Martín M, Albasanz J L, Fernández M, Ros M
Area de Bioquímica, Facultad Ciencias Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela, 10, CP 13071, Ciudad Real, Spain.
Biochim Biophys Acta. 1998 Jul 31;1393(1):186-92. doi: 10.1016/s0005-2760(98)00036-8.
Exposure of rat C6 glioma cells to the beta-adrenergic receptor agonist isoproterenol potentiates basal and metabotropic glutamate receptor-stimulated phospholipase C activity in rat C6 glioma cells. After treatment of cells for 24 h with 10 microM isoproterenol, metabotropic glutamate receptors and phospholipase C activity were determined in C6 plasma membranes. Isoproterenol treatment caused an increase of 67% in the total number of binding sites (Bmax=12.1+/-1. 8 pmol/mg protein versus Bmax=20.27+/-0.88 pmol/mg protein) with Kd values of the same order (Kd=1250+/-101 nM versus Kd=1401+/-211 nM), using l-[3H]glutamate as radioligand. On the other hand, basal, guanylyl imidodiphosphate (Gpp[NH]p)- and trans-aminocyclopentane-1, 3-dicarboxylic acid (trans-ACPD)-stimulated phospholipase C activities were also significantly increased in membranes from isoproterenol-treated cells compared to control cells, by 337%, 33% and 40% respectively. Moreover, a significant increase of 94% in the steady-state level of phospholipase C beta1 in membranes from isoproterenol-treated cells compared to control was also detected by immunoblot. These results show that metabotropic glutamate receptors and its effector system, phospholipase C, are affected by isoproterenol treatment, showing the existence of cross-talk between these signal transduction pathways.
将大鼠C6胶质瘤细胞暴露于β-肾上腺素能受体激动剂异丙肾上腺素，可增强大鼠C6胶质瘤细胞中基础型和代谢型谷氨酸受体刺激的磷脂酶C活性。用10μM异丙肾上腺素处理细胞24小时后，测定C6质膜中的代谢型谷氨酸受体和磷脂酶C活性。以l-[3H]谷氨酸为放射性配体，异丙肾上腺素处理导致结合位点总数增加67%（Bmax = 12.1±1.8 pmol/mg蛋白，对照为Bmax = 20.27±0.88 pmol/mg蛋白），解离常数Kd值处于同一数量级（Kd = 1250±101 nM，对照为Kd = 1401±211 nM）。另一方面，与对照细胞相比，异丙肾上腺素处理细胞的质膜中基础型、鸟苷酰亚胺二磷酸（Gpp[NH]p）和反式-氨基环戊烷-1,3-二羧酸（反式-ACPD）刺激的磷脂酶C活性也显著增加，分别增加了337%、33%和40%。此外，通过免疫印迹法还检测到，与对照相比，异丙肾上腺素处理细胞的质膜中磷脂酶Cβ1的稳态水平显著增加了94%。这些结果表明，代谢型谷氨酸受体及其效应系统磷脂酶C受异丙肾上腺素处理的影响，表明这些信号转导途径之间存在相互作用。
