title: c-Jun N-terminal kinase attenuates TNFα signaling by reducing Nox1-dependent endosomal ROS production in vascular smooth muscle cells.
abstract: Tumor necrosis factor-α (TNFα), a proinflammatory cytokine, causes vascular smooth muscle cell (VSMC) proliferation and migration and promotes inflammatory vascular lesions. Nuclear factor-kappa B (NF-κB) activation by TNFα requires endosomal superoxide production by Nox1. In endothelial cells, TNFα stimulates c-Jun N-terminal kinase (JNK), which inhibits NF-κB signaling. The mechanism by which JNK negatively regulates TNFα-induced NF-κB activation has not been defined. We hypothesized that JNK modulates NF-κB activation in VSMC, and does so via a Nox1-dependent mechanism. TNFα-induced NF-κB activation was TNFR1- and endocytosis-dependent. Inhibition of endocytosis with dominant-negative dynamin (DynK44A) potentiated TNFα-induced JNK activation, but decreased ERK activation, while p38 kinase phosphorylation was not altered. DynK44A attenuated intracellular, endosomal superoxide production in wild-type (WT) VSMC, but not in NADPH oxidase 1 (Nox1) knockout (KO) cells. siRNA targeting JNK1 or JNK2 potentiated, while a JNK activator (anisomycin) inhibited, TNFα-induced NF-κB activation in WT, but not in Nox1 KO cells. TNFα-stimulated superoxide generation was enhanced by JNK1 inhibition in WT, but not in Nox1 KO VSMC. These data suggest that JNK suppresses the inflammatory response to TNFα by reducing Nox1-dependent endosomal ROS production. JNK and endosomal superoxide may represent novel targets for pharmacologic modulation of TNFα signaling and vascular inflammation.
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA. Electronic address: hyehun.choi@gmail.com.
authors.forename: Hyehun
authors.initials: H
authors.lastname: Choi
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Dikalova
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Stark
authors.affiliation: Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Fred S
authors.initials: FS
authors.lastname: Lamb
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004705:Endocytosis; D011992:Endosomes / Q000201:enzymology*; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D032389:Myocytes, Smooth Muscle / Q000201:enzymology*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D016328:NF-kappa B / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000378:metabolism; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D016328:NF-kappa B; D017382:Reactive Oxygen Species; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; C506236:Tnfrsf1a protein, mouse; D014409:Tumor Necrosis Factor-alpha; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; C000614711:NOX1 protein, mouse; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases
keywords: Endosome; NADPH oxidase 1; Superoxide; Tumor necrosis factor-α; c-Jun N-terminal kinase