{"gene":"SCN8A","run_date":"2026-06-10T07:46:29","timeline":{"discoveries":[{"year":1995,"finding":"Scn8a encodes a voltage-gated sodium channel alpha subunit (Nav1.6) expressed in brain and spinal cord but not skeletal muscle or heart; an intragenic deletion at the transgene insertion site results in loss of expression, causing motor endplate disease (med) phenotype including progressive paralysis, muscle atrophy, Purkinje cell degeneration, and juvenile lethality in mice.","method":"Positional cloning, transgene-induced deletion, expression analysis (tissue Northern blot)","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — positional cloning with functional validation of loss-of-expression allele, replicated across multiple subsequent studies","pmids":["7670495"],"is_preprint":false},{"year":2000,"finding":"Nav1.6 (NaCh6) protein localizes to nodes of Ranvier in peripheral nerve and spinal cord, axon initial segments, dendrites of pyramidal cells, and motor neuron axons; it is the first sodium channel isoform localized to both nodes of Ranvier and dendrites.","method":"Immunohistochemistry with isoform-specific antibodies in rat nervous system sections","journal":"The Journal of comparative neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct protein localization with isoform-specific antibodies, replicated by multiple subsequent studies","pmids":["10745220"],"is_preprint":false},{"year":2003,"finding":"Recombinant Nav1.6 channels exhibit approximately 5-fold faster recovery from inactivation (repriming) and faster development of closed-state inactivation compared to Nav1.7, providing a molecular basis for high-frequency firing in large myelinated DRG neurons.","method":"Whole-cell patch clamp of recombinant Nav1.6 and Nav1.7 expressed in mouse DRG neurons","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological characterization in native neuronal context with quantitative comparison, single lab but rigorous","pmids":["12843211"],"is_preprint":false},{"year":2003,"finding":"Calmodulin (CaM) binds to the C-terminal domain of Nav1.6 in a calcium-independent manner; disrupting this interaction reduced Nav1.6 current amplitude by 62%, and CaM also modulates Nav1.6 inactivation kinetics in a calcium-dependent manner.","method":"GST-fusion protein pulldown, co-expression with CaM in transfected cells, whole-cell patch clamp, C-terminal mutagenesis","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro binding assay combined with mutagenesis and functional electrophysiology; calcium-independent binding and calcium-dependent modulation distinguished","pmids":["12967988"],"is_preprint":false},{"year":2003,"finding":"In EAE (experimental autoimmune encephalomyelitis), Nav1.6 co-localizes with the Na+/Ca2+ exchanger (NCX) along demyelinated axons; 73.5% of injured (beta-APP positive) axons co-express Nav1.6 and NCX, suggesting that Nav1.6-mediated sodium influx drives reverse NCX operation and calcium-mediated axonal degeneration.","method":"Triple-label fluorescent immunohistochemistry in mouse EAE spinal cord","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — co-localization by immunohistochemistry without direct functional test of the proposed mechanism, but replicated in subsequent MS studies","pmids":["14662515"],"is_preprint":false},{"year":2004,"finding":"Nav1.6 channels exhibit use-dependent potentiation (increased current) during rapid repetitive depolarizations, in contrast to Nav1.2 which shows use-dependent decrease; this results from faster channel activation and resistance to slow inactivation in Nav1.6.","method":"Whole-cell patch clamp of Nav1.6 and Nav1.2 co-expressed with beta1 in Xenopus oocytes; fast inactivation-removed mutant channels used to dissect mechanism","journal":"Biophysical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mutagenesis to remove fast inactivation, mechanistic dissection of potentiation vs. slow inactivation","pmids":["15465873"],"is_preprint":false},{"year":2005,"finding":"p38 MAP kinase (p38alpha) phosphorylates Nav1.6 specifically at serine 553 within cytoplasmic loop L1 (joining domains 1 and 2); activation of p38 in neuronal cells significantly reduces Nav1.6 peak current amplitude without affecting gating; S553A substitution prevents this p38-mediated reduction.","method":"In vitro kinase assay with GST-fusion fragments of Nav1.6, site-directed mutagenesis (S553A), whole-cell patch clamp in p38-activated ND7/23 cells transfected with Nav1.6","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro kinase assay identifying specific phosphorylation site, confirmed by mutagenesis and functional electrophysiology","pmids":["16014723"],"is_preprint":false},{"year":2006,"finding":"Nav1.6 is required for repetitive high-frequency firing in retinal ganglion cells (RGCs); in Nav1.6-null (med) mice, maximal sustained and instantaneous firing rates are reduced by postnatal day 18. Compensatory upregulation of Nav1.2 and Nav1.1 at axon initial segments and nodes occurs in a cell-type-specific manner.","method":"Whole-cell patch clamp recordings from RGCs during postnatal development in med vs. wild-type mice; immunofluorescence for sodium channel isoforms at AIS and nodes","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO phenotype with direct electrophysiological readout, complemented by immunolocalization, replicated across multiple cell types","pmids":["16822974"],"is_preprint":false},{"year":2007,"finding":"Nav1.6 channels underlie resurgent sodium current in globus pallidus (GPe) neurons; Nav1.6-null GPe neurons show significantly reduced resurgent current, impaired pacemaking and fast spiking, and inability to follow high-frequency stimulation.","method":"Whole-cell patch clamp in acutely isolated GPe neurons from Nav1.6-null mice; computational modeling","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO neurons with direct electrophysiological phenotype, resurgent current attribution confirmed by null comparison and modeling","pmids":["18057213"],"is_preprint":false},{"year":2008,"finding":"Nav1.6 expression and persistent sodium current increase selectively in hippocampal CA3 neurons following kindling; heterozygous Nav1.6-deficient mice (Nav1.6+/-) resist initiation and development of kindling, identifying Nav1.6 as a participant in activity-dependent facilitation in hippocampal circuits.","method":"Immunocytochemistry, in situ hybridization, patch clamp recordings, kindling behavioral analysis in wild-type vs. Nav1.6+/- mice","journal":"Epilepsia","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (protein, mRNA, current, behavior), genetic reduction with defined functional phenotype","pmids":["18637833"],"is_preprint":false},{"year":2009,"finding":"FGF14 N-terminal splice variants (FGF14-1a and FGF14-1b) differentially regulate Nav1.6 currents: FGF14-1b (but not FGF14-1a) attenuates Nav1.6 current density; an FGF14 mutant lacking the N-terminus increases Nav1.6 current density; the N-terminus is required for axon initial segment targeting of FGF14.","method":"Co-expression in neurons with patch clamp, immunofluorescence localization in neurons, deletion mutagenesis","journal":"Molecular and cellular neurosciences","confidence":"High","confidence_rationale":"Tier 2 / Moderate — functional electrophysiology with deletion mutagenesis and localization data, single lab","pmids":["19465131"],"is_preprint":false},{"year":2009,"finding":"Mechanical membrane trauma (bleb-inducing aspiration or uniaxial stretch) causes Nav1.6 channels to exhibit irreversible hyperpolarizing shifts in steady-state inactivation and activation, expanding window current; stretch of Nav1.6-expressing HEK cells causes tetrodotoxin-sensitive cytoplasmic Na+ increase, demonstrating Nav1.6 acts as a mechanosensitive sodium leak channel.","method":"Patch clamp of recombinant Nav1.6 in oocyte patches (cell-attached aspiration) and HEK cells (substrate stretch); Na+-dye fluorimetry","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological measurement of channel response to defined mechanical stimuli, TTX-sensitive Na+ influx confirmed by dye imaging","pmids":["19657055"],"is_preprint":false},{"year":2010,"finding":"Nav1.6 at axon initial segments contributes to persistent (but not transient or resurgent) sodium current in cerebellar granule cells; loss of Nav1.6 at AIS leads to faster action potential repolarization, larger post-spike hyperpolarization, and increased interspike-interval variability, demonstrating a role in temporal precision of repetitive firing.","method":"Whole-cell patch clamp of acute cerebellar slices and acutely dissociated granule cells from granule cell-specific Scn8a conditional KO mice; immunofluorescence for Nav subunits","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with direct electrophysiological characterization distinguishing persistent from transient and resurgent currents","pmids":["20173079"],"is_preprint":false},{"year":2010,"finding":"Beta1 (Scn1b) subunit is required for normal Nav1.6 localization at the axon initial segment during postnatal development; in Scn1b-null cerebellar granule neurons, Nav1.6 at AIS is reduced and Nav1.1 substitutes; beta1-mediated neurite outgrowth requires Nav1.6-mediated sodium current, and Nav1.6 resurgent current is reduced in Scn1b-null neurons.","method":"Immunofluorescence of AIS in Scn1b-null cerebellar neurons, whole-cell patch clamp recording of resurgent current, shRNA knockdown of Nav1.6","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional interaction demonstrated by KO, immunolocalization, and electrophysiology with multiple orthogonal methods","pmids":["20133873"],"is_preprint":false},{"year":2011,"finding":"Rbfox proteins (Fox-1 and Fox-2) regulate alternative splicing of SCN8A by promoting inclusion of exon 18A over exon 18N; exon 18A selection is dependent on a Fox consensus binding site 28 bp downstream of exon 18A; exon 18A is required for production of functional full-length Nav1.6 protein.","method":"Scn8a minigene co-transfection with Fox-1 or Fox-2; mutagenesis of Fox binding site; RT-PCR of purified cell populations (neurons vs. glia)","journal":"Molecular and cellular neurosciences","confidence":"High","confidence_rationale":"Tier 1 / Moderate — minigene splicing assay with binding site mutagenesis, single lab with multiple orthogonal validations","pmids":["22044765"],"is_preprint":false},{"year":2012,"finding":"The N-terminal domain of Nav1.6 (residues 1-153) interacts with the light chain of microtubule-associated protein Map1b; residues 77-80 (VAVP) contribute to this interaction; Map1b co-immunoprecipitates with endogenous Nav1.6 from mouse brain; co-expression of Map1b with Nav1.6 increases current density ~50%; mutation of the Map1b binding site prevents sodium current generation, establishing Map1b as a trafficking partner for Nav1.6.","method":"Yeast two-hybrid screen, co-immunoprecipitation from mouse brain, alanine-scanning mutagenesis, whole-cell patch clamp in ND7/23 cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — yeast two-hybrid confirmed by co-IP from brain, mutagenesis identifies binding residues, functional electrophysiology validates consequence","pmids":["22474336"],"is_preprint":false},{"year":2013,"finding":"In vivo knockdown of Nav1.6 in rat lumbar DRG via siRNA completely blocked development of mechanical pain behaviors and abnormal spontaneous bursting activity following local DRG inflammation; cells capable of repetitive firing had higher Nav1.6 expression, and spontaneously active bursting cells in inflamed DRG expressed high Nav1.6 immunoreactivity.","method":"In vivo siRNA knockdown, behavioral pain testing (paw withdrawal threshold), single-unit electrophysiology, qPCR and immunohistochemistry","journal":"Pain","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo loss-of-function with defined behavioral and electrophysiological readouts, multiple methods in single study","pmids":["23622763"],"is_preprint":false},{"year":2014,"finding":"The de novo SCN8A mutation p.Asn1768Asp (N1768D) results in increased persistent sodium current and neuronal hyperactivity; knock-in mice carrying this mutation exhibit seizures, SUDEP, and EEG-confirmed ictal discharges; severity scales with mutant protein dose (heterozygous < hemizygous < homozygous).","method":"Knock-in mouse model, video/EEG analysis, behavioral testing, transfected cell electrophysiology","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — knock-in model with EEG confirmation, dose-response genetic analysis (het/hemi/homo), replicated by multiple subsequent studies","pmids":["25227913"],"is_preprint":false},{"year":2014,"finding":"The de novo SCN8A mutation p.Thr767Ile causes enhanced channel activation with a 10 mV depolarizing shift in voltage dependence, increased ramp current, and increased spontaneous firing with paroxysmal depolarizing shift-like complexes in hippocampal neurons, establishing a gain-of-function mechanism for epilepsy.","method":"Site-directed mutagenesis, whole-cell patch clamp in transfected neuronal cells and hippocampal pyramidal neurons","journal":"Neurobiology of disease","confidence":"High","confidence_rationale":"Tier 1 / Moderate — electrophysiology in both heterologous system and primary neurons, mutagenesis, single lab","pmids":["24874546"],"is_preprint":false},{"year":2015,"finding":"Amyloid precursor protein (APP) co-localizes and interacts with Nav1.6 in mouse cortical neurons; APP knockdown decreases Nav1.6 currents and cell surface expression; APP increases Nav1.6 surface expression through a Go protein-dependent, JNK-mediated pathway; phosphorylation of APP at Thr668 by JNK enhances APP-Nav1.6 interaction and Nav1.6 surface expression.","method":"Co-immunoprecipitation, siRNA knockdown, dominant-active/negative Go mutants, JNK inhibitors, T668E/T668A mutagenesis, whole-cell patch clamp, surface biotinylation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reciprocal co-IP plus mutagenesis plus functional electrophysiology plus pharmacological dissection in single study","pmids":["25767117"],"is_preprint":false},{"year":2015,"finding":"The PI3K/Akt pathway, Wee1 kinase, and protein kinase C (PKC) regulate the FGF14:Nav1.6 protein-protein interaction complex; inhibition of GSK3 (a convergence point of these pathways) impairs excitability of hippocampal neurons.","method":"Split-luciferase complementation assay in live cells screening 12 kinase inhibitor pathways; dose-response validation; hippocampal neuron electrophysiology","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — LCA assay with pharmacological inhibitors, validated by neuronal electrophysiology, but mechanism is indirect (through FGF14 interaction) and single lab","pmids":["25659151"],"is_preprint":false},{"year":2015,"finding":"Nav1.6 is required for spike initiation at stretch-sensitive colorectal afferent endings; selective Nav1.6 antagonists (mu-conotoxin GIIIa and PIIIa) significantly reduced afferent responses to colorectal stretch, while Nav1.7 or Nav1.8 antagonists did not; computational modeling confirmed Nav1.6 is necessary for tonic spiking at sensory endings.","method":"In vitro colon-nerve preparation with selective toxin pharmacology, immunohistochemistry/Western blot, computational modeling","journal":"Journal of neurophysiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — isoform-selective pharmacology with negative controls for other isoforms, supported by computational modeling","pmids":["25652923"],"is_preprint":false},{"year":2016,"finding":"Epilepsy-associated Nav1.6 mutations N1768D and L1331V dramatically increase resurgent sodium currents; cannabidiol preferentially inhibits resurgent and persistent sodium currents from wild-type and mutant Nav1.6 over peak transient currents; this inhibition reduces action potential firing in striatal neurons.","method":"Whole-cell patch clamp in HEK293T cells with Navβ4 peptide to induce resurgent current; Nav1.6 mutant channels; current clamp in striatal neurons","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct channel electrophysiology with disease mutations, pharmacological dissection of current subtypes, confirmed in native neurons","pmids":["27267376"],"is_preprint":false},{"year":2016,"finding":"The SCN8A gain-of-function mutation p.Met136Val increases peak current density (~1.5-fold) and resurgent current (~1.6-fold) without altering gating properties; it increases the fraction of high-firing neurons, lowers current threshold, and increases action potential frequency in trigeminal ganglion neurons.","method":"Whole-cell voltage clamp in transfected cells, current clamp in trigeminal ganglion neurons","journal":"Molecular medicine (Cambridge, Mass.)","confidence":"High","confidence_rationale":"Tier 1 / Moderate — electrophysiology in both heterologous and native neuron contexts, single lab","pmids":["27496104"],"is_preprint":false},{"year":2016,"finding":"CDYL (Chromodomain Y-like) epigenetic factor binds a regulatory element in the intron of SCN8A and recruits H3K27me3 activity to repress Nav1.6 transcription; CDYL knockdown in hippocampal neurons augments Nav1.6 currents and lowers seizure threshold; CDYL overexpression raises neuronal threshold and reduces epileptogenesis.","method":"Chromatin immunoprecipitation (ChIP), co-immunoprecipitation, siRNA knockdown, transgenic overexpression, patch clamp recordings, seizure susceptibility testing in mice","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP identifies direct binding to SCN8A intron, functional consequence confirmed by both loss- and gain-of-function in vivo, multiple orthogonal methods","pmids":["28842554"],"is_preprint":false},{"year":2016,"finding":"Nav1.6 somatic nanoclusters (~230 nm diameter) exist on the surface of hippocampal neuron soma that are stable for >30 minutes via an ankyrin-independent mechanism; non-clustered Nav1.6 channels show anomalous diffusion and can be transiently trapped in nanoclusters.","method":"Single-particle tracking, photoactivation localization microscopy (PALM), mean-square displacement analysis, Bayesian inference analysis","journal":"Biophysical journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct single-molecule imaging with multiple analytical methods, ankyrin independence established","pmids":["27653482"],"is_preprint":false},{"year":2017,"finding":"Loss of Scn8a in reticular thalamic (RT) neurons alters intrinsic RT cell excitability and causes failure in recurrent RT-RT synaptic inhibition, leading to enhanced thalamocortical network synchrony and absence epilepsy (spike-wave discharges); deletion of Scn8a in adult thalamus alone is sufficient to generate spike-wave discharges.","method":"Conditional KO (Cre-dependent deletion in RT cells), EEG recording, patch clamp in thalamic slices, adult-specific deletion","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell type-specific and adult-specific conditional KO with direct EEG and electrophysiological measurements of two distinct mechanisms","pmids":["28238546"],"is_preprint":false},{"year":2017,"finding":"Gain-of-function SCN8A mutation p.Asn1768Asp (N1768D) increases persistent sodium current density selectively in hippocampal CA1 pyramidal neurons (not bipolar neurons) and CA3 pyramidal and bipolar neurons; CA1 pyramidal neurons show early afterdepolarization-like action potential waveforms blocked by TTX, riluzole, and reverse Na/Ca exchange inhibitor SN-6, implicating elevated persistent INa and reverse NCX in hyperexcitability.","method":"Patch clamp of acutely dissociated neurons and brain slices from Scn8a N1768D knock-in mice; pharmacological dissection with TTX, riluzole, SN-6","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — knock-in model with cell-type-specific analysis, pharmacological mechanism dissection, multiple orthogonal approaches","pmids":["28193882"],"is_preprint":false},{"year":2019,"finding":"Restricting expression of the gain-of-function SCN8A mutation p.Arg1872Trp to excitatory neurons (via Emx1-Cre) recapitulates seizures and juvenile lethality; expression in inhibitory neurons (Gad2-Cre or Dlx5/6-Cre) does not induce seizures, establishing excitatory neurons as the critical cell type for SCN8A encephalopathy pathogenesis.","method":"Conditional knock-in mouse model with neuron-type-specific Cre drivers (Emx1-Cre, Gad2-Cre, Dlx5/6-Cre); EEG monitoring; survival analysis","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific conditional expression with multiple Cre drivers and EEG confirmation, clear positive (excitatory) and negative (inhibitory) results","pmids":["30601941"],"is_preprint":false},{"year":2019,"finding":"Multiple SCN8A epilepsy mutations (E1483K, R1872W) increase neuronal firing in primary neuronal cultures; loss-of-function mutations (R1620L) reduce neuronal firing; A1622D dramatically slows fast inactivation and induces depolarization block reducing neuronal firing despite epileptic presentation, confirming distinct genotype-phenotype correlations.","method":"Whole-cell patch clamp in neuroblastoma cells and primary cultured neurons; current clamp in neurons; computational modeling","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 1 / Strong — electrophysiology in two independent systems (cell line + neurons) for 7 mutations with computational validation, reveals mechanism of depolarization block","pmids":["30615093"],"is_preprint":false},{"year":2019,"finding":"TNF-α/STAT3 signaling upregulates Nav1.6 in DRG neurons: STAT3 binds the Scn8a promoter, interacts with p300, and promotes histone H4 hyperacetylation at the Scn8a promoter region, leading to increased Nav1.6 transcription following L5 ventral root transection; TNF-α inhibition reduces STAT3 recruitment and Nav1.6 upregulation.","method":"Chromatin immunoprecipitation (ChIP), co-immunoprecipitation (STAT3-p300), qPCR, Western blot, in vivo pharmacology","journal":"Journal of neuroinflammation","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP directly demonstrates STAT3 binding to Scn8a promoter, co-IP for STAT3-p300 interaction, pharmacological rescue, multiple methods","pmids":["30736806"],"is_preprint":false},{"year":2020,"finding":"Scn8a antisense oligonucleotide (ASO) treatment reducing Scn8a transcript by 25-50% delays seizure onset and lethality in the Scn8a-R1872W mouse model in a dose-dependent manner; a single Scn8a ASO treatment also extends survival of Dravet syndrome (Scn1a+/-) mice from 3 weeks to >5 months.","method":"Intracerebroventricular ASO injection in conditional Scn8a-R1872W knock-in mice and Scn1a+/- mice; EEG recording; survival analysis; open field and wheel running assays","journal":"Annals of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — dose-dependent in vivo rescue with EEG confirmation, tested in two independent mouse models","pmids":["31943325"],"is_preprint":false},{"year":2020,"finding":"CaMKII phosphorylates Nav1.6 at Ser-561 and Ser-641/Thr-642 within the first intracellular loop; CaMKII inhibition reduces Nav1.6 transient and persistent currents by ~72% and causes a 5.8 mV depolarizing shift in activation; S561A and S641A/T642A substitutions recapitulate these effects, demonstrating CaMKII modulates Nav1.6 channel activity.","method":"CaMKII-specific inhibitor CN21, whole-cell voltage clamp in Purkinje neurons and ND7/23/HEK293 cells, immobilized peptide arrays, LC-MS/MS phosphoproteomics, site-directed mutagenesis, computational modeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — mass spectrometry identifies phosphorylation sites, mutagenesis confirms functional roles, electrophysiology in native and heterologous systems","pmids":["32611770"],"is_preprint":false},{"year":2020,"finding":"Nav1.6 undergoes S-palmitoylation in mouse brain at three sites (Cys1169, Cys1170, Cys1978); enhancing palmitoylation increases Nav1.6 current while blocking it reduces current and shifts steady-state inactivation; Cys1978 is exclusive to Nav1.6 among all Nav isoforms and its palmitoylation specifically regulates current amplitude; loss of S-palmitoylation at specific sites alters neuronal excitability in DRG neurons.","method":"Acyl-biotin exchange assay in mouse brain and HEK cells, whole-cell voltage clamp with palmitic acid and 2-bromopalmitate, site-directed mutagenesis, current clamp in DRG neurons","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — biochemical detection of palmitoylation in vivo, site-specific mutagenesis, pharmacological modulation, functional confirmation in native neurons","pmids":["32161114"],"is_preprint":false},{"year":2020,"finding":"JAK2 phosphorylates FGF14 at Y158, a site that mediates both FGF14 homodimerization and FGF14:Nav1.6 complex formation; JAK2 inhibition increases FGF14 homodimerization while decreasing FGF14:Nav1.6 interaction; through Y158, JAK2 controls FGF14-dependent modulation of Nav1.6 channels; JAK2 inhibitor Fedratinib reduces hippocampal CA1 firing in a FGF14-dependent manner.","method":"High-throughput screening (split-luciferase), in vitro phosphorylation, mass spectrometry, FGF14Y158A mutagenesis, patch clamp electrophysiology in hippocampal neurons","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"High","confidence_rationale":"Tier 1 / Strong — MS identifies phosphorylation site, mutagenesis validates specificity, functional electrophysiology with genetic dependency confirmed","pmids":["32599005"],"is_preprint":false},{"year":2020,"finding":"Patient iPSC-derived neurons from SCN8A-related epilepsy exhibit variant-specific alterations: mutations p.R1872L and p.V1592L show elevated persistent current, while p.N1759S shows increased resurgent current; all three patient neuron lines have shorter axon initial segment lengths and prolonged action potential repolarization compared to controls.","method":"Patient iPSC-derived excitatory neurons, whole-cell patch clamp, immunofluorescence for AIS length (ankyrin-G staining), MEA network activity","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient-specific iPSC model with electrophysiology revealing variant-specific mechanisms, multiple orthogonal methods","pmids":["32968789"],"is_preprint":false},{"year":2021,"finding":"Selective expression of gain-of-function SCN8A mutation R1872W in somatostatin (SST) interneurons confers audiogenic seizure susceptibility; SST interneurons from mutant mice are hyperexcitable but hypersensitive to depolarization block; aberrantly large persistent sodium currents contribute directly to SST dysfunction; GqDREADD activation of WT SST interneurons also produces prolonged electrographic seizures.","method":"Cre-dependent conditional knock-in (SST-Cre), EEG, patch clamp electrophysiology, pharmacology, computational modeling, chemogenetics (GqDREADD)","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific conditional expression, electrophysiology identifying persistent current mechanism, pharmacological and chemogenetic validation","pmids":["34544834"],"is_preprint":false},{"year":2022,"finding":"Reducing Nav1.6 expression in hippocampus (via shRNA AAV) rescues cognitive impairments and attenuates synaptic deficits in APP/PS1 Alzheimer's model mice; Nav1.6 knockdown reduces Aβ levels by suppressing BACE1 transcription through a mechanism involving reduced intracellular calcium overload (via suppressed reverse NCX), increased inactive NFAT1, and thereby decreased BACE1 transcription.","method":"AAV-shRNA hippocampal injection, behavioral tests (Morris water maze), amyloid plaque quantification, ELISA, Western blot, calcium imaging","journal":"Aging cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo knockdown with multiple functional readouts, but proposed NFAT1-BACE1 pathway is partially inferred; single lab","pmids":["35353937"],"is_preprint":false},{"year":2023,"finding":"The MAPK-ERK-CREB signaling pathway upregulates Nav1.6 (Scn8a) transcription in DRG during oxaliplatin-induced neuropathic pain; activated p-CREB directly binds the Scn8a promoter region as demonstrated by ChIP; inhibition of CREB reduces Nav1.6 mRNA and protein and alleviates pain.","method":"Western blot, RT-qPCR, ChIP, immunofluorescence, in vivo kinase inhibitor pharmacology in rats","journal":"Toxicology letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP directly demonstrates CREB binding to Scn8a promoter, pharmacological intervention confirms pathway, single lab","pmids":["37453670"],"is_preprint":false},{"year":2024,"finding":"Selective expression of gain-of-function SCN8A variant R1872W in parvalbumin (PV) interneurons is sufficient to cause spontaneous seizures and seizure-induced death; PV interneurons from mutant mice show increased persistent sodium current, susceptibility to depolarization block, and reduced inhibitory synaptic transmission onto pyramidal cells.","method":"PV-Cre conditional knock-in, EEG, patch clamp electrophysiology (persistent current, evoked firing, IPSCs in pyramidal cells)","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific conditional knock-in with EEG, electrophysiology of intrinsic and synaptic properties, identifying both intrinsic and circuit mechanisms","pmids":["39435659"],"is_preprint":false},{"year":2024,"finding":"SCN8A alternative splicing isoforms (neonatally expressed NaV1.6N vs. adult NaV1.6A) show small but significant differences in voltage dependence; many disease-associated variants exhibit isoform-dependent functional effects; TTX-resistant versions of both isoforms show significant functional differences from WT channels, highlighting the importance of molecular context in variant characterization.","method":"Automated patch clamp in ND7/LoNav cells (engineered low-endogenous-Nav cell line), comparison of 15 variants in two splice isoforms with and without TTX-resistance mutations","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic functional comparison of splice isoforms and disease variants using improved cell model, high-throughput electrophysiology, single lab","pmids":["38771640"],"is_preprint":false},{"year":2011,"finding":"Beta-subunit regulation of Nav1.6 is weak compared to Nav1.8; the beta4-subunit induces a hyperpolarizing shift in Nav1.6 activation (-7.6 mV) but does not alter inactivation or current density; the intracellular C-terminal domain of the beta1-subunit is essential for strong regulation of Nav1.8 but not Nav1.6.","method":"Co-expression of Nav1.6 with beta1-beta4 subunits in Xenopus oocytes, whole-cell patch clamp, beta-subunit chimera analysis","journal":"Journal of neurophysiology","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — systematic co-expression electrophysiology with chimeras identifying functional domain, single lab, some negative results mechanistically informative","pmids":["21562192"],"is_preprint":false},{"year":2016,"finding":"FHF2 isoforms differentially regulate Nav1.6-mediated resurgent currents in DRG neurons: FHF2A enhances long-term inactivation and negatively regulates fast resurgent current; FHF2B lacks this long-term inactivation enhancement and positively regulates resurgent current; FHF2A and FHF2B expression are differentially regulated in a radicular pain model.","method":"Patch clamp electrophysiology in DRG neurons and cell lines; FHF2A/Navβ4 chimeric constructs; FHF2 isoform-specific siRNA knockdown","journal":"Pflugers Archiv : European journal of physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with chimeric constructs in native neurons, single lab, identifies differential gating mechanism","pmids":["27999940"],"is_preprint":false},{"year":2019,"finding":"Nav1.6 deletion from retinal ganglion cells (via AAV-Cre in Scn8a-floxed mice) during EAE reduces pro-inflammatory cytokines (IL-6, IFN-γ) and reactive gliosis marker (GFAP) expression, reduces macrophage infiltration in targeted optic nerves, and improves axonal health, demonstrating Nav1.6 promotes neuroinflammation and axonal degeneration following demyelination.","method":"AAV-Cre conditional deletion in floxed Scn8a mice during EAE, gene expression analysis, immunohistochemistry, contralateral eye controls","journal":"Journal of neuroinflammation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional cell-type-specific deletion with multiple outcome measures, single lab, intra-animal control","pmids":["31722722"],"is_preprint":false}],"current_model":"SCN8A encodes Nav1.6, a voltage-gated sodium channel alpha subunit highly expressed at axon initial segments and nodes of Ranvier in the CNS and PNS, where it is essential for repetitive high-frequency firing, resurgent and persistent sodium currents, and action potential generation; its activity is regulated by multiple post-translational mechanisms including phosphorylation by p38 MAPK (at S553), CaMKII (at S561, S641/T642), and JAK2 (via FGF14-Y158), S-palmitoylation (at C1169, C1170, C1978), and calcium-dependent and independent calmodulin binding at the C-terminus; trafficking to the cell surface requires interaction with Map1b (via N-terminal residues 77-80) and beta1 subunit, and alternative splicing of exon 18A is controlled by RBFOX proteins to produce functional protein; transcription of SCN8A is epigenetically repressed by CDYL-H3K27me3 and can be upregulated by TNF-α/STAT3-p300 histone acetylation or MAPK-ERK-CREB signaling; gain-of-function mutations increase persistent and/or resurgent currents causing neuronal hyperexcitability and epileptic encephalopathy, primarily through excitatory neurons but also via failure of SST and PV inhibitory interneurons (depolarization block and synaptic transmission deficits), while loss-of-function causes intellectual disability and movement disorders."},"narrative":{"mechanistic_narrative":"SCN8A encodes Nav1.6, a voltage-gated sodium channel alpha subunit expressed in CNS and PNS neurons but not cardiac or skeletal muscle, where loss of expression causes motor endplate disease, paralysis, and Purkinje cell degeneration [PMID:7670495]. Nav1.6 localizes to axon initial segments, nodes of Ranvier, and dendrites [PMID:10745220], where its rapid recovery from inactivation, use-dependent potentiation, and resistance to slow inactivation enable sustained high-frequency firing [PMID:12843211, PMID:15465873]. It is the principal source of resurgent and persistent sodium currents that drive pacemaking, fast spiking, and temporal precision of repetitive firing in central neurons, and its loss reduces sustained firing with compensatory upregulation of Nav1.1/Nav1.2 [PMID:16822974, PMID:18057213, PMID:20173079]. In sensory and inflamed peripheral neurons Nav1.6 underlies spontaneous bursting, mechanically-evoked spike initiation, and pain behaviors [PMID:19657055, PMID:23622763, PMID:25652923]. Channel function is set by an extensive regulatory network: calcium-independent and calcium-dependent calmodulin binding at the C-terminus controls current amplitude and inactivation [PMID:12967988]; phosphorylation by p38 MAPK at Ser553, by CaMKII at Ser561 and Ser641/Thr642, and JAK2-dependent phosphorylation of FGF14-Y158 tune current density and gating [PMID:16014723, PMID:32611770, PMID:32599005]; S-palmitoylation at Cys1169/Cys1170/Cys1978 modulates current and inactivation [PMID:32161114]; and surface trafficking requires the N-terminal Map1b interaction, the beta1 subunit, and APP [PMID:20133873, PMID:22474336, PMID:25767117]. RBFOX proteins direct inclusion of exon 18A required for functional full-length protein [PMID:22044765], and transcription is repressed by CDYL-recruited H3K27me3 and induced by TNF-alpha/STAT3-p300 acetylation or MAPK-ERK-CREB signaling [PMID:28842554, PMID:30736806, PMID:37453670]. Gain-of-function mutations elevate persistent and/or resurgent currents to cause neuronal hyperexcitability and epileptic encephalopathy, acting critically through excitatory neurons but also via depolarization block and inhibitory failure of SST and PV interneurons, while loss-of-function variants reduce firing; this disease link is established by knock-in mouse models, patient iPSC neurons, and antisense rescue [PMID:25227913, PMID:30601941, PMID:30615093, PMID:32968789, PMID:34544834, PMID:39435659, PMID:31943325].","teleology":[{"year":1995,"claim":"Established that SCN8A encodes a neuron-specific sodium channel whose loss is lethal, defining its identity and the consequence of deficiency.","evidence":"Positional cloning and transgene-induced deletion with tissue expression analysis in mice","pmids":["7670495"],"confidence":"High","gaps":["Did not define subcellular localization or biophysical properties","Mechanism linking channel loss to Purkinje degeneration unresolved"]},{"year":2000,"claim":"Resolved where Nav1.6 acts by localizing it to nodes of Ranvier, axon initial segments, and dendrites, linking the channel to action potential initiation and propagation.","evidence":"Isoform-specific immunohistochemistry in rat nervous system","pmids":["10745220"],"confidence":"High","gaps":["Localization mechanism not addressed","Functional consequence of dendritic localization untested"]},{"year":2003,"claim":"Provided the biophysical basis for Nav1.6-driven high-frequency firing through fast repriming and identified calmodulin as a direct C-terminal regulator of current and inactivation.","evidence":"Whole-cell patch clamp of recombinant channels in DRG neurons; GST pulldown, co-expression, and C-terminal mutagenesis","pmids":["12843211","12967988"],"confidence":"High","gaps":["Calmodulin's structural binding mode not defined","In vivo relevance of CaM modulation not tested"]},{"year":2004,"claim":"Explained why Nav1.6 sustains rather than dampens repetitive firing by demonstrating use-dependent potentiation arising from fast activation and slow-inactivation resistance.","evidence":"Patch clamp of Nav1.6 vs Nav1.2 with fast-inactivation-removed mutants in Xenopus oocytes","pmids":["15465873"],"confidence":"High","gaps":["Native neuron relevance addressed only later","Molecular determinants of slow-inactivation resistance not mapped"]},{"year":2005,"claim":"Opened post-translational regulation of Nav1.6 by identifying p38 MAPK phosphorylation at Ser553 that suppresses current without altering gating.","evidence":"In vitro kinase assay, S553A mutagenesis, patch clamp in p38-activated cells","pmids":["16014723"],"confidence":"High","gaps":["Physiological trigger of p38 regulation unclear","Whether reduction reflects trafficking or open probability not resolved"]},{"year":2006,"claim":"Demonstrated in vivo that Nav1.6 is required for sustained high-frequency firing and that other isoforms partially compensate at AIS and nodes.","evidence":"Patch clamp and immunofluorescence in retinal ganglion cells from null vs wild-type mice","pmids":["16822974"],"confidence":"High","gaps":["Compensation mechanism not defined","Persistent vs resurgent contributions not separated here"]},{"year":2007,"claim":"Attributed resurgent sodium current and pacemaking/fast-spiking to Nav1.6, defining its role in autonomous firing.","evidence":"Patch clamp in null GPe neurons plus computational modeling","pmids":["18057213"],"confidence":"High","gaps":["Molecular basis of resurgent current not addressed","Beta4/FHF dependency identified only later"]},{"year":2008,"claim":"Linked activity-dependent increases in Nav1.6 and persistent current to seizure circuit facilitation, an early connection to epileptogenesis.","evidence":"Immunocytochemistry, in situ hybridization, patch clamp and kindling in wild-type vs Nav1.6+/- mice","pmids":["18637833"],"confidence":"High","gaps":["Whether persistent current increase is cause or consequence of hyperactivity not separated","Cell-type specificity not resolved"]},{"year":2009,"claim":"Identified FGF14 splice variants and Nav1.6 mechanosensitivity, showing the channel is both a regulated complex member and a mechanically gated sodium leak.","evidence":"Co-expression patch clamp with FGF14 deletion mutants; mechanical stretch/aspiration with Na+ dye fluorimetry in heterologous cells","pmids":["19465131","19657055"],"confidence":"High","gaps":["Mechanotransduction structural mechanism unknown","In vivo significance of mechanosensitivity untested"]},{"year":2010,"claim":"Refined Nav1.6's firing role to persistent-current-dependent temporal precision and established beta1 as required for AIS localization and resurgent current.","evidence":"Conditional KO granule cell patch clamp; Scn1b-null AIS immunofluorescence, electrophysiology, and shRNA knockdown","pmids":["20173079","20133873"],"confidence":"High","gaps":["Beta1 targeting mechanism not molecularly defined","Interplay of beta1 with other trafficking partners unresolved"]},{"year":2011,"claim":"Clarified beta-subunit modulation as comparatively weak for Nav1.6, distinguishing its regulation from other isoforms.","evidence":"Co-expression of beta1-beta4 and beta-subunit chimeras in Xenopus oocytes with patch clamp","pmids":["21562192"],"confidence":"Medium","gaps":["Single heterologous system","Beta4 role in resurgent current not addressed here"]},{"year":2012,"claim":"Identified Map1b as an N-terminal trafficking partner essential for Nav1.6 surface current, mechanistically linking channel delivery to the cytoskeleton.","evidence":"Yeast two-hybrid, brain co-IP, alanine-scanning mutagenesis (residues 77-80), patch clamp","pmids":["22474336"],"confidence":"High","gaps":["Step in trafficking pathway affected not defined","Whether Map1b acts with beta1 or independently unknown"]},{"year":2013,"claim":"Demonstrated a causal role for Nav1.6 in peripheral pathological pain and ectopic bursting following inflammation.","evidence":"In vivo DRG siRNA knockdown with behavioral, single-unit, qPCR and IHC readouts in rat","pmids":["23622763"],"confidence":"High","gaps":["Whether effect is via persistent or resurgent current not separated","Upstream inflammatory regulation defined only later"]},{"year":2014,"claim":"Established gain-of-function as the disease mechanism in SCN8A epileptic encephalopathy via persistent-current and activation-shift mutations.","evidence":"N1768D knock-in mouse with EEG and dose-response; T767I mutagenesis with patch clamp in cells and neurons","pmids":["25227913","24874546"],"confidence":"High","gaps":["Critical cell type not yet identified","Connection from channel biophysics to network seizures not resolved here"]},{"year":2015,"claim":"Expanded the trafficking and signaling network controlling Nav1.6 by identifying APP-Go-JNK surface regulation, kinase control of the FGF14:Nav1.6 complex, and a peripheral spike-initiation role.","evidence":"Reciprocal co-IP, Go/JNK mutants and T668 mutagenesis with biotinylation; split-luciferase kinase screen with neuronal electrophysiology; selective Nav1.6 toxins in colon-nerve preparation","pmids":["25767117","25659151","25652923"],"confidence":"High","gaps":["GSK3/PI3K regulation acts indirectly through FGF14","In vivo significance of APP-Nav1.6 axis not tested at this stage"]},{"year":2016,"claim":"Connected gain-of-function mutations to elevated resurgent current, identified CDYL-H3K27me3 transcriptional repression, FHF2 isoform regulation of resurgent current, somatic nanocluster organization, and a pharmacological handle (cannabidiol).","evidence":"Mutant channel patch clamp with Navbeta4 peptide; ChIP and in vivo CDYL gain/loss-of-function; FHF2 chimeras and siRNA in DRG neurons; single-particle tracking/PALM imaging; M136V electrophysiology","pmids":["27267376","28842554","27999940","27653482","27496104"],"confidence":"High","gaps":["Nanocluster scaffolding identity beyond ankyrin-independence unknown","Resurgent current's molecular partner in vivo not fully defined"]},{"year":2017,"claim":"Localized seizure mechanisms to specific neuron types, showing both excitatory persistent-current elevation (with reverse NCX) and reticular thalamic inhibitory failure can drive distinct seizure phenotypes.","evidence":"N1768D knock-in cell-type patch clamp with TTX/riluzole/SN-6 pharmacology; conditional RT-cell and adult thalamic KO with EEG","pmids":["28193882","28238546"],"confidence":"High","gaps":["Relative contribution of excitatory vs inhibitory mechanisms to overall disease not weighed here","Reverse NCX role inferred pharmacologically"]},{"year":2019,"claim":"Pinpointed excitatory neurons as the critical pathogenic cell type for gain-of-function encephalopathy, distinguished gain- from loss-of-function and depolarization-block variants, and showed Nav1.6 promotes neuroinflammation after demyelination.","evidence":"Cell-type-specific Cre knock-in with EEG/survival; multi-variant patch clamp with computational modeling; AAV-Cre conditional deletion in EAE","pmids":["30601941","30615093","31722722"],"confidence":"High","gaps":["Inhibitory neuron contributions revisited in later work","EAE neuroinflammation mechanism is correlative/conditional, single lab"]},{"year":2020,"claim":"Mapped the post-translational control surface of Nav1.6 (CaMKII, S-palmitoylation, JAK2-FGF14) and demonstrated therapeutic transcript reduction by antisense oligonucleotides in two epilepsy models.","evidence":"Mass spectrometry, mutagenesis and patch clamp for CaMKII sites; acyl-biotin exchange and mutagenesis for palmitoylation; HTS, MS and FGF14Y158A patch clamp for JAK2; ICV ASO in R1872W and Scn1a+/- mice; patient iPSC neuron electrophysiology","pmids":["32611770","32161114","32599005","31943325","32968789"],"confidence":"High","gaps":["Integration of competing PTMs on the same channel pool not resolved","ASO long-term safety and cognitive effects not addressed"]},{"year":2021,"claim":"Demonstrated that gain-of-function in SST inhibitory interneurons paradoxically promotes seizures through depolarization block driven by persistent current.","evidence":"SST-Cre conditional knock-in with EEG, patch clamp, pharmacology, modeling and chemogenetics","pmids":["34544834"],"confidence":"High","gaps":["Relative weight of SST vs excitatory contributions in patients unclear","Mechanism of selective audiogenic susceptibility unresolved"]},{"year":2022,"claim":"Linked Nav1.6 to Alzheimer's pathology by showing hippocampal knockdown rescues cognition and lowers amyloid via a reverse-NCX/calcium/NFAT1/BACE1 axis.","evidence":"AAV-shRNA knockdown in APP/PS1 mice with behavioral, biochemical and calcium imaging readouts","pmids":["35353937"],"confidence":"Medium","gaps":["NFAT1-BACE1 pathway partially inferred, single lab","Direct demonstration of reverse NCX in vivo limited"]},{"year":2023,"claim":"Identified MAPK-ERK-CREB transcriptional induction of Nav1.6 as a driver of chemotherapy-induced neuropathic pain.","evidence":"ChIP for CREB at Scn8a promoter, kinase inhibitor pharmacology, qPCR and behavior in rats","pmids":["37453670"],"confidence":"Medium","gaps":["Single lab, single pain model","Crosstalk with other Scn8a transcriptional regulators not examined"]},{"year":2024,"claim":"Showed that PV interneuron gain-of-function alone causes spontaneous lethal seizures and that splice-isoform and TTX-resistance context shape variant phenotypes, refining genotype-phenotype interpretation.","evidence":"PV-Cre conditional knock-in with EEG and synaptic/intrinsic electrophysiology; automated patch clamp of 15 variants across two isoforms in engineered low-Nav cells","pmids":["39435659","38771640"],"confidence":"High","gaps":["Combined effect of excitatory and multiple interneuron classes in patients not modeled","Physiological role of neonatal vs adult isoform switch not defined"]},{"year":null,"claim":"How the many parallel regulatory inputs (phosphorylation, palmitoylation, accessory subunits, trafficking partners, and transcriptional/epigenetic control) are coordinated on a single Nav1.6 channel pool to set excitability in specific neuron types remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No integrated model of competing PTMs and partners on the same channel","Structural basis of resurgent current and nanocluster scaffolding undefined","Cell-type-specific therapeutic targeting not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,2,5,8,11,12]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[11]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,11,19,25]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[1,15]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[2,7,8,12]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[17,28,29,35,36,39]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[14,24,30,38]}],"complexes":[],"partners":["CALM","FGF14","MAP1B","SCN1B","APP","SCN4B","FHF2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UQD0","full_name":"Sodium channel protein type 8 subunit alpha","aliases":["Sodium channel protein type VIII subunit alpha","Voltage-gated sodium channel subunit alpha Nav1.6"],"length_aa":1980,"mass_kda":225.3,"function":"Pore-forming subunit of a voltage-gated sodium channel complex assuming opened or closed conformations in response to the voltage difference across membranes and through which sodium ions selectively pass along their electrochemical gradient (PubMed:24874546, PubMed:25239001, PubMed:25725044, PubMed:26900580, PubMed:29726066, PubMed:33245860, PubMed:36696443, PubMed:36823201). Contributes to neuronal excitability by regulating action potential threshold and propagation (PubMed:24874546, PubMed:25239001, PubMed:25725044, PubMed:26900580, PubMed:29726066, PubMed:33245860, PubMed:36696443, PubMed:36823201) More specifically expressed in non-neuronal cells, could play a role in sodium release from intracellular compartments and participate in the control of podosomes formation and macrophages adhesion and movement","subcellular_location":"Cytoplasmic vesicle; Cell projection, podosome","url":"https://www.uniprot.org/uniprotkb/Q9UQD0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SCN8A","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SCN8A","total_profiled":1310},"omim":[{"mim_id":"618428","title":"POPOV-CHANG SYNDROME; POPCHAS","url":"https://www.omim.org/entry/618428"},{"mim_id":"618364","title":"MYOCLONUS, FAMILIAL, 2; MYOCL2","url":"https://www.omim.org/entry/618364"},{"mim_id":"617080","title":"SEIZURES, BENIGN FAMILIAL INFANTILE, 5; BFIS5","url":"https://www.omim.org/entry/617080"},{"mim_id":"614937","title":"MYOCLONUS, FAMILIAL, 1; MYOCL1","url":"https://www.omim.org/entry/614937"},{"mim_id":"614558","title":"DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY 13; DEE13","url":"https://www.omim.org/entry/614558"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Plasma membrane","reliability":"Approved"},{"location":"Vesicles","reliability":"Additional"},{"location":"Cell Junctions","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":16.9},{"tissue":"pituitary gland","ntpm":6.3},{"tissue":"retina","ntpm":7.3}],"url":"https://www.proteinatlas.org/search/SCN8A"},"hgnc":{"alias_symbol":["Nav1.6","NaCh6","PN4","CerIII","CIAT"],"prev_symbol":["MED"]},"alphafold":{"accession":"Q9UQD0","domains":[{"cath_id":"1.20.120.350","chopping":"732-848","consensus_level":"high","plddt":83.213,"start":732,"end":848},{"cath_id":"1.20.120","chopping":"1164-1209_1237-1307","consensus_level":"high","plddt":81.5896,"start":1164,"end":1307},{"cath_id":"1.10.287.70","chopping":"1328-1354_1393-1470","consensus_level":"medium","plddt":87.3436,"start":1328,"end":1470},{"cath_id":"-","chopping":"1356-1391","consensus_level":"medium","plddt":83.26,"start":1356,"end":1391},{"cath_id":"1.20.120.350","chopping":"1510-1634","consensus_level":"high","plddt":82.038,"start":1510,"end":1634},{"cath_id":"1.10.238.10","chopping":"1779-1906","consensus_level":"medium","plddt":75.5886,"start":1779,"end":1906}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UQD0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UQD0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UQD0-F1-predicted_aligned_error_v6.png","plddt_mean":68.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SCN8A","jax_strain_url":"https://www.jax.org/strain/search?query=SCN8A"},"sequence":{"accession":"Q9UQD0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UQD0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UQD0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UQD0"}},"corpus_meta":[{"pmid":"7670495","id":"PMC_7670495","title":"Mutation of a new sodium channel gene, Scn8a, in the mouse mutant 'motor endplate disease'.","date":"1995","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7670495","citation_count":267,"is_preprint":false},{"pmid":"12843211","id":"PMC_12843211","title":"Distinct repriming and closed-state inactivation kinetics of Nav1.6 and Nav1.7 sodium channels in mouse spinal sensory neurons.","date":"2003","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/12843211","citation_count":258,"is_preprint":false},{"pmid":"25568300","id":"PMC_25568300","title":"The phenotypic spectrum of SCN8A encephalopathy.","date":"2015","source":"Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/25568300","citation_count":238,"is_preprint":false},{"pmid":"14662515","id":"PMC_14662515","title":"Co-localization of sodium channel Nav1.6 and the sodium-calcium exchanger at sites of axonal injury in the spinal cord in EAE.","date":"2003","source":"Brain : a journal of 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motor endplate disease (med) phenotype including progressive paralysis, muscle atrophy, Purkinje cell degeneration, and juvenile lethality in mice.\",\n      \"method\": \"Positional cloning, transgene-induced deletion, expression analysis (tissue Northern blot)\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — positional cloning with functional validation of loss-of-expression allele, replicated across multiple subsequent studies\",\n      \"pmids\": [\"7670495\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Nav1.6 (NaCh6) protein localizes to nodes of Ranvier in peripheral nerve and spinal cord, axon initial segments, dendrites of pyramidal cells, and motor neuron axons; it is the first sodium channel isoform localized to both nodes of Ranvier and dendrites.\",\n      \"method\": \"Immunohistochemistry with isoform-specific antibodies in rat nervous system sections\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct protein localization with isoform-specific antibodies, replicated by multiple subsequent studies\",\n      \"pmids\": [\"10745220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Recombinant Nav1.6 channels exhibit approximately 5-fold faster recovery from inactivation (repriming) and faster development of closed-state inactivation compared to Nav1.7, providing a molecular basis for high-frequency firing in large myelinated DRG neurons.\",\n      \"method\": \"Whole-cell patch clamp of recombinant Nav1.6 and Nav1.7 expressed in mouse DRG neurons\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological characterization in native neuronal context with quantitative comparison, single lab but rigorous\",\n      \"pmids\": [\"12843211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Calmodulin (CaM) binds to the C-terminal domain of Nav1.6 in a calcium-independent manner; disrupting this interaction reduced Nav1.6 current amplitude by 62%, and CaM also modulates Nav1.6 inactivation kinetics in a calcium-dependent manner.\",\n      \"method\": \"GST-fusion protein pulldown, co-expression with CaM in transfected cells, whole-cell patch clamp, C-terminal mutagenesis\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro binding assay combined with mutagenesis and functional electrophysiology; calcium-independent binding and calcium-dependent modulation distinguished\",\n      \"pmids\": [\"12967988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In EAE (experimental autoimmune encephalomyelitis), Nav1.6 co-localizes with the Na+/Ca2+ exchanger (NCX) along demyelinated axons; 73.5% of injured (beta-APP positive) axons co-express Nav1.6 and NCX, suggesting that Nav1.6-mediated sodium influx drives reverse NCX operation and calcium-mediated axonal degeneration.\",\n      \"method\": \"Triple-label fluorescent immunohistochemistry in mouse EAE spinal cord\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — co-localization by immunohistochemistry without direct functional test of the proposed mechanism, but replicated in subsequent MS studies\",\n      \"pmids\": [\"14662515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Nav1.6 channels exhibit use-dependent potentiation (increased current) during rapid repetitive depolarizations, in contrast to Nav1.2 which shows use-dependent decrease; this results from faster channel activation and resistance to slow inactivation in Nav1.6.\",\n      \"method\": \"Whole-cell patch clamp of Nav1.6 and Nav1.2 co-expressed with beta1 in Xenopus oocytes; fast inactivation-removed mutant channels used to dissect mechanism\",\n      \"journal\": \"Biophysical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mutagenesis to remove fast inactivation, mechanistic dissection of potentiation vs. slow inactivation\",\n      \"pmids\": [\"15465873\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"p38 MAP kinase (p38alpha) phosphorylates Nav1.6 specifically at serine 553 within cytoplasmic loop L1 (joining domains 1 and 2); activation of p38 in neuronal cells significantly reduces Nav1.6 peak current amplitude without affecting gating; S553A substitution prevents this p38-mediated reduction.\",\n      \"method\": \"In vitro kinase assay with GST-fusion fragments of Nav1.6, site-directed mutagenesis (S553A), whole-cell patch clamp in p38-activated ND7/23 cells transfected with Nav1.6\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro kinase assay identifying specific phosphorylation site, confirmed by mutagenesis and functional electrophysiology\",\n      \"pmids\": [\"16014723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Nav1.6 is required for repetitive high-frequency firing in retinal ganglion cells (RGCs); in Nav1.6-null (med) mice, maximal sustained and instantaneous firing rates are reduced by postnatal day 18. Compensatory upregulation of Nav1.2 and Nav1.1 at axon initial segments and nodes occurs in a cell-type-specific manner.\",\n      \"method\": \"Whole-cell patch clamp recordings from RGCs during postnatal development in med vs. wild-type mice; immunofluorescence for sodium channel isoforms at AIS and nodes\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO phenotype with direct electrophysiological readout, complemented by immunolocalization, replicated across multiple cell types\",\n      \"pmids\": [\"16822974\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Nav1.6 channels underlie resurgent sodium current in globus pallidus (GPe) neurons; Nav1.6-null GPe neurons show significantly reduced resurgent current, impaired pacemaking and fast spiking, and inability to follow high-frequency stimulation.\",\n      \"method\": \"Whole-cell patch clamp in acutely isolated GPe neurons from Nav1.6-null mice; computational modeling\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO neurons with direct electrophysiological phenotype, resurgent current attribution confirmed by null comparison and modeling\",\n      \"pmids\": [\"18057213\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Nav1.6 expression and persistent sodium current increase selectively in hippocampal CA3 neurons following kindling; heterozygous Nav1.6-deficient mice (Nav1.6+/-) resist initiation and development of kindling, identifying Nav1.6 as a participant in activity-dependent facilitation in hippocampal circuits.\",\n      \"method\": \"Immunocytochemistry, in situ hybridization, patch clamp recordings, kindling behavioral analysis in wild-type vs. Nav1.6+/- mice\",\n      \"journal\": \"Epilepsia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (protein, mRNA, current, behavior), genetic reduction with defined functional phenotype\",\n      \"pmids\": [\"18637833\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"FGF14 N-terminal splice variants (FGF14-1a and FGF14-1b) differentially regulate Nav1.6 currents: FGF14-1b (but not FGF14-1a) attenuates Nav1.6 current density; an FGF14 mutant lacking the N-terminus increases Nav1.6 current density; the N-terminus is required for axon initial segment targeting of FGF14.\",\n      \"method\": \"Co-expression in neurons with patch clamp, immunofluorescence localization in neurons, deletion mutagenesis\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional electrophysiology with deletion mutagenesis and localization data, single lab\",\n      \"pmids\": [\"19465131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Mechanical membrane trauma (bleb-inducing aspiration or uniaxial stretch) causes Nav1.6 channels to exhibit irreversible hyperpolarizing shifts in steady-state inactivation and activation, expanding window current; stretch of Nav1.6-expressing HEK cells causes tetrodotoxin-sensitive cytoplasmic Na+ increase, demonstrating Nav1.6 acts as a mechanosensitive sodium leak channel.\",\n      \"method\": \"Patch clamp of recombinant Nav1.6 in oocyte patches (cell-attached aspiration) and HEK cells (substrate stretch); Na+-dye fluorimetry\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological measurement of channel response to defined mechanical stimuli, TTX-sensitive Na+ influx confirmed by dye imaging\",\n      \"pmids\": [\"19657055\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Nav1.6 at axon initial segments contributes to persistent (but not transient or resurgent) sodium current in cerebellar granule cells; loss of Nav1.6 at AIS leads to faster action potential repolarization, larger post-spike hyperpolarization, and increased interspike-interval variability, demonstrating a role in temporal precision of repetitive firing.\",\n      \"method\": \"Whole-cell patch clamp of acute cerebellar slices and acutely dissociated granule cells from granule cell-specific Scn8a conditional KO mice; immunofluorescence for Nav subunits\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with direct electrophysiological characterization distinguishing persistent from transient and resurgent currents\",\n      \"pmids\": [\"20173079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Beta1 (Scn1b) subunit is required for normal Nav1.6 localization at the axon initial segment during postnatal development; in Scn1b-null cerebellar granule neurons, Nav1.6 at AIS is reduced and Nav1.1 substitutes; beta1-mediated neurite outgrowth requires Nav1.6-mediated sodium current, and Nav1.6 resurgent current is reduced in Scn1b-null neurons.\",\n      \"method\": \"Immunofluorescence of AIS in Scn1b-null cerebellar neurons, whole-cell patch clamp recording of resurgent current, shRNA knockdown of Nav1.6\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional interaction demonstrated by KO, immunolocalization, and electrophysiology with multiple orthogonal methods\",\n      \"pmids\": [\"20133873\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Rbfox proteins (Fox-1 and Fox-2) regulate alternative splicing of SCN8A by promoting inclusion of exon 18A over exon 18N; exon 18A selection is dependent on a Fox consensus binding site 28 bp downstream of exon 18A; exon 18A is required for production of functional full-length Nav1.6 protein.\",\n      \"method\": \"Scn8a minigene co-transfection with Fox-1 or Fox-2; mutagenesis of Fox binding site; RT-PCR of purified cell populations (neurons vs. glia)\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — minigene splicing assay with binding site mutagenesis, single lab with multiple orthogonal validations\",\n      \"pmids\": [\"22044765\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The N-terminal domain of Nav1.6 (residues 1-153) interacts with the light chain of microtubule-associated protein Map1b; residues 77-80 (VAVP) contribute to this interaction; Map1b co-immunoprecipitates with endogenous Nav1.6 from mouse brain; co-expression of Map1b with Nav1.6 increases current density ~50%; mutation of the Map1b binding site prevents sodium current generation, establishing Map1b as a trafficking partner for Nav1.6.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation from mouse brain, alanine-scanning mutagenesis, whole-cell patch clamp in ND7/23 cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — yeast two-hybrid confirmed by co-IP from brain, mutagenesis identifies binding residues, functional electrophysiology validates consequence\",\n      \"pmids\": [\"22474336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In vivo knockdown of Nav1.6 in rat lumbar DRG via siRNA completely blocked development of mechanical pain behaviors and abnormal spontaneous bursting activity following local DRG inflammation; cells capable of repetitive firing had higher Nav1.6 expression, and spontaneously active bursting cells in inflamed DRG expressed high Nav1.6 immunoreactivity.\",\n      \"method\": \"In vivo siRNA knockdown, behavioral pain testing (paw withdrawal threshold), single-unit electrophysiology, qPCR and immunohistochemistry\",\n      \"journal\": \"Pain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo loss-of-function with defined behavioral and electrophysiological readouts, multiple methods in single study\",\n      \"pmids\": [\"23622763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The de novo SCN8A mutation p.Asn1768Asp (N1768D) results in increased persistent sodium current and neuronal hyperactivity; knock-in mice carrying this mutation exhibit seizures, SUDEP, and EEG-confirmed ictal discharges; severity scales with mutant protein dose (heterozygous < hemizygous < homozygous).\",\n      \"method\": \"Knock-in mouse model, video/EEG analysis, behavioral testing, transfected cell electrophysiology\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knock-in model with EEG confirmation, dose-response genetic analysis (het/hemi/homo), replicated by multiple subsequent studies\",\n      \"pmids\": [\"25227913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The de novo SCN8A mutation p.Thr767Ile causes enhanced channel activation with a 10 mV depolarizing shift in voltage dependence, increased ramp current, and increased spontaneous firing with paroxysmal depolarizing shift-like complexes in hippocampal neurons, establishing a gain-of-function mechanism for epilepsy.\",\n      \"method\": \"Site-directed mutagenesis, whole-cell patch clamp in transfected neuronal cells and hippocampal pyramidal neurons\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — electrophysiology in both heterologous system and primary neurons, mutagenesis, single lab\",\n      \"pmids\": [\"24874546\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Amyloid precursor protein (APP) co-localizes and interacts with Nav1.6 in mouse cortical neurons; APP knockdown decreases Nav1.6 currents and cell surface expression; APP increases Nav1.6 surface expression through a Go protein-dependent, JNK-mediated pathway; phosphorylation of APP at Thr668 by JNK enhances APP-Nav1.6 interaction and Nav1.6 surface expression.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, dominant-active/negative Go mutants, JNK inhibitors, T668E/T668A mutagenesis, whole-cell patch clamp, surface biotinylation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reciprocal co-IP plus mutagenesis plus functional electrophysiology plus pharmacological dissection in single study\",\n      \"pmids\": [\"25767117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"The PI3K/Akt pathway, Wee1 kinase, and protein kinase C (PKC) regulate the FGF14:Nav1.6 protein-protein interaction complex; inhibition of GSK3 (a convergence point of these pathways) impairs excitability of hippocampal neurons.\",\n      \"method\": \"Split-luciferase complementation assay in live cells screening 12 kinase inhibitor pathways; dose-response validation; hippocampal neuron electrophysiology\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — LCA assay with pharmacological inhibitors, validated by neuronal electrophysiology, but mechanism is indirect (through FGF14 interaction) and single lab\",\n      \"pmids\": [\"25659151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Nav1.6 is required for spike initiation at stretch-sensitive colorectal afferent endings; selective Nav1.6 antagonists (mu-conotoxin GIIIa and PIIIa) significantly reduced afferent responses to colorectal stretch, while Nav1.7 or Nav1.8 antagonists did not; computational modeling confirmed Nav1.6 is necessary for tonic spiking at sensory endings.\",\n      \"method\": \"In vitro colon-nerve preparation with selective toxin pharmacology, immunohistochemistry/Western blot, computational modeling\",\n      \"journal\": \"Journal of neurophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — isoform-selective pharmacology with negative controls for other isoforms, supported by computational modeling\",\n      \"pmids\": [\"25652923\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Epilepsy-associated Nav1.6 mutations N1768D and L1331V dramatically increase resurgent sodium currents; cannabidiol preferentially inhibits resurgent and persistent sodium currents from wild-type and mutant Nav1.6 over peak transient currents; this inhibition reduces action potential firing in striatal neurons.\",\n      \"method\": \"Whole-cell patch clamp in HEK293T cells with Navβ4 peptide to induce resurgent current; Nav1.6 mutant channels; current clamp in striatal neurons\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct channel electrophysiology with disease mutations, pharmacological dissection of current subtypes, confirmed in native neurons\",\n      \"pmids\": [\"27267376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The SCN8A gain-of-function mutation p.Met136Val increases peak current density (~1.5-fold) and resurgent current (~1.6-fold) without altering gating properties; it increases the fraction of high-firing neurons, lowers current threshold, and increases action potential frequency in trigeminal ganglion neurons.\",\n      \"method\": \"Whole-cell voltage clamp in transfected cells, current clamp in trigeminal ganglion neurons\",\n      \"journal\": \"Molecular medicine (Cambridge, Mass.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — electrophysiology in both heterologous and native neuron contexts, single lab\",\n      \"pmids\": [\"27496104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CDYL (Chromodomain Y-like) epigenetic factor binds a regulatory element in the intron of SCN8A and recruits H3K27me3 activity to repress Nav1.6 transcription; CDYL knockdown in hippocampal neurons augments Nav1.6 currents and lowers seizure threshold; CDYL overexpression raises neuronal threshold and reduces epileptogenesis.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), co-immunoprecipitation, siRNA knockdown, transgenic overexpression, patch clamp recordings, seizure susceptibility testing in mice\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP identifies direct binding to SCN8A intron, functional consequence confirmed by both loss- and gain-of-function in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"28842554\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Nav1.6 somatic nanoclusters (~230 nm diameter) exist on the surface of hippocampal neuron soma that are stable for >30 minutes via an ankyrin-independent mechanism; non-clustered Nav1.6 channels show anomalous diffusion and can be transiently trapped in nanoclusters.\",\n      \"method\": \"Single-particle tracking, photoactivation localization microscopy (PALM), mean-square displacement analysis, Bayesian inference analysis\",\n      \"journal\": \"Biophysical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct single-molecule imaging with multiple analytical methods, ankyrin independence established\",\n      \"pmids\": [\"27653482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Loss of Scn8a in reticular thalamic (RT) neurons alters intrinsic RT cell excitability and causes failure in recurrent RT-RT synaptic inhibition, leading to enhanced thalamocortical network synchrony and absence epilepsy (spike-wave discharges); deletion of Scn8a in adult thalamus alone is sufficient to generate spike-wave discharges.\",\n      \"method\": \"Conditional KO (Cre-dependent deletion in RT cells), EEG recording, patch clamp in thalamic slices, adult-specific deletion\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell type-specific and adult-specific conditional KO with direct EEG and electrophysiological measurements of two distinct mechanisms\",\n      \"pmids\": [\"28238546\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Gain-of-function SCN8A mutation p.Asn1768Asp (N1768D) increases persistent sodium current density selectively in hippocampal CA1 pyramidal neurons (not bipolar neurons) and CA3 pyramidal and bipolar neurons; CA1 pyramidal neurons show early afterdepolarization-like action potential waveforms blocked by TTX, riluzole, and reverse Na/Ca exchange inhibitor SN-6, implicating elevated persistent INa and reverse NCX in hyperexcitability.\",\n      \"method\": \"Patch clamp of acutely dissociated neurons and brain slices from Scn8a N1768D knock-in mice; pharmacological dissection with TTX, riluzole, SN-6\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — knock-in model with cell-type-specific analysis, pharmacological mechanism dissection, multiple orthogonal approaches\",\n      \"pmids\": [\"28193882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Restricting expression of the gain-of-function SCN8A mutation p.Arg1872Trp to excitatory neurons (via Emx1-Cre) recapitulates seizures and juvenile lethality; expression in inhibitory neurons (Gad2-Cre or Dlx5/6-Cre) does not induce seizures, establishing excitatory neurons as the critical cell type for SCN8A encephalopathy pathogenesis.\",\n      \"method\": \"Conditional knock-in mouse model with neuron-type-specific Cre drivers (Emx1-Cre, Gad2-Cre, Dlx5/6-Cre); EEG monitoring; survival analysis\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific conditional expression with multiple Cre drivers and EEG confirmation, clear positive (excitatory) and negative (inhibitory) results\",\n      \"pmids\": [\"30601941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Multiple SCN8A epilepsy mutations (E1483K, R1872W) increase neuronal firing in primary neuronal cultures; loss-of-function mutations (R1620L) reduce neuronal firing; A1622D dramatically slows fast inactivation and induces depolarization block reducing neuronal firing despite epileptic presentation, confirming distinct genotype-phenotype correlations.\",\n      \"method\": \"Whole-cell patch clamp in neuroblastoma cells and primary cultured neurons; current clamp in neurons; computational modeling\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — electrophysiology in two independent systems (cell line + neurons) for 7 mutations with computational validation, reveals mechanism of depolarization block\",\n      \"pmids\": [\"30615093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TNF-α/STAT3 signaling upregulates Nav1.6 in DRG neurons: STAT3 binds the Scn8a promoter, interacts with p300, and promotes histone H4 hyperacetylation at the Scn8a promoter region, leading to increased Nav1.6 transcription following L5 ventral root transection; TNF-α inhibition reduces STAT3 recruitment and Nav1.6 upregulation.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP), co-immunoprecipitation (STAT3-p300), qPCR, Western blot, in vivo pharmacology\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP directly demonstrates STAT3 binding to Scn8a promoter, co-IP for STAT3-p300 interaction, pharmacological rescue, multiple methods\",\n      \"pmids\": [\"30736806\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Scn8a antisense oligonucleotide (ASO) treatment reducing Scn8a transcript by 25-50% delays seizure onset and lethality in the Scn8a-R1872W mouse model in a dose-dependent manner; a single Scn8a ASO treatment also extends survival of Dravet syndrome (Scn1a+/-) mice from 3 weeks to >5 months.\",\n      \"method\": \"Intracerebroventricular ASO injection in conditional Scn8a-R1872W knock-in mice and Scn1a+/- mice; EEG recording; survival analysis; open field and wheel running assays\",\n      \"journal\": \"Annals of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — dose-dependent in vivo rescue with EEG confirmation, tested in two independent mouse models\",\n      \"pmids\": [\"31943325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CaMKII phosphorylates Nav1.6 at Ser-561 and Ser-641/Thr-642 within the first intracellular loop; CaMKII inhibition reduces Nav1.6 transient and persistent currents by ~72% and causes a 5.8 mV depolarizing shift in activation; S561A and S641A/T642A substitutions recapitulate these effects, demonstrating CaMKII modulates Nav1.6 channel activity.\",\n      \"method\": \"CaMKII-specific inhibitor CN21, whole-cell voltage clamp in Purkinje neurons and ND7/23/HEK293 cells, immobilized peptide arrays, LC-MS/MS phosphoproteomics, site-directed mutagenesis, computational modeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mass spectrometry identifies phosphorylation sites, mutagenesis confirms functional roles, electrophysiology in native and heterologous systems\",\n      \"pmids\": [\"32611770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Nav1.6 undergoes S-palmitoylation in mouse brain at three sites (Cys1169, Cys1170, Cys1978); enhancing palmitoylation increases Nav1.6 current while blocking it reduces current and shifts steady-state inactivation; Cys1978 is exclusive to Nav1.6 among all Nav isoforms and its palmitoylation specifically regulates current amplitude; loss of S-palmitoylation at specific sites alters neuronal excitability in DRG neurons.\",\n      \"method\": \"Acyl-biotin exchange assay in mouse brain and HEK cells, whole-cell voltage clamp with palmitic acid and 2-bromopalmitate, site-directed mutagenesis, current clamp in DRG neurons\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — biochemical detection of palmitoylation in vivo, site-specific mutagenesis, pharmacological modulation, functional confirmation in native neurons\",\n      \"pmids\": [\"32161114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"JAK2 phosphorylates FGF14 at Y158, a site that mediates both FGF14 homodimerization and FGF14:Nav1.6 complex formation; JAK2 inhibition increases FGF14 homodimerization while decreasing FGF14:Nav1.6 interaction; through Y158, JAK2 controls FGF14-dependent modulation of Nav1.6 channels; JAK2 inhibitor Fedratinib reduces hippocampal CA1 firing in a FGF14-dependent manner.\",\n      \"method\": \"High-throughput screening (split-luciferase), in vitro phosphorylation, mass spectrometry, FGF14Y158A mutagenesis, patch clamp electrophysiology in hippocampal neurons\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — MS identifies phosphorylation site, mutagenesis validates specificity, functional electrophysiology with genetic dependency confirmed\",\n      \"pmids\": [\"32599005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Patient iPSC-derived neurons from SCN8A-related epilepsy exhibit variant-specific alterations: mutations p.R1872L and p.V1592L show elevated persistent current, while p.N1759S shows increased resurgent current; all three patient neuron lines have shorter axon initial segment lengths and prolonged action potential repolarization compared to controls.\",\n      \"method\": \"Patient iPSC-derived excitatory neurons, whole-cell patch clamp, immunofluorescence for AIS length (ankyrin-G staining), MEA network activity\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient-specific iPSC model with electrophysiology revealing variant-specific mechanisms, multiple orthogonal methods\",\n      \"pmids\": [\"32968789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Selective expression of gain-of-function SCN8A mutation R1872W in somatostatin (SST) interneurons confers audiogenic seizure susceptibility; SST interneurons from mutant mice are hyperexcitable but hypersensitive to depolarization block; aberrantly large persistent sodium currents contribute directly to SST dysfunction; GqDREADD activation of WT SST interneurons also produces prolonged electrographic seizures.\",\n      \"method\": \"Cre-dependent conditional knock-in (SST-Cre), EEG, patch clamp electrophysiology, pharmacology, computational modeling, chemogenetics (GqDREADD)\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific conditional expression, electrophysiology identifying persistent current mechanism, pharmacological and chemogenetic validation\",\n      \"pmids\": [\"34544834\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Reducing Nav1.6 expression in hippocampus (via shRNA AAV) rescues cognitive impairments and attenuates synaptic deficits in APP/PS1 Alzheimer's model mice; Nav1.6 knockdown reduces Aβ levels by suppressing BACE1 transcription through a mechanism involving reduced intracellular calcium overload (via suppressed reverse NCX), increased inactive NFAT1, and thereby decreased BACE1 transcription.\",\n      \"method\": \"AAV-shRNA hippocampal injection, behavioral tests (Morris water maze), amyloid plaque quantification, ELISA, Western blot, calcium imaging\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo knockdown with multiple functional readouts, but proposed NFAT1-BACE1 pathway is partially inferred; single lab\",\n      \"pmids\": [\"35353937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The MAPK-ERK-CREB signaling pathway upregulates Nav1.6 (Scn8a) transcription in DRG during oxaliplatin-induced neuropathic pain; activated p-CREB directly binds the Scn8a promoter region as demonstrated by ChIP; inhibition of CREB reduces Nav1.6 mRNA and protein and alleviates pain.\",\n      \"method\": \"Western blot, RT-qPCR, ChIP, immunofluorescence, in vivo kinase inhibitor pharmacology in rats\",\n      \"journal\": \"Toxicology letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP directly demonstrates CREB binding to Scn8a promoter, pharmacological intervention confirms pathway, single lab\",\n      \"pmids\": [\"37453670\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Selective expression of gain-of-function SCN8A variant R1872W in parvalbumin (PV) interneurons is sufficient to cause spontaneous seizures and seizure-induced death; PV interneurons from mutant mice show increased persistent sodium current, susceptibility to depolarization block, and reduced inhibitory synaptic transmission onto pyramidal cells.\",\n      \"method\": \"PV-Cre conditional knock-in, EEG, patch clamp electrophysiology (persistent current, evoked firing, IPSCs in pyramidal cells)\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific conditional knock-in with EEG, electrophysiology of intrinsic and synaptic properties, identifying both intrinsic and circuit mechanisms\",\n      \"pmids\": [\"39435659\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SCN8A alternative splicing isoforms (neonatally expressed NaV1.6N vs. adult NaV1.6A) show small but significant differences in voltage dependence; many disease-associated variants exhibit isoform-dependent functional effects; TTX-resistant versions of both isoforms show significant functional differences from WT channels, highlighting the importance of molecular context in variant characterization.\",\n      \"method\": \"Automated patch clamp in ND7/LoNav cells (engineered low-endogenous-Nav cell line), comparison of 15 variants in two splice isoforms with and without TTX-resistance mutations\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic functional comparison of splice isoforms and disease variants using improved cell model, high-throughput electrophysiology, single lab\",\n      \"pmids\": [\"38771640\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Beta-subunit regulation of Nav1.6 is weak compared to Nav1.8; the beta4-subunit induces a hyperpolarizing shift in Nav1.6 activation (-7.6 mV) but does not alter inactivation or current density; the intracellular C-terminal domain of the beta1-subunit is essential for strong regulation of Nav1.8 but not Nav1.6.\",\n      \"method\": \"Co-expression of Nav1.6 with beta1-beta4 subunits in Xenopus oocytes, whole-cell patch clamp, beta-subunit chimera analysis\",\n      \"journal\": \"Journal of neurophysiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic co-expression electrophysiology with chimeras identifying functional domain, single lab, some negative results mechanistically informative\",\n      \"pmids\": [\"21562192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"FHF2 isoforms differentially regulate Nav1.6-mediated resurgent currents in DRG neurons: FHF2A enhances long-term inactivation and negatively regulates fast resurgent current; FHF2B lacks this long-term inactivation enhancement and positively regulates resurgent current; FHF2A and FHF2B expression are differentially regulated in a radicular pain model.\",\n      \"method\": \"Patch clamp electrophysiology in DRG neurons and cell lines; FHF2A/Navβ4 chimeric constructs; FHF2 isoform-specific siRNA knockdown\",\n      \"journal\": \"Pflugers Archiv : European journal of physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with chimeric constructs in native neurons, single lab, identifies differential gating mechanism\",\n      \"pmids\": [\"27999940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Nav1.6 deletion from retinal ganglion cells (via AAV-Cre in Scn8a-floxed mice) during EAE reduces pro-inflammatory cytokines (IL-6, IFN-γ) and reactive gliosis marker (GFAP) expression, reduces macrophage infiltration in targeted optic nerves, and improves axonal health, demonstrating Nav1.6 promotes neuroinflammation and axonal degeneration following demyelination.\",\n      \"method\": \"AAV-Cre conditional deletion in floxed Scn8a mice during EAE, gene expression analysis, immunohistochemistry, contralateral eye controls\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional cell-type-specific deletion with multiple outcome measures, single lab, intra-animal control\",\n      \"pmids\": [\"31722722\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SCN8A encodes Nav1.6, a voltage-gated sodium channel alpha subunit highly expressed at axon initial segments and nodes of Ranvier in the CNS and PNS, where it is essential for repetitive high-frequency firing, resurgent and persistent sodium currents, and action potential generation; its activity is regulated by multiple post-translational mechanisms including phosphorylation by p38 MAPK (at S553), CaMKII (at S561, S641/T642), and JAK2 (via FGF14-Y158), S-palmitoylation (at C1169, C1170, C1978), and calcium-dependent and independent calmodulin binding at the C-terminus; trafficking to the cell surface requires interaction with Map1b (via N-terminal residues 77-80) and beta1 subunit, and alternative splicing of exon 18A is controlled by RBFOX proteins to produce functional protein; transcription of SCN8A is epigenetically repressed by CDYL-H3K27me3 and can be upregulated by TNF-α/STAT3-p300 histone acetylation or MAPK-ERK-CREB signaling; gain-of-function mutations increase persistent and/or resurgent currents causing neuronal hyperexcitability and epileptic encephalopathy, primarily through excitatory neurons but also via failure of SST and PV inhibitory interneurons (depolarization block and synaptic transmission deficits), while loss-of-function causes intellectual disability and movement disorders.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SCN8A encodes Nav1.6, a voltage-gated sodium channel alpha subunit expressed in CNS and PNS neurons but not cardiac or skeletal muscle, where loss of expression causes motor endplate disease, paralysis, and Purkinje cell degeneration [#0]. Nav1.6 localizes to axon initial segments, nodes of Ranvier, and dendrites [#1], where its rapid recovery from inactivation, use-dependent potentiation, and resistance to slow inactivation enable sustained high-frequency firing [#2, #5]. It is the principal source of resurgent and persistent sodium currents that drive pacemaking, fast spiking, and temporal precision of repetitive firing in central neurons, and its loss reduces sustained firing with compensatory upregulation of Nav1.1/Nav1.2 [#7, #8, #12]. In sensory and inflamed peripheral neurons Nav1.6 underlies spontaneous bursting, mechanically-evoked spike initiation, and pain behaviors [#11, #16, #21]. Channel function is set by an extensive regulatory network: calcium-independent and calcium-dependent calmodulin binding at the C-terminus controls current amplitude and inactivation [#3]; phosphorylation by p38 MAPK at Ser553, by CaMKII at Ser561 and Ser641/Thr642, and JAK2-dependent phosphorylation of FGF14-Y158 tune current density and gating [#6, #32, #34]; S-palmitoylation at Cys1169/Cys1170/Cys1978 modulates current and inactivation [#33]; and surface trafficking requires the N-terminal Map1b interaction, the beta1 subunit, and APP [#13, #15, #19]. RBFOX proteins direct inclusion of exon 18A required for functional full-length protein [#14], and transcription is repressed by CDYL-recruited H3K27me3 and induced by TNF-alpha/STAT3-p300 acetylation or MAPK-ERK-CREB signaling [#24, #30, #38]. Gain-of-function mutations elevate persistent and/or resurgent currents to cause neuronal hyperexcitability and epileptic encephalopathy, acting critically through excitatory neurons but also via depolarization block and inhibitory failure of SST and PV interneurons, while loss-of-function variants reduce firing; this disease link is established by knock-in mouse models, patient iPSC neurons, and antisense rescue [#17, #28, #29, #35, #36, #39, #31].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established that SCN8A encodes a neuron-specific sodium channel whose loss is lethal, defining its identity and the consequence of deficiency.\",\n      \"evidence\": \"Positional cloning and transgene-induced deletion with tissue expression analysis in mice\",\n      \"pmids\": [\"7670495\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define subcellular localization or biophysical properties\", \"Mechanism linking channel loss to Purkinje degeneration unresolved\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Resolved where Nav1.6 acts by localizing it to nodes of Ranvier, axon initial segments, and dendrites, linking the channel to action potential initiation and propagation.\",\n      \"evidence\": \"Isoform-specific immunohistochemistry in rat nervous system\",\n      \"pmids\": [\"10745220\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Localization mechanism not addressed\", \"Functional consequence of dendritic localization untested\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Provided the biophysical basis for Nav1.6-driven high-frequency firing through fast repriming and identified calmodulin as a direct C-terminal regulator of current and inactivation.\",\n      \"evidence\": \"Whole-cell patch clamp of recombinant channels in DRG neurons; GST pulldown, co-expression, and C-terminal mutagenesis\",\n      \"pmids\": [\"12843211\", \"12967988\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Calmodulin's structural binding mode not defined\", \"In vivo relevance of CaM modulation not tested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Explained why Nav1.6 sustains rather than dampens repetitive firing by demonstrating use-dependent potentiation arising from fast activation and slow-inactivation resistance.\",\n      \"evidence\": \"Patch clamp of Nav1.6 vs Nav1.2 with fast-inactivation-removed mutants in Xenopus oocytes\",\n      \"pmids\": [\"15465873\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Native neuron relevance addressed only later\", \"Molecular determinants of slow-inactivation resistance not mapped\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Opened post-translational regulation of Nav1.6 by identifying p38 MAPK phosphorylation at Ser553 that suppresses current without altering gating.\",\n      \"evidence\": \"In vitro kinase assay, S553A mutagenesis, patch clamp in p38-activated cells\",\n      \"pmids\": [\"16014723\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological trigger of p38 regulation unclear\", \"Whether reduction reflects trafficking or open probability not resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated in vivo that Nav1.6 is required for sustained high-frequency firing and that other isoforms partially compensate at AIS and nodes.\",\n      \"evidence\": \"Patch clamp and immunofluorescence in retinal ganglion cells from null vs wild-type mice\",\n      \"pmids\": [\"16822974\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Compensation mechanism not defined\", \"Persistent vs resurgent contributions not separated here\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Attributed resurgent sodium current and pacemaking/fast-spiking to Nav1.6, defining its role in autonomous firing.\",\n      \"evidence\": \"Patch clamp in null GPe neurons plus computational modeling\",\n      \"pmids\": [\"18057213\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of resurgent current not addressed\", \"Beta4/FHF dependency identified only later\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Linked activity-dependent increases in Nav1.6 and persistent current to seizure circuit facilitation, an early connection to epileptogenesis.\",\n      \"evidence\": \"Immunocytochemistry, in situ hybridization, patch clamp and kindling in wild-type vs Nav1.6+/- mice\",\n      \"pmids\": [\"18637833\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether persistent current increase is cause or consequence of hyperactivity not separated\", \"Cell-type specificity not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified FGF14 splice variants and Nav1.6 mechanosensitivity, showing the channel is both a regulated complex member and a mechanically gated sodium leak.\",\n      \"evidence\": \"Co-expression patch clamp with FGF14 deletion mutants; mechanical stretch/aspiration with Na+ dye fluorimetry in heterologous cells\",\n      \"pmids\": [\"19465131\", \"19657055\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanotransduction structural mechanism unknown\", \"In vivo significance of mechanosensitivity untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Refined Nav1.6's firing role to persistent-current-dependent temporal precision and established beta1 as required for AIS localization and resurgent current.\",\n      \"evidence\": \"Conditional KO granule cell patch clamp; Scn1b-null AIS immunofluorescence, electrophysiology, and shRNA knockdown\",\n      \"pmids\": [\"20173079\", \"20133873\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Beta1 targeting mechanism not molecularly defined\", \"Interplay of beta1 with other trafficking partners unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Clarified beta-subunit modulation as comparatively weak for Nav1.6, distinguishing its regulation from other isoforms.\",\n      \"evidence\": \"Co-expression of beta1-beta4 and beta-subunit chimeras in Xenopus oocytes with patch clamp\",\n      \"pmids\": [\"21562192\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single heterologous system\", \"Beta4 role in resurgent current not addressed here\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified Map1b as an N-terminal trafficking partner essential for Nav1.6 surface current, mechanistically linking channel delivery to the cytoskeleton.\",\n      \"evidence\": \"Yeast two-hybrid, brain co-IP, alanine-scanning mutagenesis (residues 77-80), patch clamp\",\n      \"pmids\": [\"22474336\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Step in trafficking pathway affected not defined\", \"Whether Map1b acts with beta1 or independently unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated a causal role for Nav1.6 in peripheral pathological pain and ectopic bursting following inflammation.\",\n      \"evidence\": \"In vivo DRG siRNA knockdown with behavioral, single-unit, qPCR and IHC readouts in rat\",\n      \"pmids\": [\"23622763\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether effect is via persistent or resurgent current not separated\", \"Upstream inflammatory regulation defined only later\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Established gain-of-function as the disease mechanism in SCN8A epileptic encephalopathy via persistent-current and activation-shift mutations.\",\n      \"evidence\": \"N1768D knock-in mouse with EEG and dose-response; T767I mutagenesis with patch clamp in cells and neurons\",\n      \"pmids\": [\"25227913\", \"24874546\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Critical cell type not yet identified\", \"Connection from channel biophysics to network seizures not resolved here\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Expanded the trafficking and signaling network controlling Nav1.6 by identifying APP-Go-JNK surface regulation, kinase control of the FGF14:Nav1.6 complex, and a peripheral spike-initiation role.\",\n      \"evidence\": \"Reciprocal co-IP, Go/JNK mutants and T668 mutagenesis with biotinylation; split-luciferase kinase screen with neuronal electrophysiology; selective Nav1.6 toxins in colon-nerve preparation\",\n      \"pmids\": [\"25767117\", \"25659151\", \"25652923\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"GSK3/PI3K regulation acts indirectly through FGF14\", \"In vivo significance of APP-Nav1.6 axis not tested at this stage\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connected gain-of-function mutations to elevated resurgent current, identified CDYL-H3K27me3 transcriptional repression, FHF2 isoform regulation of resurgent current, somatic nanocluster organization, and a pharmacological handle (cannabidiol).\",\n      \"evidence\": \"Mutant channel patch clamp with Navbeta4 peptide; ChIP and in vivo CDYL gain/loss-of-function; FHF2 chimeras and siRNA in DRG neurons; single-particle tracking/PALM imaging; M136V electrophysiology\",\n      \"pmids\": [\"27267376\", \"28842554\", \"27999940\", \"27653482\", \"27496104\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Nanocluster scaffolding identity beyond ankyrin-independence unknown\", \"Resurgent current's molecular partner in vivo not fully defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Localized seizure mechanisms to specific neuron types, showing both excitatory persistent-current elevation (with reverse NCX) and reticular thalamic inhibitory failure can drive distinct seizure phenotypes.\",\n      \"evidence\": \"N1768D knock-in cell-type patch clamp with TTX/riluzole/SN-6 pharmacology; conditional RT-cell and adult thalamic KO with EEG\",\n      \"pmids\": [\"28193882\", \"28238546\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of excitatory vs inhibitory mechanisms to overall disease not weighed here\", \"Reverse NCX role inferred pharmacologically\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Pinpointed excitatory neurons as the critical pathogenic cell type for gain-of-function encephalopathy, distinguished gain- from loss-of-function and depolarization-block variants, and showed Nav1.6 promotes neuroinflammation after demyelination.\",\n      \"evidence\": \"Cell-type-specific Cre knock-in with EEG/survival; multi-variant patch clamp with computational modeling; AAV-Cre conditional deletion in EAE\",\n      \"pmids\": [\"30601941\", \"30615093\", \"31722722\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Inhibitory neuron contributions revisited in later work\", \"EAE neuroinflammation mechanism is correlative/conditional, single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Mapped the post-translational control surface of Nav1.6 (CaMKII, S-palmitoylation, JAK2-FGF14) and demonstrated therapeutic transcript reduction by antisense oligonucleotides in two epilepsy models.\",\n      \"evidence\": \"Mass spectrometry, mutagenesis and patch clamp for CaMKII sites; acyl-biotin exchange and mutagenesis for palmitoylation; HTS, MS and FGF14Y158A patch clamp for JAK2; ICV ASO in R1872W and Scn1a+/- mice; patient iPSC neuron electrophysiology\",\n      \"pmids\": [\"32611770\", \"32161114\", \"32599005\", \"31943325\", \"32968789\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Integration of competing PTMs on the same channel pool not resolved\", \"ASO long-term safety and cognitive effects not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Demonstrated that gain-of-function in SST inhibitory interneurons paradoxically promotes seizures through depolarization block driven by persistent current.\",\n      \"evidence\": \"SST-Cre conditional knock-in with EEG, patch clamp, pharmacology, modeling and chemogenetics\",\n      \"pmids\": [\"34544834\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative weight of SST vs excitatory contributions in patients unclear\", \"Mechanism of selective audiogenic susceptibility unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Linked Nav1.6 to Alzheimer's pathology by showing hippocampal knockdown rescues cognition and lowers amyloid via a reverse-NCX/calcium/NFAT1/BACE1 axis.\",\n      \"evidence\": \"AAV-shRNA knockdown in APP/PS1 mice with behavioral, biochemical and calcium imaging readouts\",\n      \"pmids\": [\"35353937\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NFAT1-BACE1 pathway partially inferred, single lab\", \"Direct demonstration of reverse NCX in vivo limited\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified MAPK-ERK-CREB transcriptional induction of Nav1.6 as a driver of chemotherapy-induced neuropathic pain.\",\n      \"evidence\": \"ChIP for CREB at Scn8a promoter, kinase inhibitor pharmacology, qPCR and behavior in rats\",\n      \"pmids\": [\"37453670\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single pain model\", \"Crosstalk with other Scn8a transcriptional regulators not examined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed that PV interneuron gain-of-function alone causes spontaneous lethal seizures and that splice-isoform and TTX-resistance context shape variant phenotypes, refining genotype-phenotype interpretation.\",\n      \"evidence\": \"PV-Cre conditional knock-in with EEG and synaptic/intrinsic electrophysiology; automated patch clamp of 15 variants across two isoforms in engineered low-Nav cells\",\n      \"pmids\": [\"39435659\", \"38771640\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Combined effect of excitatory and multiple interneuron classes in patients not modeled\", \"Physiological role of neonatal vs adult isoform switch not defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the many parallel regulatory inputs (phosphorylation, palmitoylation, accessory subunits, trafficking partners, and transcriptional/epigenetic control) are coordinated on a single Nav1.6 channel pool to set excitability in specific neuron types remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No integrated model of competing PTMs and partners on the same channel\", \"Structural basis of resurgent current and nanocluster scaffolding undefined\", \"Cell-type-specific therapeutic targeting not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 2, 5, 8, 11, 12]},\n      {\"term_id\": \"GO:0005216\", \"supporting_discovery_ids\": [0, 2, 8]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 11, 19, 25]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [1, 15]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [2, 7, 8, 12]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [17, 28, 29, 35, 36, 39]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [14, 24, 30, 38]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CALM\", \"FGF14\", \"MAP1B\", \"SCN1B\", \"APP\", \"SCN4B\", \"FHF2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}