Human platelet-derived growth factor A chain is transcriptionally repressed by the Wilms tumor suppressor WT1.
Wilms tumor, an embryonic kidney malignancy, accounts for approximately 6% of all pediatric neoplasms. A gene implicated in the genesis of this tumor, the Wilms tumor suppressor gene (WT1), encodes a zinc-finger DNA-binding protein (WT1) that functions as a transcriptional repressor. In certain Wilms tumors, the platelet-derived growth factor A chain (PDGF-A) is overexpressed; it has therefore been suggested that it may play an autocrine role in development of these neoplasms. Since the PDGF-A promoter contains putative binding sites for WT1, we explored the role of WT1 in regulating A-chain expression. The major PDGF-A promoter activity was localized in transient transfection assays to a region spanning from -643 to + 8 relative to the transcription start site. WT1 bound to several sites in this region of the promoter, as demonstrated by gel-shift analysis and DNase I footprinting, and functioned as a powerful repressor of PDGF-A transcription in vivo. Maximal repression (> 50-fold) of the PDGF-A promoter was dependent on the presence of multiple WT1 binding sites in transient transfection assays. Our observations suggest a mechanism for normal downregulation of a growth factor gene and of an autocrine growth process of import in kidney development and other biological systems.
Gashler
A L
AL
Department of Biochemistry and Molecular Biology, University of Chicago, IL 60637-1963.
Bonthron
D T
DT
Madden
S L
SL
Rauscher
F J
FJ
Collins
T
T
Sukhatme
V P
VP
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D016147:Genes, Tumor Suppressor; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics*; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016366:Open Reading Frames; D010982:Platelet-Derived Growth Factor / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D013489:Suppression, Genetic; D014158:Transcription, Genetic; D014162:Transfection; D025721:WT1 Proteins; D009396:Wilms Tumor / Q000235:genetics*; D016335:Zinc Fingers / Q000235:genetics*
D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D010982:Platelet-Derived Growth Factor; D012097:Repressor Proteins; D025721:WT1 Proteins