| First Author | Kalantry S | Year | 2006 |
| Journal | Nat Cell Biol | Volume | 8 |
| Issue | 2 | Pages | 195-202 |
| PubMed ID | 16415857 | Mgi Jnum | J:129406 |
| Mgi Id | MGI:3769211 | Doi | 10.1038/ncb1351 |
| Citation | Kalantry S, et al. (2006) The Polycomb group protein Eed protects the inactive X-chromosome from differentiation-induced reactivation. Nat Cell Biol 8(2):195-202 |
| abstractText | The Polycomb group (PcG) encodes an evolutionarily conserved set of chromatin-modifying proteins that are thought to maintain cellular transcriptional memory by stably silencing gene expression. In mouse embryos that are mutated for the PcG protein Eed, X-chromosome inactivation (XCI) is not stably maintained in extra-embryonic tissues. Eed is a component of a histone-methyltransferase complex that is thought to contribute to stable silencing in undifferentiated cells due to its enrichment on the inactive X-chromosome in cells of the early mouse embryo and in stem cells of the extra-embryonic trophectoderm lineage. Here, we demonstrate that the inactive X-chromosome in Eed(-/-) trophoblast stem cells and in cells of the trophectoderm-derived extra-embryonic ectoderm in Eed(-/-) embryos remain transcriptionally silent, despite lacking the PcG-mediated histone modifications that normally characterize the facultative heterochromatin of the inactive X-chromosome. Whereas undifferentiated Eed(-/-) trophoblast stem cells maintained XCI, reactivation of the inactive X-chromosome occurred when these cells were differentiated. These results indicate that PcG complexes are not necessary to maintain transcriptional silencing of the inactive X-chromosome in undifferentiated stem cells. Instead, PcG proteins seem to propagate cellular memory by preventing transcriptional activation of facultative heterochromatin during differentiation. |
