Ewing sarcoma fusion protein EWSR1/FLI1 interacts with EWSR1 leading to mitotic defects in zebrafish embryos and human cell lines.
The mechanism whereby the fusion of EWSR1 with the ETS transcription factor FLI1 contributes to malignant transformation in Ewing sarcoma remains unclear. We show that injection of human or zebrafish EWSR1/FLI1 mRNA into developing zebrafish embryos leads to mitotic defects with multipolar and disorganized mitotic spindles. Expression of human EWSR1/FLI1 in HeLa cells also results in mitotic defects, along with mislocalization of Aurora kinase B, a key regulator of mitotic progression. Because these mitotic abnormalities mimic those observed with the knockdown of EWSR1 in zebrafish embryos and HeLa cells, we investigated whether EWSR1/FLI1 interacts with EWSR1 and interferes with its function. EWSR1 coimmunoprecipitates with EWSR1/FLI1, and overexpression of EWSR1 rescues the mitotic defects in EWSR1/FLI1-transfected HeLa cells. This interaction between EWSR1/FLI1 and EWSR1 in Ewing sarcoma may induce mitotic defects leading to genomic instability and subsequent malignant transformation.
Experimental Transplantation and Immunology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
Lisa J
LJ
Embree
Mizuki
M
Azuma
Dennis D
DD
Hickstein
D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000473:pathology; D042822:Genomic Instability; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000235:genetics; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000473:pathology* / Q000662:veterinary; D014162:Transfection; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
D002148:Calmodulin-Binding Proteins; C500986:EWSR1 protein, human; C529969:Ewsr1a protein, zebrafish; C078433:FLI1 protein, human; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins; D029961:Zebrafish Proteins