Project description:We previously reported a child with transient neonatal diabetes mellitus (TNDM), who upon molecular diagnosis was homozygous for a one base-pair deletion in ZFP57, inheriting the mutations from both heterozygous parents. Methylation profiling at diagnosis revealed severe hypomethylation at PLAGL1 and mosaic loss-of-methylation (LOM) at GRB10, NAP1L5 and GNAS-XL DMRs. Some years after the first child, a second sibling was born with a comparable clinical presentation. Upon molecular investigation this child was shown to have the same homozygous deletion. Using Illumina Infinium BeadChip arrays, we confirmed similar hypomethylated signatures at ubiquitous imprinted DMRs. To further characterize the stability of the imprinting defects and understand the role of this mutation in tissue-specific mosaicism, we hybridised buccal-derived DNA and a second leukocyte sample from first child to the HumanMethylationEPIC arrays. When comparing the two blood-derived samples, we observed that the hypomethylation signature is stable over time with the PLAGL1 DMR being the most severely affected, consistent with this being the disease-causing locus. Furthermore, when comparing the leukocyte and buccal samples, the same imprinted DMRs were affected to a similar extent.
Project description:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated alleles resist de novo methylation remains unclear. Using an allelic Dlk1-Dio3 ICR methylation reporter and genome-wide loss-of-function screening, we identify the zinc finger protein GZF1 that binds the unmethylated maternal ICR and protects it from de novo methylation via a regulatory element containing GZF1 and ZFP57 motifs that mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss results in maternalization. Remarkably, GZF1 protects the unmethylated ICR from de novo methylation in both oocytes and embryos, and its loss leads to perinatal death consistent with paternalization of the maternal allele. Together, our findings establish a reciprocal mechanism that maintains parental epigenetic asymmetry across both imprint establishment and embryonic reprogramming.
Project description:The aim of our study was to characterize the genotypic and phenotypic extent of multi-locus imprinting disturbances. Therefore, we analyzed the DNA methylation pattern of 37 individuals with different DNA methylation disturbances. Of these 37 individuals 17 were previously diagnosed with a multi-locus methylation disturbance (MLID) and the remaing 20 were diagnosed with a typical single locus imprinting disorder (SLID). We compared the DNA methylation of these 37 individuals to the DNA methylation of 38 evaluable individuals born small for gestational age. Our analysis revealed 21/37 individuals with a multi-locus methylation disturbances, characterzied by an aberrant DNA methylation in more than one imprintend gene region. Validation analyses were performed by bisulfite-pyrosequencing in the two imprinted gene regions ZDBF2 and FAM50B. Our analyses revealed each one patient previously diagnosed with Temple- and Angelman syndrome to have MLID. Furthermore, we showed that many of the aberrantly methylated imprinted gene regions in patients with MLID are not associated with the so far known typical imprinting disorders.
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:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated imprinted alleles resist de novo methylation remains unclear. Using an allelic methylation reporter at the Dlk1-Dio3 ICR and a genome-wide loss-of-function screen, we identify that the zinc finger protein GZF1 specifically binds the unmethylated maternal ICR and protects it from de novo methylation in mouse embryonic stem cells, early development, and oocytes. We further show that this protection occurs independently of Tet-mediated demethylation. A regulatory element containing GZF1 and ZFP57 motifs mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss erases paternal methylation, causing locus maternalization. Gzf1-null mice exhibit postnatal growth retardation, contextualizing cis-deletions of this region and illustrating how imprinting phenotypes may differ when studied through epigenetic perturbation versus genetic deletion. Together, our findings define a reciprocal mechanism by which sequence- and methylation-sensitive factors actively memorize parental epigenetic asymmetry through opposing waves of developmental reprogramming.
Project description:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated imprinted alleles resist de novo methylation remains unclear. Using an allelic methylation reporter at the Dlk1-Dio3 ICR and a genome-wide loss-of-function screen, we identify that the zinc finger protein GZF1 specifically binds the unmethylated maternal ICR and protects it from de novo methylation in mouse embryonic stem cells, early development, and oocytes. We further show that this protection occurs independently of Tet-mediated demethylation. A regulatory element containing GZF1 and ZFP57 motifs mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss erases paternal methylation, causing locus maternalization. Gzf1-null mice exhibit postnatal growth retardation, contextualizing cis-deletions of this region and illustrating how imprinting phenotypes may differ when studied through epigenetic perturbation versus genetic deletion. Together, our findings define a reciprocal mechanism by which sequence- and methylation-sensitive factors actively memorize parental epigenetic asymmetry through opposing waves of developmental reprogramming.
Project description:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated alleles resist de novo methylation remains unclear. Using an allelic Dlk1-Dio3 ICR methylation reporter and genome-wide loss-of-function screening, we identify the zinc finger protein GZF1 that binds the unmethylated maternal ICR and protects it from de novo methylation via a regulatory element containing GZF1 and ZFP57 motifs that mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss results in maternalization. Remarkably, GZF1 protects the unmethylated ICR from de novo methylation in both oocytes and embryos, and its loss leads to perinatal death consistent with paternalization of the maternal allele. Together, our findings establish a reciprocal mechanism that maintains parental epigenetic asymmetry across both imprint establishment and embryonic reprogramming.
Project description:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated alleles resist de novo methylation remains unclear. Using an allelic Dlk1-Dio3 ICR methylation reporter and genome-wide loss-of-function screening, we identify the zinc finger protein GZF1 that binds the unmethylated maternal ICR and protects it from de novo methylation via a regulatory element containing GZF1 and ZFP57 motifs that mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss results in maternalization. Remarkably, GZF1 protects the unmethylated ICR from de novo methylation in both oocytes and embryos, and its loss leads to perinatal death consistent with paternalization of the maternal allele. Together, our findings establish a reciprocal mechanism that maintains parental epigenetic asymmetry across both imprint establishment and embryonic reprogramming.
Project description:Genomic imprinting secures parent-specific gene expression through differential DNA methylation at imprinted control regions (ICRs). However, how unmethylated alleles resist de novo methylation remains unclear. Using an allelic Dlk1-Dio3 ICR methylation reporter and genome-wide loss-of-function screening, we identify the zinc finger protein GZF1 that binds the unmethylated maternal ICR and protects it from de novo methylation via a regulatory element containing GZF1 and ZFP57 motifs that mediates mutually exclusive, methylation-dependent binding. Loss of either factor causes reciprocal imprinting failure: Gzf1 loss induces maternal allele methylation, H3K4me3 depletion, and silencing of maternal transcripts, whereas Zfp57 loss results in maternalization. Remarkably, GZF1 protects the unmethylated ICR from de novo methylation in both oocytes and embryos, and its loss leads to perinatal death consistent with paternalization of the maternal allele. Together, our findings establish a reciprocal mechanism that maintains parental epigenetic asymmetry across both imprint establishment and embryonic reprogramming.