Characterization of the rat RALDH1 promoter. A functional CCAAT and octamer motif are critical for basal promoter activity.
Retinal dehydrogenase type 1 (RALDH1) catalyzes the oxidation of retinal to retinoic acid (RA), a metabolite of vitamin A important for embryogenesis and tissue differentiation. Rat RALDH1 is expressed to high levels in developing kidney, and in stomach, intestine epithelia. To understand the mechanisms of the transcriptional regulation of rat RALDH1, we cloned a 1360-base pair (bp) 5'-flanking region of RALDH1 gene. Using luciferase reporter constructs transfected into HEK 293 and LLCPK (kidney-derived) cells, basal promoter activity was associated with sequences between -80 and +43. In this minimal promoter region, TATA and CCAAT cis-acting elements as well as SP1, AP1 and octamer (Oct)-binding sites were present. The CCAAT box and Oct-binding site, located between positions -72 and -68 and -56 and -49, respectively, were shown by deletion analysis and site-directed mutation to be critical for promoter activity. Nuclear extracts from kidney cells contain proteins specifically binding the Oct and CCAAT sequences, resulting in the formation of six complexes, while different patterns of complexes were observed with non-kidney cell extracts. Gel shift assays using either single or double mutations of the Oct and CCAAT sequences as well as super shift assays demonstrated single and double occupancy of these two sites by Oct-1 and CBF-A. In addition, unidentified proteins also bound the Oct motif specifically in the absence of CBF-A binding. These results demonstrate specific involvement of Oct and CCAAT-binding proteins in the regulation of RALDH1 gene.
Guimond
Julie
J
Laboratory of Nutrition and Cancer, Centre Hospitalier de l'Universite de Montreal-Hotel-Dieu, Montreal, Quebec, Canada
Devost
Dominic
D
Brodeur
Helene
H
Mader
Sylvie
S
Bhat
Pangala V
PV
D024506:5' Flanking Region / Q000235:genetics*; D000445:Aldehyde Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D023081:CCAAT-Binding Factor / Q000032:analysis / Q000737:chemistry; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000032:analysis; D024202:Electrophoretic Mobility Shift Assay; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008969:Molecular Sequence Data; D050813:Octamer Transcription Factor-2; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology*; D051381:Rats; D050697:Retinal Dehydrogenase; D013552:Swine; D014157:Transcription Factors / Q000032:analysis / Q000737:chemistry; D024363:Transcription Initiation Site
D023081:CCAAT-Binding Factor; D004268:DNA-Binding Proteins; C492063:NFYB protein, human; C492064:Nfyb protein, rat; C059328:Oct-2B protein, mouse; D050813:Octamer Transcription Factor-2; D014157:Transcription Factors; D000445:Aldehyde Oxidoreductases; D050697:Retinal Dehydrogenase