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1.
Nat Commun ; 12(1): 61, 2021 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-33397928

RESUMO

Coat protein complex I (COP-I) mediates the retrograde transport from the Golgi apparatus to the endoplasmic reticulum (ER). Mutation of the COPA gene, encoding one of the COP-I subunits (α-COP), causes an immune dysregulatory disease known as COPA syndrome. The molecular mechanism by which the impaired retrograde transport results in autoinflammation remains poorly understood. Here we report that STING, an innate immunity protein, is a cargo of the retrograde membrane transport. In the presence of the disease-causative α-COP variants, STING cannot be retrieved back to the ER from the Golgi. The forced Golgi residency of STING results in the cGAS-independent and palmitoylation-dependent activation of the STING downstream signaling pathway. Surf4, a protein that circulates between the ER/ ER-Golgi intermediate compartment/ Golgi, binds STING and α-COP, and mediates the retrograde transport of STING to the ER. The STING/Surf4/α-COP complex is disrupted in the presence of the disease-causative α-COP variant. We also find that the STING ligand cGAMP impairs the formation of the STING/Surf4/α-COP complex. Our results suggest a homeostatic regulation of STING at the resting state by retrograde membrane traffic and provide insights into the pathogenesis of COPA syndrome.


Assuntos
Retículo Endoplasmático/metabolismo , Homeostase , Proteínas de Membrana/metabolismo , Animais , Brefeldina A/farmacologia , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/efeitos dos fármacos , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/ultraestrutura , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/ultraestrutura , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Complexo de Golgi/efeitos dos fármacos , Complexo de Golgi/metabolismo , Complexo de Golgi/ultraestrutura , Células HEK293 , Humanos , Lipoilação , Luciferases/metabolismo , Camundongos , Nucleotidiltransferases/metabolismo , Ligação Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos
2.
Nat Commun ; 11(1): 4979, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-33020468

RESUMO

Cellular senescence is a known driver of carcinogenesis and age-related diseases, yet senescence is required for various physiological processes. However, the mechanisms and factors that control the negative effects of senescence while retaining its benefits are still elusive. Here, we show that the rasGAP SH3-binding protein 1 (G3BP1) is required for the activation of the senescent-associated secretory phenotype (SASP). During senescence, G3BP1 achieves this effect by promoting the association of the cyclic GMP-AMP synthase (cGAS) with cytosolic chromatin fragments. In turn, G3BP1, through cGAS, activates the NF-κB and STAT3 pathways, promoting SASP expression and secretion. G3BP1 depletion or pharmacological inhibition impairs the cGAS-pathway preventing the expression of SASP factors without affecting cell commitment to senescence. These SASPless senescent cells impair senescence-mediated growth of cancer cells in vitro and tumor growth in vivo. Our data reveal that G3BP1 is required for SASP expression and that SASP secretion is a primary mediator of senescence-associated tumor growth.


Assuntos
Senescência Celular/fisiologia , DNA Helicases/metabolismo , Neoplasias/patologia , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , RNA Helicases/metabolismo , Proteínas com Motivo de Reconhecimento de RNA/metabolismo , Células A549 , Animais , Carcinogênese , Linhagem Celular , Movimento Celular , Citocinas/metabolismo , DNA Helicases/antagonistas & inibidores , DNA Helicases/deficiência , Humanos , Inflamação , Camundongos , Neoplasias/metabolismo , Nucleotidiltransferases/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/antagonistas & inibidores , Proteínas de Ligação a Poli-ADP-Ribose/deficiência , RNA Helicases/antagonistas & inibidores , RNA Helicases/deficiência , Proteínas com Motivo de Reconhecimento de RNA/antagonistas & inibidores , Proteínas com Motivo de Reconhecimento de RNA/deficiência , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Fator de Transcrição RelA/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(41): 25494-25504, 2020 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-32999062

RESUMO

During DNA replication, replicative DNA polymerases may encounter DNA lesions, which can stall replication forks. One way to prevent replication fork stalling is through the recruitment of specialized translesion synthesis (TLS) polymerases that have evolved to incorporate nucleotides opposite DNA lesions. Rev1 is a specialized TLS polymerase that bypasses abasic sites, as well as minor-groove and exocyclic guanine adducts. Lesion bypass is accomplished using a unique protein-template mechanism in which the templating base is evicted from the DNA helix and the incoming dCTP hydrogen bonds with an arginine side chain of Rev1. To understand the protein-template mechanism at an atomic level, we employed a combination of time-lapse X-ray crystallography, molecular dynamics simulations, and DNA enzymology on the Saccharomyces cerevisiae Rev1 protein. We find that Rev1 evicts the templating base from the DNA helix prior to binding the incoming nucleotide. Binding the incoming nucleotide changes the conformation of the DNA substrate to orient it for nucleotidyl transfer, although this is not coupled to large structural changes in Rev1 like those observed with other DNA polymerases. Moreover, we found that following nucleotide incorporation, Rev1 converts the pyrophosphate product to two monophosphates, which drives the reaction in the forward direction and prevents pyrophosphorolysis. Following nucleotide incorporation, the hydrogen bonds between the incorporated nucleotide and the arginine side chain are broken, but the templating base remains extrahelical. These postcatalytic changes prevent potentially mutagenic processive synthesis by Rev1 and facilitate dissociation of the DNA product from the enzyme.


Assuntos
Reparo do DNA , Replicação do DNA/fisiologia , DNA/metabolismo , Nucleotidiltransferases/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , DNA/química , Dano ao DNA , DNA Polimerase Dirigida por DNA/genética , DNA Polimerase Dirigida por DNA/metabolismo , Regulação Fúngica da Expressão Gênica , Simulação de Dinâmica Molecular , Nucleotidiltransferases/genética , Proteínas de Saccharomyces cerevisiae/genética
4.
Nature ; 586(7829): 429-433, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32877915

RESUMO

Stimulator of interferon genes (STING) is a receptor in human cells that senses foreign cyclic dinucleotides that are released during bacterial infection and in endogenous cyclic GMP-AMP signalling during viral infection and anti-tumour immunity1-5. STING shares no structural homology with other known signalling proteins6-9, which has limited attempts at functional analysis and prevented explanation of the origin of cyclic dinucleotide signalling in mammalian innate immunity. Here we reveal functional STING homologues encoded within prokaryotic defence islands, as well as a conserved mechanism of signal activation. Crystal structures of bacterial STING define a minimal homodimeric scaffold that selectively responds to cyclic di-GMP synthesized by a neighbouring cGAS/DncV-like nucleotidyltransferase (CD-NTase) enzyme. Bacterial STING domains couple the recognition of cyclic dinucleotides with the formation of protein filaments to drive oligomerization of TIR effector domains and rapid NAD+ cleavage. We reconstruct the evolutionary events that followed the acquisition of STING into metazoan innate immunity, and determine the structure of a full-length TIR-STING fusion from the Pacific oyster Crassostrea gigas. Comparative structural analysis demonstrates how metazoan-specific additions to the core STING scaffold enabled a switch from direct effector function to regulation of antiviral transcription. Together, our results explain the mechanism of STING-dependent signalling and reveal the conservation of a functional cGAS-STING pathway in prokaryotic defence against bacteriophages.


Assuntos
Bactérias/metabolismo , Proteínas de Bactérias/metabolismo , GMP Cíclico/análogos & derivados , Evolução Molecular , Proteínas de Membrana , Sistemas do Segundo Mensageiro , Animais , Bactérias/química , Bactérias/virologia , Proteínas de Bactérias/química , Bacteriófagos , Cristalografia por Raios X , GMP Cíclico/metabolismo , Proteínas de Membrana/química , Modelos Moleculares , NAD/metabolismo , Nucleotidiltransferases/metabolismo
5.
Trends Parasitol ; 36(9): 773-784, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32736985

RESUMO

Emerging evidence suggests that the DNA-sensing pathway plays a crucial role in innate immunity against multiple diseases, especially infectious diseases. Cyclic GMP-AMP synthase (cGAS), as a DNA sensor, and stimulator of interferon (IFN) genes (STING), as an adaptor protein, are the central components that link DNA sensing to immunologic functions - including, but not limited to, the type I IFN response. Recently, a series of studies have revealed that genomic DNA from protozoan parasites triggers the cGAS-STING pathway, and these studies identified the positive and negative regulators that modulate the signaling in parasite infection. Here, we summarize current understanding of the critical functions and potential applications of the cGAS-STING axis in parasitic diseases, specifically those caused by malaria parasites.


Assuntos
Interações Hospedeiro-Parasita/imunologia , Malária/imunologia , Malária/parasitologia , Proteínas de Membrana/metabolismo , Nucleotidiltransferases/metabolismo , Plasmodium/genética , Plasmodium/imunologia , Animais , DNA de Protozoário/genética , DNA de Protozoário/imunologia , Humanos , Transdução de Sinais/genética
6.
Science ; 369(6505): 823-828, 2020 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-32792394

RESUMO

The appearance of DNA in the cytosol is perceived as a danger signal that stimulates potent immune responses through cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS). How cells regulate the activity of cGAS toward self-DNA and guard against potentially damaging autoinflammatory responses is a fundamental biological question. Here, we identify barrier-to-autointegration factor 1 (BAF) as a natural opponent of cGAS activity on genomic self-DNA. We show that BAF dynamically outcompetes cGAS for DNA binding, hence prohibiting the formation of DNA-cGAS complexes that are essential for enzymatic activity. Upon acute loss of nuclear membrane integrity, BAF is necessary to restrict cGAS activity on exposed DNA. Our observations reveal a safeguard mechanism, distinct from physical separation, by which cells protect themselves against aberrant immune responses toward genomic DNA.


Assuntos
Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/metabolismo , DNA/imunologia , Imunidade Inata , Nucleotidiltransferases/metabolismo , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Técnicas de Silenciamento de Genes , Células HeLa , Humanos , Membrana Nuclear/metabolismo
7.
Nat Commun ; 11(1): 3907, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764578

RESUMO

Nucleic acids can fold into G-quadruplex (G4) structures that can fine-tune biological processes. Proteins are required to recognize G4 structures and coordinate their function. Here we identify Zuo1 as a novel G4-binding protein in vitro and in vivo. In vivo in the absence of Zuo1 fewer G4 structures form, cell growth slows and cells become UV sensitive. Subsequent experiments reveal that these cellular changes are due to reduced levels of G4 structures. Zuo1 function at G4 structures results in the recruitment of nucleotide excision repair (NER) factors, which has a positive effect on genome stability. Cells lacking functional NER, as well as Zuo1, accumulate G4 structures, which become accessible to translesion synthesis. Our results suggest a model in which Zuo1 supports NER function and regulates the choice of the DNA repair pathway nearby G4 structures.


Assuntos
Reparo do DNA/fisiologia , Quadruplex G , Chaperonas Moleculares/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Sítios de Ligação/genética , Dano ao DNA , Reparo do DNA/genética , DNA Fúngico/química , DNA Fúngico/genética , DNA Fúngico/metabolismo , Deleção de Genes , Aptidão Genética , Genoma Fúngico , Instabilidade Genômica , Modelos Biológicos , Chaperonas Moleculares/genética , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética
8.
Proc Natl Acad Sci U S A ; 117(35): 21568-21575, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817552

RESUMO

The DNA sensor cGMP-AMP synthase (cGAS) senses cytosolic microbial or self DNA to initiate a MITA/STING-dependent innate immune response. cGAS is regulated by various posttranslational modifications at its C-terminal catalytic domain. Whether and how its N-terminal unstructured domain is regulated by posttranslational modifications remain unknown. We identified the acetyltransferase KAT5 as a positive regulator of cGAS-mediated innate immune signaling. Overexpression of KAT5 potentiated viral-DNA-triggered transcription of downstream antiviral genes, whereas a KAT5 deficiency had the opposite effects. Mice with inactivated Kat5 exhibited lower levels of serum cytokines in response to DNA virus infection, higher viral titers in the brains, and more susceptibility to DNA-virus-induced death. Mechanistically, KAT5 catalyzed acetylation of cGAS at multiple lysine residues in its N-terminal domain, which promoted its DNA-binding ability. Our findings suggest that KAT5-mediated cGAS acetylation at its N terminus is important for efficient innate immune response to DNA virus.


Assuntos
Infecções por Vírus de DNA/imunologia , Vírus de DNA/imunologia , Lisina Acetiltransferase 5/imunologia , Nucleotidiltransferases/imunologia , Acetilação , Animais , GMP Cíclico/metabolismo , Infecções por Vírus de DNA/genética , Infecções por Vírus de DNA/metabolismo , Vírus de DNA/genética , Feminino , Células HEK293 , Células HeLa , Interações Hospedeiro-Patógeno , Humanos , Imunidade Inata , Interferon beta/imunologia , Lisina Acetiltransferase 5/genética , Lisina Acetiltransferase 5/metabolismo , Masculino , Camundongos , Camundongos Knockout , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Processamento de Proteína Pós-Traducional , Transdução de Sinais , Proteínas Virais/metabolismo
9.
PLoS Comput Biol ; 16(8): e1007898, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797038

RESUMO

New treatments for diseases caused by antimicrobial-resistant microorganisms can be developed by identifying unexplored therapeutic targets and by designing efficient drug screening protocols. In this study, we have screened a library of compounds to find ligands for the flavin-adenine dinucleotide synthase (FADS) -a potential target for drug design against tuberculosis and pneumonia- by implementing a new and efficient virtual screening protocol. The protocol has been developed for the in silico search of ligands of unexplored therapeutic targets, for which limited information about ligands or ligand-receptor structures is available. It implements an integrative funnel-like strategy with filtering layers that increase in computational accuracy. The protocol starts with a pharmacophore-based virtual screening strategy that uses ligand-free receptor conformations from molecular dynamics (MD) simulations. Then, it performs a molecular docking stage using several docking programs and an exponential consensus ranking strategy. The last filter, samples the conformations of compounds bound to the target using MD simulations. The MD conformations are scored using several traditional scoring functions in combination with a newly-proposed score that takes into account the fluctuations of the molecule with a Morse-based potential. The protocol was optimized and validated using a compound library with known ligands of the Corynebacterium ammoniagenes FADS. Then, it was used to find new FADS ligands from a compound library of 14,000 molecules. A small set of 17 in silico filtered molecules were tested experimentally. We identified five inhibitors of the activity of the flavin adenylyl transferase module of the FADS, and some of them were able to inhibit growth of three bacterial species: C. ammoniagenes, Mycobacterium tuberculosis, and Streptococcus pneumoniae, where the last two are human pathogens. Overall, the results show that the integrative VS protocol is a cost-effective solution for the discovery of ligands of unexplored therapeutic targets.


Assuntos
Antibacterianos , Proteínas de Bactérias , Nucleotidiltransferases , Antibacterianos/química , Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Corynebacterium/efeitos dos fármacos , Corynebacterium/enzimologia , Desenho de Fármacos , Farmacorresistência Bacteriana/efeitos dos fármacos , Ligantes , Simulação de Dinâmica Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologia , Nucleotidiltransferases/antagonistas & inibidores , Nucleotidiltransferases/química , Nucleotidiltransferases/metabolismo
10.
Proc Natl Acad Sci U S A ; 117(32): 19475-19486, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32709741

RESUMO

The DNA sensor cGAS catalyzes the production of the cyclic dinucleotide cGAMP, resulting in type I interferon responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T cells. Activated primary CD4+ T cells expressed cGAS and responded to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4+ T cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1ΔUL41N) resulted in a cGAS-dependent type I interferon response. In accordance with our results in primary CD4+ T cells, plasmid challenge or HSV-1ΔUL41N inoculation of T cell lines provoked an entirely cGAS-dependent type I interferon response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent interferon response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1ΔUL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS.


Assuntos
Linfócitos T CD4-Positivos/virologia , HIV-1/fisiologia , Interferon Tipo I/metabolismo , Nucleotidiltransferases/metabolismo , Animais , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Células Cultivadas , DNA Viral/fisiologia , Exodesoxirribonucleases/genética , Exodesoxirribonucleases/metabolismo , Herpesvirus Humano 1/fisiologia , Interações Hospedeiro-Patógeno , Humanos , Imunidade Inata , Fator Regulador 3 de Interferon/metabolismo , Camundongos , Nucleotidiltransferases/genética , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Fosforilação , Especificidade da Espécie , Replicação Viral
11.
Nature ; 582(7811): 283-288, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32499657

RESUMO

Mobile genetic elements threaten genome integrity in all organisms. RDE-3 (also known as MUT-2) is a ribonucleotidyltransferase that is required for transposon silencing and RNA interference in Caenorhabditis elegans1-4. When tethered to RNAs in heterologous expression systems, RDE-3 can add long stretches of alternating non-templated uridine (U) and guanosine (G) ribonucleotides to the 3' termini of these RNAs (designated poly(UG) or pUG tails)5. Here we show that, in its natural context in C. elegans, RDE-3 adds pUG tails to targets of RNA interference, as well as to transposon RNAs. RNA fragments attached to pUG tails with more than 16 perfectly alternating 3' U and G nucleotides become gene-silencing agents. pUG tails promote gene silencing by recruiting RNA-dependent RNA polymerases, which use pUG-tailed RNAs (pUG RNAs) as templates to synthesize small interfering RNAs (siRNAs). Our results show that cycles of pUG RNA-templated siRNA synthesis and siRNA-directed pUG RNA biogenesis underlie double-stranded-RNA-directed transgenerational epigenetic inheritance in the C. elegans germline. We speculate that this pUG RNA-siRNA silencing loop enables parents to inoculate progeny against the expression of unwanted or parasitic genetic elements.


Assuntos
Caenorhabditis elegans/genética , Caenorhabditis elegans/parasitologia , Epigênese Genética/genética , Genoma/genética , Hereditariedade , Poli G/genética , Poli U/genética , RNA Mensageiro/genética , Animais , Caenorhabditis elegans/citologia , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Células Germinativas/citologia , Células Germinativas/metabolismo , Masculino , Nucleotidiltransferases/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , Moldes Genéticos
12.
Nat Rev Mol Cell Biol ; 21(9): 542-556, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32483315

RESUMO

RNA tailing, or the addition of non-templated nucleotides to the 3' end of RNA, is the most frequent and conserved type of RNA modification. The addition of tails and their composition reflect RNA maturation stages and have important roles in determining the fate of the modified RNAs. Apart from canonical poly(A) polymerases, which add poly(A) tails to mRNAs in a transcription-coupled manner, a family of terminal nucleotidyltransferases (TENTs), including terminal uridylyltransferases (TUTs), modify RNAs post-transcriptionally to control RNA stability and activity. The human genome encodes 11 different TENTs with distinct substrate specificity, intracellular localization and tissue distribution. In this Review, we discuss recent advances in our understanding of non-canonical RNA tails, with a focus on the functions of human TENTs, which include uridylation, mixed tailing and post-transcriptional polyadenylation of mRNAs, microRNAs and other types of non-coding RNA.


Assuntos
Regulação da Expressão Gênica/fisiologia , Processamento Pós-Transcricional do RNA/fisiologia , RNA/genética , Regiões 3' não Traduzidas/genética , Regiões 3' não Traduzidas/fisiologia , Animais , Regulação da Expressão Gênica/genética , Humanos , MicroRNAs/genética , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Poliadenilação , RNA/metabolismo , Processamento Pós-Transcricional do RNA/genética , Estabilidade de RNA/genética , RNA Mensageiro/genética
13.
Proc Natl Acad Sci U S A ; 117(27): 15923-15934, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571920

RESUMO

Burkholderia pseudomallei is the causative agent of melioidosis, an infectious disease in the tropics and subtropics with high morbidity and mortality. The facultative intracellular bacterium induces host cell fusion through its type VI secretion system 5 (T6SS5) as an important part of its pathogenesis in mammalian hosts. This allows it to spread intercellularly without encountering extracellular host defenses. We report that bacterial T6SS5-dependent cell fusion triggers type I IFN gene expression in the host and leads to activation of the cGAMP synthase-stimulator of IFN genes (cGAS-STING) pathway, independent of bacterial ligands. Aberrant and abortive mitotic events result in the formation of micronuclei colocalizing with cGAS, which is activated by double-stranded DNA. Surprisingly, cGAS-STING activation leads to type I IFN transcription but not its production. Instead, the activation of cGAS and STING results in autophagic cell death. We also observed type I IFN gene expression, micronuclei formation, and death of chemically induced cell fusions. Therefore, we propose that the cGAS-STING pathway senses unnatural cell fusion through micronuclei formation as a danger signal, and consequently limits aberrant cell division and potential cellular transformation through autophagic death induction.


Assuntos
Proteínas de Membrana/metabolismo , Nucleotidiltransferases/genética , Burkholderia pseudomallei/metabolismo , Fusão Celular , Dano ao DNA , Regulação da Expressão Gênica , Instabilidade Genômica , Células Hep G2 , Humanos , Imunidade Inata , Interferon Tipo I/genética , Interferon Tipo I/metabolismo , Proteínas de Membrana/genética , Microscopia Confocal , Nucleotidiltransferases/metabolismo , Transdução de Sinais
14.
Proc Natl Acad Sci U S A ; 117(27): 15989-15999, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32581130

RESUMO

Huntington disease (HD) is caused by an expansion mutation of the N-terminal polyglutamine of huntingtin (mHTT). mHTT is ubiquitously present, but it induces noticeable damage to the brain's striatum, thereby affecting motor, psychiatric, and cognitive functions. The striatal damage and progression of HD are associated with the inflammatory response; however, the underlying molecular mechanisms remain unclear. Here, we report that cGMP-AMP synthase (cGAS), a DNA sensor, is a critical regulator of inflammatory and autophagy responses in HD. Ribosome profiling revealed that the cGAS mRNA has high ribosome occupancy at exon 1 and codon-specific pauses at positions 171 (CCG) and 172 (CGT) in HD striatal cells. Moreover, the protein levels and activity of cGAS (based on the phosphorylated STING and phosphorylated TBK1 levels), and the expression and ribosome occupancy of cGAS-dependent inflammatory genes (Ccl5 and Cxcl10) are increased in HD striatum. Depletion of cGAS diminishes cGAS activity and decreases the expression of inflammatory genes while suppressing the up-regulation of autophagy in HD cells. In contrast, reinstating cGAS in cGAS-depleted HD cells activates cGAS activity and promotes inflammatory and autophagy responses. Ribosome profiling also revealed that LC3A and LC3B, the two major autophagy initiators, show altered ribosome occupancy in HD cells. We also detected the presence of numerous micronuclei, which are known to induce cGAS, in the cytoplasm of neurons derived from human HD embryonic stem cells. Collectively, our results indicate that cGAS is up-regulated in HD and mediates inflammatory and autophagy responses. Thus, targeting the cGAS pathway may offer therapeutic benefits in HD.


Assuntos
Autofagia/fisiologia , Doença de Huntington/genética , Doença de Huntington/metabolismo , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Animais , Quimiocina CCL5/metabolismo , Quimiocina CXCL10/metabolismo , Corpo Estriado/metabolismo , Células-Tronco Embrionárias , Humanos , Proteína Huntingtina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Neostriado/metabolismo , Neurônios/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/metabolismo , Transcriptoma , Regulação para Cima
15.
Nat Immunol ; 21(7): 727-735, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32541831

RESUMO

Stimulator-of-interferon genes (STING) is vital for sensing cytosolic DNA and initiating innate immune responses against microbial infection and tumors. Redox homeostasis is the balance of oxidative and reducing reactions present in all living systems. Yet, how the intracellular redox state controls STING activation is unclear. Here, we show that cellular redox homeostasis maintained by glutathione peroxidase 4 (GPX4) is required for STING activation. GPX4 deficiency enhanced cellular lipid peroxidation and thus specifically inhibited the cGAS-STING pathway. Concordantly, GPX4 deficiency inhibited herpes simplex virus-1 (HSV-1)-induced innate antiviral immune responses and promoted HSV-1 replication in vivo. Mechanistically, GPX4 inactivation increased production of lipid peroxidation, which led to STING carbonylation at C88 and inhibited its trafficking from the endoplasmic reticulum (ER) to the Golgi complex. Thus, cellular stress-induced lipid peroxidation specifically attenuates the STING DNA-sensing pathway, suggesting that GPX4 facilitates STING activation by maintaining redox homeostasis of lipids.


Assuntos
Herpes Simples/imunologia , Proteínas de Membrana/metabolismo , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/metabolismo , Animais , Carbolinas/farmacologia , Células Cultivadas , DNA Viral/imunologia , Modelos Animais de Doenças , Retículo Endoplasmático/metabolismo , Feminino , Fibroblastos , Complexo de Golgi/metabolismo , Células HEK293 , Herpes Simples/virologia , Herpesvirus Humano 1/genética , Herpesvirus Humano 1/imunologia , Homeostase/imunologia , Humanos , Imunidade Inata , Peroxidação de Lipídeos/genética , Peroxidação de Lipídeos/imunologia , Macrófagos Peritoneais/citologia , Macrófagos Peritoneais/imunologia , Macrófagos Peritoneais/metabolismo , Proteínas de Membrana/imunologia , Camundongos , Camundongos Knockout , Nucleotidiltransferases/metabolismo , Oxirredução , Oximas/farmacologia , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/antagonistas & inibidores , Fosfolipídeo Hidroperóxido Glutationa Peroxidase/genética , Cultura Primária de Células , Carbonilação Proteica/imunologia , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/imunologia , Sulfonamidas/farmacologia , Células THP-1 , Replicação Viral/imunologia
16.
Nat Rev Mol Cell Biol ; 21(9): 501-521, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32424334

RESUMO

The cGAS-STING signalling axis, comprising the synthase for the second messenger cyclic GMP-AMP (cGAS) and the cyclic GMP-AMP receptor stimulator of interferon genes (STING), detects pathogenic DNA to trigger an innate immune reaction involving a strong type I interferon response against microbial infections. Notably however, besides sensing microbial DNA, the DNA sensor cGAS can also be activated by endogenous DNA, including extranuclear chromatin resulting from genotoxic stress and DNA released from mitochondria, placing cGAS-STING as an important axis in autoimmunity, sterile inflammatory responses and cellular senescence. Initial models assumed that co-localization of cGAS and DNA in the cytosol defines the specificity of the pathway for non-self, but recent work revealed that cGAS is also present in the nucleus and at the plasma membrane, and such subcellular compartmentalization was linked to signalling specificity of cGAS. Further confounding the simple view of cGAS-STING signalling as a response mechanism to infectious agents, both cGAS and STING were shown to have additional functions, independent of interferon response. These involve non-catalytic roles of cGAS in regulating DNA repair and signalling via STING to NF-κB and MAPK as well as STING-mediated induction of autophagy and lysosome-dependent cell death. We have also learnt that cGAS dimers can multimerize and undergo liquid-liquid phase separation to form biomolecular condensates that could importantly regulate cGAS activation. Here, we review the molecular mechanisms and cellular functions underlying cGAS-STING activation and signalling, particularly highlighting the newly emerging diversity of this signalling pathway and discussing how the specificity towards normal, damage-induced and infection-associated DNA could be achieved.


Assuntos
Proteínas de Membrana/metabolismo , Nucleotidiltransferases/metabolismo , Animais , Autofagia , AMP Cíclico/metabolismo , AMP Cíclico/fisiologia , GMP Cíclico/metabolismo , GMP Cíclico/fisiologia , Citosol/metabolismo , DNA/metabolismo , Humanos , Interferon Tipo I/genética , Interferon Tipo I/metabolismo , Proteínas de Membrana/fisiologia , Nucleotídeos Cíclicos , Nucleotidiltransferases/genética , Transdução de Sinais
17.
Am J Physiol Heart Circ Physiol ; 318(6): H1525-H1537, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32383996

RESUMO

Growing evidence shows that activation of inflammation in the heart provokes left ventricular (LV) remodeling and dysfunction in humans and experimental animals with heart failure (HF). Moreover, recent studies found that cyclic GMP-AMP synthase (cGAS), serving as a cytosolic DNA sensor, was essential for activating innate immunity against infection and cellular damage by initiating the STING-IRFs-type I IFN signaling cascade, which played important roles in regulating the inflammatory response. However, the pathophysiological role of cGAS in pressure overload-induced HF is unclear. Wild-type C57BL/6J mice and cGAS inhibition mice were subjected to transverse aortic constriction (TAC) to induce HF or sham operation. Inhibition of cGAS in the murine heart was performed using adeno-associated virus 9 (AAV9). Alterations of the cGAS/STING pathway were examined by qPCR and Western blotting. Cardiac remodeling was assessed by echocardiography as well as histological and molecular phenotyping. Compared with sham-operated mice, the cGAS/STING pathway was activated in LV tissues in TAC mice. Whereas TAC mice exhibited significant pathological cardiac remodeling and LV dysfunction, inhibition of cGAS improved early survival rates after TAC, preserved LV contractile function, and blunted pathological remodeling, including cardiac hypertrophy, fibrosis, and apoptosis. Furthermore, downregulation of cGAS diminished early inflammatory cell infiltration and inflammatory cytokine expression in response to TAC. These results demonstrated that cGAS played an essential pathogenetic role in pressure overload-induced HF to promote pathological cardiac remodeling and dysfunction. Our results suggest that inhibition of cGAS may be a novel therapeutic approach for HF.NEW & NOTEWORTHY In this study, we first revealed a novel role of cGAS in the regulation of pathological cardiac remodeling and dysfunction upon pressure overload. We found that the cGAS/STING pathway was activated during pressure overload. Moreover, we also demonstrated that inhibition of the cGAS/STING pathway alleviated pathological cardiac remodeling and downregulated the early inflammatory response during pressure overload-induced HF. Together, these findings will provide a new therapeutic target for HF.


Assuntos
Pressão Sanguínea/fisiologia , Insuficiência Cardíaca/metabolismo , Proteínas de Membrana/metabolismo , Nucleotidiltransferases/metabolismo , Remodelação Ventricular/fisiologia , Animais , Coração/fisiopatologia , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Transgênicos , Nucleotidiltransferases/genética , Transdução de Sinais
18.
Sci Rep ; 10(1): 7604, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32371942

RESUMO

The cGAS-STING pathway is a major mechanism that mammalian cells utilize to detect cytoplasmic dsDNA from incoming viruses, bacteria, or self. CYCLIC GMP-AMP SYNTHASE (cGAS) is the sensor protein that directly binds dsDNAs. cGAS synthesizes cyclic GMP-AMP (cGAMP), which binds to the adaptor STIMULATOR OF INTERFERON GENES (STING), activating an INTERFERON REGULATORY FACTOR 3 (IRF3)-mediated immune response. Constitutive activation can result in interferonopathies such as Aicardi-Goutieres Syndrome (AGS) or other lupus-like autoimmune disorders. While inhibitors targeting mouse or human cGAS have been reported, the identification of a small molecule that targets both homologs of cGAS has been challenging. Here, we show that RU.521 is capable of potently and selectively inhibiting mouse and human cGAS in cell lines and human primary cells. This inhibitory activity requires the presence of cGAS, but it cannot suppress an immune response in cells activated by RNA, Toll-like receptor ligands, cGAMP, or recombinant interferon. Importantly, when RU.521 is applied to cells, the production of dsDNA-induced intracellular cGAMP is suppressed in a dose-dependent manner. Our work validates the use of RU.521 for probing DNA-induced innate immune responses and underscores its potential as an ideal scaffold towards pre-clinical development, given its potency against human and mouse cGAS.


Assuntos
Citocinas/genética , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Nucleotídeos Cíclicos/metabolismo , Nucleotidiltransferases/antagonistas & inibidores , Animais , Benzofuranos/farmacologia , Linhagem Celular , Citocinas/metabolismo , Relação Dose-Resposta a Droga , Humanos , Imunomodulação/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Camundongos , Modelos Biológicos , Monócitos/efeitos dos fármacos , Monócitos/imunologia , Monócitos/metabolismo , Nucleotidiltransferases/metabolismo , Receptores de Reconhecimento de Padrão/genética , Receptores de Reconhecimento de Padrão/metabolismo , Transdução de Sinais/efeitos dos fármacos
19.
Cancer Cell ; 37(5): 720-734.e13, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32359397

RESUMO

Renal medullary carcinoma (RMC) is a highly lethal malignancy that mainly afflicts young individuals of African descent and is resistant to all targeted agents used to treat other renal cell carcinomas. Comprehensive genomic and transcriptomic profiling of untreated primary RMC tissues was performed to elucidate the molecular landscape of these tumors. We found that RMC was characterized by high replication stress and an abundance of focal copy-number alterations associated with activation of the stimulator of the cyclic GMP-AMP synthase interferon genes (cGAS-STING) innate immune pathway. Replication stress conferred a therapeutic vulnerability to drugs targeting DNA-damage repair pathways. Elucidation of these previously unknown RMC hallmarks paves the way to new clinical trials for this rare but highly lethal malignancy.


Assuntos
Biomarcadores Tumorais/metabolismo , Carcinoma Medular/patologia , Carcinoma de Células Renais/patologia , Aberrações Cromossômicas , Replicação do DNA , Neoplasias Renais/patologia , Proteína SMARCB1/metabolismo , Adulto , Animais , Apoptose , Biomarcadores Tumorais/genética , Carcinoma Medular/genética , Carcinoma Medular/imunologia , Carcinoma de Células Renais/genética , Carcinoma de Células Renais/imunologia , Proliferação de Células , Estudos de Coortes , Variações do Número de Cópias de DNA , Feminino , Regulação Neoplásica da Expressão Gênica , Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Neoplasias Renais/genética , Neoplasias Renais/imunologia , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Nus , Nucleotidiltransferases/genética , Nucleotidiltransferases/metabolismo , Prognóstico , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Proteína SMARCB1/genética , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
20.
J Phys Chem Lett ; 11(11): 4430-4435, 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32392072

RESUMO

The pandemic outbreak of a new coronavirus (CoV), SARS-CoV-2, has captured the world's attention, demonstrating that CoVs represent a continuous global threat. As this is a highly contagious virus, it is imperative to understand RNA-dependent-RNA-polymerase (RdRp), the key component in virus replication. Although the SARS-CoV-2 genome shares 80% sequence identity with severe acute respiratory syndrome SARS-CoV, their RdRps and nucleotidyl-transferases (NiRAN) share 98.1% and 93.2% identity, respectively. Sequence alignment of six coronaviruses demonstrated higher identity among their RdRps (60.9%-98.1%) and lower identity among their Spike proteins (27%-77%). Thus, a 3D structural model of RdRp, NiRAN, non-structural protein 7 (nsp7), and nsp8 of SARS-CoV-2 was generated by modeling starting from the SARS counterpart structures. Furthermore, we demonstrate the binding poses of three viral RdRp inhibitors (Galidesivir, Favipiravir, and Penciclovir), which were recently reported to have clinical significance for SARS-CoV-2. The network of interactions established by these drug molecules affirms their efficacy to inhibit viral RNA replication and provides an insight into their structure-based rational optimization for SARS-CoV-2 inhibition.


Assuntos
Betacoronavirus/enzimologia , Nucleotidiltransferases/química , /química , Adenina/análogos & derivados , Adenina/química , Adenina/metabolismo , Adenosina/análogos & derivados , Amidas/química , Amidas/metabolismo , Antivirais/química , Antivirais/metabolismo , Betacoronavirus/isolamento & purificação , Sítios de Ligação , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/patologia , Infecções por Coronavirus/virologia , Humanos , Simulação de Acoplamento Molecular , Nucleotidiltransferases/metabolismo , Pandemias , Pneumonia Viral/epidemiologia , Pneumonia Viral/patologia , Pneumonia Viral/virologia , Estrutura Terciária de Proteína , Pirazinas/química , Pirazinas/metabolismo , Pirrolidinas/química , Pirrolidinas/metabolismo , /metabolismo
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