Exomeres and Supermeres: monolithic or diverse?

Area of Science:

• Extracellular biology
• Molecular and Cellular Biology
• Biochemistry

Background:

• Extracellular vesicles (EVs), exosomes, and microvesicles are known RNA carriers.
• New extracellular particles (EPs) including exomeres and supermeres have been recently identified.
• Supermeres are RNA-rich EPs implicated in disease biomarkers and cellular changes.

Purpose of the Study:

• To investigate the molecular composition of exomeres and supermeres.
• To gain insights into the nature of extracellular RNA (exRNA) carriers.
• To understand the origin and protection mechanisms of exRNAs within EPs.

Main Methods:

• Reanalysis of proteomic and transcriptomic data from previous studies.
• Bioinformatic analysis to identify RNA and protein components.
• Comparison of molecular signatures of exomeres and supermeres.

Main Results:

• Supermeres' top RNAs are footprints of extracellular protein complexes.
• These complexes protect RNA fragments, including U2 small nuclear RNA and 28S rRNA, from exoribonucleases (exRNases).
• Intracellular nanoparticles like U2 ribonucleoprotein and ribosomes may be released and contribute to EPs.

Conclusions:

• Supermeres contain RNA protected by protein complexes, suggesting a novel EP class.
• Extracellular ribonucleases (exRNases) play a role in processing EPs.
• Further research is needed to define exRNA carriers, their composition, and function.