{"gene":"FGF12","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2013,"finding":"FGF12-B (the major FHF expressed in human ventricle) binds the NaV1.5 C-terminus; the BrS-associated missense mutation Q7R-FGF12 reduces this binding and decreases Na+ channel current density and availability in adult rat cardiomyocytes, reducing action potential amplitude without affecting Ca2+ channel function.","method":"Biochemical binding assays (Co-IP/pulldown of NaV1.5 C-terminus), whole-cell voltage-clamp in adult rat ventricular cardiomyocytes expressing wild-type or mutant FGF12-B via FHF-swap system, action potential recordings","journal":"Heart rhythm","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal binding assay plus electrophysiology in native cardiomyocytes with functional phenotype (Na+ current, action potential), single lab but multiple orthogonal methods","pmids":["24096171"],"is_preprint":false},{"year":2016,"finding":"A gain-of-function de novo missense mutation in FHF1/FGF12 (p.Arg52His) enhances depolarizing shifts in Nav1.6 voltage-dependent fast inactivation in Neuro2A cells, predicting increased neuronal excitability; this gain-of-function effect arises from weaker interaction of mutant FHF1 with the Nav cytoplasmic tail. Transgenic overexpression of mutant FHF1B in zebrafish larvae enhanced epileptiform discharges.","method":"Whole-cell patch-clamp electrophysiology in transfected Neuro2A cells, in vivo zebrafish epilepsy model with transgenic overexpression","journal":"Neurology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vitro electrophysiology plus in vivo zebrafish model, single lab but two orthogonal methods with clear mechanistic readout","pmids":["27164707"],"is_preprint":false},{"year":2011,"finding":"FGF12 is internalized into intestinal epithelial cell cytoplasm through two cell-penetrating peptide (CPP) domains: CPP-M (internal, common to FGF family) and CPP-C (~10 aa, C-terminal residues 140–149, unique to FGF12 subfamily). Mutation E142L in CPP-C drastically reduces internalization. Internalized exogenous FGF12 inhibits radiation-induced apoptosis in vivo (BALB/c mice), and deletion of CPP-C reduces this anti-apoptotic effect.","method":"Recombinant protein internalization assay in IEC6 cells, site-directed mutagenesis of CPP-C domain, chimeric FGF1/CPP-C protein internalization, in vivo intraperitoneal injection in BALB/c mice with apoptosis quantification","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mutagenesis of functional domain combined with in vitro and in vivo functional readout in single lab, multiple orthogonal methods","pmids":["21518765"],"is_preprint":false},{"year":2008,"finding":"Intracellular FGF12 suppresses radiation-induced apoptosis in mast cells (HMC-1) via the MEK/ERK pathway; overexpression of FGF12 blocked the augmentation of apoptosis caused by MEK/ERK inhibitor PD98059. This anti-apoptotic effect was independent of the MAPK scaffold protein IB2 (which binds FGF12 but did not interfere with the anti-apoptotic effect).","method":"Overexpression and siRNA knockdown of FGF12 in HMC-1 cells, pharmacological inhibition of MEK/ERK with PD98059, apoptosis assay","journal":"Journal of radiation research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean KD/OE with defined cellular phenotype and pathway placement via pharmacological inhibitor, single lab single study","pmids":["18525161"],"is_preprint":false},{"year":2020,"finding":"FGF12 directly interacts with all four major FGFRs (FGFR1–4), causing efficient FGFR activation and initiation of receptor-dependent signaling cascades. Extracellular FHF1/FGF12 protects cells from apoptosis but is unable to stimulate cell division, distinguishing it biologically from canonical FGFs.","method":"Direct binding assays (pulldown/Co-IP), FGFR phosphorylation assays, cell viability and apoptosis assays","journal":"Cell communication and signaling : CCS","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct binding plus receptor activation plus functional apoptosis readout, single lab","pmids":["32357892"],"is_preprint":false},{"year":2020,"finding":"FGF12 is required for BMP-mediated acquisition of quiescent/differentiated pulmonary arterial smooth muscle cell (PASMC) phenotype. Mechanistically, FGF12 induces MEF2a phosphorylation via p38MAPK signaling, modulating MEF2a target gene expression involved in cell proliferation and differentiation. In vivo, smooth muscle-specific FGF12 transgenic mice were protected from chronic hypoxia-induced PAH with increased MEF2a phosphorylation.","method":"siRNA knockdown and adenoviral overexpression in human PASMCs, BMP treatment, p38MAPK pathway analysis, transgenic mouse PAH model with MEF2a phosphorylation assay","journal":"Hypertension (Dallas, Tex. : 1979)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss/gain of function in vitro plus transgenic mouse in vivo, single lab, two orthogonal approaches","pmids":["33100045"],"is_preprint":false},{"year":2022,"finding":"FGF12 is localized to the nucleolus where it interacts with NOLC1 and TCOF1 (ribosome biogenesis proteins). NOLC1 and TCOF1 cannot interact with each other in the absence of FGF12, indicating FGF12 is required for assembly of this complex. The FGF12–NOLC1/TCOF1 interaction is phosphorylation-dependent and requires the C-terminal region of FGF12. Interactions with NOLC1 are unique to FGF12 among FHF proteins.","method":"Co-immunoprecipitation, proximity ligation assay, subcellular fractionation/immunofluorescence localization, deletion/phosphorylation mutant analysis","journal":"Cell communication and signaling : CCS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain mapping and localization, single lab, multiple orthogonal methods","pmids":["36411431"],"is_preprint":false},{"year":2021,"finding":"The FHF1/FGF12 p.Arg52His mutation in mice (introduced by CRISPR) causes epileptic encephalopathy with full penetrance. In FHF-deficient cardiomyocytes expressing FHF1BR52H, a 15-mV depolarizing shift in voltage of steady-state sodium channel inactivation and slowed inactivation rate were observed, confirming gain-of-function on cardiac Nav channels. Epileptic SUDEP was associated with bradycardia suggesting a parasympathetic surge.","method":"CRISPR knock-in mouse model, cortical EEG/video monitoring, ECG, voltage-clamp recordings in FHF-deficient cardiomyocytes infected with adenoviruses expressing WT or mutant FHF1B","journal":"Epilepsia","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vivo CRISPR model with EEG/ECG phenotype plus in vitro voltage-clamp in native cardiomyocytes, multiple orthogonal methods replicate earlier electrophysiology findings","pmids":["33982289"],"is_preprint":false},{"year":2022,"finding":"FGF12 variants differentially regulate NaV1.2 and NaV1.6 sodium channels, producing complex kinetic changes including both gain- and loss-of-function effects on fast and slow inactivation.","method":"Co-expression of wildtype and mutant FGF12 with NaV1.2 or NaV1.6 (plus SCN1B/SCN2B subunits) in ND7/23 neuronal-like cells, whole-cell patch-clamp electrophysiology","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro electrophysiology with multiple channel variants, single lab study","pmids":["36029553"],"is_preprint":false},{"year":2023,"finding":"FGF12 in hepatic macrophages promotes liver fibrosis by activating macrophage proinflammatory polarization (increasing Ly6C-high macrophages and proinflammatory cytokines/chemokines). FGF12 induces hepatic stellate cell (HSC) activation mainly through the MCP-1/CCR2 axis. Regulation of macrophage activation by FGF12 is mediated through the JAK-STAT signaling pathway.","method":"Myeloid-specific FGF12 knockout mice (BDL- and CCl4-induced fibrosis models), loss-of-function and gain-of-function in macrophages, flow cytometry, cytokine/chemokine analysis, pathway inhibitor studies","journal":"Hepatology (Baltimore, Md.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — myeloid-specific KO in two independent fibrosis models plus in vitro mechanistic follow-up, single lab","pmids":["35753047"],"is_preprint":false},{"year":2024,"finding":"The long 'a' isoform of FGF12 is secreted via an unconventional pathway involving the A1 subunit of Na+/K+ ATPase (ATP1A1), Tec kinase, and lipids (phosphatidylinositol and phosphatidylserine). The short 'b' isoform binds ATP1A1 and phosphatidylserine less efficiently and is not secreted. The N-terminal fragment and specific residues of FGF12a are crucial for secretion, and liquid-liquid phase separation may be important.","method":"Isoform-specific secretion assays, co-immunoprecipitation with ATP1A1, lipid-binding assays, siRNA knockdown of ATP1A1/Tec kinase, domain deletion/mutation analysis","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple binding and functional secretion assays with domain mapping, single lab","pmids":["39158730"],"is_preprint":false},{"year":2024,"finding":"Galectin-1 directly interacts with FGF12 in the cytosol and nucleus. Cytosolic galectin-1 binding to FGF12 blocks FGF12 secretion. Intracellular galectin-1 also affects assembly of FGF12-containing nucleolar ribosome biogenesis complexes (NOLC1/TCOF1).","method":"Co-immunoprecipitation, proximity ligation assay, secretion assay with galectin-1 overexpression/knockdown, subcellular localization by immunofluorescence","journal":"Cell communication and signaling : CCS","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP plus functional secretion readout plus complex assembly assay, single lab","pmids":["38468333"],"is_preprint":false},{"year":2024,"finding":"FGF12 selectively binds the RING domain of MDM2, partially inhibiting β-Trcp binding to MDM2 and thereby blocking β-Trcp-mediated K48 ubiquitination and degradation of MDM2. This stabilizes MDM2 and suppresses p53 signaling pathway activity, leading to excessive keratinocyte proliferation in psoriasis.","method":"Co-immunoprecipitation, ubiquitination assays, keratinocyte-specific FGF12 KO in imiquimod-induced psoriasis mouse model, RNA-seq, p53 rescue experiments","journal":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with domain identification, ubiquitination assay, cell-type-specific KO mouse model, single lab with multiple methods","pmids":["39234815"],"is_preprint":false},{"year":2024,"finding":"FGF12 overexpression in doxorubicin-injured cardiomyocytes activates FGFR1/AMPK/NRF2 signaling and inhibits ferroptosis (reduced iron deposition, decreased ACSL4/PTGS2, increased GPX4/FTH1). Silencing FGFR1 reversed the protective effects of FGF12, confirming the pathway dependence.","method":"FGF12 overexpression in HL-1 cells and in vivo DOX-injured mouse model, FGFR1 siRNA knockdown, ferroptosis markers (Prussian blue, western blot), oxidative stress assays","journal":"Drug development research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vitro and in vivo with pathway rescue by FGFR1 silencing, single lab","pmids":["38349269"],"is_preprint":false},{"year":2026,"finding":"FGF12 expression in aortic SMCs is induced by TGF-β/SMAD signaling and by cyclic mechanical stretch. FGF12 upregulates AngII and AT1R expression, activating the AngII/AT1R pathway, which promotes aberrant mechanosignaling (increased RhoA-GTP, stress fiber formation, focal adhesion assembly, FAK phosphorylation) and increased aortic SMC stiffness. In vivo, Fgf12 haploinsufficiency ameliorated TAA formation in MFS mice with reduced AT1R signaling.","method":"TGF-β/SMAD pathway stimulation, cyclic stretch experiments, RhoA activation assay, focal adhesion imaging, Fgf12+/- mouse TAA model, Fbn1C1039G/+;Fgf12+/- compound mutant mice","journal":"Experimental & molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro mechanistic pathway analysis plus two in vivo genetic mouse models, single lab","pmids":["41540272"],"is_preprint":false},{"year":2026,"finding":"FGF12 (outside the nucleus) binds calmodulin and inhibits its phosphorylation, suppressing downstream CaMKII, ERK1/2, CREB1, and MCU phosphorylation/expression and reducing mitochondrial Ca2+ and ROS. Nuclear-localized FGF12 binds the CREB1 promoter region (by CUT&TAG sequencing) and directly inhibits CREB1 expression. Both actions maintain cardiomyocyte function and mitochondrial homeostasis and reduce hypertrophy.","method":"AlphaFold3 structural prediction, Co-IP (FGF12-calmodulin binding), CUT&TAG sequencing (FGF12 promoter binding of CREB1), CRISPR-Cas9 in iPSC-derived cardiomyocytes, AAV9 delivery in HCM mouse models (MYH7R403Q/+, MYBPC3 mutant, TAC), mitochondrial Ca2+ and ROS measurements","journal":"Circulation. Genomic and precision medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus CUT&TAG plus multiple mouse models, single lab; AlphaFold3 is computational but supported by biochemical validation","pmids":["41979475"],"is_preprint":false},{"year":2026,"finding":"FHF1A (FGF12 long isoform) expression is reduced in failing human, rabbit, and murine hearts. A cell-penetrating peptide FixR derived from FHF1A selectively inhibits late Na+ current (INa,L) in heart failure cardiomyocytes without affecting peak Na+ current, L-type Ca2+ current, or major K+ currents, and reduces proarrhythmic action potential changes and delayed afterdepolarizations.","method":"Reverse-transcriptase quantitative PCR for FHF splice isoforms in human HF and animal models, whole-cell patch-clamp for INa,L and other currents in rabbit and murine HF cardiomyocytes, in vivo adenoviral delivery of FixR in transgenic CaMKIIδC mice with ECG/arrhythmia monitoring","journal":"Circulation research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology in multiple HF models (human, rabbit, mouse) plus in vivo arrhythmia recording, single lab with multiple orthogonal methods","pmids":["42186805"],"is_preprint":false},{"year":2025,"finding":"FGF12 interacts with the RNA-binding protein YB1 (identified by affinity purification-mass spectrometry and confirmed by co-IP), leading to stabilization of oncogenic long noncoding RNAs NEAT1 and MALAT1. RNA silencing of YB1 abrogated FGF12-mediated upregulation of these transcripts. This FGF12-YB1-lncRNA axis promotes cancer cell survival against chemotherapy.","method":"Affinity purification-mass spectrometry, Co-IP, RNA sequencing, YB1 siRNA knockdown, cell viability assays with etoposide/camptothecin","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — AP-MS plus Co-IP for binding, functional rescue with siRNA knockdown, single lab","pmids":["41294881"],"is_preprint":false},{"year":2008,"finding":"FHF1/FGF12 is expressed in a specific subpopulation of TrkA+/CGRP-positive nociceptive neurons in adult mouse DRG. FHF1 does not colocalize with Nav1.9 in cRet+/IB4+ neurons, providing negative evidence against a modulatory role on Nav1.9 in that subclass.","method":"Immunofluorescence co-labeling of FHF1 with neurotrophin receptors (TrkA, c-Ret), CGRP, NF-200, peripherin, and Nav1.9 in mouse DRG sections; developmental and post-axotomy expression analysis","journal":"The Journal of comparative neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct immunolocalization with multiple markers establishing subpopulation specificity and negative colocalization, single lab","pmids":["18220257"],"is_preprint":false}],"current_model":"FGF12 (FHF1) is an intracellular FGF homologous factor that functions primarily by binding the cytoplasmic C-terminal tails of voltage-gated sodium channels (Nav1.2, Nav1.5, Nav1.6) to modulate fast inactivation gating and channel density; gain-of-function mutations shift inactivation in a depolarizing direction to increase excitability (causing epileptic encephalopathy and arrhythmia), while loss-of-function reduces Na+ current. Beyond ion channel regulation, FGF12 localizes to the nucleolus where it scaffolds a NOLC1/TCOF1 ribosome biogenesis complex (requiring its C-terminal domain and phosphorylation), binds calmodulin to suppress the CaMKII/ERK/CREB1/MCU axis in cardiomyocytes, stabilizes MDM2 by blocking β-Trcp-mediated ubiquitination to suppress p53 in keratinocytes, interacts with YB1 to stabilize oncogenic lncRNAs, activates macrophage proinflammatory JAK-STAT signaling promoting liver fibrosis via the MCP-1/CCR2 axis, and is unconventionally secreted (long 'a' isoform only) through a pathway requiring ATP1A1, Tec kinase, and phospholipids."},"narrative":{"mechanistic_narrative":"FGF12 (FHF1) is an intracellular FGF homologous factor whose canonical role is regulation of voltage-gated sodium channel gating through direct binding to the cytoplasmic C-terminal tails of cardiac and neuronal Nav channels, thereby tuning membrane excitability [PMID:24096171, PMID:27164707]. In cardiomyocytes FGF12-B binds the NaV1.5 C-terminus to set Na+ current density and availability, and a Brugada-associated Q7R variant weakens this binding and reduces action potential amplitude [PMID:24096171]. In neurons, gain-of-function mutations such as p.Arg52His shift Nav1.6 fast inactivation in a depolarizing direction by weakening the FHF1–channel tail interaction, increasing excitability [PMID:27164707]; this variant causes fully penetrant epileptic encephalopathy in a CRISPR knock-in mouse and produces a depolarizing shift and slowed inactivation of cardiac Nav channels, linking seizures to arrhythmia/SUDEP [PMID:33982289]. FGF12 variants exert channel- and isoform-specific effects, producing mixed gain- and loss-of-function changes on NaV1.2 versus NaV1.6 fast and slow inactivation [PMID:36029553], and an FHF1A-derived cell-penetrating peptide selectively suppresses pathological late Na+ current in heart failure [PMID:42186805]. Beyond channel regulation, FGF12 acts as a multifunctional intracellular scaffold: it localizes to the nucleolus where its phosphorylated C-terminal region is required to bridge NOLC1 and TCOF1 into a ribosome-biogenesis complex [PMID:36411431], binds calmodulin to suppress a CaMKII/ERK/CREB1/MCU axis and directly represses CREB1 transcription to limit cardiomyocyte hypertrophy [PMID:41979475], stabilizes MDM2 by blocking β-Trcp-mediated ubiquitination to suppress p53 in keratinocytes [PMID:39234815], and engages YB1 to stabilize the oncogenic lncRNAs NEAT1 and MALAT1 [PMID:41294881]. FGF12 also signals through FGFRs—binding all four receptors and activating FGFR1/AMPK/NRF2 to inhibit cardiomyocyte ferroptosis [PMID:32357892, PMID:38349269]—and the long 'a' isoform is unconventionally secreted via an ATP1A1-, Tec kinase-, and phospholipid-dependent pathway that is blocked by cytosolic galectin-1 [PMID:39158730, PMID:38468333]. At the organ level, FGF12 promotes liver fibrosis through macrophage JAK-STAT and MCP-1/CCR2 signaling [PMID:35753047] and drives aortic aneurysm pathology by amplifying AngII/AT1R mechanosignaling in smooth muscle [PMID:41540272].","teleology":[{"year":2008,"claim":"Established that FGF12 acts intracellularly to control cell survival, addressing whether FHFs have functions beyond channel binding by placing FGF12 in the MEK/ERK anti-apoptotic axis.","evidence":"Overexpression/knockdown in HMC-1 mast cells with MEK/ERK inhibition and apoptosis assays; immunolocalization in TrkA+/CGRP+ DRG nociceptors","pmids":["18525161","18220257"],"confidence":"Medium","gaps":["Mechanism linking FGF12 to MEK/ERK not defined","Functional role of FGF12 in the specific DRG subpopulation not tested"]},{"year":2011,"claim":"Defined how exogenous FGF12 reaches the cytoplasm, identifying CPP-M and a subfamily-unique CPP-C domain that mediate cell penetration and an anti-apoptotic, radioprotective function.","evidence":"Recombinant protein internalization in IEC6 cells, CPP-C mutagenesis (E142L), chimeric FGF1/CPP-C constructs, and in vivo radiation apoptosis in mice","pmids":["21518765"],"confidence":"High","gaps":["Endogenous source of extracellular FGF12 not established here","Intracellular target mediating anti-apoptotic effect not identified"]},{"year":2013,"claim":"Connected FGF12 to cardiac sodium channel function and human disease by showing FGF12-B binds the NaV1.5 C-terminus and a Brugada variant impairs this to reduce Na+ current.","evidence":"Co-IP/pulldown of NaV1.5 C-terminus, FHF-swap voltage-clamp and action potential recordings in adult rat cardiomyocytes","pmids":["24096171"],"confidence":"High","gaps":["Structural basis of the FGF12-B/NaV1.5 interface not resolved","Effect on other cardiac channels limited to negative Ca2+ channel result"]},{"year":2016,"claim":"Showed FGF12 gain-of-function causes epilepsy, demonstrating that a p.Arg52His variant weakens channel-tail binding to shift Nav1.6 inactivation and increase excitability in vivo.","evidence":"Whole-cell patch-clamp in Neuro2A cells plus transgenic mutant FHF1B overexpression in zebrafish larvae","pmids":["27164707"],"confidence":"High","gaps":["Did not yet establish mammalian in vivo disease model","Quantitative binding affinity change not measured"]},{"year":2020,"claim":"Extended FGF12 function to extracellular FGFR signaling and to BMP/p38-MEF2a control of vascular smooth muscle quiescence, distinguishing it from mitogenic canonical FGFs.","evidence":"Direct FGFR1–4 binding and phosphorylation assays with apoptosis readouts; PASMC knockdown/overexpression with BMP treatment and a smooth-muscle FGF12 transgenic PAH mouse","pmids":["32357892","33100045"],"confidence":"Medium","gaps":["Physiological relevance of FGFR binding given intracellular localization unclear","How FGF12 couples to p38MAPK not defined"]},{"year":2021,"claim":"Provided definitive mammalian causation, showing the R52H knock-in produces fully penetrant epileptic encephalopathy with concordant gain-of-function on cardiac Nav channels linking seizures to arrhythmia.","evidence":"CRISPR knock-in mouse with EEG/ECG monitoring and voltage-clamp in FHF-deficient cardiomyocytes expressing WT or mutant FHF1B","pmids":["33982289"],"confidence":"High","gaps":["Cell-type contributions to SUDEP not dissected","Therapeutic reversibility not tested"]},{"year":2022,"claim":"Revealed a non-channel nucleolar role by showing FGF12 is required to assemble a NOLC1/TCOF1 ribosome-biogenesis complex, and refined channel pharmacology with variant- and isoform-specific gating effects.","evidence":"Co-IP, proximity ligation, fractionation and deletion/phosphorylation mutants for NOLC1/TCOF1; co-expression patch-clamp of NaV1.2 and NaV1.6 variants in ND7/23 cells","pmids":["36411431","36029553"],"confidence":"Medium","gaps":["Functional consequence of FGF12 on rRNA processing not measured","Kinase responsible for the required FGF12 phosphorylation unknown"]},{"year":2023,"claim":"Implicated FGF12 in organ fibrosis, showing macrophage FGF12 drives proinflammatory polarization and hepatic stellate cell activation through JAK-STAT and the MCP-1/CCR2 axis.","evidence":"Myeloid-specific FGF12 knockout in BDL and CCl4 fibrosis models with macrophage loss/gain-of-function and pathway inhibitor studies","pmids":["35753047"],"confidence":"Medium","gaps":["Direct molecular link between FGF12 and JAK-STAT activation not defined","Whether nuclear or channel functions are involved unknown"]},{"year":2024,"claim":"Mapped multiple distinct intracellular mechanisms and the secretion route: MDM2 stabilization/p53 suppression, FGFR1/AMPK/NRF2 anti-ferroptosis protection, isoform-selective unconventional secretion, and galectin-1 control of secretion and nucleolar complex assembly.","evidence":"Co-IP/ubiquitination assays and keratinocyte-specific KO psoriasis model (MDM2); FGFR1-silencing rescue in DOX cardiomyocytes (ferroptosis); isoform secretion assays with ATP1A1/Tec/lipid mapping; galectin-1 Co-IP and secretion/assembly assays","pmids":["39234815","38349269","39158730","38468333"],"confidence":"Medium","gaps":["How a single protein partitions among these mechanisms in a given cell unclear","Role of liquid-liquid phase separation in secretion not demonstrated functionally"]},{"year":2026,"claim":"Consolidated cardiac and vascular roles, showing calmodulin/CREB1 dual regulation limiting hypertrophy, AngII/AT1R mechanosignaling driving aortic aneurysm, and a FHF1A-derived peptide that selectively blocks pathological late Na+ current.","evidence":"Co-IP, CUT&TAG, iPSC-cardiomyocyte CRISPR and AAV9 HCM mouse models (calmodulin/CREB1); Fgf12+/- and Fbn1;Fgf12 compound mice with RhoA/FAK assays (aneurysm); RT-qPCR and patch-clamp across human/rabbit/mouse HF with in vivo FixR peptide delivery","pmids":["41979475","41540272","42186805"],"confidence":"Medium","gaps":["Reconciliation of FGF12 loss being protective in some tissues but pathogenic in others not resolved","Direct structural validation of calmodulin binding beyond computational prediction lacking"]},{"year":null,"claim":"It remains unknown how FGF12's many context-specific activities—channel gating, nucleolar scaffolding, transcriptional repression, ubiquitin pathway control, and secretion—are coordinated and partitioned within a single cell type.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model integrating cytoplasmic, nucleolar, nuclear, and secreted pools","Isoform-specific localization and function not systematically compared across tissues"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,7,8]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6,11]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[15]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[10]}],"localization":[{"term_id":"GO:0005730","term_label":"nucleolus","supporting_discovery_ids":[6,11]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[11,15]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[15]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,7,8]},{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,16]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[6,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,13,15]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[2,3,13]}],"complexes":["NOLC1/TCOF1 ribosome biogenesis complex"],"partners":["SCN5A","SCN8A","SCN2A","NOLC1","TCOF1","CALM1","MDM2","YBX1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P61328","full_name":"Fibroblast growth factor 12","aliases":["Fibroblast growth factor homologous factor 1","FHF-1","Myocyte-activating factor"],"length_aa":243,"mass_kda":27.4,"function":"Involved in nervous system development and function. Involved in the positive regulation of voltage-gated sodium channel activity. 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Transgenic overexpression of mutant FHF1B in zebrafish larvae enhanced epileptiform discharges.\",\n      \"method\": \"Whole-cell patch-clamp electrophysiology in transfected Neuro2A cells, in vivo zebrafish epilepsy model with transgenic overexpression\",\n      \"journal\": \"Neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro electrophysiology plus in vivo zebrafish model, single lab but two orthogonal methods with clear mechanistic readout\",\n      \"pmids\": [\"27164707\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"FGF12 is internalized into intestinal epithelial cell cytoplasm through two cell-penetrating peptide (CPP) domains: CPP-M (internal, common to FGF family) and CPP-C (~10 aa, C-terminal residues 140–149, unique to FGF12 subfamily). Mutation E142L in CPP-C drastically reduces internalization. Internalized exogenous FGF12 inhibits radiation-induced apoptosis in vivo (BALB/c mice), and deletion of CPP-C reduces this anti-apoptotic effect.\",\n      \"method\": \"Recombinant protein internalization assay in IEC6 cells, site-directed mutagenesis of CPP-C domain, chimeric FGF1/CPP-C protein internalization, in vivo intraperitoneal injection in BALB/c mice with apoptosis quantification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mutagenesis of functional domain combined with in vitro and in vivo functional readout in single lab, multiple orthogonal methods\",\n      \"pmids\": [\"21518765\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Intracellular FGF12 suppresses radiation-induced apoptosis in mast cells (HMC-1) via the MEK/ERK pathway; overexpression of FGF12 blocked the augmentation of apoptosis caused by MEK/ERK inhibitor PD98059. This anti-apoptotic effect was independent of the MAPK scaffold protein IB2 (which binds FGF12 but did not interfere with the anti-apoptotic effect).\",\n      \"method\": \"Overexpression and siRNA knockdown of FGF12 in HMC-1 cells, pharmacological inhibition of MEK/ERK with PD98059, apoptosis assay\",\n      \"journal\": \"Journal of radiation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean KD/OE with defined cellular phenotype and pathway placement via pharmacological inhibitor, single lab single study\",\n      \"pmids\": [\"18525161\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FGF12 directly interacts with all four major FGFRs (FGFR1–4), causing efficient FGFR activation and initiation of receptor-dependent signaling cascades. Extracellular FHF1/FGF12 protects cells from apoptosis but is unable to stimulate cell division, distinguishing it biologically from canonical FGFs.\",\n      \"method\": \"Direct binding assays (pulldown/Co-IP), FGFR phosphorylation assays, cell viability and apoptosis assays\",\n      \"journal\": \"Cell communication and signaling : CCS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct binding plus receptor activation plus functional apoptosis readout, single lab\",\n      \"pmids\": [\"32357892\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"FGF12 is required for BMP-mediated acquisition of quiescent/differentiated pulmonary arterial smooth muscle cell (PASMC) phenotype. Mechanistically, FGF12 induces MEF2a phosphorylation via p38MAPK signaling, modulating MEF2a target gene expression involved in cell proliferation and differentiation. In vivo, smooth muscle-specific FGF12 transgenic mice were protected from chronic hypoxia-induced PAH with increased MEF2a phosphorylation.\",\n      \"method\": \"siRNA knockdown and adenoviral overexpression in human PASMCs, BMP treatment, p38MAPK pathway analysis, transgenic mouse PAH model with MEF2a phosphorylation assay\",\n      \"journal\": \"Hypertension (Dallas, Tex. : 1979)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss/gain of function in vitro plus transgenic mouse in vivo, single lab, two orthogonal approaches\",\n      \"pmids\": [\"33100045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FGF12 is localized to the nucleolus where it interacts with NOLC1 and TCOF1 (ribosome biogenesis proteins). NOLC1 and TCOF1 cannot interact with each other in the absence of FGF12, indicating FGF12 is required for assembly of this complex. The FGF12–NOLC1/TCOF1 interaction is phosphorylation-dependent and requires the C-terminal region of FGF12. Interactions with NOLC1 are unique to FGF12 among FHF proteins.\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, subcellular fractionation/immunofluorescence localization, deletion/phosphorylation mutant analysis\",\n      \"journal\": \"Cell communication and signaling : CCS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain mapping and localization, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"36411431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The FHF1/FGF12 p.Arg52His mutation in mice (introduced by CRISPR) causes epileptic encephalopathy with full penetrance. In FHF-deficient cardiomyocytes expressing FHF1BR52H, a 15-mV depolarizing shift in voltage of steady-state sodium channel inactivation and slowed inactivation rate were observed, confirming gain-of-function on cardiac Nav channels. Epileptic SUDEP was associated with bradycardia suggesting a parasympathetic surge.\",\n      \"method\": \"CRISPR knock-in mouse model, cortical EEG/video monitoring, ECG, voltage-clamp recordings in FHF-deficient cardiomyocytes infected with adenoviruses expressing WT or mutant FHF1B\",\n      \"journal\": \"Epilepsia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vivo CRISPR model with EEG/ECG phenotype plus in vitro voltage-clamp in native cardiomyocytes, multiple orthogonal methods replicate earlier electrophysiology findings\",\n      \"pmids\": [\"33982289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FGF12 variants differentially regulate NaV1.2 and NaV1.6 sodium channels, producing complex kinetic changes including both gain- and loss-of-function effects on fast and slow inactivation.\",\n      \"method\": \"Co-expression of wildtype and mutant FGF12 with NaV1.2 or NaV1.6 (plus SCN1B/SCN2B subunits) in ND7/23 neuronal-like cells, whole-cell patch-clamp electrophysiology\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro electrophysiology with multiple channel variants, single lab study\",\n      \"pmids\": [\"36029553\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"FGF12 in hepatic macrophages promotes liver fibrosis by activating macrophage proinflammatory polarization (increasing Ly6C-high macrophages and proinflammatory cytokines/chemokines). FGF12 induces hepatic stellate cell (HSC) activation mainly through the MCP-1/CCR2 axis. Regulation of macrophage activation by FGF12 is mediated through the JAK-STAT signaling pathway.\",\n      \"method\": \"Myeloid-specific FGF12 knockout mice (BDL- and CCl4-induced fibrosis models), loss-of-function and gain-of-function in macrophages, flow cytometry, cytokine/chemokine analysis, pathway inhibitor studies\",\n      \"journal\": \"Hepatology (Baltimore, Md.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — myeloid-specific KO in two independent fibrosis models plus in vitro mechanistic follow-up, single lab\",\n      \"pmids\": [\"35753047\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The long 'a' isoform of FGF12 is secreted via an unconventional pathway involving the A1 subunit of Na+/K+ ATPase (ATP1A1), Tec kinase, and lipids (phosphatidylinositol and phosphatidylserine). The short 'b' isoform binds ATP1A1 and phosphatidylserine less efficiently and is not secreted. The N-terminal fragment and specific residues of FGF12a are crucial for secretion, and liquid-liquid phase separation may be important.\",\n      \"method\": \"Isoform-specific secretion assays, co-immunoprecipitation with ATP1A1, lipid-binding assays, siRNA knockdown of ATP1A1/Tec kinase, domain deletion/mutation analysis\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple binding and functional secretion assays with domain mapping, single lab\",\n      \"pmids\": [\"39158730\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Galectin-1 directly interacts with FGF12 in the cytosol and nucleus. Cytosolic galectin-1 binding to FGF12 blocks FGF12 secretion. Intracellular galectin-1 also affects assembly of FGF12-containing nucleolar ribosome biogenesis complexes (NOLC1/TCOF1).\",\n      \"method\": \"Co-immunoprecipitation, proximity ligation assay, secretion assay with galectin-1 overexpression/knockdown, subcellular localization by immunofluorescence\",\n      \"journal\": \"Cell communication and signaling : CCS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP plus functional secretion readout plus complex assembly assay, single lab\",\n      \"pmids\": [\"38468333\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"FGF12 selectively binds the RING domain of MDM2, partially inhibiting β-Trcp binding to MDM2 and thereby blocking β-Trcp-mediated K48 ubiquitination and degradation of MDM2. This stabilizes MDM2 and suppresses p53 signaling pathway activity, leading to excessive keratinocyte proliferation in psoriasis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, keratinocyte-specific FGF12 KO in imiquimod-induced psoriasis mouse model, RNA-seq, p53 rescue experiments\",\n      \"journal\": \"Advanced science (Weinheim, Baden-Wurttemberg, Germany)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with domain identification, ubiquitination assay, cell-type-specific KO mouse model, single lab with multiple methods\",\n      \"pmids\": [\"39234815\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"FGF12 overexpression in doxorubicin-injured cardiomyocytes activates FGFR1/AMPK/NRF2 signaling and inhibits ferroptosis (reduced iron deposition, decreased ACSL4/PTGS2, increased GPX4/FTH1). Silencing FGFR1 reversed the protective effects of FGF12, confirming the pathway dependence.\",\n      \"method\": \"FGF12 overexpression in HL-1 cells and in vivo DOX-injured mouse model, FGFR1 siRNA knockdown, ferroptosis markers (Prussian blue, western blot), oxidative stress assays\",\n      \"journal\": \"Drug development research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vitro and in vivo with pathway rescue by FGFR1 silencing, single lab\",\n      \"pmids\": [\"38349269\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FGF12 expression in aortic SMCs is induced by TGF-β/SMAD signaling and by cyclic mechanical stretch. FGF12 upregulates AngII and AT1R expression, activating the AngII/AT1R pathway, which promotes aberrant mechanosignaling (increased RhoA-GTP, stress fiber formation, focal adhesion assembly, FAK phosphorylation) and increased aortic SMC stiffness. In vivo, Fgf12 haploinsufficiency ameliorated TAA formation in MFS mice with reduced AT1R signaling.\",\n      \"method\": \"TGF-β/SMAD pathway stimulation, cyclic stretch experiments, RhoA activation assay, focal adhesion imaging, Fgf12+/- mouse TAA model, Fbn1C1039G/+;Fgf12+/- compound mutant mice\",\n      \"journal\": \"Experimental & molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro mechanistic pathway analysis plus two in vivo genetic mouse models, single lab\",\n      \"pmids\": [\"41540272\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FGF12 (outside the nucleus) binds calmodulin and inhibits its phosphorylation, suppressing downstream CaMKII, ERK1/2, CREB1, and MCU phosphorylation/expression and reducing mitochondrial Ca2+ and ROS. Nuclear-localized FGF12 binds the CREB1 promoter region (by CUT&TAG sequencing) and directly inhibits CREB1 expression. Both actions maintain cardiomyocyte function and mitochondrial homeostasis and reduce hypertrophy.\",\n      \"method\": \"AlphaFold3 structural prediction, Co-IP (FGF12-calmodulin binding), CUT&TAG sequencing (FGF12 promoter binding of CREB1), CRISPR-Cas9 in iPSC-derived cardiomyocytes, AAV9 delivery in HCM mouse models (MYH7R403Q/+, MYBPC3 mutant, TAC), mitochondrial Ca2+ and ROS measurements\",\n      \"journal\": \"Circulation. Genomic and precision medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus CUT&TAG plus multiple mouse models, single lab; AlphaFold3 is computational but supported by biochemical validation\",\n      \"pmids\": [\"41979475\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"FHF1A (FGF12 long isoform) expression is reduced in failing human, rabbit, and murine hearts. A cell-penetrating peptide FixR derived from FHF1A selectively inhibits late Na+ current (INa,L) in heart failure cardiomyocytes without affecting peak Na+ current, L-type Ca2+ current, or major K+ currents, and reduces proarrhythmic action potential changes and delayed afterdepolarizations.\",\n      \"method\": \"Reverse-transcriptase quantitative PCR for FHF splice isoforms in human HF and animal models, whole-cell patch-clamp for INa,L and other currents in rabbit and murine HF cardiomyocytes, in vivo adenoviral delivery of FixR in transgenic CaMKIIδC mice with ECG/arrhythmia monitoring\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology in multiple HF models (human, rabbit, mouse) plus in vivo arrhythmia recording, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"42186805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"FGF12 interacts with the RNA-binding protein YB1 (identified by affinity purification-mass spectrometry and confirmed by co-IP), leading to stabilization of oncogenic long noncoding RNAs NEAT1 and MALAT1. RNA silencing of YB1 abrogated FGF12-mediated upregulation of these transcripts. This FGF12-YB1-lncRNA axis promotes cancer cell survival against chemotherapy.\",\n      \"method\": \"Affinity purification-mass spectrometry, Co-IP, RNA sequencing, YB1 siRNA knockdown, cell viability assays with etoposide/camptothecin\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — AP-MS plus Co-IP for binding, functional rescue with siRNA knockdown, single lab\",\n      \"pmids\": [\"41294881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"FHF1/FGF12 is expressed in a specific subpopulation of TrkA+/CGRP-positive nociceptive neurons in adult mouse DRG. FHF1 does not colocalize with Nav1.9 in cRet+/IB4+ neurons, providing negative evidence against a modulatory role on Nav1.9 in that subclass.\",\n      \"method\": \"Immunofluorescence co-labeling of FHF1 with neurotrophin receptors (TrkA, c-Ret), CGRP, NF-200, peripherin, and Nav1.9 in mouse DRG sections; developmental and post-axotomy expression analysis\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct immunolocalization with multiple markers establishing subpopulation specificity and negative colocalization, single lab\",\n      \"pmids\": [\"18220257\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"FGF12 (FHF1) is an intracellular FGF homologous factor that functions primarily by binding the cytoplasmic C-terminal tails of voltage-gated sodium channels (Nav1.2, Nav1.5, Nav1.6) to modulate fast inactivation gating and channel density; gain-of-function mutations shift inactivation in a depolarizing direction to increase excitability (causing epileptic encephalopathy and arrhythmia), while loss-of-function reduces Na+ current. Beyond ion channel regulation, FGF12 localizes to the nucleolus where it scaffolds a NOLC1/TCOF1 ribosome biogenesis complex (requiring its C-terminal domain and phosphorylation), binds calmodulin to suppress the CaMKII/ERK/CREB1/MCU axis in cardiomyocytes, stabilizes MDM2 by blocking β-Trcp-mediated ubiquitination to suppress p53 in keratinocytes, interacts with YB1 to stabilize oncogenic lncRNAs, activates macrophage proinflammatory JAK-STAT signaling promoting liver fibrosis via the MCP-1/CCR2 axis, and is unconventionally secreted (long 'a' isoform only) through a pathway requiring ATP1A1, Tec kinase, and phospholipids.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"FGF12 (FHF1) is an intracellular FGF homologous factor whose canonical role is regulation of voltage-gated sodium channel gating through direct binding to the cytoplasmic C-terminal tails of cardiac and neuronal Nav channels, thereby tuning membrane excitability [#0, #1]. In cardiomyocytes FGF12-B binds the NaV1.5 C-terminus to set Na+ current density and availability, and a Brugada-associated Q7R variant weakens this binding and reduces action potential amplitude [#0]. In neurons, gain-of-function mutations such as p.Arg52His shift Nav1.6 fast inactivation in a depolarizing direction by weakening the FHF1–channel tail interaction, increasing excitability [#1]; this variant causes fully penetrant epileptic encephalopathy in a CRISPR knock-in mouse and produces a depolarizing shift and slowed inactivation of cardiac Nav channels, linking seizures to arrhythmia/SUDEP [#7]. FGF12 variants exert channel- and isoform-specific effects, producing mixed gain- and loss-of-function changes on NaV1.2 versus NaV1.6 fast and slow inactivation [#8], and an FHF1A-derived cell-penetrating peptide selectively suppresses pathological late Na+ current in heart failure [#16]. Beyond channel regulation, FGF12 acts as a multifunctional intracellular scaffold: it localizes to the nucleolus where its phosphorylated C-terminal region is required to bridge NOLC1 and TCOF1 into a ribosome-biogenesis complex [#6], binds calmodulin to suppress a CaMKII/ERK/CREB1/MCU axis and directly represses CREB1 transcription to limit cardiomyocyte hypertrophy [#15], stabilizes MDM2 by blocking β-Trcp-mediated ubiquitination to suppress p53 in keratinocytes [#12], and engages YB1 to stabilize the oncogenic lncRNAs NEAT1 and MALAT1 [#17]. FGF12 also signals through FGFRs—binding all four receptors and activating FGFR1/AMPK/NRF2 to inhibit cardiomyocyte ferroptosis [#4, #13]—and the long 'a' isoform is unconventionally secreted via an ATP1A1-, Tec kinase-, and phospholipid-dependent pathway that is blocked by cytosolic galectin-1 [#10, #11]. At the organ level, FGF12 promotes liver fibrosis through macrophage JAK-STAT and MCP-1/CCR2 signaling [#9] and drives aortic aneurysm pathology by amplifying AngII/AT1R mechanosignaling in smooth muscle [#14].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that FGF12 acts intracellularly to control cell survival, addressing whether FHFs have functions beyond channel binding by placing FGF12 in the MEK/ERK anti-apoptotic axis.\",\n      \"evidence\": \"Overexpression/knockdown in HMC-1 mast cells with MEK/ERK inhibition and apoptosis assays; immunolocalization in TrkA+/CGRP+ DRG nociceptors\",\n      \"pmids\": [\"18525161\", \"18220257\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking FGF12 to MEK/ERK not defined\", \"Functional role of FGF12 in the specific DRG subpopulation not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined how exogenous FGF12 reaches the cytoplasm, identifying CPP-M and a subfamily-unique CPP-C domain that mediate cell penetration and an anti-apoptotic, radioprotective function.\",\n      \"evidence\": \"Recombinant protein internalization in IEC6 cells, CPP-C mutagenesis (E142L), chimeric FGF1/CPP-C constructs, and in vivo radiation apoptosis in mice\",\n      \"pmids\": [\"21518765\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous source of extracellular FGF12 not established here\", \"Intracellular target mediating anti-apoptotic effect not identified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Connected FGF12 to cardiac sodium channel function and human disease by showing FGF12-B binds the NaV1.5 C-terminus and a Brugada variant impairs this to reduce Na+ current.\",\n      \"evidence\": \"Co-IP/pulldown of NaV1.5 C-terminus, FHF-swap voltage-clamp and action potential recordings in adult rat cardiomyocytes\",\n      \"pmids\": [\"24096171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the FGF12-B/NaV1.5 interface not resolved\", \"Effect on other cardiac channels limited to negative Ca2+ channel result\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed FGF12 gain-of-function causes epilepsy, demonstrating that a p.Arg52His variant weakens channel-tail binding to shift Nav1.6 inactivation and increase excitability in vivo.\",\n      \"evidence\": \"Whole-cell patch-clamp in Neuro2A cells plus transgenic mutant FHF1B overexpression in zebrafish larvae\",\n      \"pmids\": [\"27164707\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not yet establish mammalian in vivo disease model\", \"Quantitative binding affinity change not measured\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Extended FGF12 function to extracellular FGFR signaling and to BMP/p38-MEF2a control of vascular smooth muscle quiescence, distinguishing it from mitogenic canonical FGFs.\",\n      \"evidence\": \"Direct FGFR1–4 binding and phosphorylation assays with apoptosis readouts; PASMC knockdown/overexpression with BMP treatment and a smooth-muscle FGF12 transgenic PAH mouse\",\n      \"pmids\": [\"32357892\", \"33100045\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological relevance of FGFR binding given intracellular localization unclear\", \"How FGF12 couples to p38MAPK not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Provided definitive mammalian causation, showing the R52H knock-in produces fully penetrant epileptic encephalopathy with concordant gain-of-function on cardiac Nav channels linking seizures to arrhythmia.\",\n      \"evidence\": \"CRISPR knock-in mouse with EEG/ECG monitoring and voltage-clamp in FHF-deficient cardiomyocytes expressing WT or mutant FHF1B\",\n      \"pmids\": [\"33982289\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type contributions to SUDEP not dissected\", \"Therapeutic reversibility not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Revealed a non-channel nucleolar role by showing FGF12 is required to assemble a NOLC1/TCOF1 ribosome-biogenesis complex, and refined channel pharmacology with variant- and isoform-specific gating effects.\",\n      \"evidence\": \"Co-IP, proximity ligation, fractionation and deletion/phosphorylation mutants for NOLC1/TCOF1; co-expression patch-clamp of NaV1.2 and NaV1.6 variants in ND7/23 cells\",\n      \"pmids\": [\"36411431\", \"36029553\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of FGF12 on rRNA processing not measured\", \"Kinase responsible for the required FGF12 phosphorylation unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Implicated FGF12 in organ fibrosis, showing macrophage FGF12 drives proinflammatory polarization and hepatic stellate cell activation through JAK-STAT and the MCP-1/CCR2 axis.\",\n      \"evidence\": \"Myeloid-specific FGF12 knockout in BDL and CCl4 fibrosis models with macrophage loss/gain-of-function and pathway inhibitor studies\",\n      \"pmids\": [\"35753047\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between FGF12 and JAK-STAT activation not defined\", \"Whether nuclear or channel functions are involved unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapped multiple distinct intracellular mechanisms and the secretion route: MDM2 stabilization/p53 suppression, FGFR1/AMPK/NRF2 anti-ferroptosis protection, isoform-selective unconventional secretion, and galectin-1 control of secretion and nucleolar complex assembly.\",\n      \"evidence\": \"Co-IP/ubiquitination assays and keratinocyte-specific KO psoriasis model (MDM2); FGFR1-silencing rescue in DOX cardiomyocytes (ferroptosis); isoform secretion assays with ATP1A1/Tec/lipid mapping; galectin-1 Co-IP and secretion/assembly assays\",\n      \"pmids\": [\"39234815\", \"38349269\", \"39158730\", \"38468333\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How a single protein partitions among these mechanisms in a given cell unclear\", \"Role of liquid-liquid phase separation in secretion not demonstrated functionally\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Consolidated cardiac and vascular roles, showing calmodulin/CREB1 dual regulation limiting hypertrophy, AngII/AT1R mechanosignaling driving aortic aneurysm, and a FHF1A-derived peptide that selectively blocks pathological late Na+ current.\",\n      \"evidence\": \"Co-IP, CUT&TAG, iPSC-cardiomyocyte CRISPR and AAV9 HCM mouse models (calmodulin/CREB1); Fgf12+/- and Fbn1;Fgf12 compound mice with RhoA/FAK assays (aneurysm); RT-qPCR and patch-clamp across human/rabbit/mouse HF with in vivo FixR peptide delivery\",\n      \"pmids\": [\"41979475\", \"41540272\", \"42186805\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation of FGF12 loss being protective in some tissues but pathogenic in others not resolved\", \"Direct structural validation of calmodulin binding beyond computational prediction lacking\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how FGF12's many context-specific activities—channel gating, nucleolar scaffolding, transcriptional repression, ubiquitin pathway control, and secretion—are coordinated and partitioned within a single cell type.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model integrating cytoplasmic, nucleolar, nuclear, and secreted pools\", \"Isoform-specific localization and function not systematically compared across tissues\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 7, 8]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [15]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [10]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005730\", \"supporting_discovery_ids\": [6, 11]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [11, 15]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [15]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 7, 8]},\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 16]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [6, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 13, 15]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [2, 3, 13]}\n    ],\n    \"complexes\": [\"NOLC1/TCOF1 ribosome biogenesis complex\"],\n    \"partners\": [\"SCN5A\", \"SCN8A\", \"SCN2A\", \"NOLC1\", \"TCOF1\", \"CALM1\", \"MDM2\", \"YBX1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":7,"faith_pct":85.71428571428571}}