Mechanical stress up-regulates RANKL expression via the VEGF autocrine pathway in osteoblastic MC3T3-E1 cells
Mechanical stress up-regulates RANKL expression via the VEGF autocrine pathway in osteoblastic MC3T3-E1 cells
复制标题
DOI：
10.3892/mmr_00000088
复制
发表时间：
2009-03-01
影响因子：
3.4
通讯作者：
Iida, Junichiro
中科院分区：
文献类型：
--
作者：
Nakai, Takeshi;Yoshimura, Yoshitaka;Iida, Junichiro
尽管已有报道血管内皮生长因子（VEGF）不仅促进血管生成，而且促进破骨细胞和成骨细胞分化，但很少有关于成骨细胞中VEGF/VEGF受体（VEGFR）信号传导的报道，其调节破骨细胞分化并产生VEGF。本研究检测了骨重建因子VEGF-A及其受体VEGFR-1（Flt-1）和VEGFR-2（Flk-1/KDR）在小鼠成骨细胞MC 3 T3-E1细胞中的表达。机械应力组VEGF-A蛋白含量较对照组明显升高，而巨噬细胞集落刺激因子蛋白含量较对照组明显降低。成骨细胞MC 3 T3-E1未见VEGFR-2 mRNA表达。机械应力上调VEGF-A、VEGFR-1和核因子-κ B配体受体激活因子（RANKL）mRNA表达。特别是，VEGF-A和RANKL mRNA表达增加后立即机械应力。我们研究了VEGF/VEGFR系统对机械应力下成骨细胞中抗小鼠VEGF中和抗体的影响。与非机械应力组相比，VEGF中和抗体部分抑制了VEGF-A和RANKL mRNA表达的增加。VEGFR-1 mRNA表达被VEGF中和抗体完全抑制至对照水平。这些结果表明，机械应力通过成骨细胞MC 3 T3-E1中的VEGF/VEGFR-1自分泌途径上调RANKL表达，表明成骨细胞在响应机械应力时可能通过VEGF/VEGFR-1和RANKL表达的自分泌上调来增加骨吸收。
Although it has been reported that vascular endothelial growth factor (VEGF) promotes not only angiogenesis but also osteoclast and osteoblast differentiation, few reports exist regarding VEGF/VEGF receptor (VEGFR) signaling in osteoblasts, which regulate osteoclast differentiation and generate VEGF. This study examined the expression of the bone remodeling factor VEGF-A and its receptors, VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR), in murine osteoblastic MC3T3-E1 cells with the application of mechanical stress. The protein concentration of VEGF-A in the mechanical stress group increased markedly compared with the control group, while that of macrophage colony-stimulating factor in the mechanical stress group was lower than in the control group. VEGFR-2 mRNA expression was not detected in osteoblastic MC3T3-E1 cells. Mechanical stress up-regulated VEGF-A, VEGFR-1 and the receptor activator of nuclear factor-kappa B ligand (RANKL) mRNA expression. In particular, VEGF-A and RANKL mRNA expression increased immediately after mechanical stress. We examined the VEGF/VEGFR system on anti-mouse VEGF neutralizing antibody in osteoblasts with mechanical stress. Neutralizing antibody to VEGF partially inhibited the increase of VEGF-A and RANKL mRNA expression compared with the non-mechanical stress group. VEGFR-1 mRNA expression was completely suppressed to control levels by the neutralizing antibody to VEGF. These findings suggest that mechanical stress up-regulates RANKL expression via the VEGF/VEGFR-1 autocrine pathway in osteoblastic MC3T3-E1 cells, indicating the possibility that, in response to mechanical stress, osteoblasts increase bone resorption by an autocrine up-regulation of VEGF/VEGFR-1 and RANKL expression.