Circular RNA landscape in extracellular vesicles from human biofluids.

Area of Science:

• Biochemistry
• Molecular Biology
• Genomics

Background:

• Circular RNAs (circRNAs) are covalently closed, single-stranded RNA molecules with tissue-specific expression.
• Extracellular vesicles (EVs) derived from liquid biopsies are promising sources for biomarker discovery.
• The characteristics and roles of circRNAs within EVs remain largely unexplored.

Purpose of the Study:

• To comprehensively analyze extracellular vesicle-derived circRNAs (EV-circRNAs) across diverse human biofluids.
• To investigate the potential of EV-circRNAs as biomarkers for disease diagnosis and treatment efficacy.
• To elucidate the mechanisms governing the sorting of circRNAs into EVs.

Main Methods:

• Transcriptomic analysis of 1082 human biofluid samples (plasma, urine, CSF, bile).
• Validation using RT-qPCR and RNA immunoprecipitation (RIP) assays.
• Computational analysis of EV-circRNA features and RNA-binding protein (RBP) interactions.

Main Results:

• Identification of 136,327 unique EV-circRNAs across human biofluids.
• High enrichment of circRNAs with high back-splicing ratios in EVs compared to linear RNAs.
• Discovery of brain-specific and cancer-associated EV-circRNAs, with potential for non-small cell lung cancer (NSCLC) immunotherapy efficacy assessment.
• Identification of YBX1 as a key RBP involved in EV-circRNA sorting.

Conclusions:

• This study reveals an extensive repertoire of EV-circRNAs with significant potential as disease biomarkers.
• Elucidation of RBP-mediated sorting mechanisms provides insights into EV-circRNA biogenesis.
• These findings open new avenues for the clinical application of EV-circRNAs in diagnostics and therapeutics.