Several Dual Specificity Phosphatases Coordinate to Control the Magnitude and Duration of JNK Activation in Signaling Response to Oxidative Stress

Institute of Biological Chemistry, Academia Sinica, 128 Academia Rd., Section 2, Taipei 11529, Taiwan.
Journal of Biological Chemistry (Impact Factor: 4.57). 10/2007; 282(39):28395-407. DOI: 10.1074/jbc.M705142200
Source: PubMed


Mitogen-activated protein kinases (MAPKs) are important mediators that integrate signaling from upstream pathways in response to various environmental cues. In order to control appropriate gene expression through phosphorylation of transcription factors, the activity of MAPKs must be tightly regulated by the actions coordinated between protein kinases and phosphatases. In this study, we explore the underlying mechanism through which the oxidative stress-activated c-Jun N-terminal kinases (JNKs), members of MAPKs, are regulated by dual specificity phosphatases (DUSPs). DUSPs are a group of enzymes that belong to the superfamily of protein-tyrosine phosphatases. They are able to recognize phospho-Ser/Thr and phospho-Tyr residues in substrates. Using quantitative real time PCR, we found that stimulation of human embryonic kidney 293T cells with H(2)O(2) or xanthine/xanthine oxidase led to inducible expression of multiple DUSPs. We used RNA interference to characterize the functional role of these DUSPs and found rapid and transient induction of DUSP1 and DUSP10 to be essential for determining the appropriate magnitude of JNK activation in response to oxidative stress. The transcription factor ATF2, which is phosphorylated and activated by JNK, is a critical mediator for inducible expression of DUSP1 and DUSP10 in this signaling pathway. We further demonstrated that DUSP4 and DUSP16, both showing significant late phase induction, dephosphorylate JNK effectively, causing the down-regulation of the signaling cascade. Thus, this study provides new insights into the role of several DUSPs that coordinate with each other to control the magnitude and duration of JNK activity in response to oxidative stress.

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    • "MKP-1, a protein phosphatase with dual specificity (Ser/Thr or Thr/Tyr), is responsible for the inactivation of JNK and p38, and therefore controls MAPK-dependent inflammation during the innate immune response [20,21]. Because MKP-1 activity has reported to be regulated by oxidative stress [22], we hypothesized that XO-derived ROS might contribute to decreased MKP-1 activity following LPS stimulation. Supporting this hypothesis, NAC-mediated inactivation of JNK was abolished by orthovanadate or Ro-31-8220 (Figure 6A), and decrease in MKP-1 activity by LPS was recovered by NAC (data not shown). "
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    ABSTRACT: Excess reactive oxygen species (ROS) formation can trigger various pathological conditions such as inflammation, in which xanthine oxidase (XO) is one major enzymatic source of ROS. Although XO has been reported to play essential roles in inflammatory conditions, the molecular mechanisms underlying the involvement of XO in inflammatory pathways remain unclear. Febuxostat, a selective and potent inhibitor of XO, effectively inhibits not only the generation of uric acid but also the formation of ROS. In this study, therefore, we examined the effects of febuxostat on lipopolysaccharide (LPS)-mediated inflammatory responses. Here we show that febuxostat suppresses LPS-induced MCP-1 production and mRNA expression via activating MAPK phosphatase-1 (MKP-1) which, in turn, leads to dephosphorylation and inactivation of JNK in macrophages. Moreover, these effects of febuxostat are mediated by inhibiting XO-mediated intracellular ROS production. Taken together, our data suggest that XO mediates LPS-induced phosphorylation of JNK through ROS production and MKP-1 inactivation, leading to MCP-1 production in macrophages. These studies may bring new insights into the novel role of XO in regulating inflammatory process through MAPK phosphatase, and demonstrate the potential use of XO inhibitor in modulating the inflammatory processes.
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    • "We observed that Dusp10 is up-regulated at 8 hours post SB1117 infection, but no expression change was observed at 8 hours post SL1344 infection (Figure 8C). Because DUSP10 negatively regulates JNK and p38MAPK [47,48], we reasoned that AvrA may stabilize DUSP10 expression to inhibit activation of JNK pathway at the early stage of SL1344 infection. However, more up-regulated and down-regulated genes that participate in response to the MAPKK signaling cascade are involved at the late stage of both SL1344 and SB1117 infection, there is no clear evidence that AvrA functions differently in the SAPK/JNK pathway at the late stage. "
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    • "duspl, therefore, might be involved in regulating the migration of ECs in growing and regenerating fin rays to promote the formation of new blood vessels . As a MAP kinase phosphatase, Dusp1 is likely to regulate the activity of MAP kinases (Teng et al., 2007; Caunt et al., 2008) that transmit the Vegf signal (Chakroborty et al., 2008; Kinneyet al., 2008). Inhibition ofVegf signalling (Bayliss et al., 2006) or knockdown of duspl in the zebrafish system will be helpful to validate or reject this hypothesis. "
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