Identification of a novel suppressive vitamin D response sequence in the 5'-flanking region of the murine Id1 gene.
Vitamin D promotes differentiation of cells either by simply enhancing phenotypic gene expression and/or by suppressing expression of inhibitors of differentiation. Previously, we reported that expression of a gene encoding Id1, a negative type helix-loop-helix transcription factor, was transcriptionally suppressed by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) (1). To identify the sequence required for the negative regulation by 1, 25(OH)2D3, a 1.5-kilobase 5'-flanking region of murine Id1 gene was examined by transiently transfecting luciferase reporter constructs into ROS17/2.8 osteoblastic cells. The transcriptional activity of this construct was repressed by 10(-8) M 1,25(OH)2D3. Deletion analysis revealed that a 57-base pair (bp) upstream response sequence (URS) (-1146/-1090) was required for the suppression by 1,25(OH)2D3. This sequence conferred negative responsiveness to 1,25(OH)2D3 to a heterologous SV40 promoter. The 57-bp URS contained not only Egr-1 consensus sequence (2) but also four direct repeats of a heptamer sequence (C/A)CAGCCC. Electrophoresis mobility shift assay revealed that the 57-bp URS formed specific nuclear protein-DNA complexes, which were neither competed by previously known positive and negative vitamin D response elements nor supershifted by anti-vitamin D receptor antibody, suggesting the absence of vitamin D receptor in these complexes. These results indicate the involvement of the novel 57-bp sequence in the vitamin D suppression of Id1 gene transcription.
Ezura
Y
Y
Department of Molecular Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 101, Japan.
Tournay
O
O
Nifuji
A
A
Noda
M
M
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D018257:Helix-Loop-Helix Motifs; D051798:Inhibitor of Differentiation Protein 1; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects; D051381:Rats; D012097:Repressor Proteins; D017384:Sequence Deletion; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects*; D014807:Vitamin D / Q000494:pharmacology*
C497454:ID1 protein, rat; D051798:Inhibitor of Differentiation Protein 1; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014807:Vitamin D