TAK1 lysine 158 is required for TGF-beta-induced TRAF6-mediated Smad-independent IKK/NF-kappa B and JNK/AP-1 activation

Lys63-linked TAK1 polyubiquitination plays an essential role in the regulation of TAK1 activation. TRAF6-mediated Lys63-linked polyubiquitylation of TAK1 has been shown to be required for TGF-beta-induced TAK1 activation. However, it remains unclear which lysine residue on TAK1 is TRAF6-mediated TAK1 polyubiquitination acceptor site in TGF-beta signaling pathway. Here we report that lysine 158 on TAK1 is required for TGF-beta-induced TRAF6-mediated TAK1 polyubiquitination and TAK1-mediated IKK, JNK and p38 activation. Notably, in contrast to TAK1 wild-type and K34R mutant, TAK1 K158R mutant co-overexpression with TAB1 failed to induce Lys63-linked TAK1 polyubiquitination. TRAF6-induced K63-linked TAK1 polyubiquitination was blocked by TAK1 K158R mutation, but not by K34R mutation. Furthermore, TGF-beta-induced TAK1 polyubiquitination was inhibited by TAK1 K158R mutation, but not by K34R mutation in HeLa cells. Reconstitution of TAK1-deficient mouse embryo fibroblast cells with TAK1 wild-type, K158R mutant, or K34R mutant reveals that TAK1 lysine 158 residue is required for TGF-beta-induced IKK, p38 and JNK activation. (C) 2010 Elsevier Inc. All rights reserved.