Fig. 5

Restoration of Smad4 can rescue the effects of miR-3074-5p on MC3T3-E1 cells. A Gain- and loss-of-function experiments were performed by transfecting cells with pcDNA3.1-Smad4 and the miR-3074-5p mimic, respectively. The CCK-8 assay was used to evaluate the effect of Smad4 on cell viability. *P < 0.05 vs. the pcDNA3.1-NC. ^#P < 0.05 vs. the pcDNA3.1-NC + mimic group. B Apoptosis-related protein expression levels of cells were evaluated by western blot analysis. C Working model of miR-3074-5p-mediated apoptosis in iron-overloaded MC3T3-E1 cells. miR-3074-5p expression was significantly increased in MC3T3-E1 cells under iron overload conditions. Overexpression of miR-3074-5p induced downregulation of Smad4, the knockdown of which inhibited ERK, AKT and Stat3 phosphorylation, resulting in apoptosis