Abstract
Interferon-γ (IFN-γ) engenders strong antiproliferative responses, in part through activation of p53. However, the long-known IFN-γ-dependent upregulation of human Trp-tRNA synthetase (TrpRS), a cytoplasmic enzyme that activates tryptophan to form Trp-AMP in the first step of protein synthesis, is unexplained. Here we report a nuclear complex of TrpRS with the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) and with poly(ADP-ribose) polymerase 1 (PARP-1), the major PARP in human cells. The IFN-γ-dependent poly(ADP-ribosyl)ation of DNA-PKcs (which activates its kinase function) and concomitant activation of the tumor suppressor p53 were specifically prevented by Trp-SA, an analog of Trp-AMP that disrupted the TrpRS-DNA-PKcs-PARP-1 complex. The connection of TrpRS to p53 signaling in vivo was confirmed in a vertebrate system. These and further results suggest an unexpected evolutionary expansion of the protein synthesis apparatus to a nuclear role that links major signaling pathways.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Catalytic Domain
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Cell Culture Techniques
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Cell Nucleus / drug effects
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Cell Nucleus / enzymology
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Cell Nucleus / metabolism
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Cytoplasm / drug effects
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Cytoplasm / enzymology
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Cytoplasm / metabolism
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DNA-Activated Protein Kinase / genetics
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DNA-Activated Protein Kinase / metabolism*
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Electrophoresis, Polyacrylamide Gel
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Embryo, Nonmammalian / enzymology
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HeLa Cells
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Humans
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Immunoprecipitation
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Interferon-gamma / pharmacology*
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Interferon-gamma / physiology
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Microscopy, Confocal
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Models, Molecular
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Phosphorylation
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Poly (ADP-Ribose) Polymerase-1
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Poly(ADP-ribose) Polymerases / genetics
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Poly(ADP-ribose) Polymerases / metabolism*
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Protein Interaction Maps
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Signal Transduction / drug effects*
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Transfection
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Tryptophan-tRNA Ligase / genetics
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Tryptophan-tRNA Ligase / metabolism*
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Tumor Suppressor Protein p53 / genetics
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Tumor Suppressor Protein p53 / metabolism*
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Zebrafish / embryology
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Zebrafish / metabolism
Substances
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Tumor Suppressor Protein p53
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Interferon-gamma
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PARP1 protein, human
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Poly (ADP-Ribose) Polymerase-1
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Poly(ADP-ribose) Polymerases
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DNA-Activated Protein Kinase
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Tryptophan-tRNA Ligase