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Oncogenic TLS/ERG and EWS/Fli-1 fusion proteins inhibit RNA splicing mediated by YB-1 protein
H A Chansky1, M Hu, D D Hickstein
1Department of Orthopedics, University of Washington School of Medicine, Seattle, Washington 98195, USA.
Abstract:
The translocation liposarcoma protein TLS has recently been shown to function as an adapter molecule coupling gene transcription to RNA splicing. Here we demonstrate that YB-1, a protein known to play important roles in transcription and translation, interacts with the COOH-terminal domains of TLS and the structurally related Ewing's sarcoma protein EWS. Through this interaction, YB-1 is recruited to RNA polymerase II and promotes splicing of E1A pre-mRNA to the 13S isoform. This splicing function of YB-1 is inhibited by exogenous TLS/ERG or EWS/Fli-1 fusion proteins, which bind to RNA polymerase II but fail to recruit the YB-1 protein. In Ewing's sarcoma cells that express endogenous EWS/Fli-1, this linkage between YB-1 and RNA Pol II via EWS (or TLS) was found to be defective. Together, these results suggest that TLS and EWS fusion proteins may contribute to malignant transformation through disruption of RNA splicing mediated by TLS- and EWS-binding proteins such as YB-1.
Insights
The protein YB-1 interacts with TLS and EWS, promoting RNA splicing. Fusion proteins like EWS/Fli-1 disrupt this process, potentially contributing to Ewing
Area of Science:
- Molecular Biology
- Cancer Research
- Gene Regulation
Background:
- The translocation liposarcoma (TLS) protein acts as an adapter linking gene transcription and RNA splicing.
- YB-1 is a known protein involved in transcription and translation processes.
Purpose of the Study:
- To investigate the interaction between YB-1, TLS, and Ewing's sarcoma protein (EWS).
- To elucidate the role of YB-1 in RNA splicing and its regulation by TLS and EWS.
- To determine the impact of TLS/ERG and EWS/Fli-1 fusion proteins on YB-1-mediated splicing.
Main Methods:
- Investigated protein-protein interactions between YB-1, TLS, and EWS using biochemical assays.
- Assessed the recruitment of YB-1 to RNA polymerase II.
- Analyzed the effect of exogenous and endogenous fusion proteins on pre-mRNA splicing in Ewing's sarcoma cells.
Main Results:
- YB-1 interacts with the COOH-terminal domains of TLS and EWS.
- YB-1 is recruited to RNA polymerase II and promotes the splicing of E1A pre-mRNA to the 13S isoform.
- TLS/ERG and EWS/Fli-1 fusion proteins inhibit YB-1's splicing function by preventing YB-1 recruitment to RNA polymerase II.
- This linkage is defective in Ewing's sarcoma cells expressing endogenous EWS/Fli-1.
Conclusions:
- TLS and EWS proteins interact with YB-1 to regulate RNA splicing.
- TLS and EWS fusion proteins disrupt normal RNA splicing by interfering with YB-1 recruitment.
- This disruption of RNA splicing by fusion proteins may contribute to malignant transformation in Ewing's sarcoma.