AMP-activated protein kinase regulates CO2-induced alveolar epithelial dysfunction in rats and human cells by promoting Na,K-ATPase endocytosis
István Vadász, … , Werner Seeger, Jacob I. Sznajder
István Vadász, … , Werner Seeger, Jacob I. Sznajder
Published January 10, 2008
Citation Information: J Clin Invest. 2008;118(2):752-762. https://doi.org/10.1172/JCI29723.
View: Text | PDF
Research Article Pulmonology

AMP-activated protein kinase regulates CO2-induced alveolar epithelial dysfunction in rats and human cells by promoting Na,K-ATPase endocytosis

Abstract

Hypercapnia (elevated CO2 levels) occurs as a consequence of poor alveolar ventilation and impairs alveolar fluid reabsorption (AFR) by promoting Na,K-ATPase endocytosis. We studied the mechanisms regulating CO2-induced Na,K-ATPase endocytosis in alveolar epithelial cells (AECs) and alveolar epithelial dysfunction in rats. Elevated CO2 levels caused a rapid activation of AMP-activated protein kinase (AMPK) in AECs, a key regulator of metabolic homeostasis. Activation of AMPK was mediated by a CO2-triggered increase in intracellular Ca2+ concentration and Ca2+/calmodulin-dependent kinase kinase-β (CaMKK-β). Chelating intracellular Ca2+ or abrogating CaMKK-β function by gene silencing or chemical inhibition prevented the CO2-induced AMPK activation in AECs. Activation of AMPK or overexpression of constitutively active AMPK was sufficient to activate PKC-ζ and promote Na,K-ATPase endocytosis. Inhibition or downregulation of AMPK via adenoviral delivery of dominant-negative AMPK-α1 prevented CO2-induced Na,K-ATPase endocytosis. The hypercapnia effects were independent of intracellular ROS. Exposure of rats to hypercapnia for up to 7 days caused a sustained decrease in AFR. Pretreatment with a β-adrenergic agonist, isoproterenol, or a cAMP analog ameliorated the hypercapnia-induced impairment of AFR. Accordingly, we provide evidence that elevated CO2 levels are sensed by AECs and that AMPK mediates CO2-induced Na,K-ATPase endocytosis and alveolar epithelial dysfunction, which can be prevented with β-adrenergic agonists and cAMP.

Authors

István Vadász, Laura A. Dada, Arturo Briva, Humberto E. Trejo, Lynn C. Welch, Jiwang Chen, Péter T. Tóth, Emilia Lecuona, Lee A. Witters, Paul T. Schumacker, Navdeep S. Chandel, Werner Seeger, Jacob I. Sznajder

×
Problems with a PDF?

This file is in Adobe Acrobat (PDF) format. If you have not installed and configured the Adobe Acrobat Reader on your system.

Having trouble reading a PDF?

PDFs are designed to be printed out and read, but if you prefer to read them online, you may find it easier if you increase the view size to 125%.

Having trouble saving a PDF?

Many versions of the free Acrobat Reader do not allow Save. You must instead save the PDF from the JCI Online page you downloaded it from. PC users: Right-click on the Download link and choose the option that says something like "Save Link As...". Mac users should hold the mouse button down on the link to get these same options.

Having trouble printing a PDF?

  1. Try printing one page at a time or to a newer printer.
  2. Try saving the file to disk before printing rather than opening it "on the fly." This requires that you configure your browser to "Save" rather than "Launch Application" for the file type "application/pdf", and can usually be done in the "Helper Applications" options.
  3. Make sure you are using the latest version of Adobe's Acrobat Reader.

Supplemental data - Download (250.88 KB)

Advertisement