The EWS-Oct-4 fusion gene encodes a transforming gene.
The t(6;22)(p21;q12) translocation associated with human bone and soft-tissue tumours results in a chimaeric molecule fusing the NTD (N-terminal domain) of the EWS (Ewing's sarcoma) gene to the CTD (C-terminal domain) of the Oct-4 (octamer-4) embryonic gene. Since the N-terminal domains of EWS and Oct-4 are structurally different, in the present study we have assessed the functional consequences of the EWS-Oct-4 fusion. We find that this chimaeric gene encodes a nuclear protein which binds DNA with the same sequence specificity as the parental Oct-4 protein. Comparison of the transactivation properties of EWS-Oct-4 and Oct-4 indicates that the former has higher transactivation activity for a known target reporter gene containing Oct-4 binding. Deletion analysis of the functional domains of EWS-Oct-4 indicates that the EWS (NTD), the POU domain and the CTD of EWS-Oct-4 are necessary for full transactivation potential. EWS-Oct-4 induced the expression of fgf-4 (fibroblast growth factor 4) and nanog, which are potent mitogens as well as Oct-4 downstream target genes whose promoters contain potential Oct-4-binding sites. Finally, ectopic expression of EWS-Oct-4 in Oct-4-null ZHBTc4 ES (embryonic stem) cells resulted in increased tumorigenic growth potential in nude mice. These results suggest that the oncogenic effect of the t(6;22) translocation is due to the EWS-Oct-4 chimaeric protein and that fusion of the EWS NTD to the Oct-4 DNA-binding domain produces a transforming chimaeric product.
Lee
Jungwoon
J
Laboratory of Molecular and Cellular Biology, Department of Life Science, Sogang University, Seoul 121-742, South Korea.
Kim
Ja Young
JY
Kang
In Young
IY
Kim
Hye Kyoung
HK
Han
Yong-Mahn
YM
Kim
Jungho
J
D000818:Animals; D002471:Cell Transformation, Neoplastic; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics; D004268:DNA-Binding Proteins; D053595:Embryonic Stem Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D050814:Octamer Transcription Factor-3 / Q000235:genetics* / Q000378:metabolism; D015514:Oncogene Proteins, Fusion / Q000235:genetics* / Q000378:metabolism; D009857:Oncogenes / Q000502:physiology*; D034802:RNA-Binding Protein EWS / Q000235:genetics* / Q000378:metabolism; D012512:Sarcoma, Ewing; D014178:Translocation, Genetic
D004268:DNA-Binding Proteins; D050814:Octamer Transcription Factor-3; D015514:Oncogene Proteins, Fusion; D034802:RNA-Binding Protein EWS