title: The interleukin-1 receptor associated kinase 1 contributes to the regulation of NFAT.
abstract: IRAK-1 is a critical modulator regulating innate immunity signaling processes. However, the physiological substrates for IRAK-1 remain poorly defined. In this report, we have demonstrated that IRAK-1 is a kinase responsible for the constitutive phosphorylation and inactivation of the Nuclear Factor of Activated T-cell (NFAT). Expression of IRAK-1 suppressed NFAT reporter activity. Correspondingly, the levels of both nuclear NFATc1 and NFATc4 were constitutively elevated in IRAK-1-/- cells. Furthermore, the phosphorylation of NFATc4 at the S168PS170P site was significantly diminished in IRAK-1-/- cells. Mechanistically, we observed that IRAK-1 interacted with NFATc4 via the C-terminus of IRAK-1 and the N-terminal NHR region of NFATc4. IRAK-1 mutants that ablated either its kinase activity or its interaction with NFATc4 failed to suppress NFAT reporter activity. The expression level of COX2, which is under the control of NFAT, was elevated in IRAK-1-/- cells. Functionally, ApoE-/-/IRAK-1-/- mice were protected from high-fat-diet-induced hypertension and atherosclerosis. Taken together, our findings reveal NFAT molecules as novel physiological targets for IRAK-1.
authors.affiliation: The Laboratory of Innate Immunity and Inflammation, Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, United States.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Wang
authors.forename: Stephan
authors.initials: S
authors.lastname: Fasciano
authors.forename: Liwu
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D050197:Atherosclerosis / Q000209:etiology / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage; D006801:Humans; D006973:Hypertension / Q000209:etiology / Q000378:metabolism; D053592:Interleukin-1 Receptor-Associated Kinases / Q000235:genetics / Q000502:physiology*; D008264:Macrophages / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D001057:Apolipoproteins E; D004041:Dietary Fats; D050778:NFATC Transcription Factors; C467907:Nfatc4 protein, mouse; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D053592:Interleukin-1 Receptor-Associated Kinases