# TRIM21 Exacerbates Ischemic Brain Injury by Promoting Astrocyte-Mediated Neuroinflammation via K63-Linked Ubiquitination of MDA5

**Authors:** Yirui Kuang, Huaping Huang, Kaibo Yu, Tianchi Tang, Yonghe Zheng, Xian Yu, Linfeng Fan, Hang Zhou, Yin Li, Yinghan Guo, Yi Zhang, Fengqi Zhou, Jianru Li, Chi Gu, Junyou Wang, Liya Lin, Guannan Guan, Feng Yan, Gao Chen

PMC · DOI: 10.34133/research.1200 · Research · 2026-03-17

## TL;DR

TRIM21 worsens brain damage after stroke by boosting inflammation in astrocytes, and targeting TRIM21 could help treat ischemic stroke.

## Contribution

TRIM21 is identified as a novel astrocyte-specific mediator of neuroinflammation in cerebral ischemic injury.

## Key findings

- TRIM21 deficiency reduces cerebral ischemia/reperfusion injury by dampening inflammation and oxidative stress.
- TRIM21 promotes MDA5 stabilization via K63-linked ubiquitination, activating the NF-κB pathway in astrocytes.
- Brain-targeted TRIM21 silencing ameliorates cerebral I/R injury in mice.

## Abstract

The pathophysiology of ischemic stroke is critically mediated by detrimental neuroinflammation. Tripartite motif-containing 21 (TRIM21) serves as an E3 ubiquitin ligase that regulates important biological functions. Nonetheless, the specific role of TRIM21 in neuroinflammation and ischemic brain injury remains unclear. In this study, we found that TRIM21 expression was up-regulated in astrocytes within the peri-infarct regions of mice subjected to transient middle cerebral artery occlusion (tMCAO) and in an in vitro oxygen–glucose deprivation and reoxygenation (OGD/R) model. TRIM21 deficiency alleviated cerebral ischemia/reperfusion (I/R) injury by attenuating the inflammatory responses and oxidative stress. Mechanistically, our findings demonstrated that TRIM21 interacts with MDA5 and sequentially promotes the K63-linked ubiquitination and stabilization of MDA5, ultimately activating the nuclear factor κB (NF-κB) pathway in astrocytes. Moreover, MDA5 overexpression effectively reversed protective effects of TRIM21 deficiency after cerebral ischemia. Consistently, brain-targeted TRIM21 silencing with nanoparticle delivery considerably ameliorated cerebral I/R injury. Collectively, our findings identify TRIM21 as a novel astrocyte-specific mediator of neuroinflammation in cerebral ischemic injury and highlight its potential as a therapeutic target for ischemic stroke.

## Linked entities

- **Genes:** TRIM21 (tripartite motif containing 21) [NCBI Gene 6737], IFIH1 (interferon induced with helicase C domain 1) [NCBI Gene 64135], NFKB1 (nuclear factor kappa B subunit 1) [NCBI Gene 4790]
- **Proteins:** TRIM21 (tripartite motif containing 21), IFIH1 (interferon induced with helicase C domain 1)
- **Diseases:** ischemic stroke (MONDO:1060198), cerebral ischemia (MONDO:0002679)
- **Species:** Mus musculus (taxon 10090)

## Full-text entities

- **Genes:** Keap1 (kelch-like ECH-associated protein 1) [NCBI Gene 50868] {aka INRF2, mKIAA0132}, Trim9 (tripartite motif-containing 9) [NCBI Gene 94090], Tmprss11d (transmembrane protease, serine 11d) [NCBI Gene 231382] {aka AST, AsP}, Dnase1 (deoxyribonuclease I) [NCBI Gene 13419] {aka DNaseI, Dnl1}, Mavs (mitochondrial antiviral signaling protein) [NCBI Gene 228607] {aka D430028G21Rik, IPS-1, Visa, cardif}, Nfkb1 (nuclear factor of kappa light polypeptide gene enhancer in B cells 1, p105) [NCBI Gene 18033] {aka NF-KB1, NF-kappaB, NF-kappaB1, p105, p50, p50/p105}, TRIM21 (tripartite motif containing 21) [NCBI Gene 6737] {aka RNF81, RO52, Ro/SSA, SSA, SSA1, TRIM21/Ro52}, Gfap (glial fibrillary acidic protein) [NCBI Gene 14580], Iba1 (induction of brown adipocytes 1) [NCBI Gene 114737], Gja1 (gap junction protein, alpha 1) [NCBI Gene 14609] {aka Cnx43, Cx43, Cx43alpha1, Cxnk1, Gja-1, Npm1}, Trim16 (tripartite motif-containing 16) [NCBI Gene 94092] {aka 9130006M08Rik, EBBP}, Nfe2l2 (nuclear factor, erythroid derived 2, like 2) [NCBI Gene 18024] {aka Nrf2}, RELA (RELA proto-oncogene, NF-kB subunit) [NCBI Gene 5970] {aka AIF3BL3, CMCU, NFKB3, p65}, Rnf144b (ring finger protein 144B) [NCBI Gene 218215] {aka E130105P19Rik, Ibrdc2, Pir2}, Tbk1 (TANK-binding kinase 1) [NCBI Gene 56480] {aka 1200008B05Rik}, Vhl (von Hippel-Lindau tumor suppressor) [NCBI Gene 22346] {aka Vhlh, pVHL}, Actb (actin, beta) [NCBI Gene 11461] {aka Actx, E430023M04Rik, beta-actin}, Mul1 (mitochondrial ubiquitin ligase activator of NFKB 1) [NCBI Gene 68350] {aka 0610009K11Rik, Gide, Tnrip-1}, Trim21 (tripartite motif-containing 21) [NCBI Gene 20821] {aka Ro52, Ssa1}, Trim25 (tripartite motif-containing 25) [NCBI Gene 217069] {aka EFP, Zfp147}, Tnfaip2 (tumor necrosis factor, alpha-induced protein 2) [NCBI Gene 21928] {aka B94, Exoc3l3, M-sec, Tnfip2, tnfb94}, Atad3a (ATPase family, AAA domain containing 3A) [NCBI Gene 108888] {aka 2400004H09Rik, Atad3, Tob3, mKIAA1273}, Gpt (glutamic pyruvic transaminase, soluble) [NCBI Gene 76282] {aka 1300007J06Rik, 2310022B03Rik, ALT, ALT1, Gpt-1, Gpt1}, Trim72 (tripartite motif-containing 72) [NCBI Gene 434246] {aka MG53}, Il1b (interleukin 1 beta) [NCBI Gene 16176] {aka IL-1beta, Il-1b}, Irf3 (interferon regulatory factor 3) [NCBI Gene 54131] {aka C920001K05Rik, IRF-3}, MUL1 (mitochondrial E3 ubiquitin protein ligase 1) [NCBI Gene 79594] {aka C1orf166, GIDE, MAPL, MULAN, RNF218}, Tnf (tumor necrosis factor) [NCBI Gene 21926] {aka DIF, TNF-a, TNF-alpha, TNFSF2, TNFalpha, Tnfa}, Dntt (deoxynucleotidyltransferase, terminal) [NCBI Gene 21673] {aka Tdt}, IFIH1 (interferon induced with helicase C domain 1) [NCBI Gene 64135] {aka AGS7, Hlcd, IDDM19, IMD95, MDA-5, MDA5}, Ccl8 (C-C motif chemokine ligand 8) [NCBI Gene 20307] {aka 1810063B20Rik, HC14, MCP-2, Mcp2, Scya8}, Ocln (occludin) [NCBI Gene 18260] {aka Ocl}, TBK1 (TANK binding kinase 1) [NCBI Gene 29110] {aka AIARV, FTDALS4, IIAE8, NAK, T2K}, MAVS (mitochondrial antiviral signaling protein) [NCBI Gene 57506] {aka CARDIF, IPS-1, IPS1, VISA}, Rela (Rela proto-oncogene, NFKB subunit) [NCBI Gene 19697] {aka p65, p65 NF-kappa B, p65 NFkB}, NFKB1 (nuclear factor kappa B subunit 1) [NCBI Gene 4790] {aka CVID12, EBP-1, KBF1, NF-kB, NF-kB1, NF-kappa-B1}, Il6ra (interleukin 6 receptor, alpha) [NCBI Gene 16194] {aka CD126, IL-6R, IL-6R-alpha, IL-6RA, Il6r}, Tab2 (TGF-beta activated kinase 1/MAP3K7 binding protein 2) [NCBI Gene 68652] {aka 1110030N06Rik, A530078N03Rik, Map3k7ip2, mKIAA0733}, Pink1 (PTEN induced putative kinase 1) [NCBI Gene 68943] {aka 1190006F07Rik, BRPK, mFLJ00387}, Myc (Myc proto-oncogene, bHLH transcription factor) [NCBI Gene 17869] {aka Myc2, Niard, Nird, bHLHe39}, Mettl3 (methyltransferase 3, N6-adenosine-methyltransferase complex catalytic subunit) [NCBI Gene 56335] {aka 2310024F18Rik, M6A, Spo8}, Renbp (renin binding protein) [NCBI Gene 19703] {aka Age, Rnbp}, Rbfox3 (RNA binding protein, fox-1 homolog (C. elegans) 3) [NCBI Gene 52897] {aka Fox-3, Hrnbp3, NeuN, Neuna60}, Trat1 (T cell receptor associated transmembrane adaptor 1) [NCBI Gene 77647] {aka C030046M14Rik, Tcrim, Trim}, Fcr (Fc receptor) [NCBI Gene 109615], Ifih1 (interferon induced with helicase C domain 1) [NCBI Gene 71586] {aka 9130009C22Rik, Helicard, Hlcd, MDA5, RLR-2}, Usp8 (ubiquitin specific peptidase 8) [NCBI Gene 84092] {aka Ubpy, mKIAA0055}, Trim45 (tripartite motif-containing 45) [NCBI Gene 229644] {aka 4921530N01Rik}, Cybb (cytochrome b-245, beta polypeptide) [NCBI Gene 13058] {aka CGD91-phox, Cgd, Cyd, Nox2, gp91-1, gp91phox}, Trim8 (tripartite motif-containing 8) [NCBI Gene 93679] {aka GERP, Rnf27}, Trim47 (tripartite motif-containing 47) [NCBI Gene 217333] {aka 2210023F24Rik}, Il6 (interleukin 6) [NCBI Gene 16193] {aka Il-6}, Tjp1 (tight junction protein 1) [NCBI Gene 21872] {aka ZO1}, Pkm (pyruvate kinase, muscle) [NCBI Gene 18746] {aka Pk-2, Pk-3, Pk3, Pkm2}, Hif1a (hypoxia inducible factor 1, alpha subunit) [NCBI Gene 15251] {aka HIF-1-alpha, HIF1-alpha, HIF1alpha, MOP1, bHLHe78}, Dhx58 (DExH-box helicase 58) [NCBI Gene 80861] {aka B430001I08Rik, D11Lgp2e, LPG2, Lgp2, RLR-3}, MYC (MYC proto-oncogene, bHLH transcription factor) [NCBI Gene 4609] {aka MRTL, MYCC, bHLHe39, c-Myc}
- **Diseases:** CNS diseases (MESH:D002493), mitochondrial dysfunction (MESH:D028361), I/R (MESH:D015427), ischemia (MESH:D007511), neurotoxic (MESH:D020258), Neuroinflammation (MESH:D000090862), toxicity (MESH:D064420), tumorigenesis (MESH:D063646), obesity (MESH:D009765), Infarct (MESH:D007238), experimental autoimmune encephalomyelitis (MESH:D004681), Ischemic Brain Injury (MESH:D001930), subarachnoid hemorrhage (MESH:D013345), Ischemic stroke (MESH:D002544), hemorrhage (MESH:D006470), /R. (MESH:C580424), cerebral ischemic stroke (MESH:D020521), brain ischemic (MESH:D020520), MCAO (MESH:D020244), apoptosis (MESH:D065703), inflammation (MESH:D007249), TBI (MESH:D000070642), neuronal damage (MESH:D009410), BBB damage (MESH:C536830), coma (MESH:D003128), cerebral ischemic injury (MESH:D017202), brain damage (MESH:D001925), Alzheimer's disease (MESH:D000544), hypoxic (MESH:D002534), calcium (MESH:D002128), Neurological deficits (MESH:D009461), brain edema (MESH:D001929), tissue damage (MESH:D017695), OGD (MESH:C536050), astrogliosis (MESH:D005911), neurological damage (MESH:D020196), glioma (MESH:D005910), metabolic disorders (MESH:D008659), cerebral ischemia (MESH:D002545), cerebrovascular disease (MESH:D002561), myocardial infarction (MESH:D009203), atrial fibrillation (MESH:D001281)
- **Chemicals:** SDD (MESH:C003361), d-mannitol (MESH:D008353), trichloroacetic acid (MESH:D014238), glycerol (MESH:D005990), EDTA (MESH:D004492), TRIzol (MESH:C411644), PLGA (MESH:D000077182), nylon (MESH:D009757), urea nitrogen (MESH:C530477), MgCl2 (MESH:D015636), SDS (MESH:D012967), bromophenol blue (MESH:D001978), 4',6-diamidino-2-phenylindole (MESH:C007293), eosin (MESH:D004801), PFA (MESH:C003043), l-glutamine (MESH:D005973), Lipofectamine 2000 (MESH:C086724), KCl (MESH:D011189), deoxyuridine triphosphate (MESH:C027078), Percoll (MESH:C016039), Oxygen (MESH:D010100), PVA (MESH:D011142), MDA (MESH:D008315), agarose (MESH:D012685), DiO (-), IP (MESH:C041508), PVDF (MESH:C024865), silicone (MESH:D012828), 2',7'-dichlorodihydrofluorescein diacetate (MESH:C110400), N2 (MESH:D009584), glucose (MESH:D005947), polyacrylamide (MESH:C016679), hematoxylin (MESH:D006416), CO2 (MESH:D002245), sucrose (MESH:D013395), EB (MESH:D005070), PAMAM (MESH:C531249), H&amp;E (MESH:D006371), DCM (MESH:D008752), CHX (MESH:D003513), ROS (MESH:D017382), DCFH-DA (MESH:C029569), CRE (MESH:D003404), isoflurane (MESH:D007530)
- **Species:** Adeno-associated virus (species) [taxon 272636], Lyssavirus rabies (species) [taxon 11292], Homo sapiens (human, species) [taxon 9606], Mus musculus (house mouse, species) [taxon 10090]
- **Mutations:** C31A, H33W, A to C, lysine residues 23
- **Cell lines:** HEK293T — Homo sapiens (Human), Transformed cell line (CVCL_0063), tMCAO — Homo sapiens (Human), EBV-related Burkitt lymphoma, Cancer cell line (CVCL_W860)

## Full text

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## Figures

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## References

60 references — full list in the complete paper: https://tomesphere.com/paper/PMC12992933/full.md

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Source: https://tomesphere.com/paper/PMC12992933