The speckling domain of the Wilms tumor suppressor WT1 overlaps with the transcriptional repression domain.
The Wilms tumor suppressor gene WT1 encodes a zinc finger protein, expressed as different splicing variants, that has all the hallmarks of a transcription factor. The -KTS form of WT1 displays a homogeneous localization within the nucleus and has been shown to activate or repress the activity of various target genes. In contrast, the WT1(+KTS) variant demonstrates a speckled pattern of expression within the nucleus. This and its association with factors of the splicing machinery has led to the hypothesis that WT1(+KTS) might play a role in post-transcriptional processes. By the generation of a series of deletion constructs and subsequent immunofluorescence analysis, we have identified and characterized the domain which is responsible for the localization of WT1 variants in nuclear speckles. The speckling domain comprises amino acids 76-120 within the N-terminus of WT1 and is sufficient to target other proteins into distinct nuclear domains. Interestingly the WT1 speckling domain does not overlap with the domain required for interaction with the splicing factor U2AF65 but overlaps with the transcriptional repression domain. Thus our data challenge the view that association of WT1 with spliceosomes is responsible for the speckling phenotype.
Herzer
U
U
Institut für Toxikologie und Genetik, Forschungszentrum Karlsruhe, Hermann von Helmholtz-Platz 1, 76021, Karlsruhe, Germany.
Lutz
B
B
Hartmann
K
K
Englert
C
C
D000818:Animals; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D005807:Genes, Overlapping; D016162:Genes, Wilms Tumor; D006801:Humans; D051379:Mice; D016296:Mutagenesis; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D025721:WT1 Proteins; D016335:Zinc Fingers / Q000235:genetics*
D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D025721:WT1 Proteins