Abstract
Rat T lymphoblasts arrested in the G1 phase of the cell cycle by interleukin-2 (IL-2) deprivation can be forced to proceed to the S phase when they are stimulated with IL-2 or the phorbol ester phorbol 12,13-dibutyrate (PDBu). When PDBu is used as a stimulus, extracellular regulated kinase 2 (ERK2) is activated by threonine and tyrosine phosphorylation by the dual-specificity kinase MEK. Here we have studied the regulation of ERK2 dephosphorylation as a mechanism for inactivation of this kinase. In vivo inhibition of ERK2 dephosphorylation observed after preincubation with translation or transcription inhibitors (cycloheximide or actinomycin, respectively) indicates the involvement of at least one inducible phosphatase, the best candidate for which is the dual-specificity phosphatase PAC-1. Other noninducible phosphatases must act as well, however, because sodium orthovanadate is a more effective dephosphorylation blocker than cycloheximide. In addition, the okadaic acid effect in ERK2 dephosphorylation indicates that Ser/Thr phosphatases are also involved, directly and/or indirectly.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Cells, Cultured
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Cycloheximide / pharmacology
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Dactinomycin / pharmacology
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Dual Specificity Phosphatase 2
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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G1 Phase / drug effects*
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G1 Phase / physiology
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Indoles / pharmacology
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Maleimides / pharmacology
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Mitogen-Activated Protein Kinase 1
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Nucleic Acid Synthesis Inhibitors / pharmacology
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Okadaic Acid / pharmacology
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Phorbol 12,13-Dibutyrate / pharmacology
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Phosphoric Monoester Hydrolases / drug effects
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Phosphoric Monoester Hydrolases / metabolism
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Phosphorylation / drug effects
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Protein Kinase C / antagonists & inhibitors
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Protein Phosphatase 2
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Protein Synthesis Inhibitors / pharmacology
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Protein Tyrosine Phosphatases / drug effects
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Protein Tyrosine Phosphatases / genetics
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RNA, Messenger / drug effects
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Rats
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T-Lymphocytes / cytology
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T-Lymphocytes / drug effects*
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T-Lymphocytes / enzymology
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Vanadates / pharmacology
Substances
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Enzyme Inhibitors
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Indoles
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Maleimides
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Nucleic Acid Synthesis Inhibitors
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Protein Synthesis Inhibitors
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RNA, Messenger
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Dactinomycin
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Okadaic Acid
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Phorbol 12,13-Dibutyrate
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Vanadates
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Cycloheximide
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Protein Kinase C
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Calcium-Calmodulin-Dependent Protein Kinases
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Mitogen-Activated Protein Kinase 1
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Protein Phosphatase 2
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Phosphoric Monoester Hydrolases
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Dual Specificity Phosphatase 2
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Dusp2 protein, rat
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Protein Tyrosine Phosphatases
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bisindolylmaleimide I