Project description:In order to unravel the role of the linear deubiquitinase OTULIN in LPS-induced gene expression in macrophages, we performed RNA-sequencing on primary bone marrow-derived macrophages of mice lacking OTULIN selectively in myeloid cells. Myeloid cell-specific OTULIN knock-out mice develop an auto-inflammatory phenotype and macrophages derived from these mice display increased LPS-induced inflammasome activation and cell death. Through analysing LPS-induced gene expression analyses on OTULIN-deficient macrophages we aimed to identify signalling pathways and genes that regulate inflammasome activation and cell death in these cells, in order to get new insights on the molecular events that regulate the development of autoinflammation in myeloid cell specific OTULIN-deficient mice.
Project description:The innate immune system recognizes nucleic acids as a signature of microbial infection and initiates host-protective responses, including the production of type I IFN and proinflammatory cytokines. Z-DNA binding protein 1 (ZBP1, also known as DLM-1 or DAI) was previously identified as a dsDNA binding protein, triggering DNA-mediated activation of innate immune responses. However, mice or cells lacking ZBP1 produce normal levels of type I IFN in response to dsDNA. Therefore, the classification of ZBP1 as a true DNA sensor remains to be resolved. Here, we report that the single stranded RNA virus, influenza A virus (IAV) is a trigger of the cytosolic sensor ZBP1. Sensing of IAV infection by ZBP1 engages a novel NLRP3 inflammasome pathway that is not defined by the conventions of the canonical and non-canonical NLRP3 inflammasome pathways. Surprisingly, IAV-induced cell death was not prevented by the absence of the NLRP3 inflammasome. Instead, we identified parallel contributions from pyroptosis, necroptosis and apoptosis in the execution of ZBP1-dependent cell death, mediated by the kinase RIPK3. Overall, the ability of ZBP1 to sense IAV infection signifies a point of divergence for IAV-induced programmed cell death pathways and inflammasome activation. We used microarrays to explore the gene expression profiles differentially expressed in influenza-infected bone marrow derived macrophages (BMDM) isolated from Ifnar1-/- and wild-type mice.
Project description:The pediatric immune deficiency X-linked proliferative disease-2 (XLP-2) is a unique disease, with patients presenting with either hemophagocytic lymphohistiocytosis (HLH) or intestinal bowel disease (IBD). Interestingly, XLP-2 patients display high levels of IL-18 in the serum even while in stable condition, presumably through spontaneous inflammasome activation. Recent data suggests that LPS stimulation can trigger inflammasome activation through a TNFR2/TNF/TNFR1 mediated loop in xiap−/− macrophages. Yet, the direct role TNFR2-specific activation plays in the absence of XIAP is unknown. We found TNFR2-specific activation leads to cell death in xiap−/− myeloid cells, particularly in the absence of the RING domain. RIPK1 kinase activity downstream of TNFR2 resulted in a TNF/TNFR1 cell death, independent of necroptosis. TNFR2-specific activation leads to a similar inflammatory NF-kB driven transcriptional profile as TNFR1 activation with the exception of upregulation of NLRP3 and caspase-11. Activation and upregulation of the canonical inflammasome upon loss of XIAP was mediated by RIPK1 kinase activity and ROS production. While both the inhibition of RIPK1 kinase activity and ROS production reduced cell death, as well as release of IL-1β, the release of IL-18 was not reduced to basal levels. This study supports targeting TNFR2 specifically to reduce IL-18 release in XLP-2 patients and to reduce priming of the inflammasome components.
Project description:Francisella are pathogenic bacteria whose virulence is linked to their ability to replicate within the host cell cytosol. Entry into the macrophage cytosol activates a host protective multimolecular complex called the inflammasome to release the proinflammatory cytokines IL-1 and IL-18 and trigger caspase-1 dependent cell death. Here we show that cytosolic Francisella induce a type I interferon (IFN) response that is essential for caspase-1 activation, inflammasome mediated cell death, and release of IL-1 and IL-18. Extensive type I IFN dependent cell death resulting in macrophage depletion occurs in vivo during Francisella infection. Type I IFN is also necessary for inflammasome activation in response to cytosolic Listeria but not vacuole localized Salmonella or extracellular ATP. These results show the specific connection between type I IFN signaling and inflammasome activation, two sequential events triggered by recognition of cytosolic bacteria. To our knowledge, this is the first example of positive regulation of inflammasome activation. This connection underscores the importance of cytosolic recognition of pathogens and highlights how multiple innate immunity pathways interact before commitment to critical host responses. Keywords: murine macrophage response to Francisella tularensis subspecies novicida infection We analyzed a series of 18 MEEBO arrays on which were hybed RNA randomly amplified from bone marrow derived macrophages infected or not with WT Francisella tularensis subspecies novicida or a the mglA mutant strain GB2.
Project description:Solute carrier family 7 member 11 (SLC7A11; also known as xCT) is a cystine transporter frequently overexpressed in cancers. Cancer cells with high expression of SLC7A11 (SLC7A11high) are resistant to ferroptosis but exquisitely sensitive to glucose deprivation-induced cell death, although the underlying mechanism of the latter cell death remains poorly understood. Here we show that
We found that glucose deprivation induced a novel type of cell death in SLC7A11high cancer cells that was different from apoptosis or ferroptosis. And the bioorthogonal chemical proteomics analysis revealed that a large amount of actin cytoskeleton proteins were shown with significantly dysregulated disulfides induced by glucose starvation in SLC7A11high cancer cells. In mechanism, SLC7A11high mediated cystine uptake and subsequent reduction to cysteine forced disulfide stress on actin cytoskeleton upon glucose deprivation through draining intracellular reduced nicotinamide adenine dinucleotide phosphate (NADPH) pool, which was independent of generating reactive oxygen species (ROS). The disulfide stress on the actin cytoskeleton induced rapidly contracted actin filaments and detached from the plasma membrane, which incurred cell death. In the end, using whole-genome CRISPR/Cas9 knock-out screening we identified NCKAP1 as a downstream factor of SLC7A11 to promoting cell death upon glucose deprivation by inhibiting branched actin filaments.