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Hyperoxia-induced LC3B interacts with the Fas apoptotic pathway in epithelial cell death.

Authors
  • Tanaka, Akihiko
  • Jin, Yang
  • Lee, Seon-Jin
  • Zhang, Meng
  • Kim, Hong Pyo
  • Stolz, Donna B
  • Ryter, Stefan W
  • Choi, Augustine M K
Type
Published Article
Journal
American Journal of Respiratory Cell and Molecular Biology
Publisher
American Thoracic Society
Publication Date
Apr 01, 2012
Volume
46
Issue
4
Pages
507–514
Identifiers
DOI: 10.1165/rcmb.2009-0415OC
PMID: 22095627
Source
Medline
License
Unknown

Abstract

Epithelial cell death plays a critical role in hyperoxia-induced lung injury. We investigated the involvement of the autophagic marker microtubule-associated protein-1 light chain-3B (LC3B) in epithelial cell apoptosis after hyperoxia. Prolonged hyperoxia (>95% O(2)), which causes characteristic lung injury in mice, activated morphological and biochemical markers of autophagy. Hyperoxia induced the time-dependent expression and conversion of LC3B-I to LC3B-II in mouse lung in vivo and in cultured epithelial cells (Beas-2B, human bronchial epithelial cells) in vitro. Hyperoxia increased autophagosome formation in Beas-2B cells, as evidenced by electron microscopy and increased GFP-LC3 puncta. The augmented LC3B level after hyperoxia was transcriptionally regulated and dependent in part on the c-Jun N-terminal kinase pathway. We hypothesized that LC3B plays a regulatory role in hyperoxia-induced epithelial apoptosis. LC3B siRNA promoted hyperoxia-induced cell death in epithelial cells, whereas overexpression of LC3B conferred cytoprotection after hyperoxia. The autophagic protein LC3B cross-regulated the Fas apoptotic pathway by physically interacting with the components of death-inducing signaling complex. This interaction was mediated by caveolin-1 tyrosine 14, which is a known target of phosphorylation induced by hyperoxia. Taken together, hyperoxia-induced LC3B activation regulates the Fas apoptotic pathway and thus confers cytoprotection in lung epithelial cells. The interaction of LC3B and Fas pathways requires cav-1.

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