MiR-140-3p directly targets Tyro3 to regulate OGD/R-induced neuronal injury through the PI3K/Akt pathway

MicroRNAs (miRNAs) are highly expressed in the central nervous system and play important roles in ischaemic stroke pathogenesis. However, the role of miRNAs in cerebral ischaemia-reperfusion injury remains unclear. Here, we investigated the role of miR-140-3p in regulating oxygen-glucose deprivation/reoxygenation (OGD/R)-induced neuronal injury in vitro to identify a new biomarker for research on ischaemic stroke.

The differential expression of miR-140-3p and Tyro3 in OGD/R-exposed N2a cells was verified by qRT-PCR. N2a cells were transfected with miR-140-3p mimic, miR-140-3p inhibitor, Tyro3 or siTyro3, and qRT-PCR, Western blotting, the Cell counting kit-8 (CCK-8) assay, Hoechst 33342/PI staining and flow cytometry analyses were performed to measure miRNA, mRNA and protein expression; cell viability; and apoptosis.

OGD/R-exposed N2a cells exhibited increased miR-140-3p expression, decreased viability, reduced Bcl-2 protein expression and increased Bax and Caspase-3 protein expression and apoptosis; the miR-140-3p mimic markedly amplified these changes, exacerbating OGD/R-induced injury to N2a cells, while the miR-140-3p inhibitor reversed these changes and alleviated OGD/R-induced injury. OGD/R-exposed N2a cells expressed less Tyro3, and Tyro3 overexpression increased cell viability and Bcl-2 protein expression, reduced Bax and Caspase-3 protein expression, and alleviated OGD/R-induced injury. However, silencing Tyro3 reversed these changes and exacerbated OGD/R-induced injury. MiR-140-3p directly bound the Tyro3 mRNA 3'UTR. Rescue experiments indicated that the miR-140-3p mimic-induced changes in cell viability and protein expression were alleviated by Tyro3 overexpression and that the miR-140-3p inhibitor-induced changes in cell viability and protein expression were alleviated by silencing Tyro3. Tyro3 overexpression increased cell viability and PI3K and p-Akt protein expression, but these effects were weakened by the addition of LY294002.

MiR-140-3p directly targets Tyro3 to regulate cell viability and apoptosis of OGD/R-exposed N2a cells through the PI3K/Akt pathway, suggesting that miR-140-3p is a novel biomarker and therapeutic target for ischaemic stroke.