Critical role of CFTR-dependent lipid rafts in cigarette smoke-induced lung epithelial injury

Manish Bodas, Taehong Min, Neeraj Vij

Research output: Contribution to journalArticle

Abstract

Apoptosis of lung epithelial and endothelial cells by exposure to cigarette smoke (CS) severely damages the lung tissue, leading to the pathogenesis of emphysema, but the underlying mechanisms are poorly understood. We have recently established a direct correlation between decreased lipid raft CFTR expression and emphysema progression through increased ceramide accumulation. In the present work, we investigated the role of membrane CFTR in regulating apoptosis and autophagy responses to CS exposure. We report a constitutive and CS-induced increase in the number of TUNEL-positive apoptotic cells in Cftr-/- murine lungs compared with Cftr+/+ murine lungs that also correlated with a concurrent increase in the expression of ceramide, NF-κB, CD95/Fas, lipid raft proteins, and zonula occludens (ZO)-1/2 (P <0.001). We also verified that stable wild-type CFTR expression in CFBE41o- cells controls constitutively elevated caspase-3/7 activity (-1.6-fold, P <0.001). Our data suggest that membrane CFTR regulates ceramide-enriched lipid raft signaling platforms required for the induction of Fas-mediated apoptotic signaling. In addition, lack of membrane CFTR also modulates autophagy, as demonstrated by the significant increase in constitutive (P <0.001) and CSE-induced (P <0.005) perinuclear accumulation of green fluorescent protein-microtubule-associated protein 1 light chain-3 (LC3) in the absence of membrane CFTR (CFBE41o- cells). The significant constitutive and CS-induced increase (P <0.05) in p62 and LC3β expression in CFTR-deficient cells and mice corroborates these findings and suggest a defective autophagy response in the absence of membrane CFTR. Our data demonstrate the critical role of membrane-localized CFTR in regulating apoptotic and autophagic responses in CS-induced lung injury that may be involved in the pathogenesis of severe emphysema.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume300
Issue number6
DOIs
StatePublished - Jun 2011

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Lung Injury
Smoke
Tobacco Products
Lipids
Membranes
Ceramides
Autophagy
Emphysema
Lung
Zonula Occludens-2 Protein
Zonula Occludens-1 Protein
Apoptosis
Caspase 7
Light
Microtubule-Associated Proteins
In Situ Nick-End Labeling
Green Fluorescent Proteins
Caspase 3
Endothelial Cells
Epithelial Cells

Keywords

  • Apoptosis
  • Autophagy
  • Ceramide
  • Cystic fibrobsis transmembrane conductance regulator
  • Emphysema
  • Epithelium

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology
  • Physiology

Cite this

Critical role of CFTR-dependent lipid rafts in cigarette smoke-induced lung epithelial injury. / Bodas, Manish; Min, Taehong; Vij, Neeraj.

In: American Journal of Physiology - Lung Cellular and Molecular Physiology, Vol. 300, No. 6, 06.2011.

Research output: Contribution to journalArticle

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abstract = "Apoptosis of lung epithelial and endothelial cells by exposure to cigarette smoke (CS) severely damages the lung tissue, leading to the pathogenesis of emphysema, but the underlying mechanisms are poorly understood. We have recently established a direct correlation between decreased lipid raft CFTR expression and emphysema progression through increased ceramide accumulation. In the present work, we investigated the role of membrane CFTR in regulating apoptosis and autophagy responses to CS exposure. We report a constitutive and CS-induced increase in the number of TUNEL-positive apoptotic cells in Cftr-/- murine lungs compared with Cftr+/+ murine lungs that also correlated with a concurrent increase in the expression of ceramide, NF-κB, CD95/Fas, lipid raft proteins, and zonula occludens (ZO)-1/2 (P <0.001). We also verified that stable wild-type CFTR expression in CFBE41o- cells controls constitutively elevated caspase-3/7 activity (-1.6-fold, P <0.001). Our data suggest that membrane CFTR regulates ceramide-enriched lipid raft signaling platforms required for the induction of Fas-mediated apoptotic signaling. In addition, lack of membrane CFTR also modulates autophagy, as demonstrated by the significant increase in constitutive (P <0.001) and CSE-induced (P <0.005) perinuclear accumulation of green fluorescent protein-microtubule-associated protein 1 light chain-3 (LC3) in the absence of membrane CFTR (CFBE41o- cells). The significant constitutive and CS-induced increase (P <0.05) in p62 and LC3β expression in CFTR-deficient cells and mice corroborates these findings and suggest a defective autophagy response in the absence of membrane CFTR. Our data demonstrate the critical role of membrane-localized CFTR in regulating apoptotic and autophagic responses in CS-induced lung injury that may be involved in the pathogenesis of severe emphysema.",
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