DNA Methyltransferases, DNA Methylation, and Age-Associated Cognitive Function.
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ABSTRACT:
SUBMITTER: Cui D
PROVIDER: S-EPMC5983821 | biostudies-other | 2018 Apr
REPOSITORIES: biostudies-other
Publications
DNA Methyltransferases, DNA Methylation, and Age-Associated Cognitive Function.
International journal of molecular sciences 20180428 5
Ageing, a leading cause of the decline/deficits in human learning, memory, and cognitive abilities, is a major risk factor for age-associated neurodegenerative disorders such as Alzheimer’s disease. Emerging evidence suggests that epigenetics, an inheritable but reversible biochemical process, plays a crucial role in the pathogenesis of age-related neurological disorders. DNA methylation, the best-known epigenetic mark, has attracted most attention in this regard. DNA methyltransferases (D ...[more]
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Project description:The prevailing views as to the form, function, and regulation of genomic methylation patterns have their origin many years in the past, at a time when the structure of the mammalian genome was only dimly perceived, when the number of protein-encoding mammalian genes was believed to be at least five times greater than the actual number, and when it was not understood that only ~10% of the genome is under selective pressure and likely to have biological function. We use more recent findings from genome biology and whole-genome methylation profiling to provide a reappraisal of the shape of genomic methylation patterns and the nature of the changes that they undergo during gametogenesis and early development. We observe that the sequences that undergo deep changes in methylation status during early development are largely sequences without regulatory function. We also discuss recent findings that begin to explain the remarkable fidelity of maintenance methylation. Rather than a general overview of DNA methylation in mammals (which has been the subject of many reviews), we present a new analysis of the distribution of methylated CpG dinucleotides across the multiple sequence compartments that make up the mammalian genome, and we offer an updated interpretation of the nature of the changes in methylation patterns that occur in germ cells and early embryos. We discuss the cues that might designate specific sequences for demethylation or de novo methylation during development, and we summarize recent findings on mechanisms that maintain methylation patterns in mammalian genomes. We also describe the several human disorders, each very different from the other, that are caused by mutations in DNA methyltransferase genes.
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Project description:DNA methylation (DNAm) plays diverse roles in human biology, but this dynamic epigenetic mark remains far from fully characterized. Although earlier studies uncovered loci that undergo age-associated DNAm changes in adults, little is known about such changes during childhood. Despite profound DNAm plasticity during embryogenesis and early development, monozygotic twins show indistinguishable childhood methylation, suggesting DNAm is highly coordinated during the pediatric period. Here we examine the methylation of 27,578 CpG dinucleotides in peripheral blood DNA from 398 boys, aged 3 to 17 years, and find significant age-associated changes in DNAm at 2,078 loci. We report a deficit of such loci on the X chromosome, a preference for specific nucleotides immediately surrounding the interrogated CpG dinucleotide, and a primary association with developmental and immune ontological functions. These pediatric age-associated loci overlap significantly with those previously identified in adults (p < 0.001) but most of the pediatric loci are unique, suggesting many are childhood-specific. Meta-analysis (n = 1080) with two adult studies reveals that the methylation changes in 29.5% of the age-associated pediatric loci follow a linear pattern from childhood into adulthood; however, we also find a three-fold higher rate of change in children compared with adults and that a higher proportion of lifelong changes are more accurately modeled as a function of logarithmic age. We therefore conclude that DNAm changes occur more rapidly during childhood and are imperfectly accounted for by statistical corrections that are linear in age, further suggesting that future DNAm studies are matched closely for age. Age associated DNA methylation was evaluated at each CpG locus using a fixed-effects linear regression model adjusting for BeadChip as a covariate to account for batch effects. Analysis of variance (ANOVA) was conducted for each CpG locus to assess the age affect at each CpG locus which was subsequently corrected for multiple hypotheses using a Benjamini-Hochberg FDR. SUPPLEMENTARY FILES: * Matrix_AllSampleDetection.txt: Detection P-values for each sample and each loci * Matrix_AllSampleSignal.txt: Signal for Probe A and Probe B for each sample and each loci * Matrix_Non-Normalized_AllSampleBeta.txt: Beta values calculated using GenomeStudio v2010.3 Methylation Module 1.8.5 as Signal of Probe B / (Signal of Probe A + Signal of Probe B + 100) * Matrix_Normalized_AllSampleBetaPrime.txt: Beta Prime values used for analysis calculated from the Probe B and Probe A signals as Beta Prime = Signal of Probe B / (Signal of Probe A + Signal of Probe A)
2012-02-01 | E-GEOD-27097 | biostudies-arrayexpress
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Project description:DNA methylation (DNAm) plays diverse roles in human biology, but this dynamic epigenetic mark remains far from fully characterized. Although earlier studies uncovered loci that undergo age-associated DNAm changes in adults, little is known about such changes during childhood. Despite profound DNAm plasticity during embryogenesis and early development, monozygotic twins show indistinguishable childhood methylation, suggesting DNAm is highly coordinated during the pediatric period. Here we examine the methylation of 27,578 CpG dinucleotides in peripheral blood DNA from 398 boys, aged 3 to 17 years, and find significant age-associated changes in DNAm at 2,078 loci. We report a deficit of such loci on the X chromosome, a preference for specific nucleotides immediately surrounding the interrogated CpG dinucleotide, and a primary association with developmental and immune ontological functions. These pediatric age-associated loci overlap significantly with those previously identified in adults (p < 0.001) but most of the pediatric loci are unique, suggesting many are childhood-specific. Meta-analysis (n = 1080) with two adult studies reveals that the methylation changes in 29.5% of the age-associated pediatric loci follow a linear pattern from childhood into adulthood; however, we also find a three-fold higher rate of change in children compared with adults and that a higher proportion of lifelong changes are more accurately modeled as a function of logarithmic age. We therefore conclude that DNAm changes occur more rapidly during childhood and are imperfectly accounted for by statistical corrections that are linear in age, further suggesting that future DNAm studies are matched closely for age.
2012-02-01 | GSE27097 | GEO