Schmid C, Keller C, Schläpfer I, Veldman C, Zapf J
Division of Endocrinology and Diabetes, Department of Internal Medicine, University Hospital, Zürich, CH-8091, Switzerland.
Biochem Biophys Res Commun. 1998 Apr 7;245(1):220-5. doi: 10.1006/bbrc.1998.8403.
Calcium (Ca) stimulates proliferation of osteoblasts in vitro, an effect proposed to be mediated by IGF I. Addition of 1 mM Ca or of 1 nM IGF I to the medium (0.3 mM Ca) of a rat bone-derived cell line, PyMS, stimulated not only DNA synthesis but also sodium-dependent (Nad) phosphate (Pi) uptake, the latter, within 2 h. These cells barely express and produce IGF I. IGF binding protein-3 which inhibits IGF action decreased neither basal nor Ca-stimulated but IGF I-stimulated NadPi transport and DNA synthesis, indicating that Ca stimulated NadPi transport and DNA synthesis independently of IGF I. The effects of Ca and IGF I on DNA synthesis were additive. 1 microM nifedipine blocked IGF I- and Ca-stimulated DNA synthesis but not NadPi transport, suggesting that Ca influx is not mediating the NadPi transport-enhancing IGF I signal but is required for IGF I-induced osteoblast proliferation.
钙（Ca）在体外刺激成骨细胞增殖，这一效应被认为是由胰岛素样生长因子I（IGF I）介导的。向大鼠骨源细胞系PyMS的培养基（0.3 mM钙）中添加1 mM钙或1 nM IGF I，不仅刺激了DNA合成，还刺激了钠依赖性（Nad）磷酸盐（Pi）摄取，后者在2小时内发生。这些细胞几乎不表达和产生IGF I。抑制IGF作用的IGF结合蛋白-3既不降低基础状态下的，也不降低钙刺激的，但能降低IGF I刺激的NadPi转运和DNA合成，这表明钙刺激NadPi转运和DNA合成独立于IGF I。钙和IGF I对DNA合成的作用是相加的。1 microM硝苯地平阻断了IGF I和钙刺激的DNA合成，但不阻断NadPi转运，这表明钙内流不是介导增强NadPi转运的IGF I信号所必需的，但却是IGF I诱导成骨细胞增殖所必需的。
