Project description:Genomic imprinting results in the preferential expression of the paternal, or maternal allele of certain genes. We have performed a genome-wide characterization of imprinting in the mouse embryonic and adult brain using F1 hybrid mice generated from reciprocal crosses of CASTEiJ and C57BL/6J mice. We also uncovered genes associated with sex specific parental effects in the adult mouse brain. Our study identified preferential selection of the maternally inherited X chromosome in glutamatergic neurons of the female cortex.
Project description:Parental imprinting is an epigenetic phenomenon by which genes are expressed in a monoallelic fashion, according to their parent-of-origin. DNA methylation is considered the hallmark mechanism regulating parental imprinting. To identify imprinted differentially methylated regions (DMRs), we compared the DNA methylation status between multiple normal and parthenogenetic human pluripotent stem cells (PSCs) by performing reduced representation bisulfite sequencing. Our analysis identified over twenty previously unknown imprinted DMRs in addition to the known DMRs. These include DMRs in loci associated with human disorders, and a class of intergenic DMRs that do not seem to be related to gene expression. Furthermore, the study showed some DMRs to be unstable, liable to differentiation or reprogramming. A comprehensive comparison between mouse and human DMRs identified almost half of the imprinted DMRs to be species-specific. Taken together our data map novel DMRs in the human genome, their evolutionary conservation, and relation to gene expression. RRBS profiles were generated from 6 parthenogenetic iPSC lines (hiPS A11, hiPS A20, hIPS A26, hiPS B34, hiPS B36, hiPS B41) and fibroblasts from the 2 parents whose ovarian teratomas were used to derive the iPSC lines, for a total of 8 samples.
Project description:Genomic imprinting results in the preferential expression of the paternal, or maternal allele of certain genes. We have performed a genome-wide characterization of imprinting in the mouse embryonic and adult brain using F1 hybrid mice generated from reciprocal crosses of CASTEiJ and C57BL/6J mice. We also uncovered genes associated with sex specific parental effects in the adult mouse brain. Our study identified preferential selection of the maternally inherited X chromosome in glutamatergic neurons of the female cortex. Examination of allele specific expression in the brains of reciprocal crosses of F1 hybrid mice from CASTEiJ and C57BL/6J crosses. Processed data files (GenomicAligned, SNP_calls, TranscriptomeAligned, fRNAdbAligned) and README file linked below as supplementary files.
Project description:In vitro cortex generated from embryonic stem cells (ESCs) is a model system to investigate corticogenesis and a promising tool for cortical therapy. A fundamental question that has implications for understanding corticogenesis and for using stem cells therapeutically is to determine whether in vitro cortex reproduces some fine-tuned epigenetic modifications that are important for corticogenesis and function in vivo such as parent-of-origin dependent DNA methylation and expression of imprinted genes (IGs). Here, we have compared at single-base resolution the parent-of-origin dependent DNA methylation and expression of IGs in hybrid cortices generated either in vivo or in vitro from ESCs using Reduced Representation Bisulfite Sequencing (RRBS) and RNA-seq. We report that in vitro cortex strictly reproduced the in vivo parental expression of 41 IGs, including those involved in corticogenesis such as Mest (paternal) and Cdkn1c (maternal). The expressed allele was set in ESCs and maintained during in vitro corticogenesis for most IGs but some switched from a biallelic expression in ESCs to the monoallelic expression observed in vivo. RRBS experiments revealed that parent-of-origin dependent methylation at imprinted loci were also largely similar in in vitro and in vivo cortices except at a few loci. The most discordant locus was Gpr1-Zdbf2: Zdbf2 RNA was paternal in vivo and biallelic in vitro, and this was concomitant with an aberrant gain of methylation on the maternal allele in vitro. Thus, we conclude that the epigenetic mechanisms at imprinted loci are largely but not strictly preserved in vitro. We propose that in vitro corticogenesis, with its set of IGs displaying faithful parent-of-origin dependent expression and methylation, helps to define the poorly known mechanisms regulating imprinting in the brain and roles of IGs during corticogenesis.
Project description:Several hundred mammalian genes are expressed preferentially from one parental allele due to a process called genomic imprinting. Genomic imprinting is particularly prevalent in extra-embryonic tissue, where it plays an essential role during development. Here, we profiled imprinted gene expression via RNA-Seq in a panel of six mouse trophoblast stem (TSC) lines, which are ex vivo derivatives of a progenitor population that gives rise to the placental tissue of the mouse. We found evidence of imprinted expression for 48 genes, 31 of which had previously been described as imprinted and 17 of which we suggest as candidate imprinted genes. An equal number of maternally and paternally biased genes were detected. Several genes showed variability in imprinted expression between the six TSC lines. Sixteen of the 48 known and candidate imprinted genes were previously or newly annotated noncoding RNAs, and six encoded for a total of 60 annotated microRNAs. Pyrosequencing across a panel of six TSC lines returned levels of imprinted expression that were concordant with RNA-Seq measurements for eight genes examined in all six independently derived TSC lines. Our results solidify TSCs as a cell culture-based experimental model to study genomic imprinting, and provide a quantitative foundation upon which to delineate mechanisms by which the process is maintained in the mouse. RNA-Seq from F1 hybrid TSC lines generated from crosses between Cast and B6 mice.
Project description:DNA methylation is essential for embryonic development and implicated in the regulation of genomic imprinting. Genomic imprinting is established in the germline through parent-specific methylation of distinct cis-regulatory DNA sequences, called imprinting control regions (ICRs). Which factors bind to the opposing chromatin states at ICRs within the same nuclear environment was not systematically addressed. By using a proximity labelling approach with the methylation sensitive transcription factor ZFP57, we identified ATF7IP and other major components of the epigenetic maintenance machinery at ICRs.
Project description:An undefined number of mammalian genes are expressed preferentially from one parental allele, in a process termed genomic imprinting. To shed light on the general principles of this process in a single cell type, we profiled allelic gene expression, DNaseI hypersensitivity (DHS), and CTCF binding in genetically defined murine trophoblast stem cells (TSCs). The data deposited in this entry are from CTCF ChIP-Seq and DNase-Seq experiments performed in the BC.1 cell line. All other data has been previously deposited as part of GEO Series GSE39406. The F1 TSC line profiled was generated from a cross between a C57BL/6J (B6) female and CAST/EiJ (Cast) male mouse.
Project description:Genomic imprinting is an epigenetic phenomenon leading to parental allele specific expression. Dosage of imprinted genes is crucial for normal development and its dysregulation accounts for a number of human disorders. Imprinted expression is dictated by differences in DNA methylation between parental alleles at specific regulatory elements known as imprinting control regions (ICRs). Although a number of approaches can be used for methylation inspection at ICRs, we lack an easy and cost-effective method to simultaneously measure DNA methylation at multiple imprinted regions. Here, we present IMPLICON, a new high-throughput method measuring DNA methylation levels at imprinted regions with base-pair resolution and over 1000-fold genomic coverage. We initially designed this method to look at ICRs in adult tissues of inbred mice. Then, we validated in hybrid mice from reciprocal crosses for which we could discriminate methylation profiles in the two parental alleles. Lastly, we developed a human version of IMPLICON and detected imprinting errors in naïve human embryonic and induced pluripotent stem cells. We also provide rules and guidelines in which this method can be adapted to investigate the DNA methylation landscape of any set of genomic regions. In summary, IMPLICON is a rapid, cost-effective and scalable method, which could become the gold standard in both imprinting research and diagnostics.
Project description:Genomic imprinting is an epigenetic mechanism that results in parent-of-origin monoallelic expression of specific genes, which precludes uniparental development and underlies various diseases. Here we explored molecular and developmental aspects of imprinting in humans by generating exclusively-paternal human androgenetic embryonic stem cells (aESCs) and comparing them with exclusively-maternal parthenogenetic ESCs (pESCs) and bi-parental ESCs, establishing a pluripotent-cell system of distinct parental backgrounds. Analyzing the transcriptomes and methylomes of human aESCs, pESCs and bi-parental ESCs enabled the characterization of regulatory relations at known imprinted regions and uncovered new imprinted gene candidates within and outside known imprinted regions. Investigating the consequences of uniparental differentiation, we showed the known paternal-genome preference for placental contribution, revealed a novel bias towards liver differentiation, and implicated the involvement of the imprinted gene IGF2 in this process. Our results demonstrate the utility of parent-specific human ESCs for dissecting the role of imprinting in human development and disease.
Project description:Genomic imprinting is an epigenetic mechanism that results in parent-of-origin monoallelic expression of specific genes, which precludes uniparental development and underlies various diseases. Here, we explored molecular and developmental aspects of imprinting in humans by generating exclusively paternal human androgenetic embryonic stem cells (aESCs) and comparing them with exclusively maternal parthenogenetic ESCs (pESCs) and bi-parental ESCs, establishing a pluripotent cell system of distinct parental backgrounds. Analyzing the transcriptomes and methylomes of human aESCs, pESCs, and bi-parental ESCs enabled the characterization of regulatory relations at known imprinted regions and uncovered imprinted gene candidates within and outside known imprinted regions. Investigating the consequences of uniparental differentiation, we showed the known paternal-genome preference for placental contribution, revealed a similar bias toward liver differentiation, and implicated the involvement of the imprinted gene IGF2 in this process. Our results demonstrate the utility of parent-specific human ESCs for dissecting the role of imprinting in human development and disease.