cAMP has distinct acute and chronic effects on aquaporin-5 in lung epithelial cells

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84 Scopus citations


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 β-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 β-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 β-adrenergic agonists produce distinct short and long term effects on AQP5 distribution and abundance that may contribute to regulation of lung water homeostasis.

Original languageEnglish (US)
Pages (from-to)3590-3596
Number of pages7
JournalJournal of Biological Chemistry
Issue number5
StatePublished - Feb 4 2005

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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