A fluid secretion pathway unmasked by acinar-specific Tmem16A gene ablation in the adult mouse salivary gland
A fluid secretion pathway unmasked by acinar-specific Tmem16A gene ablation in the adult mouse salivary gland
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DOI：
10.1073/pnas.1415739112
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发表时间：
2015-02-17
影响因子：
11.1
通讯作者：
Melvin, James E.
中科院分区：
文献类型：
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作者：
Catalan, Marcelo A.;Kondo, Yusuke;Melvin, James E.
顶端Ca 2+激活的Cl-通道（CaCC）的激活触发唾液的分泌。先前证明，在全身性Tmem 16 A（Tmem 16 A Cl-通道）缺失小鼠的腺泡细胞中不存在CaCC介导的Cl-电流和Cl-流出，但是在完全发育的腺体中没有评估流涎，因为Tmem 16 A缺失小鼠在出生后几天内死亡。为了测试Tmem 16 A在成年唾液腺中的作用，我们产生了腺泡细胞中缺乏Tmem 16 A的条件性敲除小鼠（Tmem 16 A（-/-））。在Tmem 16 A（-/-）小鼠中消除了Ca 2+依赖性流涎，表明Tmem 16 A对于Ca 2+介导的液体分泌是必需的。然而，Tmem 16 A（-/-）小鼠响应于β-肾上腺素能受体激动剂异丙肾上腺素（IPR）而分泌的唾液量与对照中所见的相当，表明Tmem 16 A对cAMP诱导的分泌没有显著贡献。此外，IPR刺激的分泌在缺乏Cftr（Cftr（Delta F508/Delta F508））或ClC-2（Clcn 2（-/-））Cl-通道的小鼠中不受影响。IPR刺激的液体分泌激活的时间过程与IPR诱导的细胞体积增加密切相关，表明腺泡肿胀可能激活体积敏感性Cl-通道。事实上，Cl-通道阻断剂消除了液体分泌，表明Cl（-）通道活性对IPR刺激的分泌至关重要。这些数据表明，β-肾上腺素能诱导的cAMP依赖性液体分泌涉及体积调节阴离子通道。总之，我们使用腺泡特异性Tmem 16 A（-/-）小鼠的结果将Tmem 16 A鉴定为成年小鼠唾液腺中毒蕈碱、Ca 2+依赖性液体分泌所必需的Cl-通道。
Activation of an apical Ca2+-activated Cl- channel (CaCC) triggers the secretion of saliva. It was previously demonstrated that CaCC-mediated Cl- current and Cl- efflux are absent in the acinar cells of systemic Tmem16A (Tmem16A Cl- channel) null mice, but salivation was not assessed in fully developed glands because Tmem16A null mice die within a few days after birth. To test the role of Tmem16A in adult salivary glands, we generated conditional knockout mice lacking Tmem16A in acinar cells (Tmem16A(-/-)). Ca2+-dependent salivation was abolished in Tmem16A(-/-) mice, demonstrating that Tmem16A is obligatory for Ca2+-mediated fluid secretion. However, the amount of saliva secreted by Tmem16A(-/-) mice in response to the beta-adrenergic receptor agonist isoproterenol (IPR) was comparable to that seen in controls, indicating that Tmem16A does not significantly contribute to cAMP-induced secretion. Furthermore, IPR-stimulated secretion was unaffected in mice lacking Cftr (Cftr(Delta F508/Delta F508)) or ClC-2 (Clcn2(-/-)) Cl- channels. The time course for activation of IPR-stimulated fluid secretion closely correlated with that of the IPR-induced cell volume increase, suggesting that acinar swelling may activate a volume-sensitive Cl- channel. Indeed, Cl- channel blockers abolished fluid secretion, indicating that Cl(-)channel activity is critical for IPR-stimulated secretion. These data suggest that beta-adrenergic-induced, cAMP-dependent fluid secretion involves a volume-regulated anion channel. In summary, our results using acinar-specific Tmem16A(-/-) mice identify Tmem16A as the Cl- channel essential for muscarinic, Ca2+-dependent fluid secretion in adult mouse salivary glands.