title: Poised chromatin in the mammalian germ line.
abstract: Poised (bivalent) chromatin is defined by the simultaneous presence of histone modifications associated with both gene activation and repression. This epigenetic feature was first observed at promoters of lineage-specific regulatory genes in embryonic stem cells in culture. More recent work has shown that, in vivo, mammalian germ cells maintain poised chromatin at promoters of many genes that regulate somatic development, and that they retain this state from fetal stages through meiosis and gametogenesis. We hypothesize that the poised chromatin state is essential for germ cell identity and function. We propose three roles for poised chromatin in the mammalian germ line: prevention of DNA methylation, maintenance of germ cell identity and preparation for totipotency. We discuss these roles in the context of recently proposed models for germline potency and epigenetic inheritance.
authors.affiliation: Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA leschb@wi.mit.edu.
authors.forename: Bluma J
authors.initials: BJ
authors.lastname: Lesch
authors.affiliation: Whitehead Institute, 9 Cambridge Center, Cambridge, MA 02142, USA Howard Hughes Medical Institute, Whitehead Institute, Cambridge, MA 02142, USA Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Page
mesh_terms: D000818:Animals; D002843:Chromatin / Q000235:genetics / Q000378:metabolism*; D019175:DNA Methylation / Q000502:physiology; D044127:Epigenesis, Genetic / Q000502:physiology*; D005854:Germ Cells / Q000737:chemistry* / Q000166:cytology* / Q000502:physiology; D006657:Histones / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008954:Models, Biological; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology
chemical_list: D002843:Chromatin; D006657:Histones
keywords: Bivalent; Chromatin; Germ cell; Germ line; Pluripotent; Poised