RESUMO
In mammals, cyclic GMP-AMP (cGAMP) synthase (cGAS) produces the cyclic dinucleotide 2'3'-cGAMP in response to cytosolic DNA and this triggers an antiviral immune response. cGAS belongs to a large family of cGAS/DncV-like nucleotidyltransferases that is present in both prokaryotes1 and eukaryotes2-5. In bacteria, these enzymes synthesize a range of cyclic oligonucleotides and have recently emerged as important regulators of phage infections6-8. Here we identify two cGAS-like receptors (cGLRs) in the insect Drosophila melanogaster. We show that cGLR1 and cGLR2 activate Sting- and NF-κB-dependent antiviral immunity in response to infection with RNA or DNA viruses. cGLR1 is activated by double-stranded RNA to produce the cyclic dinucleotide 3'2'-cGAMP, whereas cGLR2 produces a combination of 2'3'-cGAMP and 3'2'-cGAMP in response to an as-yet-unidentified stimulus. Our data establish cGAS as the founding member of a family of receptors that sense different types of nucleic acids and trigger immunity through the production of cyclic dinucleotides beyond 2'3'-cGAMP.
Assuntos
Drosophila melanogaster/imunologia , Nucleotidiltransferases/imunologia , Receptores de Reconhecimento de Padrão/metabolismo , Vírus/imunologia , Sequência de Aminoácidos , Animais , Linhagem Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Drosophila melanogaster/virologia , Feminino , Humanos , Imunidade Inata/genética , Imunidade Inata/imunologia , Ligantes , Masculino , Proteínas de Membrana/metabolismo , Modelos Moleculares , NF-kappa B/metabolismo , Nucleotídeos Cíclicos/metabolismo , Nucleotidiltransferases/classificação , Nucleotidiltransferases/deficiência , Nucleotidiltransferases/metabolismo , RNA de Cadeia Dupla/análise , RNA de Cadeia Dupla/imunologia , RNA de Cadeia Dupla/metabolismo , Receptores de Reconhecimento de Padrão/classificação , Receptores de Reconhecimento de Padrão/deficiência , Receptores de Reconhecimento de Padrão/imunologiaRESUMO
We previously reported that an ortholog of STING regulates infection by picorna-like viruses in Drosophila In mammals, STING is activated by the cyclic dinucleotide 2'3'-cGAMP produced by cGAS, which acts as a receptor for cytosolic DNA. Here, we showed that injection of flies with 2'3'-cGAMP induced the expression of dSTING-regulated genes. Coinjection of 2'3'-cGAMP with a panel of RNA or DNA viruses resulted in substantially reduced viral replication. This 2'3'-cGAMP-mediated protection was still observed in flies with mutations in Atg7 and AGO2, genes that encode key components of the autophagy and small interfering RNA pathways, respectively. By contrast, this protection was abrogated in flies with mutations in the gene encoding the NF-κB transcription factor Relish. Transcriptomic analysis of 2'3'-cGAMP-injected flies revealed a complex response pattern in which genes were rapidly induced, induced after a delay, or induced in a sustained manner. Our results reveal that dSTING regulates an NF-κB-dependent antiviral program that predates the emergence of interferons in vertebrates.
