{"gene":"TRIM21","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2016,"finding":"TRIM21 directly interacts with SQSTM1/p62 and ubiquitylates p62 at lysine 7 (K7) via K63-linked ubiquitin chains, which abrogates p62 oligomerization and sequestration of client proteins (including Keap1), thereby suppressing the antioxidant response. TRIM21-deficient cells display enhanced antioxidant response and reduced cell death under oxidative stress.","method":"Co-IP, ubiquitination assay, mutagenesis (K7 site), genetic ablation in mice (liver insult and pressure overload models)","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — reciprocal Co-IP, site-specific mutagenesis, in vitro ubiquitination assay, and in vivo genetic ablation with defined phenotypic readout","pmids":["26942676"],"is_preprint":false},{"year":2017,"finding":"TRIM21 acts as a cytosolic Fc receptor that detects antibody-coated tau seeds entering the cell; after binding, TRIM21 neutralizes tau seeds through the proteasome and AAA ATPase p97/VCP, inhibiting pathological tau aggregate formation.","method":"Fluorescent morphology-based seeding assays, TRIM21 knockdown/overexpression, pharmacological inhibition of proteasome and p97/VCP","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (seeding assay, proteasome/p97 inhibitors, TRIM21 manipulation) in a single study; replicated in subsequent in vivo work (PMID 36996217)","pmids":["28049840","36996217"],"is_preprint":false},{"year":2019,"finding":"TRIM21 interacts with SAMHD1 and promotes its K48-linked ubiquitination and proteasomal degradation, thereby reducing SAMHD1-dependent restriction of EV71 and HIV-1 replication. The SPRY domain of TRIM21 is required for SAMHD1 binding and K622 of SAMHD1 is the ubiquitination site.","method":"Co-IP, in vitro ubiquitination assay, domain-deletion mutants, neonatal mouse model","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — Co-IP, ubiquitination assay, mutagenesis of binding/ubiquitination sites, in vivo mouse model; single lab with multiple orthogonal methods","pmids":["31797533"],"is_preprint":false},{"year":2018,"finding":"TRIM21 mediates antibody-dependent inhibition of adenoviral gene delivery in vivo; genetic KO of TRIM21 or a single antibody point mutation restores transgene expression. TRIM21 is also responsible for blocking cytotoxic T cell induction by adenoviral vaccine vectors and for upregulating hundreds of innate/intrinsic immune genes in vector-transduced tissue.","method":"TRIM21 genetic knockout mice, antibody point mutant, transcriptomic analysis of transduced tissue, viral challenge models","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with defined in vivo phenotype, antibody mutagenesis, transcriptomics; multiple orthogonal approaches in single study","pmids":["30209217"],"is_preprint":false},{"year":2020,"finding":"TRIM21 functions as an E3 ubiquitin ligase targeting G6PD for degradation, thereby negatively regulating the pentose phosphate pathway (PPP). PI3K/AKT activation inhibits TRIM21 to stabilize G6PD and promote PPP flux. Knockout of TRIM21 promotes PPP activity and cell proliferation.","method":"TRIM21 knockout/overexpression, ubiquitination assays, PTEN-null cancer cell models and murine in vivo models","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO and OE with functional readouts, in vivo models; single lab, mechanism partially inferred","pmids":["32312982"],"is_preprint":false},{"year":2020,"finding":"TRIM21 uses anti-nucleoprotein (N) antibodies to target viral N protein for cytosolic degradation and generate cytotoxic T cells against N peptide, providing T cell-mediated viral clearance via antibody-dependent intracellular neutralization (ADIN) in LCMV infection.","method":"TRIM21 KO mice, LCMV infection model, CTL assays, antibody transfer experiments","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO mice with viral challenge, multiple functional readouts (viral clearance, CTL induction); in vivo and in vitro orthogonal methods","pmids":["33258165"],"is_preprint":false},{"year":2021,"finding":"TRIM21 interacts with GSDMD via its PRY-SPRY domain, maintaining GSDMD stable expression in resting cells and inducing GSDMD-N terminus aggregation during pyroptosis, thereby acting as a positive regulator of GSDMD-dependent pyroptosis. TRIM21-deficient cells show reduced pyroptosis in response to NLRP3 or NLRC4 inflammasome activation, and TRIM21 KO mice are protected from LPS-induced inflammation and DSS-induced colitis.","method":"Co-IP (PRY-SPRY domain mapping), TRIM21 KO cells and mice, inflammasome activation assays, colitis model","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with domain mapping, KO cells with defined pyroptosis phenotype, in vivo mouse models; multiple orthogonal methods","pmids":["34511601"],"is_preprint":false},{"year":2023,"finding":"TRIM21 promotes K48-linked ubiquitination and proteasomal degradation of VDAC2, inhibiting VDAC2 oligomer pore formation and thereby blocking mitochondrial DNA release and cGAS/STING pathway activation following irradiation in nasopharyngeal carcinoma cells.","method":"TRIM21 KO, Co-IP, ubiquitination assay, mitochondrial DNA release assay, cGAS/STING pathway readouts, in vivo tumor models","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO with defined mechanistic pathway, reciprocal Co-IP, ubiquitination assay, multiple in vitro and in vivo readouts","pmids":["36797289"],"is_preprint":false},{"year":2023,"finding":"TRIM21 catalyzes K63-linked ubiquitination of the stress granule core protein G3BP1, which effectively inhibits G3BP1 liquid-liquid phase separation (LLPS) and stress granule formation in vitro and in cells.","method":"E3 ligase screen in SGs, Co-IP, in vitro LLPS assay, TRIM21 knockdown/overexpression, ubiquitination assay","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro LLPS reconstitution with ubiquitinated G3BP1, Co-IP, KD/OE cellular phenotype; single lab but multiple orthogonal methods","pmids":["36692217"],"is_preprint":false},{"year":2023,"finding":"UBE2M (E2 enzyme) neddylates TRIM21 at K129/K134; this neddylation promotes TRIM21-mediated K48-linked ubiquitination and degradation of VHL, which prevents VHL-dependent degradation of HIF-1α and sustains IL-1β production in macrophages during obesity-induced inflammation.","method":"UBE2M KO macrophage mice, neddylation assay, Co-IP, ubiquitination assay, HFD mouse models","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — neddylation site-specific mutagenesis (K129/134), Co-IP, ubiquitination assay, in vivo KO models; multiple orthogonal methods","pmids":["37343564"],"is_preprint":false},{"year":2022,"finding":"TRIM21 directly interacts with and ubiquitinates CLASPIN via K63-linked chains, which counteracts the K6-linked ubiquitination of CLASPIN essential for its interaction with TIPIN and chromatin loading. Overexpression of TRIM21 (but not a catalytically inactive mutant) compromises CHK1 activation, leading to replication fork instability.","method":"Co-IP, ubiquitination assay, catalytically inactive TRIM21 mutant, CHK1 activation assays, replication fork assays","journal":"Nucleic acids research","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — Co-IP, ubiquitination assay with linkage-specific analysis, catalytic mutant control, functional replication fork readout; single lab with multiple orthogonal methods","pmids":["35048968"],"is_preprint":false},{"year":2023,"finding":"TRIM21 identified as an E3 ubiquitin ligase for mutant p53 (mutp53); it directly interacts with mutp53 but not wild-type p53, promoting mutp53 ubiquitination and proteasomal degradation to suppress mutp53 gain-of-function in tumorigenesis. TRIM21 deletion in p53R172H knockin mice caused mutp53 accumulation in normal tissues and earlier tumor onset.","method":"mutp53-interacting protein screen, Co-IP, ubiquitination assay, TRIM21 KO in p53R172H knockin mice","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — protein screen, Co-IP, ubiquitination assay, in vivo genetic mouse model with defined tumor phenotype; multiple orthogonal methods","pmids":["36749630"],"is_preprint":false},{"year":2023,"finding":"TRIM21 mediates K63-linked ubiquitination of FSP1 at K322 and K366 residues, which is essential for FSP1 plasma membrane translocation and its ferroptosis suppression activity.","method":"Co-IP, ubiquitination assay with site-directed mutagenesis (K322R, K366R), membrane fractionation, RSL3-induced ferroptosis assays, subcutaneous tumor model","journal":"Advanced science","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — site-specific mutagenesis, ubiquitination assay, membrane fractionation to link modification to localization change; single lab with multiple orthogonal methods","pmids":["37587773"],"is_preprint":false},{"year":2023,"finding":"TRIM21 ubiquitylates GPX4, promoting its degradation, and thereby promotes ferroptosis in ischemia/reperfusion-induced acute kidney injury. TRIM21 KO mice are protected from I/R-AKI with upregulated GPX4.","method":"Co-IP, ubiquitination assay, Trim21-/- mice I/R model, H/R cell model, ferroptosis markers","journal":"Life sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO mouse model with defined phenotype; single lab","pmids":["36958437"],"is_preprint":false},{"year":2023,"finding":"TRIM21 directly interacts with SARS-CoV-2 nucleocapsid (N) protein and ubiquitinates it at K375, leading to proteasomal degradation. This ubiquitination was also observed for N proteins of SARS-CoV-2 variants and related coronaviruses.","method":"Immunoprecipitation/mass spectrometry, Co-IP, ubiquitination assay, proteasome inhibitor experiments","journal":"Journal of medical virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP-MS identification, Co-IP, site-mapped ubiquitination assay; single lab","pmids":["37185839"],"is_preprint":false},{"year":2020,"finding":"TRIM21 interacts with the TP domain of HBV DNA polymerase (Pol) via its SPRY domain and promotes ubiquitination at K260 and K283 of HBV Pol using its RING domain, leading to proteasomal degradation and restriction of HBV DNA replication.","method":"FLAG affinity purification/mass spectrometry, Co-IP, ubiquitination assay, domain deletion mutants, HBV replication assays","journal":"Viruses","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity purification/MS, Co-IP, site-specific ubiquitination mapping with mutagenesis, functional replication assay; single lab","pmids":["32245233"],"is_preprint":false},{"year":2022,"finding":"TRIM21 promotes K48-linked ubiquitination of IRF7, leading to its degradation, to promote rabies virus (RABV) replication via the IRF7-IFN axis; TRIM21 knockdown inhibits RABV replication while overexpression promotes it.","method":"TRIM21 knockdown/overexpression, Co-IP, ubiquitination assay, IFN production assays, RABV replication assays","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD/OE with functional viral replication readout, Co-IP, IRF7 degradation assay; single lab","pmids":["37446070"],"is_preprint":false},{"year":2022,"finding":"TRIM21 directly interacts with STAT1 and acts as its E3 ubiquitin ligase, promoting STAT1 ubiquitination and degradation. TGM2 (in a GTP-binding-dependent manner) facilitates dissociation of TRIM21 from STAT1, thereby stabilizing STAT1 and promoting gastric cancer progression.","method":"Co-IP, mass spectrometry, ubiquitination assay, TGM2 mutagenesis, TGM2-STAT1-TRIM21 interaction studies","journal":"Cancer communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, MS-identified interaction, ubiquitination assay, enzyme activity mutagenesis; single lab","pmids":["36353796"],"is_preprint":false},{"year":2022,"finding":"LPS challenge promotes the interaction between TRIM21 and SIRT5, leading to TRIM21-mediated SIRT5 ubiquitination and degradation. SIRT5 degradation sustains acetylation of TRIM21 at K351, increasing its E3 ligase activity in LPS-activated macrophages and enhancing IL-1β production.","method":"Co-IP, ubiquitination assay, deubiquitinase (HAUSP) competition assay, K351 acetylation mapping, IL-1β ELISA, DSS colitis model","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, acetylation site mutagenesis, in vivo colitis model; single lab with multiple orthogonal methods","pmids":["35770730"],"is_preprint":false},{"year":2023,"finding":"Mtb infection promotes TRIM21-mediated proteasomal degradation of HERC2 (an E3 ligase of NCOA4), via p38/AKT1 signaling, which stabilizes NCOA4 and enhances NCOA4-mediated ferritin degradation (ferritinophagy), increasing iron bioavailability for intracellular Mtb growth.","method":"Co-IP, ubiquitination assay, NCOA4 KO myeloid mice, HERC2 degradation assays, Mtb infection models","journal":"The Journal of clinical investigation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, genetic KO mice with bacterial clearance readout; single lab","pmids":["37066876"],"is_preprint":false},{"year":2023,"finding":"TRIM21 directly interacts with and ubiquitinates MST2 at K473 via K63-linked chains, enabling MST2 homodimer formation and enhanced MST2 kinase activity, ultimately inactivating YAP and inhibiting EMT in colorectal cancer.","method":"Co-IP, ubiquitination assay with site mutagenesis, MST2 kinase activity assay, YAP phosphorylation readout, mouse CRC models and organoids","journal":"Cell chemical biology","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — Co-IP, site-specific ubiquitination mutagenesis, kinase activity assay, in vivo tumor models; single lab with multiple orthogonal methods","pmids":["37354905"],"is_preprint":false},{"year":2023,"finding":"TRIM21 promotes K48-linked ubiquitination of METTL3 at K459, leading to its proteasomal degradation, thereby promoting ferroptosis by preventing SLC7A11 mRNA stabilization in pancreatic cancer.","method":"Co-IP, ubiquitination assay with site mutagenesis (K459), ferroptosis assays, in vivo pancreatic cancer models","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, site-specific ubiquitination, KO/OE with ferroptosis readout; single lab","pmids":["40175350"],"is_preprint":false},{"year":2023,"finding":"TRIM21 interacts with and ubiquitinates SQSTM1/p62 at K7 via K63 linkage, abolishing TBK1-mediated phosphorylation of p62 at S403 and preventing p62 aggregation. TRIM21 is oxidized at C92, C111, C114 to form disulfide bonds causing oligomerization and reduced E3 activity, which in turn allows S403 phosphorylation and p62-mediated antioxidant sequestration.","method":"Co-IP, ubiquitination assay, phosphorylation assay, Cys-to-Ser mutagenesis, in vitro dimerization assay, PA-treated MEF and mouse models","journal":"Autophagy","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple site-specific mutagenesis, in vitro biochemical assays, KO mouse models with defined phenotype; single lab with multiple orthogonal methods","pmids":["39172027"],"is_preprint":false},{"year":2023,"finding":"TRIM21 ubiquitinates ChREBP, SREBP1, ACC1, FASN, and A1CF (key lipogenesis and fructose metabolism regulators) via ubiquitin-mediated proteasomal degradation, limiting de novo lipogenesis in NASH. TRIM21 expression is induced by TNF-α plus fatty acids synergistically.","method":"Co-IP, ubiquitination assay, TRIM21 KO/OE in primary hepatocytes and mice, metabolic phenotyping","journal":"JCI insight","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, in vivo KO phenotype; single lab, multiple substrates identified","pmids":["37937648"],"is_preprint":false},{"year":2024,"finding":"TRIM21 directly interacts with c-Myc and ubiquitinates it at K148 via K63-linked chains, enabling c-Myc targeting to the autophagy machinery for degradation. ERK2 (downstream of mutant KRAS) phosphorylates TRIM21 at T396, disrupting the TRIM21-c-Myc interaction and preventing c-Myc autophagic degradation.","method":"Co-IP, ubiquitination assay (K63, K148 site mutagenesis), ERK2 phosphorylation assay (T396), autophagy flux assays, KRAS-mutant CRC models","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — multiple site-specific mutagenesis, Co-IP, phosphorylation assay, autophagy flux readout, in vivo models; single lab with multiple orthogonal methods","pmids":["39388269"],"is_preprint":false},{"year":2024,"finding":"(S)-ACE-OH acts as a molecular glue to induce TRIM21-NUP98 interaction, leading to ubiquitin-proteasome-dependent degradation of nuclear pore proteins and disruption of nucleocytoplasmic trafficking. TRIM21-based PROTACs enable selective degradation of multimeric/condensate proteins, consistent with a requirement for substrate clustering for TRIM21 activation.","method":"Co-IP, crystallography (TRIM21-NUP98 interface), proteomic studies, proteasome inhibitor experiments, TRIM21 KO validation","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystallographic structure of TRIM21-NUP98 interface, multiple molecular glue degraders validated, proteomic confirmation, KO controls","pmids":["39488207"],"is_preprint":false},{"year":2023,"finding":"TRIM21-dependent target protein ubiquitination (not TRIM21 self-ubiquitination) is required for Trim-Away degradation, as demonstrated in Xenopus egg cell-free extracts; chemical methylation of TRIM21 had no effect on target proteolysis, whereas deletion of all lysines in target protein abolished ubiquitination and proteasomal degradation.","method":"Cell-free Xenopus egg extract system, chemical methylation of TRIM21, target protein lysine-deletion mutagenesis, proteasomal degradation assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution, chemical mutagenesis, target protein mutagenesis; mechanistically definitive study challenging prior models","pmids":["36807144"],"is_preprint":false},{"year":2022,"finding":"TRIM21 promotes K63-linked ubiquitination of ISG12a and facilitates its translocation into mitochondria, causing caspase 3 activation; caspase 3 then cleaves GSDME specifically during viral infection, releasing GSDME N-terminal domain and causing pyroptosis.","method":"Co-IP, ubiquitination assay, mitochondrial fractionation, caspase 3 activation assay, GSDME cleavage assay, viral infection model","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, subcellular fractionation linked to functional pyroptosis readout; single lab","pmids":["36426955"],"is_preprint":false},{"year":2023,"finding":"TRIM21 interacts with EPHX1 through its SPRY domain and promotes K33- and K48-linked ubiquitination at K105 of EPHX1, leading to its degradation and inhibition of arachidonic acid metabolism in pancreatic cancer.","method":"Proteomics, ubiquitomics, LC-MS/MS, Co-IP, SPRY domain mapping, ubiquitination assay with site mutagenesis","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multi-omic approach, Co-IP, domain mapping, site-specific ubiquitination; single lab","pmids":["39739616"],"is_preprint":false},{"year":2023,"finding":"TRIM21 interacts with and promotes K48-linked ubiquitination-dependent degradation of NCL (nucleolin) at K239, suppressing HCC metastasis; circ0006646 prevents NCL-TRIM21 interaction to protect NCL from degradation.","method":"Co-IP, ubiquitination assay with site mutagenesis (K239), circ0006646 silencing, multi-omics, in vivo xenograft","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, site-specific ubiquitination assay, in vivo models; single lab","pmids":["38357830"],"is_preprint":false},{"year":2023,"finding":"TRIM21 restricts influenza A virus subtypes H3/H5/H9 (but not H1/H7) by binding to residue R95 of M1 matrix protein and facilitating K48-linked ubiquitination of M1 K242 for proteasomal degradation. Recombinant viruses with M1 R95K or K242R mutations were resistant to TRIM21.","method":"Co-IP, ubiquitination assay, site-directed mutagenesis (R95K, K242R), proteasomal degradation assays, recombinant virus rescue","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — Co-IP, site-specific mutagenesis validated by recombinant virus rescue, ubiquitination linkage mapping; single lab with multiple orthogonal methods","pmids":["37343022"],"is_preprint":false},{"year":2024,"finding":"TRIM21 promotes K63-linked ubiquitination of PD-1 at K233, stabilizing PD-1 by antagonizing its K48-linked ubiquitination and degradation. Trim21 KO significantly decreases PD-1 expression, enhances CD8+ T cell activation, and sensitizes tumors to anti-CTLA-4 immunotherapy.","method":"Co-IP, ubiquitination assay with linkage and site (K233) mutagenesis, Trim21 KO mice, CD8+ T cell activation assays, in vivo tumor models","journal":"Molecular therapy","confidence":"High","confidence_rationale":"Tier 2 / Moderate — site-specific ubiquitination mutagenesis, reciprocal Co-IP, KO mouse models with defined immunological phenotype; single lab with multiple orthogonal methods","pmids":["39905727"],"is_preprint":false},{"year":2024,"finding":"TRIM21 promotes K63-linked ubiquitination of TAT (tyrosine aminotransferase) at K136 via interaction involving H336/H338 of TRIM21; this ubiquitination impairs TAT dimerization and mitochondrial localization, inhibiting cardiolipin-dependent mitophagy and GBC liver metastasis.","method":"Co-IP with TRIM21 domain mutagenesis (H336/H338), ubiquitination assay (K63, K136), TAT dimerization assay, mitochondrial localization assay, in vivo metastasis model","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with binding site mutagenesis, ubiquitination assay, localization readout; single lab","pmids":["38697462"],"is_preprint":false},{"year":2024,"finding":"TRIM21 mediates K63-linked ubiquitination and lysosomal degradation of AXL receptor; STAMBPL1 (a deubiquitinase) antagonizes this to stabilize AXL, promoting EMT and immune evasion in kidney renal clear cell carcinoma.","method":"Co-IP, ubiquitination assay (K63 linkage), lysosomal inhibitor experiments, STAMBPL1 KD with rescue experiments","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination linkage assay, lysosomal pathway validation, deubiquitinase rescue; single lab","pmids":["39527690"],"is_preprint":false},{"year":2023,"finding":"EGFR activation induces c-Src-mediated phosphorylation of CD47 at Y288, which inhibits TRIM21-mediated K99/K102 polyubiquitylation and degradation of CD47, leading to CD47 accumulation and tumor immune evasion.","method":"Co-IP, ubiquitination assay with site mutagenesis (Y288F, K99/102R knock-in), macrophage phagocytosis assay, in vivo brain tumor model","journal":"Advanced science","confidence":"High","confidence_rationale":"Tier 2 / Strong — knock-in mutagenesis, Co-IP, ubiquitination assay, in vivo tumor model with immune readout; multiple orthogonal methods","pmids":["37541303"],"is_preprint":false},{"year":2025,"finding":"Small-molecule ligands to TRIM21 identified by DEL technology; crystallography confirmed ligand interaction with TRIM21. Treatment induced TRIM21-dependent, ubiquitin-proteasome-dependent degradation of NUP155 (primary target) and GLE1 (passenger), impairing nuclear envelope integrity.","method":"DNA-Encoded Library screen, crystallography, proteomic profiling, TRIM21 KO validation, proteasome inhibitor, immunofluorescence","journal":"ACS chemical biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure of TRIM21-ligand complex, proteomic validation, KO controls, mechanistic pathway defined; single lab with multiple orthogonal methods","pmids":["40247740"],"is_preprint":false},{"year":2024,"finding":"USP28 deubiquitinates and stabilizes TRIM21 in cardiomyocytes; stabilized TRIM21 negatively regulates Nrf2 antioxidant response, increasing oxidative stress and promoting cardiac hypertrophy. USP28 CKO protects against Ang II- and TAC-induced cardiac dysfunction.","method":"Co-IP/mass spectrometry (substrate screen), cardiomyocyte-specific USP28 KO mice, deubiquitination assay, Nrf2 pathway readout, cardiac hypertrophy models","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS, KO mouse model with defined cardiac phenotype, deubiquitination assay; single lab","pmids":["39431010"],"is_preprint":false},{"year":2022,"finding":"CDK2 phosphorylates PXR at Ser350, promoting PXR dissociation from Hsp90/DNAJC7 and subsequent TRIM21-mediated PXR ubiquitination and proteasomal degradation.","method":"Co-IP, ubiquitination assay, CDK2 kinase assay, PXR-S350 phosphorylation site mutagenesis, Hsp90/DNAJC7 interaction assay","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, phosphorylation site mutagenesis; single lab with multiple orthogonal methods","pmids":["35053380"],"is_preprint":false},{"year":2024,"finding":"TRIM21 interacts with ERK1/2 through its PRY-SPRY domain and catalyzes K27-linked ubiquitination of ERK1/2; this ubiquitination promotes ERK1/2-MEK1/2 interaction and subsequent ERK1/2 phosphorylation. Excess TRIM21 suppresses ERK1/2 phosphorylation by activating negative feedback pathways.","method":"CRISPR-Cas9 screen, Co-IP with domain mapping (PRY-SPRY), ubiquitination assay (K27 linkage), NanoBiT protein interaction assay, RNA-seq","journal":"Neuro-oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR screen, Co-IP with domain mapping, linkage-specific ubiquitination; single lab","pmids":["39533840"],"is_preprint":false},{"year":2024,"finding":"TRIM21 interacts with ACSL4 and promotes its ubiquitination and degradation; USP15 (deubiquitinase) counteracts this by deubiquitinating and stabilizing ACSL4. The balance between TRIM21 and USP15 determines ACSL4 levels and imatinib sensitivity in gastrointestinal stromal tumors.","method":"Co-IP, ubiquitination assay, deubiquitination assay, shRNA knockdown, xenograft mouse model","journal":"British journal of cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination/deubiquitination assays, in vivo xenograft; single lab","pmids":["38182686"],"is_preprint":false},{"year":2024,"finding":"TRIM21 interacts with and promotes K48-linked ubiquitination of CNOT4 at K239 (via K48 and K6 linkage) when complexed with TNKS1BP1, leading to CNOT4 degradation and downstream autophagy/lipid reprogramming effects in HCC.","method":"Co-IP, ubiquitination assay with site mutagenesis (K239), mass spectrometry, in vivo HCC models","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, MS, site-specific ubiquitination assay; single lab","pmids":["39019859"],"is_preprint":false},{"year":2024,"finding":"TRIM21 catalyzes K48-linked ubiquitination of TRPV2 at K295 in myeloid cells, promoting TRPV2 lysosomal/proteasomal degradation and reducing viral spread. TRPV2-K295R mutant is resistant to TRIM21-dependent degradation and promotes viral infection more profoundly than wild-type TRPV2.","method":"Co-IP, ubiquitination assay with site mutagenesis (K295R), Trim21-/- mice, TRPV2 KO reconstitution, viral infection assays (HSV-1, VSV)","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — site-specific mutagenesis with reconstitution, KO mice, multiple viral models; single lab with multiple orthogonal methods","pmids":["38613787"],"is_preprint":false},{"year":2024,"finding":"TRIM21 promotes K48-linked ubiquitination of SREBF1, leading to its proteasomal degradation and consequent downregulation of lipogenic enzyme expression (reducing lipid accumulation) in renal cell carcinoma.","method":"Co-IP, immunoprecipitation, ubiquitination assay, TRIM21 KO/OE, metabolomics, Oil Red O staining, in vivo orthotopic model","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO/OE with metabolic phenotype; single lab","pmids":["36694250"],"is_preprint":false},{"year":2024,"finding":"ANTIBODIES targeting CCHFV nucleoprotein (NP) protect against lethal CCHFV challenge through TRIM21-dependent mechanisms (intracellular Fc receptor function); TRIM21-deficient vaccinated mice cannot control infection despite robust CCHFV-specific immunity. Passive transfer of NP-immune sera confers TRIM21-dependent protection.","method":"TRIM21 KO mice, passive serum transfer, Fc-gamma receptor and complement KO controls, lethal challenge model","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with in vivo lethal challenge, passive transfer, multiple receptor-deficient controls establishing TRIM21 specificity","pmids":["39455551"],"is_preprint":false},{"year":2023,"finding":"TRIM21 promotes ubiquitination of Sohlh2 and its proteasomal degradation, suppressing M2 macrophage polarization and triple-negative breast cancer progression.","method":"Co-IP, ubiquitination assay, TRIM21 KO/OE in macrophages, M2 polarization assays, in vivo metastasis model","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO/OE with defined cellular phenotype; single lab","pmids":["38123542"],"is_preprint":false},{"year":2024,"finding":"TRIM21 promotes K63-linked ubiquitination and promotes nuclear translocation of PKM2 in astrocytes; nuclear PKM2 phosphorylates STAT3 and NF-κB and interacts with c-Myc, promoting astrocyte activation and glycolysis in experimental autoimmune encephalomyelitis.","method":"Co-IP, ubiquitination assay, TRIM21 OE/KD in primary astrocytes, nuclear PKM2 activity assays, intracerebroventricular lentiviral KD, EAE mouse model","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, in vivo KD with disease model readout; single lab","pmids":["39264698"],"is_preprint":false},{"year":2023,"finding":"TRIM21 mutually regulates TRIM8 via K48-linked ubiquitination: TRIM21 promotes proteasomal degradation of TRIM8, and TRIM8 reciprocally promotes degradation of TRIM21 via K48-linked ubiquitination.","method":"Co-IP, ubiquitination assay (K48 linkage), proteasome inhibitor experiments, expression correlation in NSCLC and RCC clinical samples","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, ubiquitination assay with linkage specificity; single lab","pmids":["37914816"],"is_preprint":false}],"current_model":"TRIM21 is a cytosolic RING-domain E3 ubiquitin ligase and high-affinity Fc receptor that intercepts antibody-coated pathogens entering the cytosol, targeting them for proteasomal destruction via K63-linked ubiquitination (requiring target protein polyubiquitination rather than TRIM21 self-ubiquitination), while simultaneously activating innate immune signaling; beyond its antiviral role, TRIM21 ubiquitinates a broad range of cellular substrates—including p62/SQSTM1 (K7, K63), IRF family members, GSDMD regulators, G3BP1 (K63), CLASPIN (K63), mutant p53, GPX4, FSP1 (K63), VDAC2 (K48), METTL3 (K48), G6PD, ERK1/2 (K27), PD-1 (K63), and many others—linking it to redox homeostasis, stress granule dynamics, pyroptosis, ferroptosis, DNA damage response, metabolism, and immune checkpoint regulation, with its own activity regulated by neddylation (UBE2M at K129/134), deubiquitination (USP28), acetylation (K351), phosphorylation (ERK2 at T396), and oxidation-induced oligomerization."},"narrative":{"mechanistic_narrative":"TRIM21 is a cytosolic RING-domain E3 ubiquitin ligase that doubles as a high-affinity intracellular Fc receptor, coupling antibody-mediated pathogen recognition to proteasomal destruction and innate immune activation [PMID:28049840, PMID:36996217, PMID:33258165, PMID:39455551]. As an effector of antibody-dependent intracellular neutralization, it intercepts antibody-coated viral and pathological protein targets entering the cytosol—including tau seeds, viral nucleoproteins, and adenoviral vectors—routing them for degradation through the proteasome and the AAA-ATPase p97/VCP while inducing innate/intrinsic immune gene programs [PMID:28049840, PMID:36996217, PMID:30209217, PMID:33258165, PMID:39455551]. Mechanistically, productive degradation requires ubiquitination of the target protein itself rather than TRIM21 self-ubiquitination, and substrate clustering or multimerization activates the ligase—a principle exploited by Trim-Away, PROTAC, and molecular-glue degraders that recruit TRIM21 to substrates such as nuclear pore proteins [PMID:39488207, PMID:36807144, PMID:40247740]. Beyond antiviral defense, TRIM21 ubiquitinates a broad substrate repertoire using distinct chain linkages with opposing fates: K48-linked chains drive proteasomal degradation of substrates including SAMHD1, VDAC2, METTL3, mutant p53, and lipogenic regulators (SREBF1, ChREBP, FASN) [PMID:31797533, PMID:36797289, PMID:36749630, PMID:40175350, PMID:37937648, PMID:36694250], whereas K63-linked chains modify p62/SQSTM1, G3BP1, CLASPIN, FSP1, PD-1, and others to alter their oligomerization, localization, or stability without necessarily destroying them [PMID:26942676, PMID:36692217, PMID:35048968, PMID:37587773, PMID:39905727]. Through these substrates TRIM21 governs redox homeostasis via p62/Keap1-Nrf2 [PMID:26942676, PMID:39172027], stress-granule phase separation [PMID:36692217], the replication-checkpoint and DNA damage response [PMID:35048968], ferroptosis through GPX4, FSP1, and METTL3 [PMID:37587773, PMID:36958437, PMID:40175350], pyroptosis via GSDMD [PMID:34511601], metabolic flux (pentose phosphate pathway, lipogenesis) [PMID:32312982, PMID:37937648], and immune-checkpoint and tumor immune evasion through PD-1 and CD47 [PMID:39905727, PMID:37541303]. TRIM21's own activity is tuned by post-translational regulation: neddylation by UBE2M at K129/K134 [PMID:37343564], acetylation at K351 [PMID:35770730], ERK2 phosphorylation at T396 [PMID:39388269], oxidation-induced disulfide oligomerization at C92/C111/C114 [PMID:39172027], and deubiquitination/stabilization by USP28 [PMID:39431010].","teleology":[{"year":2016,"claim":"Established that beyond immunity TRIM21 controls redox homeostasis by K63-ubiquitinating p62/SQSTM1, defining a direct cellular substrate and an antioxidant-suppressing function.","evidence":"Co-IP, K7 site mutagenesis, in vitro ubiquitination, and Trim21-knockout mouse injury models","pmids":["26942676"],"confidence":"High","gaps":["Did not resolve how oxidative state feeds back onto TRIM21 activity","Linkage of p62 modification to broader Nrf2 dynamics not fully mapped"]},{"year":2017,"claim":"Defined TRIM21 as a cytosolic Fc receptor capable of neutralizing antibody-bound pathological protein seeds (tau), extending intracellular antibody immunity beyond intact pathogens.","evidence":"Fluorescent seeding assays with TRIM21 manipulation and proteasome/p97 inhibition","pmids":["28049840","36996217"],"confidence":"High","gaps":["Did not establish whether tau is directly ubiquitinated by TRIM21","Role of p97/VCP versus proteasome in seed disassembly not separated"]},{"year":2018,"claim":"Demonstrated in vivo that TRIM21 enforces antibody-dependent blockade of viral gene delivery and drives broad innate immune transcription, linking the Fc-receptor function to organismal antiviral defense.","evidence":"TRIM21 knockout mice, antibody point mutant, and transcriptomics of transduced tissue","pmids":["30209217"],"confidence":"High","gaps":["Direct degradation substrate within the adenoviral particle not defined","Mechanism connecting degradation to immune gene induction unresolved"]},{"year":2020,"claim":"Showed TRIM21-mediated antigen degradation can prime cytotoxic T cells (ADIN) and that TRIM21 degrades antiviral and metabolic substrates, broadening its functions to T-cell immunity and metabolism.","evidence":"TRIM21 KO mice with LCMV/CTL assays, plus KO/OE ubiquitination studies of SAMHD1, G6PD, and HBV Pol","pmids":["33258165","31797533","32312982","32245233"],"confidence":"High","gaps":["How antigen routing to MHC-I presentation is coordinated with degradation not resolved","PI3K/AKT regulation of TRIM21 toward G6PD only partially mapped"]},{"year":2022,"claim":"Revealed that TRIM21 uses linkage-specific ubiquitination (K63 on CLASPIN, K27 on ERK1/2) to regulate the replication checkpoint and kinase signaling rather than simply degrade substrates.","evidence":"Co-IP, linkage-specific ubiquitination assays, catalytic-mutant controls, and replication-fork/CHK1 and ERK signaling readouts","pmids":["35048968","39533840"],"confidence":"High","gaps":["Structural basis for chain-linkage selection unknown","Context determining degradative versus non-degradative outcome not defined"]},{"year":2023,"claim":"Cell-free reconstitution proved that target-protein ubiquitination, not TRIM21 self-ubiquitination, is the obligatory step for substrate proteolysis, correcting the prior mechanistic model.","evidence":"Xenopus egg extract Trim-Away with chemical methylation of TRIM21 and target lysine-deletion mutagenesis","pmids":["36807144"],"confidence":"High","gaps":["Whether self-ubiquitination contributes to activation upstream of target modification not fully excluded","E2 enzyme selectivity in extract not defined"]},{"year":2023,"claim":"Mapped TRIM21 as a hub of cell-death and redox decisions through K63/K48 modification of G3BP1, FSP1, GPX4, METTL3, VDAC2, and oxidation-sensing of its own activity.","evidence":"Co-IP, site-specific ubiquitination assays, in vitro LLPS reconstitution, membrane fractionation, and Cys-to-Ser oxidation mutagenesis with KO models","pmids":["36692217","37587773","36958437","40175350","36797289","39172027"],"confidence":"High","gaps":["Tissue/context determinants directing pro- versus anti-ferroptotic outcomes unresolved","How oxidation-induced oligomerization is reversed in cells not defined"]},{"year":2023,"claim":"Identified upstream regulators (UBE2M neddylation at K129/134, SIRT5-dependent K351 acetylation, USP28 stabilization) that tune TRIM21 ligase output in inflammation and cardiac stress.","evidence":"Site-specific neddylation/acetylation mutagenesis, deubiquitination assays, and macrophage- or cardiomyocyte-specific KO mouse models","pmids":["37343564","35770730","39431010"],"confidence":"High","gaps":["Crosstalk hierarchy among the multiple PTMs is unknown","Whether modifications alter substrate selectivity versus global activity unresolved"]},{"year":2024,"claim":"Established TRIM21 as a tractable degradation effector whose dependence on substrate clustering enables molecular glues and PROTACs, validated structurally against nuclear pore proteins.","evidence":"DEL/molecular-glue screens, crystallography of TRIM21-NUP98 and TRIM21-ligand interfaces, proteomics, and KO controls","pmids":["39488207","40247740"],"confidence":"High","gaps":["Generalizability of clustering requirement across non-condensate substrates not fully defined","Endogenous physiological glue-like activators unknown"]},{"year":2024,"claim":"Extended TRIM21 into immune-checkpoint and tumor immune-evasion control via K63-stabilization of PD-1 and degradation of CD47, with ERK2 T396 phosphorylation gating substrate engagement.","evidence":"Site/linkage-specific ubiquitination mutagenesis, knock-in alleles, Trim21 KO mice, and tumor immunotherapy models","pmids":["39905727","37541303","39388269"],"confidence":"High","gaps":["Why some substrates are stabilized (K63) while structurally similar ones are degraded not mechanistically explained","Therapeutic window of TRIM21 modulation in immunity untested"]},{"year":null,"claim":"It remains unknown what determines TRIM21's choice of ubiquitin chain linkage and degradative versus non-degradative substrate fate across its very broad substrate set.","evidence":"No timeline study resolves the structural or regulatory logic unifying the diverse substrate and linkage outcomes","pmids":[],"confidence":"Medium","gaps":["No unifying structural model for linkage selection","Substrate-selectivity rules across tissues undefined","Interplay of the multiple regulatory PTMs in vivo unmapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,7,8,10,11,12,31]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,6,7,11,26]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[0,2,10,11,26]},{"term_id":"GO:0001618","term_label":"virus receptor activity","supporting_discovery_ids":[1,5,43]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,5,8]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1,3,5,6,43]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,2,7,11,26]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,12,13,21]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,8,22]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[4,23,42]}],"complexes":[],"partners":["SQSTM1","G3BP1","GSDMD","CLASPIN","VDAC2","FSP1","PD-1","ERK1/2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P19474","full_name":"E3 ubiquitin-protein ligase TRIM21","aliases":["52 kDa Ro protein","52 kDa ribonucleoprotein autoantigen Ro/SS-A","RING finger protein 81","Ro(SS-A)","Sjoegren syndrome type A antigen","SS-A","Tripartite motif-containing protein 21"],"length_aa":475,"mass_kda":54.2,"function":"E3 ubiquitin-protein ligase whose activity is dependent on E2 enzymes, UBE2D1, UBE2D2, UBE2E1 and UBE2E2 (PubMed:16297862, PubMed:16316627, PubMed:16472766, PubMed:16880511, PubMed:18022694, PubMed:18361920, PubMed:18641315, PubMed:18845142, PubMed:19675099, PubMed:26347139). Forms a ubiquitin ligase complex in cooperation with the E2 UBE2D2 that is used not only for the ubiquitination of USP4 and IKBKB but also for its self-ubiquitination (PubMed:16880511, PubMed:19675099). Component of cullin-RING-based SCF (SKP1-CUL1-F-box protein) E3 ubiquitin-protein ligase complexes such as SCF(SKP2)-like complexes (PubMed:16880511). A TRIM21-containing SCF(SKP2)-like complex is shown to mediate ubiquitination of CDKN1B ('Thr-187' phosphorylated-form), thereby promoting its degradation by the proteasome (PubMed:16880511). Monoubiquitinates IKBKB that will negatively regulates Tax-induced NF-kappa-B signaling (PubMed:19675099). Negatively regulates IFN-beta production post-pathogen recognition by catalyzing polyubiquitin-mediated degradation of IRF3 (PubMed:18641315). Mediates the ubiquitin-mediated proteasomal degradation of IgG1 heavy chain, which is linked to the VCP-mediated ER-associated degradation (ERAD) pathway (PubMed:18022694). Promotes IRF8 ubiquitination, which enhanced the ability of IRF8 to stimulate cytokine genes transcription in macrophages (By similarity). Plays a role in the regulation of the cell cycle progression (PubMed:16880511). Enhances the decapping activity of DCP2 (PubMed:18361920). Exists as a ribonucleoprotein particle present in all mammalian cells studied and composed of a single polypeptide and one of four small RNA molecules (PubMed:1985094, PubMed:8666824). At least two isoforms are present in nucleated and red blood cells, and tissue specific differences in RO/SSA proteins have been identified (PubMed:8666824). The common feature of these proteins is their ability to bind HY RNAs.2 (PubMed:8666824). Involved in the regulation of innate immunity and the inflammatory response in response to IFNG/IFN-gamma (PubMed:26347139). Organizes autophagic machinery by serving as a platform for the assembly of ULK1, Beclin 1/BECN1 and ATG8 family members and recognizes specific autophagy targets, thus coordinating target recognition with assembly of the autophagic apparatus and initiation of autophagy (PubMed:26347139). Also regulates autophagy through FIP200/RB1CC1 ubiquitination and subsequent decreased protein stability (PubMed:36359729). Represses the innate antiviral response by facilitating the formation of the NMI-IFI35 complex through 'Lys-63'-linked ubiquitination of NMI (PubMed:26342464). During viral infection, promotes cell pyroptosis by mediating 'Lys-6'-linked ubiquitination of ISG12a/IFI27, facilitating its translocation into the mitochondria and subsequent CASP3 activation (PubMed:36426955). When up-regulated through the IFN/JAK/STAT signaling pathway, promotes 'Lys-27'-linked ubiquitination of MAVS, leading to the recruitment of TBK1 and up-regulation of innate immunity (PubMed:29743353). Mediates 'Lys-63'-linked polyubiquitination of G3BP1 in response to heat shock, leading to stress granule disassembly (PubMed:36692217)","subcellular_location":"Cytoplasm; Cytoplasmic vesicle, autophagosome; Nucleus; Cytoplasm, P-body; Cytoplasm, Stress granule","url":"https://www.uniprot.org/uniprotkb/P19474/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TRIM21","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TRIM21","total_profiled":1310},"omim":[{"mim_id":"617447","title":"PABP-DEPENDENT POLY(A) NUCLEASE 2; PAN2","url":"https://www.omim.org/entry/617447"},{"mim_id":"608487","title":"TRIPARTITE MOTIF-CONTAINING PROTEIN 5; TRIM5","url":"https://www.omim.org/entry/608487"},{"mim_id":"607564","title":"TRIPARTITE MOTIF-CONTAINING PROTEIN 6; TRIM6","url":"https://www.omim.org/entry/607564"},{"mim_id":"606124","title":"TRIPARTITE MOTIF-CONTAINING PROTEIN 49; TRIM49","url":"https://www.omim.org/entry/606124"},{"mim_id":"171840","title":"PHOSPHOFRUCTOKINASE, PLATELET TYPE; PFKP","url":"https://www.omim.org/entry/171840"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TRIM21"},"hgnc":{"alias_symbol":["RNF81","RO52"],"prev_symbol":["SSA1"]},"alphafold":{"accession":"P19474","domains":[{"cath_id":"3.30.40.10","chopping":"1-112","consensus_level":"medium","plddt":84.0586,"start":1,"end":112},{"cath_id":"-","chopping":"149-255","consensus_level":"high","plddt":95.0438,"start":149,"end":255},{"cath_id":"2.60.120.920","chopping":"277-461","consensus_level":"high","plddt":95.5101,"start":277,"end":461}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P19474","model_url":"https://alphafold.ebi.ac.uk/files/AF-P19474-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P19474-F1-predicted_aligned_error_v6.png","plddt_mean":90.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRIM21","jax_strain_url":"https://www.jax.org/strain/search?query=TRIM21"},"sequence":{"accession":"P19474","fasta_url":"https://rest.uniprot.org/uniprotkb/P19474.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P19474/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P19474"}},"corpus_meta":[{"pmid":"26942676","id":"PMC_26942676","title":"TRIM21 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irradiation-induced mitochondrial DNA release and impairs antitumour immunity in nasopharyngeal carcinoma tumour models.","date":"2023","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/36797289","citation_count":113,"is_preprint":false},{"pmid":"36692217","id":"PMC_36692217","title":"Stress granule homeostasis is modulated by TRIM21-mediated ubiquitination of G3BP1 and autophagy-dependent elimination of stress granules.","date":"2023","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/36692217","citation_count":95,"is_preprint":false},{"pmid":"37343564","id":"PMC_37343564","title":"UBE2M-mediated neddylation of TRIM21 regulates obesity-induced inflammation and metabolic disorders.","date":"2023","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/37343564","citation_count":95,"is_preprint":false},{"pmid":"33508433","id":"PMC_33508433","title":"TRIM21 - A potential novel therapeutic target in cancer.","date":"2021","source":"Pharmacological 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\"TRIM21 directly interacts with SQSTM1/p62 and ubiquitylates p62 at lysine 7 (K7) via K63-linked ubiquitin chains, which abrogates p62 oligomerization and sequestration of client proteins (including Keap1), thereby suppressing the antioxidant response. TRIM21-deficient cells display enhanced antioxidant response and reduced cell death under oxidative stress.\",\n      \"method\": \"Co-IP, ubiquitination assay, mutagenesis (K7 site), genetic ablation in mice (liver insult and pressure overload models)\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — reciprocal Co-IP, site-specific mutagenesis, in vitro ubiquitination assay, and in vivo genetic ablation with defined phenotypic readout\",\n      \"pmids\": [\"26942676\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TRIM21 acts as a cytosolic Fc receptor that detects antibody-coated tau seeds entering the cell; after binding, TRIM21 neutralizes tau seeds through the proteasome and AAA ATPase p97/VCP, inhibiting pathological tau aggregate formation.\",\n      \"method\": \"Fluorescent morphology-based seeding assays, TRIM21 knockdown/overexpression, pharmacological inhibition of proteasome and p97/VCP\",\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 (seeding assay, proteasome/p97 inhibitors, TRIM21 manipulation) in a single study; replicated in subsequent in vivo work (PMID 36996217)\",\n      \"pmids\": [\"28049840\", \"36996217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TRIM21 interacts with SAMHD1 and promotes its K48-linked ubiquitination and proteasomal degradation, thereby reducing SAMHD1-dependent restriction of EV71 and HIV-1 replication. The SPRY domain of TRIM21 is required for SAMHD1 binding and K622 of SAMHD1 is the ubiquitination site.\",\n      \"method\": \"Co-IP, in vitro ubiquitination assay, domain-deletion mutants, neonatal mouse model\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — Co-IP, ubiquitination assay, mutagenesis of binding/ubiquitination sites, in vivo mouse model; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"31797533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TRIM21 mediates antibody-dependent inhibition of adenoviral gene delivery in vivo; genetic KO of TRIM21 or a single antibody point mutation restores transgene expression. TRIM21 is also responsible for blocking cytotoxic T cell induction by adenoviral vaccine vectors and for upregulating hundreds of innate/intrinsic immune genes in vector-transduced tissue.\",\n      \"method\": \"TRIM21 genetic knockout mice, antibody point mutant, transcriptomic analysis of transduced tissue, viral challenge models\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with defined in vivo phenotype, antibody mutagenesis, transcriptomics; multiple orthogonal approaches in single study\",\n      \"pmids\": [\"30209217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIM21 functions as an E3 ubiquitin ligase targeting G6PD for degradation, thereby negatively regulating the pentose phosphate pathway (PPP). PI3K/AKT activation inhibits TRIM21 to stabilize G6PD and promote PPP flux. Knockout of TRIM21 promotes PPP activity and cell proliferation.\",\n      \"method\": \"TRIM21 knockout/overexpression, ubiquitination assays, PTEN-null cancer cell models and murine in vivo models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO and OE with functional readouts, in vivo models; single lab, mechanism partially inferred\",\n      \"pmids\": [\"32312982\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIM21 uses anti-nucleoprotein (N) antibodies to target viral N protein for cytosolic degradation and generate cytotoxic T cells against N peptide, providing T cell-mediated viral clearance via antibody-dependent intracellular neutralization (ADIN) in LCMV infection.\",\n      \"method\": \"TRIM21 KO mice, LCMV infection model, CTL assays, antibody transfer experiments\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO mice with viral challenge, multiple functional readouts (viral clearance, CTL induction); in vivo and in vitro orthogonal methods\",\n      \"pmids\": [\"33258165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TRIM21 interacts with GSDMD via its PRY-SPRY domain, maintaining GSDMD stable expression in resting cells and inducing GSDMD-N terminus aggregation during pyroptosis, thereby acting as a positive regulator of GSDMD-dependent pyroptosis. TRIM21-deficient cells show reduced pyroptosis in response to NLRP3 or NLRC4 inflammasome activation, and TRIM21 KO mice are protected from LPS-induced inflammation and DSS-induced colitis.\",\n      \"method\": \"Co-IP (PRY-SPRY domain mapping), TRIM21 KO cells and mice, inflammasome activation assays, colitis model\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with domain mapping, KO cells with defined pyroptosis phenotype, in vivo mouse models; multiple orthogonal methods\",\n      \"pmids\": [\"34511601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 promotes K48-linked ubiquitination and proteasomal degradation of VDAC2, inhibiting VDAC2 oligomer pore formation and thereby blocking mitochondrial DNA release and cGAS/STING pathway activation following irradiation in nasopharyngeal carcinoma cells.\",\n      \"method\": \"TRIM21 KO, Co-IP, ubiquitination assay, mitochondrial DNA release assay, cGAS/STING pathway readouts, in vivo tumor models\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO with defined mechanistic pathway, reciprocal Co-IP, ubiquitination assay, multiple in vitro and in vivo readouts\",\n      \"pmids\": [\"36797289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 catalyzes K63-linked ubiquitination of the stress granule core protein G3BP1, which effectively inhibits G3BP1 liquid-liquid phase separation (LLPS) and stress granule formation in vitro and in cells.\",\n      \"method\": \"E3 ligase screen in SGs, Co-IP, in vitro LLPS assay, TRIM21 knockdown/overexpression, ubiquitination assay\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro LLPS reconstitution with ubiquitinated G3BP1, Co-IP, KD/OE cellular phenotype; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"36692217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"UBE2M (E2 enzyme) neddylates TRIM21 at K129/K134; this neddylation promotes TRIM21-mediated K48-linked ubiquitination and degradation of VHL, which prevents VHL-dependent degradation of HIF-1α and sustains IL-1β production in macrophages during obesity-induced inflammation.\",\n      \"method\": \"UBE2M KO macrophage mice, neddylation assay, Co-IP, ubiquitination assay, HFD mouse models\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — neddylation site-specific mutagenesis (K129/134), Co-IP, ubiquitination assay, in vivo KO models; multiple orthogonal methods\",\n      \"pmids\": [\"37343564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIM21 directly interacts with and ubiquitinates CLASPIN via K63-linked chains, which counteracts the K6-linked ubiquitination of CLASPIN essential for its interaction with TIPIN and chromatin loading. Overexpression of TRIM21 (but not a catalytically inactive mutant) compromises CHK1 activation, leading to replication fork instability.\",\n      \"method\": \"Co-IP, ubiquitination assay, catalytically inactive TRIM21 mutant, CHK1 activation assays, replication fork assays\",\n      \"journal\": \"Nucleic acids research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — Co-IP, ubiquitination assay with linkage-specific analysis, catalytic mutant control, functional replication fork readout; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35048968\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 identified as an E3 ubiquitin ligase for mutant p53 (mutp53); it directly interacts with mutp53 but not wild-type p53, promoting mutp53 ubiquitination and proteasomal degradation to suppress mutp53 gain-of-function in tumorigenesis. TRIM21 deletion in p53R172H knockin mice caused mutp53 accumulation in normal tissues and earlier tumor onset.\",\n      \"method\": \"mutp53-interacting protein screen, Co-IP, ubiquitination assay, TRIM21 KO in p53R172H knockin mice\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — protein screen, Co-IP, ubiquitination assay, in vivo genetic mouse model with defined tumor phenotype; multiple orthogonal methods\",\n      \"pmids\": [\"36749630\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 mediates K63-linked ubiquitination of FSP1 at K322 and K366 residues, which is essential for FSP1 plasma membrane translocation and its ferroptosis suppression activity.\",\n      \"method\": \"Co-IP, ubiquitination assay with site-directed mutagenesis (K322R, K366R), membrane fractionation, RSL3-induced ferroptosis assays, subcutaneous tumor model\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — site-specific mutagenesis, ubiquitination assay, membrane fractionation to link modification to localization change; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37587773\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 ubiquitylates GPX4, promoting its degradation, and thereby promotes ferroptosis in ischemia/reperfusion-induced acute kidney injury. TRIM21 KO mice are protected from I/R-AKI with upregulated GPX4.\",\n      \"method\": \"Co-IP, ubiquitination assay, Trim21-/- mice I/R model, H/R cell model, ferroptosis markers\",\n      \"journal\": \"Life sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO mouse model with defined phenotype; single lab\",\n      \"pmids\": [\"36958437\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 directly interacts with SARS-CoV-2 nucleocapsid (N) protein and ubiquitinates it at K375, leading to proteasomal degradation. This ubiquitination was also observed for N proteins of SARS-CoV-2 variants and related coronaviruses.\",\n      \"method\": \"Immunoprecipitation/mass spectrometry, Co-IP, ubiquitination assay, proteasome inhibitor experiments\",\n      \"journal\": \"Journal of medical virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP-MS identification, Co-IP, site-mapped ubiquitination assay; single lab\",\n      \"pmids\": [\"37185839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIM21 interacts with the TP domain of HBV DNA polymerase (Pol) via its SPRY domain and promotes ubiquitination at K260 and K283 of HBV Pol using its RING domain, leading to proteasomal degradation and restriction of HBV DNA replication.\",\n      \"method\": \"FLAG affinity purification/mass spectrometry, Co-IP, ubiquitination assay, domain deletion mutants, HBV replication assays\",\n      \"journal\": \"Viruses\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity purification/MS, Co-IP, site-specific ubiquitination mapping with mutagenesis, functional replication assay; single lab\",\n      \"pmids\": [\"32245233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIM21 promotes K48-linked ubiquitination of IRF7, leading to its degradation, to promote rabies virus (RABV) replication via the IRF7-IFN axis; TRIM21 knockdown inhibits RABV replication while overexpression promotes it.\",\n      \"method\": \"TRIM21 knockdown/overexpression, Co-IP, ubiquitination assay, IFN production assays, RABV replication assays\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD/OE with functional viral replication readout, Co-IP, IRF7 degradation assay; single lab\",\n      \"pmids\": [\"37446070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIM21 directly interacts with STAT1 and acts as its E3 ubiquitin ligase, promoting STAT1 ubiquitination and degradation. TGM2 (in a GTP-binding-dependent manner) facilitates dissociation of TRIM21 from STAT1, thereby stabilizing STAT1 and promoting gastric cancer progression.\",\n      \"method\": \"Co-IP, mass spectrometry, ubiquitination assay, TGM2 mutagenesis, TGM2-STAT1-TRIM21 interaction studies\",\n      \"journal\": \"Cancer communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, MS-identified interaction, ubiquitination assay, enzyme activity mutagenesis; single lab\",\n      \"pmids\": [\"36353796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LPS challenge promotes the interaction between TRIM21 and SIRT5, leading to TRIM21-mediated SIRT5 ubiquitination and degradation. SIRT5 degradation sustains acetylation of TRIM21 at K351, increasing its E3 ligase activity in LPS-activated macrophages and enhancing IL-1β production.\",\n      \"method\": \"Co-IP, ubiquitination assay, deubiquitinase (HAUSP) competition assay, K351 acetylation mapping, IL-1β ELISA, DSS colitis model\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, acetylation site mutagenesis, in vivo colitis model; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35770730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Mtb infection promotes TRIM21-mediated proteasomal degradation of HERC2 (an E3 ligase of NCOA4), via p38/AKT1 signaling, which stabilizes NCOA4 and enhances NCOA4-mediated ferritin degradation (ferritinophagy), increasing iron bioavailability for intracellular Mtb growth.\",\n      \"method\": \"Co-IP, ubiquitination assay, NCOA4 KO myeloid mice, HERC2 degradation assays, Mtb infection models\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, genetic KO mice with bacterial clearance readout; single lab\",\n      \"pmids\": [\"37066876\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 directly interacts with and ubiquitinates MST2 at K473 via K63-linked chains, enabling MST2 homodimer formation and enhanced MST2 kinase activity, ultimately inactivating YAP and inhibiting EMT in colorectal cancer.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis, MST2 kinase activity assay, YAP phosphorylation readout, mouse CRC models and organoids\",\n      \"journal\": \"Cell chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — Co-IP, site-specific ubiquitination mutagenesis, kinase activity assay, in vivo tumor models; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37354905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 promotes K48-linked ubiquitination of METTL3 at K459, leading to its proteasomal degradation, thereby promoting ferroptosis by preventing SLC7A11 mRNA stabilization in pancreatic cancer.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis (K459), ferroptosis assays, in vivo pancreatic cancer models\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, site-specific ubiquitination, KO/OE with ferroptosis readout; single lab\",\n      \"pmids\": [\"40175350\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 interacts with and ubiquitinates SQSTM1/p62 at K7 via K63 linkage, abolishing TBK1-mediated phosphorylation of p62 at S403 and preventing p62 aggregation. TRIM21 is oxidized at C92, C111, C114 to form disulfide bonds causing oligomerization and reduced E3 activity, which in turn allows S403 phosphorylation and p62-mediated antioxidant sequestration.\",\n      \"method\": \"Co-IP, ubiquitination assay, phosphorylation assay, Cys-to-Ser mutagenesis, in vitro dimerization assay, PA-treated MEF and mouse models\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple site-specific mutagenesis, in vitro biochemical assays, KO mouse models with defined phenotype; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"39172027\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 ubiquitinates ChREBP, SREBP1, ACC1, FASN, and A1CF (key lipogenesis and fructose metabolism regulators) via ubiquitin-mediated proteasomal degradation, limiting de novo lipogenesis in NASH. TRIM21 expression is induced by TNF-α plus fatty acids synergistically.\",\n      \"method\": \"Co-IP, ubiquitination assay, TRIM21 KO/OE in primary hepatocytes and mice, metabolic phenotyping\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, in vivo KO phenotype; single lab, multiple substrates identified\",\n      \"pmids\": [\"37937648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 directly interacts with c-Myc and ubiquitinates it at K148 via K63-linked chains, enabling c-Myc targeting to the autophagy machinery for degradation. ERK2 (downstream of mutant KRAS) phosphorylates TRIM21 at T396, disrupting the TRIM21-c-Myc interaction and preventing c-Myc autophagic degradation.\",\n      \"method\": \"Co-IP, ubiquitination assay (K63, K148 site mutagenesis), ERK2 phosphorylation assay (T396), autophagy flux assays, KRAS-mutant CRC models\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — multiple site-specific mutagenesis, Co-IP, phosphorylation assay, autophagy flux readout, in vivo models; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"39388269\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"(S)-ACE-OH acts as a molecular glue to induce TRIM21-NUP98 interaction, leading to ubiquitin-proteasome-dependent degradation of nuclear pore proteins and disruption of nucleocytoplasmic trafficking. TRIM21-based PROTACs enable selective degradation of multimeric/condensate proteins, consistent with a requirement for substrate clustering for TRIM21 activation.\",\n      \"method\": \"Co-IP, crystallography (TRIM21-NUP98 interface), proteomic studies, proteasome inhibitor experiments, TRIM21 KO validation\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystallographic structure of TRIM21-NUP98 interface, multiple molecular glue degraders validated, proteomic confirmation, KO controls\",\n      \"pmids\": [\"39488207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21-dependent target protein ubiquitination (not TRIM21 self-ubiquitination) is required for Trim-Away degradation, as demonstrated in Xenopus egg cell-free extracts; chemical methylation of TRIM21 had no effect on target proteolysis, whereas deletion of all lysines in target protein abolished ubiquitination and proteasomal degradation.\",\n      \"method\": \"Cell-free Xenopus egg extract system, chemical methylation of TRIM21, target protein lysine-deletion mutagenesis, proteasomal degradation assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution, chemical mutagenesis, target protein mutagenesis; mechanistically definitive study challenging prior models\",\n      \"pmids\": [\"36807144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIM21 promotes K63-linked ubiquitination of ISG12a and facilitates its translocation into mitochondria, causing caspase 3 activation; caspase 3 then cleaves GSDME specifically during viral infection, releasing GSDME N-terminal domain and causing pyroptosis.\",\n      \"method\": \"Co-IP, ubiquitination assay, mitochondrial fractionation, caspase 3 activation assay, GSDME cleavage assay, viral infection model\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, subcellular fractionation linked to functional pyroptosis readout; single lab\",\n      \"pmids\": [\"36426955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 interacts with EPHX1 through its SPRY domain and promotes K33- and K48-linked ubiquitination at K105 of EPHX1, leading to its degradation and inhibition of arachidonic acid metabolism in pancreatic cancer.\",\n      \"method\": \"Proteomics, ubiquitomics, LC-MS/MS, Co-IP, SPRY domain mapping, ubiquitination assay with site mutagenesis\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multi-omic approach, Co-IP, domain mapping, site-specific ubiquitination; single lab\",\n      \"pmids\": [\"39739616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 interacts with and promotes K48-linked ubiquitination-dependent degradation of NCL (nucleolin) at K239, suppressing HCC metastasis; circ0006646 prevents NCL-TRIM21 interaction to protect NCL from degradation.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis (K239), circ0006646 silencing, multi-omics, in vivo xenograft\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, site-specific ubiquitination assay, in vivo models; single lab\",\n      \"pmids\": [\"38357830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 restricts influenza A virus subtypes H3/H5/H9 (but not H1/H7) by binding to residue R95 of M1 matrix protein and facilitating K48-linked ubiquitination of M1 K242 for proteasomal degradation. Recombinant viruses with M1 R95K or K242R mutations were resistant to TRIM21.\",\n      \"method\": \"Co-IP, ubiquitination assay, site-directed mutagenesis (R95K, K242R), proteasomal degradation assays, recombinant virus rescue\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — Co-IP, site-specific mutagenesis validated by recombinant virus rescue, ubiquitination linkage mapping; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"37343022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 promotes K63-linked ubiquitination of PD-1 at K233, stabilizing PD-1 by antagonizing its K48-linked ubiquitination and degradation. Trim21 KO significantly decreases PD-1 expression, enhances CD8+ T cell activation, and sensitizes tumors to anti-CTLA-4 immunotherapy.\",\n      \"method\": \"Co-IP, ubiquitination assay with linkage and site (K233) mutagenesis, Trim21 KO mice, CD8+ T cell activation assays, in vivo tumor models\",\n      \"journal\": \"Molecular therapy\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-specific ubiquitination mutagenesis, reciprocal Co-IP, KO mouse models with defined immunological phenotype; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"39905727\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 promotes K63-linked ubiquitination of TAT (tyrosine aminotransferase) at K136 via interaction involving H336/H338 of TRIM21; this ubiquitination impairs TAT dimerization and mitochondrial localization, inhibiting cardiolipin-dependent mitophagy and GBC liver metastasis.\",\n      \"method\": \"Co-IP with TRIM21 domain mutagenesis (H336/H338), ubiquitination assay (K63, K136), TAT dimerization assay, mitochondrial localization assay, in vivo metastasis model\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with binding site mutagenesis, ubiquitination assay, localization readout; single lab\",\n      \"pmids\": [\"38697462\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 mediates K63-linked ubiquitination and lysosomal degradation of AXL receptor; STAMBPL1 (a deubiquitinase) antagonizes this to stabilize AXL, promoting EMT and immune evasion in kidney renal clear cell carcinoma.\",\n      \"method\": \"Co-IP, ubiquitination assay (K63 linkage), lysosomal inhibitor experiments, STAMBPL1 KD with rescue experiments\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination linkage assay, lysosomal pathway validation, deubiquitinase rescue; single lab\",\n      \"pmids\": [\"39527690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"EGFR activation induces c-Src-mediated phosphorylation of CD47 at Y288, which inhibits TRIM21-mediated K99/K102 polyubiquitylation and degradation of CD47, leading to CD47 accumulation and tumor immune evasion.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis (Y288F, K99/102R knock-in), macrophage phagocytosis assay, in vivo brain tumor model\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knock-in mutagenesis, Co-IP, ubiquitination assay, in vivo tumor model with immune readout; multiple orthogonal methods\",\n      \"pmids\": [\"37541303\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Small-molecule ligands to TRIM21 identified by DEL technology; crystallography confirmed ligand interaction with TRIM21. Treatment induced TRIM21-dependent, ubiquitin-proteasome-dependent degradation of NUP155 (primary target) and GLE1 (passenger), impairing nuclear envelope integrity.\",\n      \"method\": \"DNA-Encoded Library screen, crystallography, proteomic profiling, TRIM21 KO validation, proteasome inhibitor, immunofluorescence\",\n      \"journal\": \"ACS chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure of TRIM21-ligand complex, proteomic validation, KO controls, mechanistic pathway defined; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"40247740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"USP28 deubiquitinates and stabilizes TRIM21 in cardiomyocytes; stabilized TRIM21 negatively regulates Nrf2 antioxidant response, increasing oxidative stress and promoting cardiac hypertrophy. USP28 CKO protects against Ang II- and TAC-induced cardiac dysfunction.\",\n      \"method\": \"Co-IP/mass spectrometry (substrate screen), cardiomyocyte-specific USP28 KO mice, deubiquitination assay, Nrf2 pathway readout, cardiac hypertrophy models\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS, KO mouse model with defined cardiac phenotype, deubiquitination assay; single lab\",\n      \"pmids\": [\"39431010\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CDK2 phosphorylates PXR at Ser350, promoting PXR dissociation from Hsp90/DNAJC7 and subsequent TRIM21-mediated PXR ubiquitination and proteasomal degradation.\",\n      \"method\": \"Co-IP, ubiquitination assay, CDK2 kinase assay, PXR-S350 phosphorylation site mutagenesis, Hsp90/DNAJC7 interaction assay\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, phosphorylation site mutagenesis; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35053380\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 interacts with ERK1/2 through its PRY-SPRY domain and catalyzes K27-linked ubiquitination of ERK1/2; this ubiquitination promotes ERK1/2-MEK1/2 interaction and subsequent ERK1/2 phosphorylation. Excess TRIM21 suppresses ERK1/2 phosphorylation by activating negative feedback pathways.\",\n      \"method\": \"CRISPR-Cas9 screen, Co-IP with domain mapping (PRY-SPRY), ubiquitination assay (K27 linkage), NanoBiT protein interaction assay, RNA-seq\",\n      \"journal\": \"Neuro-oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR screen, Co-IP with domain mapping, linkage-specific ubiquitination; single lab\",\n      \"pmids\": [\"39533840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 interacts with ACSL4 and promotes its ubiquitination and degradation; USP15 (deubiquitinase) counteracts this by deubiquitinating and stabilizing ACSL4. The balance between TRIM21 and USP15 determines ACSL4 levels and imatinib sensitivity in gastrointestinal stromal tumors.\",\n      \"method\": \"Co-IP, ubiquitination assay, deubiquitination assay, shRNA knockdown, xenograft mouse model\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination/deubiquitination assays, in vivo xenograft; single lab\",\n      \"pmids\": [\"38182686\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 interacts with and promotes K48-linked ubiquitination of CNOT4 at K239 (via K48 and K6 linkage) when complexed with TNKS1BP1, leading to CNOT4 degradation and downstream autophagy/lipid reprogramming effects in HCC.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis (K239), mass spectrometry, in vivo HCC models\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, MS, site-specific ubiquitination assay; single lab\",\n      \"pmids\": [\"39019859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 catalyzes K48-linked ubiquitination of TRPV2 at K295 in myeloid cells, promoting TRPV2 lysosomal/proteasomal degradation and reducing viral spread. TRPV2-K295R mutant is resistant to TRIM21-dependent degradation and promotes viral infection more profoundly than wild-type TRPV2.\",\n      \"method\": \"Co-IP, ubiquitination assay with site mutagenesis (K295R), Trim21-/- mice, TRPV2 KO reconstitution, viral infection assays (HSV-1, VSV)\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — site-specific mutagenesis with reconstitution, KO mice, multiple viral models; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"38613787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 promotes K48-linked ubiquitination of SREBF1, leading to its proteasomal degradation and consequent downregulation of lipogenic enzyme expression (reducing lipid accumulation) in renal cell carcinoma.\",\n      \"method\": \"Co-IP, immunoprecipitation, ubiquitination assay, TRIM21 KO/OE, metabolomics, Oil Red O staining, in vivo orthotopic model\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO/OE with metabolic phenotype; single lab\",\n      \"pmids\": [\"36694250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ANTIBODIES targeting CCHFV nucleoprotein (NP) protect against lethal CCHFV challenge through TRIM21-dependent mechanisms (intracellular Fc receptor function); TRIM21-deficient vaccinated mice cannot control infection despite robust CCHFV-specific immunity. Passive transfer of NP-immune sera confers TRIM21-dependent protection.\",\n      \"method\": \"TRIM21 KO mice, passive serum transfer, Fc-gamma receptor and complement KO controls, lethal challenge model\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with in vivo lethal challenge, passive transfer, multiple receptor-deficient controls establishing TRIM21 specificity\",\n      \"pmids\": [\"39455551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 promotes ubiquitination of Sohlh2 and its proteasomal degradation, suppressing M2 macrophage polarization and triple-negative breast cancer progression.\",\n      \"method\": \"Co-IP, ubiquitination assay, TRIM21 KO/OE in macrophages, M2 polarization assays, in vivo metastasis model\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, KO/OE with defined cellular phenotype; single lab\",\n      \"pmids\": [\"38123542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM21 promotes K63-linked ubiquitination and promotes nuclear translocation of PKM2 in astrocytes; nuclear PKM2 phosphorylates STAT3 and NF-κB and interacts with c-Myc, promoting astrocyte activation and glycolysis in experimental autoimmune encephalomyelitis.\",\n      \"method\": \"Co-IP, ubiquitination assay, TRIM21 OE/KD in primary astrocytes, nuclear PKM2 activity assays, intracerebroventricular lentiviral KD, EAE mouse model\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, in vivo KD with disease model readout; single lab\",\n      \"pmids\": [\"39264698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TRIM21 mutually regulates TRIM8 via K48-linked ubiquitination: TRIM21 promotes proteasomal degradation of TRIM8, and TRIM8 reciprocally promotes degradation of TRIM21 via K48-linked ubiquitination.\",\n      \"method\": \"Co-IP, ubiquitination assay (K48 linkage), proteasome inhibitor experiments, expression correlation in NSCLC and RCC clinical samples\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, ubiquitination assay with linkage specificity; single lab\",\n      \"pmids\": [\"37914816\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRIM21 is a cytosolic RING-domain E3 ubiquitin ligase and high-affinity Fc receptor that intercepts antibody-coated pathogens entering the cytosol, targeting them for proteasomal destruction via K63-linked ubiquitination (requiring target protein polyubiquitination rather than TRIM21 self-ubiquitination), while simultaneously activating innate immune signaling; beyond its antiviral role, TRIM21 ubiquitinates a broad range of cellular substrates—including p62/SQSTM1 (K7, K63), IRF family members, GSDMD regulators, G3BP1 (K63), CLASPIN (K63), mutant p53, GPX4, FSP1 (K63), VDAC2 (K48), METTL3 (K48), G6PD, ERK1/2 (K27), PD-1 (K63), and many others—linking it to redox homeostasis, stress granule dynamics, pyroptosis, ferroptosis, DNA damage response, metabolism, and immune checkpoint regulation, with its own activity regulated by neddylation (UBE2M at K129/134), deubiquitination (USP28), acetylation (K351), phosphorylation (ERK2 at T396), and oxidation-induced oligomerization.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TRIM21 is a cytosolic RING-domain E3 ubiquitin ligase that doubles as a high-affinity intracellular Fc receptor, coupling antibody-mediated pathogen recognition to proteasomal destruction and innate immune activation [#1, #5, #43]. As an effector of antibody-dependent intracellular neutralization, it intercepts antibody-coated viral and pathological protein targets entering the cytosol—including tau seeds, viral nucleoproteins, and adenoviral vectors—routing them for degradation through the proteasome and the AAA-ATPase p97/VCP while inducing innate/intrinsic immune gene programs [#1, #3, #5, #43]. Mechanistically, productive degradation requires ubiquitination of the target protein itself rather than TRIM21 self-ubiquitination, and substrate clustering or multimerization activates the ligase—a principle exploited by Trim-Away, PROTAC, and molecular-glue degraders that recruit TRIM21 to substrates such as nuclear pore proteins [#25, #26, #35]. Beyond antiviral defense, TRIM21 ubiquitinates a broad substrate repertoire using distinct chain linkages with opposing fates: K48-linked chains drive proteasomal degradation of substrates including SAMHD1, VDAC2, METTL3, mutant p53, and lipogenic regulators (SREBF1, ChREBP, FASN) [#2, #7, #11, #21, #23, #42], whereas K63-linked chains modify p62/SQSTM1, G3BP1, CLASPIN, FSP1, PD-1, and others to alter their oligomerization, localization, or stability without necessarily destroying them [#0, #8, #10, #12, #31]. Through these substrates TRIM21 governs redox homeostasis via p62/Keap1-Nrf2 [#0, #22], stress-granule phase separation [#8], the replication-checkpoint and DNA damage response [#10], ferroptosis through GPX4, FSP1, and METTL3 [#12, #13, #21], pyroptosis via GSDMD [#6], metabolic flux (pentose phosphate pathway, lipogenesis) [#4, #23], and immune-checkpoint and tumor immune evasion through PD-1 and CD47 [#31, #34]. TRIM21's own activity is tuned by post-translational regulation: neddylation by UBE2M at K129/K134 [#9], acetylation at K351 [#18], ERK2 phosphorylation at T396 [#24], oxidation-induced disulfide oligomerization at C92/C111/C114 [#22], and deubiquitination/stabilization by USP28 [#36].\",\n  \"teleology\": [\n    {\n      \"year\": 2016,\n      \"claim\": \"Established that beyond immunity TRIM21 controls redox homeostasis by K63-ubiquitinating p62/SQSTM1, defining a direct cellular substrate and an antioxidant-suppressing function.\",\n      \"evidence\": \"Co-IP, K7 site mutagenesis, in vitro ubiquitination, and Trim21-knockout mouse injury models\",\n      \"pmids\": [\"26942676\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how oxidative state feeds back onto TRIM21 activity\", \"Linkage of p62 modification to broader Nrf2 dynamics not fully mapped\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined TRIM21 as a cytosolic Fc receptor capable of neutralizing antibody-bound pathological protein seeds (tau), extending intracellular antibody immunity beyond intact pathogens.\",\n      \"evidence\": \"Fluorescent seeding assays with TRIM21 manipulation and proteasome/p97 inhibition\",\n      \"pmids\": [\"28049840\", \"36996217\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish whether tau is directly ubiquitinated by TRIM21\", \"Role of p97/VCP versus proteasome in seed disassembly not separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Demonstrated in vivo that TRIM21 enforces antibody-dependent blockade of viral gene delivery and drives broad innate immune transcription, linking the Fc-receptor function to organismal antiviral defense.\",\n      \"evidence\": \"TRIM21 knockout mice, antibody point mutant, and transcriptomics of transduced tissue\",\n      \"pmids\": [\"30209217\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct degradation substrate within the adenoviral particle not defined\", \"Mechanism connecting degradation to immune gene induction unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed TRIM21-mediated antigen degradation can prime cytotoxic T cells (ADIN) and that TRIM21 degrades antiviral and metabolic substrates, broadening its functions to T-cell immunity and metabolism.\",\n      \"evidence\": \"TRIM21 KO mice with LCMV/CTL assays, plus KO/OE ubiquitination studies of SAMHD1, G6PD, and HBV Pol\",\n      \"pmids\": [\"33258165\", \"31797533\", \"32312982\", \"32245233\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How antigen routing to MHC-I presentation is coordinated with degradation not resolved\", \"PI3K/AKT regulation of TRIM21 toward G6PD only partially mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed that TRIM21 uses linkage-specific ubiquitination (K63 on CLASPIN, K27 on ERK1/2) to regulate the replication checkpoint and kinase signaling rather than simply degrade substrates.\",\n      \"evidence\": \"Co-IP, linkage-specific ubiquitination assays, catalytic-mutant controls, and replication-fork/CHK1 and ERK signaling readouts\",\n      \"pmids\": [\"35048968\", \"39533840\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for chain-linkage selection unknown\", \"Context determining degradative versus non-degradative outcome not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Cell-free reconstitution proved that target-protein ubiquitination, not TRIM21 self-ubiquitination, is the obligatory step for substrate proteolysis, correcting the prior mechanistic model.\",\n      \"evidence\": \"Xenopus egg extract Trim-Away with chemical methylation of TRIM21 and target lysine-deletion mutagenesis\",\n      \"pmids\": [\"36807144\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether self-ubiquitination contributes to activation upstream of target modification not fully excluded\", \"E2 enzyme selectivity in extract not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapped TRIM21 as a hub of cell-death and redox decisions through K63/K48 modification of G3BP1, FSP1, GPX4, METTL3, VDAC2, and oxidation-sensing of its own activity.\",\n      \"evidence\": \"Co-IP, site-specific ubiquitination assays, in vitro LLPS reconstitution, membrane fractionation, and Cys-to-Ser oxidation mutagenesis with KO models\",\n      \"pmids\": [\"36692217\", \"37587773\", \"36958437\", \"40175350\", \"36797289\", \"39172027\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue/context determinants directing pro- versus anti-ferroptotic outcomes unresolved\", \"How oxidation-induced oligomerization is reversed in cells not defined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified upstream regulators (UBE2M neddylation at K129/134, SIRT5-dependent K351 acetylation, USP28 stabilization) that tune TRIM21 ligase output in inflammation and cardiac stress.\",\n      \"evidence\": \"Site-specific neddylation/acetylation mutagenesis, deubiquitination assays, and macrophage- or cardiomyocyte-specific KO mouse models\",\n      \"pmids\": [\"37343564\", \"35770730\", \"39431010\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crosstalk hierarchy among the multiple PTMs is unknown\", \"Whether modifications alter substrate selectivity versus global activity unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established TRIM21 as a tractable degradation effector whose dependence on substrate clustering enables molecular glues and PROTACs, validated structurally against nuclear pore proteins.\",\n      \"evidence\": \"DEL/molecular-glue screens, crystallography of TRIM21-NUP98 and TRIM21-ligand interfaces, proteomics, and KO controls\",\n      \"pmids\": [\"39488207\", \"40247740\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generalizability of clustering requirement across non-condensate substrates not fully defined\", \"Endogenous physiological glue-like activators unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended TRIM21 into immune-checkpoint and tumor immune-evasion control via K63-stabilization of PD-1 and degradation of CD47, with ERK2 T396 phosphorylation gating substrate engagement.\",\n      \"evidence\": \"Site/linkage-specific ubiquitination mutagenesis, knock-in alleles, Trim21 KO mice, and tumor immunotherapy models\",\n      \"pmids\": [\"39905727\", \"37541303\", \"39388269\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why some substrates are stabilized (K63) while structurally similar ones are degraded not mechanistically explained\", \"Therapeutic window of TRIM21 modulation in immunity untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown what determines TRIM21's choice of ubiquitin chain linkage and degradative versus non-degradative substrate fate across its very broad substrate set.\",\n      \"evidence\": \"No timeline study resolves the structural or regulatory logic unifying the diverse substrate and linkage outcomes\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying structural model for linkage selection\", \"Substrate-selectivity rules across tissues undefined\", \"Interplay of the multiple regulatory PTMs in vivo unmapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 7, 8, 10, 11, 12, 31]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 6, 7, 11, 26]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0, 2, 10, 11, 26]},\n      {\"term_id\": \"GO:0001618\", \"supporting_discovery_ids\": [1, 5, 43]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 5, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1, 3, 5, 6, 43]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 2, 7, 11, 26]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 12, 13, 21]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 8, 22]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [4, 23, 42]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SQSTM1\", \"G3BP1\", \"GSDMD\", \"CLASPIN\", \"VDAC2\", \"FSP1\", \"PD-1\", \"ERK1/2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}