletal Muscle Laminopathies Using Human Induced Pluripotent Stem Cells Carrying Pathogenic LMNA Mutations. Front Physiol 2018; 9:1332. [PMID: 30405424 PMCID: PMC6201196 DOI: 10.3389/fphys.2018.01332] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 09/04/2018] [Indexed: 01/03/2023] Open
Abstract
Laminopathies are a clinically heterogeneous group of disorders caused by mutations in LMNA. The main proteins encoded by LMNA are Lamin A and C, which together with Lamin B1 and B2, form the nuclear lamina: a mesh-like structure located underneath the inner nuclear membrane. Laminopathies show striking tissue specificity, with subtypes affecting striated muscle, peripheral nerve, and adipose tissue, while others cause multisystem disease with accelerated aging. Although several pathogenic mechanisms have been proposed, the exact pathophysiology of laminopathies remains unclear, compounded by the rarity of these disorders and lack of easily accessible cell types to study. To overcome this limitation, we used induced pluripotent stem cells (iPSCs) from patients with skeletal muscle laminopathies such as LMNA-related congenital muscular dystrophy and limb-girdle muscular dystrophy 1B, to model disease phenotypes in vitro. iPSCs can be derived from readily accessible cell types, have unlimited proliferation potential and can be differentiated into cell types that would otherwise be difficult and invasive to obtain. iPSC lines from three skeletal muscle laminopathy patients were differentiated into inducible myogenic cells and myotubes. Disease-associated phenotypes were observed in these cells, including abnormal nuclear shape and mislocalization of nuclear lamina proteins. Nuclear abnormalities were less pronounced in monolayer cultures of terminally differentiated skeletal myotubes than in proliferating myogenic cells. Notably, skeletal myogenic differentiation of LMNA-mutant iPSCs in artificial muscle constructs improved detection of myonuclear abnormalities compared to conventional monolayer cultures across multiple pathogenic genotypes, providing a high-fidelity modeling platform for skeletal muscle laminopathies. Our results lay the foundation for future iPSC-based therapy development and screening platforms for skeletal muscle laminopathies.
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Affiliation(s)
- Heather B Steele-Stallard
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.,Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Luca Pinton
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.,Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Shilpita Sarcar
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Tanel Ozdemir
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.,Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Sara M Maffioletti
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
| | - Peter S Zammit
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Francesco Saverio Tedesco
- Department of Cell and Developmental Biology, University College London, London, United Kingdom.,The Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London, United Kingdom
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12
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Insight into the functional organization of nuclear lamins in health and disease. Curr Opin Cell Biol 2018; 54:72-79. [PMID: 29800922 DOI: 10.1016/j.ceb.2018.05.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/24/2018] [Accepted: 05/08/2018] [Indexed: 11/20/2022]
Abstract
Lamins are the main component of the nuclear lamina, a protein meshwork at the inner nuclear membrane which primarily provide mechanical stability to the nucleus. Lamins, type V intermediate filament proteins, are also involved in many nuclear activities. Structural analysis of nuclei revealed that lamins form 3.5nm thick filaments often interact with nuclear pore complexes. Mutations in the LMNA gene, encoding A-type lamins, have been associated with at least 15 distinct diseases collectively termed laminopathies, including muscle, metabolic and neurological disorders, and premature aging syndrome. It is unclear how laminopathic mutations lead to such a wide array of diseases, essentially affecting almost all tissues.
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13
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Hoorntje ET, Bollen IA, Barge-Schaapveld DQ, van Tienen FH, Te Meerman GJ, Jansweijer JA, van Essen AJ, Volders PG, Constantinescu AA, van den Akker PC, van Spaendonck-Zwarts KY, Oldenburg RA, Marcelis CL, van der Smagt JJ, Hennekam EA, Vink A, Bootsma M, Aten E, Wilde AA, van den Wijngaard A, Broers JL, Jongbloed JD, van der Velden J, van den Berg MP, van Tintelen JP. Lamin A/C-Related Cardiac Disease: Late Onset With a Variable and Mild Phenotype in a Large Cohort of Patients With the Lamin A/C p.(Arg331Gln) Founder Mutation. ACTA ACUST UNITED AC 2018; 10:CIRCGENETICS.116.001631. [PMID: 28790152 DOI: 10.1161/circgenetics.116.001631] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 05/08/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Interpretation of missense variants can be especially difficult when the variant is also found in control populations. This is what we encountered for the LMNA c.992G>A (p.(Arg331Gln)) variant. Therefore, to evaluate the effect of this variant, we combined an evaluation of clinical data with functional experiments and morphological studies. METHODS AND RESULTS Clinical data of 23 probands and 35 family members carrying this variant were retrospectively collected. A time-to-event analysis was performed to compare the course of the disease with carriers of other LMNA mutations. Myocardial biopsies were studied with electron microscopy and by measuring force development of the sarcomeres. Morphology of the nuclear envelope was assessed with immunofluorescence on cultured fibroblasts. The phenotype in probands and family members was characterized by atrioventricular conduction disturbances (61% and 44%, respectively), supraventricular arrhythmias (69% and 52%, respectively), and dilated cardiomyopathy (74% and 14%, respectively). LMNA p.(Arg331Gln) carriers had a significantly better outcome regarding the composite end point (malignant ventricular arrhythmias, end-stage heart failure, or death) compared with carriers of other pathogenic LMNA mutations. A shared haplotype of 1 Mb around LMNA suggested a common founder. The combined logarithm of the odds score was 3.46. Force development in membrane-permeabilized cardiomyocytes was reduced because of decreased myofibril density. Structural nuclear LMNA-associated envelope abnormalities, that is, blebs, were confirmed by electron microscopy and immunofluorescence microscopy. CONCLUSIONS Clinical, morphological, functional, haplotype, and segregation data all indicate that LMNA p.(Arg331Gln) is a pathogenic founder mutation with a phenotype reminiscent of other LMNA mutations but with a more benign course.
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Affiliation(s)
| | - Ilse A Bollen
- For the author affiliations, please see the Appendix
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Aryan Vink
- For the author affiliations, please see the Appendix
| | | | - Emmelien Aten
- For the author affiliations, please see the Appendix
| | | | | | - Jos L Broers
- For the author affiliations, please see the Appendix
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A Novel Lamin A Mutant Responsible for Congenital Muscular Dystrophy Causes Distinct Abnormalities of the Cell Nucleus. PLoS One 2017; 12:e0169189. [PMID: 28125586 PMCID: PMC5268432 DOI: 10.1371/journal.pone.0169189] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/13/2016] [Indexed: 11/26/2022] Open
Abstract
A-type lamins, the intermediate filament proteins participating in nuclear structure and function, are encoded by LMNA. LMNA mutations can lead to laminopathies such as lipodystrophies, premature aging syndromes (progeria) and muscular dystrophies. Here, we identified a novel heterozygous LMNA p.R388P de novo mutation in a patient with a non-previously described severe phenotype comprising congenital muscular dystrophy (L-CMD) and lipodystrophy. In culture, the patient’s skin fibroblasts entered prematurely into senescence, and some nuclei showed a lamina honeycomb pattern. C2C12 myoblasts were transfected with a construct carrying the patient’s mutation; R388P-lamin A (LA) predominantly accumulated within the nucleoplasm and was depleted at the nuclear periphery, altering the anchorage of the inner nuclear membrane protein emerin and the nucleoplasmic protein LAP2-alpha. The mutant LA triggered a frequent and severe nuclear dysmorphy that occurred independently of prelamin A processing, as well as increased histone H3K9 acetylation. Nuclear dysmorphy was not significantly improved when transfected cells were treated with drugs disrupting microtubules or actin filaments or modifying the global histone acetylation pattern. Therefore, releasing any force exerted at the nuclear envelope by the cytoskeleton or chromatin did not rescue nuclear shape, in contrast to what was previously shown in Hutchinson-Gilford progeria due to other LMNA mutations. Our results point to the specific cytotoxic effect of the R388P-lamin A mutant, which is clinically related to a rare and severe multisystemic laminopathy phenotype.
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15
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Stratigi K, Chatzidoukaki O, Garinis GA. DNA damage-induced inflammation and nuclear architecture. Mech Ageing Dev 2016; 165:17-26. [PMID: 27702596 DOI: 10.1016/j.mad.2016.09.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 09/20/2016] [Accepted: 09/25/2016] [Indexed: 12/12/2022]
Abstract
Nuclear architecture and the chromatin state affect most-if not all- DNA-dependent transactions, including the ability of cells to sense DNA lesions and restore damaged DNA back to its native form. Recent evidence points to functional links between DNA damage sensors, DNA repair mechanisms and the innate immune responses. The latter raises the question of how such seemingly disparate processes operate within the intrinsically complex nuclear landscape and the chromatin environment. Here, we discuss how DNA damage-induced immune responses operate within chromatin and the distinct sub-nuclear compartments highlighting their relevance to chronic inflammation.
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Affiliation(s)
- Kalliopi Stratigi
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013, Heraklion, Crete, Greece
| | - Ourania Chatzidoukaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013, Heraklion, Crete, Greece
| | - George A Garinis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, 70013, Heraklion, Crete, Greece; Department of Biology, University of Crete, Vassilika Vouton, GR71409, Heraklion, Crete, Greece.
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16
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Krawiec P, Mełges B, Pac-Kożuchowska E, Mroczkowska-Juchkiewicz A, Czerska K. Fitting the pieces of the puzzle together: a case report of the Dunnigan-type of familial partial lipodystrophy in the adolescent girl. BMC Pediatr 2016; 16:38. [PMID: 26976018 PMCID: PMC4790055 DOI: 10.1186/s12887-016-0581-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 03/12/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Familial partial lipodystrophy of the Dunnigan type (FPLD 2) is a rare autosomal dominant disorder caused by the mutations of the lamin A/C gene leading to the defective adipogenesis, premature death of adipocytes and lipotoxicity. FPLD 2 is characterized by a progressive loss of subcutaneous adipose tissue in the limbs and trunk, and accumulation of body fat in the face and neck with accompanying severe metabolic derangements including insulin resistance, glucose intolerance, diabetes, dyslipidemia, steatohepatitis. Clinical presentation of FPLD 2 can often lead to misdiagnosis with metabolic syndrome, type 2 diabetes or Cushing syndrome. CASE PRESENTATION We report a case of a 14-year-old girl admitted to the Department of Paediatrics due to chronic hypertransaminasemia. On physical examination the girl appeared to have athletic posture. She demonstrated the absence of subcutaneous adipose tissue in the extremities, sparing the face, neck and gluteal area, pseudo-hypertrophy of calves, prominent peripheral veins of limbs, massive acanthosis nigricans around the neck, in axillary and inguinal regions and natural skin folds, hepatosplenomegaly. Laboratory results revealed hypertransaminasemia, elevated γ-glutamyltranspeptydase, and dyslipidemia, hyperinsulinaemia with insulin resistance, impaired glucose tolerance, and hyperuricemia. Diffuse steatoheptitis in the liver biopsy was stated. Clinical suspicion of FPLD 2 was confirmed genetically. The pathogenic mutation, R482W (p.Arg482Trp), responsible for the FPLD 2 phenotype was identified in one allele of the LMNA gene. CONCLUSIONS Presented case highlights the importance of the holistic approach to a patient and the need of accomplished collaboration between paediatricians and geneticists. FPLD 2 should be considered in the differential diagnosis of diabetes, dyslipidemia, steatohepatitis, acanthosis nigricans and polycystic ovary syndrome.
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Affiliation(s)
- Paulina Krawiec
- Department of Paediatrics, Medical University of Lublin, Racławickie 1, 20-059, Lublin, Poland.
| | - Beata Mełges
- Department of Paediatrics, Medical University of Lublin, Racławickie 1, 20-059, Lublin, Poland
| | | | | | - Kamila Czerska
- MEDGEN Medical Center, Orzycka 27, 02-695, Warsaw, Poland
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17
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Wang J, Cai J, Huang Y, Ke Q, Wu B, Wang S, Han X, Wang T, Wang Y, Li W, Lao C, Song W, Xiang AP. Nestin regulates proliferation and invasion of gastrointestinal stromal tumor cells by altering mitochondrial dynamics. Oncogene 2015; 35:3139-50. [PMID: 26434586 DOI: 10.1038/onc.2015.370] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Revised: 08/21/2015] [Accepted: 08/28/2015] [Indexed: 12/11/2022]
Abstract
Nestin is widely expressed in numerous tumors and has become a diagnostic and prognostic indicator. However, the exact mechanism by which nestin contributes to tumor malignancy remains poorly understood. Here, we found marked upregulation of nestin expression in highly proliferative and invasive gastrointestinal stromal tumor (GIST) specimens. Nestin knockdown in GIST cells reduced the proliferative and invasive activity owing to a decrease of mitochondrial intracellular reactive oxygen species (ROS) generation. Furthermore, nestin was co-localized with mitochondria, and knockdown of nestin increased mitochondrial elongation and influenced the mitochondrial function, including oxygen consumption rates, ATP generation and mitochondrial membrane potential and so on. In exploring the underlying mechanism, we demonstrated nestin knockdown inhibited the mitochondrial recruitment of Dynamin-related protein1 and induced the change of mitochondrial dynamics. Thus, nestin may have an important role in GIST malignancy by regulating mitochondrial dynamics and altering intracellular ROS levels. The findings provide new clues to reveal mechanisms by which nestin mediates the proliferation and invasion of GISTs.
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Affiliation(s)
- J Wang
- Program of Stem Cells and Regenerative Medicine, Affiliated Guangzhou Women and Children's Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - J Cai
- Program of Stem Cells and Regenerative Medicine, Affiliated Guangzhou Women and Children's Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China.,Biotherapy Center, Third Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Y Huang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Q Ke
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China.,Department of Cell Biology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - B Wu
- Department of Cardiology, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - S Wang
- Department of Gastrointestinal-Pancreatic Surgery, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - X Han
- Department of Population Genetics and Prevention, Fuwai Hospital of Peking Union Medical College, Beijing, China
| | - T Wang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Y Wang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - W Li
- Program of Stem Cells and Regenerative Medicine, Affiliated Guangzhou Women and Children's Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China.,Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - C Lao
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - W Song
- Department of Gastrointestinal-Pancreatic Surgery, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - A P Xiang
- Program of Stem Cells and Regenerative Medicine, Affiliated Guangzhou Women and Children's Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China.,Biotherapy Center, Third Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Department of Biochemistry, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
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18
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Myopathic lamin mutations cause reductive stress and activate the nrf2/keap-1 pathway. PLoS Genet 2015; 11:e1005231. [PMID: 25996830 PMCID: PMC4440730 DOI: 10.1371/journal.pgen.1005231] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 04/20/2015] [Indexed: 12/29/2022] Open
Abstract
Mutations in the human LMNA gene cause muscular dystrophy by mechanisms that are incompletely understood. The LMNA gene encodes A-type lamins, intermediate filaments that form a network underlying the inner nuclear membrane, providing structural support for the nucleus and organizing the genome. To better understand the pathogenesis caused by mutant lamins, we performed a structural and functional analysis on LMNA missense mutations identified in muscular dystrophy patients. These mutations perturb the tertiary structure of the conserved A-type lamin Ig-fold domain. To identify the effects of these structural perturbations on lamin function, we modeled these mutations in Drosophila Lamin C and expressed the mutant lamins in muscle. We found that the structural perturbations had minimal dominant effects on nuclear stiffness, suggesting that the muscle pathology was not accompanied by major structural disruption of the peripheral nuclear lamina. However, subtle alterations in the lamina network and subnuclear reorganization of lamins remain possible. Affected muscles had cytoplasmic aggregation of lamins and additional nuclear envelope proteins. Transcription profiling revealed upregulation of many Nrf2 target genes. Nrf2 is normally sequestered in the cytoplasm by Keap-1. Under oxidative stress Nrf2 dissociates from Keap-1, translocates into the nucleus, and activates gene expression. Unexpectedly, biochemical analyses revealed high levels of reducing agents, indicative of reductive stress. The accumulation of cytoplasmic lamin aggregates correlated with elevated levels of the autophagy adaptor p62/SQSTM1, which also binds Keap-1, abrogating Nrf2 cytoplasmic sequestration, allowing Nrf2 nuclear translocation and target gene activation. Elevated p62/SQSTM1 and nuclear enrichment of Nrf2 were identified in muscle biopsies from the corresponding muscular dystrophy patients, validating the disease relevance of our Drosophila model. Thus, novel connections were made between mutant lamins and the Nrf2 signaling pathway, suggesting new avenues of therapeutic intervention that include regulation of protein folding and metabolism, as well as maintenance of redox homoeostasis.
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19
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Gay S, Foiani M. Nuclear envelope and chromatin, lock and key of genome integrity. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:267-330. [PMID: 26008788 DOI: 10.1016/bs.ircmb.2015.03.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
More than as an inert separation between the inside and outside of the nucleus, the nuclear envelope (NE) constitutes an active toll, which controls the import and export of molecules, and also a hub for a diversity of genomic processes, such as transcription, DNA repair, and chromatin dynamics. Proteins localized at the inner surface of the NE (such as lamins, nuclear pore proteins, lamin-associated proteins) interact with chromatin in a dynamic manner, contributing to the establishment of topological domains. In this review, we address the complex interplay between chromatin and NE. We discuss the divergence of this cross talk during evolution and comment both on the current established models and the most recent findings. In particular, we focus our attention on how the NE cooperates with chromatin in protecting the genome integrity.
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Affiliation(s)
- Sophie Gay
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy
| | - Marco Foiani
- IFOM, the FIRC Institute of Molecular Oncology, Milan, Italy; Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Milan, Italy
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20
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New look at the role of progerin in skin aging. MENOPAUSE REVIEW 2015; 14:53-8. [PMID: 26327889 PMCID: PMC4440198 DOI: 10.5114/pm.2015.49532] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 11/29/2014] [Accepted: 12/02/2014] [Indexed: 11/30/2022]
Abstract
Current literature data indicate that progerin, which is a mutant of lamin A, may be one of several previously known physiological biomarkers of the aging process which begins at the age of 30. Lamins belong to the family of intermediate filaments type V and are an important component of the nuclear envelope (NE). The physiological processes of an alternative splicing of LMNA (lamin A/C) gene and posttranslational processing result in the formation of different variants of this gene. Prelamin A is generated in cytosol and modified by respective enzymes. In the final step, 15-aa peptide is released at the C-terminus, resulting in mature lamin A. Point mutation of cytosine to thymine at position 1824 in exon 11 of LMNA gene causes a truncated form of lamin A, which is defined as progerin. In the course of time, progerin is mainly found in skin fibroblasts and reticular layers of terminally differentiated keratinocytes. Changes take place in the nucleus and they are similar to those observed in patients with Hutchinson-Gilford progeria syndrome and refer mainly to an increase in the amount of reactive oxygen species which reduce the level of antioxidant enzymes, DNA damage and histone modification. There are still pending studies on working out new anti-aging strategies and the skin is the main area of research. Biomimetic peptides (analogues of elafin) are used in cosmetics to reduce the formation of progerin.
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21
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Der Perng M, Quinlan RA. The Dynamic Duo of Small Heat Proteins and IFs Maintain Cell Homeostasis, Resist Cellular Stress and Enable Evolution in Cells and Tissues. HEAT SHOCK PROTEINS 2015. [DOI: 10.1007/978-3-319-16077-1_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Nuclear envelope-related lipodystrophies. Semin Cell Dev Biol 2014; 29:148-57. [DOI: 10.1016/j.semcdb.2013.12.015] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/06/2013] [Accepted: 12/20/2013] [Indexed: 12/12/2022]
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23
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Shimi T, Goldman RD. Nuclear lamins and oxidative stress in cell proliferation and longevity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 773:415-30. [PMID: 24563359 DOI: 10.1007/978-1-4899-8032-8_19] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In mammalian cells, the nuclear lamina is composed of a complex fibrillar network associated with the inner membrane of the nuclear envelope. The lamina provides mechanical support for the nucleus and functions as the major determinant of its size and shape. At its innermost aspect it associates with peripheral components of chromatin and thereby contributes to the organization of interphase chromosomes. The A- and B-type lamins are the major structural components of the lamina, and numerous mutations in the A-type lamin gene have been shown to cause many types of human diseases collectively known as the laminopathies. These mutations have also been shown to cause a disruption in the normal interactions between the A and B lamin networks. The impact of these mutations on nuclear functions is related to the roles of lamins in regulating various essential processes including DNA synthesis and damage repair, transcription and the regulation of genes involved in the response to oxidative stress. The major cause of oxidative stress is the production of reactive oxygen species (ROS), which is critically important for cell proliferation and longevity. Moderate increases in ROS act to initiate signaling pathways involved in cell proliferation and differentiation, whereas excessive increases in ROS cause oxidative stress, which in turn induces cell death and/or senescence. In this review, we cover current findings about the role of lamins in regulating cell proliferation and longevity through oxidative stress responses and ROS signaling pathways. We also speculate on the involvement of lamins in tumor cell proliferation through the control of ROS metabolism.
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Affiliation(s)
- Takeshi Shimi
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Ward Building 11-145 303 E, Chicago Avenue, Chicago, IL, 60611-3008, USA,
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24
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Scharner J, Lu HC, Fraternali F, Ellis JA, Zammit PS. Mapping disease-related missense mutations in the immunoglobulin-like fold domain of lamin A/C reveals novel genotype-phenotype associations for laminopathies. Proteins 2013; 82:904-15. [DOI: 10.1002/prot.24465] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 10/11/2013] [Accepted: 10/21/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Juergen Scharner
- Randall Division of Cell and Molecular Biophysics; King's College London; London SE1 1UL United Kingdom
| | - Hui-Chun Lu
- Randall Division of Cell and Molecular Biophysics; King's College London; London SE1 1UL United Kingdom
| | - Franca Fraternali
- Randall Division of Cell and Molecular Biophysics; King's College London; London SE1 1UL United Kingdom
| | - Juliet A. Ellis
- Randall Division of Cell and Molecular Biophysics; King's College London; London SE1 1UL United Kingdom
| | - Peter S. Zammit
- Randall Division of Cell and Molecular Biophysics; King's College London; London SE1 1UL United Kingdom
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25
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Houben F, De Vos WH, Krapels IPC, Coorens M, Kierkels GJJ, Kamps MAF, Verstraeten VLRM, Marcelis CLM, van den Wijngaard A, Ramaekers FCS, Broers JLV. Cytoplasmic localization of PML particles in laminopathies. Histochem Cell Biol 2012; 139:119-34. [PMID: 22918509 DOI: 10.1007/s00418-012-1005-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/23/2012] [Indexed: 01/01/2023]
Abstract
There is growing evidence that laminopathies, diseases associated with mutations in the LMNA gene, are caused by a combination of mechanical and gene regulatory distortions. Strikingly, there is a large variability in disease symptoms between individual patients carrying an identical LMNA mutation. This is why classical genetic screens for mutations appear to have limited predictive value for disease development. Recently, the widespread occurrence of repetitive nuclear ruptures has been described in fibroblast cultures from various laminopathy patients. Since this phenomenon was strongly correlated with disease severity, the identification of biomarkers that report on these rupture events could have diagnostic relevance. One such candidate marker is the PML nuclear body, a structure that is normally confined to the nuclear interior, but leaks out of the nucleus upon nuclear rupture. Here, we show that a variety of laminopathies shows the presence of these cytoplasmic PML particles (PML CPs), and that the amount of these protein aggregates increases with severity of the disease. In addition, between clinically healthy individuals, carrying LMNA mutations, significant differences can be found. Therefore, we postulate that detection of PML CPs in patient fibroblasts could become a valuable marker for diagnosis of disease development.
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Affiliation(s)
- F Houben
- Department of Molecular Cell Biology, CARIM, School for Cardiovascular Diseases, Maastricht University Medical Center, UNS50 Box 17, P.O. Box 616, NL-6200 MD, Maastricht, The Netherlands
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Sieprath T, Darwiche R, De Vos WH. Lamins as mediators of oxidative stress. Biochem Biophys Res Commun 2012; 421:635-9. [PMID: 22538370 DOI: 10.1016/j.bbrc.2012.04.058] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 04/10/2012] [Indexed: 01/29/2023]
Abstract
The nuclear lamina defines both structural and functional properties of the eukaryotic cell nucleus. Mutations in the LMNA gene, encoding A-type lamins, lead to a broad spectrum of diseases termed laminopathies. While different hypotheses have been postulated to explain disease development, there is still no unified view on the mechanistic basis of laminopathies. Recent observations indicate that laminopathies are often accompanied by altered levels of reactive oxygen species and a higher susceptibility to oxidative stress at the cellular level. In this review, we highlight the role of reactive oxygen species for cell function and disease development in the context of laminopathies and present a framework of non-exclusive mechanisms to explain the reciprocal interactions between a dysfunctional lamina and altered redox homeostasis.
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Affiliation(s)
- Tom Sieprath
- Cell Systems and Cellular Imaging Group, Department of Molecular Biotechnology, Ghent University, Ghent, Belgium
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Abstract
The nuclear envelope is not only important for the structural integrity of the nucleus, but also involved in a number of cellular functions. It has been shown to be important for maintaining and controlling chromatin organization, sequestering transcription factors, replication, transcription and signalling. The nuclear envelope is thus important for development and differentiation, and some of its components are essential for cell viability. Among the many functions which are emerging for the nuclear envelope is its involvement in protecting the cell against different types of cellular stress. In the present paper, we review key findings which describe the roles of nuclear envelope components in responses to common types of stress conditions.
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Inner nuclear membrane proteins: impact on human disease. Chromosoma 2012; 121:153-67. [DOI: 10.1007/s00412-012-0360-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/02/2012] [Accepted: 01/03/2012] [Indexed: 02/01/2023]
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Magagnotti C, Bachi A, Zerbini G, Fattore E, Fermo I, Riba M, Previtali SC, Ferrari M, Andolfo A, Benedetti S. Protein profiling reveals energy metabolism and cytoskeletal protein alterations in LMNA mutation carriers. Biochim Biophys Acta Mol Basis Dis 2012; 1822:970-9. [PMID: 22326558 DOI: 10.1016/j.bbadis.2012.01.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 12/21/2011] [Accepted: 01/27/2012] [Indexed: 12/11/2022]
Abstract
Nuclear envelope-related muscular dystrophies, in particular those referred to as laminopathies, are relatively novel and unclear diseases, also considering the increasing number of mutations identified so far in genes of the nuclear envelope. As regard LMNA gene, only tentative relations between phenotype, type and localization of the mutations have been established in striated muscle diseases, while laminopathies affecting adipose tissue, peripheral nerves or progerioid syndromes could be linked to specific genetic variants. This study describes the biochemical phenotype of neuromuscular laminopathies in samples derived from LMNA mutant patients. Since it has been reported that nuclear alterations, due to LMNA defects, are present also in fibroblasts from Emery-Dreifuss muscular dystrophy and familial partial lipodystrophy patients, we analyzed 2D-maps of skin fibroblasts of patients carrying 12 different LMNA mutations spread along the entire gene. To recognize distinctive proteins underlying affected biochemical pathways, we compared them with fibroblasts from healthy controls and, more importantly, fibroblasts from patients with non-lamin related neuromuscular disorders. We found less abundance of cytoskeletal/structural proteins, confirming a dominant role for Lamin A/C in structural support of nuclear architecture. Interestingly, we also established significant changes in the expression of proteins involved in cellular energy production and oxidative stress response. To our knowledge, this is the first report where proteomics was applied to characterize ex-vivo cells from LMNA patients, suggesting that this may represent a new approach to better understand the molecular mechanisms of these rare diseases and facilitate the development of novel therapeutic treatments.
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Affiliation(s)
- Cinzia Magagnotti
- ProMiFa, Protein Microsequencing Facility, Division of Cell Biology and Genetics, San Raffaele Scientific Institute, Milan, Italy
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Abstract
Progeroid laminopathies are characterized by the abnormal processing of lamin A, the appearance of misshapen nuclei, and the accumulation and persistence of DNA damage. In the present article, I consider the contribution of defective DNA damage pathways to the pathology of progeroid laminopathies. Defects in DNA repair pathways appear to be caused by a combination of factors. These include abnormal epigenetic modifications of chromatin that are required to recruit DNA repair pathways to sites of DNA damage, abnormal recruitment of DNA excision repair proteins to sites of DNA double-strand breaks, and unrepairable ROS (reactive oxygen species)-induced DNA damage. At least two of these defective processes offer the potential for novel therapeutic approaches.
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Saini-Chohan HK, Mitchell RW, Vaz FM, Zelinski T, Hatch GM. Delineating the role of alterations in lipid metabolism to the pathogenesis of inherited skeletal and cardiac muscle disorders: Thematic Review Series: Genetics of Human Lipid Diseases. J Lipid Res 2011; 53:4-27. [PMID: 22065858 DOI: 10.1194/jlr.r012120] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
As the specific composition of lipids is essential for the maintenance of membrane integrity, enzyme function, ion channels, and membrane receptors, an alteration in lipid composition or metabolism may be one of the crucial changes occurring during skeletal and cardiac myopathies. Although the inheritance (autosomal dominant, autosomal recessive, and X-linked traits) and underlying/defining mutations causing these myopathies are known, the contribution of lipid homeostasis in the progression of these diseases needs to be established. The purpose of this review is to present the current knowledge relating to lipid changes in inherited skeletal muscle disorders, such as Duchenne/Becker muscular dystrophy, myotonic muscular dystrophy, limb-girdle myopathic dystrophies, desminopathies, rostrocaudal muscular dystrophy, and Dunnigan-type familial lipodystrophy. The lipid modifications in familial hypertrophic and dilated cardiomyopathies, as well as Barth syndrome and several other cardiac disorders associated with abnormal lipid storage, are discussed. Information on lipid alterations occurring in these myopathies will aid in the design of improved methods of screening and therapy in children and young adults with or without a family history of genetic diseases.
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Affiliation(s)
- Harjot K Saini-Chohan
- Department of Pharmacology and Therapeutics, Academic Medical Center, Amsterdam, The Netherlands
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De Vos WH, Houben F, Kamps M, Malhas A, Verheyen F, Cox J, Manders EMM, Verstraeten VLRM, van Steensel MAM, Marcelis CLM, van den Wijngaard A, Vaux DJ, Ramaekers FCS, Broers JLV. Repetitive disruptions of the nuclear envelope invoke temporary loss of cellular compartmentalization in laminopathies. Hum Mol Genet 2011; 20:4175-86. [PMID: 21831885 DOI: 10.1093/hmg/ddr344] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The nuclear lamina provides structural support to the nucleus and has a central role in nuclear organization and gene regulation. Defects in its constituents, the lamins, lead to a class of genetic diseases collectively referred to as laminopathies. Using live cell imaging, we observed the occurrence of intermittent, non-lethal ruptures of the nuclear envelope in dermal fibroblast cultures of patients with different mutations of lamin A/C. These ruptures, which were absent in normal fibroblasts, could be mimicked by selective knockdown as well as knockout of LMNA and were accompanied by the loss of cellular compartmentalization. This was demonstrated by the influx of cytoplasmic transcription factor RelA and regulatory protein Cyclin B1 into the nucleus, and efflux of nuclear transcription factor OCT1 and nuclear structures containing the promyelocytic leukemia (PML) tumour suppressor protein to the cytoplasm. While recovery of enhanced yellow fluorescent protein-tagged nuclear localization signal in the nucleus demonstrated restoration of nuclear membrane integrity, part of the mobile PML structures became permanently translocated to the cytoplasm. These satellite PML structures were devoid of the typical PML body components, such as DAXX, SP100 or SUMO1. Our data suggest that nuclear rupture and loss of compartmentalization may add to cellular dysfunction and disease development in various laminopathies.
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Affiliation(s)
- Winnok H De Vos
- Department of Molecular Cell Biology, CARIM-School for Cardiovascular Diseases, Maastricht University Medical Center, PO Box 616, NL-6200 MD Maastricht, The Netherlands
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Richards SA, Muter J, Ritchie P, Lattanzi G, Hutchison CJ. The accumulation of un-repairable DNA damage in laminopathy progeria fibroblasts is caused by ROS generation and is prevented by treatment with N-acetyl cysteine. Hum Mol Genet 2011; 20:3997-4004. [PMID: 21807766 DOI: 10.1093/hmg/ddr327] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Fibroblasts from patients with the severe laminopathy diseases, restrictive dermopathy (RD) and Hutchinson Gilford progeria syndrome (HGPS), are characterized by poor growth in culture, the presence of abnormally shaped nuclei and the accumulation of DNA double-strand breaks (DSB). Here we show that the accumulation of DSB and poor growth of the fibroblasts but not the presence of abnormally shaped nuclei are caused by elevated levels of reactive oxygen species (ROS) and greater sensitivity to oxidative stress. Basal levels of ROS and sensitivity to H(2)O(2) were compared in fibroblasts from normal, RD and HGPS individuals using fluorescence activated cell sorting-based assays. Basal levels of ROS and stimulated levels of ROS were both 5-fold higher in the progeria fibroblasts. Elevated levels of ROS were correlated with lower proliferation indices but not with the presence of abnormally shaped nuclei. DSB induced by etoposide were repaired efficiently in normal, RD and HGPS fibroblasts. In contrast, DSB induced by ROS were repaired efficiently in normal fibroblasts, but in RD and HGPS fibroblasts many ROS-induced DSB were un-repairable. The accumulation of ROS-induced DSB appeared to cause the poor growth of RD and HGPS fibroblasts, since culture in the presence of the ROS scavenger N-acetyl cysteine (NAC) reduced the basal levels of DSB, eliminated un-repairable ROS-induced DSB and greatly improved population-doubling times. Our findings suggest that un-repaired ROS-induced DSB contribute significantly to the RD and HGPS phenotypes and that inclusion of NAC in a combinatorial therapy might prove beneficial to HGPS patients.
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Affiliation(s)
- Shane A Richards
- The School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE,UK
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Scharner J, Brown CA, Bower M, Iannaccone ST, Khatri IA, Escolar D, Gordon E, Felice K, Crowe CA, Grosmann C, Meriggioli MN, Asamoah A, Gordon O, Gnocchi VF, Ellis JA, Mendell JR, Zammit PS. Novel LMNA mutations in patients with Emery-Dreifuss muscular dystrophy and functional characterization of four LMNA mutations. Hum Mutat 2011; 32:152-67. [PMID: 20848652 DOI: 10.1002/humu.21361] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2010] [Accepted: 09/01/2010] [Indexed: 12/20/2022]
Abstract
Mutations in LMNA cause a variety of diseases affecting striated muscle including autosomal Emery-Dreifuss muscular dystrophy (EDMD), LMNA-associated congenital muscular dystrophy (L-CMD), and limb-girdle muscular dystrophy type 1B (LGMD1B). Here, we describe novel and recurrent LMNA mutations identified in 50 patients from the United States and Canada, which is the first report of the distribution of LMNA mutations from a large cohort outside Europe. This augments the number of LMNA mutations known to cause EDMD by 16.5%, equating to an increase of 5.9% in the total known LMNA mutations. Eight patients presented with either p.R249W/Q or p.E358K mutations and an early onset EDMD phenotype: two mutations recently associated with L-CMD. Importantly, 15 mutations are novel and include eight missense mutations (p.R189P, p.F206L, p.S268P, p.S295P, p.E361K, p.G449D, p.L454P, and p.W467R), three splice site mutations (c.IVS4 + 1G>A, c.IVS6 - 2A>G, and c.IVS8 + 1G>A), one duplication/in frame insertion (p.R190dup), one deletion (p.Q355del), and two silent mutations (p.R119R and p.K270K). Analysis of 4 of our lamin A mutations showed that some caused nuclear deformations and lamin B redistribution in a mutation specific manner. Together, this study significantly augments the number of EDMD patients on the database and describes 15 novel mutations that underlie EDMD, which will contribute to establishing genotype-phenotype correlations.
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Affiliation(s)
- Juergen Scharner
- Randall Division of Cell and Molecular Biophysics, King's College London, United Kingdom
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Intermediate filaments take the heat as stress proteins. Trends Cell Biol 2010; 20:79-91. [PMID: 20045331 DOI: 10.1016/j.tcb.2009.11.004] [Citation(s) in RCA: 190] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 11/13/2009] [Accepted: 11/17/2009] [Indexed: 11/18/2022]
Abstract
Intermediate filament (IF) proteins and heat shock proteins (HSPs) are large multimember families that share several features, including protein abundance, significant upregulation in response to a variety of stresses, cytoprotective functions, and the phenocopying of several human diseases after IF protein or HSP mutation. We are now coming to understand that these common elements point to IFs as important cellular stress proteins with some roles akin to those already well-characterized for HSPs. Unique functional roles for IFs include protection from mechanical stress, whereas HSPs are characteristically involved in protein folding and as chaperones. Shared IF and HSP cytoprotective roles include inhibition of apoptosis, organelle homeostasis, and scaffolding. In this report, we review data that corroborate the view that IFs function as highly specialized cytoskeletal stress proteins that promote cellular organization and homeostasis.
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