1. Academic Validation
  2. Activation of ERK induces phosphorylation of MAPK phosphatase-7, a JNK specific phosphatase, at Ser-446

Activation of ERK induces phosphorylation of MAPK phosphatase-7, a JNK specific phosphatase, at Ser-446

  • J Biol Chem. 2003 Aug 22;278(34):32448-56. doi: 10.1074/jbc.M213254200.
Kouhei Masuda 1 Hiroshi Shima Chiaki Katagiri Kunimi Kikuchi
Affiliations

Affiliation

  • 1 Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
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.

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