Ionizing Radiation Actively Reshapes Bone Marrow-Derived Extracellular Vesicle MicroRNA Cargo with the Involvement of hnRNP A2b1.

Bone marrow (BM) is highly sensitive to ionizing radiation: high doses cause extensive cell death, BM failure, and immune suppression, whereas low doses may increase long-term cancer risk without acute toxicity. Radiation-induced BM effects are partly mediated by disrupted intercellular communication via extracellular vesicles (EVs), including alterations in their microRNA cargo. EV-microRNA packaging remains unclear, although RNA-binding proteins are thought to contribute. To address this, murine BM cells and EVs were isolated 24 h after total body irradiation (0, 0.1, or 3 Gy). MicroRNAs were analyzed using nCounter and validated by RT-qPCR, while RNA-binding proteins (hnRNP A2b1, hnRNP Q) were assessed by Western blotting and confocal microscopy. Protein-microRNA interactions were examined using motif analysis and immunoprecipitation, and functional associations were explored via KEGG pathway analysis. High-dose irradiation induced widespread microRNA changes, whereas low-dose irradiation had minimal effects. Distinct cellular and EV microRNA profiles indicated selective sorting, with specific microRNAs enriched in cells but depleted in EVs. hnRNP A2b1 emerged as a potential regulator, showing nuclear relocalization and reduced EV association after irradiation; these changes correlated with decreased export of motif-containing microRNAs, possibly linked to key BM pathways. Overall, radiation alters EV-microRNAs through dose-dependent, protein-mediated selective sorting, potentially affecting BM communication and homeostasis.