Decreased endothelial nitric-oxide synthase (eNOS) activity resulting from abnormal interaction between eNOS and its regulatory proteins in hypoxia-induced pulmonary hypertension
Decreased endothelial nitric-oxide synthase (eNOS) activity resulting from abnormal interaction between eNOS and its regulatory proteins in hypoxia-induced pulmonary hypertension
复制标题
DOI：
10.1074/jbc.m205934200
复制
发表时间：
2002-11-15
影响因子：
4.8
通讯作者：
Karaki, H
中科院分区：
文献类型：
--
作者：
Murata, T;Sato, K;Karaki, H
在1周缺氧诱导的肺动脉高压大鼠的肺动脉中，卡巴胆碱刺激的内皮NO产生显着减少，在原位可视化使用二氨基荧光素-2二乙酸酯和cGMP含量。这种变化之后是卡巴胆碱诱导的内皮依赖性舒张的减少。内皮型一氧化氮合酶（eNOS）及其调节蛋白小窝蛋白-1和热休克蛋白90的蛋白表达在低氧肺动脉中没有改变，表明慢性低氧在翻译后水平损害eNOS活性。在缺氧的肺动脉中，细胞内Ca ~（2+）水平的增加由卡巴胆碱刺激，但不是由离子霉素减少。我们接下来关注eNOS激活系统的Ca 2+敏感性的变化。形态学研究显示，内皮细胞萎缩和内皮型一氧化氮合酶在缺氧内皮细胞中的外周浓缩，保持内皮型一氧化氮合酶和高尔基体或质膜之间的共定位。然而，eNOS与小窝蛋白-1紧密偶联，并且在存在或不存在卡巴胆碱的情况下从缺氧肺动脉中的热休克蛋白90或钙调素中解离。此外，eNOS Ser（1177）磷酸化在两种条件下均显著降低，而不影响缺氧动脉中Akt磷酸化。总之，慢性缺氧损害内皮细胞Ca 2+代谢和eNOS和小窝蛋白-1之间的正常耦合导致eNOS失活。
In the pulmonary artery isolated from 1-week hypoxia-induced pulmonary hypertensive rats, endothelial NO production stimulated by carbachol was decreased significantly in in situ visualization using diaminofluorescein-2 diacetate and also in cGMP content. This change was followed by the decrease in carbachol-induced endothelium-dependent relaxation. Protein expression of endothelial NO synthase (eNOS) and its regulatory proteins, caveolin-1 and heat shock protein 90, did not change in the hypoxic pulmonary artery, indicating that chronic hypoxia impairs eNOS activity at posttranslational level. In the hypoxic pulmonary artery, the increase in intracellular Ca2+ level stimulated by carbachol but not by ionomycin was reduced. We next focused on changes in Ca2+ sensitivity of the eNOS activation system. A morphological study revealed atrophy of endothelial cells and a peripheral condensation of eNOS in hypoxic endothelial cells preserving co-localization between eNOS and Golgi or plasma membranes. However, eNOS was tightly coupled with caveolin-1, and was dissociated from heat shock protein 90 or calmodulin in the hypoxic pulmonary artery in either the presence or absence of carbachol. Furthermore, eNOS Ser(1177) phosphorylation in both conditions significantly decreased without affecting Akt phosphorylation in the hypoxic artery. In conclusion, chronic hypoxia impairs endothelial Ca2+ metabolism and normal coupling between eNOS and caveolin-1 resulted in eNOS inactivity.