Systematic mapping of small nucleolar RNA interactions in human cells

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Altered expression of box C/D small nucleolar RNAs (snoRNAs) is linked to human diseases like cancer.
• While canonically directing 2'-O-methylation, the full functional repertoire of snoRNAs remains largely unexplored.

Purpose of the Study:

• To comprehensively identify RNA interactions of box C/D snoRNAs in human cells.
• To explore novel functions of snoRNAs beyond their canonical role in RNA methylation.

Main Methods:

• Utilized UV crosslinking, proximity ligation, and sequencing of RNA hybrids (CLASH and FLASH) to map snoRNA interactions.
• Developed a bioinformatics pipeline for rigorous identification and analysis of snoRNA-RNA interactions.
• Performed U3 snoRNA depletion experiments to assess functional consequences of snoRNA-mRNA interactions.

Main Results:

• Identified hundreds of novel interactions between snoRNAs and rRNA, other snoRNAs, and mRNAs.
• Discovered numerous snoRNA-rRNA interactions not predicted to direct methylation, suggesting roles in ribosome biogenesis.
• Documented extensive snoRNA-mRNA interactions, with U3 snoRNA showing unique binding patterns and functional impact upon depletion.
• Observed enrichment of snoRNA association with intronic regions, indicating regulation of snoRNA maturation.

Conclusions:

• Box C/D snoRNAs engage in diverse RNA interactions, extending their known functions beyond methylation.
• These novel interactions may play significant roles in gene regulation, RNA processing, and cellular function.
• Findings provide a foundation for understanding snoRNA contributions to human health and disease.