Cloning and characterization of the 5'-flanking region of the human growth hormone secretagogue receptor gene

Recently, the growth hormone secretagogue receptor (GHS-R) cDNA has been isolated from the pituitary and hypothalamus. To evaluate the regulation of human (h) GHS-R gene expression, we cloned the hGHS-R gene containing the 5'-flanking region of 0.6-2.9 kilobase pairs. Analysis of the hGHS-R transcripts with 5'-rapid amplification of cDNA ends suggested that the putative transcription initiation site was approximately -453 base pairs upstream of the translation initiation site (+1). There is no typical TATA, CAAT, or GC box but an initiator-like sequence and putative binding sites for several transcription factors around the putative transcription start site. The 5'-flanking region inserted into a luciferase reporter vector had promoter activity in GH3 cells but had activity indistinguishable from background in HeLa or EP1 cells. The hGHS-R promoter activity in GH3 cells increased by deletion of nucleotides from -1224 to -734, whereas it was decreased by further deletion from -734 to -608. Knowledge of the promoter region of the hGHS-R gene will facilitate elucidation of its transcriptional control.