PhD Scientific Days 2024

Pathological and Oncological Sciences II.

Identifying Extracellular vesicle-miRNAs with a possible role in ionizing radiation induced leukaemogenesis, and their EV packaging mechanisms in the bone marrow

Text of the abstract

Hematological malignancies identified as the primary long-term consequences of bone marrow (BM) irradiation, may be initiated by ionizing radiation (IR) induced BM-stem and progenitor cell damage, and altered intercellular signaling. One way of intercellular signaling and transmitting IR-induced damages between cells is through extracellular vesicles (EVs). We have previously shown in vivo that BM-EVs from irradiated mice initiate radiation induced bystander effect (RIBE) in the BM of naïve mice with the contribution of EV-miRNAs. We have also demonstrated that the combination of irradiation and EV treatment increased the frequency of AML in a murine model prone to radiation leukaemogenesis. To further understand EV-mediated IR effects on leukaemogenesis after irradiation, EV-cargo and it’s packaging were analyzed.
RNA-binding proteins (RBP) and miRNAs were analyzed in the BM and BM-derived-EVs of CBA mice isolated 24h after IR (0.1Gy,3Gy). Among the deregulated EV-miRNAs, AML, cellular senescence and inflammation related miRNAs were identified and linked to RBP through sequence motif analysis, interactions were validated with immunoprecipitation and qPCR.
71% of the EV-miRNAs associated with AML/senescence/inflammation were linked to three RBPs: Anxa2, hnRNpQ and hnNRPA2b1. Among them, hnRNPQ and hnRNPA2b1 expression altered upon IR. HnRNPA2b1 exhibited upregulation in the BM but downregulation in BM-EVs; the miRNAs carrying recognition motifs of hnRNPA2b1 mirrored the quantitative changes of their binding partner in EVs. We established the specific binding of miRNAs to hnRNPA2B1 through their binding motifs, as miRNAs lacking these motifs did not co-precipitate with the protein.
In summary, the miRNA content of BM-EVs following IR exposure results from a selective sorting and packaging mechanism. One observed mechanism through which IR influences this process is by deregulating RBPs. Selectively packaged EV-miRNAs associated with AML or related pathways contribute to AML development by influencing the BM microenvironment.
Funding: Euratom research and training programme 2014-2018 No662287 (CONCERT), HORIZON-EURATOM-2021-NRT-01 No101061037 (PIANOFORTE)