title: Interleukin-1 receptor-associated kinase 2 is critical for lipopolysaccharide-mediated post-transcriptional control.
abstract: IRAK2, a member of the interleukin-1 receptor-associated kinase (IRAK) family, has been implicated in Toll-like receptor (TLR)-mediated signaling. We generated IRAK2-deficient mice to examine its function in detail. These mice are resistant to lipopolysaccharide-induced septic shock, because of impaired TLR4-mediated induction of pro-inflammatory cytokines and chemokines. Although IRAK2 deficiency did not affect TLR4-mediated NFkappaB activation, a reduction of lipopolysaccharide (LPS)-mediated mRNA stabilization contributed to the reduced cytokine and chemokine production observed in bone marrow-derived macrophages from IRAK2-deficient mice. Furthermore, the ratios of LPS-induced cytokine and chemokine mRNAs in translation-active (polysomal) versus translation-inactive (free ribosomes) pools were reduced in IRAK2-deficient macrophages compared with wild type macrophages. Importantly, LPS-induced phosphorylation of MKK3/6, MNK1, and eIF4E was significantly reduced in IRAK2-deficient macrophages compared with wild type macrophages. Moreover, LPS stimulation induced an interaction of IRAK2 with TRAF6, MKK3/6, and MK2, implicating a critical role for mitogen-activated protein kinase signaling in LPS-induced IRAK2-mediated post-transcriptional control. These results reveal that IRAK2 is required for LPS-mediated post-transcriptional control of cytokine and chemokine expression, which plays an essential role in TLR4-induced septic shock.
authors.affiliation: Departments of Molecular Genetics and Immunology, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: Youzhong
authors.initials: Y
authors.lastname: Wan
authors.forename: Hui
authors.initials: H
authors.lastname: Xiao
authors.forename: Jeremy
authors.initials: J
authors.lastname: Affolter
authors.forename: Tae Whan
authors.initials: TW
authors.lastname: Kim
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Bulek
authors.forename: Sujan
authors.initials: S
authors.lastname: Chaudhuri
authors.forename: Deborah
authors.initials: D
authors.lastname: Carlson
authors.forename: Thomas
authors.initials: T
authors.lastname: Hamilton
authors.forename: Barsanjit
authors.initials: B
authors.lastname: Mazumder
authors.forename: George R
authors.initials: GR
authors.lastname: Stark
authors.forename: James
authors.initials: J
authors.lastname: Thomas
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Li
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000502:physiology; D018925:Chemokines / Q000235:genetics / Q000276:immunology; D016207:Cytokines / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects*; D053592:Interleukin-1 Receptor-Associated Kinases / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology; D014158:Transcription, Genetic
chemical_list: D018925:Chemokines; D016207:Cytokines; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D053592:Interleukin-1 Receptor-Associated Kinases; D020928:Mitogen-Activated Protein Kinases