Protein kinase A facilitates relaxation of mouse ileum via phosphorylation of neuronal nitric oxide synthase
Protein kinase A facilitates relaxation of mouse ileum via phosphorylation of neuronal nitric oxide synthase
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DOI：
10.1111/bph.15001
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发表时间：
2020-02-15
影响因子：
7.3
通讯作者：
Hurt, K. Joseph
中科院分区：
文献类型：
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作者：
Guerra, Damian D.;Bok, Rachael;Hurt, K. Joseph
背景和目的肠道神经递质一氧化氮（NO）通过松弛平滑肌来调节胃肠运动。药理学 cAMP 诱导也会放松胃肠道平滑肌，但尚不确定 cAMP 是增强还是抑制肠道 NO 信号传导。在其他器官系统中，cAMP 可以通过刺激蛋白激酶 A (PKA) 磷酸化神经元 NOS (nNOS) Serine-1412 (S1412) 来增加神经元 NO 的产生。我们假设cAMP 还通过PKA 在肠神经元中增加nNOS S1412 磷酸化，以增强小鼠回肠的氮能松弛。实验方法我们测量了悬浮在器官浴中的回肠环的收缩力和nNOS S1412 磷酸化。在存在或不存在 PKA、蛋白激酶 B (Akt) 和 NOS 抑制剂的情况下，我们使用毛喉素诱导野生型、nNOS(S1412A) 敲入和 nNOS α-无效回肠环的 cAMP 依赖性松弛。 主要结果毛喉素刺激小鼠回肠中 nNOS S1412 的磷酸化。 Forskolin 对 nNOS α-null 和 nNOS(S1412A) 回肠环的松弛程度低于野生型回肠环。 PKA 抑制可阻断毛喉素诱导的 nNOS 磷酸化并减弱野生型的松弛，但不会减弱 nNOS(S1412A) 回肠的松弛。 Akt 抑制不会改变毛喉素对 nNOS 的磷酸化，但会减弱野生型和 nNOS (S1412A) 的松弛。 L-NAME 抑制 NOS 消除了 PKA 和 Akt 抑制剂对松弛的影响。结论和意义 nNOS S1412 的 PKA 磷酸化增强了毛喉素诱导的硝能回肠松弛。因此，cAMP/PKA 和 NO 之间的关系在肠硝能神经元中具有协同作用。由于 NO 调节肠道运动，选择性调节肠神经元 cAMP 合成可能有助于治疗胃肠运动障碍。
Background and Purpose The enteric neurotransmitter nitric oxide (NO) regulates gastrointestinal motility by relaxing smooth muscle. Pharmacological cAMP induction also relaxes gastrointestinal smooth muscle, but it is uncertain whether cAMP augments or suppresses enteric NO signalling. In other organ systems, cAMP can increase neuronal NO production by stimulating protein kinase A (PKA) to phosphorylate neuronal NOS (nNOS) Serine-1412 (S1412). We hypothesized that cAMP also increases nNOS S1412 phosphorylation by PKA in enteric neurons to augment nitrergic relaxation of mouse ileum.Experimental Approach We measured contractile force and nNOS S1412 phosphorylation in ileal rings suspended in an organ bath. We used forskolin to induce cAMP-dependent relaxation of wild type, nNOS(S1412A) knock-in and nNOS alpha-null ileal rings in the presence or absence of PKA, protein kinase B (Akt) and NOS inhibitors.Key Results Forskolin stimulated phosphorylation of nNOS S1412 in mouse ileum. Forskolin relaxed nNOS alpha-null and nNOS(S1412A) ileal rings less than wild-type ileal rings. PKA inhibition blocked forskolin-induced nNOS phosphorylation and attenuated relaxation of wild type but not nNOS(S1412A) ileum. Akt inhibition did not alter nNOS phosphorylation with forskolin but did attenuate relaxation of wild type and nNOS(S1412A). NOS inhibition with L-NAME eliminated the effects of PKA and Akt inhibitors on relaxation.Conclusion and Implications PKA phosphorylation of nNOS S1412 augments forskolin-induced nitrergic ileal relaxation. The relationship between cAMP/PKA and NO is therefore synergistic in enteric nitrergic neurons. Because NO regulates gut motility, selective modulation of enteric neuronal cAMP synthesis may be useful for the treatment of gastrointestinal motility disorders.