Background: The human aldehyde dehydrogenase-2 promoter contains sites that bind members of the nuclear receptor family, and one (designated FP330-3') is predicted to bind retinoic acid receptors.
Methods: Binding of retinoid receptors to the FP330-3' oligonucleotide duplex and point mutations thereof was assayed using electrophoretic mobility shift assays. The function of the promoter element was determined in transfection assays.
Results: Heterodimers of retinoic acid receptor (RAR)alpha, beta, and gamma with retinoid X receptor (RXR)alpha bound the FP330-3' site. Mutagenesis of the FP330-3' site suggested that either the upstream DR-5 or downstream DR-1 could mediate binding of RAR/RXR. FP330-3' oligonucleotide duplexes were not bound by in vitro translated RXR homodimers but weakly competed with a synthetic DR-1 oligonucleotide duplex for binding by RXR. A reporter construct carrying four copies of the FP330-3' element was induced by cotransfection of rat hepatoma cells with a construct encoding RARalpha, when the RAR-specific ligand AM580 was present. Each of the three RXR isoforms alpha, beta, and gamma stimulated the expression of reporter constructs containing the FP330-3' sites in a 9-cis retinoic acid-dependent fashion in cells in culture. This was confirmed in the case of RXRalpha using the RXR-specific ligand methoprene.
Conclusion: The human aldehyde dehydrogenase-2 promoter contains a retinoid response element, which may contribute to regulation of the gene.