title: Thioredoxin and TRAF family proteins regulate reactive oxygen species-dependent activation of ASK1 through reciprocal modulation of the N-terminal homophilic interaction of ASK1.
abstract: Apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein kinase kinase kinase family, plays pivotal roles in reactive oxygen species (ROS)-induced cellular responses. In resting cells, endogenous ASK1 constitutively forms a homo-oligomerized but still inactive high-molecular-mass complex including thioredoxin (Trx), which we designated the ASK1 signalosome. Upon ROS stimulation, the ASK1 signalosome unbinds from Trx and forms a fully activated higher-molecular-mass complex, in part by recruitment of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TRAF6. However, the precise mechanisms by which Trx inhibits and TRAF2 and TRAF6 activate ASK1 have not been elucidated fully. Here we demonstrate that the N-terminal homophilic interaction of ASK1 through the N-terminal coiled-coil domain is required for ROS-dependent activation of ASK1. Trx inhibited this interaction of ASK1, which was, however, enhanced by expression of TRAF2 or TRAF6 or by treatment of cells with H2O2. Furthermore, the H2O2-induced interaction was reduced by double knockdown of TRAF2 and TRAF6. These findings demonstrate that Trx, TRAF2, and TRAF6 regulate ASK1 activity by modulating N-terminal homophilic interaction of ASK1.
authors.affiliation: Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Fujino
authors.forename: Takuya
authors.initials: T
authors.lastname: Noguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Matsuzawa
authors.forename: Shota
authors.initials: S
authors.lastname: Yamauchi
authors.forename: Masao
authors.initials: M
authors.lastname: Saitoh
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Takeda
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ichijo
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048848:MAP Kinase Kinase Kinase 5 / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D050505:Mutant Proteins / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D017382:Reactive Oxygen Species / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D047992:TNF Receptor-Associated Factor 2 / Q000378:metabolism*; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D017382:Reactive Oxygen Species; D047992:TNF Receptor-Associated Factor 2; D048029:TNF Receptor-Associated Factor 6; D013879:Thioredoxins; D048848:MAP Kinase Kinase Kinase 5; C482859:Map3k5 protein, mouse