Article
- The EMBO Journal (2008) 27, 1255 - 1265
- doi:10.1038/emboj.2008.57
Published online: 20 March 2008
Subject Category:
Epigenetic regulation of TTF-I-mediated promoter–terminator interactions of rRNA genes
Attila Németh1, Sylvain Guibert2, Vijay Kumar Tiwari2, Rolf Ohlsson2 and Gernot Längst1
- Department of Biochemistry III, University of Regensburg, Regensburg, Germany
- Department of Development and Genetics, Uppsala University, Uppsala, Sweden
Correspondence to:
Gernot Längst, Department of Biochemistry III, University of Regensburg, Universitätsstr. 31, Regensburg, 93053, Germany. Tel.: +49 941 9432849; Fax: +49 941 9432474; E-mail: gernot.laengst@vkl.uni-regensburg.de
Received 14 November 2007; Accepted 28 February 2008
Abstract
Ribosomal RNA synthesis is the eukaryotic cell's main transcriptional activity, but little is known about the chromatin domain organization and epigenetics of actively transcribed rRNA genes. Here, we show epigenetic and spatial organization of mouse rRNA genes at the molecular level. TTF-I-binding sites subdivide the rRNA transcription unit into functional chromatin domains and sharply delimit transcription factor occupancy. H2A.Z-containing nucleosomes occupy the spacer promoter next to a newly characterized TTF-I-binding site. The spacer and the promoter proximal TTF-I-binding sites demarcate the enhancer. DNA from both the enhancer and the coding region is hypomethylated in actively transcribed repeats. 3C analysis revealed an interaction between promoter and terminator regions, which brings the beginning and end of active rRNA genes into close contact. Reporter assays show that TTF-I mediates this interaction, thereby linking topology and epigenetic regulation of the rRNA genes.
Keywords:
- chromatin,
- looping,
- nucleolus,
- transcription
