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首页> 外文期刊>American Journal of Physiology >Characterization of inorganic phosphate transport in osteoclast-like cells.
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Characterization of inorganic phosphate transport in osteoclast-like cells.

机译：破骨细胞样细胞中无机磷酸盐转运的特征。

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摘要

Osteoclasts possess inorganic phosphate (Pi) transport systems to take up external Pi during bone resorption. In the present study, we characterized Pi transport in mouse osteoclast-like cells that were obtained by differentiation of macrophage RAW264.7 cells with receptor activator of NF-kappaB ligand (RANKL). In undifferentiated RAW264.7 cells, Pi transport into the cells was Na+ dependent, but after treatment with RANKL, Na+-independent Pi transport was significantly increased. In addition, compared with neutral pH, the activity of the Na+-independent Pi transport system in the osteoclast-like cells was markedly enhanced at pH 5.5. The Na+-independent system consisted of two components with Km of 0.35 mM and 7.5 mM. The inhibitors of Pi transport, phosphonoformic acid, and arsenate substantially decreased Pi transport. The proton ionophores nigericin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone as well as a K+ ionophore, valinomycin, significantly suppressed Pi transport activity. Analysisof BCECF fluorescence indicated that Pi transport in osteoclast-like cells is coupled to a proton transport system. In addition, elevation of extracellular K+ ion stimulated Pi transport, suggesting that membrane voltage is involved in the regulation of Pi transport activity. Finally, bone particles significantly increased Na+-independent Pi transport activity in osteoclast-like cells. Thus, osteoclast-like cells have a Pi transport system with characteristics that are different from those of other Na+-dependent Pi transporters. We conclude that stimulation of Pi transport at acidic pH is necessary for bone resorption or for production of the large amounts of energy necessary for acidification of the extracellular environment.
机译：破骨细胞具有无机磷酸盐（Pi）传输系统，可在骨骼吸收过程中吸收外部Pi。在本研究中，我们表征了小鼠破骨细胞样细胞中的Pi转运，该细胞是通过用NF-κB配体的受体激活剂（RANKL）分化巨噬细胞RAW264.7细胞而获得的。在未分化的RAW264.7细胞中，Pi转运到细胞中是Na +依赖性的，但是用RANKL处理后，Na +依赖性的Pi转运会显着增加。另外，与中性pH相比，破骨细胞样细胞中Na +依赖性Pi运输系统的活性在pH 5.5下显着增强。不依赖Na +的系统由Km为0.35 mM和7.5 mM的两个组分组成。 Pi转运，膦酸甲酸和砷酸盐的抑制剂大大降低了Pi转运。质子离子载体尼古丁和羰基氰化物对三氟甲氧基苯基hydr以及K +离子载体瓦利诺霉素显着抑制了Pi的转运活性。 BCECF荧光分析表明，破骨细胞样细胞中的Pi转运与质子转运系统耦合。此外，细胞外K +离子的升高刺激了Pi的转运，表明膜电压参与Pi转运活性的调节。最后，在破骨细胞样细胞中，骨颗粒显着增加了不依赖Na +的Pi转运活性。因此，破骨细胞样细胞具有Pi转运系统，其特征不同于其他依赖Na +的Pi转运蛋白。我们得出结论，在酸性pH下刺激Pi转运对于骨骼吸收或产生细胞外环境酸化所需的大量能量是必需的。

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