The expression of imprinted genes is controlled by allele-specific epigenetic modifications of Imprinting Control Regions (ICRs). It has been previously demonstrated that the binding at ICRs of a multiprotein complex including ZFP57 and its co-factor KAP1 is necessary for maintaining DNA methylation and trimethylation of Histone 3 Lysine 9 (H3K9me3) in mouse embryonic stem cells (mESC). We now have further investigated the role of ZFP57 by determining its genome-wide binding in different mESC lines and studied interplay with epigenetic marks in Zfp57 knockout cells. When ZFP57 is lost there was complete demethylation and a much more extensive and wider loss of H3K9me3 at all the ICRs. We also observed the enrichment of H3K4me3 mark at these sites. Apart ICRs, ZFP57 also binds other regions, mostly intergenic, that we grouped as Non-ICRs. Upon Zfp57 removal, these regions were much more reluctant in loss of methylation and showed high enrichment of H3K4me1 mark. Our data demonstrate that ratio of H3K4me1/H3K4me3 is much lower in ICRs when compared to Non-ICRs, suggesting that the first are marked by a typical promoter epigenome and the latter by an histone modification (H3K4me1) that usually marks enhancers. Moreover, locus-specific analysis in DNMTs TKO cells demonstrates that enrichments of these marks is independent on DNA methylation. Our data support a model by which recruitment of heterochromatin marks by Zfp57 allows to counteract the activation of promoters at imprinted loci and of enhancers at many non-imprinted loci in undifferentiated ESCs.
Genome-wide analysis of Zfp57-mediated epigenetic control at imprinted and non imprinted loci in mouse embryonic stem cells
Annalisa Fico;Claudia Angelini;Giovanna Grimaldi;Andrea Riccio
2015
Abstract
The expression of imprinted genes is controlled by allele-specific epigenetic modifications of Imprinting Control Regions (ICRs). It has been previously demonstrated that the binding at ICRs of a multiprotein complex including ZFP57 and its co-factor KAP1 is necessary for maintaining DNA methylation and trimethylation of Histone 3 Lysine 9 (H3K9me3) in mouse embryonic stem cells (mESC). We now have further investigated the role of ZFP57 by determining its genome-wide binding in different mESC lines and studied interplay with epigenetic marks in Zfp57 knockout cells. When ZFP57 is lost there was complete demethylation and a much more extensive and wider loss of H3K9me3 at all the ICRs. We also observed the enrichment of H3K4me3 mark at these sites. Apart ICRs, ZFP57 also binds other regions, mostly intergenic, that we grouped as Non-ICRs. Upon Zfp57 removal, these regions were much more reluctant in loss of methylation and showed high enrichment of H3K4me1 mark. Our data demonstrate that ratio of H3K4me1/H3K4me3 is much lower in ICRs when compared to Non-ICRs, suggesting that the first are marked by a typical promoter epigenome and the latter by an histone modification (H3K4me1) that usually marks enhancers. Moreover, locus-specific analysis in DNMTs TKO cells demonstrates that enrichments of these marks is independent on DNA methylation. Our data support a model by which recruitment of heterochromatin marks by Zfp57 allows to counteract the activation of promoters at imprinted loci and of enhancers at many non-imprinted loci in undifferentiated ESCs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
