title: Dynamic reprogramming of chromatin: paradigmatic palimpsests and HES factors.
abstract: Temporal and spatial control of transcription in development is dictated to a great extent by transcriptional repressors. Some repressor complexes, such as Polycomp-group proteins, induce relatively long-term non-permissive states, whereas others such as hairy/enhancer of split (HES) family repressors are linked to dynamically modulated chromatin states associated with cycling expression of target genes. The mode of action and specificity of repressors involved in mediating this latter form of epigenetic control are unknown. Oscillating expression of HES repressors controlled by signaling pathways such as Notch suggests that the entire ensemble of HES-associated co-repressors and histone modifying complexes readily cycle on and off genes. Dynamic interactions between these factors and chromatin seem to be crucial in maintaining multipotency of progenitor cells, but the significance of such interactions in more differentiated cells is less well understood. We discuss here how genome-wide analyses and real-time gene expression measurements of HES regulated genes can help decipher the detailed mechanisms and biological importance of highly dynamic transcriptional switching mediated by epigenetic changes.
authors.affiliation: Genetics Program, Michigan State University , East Lansing, MI, USA.
authors.forename: Kurtulus
authors.initials: K
authors.lastname: Kok
authors.affiliation: Genetics Program, Michigan State University , East Lansing, MI, USA ; Department of Biochemistry and Molecular Biology, Michigan State University , East Lansing, MI, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Arnosti
keywords: HES; chromatin; hairy; oscillatory gene expression; repression