Project description:Activation of the STING (Stimulator of Interferon Genes) pathway by microbial or self-DNA, as well as cyclic di nucleotides (CDN), results in the induction of numerous genes that suppress pathogen replication and facilitate adaptive immunity. However, sustained gene transcription is rigidly prevented to avoid lethal STING-dependent pro-inflammatory disease by mechanisms that remain unknown. We demonstrate here that after autophagy-dependent STING delivery of TBK1 (TANK-binding kinase 1) to endosomal/lysosomal compartments and activation of transcription factors IRF3 (interferon regulatory factors 3) and NF-κB (nuclear factor kappa beta), that STING is subsequently phosphorylated by serine/threonine UNC-51-like kinase (ULK1/ATG1) and IRF3 function is suppressed. ULK1 activation occurred following disassociation from its repressor adenine monophosphate activated protein kinase (AMPK), and was elicited by CDN’S generated by the cGAMP synthase, cGAS. Thus, while CDN’s may initially facilitate STING function, they subsequently trigger negative-feedback control of STING activity, thus preventing the persistent transcription of innate immune genes. Total RNA obtained from primary STING deficient mouse embryonic fibroblast reconstituted with mSTING (W), S365A variant (A), or S365D variant (D). These cells were transfected with dsDNA (ISD) for 3 hours.
Project description:Activation of the STING (Stimulator of Interferon Genes) pathway by microbial or self-DNA, as well as cyclic di nucleotides (CDN), results in the induction of numerous genes that suppress pathogen replication and facilitate adaptive immunity. However, sustained gene transcription is rigidly prevented to avoid lethal STING-dependent pro-inflammatory disease by mechanisms that remain unknown. We demonstrate here that after autophagy-dependent STING delivery of TBK1 (TANK-binding kinase 1) to endosomal/lysosomal compartments and activation of transcription factors IRF3 (interferon regulatory factors 3) and NF-κB (nuclear factor kappa beta), that STING is subsequently phosphorylated by serine/threonine UNC-51-like kinase (ULK1/ATG1) and IRF3 function is suppressed. ULK1 activation occurred following disassociation from its repressor adenine monophosphate activated protein kinase (AMPK), and was elicited by CDN’S generated by the cGAMP synthase, cGAS. Thus, while CDN’s may initially facilitate STING function, they subsequently trigger negative-feedback control of STING activity, thus preventing the persistent transcription of innate immune genes.
Project description:Cyclic dinucleotides serve as bacterial secondary messengers regulating sporulation, motility, biofilm formation and virulence. A nonsymmetric c-di-GAMP is firstly identified in bacteria to promote colonization, while mammalian 2’3’-cGAMP is synthesized by cGAS through binding and activating STING to trigger innate immune activation. However, pathophysiological function of 2’3’-cGAMP beyond innate immunity remains elusive. Here, we report 2’3’-cGAMP facilitates cell migration independent of STING and its innate immune function. 2’3’-cGAMP interactome analysis with a targeted shRNA-screen identifies the GTPase Rab18 as a direct 2’3’-cGAMP binding partner and effector in cell migration control. Mechanistically, 2’3’-cGAMP binds Rab18-S17, E36 and R92 residues to facilitate Rab18 activation and subsequently promotes FosB transcription in promoting cell migration. Low-dose doxorubicin induces 2’3’-cGAMP synthesis and facilitates cell migration in vitro and in vivo. Interestingly, lovastatin induces Rab18 phosphorylation abolishes 2’3’-cGAMP recognition to antagonize 2’3’-cGAMP induced cell migration. Together, our study reveals a novel 2’3’-cGAMP function in cell migration control beyond innate immunity via binding Rab18 that provides new insights into clinical applications of 2’3’-cGAMP.
Project description:The ability of dying cells to activate antigen presenting cells (APCs) is carefully controlled to avoid unwarranted inflammatory responses. Here we show that engulfed cells only containing cytosolic dsDNA species (viral or synthetic) or cyclic di-nucleotides (CDNs) are able to stimulate APCs, via extrinsic STING-signaling. HEK293 cells containing double strand DNA robustly induced the production of cytokines in macrophages that was dependent on extrinsic STING signaling within the macrophage.
Project description:STING is an intracellular sensor of cyclic di-nucleotides involved in response to pathogen- or self-derived DNA that induces protective immunity, or if dysregulated, autoimmunity. STING trafficking is tightly linked to its activity. We aimed to systematically characterize genes regulating STING trafficking and to define their impact on STING responses. Based on proximity-ligation proteomics and genetic screens, an ESCRT complex containing HGS, VPS37A and UBAP1 was found to be required for STING degradation and signaling shutdown. Oligomerization-driven STING ubiquitination by UBE2N formed a platform for ESCRT recruitment at the endosome, responsible for STING signaling shutdown. A UBAP1 mutant that underlies human spastic paraplegia and disrupts ESCRT function led to STING-dependent type I IFN responses at the steady-state, defining ESCRT as a homeostatic regulator of STING signaling.
Project description:Upon systemic bacterial infection, hematopoietic stem and progenitor cells (HSPCs) migrate to the periphery in order to supply a sufficient number of immune cells. Although pathogen-associated molecular patterns (PAMPs) reportedly mediate HSPC activation, how HSPCs detect pathogen invasion in vivo remains elusive. Bacteria use the second messenger bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) for a variety of activities. Here we report that c-di-GMP comprehensively regulates both HSPCs and their niche cells through an innate immune sensor, STING, thereby inducing entry into the cell cycle and mobilization of HSPCs, while decreasing the number and repopulation capacity of long-term hematopoietic stem cells (LT-HSCs). Furthermore, we show that type I IFN acts as a downstream target of c-di-GMP to inhibit HSPC expansion in the spleen, while TGF-β1 is required for c-di-GMP-dependent splenic HSPC expansion. Our results define novel machinery underlying dynamic regulation of HSPCs and their niches during bacterial infection through c-di-GMP/STING signaling. Ten-week-old mice were intraperitoneally administered PBS or 200 nmol c-di-GMP, and CD150+ CD41- CD48- CD34- Flt3- LSK cells of pooled bone marrow from 10 mice per group were sorted 3 days later. mRNA was then extracted using RNeasy micro (Qiagen). Likewise, CD45- Ter-119- CD31- CD140a+ CD51+ MSCs and CD45- Ter119- CD31+ endothelial cells from c-di-GMP-treated or untreated mice were sorted and mRNA was extracted. cDNA was synthesized from mRNA and hybridized to gene chip Mouse60k (Agilent Technologies) and expression levels analyzed.
Project description:Dendritic cells are the initiators of the adaptive immune response, therefore its gene expression allow us to predict the responses to vaccination. We used bone marrow derived dendritic cells (BMDC) to analyze the gene expression that result from the exposure to adjuvants. We use model antigen OVA and cyclic di-AMP (CDA) as an adjuvant in order to characterize the genes involved in the activation of dendritic cells by CDA alone or when the antigen is present. Cyclic di-nucleotides (CDN) are potent stimulators of innate and adaptive immune responses. Cyclic di-AMP (CDA) is a promising adjuvant that generates humoral and cellular immunity. The strong STING-dependent stimulation of type I IFN represents a key feature of CDA. However, recent studies suggested that this is dispensable for adjuvanticity. Here we demonstrate that stimulation of IFN-γ-secreting CD8+ cytotoxic T lymphocytes (CTL) is significantly decreased after vaccination in the absence of type I IFN signaling. The biological significance of this CTL response was confirmed by the stimulation of MHC class I-restricted protection against influenza virus challenge. We show here that type I IFN (and not TNF-α) is essential for CDA-mediated cross-presentation by a cathepsin independent, TAP and proteosome dependent cytosolic antigen processing pathway, which promotes effective cross-priming and further CTL induction. Our data clearly demonstrate that type I IFN signaling is critical for CDN-mediated cross-presentation
Project description:Upon systemic bacterial infection, hematopoietic stem and progenitor cells (HSPCs) migrate to the periphery in order to supply a sufficient number of immune cells. Although pathogen-associated molecular patterns (PAMPs) reportedly mediate HSPC activation, how HSPCs detect pathogen invasion in vivo remains elusive. Bacteria use the second messenger bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) for a variety of activities. Here we report that c-di-GMP comprehensively regulates both HSPCs and their niche cells through an innate immune sensor, STING, thereby inducing entry into the cell cycle and mobilization of HSPCs, while decreasing the number and repopulation capacity of long-term hematopoietic stem cells (LT-HSCs). Furthermore, we show that type I IFN acts as a downstream target of c-di-GMP to inhibit HSPC expansion in the spleen, while TGF-β1 is required for c-di-GMP-dependent splenic HSPC expansion. Our results define novel machinery underlying dynamic regulation of HSPCs and their niches during bacterial infection through c-di-GMP/STING signaling.
Project description:The innate immune system responds to unique molecular signatures that are widely conserved among microbes but that are not normally present in host cells. Compounds that stimulate innate immune pathways may be valuable in the design of novel adjuvants, vaccines, and other immunotherapeutics.The cyclic dinucleotide cyclic-di-guanosine monophosphate (c-di-GMP) is a recently appreciated second messenger that plays critical regulatory roles in many species of bacteria but is not produced by eukaryotic cells. In vivo and in vitro studies have previously suggested that c-di-GMP is a potent immunostimulatory compound recognized by mouse and human cells. Here we provide evidence that c-di-GMP is sensed in the cytosol of mammalian cells via a novel immunosurveillance pathway. The potency of cytosolic signaling induced by cyclic-di- GMP is comparable to that induced by cytosolic delivery of DNA, and both nucleic acids induce a similar transcriptional profile, including triggering of type I interferons and coregulated genes via induction of TBK1, IRF3, NF-!B and MAP kinases. However, the cytosolic pathway that senses c-di-GMP appears to be distinct from all known nucleic acid-sensing pathways.Our results suggest a novel mechanism by which host cells can induce an inflammatory response to a widely produced bacterial ligand. Three-condition experiment: macrophages transfected with mono-GMP (negative control), double-stranded DNA (positive control), or cyclic-di-GMP (experimental condition). Biological replicates: two, independently treated, harvested, and hybridized to arrays. One replicate per array, except two technical replicates were performed for one of the positive control samples.
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from DMBA or acetone treated wild type (WT) or STING deficient (SKO) mouse skin or skin tumor was examined for gene expression.