Abstract
Serine-threonine kinase receptor-associated protein (STRAP) interacts with transforming growth factor beta (TGF-beta) receptors and inhibits TGF-beta signaling. Here, we identify STRAP as an interacting partner of ASK1 (apoptosis signal-regulating kinase 1). The association between ASK1 and STRAP is mediated through the C-terminal domain of ASK1 and the fourth and sixth WD40 repeats of STRAP. Using cysteine-to-serine amino acid substitution mutants of ASK1 (C1005S, C1351S, C1360S, and C1351S/C1360S) and STRAP (C152S, C270S, and C152S/C270S), we demonstrated that Cys(1351) and Cys(1360) of ASK1 and Cys(152) and Cys(270) of STRAP are required for ASK1-STRAP binding. ASK1 phosphorylated STRAP at Thr(175) and Ser(179), suggesting a potential role for STRAP phosphorylation in ASK1 activity regulation. Expression of wild-type STRAP, but not STRAP mutants (C152S/C270S and T175A/S179A), inhibited ASK1-mediated signaling to both JNK and p38 kinases by stabilizing complex formation between ASK1 and its negative regulators, thioredoxin and 14-3-3, or decreasing complex formation between ASK1 and its substrate MKK3. In addition, STRAP suppressed H(2)O(2)-mediated apoptosis in a dose-dependent manner by inhibiting ASK1 activity through direct interaction. These results suggest that STRAP can act as a negative regulator of ASK1.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / metabolism
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Animals
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Apoptosis / drug effects
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Caspase 3 / metabolism
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Cell Line
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Enzyme Activation / drug effects
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Humans
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Hydrogen Peroxide / pharmacology
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Intracellular Signaling Peptides and Proteins
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MAP Kinase Kinase 3 / metabolism
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MAP Kinase Kinase Kinase 5 / antagonists & inhibitors*
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MAP Kinase Kinase Kinase 5 / chemistry
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MAP Kinase Kinase Kinase 5 / metabolism
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MAP Kinase Signaling System / drug effects
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Membrane Proteins
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Mice
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Neoplasm Proteins / chemistry
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Neoplasm Proteins / metabolism*
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Phosphorylation / drug effects
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Phosphoserine / metabolism
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Phosphothreonine / metabolism
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Protein Binding / drug effects
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Protein Interaction Mapping
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Protein Serine-Threonine Kinases / metabolism
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Protein Structure, Tertiary
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Pyruvate Dehydrogenase Acetyl-Transferring Kinase
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RNA-Binding Proteins
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Transcription Factor AP-1 / genetics
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Transcription, Genetic / drug effects
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p38 Mitogen-Activated Protein Kinases / metabolism
Substances
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14-3-3 Proteins
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Intracellular Signaling Peptides and Proteins
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Membrane Proteins
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Neoplasm Proteins
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Pyruvate Dehydrogenase Acetyl-Transferring Kinase
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RNA-Binding Proteins
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STRAP protein, human
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Transcription Factor AP-1
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VAC14 protein, human
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Phosphothreonine
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Phosphoserine
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Hydrogen Peroxide
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Protein Serine-Threonine Kinases
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p38 Mitogen-Activated Protein Kinases
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MAP Kinase Kinase Kinase 5
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MAP3K5 protein, human
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MAP Kinase Kinase 3
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Caspase 3