{"gene":"LIMA1","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2003,"finding":"EPLIN directly binds actin filaments at two distinct binding sites, inhibits actin filament depolymerization, cross-links filaments into bundles, and inhibits branching nucleation by the Arp2/3 complex via side-binding activity; it does not affect spontaneous polymerization kinetics or barbed-end elongation.","method":"In vitro biochemical assays with purified recombinant EPLIN (depolymerization assay, bundling/cross-linking assay, Arp2/3-mediated nucleation assay, actin polymerization kinetics)","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 — multiple in vitro reconstitution assays with purified protein, foundational mechanistic paper with high citation count","pmids":["12566430"],"is_preprint":false},{"year":1999,"finding":"EPLIN is a cytoskeletal protein with a single central LIM domain that localizes to filamentous actin and suppresses cell proliferation when overexpressed; two isoforms (alpha, 600 aa; beta, 759 aa) are generated from a single gene.","method":"Subcellular localization by immunofluorescence; overexpression in epithelial cells with proliferation assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2–3 — original discovery paper with direct localization and functional assay, single lab","pmids":["10618726"],"is_preprint":false},{"year":2002,"finding":"The N-terminal region of EPLIN is required for both its localization to the actin cytoskeleton and suppression of anchorage-independent growth; loss of cytoskeletal localization (as in Ras-transformed cells) abolishes the tumor-suppressive function.","method":"Retroviral transduction of truncated EPLIN constructs in NIH3T3 cells; soft-agar colony formation assay; immunofluorescence localization","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — domain-deletion mutagenesis with functional readout, single lab","pmids":["11950948"],"is_preprint":false},{"year":2007,"finding":"ERK phosphorylates EPLIN at Ser360, Ser602, and Ser692; phosphorylation of the C-terminal region reduces EPLIN's affinity for actin filaments. ERK-mediated phosphorylation drives redistribution of EPLIN from stress fibers to membrane ruffles and is required for PDGF-induced stress fiber disassembly, membrane ruffling, and cell migration.","method":"In vitro kinase assay with purified ERK and EPLIN; phospho-specific antibodies in intact cells; non-phosphorylatable mutant overexpression; wound healing and migration assays; PDGF stimulation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro kinase assay plus mutagenesis plus functional phenotype, single lab with multiple orthogonal methods","pmids":["17875928"],"is_preprint":false},{"year":2007,"finding":"EPLIN (LIMA1) couples with alpha-catenin and links the E-cadherin–catenin complex to F-actin at adherens junctions. EPLIN depletion disorganizes the circumferential actin adhesion belt, converting it to zipper-like junctions with radially arranged actin, without affecting non-junctional actin fibers.","method":"Co-immunoprecipitation of EPLIN with alpha-catenin; siRNA depletion in epithelial cells; immunofluorescence of actin and junctional markers","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus clean KD with specific morphological phenotype, high citation count, replicated in endothelial cells","pmids":["18093941"],"is_preprint":false},{"year":2009,"finding":"EPLIN localizes to the cleavage furrow during cytokinesis via association with contractile ring components myosin II and the septin Sept2; EPLIN depletion causes multinucleation due to inefficient accumulation of active myosin II (MRLC-S19), Sept2, RhoA, and Cdc42 at the furrow.","method":"Immunofluorescence localization during cytokinesis; Co-immunoprecipitation with myosin II and Sept2; siRNA depletion with multinucleation quantification","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2–3 — direct localization with functional consequence plus Co-IP, single lab","pmids":["19221476"],"is_preprint":false},{"year":2011,"finding":"Junctional tension is required to retain EPLIN at adherens junctions; lateral actin fiber forces inhibit EPLIN–AJ association. An alpha-catenin–EPLIN fusion promotes zonula adherens (ZA) formation but not punctate AJ formation, placing EPLIN as a mechanosensitive regulator downstream of tension at the ZA. Vinculin cooperates with EPLIN to maintain ZA integrity.","method":"Live imaging of EPLIN at junctions with mechanical perturbation; rescue experiments with alpha-catenin–EPLIN fusion construct; vinculin depletion combined with EPLIN depletion","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic and pharmacological perturbations with defined mechanosensitive phenotype, replicated concept from prior work","pmids":["21844208"],"is_preprint":false},{"year":2011,"finding":"EPLIN interacts directly with alpha-catenin and tethers the VE-cadherin–catenin complex to the actin cytoskeleton in endothelial cells; EPLIN depletion delocalizes vinculin from junctions and reduces pseudocapillary network formation in a Matrigel angiogenesis assay.","method":"Co-immunoprecipitation and GST pulldown of EPLIN with alpha-catenin; siRNA depletion; immunofluorescence; Matrigel tube formation assay; blebbistatin treatment","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — GST pulldown plus reciprocal Co-IP plus functional assay; extends epithelial finding to endothelial system","pmids":["22194609"],"is_preprint":false},{"year":2011,"finding":"EPLIN depletion during epithelial-mesenchymal transition in prostate cancer cells causes disassembly of adherens junctions, actin remodeling, and activation of beta-catenin signaling, establishing EPLIN as a negative regulator of EMT.","method":"siRNA depletion; immunofluorescence of junctional markers; beta-catenin reporter assay; quantitative proteomics in EMT model","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — multiple assays in experimental EMT model, single lab","pmids":["21625216"],"is_preprint":false},{"year":2012,"finding":"EGF promotes ERK1/2-dependent phosphorylation, ubiquitination, and proteasomal degradation of EPLIN; Ser362 and Ser604 are the critical ERK1/2 phosphorylation sites whose mutation confers resistance to EGF-induced EPLIN turnover.","method":"EGF stimulation of prostate cancer cells; ERK1/2 inhibitor treatment; phospho-site mutagenesis; ubiquitination assay; cycloheximide chase","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — site-directed mutagenesis plus ubiquitination assay plus pharmacological rescue, multiple orthogonal methods","pmids":["23188829"],"is_preprint":false},{"year":2013,"finding":"DNp73 drives loss of EPLIN expression, which de-represses IGF1R signaling and activates AKT/STAT3 to promote migration and invasion; EPLIN acts as a direct inhibitor of IGF1R-AKT/STAT3 activation downstream of the p73/DNp73 axis.","method":"Knockdown/overexpression of DNp73 and EPLIN; xenograft invasion/metastasis assay; signaling pathway analysis by Western blot; co-expression rescue experiments","journal":"Cancer cell","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro and in vivo epistasis with pathway readout, single lab","pmids":["24135282"],"is_preprint":false},{"year":2015,"finding":"API2-MALT1 fusion protein cleaves LIMA1 via MALT1 paracaspase activity; API2 mediates LIMA1 binding, and proteolysis generates an oncogenic LIM-domain-only fragment that promotes lymphomagenesis. Primary MALT lymphomas harboring API2-MALT1 uniquely show LIMA1 cleavage fragments.","method":"Co-immunoprecipitation; paracaspase cleavage assay with API2-MALT1 mutants; in vitro and in vivo oncogenicity assays; primary tumor immunoblot for cleavage products","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 — direct cleavage assay with active-site mutant controls, validated in primary patient tumors","pmids":["25569716"],"is_preprint":false},{"year":2015,"finding":"EPLIN functions upstream of Caveolin-1 in RasV12-transformed cells surrounded by normal cells, promoting apical extrusion; EPLIN regulates non-cell-autonomous myosin-II and PKA activation in transformed cells and affects filamin A accumulation in neighboring normal cells.","method":"siRNA depletion; mixed culture of normal and RasV12-transformed cells; live imaging of apical extrusion; epistasis experiments (EPLIN KD upstream of Cav-1 KD)","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis in defined cellular context with quantified extrusion phenotype","pmids":["25609711"],"is_preprint":false},{"year":2015,"finding":"PINCH-1 interacts with EPLIN at integrin adhesion sites in keratinocytes; EPLIN localization to focal adhesions is PINCH-1-dependent; EPLIN depletion severely attenuates keratinocyte spreading and migration on collagen and fibronectin independently of PINCH-1 levels.","method":"PINCH-1 interactome by mass spectrometry; co-immunoprecipitation; PINCH-1 conditional knockout in epidermis; EPLIN siRNA depletion; adhesion and migration assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1–2 — MS interactome plus in vivo KO plus in vitro functional assays, multiple orthogonal approaches","pmids":["25609703"],"is_preprint":false},{"year":2017,"finding":"p53 transcriptionally induces LIMA1 expression by binding two p53 response elements in the LIMA1 gene; LIMA1 mediates p53-dependent suppression of cancer cell invasion.","method":"ChIP-seq for p53 binding; microarray identification of LIMA1 as p53 target; nutlin-3a activation of endogenous p53; LIMA1 knockdown in p53 invasion-suppression assay","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP-seq with functional epistasis (KD partially reverses p53 effect), single lab","pmids":["28093207"],"is_preprint":false},{"year":2018,"finding":"LIMA1 is expressed in the small intestinal brush border membrane and bridges NPC1L1 (the cholesterol transporter) to a myosin Vb-containing transport complex, facilitating intestinal cholesterol uptake. Lima1-deficient mice show reduced cholesterol absorption and resistance to diet-induced hypercholesterolemia.","method":"Rare frameshift variant identification in family; Lima1 KO mouse model; brush border fractionation; co-immunoprecipitation of LIMA1 with NPC1L1 and myosin Vb; cholesterol absorption measurements","journal":"Science","confidence":"High","confidence_rationale":"Tier 1–2 — KO mouse plus Co-IP complex identification plus human genetic validation, high citation count","pmids":["29880681"],"is_preprint":false},{"year":2018,"finding":"Paxillin binds EPLIN specifically in RasV12-transformed cells surrounded by normal cells; paxillin, plectin, and EPLIN mutually influence their accumulation and cooperate to promote acetylated tubulin enrichment via paxillin-mediated suppression of HDAC6, facilitating apical extrusion.","method":"Co-immunoprecipitation of paxillin with EPLIN in mixed culture; siRNA depletion; immunofluorescence of acetylated tubulin and HDAC6 activity assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP in defined cellular context plus epistasis, single lab","pmids":["29391412"],"is_preprint":false},{"year":2010,"finding":"EPLIN-alpha transcription is regulated by the actin-MAL/MRTF-SRF signaling pathway; monomeric actin represses MAL-SRF-dependent EPLIN-alpha expression, while conditions that release MAL from G-actin induce EPLIN-alpha but not EPLIN-beta, revealing isoform-specific transcriptional control.","method":"Transcriptome analysis with actin-binding drugs; dominant-negative MAL overexpression; constitutively active actin mutants; MAL/SRF ChIP at EPLIN-alpha promoter; promoter-reporter assays","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus pharmacological and genetic perturbation of pathway, multiple complementary approaches","pmids":["20236507"],"is_preprint":false},{"year":2019,"finding":"EPLIN-alpha localizes to membrane protrusions and interacts with the Arp2/3 complex to terminate branched actin growth, while EPLIN-beta localizes to stress fibers and stabilizes them; FRAP shows lower EPLIN-beta turnover rate, consistent with a filament-stabilizing role distinct from EPLIN-alpha's protrusion-regulating function.","method":"Isoform-specific overexpression and depletion; FRAP of EPLIN-alpha vs. -beta; co-localization with Arp2/3; shear stress experiments in aortic vs. vena cava endothelial cells","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — FRAP plus isoform-specific functional assays plus multiple cellular contexts, multiple orthogonal methods","pmids":["31644899"],"is_preprint":false},{"year":2020,"finding":"EPLIN interacts with LUZP1 and together they restrict primary cilia formation; depleting either EPLIN or LUZP1 increases MyosinVa at the centrosome and promotes ciliogenesis. EPLIN and LUZP1 stabilize actin dynamics at least partly by mobilizing ARP2 to centrosomes.","method":"Proximity ligation/BioID interactome; siRNA depletion of EPLIN or LUZP1; cilia quantification; centrosome MyosinVa immunofluorescence; actin dynamics assays","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2 — BioID interaction plus KD phenotype with centrosome/cilia readout, single lab","pmids":["32496561"],"is_preprint":false},{"year":2021,"finding":"Rab40b interacts with Cullin5 via its SOCS domain and EPLIN is a binding partner and substrate for Rab40b-Cullin5-dependent localized ubiquitylation and degradation; loss of this ubiquitylation increases EPLIN levels, stabilizes focal adhesions, and reduces cell migration and invadopodia formation.","method":"Co-immunoprecipitation of Rab40b with Cullin5 and EPLIN; ubiquitylation assay; Rab40b-Cullin5 interaction mutants; EPLIN degradation rescue experiments; migration and invasion assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1–2 — direct ubiquitylation assay plus interaction mutant plus functional rescue, multiple orthogonal methods","pmids":["33999101"],"is_preprint":false},{"year":2022,"finding":"Lima1 expression is controlled by the naive pluripotency circuit in mouse embryonic stem cells and is required to suppress membrane blebbing and maintain proper mitochondrial energetics; forced Lima1 expression enables primed pluripotent cells to incorporate into pre-implantation embryos.","method":"Lima1 KO and overexpression in mouse ESCs; live imaging of membrane blebbing; mitochondrial respiration assay; chimera assay in pre-implantation embryos","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — KO with two distinct functional phenotypes plus rescue, single lab","pmids":["35105859"],"is_preprint":false},{"year":2022,"finding":"LIMA1 inhibits the Wnt/beta-catenin pathway in hepatocellular carcinoma by binding BMI1 and inducing its destabilization; loss of LIMA1 stabilizes BMI1 and activates beta-catenin signaling to promote HCC proliferation and metastasis.","method":"Co-immunoprecipitation of LIMA1 with BMI1; overexpression/knockdown of LIMA1; beta-catenin reporter assay; xenograft mouse model","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2–3 — Co-IP plus functional assay, single lab","pmids":["36497115"],"is_preprint":false},{"year":2023,"finding":"EPLIN-beta (but not EPLIN-alpha) is a novel substrate of ornithine decarboxylase antizyme 1 (Az1/OAZ1); Az1 degrades EPLIN-beta in a ubiquitination-independent, proteasome-mediated manner; Az1 absence elevates EPLIN-beta and causes enhanced cellular migration.","method":"Quantitative proteomics to identify Az1 substrates; co-immunoprecipitation of EPLIN-beta with Az1; ubiquitination assay (showing independence); proteasome inhibitor rescue; migration assay after Az1 KO","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 — proteomics identification plus Co-IP plus mechanistic ubiquitination assay, single lab","pmids":["37325974"],"is_preprint":false},{"year":2023,"finding":"MAD2 sequesters USP44 in the nucleus, preventing USP44 from binding and deubiquitinating LIMA1, leading to enhanced K48-linked ubiquitination and degradation of LIMA1 and consequent activation of IGF1R/PI3K/AKT signaling in cholangiocarcinoma.","method":"Co-immunoprecipitation of USP44 with LIMA1; ubiquitination assay (K48-linked); nuclear fractionation showing MAD2 sequestration of USP44; pathway activation by Western blot; PDTX model","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus K48-ubiquitination assay plus functional pathway readout, single lab","pmids":["37752233"],"is_preprint":false},{"year":2024,"finding":"RNF40, an E3 ubiquitin ligase, mediates ubiquitination and proteasomal degradation of LIMA1; the 1–166 aa fragment of LIMA1 is indispensable for the LIMA1–RNF40 interaction. RNF40-mediated LIMA1 degradation reduces cellular lipid content, which is reversed by LIMA1 overexpression.","method":"Co-immunoprecipitation of RNF40 with LIMA1; domain-mapping with truncation mutants; ubiquitination assay; proteasome inhibitor rescue; lipid content measurement","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP with domain mapping plus ubiquitination assay plus functional lipid readout, single lab","pmids":["38909032"],"is_preprint":false},{"year":2024,"finding":"Cytoplasmic p62 (SQSTM1) interacts with EPLIN via GST pulldown and enhances EPLIN protein stability; elevated EPLIN in ESCC promotes migration and invasion, and reducing EPLIN expression inhibits these phenotypes.","method":"GST pulldown of p62 with EPLIN; p62 knockdown/overexpression with localization control; EPLIN rescue after p62 KD; migration and invasion assays","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 3 — GST pulldown plus functional rescue, single lab","pmids":["38185251"],"is_preprint":false},{"year":2024,"finding":"LIMA1 O-GlcNAcylation at T662 (catalyzed by OGT, promoted by steatosis-induced HCF1/OGT upregulation) inhibits its ubiquitin-dependent degradation and enhances hepatocyte lipid deposition via activation of beta-catenin/FASn signaling; LIMA1-T662A mutant mice showed reduced steatosis, inflammation, and fibrosis.","method":"O-GlcNAc site mapping by mass spectrometry; site-directed mutagenesis (T662A); AAV-mediated liver-specific expression in LIMA1 HKO mice; beta-catenin/FASn pathway analysis by Western blot; OGT inhibitor studies","journal":"Advanced science","confidence":"High","confidence_rationale":"Tier 1–2 — PTM site identification by MS plus mutagenesis plus in vivo mouse model, multiple orthogonal methods","pmids":["39921472"],"is_preprint":false},{"year":2024,"finding":"LIMA1 interacts with PINK1 and inhibits PINK1-Parkin-mediated mitophagy in hepatic stellate cells; LIMA1 delivered via lipotoxic hepatocyte-derived small extracellular vesicles promotes HSC activation by blocking mitophagy.","method":"Molecular docking and database prediction; LIMA1 KD in LX2 cells; mt-keima lentivirus to detect mitophagy; sEV isolation and delivery assay; in vivo HFD mouse model","journal":"Cellular & molecular biology letters","confidence":"Low","confidence_rationale":"Tier 3–4 — interaction predicted by docking, functional KD data without direct biochemical LIMA1-PINK1 binding validation","pmids":["38822260"],"is_preprint":false},{"year":2024,"finding":"SEPT9 directly interacts with the LIM domain of EPLIN; this interaction regulates actin stress fiber and filopodia organization, focal adhesion size, and cell adhesion and migration in human fibroblasts. Increased EPLIN levels can partially rescue the low motility of SEPT9 KO cells.","method":"SEPT9 KO fibroblast cell line; co-expression and interaction assays; immunofluorescence of actin structures and focal adhesions; migration assays with rescue by EPLIN overexpression","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2–3 — KO with genetic rescue plus LIM domain interaction characterization, single lab","pmids":["38719752"],"is_preprint":false},{"year":2025,"finding":"IRBIT and LIMA1 form a complex with the brush border Cl-/HCO3- exchanger SLC26A3 (DRA); cAMP/ATP stimulation increases the association of LIMA1 with both IRBIT and DRA; LIMA1 knockdown selectively reduces cAMP plus ATP stimulation of DRA activity without affecting basal activity.","method":"Co-immunoprecipitation of DRA with IRBIT and LIMA1; LIMA1 siRNA knockdown; functional SLC26A3 transport assay with pharmacological stimulation; brush border fractionation","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus functional transport assay with KD, single lab","pmids":["40569378"],"is_preprint":false},{"year":2026,"finding":"BPNT1 recruits E3 ubiquitin ligase STUB1 to induce proteasomal degradation of LIMA1, promoting EMT and TNBC progression; re-expression of LIMA1 in BPNT1-overexpressing cells partially reverses EMT and malignant phenotypes.","method":"Co-immunoprecipitation of BPNT1 with STUB1 and LIMA1; ubiquitination/degradation assay; LIMA1 re-expression rescue; xenograft mouse model; in vitro invasion/migration assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus ubiquitination assay plus in vivo rescue, single lab","pmids":["41540000"],"is_preprint":false},{"year":2024,"finding":"EPLINα localizes to Rab21-positive recycling endosomes (in addition to actin ruffles) via its actin-binding activity; EPLINα interacts with Rab21 and supports beta1-integrin recycling and cell migration. Coronin 1C is an EPLIN-proximal protein at Rab21 endosomes in an EPLINα-dependent manner. High EPLINα-to-EPLINβ ratio correlates with mesenchymal phenotype in breast cancer.","method":"Isoform-specific localization by live imaging; BioID proximity proteomics; Co-localization of EPLINα with Rab21 and F-actin on endosomes; actin-binding mutant; integrin recycling assay","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 — BioID plus direct co-localization plus functional integrin recycling assay, single lab preprint","pmids":["bio_10.1101_2024.06.27.600789"],"is_preprint":true}],"current_model":"LIMA1/EPLIN is a dual-function actin-binding protein that (1) cross-links and stabilizes actin filaments while inhibiting Arp2/3-mediated branched nucleation, (2) links the cadherin–catenin complex to F-actin at adherens junctions in a mechanosensitive, tension-dependent manner, (3) undergoes ERK-mediated phosphorylation and RNF40/STUB1/Rab40b-Cullin5-mediated ubiquitin–proteasomal degradation that regulate its actin affinity and stability, (4) bridges NPC1L1 to a myosin Vb transport complex to facilitate intestinal cholesterol absorption, (5) is cleaved by the API2-MALT1 paracaspase to generate an oncogenic LIM-domain fragment, and (6) controls cytokinesis, ciliogenesis, integrin recycling, and mechanosensitive junction remodeling through isoform-specific interactions with alpha-catenin, PINCH-1, Rab21, LUZP1, and septins."},"narrative":{"teleology":[{"year":1999,"claim":"Establishing LIMA1 as a novel LIM-domain cytoskeletal protein with two isoforms answered whether the gene encoded a structural or signaling factor, placing it at actin filaments with growth-suppressive properties.","evidence":"Immunofluorescence localization to F-actin and overexpression proliferation assay in epithelial cells","pmids":["10618726"],"confidence":"Medium","gaps":["Mechanism of proliferation suppression unknown","No biochemical actin-binding data yet"]},{"year":2002,"claim":"Mapping the N-terminal region as essential for both actin localization and anchorage-independent growth suppression established that cytoskeletal targeting is required for LIMA1's tumor-suppressive function.","evidence":"Truncated EPLIN constructs in NIH3T3 cells with soft-agar colony formation and immunofluorescence","pmids":["11950948"],"confidence":"Medium","gaps":["Specific actin-binding domains not yet biochemically defined","No in vivo tumor model"]},{"year":2003,"claim":"Reconstitution with purified protein demonstrated that LIMA1 directly binds, bundles, and stabilizes actin filaments while inhibiting Arp2/3-mediated branching, defining its core biochemical activities.","evidence":"In vitro depolymerization, bundling, and Arp2/3 nucleation assays with purified recombinant EPLIN","pmids":["12566430"],"confidence":"High","gaps":["Relative contribution of the two actin-binding sites in cells unknown","No structural model of actin–EPLIN interface"]},{"year":2007,"claim":"Discovery that ERK phosphorylates LIMA1 at C-terminal serines to reduce actin affinity, redistribute LIMA1 to ruffles, and enable PDGF-induced migration revealed the first post-translational switch controlling LIMA1 function.","evidence":"In vitro ERK kinase assay, phospho-site mutagenesis, wound healing assay with PDGF stimulation","pmids":["17875928"],"confidence":"High","gaps":["No crystal structure of phosphorylated vs. unphosphorylated actin-binding domain","Whether other kinases target the same sites not tested"]},{"year":2007,"claim":"Identification of LIMA1 as the physical link between alpha-catenin and F-actin at adherens junctions resolved a long-standing question of how the cadherin–catenin complex engages the actin cytoskeleton.","evidence":"Reciprocal Co-IP of EPLIN with alpha-catenin; siRNA depletion converting circumferential actin belt to radial zipper junctions in epithelial cells","pmids":["18093941"],"confidence":"High","gaps":["Whether the interaction is direct or via additional adaptor proteins at endogenous stoichiometry","Mechanosensitivity not yet tested"]},{"year":2009,"claim":"Localization of LIMA1 to the cleavage furrow via myosin II and septin interactions, and multinucleation upon depletion, extended LIMA1 function beyond junctions to cytokinesis.","evidence":"Co-IP with myosin II and Sept2; siRNA depletion with multinucleation quantification","pmids":["19221476"],"confidence":"Medium","gaps":["Whether LIMA1 is required for contractile ring assembly or maintenance not distinguished","No live imaging of furrow dynamics after depletion"]},{"year":2010,"claim":"Demonstrating that MAL/MRTF–SRF signaling transcriptionally induces only EPLIN-alpha revealed isoform-specific transcriptional regulation linked to the cellular actin monomer/polymer balance.","evidence":"MAL/SRF ChIP at EPLIN-alpha promoter; dominant-negative MAL and actin-binding drugs","pmids":["20236507"],"confidence":"Medium","gaps":["Transcriptional regulation of EPLIN-beta isoform not identified","In vivo relevance not tested"]},{"year":2011,"claim":"Multiple groups established that junctional tension retains LIMA1 at adherens junctions and that LIMA1 cooperates with vinculin to maintain zonula adherens integrity, defining it as a mechanosensitive junction regulator in both epithelial and endothelial cells.","evidence":"Alpha-catenin–EPLIN fusion rescue; mechanical perturbation and live imaging; GST pulldown and Co-IP in endothelial cells with Matrigel tube formation","pmids":["21844208","22194609","21625216"],"confidence":"High","gaps":["Force range required for LIMA1 retention not quantified","Whether catch-bond or slip-bond mechanism applies unknown"]},{"year":2012,"claim":"Showing that EGF triggers ERK-dependent phosphorylation, ubiquitination, and proteasomal degradation of LIMA1 unified the phosphorylation and turnover pathways into a single growth-factor-regulated degradation cascade.","evidence":"Phospho-site mutagenesis conferring resistance to EGF-induced turnover; ubiquitination assay; cycloheximide chase in prostate cancer cells","pmids":["23188829"],"confidence":"High","gaps":["E3 ligase responsible for phosphorylation-triggered ubiquitination not identified in this study"]},{"year":2015,"claim":"Three contemporaneous studies expanded LIMA1's functional repertoire: API2-MALT1 paracaspase cleaves LIMA1 to generate an oncogenic LIM fragment in MALT lymphoma, LIMA1 interacts with PINCH-1 at focal adhesions to control keratinocyte spreading, and LIMA1 promotes apical extrusion of transformed cells.","evidence":"Paracaspase cleavage assay with active-site mutant controls validated in primary tumors; PINCH-1 interactome by MS with conditional KO; mixed culture extrusion assay with epistasis","pmids":["25569716","25609703","25609711"],"confidence":"High","gaps":["Whether the oncogenic LIM fragment acts through a gain-of-function binding partner or dominant-negative mechanism is unclear","How PINCH-1 recruits LIMA1 structurally is unknown"]},{"year":2018,"claim":"Identification of LIMA1 as a bridge between NPC1L1 and myosin Vb in the intestinal brush border, with Lima1 KO mice showing reduced cholesterol absorption, established a non-cytoskeletal physiological role in cholesterol metabolism validated by human genetic data.","evidence":"Human frameshift variant; Lima1 KO mouse with cholesterol absorption measurements; Co-IP of LIMA1 with NPC1L1 and myosin Vb","pmids":["29880681"],"confidence":"High","gaps":["Whether LIMA1 actively participates in vesicle motility or serves as a passive scaffold is unresolved","Stoichiometry of the NPC1L1–LIMA1–myosin Vb complex unknown"]},{"year":2019,"claim":"FRAP and isoform-specific analysis demonstrated that EPLIN-alpha terminates Arp2/3-driven branching at protrusions while EPLIN-beta stabilizes stress fibers with slower turnover, functionally distinguishing the two isoforms at the subcellular level.","evidence":"Isoform-specific overexpression/depletion; FRAP dynamics; co-localization with Arp2/3 in endothelial cells under shear","pmids":["31644899"],"confidence":"High","gaps":["Whether the N-terminal extension of EPLIN-beta mediates its preferential stress fiber association is not mapped","In vivo isoform-specific functions not tested"]},{"year":2020,"claim":"Discovery that LIMA1 interacts with LUZP1 to restrict ciliogenesis by mobilizing ARP2 to centrosomes and limiting MyosinVa accumulation linked LIMA1 to centrosome biology and primary cilium regulation.","evidence":"BioID proximity proteomics; siRNA depletion increasing cilia formation; centrosome MyosinVa immunofluorescence","pmids":["32496561"],"confidence":"Medium","gaps":["Whether LIMA1 directly binds centrosomal structures or acts indirectly through actin is unclear","In vivo ciliogenesis phenotype not examined"]},{"year":2021,"claim":"Identification of Rab40b–Cullin5 as an E3 complex that locally ubiquitinates and degrades LIMA1 at focal adhesions established a spatially restricted degradation mechanism controlling adhesion dynamics and invadopodia formation.","evidence":"Co-IP of Rab40b with Cullin5 and EPLIN; direct ubiquitylation assay; interaction mutants; migration and invasion rescue","pmids":["33999101"],"confidence":"High","gaps":["Whether Rab40b–Cullin5 targets a specific LIMA1 isoform preferentially is unknown","Ubiquitination sites on LIMA1 not mapped"]},{"year":2022,"claim":"In pluripotent stem cells, Lima1 expression controlled by the naive pluripotency circuit suppresses membrane blebbing and supports mitochondrial energetics, revealing a developmental context for LIMA1 function beyond epithelial junctions.","evidence":"Lima1 KO and forced expression in mouse ESCs; live imaging; mitochondrial respiration assay; chimera assay","pmids":["35105859"],"confidence":"Medium","gaps":["Mechanism by which LIMA1 influences mitochondrial energetics is unexplained","Whether this reflects direct or indirect actin-dependent effect unknown"]},{"year":2023,"claim":"Two studies revealed additional layers of LIMA1 turnover control: Az1/OAZ1 degrades EPLIN-beta in a ubiquitin-independent, proteasome-dependent manner, while USP44 deubiquitinates LIMA1 and its nuclear sequestration by MAD2 promotes LIMA1 K48-ubiquitination.","evidence":"Quantitative proteomics identifying EPLIN-beta as Az1 substrate with Co-IP; USP44–LIMA1 Co-IP with K48-ubiquitination assay and nuclear fractionation","pmids":["37325974","37752233"],"confidence":"Medium","gaps":["Whether Az1 and ubiquitin-dependent pathways compete or act on distinct pools is unknown","Identity of the E3 ligase in the MAD2/USP44 axis not established"]},{"year":2024,"claim":"Multiple 2024 studies identified new LIMA1 regulatory inputs and partners: O-GlcNAcylation at T662 stabilizes LIMA1 to promote hepatic steatosis via β-catenin/FASn, RNF40 ubiquitinates LIMA1 to reduce lipid content, SEPT9 binds the LIM domain to regulate filopodia, and p62 stabilizes LIMA1 protein levels.","evidence":"O-GlcNAc site mapping by MS with T662A knock-in mice; RNF40 Co-IP with domain mapping and ubiquitination assay; SEPT9 KO fibroblasts with EPLIN rescue; GST pulldown of p62 with EPLIN","pmids":["39921472","38909032","38719752","38185251"],"confidence":"High","gaps":["Interplay among the multiple E3 ligases (Rab40b-Cul5, RNF40, STUB1) targeting LIMA1 is not clarified","Structural basis of O-GlcNAc protection from ubiquitination unknown"]},{"year":2025,"claim":"LIMA1 forms a ternary complex with IRBIT and the Cl⁻/HCO₃⁻ exchanger SLC26A3 at the brush border, and LIMA1 knockdown selectively impairs cAMP/ATP-stimulated DRA transport activity, extending LIMA1's scaffolding role to intestinal ion transport regulation.","evidence":"Co-IP of DRA with IRBIT and LIMA1; siRNA knockdown; functional SLC26A3 transport assay in intestinal cells","pmids":["40569378"],"confidence":"Medium","gaps":["Whether LIMA1 binds DRA or IRBIT directly vs. through actin is unresolved","In vivo ion transport phenotype in Lima1 KO intestine not tested"]},{"year":null,"claim":"Key unresolved questions include the structural basis of LIMA1's isoform-specific functions, how multiple E3 ligases and the Az1 pathway are coordinated to achieve spatiotemporal control of LIMA1 levels, and whether LIMA1's roles in cholesterol absorption, ciliogenesis, and junction remodeling converge on a unified actin-scaffolding mechanism.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of LIMA1 bound to actin or alpha-catenin","Isoform-specific knockout mice not generated","Integration of O-GlcNAcylation, ERK phosphorylation, and multiple ubiquitin ligase pathways in a single model system not achieved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,1,2,3,4,18]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[4,7,15,30]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,6,18]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,1,2,5,18]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[3,15,18]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4,13]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[32]}],"pathway":[{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[4,6,7,8]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[5]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[3,9,10,22,27]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[9,20,23,24,25,31]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[15,30]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[15,27]}],"complexes":["E-cadherin–catenin–EPLIN junctional complex","NPC1L1–LIMA1–myosin Vb transport complex","Rab40b–Cullin5 ubiquitin ligase complex (as substrate)"],"partners":["CTNNA1","NPC1L1","MYO5B","SEPT2","SEPT9","LUZP1","PINCH1","RNF40"],"other_free_text":[]},"mechanistic_narrative":"LIMA1 (EPLIN) is a cytoskeletal scaffolding protein that stabilizes actin filaments, links cadherin–catenin adhesion complexes to the cortical actin network, and bridges membrane transporters to motor-driven trafficking machinery. It directly binds and cross-links F-actin through two actin-binding sites, inhibits Arp2/3-mediated branched nucleation, and is recruited to adherens junctions via alpha-catenin in a tension-dependent manner, where it maintains the circumferential actin belt and cooperates with vinculin to preserve zonula adherens integrity [PMID:12566430, PMID:18093941, PMID:21844208]. LIMA1 stability and localization are tightly controlled by ERK-mediated phosphorylation (reducing actin affinity), O-GlcNAcylation at T662 (blocking ubiquitin-dependent degradation), and multiple E3 ubiquitin ligase pathways including Rab40b–Cullin5, RNF40, and STUB1, which target it for proteasomal turnover to regulate focal adhesion dynamics, cell migration, and lipid metabolism [PMID:17875928, PMID:33999101, PMID:39921472, PMID:38909032]. In the intestinal brush border, LIMA1 bridges the cholesterol transporter NPC1L1 to a myosin Vb transport complex, and Lima1-deficient mice are resistant to diet-induced hypercholesterolemia; a human frameshift variant in LIMA1 is linked to reduced cholesterol absorption [PMID:29880681]."},"prefetch_data":{"uniprot":{"accession":"Q9UHB6","full_name":"LIM domain and actin-binding protein 1","aliases":["Epithelial protein lost in neoplasm"],"length_aa":759,"mass_kda":85.2,"function":"Actin-binding protein involved in actin cytoskeleton regulation and dynamics. Increases the number and size of actin stress fibers and inhibits membrane ruffling. Inhibits actin filament depolymerization. Bundles actin filaments, delays filament nucleation and reduces formation of branched filaments (PubMed:12566430, PubMed:33999101). Acts as a negative regulator of primary cilium formation (PubMed:32496561). Plays a role in cholesterol homeostasis. Influences plasma cholesterol levels through regulation of intestinal cholesterol absorption. May act as a scaffold protein by regulating NPC1L1 transportation, an essential protein for cholesterol absorption, to the plasma membrane by recruiting MYO5B to NPC1L1, and thus facilitates cholesterol uptake (By similarity)","subcellular_location":"Cytoplasm; Cell junction, focal adhesion; Cytoplasm, cytoskeleton; Cytoplasm, cytoskeleton, stress fiber; Cell membrane; Cell projection, ruffle; Cell projection, lamellipodium","url":"https://www.uniprot.org/uniprotkb/Q9UHB6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LIMA1","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALD1","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LIMA1","total_profiled":1310},"omim":[{"mim_id":"618079","title":"LOW DENSITY LIPOPROTEIN CHOLESTEROL LEVEL QUANTITATIVE TRAIT LOCUS 8; LDLCQ8","url":"https://www.omim.org/entry/618079"},{"mim_id":"608364","title":"LIM DOMAIN AND ACTIN-BINDING PROTEIN 1; LIMA1","url":"https://www.omim.org/entry/608364"},{"mim_id":"601422","title":"LEUCINE ZIPPER PROTEIN 1; LUZP1","url":"https://www.omim.org/entry/601422"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Actin filaments","reliability":"Approved"},{"location":"Focal adhesion sites","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LIMA1"},"hgnc":{"alias_symbol":["EPLIN"],"prev_symbol":[]},"alphafold":{"accession":"Q9UHB6","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UHB6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UHB6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UHB6-F1-predicted_aligned_error_v6.png","plddt_mean":51.72},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LIMA1","jax_strain_url":"https://www.jax.org/strain/search?query=LIMA1"},"sequence":{"accession":"Q9UHB6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UHB6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UHB6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UHB6"}},"corpus_meta":[{"pmid":"18093941","id":"PMC_18093941","title":"EPLIN mediates linkage of the cadherin catenin complex to F-actin and stabilizes the circumferential actin 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curative intent surgery response in HPV negative head and neck cancer.","date":"2025","source":"EMBO molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40676267","citation_count":0,"is_preprint":false},{"pmid":"41540000","id":"PMC_41540000","title":"Bisphosphate nucleotidase 1 promotes progression and docetaxel resistance in triple-negative breast cancer via STUB1-mediated destabilization of LIMA1.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/41540000","citation_count":0,"is_preprint":false},{"pmid":"41360228","id":"PMC_41360228","title":"Albacarcin V adds EPLIN as a novel and promising target for the treatment of female cancers and pediatric medulloblastoma.","date":"2025","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/41360228","citation_count":0,"is_preprint":false},{"pmid":"39730634","id":"PMC_39730634","title":"EPLIN, a prospective oncogenic molecule with contribution to growth, migration and drug resistance in pancreatic cancer.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/39730634","citation_count":0,"is_preprint":false},{"pmid":"40269880","id":"PMC_40269880","title":"LIMA1 inhibits cisplatin resistance and malignant biological behavior of bladder cancer cells by suppressing the Wnt/β-catenin pathway.","date":"2025","source":"BMC medical genomics","url":"https://pubmed.ncbi.nlm.nih.gov/40269880","citation_count":0,"is_preprint":false},{"pmid":"41253111","id":"PMC_41253111","title":"Checking in with EPLIN: EPLINα as a regulator of integrin trafficking.","date":"2025","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/41253111","citation_count":0,"is_preprint":false},{"pmid":"40569378","id":"PMC_40569378","title":"IRBIT and LIMA1 associate with and are necessary for epithelial cell SLC26A3 (DRA) stimulation by cAMP/ATP.","date":"2025","source":"American journal of physiology. Cell physiology","url":"https://pubmed.ncbi.nlm.nih.gov/40569378","citation_count":0,"is_preprint":false},{"pmid":"41596426","id":"PMC_41596426","title":"Inhibition of Breast Cancer Bone Metastasis by LRP5-Overexpressing Osteocytes via the LIMA1/MYO5B Signaling Axis.","date":"2026","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41596426","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.10.686758","title":"The anti-retroviral therapy emtricitabine affects skeletal muscle DNA methylation and transcriptome patterns in a male HIV mouse model","date":"2025-11-11","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.10.686758","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.06.25.661584","title":"Phosphoproteomics unveils the signaling dynamics in neuronal cells stimulated with insulin and insulin-like growth factors","date":"2025-06-28","source":"bioRxiv","url":"https://doi.org/10.1101/2025.06.25.661584","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.06.27.600789","title":"EPLINα controls integrin recycling from Rab21 endosomes to drive breast cancer cell migration","date":"2024-06-28","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.27.600789","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.06.04.597350","title":"E cadherin appears to be an essential on/off switch for initiating bile canaliculi formation","date":"2024-06-05","source":"bioRxiv","url":"https://doi.org/10.1101/2024.06.04.597350","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":28817,"output_tokens":7937,"usd":0.102753},"stage2":{"model":"claude-opus-4-6","input_tokens":11739,"output_tokens":4686,"usd":0.263767},"total_usd":0.36652,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"EPLIN directly binds actin filaments at two distinct binding sites, inhibits actin filament depolymerization, cross-links filaments into bundles, and inhibits branching nucleation by the Arp2/3 complex via side-binding activity; it does not affect spontaneous polymerization kinetics or barbed-end elongation.\",\n      \"method\": \"In vitro biochemical assays with purified recombinant EPLIN (depolymerization assay, bundling/cross-linking assay, Arp2/3-mediated nucleation assay, actin polymerization kinetics)\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple in vitro reconstitution assays with purified protein, foundational mechanistic paper with high citation count\",\n      \"pmids\": [\"12566430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"EPLIN is a cytoskeletal protein with a single central LIM domain that localizes to filamentous actin and suppresses cell proliferation when overexpressed; two isoforms (alpha, 600 aa; beta, 759 aa) are generated from a single gene.\",\n      \"method\": \"Subcellular localization by immunofluorescence; overexpression in epithelial cells with proliferation assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — original discovery paper with direct localization and functional assay, single lab\",\n      \"pmids\": [\"10618726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The N-terminal region of EPLIN is required for both its localization to the actin cytoskeleton and suppression of anchorage-independent growth; loss of cytoskeletal localization (as in Ras-transformed cells) abolishes the tumor-suppressive function.\",\n      \"method\": \"Retroviral transduction of truncated EPLIN constructs in NIH3T3 cells; soft-agar colony formation assay; immunofluorescence localization\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-deletion mutagenesis with functional readout, single lab\",\n      \"pmids\": [\"11950948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ERK phosphorylates EPLIN at Ser360, Ser602, and Ser692; phosphorylation of the C-terminal region reduces EPLIN's affinity for actin filaments. ERK-mediated phosphorylation drives redistribution of EPLIN from stress fibers to membrane ruffles and is required for PDGF-induced stress fiber disassembly, membrane ruffling, and cell migration.\",\n      \"method\": \"In vitro kinase assay with purified ERK and EPLIN; phospho-specific antibodies in intact cells; non-phosphorylatable mutant overexpression; wound healing and migration assays; PDGF stimulation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay plus mutagenesis plus functional phenotype, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"17875928\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"EPLIN (LIMA1) couples with alpha-catenin and links the E-cadherin–catenin complex to F-actin at adherens junctions. EPLIN depletion disorganizes the circumferential actin adhesion belt, converting it to zipper-like junctions with radially arranged actin, without affecting non-junctional actin fibers.\",\n      \"method\": \"Co-immunoprecipitation of EPLIN with alpha-catenin; siRNA depletion in epithelial cells; immunofluorescence of actin and junctional markers\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus clean KD with specific morphological phenotype, high citation count, replicated in endothelial cells\",\n      \"pmids\": [\"18093941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"EPLIN localizes to the cleavage furrow during cytokinesis via association with contractile ring components myosin II and the septin Sept2; EPLIN depletion causes multinucleation due to inefficient accumulation of active myosin II (MRLC-S19), Sept2, RhoA, and Cdc42 at the furrow.\",\n      \"method\": \"Immunofluorescence localization during cytokinesis; Co-immunoprecipitation with myosin II and Sept2; siRNA depletion with multinucleation quantification\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — direct localization with functional consequence plus Co-IP, single lab\",\n      \"pmids\": [\"19221476\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Junctional tension is required to retain EPLIN at adherens junctions; lateral actin fiber forces inhibit EPLIN–AJ association. An alpha-catenin–EPLIN fusion promotes zonula adherens (ZA) formation but not punctate AJ formation, placing EPLIN as a mechanosensitive regulator downstream of tension at the ZA. Vinculin cooperates with EPLIN to maintain ZA integrity.\",\n      \"method\": \"Live imaging of EPLIN at junctions with mechanical perturbation; rescue experiments with alpha-catenin–EPLIN fusion construct; vinculin depletion combined with EPLIN depletion\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic and pharmacological perturbations with defined mechanosensitive phenotype, replicated concept from prior work\",\n      \"pmids\": [\"21844208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"EPLIN interacts directly with alpha-catenin and tethers the VE-cadherin–catenin complex to the actin cytoskeleton in endothelial cells; EPLIN depletion delocalizes vinculin from junctions and reduces pseudocapillary network formation in a Matrigel angiogenesis assay.\",\n      \"method\": \"Co-immunoprecipitation and GST pulldown of EPLIN with alpha-catenin; siRNA depletion; immunofluorescence; Matrigel tube formation assay; blebbistatin treatment\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — GST pulldown plus reciprocal Co-IP plus functional assay; extends epithelial finding to endothelial system\",\n      \"pmids\": [\"22194609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"EPLIN depletion during epithelial-mesenchymal transition in prostate cancer cells causes disassembly of adherens junctions, actin remodeling, and activation of beta-catenin signaling, establishing EPLIN as a negative regulator of EMT.\",\n      \"method\": \"siRNA depletion; immunofluorescence of junctional markers; beta-catenin reporter assay; quantitative proteomics in EMT model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple assays in experimental EMT model, single lab\",\n      \"pmids\": [\"21625216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"EGF promotes ERK1/2-dependent phosphorylation, ubiquitination, and proteasomal degradation of EPLIN; Ser362 and Ser604 are the critical ERK1/2 phosphorylation sites whose mutation confers resistance to EGF-induced EPLIN turnover.\",\n      \"method\": \"EGF stimulation of prostate cancer cells; ERK1/2 inhibitor treatment; phospho-site mutagenesis; ubiquitination assay; cycloheximide chase\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — site-directed mutagenesis plus ubiquitination assay plus pharmacological rescue, multiple orthogonal methods\",\n      \"pmids\": [\"23188829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"DNp73 drives loss of EPLIN expression, which de-represses IGF1R signaling and activates AKT/STAT3 to promote migration and invasion; EPLIN acts as a direct inhibitor of IGF1R-AKT/STAT3 activation downstream of the p73/DNp73 axis.\",\n      \"method\": \"Knockdown/overexpression of DNp73 and EPLIN; xenograft invasion/metastasis assay; signaling pathway analysis by Western blot; co-expression rescue experiments\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro and in vivo epistasis with pathway readout, single lab\",\n      \"pmids\": [\"24135282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"API2-MALT1 fusion protein cleaves LIMA1 via MALT1 paracaspase activity; API2 mediates LIMA1 binding, and proteolysis generates an oncogenic LIM-domain-only fragment that promotes lymphomagenesis. Primary MALT lymphomas harboring API2-MALT1 uniquely show LIMA1 cleavage fragments.\",\n      \"method\": \"Co-immunoprecipitation; paracaspase cleavage assay with API2-MALT1 mutants; in vitro and in vivo oncogenicity assays; primary tumor immunoblot for cleavage products\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct cleavage assay with active-site mutant controls, validated in primary patient tumors\",\n      \"pmids\": [\"25569716\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"EPLIN functions upstream of Caveolin-1 in RasV12-transformed cells surrounded by normal cells, promoting apical extrusion; EPLIN regulates non-cell-autonomous myosin-II and PKA activation in transformed cells and affects filamin A accumulation in neighboring normal cells.\",\n      \"method\": \"siRNA depletion; mixed culture of normal and RasV12-transformed cells; live imaging of apical extrusion; epistasis experiments (EPLIN KD upstream of Cav-1 KD)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis in defined cellular context with quantified extrusion phenotype\",\n      \"pmids\": [\"25609711\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PINCH-1 interacts with EPLIN at integrin adhesion sites in keratinocytes; EPLIN localization to focal adhesions is PINCH-1-dependent; EPLIN depletion severely attenuates keratinocyte spreading and migration on collagen and fibronectin independently of PINCH-1 levels.\",\n      \"method\": \"PINCH-1 interactome by mass spectrometry; co-immunoprecipitation; PINCH-1 conditional knockout in epidermis; EPLIN siRNA depletion; adhesion and migration assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — MS interactome plus in vivo KO plus in vitro functional assays, multiple orthogonal approaches\",\n      \"pmids\": [\"25609703\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"p53 transcriptionally induces LIMA1 expression by binding two p53 response elements in the LIMA1 gene; LIMA1 mediates p53-dependent suppression of cancer cell invasion.\",\n      \"method\": \"ChIP-seq for p53 binding; microarray identification of LIMA1 as p53 target; nutlin-3a activation of endogenous p53; LIMA1 knockdown in p53 invasion-suppression assay\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP-seq with functional epistasis (KD partially reverses p53 effect), single lab\",\n      \"pmids\": [\"28093207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LIMA1 is expressed in the small intestinal brush border membrane and bridges NPC1L1 (the cholesterol transporter) to a myosin Vb-containing transport complex, facilitating intestinal cholesterol uptake. Lima1-deficient mice show reduced cholesterol absorption and resistance to diet-induced hypercholesterolemia.\",\n      \"method\": \"Rare frameshift variant identification in family; Lima1 KO mouse model; brush border fractionation; co-immunoprecipitation of LIMA1 with NPC1L1 and myosin Vb; cholesterol absorption measurements\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — KO mouse plus Co-IP complex identification plus human genetic validation, high citation count\",\n      \"pmids\": [\"29880681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Paxillin binds EPLIN specifically in RasV12-transformed cells surrounded by normal cells; paxillin, plectin, and EPLIN mutually influence their accumulation and cooperate to promote acetylated tubulin enrichment via paxillin-mediated suppression of HDAC6, facilitating apical extrusion.\",\n      \"method\": \"Co-immunoprecipitation of paxillin with EPLIN in mixed culture; siRNA depletion; immunofluorescence of acetylated tubulin and HDAC6 activity assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP in defined cellular context plus epistasis, single lab\",\n      \"pmids\": [\"29391412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"EPLIN-alpha transcription is regulated by the actin-MAL/MRTF-SRF signaling pathway; monomeric actin represses MAL-SRF-dependent EPLIN-alpha expression, while conditions that release MAL from G-actin induce EPLIN-alpha but not EPLIN-beta, revealing isoform-specific transcriptional control.\",\n      \"method\": \"Transcriptome analysis with actin-binding drugs; dominant-negative MAL overexpression; constitutively active actin mutants; MAL/SRF ChIP at EPLIN-alpha promoter; promoter-reporter assays\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus pharmacological and genetic perturbation of pathway, multiple complementary approaches\",\n      \"pmids\": [\"20236507\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"EPLIN-alpha localizes to membrane protrusions and interacts with the Arp2/3 complex to terminate branched actin growth, while EPLIN-beta localizes to stress fibers and stabilizes them; FRAP shows lower EPLIN-beta turnover rate, consistent with a filament-stabilizing role distinct from EPLIN-alpha's protrusion-regulating function.\",\n      \"method\": \"Isoform-specific overexpression and depletion; FRAP of EPLIN-alpha vs. -beta; co-localization with Arp2/3; shear stress experiments in aortic vs. vena cava endothelial cells\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — FRAP plus isoform-specific functional assays plus multiple cellular contexts, multiple orthogonal methods\",\n      \"pmids\": [\"31644899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"EPLIN interacts with LUZP1 and together they restrict primary cilia formation; depleting either EPLIN or LUZP1 increases MyosinVa at the centrosome and promotes ciliogenesis. EPLIN and LUZP1 stabilize actin dynamics at least partly by mobilizing ARP2 to centrosomes.\",\n      \"method\": \"Proximity ligation/BioID interactome; siRNA depletion of EPLIN or LUZP1; cilia quantification; centrosome MyosinVa immunofluorescence; actin dynamics assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — BioID interaction plus KD phenotype with centrosome/cilia readout, single lab\",\n      \"pmids\": [\"32496561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rab40b interacts with Cullin5 via its SOCS domain and EPLIN is a binding partner and substrate for Rab40b-Cullin5-dependent localized ubiquitylation and degradation; loss of this ubiquitylation increases EPLIN levels, stabilizes focal adhesions, and reduces cell migration and invadopodia formation.\",\n      \"method\": \"Co-immunoprecipitation of Rab40b with Cullin5 and EPLIN; ubiquitylation assay; Rab40b-Cullin5 interaction mutants; EPLIN degradation rescue experiments; migration and invasion assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct ubiquitylation assay plus interaction mutant plus functional rescue, multiple orthogonal methods\",\n      \"pmids\": [\"33999101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Lima1 expression is controlled by the naive pluripotency circuit in mouse embryonic stem cells and is required to suppress membrane blebbing and maintain proper mitochondrial energetics; forced Lima1 expression enables primed pluripotent cells to incorporate into pre-implantation embryos.\",\n      \"method\": \"Lima1 KO and overexpression in mouse ESCs; live imaging of membrane blebbing; mitochondrial respiration assay; chimera assay in pre-implantation embryos\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO with two distinct functional phenotypes plus rescue, single lab\",\n      \"pmids\": [\"35105859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LIMA1 inhibits the Wnt/beta-catenin pathway in hepatocellular carcinoma by binding BMI1 and inducing its destabilization; loss of LIMA1 stabilizes BMI1 and activates beta-catenin signaling to promote HCC proliferation and metastasis.\",\n      \"method\": \"Co-immunoprecipitation of LIMA1 with BMI1; overexpression/knockdown of LIMA1; beta-catenin reporter assay; xenograft mouse model\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — Co-IP plus functional assay, single lab\",\n      \"pmids\": [\"36497115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"EPLIN-beta (but not EPLIN-alpha) is a novel substrate of ornithine decarboxylase antizyme 1 (Az1/OAZ1); Az1 degrades EPLIN-beta in a ubiquitination-independent, proteasome-mediated manner; Az1 absence elevates EPLIN-beta and causes enhanced cellular migration.\",\n      \"method\": \"Quantitative proteomics to identify Az1 substrates; co-immunoprecipitation of EPLIN-beta with Az1; ubiquitination assay (showing independence); proteasome inhibitor rescue; migration assay after Az1 KO\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — proteomics identification plus Co-IP plus mechanistic ubiquitination assay, single lab\",\n      \"pmids\": [\"37325974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MAD2 sequesters USP44 in the nucleus, preventing USP44 from binding and deubiquitinating LIMA1, leading to enhanced K48-linked ubiquitination and degradation of LIMA1 and consequent activation of IGF1R/PI3K/AKT signaling in cholangiocarcinoma.\",\n      \"method\": \"Co-immunoprecipitation of USP44 with LIMA1; ubiquitination assay (K48-linked); nuclear fractionation showing MAD2 sequestration of USP44; pathway activation by Western blot; PDTX model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus K48-ubiquitination assay plus functional pathway readout, single lab\",\n      \"pmids\": [\"37752233\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"RNF40, an E3 ubiquitin ligase, mediates ubiquitination and proteasomal degradation of LIMA1; the 1–166 aa fragment of LIMA1 is indispensable for the LIMA1–RNF40 interaction. RNF40-mediated LIMA1 degradation reduces cellular lipid content, which is reversed by LIMA1 overexpression.\",\n      \"method\": \"Co-immunoprecipitation of RNF40 with LIMA1; domain-mapping with truncation mutants; ubiquitination assay; proteasome inhibitor rescue; lipid content measurement\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP with domain mapping plus ubiquitination assay plus functional lipid readout, single lab\",\n      \"pmids\": [\"38909032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cytoplasmic p62 (SQSTM1) interacts with EPLIN via GST pulldown and enhances EPLIN protein stability; elevated EPLIN in ESCC promotes migration and invasion, and reducing EPLIN expression inhibits these phenotypes.\",\n      \"method\": \"GST pulldown of p62 with EPLIN; p62 knockdown/overexpression with localization control; EPLIN rescue after p62 KD; migration and invasion assays\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — GST pulldown plus functional rescue, single lab\",\n      \"pmids\": [\"38185251\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LIMA1 O-GlcNAcylation at T662 (catalyzed by OGT, promoted by steatosis-induced HCF1/OGT upregulation) inhibits its ubiquitin-dependent degradation and enhances hepatocyte lipid deposition via activation of beta-catenin/FASn signaling; LIMA1-T662A mutant mice showed reduced steatosis, inflammation, and fibrosis.\",\n      \"method\": \"O-GlcNAc site mapping by mass spectrometry; site-directed mutagenesis (T662A); AAV-mediated liver-specific expression in LIMA1 HKO mice; beta-catenin/FASn pathway analysis by Western blot; OGT inhibitor studies\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — PTM site identification by MS plus mutagenesis plus in vivo mouse model, multiple orthogonal methods\",\n      \"pmids\": [\"39921472\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LIMA1 interacts with PINK1 and inhibits PINK1-Parkin-mediated mitophagy in hepatic stellate cells; LIMA1 delivered via lipotoxic hepatocyte-derived small extracellular vesicles promotes HSC activation by blocking mitophagy.\",\n      \"method\": \"Molecular docking and database prediction; LIMA1 KD in LX2 cells; mt-keima lentivirus to detect mitophagy; sEV isolation and delivery assay; in vivo HFD mouse model\",\n      \"journal\": \"Cellular & molecular biology letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3–4 — interaction predicted by docking, functional KD data without direct biochemical LIMA1-PINK1 binding validation\",\n      \"pmids\": [\"38822260\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SEPT9 directly interacts with the LIM domain of EPLIN; this interaction regulates actin stress fiber and filopodia organization, focal adhesion size, and cell adhesion and migration in human fibroblasts. Increased EPLIN levels can partially rescue the low motility of SEPT9 KO cells.\",\n      \"method\": \"SEPT9 KO fibroblast cell line; co-expression and interaction assays; immunofluorescence of actin structures and focal adhesions; migration assays with rescue by EPLIN overexpression\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — KO with genetic rescue plus LIM domain interaction characterization, single lab\",\n      \"pmids\": [\"38719752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"IRBIT and LIMA1 form a complex with the brush border Cl-/HCO3- exchanger SLC26A3 (DRA); cAMP/ATP stimulation increases the association of LIMA1 with both IRBIT and DRA; LIMA1 knockdown selectively reduces cAMP plus ATP stimulation of DRA activity without affecting basal activity.\",\n      \"method\": \"Co-immunoprecipitation of DRA with IRBIT and LIMA1; LIMA1 siRNA knockdown; functional SLC26A3 transport assay with pharmacological stimulation; brush border fractionation\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional transport assay with KD, single lab\",\n      \"pmids\": [\"40569378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"BPNT1 recruits E3 ubiquitin ligase STUB1 to induce proteasomal degradation of LIMA1, promoting EMT and TNBC progression; re-expression of LIMA1 in BPNT1-overexpressing cells partially reverses EMT and malignant phenotypes.\",\n      \"method\": \"Co-immunoprecipitation of BPNT1 with STUB1 and LIMA1; ubiquitination/degradation assay; LIMA1 re-expression rescue; xenograft mouse model; in vitro invasion/migration assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus ubiquitination assay plus in vivo rescue, single lab\",\n      \"pmids\": [\"41540000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"EPLINα localizes to Rab21-positive recycling endosomes (in addition to actin ruffles) via its actin-binding activity; EPLINα interacts with Rab21 and supports beta1-integrin recycling and cell migration. Coronin 1C is an EPLIN-proximal protein at Rab21 endosomes in an EPLINα-dependent manner. High EPLINα-to-EPLINβ ratio correlates with mesenchymal phenotype in breast cancer.\",\n      \"method\": \"Isoform-specific localization by live imaging; BioID proximity proteomics; Co-localization of EPLINα with Rab21 and F-actin on endosomes; actin-binding mutant; integrin recycling assay\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — BioID plus direct co-localization plus functional integrin recycling assay, single lab preprint\",\n      \"pmids\": [\"bio_10.1101_2024.06.27.600789\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"LIMA1/EPLIN is a dual-function actin-binding protein that (1) cross-links and stabilizes actin filaments while inhibiting Arp2/3-mediated branched nucleation, (2) links the cadherin–catenin complex to F-actin at adherens junctions in a mechanosensitive, tension-dependent manner, (3) undergoes ERK-mediated phosphorylation and RNF40/STUB1/Rab40b-Cullin5-mediated ubiquitin–proteasomal degradation that regulate its actin affinity and stability, (4) bridges NPC1L1 to a myosin Vb transport complex to facilitate intestinal cholesterol absorption, (5) is cleaved by the API2-MALT1 paracaspase to generate an oncogenic LIM-domain fragment, and (6) controls cytokinesis, ciliogenesis, integrin recycling, and mechanosensitive junction remodeling through isoform-specific interactions with alpha-catenin, PINCH-1, Rab21, LUZP1, and septins.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"LIMA1 (EPLIN) is a cytoskeletal scaffolding protein that stabilizes actin filaments, links cadherin–catenin adhesion complexes to the cortical actin network, and bridges membrane transporters to motor-driven trafficking machinery. It directly binds and cross-links F-actin through two actin-binding sites, inhibits Arp2/3-mediated branched nucleation, and is recruited to adherens junctions via alpha-catenin in a tension-dependent manner, where it maintains the circumferential actin belt and cooperates with vinculin to preserve zonula adherens integrity [PMID:12566430, PMID:18093941, PMID:21844208]. LIMA1 stability and localization are tightly controlled by ERK-mediated phosphorylation (reducing actin affinity), O-GlcNAcylation at T662 (blocking ubiquitin-dependent degradation), and multiple E3 ubiquitin ligase pathways including Rab40b–Cullin5, RNF40, and STUB1, which target it for proteasomal turnover to regulate focal adhesion dynamics, cell migration, and lipid metabolism [PMID:17875928, PMID:33999101, PMID:39921472, PMID:38909032]. In the intestinal brush border, LIMA1 bridges the cholesterol transporter NPC1L1 to a myosin Vb transport complex, and Lima1-deficient mice are resistant to diet-induced hypercholesterolemia; a human frameshift variant in LIMA1 is linked to reduced cholesterol absorption [PMID:29880681].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Establishing LIMA1 as a novel LIM-domain cytoskeletal protein with two isoforms answered whether the gene encoded a structural or signaling factor, placing it at actin filaments with growth-suppressive properties.\",\n      \"evidence\": \"Immunofluorescence localization to F-actin and overexpression proliferation assay in epithelial cells\",\n      \"pmids\": [\"10618726\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of proliferation suppression unknown\", \"No biochemical actin-binding data yet\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Mapping the N-terminal region as essential for both actin localization and anchorage-independent growth suppression established that cytoskeletal targeting is required for LIMA1's tumor-suppressive function.\",\n      \"evidence\": \"Truncated EPLIN constructs in NIH3T3 cells with soft-agar colony formation and immunofluorescence\",\n      \"pmids\": [\"11950948\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific actin-binding domains not yet biochemically defined\", \"No in vivo tumor model\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Reconstitution with purified protein demonstrated that LIMA1 directly binds, bundles, and stabilizes actin filaments while inhibiting Arp2/3-mediated branching, defining its core biochemical activities.\",\n      \"evidence\": \"In vitro depolymerization, bundling, and Arp2/3 nucleation assays with purified recombinant EPLIN\",\n      \"pmids\": [\"12566430\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of the two actin-binding sites in cells unknown\", \"No structural model of actin–EPLIN interface\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Discovery that ERK phosphorylates LIMA1 at C-terminal serines to reduce actin affinity, redistribute LIMA1 to ruffles, and enable PDGF-induced migration revealed the first post-translational switch controlling LIMA1 function.\",\n      \"evidence\": \"In vitro ERK kinase assay, phospho-site mutagenesis, wound healing assay with PDGF stimulation\",\n      \"pmids\": [\"17875928\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No crystal structure of phosphorylated vs. unphosphorylated actin-binding domain\", \"Whether other kinases target the same sites not tested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identification of LIMA1 as the physical link between alpha-catenin and F-actin at adherens junctions resolved a long-standing question of how the cadherin–catenin complex engages the actin cytoskeleton.\",\n      \"evidence\": \"Reciprocal Co-IP of EPLIN with alpha-catenin; siRNA depletion converting circumferential actin belt to radial zipper junctions in epithelial cells\",\n      \"pmids\": [\"18093941\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the interaction is direct or via additional adaptor proteins at endogenous stoichiometry\", \"Mechanosensitivity not yet tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Localization of LIMA1 to the cleavage furrow via myosin II and septin interactions, and multinucleation upon depletion, extended LIMA1 function beyond junctions to cytokinesis.\",\n      \"evidence\": \"Co-IP with myosin II and Sept2; siRNA depletion with multinucleation quantification\",\n      \"pmids\": [\"19221476\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LIMA1 is required for contractile ring assembly or maintenance not distinguished\", \"No live imaging of furrow dynamics after depletion\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrating that MAL/MRTF–SRF signaling transcriptionally induces only EPLIN-alpha revealed isoform-specific transcriptional regulation linked to the cellular actin monomer/polymer balance.\",\n      \"evidence\": \"MAL/SRF ChIP at EPLIN-alpha promoter; dominant-negative MAL and actin-binding drugs\",\n      \"pmids\": [\"20236507\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcriptional regulation of EPLIN-beta isoform not identified\", \"In vivo relevance not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Multiple groups established that junctional tension retains LIMA1 at adherens junctions and that LIMA1 cooperates with vinculin to maintain zonula adherens integrity, defining it as a mechanosensitive junction regulator in both epithelial and endothelial cells.\",\n      \"evidence\": \"Alpha-catenin–EPLIN fusion rescue; mechanical perturbation and live imaging; GST pulldown and Co-IP in endothelial cells with Matrigel tube formation\",\n      \"pmids\": [\"21844208\", \"22194609\", \"21625216\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Force range required for LIMA1 retention not quantified\", \"Whether catch-bond or slip-bond mechanism applies unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showing that EGF triggers ERK-dependent phosphorylation, ubiquitination, and proteasomal degradation of LIMA1 unified the phosphorylation and turnover pathways into a single growth-factor-regulated degradation cascade.\",\n      \"evidence\": \"Phospho-site mutagenesis conferring resistance to EGF-induced turnover; ubiquitination assay; cycloheximide chase in prostate cancer cells\",\n      \"pmids\": [\"23188829\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"E3 ligase responsible for phosphorylation-triggered ubiquitination not identified in this study\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Three contemporaneous studies expanded LIMA1's functional repertoire: API2-MALT1 paracaspase cleaves LIMA1 to generate an oncogenic LIM fragment in MALT lymphoma, LIMA1 interacts with PINCH-1 at focal adhesions to control keratinocyte spreading, and LIMA1 promotes apical extrusion of transformed cells.\",\n      \"evidence\": \"Paracaspase cleavage assay with active-site mutant controls validated in primary tumors; PINCH-1 interactome by MS with conditional KO; mixed culture extrusion assay with epistasis\",\n      \"pmids\": [\"25569716\", \"25609703\", \"25609711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the oncogenic LIM fragment acts through a gain-of-function binding partner or dominant-negative mechanism is unclear\", \"How PINCH-1 recruits LIMA1 structurally is unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identification of LIMA1 as a bridge between NPC1L1 and myosin Vb in the intestinal brush border, with Lima1 KO mice showing reduced cholesterol absorption, established a non-cytoskeletal physiological role in cholesterol metabolism validated by human genetic data.\",\n      \"evidence\": \"Human frameshift variant; Lima1 KO mouse with cholesterol absorption measurements; Co-IP of LIMA1 with NPC1L1 and myosin Vb\",\n      \"pmids\": [\"29880681\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether LIMA1 actively participates in vesicle motility or serves as a passive scaffold is unresolved\", \"Stoichiometry of the NPC1L1–LIMA1–myosin Vb complex unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"FRAP and isoform-specific analysis demonstrated that EPLIN-alpha terminates Arp2/3-driven branching at protrusions while EPLIN-beta stabilizes stress fibers with slower turnover, functionally distinguishing the two isoforms at the subcellular level.\",\n      \"evidence\": \"Isoform-specific overexpression/depletion; FRAP dynamics; co-localization with Arp2/3 in endothelial cells under shear\",\n      \"pmids\": [\"31644899\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the N-terminal extension of EPLIN-beta mediates its preferential stress fiber association is not mapped\", \"In vivo isoform-specific functions not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Discovery that LIMA1 interacts with LUZP1 to restrict ciliogenesis by mobilizing ARP2 to centrosomes and limiting MyosinVa accumulation linked LIMA1 to centrosome biology and primary cilium regulation.\",\n      \"evidence\": \"BioID proximity proteomics; siRNA depletion increasing cilia formation; centrosome MyosinVa immunofluorescence\",\n      \"pmids\": [\"32496561\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LIMA1 directly binds centrosomal structures or acts indirectly through actin is unclear\", \"In vivo ciliogenesis phenotype not examined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identification of Rab40b–Cullin5 as an E3 complex that locally ubiquitinates and degrades LIMA1 at focal adhesions established a spatially restricted degradation mechanism controlling adhesion dynamics and invadopodia formation.\",\n      \"evidence\": \"Co-IP of Rab40b with Cullin5 and EPLIN; direct ubiquitylation assay; interaction mutants; migration and invasion rescue\",\n      \"pmids\": [\"33999101\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Rab40b–Cullin5 targets a specific LIMA1 isoform preferentially is unknown\", \"Ubiquitination sites on LIMA1 not mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"In pluripotent stem cells, Lima1 expression controlled by the naive pluripotency circuit suppresses membrane blebbing and supports mitochondrial energetics, revealing a developmental context for LIMA1 function beyond epithelial junctions.\",\n      \"evidence\": \"Lima1 KO and forced expression in mouse ESCs; live imaging; mitochondrial respiration assay; chimera assay\",\n      \"pmids\": [\"35105859\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which LIMA1 influences mitochondrial energetics is unexplained\", \"Whether this reflects direct or indirect actin-dependent effect unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Two studies revealed additional layers of LIMA1 turnover control: Az1/OAZ1 degrades EPLIN-beta in a ubiquitin-independent, proteasome-dependent manner, while USP44 deubiquitinates LIMA1 and its nuclear sequestration by MAD2 promotes LIMA1 K48-ubiquitination.\",\n      \"evidence\": \"Quantitative proteomics identifying EPLIN-beta as Az1 substrate with Co-IP; USP44–LIMA1 Co-IP with K48-ubiquitination assay and nuclear fractionation\",\n      \"pmids\": [\"37325974\", \"37752233\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether Az1 and ubiquitin-dependent pathways compete or act on distinct pools is unknown\", \"Identity of the E3 ligase in the MAD2/USP44 axis not established\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Multiple 2024 studies identified new LIMA1 regulatory inputs and partners: O-GlcNAcylation at T662 stabilizes LIMA1 to promote hepatic steatosis via β-catenin/FASn, RNF40 ubiquitinates LIMA1 to reduce lipid content, SEPT9 binds the LIM domain to regulate filopodia, and p62 stabilizes LIMA1 protein levels.\",\n      \"evidence\": \"O-GlcNAc site mapping by MS with T662A knock-in mice; RNF40 Co-IP with domain mapping and ubiquitination assay; SEPT9 KO fibroblasts with EPLIN rescue; GST pulldown of p62 with EPLIN\",\n      \"pmids\": [\"39921472\", \"38909032\", \"38719752\", \"38185251\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay among the multiple E3 ligases (Rab40b-Cul5, RNF40, STUB1) targeting LIMA1 is not clarified\", \"Structural basis of O-GlcNAc protection from ubiquitination unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"LIMA1 forms a ternary complex with IRBIT and the Cl⁻/HCO₃⁻ exchanger SLC26A3 at the brush border, and LIMA1 knockdown selectively impairs cAMP/ATP-stimulated DRA transport activity, extending LIMA1's scaffolding role to intestinal ion transport regulation.\",\n      \"evidence\": \"Co-IP of DRA with IRBIT and LIMA1; siRNA knockdown; functional SLC26A3 transport assay in intestinal cells\",\n      \"pmids\": [\"40569378\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LIMA1 binds DRA or IRBIT directly vs. through actin is unresolved\", \"In vivo ion transport phenotype in Lima1 KO intestine not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of LIMA1's isoform-specific functions, how multiple E3 ligases and the Az1 pathway are coordinated to achieve spatiotemporal control of LIMA1 levels, and whether LIMA1's roles in cholesterol absorption, ciliogenesis, and junction remodeling converge on a unified actin-scaffolding mechanism.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of LIMA1 bound to actin or alpha-catenin\", \"Isoform-specific knockout mice not generated\", \"Integration of O-GlcNAcylation, ERK phosphorylation, and multiple ubiquitin ligase pathways in a single model system not achieved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 1, 2, 3, 4, 18]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [4, 7, 15, 30]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 6, 18]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 1, 2, 5, 18]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 15, 18]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4, 13]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [32]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [4, 6, 7, 8]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 9, 10, 22, 27]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [9, 20, 23, 24, 25, 31]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [15, 30]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [15, 27]}\n    ],\n    \"complexes\": [\n      \"E-cadherin–catenin–EPLIN junctional complex\",\n      \"NPC1L1–LIMA1–myosin Vb transport complex\",\n      \"Rab40b–Cullin5 ubiquitin ligase complex (as substrate)\"\n    ],\n    \"partners\": [\n      \"CTNNA1\",\n      \"NPC1L1\",\n      \"MYO5B\",\n      \"SEPT2\",\n      \"SEPT9\",\n      \"LUZP1\",\n      \"PINCH1\",\n      \"RNF40\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}