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Tiwari V, Alam MJ, Bhatia M, Navya M, Banerjee SK. The structure and function of lamin A/C: Special focus on cardiomyopathy and therapeutic interventions. Life Sci 2024; 341:122489. [PMID: 38340979 DOI: 10.1016/j.lfs.2024.122489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 01/21/2024] [Accepted: 02/03/2024] [Indexed: 02/12/2024]
Abstract
Lamins are inner nuclear membrane proteins that belong to the intermediate filament family. Lamin A/C lie adjacent to the heterochromatin structure in polymer form, providing skeletal to the nucleus. Based on the localization, lamin A/C provides nuclear stability and cytoskeleton to the nucleus and modulates chromatin organization and gene expression. Besides being the structural protein making the inner nuclear membrane in polymer form, lamin A/C functions as a signalling molecule involved in gene expression as an enhancer inside the nucleus. Lamin A/C regulates various cellular pathways like autophagy and energy balance in the cytoplasm. Its expression is highly variable in differentiated tissues, higher in hard tissues like bone and muscle cells, and lower in soft tissues like the liver and brain. In muscle cells, including the heart, lamin A/C must be expressed in a balanced state. Lamin A/C mutation is linked with various diseases, such as muscular dystrophy, lipodystrophy, and cardiomyopathies. It has been observed that a good number of mutations in the LMNA gene impact cardiac activity and its function. Although several works have been published, there are still several unexplored areas left regarding the lamin A/C function and structure in the cardiovascular system and its pathological state. In this review, we focus on the structural organization, expression pattern, and function of lamin A/C, its interacting partners, and the pathophysiology associated with mutations in the lamin A/C gene, with special emphasis on cardiovascular diseases. With the recent finding on lamin A/C, we have summarized the possible therapeutic interventions to treat cardiovascular symptoms and reverse the molecular changes.
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Affiliation(s)
- Vikas Tiwari
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Guwahati 781101, Assam, India
| | - Md Jahangir Alam
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Guwahati 781101, Assam, India; Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Madhavi Bhatia
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Guwahati 781101, Assam, India
| | - Malladi Navya
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Guwahati 781101, Assam, India
| | - Sanjay K Banerjee
- Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Guwahati 781101, Assam, India.
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Danielsson BE, George Abraham B, Mäntylä E, Cabe JI, Mayer CR, Rekonen A, Ek F, Conway DE, Ihalainen TO. Nuclear lamina strain states revealed by intermolecular force biosensor. Nat Commun 2023; 14:3867. [PMID: 37391402 PMCID: PMC10313699 DOI: 10.1038/s41467-023-39563-6] [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: 04/26/2022] [Accepted: 06/19/2023] [Indexed: 07/02/2023] Open
Abstract
Nuclear lamins have been considered an important structural element of the nucleus. The nuclear lamina is thought both to shield DNA from excessive mechanical forces and to transmit mechanical forces onto the DNA. However, to date there is not yet a technical approach to directly measure mechanical forces on nuclear lamins at the protein level. To overcome this limitation, we developed a nanobody-based intermolecular tension FRET biosensor capable of measuring the mechanical strain of lamin filaments. Using this sensor, we were able to show that the nuclear lamina is subjected to significant force. These forces are dependent on nuclear volume, actomyosin contractility, functional LINC complex, chromatin condensation state, cell cycle, and EMT. Interestingly, large forces were also present on nucleoplasmic lamins, indicating that these lamins may also have an important mechanical role in the nucleus. Overall, we demonstrate that the nanobody-based approach allows construction of biosensors for complex protein structures for mechanobiology studies.
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Affiliation(s)
- Brooke E Danielsson
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Bobin George Abraham
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Elina Mäntylä
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Jolene I Cabe
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Carl R Mayer
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Anna Rekonen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Frans Ek
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Daniel E Conway
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
- The Ohio State University and Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio, USA.
| | - Teemu O Ihalainen
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.
- Tampere Institute for Advanced Study, Tampere University, Tampere, Finland.
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Wang H, Krause A, Escobar H, Müthel S, Metzler E, Spuler S. LMNA Co-Regulated Gene Expression as a Suitable Readout after Precise Gene Correction. Int J Mol Sci 2022; 23:ijms232415525. [PMID: 36555163 PMCID: PMC9778678 DOI: 10.3390/ijms232415525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/28/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022] Open
Abstract
LMNA-related muscular dystrophy is an autosomal-dominant progressive disorder caused by mutations in LMNA. LMNA missense mutations are becoming correctable with CRISPR/Cas9-derived tools. Evaluating the functional recovery of LMNA after gene editing bears challenges as there is no reported direct loss of function of lamin A/C proteins in patient-derived cells. The proteins encoded by LMNA are lamins A/C, important ubiquitous nuclear envelope proteins but absent in pluripotent stem cells. We induced lamin A/C expression in induced pluripotent stem cells (iPSCs) of two patients with LMNA-related muscular dystrophy, NM_170707.4 (LMNA): c.1366A > G, p.(Asn456Asp) and c.1494G > T, p.(Trp498Cys), using a short three-day, serum-induced differentiation protocol and analyzed expression profiles of co-regulated genes, examples being COL1A2 and S100A6. We then performed precise gene editing of LMNA c.1366A > G using the near-PAMless (PAM: protospacer-adjacent motif) cytosine base editor. We show that the mutation can be repaired to 100% efficiency in individual iPSC clones. The fast differentiation protocol provided a functional readout and demonstrated increased lamin A/C expression as well as normalized expression of co-regulated genes. Collectively, our findings demonstrate the power of CRISPR/Cas9-mediated gene correction and effective outcome measures in a disease with, so far, little perspective on therapies.
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Affiliation(s)
- Haicui Wang
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
- Correspondence: (H.W.); (S.S.); Tel.: +49-30-450-540-518 (H.W.); +49-30-450-540-501 (S.S.); Fax: +49-30-450-540-914 (H.W. & S.S.)
| | - Anne Krause
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Helena Escobar
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Stefanie Müthel
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Eric Metzler
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
| | - Simone Spuler
- Muscle Research Unit, Experimental and Clinical Research Center, a Cooperation between the Max Delbrück Center for Molecular Medicine in the Helmholtz Association and the Charité—Universitätsmedizin Berlin, 13125 Berlin, Germany
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), 13125 Berlin, Germany
- Berlin Institute of Health, Charité Universitätsmedizin Berlin, 13125 Berlin, Germany
- Correspondence: (H.W.); (S.S.); Tel.: +49-30-450-540-518 (H.W.); +49-30-450-540-501 (S.S.); Fax: +49-30-450-540-914 (H.W. & S.S.)
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Mechanisms of A-Type Lamin Targeting to Nuclear Ruptures Are Disrupted in LMNA- and BANF1-Associated Progerias. Cells 2022; 11:cells11050865. [PMID: 35269487 PMCID: PMC8909658 DOI: 10.3390/cells11050865] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/23/2022] [Accepted: 02/28/2022] [Indexed: 02/04/2023] Open
Abstract
Mutations in the genes LMNA and BANF1 can lead to accelerated aging syndromes called progeria. The protein products of these genes, A-type lamins and BAF, respectively, are nuclear envelope (NE) proteins that interact and participate in various cellular processes, including nuclear envelope rupture and repair. BAF localizes to sites of nuclear rupture and recruits NE-repair machinery, including the LEM-domain proteins, ESCRT-III complex, A-type lamins, and membranes. Here, we show that it is a mobile, nucleoplasmic population of A-type lamins that is rapidly recruited to ruptures in a BAF-dependent manner via BAF’s association with the Ig-like β fold domain of A-type lamins. These initially mobile lamins become progressively stabilized at the site of rupture. Farnesylated prelamin A and lamin B1 fail to localize to nuclear ruptures, unless that farnesylation is inhibited. Progeria-associated LMNA mutations inhibit the recruitment affected A-type lamin to nuclear ruptures, due to either permanent farnesylation or inhibition of BAF binding. A progeria-associated BAF mutant targets to nuclear ruptures but is unable to recruit A-type lamins. Together, these data reveal the mechanisms that determine how lamins respond to nuclear ruptures and how progeric mutations of LMNA and BANF1 impair recruitment of A-type lamins to nuclear ruptures.
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Most myopathic lamin variants aggregate: a functional genomics approach for assessing variants of uncertain significance. NPJ Genom Med 2021; 6:103. [PMID: 34862408 PMCID: PMC8642518 DOI: 10.1038/s41525-021-00265-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 10/21/2021] [Indexed: 02/01/2023] Open
Abstract
Hundreds of LMNA variants have been associated with several distinct disease phenotypes. However, genotype-phenotype relationships remain largely undefined and the impact for most variants remains unknown. We performed a functional analysis for 178 variants across five structural domains using two different overexpression models. We found that lamin A aggregation is a major determinant for skeletal and cardiac laminopathies. An in vitro solubility assay shows that aggregation-prone variants in the immunoglobulin-like domain correlate with domain destabilization. Finally, we demonstrate that myopathic-associated LMNA variants show aggregation patterns in induced pluripotent stem cell derived-cardiomyocytes (iPSC-CMs) in contrast to non-myopathic LMNA variants. Our data-driven approach (1) reveals that striated muscle laminopathies are predominantly protein misfolding diseases, (2) demonstrates an iPSC-CM experimental platform for characterizing laminopathic variants in human cardiomyocytes, and (3) supports a functional assay to aid in assessing pathogenicity for myopathic variants of uncertain significance.
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A rapid solubility assay of protein domain misfolding for pathogenicity assessment of rare DNA sequence variants. Genet Med 2020; 22:1642-1652. [PMID: 32475984 PMCID: PMC7529867 DOI: 10.1038/s41436-020-0842-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 02/08/2023] Open
Abstract
PURPOSE DNA sequencing technology has unmasked a vast number of uncharacterized single-nucleotide variants in disease-associated genes, and efficient methods are needed to determine pathogenicity and enable clinical care. METHODS We report an E. coli-based solubility assay for assessing the effects of variants on protein domain stability for three disease-associated proteins. RESULTS First, we examined variants in the Kv11.1 channel PAS domain (PASD) associated with inherited long QT syndrome type 2 and found that protein solubility correlated well with reported in vitro protein stabilities. A comprehensive solubility analysis of 56 Kv11.1 PASD variants revealed that disruption of membrane trafficking, the dominant loss-of-function disease mechanism, is largely determined by domain stability. We further validated this assay by using it to identify second-site suppressor PASD variants that improve domain stability and Kv11.1 protein trafficking. Finally, we applied this assay to several cancer-linked P53 tumor suppressor DNA-binding domain and myopathy-linked Lamin A/C Ig-like domain variants, which also correlated well with reported protein stabilities and functional analyses. CONCLUSION This simple solubility assay can aid in determining the likelihood of pathogenicity for sequence variants due to protein misfolding in structured domains of disease-associated genes as well as provide insights into the structural basis of disease.
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Cellular and Animal Models of Striated Muscle Laminopathies. Cells 2019; 8:cells8040291. [PMID: 30934932 PMCID: PMC6523539 DOI: 10.3390/cells8040291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/18/2019] [Accepted: 03/25/2019] [Indexed: 01/12/2023] Open
Abstract
The lamin A/C (LMNA) gene codes for nuclear intermediate filaments constitutive of the nuclear lamina. LMNA has 12 exons and alternative splicing of exon 10 results in two major isoforms—lamins A and C. Mutations found throughout the LMNA gene cause a group of diseases collectively known as laminopathies, of which the type, diversity, penetrance and severity of phenotypes can vary from one individual to the other, even between individuals carrying the same mutation. The majority of the laminopathies affect cardiac and/or skeletal muscles. The underlying molecular mechanisms contributing to such tissue-specific phenotypes caused by mutations in a ubiquitously expressed gene are not yet well elucidated. This review will explore the different phenotypes observed in established models of striated muscle laminopathies and their respective contributions to advancing our understanding of cardiac and skeletal muscle-related laminopathies. Potential future directions for developing effective treatments for patients with lamin A/C mutation-associated cardiac and/or skeletal muscle conditions will be discussed.
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8
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Peng Y, Alexov E, Basu S. Structural Perspective on Revealing and Altering Molecular Functions of Genetic Variants Linked with Diseases. Int J Mol Sci 2019; 20:ijms20030548. [PMID: 30696058 PMCID: PMC6386852 DOI: 10.3390/ijms20030548] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/25/2019] [Accepted: 01/26/2019] [Indexed: 12/25/2022] Open
Abstract
Structural information of biological macromolecules is crucial and necessary to deliver predictions about the effects of mutations-whether polymorphic or deleterious (i.e., disease causing), wherein, thermodynamic parameters, namely, folding and binding free energies potentially serve as effective biomarkers. It may be emphasized that the effect of a mutation depends on various factors, including the type of protein (globular, membrane or intrinsically disordered protein) and the structural context in which it occurs. Such information may positively aid drug-design. Furthermore, due to the intrinsic plasticity of proteins, even mutations involving radical change of the structural and physico⁻chemical properties of the amino acids (native vs. mutant) can still have minimal effects on protein thermodynamics. However, if a mutation causes significant perturbation by either folding or binding free energies, it is quite likely to be deleterious. Mitigating such effects is a promising alternative to the traditional approaches of designing inhibitors. This can be done by structure-based in silico screening of small molecules for which binding to the dysfunctional protein restores its wild type thermodynamics. In this review we emphasize the effects of mutations on two important biophysical properties, stability and binding affinity, and how structures can be used for structure-based drug design to mitigate the effects of disease-causing variants on the above biophysical properties.
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Affiliation(s)
- Yunhui Peng
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
| | - Emil Alexov
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
| | - Sankar Basu
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA.
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9
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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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10
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Pecorari I, Borin D, Sbaizero O. A Perspective on the Experimental Techniques for Studying Lamins. Cells 2017; 6:E33. [PMID: 28994747 PMCID: PMC5755493 DOI: 10.3390/cells6040033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/01/2017] [Accepted: 10/05/2017] [Indexed: 01/29/2023] Open
Abstract
Lamins are type V intermediate filaments that collectively form a meshwork underneath the inner nuclear membrane, called nuclear lamina. Furthermore, they are also present in the nucleoplasm. Lamins are experiencing a growing interest, since a wide range of diseases are induced by mutations in the gene coding for A-type lamins, globally known as laminopathies. Moreover, it has been demonstrated that lamins are involved in other pathological conditions, like cancer. The role of lamins has been studied from several perspectives, exploiting different techniques and procedures. This multidisciplinary approach has contributed to resolving the unique features of lamins and has provided a thorough insight in their role in living organisms. Yet, there are still many unanswered questions, which constantly generate research in the field. The present work is aimed to review some interesting experimental techniques performed so far to study lamins. Scientists can take advantage of this collection for their novel investigations, being aware of the already pursued and consolidated methodologies. Hopefully, advances in these research directions will provide insights to achieve better diagnostic procedures and effective therapeutic options.
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Affiliation(s)
- Ilaria Pecorari
- Department of Engineering and Architecture, University of Trieste, Via Valerio 10, 34127 Trieste, Italy.
| | - Daniele Borin
- Department of Engineering and Architecture, University of Trieste, Via Valerio 10, 34127 Trieste, Italy.
| | - Orfeo Sbaizero
- Department of Engineering and Architecture, University of Trieste, Via Valerio 10, 34127 Trieste, Italy.
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11
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Expression of progerin does not result in an increased mutation rate. Chromosome Res 2017; 25:227-239. [PMID: 28477268 PMCID: PMC5662688 DOI: 10.1007/s10577-017-9556-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 04/08/2017] [Accepted: 04/13/2017] [Indexed: 12/22/2022]
Abstract
In the premature ageing disease Hutchinson-Gilford progeria syndrome (HGPS), the underlying genetic defect in the lamin A gene leads to accumulation at the nuclear lamina of progerin—a mutant form of lamin A that cannot be correctly processed. This has been reported to result in defects in the DNA damage response and in DNA repair, leading to the hypothesis that, as in normal ageing and in other progeroid syndromes caused by mutation of genes of the DNA repair and DNA damage response pathways, increased DNA damage may be responsible for the premature ageing phenotypes in HGPS patients. However, this hypothesis is based upon the study of markers of the DNA damage response, rather than measurement of DNA damage per se or the consequences of unrepaired DNA damage—mutation. Here, using a mutation reporter cell line, we directly compared the inherent and induced mutation rates in cells expressing wild-type lamin A or progerin. We find no evidence for an elevated mutation rate in progerin-expressing cells. We conclude that the cellular defect in HGPS cells does not lie in the repair of DNA damage per se.
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12
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Kepten E, Miné-Hattab J. [Lamin A: a key protein in chromatin motion]. Med Sci (Paris) 2017; 33:126-130. [PMID: 28240200 DOI: 10.1051/medsci/20173302004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Eldad Kepten
- Institut Curie, PSL Research University, CNRS, Génétique et biologie du développement, UMR 3215, 26, rue d'Ulm, F-75005, Paris, France
| | - Judith Miné-Hattab
- Institut Curie, PSL Research University, CNRS, Dynamique du noyau, UMR 3664, 26, rue d'Ulm, F-75005, Paris, France
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13
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Moeton M, Stassen OMJA, Sluijs JA, van der Meer VWN, Kluivers LJ, van Hoorn H, Schmidt T, Reits EAJ, van Strien ME, Hol EM. GFAP isoforms control intermediate filament network dynamics, cell morphology, and focal adhesions. Cell Mol Life Sci 2016; 73:4101-20. [PMID: 27141937 PMCID: PMC5043008 DOI: 10.1007/s00018-016-2239-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 04/12/2016] [Accepted: 04/21/2016] [Indexed: 11/01/2022]
Abstract
Glial fibrillary acidic protein (GFAP) is the characteristic intermediate filament (IF) protein in astrocytes. Expression of its main isoforms, GFAPα and GFAPδ, varies in astrocytes and astrocytoma implying a potential regulatory role in astrocyte physiology and pathology. An IF-network is a dynamic structure and has been functionally linked to cell motility, proliferation, and morphology. There is a constant exchange of IF-proteins with the network. To study differences in the dynamic properties of GFAPα and GFAPδ, we performed fluorescence recovery after photobleaching experiments on astrocytoma cells with fluorescently tagged GFAPs. Here, we show for the first time that the exchange of GFP-GFAPδ was significantly slower than the exchange of GFP-GFAPα with the IF-network. Furthermore, a collapsed IF-network, induced by GFAPδ expression, led to a further decrease in fluorescence recovery of both GFP-GFAPα and GFP-GFAPδ. This altered IF-network also changed cell morphology and the focal adhesion size, but did not alter cell migration or proliferation. Our study provides further insight into the modulation of the dynamic properties and functional consequences of the IF-network composition.
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Affiliation(s)
- Martina Moeton
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Oscar M J A Stassen
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
- Soft Tissue Biomechanics & Engineering, Department of biomedical engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Jacqueline A Sluijs
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - Vincent W N van der Meer
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Liselot J Kluivers
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Hedde van Hoorn
- Physics of Life Processes, Leiden Institute of Physics, Leiden, The Netherlands
| | - Thomas Schmidt
- Physics of Life Processes, Leiden Institute of Physics, Leiden, The Netherlands
| | - Eric A J Reits
- Cell Biology and Histology, AMC Medical Center, Amsterdam, The Netherlands
| | - Miriam E van Strien
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands
| | - Elly M Hol
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands.
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands.
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14
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Bronshtein I, Kepten E, Kanter I, Berezin S, Lindner M, Redwood AB, Mai S, Gonzalo S, Foisner R, Shav-Tal Y, Garini Y. Loss of lamin A function increases chromatin dynamics in the nuclear interior. Nat Commun 2015; 6:8044. [PMID: 26299252 PMCID: PMC4560783 DOI: 10.1038/ncomms9044] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 07/11/2015] [Indexed: 01/25/2023] Open
Abstract
Chromatin is organized in a highly ordered yet dynamic manner in the cell nucleus, but the principles governing this organization remain unclear. Similarly, it is unknown whether, and how, various proteins regulate chromatin motion and as a result influence nuclear organization. Here by studying the dynamics of different genomic regions in the nucleus of live cells, we show that the genome has highly constrained dynamics. Interestingly, depletion of lamin A strikingly alters genome dynamics, inducing a dramatic transition from slow anomalous diffusion to fast and normal diffusion. In contrast, depletion of LAP2α, a protein that interacts with lamin A and chromatin, has no such effect on genome dynamics. We speculate that chromosomal inter-chain interactions formed by lamin A throughout the nucleus contribute to chromatin dynamics, and suggest that the molecular regulation of chromatin diffusion by lamin A in the nuclear interior is critical for the maintenance of genome organization.
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Affiliation(s)
- I. Bronshtein
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
- The Mina & Everard Goodman Faculty of Life Sciences and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - E. Kepten
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - I. Kanter
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - S. Berezin
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - M. Lindner
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Abena B. Redwood
- Edward A. Doisy Department of Biochemistry and Molecular Biology, School of Medicine, St Louis University, 1100 South Grand Ave. St Louis, Missouri 63104, USA
| | - S Mai
- Manitoba Institute of Cell Biology, Department of Physiology and Pathophysiology, University of Manitoba, Cancer Care Manitoba, Winnipeg, Manitoba, Canada R3E 0V9
| | - S. Gonzalo
- Edward A. Doisy Department of Biochemistry and Molecular Biology, School of Medicine, St Louis University, 1100 South Grand Ave. St Louis, Missouri 63104, USA
| | - R. Foisner
- Max F. Perutz Laboratories, Medical University Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Y. Shav-Tal
- The Mina & Everard Goodman Faculty of Life Sciences and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
| | - Y. Garini
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan 5290002, Israel
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15
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Toh KC, Ramdas NM, Shivashankar GV. Actin cytoskeleton differentially alters the dynamics of lamin A, HP1α and H2B core histone proteins to remodel chromatin condensation state in living cells. Integr Biol (Camb) 2015; 7:1309-17. [DOI: 10.1039/c5ib00027k] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cellular mechanical signals via the actin cytoskeleton regulate DNA packing by altering the dynamics of nuclear structure proteins.
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Affiliation(s)
- Kee Chua Toh
- Mechanobiology Institute
- National University of Singapore
- Singapore 117411
- Singapore
| | - Nisha M. Ramdas
- National Centre for Biological Sciences
- Tata Institute of Fundamental Research
- Bangalore 560065
- India
| | - G. V. Shivashankar
- Mechanobiology Institute
- National University of Singapore
- Singapore 117411
- Singapore
- Department of Biological Sciences
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16
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Jahn D, Schramm S, Benavente R, Alsheimer M. Dynamic properties of meiosis-specific lamin C2 and its impact on nuclear envelope integrity. Nucleus 2014. [DOI: 10.4161/nucl.11800] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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17
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Sehnalová P, Legartová S, Cmarko D, Kozubek S, Bártová E. Recruitment of HP1β to UVA-induced DNA lesions is independent of radiation-induced changes in A-type lamins. Biol Cell 2014; 106:151-65. [DOI: 10.1111/boc.201300076] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 03/03/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Petra Sehnalová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno 612 65 Czech Republic
| | - Soňa Legartová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno 612 65 Czech Republic
| | - Dušan Cmarko
- Institute of Cellular Biology and Pathology; The First Faculty of Medicine, Charles University in Prague; Prague 128 00 Czech Republic
| | - Stanislav Kozubek
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno 612 65 Czech Republic
| | - Eva Bártová
- Institute of Biophysics; Academy of Sciences of the Czech Republic; Brno 612 65 Czech Republic
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18
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Gesson K, Vidak S, Foisner R. Lamina-associated polypeptide (LAP)2α and nucleoplasmic lamins in adult stem cell regulation and disease. Semin Cell Dev Biol 2013; 29:116-24. [PMID: 24374133 PMCID: PMC4053830 DOI: 10.1016/j.semcdb.2013.12.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/10/2013] [Accepted: 12/15/2013] [Indexed: 10/25/2022]
Abstract
A-type lamins are components of the lamina network at the nuclear envelope, which mediates nuclear stiffness and anchors chromatin to the nuclear periphery. However, A-type lamins are also found in the nuclear interior. Here we review the roles of the chromatin-associated, nucleoplasmic LEM protein, lamina-associated polypeptide 2α (LAP2α) in the regulation of A-type lamins in the nuclear interior. The lamin A/C-LAP2α complex may be involved in the regulation of the retinoblastoma protein-mediated pathway and other signaling pathways balancing proliferation and differentiation, and in the stabilization of higher-order chromatin organization throughout the nucleus. Loss of LAP2α in mice leads to selective depletion of the nucleoplasmic A-type lamin pool, promotes the proliferative stem cell phenotype of tissue progenitor cells, and delays stem cell differentiation. These findings support the hypothesis that LAP2α and nucleoplasmic lamins are regulators of adult stem cell function and tissue homeostasis. Finally, we discuss potential implications of this concept for defining the molecular disease mechanisms of lamin-linked diseases such as muscular dystrophy and premature aging syndromes.
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Affiliation(s)
- Kevin Gesson
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Sandra Vidak
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Roland Foisner
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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19
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Lindenboim L, Ferrando-May E, Borner C, Stein R. Non-canonical function of Bax in stress-induced nuclear protein redistribution. Cell Mol Life Sci 2013; 70:3013-27. [PMID: 23475110 PMCID: PMC11113441 DOI: 10.1007/s00018-013-1306-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 02/13/2013] [Accepted: 02/18/2013] [Indexed: 10/27/2022]
Abstract
Bax and Bak (Bax/Bak) are essential pro-apoptotic proteins of the Bcl-2 family that trigger mitochondrial outer membrane permeabilization (MOMP) in a Bcl-2/Bcl-xL-inhibitable manner. We recently discovered a new stress-related function for Bax/Bak-regulation of nuclear protein redistribution (NPR) from the nucleus to cytoplasm. This effect was independent of Bax/Bak N-terminus exposure and not inhibited by Bcl-xL over-expression. Here, we studied the molecular mechanism governing this novel non-canonical response. Wild-type (WT) and mutant versions of Bax were re-expressed in Bax/Bak double-knockout mouse embryonic fibroblasts and their ability to promote NPR, apoptotic events, and changes in lamin A mobility was examined. Our results show that, in this system, Bax expression was sufficient to restore NPR such as in WT cells undergoing apoptosis. This activity of Bax was uncoupled from cytochrome c release from the mitochondria (indicative of MOMP) and required its membrane localization, α helices 5/6, and the Bcl-2 homology 3 (BH3) domain. Moreover, enrichment of Bax in the nuclear envelope by the so-called Klarsicht/ANC-1/Syne-1 homology domain effectively triggered NPR as in WT Bax, but without inducing MOMP or cell death. Bax-induced NPR was associated with impairment in lamin A mobility, implying a connection between these two nuclear envelope-associated events. Overall, the results indicate a new MOMP-independent, stress-induced Bax function on the nuclear envelope.
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Affiliation(s)
- Liora Lindenboim
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Ramat Aviv, Israel
| | - Elisa Ferrando-May
- Department of Biology, Bioimaging Center, University of Konstanz, 78457 Constance, Germany
| | - Christoph Borner
- Institute of Molecular Medicine and Cell Research, Albert Ludwigs University Freiburg, Stefan Meier Strasse 17, 79104 Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), Albert Ludwigs University Freiburg, Albertstrasse 19a, 79104 Freiburg, Germany
- Excellence Cluster, Centre for Biological Signaling Studies (BIOSS), Albert Ludwigs University Freiburg, Hebelstrasse 25, 79104 Freiburg, Germany
| | - Reuven Stein
- Department of Neurobiology, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Ramat Aviv, Israel
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20
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Zwerger M, Jaalouk DE, Lombardi ML, Isermann P, Mauermann M, Dialynas G, Herrmann H, Wallrath LL, Lammerding J. Myopathic lamin mutations impair nuclear stability in cells and tissue and disrupt nucleo-cytoskeletal coupling. Hum Mol Genet 2013; 22:2335-49. [PMID: 23427149 DOI: 10.1093/hmg/ddt079] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Lamins are intermediate filament proteins that assemble into a meshwork underneath the inner nuclear membrane, the nuclear lamina. Mutations in the LMNA gene, encoding lamins A and C, cause a variety of diseases collectively called laminopathies. The disease mechanism for these diverse conditions is not well understood. Since lamins A and C are fundamental determinants of nuclear structure and stability, we tested whether defects in nuclear mechanics could contribute to the disease development, especially in laminopathies affecting mechanically stressed tissue such as muscle. Using skin fibroblasts from laminopathy patients and lamin A/C-deficient mouse embryonic fibroblasts stably expressing a broad panel of laminopathic lamin A mutations, we found that several mutations associated with muscular dystrophy and dilated cardiomyopathy resulted in more deformable nuclei; in contrast, lamin mutants responsible for diseases without muscular phenotypes did not alter nuclear deformability. We confirmed our results in intact muscle tissue, demonstrating that nuclei of transgenic Drosophila melanogaster muscle expressing myopathic lamin mutations deformed more under applied strain than controls. In vivo and in vitro studies indicated that the loss of nuclear stiffness resulted from impaired assembly of mutant lamins into the nuclear lamina. Although only a subset of lamin mutations associated with muscular diseases caused increased nuclear deformability, almost all mutations tested had defects in force transmission between the nucleus and cytoskeleton. In conclusion, our results indicate that although defective nuclear stability may play a role in the development of muscle diseases, other factors, such as impaired nucleo-cytoskeletal coupling, likely contribute to the muscle phenotype.
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Affiliation(s)
- Monika Zwerger
- Department of Medicine, Brigham and Women's Hospital/Harvard Medical School, Boston, MA 02115, USA
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21
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Quantification of the Spatial Organization of the Nuclear Lamina as a Tool for Cell Classification. ISRN MOLECULAR BIOLOGY 2013; 2013:374385. [PMID: 27335676 PMCID: PMC4890873 DOI: 10.1155/2013/374385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 10/01/2013] [Indexed: 11/23/2022]
Abstract
The nuclear lamina is the structural scaffold of the nuclear envelope that plays multiple regulatory roles in chromatin organization and gene expression as well as a structural role in nuclear stability. The lamina proteins, also referred to as lamins, determine nuclear lamina organization and define the nuclear shape and the structural integrity of the cell nucleus. In addition, lamins are connected with both nuclear and cytoplasmic structures forming a dynamic cellular structure whose shape changes upon external and internal signals. When bound to the nuclear lamina, the lamins are mobile, have an impact on the nuclear envelop structure, and may induce changes in their regulatory functions. Changes in the nuclear lamina shape cause changes in cellular functions. A quantitative description of these structural changes could provide an unbiased description of changes in cellular function. In this review, we describe how changes in the nuclear lamina can be measured from three-dimensional images of lamins at the nuclear envelope, and we discuss how structural changes of the nuclear lamina can be used for cell classification.
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Abstract
Over the past two decades, the biomechanical properties of cells have emerged as key players in a broad range of cellular functions, including migration, proliferation, and differentiation. Although much of the attention has focused on the cytoskeletal networks and the cell's microenvironment, relatively little is known about the contribution of the cell nucleus. Here, we present an overview of the structural elements that determine the physical properties of the nucleus and discuss how changes in the expression of nuclear components or mutations in nuclear proteins can not only affect nuclear mechanics but also modulate cytoskeletal organization and diverse cellular functions. These findings illustrate that the nucleus is tightly integrated into the surrounding cellular structure. Consequently, changes in nuclear structure and composition are highly relevant to normal development and physiology and can contribute to many human diseases, such as muscular dystrophy, dilated cardiomyopathy, (premature) aging, and cancer.
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Affiliation(s)
- Monika Zwerger
- Department of Medicine, Brigham and Women's Hospital/Harvard Medical School, Boston, MA 02115, USA.
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23
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Lamins, laminopathies and disease mechanisms: Possible role for proteasomal degradation of key regulatory proteins. J Biosci 2011; 36:471-9. [DOI: 10.1007/s12038-011-9085-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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24
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Chaturvedi P, Parnaik VK. Lamin A rod domain mutants target heterochromatin protein 1alpha and beta for proteasomal degradation by activation of F-box protein, FBXW10. PLoS One 2010; 5:e10620. [PMID: 20498703 PMCID: PMC2869352 DOI: 10.1371/journal.pone.0010620] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2010] [Accepted: 04/20/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Lamins are major structural proteins of the nucleus and contribute to the organization of various nuclear functions. Mutations in the human lamin A gene cause a number of highly degenerative diseases, collectively termed as laminopathies. Cells expressing lamin mutations exhibit abnormal nuclear morphology and altered heterochromatin organization; however, the mechanisms responsible for these defects are not well understood. METHODOLOGY AND PRINCIPAL FINDINGS The lamin A rod domain mutants G232E, Q294P and R386K are either diffusely distributed or form large aggregates in the nucleoplasm, resulting in aberrant nuclear morphology in various cell types. We examined the effects of these lamin mutants on the distribution of heterochromatin protein 1 (HP1) isoforms. HeLa cells expressing these mutants showed a heterogeneous pattern of HP1alpha and beta depletion but without altering HP1gamma levels. Changes in HP1alpha and beta were not observed in cells expressing wild-type lamin A or mutant R482L, which assembled normally at the nuclear rim. Treatment with proteasomal inhibitors led to restoration of levels of HP1 isoforms and also resulted in stable association of lamin mutants with the nuclear periphery, rim localization of the inner nuclear membrane lamin-binding protein emerin and partial improvement of nuclear morphology. A comparison of the stability of HP1 isoforms indicated that HP1alpha and beta displayed increased turnover and higher basal levels of ubiquitination than HP1gamma. Transcript analysis of components of the ubiquitination pathway showed that a specific F-box protein, FBXW10 was induced several-fold in cells expressing lamin mutants. Importantly, ectopic expression of FBXW10 in HeLa cells led to depletion of HP1alpha and beta without alteration of HP1gamma levels. CONCLUSIONS Mislocalized lamins can induce ubiquitin-mediated proteasomal degradation of certain HP1 isoforms by activation of FBXW10, a member of the F-box family of proteins that is involved in E3 ubiquitin ligase activity.
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Affiliation(s)
| | - Veena K. Parnaik
- Centre for Cellular and Molecular Biology (CSIR), Hyderabad, India
- * E-mail:
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25
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Jahn D, Schramm S, Benavente R, Alsheimer M. Dynamic properties of meiosis-specific lamin C2 and its impact on nuclear envelope integrity. Nucleus 2010; 1:273-83. [PMID: 21327075 DOI: 10.4161/nucl.1.3.11800] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 03/12/2010] [Accepted: 03/15/2010] [Indexed: 11/19/2022] Open
Abstract
A hallmark of meiosis is the precise pairing and the stable physical connection (synapsis) of the homologous chromosomes. These processes are essential prerequisite for their proper segregation. Pairing of the homologs during meiotic prophase I critically depends on characteristic movements of chromosomes. These movements, in turn, require attachment of meiotic telomeres to the nuclear envelope and their subsequent dynamic repositioning. Dynamic repositioning of meiotic telomeres goes along with profound structural reorganization of the nuclear envelope. The short A-type lamin C2 is thought to play a critical role in this process due to its specific expression during meiotic prophase I and the unique localization surrounding telomere attachments. Consistent with this notion, here we provide compelling evidence that meiosis-specific lamin C2 features a significantly increased mobility compared to somatic lamins as revealed by photobleaching techniques. We show that this property can be clearly ascribed to the lack of the N-terminal head and the significantly shorter α-helical coil domain. Moreover, expression of lamin C2 in somatic cells induces nuclear deformations and alters the distribution of the endogenous nuclear envelope proteins lamin B1, LAP2, SUN1 and SUN2. Together, our data define lamin C2 as a "natural lamin deletion mutant" that confers unique properties to the nuclear envelope which would be essential for dynamic telomere repositioning during meiotic prophase I.
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Affiliation(s)
- Daniel Jahn
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Germany
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26
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Cowan J, Li D, Gonzalez-Quintana J, Morales A, Hershberger RE. Morphological analysis of 13 LMNA variants identified in a cohort of 324 unrelated patients with idiopathic or familial dilated cardiomyopathy. ACTA ACUST UNITED AC 2009; 3:6-14. [PMID: 20160190 DOI: 10.1161/circgenetics.109.905422] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Mutations in the LMNA gene, encoding lamins A/C, represent a significant cause of dilated cardiomyopathy. We recently identified 18 protein-altering LMNA variants in a cohort of 324 unrelated patients with dilated cardiomyopathy. However, at least one family member with dilated cardiomyopathy in each of 6 pedigrees lacked the LMNA mutation (nonsegregation), whereas small sizes of 5 additional families precluded definitive determinations of segregation, raising questions regarding contributions by those variants to disease. METHODS AND RESULTS We have consequently expressed, in COS7 cells, GFP-prelamin A (GFPLaA) fusion constructs incorporating the 6 variants in pedigrees with nonsegregation (R101P, A318T, R388H, R399C, S437Hfsx1, and R654X), the 4 variants in pedigrees with unknown segregation (R89L, R166P [in 2 families], I210S, R471H), and 3 additional missense variants (R190Q, E203K, and L215P) that segregated with disease. Confocal immunofluorescence microscopy was used to characterize GFP-lamin A localization and nuclear morphology. Abnormal phenotypes were observed for 10 of 13 (77%) variants (R89L, R101P, R166P, R190Q, E203K, I210S, L215P, R388H, S437Hfsx1, and R654X), including 4 of 6 showing nonsegregation and 3 of 4 with uncertain segregation. All 7 variants affecting coil 1B and the lamin A-only mutation, R654X, exhibited membrane-bound GFP-lamin A aggregates and nuclear shape abnormalities. Unexpectedly, R388H largely restricted GFP-lamin A to the cytoplasm. Equally unexpected were unique streaked aggregates with S437Hfsx1 and giant aggregates with both S437Hfsx1 and R654X. CONCLUSIONS This work expands the recognized spectrum of lamin A localization abnormalities in dilated cardiomyopathy. It also provides evidence supporting pathogenicity of 10 of 13 tested LMNA variants, including some with uncertain or nonsegregation.
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Affiliation(s)
- Jason Cowan
- Cardiovascular Division, Department of Medicine, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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27
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Abstract
In eukaryotic cells, the nucleus contains the genome and is the site of transcriptional regulation. The nucleus is the largest and stiffest organelle and is exposed to mechanical forces transmitted through the cytoskeleton from outside the cell and from force generation within the cell. Here, we discuss the effect of intra- and extracellular forces on nuclear shape and structure and how these force-induced changes could be implicated in nuclear mechanotransduction, ie, force-induced changes in cell signaling and gene transcription. We review mechanical studies of the nucleus and nuclear structural proteins, such as lamins. Dramatic changes in nuclear shape, organization, and stiffness are seen in cells where lamin proteins are mutated or absent, as in genetically engineered mice, RNA interference studies, or human disease. We examine the different mechanical pathways from the force-responsive cytoskeleton to the nucleus. We also highlight studies that link changes in nuclear shape with cell function during developmental, physiological, and pathological modifications. Together, these studies suggest that the nucleus itself may play an important role in the response of the cell to force.
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Affiliation(s)
- Kris Noel Dahl
- Department of Biomedical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA.
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28
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Specific contribution of lamin A and lamin C in the development of laminopathies. Exp Cell Res 2008; 314:2362-75. [PMID: 18538321 DOI: 10.1016/j.yexcr.2008.04.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 04/28/2008] [Accepted: 04/28/2008] [Indexed: 01/12/2023]
Abstract
Mutations in the lamin A/C gene are involved in multiple human disorders for which the pathophysiological mechanisms are partially understood. Conflicting results prevail regarding the organization of lamin A and C mutants within the nuclear envelope (NE) and on the interactions of each lamin to its counterpart. We over-expressed various lamin A and C mutants both independently and together in COS7 cells. When expressed alone, lamin A with cardiac/muscular disorder mutations forms abnormal aggregates inside the NE and not inside the nucleoplasm. Conversely, the equivalent lamin C organizes as intranucleoplasmic aggregates that never connect to the NE as opposed to wild type lamin C. Interestingly, the lamin C molecules present within these aggregates exhibit an abnormal increased mobility. When co-expressed, the complex formed by lamin A/C aggregates in the NE. Lamin A and C mutants for lipodystrophy behave similarly to the wild type. These findings reveal that lamins A and C may be differentially affected depending on the mutation. This results in multiple possible physiological consequences which likely contribute in the phenotypic variability of laminopathies. The inability of lamin C mutants to join the nuclear rim in the absence of lamin A is a potential pathophysiological mechanism for laminopathies.
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29
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Tang CW, Maya-Mendoza A, Martin C, Zeng K, Chen S, Feret D, Wilson SA, Jackson DA. The integrity of a lamin-B1-dependent nucleoskeleton is a fundamental determinant of RNA synthesis in human cells. J Cell Sci 2008; 121:1014-24. [PMID: 18334554 DOI: 10.1242/jcs.020982] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spatial organisation of nuclear compartments is an important regulator of chromatin function, yet the molecular principles that maintain nuclear architecture remain ill-defined. We have used RNA interference to deplete key structural nuclear proteins, the nuclear lamins. In HeLa cells, we show that reduced expression of lamin B1, but not lamin A/C, severely inhibits RNA synthesis--first by RNA polymerase II and later by RNA polymerase I. Declining levels of transcription correlate with different morphological changes in major nuclear compartments, nucleoli and nuclear speckles. Ultimately, nuclear changes linked to the loss of synthetic activity result in expansion of the inter-chromatin domain and corresponding changes in the structure and spatial organisation of chromosome territories, which relocate towards the nuclear periphery. These results show that a lamin B1-containing nucleoskeleton is required to maintain RNA synthesis and that ongoing synthesis is a fundamental determinant of global nuclear architecture in mammalian cells.
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Affiliation(s)
- Chi W Tang
- Faculty of Life Sciences, University of Manchester, MIB, 131 Princess Street, Manchester, M1 7DN, UK
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30
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Parnaik VK. Role of Nuclear Lamins in Nuclear Organization, Cellular Signaling, and Inherited Diseases. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:157-206. [DOI: 10.1016/s1937-6448(07)66004-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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31
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Yamanaka H, Yakabe Y, Saito K, Sekijima M, Shirai T. Quantitative proteomic analysis of rat liver for carcinogenicity prediction in a 28-day repeated dose study. Proteomics 2007; 7:781-95. [PMID: 17295351 DOI: 10.1002/pmic.200600235] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The potential of quantitative proteomic analysis to predict carcinogenicity of chemical compounds was investigated. Using 2D-DIGE, we analyzed the effects of 63 chemical compounds on protein expression in the rat liver after 28 daily doses. Types of carcinogens were categorized depending on the species and organ specificity. The carcinogen characteristic proteins for each classification were identified by Welch's t value. For evaluation of the predictive concordance we used support vector machines. The rat hepatic carcinogen-specific classification gave higher concordance than the other classification. The generalization performance was measured by leave-one-out cross-validation. For genotoxic and non-genotoxic compounds, a concordance of 79.3 and 76.5%, respectively, was obtained by the top 30 ranked proteins with Welch's t value. Furthermore, we found that the increase of the expression level of the stress response proteins as the common feature of poorly predicted chemical compounds in the leave-20%-out cross-validation. Quantitative proteomics could be promising technique for developing biomarker panels that can be used for carcinogenicity prediction. The list of proteins identified in this study and the zoomed gel images of the top ranked proteins in statistic analysis are provided in Supplementary Data.
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Affiliation(s)
- Hidenori Yamanaka
- Chemicals Assessment Center, Chemicals Evaluation and Research Institute, Saitama, Japan.
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32
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Parnaik VK, Manju K. Laminopathies: multiple disorders arising from defects in nuclear architecture. J Biosci 2006; 31:405-21. [PMID: 17006023 DOI: 10.1007/bf02704113] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lamins are the major structural proteins of the nucleus in an animal cell. In addition to being essential for nuclear integrity and assembly, lamins are involved in the organization of nuclear processes such as DNA replication, transcription and repair. Mutations in the human lamin A gene lead to highly debilitating genetic disorders that primarily affect muscle, adipose, bone or neuronal tissues and also cause premature ageing syndromes. Mutant lamins alter nuclear integrity and hinder signalling pathways involved in muscle differentiation and adipocyte differentiation, suggesting tissue-specific roles for lamins. Furthermore, cells expressing mutant lamins are impaired in their response to DNA damaging agents. Recent reports indicate that certain lamin mutations act in a dominant negative manner to cause nuclear defects and cellular toxicity, and suggest a possible role for aberrant lamins in normal ageing processes.
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Affiliation(s)
- Veena K Parnaik
- Centre for Cellular and Molecular Biology, Hyderabad, India.
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33
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Hübner S, Eam JE, Wagstaff KM, Jans DA. Quantitative analysis of localization and nuclear aggregate formation induced by GFP-lamin A mutant proteins in living HeLa cells. J Cell Biochem 2006; 98:810-26. [PMID: 16440304 DOI: 10.1002/jcb.20791] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although A-type lamins are ubiquitously expressed, their role in the tissue-specificity of human laminopathies remains enigmatic. In this study, we generate a series of transfection constructs encoding missense lamin A mutant proteins fused to green fluorescent protein and investigate their subnuclear localization using quantitative live cell imaging. The mutant constructs used included the laminopathy-inducing lamin A rod domain mutants N195K, E358K, M371K, R386K, the tail domain mutants G465D, R482L, and R527P, and the Hutchinson-Gilford progeria syndrome-causing deletion mutant, progerin (LaA delta50). All mutant derivatives induced nuclear aggregates, except for progerin, which caused a more lobulated phenotype of the nucleus. Quantitative analysis revealed that the frequency of nuclear aggregate formation was significantly higher (two to four times) for the mutants compared to the wild type, although the level of lamin fusion proteins within nuclear aggregates was not. The distribution of endogenous A-type lamins was altered by overexpression of the lamin A mutants, coexpression experiments revealing that aberrant localization of the N195K and R386K mutants had no effect on the subnuclear distribution of histones H2A or H2B, or on nuclear accumulation of H2A overexpressed as a DsRed2 fusion protein. The GFP-lamin fusion protein-expressing constructs will have important applications in the future, enabling live cell imaging of nuclear processes involving lamins and how this may relate to the pathogenesis of laminopathies.
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Affiliation(s)
- S Hübner
- Nuclear Signaling Laboratory, Department of Biochemistry and Molecular Biology, PO Box 13D, Monash University, Clayton, Victoria 3800, Australia.
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Manju K, Muralikrishna B, Parnaik VK. Expression of disease-causing lamin A mutants impairs the formation of DNA repair foci. J Cell Sci 2006; 119:2704-14. [PMID: 16772334 DOI: 10.1242/jcs.03009] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A-type lamins are components of the nuclear lamina. Mutations in the gene encoding lamin A are associated with a range of highly degenerative diseases termed laminopathies. To evaluate sensitivity to DNA damage, GFP-tagged lamin A cDNAs with disease-causing mutations were expressed in HeLa cells. The inner nuclear membrane protein emerin was mislocalised upon expression of the muscular dystrophy mutants G232E, Q294P or R386K, which aberrantly assembled into nuclear aggregates, or upon expression of mutants causing progeria syndromes in vivo (lamin A del50, R471C, R527C and L530P). The ability of cells expressing these mutants to form DNA repair foci comprising phosphorylated H2AX in response to mild doses of cisplatin or UV irradiation was markedly diminished, unlike the nearly normal response of cells expressing wild-type GFP-lamin A or disease-causing H222P and R482L mutants. Interestingly, mutants that impaired the formation of DNA repair foci mislocalised ATR (for ;ataxia telangiectasia-mutated and Rad3-related') kinase, which is a key sensor in the response to DNA damage. Our results suggest that a subset of lamin A mutants might hinder the response of components of the DNA repair machinery to DNA damage by altering interactions with chromatin.
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Affiliation(s)
- Kaliyaperumal Manju
- Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
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Ostlund C, Sullivan T, Stewart CL, Worman HJ. Dependence of diffusional mobility of integral inner nuclear membrane proteins on A-type lamins. Biochemistry 2006; 45:1374-82. [PMID: 16445279 PMCID: PMC2527696 DOI: 10.1021/bi052156n] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Integral proteins of the nuclear envelope inner membrane have been proposed to reach their sites by diffusion after their co-translational insertion in the rough endoplasmic reticulum. They are then retained in the inner nuclear membrane by binding to nuclear structures. One such structure is the nuclear lamina, an intermediate filament meshwork composed of A-type and B-type lamin proteins. Emerin, MAN1, and LBR are three integral inner nuclear membrane proteins. We expressed these proteins fused to green fluorescent protein in embryonic fibroblasts from wild-type mice and Lmna -/- mice, which lack A-type lamins. We then studied the diffusional mobilities of emerin, MAN1, and LBR using fluorescence recovery after photobleaching. We show that emerin and MAN1, but not LBR, are more mobile in the inner nuclear membrane of cells from Lmna -/- mice than in cells from wild-type mice. In cells from Lmna -/- mice expressing exogenous lamin A, the protein mobilities were similar to those in cells from wild-type mice. This supports a model where emerin and MAN1 are at least partly retained in the inner nuclear membrane by binding to A-type lamins, while LBR depends on other binding partners for its retention.
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Affiliation(s)
- Cecilia Ostlund
- Department of Medicine, College of Physicians and Surgeons, Columbia University, Room 10-509, 630 West 168th Street, New York, New York 10032, USA
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Maraldi NM, Lattanzi G, Capanni C, Columbaro M, Mattioli E, Sabatelli P, Squarzoni S, Manzoli FA. Laminopathies: A chromatin affair. ACTA ACUST UNITED AC 2006; 46:33-49. [PMID: 16857244 DOI: 10.1016/j.advenzreg.2006.01.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Schütz W, Benavente R, Alsheimer M. Dynamic properties of germ line-specific lamin B3: the role of the shortened rod domain. Eur J Cell Biol 2005; 84:649-62. [PMID: 16106909 DOI: 10.1016/j.ejcb.2005.03.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The mammalian lamin B2 gene codes for two proteins, the somatic lamin B2 and the germ line-specific lamin B3. Lamin B3 lacks the N-terminus and a part of the alpha-helical rod domain present in lamin B2. These domains are substituted by 84 amino acids unique for lamin B3. When ectopically expressed in somatic cells, lamin B3 causes severe deformation of nuclei which adopt a hook-like configuration. Accordingly, it was proposed that lamin B3 provides the germ line cells with a more flexible nuclear periphery that facilitates spermatogenesis-specific nuclear reorganization events. Here we investigated which protein domains of lamin B3 are responsible for nuclear deformation in transfected cells, and how stable is the nuclear periphery of these cells. Expression of wild-type and mutant lamins evidenced that nuclear deformations are due to the shortened rod domain of lamin B3. Cell fractionation experiments revealed that lamin B3 can be solubilized more easily than lamin B2. Fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP) analyses of transfected cells showed that lamin B3 has an increased mobility compared to B2. Our results lead to the conclusion that lamin B3 reduces the stability of the nuclear periphery. They are also consistent with the notion that lamin B3 is relevant to specific properties of the nuclear envelope during spermiogenesis.
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Affiliation(s)
- Wolfgang Schütz
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Germany
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Abstract
The latest development of imaging technology and fluorescent proteins has enabled us to visualize the dynamics of chromatin proteins in living cells. Particularly, photobleaching techniques like fluorescence recovery after photobleaching (FRAP) revealed the mobility of many nuclear proteins including histones. Although most nucleosomal histones are maintained over cell generations to maintain epigenetic marks on their tails, some exhibit dynamic exchange. In general, histone H3-H4 tetramers stably bind to DNA once assembled during DNA replication; in contrast, the H2A-H2B dimers exchange slowly in euchromatin and are evicted during transcription. Recent data further indicate that different histone variants have different localization and kinetics. The replacement H3 variant, H3.3, is incorporated into transcriptionally active chromatin independently of DNA replication, and the centromeric variant, CENP-A, appears to assemble into nucleosomes in centromeres during G2 phase by replacing canonical H3. Different behaviors of H2A variants are also demonstrated. Importantly, the mobility of histones, and other nuclear proteins, is altered in response to changes in cellular physiology and various stimuli. Whereas we know little about how these dynamics are regulated, distinct complexes that mediate assembly and exchange of specific variants have been isolated, thus future analyses will reveal the molecular mechanisms underlying the phenomena in living cells.
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Affiliation(s)
- Hiroshi Kimura
- Nuclear Function and Dynamics Unit, HMRO, School of Medicine, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.
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Worman HJ, Courvalin JC. Nuclear envelope, nuclear lamina, and inherited disease. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 246:231-79. [PMID: 16164970 DOI: 10.1016/s0074-7696(05)46006-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The nuclear envelope is composed of the nuclear membranes, nuclear lamina, and nuclear pore complexes. In recent years, mutations in nuclear-envelope proteins have been shown to cause a surprisingly wide array of inherited diseases. While the mutant proteins are generally expressed in most or all differentiated somatic cells, many mutations cause fairly tissue-specific disorders. Perhaps the most dramatic case is that of mutations in A-type lamins, intermediate filament proteins associated with the inner nuclear membrane. Different mutations in the same lamin proteins have been shown to cause striated muscle diseases, partial lipodystrophy syndromes, a peripheral neuropathy, and disorders with features of severe premature aging. In this review, we summarize fundamental aspects of nuclear envelope structure and function, the inherited diseases caused by mutations in lamins and other nuclear envelope proteins, and possible pathogenic mechanisms.
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Affiliation(s)
- Howard J Worman
- Department of Medicine and Department of Anatomy and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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