A retinoic acid response element from the rat CRBPI promoter is activated by an RAR/RXR heterodimer.
The expression of the rat cellular retinol binding protein I (rCRBPI) can be upregulated in vivo by retinoic acid (RA). Here we have analyzed the rCRBPI promoter region and compared it to the corresponding mouse sequence. We find that the CRBPI 5' flanking region has been highly conserved between rat and mouse, including a RA response element (RARE) approximately 1 kb upstream of the start of transcription. The RARE is of the direct repeat type with a two nucleotide spacer. Like other direct repeat RAREs, this response element is activated by RAR alpha and beta but not by RAR gamma 1. Furthermore, the rCRBPI-RARE is most effectively activated when both RAR and RXR are present. In addition RAR/RXR heterodimers are required for efficient binding to the rCRBPI-RARE, while RARs or RXR alone do not interact effectively with this response element. The rCRBPI gene is therefore most likely activated in vitro by a RAR/RXR heterodimer.
Husmann
M
M
Cancer Center, La Jolla Cancer Research Foundation, CA 92037.
Hoffmann
B
B
Stump
D G
DG
Chytil
F
F
Pfahl
M
M
D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000502:physiology*; D003001:Cloning, Molecular; D004357:Drug Synergism; D005786:Gene Expression Regulation; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D051381:Rats; D011956:Receptors, Cell Surface / Q000502:physiology*; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D012177:Retinol-Binding Proteins / Q000235:genetics*; D054840:Retinol-Binding Proteins, Cellular; D016415:Sequence Alignment; D014157:Transcription Factors; D014212:Tretinoin / Q000378:metabolism
D002352:Carrier Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D011956:Receptors, Cell Surface; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D012177:Retinol-Binding Proteins; D054840:Retinol-Binding Proteins, Cellular; D014157:Transcription Factors; D014212:Tretinoin