title: A novel mitogen-activated protein kinase phosphatase is an important negative regulator of lipopolysaccharide-mediated c-Jun N-terminal kinase activation in mouse macrophage cell lines.
abstract: We have isolated a cDNA homologous to known dual-specificity phosphatases from a mouse macrophage cDNA library and termed it MKP-M (for mitogen-activated protein kinase phosphatase isolated from macrophages). Three other presumed splice variant isoforms have also been identified for MKP-M. The longest and most abundant mRNA contains an open reading frame corresponding to 677 amino acids and produces an 80-kDa protein. The deduced amino acid sequence of MKP-M is most similar to those of hVH-5 (or mouse M3/6) and VHP1, a Caenorhabditis elegans tyrosine phosphatase. It includes an N-terminal rhodanase homology domain, the extended active-site sequence motif (V/L)X(V/I)HCXAG(I/V)SRSXT(I/V)XXAY(L/I)M (where X is any amino acid), and a C-terminal PEST sequence. Northern blot analysis revealed a dominant MKP-M mRNA species of approximately 5.5 kb detected ubiquitously among all tissues examined. MKP-M was constitutively expressed in mouse macrophage cell lines, and its expression levels were rapidly increased by lipopolysaccharide (LPS) stimulation but not by tumor necrosis factor alpha (TNF-alpha), gamma interferon, interleukin-2 (IL-2), or IL-15 stimulation. Immunocytochemical analysis showed MKP-M to be present within cytosol. When expressed in COS7 cells, MKP-M blocks activation of mitogen-activated protein kinases with the selectivity c-Jun N-terminal kinase (JNK) >> p38 = extracellular signal-regulated kinase. Furthermore, expression of a catalytically inactive form of MKP-M in a mouse macrophage cell line increased the intensity and duration of JNK activation and TNF-alpha secretion after LPS stimulation, suggesting that MKP-M is at least partially responsible for the desensitization of LPS-mediated JNK activation and cytokine secretion in macrophages.
authors.affiliation: Laboratory of Host Defense and Germfree Life, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Nagoya 466-8550, Japan. tmatsugu@med.nagoya-u.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Matsuguchi
authors.forename: T
authors.initials: T
authors.lastname: Musikacharoen
authors.forename: T R
authors.initials: TR
authors.lastname: Johnson
authors.forename: A S
authors.initials: AS
authors.lastname: Kraft
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshikai
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D019556:COS Cells; D002384:Catalysis; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D054637:Dual-Specificity Phosphatases; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D015723:Gene Library; D005799:Genes, Dominant; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000494:pharmacology; D019409:Interleukin-15 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D008070:Lipopolysaccharides / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D054639:Mitogen-Activated Protein Kinase Phosphatases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D018076:DNA, Complementary; D019409:Interleukin-15; D007376:Interleukin-2; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D014443:Tyrosine; D007371:Interferon-gamma; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D054639:Mitogen-Activated Protein Kinase Phosphatases; D010744:Phosphoric Monoester Hydrolases; D054637:Dual-Specificity Phosphatases; C438002:Dusp16 protein, mouse; D017027:Protein Tyrosine Phosphatases