CAAT/Enhancer Binding Proteins Directly Modulate Transcription from the Peroxisome Proliferator- Activated Receptor γ2 Promoter

Abstract The CCAAT/enhancer binding proteins (C/EBPs) and the peroxisome proliferator-activated receptors (PPARs) together regulate adipogenesis. The current work uses co-transfection studies to examine the C/EBP dependence of PPARγ2 transcription. Both C/EBPα and C/EBPδ expression vectors activated transcription from a PPARγ2 promoter/luciferase expression vector by 5-6 fold in UMR106 cells. The simultaneous 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 recognition elements at −340 bp and −327 bp within the PPARγ2 promoter reduced the inductive effects of both C/EBPα and C/EBPδ. These findings demonstrate that proteins within the C/EBP family directly modulate transcription from the PPARγ2 promoter.