Regulation of FAS exon definition and apoptosis by the Ewing sarcoma protein

Cell Rep. 2014 May 22;7(4):1211-26. doi: 10.1016/j.celrep.2014.03.077. Epub 2014 May 10.


The Ewing sarcoma protein EWS is an RNA and DNA binding protein implicated in transcription, pre-mRNA splicing, and DNA damage response. Using CLIP-seq, we identified EWS RNA binding sites in exonic regions near 5' splice sites. A prominent target was exon 6 of the FAS/CD95 receptor, which is alternatively spliced to generate isoforms with opposing activities in programmed cell death. Depletion and overexpression experiments showed that EWS promotes exon 6 inclusion and consequently the synthesis of the proapoptotic FAS/CD95 isoform, whereas an EWS-FLI1 fusion protein characteristic of Ewing sarcomas shows decreased activity. Biochemical analyses revealed that EWS binding promotes the recruitment of U1snRNP and U2AF65 to the splice sites flanking exon 6 and therefore exon definition. Consistent with a role for EWS in the regulation of programmed cell death, cells depleted of EWS show decreased sensitivity to FAS-induced apoptosis, and elevated EWS expression enhances apoptosis in EWS-haploinsufficient Ewing sarcoma cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing
  • Apoptosis / genetics*
  • Cell Line, Tumor
  • Exons*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Oncogene Proteins, Fusion / genetics
  • Oncogene Proteins, Fusion / metabolism
  • Proto-Oncogene Protein c-fli-1 / genetics
  • Proto-Oncogene Protein c-fli-1 / metabolism
  • RNA-Binding Protein EWS / genetics
  • RNA-Binding Protein EWS / metabolism
  • Sarcoma, Ewing / genetics*
  • Sarcoma, Ewing / metabolism
  • Sarcoma, Ewing / pathology*
  • Signal Transduction
  • fas Receptor / genetics*


  • EWS-FLI fusion protein
  • FAS protein, human
  • Oncogene Proteins, Fusion
  • Proto-Oncogene Protein c-fli-1
  • RNA-Binding Protein EWS
  • fas Receptor

Associated data

  • GEO/GSE47431
  • GEO/GSE47790