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Polycomb Repressive Complexes Restrain the Expression of Lineage-Specific Regulators in Embryonic Stem Cells
Helle F. Jørgensen, Sara Giadrossi, Miguel Casanova, Mitsuhiro Endoh, Haruhiko Koseki, Neil Brockdorff and Amanda G. Fisher
volume 5 | issue 13
1 july 2006Pages: 1411 - 1414
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Stem cells are characterised by a capacity to self renew and generate progeny capable of differentiating along several defined lineage paths. Embryonic Stem (ES) cells are derived from the inner cell mass (ICM) of early-stage embryos and can contribute to all tissues of the developing embryo. Discovering how ES cell pluripotency and lineage induction is achieved is important for understanding normal development and for successfully applying stem cell-based therapies. A series of recent studies have shown that the chromatin profile of ES cells is unusual and have revealed a critical role for the Polycomb Repressive Complexes (PRCs) in maintaining pluripotency. In human and mouse ES cells many genes that encode transcription factors that are required for lineage specification bind PRC2 and carry bivalent (or opposing) histone signatures, being enriched for conventional indicators of active chromatin such as acetylated H3K9 and methylated H3K4, while lying within domains of repressive trimethylated H3K27. Mutant ES cells that lack H3K27 methylation inappropriately expressed these genes showing that PRC2 represses lineage-specific gene programs in ES cells. Here we discuss the implications of these new discoveries and explore the interdependence of PRC1 and PRC2 in regulating lineage-specific gene expression in ES cells.
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDF If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.