Activation of ERK Induces Phosphorylation of MAPK Phosphatase-7, a JNK Specific Phosphatase, at Ser-446

Abstract

We previously showed that MKP-7 suppresses MAPK activation in COS-7 cells in the order of selectivity, JNK > > p38 > ERK, but interacts with ERK as well as JNK and p38. In this study we found that, when expressed in COS-7 cells with HA-ERK2, the mobility of FLAG-MKP-7 was decreased on SDS-PAGE gels depending on several stimuli, including phorbol 12-myristate 13-acetate, fetal bovine serum, epidermal growth factor, H 2 O 2 , and ionomycin. By using U0126, a MEK inhibitor, and introducing several point mutations, we demonstrated that this upward mobility shift is because of phosphorylation and identified Ser-446 of MKP-7 as the phosphorylation site targeted by ERK activation. To determine how MKP-7 interacts with MAPKs, we identified three domains in MKP-7 required for interaction with MAPKs, namely, putative MAP kinase docking domains (D-domain) I and II and a long COOH-terminal stretch unique to MKP-7. The D-domain I is required for interaction with ERK and p38, whereas the D-domain II is required for interaction with JNK and p38, which is likely to be important for MKP-7 to suppress JNK and p38 activations. The COOH-terminal stretch of MKP-7 was shown to determine JNK preference for MKP-7 by masking MKP-7 activity toward p38 and is a domain bound by ERK. These data strongly suggested that Ser-446 of MKP-7 is phosphorylated by ERK. Mitogen-activated protein kinases (MAPKs)1 are critical components of signal transduction pathways and mediate the cellular response to numerous extracellular stimuli, ranging from growth factors to environmental stress (1-4). Five MAPK pathways have been identified in eukaryotic cells, of which three are relatively well characterized: the extracellular signalregulated kinase (ERK) pathway, the c-Jun amino-terminal kinase (JNK) pathway, and the p38 pathway. The activation of MAPK is strictly regulated by two upstream kinases, MAPK kinase (MAPKK) and MAPK kinase kinase (MAPKKK). MAPKKKs, such as Raf, MEKK, MLK, and ASK1, phosphorylate and activate MAPKK. MAPKK is a dual-specificity protein kinase that phosphorylates tyrosine and threonine residues in a TXY motif of MAPK, leading to the full activation of MAPK (5). Once activated, MAPK can translocate from the cytoplasm to the nucleus, leading to phosphorylation of several transcription factors and altered regulation of gene expression (6, 7). The physiological functions of various MAPK subfamilies have been studied extensively in many systems. In general, activation of the ERK cascade leads to cell proliferation, differentiation, and enhanced cell survival after cellular stress, although in certain situations, ERK activation is required for the execution of apoptosis (8, 9). On the other hand, activation of the JNK and p38 cascades are usually associated with enhanced apoptosis and production of inflammatory cytokines (3, 10 -12), although there are notable exceptions in which JNK/p38 is necessary for cell proliferation and differentiation (13,14). Because MAP kinase pathways play important roles in regulating many critical cellular pr...

Increased Mitogen-Activated Protein Kinase Activity and TNF-α Production Associated with Mycobacterium smegmatis- but Not Mycobacterium avium-Infected Macrophages Requires Prolonged Stimulation of the Calmodulin/Calmodulin Kinase and Cyclic AMP/Protein Kinase A Pathways

“…In addition, cross talk between the MAPK pathways has been shown previously (37)(38)(39), where the inhibition of one kinase increases the activation state of the other. This could be through regulation of MAPK-specific phosphatases (40); however, the exact mechanism for this cross talk is presently unclear.…”

The anti‐tumour compound, RH1, causes mitochondria‐mediated apoptosis by activating c‐Jun N‐terminal kinase

“…Previous studies showed that ERK has been reported to increase the expression and activity of MKP2 and MKP7 (Paumelle et al, 2000;Masuda et al, 2003;Katagiri et al, 2005), which suppress JNK activation (Paumelle et al, 2000). Therefore, it seemed that activation of ERK was responsible for the decrease in JNK activity from 2 h after RH1 treatment in NQO1…”

Reciprocal Regulation between Slt2 MAPK and Isoforms of Msg5 Dual-specificity Protein Phosphatase Modulates the Yeast Cell Integrity Pathway

“…Recently, a basic motif-based docking domain, present in different types of MAPK-interacting proteins, has been shown to be involved in their association with MAPKs (43). This domain is composed of three motifs: a cluster of basic residues, a LXL element, and a cluster of hydrophobic residues, although the presence of two of these submotifs has been shown to be enough for binding to MAPKs (44). Msg5 does not present CH2 domains (10) but in silico analysis has revealed that the two forms of the phosphatase exhibited a domain of amino acid similarity to docking domains at the N-terminal region.…”