title: Critical roles of threonine 187 phosphorylation in cellular stress-induced rapid and transient activation of transforming growth factor-beta-activated kinase 1 (TAK1) in a signaling complex containing TAK1-binding protein TAB1 and TAB2.
abstract: Transforming growth factor-beta-activated kinase 1 (TAK1) mitogen-activated protein kinase kinase kinase has been shown to be activated by cellular stresses including tumor necrosis factor-alpha (TNF-alpha). Here, we characterized the molecular mechanisms of cellular stress-induced TAK1 activation, focusing mainly on the phosphorylation of TAK1 at Thr-187 and Ser-192 in the activation loop. Thr-187 and Ser-192 are conserved among species from Caenorhabditis elegans to human, and their replacement with Ala resulted in inactivation of TAK1. Immunoblotting with a novel phospho-TAK1 antibody revealed that TNF-alpha significantly induced the phosphorylation of endogenous TAK1 at Thr-187, and subsequently the phosphorylated forms of TAK1 rapidly disappeared. Intermolecular autophosphorylation of Thr-187 was essential for TAK1 activation. RNA interference and overexpression experiments demonstrated that TAK1-binding protein TAB1 and TAB2 were involved in the phosphorylation of TAK1, but they regulated TAK1 phosphorylation differentially. Furthermore, SB203580 and p38alpha small interfering RNA enhanced TNF-alpha-induced Thr-187 phosphorylation as well as TAK1 kinase activity, indicating that the phosphorylation is affected by p38alpha/TAB1/TAB2-mediated feedback control of TAK1. These results indicate critical roles of Thr-187 phosphorylation in the stress-induced rapid and transient activation of TAK1 in a signaling complex containing TAB1 and TAB2.
authors.affiliation: Division of Pathogenic Biochemistry, Institute of Natural Medicine, 21st Century Center of Excellence (COE) Program, Toyama Medical and Pharmaceutical University, Toyama 930-0194, Japan.
authors.forename: Pattama
authors.initials: P
authors.lastname: Singhirunnusorn
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Suzuki
authors.forename: Noritaka
authors.initials: N
authors.lastname: Kawasaki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Saiki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Sakurai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000737:chemistry; D010766:Phosphorylation; D015398:Signal Transduction; D013312:Stress, Physiological / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism*; D014162:Transfection; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D020930:MAP Kinase Kinase Kinases; D046912:Multiprotein Complexes; D013912:Threonine; D000099151:MAP Kinase Kinase Kinase 7; C486300:TAB1 protein, human; C410585:TAB2 protein, human