Caveolin-1 selectively regulates microRNA sorting into microvesicles after noxious stimuli

Area of Science:

• Cell Biology
• Molecular Biology
• Immunology

Background:

• Extracellular vesicles (EVs), particularly microvesicles (MVs), mediate intercellular communication via miRNA transfer.
• The precise mechanisms by which cells selectively package miRNAs into EVs remain largely unknown.
• Understanding miRNA sorting into EVs is crucial for deciphering cellular responses to stimuli.

Purpose of the Study:

• To identify the key protein involved in sorting specific miRNAs into microvesicles (MVs).
• To elucidate the molecular mechanism by which oxidative stress influences miRNA packaging into MVs.
• To investigate the functional consequences of MV-mediated miRNA transfer in the lung.

Main Methods:

• Investigated the role of caveolin-1 (cav-1) in miRNA sorting into MVs.
• Utilized co-immunoprecipitation and Western blotting to analyze protein-protein and protein-RNA interactions.
• Examined the effects of oxidative stress and post-translational modifications (phosphorylation, O-GlcNAcylation) on miRNA packaging.
• Assessed the functional impact of MV-derived miRNAs on recipient macrophages.

Main Results:

• Caveolin-1 (cav-1) was identified as essential for sorting specific miRNAs into MVs.
• Cav-1 tyrosine 14 (Y14)-phosphorylation facilitates interaction with RNA-binding protein hnRNPA2B1, forming a complex that traffics into MVs.
• Oxidative stress induces hnRNPA2B1 O-GlcNAcylation, altering the miRNA repertoire within MVs; cav-1 pY14 promotes this modification.
• Epithelial MVs containing the cav-1/hnRNPA2B1 complex and specific miRNAs (miR-17/93) activate lung tissue macrophages, indicating an innate immune response.

Conclusions:

• Caveolin-1 (cav-1) is the first identified membranous protein that directly mediates the sorting of RNA-binding proteins into EVs.
• A novel mechanism is described where oxidative stress prompts epithelial cells to package and secrete specific miRNAs via MVs.
• This process elicits an innate immune response through the activation of tissue macrophages by MV-derived miRNAs.