51
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Sekine Y, Tsuji S, Ikeda O, Sato N, Aoki N, Aoyama K, Sugiyama K, Matsuda T. Regulation of STAT3-mediated signaling by LMW-DSP2. Oncogene 2006; 25:5801-6. [PMID: 16636663 DOI: 10.1038/sj.onc.1209578] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Signal transducer and activator of transcription 3 (STAT3), which mediates biological actions in many physiological processes, is activated by cytokines and growth factors, and has been reported to be constitutively activated in numerous cancer cells. In this study, we examined whether low molecular weight-dual specificity phosphatase two (LMW-DSP2) is involved in the regulation of the interleukin 6 (IL-6)/leukemia inhibitory factor (LIF)/STAT3-mediated signaling pathway. IL-6/LIF-induced LMW-DSP2 expression in murine testicular or hepatoma cell lines, while LMW-DSP2 overexpression in 293T cells suppressed IL-6-induced phosphorylation and activation of STAT3. Furthermore, LMW-DSP2 suppressed the expression of IL-6-induced endogenous genes. In contrast, small-interfering RNA-mediated reduction of LMW-DSP2 expression enhanced IL-6-induced STAT3-dependent transcription. In fact, LMW-DSP2 interacted with STAT3 in vivo and endogenous LMW-DSP2 bound to STAT3 in murine testicular GC-1 cells. These results strongly suggest that LMW-DSP2 acts as a negative regulator of the IL-6/LIF/STAT3-mediated signaling pathway.
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Affiliation(s)
- Y Sekine
- Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan
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52
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Tanzola MB, Kersh GJ. The dual specificity phosphatase transcriptome of the murine thymus. Mol Immunol 2006; 43:754-62. [PMID: 16360020 DOI: 10.1016/j.molimm.2005.03.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 03/04/2005] [Indexed: 10/25/2022]
Abstract
Properly regulated mitogen-activated protein (MAP) kinase activity is critical for normal thymocyte development. MAP kinases are activated by phosphorylation of tyrosine and threonine, and dual specificity phosphatases (DUSPs) can inactivate MAP kinases by dephosphorylating both tyrosine and threonine. However, a role for DUSPs in thymocyte development has not been described. In this study, we have defined the subset of DUSP genes expressed in the murine thymus, and how their expression varies in different thymocyte subsets. Of the murine DUSP genes screened that could potentially dephosphorylate MAP kinases, we found 10 transcribed in the thymus. Seven of these 10 thymic DUSPs are true MAP kinase phosphatases based on the presence of a MAP kinase binding domain and demonstrated phosphatase activity against MAP kinases. Six of the seven thymic MAP kinase phosphatases have been shown to dephosphorylate extracellular regulated kinase (ERK). Quantitative PCR analysis of thymocyte populations isolated from different developmental stages revealed significant changes in DUSP expression as thymocytes progressed through development. Specifically, DUSPs 1, 4, and 5 significantly increase in expression as cells go from small, resting CD4/CD8 double positive cells to the CD4 single positive stage. Additionally, in vitro experiments showed that DUSPs could respond to TCR signaling, as anti-CD3 stimulation of thymocytes transiently increased transcription of six of the 10 thymic DUSP genes within 30 min. Notably, the ERK-specific phosphatase DUSP5 was upregulated 43-fold within 30 min, and returned to baseline within 24 h. Overall, we have identified a subset of DUSPs that could potentially regulate ERK activation in response to TCR signals in thymocytes.
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Affiliation(s)
- Melinda B Tanzola
- Graduate Program in Immunology and Molecular Pathogenesis, Emory University School of Medicine, 7311 WMB, 101 Woodruff Circle, Atlanta, GA 30322, USA
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53
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Takagaki K, Satoh T, Tanuma N, Masuda K, Takekawa M, Shima H, Kikuchi K. Characterization of a novel low-molecular-mass dual-specificity phosphatase-3 (LDP-3) that enhances activation of JNK and p38. Biochem J 2005; 383:447-55. [PMID: 15281913 PMCID: PMC1133737 DOI: 10.1042/bj20040498] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have isolated a mouse cDNA for a novel dual-specificity phosphatase designated LDP-3 (low-molecular-mass dual-specificity phosphatase 3). The 450 bp open reading frame encodes a protein of 150 amino acids with a predicted molecular mass of 16 kDa. Northern blot and reverse transcription-PCR analyses show that LDP-3 transcripts are expressed in almost all mouse tissues examined. In vitro analyses using several substrates and inhibitors indicate that LDP-3 possesses intrinsic dual-specificity phosphatase activity. When expressed in mammalian cells, LDP-3 protein is localized mainly to the apical submembrane area. Forced expression of LDP-3 does not alter activation of ERK (extracellular-signal-regulated kinase), but rather enhances activation of JNK (c-Jun N-terminal kinase) and p38 and their respective upstream kinases MKK4 (mitogen-activated protein kinase kinase 4) and MKK6 in cells treated with 0.4 M sorbitol. By screening with a variety of stimuli, we found that LDP-3 specifically enhances the osmotic stress-induced activation of JNK and p38.
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Affiliation(s)
- Kentaro Takagaki
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
| | - Takeshi Satoh
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
| | - Nobuhiro Tanuma
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
| | - Kouhei Masuda
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
| | - Mutsuhiro Takekawa
- †Division of Molecular Cell Signaling, Institute of Medical Science, The University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
- ‡PRESTO, Japan Science and Technology Corporation (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Hiroshi Shima
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
- To whom correspondence should be addressed (email )
| | - Kunimi Kikuchi
- *Division of Biochemical Oncology and Immunology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan
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54
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Tautz L, Bruckner S, Sareth S, Alonso A, Bogetz J, Bottini N, Pellecchia M, Mustelin T. Inhibition of Yersinia tyrosine phosphatase by furanyl salicylate compounds. J Biol Chem 2004; 280:9400-8. [PMID: 15615724 DOI: 10.1074/jbc.m413122200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To avoid detection and targeting by the immune system, the plague-causing bacterium Yersinia pestis uses a type III secretion system to deliver a set of inhibitory proteins into the cytoplasm of immune cells. One of these proteins is an exceptionally active tyrosine phosphatase termed YopH, which paralyzes lymphocytes and macrophages by dephosphorylating critical tyrosine kinases and signal transduction molecules. Because Y. pestis strains lacking YopH are avirulent, we set out to develop small molecule inhibitors for YopH. We used a novel and cost-effective approach, in which leads from a chemical library screening were analyzed and computationally docked into the crystal structure of YopH. This resulted in the identification of a series of novel YopH inhibitors with nanomolar Ki values, as well as the structural basis for inhibition. Our inhibitors lack the polar phosphate-mimicking moiety of rationally designed tyrosine phosphatase inhibitors, and they readily entered live cells and rescued them from YopH-induced tyrosine dephosphorylation, signaling paralysis, and cell death. These inhibitors may become useful for treating the lethal infection by Y. pestis.
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Affiliation(s)
- Lutz Tautz
- Infectious and Inflammatory Disease Center, The Burnham Institute, La Jolla, California 92037, USA
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55
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Alonso A, Narisawa S, Bogetz J, Tautz L, Hadzic R, Huynh H, Williams S, Gjörloff-Wingren A, Bremer MCD, Holsinger LJ, Millan JL, Mustelin T. VHY, a Novel Myristoylated Testis-restricted Dual Specificity Protein Phosphatase Related to VHX. J Biol Chem 2004; 279:32586-91. [PMID: 15138252 DOI: 10.1074/jbc.m403442200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The human DUSP15 gene encodes an uncharacterized 235-amino acid member of the subfamily of small dual specificity protein phosphatases related to the Vaccinia virus VH1 phosphatase. Similar to VHR-related MKPX (VHX) (DUSP22), the predicted protein has an N-terminal myristoylation recognition sequence, and we show here that both are indeed modified by the attachment of a myristate to Gly-2. In recognition of this relatedness to VHX, we refer to the DUSP15-encoded protein as VH1-related member Y (VHY). We report that VHY is expressed at high levels in the testis and barely detectable levels in the brain, spinal cord, and thyroid. A VHY-specific antiserum detected a protein with an apparent molecular mass of 26 kDa, and histochemical analysis showed that VHY was readily detectable in pachytene spermatocytes (midstage of meiotic division I) and round spermatids and weakly in Leydig cells (somatic cells outside of the seminiferous tubules). When expressed in 293T or NIH-3T3 cells, VHY was concentrated at the plasma membrane with some staining of vesicular structures in the Golgi region. Mutation of the myristoylation site Gly-2 abrogated membrane location. Finally, we demonstrate that VHY is an active phosphatase in vitro. We conclude that VHY is a new member of a subgroup of myristoylated VH1-like small dual specificity phosphatases.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Binding Sites
- Blotting, Northern
- Blotting, Southern
- Cell Line
- Cell Line, Tumor
- Cell Membrane/metabolism
- Cytoplasm/metabolism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- Dual-Specificity Phosphatases
- Embryo, Mammalian/metabolism
- Fibroblasts/metabolism
- Glutathione Transferase/metabolism
- Glycine/chemistry
- Golgi Apparatus/metabolism
- Humans
- Immunoblotting
- Immunohistochemistry
- JNK Mitogen-Activated Protein Kinases
- MAP Kinase Kinase 4
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Confocal
- Microscopy, Fluorescence
- Mitogen-Activated Protein Kinase Kinases/metabolism
- Mitogen-Activated Protein Kinase Phosphatases
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Myristic Acids/chemistry
- NIH 3T3 Cells
- Nitrophenols/chemistry
- Organophosphorus Compounds/chemistry
- Phosphoprotein Phosphatases/chemistry
- Phosphoric Monoester Hydrolases/metabolism
- Protein Structure, Tertiary
- Protein Tyrosine Phosphatases/chemistry
- Protein Tyrosine Phosphatases/metabolism
- RNA, Messenger/metabolism
- Repressor Proteins/chemistry
- Repressor Proteins/metabolism
- Sequence Homology, Amino Acid
- Spermatids/metabolism
- Testis/metabolism
- Transfection
- Vaccinia virus/metabolism
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Affiliation(s)
- Andres Alonso
- Program of Signal Transduction, Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA
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56
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Mustelin T, Alonso A, Bottini N, Huynh H, Rahmouni S, Nika K, Louis-dit-Sully C, Tautz L, Togo SH, Bruckner S, Mena-Duran AV, al-Khouri AM. Protein tyrosine phosphatases in T cell physiology. Mol Immunol 2004; 41:687-700. [PMID: 15220004 DOI: 10.1016/j.molimm.2004.04.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The molecular mechanisms of signal transduction have been the focus of intense research during the last decade. In T cells, much of the work has centered on protein tyrosine kinase-mediated signaling from the TCR and cytokine receptors, while the study of protein tyrosine phosphatases has lagged behind. Nevertheless, it has now become clear that many protein tyrosine phosphatases play equally important roles in T cell physiology and that no kinase-regulated system would work without the counterbalancing participation of phosphatases. In fact, we have learned that many processes are regulated primarily on the phosphatase side. This minireview summarizes the current state-of-the art in our understanding of the regulation and biology of protein tyrosine phosphatases in T lymphocyte physiology.
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Affiliation(s)
- Tomas Mustelin
- Program of Signal Transduction, Cancer Research Center, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
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57
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Alonso A, Burkhalter S, Sasin J, Tautz L, Bogetz J, Huynh H, Bremer MCD, Holsinger LJ, Godzik A, Mustelin T. The minimal essential core of a cysteine-based protein-tyrosine phosphatase revealed by a novel 16-kDa VH1-like phosphatase, VHZ. J Biol Chem 2004; 279:35768-74. [PMID: 15201283 DOI: 10.1074/jbc.m403412200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The smallest active protein-tyrosine phosphatase yet (only 16 kDa) is described here and given the name VHZ for VH1-like member Z because it belongs to the group of small Vaccinia virus VH1-related dual specific phosphatases exemplified by VHR, VHX, and VHY. Human VHZ is remarkably well conserved through evolution as it has species orthologs in frogs, fish, fly, and Archaea. The gene for VHZ, which we designate as DUSP25, is located on human chromosome 1q23.1 and consists of only two coding exons. VHZ is broadly expressed in tissues and cells, including resting blood lymphocytes, Jurkat T cells, HL-60, and RAMOS. In transfected cells, VHZ was located in the cytosol and in other cells also in the nucleoli. Endogenous VHZ showed a similar but more granular distribution. We show that VHZ is an active phosphatase and analyze its structure by computer modeling, which shows that in comparison with the 185-amino acid residue VHR, the 150-residue VHZ is a shortened version of VHR and contains the minimal set of secondary structure elements conserved in all known phosphatases from this class. The surface charge distribution of VHZ differs from that of VHR and is therefore unlikely to dephosphorylate mitogen-activated protein kinases. The remarkably high degree of conservation of VHZ through evolution may indicate a role in some ancient and fundamental physiological process.
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Affiliation(s)
- Andres Alonso
- Program of Signal Transduction, The Burnham Institute, La Jolla, California 92037, USA
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58
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Abstract
The mitogen-activated protein kinase (MAPK) group of serine/threonine protein kinases mediates the response of cells to many extracellular stimuli such as cytokines and growth factors. These protein kinases include the extracellular signal-regulated protein kinases (ERK) and two stress-activated protein kinases (SAPK), the c-Jun N-terminal kinases (JNK), and the p38 MAPK. The enzymes are evolutionarily conserved and are activated by a common mechanism that involves a protein kinase cascade. Scaffold proteins have been proposed to interact with MAPK pathway components to create a functional signaling module and to control the specificity of signal transduction. Here we critically evaluate the evidence that supports a physiologically relevant role of MAPK scaffold proteins in mammals.
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Affiliation(s)
- Deborah K Morrison
- Regulation of Cell Growth Laboratory, NCI-Frederick, P.O. Box B, Frederick, Maryland 21702, USA.
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59
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Ouellet M, Barbeau B, Tremblay MJ. Protein tyrosyl phosphatases in T cell activation: implication for human immunodeficiency virus transcriptional activity. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 2004; 73:69-105. [PMID: 12882515 DOI: 10.1016/s0079-6603(03)01003-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The protein tyrosine phosphatases (PTPs) superfamily is a large group of enzymes showing a wide diversity of structure and biological functions. Their implication in the regulation of signal transduction processes is critical for homeostasis and efficient cellular activation. Disturbance of the delicate balance between protein tyrosine kinase and protein tyrosine phosphatase activities is at the heart of a large number of diseases. Control of cellular activation is especially important for human immunodeficiency virus type 1 (HIV-1) since this retrovirus requires activated T cells in order to replicate efficiently. Identification of PTPs implicated in signaling pathways leading to upregulation of HIV-1 gene transcription therefore contributes to the general understanding of cellular factors needed for strong HIV-1 replication and progression to AIDS. The use of bisperoxovanadium compounds as potent, specific, and highly purified PTP inhibitors releases HIV-1 from PTP control and strongly increases HIV-1 gene expression. These inhibitors can thus be used to study signal transduction mechanisms regulated by PTP activity that are important for HIV-1 replication and provide new and interesting therapeutic avenues for the efficient control of this debilitating retroviral infection.
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Affiliation(s)
- Michel Ouellet
- Centre de Recherche en Infectiologie, Hôpital CHUL, Centre Hospitalier Universitaire de Québec, Canada, G1V 4G2
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60
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Mustelin T, Taskén K. Positive and negative regulation of T-cell activation through kinases and phosphatases. Biochem J 2003; 371:15-27. [PMID: 12485116 PMCID: PMC1223257 DOI: 10.1042/bj20021637] [Citation(s) in RCA: 215] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2002] [Revised: 12/12/2002] [Accepted: 12/16/2002] [Indexed: 11/17/2022]
Abstract
The sequence of events in T-cell antigen receptor (TCR) signalling leading to T-cell activation involves regulation of a number of protein tyrosine kinases (PTKs) and the phosphorylation status of many of their substrates. Proximal signalling pathways involve PTKs of the Src, Syk, Csk and Tec families, adapter proteins and effector enzymes in a highly organized tyrosine-phosphorylation cascade. In intact cells, tyrosine phosphorylation is rapidly reversible and generally of a very low stoichiometry even under induced conditions due to the fact that the enzymes removing phosphate from tyrosine-phosphorylated substrates, the protein tyrosine phosphatases (PTPases), have a capacity that is several orders of magnitude higher than that of the PTKs. It follows that a relatively minor change in the PTK/PTPase balance can have a major impact on net tyrosine phosphorylation and thereby on activation and proliferation of T-cells. This review focuses on the involvement of PTKs and PTPases in positive and negative regulation of T-cell activation, the emerging theme of reciprocal regulation of each type of enzyme by the other, as well as regulation of phosphotyrosine turnover by Ser/Thr phosphorylation and regulation of localization of signal components.
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Affiliation(s)
- Tomas Mustelin
- Program of Signal Transduction, Cancer Center, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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61
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Abstract
The last decade has seen an exponentially increasing interest in the molecular mechanisms of signal transduction. In T cells, much of the focus has been on protein tyrosine kinase (PTK)-mediated signaling from the T cell receptor (TCR) and cytokine receptors, while the study of protein tyrosine phosphatases (PTPases) has lagged behind. However, recent discoveries have revealed that several PTPases play important roles in many different aspects of T cell physiology. We predict that the phosphatases will become a 'hot topic' in the field within the next few years. This review summarizes the current understanding of the regulation and biology of PTPases in T lymphocyte activation.
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Affiliation(s)
- Tomas Mustelin
- Program of Signal Transduction, Cancer Research Center, The Burnham Institute, La Jolla, CA 92037, USA.
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62
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Alonso A, Rahmouni S, Williams S, van Stipdonk M, Jaroszewski L, Godzik A, Abraham RT, Schoenberger SP, Mustelin T. Tyrosine phosphorylation of VHR phosphatase by ZAP-70. Nat Immunol 2003; 4:44-8. [PMID: 12447358 DOI: 10.1038/ni856] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2002] [Accepted: 10/01/2002] [Indexed: 11/09/2022]
Abstract
The ZAP-70 tyrosine kinase is a key component of the signaling machinery for the T cell antigen receptor (TCR). Whereas recruitment and activation of ZAP-70 are relatively well understood, the proteins phosphorylated by ZAP-70 are incompletely known. We report here that VHR, a Vaccinia virus VH1-related dual-specific protein phosphatase that inactivates the mitogen-activated kinases Erk2 and Jnk, is phosphorylated at Y138 by ZAP-70. Tyr138 phosphorylation was required for VHR to inhibit the Erk2-Elk-1 pathway and, conversely, the VHR(Y138F) mutant augmented TCR-induced Erk2 kinase and activation of the gene encoding interleukin 2. These results suggest that VHR is a target for ZAP-70 and tempers activation of the Erk2 pathway in a ZAP-70-controlled manner.
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Affiliation(s)
- Andres Alonso
- Program of Signal Transduction, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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63
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Hood KL, Tobin JF, Yoon C. Identification and characterization of two novel low-molecular-weight dual specificity phosphatases. Biochem Biophys Res Commun 2002; 298:545-51. [PMID: 12408986 DOI: 10.1016/s0006-291x(02)02488-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have cloned and characterized two novel human low molecular weight dual specificity phosphatases (LMW-DSPs). Both genes are expressed exclusively in the testis, but are not altered in any of several disease states examined. Transfection into COS cells indicates that both proteins are expressed in the nucleus and the cytoplasm. Both proteins are able to dephosphorylate the phosphotyrosine analog pNPP in vitro and can be inhibited by sodium orthovanadate. In vitro experiments also demonstrate that both DSPs can dephosphorylate single and diphosphorylated synthetic MAPK peptides, with preference for the phosphotyrosine and diphosphorylated forms over phosphothreonine. However, when co-transfected with MAPKs into COS cells, the novel DSPs exhibited no detectable in vivo activity against MAPKs under our conditions. Our data suggest that these novel LMW-DSPs might belong to a new subclass of testis-specific proteins that act independently of the MAPK signal transduction cascade and do not depend on N-terminal docking regions for substrate binding.
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Affiliation(s)
- Kristin L Hood
- Metabolic and Respiratory Diseases, Wyeth Research, T4007, 87 Cambridge Park Drive, Cambridge, MA 02140, USA
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64
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Chen AJ, Zhou G, Juan T, Colicos SM, Cannon JP, Cabriera-Hansen M, Meyer CF, Jurecic R, Copeland NG, Gilbert DJ, Jenkins NA, Fletcher F, Tan TH, Belmont JW. The dual specificity JKAP specifically activates the c-Jun N-terminal kinase pathway. J Biol Chem 2002; 277:36592-601. [PMID: 12138158 DOI: 10.1074/jbc.m200453200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The involvement of dual specificity phosphatases (DSPs) in the mitogen-activated protein kinase (MAPK) signaling has been mostly limited to the inactivation of MAPKs by the direct dephosphorylation of the TXY motif within their activation loop. We report the cloning and characterization of a murine DSP, called JNK pathway-associated phosphatase (JKAP), which lacks the regulatory region present in most other MAP kinase phosphatases (MKPs) and is preferentially expressed in murine Lin(-)Sca-1(+) stem cells. Overexpression of JKAP in human embryonic kidney 293T cells specifically activated c-Jun N-terminal kinase (JNK) but not p38 and extracellular signal-regulated kinase 2. Overexpression of a mutant JKAP, JKAP-C88S, blocked tumor necrosis factor-alpha-induced JNK activation. Targeted gene disruption in murine embryonic stem cells abolished JNK activation by tumor necrosis factor-alpha and transforming growth factor-beta, but not by ultraviolet-C irradiation, indicating that JKAP is necessary for optimal JNK activation. JKAP associated with JNK and MKK7, but not SEK1, in vivo. However, JKAP did not interact with JNK in vitro, suggesting that JKAP exerts its effect on JNK in an indirect manner. Taken together, these studies identify a positive regulator for the JNK pathway and suggest a novel role for DSP in mitogen-activated protein kinase regulation.
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Affiliation(s)
- Alice J Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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65
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Zama T, Aoki R, Kamimoto T, Inoue K, Ikeda Y, Hagiwara M. Scaffold role of a mitogen-activated protein kinase phosphatase, SKRP1, for the JNK signaling pathway. J Biol Chem 2002; 277:23919-26. [PMID: 11959862 DOI: 10.1074/jbc.m200838200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Stress-activated protein kinase (SAPK) pathway-regulating phosphatase 1 (SKRP1) has been identified as a member of the mitogen-activated protein kinase (MAPK) phosphatase (MKP) family that interacts physically with the MAPK kinase (MAPKK) MKK7, a c-Jun N-terminal kinase (JNK) activator, and inactivates the MAPK JNK pathway. Although these findings indicated that SKRP1 contributes to the precise regulation of JNK signaling, it remains to be elucidated how SKRP1 is integrated into this pathway. We report that SKRP1 also plays a scaffold role for the JNK signaling, judged by the following observations. SKRP1 selectively formed the stable complexes with MKK7 but not with MKK4 and biphasically regulated the MKK7 activity and MKK7-induced gene transcription in vivo. Co-precipitation analysis between SKRP1 and MKK7-activating MAPKK kinases (MAPKKKs) revealed that SKRP1 also interacted with the MAPKKK, apoptosis signal-regulating kinase 1 (ASK1), but not with MAP kinase kinase kinase 1 (MEKK1). Consistent with these findings, SKRP1 expression increased the ASK1-MKK7 complexes in a dose-dependent manner and specifically enhanced the activation of MKK7 by ASK1. Thus, our findings are, to our knowledge, the first evidence to show that an MKP also functions as a scaffold protein for the particular MAPK signaling.
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Affiliation(s)
- Takeru Zama
- Department of Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-0016, Japan
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66
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Zama T, Aoki R, Kamimoto T, Inoue K, Ikeda Y, Hagiwara M. A novel dual specificity phosphatase SKRP1 interacts with the MAPK kinase MKK7 and inactivates the JNK MAPK pathway. Implication for the precise regulation of the particular MAPK pathway. J Biol Chem 2002; 277:23909-18. [PMID: 11959861 DOI: 10.1074/jbc.m200837200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Mitogen-activated protein kinases (MAPKs) are activated in response to various extracellular stimuli, and their activities are regulated by upstream activating kinases and protein phosphatases such as MAPK phosphatases (MKPs). We report the identification and characterization of a novel MKP termed SKRP1 (SAPK pathway-regulating phosphatase 1). It contains an extended active site sequence motif conserved in all MKPs but lacks a Cdc25 homology domain. Immunoblotting analysis revealed that SKRP1 is constitutively expressed, and its transcripts of 4.0 and 1.0 kb were detected in almost tissues examined. SKRP1 was highly specific for c-Jun N-terminal kinase (JNK) in vitro and effectively suppressed the JNK activation in response to tumor necrosis factor alpha or thapsigargin. Endogenous SKRP1 was present predominantly in the cytoplasm and co-localized with JNK. However, SKRP1 does not bind directly to its target JNK, but co-precipitation of SKRP1 with the MAPK kinase MKK7, a JNK activator, was found in vitro and in vivo. Furthermore, we found that SKRP1 did not interfere with the co-precipitation of MKK7 with JNK. Together, our findings indicate that SKRP1 interacts with its physiological substrate JNK through MKK7, thereby leading to the precise regulation of JNK activity in vivo.
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Affiliation(s)
- Takeru Zama
- Department of Medicine, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-0016, Japan
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