Promoter analysis of a medaka fish intestinal guanylyl cyclase gene

We characterized the promoter activity of a medaka fish intestinal guanylyl cyclase gene, OlGC6, by assay of enzyme activity in response to various promoter-luciferase fusion gene constructs introduced into CACO-2 cells and medaka fish embryos. A transient transfection assay of the various fusion gene constructs showed that the nucleotides between -98 and -89 in the 5'-flanking region of the OlGC6 gene are essential for transcription of the OlGC6 gene in CACO-2, and that the OlGC6 gene fragment between -98 and +50 is sufficient to drive gene expression in the medaka fish intestine. An electrophoretic mobility shift assay and ultraviolet (UV) cross-linking experiments demonstrated that a nuclear protein from CACO-2 cells and the adult medaka fish intestinal cells binds specifically to the AGACCTTTGC nucleotides in the regulatory element.