title: Activation of mitogen-activated protein kinases and AP-1 by polysaccharide isolated from the radix of Platycodon grandiflorum in RAW 264.7 cells.
abstract: The root of Platycodon grandiflorum has been widely used for the treatment of various diseases in oriental medicine. Our previous study showed that the PG, a polysaccharide isolated from P. grandiflorum, activates macrophages via Toll-like receptor 4 (TLR4). However, the associated biological mechanisms are not fully understood. To elucidate the molecular mechanism responsible for the macrophage activation, we investigated the effect of PG on the activity of mitogen-activated protein kinases (MAPKs) and activator protein-1 (AP-1) in RAW 264.7 cells, a murine macrophage cell line. Treatment of RAW 264.7 cells with PG produced a marked induction of AP-1 DNA binding activity. Moreover, all three MAPKs were activated by PG, and PG-induced activation of MAPKs was abrogated by the treatment of PD98059, curcumin, and SB203580, specific inhibitors of MEK-1/2, stress-activated protein kinases/jun N-terminal kinase (SAPK/JNK), and p38 MAP kianse, respectively. The induction of AP-1 DNA binding activity by PG was also inhibited by these MAPK inhibitors. Moreover, supershift analysis identified that JunB and Fra-1 are major components involved in the PG-mediated induction of AP-1 DNA binding. Additionally, curcumin and SB203580 suppressed PG-induced production of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha), whereas PD98059 showed an inhibitory effect only on the TNF-alpha production. Taken together, these results suggest that macrophage activation by PG is mediated, at least in part, by MAPKs and AP-1.
authors.affiliation: Korea Research Institute of Bioscience and Biotechnology, Biopotency Evaluation Center, 52 Oun-dong, Yusong-gu, Taejon, 305-333, South Korea.
authors.forename: Yeo Dae
authors.initials: YD
authors.lastname: Yoon
authors.forename: Jong Soon
authors.initials: JS
authors.lastname: Kang
authors.forename: Sang Bae
authors.initials: SB
authors.lastname: Han
authors.forename: Song-Kyu
authors.initials: SK
authors.lastname: Park
authors.forename: Hyun Sun
authors.initials: HS
authors.lastname: Lee
authors.forename: Jong Seong
authors.initials: JS
authors.lastname: Kang
authors.forename: Hwan Mook
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D008262:Macrophage Activation / Q000187:drug effects* / Q000276:immunology; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000276:immunology; D052247:Nitric Oxide Synthase Type II; D018517:Plant Roots / Q000737:chemistry; D031238:Platycodon / Q000737:chemistry*; D011134:Polysaccharides / Q000302:isolation & purification / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; D011134:Polysaccharides; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D020928:Mitogen-Activated Protein Kinases