201
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Krishnamoorthy V, Khanna R, Parnaik VK. E3 ubiquitin ligase HECW2 targets PCNA and lamin B1. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2018; 1865:1088-1104. [PMID: 29753763 DOI: 10.1016/j.bbamcr.2018.05.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 04/20/2018] [Accepted: 05/07/2018] [Indexed: 12/21/2022]
Abstract
Lamins constitute the major architectural proteins of the nuclear lamina that help in maintaining nuclear organization. Mutations in lamins are associated with diverse degenerative diseases, collectively termed laminopathies. HECW2, a HECT-type E3 ubiquitin ligase, is transcriptionally upregulated in HeLa cells expressing Emery-Dreifuss muscular dystrophy-causing-lamin A mutants. However, the role of HECW2 upregulation in mediating downstream effects in lamin mutant-expressing cells was previously unexplored. Here, we show that HECW2 interacts with two lamin A-binding proteins, proliferating cell nuclear antigen (PCNA), via a canonical PCNA-interacting protein (PIP) motif, and lamin B1. HECW2 mediates their ubiquitination and targets them for proteasomal degradation. Cells expressing lamin A mutants G232E and Q294P, in which HECW2 is upregulated, show increased proteasomal degradation of PCNA and lamin B1 most likely mediated by HECW2. Our findings establish HECW2 as an E3 ubiquitin ligase for PCNA and lamin B1 which regulates their levels in laminopathic cells. We also found that HECW2 interacts with wild-type lamin A and ubiquitinates it and this interaction is reduced in case of lamin mutants G232E and Q294P. Our findings suggest that interplay among HECW2, lamin A, PCNA, and lamin B1 determines their respective homeostatic levels in the cell and dysregulation of these interactions may contribute to the pathogenicity of laminopathies.
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Affiliation(s)
| | - Richa Khanna
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - Veena K Parnaik
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India.
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202
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Spanu F, Saba L. Obesity and pericallosal lipoma in X-linked emery-dreifuss muscular dystrophy: A case report - Does Emerin play a role in adipocyte differentiation? World J Radiol 2018; 10:78-82. [PMID: 30079154 PMCID: PMC6068725 DOI: 10.4329/wjr.v10.i7.78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 06/11/2018] [Accepted: 06/28/2018] [Indexed: 02/06/2023] Open
Abstract
Emery dreifuss muscular dystrophy (EDMD) is a rare genetic syndrome consisting of tendon retractions, progressive muscle atrophy and cardiac involvement. We report a case of an obese patient affected by the familial X-linked form in which a pericallosal lipoma was found during investigation for a suspected acute vasculopathy. To date, EDMD has never been associated with cerebral lipomas and the X-linked form was never considered to be involved in lipodystrophic syndromes or non-muscular conditions. Our case confirms the variable expressivity of the disease and suggests a possible role of Emerin in the intranuclear regulation of signals for adipocyte cell differentiation.
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Affiliation(s)
- Fabio Spanu
- Department of Radiology, Azienda Ospedaliero Universitaria, Cagliari 09045, Italy
| | - Luca Saba
- Department of Radiology, Azienda Ospedaliero Universitaria, Cagliari 09045, Italy
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203
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Assessment of the Aging of the Brown Adipose Tissue by 18F-FDG PET/CT Imaging in the Progeria Mouse Model Lmna -/. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:8327089. [PMID: 30116163 PMCID: PMC6079616 DOI: 10.1155/2018/8327089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/09/2018] [Accepted: 04/24/2018] [Indexed: 01/16/2023]
Abstract
Brown adipose tissue (BAT) is an important energy metabolic organ that is highly implicated in obesity, type 2 diabetes, and atherosclerosis. Aging is one of the most important determinants of BAT activity. In this study, we used 18F-FDG PET/CT imaging to assess BAT aging in Lmna−/− mice. The maximum standardized uptake value (SUVMax) of the BAT was measured, and the target/nontarget (T/NT) values of BAT were calculated. The transcription and the protein expression levels of the uncoupling protein 1 (UCP1), beta3-adrenergic receptor (β3-AR), and the PR domain-containing 16 (PRDM16) were measured by quantitative real-time polymerase chain reaction (RT-PCR) and Western blotting or immunohistochemical analysis. Apoptosis and cell senescence rates in the BAT of WT and Lmna−/− mice were determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and by CDKN2A/p16INK4a immunohistochemical staining, respectively. At 14 weeks of age, the BAT SUVMax and the expression levels of UCP1, β3-AR, and PRDM16 in Lmna−/− mice were significantly reduced relative to WT mice. At the same time, the number of p16INK4a and TUNEL positively stained cells (%) increased in Lmna−/− mice. Collectively, our results indicate that the aging characteristics and the aging regulatory mechanism in the BAT of Lmna−/− mice can mimic the normal BAT aging process.
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204
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Martino F, Perestrelo AR, Vinarský V, Pagliari S, Forte G. Cellular Mechanotransduction: From Tension to Function. Front Physiol 2018; 9:824. [PMID: 30026699 PMCID: PMC6041413 DOI: 10.3389/fphys.2018.00824] [Citation(s) in RCA: 540] [Impact Index Per Article: 90.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/12/2018] [Indexed: 12/15/2022] Open
Abstract
Living cells are constantly exposed to mechanical stimuli arising from the surrounding extracellular matrix (ECM) or from neighboring cells. The intracellular molecular processes through which such physical cues are transformed into a biological response are collectively dubbed as mechanotransduction and are of fundamental importance to help the cell timely adapt to the continuous dynamic modifications of the microenvironment. Local changes in ECM composition and mechanics are driven by a feed forward interplay between the cell and the matrix itself, with the first depositing ECM proteins that in turn will impact on the surrounding cells. As such, these changes occur regularly during tissue development and are a hallmark of the pathologies of aging. Only lately, though, the importance of mechanical cues in controlling cell function (e.g., proliferation, differentiation, migration) has been acknowledged. Here we provide a critical review of the recent insights into the molecular basis of cellular mechanotransduction, by analyzing how mechanical stimuli get transformed into a given biological response through the activation of a peculiar genetic program. Specifically, by recapitulating the processes involved in the interpretation of ECM remodeling by Focal Adhesions at cell-matrix interphase, we revise the role of cytoskeleton tension as the second messenger of the mechanotransduction process and the action of mechano-responsive shuttling proteins converging on stage and cell-specific transcription factors. Finally, we give few paradigmatic examples highlighting the emerging role of malfunctions in cell mechanosensing apparatus in the onset and progression of pathologies.
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Affiliation(s)
- Fabiana Martino
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
| | - Ana R. Perestrelo
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
| | - Vladimír Vinarský
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
| | - Stefania Pagliari
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
| | - Giancarlo Forte
- Center for Translational Medicine, International Clinical Research Center, St. Anne’s University Hospital, Brno, Czechia
- Competence Center for Mechanobiology in Regenerative Medicine, INTERREG ATCZ133, Brno, Czechia
- Department of Biomaterials Science, Institute of Dentistry, University of Turku, Turku, Finland
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205
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Linker of nucleoskeleton and cytoskeleton complex proteins in cardiomyopathy. Biophys Rev 2018; 10:1033-1051. [PMID: 29869195 PMCID: PMC6082319 DOI: 10.1007/s12551-018-0431-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 05/24/2018] [Indexed: 12/21/2022] Open
Abstract
The linker of nucleoskeleton and cytoskeleton (LINC) complex couples the nuclear lamina to the cytoskeleton. The LINC complex and its associated proteins play diverse roles in cells, ranging from genome organization, nuclear morphology, gene expression, to mechanical stability. The importance of a functional LINC complex is highlighted by the large number of mutations in genes encoding LINC complex proteins that lead to skeletal and cardiac myopathies. In this review, the structure, function, and interactions between components of the LINC complex will be described. Mutations that are known to cause cardiomyopathy in patients will be discussed alongside their respective mouse models. Furthermore, future challenges for the field and emerging technologies to investigate LINC complex function will be discussed.
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206
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Smith ER, George SH, Kobetz E, Xu XX. New biological research and understanding of Papanicolaou's test. Diagn Cytopathol 2018; 46:507-515. [PMID: 29663734 PMCID: PMC5949091 DOI: 10.1002/dc.23941] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 03/08/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023]
Abstract
The development of the Papanicolaou smear test by Dr. George Nicholas Papanicolaou (1883-1962) is one of the most significant achievements in screening for disease and cancer prevention in history. The Papanicolaou smear has been used for screening of cervical cancer since the 1950s. The test is technically straightforward and practical and based on a simple scientific observation: malignant cells have an aberrant nuclear morphology that can be distinguished from benign cells. Here, we review the scientific understanding that has been achieved and continues to be made on the causes and consequences of abnormal nuclear morphology, the basis of Dr. Papanicolaou's invention. The deformed nuclear shape is caused by the loss of lamina and nuclear envelope structural proteins. The consequences of a nuclear envelope defect include chromosomal numerical instability, altered chromatin organization and gene expression, and increased cell mobility because of a malleable nuclear envelope. HPV (Human Papilloma Virus) infection is recognized as the key etiology in the development of cervical cancer. Persistent HPV infection causes disruption of the nuclear lamina, which presents as a change in nuclear morphology detectable by a Papanicolaou smear. Thus, the causes and consequences of nuclear deformation are now linked to the mechanisms of viral carcinogenesis, and are still undergoing active investigation to reveal the details. Recently a statue was installed in front of the Papanicolaou's Cancer Research Building to honor the inventor. Remarkably, the invention nearly 60 years ago by Dr. Papanicolaou still exerts clinical impacts and inspires scientific inquiries.
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Affiliation(s)
- Elizabeth R. Smith
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Sophia H. George
- Department of Obstetrics & Gynecology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Erin Kobetz
- Department of Medicine, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
| | - Xiang-Xi Xu
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL 33136
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207
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Ankam S, Teo BKK, Pohan G, Ho SWL, Lim CK, Yim EKF. Temporal Changes in Nucleus Morphology, Lamin A/C and Histone Methylation During Nanotopography-Induced Neuronal Differentiation of Stem Cells. Front Bioeng Biotechnol 2018; 6:69. [PMID: 29904629 PMCID: PMC5990852 DOI: 10.3389/fbioe.2018.00069] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/09/2018] [Indexed: 01/14/2023] Open
Abstract
Stem cell differentiation can be regulated by biophysical cues such as nanotopography. It involves sensing and integration of these biophysical cues into their transcriptome with a mechanism that is yet to be discovered. In addition to the cytoskeletal and focal adhesion remodeling, nanotopography has also been shown to modulate nucleus morphology. Here, we studied the effect of nanotopography on the temporal changes in nuclei of human embryonic stem cells (hESCs) and human mesenchymal stem cells (hMSCs). Using a high throughput Multi-architecture (MARC) chip analysis, the circularity of the stem cell nuclei changed significantly on different patterns. Human ESCs and MSCs showed different temporal changes in nucleus morphology, lamin A/C expression and histone methylation during topography-induced neuronal differentiation. In hESCs, the expression of nuclear matrix protein, lamin A/C during neuronal differentiation of hESCs on PDMS samples were weakly detected in the first 7 days of differentiation. The histone 3 trimethylation on Lysine 9 (H3K9me3) decreased after differentiation initiated and showed temporal changes in their expression and organization during neuronal differentiation. In hMSCs, the expression of lamin A/C was significantly increased after the first 24 h of cell culture. The quantitative analysis of histone methylation also showed a significant increase in hMSCs histone methylation on 250 nm anisotropic nanogratings within the first 24 h of seeding. This reiterates the importance of cell-substrate sensing within the first 24 h for adult stem cells. The lamin A/C expression and histone methylation shows a correlation of epigenetic changes in early events of differentiation, giving an insight on how extracellular nanotopographical cues are transduced into nuclear biochemical signals. Collectively, these results provide more understanding into the nuclear regulation of the mechanotransduction of nanotopographical cues in stem cell differentiation.
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Affiliation(s)
- Soneela Ankam
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Benjamin K K Teo
- Mechanobiology Institute Singapore, National University of Singapore, Singapore, Singapore
| | - Grace Pohan
- Department of Chemical Engineering, University of Waterloo, Waterloo, ON, Canada
| | - Shawn W L Ho
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore
| | - Choon K Lim
- Mechanobiology Institute Singapore, National University of Singapore, Singapore, Singapore
| | - Evelyn K F Yim
- Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore.,Mechanobiology Institute Singapore, National University of Singapore, Singapore, Singapore.,Department of Chemical Engineering, University of Waterloo, Waterloo, ON, Canada.,Department of Surgery, National University of Singapore, Singapore, Singapore
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208
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Random Motion of Chromatin Is Influenced by Lamin A Interconnections. Biophys J 2018; 114:2465-2472. [PMID: 29759373 DOI: 10.1016/j.bpj.2018.04.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/11/2018] [Accepted: 04/19/2018] [Indexed: 01/30/2023] Open
Abstract
Using fluorescence correlation spectroscopy in single-plane illumination microscopy, we investigated the dynamics of chromatin in interphase mouse adult fibroblast cell nuclei under the influence of the intermediate filament protein lamin A. We find that 1) lamin A-eGFP and histone H2A-mRFP show significant comobility, indicating that their motions are clearly interconnected in the nucleus, and 2) that the random motion of histones H2A within the chromatin network is subdiffusive, i.e., the effective diffusion coefficient decreases for slow timescales. Knocking out lamin A changes the diffusion back to normal. Thus, lamin A influences the dynamics of the entire chromatin network. Our conclusion is that lamin A plays a central role in determining the viscoelasticity of the chromatin network and helping to maintain local ordering of interphase chromosomes.
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209
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Brady GF, Kwan R, Cunha JB, Elenbaas JS, Omary MB. Lamins and Lamin-Associated Proteins in Gastrointestinal Health and Disease. Gastroenterology 2018; 154:1602-1619.e1. [PMID: 29549040 PMCID: PMC6038707 DOI: 10.1053/j.gastro.2018.03.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/04/2018] [Accepted: 03/06/2018] [Indexed: 02/07/2023]
Abstract
The nuclear lamina is a multi-protein lattice composed of A- and B-type lamins and their associated proteins. This protein lattice associates with heterochromatin and integral inner nuclear membrane proteins, providing links among the genome, nucleoskeleton, and cytoskeleton. In the 1990s, mutations in EMD and LMNA were linked to Emery-Dreifuss muscular dystrophy. Since then, the number of diseases attributed to nuclear lamina defects, including laminopathies and other disorders, has increased to include more than 20 distinct genetic syndromes. Studies of patients and mouse genetic models have pointed to important roles for lamins and their associated proteins in the function of gastrointestinal organs, including liver and pancreas. We review the interactions and functions of the lamina in relation to the nuclear envelope and genome, the ways in which its dysfunction is thought to contribute to human disease, and possible avenues for targeted therapies.
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Affiliation(s)
- Graham F. Brady
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan,To whom correspondence should be addressed: University of Michigan Medical School, Division of Gastroenterology, Department of Internal Medicine, 1137 Catherine St., Ann Arbor, MI 48109-5622.
| | - Raymond Kwan
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Juliana Bragazzi Cunha
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Jared S. Elenbaas
- Medical Scientist Training Program, Washington University, St Louis, Missouri
| | - M. Bishr Omary
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan,Ǻbo Akademi University, Turku, Finland
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210
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Aberrant Compartment Formation by HSPB2 Mislocalizes Lamin A and Compromises Nuclear Integrity and Function. Cell Rep 2018; 20:2100-2115. [PMID: 28854361 PMCID: PMC5583511 DOI: 10.1016/j.celrep.2017.08.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/10/2017] [Accepted: 08/01/2017] [Indexed: 11/23/2022] Open
Abstract
Small heat shock proteins (HSPBs) contain intrinsically disordered regions (IDRs), but the functions of these IDRs are still unknown. Here, we report that, in mammalian cells, HSPB2 phase separates to form nuclear compartments with liquid-like properties. We show that phase separation requires the disordered C-terminal domain of HSPB2. We further demonstrate that, in differentiating myoblasts, nuclear HSPB2 compartments sequester lamin A. Increasing the nuclear concentration of HSPB2 causes the formation of aberrant nuclear compartments that mislocalize lamin A and chromatin, with detrimental consequences for nuclear function and integrity. Importantly, phase separation of HSPB2 is regulated by HSPB3, but this ability is lost in two identified HSPB3 mutants that are associated with myopathy. Our results suggest that HSPB2 phase separation is involved in reorganizing the nucleoplasm during myoblast differentiation. Furthermore, these findings support the idea that aberrant HSPB2 phase separation, due to HSPB3 loss-of-function mutations, contributes to myopathy. HSPB2 undergoes concentration-dependent liquid-liquid phase separation in cells HSPB2 phase separation requires its intrinsically disordered C-terminal tail Aberrant HSPB2 phase separation mislocalizes lamin A HSPB3, but not two HSPB3 myopathy mutants, inhibits HSPB2 phase separation
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211
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SMAD6 overexpression leads to accelerated myogenic differentiation of LMNA mutated cells. Sci Rep 2018; 8:5618. [PMID: 29618840 PMCID: PMC5884786 DOI: 10.1038/s41598-018-23918-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/22/2018] [Indexed: 12/23/2022] Open
Abstract
LMNA gene encodes lamins A and C, two major components of the nuclear lamina, a network of intermediate filaments underlying the inner nuclear membrane. Most of LMNA mutations are associated with cardiac and/or skeletal muscles defects. Muscle laminopathies include Emery-Dreifuss Muscular Dystrophy, Limb-Girdle Muscular Dystrophy 1B, LMNA-related Congenital Muscular Dystrophy and Dilated Cardiomyopathy with conduction defects. To identify potential alterations in signaling pathways regulating muscle differentiation in LMNA-mutated myoblasts, we used a previously described model of conditionally immortalized murine myoblasts: H-2K cell lines. Comparing gene expression profiles in wild-type and Lmna∆8–11 H-2K myoblasts, we identified two major alterations in the BMP (Bone Morphogenetic Protein) pathway: Bmp4 downregulation and Smad6 overexpression. We demonstrated that these impairments lead to Lmna∆8–11 myoblasts premature differentiation and can be rescued by downregulating Smad6 expression. Finally, we showed that BMP4 pathway defects are also present in myoblasts from human patients carrying different heterozygous LMNA mutations.
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212
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Ziat E, Mamchaoui K, Beuvin M, Nelson I, Azibani F, Spuler S, Bonne G, Bertrand AT. FHL1B Interacts with Lamin A/C and Emerin at the Nuclear Lamina and is Misregulated in Emery-Dreifuss Muscular Dystrophy. J Neuromuscul Dis 2018; 3:497-510. [PMID: 27911330 DOI: 10.3233/jnd-160169] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Emery-Dreifuss muscular dystrophy (EDMD) is associated with mutations in EMD and LMNA genes, encoding for the nuclear envelope proteins emerin and lamin A/C, indicating that EDMD is a nuclear envelope disease. We recently reported mutations in FHL1 gene in X-linked EDMD. FHL1 encodes FHL1A, and the two minor isoforms FHL1B and FHL1C. So far, none have been described at the nuclear envelope. OBJECTIVE To gain insight into the pathophysiology of EDMD, we focused our attention on the poorly characterized FHL1B isoform. METHODS The amount and the localisation of FHL1B were evaluated in control and diseased human primary myoblasts using immunofluorescence and western blotting. RESULTS We found that in addition to a cytoplasmic localization, this isoform strongly accumulated at the nuclear envelope of primary human myoblasts, like but independently of lamin A/C and emerin. During myoblast differentiation, we observed a major reduction of FHL1B protein expression, especially in the nucleus. Interestingly, we found elevated FHL1B expression level in myoblasts from an FHL1-related EDMD patient where the FHL1 mutation only affects FHL1A, as well as in myoblasts from an LMNA-related EDMD patient. CONCLUSIONS Altogether, the specific localization of FHL1B and its modulation in disease-patient's myoblasts confirmed FHL1-related EDMD as a nuclear envelope disease.
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Affiliation(s)
- Esma Ziat
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France.,Muscle Research Unit, Experimental and Clinical Research Center, A Joint Cooperation between Max-Delbrück-Center for Molecular Medicine and Charite Medical Faculty, Berlin, Germany
| | - Kamel Mamchaoui
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
| | - Maud Beuvin
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
| | - Isabelle Nelson
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
| | - Feriel Azibani
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
| | - Simone Spuler
- Muscle Research Unit, Experimental and Clinical Research Center, A Joint Cooperation between Max-Delbrück-Center for Molecular Medicine and Charite Medical Faculty, Berlin, Germany
| | - Gisèle Bonne
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
| | - Anne T Bertrand
- Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, F-75013 Paris, France
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213
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Emerging views of the nucleus as a cellular mechanosensor. Nat Cell Biol 2018; 20:373-381. [PMID: 29467443 DOI: 10.1038/s41556-018-0038-y] [Citation(s) in RCA: 336] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/09/2018] [Indexed: 12/14/2022]
Abstract
The ability of cells to respond to mechanical forces is critical for numerous biological processes. Emerging evidence indicates that external mechanical forces trigger changes in nuclear envelope structure and composition, chromatin organization and gene expression. However, it remains unclear if these processes originate in the nucleus or are downstream of cytoplasmic signals. Here we discuss recent findings that support a direct role of the nucleus in cellular mechanosensing and highlight novel tools to study nuclear mechanotransduction.
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214
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Stephens AD, Liu PZ, Banigan EJ, Almassalha LM, Backman V, Adam SA, Goldman RD, Marko JF. Chromatin histone modifications and rigidity affect nuclear morphology independent of lamins. Mol Biol Cell 2018; 29:220-233. [PMID: 29142071 PMCID: PMC5909933 DOI: 10.1091/mbc.e17-06-0410] [Citation(s) in RCA: 211] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/17/2017] [Accepted: 11/08/2017] [Indexed: 01/29/2023] Open
Abstract
Nuclear shape and architecture influence gene localization, mechanotransduction, transcription, and cell function. Abnormal nuclear morphology and protrusions termed "blebs" are diagnostic markers for many human afflictions including heart disease, aging, progeria, and cancer. Nuclear blebs are associated with both lamin and chromatin alterations. A number of prior studies suggest that lamins dictate nuclear morphology, but the contributions of altered chromatin compaction remain unclear. We show that chromatin histone modification state dictates nuclear rigidity, and modulating it is sufficient to both induce and suppress nuclear blebs. Treatment of mammalian cells with histone deacetylase inhibitors to increase euchromatin or histone methyltransferase inhibitors to decrease heterochromatin results in a softer nucleus and nuclear blebbing, without perturbing lamins. Conversely, treatment with histone demethylase inhibitors increases heterochromatin and chromatin nuclear rigidity, which results in reduced nuclear blebbing in lamin B1 null nuclei. Notably, increased heterochromatin also rescues nuclear morphology in a model cell line for the accelerated aging disease Hutchinson-Gilford progeria syndrome caused by mutant lamin A, as well as cells from patients with the disease. Thus, chromatin histone modification state is a major determinant of nuclear blebbing and morphology via its contribution to nuclear rigidity.
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Affiliation(s)
- Andrew D Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Patrick Z Liu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Edward J Banigan
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Luay M Almassalha
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Stephen A Adam
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
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215
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Auguste G, Gurha P, Lombardi R, Coarfa C, Willerson JT, Marian AJ. Suppression of Activated FOXO Transcription Factors in the Heart Prolongs Survival in a Mouse Model of Laminopathies. Circ Res 2018; 122:678-692. [PMID: 29317431 DOI: 10.1161/circresaha.117.312052] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/13/2017] [Accepted: 01/05/2018] [Indexed: 01/15/2023]
Abstract
RATIONALE Mutations in the LMNA gene, encoding nuclear inner membrane protein lamin A/C, cause distinct phenotypes, collectively referred to as laminopathies. Heart failure, conduction defects, and arrhythmias are the common causes of death in laminopathies. OBJECTIVE The objective of this study was to identify and therapeutically target the responsible mechanism(s) for cardiac phenotype in laminopathies. METHODS AND RESULTS Whole-heart RNA sequencing was performed before the onset of cardiac dysfunction in the Lmna-/- and matched control mice. Differentially expressed transcripts and their upstream regulators were identified, validated, and targeted by adeno-associated virus serotype 9-short hairpin RNA constructs. A total of 576 transcripts were upregulated and 233 were downregulated in the Lmna-/- mouse hearts (q<0.05). Forkhead box O (FOXO) transcription factors (TFs) were the most activated while E2 factors were the most suppressed transcriptional regulators. Transcript levels of FOXO targets were also upregulated in the isolated Lmna-/- cardiac myocytes and in the myocardium of human heart failure patients. Nuclear localization of FOXO1 and 3 was increased, whereas phosphorylated (inactive) FOXO1 and 3 levels were reduced in the Lmna-/- hearts. Gene set enrichment analysis and gene ontology showed activation of apoptosis and inflammation and suppression of cell cycle, adipogenesis, and oxidative phosphorylation in the Lmna-/- hearts. Adeno-associated virus serotype 9-short hairpin RNA-mediated suppression of FOXO TFs rescued selected molecular signatures, improved apoptosis, and prolonged survival by ≈2-fold. CONCLUSIONS FOXO TFs are activated and contribute to the pathogenesis of cardiac phenotype in laminopathies. Suppression of the FOXO TFs in cardiac myocytes partially rescues the phenotype and prolongs survival. The findings identify FOXO TFs as potential therapeutic targets for cardiac phenotype in laminopathies.
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Affiliation(s)
- Gaelle Auguste
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.)
| | - Priyatansh Gurha
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.)
| | - Raffaella Lombardi
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.)
| | - Cristian Coarfa
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.)
| | - James T Willerson
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.)
| | - Ali J Marian
- From the Center for Cardiovascular Genetics, Institute of Molecular Medicine and Department of Medicine, University of Texas Health Sciences Center at Houston (G.A., P.G., R.L., T.T.W., A.J.M.), Texas Heart Institute (J.T.W., A.J.M.); and Baylor College of Medicine, Houston, TX (C.C.).
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216
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Lamin A/C augments Th1 differentiation and response against vaccinia virus and Leishmania major. Cell Death Dis 2018; 9:9. [PMID: 29311549 PMCID: PMC5849043 DOI: 10.1038/s41419-017-0007-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 09/18/2017] [Accepted: 09/19/2017] [Indexed: 12/13/2022]
Abstract
Differentiation of naive CD4+ T-cells into functionally distinct T helper (Th) subsets is critical to immunity against pathogen infection. Little is known about the role of signals emanating from the nuclear envelope for T-cell differentiation. The nuclear envelope protein lamin A/C is induced in naive CD4+ T-cells upon antigen recognition and acts as a link between the nucleus and the plasma membrane during T-cell activation. Here we demonstrate that the absence of lamin A/C in naive T-cell reduces Th1 differentiation without affecting Th2 differentiation in vitro and in vivo. Moreover, Rag1−/− mice reconstituted with Lmna−/−CD4+CD25− T-cells and infected with vaccinia virus show weaker Th1 responses and viral removal than mice reconstituted with wild-type T-cells. Th1 responses and pathogen clearance upon Leishmania major infection were similarly diminished in mice lacking lamin A/C in the complete immune system or selectively in T-cells. Lamin A/C mediates Th1 polarization by a mechanism involving T-bet and IFNγ production. Our results reveal a novel role for lamin A/C as key regulator of Th1 differentiation in response to viral and intracellular parasite infections.
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217
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Nishiuchi S, Makiyama T, Aiba T, Nakajima K, Hirose S, Kohjitani H, Yamamoto Y, Harita T, Hayano M, Wuriyanghai Y, Chen J, Sasaki K, Yagihara N, Ishikawa T, Onoue K, Murakoshi N, Watanabe I, Ohkubo K, Watanabe H, Ohno S, Doi T, Shizuta S, Minamino T, Saito Y, Oginosawa Y, Nogami A, Aonuma K, Kusano K, Makita N, Shimizu W, Horie M, Kimura T. Gene-Based Risk Stratification for Cardiac Disorders in
LMNA
Mutation Carriers. ACTA ACUST UNITED AC 2017; 10:CIRCGENETICS.116.001603. [DOI: 10.1161/circgenetics.116.001603] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 09/25/2017] [Indexed: 01/01/2023]
Abstract
Background—
Mutations in
LMNA
(
lamin A/C
), which encodes lamin A and C, typically cause age-dependent cardiac phenotypes, including dilated cardiomyopathy, cardiac conduction disturbance, atrial fibrillation, and malignant ventricular arrhythmias. Although the type of
LMNA
mutations have been reported to be associated with susceptibility to malignant ventricular arrhythmias, the gene-based risk stratification for cardiac complications remains unexplored.
Methods and Results—
The multicenter cohort included 77
LMNA
mutation carriers from 45 families; cardiac disorders were retrospectively analyzed. The mean age of patients when they underwent genetic testing was 45±17, and they were followed for a median 49 months. Of the 77 carriers, 71 (92%) were phenotypically affected and showed cardiac conduction disturbance (81%), low left ventricular ejection fraction (<50%; 45%), atrial arrhythmias (58%), and malignant ventricular arrhythmias (26%). During the follow-up period, 9 (12%) died, either from end-stage heart failure (n=7) or suddenly (n=2). Genetic analysis showed truncation mutations in 58 patients from 31 families and missense mutations in 19 patients from 14 families. The onset of cardiac disorders indicated that subjects with truncation mutations had an earlier occurrence of cardiac conduction disturbance and low left ventricular ejection fraction, than those with missense mutations. In addition, the truncation mutation was found to be a risk factor for the early onset of cardiac conduction disturbance and the occurrence of atrial arrhythmias and low left ventricular ejection fraction, as estimated using multivariable analyses.
Conclusions—
The truncation mutations were associated with manifestation of cardiac phenotypes in
LMNA
-related cardiomyopathy, suggesting that genetic analysis might be useful for diagnosis and risk stratification.
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218
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Relevance of the p53-MDM2 axis to aging. Cell Death Differ 2017; 25:169-179. [PMID: 29192902 DOI: 10.1038/cdd.2017.187] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/19/2017] [Accepted: 09/21/2017] [Indexed: 12/13/2022] Open
Abstract
In response to varying stress signals, the p53 tumor suppressor is able to promote repair, survival, or elimination of damaged cells - processes that have great relevance to organismal aging. Although the link between p53 and cancer is well established, the contribution of p53 to the aging process is less clear. Delineating how p53 regulates distinct aging hallmarks such as cellular senescence, genomic instability, mitochondrial dysfunction, and altered metabolic pathways will be critical. Mouse models have further revealed the centrality and complexity of the p53 network in aging processes. While naturally aged mice have linked longevity with declining p53 function, some accelerated aging mice present with chronic p53 activation, whose phenotypes can be rescued upon p53 deficiency. Further, direct modulation of the p53-MDM2 axis has correlated elevated p53 activity with either early aging or with delayed-onset aging. We speculate that p53-mediated aging phenotypes in these mice must have (1) stably active p53 due to MDM2 dysregulation or chronic stress or (2) shifted p53 outcomes. Pinpointing which p53 stressors, modifications, and outcomes drive aging processes will provide further insights into our understanding of the human aging process and could have implications for both cancer and aging therapeutics.
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219
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Kolb T, Kraxner J, Skodzek K, Haug M, Crawford D, Maaß KK, Aifantis KE, Whyte G. Optomechanical measurement of the role of lamins in whole cell deformability. JOURNAL OF BIOPHOTONICS 2017; 10:1657-1664. [PMID: 28485113 DOI: 10.1002/jbio.201600198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 03/12/2017] [Accepted: 03/13/2017] [Indexed: 06/07/2023]
Abstract
There is mounting evidence that the nuclear envelope, and particularly the lamina, plays a critical role in the mechanical and regulation properties of the cell and changes to the lamina can have implications for the physical properties of the whole cell. In this study we demonstrate that the optical stretcher can measure changes in the time-dependent mechanical properties of living cells with different levels of A-type lamin expression. Results from the optical stretcher shows a decrease in the deformability of cells as the levels of lamin A increases, for cells which grow both adherently and in suspension. Further detail can be probed by combining the optical stretcher with fluorescence microscopy to investigate the nuclear mechanical properties which show a larger decrease in deformability than for the whole cell.
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Affiliation(s)
- Thorsten Kolb
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052, Erlangen, Germany
- Division of Molecular Genetics, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Julia Kraxner
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052, Erlangen, Germany
| | - Kai Skodzek
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Michael Haug
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052, Erlangen, Germany
| | - Dean Crawford
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Kendra K Maaß
- Division of Molecular Genetics, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Katerina E Aifantis
- Lab of Mechanics and Materials, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
- Department of Civil Engineering-Engineering Mechanics, University of Arizona, Tuscon, Arizona, 85721
| | - Graeme Whyte
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Henkestrasse 91, 91052, Erlangen, Germany
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK
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220
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Liao CY, Anderson SS, Chicoine NH, Mayfield JR, Academia EC, Wilson JA, Pongkietisak C, Thompson MA, Lagmay EP, Miller DM, Hsu YM, McCormick MA, O'Leary MN, Kennedy BK. Rapamycin Reverses Metabolic Deficits in Lamin A/C-Deficient Mice. Cell Rep 2017; 17:2542-2552. [PMID: 27926859 DOI: 10.1016/j.celrep.2016.10.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 07/27/2016] [Accepted: 10/13/2016] [Indexed: 01/26/2023] Open
Abstract
The role of the mTOR inhibitor, rapamycin, in regulation of adiposity remains controversial. Here, we evaluate mTOR signaling in lipid metabolism in adipose tissues of Lmna-/- mice, a mouse model for dilated cardiomyopathy and muscular dystrophy. Lifespan extension by rapamycin is associated with increased body weight and fat content, two phenotypes we link to suppression of elevated energy expenditure. In both white and brown adipose tissue of Lmna-/- mice, we find that rapamycin inhibits mTORC1 but not mTORC2, leading to suppression of elevated lipolysis and restoration of thermogenic protein UCP1 levels, respectively. The short lifespan and metabolic phenotypes of Lmna-/- mice can be partially rescued by maintaining mice at thermoneutrality. Together, our findings indicate that altered mTOR signaling in Lmna-/- mice leads to a lipodystrophic phenotype that can be rescued with rapamycin, highlighting the effect of loss of adipose tissue in Lmna-/- mice and the consequences of altered mTOR signaling.
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Affiliation(s)
- Chen-Yu Liao
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Sydney S Anderson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Nicole H Chicoine
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Jarrott R Mayfield
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Emmeline C Academia
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Joy A Wilson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | | | - Morgan A Thompson
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Earl P Lagmay
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Delana M Miller
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Yueh-Mei Hsu
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Mark A McCormick
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Monique N O'Leary
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Brian K Kennedy
- Buck Institute for Research on Aging, 8001 Redwood Blvd., Novato, CA 94945, USA.
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221
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Buxboim A, Irianto J, Swift J, Athirasala A, Shin JW, Rehfeldt F, Discher DE. Coordinated increase of nuclear tension and lamin-A with matrix stiffness outcompetes lamin-B receptor that favors soft tissue phenotypes. Mol Biol Cell 2017; 28:3333-3348. [PMID: 28931598 PMCID: PMC5687034 DOI: 10.1091/mbc.e17-06-0393] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/06/2017] [Accepted: 09/13/2017] [Indexed: 12/31/2022] Open
Abstract
Matrix stiffness that is sensed by a cell or measured by a purely physical probe reflects the intrinsic elasticity of the matrix and also how thick or thin the matrix is. Here, mesenchymal stem cells (MSCs) and their nuclei spread in response to thickness-corrected matrix microelasticity, with increases in nuclear tension and nuclear stiffness resulting from increases in myosin-II and lamin-A,C. Linearity between the widely varying projected area of a cell and its nucleus across many matrices, timescales, and myosin-II activity levels indicates a constant ratio of nucleus-to-cell volume, despite MSCs' lineage plasticity. Nuclear envelope fluctuations are suppressed on the stiffest matrices, and fluctuation spectra reveal a high nuclear tension that matches trends from traction force microscopy and from increased lamin-A,C. Transcriptomes of many diverse tissues and MSCs further show that lamin-A,C's increase with tissue or matrix stiffness anti-correlates with lamin-B receptor (LBR), which contributes to lipid/sterol biosynthesis. Adipogenesis (a soft lineage) indeed increases LBR:lamin-A,C protein stoichiometry in MSCs versus osteogenesis (stiff). The two factors compete for lamin-B in response to matrix elasticity, knockdown, myosin-II inhibition, and even constricted migration that disrupts and segregates lamins in situ. Matrix stiffness-driven contractility thus tenses the nucleus to favor lamin-A,C accumulation and suppress soft tissue phenotypes.
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Affiliation(s)
- Amnon Buxboim
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
- Department/Graduate Group of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
| | - Jerome Irianto
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Joe Swift
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Avathamsa Athirasala
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Jae-Won Shin
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Florian Rehfeldt
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
| | - Dennis E Discher
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104
- Department/Graduate Group of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104
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222
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Evidence that S6K1, but not 4E-BP1, mediates skeletal muscle pathology associated with loss of A-type lamins. Cell Discov 2017; 3:17039. [PMID: 29736257 PMCID: PMC5931234 DOI: 10.1038/celldisc.2017.39] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/04/2017] [Indexed: 12/22/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway plays a central role in aging and a number of different disease states. Rapamycin, which suppresses activity of the mTOR complex 1 (mTORC1), shows preclinical (and sometimes clinical) efficacy in a number of disease models. Among these are Lmna-/- mice, which serve as a mouse model for dystrophy-associated laminopathies. To confirm that elevated mTORC1 signaling is responsible for the pathology manifested in Lmna-/- mice and to decipher downstream genetic mechanisms underlying the benefits of rapamycin, we tested in Lmna-/- mice whether survival could be extended and disease pathology suppressed either by reduced levels of S6K1 or enhanced levels of 4E-BP1, two canonical mTORC1 substrates. Global heterozygosity for S6K1 ubiquitously extended lifespan of Lmna-/- mice (Lmna-/-S6K1+/- mice). This life extension is due to improving muscle, but not heart or adipose, function, consistent with the observation that genetic ablation of S6K1 specifically in muscle tissue also extended survival of Lmna-/- mice. In contrast, whole-body overexpression of 4E-BP1 shortened the survival of Lmna-/- mice, likely by accelerating lipolysis. Thus, rapamycin-mediated lifespan extension in Lmna-/- mice is in part due to the improvement of skeletal muscle function and can be phenocopied by reduced S6K1 activity, but not 4E-BP1 activation.
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223
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Perepelina K, Dmitrieva R, Ignatieva E, Borodkina A, Kostareva A, Malashicheva A. Lamin A/C mutation associated with lipodystrophy influences adipogenic differentiation of stem cells through interaction with Notch signaling. Biochem Cell Biol 2017; 96:342-348. [PMID: 29040816 DOI: 10.1139/bcb-2017-0210] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Lamins A and C are involved in many cellular functions, owing to its ability to bind chromatin and transcription factors and affect their properties. Mutations of the LMNA gene encoding lamin A/C affect differentiation capacity of stem cells. However, the signaling pathways involved in interactions with lamins during cellular differentiation remain unclear. Lipodystrophy associated with LMNA mutation R482L causes loss of fat tissue. In this study we investigated the role of LMNA mutation R482L in modulating Notch signaling activity in the adipogenic differentiation of mesenchymal stem cells. Notch was activated using lentiviral Notch intracellular domain. Activation of Notch was estimated through the expression of Notch-responsive genes by qPCR and by activation of a luciferase CSL-reporter construct. The effect of LMNA mutation on Notch activation and adipogenic differentiation was analyzed in cells bearing lentiviral LMNA WT or LMNA R482L. We show that, when Notch is activated, LMNA R482L contributes to down-regulation of Notch activation in undifferentiated and differentiated cells, and decreases adipogenic differentiation. Thus, lamin A/C interacts with Notch signaling, thereby influencing cellular differentiation, and point mutation in LMNA could halt this interaction.
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Affiliation(s)
- K Perepelina
- e Almazov National Medical Research Centre, 2 Akkuratova street, Saint-Petersburg 197341, Russia.,f Saint-Petersburg State University, 7/9, Universitetskaya nab., Saint-Petersburg, 199034, Russia
| | - R Dmitrieva
- a Almazov National Medical Research Centre, Saint-Petersburg, Russia
| | - E Ignatieva
- a Almazov National Medical Research Centre, Saint-Petersburg, Russia
| | - A Borodkina
- c Institute of Cytology, Russian Academy of Sciences, 4, Tikhoretsky ave., Saint-Petersburg, 194064, Russia
| | - A Kostareva
- a Almazov National Medical Research Centre, Saint-Petersburg, Russia.,g ITMO University, Institute of Translational Medicine, 49 Kronverkskiy ave., Saint-Petersburg, 197101, Russia
| | - A Malashicheva
- a Almazov National Medical Research Centre, Saint-Petersburg, Russia.,b Saint-Petersburg State University, Saint-Petersburg, Russia.,d ITMO University, Institute of Translational Medicine, Saint-Petersburg, Russia
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224
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Zhou C, Li C, Zhou B, Sun H, Koullourou V, Holt I, Puckelwartz MJ, Warren DT, Hayward R, Lin Z, Zhang L, Morris GE, McNally EM, Shackleton S, Rao L, Shanahan CM, Zhang Q. Novel nesprin-1 mutations associated with dilated cardiomyopathy cause nuclear envelope disruption and defects in myogenesis. Hum Mol Genet 2017; 26:2258-2276. [PMID: 28398466 PMCID: PMC5458344 DOI: 10.1093/hmg/ddx116] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 03/22/2017] [Indexed: 02/05/2023] Open
Abstract
Nesprins-1 and -2 are highly expressed in skeletal and cardiac muscle and together with SUN (Sad1p/UNC84)-domain containing proteins and lamin A/C form the LInker of Nucleoskeleton-and-Cytoskeleton (LINC) bridging complex at the nuclear envelope (NE). Mutations in nesprin-1/2 have previously been found in patients with autosomal dominant Emery–Dreifuss muscular dystrophy (EDMD) as well as dilated cardiomyopathy (DCM). In this study, three novel rare variants (R8272Q, S8381C and N8406K) in the C-terminus of the SYNE1 gene (nesprin-1) were identified in seven DCM patients by mutation screening. Expression of these mutants caused nuclear morphology defects and reduced lamin A/C and SUN2 staining at the NE. GST pull-down indicated that nesprin-1/lamin/SUN interactions were disrupted. Nesprin-1 mutations were also associated with augmented activation of the ERK pathway in vitro and in hearts in vivo. During C2C12 muscle cell differentiation, nesprin-1 levels are increased concomitantly with kinesin light chain (KLC-1/2) and immunoprecipitation and GST pull-down showed that these proteins interacted via a recently identified LEWD domain in the C-terminus of nesprin-1. Expression of nesprin-1 mutants in C2C12 cells caused defects in myoblast differentiation and fusion associated with dysregulation of myogenic transcription factors and disruption of the nesprin-1 and KLC-1/2 interaction at the outer nuclear membrane. Expression of nesprin-1α2 WT and mutants in zebrafish embryos caused heart developmental defects that varied in severity. These findings support a role for nesprin-1 in myogenesis and muscle disease, and uncover a novel mechanism whereby disruption of the LINC complex may contribute to the pathogenesis of DCM.
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Affiliation(s)
- Can Zhou
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5 9NU, UK.,Department of Cardiology, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Chen Li
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5 9NU, UK.,Department of Cardiology, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Bin Zhou
- Laboratory of Molecular Translational Medicine.,Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education
| | - Huaqin Sun
- Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education.,SCU-CUHK Joint Laboratory for Reproductive Medicine, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Victoria Koullourou
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5 9NU, UK.,Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, UK
| | - Ian Holt
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10?7AG, UK and Institute for Science and Technology in Medicine, Keele University, ST5?5BG, UK
| | - Megan J Puckelwartz
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Derek T Warren
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5?9NU, UK
| | - Robert Hayward
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5?9NU, UK
| | - Ziyuan Lin
- Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education.,SCU-CUHK Joint Laboratory for Reproductive Medicine, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Lin Zhang
- Laboratory of Molecular Translational Medicine.,Key Laboratory of Obstetric & Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education
| | - Glenn E Morris
- Wolfson Centre for Inherited Neuromuscular Disease, RJAH Orthopaedic Hospital, Oswestry SY10?7AG, UK and Institute for Science and Technology in Medicine, Keele University, ST5?5BG, UK
| | - Elizabeth M McNally
- Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Sue Shackleton
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1?9HN, UK
| | - Li Rao
- Department of Cardiology, West China Hospital of Sichuan University, Chengdu 610041, China
| | - Catherine M Shanahan
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5?9NU, UK
| | - Qiuping Zhang
- King's College London British Heart Foundation Centre of Research Excellence, Cardiovascular Division, London SE5?9NU, UK
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225
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Shin JY, Méndez-López I, Hong M, Wang Y, Tanji K, Wu W, Shugol L, Krauss RS, Dauer WT, Worman HJ. Lamina-associated polypeptide 1 is dispensable for embryonic myogenesis but required for postnatal skeletal muscle growth. Hum Mol Genet 2017; 26:65-78. [PMID: 27798115 DOI: 10.1093/hmg/ddw368] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 10/21/2016] [Indexed: 12/17/2022] Open
Abstract
Lamina-associated polypeptide 1 (LAP1) is an integral protein of the inner nuclear membrane that has been implicated in striated muscle maintenance. Mutations in its gene have been linked to muscular dystrophy and cardiomyopathy. As germline deletion of the gene encoding LAP1 is perinatal lethal, we explored its potential role in myogenic differentiation and development by generating a conditional knockout mouse in which the protein is depleted from muscle progenitors at embryonic day 8.5 (Myf5-Lap1CKO mice). Although cultured myoblasts lacking LAP1 demonstrated defective terminal differentiation and altered expression of muscle regulatory factors, embryonic myogenesis and formation of skeletal muscle occurred in both mice with a Lap1 germline deletion and Myf5-Lap1CKO mice. However, skeletal muscle fibres were hypotrophic and their nuclei were morphologically abnormal with a wider perinuclear space than normal myonuclei. Myf5-Lap1CKO mouse skeletal muscle contained fewer satellite cells than normal and these cells had evidence of reduced myogenic potential. Abnormalities in signalling pathways required for postnatal hypertrophic growth were also observed in skeletal muscles of these mice. Our results demonstrate that early embryonic depletion of LAP1 does not impair myogenesis but that it is necessary for postnatal skeletal muscle growth.
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Affiliation(s)
- Ji-Yeon Shin
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Iván Méndez-López
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Mingi Hong
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Yuexia Wang
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Kurenai Tanji
- Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Wei Wu
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Leana Shugol
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Robert S Krauss
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - William T Dauer
- Department of Neurology.,Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Howard J Worman
- Department of Medicine.,Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, New York, NY, USA
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226
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Bártová E, Suchánková J, Legartová S, Malyšková B, Hornáček M, Skalníková M, Mašata M, Raška I, Kozubek S. PCNA is recruited to irradiated chromatin in late S-phase and is most pronounced in G2 phase of the cell cycle. PROTOPLASMA 2017; 254:2035-2043. [PMID: 28168519 DOI: 10.1007/s00709-017-1076-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 01/09/2017] [Indexed: 06/06/2023]
Abstract
DNA repair is a complex process that prevents genomic instability. Many proteins play fundamental roles in regulating the optimal repair of DNA lesions. Proliferating cell nuclear antigen (PCNA) is a key factor that initiates recombination-associated DNA synthesis after injury. Here, in very early S-phase, we show that the fluorescence intensity of mCherry-tagged PCNA after local micro-irradiation was less than the fluorescence intensity of non-irradiated mCherry-PCNA-positive replication foci. However, PCNA protein accumulated at locally irradiated chromatin in very late S-phase of the cell cycle, and this effect was more pronounced in the following G2 phase. In comparison to the dispersed form of PCNA, a reduced mobile fraction appeared in PCNA-positive replication foci during S-phase, and we observed similar recovery time after photobleaching at locally induced DNA lesions. This diffusion of mCherry-PCNA in micro-irradiated regions was not affected by cell cycle phases. We also studied the link between function of PCNA and A-type lamins in late S-phase. We found that the accumulation of PCNA at micro-irradiated chromatin is identical in wild-type and A-type lamin-deficient cells. Only micro-irradiation of the nuclear interior, and thus the irradiation of internal A-type lamins, caused the fluorescence intensity of mCherry-tagged PCNA to increase. In summary, we showed that PCNA begins to play a role in DNA repair in late S-phase and that PCNA function in repair is maintained during the G2 phase of the cell cycle. However, PCNA mobility is reduced after local micro-irradiation regardless of the cell cycle phase.
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Affiliation(s)
- Eva Bártová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic.
| | - Jana Suchánková
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Soňa Legartová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Barbora Malyšková
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Matúš Hornáček
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01, Prague, Czech Republic
| | - Magdalena Skalníková
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01, Prague, Czech Republic
| | - Martin Mašata
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01, Prague, Czech Republic
| | - Ivan Raška
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01, Prague, Czech Republic
| | - Stanislav Kozubek
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
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227
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Norton HK, Phillips-Cremins JE. Crossed wires: 3D genome misfolding in human disease. J Cell Biol 2017; 216:3441-3452. [PMID: 28855250 PMCID: PMC5674879 DOI: 10.1083/jcb.201611001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 06/09/2017] [Accepted: 08/16/2017] [Indexed: 12/13/2022] Open
Abstract
Norton and Phillips-Cremins review the 3D architecture of the genome and discuss links between chromatin misfolding and human diseases. Mammalian genomes are folded into unique topological structures that undergo precise spatiotemporal restructuring during healthy development. Here, we highlight recent advances in our understanding of how the genome folds inside the 3D nucleus and how these folding patterns are miswired during the onset and progression of mammalian disease states. We discuss potential mechanisms underlying the link among genome misfolding, genome dysregulation, and aberrant cellular phenotypes. We also discuss cases in which the endogenous 3D genome configurations in healthy cells might be particularly susceptible to mutation or translocation. Together, these data support an emerging model in which genome folding and misfolding is critically linked to the onset and progression of a broad range of human diseases.
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Affiliation(s)
- Heidi K Norton
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA
| | - Jennifer E Phillips-Cremins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA .,Epigenetics Program, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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228
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Takaki T, Montagner M, Serres MP, Le Berre M, Russell M, Collinson L, Szuhai K, Howell M, Boulton SJ, Sahai E, Petronczki M. Actomyosin drives cancer cell nuclear dysmorphia and threatens genome stability. Nat Commun 2017; 8:16013. [PMID: 28737169 PMCID: PMC5527285 DOI: 10.1038/ncomms16013] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 05/24/2017] [Indexed: 12/16/2022] Open
Abstract
Altered nuclear shape is a defining feature of cancer cells. The mechanisms underlying nuclear dysmorphia in cancer remain poorly understood. Here we identify PPP1R12A and PPP1CB, two subunits of the myosin phosphatase complex that antagonizes actomyosin contractility, as proteins safeguarding nuclear integrity. Loss of PPP1R12A or PPP1CB causes nuclear fragmentation, nuclear envelope rupture, nuclear compartment breakdown and genome instability. Pharmacological or genetic inhibition of actomyosin contractility restores nuclear architecture and genome integrity in cells lacking PPP1R12A or PPP1CB. We detect actin filaments at nuclear envelope rupture sites and define the Rho-ROCK pathway as the driver of nuclear damage. Lamin A protects nuclei from the impact of actomyosin activity. Blocking contractility increases nuclear circularity in cultured cancer cells and suppresses deformations of xenograft nuclei in vivo. We conclude that actomyosin contractility is a major determinant of nuclear shape and that unrestrained contractility causes nuclear dysmorphia, nuclear envelope rupture and genome instability.
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Affiliation(s)
- Tohru Takaki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Marco Montagner
- Tumour Cell Biology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Murielle P. Serres
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- MRC Laboratory for Molecular Cell Biology, UCL, Gower Street, London WC1E 6BT, UK
| | - Maël Le Berre
- Institut Curie, PSL Research University, CNRS, UMR 144, F-75005 Paris, France
| | - Matt Russell
- Electron Microscopy Group, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Lucy Collinson
- Electron Microscopy Group, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Karoly Szuhai
- Department of Molecular Cell Biology, LUMC, Einthovenweg 20, 2333 ZC Leiden, The Netherlands
| | - Michael Howell
- High Throughput Screening Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Simon J. Boulton
- DSB Repair Metabolism Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Erik Sahai
- Tumour Cell Biology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Mark Petronczki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK
- Boehringer Ingelheim RCV GmbH & Co KG, Dr Boehringer Gasse 5-11, A-1121 Vienna, Austria
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229
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Lindqvist J, Torvaldson E, Gullmets J, Karvonen H, Nagy A, Taimen P, Eriksson JE. Nestin contributes to skeletal muscle homeostasis and regeneration. J Cell Sci 2017; 130:2833-2842. [PMID: 28733456 DOI: 10.1242/jcs.202226] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 07/12/2017] [Indexed: 01/15/2023] Open
Abstract
Nestin, a member of the cytoskeletal family of intermediate filaments, regulates the onset of myogenic differentiation through bidirectional signaling with the kinase Cdk5. Here, we show that these effects are also reflected at the organism level, as there is a loss of skeletal muscle mass in nestin-/- (NesKO) mice, reflected as reduced lean (muscle) mass in the mice. Further examination of muscles in male mice revealed that these effects stemmed from nestin-deficient muscles being more prone to spontaneous regeneration. When the regeneration capacity of the compromised NesKO muscle was tested by muscle injury experiments, a significant healing delay was observed. NesKO satellite cells showed delayed proliferation kinetics in conjunction with an elevation in p35 (encoded by Cdk5r1) levels and Cdk5 activity. These results reveal that nestin deficiency generates a spontaneous regenerative phenotype in skeletal muscle that relates to a disturbed proliferation cycle that is associated with uncontrolled Cdk5 activity.
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Affiliation(s)
- Julia Lindqvist
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, 20520, Finland.,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Elin Torvaldson
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, 20520, Finland.,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Josef Gullmets
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, 20520, Finland.,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland.,Department of Pathology, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | - Henok Karvonen
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, 20520, Finland.,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland
| | - Andras Nagy
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, M5G 1X5, Canada
| | - Pekka Taimen
- Department of Pathology, University of Turku and Turku University Hospital, 20520 Turku, Finland
| | - John E Eriksson
- Cell Biology, Biosciences, Faculty of Science and Engineering, Åbo Akademi University, Turku, 20520, Finland .,Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520, Turku, Finland
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230
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De Loof A. Calcitox-aging counterbalanced by endogenous farnesol-like sesquiterpenoids: An undervalued evolutionarily ancient key signaling pathway. Commun Integr Biol 2017; 10:e1341024. [PMID: 28919940 PMCID: PMC5595427 DOI: 10.1080/19420889.2017.1341024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 06/07/2017] [Indexed: 02/08/2023] Open
Abstract
Cells are powerful miniature electrophoresis chambers, at least during part of their life cycle. They die at the moment the voltage gradient over their plasma membrane, and their ability to drive a self-generated electric current carried by inorganic ions through themselves irreversibly collapses. Senescence is likely due to the progressive, multifactorial damage to the cell's electrical system. This is the essence of the "Fading electricity theory of aging" (De Loof et al., Aging Res. Rev. 2013;12:58-66). "Biologic electric current" is not carried by electrons, but by inorganic ions. The major ones are H+, Na+, K+, Ca2+, Mg2+, Cl- and HCO3-. Ca2+ and H+ in particular are toxic to cells. At rising concentrations, they can alter the 3D-conformation of chromatin and some (e.g. cytoskeletal) proteins: Calcitox and Protontox. This paper only focuses on Calcitox and endogenous sesquiterpenoids. pH-control and Ca2+-homeostasis have been shaped to near perfection during billions of years of evolution. The role of Ca2+ in some aspects of aging, e.g., as causal to neurodegenerative diseases is still debated. The main anti-Calcitox mechanism is to keep free cytoplasmic Ca2+ as low as possible. This can be achieved by restricting the passive influx of Ca2+ through channels in the plasma membrane, and by maximizing the active extrusion of excess Ca2+ e.g., by means of different types of Ca2+-ATPases. Like there are mechanisms that antagonize the toxic effects of Reactive Oxygen Species (ROS), there must also exist endogenous tools to counteract Calcitox. During a re-evaluation of which mechanism(s) exactly initiates the fast aging that accompanies induction of metamorphosis in insects, a causal relationship between absence of an endogenous sesquiterpenoid, namely the farnesol ester named "juvenile hormone," and disturbed Ca2+-homeostasis was suggested. In this paper, this line of thinking is further explored and extended to vertebrate physiology. A novel concept emerges: horseshoe-shaped sesquiterpenoids seem to act as "inbrome" agonists with the function of a "chemical valve" or "spring" in some types of multi-helix transmembrane proteins (intramolecular prenylation), from bacterial rhodopsins to some types of GPCRs and ion pumps, in particular the SERCA-Ca2+-pump. This further underpins the Fading Electricity Theory of Aging.
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Affiliation(s)
- Arnold De Loof
- Functional Genomics and Proteomics Group, Department of Biology, KU Leuven-University of Leuven, Leuven, Belgium
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231
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Martinon F. Inflammation initiated by stressed organelles. Joint Bone Spine 2017; 85:423-428. [PMID: 28705494 DOI: 10.1016/j.jbspin.2017.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 06/29/2017] [Indexed: 12/21/2022]
Abstract
Key cellular functions including those related to energy metabolism, organization of the genetic information or production of membrane-bound and secreted proteins are compartmentalized within organelles. Various stresses such as differentiation programs, viral and bacterial infections, perturbations in protein production, mechanical constraints, changes in the environment and nutriment accessibility can impact cellular homeostasis and organelle integrity. Perturbations of these cellular compartments trigger repair and adaptation programs aimed at restoring homeostasis. These events are often associated with low-grade inflammation also termed parainflammation. While the nature and mechanisms of danger signals released by irremediably damaged cells are well understood, how transiently stressed cells trigger inflammation is still poorly understood. Emerging studies highlighted new mechanisms by which stress pathways promote inflammation. Cytosolic innate immune pathways are engaged by signals stemming from perturbed organelles such as the mitochondria, the endoplasmic reticulum (ER) or the nuclear envelope (NE). These observations indicate that these pathways function as guardians of cellular homeostasis and may contribute to disease in pathologies characterized by perturbations of cellular homoeostasis. Mitochondria-stress, ER-stress or NE-stress are emerging as proinflammatory signals that contribute to human conditions and diseases.
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Affiliation(s)
- Fabio Martinon
- Department of Biochemistry, University of Lausanne, Chemin Des Boveresses 155, 1066 Epalinges, Switzerland.
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232
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Kwan R, Brady GF, Brzozowski M, Weerasinghe SV, Martin H, Park MJ, Brunt MJ, Menon RK, Tong X, Yin L, Stewart CL, Omary MB. Hepatocyte-Specific Deletion of Mouse Lamin A/C Leads to Male-Selective Steatohepatitis. Cell Mol Gastroenterol Hepatol 2017; 4:365-383. [PMID: 28913408 PMCID: PMC5582719 DOI: 10.1016/j.jcmgh.2017.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 06/30/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND & AIMS Lamins are nuclear intermediate filament proteins that comprise the major components of the nuclear lamina. Mutations in LMNA, which encodes lamins A/C, cause laminopathies, including lipodystrophy, cardiomyopathy, and premature aging syndromes. However, the role of lamins in the liver is unknown, and it is unclear whether laminopathy-associated liver disease is caused by primary hepatocyte defects or systemic alterations. METHODS To address these questions, we generated mice carrying a hepatocyte-specific deletion of Lmna (knockout [KO] mice) and characterized the KO liver and primary hepatocyte phenotypes by immunoblotting, immunohistochemistry, microarray analysis, quantitative real-time polymerase chain reaction, and Oil Red O and Picrosirius red staining. RESULTS KO hepatocytes manifested abnormal nuclear morphology, and KO mice showed reduced body mass. KO mice developed spontaneous male-selective hepatosteatosis with increased susceptibility to high-fat diet-induced steatohepatitis and fibrosis. The hepatosteatosis was associated with up-regulated transcription of genes encoding lipid transporters, lipid biosynthetic enzymes, lipid droplet-associated proteins, and interferon-regulated genes. Hepatic Lmna deficiency led to enhanced signal transducer and activator of transcription 1 (Stat1) expression and blocked growth hormone-mediated Janus kinase 2 (Jak2), signal transducer and activator of transcription 5 (Stat5), and extracellular signal-regulated kinase (Erk) signaling. CONCLUSIONS Lamin A/C acts cell-autonomously to maintain hepatocyte homeostasis and nuclear shape and buffers against male-selective steatohepatitis by positively regulating growth hormone signaling and negatively regulating Stat1 expression. Lamins are potential genetic modifiers for predisposition to steatohepatitis and liver fibrosis. The microarray data can be found in the Gene Expression Omnibus repository (accession number: GSE93643).
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Key Words
- % liver weight, liver percentage of body mass
- Erk, extracellular signal–regulated kinase
- FPLD2, Dunnigan familial partial lipodystrophy
- Fibrosis
- GH, growth hormone
- Growth Hormone Signaling
- HFD, high-fat diet
- Het, heterozygous
- Igf1, insulin-like growth factor 1
- Jak2, Janus kinase 2
- KO, knockout
- Laminopathy
- Lipodystrophy
- NAFLD, nonalcoholic fatty liver disease
- ND, normal diet
- Nonalcoholic Fatty Liver Disease
- PBS, phosphate-buffered saline
- Stat, signal transducer and activator of transcription
- WT, wild type
- qPCR, quantitative polymerase chain reaction
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Affiliation(s)
- Raymond Kwan
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan,Correspondence Address correspondence to: Raymond Kwan, Department of Molecular and Integrative Physiology, University of Michigan, 7720 Med Sci II, Ann Arbor, Michigan 48109.Department of Molecular and Integrative PhysiologyUniversity of Michigan7720 Med Sci IIAnn ArborMichigan 48109
| | - Graham F. Brady
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Maria Brzozowski
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Sujith V. Weerasinghe
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Hope Martin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Min-Jung Park
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Makayla J. Brunt
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Ram K. Menon
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Xin Tong
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Lei Yin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Colin L. Stewart
- Development and Regenerative Biology Group, Institute of Medical Biology, Immunos, Singapore
| | - M. Bishr Omary
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
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233
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Monis WJ, Faundez V, Pazour GJ. BLOC-1 is required for selective membrane protein trafficking from endosomes to primary cilia. J Cell Biol 2017; 216:2131-2150. [PMID: 28576874 PMCID: PMC5496619 DOI: 10.1083/jcb.201611138] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 03/24/2017] [Accepted: 05/03/2017] [Indexed: 11/30/2022] Open
Abstract
Primary cilia perceive the extracellular environment through receptors localized in the ciliary membrane, but mechanisms directing specific proteins to this domain are poorly understood. To address this question, we knocked down proteins potentially important for ciliary membrane targeting and determined how this affects the ciliary trafficking of fibrocystin, polycystin-2, and smoothened. Our analysis showed that fibrocystin and polycystin-2 are dependent on IFT20, GMAP210, and the exocyst complex, while smoothened delivery is largely independent of these components. In addition, we found that polycystin-2, but not smoothened or fibrocystin, requires the biogenesis of lysosome-related organelles complex-1 (BLOC-1) for ciliary delivery. Consistent with the role of BLOC-1 in sorting from the endosome, we find that disrupting the recycling endosome reduces ciliary polycystin-2 and causes its accumulation in the recycling endosome. This is the first demonstration of a role for BLOC-1 in ciliary assembly and highlights the complexity of pathways taken to the cilium.
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Affiliation(s)
- William J Monis
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, GA
| | - Gregory J Pazour
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA
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234
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Ahmed MS, Ikram S, Bibi N, Mir A. Hutchinson-Gilford Progeria Syndrome: A Premature Aging Disease. Mol Neurobiol 2017; 55:4417-4427. [PMID: 28660486 DOI: 10.1007/s12035-017-0610-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/10/2017] [Indexed: 12/15/2022]
Abstract
Progeria is sporadic, very rare, autosomal dominant, deadly childhood disorder. It is one of the progeroid syndromes also known as Hutchinson-Gilford progeria syndrome (HGPS). Aging is a developmental process that begins with fertilization and ends up with death involving a lot of environmental and genetic factors. The disease firstly involves premature aging and then death from complications of atherosclerosis such as myocardial infarction, stroke, atherosclerosis, or heart failure. The lifespan of the patient is normally up to teen age or early twenties. It is usually not inherited because a patient normally dies before the age of reproduction. The most important genetic linkage between progeria and aging is shortening of telomere ends with each replication cycle. The patients are normally observed to have extremely short telomeres. Currently, 90% of the patients are said to have de novo point mutations in the LMNA gene that substitute cytosine with thymine and have been found in individuals with HGPS. Lmna encodes lamins A and C, and the A-type lamins have important structural function in the nuclear envelope. The most common type of HGPS mutation is located at codon 608 (G608G). It could not be diagnosed at birth, but after the age of 2 years, visible, prominent symptoms can be observed. Still, lot of research is needed to solve this mystery; hopefully, future research on HGPS would provide important clues for progeria and other fatal age-related disorders.
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Affiliation(s)
- Muhammad Saad Ahmed
- Department of Bioinformatics and Biotechnology, Faculty of Basic and Applied Sciences, International Islamic University, Islamabad, Pakistan.,Department of Biological Engineering/Institute of Biotransformation and Synthetic Biosystem, School of Life Sciences, Beijing Institute of Technology, Beijing, 100081, People's Republic of China
| | - Sana Ikram
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University (BTBU), 11 Fucheng Road, Beijing, 100048, People's Republic of China
| | - Nousheen Bibi
- Department of Bioinformatics, Hazara University, Mansehra, Pakistan.,National Center for Bioinformatics, Quaid-e-Azam University, Islamabad, Pakistan
| | - Asif Mir
- Department of Bioinformatics and Biotechnology, Faculty of Basic and Applied Sciences, International Islamic University, Islamabad, Pakistan.
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235
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Fenelon KD, Hopyan S. Structural components of nuclear integrity with gene regulatory potential. Curr Opin Cell Biol 2017. [PMID: 28641117 DOI: 10.1016/j.ceb.2017.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The nucleus is a mechanosensitive and load-bearing structure. Structural components of the nucleus interact to maintain nuclear integrity and have become subjects of exciting research that is relevant to cell and developmental biology. Here we outline the boundaries of what is known about key architectural elements within the nucleus and highlight their potential structural and transcriptional regulatory functions.
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Affiliation(s)
- Kelli D Fenelon
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada
| | - Sevan Hopyan
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada; Division of Orthopaedic Surgery, Hospital for Sick Children and University of Toronto, M5G 1X8, Canada.
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236
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Birendra Kc, May DG, Benson BV, Kim DI, Shivega WG, Ali MH, Faustino RS, Campos AR, Roux KJ. VRK2A is an A-type lamin-dependent nuclear envelope kinase that phosphorylates BAF. Mol Biol Cell 2017. [PMID: 28637768 PMCID: PMC5555652 DOI: 10.1091/mbc.e17-03-0138] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
By the use of comparative BioID of nuclear envelope (NE) proteins lamin A and Sun2, as well as a minimal inner nuclear membrane targeting motif, VRK2 is identified as a novel constituent of the NE. A-type lamins retain the transmembrane kinase VRK2 at the NE, where it phosphorylates and regulates the nuclear mobility of BAF. The nuclear envelope (NE) is critical for numerous fundamental cellular functions, and mutations in several NE constituents can lead to a heterogeneous spectrum of diseases. We used proximity biotinylation to uncover new constituents of the inner nuclear membrane (INM) by comparative BioID analysis of lamin A, Sun2 and a minimal INM-targeting motif. These studies identify vaccinia-related kinase-2 (VRK2) as a candidate constituent of the INM. The transmembrane VRK2A isoform is retained at the NE by association with A-type lamins. Furthermore, VRK2A physically interacts with A-type, but not B-type, lamins. Finally, we show that VRK2 phosphorylates barrier to autointegration factor (BAF), a small and highly dynamic chromatin-binding protein, which has roles including NE reassembly, cell cycle, and chromatin organization in cells, and subtly alters its nuclear mobility. Together these findings support the value of using BioID to identify unrecognized constituents of distinct subcellular compartments refractory to biochemical isolation and reveal VRK2A as a transmembrane kinase in the NE that regulates BAF.
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Affiliation(s)
- Birendra Kc
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Danielle G May
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Benjamin V Benson
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Dae In Kim
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Winnie G Shivega
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Manaal H Ali
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104
| | - Randolph S Faustino
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104.,Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57105
| | - Alexandre R Campos
- Proteomics Facility, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92037
| | - Kyle J Roux
- Sanford Children's Health Research Center, Sanford Research, Sioux Falls, SD 57104 .,Department of Pediatrics, Sanford School of Medicine, University of South Dakota, Sioux Falls, SD 57105
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237
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Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
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Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
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238
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Isoforms of the nuclear envelope protein Nurim are differentially expressed during heart development in mice. Gene 2017; 627:123-128. [PMID: 28600179 DOI: 10.1016/j.gene.2017.06.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 05/25/2017] [Accepted: 06/05/2017] [Indexed: 11/22/2022]
Abstract
To date, transcript variants of the nuclear envelope protein Nurim and their expression profiles in mice have never been elucidated. In this study, we determined that the primary Nurim variant a was abundantly expressed in mouse heart, liver, spleen and kidney. The protein level of isoform a is initiated at an early stage of heart formation and demonstrated a significant increase in expression throughout embryonic heart development. Interestingly, Nurim b is also up-regulated from E12.5 to E18.5 in different individuals. Our research represents the first report on alternative splicing variants of mouse Nurim and their differential expression profile during embryonic development. These studies suggest a potential role for Nurim in early heart morphogenesis and should help further elucidate the function of Nurim.
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239
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Rauschert I, Aldunate F, Preussner J, Arocena-Sutz M, Peraza V, Looso M, Benech JC, Agrelo R. Promoter hypermethylation as a mechanism for Lamin A/C silencing in a subset of neuroblastoma cells. PLoS One 2017; 12:e0175953. [PMID: 28422997 PMCID: PMC5397038 DOI: 10.1371/journal.pone.0175953] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 04/03/2017] [Indexed: 02/07/2023] Open
Abstract
Nuclear lamins support the nuclear envelope and provide anchorage sites for chromatin. They are involved in DNA synthesis, transcription, and replication. It has previously been reported that the lack of Lamin A/C expression in lymphoma and leukaemia is due to CpG island promoter hypermethylation. Here, we provide evidence that Lamin A/C is silenced via this mechanism in a subset of neuroblastoma cells. Moreover, Lamin A/C expression can be restored with a demethylating agent. Importantly, Lamin A/C reintroduction reduced cell growth kinetics and impaired migration, invasion, and anchorage-independent cell growth. Cytoskeletal restructuring was also induced. In addition, the introduction of lamin Δ50, known as Progerin, caused senescence in these neuroblastoma cells. These cells were stiffer and developed a cytoskeletal structure that differed from that observed upon Lamin A/C introduction. Of relevance, short hairpin RNA Lamin A/C depletion in unmethylated neuroblastoma cells enhanced the aforementioned tumour properties. A cytoskeletal structure similar to that observed in methylated cells was induced. Furthermore, atomic force microscopy revealed that Lamin A/C knockdown decreased cellular stiffness in the lamellar region. Finally, the bioinformatic analysis of a set of methylation arrays of neuroblastoma primary tumours showed that a group of patients (around 3%) gives a methylation signal in some of the CpG sites located within the Lamin A/C promoter region analysed by bisulphite sequencing PCR. These findings highlight the importance of Lamin A/C epigenetic inactivation for a subset of neuroblastomas, leading to enhanced tumour properties and cytoskeletal changes. Additionally, these findings may have treatment implications because tumour cells lacking Lamin A/C exhibit more aggressive behaviour.
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Affiliation(s)
- Ines Rauschert
- Laboratory of Cellular Signaling and Nanobiology, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Fabian Aldunate
- Epigenetics of Cancer and Aging Laboratory, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Jens Preussner
- Bioinformatics Core Unit (BCU), Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Miguel Arocena-Sutz
- Epigenetics of Cancer and Aging Laboratory, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Vanina Peraza
- Epigenetics of Cancer and Aging Laboratory, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Mario Looso
- Bioinformatics Core Unit (BCU), Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Juan C. Benech
- Laboratory of Cellular Signaling and Nanobiology, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Ruben Agrelo
- Epigenetics of Cancer and Aging Laboratory, Institut Pasteur de Montevideo, Montevideo, Uruguay
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240
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Wang X, Zabell A, Koh W, Tang WHW. Lamin A/C Cardiomyopathies: Current Understanding and Novel Treatment Strategies. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2017; 19:21. [PMID: 28299614 DOI: 10.1007/s11936-017-0520-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OPINION STATEMENT Dilated cardiomyopathy (DCM) is the third leading cause of heart failure in the USA. A major gene associated with DCM with cardiac conduction system disease is lamin A/C (LMNA) gene. Lamins are type V filaments that serve a variety of roles, including nuclear structure support, DNA repair, cell signaling pathway mediation, and chromatin organization. In 1999, LMNA was found responsible for Emery-Dreifuss muscular dystrophy (EDMD) and, since then, has been found in association with a wide spectrum of diseases termed laminopathies, including LMNA cardiomyopathy. Patients with LMNA mutations have a poor prognosis and a higher risk for sudden cardiac death, along with other cardiac effects like dysrhythmias, development of congestive heart failure, and potential need of a pacemaker or ICD. As of now, there is no specific treatment for laminopathies, including LMNA cardiomyopathy, because the mechanism of LMNA mutations in humans is still unclear. This review discusses LMNA mutations and how they relate to DCM, the necessity for further investigation to better understand LMNA mutations, and potential treatment options ranging from clinical and therapeutic to cellular and molecular techniques.
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Affiliation(s)
- Xi Wang
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland, OH, USA
| | - Allyson Zabell
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland, OH, USA
| | - Wonshill Koh
- Children's Hospital of Pittsburgh, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - W H Wilson Tang
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland, OH, USA. .,Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, OH, USA. .,Center for Clinical Genomics, Cleveland Clinic, Cleveland, OH, USA.
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241
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Thanisch K, Song C, Engelkamp D, Koch J, Wang A, Hallberg E, Foisner R, Leonhardt H, Stewart CL, Joffe B, Solovei I. Nuclear envelope localization of LEMD2 is developmentally dynamic and lamin A/C dependent yet insufficient for heterochromatin tethering. Differentiation 2017; 94:58-70. [PMID: 28056360 DOI: 10.1016/j.diff.2016.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/05/2016] [Accepted: 12/06/2016] [Indexed: 11/28/2022]
Abstract
Peripheral heterochromatin in mammalian nuclei is tethered to the nuclear envelope by at least two mechanisms here referred to as the A- and B-tethers. The A-tether includes lamins A/C and additional unknown components presumably INM protein(s) interacting with both lamins A/C and chromatin. The B-tether includes the inner nuclear membrane (INM) protein Lamin B-receptor, which binds B-type lamins and chromatin. Generally, at least one of the tethers is always present in the nuclear envelope of mammalian cells. Deletion of both causes the loss of peripheral heterochromatin and consequently inversion of the entire nuclear architecture, with this occurring naturally in rod photoreceptors of nocturnal mammals. The tethers are differentially utilized during development, regulate gene expression in opposite manners, and play an important role during cell differentiation. Here we aimed to identify the unknown chromatin binding component(s) of the A-tether. We analyzed 10 mouse tissues by immunostaining with antibodies against 7 INM proteins and found that every cell type has specific, although differentially and developmentally regulated, sets of these proteins. In particular, we found that INM protein LEMD2 is concomitantly expressed with A-type lamins in various cell types but is lacking in inverted nuclei of rod cells. Truncation or deletion of Lmna resulted in the downregulation and mislocalization of LEMD2, suggesting that the two proteins interact and pointing at LEMD2 as a potential chromatin binding mediator of the A-tether. Using nuclei of mouse rods as an experimental model lacking peripheral heterochromatin, we expressed a LEMD2 transgene alone or in combination with lamin C in these cells and observed no restoration of peripheral heterochromatin in either case. We conclude that in contrary to the B-tether, the A-tether has a more intricate composition and consists of multiple components that presumably vary, at differing degrees of redundancy, between cell types and differentiation stages.
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Affiliation(s)
- Katharina Thanisch
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Congdi Song
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Dieter Engelkamp
- Transgenic Service Facility, BTE, Franz-Penzoldt-Centre, Friedrich-Alexander-University of Erlangen-Nürnberg, Erwin-Rommel-Str.3, D-91058 Erlangen, Germany
| | - Jeannette Koch
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Audrey Wang
- Institute of Medical Biology, 8A Biomedical Grove and Dept of Biological Sciences, NUS, 138648, Singapore
| | - Einar Hallberg
- Department of Neurochemistry, Stockholm University, Se-106 91 Stockholm, Sweden
| | - Roland Foisner
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Heinrich Leonhardt
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Colin L Stewart
- Institute of Medical Biology, 8A Biomedical Grove and Dept of Biological Sciences, NUS, 138648, Singapore.
| | - Boris Joffe
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Irina Solovei
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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242
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Cho S, Irianto J, Discher DE. Mechanosensing by the nucleus: From pathways to scaling relationships. J Cell Biol 2017; 216:305-315. [PMID: 28043971 PMCID: PMC5294790 DOI: 10.1083/jcb.201610042] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/05/2016] [Accepted: 12/14/2016] [Indexed: 01/01/2023] Open
Abstract
The nucleus is linked mechanically to the extracellular matrix via multiple polymers that transmit forces to the nuclear envelope and into the nuclear interior. Here, we review some of the emerging mechanisms of nuclear mechanosensing, which range from changes in protein conformation and transcription factor localization to chromosome reorganization and membrane dilation up to rupture. Nuclear mechanosensing encompasses biophysically complex pathways that often converge on the main structural proteins of the nucleus, the lamins. We also perform meta-analyses of public transcriptomics and proteomics data, which indicate that some of the mechanosensing pathways relaying signals from the collagen matrix to the nucleus apply to a broad range of species, tissues, and diseases.
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Affiliation(s)
- Sangkyun Cho
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Jerome Irianto
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Dennis E Discher
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
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243
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Abstract
SUMMARYThe nucleoskeleton is an important structural feature of the metazoan nucleus and is involved in the regulation of genome expression and maintenance. The nuclear lamins are intermediate filament proteins that form a peripheral nucleoskeleton in concert with other lamin-associated proteins. Several other proteins normally found in the cytoskeleton have also been identified in the nucleus, but, as will be discussed here, their roles in forming a nucleoskeleton have not been elucidated. Nevertheless, mutations in lamins and lamin-associated proteins cause a spectrum of diseases, making them interesting targets for future research.
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Affiliation(s)
- Stephen A Adam
- Department of Cell and Molecular Biology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611
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244
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Mochizuki R, Tsugama D, Yamazaki M, Fujino K, Masuda K. Identification of candidates for interacting partners of the tail domain of DcNMCP1, a major component of the Daucus carota nuclear lamina-like structure. Nucleus 2017; 8:312-322. [PMID: 28146370 PMCID: PMC5499906 DOI: 10.1080/19491034.2017.1280210] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
NMCP/CRWN (NUCLEAR MATRIX CONSTITUENT PROTEIN/CROWDED NUCLEI) is a major component of a protein fibrous meshwork (lamina-like structure) on the plant inner nuclear membrane. NMCP/CRWN contributes to regulating nuclear shape and nuclear functions. An NMCP/CRWN protein in Daucus carota (DcNMCP1) is localized to the nuclear periphery in interphase cells, and surrounds chromosomes in cells in metaphase and anaphase. The N-terminal region and the C-terminal region of DcNMCP1 are both necessary for localizing DcNMCP1 to the nuclear periphery. Here candidate interacting partners of the amino acid position 975-1053 of DcNMCP1 (T975-1053), which is present in the C-terminal region and contains a conserved sequence that plays a role in localizing DcNMCP1 to the nuclear periphery, are screened for. Arabidopsis thaliana nuclear proteins were subjected to far-Western blotting with GST-fused T975-1053 as a probe, and signals were detected at the positions corresponding to ∼70, ∼40, and ∼18 kDa. These ∼70, ∼40, and ∼18 kDa nuclear proteins were identified by mass spectrometry, and subjected to a yeast 2-hybrid (Y2H) analysis with T975-1053 as bait. In this analysis, the ∼40 kDa protein ARP7, which is a nuclear actin-related protein possibly involved in regulating chromatin structures, was confirmed to interact with T975-1053. Independently of the far-Western blotting, a Y2H screen was performed using T975-1053 as bait. Targeted Y2H assays confirmed that 3 proteins identified in the screen, MYB3, SINAT1, and BIM1, interact with T975-1053. These proteins might have roles in NMCP/CRWN protein-mediated biologic processes.
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Affiliation(s)
- Ryota Mochizuki
- a Laboratory of Crop Physiology, Research Faculty of Agriculture , Hokkaido University , Sapporo-shi , Hokkaido , Japan
| | - Daisuke Tsugama
- a Laboratory of Crop Physiology, Research Faculty of Agriculture , Hokkaido University , Sapporo-shi , Hokkaido , Japan
| | - Michihiro Yamazaki
- a Laboratory of Crop Physiology, Research Faculty of Agriculture , Hokkaido University , Sapporo-shi , Hokkaido , Japan
| | - Kaien Fujino
- a Laboratory of Crop Physiology, Research Faculty of Agriculture , Hokkaido University , Sapporo-shi , Hokkaido , Japan
| | - Kiyoshi Masuda
- a Laboratory of Crop Physiology, Research Faculty of Agriculture , Hokkaido University , Sapporo-shi , Hokkaido , Japan
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245
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Vivante A, Brozgol E, Bronshtein I, Garini Y. Genome organization in the nucleus: From dynamic measurements to a functional model. Methods 2017; 123:128-137. [PMID: 28161540 DOI: 10.1016/j.ymeth.2017.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/27/2016] [Accepted: 01/11/2017] [Indexed: 12/01/2022] Open
Abstract
A biological system is by definition a dynamic environment encompassing kinetic processes that occur at different length scales and time ranges. To explore this type of system, spatial information needs to be acquired at different time scales. This means overcoming significant hurdles, including the need for stable and precise labeling of the required probes and the use of state of the art optical methods. However, to interpret the acquired data, biophysical models that can account for these biological mechanisms need to be developed. The structure and function of a biological system are closely related to its dynamic properties, thus further emphasizing the importance of identifying the rules governing the dynamics that cannot be directly deduced from information on the structure itself. In eukaryotic cells, tens of thousands of genes are packed in the small volume of the nucleus. The genome itself is organized in chromosomes that occupy specific volumes referred to as chromosome territories. This organization is preserved throughout the cell cycle, even though there are no sub-compartments in the nucleus itself. This organization, which is still not fully understood, is crucial for a large number of cellular functions such as gene regulation, DNA breakage repair and error-free cell division. Various techniques are in use today, including imaging, live cell imaging and molecular methods such as chromosome conformation capture (3C) methods to better understand these mechanisms. Live cell imaging methods are becoming well established. These include methods such as Single Particle Tracking (SPT), Continuous Photobleaching (CP), Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Correlation Spectroscopy (FCS) that are currently used for studying proteins, RNA, DNA, gene loci and nuclear bodies. They provide crucial information on its mobility, reorganization, interactions and binding properties. Here we describe how these dynamic methods can be used to gather information on genome organization, its stabilization mechanisms and the proteins that take part in it.
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Affiliation(s)
- Anat Vivante
- Physics Department & Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel
| | - Eugene Brozgol
- Physics Department & Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel
| | - Irena Bronshtein
- Physics Department & Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel
| | - Yuval Garini
- Physics Department & Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel.
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246
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Wu W, Chordia MD, Hart BP, Kumarasinghe ES, Ji MK, Bhargava A, Lawlor MW, Shin JY, Sera F, Homma S, Muchir A, Khire UR, Worman HJ. Macrocyclic MEK1/2 inhibitor with efficacy in a mouse model of cardiomyopathy caused by lamin A/C gene mutation. Bioorg Med Chem 2017; 25:1004-1013. [PMID: 28011205 PMCID: PMC5291759 DOI: 10.1016/j.bmc.2016.12.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 12/06/2016] [Accepted: 12/08/2016] [Indexed: 12/19/2022]
Abstract
Signaling mediated by extracellular signal-regulated kinases 1 and 2 (ERK1/2) is involved in numerous cellular processes. Mitogen-activated protein kinase kinases (MEK1/2) catalyze the phosphorylation of ERK1/2, converting it into an active kinase that regulates the expression of numerous genes and cellular processes. Inhibitors of MEK1/2 have demonstrated preclinical and clinical efficacy in certain cancers and types of cardiomyopathy. We report the synthesis of a novel, allosteric, macrocyclic MEK1/2 inhibitor that potently inhibits ERK1/2 activity in cultured cells and tissues of mice after systemic administration. Mice with dilated cardiomyopathy caused by a lamin A/C gene mutation have abnormally increased cardiac ERK1/2 activity. In these mice, this novel MEK1/2 inhibitor is well tolerated, improves left ventricular systolic function, decreases left ventricular fibrosis, has beneficial effects on skeletal muscle structure and pathology and prolongs survival. The novel MEK1/2 inhibitor described herein may therefore find clinical utility in the treatment of this rare cardiomyopathy, other types of cardiomyopathy and cancers in humans.
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Affiliation(s)
- Wei Wu
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States; Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States
| | - Mahendra D Chordia
- Cheminpharma LLC, 23 Business Park Drive, Branford, CT 06405, United States
| | - Barry P Hart
- AlloMek Therapeutics LLC, 400 Farmington Avenue, Farmington, CT 06032, United States
| | | | - Min K Ji
- Cheminpharma LLC, 23 Business Park Drive, Branford, CT 06405, United States
| | - Ajay Bhargava
- Shakti BioResearch LLC, 1 Bradley Road, Suite 401, Woodbridge, CT 06525, United States
| | - Michael W Lawlor
- Department of Pathology and Laboratory Medicine, Medical College of Wisconsin, 9200 West Wisconsin Avenue, Milwaukee, WI 53226, United States
| | - Ji-Yeon Shin
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States; Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States
| | - Fusako Sera
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States
| | - Shunichi Homma
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States
| | - Antoine Muchir
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States; Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States
| | - Uday R Khire
- Cheminpharma LLC, 23 Business Park Drive, Branford, CT 06405, United States; AlloMek Therapeutics LLC, 400 Farmington Avenue, Farmington, CT 06032, United States.
| | - Howard J Worman
- Department of Medicine, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States; Department of Pathology and Cell Biology, College of Physicians & Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, United States.
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247
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Cofilin Regulates Nuclear Architecture through a Myosin-II Dependent Mechanotransduction Module. Sci Rep 2017; 7:40953. [PMID: 28102353 PMCID: PMC5244421 DOI: 10.1038/srep40953] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 12/14/2016] [Indexed: 01/02/2023] Open
Abstract
Structural features of the nucleus including shape, size and deformability impact its function affecting normal cellular processes such as cell differentiation and pathological conditions such as tumor cell migration. Despite the fact that abnormal nuclear morphology has long been a defining characteristic for diseases such as cancer relatively little is known about the mechanisms that control normal nuclear architecture. Mounting evidence suggests close coupling between F-actin cytoskeletal organization and nuclear morphology however, mechanisms regulating this coupling are lacking. Here we identify that Cofilin/ADF-family F-actin remodeling proteins are essential for normal nuclear structure in different cell types. siRNA mediated silencing of Cofilin/ADF provokes striking nuclear defects including aberrant shapes, nuclear lamina disruption and reductions to peripheral heterochromatin. We provide evidence that these anomalies are primarily due to Rho kinase (ROCK) controlled excessive contractile myosin-II activity and not to elevated F-actin polymerization. Furthermore, we demonstrate a requirement for nuclear envelope LINC (linker of nucleoskeleton and cytoskeleton) complex proteins together with lamin A/C for nuclear aberrations induced by Cofilin/ADF loss. Our study elucidates a pivotal regulatory mechanism responsible for normal nuclear structure and which is expected to fundamentally influence nuclear function.
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248
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Smith ER, Meng Y, Moore R, Tse JD, Xu AG, Xu XX. Nuclear envelope structural proteins facilitate nuclear shape changes accompanying embryonic differentiation and fidelity of gene expression. BMC Cell Biol 2017; 18:8. [PMID: 28088180 PMCID: PMC5237523 DOI: 10.1186/s12860-017-0125-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 01/07/2017] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Nuclear size and shape are specific to a cell type, function, and location, and can serve as indicators of disease and development. We previously found that lamin A/C and associated nuclear envelope structural proteins were upregulated when murine embryonic stem (ES) cells differentiated to primitive endoderm cells. Here we further investigated the morphological changes of nuclei that accompany this differentiation. RESULTS The nuclei of undifferentiated wild type cells were found shaped as flattened, irregular ovals, whereas nuclei of Gata4-positive endoderm cells were more spherical, less flattened, and with a slightly reduced volume. The morphological change was confirmed in the trophectoderm and primitive endoderm lineages of E4.5 blastocysts, compared to larger and more irregularly shaped of the nuclei of the inner cell mass. We established ES cells genetically null for the nuclear lamina proteins lamin A/C or the inner nuclear envelope protein emerin, or compound mutant for both lamin A/C and emerin. ES cells deficient in lamin A/C differentiated to endoderm but less efficiently, and the nuclei remained flattened and failed to condense. The size and shape of emerin-deficient nuclei also remained uncondensed after treatment with RA. The emerin/lamin A/C double knockout ES cells failed to differentiate to endoderm cells, though the nuclei condensed but retained a generally flattened ellipsoid shape. Additionally, ES cells deficient for lamin A/C and/or emerin had compromised ability to undergo endoderm differentiation, where the differentiating cells often exhibited coexpression of pluripotent and differentiation markers, such as Oct3/4 and Gata4, respectively, indicating an infidelity of gene regulation. CONCLUSIONS The results suggest that changes in nuclear size and shape, which are mediated by nuclear envelope structural proteins lamin A/C and/or emerin, also impact gene regulation and lineage differentiation in early embryos. Nevertheless, mice lacking both lamin A/C and emerin were born at the expected frequency, indicating their embryonic development is completed despite the observed protein deficiency.
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Affiliation(s)
- Elizabeth R Smith
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA.
| | - Yue Meng
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA
| | - Robert Moore
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA
| | - Jeffrey D Tse
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA
| | - Arn G Xu
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA
| | - Xiang-Xi Xu
- Department of Cell Biology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Papanicolaou Building, Room 415 [M877] 1550 NW 10th Avenue, Miami, FL, 33136, USA
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249
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Tamiello C, Halder M, Kamps MAF, Baaijens FPT, Broers JLV, Bouten CVC. Cellular strain avoidance is mediated by a functional actin cap - observations in an Lmna-deficient cell model. J Cell Sci 2017; 130:779-790. [PMID: 28062850 DOI: 10.1242/jcs.184838] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 12/29/2016] [Indexed: 01/18/2023] Open
Abstract
In adherent cells, the relevance of a physical mechanotransduction pathway provided by the perinuclear actin cap stress fibers has recently emerged. Here, we investigate the impact of a functional actin cap on the cellular adaptive response to topographical cues and uniaxial cyclic strain. Lmna-deficient fibroblasts are used as a model system because they do not develop an intact actin cap, but predominantly form a basal layer of actin stress fibers underneath the nucleus. We observe that topographical cues induce alignment in both normal and Lmna-deficient fibroblasts, suggesting that the topographical signal transmission occurs independently of the integrity of the actin cap. By contrast, in response to cyclic uniaxial strain, Lmna-deficient cells show a compromised strain avoidance response, which is completely abolished when topographical cues and uniaxial strain are applied along the same direction. These findings point to the importance of an intact and functional actin cap in mediating cellular strain avoidance.
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Affiliation(s)
- Chiara Tamiello
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Maurice Halder
- Department of Molecular Cell Biology, CARIM School for Cardiovascular Diseases, Maastricht University, P.O. Box 616, Maastricht 6200 MD, The Netherlands
| | - Miriam A F Kamps
- Department of Molecular Cell Biology, GROW - School for Oncology & Developmental Biology, Maastricht University, P.O. Box 616, Maastricht 6200 MD, The Netherlands
| | - Frank P T Baaijens
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands.,Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
| | - Jos L V Broers
- Department of Molecular Cell Biology, CARIM School for Cardiovascular Diseases, Maastricht University, P.O. Box 616, Maastricht 6200 MD, The Netherlands
| | - Carlijn V C Bouten
- Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, Eindhoven 5600 MB, The Netherlands
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250
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Stephens AD, Banigan EJ, Adam SA, Goldman RD, Marko JF. Chromatin and lamin A determine two different mechanical response regimes of the cell nucleus. Mol Biol Cell 2017; 28:1984-1996. [PMID: 28057760 PMCID: PMC5541848 DOI: 10.1091/mbc.e16-09-0653] [Citation(s) in RCA: 287] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/04/2016] [Accepted: 12/29/2016] [Indexed: 02/02/2023] Open
Abstract
The cell nucleus must continually resist and respond to intercellular and intracellular mechanical forces to transduce mechanical signals and maintain proper genome organization and expression. Altered nuclear mechanics is associated with many human diseases, including heart disease, progeria, and cancer. Chromatin and nuclear envelope A-type lamin proteins are known to be key nuclear mechanical components perturbed in these diseases, but their distinct mechanical contributions are not known. Here we directly establish the separate roles of chromatin and lamin A/C and show that they determine two distinct mechanical regimes via micromanipulation of single isolated nuclei. Chromatin governs response to small extensions (<3 μm), and euchromatin/heterochromatin levels modulate the stiffness. In contrast, lamin A/C levels control nuclear strain stiffening at large extensions. These results can be understood through simulations of a polymeric shell and cross-linked polymer interior. Our results provide a framework for understanding the differential effects of chromatin and lamin A/C in cell nuclear mechanics and their alterations in disease.
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Affiliation(s)
- Andrew D Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Edward J Banigan
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
| | - Stephen A Adam
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
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