1
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Mondal AK, Gaur M, Advani J, Swaroop A. Epigenome-metabolism nexus in the retina: implications for aging and disease. Trends Genet 2024; 40:718-729. [PMID: 38782642 PMCID: PMC11303112 DOI: 10.1016/j.tig.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/25/2024]
Abstract
Intimate links between epigenome modifications and metabolites allude to a crucial role of cellular metabolism in transcriptional regulation. Retina, being a highly metabolic tissue, adapts by integrating inputs from genetic, epigenetic, and extracellular signals. Precise global epigenomic signatures guide development and homeostasis of the intricate retinal structure and function. Epigenomic and metabolic realignment are hallmarks of aging and highlight a link of the epigenome-metabolism nexus with aging-associated multifactorial traits affecting the retina, including age-related macular degeneration and glaucoma. Here, we focus on emerging principles of epigenomic and metabolic control of retinal gene regulation, with emphasis on their contribution to human disease. In addition, we discuss potential mitigation strategies involving lifestyle changes that target the epigenome-metabolome relationship for maintaining retinal function.
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Affiliation(s)
- Anupam K Mondal
- Neurobiology, Neurodegeneration, and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mohita Gaur
- Neurobiology, Neurodegeneration, and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jayshree Advani
- Neurobiology, Neurodegeneration, and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology, Neurodegeneration, and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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2
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De Ridder K, Che H, Leroy K, Thienpont B. Benchmarking of methods for DNA methylome deconvolution. Nat Commun 2024; 15:4134. [PMID: 38755121 PMCID: PMC11099101 DOI: 10.1038/s41467-024-48466-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 04/30/2024] [Indexed: 05/18/2024] Open
Abstract
Defining the number and abundance of different cell types in tissues is important for understanding disease mechanisms as well as for diagnostic and prognostic purposes. Typically, this is achieved by immunohistological analyses, cell sorting, or single-cell RNA-sequencing. Alternatively, cell-specific DNA methylome information can be leveraged to deconvolve cell fractions from a bulk DNA mixture. However, comprehensive benchmarking of deconvolution methods and modalities was not yet performed. Here we evaluate 16 deconvolution algorithms, developed either specifically for DNA methylome data or more generically. We assess the performance of these algorithms, and the effect of normalization methods, while modeling variables that impact deconvolution performance, including cell abundance, cell type similarity, reference panel size, method for methylome profiling (array or sequencing), and technical variation. We observe differences in algorithm performance depending on each these variables, emphasizing the need for tailoring deconvolution analyses. The complexity of the reference, marker selection method, number of marker loci and, for sequencing-based assays, sequencing depth have a marked influence on performance. By developing handles to select the optimal analysis configuration, we provide a valuable source of information for studies aiming to deconvolve array- or sequencing-based methylation data.
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Affiliation(s)
- Kobe De Ridder
- Laboratory for Functional Epigenetics, Department of Human Genetics, KU Leuven, 3000, Leuven, Belgium
| | - Huiwen Che
- Laboratory for Functional Epigenetics, Department of Human Genetics, KU Leuven, 3000, Leuven, Belgium
| | - Kaat Leroy
- Laboratory for Functional Epigenetics, Department of Human Genetics, KU Leuven, 3000, Leuven, Belgium
| | - Bernard Thienpont
- Laboratory for Functional Epigenetics, Department of Human Genetics, KU Leuven, 3000, Leuven, Belgium.
- KU Leuven Institute for Single Cell Omics (LISCO), KU Leuven, 3000, Leuven, Belgium.
- KU Leuven Cancer Institute (LKI), KU Leuven, 3000, Leuven, Belgium.
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3
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Rajanala K, Upadhyay A. Epigenetic Switches in Retinal Homeostasis and Target for Drug Development. Int J Mol Sci 2024; 25:2840. [PMID: 38474086 DOI: 10.3390/ijms25052840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Retinal homeostasis, a tightly regulated process maintaining the functional integrity of the retina, is vital for visual function. Emerging research has unveiled the critical role of epigenetic regulation in controlling gene expression patterns during retinal development, maintenance, and response to mutational loads and injuries. Epigenetic switches, including DNA methylation, histone modifications, and non-coding RNAs, play pivotal roles in orchestrating retinal gene expression and cellular responses through various intracellular, extracellular, and environmental modulators. This review compiles the current knowledge on epigenetic switches in retinal homeostasis, providing a deeper understanding of their impact on retinal structural integrity and function and using them as potential targets for therapeutic interventions.
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Affiliation(s)
| | - Arun Upadhyay
- Ocugen Inc., 11 Great Valley Parkway, Malvern, PA 19355, USA
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4
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Lu CF, Zhou YN, Zhang J, Su S, Liu Y, Peng GH, Zang W, Cao J. The role of epigenetic methylation/demethylation in the regulation of retinal photoreceptors. Front Cell Dev Biol 2023; 11:1149132. [PMID: 37305686 PMCID: PMC10251769 DOI: 10.3389/fcell.2023.1149132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 05/09/2023] [Indexed: 06/13/2023] Open
Abstract
Photoreceptors are integral and crucial for the retina, as they convert light into electrical signals. Epigenetics plays a vital role in determining the precise expression of genetic information in space and time during the development and maturation of photoreceptors, cell differentiation, degeneration, death, and various pathological processes. Epigenetic regulation has three main manifestations: histone modification, DNA methylation, and RNA-based mechanisms, where methylation is involved in two regulatory mechanisms-histone methylation and DNA methylation. DNA methylation is the most studied form of epigenetic modification, while histone methylation is a relatively stable regulatory mechanism. Evidence suggests that normal methylation regulation is essential for the growth and development of photoreceptors and the maintenance of their functions, while abnormal methylation can lead to many pathological forms of photoreceptors. However, the role of methylation/demethylation in regulating retinal photoreceptors remains unclear. Therefore, this study aims to review the role of methylation/demethylation in regulating photoreceptors in various physiological and pathological situations and discuss the underlying mechanisms involved. Given the critical role of epigenetic regulation in gene expression and cellular differentiation, investigating the specific molecular mechanisms underlying these processes in photoreceptors may provide valuable insights into the pathogenesis of retinal diseases. Moreover, understanding these mechanisms could lead to the development of novel therapies that target the epigenetic machinery, thereby promoting the maintenance of retinal function throughout an individual's lifespan.
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Affiliation(s)
- Chao-Fan Lu
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Ya-Nan Zhou
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jingjing Zhang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Songxue Su
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Yupeng Liu
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Guang-Hua Peng
- Department of Pathophysiology, Basic Medical College, Zhengzhou University, Zhengzhou, China
- Laboratory of Visual Cell Differentiation and Regulation, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Weidong Zang
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
| | - Jing Cao
- Department of Anatomy, Basic Medical College, Zhengzhou University, Zhengzhou, China
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5
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Starr CR, Gorbatyuk MS. Posttranslational modifications of proteins in diseased retina. Front Cell Neurosci 2023; 17:1150220. [PMID: 37066080 PMCID: PMC10097899 DOI: 10.3389/fncel.2023.1150220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 03/13/2023] [Indexed: 04/03/2023] Open
Abstract
Posttranslational modifications (PTMs) are known to constitute a key step in protein biosynthesis and in the regulation of protein functions. Recent breakthroughs in protein purification strategies and current proteome technologies make it possible to identify the proteomics of healthy and diseased retinas. Despite these advantages, the research field identifying sets of posttranslationally modified proteins (PTMomes) related to diseased retinas is significantly lagging, despite knowledge of the major retina PTMome being critical to drug development. In this review, we highlight current updates regarding the PTMomes in three retinal degenerative diseases-namely, diabetic retinopathy (DR), glaucoma, and retinitis pigmentosa (RP). A literature search reveals the necessity to expedite investigations into essential PTMomes in the diseased retina and validate their physiological roles. This knowledge would accelerate the development of treatments for retinal degenerative disorders and the prevention of blindness in affected populations.
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Affiliation(s)
| | - Marina S. Gorbatyuk
- Department of Optometry and Vision Science, University of Alabama at Birmingham, Birmingham, AL, United States
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6
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Kuzelova A, Dupacova N, Antosova B, Sunny SS, Kozmik Z, Paces J, Skoultchi AI, Stopka T, Kozmik Z. Chromatin Remodeling Enzyme Snf2h Is Essential for Retinal Cell Proliferation and Photoreceptor Maintenance. Cells 2023; 12:1035. [PMID: 37048108 PMCID: PMC10093269 DOI: 10.3390/cells12071035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 03/31/2023] Open
Abstract
Chromatin remodeling complexes are required for many distinct nuclear processes such as transcription, DNA replication, and DNA repair. However, the contribution of these complexes to the development of complex tissues within an organism is poorly characterized. Imitation switch (ISWI) proteins are among the most evolutionarily conserved ATP-dependent chromatin remodeling factors and are represented by yeast Isw1/Isw2, and their vertebrate counterparts Snf2h (Smarca5) and Snf2l (Smarca1). In this study, we focused on the role of the Snf2h gene during the development of the mammalian retina. We show that Snf2h is expressed in both retinal progenitors and post-mitotic retinal cells. Using Snf2h conditional knockout mice (Snf2h cKO), we found that when Snf2h is deleted, the laminar structure of the adult retina is not retained, the overall thickness of the retina is significantly reduced compared with controls, and the outer nuclear layer (ONL) is completely missing. The depletion of Snf2h did not influence the ability of retinal progenitors to generate all the differentiated retinal cell types. Instead, the Snf2h function is critical for the proliferation of retinal progenitor cells. Cells lacking Snf2h have a defective S-phase, leading to the entire cell division process impairments. Although all retinal cell types appear to be specified in the absence of the Snf2h function, cell-cycle defects and concomitantly increased apoptosis in Snf2h cKO result in abnormal retina lamination, complete destruction of the photoreceptor layer, and consequently, a physiologically non-functional retina.
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Affiliation(s)
- Andrea Kuzelova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Naoko Dupacova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Barbora Antosova
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Sweetu Susan Sunny
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
| | - Zbynek Kozmik
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Jan Paces
- Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague, Czech Republic
| | - Arthur I. Skoultchi
- Department of Cell Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, NY 10461, USA
| | - Tomas Stopka
- Biocev, First Faculty of Medicine, Charles University, Prumyslova 595, 252 50 Vestec, Czech Republic
| | - Zbynek Kozmik
- Laboratory of Transcriptional Regulation, Institute of Molecular Genetics of the Czech Academy of Sciences, 142 20 Prague, Czech Republic
- Research Unit for Rare Diseases, Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital in Prague, 128 08 Prague, Czech Republic
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7
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Kuzelova A, Dupacova N, Antosova B, Sunny SS, Kozmik Z, Paces J, Skoultchi AI, Stopka T, Kozmik Z. Chromatin remodeling enzyme Snf2h is essential for retinal cell proliferation and photoreceptor maintenance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.13.528323. [PMID: 36824843 PMCID: PMC9948993 DOI: 10.1101/2023.02.13.528323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Chromatin remodeling complexes are required for many distinct nuclear processes such as transcription, DNA replication and DNA repair. However, how these complexes contribute to the development of complex tissues within an organism is poorly characterized. Imitation switch (ISWI) proteins are among the most evolutionarily conserved ATP-dependent chromatin remodeling factors and are represented by yeast Isw1/Isw2, and their vertebrate counterparts Snf2h (Smarca5) and Snf2l (Smarca1). In this study, we focused on the role of the Snf2h gene during development of the mammalian retina. We show that Snf2h is expressed in both retinal progenitors and post-mitotic retinal cells. Using Snf2h conditional knockout mice ( Snf2h cKO), we found that when Snf2h is deleted the laminar structure of the adult retina is not retained, the overall thickness of the retina is significantly reduced compared with controls, and the outer nuclear layer (ONL) is completely missing. Depletion of Snf2h did not influence the ability of retinal progenitors to generate all of the differentiated retinal cell types. Instead, Snf2h function is critical for proliferation of retinal progenitor cells. Cells lacking Snf2h have a defective S-phase, leading to the entire cell division process impairments. Although, all retinal cell types appear to be specified in the absence of Snf2h function, cell cycle defects and concomitantly increased apoptosis in Snf2h cKO result in abnormal retina lamination, complete destruction of the photoreceptor layer and, consequently, in a physiologically non-functional retina.
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8
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Moore SM, Christoforidis JB. Advances in Ophthalmic Epigenetics and Implications for Epigenetic Therapies: A Review. Genes (Basel) 2023; 14:417. [PMID: 36833344 PMCID: PMC9957018 DOI: 10.3390/genes14020417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/02/2023] [Accepted: 02/03/2023] [Indexed: 02/08/2023] Open
Abstract
The epigenome represents a vast molecular apparatus that writes, reads, and erases chemical modifications to the DNA and histone code without changing the DNA base-pair sequence itself. Recent advances in molecular sequencing technology have revealed that epigenetic chromatin marks directly mediate critical events in retinal development, aging, and degeneration. Epigenetic signaling regulates retinal progenitor (RPC) cell cycle exit during retinal laminar development, giving rise to retinal ganglion cells (RGCs), amacrine cells, horizontal cells, bipolar cells, photoreceptors, and Müller glia. Age-related epigenetic changes such as DNA methylation in the retina and optic nerve are accelerated in pathogenic conditions such as glaucoma and macular degeneration, but reversing these epigenetic marks may represent a novel therapeutic target. Epigenetic writers also integrate environmental signals such as hypoxia, inflammation, and hyperglycemia in complex retinal conditions such as diabetic retinopathy (DR) and choroidal neovascularization (CNV). Histone deacetylase (HDAC) inhibitors protect against apoptosis and photoreceptor degeneration in animal models of retinitis pigmentosa (RP). The epigenome represents an intriguing therapeutic target for age-, genetic-, and neovascular-related retinal diseases, though more work is needed before advancement to clinical trials.
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Affiliation(s)
- Spencer M. Moore
- Department of Ophthalmology & Vision Science, University of Arizona College of Medicine-Tucson, Tucson, AZ 85711, USA
| | - John B. Christoforidis
- Department of Ophthalmology & Vision Science, University of Arizona College of Medicine-Tucson, Tucson, AZ 85711, USA
- Retina Specialists of Southern Arizonam, Tucson, AZ 85712, USA
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9
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Cai C, Meng C, He S, Gu C, Lhamo T, Draga D, Luo D, Qiu Q. DNA methylation in diabetic retinopathy: pathogenetic role and potential therapeutic targets. Cell Biosci 2022; 12:186. [DOI: 10.1186/s13578-022-00927-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022] Open
Abstract
Abstract
Background
Diabetic retinopathy (DR), a specific neuron-vascular complication of diabetes, is a major cause of vision loss among middle-aged people worldwide, and the number of DR patients will increase with the increasing incidence of diabetes. At present, it is limited in difficult detection in the early stages, limited treatment and unsatisfactory treatment effects in the advanced stages.
Main body
The pathogenesis of DR is complicated and involves epigenetic modifications, oxidative stress, inflammation and neovascularization. These factors influence each other and jointly promote the development of DR. DNA methylation is the most studied epigenetic modification, which has been a key role in the regulation of gene expression and the occurrence and development of DR. Thus, this review investigates the relationship between DNA methylation and other complex pathological processes in the development of DR. From the perspective of DNA methylation, this review provides basic insights into potential biomarkers for diagnosis, preventable risk factors, and novel targets for treatment.
Conclusion
DNA methylation plays an indispensable role in DR and may serve as a prospective biomarker of this blinding disease in its relatively early stages. In combination with inhibitors of DNA methyltransferases can be a potential approach to delay or even prevent patients from getting advanced stages of DR.
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10
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Wang X, Sarver AL, Han Q, Seiler CL, Xie C, Lu H, Forster CL, Tretyakova NY, Hallstrom TC. UHRF2 regulates cell cycle, epigenetics and gene expression to control the timing of retinal progenitor and ganglion cell differentiation. Development 2022; 149:274710. [PMID: 35285483 PMCID: PMC8984156 DOI: 10.1242/dev.195644] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 01/28/2022] [Indexed: 11/20/2022]
Abstract
Ubiquitin-like, containing PHD and RING finger domains 2 (UHRF2) regulates cell cycle and binds 5-hydroxymethylcytosine (5hmC) to promote completion of DNA demethylation. Uhrf2-/- mice are without gross phenotypic defects; however, the cell cycle and epigenetic regulatory functions of Uhrf2 during retinal tissue development are unclear. Retinal progenitor cells (RPCs) produce all retinal neurons and Müller glia in a predictable sequence controlled by the complex interplay between extrinsic signaling, cell cycle, epigenetic changes and cell-specific transcription factor activation. In this study, we find that UHRF2 accumulates in RPCs, and its conditional deletion from mouse RPCs reduced 5hmC, altered gene expressions and disrupted retinal cell proliferation and differentiation. Retinal ganglion cells were overproduced in Uhrf2-deficient retinae at the expense of VSX2+ RPCs. Most other cell types were transiently delayed in differentiation. Expression of each member of the Tet3/Uhrf2/Tdg active demethylation pathway was reduced in Uhrf2-deficient retinae, consistent with locally reduced 5hmC in their gene bodies. This study highlights a novel role of UHRF2 in controlling the transition from RPCs to differentiated cell by regulating cell cycle, epigenetic and gene expression decisions.
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Affiliation(s)
- Xiaohong Wang
- Department of Pediatrics, Division of Blood and Marrow Transplantation, 420 Delaware Street S.E., University of Minnesota, Minneapolis, MN 55455, USA
| | - Aaron L Sarver
- Institute for Health Informatics, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Qiyuan Han
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Christopher L Seiler
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Chencheng Xie
- Department of Pediatrics, Division of Blood and Marrow Transplantation, 420 Delaware Street S.E., University of Minnesota, Minneapolis, MN 55455, USA
| | - Huarui Lu
- Department of Pediatrics, Division of Blood and Marrow Transplantation, 420 Delaware Street S.E., University of Minnesota, Minneapolis, MN 55455, USA
| | - Colleen L Forster
- BioNet, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | - Timothy C Hallstrom
- Department of Pediatrics, Division of Blood and Marrow Transplantation, 420 Delaware Street S.E., University of Minnesota, Minneapolis, MN 55455, USA
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11
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Dvoriantchikova G, Lypka KR, Ivanov D. The Potential Role of Epigenetic Mechanisms in the Development of Retinitis Pigmentosa and Related Photoreceptor Dystrophies. Front Genet 2022; 13:827274. [PMID: 35360866 PMCID: PMC8961674 DOI: 10.3389/fgene.2022.827274] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/25/2022] [Indexed: 12/13/2022] Open
Abstract
Retinitis pigmentosa and related photoreceptor dystrophies (RPRPD) are rare retinal diseases caused by hereditary gene mutations resulting in photoreceptor death, followed by vision loss. While numerous genes involved in these diseases have been identified, many cases have still not been associated with any gene, indicating that new mechanisms may be involved in the pathogenesis of these photoreceptor dystrophies. Many genes associated with RPRPD regulate photoreceptor specification and maturation in the developing retina. Since retinal development begins with a population of equivalent, proliferating retinal progenitor cells (RPCs) having a specific “competence” in generating all types of retinal neurons, including cone and rod photoreceptors, we tested the epigenetic changes in promoters of genes required for photoreceptor development and genes associated with RPRPD during RPC differentiation into cone and rod photoreceptors. We found that promoters of many of these genes are epigenetically repressed in RPCs but have no epigenetic restrictions in photoreceptors. Our findings also suggest that DNA methylation as an epigenetic mark, and DNA demethylation as a process, are more important than other epigenetic marks or mechanisms in the pathogenesis of these diseases. Most notably, irregularities in the DNA demethylation process during the RPC-to-photoreceptor transition may significantly contribute to retinitis pigmentosa (RP) pathogenesis since genes with hypermethylated promoters in RPCs account for at least 40% of autosomal recessive RP cases and at least 30% of autosomal dominant RP cases. Thus, we proposed an epigenetic model according to which unsuccessful demethylation of regulatory sequences (e.g., promoters, enhancers) of genes required for photoreceptor development, maturation, and function during the RPC-to-photoreceptor transition may reduce or even eliminate their activity, leading to RPRPD without any inheritable mutations in these genes.
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Affiliation(s)
- Galina Dvoriantchikova
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Karin Rose Lypka
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Dmitry Ivanov
- Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, United States
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, FL, United States
- *Correspondence: Dmitry Ivanov,
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12
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Song J, VanBuskirk JA, Merbs SL. Regulation of Opsin Gene Expression by DNA Methylation and Histone Acetylation. Int J Mol Sci 2022; 23:ijms23031408. [PMID: 35163334 PMCID: PMC8836077 DOI: 10.3390/ijms23031408] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/22/2022] [Accepted: 01/23/2022] [Indexed: 02/04/2023] Open
Abstract
One important role of epigenetic regulation is controlling gene expression in development and homeostasis. However, little is known about epigenetics' role in regulating opsin expression. Cell cultures (HEK 293, Y79, and WERI) producing different levels of opsins were treated with 5-aza-2'-deoxycytidine (5-Aza-dc) and/or sodium butyrate (SB) or suberoylanilide hydroxamic acid (SAHA) for 72 h. Global DNA methylation, site-specific methylation, and expressions of opsins were measured by LUMA assay, bisulfite pyrosequencing, and qPCR, respectively. Mouse retinal explants from wild-type P0/P1 pups were ex vivo cultured with/without 5-Aza-dc or SAHA for 6 days. The morphology of explants, DNA methylation, and expressions of opsins was examined. The drugs induced global DNA hypomethylation or increased histone acetylation in cells, including DNA hypomethylation of rhodopsin (RHO) and L-opsin (OPN1LW) and a concomitant increase in their expression. Further upregulation of RHO and/or OPN1LW in HEK 293 or WERI cells was observed with 5-Aza-dc and either SB or SAHA combination treatment. Mouse retinal explants developed normally but had drug-dependent differential DNA methylation and expression patterns of opsins. DNA methylation and histone acetylation directly regulate opsin expression both in vitro and ex vivo. The ability to manipulate opsin expression using epigenetic modifiers enables further study into the role of epigenetics in eye development and disease.
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Affiliation(s)
- Jin Song
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Correspondence: (J.S.); (S.L.M.)
| | - Julia A. VanBuskirk
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA;
| | - Shannath L. Merbs
- Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, MD 21287, USA
- Correspondence: (J.S.); (S.L.M.)
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13
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Wu J, Liu LL, Cao M, Hu A, Hu D, Luo Y, Wang H, Zhong JN. DNA methylation plays important roles in retinal development and diseases. Exp Eye Res 2021; 211:108733. [PMID: 34418429 DOI: 10.1016/j.exer.2021.108733] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 08/16/2021] [Accepted: 08/17/2021] [Indexed: 12/16/2022]
Abstract
DNA methylation is important in developing and post-mitotic cells in various tissues. Recent studies have shown that DNA methylation is highly dynamic, and plays important roles during retinal development and aging. In addition, the dynamic regulation of DNA methylation is involved in the occurrence and development of age-related macular degeneration and diabetic retinopathy and shows potential in disease diagnoses and prognoses. This review introduces the epigenetic concepts of DNA methylation and demethylation with an emphasis on their regulatory roles in retinal development and related diseases. Moreover, we propose exciting ideas such as its crosstalk with other epigenetic modifications and retinal regeneration, to provide a potential direction for understanding retinal diseases from the epigenetic perspective.
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Affiliation(s)
- Jing Wu
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China; Department of Ophthalmology, Lishui Municipal Central Hospital, Lishui, 323000, Zhejiang Province, China
| | - Lin-Lin Liu
- Department of Ophthalmology, The First Affiliated Hospital of Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China
| | - Miao Cao
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China; Department of Ophthalmology, The First Affiliated Hospital of Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China
| | - Ang Hu
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China
| | - Die Hu
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China; Department of Ophthalmology, The First Affiliated Hospital of Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China
| | - Yan Luo
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China
| | - Hui Wang
- Department of Ophthalmology, The First Affiliated Hospital of Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China.
| | - Jia-Ning Zhong
- Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases of Ministry of Education, Gannan Medical University, Ganzhou, 341000, Jiangxi Province, China.
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14
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Raeisossadati R, Ferrari MFR, Kihara AH, AlDiri I, Gross JM. Epigenetic regulation of retinal development. Epigenetics Chromatin 2021; 14:11. [PMID: 33563331 PMCID: PMC7871400 DOI: 10.1186/s13072-021-00384-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/28/2021] [Indexed: 01/10/2023] Open
Abstract
In the developing vertebrate retina, retinal progenitor cells (RPCs) proliferate and give rise to terminally differentiated neurons with exquisite spatio-temporal precision. Lineage commitment, fate determination and terminal differentiation are controlled by intricate crosstalk between the genome and epigenome. Indeed, epigenetic regulation plays pivotal roles in numerous cell fate specification and differentiation events in the retina. Moreover, aberrant chromatin structure can contribute to developmental disorders and retinal pathologies. In this review, we highlight recent advances in our understanding of epigenetic regulation in the retina. We also provide insight into several aspects of epigenetic-related regulation that should be investigated in future studies of retinal development and disease. Importantly, focusing on these mechanisms could contribute to the development of novel treatment strategies targeting a variety of retinal disorders.
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Affiliation(s)
- Reza Raeisossadati
- Departamento de Genética E Biologia Evolutiva, Instituto de Biociencias, Universidade de Sao Paulo, Rua Do Matao, 277, Cidade Universitaria, Sao Paulo, SP, 05508-090, Brazil.,Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Merari F R Ferrari
- Departamento de Genética E Biologia Evolutiva, Instituto de Biociencias, Universidade de Sao Paulo, Rua Do Matao, 277, Cidade Universitaria, Sao Paulo, SP, 05508-090, Brazil
| | | | - Issam AlDiri
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jeffrey M Gross
- Departments of Ophthalmology and Developmental Biology, Louis J. Fox Center for Vision Restoration, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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15
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Atilano SR, Kenney MC, Briscoe AD, Jameson KA. A two-step method for identifying photopigment opsin and rhodopsin gene sequences underlying human color vision phenotypes. Mol Vis 2020; 26:158-172. [PMID: 32180681 PMCID: PMC7058431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 03/03/2020] [Indexed: 11/02/2022] Open
Abstract
Purpose To present a detailed, reliable long range-PCR and sequencing (LR-PCR-Seq) procedure to identify human opsin gene sequences for variations in the long wavelength-sensitive (OPN1LW), medium wavelength-sensitive (OPN1MW), short wavelength-sensitive (OPN1SW), and rhodopsin (RHO) genes. Methods Color vision was assessed for nine subjects using the Farnsworth-Munsell 100 hue test, Ishihara pseudoisochromatic plates, and the Rabin cone-contrast threshold procedure (ColorDX, Konan Medical). The color vision phenotypes were normal trichromacy (n = 3), potential tetrachromacy (n = 3), dichromacy (n = 2), and unexplained low color vision (n = 1). DNA was isolated from blood or saliva and LR-PCR amplified into individual products: OPN1LW (4,045 bp), OPN1MW (4,045 bp), OPN1SW (3,326 bp), and RHO (6,715 bp). Each product was sequenced using specific internal primer sets. Analysis was performed with Mutation Surveyor software. Results The LR-PCR-Seq technique identified known single nucleotide polymorphisms (SNPs) in OPN1LW and OPN1MW gene codons (180, 230, 233, 277, and 285), as well as those for lesser studied codons (174, 178, 236, 274, 279, 298 and 309) in the OPN1LW and OPN1MW genes. Additionally, six SNP variants in the OPN1MW and OPN1LW genes not previously reported in the NCBI dbSNP database were identified. An unreported poly-T region within intron 5(c.36+126) of the rhodopsin gene was also found, and analysis showed it to be highly conserved in mammalian species. Conclusions This LR-PCR-Seq procedure (single PCR reaction per gene followed by sequencing) can identify exonic and intronic SNP variants in OPN1LW, OPN1MW, OPN1SW, and rhodopsin genes. There is no need for restriction enzyme digestion or multiple PCR steps that can introduce errors. Future studies will combine the LR-PCR-Seq with perceptual behavior measures, allowing for accurate correlations between opsin genotypes, retinal photopigment phenotypes, and color perception behaviors.
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Affiliation(s)
- Shari R. Atilano
- Gavin Herbert Eye Institute, School of Medicine, University of California, Irvine, CA
| | - M. Cristina Kenney
- Gavin Herbert Eye Institute, School of Medicine, University of California, Irvine, CA,Department of Pathology and Laboratory Medicine, University of California Irvine, Irvine, CA
| | - Adriana D. Briscoe
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA
| | - Kimberly A. Jameson
- Institute for Mathematical Behavioral Sciences, University of California Irvine, Irvine, CA
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16
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Magnuson JT, Bautista NM, Lucero J, Lund AK, Xu EG, Schlenk D, Burggren WW, Roberts AP. Exposure to Crude Oil Induces Retinal Apoptosis and Impairs Visual Function in Fish. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:2843-2850. [PMID: 32036658 DOI: 10.1021/acs.est.9b07658] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) present in crude oil are known to impair visual development in fish. However, the underlying mechanism of PAH-induced toxicity to the visual system of fish is not understood. Embryonic zebrafish (Danio rerio) at 4 h post fertilization were exposed to weathered crude oil and assessed for visual function using an optokinetic response, with subsequent samples taken for immunohistochemistry and gene expression analysis. Cardiotoxicity was also assessed by measuring the heart rate, stroke volume, and cardiac output, as cardiac performance has been proposed to be a contributing factor to eye-associated malformations following oil exposure. Larvae exposed to the highest concentrations of crude oil (89.8 μg/L) exhibited an increased occurrence of bradycardia, though no changes in stroke volume or cardiac output were observed. However, genes important in eye development and phototransduction were downregulated in oil-exposed larvae, with an increased occurrence of cellular apoptosis, reduced neuronal connection, and reduced optokinetic behavioral response in zebrafish larvae.
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Affiliation(s)
- Jason T Magnuson
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
| | - Naim M Bautista
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
| | - JoAnn Lucero
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
| | - Amie K Lund
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
| | - Elvis Genbo Xu
- Department of Chemical Engineering, McGill University, Montreal, Quebec H3A0C5, Canada
| | - Daniel Schlenk
- Department of Environmental Sciences, University of California, Riverside, Riverside, California 92521, United States
| | - Warren W Burggren
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
| | - Aaron P Roberts
- Department of Biological Sciences and Advanced Environmental Research Institute, University of North Texas, Denton, Texas 76203, United States
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17
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Seritrakul P, Gross JM. Genetic and epigenetic control of retinal development in zebrafish. Curr Opin Neurobiol 2019; 59:120-127. [PMID: 31255843 PMCID: PMC6888853 DOI: 10.1016/j.conb.2019.05.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/23/2019] [Accepted: 05/28/2019] [Indexed: 12/24/2022]
Abstract
The vertebrate retina is a complex structure composed of seven cell types (six neuron and one glia), and all of which originate from a seemingly homogeneous population of proliferative multipotent retinal progenitor cells (RPCs) that exit the cell cycle and differentiate in a spatio-temporally regulated and stereotyped fashion. This neurogenesis process requires intricate genetic regulation involving a combination of cell intrinsic transcription factors and extrinsic signaling molecules, and many critical factors have been identified that influence the timing and composition of the developing retina. Adding complexity to the process, over the past decade, a variety of epigenetic regulatory mechanisms have been shown to influence neurogenesis, and these include changes in histone modifications and the chromatin landscape and changes in DNA methylation and hydroxymethylation patterns. This review summarizes recent findings in the genetic and epigenetic regulation of retinal development, with an emphasis on the zebrafish model system, and it outlines future areas of investigation that will continue to push the field forward into the epigenomics era.
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Affiliation(s)
- Pawat Seritrakul
- Faculty of Animal Sciences and Agricultural Technology, Silpakorn University, Phetchaburi, 76120, Thailand.
| | - Jeffrey M Gross
- Departments of Ophthalmology, and Developmental Biology, The Louis J. Fox Center for Vision Restoration, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, United States.
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18
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Blond F, Léveillard T. Functional Genomics of the Retina to Elucidate its Construction and Deconstruction. Int J Mol Sci 2019; 20:E4922. [PMID: 31590277 PMCID: PMC6801968 DOI: 10.3390/ijms20194922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/01/2019] [Indexed: 12/20/2022] Open
Abstract
The retina is the light sensitive part of the eye and nervous tissue that have been used extensively to characterize the function of the central nervous system. The retina has a central position both in fundamental biology and in the physiopathology of neurodegenerative diseases. We address the contribution of functional genomics to the understanding of retinal biology by reviewing key events in their historical perspective as an introduction to major findings that were obtained through the study of the retina using genomics, transcriptomics and proteomics. We illustrate our purpose by showing that most of the genes of interest for retinal development and those involved in inherited retinal degenerations have a restricted expression to the retina and most particularly to photoreceptors cells. We show that the exponential growth of data generated by functional genomics is a future challenge not only in terms of storage but also in terms of accessibility to the scientific community of retinal biologists in the future. Finally, we emphasize on novel perspectives that emerge from the development of redox-proteomics, the new frontier in retinal biology.
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Affiliation(s)
- Frédéric Blond
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
| | - Thierry Léveillard
- Department of Genetics, Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, F-75012 Paris, France.
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19
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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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20
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Corso-Díaz X, Jaeger C, Chaitankar V, Swaroop A. Epigenetic control of gene regulation during development and disease: A view from the retina. Prog Retin Eye Res 2018; 65:1-27. [PMID: 29544768 PMCID: PMC6054546 DOI: 10.1016/j.preteyeres.2018.03.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 02/01/2018] [Accepted: 03/08/2018] [Indexed: 12/20/2022]
Abstract
Complex biological processes, such as organogenesis and homeostasis, are stringently regulated by genetic programs that are fine-tuned by epigenetic factors to establish cell fates and/or to respond to the microenvironment. Gene regulatory networks that guide cell differentiation and function are modulated and stabilized by modifications to DNA, RNA and proteins. In this review, we focus on two key epigenetic changes - DNA methylation and histone modifications - and discuss their contribution to retinal development, aging and disease, especially in the context of age-related macular degeneration (AMD) and diabetic retinopathy. We highlight less-studied roles of DNA methylation and provide the RNA expression profiles of epigenetic enzymes in human and mouse retina in comparison to other tissues. We also review computational tools and emergent technologies to profile, analyze and integrate epigenetic information. We suggest implementation of editing tools and single-cell technologies to trace and perturb the epigenome for delineating its role in transcriptional regulation. Finally, we present our thoughts on exciting avenues for exploring epigenome in retinal metabolism, disease modeling, and regeneration.
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Affiliation(s)
- Ximena Corso-Díaz
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Catherine Jaeger
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Vijender Chaitankar
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Anand Swaroop
- Neurobiology-Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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21
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Hossain RA, Dunham NR, Enke RA, Berndsen CE. In silico modeling of epigenetic-induced changes in photoreceptor cis-regulatory elements. Mol Vis 2018; 24:218-230. [PMID: 29563767 PMCID: PMC5851326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 03/12/2018] [Indexed: 10/30/2022] Open
Abstract
Purpose DNA methylation is a well-characterized epigenetic repressor of mRNA transcription in many plant and vertebrate systems. However, the mechanism of this repression is not fully understood. The process of transcription is controlled by proteins that regulate recruitment and activity of RNA polymerase by binding to specific cis-regulatory sequences. Cone-rod homeobox (CRX) is a well-characterized mammalian transcription factor that controls photoreceptor cell-specific gene expression. Although much is known about the functions and DNA binding specificity of CRX, little is known about how DNA methylation modulates CRX binding affinity to genomic cis-regulatory elements. Methods We used bisulfite pyrosequencing of human ocular tissues to measure DNA methylation levels of the regulatory regions of RHO, PDE6B, PAX6, and LINE1 retrotransposon repeats. To describe the molecular mechanism of repression, we used molecular modeling to illustrate the effect of DNA methylation on human RHO regulatory sequences. Results In this study, we demonstrate an inverse correlation between DNA methylation in regulatory regions adjacent to the human RHO and PDE6B genes and their subsequent transcription in human ocular tissues. Docking of CRX to the DNA models shows that CRX interacts with the grooves of these sequences, suggesting changes in groove structure could regulate binding. Molecular dynamics simulations of the RHO promoter and enhancer regions show changes in the flexibility and groove width upon epigenetic modification. Models also demonstrate changes in the local dynamics of CRX binding sites within RHO regulatory sequences which may account for the repression of CRX-dependent transcription. Conclusions Collectively, these data demonstrate epigenetic regulation of CRX binding sites in human retinal tissue and provide insight into the mechanism of this mode of epigenetic regulation to be tested in future experiments.
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Affiliation(s)
- Reafa A. Hossain
- Department of Biology, James Madison University, Harrisonburg, VA
| | | | - Raymond A. Enke
- Department of Biology, James Madison University, Harrisonburg, VA
- Center for Genome and Metagenome Studies, James Madison University, Harrisonburg, VA
| | - Christopher E. Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA
- Center for Genome and Metagenome Studies, James Madison University, Harrisonburg, VA
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22
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Berdasco M, Gómez A, Rubio MJ, Català-Mora J, Zanón-Moreno V, Lopez M, Hernández C, Yoshida S, Nakama T, Ishikawa K, Ishibashi T, Boubekeur AM, Louhibi L, Pujana MA, Sayols S, Setien F, Corella D, de Torres C, Parareda A, Mora J, Zhao L, Zhang K, Lleonart ME, Alonso J, Simó R, Caminal JM, Esteller M. DNA Methylomes Reveal Biological Networks Involved in Human Eye Development, Functions and Associated Disorders. Sci Rep 2017; 7:11762. [PMID: 28924151 PMCID: PMC5603607 DOI: 10.1038/s41598-017-12084-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 09/04/2017] [Indexed: 01/07/2023] Open
Abstract
This work provides a comprehensive CpG methylation landscape of the different layers of the human eye that unveils the gene networks associated with their biological functions and how these are disrupted in common visual disorders. Herein, we firstly determined the role of CpG methylation in the regulation of ocular tissue-specification and described hypermethylation of retinal transcription factors (i.e., PAX6, RAX, SIX6) in a tissue-dependent manner. Second, we have characterized the DNA methylome of visual disorders linked to internal and external environmental factors. Main conclusions allow certifying that crucial pathways related to Wnt-MAPK signaling pathways or neuroinflammation are epigenetically controlled in the fibrotic disorders involved in retinal detachment, but results also reinforced the contribution of neurovascularization (ETS1, HES5, PRDM16) in diabetic retinopathy. Finally, we had studied the methylome in the most frequent intraocular tumors in adults and children (uveal melanoma and retinoblastoma, respectively). We observed that hypermethylation of tumor suppressor genes is a frequent event in ocular tumors, but also unmethylation is associated with tumorogenesis. Interestingly, unmethylation of the proto-oncogen RAB31 was a predictor of metastasis risk in uveal melanoma. Loss of methylation of the oncogenic mir-17-92 cluster was detected in primary tissues but also in blood from patients.
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Affiliation(s)
- María Berdasco
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain.
| | - Antonio Gómez
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain
| | - Marcos J Rubio
- Department of Ophthalmology, Bellvitge University Hospital, L'Hospitalet de Llobregat, Catalonia, Spain
| | - Jaume Català-Mora
- Hospital Sant Joan de Deu, Esplugues de Llobregat, Barcelona, Catalonia, Spain
| | - Vicente Zanón-Moreno
- Unidad de Epidemiología Molecular y Genética del Departamento de Medicina Preventiva y Salud Pública de la Facultad de Medicina y Odontología y Centro de Investigación en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), Universidad de Valencia, Valencia, Spain
| | - Miguel Lopez
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain
| | - Cristina Hernández
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Catalonia, Spain
| | - Shigeo Yoshida
- Department of Ophthalmology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Takahito Nakama
- Department of Ophthalmology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Keijiro Ishikawa
- Department of Ophthalmology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Tatsuro Ishibashi
- Department of Ophthalmology, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
| | - Amina M Boubekeur
- Faculty of Life and Natural Science, Department of Applied Molecular Genetics, Laboratory of Medical Genetics, University of Science and Technology of Oran, Mohamed Boudiaf, Oran, Algeria
| | - Lotfi Louhibi
- Faculty of Life and Natural Science, Department of Applied Molecular Genetics, Laboratory of Medical Genetics, University of Science and Technology of Oran, Mohamed Boudiaf, Oran, Algeria
| | - Miguel A Pujana
- Cancer Systems Biology Group; Program Against Cancer Therapeutic Resistance (ProCURE); Catalan Institute of Oncology (ICO), Bellvitge Biomedical Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain
| | - Sergi Sayols
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain
| | - Fernando Setien
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain
| | - Dolores Corella
- Unidad de Epidemiología Molecular y Genética del Departamento de Medicina Preventiva y Salud Pública de la Facultad de Medicina y Odontología y Centro de Investigación en Red Fisiopatología de la Obesidad y Nutrición (CIBERobn), Universidad de Valencia, Valencia, Spain
| | - Carmen de Torres
- Hospital Sant Joan de Deu, Esplugues de Llobregat, Barcelona, Catalonia, Spain
| | - Andreu Parareda
- Hospital Sant Joan de Deu, Esplugues de Llobregat, Barcelona, Catalonia, Spain
| | - Jaume Mora
- Hospital Sant Joan de Deu, Esplugues de Llobregat, Barcelona, Catalonia, Spain
| | - Ling Zhao
- Shiley Eye Institute and Institute for Genomic Medicine, University of California, San Diego, La Jolla, United States
| | - Kang Zhang
- Shiley Eye Institute and Institute for Genomic Medicine, University of California, San Diego, La Jolla, United States
| | - Matilde E Lleonart
- Biomedical Research in Cancer Stem Cells Group, Vall d'Hebron Research Institute (VHIR), Barcelona, Catalonia, Spain
| | - Javier Alonso
- Unidad de Tumores Sólidos Infantiles, Instituto de Investigación de Enfermedades Raras, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain
| | - Rafael Simó
- Diabetes and Metabolism Research Unit, Vall d'Hebron Research Institute, Universitat Autònoma de Barcelona, Catalonia, Spain.,Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Madrid, Spain
| | - Josep M Caminal
- Department of Ophthalmology, Bellvitge University Hospital, L'Hospitalet de Llobregat, Catalonia, Spain
| | - Manel Esteller
- Cancer Epigenetics Group; Cancer Epigenetics and Biology Program (PEBC), Bellvitge Biomedical Research Institute (IDIBELL), Barcelona, Catalonia, Spain. .,Department of Physiological Sciences II, School of Medicine, University of Barcelona, Barcelona, Catalonia, Spain. .,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Catalonia, Spain.
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23
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Seritrakul P, Gross JM. Tet-mediated DNA hydroxymethylation regulates retinal neurogenesis by modulating cell-extrinsic signaling pathways. PLoS Genet 2017; 13:e1006987. [PMID: 28926578 PMCID: PMC5621703 DOI: 10.1371/journal.pgen.1006987] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 09/29/2017] [Accepted: 08/18/2017] [Indexed: 12/28/2022] Open
Abstract
DNA hydroxymethylation has recently been shown to play critical roles in regulating gene expression and terminal differentiation events in a variety of developmental contexts. However, little is known about its function during eye development. Methylcytosine dioxygenases of the Tet family convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC), an epigenetic mark thought to serve as a precursor for DNA demethylation and as a stable mark in neurons. Here, we report a requirement for Tet activity during zebrafish retinal neurogenesis. In tet2-/-;tet3-/- mutants, retinal neurons are specified but most fail to terminally differentiate. While differentiation of the first born retinal neurons, the retinal ganglion cells (RGCs), is less affected in tet2-/-;tet3-/- mutants than other retinal cell types, the majority of RGCs do not undergo terminal morphogenesis and form axons. Moreover, the few photoreceptors that differentiate in tet2-/-;tet3-/- mutants fail to form outer segments, suggesting that Tet function is also required for terminal morphogenesis of differentiated retinal neurons. Mosaic analyses revealed a surprising cell non-autonomous requirement for tet2 and tet3 activity in facilitating retinal neurogenesis. Through a combination of candidate gene analysis, transcriptomics and pharmacological manipulations, we identified the Notch and Wnt pathways as cell-extrinsic pathways regulated by tet2 and tet3 activity during RGC differentiation and morphogenesis. Transcriptome analyses also revealed the ectopic expression of non-retinal genes in tet2-/-;tet3-/- mutant retinae, and this correlated with locus-specific reduction in 5hmC. These data provide the first evidence that Tet-dependent regulation of 5hmC formation is critical for retinal neurogenesis, and highlight an additional layer of complexity in the progression from retinal progenitor cell to differentiated retinal neuron during development of the vertebrate retina.
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Affiliation(s)
- Pawat Seritrakul
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States of America
- Departments of Ophthalmology, and Developmental Biology, The Louis J. Fox Center for Vision Restoration, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
| | - Jeffrey M. Gross
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States of America
- Departments of Ophthalmology, and Developmental Biology, The Louis J. Fox Center for Vision Restoration, The McGowan Institute for Regenerative Medicine, The University of Pittsburgh School of Medicine, Pittsburgh, PA, United States of America
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24
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Singh RK, Mallela RK, Hayes A, Dunham NR, Hedden ME, Enke RA, Fariss RN, Sternberg H, West MD, Nasonkin IO. Dnmt1, Dnmt3a and Dnmt3b cooperate in photoreceptor and outer plexiform layer development in the mammalian retina. Exp Eye Res 2017; 159:132-146. [PMID: 27865785 DOI: 10.1016/j.exer.2016.11.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 10/21/2016] [Accepted: 11/14/2016] [Indexed: 11/18/2022]
Abstract
Characterizing the role of epigenetic regulation in the mammalian retina is critical for understanding fundamental mechanisms of retinal development and disease. DNA methylation, an epigenetic modifier of genomic DNA, plays an important role in modulating networks of tissue and cell-specific gene expression. However, the impact of DNA methylation on retinal development and homeostasis of retinal neurons remains unclear. Here, we have created a tissue-specific DNA methyltransferase (Dnmt) triple mutant mouse in an effort to characterize the impact of DNA methylation on retinal development and homeostasis. An Rx-Cre transgene was used to drive targeted mutation of all three murine Dnmt genes in the mouse retina encoding major DNA methylation enzymes DNMT1, DNMT3A and DNMT3B. The triple mutant mice represent a hypomorph model since Dnmt1 catalytic activity was still present and excision of Dnmt3a and Dnmt3b had only about 90% efficiency. Mutation of all three Dnmts resulted in global genomic hypomethylation and dramatic reorganization of the photoreceptor and synaptic layers within retina. Transcriptome and proteomic analyses demonstrated enrichment of dysregulated phototransduction and synaptic genes. The 5 mC signal in triple mutant retina was confined to the central heterochromatin but reduced in the peripheral heterochromatin region of photoreceptor nuclei. In addition, we found a reduction of the 5 mC signal in ganglion cell nuclei. Collectively, this data suggests cooperation of all three Dnmts in the formation and homeostasis of photoreceptors and other retinal neurons within the mammalian retina, and highlight the relevance of epigenetic regulation to sensory retinal disorders and vision loss.
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Affiliation(s)
- Ratnesh K Singh
- Department of Ophthalmology, University of Pittsburgh Medical School, USA.
| | - Ramya K Mallela
- Department of Ophthalmology, University of Pittsburgh Medical School, USA
| | - Abigail Hayes
- Department of Ophthalmology, West Virginia University, USA
| | | | | | - Raymond A Enke
- Department of Biology, James Madison University, USA; Center for Genome and Metagenome Studies, James Madison University, USA
| | - Robert N Fariss
- Biological Imaging Core, National Eye Institute, Bethesda, MD 20892, USA
| | - Hal Sternberg
- BioTime, 1010 Atlantic Avenue, Alameda, CA 94501, USA
| | | | - Igor O Nasonkin
- Department of Ophthalmology, University of Pittsburgh Medical School, USA.
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25
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Mishra S, Peterson K, Yin L, Berger A, Fan J, Wistow G. Accumulation of cholesterol and increased demand for zinc in serum-deprived RPE cells. Mol Vis 2016; 22:1387-1404. [PMID: 28003730 PMCID: PMC5166821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 12/08/2016] [Indexed: 11/03/2022] Open
Abstract
PURPOSE Having observed that confluent ARPE-19 cells (derived from human RPE) survive well in high-glucose serum-free medium (SFM) without further feeding for several days, we investigated the expression profile of RPE cells under the same conditions. METHODS Expression profiles were examined with microarray and quantitative PCR (qPCR) analyses, followed by western blot analysis of key regulated proteins. The effects of low-density lipoprotein (LDL) and zinc supplementation were examined with qPCR. Immunofluorescence was used to localize the LDL receptor and to examine LDL uptake. Cellular cholesterol levels were measured with filipin binding. Expression patterns in primary fetal RPE cells were compared using qPCR. RESULTS Microarray analyses of gene expression in ARPE-19, confirmed with qPCR, showed upregulation of lipid and cholesterol biosynthesis pathways in SFM. At the protein level, the cholesterol synthesis control factor SRBEF2 was activated, and other key lipid synthesis proteins increased. Supplementation of SFM with LDL reversed the upregulation of lipid and cholesterol synthesis genes, but not of cholesterol transport genes. The LDL receptor relocated to the plasma membrane, and LDL uptake was activated by day 5-7 in SFM, suggesting increased demand for cholesterol. Confluent ARPE-19 cells in SFM accumulated intracellular cholesterol, compared with cells supplemented with serum, over 7 days. Over the same time course in SFM, the expression of metallothioneins decreased while the major zinc transporter was upregulated, consistent with a parallel increase in demand for zinc. Supplementation with zinc reversed expression changes for metallothionein genes, but not for other zinc-related genes. Similar patterns of regulation were also seen in primary fetal human RPE cells in SFM. CONCLUSIONS ARPE-19 cells respond to serum deprivation and starvation with upregulation of the lipid and cholesterol pathways, accumulation of intracellular cholesterol, and increased demand for zinc. Similar trends are seen in primary fetal RPE cells. Cholesterol accumulation basal to RPE is a prominent feature of age-related macular degeneration (AMD), while dietary zinc is protective. It is conceivable that accumulating defects in Bruch's membrane and dysfunction of the choriocapillaris could impede transport between RPE and vasculature in AMD. Thus, this pattern of response to serum deprivation in RPE-derived cells may have relevance for some aspects of the progression of AMD.
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Affiliation(s)
- Sanghamitra Mishra
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Katherine Peterson
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Lili Yin
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Alan Berger
- Lowe Family Genomics Core, Johns Hopkins University - School of Medicine, Baltimore, MD
| | - Jianguo Fan
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD
| | - Graeme Wistow
- Section on Molecular Structure and Functional Genomics, National Eye Institute, National Institutes of Health, Bethesda, MD
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26
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Ambati S, Yu P, McKinney EC, Kandasamy MK, Hartzell D, Baile CA, Meagher RB. Adipocyte nuclei captured from VAT and SAT. BMC OBESITY 2016; 3:35. [PMID: 27462403 PMCID: PMC4949929 DOI: 10.1186/s40608-016-0112-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 06/16/2016] [Indexed: 12/11/2022]
Abstract
Background Obesity-related comorbidities are thought to result from the reprogramming of the epigenome in numerous tissues and cell types, and in particular, mature adipocytes within visceral and subcutaneous adipose tissue, VAT and SAT. The cell-type specific chromatin remodeling of mature adipocytes within VAT and SAT is poorly understood, in part, because of the difficulties of isolating and manipulating large fragile mature adipocyte cells from adipose tissues. Methods We constructed MA-INTACT (Mature Adipocyte-Isolation of Nuclei TAgged in specific Cell Types) mice using the adiponectin (ADIPOQ) promoter (ADNp) to tag the surface of mature adipocyte nuclei with a reporter protein. The SUN1mRFP1Flag reporter is comprised of a fragment of the nuclear transmembrane protein SUN1, the fluorescent protein mRFP1, and three copies of the Flag epitope tag. Results Mature adipocyte nuclei were rapidly and efficiently immuno-captured from VAT and SAT (MVA and MSA nuclei, respectively), of MA-INTACT mice. MVA and MSA nuclei contained 1,000 to 10,000-fold higher levels of adipocyte-specific transcripts, ADIPOQ, PPARg2, EDNRB, and LEP, relative to uncaptured nuclei, while the latter expressed higher levels of leukocyte and endothelial cell markers IKZF1, RETN, SERPINF1, SERPINE1, ILF3, and TNFA. MVA and MSA nuclei differentially expressed several factors linked to adipogenesis or obesity-related health risks including CEBPA, KLF2, RETN, SERPINE1, and TNFA. The various nuclear populations dramatically differentially expressed transcripts encoding chromatin remodeler proteins regulating DNA cytosine methylation and hydroxymethylation (TETs, DNMTs, TDG, GADD45s) and nucleosomal histone modification (ARID1A, KAT2B, KDM4A, PRMT1, PRMT5, PAXIP1). Remarkably, MSA and MVA nuclei expressed 200 to 1000-fold higher levels of thermogenic marker transcripts PRDM16 and UCP1. Conclusions The MA-INTACT mouse enables a simple way to perform cell-type specific analysis of highly purified mature adipocyte nuclei from VAT and SAT and increases the statistical significance of data collected on adipocytes. Isolated VAT and SAT adipocyte nuclei expressed distinct patterns of transcripts encoding chromatin remodeling factors and proteins relevant to diabetes, cardiovascular disease, and thermogenesis. The MA-INTACT mouse is an useful model to test the impact of caloric intake, dietary nutrients, exercise, and pharmaceuticals on the epigenome-induced health risks of obesity. Electronic supplementary material The online version of this article (doi:10.1186/s40608-016-0112-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Suresh Ambati
- Department of Genetics, University of Georgia, Athens, GA USA
| | - Ping Yu
- Department of Genetics, University of Georgia, Athens, GA USA
| | | | | | - Diane Hartzell
- Department of Foods and Nutrition, University of Georgia, Athens, GA USA ; Department of Animal and Dairy Science, University of Georgia, Athens, GA USA
| | - Clifton A Baile
- Department of Foods and Nutrition, University of Georgia, Athens, GA USA ; Department of Animal and Dairy Science, University of Georgia, Athens, GA USA
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27
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Yu P, Ji L, Lee KJ, Yu M, He C, Ambati S, McKinney EC, Jackson C, Baile CA, Schmitz RJ, Meagher RB. Subsets of Visceral Adipose Tissue Nuclei with Distinct Levels of 5-Hydroxymethylcytosine. PLoS One 2016; 11:e0154949. [PMID: 27171244 PMCID: PMC4865362 DOI: 10.1371/journal.pone.0154949] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/21/2016] [Indexed: 12/11/2022] Open
Abstract
The reprogramming of cellular memory in specific cell types, and in visceral adipocytes in particular, appears to be a fundamental aspect of obesity and its related negative health outcomes. We explored the hypothesis that adipose tissue contains epigenetically distinct subpopulations of adipocytes that are differentially potentiated to record cellular memories of their environment. Adipocytes are large, fragile, and technically difficult to efficiently isolate and fractionate. We developed fluorescence nuclear cytometry (FNC) and fluorescence activated nuclear sorting (FANS) of cellular nuclei from visceral adipose tissue (VAT) using the levels of the pan-adipocyte protein, peroxisome proliferator-activated receptor gamma-2 (PPARg2), to distinguish classes of PPARg2-Positive (PPARg2-Pos) adipocyte nuclei from PPARg2-Negative (PPARg2-Neg) leukocyte and endothelial cell nuclei. PPARg2-Pos nuclei were 10-fold enriched for most adipocyte marker transcripts relative to PPARg2-Neg nuclei. PPARg2-Pos nuclei showed 2- to 50-fold higher levels of transcripts encoding most of the chromatin-remodeling factors assayed, which regulate the methylation of histones and DNA cytosine (e.g., DNMT1, TET1, TET2, KDM4A, KMT2C, SETDB1, PAXIP1, ARID1A, JMJD6, CARM1, and PRMT5). PPARg2-Pos nuclei were large with decondensed chromatin. TAB-seq demonstrated 5-hydroxymethylcytosine (5hmC) levels were remarkably dynamic in gene bodies of various classes of VAT nuclei, dropping 3.8-fold from the highest quintile of expressed genes to the lowest. In short, VAT-derived adipocytes appear to be more actively remodeling their chromatin than non-adipocytes.
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Affiliation(s)
- Ping Yu
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
| | - Lexiang Ji
- Institute of Bioinformatics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
| | - Kevin J. Lee
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
- GRU-UGA Medical Partnership, University of Georgia Health Sciences Campus, Prince Avenue, Athens, GA, 30602, United States of America
| | - Miao Yu
- Department of Chemistry, University of Chicago, 5735 S Ellis Ave, Chicago, IL, 60637 USA
| | - Chuan He
- Department of Chemistry, University of Chicago, 5735 S Ellis Ave, Chicago, IL, 60637 USA
| | - Suresh Ambati
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
| | - Elizabeth C. McKinney
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
| | - Crystal Jackson
- Abeome Corporation, Athens, GA, 111 Riverbend Road, 30602, United States of America
| | - Clifton A. Baile
- Department of Foods and Nutrition, University of Georgia, 305 Sanford Dr, Athens, GA, 30602, United States of America
| | - Robert J. Schmitz
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
| | - Richard B. Meagher
- Department of Genetics, University of Georgia, 120 East Green Street, Athens, GA, 30602, United States of America
- * E-mail:
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Mo A, Luo C, Davis FP, Mukamel EA, Henry GL, Nery JR, Urich MA, Picard S, Lister R, Eddy SR, Beer MA, Ecker JR, Nathans J. Epigenomic landscapes of retinal rods and cones. eLife 2016; 5:e11613. [PMID: 26949250 PMCID: PMC4798964 DOI: 10.7554/elife.11613] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 02/18/2016] [Indexed: 12/28/2022] Open
Abstract
Rod and cone photoreceptors are highly similar in many respects but they have important functional and molecular differences. Here, we investigate genome-wide patterns of DNA methylation and chromatin accessibility in mouse rods and cones and correlate differences in these features with gene expression, histone marks, transcription factor binding, and DNA sequence motifs. Loss of NR2E3 in rods shifts their epigenomes to a more cone-like state. The data further reveal wide differences in DNA methylation between retinal photoreceptors and brain neurons. Surprisingly, we also find a substantial fraction of DNA hypo-methylated regions in adult rods that are not in active chromatin. Many of these regions exhibit hallmarks of regulatory regions that were active earlier in neuronal development, suggesting that these regions could remain undermethylated due to the highly compact chromatin in mature rods. This work defines the epigenomic landscapes of rods and cones, revealing features relevant to photoreceptor development and function. DOI:http://dx.doi.org/10.7554/eLife.11613.001 Vision in humans is made possible by a light-sensing sheet of cells at the back of the eye called the retina. The surface of the retina is populated by specialized sensory cells, known as rods and cones. The rod cells detect very dim light, while the cones are less sensitive to light but are used to detect color. Together, the rods and cones gather the information needed to create a picture that is then transmitted to the brain. Rods and cones have been studied for decades, and genetic analyses have revealed the patterns of gene expression that lead a cell to develop into either a rod or a cone. Researchers have also identified several key regulatory genes that control these patterns, but less is known about the role of other factors that control the expression of genes. Chemical modifications to DNA or modifications to the proteins associated with DNA – which are collectively called epigenetic modifications – can either promote or inhibit the activation of nearby genes. Now, Mo et al. have shown that rods and cones from mice have very different patterns of epigenetic modifications. The experiments also revealed that many sections of DNA that are marked to promote gene activation contain known rod-specific or cone-specific genes; and that rod cells need a known regulatory gene to develop their specific pattern of epigenetic modifications. Finally, Mo et al. showed that epigenetic regulation differed between brain cells and rods and cones. These insights into epigenetic regulation of rod and cone genes may help explain why some people with eye diseases caused by the same genetic mutation may develop symptoms at different ages or lose vision at different rates. The new information about gene regulation may also help scientists to reprogram stem cells to become healthy rods or cones that could be transplanted into people with eye disease to restore their vision. DOI:http://dx.doi.org/10.7554/eLife.11613.002
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Affiliation(s)
- Alisa Mo
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Chongyuan Luo
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, United States
| | - Fred P Davis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Eran A Mukamel
- Department of Cognitive Science, University of California San Diego, La Jolla, United States
| | - Gilbert L Henry
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Joseph R Nery
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Mark A Urich
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, United States
| | - Serge Picard
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Ryan Lister
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,The ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, Crawley, Australia
| | - Sean R Eddy
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Michael A Beer
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, United States
| | - Joseph R Ecker
- Genomic Analysis Laboratory, The Salk Institute for Biological Studies, La Jolla, United States.,Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, United States
| | - Jeremy Nathans
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, United States.,Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
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29
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Kessler NJ, Van Baak TE, Baker MS, Laritsky E, Coarfa C, Waterland RA. CpG methylation differences between neurons and glia are highly conserved from mouse to human. Hum Mol Genet 2015; 25:223-32. [PMID: 26566671 DOI: 10.1093/hmg/ddv459] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 11/05/2015] [Indexed: 01/13/2023] Open
Abstract
Understanding epigenetic differences that distinguish neurons and glia is of fundamental importance to the nascent field of neuroepigenetics. A recent study used genome-wide bisulfite sequencing to survey differences in DNA methylation between these two cell types, in both humans and mice. That study minimized the importance of cell type-specific differences in CpG methylation, claiming these are restricted to localized genomic regions, and instead emphasized that widespread and highly conserved differences in non-CpG methylation distinguish neurons and glia. We reanalyzed the data from that study and came to markedly different conclusions. In particular, we found widespread cell type-specific differences in CpG methylation, with a genome-wide tendency for neuronal CpG-hypermethylation punctuated by regions of glia-specific hypermethylation. Alarmingly, our analysis indicated that the majority of genes identified by the primary study as exhibiting cell type-specific CpG methylation differences were misclassified. To verify the accuracy of our analysis, we isolated neuronal and glial DNA from mouse cortex and performed quantitative bisulfite pyrosequencing at nine loci. The pyrosequencing results corroborated our analysis, without exception. Most interestingly, we found that gene-associated neuron vs. glia CpG methylation differences are highly conserved across human and mouse, and are very likely to be functional. In addition to underscoring the importance of independent verification to confirm the conclusions of genome-wide epigenetic analyses, our data indicate that CpG methylation plays a major role in neuroepigenetics, and that the mouse is likely an excellent model in which to study the role of DNA methylation in human neurodevelopment and disease.
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Affiliation(s)
| | | | | | | | | | - Robert A Waterland
- Department of Pediatrics, Department of Molecular & Human Genetics, Baylor College of Medicine, USDA/ARS Children's Nutrition Research Center,Houston, TX, USA
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30
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Yang HJ, Ratnapriya R, Cogliati T, Kim JW, Swaroop A. Vision from next generation sequencing: multi-dimensional genome-wide analysis for producing gene regulatory networks underlying retinal development, aging and disease. Prog Retin Eye Res 2015; 46:1-30. [PMID: 25668385 PMCID: PMC4402139 DOI: 10.1016/j.preteyeres.2015.01.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 01/18/2015] [Accepted: 01/21/2015] [Indexed: 01/10/2023]
Abstract
Genomics and genetics have invaded all aspects of biology and medicine, opening uncharted territory for scientific exploration. The definition of "gene" itself has become ambiguous, and the central dogma is continuously being revised and expanded. Computational biology and computational medicine are no longer intellectual domains of the chosen few. Next generation sequencing (NGS) technology, together with novel methods of pattern recognition and network analyses, has revolutionized the way we think about fundamental biological mechanisms and cellular pathways. In this review, we discuss NGS-based genome-wide approaches that can provide deeper insights into retinal development, aging and disease pathogenesis. We first focus on gene regulatory networks (GRNs) that govern the differentiation of retinal photoreceptors and modulate adaptive response during aging. Then, we discuss NGS technology in the context of retinal disease and develop a vision for therapies based on network biology. We should emphasize that basic strategies for network construction and analyses can be transported to any tissue or cell type. We believe that specific and uniform guidelines are required for generation of genome, transcriptome and epigenome data to facilitate comparative analysis and integration of multi-dimensional data sets, and for constructing networks underlying complex biological processes. As cellular homeostasis and organismal survival are dependent on gene-gene and gene-environment interactions, we believe that network-based biology will provide the foundation for deciphering disease mechanisms and discovering novel drug targets for retinal neurodegenerative diseases.
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Affiliation(s)
- Hyun-Jin Yang
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-0610, USA
| | - Rinki Ratnapriya
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-0610, USA
| | - Tiziana Cogliati
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-0610, USA
| | - Jung-Woong Kim
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-0610, USA
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, 6 Center Drive, Bethesda, MD 20892-0610, USA.
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31
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Putnik M, Wojdacz TK, Pournara A, Vahter M, Wallberg AE. MS-HRM assay identifies high levels of epigenetic heterogeneity in human immortalized cell lines. Gene 2015; 560:165-72. [DOI: 10.1016/j.gene.2015.01.063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/29/2015] [Indexed: 02/08/2023]
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32
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Yu P, McKinney EC, Kandasamy MM, Albert AL, Meagher RB. Characterization of brain cell nuclei with decondensed chromatin. Dev Neurobiol 2014; 75:738-56. [PMID: 25369517 DOI: 10.1002/dneu.22245] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 10/22/2014] [Accepted: 10/30/2014] [Indexed: 12/14/2022]
Abstract
Although multipotent cell types have enlarged nuclei with decondensed chromatin, this property has not been exploited to enhance the characterization of neural progenitor cell (NPC) populations in the brain. We found that mouse brain cell nuclei that expressed exceptionally high levels of the pan neuronal marker NeuN/FOX3 (NeuN-High) had decondensed chromatin relative to most NeuN-Low or NeuN-Neg (negative) nuclei. Purified NeuN-High nuclei expressed significantly higher levels of transcripts encoding markers of neurogenesis, neuroplasticity, and learning and memory (ARC, BDNF, ERG1, HOMER1, NFL/NEF1, SYT1), subunits of chromatin modifying machinery (SIRT1, HDAC1, HDAC2, HDAC11, KAT2B, KAT3A, KAT3B, KAT5, DMNT1, DNMT3A, Gadd45a, Gadd45b) and markers of NPC and cell cycle activity (BRN2, FOXG1, KLF4, c-MYC, OCT4, PCNA, SHH, SOX2) relative to neuronal NeuN-Low or to mostly non-neuronal NeuN-Neg nuclei. NeuN-High nuclei expressed higher levels of HDAC1, 2, 4, and 5 proteins. The cortex, hippocampus, hypothalamus, thalamus, and nucleus accumbens contained high percentages of large decondensed NeuN-High nuclei, while the cerebellum, and pons contained very few. NeuN-High nuclei have the properties consistent with their being derived from extremely active neurons with elevated rates of chromatin modification and/or NPC-like cells with multilineage developmental potential. The further analysis of decondensed neural cell nuclei should provide novel insights into neurobiology and neurodegenerative disease.
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Affiliation(s)
- Ping Yu
- Department of Genetics, University of Georgia, Davison Life Sciences Building, Athens, Georgia, 30602
| | - Elizabeth C McKinney
- Department of Genetics, University of Georgia, Davison Life Sciences Building, Athens, Georgia, 30602
| | - Muthugapatti M Kandasamy
- Department of Genetics, University of Georgia, Davison Life Sciences Building, Athens, Georgia, 30602
| | | | - Richard B Meagher
- Department of Genetics, University of Georgia, Davison Life Sciences Building, Athens, Georgia, 30602
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33
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Oliver VF, Franchina M, Jaffe AE, Branham KE, Othman M, Heckenlively JR, Swaroop A, Campochiaro B, Vote BJ, Craig JE, Saffery R, Mackey DA, Qian J, Zack DJ, Hewitt AW, Merbs SL. Hypomethylation of the IL17RC promoter in peripheral blood leukocytes is not a hallmark of age-related macular degeneration. Cell Rep 2014; 5:1527-35. [PMID: 24373284 DOI: 10.1016/j.celrep.2013.11.042] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/25/2013] [Accepted: 11/26/2013] [Indexed: 01/06/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of visual impairment worldwide. Aberrant DNA methylation within the promoter of IL17RC in peripheral blood mononuclear cells has recently been reported in AMD. To validate this association, we examined DNA methylation of the IL17RC promoter in peripheral blood. First, we used Illumina Human Methylation450 Bead Arrays, a widely accepted platform for measuring global DNA methylation. Second, methylation status at multiple sites within the IL17RC promoter was determined by bisulfite pyrosequencing in two cohorts. Third, a methylation-sensitive quantitative PCR-based assay was performed on a subset of samples. In contrast to previous findings, we did not find evidence of differential methylation between AMD cases and age-matched controls. We conclude that hypomethylation within the IL17RC gene promoter in peripheral blood is not suitable for use as a clinical biomarker of AMD. This study highlights the need for considerable replication of epigenetic association studies prior to clinical application.
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Affiliation(s)
- Verity F Oliver
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA
| | - Maria Franchina
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, WA 6009, Australia
| | - Andrew E Jaffe
- Lieber Institute for Brain Development, Johns Hopkins Medical Campus, Baltimore, MD 21287, USA
| | - Kari E Branham
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
| | - Mohammad Othman
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
| | - John R Heckenlively
- Kellogg Eye Center, Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI 48105, USA
| | - Anand Swaroop
- National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Betsy Campochiaro
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA
| | - Brendan J Vote
- Launceston Eye Institute, University of Tasmania, Launceston 7249, Australia
| | - Jamie E Craig
- Department of Ophthalmology, Flinders University, Flinders Medical Centre, Adelaide, SA 5042, Australia
| | - Richard Saffery
- Cancer and Disease Epigenetics, Murdoch Childrens Research Institute, University of Melbourne, Royal Children's Hospital, Melbourne, VIC 3052, Australia
| | - David A Mackey
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, WA 6009, Australia
| | - Jiang Qian
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA
| | - Donald J Zack
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA; Department of Molecular Biology and Genetics, Department of Neuroscience, and Institute of Genetic Medicine, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA; Institut de la Vision, Université Pierre et Marie Curie, Paris 75012, France
| | - Alex W Hewitt
- Centre for Ophthalmology and Visual Science, University of Western Australia, Lions Eye Institute, Perth, WA 6009, Australia; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia.
| | - Shannath L Merbs
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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Seritrakul P, Gross JM. Expression of the de novo DNA methyltransferases (dnmt3 - dnmt8) during zebrafish lens development. Dev Dyn 2013; 243:350-6. [PMID: 24123478 DOI: 10.1002/dvdy.24077] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 09/10/2013] [Accepted: 10/03/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND De novo DNA methylation is thought to be critical for cellular reprogramming during tissue differentiation and development. Little is known about the roles of de novo DNA methylation during eye development, and particularly during lens development. The lens is composed of lens epithelial (LE) and lens fiber (LF) cells, with proliferative LE cells giving rise to differentiated LFs at the "transition zone." Given the unique architecture and developmental program of the lens, and the involvement of de novo DNA methylation during differentiation events in other tissues, we sought to identify de novo DNA methyltransferases expressed in the zebrafish lens. RESULTS Zebrafish possess six de novo DNA methyltransferase genes, dnmt3 - dnmt8. At 24 hr postfertilization (hpf), all six are expressed ubiquitously throughout the eye. By 72 hpf, dnmt3 and dnmt5 become restricted to cells of the retinal ciliary marginal zone (CMZ), dnmt4 and dnmt7 to cells of the CMZ and LE, and dnmt6 and dnmt8 to ganglion cells and cells of the inner nuclear layer of the retina. CONCLUSIONS These data identify regions of the eye where de novo methyltransferases could mediate DNA methylation events during development. Overlapping expression domains also suggest functional redundancy within this gene family in the eye.
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Affiliation(s)
- Pawat Seritrakul
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas
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Wahlin KJ, Enke RA, Fuller JA, Kalesnykas G, Zack DJ, Merbs SL. Epigenetics and cell death: DNA hypermethylation in programmed retinal cell death. PLoS One 2013; 8:e79140. [PMID: 24244436 PMCID: PMC3823652 DOI: 10.1371/journal.pone.0079140] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 09/17/2013] [Indexed: 12/01/2022] Open
Abstract
Background Vertebrate genomes undergo epigenetic reprogramming during development and disease. Emerging evidence suggests that DNA methylation plays a key role in cell fate determination in the retina. Despite extensive studies of the programmed cell death that occurs during retinal development and degeneration, little is known about how DNA methylation might regulate neuronal cell death in the retina. Methods The developing chicken retina and the rd1 and rhodopsin-GFP mouse models of retinal degeneration were used to investigate programmed cell death during retinal development and degeneration. Changes in DNA methylation were determined by immunohistochemistry using antibodies against 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC). Results Punctate patterns of hypermethylation paralleled patterns of caspase3-dependent apoptotic cell death previously reported to occur during development in the chicken retina. Degenerating rd1 mouse retinas, at time points corresponding to the peak of rod cell death, showed elevated signals for 5mC and 5hmC in photoreceptors throughout the retina, with the most intense staining observed in the peripheral retina. Hypermethylation of photoreceptors in rd1 mice was associated with TUNEL and PAR staining and appeared to be cCaspase3-independent. After peak rod degeneration, during the period of cone death, occasional hypermethylation was observed in the outer nuclear layer. Conclusion The finding that cell-specific increases of 5mC and 5hmC immunostaining are associated with the death of retinal neurons during both development and degeneration suggests that changes in DNA methylation may play a role in modulating gene expression during the process of retinal degeneration. During retinal development, hypermethylation of retinal neurons associates with classical caspase-dependent apoptosis as well as caspase-3 independent cell death, while hypermethylation in the rd1 mouse photoreceptors is primarily associated with caspase-3 independent programmed cell death. These findings suggest a previously unrecognized role for epigenetic mechanisms in the onset and/or progression of programed cell death in the retina.
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Affiliation(s)
- Karl J. Wahlin
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Raymond A. Enke
- Department of Biology, James Madison University, Harrisonburg, Virginia, United States of America
| | - John A. Fuller
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Giedrius Kalesnykas
- Department of Ophthalmology, Clinical Research Unit, School of Medicine, University of Eastern Finland, Kuopio, Finland
| | - Donald J. Zack
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Institute de la Vision, Université Pierre et Marie Curie, Paris, France
| | - Shannath L. Merbs
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Liu MM, Chan CC, Tuo J. Epigenetics in ocular diseases. Curr Genomics 2013; 14:166-72. [PMID: 24179439 PMCID: PMC3664466 DOI: 10.2174/1389202911314030002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 02/21/2013] [Accepted: 02/25/2013] [Indexed: 01/23/2023] Open
Abstract
Epigenetics pertains to heritable alterations in gene expression that do not involve modification of the underlying genomic DNA sequence. Historically, the study of epigenetic mechanisms has focused on DNA methylation and histone modifications, but the concept of epigenetics has been more recently extended to include microRNAs as well. Epigenetic patterning is modified by environmental exposures and may be a mechanistic link between environmental risk factors and the development of disease. Epigenetic dysregulation has been associated with a variety of human diseases, including cancer, neurological disorders, and autoimmune diseases. In this review, we consider the role of epigenetics in common ocular diseases, with a particular focus on DNA methylation and microRNAs. DNA methylation is a critical regulator of gene expression in the eye and is necessary for the proper development and postmitotic survival of retinal neurons. Aberrant methylation patterns have been associated with age-related macular degeneration, susceptibility to oxidative stress, cataract, pterygium, and retinoblastoma. Changes in histone modifications have also been observed in experimental models of diabetic retinopathy and glaucoma. The expression levels of specific microRNAs have also been found to be altered in the context of ocular inflammation, retinal degeneration, pathological angiogenesis, diabetic retinopathy, and ocular neoplasms. Although the complete spectrum of epigenetic modifications remains to be more fully explored, it is clear that epigenetic dysregulation is an important contributor to common ocular diseases and may be a relevant therapeutic target.
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Affiliation(s)
- Melissa M Liu
- Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD ; Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Ratnapriya R, Swaroop A. Genetic architecture of retinal and macular degenerative diseases: the promise and challenges of next-generation sequencing. Genome Med 2013; 5:84. [PMID: 24112618 PMCID: PMC4066589 DOI: 10.1186/gm488] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Inherited retinal degenerative diseases (RDDs) display wide variation in their mode of inheritance, underlying genetic defects, age of onset, and phenotypic severity. Molecular mechanisms have not been delineated for many retinal diseases, and treatment options are limited. In most instances, genotype-phenotype correlations have not been elucidated because of extensive clinical and genetic heterogeneity. Next-generation sequencing (NGS) methods, including exome, genome, transcriptome and epigenome sequencing, provide novel avenues towards achieving comprehensive understanding of the genetic architecture of RDDs. Whole-exome sequencing (WES) has already revealed several new RDD genes, whereas RNA-Seq and ChIP-Seq analyses are expected to uncover novel aspects of gene regulation and biological networks that are involved in retinal development, aging and disease. In this review, we focus on the genetic characterization of retinal and macular degeneration using NGS technology and discuss the basic framework for further investigations. We also examine the challenges of NGS application in clinical diagnosis and management.
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Affiliation(s)
- Rinki Ratnapriya
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Anand Swaroop
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Masser DR, Berg AS, Freeman WM. Focused, high accuracy 5-methylcytosine quantitation with base resolution by benchtop next-generation sequencing. Epigenetics Chromatin 2013; 6:33. [PMID: 24279302 PMCID: PMC3907040 DOI: 10.1186/1756-8935-6-33] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 09/25/2013] [Indexed: 01/14/2023] Open
Abstract
Background The growing interest in the role of epigenetic modifications in human health and disease has led to the development of next-generation sequencing methods for whole genome analysis of DNA methylation patterns. However, many projects require targeted methylation analysis of specific genes or genomic regions. We have developed an approach, termed BiSulfite Amplicon Sequencing (BSAS), for hypothesis driven and focused absolute DNA methylation analysis. This approach is applicable both to targeted DNA methylation studies as well as to confirmation of genome-wide studies. Results BSAS uses PCR enrichment of targeted regions from bisulfite-converted DNA and transposome-mediated library construction for rapid generation of sequencing libraries from low (1 ng) sample input. Libraries are sequenced using the Illumina MiSeq benchtop sequencer. Generating high levels of sequencing depth (>1,000 ×) provides for quantitatively precise and accurate assessment of DNA methylation levels with base specificity. Dual indexing of sequencing libraries allows for simultaneous analysis of up to 96 samples. We demonstrate the superior quantitative accuracy of this approach as compared to existing Sanger sequencing methods. Conclusions BSAS can be applied to any genomic region from any DNA source, including tissue and cell culture. Thus, BSAS provides a new validation approach for rapid and highly quantitative absolute CpG methylation analysis of any targeted genomic regions in a high throughput manner.
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Wan J, Oliver VF, Zhu H, Zack DJ, Qian J, Merbs SL. Integrative analysis of tissue-specific methylation and alternative splicing identifies conserved transcription factor binding motifs. Nucleic Acids Res 2013; 41:8503-14. [PMID: 23887936 PMCID: PMC3794605 DOI: 10.1093/nar/gkt652] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The exact role of intragenic DNA methylation in regulating tissue-specific gene regulation is unclear. Recently, the DNA-binding protein CTCF has been shown to participate in the regulation of alternative splicing in a DNA methylation-dependent manner. To globally evaluate the relationship between DNA methylation and tissue-specific alternative splicing, we performed genome-wide DNA methylation profiling of mouse retina and brain. In protein-coding genes, tissue-specific differentially methylated regions (T-DMRs) were preferentially located in exons and introns. Gene ontology and evolutionary conservation analysis suggest that these T-DMRs are likely to be biologically relevant. More than 14% of alternatively spliced genes were associated with a T-DMR. T-DMR-associated genes were enriched for developmental genes, suggesting that a specific set of alternatively spliced genes may be regulated through DNA methylation. Novel DNA sequences motifs overrepresented in T-DMRs were identified as being associated with positive and/or negative regulation of alternative splicing in a position-dependent context. The majority of these evolutionarily conserved motifs contain a CpG dinucleotide. Some transcription factors, which recognize these motifs, are known to be involved in splicing. Our results suggest that DNA methylation-dependent alternative splicing is widespread and lay the foundation for further mechanistic studies of the role of DNA methylation in tissue-specific splicing regulation.
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Affiliation(s)
- Jun Wan
- Department of Ophthalmology, Wilmer Institute, Johns Hopkins University School of Medicine, 600 North Wolfe Street, 21287 Baltimore, MD, USA, Department of Pharmacology and Molecular Science, Johns Hopkins University School of Medicine, 600 North Wolfe Street, 21287 Baltimore, MD, USA, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, 600 North Wolfe Street, 21287 Baltimore, MD, USA, Department of Neuroscience, Johns Hopkins University School of Medicine, 600 North Wolfe Street, 21287 Baltimore, MD, USA, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, 600 North Wolfe Street, 21287 Baltimore, MD, USA and Institut de la Vision, 17 rue Moreau, 75012 Paris, France
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Ishida M, Okazaki E, Tsukamoto S, Kimura K, Aizawa A, Kito S, Imai H, Minami N. The promoter of the oocyte-specific gene, Oog1, functions in both male and female meiotic germ cells in transgenic mice. PLoS One 2013; 8:e68686. [PMID: 23894331 PMCID: PMC3718783 DOI: 10.1371/journal.pone.0068686] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 06/02/2013] [Indexed: 12/05/2022] Open
Abstract
Oog1 is an oocyte-specific gene whose expression is turned on in mouse oocytes at embryonic day (E) 15.5, concomitant with the time when most of the female germ cells stop proliferating and enter meiotic prophase. Here, we characterize the Oog1 promoter, and show that transgenic GFP reporter expression driven by the 2.7 kb and 3.9 kb regions upstream of the Oog1 transcription start site recapitulates the intrinsic Oog1 expression pattern. In addition, the 3.9 kb upstream region exhibits stronger transcriptional activity than does the 2.7 kb region, suggesting that regulatory functions might be conserved in the additional 1.2 kb region found within the 3.9 kb promoter. Interestingly, the longer promoter (3.9 kb) also showed strong activity in male germ cells, from late pachytene spermatocytes to elongated spermatids. This is likely due to the aberrant demethylation of two CpG sites in the proximal promoter region. One was highly methylated in the tissues in which GFP expression was suppressed, and another was completely demethylated only in Oog1pro3.9 male and female germ cells. These results suggest that aberrant demethylation of the proximal promoter region induced ectopic expression in male germ cells under the control of 3.9 kb Oog1 promoter. This is the first report indicating that sex-dependent gene expression is altered according to the length and the methylation status of the promoter region. Additionally, our results show that individual CpG sites are differentially methylated and play different roles in regulating promoter activity and gene transcription.
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Affiliation(s)
- Miya Ishida
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Eriko Okazaki
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Satoshi Tsukamoto
- Laboratory of Animal and Genome Science Section, National Institute of Radiological Sciences, Chiba, Japan
| | - Koji Kimura
- Animal Reproduction Laboratory, National Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Nasushiobara, Japan
| | | | - Seiji Kito
- Laboratory of Animal and Genome Science Section, National Institute of Radiological Sciences, Chiba, Japan
| | - Hiroshi Imai
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Naojiro Minami
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- * E-mail:
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Oliver VF, Wan J, Agarwal S, Zack DJ, Qian J, Merbs SL. A novel methyl-binding domain protein enrichment method for identifying genome-wide tissue-specific DNA methylation from nanogram DNA samples. Epigenetics Chromatin 2013; 6:17. [PMID: 23759032 PMCID: PMC3680319 DOI: 10.1186/1756-8935-6-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/13/2013] [Indexed: 02/08/2023] Open
Abstract
Background Growing evidence suggests that DNA methylation plays a role in tissue-specific differentiation. Current approaches to methylome analysis using enrichment with the methyl-binding domain protein (MBD) are restricted to large (≥1 μg) DNA samples, limiting the analysis of small tissue samples. Here we present a technique that enables characterization of genome-wide tissue-specific methylation patterns from nanogram quantities of DNA. Results We have developed a methodology utilizing MBD2b/MBD3L1 enrichment for methylated DNA, kinase pre-treated ligation-mediated PCR amplification (MeKL) and hybridization to the comprehensive high-throughput array for relative methylation (CHARM) customized tiling arrays, which we termed MeKL-chip. Kinase modification in combination with the addition of PEG has increased ligation-mediated PCR amplification over 20-fold, enabling >400-fold amplification of starting DNA. We have shown that MeKL-chip can be applied to as little as 20 ng of DNA, enabling comprehensive analysis of small DNA samples. Applying MeKL-chip to the mouse retina (a limited tissue source) and brain, 2,498 tissue-specific differentially methylated regions (T-DMRs) were characterized. The top five T-DMRs (Rgs20, Hes2, Nfic, Cckbr and Six3os1) were validated by pyrosequencing. Conclusions MeKL-chip enables genome-wide methylation analysis of nanogram quantities of DNA with a wide range of observed-to-expected CpG ratios due to the binding properties of the MBD2b/MBD3L1 protein complex. This methodology enabled the first analysis of genome-wide methylation in the mouse retina, characterizing novel T-DMRs.
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Affiliation(s)
- Verity F Oliver
- Department of Ophthalmology, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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Nasonkin IO, Merbs SL, Lazo K, Oliver VF, Brooks M, Patel K, Enke RA, Nellissery J, Jamrich M, Le YZ, Bharti K, Fariss RN, Rachel RA, Zack DJ, Rodriguez-Boulan EJ, Swaroop A. Conditional knockdown of DNA methyltransferase 1 reveals a key role of retinal pigment epithelium integrity in photoreceptor outer segment morphogenesis. Development 2013; 140:1330-41. [PMID: 23406904 DOI: 10.1242/dev.086603] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dysfunction or death of photoreceptors is the primary cause of vision loss in retinal and macular degenerative diseases. As photoreceptors have an intimate relationship with the retinal pigment epithelium (RPE) for exchange of macromolecules, removal of shed membrane discs and retinoid recycling, an improved understanding of the development of the photoreceptor-RPE complex will allow better design of gene- and cell-based therapies. To explore the epigenetic contribution to retinal development we generated conditional knockout alleles of DNA methyltransferase 1 (Dnmt1) in mice. Conditional Dnmt1 knockdown in early eye development mediated by Rx-Cre did not produce lamination or cell fate defects, except in cones; however, the photoreceptors completely lacked outer segments despite near normal expression of phototransduction and cilia genes. We also identified disruption of RPE morphology and polarization as early as E15.5. Defects in outer segment biogenesis were evident with Dnmt1 exon excision only in RPE, but not when excision was directed exclusively to photoreceptors. We detected a reduction in DNA methylation of LINE1 elements (a measure of global DNA methylation) in developing mutant RPE as compared with neural retina, and of Tuba3a, which exhibited dramatically increased expression in mutant retina. These results demonstrate a unique function of DNMT1-mediated DNA methylation in controlling RPE apicobasal polarity and neural retina differentiation. We also establish a model to study the epigenetic mechanisms and signaling pathways that guide the modulation of photoreceptor outer segment morphogenesis by RPE during retinal development and disease.
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Affiliation(s)
- Igor O Nasonkin
- 1Neurobiology-Neurodegeneration and Repair Laboratory (N-NRL), National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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From quantitative protein complex analysis to disease mechanism. Vision Res 2012; 75:108-11. [PMID: 23010258 DOI: 10.1016/j.visres.2012.08.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 11/22/2022]
Abstract
Interest in the field of cilia biology and cilia-associated diseases - ciliopathies - has strongly increased over the last few years. Proteomic technologies, especially protein complex analysis by affinity purification-based methods, have been used to decipher various basic but also disease-associated mechanisms. This review focusses on some selected recent studies using affinity purification-based protein complex analysis, thereby exemplifying the great possibilities this technology offers.
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Rhee KD, Yu J, Zhao CY, Fan G, Yang XJ. Dnmt1-dependent DNA methylation is essential for photoreceptor terminal differentiation and retinal neuron survival. Cell Death Dis 2012; 3:e427. [PMID: 23171847 PMCID: PMC3542601 DOI: 10.1038/cddis.2012.165] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Epigenetic regulation of the genome is critical for the emergence of diverse cell lineages during development. To understand the role of DNA methylation during retinal network formation, we generated a mouse retinal-specific Dnmt1 deletion mutation from the onset of neurogenesis. In the hypomethylated Dnmt1-mutant retina, neural progenitor cells continue to proliferate, however, the cell cycle progression is altered, as revealed by an increased proportion of G1 phase cells. Despite production of all major retinal neuronal cell types in the Dnmt1-mutant retina, various postmitotic neurons show defective differentiation, including ectopic cell soma and aberrant dendritic morphologies. Specifically, the commitment of Dmnt1-deficient progenitors towards the photoreceptor fate is not affected by DNA hypomethylation, yet the initiation of photoreceptor differentiation is severely hindered, resulting in reduction and mislocalization of rhodopsin-expressing cells. In addition to compromised neuronal differentiation, Dnmt1 deficiency also leads to rapid cell death of photoreceptors and other types of neurons in the postnatal retina. These results indicate that Dnmt1-dependent DNA methylation is critical for expansion of the retinal progenitor pool, as well as for maturation and survival of postmitotic neurons.
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Affiliation(s)
- K-D Rhee
- Jules Stein Eye Institute, University of California, Los Angeles, CA 90095, USA
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Affiliation(s)
- Barkur S. Shastry
- Department of Biological Sciences; Oakland University; Rochester; MI ; 48309; USA
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Meagher RB, Müssar KJ. The influence of DNA sequence on epigenome-induced pathologies. Epigenetics Chromatin 2012; 5:11. [PMID: 22818522 PMCID: PMC3439399 DOI: 10.1186/1756-8935-5-11] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 07/20/2012] [Indexed: 01/13/2023] Open
Abstract
Clear cause-and-effect relationships are commonly established between genotype and the inherited risk of acquiring human and plant diseases and aberrant phenotypes. By contrast, few such cause-and-effect relationships are established linking a chromatin structure (that is, the epitype) with the transgenerational risk of acquiring a disease or abnormal phenotype. It is not entirely clear how epitypes are inherited from parent to offspring as populations evolve, even though epigenetics is proposed to be fundamental to evolution and the likelihood of acquiring many diseases. This article explores the hypothesis that, for transgenerationally inherited chromatin structures, "genotype predisposes epitype", and that epitype functions as a modifier of gene expression within the classical central dogma of molecular biology. Evidence for the causal contribution of genotype to inherited epitypes and epigenetic risk comes primarily from two different kinds of studies discussed herein. The first and direct method of research proceeds by the examination of the transgenerational inheritance of epitype and the penetrance of phenotype among genetically related individuals. The second approach identifies epitypes that are duplicated (as DNA sequences are duplicated) and evolutionarily conserved among repeated patterns in the DNA sequence. The body of this article summarizes particularly robust examples of these studies from humans, mice, Arabidopsis, and other organisms. The bulk of the data from both areas of research support the hypothesis that genotypes predispose the likelihood of displaying various epitypes, but for only a few classes of epitype. This analysis suggests that renewed efforts are needed in identifying polymorphic DNA sequences that determine variable nucleosome positioning and DNA methylation as the primary cause of inherited epigenome-induced pathologies. By contrast, there is very little evidence that DNA sequence directly determines the inherited positioning of numerous and diverse post-translational modifications of histone side chains within nucleosomes. We discuss the medical and scientific implications of these observations on future research and on the development of solutions to epigenetically induced disorders.
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Affiliation(s)
- Richard B Meagher
- Genetics Department, Davison Life Sciences Building, University of Georgia, Athens, GA, 30605, USA.
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Temming P, Corson TW, Lohmann DR. Retinoblastoma tumorigenesis: genetic and epigenetic changes walk hand in hand. Future Oncol 2012; 8:525-8. [DOI: 10.2217/fon.12.41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Evaluation of: Zhang J, Benavente CA, McEvoy J et al. A novel retinoblastoma therapy from genomic and epigenetic analyses. Nature 481(7381), 329–334 (2012). The rate-limiting step in retinoblastoma tumorigenesis is inactivation of both RB1 alleles, but it has remained unclear how this tumor acquires the additional changes that constitute a malignant phenotype. Zhang et al. characterized the genetic and epigenetic alterations in four retinoblastomas using whole-genome analysis techniques. In these samples, the retinoblastoma genome was found to be remarkably stable genetically, although recurrent mutations in BCOR were identified in 13% of patients. However, an approach that integrated the results of ChIP, methylation and expression analysis identified multiple, more frequent alterations of the epigenetic landscape. One of the leading genes on the list the authors obtained was SYK, a kinase epigenetically upregulated. Knockdown of this gene and exposure to small molecules inhibiting the kinase function stopped tumor growth in vitro and in vivo, thus offering a new therapeutic target for the treatment of retinoblastoma.
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Affiliation(s)
- Petra Temming
- Eye Oncogenetics Research Group, Department of Human Genetics, Essen, Germany
- Department of Pediatric Hematology and Oncology, University Children’s Hospital Essen, Essen, Germany
| | - Timothy W Corson
- Eugene & Marilyn Glick Eye Institute, Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Dietmar R Lohmann
- Eye Oncogenetics Research Group, Department of Human Genetics, Essen, Germany
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