IRAK-4: a novel member of the IRAK family with the properties of an IRAK-kinase.

Tularik, Inc., 2 Corporate Drive, South San Francisco, CA 94080, USA.
Toll/IL-1 receptor family members are central components of host defense mechanisms in a variety of species. One well conserved element in their signal transduction is Ser/Thr kinases, which couple early signaling events in a receptor complex at the plasma membrane to larger signalosomes in the cytosol. The fruit fly Drosophila melanogaster has one member of this family of kinases, termed Pelle. The complexity of this pathway is vastly increased in vertebrates, and several Pelle homologs have been described and termed IL-1 receptor-associated kinase (IRAK). Here we report the identification of a novel and distinct member of the IRAK family, IRAK-4. IRAK-4 is the closest human homolog to Pelle. Endogenous IRAK-4 interacts with IRAK-1 and TRAF6 in an IL-1-dependent manner, and overexpression of IRAK-4 can activate NF-kappa B as well as mitogen-activated protein (MAP) kinase pathways. Most strikingly, and in contrast to the other IRAKs, IRAK-4 depends on its kinase activity to activate NF-kappa B. In addition, IRAK-4 is able to phosphorylate IRAK-1, and overexpression of dominant-negative IRAK-4 is blocking the IL-1-induced activation and modification of IRAK-1, suggesting a role of IRAK-4 as a central element in the early signal transduction of Toll/IL-1 receptors, upstream of IRAK-1.
Mesh Terms:
Amino Acid Sequence, Animals, Blotting, Northern, Cloning, Molecular, DNA, Complementary, Drosophila Proteins, Drosophila melanogaster, Enzyme Activation, Genes, Reporter, Humans, Immunoblotting, Interleukin-1, Interleukin-1 Receptor-Associated Kinases, JNK Mitogen-Activated Protein Kinases, MAP Kinase Kinase 4, MAP Kinase Signaling System, Mitogen-Activated Protein Kinase Kinases, Mitogen-Activated Protein Kinases, Molecular Sequence Data, Multigene Family, NF-kappa B, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor), Polymerase Chain Reaction, Precipitin Tests, Protein Binding, Protein Kinases, Protein-Serine-Threonine Kinases, Proteins, Receptors, Interleukin-1, Recombinant Proteins, Signal Transduction, TNF Receptor-Associated Factor 6, Time Factors, Tissue Distribution
Proc. Natl. Acad. Sci. U.S.A. Apr. 16, 2002; 99(8);5567-72 [PUBMED:11960013]
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