Promoter analysis of human cholecystokinin type-A receptor gene.

Background. We have previously shown that polymorphism in the promoter region of the human cholecystokinin type-A receptor ( CCKAR) gene is a genetic factor affecting obesity. However, there have not yet been any reports of analysis of the promoter activity of CCKAR genes, and thus almost nothing is known about CCKAR transcriptional regulation. Methods. Using STC-1 cells, an enteroendocrine tumor cell line, we measured the promoter activity of the human CCKAR gene by a transient transfection method. Results. We showed that STC-1 cells expressed CCKAR as well as its peptide-ligand, CCK. Analysis of a series of 5'-deleted promoter constructs showed that the proximal 622-base region upstream from the initiation site, which contained two GC-box motifs, was important as a regulatory region for the transcriptional activity. However, no significant differences were found for the promoter activities of polymorphic promoter constructs. Conclusions. These results suggest that the reported polymorphism may not play a role in transcriptional regulation.