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Oncoprotein TLS interacts with serine-arginine proteins involved in RNA splicing
1Medical Research Service, Veterans Affairs Puget Sound Health Care System, Seattle, Washington 98108, USA.
Abstract:
The gene encoding the human TLS protein, also termed FUS, is located at the site of chromosomal translocations in human leukemias and sarcomas where it forms a chimeric fusion gene with one of several different genes. To identify interacting partners of TLS, we screened a yeast two-hybrid cDNA library constructed from mouse hematopoietic cells using the C-terminal region of TLS in the bait plasmid. Two cDNAs encoding members of the serine-arginine (SR) family of proteins were isolated. The first SR protein is the mouse homolog of human splicing factor SC35, and the second SR member is a novel 183-amino acid protein that we term TASR (TLS-associated serine-arginine protein). cDNA cloning of human TASR indicated that mouse and human TASR have identical amino acid sequences. The interactions between TLS and these two SR proteins were confirmed by co-transfection and immunoprecipitation studies. In vivo splicing assays indicated that SC35 and TASR influence splice site selection of adenovirus E1A pre-mRNA. TLS may recruit SR splicing factors to specific target genes through interaction with its C-terminal region, and chromosomal translocations that truncate the C-terminal region of TLS may prevent this interaction. Thus TLS translocations may alter RNA processing and play a role in malignant transformation.
Insights
Researchers identified novel proteins interacting with the TLS (translocated lysosomal spectrin-like) protein, a key player in certain cancers. These interactions with splicing factors may explain how TLS gene fusions contribute to malignant transformation.
Area of Science:
- Molecular Biology
- Cancer Genetics
- RNA Splicing
Background:
- The TLS (FUS) gene is frequently involved in chromosomal translocations in human leukemias and sarcomas, forming fusion genes.
- These translocations often involve the C-terminal region of TLS, suggesting its functional importance.
Purpose of the Study:
- To identify proteins that interact with the TLS protein.
- To investigate the role of TLS-interacting proteins in RNA processing and malignant transformation.
Main Methods:
- Yeast two-hybrid screening of a mouse hematopoietic cDNA library using the C-terminal region of TLS.
- Co-transfection and immunoprecipitation assays to confirm protein interactions.
- In vivo splicing assays using adenovirus E1A pre-mRNA.
Main Results:
- Two serine-arginine (SR) proteins, splicing factor SC35 and a novel protein TASR (TLS-associated serine-arginine protein), were identified as TLS interactors.
- Mouse and human TASR proteins share identical amino acid sequences.
- SC35 and TASR were shown to influence splice site selection.
- TLS interacts with SR proteins via its C-terminal region.
Conclusions:
- TLS may recruit SR splicing factors to target genes through its C-terminal region.
- Truncation of the TLS C-terminus due to chromosomal translocations may disrupt this interaction.
- Altered RNA processing resulting from disrupted TLS-SR protein interaction could contribute to malignant transformation.