Although TAK1 signaling plays essential roles in eliciting cellular responses to interleukin-1 (IL-1), a proinflammatory cytokine, how the IL-1-TAK1 signaling pathway is positively and negatively regulated remains poorly understood. In this study, we investigated the possible role of a novel protein phosphatase 2C (PP2C) family member, PP2Cε, in the regulation of the IL-1-TAK1 signaling pathway. PP2Cε was composed of 303 amino acids, and the overall similarity of amino acid sequence between PP2Cε and PP2Cα was found to be 267. Ectopic expression of PP2Cε inhibited the IL-1- and TAK1-induced activation of mitogen-activated protein kinase kinase 4 (MKK4)-c-Jun N-terminal kinase or MKK3-p38 signaling pathway. PP2Cε dephosphorylated TAK1 in vitro. Co-immunoprecipitation experiments indicated that PP2Cε associates stably with TAK1 and attenuates the binding of TAK1 to MKK4 or MKK6. Ectopic expression of a phosphatase-negative mutant of PP2Cε, PP2Cε(D/A), which acted as a dominant negative form, enhanced both the association between TAK1 and MKK4 or MKK6 and the TAK1-induced activation of an AP-1 reporter gene. The association between PP2Cε and TAK1 was transiently suppressed by IL-1 treatment of the cells. Taken together, these results suggest that, in the absence of IL-1-induced signal, PP2Cε contributes to keeping the TAK1 signaling pathway in an inactive state by associating with and dephosphorylating TAK1.AY184801 Although TAK1 signaling plays essential roles in eliciting cellular responses to interleukin-1 (IL-1), a proinflammatory cytokine, how the IL-1-TAK1 signaling pathway is positively and negatively regulated remains poorly understood. In this study, we investigated the possible role of a novel protein phosphatase 2C (PP2C) family member, PP2Cε, in the regulation of the IL-1-TAK1 signaling pathway. PP2Cε was composed of 303 amino acids, and the overall similarity of amino acid sequence between PP2Cε and PP2Cα was found to be 267. Ectopic expression of PP2Cε inhibited the IL-1- and TAK1-induced activation of mitogen-activated protein kinase kinase 4 (MKK4)-c-Jun N-terminal kinase or MKK3-p38 signaling pathway. PP2Cε dephosphorylated TAK1 in vitro. Co-immunoprecipitation experiments indicated that PP2Cε associates stably with TAK1 and attenuates the binding of TAK1 to MKK4 or MKK6. Ectopic expression of a phosphatase-negative mutant of PP2Cε, PP2Cε(D/A), which acted as a dominant negative form, enhanced both the association between TAK1 and MKK4 or MKK6 and the TAK1-induced activation of an AP-1 reporter gene. The association between PP2Cε and TAK1 was transiently suppressed by IL-1 treatment of the cells. Taken together, these results suggest that, in the absence of IL-1-induced signal, PP2Cε contributes to keeping the TAK1 signaling pathway in an inactive state by associating with and dephosphorylating TAK1.AY184801 stress-activated protein kinase mitogen-activated protein kinase kinase PP2A, PP2B, and PP2C, protein phosphatase 1, 2A, 2B, and 2C, respectively interleukin hemagglutinin Jun N-terminal kinase cytomegalovirus glutathioneS-transferase maltose-binding protein Stress-activated protein kinases (SAPKs)1 are a subfamily of the mitogen-activated protein kinase superfamily and are highly conserved from yeast to mammalian cells. SAPKs relay signals in response to various extracellular stimuli, including environmental stress and inflammatory cytokines. In mammalian cells, two distinct classes of SAPKs have been identified, the c-Jun N-terminal kinases (JNK1, JNK2, and JNK3) and the p38 mitogen-activated protein kinases (p38α, p38ॆ, p38γ, and p38δ) (1Garrington T.P. Johnson G.L. Curr. Opin. Cell Biol. 1999; 11: 211-218Google Scholar, 2Ip Y.T. Davis R.J. Curr. Opin. Cell Biol. 1998; 10: 205-219Google Scholar). Activation of SAPKs requires phosphorylation of conserved tyrosine and threonine residues present in the catalytic domain. This phosphorylation is mediated by dual specificity protein kinases, which are members of the mitogen-activated protein kinase kinase (MKK) family. Of these, MKK3 and MKK6 phosphorylate p38, MKK7 phosphorylates JNK, and MKK4 can phosphorylate either. These MKKs, in turn, are similarly activated by the phosphorylation of conserved serine and threonine residues (1Garrington T.P. Johnson G.L. Curr. Opin. Cell Biol. 1999; 11: 211-218Google Scholar, 2Ip Y.T. Davis R.J. Curr. Opin. Cell Biol. 1998; 10: 205-219Google Scholar). Recently, several MKK-activating MKK kinases have been identified (3Widmann C. Gibson S. Jarpe M.B. Johnson G.L. Physiol. Rev. 1999; 79: 143-180Google Scholar). Some of these MKK kinases are also known to be activated by phosphorylation. In the absence of a signal, the constituents of the SAPK cascade return to their dephosphorylated, inactive state, suggesting an essential role for phosphatases in SAPK regulation. Protein phosphatases are classified into three groups, Ser/Thr phosphatases, Ser/Thr/Tyr phosphatases, and Tyr phosphatases, depending on their phosphoamino acid specificity. Dephosphorylation of SAPK signal pathway components requires the participation of a variety of phosphatases. In fact, participation by members of all three groups in the negative regulation of SAPK signaling pathways has been reported (4Tamura S. Hanada M. Ohnishi M. Katsura K. Sasaki M. Kobayashi T. Eur. J. Biochem. 2002; 269: 1060-1066Google Scholar). PP2C is one of four major protein serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) found in eukaryotes. At least six distinct PP2C gene products (2Cα, 2Cॆ, 2Cγ, 2Cδ, Wip1, and Ca2+/calmodulin-dependent protein kinase phosphatase) have been found in mammalian cells (5Tamura S. Lynch K.R. Larner J. Fox J. Yasui A. Kikuchi K. Suzuki Y. Tsuiki S. Proc. Natl. Acad. Sci. U. S. A. 1989; 86: 1796-1800Google Scholar, 6Wenk J. Trompeter H.I. Pettrich K.G. Cohen P.T.W. Campbell D.G. Mieskes G. FEBS Lett. 1992; 297: 135-138Google Scholar, 7Travis S.M. Welsh M.J. FEBS Lett. 1997; 412: 415-419Google Scholar, 8Guthridge M.A. Bellosta P. Tavoloni N. Basilico C. Mol. Cell. Biol. 1997; 17: 5485-5498Google Scholar, 9Tong Y. Quirion R. Shen S-H. J. Biol. Chem. 1998; 273: 35282-35290Google Scholar, 10Fiscella M. Zhang H. Fan S. Sakaguchi K. Shen S. Mercer W.E. Vande Woude G.F. O'Connor P.M. Appella E. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 6048-6053Google Scholar, 11Kitani T. Ishida A. Okuno S. Takeuchi M. Kameshita I. Fujisawa H. J. Biochem. (Tokyo). 1999; 125: 1022-1028Google Scholar, 12Leung-Hagesteijn C. Mahendra A. Naruszewicz I. Hannigan G.E. EMBO J. 2001; 20: 2160-2170Google Scholar). In addition, two distinct isoforms of the human PP2Cα (α-1 and -2) and five isoforms of the mouse PP2Cॆ (ॆ-1, -2, -3, -4, and -5) have been identified (13Mann D.J. Campbell D.G. McGowan C.H. Cohen P.T. Biochim. Biophys. Acta. 1992; 1130: 100-104Google Scholar, 14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar, 15Terasawa T. Kobayashi T. Murakami T. Ohnishi M. Kato S. Tanaka O. Kondo H. Yamamoto H. Takeuchi T. Tamura S. Arch. Biochem. Biophys. 1993; 307: 342-349Google Scholar, 16Kato S. Terasawa T. Kobayashi T. Ohnishi M. Sasahara Y. Kusuda K. Yanagawa Y. Hiraga A. Matsui Y. Tamura S. Arch. Biochem. Biophys. 1995; 318: 387-393Google Scholar). These isoforms are generated as splicing variants of a single pre-mRNA. Of the six different members of the PP2C family, three (PP2Cα, PP2Cॆ, and Wip1) have recently been implicated in the negative regulation of SAPK signaling pathways (14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar,17Hanada M. Kobayashi T. Ohnishi M. Ikeda S. Wang H. Katsura K. Yanagawa Y. Hiraga A. Kanamaru R. Tamura S. FEBS Lett. 1998; 437: 172-176Google Scholar, 18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar, 19Takekawa M. Adachi M. Nakahata A. Nakayama I. Itoh F. Tsukuda H. Taya Y. Imai K. EMB0 J. 2000; 19: 6517-6526Google Scholar). We and others have reported that ectopic expression of mouse PP2Cα or PP2Cॆ-1 inhibited the stress-activated MKK3/6-p38 and MKK4/7-JNK pathways but not the mitogen-activated MKK1-ERK1 pathway (14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar, 17Hanada M. Kobayashi T. Ohnishi M. Ikeda S. Wang H. Katsura K. Yanagawa Y. Hiraga A. Kanamaru R. Tamura S. FEBS Lett. 1998; 437: 172-176Google Scholar). Thus, negative regulation by PP2Cα and PP2Cॆ-1 is selective for SAPK pathways. We have provided further evidence indicating that PP2Cॆ-1 associates with another upstream kinase, TAK1, and inhibits the SAPK signaling pathways by direct dephosphorylation of TAK1 (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar). Takekawa et al. (14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar) have found that PP2Cα-2 dephosphorylates and inactivates MKK4, MKK6 and p38, both in vivo and in vitro. In addition, they reported that Wip1, whose expression is induced by ionizing radiation in a p53-dependent inactivates p38 by dephosphorylation of a conserved threonine and activation M. Zhang H. Fan S. Sakaguchi K. Shen S. Mercer W.E. Vande Woude G.F. O'Connor P.M. Appella E. Proc. Natl. Acad. Sci. U. S. A. 1997; 94: 6048-6053Google Scholar, 19Takekawa M. Adachi M. Nakahata A. Nakayama I. Itoh F. Tsukuda H. Taya Y. Imai K. EMB0 J. 2000; 19: 6517-6526Google Scholar). TAK1 was identified as a MKK kinase that in the signaling pathway K. K. H. K. I. N. T. E. Matsumoto K. 1995; Scholar). TAK1 can both the and pathways (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar). of the of activation of TAK1 have that a as an TAK1 H. K. K. A. Y. N. K. E. Matsumoto K. Scholar, K. Matsumoto K. Ninomiya-Tsuji J. J. Biol. Chem. 2000; Scholar). have indicated that TAK1 is also activated by various stimuli, including environmental stress and inflammatory and and another TAK1 binding has been found to TAK1 and and as a of TAK1 in the IL-1-induced signaling pathway K. K. H. K. S. T. Y. Matsumoto K. E. J. Biol. Chem. 1997; Scholar, G. S. A. K. H. K. Ninomiya-Tsuji J. Matsumoto K. Mol. Cell. 2000; Scholar). the of and negative regulation of TAK1 is not understood. In this study, we present evidence that a novel of the PP2C family in the negative regulation of the TAK1 signaling pathway and suggest that PP2Cε is in the IL-1-induced regulation of and for from protein and from was from The and by and from and human from and from Cell and from was from from We the sequence for the amino acid of the conserved in mouse PP2C family different a novel of the PP2C family, These three be and be of was by and of the from the of as the sequence for the are in the the This sequence has been the and all with to the sequence identified PP2C, TAK1, mitogen-activated protein kinases, and in mammalian cells these the of the to the generated by expression of the into or into to or maltose-binding protein expression as K. Matsumoto K. Ninomiya-Tsuji J. J. Biol. Chem. 2000; Scholar, K. Kobayashi T. Ikeda S. Ohnishi M. N. Yanagawa Y. R. T. S. Hiraga A. Tamura S. Biochem. J. 1998; Scholar). to the of PP2Cε cells and Scholar) cells in with and At the cells by the or The of for was and the cells for and was by protein kinase and as S. Kikuchi K. Hiraga A. M. Tsuiki S. Biochim. Biophys. Acta. Scholar, C.H. Cohen P. Scholar). The catalytic of protein kinase was as by and Scholar). The was by and the was TAK1, cells with of and of the The the and the was with and protein the with and and with in kinase and for The the TAK1 was with and with phosphatase and In to the JNK, of was into cells IL-1 was to the the and the cells for The cells in a and and the with and protein The was with and with the kinase and in In to the and into cells. The cells the and the was from the with The was with and and phosphatase was by the of from as S. Kikuchi K. Hiraga A. M. Tsuiki S. Biochim. Biophys. Acta. Scholar). TAK1 phosphatase was by the TAK1 with the indicated of or in phosphatase for The was by the of and the was to by the phosphatase the was with the indicated of with and in the kinase The for The by The by and by In to the MKK4 phosphatase the was with the for in phosphatase The in the by and with and with the indicated expression with and with was with the indicated and protein The to and The with the 4 with for and by as the was from the mouse with The was in a and a and was as T. Kobayashi T. Murakami T. Ohnishi M. Kato S. Tanaka O. Kondo H. Yamamoto H. Takeuchi T. Tamura S. Arch. Biochem. Biophys. 1993; 307: 342-349Google Scholar). the sequence of the PP2Cε was for the reporter gene was as (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar, J. J. Biol. Chem. 1999; Scholar). The reporter gene was to was with a reporter the of a was to the The a single of The and the and the was in the of the sequence and the in is M. Cell. Scholar). we an in of the to which was the The of the in was This that of the protein from the which is composed of 303 amino The of the be the products of the we that the between and The sequence six conserved in PP2C family members in to a amino acid to this protein A. P. Johnson T. Mol. Biol. Cell. 1995; Scholar). This that the protein was a novel PP2C family member, and was the between PP2Cα and PP2Cε was 267. the PP2Cε protein phosphatase or and with The protein or and protein phosphatase not The of was to that of was as the not was on mouse to the of PP2Cε signal of was in the and a signal to the was also found in the a signal of was in the Although the PP2Cε signal was not in or by we to the PP2Cε signal in these by suggesting that PP2Cε is in a variety of not distinct PP2C family members (PP2Cα, PP2Cॆ, and Wip1) have been implicated in the regulation of the SAPK (14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar, 17Hanada M. Kobayashi T. Ohnishi M. Ikeda S. Wang H. Katsura K. Yanagawa Y. Hiraga A. Kanamaru R. Tamura S. FEBS Lett. 1998; 437: 172-176Google Scholar, 18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar, 19Takekawa M. Adachi M. Nakahata A. Nakayama I. Itoh F. Tsukuda H. Taya Y. Imai K. EMB0 J. 2000; 19: 6517-6526Google Scholar). we the that PP2Cε was also in the regulation of SAPK signaling pathways. In cells, IL-1 the of the AP-1 the activation of TAK1 and J. K. A. Matsumoto K. 1999; Scholar). We cells, which the IL-1 with the expression of PP2Cε and the AP-1 an reporter gene to reported with PP2Cॆ-1 (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google PP2Cε inhibited the IL-1-induced activation of AP-1 in a We the TAK1-induced activation of AP-1 is also by the of PP2Cε The expression of TAK1 in cells activated the AP-1 reporter gene. This enhanced was suppressed by PP2Cε, suggesting that TAK1 or a that of TAK1 is a of TAK1 both and p38 signaling pathways and we also TAK1-induced activation of or p38 was suppressed by We or with in cells and the of PP2Cε on the activation of and PP2Cε was found to the activation of or These results indicated that a signaling between TAK1 and be a of We activation of p38 is by PP2Cε in cells. The expression of PP2Cα suppressed the phosphorylation of p38 in cells cells M. Kobayashi T. Ohnishi M. Ikeda S. Wang H. Katsura K. Yanagawa Y. Hiraga A. Kanamaru R. Tamura S. FEBS Lett. 1998; 437: 172-176Google Scholar). In PP2Cε in the cells on the phosphorylation of p38 suggesting direct on MKK3 and the that TAK1, which upstream of be the of TAK1 is a of PP2Cε, we the dephosphorylation of TAK1 with PP2Cε in and in cells, and was from with the TAK1 was with TAK1 The the TAK1 was and with or TAK1 was dephosphorylated by PP2Cॆ-1 (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar). was dephosphorylated by in a We PP2Cε MKK4 or and MKK4 or was with of PP2Cε in vitro. PP2Cε not MKK4 or the to on these we that PP2Cε TAK1 signaling pathways by dephosphorylating TAK1 the of PP2Cε on TAK1 in we for a dominant negative of PP2Cε in various of PP2Cε, in protein phosphatase We expression for five different of PP2Cε, in which of five different amino acids, known to be conserved in PP2C family members and to essential roles in the was by another amino We found that three of the In addition, one of these PP2Cε(D/A), in which been by was to the dephosphorylation of TAK1 by PP2Cε in PP2Cε(D/A), in cells, the of the AP-1 reporter gene by the PP2Cε expression of in cells enhanced further the AP-1 reporter gene These results the that as a dominant negative and that the PP2Cε in in the negative regulation of the SAPK signaling pathways. TAK1 was found to be a of PP2Cε, we the phosphatase was to with this we and or in cells The with was by The results that both PP2Cε and with TAK1 We the that PP2Cε with the TAK1, the of The in which is by is in both phosphorylation and activation K. Matsumoto K. Ninomiya-Tsuji J. J. Biol. Chem. 2000; Scholar). We and or in cells and the or by from the that, to TAK1, was with PP2Cε, indicating that phosphorylation of TAK1 is not for the association of TAK1 with PP2Cε PP2Cε associates with TAK1 also in we in cells and with The to protein was with or The with PP2Cε and to with TAK1 in vitro. We in the of the of signal between TAK1 and MKK4 or MKK6 by this we investigated the of PP2Cε or on the between TAK1 and MKK4 or MKK6. with or was in cells, and the or was of the with that TAK1 was with both MKK4 and MKK6 this association was enhanced by the of was by These results the that the association of TAK1 with association with MKK4 or MKK6 by a composed of TAK1, PP2Cε(D/A), and MKK4 or a not found with PP2Cε of PP2Cε in the regulation of TAK1 signaling pathway. The activation of MKK4 or MKK6 by TAK1 requires a between TAK1 and MKK4 or MKK6. PP2Cε binding to TAK1 with this association and the activation of MKK4 and MKK6 and the The binding of PP2Cε to TAK1 is transiently inhibited by This the activation of TAK1 and association with In binding of to TAK1 the association of TAK1 with MKK4 or MKK6 and the TAK1 signaling this we with MKK4 or MKK6 in the of TAK1 in the cells. or was with in the or absence of of in cells. and was with and the with was with MKK4 or MKK6 TAK1 was in the cells, was in the absence of the These results indicated that a composed of TAK1, PP2Cε(D/A), and MKK4 or MKK6 was in these cells These results also suggest that enhanced the of the AP-1 reporter gene by the association between MKK4 and TAK1 The evidence that the PP2Cε in cells attenuates the association between TAK1 and MKK4 or MKK6 to that, in the absence of an signal, PP2Cε with TAK1 and to keeping in an inactive state by activation of TAK1 by an upstream signal, PP2Cε from TAK1, activation as as association with MKK4 or MKK6. this we IL-1 treatment of the cells the association of PP2Cε with We PP2Cε in cells and the of IL-1 treatment on the association between the TAK1 and the In the absence of PP2Cε in the cells was with the TAK1 and The between PP2Cε and TAK1 was the cells with IL-1 for and 4 and the was enhanced by treatment of the cells with IL-1 for and 4 and These results suggest that IL-1 treatment of PP2Cε from TAK1, and PP2Cε with TAK1 on in a IL-1 treatment of the cells for not the activation of the AP-1 reporter gene of the of PP2Cε not In the AP-1 reporter gene was enhanced the of IL-1 and this IL-1-induced activation of the AP-1 reporter gene was suppressed by of PP2Cε The evidence that a of the TAK1 with the PP2Cε IL-1 treatment of the cells for and the of the AP-1 reporter gene was the of the IL-1 treatment has been that the activation of TAK1 by IL-1 the of TAK1 to on K. Matsumoto K. Ninomiya-Tsuji J. J. Biol. Chem. 2000; Scholar). in and of of of TAK1 was in with the IL-1-induced of PP2Cε from TAK1, and this was PP2Cε with TAK1 These results the that IL-1-induced of PP2Cε contributes to the activation of We in the of PP2Cε was by IL-1 was in cells, and the was with and the IL-1 The protein phosphatase of the as the in the was between the and the of the IL-1 treatment the of the the of IL-1 treatment was that of the We to IL-1 activation of TAK1 by also the of PP2Cε from We found that of TAK1 and PP2Cε not suppressed by the of in cells not These results suggest that the of PP2Cε from TAK1 is induced by IL-1 treatment of the cells. SAPK are signaling composed of three of activated protein MKK kinase, and phosphorylation of these components is essential for the activation of the SAPK protein phosphatases be to roles in their regulation. evidence that a of protein phosphatases to three different protein phosphatase groups Ser/Thr/Tyr and Tyr phosphatase) in the regulation of SAPK (4Tamura S. Hanada M. Ohnishi M. Katsura K. Sasaki M. Kobayashi T. Eur. J. Biochem. 2002; 269: 1060-1066Google Scholar). We recently reported that PP2Cॆ-1 the SAPK signaling pathways by associating with and dephosphorylating TAK1 (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar). In this study, we a novel of the PP2C family and role in signaling pathways. PP2Cε is composed of 303 amino and the six conserved in all members of mammalian PP2C family A. P. Johnson T. Mol. Biol. Cell. 1995; Scholar). The PP2Cε and protein phosphatase We present several of evidence suggesting that PP2Cε negatively the TAK1 pathways by dephosphorylating TAK1 PP2Cε in cells inhibited the activation of and p38 and PP2Cε dephosphorylated TAK1 but on the phosphorylation of MKK4 or in PP2Cε in cells not MKK3 or p38 and but stably with TAK1 a dominant negative mutant of PP2Cε, PP2Cε(D/A), inhibited the dephosphorylation of TAK1 by and further enhanced the TAK1-induced activation of the AP-1 reporter gene Taken together, these are with the that PP2Cε signaling by associating with and dephosphorylating of the of of PP2Cε and that they on the association between TAK1 and MKK4 or MKK6 and Thus, the expression of enhanced the association between TAK1 and MKK4 or PP2Cε expression the was with MKK4 or MKK6 TAK1 was and These that the PP2Cε in cells associates with TAK1, and this association the binding of MKK4 or MKK6 to TAK1, a not TAK1 and the dephosphorylation of TAK1 by PP2Cε, TAK1 MKK4 or MKK6 in the absence of the mutant We have that the expression of TAK1 the phosphorylation of both and p38 and the TAK1 be activated and to MKK4 and MKK6. PP2Cε is in the cells, the PP2Cε be to with TAK1 and and the dephosphorylated TAK1 for MKK4 or MKK6 The evidence that the association of PP2Cε with TAK1 attenuates the binding of MKK4 or MKK6 to TAK1 the that the association between PP2Cε and TAK1 be regulated by an upstream in indicated that IL-1 treatment of cells for the association between TAK1 and PP2Cε IL-1 treatment for enhanced the These results suggest that PP2Cε contributes to the SAPK in an inactive state in the absence of IL-1-induced and the of PP2Cε from TAK1 IL-1 treatment to the activation of TAK1 and These results also suggest that PP2Cε with TAK1 the the TAK1 signaling pathways by dephosphorylation of TAK1 in a of the PP2Cε was not inhibited by the IL-1 treatment for suggesting that from TAK1 not the of In the phosphatase of the the of IL-1 treatment was that of the This of the PP2Cε also be in the of regulation of of protein phosphatases have been known to in the negative regulation of SAPK signaling pathways (4Tamura S. Hanada M. Ohnishi M. Katsura K. Sasaki M. Kobayashi T. Eur. J. Biochem. 2002; 269: 1060-1066Google Scholar). of these phosphatases have that they the SAPK by a Thus, their activation or expression is induced by SAPK signaling and in turn, negatively the SAPK by dephosphorylation (4Tamura S. Hanada M. Ohnishi M. Katsura K. Sasaki M. Kobayashi T. Eur. J. Biochem. 2002; 269: 1060-1066Google M. Adachi M. Nakahata A. Nakayama I. Itoh F. Tsukuda H. Taya Y. Imai K. EMB0 J. 2000; 19: 6517-6526Google Scholar, S. F. A. J. J. 2001; Scholar, F. K. P. J. Biol. Chem. 1997; Scholar, J. Biol. Chem. 1997; Scholar, M. A. C. M. C. U. S. 1998; Scholar, T. T. E. J. Biol. Chem. 1999; Scholar). the phosphatases have for the of the SAPK components and the by a (14Takekawa M. Maeda T. Saito H. EMBO J. 1998; 17: 4744-4752Google Scholar). In this study, we that PP2Cε both in on and of TAK1 signaling pathways by from and associating with TAK1, study, in fact, a novel for regulation of SAPK signaling pathways by protein phosphatases. We reported that PP2Cॆ-1 also the TAK1 signaling pathways by dephosphorylating TAK1 (18Hanada M. Ninomiya-Tsuji J. Komaki K. Ohnishi M. Katsura K. Kanamaru R. Matsumoto K. Tamura S. J. Biol. Chem. 2001; 276: 5753-5759Google Scholar). to PP2Cε, PP2Cॆ-1 stably with TAK1, and a dominant negative mutant of PP2Cॆ-1 further enhanced the AP-1 reporter gene TAK1 has been found to be activated by a variety of extracellular as and stress K. K. H. K. I. N. T. E. Matsumoto K. 1995; Scholar, K. K. H. K. S. T. Y. Matsumoto K. E. J. Biol. Chem. 1997; Scholar, J. G. H. H. Ninomiya-Tsuji J. Matsumoto K. N. Mol. Cell. Biol. 2002; kinase of TAK1 in the signaling pathways. This the that the signaling activated by and in TAK1 be negatively regulated by a different protein is to that PP2Cॆ-1 TAK1 activated by a distinct from both PP2Cε and PP2Cॆ-1 on TAK1 in the signaling pathway but with different are to the of the dual regulation of TAK1 by PP2Cॆ-1 and We are to for
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