circRNA biogenesis competes with pre-mRNA splicing.

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Circular RNAs (circRNAs) are abundant noncoding RNAs with largely unknown biogenesis and functions.
• Understanding circRNA production and roles is crucial for molecular biology and genetics research.

Purpose of the Study:

• To investigate the mechanisms of animal circRNA biogenesis and their potential roles in gene regulation.
• To identify factors involved in circRNA production and function.

Main Methods:

• Identification and analysis of circRNAs in neuronal tissues.
• Investigating the cotranscriptional generation of circRNAs.
• Studying the competition between circularization and linear splicing.
• Analyzing the role of muscleblind (MBL/MBNL1) in circRNA biosynthesis using conserved binding sites.

Main Results:

• Animal circRNAs are generated cotranscriptionally, with intronic sequences primarily determining production rates.
• Circularization and splicing are competing, tissue-specific, and conserved mechanisms.
• The muscleblind gene's second exon forms a circRNA (circMbl) that binds MBL, influencing its own biosynthesis.
• MBL levels and binding sites are critical for circMbl production.

Conclusions:

• CircRNAs can regulate gene expression by competing with linear splicing.
• Muscleblind (MBL/MBNL1) is identified as a key factor in circRNA biogenesis.
• These findings provide insights into the regulatory roles of circRNAs in animals.