Evolution of CpH methylation in vertebrate brains
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA594208 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR10606700.fastq.gz | Fastqsanger.gz | |||
| SRR10606701.fastq.gz | Fastqsanger.gz | |||
| SRR10606702.fastq.gz | Fastqsanger.gz | |||
| SRR10606703.fastq.gz | Fastqsanger.gz | |||
| SRR10606704.fastq.gz | Fastqsanger.gz |
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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.
2020-10-26 | GSE141609 | GEO
Project description:The genomes of many vertebrates show a characteristic variation in GC content. To explain its origin and evolution mainly three mechanisms have been proposed, selection for GC content, mutation bias and GC-biased gene conversion. At present the mechanism of GC-biased gene conversion, i.e. short-scale, unidirectional exchanges between homologous chromosomes in the neighborhood of recombination-initiating double-strand breaks in favor for GC nucleotides, is the most widely accepted hypothesis. We here suggest that DNA methylation also plays an important role in the evolution of GC content in vertebrate genomes. To test this hypothesis we investigated one mammalian (human; GSE30340) and one avian (chicken) genome. We used bisulfite sequencing to generate a whole-genome methylation map of chicken sperm. Human processed data files (spermdonor1, #reads>=1) were downloaded from the NGSmethDB database (http://bioinfo2.ugr.es/NGSmethDB/database.php). Inclusion of these methylation maps into a model of GC content evolution provided significant support for the impact of DNA methylation on the local equilibrium GC content. Moreover, two different estimates of equilibrium GC content, one which neglects and one which incorporates the impact of DNA methylation and the concomitant CpG hypermutability, give estimates that differ about 15% in both genomes, arguing for a strong impact of DNA methylation on the evolution of GC content. Thus, our results put forward that previous estimates of equilibrium GC content, which neglect the hypermutability of CpG dinucleotides, need to be reevaluated. Genomic DNA from chicken mature sperm was isolated, bisulfite converted and sequenced on a Illumina HiSeq instrument
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Project description:Vertebrates have highly methylated genomes at CpG positions while most invertebrates have sparsely methylated genomes. Therefore, hypermethylation is considered a major innovation that shaped the genome and the regulatory roles of DNA methylation in vertebrates. However, here we report that the marine sponge Amphimedon queenslandica, belonging to one of the earliest branching animal lineages, has evolved a hypermethylated genome with remarkable similarities to that of a vertebrate. Despite major differences in genome size and architecture, independent acquisition of hypermethylation reveal common distribution patterns and repercussions for genome regulation between both lineages. Genome wide depletion of CpGs is counterbalanced by CpG enrichment at unmethylated promoters, mirroring CpG islands. Furthermore, a subset of CpG-bearing transcription factor motifs are enriched at Amphimedon unmethylated promoters. We find that the animal-specific transcription factor NRF has conserved methyl-sensitivity over 700 million years, indicating an ancient cross-talk between transcription factors and DNA methylation. Finally, the sponge shows vertebrate-like levels of 5-hydroxymethylcytosine, the oxidative derivative of cytosine methylation involved in active demethylation. Hydroxymethylation is concentrated in regions that are enriched for transcription factor motifs and show developmentally dynamic demethylation. Together, these findings push back the links between DNA methylation and its regulatory roles to the early steps of animal evolution. Thus, the Amphimedon methylome challenges the prior hypotheses about the origins of vertebrate genome hypermethylation and its implications for regulatory complexity.
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Project description:Adaptive immunity and the five vertebrate NF-kB/Rel family members first appeared in cartilaginous fish, suggesting that NF-kB family expansion allowed the acquisition of new functions to regulate adaptive immune responses. Transcriptome profiling revealed that, even in macrophages, the NF-kB family member, c-Rel, most potently regulates a cytokine gene linked to adaptive immunity, Il12b, with limiting roles at key regulators of innate immunity. Neofunctionalization of c-Rel to regulate Il12b depends on its unique DNA-binding properties, which we examined using structural, biochemical, functional, and genomic approaches. Among our findings was functional c-Rel homodimer binding to motifs with little resemblance to canonical NF-kB motifs. To determine whether c-Rel’s unique binding properties drove c-Rel-RelA divergence, we compared binding properties in various vertebrate species. c-Rel-RelA binding properties diverged in mammals and amphibians but were comparable in earlier vertebrates, suggesting that divergent DNA binding emerged relatively late during vertebrate evolution to support increasing complexity of adaptive immune regulation.
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Project description:Stepwise Neofunctionalization of c-Rel during Vertebrate Evolution
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Project description:We compared the genome-wide patterns of DNA methylation in the brains of humans to those of our closest evolutionary relative, chimpanzees, using base-pair resolution whole-genome methylation maps of the prefrontal cortex. Our data reveal that the prefrontal cortex is the most heavily methylated among the human tissues examined so far. Nevertheless, hundreds of genes exhibit dramatically reduced levels of promoter DNA methylation in the human brain relative to the chimpanzee brain. Many of these genes are associated with neurological disorders, psychological disorders, and cancers, and are enriched for functions related to cellular metabolic processes and protein binding. Moreover, the majority of these genes exhibit higher expression in the human brain compared to the chimpanzee brain. Profiling DNA methylation map in prefrontal cortex regions of postmortem brains of three humans and three chimpanzees
2012-09-04 | E-GEOD-37202 | biostudies-arrayexpress
Project description:The genomes of many vertebrates show a characteristic variation in GC content. To explain its origin and evolution mainly three mechanisms have been proposed, selection for GC content, mutation bias and GC-biased gene conversion. At present the mechanism of GC-biased gene conversion, i.e. short-scale, unidirectional exchanges between homologous chromosomes in the neighborhood of recombination-initiating double-strand breaks in favor for GC nucleotides, is the most widely accepted hypothesis. We here suggest that DNA methylation also plays an important role in the evolution of GC content in vertebrate genomes. To test this hypothesis we investigated one mammalian (human; GSE30340) and one avian (chicken) genome. We used bisulfite sequencing to generate a whole-genome methylation map of chicken sperm. Human processed data files (spermdonor1, #reads>=1) were downloaded from the NGSmethDB database (http://bioinfo2.ugr.es/NGSmethDB/database.php). Inclusion of these methylation maps into a model of GC content evolution provided significant support for the impact of DNA methylation on the local equilibrium GC content. Moreover, two different estimates of equilibrium GC content, one which neglects and one which incorporates the impact of DNA methylation and the concomitant CpG hypermutability, give estimates that differ about 15% in both genomes, arguing for a strong impact of DNA methylation on the evolution of GC content. Thus, our results put forward that previous estimates of equilibrium GC content, which neglect the hypermutability of CpG dinucleotides, need to be reevaluated.
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Project description:Adaptive immunity and the five vertebrate NF-kB/Rel family members first appeared in cartilaginous fish, suggesting that NF-kB family expansion allowed the acquisition of new functions to regulate adaptive immune responses. Transcriptome profiling revealed that, even in macrophages, the NF-kB family member, c-Rel, most potently regulates a cytokine gene linked to adaptive immunity, Il12b, with limiting roles at key regulators of innate immunity. Neofunctionalization of c-Rel to regulate Il12b depends on its unique DNA-binding properties, which we examined using structural, biochemical, functional, and genomic approaches. Among our findings was functional c-Rel homodimer binding to motifs with little resemblance to canonical NF-kB motifs. To determine whether c-Rel’s unique binding properties drove c-Rel-RelA divergence, we compared binding properties in various vertebrate species. c-Rel-RelA binding properties diverged in mammals and amphibians but were comparable in earlier vertebrates, suggesting that divergent DNA binding emerged relatively late during vertebrate evolution to support increasing complexity of adaptive immune regulation.
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Project description:Recurrent evolution of vertebrate transcription factors via transposase capture
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Project description:DNA methylation has been found throughout animal kingdom, but it is still unclear whether this epigenetic mechanism affects the evolution of genomic elements in animals. Here, we compare the DNA methylomes of gametes and embryos from 7 representative animal species. We find that parental methylomes are propagated to the progeny without significant changes during embryogenesis in cnidarians and insects, but undergo substantial reprogramming in echinoderms, and the reprogramming become more dramatic during deuterostome evolution. Interestingly, young gene promoters in mammals tend to be reprogrammed, usually have low CpG density, don’t contain CpG Islands (CGIs) and are hypermethylated, and the hypermethylated status correlates to lower transcription. Unexpectedly, an evolutionary trend of CpG accumulation in promoters is observed only during vertebrate evolution. Most of ancient gene promoters in mammals form CGIs, which are generally unmethylated and associate with higher transcription. Thus, to gain unmethylated pattern to facilitate transcription, nature selection should be in favor of the formation of CGIs in promoters. Our data suggest that the formation of CGIs in promoters is driven by DNA methylation during mammalian evolution.
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