1
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Kodosaki E, Daniels-Morgan A, Hassan N, Webb R, Morris K, Kelly CM. Development and characterisation of mgTHP-1, a novel in vitro model for neural macrophages with microglial characteristics. Neurol Res 2024; 46:1-13. [PMID: 37935114 DOI: 10.1080/01616412.2023.2257422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 04/23/2023] [Indexed: 11/09/2023]
Abstract
Neuroinflammation is primarily characterised by activation of the brain's resident macrophages - the microglia. However, other central nervous system (CNS) cells also contribute to this response, including the astrocytes and endothelial cells. In addition, there is infiltration into the CNS of peripherally derived immune cells. Together these cells mediate inflammation by the production of cytokines, chemokines, reactive oxygen species, and secondary messengers, and enacting of the appropriate response to those signals. However, deciphering the specific contributions of each cell type has been challenging. Studying CNS cell biology is often challenging, as the isolation of primary cells is not always feasible, and differentiation towards microglia-like cells is complex. Here, we demonstrate a novel method whereby THP-1 monocytic cells are differentiated into neural macrophage cells with microglia-like cell characteristics. The cells, designated mgTHP-1, show typical morphological and gene expression patterns of resident CNS macrophages and functionally respond to inflammatory stimuli by producing inflammatory cytokines. Furthermore, with the addition of Vicenin-2 (an anti-inflammatory flavonoid) such responses can be reversed. This novel cell model will allow further investigations, and hence insights, into the neuroinflammatory mechanisms associated with CNS diseases.
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Affiliation(s)
- E Kodosaki
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - A Daniels-Morgan
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - N Hassan
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - R Webb
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - K Morris
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
| | - C M Kelly
- Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK
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2
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Li T, Wei Y, Qu M, Mou L, Miao J, Xi M, Liu Y, He R. Formaldehyde and De/Methylation in Age-Related Cognitive Impairment. Genes (Basel) 2021; 12:genes12060913. [PMID: 34199279 PMCID: PMC8231798 DOI: 10.3390/genes12060913] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/31/2021] [Accepted: 06/10/2021] [Indexed: 12/19/2022] Open
Abstract
Formaldehyde (FA) is a highly reactive substance that is ubiquitous in the environment and is usually considered as a pollutant. In the human body, FA is a product of various metabolic pathways and participates in one-carbon cycle, which provides carbon for the synthesis and modification of bio-compounds, such as DNA, RNA, and amino acids. Endogenous FA plays a role in epigenetic regulation, especially in the methylation and demethylation of DNA, histones, and RNA. Recently, epigenetic alterations associated with FA dysmetabolism have been considered as one of the important features in age-related cognitive impairment (ARCI), suggesting the potential of using FA as a diagnostic biomarker of ARCI. Notably, FA plays multifaceted roles, and, at certain concentrations, it promotes cell proliferation, enhances memory formation, and elongates life span, effects that could also be involved in the aetiology of ARCI. Further investigation of and the regulation of the epigenetics landscape may provide new insights about the aetiology of ARCI and provide novel therapeutic targets.
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Affiliation(s)
- Ting Li
- Bayannur Hospital, Bayannur 015000, China;
| | - Yan Wei
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; (Y.W.); (L.M.); (J.M.)
| | - Meihua Qu
- Translational Medical Center, Weifang Second People’s Hospital, The Second Affiliated Hospital of Weifang Medical University, Weifang 261041, China;
| | - Lixian Mou
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; (Y.W.); (L.M.); (J.M.)
| | - Junye Miao
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; (Y.W.); (L.M.); (J.M.)
| | - Mengqi Xi
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China; (M.X.); (Y.L.)
| | - Ying Liu
- School of Life Sciences, Beijing University of Chinese Medicine, Beijing 102488, China; (M.X.); (Y.L.)
| | - Rongqiao He
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China; (Y.W.); (L.M.); (J.M.)
- Correspondence:
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3
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Tissue-specific epigenetic inheritance after paternal heat exposure in male wild guinea pigs. Mamm Genome 2020; 31:157-169. [PMID: 32285146 PMCID: PMC7369130 DOI: 10.1007/s00335-020-09832-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 03/19/2020] [Indexed: 12/28/2022]
Abstract
External temperature change has been shown to modify epigenetic patterns, such as DNA methylation, which regulates gene expression. DNA methylation is heritable, and as such provides a mechanism to convey environmental information to subsequent generations. Studies on epigenetic response to temperature increase are still scarce in wild mammals, even more so studies that compare tissue-specific epigenetic responses. Here, we aim to address differential epigenetic responses on a gene and gene pathway level in two organs, liver and testis. We chose these organs, because the liver is the main metabolic and thermoregulation organ, and epigenetic modifications in testis are potentially transmitted to the F2 generation. We focused on the transmission of DNA methylation changes to naive male offspring after paternal exposure to an ambient temperature increase of 10 °C, and investigated differential methylated regions of sons sired before and after the paternal exposure using Reduced Representation Bisulfite Sequencing. We detected both a highly tissue-specific epigenetic response, reflected in genes involved in organ-specific metabolic pathways, and a more general regulation of single genes epigenetically modified in both organs. We conclude that genomes are context-specifically differentially epigenetically regulated in response to temperature increase. These findings emphasize the epigenetic relevance in cell differentiation, which is essential for the specific function(s) of complex organs, and is represented in a diverse molecular regulation of genes and gene pathways. The results also emphasize the paternal contribution to adaptive processes.
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Bulić-Jakuš F, Vlahović M, Jurić-Lekić G, Crnek-Kunstelj V, Šerman D. Gastrulating Rat Embryo in a Serum-free Culture Model: Changes of Development Caused by Teratogen 5-Azacytidine. Altern Lab Anim 2019; 27:925-33. [DOI: 10.1177/026119299902700601] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Floriana Bulić-Jakuš
- Department of Biology, Medical Faculty, University of Zagreb, Salata 3, 10000 Zagreb, Croatia
| | - Maja Vlahović
- Department of Biology, Medical Faculty, University of Zagreb, Salata 3, 10000 Zagreb, Croatia
| | - Gordana Jurić-Lekić
- Department of Histology and Embryology, Medical Faculty, University of Zagreb, 10000 Zagreb, Croatia
| | - Vesna Crnek-Kunstelj
- Department of Biology, Medical Faculty, University of Zagreb, Salata 3, 10000 Zagreb, Croatia
| | - Draško Šerman
- Department of Biology, Medical Faculty, University of Zagreb, Salata 3, 10000 Zagreb, Croatia
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5
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Weyrich A, Jeschek M, Schrapers KT, Lenz D, Chung TH, Rübensam K, Yasar S, Schneemann M, Ortmann S, Jewgenow K, Fickel J. Diet changes alter paternally inherited epigenetic pattern in male Wild guinea pigs. ENVIRONMENTAL EPIGENETICS 2018; 4:dvy011. [PMID: 29992049 PMCID: PMC6031029 DOI: 10.1093/eep/dvy011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/19/2018] [Accepted: 04/06/2018] [Indexed: 05/14/2023]
Abstract
Epigenetic modifications, of which DNA methylation is the most stable, are a mechanism conveying environmental information to subsequent generations via parental germ lines. The paternal contribution to adaptive processes in the offspring might be crucial, but has been widely neglected in comparison to the maternal one. To address the paternal impact on the offspring's adaptability to changes in diet composition, we investigated if low protein diet (LPD) in F0 males caused epigenetic alterations in their subsequently sired sons. We therefore fed F0 male Wild guinea pigs with a diet lowered in protein content (LPD) and investigated DNA methylation in sons sired before and after their father's LPD treatment in both, liver and testis tissues. Our results point to a 'heritable epigenetic response' of the sons to the fathers' dietary change. Because we detected methylation changes also in the testis tissue, they are likely to be transmitted to the F2 generation. Gene-network analyses of differentially methylated genes in liver identified main metabolic pathways indicating a metabolic reprogramming ('metabolic shift'). Epigenetic mechanisms, allowing an immediate and inherited adaptation may thus be important for the survival of species in the context of a persistently changing environment, such as climate change.
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Affiliation(s)
- A Weyrich
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - M Jeschek
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
- Berlin Center for Genomics in Biodiversity Research, Koenigin-Luise-Street 6-8, 14195 Berlin, Germany
| | - K T Schrapers
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - D Lenz
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - T H Chung
- Zymoresearch, EpiQuest, 17062 Murphy Avenue, Irvine, CA 92614, USA
| | - K Rübensam
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - S Yasar
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - M Schneemann
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - S Ortmann
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - K Jewgenow
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
| | - J Fickel
- Leibniz-Institute for Zoo and Wildlife Research (IZW), Alfred-Kowalke-Street 17, D-10315 Berlin, Germany
- Institute for Biochemistry and Biology, Potsdam University, Karl-Liebknecht-Street 24-25, 14476 Potsdam, Germany
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Liu M, Zhao J, Chen K, Bian X, Wang C, Shi Y, Wang JM. G protein-coupled receptor FPR1 as a pharmacologic target in inflammation and human glioblastoma. Int Immunopharmacol 2012; 14:283-8. [PMID: 22863814 PMCID: PMC3547636 DOI: 10.1016/j.intimp.2012.07.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 07/23/2012] [Indexed: 11/30/2022]
Abstract
Formylpeptide receptor1 (FPR1) is a G protein-coupled receptor (GPCR) originally identified in phagocytic leucocytes and mediates cell chemotaxis and activation in response to bacterial formylated chemotactic peptides. However, FPR1 also participates in a signal relay which regulates the infiltration of phagocytes, in particular neutrophils, to inflammatory sites in response to tissue-derived chemoattractant ligands. In addition to participating in innate immune responses, recently, FPR1 has been shown to be expressed by highly malignant glioblastoma (GBM) cells. Upon activation by an endogenous agonist Annexin 1 (Anx A1) released by necrotic glioma cells, FPR1 transactivates the receptor for epithelial growth factor (EGFR) and consequently to promote glioma cell chemotaxis, invasion, growth and production of angiogenic factors. The observations demonstrate that FPR1, as a multifunctional GPCR with pattern recognition properties, is not only involved in innate immune responses but also in the progression of GBM. Thus, FPR1 is an immunopharmacologic target for development of novel therapies.
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Affiliation(s)
- Mingyong Liu
- Department of Spine Surgery, Daping Hospital, Third Military Medical University, Chongqing 400042, China
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Jianhua Zhao
- Department of Spine Surgery, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Keqiang Chen
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Xiuwu Bian
- Institute of Pathology and Southwest Cancer Center, Third Military Medical University, Chongqing 400038, China
| | - Chunyan Wang
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
- Xuzhou Yes Biotech Laboratories Ltd. Xuzhou, Jiangsu, 221004, China
| | - Ying Shi
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
- College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Ji Ming Wang
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
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7
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Munshi A, Duvvuri S. Genomic imprinting - the story of the other half and the conflicts of silencing. J Genet Genomics 2009; 34:93-103. [PMID: 17469781 DOI: 10.1016/s1673-8527(07)60010-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 09/26/2006] [Indexed: 11/20/2022]
Abstract
Genomic imprinting is an epigenetic mechanism that produces functional differences between the paternal and maternal genomes and plays an essential role in mammalian development and growth. There are a number of genes in our genomes that are subject to genomic imprinting where one parent's copy of the gene is expressed while the other is silent. Silencing of one allele predetermines that any function ascribed to that gene are now dependant on the single active copy. Possession of only a single active allele can lead to deleterious health consequences in humans. If imprinted genes are crucial in mammalian development, one would also expect mutations in these genes to cause diseases. Since imprinting is an epigenetic mechanism, mistakes in maintaining epigenetic mark also cause imprinting disorders. Here we in this review focus on the current understanding of this unique genetic mechanism more than two decades after the first description of the imprinting phenomenon was given by McGrath and Solter. Although the possible molecular mechanisms by which imprinting is imposed and maintained are being identified, we have a long way to go in understanding the molecular mechanisms that regulate the expression of these oddly behaving genes, the function of imprinting and the evolution. Post genomic technologies might ultimately lead to a better understanding of the 'imprinting effects'.
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Affiliation(s)
- Anjana Munshi
- Department of Genetics, Shadan PG Centre for Biosciences, Khairtabad Hyderabad 500016, India.
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8
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Huang J, Chen K, Huang J, Gong W, Dunlop NM, Howard OMZ, Bian X, Gao Y, Wang JM. Regulation of the leucocyte chemoattractant receptor FPR in glioblastoma cells by cell differentiation. Carcinogenesis 2008; 30:348-55. [PMID: 19037090 DOI: 10.1093/carcin/bgn266] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The G protein-coupled formylpeptide receptor (FPR), known to mediate phagocytic leucocyte chemotaxis in response to bacterial- and host-derived agonists, was expressed by tumor cells in specimens of surgically removed more highly malignant human gliomas. In human glioblastoma cell lines, FPR activation increased cell motility, tumorigenicity and production of angiogenic factors. In studies of the mechanistic basis for the selective expression of FPR in more highly malignant gliomas, we found that the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (Aza), while promoting the differentiation of human glioblastoma cells, downregulated FPR expression. Aza also reduced the global methylation levels in glioblastoma cells and activated the pathway of p53 tumor suppressor. Methylation-specific polymerase chain reaction revealed that Aza treatment of tumor cells reduced the methylation of p53 promoter, which was accompanied by increased expression of p53 gene and protein. In addition, overexpression of p53 in glioblastoma cells mimicked the effect of Aza treatment as shown by increased cell differentiation but reduction in FPR expression, the capacity of tumor sphere formation in soft agar and tumorigenesis in nude mice. Furthermore, Aza treatment or overexpression of the wild-type p53 in glioblastoma cells increased the binding of p53 to FPR promoter region shown by chromatin immunoprecipitation. These results indicate that increased methylation of p53 gene retains human glioblastoma cells at a more poorly differentiated phase associated with the aberrant expression of FPR as a tumor-promoting cell surface receptor.
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Affiliation(s)
- Jian Huang
- Laboratory of Molecular Immunoregulation, Cancer and Inflammation Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
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9
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Wren JD, Garner HR. Data-mining analysis suggests an epigenetic pathogenesis for type 2 diabetes. J Biomed Biotechnol 2006; 2005:104-12. [PMID: 16046815 PMCID: PMC1184044 DOI: 10.1155/jbb.2005.104] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The etiological origin of type 2 diabetes mellitus (T2DM) has long
been controversial. The body of literature related to T2DM is vast
and varied in focus, making a broad epidemiological perspective
difficult, if not impossible. A data-mining approach was used to
analyze all electronically available scientific literature, over
12 million Medline records, for “objects” such as genes,
diseases, phenotypes, and chemical compounds linked to other
objects within the T2DM literature but were not themselves within
the T2DM literature. The goal of this analysis was to conduct a
comprehensive survey to identify novel factors implicated in the
pathology of T2DM by statistically evaluating mutually shared
associations. Surprisingly, epigenetic factors were among the
highest statistical scores in this analysis, strongly implicating
epigenetic changes within the body as causal factors in the
pathogenesis of T2DM. Further analysis implicates adipocytes as
the potential tissue of origin, and cytokines or cytokine-like
genes as the dysregulated factor(s) responsible for the T2DM
phenotype. The analysis provides a wealth of literature supporting
this hypothesis, which—if true—represents an important
paradigm shift for researchers studying the pathogenesis of T2DM.
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Affiliation(s)
- Jonathan D Wren
- Advanced Center for Genome Technology, Department of Botany and Microbiology, The University of Oklahoma, 101 David L Boren Blvd, Rm 2025, Norman, OK 73019, USA.
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10
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Schatz P, Dietrich D, Schuster M. Rapid analysis of CpG methylation patterns using RNase T1 cleavage and MALDI-TOF. Nucleic Acids Res 2004; 32:e167. [PMID: 15576674 PMCID: PMC535694 DOI: 10.1093/nar/gnh165] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Here, we introduce a method for the fast and accurate analysis of DNA methylation based on bisulfite-treated DNA. The target region is PCR amplified using a T7 RNA polymerase promoter-tagged primer. A subsequent in vitro transcription leads to a transcript which contains guanosine residues only at sites that contained methylated cytosines before bisulfite treatment. In a single tube reaction using guanosine-specific cleavage by RNase T1, a specific pattern of RNA fragments is formed. This pattern directly represents the methylation state of the sample DNA and is analyzed using matrix-assisted laser desorption ionization time-of-flight technology. This method was successfully applied to the analysis of artificially methylated and unmethylated DNA, mixtures thereof and colon DNA samples. The applicability for the analysis of both PCR products and cloned PCR products is demonstrated. The observed methylation patterns were confirmed by bisulfite sequencing.
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Affiliation(s)
- Philipp Schatz
- Epigenomics AG, Science Department, Kleine Präsidentenstrasse 1, D-10178 Berlin, Germany
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11
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Finnell RH, Junker WM, Wadman LK, Cabrera RM. Gene expression profiling within the developing neural tube. Neurochem Res 2002; 27:1165-80. [PMID: 12462415 DOI: 10.1023/a:1020977409850] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The developing mammalian nervous system is subject to devastating congenital malformations with clinical significance that extends into the billions of health care dollars annually worldwide. Neural tube defects (NTDs) are among the most common of all human congenital defects, yet their etiology remains poorly understood. This is largely due to the complexity of the genetic factors regulating the intricate events involved in neurulation. Using mouse model systems and the application of modern molecular biological technologies, we have recently gained a greater appreciation for the factors that not only regulate normal neural tube closure (NTC), but those genetic factors that predispose an embryo to significant birth defects such as anencephaly or spina bifida. We have selected prominent murine mutants, both spontaneous and genetically modified, as well as the use of teratogenic agents, to examine the impact of altering the normal pattern of gene expression in the developing neural tube.
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Affiliation(s)
- Richard H Finnell
- Institute of Biosciences and Technology, Texas A & M University System Health Science Center, Houston, TX 77030-3303, USA.
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12
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Branch S, Henry-Sam G. Altered hox gene expression and cellular pathogenesis of 5-aza-2'-deoxycytidine-induced murine hindlimb dysmorphogenesis. Toxicol Pathol 2001; 29:501-6. [PMID: 11695566 DOI: 10.1080/019262301317226294] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The DNA demethylating agent, 5-aza-2'-deoxycytidine (d-AZA), elicits temporally related morphological defects and altered gene expression in mouse hindlimbs. Segmental formation of limb regions (stylopod, zeugopod. and autopod) is partially dependent on Hox gene activation. The objective of this study was to understand the role of altered expression of key hox genes in the early pathogenesis of d-AZA-induced hindlimb defects in mice. Semiquantitative RT-PCR was used to analyze hox gene expression (Hox C-11 and Hox A and D homologs, paralogs 9-13). Untreated and treated fore and hindlimb buds were collected 12 and 24 hours after IP injection (1 mg/kg) of d-AZA at 9 am on gestational (GD) 10 and processed for RT-PCR. Additional pregnant mice were treated similarly and whole embryos collected 12 and 24 hours posttreatment and processed for histopathological analysis. No changes in hox gene expression were detected in the forelimb tissue. There was a 2-fold down-regulation of hoxA-11 and C-11 in the 12-hour hindlimb bud tissue. No changes in the HoxD series were detected in the hindlimb bud tissue. The 12- and 24-hour untreated mice exhibited some of the morphological features consistent with physiological apoptosis. Most tissues of the treated mice exhibited cellular changes consistent with cell death associated with the cytotoxicity of the compound. The data reported supports the hypothesis that altered gene expression and not cytotoxicity alone is associated with d-AZA-induced hindlimb dysmorphogenesis.
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Affiliation(s)
- S Branch
- North Carolina State University, Department of Environmental and Molecular Toxicology, Raleigh 27695, USA.
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13
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Abstract
Reciprocal outcrosses and backcrosses were made between strains of mice with different susceptibilities to valproic acid (VPA) teratogenicity. Relatively resistant C57BL/6J (C) and more susceptible SWV (S) strains of mice produced F1 hybrids in which the female parent was C and the male parent was S (CS-F1) as well as the reciprocal with S dams and C sires (SC-F1). Each was backcrossed to each strain, producing 8 types of backcross matings: CS x C, SC x C, CS x S, SC x S; C x CS, C x SC, S x CS, S x SC (for all matings dams are listed first). At 8d:12 +/- 5h of gestation, a teratogenic dose, 600 mg/kg, of aqueous VPA was injected ip into the dams. Fetuses were examined on gestation day (gd) 18 for abnormality, mortality, litter size, and weight. Genomic imprinting (imprinting) is a phenomenon at least in part involving hyper- or hypomethylation of bases in DNA, which is believed to determine whether or not the imprinted gene will be expressed. Imprinting has been reported to occur differentially in the male and female for a number of gene loci. Thus, in crosses between strains with differing susceptibility to VPA, if imprinting is occurring, the susceptibility of a fetus might be predicted to be disproportionately influenced by susceptibility of its grandparents. Significant differences in frequency (%) of occurrence of exencephaly in progeny of all backcrosses with F1 dams consistent with those expected for imprinting were found in the present study (CS-F1x C = 21.8 +/- 3.9%, SC-F1x C = 10.8 +/- 3.2%, P < 0.03; CS-F1x S = 14.8 +/- 3.1%, SC-F1x S = 6.3 +/- 2.3%, P < 0.03). SWV dams revealed the same pattern (S x SC-F1 = 50.0 +/- 8.3%, S x CS-F1 = 37.1 +/- 4.7%, P < 0.04). Differences in prenatal mortality also consistent with genomic imprinting occurred in backcrosses with pure-line SWV dams (S x SC = 64.4 +/- 8.0%, S x CS = 30.5 +/- 4.5%, P < 0.001). Fetal weight was reduced in a manner consistent with imprinting in backcrosses involving SWV (S x SC = 0.50 +/- 0.18 g, S x CS = 0.96 +/- 0.05, P < 0.01). Three of four of the parameters investigated showed differences in some of the backcrosses of reciprocal F1's consistent with those expected if genomic imprinting were occurring.
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Affiliation(s)
- S L Beck
- Biology Department, DePaul University, 2325 N Clifton Avenue, 60614, Chicago, IL, USA.
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14
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Grunau C, Schattevoy R, Mache N, Rosenthal A. MethTools--a toolbox to visualize and analyze DNA methylation data. Nucleic Acids Res 2000; 28:1053-8. [PMID: 10666443 PMCID: PMC102603 DOI: 10.1093/nar/28.5.1053] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Bisulfite Genomic Sequencing technique has found wide acceptance for the generation of DNA-methylation maps with single-base resolution. The method is based on the selective deamination of cytosine to uracil (and subsequent conversion to thymine via PCR), whereas 5-methylcytosine residues remain unchanged. Methylation maps are created by the comparison of bisulfite converted sequences with the untreated genomic sequence. 'MethTools' is a collection of software tools that replaces the time-consuming manual comparison process, generates graphical outputs of methylation patterns and methyl-ation density, estimates the systematic error of the experiment and searches for conserved methylated nucleotide patterns. The programs are written in Perl 5 and C, and the source code can be downloaded. All tools run independently but the programs are interfaced. Thus, a script can perform the entire analysis procedure automatically. In addition, a web-based remote analysis service is offered. Both the source code and the remote analysis are available at http://genome.imb-jena.de/methtools/
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Affiliation(s)
- C Grunau
- Department of Genome Analysis, Institute for Molecular Biotechnology, Beutenbergstrasse 11, D-07745 Jena, Germany
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Amado L, Abranches R, Neves N, Viegas W. Development-dependent inheritance of 5-azacytidine-induced epimutations in triticale: analysis of rDNA expression patterns. Chromosome Res 1997; 5:445-50. [PMID: 9421260 DOI: 10.1023/a:1018460828720] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Genomic imprinting of rye origin rDNA sequences in triticale is modulated by DNA methylation responsible for ontogenic expression patterns of those sequences. Considering the dynamic nature of these phenomena, we evaluated the influence of plant development on the inheritance of modified rye rDNA expression patterns. DNA hypomethylation was induced in triticale by 5-azacytidine (5AC) treatments at distinct developmental stages of M1 plants, and expression patterns were analysed in M2. The activity of rye origin rRNA genes in progeny of untreated and 5AC-treated plants was evaluated by silver staining in meristematic root tip cells and in meiocytes at diplotene. In the progeny of 5AC-treated plants, a significant increase in rye rDNA expression was observed, contrasting with the residual activity in untreated plants. Significant differential effects of 5AC treatments were observed in M2 plants and correlated with the M1 plant developmental stage in which DNA hypomethylation was induced. Hypotheses to explain the origin of those differences are discussed here.
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Affiliation(s)
- L Amado
- Secção de Genética do Departamento de Botânica e Engenharia Biológica, Instituto Superior de Agronomia, Lisboa, Portugal.
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16
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Branch S, Francis BM, Brownie CF, Chernoff N. Teratogenic effects of the demethylating agent 5-aza-2'-deoxycytidine in the Swiss Webster mouse. Toxicology 1996; 112:37-43. [PMID: 8792847 DOI: 10.1016/0300-483x(96)88183-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
5-Aza-2'-deoxycytidine (d-AZA) replaces cytidine in DNA thereby altering gene expression by passively removing methyl groups. This study determined the temporal patterns of morphological defects induced by d-AZA in mice. The dosages (0, 0.3, or 1.0 mg/kg) were administered by a single i.p. injection on gestational days (GD) 8, 9, 10, or 11. Mice were killed on GD 17 and fetal skeletons examined. The 1.0 mg/kg dose elicited characteristic defects for each treatment day: GD 8, supernumerary ribs, (significantly above background), fused vertebrae and ribs; GD 9, cleft palate and vertebral variations; GD 10, hind limb defects (especially phocomelia); GD 11, digital defects of fore and hindlimbs. The known demethylating ability of d-AZA coupled with the induction of longbone defects only in the hindlimbs suggests that d-AZA may act by disrupting specific hindlimb gene function through DNA hypomethylation.
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Affiliation(s)
- S Branch
- North Carolina State University, Department of Toxicology, Raleigh 27695, USA
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17
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Penkov LI, Platonov ES, Mironova OV, Konyukhov BV. Effects of 5-azacytidine on the development of parthenogenetic mouse embryos. Dev Growth Differ 1996. [DOI: 10.1046/j.1440-169x.1996.t01-2-00005.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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18
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Clinical development plan: Folic acid. J Cell Biochem 1996. [DOI: 10.1002/jcb.240630708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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19
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Chatkupt S, Antonowicz M, Johnson WG. Parents do matter: genomic imprinting and parental sex effects in neurological disorders. J Neurol Sci 1995; 130:1-10. [PMID: 7650524 DOI: 10.1016/0022-510x(94)00284-u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Genomic imprinting is a recently recognized phenomenon of differential expression of genetic material depending upon whether the genetic material has come from the male or female parent. This process of differential phenotypic expression involves mammalian development both in the normal and abnormal situations, resulting in parental sex effects. However, some parental sex effects may be due to other mechanisms such as mitochondrial inheritance. In the following article, evidence for genomic imprinting in experimental animals and in diseases are summarized. Relevant human neurological disorders manifesting parental sex effects discussed here include myotonic dystrophy, Huntington's disease, fragile X syndrome, spinocerebellar ataxia type 1, and neurofibromatosis type 1 and 2. A possible mechanism of imprinting involves the processes of methylation imprint and replication imprint. The knowledge of imprinting is helpful in clinical practice particularly in the areas of genetic counseling, prenatal diagnosis, and possible future gene therapy.
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Affiliation(s)
- S Chatkupt
- Department of Neurosciences, UMDNJ-New Jersey Medical School, Newark 07103, USA
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20
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Ruiz-Herrera J, Ruiz-Medrano R, Domínguez A. Selective inhibition of cytosine-DNA methylases by polyamines. FEBS Lett 1995; 357:192-6. [PMID: 7805889 DOI: 10.1016/0014-5793(94)01360-d] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have advanced the hypothesis that polyamines affect DNA methylation and thus promote the expression of developmentally controlled genes. We demonstrate that the activity of cytosine-DNA methyltransferases HpaII, HhaI, HaeIII and SssI is inhibited by physiological concentrations of polyamines. On the other hand, activity of the adenine-DNA methyltransferase EcoRI, and restriction enzymes HpaII, HhaI, HaeIII and EcoRI, is insensitive to polyamine concentrations up to 40 mM. Our results indicate that the effect of polyamines on cytosine-DNA methyltransferases is rather selective and suggest a possible mode of action in vivo.
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Affiliation(s)
- J Ruiz-Herrera
- Departmento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, Gto., Mexico
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21
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Thomas DJ. Arsenic toxicity in humans: Research problems and prospects. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 1994; 16:107-111. [PMID: 24197204 DOI: 10.1007/bf01747906] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/10/1993] [Indexed: 06/02/2023]
Abstract
The disposition and toxicity of the metalloid, arsenic, is affected by its oxidation state and on the extent to which it is converted to methylated species. Given that these chemical modifications influence the fate and action of arsenic, new research efforts should be directed both towards elucidating the molecular processes involved in the metabolism of arsenic and in characterising interindividual variation in capacity for processes such as the methylation of arsenic. This information will contribute to a better understanding of the mechanisms of arsenic toxicity and carcinogenicity and to a better assessment of the hazards associated with chronic exposure to this agent.
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Affiliation(s)
- D J Thomas
- Pharmacokinetics Branch, Environmental Toxicology Division, Health Effects Research Laboratory, US Environmental Protection Agency, 27711, Research Triangle Park, North Carolina, USA
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22
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Rogers JM, Francis BM, Sulik KK, Alles AJ, Massaro EJ, Zucker RM, Elstein KH, Rosen MB, Chernoff N. Cell death and cell cycle perturbation in the developmental toxicity of the demethylating agent, 5-aza-2'-deoxycytidine. TERATOLOGY 1994; 50:332-9. [PMID: 7536356 DOI: 10.1002/tera.1420500504] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
DNA methylation is a probable mechanism for regulating gene expression, and alterations in methylation may significantly affect embryonic development. We administered the cytidine analogue 5-aza-2'-deoxycytidine (dAZA), a specific and potent demethylator of DNA, to pregnant mice to determine its teratogenicity and effects on embryonic cell death and cell cycle. Groups of females were dosed intraperitoneally on gestation day 10 with doses of 0.05-3 mg/kg dAZA and killed at 4, 8, or 28 hr later. Two embryos per litter were immediately stained with Nile blue sulfate (NBS) to identify areas of cell death; the remaining embryos were frozen and stored for subsequent flow cytometric (FCM) analysis of the cellular DNA synthetic cycle in limb buds. A dose-related accumulation of cells in the S and G2/M phases was observed at 4 and 8 hr after maternal dosing. S-phase accumulation was the most sensitive indicator of effect; a dose-related increase in the percentage of hindlimb bud cells in S-phase was evident at all dosages 4 hr after maternal dosing. By 28 hr postdosing, a normal cell cycle phase distribution was observed at doses of < 0.3 mg/kg. However, cell cycle perturbations persisted at higher dosages. NBS staining demonstrated increased cell death in areas of rapid cell division, indicative of replication-associated cytotoxicity, at doses of > or = 0.1 mg/kg. Observation of litters from additional dams killed at term revealed that at dosages of > or = 0.3 mg/kg, cleft palate and hindlimb defects were significantly elevated. In addition, above 0.3 mg/kg, fetal weight was significantly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J M Rogers
- Developmental Toxicology Division, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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23
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Juchau MR. Chemical teratogenesis. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1993; 41:9-50. [PMID: 8108564 DOI: 10.1007/978-3-0348-7150-1_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This review has briefly summarized what is currently known concerning the mechanisms whereby several groups of chemicals regarded as "recognized" human teratogens elicit their respective teratogenic effects. It is evident that the extent of our understanding of mechanisms for individual chemicals varies dramatically from that of a reasonably good understanding for methotrexate and other folic acid antagonists to that of virtually no understanding for the most widely recognized human teratogen, thalidomide. Even with methotrexate, however, much remains to be learned pertaining to mechanisms--i.e., the critical links in the chain of events between dihydrofolate reductase inhibition and the manifestation of specific abnormalities. Nevertheless, we can take some comfort in being able to say that we understand the primary causative mechanism. For thalidomide, as well as several others the chemical represents both a shame and a challenge--a challenge that should be addressed with our most serious efforts.
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Affiliation(s)
- M R Juchau
- Department of Pharmacology, School of Medicine SJ-30, University of Washington, Seattle 98195
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24
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Lea MA. Action of exogenous differentiating agents on gene expression in cancer cells. Crit Rev Oncol Hematol 1992; 13:189-214. [PMID: 1476653 DOI: 10.1016/1040-8428(92)90090-d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- M A Lea
- Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey Medical School, Newark 07103
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25
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Münzel PA, Pfohl-Leszkowicz A, Röhrdanz E, Keith G, Dirheimer G, Bock KW. Site-specific hypomethylation of c-myc protooncogene in liver nodules and inhibition of DNA methylation by N-nitrosomorpholine. Biochem Pharmacol 1991; 42:365-71. [PMID: 1859451 DOI: 10.1016/0006-2952(91)90724-j] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The protooncogene c-myc was investigated in N-nitrosomorpholine-induced rat liver nodules to elucidate the role of altered DNA methylation in chemical carcinogenesis. Furthermore, Micrococcus luteus DNA and chicken erythrocyte DNA were modified in vitro by reactive metabolites of N-nitrosomorpholine, generated by P450-dependent monooxygenases. The modified DNAs were less methylated in vitro than control DNAs by DNA-(cytosine-5)-methyltransferase (DNA methylase). The DNA methylase assay and 32P-postlabeling analysis revealed lowered levels of DNA methylation in nodular DNA. In nodular tissue, c-myc messenger RNA levels were found to be increased compared to normal liver. DNA methylation analysis using the restriction endonucleases HpaII/MspI indicated hypomethylation in the first intron of c-myc DNA in liver nodules. The results suggest that genotoxic lesions may cause stably inherited, aberrant DNA methylation patterns which may be responsible for site-specific hypomethylation of the c-myc protooncogene in liver nodules.
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Affiliation(s)
- P A Münzel
- Institute of Toxicology, University of Tübingen, Federal Republic of Germany
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26
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Inamdar NM, Ehrlich KC, Ehrlich M. CpG methylation inhibits binding of several sequence-specific DNA-binding proteins from pea, wheat, soybean and cauliflower. PLANT MOLECULAR BIOLOGY 1991; 17:111-23. [PMID: 1831056 DOI: 10.1007/bf00036811] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
To elucidate how methylation of specific sites in plant DNA might control transcription, we examined the effect of DNA methylation at CpG sequences on the binding of plant nuclear factors to an oligonucleotide duplex containing the consensus sequence for mammalian CREB (cAMP response element binding protein). CREB is part of the ATF (activating transcription factor) family of mammalian proteins specifically binding to 5'-TGACGTCA-3' and related sequences. Proteins recognizing the CREB-specific ligand were identified in nuclear extracts of pea seeds, wheat germ, cauliflower, and soybean leaves using electrophoretic mobility shift assays. Cytosine methylation inhibited binding of this protein in all these extracts, and so this sequence-specific DNA-binding activity is referred to as methylation-inhibited binding protein 1 (MIB-1). Sites somewhat similar to that of the CREB ligand are found in the upstream regions of a wheat histone H3 gene and tomato and pea ribulose 1,5-bisphosphate carboxylase genes. These sites were bound preferentially by distinct proteins that may be related to the previously described plant proteins HBP-1, HSBF, ASF-1, or GBF. Methylation of cytosine residues at these sites and at a site for MIB-1 located upstream of a soybean proline-rich protein gene also reduced specific binding with all the nuclear extracts tested. Similarly, substitution of the central CpG dinucleotide with TpG decreased binding.
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Affiliation(s)
- N M Inamdar
- Department of Biochemistry, Tulane Medical School, New Orleans, LA 70112
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27
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Thomas DJ, Angle CR, Swanson SA. Effect of 5-azacytidine on metallothionein inducibility and sensitivity to lethality of cadmium in rat osteosarcoma (ROS 17/2.8) cells. Toxicology 1990; 65:169-78. [PMID: 1703334 DOI: 10.1016/0300-483x(90)90087-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
ROS 17/2.8 cells, a cloned rat osteoblastic osteosarcoma cell line, were found to be extremely sensitive to the lethal effects of cadmium and to synthesize little, if any, metallothionein in response to cadmium exposure. Culture of cells for 24 h in the presence of 1 microM 5-azacytidine, a cytidine analog, increased the inducibility of metallothionein by cadmium and significantly reduced (P less than 0.001) cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytotoxicity. Anion exchange chromatographic analysis of cadmium binding to low molecular mass cytosolic proteins showed that cells treated with cadmium and 5-azacytidine expressed at least 2 isoforms of metallothionein. One isoform of metallothionein with a low affinity for cadmium was constitutively expressed by these cells. The association of poor inducibility of metallothionein by cadmium with extreme sensitivity of cells to cadmium emphasizes the role of this protein in the cellular response to this toxic metal. The modulation of metallothionein inducibility and sensitivity to cadmium by 5-azacytidine treatment suggest that metallothionein gene structure and regulation are altered in ROS 17/2.8 cells.
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Affiliation(s)
- D J Thomas
- Department of Pediatrics, College of Medicine, University of Nebraska Medical Center, Omaha 68198
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28
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Hammond WG, Yellin A, Gabriel A, Paladugu RR, Azumi N, Hill LR, Benfield JR. Effects of 5-azacytidine in Syrian golden hamsters: toxicity, tumorigenicity, and differential modulation of bronchial carcinogenesis. Exp Mol Pathol 1990; 53:34-51. [PMID: 1698660 DOI: 10.1016/0014-4800(90)90022-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
5-Azacytidine (AZC) was studied in a lung cancer model in outbred and syngeneic (F1D) hamsters wherein benzol[a]pyrene (BP) from sustained release implants (SRI) induces preneoplastic mucosal changes which progress to bronchogenic cancer. In pilot studies to evaluate AZC toxicity, a dose schedule of 5 mg/kg biweekly was found suitable and was then used for long-term administration in all subsequent studies. Three groups of outbred hamsters were studied: BP SRi alone (n = 60), BP SRI + AZC (n = 60), and AZC alone (n = 54). AZC treatment was begun 3-5 days after SRI placement. Sixty-one days after the start of the experiment, seven or eight hamsters were sacrificed from each group. Later sacrifices were at 3-week intervals in groups receiving BP SRI and at 6-week intervals in the AZC only group. Four groups of F1D syngeneic hamsters were studied: BP SRI alone (n = 50); BP + AZC starting 3-5 days after SRI placement and continuing until death (n = 52); BP + AZC from 3 to 5 days until 75 days after SRI placement (n = 49); BP + AZC starting 80 days after SRI placement and continuing until death (n = 52). Hamsters (n = 9-14) from each group were sacrificed at 120, 150, 180, and 220 days after SRI implantation. AZC alone was not carcinogenic under these conditions. Both outbred and F1D hamsters treated with early or continuous AZC had slower rates of neoplastic change from BP SRI than did animals receiving BP SRIs alone or BP + late AZC. The incidence of epidermoid cancer were the same for all regimens, but the tumors in those receiving AZC early in carcinogenesis were smaller than in those receiving late or no AZC. The incidences of nonepidermoid cancer were lower in those receiving AZC during early carcinogenesis, and larger tumors were noted in the absence of AZC. Thus, within the study period in this unique hamster lung cancer model, AZC given early in carcinogenesis inhibited only the later (promotional) phase of BP epidermoid carcinogenesis, but inhibited all phases of nonsquamous cancer development induced by BP. This differential modulation of bronchial carcinogenesis, which occurs from AZC given during preneoplastic stages, may prove useful for delineating molecular mechanisms underlying specific phenotypic types of bronchogenic cancers.
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Affiliation(s)
- W G Hammond
- Department of Thoracic Surgery, City of Hope National Medical Center, Duarte, California 91010
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