Functional characterization of WT1 binding sites within the human vitamin D receptor gene promoter.
The Wilms' tumor suppressor gene, wt1, encodes a zinc finger transcription factor that can regulate gene expression. It plays an essential role in tumorigenesis, kidney differentiation, and urogenital development. To identify WT1 downstream targets, gene expression profiling was conducted using a cDNA array hybridization approach. We confirm herein that the human vitamin D receptor (VDR), a ligand-activated transcription factor, is a WT1 downstream target. Nuclear run on experiments demonstrated that the effect of WT1 on VDR expression is at the transcriptional level. Transient transfection assays, deletion mutagenesis, electrophoretic mobility shift assays, and chromatin immunoprecipitation assays suggest that, although WT1 is presented with a possibility of three binding sites within the VDR promoter, activation of the human VDR gene appears to occur through a single site. This site differs from a previously identified WT1-responsive site in the murine VDR promoter (Maurer U, Jehan F, Englert C, Hübinger G, Weidmann E, DeLucas HF, and Bergmann L. J Biol Chem 276: 3727-3732, 2001). We also show that the products of a Denys-Drash syndrome allele of wt1 inhibit WT1-mediated transactivation of the human VDR promoter. Our results indicate that the human VDR gene is a downstream target of WT1 and may be regulated differently than its murine counterpart.
Lee
T H
TH
Department of Biochemistry, McGill Cancer Center, McGill University, Montreal, Quebec, Canada H3G 1Y6.
Pelletier
J
J
D000483:Alleles; D001665:Binding Sites / Q000502:physiology; D001667:Binding, Competitive / Q000235:genetics; D002460:Cell Line; D030321:Denys-Drash Syndrome / Q000235:genetics; D020862:GC Rich Sequence / Q000502:physiology; D020869:Gene Expression Profiling; D006801:Humans; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic / Q000502:physiology*; D018167:Receptors, Calcitriol / Q000235:genetics*; D013329:Structure-Activity Relationship; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection; D025721:WT1 Proteins / Q000378:metabolism*; D009396:Wilms Tumor / Q000235:genetics
D018167:Receptors, Calcitriol; D025721:WT1 Proteins