Schreiber Rainer, Faria Diana, Skryabin Boris V, Wanitchakool Podchanart, Rock Jason R, Kunzelmann Karl
Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053, Regensburg, Germany.
Pflugers Arch. 2015 Jun;467(6):1203-13. doi: 10.1007/s00424-014-1559-2. Epub 2014 Jul 1.
Intestinal epithelial electrolyte secretion is activated by increase in intracellular cAMP or Ca(2+) and opening of apical Cl(-) channels. In infants and young animals, but not in adults, Ca(2+)-activated chloride channels may cause secretory diarrhea during rotavirus infection. While detailed knowledge exists concerning the contribution of cAMP-activated cystic fibrosis transmembrane conductance regulator (CFTR) channels, analysis of the role of Ca(2+)-dependent Cl(-) channels became possible through identification of the anoctamin (TMEM16) family of proteins. We demonstrate expression of several anoctamin paralogues in mouse small and large intestines. Using intestinal-specific mouse knockout models for anoctamin 1 (Ano1) and anoctamin 10 (Ano10) and a conventional knockout model for anoctamin 6 (Ano6), we demonstrate the role of anoctamins for Ca(2+)-dependent Cl(-) secretion induced by the muscarinic agonist carbachol (CCH). Ano1 is preferentially expressed in the ileum and large intestine, where it supports Ca(2+)-activated Cl(-) secretion. In contrast, Ano10 is essential for Ca(2+)-dependent Cl(-) secretion in jejunum, where expression of Ano1 was not detected. Although broadly expressed, Ano6 has no role in intestinal cholinergic Cl(-) secretion. Ano1 is located in a basolateral compartment/membrane rather than in the apical membrane, where it supports CCH-induced Ca(2+) increase, while the essential and possibly only apical Cl(-) channel is CFTR. These results define a new role of Ano1 for intestinal Ca(2+)-dependent Cl(-) secretion and demonstrate for the first time a contribution of Ano10 to intestinal transport.
肠道上皮电解质分泌通过细胞内cAMP或Ca(2+)增加以及顶端Cl(-)通道开放而被激活。在婴儿和幼小动物中，而非成年动物中，Ca(2+)激活的氯离子通道可能在轮状病毒感染期间引起分泌性腹泻。虽然关于cAMP激活的囊性纤维化跨膜传导调节因子（CFTR）通道的作用已有详细了解，但通过鉴定anoctamin（TMEM16）蛋白家族，对Ca(2+)依赖性Cl(-)通道的作用分析成为可能。我们证明了几种anoctamin旁系同源物在小鼠小肠和大肠中的表达。使用anoctamin 1（Ano1）和anoctamin 10（Ano10）的肠道特异性小鼠敲除模型以及anoctamin 6（Ano6）的传统敲除模型，我们证明了anoctamins对毒蕈碱激动剂卡巴胆碱（CCH）诱导的Ca(2+)依赖性Cl(-)分泌的作用。Ano1优先在回肠和大肠中表达，在那里它支持Ca(2+)激活的Cl(-)分泌。相比之下，Ano10对空肠中Ca(2+)依赖性Cl(-)分泌至关重要，在空肠中未检测到Ano1的表达。虽然广泛表达，但Ano6在肠道胆碱能Cl(-)分泌中不起作用。Ano1位于基底外侧区室/膜而非顶端膜，在那里它支持CCH诱导的Ca(2+)增加，而必需且可能唯一的顶端Cl(-)通道是CFTR。这些结果确定了Ano1在肠道Ca(2+)依赖性Cl(-)分泌中的新作用，并首次证明了Ano10对肠道转运的贡献。
