Transforming Growth Factor β-activated Kinase 1 (TAK1) Kinase Adaptor, TAK1-binding Protein 2, Plays Dual Roles in TAK1 Signaling by Recruiting Both an Activator and an Inhibitor of TAK1 Kinase in Tumor Necrosis Factor Signaling Pathway

Peter Broglie,Kunihiro Matsumoto,Shizuo Akira,David L Brautigan,Jun Ninomiya-Tsuji

doi:10.1074/jbc.m109.090522

Abstract

Transforming growth factor beta-activated kinase 1 (TAK1) kinase is an indispensable signaling intermediate in tumor necrosis factor (TNF), interleukin 1, and Toll-like receptor signaling pathways. TAK1-binding protein 2 (TAB2) and its closely related protein, TAB3, are binding partners of TAK1 and have previously been identified as adaptors of TAK1 that recruit TAK1 to a TNF receptor signaling complex. TAB2 and TAB3 redundantly mediate activation of TAK1. In this study, we investigated the role of TAB2 by analyzing fibroblasts having targeted deletion of the tab2 gene. In TAB2-deficient fibroblasts, TAK1 was associated with TAB3 and was activated following TNF stimulation. However, TAB2-deficient fibroblasts displayed a significantly prolonged activation of TAK1 compared with wild type control cells. This suggests that TAB2 mediates deactivation of TAK1. We found that a TAK1-negative regulator, protein phosphatase 6 (PP6), was recruited to the TAK1 complex in wild type but not in TAB2-deficient fibroblasts. Furthermore, we demonstrated that both PP6 and TAB2 interacted with the polyubiquitin chains and this interaction mediated the assembly with TAK1. Our results indicate that TAB2 not only activates TAK1 but also plays an essential role in the deactivation of TAK1 by recruiting PP6 through a polyubiquitin chain-dependent mechanism.

Highlights

Serine/threonine-protein phosphatase 6 (PP6) is a member of type 2A serine/threonine phosphatase family [10]
We found that MAPK family member Jun N-terminal kinase (JNK) was activated in both control and TAK1-binding protein 2 (TAB2)-deficient fibroblasts following tumor necrosis factor (TNF) treatment; the activation of JNK was prolonged in TAB2Ϫ/Ϫ cells (Fig. 1B)
We found that the increased levels of phosphorylated Transforming growth factor ␤-activated kinase 1 (TAK1) by okadaic acid (OA) treatment was less pronounced in TAB2-deficient fibroblasts, and OA treatment normalized the levels of TAK1 activation in control and TAB2-deficient fibroblasts (Fig. 3A)

Summary

Introduction

Serine/threonine-protein phosphatase 6 (PP6) is a member of type 2A serine/threonine phosphatase family [10]. We found that MAPK family member JNK was activated in both control and TAB2-deficient fibroblasts following TNF treatment; the activation of JNK was prolonged in TAB2Ϫ/Ϫ cells (Fig. 1B). TAB3 was detected in TAK1 immunoprecipitates in both control and TAB2-deficient fibroblasts (Fig. 2B).

Results

Conclusion