Phase separation of the oncogenic fusion protein EWS::FLI1 is modulated by its DNA-binding domain

• 成果类型: Article
• 署名作者: Selig, Emily E.; Sohn, Erich J.; Stoja, Aiola; Moreno-Romero, Alma K.; Akula, Shivani; Xu, Xiaoping; Bishop, Alexander J. R.; Libich, David S.
• 署名单位: University of Texas System; University of Texas at San Antonio; University of Texas System; University of Texas at San Antonio; University of Texas System; University of Texas at San Antonio
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8974
• DOI: 10.1073/pnas.2221823122
• 发表日期: 2025-05-16
• 关键词: rna-polymerase-ii; c-terminal domain; transcription factor; ets-domain; transforming activity; gene; ews; interacts; ews-fli1; ews/fli

摘要

Ewing sarcoma (EwS) is an aggressive cancer of bone and soft tissue that predominantly affects children and young adults. A chromosomal translocation joins the low-complexity domain (LCD) of the RNA-binding protein EWS (EWSLCD) with the DNA-binding domain of Friend leukemia integration 1 (FLI1(DBD)), creating EWS::FLI1, a potent fusion oncoprotein essential for EwS development and responsible for over 85% of EwS tumors. EWS::FLI1 forms biomolecular condensates in vivo and promotes tumorigenesis through mediation of aberrant transcriptional changes and by interfering with the normal functions of nucleic acid-binding proteins like EWS through a dominant-negative mechanism. In particular, the expression of EWS::FLI1 in EwS directly interferes with the biological functions of EWS leading to alternate splicing events and defects in DNA-damage repair pathways. Though the EWSLCD is capable of phase separation, here we report a direct interaction between FLI1(DBD) and EWSLCD that enhances condensate formation and alters the physical properties of the condensate. This effect was conserved for three related E-twenty-six transformation-specific (ETS) DNA-binding domains (DBDs) while DNA binding blocked the interaction with EWSLCD and inhibited EWS::FLI1 condensate formation. NMR spectroscopy and mutagenesis studies confirmed that ETS DBDs transiently interact with EWSLCD via the ETS DBDs wings. Together these results revealed that ETS DBDs, particularly FLI1(DBD), enhance EWSLCD condensate formation and rigidity, supporting a model in which electrostatic and structural interactions drive condensate dynamics with implications for EWS::FLI1-mediated transcriptional regulation in EwS.