title: TNF-receptor associated factor 6-deficient fibroblast is sensitive to the TNF-alpha-induced cell death: involvement of reactive oxygen species.
abstract: Tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) has mainly been involved in signaling from CD40 and IL-1 receptor family. While TNF-alpha exerts various biological effects including cell death, the role of TRAF6 in the TNF-alpha signaling remains to be unclear. Here, we demonstrated that murine embryonic fibroblasts (MEFs) derived from TRAF6 knockout (TRAF6KO) mice have increased sensitivity to actinomycin D plus TNF-alpha-induced cell death compared with wild-type MEF. Reactive oxygen species (ROS) were accumulated more in TRAF6KO MEF than in wild-type MEF. An antioxidant, butylated hydroxyanisole (BHA) completely inhibited TNF-alpha-induced cell death and DNA fragmentation. Thus, the TNF-alpha-induced cell death in TRAF6KO MEF was ROS-dependent. Reconstitution of full-length TRAF6 but not N-terminal-deleted TRAF6 constructs in TRAF6KO MEF reversed TNF-alpha-induced cell death, ROS accumulation, and DNA fragmentation completely. Thus, we concluded that resistance against TNF-alpha-induced cell death is rendered by TRAF6, which regulates ROS accumulation.
authors.affiliation: Department of Biochemistry, Kyoritsu University of Pharmacy, 1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512, Japan.
authors.forename: Daiju
authors.initials: D
authors.lastname: Ichikawa
authors.forename: Megumi
authors.initials: M
authors.lastname: Funakoshi-Tago
authors.forename: Eriko
authors.initials: E
authors.lastname: Aizu-Yokota
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sonoda
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Inoue
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kasahara
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D017382:Reactive Oxygen Species / Q000378:metabolism*; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage*
chemical_list: D017382:Reactive Oxygen Species; D048029:TNF Receptor-Associated Factor 6; D014409:Tumor Necrosis Factor-alpha