CAAT ENHANCER BINDING-PROTEINS DIRECTLY MODULATE TRANSCRIPTION FROM THE PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR GAMMA-2 PROMOTER/

The CCAAT/enhancer binding proteins (C/EBPs) and the peroxisome prolif erator-activated receptors (PPARs) together regulate adipogenesis. The current work, uses co-transfection studies to examine the C/EBP depen dence of PPAR gamma 2 transcription. Both C/EBP alpha and C/EBP delta expression vectors activated transcription from a PPAR gamma 2 promote r/luciferase expression vector by 5-6 fold in UMR106 cells. The simult aneous transfection of the C/EBP homologous protein (CHOP) (also known as growth arrest DNA damage protein 153 or gadd153) inhibited this C/ EBP-dependent activation in a concentration dependent manner. The CHOP protein is known to heterodimerize with other C/EBP proteins to form transcriptionally inactive complexes. Mutation of the two C/EBP DNA re cognition elements at -340 bp and -327 bp within the PPAR gamma 2 prom oter reduced the inductive effects of both C/EBP alpha and C/EBP delta . These findings demonstrate that proteins within the C/EBP family dir ectly modulate transcription from the PPAR gamma 2 promoter. (C) 1997 Academic Press.