Project description:Alterations in Lpin2 encoding the phosphatidate phosphatase Lipin2 cause the autoinflammatory disorder Majeed syndrome. Lipin2 deficiency enhances lipopolysaccharide (LPS)-induced NLRP3 inflammasome formation in macrophages.
Project description:Overnutrition leads to metabolic disorders such as obesity and diabetes. Enhanced inflammation has also been shown to be an essential player in the progression of metabolic diseases. However, how immune cells sense nutritional status and contribute to whole-body metabolism remain largely elusive. OGT-catalyzed protein O-GlcNAcylation is thought to be a metabolic sensor that modulates cell signaling. In this study, we show that overnutrition stimulates macrophage O-GlcNAc signaling. O-GlcNAc signaling suppresses macrophage proinflammatory activation and protects against diet-induced obesity and metabolic dysfunction. These findings thus identify macrophage O-GlcNAc signaling as a novel homeostatic regulator at the interface of inflammation and metabolism.
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: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.
Project description:Shiga toxins (Stxs) are bacterial cytotoxins produced by the enteric pathogens Shigella dysenteriae serotype 1 and some serotypes of Escherichia coli that cause bacillary dysentery and hemorrhagic colitis, respectively. To date, approaches to studying the capacity of Stxs to alter gene expression in intoxicated cells have been limited to individual genes. However, it is known that many of the signaling pathways activated by Stxs regulate the expression of multiple genes in mammalian cells. To expand the scope of analysis of gene expression and to better understand the underlying mechanisms for the various effects of Stxs on cell functions, we carried out comparative microarray analyses to characterize the global transcriptional response of human macrophage-like THP-1 cells to Shiga toxin type 1 (Stx1) and LPS. Data were analyzed using a rigorous combinatorial approach with three separate statistical algorithms. Thirty-six genes met the criteria of up-regulated expression in response to Stx1 treatment with 14 genes uniquely up-regulated by Stx1. Microarray data were validated by real time RT-PCR for genes encoding Egr-1 (transcriptional regulator), COX-2 (inflammation), and DUSP1, 5 and 10 (regulation of MAPK signaling). Stx1-mediated signaling through ERK1/2 and Egr-1 appears to be involved in the increased expression of the proinflammatory mediator TNF-α. Activation of COX-2 expression is associated with the increased production of proinflammatory and vasoactive eicosanoids. However, the capacity of Stx1 to increase the expression of genes encoding phosphatases suggests that mechanisms to dampen the macrophage proinflammatory response may be built into host response to the toxins. Three separate experiments were performed for each of three treatment types: 3 untreated controls, 3 Stx-1 treated cell (400 ng/ml for 6h), 3 LPS-stimulated cells (200 ng/ml for 6h). Total RNA was isolated, processexc, and hybridized to a total of 9 Affymetrix human HG U133 arrays.