Difference between random and imprinted X inactivation in common voles.
Dementyeva EV., Shevchenko AI., Anopriyenko OV., Mazurok NA., Elisaphenko EA., Nesterova TB., Brockdorff N., Zakian SM.
During early development in female mammals, most genes on one of the two X-chromosomes undergo transcriptional silencing. In the extraembryonic lineages of some eutherian species, imprinted X-inactivation of the paternal X-chromosome occurs. In the cells of the embryo proper, the choice of the future inactive X-chromosome is random. We mapped several genes on the X-chromosomes of five common vole species and compared their expression and methylation patterns in somatic and extraembryonic tissues, where random and imprinted X-inactivation occurs, respectively. In extraembryonic tissues, more genes were expressed on the inactive X-chromosome than in somatic tissues. We also found that the methylation status of the X-linked genes was always in accordance with their expression pattern in somatic, but not in extraembryonic tissues. The data provide new evidence that imprinted X-inactivation is less complete and/or stable than the random form and DNA methylation contributes less to its maintenance.