Regulation of multiple insulin-like growth factor binding protein genes by 1alpha,25-dihydroxyvitamin D3.
Recently, insulin-like growth factor binding proteins (IGFBPs) have been found to be primary mediators of the anti-proliferative actions of the nuclear hormone 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], but dependent on cellular context IGFBPs can also have a mitogenic effect. In this study, we performed expression profiling of all six human IGFBP genes in prostate and bone cancer cells and demonstrated that IGFBP1, 3 and 5 are primary 1alpha,25(OH)2D3 target genes. In silico screening of the 174 kb of genomic sequence surrounding all six IGFBP genes identified 15 candidate vitamin D response elements (VDREs) close to or in IGFBP1, 2, 3 and 5 but not in the IGFBP4 and 6 genes. The putative VDREs were evaluated in vitro by gelshift assays and in living cells by reporter gene and chromatin immuno-precipitation (ChIP) assays. Of these 10 VDREs appear to be functional. ChIP assays demonstrated for each of these an individual, stimulation time-dependent association profile not only with the vitamin D receptor, but also with first heterodimeric partner the retinoid X receptor, other regulatory complex components and phosphorylated RNA polymerase II. Some of the VDREs are located distantly from the transcription start sites of IGFBP1, 3 and 5, but all 10 VDREs seem to contribute to the regulation of the genes by 1alpha,25(OH)2D3. In conclusion, IGFBP1, 3 and 5 are primary 1alpha,25(OH)2D3 target genes that in intact cells are each under the control of multiple VDREs.
Matilainen
Merja
M
Department of Biochemistry, University of Kuopio, P.O. box 1627, IN-70211 Kuopio, Finland.
Malinen
Marjo
M
Saavalainen
Katri
K
Carlberg
Carsten
C
D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002843:Chromatin / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000096:biosynthesis / Q000235:genetics; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000096:biosynthesis / Q000235:genetics; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000096:biosynthesis / Q000235:genetics; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000096:biosynthesis / Q000235:genetics; D018969:Insulin-Like Growth Factor Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism; D030181:Vitamin D Response Element
D002843:Chromatin; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D018975:Insulin-Like Growth Factor Binding Protein 5; D018969:Insulin-Like Growth Factor Binding Proteins; D002117:Calcitriol