Molecular cloning of tef-p, a tea/atts domain transcr1ptional factor from human placenta

Placental expression of the human chorionic somatomammotropin (hCS) gene is controlled by an enhancer (CSEn) containing SV40-related GT-IIC and Sphl/II enhansons. Although SV40 enhancer function is thought to be controlled by transcription enhancer factor-1 (TEF-1) binding to these enhansons, TEF-1 is associated with negative regulation of CSEn and hCS promoter function in choriocarcinoma (BeWo) cells and enhancer activity is controlled by another factor that binds GT-IIC and Sphl/II binding motifs with similar specificity as TEF1. We have cloned several TEF-1 homologs using nested, degenerate PCR primers corresponding to two highly conserved domains in TEF-1 homologs: the TEA/ATTS DNA-binding domain and a carboxy terminal region. PCR amplification of a human placental cDNA library, followed by cloning and sequencing of the amplification products yielded several novel TEF-1 -related cDNAs. The full open reading frame of one clone, TEF-P is about 70% identical with TEF-1. Northern blot analysis indicates that TEF-P mRNA is enriched in placental tissue and BeWo cells. The in vitro-generated 55 kDa peptide binds specifically to GTIIC and Sphl/II oligonucleotides. Co-transfection of TEF-P expression vectors with CSEn-containing reporter genes resulted in increased enhancer activity in BeWo cells (4-to 8-fold). These data indicate that TEF-P is involved in the control of CSEn enhancer function in placenta.