Integrin-linked kinase is involved in TNF-alpha-induced inducible nitric-oxide synthase expression in myoblasts.
Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic cytokine produced by activated macrophages. Nitric oxide (NO) is a highly reactive nitrogen radical implicated in inflammatory responses. We investigated the signaling pathway involved in inducible nitric oxide synthase (iNOS) expression and NO production stimulated by TNF-alpha in cultured myoblasts. TNF-alpha stimulation caused iNOS expression and NO production in myoblasts (G7 cells). TNF-alpha-mediated iNOS expression was attenuated by integrin-linked kinase (ILK) inhibitor (KP392) and siRNA. Pretreatment with Akt inhibitor, mammalian target of rapamycin (mTOR) inhibitor (rapamycin), NF-kappaB inhibitor (PDTC), and IkappaB protease inhibitor (TPCK) also inhibited the potentiating action of TNF-alpha. Stimulation of cells with TNF-alpha increased ILK kinase activity. TNF-alpha also increased the Akt and mTOR phosphorylation. TNF-alpha mediated an increase of NF-kappaB-specific DNA-protein complex formation, p65 translocation into nucleus, NF-kappaB-luciferase activity was inhibited by KP392, Akt inhibitor, and rapamycin. Our results suggest that TNF-alpha increased iNOS expression and NO production in myoblasts via the ILK/Akt/mTOR and NF-kappaB signaling pathway.
Department of Neurosurgery, Taichung Veterans General Hospital, Taichung, Taiwan.
Hsi-Kai
HK
Tsou
Chen-Ming
CM
Su
Hsien-Te
HT
Chen
Ming-Han
MH
Hsieh
Cheng-Jyh
CJ
Lin
Dah-Yuu
DY
Lu
Chih-Hsin
CH
Tang
Yi-Hung
YH
Chen
D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D032446:Myoblasts / Q000187:drug effects* / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000099200:Scaffold Protein ILK
D047908:Intracellular Signaling Peptides and Proteins; D052247:Nitric Oxide Synthase Type II; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D014409:Tumor Necrosis Factor-alpha; D000099200:Scaffold Protein ILK; C546843:mTOR protein, mouse