Transcriptional regulation of the human PNRC promoter by NFY in HepG2 cells.

PNRC (proline-rich nuclear receptor co-activator) was previously identified using bovine SF-1 (steroidogenic factor 1) as the bait in a yeast two-hybrid screening of a human mammary gland cDNA expression library. PNRC has been demonstrated to be a novel co-activator for multiple nuclear receptors. To understand the molecular mechanisms that regulate the expression of human PNRC gene, in this study, potential transcriptional start site was determined by 5' RACE analysis. Functional analysis of the 5' flanking region of the human PNRC gene by deletion mutagenesis, transient transfection and luciferase assays revealed that the -123/+27 region is the minimal promoter of the human PNRC gene. Within this promoter region, there is one putative binding site for the transcription factor NFY (nuclear factor Y). EMSA and ChIP analyses demonstrated the specific binding of NFY protein to the human PNRC promoter. Transient transfection and luciferase assays further revealed that over-expression of NFY represses promoter activity of PNRC gene in a dose-dependent manner. These results indicate that the transcription factor NFY specifically binds to promoter region of PNRC and negatively regulates the transcription of the human PNRC gene.