Mechanisms of activity-dependent plasticity in cellular nitric oxide-cGMP signaling.
Mechanisms of activity-dependent plasticity in cellular nitric oxide-cGMP signaling.
复制标题
活性依赖性可塑性在细胞一氧化氮CGMP信号传导中的机制。
DOI：
10.1074/jbc.m109.030338
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发表时间：
2009-09-18
期刊：
影响因子：
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通讯作者：
Garthwaite J
中科院分区：
文献类型：
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作者：
Halvey EJ;Vernon J;Roy B;Garthwaite J
细胞对一氧化氮(NO)的反应是由过去的NO暴露史决定的。我们在体外用大鼠血小板探讨了这种可塑性背后的机制，特别是确定了NO受体的脱敏对cGMP形成的相对贡献，以及由cGMP激活并水解cGMP的磷酸二酯酶-5(PDE5)的相对贡献。每隔1分钟重复给予短暂的NO脉冲(50 nm峰)可导致相关cGMP反应的进行性丧失，这是受体脱敏和PDE5激活的共同结果，前者占主导地位。给予不同幅度的脉冲显示，无刺激和脱敏的受体具有相同的效力(EC50=10-20 nm)。PDE5的激活对NO高度敏感，单个脉冲在2 nm处达到峰值足以引起对随后接近最大的NO脉冲的50%反应损失。去除NO后，PDE的激活状态迅速消退，恢复的半衰期为25 S，而受体脱敏的恢复较慢，半衰期为16分钟。因此，在长时间(20分钟)暴露下，低至600 PM的NO浓度会引起显著的脱敏。结果表明，在NO-cGMP信号通路中，PDE5的激活和受体的脱敏作为可塑性的中介物，具有不同的短期和长期作用。一个明确描述NO浓度、cGMP合成、PDE5活化和cGMP积累之间复杂相互作用的动力学模型成功地模拟了当前和以前的数据。
Cellular responsiveness to nitric oxide (NO) is shaped by past history of NO exposure. The mechanisms behind this plasticity were explored using rat platelets in vitro, specifically to determine the relative contributions made by desensitization of NO receptors, which couple to cGMP formation, and by phosphodiesterase-5 (PDE5), which is activated by cGMP and also hydrolyzes it. Repeated delivery of brief NO pulses (50 nm peak) at 1-min intervals resulted in a progressive loss of the associated cGMP responses, which was the combined consequence of receptor desensitization and PDE5 activation, with the former dominating. Delivery of pulses of differing amplitude showed that NO stimulated and desensitized receptors with similar potency (EC50 = 10–20 nm). PDE5 activation was highly sensitive to NO, with a single pulse peaking at 2 nm being sufficient to evoke a 50% loss of response to a subsequent near-maximal NO pulse. However, the activated state of the PDE subsided quickly after removal of NO, the half-time for recovery being 25 s. In contrast, receptor desensitization reverted much more slowly, the half-time being 16 min. Accordingly, with long (20-min) exposures, NO concentrations as low as 600 pm provoked significant desensitization. The results indicate that PDE5 activation and receptor desensitization subserve distinct short term and longer term roles as mediators of plasticity in NO-cGMP signaling. A kinetic model explicitly describing the complex interplay between NO concentration, cGMP synthesis, PDE5 activation, and the resulting cGMP accumulation successfully simulated the present and previous data.