{"gene":"ACTN1","run_date":"2026-06-09T22:02:40","timeline":{"discoveries":[{"year":2013,"finding":"ACTN1 mutations within the actin-binding domain (ABD) disrupt normal actin-based cytoskeletal structure in CHO cells and in mouse fetal liver-derived megakaryocytes, causing disorganized cytoskeleton and production of abnormally large proplatelet tips reduced in number, establishing ACTN1's role in megakaryocyte cytoskeletal organization and platelet biogenesis.","method":"In vitro transfection in CHO cells; retroviral transduction of mouse fetal liver-derived megakaryocytes; immunofluorescence; morphological analysis of proplatelet formation","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function in two independent cellular systems (CHO and primary megakaryocytes) with defined phenotypic readouts, replicated across multiple mutation-bearing families","pmids":["23434115"],"is_preprint":false},{"year":2013,"finding":"A missense mutation (p.Arg46Gln) in the actin-binding domain of ACTN1 causes disorganization of the cellular cytoplasm in transfected COS-7 cells, as observed by immunofluorescence, and disorganized megakaryocyte ultrastructure by electron microscopy.","method":"Immunofluorescence in transfected COS-7 cells; electron microscopy of cultured mutation-harboring megakaryocytes","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal methods (IF and EM) in a single lab studying a disease-associated mutation in the functionally critical ABD","pmids":["24069336"],"is_preprint":false},{"year":2015,"finding":"An ACTN1 mutation in the spectrin-like repeat 2 (SLR2) rod domain (p.Leu395Gln), outside the ABD and CaM domains, also causes disorganization of the actin cytoskeleton in CHO cells, demonstrating that rod domain mutations can disrupt ACTN1 cytoskeletal function.","method":"Immunofluorescence in transfected CHO cells","journal":"Annals of hematology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single method (IF) but consistent with mechanistic findings from multiple prior studies of ABD/CaM mutations","pmids":["26453073"],"is_preprint":false},{"year":2019,"finding":"Rod domain ACTN1 variants predicted to hinder dimer formation cause actin network disorganization and increased thickness of actin fibers when expressed in vitro, extending the spectrum of ACTN1 structural domains whose mutation disrupts cytoskeletal function.","method":"In vitro expression of ACTN1 variants; actin network morphology analysis","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single method but assessed multiple novel variants, consistent across the cohort","pmids":["31237726"],"is_preprint":false},{"year":2019,"finding":"Cullin-3 E3-ubiquitin ligase mediates degradation of ACTN1 during myogenesis; loss of Cullin-3 causes accumulation of ACTN1 in muscle. Overexpression of ACTN1 in C2C12 myoblasts triggers defects in fusion, myogenesis, and acetylcholine receptor clustering, establishing that Cullin-3-dependent regulation of ACTN1 protein levels is essential for normal muscle and neuromuscular junction development.","method":"Cullin-3 knockout mice; C2C12 myoblast overexpression; immunofluorescence; acetylcholine receptor clustering assay; proteomic identification of ACTN1 accumulation","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO model combined with gain-of-function in cell line, multiple phenotypic readouts, corroborated in patient tissue (KBTBD13 patients)","pmids":["30990797"],"is_preprint":false},{"year":2021,"finding":"ACTN1 physically interacts with MOB1 (co-immunoprecipitation) and competitively inhibits MOB1 function, thereby decreasing phosphorylation of LATS1 and YAP, suppressing Hippo signaling, and promoting HCC tumor growth. The growth-promoting effect of ACTN1 was abrogated by pharmacological YAP inhibition.","method":"Co-immunoprecipitation; western blotting for p-LATS1 and p-YAP; ACTN1 knockdown in HCC cells; in vivo xenograft and intrahepatic transplantation models; pharmacological inhibition with verteporfin/super-TDU","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional rescue with pharmacological inhibition, in vitro and in vivo models, single lab","pmids":["33413564"],"is_preprint":false},{"year":2023,"finding":"ACTN1 promotes β-catenin signaling in HNSCC by (1) enhancing MYH9 interaction with GSK-3β leading to ubiquitin-dependent GSK-3β degradation, and (2) interacting with integrin β1 to activate the FAK/PI3K/AKT pathway. In addition, the β-catenin/c-Myc axis transcriptionally upregulates ACTN1, forming a positive feedback loop.","method":"Co-immunoprecipitation; IP-mass spectrometry; western blotting; dual-luciferase reporter assay; in vitro and in vivo (xenograft and patient-derived xenograft) models","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, IP-MS, luciferase reporter, and in vivo models in a single lab; multiple orthogonal methods","pmids":["38057867"],"is_preprint":false},{"year":2023,"finding":"ACTN1 physically interacts with integrin α5 (ITGA5) as shown by Co-IP, and this interaction promotes proliferation, invasion, migration, and EMT of HNSCC cells; ITGA5 overexpression rescues the suppressive effects of ACTN1 depletion.","method":"Co-immunoprecipitation; loss-of-function (siRNA knockdown) and rescue experiments; in vivo xenograft model","journal":"Iranian journal of basic medical sciences","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP plus epistasis-like rescue experiment, in vitro and in vivo; single lab","pmids":["36742137"],"is_preprint":false},{"year":2020,"finding":"Oroxylin A (OA) specifically binds ACTN1 and inhibits its expression in cancer-associated fibroblasts (CAFs), thereby decreasing phosphorylation of FAK and STAT3, and reducing secretion of CCL2, preventing CAF activation and breast cancer metastasis.","method":"Drug-target binding assay; western blotting; in vitro CAF activation assay; in vivo tumor metastasis model","journal":"Pharmacological research","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct binding claim plus functional downstream readouts in vitro and in vivo, single lab","pmids":["32492489"],"is_preprint":false},{"year":2011,"finding":"ACTN1 exists as part of a protein complex with FHL1 and PDLIM1, identified by tandem affinity purification from HEK-293 cells and verified by immunoprecipitation from mouse heart ventricles, with co-localization visualized in adult cardiomyocytes.","method":"Tandem affinity purification; LC-MS; immunoprecipitation from mouse heart ventricles; 3D fluorescence microscopy in cardiomyocytes","journal":"Molecular bioSystems","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity purification-MS validated by reciprocal IP in a physiologically relevant tissue, single lab","pmids":["21246116"],"is_preprint":false},{"year":2002,"finding":"ACTN1 undergoes brain-specific alternative splicing combining both smooth muscle (SM) and non-muscle (NM) exons into a novel brain-specific (BS) exon domain, expressed predominantly in adult brain neurons (hippocampus, cortex, caudate putamen), representing a distinct third isoform.","method":"RT-PCR; in situ hybridization in rat brain sections; developmental expression analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RT-PCR and in situ hybridization with developmental and regional characterization, single lab","pmids":["12099693"],"is_preprint":false},{"year":2023,"finding":"LLGL2 interacts with ACTN1 (identified by immunoprecipitation combined with mass spectrometry) and alters the intracellular localization and function of ACTN1 without changing its protein or mRNA levels, thereby impairing actin filament bundling and inhibiting ovarian cancer invasion and metastasis.","method":"Immunoprecipitation combined with mass spectrometry; LLGL2 overexpression/knockdown; in vitro migration and invasion assays; in vivo metastasis model","journal":"Cancers","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP-MS identification of interaction plus functional localization change and in vivo phenotype, single lab","pmids":["38136424"],"is_preprint":false},{"year":2025,"finding":"USP14 deubiquitinase stabilizes ACTN1 protein by removing its ubiquitin chains; pharmacological inhibition of USP14 reduces ACTN1 protein levels, impairs mesenchymal GBM phenotypes, and suppresses tumor progression in intracranial xenograft models.","method":"Ubiquitination assay; USP14 inhibition with IU1; western blotting; in vitro and intracranial xenograft in vivo models","journal":"Communications biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological and genetic manipulation with ubiquitination evidence and in vivo rescue, single lab","pmids":["41291211"],"is_preprint":false},{"year":2024,"finding":"miR-129-5p directly targets the 3'UTR of ACTN1, confirmed by luciferase reporter assay, reducing ACTN1 protein levels under anchorage-independent conditions and suppressing anchorage-independent growth in HPV-transformed keratinocytes.","method":"Luciferase reporter assay (3'UTR); RT-qPCR; miR-129-5p overexpression; anchorage-independent growth assay","journal":"Journal of medical virology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter validation plus functional growth assay, single lab with two orthogonal methods","pmids":["38566572"],"is_preprint":false},{"year":2025,"finding":"STAT5A (but not STAT5B) transcriptionally sustains ACTN1 expression; STAT5A knockout reduces ACTN1 levels, collapses F-actin architecture, and impairs mitochondrial morphology/DRP1 recruitment. Ectopic re-expression of ACTN1 in STAT5A-KO cells rescues actin cytoskeleton organization, mitochondrial network morphology, DNA damage, and IFN-β signaling, establishing ACTN1 as the key downstream effector of the STAT5A–actin–mitochondria axis.","method":"STAT5A/B knockout; ACTN1 ectopic overexpression rescue in KO background; live-cell imaging; mitochondrial morphology analysis; cGAS-STING/IFN signaling assays; ROS measurement","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with ectopic rescue using multiple orthogonal readouts; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2025.05.26.656095"],"is_preprint":true},{"year":2025,"finding":"ACTN1 localizes predominantly to focal adhesions in hiPSC-derived cardiomyocytes and is required for focal adhesion maturation and sarcomere assembly. siRNA depletion of ACTN1 disrupted Z-line formation and impaired sarcomere organization; rescue with exogenous ACTN1 but not ACTN2 restored these defects, revealing a non-redundant function. ACTN1 depletion reduced adhesion size, number, and stability of adhesion-associated vinculin.","method":"siRNA knockdown; live-cell imaging (vinculin/paxillin dynamics); immunofluorescence; exogenous rescue with ACTN1 vs ACTN2; hiPSC-derived cardiomyocytes","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA KD with isoform-specific rescue experiment and live-cell imaging, multiple orthogonal readouts; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2025.03.28.645933"],"is_preprint":true},{"year":2026,"finding":"PDLIM5 interacts with ACTN1/ACTN4 via its S593/F596 residues, promoting F-actin bundling and filopodia formation in tumor endothelial cells. Endothelial-specific deletion of Pdlim5 disrupts ACTN1/ACTN4-dependent F-actin bundling and impairs sprouting angiogenesis.","method":"Co-immunoprecipitation; endothelial-specific Pdlim5 knockout; filopodia and F-actin bundle imaging; in vivo tumor growth and vascular normalization assays","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain mapping (S593/F596) and in vivo genetic KO with defined cellular phenotype, single lab","pmids":["41605926"],"is_preprint":false},{"year":2026,"finding":"Lobetyolin (LBT) directly targets ACTN1 (chemical proteomics, molecular docking) and enhances ACTN1–F-actin affinity, promoting cortical actin organization and stabilizing intercellular junctions under inflammatory stress in pulmonary endothelial cells.","method":"Chemical proteomics (activity-based protein profiling); molecular docking; in vitro endothelial barrier assays; in vivo ALI mouse model; transcriptomics","journal":"Journal of ethnopharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — chemical proteomics with in vitro and in vivo validation, single lab; direct binding mechanistically supported","pmids":["42202915"],"is_preprint":false}],"current_model":"ACTN1 encodes α-actinin-1, a non-muscle actin-crosslinking protein that bundles F-actin through its actin-binding domain and assembles into antiparallel dimers via its rod domain; its protein levels are regulated by Cullin-3-mediated ubiquitin-dependent degradation (with USP14 acting as a stabilizing deubiquitinase) and by STAT5A-driven transcription; it localizes to focal adhesions in cardiomyocytes where it stabilizes adhesion maturation and is non-redundantly required for sarcomere assembly; it interacts with MOB1 to suppress Hippo/LATS1/YAP signaling, with integrin β1 to activate FAK/PI3K/AKT and β-catenin pathways, with MYH9 to promote GSK-3β degradation, with ITGA5 and PDLIM5 to regulate cytoskeletal architecture and angiogenesis, and with FHL1/PDLIM1 in a muscle complex; pathogenic mutations in any major domain (ABD, rod, or CaM) disorganize the actin cytoskeleton in megakaryocytes, reducing normal proplatelet formation and causing autosomal dominant macrothrombocytopenia."},"narrative":{"mechanistic_narrative":"ACTN1 encodes α-actinin-1, a non-muscle actin-crosslinking protein whose core function is to bundle and organize the F-actin cytoskeleton, an activity required for proper cellular architecture across megakaryocytes, cardiomyocytes, and endothelial cells [PMID:23434115, PMID:bio_10.1101_2025.03.28.645933, PMID:41605926]. Pathogenic missense mutations distributed across all major structural domains — the actin-binding domain (ABD), the spectrin-like rod repeats, and dimerization-relevant regions — disorganize the actin cytoskeleton, produce abnormal proplatelet formation in megakaryocytes, and cause autosomal dominant macrothrombocytopenia [PMID:23434115, PMID:24069336, PMID:26453073, PMID:31237726]. In cardiomyocytes ACTN1 localizes to focal adhesions and is non-redundantly required for focal adhesion maturation and sarcomere Z-line assembly, a function that ACTN2 cannot substitute [PMID:bio_10.1101_2025.03.28.645933]. ACTN1 abundance is tightly controlled at multiple levels: Cullin-3-mediated ubiquitin-dependent degradation limits its accumulation during myogenesis [PMID:30990797], the USP14 deubiquitinase stabilizes the protein by removing ubiquitin chains [PMID:41291211], STAT5A transcriptionally sustains its expression to maintain F-actin and mitochondrial architecture [PMID:bio_10.1101_2025.05.26.656095], and miR-129-5p represses it post-transcriptionally [PMID:38566572]. Beyond structural crosslinking, ACTN1 functions in signaling and tumor progression: it binds MOB1 to suppress Hippo/LATS1/YAP signaling [PMID:33413564], engages integrin β1 to activate FAK/PI3K/AKT and, via enhanced MYH9–GSK-3β interaction, drives β-catenin signaling in a c-Myc-coupled feedback loop [PMID:38057867], and partners with ITGA5 to promote proliferation and invasion [PMID:36742137]. Its actin-bundling activity is further modulated by interacting proteins including LLGL2, which alters its localization [PMID:38136424], and PDLIM5, which cooperates with ACTN1/ACTN4 to drive filopodia formation and sprouting angiogenesis [PMID:41605926].","teleology":[{"year":2013,"claim":"Established that ACTN1 mutations cause human disease by disrupting megakaryocyte cytoskeletal organization, answering how a cytoskeletal crosslinker links to platelet production defects.","evidence":"Transfection of ABD mutations in CHO cells and retroviral transduction of mouse fetal liver-derived megakaryocytes with morphological analysis of proplatelet formation","pmids":["23434115","24069336"],"confidence":"High","gaps":["Did not resolve which actin-bundling biophysical parameter is altered by each mutation","Restricted to ABD-domain mutations"]},{"year":2015,"claim":"Extended the disease mechanism beyond the ABD by showing rod-domain (SLR2) and dimerization-hindering mutations also disorganize actin, indicating multiple structural routes to loss of function.","evidence":"Immunofluorescence of transfected CHO cells and in vitro expression of rod-domain variants with actin network morphology analysis","pmids":["26453073","31237726"],"confidence":"Medium","gaps":["Single-method (IF) for some variants","Quantitative biophysical effect on dimerization not directly measured"]},{"year":2002,"claim":"Revealed isoform diversity by identifying a brain-specific ACTN1 splice variant, raising the question of tissue-specific cytoskeletal functions.","evidence":"RT-PCR and in situ hybridization in rat brain with developmental and regional expression analysis","pmids":["12099693"],"confidence":"Medium","gaps":["Functional role of the brain-specific isoform not determined","No binding-partner or activity data for this isoform"]},{"year":2011,"claim":"Placed ACTN1 in a defined muscle-associated complex with FHL1 and PDLIM1, establishing physical partnerships in cardiac tissue.","evidence":"Tandem affinity purification with LC-MS, reciprocal IP from mouse heart ventricles, and 3D fluorescence microscopy in cardiomyocytes","pmids":["21246116"],"confidence":"Medium","gaps":["Functional consequence of the complex not tested","Stoichiometry and direct binary contacts unresolved"]},{"year":2019,"claim":"Showed that ACTN1 protein levels must be actively restrained, identifying Cullin-3-mediated degradation as essential for myogenesis and neuromuscular junction development.","evidence":"Cullin-3 knockout mice, C2C12 overexpression with fusion and acetylcholine receptor clustering assays, and proteomic detection of ACTN1 accumulation","pmids":["30990797"],"confidence":"High","gaps":["Direct E3-substrate ubiquitination biochemistry not fully reconstituted","Adaptor selecting ACTN1 within Cullin-3 complex not defined"]},{"year":2021,"claim":"Connected ACTN1 to growth-control signaling by showing it binds MOB1 to suppress Hippo/LATS1/YAP and promote tumor growth.","evidence":"Co-IP, p-LATS1/p-YAP western blotting, ACTN1 knockdown in HCC cells, xenograft models, and YAP pharmacological inhibition rescue","pmids":["33413564"],"confidence":"Medium","gaps":["Single lab without reciprocal in vivo genetic validation","Whether actin-bundling activity is required for MOB1 inhibition unknown"]},{"year":2023,"claim":"Defined ACTN1 as a node in oncogenic adhesion/Wnt signaling via integrin β1/FAK/PI3K/AKT, MYH9-dependent GSK-3β degradation driving β-catenin, and an ITGA5-dependent invasion axis.","evidence":"Reciprocal Co-IP, IP-mass spectrometry, dual-luciferase reporter, siRNA rescue, and xenograft/patient-derived xenograft models in HNSCC","pmids":["38057867","36742137"],"confidence":"Medium","gaps":["Multiple signaling claims rest on single-lab data","Direct versus indirect nature of ACTN1–GSK-3β coupling not separated"]},{"year":2024,"claim":"Added post-transcriptional control by demonstrating miR-129-5p directly represses ACTN1 to limit anchorage-independent growth.","evidence":"3'UTR luciferase reporter, RT-qPCR, miR-129-5p overexpression, and anchorage-independent growth assay in HPV-transformed keratinocytes","pmids":["38566572"],"confidence":"Medium","gaps":["In vivo relevance of the miRNA-ACTN1 axis untested","Single cellular context"]},{"year":2023,"claim":"Showed ACTN1 function can be modulated by localization rather than abundance, with LLGL2 redirecting ACTN1 to impair actin bundling and suppress ovarian cancer invasion.","evidence":"IP-mass spectrometry, LLGL2 overexpression/knockdown, migration/invasion assays, and in vivo metastasis model","pmids":["38136424"],"confidence":"Medium","gaps":["Mechanism by which LLGL2 relocalizes ACTN1 unresolved","Direct binding interface not mapped"]},{"year":2025,"claim":"Identified USP14 as the stabilizing deubiquitinase counterbalancing ACTN1 degradation, tying ACTN1 abundance to mesenchymal glioblastoma phenotypes.","evidence":"Ubiquitination assay, USP14 inhibition with IU1, western blotting, and intracranial xenograft models","pmids":["41291211"],"confidence":"Medium","gaps":["Direct USP14–ACTN1 binding not biochemically reconstituted","Relationship to Cullin-3 pathway not co-analyzed"]},{"year":2025,"claim":"Positioned ACTN1 as the downstream effector of a STAT5A–actin–mitochondria axis, linking transcriptional control to cytoskeletal and mitochondrial integrity.","evidence":"STAT5A/B knockout with ACTN1 ectopic rescue, live-cell imaging, mitochondrial morphology, DRP1 recruitment, and cGAS-STING/IFN assays (preprint)","pmids":["bio_10.1101_2025.05.26.656095"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Direct STAT5A binding to the ACTN1 promoter not shown"]},{"year":2025,"claim":"Demonstrated non-redundant ACTN1 function at cardiomyocyte focal adhesions required for sarcomere assembly, distinguishing it from ACTN2.","evidence":"siRNA knockdown, vinculin/paxillin live-cell imaging, and isoform-specific rescue with ACTN1 versus ACTN2 in hiPSC-derived cardiomyocytes (preprint)","pmids":["bio_10.1101_2025.03.28.645933"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Molecular basis for ACTN1 vs ACTN2 non-redundancy undefined"]},{"year":2026,"claim":"Showed PDLIM5 cooperates with ACTN1/ACTN4 to drive F-actin bundling, filopodia formation, and sprouting angiogenesis, defining a partner that activates ACTN1's bundling function.","evidence":"Co-IP with domain mapping (PDLIM5 S593/F596), endothelial-specific Pdlim5 knockout, filopodia/F-actin imaging, and in vivo tumor vascular assays","pmids":["41605926"],"confidence":"Medium","gaps":["Direct ACTN1 contribution not separated from ACTN4","Whether PDLIM5 alters bundling kinetics biophysically untested"]},{"year":2026,"claim":"Established ACTN1 as a druggable target whose enhanced F-actin affinity stabilizes endothelial junctions, identifying lobetyolin as a direct binder.","evidence":"Chemical proteomics, molecular docking, endothelial barrier assays, and an in vivo acute lung injury mouse model","pmids":["42202915"],"confidence":"Medium","gaps":["Binding site on ACTN1 not crystallographically defined","Selectivity over ACTN4 not established"]},{"year":null,"claim":"How the multiple abundance-control pathways (Cullin-3, USP14, STAT5A, miR-129-5p) are integrated, and whether ACTN1's signaling roles depend on or are separable from its actin-bundling activity, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking degradation, stabilization, and transcriptional control","Structure-function separation of crosslinking versus signaling not addressed","No high-resolution structure of mutant ACTN1 explaining domain-specific cytoskeletal failure"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,15,16,17]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[5,6,9,16]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[0,2,3,15]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[15]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5,6,7]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,1,2,3]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[4,12]}],"complexes":["FHL1/PDLIM1 muscle complex","focal adhesion"],"partners":["MOB1","ITGB1","MYH9","ITGA5","FHL1","PDLIM1","LLGL2","PDLIM5"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P12814","full_name":"Alpha-actinin-1","aliases":["Alpha-actinin cytoskeletal isoform","F-actin cross-linking protein","Non-muscle alpha-actinin-1"],"length_aa":892,"mass_kda":103.1,"function":"F-actin cross-linking protein which is thought to anchor actin to a variety of intracellular structures. Association with IGSF8 regulates the immune synapse formation and is required for efficient T-cell activation (PubMed:22689882)","subcellular_location":"Cytoplasm, cytoskeleton; Cytoplasm, myofibril, sarcomere, Z line; Cell membrane; Cell junction; Cell projection, ruffle","url":"https://www.uniprot.org/uniprotkb/P12814/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ACTN1","classification":"Not Classified","n_dependent_lines":17,"n_total_lines":1208,"dependency_fraction":0.014072847682119206},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000072110","cell_line_id":"CID001711","localizations":[{"compartment":"cytoskeleton","grade":3},{"compartment":"membrane","grade":3}],"interactors":[{"gene":"ACTN4","stoichiometry":10.0},{"gene":"CAAP1","stoichiometry":0.2},{"gene":"RELA","stoichiometry":0.2},{"gene":"TOP3B","stoichiometry":0.2},{"gene":"C14ORF119","stoichiometry":0.2},{"gene":"GSPT1","stoichiometry":0.2},{"gene":"INPPL1","stoichiometry":0.2},{"gene":"SAR1B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001711","total_profiled":1310},"omim":[{"mim_id":"620912","title":"MICAL-LIKE PROTEIN 2; MICALL2","url":"https://www.omim.org/entry/620912"},{"mim_id":"620475","title":"THROMBOCYTOPENIA 8, WITH DYSMORPHIC FEATURES AND DEVELOPMENTAL DELAY; THC8","url":"https://www.omim.org/entry/620475"},{"mim_id":"615193","title":"BLEEDING DISORDER, PLATELET-TYPE, 15; BDPLT15","url":"https://www.omim.org/entry/615193"},{"mim_id":"610861","title":"SPECTRIN REPEAT-CONTAINING NUCLEAR ENVELOPE PROTEIN 3; SYNE3","url":"https://www.omim.org/entry/610861"},{"mim_id":"610586","title":"RHO GTPase-ACTIVATING PROTEIN 24; ARHGAP24","url":"https://www.omim.org/entry/610586"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Actin filaments","reliability":"Approved"},{"location":"Focal adhesion sites","reliability":"Approved"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Primary cilium transition zone","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"smooth muscle","ntpm":499.3}],"url":"https://www.proteinatlas.org/search/ACTN1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P12814","domains":[{"cath_id":"1.10.418.10","chopping":"27-136","consensus_level":"high","plddt":88.6591,"start":27,"end":136},{"cath_id":"1.10.418.10","chopping":"146-233","consensus_level":"high","plddt":90.3839,"start":146,"end":233},{"cath_id":"1.20.58.60","chopping":"506-740","consensus_level":"medium","plddt":87.5442,"start":506,"end":740},{"cath_id":"1.10.238.10","chopping":"825-886","consensus_level":"medium","plddt":85.4942,"start":825,"end":886}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P12814","model_url":"https://alphafold.ebi.ac.uk/files/AF-P12814-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P12814-F1-predicted_aligned_error_v6.png","plddt_mean":85.25},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ACTN1","jax_strain_url":"https://www.jax.org/strain/search?query=ACTN1"},"sequence":{"accession":"P12814","fasta_url":"https://rest.uniprot.org/uniprotkb/P12814.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P12814/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P12814"}},"corpus_meta":[{"pmid":"23434115","id":"PMC_23434115","title":"ACTN1 mutations cause congenital macrothrombocytopenia.","date":"2013","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23434115","citation_count":159,"is_preprint":false},{"pmid":"25361813","id":"PMC_25361813","title":"ACTN1-related thrombocytopenia: identification of novel families for phenotypic characterization.","date":"2014","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/25361813","citation_count":48,"is_preprint":false},{"pmid":"32492489","id":"PMC_32492489","title":"Oroxylin A suppresses ACTN1 expression to inactivate cancer-associated fibroblasts and restrain breast cancer metastasis.","date":"2020","source":"Pharmacological research","url":"https://pubmed.ncbi.nlm.nih.gov/32492489","citation_count":46,"is_preprint":false},{"pmid":"33413564","id":"PMC_33413564","title":"ACTN1 supports tumor growth by inhibiting Hippo signaling in hepatocellular carcinoma.","date":"2021","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/33413564","citation_count":42,"is_preprint":false},{"pmid":"24069336","id":"PMC_24069336","title":"A missense mutation in the alpha-actinin 1 gene (ACTN1) is the cause of autosomal dominant macrothrombocytopenia in a large French family.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24069336","citation_count":41,"is_preprint":false},{"pmid":"38057867","id":"PMC_38057867","title":"ACTN1 promotes HNSCC tumorigenesis and cisplatin resistance by enhancing MYH9-dependent degradation of GSK-3β and integrin β1-mediated phosphorylation of FAK.","date":"2023","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/38057867","citation_count":31,"is_preprint":false},{"pmid":"12099693","id":"PMC_12099693","title":"Brain-specific splicing of alpha-actinin 1 (ACTN1) mRNA.","date":"2002","source":"Biochemical and biophysical research 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organization and platelet biogenesis.\",\n      \"method\": \"In vitro transfection in CHO cells; retroviral transduction of mouse fetal liver-derived megakaryocytes; immunofluorescence; morphological analysis of proplatelet formation\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function in two independent cellular systems (CHO and primary megakaryocytes) with defined phenotypic readouts, replicated across multiple mutation-bearing families\",\n      \"pmids\": [\"23434115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"A missense mutation (p.Arg46Gln) in the actin-binding domain of ACTN1 causes disorganization of the cellular cytoplasm in transfected COS-7 cells, as observed by immunofluorescence, and disorganized megakaryocyte ultrastructure by electron microscopy.\",\n      \"method\": \"Immunofluorescence in transfected COS-7 cells; electron microscopy of cultured mutation-harboring megakaryocytes\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal methods (IF and EM) in a single lab studying a disease-associated mutation in the functionally critical ABD\",\n      \"pmids\": [\"24069336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"An ACTN1 mutation in the spectrin-like repeat 2 (SLR2) rod domain (p.Leu395Gln), outside the ABD and CaM domains, also causes disorganization of the actin cytoskeleton in CHO cells, demonstrating that rod domain mutations can disrupt ACTN1 cytoskeletal function.\",\n      \"method\": \"Immunofluorescence in transfected CHO cells\",\n      \"journal\": \"Annals of hematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single method (IF) but consistent with mechanistic findings from multiple prior studies of ABD/CaM mutations\",\n      \"pmids\": [\"26453073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Rod domain ACTN1 variants predicted to hinder dimer formation cause actin network disorganization and increased thickness of actin fibers when expressed in vitro, extending the spectrum of ACTN1 structural domains whose mutation disrupts cytoskeletal function.\",\n      \"method\": \"In vitro expression of ACTN1 variants; actin network morphology analysis\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single method but assessed multiple novel variants, consistent across the cohort\",\n      \"pmids\": [\"31237726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Cullin-3 E3-ubiquitin ligase mediates degradation of ACTN1 during myogenesis; loss of Cullin-3 causes accumulation of ACTN1 in muscle. Overexpression of ACTN1 in C2C12 myoblasts triggers defects in fusion, myogenesis, and acetylcholine receptor clustering, establishing that Cullin-3-dependent regulation of ACTN1 protein levels is essential for normal muscle and neuromuscular junction development.\",\n      \"method\": \"Cullin-3 knockout mice; C2C12 myoblast overexpression; immunofluorescence; acetylcholine receptor clustering assay; proteomic identification of ACTN1 accumulation\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO model combined with gain-of-function in cell line, multiple phenotypic readouts, corroborated in patient tissue (KBTBD13 patients)\",\n      \"pmids\": [\"30990797\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ACTN1 physically interacts with MOB1 (co-immunoprecipitation) and competitively inhibits MOB1 function, thereby decreasing phosphorylation of LATS1 and YAP, suppressing Hippo signaling, and promoting HCC tumor growth. The growth-promoting effect of ACTN1 was abrogated by pharmacological YAP inhibition.\",\n      \"method\": \"Co-immunoprecipitation; western blotting for p-LATS1 and p-YAP; ACTN1 knockdown in HCC cells; in vivo xenograft and intrahepatic transplantation models; pharmacological inhibition with verteporfin/super-TDU\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional rescue with pharmacological inhibition, in vitro and in vivo models, single lab\",\n      \"pmids\": [\"33413564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ACTN1 promotes β-catenin signaling in HNSCC by (1) enhancing MYH9 interaction with GSK-3β leading to ubiquitin-dependent GSK-3β degradation, and (2) interacting with integrin β1 to activate the FAK/PI3K/AKT pathway. In addition, the β-catenin/c-Myc axis transcriptionally upregulates ACTN1, forming a positive feedback loop.\",\n      \"method\": \"Co-immunoprecipitation; IP-mass spectrometry; western blotting; dual-luciferase reporter assay; in vitro and in vivo (xenograft and patient-derived xenograft) models\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, IP-MS, luciferase reporter, and in vivo models in a single lab; multiple orthogonal methods\",\n      \"pmids\": [\"38057867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ACTN1 physically interacts with integrin α5 (ITGA5) as shown by Co-IP, and this interaction promotes proliferation, invasion, migration, and EMT of HNSCC cells; ITGA5 overexpression rescues the suppressive effects of ACTN1 depletion.\",\n      \"method\": \"Co-immunoprecipitation; loss-of-function (siRNA knockdown) and rescue experiments; in vivo xenograft model\",\n      \"journal\": \"Iranian journal of basic medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP plus epistasis-like rescue experiment, in vitro and in vivo; single lab\",\n      \"pmids\": [\"36742137\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Oroxylin A (OA) specifically binds ACTN1 and inhibits its expression in cancer-associated fibroblasts (CAFs), thereby decreasing phosphorylation of FAK and STAT3, and reducing secretion of CCL2, preventing CAF activation and breast cancer metastasis.\",\n      \"method\": \"Drug-target binding assay; western blotting; in vitro CAF activation assay; in vivo tumor metastasis model\",\n      \"journal\": \"Pharmacological research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct binding claim plus functional downstream readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"32492489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ACTN1 exists as part of a protein complex with FHL1 and PDLIM1, identified by tandem affinity purification from HEK-293 cells and verified by immunoprecipitation from mouse heart ventricles, with co-localization visualized in adult cardiomyocytes.\",\n      \"method\": \"Tandem affinity purification; LC-MS; immunoprecipitation from mouse heart ventricles; 3D fluorescence microscopy in cardiomyocytes\",\n      \"journal\": \"Molecular bioSystems\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity purification-MS validated by reciprocal IP in a physiologically relevant tissue, single lab\",\n      \"pmids\": [\"21246116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ACTN1 undergoes brain-specific alternative splicing combining both smooth muscle (SM) and non-muscle (NM) exons into a novel brain-specific (BS) exon domain, expressed predominantly in adult brain neurons (hippocampus, cortex, caudate putamen), representing a distinct third isoform.\",\n      \"method\": \"RT-PCR; in situ hybridization in rat brain sections; developmental expression analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RT-PCR and in situ hybridization with developmental and regional characterization, single lab\",\n      \"pmids\": [\"12099693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LLGL2 interacts with ACTN1 (identified by immunoprecipitation combined with mass spectrometry) and alters the intracellular localization and function of ACTN1 without changing its protein or mRNA levels, thereby impairing actin filament bundling and inhibiting ovarian cancer invasion and metastasis.\",\n      \"method\": \"Immunoprecipitation combined with mass spectrometry; LLGL2 overexpression/knockdown; in vitro migration and invasion assays; in vivo metastasis model\",\n      \"journal\": \"Cancers\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP-MS identification of interaction plus functional localization change and in vivo phenotype, single lab\",\n      \"pmids\": [\"38136424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"USP14 deubiquitinase stabilizes ACTN1 protein by removing its ubiquitin chains; pharmacological inhibition of USP14 reduces ACTN1 protein levels, impairs mesenchymal GBM phenotypes, and suppresses tumor progression in intracranial xenograft models.\",\n      \"method\": \"Ubiquitination assay; USP14 inhibition with IU1; western blotting; in vitro and intracranial xenograft in vivo models\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological and genetic manipulation with ubiquitination evidence and in vivo rescue, single lab\",\n      \"pmids\": [\"41291211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"miR-129-5p directly targets the 3'UTR of ACTN1, confirmed by luciferase reporter assay, reducing ACTN1 protein levels under anchorage-independent conditions and suppressing anchorage-independent growth in HPV-transformed keratinocytes.\",\n      \"method\": \"Luciferase reporter assay (3'UTR); RT-qPCR; miR-129-5p overexpression; anchorage-independent growth assay\",\n      \"journal\": \"Journal of medical virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter validation plus functional growth assay, single lab with two orthogonal methods\",\n      \"pmids\": [\"38566572\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"STAT5A (but not STAT5B) transcriptionally sustains ACTN1 expression; STAT5A knockout reduces ACTN1 levels, collapses F-actin architecture, and impairs mitochondrial morphology/DRP1 recruitment. Ectopic re-expression of ACTN1 in STAT5A-KO cells rescues actin cytoskeleton organization, mitochondrial network morphology, DNA damage, and IFN-β signaling, establishing ACTN1 as the key downstream effector of the STAT5A–actin–mitochondria axis.\",\n      \"method\": \"STAT5A/B knockout; ACTN1 ectopic overexpression rescue in KO background; live-cell imaging; mitochondrial morphology analysis; cGAS-STING/IFN signaling assays; ROS measurement\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with ectopic rescue using multiple orthogonal readouts; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.05.26.656095\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ACTN1 localizes predominantly to focal adhesions in hiPSC-derived cardiomyocytes and is required for focal adhesion maturation and sarcomere assembly. siRNA depletion of ACTN1 disrupted Z-line formation and impaired sarcomere organization; rescue with exogenous ACTN1 but not ACTN2 restored these defects, revealing a non-redundant function. ACTN1 depletion reduced adhesion size, number, and stability of adhesion-associated vinculin.\",\n      \"method\": \"siRNA knockdown; live-cell imaging (vinculin/paxillin dynamics); immunofluorescence; exogenous rescue with ACTN1 vs ACTN2; hiPSC-derived cardiomyocytes\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA KD with isoform-specific rescue experiment and live-cell imaging, multiple orthogonal readouts; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.03.28.645933\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"PDLIM5 interacts with ACTN1/ACTN4 via its S593/F596 residues, promoting F-actin bundling and filopodia formation in tumor endothelial cells. Endothelial-specific deletion of Pdlim5 disrupts ACTN1/ACTN4-dependent F-actin bundling and impairs sprouting angiogenesis.\",\n      \"method\": \"Co-immunoprecipitation; endothelial-specific Pdlim5 knockout; filopodia and F-actin bundle imaging; in vivo tumor growth and vascular normalization assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain mapping (S593/F596) and in vivo genetic KO with defined cellular phenotype, single lab\",\n      \"pmids\": [\"41605926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Lobetyolin (LBT) directly targets ACTN1 (chemical proteomics, molecular docking) and enhances ACTN1–F-actin affinity, promoting cortical actin organization and stabilizing intercellular junctions under inflammatory stress in pulmonary endothelial cells.\",\n      \"method\": \"Chemical proteomics (activity-based protein profiling); molecular docking; in vitro endothelial barrier assays; in vivo ALI mouse model; transcriptomics\",\n      \"journal\": \"Journal of ethnopharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — chemical proteomics with in vitro and in vivo validation, single lab; direct binding mechanistically supported\",\n      \"pmids\": [\"42202915\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ACTN1 encodes α-actinin-1, a non-muscle actin-crosslinking protein that bundles F-actin through its actin-binding domain and assembles into antiparallel dimers via its rod domain; its protein levels are regulated by Cullin-3-mediated ubiquitin-dependent degradation (with USP14 acting as a stabilizing deubiquitinase) and by STAT5A-driven transcription; it localizes to focal adhesions in cardiomyocytes where it stabilizes adhesion maturation and is non-redundantly required for sarcomere assembly; it interacts with MOB1 to suppress Hippo/LATS1/YAP signaling, with integrin β1 to activate FAK/PI3K/AKT and β-catenin pathways, with MYH9 to promote GSK-3β degradation, with ITGA5 and PDLIM5 to regulate cytoskeletal architecture and angiogenesis, and with FHL1/PDLIM1 in a muscle complex; pathogenic mutations in any major domain (ABD, rod, or CaM) disorganize the actin cytoskeleton in megakaryocytes, reducing normal proplatelet formation and causing autosomal dominant macrothrombocytopenia.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ACTN1 encodes α-actinin-1, a non-muscle actin-crosslinking protein whose core function is to bundle and organize the F-actin cytoskeleton, an activity required for proper cellular architecture across megakaryocytes, cardiomyocytes, and endothelial cells [#0, #15, #16]. Pathogenic missense mutations distributed across all major structural domains — the actin-binding domain (ABD), the spectrin-like rod repeats, and dimerization-relevant regions — disorganize the actin cytoskeleton, produce abnormal proplatelet formation in megakaryocytes, and cause autosomal dominant macrothrombocytopenia [#0, #1, #2, #3]. In cardiomyocytes ACTN1 localizes to focal adhesions and is non-redundantly required for focal adhesion maturation and sarcomere Z-line assembly, a function that ACTN2 cannot substitute [#15]. ACTN1 abundance is tightly controlled at multiple levels: Cullin-3-mediated ubiquitin-dependent degradation limits its accumulation during myogenesis [#4], the USP14 deubiquitinase stabilizes the protein by removing ubiquitin chains [#12], STAT5A transcriptionally sustains its expression to maintain F-actin and mitochondrial architecture [#14], and miR-129-5p represses it post-transcriptionally [#13]. Beyond structural crosslinking, ACTN1 functions in signaling and tumor progression: it binds MOB1 to suppress Hippo/LATS1/YAP signaling [#5], engages integrin β1 to activate FAK/PI3K/AKT and, via enhanced MYH9–GSK-3β interaction, drives β-catenin signaling in a c-Myc-coupled feedback loop [#6], and partners with ITGA5 to promote proliferation and invasion [#7]. Its actin-bundling activity is further modulated by interacting proteins including LLGL2, which alters its localization [#11], and PDLIM5, which cooperates with ACTN1/ACTN4 to drive filopodia formation and sprouting angiogenesis [#16].\",\n  \"teleology\": [\n    {\n      \"year\": 2013,\n      \"claim\": \"Established that ACTN1 mutations cause human disease by disrupting megakaryocyte cytoskeletal organization, answering how a cytoskeletal crosslinker links to platelet production defects.\",\n      \"evidence\": \"Transfection of ABD mutations in CHO cells and retroviral transduction of mouse fetal liver-derived megakaryocytes with morphological analysis of proplatelet formation\",\n      \"pmids\": [\"23434115\", \"24069336\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which actin-bundling biophysical parameter is altered by each mutation\", \"Restricted to ABD-domain mutations\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Extended the disease mechanism beyond the ABD by showing rod-domain (SLR2) and dimerization-hindering mutations also disorganize actin, indicating multiple structural routes to loss of function.\",\n      \"evidence\": \"Immunofluorescence of transfected CHO cells and in vitro expression of rod-domain variants with actin network morphology analysis\",\n      \"pmids\": [\"26453073\", \"31237726\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-method (IF) for some variants\", \"Quantitative biophysical effect on dimerization not directly measured\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Revealed isoform diversity by identifying a brain-specific ACTN1 splice variant, raising the question of tissue-specific cytoskeletal functions.\",\n      \"evidence\": \"RT-PCR and in situ hybridization in rat brain with developmental and regional expression analysis\",\n      \"pmids\": [\"12099693\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of the brain-specific isoform not determined\", \"No binding-partner or activity data for this isoform\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed ACTN1 in a defined muscle-associated complex with FHL1 and PDLIM1, establishing physical partnerships in cardiac tissue.\",\n      \"evidence\": \"Tandem affinity purification with LC-MS, reciprocal IP from mouse heart ventricles, and 3D fluorescence microscopy in cardiomyocytes\",\n      \"pmids\": [\"21246116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the complex not tested\", \"Stoichiometry and direct binary contacts unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed that ACTN1 protein levels must be actively restrained, identifying Cullin-3-mediated degradation as essential for myogenesis and neuromuscular junction development.\",\n      \"evidence\": \"Cullin-3 knockout mice, C2C12 overexpression with fusion and acetylcholine receptor clustering assays, and proteomic detection of ACTN1 accumulation\",\n      \"pmids\": [\"30990797\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct E3-substrate ubiquitination biochemistry not fully reconstituted\", \"Adaptor selecting ACTN1 within Cullin-3 complex not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Connected ACTN1 to growth-control signaling by showing it binds MOB1 to suppress Hippo/LATS1/YAP and promote tumor growth.\",\n      \"evidence\": \"Co-IP, p-LATS1/p-YAP western blotting, ACTN1 knockdown in HCC cells, xenograft models, and YAP pharmacological inhibition rescue\",\n      \"pmids\": [\"33413564\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab without reciprocal in vivo genetic validation\", \"Whether actin-bundling activity is required for MOB1 inhibition unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined ACTN1 as a node in oncogenic adhesion/Wnt signaling via integrin β1/FAK/PI3K/AKT, MYH9-dependent GSK-3β degradation driving β-catenin, and an ITGA5-dependent invasion axis.\",\n      \"evidence\": \"Reciprocal Co-IP, IP-mass spectrometry, dual-luciferase reporter, siRNA rescue, and xenograft/patient-derived xenograft models in HNSCC\",\n      \"pmids\": [\"38057867\", \"36742137\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Multiple signaling claims rest on single-lab data\", \"Direct versus indirect nature of ACTN1–GSK-3β coupling not separated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Added post-transcriptional control by demonstrating miR-129-5p directly represses ACTN1 to limit anchorage-independent growth.\",\n      \"evidence\": \"3'UTR luciferase reporter, RT-qPCR, miR-129-5p overexpression, and anchorage-independent growth assay in HPV-transformed keratinocytes\",\n      \"pmids\": [\"38566572\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo relevance of the miRNA-ACTN1 axis untested\", \"Single cellular context\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed ACTN1 function can be modulated by localization rather than abundance, with LLGL2 redirecting ACTN1 to impair actin bundling and suppress ovarian cancer invasion.\",\n      \"evidence\": \"IP-mass spectrometry, LLGL2 overexpression/knockdown, migration/invasion assays, and in vivo metastasis model\",\n      \"pmids\": [\"38136424\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which LLGL2 relocalizes ACTN1 unresolved\", \"Direct binding interface not mapped\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified USP14 as the stabilizing deubiquitinase counterbalancing ACTN1 degradation, tying ACTN1 abundance to mesenchymal glioblastoma phenotypes.\",\n      \"evidence\": \"Ubiquitination assay, USP14 inhibition with IU1, western blotting, and intracranial xenograft models\",\n      \"pmids\": [\"41291211\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct USP14–ACTN1 binding not biochemically reconstituted\", \"Relationship to Cullin-3 pathway not co-analyzed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Positioned ACTN1 as the downstream effector of a STAT5A–actin–mitochondria axis, linking transcriptional control to cytoskeletal and mitochondrial integrity.\",\n      \"evidence\": \"STAT5A/B knockout with ACTN1 ectopic rescue, live-cell imaging, mitochondrial morphology, DRP1 recruitment, and cGAS-STING/IFN assays (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.05.26.656095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Direct STAT5A binding to the ACTN1 promoter not shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Demonstrated non-redundant ACTN1 function at cardiomyocyte focal adhesions required for sarcomere assembly, distinguishing it from ACTN2.\",\n      \"evidence\": \"siRNA knockdown, vinculin/paxillin live-cell imaging, and isoform-specific rescue with ACTN1 versus ACTN2 in hiPSC-derived cardiomyocytes (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.03.28.645933\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Molecular basis for ACTN1 vs ACTN2 non-redundancy undefined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Showed PDLIM5 cooperates with ACTN1/ACTN4 to drive F-actin bundling, filopodia formation, and sprouting angiogenesis, defining a partner that activates ACTN1's bundling function.\",\n      \"evidence\": \"Co-IP with domain mapping (PDLIM5 S593/F596), endothelial-specific Pdlim5 knockout, filopodia/F-actin imaging, and in vivo tumor vascular assays\",\n      \"pmids\": [\"41605926\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ACTN1 contribution not separated from ACTN4\", \"Whether PDLIM5 alters bundling kinetics biophysically untested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Established ACTN1 as a druggable target whose enhanced F-actin affinity stabilizes endothelial junctions, identifying lobetyolin as a direct binder.\",\n      \"evidence\": \"Chemical proteomics, molecular docking, endothelial barrier assays, and an in vivo acute lung injury mouse model\",\n      \"pmids\": [\"42202915\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding site on ACTN1 not crystallographically defined\", \"Selectivity over ACTN4 not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the multiple abundance-control pathways (Cullin-3, USP14, STAT5A, miR-129-5p) are integrated, and whether ACTN1's signaling roles depend on or are separable from its actin-bundling activity, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking degradation, stabilization, and transcriptional control\", \"Structure-function separation of crosslinking versus signaling not addressed\", \"No high-resolution structure of mutant ACTN1 explaining domain-specific cytoskeletal failure\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 15, 16, 17]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [5, 6, 9, 16]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [0, 2, 3, 15]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5, 6, 7]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 1, 2, 3]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [4, 12]}\n    ],\n    \"complexes\": [\n      \"FHL1/PDLIM1 muscle complex\",\n      \"focal adhesion\"\n    ],\n    \"partners\": [\n      \"MOB1\",\n      \"ITGB1\",\n      \"MYH9\",\n      \"ITGA5\",\n      \"FHL1\",\n      \"PDLIM1\",\n      \"LLGL2\",\n      \"PDLIM5\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":5,"faith_total":5,"faith_pct":100.0}}