Alveolar epithelial ion and fluid transport -: Glucocorticoid-stimulated lung epithelial Na+ transport is associated with regulated ENaC and sgk1 expression
Alveolar epithelial ion and fluid transport -: Glucocorticoid-stimulated lung epithelial Na+ transport is associated with regulated ENaC and sgk1 expression
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DOI：
10.1152/ajplung.00085.2001
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发表时间：
2002-04-01
影响因子：
4.9
通讯作者：
Thomas, CP
中科院分区：
文献类型：
--
作者：
Itani, OA;Auerbach, SD;Thomas, CP
H441细胞是一种细支气管上皮细胞系，在渗透性支持物上形成糖皮质激素调节的阿米洛利敏感性Na+转运途径（R. Sayegh，S. D.奥尔巴赫，X.利河，巴西-地洛夫图斯河Husted，J. B. Stokes，和C. P.托马斯。J Biol Chem 274：12431- 12437，1999）。为了了解其分子基础，我们研究了糖皮质激素（GC）对上皮Na+通道（ENaC）-α，-β和-γ和sgk 1表达的影响，并确定了这些细胞中Na+通道的生物物理特性。GC刺激ENac-α、-β和-γ以及sgk 1 mRNA的表达，在1 h时观察到第一个效应。放线菌素D，但不是放线菌酮，这些影响被取消，表明ENaC和sgk 1 mRNA合成的直接刺激作用。GC对ENaC-α mRNA转录的影响伴随着ENaC-α蛋白水平的显著增加。GC还刺激肺泡II型细胞系A549细胞中ENaC-α、-β和-γ以及sgk 1 mRNA的表达。为了确定Na+通道的生物物理性质，从细胞附着的H441膜记录单通道电流。一个Na+-选择性通道与缓慢的动力学和斜率电导为10.8 pS的注意，属性类似于ENaC-α，β，和γ表达非洲爪蟾卵母细胞。这些实验表明，阿米洛利敏感的Na+转运是通过经典的ENaC通道介导的人肺上皮细胞和GC调节的Na+转运是伴随着每个组件亚基和sgk 1的转录增加。
H441 cells, a bronchiolar epithelial cell line, develop a glucocorticoid-regulated amiloride-sensitive Na+ transport pathway on permeable supports (R. Sayegh, S. D. Auerbach, X. Li, R. Loftus, R. Husted, J. B. Stokes, and C. P. Thomas. J Biol Chem 274: 12431- 12437, 1999). To understand its molecular basis, we examined the effect of glucocorticoids (GC) on epithelial Na+ channel (ENaC)-alpha, -beta, and -gamma and sgk1 expression and determined the biophysical properties of Na+ channels in these cells. GC stimulated the expression of ENac-alpha,-beta, and -gamma and sgk1 mRNA, with the first effect seen by 1 h. These effects were abolished by actinomycin D, but not by cycloheximide, indicating a direct stimulatory effect on ENaC and sgk1 mRNA synthesis. The GC effect on transcription of ENaC-alpha mRNA was accompanied by a significant increase in ENaC-alpha protein levels. GC also stimulated ENaC-alpha,-beta, and -gamma and sgk1 mRNA expression in A549 cells, an alveolar type II cell line. To determine the biophysical properties of the Na+ channel, single-channel currents were recorded from cell-attached H441 membranes. An Na+-selective channel with slow kinetics and a slope conductance of 10.8 pS was noted, properties similar to ENaC-alpha,-beta, and -gamma expressed in Xenopus laevis oocytes. These experiments indicate that amiloride-sensitive Na+ transport is mediated through classic ENaC channels in human lung epithelia and that GC-regulated Na+ transport is accompanied by increased transcription of each of the component subunits and sgk1.