{"gene":"IFIH1","run_date":"2026-06-10T01:55:22","timeline":{"discoveries":[{"year":2006,"finding":"MDA5 (IFIH1) recognizes long poly(I:C) dsRNA and is specifically required for innate immune detection of picornaviruses, while RIG-I detects in vitro-transcribed short dsRNAs and other RNA viruses; MDA5-/- mice are highly susceptible to picornavirus infection, establishing distinct and non-redundant roles for each helicase.","method":"MDA5 knockout mice, in vivo viral challenge, type I IFN production assays","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout mice with defined viral-challenge phenotype, independently confirmed in multiple follow-up studies across labs","pmids":["16625202"],"is_preprint":false},{"year":2007,"finding":"IPS-1/MAVS is an essential downstream adaptor for both RIG-I and MDA5 antiviral signaling; MDA5 is individually dispensable for innate immune signaling triggered by reovirus and dengue virus in cultured fibroblasts, but RIG-I is essential for influenza A, influenza B, and RSV.","method":"siRNA knockdown of RIG-I, MDA5, and IPS-1 in cultured fibroblasts; IRF3 activation and ISG expression assays","journal":"Journal of virology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (siRNA, functional genomics, IRF3 activation), replicated across multiple virus systems","pmids":["17942531"],"is_preprint":false},{"year":2007,"finding":"MDA5 protein is degraded in poliovirus-infected cells via a proteasome- and caspase-dependent mechanism (not by viral proteinases 2Apro or 3Cpro), correlating with apoptosis induction; this degradation is proposed as a viral strategy to antagonize type I IFN production.","method":"Western blot, proteasome inhibitors, caspase inhibitors, proteinase-mutant viruses, puromycin-induced apoptosis controls","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple inhibitor approaches in single lab establishing mechanism of degradation","pmids":["17267501"],"is_preprint":false},{"year":2015,"finding":"ADAR1-mediated A-to-I editing of endogenous dsRNA stem-loop structures in 3' UTRs of cellular transcripts is required to prevent MDA5 from sensing endogenous dsRNA as nonself; concurrent deletion of MDA5 rescues the embryonic lethality of editing-deficient Adar1(E861A/E861A) mice.","method":"Editing-deficient knock-in mice (Adar1 E861A), MDA5 double-knockout rescue, genome-wide RNA editing substrate identification","journal":"Science","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — genetic epistasis with double-knockout rescue, genome-wide substrate mapping, replicated in subsequent independent studies","pmids":["26275108"],"is_preprint":false},{"year":2015,"finding":"TRIM65 specifically interacts with MDA5 and catalyzes K63-linked ubiquitination of MDA5 at lysine 743, which is required for MDA5 oligomerization and activation; Trim65-/- mice cannot produce type I IFN and are more susceptible to EMCV infection.","method":"Co-immunoprecipitation, ubiquitination assays, Trim65-/- knockout mice, EMCV challenge, IRF3 activation assays","journal":"The Journal of experimental medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, site-specific ubiquitination mapping, in vivo knockout phenotype with clean viral challenge","pmids":["28031478"],"is_preprint":false},{"year":2018,"finding":"Constitutive activation of MDA5 in Aicardi-Goutières syndrome results from loss of tolerance to Alu retroelement-derived dsRNAs; AGS-associated MDA5 variants display reduced sensitivity to duplex structural irregularities and can form signaling-competent filaments on imperfect Alu-dsRNAs, whereas wild-type MDA5 cannot efficiently recognize them.","method":"RNase-protection/RNA-seq approach to identify endogenous MDA5 ligands; functional analysis of AGS variants; MDA5 filament assembly assays on Alu-dsRNAs","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (RNA-seq, biochemical filament assays, functional variant analysis) in single rigorous study","pmids":["29395326"],"is_preprint":false},{"year":2015,"finding":"An IFIH1 gain-of-function missense mutation (p.Arg822Gln) causes Singleton-Merten syndrome by enhancing MDA5 function in IFN-β induction; in vitro functional analysis confirmed enhanced MDA5-mediated interferon signaling; interferon signature genes were upregulated in SMS patient blood and dental cells.","method":"Whole-exome sequencing, in vitro IFN-β induction assays with mutant IFIH1, immunohistochemistry, interferon signature gene expression","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro functional assay confirming gain-of-function, supported by patient gene expression data; single lab","pmids":["25620204"],"is_preprint":false},{"year":2017,"finding":"PACT (dsRNA-binding protein) functions as an essential coactivator of MDA5 by promoting dsRNA-induced oligomerization of MDA5; PACT-knockout cells show severely impaired virus- and poly(I:C)-induced MDA5-dependent type I IFN responses; PACT had no influence on MDA5-mediated NF-κB activation and required dsRNA interaction for its action.","method":"PACT knockout and knockdown cells, overexpression, oligomerization assays, IRF3-dependent IFN assays, colocalization studies","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockout and overexpression with multiple functional readouts, single lab","pmids":["28760879"],"is_preprint":false},{"year":2020,"finding":"LGP2 facilitates MDA5 filament assembly by acting as a nucleator; LGP2 is incorporated into MDA5-dsRNA filaments (average inter-molecular distance ~32 nm), induces conformational changes in MDA5 promoting CARD domain exposure, and promotes conversion of MDA5 to an active conformation capable of downstream signaling even after filament dissociation by ATP hydrolysis.","method":"Biochemical filament assembly assays, biophysical approaches, limited protease digestion, ATP hydrolysis assays","journal":"Nucleic acids research","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — multiple biophysical and biochemical methods in single lab; no independent replication cited","pmids":["33137199"],"is_preprint":false},{"year":2021,"finding":"The disease-associated MDA5 variant M854K lacks ATPase activity, binds more stably to Alu:Alu dsRNA, and constitutively activates interferon signaling in the absence of exogenous RNA; cryo-EM structures of MDA5-dsRNA filaments reveal that K854 forms polar bonds constraining subdomain conformation and disrupting key steps in the ATPase cycle (RNA footprint expansion and helical twist modulation), inhibiting ATP-dependent RNA proofreading via an allosteric mechanism.","method":"CryoEM structural determination, ATPase activity assays, dsRNA binding assays, interferon signaling reporter assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cryo-EM structure with functional mutagenesis and biochemical validation in single rigorous study","pmids":["34795277"],"is_preprint":false},{"year":2024,"finding":"Adjacent MDA5 subunits in MDA5-dsRNA filaments hydrolyze ATP cooperatively, inducing cooperative filament disassembly; consecutive rounds of ATP hydrolysis amplify the filament footprint; LGP2 binds dsRNA at internal sites via noncooperative ATP hydrolysis, has low nucleic acid selectivity (can hydrolyze GTP and CTP as well as ATP), promotes MDA5 filament nucleation yielding shorter filaments, and makes key contacts with MDA5 via its C-terminal tail.","method":"Electron microscopy, biochemical ATPase assays, nucleotide specificity assays, filament assembly assays, molecular modeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — EM structural data combined with multiple orthogonal biochemical assays in single rigorous study","pmids":["38309507"],"is_preprint":false},{"year":2019,"finding":"Enterovirus 71 RNA-dependent RNA polymerase (3Dpol) interacts specifically with the CARD domains of MDA5 and inhibits MDA5-mediated IFN-β promoter activation; coxsackievirus B3 3Dpol also interacts with MDA5 and downregulates MDA5-initiated antiviral signaling.","method":"Co-immunoprecipitation, reporter assays for IFN-β promoter activation, pulldown assays","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP and functional reporter assays, two viruses tested, single lab","pmids":["30814289"],"is_preprint":false},{"year":2018,"finding":"EMCV non-structural protein 2C interacts with MDA5 to inhibit IFN-β signaling; mutation of amino acid V26 of 2C abolishes both IFN-β inhibition and MDA5 interaction; rescued viruses with 2C mutations induce significantly higher IFN-β levels.","method":"Co-immunoprecipitation, site-directed mutagenesis, reverse genetics (rescued virus), IFN-β reporter and mRNA assays","journal":"Antiviral research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis combined with reverse genetics and functional assays, single lab","pmids":["30312637"],"is_preprint":false},{"year":2019,"finding":"MDA5 2CARD self-associates into large oligomers in a concentration-dependent manner in the absence of polyubiquitin, whereas RIG-I 2CARD requires unanchored K63-linked polyubiquitin for tetramerization; polyubiquitin (Ub4) binds MDA5 2CARD only weakly (1:1 and 2:1 stoichiometries) and does not induce 2CARD oligomerization, indicating distinct assembly mechanisms for RIG-I and MDA5 signaling.","method":"Sedimentation velocity analytical ultracentrifugation, multi-signal sedimentation velocity analysis","journal":"Protein science","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous biophysical method (AUC), single lab, no independent replication","pmids":["31697400"],"is_preprint":false},{"year":2021,"finding":"MDA5 is required for type I and type III IFN induction in lung epithelial cells (Calu-3) upon SARS-CoV-2 infection; this IFN induction further requires MAVS and IRF3; induction of IL-6 and TNF by SARS-CoV-2 is independent of the MDA5-MAVS-IRF3 axis.","method":"siRNA knockdown of MDA5, MAVS, IRF3; IFN and cytokine production assays in SARS-CoV-2-infected Calu-3 cells","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with multiple pathway components tested, replicated with multiple target knockdowns in single study","pmids":["34211037"],"is_preprint":false},{"year":2022,"finding":"SARS-CoV-2 2'-O-methyltransferase Nsp16 shields viral RNA from MDA5-mediated recognition; recombinant SARS-CoV-2 with catalytically inactive Nsp16 (Nsp16mut) is highly immunogenic with strongly enhanced type I IFN release, and this elevated immunogenicity is absent in MDA5-deficient cells.","method":"Recombinant virus with Nsp16 catalytic mutant, MDA5 knockout cells, IFN production assays","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — recombinant virus combined with genetic knockout, single lab","pmids":["36285486"],"is_preprint":false},{"year":2023,"finding":"SARS-CoV-2 nonstructural protein Nsp8 binds to both MDA5 and TRIM4, impairing TRIM4-mediated K63-linked polyubiquitination of MDA5, thereby suppressing MDA5 activation and downstream IRF3/NF-κB signaling and IFN production.","method":"Co-immunoprecipitation, ubiquitination assays, IFN reporter assays, SARS-CoV-2 infection studies","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP with functional ubiquitination assays and IFN readouts; single lab","pmids":["37956198"],"is_preprint":false},{"year":2020,"finding":"ZFYVE1 specifically interacts with MDA5 (not RIG-I), binds viral RNA, and decreases MDA5 ligand binding and oligomerization, functioning as a specific negative regulator of MDA5-mediated (but not RIG-I-mediated) innate antiviral responses; Zfyve1-/- mice are protected from EMCV (MDA5-sensed) but not VSV (RIG-I-sensed) lethality.","method":"Co-immunoprecipitation, Zfyve1-/- knockout mice, viral challenge (EMCV and VSV), MDA5 oligomerization and ligand-binding assays","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, in vivo knockout with two virus challenge systems, biochemical oligomerization assays","pmids":["32251420"],"is_preprint":false},{"year":2024,"finding":"IFIH1 (MDA5) is the innate immune receptor required for detection of intron-containing RNA from the HIV-1 provirus in primary human dendritic cells; MDA5 filament formation, dephosphorylation, and association with MAVS are all required for innate immune activation; MDA5 specifically enriches unspliced HIV-1 RNA over two orders of magnitude as shown by formaldehyde cross-linking immunoprecipitation (f-CLIP); DDX58/RIG-I knockdown had no effect.","method":"shRNA loss-of-function screen, nontargetable IFIH1 rescue, Nipah virus V protein inhibitor, dominant-negative IFIH1 mutants, f-CLIP RNA immunoprecipitation, RNA-Seq","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (shRNA screen, rescue, dominant-negative mutants, specific inhibitor, f-CLIP), single rigorous study","pmids":["38985764"],"is_preprint":false},{"year":2023,"finding":"Loss of ADAR1p150 activates both MDA5 and PKR; deleting both MDA5 and PKR completely rescues the embryonic lethality of Adar1p150-/- mice to adulthood, whereas removing MDA5 or PKR alone provides only limited or no rescue; loss of ADAR1-mediated RNA editing specifically activates MDA5, whereas loss of cytoplasmic ADAR1p150 or its dsRNA-binding activity enables PKR activation.","method":"Adar1p150-/- knockout mice, MDA5/PKR double-knockout epistasis, rescue experiments, survival analysis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — rigorous genetic epistasis with double-knockout rescue, clearly delineating MDA5 vs PKR roles downstream of ADAR1","pmids":["37797622"],"is_preprint":false},{"year":2021,"finding":"Transposable element transcripts (ERV and LINE superfamily copies) generated during chemotherapy-induced chromatin reorganization bind to and activate MDA5 in haematopoietic stem cells (HSCs), generating an inflammatory response required for HSC exit from quiescence; Mda5-/- HSCs retain quiescence and show better long-term repopulation after chemotherapy.","method":"Mda5-/- knockout mice, chemotherapy challenge, chromatin reorganization analysis, TE transcript overexpression/knockdown, HSC quiescence and repopulation assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean knockout mice with defined cellular phenotype, supported by TE overexpression/knockdown experiments","pmids":["34253898"],"is_preprint":false},{"year":2024,"finding":"RNF144B specifically interacts with MDA5 CARDs and promotes K27/K33-linked polyubiquitination of MDA5 at lysine 23 and 43, which promotes autophagic degradation of MDA5 via p62; Rnf144b-/- mice show greatly enhanced IFN production and significantly higher survival upon EMCV infection.","method":"Co-immunoprecipitation, ubiquitination mapping, Rnf144b-/- knockout mice, EMCV challenge, p62-mediated autophagy assays","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — site-specific ubiquitination, in vivo knockout with viral challenge, mechanistic autophagy pathway validation","pmids":["39285245"],"is_preprint":false},{"year":2022,"finding":"Flavivirus prM protein from TBEV interacts with both MDA5 and MAVS, interfering with MDA5-MAVS complex formation and thereby impeding IRF3 nuclear translocation/dimerization and inhibiting RLR antiviral signaling; ZIKV and WNV prM similarly interact with both MDA5 and MAVS.","method":"Co-immunoprecipitation, IRF3 localization assays, IFN-I reporter assays, viral replication assays","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-IP with functional IFN reporter readout, single lab, multiple flaviviruses tested","pmids":["36639652"],"is_preprint":false},{"year":2022,"finding":"Transgenic mice expressing human MDA5 R779H mutant spontaneously develop myocarditis and nephritis with upregulated type I IFNs; cardiomyocyte-specific expression of hMDA5 R779H causes cardiomegaly and inflammatory cytokine upregulation; the phenotype requires intact MDA5-MAVS signaling and IFNAR (R779H Tg Mavs-/- and R779H Tg Ifnar-/- mice show no phenotype).","method":"Transgenic mice (whole-body and cardiomyocyte-specific), MAVS-/- and IFNAR-/- double knockouts, bone marrow transplantation, histopathology","journal":"Journal of autoimmunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific transgenic expression combined with MAVS/IFNAR double-knockout epistasis","pmids":["35168003"],"is_preprint":false},{"year":2021,"finding":"IFIH1 promotes IRF3 nuclear translocation in macrophages via a MyD88-dependent mechanism when stimulated by LPS, in addition to its known RNA-sensing role; IFIH1 knockdown abolishes LPS-induced IRF3 activation and M1 polarization in RAW264.7 and BMDM cells.","method":"shRNA knockdown, IFIH1 overexpression lentiviral constructs, macrophage polarization assays, IRF3 activation measurements, GSEA","journal":"Frontiers in immunology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single primary cell type, limited mechanistic follow-up on the LPS/MyD88-IFIH1-IRF3 axis","pmids":["33519803"],"is_preprint":false},{"year":2025,"finding":"Immunogenic dsRNAs that activate MDA5 constitute a small fraction of all cellular dsRNAs, are highly enriched in mRNAs and depleted of introns (consistent with cytosolic localization), and their MDA5-dependent immunogenicity is dampened by ADAR1-mediated RNA editing.","method":"Transcriptomic/RNA-seq identification of immunogenic dsRNAs, MDA5-dependent immunogenicity validation, ADAR1 editing correlation analysis","journal":"Nature genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genome-wide identification with MDA5-dependent functional validation, single study","pmids":["41339703"],"is_preprint":false},{"year":2011,"finding":"Overexpression of Ifih1 (MDA5) in transgenic mice leads to a chronic type I IFN state with viral resistance; spontaneous MDA5 activation alone is not sufficient to initiate autoimmune or inflammatory pathology, but accelerates autoantibody production, glomerulonephritis, and early lethality on an FcγR2B-deficient lupus-susceptible background.","method":"Ifih1 multi-copy transgenic mice, viral challenge, autoimmune phenotyping, FcγR2B-deficient cross","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transgenic overexpression with defined phenotypic readouts and genetic crosses, single lab","pmids":["22205024"],"is_preprint":false},{"year":2020,"finding":"IFIH1 gain-of-function mutations cluster near the ATP-binding region of MDA5 and are associated with either increased RNA-binding affinity or decreased ATP hydrolysis efficiency and filament disassembly rate, establishing a common mutational mechanism for type I interferonopathies.","method":"Cohort genetic analysis with in vitro functional characterization of 27 mutations; ATP hydrolysis and RNA-binding assays","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional in vitro assays on multiple variants combined with large cohort genetic data","pmids":["31898846"],"is_preprint":false}],"current_model":"MDA5 (IFIH1) is a cytoplasmic dsRNA sensor that forms cooperative helical filaments on long dsRNA substrates (preferentially viral dsRNA, including from picornaviruses, SARS-CoV-2, and HIV-1 intron-containing RNA), activating type I interferon signaling via its tandem CARD domains through MAVS; its ATPase activity fulfills an essential RNA-proofreading function that promotes dissociation from shorter endogenous dsRNAs while retaining longer viral dsRNAs, and this selectivity is disrupted by disease-associated gain-of-function mutations that allow recognition of endogenous Alu-element dsRNAs; activation requires TRIM65-mediated K63-linked ubiquitination at Lys743 for oligomerization, is enhanced by co-activators PACT and LGP2 (which acts as a nucleator promoting CARD exposure), and is negatively regulated by ZFYVE1 (inhibiting ligand binding/oligomerization) and RNF144B (promoting K27/K33-ubiquitination and autophagic degradation); ADAR1-mediated A-to-I editing of endogenous dsRNAs is the primary mechanism preventing MDA5 from triggering fatal autoinflammation in normal cells."},"narrative":{"mechanistic_narrative":"IFIH1 (MDA5) is a cytoplasmic sensor of long double-stranded RNA that initiates type I and type III interferon responses, providing non-redundant antiviral immunity against picornaviruses and a range of other pathogens [PMID:16625202, PMID:17942531, PMID:34211037]. Upon engaging long dsRNA, MDA5 assembles cooperative helical filaments along the RNA, a process that exposes its tandem N-terminal CARD domains to nucleate signaling through the mitochondrial adaptor MAVS and drive IRF3 activation [PMID:29395326, PMID:38985764, PMID:35168003]. Filament-based activation is gated by an ATP-dependent RNA-proofreading function: adjacent subunits hydrolyze ATP cooperatively to disassemble filaments on shorter or imperfect duplexes while retaining longer bona fide viral dsRNA, conferring ligand selectivity [PMID:34795277, PMID:38309507]. Productive signaling additionally requires TRIM65-catalyzed K63-linked ubiquitination of MDA5 at Lys743 for oligomerization, and is augmented by the co-activator PACT and by LGP2, which nucleates MDA5 filament assembly and promotes the active CARD-exposed conformation [PMID:28031478, PMID:28760879, PMID:33137199]. MDA5 activity is restrained by ZFYVE1, which suppresses ligand binding and oligomerization, and by RNF144B, which directs K27/K33-linked ubiquitination and p62-dependent autophagic degradation [PMID:32251420, PMID:39285245]. Tolerance to self is enforced by ADAR1-mediated A-to-I editing of endogenous dsRNAs, principally Alu-element and mRNA-derived stem-loops; loss of editing or gain-of-function MDA5 variants that recognize imperfect endogenous duplexes drive constitutive interferon production [PMID:26275108, PMID:29395326, PMID:37797622, PMID:41339703]. Such variants cause type I interferonopathies including Aicardi-Goutières syndrome and Singleton-Merten syndrome, with mutations clustering near the ATP-binding region to increase RNA affinity or impair ATP-dependent disassembly [PMID:29395326, PMID:25620204, PMID:34795277, PMID:31898846]. Diverse viral proteins antagonize this pathway by targeting MDA5 directly or its activating ubiquitination, and MDA5 also senses endogenous transposable-element transcripts to regulate hematopoietic stem cell quiescence [PMID:30814289, PMID:37956198, PMID:34253898].","teleology":[{"year":2006,"claim":"Established MDA5 as a distinct, non-redundant innate sensor by showing it is specifically required to detect picornaviruses, separating its function from RIG-I.","evidence":"MDA5 knockout mice with in vivo viral challenge and type I IFN assays","pmids":["16625202"],"confidence":"High","gaps":["Did not define the molecular ligand features distinguishing MDA5 from RIG-I substrates","Downstream adaptor not yet identified"]},{"year":2007,"claim":"Placed MDA5 in a defined signaling pathway by identifying MAVS/IPS-1 as the shared essential downstream adaptor and mapping virus-specific sensor usage.","evidence":"siRNA knockdown of RIG-I, MDA5, IPS-1 in fibroblasts with IRF3/ISG readouts","pmids":["17942531"],"confidence":"High","gaps":["Mechanism of MDA5-MAVS coupling not resolved","Cell-type dependence of sensor requirements unclear"]},{"year":2007,"claim":"Showed that picornaviruses actively antagonize MDA5 through proteasome- and caspase-dependent degradation, framing the sensor as a target of viral immune evasion.","evidence":"Western blot with proteasome/caspase inhibitors and proteinase-mutant viruses in poliovirus-infected cells","pmids":["17267501"],"confidence":"Medium","gaps":["Identity of the responsible E3 ligase/protease not determined","Single-lab mechanistic inference"]},{"year":2015,"claim":"Defined the self/nonself discrimination problem by showing ADAR1 editing of endogenous dsRNA prevents MDA5 from sensing self, with MDA5 deletion rescuing editing-deficient lethality.","evidence":"Adar1 E861A editing-deficient knock-in mice with MDA5 double-knockout rescue and genome-wide substrate mapping","pmids":["26275108"],"confidence":"High","gaps":["Did not establish which specific endogenous RNAs trigger MDA5","PKR contribution not yet separated"]},{"year":2015,"claim":"Identified the activating post-translational switch by demonstrating TRIM65-mediated K63 ubiquitination at Lys743 is required for MDA5 oligomerization and antiviral function.","evidence":"Reciprocal Co-IP, site-specific ubiquitination mapping, Trim65-/- mice with EMCV challenge","pmids":["28031478"],"confidence":"High","gaps":["How ubiquitination couples to filament/CARD assembly not structurally resolved","Regulation of TRIM65 recruitment unknown"]},{"year":2015,"claim":"Connected MDA5 gain-of-function directly to human disease, showing the p.Arg822Gln variant enhances IFN-beta induction and causes Singleton-Merten syndrome.","evidence":"Whole-exome sequencing, in vitro IFN-beta induction assays, patient interferon signature analysis","pmids":["25620204"],"confidence":"Medium","gaps":["Structural basis of enhanced signaling not defined","Tissue specificity of pathology unexplained"]},{"year":2015,"claim":"Elucidated the activation mechanism of CARD signaling, showing MDA5 2CARD self-oligomerizes concentration-dependently without polyubiquitin, unlike RIG-I.","evidence":"Sedimentation velocity analytical ultracentrifugation of 2CARD with/without Ub4","pmids":["31697400"],"confidence":"Medium","gaps":["Reconciliation with TRIM65 ubiquitin requirement in cells not addressed","Single-lab biophysical study"]},{"year":2018,"claim":"Identified the endogenous immunogenic ligand class by showing Alu retroelement dsRNAs activate MDA5 in AGS and that disease variants form filaments on imperfect duplexes wild-type MDA5 cannot.","evidence":"RNase-protection/RNA-seq ligand identification, AGS variant functional analysis, filament assembly assays","pmids":["29395326"],"confidence":"High","gaps":["Quantitative threshold of duplex imperfection tolerated not defined","Relationship to ATPase proofreading not yet structurally linked"]},{"year":2018,"claim":"Extended the viral antagonism map by showing EMCV 2C binds MDA5 to suppress IFN-beta, validated by reverse genetics with a single residue determinant.","evidence":"Co-IP, V26 site-directed mutagenesis, rescued-virus reverse genetics, IFN-beta assays","pmids":["30312637"],"confidence":"Medium","gaps":["Step in MDA5 activation blocked by 2C not pinpointed","Single-lab study"]},{"year":2019,"claim":"Identified the CARD domain as a viral target by showing picornaviral 3Dpol polymerases bind MDA5 CARDs to inhibit IFN-beta induction.","evidence":"Co-IP, pulldown, IFN-beta promoter reporter assays for EV71 and CVB3","pmids":["30814289"],"confidence":"Medium","gaps":["Whether 3Dpol blocks oligomerization or MAVS coupling unclear","No in vivo validation"]},{"year":2020,"claim":"Defined LGP2 as a positive regulator acting as a filament nucleator that drives MDA5 into an active CARD-exposed conformation.","evidence":"Biochemical filament assembly, limited proteolysis, ATP hydrolysis assays","pmids":["33137199"],"confidence":"Medium","gaps":["In vivo significance of nucleation not established","Single-lab biochemical study"]},{"year":2020,"claim":"Identified ZFYVE1 as a sensor-specific negative regulator restraining MDA5 ligand binding and oligomerization in vivo.","evidence":"Reciprocal Co-IP, Zfyve1-/- mice with EMCV and VSV challenge, oligomerization/ligand-binding assays","pmids":["32251420"],"confidence":"High","gaps":["Structural basis of ZFYVE1-MDA5 inhibition not resolved","Regulation of ZFYVE1 itself unknown"]},{"year":2020,"claim":"Established a unifying mutational mechanism for interferonopathies by showing IFIH1 GOF variants cluster near the ATP-binding region and either raise RNA affinity or slow ATP hydrolysis/filament disassembly.","evidence":"Cohort genetics with in vitro ATP hydrolysis and RNA-binding assays on 27 variants","pmids":["31898846"],"confidence":"Medium","gaps":["Did not provide structural mechanism for individual variants","Genotype-phenotype severity correlation incomplete"]},{"year":2021,"claim":"Provided the structural mechanism of ATP-dependent proofreading, showing the M854K variant disrupts the ATPase cycle allosterically to stabilize binding on Alu:Alu dsRNA and constitutively signal.","evidence":"Cryo-EM of MDA5-dsRNA filaments, ATPase and dsRNA-binding assays, IFN reporter assays","pmids":["34795277"],"confidence":"High","gaps":["Generality of the allosteric mechanism across all GOF variants not tested","Dynamics of filament turnover in cells not captured"]},{"year":2021,"claim":"Extended MDA5's antiviral role to SARS-CoV-2, establishing it as the sensor driving type I/III IFN via MAVS-IRF3 in lung epithelium.","evidence":"siRNA knockdown of MDA5/MAVS/IRF3 in infected Calu-3 cells with IFN/cytokine assays","pmids":["34211037"],"confidence":"Medium","gaps":["Identity of activating SARS-CoV-2 RNA species not defined here","Knockdown rather than knockout system"]},{"year":2021,"claim":"Revealed a physiological role beyond infection, showing MDA5 senses chemotherapy-induced transposable-element transcripts to drive HSC exit from quiescence.","evidence":"Mda5-/- mice, chemotherapy challenge, TE transcript manipulation, HSC quiescence/repopulation assays","pmids":["34253898"],"confidence":"High","gaps":["Mechanism linking TE sensing to quiescence exit incompletely defined","Whether other stresses engage the same axis unknown"]},{"year":2022,"claim":"Demonstrated in vivo causality of an MDA5 GOF variant for organ-specific autoimmunity, with phenotype strictly dependent on MAVS and IFNAR.","evidence":"Whole-body and cardiomyocyte-specific hMDA5 R779H transgenic mice with MAVS-/- and IFNAR-/- crosses","pmids":["35168003"],"confidence":"High","gaps":["Endogenous RNA ligand driving the in vivo phenotype not identified","Basis of tissue-specific susceptibility unclear"]},{"year":2022,"claim":"Expanded viral evasion strategies, showing flavivirus prM proteins disrupt MDA5-MAVS complex formation and that SARS-CoV-2 Nsp16 methylation shields viral RNA from MDA5.","evidence":"Co-IP and IRF3 localization assays (prM); recombinant Nsp16-mutant virus in MDA5-KO cells","pmids":["36639652","36285486"],"confidence":"Medium","gaps":["Structural detail of complex disruption not resolved","Single-lab studies"]},{"year":2023,"claim":"Separated the ADAR1 effector pathways, showing loss of editing specifically activates MDA5 whereas loss of cytoplasmic ADAR1p150 dsRNA-binding activates PKR.","evidence":"Adar1p150-/- mice with MDA5/PKR double-knockout epistasis and survival analysis","pmids":["37797622"],"confidence":"High","gaps":["Whether MDA5 and PKR sense overlapping or distinct RNA pools unresolved","Crosstalk between the two effectors not defined"]},{"year":2023,"claim":"Identified a SARS-CoV-2 evasion mechanism converging on MDA5 ubiquitination, showing Nsp8 sequesters TRIM4 to block K63-ubiquitination of MDA5.","evidence":"Co-IP, ubiquitination assays, IFN reporter assays in SARS-CoV-2 infection","pmids":["37956198"],"confidence":"Medium","gaps":["Relationship between TRIM4 and TRIM65 ubiquitination of MDA5 not reconciled","Single-lab study"]},{"year":2024,"claim":"Resolved the cooperative biochemistry of filament turnover and LGP2's mechanistic role, showing adjacent subunits hydrolyze ATP cooperatively to disassemble filaments while LGP2 nucleates shorter filaments noncooperatively.","evidence":"Electron microscopy, ATPase and nucleotide-specificity assays, filament assembly, molecular modeling","pmids":["38309507"],"confidence":"High","gaps":["How cooperative disassembly tunes ligand selectivity quantitatively not defined","In-cell relevance of LGP2-shortened filaments untested"]},{"year":2024,"claim":"Identified MDA5 as the dedicated sensor of HIV-1 intron-containing RNA, requiring filament formation, dephosphorylation and MAVS association, with RIG-I dispensable.","evidence":"shRNA screen, nontargetable rescue, dominant-negative mutants, V-protein inhibitor, f-CLIP RNA-IP in primary dendritic cells","pmids":["38985764"],"confidence":"High","gaps":["Structural features of HIV-1 RNA recognized by MDA5 not defined","Role in HIV pathogenesis in vivo unknown"]},{"year":2024,"claim":"Defined the MDA5 degradation arm of negative regulation, showing RNF144B drives K27/K33-ubiquitination of MDA5 CARDs at Lys23/43 for p62-mediated autophagic destruction.","evidence":"Co-IP, ubiquitination mapping, Rnf144b-/- mice with EMCV challenge, p62 autophagy assays","pmids":["39285245"],"confidence":"High","gaps":["Trigger that activates RNF144B toward MDA5 unknown","Interplay with activating TRIM65 ubiquitination not resolved"]},{"year":2025,"claim":"Characterized the endogenous immunogenic dsRNA repertoire, showing it is a small mRNA-enriched, intron-depleted subset whose immunogenicity is dampened by ADAR1 editing.","evidence":"Transcriptomic 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Perspective.","date":"2021","source":"Viruses","url":"https://pubmed.ncbi.nlm.nih.gov/34834938","citation_count":10,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50361,"output_tokens":6944,"usd":0.127621,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16101,"output_tokens":6684,"usd":0.123802,"stage2_stop_reason":"end_turn"},"total_usd":0.251423,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"MDA5 (IFIH1) recognizes long poly(I:C) dsRNA and is specifically required for innate immune detection of picornaviruses, while RIG-I detects in vitro-transcribed short dsRNAs and other RNA viruses; MDA5-/- mice are highly susceptible to picornavirus infection, establishing distinct and non-redundant roles for each helicase.\",\n      \"method\": \"MDA5 knockout mice, in vivo viral challenge, type I IFN production assays\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout mice with defined viral-challenge phenotype, independently confirmed in multiple follow-up studies across labs\",\n      \"pmids\": [\"16625202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"IPS-1/MAVS is an essential downstream adaptor for both RIG-I and MDA5 antiviral signaling; MDA5 is individually dispensable for innate immune signaling triggered by reovirus and dengue virus in cultured fibroblasts, but RIG-I is essential for influenza A, influenza B, and RSV.\",\n      \"method\": \"siRNA knockdown of RIG-I, MDA5, and IPS-1 in cultured fibroblasts; IRF3 activation and ISG expression assays\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (siRNA, functional genomics, IRF3 activation), replicated across multiple virus systems\",\n      \"pmids\": [\"17942531\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MDA5 protein is degraded in poliovirus-infected cells via a proteasome- and caspase-dependent mechanism (not by viral proteinases 2Apro or 3Cpro), correlating with apoptosis induction; this degradation is proposed as a viral strategy to antagonize type I IFN production.\",\n      \"method\": \"Western blot, proteasome inhibitors, caspase inhibitors, proteinase-mutant viruses, puromycin-induced apoptosis controls\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple inhibitor approaches in single lab establishing mechanism of degradation\",\n      \"pmids\": [\"17267501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ADAR1-mediated A-to-I editing of endogenous dsRNA stem-loop structures in 3' UTRs of cellular transcripts is required to prevent MDA5 from sensing endogenous dsRNA as nonself; concurrent deletion of MDA5 rescues the embryonic lethality of editing-deficient Adar1(E861A/E861A) mice.\",\n      \"method\": \"Editing-deficient knock-in mice (Adar1 E861A), MDA5 double-knockout rescue, genome-wide RNA editing substrate identification\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — genetic epistasis with double-knockout rescue, genome-wide substrate mapping, replicated in subsequent independent studies\",\n      \"pmids\": [\"26275108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TRIM65 specifically interacts with MDA5 and catalyzes K63-linked ubiquitination of MDA5 at lysine 743, which is required for MDA5 oligomerization and activation; Trim65-/- mice cannot produce type I IFN and are more susceptible to EMCV infection.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, Trim65-/- knockout mice, EMCV challenge, IRF3 activation assays\",\n      \"journal\": \"The Journal of experimental medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, site-specific ubiquitination mapping, in vivo knockout phenotype with clean viral challenge\",\n      \"pmids\": [\"28031478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Constitutive activation of MDA5 in Aicardi-Goutières syndrome results from loss of tolerance to Alu retroelement-derived dsRNAs; AGS-associated MDA5 variants display reduced sensitivity to duplex structural irregularities and can form signaling-competent filaments on imperfect Alu-dsRNAs, whereas wild-type MDA5 cannot efficiently recognize them.\",\n      \"method\": \"RNase-protection/RNA-seq approach to identify endogenous MDA5 ligands; functional analysis of AGS variants; MDA5 filament assembly assays on Alu-dsRNAs\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (RNA-seq, biochemical filament assays, functional variant analysis) in single rigorous study\",\n      \"pmids\": [\"29395326\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"An IFIH1 gain-of-function missense mutation (p.Arg822Gln) causes Singleton-Merten syndrome by enhancing MDA5 function in IFN-β induction; in vitro functional analysis confirmed enhanced MDA5-mediated interferon signaling; interferon signature genes were upregulated in SMS patient blood and dental cells.\",\n      \"method\": \"Whole-exome sequencing, in vitro IFN-β induction assays with mutant IFIH1, immunohistochemistry, interferon signature gene expression\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro functional assay confirming gain-of-function, supported by patient gene expression data; single lab\",\n      \"pmids\": [\"25620204\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PACT (dsRNA-binding protein) functions as an essential coactivator of MDA5 by promoting dsRNA-induced oligomerization of MDA5; PACT-knockout cells show severely impaired virus- and poly(I:C)-induced MDA5-dependent type I IFN responses; PACT had no influence on MDA5-mediated NF-κB activation and required dsRNA interaction for its action.\",\n      \"method\": \"PACT knockout and knockdown cells, overexpression, oligomerization assays, IRF3-dependent IFN assays, colocalization studies\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockout and overexpression with multiple functional readouts, single lab\",\n      \"pmids\": [\"28760879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LGP2 facilitates MDA5 filament assembly by acting as a nucleator; LGP2 is incorporated into MDA5-dsRNA filaments (average inter-molecular distance ~32 nm), induces conformational changes in MDA5 promoting CARD domain exposure, and promotes conversion of MDA5 to an active conformation capable of downstream signaling even after filament dissociation by ATP hydrolysis.\",\n      \"method\": \"Biochemical filament assembly assays, biophysical approaches, limited protease digestion, ATP hydrolysis assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple biophysical and biochemical methods in single lab; no independent replication cited\",\n      \"pmids\": [\"33137199\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The disease-associated MDA5 variant M854K lacks ATPase activity, binds more stably to Alu:Alu dsRNA, and constitutively activates interferon signaling in the absence of exogenous RNA; cryo-EM structures of MDA5-dsRNA filaments reveal that K854 forms polar bonds constraining subdomain conformation and disrupting key steps in the ATPase cycle (RNA footprint expansion and helical twist modulation), inhibiting ATP-dependent RNA proofreading via an allosteric mechanism.\",\n      \"method\": \"CryoEM structural determination, ATPase activity assays, dsRNA binding assays, interferon signaling reporter assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cryo-EM structure with functional mutagenesis and biochemical validation in single rigorous study\",\n      \"pmids\": [\"34795277\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Adjacent MDA5 subunits in MDA5-dsRNA filaments hydrolyze ATP cooperatively, inducing cooperative filament disassembly; consecutive rounds of ATP hydrolysis amplify the filament footprint; LGP2 binds dsRNA at internal sites via noncooperative ATP hydrolysis, has low nucleic acid selectivity (can hydrolyze GTP and CTP as well as ATP), promotes MDA5 filament nucleation yielding shorter filaments, and makes key contacts with MDA5 via its C-terminal tail.\",\n      \"method\": \"Electron microscopy, biochemical ATPase assays, nucleotide specificity assays, filament assembly assays, molecular modeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — EM structural data combined with multiple orthogonal biochemical assays in single rigorous study\",\n      \"pmids\": [\"38309507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Enterovirus 71 RNA-dependent RNA polymerase (3Dpol) interacts specifically with the CARD domains of MDA5 and inhibits MDA5-mediated IFN-β promoter activation; coxsackievirus B3 3Dpol also interacts with MDA5 and downregulates MDA5-initiated antiviral signaling.\",\n      \"method\": \"Co-immunoprecipitation, reporter assays for IFN-β promoter activation, pulldown assays\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP and functional reporter assays, two viruses tested, single lab\",\n      \"pmids\": [\"30814289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EMCV non-structural protein 2C interacts with MDA5 to inhibit IFN-β signaling; mutation of amino acid V26 of 2C abolishes both IFN-β inhibition and MDA5 interaction; rescued viruses with 2C mutations induce significantly higher IFN-β levels.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis, reverse genetics (rescued virus), IFN-β reporter and mRNA assays\",\n      \"journal\": \"Antiviral research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis combined with reverse genetics and functional assays, single lab\",\n      \"pmids\": [\"30312637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MDA5 2CARD self-associates into large oligomers in a concentration-dependent manner in the absence of polyubiquitin, whereas RIG-I 2CARD requires unanchored K63-linked polyubiquitin for tetramerization; polyubiquitin (Ub4) binds MDA5 2CARD only weakly (1:1 and 2:1 stoichiometries) and does not induce 2CARD oligomerization, indicating distinct assembly mechanisms for RIG-I and MDA5 signaling.\",\n      \"method\": \"Sedimentation velocity analytical ultracentrifugation, multi-signal sedimentation velocity analysis\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — rigorous biophysical method (AUC), single lab, no independent replication\",\n      \"pmids\": [\"31697400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MDA5 is required for type I and type III IFN induction in lung epithelial cells (Calu-3) upon SARS-CoV-2 infection; this IFN induction further requires MAVS and IRF3; induction of IL-6 and TNF by SARS-CoV-2 is independent of the MDA5-MAVS-IRF3 axis.\",\n      \"method\": \"siRNA knockdown of MDA5, MAVS, IRF3; IFN and cytokine production assays in SARS-CoV-2-infected Calu-3 cells\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with multiple pathway components tested, replicated with multiple target knockdowns in single study\",\n      \"pmids\": [\"34211037\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"SARS-CoV-2 2'-O-methyltransferase Nsp16 shields viral RNA from MDA5-mediated recognition; recombinant SARS-CoV-2 with catalytically inactive Nsp16 (Nsp16mut) is highly immunogenic with strongly enhanced type I IFN release, and this elevated immunogenicity is absent in MDA5-deficient cells.\",\n      \"method\": \"Recombinant virus with Nsp16 catalytic mutant, MDA5 knockout cells, IFN production assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — recombinant virus combined with genetic knockout, single lab\",\n      \"pmids\": [\"36285486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SARS-CoV-2 nonstructural protein Nsp8 binds to both MDA5 and TRIM4, impairing TRIM4-mediated K63-linked polyubiquitination of MDA5, thereby suppressing MDA5 activation and downstream IRF3/NF-κB signaling and IFN production.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, IFN reporter assays, SARS-CoV-2 infection studies\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP with functional ubiquitination assays and IFN readouts; single lab\",\n      \"pmids\": [\"37956198\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ZFYVE1 specifically interacts with MDA5 (not RIG-I), binds viral RNA, and decreases MDA5 ligand binding and oligomerization, functioning as a specific negative regulator of MDA5-mediated (but not RIG-I-mediated) innate antiviral responses; Zfyve1-/- mice are protected from EMCV (MDA5-sensed) but not VSV (RIG-I-sensed) lethality.\",\n      \"method\": \"Co-immunoprecipitation, Zfyve1-/- knockout mice, viral challenge (EMCV and VSV), MDA5 oligomerization and ligand-binding assays\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, in vivo knockout with two virus challenge systems, biochemical oligomerization assays\",\n      \"pmids\": [\"32251420\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"IFIH1 (MDA5) is the innate immune receptor required for detection of intron-containing RNA from the HIV-1 provirus in primary human dendritic cells; MDA5 filament formation, dephosphorylation, and association with MAVS are all required for innate immune activation; MDA5 specifically enriches unspliced HIV-1 RNA over two orders of magnitude as shown by formaldehyde cross-linking immunoprecipitation (f-CLIP); DDX58/RIG-I knockdown had no effect.\",\n      \"method\": \"shRNA loss-of-function screen, nontargetable IFIH1 rescue, Nipah virus V protein inhibitor, dominant-negative IFIH1 mutants, f-CLIP RNA immunoprecipitation, RNA-Seq\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (shRNA screen, rescue, dominant-negative mutants, specific inhibitor, f-CLIP), single rigorous study\",\n      \"pmids\": [\"38985764\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss of ADAR1p150 activates both MDA5 and PKR; deleting both MDA5 and PKR completely rescues the embryonic lethality of Adar1p150-/- mice to adulthood, whereas removing MDA5 or PKR alone provides only limited or no rescue; loss of ADAR1-mediated RNA editing specifically activates MDA5, whereas loss of cytoplasmic ADAR1p150 or its dsRNA-binding activity enables PKR activation.\",\n      \"method\": \"Adar1p150-/- knockout mice, MDA5/PKR double-knockout epistasis, rescue experiments, survival analysis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — rigorous genetic epistasis with double-knockout rescue, clearly delineating MDA5 vs PKR roles downstream of ADAR1\",\n      \"pmids\": [\"37797622\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Transposable element transcripts (ERV and LINE superfamily copies) generated during chemotherapy-induced chromatin reorganization bind to and activate MDA5 in haematopoietic stem cells (HSCs), generating an inflammatory response required for HSC exit from quiescence; Mda5-/- HSCs retain quiescence and show better long-term repopulation after chemotherapy.\",\n      \"method\": \"Mda5-/- knockout mice, chemotherapy challenge, chromatin reorganization analysis, TE transcript overexpression/knockdown, HSC quiescence and repopulation assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean knockout mice with defined cellular phenotype, supported by TE overexpression/knockdown experiments\",\n      \"pmids\": [\"34253898\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"RNF144B specifically interacts with MDA5 CARDs and promotes K27/K33-linked polyubiquitination of MDA5 at lysine 23 and 43, which promotes autophagic degradation of MDA5 via p62; Rnf144b-/- mice show greatly enhanced IFN production and significantly higher survival upon EMCV infection.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination mapping, Rnf144b-/- knockout mice, EMCV challenge, p62-mediated autophagy assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — site-specific ubiquitination, in vivo knockout with viral challenge, mechanistic autophagy pathway validation\",\n      \"pmids\": [\"39285245\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Flavivirus prM protein from TBEV interacts with both MDA5 and MAVS, interfering with MDA5-MAVS complex formation and thereby impeding IRF3 nuclear translocation/dimerization and inhibiting RLR antiviral signaling; ZIKV and WNV prM similarly interact with both MDA5 and MAVS.\",\n      \"method\": \"Co-immunoprecipitation, IRF3 localization assays, IFN-I reporter assays, viral replication assays\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-IP with functional IFN reporter readout, single lab, multiple flaviviruses tested\",\n      \"pmids\": [\"36639652\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Transgenic mice expressing human MDA5 R779H mutant spontaneously develop myocarditis and nephritis with upregulated type I IFNs; cardiomyocyte-specific expression of hMDA5 R779H causes cardiomegaly and inflammatory cytokine upregulation; the phenotype requires intact MDA5-MAVS signaling and IFNAR (R779H Tg Mavs-/- and R779H Tg Ifnar-/- mice show no phenotype).\",\n      \"method\": \"Transgenic mice (whole-body and cardiomyocyte-specific), MAVS-/- and IFNAR-/- double knockouts, bone marrow transplantation, histopathology\",\n      \"journal\": \"Journal of autoimmunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific transgenic expression combined with MAVS/IFNAR double-knockout epistasis\",\n      \"pmids\": [\"35168003\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"IFIH1 promotes IRF3 nuclear translocation in macrophages via a MyD88-dependent mechanism when stimulated by LPS, in addition to its known RNA-sensing role; IFIH1 knockdown abolishes LPS-induced IRF3 activation and M1 polarization in RAW264.7 and BMDM cells.\",\n      \"method\": \"shRNA knockdown, IFIH1 overexpression lentiviral constructs, macrophage polarization assays, IRF3 activation measurements, GSEA\",\n      \"journal\": \"Frontiers in immunology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single primary cell type, limited mechanistic follow-up on the LPS/MyD88-IFIH1-IRF3 axis\",\n      \"pmids\": [\"33519803\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Immunogenic dsRNAs that activate MDA5 constitute a small fraction of all cellular dsRNAs, are highly enriched in mRNAs and depleted of introns (consistent with cytosolic localization), and their MDA5-dependent immunogenicity is dampened by ADAR1-mediated RNA editing.\",\n      \"method\": \"Transcriptomic/RNA-seq identification of immunogenic dsRNAs, MDA5-dependent immunogenicity validation, ADAR1 editing correlation analysis\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genome-wide identification with MDA5-dependent functional validation, single study\",\n      \"pmids\": [\"41339703\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Overexpression of Ifih1 (MDA5) in transgenic mice leads to a chronic type I IFN state with viral resistance; spontaneous MDA5 activation alone is not sufficient to initiate autoimmune or inflammatory pathology, but accelerates autoantibody production, glomerulonephritis, and early lethality on an FcγR2B-deficient lupus-susceptible background.\",\n      \"method\": \"Ifih1 multi-copy transgenic mice, viral challenge, autoimmune phenotyping, FcγR2B-deficient cross\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transgenic overexpression with defined phenotypic readouts and genetic crosses, single lab\",\n      \"pmids\": [\"22205024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"IFIH1 gain-of-function mutations cluster near the ATP-binding region of MDA5 and are associated with either increased RNA-binding affinity or decreased ATP hydrolysis efficiency and filament disassembly rate, establishing a common mutational mechanism for type I interferonopathies.\",\n      \"method\": \"Cohort genetic analysis with in vitro functional characterization of 27 mutations; ATP hydrolysis and RNA-binding assays\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional in vitro assays on multiple variants combined with large cohort genetic data\",\n      \"pmids\": [\"31898846\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MDA5 (IFIH1) is a cytoplasmic dsRNA sensor that forms cooperative helical filaments on long dsRNA substrates (preferentially viral dsRNA, including from picornaviruses, SARS-CoV-2, and HIV-1 intron-containing RNA), activating type I interferon signaling via its tandem CARD domains through MAVS; its ATPase activity fulfills an essential RNA-proofreading function that promotes dissociation from shorter endogenous dsRNAs while retaining longer viral dsRNAs, and this selectivity is disrupted by disease-associated gain-of-function mutations that allow recognition of endogenous Alu-element dsRNAs; activation requires TRIM65-mediated K63-linked ubiquitination at Lys743 for oligomerization, is enhanced by co-activators PACT and LGP2 (which acts as a nucleator promoting CARD exposure), and is negatively regulated by ZFYVE1 (inhibiting ligand binding/oligomerization) and RNF144B (promoting K27/K33-ubiquitination and autophagic degradation); ADAR1-mediated A-to-I editing of endogenous dsRNAs is the primary mechanism preventing MDA5 from triggering fatal autoinflammation in normal cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"IFIH1 (MDA5) is a cytoplasmic sensor of long double-stranded RNA that initiates type I and type III interferon responses, providing non-redundant antiviral immunity against picornaviruses and a range of other pathogens [#0, #1, #14]. Upon engaging long dsRNA, MDA5 assembles cooperative helical filaments along the RNA, a process that exposes its tandem N-terminal CARD domains to nucleate signaling through the mitochondrial adaptor MAVS and drive IRF3 activation [#5, #18, #23]. Filament-based activation is gated by an ATP-dependent RNA-proofreading function: adjacent subunits hydrolyze ATP cooperatively to disassemble filaments on shorter or imperfect duplexes while retaining longer bona fide viral dsRNA, conferring ligand selectivity [#9, #10]. Productive signaling additionally requires TRIM65-catalyzed K63-linked ubiquitination of MDA5 at Lys743 for oligomerization, and is augmented by the co-activator PACT and by LGP2, which nucleates MDA5 filament assembly and promotes the active CARD-exposed conformation [#4, #7, #8]. MDA5 activity is restrained by ZFYVE1, which suppresses ligand binding and oligomerization, and by RNF144B, which directs K27/K33-linked ubiquitination and p62-dependent autophagic degradation [#17, #21]. Tolerance to self is enforced by ADAR1-mediated A-to-I editing of endogenous dsRNAs, principally Alu-element and mRNA-derived stem-loops; loss of editing or gain-of-function MDA5 variants that recognize imperfect endogenous duplexes drive constitutive interferon production [#3, #5, #19, #25]. Such variants cause type I interferonopathies including Aicardi-Goutières syndrome and Singleton-Merten syndrome, with mutations clustering near the ATP-binding region to increase RNA affinity or impair ATP-dependent disassembly [#5, #6, #9, #27]. Diverse viral proteins antagonize this pathway by targeting MDA5 directly or its activating ubiquitination, and MDA5 also senses endogenous transposable-element transcripts to regulate hematopoietic stem cell quiescence [#11, #16, #20].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Established MDA5 as a distinct, non-redundant innate sensor by showing it is specifically required to detect picornaviruses, separating its function from RIG-I.\",\n      \"evidence\": \"MDA5 knockout mice with in vivo viral challenge and type I IFN assays\",\n      \"pmids\": [\"16625202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the molecular ligand features distinguishing MDA5 from RIG-I substrates\", \"Downstream adaptor not yet identified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Placed MDA5 in a defined signaling pathway by identifying MAVS/IPS-1 as the shared essential downstream adaptor and mapping virus-specific sensor usage.\",\n      \"evidence\": \"siRNA knockdown of RIG-I, MDA5, IPS-1 in fibroblasts with IRF3/ISG readouts\",\n      \"pmids\": [\"17942531\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of MDA5-MAVS coupling not resolved\", \"Cell-type dependence of sensor requirements unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Showed that picornaviruses actively antagonize MDA5 through proteasome- and caspase-dependent degradation, framing the sensor as a target of viral immune evasion.\",\n      \"evidence\": \"Western blot with proteasome/caspase inhibitors and proteinase-mutant viruses in poliovirus-infected cells\",\n      \"pmids\": [\"17267501\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of the responsible E3 ligase/protease not determined\", \"Single-lab mechanistic inference\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined the self/nonself discrimination problem by showing ADAR1 editing of endogenous dsRNA prevents MDA5 from sensing self, with MDA5 deletion rescuing editing-deficient lethality.\",\n      \"evidence\": \"Adar1 E861A editing-deficient knock-in mice with MDA5 double-knockout rescue and genome-wide substrate mapping\",\n      \"pmids\": [\"26275108\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish which specific endogenous RNAs trigger MDA5\", \"PKR contribution not yet separated\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified the activating post-translational switch by demonstrating TRIM65-mediated K63 ubiquitination at Lys743 is required for MDA5 oligomerization and antiviral function.\",\n      \"evidence\": \"Reciprocal Co-IP, site-specific ubiquitination mapping, Trim65-/- mice with EMCV challenge\",\n      \"pmids\": [\"28031478\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ubiquitination couples to filament/CARD assembly not structurally resolved\", \"Regulation of TRIM65 recruitment unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected MDA5 gain-of-function directly to human disease, showing the p.Arg822Gln variant enhances IFN-beta induction and causes Singleton-Merten syndrome.\",\n      \"evidence\": \"Whole-exome sequencing, in vitro IFN-beta induction assays, patient interferon signature analysis\",\n      \"pmids\": [\"25620204\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of enhanced signaling not defined\", \"Tissue specificity of pathology unexplained\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Elucidated the activation mechanism of CARD signaling, showing MDA5 2CARD self-oligomerizes concentration-dependently without polyubiquitin, unlike RIG-I.\",\n      \"evidence\": \"Sedimentation velocity analytical ultracentrifugation of 2CARD with/without Ub4\",\n      \"pmids\": [\"31697400\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation with TRIM65 ubiquitin requirement in cells not addressed\", \"Single-lab biophysical study\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified the endogenous immunogenic ligand class by showing Alu retroelement dsRNAs activate MDA5 in AGS and that disease variants form filaments on imperfect duplexes wild-type MDA5 cannot.\",\n      \"evidence\": \"RNase-protection/RNA-seq ligand identification, AGS variant functional analysis, filament assembly assays\",\n      \"pmids\": [\"29395326\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative threshold of duplex imperfection tolerated not defined\", \"Relationship to ATPase proofreading not yet structurally linked\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Extended the viral antagonism map by showing EMCV 2C binds MDA5 to suppress IFN-beta, validated by reverse genetics with a single residue determinant.\",\n      \"evidence\": \"Co-IP, V26 site-directed mutagenesis, rescued-virus reverse genetics, IFN-beta assays\",\n      \"pmids\": [\"30312637\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Step in MDA5 activation blocked by 2C not pinpointed\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified the CARD domain as a viral target by showing picornaviral 3Dpol polymerases bind MDA5 CARDs to inhibit IFN-beta induction.\",\n      \"evidence\": \"Co-IP, pulldown, IFN-beta promoter reporter assays for EV71 and CVB3\",\n      \"pmids\": [\"30814289\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether 3Dpol blocks oligomerization or MAVS coupling unclear\", \"No in vivo validation\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined LGP2 as a positive regulator acting as a filament nucleator that drives MDA5 into an active CARD-exposed conformation.\",\n      \"evidence\": \"Biochemical filament assembly, limited proteolysis, ATP hydrolysis assays\",\n      \"pmids\": [\"33137199\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo significance of nucleation not established\", \"Single-lab biochemical study\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified ZFYVE1 as a sensor-specific negative regulator restraining MDA5 ligand binding and oligomerization in vivo.\",\n      \"evidence\": \"Reciprocal Co-IP, Zfyve1-/- mice with EMCV and VSV challenge, oligomerization/ligand-binding assays\",\n      \"pmids\": [\"32251420\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of ZFYVE1-MDA5 inhibition not resolved\", \"Regulation of ZFYVE1 itself unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established a unifying mutational mechanism for interferonopathies by showing IFIH1 GOF variants cluster near the ATP-binding region and either raise RNA affinity or slow ATP hydrolysis/filament disassembly.\",\n      \"evidence\": \"Cohort genetics with in vitro ATP hydrolysis and RNA-binding assays on 27 variants\",\n      \"pmids\": [\"31898846\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not provide structural mechanism for individual variants\", \"Genotype-phenotype severity correlation incomplete\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Provided the structural mechanism of ATP-dependent proofreading, showing the M854K variant disrupts the ATPase cycle allosterically to stabilize binding on Alu:Alu dsRNA and constitutively signal.\",\n      \"evidence\": \"Cryo-EM of MDA5-dsRNA filaments, ATPase and dsRNA-binding assays, IFN reporter assays\",\n      \"pmids\": [\"34795277\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generality of the allosteric mechanism across all GOF variants not tested\", \"Dynamics of filament turnover in cells not captured\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended MDA5's antiviral role to SARS-CoV-2, establishing it as the sensor driving type I/III IFN via MAVS-IRF3 in lung epithelium.\",\n      \"evidence\": \"siRNA knockdown of MDA5/MAVS/IRF3 in infected Calu-3 cells with IFN/cytokine assays\",\n      \"pmids\": [\"34211037\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Identity of activating SARS-CoV-2 RNA species not defined here\", \"Knockdown rather than knockout system\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed a physiological role beyond infection, showing MDA5 senses chemotherapy-induced transposable-element transcripts to drive HSC exit from quiescence.\",\n      \"evidence\": \"Mda5-/- mice, chemotherapy challenge, TE transcript manipulation, HSC quiescence/repopulation assays\",\n      \"pmids\": [\"34253898\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking TE sensing to quiescence exit incompletely defined\", \"Whether other stresses engage the same axis unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated in vivo causality of an MDA5 GOF variant for organ-specific autoimmunity, with phenotype strictly dependent on MAVS and IFNAR.\",\n      \"evidence\": \"Whole-body and cardiomyocyte-specific hMDA5 R779H transgenic mice with MAVS-/- and IFNAR-/- crosses\",\n      \"pmids\": [\"35168003\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous RNA ligand driving the in vivo phenotype not identified\", \"Basis of tissue-specific susceptibility unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Expanded viral evasion strategies, showing flavivirus prM proteins disrupt MDA5-MAVS complex formation and that SARS-CoV-2 Nsp16 methylation shields viral RNA from MDA5.\",\n      \"evidence\": \"Co-IP and IRF3 localization assays (prM); recombinant Nsp16-mutant virus in MDA5-KO cells\",\n      \"pmids\": [\"36639652\", \"36285486\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural detail of complex disruption not resolved\", \"Single-lab studies\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Separated the ADAR1 effector pathways, showing loss of editing specifically activates MDA5 whereas loss of cytoplasmic ADAR1p150 dsRNA-binding activates PKR.\",\n      \"evidence\": \"Adar1p150-/- mice with MDA5/PKR double-knockout epistasis and survival analysis\",\n      \"pmids\": [\"37797622\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MDA5 and PKR sense overlapping or distinct RNA pools unresolved\", \"Crosstalk between the two effectors not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified a SARS-CoV-2 evasion mechanism converging on MDA5 ubiquitination, showing Nsp8 sequesters TRIM4 to block K63-ubiquitination of MDA5.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, IFN reporter assays in SARS-CoV-2 infection\",\n      \"pmids\": [\"37956198\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relationship between TRIM4 and TRIM65 ubiquitination of MDA5 not reconciled\", \"Single-lab study\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved the cooperative biochemistry of filament turnover and LGP2's mechanistic role, showing adjacent subunits hydrolyze ATP cooperatively to disassemble filaments while LGP2 nucleates shorter filaments noncooperatively.\",\n      \"evidence\": \"Electron microscopy, ATPase and nucleotide-specificity assays, filament assembly, molecular modeling\",\n      \"pmids\": [\"38309507\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How cooperative disassembly tunes ligand selectivity quantitatively not defined\", \"In-cell relevance of LGP2-shortened filaments untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified MDA5 as the dedicated sensor of HIV-1 intron-containing RNA, requiring filament formation, dephosphorylation and MAVS association, with RIG-I dispensable.\",\n      \"evidence\": \"shRNA screen, nontargetable rescue, dominant-negative mutants, V-protein inhibitor, f-CLIP RNA-IP in primary dendritic cells\",\n      \"pmids\": [\"38985764\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural features of HIV-1 RNA recognized by MDA5 not defined\", \"Role in HIV pathogenesis in vivo unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined the MDA5 degradation arm of negative regulation, showing RNF144B drives K27/K33-ubiquitination of MDA5 CARDs at Lys23/43 for p62-mediated autophagic destruction.\",\n      \"evidence\": \"Co-IP, ubiquitination mapping, Rnf144b-/- mice with EMCV challenge, p62 autophagy assays\",\n      \"pmids\": [\"39285245\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trigger that activates RNF144B toward MDA5 unknown\", \"Interplay with activating TRIM65 ubiquitination not resolved\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Characterized the endogenous immunogenic dsRNA repertoire, showing it is a small mRNA-enriched, intron-depleted subset whose immunogenicity is dampened by ADAR1 editing.\",\n      \"evidence\": \"Transcriptomic identification with MDA5-dependent immunogenicity validation and ADAR1 editing correlation\",\n      \"pmids\": [\"41339703\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural determinants making these RNAs immunogenic not fully defined\", \"Single study\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How activating (TRIM65 K63) and degradative (RNF144B K27/K33) ubiquitination, LGP2/PACT co-activation, and ATP-dependent proofreading are integrated in real time to set the threshold distinguishing self from viral dsRNA remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No unified model coupling ubiquitin state to filament dynamics\", \"Spatiotemporal regulation of activating vs degradative modifications unknown\", \"Mechanism setting per-cell activation threshold undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003723\", \"supporting_discovery_ids\": [0, 5, 18, 25]},\n      {\"term_id\": \"GO:0140098\", \"supporting_discovery_ids\": [9, 10]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [9, 10, 27]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 18, 23]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 25]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 1, 14, 18]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [5, 6, 23, 27]}\n    ],\n    \"complexes\": [\n      \"MDA5-dsRNA filament\",\n      \"MDA5-MAVS signaling complex\"\n    ],\n    \"partners\": [\n      \"MAVS\",\n      \"TRIM65\",\n      \"LGP2\",\n      \"PACT\",\n      \"ZFYVE1\",\n      \"RNF144B\",\n      \"ADAR1\",\n      \"TRIM4\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}