Project description:In honey bees (Apis mellifera) the behaviorally and reproductively distinct queen and worker female castes derive from the same genome as a result of differential intake of royal jelly and are implemented in concert with DNA methylation. To determine if these very different diet-controlled phenotypes correlate with unique brain methylomes, we conducted a study to determine the methyl cytosine (mC) distribution in the brains of queens and workers at single-base-pair resolution using shotgun bisulfite sequencing technology. The whole-genome sequencing was validated by deep 454 sequencing of selected amplicons representing eight methylated genes. We found that nearly all mCs are located in CpG dinucleotides in the exons of 5,854 genes showing greater sequence conservation than non-methylated genes. Over 550 genes show significant methylation differences between queens and workers, revealing the intricate dynamics of methylation patterns. The distinctiveness of the differentially methylated genes is underscored by their intermediate CpG densities relative to drastically CpG-depleted methylated genes and to CpG-richer non-methylated genes. We find a strong correlation between methylation patterns and splicing sites including those that have the potential to generate alternative exons. We validate our genome-wide analyses by a detailed examination of two transcript variants encoded by one of the differentially methylated genes. The link between methylation and splicing is further supported by the differential methylation of genes belonging to the histone gene family. We propose that modulation of alternative splicing is one mechanism by which DNA methylation could be linked to gene regulation in the honey bee. Our study describes a level of molecular diversity previously unknown in honey bees that might be important for generating phenotypic flexibility not only during development but also in the adult post-mitotic brain. This study looked at the DNA methylation levels of queen and worker honeybees
Project description:We report the application of single molecule-based sequencing technology for high-throughput genom-wide mapping of MeCP2 binding and DNA methylation in mouse brain and cerebellum respectively. We find a good correlation between MeCP2 occupancy and methyl-CpG density and depletion of MeCP2 binding at CpG Islands, the majority of which are constitutively hypomethylated. This study provides a comprehensive characterisation of the genome wide distribution of MeCP2. Examination of MeCP2 occupancy in mouse brain and the distribution of methylation in mouse cerebellum.
Project description:In honey bees (Apis mellifera) the behaviorally and reproductively distinct queen and worker female castes derive from the same genome as a result of differential intake of royal jelly and are implemented in concert with DNA methylation. To determine if these very different diet-controlled phenotypes correlate with unique brain methylomes, we conducted a study to determine the methyl cytosine (mC) distribution in the brains of queens and workers at single-base-pair resolution using shotgun bisulfite sequencing technology. The whole-genome sequencing was validated by deep 454 sequencing of selected amplicons representing eight methylated genes. We found that nearly all mCs are located in CpG dinucleotides in the exons of 5,854 genes showing greater sequence conservation than non-methylated genes. Over 550 genes show significant methylation differences between queens and workers, revealing the intricate dynamics of methylation patterns. The distinctiveness of the differentially methylated genes is underscored by their intermediate CpG densities relative to drastically CpG-depleted methylated genes and to CpG-richer non-methylated genes. We find a strong correlation between methylation patterns and splicing sites including those that have the potential to generate alternative exons. We validate our genome-wide analyses by a detailed examination of two transcript variants encoded by one of the differentially methylated genes. The link between methylation and splicing is further supported by the differential methylation of genes belonging to the histone gene family. We propose that modulation of alternative splicing is one mechanism by which DNA methylation could be linked to gene regulation in the honey bee. Our study describes a level of molecular diversity previously unknown in honey bees that might be important for generating phenotypic flexibility not only during development but also in the adult post-mitotic brain.
Project description:To further our understanding of the role of DNA methylation in development, Methylated DNA Immunoprecipitation (MeDIP) was used in conjunction with a NimbleGen promoter plus CpG island array to identify Tissue and Developmental Stage specific Differentially Methylated DNA Regions (T-DMRs and DS-DMRs) on a genome-wide basis. Four tissues (brain, heart, liver, and testis) from C57BL/6J mice were analyzed at three developmental stages (15 day embryo, E15; new born, NB; 12 week adult, AD). Almost 5,000 adult T-DMRs and 10,000 DS-DMRs were identified. Surprisingly, almost all DS-DMRs were tissue specific (i.e., methylated and ummenthylated in one or more non-overlapping tissues), indicating that the vast majority of unique sequence DNA methylation has tissue specificity. Also, many DS-DMRs were methylated at early development stages (E15 and NB) but unmethylated in adult, indicating “demethylation” has a prominent role in tissue differentiation. The pattern of DNA methylation in adult testis was dramatically different from somatic tissues in many aspects, mostly notably with a very strong bias of methylation in non-CpGi (CpG island) promoter regions (94%). Although the majority of T-DMRs and DS-DMRs tended to be in non-CpGi promoter regions, a relatively large number were also located in CpGi in promoter, intra-genic and inter-genic regions (>15% of all CpGi). Gene Ontology analysis of genes with methylation in non-CpGi promoters indicates enrichment of genes related to membrane proteins and G-protein coupled receptors. Our data also suggest regulatory roles of DNA methylation outside of promoter regions and in alternative promoter selection. Overall, our studies indicate that change in DNA methylation during development is a dynamic, widespread and tissue-specific process involving both DNA methylation and demethylation. Comparison of DNA methylation across 3 developmental stages (15 day embryo, newborn, and adult) for four tissues (brain, heart, liver and testis)
Project description:The brain requires complex mechanisms of genome regulation to encode and store behavioural information. In mammals, DNA methylation deposited at non-CG dinucleotides characterises brain epigenomes. However, it is unclear to what extent this non-canonical form of DNA methylation is evolutionarily conserved. To test this we profile brain cytosine methylation across the major vertebrate lineages, amphioxus, honeybee and octopus, finding that non-CG methylation in adult brain methylomes is restricted to vertebrates. In vertebrates, the genomic patterns of non-CG do not recapitulate those of CG methylation, yet both patterns are deeply conserved. Whereas low levels of gene body CG methylation demarcate a set of developmental transcription factors across tissues and species, a distinct set of neurodevelopmental genes accumulate non-CG methylation in neural tissues. We further show that the establishment of this methylation context coincides with the origin of the “writer” of non-CG methylation, the methyltransferase DNMT3A, and the “reader”, the methyl-CpG binding protein 2 (MeCP2), fuelled by the ancestral whole genome duplication in vertebrates. Surprisingly, MeCP2 evolved in a stepwise process, from an ancestral MBD4 protein with a dual role in transcriptional regulation and DNA repair in chordates. In sum, we show how a novel neural epigenomic layer assembled at the root of vertebrates and gained new regulatory roles partly independent from CG methylation, which could have fostered the sophisticated cognitive repertoires found in the vertebrate lineage.
Project description:Glioblastoma (GBM) is an incurable brain tumor carrying a dismal prognosis, which displays considerable heterogeneity. We have recently identified recurrent H3F3A mutations affecting two critical positions of histone H3.3 (K27, G34) in one-third of pediatric GBM. Here we show that each of these H3F3A mutations defines an epigenetic subgroup of GBM with a distinct global methylation pattern, and are mutually exclusive with IDH1 mutations (characterizing a CpG-Island Methylator Phenotype (CIMP) subgroup). Three further epigenetic subgroups were enriched for hallmark genetic events of adult GBM (EGFR amplification, CDKN2A/B deletion) and/or known transcriptomic signatures. We also demonstrate that the two H3F3A mutations give rise to GBMs in separate anatomic compartments, with differential regulation of OLIG1/2 and FOXG1, possibly reflecting different cellular origins. We identified six epigenetic and biological GBM subgroups displaying distinct global DNA methylation patterns, which harbor unique hotspot mutations, DNA copy-number alterations, and transcriptomic patterns. We investigated a subset of childhood (n=59) and adult GBMs (n=77) using the Illumina 450k methylation array. Six non-neoplastic brain tissue samples are included as controls.
Project description:DNA methylation is a dynamic process through which specific chromatin modifications can be stably transmitted from parent to daughter cells. A large body of work has suggested that DNA methylation influences gene expression by silencing gene promoters. However, these conclusions were drawn from data focused mostly on promoter regions. With regards to the entire genome, it is unclear how methylation and gene transcription patterns are related during vertebrate development. To identify the genome-wide distribution of CpG methylation we created series of high-resolution methylome maps of Danio rerio embryos during development and in mature, differentiated tissues. We find that embryonic and terminal tissues have unique methylation signatures in CpG islands and repetitive sequences. Fully differentiated tissues have increased CpG and LTR methylation and decreased SINE methylation relative to embryonic tissues. Unsupervised clustering analyses reveal that the embryonic and terminal tissues can be classified solely by their methylation patterning. Novel analyses also identify a previously undescribed genome-wide exon methylation signature. We also compared whole genome methylation with genome-wide mRNA expression levels using publicly available RNA-seq datasets. These comparisons revealed previously unrecognized relationships between gene-expression, alternative splicing and exon methylation. Surprisingly, we find that exonic methylation is a better predictor of mRNA expression level than promoter methylation. We also found that transcriptionally skipped exons have significantly less methylation than retained exons. Our integrative analyses reveal highly complex interplay between gene expression, alternative splicing, development, and methylation patterning in zebrafish. MBD-Seq with whole embryos (sperm, 1cell, mbt, 3dpf) and adult tissues (eye, brain, heart, liver) Please note that the mePoor brain lane4 sample raw data files were used as loading/sequencing controls for the following meRich.lane4 samples; eye_meRich.lane4 heart_meRich.lane4 liver_meRich.lane4 The mePoor brain lane5 sample raw data files were used as loading/sequencing controls for the following meRich.lane5 samples; 1cell_meRich.lane5 mbt_meRich.lane5 sperm_meRich.lane5
Project description:DNA methylation changes in neuroblastoma, a clinically-heterogeneous pediatric tumor, have been described essentially in promoter regions. We analyzed the DNA methylome of neuroblastoma using high-density microarrays and observed differential methylation not only in promoters but also in intragenic and intergenic regions at both CpG and non-CpG sites. These epigenetic changes showed a non-random distribution relative functional chromatin domains, and targeted development and cancer-related genes, relevant for neuroblastoma pathogenesis. CCND1, a gene overexpressed in neuroblastoma, showed hypomethylation of gene-body and upstream regulatory regions. Furthermore, tumors with diverse clinical-risk showed clear differences affecting CpG and, remarkably, non-CpG sites. Non-CpG methylation was present in clinically-favorable tumors and affected genes such as ALK, where non-CpG methylation correlated with low gene expression. Finally, we identified CpG and non-CpG methylation signatures which correlated with patient’s age at time-points relevant for neuroblastoma clinical behavior, and targeted genes related to neural development and neural crest regulatory network We report on the first DNA methylomes of neuroblastoma tumors using high-density microarrays. DNA methylation changes in this pediatric tumor affected both CpG and non-CpG sites associated with developmental and cancer-related genes such as CCND1 and ALK. Our study also provides new insights into the molecular basis of the heterogeneous clinical behavior of neuroblastoma.