Transcriptional repression from the c-myc P2 promoter by the zinc finger protein ZF87/MAZ

ZF87/MAZ is a zinc finger-containing transcription factor that was cloned based on its ability to bind to a site within the c-myc P2 promoter. However, its role in the control of c-myc transcription has not yet been well established. Here we have analyzed the effect of ZF87/ MAZ overexpression on transcription from the murine c-myc P2 promoter. It was found that when overexpressed in COS cells, ZF87/MAZ significantly represses transcription from P2. The repression is mediated through the ME1a2 element, located at position -86 relative to the P2 transcriptional start site, and is not mediated through either the E2F or the ME1a1 sites. ZF87/ MAZ functions as a true transcriptional repressor since it can repress transcription independently of the c-myc promoter, as part of a fusion with the GAL4 protein. The repressive domain within ZF87/MAZ is located in the amino-terminal half of the protein, a region rich in proline and alanine residues. ZF87/MAZ therefore shares features (i.e. a Pro/Ala-rich region) with those of known transcriptional repressor proteins.