Protein level ratios of CEBPA versus CEBPB may define a dynamic transcriptional switch. (A) Schematic diagram showing the divergent binding patterns and biological roles of the A, B, and C cluster cis-regulatory elements through the first cell cycle of liver regeneration. A previously uncharacterized early resurge of metabolic/homeostatic genes, associated with C cluster regions with binding peaking at 24 h, was observed. (B) Model of a transcriptional switch centered on the relative ratio of CEBPA and CEBPB determining the composition of the CEBP complex pool (homo- or heterodimers). Gene activating or repressive actions are indicated, as well as sets of transcription factors found to be associated with A or C putative enhancers. Metabolic genes are induced and acute phase genes repressed by binding in a CEBPA-high setting (C regions), while the opposite is true for the CEBPB-high setting (B regions). A-type regions are only targeted by CEBPs when the CEBPB form is abundant.
