Novel Rbfox2 isoforms associated with alternative exon usage in rat cortex and suprachiasmatic nucleus

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Transcriptome diversity in adult neurons is regulated by RNA binding proteins (RBPs).
• RBFOX3/NeuN, a marker for neuronal maturity, is reduced in suprachiasmatic nucleus (SCN) neurons.
• This reduction may be compensated by altered expression of Rbfox2.

Purpose of the Study:

• To investigate Rbfox2 expression and isoform diversity in the SCN.
• To determine the functional consequences of novel Rbfox2 isoforms in SCN neurons.
• To understand the role of Rbfox2 regional diversity in neuronal specialization.

Main Methods:

• mRNA population analysis in SCN and cerebral cortex.
• Identification and characterization of Rbfox2 isoforms.
• Functional assays of Rbfox2 variant activity on target genes (e.g., Cacna1c, Grin1, Enah).

Main Results:

• No significant superficial change in Rbfox2 expression in the SCN.
• Discovery of multiple novel Rbfox2 isoforms in the SCN.
• A novel C-terminal domain (CTD)-variant Rbfox2 isoform ('-12-40') was 3-fold more abundant in the SCN.
• This variant alters protein sequence and impairs exon 7 exclusion activity in the Cacna1c gene.
• Observed changes in SCN gene transcripts (Cacna1c, Grin1, Enah) consistent with altered RBFOX activity.

Conclusions:

• Rbfox2 exhibits significant regional diversity in the adult brain, particularly in the SCN.
• A novel SCN-specific Rbfox2 isoform contributes to regional transcriptome differences.
• This RBP adaptability supports neuronal specialization and may be relevant in neurological dysfunction.