Affinage

LARP4

La-related protein 4 · UniProt Q71RC2

Length
724 aa
Mass
80.6 kDa
Annotated
2026-06-10
27 papers in source corpus 15 papers cited in narrative 16 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

LARP4 is a cytoplasmic RNA-binding protein that protects mRNA poly(A) tails from deadenylation and tunes the stability and translation of specific mRNA subsets (PMID:28895529, PMID:32744499). It binds poly(A) RNA and poly(A)-binding protein (PABPC1) — engaging the PABP MLLE domain through its PAM2 motif — and its RNA-binding module, sensitive to poly(A) 3' termini, stabilizes PABP on tails to oppose deadenylation throughout mRNA lifespan, with the greatest effect on short tails of 30–75 nucleotides (PMID:28895529, PMID:32744499, PMID:33522422). A second, PABP-independent activity is mediated by its conserved region-2 (CR2), which directly binds the ribosome-associated protein RACK1 at propellers 5–6; this interaction is required for LARP4 to stabilize and promote the translational efficiency of ARE-containing mRNAs (PMID:39898547). Through these activities LARP4 supports translation of nuclear-encoded mitochondrial and oxidative phosphorylation mRNAs and respiratory chain function (PMID:38164626, PMID:40696044). LARP4 also acts at the cytoskeleton, binding the force-exposed cryptic site in the mechanosensing R21 domain of Filamin A via a region around residue F277 — an interaction resolved at atomic resolution that overlaps the integrin β-tail site — and this LARP4–FLNA interaction restrains cell migration and invasion (PMID:27615744, PMID:37169020, PMID:40466905). LARP4 abundance is itself controlled post-transcriptionally: an AU-rich element in its 3'UTR makes it a target of the TNF-α–tristetraprolin axis (PMID:26644407), and a translation-dependent codon-tRNA matching determinant in its coding region sets its expression level (PMID:28895529). In T cells, LARP4 governs activation-dependent mRNA stabilization, quiescence exit, and exhaustion, with its loss restoring mitochondrial fitness and anti-tumor effector persistence (PMID:32735645, PMID:40696044, PMID:41102557).

Mechanistic history

Synthesis pass · year-by-year structured walk · 15 steps
  1. 2015 High

    Established how LARP4 levels are themselves regulated, showing the RNA-stability machinery feeds back onto the regulator.

    Evidence β-globin reporter stability assay, RNA co-IP, TTP knockout cells, and TNF-α stimulation time-course

    PMID:26644407

    Open questions at the time
    • Does not address LARP4's own molecular function on target mRNAs
    • Physiological consequence of the transient TNF-α-induced LARP4 dip not defined
  2. 2017 High

    Defined LARP4's core biochemical activity: binding poly(A) and PABP to lengthen and stabilize mRNA poly(A) tails, answering what LARP4 does to mRNA.

    Evidence Genetic knockout, overexpression, PAT-seq, and domain mutagenesis with in-cell assays

    PMID:28895529

    Open questions at the time
    • Transcriptome-wide kinetics and tail-length dependence not yet resolved
    • Translation-level consequences not addressed
  3. 2017 Medium

    Showed LARP4 expression is set by codon-tRNA matching, identifying a translation-dependent coding-region instability determinant.

    Evidence Synonymous codon substitution panel and limiting-tRNA overexpression with mRNA level measurement

    PMID:28895529

    Open questions at the time
    • Mechanistic link to ribosome elongation/co-translational decay not detailed
    • In vivo relevance of the CRD untested
  4. 2016 Medium

    Connected LARP4's biochemistry to a cellular phenotype, identifying it as an inhibitor of cancer cell migration and invasion.

    Evidence RNAi depletion, overexpression, transwell and 3D Matrigel invasion assays, and Co-IP of PABP with a cancer truncation mutant

    PMID:27615744

    Open questions at the time
    • Molecular mechanism linking RNA activity to migration not yet defined here
    • Single-lab phenotype
  5. 2020 High

    Extended the deadenylation-protection model transcriptome-wide and pinpointed short poly(A) tails as the site of greatest LARP4 impact.

    Evidence Single-molecule PAT-seq in LARP4 knockout cells with time-course decay analysis

    PMID:32744499

    Open questions at the time
    • Does not identify which specific deadenylase is opposed
    • Selectivity for particular mRNA classes not resolved
  6. 2020 Medium

    Demonstrated a physiological role for LARP4-mediated mRNA stabilization in T cell activation.

    Evidence BruChase-Seq nascent mRNA stability profiling and cytokine secretion assays in Larp4 knockout mice

    PMID:32735645

    Open questions at the time
    • Direct binding of LARP4 to Nfkb1 mRNA not shown
    • Single lab
  7. 2021 Medium

    Consolidated the PAM2-MLLE interaction framework, formalizing how LARP4 docks onto PABP to stabilize it on poly(A) tails.

    Evidence Mechanistic review synthesizing prior biochemical PAM2-MLLE binding data

    PMID:33522422

    Open questions at the time
    • Review consolidating prior work rather than new experiments
    • Functional distinction from LARP1 not resolved
  8. 2023 Medium

    Identified a distinct cytoskeletal function, showing LARP4 binds the force-exposed R21 domain of Filamin A to regulate migration.

    Evidence Reciprocal in vivo/in vitro Co-IP, FRAP, proximity ligation, F277A mutagenesis, and migration rescue assays

    PMID:37169020

    Open questions at the time
    • Structural basis of the interaction not yet resolved here
    • Relationship between RNA-binding and FLNA-binding functions unclear
  9. 2024 High

    Resolved how LARP4 selectively promotes translation, mapping a CR2-RACK1 interaction that is separable from PABP binding.

    Evidence Yeast two-hybrid mapping, in vitro binding, AlphaFold2-Multimer, CR2 mutagenesis, polysome profiling, and luciferase reporters

    PMID:39898547

    Open questions at the time
    • How RACK1 recruitment selects ARE-mRNAs mechanistically not fully defined
    • Structural validation of CR2-RACK1 contact beyond prediction limited
  10. 2024 Medium

    Linked LARP4 to mitochondrial biogenesis by showing it binds and supports expression of nuclear-encoded mitochondrial mRNAs.

    Evidence CLIP-seq target identification, quantitative proteomics after depletion, mitochondrial function assays, and re-expression rescue

    PMID:38164626

    Open questions at the time
    • Whether the effect is via tail protection or CR2-RACK1 translation not dissected
    • Single lab
  11. 2024 Medium

    Showed LARP4 is hijacked by PEDV coronavirus, with cytoplasmic LARP4 and PABPC1 enhancing viral mRNA translation.

    Evidence Subcellular fractionation, knockdown, reporter assays, and rabbit reticulocyte lysate in vitro translation with purified proteins

    PMID:39182469

    Open questions at the time
    • Mechanism of CRM1-independent shuttling not defined
    • Generality across other viruses untested
  12. 2024 Medium

    Identified cooperation with the cytoplasmic poly(A) polymerase TENT5C in protecting globin mRNA tails during erythropoiesis.

    Evidence Co-AP/MS proteomics, poly(A) tail sequencing, LARP4/5 depletion, and TENT5C catalytic mutant mice (preprint)

    PMID:bio_10.1101_2024.11.14.623596

    Open questions at the time
    • Preprint not yet peer-reviewed
    • Stoichiometry and timing of the transient TENT5C association undefined
  13. 2025 High

    Determined the atomic structure of the LARP4-FLNA R21 complex and showed LARP4 competes with integrin tails for the same site.

    Evidence X-ray crystallography of FLNA R21 with LARP4 peptide, mutagenesis, in vitro competition, and migration assays

    PMID:40466905

    Open questions at the time
    • Functional consequence of integrin competition in vivo not established
    • How N275S alters membrane localization independent of FLNA unexplained
  14. 2025 High

    Established LARP4 as a driver of T cell exhaustion through OXPHOS mRNA hypertranslation, defining a targetable node for anti-tumor immunity.

    Evidence Conditional Larp4 knockout in T cells, translatome profiling, mitochondrial assays, in vivo tumor models, and CAR-T functional assays

    PMID:40696044

    Open questions at the time
    • Upstream signals controlling LARP4 activity in exhausted T cells not defined
    • Whether CR2-RACK1 or tail-protection mediates OXPHOS selectivity not dissected
  15. 2025 High

    Showed LARP4 controls naive T cell quiescence exit and differentiation, and demonstrated therapeutic inhibition with a peptide.

    Evidence Conditional knockout mouse, mRNA stability analysis, differentiation assays, and a peptide inhibitor (LIPEP) in autoimmune/allergy models

    PMID:41102557

    Open questions at the time
    • Molecular target/mechanism of the LIPEP peptide not detailed
    • Specific quiescence-controlling mRNAs not fully enumerated

Open questions

Synthesis pass · forward-looking unresolved questions
  • How LARP4's separable activities — poly(A)/PABP tail protection, CR2-RACK1 translational enhancement, and FLNA-mediated cytoskeletal regulation — are coordinated and selectively deployed across mRNA classes and cell contexts remains unresolved.
  • No unified model integrating RNA and cytoskeletal functions
  • Identity of the specific deadenylase(s) opposed not established
  • Determinants of mRNA-subset selectivity (ARE, OXPHOS, mitochondrial) not mechanistically defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 4 GO:0045182 translation regulator activity 3 GO:0098772 molecular function regulator activity 3 GO:0008092 cytoskeletal protein binding 2
Localization
GO:0005829 cytosol 2 GO:0005840 ribosome 1
Pathway
R-HSA-168256 Immune System 3 R-HSA-8953854 Metabolism of RNA 3 R-HSA-392499 Metabolism of proteins 2

Evidence

Reading pass · 16 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2017 LARP4 binds poly(A) RNA and poly(A)-binding protein (PABP), and its PABP-interaction domain and RNA-binding module are required for net lengthening of poly(A) tails (PATs) of heterologous mRNAs including ribosomal protein (RP) mRNAs, with concomitant mRNA stabilization. Genetic deletion of LARP4 decreases PAT length and RP mRNA stability. The RNA-binding module is sensitive to poly(A) 3'-termini, consistent with protection from deadenylation. Genetic knockout, overexpression, PAT-seq, domain mutagenesis, in-cell assays eLife High 28895529
2015 LARP4 mRNA 3'UTR contains a conserved AU-rich element (ARE) that destabilizes mRNA. Tristetraprolin (TTP) binds LARP4 mRNA in vivo and decreases cellular LARP4 levels; TTP knockout cells accumulate higher LARP4. TNF-α stimulation induces a TTP pulse that causes a transient decrease in LARP4 mRNA and protein, establishing LARP4 as a target of TNF-α–TTP post-transcriptional regulation. β-globin reporter stability assay, RNA co-immunoprecipitation, TTP gene knockout mouse cells, TNF-α stimulation Molecular and Cellular Biology High 26644407
2020 Single-molecule PAT-seq (SM-PAT-seq) transcriptome-wide analysis in LARP4 knockout versus control cells shows LARP4 opposes deadenylation throughout mRNA lifespan, with greatest impact at short poly(A) tails of 30–75 nucleotides. Accelerated deadenylation in KO cells at PATs <75 nt is consistent with greater PABP dissociation in the absence of LARP4. SM-PAT-seq (single-molecule nucleotide-resolution transcriptome-wide poly(A) tail sequencing), LARP4 knockout cells, time-course PAT decay analysis eLife High 32744499
2016 LARP4 depletion in PC3 and MDA-MB-231 cancer cells increases cell migration, invasion, and invasive protrusions in 3D Matrigel. Overexpression reduces cell elongation. A cancer-associated truncation mutant shows enhanced interaction with PABP and enhanced effects on cell morphology, establishing LARP4 as an inhibitor of cancer cell migration and invasion. RNAi depletion, overexpression, transwell migration/invasion assay, 3D Matrigel, Co-immunoprecipitation of PABP with truncation mutant Cytoskeleton (Hoboken, N.J.) Medium 27615744
2020 LARP4 knockout in mice destabilizes Nfκb1 mRNAs in CD4+ T cells and reduces secretion of IL-2 and IFN-γ upon T cell activation, placing LARP4 as a regulator of T cell activation-dependent mRNA stabilization. BruChase-Seq (transcriptome-wide nascent mRNA stability), Larp4 knockout mouse, cytokine secretion assay Nucleic Acids Research Medium 32735645
2021 LARP4 directly binds poly(A) and PABP (PABPC1), contains a PAM2 motif that interacts with the MLLE domain of PABP, and opposes deadenylation by stabilizing PABP on mRNA poly(A) tails. LARP1 and LARP4 are described as sharing these activities to protect mRNA 3' poly(A) tails from deadenylases. Review/mechanistic synthesis of prior biochemical data; PAM2-MLLE interaction established by prior in vitro binding assays referenced therein RNA Biology Medium 33522422
2023 LARP4 interacts with the mechanosensing immunoglobulin-like repeat 21 (R21) domain of Filamin A (FLNA) through a force-exposed cryptic binding site. The LARP4 region responsible maps to residues around position 277 (F277 in human). A F277A mutation disrupts FLNA binding. FRAP of GFP-LARP4 shows mutant LARP4 diffuses faster than WT. LARP4 knockdown increases cell migration speed, and expression of FLNA-binding-deficient LARP4 fails to rescue, establishing that LARP4–FLNA interaction regulates cell migration. Co-immunoprecipitation (in vivo and in vitro), FRAP, proximity ligation assay, site-directed mutagenesis, LARP4 knockdown, cell migration assay Frontiers in Cell and Developmental Biology Medium 37169020
2025 The crystal structure of FLNA R21 in complex with the LARP4 peptide (residues Ala269–Asn281) was determined by X-ray crystallography, showing LARP4 forms an extended β strand that binds the cleft formed by β strands C and D of FLNA R21. The LARP4-binding site overlaps with the integrin β tail-binding region, and in vitro assays show LARP4 competes with integrin β7 tails for FLNA R21 binding. Cancer-associated A279Cfs*2 and experimental F277A mutations disrupt binding; N275S alters membrane localization without affecting FLNA binding. X-ray crystallography, protein-protein interaction assays, site-directed mutagenesis, cell migration assay, in vitro competition assay Journal of Molecular Biology High 40466905
2024 LARP4's conserved region-2 (CR2; positions 615–625) directly binds RACK1 (a ribosome-associated protein) at RACK1 propellers 5 and 6 (residues 200–317), as established by yeast two-hybrid mapping, in vitro binding, AlphaFold2-Multimer prediction, and confirmed by CR2 mutations that abolish RACK1 and ribosome association. CR2 mutations reduce LARP4's ability to stabilize ARE-containing mRNAs and impair LARP4-mediated translational efficiency of ARE-mRNAs, while PABP association is less affected, indicating independent interactions. Yeast two-hybrid domain mapping, in vitro binding assay, AlphaFold2-Multimer structural prediction, site-directed mutagenesis, polysome profiling, luciferase reporter assay, Co-immunoprecipitation Nucleic Acids Research High 39898547
2024 LARP4 preprint (same study as PMID 39898547): CR2 of LARP4 (positions 615–625) directly binds RACK1 region 200–317; CR2 mutations abolish RACK1/ribosome association without equally affecting PABP; LARP4 promotes translational efficiency of ARE-containing mRNAs via this CR2–RACK1 interaction. Yeast two-hybrid, in vitro binding, mutagenesis, polysome profiling, nanoLuc reporter assay bioRxivpreprint Medium 39554137
2024 LARP4 binds nuclear-encoded mitochondrial mRNAs (NEMmRNAs), particularly those encoding respiratory chain complex proteins (RCCPs) and mitochondrial ribosome proteins (MRPs). LARP4 depletion significantly reduces RCCP and MRP protein levels by quantitative proteomics and reduces mitochondrial function; LARP4 re-expression rescues mitochondrial respiratory function. CLIP-seq (systematic RBP-RNA target analysis across 150 RBPs), quantitative proteomics after LARP4 depletion, mitochondrial function assays, rescue by LARP4 re-expression RNA (New York, N.Y.) Medium 38164626
2024 PEDV coronavirus infection induces nuclear-to-cytoplasmic shuttling of LARP4 via a CRM1-independent pathway. Cytoplasmic LARP4 binds the 3'UTR of PEDV mRNA with assistance from PABPC1 to facilitate viral mRNA translation. LARP4 knockdown reduces PABPC1-induced 3'UTR translation activity. Purified prokaryotic LARP4 and PABPC1 together enhance PEDV mRNA translation in a rabbit reticulocyte lysate (RRL) system. Subcellular fractionation/localization, LARP4 knockdown, RRL in vitro translation assay, reporter assays Veterinary Microbiology Medium 39182469
2025 LARP4 drives hypertranslation in exhausted/dysfunctional intratumoral T cells by selectively enhancing translation of nuclear-encoded oxidative phosphorylation (OXPHOS) mRNAs, disrupting OXPHOS subunit balance and causing mitochondrial dysfunction. Knockout of Larp4 in tumor-specific CD8+ T cells reduces hypertranslation, restores mitochondrial function, mitigates exhaustion, and enhances anti-tumor effector persistence. LARP4 knockdown in CAR-T cells prevents terminal exhaustion. Conditional Larp4 knockout in T cells, translatome profiling, mitochondrial function assays, in vivo tumor models, CAR-T cell functional assays Nature Immunology High 40696044
2025 Conditional knockout of LARP4 in naive CD4+ T cells enhances quiescence and dampens quiescence exit by altering stability of mRNAs important for T cell activation, impairing differentiation into helper T cell subsets. A peptide inhibitor of LARP4 (LIPEP) mimics LARP4 deficiency and ameliorates autoimmune and allergic responses in mouse models. Conditional knockout mouse, mRNA stability analysis, T cell differentiation assays, peptide inhibitor in vivo mouse disease models Nature Biomedical Engineering High 41102557
2024 LARP4 cooperates with TENT5C cytoplasmic poly(A) polymerase in erythropoiesis: LARP4/5 depletion leads to downregulation and poly(A) tail shortening of globin mRNAs. Proteomic experiments revealed a transient but specific association of TENT5C with LARP4/5. Lack of TENT5C catalytic activity is accompanied by compensatory upregulation of LARP4/5, indicating functional redundancy in protecting globin mRNA poly(A) tails. Proteomics (Co-AP/MS), poly(A) tail length sequencing, LARP4/5 depletion, TENT5C catalytic mutant knock-in mice bioRxivpreprint Medium bio_10.1101_2024.11.14.623596
2017 The LARP4 mRNA contains a translation-dependent coding region determinant (CRD) of instability comprising <10% of codons; synonymous substitutions accommodating tRNA dynamics cause >20-fold variation in LARP4 mRNA levels. Overexpression of the most limiting tRNA increases LARP4 protein levels, indicating LARP4 expression is controlled by codon-tRNA matching during translation. Synonymous codon substitution, tRNA overexpression, mRNA level measurement eLife Medium 28895529

Source papers

Stage 0 corpus · 27 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 Circular RNA_LARP4 inhibits cell proliferation and invasion of gastric cancer by sponging miR-424-5p and regulating LATS1 expression. Molecular cancer 448 28893265
2017 LARP4 mRNA codon-tRNA match contributes to LARP4 activity for ribosomal protein mRNA poly(A) tail length protection. eLife 44 28895529
2020 Up-regulation of circ_LARP4 suppresses cell proliferation and migration in ovarian cancer by regulating miR-513b-5p/LARP4 axis. Cancer cell international 43 31911757
2019 Circular RNA LARP4 correlates with decreased Enneking stage, better histological response, and prolonged survival profiles, and it elevates chemosensitivity to cisplatin and doxorubicin via sponging microRNA-424 in osteosarcoma. Journal of clinical laboratory analysis 41 31642110
2016 The RNA-binding protein LARP4 regulates cancer cell migration and invasion. Cytoskeleton (Hoboken, N.J.) 36 27615744
2021 LARP1 and LARP4: up close with PABP for mRNA 3' poly(A) protection and stabilization. RNA biology 33 33522422
2020 Circular RNA_LARP4 Sponges miR-1323 and Hampers Progression of Esophageal Squamous Cell Carcinoma Through Modulating PTEN/PI3K/AKT Pathway. Digestive diseases and sciences 33 31897898
2020 Single molecule poly(A) tail-seq shows LARP4 opposes deadenylation throughout mRNA lifespan with most impact on short tails. eLife 31 32744499
2020 Circ_LARP4 regulates high glucose-induced cell proliferation, apoptosis, and fibrosis in mouse mesangial cells. Gene 19 32891769
2020 Circular RNA_LARP4 inhibits cell migration and invasion of prostate cancer by targeting FOXO3A. European review for medical and pharmacological sciences 17 32495863
2020 Transcriptome-wide stability analysis uncovers LARP4-mediated NFκB1 mRNA stabilization during T cell activation. Nucleic acids research 14 32735645
2024 LARP4 is an RNA-binding protein that binds nuclear-encoded mitochondrial mRNAs to promote mitochondrial function. RNA (New York, N.Y.) 13 38164626
2015 LARP4 Is Regulated by Tumor Necrosis Factor Alpha in a Tristetraprolin-Dependent Manner. Molecular and cellular biology 12 26644407
2023 Genome Doubling Shapes High-Grade Transformation and Novel EWSR1::LARP4 Fusion Shows SOX10 Immunostaining in Hyalinizing Clear Cell Carcinoma of Salivary Gland. Laboratory investigation; a journal of technical methods and pathology 11 37479138
2025 The short conserved region-2 of LARP4 interacts with ribosome-associated RACK1 and promotes translation. Nucleic acids research 10 39898547
2020 Circular RNA_LARP4 inhibits the progression of non-small-cell lung cancer by regulating the expression of SMAD7. European review for medical and pharmacological sciences 10 32141555
2025 LARP4-mediated hypertranslation drives T cell dysfunction in tumors. Nature immunology 8 40696044
2023 Interaction of LARP4 to filamin A mechanosensing domain regulates cell migrations. Frontiers in cell and developmental biology 8 37169020
2019 Circular RNA_LARP4 inhibits cell proliferation and invasion of nasopharyngeal carcinoma by repressing ROCK1. European review for medical and pharmacological sciences 8 31799660
2022 CircBNC2 affects epithelial ovarian cancer progression through the miR-223-3p/ LARP4 axis. Anti-cancer drugs 7 36730544
2024 Cellular RNA-binding proteins LARP4 and PABPC1 synergistically facilitate viral translation of coronavirus PEDV. Veterinary microbiology 4 39182469
2020 Circular RNA_LARP4 inhibits cell proliferation and invasion of nasopharyngeal carcinoma by repressing ROCK1. European review for medical and pharmacological sciences 3 33378005
2025 Inhibition of LARP4-mediated quiescence exit of naive CD4+ T cells ameliorates autoimmune and allergic diseases. Nature biomedical engineering 2 41102557
2025 Structural Basis of the LARP4-Filamin A Interaction and Competition with Integrin β7 Tails. Journal of molecular biology 0 40466905
2024 Biological functions of Circular RNA_LARP4/ Upstream frameshift 1 in development of gastric cancer. Cellular and molecular biology (Noisy-le-Grand, France) 0 38678610
2024 The short conserved region-2 of LARP4 interacts with ribosome-associated RACK1 and promotes translation. bioRxiv : the preprint server for biology 0 39554137
2022 [Overexpression of circ_LARP4 inhibits the proliferation and migration of MCF-7 human breast cancer cells and its mechanism]. Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology 0 35365990

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