The transmembrane protein 16A Ca(2+)-activated Cl- channel in airway smooth muscle contributes to airway hyperresponsiveness.
The transmembrane protein 16A Ca(2+)-activated Cl- channel in airway smooth muscle contributes to airway hyperresponsiveness.
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DOI：
10.1164/rccm.201207-1303oc
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发表时间：
2013-02
影响因子：
24.7
通讯作者：
Cheng-Hai Zhang;Yinchuan Li;Wei Zhao;Lawrence M. Lifshitz;Hequan Li;B. Harfe;Min-Sheng Zhu;R. Zhuge
中科院分区：
文献类型：
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作者：
Cheng-Hai Zhang;Yinchuan Li;Wei Zhao;Lawrence M. Lifshitz;Hequan Li;B. Harfe;Min-Sheng Zhu;R. Zhuge
哮喘是一种以气道高反应性（AHR）为特征的慢性炎症性疾病。Ca（2+）激活的Cl（-）[Cl（（Ca））]通道被推测参与AHR，但它们的分子性质和它们在其中起作用以介导这种反应的细胞类型仍然未知。跨膜蛋白16 A（TMEM 16 A）和TMEM 16 B是Cl（（Ca））通道，气道平滑肌（ASM）中Cl（（Ca））通道的激活有助于激动剂诱导的气道收缩。我们假设Tmem 16 a和/或Tmem 16 b编码ASM中的Cl（（Ca））通道并介导AHR。方法：在卵白蛋白致敏的慢性哮喘小鼠模型中，我们评估了TMEM 16家族的表达，以及尼氟灭酸和苯溴马隆对AHR和气道收缩的影响。我们还从ASM中克隆了TMEM 16 A，并检测了它在HEK 293细胞中产生的Cl（-）电流。我们进一步研究了TMEM 16 A缺失对小鼠ASM细胞中Ca（2+）激动剂诱导的细胞缩短和由Ca（2+）火花（由于兰尼碱受体的开放而引起的局部、短暂的Ca（2+）瞬变）激活的Cl（（Ca））电流的影响。测量和主要结果TMEM 16 A，而不是TMEM 16 B，在ASM细胞中表达，并且其在这些细胞中的表达在卵清蛋白致敏的小鼠中上调。硝氟灭酸和苯溴马隆预防卵白蛋白致敏小鼠乙酰甲胆碱诱发的AHR和收缩。TMEM 16 A产生Cl（（Ca））电流，其动力学类似于天然Cl（（Ca））电流。TMEM 16 A缺失使得Ca（2+）火花不能激活Cl（（Ca））电流，并减弱咖啡因和乙酰甲胆碱诱导的细胞缩短。结论Tmem 16 a编码平滑肌Cl（（Ca））通道，参与Ca（2+）激动剂引起的平滑肌收缩。此外，在卵清蛋白致敏的慢性哮喘小鼠模型中，TMEM 16 A的上调及其增强的活化有助于AHR。TMEM 16 A可能是哮喘的潜在治疗靶点。
RATIONALE Asthma is a chronic inflammatory disorder with a characteristic of airway hyperresponsiveness (AHR). Ca(2+)-activated Cl(-) [Cl((Ca))] channels are inferred to be involved in AHR, yet their molecular nature and the cell type they act within to mediate this response remain unknown. OBJECTIVES Transmembrane protein 16A (TMEM16A) and TMEM16B are Cl((Ca)) channels, and activation of Cl((Ca)) channels in airway smooth muscle (ASM) contributes to agonist-induced airway contraction. We hypothesized that Tmem16a and/or Tmem16b encode Cl((Ca)) channels in ASM and mediate AHR. METHODS We assessed the expression of the TMEM16 family, and the effects of niflumic acid and benzbromarone on AHR and airway contraction, in an ovalbumin-sensitized mouse model of chronic asthma. We also cloned TMEM16A from ASM and examined the Cl(-) currents it produced in HEK293 cells. We further studied the impacts of TMEM16A deletion on Ca(2+) agonist-induced cell shortening, and on Cl((Ca)) currents activated by Ca(2+) sparks (localized, short-lived Ca(2+) transients due to the opening of ryanodine receptors) in mouse ASM cells. MEASUREMENTS AND MAIN RESULTS TMEM16A, but not TMEM16B, is expressed in ASM cells and its expression in these cells is up-regulated in ovalbumin-sensitized mice. Niflumic acid and benzbromarone prevent AHR and contraction evoked by methacholine in ovalbumin-sensitized mice. TMEM16A produces Cl((Ca)) currents with kinetics similar to native Cl((Ca)) currents. TMEM16A deletion renders Ca(2+) sparks unable to activate Cl((Ca)) currents, and weakens caffeine- and methacholine-induced cell shortening. CONCLUSIONS Tmem16a encodes Cl((Ca)) channels in ASM and contributes to Ca(2+) agonist-induced contraction. In addition, up-regulation of TMEM16A and its augmented activation contribute to AHR in an ovalbumin-sensitized mouse model of chronic asthma. TMEM16A may represent a potential therapeutic target for asthma.