TY - JOUR A1 - Becker, Nils A1 - Kucharski, Robert A1 - Rössler, Wolfgang A1 - Maleszka, Ryszard T1 - Age‐dependent transcriptional and epigenomic responses to light exposure in the honey bee brain JF - FEBS Open Bio N2 - Light is a powerful environmental stimulus of special importance in social honey bees that undergo a behavioral transition from in-hive to outdoor foraging duties. Our previous work has shown that light exposure induces structural neuronal plasticity in the mushroom bodies (MBs), a brain center implicated in processing inputs from sensory modalities. Here, we extended these analyses to the molecular level to unravel light-induced transcriptomic and epigenomic changes in the honey bee brain. We have compared gene expression in brain compartments of 1- and 7-day-old light-exposed honey bees with age-matched dark-kept individuals. We have found a number of differentially expressed genes (DEGs), both novel and conserved, including several genes with reported roles in neuronal plasticity. Most of the DEGs show age-related changes in the amplitude of light-induced expression and are likely to be both developmentally and environmentally regulated. Some of the DEGs are either known to be methylated or are implicated in epigenetic processes suggesting that responses to light exposure are at least partly regulated at the epigenome level. Consistent with this idea light alters the DNA methylation pattern of bgm, one of the DEGs affected by light exposure, and the expression of microRNA miR-932. This confirms the usefulness of our approach to identify candidate genes for neuronal plasticity and provides evidence for the role of epigenetic processes in driving the molecular responses to visual stimulation. KW - DNA methylation KW - insect brain KW - light-induced gene expression KW - microRNA KW - neuronal plasticity Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-147080 VL - 6 IS - 7 ER - TY - JOUR A1 - Carmela Vegliante, Maria A1 - Royo, Cristina A1 - Palomero, Jara A1 - Salaverria, Itziar A1 - Balint, Balazs A1 - Martin-Guerrero, Idoia A1 - Agirre, Xabier A1 - Lujambio, Amaia A1 - Richter, Julia A1 - Xargay-Torrent, Silvia A1 - Bea, Silvia A1 - Hernandez, Luis A1 - Enjuanes, Anna A1 - Jose Calasanz, Maria A1 - Rosenwald, Andreas A1 - Ott, German A1 - Roman-Gomez, Jose A1 - Prosper, Felipe A1 - Esteller, Manel A1 - Jares, Pedro A1 - Siebert, Reiner A1 - Campo, Elias A1 - Martin-Subero, Jose I. A1 - Amador, Virginia T1 - Epigenetic Activation of SOX11 in Lymphoid Neoplasms by Histone Modifications JF - PLoS ONE N2 - Recent studies have shown aberrant expression of SOX11 in various types of aggressive B-cell neoplasms. To elucidate the molecular mechanisms leading to such deregulation, we performed a comprehensive SOX11 gene expression and epigenetic study in stem cells, normal hematopoietic cells and different lymphoid neoplasms. We observed that SOX11 expression is associated with unmethylated DNA and presence of activating histone marks (H3K9/14Ac and H3K4me3) in embryonic stem cells and some aggressive B-cell neoplasms. In contrast, adult stem cells, normal hematopoietic cells and other lymphoid neoplasms do not express SOX11. Such repression was associated with silencing histone marks H3K9me2 and H3K27me3. The SOX11 promoter of non-malignant cells was consistently unmethylated whereas lymphoid neoplasms with silenced SOX11 tended to acquire DNA hypermethylation. SOX11 silencing in cell lines was reversed by the histone deacetylase inhibitor SAHA but not by the DNA methyltransferase inhibitor AZA. These data indicate that, although DNA hypermethylation of SOX11 is frequent in lymphoid neoplasms, it seems to be functionally inert, as SOX11 is already silenced in the hematopoietic system. In contrast, the pathogenic role of SOX11 is associated with its de novo expression in some aggressive lymphoid malignancies, which is mediated by a shift from inactivating to activating histone modifications. KW - Mantle cell lymphoma KW - Defined burkitts lymphoma KW - Transcription-factor KW - Gene-expression KW - High-resolution KW - DNA methylation KW - Nuclear expression KW - Cancer KW - Microarray KW - Survival Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-135325 VL - 6 IS - 6 ER - TY - JOUR A1 - de Nijs, Laurence A1 - Choe, Kyonghwan A1 - Steinbusch, Hellen A1 - Schijns, Olaf E. M. G. A1 - Dings, Jim A1 - van den Hove, Daniel L. A. A1 - Rutten, Bart P. F. A1 - Hoogland, Govert T1 - DNA methyltransferase isoforms expression in the temporal lobe of epilepsy patients with a history of febrile seizures JF - Clinical Epigenetics N2 - Background Temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) is a common pharmaco-resistant epilepsy referred for adult epilepsy surgery. Though associated with prolonged febrile seizures (FS) in childhood, the neurobiological basis for this relationship is not fully understood and currently no preventive or curative therapies are available. DNA methylation, an epigenetic mechanism catalyzed by DNA methyltransferases (DNMTs), potentially plays a pivotal role in epileptogenesis associated with FS. In an attempt to start exploring this notion, the present cross-sectional pilot study investigated whether global DNA methylation levels (5-mC and 5-hmC markers) and DNMT isoforms (DNMT1, DNMT3a1, and DNMT3a2) expression would be different in hippocampal and neocortical tissues between controls and TLE patients with or without a history of FS. Results We found that global DNA methylation levels and DNMT3a2 isoform expression were lower in the hippocampus for all TLE groups when compared to control patients, with a more significant decrease amongst the TLE groups with a history of FS. Interestingly, we showed that DNMT3a1 expression was severely diminished in the hippocampus of TLE patients with a history of FS in comparison with control and other TLE groups. In the neocortex, we found a higher expression of DNMT1 and DNMT3a1 as well as increased levels of global DNA methylation for all TLE patients compared to controls. Conclusion Together, the findings of this descriptive cross-sectional pilot study demonstrated brain region-specific changes in DNMT1 and DNMT3a isoform expression as well as global DNA methylation levels in human TLE with or without a history of FS. They highlighted a specific implication of DNMT3a isoforms in TLE after FS. Therefore, longitudinal studies that aim at targeting DNMT3a isoforms to evaluate the potential causal relationship between FS and TLE or treatment of FS-induced epileptogenesis seem warranted. KW - febrile seizures KW - temporal lobe epilepsy KW - epigenetics KW - DNA methylation KW - DNA methyltransferases Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223636 VL - 11 ER - TY - JOUR A1 - Deeken, Rosalia A1 - Gohlke, Jochen A1 - Scholz, Claus-Juergen A1 - Kneitz, Susanne A1 - Weber, Dana A1 - Fuchs, Joerg A1 - Hedrich, Rainer T1 - DNA Methylation Mediated Control of Gene Expression Is Critical for Development of Crown Gall Tumors JF - PLoS Genetics N2 - Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA–encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA) in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA–mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes regulate gene expression, physiological processes, and the development of crown gall tumors. KW - DNA methylation KW - DNA transcription KW - gene expression KW - oncogenes KW - plant genomics KW - sequence motif analysis KW - arabidopsis thaliana KW - agrobacterium tumefaciens Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96318 ER - TY - JOUR A1 - El Hajj, Nady A1 - Dittrich, Marcus A1 - Böck, Julia A1 - Kraus, Theo F. J. A1 - Nanda, Indrajit A1 - Müller, Tobias A1 - Seidmann, Larissa A1 - Tralau, Tim A1 - Galetzka, Danuta A1 - Schneider, Eberhard A1 - Haaf, Thomas T1 - Epigenetic dysregulation in the developing Down syndrome cortex JF - Epigenetics N2 - Using Illumina 450K arrays, 1.85% of all analyzed CpG sites were significantly hypermethylated and 0.31% hypomethylated in fetal Down syndrome (DS) cortex throughout the genome. The methylation changes on chromosome 21 appeared to be balanced between hypo- and hyper-methylation, whereas, consistent with prior reports, all other chromosomes showed 3-11times more hyper- than hypo-methylated sites. Reduced NRSF/REST expression due to upregulation of DYRK1A (on chromosome 21q22.13) and methylation of REST binding sites during early developmental stages may contribute to this genome-wide excess of hypermethylated sites. Upregulation of DNMT3L (on chromosome 21q22.4) could lead to de novo methylation in neuroprogenitors, which then persists in the fetal DS brain where DNMT3A and DNMT3B become downregulated. The vast majority of differentially methylated promoters and genes was hypermethylated in DS and located outside chromosome 21, including the protocadherin gamma (PCDHG) cluster on chromosome 5q31, which is crucial for neural circuit formation in the developing brain. Bisulfite pyrosequencing and targeted RNA sequencing showed that several genes of PCDHG subfamilies A and B are hypermethylated and transcriptionally downregulated in fetal DS cortex. Decreased PCDHG expression is expected to reduce dendrite arborization and growth in cortical neurons. Since constitutive hypermethylation of PCDHG and other genes affects multiple tissues, including blood, it may provide useful biomarkers for DS brain development and pharmacologic targets for therapeutic interventions. KW - trisomy 21 KW - DNA methylation KW - Down syndrome KW - fetal brain development KW - frontal cortex KW - protocadherin gamma cluster Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191239 VL - 11 IS - 8 ER - TY - JOUR A1 - Fiedler, David A1 - Hirsch, Daniela A1 - El Hajj, Nady A1 - Yang, Howard H. A1 - Hu, Yue A1 - Sticht, Carsten A1 - Nanda, Indrajit A1 - Belle, Sebastian A1 - Rueschoff, Josef A1 - Lee, Maxwell P. A1 - Ried, Thomas A1 - Haaf, Thomas A1 - Gaiser, Timo T1 - Genome‐wide DNA methylation analysis of colorectal adenomas with and without recurrence reveals an association between cytosine‐phosphate‐guanine methylation and histological subtypes JF - Genes, Chromosomes and Cancer N2 - Aberrant methylation of DNA is supposed to be a major and early driver of colonic adenoma development, which may result in colorectal cancer (CRC). Although gene methylation assays are used already for CRC screening, differential epigenetic alterations of recurring and nonrecurring colorectal adenomas have yet not been systematically investigated. Here, we collected a sample set of formalin‐fixed paraffin‐embedded colorectal low‐grade adenomas (n = 72) consisting of primary adenomas without and with recurrence (n = 59), recurrent adenomas (n = 10), and normal mucosa specimens (n = 3). We aimed to unveil differentially methylated CpG positions (DMPs) across the methylome comparing not only primary adenomas without recurrence vs primary adenomas with recurrence but also primary adenomas vs recurrent adenomas using the Illumina Human Methylation 450K BeadChip array. Unsupervised hierarchical clustering exhibited a significant association of methylation patterns with histological adenoma subtypes. No significant DMPs were identified comparing primary adenomas with and without recurrence. Despite that, a total of 5094 DMPs (false discovery rate <0.05; fold change >10%) were identified in the comparisons of recurrent adenomas vs primary adenomas with recurrence (674; 98% hypermethylated), recurrent adenomas vs primary adenomas with and without recurrence (241; 99% hypermethylated) and colorectal adenomas vs normal mucosa (4179; 46% hypermethylated). DMPs in cytosine‐phosphate‐guanine (CpG) islands were frequently hypermethylated, whereas open sea‐ and shelf‐regions exhibited hypomethylation. Gene ontology analysis revealed enrichment of genes associated with the immune system, inflammatory processes, and cancer pathways. In conclusion, our methylation data could assist in establishing a more robust and reproducible histological adenoma classification, which is a prerequisite for improving surveillance guidelines. KW - adenoma KW - DNA methylation KW - epigenetics KW - histological subtype KW - recurrence Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-212676 VL - 58 IS - 11 SP - 783 EP - 797 ER - TY - JOUR A1 - Geyer, Kathrin K. A1 - Chalmers, Iain W. A1 - MacKintosh, Neil A1 - Hirst, Julie E. A1 - Geoghegan, Rory A1 - Badets, Mathieu A1 - Brophy, Peter M. A1 - Brehm, Klaus A1 - Hoffmann, Karl F. T1 - Cytosine methylation is a conserved epigenetic feature found throughout the phylum Platyhelminthes JF - BMC Genomics N2 - Background: The phylum Platyhelminthes (flatworms) contains an important group of bilaterian organisms responsible for many debilitating and chronic infectious diseases of human and animal populations inhabiting the planet today. In addition to their biomedical and veterinary relevance, some platyhelminths are also frequently used models for understanding tissue regeneration and stem cell biology. Therefore, the molecular (genetic and epigenetic) characteristics that underlie trophic specialism, pathogenicity or developmental maturation are likely to be pivotal in our continued studies of this important metazoan group. Indeed, in contrast to earlier studies that failed to detect evidence of cytosine or adenine methylation in parasitic flatworm taxa, our laboratory has recently defined a critical role for cytosine methylation in Schistosoma mansoni oviposition, egg maturation and ovarian development. Thus, in order to identify whether this epigenetic modification features in other platyhelminth species or is a novelty of S. mansoni, we conducted a study simultaneously surveying for DNA methylation machinery components and DNA methylation marks throughout the phylum using both parasitic and non-parasitic representatives. Results: Firstly, using both S. mansoni DNA methyltransferase 2 (SmDNMT2) and methyl-CpG binding domain protein (SmMBD) as query sequences, we illustrate that essential DNA methylation machinery components are well conserved throughout the phylum. Secondly, using both molecular (methylation specific amplification polymorphism, MSAP) and immunological (enzyme-linked immunoabsorbent assay, ELISA) methodologies, we demonstrate that representative species (Echinococcus multilocularis, Protopolystoma xenopodis, Schistosoma haematobium, Schistosoma japonicum, Fasciola hepatica and Polycelis nigra) within all four platyhelminth classes (Cestoda, Monogenea, Trematoda and 'Turbellaria') contain methylated cytosines within their genome compartments. Conclusions: Collectively, these findings provide the first direct evidence for a functionally conserved and enzymatically active DNA methylation system throughout the Platyhelminthes. Defining how this epigenetic feature shapes phenotypic diversity and development within the phylum represents an exciting new area of metazoan biology. KW - methyltransferase homolog KW - echinococcus multilocularis KW - platyhelminthes KW - 5-methyl cytosine KW - gene KW - proteins KW - stem cells KW - maximum liklihood KW - schistoma mansoni KW - flatworm KW - CPG binding domain KW - DNA methylation KW - epgenetics KW - complex Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121892 SN - 1471-2164 VL - 14 IS - 462 ER - TY - THES A1 - Gohlke, Jochen T1 - Die Rolle von DNA-Methylierungen in der Entwicklung und Physiologie vonAgrobacterium-induzierten Arabidopsis-Tumoren T1 - The role of DNA methylation in development and physiology of Agrobacterium-induced Arabidopsis tumors N2 - Agrobacterium tumefaciens ist ein pathogenes Bodenbakterium, welches nach Integration seiner T-DNA in das pflanzliche Genom die Bildung von tumorartigen Wucherungen, den sogenannten Wurzelhalsgallen, an einer Reihe unterschiedlicher Wirtspflanzen verursacht. Die Expression der T-DNA-codierten Onkogene resultiert in der Proliferation und Differenzierung der sogenannten Wurzelhalsgallen, einem Prozess, welcher mit weitreichenden transkriptionellen und physiologischen Veränderungen verbunden ist. Für DNA-Methylierungen ist bekannt, dass diese zu Genexpressionsveränderungen beitragen, welche neoplastisches Wachstum in Säugetieren begünstigen. Über die Funktion epigenetischer Prozesse für die Physiologie und Entwicklung pflanzlicher Tumore ist bisher hingegen wenig bekannt. Daher wurde in dieser Arbeit das Methylierungsmuster von Wurzelhalsgallen, welche an Arabidopsis thaliana induziert wurden, sowohl genomweit als auch auf Basis einzelner Gene bestimmt. Dabei zeigte sich, dass die Onkogene ipt, iaaH und iaaM welche mit der T-DNA ins Genom integriert werden und die Proliferation auslösen, im Tumorgewebe unmethyliert vorliegen. Dennoch sind die Onkogene empfänglich gegenüber epigenetischen Modifikationen, da die siRNA-vermittelte Methylierung sowohl ihre Transkription als auch das Tumorwachstum unterbindet. Eine genomweite Studie der DNA-Methylierungsmuster mittels Tiling-Array-Analysen von immunopräzipitierter methylierter DNA zeigte ein global hypermethyliertes Tumor-Genom im Vergleich zum tumorfreien Sprossgewebe. Diese Beobachtungen stehen im Gegensatz zu den Methylierungsmustern der meisten Säuger-Tumore, welche typischerweise mit globaler Hypomethylierung und lokaler Hypermethylierung von Promotor-Sequenzen assoziiert sind. Im Unterschied dazu waren die Promoter-Sequenzen im Pflanzentumor eher hypomethyliert. Die Methylierungsunterschiede zwischen Wurzelhalsgallen und Sprossgewebe korrelierten mit transkriptionellen Veränderungen. Speziell Gene, welche in Entwicklungsprozessen und Zellteilung involviert sind, waren von Methylierungsänderungen betroffen. Dies impliziert, dass insbesondere diese Prozesse epigenetisch kontrolliert werden. Die Methylierung von Genen, welche einer transkriptionellen Kontrolle durch ABA unterliegen, war durch eine ABA-Behandlung induzierbar. DNA-Methylierungen kontrollieren somit wahrscheinlich essenzielle physiologische Prozesse während der Tumorentwicklung wie beispielsweise die ABA-vermittelte Trockenstressanpassung. Arabidopsis-Mutanten, welche in Nicht-CG-Methylierungsprozessen beeinträchtigt sind, entwickelten größere Tumore als die Kontrollpflanzen der entsprechenden Wildtypen. Dies weist auf eine Inhibierung des Tumor-Wachstums durch ein hypermethyliertes Genom, insbesondere der Nicht-CG-Motive hin. Insgesamt zeigen die Ergebnisse, dass Genexpression, physiologische Prozesse und die Entwicklung pflanzlicher Tumore einer Regulation durch DNA-Methylierung unterliegen. N2 - Agrobacterium tumefaciens is a plant pathogen which causes formation of crown gall tumors on a wide range of host species as a result of integration of its T-DNA into the plant genome. Expression of the T-DNA encoded oncogenes triggers proliferation and differentiation of crown galls, a process which is associated with severe global gene expression and physiological changes. DNA methylation changes are known to contribute to transcriptional changes which facilitate neoplastic growth in mammals. However, the role of epigenetic processes in physiology and development of plant tumors is not yet understood. Therefore, in this study the methylation pattern of Arabidopsis crown galls was analyzed on a genome-wide and single gene level. The proliferation-provoking oncogenes ipt, iaaH and iaaM, which are integrated into the plant genome along with the T-DNA, were shown to be unmethylated in the tumor genome. Nevertheless, they are susceptible to epigenetic modifications as siRNA-mediated methylation prevented both oncogene transcription and subsequent tumor development. The genome-wide analysis of DNA methylation by methylcytosine immunoprecipitation and tiling arrays revealed a globally hypermethylated tumor genome compaired to that of the tumor-free stems. This contrasts the methylation patterns in most mammalian cancers, which are typically associated with global hypomethylation and local hypermethylation of gene promoters. In crown gall tumors, promoters where rather hypomethylated. Methylation differences of crown galls and stem tissue correlated well with transcriptional changes. Especially genes involved in development and cell division were differentially methylated, implying that these processes are epigenetically controlled in the tumor. Methylation of genes which are known to be transcriptionally inhibited in an ABA-dependent manner was inducible upon ABA treatment. This suggests that DNA methylation controls essential physiological processes during crown gall development, such as ABA-mediated drought stress adaption. Arabidopsis mutants impaired in non-CG methylation developed larger tumors than wild-type controls, which indicates that hypermethylation of non-CG motifs inhibits plant tumor growth. In summary, the results of this study provide evidence that gene expression, physiological processes and the development of plant tumors are regulated by DNA methylation. KW - Abscisinsäure KW - Ackerschmalwand KW - DNS KW - Methylierung KW - Wurzelhalsgalle KW - DNA-Methylierung KW - Wurzelhalsgallen KW - ABA KW - Tumorentwicklung KW - DNA methylation KW - crown galls KW - ABA KW - tumor development Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-77732 ER - TY - JOUR A1 - Haertle, Larissa A1 - El Hajj, Nady A1 - Dittrich, Marcus A1 - Müller, Tobias A1 - Nanda, Indrajit A1 - Lehnen, Harald A1 - Haaf, Thomas T1 - Epigenetic signatures of gestational diabetes mellitus on cord blood methylation JF - Clinical Epigenetics N2 - Background: Intrauterine exposure to gestational diabetes mellitus (GDM) confers a lifelong increased risk for metabolic and other complex disorders to the offspring. GDM-induced epigenetic modifications modulating gene regulation and persisting into later life are generally assumed to mediate these elevated disease susceptibilities. To identify candidate genes for fetal programming, we compared genome-wide methylation patterns of fetal cord bloods (FCBs) from GDM and control pregnancies. Methods and results: Using Illumina’s 450K methylation arrays and following correction for multiple testing, 65 CpG sites (52 associated with genes) displayed significant methylation differences between GDM and control samples. Four candidate genes, ATP5A1, MFAP4, PRKCH, and SLC17A4, from our methylation screen and one, HIF3A, from the literature were validated by bisulfite pyrosequencing. The effects remained significant after adjustment for the confounding factors maternal BMI, gestational week, and fetal sex in a multivariate regression model. In general, GDM effects on FCB methylation were more pronounced in women with insulin-dependent GDM who had a more severe metabolic phenotype than women with dietetically treated GDM. Conclusions: Our study supports an association between maternal GDM and the epigenetic status of the exposed offspring. Consistent with a multifactorial disease model, the observed FCB methylation changes are of small effect size but affect multiple genes/loci. The identified genes are primary candidates for transmitting GDM effects to the next generation. They also may provide useful biomarkers for the diagnosis, prognosis, and treatment of adverse prenatal exposures. KW - fetal programming KW - insulin treatment KW - DNA methylation KW - fetal cord blood KW - gestational diabetes mellitus Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-159459 VL - 9 IS - 28 ER - TY - JOUR A1 - Haertle, Larissa A1 - Maierhofer, Anna A1 - Böck, Julia A1 - Lehnen, Harald A1 - Böttcher, Yvonne A1 - Blüher, Matthias A1 - Schorsch, Martin A1 - Potabattula, Ramya A1 - El Hajj, Nady A1 - Appenzeller, Silke A1 - Haaf, Thomas T1 - Hypermethylation of the non-imprinted maternal MEG3 and paternal MEST alleles is highly variable among normal individuals JF - PLoS ONE N2 - Imprinted genes show parent-specific activity (functional haploidy), which makes them particularly vulnerable to epigenetic dysregulation. Here we studied the methylation profiles of oppositely imprinted genes at single DNA molecule resolution by two independent parental allele-specific deep bisulfite sequencing (DBS) techniques. Using Roche (GSJunior) next generation sequencing technology, we analyzed the maternally imprinted MEST promoter and the paternally imprinted MEG3 intergenic (IG) differentially methylated region (DMR) in fetal cord blood, adult blood, and visceral adipose tissue. Epimutations were defined as paternal or maternal alleles with >50% aberrantly (de)methylated CpG sites, showing the wrong methylation imprint. The epimutation rates (range 2–66%) of the paternal MEST and the maternal MEG3 IG DMR allele, which should be completely unmethylated, were significantly higher than those (0–15%) of the maternal MEST and paternal MEG3 alleles, which are expected to be fully methylated. This hypermethylation of the non-imprinted allele (HNA) was independent of parental origin. Very low epimutation rates in sperm suggest that HNA occurred after fertilization. DBS with Illumina (MiSeq) technology confirmed HNA for the MEST promoter and the MEG3 IG DMR, and to a lesser extent, for the paternally imprinted secondary MEG3 promoter and the maternally imprinted PEG3 promoter. HNA leads to biallelic methylation of imprinted genes in a considerable proportion of normal body cells (somatic mosaicism) and is highly variable between individuals. We propose that during development and differentiation maintenance of differential methylation at most imprinting control regions may become to some extent redundant. The accumulation of stochastic and environmentally-induced methylation errors on the non-imprinted allele may increase epigenetic diversity between cells and individuals. KW - DNA methylation KW - genomic imprinting KW - polymerase chain reaction KW - blood KW - epigenetics KW - sequence alignment KW - sperm Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170433 VL - 12 IS - 8 ER -