WT1-mediated transcriptional activation is inhibited by dominant negative mutant proteins.
The WT1 tumor suppressor gene encodes four isoforms of a zinc finger transcription factor with both activation and repression functions which are dependent upon promoter architecture. Using a simple HSV-tk promoter containing 5'-Egr-1/WT1-binding sites, we found that WT1 isoforms (A) and (B) strongly activated transcription. WT1(A) and (B) bound equally well to the Egr-1/WT1-binding site, but WT1(B), which contains a 17 amino acid insertion compared to WT1(A), was a consistently stronger activator of transcription than WT1(A). Transcriptional activation by wild-type WT1 was inhibited by coexpression of WT(PM) or WT(AR), genetically defined dominant negative alleles of WT1. In vitro, as well as in the yeast two-hybrid system, WT1 protein associated with itself and with dominant negative mutant proteins. The major domain required for self-association and inhibition of transcriptional activation mapped to the first 182 amino acids of WT1. Dominant negative WT1 alleles may play a role in tumorigenesis by associating with wild-type WT1 proteins and decreasing their transcriptional activity.
Reddy
J C
JC
Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029, USA.
Morris
J C
JC
Wang
J
J
English
M A
MA
Haber
D A
DA
Shi
Y
Y
Licht
J D
JD
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005799:Genes, Dominant; D016147:Genes, Tumor Suppressor; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D013577:Syndrome; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D025721:WT1 Proteins; D009396:Wilms Tumor / Q000235:genetics*
D017931:DNA Primers; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D025721:WT1 Proteins