NADPH oxidase activation increases the sensitivity of intracellular Ca2+ stores to inositol 1,4,5-trisphosphate in human endothelial cells
NADPH oxidase activation increases the sensitivity of intracellular Ca2+ stores to inositol 1,4,5-trisphosphate in human endothelial cells
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DOI：
10.1074/jbc.m000381200
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发表时间：
2000-05-26
影响因子：
4.8
通讯作者：
Ziegelstein, RC
中科院分区：
文献类型：
--
作者：
Hu, QH;Zheng, GM;Ziegelstein, RC
许多激活血管NADPH氧化酶的刺激物产生活性氧并增加细胞内Ca 2+，但NADPH氧化酶激活是否直接影响Ca 2+信号尚不清楚。NADPH刺激人主动脉内皮细胞中超氧阴离子和H2 O2的产生，而这种产生受到NADPH氧化酶抑制剂二苯碘铵的抑制，并且在短暂表达小ATP结合蛋白Rad的显性负等位基因的细胞中显着减弱，而Rad是氧化酶活性所需的。在透化的Mag-indo 1负载细胞中，NADPH和H2 O2均降低释放胞内储存的Ca 2+所需的1，4，5-三磷酸肌醇（InsP（3））的阈值浓度，并使InsP（3）-Ca 2+释放量-反应曲线左移，低至3 μ M的H2 O2浓度增加了细胞内钙库对InsP（3）的敏感性，并使InsP（3）的EC 50从423.2 +/-54.9至276.9 +/- 14.4 nM。NADPH对InsP（3）刺激的Ca 2+释放的影响被过氧化氢酶和二苯碘鎓阻断，在缺乏功能性Rac 1蛋白的细胞中未观察到。因此，NADPH氧化酶衍生的H2 O2增加了人内皮细胞内Ca 2+储存对InsP（3）的敏感性。由于Ca 2+依赖性信号通路对正常内皮功能至关重要，因此这种作用在内皮信号转导中可能非常重要。
Many stimuli that activate the vascular NADPH oxidase generate reactive oxygen species and increase intracellular Ca2+, but whether NADPH oxidase activation directly affects Ca2+ signaling is unknown. NADPH stimulated the production of superoxide anion and H2O2 in human aortic endothelial cells that was inhibited by the NADPH oxidase inhibitor diphenyleneiodonium and was significantly attenuated in cells transiently expressing a dominant negative allele of the small GTP-binding protein Rad, which is required for oxidase activity. In permeabilized Mag-indo 1-loaded cells, NADPH and H2O2 each decreased the threshold concentration of inositol 1,4,5-trisphosphate (InsP(3)) required to release intracellularly stored Ca2+ and shifted the InsP(3)-Ca2+ release dose-response curve to the left, Concentrations of H2O2 as low as 3 mu M increased the sensitivity of intracellular Ca2+ stores to InsP(3) and decreased the InsP(3) EC50 from 423.2 +/- 54.9 to 276.9 +/- 14.4 nM. The effect of NADPH on InsP(3)-stimulated Ca2+ release was blocked by catalase and by diphenyleneiodonium and was not observed in cells lacking functional Rac1 protein. Thus, NADPH oxidase-derived H2O2 increases the sensitivity of intracellular Ca2+ stores to InsP(3) in human endothelial cells. Since Ca2+-dependent signaling pathways are critical to normal endothelial function, this effect may be of great importance in endothelial signal transduction.