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Modulation of EWS/WT1 activity by the v-Src protein tyrosine kinase
1Department of Biochemistry, McGill University, McIntyre Medical Sciences, Montreal, Que., Canada.
Abstract:
Desmoplastic small round cell tumor (DSRCT) is a malignant human cancer that is associated with a specific t(11;22) chromosome translocation, where 265 amino acids from the EWS amino-terminus are fused to the DNA binding domain of the WT1 tumor suppressor gene. We have noticed the presence of several SH3 interacting domains within the amino-terminus of EWS and have assessed the potential of EWS/WT1 to interact with such motifs. We find that EWS/WT1 can associate with the SH3 domain of several proteins, including v-Src. Ectopic expression of v-Src phosphorylates EWS/WT1 in vivo, as well as enhances the transactivation ability of the EWS amino-terminal domain. Structural alteration of the v-Src SH2 or SH3 domains produced mutants that could not interact with EWS/WT1 nor augment the transcriptional properties of EWS. Taken together, our results suggest the possibility that some transcriptional properties of EWS/WT1 may be regulated by a cytoplasmic signaling pathway.
Insights
Desmoplastic small round cell tumor (DSRCT) involves the EWS/WT1 fusion protein. This study shows v-Src signaling can regulate EWS/WT1
Area of Science:
- Molecular oncology
- Cancer genetics
Background:
- Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive cancer characterized by a specific chromosomal translocation, t(11;22).
- This translocation results in the EWS/WT1 fusion gene, encoding a chimeric protein critical for DSRCT development.
Purpose of the Study:
- To investigate the interaction between the EWS/WT1 fusion protein and SH3-binding motifs.
- To determine if cytoplasmic signaling pathways, specifically involving v-Src, can modulate the function of EWS/WT1.
Main Methods:
- Assessed the association of EWS/WT1 with SH3 domains of various proteins, including v-Src.
- Utilized ectopic expression of v-Src to study its effect on EWS/WT1 phosphorylation and transactivation.
- Employed structural alterations of v-Src SH2 and SH3 domains to confirm interaction specificity.
Main Results:
- EWS/WT1 was found to associate with the SH3 domain of proteins like v-Src.
- Ectopic v-Src expression led to in vivo phosphorylation of EWS/WT1 and enhanced its transactivation capabilities.
- Mutations in v-Src's SH2 or SH3 domains abolished interaction with EWS/WT1 and its transcriptional augmentation.
Conclusions:
- The findings suggest that EWS/WT1's transcriptional activity may be regulated by cytoplasmic signaling pathways.
- Specifically, the v-Src signaling pathway appears to play a role in modulating EWS/WT1 function in DSRCT.