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Microbiota triggers STING-type I IFN-dependent monocyte reprogramming of the tumor microenvironment.Cell Oct 2021The tumor microenvironment (TME) influences cancer progression and therapy response. Therefore, understanding what regulates the TME immune compartment is vital. Here we...
The tumor microenvironment (TME) influences cancer progression and therapy response. Therefore, understanding what regulates the TME immune compartment is vital. Here we show that microbiota signals program mononuclear phagocytes in the TME toward immunostimulatory monocytes and dendritic cells (DCs). Single-cell RNA sequencing revealed that absence of microbiota skews the TME toward pro-tumorigenic macrophages. Mechanistically, we show that microbiota-derived stimulator of interferon genes (STING) agonists induce type I interferon (IFN-I) production by intratumoral monocytes to regulate macrophage polarization and natural killer (NK) cell-DC crosstalk. Microbiota modulation with a high-fiber diet triggered the intratumoral IFN-I-NK cell-DC axis and improved the efficacy of immune checkpoint blockade (ICB). We validated our findings in individuals with melanoma treated with ICB and showed that the predicted intratumoral IFN-I and immune compositional differences between responder and non-responder individuals can be transferred by fecal microbiota transplantation. Our study uncovers a mechanistic link between the microbiota and the innate TME that can be harnessed to improve cancer therapies.
Topics: Akkermansia; Animals; Dendritic Cells; Dietary Fiber; Dinucleoside Phosphates; Humans; Immune Checkpoint Inhibitors; Immunomodulation; Interferon Type I; Killer Cells, Natural; Macrophages; Melanoma; Membrane Proteins; Mice, Inbred BALB C; Mice, Inbred C57BL; Microbiota; Monocytes; Phagocytes; Transcription, Genetic; Tumor Microenvironment; Mice
PubMed: 34624222
DOI: 10.1016/j.cell.2021.09.019 -
Nature Dec 2022Cyclic dinucleotides (CDNs) are ubiquitous signalling molecules in all domains of life. Mammalian cells produce one CDN, 2'3'-cGAMP, through cyclic GMP-AMP synthase...
Cyclic dinucleotides (CDNs) are ubiquitous signalling molecules in all domains of life. Mammalian cells produce one CDN, 2'3'-cGAMP, through cyclic GMP-AMP synthase after detecting cytosolic DNA signals. 2'3'-cGAMP, as well as bacterial and synthetic CDN analogues, can act as second messengers to activate stimulator of interferon genes (STING) and elicit broad downstream responses. Extracellular CDNs must traverse the cell membrane to activate STING, a process that is dependent on the solute carrier SLC19A1. Moreover, SLC19A1 represents the major transporter for folate nutrients and antifolate therapeutics, thereby placing SLC19A1 as a key factor in multiple physiological and pathological processes. How SLC19A1 recognizes and transports CDNs, folate and antifolate is unclear. Here we report cryo-electron microscopy structures of human SLC19A1 (hSLC19A1) in a substrate-free state and in complexes with multiple CDNs from different sources, a predominant natural folate and a new-generation antifolate drug. The structural and mutagenesis results demonstrate that hSLC19A1 uses unique yet divergent mechanisms to recognize CDN- and folate-type substrates. Two CDN molecules bind within the hSLC19A1 cavity as a compact dual-molecule unit, whereas folate and antifolate bind as a monomer and occupy a distinct pocket of the cavity. Moreover, the structures enable accurate mapping and potential mechanistic interpretation of hSLC19A1 with loss-of-activity and disease-related mutations. Our research provides a framework for understanding the mechanism of SLC19-family transporters and is a foundation for the development of potential therapeutics.
Topics: Animals; Humans; Cryoelectron Microscopy; Dinucleoside Phosphates; Folic Acid; Folic Acid Antagonists; Mammals; Nucleotides, Cyclic; Reduced Folate Carrier Protein
PubMed: 36265513
DOI: 10.1038/s41586-022-05452-z -
Nature Apr 2022Stimulator of interferon genes (STING) is an adaptor protein in innate immunity against DNA viruses or bacteria. STING-mediated immunity could be exploited in the...
Stimulator of interferon genes (STING) is an adaptor protein in innate immunity against DNA viruses or bacteria. STING-mediated immunity could be exploited in the development of vaccines or cancer immunotherapies. STING is a transmembrane dimeric protein that is located in the endoplasmic reticulum or in the Golgi apparatus. STING is activated by the binding of its cytoplasmic ligand-binding domain to cyclic dinucleotides that are produced by the DNA sensor cyclic GMP-AMP (cGAMP) synthase or by invading bacteria. Cyclic dinucleotides induce a conformational change in the STING ligand-binding domain, which leads to a high-order oligomerization of STING that is essential for triggering the downstream signalling pathways. However, the cGAMP-induced STING oligomers tend to dissociate in solution and have not been resolved to high resolution, which limits our understanding of the activation mechanism. Here we show that a small-molecule agonist, compound 53 (C53), promotes the oligomerization and activation of human STING through a mechanism orthogonal to that of cGAMP. We determined a cryo-electron microscopy structure of STING bound to both C53 and cGAMP, revealing a stable oligomer that is formed by side-by-side packing and has a curled overall shape. Notably, C53 binds to a cryptic pocket in the STING transmembrane domain, between the two subunits of the STING dimer. This binding triggers outward shifts of transmembrane helices in the dimer, and induces inter-dimer interactions between these helices to mediate the formation of the high-order oligomer. Our functional analyses show that cGAMP and C53 together induce stronger activation of STING than either ligand alone.
Topics: Cell Cycle Proteins; Cryoelectron Microscopy; Dinucleoside Phosphates; Humans; Immunity, Innate; Ligands; Membrane Proteins; Nucleotides, Cyclic; Tumor Suppressor Proteins
PubMed: 35388221
DOI: 10.1038/s41586-022-04559-7 -
Nature Communications Feb 2022In addition to its role as a TB vaccine, BCG has been shown to elicit heterologous protection against many other pathogens including viruses through a process termed...
In addition to its role as a TB vaccine, BCG has been shown to elicit heterologous protection against many other pathogens including viruses through a process termed trained immunity. Despite its potential as a broadly protective vaccine, little has been done to determine if BCG-mediated trained immunity levels can be optimized. Here we re-engineer BCG to express high levels of c-di-AMP, a PAMP recognized by stimulator of interferon genes (STING). We find that BCG overexpressing c-di-AMP elicits more potent signatures of trained immunity including higher pro-inflammatory cytokine responses, greater myeloid cell reprogramming toward inflammatory and activated states, and enhances epigenetic and metabolomic changes. In a model of bladder cancer, we also show that re-engineered BCG induces trained immunity and improved functionality. These results indicate that trained immunity levels and antitumor efficacy may be increased by modifying BCG to express higher levels of key PAMP molecules.
Topics: Animals; BCG Vaccine; CD8-Positive T-Lymphocytes; Cancer Vaccines; Cell Line, Tumor; Cytokines; Dinucleoside Phosphates; Humans; Immunity, Innate; Macrophages; Membrane Proteins; Mice; Myeloid Cells; Pathogen-Associated Molecular Pattern Molecules; Rats; Urinary Bladder Neoplasms; Urothelium; Vaccination
PubMed: 35169141
DOI: 10.1038/s41467-022-28509-z -
Nature Immunology Feb 2022The volume-regulated anion channel (VRAC) is formed by LRRC8 proteins and is responsible for the regulatory volume decrease (RVD) after hypotonic cell swelling. Besides...
The volume-regulated anion channel (VRAC) is formed by LRRC8 proteins and is responsible for the regulatory volume decrease (RVD) after hypotonic cell swelling. Besides chloride, VRAC transports other molecules, for example, immunomodulatory cyclic dinucleotides (CDNs) including 2'3'cGAMP. Here, we identify LRRC8C as a critical component of VRAC in T cells, where its deletion abolishes VRAC currents and RVD. T cells of Lrrc8c mice have increased cell cycle progression, proliferation, survival, Ca influx and cytokine production-a phenotype associated with downmodulation of p53 signaling. Mechanistically, LRRC8C mediates the transport of 2'3'cGAMP in T cells, resulting in STING and p53 activation. Inhibition of STING recapitulates the phenotype of LRRC8C-deficient T cells, whereas overexpression of p53 inhibits their enhanced T cell function. Lrrc8c mice have exacerbated T cell-dependent immune responses, including immunity to influenza A virus infection and experimental autoimmune encephalomyelitis. Our results identify cGAMP uptake through LRRC8C and STING-p53 signaling as a new inhibitory signaling pathway in T cells and adaptive immunity.
Topics: Animals; Anions; Calcium; Dinucleoside Phosphates; Female; Ion Channels; Membrane Proteins; Mice; Mice, Inbred C57BL; Nucleotides, Cyclic; Signal Transduction; T-Lymphocytes; Tumor Suppressor Protein p53
PubMed: 35105987
DOI: 10.1038/s41590-021-01105-x -
Molecules (Basel, Switzerland) Nov 2019Dinucleoside 5',5'-polyphosphates (DNPs) are endogenous substances that play important intra- and extracellular roles in various biological processes, such as cell... (Review)
Review
Dinucleoside 5',5'-polyphosphates (DNPs) are endogenous substances that play important intra- and extracellular roles in various biological processes, such as cell proliferation, regulation of enzymes, neurotransmission, platelet disaggregation and modulation of vascular tone. Various methodologies have been developed over the past fifty years to access these compounds, involving enzymatic processes or chemical procedures based either on P(III) or P(V) chemistry. Both solution-phase and solid-support strategies have been developed and are reported here. Recently, green chemistry approaches have emerged, offering attracting alternatives. This review outlines the main synthetic pathways for the preparation of dinucleoside 5',5'-polyphosphates, focusing on pharmacologically relevant compounds, and highlighting recent advances.
Topics: Deoxycytosine Nucleotides; Dinucleoside Phosphates; Dry Eye Syndromes; Green Chemistry Technology; Humans; Ophthalmic Solutions; Phosphorylation; Polyphosphates; Purinergic P2Y Receptor Agonists; Receptors, Purinergic; Uracil Nucleotides; Uridine
PubMed: 31783537
DOI: 10.3390/molecules24234334 -
Microbiology (Reading, England) Nov 2019Antibiotic producing sense and respond to environmental signals by using nucleotide second messengers, including (p)ppGpp, cAMP, c-di-GMP and c-di-AMP. As summarized in... (Review)
Review
Antibiotic producing sense and respond to environmental signals by using nucleotide second messengers, including (p)ppGpp, cAMP, c-di-GMP and c-di-AMP. As summarized in this review, these molecules are important message carriers that coordinate the complex morphological transition from filamentous growth to sporulation along with the secondary metabolite production. Here, we provide an overview of the enzymes that make and break these second messengers and suggest candidates for (p)ppGpp and cAMP enzymes to be studied. We highlight the target molecules that bind these signalling molecules and elaborate individual functions that they control in the context of development. Finally, we discuss open questions in the field, which may guide future studies in this exciting research area.
Topics: Bacterial Proteins; Cyclic AMP; Dinucleoside Phosphates; Gene Expression Regulation, Bacterial; Guanine Nucleotides; Protein Binding; Second Messenger Systems; Spores, Bacterial; Streptomyces
PubMed: 31535967
DOI: 10.1099/mic.0.000846 -
Molecular Microbiology Dec 2023Cyclic dimeric adenosine monophosphate (c-di-AMP) has been well studied in bacteria, including those of the genus Streptococcus, since the first recognition of this... (Review)
Review
Cyclic dimeric adenosine monophosphate (c-di-AMP) has been well studied in bacteria, including those of the genus Streptococcus, since the first recognition of this dinucleotide in 2008. Streptococci possess a sole diadenylate cyclase, CdaA, and distinct c-di-AMP phosphodiesterases. Interestingly, cdaA is required for viability of some streptococcal species but not all when streptococci are grown in standard laboratory media. Bacteria of this genus also have distinct c-di-AMP effector proteins, diverse c-di-AMP-signaling pathways, and subsequent biological outcomes. In streptococci, c-di-AMP may influence bacterial growth, morphology, biofilm formation, competence program, drug resistance, and bacterial pathogenesis. c-di-AMP secreted by streptococci has also been shown to interact with the mammalian host and induces immune responses including type I interferon production. In this review, we summarize the reported c-di-AMP networks in seven species of the genus Streptococcus, which cause diverse clinical manifestations, and propose future perspectives to investigate the signaling molecule in these streptococcal pathogens.
Topics: Animals; Bacterial Proteins; Second Messenger Systems; Dinucleoside Phosphates; Cyclic AMP; Bacteria; Streptococcus; Mammals
PubMed: 37898560
DOI: 10.1111/mmi.15187 -
FEMS Microbiology Reviews Nov 2020Cyclic dimeric adenosine 3',5'-monophosphate (c-di-AMP) is an emerging second messenger in bacteria and archaea that is synthesized from two molecules of ATP by... (Review)
Review
Cyclic dimeric adenosine 3',5'-monophosphate (c-di-AMP) is an emerging second messenger in bacteria and archaea that is synthesized from two molecules of ATP by diadenylate cyclases and degraded to pApA or two AMP molecules by c-di-AMP-specific phosphodiesterases. Through binding to specific protein- and riboswitch-type receptors, c-di-AMP regulates a wide variety of prokaryotic physiological functions, including maintaining the osmotic pressure, balancing central metabolism, monitoring DNA damage and controlling biofilm formation and sporulation. It mediates bacterial adaptation to a variety of environmental parameters and can also induce an immune response in host animal cells. In this review, we discuss the phylogenetic distribution of c-di-AMP-related enzymes and receptors and provide some insights into the various aspects of c-di-AMP signaling pathways based on more than a decade of research. We emphasize the key role of c-di-AMP in maintaining bacterial osmotic balance, especially in Gram-positive bacteria. In addition, we discuss the future direction and trends of c-di-AMP regulatory network, such as the likely existence of potential c-di-AMP transporter(s), the possibility of crosstalk between c-di-AMP signaling with other regulatory systems, and the effects of c-di-AMP compartmentalization. This review aims to cover the broad spectrum of research on the regulatory functions of c-di-AMP and c-di-AMP signaling pathways.
Topics: Bacteria; Bacterial Physiological Phenomena; Dinucleoside Phosphates; Phylogeny; Research; Signal Transduction
PubMed: 32472931
DOI: 10.1093/femsre/fuaa019 -
Current Opinion in Microbiology Apr 2021Cyclic dinucleotide (cdN) second messengers are essential for bacteria to sense and adapt to their environment. These signals were first discovered with the... (Review)
Review
Cyclic dinucleotide (cdN) second messengers are essential for bacteria to sense and adapt to their environment. These signals were first discovered with the identification of 3'-5', 3'-5' cyclic di-GMP (c-di-GMP) in 1987, a second messenger that is now known to be the linchpin signaling pathway modulating bacterial motility and biofilm formation. In the past 15 years, three more cdNs were uncovered: 3'-5', 3'-5' cyclic di-AMP (c-di-AMP) and 3'-5', 3'-5' cyclic GMP-AMP (3',3' cGAMP) in bacteria and 2'-5', 3'-5' cyclic GMP-AMP (2',3' cGAMP) in eukaryotes. We now appreciate that bacteria can synthesize many varieties of cdNs from every ribonucleotide, and even cyclic trinucleotide (ctN) second messengers have been discovered. Here we highlight our current understanding of c-di-GMP and c-di-AMP in bacterial physiology and focus on recent advances in 3',3' cGAMP signaling effectors, its role in bacterial phage response, and the diversity of its synthase family.
Topics: Bacteria; Bacterial Physiological Phenomena; Bacterial Proteins; Cyclic GMP; Dinucleoside Phosphates; Nucleotides, Cyclic; Oligonucleotides; Second Messenger Systems
PubMed: 33640793
DOI: 10.1016/j.mib.2021.01.017