O-GlcNAcylation is involved in the transcriptional activity of EWS-FLI1 in Ewing's sarcoma.
The oncogene EWS-FLI1 encodes a chimeric transcription factor expressed in Ewing's sarcoma family tumors (ESFTs). EWS-FLI1 target gene expression is thought to drive ESFT pathogenesis and, therefore, inhibition of EWS-FLI1 activity holds high therapeutic promise. As the activity of many transcription factors is regulated by post-translational modifications, we studied the presence of modifications on EWS-FLI1. The immuno-purified fusion-protein was recognized by an antibody specific for O-linked beta-N-acetylglucosaminylation, and bound readily to a phosphoprotein-specific dye. Inhibition of Ser/Thr-specific phophatases increased EWS-FLI1 molecular weight and reduced its O-GlcNAc content, suggesting that phosphorylation and O-GlcNAcylation of EWS-FLI1 interact dynamically. By mutation analysis, O-GlcNAcylation was delineated to Ser/Thr residues of the amino-terminal EWS transcriptional-activation domain. Metabolic inhibition of the hexosamine biosynthetic pathway abrogated O-GlcNAcylation of EWS-FLI1 and interfered specifically with transcriptional activation of the EWS-FLI1 target Id2. These results suggest that drugs modulating glycosylation of EWS-FLI1 interfere functionally with its activity and might, therefore, constitute promising additions to the current ESFT chemotherapy.
Bachmaier
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Children's Cancer Research Institute, St Anna Kinderkrebsforschung, Vienna, Austria.
Aryee
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DN
Jug
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Kauer
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Kreppel
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Lee
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KA
Kovar
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H
D000215:Acylation; D006801:Humans; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics*; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000235:genetics*; D014158:Transcription, Genetic
C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS