title: MAPK/AP-1 activation mediates TLR2 agonist-induced SPLUNC1 expression in human lung epithelial cells.
abstract: BACKGROUND
  Short Palate Lung and Nasal epithelium Clone 1 (SPLUNC1) is a newly described host defense protein, primarily expressed in large airway epithelial cells. Reduced SPLUNC1 has been reported in allergic and cigarette smoke-exposed airways. We found that Mycoplasma pneumoniae increases SPLUNC1 in airway epithelium in part via activating TLR2-NF-κB pathway. However, the contribution of additional signaling pathways to TLR2-mediated SPLUNC1 expression remains unclear. In the present study, we investigated if TLR2-induced mitogen-activated protein kinase (MAPK)/activator protein-1 (AP-1) signaling regulates SPLUNC1 expression in human lung epithelial cells.
  
  
  METHODS
  Human lung epithelial NCI-H292 cells were stimulated with a TLR2 agonist Palmitoyl (3)-Cys-Ser-Lys (4)-OH (Pam(3)CSK(4)). MAPK/AP-1 activation and its role in SPLUNC1 regulation were investigated by Western blot, c-Jun activation assay, chromatin immunoprecipitation (ChIP) and real-time PCR. SPLUNC1 promoter activity was assessed by a luciferase reporter assay.
  
  
  RESULTS
  Pam(3)CSK(4) increased SPLUNC1 expression in NCI-H292 cells in a dose- and time-dependent manner, and enhanced SPLUNC1 promoter activity. Pam(3)CSK(4)-treated cells demonstrated activated MAPK and c-Jun compared to untreated cells. ChIP assay indicated increased c-Jun binding to the SPLUNC1 promoter following Pam(3)CSK(4) stimulation. Inhibition of ERK1/2 significantly reduced Pam(3)CSK(4)-mediated c-Jun activation and SPLUNC1 expression.
  
  
  CONCLUSIONS
  Our results for the first time demonstrate that TLR2-mediated MAPK/AP-1 activation up-regulates lung epithelial SPLUNC1 expression at the transcriptional level. Understanding SPLUNC1 gene regulation should provide more specific therapeutic targets to restore deficient SPLUNC1 production in diseased airways.
authors: Department of Medicine, National Jewish Health, University of Colorado Denver, Denver, CO 80206, USA.
authors: Jyoti
authors: J
authors: Thaikoottathil
authors: Hong Wei
authors: HW
authors: Chu
mesh_terms: D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008074:Lipoproteins / Q000494:pharmacology*; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D051195:Toll-Like Receptor 2 / Q000037:antagonists & inhibitors*; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: C485599:BPIFA1 protein, human; D006023:Glycoproteins; D008074:Lipoproteins; D010750:Phosphoproteins; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D018808:Transcription Factor AP-1; C061108:N-palmitoyl-S-(2,3-bis(palmitoyloxy)propyl)cysteinyl-seryl-lysyl-lysyl-lysyl-lysine; D020928:Mitogen-Activated Protein Kinases