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Lakadamyali M. From feulgen to modern methods: marking a century of DNA imaging advances. Histochem Cell Biol 2024; 162:13-22. [PMID: 38753186 PMCID: PMC11227465 DOI: 10.1007/s00418-024-02291-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2024] [Indexed: 07/07/2024]
Abstract
The mystery of how human DNA is compactly packaged into a nucleus-a space a hundred thousand times smaller-while still allowing for the regulation of gene function, has long been one of the greatest enigmas in cell biology. This puzzle is gradually being solved, thanks in part to the advent of new technologies. Among these, innovative genome-labeling techniques combined with high-resolution imaging methods have been pivotal. These methods facilitate the visualization of DNA within intact nuclei and have significantly contributed to our current understanding of genome organization. This review will explore various labeling and imaging approaches that are revolutionizing our understanding of the three-dimensional organization of the genome, shedding light on the relationship between its structure and function.
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Affiliation(s)
- Melike Lakadamyali
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA.
- Perelman School of Medicine, Epigenetics Institute, University of Pennsylvania, Philadelphia, USA.
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2
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Almansour F, Keikhosravi A, Pegoraro G, Misteli T. Allele-level visualization of transcription and chromatin by high-throughput imaging. Histochem Cell Biol 2024; 162:65-77. [PMID: 38724854 PMCID: PMC11227451 DOI: 10.1007/s00418-024-02289-7] [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: 04/11/2024] [Indexed: 05/21/2024]
Abstract
The spatial arrangement of the genome within the nucleus is a pivotal aspect of cellular organization and function with implications for gene expression and regulation. While all genome organization features, such as loops, domains, and radial positioning, are nonrandom, they are characterized by a high degree of single-cell variability. Imaging approaches are ideally suited to visualize, measure, and study single-cell heterogeneity in genome organization. Here, we describe two methods for the detection of DNA and RNA of individual gene alleles by fluorescence in situ hybridization (FISH) in a high-throughput format. We have optimized combined DNA/RNA FISH approaches either using simultaneous or sequential detection of DNA and nascent RNA. These optimized DNA and RNA FISH protocols were implemented in a 384-well plate format alongside automated image and data analysis and enable accurate detection of individual gene alleles and their gene expression status across a large cell population. We successfully visualized MYC and EGFR DNA and nascent RNA with allele-level resolution in multiple cell types, and we determined the radial position of active and inactive MYC and EGFR alleles. These optimized DNA/RNA detection approaches are versatile and sensitive tools for mapping of chromatin features and gene activity at the single-allele level and at high throughput.
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Affiliation(s)
- Faisal Almansour
- Cell Biology of Genomes, National Cancer Institute, National Institute of Health, Bethesda, MD, 20892, USA
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical School, Washington, DC, 20057, USA
| | - Adib Keikhosravi
- High-Throughput Imaging Facility, National Cancer Institute, National Institute of Health, Bethesda, MD, 20892, USA
| | - Gianluca Pegoraro
- High-Throughput Imaging Facility, National Cancer Institute, National Institute of Health, Bethesda, MD, 20892, USA
| | - Tom Misteli
- Cell Biology of Genomes, National Cancer Institute, National Institute of Health, Bethesda, MD, 20892, USA.
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3
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Mian Y, Wang L, Keikhosravi A, Guo K, Misteli T, Arda HE, Finn EH. Cell type- and transcription-independent spatial proximity between enhancers and promoters. Mol Biol Cell 2024; 35:ar96. [PMID: 38717453 PMCID: PMC11244156 DOI: 10.1091/mbc.e24-02-0082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024] Open
Abstract
Cell type-specific enhancers are critically important for lineage specification. The mechanisms that determine cell-type specificity of enhancer activity, however, are not fully understood. Most current models for how enhancers function invoke physical proximity between enhancer elements and their target genes. Here, we use an imaging-based approach to examine the spatial relationship of cell type-specific enhancers and their target genes with single-cell resolution. Using high-throughput microscopy, we measure the spatial distance from target promoters to their cell type-specific active and inactive enhancers in individual pancreatic cells derived from distinct lineages. We find increased proximity of all promoter-enhancer pairs relative to non-enhancer pairs separated by similar genomic distances. Strikingly, spatial proximity between enhancers and target genes was unrelated to tissue-specific enhancer activity. Furthermore, promoter-enhancer proximity did not correlate with the expression status of target genes. Our results suggest that promoter-enhancer pairs exist in a distinctive chromatin environment but that genome folding is not a universal driver of cell-type specificity in enhancer function.
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Affiliation(s)
- Yasmine Mian
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Li Wang
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Adib Keikhosravi
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Konnie Guo
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Tom Misteli
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - H Efsun Arda
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
| | - Elizabeth H Finn
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
- Cell Cycle and Cancer Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104
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4
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Shim AR, Frederick J, Pujadas EM, Kuo T, Ye IC, Pritchard JA, Dunton CL, Gonzalez PC, Acosta N, Jain S, Anthony NM, Almassalha LM, Szleifer I, Backman V. Formamide denaturation of double-stranded DNA for fluorescence in situ hybridization (FISH) distorts nanoscale chromatin structure. PLoS One 2024; 19:e0301000. [PMID: 38805476 PMCID: PMC11132451 DOI: 10.1371/journal.pone.0301000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 03/10/2024] [Indexed: 05/30/2024] Open
Abstract
As imaging techniques rapidly evolve to probe nanoscale genome organization at higher resolution, it is critical to consider how the reagents and procedures involved in sample preparation affect chromatin at the relevant length scales. Here, we investigate the effects of fluorescent labeling of DNA sequences within chromatin using the gold standard technique of three-dimensional fluorescence in situ hybridization (3D FISH). The chemical reagents involved in the 3D FISH protocol, specifically formamide, cause significant alterations to the sub-200 nm (sub-Mbp) chromatin structure. Alternatively, two labeling methods that do not rely on formamide denaturation, resolution after single-strand exonuclease resection (RASER)-FISH and clustered regularly interspaced short palindromic repeats (CRISPR)-Sirius, had minimal impact on the three-dimensional organization of chromatin. We present a polymer physics-based analysis of these protocols with guidelines for their interpretation when assessing chromatin structure using currently available techniques.
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Affiliation(s)
- Anne R. Shim
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Jane Frederick
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Emily M. Pujadas
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Tiffany Kuo
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - I. Chae Ye
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Joshua A. Pritchard
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Cody L. Dunton
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Paola Carrillo Gonzalez
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Nicolas Acosta
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Surbhi Jain
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Nicholas M. Anthony
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
| | - Luay M. Almassalha
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
- Department of Gastroenterology and Hepatology, Northwestern Memorial Hospital, Chicago, Illinois, United States of America
| | - Igal Szleifer
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Department of Chemistry, Northwestern University, Evanston, Illinois, United States of America
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, Illinois, United States of America
- Center for Physical Genomics and Engineering, Northwestern University, Evanston, Illinois, United States of America
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois, United States of America
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5
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Almansour F, Keikhosravi A, Pegoraro G, Misteli T. Allele-level visualization of transcription and chromatin by high-throughput imaging. RESEARCH SQUARE 2024:rs.3.rs-3970096. [PMID: 38464289 PMCID: PMC10925428 DOI: 10.21203/rs.3.rs-3970096/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The spatial arrangement of the genome within the nucleus is a pivotal aspect of cellular organization and function with implications for gene expression and regulation. While all genome organization features, such as loops, domains, and radial positioning, are non-random, they are characterized by a high degree of single-cell variability. Imaging approaches are ideally suited to visualize, measure, and study single-cell heterogeneity in genome organization. Here, we describe two methods for the detection of DNA and RNA of individual gene alleles by fluorescence in situ hybridization (FISH) in a high-throughput format. We have optimized combined DNA/RNA FISH approaches either using simultaneous or sequential detection. These optimized DNA and RNA FISH protocols, implemented in a 384-well plate format alongside automated image and data analysis, enable accurate detection of chromatin loci and their gene expression status across a large cell population with allele-level resolution. We successfully visualized MYC and EGFR DNA and RNA in multiple cell types, and we determined the radial position of active and inactive MYC and EGFR alleles. These optimized DNA/RNA detection approaches are versatile and sensitive tools for mapping of chromatin features and gene activity at the single-allele level and at high throughput.
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Affiliation(s)
| | | | | | - Tom Misteli
- National Cancer Institute, National Institute of Health
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6
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Almansour F, Keikhosravi A, Pegoraro G, Misteli T. Allele-level visualization of transcription and chromatin by high-throughput imaging. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.19.580973. [PMID: 38529487 PMCID: PMC10962702 DOI: 10.1101/2024.02.19.580973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
The spatial arrangement of the genome within the nucleus is a pivotal aspect of cellular organization and function with implications for gene expression and regulation. While all genome organization features, such as loops, domains, and radial positioning, are non-random, they are characterized by a high degree of single-cell variability. Imaging approaches are ideally suited to visualize, measure, and study single-cell heterogeneity in genome organization. Here, we describe two methods for the detection of DNA and RNA of individual gene alleles by fluorescence in situ hybridization (FISH) in a high-throughput format. We have optimized combined DNA/RNA FISH approaches either using simultaneous or sequential detection. These optimized DNA and RNA FISH protocols, implemented in a 384-well plate format alongside automated image and data analysis, enable accurate detection of chromatin loci and their gene expression status across a large cell population with allele-level resolution. We successfully visualized MYC and EGFR DNA and RNA in multiple cell types, and we determined the radial position of active and inactive MYC and EGFR alleles. These optimized DNA/RNA detection approaches are versatile and sensitive tools for mapping of chromatin features and gene activity at the single-allele level and at high throughput.
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Affiliation(s)
- Faisal Almansour
- Cell Biology of Genomes, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University Medical School, Washington, DC, 20057, USA
| | - Adib Keikhosravi
- High-Throughput Imaging Facility, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA
| | - Gianluca Pegoraro
- High-Throughput Imaging Facility, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA
| | - Tom Misteli
- Cell Biology of Genomes, National Cancer Institute, National Institute of Health, Bethesda, MD 20892, USA
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7
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Ghule PN, Boyd JR, Kabala F, Fritz AJ, Bouffard NA, Gao C, Bright K, Macfarlane J, Seward DJ, Pegoraro G, Misteli T, Lian JB, Frietze S, Stein JL, van Wijnen AJ, Stein GS. Spatiotemporal higher-order chromatin landscape of human histone gene clusters at histone locus bodies during the cell cycle in breast cancer progression. Gene 2023; 872:147441. [PMID: 37094694 PMCID: PMC10370284 DOI: 10.1016/j.gene.2023.147441] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 04/26/2023]
Abstract
Human Histone Locus Bodies (HLBs) are nuclear subdomains comprised of clustered histone genes that are coordinately regulated throughout the cell cycle. We addressed temporal-spatial higher-order genome organization for time-dependent chromatin remodeling at HLBs that supports control of cell proliferation. Proximity distances of specific genomic contacts within histone gene clusters exhibit subtle changes during the G1 phase in MCF10 breast cancer progression model cell lines. This approach directly demonstrates that the two principal histone gene regulatory proteins, HINFP (H4 gene regulator) and NPAT, localize at chromatin loop anchor-points, denoted by CTCF binding, supporting the stringent requirement for histone biosynthesis to package newly replicated DNA as chromatin. We identified a novel enhancer region located ∼ 2 MB distal to histone gene sub-clusters on chromosome 6 that consistently makes genomic contacts with HLB chromatin and is bound by NPAT. During G1 progression the first DNA loops form between one of three histone gene sub-clusters bound by HINFP and the distal enhancer region. Our findings are consistent with a model that the HINFP/NPAT complex controls the formation and dynamic remodeling of higher-order genomic organization of histone gene clusters at HLBs in early to late G1 phase to support transcription of histone mRNAs in S phase.
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Affiliation(s)
- Prachi N Ghule
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Joseph R Boyd
- Department of Biomedical and Health Sciences and University of Vermont Cancer Center, College of Nursing and Health Sciences, University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Fleur Kabala
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Andrew J Fritz
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Nicole A Bouffard
- Microscopy Imaging Center, Center for Biomedical Shared Resources at the University of Vermont, 150 Firestone Building, 149 Beaumont Ave, Burlington, VT 05405, USA
| | - Cong Gao
- Department of Biomedical and Health Sciences and University of Vermont Cancer Center, College of Nursing and Health Sciences, University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Kathleen Bright
- Department of Biomedical and Health Sciences and University of Vermont Cancer Center, College of Nursing and Health Sciences, University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - Jill Macfarlane
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA
| | - David J Seward
- Department of Pathology and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Gianluca Pegoraro
- High-Throughput Imaging Facility (HiTIF), Center for Cancer Research (CCR), National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Tom Misteli
- Cell Biology of Genomes, Center for Cancer Research (CCR), National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Jane B Lian
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Seth Frietze
- Department of Biomedical and Health Sciences and University of Vermont Cancer Center, College of Nursing and Health Sciences, University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Janet L Stein
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Andre J van Wijnen
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
| | - Gary S Stein
- Department of Biochemistry and University of Vermont Cancer Center, Larner College of Medicine at the University of Vermont, 89 Beaumont Avenue, Burlington, VT 05405, USA.
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Choi M, Kwon H, Pak Y. Caveolin-2 in association with nuclear lamina controls adipocyte hypertrophy. FASEB J 2023; 37:e22745. [PMID: 36637913 DOI: 10.1096/fj.202201028rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 01/14/2023]
Abstract
Here, we identify that Caveolin-2 (Cav-2), an integral membrane protein, controls adipocyte hypertrophy in association with nuclear lamina. In the hypertrophy stage of adipogenesis, pY19-Cav-2 association with lamin A/C facilitated the disengagement of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ) from lamin A/C and repressed Cav-2 promoter at the nuclear periphery for epigenetic activation of Cav-2, and thereby promoted C/EBPα and PPARγ-induced adipocyte hypertrophy. Stable expression of Cav-2 was required and retained by phosphorylation, deubiquitination, and association with lamin A/C for the adipocyte hypertrophy. However, obese adipocytes exhibited augmented Cav-2 stability resulting from the up-regulation of lamin A/C over lamin B1, protein tyrosine phosphatase 1B (PTP1B), and nuclear deubiquitinating enzyme (DUB), Uchl5. Our findings show a novel epigenetic regulatory mechanism of adipocyte hypertrophy by Cav-2 at the nuclear periphery.
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Affiliation(s)
- Moonjeong Choi
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju, South Korea
| | - Hayeong Kwon
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju, South Korea
| | - Yunbae Pak
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju, South Korea
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9
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Choi M, Kwon H, Jeong K, Pak Y. Epigenetic regulation of Cebpb activation by pY19-Caveolin-2 at the nuclear periphery in association with the nuclear lamina. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2022; 1869:119363. [PMID: 36165916 DOI: 10.1016/j.bbamcr.2022.119363] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 08/22/2022] [Accepted: 09/11/2022] [Indexed: 06/16/2023]
Abstract
Here, we show that Caveolin-2 (Cav-2) is an epigenetic regulator for adipogenesis. Upon adipogenic stimulation, inner nuclear membrane (INM)-targeted pY19-Cav-2 interacted with lamin A/C to disengage the repressed Cebpb promoter from lamin A/C, which facilitated the Cebpb promoter association with lamin B1. Consequently, pY19-Cav-2 recruited lysine demethylase 4b (KDM4b) for demethylation of histone H3 lysine 9 trimethylation (H3K9me3) and histone acetyltransferase GCN5 for acetylation of H3K27, and subsequently RNA polymerase II (Pol II) on Cebpb promoter for epigenetic activation of Cebpb, to initiate adipogenesis. Cav-2 knock-down abrogated the Cebpb activation and blocked the Pparg2 and Cebpa activation. Re-expression of Cav-2 restored Cebpb activation and adipogenesis in Cav-2-deficient preadipocytes. Our data identify a new mechanism by which the epigenetic activation of Cebpb is controlled at the nuclear periphery to promote adipogenesis.
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Affiliation(s)
- Moonjeong Choi
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Hayeong Kwon
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Kyuho Jeong
- Department of Biochemistry, College of Medicine, Dongguk University, Gyeongju 38066, Republic of Korea
| | - Yunbae Pak
- Division of Life Science, Graduate School of Applied Life Science (BK21 Plus Program), PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea.
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10
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Finn EH, Misteli T. Nuclear position modulates long-range chromatin interactions. PLoS Genet 2022; 18:e1010451. [PMID: 36206323 PMCID: PMC9581366 DOI: 10.1371/journal.pgen.1010451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 10/19/2022] [Accepted: 09/28/2022] [Indexed: 11/18/2022] Open
Abstract
The human genome is non-randomly organized within the cell nucleus. Spatial mapping of genome folding by biochemical methods and imaging has revealed extensive variation in locus interaction frequencies between cells in a population and between homologs within an individual cell. Commonly used mapping approaches typically examine either the relative position of genomic sites to each other or the position of individual loci relative to nuclear landmarks. Whether the frequency of specific chromatin-chromatin interactions is affected by where in the nuclear space a locus is located is unknown. Here, we have simultaneously mapped at the single cell level the interaction frequencies and radial position of more than a hundred locus pairs using high-throughput imaging to ask whether the location within the nucleus affects interaction frequency. We find strong enrichment of many interactions at specific radial positions. Position-dependency of interactions was cell-type specific, correlated with local chromatin type, and cell-type-specific enriched associations were marked by increased variability, sometimes without a significant decrease in mean spatial distance. These observations demonstrate that the folding of the chromatin fiber, which brings genomically distant loci into proximity, and the position of that chromatin fiber relative to nuclear landmarks, are closely linked.
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Affiliation(s)
- Elizabeth H. Finn
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, United States of America
| | - Tom Misteli
- National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
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11
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Efficient DNA fluorescence labeling via base excision trapping. Nat Commun 2022; 13:5043. [PMID: 36028479 PMCID: PMC9418136 DOI: 10.1038/s41467-022-32494-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 08/03/2022] [Indexed: 01/19/2023] Open
Abstract
Fluorescence labeling of DNAs is broadly useful, but methods for labeling are expensive and labor-intensive. Here we describe a general method for fluorescence labeling of oligonucleotides readily and cost-efficiently via base excision trapping (BETr), employing deaminated DNA bases to mark label positions, which are excised by base excision repair enzymes generating AP sites. Specially designed aminooxy-substituted rotor dyes trap the AP sites, yielding high emission intensities. BETr is orthogonal to DNA synthesis by polymerases, enabling multi-uracil incorporation into an amplicon and in situ BETr labeling without washing. BETr also enables labeling of dsDNA such as genomic DNA at a high labeling density in a single tube by use of nick translation. Use of two different deaminated bases facilitates two-color site-specific labeling. Use of a multi-labeled DNA construct as a bright fluorescence tag is demonstrated through the conjugation to an antibody for imaging proteins. Finally, double-strand selectivity of a repair enzyme is harnessed in sensitive reporting on the presence of a target DNA or RNA in a mixture with isothermal turnover and single nucleotide specificity. Overall, the results document a convenient and versatile method for general fluorescence labeling of DNAs.
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