cAMP has distinct acute and chronic effects on Aquaporin-5 in lung epithelial cells
cAMP has distinct acute and chronic effects on Aquaporin-5 in lung epithelial cells
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DOI：
10.1074/jbc.m411038200
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发表时间：
2005-02-04
影响因子：
4.8
通讯作者：
King, LS
中科院分区：
文献类型：
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作者：
Sidhaye, V;Hoffert, JD;King, LS
水通道蛋白-5（AQP 5）存在于各种分泌腺中的上皮细胞的顶膜上以及气道上皮、气道粘膜下腺和1型肺细胞的顶膜上，其中其可参与呼吸道水稳态。我们研究了cAMP对AQP 5分布和丰度的影响。当用cAMP或β-肾上腺素能激动剂特布他林处理表达AQP 5的小鼠肺上皮细胞时，观察到双相AQP 5反应。短期（分钟）暴露于cAMP产生的AQP 5的内化关闭的膜和蛋白质丰度的减少。这两种反应都被蛋白激酶A的抑制所阻断，并且丰度的降低被氯喹阻断，表明溶酶体介导的降解。持续的cAMP暴露（小时）产生的膜定位和丰度增加，这些影响也被蛋白激酶A抑制阻断。β-肾上腺素能激动剂特布他林在小鼠气管和肺中产生AQP 5丰度的变化，与我们在培养的上皮细胞中的发现一致。纯化的AQP 5蛋白被蛋白激酶A磷酸化，但不被蛋白激酶C或酪蛋白激酶II磷酸化，并且在长期（但不是短期）暴露于cAMP后培养的细胞中水通道蛋白5被磷酸化。这些研究表明，cAMP和β-肾上腺素能激动剂对AQP 5分布和丰度产生不同的短期和长期影响，这可能有助于调节肺水稳态。
Aquaporin-5 (AQP5) is present on the apical membrane of epithelial cells in various secretory glands as well as on the apical membrane of the airway epithelium, airway submucosal glands, and type 1 pneumocytes, where it can participate in respiratory tract water homeostasis. We examined the effects of cAMP on AQP5 distribution and abundance. When AQP5-expressing mouse lung epithelial cells were treated with cAMP or the beta-adrenergic agonist terbutaline, a biphasic AQP5 response was observed. Short term (minutes) exposure to cAMP produced internalization of AQP5 off of the membrane and a decrease in protein abundance. Both of these responses were blocked by inhibition of protein kinase A and the decrease in abundance was blocked by chloroquine, indicating lysosome-mediated degradation. Sustained cAMP exposure (hours) produced an increase in membrane localization and increased abundance; these effects were also blocked by protein kinase A inhibition. The beta-adrenergic agonist terbutaline produced changes in AQP5 abundance in mouse trachea and lung, consistent with our findings in cultured epithelial cells. Purified AQP5 protein was phosphorylated by protein kinase A but not protein kinase C or casein kinase II, and aquaporin-5 was phosphorylated in cultured cells after long term (but not short term) exposure to cAMP. These studies indicate that cAMP and beta-adrenergic agonists produce distinct short and long term effects on AQP5 distribution and abundance that may contribute to regulation of lung water homeostasis.