Stability and flexibility of epigenetic gene regulation in mammalian development.
During development, cells start in a pluripotent state, from which they can differentiate into many cell types, and progressively develop a narrower potential. Their gene-expression programmes become more defined, restricted and, potentially, 'locked in'. Pluripotent stem cells express genes that encode a set of core transcription factors, while genes that are required later in development are repressed by histone marks, which confer short-term, and therefore flexible, epigenetic silencing. By contrast, the methylation of DNA confers long-term epigenetic silencing of particular sequences--transposons, imprinted genes and pluripotency-associated genes--in somatic cells. Long-term silencing can be reprogrammed by demethylation of DNA, and this process might involve DNA repair. It is not known whether any of the epigenetic marks has a primary role in determining cell and lineage commitment during development.
Reik
Wolf
W
Laboratory of Developmental Genetics and Imprinting, The Babraham Institute, Cambridge CB22 3AT, UK. wolf.reik@bbsrc.ac.uk
D000818:Animals; D004251:DNA Transposable Elements / Q000235:genetics; D044127:Epigenesis, Genetic / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D020868:Gene Silencing; D018392:Genomic Imprinting; D008322:Mammals / Q000196:embryology* / Q000235:genetics*
D004251:DNA Transposable Elements