cAMP-stimulated Na+ transport in H441 distal lung epithelial cells: role of PKA, phosphatidylinositol 3-kinase, and sgk1.
cAMP-stimulated Na+ transport in H441 distal lung epithelial cells: role of PKA, phosphatidylinositol 3-kinase, and sgk1.
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DOI：
10.1152/ajplung.00340.2003
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发表时间：
2004-10
期刊：
影响因子：
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通讯作者：
Christie P. Thomas;Jason R. Campbell;P. J. Wright;R. Husted
中科院分区：
文献类型：
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作者：
Christie P. Thomas;Jason R. Campbell;P. J. Wright;R. Husted
H441细胞是一种细支气管上皮细胞系，在可渗透载体(安泰OA、奥尔巴赫SD、赫斯特德RF、Volk KA、阿格洛夫S、克奈珀MA、斯托克斯JB、托马斯CP)上形成cAMP调节的苯扎胺敏感的Na+转运途径。Am J Physiol肺细胞分子Physiol 282：L631-L641,2002)。为了了解刺激Na+转运的分子基础，我们描述了特定的细胞内途径的作用，并检测了cAMP对α-上皮Na+通道(ENaC)和SGK1表达的影响。CAMP对Na+转运的持续效应可被磷脂酰肌醇3-激酶抑制剂LY-294002、蛋白激酶A抑制剂H89或p38 MAP激酶抑制剂SB-202190所阻断。CAMP的持续作用与α-ENaC的mRNA和蛋白的增加有关，但与β-ENaC和SGK1的增加无关。CAMP对Na+转运的早期作用是布雷菲尔丁敏感的，并通过PKA介导。这些结果与cAMP的早期作用是增加Na+通道向心尖细胞表面的转运而持续作用需要合成α-ENaC的模型是一致的。
H441 cells, a bronchiolar epithelial cell line, develop a cAMP-regulated benzamil-sensitive Na+ transport pathway on permeable supports (Itani OA, Auerbach SD, Husted RF, Volk KA, Ageloff S, Knepper MA, Stokes JB, Thomas CP. Am J Physiol Lung Cell Mol Physiol 282: L631-L641, 2002). To understand the molecular basis for the stimulation of Na+ transport, we delineated the role of specific intracellular pathways and examined the effect of cAMP on alphabetagamma-epithelial Na+ channel (ENaC) and sgk1 expression. Na+ transport increases within 5 min of cAMP stimulation and is sustained for >24 h. The sustained effect of cAMP on Na+ transport is abolished by LY-294002, an inhibitor of phosphatidylinositol 3-kinase, by H89, an inhibitor of PKA, or by SB-202190, an inhibitor of p38 MAP kinase. The sustained effect of cAMP was associated with increases in alpha-ENaC mRNA and protein but without a detectable increase in betagamma-ENaC and sgk1. The early effect of cAMP on Na+ transport is brefeldin sensitive and is mediated via PKA. These results are consistent with a model where the early effect of cAMP is to increase trafficking of Na+ channels to the apical cell surface whereas the sustained effect requires the synthesis of alpha-ENaC.