title: Apoptosis signal-regulating kinase (ASK)-1 mediates apoptosis through activation of JNK1 following engagement of membrane immunoglobulin.
abstract: Engagement of membrane immunoglobulin (mIg) on WEHI-231 mouse B lymphoma cells results in growth arrest at the G1 phase of the cell cycle, followed by a reduction of mitochondrial membrane potential (DeltaPsim) and apoptosis. WEHI-231 cells resemble immature B cells in terms of the cell surface phenotype and sensitivity to mIg engagement. However, the molecular mechanisms underlying mIg-induced loss of DeltaPsim and apoptosis have not yet been established. In this study, we show that apoptosis signal-regulating kinase 1 (ASK1)-c-Jun N-terminal kinase 1 (JNK1) signaling pathway participates in mIg-induced apoptosis through the generation of reactive oxygen species (ROS). Stimulation of WEHI-231 cells with anti-IgM induces phosphorylation and subsequent activation of ASK1, leading to JNK activation. Anti-IgM stimulation immediately (5 min) induces hydrogen peroxide (H2O2) production with a substantial increase during later time points (36-48 h), accompanied by loss of DeltaPsim and an increase in cells with sub-G1 DNA content. The anti-IgM-induced late-phase H2O2 production, loss of DeltaPsim, and increase in the sub-G1 fraction were all reduced substantially in WEHI-231 cells overexpressing a dominant-negative form of ASK1, compared with control vector alone, but enhanced substantially in cells overexpressing a constitutively active form of ASK1. These mIg-mediated events were also partially abrogated by ROS scavenger N-acetyl-L-cysteine (NAC). Taken together, these results suggest that mIg engagement induces H2O2 production leading to activation of ASK1-JNK1 pathway, creating a feedback amplification loop of ROS-ASK/JNK that leads to loss of DeltaPsim and finally apoptosis.
authors.affiliation: Department of Immunology and Intractable Immunology Research Center, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan.
authors.forename: Masae
authors.initials: M
authors.lastname: Furuhata
authors.forename: Eiko
authors.initials: E
authors.lastname: Takada
authors.forename: Takaya
authors.initials: T
authors.lastname: Noguchi
authors.forename: Hidenori
authors.initials: H
authors.lastname: Ichijo
authors.forename: Junichiro
authors.initials: J
authors.lastname: Mizuguchi
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D001402:B-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D016193:G1 Phase / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D048848:MAP Kinase Kinase Kinase 5 / Q000235:genetics / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000276:immunology; D021381:Protein Transport / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D014162:Transfection; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000888:Antibodies, Anti-Idiotypic; C494827:Bax protein, mouse; D017382:Reactive Oxygen Species; D011947:Receptors, Antigen, B-Cell; C044203:anti-IgM; D051028:bcl-2-Associated X Protein; D006861:Hydrogen Peroxide; D048055:Mitogen-Activated Protein Kinase 8; D048848:MAP Kinase Kinase Kinase 5; C482859:Map3k5 protein, mouse; D000111:Acetylcysteine