The growth factor-inducible immediate-early gene 3CH134 encodes a protein-tyrosine-phosphatase.

Abstract

Stimulation of fibroblasts with serum growth factors results in the rapid activation ofa set of immediate-early genes, among them 3CH134. We have purified a bacterially expressed form of the 3CH134-encoded polypeptide and demonstrated that it has intrinsic protein-tyrosine-phosphatase (PTPase; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) activity in vitro. This activity is optimal at pH 7.5, is sensitive to vanadate and cysteinyl modifying agents, and is insensitive to a panel of serine/threonine phosphatase inhibitors. Purified 3CH134 protein displays a high degree of selectivity among the tyrosine-phosphorylated polypeptide substrates tested. Under our assay conditions, the rates of dephosphorylation are in the order EDNDYINASL peptide < myelin basic protein < reduced, carboxyamidomethylated, and maleylated lysozyme (RCML) < p42m%*. There is a 200-fold range in rates for these substrates, with p42maPac dephosphorylated 15-fold more rapidly than RCML. Although 3CH134 is most closely related to the tyrosine/serine dual-speciffcity phosphatase VH1, we failed to detect any 3CH134-directed activity on casein or RCML phosphorylated on serine/threonine residues by cAMP-dependent protein kinase. Since 3CH134 expression is controlled transcriptionally and posttranscriptionally, it may represent a class of PTPases whose activity is regulated at the level of protein synthesis and degradation.Serum growth factors stimulate cell proliferation through interactions with their specific cell-surface receptors, activating the intrinsic receptor protein-tyrosine kinases (PTKs; ATP: protein-tyrosine O-phosphotransferase, EC 2.7.1.112). This leads to signal transduction events that include reversible phosphorylation of a number of cellular substrates on tyrosyl residues. Some of these signals are transmitted to the nucleus, where the activation of a set of immediate-early genes occurs. These immediate-early genes encode a diverse array of regulatory proteins including transcription factors and cytokines (1-3). Their expression has been hypothesized to mediate the biological effects of the stimulatory growthfactor.An important feature of these phosphorylation events is their reversibility. The actions of PTKs in conjunction with the activity of a family of protein-tyrosine-phosphatases (PTPases; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) control the phosphorylation state of tyrosyl residues in signaling proteins. The PTPases include transmembrane, receptor-like, and cytoplasmic enzymes defined by a unique sequence motif, (I/V)HCXAGXXR(S/T)G (4). We have noted that this motif, which contains a cysteinyl residue essential for activity, is present in the predicted sequence of the protein product encoded by the immediateearly gene 3CH134 (5).The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.3CH134 is activated rapidly and transiently in quiesce...

A novel human ERK phosphatase regulates H-ras and v-raf signal transduction

“…These results are consistent with published reports of ERK dephosphorylation in vitro by CL100 and 3CH134 (Alessi et al, 1993;Zheng and Guan, 1993;Charles et al, 1993), PAC1 (Ward et al, 1994) and B23 (Ishibashi et al, 1994) and by 3CH134 and PAC1 (Chu et al, 1996) expressed transiently in COS cells. Using a simple mixture of puri®ed bacterially expressed recombinant proteins, we found previously that puri®ed VHR protein could dephosphorylate ERK1 protein in vitro (Ishibashi et al, 1994).…”

“…Many of these dual-speci®city PTPs (dsPTPs) have been implicated in the regulation of cell proliferation: cdc25 dephosphorylates and activates the cdc2 kinase, stimulating mitosis (Dunphy and Kumagai, 1991;Gautier et al, 1991;Millar et al, 1991); KAP/cdil interacts with the cyclin-dependent kinases CDK2 and cdc2 (Hannon et al, 1994;Gyuris et al, 1995); and disruption of the yeast VH1 gene results in growth retardation (Guan et al, 1992). Also among the dsPTPs are CL100 (Alessi et al, 1993), its mouse homolog 3CH134 (known also as MKP-1; Charles et al, 1992Charles et al, , 1993, PAC-1 (Rohan et al, 1993) and B23 (Ishibashi et al, 1994) that preferentially dephosphorylate and inactivate extracellular signal-regulated kinase (ERK), a kinase that is activated by phosphorylation on both threonine and tyrosine residues in a TXY motif by ERK kinase, or MEK (reviewed in Marshall, 1995). The fact that ERK, MEK, and related kinases such as stressactivated protein kinase (SAPK) and the product of the yeast high osmolarity glycerol response gene-1 (p38 HOG1) mediate mitogenesis, di erentiation, and cellular responses to stress (reviewed in Cano and Mahadevan, 1995;Davis, 1994;Cobb and Goldsmith, 1995) suggests that their regulatory dsPTPs also function in these pathways.…”

RK‐682, a potent inhibitor of tyrosine phosphatase, arrested the mammalian cell cycle progression at G1phase

“…Dual-specificity phosphatases, for example, cdc25, HVH1 and 3CH134 are known to be involved in cell cycle progression [3], MAP kinase inactivation [18] and growth factor stimulation [19], respectively. The specific inhibitor of the dual-specificity phosphatase will be a valuable tool to reveal the signal transduction.…”

The MAPK/ERK Cascade Targets Both Elk-1 and cAMP Response Element-Binding Protein to Control Long-Term Potentiation-Dependent Gene Expression in the Dentate GyrusIn Vivo

“…To address this issue, we examined the expression of MKP-1, described in cell lines in vitro as an IEG that is rapidly transcribed by mitogens and translated to inactivate MAPK/ERK (Charles et al, 1993;Sun et al, 1993). Using in situ hybridization, we tested whether MKP-1 mRNA could be upregulated after the induction of LTP.…”