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Alternative splicing generates multiple SMRT transcripts encoding conserved repressor domains linked to variable
Marianne Malartre1, Stephen Short, Colin Sharpe
1Institute of Biomedical and Biomolecular Science, School of Biological Science, University of Portsmouth, King Henry I St, Portsmouth PO1 2DY, UK.
Nucleic Acids Research
|September 3, 2004
Summary
Silencing mediator for retinoid and thyroid hormone receptor (SMRT) and nuclear receptor corepressor protein (NCoR) are crucial for gene regulation. Unlike NCoR, xSMRT exhibits alternative splicing, generating diverse isoforms with varied nuclear receptor interaction capabilities.
Area of Science:
- Molecular Biology
- Developmental Biology
- Gene Regulation
Background:
- Silencing mediator for retinoid and thyroid hormone receptor (SMRT) and nuclear receptor corepressor protein (NCoR) are key transcriptional corepressors.
- Both proteins feature N-terminal repressor domains interacting with histone deacetylases and C-terminal interaction domains (IDs) with CoRNR box motifs for nuclear receptor (NR) binding.
Purpose of the Study:
- To investigate the differential expression and isoform diversity of xSMRT and NCoR during Xenopus development.
- To understand how alternative splicing of xSMRT impacts its interaction with nuclear receptors.
Main Methods:
- Analysis of Xenopus transcripts for SMRT and NCoR.
- Identification and characterization of alternative splicing events in xSMRT.
- Predictive analysis of how splicing variations affect CoRNR box motifs and NR interaction.
Main Results:
- NCoR produces a single invariant transcript during Xenopus development.
- xSMRT undergoes alternative splicing at four sites in its 3' transcript region, potentially yielding 16 isoforms, but only five are observed in early embryos.
- Alternative splicing sites alter CoRNR box number, flanking sequences, and spacing, predicting differential NR interaction capabilities among xSMRT isoforms.
Conclusions:
- SMRT and NCoR are paralogs with distinct regulatory strategies in Xenopus.
- xSMRT has evolved alternative splicing to generate functional diversity, while NCoR remains invariant, suggesting differential roles in development.