title: Essential role of calcium in the regulation of MAP kinase phosphatase-1 expression.
abstract: Mitogen-activated protein (MAP) kinase phosphatase-1 (MKP-1) is a dual-specificity protein phosphatase encoded by an immediate-early gene responsive to growth factors and stress. The MKP-1 protein selectively inactivates MAP kinases in vitro by dephosphorylation of the regulatory Thr and Tyr residues. Little is known on the mechanisms that regulate MKP-1 gene expression. Here, we demonstrate that Ca2+ is both necessary and sufficient for the induction of MKP-1 gene expression. Treatment of Rat1 fibroblasts with the Ca2+ chelating agent BAPTA completely suppressed serum-induced MKP-1 expression in a dose- and time-dependent manner. The inhibitory effect of BAPTA was observed at the level of the protein and the mRNA. Importantly, Ca2+ chelation blocked the induction of MKP-1 expression in response to all stimuli tested and in different cell types. Increasing the intracellular concentration of Ca2+ with the ionophore A23187 was sufficient to induce MKP-1 mRNA and protein expression in rat fibroblasts. We also provide evidence that activation of MAP kinases is not an absolute requirement for induction of the MKP-1 gene. Exposure of rat fibroblasts to A23187 induced MKP-1 expression without activating the JNK and p38 MAP kinase pathways. Also, inhibition of the ERK pathway with the selective MEK inhibitor PD98059 did not interfere with serum-stimulated MKP-1 mRNA expression. These results will help define the regulatory mechanisms that govern MKP-1 gene transcription in target cells.
authors.affiliation: Centre de Recherche, Hôtel-Dieu de Montréal and Department of Pharmacology, University of Montreal, Quebec, Canada.
authors.forename: J C
authors.initials: JC
authors.lastname: Scimeca
authors.forename: M J
authors.initials: MJ
authors.lastname: Servant
authors.forename: J O
authors.initials: JO
authors.lastname: Dyer
authors.forename: S
authors.initials: S
authors.lastname: Meloche
mesh_terms: D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D054638:Dual Specificity Phosphatase 1; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism*; D007476:Ionophores / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D010749:Phosphoprotein Phosphatases; D011494:Protein Kinases / Q000378:metabolism; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D017874:Immediate-Early Proteins; D007476:Ionophores; D009419:Nerve Tissue Proteins; D011506:Proteins; D012333:RNA, Messenger; D000001:Calcimycin; D004533:Egtazic Acid; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D054638:Dual Specificity Phosphatase 1; C517021:Dusp1 protein, rat; D017027:Protein Tyrosine Phosphatases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium