Corepressor diversification by alternative mRNA splicing is species specific

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Genetics

Background:

• SMRT (silencing mediator of retinoic acid receptor) and NCoR (nuclear receptor corepressor 1) are key transcriptional corepressors.
• These corepressors mediate gene silencing by various transcription factors, including nuclear hormone receptors.
• Alternative mRNA splicing in mice generates diverse SMRT and NCoR protein variants with distinct tissue-specific functions.

Purpose of the Study:

• To investigate the evolutionary history of alternative splicing in SMRT and NCoR.
• To understand how alternative splicing contributes to the functional diversification of these corepressors across species.

Main Methods:

• Comparative analysis of SMRT and NCoR alternative splicing patterns across different vertebrate species.
• Identification of conserved and novel alternative splicing sites.

Main Results:

• SMRT alternative splicing is a relatively recent evolutionary event, with limited utilization in fish, birds, reptiles, and marsupials, but extensive use in placental mammals.
• NCoR alternative splicing, observed in mice and linked to metabolic regulation, appears to have evolved independently and later than SMRT, demonstrating convergent evolution.
• The extent of alternative splicing for both SMRT and NCoR varies significantly across the studied taxa.

Conclusions:

• Alternative splicing has played a crucial role in diversifying the functions of SMRT and NCoR throughout evolution.
• This diversification allows for specialized roles of these corepressors in different tissues and species.
• The independent evolution of NCoR alternative splicing highlights convergent evolutionary strategies for functional adaptation.