TAK1 is Critical for IκB Kinase-mediated Activation of the NF-κB Pathway

Cytokine treatment stimulates the IκB kinases, IKKα and IKKβ, which phosphorylate the IκB proteins, leading to their degradation and activation of NF-κB regulated genes. A clear definition of the specific roles of IKKα and IKKβ in activating the NF-κB pathway and the upstream kinases that regulate IKK activity remain to be elucidated. Here, we utilized small interfering RNAs (siRNAs) directed against IKKα, IKKβ and the upstream regulatory kinase TAK1 in order to better define their roles in cytokine-induced activation of the NF-κB pathway. In contrast to previous results with mouse embryo fibroblasts lacking either IKKα or IKKβ, which indicated that only IKKβ is involved in cytokine-induced NF-κB activation, we found that both IKKα and IKKβ were important in activating the NF-κB pathway. Furthermore, we found that the MAP3K TAK1, which has been implicated in IL-1-induced activation of the NF-κB pathway, was also critical for TNFα-induced activation of the NF-κB pathway. TNFα activation of the NF-κB pathway is associated with the inducible binding of TAK1 to TRAF2 and both IKKα and IKKβ. This analysis further defines the distinct in vivo roles of IKKα, IKKβ and TAK1 in cytokine-induced activation of the NF-κB pathway.

[1]  A. Israël,et al.  Complete lack of NF-kappaB activity in IKK1 and IKK2 double-deficient mice: additional defect in neurulation. , 2000, Genes & development.

[2]  D. Wallach,et al.  Identification of a cell protein (FIP-3) as a modulator of NF-κB activity and as a target of an adenovirus inhibitor of tumor necrosis factor α-induced apoptosis , 1999 .

[3]  I. Verma,et al.  IKK1-deficient mice exhibit abnormal development of skin and skeleton. , 1999, Genes & development.

[4]  R. Gaynor,et al.  Analysis of Domains in the IKKα and IKKβ Proteins That Regulate Their Kinase Activity* , 2000, The Journal of Biological Chemistry.

[5]  S. Akira,et al.  Iκb Kinase α Is Essential for Mature B Cell Development and Function , 2001, The Journal of experimental medicine.

[6]  M. Mann,et al.  IκB Kinase (IKK)-Associated Protein 1, a Common Component of the Heterogeneous IKK Complex , 1999, Molecular and Cellular Biology.

[7]  T. Tuschl,et al.  RNA interference is mediated by 21- and 22-nucleotide RNAs. , 2001, Genes & development.

[8]  K. Irie,et al.  TAB2, a novel adaptor protein, mediates activation of TAK1 MAPKKK by linking TAK1 to TRAF6 in the IL-1 signal transduction pathway. , 2000, Molecular cell.

[9]  A. Baldwin,et al.  THE NF-κB AND IκB PROTEINS: New Discoveries and Insights , 1996 .

[10]  H. Pahl.  Activators and target genes of Rel/NF-κB transcription factors , 1999, Oncogene.

[11]  A. Fire,et al.  Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans , 1998, Nature.

[12]  D. Goeddel,et al.  Identification and Characterization of an IκB Kinase , 1997, Cell.

[13]  V. Dixit,et al.  The A20 zinc finger protein protects cells from tumor necrosis factor cytotoxicity. , 1992, The Journal of biological chemistry.

[14]  T. Deerinck,et al.  Abnormal Morphogenesis But Intact IKK Activation in Mice Lacking the IKKα Subunit of IκB Kinase , 1999 .

[15]  R. Gaynor,et al.  Domains in the SPT5 Protein That Modulate Its Transcriptional Regulatory Properties , 2000, Molecular and Cellular Biology.

[16]  P. Sharp,et al.  RNA interference--2001. , 2001, Genes & development.

[17]  S. Akira,et al.  Limb and skin abnormalities in mice lacking IKKalpha. , 1999, Science.

[18]  K. Irie,et al.  TAK1 Mediates the Ceramide Signaling to Stress-activated Protein Kinase/c-Jun N-terminal Kinase* , 1997, The Journal of Biological Chemistry.

[19]  David Baltimore,et al.  NF-κB: Ten Years After , 1996, Cell.

[20]  M J May,et al.  NF-kappa B and Rel proteins: evolutionarily conserved mediators of immune responses. , 1998, Annual review of immunology.

[21]  E. Zandi,et al.  IKK-γ is an essential regulatory subunit of the IκB kinase complex , 1998, Nature.

[22]  K. Irie,et al.  Identification of a Member of the MAPKKK Family as a Potential Mediator of TGF-β Signal Transduction , 1995, Science.

[23]  D. Rio,et al.  The conserved pre-mRNA splicing factor U2AF from Drosophila: requirement for viability. , 1993, Science.

[24]  T. Deerinck,et al.  The IKKβ Subunit of IκB Kinase (IKK) is Essential for Nuclear Factor κB Activation and Prevention of Apoptosis , 1999, The Journal of experimental medicine.

[25]  Zhijian J. Chen,et al.  Activation of the IκB Kinase Complex by TRAF6 Requires a Dimeric Ubiquitin-Conjugating Enzyme Complex and a Unique Polyubiquitin Chain , 2000, Cell.

[26]  R. Gaynor,et al.  IKKγ/NEMO Facilitates the Recruitment of the IκB Proteins into the IκB Kinase Complex* , 2001, The Journal of Biological Chemistry.

[27]  G. Stark,et al.  Interleukin-1 (IL-1) Receptor-Associated Kinase Leads to Activation of TAK1 by Inducing TAB2 Translocation in the IL-1 Signaling Pathway , 2001, Molecular and Cellular Biology.

[28]  K. Irie,et al.  TAB1: An Activator of the TAK1 MAPKKK in TGF-β Signal Transduction , 1996, Science.

[29]  B. Bass.  Double-Stranded RNA as a Template for Gene Silencing , 2000, Cell.

[30]  N. Sakurai,et al.  Receptor activator of NF-kappaB ligand (RANKL) activates TAK1 mitogen-activated protein kinase kinase kinase through a signaling complex containing RANK, TAB2, and TRAF6. , 2002, Molecular and cellular biology.

[31]  M. Karin.  How NF-κB is activated: the role of the IκB kinase (IKK) complex , 1999, Oncogene.

[32]  E. Zandi,et al.  The IκB Kinase Complex (IKK) Contains Two Kinase Subunits, IKKα and IKKβ, Necessary for IκB Phosphorylation and NF-κB Activation , 1997, Cell.

[33]  David M. Rothwarf,et al.  A cytokine-responsive IκB kinase that activates the transcription factor NF-κB , 1997, Nature.

[34]  M. Karin,et al.  The α and β Subunits of IκB Kinase (IKK) Mediate TRAF2-Dependent IKK Recruitment to Tumor Necrosis Factor (TNF) Receptor 1 in Response to TNF , 2001, Molecular and Cellular Biology.

[35]  Zhijian J. Chen,et al.  TAK1 is a ubiquitin-dependent kinase of MKK and IKK , 2001, Nature.

[36]  A. Fire,et al.  Specific inhibition of gene expression by small double-stranded RNAs in invertebrate and vertebrate systems , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[37]  Matthias Mann,et al.  IKK-1 and IKK-2: Cytokine-Activated IκB Kinases Essential for NF-κB Activation , 1997 .

[38]  D. Goeddel,et al.  Embryonic Lethality, Liver Degeneration, and Impaired NF-κB Activation in IKK-β-Deficient Mice , 1999 .

[39]  T. Tuschl,et al.  Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells , 2001, Nature.

[40]  Mike Rothe,et al.  IκB Kinase-β: NF-κB Activation and Complex Formation with IκB Kinase-α and NIK , 1997 .

[41]  J. Ninomiya-Tsuji,et al.  The kinase TAK1 can activate the NIK-IκB as well as the MAP kinase cascade in the IL-1 signalling pathway , 1999, Nature.

[42]  E. Zandi,et al.  Bridging the Gap: Composition, Regulation, and Physiological Function of the IκB Kinase Complex , 1999, Molecular and Cellular Biology.

[43]  W. Toriumi,et al.  Functional Interactions of Transforming Growth Factor β-activated Kinase 1 with IκB Kinases to Stimulate NF-κB Activation* , 1999, The Journal of Biological Chemistry.

[44]  G. Courtois,et al.  Complementation Cloning of NEMO, a Component of the IκB Kinase Complex Essential for NF-κB Activation , 1998, Cell.

[45]  Inder M. Verma,et al.  Severe Liver Degeneration in Mice Lacking the IκB Kinase 2 Gene , 1999 .

[46]  Thomas Tuschl,et al.  Expanding small RNA interference , 2002, Nature Biotechnology.