Epigenetic asymmetry in the mammalian zygote and early embryo: relationship to lineage commitment?
Philos Trans R Soc Lond B Biol Sci
; 358(1436): 1403-9; discussion 1409, 2003 Aug 29.
Article
em En
| MEDLINE
| ID: mdl-14511488
ABSTRACT
Epigenetic asymmetry between parental genomes and embryonic lineages exists at the earliest stages of mammalian development. The maternal genome in the zygote is highly methylated in both its DNA and its histones and most imprinted genes have maternal germline methylation imprints. The paternal genome is rapidly remodelled with protamine removal, addition of acetylated histones, and rapid demethylation of DNA before replication. A minority of imprinted genes have paternal germline methylation imprints. Methylation and chromatin reprogramming continues during cleavage divisions, but at the blastocyst stage lineage commitment to inner cell mass (ICM) or trophectoderm (TE) fate is accompanied by a dramatic increase in DNA and histone methylation, predominantly in the ICM. This may set up major epigenetic differences between embryonic and extraembryonic tissues, including in X-chromosome inactivation and perhaps imprinting. Maintaining epigenetic asymmetry appears important for development as asymmetry is lost in cloned embryos, most of which have developmental defects, and in particular an imbalance between extraembryonic and embryonic tissue development.
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Base de dados:
MEDLINE
Assunto principal:
Blastocisto
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Diferenciação Celular
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Impressão Genômica
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Regulação da Expressão Gênica no Desenvolvimento
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Linhagem da Célula
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Metilação de DNA
Limite:
Animals
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article