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Identification of new human coding steroid receptor RNA activator isoforms
Ethan Emberley1, Guo-Jian Huang, Mohammad K Hamedani
1Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3EOW3.
Biochemical and Biophysical Research Communications
|February 5, 2003
Summary
Steroid receptor co-activator (SRA) functional RNAs can encode proteins. New long SRA isoforms produce nuclear proteins in breast cancer cells, indicating widespread expression of coding SRA in these cell lines.
Area of Science:
- Molecular Biology
- RNA Biology
- Cancer Research
Background:
- Steroid receptor co-activator (SRA) is a functional RNA.
- SRA is classified within the functional non-coding RNA family.
- Previously, SRA transcripts did not yield detectable proteins in vitro or in vivo.
Purpose of the Study:
- To identify and characterize novel SRA-RNA isoforms.
- To investigate the protein-coding potential of these new isoforms.
- To determine the expression of coding SRA isoforms and proteins in breast cancer cell lines.
Main Methods:
- Identification of new SRA-RNA isoforms with extended 5' extremities.
- In vitro and in vivo translation experiments.
- Transfection of MCF-7 human breast cancer cells.
- Reverse-transcription polymerase chain reaction (RT-PCR) and Western blot analysis.
Main Results:
- Three new long SRA-RNA isoforms were identified.
- These isoforms could encode a stable protein in vitro.
- Transfection resulted in the in vivo production of a nuclear protein.
- Endogenous coding SRA isoforms and their proteins were confirmed in breast cancer cell lines.
Conclusions:
- Full-length SRA-RNAs capable of encoding stable proteins are expressed.
- These coding SRA isoforms are widely present in breast cancer cell lines.
- This finding challenges the prior classification of SRA as solely non-coding.