title: TBK1-targeted suppression of TRIF-dependent signaling pathway of Toll-like receptors by helenalin.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the therapeutic potential of the helenalin in Toll-like receptor (TLR) signaling pathways.
  
  
  METHODS
  RAW264.7 cells were transfected with a NF-κB, IFNβ PRDIII-I, or IP-10 luciferase plasmid and then luciferase enzyme activities were determined by luciferase assay. The expression of iNOS, COX-2, and IP-10 and phosphorylation of IRF3 were determined by Western blotting. The levels of IP-10 were determined with culture medium by using IP-10 ELISA kit. TBK1 kinase activity was determined by MBP assay kit.
  
  
  RESULTS
  Helenalin inhibited transcription factor NF-κB and IRF3 activation, which was induced by TLR agonists as well as its target genes, such as COX-2, iNOS, and IP-10. Helenalin attenuated ligand-independent activation of NF-κB induced by MyD88, IKKβ, and p65, and IRF3 induced by TRIF, TBK1, or IRF3. Furthermore, helenalin inhibited TBK1 kinase activity in vitro.
  
  
  CONCLUSIONS
  TLRs are primary sensors that detect a wide variety of microbial components and play an important role in the induction of innate immune. To evaluate the therapeutic potential of helenalin, we examined its effect on signal transduction via the TLR signaling pathways. Our results suggest that beneficial effects of helenalin on chronic inflammatory diseases are mediated through modulation of TLR signaling pathways by targeting TBK1.
authors.affiliation: Department of Medical Science, College of Medical Sciences, Soonchunhyang University, Asan-Si, Chungnam 336-745, Republic of Korea.
authors.forename: Hwa-Jeong
authors.initials: HJ
authors.lastname: Shin
authors.forename: Hyung-Sun
authors.initials: HS
authors.lastname: Youn
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D054357:Chemokine CXCL10 / Q000235:genetics; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism; D055666:Lipopeptides / Q000494:pharmacology; D051379:Mice; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012717:Sesquiterpenes / Q000494:pharmacology*; D045789:Sesquiterpenes, Guaiane; D015398:Signal Transduction / Q000187:drug effects*; D051193:Toll-Like Receptors / Q000819:agonists / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D054357:Chemokine CXCL10; D051546:Cyclooxygenase 2; D050838:Interferon Regulatory Factor-3; D055666:Lipopeptides; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; D017346:Protein Serine-Threonine Kinases; D012717:Sesquiterpenes; D045789:Sesquiterpenes, Guaiane; D051193:Toll-Like Receptors; C114753:CXCL10 protein, human; C494232:IRF3 protein, human; C476286:Ticam1 protein, mouse; C470409:TICAM1 protein, human; C001329:helenalin; C106335:macrophage stimulatory lipopeptide 2; C496540:PTGS2 protein, human; C498588:Tbk1 protein, mouse; C403191:TBK1 protein, human
keywords: Helenalin; LPS; TBK1; TRIF; Toll-like receptors