TNF-receptor associated factor 6-deficient fibroblast is sensitive to the TNF-α-induced cell death: Involvement of reactive oxygen species

Tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) has mainly been involved in signaling from CD40 and IL-1 receptor family. While TNF-α exerts various biological effects including cell death, the role of TRAF6 in the TNF-α 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-α-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-α-induced cell death and DNA fragmentation. Thus, the TNF-α-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-α-induced cell death, ROS accumulation, and DNA fragmentation completely. Thus, we concluded that resistance against TNF-α-induced cell death is rendered by TRAF6, which regulates ROS accumulation.