Project description:Primordial germ cells (PGCs) are fate restricted to differentiate into gametes in vivo. However when removed from their embryonic niche PGCs undergo reversion to generate pluripotent embryonic germ cells (EGCs) in vitro. One of the major differences between EGCs and embryonic stem cells (ESCs) involves variable methylation at imprinting control centers (ICCs), a phenomenon that is poorly understood. In the current study we show that reverting PGCs to EGCs involves ICC methylation erasure, which remain stably hypomethylated at Snrpn, Igf2r and Kcnqot1. In contrast, the H19/Igf2 ICC undergoes almost complete de novo remethylation. Using the same approach for PGCs differentiated in vitro from ESCs we show that the Snrpn ICC is erased however the hypomethylated state is highly unstable. We also discovered that when the H19/Igf2 ICC is abnormally hypermethylated in ESCs, ICC methylation is not erased with differentiation into PGCs. This highlights the importance of not only launching germline differentiation with correctly methylated ESC lines but also the need to better stabilize the hypomethylated state in the in vitro derivatives following ICC erasure.
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: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: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.
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.
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.
Project description:Genome-wide DNA demethylation, including the erasure of genome imprints, in primordial germ cells (PGCs), is critical as a first step for creating the totipotent epigenome in the germ line. Here, we provide evidence that contrary to the prevailing model involving active DNA demethylation, imprint erasure in mouse PGCs occurs in a manner consistent with replication-coupled passive DNA demethylation: PGCs erase imprints during their rapid proliferation with little de novo as well as maintenance DNA methylation potential and no major chromatin alterations. Our findings necessitate the re-evaluation of and provide novel insights into the mechanism of genome-wide DNA demethylation in PGCs. We performed expression analysis of primordial germ cells (PGCs) at embryonic days 10.5-13.5. Because the number of PGCs available at these stages were low, cDNAs were amplified by the method that we previously published (Kurimoto et al. 2006, NAR 34: e42 (PMID 16547197)). To include analysis of PGC gene expression at E9.5, we re-normalized the data from our E9.5 PGC samples (GSM744103, GSM744104) from our previous publication (Hayashi et al., 2011, Cell 146: 519-32 (PMD 21820164)) together with the data from this submission.
Project description:Previous studies have suggested an erasure of DNA methylation is required to develop the stem cells in the morula embryo. An exception involves imprinted genes that escape this DNA methylation erasure. Transgenerational differential DNA methylation regions (DMRs) have been speculated to also escape this erasure. The current study was designed to assess if morula embryos escape erasure of DDT (dichloro-diphenyl-trichloroethane)-induced transgenerational sperm DMRs. Observations demonstrate that the transgenerational sperm DMR sites are not erased, so are imprinted-like DMR sites. Interestingly, we also found that the majority of low-density CpG genomic sites had a significant increase in DNA methylation in the morula embryo compared to sperm. The general erasure of DNA methylation during embryogenesis appears applicable for high-density CpG islands, but not low-density CpG deserts.