CFTR regulation of intracellular pH and ceramides is required for lung endothelial cell apoptosis

Julie Noe, Daniela Petrusca, Natalia Rush, Ping Deng, Mary VanDemark, Evgeny Berdyshev, Yuan Gu, Patricia Smith, Kelly Schweitzer, Joseph Pilewsky, Viswanathan Natarajan, Zao Xu, Alexander G. Obukhov, Irina Petrache

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

The functional significance of the expression of cystic fibrosis transmembrane regulator (CFTR) on endothelial cells has not yet been elucidated. Since CFTR has been implicated in the regulation of intracellular sphingolipid levels, which are important regulators of endothelial cell apoptosis in response to various insults, we investigated the role of CFTR in the apoptotic responses of lung endothelial cells. CFTR was detected as a functional chloride channel in primary lung endothelial cells isolated from both pulmonary arteries (human or mouse) and bronchial arteries (sheep). Both specific CFTR inhibition with 2-(phenylamino) benzoic acid diphenylamine-2-carboxylic acid, 5-[(4-carboxyphenyl)methylene]-2-thioxo-3-[(3-trifluoromethyl) phenyl-4-thiazolidinone (CFTRinh-172), or 5-nitro-2-(3- phenylpropylamino)benzoic acid and CFTR knockdown significantly attenuated endothelial cell apoptosis induced by staurosporine or H2O 2. CFTRinh-172 treatment prevented the increases in the ceramide:sphingosine-1 phosphate ratio induced by H2O2 in lung endothelial cells. Replenishing endogenous ceramides via sphingomyelinase supplementation restored the susceptibility of CFTR-inhibited lung endothelial cells to H2O2-induced apoptosis. Similarly, the anti-apoptotic phenotype of CFTR-inhibited cells was reversed by lowering the intracellular pH, and was reproduced by alkalinization before H 2O2 challenge. TUNEL staining and active caspase-3 immunohistochemistry indicated that cellular apoptosis was decreased in lung explants from patients with cystic fibrosis compared with those with smoking-induced chronic obstructive lung disease, especially in the alveolar tissue and vascular endothelium. In conclusion, CFTR function is required for stress-induced apoptosis in lung endothelial cells by maintaining adequate intracellular acidification and ceramide activation. These results may have implications in the pathogenesis of cystic fibrosis, where aberrant endothelial cell death may dysregulate lung vascular homeostasis, contributingto abnormal angiogenesis andchronic inflammation.

Original languageEnglish (US)
Pages (from-to)314-323
Number of pages10
JournalAmerican journal of respiratory cell and molecular biology
Volume41
Issue number3
DOIs
StatePublished - Sep 1 2009

Keywords

  • Bronchial artery
  • Cell death
  • Cystic fibrosis
  • Oxidative stress
  • Pulmonary artery
  • Sphingolipids
  • Vascular

ASJC Scopus subject areas

  • Cell Biology
  • Pulmonary and Respiratory Medicine
  • Molecular Biology
  • Clinical Biochemistry

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