Monosodium urate(MSU)crystals activate inflammatory pathways that overlap with interleukin-1β(IL-1β)signaling.However,the post-translational mechanisms involved and the role of signaling proteins in this activation ...Monosodium urate(MSU)crystals activate inflammatory pathways that overlap with interleukin-1β(IL-1β)signaling.However,the post-translational mechanisms involved and the role of signaling proteins in this activation are unknown.In the present study,we investigated the intracellular signaling mechanisms involved in MSU-induced activation of THP-1 macrophages and human nondiseased synovial fibroblasts(NLSFs)and the in vivo efficacy of an inhibitor of tumor grovArth factor-β(TGF-β)-activated kinase 1(TAK1),5Z-7-oxozeaenoI,in MSU-induced paw inflammation in C57BL76 mice.THP-1 macrophage activation with MSU crystals(25-200 ng/ml)resulted in the rapid and sustained phosphorylation of interleukin-1 receptor-activated kinase 1(IRAK1 Thr^(209))and TAK1(Thr^(184/187))and their association with the E3 ubiquitin ligase TRAF6.At the cellular level,MSU inhibited the deubiquitinases A20 and UCHL2 and increased 20s proteasomal activity,leading to a global decrease in K^(63)-linked ubiquitination and increase in K^(48)-linked ubiquitination in THP-1 macrophages.While MSU did not stimulate cytokine produaion in NLSFs,it significantly amplified IL-1β-induced IL-6,IL-8,and ENA-78/CXCL5 production.Docking studies and MD simulations followed by TAK1 in vitro kinase assays revealed that uric acid molecules are capable of arresting TAK1 in an active-state conformation,resulting in sustained TAK1 kinase activation.Importantly,MSU-induced proinflammatory cytokine production was completely inhibited by 5Z-7-oxozeaenol but not IRAK1/4 or TRAF6 inhibitors.Administration of 5Z-7-oxozeaenol(5 or 15 mg/kg;orally)significantly inhibited MSU-induced paw inflammation in C57BL/6 mice.Our study identifies a novel post-translational mechanism of TAK1 activation by MSU and suggests the therapeutic potential of TAK1 in regulating MSU-induced Inflammation.展开更多
基金This study was supported by start-up funds from Washington State University.
文摘Monosodium urate(MSU)crystals activate inflammatory pathways that overlap with interleukin-1β(IL-1β)signaling.However,the post-translational mechanisms involved and the role of signaling proteins in this activation are unknown.In the present study,we investigated the intracellular signaling mechanisms involved in MSU-induced activation of THP-1 macrophages and human nondiseased synovial fibroblasts(NLSFs)and the in vivo efficacy of an inhibitor of tumor grovArth factor-β(TGF-β)-activated kinase 1(TAK1),5Z-7-oxozeaenoI,in MSU-induced paw inflammation in C57BL76 mice.THP-1 macrophage activation with MSU crystals(25-200 ng/ml)resulted in the rapid and sustained phosphorylation of interleukin-1 receptor-activated kinase 1(IRAK1 Thr^(209))and TAK1(Thr^(184/187))and their association with the E3 ubiquitin ligase TRAF6.At the cellular level,MSU inhibited the deubiquitinases A20 and UCHL2 and increased 20s proteasomal activity,leading to a global decrease in K^(63)-linked ubiquitination and increase in K^(48)-linked ubiquitination in THP-1 macrophages.While MSU did not stimulate cytokine produaion in NLSFs,it significantly amplified IL-1β-induced IL-6,IL-8,and ENA-78/CXCL5 production.Docking studies and MD simulations followed by TAK1 in vitro kinase assays revealed that uric acid molecules are capable of arresting TAK1 in an active-state conformation,resulting in sustained TAK1 kinase activation.Importantly,MSU-induced proinflammatory cytokine production was completely inhibited by 5Z-7-oxozeaenol but not IRAK1/4 or TRAF6 inhibitors.Administration of 5Z-7-oxozeaenol(5 or 15 mg/kg;orally)significantly inhibited MSU-induced paw inflammation in C57BL/6 mice.Our study identifies a novel post-translational mechanism of TAK1 activation by MSU and suggests the therapeutic potential of TAK1 in regulating MSU-induced Inflammation.
