Acid inhibits TRPV4-mediated Ca^2+influx in mouse esophageal epithelial cells
Acid inhibits TRPV4-mediated Ca^2+influx in mouse esophageal epithelial cells
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酸抑制小鼠食管上皮细胞中 TRPV4 介导的 Ca^2 内流
DOI：
10.1111/j.1365-2982.2011.01767.x
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
Joh T
中科院分区：
文献类型：
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作者：
Shikano M;Ueda T;Kamiya T;Ishida Y;Yamada T;Mizushima T;Shimura T;Mizoshita T;Tanida S;Kataoka H;Shimada S;Ugawa S;Joh T
瞬时受体电位香草样蛋白4 （TRPV4）是一种热敏拉伸激活的阳离子通道，在皮肤分层鳞状上皮中表达，有助于获得屏障功能。同样，功能性TRPV4可能位于食管分层鳞状上皮内膜，参与胃食管反流病（GERD）的发病机制。我们研究了TRPV4在小鼠食管上皮中的表达。方法采用逆转录聚合酶链反应（RT - PCR）、原位杂交和免疫组织化学检测strpv4 mRNA和蛋白水平的表达。应用钙显像技术和ATP检测评价新分离食管上皮细胞中TRPV4的功能。关键结果TRPV4的转录本和编码蛋白共定位于食管上皮的基底层和中间层。TRPV4的选择性激动剂4α - phorbol 12,13 - didecanoate （4α - PDD）和低渗透压溶液（160 mOsm）均可提高部分分离细胞（70%）的细胞内钙浓度（[Ca2+]i）。这些[Ca2+]的增加被TRPV4通道拮抗剂钌红（RuR）有效抑制，并被细胞外质子（pH 5.0）抑制。最后，应用4α - PDD诱导原代食管上皮细胞释放ATP。结论与推论酸敏感TRPV4通道主要表达于食管基底和中间层上皮细胞。表达TRPV4的细胞直接暴露于胃酸中，如在反流胃食管反流中发生的情况，可能会影响其细胞功能，可能会加重疾病状态。
BackgroundThe transient receptor potential vanilloid 4 (TRPV4), a thermo‐sensitive stretch‐activated cation channel, is expressed in the skin stratified squamous epithelium, contributing to the acquisition of barrier function. Similarly, functional TRPV4 may be located in the stratified squamous epithelial lining of the esophagus, being involved in the pathogenesis of gastroesophageal reflux disease (GERD). Here we investigated the expression of TRPV4 in the mouse esophageal epithelium.MethodsTRPV4 expression at the mRNA and protein levels was examined by reverse transcription‐polymerase chain reaction (RT‐PCR), in situ hybridization, and immunohistochemistry. A calcium imaging technique and ATP assay were used to evaluate the functionality of TRPV4 in freshly isolated esophageal epithelial cells.Key ResultsTranscripts and proteins encoding TRPV4 were colocalized in the basal and intermediate layers of the esophageal epithelium. Both 4α‐phorbol 12,13‐ didecanoate (4α‐PDD), a selective agonist for TRPV4, and hypo‐osmolar solution (160 mOsm) elevated the intracellular calcium concentration ([Ca2+]i) in a subset of the isolated cells (70%). These [Ca2+]iincreases were potently inhibited by ruthenium red (RuR), a TRPV4 channel antagonist, and were suppressed by extracellular protons (pH 5.0). Finally, application of 4α‐PDD evoked ATP release in primary esophageal epithelial cells.Conclusions & InferencesAcid‐sensitive TRPV4 channels were mainly expressed in the esophageal epithelial cells of the basal and intermediate layers. Direct exposure of TRPV4‐expressing cells to gastric acid, as would occur in cases of GERD, could influence their cellular functions, possibly aggravating the disease state.