Project description:Genomic imprinting is an allele-specific gene expression system important for mammalian development and function. The molecular basis of genomic imprinting is allele-specific DNA methylation 2. While it is well known that the de novo DNA methyltransferases Dnmt3a/b are responsible for the establishment of genomic imprinting, how the methylation mark is erased during primordial germ cell (PGC) reprogramming remains a mystery. Here we report that Tet1 plays a critical role in the erasure of genomic imprinting. We show that despite their identical genotype, progenies derived from mating between Tet1-KO males and wild-type females exhibit a number of variable phenotypes including placental, fetal and postnatal growth defects, and early embryonic lethality. These defects are, at least in part, caused by the dysregulation of imprinted genes, such as Peg10 and Peg3, which exhibit aberrant hypermethylation in the paternal allele of differential methylated regions (DMRs). RNA-seq reveals extensive dysregulation of imprinted genes in the next generation due to paternal functional loss of Tet1. Genome-wide DNA methylation analysis of E13.5 PGCs and sperm derived from Tet1-KO mice reveals hypermethylation of DMRs of imprinted genes in sperm, which can be traced back to PGCs. Dynamics of methylation change in Tet1-affected sites suggested that Tet1 swipes remaining methylation including imprinted genes at late reprogramming stage. We also revealed that Tet1play a role in paternal imprinting erasure in females germline. Thus, our study establishes a critical function for Tet1 in the erasure of genomic imprinting. Genome-wide DNA methylation analysis of E13.5 PGCs from control and Tet1-KO mice
Project description:Genomic imprinting is an allele-specific gene expression system important for mammalian development and function. The molecular basis of genomic imprinting is allele-specific DNA methylation 2. While it is well known that the de novo DNA methyltransferases Dnmt3a/b are responsible for the establishment of genomic imprinting, how the methylation mark is erased during primordial germ cell (PGC) reprogramming remains a mystery. Here we report that Tet1 plays a critical role in the erasure of genomic imprinting. We show that despite their identical genotype, progenies derived from mating between Tet1-KO males and wild-type females exhibit a number of variable phenotypes including placental, fetal and postnatal growth defects, and early embryonic lethality. These defects are, at least in part, caused by the dysregulation of imprinted genes, such as Peg10 and Peg3, which exhibit aberrant hypermethylation in the paternal allele of differential methylated regions (DMRs). RNA-seq reveals extensive dysregulation of imprinted genes in the next generation due to paternal functional loss of Tet1. Genome-wide DNA methylation analysis of E13.5 PGCs and sperm derived from Tet1-KO mice reveals hypermethylation of DMRs of imprinted genes in sperm, which can be traced back to PGCs. Dynamics of methylation change in Tet1-affected sites suggested that Tet1 swipes remaining methylation including imprinted genes at late reprogramming stage. We also revealed that Tet1play a role in paternal imprinting erasure in females germline. Thus, our study establishes a critical function for Tet1 in the erasure of genomic imprinting. Genome-wide DNA methylation analysis of sperm derived from control and Tet1-KO mice
Project description:RRBS was used to analyse global imprinting gene methylation pattern of offspring from the in vitro derived spermatids like cells and normal control Global imprinting gene methylation pattern comparision of two offspring (one male and one female) from the in vitro derived spermatids like cells and two normal control mice (one male and one female)
Project description:DNA demethylation of paternal genome in zygotes takes place in various mammals including mice and human. Recent studies have revealed that this is achieved through Tet3-mediated iterative oxidation of 5-methylcytosine (5mC) coupled with replication-dependent dilution. Tet3-mediated paternal DNA demethylation is believed to be required for mouse development given that Tet3 heterozygous embryos, derived by fertilizing Tet3 knockout (KO) oocytes with wild-type (WT) sperms, exhibit 5mC oxidation defects and embryonic sublethality, Here we demonstrate that the sublethality phenotype of the maternal KO mice is caused by haploinsufficiency of Tet3, but not by defective paternal 5mC oxidation. We found that Tet3 heterozygous mice derived from crosses of heterozygous father or mother with WT mice also exhibit sublethality phenotype similarly to Tet3 maternal KO mice. Importantly, embryos reconstituted with WT paternal nuclei that bypassed 5mC oxidation develop to term and grow to adulthood normally. Genome-scale DNA methylation analysis of the maternal KO zygotes and blastocysts demonstrated that hypermethylation caused by the depletion of maternal Tet3 is largely diminished by the blastocyst stage. Our study thus not only demonstrates that Tet3-mediated paternal 5mC oxidation is dispensable for mouse development but also suggests the existence of a compensation mechanism in preimplantation embryos that can compensate for the defective 5mC oxidation in zygotes. This data set includes RRBS data of wild-type and maternal Tet3 KO zygotes and blastocysts (C57BL/6J x CAST/EiJ)
Project description:With the exception of imprinted genes and certain repeats, DNA methylation is globally erased during pre-implantation development. Recent studies have suggested that Tet3-mediated oxidation of 5-methylcytosine (5mC) and DNA replication-dependent dilution both contribute to global paternal DNA demethylation, but demethylation of the maternal genome occurs via replication. Here we present genome-scale DNA methylation maps for both the paternal and maternal genomes of Tet3-depleted and/or DNA replication-inhibited zygotes. In both genomes, we found that inhibition of DNA replication blocks DNA demethylation independently from Tet3 function, and that Tet3 facilitates DNA demethylation by coupling with DNA replication. For both, our data indicate that replication-dependent dilution is the major contributor to demethylation, but Tet3 plays an important role, particularly at certain loci. Our study therefore both defines the respective functions of Tet3 and DNA replication in paternal DNA demethylation and reveals an unexpected contribution of Tet3 to demethylation of the maternal genome. In this data set, we include RRBS data of manually isolated paternal and maternal pronuclei from both WT and Tet3 CKO zygotes with or without aphidicolin treatment
Project description:We performed calibrated total RNAseq on mESC (Scc1-AID) for both untreated and treated cells with a 6-hour auxin exposure to assess the effects of cohesin removal on gene expression. For calibration purposes 2x10ˆ6 Drosophila SG4 cells were spiked in.
Project description:Differential gene transcription enables development and homeostasis in all animals and is regulated by two major classes of distal cis-regulatory DNA elements (CREs), enhancers and silencers. While enhancers have been thoroughly characterized, the properties and mechansisms of silencers remain largely unknown. By an unbiased genome-wide functional screen in Drosophila melanogaster S2 cells, we discover a class of silencers that bind one of three transcription factors (TFs) and are generally not included in chromatin-defined CRE catalogs, as they mostly lack detectable DNA accessibility. The silencer-binding TF CG11247, which we term Saft, safeguards cell fate decisions in vivo and functions via a highly-conserved domain we term ZAC and the corepressor G9a, independently of G9a’s H3K9-methyltransferase activity. Overall, our identification of silencers with unexpected properties and mechanisms has important implications for the understanding and future study of repressive CREs, as well as the functional annotation of animal genomes.
Project description:Genomic imprinting is an allele-specific gene expression system important for mammalian development and function. The molecular basis of genomic imprinting is allele-specific DNA methylation 2. While it is well known that the de novo DNA methyltransferases Dnmt3a/b are responsible for the establishment of genomic imprinting, how the methylation mark is erased during primordial germ cell (PGC) reprogramming remains a mystery. Here we report that Tet1 plays a critical role in the erasure of genomic imprinting. We show that despite their identical genotype, progenies derived from mating between Tet1-KO males and wild-type females exhibit a number of variable phenotypes including placental, fetal and postnatal growth defects, and early embryonic lethality. These defects are, at least in part, caused by the dysregulation of imprinted genes, such as Peg10 and Peg3, which exhibit aberrant hypermethylation in the paternal allele of differential methylated regions (DMRs). RNA-seq reveals extensive dysregulation of imprinted genes in the next generation due to paternal functional loss of Tet1. Genome-wide DNA methylation analysis of E13.5 PGCs and sperm derived from Tet1-KO mice reveals hypermethylation of DMRs of imprinted genes in sperm, which can be traced back to PGCs. Dynamics of methylation change in Tet1-affected sites suggested that Tet1 swipes remaining methylation including imprinted genes at late reprogramming stage. We also revealed that Tet1play a role in paternal imprinting erasure in females germline. Thus, our study establishes a critical function for Tet1 in the erasure of genomic imprinting. Gene expression analysis of E9.5 embryos
Project description:Active DNA demethylation in mammals involves TET-mediated iterative oxidation of 5-methylcytosine (5mC)/5-hydroxymethylcytosine (5hmC) and subsequent excision repair of highly oxidized cytosine bases 5-formylcytosine (5fC)/5-carboxylcytosine (5caC) by Thymine DNA glycosylase (TDG). However, quantitative and high-resolution analysis of active DNA demethylation activity remains challenging. Here we describe M.SssI methylase-assisted bisulfite sequencing (MAB-seq), a method that directly maps 5fC/5caC at single-base resolution. Genome-wide MAB-seq allows systematic identification of 5fC/5caC in Tdg-depleted embryonic stem cells, thereby generating a base-resolution map of active DNA demethylome. A comparison of 5fC/5caC and 5hmC distribution maps indicates that catalytic processivity of TET enzymes correlates with local chromatin accessibility. MAB-seq also reveals strong strand asymmetry of active demethylation within palindromic CpGs. Integrating MAB-seq with other base-resolution mapping methods enables quantitative measurement of cytosine modification states at key transitioning steps of active demethylation pathway, and reveals a regulatory role of 5fC/5caC excision repair in active DNA demethylation cascade. Analysis of 5fC/5caC excision repair-dependent active DNA demethylome by MAB-seq in mouse embryonic stem cells.