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Characterization of Steroid Receptor RNA Activator Protein Function in Modulating the Estrogen Signaling Pathway

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Annual summary rept. 21 Feb 2005-20 Feb 2008

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The bi-faceted products of the Steroid receptor RNA activator gene SRA1 consist of a functional RNA, which acts as a transcriptional co-activator and a protein SRAP, that is conserved in chordates and which function remains elusive. Regarding the functional role of SRAP, we had determined through protein arrays that SRAP is able to interact with various transcription factors. Furthermore, we have established that SRAP is associated to chromatin in MCF-7 cells. We also examined the possible effect of SRAP recruitment on transcription using the potent GAL4-VP16 hybrid transcription activation system. We observed that SRA possesses a transcriptional repressive activity capable of inhibiting the GAL4-VP16 transcription activity. This SRAP transcriptional repressive potential is sensitive to trichostatin A a HDAC inhibitor treatment. In addition, SRAP is able to co-immunoprecipitate HDAC activity. Meanwhile, using splice-switching-oligonucleotides and real-time PCR, we observed that increasing the balance between non-coding SRA to coding-SRA led to an increase in ER-beta expression in T5 breast tumor cells. Further experiments confirm that it is SRAP rather than SRA integrates ER-beta expression. Finally, we found SRAP differentially regulates unbound and agonistantagonist bound estrogen receptor alpha activity in an estrogen responsive elementdependent manner.

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  • Biochemistry
  • Medicine and Medical Research

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