Lomri A, Marie P J
Unité 18 INSERM, Hôpital Lariboisière Paris, France.
Biochim Biophys Acta. 1988 Jul 29;970(3):333-42. doi: 10.1016/0167-4889(88)90133-4.
Parathyroid hormone (PTH) has been shown to cause transient cell shape changes in bone cells. We have examined the effects of parathyroid hormone and forskolin on the organization and expression of cytoskeletal proteins in cultured mouse endosteal osteoblastic cells. Analysis of [35S]methionine-labeled cytoskeletal proteins isolated on two-dimensional gel electrophoresis showed that PTH treatment (24 h) stimulated the de novo biosynthesis of actin, vimentin and tubulins in confluent cells, whereas forskolin had a minor effect despite a huge stimulation of cAMP production. This PTH-induced stimulation was associated with cell respreading following a mild and transitory cell retraction. PTH increased the synthesis of monomeric subunits of actin and beta-tubulins in subconfluent bone cells, whereas both monomeric and polymeric levels of beta-tubulins were increased in confluent osteoblasts. Under conditions reducing cell spreading, osteoblastic cells had initially high levels of unpolymerized subunits. In these poorly spread cells, parathyroid hormone or forskolin had no effect on the de novo synthesis of cytoskeletal proteins despite a marked elevation in intracellular cAMP levels. It is concluded that PTH affects the biosynthesis of cytoskeletal proteins in osteoblastic cells and that cAMP production does not seem to be directly involved. In addition, the effect of PTH is modulated by cell spreading and by the initial pool of cytoskeletal subunits.
甲状旁腺激素（PTH）已被证明可引起骨细胞短暂的细胞形态变化。我们研究了甲状旁腺激素和福斯高林对培养的小鼠骨内膜成骨细胞中细胞骨架蛋白的组织和表达的影响。对通过二维凝胶电泳分离的[35S]甲硫氨酸标记的细胞骨架蛋白的分析表明，PTH处理（24小时）刺激了汇合细胞中肌动蛋白、波形蛋白和微管蛋白的从头生物合成，而福斯高林尽管极大地刺激了cAMP的产生，但影响较小。这种PTH诱导的刺激与轻度且短暂的细胞回缩后的细胞重新铺展有关。PTH增加了亚汇合骨细胞中肌动蛋白和β-微管蛋白单体亚基的合成，而在汇合的成骨细胞中，β-微管蛋白的单体和聚合物水平均增加。在减少细胞铺展的条件下，成骨细胞最初具有高水平的未聚合亚基。在这些铺展不佳的细胞中，甲状旁腺激素或福斯高林对细胞骨架蛋白的从头合成没有影响，尽管细胞内cAMP水平显著升高。结论是，PTH影响成骨细胞中细胞骨架蛋白的生物合成，并且cAMP的产生似乎没有直接参与。此外，PTH的作用受细胞铺展和细胞骨架亚基的初始储备调节。
