NADPH-oxidase and a hydrogen peroxide-sensitive K+ channel may function as an oxygen sensor complex in airway chemoreceptors and small cell lung carcinoma cell lines.
NADPH-oxidase and a hydrogen peroxide-sensitive K+ channel may function as an oxygen sensor complex in airway chemoreceptors and small cell lung carcinoma cell lines.
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DOI：
10.1073/pnas.93.23.13182
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发表时间：
1996-11
影响因子：
11.1
通讯作者：
Dashou Wang;C. Youngson;V. Wong;H. Yeger;M. Dinauer;E. V. Miera;B. Rudy;E. Cutz
中科院分区：
文献类型：
--
作者：
Dashou Wang;C. Youngson;V. Wong;H. Yeger;M. Dinauer;E. V. Miera;B. Rudy;E. Cutz
肺神经上皮小体（NEB）广泛分布于人和动物肺的气道粘膜。根据观察到NEB细胞具有候选氧传感器酶复合物（NADPH氧化酶）和氧敏感的K+电流，有人认为NEB可能具有气道化学受体的功能。在这里，我们报道了过氧化氢敏感电压门控钾通道亚基（KH2O2） KV3.3a和NADPH氧化酶膜组分（gp91phox和p22phox）的mrna在胎兔和新生儿人肺的NEB细胞中共表达。使用微荧光法和二氢膦胺123作为探针来评估H2O2的产生，NEB细胞在基础条件下表现出氧化酶活性。0.1 μ m的佛波埃斯特对NEB细胞的氧化酶有明显的刺激作用，5 μ m的二苯硫肼对NEB细胞的氧化酶有明显的抑制作用。利用全细胞电压钳的研究表明，培养的胎兔NEB细胞的K+电流表现出与爪蟾卵母细胞模型中表达的KV3.3a转录本相似的失活特性。在常氧条件下，将NEB细胞暴露于过氧化氢（H2O2，氧化酶的非降解副产物）中，导致向外K+电流增加，表明H2O2可能是调节o2敏感的K+通道的发射器。在小细胞肺癌细胞系中发现了NADPH氧化酶膜细胞色素b的mRNA或相应的蛋白产物，以及编码KV3.3a的mRNA。本研究提供了强有力的证据，证明氧化酶-O2敏感钾通道分子复合物在NEB细胞中作为O2传感器，在气道和NEB相关肿瘤中发挥化学受体的作用。这种复合体可能代表了其他细胞和生命形式的膜结合o2信号传导机制的进化保守的生化联系。
Pulmonary neuroepithelial bodies (NEB) are widely distributed throughout the airway mucosa of human and animal lungs. Based on the observation that NEB cells have a candidate oxygen sensor enzyme complex (NADPH oxidase) and an oxygen-sensitive K+ current, it has been suggested that NEB may function as airway chemoreceptors. Here we report that mRNAs for both the hydrogen peroxide sensitive voltage gated potassium channel subunit (KH2O2) KV3.3a and membrane components of NADPH oxidase (gp91phox and p22phox) are coexpressed in the NEB cells of fetal rabbit and neonatal human lungs. Using a microfluorometry and dihydrorhodamine 123 as a probe to assess H2O2 generation, NEB cells exhibited oxidase activity under basal conditions. The oxidase in NEB cells was significantly stimulated by exposure to phorbol esther (0.1 microM) and inhibited by diphenyliodonium (5 microM). Studies using whole-cell voltage clamp showed that the K+ current of cultured fetal rabbit NEB cells exhibited inactivating properties similar to KV3.3a transcripts expressed in Xenopus oocyte model. Exposure of NEB cells to hydrogen peroxide (H2O2, the dismuted by-product of the oxidase) under normoxia resulted in an increase of the outward K+ current indicating that H2O2 could be the transmitter modulating the O2-sensitive K+ channel. Expressed mRNAs or corresponding protein products for the NADPH oxidase membrane cytochrome b as well as mRNA encoding KV3.3a were identified in small cell lung carcinoma cell lines. The studies presented here provide strong evidence for an oxidase-O2 sensitive potassium channel molecular complex operating as an O2 sensor in NEB cells, which function as chemoreceptors in airways and in NEB related tumors. Such a complex may represent an evolutionary conserved biochemical link for a membrane bound O2-signaling mechanism proposed for other cells and life forms.