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ABSTRACT:
PROVIDER: PRJNA1125631 | ENA |
REPOSITORIES: ENA
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Project description:The RIG-I-like receptors (RLRs: RIG-I, MDA5 and LGP2) trigger inflammatory and antiviral responses by sensing non-self RNA molecules produced during viral replication. LGP2 regulation of RIG-I and MDA5-dependant type-I interferon signaling is a matter of controversy. Here we show that LGP2 interacts with different components of the RNA silencing machinery. Particularly, we identified a direct protein-protein interaction between LGP2 and interferon-inducible double-stranded RNA-dependent protein kinase activator A (PACT). The LGP2-PACT interaction is mediated by the regulatory C-terminal domain of LGP2 and is necessary for inhibiting the RIG-I- and amplifying the MDA5-responses. We describe a point mutation within LGP2 that disrupts LGP2-PACT interaction and leads to the loss of LGP2 regulatory activity over RIG-I and MDA5. These results provide a model in which PACT-LGP2 interaction regulates RIG-I and MDA5 inflammatory response and allows cellular RNA silencing machinery to coordinate the innate immune response.
2019-10-02 | PXD013191 | Pride
Project description:Adenosine deaminases acting on RNA (Adar1 and Adar2) catalyze I-to-A RNA editing, a post-transcriptional mechanism involved in multiple cellular functions. The role of Adar1-dependent RNA editing in cardiomyocytes (CMs) remains unclear. Here we show that conditional deletion of Adar1 in CMs results in myocarditis progressively evolving into dilated cardiomyopathy and heart failure at only 6 months of age. Adar1 depletion drives activation of interferon signaling genes (ISGs) in the absence of apoptosis and cytokine activation, and reduces the hypertrophic response of CMs upon pressure overload. Interestingly, ablation of the cytosolic sensor MDA5 prevents cardiac ISG activation and delays disease onset, but does not rescue the long-term lethal phenotype elicited by conditional deletion of Adar1. Retention of a single catalytically inactive Adar1 allele in CMs, in combination with MDA5 depletion, however, completely restores the cardiac function and prevents heart failure. Finally, ablation of interferon regulatory factor 7 (Irf7) attenuates the phenotype of Adar1-deficient CMs to a similar extent as MDA5 depletion, highlighting Irf7 as the main regulator of the immune response triggered by lack of Adar1 in CMs.
2022-08-24 | PXD024974 | Pride
Project description:Adenosine deaminase acting on RNA (ADAR) (also known as ADAR1) promotes A-to-I conversion in double-stranded and highly structured RNAs. ADAR1 has two isoforms transcribed from different promoters: ADAR1p150, which is mainly cytoplasmic and interferon-inducible, and constitutively expressed ADAR1p110 that is primarily localized in the nucleus. Mutations in ADAR1 cause Aicardi – Goutières syndrome (AGS), a severe autoinflammatory disease in humans associated with aberrant IFN production. In mice, deletion of ADAR1 or selective knockout of the p150 isoform alone leads to embryonic lethality driven by overexpression of interferon-stimulated genes. This phenotype can be rescued by concurrent deletion of cytoplasmic dsRNA-sensor MDA5. These findings indicate that the interferon-inducible p150 isoform is indispensable and cannot be rescued by the ADAR1p110 isoform. Nevertheless, editing sites uniquely targeted by ADAR1p150 but also mechanisms of isoform- specificity remain elusive. To identify ADAR1 isoform-specific ‘editome’, we transfected A-to-I editing deficient mouse embryonic fibroblasts (MEFs) with ADAR1p150- or ADAR1p110- or RFP-editing negative control. We subjected the samples to RNA sequencing and detected editing at known-editing sites.
2021-11-17 | GSE188842 | GEO
Project description:Adenosine deaminase acting on RNA (ADAR) (also known as ADAR1) promotes A-to-I conversion in double-stranded and highly structured RNAs. ADAR1 has two isoforms transcribed from different promoters: ADAR1p150, which is mainly cytoplasmic and interferon-inducible, and constitutively expressed ADAR1p110 that is primarily localized in the nucleus. Mutations in ADAR1 cause Aicardi – Goutières syndrome (AGS), a severe autoinflammatory disease in humans associated with aberrant IFN production. In mice, deletion of ADAR1 or selective knockout of the p150 isoform alone leads to embryonic lethality driven by overexpression of interferon-stimulated genes. This phenotype can be rescued by concurrent deletion of cytoplasmic dsRNA-sensor MDA5. These findings indicate that the interferon-inducible p150 isoform is indispensable and cannot be rescued by the ADAR1p110 isoform. Nevertheless, editing sites uniquely targeted by ADAR1p150 but also mechanisms of isoform- specificity remain elusive. To examine in vivo interaction between ADAR1-isoforms and its substrates, we performed RNA immunoprecipitation and sequencing (RIP-seq) in HEK293 cells. RIP-seq experiment was done with overexpressed flag-tagged ADAR1 isoforms.
2021-11-19 | GSE188937 | GEO
Project description:The antiviral defense in vertebrates requires the innate immune system to sense foreign “non-self” nucleic acids while avoiding “self” nucleic acids, which is accomplished by an intricate system. Cellular double-stranded RNAs (dsRNAs) are edited by the RNA editing enzyme ADAR1 to prevent their dsRNA structure pattern from being recognized as viral dsRNA. Lack of RNA editing by ADAR1 enables activation of MDA5, a cytosolic dsRNA sensor, by cellular dsRNA. Additional RNA editing- independent functions of ADAR1 have been proposed, but the specific mechanism remains elusive. Here we demonstrate that RNA binding by ADAR1, independent of its editing activity, restricts the activation of PKR, another cytosolic dsRNA sensor, by cellular dsRNA. Mechanistically, the loss of ADAR1 editing caused MDA5 activation to induce interferon signaling, while a lack of ADAR1 protein or its dsRNA binding ability led to PKR activation, with subsequent stress granule formation and proliferation arrest. Based on these findings we rescued the Adar1−/− mice from embryonic lethality to adulthood by deleting both MDA5 and PKR, in contrast to the limited rescue of Adar1−/− mice by removing MDA5 or PKR alone. Our findings reveal a multifaceted contribution of ADAR1 in regulating the immunogenicity of “self” dsRNAs. Furthermore, ADAR1 is an immuno-oncology target for drug development, and the separation of ADAR1’s RNA editing and binding functions provides mechanistic insights for such developments.
2023-10-03 | GSE198386 | GEO
Project description:MDA5 is an innate immune RNA sensor that detects a range of viruses. MDA5’s RNA agonists are not well defined. We used individual-nucleotide resolution crosslinking and immunoprecipitation (iCLIP) to study its ligands. Surprisingly, upon infection with SARS-CoV-2 or encephalomyocarditis virus (EMCV), MDA5 bound overwhelmingly to cellular RNAs. Many binding sites were intronic and proximal to Alu elements. MDA5-bound RNA was enriched in Poly(A) and Poly(U) motifs, some of which may form double-stranded RNA. In EMCV-infected cells, cytoplasmic levels of intron-containing unspliced transcripts were increased, suggesting dysregulation of splicing. Concomitantly, MDA5 iCLIP peaks were enriched in introns accumulating in the cytoplasm of infected cells. Moreover, rescue of splicing abrogated MDA5 activation. Finally, depletion of viral RNA from RNA extracted from infected cells did not diminish its MDA5-stimulatory potential. Taken together, MDA5 surveys RNA processing fidelity and detects splicing perturbation during infection, establishing a paradigm of innate immune ‘guarding’ for RNA sensors.
2023-11-29 | GSE214663 | GEO
Project description:MDA5 is an innate immune RNA sensor that detects a range of viruses. MDA5’s RNA agonists are not well defined. We used individual-nucleotide resolution crosslinking and immunoprecipitation (iCLIP) to study its ligands. Surprisingly, upon infection with SARS-CoV-2 or encephalomyocarditis virus (EMCV), MDA5 bound overwhelmingly to cellular RNAs. Many binding sites were intronic and proximal to Alu elements. MDA5-bound RNA was enriched in Poly(A) and Poly(U) motifs, some of which may form double-stranded RNA. In EMCV-infected cells, cytoplasmic levels of intron-containing unspliced transcripts were increased, suggesting dysregulation of splicing. Concomitantly, MDA5 iCLIP peaks were enriched in introns accumulating in the cytoplasm of infected cells. Moreover, rescue of splicing abrogated MDA5 activation. Finally, depletion of viral RNA from RNA extracted from infected cells did not diminish its MDA5-stimulatory potential. Taken together, MDA5 surveys RNA processing fidelity and detects splicing perturbation during infection, establishing a paradigm of innate immune ‘guarding’ for RNA sensors.
2023-11-29 | GSE211240 | GEO
Project description:Dermatomyositis is a cutaneous and muscular auto-immune condition associated with specific autoantibodies. MDA5 antibody-associated DM has higher mortality. We demonstrate here for the first time using skin microarray analysis that MDA5+ DM is associated with a greater type I interferon skin signature than MDA5- DM, mainly involving the IFN- κ member produced by skin keratinocytes
2019-10-27 | GSE128314 | GEO
Project description:The transcription factor (TF) interferon regulatory factor 8 (IRF8) controls both developmental and inflammatory stimulus-inducible genes in macrophages, but the mechanisms underlying these two different functions are largely unknown. One possibility is that these different roles are linked to the ability of IRF8 to bind alternative DNA sequences. We found that IRF8 is recruited to distinct sets of DNA consensus sequences before and after lipopolysaccharide (LPS) stimulation. In resting cells, IRF8 was mainly bound to composite sites together with the master regulator of myeloid development PU.1. Basal IRF8M-bM-^@M-^SPU.1 binding maintained the expression of a broad panel of genes essential for macrophage functions (such as microbial recognition and response to purines) and contributed to basal expression of many LPS-inducible genes. After LPS stimulation, increased expression of IRF8, other IRFs, and AP-1 family TFs enabled IRF8 binding to thousands of additional regions containing low-affinity multimerized IRF sites and composite IRFM-bM-^@M-^SAP-1 sites, which were not premarked by PU.1 and did not contribute to the basal IRF8 cistrome. While constitutively expressed IRF8-dependent genes contained only sites mediating basal IRF8/PU.1 recruitment, inducible IRF8-dependent genes contained variable combinations of constitutive and inducible sites. Overall, these data show at the genome scale how the same TF can be linked to constitutive and inducible gene regulation via distinct combinations of alternative DNA-binding sites. Chromatin immuno-precipitations of transcription factors IRF8, IRF1, PU.1, STAT1, STAT2 and of H3 lysine 27 acetylated followed by multiparallel sequencing, performed in bone marrow-derived macrophages from wild type (WT) and BXH2/TyJ mice. Cells were treated with lipopolysaccharide (LPS) for 2 or 4 hours, or interferon b (IFNb) for 30 or 60 minutes, 2 or 4 hours, or left unstimulated.
2015-01-30 | E-GEOD-56121 | biostudies-arrayexpress
Project description:Retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), including RIG-I (encoded by Ddx58) and MDA5 (melanoma-differentiation-associated gene 5, encoded by Ifih1), are crucial for initiating antiviral responses. Endogenous retroviral elements (ERVs) are transposable elements derived from exogenous retrovirus that integrated into the genome. KRAB-associated protein 1 (KAP1) is a master epigenetic suppressor of ERVs, and thereby protects cells from detrimental genome instability. Increased ERV transcripts are sensed by RLRs and trigger innate immune signaling. However, whether KAP1 could directly control RLRs activity remain unclear. Here we show that KAP1 attenuates RNA viral infection induced type I IFNs and facilitates viral replication by inhibiting RIG-I/MDA5 expression in primary peritoneal macrophages of C57BL/6J mice. Kap1 deficiency increased IFN-β expression and inhibited VSV replication in C57BL/6J mice in vivo. Mechanistically, KAP1 binds to the promoter regions of Ddx58 and Ifih1, and promotes the establishment of repressive histone marks in primary peritoneal macrophages of C57BL/6J mice. Concordantly, KAP1 suppresses the expression of RIG-I and MDA5 at transcriptional level in primary peritoneal macrophages of C57BL/6J mice. Our results establish that KAP1 epigenetically suppresses host antiviral responses by direct targeting RIG-1 and MDA5, and thus facilitates the immune escape of RNA viruses.
2021-07-28 | GSE178443 | GEO