title: Roles of MAPK and NF-kappaB in interleukin-6 induction by lipopolysaccharide in vascular smooth muscle cells.
abstract: Toll-like receptor (TLR)-4 signaling promotes cytokine synthesis in vascular smooth muscle cells (VSMC). However, it is unknown how TLR-4 regulates interleukin-6 (IL-6) in VSMC. Therefore, the present study investigated cellular factors involved in TLR-4-mediated IL-6 in VSMC in terms of MAPK and transcription elements. Exposure of aortic smooth muscle cells to TLR4-specific lipopolysaccharide (LPS) not only enhanced IL-6 release but also induced IL-6 transcript via promoter activation. The promoter activation was attenuated by dominant-negative MKK1 and to a lesser extent by dominant-negative MKK3, but not by dominant-negative MKK4. IL-6 promoter activity was diminished by U0126 or SB202190, but not by SP600125. Co-transfection with dominant negative CCAAT/enhancer binding protein or with IkappaB suppressed LPS-induced promoter activation, whereas the promoter activity was not influenced by dominant negative c-Jun. Mutation in the IL-6 promoter region at the binding site of NF-kappaB or C/EBP impaired promoter activation in response to LPS. Further impairment occurred when both NF-kappaB- and C/EBP-binding sites were mutated. LPS-induced IL-6 promoter activation was also prevented by pretreatment with epigallocatechin 3-gallate, curcumin, and resveratrol. The present study reports that TLR4-agonistic LPS induces IL-6 through transcriptional activation in VSMC and ERK1/2, p38 MAPK, NF-kappaB, and C/EBP play active roles in that process.
authors.affiliation: Department of Pharmacology, School of Medicine, Pusan National University, Busan, Korea.
authors.forename: Yong-Hae
authors.initials: YH
authors.lastname: Son
authors.forename: Yeon-Tae
authors.initials: YT
authors.lastname: Jeong
authors.forename: Kyeong-Ah
authors.initials: KA
authors.lastname: Lee
authors.forename: Kyung-Ha
authors.initials: KH
authors.lastname: Choi
authors.forename: Sun-Mi
authors.initials: SM
authors.lastname: Kim
authors.forename: Byung-Yong
authors.initials: BY
authors.lastname: Rhim
authors.forename: Koanhoi
authors.initials: K
authors.lastname: Kim
mesh_terms: D001011:Aorta / Q000166:cytology / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000633:toxicity*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D015398:Signal Transduction; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases