Trim28 Is Required for Epigenetic Stability During Mouse Oocyte to Embryo Transition

Trimprinting the Genome Reprogramming the parental genomes during the oocyte-to-embryo transition requires highly controlled epigenetic mechanisms. Although resetting the genome to a ground state is essential, conservation of inheritable marks is equally important. Now, Messerschmidt et al. (p. 1499 ) demonstrate that maternal deletion of the epigenetic modifier Trim28 in mice results in a strongly variable, yet ultimately embryonic, lethal phenotype. Aberrant loss of DNA methylation at imprinting control regions and thus partial loss of epigenetic memory was responsible for the phenotype. The stochastic time and mode of embryonic death reflect the exquisitely balanced interplay of maternal and zygotic factors in the early mammalian embryo.