Analysis on the promoter region of human decidual prolactin gene in the progesterone-induced decidualization and cAMP-induced decidualization of human endometrial stromal cells.

PURPOSE: To elucidate the promoter region of human decidual prolactin (dPRL) gene in the human endometrial stromal cells (ESC).

METHODS

Various segments of the human dPRL promoter that direct the expression of the secreted alkaline phosphatase (SEAP) reporter gene were transfected into human ESC decidualized by estrogen (E) + progesterone (P) or cyclic AMP (cAMP) to identify E + P or cAMP responsive elements.

RESULTS

The region between nucleotides -2038 and -1605 relative to the transcriptional initiation site includes two activator protein-1 (AP-1) sites, which both provided maximal response to E + P or cAMP in decidualized cells. When either AP-1 site was mutated, response in the promoter activity to both E + P or cAMP response showed a decrease compared with control. The region between -310 and -285 that contains consensus-binding sequences for transcription factors of CCAAT/Enhancer-binding proteins (C/EBP) contributed to E + P and cAMP response in decidualized cells. Also, the 5'-flanking region that extends 79 base pairs upstream, including an imperfect cAMP response element (CRE), contributed to E + P and cAMP response. In cells treated with E + P or cAMP for 10 days, mutant of C/EBP-binding site showed an increase in promoter activity comparing to dPRL-2038. In contrast, treatment with PKI showed a decrease in promoter activity in cells treated with E + P or cAMP alone.

CONCLUSIONS

These results suggest that cAMP-induced region of the human dPRL promoter resides between -1862 and -1856, -1703 and -1697, -310 and -285, and that the sequences between -1862 and -1856, -1703 and -1697 of the promoter display E + P-induced promoter activity. Furthermore, the current study indicates that E + P or cAMP cooperatively regulate the dPRL gene transcription through some transcriptional factors such as C/EBP, CREB, and other cofactor(s), and that some repressor(s) or corepressor(s) may be involved in the C/EBP-binding site of the human dPRL promoter.