Distinct Binding Determinants for ERK2/p38α and JNK MAP Kinases Mediate Catalytic Activation and Substrate Selectivity of MAP Kinase Phosphatase-1

Abstract

Mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1/CL100) is an inducible nuclear dual specificity protein phosphatase that can dephosphorylate and inactivate both mitogen-and stress-activated protein kinases in vitro and in vivo. However, the molecular mechanism responsible for the substrate selectivity of MKP-1 is unknown. In addition, it has been suggested that the signal transducers and activators of transcription 1 (STAT1) transcription factor is a physiological non-MAP kinase substrate for MKP-1. We have used the yeast two-hybrid assay to demonstrate that MKP-1 is able to interact selectively with the extracellular signal-regulated kinase 1/2 (ERK1/2), p38␣, and c-Jun We conclude that the substrate selectivity of MKP-1 is determined by specific protein-protein interactions coupled with catalytic activation of the phosphatase and that these interactions are restricted to members of the MAP kinase family of enzymes.The mitogen-activated protein (MAP) 1 kinases are key components of cellular signal transduction pathways, which become activated in response to a wide variety of external stimuli. They can be subdivided into at least three classes based on sequence homology and differential activation by agonists (1-3); these include the growth factor-activated MAP kinases, extracellular signal-regulated kinase 1 (ERK1) and ERK2, and the stress-activated MAP kinases c-Jun amino-terminal kinase (JNK, SAPK1) and p38 (SAPK2) MAP kinases. In addition, a number of less well characterized members of the MAP kinase family have been identified such as BMK1/ERK5, ERK7, and ERK3 (4 -6). MAP kinase pathways relay, amplify, and integrate complex signals in order to elicit appropriate biological responses. In mammalian cells, these include cellular proliferation, differentiation, inflammatory responses, and apoptosis. These responses are associated with significant alterations in the pattern of cellular gene expression, and transcription factors are a major target of MAP kinase signaling in vivo (7). To phosphorylate these proteins, activated MAP kinases translocate to the cell nucleus, a process that is generally associated with prolonged activation of the MAP kinase (8). Therefore, the magnitude and duration of MAP kinase activation are critical determinants of biological outcome, and regulatory mechanisms governing the activation of MAP kinase are of key importance in both physiological and pathological cell functions.The duration and magnitude of MAP kinase activation can be regulated at many points within the signal transduction pathway. However, it is now clear that the MAP kinase itself is a major target for regulation through the action of specific protein phosphatases. MAP kinase activation is dependent on the phosphorylation of both the threonine and tyrosine residues of the TXY motif found within the "activation loop" of the kinase. Since phosphorylation of both residues is required for activity, dephosphorylation of either residue is sufficient for inactivation. This can be achieved by protein-tyrosine ph...

Activation of p42 Mitogen-activated Protein Kinase (MAPK), but not c-Jun NH2-Terminal Kinase, Induces Phosphorylation and Stabilization of MAPK PhosphataseXCL100 inXenopusOocytes

“…Moreover, p42 MAPK may positively regulate XCL100 through at least two other mechanisms: activation of p42 MAPK can induce expression of the closely related phosphatases MKP-1 and MKP-2 (Brondello et al, 1997), and, by analogy to other MKP family members, p42 MAPK may catalytically activate XCL100 by binding to its amino terminus (Camps et al, 1998;Dowd et al, 1998;Fjeld et al, 2000;Chen et al, 2001;Slack et al, 2001). The presence of multiple activation mechanisms may increase the robustness of the p42 MAPK/XCL100 system.…”

Activation of p38 mitogen-activated protein kinase abolishes insulin-mediated myocardial protection against ischemia-reperfusion injury

“…Given the fact that we observed a 23-fold increase in p38 MAPK phosphorylation in the ischemic area, we next examined the impact of p38 MAPK activation on insulin-mediated myocardial protection during the ischemia-reperfusion procedure by intravenously injecting anisomycin (2 mg/kg) 10 min before the onset of ischemia. Anisomycin, a translational inhibitor secreted by streptomycesspp., strongly activates p38 MAPK and JNK in mammalian cells (11,30,39), thus mimicking the effect of ischemia-reperfusion. As shown in Fig.…”

Priming of Glomerular Mesangial Cells by Activated Macrophages Causes Blunted Responses to Proinflammatory Stimuli

“…MKP-1 is induced through various mechanisms including the MAPK pathways per se and selectively binds and inactivates MAPKs including ERK1/2, JNK1/2, and p38 MAPK (43). To further investigate upstream events involved in the macrophage-primed tolerance of mesangial cells, we examined the level of MKP-1.…”