We recently demonstrated that the tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) helps maintenance of cell survival by regulating glycogen synthase kinase 3 beta (GSK3 beta) activity during TNF signaling. However, the molecular linkage between TRAM and GSK3 beta signaling is unknown. Herein, we showed that TRAF6 positively regulated cell survival by modulating PI3K-Akt-GSK3 beta cascades. In 3T3 cells lacking TRAF6, but not those lacking TRAF2, TNF stimulation led to prolonged hyperphosphorylation of Akt, which coincided with the activation of upstream PI3K. Pharmacologically blocking PI3K significantly inhibited Akt and GSK3 beta phosphorylation. Importantly, PI3K inhibition rescued cell death in TRAF6-null 3T3 cells. These data suggested TRAF6 regulates TNF-mediated cell survival through PI3KAkt-GSK3 beta cascades. (c) 2008 Elsevier Inc. All rights reserved.