MKP-7, a novel mitogen-activated protein kinase phosphatase, functions as a shuttle protein.
Mitogen-activated protein kinase (MAPK) phosphatases (MKPs) negatively regulate MAPK activity. In the present study, we have identified a novel MKP, designated MKP-7, and mapped it to human chromosome 12p12. MKP-7 possesses a long C-terminal stretch containing both a nuclear export signal and a nuclear localization signal, in addition to the rhodanese-like domain and the dual specificity phosphatase catalytic domain, both of which are conserved among MKP family members. When expressed in mammalian cells MKP-7 protein was localized exclusively in the cytoplasm, but this localization became exclusively nuclear following leptomycin B treatment or introduction of a mutation in the nuclear export signal. These findings indicate that MKP-7 is the first identified leptomycin B-sensitive shuttle MKP. Forced expression of MKP-7 suppressed activation of MAPKs in COS-7 cells in the order of selectivity, JNK p38 > ERK. Furthermore, a mutant form MKP-7 functioned as a dominant negative particularly against the dephosphorylation of JNK, suggesting that MKP-7 works as a JNK-specific phosphatase in vivo. Co-immunoprecipitation experiments and histological analysis suggested that MKP-7 determines the localization of MAPKs in the cytoplasm.
Masuda
K
K
Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
Shima
H
H
Watanabe
M
M
Kikuchi
K
K
D021581:Active Transport, Cell Nucleus; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000378:metabolism; D002874:Chromosome Mapping; D002881:Chromosomes, Human, Pair 12; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D019992:Databases as Topic; D054637:Dual-Specificity Phosphatases; D005091:Exons; D020224:Expressed Sequence Tags; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005799:Genes, Dominant; D006367:HeLa Cells; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020935:MAP Kinase Signaling System; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D054639:Mitogen-Activated Protein Kinase Phosphatases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014018:Tissue Distribution; D014162:Transfection; D048051:p38 Mitogen-Activated Protein Kinases
D002352:Carrier Proteins; D018076:DNA, Complementary; D005231:Fatty Acids, Unsaturated; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D054639:Mitogen-Activated Protein Kinase Phosphatases; C439065:DUSP16 protein, human; D054637:Dual-Specificity Phosphatases; D017027:Protein Tyrosine Phosphatases; C038753:leptomycin B