Xenopus embryos lacking specific isoforms of the corepressor SMRT develop abnormal heads.

Area of Science:

• Molecular Biology
• Developmental Biology
• Genetics

Background:

• The corepressor SMRT interacts with nuclear receptors, regulating gene expression.
• SMRT contains CoRNR box motifs in its carboxy-terminal region for these interactions.
• SMRT exhibits isoforms with varying numbers of CoRNR boxes due to alternative splicing.

Purpose of the Study:

• To investigate the role of SMRT alternative splicing in Xenopus development.
• To determine the functional consequences of specific SMRT isoforms on gene regulation and development.

Main Methods:

• Utilized antisense morpholino oligonucleotides in Xenopus embryos to target alternative splicing of SMRT exon 37b.
• Inhibited the formation of SMRT isoforms containing exon 37b, resulting in two-CoRNR-box isoforms.
• Analyzed gene expression of thyroid hormone and retinoid signaling pathways.
• Observed developmental phenotypes including swimming and morphological changes.

Main Results:

• Elimination of exon 37b selectively affected thyroid hormone signaling targets, not retinoid signaling.
• Xenopus embryos lacking exon 37b displayed swimming abnormalities, altered head morphology, and disorganized peripheral axons.
• SMRT isoforms with two CoRNR boxes, due to exon 37b exclusion, are critical for normal development.

Conclusions:

• Alternative splicing of SMRT, specifically exon 37b inclusion, plays a critical role in Xenopus development.
• Differential regulation of SMRT isoforms impacts distinct signaling pathways.
• SMRT alternative splicing is essential for normal neurodevelopment and organogenesis.