Document Detail


Endoplasmic reticulum stress induced by surfactant protein C BRICHOS mutants promotes proinflammatory signaling by epithelial cells.
MedLine Citation:
PMID:  20463293     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Chronic interstitial lung disease in both adults and children is associated with mutations of the surfactant protein C (SP-C) proprotein. Among these, mutations within the distal COOH propeptide, known as the BRICHOS domain, are associated with a severe disease phenotype. We showed that prolonged expression of the BRICHOS mutants, SP-C(Δexon4) and SP-C(L188Q), destabilizes endoplasmic reticulum (ER) quality-control mechanisms (the unfolded protein response, or UPR), resulting in the induction of ER stress signaling, an inhibition of the ubiquitin/proteasome system, and the activation of apoptotic pathways. Based on recent observations that the UPR and ER stress can be linked to the induction of proinflammatory signaling, we hypothesized that the epithelial cell dysfunction mediated by SP-C BRICHOS mutants would activate proinflammatory signaling pathways. In a test of this hypothesis, A549 and human embryonic kidney epithelial (HEK293) cells, transiently transfected with either SP-C(Δexon4) or SP-C(L188Q) mutants, each promoted the upregulation of multiple UPR response genes, including homocysteine-inducible, endoplasmic reticulum stress-inducible, ubiquitin-like domain member 1 (HERPUD1) and GRP78. Commensurate with these results, increases in IL-8 secretion occurred and were accompanied by the activation of c-Jun N-terminal kinase (JNK)/activating protein-1 signaling. The stimulation of IL-8 cytokine release was completely attenuated by treatment with the JNK-specific inhibitor, SP600125. In addition, SP-C(Δexon4), but not SP-C(L188Q), activated NFκB. The treatment of SP-C(Δexon4) transfected cells with 4-phenylbutyric acid, a small molecule chaperone known to improve protein folding, blocked the activation of NFκB, but not the release of IL-8. Taken together, the results support the role of JNK signaling in mediating SP-C BRICHOS-induced cytokine release, and provide a link between SP-C BRICHOS mutants and proinflammatory cytokine signaling.
Authors:
Jean Ann Maguire; Surafel Mulugeta; Michael F Beers
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-05-12
Journal Detail:
Title:  American journal of respiratory cell and molecular biology     Volume:  44     ISSN:  1535-4989     ISO Abbreviation:  Am. J. Respir. Cell Mol. Biol.     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-03-02     Completed Date:  2011-04-27     Revised Date:  2012-03-01    
Medline Journal Info:
Nlm Unique ID:  8917225     Medline TA:  Am J Respir Cell Mol Biol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  404-14     Citation Subset:  IM    
Affiliation:
Surfactant Biology Laboratories, Pulmonary and Critical Care Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, USA.
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MeSH Terms
Descriptor/Qualifier:
Cell Line
Cell Line, Tumor
Cytokines / metabolism
Endoplasmic Reticulum / metabolism*
Epithelial Cells / cytology*
Humans
Inflammation
Interleukin-8 / metabolism
Lung Diseases, Interstitial / pathology
Membrane Proteins / metabolism
Models, Biological
NF-kappa B / metabolism
Polymerase Chain Reaction / methods
Pulmonary Surfactant-Associated Protein C / metabolism*
Signal Transduction
Grant Support
ID/Acronym/Agency:
2T32 HL007748/HL/NHLBI NIH HHS; HL 087177/HL/NHLBI NIH HHS; HL 090732/HL/NHLBI NIH HHS; HL 19737/HL/NHLBI NIH HHS; P30-ES013508/ES/NIEHS NIH HHS
Chemical
Reg. No./Substance:
0/Cytokines; 0/HERPUD1 protein, human; 0/Interleukin-8; 0/Membrane Proteins; 0/NF-kappa B; 0/Pulmonary Surfactant-Associated Protein C

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