Phosphorylation-dependent modulation of CFTR macromolecular signalling complex activity by cigarette smoke condensate in airway epithelia

Sci Rep. 2019 Sep 3;9(1):12706. doi: 10.1038/s41598-019-48971-y.

Abstract

Genetic and acquired loss-of-function defect of the cystic fibrosis transmembrane conductance regulator (CFTR) compromise airway surface liquid homeostasis and mucociliary clearance (MCC), culminating in recurrent lung inflammation/infection. While chronic cigarette smoke (CS), CS extract (CSE; water-soluble compounds) and CS condensate (CSC; particulate, organic fraction) exposure inhibit CFTR activity at transcriptional, biochemical, and functional levels, the acute impact of CSC remains incompletely understood. We report that CSC transiently activates CFTR chloride secretion in airway epithelia. The comparable CFTR phospho-occupancy after CSC- and forskolin-exposure, determined by affinity-enriched tandem mass spectrometry and pharmacology, suggest that localised cAMP-dependent protein kinase (PKA) stimulation by CSC causes the channel opening. Due to the inhibition of the MRP4/ABCC4, a cAMP-exporter confined to the CFTR macromolecular signalling-complex, PKA activation is accomplished by the subcompartmentalised elevation of cytosolic cAMP. In line, MRP4 inhibition results in CFTR activation and phospho-occupancy similar to that by forskolin. In contrast, acute CSC exposure reversibly inhibits the phosphorylated CFTR both in vivo and in phospholipid bilayers, without altering its cell surface density and phospho-occupancy. We propose that components of CSC elicit both a transient protective CFTR activation, as well as subsequent channel block in airway epithelia, contributing to the subacute MCC defect in acquired CF lung diseases.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cigarette Smoking / metabolism*
  • Cigarette Smoking / pathology
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism*
  • Humans
  • Multidrug Resistance-Associated Proteins / metabolism
  • Phosphorylation
  • Respiratory Mucosa / metabolism*
  • Respiratory Mucosa / pathology
  • Second Messenger Systems*
  • Smoke

Substances

  • ABCC4 protein, human
  • CFTR protein, human
  • Multidrug Resistance-Associated Proteins
  • Smoke
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases