Transcriptome-wide splicing network reveals specialized regulatory functions of the core spliceosome

Area of Science:

• Molecular Biology
• Genomics
• Cell Biology

Background:

• The spliceosome is essential for removing introns from pre-mRNA (pre-mRNA splicing), a process vital for gene expression.
• Dysregulation of splicing is implicated in various human pathologies, including cancer.
• Understanding spliceosome function is critical for deciphering cellular mechanisms and disease states.

Purpose of the Study:

• To conduct a comprehensive, transcriptome-wide analysis of spliceosome components and regulators.
• To reconstruct functional splicing factor networks governing alternative splicing decisions.
• To elucidate the roles of specific spliceosome subcomplexes in regulating splicing fidelity and alternative splicing.

Main Methods:

• Systematic knockdown of 305 spliceosome components and regulators in human cancer cells.
• Transcriptome-wide analyses (RNA sequencing) to assess splicing changes.
• Bioinformatic reconstruction of functional splicing factor networks.

Main Results:

• Detailed functional splicing factor networks were reconstructed, highlighting cross-regulatory circuits.
• The architecture of U4/U6.U5 tri-small nuclear ribonucleoprotein (snRNP) complexes was shown to regulate splice site pairing.
• A novel division of labor among U1 snRNP protein components in regulating exon definition and alternative 5' splice site selection was discovered.

Conclusions:

• This study provides a valuable resource for exploring the complex mechanisms of splicing regulation in both physiological and pathological contexts.
• The findings offer new insights into how spliceosome dynamics and component interactions dictate alternative splicing outcomes.
• Understanding these intricate splicing regulatory networks can pave the way for novel therapeutic strategies targeting diseases associated with splicing defects.