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Schamberger B, Ehrig S, Dechat T, Spitzer S, Bidan CM, Fratzl P, Dunlop JWC, Roschger A. Twisted-plywood-like tissue formation in vitro. Does curvature do the twist? PNAS Nexus 2024; 3:pgae121. [PMID: 38590971 PMCID: PMC10999733 DOI: 10.1093/pnasnexus/pgae121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 02/23/2024] [Indexed: 04/10/2024]
Abstract
Little is known about the contribution of 3D surface geometry to the development of multilayered tissues containing fibrous extracellular matrix components, such as those found in bone. In this study, we elucidate the role of curvature in the formation of chiral, twisted-plywood-like structures. Tissues consisting of murine preosteoblast cells (MC3T3-E1) were grown on 3D scaffolds with constant-mean curvature and negative Gaussian curvature for up to 32 days. Using 3D fluorescence microscopy, the influence of surface curvature on actin stress-fiber alignment and chirality was investigated. To gain mechanistic insights, we did experiments with MC3T3-E1 cells deficient in nuclear A-type lamins or treated with drugs targeting cytoskeleton proteins. We find that wild-type cells form a thick tissue with fibers predominantly aligned along directions of negative curvature, but exhibiting a twist in orientation with respect to older tissues. Fiber orientation is conserved below the tissue surface, thus creating a twisted-plywood-like material. We further show that this alignment pattern strongly depends on the structural components of the cells (A-type lamins, actin, and myosin), showing a role of mechanosensing on tissue organization. Our data indicate the importance of substrate curvature in the formation of 3D tissues and provide insights into the emergence of chirality.
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Affiliation(s)
- Barbara Schamberger
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
| | - Sebastian Ehrig
- Laboratory of Systems Biology of Gene Regulatory Elements, Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Hannoversche Str. 28, 10115 Berlin, Germany
| | - Thomas Dechat
- Ludwig Boltzmann Institute of Osteology of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria
| | - Silvia Spitzer
- Ludwig Boltzmann Institute of Osteology of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria
| | - Cécile M Bidan
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Peter Fratzl
- Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - John W C Dunlop
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
| | - Andreas Roschger
- Department of the Chemistry and Physics of Materials, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria
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Werzowa J, Behanova M, Handisurya A, Heger F, Indra A, Holzer B, Dechat T, Spitzer S, Lederer S, Kraus DA, Zwerina J, Fritsch-Stork RDE. Response to Immunization against SARS-CoV-2 and Risk of Omicron Infection in Dialysis Patients: A Prospective Cohort Study. J Clin Med 2023; 12:4983. [PMID: 37568385 PMCID: PMC10419800 DOI: 10.3390/jcm12154983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 07/19/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
It is not well established to what extent previous immunizations offer protection against infections with the SARS-CoV-2 Omicron variant in dialysis patients. We aimed to define the relevant humoral response in dialysis patients using a SARS-CoV-2 IgG chemiluminescence microparticle immunoassay (CMIA) compared to the activity of neutralizing antibodies assessed by a virus neutralization test. Next, we aimed to determine differences in humoral and cellular response levels over time among patients infected or not infected by the Omicron variant of SARS-CoV-2. Immunological parameters of cellular and humoral response to SARS-CoV-2 were analyzed at baseline and after 3 (T3), 6 (T6) and 14 months (T14). In this monocentric cohort study, we followed 110 dialysis patients (mean age 68.4 ± 13.7 years, 60.9% male) for a median of 545 days. We determined an anti-SARS-CoV-2 IgG level of 56.7 BAU/mL as an ideal cut-off value with a J-index of 90.7. Patients infected during the Omicron era had significantly lower (p < 0.001) mean antibody levels at T0 (3.5 vs. 111.2 BAU/mL), T3 (269.8 vs. 699.8 BAU/mL) and T6 (260.2 vs. 513.9 BAU/mL) than patients without Omicron infection. Patients who developed higher antibody levels at the time of the basic immunizations were less likely to become infected with SARS-CoV-2 during the Omicron era. There is a need to adjust the cut-off values for anti-SARS-CoV-2 IgG levels in dialysis patients.
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Affiliation(s)
- Johannes Werzowa
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
- 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria; (A.H.); (S.L.)
| | - Martina Behanova
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
| | - Ammon Handisurya
- 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria; (A.H.); (S.L.)
| | - Florian Heger
- Austrian Agency for Health and Food Safety (AGES), 1090 Vienna, Austria; (F.H.); (A.I.)
| | - Alexander Indra
- Austrian Agency for Health and Food Safety (AGES), 1090 Vienna, Austria; (F.H.); (A.I.)
| | - Barbara Holzer
- Institute for Veterinary Disease Control, Austrian Agency for Health and Food Safety (AGES), 2340 Moedling, Austria;
| | - Thomas Dechat
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
| | - Silvia Spitzer
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
| | - Sandra Lederer
- 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria; (A.H.); (S.L.)
| | - Daniel A. Kraus
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
- 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria; (A.H.); (S.L.)
| | - Jochen Zwerina
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1140 Vienna, Austria; (J.W.); (T.D.); (S.S.); (D.A.K.); (J.Z.)
- 1st Medical Department, Hanusch Hospital, 1140 Vienna, Austria; (A.H.); (S.L.)
| | - Ruth D. E. Fritsch-Stork
- Medical Center Mariahilf of OEGK, 1060 Vienna, Austria;
- Medical Faculty, Sigmund Freud Private University, 1020 Vienna, Austria
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Kronschläger M, Ruiß M, Dechat T, Findl O. Single high-dose peroral caffeine intake inhibits ultraviolet radiation-induced apoptosis in human lens epithelial cells in vitro. Acta Ophthalmol 2021; 99:e587-e593. [PMID: 33124749 DOI: 10.1111/aos.14641] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 09/03/2020] [Accepted: 09/06/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE The aim of the present study was to determine whether caffeine concentrations in human lens epithelial cells (LECs) achieved from acute peroral caffeine intake inhibit ultraviolet radiation-induced apoptosis in vitro. METHODS Patients were planned for cataract surgery of both eyes with a caffeine abstinence of 2 weeks in total, starting 1 week before surgery of the first eye. The second eye was scheduled 1 week after the first eye. At the day of the second eye surgery, patients were given coffee containing 180 mg caffeine shortly before surgery. Lens capsules including LEC, harvested after capsulorhexis, were transferred to a cell culture dish and immediately exposed to close to threshold ultraviolet radiation (UVR). At 24 hr after UVR exposure, apoptotic LECs were analysed by TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining. RESULTS TUNEL-positive cells were detected in UVR-exposed lens capsules both after caffeine intake and in controls. The mean difference in TUNEL-positive cells between caffeine intake and contralateral controls (no caffeine) resulted in a 95% CI 15.3 ± 10.4% (degrees of freedom: 16). CONCLUSION Peroral caffeine consumption significantly decreased UVR-induced apoptosis in LEC supporting epidemiological findings that caffeine delays the onset of cataract.
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Affiliation(s)
- Martin Kronschläger
- Vienna Institute for Research in Ocular Surgery Hanusch Hospital Vienna Austria
| | - Manuel Ruiß
- Vienna Institute for Research in Ocular Surgery Hanusch Hospital Vienna Austria
| | - Thomas Dechat
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling 1st Medical Department Hanusch Hospital Vienna Austria
| | - Oliver Findl
- Vienna Institute for Research in Ocular Surgery Hanusch Hospital Vienna Austria
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Naetar N, Georgiou K, Knapp C, Bronshtein I, Zier E, Fichtinger P, Dechat T, Garini Y, Foisner R. LAP2alpha maintains a mobile and low assembly state of A-type lamins in the nuclear interior. eLife 2021; 10:63476. [PMID: 33605210 PMCID: PMC7939549 DOI: 10.7554/elife.63476] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 02/18/2021] [Indexed: 01/08/2023] Open
Abstract
Lamins form stable filaments at the nuclear periphery in metazoans. Unlike B-type lamins, lamins A and C localize also in the nuclear interior, where they interact with lamin-associated polypeptide 2 alpha (LAP2α). Using antibody labeling, we previously observed a depletion of nucleoplasmic A-type lamins in mouse cells lacking LAP2α. Here, we show that loss of LAP2α actually causes formation of larger, biochemically stable lamin A/C structures in the nuclear interior that are inaccessible to lamin A/C antibodies. While nucleoplasmic lamin A forms from newly expressed pre-lamin A during processing and from soluble mitotic lamins in a LAP2α-independent manner, binding of LAP2α to lamin A/C during interphase inhibits formation of higher order structures, keeping nucleoplasmic lamin A/C in a mobile state independent of lamin A/C S22 phosphorylation. We propose that LAP2α is essential to maintain a mobile lamin A/C pool in the nuclear interior, which is required for proper nuclear functions.
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Affiliation(s)
- Nana Naetar
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Konstantina Georgiou
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Christian Knapp
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Irena Bronshtein
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel
| | - Elisabeth Zier
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Petra Fichtinger
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Thomas Dechat
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
| | - Yuval Garini
- Physics Department and Nanotechnology Institute, Bar Ilan University, Ramat Gan, Israel
| | - Roland Foisner
- Max Perutz Labs, Center for Medical Biochemistry, Medical University of Vienna, Vienna Biocenter Campus (VBC), Vienna, Austria
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5
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Vidak S, Georgiou K, Fichtinger P, Naetar N, Dechat T, Foisner R. Nucleoplasmic lamins define growth-regulating functions of lamina-associated polypeptide 2α in progeria cells. J Cell Sci 2018; 131:jcs208462. [PMID: 29361532 PMCID: PMC5826045 DOI: 10.1242/jcs.208462] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 12/18/2017] [Indexed: 01/01/2023] Open
Abstract
A-type lamins are components of the peripheral nuclear lamina but also localize in the nuclear interior in a complex with lamina-associated polypeptide (LAP) 2α. Loss of LAP2α and nucleoplasmic lamins in wild-type cells increases cell proliferation, but in cells expressing progerin (a mutant lamin A that causes Hutchinson-Gilford progeria syndrome), low LAP2α levels result in proliferation defects. Here, the aim was to understand the molecular mechanism governing how relative levels of LAP2α, progerin and nucleoplasmic lamins affect cell proliferation. Cells from progeria patients and inducible progerin-expressing cells expressing low levels of progerin proliferate faster than wild-type or lamin A-expressing control cells, and ectopic expression of LAP2α impairs proliferation. In contrast, cells expressing high levels of progerin and lacking lamins in the nuclear interior proliferate more slowly, and ectopic LAP2α expression enhances proliferation. However, simultaneous expression of LAP2α and wild-type lamin A or an assembly-deficient lamin A mutant restored the nucleoplasmic lamin A pool in these cells and abolished the growth-promoting effect of LAP2α. Our data show that LAP2α promotes or inhibits proliferation of progeria cells depending on the level of A-type lamins in the nuclear interior.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Sandra Vidak
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Konstantina Georgiou
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Petra Fichtinger
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Nana Naetar
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Thomas Dechat
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Roland Foisner
- Max F. Perutz Laboratories (MFPL), Center of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
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6
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Allmaier G, Blaas D, Bliem C, Dechat T, Fedosyuk S, Gösler I, Kowalski H, Weiss VU. Monolithic anion-exchange chromatography yields rhinovirus of high purity. J Virol Methods 2017; 251:15-21. [PMID: 28966037 DOI: 10.1016/j.jviromet.2017.09.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 09/27/2017] [Accepted: 09/27/2017] [Indexed: 11/26/2022]
Abstract
For vaccine development, 3D-structure determination, direct fluorescent labelling, and numerous other studies, homogeneous virus preparations of high purity are essential. Working with human rhinoviruses (RVs), members of the picornavirus family and the main cause of generally mild respiratory infections, we noticed that our routine preparations appeared highly pure on analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), exclusively showing the four viral capsid proteins (VPs). However, the preparations turned out to contain substantial amounts of contaminating material when analyzed by orthogonal analytical methods including capillary zone electrophoresis, nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA), and negative stain transmission electron microscopy (TEM). Because these latter analyses are not routine to many laboratories, the above contaminations might remain unnoticed and skew experimental results. By using human rhinovirus serotype A2 (RV-A2) as example we report monolithic anion-exchange chromatography (AEX) as a last polishing step in the purification and demonstrate that it yields infective, highly pure, virus (RV-A2 in the respective fractions was confirmed by peptide mass fingerprinting) devoid of foreign material as judged by the above criteria.
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Affiliation(s)
- Günter Allmaier
- Institute of Chemical Technologies and Analytics, TU Wien (Vienna University of Technology), Vienna, Austria
| | - Dieter Blaas
- Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Christina Bliem
- Institute of Chemical Technologies and Analytics, TU Wien (Vienna University of Technology), Vienna, Austria
| | - Thomas Dechat
- Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Sofiya Fedosyuk
- Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Irene Gösler
- Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Heinrich Kowalski
- Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Victor U Weiss
- Institute of Chemical Technologies and Analytics, TU Wien (Vienna University of Technology), Vienna, Austria.
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7
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Gesson K, Rescheneder P, Skoruppa MP, von Haeseler A, Dechat T, Foisner R. A-type lamins bind both hetero- and euchromatin, the latter being regulated by lamina-associated polypeptide 2 alpha. Genome Res 2016; 26:462-73. [PMID: 26798136 PMCID: PMC4817770 DOI: 10.1101/gr.196220.115] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 01/19/2016] [Indexed: 11/24/2022]
Abstract
Lamins are components of the peripheral nuclear lamina and interact with heterochromatic genomic regions, termed lamina-associated domains (LADs). In contrast to lamin B1 being primarily present at the nuclear periphery, lamin A/C also localizes throughout the nucleus, where it associates with the chromatin-binding protein lamina-associated polypeptide (LAP) 2 alpha. Here, we show that lamin A/C also interacts with euchromatin, as determined by chromatin immunoprecipitation of euchromatin- and heterochromatin-enriched samples. By way of contrast, lamin B1 was only found associated with heterochromatin. Euchromatic regions occupied by lamin A/C overlap with those bound by LAP2alpha, and lack of LAP2alpha in LAP2alpha-deficient cells shifts binding of lamin A/C toward more heterochromatic regions. These alterations in lamin A/C-chromatin interactions correlate with changes in epigenetic histone marks in euchromatin but do not significantly affect gene expression. Loss of lamin A/C in heterochromatic regions in LAP2alpha-deficient cells, however, correlated with increased gene expression. Our data show a novel role of nucleoplasmic lamin A/C and LAP2alpha in regulating euchromatin.
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Affiliation(s)
- Kevin Gesson
- Department of Medical Biochemistry, Medical University of Vienna, A-1030 Vienna, Austria
| | - Philipp Rescheneder
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories (MFPL), Medical University of Vienna and University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria
| | - Michael P Skoruppa
- Department of Medical Biochemistry, Medical University of Vienna, A-1030 Vienna, Austria
| | - Arndt von Haeseler
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories (MFPL), Medical University of Vienna and University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria; Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, A-1030 Vienna, Austria
| | - Thomas Dechat
- Department of Medical Biochemistry, Medical University of Vienna, A-1030 Vienna, Austria
| | - Roland Foisner
- Department of Medical Biochemistry, Medical University of Vienna, A-1030 Vienna, Austria
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8
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Vidak S, Kubben N, Dechat T, Foisner R. Proliferation of progeria cells is enhanced by lamina-associated polypeptide 2α (LAP2α) through expression of extracellular matrix proteins. Genes Dev 2016; 29:2022-36. [PMID: 26443848 PMCID: PMC4604344 DOI: 10.1101/gad.263939.115] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A single heterozygous mutation of LMNA generates the lamin A/C variant progerin and causes Hutchinson-Gilford progeria syndrome (HGPS). Vidak et al. show that this mutation leads to loss of LAP2α and nucleoplasmic lamins A/C, impaired proliferation, and down-regulation of extracellular matrix components. Ectopic expression of LAP2α in cells expressing progerin restores proliferation and extracellular matrix expression but not the levels of nucleoplasmic lamins A/C. Lamina-associated polypeptide 2α (LAP2α) localizes throughout the nucleoplasm and interacts with the fraction of lamins A/C that is not associated with the peripheral nuclear lamina. The LAP2α–lamin A/C complex negatively affects cell proliferation. Lamins A/C are encoded by LMNA, a single heterozygous mutation of which causes Hutchinson-Gilford progeria syndrome (HGPS). This mutation generates the lamin A variant progerin, which we show here leads to loss of LAP2α and nucleoplasmic lamins A/C, impaired proliferation, and down-regulation of extracellular matrix components. Surprisingly, contrary to wild-type cells, ectopic expression of LAP2α in cells expressing progerin restores proliferation and extracellular matrix expression but not the levels of nucleoplasmic lamins A/C. We conclude that, in addition to its cell cycle-inhibiting function with lamins A/C, LAP2α can also regulate extracellular matrix components independently of lamins A/C, which may help explain the proliferation-promoting function of LAP2α in cells expressing progerin.
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Affiliation(s)
- Sandra Vidak
- Max F. Perutz Laboratories (MFPL), Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria
| | - Nard Kubben
- National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Thomas Dechat
- Max F. Perutz Laboratories (MFPL), Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria
| | - Roland Foisner
- Max F. Perutz Laboratories (MFPL), Department of Medical Biochemistry, Medical University of Vienna, Vienna Biocenter (VBC), A-1030 Vienna, Austria
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9
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Pilat U, Dechat T, Bertrand AT, Woisetschläger N, Gotic I, Spilka R, Biadasiewicz K, Bonne G, Foisner R. The muscle dystrophy-causing ΔK32 lamin A/C mutant does not impair the functions of the nucleoplasmic lamin-A/C-LAP2α complex in mice. J Cell Sci 2013; 126:1753-62. [PMID: 23444379 DOI: 10.1242/jcs.115246] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A-type lamins are components of the nuclear lamina, a filamentous network of the nuclear envelope in metazoans that supports nuclear architecture. In addition, lamin A/C can also be found in the interior of the nucleus. This nucleoplasmic lamin pool is soluble in physiological buffer, depends on the presence of the lamin-binding protein, lamina-associated polypeptide 2α (LAP2α) and regulates cell cycle progression in tissue progenitor cells. ΔK32 mutations in A-type lamins cause severe congenital muscle disease in humans and a muscle maturation defect in Lmna(ΔK32/ΔK32) knock-in mice. Mutant ΔK32 lamin A/C protein levels were reduced and all mutant lamin A/C was soluble and mislocalized to the nucleoplasm. To test the role of LAP2α in nucleoplasmic ΔK32 lamin A/C regulation and functions, we deleted LAP2α in Lmna(ΔK32/ΔK32) knock-in mice. In double mutant mice the Lmna(ΔK32/ΔK32)-linked muscle defect was unaffected. LAP2α interacted with mutant lamin A/C, but unlike wild-type lamin A/C, the intranuclear localization of ΔK32 lamin A/C was not affected by loss of LAP2α. In contrast, loss of LAP2α in Lmna(ΔK32/ΔK32) mice impaired the regulation of tissue progenitor cells as in lamin A/C wild-type animals. These data indicate that a LAP2α-independent assembly defect of ΔK32 lamin A/C is the predominant cause of the mouse pathology, whereas the LAP2α-linked functions of nucleoplasmic lamin A/C in the regulation of tissue progenitor cells are not affected in Lmna(ΔK32/ΔK32) mice.
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Affiliation(s)
- Ursula Pilat
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
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Abstract
Nuclear lamins were originally described as the main constituents of the nuclear lamina, a filamentous meshwork closely associated with the inner nuclear membrane. However, within recent years, it has become increasingly evident that a fraction of lamins also resides throughout the nuclear interior. As intermediate-filament-type proteins, lamins have been suggested to fulfill mainly structural functions such as providing shape and mechanical stability to the nucleus. But recent findings show that both peripheral and nucleoplasmic lamins also have important roles in essential cellular processes such as transcription, DNA replication, cell cycle progression, and chromatin organization. Furthermore, more than 300 mutations in the gene encoding A-type lamins have been associated with several human diseases now generally termed laminopathies and comprising muscular dystrophies, lipodystrophies, cardiomyopathies, and premature aging diseases. This review focuses on the lamina-independent pool of lamins in the nuclear interior, which surprisingly has not been studied in much detail so far. We discuss the properties and regulation of nucleoplasmic lamins during the cell cycle, their interaction partners, and their potential involvement in cellular processes and the development of laminopathies.
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Affiliation(s)
- T Dechat
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Vienna 1030, Austria
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11
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Abstract
The nuclear lamins are type V intermediate filament proteins that are critically important for the structural properties of the nucleus. In addition, they are involved in the regulation of numerous nuclear processes, including DNA replication, transcription and chromatin organization. The developmentally regulated expression of lamins suggests that they are involved in cellular differentiation. Their assembly dynamic properties throughout the cell cycle, particularly in mitosis, are influenced by posttranslational modifications. Lamins may regulate nuclear functions by direct interactions with chromatin and determining the spatial organization of chromosomes within the nuclear space. They may also regulate chromatin functions by interacting with factors that epigenetically modify the chromatin or directly regulate replication or transcription.
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Affiliation(s)
- Thomas Dechat
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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12
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Eriksson JE, Dechat T, Grin B, Helfand B, Mendez M, Pallari HM, Goldman RD. Introducing intermediate filaments: from discovery to disease. J Clin Invest 2009; 119:1763-71. [PMID: 19587451 DOI: 10.1172/jci38339] [Citation(s) in RCA: 301] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
It took more than 100 years before it was established that the proteins that form intermediate filaments (IFs) comprise a unified protein family, the members of which are ubiquitous in virtually all differentiated cells and present both in the cytoplasm and in the nucleus. However, during the past 2 decades, knowledge regarding the functions of these structures has been expanding rapidly. Many disease-related roles of IFs have been revealed. In some cases, the molecular mechanisms underlying these diseases reflect disturbances in the functions traditionally assigned to IFs, i.e., maintenance of structural and mechanical integrity of cells and tissues. However, many disease conditions seem to link to the nonmechanical functions of IFs, many of which have been defined only in the past few years.
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Affiliation(s)
- John E Eriksson
- Department of Biology, Abo Akademi University, Turku, Finland.
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Affiliation(s)
- Thomas Dechat
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
| | - Stephen A. Adam
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
| | - Robert D. Goldman
- Northwestern University Medical School, Department of Cell and Molecular Biology, Chicago, Illinois 60611, USA
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Dechat T, Pfleghaar K, Sengupta K, Shimi T, Shumaker DK, Solimando L, Goldman RD. Nuclear lamins: major factors in the structural organization and function of the nucleus and chromatin. Genes Dev 2008; 22:832-53. [PMID: 18381888 PMCID: PMC2732390 DOI: 10.1101/gad.1652708] [Citation(s) in RCA: 712] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Over the past few years it has become evident that the intermediate filament proteins, the types A and B nuclear lamins, not only provide a structural framework for the nucleus, but are also essential for many aspects of normal nuclear function. Insights into lamin-related functions have been derived from studies of the remarkably large number of disease-causing mutations in the human lamin A gene. This review provides an up-to-date overview of the functions of nuclear lamins, emphasizing their roles in epigenetics, chromatin organization, DNA replication, transcription, and DNA repair. In addition, we discuss recent evidence supporting the importance of lamins in viral infections.
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Affiliation(s)
- Thomas Dechat
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Katrin Pfleghaar
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Kaushik Sengupta
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Takeshi Shimi
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Dale K. Shumaker
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Liliana Solimando
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Dechat T, Shimi T, Adam SA, Rusinol AE, Andres DA, Spielmann HP, Sinensky MS, Goldman RD. Alterations in mitosis and cell cycle progression caused by a mutant lamin A known to accelerate human aging. Proc Natl Acad Sci U S A 2007; 104:4955-60. [PMID: 17360326 PMCID: PMC1829246 DOI: 10.1073/pnas.0700854104] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mutations in the gene encoding nuclear lamin A (LA) cause the premature aging disease Hutchinson-Gilford Progeria Syndrome. The most common of these mutations results in the expression of a mutant LA, with a 50-aa deletion within its C terminus. In this study, we demonstrate that this deletion leads to a stable farnesylation and carboxymethylation of the mutant LA (LADelta50/progerin). These modifications cause an abnormal association of LADelta50/progerin with membranes during mitosis, which delays the onset and progression of cytokinesis. Furthermore, we demonstrate that the targeting of nuclear envelope/lamina components into daughter cell nuclei in early G(1) is impaired in cells expressing LADelta50/progerin. The mutant LA also appears to be responsible for defects in the retinoblastoma protein-mediated transition into S-phase, most likely by inhibiting the hyperphosphorylation of retinoblastoma protein by cyclin D1/cdk4. These results provide insights into the mechanisms responsible for premature aging and also shed light on the role of lamins in the normal process of human aging.
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Affiliation(s)
- Thomas Dechat
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Takeshi Shimi
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Stephen A. Adam
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Antonio E. Rusinol
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Box 70581,Johnson City, TN 37614; and
| | | | - H. Peter Spielmann
- Departments of Molecular and Cellular Biochemistry and
- Chemistry and
- Kentucky Center for Structural Biology, University of Kentucky, 741 South Limestone, Lexington, KY 40536
| | - Michael S. Sinensky
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Box 70581,Johnson City, TN 37614; and
| | - Robert D. Goldman
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
- To whom correspondence should be addressed. E-mail:
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Naetar N, Hutter S, Dorner D, Dechat T, Korbei B, Gotzmann J, Beug H, Foisner R. LAP2alpha-binding protein LINT-25 is a novel chromatin-associated protein involved in cell cycle exit. J Cell Sci 2007; 120:737-47. [PMID: 17284516 DOI: 10.1242/jcs.03390] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Lamina-associated polypeptide 2alpha (LAP2alpha) is a nuclear protein dynamically associating with chromatin during the cell cycle. In addition, LAP2alpha interacts with A-type lamins and retinoblastoma protein and regulates cell cycle progression via the E2F-Rb pathway. Using yeast two-hybrid analysis and three independent in vitro binding assays we identified a new LAP2alpha interaction partner of hitherto unknown functions, which we termed LINT-25. LINT-25 protein levels were upregulated during G1 phase in proliferating cells and upon cell cycle exit in quiescence, senescence and differentiation. Upon cell cycle exit LINT-25 accumulated in heterochromatin foci, and LAP2alpha protein levels were downregulated by proteasomal degradation. Although LAP2alpha was not required for the upregulation and reorganization of LINT-25 during cell cycle exit, transient expression of LINT-25 in proliferating cells caused loss of LAP2alpha and subsequent cell death. Our data show a role of LINT-25 and LAP2alpha during cell cycle exit, in which LINT-25 acts upstream of LAP2alpha.
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Affiliation(s)
- Nana Naetar
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr-Gasse 9, Vienna Biocenter, Dr. Bohr-Gasse 7, A-1030 Vienna, Austria
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Snyers L, Vlcek S, Dechat T, Skegro D, Korbei B, Gajewski A, Mayans O, Schöfer C, Foisner R. Lamina-associated polypeptide 2-alpha forms homo-trimers via its C terminus, and oligomerization is unaffected by a disease-causing mutation. J Biol Chem 2007; 282:6308-15. [PMID: 17213199 DOI: 10.1074/jbc.m605782200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The nucleoplasmic protein, Lamina-associated polypeptide (LAP) 2alpha, is one of six alternatively spliced products of the LAP2gene, which share a common N-terminal region. In contrast to the other isoforms, which also share most of their C termini, LAP2alpha has a large unique C-terminal region that contains binding sites for chromatin, A-type lamins, and retinoblastoma protein. By immunoprecipitation analyses of LAP2alpha complexes from cells expressing differently tagged LAP2alpha proteins and fragments, we demonstrate that LAP2alpha forms higher order structures containing multiple LAP2alpha molecules in vivo and that complex formation is mediated by the C terminus. Solid phase binding assays using recombinant and in vitro translated LAP2alpha fragments showed direct interactions of LAP2alpha C termini. Cross-linking of LAP2alpha complexes and multiangle light scattering of purified LAP2alpha revealed the existence of stable homo-trimers in vivo and in vitro. Finally, we show that, in contrast to the LAP2alpha-lamin A interaction, its self-association is not affected by a disease-linked single point mutation in the LAP2alpha C terminus.
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Affiliation(s)
- Luc Snyers
- Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstrasse 17, A-1090 Vienna, Austria
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Shumaker DK, Dechat T, Kohlmaier A, Adam SA, Bozovsky MR, Erdos MR, Eriksson M, Goldman AE, Khuon S, Collins FS, Jenuwein T, Goldman RD. Mutant nuclear lamin A leads to progressive alterations of epigenetic control in premature aging. Proc Natl Acad Sci U S A 2006; 103:8703-8. [PMID: 16738054 PMCID: PMC1472659 DOI: 10.1073/pnas.0602569103] [Citation(s) in RCA: 543] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The premature aging disease Hutchinson-Gilford Progeria Syndrome (HGPS) is caused by a mutant lamin A (LADelta50). Nuclei in cells expressing LADelta50 are abnormally shaped and display a loss of heterochromatin. To determine the mechanisms responsible for the loss of heterochromatin, epigenetic marks regulating either facultative or constitutive heterochromatin were examined. In cells from a female HGPS patient, histone H3 trimethylated on lysine 27 (H3K27me3), a mark for facultative heterochromatin, is lost on the inactive X chromosome (Xi). The methyltransferase responsible for this mark, EZH2, is also down-regulated. These alterations are detectable before the changes in nuclear shape that are considered to be the pathological hallmarks of HGPS cells. The results also show a down-regulation of the pericentric constitutive heterochromatin mark, histone H3 trimethylated on lysine 9, and an altered association of this mark with heterochromatin protein 1alpha (Hp1alpha) and the CREST antigen. This loss of constitutive heterochromatin is accompanied by an up-regulation of pericentric satellite III repeat transcripts. In contrast to these decreases in histone H3 methylation states, there is an increase in the trimethylation of histone H4K20, an epigenetic mark for constitutive heterochromatin. Expression of LADelta50 in normal cells induces changes in histone methylation patterns similar to those seen in HGPS cells. The epigenetic changes described most likely represent molecular mechanisms responsible for the rapid progression of premature aging in HGPS patients.
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Affiliation(s)
- Dale K. Shumaker
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Thomas Dechat
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Alexander Kohlmaier
- Research Institute of Molecular Pathology, Dr. Bohrgasse 7, A-1030 Vienna, Austria
| | - Stephen A. Adam
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Matthew R. Bozovsky
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Michael R. Erdos
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892; and
| | - Maria Eriksson
- Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Halsovagen 7, Hiss E, Plan 6, 141 57 Huddinge, Sweden
| | - Anne E. Goldman
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Satya Khuon
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
| | - Francis S. Collins
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892; and
- To whom correspondence may be addressed. E-mail:
or
| | - Thomas Jenuwein
- Research Institute of Molecular Pathology, Dr. Bohrgasse 7, A-1030 Vienna, Austria
| | - Robert D. Goldman
- *Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611
- To whom correspondence may be addressed. E-mail:
or
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Abstract
Nuclear lamins are type V intermediate filament proteins. They are the major building blocks of the peripheral nuclear lamina, a complex meshwork of proteins underlying the inner nuclear membrane. In addition to providing nuclear shape and mechanical stability, they are required for chromatin organization, transcription regulation, DNA replication, nuclear assembly and nuclear positioning. Over the past few years, interest in the lamins has increased because of the identification of at least 12 distinct human diseases associated with mutations in the LMNA gene, which encodes A-type lamins. These diseases, collectively termed laminopathies, affect muscle, adipose, bone, nerve and skin cells and range from muscular dystrophies to accelerated aging.
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Affiliation(s)
- Anna Mattout
- Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Dechat T, Gajewski A, Korbei B, Gerlich D, Daigle N, Haraguchi T, Furukawa K, Ellenberg J, Foisner R. LAP2α and BAF transiently localize to telomeres and specific regions on chromatin during nuclear assembly. J Cell Sci 2004; 117:6117-28. [PMID: 15546916 DOI: 10.1242/jcs.01529] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Lamina-associated polypeptide (LAP) 2α is a LEM (lamina-associated polypeptide emerin MAN1) family protein associated with nucleoplasmic A-type lamins and chromatin. Using live cell imaging and fluorescence microscopy we demonstrate that LAP2α was mostly cytoplasmic in metaphase and associated with telomeres in anaphase. Telomeric LAP2α clusters grew in size, formed `core' structures on chromatin adjacent to the spindle in telophase, and translocated to the nucleoplasm in G1 phase. A subfraction of lamin C and emerin followed LAP2α to the core region early on, whereas LAP2β, lamin B receptor and lamin B initially bound to more peripheral regions of chromatin, before they spread to core structures with different kinetics. Furthermore, the DNA-crosslinking protein barrier-to-autointegration factor (BAF) bound to LAP2α in vitro and in mitotic extracts, and subfractions of BAF relocalized to core structures with LAP2α. We propose that LAP2α and a subfraction of BAF form defined complexes in chromatin core regions and may be involved in chromatin reorganization during early stages of nuclear assembly.
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Affiliation(s)
- Thomas Dechat
- Max F. Perutz Laboratories, University Departments at the Vienna Biocenter, Department of Medical Biochemistry, Medical University of Vienna, 1030 Vienna, Austria
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Mostafaie N, Rossmanith W, Hombauer H, Dechat T, Raffelsberger T, Bauer K, Worofka B, Kittl E, Hofmann J, Hejtman M, Kirchmeyr W, Schreiber W, Weissgram S, Jungwirth S, Fischer P, Bittner R, Huber K. Mitochondrial genotype and risk for Alzheimer's disease: cross-sectional data from the Vienna-Transdanube-Aging "VITA" study. J Neural Transm (Vienna) 2004; 111:1155-65. [PMID: 15338331 DOI: 10.1007/s00702-004-0161-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2004] [Accepted: 04/17/2004] [Indexed: 11/26/2022]
Abstract
The Vienna Transdanube Aging (VITA) study searches for early markers of Alzheimer's disease (AD) by examining the mental status in a community-based cohort of 606, 75-years old volunteers that are then related to various clinical and genetic analyses. To determine whether mutations in mtDNA are involved in expression of AD, the mtDNA of 79 "control" participants is screened for alterations by sequencing of "hot-spot-regions". This study on mtDNA mutations has eliminated the influence of aging on the occurrence of mtDNA alterations by sequencing samples from persons at the age of exactly 75 years. Thus, our cohort reveals a snap-shot of mitochondrial sequences of elderly persons. So far, a high percentage (56%) of persons with known or unknown mutations in the fragments analyzed were found. These data will be compared in due time to a cohort of participants with proven late-onset AD.
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Affiliation(s)
- N Mostafaie
- L. Boltzmann Institute of Aging Research, Ludwig Boltzmann Society, Donauspital, Austria
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Markiewicz E, Dechat T, Foisner R, Quinlan RA, Hutchison CJ. Lamin A/C binding protein LAP2alpha is required for nuclear anchorage of retinoblastoma protein. Mol Biol Cell 2002; 13:4401-13. [PMID: 12475961 PMCID: PMC138642 DOI: 10.1091/mbc.e02-07-0450] [Citation(s) in RCA: 200] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The phosphorylation-dependent anchorage of retinoblastoma protein Rb in the nucleus is essential for its function. We show that its pocket C domain is both necessary and sufficient for nuclear anchorage by transiently expressing green fluorescent protein (GFP) chimeras of Rb fragments in tissue culture cells and by extracting the cells with hypotonic solutions. Solid phase binding assays using glutathione S-transferase-fusion of Rb pockets A, B, and C revealed a direct association of lamin C exclusively to pocket C. Lamina-associated polypeptide (LAP) 2alpha, a binding partner of lamins A/C, bound strongly to pocket C and weakly to pocket B. When LAP2alpha was immunoprecipitated from soluble nuclear fractions, lamins A/C and hypophosphorylated Rb were coprecipitated efficiently. Similarly, immunoprecipitation of expressed GFP-Rb fragments by using anti-GFP antibodies coprecipitated LAP2alpha, provided that pocket C was present in the GFP chimeras. On redistribution of endogenous lamin A/C and LAP2alpha into nuclear aggregates by overexpressing dominant negative lamin mutants in tissue culture cells, Rb was also sequestered into these aggregates. In primary skin fibroblasts, LAP2alpha is expressed in a growth-dependent manner. Anchorage of hypophosphorylated Rb in the nucleus was weakened significantly in the absence of LAP2alpha. Together, these data suggest that hypophosphorylated Rb is anchored in the nucleus by the interaction of pocket C with LAP2alpha-lamin A/C complexes.
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Affiliation(s)
- Ewa Markiewicz
- Department of Biological Sciences, The University of Durham, Durham DH1 3LE, United Kingdom
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Abstract
The peripheral nuclear lamina is located near the nuclear inner membrane and consists of lamin filaments and integral membrane proteins, including the lamin B receptor and various isoforms of lamina-associated polypeptides (LAP) 1 and 2. Several nuclear membrane proteins also interact with chromatin proteins BAF and Hp1. Lamins in the nuclear interior associate with at least one soluble (non-membrane-bound) LAP2 isoform named LAP2alpha. The internal lamins, together with Tpr-based filaments that connect to nuclear pore complexes, are proposed to be major structural elements of the internal nuclear matrix. We describe the structural links between the peripheral lamina and the internal nuclear matrix that are thought to be mediated by LAP2 family members, filament protein Tpr and nucleoporin Nup153. These findings are discussed in relation to human diseases that arise from mutations in nuclear lamina proteins.
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Affiliation(s)
- S Vlcek
- Department of Biochemistry and Molecular Cell Biology, Vienna Biocenter, University of Vienna, Austria
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Nussbaumer P, Dechat T. Ready Access to 6-Alkyl, 6-Phenyl, 5,6-Dialkyl, and 5-Alkyl-6-phenyl Substituted 1,2,3,4-Tetrahydroisoquinolines. Monatshefte fuer Chemie/Chemical Monthly 2001. [DOI: 10.1007/s007060170045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
The nucleoskeletal protein lamina-associated polypeptide 2(α) (LAP2*) contains a large, unique C terminus and differs significantly from its alternatively spliced, mostly membrane-integrated isoforms, such as LAP2beta. Unlike lamin B-binding LAP2beta, LAP2alpha was found by confocal immunofluorescence microscopy to colocalize preferentially with A-type lamins in the newly formed nuclei assembled after mitosis. While only a subfraction of lamins A and C (lamin A/C) was associated with the predominantly nuclear LAP2alpha in telophase, the majority of lamin A/C colocalized with LAP2alpha in G(1)-phase nuclei. Furthermore, selective disruption of A-type lamin structures by overexpression of lamin mutants in HeLa cells caused a redistribution of LAP2alpha. Coimmunoprecipitation experiments revealed that a fraction of lamin A/C formed a stable, SDS-resistant complex with LAP2alpha in interphase cells and in postmetaphase cell extracts. Blot overlay binding studies revealed a direct binding of LAP2alpha to exclusively A-type lamins and located the interaction domains to the C-terminal 78 amino acids of LAP2alpha and to residues 319–566 in lamin A/C, which include the C terminus of the rod and the entire tail common to lamin A/C. These findings suggest that LAP2alpha and A-type lamins cooperate in the organization of internal nuclear structures.
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Affiliation(s)
- T Dechat
- Department of Biochemistry and Molecular Cell Biology, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
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Dechat T, Vlcek S, Foisner R. Review: lamina-associated polypeptide 2 isoforms and related proteins in cell cycle-dependent nuclear structure dynamics. J Struct Biol 2000; 129:335-45. [PMID: 10806084 DOI: 10.1006/jsbi.2000.4212] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lamina-associated polypeptide (LAP) 2 family comprises up to six alternatively spliced proteins in mammalian cells and three isoforms in Xenopus. LAP2beta is a type II integral protein of the inner nuclear membrane, which binds to lamin B and the chromosomal protein BAF, and may link the nuclear membrane to the underlying lamina and provide docking sites for chromatin. LAP2alpha shares only the N-terminus with the other isoforms and contains a unique C-terminus. It is a nonmembrane protein associated with the nucleoskeleton and may help to organize higher order chromatin structure by interacting with A-lamins and chromosomes. Recent studies using mutant proteins have just begun to unravel functions of LAP2 isoforms during postmitotic nuclear reassembly. LAP2alpha associates with chromosomes via an alpha-specific domain at early stages of assembly, possibly providing a structural framework for chromosome reorganization. The subsequent interaction of both LAP2alpha and LAP2beta with the chromosomal BAF may stabilize chromatin structure and target membranes to the chromosomes. At later stages LAP2 may regulate the assembly of lamins. LAP2 isoforms have been found to share a homologous approximately 40 amino acid long region, the LEM domain, with nuclear membrane proteins MAN1 and emerin, which has been implicated in Emery-Dreifuss muscular dystrophy.
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Affiliation(s)
- T Dechat
- Department of Biochemistry and Molecular Cell Biology, Biocenter, Vienna, A-1030, Austria
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Meissner M, Dechat T, Gerner C, Grimm R, Foisner R, Sauermann G. Differential nuclear localization and nuclear matrix association of the splicing factors PSF and PTB. J Cell Biochem 2000; 76:559-66. [PMID: 10653975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
A monoclonal antibody raised against nuclear matrix proteins detected a protein of basic pI in human nuclear matrix protein samples of various cellular origin. The ubiquitously occurring (common) nuclear matrix protein was identified as splicing factor PSF (PTB associated splicing factor). The interaction between the splicing factors PSF and PTB/hnRNP I was confirmed by co-immunoprecipitation from nuclear salt extracts. However, the nuclear localization of PSF and PTB and their distribution in subnuclear fractions differed markedly. Isolated nuclear matrices contained the bulk of PSF, but only minor amounts of PTB. In confocal microscopy both proteins appeared in speckles, the majority of which did not co-localize. Removing a large fraction of the soluble PTB structures by salt extraction revealed some colocalization of the more stable PTB fraction with PSF. These PTB/PSF complexes as well as the observed PSF-PTB interaction may reflect the previously reported presence of PTB and PSF in spliceosomal complexes during RNA processing. The present data, however, point to different cellular distribution and nuclear matrix association of the majority of PSF and PTB.
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Affiliation(s)
- M Meissner
- Institute of Tumor Biology-Cancer Research, University of Vienna, A-1090 Vienna, Austria
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Vlcek S, Just H, Dechat T, Foisner R. Functional diversity of LAP2alpha and LAP2beta in postmitotic chromosome association is caused by an alpha-specific nuclear targeting domain. EMBO J 1999; 18:6370-84. [PMID: 10562549 PMCID: PMC1171700 DOI: 10.1093/emboj/18.22.6370] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Lamina-associated polypeptide 2alpha (LAP2alpha) is a non-membrane-bound isoform of the LAP2 family implicated in nuclear structure organization. We show that during postmitotic nuclear assembly LAP2alpha associates with chromosomes prior to accumulation of the membrane-bound isoform LAP2beta, although both proteins contain the same putative chromatin interaction domains located in their common N-terminal regions. By transient and stable expression of various N- and C-terminal LAP2alpha deletion mutants in HeLa cells, we identified an approximately 350-amino-acid-long region in the C-terminal alpha-specific domain of the protein that is required for retention of LAP2alpha in interphase nuclei and for association with mitotic chromosomes, while the N-terminal domain seemed to be dispensable for these interactions. In vitro chromosome binding studies using recombinant LAP2alpha mutants revealed that this LAP2alpha-specific 'nuclear targeting domain' was essential and sufficient for association with chromosomes. These data suggested a functional diversity of chromosome binding properties of LAP2 isoforms.
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Affiliation(s)
- S Vlcek
- Department of Biochemistry and Molecular Cell Biology, Biocenter, University of Vienna, Dr Bohrgasse 9, A-1030 Vienna, Austria
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30
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Dechat T, Gotzmann J, Stockinger A, Harris CA, Talle MA, Siekierka JJ, Foisner R. Detergent-salt resistance of LAP2alpha in interphase nuclei and phosphorylation-dependent association with chromosomes early in nuclear assembly implies functions in nuclear structure dynamics. EMBO J 1998; 17:4887-902. [PMID: 9707448 PMCID: PMC1170818 DOI: 10.1093/emboj/17.16.4887] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Lamina-associated polypeptide (LAP) 2 of the inner nuclear membrane (now LAP2beta) and LAP2alpha are related proteins produced by alternative splicing, and contain a common 187 amino acid N-terminal domain. We show here that, unlike LAP2beta, LAP2alpha behaved like a nuclear non-membrane protein in subcellular fractionation studies and was localized throughout the nuclear interior in interphase cells. It co-fractionated with LAP2beta in nuclear lamina/matrix-enriched fractions upon extraction of nuclei with detergent, salt and nucleases. During metaphase LAP2alpha dissociated from chromosomes and became concentrated around the spindle poles. Furthermore, LAP2alpha was mitotically phosphorylated, and phosphorylation correlated with increased LAP2alpha solubility upon extraction of cells in physiological buffers. LAP2alpha relocated to distinct sites around chromosomes at early stages of nuclear reassembly and intermediarily co-localized with peripheral lamin B and intranuclear lamin A structures at telophase. During in vitro nuclear assembly LAP2alpha was dephosphorylated and assembled into insoluble chromatin-associated structures, and recombinant LAP2alpha was found to interact with chromosomes in vitro. Some LAP2alpha may also associate with membranes prior to chromatin attachment. Altogether the data suggest a role of LAP2alpha in post-mitotic nuclear assembly and in the dynamic structural organization of the nucleus.
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Affiliation(s)
- T Dechat
- nstitute of Biochemistry and Molecular Cell Biology, Biocenter and Institute of Tumor Biology-Cancer Research, University of Vienna, A-1030 Vienna, Austria
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Nussbaumer P, Baumann K, Dechat T, Harasek M. Highly selective TFAA-cleavage of tertiary 2,4-dimethoxybenzylamines and its use in the synthesis of secondary amines. Tetrahedron 1991. [DOI: 10.1016/s0040-4020(01)86465-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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