Transforming activity of EWS/FLI is not strictly dependent upon DNA-binding activity.
In approximately 85% of Ewing sarcomas, chromosomal translocations give rise to the chimeric gene EWS/FLI, encoding the N-terminus of the RNA binding protein EWS fused to the DNA-binding domain of the ETS protein FLI-1. EWS/FLI is a stronger transcriptional activator than wild-type FLI-1, although both proteins bind to the same DNA sequences in vitro. In addition, EWS/FLI, but not FLI-1, is a transforming oncogene in NIH3T3 fibroblasts. EWS/FLI is thought to transform through its ability to deregulate the expression of target genes. We introduced several point mutations into the ETS domain of EWS/FLI that abolished DNA-binding activity. Although two of these mutations disrupted the transforming activity of EWS/FLI, one mutated protein containing a substitution of isoleucine 347 with glutamic acid (I347E) retained diminished transforming activity. In addition, EWS/FLI I347E did not activate expression of the endogenous EWS/FLI target gene manic fringe (MFNG). These studies demonstrate that a portion of the oncogenic activity of EWS/FLI is independent of FLI DNA-binding activity.
Jaishankar
S
S
Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, Tennessee, TN 38105, USA.
Zhang
J
J
Roussel
M F
MF
Baker
S J
SJ
D016475:3T3 Cells; D019943:Amino Acid Substitution; D000818:Animals; D001859:Bone Neoplasms / Q000235:genetics*; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism*; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D015514:Oncogene Proteins, Fusion / Q000378:metabolism / Q000502:physiology*; D017354:Point Mutation; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D034802:RNA-Binding Protein EWS; D012512:Sarcoma, Ewing / Q000235:genetics*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D014410:Tumor Stem Cell Assay; D000099232:Proto-Oncogene Protein Spi-1
D004247:DNA; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D034802:RNA-Binding Protein EWS; D015534:Trans-Activators; D014157:Transcription Factors; D000099232:Proto-Oncogene Protein Spi-1; C106031:EWS-FLI fusion protein