2022, Vol. 26 ›› Issue (11): 1686-1691
The mechanism by which bone morphogenetic protein 2 indirectly regulates sclerostin expression in osteocytes
Bone morphogenetic protein 2 (BMP-2) can promote osteogenesis, and osteocytes secrete sclerostin by expressing SOST gene to inhibit the osteogenic effect of osteoblasts. Some studies have found that BMPs family can promote the secretion of osteosclerotic protein when directly acting on osteocytes, but this contradicts the positive osteogenic effect of BMPs.
To explore the mechanism of BMP-2 indirectly regulating the expression of sclerostin gene in osteocytes.
Mouse MC-3T3-E1 cells were treated with different concentrations of BMP-2 (4, 8, 16, 32, 64, 125, 250, 500 and 1 000 μg/L) in vitro. The best concentration of BMP-2 to promote the proliferation of MC-3T3-E1 cells was detected by cell counting kit-8. Then the effect of BMP-2 on the indirect regulation of sclerostin gene expression in osteocytes was studied by co-culture of MC-3T3-E1 cells and MLO-Y4 cells. The possible altered genes in MC-3T3-E1 cells were detected by RT-PCR, and the target genes of MC-3T3-E1 cells were screened to verify the effect of target genes on the expression of sclerostin in MLO-Y4 cells.
BMP-2 could significantly promote the proliferation of osteoblasts. Compared with other concentrations, 250 μg/L had the best effect. The results of RT-PCR experiment showed that BMP-2 could indirectly regulate the expression of sclerostin gene and promote the down-regulation of sclerostin expression in osteocytes (P < 0.01). The results of target gene screening showed that, compared with other genes, the expression of receptor activator of nuclear factor-κB ligand in osteoblasts was significantly downregulated and the expression of osteoprotegerin in osteoblasts was significantly upregulated (P < 0.01). The results of target gene verification showed that BMP-2 may indirectly affect the expression of osteoprotegerin and receptor activator of nuclear factor-κB ligand in osteocytes, and then affect the expression of sclerostin in MLO-Y4 cells, thus positively promoting osteogenesis.
Sclerostin, SOST, bone morphogenetic protein 2, osteocyte, osteoblast