5-methylcytosine and 5-hydroxymethylcytosine spatiotemporal profiles in the mouse zygote小鼠受精卵5-methylcytosine和5-hydroxymethylcytosine时空配置文件.pdfVIP

5-Methylcytosine and 5-Hydroxymethylcytosine Spatiotemporal Profiles in the Mouse Zygote 1,2 1,2 1,2 ¨ 1,2 Juliette Salvaing *, Tiphaine Aguirre-Lavin , Claire Boulesteix , Gaetan Lehmann , Pascale Debey1,2, Nathalie Beaujean1,2 ´ 1 INRA, UMR1198 Biologie du Developpement et Reproduction, Jouy-en-Josas, France, 2 ENVA, Maisons Alfort, France Abstract Background: In the mouse zygote, DNA methylation patterns are heavily modified, and differ between the maternal and paternal pronucleus. Demethylation of the paternal genome has been described as an active and replication-independent process, although the mechanisms responsible for it remain elusive. Recently, 5-hydroxymethylcytosine has been suggested as an intermediate in this demethylation. Methodology/Principal Findings: In this study, we quantified DNA methylation and hydroxymethylation in both pronuclei of the mouse zygote during the replication period and we examined their patterns on the pericentric heterochromatin using 3D immuno-FISH. Our results demonstrate that 5-methylcytosine and 5-hydroxymethylcytosine localizations on the pericentric sequences are not complementary; indeed we observe no enrichment of either marks on some regions and an enrichment of both on others. In addition, we show that DNA demethylation continues during DNA replication, and is inhibited by aphidicolin. Finally, we observe notable differences in the kinetics of demethylation and hydroxymethylation; in particular, a peak of 5-hydroxymethylcytosine, unrelated to any change in 5-methylcytosine level, is observed after completion of replication. Conclusions/Significan