Project description:We did RNA-seq analysis to compare gene expression profiles in mouse embryos with or without ZFP57. We also perfromed whole-genome bisulfite sequencing analysis (WGBS) for the Zfp57 mutant mouse embryos and control heterozygous embryos. We analyzed DNA methylation at the imprinting control regions (ICRs), differentially methylation regions (DMRs) and repetitive elements including LINE-1, LINE-2, SINE, LTR and IAP.
Project description:Selective maintenance of genomic methylation imprints during pre-implantation development is required for parental origin-specific expression of imprinted genes. The Kruppel-like zinc finger protein ZFP57 acts as a factor necessary for maintaining the DNA methylation memory at multiple imprinting control regions (ICRs) in early mouse embryos and ES cells. Maternal-zygotic deletion of ZFP57 in mice presents a highly penetrant phenotype with no animals surviving to birth. In addition, several cases of human transient neonatal diabetes (TND) are associated with somatic mutations in ZFP57 coding sequence. Here we comprehensively map sequence-specific ZFP57 binding sites in an allele-specific manner using hybrid ES cell lines from reciprocal crosses between C57BL/6J and Cast/EiJ mice assigning allele specificity to approximately two thirds of all binding sites. While half of these are biallelic and include ERV targets, the rest show mono-allelic binding based either on parental-origin or on genetic background of the allele. Parental-origin allele-specific binding was methylation-dependent and mapped only to imprinted DMRs established in the germline (gDMRs). No binding was evident at secondary somatically-derived DMRs. ZFP57-bound gDMRs can predict imprinted gene expression and we identify new imprinted genes, including the Fkbp6 gene with a critical function in mouse male germ cell development. Genetic-background specific sequence differences also influence ZFP57 binding. We show that genetic variation that disrupts the consensus binding motif and its methylation is associated with mono-allelic expression of neighbouring genes. The work described here uncovers further roles for ZFP57 mediated regulation of genomic imprinting and identifies a novel mechanism for genetically determined mono-allelic gene expression. Input and Zfp57 CHiP-Seq profiles of hybrid Black6/Cast ES cells were generated by sequencing using the Illumina GAIIx platform.
Project description:Selective maintenance of genomic methylation imprints during pre-implantation development is required for parental origin-specific expression of imprinted genes. The Kruppel-like zinc finger protein ZFP57 acts as a factor necessary for maintaining the DNA methylation memory at multiple imprinting control regions (ICRs) in early mouse embryos and ES cells. Maternal-zygotic deletion of ZFP57 in mice presents a highly penetrant phenotype with no animals surviving to birth. In addition, several cases of human transient neonatal diabetes (TND) are associated with somatic mutations in ZFP57 coding sequence. Here we comprehensively map sequence-specific ZFP57 binding sites in an allele-specific manner using hybrid ES cell lines from reciprocal crosses between C57BL/6J and Cast/EiJ mice assigning allele specificity to approximately two thirds of all binding sites. While half of these are biallelic and include ERV targets, the rest show mono-allelic binding based either on parental-origin or on genetic background of the allele. Parental-origin allele-specific binding was methylation-dependent and mapped only to imprinted DMRs established in the germline (gDMRs). No binding was evident at secondary somatically-derived DMRs. ZFP57-bound gDMRs can predict imprinted gene expression and we identify new imprinted genes, including the Fkbp6 gene with a critical function in mouse male germ cell development. Genetic-background specific sequence differences also influence ZFP57 binding. We show that genetic variation that disrupts the consensus binding motif and its methylation is associated with mono-allelic expression of neighbouring genes. The work described here uncovers further roles for ZFP57 mediated regulation of genomic imprinting and identifies a novel mechanism for genetically determined mono-allelic gene expression.
Project description:ZFP57 interacts with the germline-derived differentially methylated regions (DMRs) of imprinted genes, and is required to maintain DMR methylation in mouse embryonic stem cells (ESCs). Although DNA methylation has a key role in maintaining genomic imprinting, several imprinted genes are controlled by different mechanisms, and a comprehensive study of the relationship between DMR methylation and imprinted gene expression is lacking. To address this issue, we differentiated wild-type and Zfp57 -/- hybrid mouse ESCs into neural precursor cells (NPCs) and evaluated allelic expression of imprinted genes. In Zfp57-mutant NPCs, we observed loss of allelic bias of all the 35 genes that were imprinted in wild-type cells, demonstrating that Zfp57-dependent methylation is required to globally maintain gene expression imprinting. Analysis of bulk expression showed that most of the genes expressed from the non-methylated chromosome were up-regulated, and most of those expressed from the methylated chromosome were down-regulated in mutant cells, but also that several other imprinted genes acquiring biallelic expression were not significantly affected, suggesting the existence of compensatory mechanisms that control their RNA level. Since neuronal differentiation was impaired in Zfp57-mutant cells, this study also indicates that deregulation of imprinted genes and/or other ZFP57-target non-imprinted genes is incompatible with proper neurogenesis.
Project description:ZFP57 is necessary for maintaining repressive epigenetic modifications at Imprinting control regions (ICRs). In mouse embryonic stem cells (ESCs), ZFP57 binds ICRs (ICRBS) and many other loci (non-ICRBS). To address the role of ZFP57 on all its target sites, we performed high-throughput and multi-locus analyses of inbred and hybrid mouse ESC lines carrying different gene knockouts. By using an allele-specific RNA-seq approach, we demonstrate that ZFP57 loss results in derepression of the imprinted allele of multiple genes in the imprinted clusters. We also find marked epigenetic differences between ICRBS and non-ICRBS suggesting that different cis-acting regulatory functions are repressed by ZFP57 at these two classes of target loci. Overall, these data demonstrate that ZFP57 is pivotal to maintain the allele-specific epigenetic modifications of ICRs that in turn are necessary for maintaining the imprinted expression over long distances. At non-ICRBS, ZFP57 inactivation results in acquisition of epigenetic features that are characteristic of poised enhancers, suggesting that another function of ZFP57 in early embryogenesis is to repress cis-acting regulatory elements whose activity is not yet required.
Project description:ZFP57 is necessary for maintaining repressive epigenetic modifications at Imprinting control regions (ICRs). In mouse embryonic stem cells (ESCs), ZFP57 binds ICRs (ICRBS) and many other loci (non-ICRBS). To address the role of ZFP57 on all its target sites, we performed high-throughput and multi-locus analyses of inbred and hybrid mouse ESC lines carrying different gene knockouts. By using an allele-specific RNA-seq approach, we demonstrate that ZFP57 loss results in derepression of the imprinted allele of multiple genes in the imprinted clusters. We also find marked epigenetic differences between ICRBS and non-ICRBS suggesting that different cis-acting regulatory functions are repressed by ZFP57 at these two classes of target loci. Overall, these data demonstrate that ZFP57 is pivotal to maintain the allele-specific epigenetic modifications of ICRs that in turn are necessary for maintaining the imprinted expression over long distances. At non-ICRBS, ZFP57 inactivation results in acquisition of epigenetic features that are characteristic of poised enhancers, suggesting that another function of ZFP57 in early embryogenesis is to repress cis-acting regulatory elements whose activity is not yet required.
Project description:ZFP57 is necessary for maintaining repressive epigenetic modifications at Imprinting control regions (ICRs). In mouse embryonic stem cells (ESCs), ZFP57 binds ICRs (ICRBS) and many other loci (non-ICRBS). To address the role of ZFP57 on all its target sites, we performed high-throughput and multi-locus analyses of inbred and hybrid mouse ESC lines carrying different gene knockouts. By using an allele-specific RNA-seq approach, we demonstrate that ZFP57 loss results in derepression of the imprinted allele of multiple genes in the imprinted clusters. We also find marked epigenetic differences between ICRBS and non-ICRBS suggesting that different cis-acting regulatory functions are repressed by ZFP57 at these two classes of target loci. Overall, these data demonstrate that ZFP57 is pivotal to maintain the allele-specific epigenetic modifications of ICRs that in turn are necessary for maintaining the imprinted expression over long distances. At non-ICRBS, ZFP57 inactivation results in acquisition of epigenetic features that are characteristic of poised enhancers, suggesting that another function of ZFP57 in early embryogenesis is to repress cis-acting regulatory elements whose activity is not yet required.
Project description:ZFP57 is necessary for maintaining repressive epigenetic modifications at Imprinting control regions (ICRs). In mouse embryonic stem cells (ESCs), ZFP57 binds ICRs (ICRBS) and many other loci (non-ICRBS). To address the role of ZFP57 on all its target sites, we performed high-throughput and multi-locus analyses of inbred and hybrid mouse ESC lines carrying different gene knockouts. By using an allele-specific RNA-seq approach, we demonstrate that ZFP57 loss results in derepression of the imprinted allele of multiple genes in the imprinted clusters. We also find marked epigenetic differences between ICRBS and non-ICRBS suggesting that different cis-acting regulatory functions are repressed by ZFP57 at these two classes of target loci. Overall, these data demonstrate that ZFP57 is pivotal to maintain the allele-specific epigenetic modifications of ICRs that in turn are necessary for maintaining the imprinted expression over long distances. At non-ICRBS, ZFP57 inactivation results in acquisition of epigenetic features that are characteristic of poised enhancers, suggesting that another function of ZFP57 in early embryogenesis is to repress cis-acting regulatory elements whose activity is not yet required.
Project description:Differences in chromatin state inherited from the parental gametes influence the regulation of maternal and paternal alleles in offspring. This phenomenon, known as genomic imprinting, results in genes preferentially transcribed from one parental allele. While local epigenetic factors such as DNA methylation are known to be important for the establishment of imprinted gene expression, less is known about the mechanisms by which differentially methylated regions (DMRs) lead to differences in allelic expression across broad stretches of chromatin. Allele-specific higher-order chromatin structure has been observed at multiple imprinted loci, consistent with the observation of allelic binding of the chromatin-organizing factor CTCF at multiple DMRs. However, whether allelic chromatin structure impacts allelic gene expression is not known for most imprinted loci. Here we characterize the mechanisms underlying brain-specific imprinted expression of the Peg13-Kcnk9 locus, an imprinted region associated with intellectual disability. We performed region capture Hi-C on mouse brain from reciprocal hybrid crosses and found imprinted higher-order chromatin structure caused by the allelic binding of CTCF to the Peg13 DMR. Using an in vitro neuron differentiation system, we show that on the maternal allele, an enhancer-promoter contact formed early in development primes the brain-specific potassium leak channel Kcnk9 for maternal expression prior to neurogenesis. In contrast, this enhancer-promoter contact is blocked by CTCF on the paternal allele, preventing paternal Kcnk9 activation. This work provides a high-resolution map of imprinted chromatin structure and demonstrates that chromatin state established in early development can promote imprinted expression upon differentiation.