Shovlin, T. C., Durcova-Hills, G., Surani, A. & McLaren, A. Heterogeneity in imprinted methylation patterns of pluripotent embryonic germ cells derived from pre-migratory mouse germ cells. Dev. Biol. 313, 674-681

The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.
Developmental Biology (Impact Factor: 3.55). 02/2008; 313(2):674-81. DOI: 10.1016/j.ydbio.2007.11.007
Source: PubMed


Pluripotent stem cells, termed embryonic germ (EG) cells, have been generated from both human and mouse primordial germ cells (PGCs). Like embryonic stem (ES) cells, EG cells have the potential to differentiate into all germ layer derivatives and may also be important for any future clinical applications. The development of PGCs in vivo is accompanied by major epigenetic changes including DNA demethylation and imprint erasure. We have investigated the DNA methylation pattern of several imprinted genes and repetitive elements in mouse EG cell lines before and after differentiation. Analysed cell lines were derived soon after PGC specification, "early", in comparison with EG cells derived after PGC colonisation of the genital ridge, "late" and embryonic stem (ES) cell lines, derived from the inner cell mass (ICM). Early EG cell lines showed strikingly heterogeneous DNA methylation patterns, in contrast to the uniformity of methylation pattern seen in somatic cells (control), late EG cell and ES cell lines. We also observed that all analysed XX cell lines exhibited less methylation than XY. We suggest that this heterogeneity may reflect the changes in DNA methylation taking place in the germ cell lineage soon after specification.

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Available from: Gabriela Durcova-Hills, Jan 20, 2014
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    • "More detailed analyses of similarities and differences in DNA methylation have been performed only between ES cells and PGC-derived EG cell lines. Similarly to PGCs, EG cells derived from 11.5–12.5 dpc PGCs were shown to be grossly hypomethylated (mainly in EG cells with both active XX, [68]) and possess strong demethylation activity [69]. As for methylation of imprinted genes, EG cells derived soon after PGC specification (early EG cells) showed heterogeneous DNA methylation patterns in comparison with EG cells derived after PGC colonisation of the gonadal ridges (late EG cells) which were uniformly hypomethylated at these sites with the expected exception of H19 locus [68]. "
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    ABSTRACT: The unique capability of germ cells to give rise to a new organism, allowing the transmission of primary genetic information from generation to generation, depends on their epigenetic reprogramming ability and underlying genomic totipotency. Recent studies have shown that genome-wide epigenetic modifications, referred to as "epigenetic reprogramming", occur during the development of the gamete precursors termed primordial germ cells (PGCs) in the embryo. This reprogramming is likely to be critical for the germ line development itself and necessary to erase the parental imprinting and setting the base for totipotency intrinsic to this cell lineage. The status of genome acquired during reprogramming and the associated expression of key pluripotency genes render PGCs susceptible to transform into pluripotent stem cells. This may occur in vivo under still undefined condition, and it is likely at the origin of the formation of germ cell tumors. The phenomenon appears to be reproduced under partly defined in vitro culture conditions, when PGCs are transformed into embryonic germ (EG) cells. In the present paper, I will try to summarize the contribution that epigenetic modifications give to nuclear reprogramming in mouse PGCs.
    Full-text · Article · Sep 2011
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    • "The same is the case is for embryonic germ (EG) cells, which are derived from PGCs. Interestingly, EG cells derived from late PGCs also erase their autosomal imprints, while ES cells retain them (Shovlin et al. 2008), demonstrating differences in reprogramming capacity of different pluripotent stem cell types. When fused with female differentiated cells, factors present in ES and EG cells reprogram the somatic genome to a pluripotent state causing reactivation of the somatic inactive X-chromosome (Tada et al. 1997, 2001). "
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    ABSTRACT: X-chromosome inactivation is an epigenetic hallmark of mammalian development. Chromosome-wide regulation of the X-chromosome is essential in embryonic and germ cell development. In the male germline, the X-chromosome goes through meiotic sex chromosome inactivation, and the chromosome-wide silencing is maintained from meiosis into spermatids before the transmission to female embryos. In early female mouse embryos, X-inactivation is imprinted to occur on the paternal X-chromosome, representing the epigenetic programs acquired in both parental germlines. Recent advances revealed that the inactive X-chromosome in both females and males can be dissected into two elements: repeat elements versus unique coding genes. The inactive paternal X in female preimplantation embryos is reactivated in the inner cell mass of blastocysts in order to subsequently allow the random form of X-inactivation in the female embryo, by which both Xs have an equal chance of being inactivated. X-chromosome reactivation is regulated by pluripotency factors and also occurs in early female germ cells and in pluripotent stem cells, where X-reactivation is a stringent marker of naive ground state pluripotency. Here we summarize recent progress in the study of X-inactivation and X-reactivation during mammalian reproduction and development as well as in pluripotent stem cells.
    Full-text · Article · Jun 2011 · Human Genetics
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    • "PGCs also differ from EG cells in the expression of several genes associated with pluripotency (Durcova-Hills et al., 2008). Moreover EG cells do not reflect the methylation status of imprinted genes of those in the PGCs from which they were derived (Hajkova et al., 2002; Durcova-Hills et al., 2001; Labosky et al., 1994; Tada et al., 1998; Shovlin et al., 2008). Since EG cells are not an appropriate source of cells to study the biology of PGCs there has been a great interest in finding new sources or techniques to derive PGCs in vitro. "
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    ABSTRACT: Embryonic stem (ES) cells, derived from pre-implantation embryo, embryonic germ (EG) cells, derived from embryonic precursors of gametes, primordial germ cells (PGCs), can differentiate into any cell type in the body. Moreover, ES cells have the capacity to differentiate into PGCs in vitro. In the present study we have shown the differentiation capacity of six EG cell lines to form PGCs in vitro, in comparison to ES cells. Cell lines were differentiated via embryoid body (EB) formation using the co-expression of mouse vasa homolog (Mvh) and Oct-4 to identify newly formed PGCs in vitro. We found an increase of PGC numbers in almost all analysed cell lines in 5-day-old EBs, thus suggesting that EG and ES cells have similar efficiency to generate PGCs. The addition of retinoic acid confirmed that the cultures had attained a PGC-like identity and continued to proliferate. Furthermore we have shown that the expression pattern of Prmt5 and H3K27me3 in newly formed PGCs is similar to that observed in embryonic day E11.5 PGCs in vivo. By co-culturing EBs with Chinese hamster ovary (CHO) cells some of the PGCs entered into meiosis, as judged by Scp3 expression. The derivation of germ cells from pluripotent stem cells in vitro could provide an invaluable model system to study both the genetic and epigenetic programming of germ cell development in vivo.
    Full-text · Article · Sep 2009 · Differentiation
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