1
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Dutta S, Muraganadan T, Vasudevan M. Evaluation of lamin A/C mechanotransduction under different surface topography in LMNA related muscular dystrophy. Cytoskeleton (Hoboken) 2024. [PMID: 39091017 DOI: 10.1002/cm.21895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024]
Abstract
Most of the single point mutations of the LMNA gene are associated with distinct muscular dystrophies, marked by heterogenous phenotypes but primarily the loss and symmetric weakness of skeletal muscle tissue. The molecular mechanism and phenotype-genotype relationships in these muscular dystrophies are poorly understood. An effort has been here to delineating the adaptation of mechanical inputs into biological response by mutant cells of lamin A associated muscular dystrophy. In this study, we implement engineered smooth and pattern surfaces of particular young modulus to mimic muscle physiological range. Using fluorescence and atomic force microscopy, we present distinct architecture of the actin filament along with abnormally distorted cell and nuclear shape in mutants, which showed a tendency to deviate from wild type cells. Topographic features of pattern surface antagonize the binding of the cell with it. Correspondingly, from the analysis of genome wide expression data in wild type and mutant cells, we report differential expression of the gene products of the structural components of cell adhesion as well as LINC (linkers of nucleoskeleton and cytoskeleton) protein complexes. This study also reveals mis expressed downstream signaling processes in mutant cells, which could potentially lead to onset of the disease upon the application of engineered materials to substitute the role of conventional cues in instilling cellular behaviors in muscular dystrophies. Collectively, these data support the notion that lamin A is essential for proper cellular mechanotransduction from extracellular environment to the genome and impairment of the muscle cell differentiation in the pathogenic mechanism for lamin A associated muscular dystrophy.
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Affiliation(s)
- Subarna Dutta
- Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India
- Theomics International Private Limited, Bengaluru, India
| | - T Muraganadan
- CSIR-Indian Institute of Chemical Biology, Kolkata, India
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2
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Sikder K, Phillips E, Zhong Z, Wang N, Saunders J, Mothy D, Kossenkov A, Schneider T, Nichtova Z, Csordas G, Margulies KB, Choi JC. Perinuclear damage from nuclear envelope deterioration elicits stress responses that contribute to LMNA cardiomyopathy. SCIENCE ADVANCES 2024; 10:eadh0798. [PMID: 38718107 PMCID: PMC11078192 DOI: 10.1126/sciadv.adh0798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/03/2024] [Indexed: 05/12/2024]
Abstract
Mutations in the LMNA gene encoding lamins A/C cause an array of tissue-selective diseases, with the heart being the most commonly affected organ. Despite progress in understanding the perturbations emanating from LMNA mutations, an integrative understanding of the pathogenesis underlying cardiac dysfunction remains elusive. Using a novel conditional deletion model capable of translatome profiling, we observed that cardiomyocyte-specific Lmna deletion in adult mice led to rapid cardiomyopathy with pathological remodeling. Before cardiac dysfunction, Lmna-deleted cardiomyocytes displayed nuclear abnormalities, Golgi dilation/fragmentation, and CREB3-mediated stress activation. Translatome profiling identified MED25 activation, a transcriptional cofactor that regulates Golgi stress. Autophagy is disrupted in the hearts of these mice, which can be recapitulated by disrupting the Golgi. Systemic administration of modulators of autophagy or ER stress significantly delayed cardiac dysfunction and prolonged survival. These studies support a hypothesis wherein stress responses emanating from the perinuclear space contribute to the LMNA cardiomyopathy development.
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Affiliation(s)
- Kunal Sikder
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
| | - Elizabeth Phillips
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
| | - Zhijiu Zhong
- Translational Research and Pathology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Nadan Wang
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
| | - Jasmine Saunders
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
| | - David Mothy
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
| | - Andrew Kossenkov
- Bioinformatics Facility, The Wistar Institute Cancer Center, Philadelphia, PA, USA
| | - Timothy Schneider
- Mitocare, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Zuzana Nichtova
- Mitocare, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Gyorgy Csordas
- Mitocare, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Kenneth B. Margulies
- Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jason C. Choi
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia PA, USA
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3
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Bryson V, Wang C, Zhou Z, Singh K, Volin N, Yildirim E, Rosenberg P. The D84G mutation in STIM1 causes nuclear envelope dysfunction and myopathy in mice. J Clin Invest 2024; 134:e170317. [PMID: 38300705 PMCID: PMC10977986 DOI: 10.1172/jci170317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 01/26/2024] [Indexed: 02/03/2024] Open
Abstract
Stromal interaction molecule 1 (STIM1) is a Ca2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle, where it is best known for its role in store-operated Ca2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focused on a gain-of-function mutation that occurs in humans and mice (STIM1+/D84G mice), in which muscles exhibited constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca2+ transients, SR Ca2+ content, or excitation-contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1+/D84G muscle disrupted nuclear-cytosolic coupling, causing severe derangement in nuclear architecture, DNA damage, and altered lamina A-associated gene expression. Functionally, we found that D84G STIM1 reduced the transfer of Ca2+ from the cytosol to the nucleus in myoblasts, resulting in a reduction of [Ca2+]N. Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca2+ signaling to nuclear stability in skeletal muscle.
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Affiliation(s)
| | - Chaojian Wang
- Department of Medicine
- Duke Cardiovascular Research Center
| | | | | | | | - Eda Yildirim
- Department of Cell Biology
- Duke Cancer Institute, Duke University Medical Center, and
| | - Paul Rosenberg
- Department of Medicine
- Duke Cardiovascular Research Center
- Duke Molecular Physiology Institute, School of Medicine, Durham, North Carolina, USA
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4
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Pande S, Ghosh DK. Nuclear proteostasis imbalance in laminopathy-associated premature aging diseases. FASEB J 2023; 37:e23116. [PMID: 37498235 DOI: 10.1096/fj.202300878r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/15/2023] [Accepted: 07/13/2023] [Indexed: 07/28/2023]
Abstract
Laminopathies are a group of rare genetic disorders with heterogeneous clinical phenotypes such as premature aging, cardiomyopathy, lipodystrophy, muscular dystrophy, microcephaly, epilepsy, and so on. The cellular phenomena associated with laminopathy invariably show disruption of nucleoskeleton of lamina due to deregulated expression, localization, function, and interaction of mutant lamin proteins. Impaired spatial and temporal tethering of lamin proteins to the lamina or nucleoplasmic aggregation of lamins are the primary molecular events that can trigger nuclear proteotoxicity by modulating differential protein-protein interactions, sequestering quality control proteins, and initiating a cascade of abnormal post-translational modifications. Clearly, laminopathic cells exhibit moderate to high nuclear proteotoxicity, raising the question of whether an imbalance in nuclear proteostasis is involved in laminopathic diseases, particularly in diseases of early aging such as HGPS and laminopathy-associated premature aging. Here, we review nuclear proteostasis and its deregulation in the context of lamin proteins and laminopathies.
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Affiliation(s)
- Shruti Pande
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
| | - Debasish Kumar Ghosh
- Enteric Disease Division, Department of Microbiology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, India
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5
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Sikder K, Phillips E, Zhong Z, Wang N, Saunders J, Mothy D, Kossenkov A, Schneider T, Nichtova Z, Csordas G, Margulies KB, Choi JC. Perinuclear damage from nuclear envelope deterioration elicits stress responses that contribute to LMNA cardiomyopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.14.528563. [PMID: 36824975 PMCID: PMC9949050 DOI: 10.1101/2023.02.14.528563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Mutations in the LMNA gene encoding nuclear lamins A/C cause a diverse array of tissue-selective diseases, with the heart being the most commonly affected organ. Despite progress in understanding the molecular perturbations emanating from LMNA mutations, an integrative understanding of the pathogenesis leading to cardiac dysfunction remains elusive. Using a novel cell-type specific Lmna deletion mouse model capable of translatome profiling, we found that cardiomyocyte-specific Lmna deletion in adult mice led to rapid cardiomyopathy with pathological remodeling. Prior to the onset of cardiac dysfunction, lamin A/C-depleted cardiomyocytes displayed nuclear envelope deterioration, golgi dilation/fragmentation, and CREB3-mediated golgi stress activation. Translatome profiling identified upregulation of Med25, a transcriptional co-factor that can selectively dampen UPR axes. Autophagy is disrupted in the hearts of these mice, which can be recapitulated by disrupting the golgi or inducing nuclear damage by increased matrix stiffness. Systemic administration of pharmacological modulators of autophagy or ER stress significantly improved the cardiac function. These studies support a hypothesis wherein stress responses emanating from the perinuclear space contribute to the development of LMNA cardiomyopathy. Teaser Interplay of stress responses underlying the development of LMNA cardiomyopathy.
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6
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Bryson V, Wang C, Zhou Z, Singh K, Volin N, Yildirim E, Rosenberg P. The D84G mutation in STIM1 causes nuclear envelope dysfunction and myopathy in mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.03.539279. [PMID: 37205564 PMCID: PMC10187192 DOI: 10.1101/2023.05.03.539279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Stromal interaction molecule 1 (STIM1) is a Ca 2+ sensor located in the sarcoplasmic reticulum (SR) of skeletal muscle where it is best known for its role in store operated Ca 2+ entry (SOCE). Genetic syndromes resulting from STIM1 mutations are recognized as a cause of muscle weakness and atrophy. Here, we focus on a gain of function mutation that occurs in humans and mice (STIM1 +/D84G mice) where muscles exhibit constitutive SOCE. Unexpectedly, this constitutive SOCE did not affect global Ca 2+ transients, SR Ca 2+ content or excitation contraction coupling (ECC) and was therefore unlikely to underlie the reduced muscle mass and weakness observed in these mice. Instead, we demonstrate that the presence of D84G STIM1 in the nuclear envelope of STIM1 +/D84G muscle disrupts nuclear-cytosolic coupling causing severe derangement in nuclear architecture, DNA damage, and altered lamina A associated gene expression. Functionally, we found D84G STIM1 reduced the transfer of Ca 2+ from the cytosol to the nucleus in myoblasts resulting in a reduction of [Ca 2+ ] N . Taken together, we propose a novel role for STIM1 in the nuclear envelope that links Ca 2+ signaling to nuclear stability in skeletal muscle.
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7
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Wang C, Ramahdita G, Genin G, Huebsch N, Ma Z. Dynamic mechanobiology of cardiac cells and tissues: Current status and future perspective. BIOPHYSICS REVIEWS 2023; 4:011314. [PMID: 37008887 PMCID: PMC10062054 DOI: 10.1063/5.0141269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/08/2023] [Indexed: 03/31/2023]
Abstract
Mechanical forces impact cardiac cells and tissues over their entire lifespan, from development to growth and eventually to pathophysiology. However, the mechanobiological pathways that drive cell and tissue responses to mechanical forces are only now beginning to be understood, due in part to the challenges in replicating the evolving dynamic microenvironments of cardiac cells and tissues in a laboratory setting. Although many in vitro cardiac models have been established to provide specific stiffness, topography, or viscoelasticity to cardiac cells and tissues via biomaterial scaffolds or external stimuli, technologies for presenting time-evolving mechanical microenvironments have only recently been developed. In this review, we summarize the range of in vitro platforms that have been used for cardiac mechanobiological studies. We provide a comprehensive review on phenotypic and molecular changes of cardiomyocytes in response to these environments, with a focus on how dynamic mechanical cues are transduced and deciphered. We conclude with our vision of how these findings will help to define the baseline of heart pathology and of how these in vitro systems will potentially serve to improve the development of therapies for heart diseases.
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Affiliation(s)
| | - Ghiska Ramahdita
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | | | | | - Zhen Ma
- Authors to whom correspondence should be addressed: and
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8
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Virtanen L, Holm E, Halme M, West G, Lindholm F, Gullmets J, Irjala J, Heliö T, Padzik A, Meinander A, Eriksson JE, Taimen P. Lamin A/C phosphorylation at serine 22 is a conserved heat shock response to regulate nuclear adaptation during stress. J Cell Sci 2023; 136:289469. [PMID: 36695453 PMCID: PMC10022683 DOI: 10.1242/jcs.259788] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 01/16/2023] [Indexed: 01/26/2023] Open
Abstract
The heat shock (HS) response is crucial for cell survival in harmful environments. Nuclear lamin A/C, encoded by the LMNA gene, contributes towards altered gene expression during HS, but the underlying mechanisms are poorly understood. Here, we show that upon HS, lamin A/C was reversibly phosphorylated at serine 22 in concert with HSF1 activation in human cells, mouse cells and Drosophila melanogaster in vivo. Consequently, the phosphorylation facilitated nucleoplasmic localization of lamin A/C and nuclear sphericity in response to HS. Interestingly, lamin A/C knock-out cells showed deformed nuclei after HS and were rescued by ectopic expression of wild-type lamin A, but not by a phosphomimetic (S22D) lamin A mutant. Furthermore, HS triggered concurrent downregulation of lamina-associated protein 2α (Lap2α, encoded by TMPO) in wild-type lamin A/C-expressing cells, but a similar response was perturbed in lamin A/C knock-out cells and in LMNA mutant patient fibroblasts, which showed impaired cell cycle arrest under HS and compromised survival at recovery. Taken together, our results suggest that the altered phosphorylation stoichiometry of lamin A/C provides an evolutionarily conserved mechanism to regulate lamina structure and serve nuclear adaptation and cell survival during HS.
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Affiliation(s)
- Laura Virtanen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Emilia Holm
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Mona Halme
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Gun West
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Fanny Lindholm
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Josef Gullmets
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland.,Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - Juho Irjala
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland
| | - Tiina Heliö
- Heart and Lung Center, Helsinki University Hospital and University of Helsinki, 00029 Helsinki, Finland
| | - Artur Padzik
- Genome Editing Core, Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Annika Meinander
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland
| | - John E Eriksson
- Faculty of Science and Engineering, Åbo Akademi University, 20520 Turku, Finland.,Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Pekka Taimen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, 20520 Turku, Finland.,Department of Pathology, Turku University Hospital, 20520 Turku, Finland
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9
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West G, Turunen M, Aalto A, Virtanen L, Li SP, Heliö T, Meinander A, Taimen P. A heterozygous p.S143P mutation in LMNA associates with proteasome dysfunction and enhanced autophagy-mediated degradation of mutant lamins A and C. Front Cell Dev Biol 2022; 10:932983. [PMID: 36111332 PMCID: PMC9468711 DOI: 10.3389/fcell.2022.932983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/27/2022] [Indexed: 01/09/2023] Open
Abstract
Lamins A and C are nuclear intermediate filament proteins that form a proteinaceous meshwork called lamina beneath the inner nuclear membrane. Mutations in the LMNA gene encoding lamins A and C cause a heterogenous group of inherited degenerative diseases known as laminopathies. Previous studies have revealed altered cell signaling pathways in lamin-mutant patient cells, but little is known about the fate of mutant lamins A and C within the cells. Here, we analyzed the turnover of lamins A and C in cells derived from a dilated cardiomyopathy patient with a heterozygous p.S143P mutation in LMNA. We found that transcriptional activation and mRNA levels of LMNA are increased in the primary patient fibroblasts, but the protein levels of lamins A and C remain equal in control and patient cells because of a meticulous interplay between autophagy and the ubiquitin-proteasome system (UPS). Both endogenous and ectopic expression of p.S143P lamins A and C cause significantly reduced activity of UPS and an accumulation of K48-ubiquitin chains in the nucleus. Furthermore, K48-ubiquitinated lamins A and C are degraded by compensatory enhanced autophagy, as shown by increased autophagosome formation and binding of lamins A and C to microtubule-associated protein 1A/1B-light chain 3. Finally, chaperone 4-PBA augmented protein degradation by restoring UPS activity as well as autophagy in the patient cells. In summary, our results suggest that the p.S143P-mutant lamins A and C have overloading and deleterious effects on protein degradation machinery and pharmacological interventions with compounds enhancing protein degradation may be beneficial for cell homeostasis.
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Affiliation(s)
- Gun West
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, Turku, Finland,InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland
| | - Minttu Turunen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, Turku, Finland,InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland
| | - Anna Aalto
- InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland,Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Laura Virtanen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, Turku, Finland,InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland
| | - Song-Ping Li
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, Turku, Finland,InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland
| | - Tiina Heliö
- Heart and Lung Center Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Annika Meinander
- InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland,Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Pekka Taimen
- Institute of Biomedicine and FICAN West Cancer Centre, University of Turku, Turku, Finland,InFLAMES Research Flagship Center, University of Turku and Åbo Akademi University, Turku, Finland,Department of Pathology, Laboratory Division, Turku University Hospital, Turku, Finland,*Correspondence: Pekka Taimen,
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10
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C9orf72 dipeptides disrupt the nucleocytoplasmic transport machinery and cause TDP-43 mislocalisation to the cytoplasm. Sci Rep 2022; 12:4799. [PMID: 35314728 PMCID: PMC8938440 DOI: 10.1038/s41598-022-08724-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 03/01/2022] [Indexed: 12/03/2022] Open
Abstract
A repeat expansion in C9orf72 is the major cause of both frontotemporal dementia and amyotrophic lateral sclerosis, accounting for approximately 1 in 12 cases of either disease. The expansion is translated to produce five dipeptide repeat proteins (DPRs) which aggregate in patient brain and are toxic in numerous models, though the mechanisms underlying this toxicity are poorly understood. Recent studies highlight nucleocytoplasmic transport impairments as a potential mechanism underlying neurodegeneration in C9orf72-linked disease, although the contribution of DPRs to this remains unclear. We expressed DPRs in HeLa cells, in the absence of repeat RNA. Crucially, we expressed DPRs at repeat-lengths found in patients (> 1000 units), ensuring our findings were relevant to disease. Immunofluorescence imaging was used to investigate the impact of each DPR on the nucleus, nucleocytoplasmic transport machinery and TDP-43 localisation. DPRs impaired the structural integrity of the nucleus, causing nuclear membrane disruption and misshapen nuclei. Ran and RanGAP, two proteins required for nucleocytoplasmic transport, were also mislocalised in DPR-expressing cells. Furthermore, DPRs triggered mislocalisation of TDP-43 to the cytoplasm, and this occurred in the same cells as Ran and RanGAP mislocalisation, suggesting a potential link between DPRs, nucleocytoplasmic transport impairments and TDP-43 pathology.
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11
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Alonso-Barroso E, Pérez B, Desviat LR, Richard E. Cardiomyocytes Derived from Induced Pluripotent Stem Cells as a Disease Model for Propionic Acidemia. Int J Mol Sci 2021; 22:ijms22031161. [PMID: 33503868 PMCID: PMC7865492 DOI: 10.3390/ijms22031161] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/20/2021] [Accepted: 01/21/2021] [Indexed: 12/13/2022] Open
Abstract
Propionic acidemia (PA), one of the most frequent life-threatening organic acidemias, is caused by mutations in either the PCCA or PCCB genes encoding both subunits of the mitochondrial propionyl-CoA carboxylase (PCC) enzyme. Cardiac alterations (hypertrophy, dilated cardiomyopathy, long QT) are one of the major causes of mortality in patients surviving the neonatal period. To overcome limitations of current cellular models of PA, we generated induced pluripotent stem cells (iPSCs) from a PA patient with defects in the PCCA gene, and successfully differentiated them into cardiomyocytes. PCCA iPSC-derived cardiomyocytes exhibited reduced oxygen consumption, an accumulation of residual bodies and lipid droplets, and increased ribosomal biogenesis. Furthermore, we found increased protein levels of HERP, GRP78, GRP75, SIG-1R and MFN2, suggesting endoplasmic reticulum stress and calcium perturbations in these cells. We also analyzed a series of heart-enriched miRNAs previously found deregulated in the heart tissue of a PA murine model and confirmed their altered expression. Our novel results show that PA iPSC-cardiomyocytes represent a promising model for investigating the pathological mechanisms underlying PA cardiomyopathies, also serving as an ex vivo platform for therapeutic evaluation.
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Affiliation(s)
- Esmeralda Alonso-Barroso
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.A.-B.); (B.P.); (L.R.D.)
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), 28049 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria Hospital La Paz (IdiPaz), ISCIII, 28029 Madrid, Spain
| | - Belén Pérez
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.A.-B.); (B.P.); (L.R.D.)
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), 28049 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria Hospital La Paz (IdiPaz), ISCIII, 28029 Madrid, Spain
| | - Lourdes Ruiz Desviat
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.A.-B.); (B.P.); (L.R.D.)
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), 28049 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria Hospital La Paz (IdiPaz), ISCIII, 28029 Madrid, Spain
| | - Eva Richard
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, Universidad Autónoma de Madrid, 28049 Madrid, Spain; (E.A.-B.); (B.P.); (L.R.D.)
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), 28049 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), ISCIII, 28029 Madrid, Spain
- Instituto de Investigación Sanitaria Hospital La Paz (IdiPaz), ISCIII, 28029 Madrid, Spain
- Correspondence:
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12
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Kumar VK, Lackey A, Snyder J, Karhadkar S, Rao AD, DiCarlo A, Sato PY. Mitochondrial Membrane Intracellular Communication in Healthy and Diseased Myocardium. Front Cell Dev Biol 2020; 8:609241. [PMID: 33425917 PMCID: PMC7786191 DOI: 10.3389/fcell.2020.609241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/19/2020] [Indexed: 12/24/2022] Open
Abstract
Research efforts in the twenty-first century have been paramount to the discovery and development of novel pharmacological treatments in a variety of diseases resulting in improved life expectancy. Yet, cardiac disease remains a leading cause of morbidity and mortality worldwide. Over time, there has been an expansion in conditions such as atrial fibrillation (AF) and heart failure (HF). Although past research has elucidated specific pathways that participate in the development of distinct cardiac pathologies, the exact mechanisms of action leading to disease remain to be fully characterized. Protein turnover and cellular bioenergetics are integral components of cardiac diseases, highlighting the importance of mitochondria and endoplasmic reticulum (ER) in driving cellular homeostasis. More specifically, the interactions between mitochondria and ER are crucial to calcium signaling, apoptosis induction, autophagy, and lipid biosynthesis. Here, we summarize mitochondrial and ER functions and physical interactions in healthy physiological states. We then transition to perturbations that occur in response to pathophysiological challenges and how this alters mitochondrial–ER and other intracellular organelle interactions. Finally, we discuss lifestyle interventions and innovative therapeutic targets that may be used to restore beneficial mitochondrial and ER interactions, thereby improving cardiac function.
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Affiliation(s)
- Vishnu K Kumar
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Atreju Lackey
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Jonathan Snyder
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Sunil Karhadkar
- Department of Surgery, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Ajay D Rao
- Section of Endocrinology, Diabetes and Metabolism, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States.,Center for Metabolic Disease Research, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Antonio DiCarlo
- Department of Surgery, Temple University Lewis Katz School of Medicine, Philadelphia, PA, United States
| | - Priscila Y Sato
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA, United States
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13
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Piccus R, Brayson D. The nuclear envelope: LINCing tissue mechanics to genome regulation in cardiac and skeletal muscle. Biol Lett 2020; 16:20200302. [PMID: 32634376 DOI: 10.1098/rsbl.2020.0302] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Regulation of the genome is viewed through the prism of gene expression, DNA replication and DNA repair as controlled through transcription, chromatin compartmentalisation and recruitment of repair factors by enzymes such as DNA polymerases, ligases, acetylases, methylases and cyclin-dependent kinases. However, recent advances in the field of muscle cell physiology have also shown a compelling role for 'outside-in' biophysical control of genomic material through mechanotransduction. The crucial hub that transduces these biophysical signals is called the Linker of Nucleoskeleton and Cytoskeleton (LINC). This complex is embedded across the nuclear envelope, which separates the nucleus from the cytoplasm. How the LINC complex operates to mechanically regulate the many functions of DNA is becoming increasingly clear, and recent advances have provided exciting insight into how this occurs in cells from mechanically activated tissues such as skeletal and cardiac muscle. Nevertheless, there are still some notable shortcomings in our understanding of these processes and resolving these will likely help us understand how muscle diseases manifest at the level of the genome.
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Affiliation(s)
- Rachel Piccus
- Centre for Human and Applied Physiological Sciences, King's College London, London SE1 1UL, UK
| | - Daniel Brayson
- School of Cardiovascular Medicine and Sciences, King's College London, London SE5 9NU, UK.,Molecular Neurosciences, UCL Great Ormond Street Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK
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14
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An Omics View of Emery-Dreifuss Muscular Dystrophy. J Pers Med 2020; 10:jpm10020050. [PMID: 32549253 PMCID: PMC7354601 DOI: 10.3390/jpm10020050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/08/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023] Open
Abstract
Recent progress in Omics technologies has started to empower personalized healthcare development at a thorough biomolecular level. Omics have subsidized medical breakthroughs that have started to enter clinical proceedings. The use of this scientific know-how has surfaced as a way to provide a more far-reaching view of the biological mechanisms behind diseases. This review will focus on the discoveries made using Omics and the utility of these approaches for Emery–Dreifuss muscular dystrophy.
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15
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Li J, Zhang D, Brundel BJJM, Wiersma M. Imbalance of ER and Mitochondria Interactions: Prelude to Cardiac Ageing and Disease? Cells 2019; 8:cells8121617. [PMID: 31842269 PMCID: PMC6952992 DOI: 10.3390/cells8121617] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/06/2019] [Accepted: 12/10/2019] [Indexed: 12/19/2022] Open
Abstract
Cardiac disease is still the leading cause of morbidity and mortality worldwide, despite some exciting and innovative improvements in clinical management. In particular, atrial fibrillation (AF) and heart failure show a steep increase in incidence and healthcare costs due to the ageing population. Although research revealed novel insights in pathways driving cardiac disease, the exact underlying mechanisms have not been uncovered so far. Emerging evidence indicates that derailed proteostasis (i.e., the homeostasis of protein expression, function and clearance) is a central component driving cardiac disease. Within proteostasis derailment, key roles for endoplasmic reticulum (ER) and mitochondrial stress have been uncovered. Here, we describe the concept of ER and mitochondrial stress and the role of interactions between the ER and mitochondria, discuss how imbalance in the interactions fuels cardiac ageing and cardiac disease (including AF), and finally assess the potential of drugs directed at conserving the interaction as an innovative therapeutic target to improve cardiac function.
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Affiliation(s)
- Jin Li
- Correspondence: (J.L.); (M.W.)
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16
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Modeling of LMNA-Related Dilated Cardiomyopathy Using Human Induced Pluripotent Stem Cells. Cells 2019; 8:cells8060594. [PMID: 31208058 PMCID: PMC6627421 DOI: 10.3390/cells8060594] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 12/31/2022] Open
Abstract
Dilated cardiomyopathy (DCM) is one of the leading causes of heart failure and heart transplantation. A portion of familial DCM is due to mutations in the LMNA gene encoding the nuclear lamina proteins lamin A and C and without adequate treatment these patients have a poor prognosis. To get better insights into pathobiology behind this disease, we focused on modeling LMNA-related DCM using human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CM). Primary skin fibroblasts from DCM patients carrying the most prevalent Finnish founder mutation (p.S143P) in LMNA were reprogrammed into hiPSCs and further differentiated into cardiomyocytes (CMs). The cellular structure, functionality as well as gene and protein expression were assessed in detail. While mutant hiPSC-CMs presented virtually normal sarcomere structure under normoxia, dramatic sarcomere damage and an increased sensitivity to cellular stress was observed after hypoxia. A detailed electrophysiological evaluation revealed bradyarrhythmia and increased occurrence of arrhythmias in mutant hiPSC-CMs on β-adrenergic stimulation. Mutant hiPSC-CMs also showed increased sensitivity to hypoxia on microelectrode array and altered Ca2+ dynamics. Taken together, p.S143P hiPSC-CM model mimics hallmarks of LMNA-related DCM and provides a useful tool to study the underlying cellular mechanisms of accelerated cardiac degeneration in this disease.
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17
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Asatryan B, Medeiros-Domingo A. Molecular and genetic insights into progressive cardiac conduction disease. Europace 2019; 21:1145-1158. [DOI: 10.1093/europace/euz109] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 03/27/2019] [Indexed: 12/14/2022] Open
Abstract
Abstract
Progressive cardiac conduction disease (PCCD) is often a primarily genetic disorder, with clinical and genetic overlaps with other inherited cardiac and metabolic diseases. A number of genes have been implicated in PCCD pathogenesis with or without structural heart disease or systemic manifestations. Precise genetic diagnosis contributes to risk stratification, better selection of specific therapy and allows familiar cascade screening. Cardiologists should be aware of the different phenotypes emerging from different gene-mutations and the potential risk of sudden cardiac death. Genetic forms of PCCD often overlap or coexist with other inherited heart diseases or manifest in the context of multisystem syndromes. Despite the significant advances in the knowledge of the genetic architecture of PCCD and overlapping diseases, in a measurable fraction of PCCD cases, including in familial clustering of disease, investigations of known cardiac disease-associated genes fail to reveal the underlying substrate, suggesting that new causal genes are yet to be discovered. Here, we provide insight into genetics and molecular mechanisms of PCCD and related diseases. We also highlight the phenotypic overlaps of PCCD with other inherited cardiac and metabolic diseases, present unmet challenges in clinical practice, and summarize the available therapeutic options for affected patients.
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Affiliation(s)
- Babken Asatryan
- Department of Cardiology, Inselspital, Bern University Hospital, Freiburgstrasse 8, Bern, Switzerland
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18
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Kittisopikul M, Virtanen L, Taimen P, Goldman RD. Quantitative Analysis of Nuclear Lamins Imaged by Super-Resolution Light Microscopy. Cells 2019; 8:E361. [PMID: 31003483 PMCID: PMC6524165 DOI: 10.3390/cells8040361] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 04/13/2019] [Accepted: 04/14/2019] [Indexed: 11/20/2022] Open
Abstract
The nuclear lamina consists of a dense fibrous meshwork of nuclear lamins, Type V intermediate filaments, and is ~14 nm thick according to recent cryo-electron tomography studies. Recent advances in light microscopy have extended the resolution to a scale allowing for the fine structure of the lamina to be imaged in the context of the whole nucleus. We review quantitative approaches to analyze the imaging data of the nuclear lamina as acquired by structured illumination microscopy (SIM) and single molecule localization microscopy (SMLM), as well as the requisite cell preparation techniques. In particular, we discuss the application of steerable filters and graph-based methods to segment the structure of the four mammalian lamin isoforms (A, C, B1, and B2) and extract quantitative information.
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Affiliation(s)
- Mark Kittisopikul
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| | - Laura Virtanen
- Institute of Biomedicine, Research Center for Cancer, Infections and Immunity, University of Turku, 20520 Turku, Finland.
| | - Pekka Taimen
- Institute of Biomedicine, Research Center for Cancer, Infections and Immunity, University of Turku, 20520 Turku, Finland.
- Department of Pathology, Turku University Hospital, 20520 Turku, Finland.
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
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19
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Al-Saaidi RA, Rasmussen TB, Birkler RID, Palmfeldt J, Beqqali A, Pinto YM, Nissen PH, Baandrup U, Mølgaard H, Hey TM, Eiskjaer H, Bross P, Mogensen J. The clinical outcome of LMNA missense mutations can be associated with the amount of mutated protein in the nuclear envelope. Eur J Heart Fail 2018; 20:1404-1412. [PMID: 29943882 DOI: 10.1002/ejhf.1241] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/18/2018] [Accepted: 05/21/2018] [Indexed: 12/17/2022] Open
Abstract
AIMS Lamin A/C mutations are generally believed to be associated with a severe prognosis. The aim of this study was to investigate disease expression in three affected families carrying different LMNA missense mutations. Furthermore, the potential molecular disease mechanisms of the mutations were investigated in fibroblasts obtained from mutation carriers. METHODS AND RESULTS A LMNA-p.Arg216Cys missense mutation was identified in a large family with 36 mutation carriers. Disease expression was unusual with a late onset and a favourable prognosis. Two smaller families with severe disease expression were shown to carry a LMNA-p.Arg471Cys and LMNA-p.Arg471His mutation, respectively. LMNA gene and protein expression was investigated in eight different mutation carriers by quantitative reverse transcriptase polymerase chain reaction, Western blotting, immunohistochemistry, and protein mass spectrometry. The results showed that all mutation carriers incorporated mutated lamin protein into the nuclear envelope. Interestingly, the ratio of mutated to wild-type protein was only 30:70 in LMNA-p.Arg216Cys carriers with a favourable prognosis while LMNA-p.Arg471Cys and LMNA-p.Arg471His carriers with a more severe outcome expressed significantly more of the mutated protein by a ratio of 50:50. CONCLUSION The clinical findings indicated that some LMNA mutations may be associated with a favourable prognosis and a low risk of sudden death. Protein expression studies suggested that a severe outcome was associated with the expression of high amounts of mutated protein. These findings may prove to be helpful in counselling and risk assessment of LMNA families.
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Affiliation(s)
- Rasha A Al-Saaidi
- Research Unit for Molecular Medicine, Aarhus University and University Hospital, Aarhus, Denmark
| | | | - Rune I D Birkler
- Research Unit for Molecular Medicine, Aarhus University and University Hospital, Aarhus, Denmark
| | - Johan Palmfeldt
- Research Unit for Molecular Medicine, Aarhus University and University Hospital, Aarhus, Denmark
| | - Abdelaziz Beqqali
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
| | - Yigal M Pinto
- Heart Failure Research Center, Academic Medical Center, Amsterdam, The Netherlands
| | - Peter H Nissen
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
| | - Ulrik Baandrup
- Centre for Clinical Research, North Denmark Regional Hospital/Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | - Henning Mølgaard
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Thomas M Hey
- Department of Cardiology, Odense University Hospital, Odense, Denmark
| | - Hans Eiskjaer
- Department of Cardiology, Aarhus University Hospital, Aarhus, Denmark
| | - Peter Bross
- Research Unit for Molecular Medicine, Aarhus University and University Hospital, Aarhus, Denmark
| | - Jens Mogensen
- Department of Cardiology, Odense University Hospital, Odense, Denmark
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20
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Elenbaas JS, Cunha JB, Azuero-Dajud R, Nelson B, Oral EA, Williams JA, Stewart CL, Omary MB. Lamin A/C Maintains Exocrine Pancreas Homeostasis by Regulating Stability of RB and Activity of E2F. Gastroenterology 2018; 154:1625-1629.e8. [PMID: 29366840 PMCID: PMC5927841 DOI: 10.1053/j.gastro.2018.01.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/29/2017] [Accepted: 01/09/2018] [Indexed: 12/18/2022]
Abstract
Lamins have important roles in nuclear structure and cell signaling. Several diseases are associated with mutations in the lamin A/C gene (LMNA in humans). Patients with familial partial lipodystrophy caused by LMNA mutations develop pancreatitis, but lamin function in the pancreas and how these mutations affect pancreatic regulation are unknown. We generated mice with inducible exocrine pancreas-specific disruption of Lmna and showed that LMNA is lost from most exocrine pancreas cells. LMNA-knockout pancreata develop endoplasmic reticulum stress with loss of acinar cell markers, increased autophagy, apoptosis, and cell proliferation, compared to CreERT2- mice (littermate controls). Disruption of Lmna led to a phenotype that resembled chronic pancreatitis, with increased Sirius Red staining and α-smooth muscle actin in male LMNA-knockout mice compared to littermate males, but not in female mice. LMNA-knockout pancreata have reduced levels of RB and activation of E2F, based on increased expression of E2F target genes. Therefore, lamins maintain pancreatic homeostasis by regulating RB stability and E2F activity.
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Affiliation(s)
- Jared S. Elenbaas
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Juliana Bragazzi Cunha
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Rodrigo Azuero-Dajud
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Bradley Nelson
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Elif A. Oral
- Division of Metabolism, Endocrinology and Diabetes Division, Brehm Center for Diabetes, University of Michigan, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - John A. Williams
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan,Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | | | - 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,To whom correspondence should be addressed: University of Michigan Medical School, Department of Molecular & Integrative Physiology, 7744 Medical Science Bldg.II, 1137 East Catherine St., Ann Arbor, MI 48109-5622.
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21
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Bhattacharjee P, Dasgupta D, Sengupta K. DCM associated LMNA mutations cause distortions in lamina structure and assembly. Biochim Biophys Acta Gen Subj 2017; 1861:2598-2608. [PMID: 28844980 DOI: 10.1016/j.bbagen.2017.08.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/01/2017] [Accepted: 08/11/2017] [Indexed: 11/22/2022]
Abstract
BACKGROUND A and B-type lamins are integral scaffolding components of the nuclear lamina which impart rigidity and shape to all metazoan nuclei. Over 450 mutations in A-type lamins are associated with 16 human diseases including dilated cardiomyopathy (DCM). Here, we show that DCM mutants perturb the self-association of lamin A (LA) and it's binding with lamin B1 (LB1). METHODS We used confocal and superresolution microscopy (NSIM) to study the effect of LA mutants on the nuclear lamina. We further used circular dichroism, fluorescence spectroscopy and isothermal titration calorimetry (ITC) to probe the structural modulations, self-association and heteropolymeric association of mutant LA. RESULTS Transfection of mutants in cultured cell lines result in the formation of nuclear aggregates of varied size and distribution. Endogenous LB1 is sequestered into these aggregates. This is consistent with the ten-fold increase in association constant of the mutant proteins compared to the wild type. These mutants exhibit differential heterotypic interaction with LB1, along with significant secondary and tertiary structural alterations of the interacting proteins. Thermodynamic studies demonstrate that the mutants bind to LB1 with different stoichiometry, affinity and energetics. CONCLUSIONS In this report we show that increased self-association propensity of mutant LA modulates the LA-LB1 interaction and precludes the formation of an otherwise uniform laminar network. GENERAL SIGNIFICANCE Our results might highlight the role of homotypic and heterotypic interactions of LA in the pathogenesis of DCM and hence laminopathies in the broader sense.
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Affiliation(s)
- Pritha Bhattacharjee
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India
| | - Dipak Dasgupta
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
| | - Kaushik Sengupta
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064, India.
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22
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Abstract
The nuclear lamina is a critical structural domain for the maintenance of genomic stability and whole-cell mechanics. Mutations in the LMNA gene, which encodes nuclear A-type lamins lead to the disruption of these key cellular functions, resulting in a number of devastating diseases known as laminopathies. Cardiomyopathy is a common laminopathy and is highly penetrant with poor prognosis. To date, cell mechanical instability and dysregulation of gene expression have been proposed as the main mechanisms driving cardiac dysfunction, and indeed discoveries in these areas have provided some promising leads in terms of therapeutics. However, important questions remain unanswered regarding the role of lamin A dysfunction in the heart, including a potential role for the toxicity of lamin A precursors in LMNA cardiomyopathy, which has yet to be rigorously investigated.
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Affiliation(s)
- Daniel Brayson
- a King's College London, The James Black Centre , London , United Kingdom
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23
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The effect of the lamin A and its mutants on nuclear structure, cell proliferation, protein stability, and mobility in embryonic cells. Chromosoma 2016; 126:501-517. [PMID: 27534416 PMCID: PMC5509783 DOI: 10.1007/s00412-016-0610-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 07/11/2016] [Accepted: 08/02/2016] [Indexed: 01/26/2023]
Abstract
LMNA gene encodes for nuclear intermediate filament proteins lamin A/C. Mutations in this gene lead to a spectrum of genetic disorders, collectively referred to as laminopathies. Lamin A/C are widely expressed in most differentiated somatic cells but not in early embryos and some undifferentiated cells. To investigate the role of lamin A/C in cell phenotype maintenance and differentiation, which could be a determinant of the pathogenesis of laminopathies, we examined the role played by exogenous lamin A and its mutants in differentiated cell lines (HeLa, NHDF) and less-differentiated HEK 293 cells. We introduced exogenous wild-type and mutated (H222P, L263P, E358K D446V, and ∆50) lamin A into different cell types and analyzed proteins’ impact on proliferation, protein mobility, and endogenous nuclear envelope protein distribution. The mutants give rise to a broad spectrum of nuclear phenotypes and relocate lamin C. The mutations ∆50 and D446V enhance proliferation in comparison to wild-type lamin A and control cells, but no changes in exogenous protein mobility measured by FRAP were observed. Interestingly, although transcripts for lamins A and C are at similar level in HEK 293 cells, only lamin C protein is detected in western blots. Also, exogenous lamin A and its mutants, when expressed in HEK 293 cells underwent posttranscriptional processing. Overall, our results provide new insight into the maintenance of lamin A in less-differentiated cells. Embryonic cells are very sensitive to lamin A imbalance, and its upregulation disturbs lamin C, which may influence gene expression and many regulatory pathways.
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