Pines M, Santora A, Gierschik P, Menczel J, Spiegel A
Molecular Pathophysiology Section, NIADDK, NIH, Bethesda, MD 20205.
Bone Miner. 1986 Feb;1(1):15-26.
We identified the subunits of the stimulatory and inhibitory guanine nucleotide binding proteins (Gs and Gi, respectively) associated with adenylate cyclase in rat osteosarcoma (ROS) cells. Pertussis toxin catalyzed ADP-ribosylation of Gi alpha in ROS cells increased agonist (PTH and isoproterenol)-stimulated, but not basal, cAMP production. The effect of pertussis toxin was dose and time dependent, and slowly reversible (T 1/2 approximately 30 h) during continued culture without toxin. Pertussis toxin treatment of ROS cell lines (17/2.8 and 24/l) with markedly different agonist responsiveness increased agonist-stimulated cAMP production in proportion to the response without toxin treatment. Pertussis toxin treatment further increased cAMP response to PTH in dexamethasone treated cells. We conclude that ROS cells contain functional Gi which modulates agonist-stimulated cAMP formation. Alterations in ROS cAMP responsiveness caused by steroids, and the reduced responsiveness of the 24/1 cell line, however, are unlikely to be due to changes in Gi.
我们鉴定了大鼠骨肉瘤（ROS）细胞中与腺苷酸环化酶相关的刺激性和抑制性鸟嘌呤核苷酸结合蛋白（分别为Gs和Gi）的亚基。百日咳毒素催化ROS细胞中Giα的ADP核糖基化增加了激动剂（甲状旁腺激素和异丙肾上腺素）刺激的而非基础的cAMP产生。百日咳毒素的作用呈剂量和时间依赖性，并且在无毒素的持续培养过程中缓慢可逆（半衰期约30小时）。用百日咳毒素处理具有明显不同激动剂反应性的ROS细胞系（17/2.8和24/1），激动剂刺激的cAMP产生与未处理毒素时的反应成比例增加。在用地塞米松处理的细胞中，百日咳毒素处理进一步增加了对甲状旁腺激素的cAMP反应。我们得出结论，ROS细胞含有功能性Gi，其调节激动剂刺激的cAMP形成。然而，类固醇引起的ROS cAMP反应性改变以及24/1细胞系反应性降低不太可能是由于Gi的变化。
