Thomas D M, Rogers S D, Sleeman M W, Pasquini G M, Bringhurst F R, Ng K W, Zajac J D, Best J D
University of Melbourne Department of Medicine, St Vincent's Hospital, Fitzroy, Victoria, Australia.
J Mol Endocrinol. 1995 Apr;14(2):263-75. doi: 10.1677/jme.0.0140263.
This study characterizes the actions of insulin and parathyroid hormone (PTH) on the glucose transport system in the rat osteogenic sarcoma cell line UMR 106-01, which expresses a number of features of the osteoblast phenotype. Using [1,2-3H]2-deoxyglucose (2-DOG) as a label, UMR 106-01 cells were shown to possess a glucose transport system which was enhanced by insulin. In contrast, PTH influenced glucose transport in a biphasic manner with a stimulatory effect at 1 h and a more potent inhibitory effect at 16 h on basal and insulin-stimulated 2-DOG transport. To explore the mechanism of PTH action, a direct agonist of cAMP-dependent protein kinase (PKA) was tested. 8-Bromo-cAMP had no acute stimulatory effect but inhibited basal and insulin-stimulated 2-DOG transport at 16 h. This result suggested that the prolonged, but not the acute, effect of PTH was mediated by the generation of cAMP. Further studies with the cell line UMR 4-7, a UMR 106-01 clone stably transfected with an inducible mutant inactive regulatory subunit of PKA, confirmed that the inhibitory but not the stimulatory effect of PTH was mediated by the PKA pathway. Northern blot data indicated that the prolonged inhibitory effects of PTH and 8-bromo-cAMP on glucose transport were likely to be mediated in part by reduction in the levels of GLUT1 (HepG2/brain glucose transporter) mRNA.
本研究描述了胰岛素和甲状旁腺激素（PTH）对大鼠骨肉瘤细胞系UMR 106 - 01中葡萄糖转运系统的作用，该细胞系表现出许多成骨细胞表型特征。以[1,2 - 3H]2 - 脱氧葡萄糖（2 - DOG）作为标记物，研究表明UMR 106 - 01细胞拥有一个可被胰岛素增强的葡萄糖转运系统。相比之下，PTH对葡萄糖转运的影响呈双相性，在1小时时有刺激作用，而在16小时时对基础和胰岛素刺激的2 - DOG转运有更强的抑制作用。为探究PTH作用的机制，对一种环磷酸腺苷（cAMP）依赖性蛋白激酶（PKA）的直接激动剂进行了测试。8 - 溴 - cAMP没有急性刺激作用，但在16小时时抑制基础和胰岛素刺激的2 - DOG转运。该结果表明，PTH的长期而非急性作用是由cAMP的生成介导的。对UMR 4 - 7细胞系（一种稳定转染了可诱导的突变失活PKA调节亚基的UMR 106 - 01克隆）的进一步研究证实，PTH的抑制作用而非刺激作用是由PKA途径介导的。Northern印迹数据表明，PTH和8 - 溴 - cAMP对葡萄糖转运的长期抑制作用可能部分是由GLUT1（HepG2/脑葡萄糖转运体）mRNA水平的降低介导的。
