Project description:IRAK4 kinase plays a critical role in innate immune responses and inflammation by modulating the TLR/IL-1R signaling pathway, yet the mechanism by which it regulates downstream pathways and transcription factors to induce inflammatory cytokines is unclear. IRAK4 can mediate signaling events by mechanisms both dependent and independent of its kinase activity. Understanding this regulation is important for deciphering the role of IRAK4 and for the development of treatments for inflammatory diseases and cancer. Through transcriptomic and biochemical analyses of primary human monocytes treated with a highly potent and selective inhibitor of IRAK4, we show that IRAK4 kinase activity controls the transcription factor IRF5 which in turn induces inflammatory cytokine and type I interferon transcription in myeloid cells. We also show that IRAK4 kinase activity does not control activation of NF-κB. Following TLR stimulation, translocation of IRF5, but not NF-κB, to the nucleus in human monocytes is abolished by IRAK4 kinase inhibition. In addition, binding of IRF5, but not NF-κB p65, to promoters of inflammatory target genes (TNF-α and IP10) is blocked with an IRAK4 kinase inhibitor. IKKβ, a known activator of IRF5, is phosphorylated in response to TLR mediated signaling, and inhibition of IRAK4 kinase blocks IKKβ phosphorylation. Pharmacological inhibition of IKKβ and TAK1, the upstream kinase of IKKβ, in human monocytes blocks IL-1, IL-6 and TNF-α cytokine production, as well as IRF5 translocation to the nucleus. Taken together, our data suggest a novel mechanism by which IRAK4 kinase activity regulates TAK1 and IKKβ activation, leading to the translocation of IRF5 and induction of inflammatory cytokines in human monocytes.
Project description:Exciting discoveries related to IL-1R/TLR signaling in development of atherosclerosis plaque have triggered intense interest in the molecular mechanisms by which innate immune signaling modulates the onset and development of atherosclerosis. Previous studies have clearly shown the definitive role of proinflammatory cytokine IL-1 in the development of atherosclerosis. Recent studies have provided direct evidence supporting a link between innate immunity and atherogenesis. While it is still controversial about whether infectious pathogens contribute to cardiovascular diseases, direct genetic evidence indicates the importance of IL-1R/TLR signaling in atherogenesis. In this study, we examined the role of IRAK4 kinase activity in modified LDL-mediated signaling using bone marrow-derived macrophage as well as in vivo model of atherosclerosis. First, we found that the IRAK4 kinase activity was required for modified LDL-induced NFκB activation and expression of a subset of proinflammatory genes, but not for the activation of MAPKs in bonemarrow-derived macrophage. IRAK4 kinase inactive knock-in (IRAK4KI) mice were bred onto ApoE-/- mice to generate IRAK4KI/ApoE-/- mice. Importantly, the aortic sinus lesion formation was impaired in IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Furthermore, proinflammatory cytokine production was reduced in the aortic sinus region of IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Taken together, our results indicate that the IRAK4 kinase plays an important role in modified LDL-mediated signaling and the development of atherosclerosis, suggesting that pharmacological inhibition of IRAK4 kinase activity might be a feasible approach in the development of anti-atherosclerosis drugs. To identify global changes in gene expression, we examined gene expression profiles of macrophages from wild-type and IRAK4 kinase-inactive knock-in mice in response to acLDL stimulation using the Illumina microarray with probes for 23,000 transcripts. Bone marrow-derived macrophages from wild-type and IRAK4 kinase-inactive knock-in mice were treated with acLDL for 24 hours.
Project description:Atherosclerosis is a chronic inflammatory disease with high morbidity and mortality rates worldwide. Doublecortin-like kinase 1 (DCLK1), a microtubule-associated protein kinase, is involved in neurogenesis and human cancers. However, the role of DCLK1 in atherosclerosis remains undefined. In this study, we identified up-regulated DCLK1 in macrophages in atherosclerotic lesions of ApoE-/- mice fed an HFD and determined that macrophage-specific DCLK1 deletion attenuates atherosclerosis by reducing inflammation in mice. Mechanistically, RNA sequencing analysis indicated that DCLK1 mediates oxLDL-induced inflammation via NF-κB signaling pathway in primary macrophages. Co-immunoprecipitation followed by LC-MS/MS analysis identified IKKβ as a binding protein of DCLK1. We confirmed that DCLK1 directly interacts with IKKβ and phosphorylates IKKβ at S177/181, thereby facilitating subsequent NF-κB activation and inflammatory gene expression in macrophages. Finally, a pharmacological inhibitor of DCLK1 prevents atherosclerotic progression and inflammation both in vitro and in vivo. Our findings demonstrated that macrophage DCLK1 promotes inflammatory atherosclerosis by binding to IKKβ and activating IKKβ/NF-κB. This study reports DCLK1 as a new IKKβ regulator in inflammation and a potential therapeutic target for inflammatory atherosclerosis.
Project description:Atherosclerosis is a chronic inflammatory disease with high morbidity and mortality rates worldwide. Doublecortin-like kinase 1 (DCLK1), a microtubule-associated protein kinase, is involved in neurogenesis and human cancers. However, the role of DCLK1 in atherosclerosis remains undefined. In this study, we identified up-regulated DCLK1 in macrophages in atherosclerotic lesions of ApoE-/- mice fed an HFD and determined that macrophage-specific DCLK1 deletion attenuates atherosclerosis by reducing inflammation in mice. Mechanistically, RNA sequencing analysis indicated that DCLK1 mediates oxLDL-induced inflammation via NF-κB signaling pathway in primary macrophages. Co-immunoprecipitation followed by LC-MS/MS analysis identified IKKβ as a binding protein of DCLK1. We confirmed that DCLK1 directly interacts with IKKβ and phosphorylates IKKβ at S177/181, thereby facilitating subsequent NF-κB activation and inflammatory gene expression in macrophages. Finally, a pharmacological inhibitor of DCLK1 prevents atherosclerotic progression and inflammation both in vitro and in vivo. Our findings demonstrated that macrophage DCLK1 promotes inflammatory atherosclerosis by binding to IKKβ and activating IKKβ/NF-κB. This study reports DCLK1 as a new IKKβ regulator in inflammation and a potential therapeutic target for inflammatory atherosclerosis.
Project description:The NFM-NM-:B transcription factor is constitutively active in a number of hematologic and solid tumors, and many signaling pathways implicated in cancer are likely connected to NFM-NM-:B activation. A critical mediator of NFM-NM-:B activity is TGFM-NM-2-activated kinase 1 (TAK1). Here, we identify TAK1 as a novel interacting protein and direct target of fibroblast growth factor receptor 3 (FGFR3) tyrosine kinase activity. We further demonstrate that activating mutations in FGFR3 associated with both multiple myeloma and bladder cancer can modulate expression of genes which regulate NFM-NM-:B signaling, and promote both NFM-NM-:B transcriptional activity and cell adhesion in a manner dependent on TAK1 expression in both cancer cell types. Our findings suggest TAK1 as a potential therapeutic target for FGFR3-associated cancers, and other malignancies in which TAK1 contributes to constitutive NFM-NM-:B activation. A total of 12 samples of MGHU3 (Y375C) mutant FGFR3 bladder cancer cells (a kind gift from Dr. Margaret Knowles (University of Leeds, Leeds, UK)) were used for array-based gene expression analysis. 3 replicates of each condition: Control siRNA, Control siRNA + PD173074, TAK1 siRNA, and TAK1 siRNA + PD173074.
Project description:The transcription factor IRF5 is essential for immune defense against pathogens. Here, the authors show that the microtubule-associated factor GEF-H1 plays a critical role in host defense against Listeria monocytogenes in macrophages via activation of the IRF5 kinase IKKe
Project description:The NFκB transcription factor is constitutively active in a number of hematologic and solid tumors, and many signaling pathways implicated in cancer are likely connected to NFκB activation. A critical mediator of NFκB activity is TGFβ-activated kinase 1 (TAK1). Here, we identify TAK1 as a novel interacting protein and direct target of fibroblast growth factor receptor 3 (FGFR3) tyrosine kinase activity. We further demonstrate that activating mutations in FGFR3 associated with both multiple myeloma and bladder cancer can modulate expression of genes which regulate NFκB signaling, and promote both NFκB transcriptional activity and cell adhesion in a manner dependent on TAK1 expression in both cancer cell types. Our findings suggest TAK1 as a potential therapeutic target for FGFR3-associated cancers, and other malignancies in which TAK1 contributes to constitutive NFκB activation.
Project description:Exciting discoveries related to IL-1R/TLR signaling in development of atherosclerosis plaque have triggered intense interest in the molecular mechanisms by which innate immune signaling modulates the onset and development of atherosclerosis. Previous studies have clearly shown the definitive role of proinflammatory cytokine IL-1 in the development of atherosclerosis. Recent studies have provided direct evidence supporting a link between innate immunity and atherogenesis. While it is still controversial about whether infectious pathogens contribute to cardiovascular diseases, direct genetic evidence indicates the importance of IL-1R/TLR signaling in atherogenesis. In this study, we examined the role of IRAK4 kinase activity in modified LDL-mediated signaling using bone marrow-derived macrophage as well as in vivo model of atherosclerosis. First, we found that the IRAK4 kinase activity was required for modified LDL-induced NFκB activation and expression of a subset of proinflammatory genes, but not for the activation of MAPKs in bonemarrow-derived macrophage. IRAK4 kinase inactive knock-in (IRAK4KI) mice were bred onto ApoE-/- mice to generate IRAK4KI/ApoE-/- mice. Importantly, the aortic sinus lesion formation was impaired in IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Furthermore, proinflammatory cytokine production was reduced in the aortic sinus region of IRAK4KI/ApoE-/- mice compared to that in ApoE-/- mice. Taken together, our results indicate that the IRAK4 kinase plays an important role in modified LDL-mediated signaling and the development of atherosclerosis, suggesting that pharmacological inhibition of IRAK4 kinase activity might be a feasible approach in the development of anti-atherosclerosis drugs.
Project description:Microglial overactivation is actively involved in the pathogenesis of neurodegenerative diseases. Polo-like kinase 2 (PLK2) is a serine/threonine protein kinase associated with the regulation of synaptic plasticity and centriole duplication. Here, we identified PLK2 as an important early response gene in lipopolysaccharide (LPS)-stimulated microglial cells. Knockdown or inhibition of PLK2 remarkably attenuated LPS-induced expression of pro-inflammatory factors such as IL-1β, IL-6, COX2, TNF-α,and iNOS in microglial cells via suppressing the IKKβ-NF-κB signaling pathway.Notably, overexpression of PLK2 induced expression of pro-inflammatory factors and NF-κB transcriptional activation in the absence of inflammatory stimuli. Mechanistically,co-immunoprecipitation experiments revealed association between PLK2 and IKKβ, whereas GST pull-down assay showed no direct interaction between PLK2 and IKKβ. Proteomic analysis and in vitro kinase assay identified heat shock protein 90 alpha (HSP90α), a regulator of IKKβ activity, as a novel PLK2 substrate. Knockdown or pharmacological inhibition of HSP90α abolished PLK2-mediated activation of NF-κB transcriptional activity and microglial inflammatory activation. Furthermore,phosphoproteomic analysis pinpointed Ser252 and Ser263 on HSP90α as novel phosphorylation targets of PLK2. Subsequent functional studies demonstrated that re-expression of phosphor-dead mutation of these two phosphorylation sites on HSP90α failed to rescue the PLK2-induced activation of the NF-κB signaling. Lastly, conditional knockout of PLK2 in microglial cells dramatically ameliorated neuroinflammation and subsequent dopaminergic neuron loss in an intracranial LPS-induced mouse PD model. The present study revealed, for the first time, that PLK2 promoted microglial activation through the phosphorylation of HSP90α and subsequent activation of the IKKβ-NF-κB signaling pathway. Consequently, PLK2 emerges as a potential therapeutic target for the amelioration of neuroinflammation-related diseases.
Project description:Microglial overactivation is actively involved in the pathogenesis of neurodegenerative diseases. Polo-like kinase 2 (PLK2) is a serine/threonine protein kinase associated with the regulation of synaptic plasticity and centriole duplication. Here, we identified PLK2 as an important early response gene in lipopolysaccharide (LPS)-stimulated microglial cells. Knockdown or inhibition of PLK2 remarkably attenuated LPS-induced expression of pro-inflammatory factors such as IL-1β, IL-6, COX2, TNF-α, and iNOS in microglial cells via suppressing the IKKβ-NF-κB signaling pathway. Notably, overexpression of PLK2 induced expression of pro-inflammatory factors and NF-κB transcriptional activation in the absence of inflammatory stimuli. Mechanistically, co-immunoprecipitation experiments revealed association between PLK2 and IKKβ, whereas GST pull-down assay showed no direct interaction between PLK2 and IKKβ. Proteomic analysis and in vitro kinase assay identified heat shock protein 90 alpha (HSP90α), a regulator of IKKβ activity, as a novel PLK2 substrate. Knockdown or pharmacological inhibition of HSP90α abolished PLK2-mediated activation of NF-κB transcriptional activity and microglial inflammatory activation. Furthermore, phosphoproteomic analysis pinpointed Ser252 and Ser263 on HSP90α as novel phosphorylation targets of PLK2. Subsequent functional studies demonstrated that re-expression of phosphor-dead mutation of these two phosphorylation sites on HSP90α failed to rescue the PLK2-induced activation of the NF-κB signaling. Lastly, conditional knockout of PLK2 in microglial cells dramatically ameliorated neuroinflammation and subsequent dopaminergic neuron loss in an intracranial LPS-induced mouse PD model. The present study revealed, for the first time, that PLK2 promoted microglial activation through the phosphorylation of HSP90α and subsequent activation of the IKKβ-NF-κB signaling pathway. Consequently, PLK2 emerges as a potential therapeutic target for the amelioration of neuroinflammation-related diseases.