Abstract
Proapoptotic nuclear receptor family member Nur77 translocates from the nucleus to the mitochondria, where it interacts with Bcl-2 to trigger apoptosis. Nur77 translocation is induced by certain apoptotic stimuli, including the synthetic retinoid-related 6-[3-(1-adamantyl)-4-hydroxyphenyl]-2-naphthalenecarboxylic acid (AHPN)/CD437 class. In this study, we investigated the molecular mechanism by which AHPN/CD437 analog (E)-4-[3-(1-adamantyl)-4-hydroxyphenyl]-3-chlorocinnamic acid (3-Cl-AHPC) induces Nur77 nuclear export. Our results demonstrate that 3-Cl-AHPC effectively activated Jun N-terminal kinase (JNK), which phosphorylates Nur77. Inhibition of JNK activation by a JNK inhibitor suppressed 3-Cl-AHPC-induced Nur77 nuclear export and apoptosis. In addition, several JNK upstream activators, including the phorbol ester TPA, anisomycin and MAPK kinase kinase-1 (MEKK1), phosphorylated Nur77 and induced its nuclear export. However, Nur77 phosphorylation by JNK, although essential, was not sufficient for inducing Nur77 nuclear export. Induction of Nur77 nuclear export by MEKK1 required a prolonged MEKK1 activation and was attenuated by Akt activation. Expression of constitutively active Akt prevented MEKK1-induced Nur77 nuclear export. Conversely, transfection of dominant-negative Akt or treatment with a phosphatidylinositol 3-kinase (PI3-K) inhibitor accelerated MEKK1-induced Nur77 nuclear export. Furthermore, mutation of an Akt phosphorylation residue Ser351 in Nur77 abolished the effect of Akt or the PI3-K inhibitor. Together, our results demonstrate that both activation of JNK and inhibition of Akt play a role in translocation of Nur77 from the nucleus to the cytoplasm.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Adamantane / analogs & derivatives*
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Adamantane / pharmacology
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Anisomycin / pharmacology
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Apoptosis / drug effects
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Cell Line, Tumor / drug effects
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Cell Line, Tumor / metabolism
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Cell Line, Tumor / ultrastructure
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Cell Nucleus / metabolism
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Cinnamates / pharmacology*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Enzyme Activation / drug effects
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Flavonoids / pharmacology
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Humans
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Imidazoles / pharmacology
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JNK Mitogen-Activated Protein Kinases / antagonists & inhibitors
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JNK Mitogen-Activated Protein Kinases / physiology*
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MAP Kinase Kinase 7 / genetics
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MAP Kinase Kinase 7 / pharmacology
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MAP Kinase Kinase Kinase 1 / physiology*
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Mutagenesis, Site-Directed
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Nuclear Receptor Subfamily 4, Group A, Member 1
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Phosphatidylinositol 3-Kinases / physiology
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Phosphoinositide-3 Kinase Inhibitors
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Phosphorylation / drug effects
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Protein Processing, Post-Translational* / drug effects
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Protein Transport / drug effects
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Proto-Oncogene Proteins c-akt / antagonists & inhibitors
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Proto-Oncogene Proteins c-akt / physiology*
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Proto-Oncogene Proteins c-bcl-2 / metabolism
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Pyridines / pharmacology
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Receptors, Cytoplasmic and Nuclear / genetics
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Receptors, Steroid / genetics
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Receptors, Steroid / metabolism*
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Recombinant Fusion Proteins / pharmacology
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Tetradecanoylphorbol Acetate / pharmacology
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Transcription Factors / genetics
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Transcription Factors / metabolism*
Substances
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4-(3-(1-adamantyl)-4-hydroxyphenyl)-3-chlorocinnamic acid
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Cinnamates
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DNA-Binding Proteins
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Flavonoids
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Imidazoles
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NR4A1 protein, human
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Nuclear Receptor Subfamily 4, Group A, Member 1
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Phosphoinositide-3 Kinase Inhibitors
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Proto-Oncogene Proteins c-bcl-2
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Pyridines
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Receptors, Cytoplasmic and Nuclear
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Receptors, Steroid
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Recombinant Fusion Proteins
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Transcription Factors
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Anisomycin
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AKT1 protein, human
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Proto-Oncogene Proteins c-akt
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JNK Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinase 1
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MAP3K1 protein, human
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MAP Kinase Kinase 7
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MAP2K7 protein, human
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Tetradecanoylphorbol Acetate
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SB 203580
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Adamantane
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2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one