Pervasive non-triplet alternative splicing drives functional isoform diversity

Area of Science:

• Molecular Biology
• Genetics
• Transcriptomics

Background:

• Alternative mRNA splicing generates transcriptomic diversity.
• Triplet alternative splicing, where reading frames are maintained, is well-studied.
• Non-triplet alternative splicing is often misclassified as noise or error.

Purpose of the Study:

• To investigate the global prevalence, regulation, and function of non-triplet alternative splicing in vivo.
• To categorize the molecular outcomes of non-triplet alternative splicing.
• To assess the conservation of non-triplet alternative splicing in human transcriptomes.

Main Methods:

• RNA-sequencing (RNA-Seq) of wild-type and NMD-deficient C. elegans mutants.
• Bioinformatic analysis to categorize non-triplet splicing events.
• Genetic and molecular analyses to study regulation and function.

Main Results:

• Hundreds of non-triplet alternative splicing events identified across three categories: NMD-sensitive, alternative C-terminal length, and dual-coding isoforms.
• Demonstrated developmental regulation, splicing factor autoregulation, cell-specific splicing, and isoform-specific functions.
• Identified similar patterns in human transcriptomes, indicating broad biological relevance.

Conclusions:

• Non-triplet alternative splicing is a significant and underappreciated mechanism for regulating gene expression.
• This splicing type contributes substantially to protein-coding diversity.
• The findings highlight the functional importance and prevalence of non-triplet alternative splicing across species.