Reactive Oxygen Species Mediate Cytokine Activation of c-Jun NH2-terminal Kinases

Abstract

Interleukin 1 (IL-1) and tumor necrosis factor alpha (TNFalpha) are known to induce production of reactive oxygen species (ROS), which have been suggested to act as second messengers. Here we demonstrate that ROS production by bovine chondrocytes upon cytokine stimulation induces c-jun expression. Since c-jun expression is regulated by its own gene product via phosphorylation by c-Jun NH2-terminal kinases (JNKs), we investigated if cytokines and ROS could modulate JNK activity in chondrocyte monolayer cultures. Treatment of bovine chondrocytes with both IL-1 and TNFalpha leads to rapid induction of JNK activity, stimulating JNK activity 7- and 20-fold, respectively. Importantly, the observation that antioxidant treatment antagonizes IL-1 and TNFalpha activation of JNK provides strong evidence that ROS can act as mediators of JNK activity. Moreover, potent activation of JNK is also observed by direct addition of the ROS hydrogen peroxide (H2O2) to the chondrocyte cultures. Nitric oxide (NO), a multifunctional ROS, also appears to simulate JNK, albeit to a lesser extent. These findings identify JNK as another molecular target for the actions of NO and H2O2. In addition, the inhibitory effect of diphenyleneiodonium on JNK activation implicates the involvement of flavonoid-containing enzymes in the ROS-mediated signaling process. Overstimulation of JNK activity by excessive production of ROS may, therefore, underlie pathological conditions such as arthritis and cancer.

Overexpression of γ-glutamylcysteine synthetase suppresses tumor necrosis factor-induced apoptosis and activation of nuclear transcription factor-kappa B and activator protein-1

“…This kinase is activated in response to di erent kinds of stress and is needed for activation of AP-1. In addition cytokines are known to activate JNK through generation of ROI (Gomez del Arco et al, 1996;Lo et al, 1996;Wilhelm et al, 1997;Esposito et al, 1994). As shown in Figure 6a, TNF activated JNK in control cells in a time-dependent manner, with 5 ± 6-fold activation noted with 1000 pM TNF within 5 min.…”

“…Whether GSH plays any role in TNF-induced activation of JNK and MEK has not previously been reported, but both have been shown to be redoxsensitive Gomez del Arco et al, 1996;Lo et al, 1996;Wilhelm et al, 1997). Since JNK and MEK have been shown to be involved in activation of AP-1 and NF-kB, respectively (Westwick et al, 1994;Lee et al, 1997), it is possible that suppression of these kinases by g-GCS generated GSH leads to suppression of the transcription factors.…”

Differential Requirement for p56lck in HIV-tat Versus TNF-Induced Cellular Responses: Effects on NF-κB, Activator Protein-1, c-Jun N-Terminal Kinase, and Apoptosis

“…The activation of these cellular responses requires the generation of ROI (29,35,43,44). For instance, overexpression of antioxidant enzymes superoxide dismutase and ␥-glutamylcysteine synthetase has been shown to suppress the activation of NF-B, AP-1, JNK, MEK, and apoptosis (26,45).…”

Cellular redox state alters recombinant adeno-associated virus transduction through tyrosine phosphatase pathways

“…UV irradiation, ionizing radiation and HU treatment have all been previously demonstrated to generate ROIs, cause DNA damage directly and modulate redox sensitive signal transduction pathways, such as p53, NF-B, and JNK. [26][27][28][29][30][31] We hypothesized that ROIs may play a common role in the augmentation of rAAV transduction by these environmental stimuli. Findings that H 2 O 2 treatment of Hela cells before rAAV infection gives rise to similar increases in transduction as seen with UV and HU treatment support this hypothesis.…”