title: FAK activation is required for TNF-alpha-induced IL-6 production in myoblasts.
abstract: Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine produced by activated macrophages. IL-6 is a multifunctional cytokine that plays a central role in both innate and acquired immune responses. We investigated the signaling pathway involved in IL-6 production stimulated by TNF-alpha in cultured myoblasts. TNF-alpha caused concentration-dependent increases in IL-6 production. TNF-alpha-mediated IL-6 production was attenuated by focal adhesion kinase (FAK) mutant and siRNA. Pretreatment with phosphatidylinositol 3-kinase inhibitor (PI3K; Ly294002 and wortmannin), Akt inhibitor, NF-kappaB inhibitor (pyrrolidine dithiocarbamate, PDTC), and IkappaB protease inhibitor (L-1-tosylamido-2-phenyl phenylethyl chloromethyl ketone, TPCK) also inhibited the potentiating action of TNF-alpha. TNF-alpha increased the FAK, PI3K, and Akt phosphorylation. Stimulation of myoblasts with TNF-alpha activated IkappaB kinase alpha/beta (IKKalpha/beta), IkappaBalpha phosphorylation, p65 phosphorylation, and kappaB-luciferase activity. TNF-alpha mediated an increase of kappaB-luciferase activity which was inhibited by Ly294002, wortmannin, Akt inhibitor, PDTC and TPCK or FAK, PI3K, and Akt mutant. Our results suggest that TNF-alpha increased IL-6 production in myoblasts via the FAK/PI3K/Akt and NF-kappaB signaling pathway.
authors.affiliation: Graduate Institute of Sports and Health, National Changhua University of Education, Changhua County, Taiwan.
authors.forename: Wen-Pei
authors.initials: WP
authors.lastname: Tseng
authors.forename: Chen-Ming
authors.initials: CM
authors.lastname: Su
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Tang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000096:biosynthesis*; D051379:Mice; D024510:Muscle Development / Q000502:physiology*; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism*; D032446:Myoblasts / Q000166:cytology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D051058:Oncogene Protein v-akt / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D051417:Focal Adhesion Kinase 1; D015850:Interleukin-6; D016328:NF-kappa B; D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D014409:Tumor Necrosis Factor-alpha; C496051:Ptk2 protein, mouse