Loss of hyperpolarization-activated Cl- current in salivary acinar cells from Clcn2 knockout mice
Loss of hyperpolarization-activated Cl- current in salivary acinar cells from Clcn2 knockout mice
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DOI：
10.1074/jbc.m202900200
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发表时间：
2002-06-28
影响因子：
4.8
通讯作者：
Melvin, JE
中科院分区：
文献类型：
--
作者：
Nehrke, K;Arreola, J;Melvin, JE
ClC-2定位于分泌上皮细胞的顶端膜，在那里它被假设在液体分泌中起作用。虽然ClC-2显然是在几个组织中的内向整流阴离子通道，超极化激活的Cl-电流在其他器官，包括唾液腺的分子身份，目前是未知的。以确定超极化激活的性质。Cl-电流和检查ClC-2在唾液腺功能中的作用，产生含有Clcn 2基因的靶向破坏的小鼠系。由此产生的纯合子Clcn 2（-/-）小鼠在腮腺腺泡细胞中缺乏可检测的超极化激活的氯电流，并且如前所述，显示出视网膜和睾丸的出生后变性。在这些细胞中的体积和钙激活的氯电流的幅度和生物物理特性不受CLC-2的情况下。虽然ClC-2似乎有助于某些细胞类型中的液体分泌，但在用匹鲁卡品（一种胆碱能激动剂）进行体内刺激后，Clcn 2（-/-）小鼠的初始和持续唾液流速均正常。此外，成熟分泌物的电解质和蛋白质含量正常。由于ClC-2被假定有助于细胞体积控制，我们还检查了细胞肿胀后的调节体积减少。然而，来自Clcn 2（-/-）小鼠的腮腺腺泡细胞以与野生型同窝小鼠相似的效率恢复体积。这些数据表明，ClC-2是超极化激活的Cl-通道在唾液腺泡细胞，但不是必不可少的刺激分泌唾液或腺泡细胞体积调节过程中的最大氯流量。
ClC-2 is localized to the apical membranes of secretory epithelia where it has been hypothesized to play a role in fluid secretion. Although ClC-2 is clearly the inwardly rectifying anion channel in several tissues, the molecular identity of the hyperpolarization-activated Cl- current in other organs, including the salivary gland, is currently unknown. To determine the nature of the hyperpolarization-activated. Cl- current and to examine the role of ClC-2 in salivary gland function, a mouse line containing a targeted disruption of the Clcn2 gene was generated. The resulting homozygous Clcn2(-/-) mice lacked detectable hyperpolarization-activated chloride currents in parotid acinar cells and, as described previously, displayed postnatal degeneration of the retina and testis. The magnitude and biophysical characteristics of the volume- and calcium-activated chloride currents in these cells were unaffected by the absence of ClC-2. Although ClC-2 appears to contribute to fluid secretion in some cell types, both the initial and sustained salivary flow rates were normal in Clcn2(-/-) mice following in vivo stimulation with pilocarpine, a cholinergic agonist. In addition, the electrolytes and protein contents of the mature secretions were normal. Because ClC-2 has been postulated to contribute to cell volume control, we also examined regulatory volume decrease following cell swelling. However, parotid acinar cells from Clcn2(-/-) mice recovered volume with similar efficiency to wild-type littermates. These data demonstrate that ClC-2 is the hyperpolarization-activated Cl- channel in salivary acinar cells but is not essential for maximum chloride flux during stimulated secretion of saliva or acinar cell volume regulation.