Cloning and Characterization of the 5′-Flanking Region of the Human Prolactin-Releasing Peptide Receptor Gene

Abstract

Recently a novel peptide which specifically stimulates the secretion of prolactin (PRL) was found and named PRL-releasing peptide (PrRP). To evaluate the regulation of human (h) PrRP-receptor (PrRP-R) gene expression, we cloned the 5′-flanking region of the hPrRP-R gene and determined the nucleotide sequence of 4.0 kilobase pairs (kb) upstream from the translation start site. Analysis of the hPrRP-R transcripts by means of 5′-rapid amplification of cDNA ends suggested that the hPrRP-R gene had multiple transcription start sites between −429 and −365 from the translation start site. There is no typical TATA or CAAT but a GC box and putative binding sites for several transcription factors including Pit-1 and pituitary homeobox 1 (Ptx1). However, transient transfection studies using a luciferase reporter gene demonstrated that 5′-flanking region exerts promoter activity in several non-pituitary cell lines as well as in GH3 cells. The GC box located from −467 to −457 was identified as an important region for the basal expression of the hPrRP-R gene. Knowledge of the promoter region of the hPrRP-R gene, which was obtained in the present study, will facilitate the clarification of its transcriptional regulation.