The transcriptional regulation of the human cholesteryl ester transfer protein (CETP) gene by retinoic acid was investigated by a transient transfection assay. A series of deleted vectors generated from the 5'-upstream region (3434 bp) of the CETP gene linked to the luciferase reporter gene was individually transfected to HepG2 cells. Promoter analyses revealed essential regulatory machinery in the -110/-40 region of the upstream sequence of the human CETP gene. When the cells transfected with the reporter vectors were stimulated with all-trans retinoic acid (tRA), the hormone response was drastically reduced when the -165/-110 region was deleted, thereby suggesting that there may be a retinoic acid receptor element (RARE) in the region. A footprinting analysis showed that the DNA segment at the -165/-134 is protected by the HepG2 nuclear extract. A competition analysis on the gel mobility shift assay using consensus RARE and a purified retinoic acid receptor confirmed the -165/-134 region as being RARE.
Copyright 1999 Academic Press.