Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation
Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation
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DOI：
10.1038/21224
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发表时间：
1999-06-10
期刊：
影响因子：
64.8
通讯作者：
Zeiher, AM
中科院分区：
文献类型：
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作者：
Dimmeler, S;Fleming, I;Zeiher, AM
由内皮NO合酶（eNOS）产生的一氧化氮（NO）是心血管稳态的基本决定因素：它调节全身血压、血管重塑和血管生成（1-3）。在生理学上，NO连续形成的最重要刺激是由流动的血液在内皮层上产生的粘性阻力（剪切应力）（4-8）。虽然认为剪切应力介导的eNOS磷酸化调节酶活性（9，10），但eNOS活化的机制尚不清楚。在这里，我们证明了丝氨酸/苏氨酸蛋白激酶Akt/PKB（11-13）介导eNOS的激活，导致NO产生增加。抑制磷脂酰肌醇-3-OH激酶/Akt通路或突变eNOS蛋白上的Akt位点（在丝氨酸1177处）减弱丝氨酸磷酸化并阻止eNOS的活化。模拟丝氨酸1177的磷酸化直接增强酶活性并改变酶对Ca 2+的敏感性，使得其活性在亚生理浓度的Ca 2+下最大。因此，Akt对eNOS的磷酸化代表了一种新的eNOS激活的Ca 2+非依赖性调节机制。
Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) is a fundamental determinant of cardiovascular homesotasis: it regulates systemic blood pressure, vascular remodelling and angiogenesis(1-3). Physiologically, the most important stimulus for the continuous formation of NO is the viscous drag (shear stress) generated by the streaming blood on the endothelial layer(4-8). Although shear-stress-mediated phosphorylation of eNOS is thought to regulate enzyme activity(9,10), the mechanism of activation of eNOS is not yet known. Here we demonstrate that the serine/threonine protein kinase Akt/PKB (11-13) mediates the activation of eNOS, leading to increased NO production. Inhibition of the phosphatidylinositol-3-OH kinase/Akt pathway or mutation of the Akt site on eNOS protein (at serine 1177) attenuates the serine phosphorylation and prevents the activation of eNOS, Mimicking the phosphorylation of Ser1177 directly enhances enzyme activity and alters the sensitivity of the enzyme to Ca2+, rendering its activity maximal at sub-physiological concentrations of Ca2+. Thus, phosphorylation of eNOS by Akt represents a novel Ca2+-independent regulatory mechanism for activation of eNOS.