Stretch-induced PTH-related protein gene expression in osteoblasts
Stretch-induced PTH-related protein gene expression in osteoblasts
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DOI：
10.1359/jbmr.2005.20.8.1454
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发表时间：
2005-08-01
影响因子：
6.2
通讯作者：
Broadus, AE
中科院分区：
文献类型：
--
作者：
Chen, XS;Macica, CM;Broadus, AE
简介：机械力对骨骼有合成代谢作用。已知PTH相关蛋白（PTHrP）基因在整个生物体的平滑肌细胞中是机械诱导的，并且已报道N-末端PTH和PTHrP产物在骨中具有合成代谢作用。我们探讨的想法，PTHrP可能是一个候选调解人的机械力对bone.Materials和Methods的影响：机械负荷施加膨胀成骨细胞样细胞在低渗溶液和/或通过应用程序的周期性拉伸通过FlexerCell设备。结果与结论：低渗溶液中肿胀牵张UMR 201 - 10 B成骨样细胞后PTHrP mRNA表达迅速增加。这种诱导是不敏感的钆和硝苯地平，细胞外钙的去除，并耗尽内质网钙，这表明既不拉伸激活阳离子通道，L-型钙通道，也不ER钙参与PTHrP的诱导。TREK家族钾通道被牵张和细胞内酸中毒激活，我们通过PCR在成骨细胞样细胞中鉴定了这些通道。细胞内酸化增加了UMR-201- 10 B细胞中PTHrP mRNA的表达，靶向TREK-2基因的siRNA降低了内源性TREK-2的表达并抑制了PTHrP mRNA的诱导。周期性拉伸还诱导UMR-201- 10 B成骨细胞样细胞和MLO-A5后成骨细胞-前骨细胞中的PTHrP，后者是成骨细胞分化程序中的一个阶段，可能是体内力的关键靶点。我们的证据表明PTHrP作为机械力对骨的合成代谢作用的候选介质。
Introduction: Mechanical force has anabolic effects on bone. The PTH-related protein (PTHrP) gene is known to be mechanically inducible in smooth muscle cells throughout the organism, and N-terminal PTH and PTHrP products have been reported to have anabolic effects in bone. We explored the idea that PTHrP might be a candidate mediator of the effects of mechanical force on bone.Materials and Methods: Mechanical loading was applied by swelling osteoblast-like cells in hypotonic solution and/or by application of cyclical stretch through a FlexerCell apparatus. RNase protection assay and real-time quantitative PCR analysis were used to assay PTHrP gene expression.Results and Conclusion: Stretching UMR201-10B osteoblast-like cells by swelling in hypotonic solutions rapidly increased PTHrP mRNA. This induction was insensitive to gadolinium and nifedipine, to the removal of extracellular calcium, and to depletion of endoplasmic reticulum calcium, indicating that neither stretch-activated cation channels, L-type calcium channels, nor ER calcium is involved in the induction of PTHrP. The TREK family potassium channels are activated by both stretch and intracellular acidosis, and we identified these channels in osteoblast-like cells by PCR. Intracellular acidification increased PTHrP mRNA expression in UMR-201-10B cells, and siRNA targeted against the TREK-2 gene reduced endogenous TREK-2 expression and dampened PTHrP mRNA induction. Cyclical stretch also induced PTHrP in UMR-201-10B osteoblast-like cells and in MLO-A5 post-osteoblast-pre-osteocyte cells, the latter a stage in the osteoblastic differentiation program that is likely to be a key target of force in vivo. Our evidence suggests PTHrP as a candidate mediator of the anabolic effects of mechanical force on bone.