Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Am J Physiol Cell Physiol. 2013 Apr 1;304(7):C673-84. doi: 10.1152/ajpcell.00196.2012. Epub 2013 Jan 30.
Purinergic agonists have been considered for the treatment of respiratory epithelia in cystic fibrosis (CF) patients. The pancreas, one of the most seriously affected organs in CF, expresses various purinergic receptors. Studies on the rodent pancreas show that purinergic signaling regulates pancreatic secretion. In the present study we aim to identify Cl(-) and K(+) channels in human pancreatic ducts and their regulation by purinergic receptors. Human pancreatic duct epithelia formed by Capan-1 or CFPAC-1 cells were studied in open-circuit Ussing chambers. In Capan-1 cells, ATP/UTP effects were dependent on intracellular Ca(2+). Apically applied ATP/UTP stimulated CF transmembrane conductance regulator (CFTR) and Ca(2+)-activated Cl(-) (CaCC) channels, which were inhibited by CFTRinh-172 and niflumic acid, respectively. The basolaterally applied ATP stimulated CFTR. In CFPAC-1 cells, which have mutated CFTR, basolateral ATP and UTP had negligible effects. In addition to Cl(-) transport in Capan-1 cells, the effects of 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DC-EBIO) and clotrimazole indicated functional expression of the intermediate conductance K(+) channels (IK, KCa3.1). The apical effects of ATP/UTP were greatly potentiated by the IK channel opener DC-EBIO. Determination of RNA and protein levels revealed that Capan-1 cells have high expression of TMEM16A (ANO1), a likely CaCC candidate. We conclude that in human pancreatic duct cells ATP/UTP regulates via purinergic receptors both Cl(-) channels (TMEM16A/ANO1 and CFTR) and K(+) channels (IK). The K(+) channels provide the driving force for Cl(-)-channel-dependent secretion, and luminal ATP provided locally or secreted from acini may potentiate secretory processes. Future strategies in augmenting pancreatic duct function should consider sidedness of purinergic signaling and the essential role of K(+) channels.
嘌呤能激动剂已被认为可用于治疗囊性纤维化 (CF) 患者的呼吸道上皮细胞。胰腺是 CF 中受影响最严重的器官之一，它表达各种嘌呤能受体。关于啮齿动物胰腺的研究表明，嘌呤能信号调节胰腺分泌。在本研究中，我们旨在鉴定人胰腺导管中的 Cl(-) 和 K(+) 通道及其受嘌呤能受体的调节。用人胰腺导管上皮细胞 Capan-1 或 CFPAC-1 细胞在开放电路 Ussing 室中进行研究。在 Capan-1 细胞中，ATP/UTP 的作用依赖于细胞内 Ca(2+)。ATP/UTP 可刺激顶端的 CF 跨膜电导调节剂 (CFTR) 和 Ca(2+)-激活的 Cl(-) (CaCC) 通道，这两种通道分别被 CFTRinh-172 和尼氟灭酸抑制。基底外侧应用的 ATP 刺激 CFTR。在具有突变 CFTR 的 CFPAC-1 细胞中，基底外侧 ATP 和 UTP 几乎没有作用。除了 Capan-1 细胞中的 Cl(-) 转运外，5,6-二氯-1-乙基-1,3-二氢-2H-苯并咪唑-2-酮 (DC-EBIO) 和克霉唑的作用表明中间电导 K(+) 通道 (IK，KCa3.1) 的功能表达。ATP/UTP 的顶端作用被 IK 通道开放剂 DC-EBIO 大大增强。RNA 和蛋白质水平的测定表明 Capan-1 细胞高表达 TMEM16A (ANO1)，这可能是 CaCC 的候选者。我们得出结论，在人胰腺导管细胞中，ATP/UTP 通过嘌呤能受体调节 Cl(-) 通道 (TMEM16A/ANO1 和 CFTR) 和 K(+) 通道 (IK)。K(+) 通道为 Cl(-) 通道依赖性分泌提供驱动力，而腔内 ATP 可能局部提供或从腺泡分泌，从而增强分泌过程。增强胰腺导管功能的未来策略应考虑嘌呤能信号的方向性和 K(+) 通道的重要作用。
