title: Serine-threonine kinase receptor-associated protein inhibits apoptosis signal-regulating kinase 1 function through direct interaction.
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.
authors.affiliation: Department of Biochemistry, Biotechnology Research Institute, School of Life Sciences, Chungbuk National University, Cheongju 361-763, Korea.
authors.forename: Haiyoung
authors.initials: H
authors.lastname: Jung
authors.forename: Hyun-A
authors.initials: HA
authors.lastname: Seong
authors.forename: Ravi
authors.initials: R
authors.lastname: Manoharan
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Ha
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D048371:MAP Kinase Kinase 3 / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008565:Membrane Proteins; D051379:Mice; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D016601:RNA-Binding Proteins; D018808:Transcription Factor AP-1 / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D048948:14-3-3 Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000081382:Pyruvate Dehydrogenase Acetyl-Transferring Kinase; D016601:RNA-Binding Proteins; C403447:STRAP protein, human; D018808:Transcription Factor AP-1; C494631:VAC14 protein, human; D010769:Phosphothreonine; D010768:Phosphoserine; D006861:Hydrogen Peroxide; D017346:Protein Serine-Threonine Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482858:MAP3K5 protein, human; D048371:MAP Kinase Kinase 3; D053148:Caspase 3