Identification of a large protein network involved in epigenetic transmission in replicating DNA of embryonic stem cells.
Bottom Line: In particular, we show that the chromatin remodeller HDAC1-NuRD complex is enriched at nascent DNA.Interestingly, an acute block of HDAC1 in ESCs leads to increased acetylation of histone H3 lysine 9 at nascent DNA together with a concomitant loss of methylation.Consistently, in contrast to what has been described in tumour cell lines, these chromatin marks were found to be stable during cell cycle progression of ESCs.
Affiliation: Unit of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden firstname.lastname@example.org.Show MeSH
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Mentions: To investigate whether histone deacetylation and methylation are functionally linked after fork passage in ESCs, we used valproic acid (VPA), a specific inhibitor of class I HDACs with high affinity for HDAC1 (39). VPA holds promise in regenerative medicine, since it has shown to be a potent inducer of pluripotency from somatic cells (40,41). ESCs were treated with a short pulse (30 min) of VPA at low concentration with an EdU pulse during the last 10 min. Nascent chromatin was thereafter purified by iPOND and selected histone modifications were analysed by western blot with specific antibodies (Figure 6A). As expected, acute treatment with VPA led to a marked increase of H3K9Ac levels, both in the input and at nascent DNA (Figure 6A and B). Interestingly, H3K9 mono- and trimethylation was markedly reduced specifically on nascent DNA, in contrast to the input chromatin that remained unaffected. However, the other major repressive histone mark, the methylated lysine 27 at histone H3 and its acetylated form was not significantly affected. These results show that VPA has pronounced effects on the deposition of epigenetic marks during DNA replication, and suggests that in ESCs, HDAC1 could act at nascent DNA by regulating the rapid deacetylation of H3K9 in ESCs, which is necessary for their subsequent methylation during replication.
Affiliation: Unit of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177 Stockholm, Sweden email@example.com.