Abstract
The nuclear constitutive active/androstane receptor (CAR) is inactivated and sequestered in the cytoplasm when Thr-38 is phosphorylated. Here, we have demonstrated that activated ERK1/2 interacts with phosphorylated CAR to repress dephosphorylation of Thr-38. The phosphorylation-dependent interaction between CAR and ERK1/2 was examined by co-immunoprecipitation experiments of ectopically expressed FLAG-tagged CAR T38A and CAR T38D mutants with endogenous phospho-ERK1/2 in Huh-7 cells. Phospho-ERK1/2 coprecipitated only the phosphorylation-mimicking CAR T38D mutant; this coprecipitation was mediated by the interaction with the xenochemical response signal peptide near the C terminus of CAR. This interaction increased after EGF treatment and decreased after treatment with the MEK inhibitor U0126 as well as after knockdown of MEK1/2 by shRNA in Huh-7 cells. The phosphorylation levels of Thr-38 of CAR decreased in U0126-treated Huh-7 cells. Thus, activated ERK1/2 interacts with CAR and represses dephosphorylation of Thr-38, providing a cell signal-regulated mechanism for CAR activation.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, N.I.H., Intramural
MeSH terms
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Amino Acid Substitution
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Animals
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Butadienes / pharmacology
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Cell Line
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Constitutive Androstane Receptor
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Cytoplasm / genetics
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Cytoplasm / metabolism*
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Enzyme Activation / drug effects
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Enzyme Activation / physiology
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Enzyme Inhibitors / pharmacology
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Humans
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MAP Kinase Kinase 1 / antagonists & inhibitors
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MAP Kinase Kinase 1 / genetics
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MAP Kinase Kinase 1 / metabolism
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MAP Kinase Kinase 2 / antagonists & inhibitors
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MAP Kinase Kinase 2 / genetics
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MAP Kinase Kinase 2 / metabolism
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Male
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Mice
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Mice, Inbred C3H
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Mitogen-Activated Protein Kinase 1 / genetics
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Mitogen-Activated Protein Kinase 1 / metabolism*
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Mitogen-Activated Protein Kinase 3 / genetics
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Mitogen-Activated Protein Kinase 3 / metabolism*
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Mutation, Missense
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Nitriles / pharmacology
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Phosphorylation / drug effects
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Phosphorylation / physiology
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Protein Sorting Signals / physiology
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Protein Structure, Tertiary
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Protein Transport / drug effects
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Protein Transport / physiology
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Receptors, Cytoplasmic and Nuclear / genetics
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Receptors, Cytoplasmic and Nuclear / metabolism*
Substances
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Butadienes
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Constitutive Androstane Receptor
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Enzyme Inhibitors
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NR1I3 protein, human
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Nitriles
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Nr1i3 protein, mouse
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Protein Sorting Signals
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Receptors, Cytoplasmic and Nuclear
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U 0126
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MAP2K2 protein, human
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MAPK1 protein, human
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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MAP Kinase Kinase 1
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MAP Kinase Kinase 2
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MAP2K1 protein, human
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Map2k1 protein, mouse
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Map2k2 protein, mouse