H3 K79 dimethylation marks developmental activation of the beta-globin gene but is reduced upon LCR-mediated high-level transcription.

Publication Type:

Journal Article

Source:

Blood, Volume 112, Issue 2, p.406-14 (2008)

Keywords:

2008, Animals, Basic Sciences Division, Center-Authored Paper, Comparative Medicine Core Facility, Flow Cytometry Core Facility, GENOMICS, Globins, Histones, liver, Locus Control Region, METHYLATION, MICE, Mice, Mutant Strains, Scientific Imaging Core Facility, Shared Resources, Transcription, Genetic, TRANSCRIPTIONAL ACTIVATION

Abstract:

Genome-wide analyses of the relationship between H3 K79 dimethylation and transcription have revealed contradictory results. To clarify this relationship at a single locus, we analyzed expression and H3 K79 modification levels of wild-type (WT) and transcriptionally impaired beta-globin mutant genes during erythroid differentiation. Analysis of fractionated erythroid cells derived from WT/Delta locus control region (LCR) heterozygous mice reveals no significant H3 K79 dimethylation of the beta-globin gene on either allele prior to activation of transcription. Upon transcriptional activation, H3 K79 di-methylation is observed along both WT and DeltaLCR alleles, and both alleles are located in proximity to H3 K79 dimethylation nuclear foci. However, H3 K79 di-methylation is significantly increased along the DeltaLCR allele compared with the WT allele. In addition, analysis of a partial LCR deletion mutant reveals that H3 K79 dimethylation is inversely correlated with beta-globin gene expression levels. Thus, while our results support a link between H3 K79 dimethylation and gene expression, high levels of this mark are not essential for high level beta-globin gene transcription. We propose that H3 K79 dimethylation is destabilized on a highly transcribed template.