Myosin Va plays a key role in nitrergic neurotransmission by transporting nNOSα to enteric varicosity membrane
Myosin Va plays a key role in nitrergic neurotransmission by transporting nNOSα to enteric varicosity membrane
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DOI：
10.1152/ajpgi.00164.2011
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发表时间：
2011-09-01
影响因子：
4.5
通讯作者：
Goyal, Raj K.
中科院分区：
文献类型：
--
作者：
Chaudhury, Arun;He, Xue-Dao;Goyal, Raj K.
平滑肌神经肌肉接头处的氮能神经传递需要一氧化氮（NO）释放，其依赖于神经元NO合酶（nNOS）α向神经末梢膜的转运和对接。然而，在富含肌动蛋白的静脉曲张中nNOS α易位的机制尚不清楚。我们在这里报告，进行性运动蛋白肌球蛋白Va是必要的氮能神经传递。在野生型小鼠中，nNOS α染色的肠静脉曲张与肌球蛋白Va及其尾部组成轻链8（LC 8）共定位。原位邻位连接分析显示nNOS α、肌球蛋白Va和LC 8之间存在密切关联。nNOS α与静脉曲张膜相关。静脉曲张显示一氧化氮的生产与氯化钾刺激后。细胞内微电极研究表明，氮能IJP和平滑肌超极化反应，NO供体二乙烯三胺-NO（DNO）。相比之下，来自肌球蛋白Va缺陷DBA（对于稀释的、棕色的、非聚集的）小鼠的肠静脉曲张显示肌球蛋白Va几乎不存在，但nNOS α和LC 8正常。未检测到膜结合的nNOS α，静脉曲张显示NO产生减少。DBA小鼠的细胞内记录显示氮能IJPs减少，但对DNO的超极化反应正常。野生型对照组的氮能慢IJP为9.1 +/- 0.7 mV，DBA小鼠为3.4 +/- 0.3 mV（P < 0.0001）。肌球蛋白Va的缺乏导致氮能神经肌肉神经传递的损失，尽管正常存在的nNOS α静脉曲张。这些研究揭示了肌球蛋白Va在氮能神经传递中通过促进nNOS α转运到静脉曲张膜的至关重要性。
Nitrergic neurotransmission at the smooth muscle neuromuscular junctions requires nitric oxide (NO) release that is dependent on the transport and docking of neuronal NO synthase (nNOS) alpha to the membrane of nerve terminals. However, the mechanism of translocation of nNOS alpha in actin-rich varicosities is unknown. We report here that the processive motor protein myosin Va is necessary for nitrergic neurotransmission. In wild-type mice, nNOS alpha-stained enteric varicosities colocalized with myosin Va and its tail constituent light chain 8 (LC8). In situ proximity ligation assay showed close association among nNOS alpha, myosin Va, and LC8. nNOS alpha was associated with varicosity membrane. Varicosities showed nitric oxide production upon stimulation with KCl. Intracellular microelectrode studies showed nitrergic IJP and smooth muscle hyperpolarizing responses to NO donor diethylenetriamine-NO (DNO). In contrast, enteric varicosities from myosin Va-deficient DBA (for dilute, brown, non-agouti) mice showed near absence of myosin Va but normal nNOS alpha and LC8. Membrane-bound nNOS alpha was not detectable, and the varicosities showed reduced NO production. Intracellular recordings in DBA mice showed reduced nitrergic IJPs but normal hyperpolarizing response to DNO. The nitrergic slow IJP was 9.1 +/- 0.7 mV in the wild-type controls and 3.4 +/- 0.3 mV in the DBA mice (P < 0.0001). Deficiency of myosin Va resulted in loss of nitrergic neuromuscular neurotransmission despite normal presence of nNOS alpha in the varicosities. These studies reveal the critical importance of myosin Va in nitrergic neurotransmission by facilitating transport of nNOS alpha to the varicosity membrane.