title: TLR 2 induces vascular smooth muscle cell migration through cAMP response element-binding protein-mediated interleukin-6 production.
abstract: OBJECTIVE
  Migration of vascular smooth muscle cells (VSMCs) from the media into intima contributes to the development of atherosclerosis. Gene deletion experiments implicate a role for toll-like receptor 2 (TLR2) in atherogenesis. However, the underlying mechanisms remain unclear. We postulate that TLR2 promotes VSMC migration by enhancing interleukin (IL)-6 production.
  
  
  RESULTS
  Migration assays revealed that TLR2 agonists promoted VSMC migration but not cell proliferation or viability. TLR2 deficiency or inhibition of TLR2 signaling with anti-TLR2 antibody suppressed TLR2 agonist-induced VSMC migration and IL-6 production, which was mediated via p38 mitogen-associated protein kinase and extracellular signal-regulated kinase 1/2 signaling pathways. Neutralizing anti-IL-6 antibodies impaired TLR2-mediated VSMC migration and formation of filamentous actin fiber and lamellipodia. Blockade of p38 mitogen-associated protein kinase or extracellular signal-regulated kinase 1/2 activation inhibited TLR2 agonist pam3CSK4-induced phosphorylation of cAMP response element-binding protein, which regulates IL-6 promoter activity through the cAMP response element site. Moreover, cAMP response element-binding protein small interfering RNA inhibited pam3CSK4-induced IL-6 production and VSMC migration. Additionally, Rac1 small interfering RNA inhibited pam3CSK4-induced VSMC migration but not IL-6 production.
  
  
  CONCLUSIONS
  Our results suggest that on ligand binding, TLR2 activates p38 mitogen-associated protein kinase and extracellular signal-regulated kinase 1/2 signaling in VSMCs. These signaling pathways act in concert to activate cAMP response element-binding protein and subsequent IL-6 production, which in turn promotes VSMC migration via Rac1-mediated actin cytoskeletal reorganization.
authors.affiliation: Institute of Cellular and System Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan, Miaoli County 35053, Taiwan.
authors.forename: Guan-Lin
authors.initials: GL
authors.lastname: Lee
authors.forename: Ya-Wei
authors.initials: YW
authors.lastname: Chang
authors.forename: Jing-Yiing
authors.initials: JY
authors.lastname: Wu
authors.forename: Meng-Ling
authors.initials: ML
authors.lastname: Wu
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Wu
authors.forename: Shaw-Fang
authors.initials: SF
authors.lastname: Yet
authors.forename: Cheng-Chin
authors.initials: CC
authors.lastname: Kuo
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D050197:Atherosclerosis / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D055666:Lipopeptides / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism; D013997:Time Factors; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020830:rac1 GTP-Binding Protein; D000093242:Interleukin-6 Inhibitors
chemical_list: D057134:Antibodies, Neutralizing; D017362:Cyclic AMP Response Element-Binding Protein; D015850:Interleukin-6; D008024:Ligands; D055666:Lipopeptides; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009479:Neuropeptides; D047428:Protein Kinase Inhibitors; D051195:Toll-Like Receptor 2; D048051:p38 Mitogen-Activated Protein Kinases; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000093242:Interleukin-6 Inhibitors; C492004:Creb1 protein, mouse; C508075:Pam(3)CSK(4) peptide; C484602:Rac1 protein, mouse; C493486:Tlr2 protein, mouse; C535148:Mapk1 protein, mouse