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

T. Matsuguchi, T. Musikacharoen, T. R. Johnson, A. S. Kraft, Y. Yoshikai

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

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-α), 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-α 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.

Original languageEnglish (US)
Pages (from-to)6999-7009
Number of pages11
JournalMolecular and cellular biology
Volume21
Issue number20
DOIs
StatePublished - 2001

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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