| Objective To explore the mechanism of low-intensity pulsed ultrasound (LIPUS) in promoting bone formation, and to find potential valuable molecular targets for the treatment of osteoporosis. Methods Osteoblasts were divided into LIPUS group and Control group. After being irradiated with LIPUS for 1h, 6h, 12h, 18h, 24h, and 36h, the cell proliferation viability of the two groups was detected with CCK-8 assay. The expression level of PIEZO1 protein in the two groups was detected with Western blotting. Then the osteoblasts were divided into Control group, LIPUS group, LIPUS+GsMTx4 group, and GsMTx4 group. After intervention, Western blotting was used to detect the expression levels of p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR, and Cyclin D1 in each group. Results CCK-8 results suggested that LIPUS significantly promoted the proliferation of MC3T3-E1 osteoblasts. The expression levels of PIEZO1 and Cyclin D1 in the LIPUS group were significantly higher than those in the Control group (P<0.001), which indicated that LIPUS promoted the proliferation of MC3T3-E1 osteoblasts by up-regulating the expression of PIEZO1. In the mechanism assay, it was found that the expression levels of p-PI3K, p-AKT, p-mTOR, and Cyclin D1 in the LIPUS group were significantly higher than those in the Control group (P<0.001). The expression levels of p-PI3K, p-AKT, p-mTOR, and Cyclin D1 were significantly lower in the GsMTx4 group than those in the Control group (P<0.001), and were significantly lower in the LIPUS+GsMTx4 group than in the LIPUS group (P<0.001). Conclusion LIPUS promotes the proliferation of MC3T3-E1 osteoblasts by promoting the expression of PIEZO1 to activate the PI3K/AKT/mTOR signaling pathway. |