流体切应力下SIVA-1凋亡诱导因子促成骨细胞增殖分化的双向调节作用

目的探讨流体切应力（fluid shear stress,FSS）对KM小鼠成骨细胞增殖分化及相关细胞凋亡诱导因子（SIVA-1）的调节作用。方法将传至3代成骨细胞分为应力刺激组（试验组）和非应力刺激组（对照组）。5个试验组分别给予1.2PaFSS作用0.25,0.5,1,2,4h;对照组为0h。MTT法测定细胞增殖,检测碱性磷酸酶（ALP）活性,半定量RT-PCR测定凋亡诱导因子SIVA-1的表达水平。结果FSS促增殖作用在短期（0.25,0.5h）明显,且细胞生长曲线前移;但在1,2,4h却有明显抑制增殖作用。FSS同样增加了ALP活性,尤其在应力作用0.5h时显著（ALP含量为2.4320±0.205金氏单位/100ml,相对对照达158%）（P〈0.05）;而应力作用1,2,4h后减低了ALP的表达。应力初期SIVA-1mRNA表达量明显下降,尤其在FSS作用0.5h后SIVA-1/GAPDH相对表达量为0.099±0.002,相对对照明显下调了71.3%（P〈0.01）,此效应在作用1h后减退,SIVA-1mRNA表达开始升高,4h后升高明显。结论1.2PaFSS在短时间刺激下可刺激成骨细胞增殖分化,尤其在0.5h后效应明显。早期促细胞增殖和ALP水平升高主要与SIVA-1mRNA表达下调有关,而后期抑制作用可能与SIVA-1mRNA表达升高有关。

Two-way Regulation of Apoptosis-inducing Factor SIVA-1 in the Proliferation and Differentiation of Osteoblasts under Fluid Shear Stress

Objective To investigate the regulatory effect of fluid shear stress （FSS） on the proliferation and differentiation of osteoblasts, as well as the expression of apoptosis-inducing factor, SIVA-1. Methods The third-passage osteoblasts were divided into five experiment groups and one control group. In the experiment groups, 1.2 Pa FSS were given to the osteoblasts for 0.25, 0.5, 1, 2, and 4 hours respectively, while the control group received no FSS. Afterwards, the cells were harvested to measure MTT value and ALP activity; mRNA level of SIVA-1 were determined by RT-PCR. Results MTT revealed that the cells proliferation markedly increased in the 0.25 h and 0.5 h experiment groups with advanced cell growth curve; whereas significantly inhibited in 1, 2, and 4 h groups. The FSS also increased the ALP activity at 0.25 and 0.5 hour, especially in the 0.5 h group （2. 4320± 0. 205 S unit/100ml, 158% of the control; P 〈 0.05） , while at the 1, 2 and 4 h groups, the expression of ALP deceased significantly. The SIVA-1 mRNA expression decreased as a result of short-time FSS, the relative expression of SIVA-1/GAPDH is 0. 099±0. 002 at 0.5 hour （decreased by 71.3% compared with the control, P 〈 0.01 ）. The expression began to increase at 1 hour, and then increased significantly at 4 hours. Conclusions 1.2 Pa FSS can enhance the proliferation and differentiation of osteoblasts at the early period; the efficacy is especially significant at0. 5 hour. The enhanced proliferation and increased ALP activity at early stage is related to the down-regulation of SIVA-1 expression, and the inhibitory effect in the late state may be associated with the increased expression of SIVA-1.