title: Interleukin 1/Toll-like receptor-induced autophosphorylation activates interleukin 1 receptor-associated kinase 4 and controls cytokine induction in a cell type-specific manner.
abstract: IRAK4 is a central kinase in innate immunity, but the role of its kinase activity is controversial. The mechanism of activation for IRAK4 is currently unknown, and little is known about the role of IRAK4 kinase in cytokine production, particularly in different human cell types. We show IRAK4 autophosphorylation occurs by an intermolecular reaction and that autophosphorylation is required for full catalytic activity of the kinase. Phosphorylation of any two of the residues Thr-342, Thr-345, and Ser-346 is required for full activity, and the death domain regulates the activation of IRAK4. Using antibodies against activated IRAK4, we demonstrate that IRAK4 becomes phosphorylated in human cells following stimulation by IL-1R and Toll-like receptor agonists, which can be blocked pharmacologically by a dual inhibitor of IRAK4 and IRAK1. Interestingly, in dermal fibroblasts, although complete inhibition of IRAK4 kinase activity does not inhibit IL-1-induced IL-6 production, NF-κB, or MAPK activation, there is complete ablation of these processes in IRAK4-deficient cells. In contrast, the inhibition of IRAK kinase activity in primary human monocytes reduces R848-induced IL-6 production with minimal effect on NF-κB or MAPK activation. Taken together, these studies define the mechanism of IRAK4 activation and highlight the differential role of IRAK4 kinase activity in different human cell types as well as the distinct roles IRAK4 scaffolding and kinase functions play.
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Leah
authors.initials: L
authors.lastname: Cushing
authors.affiliation: Global Biological Technology, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Wayne
authors.initials: W
authors.lastname: Stochaj
authors.affiliation: Pfizer Chemical Technologies Section, Pearl River, New York 10965.
authors.forename: Marshall
authors.initials: M
authors.lastname: Siegel
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Robert
authors.initials: R
authors.lastname: Czerwinski
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Ken
authors.initials: K
authors.lastname: Dower
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Wright
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
authors.forename: Margaret
authors.initials: M
authors.lastname: Hirschfield
authors.affiliation: St. Giles Laboratory of Human Genetics of Infectious Diseases Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Pediatric Hematology-Immunology Unit, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France.
authors.forename: Jean-Laurent
authors.initials: JL
authors.lastname: Casanova
authors.affiliation: Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; Study Center for Primary Immunodeficiencies, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France.
authors.forename: Capucine
authors.initials: C
authors.lastname: Picard
authors.affiliation: St. Giles Laboratory of Human Genetics of Infectious Diseases Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Puel
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140. Electronic address: Lih-Ling.Lin@pfizer.com.
authors.forename: Lih-Ling
authors.initials: LL
authors.lastname: Lin
authors.affiliation: Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140. Electronic address: Vikram.Rao@pfizer.com.
authors.forename: Vikram R
authors.initials: VR
authors.lastname: Rao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002474:Cell-Free System; D003001:Cloning, Molecular; D016207:Cytokines / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D057809:HEK293 Cells; D006801:Humans; D007113:Immunity, Innate; D007313:Insecta; D053592:Interleukin-1 Receptor-Associated Kinases / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D016366:Open Reading Frames; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017472:Receptors, Interleukin-1 / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism; D051193:Toll-Like Receptors / Q000819:agonists / Q000378:metabolism*
chemical_list: D016207:Cytokines; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D016328:NF-kappa B; D017472:Receptors, Interleukin-1; D051193:Toll-Like Receptors; C507773:IRAK4 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases
keywords: Innate Immunity; Interleukin 1 (IL-1); Interleukin Receptor-associated Kinase (IRAK); Interleukin Receptor-associated Kinase 4 (IRAK4); Protein Kinases; Protein Phosphorylation; Toll-like Receptors (TLR)