Fusion protein EWS-FLI1 is incorporated into a protein granule in cells

Nasiha S. Ahmed, Lucas M. Harrell, Daniel R. Wieland, Michelle A. Lay, Valery F. Thompson, Jacob C. Schwartz

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Ewing sarcoma is driven by fusion proteins containing a low-complexity (LC) domain that is intrinsically disordered and a powerful transcriptional regulator. The most common fusion protein found in Ewing sarcoma, EWS-FLI1, takes its LC domain from the RNA-binding protein EWSR1 (Ewing sarcoma RNA-binding protein 1) and a DNA-binding domain from the transcription factor FLI1 (Friend leukemia virus integration 1). EWS-FLI1 can bind RNA polymerase II (RNA Pol II) and self-assemble through its LC domain. The ability of RNA-binding proteins like EWSR1 to self-assemble or phase separate in cells has raised questions about the contribution of this process to EWS-FLI1 activity. We examined EWSR1 and EWS-FLI1 activity in Ewing sarcoma cells by siRNA-mediated knockdown and RNA-seq analysis. More transcripts were affected by the EWSR1 knockdown than expected and these included many EWS-FLI1 regulated genes. We reevaluated physical interactions between EWS-FLI1, EWSR1, and RNA Pol II, and used a cross-linking-based strategy to investigate protein assemblies associated with the proteins. The LC domain of EWS-FLI1 was required for the assemblies observed to form in cells. These results offer new insights into a protein assembly that may enable EWS-FLI1 to bind its wide network of protein partners and contribute to regulation of gene expression in Ewing sarcoma.

Original languageEnglish (US)
Pages (from-to)920-932
Number of pages13
Issue number8
StatePublished - Aug 2021


  • Ewing sarcoma
  • Fusion proteins
  • Granules
  • Phase separation
  • Transcription

ASJC Scopus subject areas

  • Molecular Biology


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