Submission Number: SEA-4-11-20

Abstract Number: 4

TRANSACTIVATION OF THE OVINE PLACENTAL LACTOGEN GENE IS STIMULATED BY PUR ALPHA.

Sean W Limesand*, Kimberly M Jeckel and Russell V Anthony*

Department of Physiology, Colorado State University, Fort Collins, CO ¹

Abstract:
Placental lactogen (PL) is thought to alter maternal metabolism to increase the pool of nutrients available for the fetus and stimulate nutrient uptake. The ovine (o) PL gene is expressed in chorionic binucleate cells (BNC) and has cis-acting elements located within the proximal 124 base pair (bp) promoter region capable of regulating trophoblast-cell specific activity in a human choriocarcinoma cell line (BeWo). DNase I protection assays identified protein-DNA interactions with ovine BNC nuclear extracts between -95/-123 bp, and mutational analysis in BeWo cells revealed a novel cis-element that was functional. Characterization of this cis-element in BeWo and BNC nuclear extracts identified a specific interaction with the nucleotide sequence CCAGCA (-110/-105; o110) and southwestern analysis identified a nuclear protein in BeWo cells with an apparent Mr of 41,000. Screening an ovine placental expression library identified positive plaques encoding a DNA binding protein interacting with this site, which were purified to homogeneity. Six of the eleven clones purified were homologous to each other by southern hybridization. The nucleotide sequence of these clones shared similarity with the human (97%) and mouse (95%) Pur alpha single-stranded DNA binding protein. The Pur alpha-o110 interaction was confirmed by electrophoretic mobility-supershift assays with BNC and BeWo nuclear extracts. Transactivation of the -124 to +16 region of the oPL gene was enhanced by the ovine Pur alpha expression vector. These data are the first to identify Pur alpha as a placental trans-acting factor, which stimulates expression of the oPL promoter, through a novel cis-element. Supported by USDA Grant 97-35206-5092.

Keywords: Placental Lactogen Gene, Transcription factors

This abstract is being presented at: 2:15 PM in session:
SESSION I: TRAINEE RESEARCH COMPETITION