title: 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, H2O2, 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.
authors.affiliation: Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Masuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shima
authors.forename: Chiaki
authors.initials: C
authors.lastname: Katagiri
authors.forename: Kunimi
authors.initials: K
authors.lastname: Kikuchi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002384:Catalysis; D054637:Dual-Specificity Phosphatases; D006367:HeLa Cells; D006801:Humans; D054639:Mitogen-Activated Protein Kinase Phosphatases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism*
chemical_list: D012694:Serine; D020928:Mitogen-Activated Protein Kinases; D054639:Mitogen-Activated Protein Kinase Phosphatases; C439065:DUSP16 protein, human; D054637:Dual-Specificity Phosphatases; D017027:Protein Tyrosine Phosphatases