Activation of the Epithelial Sodium Channel (ENaC) by the Alkaline Protease from Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen that significantly contributes to the mortality of patients with cystic fibrosis. Chronic infection by Pseudomonas induces sustained immune and inflammatory responses and damage to the airway. The ability of Pseudomonas to resist host defenses is a...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of biological chemistry 2012-09, Vol.287 (39), p.32556-32565
Main Authors: Butterworth, Michael B., Zhang, Liang, Heidrich, Elisa M., Myerburg, Michael M., Thibodeau, Patrick H.
Format: Article
Language:English
Subjects:
Animals
Bacterial Proteins - metabolism
Bronchi - metabolism
Bronchi - microbiology
Bronchi - pathology
Cell Line
Cell Polarity
Cystic Fibrosis
Cystic Fibrosis - metabolism
Cystic Fibrosis - microbiology
Cystic Fibrosis - pathology
ENaC
Endopeptidases - metabolism
Epithelial Cells - metabolism
Epithelial Cells - microbiology
Epithelial Cells - pathology
Epithelial Sodium Channels - metabolism
Humans
Mice
Molecular Bases of Disease
Physiology
Protease
Proteolysis
Pseudomonas aeruginosa
Pseudomonas aeruginosa - enzymology
Pseudomonas aeruginosa - pathogenicity
Pseudomonas Infections - metabolism
Pseudomonas Infections - microbiology
Pseudomonas Infections - pathology
Sodium Channels
Virulence Factors
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Pseudomonas aeruginosa is an opportunistic pathogen that significantly contributes to the mortality of patients with cystic fibrosis. Chronic infection by Pseudomonas induces sustained immune and inflammatory responses and damage to the airway. The ability of Pseudomonas to resist host defenses is aided, in part, by secreted proteases, which act as virulence factors in multiple modes of infection. Recent studies suggest that misregulation of protease activity in the cystic fibrosis lung may alter fluid secretion and pathogen clearance by proteolytic activation of the epithelial sodium channel (ENaC). To evaluate the possibility that proteolytic activation of ENaC may contribute to the virulence of Pseudomonas, primary human bronchial epithelial cells were exposed to P. aeruginosa and ENaC function was assessed by short circuit current measurements. Apical treatment with a strain known to express high levels of alkaline protease (AP) resulted in an increase in basal ENaC current and a loss of trypsin-inducible ENaC current, consistent with sustained activation of ENaC. To further characterize this AP-induced ENaC activation, AP was purified, and its folding, activity, and ability to activate ENaC were assessed. AP folding was efficient under pH and calcium conditions thought to exist in the airway surface liquid of normal and cystic fibrosis (CF) lungs. Short circuit measurements of ENaC in polarized monolayers indicated that AP activated ENaC in immortalized cell lines as well as post-transplant, primary human bronchial epithelial cells from both CF and non-CF patients. This activation was mapped to the γ-subunit of ENaC. Based on these data, patho-mechanisms associated with AP in the CF lung are proposed wherein secretion of AP leads to decreased airway surface liquid volume and a corresponding decrease in mucocilliary clearance of pulmonary pathogens. Background:Pseudomonas aeruginosa alkaline protease is a virulence factor that contributes to cystic fibrosis pathology. Results: The ENaC channel is activated by alkaline protease. Conclusion: Alkaline protease secretion may contribute to bacterial virulence by altering ENaC activity. Significance: The results provide insight into patho-mechanisms associated with alkaline protease secretion.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M112.369520