13 February 2015
Gordon Hager
Laboratory of Receptor Biology and Gene Expression
National Cancer Institute
Transcription factors (TFs) regulate gene expression by interacting with chromatinized DNA response elements (REs). Access to these elements is dramatically restricted by chromatin organization, and modification of the nucleoprotein structure to allow factor binding is a key feature of cell selective gene regulation. Local transitions in chromatin access [often characterized as DNaseI hypersensitive sites (DHSs)] are often associated with the action of ATP-dependent chromatin remodeling proteins; ATP-dependent remodeling may be a universal feature of these transitions. These processes are highly dynamic, often with factor/template interactions persisting only for a few seconds. A model (Dynamic Assisted Loading) has been proposed for regulatory element function that integrates critical observations from live cell imaging, genome wide characterization of binding factors, and the biochemistry of remodeling complexes.