title: AIP1 mediates TNF-alpha-induced ASK1 activation by facilitating dissociation of ASK1 from its inhibitor 14-3-3.
abstract: TNF-alpha activates ASK1 in part by dissociating 14-3-3 from apoptosis signal-regulating kinase 1 (ASK1). In the present study, we identified a novel Ras GTPase-activating protein (Ras-GAP) as an ASK1-interacting protein (AIP1). AIP1 binds to the C-terminal domain of ASK1 via a lysine-rich cluster within the N-terminal C2 domain. AIP1 exists in a closed form through an intramolecular interaction between the N-terminus and the C-terminus, and TNF-alpha induces unfolding of AIP1 leading to association of AIP1 with ASK1. Thus, the N-terminus of AIP1 containing the C2 and GAP domains constitutively binds to ASK1 and facilitates the release of 14-3-3 from ASK1. In contrast to 14-3-3, AIP1 binds preferentially to dephosphorylated ASK1. Recruited AIP1 enhances ASK1-induced JNK activation, and the ASK1 binding and the GAP activity of AIP1 are critical for AIP1-enhanced ASK1 activation. Furthermore, TNF-induced ASK1/JNK activation is significantly blunted in cells where AIP1 is knocked down by RNA interference. These data suggest that AIP1 mediates TNF-alpha-induced ASK1 activation by facilitating dissociation of inhibitor 14-3-3 from ASK1, a novel mechanism by which TNF-alpha activates ASK1.
authors.affiliation: Center for Cardiovascular Research, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
authors.forename: Xiangrong
authors.initials: X
authors.lastname: He
authors.forename: Weimin
authors.initials: W
authors.lastname: Liu
authors.forename: Meng
authors.initials: M
authors.lastname: Lu
authors.forename: Jer-Tsong
authors.initials: JT
authors.lastname: Hsieh
authors.forename: Wang
authors.initials: W
authors.lastname: Min
mesh_terms: D048948:14-3-3 Proteins; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D004730:Endothelium, Vascular / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology*; D020935:MAP Kinase Signaling System; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D020703:ras GTPase-Activating Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D048948:14-3-3 Proteins; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D020703:ras GTPase-Activating Proteins; D014446:Tyrosine 3-Monooxygenase; D048848:MAP Kinase Kinase Kinase 5; D020930:MAP Kinase Kinase Kinases; C482858:MAP3K5 protein, human