Project description:Macrophage activation by bacterial lipopolysaccharides (LPS) is induced through Toll-like receptor 4 (TLR4). The synthesis and activity of TLR4 downstream signalling molecules modulates the expression of pro- and anti-inflammatory cytokines. To address the impact of post-transcriptional regulation on that process, we performed RIP-Chip analysis. Differential association of mRNAs with heterogeneous ribonucleoprotein K (hnRNP K), an mRNA-specific translational regulator in differentiating haematopoietic cells, was studied in non-induced and LPS-activated macrophages. Analysis of interactions affected by LPS revealed an enrichment of mRNAs encoding TLR4 downstream kinases and their modulators. We focused on transforming growth factor β activated kinase-1 (TAK1), a central player in TLR4 signalling. HnRNP K interacts specifically with a sequence in the TAK1 mRNA 3' UTR in vitro. Silencing of hnRNP K does not affect TAK1 mRNA synthesis and stability, but enhances TAK1 mRNA translation, resulting in elevated TNF-alpha, IL-1beta and IL-10 mRNA expression. Our data suggest that the hnRNP K-3' UTR complex inhibits TAK1 mRNA translation in non-induced macrophages. LPS-dependent TLR4 activation abrogates translational repression and newly synthesised TAK1 initiates the inflammatory response of macrophages. In this dataset, we include expression data of RAW 264.7 cells comparing untreated cells and 6h Lipopolysaccharide treatment, and analyse RNAs co-precipitating with hnRNP K dependent on LPS treatment. 12 total samples were analyzed, 6 samples of 2 biological replicates.
Project description:Macrophage activation by bacterial lipopolysaccharides (LPS) is induced through Toll-like receptor 4 (TLR4). The synthesis and activity of TLR4 downstream signalling molecules modulates the expression of pro- and anti-inflammatory cytokines. To address the impact of post-transcriptional regulation on that process, we performed RIP-Chip analysis. Differential association of mRNAs with heterogeneous ribonucleoprotein K (hnRNP K), an mRNA-specific translational regulator in differentiating haematopoietic cells, was studied in non-induced and LPS-activated macrophages. Analysis of interactions affected by LPS revealed an enrichment of mRNAs encoding TLR4 downstream kinases and their modulators. We focused on transforming growth factor β activated kinase-1 (TAK1), a central player in TLR4 signalling. HnRNP K interacts specifically with a sequence in the TAK1 mRNA 3' UTR in vitro. Silencing of hnRNP K does not affect TAK1 mRNA synthesis and stability, but enhances TAK1 mRNA translation, resulting in elevated TNF-alpha, IL-1beta and IL-10 mRNA expression. Our data suggest that the hnRNP K-3' UTR complex inhibits TAK1 mRNA translation in non-induced macrophages. LPS-dependent TLR4 activation abrogates translational repression and newly synthesised TAK1 initiates the inflammatory response of macrophages. In this dataset, we include expression data of RAW 264.7 cells comparing untreated cells and 6h Lipopolysaccharide treatment, and analyse RNAs co-precipitating with hnRNP K dependent on LPS treatment.
Project description:Caspase-8 modulates TLR-induced gene transcription, which is only partially dependent on caspase-8 catalytic activity. Moreover, The slow kinetics of IFNγ and LPS-induced BMDM killing offers the possibility that transcriptional responses may contribute to cell death activation. We performed 3' mRNA-sequencing to examine whether caspase-8 might contribute, at least in part, to IFNγ and LPS-triggered macrophage death via its transcriptional role. We found that caspase-8-mediated transcriptional re-programming of BMDMs. Importantly, caspase-8 modulates expression of Bcl-2 family members and inducible nitric oxide synthase (iNOS) to promote activation of the mitochondrial apoptotic effectors, BAX and BAK.
Project description:Negative regulation of immunoreceptor signaling is required for preventing hyperimmune activation and maintaining immune homeostasis. The roles of p38IP in immunoreceptor signaling remain unclear. Here, we show that p38IP suppresses T cell receptor (TCR)/LPS-activated NF-κB and p38 by targeting TAK1 kinase and that p38IP protein levels are downregulated in human-PBMCs from rheumatoid arthritis (RA) patients, inversely correlating with the enhanced activity of NF-κB and p38. Mechanistically, p38IP interacts with TAK1 to disassemble the TAK1-TAB (TAK1-binding protein) complex. p38IP overexpression decreases TCR-induced binding of K63-linked polyubiquitin (polyUb) chains to TAK1 but increases that to TAB2, and p38IP knockdown shows the opposite effects, indicating unanchored K63-linked polyUb chain transfer from TAB2 to TAK1. p38IP dynamically interacts with TAK1 upon stimulation, because of the higher binding affinity of TAK1 and p38IP for sequential polyUb binding by TAB2 and TAK1, respectively. Moreover, p38IP specifically scaffolds the deubiquitinase USP4 to deubiquitinate TAK1 once TAK1 is activated. These findings reveal a novel role and the mechanisms of p38IP in controlling TCR/LPS signaling and suggest that p38IP might participate in RA pathogenesis.
Project description:IFN-g primes macrophages for enhanced inflammatory activation by TLRs and microbial killing, but little is known about the regulation of cell metabolism or mRNA translation during priming. We found that IFN-g regulates macrophage metabolism and translation in an integrated manner by targeting mTORC1 and MNK pathways that converge on the selective regulator of translation initiation eIF4E. Physiological downregulation of the central metabolic regulator mTORC1 by IFN-g was associated with autophagy and translational suppression of repressors of inflammation such as HES1. Genome-wide ribosome profiling in TLR2-stimulated macrophages revealed that IFN-g selectively modulates the macrophage translatome to promote inflammation, further reprogram metabolic pathways, and modulate protein synthesis. These results add IFN-g-mediated metabolic reprogramming and translational regulation as key components of classical inflammatory macrophage activation. RPF and RNAseq libraries were generated from mock or IFN-g-primed human macrophages. Cells were stimulated with Pam3Cys and harvested at 4 hours. Libraries were generated using protocol modified from Illumina Truseq technology.
Project description:IFN-g primes macrophages for enhanced inflammatory activation by TLRs and microbial killing, but little is known about the regulation of cell metabolism or mRNA translation during priming. We found that IFN-g regulates macrophage metabolism and translation in an integrated manner by targeting mTORC1 and MNK pathways that converge on the selective regulator of translation initiation eIF4E. Physiological downregulation of the central metabolic regulator mTORC1 by IFN-g was associated with autophagy and translational suppression of repressors of inflammation such as HES1. Genome-wide ribosome profiling in TLR2-stimulated macrophages revealed that IFN-g selectively modulates the macrophage translatome to promote inflammation, further reprogram metabolic pathways, and modulate protein synthesis. These results add IFN-g-mediated metabolic reprogramming and translational regulation as key components of classical inflammatory macrophage activation. microRNA-seq libraries were generated from mock or IFN-g-primed human macrophages. Cells were stimulated with or without Pam3Cys and harvested at 4 hours Libraries were generated using Illumina Truseq small RNA technology.
Project description:To investigate the plasticity of Lipolysaccharide (LPS) tolerance, we employed microarray profiling to analyse the gene expression profile in macrophage. Four macrophage populations were induced; Untreated macrophages (Control group), Acute response to LPS (LPS activation group), LPS tolerance (T – Tolerant group) and recovered (R = recovered macrophage group) Using transcriptional analysis we demonstrate that recovery from LPS tolerance (R – Recovery), as defined by cytokine gene expression, is associated with a global change in the transcriptional profile of macrophage. This data confirms that LPS tolerance is a transient state which results in induction of novel hybrid macrophage activation state with a unique transcriptional signature. Bone marrow derived macrophages were polarised into three activation states; Acute response to LPS (A), LPS tolerant (T) and recovered (R). Gene expression was measured at 4 hours post stimulation with LPS. Three independent experiments were performed to measure gene expression changes between each macrophage group.
Project description:To investigate the plasticity of Lipolysaccharide (LPS) tolerance, we employed microarray profiling to analyse the gene expression profile in macrophage. Four macrophage populations were induced; Untreated macrophages (Control group), Acute response to LPS (LPS activation group), LPS tolerance (T – Tolerant group) and recovered (R = recovered macrophage group) Using transcriptional analysis we demonstrate that recovery from LPS tolerance (R – Recovery), as defined by cytokine gene expression, is associated with a global change in the transcriptional profile of macrophage. This data confirms that LPS tolerance is a transient state which results in induction of novel hybrid macrophage activation state with a unique transcriptional signature.
Project description:Remodeling of the tricarboxylic acid (TCA) cycle is a metabolic adaptation mechanism accompanying inflammatory macrophage activation. During this process, endogenous metabolites can adopt regulatory roles that govern specific aspects of inflammatory response, as recently shown for succinate, which regulates the downstream pro-inflammatory IL-1β-HIF1a axis. Itaconate is one of the most highly induced metabolites in activated macrophages, yet its functional significance remains unknown. Here, we show that itaconate modulates macrophage metabolism and effector functions via its effect on succinate dehydrogenase, by inhibiting conversion of succinate to fumarate. Through this action, itaconate exerts anti-inflammatory effects when administered in vitro and in vivo during macrophage activation and ischemia-reperfusion injury. Using newly generated Irg1-/- mice, which lack the ability to produce itaconate, we show that endogenous itaconate regulates succinate levels and function, changes in mitochondrial respiration, and inflammatory cytokine production during macrophage activation. These studies highlight itaconate as a major physiological regulator of the global metabolic rewiring and effector functions of inflammatory macrophages. Experiment 1: mature WT BMDM were treated for 12h with 0.25 mM dimethyl itaconate (DI) or vehicle (Unst) and then stimulated with LPS (E. coli 0111:B4; 100 ng/ml, 4h) (DI+LPS; LPS); Experiment 2: mature Irg1-/- BMDM were stimulated with LPS (E. coli 0111:B4; 100 ng/ml) and murine recombinant IFNg (50 ng/ml) for 24h.
Project description:When macrophages encounter pathogens, they transiently induce an orchestrated cascade of pro- and anti-inflammatory genes. To obtain a precise picture of transcriptome-wide mRNA expression patterns, we performed RNA-Seq of total RNA at a high temporal resolution during the first two hours of macrophage activation. We systematically analyzed the contribution of translational regulation to the early phase of macrophage activation. While the expression of most cytokines is pre-dominanatly regulated by changes in mRNA levels, de-repression of translation was found to permit expression of many feedback inhibitors of the inflammatory response. Expression profiles of LPS-treated Raw264.7 cells (0, 15, 30, 45, 60, 75, 90 and 120 min after stimulation) were generated by deep sequencing using Illumina HiSeq 2000.