Project description:Genomic imprinting is a form of epigenetic regulation that results in expression of either the maternally or paternally inherited allele of a subset of genes. Imprinted loci contain differentially methylated regions (DMRs) where cytosine methylation marks one of the parental alleles, providing cis-acting regulatory elements that influence the allelic expression of surrounding genes, however to date the total number of imprinted loci within the human genome is unknown. To characterize known imprinted DMRS and identify novel imprinted loci we have performed whole-genome bisulphite sequencing and high-resolution DNA methylation array analysis of healthy tissues.
Project description:Genomic imprinting is a form of epigenetic regulation that results in expression of either the maternally or paternally inherited allele of a subset of genes. Imprinted loci contain differentially methylated regions (DMRs) where cytosine methylation marks one of the parental alleles, providing cis-acting regulatory elements that influence the allelic expression of surrounding genes, however to date the total number of imprinted loci within the human genome is unknown. To characterize known imprinted DMRS and identify novel imprinted loci we have performed whole-genome bisulphite sequencing and high-resolution DNA methylation array analysis of healthy tissues.
Project description:Genomic imprinting is an epigenetic mechanism leading to parent-of-origin silencing of alleles. So far, the precise number of imprinted regions in humans is uncertain. In this study, we leveraged genome-wide DNA methylation in whole blood measured longitudinally at three time points (birth, childhood and adolescence) and genome-wide association studies (GWAS) data in 740 mother-child duos from the Avon Longitudinal Study of parents and children to identify candidate imprinted loci. We reasoned that cis-meQTLs at genomic regions that were imprinted would show strong evidence of parent-of-origin associations with DNA methylation, enabling the detection of imprinted regions. Using this approach, we identified genome-wide significant cis-meQTLs that exhibited parent-of-origin effects (POEs) at 82 loci, 34 novel and 48 regions previously implicated in imprinting (3.7-10<P?<?10-300). Using an independent dataset from the Brisbane Systems Genetic Study, we replicated 76 out of the 82 identified loci. POEs were remarkably consistent across time points and were so strong at some loci that methylation levels enabled good discrimination of parental transmissions at these and surrounding genomic regions. The implication is that parental allelic transmissions could be modelled at many imprinted (and linked) loci in GWAS of unrelated individuals given a combination of genetic and methylation data. Novel regions showing parent of origin effects on methylation will require replication using a different technology and further functional experiments to confirm that such effects arise through a genomic imprinting mechanism.
Project description:Genomic imprinting is a form of epigenetic regulation that results in expression of either the maternally or paternally inherited allele of a subset of genes. Imprinted loci contain differentially methylated regions (DMRs) where cytosine methylation marks one of the parental alleles, providing cis-acting regulatory elements that influence the allelic expression of surrounding genes, however to date the total number of imprinted loci within the human genome is unknown. To characterize known imprinted DMRS and identify novel imprinted loci we have performed whole-genome bisulphite sequencing and high-resolution DNA methylation array analysis of healthy tissues. Sequencing of bisulfite converted DNA analysis of normal brain (white matter), liver and term placenta tissue
Project description:Genomic imprinting is a form of epigenetic regulation that results in expression of either the maternally or paternally inherited allele of a subset of genes. Imprinted loci contain differentially methylated regions (DMRs) where cytosine methylation marks one of the parental alleles, providing cis-acting regulatory elements that influence the allelic expression of surrounding genes, however to date the total number of imprinted loci within the human genome is unknown. To characterize known imprinted DMRS and identify novel imprinted loci we have performed whole-genome bisulphite sequencing and high-resolution DNA methylation array analysis of healthy tissues. Sequencing of bisulfite converted DNA and array based analysis of normal tissues, human embryonic stem cells, androgenetic hydatidiform moles and leukocytes from reciprocal genome-wide uniparental disomies.
Project description:Differential methylation between the two alleles of a gene has been observed in imprinted regions, where the methylation of one allele occurs on a parent-of-origin basis, the inactive X-chromosome in females, and at those loci whose methylation is driven by genetic variants. We have extensively characterized imprinted methylation in a substantial range of normal human tissues, reciprocal genome-wide uniparental disomies, and hydatidiform moles, using a combination of whole-genome bisulfite sequencing and high-density methylation microarrays. This approach allowed us to define methylation profiles at known imprinted domains at base-pair resolution, as well as to identify 21 novel loci harboring parent-of-origin methylation, 15 of which are restricted to the placenta. We observe that the extent of imprinted differentially methylated regions (DMRs) is extremely similar between tissues, with the exception of the placenta. This extra-embryonic tissue often adopts a different methylation profile compared to somatic tissues. Further, we profiled all imprinted DMRs in sperm and embryonic stem cells derived from parthenogenetically activated oocytes, individual blastomeres, and blastocysts, in order to identify primary DMRs and reveal the extent of reprogramming during preimplantation development. Intriguingly, we find that in contrast to ubiquitous imprints, the majority of placenta-specific imprinted DMRs are unmethylated in sperm and all human embryonic stem cells. Therefore, placental-specific imprinting provides evidence for an inheritable epigenetic state that is independent of DNA methylation and the existence of a novel imprinting mechanism at these loci.