Project description:Nrf2 (NF-E2-related factor-2) transcription factor regulates oxidative/xenobiotic stress response and also represses inflammation. However, the mechanisms how Nrf2 alleviates inflammation are still unclear. Here, we demonstrate that Nrf2 interferes with lipopolysaccharide-induced transcriptional upregulation of proinflammatory cytokines, including IL-6 and IL-1β. ChIP-seq and ChIP-qPCR analyses revealed that Nrf2 binds to the proximity of these genes in macrophages and inhibits RNA Pol II recruitment. Further, we found that Nrf2-mediated inhibition is independent of the Nrf2 binding motif and reactive oxygen species level. Murine inflammatory models further demonstrated that Nrf2 interferes with IL6 induction and inflammatory phenotypes in vivo. Thus, contrary to the widely accepted view that Nrf2 suppresses inflammation through redox control, we demonstrate here that Nrf2 opposes transcriptional upregulation of proinflammatory cytokine genes. This study identifies Nrf2 as the upstream regulator of cytokine production and establishes a molecular basis for an Nrf2-mediated anti-inflammation approach. Gene expression in BMDMs obtained from wild-type and Keap1-CKO mice. In Keap1-CKO (Keap1 flox/flox::LysM-Cre) BMDMs, Nrf2 transcription factor is activated due to Keap1-deficiency. BMDMs were obtained by a culture of bone marrow cells in the presence of M-CSF for7 days. M1-activated BMDMs were obtained by stimulation with LPS and IFNg for 6 hours, while M2-activated BMDMs were obtained by a stimulation with IL-4 for 6 hours. Two independent BMDM cultures were performed, and each experiment contains samples obtained from one wild-type and one Keap1-CKO mice, respectively.
Project description:HOIL-1L is an essential member of the linear ubiquitin assembly complex (LUBAC), which targets Nemo for linear ubiquitination during NF-kB activation in response to a variety of simuli, including LPS and TNFa treatment. HOIL-1L has also been suggested to function as a transcription factor. Here we analyzed changes in the global transcriptional profiles of primary bone marrow derived macrophage (BMDMs) from WT and HOIL-1L-/- mice upon treatment with NF-kB activating simuli. BMDMs were differentiated for 1 week and then treated with mock (untreated), 10ng/ml LPS, or 1ng/ml TNFa for 4 hours. RNA was immediately collected and analyzed in biological duplicates by the Agilent 8x60 mouse array.
Project description:Reticuloendothelial macrophages engulf ~0.2 trillion senescent erythrocytes daily in a process called erythrophagocytosis (EP). This critical mechanism preserves systemic heme-iron homeostasis by regulating red blood cell (RBC) catabolism and iron recycling. Although extensive work has demonstrated the various effects on macrophage metabolic reprogramming by stimulation with proinflammatory cytokines, little is known about the impact of EP on the macrophage metabolome and proteome. Thus, we performed mass spectrometry-based metabolomics and proteomics analyses of bone marrow-derived macrophages (BMDMs) before and after EP of IgG-coated RBCs. Further, metabolomics was performed on BMDMs incubated with free IgG to ensure that changes to macrophage metabolism were due to opsonized RBCs and not to free IgG binding. Uniformly labeled tracing experiments were conducted on BMDMs in the presence and absence of IgG-coated RBCs to assess the flux of glucose through the pentose phosphate pathway (PPP). In this study, we demonstrate that EP significantly alters amino acid and fatty acid metabolism, the Krebs cycle, OXPHOS, and arachidonate-linoleate metabolism. Increases in levels of amino acids, lipids and oxylipins, heme products, and RBC-derived proteins are noted in BMDMs following EP. Tracing experiments with U-13C6 glucose indicated a slower flux through glycolysis and enhanced PPP activation. Notably, we show that it is fueled by glucose derived from the macrophages themselves or from the extracellular media prior to EP, but not from opsonized RBCs. The PPP-derived NADPH can then fuel the oxidative burst, leading to the generation of reactive oxygen species necessary to promote digestion of phagocytosed RBC proteins via radical attack. Results were confirmed by redox proteomics experiments, demonstrating the oxidation of Cys152 and Cys94 of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and hemoglobin-β, respectively. Significant increases in early Krebs cycle and C5-branched dibasic acid metabolites (α-ketoglutarate and 2-hydroxyglutarate, respectively) indicate that EP promotes the dysregulation of mitochondrial metabolism. Lastly, EP stimulated aminolevulinic acid (ALA) synthase and arginase activity as indicated by significant accumulations of ALA and ornithine after IgG-mediated RBC ingestion. Importantly, EP-mediated metabolic reprogramming of BMDMs does not occur following exposure to IgG alone. In conclusion, we show that EP reprograms macrophage metabolism and modifies macrophage polarization.
Project description:GPS2 binding sites in BMDMs can be localized specially in enhancers (H3K27ac) and promoters (H3K27ac, H3K4me3). Upon GPS2 knock-out in BMDMs, de-repression of certain inflammatory genes occur, as accompanied by increased recruitment of H3K27ac and H3K4me3 marks.
Project description:Macrophages play critical roles in inflammation and tissue homeostasis, and their functions are regulated by various autocrine, paracrine, and endocrine factors. We have previously shown that CTRP6, a secreted protein of the C1q family, targets both adipocytes and macrophages to promote obesity-linked inflammation in adipose tissue. However, the gene programs and signaling pathways directly regulated by CTRP6 in macrophage remain unknown. Here, we combine transcriptomic and phosphoproteomic analyses to show that CTRP6 activates inflammatory gene programs and signaling pathways in bone marrow-derived macrophages (BMDMs). Treatment of BMDMs with CTRP6 upregulates proinflammatory, and suppresses the anti-inflammatory, gene expression. We show that CTRP6 activates p44/42-MAPK, p38-MAPK, and NF-κB signalings to promote inflammatory cytokine secretion from BMDMs, and that pharmacologic inhibition of these signaling pathways largely abolish the effects of CTRP6. Pretreatment of BMDMs with CTRP6 further augments LPS-induced inflammatory signaling and cytokine secretion from BMDMs. Consistent with the metabolic phenotype of proinflammatory M1-like macrophages, CTRP6 treatment induces a shift toward aerobic glycolysis and lactate production, reduces oxidative metabolism, and elevates mitochondrial ROS production in BMDMs. We use a Ctrp6 knockout mouse model to further confirm the physiologic relevance of our in vitro findings. BMDMs from CTRP6-deficient mice are less inflammatory at baseline and show a marked suppression of LPS-induced inflammatory gene expression and cytokine secretion. Loss of CTRP6 in mice also dampens LPS-induced inflammation and hypothermia. Collectively, we provide mechanistic evidence that CTRP6 regulates macrophage function, and neutralizing CTRP6 activity may have beneficial effects in reducing inflammation.
Project description:Here we show that the RNA-binding protein CPEB4 sustains the expression of anti-inflammatory factors in LPS-stimulated BMDMs, by binding to the corresponding mRNAs and promoting their stabilization. in macrophages.
Project description:This experiement aims to know what the differences of protein translation are in the bone marrow derived macro-phages(BMDMs) from WT mice and Elp3 KO mice. We treated the BMDMs with or without IL-4 for 4 hours.