CANCELLED Plasticity of X-inactivation in cell lineages of the early embryo
17/09/2013 - Room M203/V1 26 at 14:00 - Pink Seminar
(EMBL Monterotondo )
In somatic tissues of eutherian female mammals the process of random X-chromosome equalizes the dosage of X-linked genes between the sexes by a process of epigenetic silencing. Many experiments have demonstrated the extreme stability of this inactivation which has been attributed at least in part to its complexity and supposed built in redundancy. Compared with this form of X-inactivation, inactivation in metatherians and the imprinted inactivation of the paternal X present in the mouse placenta, appears relatively unstable. We wished to characterise more closely whether this instability extends to all murine extra-embryonic tissues and whether this instability is already present in placental progenitor cells prior to differentiation towards lineage specific cell types. Evidence will be presented for extensive reactivation/X-inactivation cycles affecting cells of the trophoblastic lineage and apparent major differences in X-inactivation not only between X-inactivation in somatic tissues but also between different extra-embryonic lineages. Such “epigenetic” states may underlie the plasticity of TS cells and predispose specific genes to relaxed regulation in specific subtypes of placental cells.