Splicing of many human genes involves sites embedded within introns

Area of Science:

• Molecular Biology
• Genomics
• Transcriptomics

Background:

• The canonical model of intron splicing involves the removal of introns as single, continuous segments.
• This model has been the foundation for understanding gene expression and RNA processing.

Purpose of the Study:

• To investigate the accuracy of the conventional splicing model in human genes.
• To characterize novel splicing intermediates and their functional significance.
• To explore the regulatory implications of alternative splicing pathways.

Main Methods:

• Transcription of the SAMD4A gene with a large first intron was initiated.
• Genome-wide analysis was performed to identify genes exhibiting intermediate intron splicing.
• Targeted genome editing was employed to study the effects of inhibiting splicing intermediates.

Main Results:

• Splicing was observed to join exon 1 to successive points within intron 1 before the canonical acceptor site.
• >60% of active human genes produce products via intermediate intron splicing.
• These splicing intermediates are present at approximately 15% of primary transcript levels and possess unique molecular features.

Conclusions:

• The conventional model of intron splicing is insufficient to describe splicing in many human genes.
• Intermediate intron splicing represents a widespread and significant mechanism in human transcriptome regulation.
• These findings reveal novel layers of complexity in gene expression and RNA processing.