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Sato Y, Takenoshita M, Ueoka M, Ueda J, Yamagata K, Kimura H. Visualizing histone H4K20me1 in knock-in mice expressing the mCherry-tagged modification-specific intracellular antibody. Histochem Cell Biol 2024; 162:41-52. [PMID: 38762823 PMCID: PMC11227479 DOI: 10.1007/s00418-024-02296-8] [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] [Accepted: 05/03/2024] [Indexed: 05/20/2024]
Abstract
During development and differentiation, histone modifications dynamically change locally and globally, associated with transcriptional regulation, DNA replication and repair, and chromosome condensation. The level of histone H4 Lys20 monomethylation (H4K20me1) increases during the G2 to M phases of the cell cycle and is enriched in facultative heterochromatin, such as inactive X chromosomes in cycling cells. To track the dynamic changes of H4K20me1 in living cells, we have developed a genetically encoded modification-specific intracellular antibody (mintbody) probe that specifically binds to the modification. Here, we report the generation of knock-in mice in which the coding sequence of the mCherry-tagged version of the H4K20me1-mintbody is inserted into the Rosa26 locus. The knock-in mice, which ubiquitously expressed the H4K20me1-mintbody, developed normally and were fertile, indicating that the expression of the probe does not disturb the cell growth, development, or differentiation. Various tissues isolated from the knock-in mice exhibited nuclear fluorescence without the need for fixation. The H4K20me1-mintbody was enriched in inactive X chromosomes in developing embryos and in XY bodies during spermatogenesis. The knock-in mice will be useful for the histochemical analysis of H4K20me1 in any cell types.
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Affiliation(s)
- Yuko Sato
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan
| | - Maoko Takenoshita
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan
| | - Miku Ueoka
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan
| | - Jun Ueda
- Center for Genetic Analysis of Biological Responses, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, 565-0871, Japan
- Department of Advanced Medical Science, Asahikawa Medical University, Asahikawa, Hokkaido, 078-8510, Japan
| | - Kazuo Yamagata
- Center for Genetic Analysis of Biological Responses, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, 565-0871, Japan
- Faculty of Biology-Oriented Science and Technology, Kindai University, Kinokawa, Wakayama, 649-6493, Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan.
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8501, Japan.
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2
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Müller B, Serafin F, Laucke LL, Rheinhard W, Wimmer T, Stieger K. Characterization of Double-Strand Break Repair Protein Ku80 Location Within the Murine Retina. Invest Ophthalmol Vis Sci 2022; 63:22. [PMID: 35737378 PMCID: PMC9233284 DOI: 10.1167/iovs.63.6.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To characterize the spatial distribution of the DNA-double strand break-repair protein Ku80 in the murine retina. Even though robust data exist on the complexity of DNA repair mechanisms in dividing cells in vitro, almost nothing is known about it in post-mitotic neurons or photoreceptors (PRs). This knowledge is an important prerequisite for in vivo therapeutic approaches by genome editing in retina and PRs. Recently, it was shown that mouse rod PRs are incapable of repairing double-strand breaks induced by radiation. Material and Methods Retinae from wild-type, rd10, and RPGR-KI mouse lines were obtained and stained with antibodies against Ku80, and cellular markers CtBP2, beta-Dystropglycan, Lamin B, and peanut agglutinin. Organotypic explant cultures were generated and maintained for up to 10 days. Laser microdissection was performed to obtain photoreceptor nuclei, and Ku80 expression was compared to whole retina by real-time PCR (RT-PCR). Results Strong Ku80 immunoreactivity was observed in rod but not cone photoreceptor terminals localized in the outer plexiform layer of the retina in all three mouse lines. During retinal explant culture, we observed that Ku80-positive globules translocate into the heterochromatin region of nuclei in the outer nuclear layer (ONL). By quantitative PCR, we showed upregulation of relative Ku80 expression in the ONL during wild-type retinal explant culture. Discussion The unexpected localization of Ku80 to murine rod terminals indicates another tissue-specific modification to the canonical DNA repair mechanisms and warrants further investigation.
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Affiliation(s)
- Brigitte Müller
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Franziska Serafin
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Leonie Luise Laucke
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Wilhelm Rheinhard
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Tobias Wimmer
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Knut Stieger
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
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3
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Leidescher S, Ribisel J, Ullrich S, Feodorova Y, Hildebrand E, Galitsyna A, Bultmann S, Link S, Thanisch K, Mulholland C, Dekker J, Leonhardt H, Mirny L, Solovei I. Spatial organization of transcribed eukaryotic genes. Nat Cell Biol 2022; 24:327-339. [PMID: 35177821 DOI: 10.1038/s41556-022-00847-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 01/10/2022] [Indexed: 12/19/2022]
Abstract
Despite the well-established role of nuclear organization in the regulation of gene expression, little is known about the reverse: how transcription shapes the spatial organization of the genome. Owing to the small sizes of most previously studied genes and the limited resolution of microscopy, the structure and spatial arrangement of a single transcribed gene are still poorly understood. Here we study several long highly expressed genes and demonstrate that they form open-ended transcription loops with polymerases moving along the loops and carrying nascent RNAs. Transcription loops can span across micrometres, resembling lampbrush loops and polytene puffs. The extension and shape of transcription loops suggest their intrinsic stiffness, which we attribute to decoration with multiple voluminous nascent ribonucleoproteins. Our data contradict the model of transcription factories and suggest that although microscopically resolvable transcription loops are specific for long highly expressed genes, the mechanisms underlying their formation could represent a general aspect of eukaryotic transcription.
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Affiliation(s)
- Susanne Leidescher
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Johannes Ribisel
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Simon Ullrich
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Yana Feodorova
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Department of Medical Biology, Medical University of Plovdiv; Division of Molecular and Regenerative Medicine, Research Institute at Medical University of Plovdiv, Plovdiv, Bulgaria
| | - Erica Hildebrand
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Sebastian Bultmann
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Stephanie Link
- BioMedizinisches Center, Ludwig-Maximilians University Munich, Planegg-Martinsried, Germany
| | - Katharina Thanisch
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.,Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Christopher Mulholland
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Heinrich Leonhardt
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany
| | - Leonid Mirny
- Institute for Medical Engineering and Science, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Irina Solovei
- Department of Biology II, Biozentrum, Ludwig-Maximilians University Munich (LMU), Planegg-Martinsried, Germany.
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4
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Liu Y, Xiao J, Zhang B, Shelite TR, Su Z, Chang Q, Judy B, Li X, Drelich A, Bei J, Zhou Y, Zheng J, Jin Y, Rossi SL, Tang SJ, Wakamiya M, Saito T, Ksiazek T, Kaphalia B, Gong B. Increased talin-vinculin spatial proximities in livers in response to spotted fever group rickettsial and Ebola virus infections. J Transl Med 2020; 100:1030-1041. [PMID: 32238906 PMCID: PMC7111589 DOI: 10.1038/s41374-020-0420-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 03/12/2020] [Accepted: 03/12/2020] [Indexed: 12/17/2022] Open
Abstract
Talin and vinculin, both actin-cytoskeleton-related proteins, have been documented to participate in establishing bacterial infections, respectively, as the adapter protein to mediate cytoskeleton-driven dynamics of the plasma membrane. However, little is known regarding the potential role of the talin-vinculin complex during spotted fever group rickettsial and Ebola virus infections, two dreadful infectious diseases in humans. Many functional properties of proteins are determined by their participation in protein-protein complexes, in a temporal and/or spatial manner. To resolve the limitation of application in using mouse primary antibodies on archival, multiple formalin-fixed mouse tissue samples, which were collected from experiments requiring high biocontainment, we developed a practical strategic proximity ligation assay (PLA) capable of employing one primary antibody raised in mouse to probe talin-vinculin spatial proximal complex in mouse tissue. We observed an increase of talin-vinculin spatial proximities in the livers of spotted fever Rickettsia australis or Ebola virus-infected mice when compared with mock mice. Furthermore, using EPAC1-knockout mice, we found that deletion of EPAC1 could suppress the formation of spatial proximal complex of talin-vinculin in rickettsial infections. In addition, we observed increased colocalization between spatial proximity of talin-vinculin and filamentous actin-specific phalloidin staining in single survival mouse from an ordinarily lethal dose of rickettsial or Ebola virus infection. These findings may help to delineate a fresh insight into the mechanisms underlying liver specific pathogenesis during infection with spotted fever rickettsia or Ebola virus in the mouse model.
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Affiliation(s)
- Yakun Liu
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Jie Xiao
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Ben Zhang
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Thomas R. Shelite
- 0000 0001 1547 9964grid.176731.5Department of Internal Medicine, Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Zhengchen Su
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Qing Chang
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Barbara Judy
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Xiang Li
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Aleksandra Drelich
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Jiani Bei
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA ,0000 0004 0532 1428grid.265231.1Present Address: Life Science Department, Tunghai University, Taichung City, Taiwan
| | - Yixuan Zhou
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA ,0000 0004 0369 1599grid.411525.6Present Address: Department of Cardiovascular Surgery, Changhai Hospital, Shanghai, China
| | - Junying Zheng
- 0000 0001 1547 9964grid.176731.5Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Yang Jin
- 0000 0004 1936 7558grid.189504.1Division of Pulmonary and Critical Care Medicine, Department of Medicine, Boston University Medical Campus, Boston, MA USA
| | - Shannan L. Rossi
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Shao-Jun Tang
- 0000 0001 1547 9964grid.176731.5Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Maki Wakamiya
- 0000 0001 1547 9964grid.176731.5Department of Neurology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Tais Saito
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Thomas Ksiazek
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Bhupendra Kaphalia
- 0000 0001 1547 9964grid.176731.5Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555 USA
| | - Bin Gong
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, 77555, USA.
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5
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Subramanian K, Weigert M, Borsch O, Petzold H, Garcia-Ulloa A, Myers EW, Ader M, Solovei I, Kreysing M. Rod nuclear architecture determines contrast transmission of the retina and behavioral sensitivity in mice. eLife 2019; 8:49542. [PMID: 31825309 PMCID: PMC6974353 DOI: 10.7554/elife.49542] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 12/11/2019] [Indexed: 01/06/2023] Open
Abstract
Rod photoreceptors of nocturnal mammals display a striking inversion of nuclear architecture, which has been proposed as an evolutionary adaptation to dark environments. However, the nature of visual benefits and the underlying mechanisms remains unclear. It is widely assumed that improvements in nocturnal vision would depend on maximization of photon capture at the expense of image detail. Here, we show that retinal optical quality improves 2-fold during terminal development, and that this enhancement is caused by nuclear inversion. We further demonstrate that improved retinal contrast transmission, rather than photon-budget or resolution, enhances scotopic contrast sensitivity by 18–27%, and improves motion detection capabilities up to 10-fold in dim environments. Our findings therefore add functional significance to a prominent exception of nuclear organization and establish retinal contrast transmission as a decisive determinant of mammalian visual perception.
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Affiliation(s)
- Kaushikaram Subramanian
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany.,Cluster of Excellence, Physics of Life, Technische Universität Dresden, Dresden, Germany
| | - Martin Weigert
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany.,Cluster of Excellence, Physics of Life, Technische Universität Dresden, Dresden, Germany
| | - Oliver Borsch
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Heike Petzold
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | | - Eugene W Myers
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany.,Cluster of Excellence, Physics of Life, Technische Universität Dresden, Dresden, Germany.,Department of Computer Science, Technische Universität Dresden, Dresden, Germany
| | - Marius Ader
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, Dresden, Germany
| | - Irina Solovei
- Biozentrum, Ludwig Maximilians Universität, München, Germany
| | - Moritz Kreysing
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Center for Systems Biology Dresden, Dresden, Germany.,Cluster of Excellence, Physics of Life, Technische Universität Dresden, Dresden, Germany
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6
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Heterochromatin drives compartmentalization of inverted and conventional nuclei. Nature 2019; 570:395-399. [PMID: 31168090 DOI: 10.1038/s41586-019-1275-3] [Citation(s) in RCA: 345] [Impact Index Per Article: 69.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/26/2019] [Indexed: 01/18/2023]
Abstract
The nucleus of mammalian cells displays a distinct spatial segregation of active euchromatic and inactive heterochromatic regions of the genome1,2. In conventional nuclei, microscopy shows that euchromatin is localized in the nuclear interior and heterochromatin at the nuclear periphery1,2. Genome-wide chromosome conformation capture (Hi-C) analyses show this segregation as a plaid pattern of contact enrichment within euchromatin and heterochromatin compartments3, and depletion between them. Many mechanisms for the formation of compartments have been proposed, such as attraction of heterochromatin to the nuclear lamina2,4, preferential attraction of similar chromatin to each other1,4-12, higher levels of chromatin mobility in active chromatin13-15 and transcription-related clustering of euchromatin16,17. However, these hypotheses have remained inconclusive, owing to the difficulty of disentangling intra-chromatin and chromatin-lamina interactions in conventional nuclei18. The marked reorganization of interphase chromosomes in the inverted nuclei of rods in nocturnal mammals19,20 provides an opportunity to elucidate the mechanisms that underlie spatial compartmentalization. Here we combine Hi-C analysis of inverted rod nuclei with microscopy and polymer simulations. We find that attractions between heterochromatic regions are crucial for establishing both compartmentalization and the concentric shells of pericentromeric heterochromatin, facultative heterochromatin and euchromatin in the inverted nucleus. When interactions between heterochromatin and the lamina are added, the same model recreates the conventional nuclear organization. In addition, our models allow us to rule out mechanisms of compartmentalization that involve strong euchromatin interactions. Together, our experiments and modelling suggest that attractions between heterochromatic regions are essential for the phase separation of the active and inactive genome in inverted and conventional nuclei, whereas interactions of the chromatin with the lamina are necessary to build the conventional architecture from these segregated phases.
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7
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Zlotina A, Maslova A, Kosyakova N, Al-Rikabi ABH, Liehr T, Krasikova A. Heterochromatic regions in Japanese quail chromosomes: comprehensive molecular-cytogenetic characterization and 3D mapping in interphase nucleus. Chromosome Res 2018; 27:253-270. [DOI: 10.1007/s10577-018-9597-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 12/01/2018] [Accepted: 12/04/2018] [Indexed: 11/29/2022]
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8
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Singh RK, Diaz PE, Binette F, Nasonkin IO. Immunohistochemical Detection of 5-Methylcytosine and 5-Hydroxymethylcytosine in Developing and Postmitotic Mouse Retina. J Vis Exp 2018. [PMID: 30222161 PMCID: PMC6235063 DOI: 10.3791/58274] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The epigenetics of retinal development is a well-studied research field, which promises to bring a new level of understanding about the mechanisms of a variety of human retinal degenerative diseases and pinpoint new treatment approaches. The nuclear architecture of mouse retina is organized in two different patterns: conventional and inverted. Conventional pattern is universal where heterochromatin is localized to the periphery of the nucleus, while active euchromatin resides in the nuclear interior. In contrast, inverted nuclear pattern is unique to the adult rod photoreceptor cell nuclei where heterochromatin localizes to the nuclear center, and euchromatin resides in the nuclear periphery. DNA methylation is predominantly observed in chromocenters. DNA methylation is a dynamic covalent modification on the cytosine residues (5-methylcytosine, 5mC) of CpG dinucleotides that are enriched in the promoter regions of many genes. Three DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) participate in methylation of DNA during development. Detecting 5mC with immunohistochemical techniques is very challenging, contributing to variability in results, as all DNA bases including 5mC modified bases are hidden within the double-stranded DNA helix. However, detailed delineation of 5mC distribution during development is very informative. Here, we describe a reproducible technique for robust immunohistochemical detection of 5mC and another epigenetic DNA marker 5-hydroxymethylcytosine (5hmC), which colocalizes with the "open", transcriptionally active chromatin in developing and postmitotic mouse retina.
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9
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Müller B, Ellinwood NM, Lorenz B, Stieger K. Detection of DNA Double Strand Breaks by γH2AX Does Not Result in 53bp1 Recruitment in Mouse Retinal Tissues. Front Neurosci 2018; 12:286. [PMID: 29765300 PMCID: PMC5938408 DOI: 10.3389/fnins.2018.00286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/11/2018] [Indexed: 12/11/2022] Open
Abstract
Gene editing is an attractive potential treatment of inherited retinopathies. However, it often relies on endogenous DNA repair. Retinal DNA repair is incompletely characterized in humans and animal models. We investigated recruitment of the double stranded break (DSB) repair complex of γH2AX and 53bp1 in both developing and mature mouse neuroretinas. We evaluated the immunofluorescent retinal expression of these proteins during development (P07-P30) in normal and retinal degeneration models, as well as in potassium bromate induced DSB repair in normal adult (3 months) retinal explants. The two murine retinopathy models used had different mutations in Pde6b: the severe rd1 and the milder rd10 models. Compared to normal adult retina, we found increased numbers of γH2AX positive foci in all retinal neurons of the developing retina in both model and control retinas, as well as in wild type untreated retinal explant cultures. In contrast, the 53bp1 staining of the retina differed both in amount and character between cell types at all ages and in all model systems. There was strong pan nuclear staining in ganglion, amacrine, and horizontal cells, and cone photoreceptors, which was attenuated. Rod photoreceptors did not stain unequivocally. In all samples, 53bp1 stained foci only rarely occurred. Co-localization of 53bp1 and γH2AX staining was a very rare event (< 1% of γH2AX foci in the ONL and < 3% in the INL), suggesting the potential for alternate DSB sensing and repair proteins in the murine retina. At a minimum, murine retinal DSB repair does not appear to follow canonical pathways, and our findings suggests further investigation is warranted.
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Affiliation(s)
- Brigitte Müller
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - N M Ellinwood
- Department of Animal Science and Veterinary Clinical Science, Iowa State University, Ames, IA, United States
| | - Birgit Lorenz
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Knut Stieger
- Department of Ophthalmology, Justus-Liebig-University Giessen, Giessen, Germany
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10
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van de Werken HJG, Haan JC, Feodorova Y, Bijos D, Weuts A, Theunis K, Holwerda SJB, Meuleman W, Pagie L, Thanisch K, Kumar P, Leonhardt H, Marynen P, van Steensel B, Voet T, de Laat W, Solovei I, Joffe B. Small chromosomal regions position themselves autonomously according to their chromatin class. Genome Res 2017; 27:922-933. [PMID: 28341771 PMCID: PMC5453326 DOI: 10.1101/gr.213751.116] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 03/22/2017] [Indexed: 11/24/2022]
Abstract
The spatial arrangement of chromatin is linked to the regulation of nuclear processes. One striking aspect of nuclear organization is the spatial segregation of heterochromatic and euchromatic domains. The mechanisms of this chromatin segregation are still poorly understood. In this work, we investigated the link between the primary genomic sequence and chromatin domains. We analyzed the spatial intranuclear arrangement of a human artificial chromosome (HAC) in a xenospecific mouse background in comparison to an orthologous region of native mouse chromosome. The two orthologous regions include segments that can be assigned to three major chromatin classes according to their gene abundance and repeat repertoire: (1) gene-rich and SINE-rich euchromatin; (2) gene-poor and LINE/LTR-rich heterochromatin; and (3) gene-depleted and satellite DNA-containing constitutive heterochromatin. We show, using fluorescence in situ hybridization (FISH) and 4C-seq technologies, that chromatin segments ranging from 0.6 to 3 Mb cluster with segments of the same chromatin class. As a consequence, the chromatin segments acquire corresponding positions in the nucleus irrespective of their chromosomal context, thereby strongly suggesting that this is their autonomous property. Interactions with the nuclear lamina, although largely retained in the HAC, reveal less autonomy. Taken together, our results suggest that building of a functional nucleus is largely a self-organizing process based on mutual recognition of chromosome segments belonging to the major chromatin classes.
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Affiliation(s)
- Harmen J G van de Werken
- Cancer Computational Biology Center, Erasmus MC Cancer Institute & Department of Urology, Erasmus MC Cancer Institute, Erasmus University Medical Center, 3015 CN, Rotterdam, The Netherlands.,Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Josien C Haan
- Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Yana Feodorova
- Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Dominika Bijos
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - An Weuts
- Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Koen Theunis
- Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Sjoerd J B Holwerda
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Wouter Meuleman
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Ludo Pagie
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Katharina Thanisch
- Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Parveen Kumar
- Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Heinrich Leonhardt
- Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Peter Marynen
- Human Genome Laboratory, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Bas van Steensel
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Thierry Voet
- Laboratory of Reproductive Genomics, Department of Human Genetics, KU Leuven, Leuven, 3000, Belgium
| | - Wouter de Laat
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Irina Solovei
- Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
| | - Boris Joffe
- Department of Biology II, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
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11
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Thanisch K, Song C, Engelkamp D, Koch J, Wang A, Hallberg E, Foisner R, Leonhardt H, Stewart CL, Joffe B, Solovei I. Nuclear envelope localization of LEMD2 is developmentally dynamic and lamin A/C dependent yet insufficient for heterochromatin tethering. Differentiation 2017; 94:58-70. [PMID: 28056360 DOI: 10.1016/j.diff.2016.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/05/2016] [Accepted: 12/06/2016] [Indexed: 11/28/2022]
Abstract
Peripheral heterochromatin in mammalian nuclei is tethered to the nuclear envelope by at least two mechanisms here referred to as the A- and B-tethers. The A-tether includes lamins A/C and additional unknown components presumably INM protein(s) interacting with both lamins A/C and chromatin. The B-tether includes the inner nuclear membrane (INM) protein Lamin B-receptor, which binds B-type lamins and chromatin. Generally, at least one of the tethers is always present in the nuclear envelope of mammalian cells. Deletion of both causes the loss of peripheral heterochromatin and consequently inversion of the entire nuclear architecture, with this occurring naturally in rod photoreceptors of nocturnal mammals. The tethers are differentially utilized during development, regulate gene expression in opposite manners, and play an important role during cell differentiation. Here we aimed to identify the unknown chromatin binding component(s) of the A-tether. We analyzed 10 mouse tissues by immunostaining with antibodies against 7 INM proteins and found that every cell type has specific, although differentially and developmentally regulated, sets of these proteins. In particular, we found that INM protein LEMD2 is concomitantly expressed with A-type lamins in various cell types but is lacking in inverted nuclei of rod cells. Truncation or deletion of Lmna resulted in the downregulation and mislocalization of LEMD2, suggesting that the two proteins interact and pointing at LEMD2 as a potential chromatin binding mediator of the A-tether. Using nuclei of mouse rods as an experimental model lacking peripheral heterochromatin, we expressed a LEMD2 transgene alone or in combination with lamin C in these cells and observed no restoration of peripheral heterochromatin in either case. We conclude that in contrary to the B-tether, the A-tether has a more intricate composition and consists of multiple components that presumably vary, at differing degrees of redundancy, between cell types and differentiation stages.
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Affiliation(s)
- Katharina Thanisch
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Congdi Song
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Dieter Engelkamp
- Transgenic Service Facility, BTE, Franz-Penzoldt-Centre, Friedrich-Alexander-University of Erlangen-Nürnberg, Erwin-Rommel-Str.3, D-91058 Erlangen, Germany
| | - Jeannette Koch
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Audrey Wang
- Institute of Medical Biology, 8A Biomedical Grove and Dept of Biological Sciences, NUS, 138648, Singapore
| | - Einar Hallberg
- Department of Neurochemistry, Stockholm University, Se-106 91 Stockholm, Sweden
| | - Roland Foisner
- Max F. Perutz Laboratories, Medical University of Vienna, Vienna Biocenter (VBC), Dr. Bohr-Gasse 9, A-1030 Vienna, Austria
| | - Heinrich Leonhardt
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Colin L Stewart
- Institute of Medical Biology, 8A Biomedical Grove and Dept of Biological Sciences, NUS, 138648, Singapore.
| | - Boris Joffe
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Irina Solovei
- Department of Biology II, Ludwig-Maximilians-University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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12
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Distribution of histone H4 modifications as revealed by a panel of specific monoclonal antibodies. Chromosome Res 2015; 23:753-66. [PMID: 26343042 PMCID: PMC4666908 DOI: 10.1007/s10577-015-9486-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 08/18/2015] [Accepted: 08/20/2015] [Indexed: 12/24/2022]
Abstract
Post-translational histone modifications play a critical role in genome functions such as epigenetic gene regulation and genome maintenance. The tail of the histone H4 N-terminus contains several amino acids that can be acetylated and methylated. Some of these modifications are known to undergo drastic changes during the cell cycle. In this study, we generated a panel of mouse monoclonal antibodies against histone H4 modifications, including acetylation at K5, K8, K12, and K16, and different levels of methylation at K20. Their specificity was evaluated by ELISA and immunoblotting using synthetic peptide and recombinant proteins that harbor specific modifications or amino acid substitutions. Immunofluorescence confirmed the characteristic distributions of target modifications. An H4K5 acetylation (H4K5ac)-specific antibody CMA405 reacted with K5ac only when the neighboring K8 was unacetylated. This unique feature allowed us to detect newly assembled H4, which is diacetylated at K5 and K12, and distinguish it from hyperacetylated H4, where K5 and K8 are both acetylated. Chromatin immunoprecipiation combined with deep sequencing (ChIP-seq) revealed that acetylation of both H4K8 and H4K16 were enriched around transcription start sites. These extensively characterized and highly specific antibodies will be useful for future epigenetics and epigenome studies.
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Kimura H, Hayashi-Takanaka Y, Stasevich TJ, Sato Y. Visualizing posttranslational and epigenetic modifications of endogenous proteins in vivo. Histochem Cell Biol 2015; 144:101-9. [PMID: 26138929 PMCID: PMC4522274 DOI: 10.1007/s00418-015-1344-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2015] [Indexed: 01/29/2023]
Abstract
Protein localization and dynamics can now be visualized in living cells using the fluorescent protein fusion technique, but it is still difficult to selectively detect molecules with a specific function. As a posttranslational protein modification is often associated with a specific function, marking specifically modified protein molecules in living cells is a way to track an important fraction of protein. In the nucleus, histones are subjected to a variety of modifications such as acetylation and methylation that are associated with epigenetic gene regulation. RNA polymerase II, an enzyme that transcribes genes, is also differentially phosphorylated during the initiation and elongation of transcription. To understand the mechanism of gene regulation in vivo, we have developed methods to track histone and RNA polymerase II modifications using probes derived from modification-specific monoclonal antibodies. In Fab-based live endogenous modification labeling (FabLEM), fluorescently labeled antigen-binding fragments (Fabs) are loaded into cells. Fabs bind to target modifications in the nucleus with a binding time of a second to tens of seconds, and so the modification can be tracked without disturbing cell function. For tracking over longer periods of time or in living animals, we have also developed a genetically encoded system to express a modification-specific intracellular antibody (mintbody). Transgenic fruit fly and zebrafish that express histone H3 Lys9 acetylation-specific mintbody developed normally and remain fertile, suggesting that visualizing histone modifications in any tissue in live animals has become possible. These live cell modification tracking techniques will facilitate future studies on epigenetic regulation related to development, differentiation, and disease. Moreover, these techniques can be applied to any other protein modification, opening up new avenues in broad areas in biology and medicine.
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Affiliation(s)
- Hiroshi Kimura
- Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan,
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Feodorova Y, Koch M, Bultman S, Michalakis S, Solovei I. Quick and reliable method for retina dissociation and separation of rod photoreceptor perikarya from adult mice. MethodsX 2015; 2:39-46. [PMID: 26150970 PMCID: PMC4487332 DOI: 10.1016/j.mex.2015.01.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/14/2015] [Indexed: 12/20/2022] Open
Abstract
A pure and abundant population of adult rod perikarya can be exploited in different studies concerning nuclear functions such as gene expression analyses which aim at elucidating the relationship between cell type and disease [1]. Sorting is based either on specific cell-surface markers or fluorescently labeled reporter proteins. Here, we describe a simple and reliable method for separation of rod photoreceptor perikarya without the use of staining procedures or transgenic mice. This method is limited, however, to sorting rod photoreceptors from adult mouse retina. Mature rods possess an inverted nuclear architecture which is determined by the optical functions of these nuclei [2]. The high backscatter of heterochromatin in the core of the nucleus can be used as a selection criterion for FAC-sorting by forward and sideward scatter. The procedure for retina dissociation using the Papain Dissociation System (Wothington Biochemical Corporation) was optimized. An easy to follow step-by-step protocol for retina dissociation was devised. Rod perikarya were FAC-sorted by forward and sideward scatter based solely on the high backscatter of heterochromatin in their nuclei.
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Affiliation(s)
- Yana Feodorova
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany ; Department of Medical Biology, Medical University-Plovdiv, Blvd. Vasil Aprilov 15A, 4000 Plovdiv, Bulgaria
| | - Mirja Koch
- Center for Integrated Protein Science Munich CIPSM at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Sebastian Bultman
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science Munich CIPSM at the Department of Pharmacy - Center for Drug Research, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Irina Solovei
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
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15
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Song C, Feodorova Y, Guy J, Peichl L, Jost KL, Kimura H, Cardoso MC, Bird A, Leonhardt H, Joffe B, Solovei I. DNA methylation reader MECP2: cell type- and differentiation stage-specific protein distribution. Epigenetics Chromatin 2014; 7:17. [PMID: 25170345 PMCID: PMC4148084 DOI: 10.1186/1756-8935-7-17] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Accepted: 07/23/2014] [Indexed: 11/21/2022] Open
Abstract
Background Methyl-CpG binding protein 2 (MECP2) is a protein that specifically binds methylated DNA, thus regulating transcription and chromatin organization. Mutations in the gene have been identified as the principal cause of Rett syndrome, a severe neurological disorder. Although the role of MECP2 has been extensively studied in nervous tissues, still very little is known about its function and cell type specific distribution in other tissues. Results Using immunostaining on tissue cryosections, we characterized the distribution of MECP2 in 60 cell types of 16 mouse neuronal and non-neuronal tissues. We show that MECP2 is expressed at a very high level in all retinal neurons except rod photoreceptors. The onset of its expression during retina development coincides with massive synapse formation. In contrast to astroglia, retinal microglial cells lack MECP2, similar to microglia in the brain, cerebellum, and spinal cord. MECP2 is also present in almost all non-neural cell types, with the exception of intestinal epithelial cells, erythropoietic cells, and hair matrix keratinocytes. Our study demonstrates the role of MECP2 as a marker of the differentiated state in all studied cells other than oocytes and spermatogenic cells. MECP2-deficient male (Mecp2-/y) mice show no apparent defects in the morphology and development of the retina. The nuclear architecture of retinal neurons is also unaffected as the degree of chromocenter fusion and the distribution of major histone modifications do not differ between Mecp2-/y and Mecp2wt mice. Surprisingly, the absence of MECP2 is not compensated by other methyl-CpG binding proteins. On the contrary, their mRNA levels were downregulated in Mecp2-/y mice. Conclusions MECP2 is almost universally expressed in all studied cell types with few exceptions, including microglia. MECP2 deficiency does not change the nuclear architecture and epigenetic landscape of retinal cells despite the missing compensatory expression of other methyl-CpG binding proteins. Furthermore, retinal development and morphology are also preserved in Mecp2-null mice. Our study reveals the significance of MECP2 function in cell differentiation and sets the basis for future investigations in this direction.
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Affiliation(s)
- Congdi Song
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Yana Feodorova
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Jacky Guy
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3JR Edinburgh, UK
| | - Leo Peichl
- Max Planck Institute for Brain Research, Max-von-Laue-Str. 4, Frankfurt am Main 60438, Germany
| | - Katharina Laurence Jost
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstr. 10, Darmstadt 64287, Germany
| | - Hiroshi Kimura
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, 565-0871 Suita, Osaka, Japan
| | - Maria Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technische Universität Darmstadt, Schnittspahnstr. 10, Darmstadt 64287, Germany
| | - Adrian Bird
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, EH9 3JR Edinburgh, UK
| | - Heinrich Leonhardt
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Boris Joffe
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
| | - Irina Solovei
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
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Search for Conditions to Detect Epigenetic Marks and Nuclear Proteins in Immunostaining of the Testis and Cartilage. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/658293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The localization of nuclear proteins and modified histone tails changes during cell differentiation at the tissue as well as at the cellular level. Immunostaining in paraffin sections is the most powerful approach available to evaluate protein localization. Since nuclear proteins are sensitive to fixation, immunohistochemical conditions should be optimized in light of the particular antibodies and tissues employed. In this study, we searched for optimal conditions to detect histone modification at histone H3 lysine 9 (H3K9) and H3K9 methyltransferase G9a in the testis and cartilage in paraffin sections. In the testis, antigen retrieval (AR) was indispensable for detecting H3K9me1 and me3, G9a, and nuclear protein proliferating cell nuclear antigen (PCNA). With AR, shorter fixation times yielded better results for the detection of G9a and PCNA. Without AR, H3K9me2 and H3K9ac could be detected at shorter fixation times in primary spermatocytes of the testis. In contrast to the testis, all antibodies tested could detect their epitopes irrespective of AR application in the growth plate cartilage. Thus, conditions for the detection of epigenetic marks and nuclear proteins should be optimized in consideration of fixation time and AR application in different tissues and antibodies.
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Epigenetics of eu- and heterochromatin in inverted and conventional nuclei from mouse retina. Chromosome Res 2013; 21:535-54. [PMID: 23996328 DOI: 10.1007/s10577-013-9375-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/16/2013] [Accepted: 07/17/2013] [Indexed: 12/20/2022]
Abstract
To improve light propagation through the retina, the rod nuclei of nocturnal mammals are uniquely changed compared to the nuclei of other cells. In particular, the main classes of chromatin are segregated in them and form regular concentric shells in order; inverted in comparison to conventional nuclei. A broad study of the epigenetic landscape of the inverted and conventional mouse retinal nuclei indicated several differences between them and several features of general interest for the organization of the mammalian nuclei. In difference to nuclei with conventional architecture, the packing density of pericentromeric satellites and LINE-rich chromatin is similar in inverted rod nuclei; euchromatin has a lower packing density in both cases. A high global chromatin condensation in rod nuclei minimizes the structural difference between active and inactive X chromosome homologues. DNA methylation is observed primarily in the chromocenter, Dnmt1 is primarily associated with the euchromatic shell. Heterochromatin proteins HP1-alpha and HP1-beta localize in heterochromatic shells, whereas HP1-gamma is associated with euchromatin. For most of the 25 studied histone modifications, we observed predominant colocalization with a certain main chromatin class. Both inversions in rod nuclei and maintenance of peripheral heterochromatin in conventional nuclei are not affected by a loss or depletion of the major silencing core histone modifications in respective knock-out mice, but for different reasons. Maintenance of peripheral heterochromatin appears to be ensured by redundancy both at the level of enzymes setting the epigenetic code (writers) and the code itself, whereas inversion in rods rely on the absence of the peripheral heterochromatin tethers (absence of code readers).
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Joffe B, Peichl L, Hendrickson A, Leonhardt H, Solovei I. Diurnality and Nocturnality in Primates: An Analysis from the Rod Photoreceptor Nuclei Perspective. Evol Biol 2013. [DOI: 10.1007/s11692-013-9240-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Solovei I, Wang AS, Thanisch K, Schmidt CS, Krebs S, Zwerger M, Cohen TV, Devys D, Foisner R, Peichl L, Herrmann H, Blum H, Engelkamp D, Stewart CL, Leonhardt H, Joffe B. LBR and lamin A/C sequentially tether peripheral heterochromatin and inversely regulate differentiation. Cell 2013; 152:584-98. [PMID: 23374351 DOI: 10.1016/j.cell.2013.01.009] [Citation(s) in RCA: 556] [Impact Index Per Article: 50.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 09/14/2012] [Accepted: 01/07/2013] [Indexed: 01/26/2023]
Abstract
Eukaryotic cells have a layer of heterochromatin at the nuclear periphery. To investigate mechanisms regulating chromatin distribution, we analyzed heterochromatin organization in different tissues and species, including mice with mutations in the lamin B receptor (Lbr) and lamin A (Lmna) genes that encode nuclear envelope (NE) proteins. We identified LBR- and lamin-A/C-dependent mechanisms tethering heterochromatin to the NE. The two tethers are sequentially used during cellular differentiation and development: first the LBR- and then the lamin-A/C-dependent tether. The absence of both LBR and lamin A/C leads to loss of peripheral heterochromatin and an inverted architecture with heterochromatin localizing to the nuclear interior. Myoblast transcriptome analyses indicated that selective disruption of the LBR- or lamin-A-dependent heterochromatin tethers have opposite effects on muscle gene expression, either increasing or decreasing, respectively. These results show how changes in NE composition contribute to regulating heterochromatin positioning, gene expression, and cellular differentiation during development.
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Affiliation(s)
- Irina Solovei
- Department of Biology II, Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians University Munich, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany
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