{"gene":"RYR2","run_date":"2026-06-10T07:46:28","timeline":{"discoveries":[{"year":2001,"finding":"RYR2 mutations (in N-terminal, central, and C-terminal regions) cause ARVD2/CPVT; RyR2 encodes the cardiac sarcoplasmic reticulum Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling.","method":"Genomic structure elucidation, mutation identification by sequencing in affected families, cosegregation analysis","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — independently replicated across two papers (PMID:11159936 and PMID:11157710), cosegregation demonstrated in multiple independent families","pmids":["11159936","11157710"],"is_preprint":false},{"year":2005,"finding":"Disease-linked RyR2 mutations (from N-terminal, central, and C-terminal regions) enhance the sensitivity of the channel to luminal (but not cytosolic) Ca2+ activation and increase the propensity for store overload-induced Ca2+ release (SOICR); no alteration in FKBP12.6-RyR2 interaction was detected.","method":"Stable inducible HEK293 cell lines expressing mutant RyR2, single-channel analysis, [3H]ryanodine binding, single-cell Ca2+ imaging in HL-1 cardiac cells","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (single-channel recordings, ryanodine binding, cellular Ca2+ imaging) across 6 mutations in two cell types","pmids":["16239587"],"is_preprint":false},{"year":2002,"finding":"VTSIP-associated RyR2 point mutations increase, while ARVD2-associated mutations decrease, binding of RyR2 to its gating protein FKBP12.6, as measured by quantitative yeast two-hybrid assay.","method":"Quantitative yeast two-hybrid assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single method (yeast two-hybrid), but multiple mutations tested with consistent directional effects","pmids":["12459180"],"is_preprint":false},{"year":2010,"finding":"In the mdx mouse model of Duchenne muscular dystrophy, RyR2 is S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in leaky RyR2 channels and diastolic SR Ca2+ leak that triggers cardiac arrhythmias; stabilizing the RyR2-calstabin2 complex with S107 inhibited SR Ca2+ leak and prevented arrhythmias in vivo.","method":"Co-immunoprecipitation, S-nitrosylation assay, confocal Ca2+ imaging, in vivo arrhythmia monitoring in mdx mice","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (biochemistry, imaging, in vivo pharmacology) with clear mechanistic rescue","pmids":["20080623"],"is_preprint":false},{"year":2012,"finding":"CaMKII phosphorylation of RyR2 at S2814 (but not PKA phosphorylation at S2808) is increased in non-ischemic heart failure; knock-in mice with inactivated S2814 (S2814A) are protected from pressure-overload heart failure and exhibit reduced SR Ca2+ leak.","method":"Knock-in mouse model (S2814A), transverse aortic constriction, confocal Ca2+ imaging, Western blotting","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knock-in with defined phosphorylation site, multiple phenotypic readouts, confirmed in human non-ischemic HF tissue","pmids":["22511749"],"is_preprint":false},{"year":2011,"finding":"CaMKII phosphorylation of RyR2 at S2814 (not S2808) is required for SR Ca2+ leak, delayed afterdepolarizations (DADs), and atrial fibrillation induction in FKBP12.6-knockout mice; genetic inhibition of S2814 phosphorylation (S2814A knock-in) reduces Ca2+ spark frequency and prevents AF.","method":"Double knock-in mouse models (FKBP12.6-/-:S2814A and FKBP12.6-/-:S2808A), confocal Ca2+ imaging, patch clamp, intracardiac pacing","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with two distinct phospho-site knock-ins, multiple functional readouts","pmids":["22158709"],"is_preprint":false},{"year":2003,"finding":"CaM inhibits RyR2 at all Ca2+ concentrations (100 nM–1 mM), increasing the Ca2+ EC50 of RyR2 7–10-fold; C-terminal Ca2+-binding sites on CaM determine the inhibitory effect, and apoCaM (Ca2+-binding deficient mutant) activates RyR2 and acts as a competitive inhibitor of Ca2+CaM regulation.","method":"Biochemical assay of RyR2 activity with Ca2+-insensitive CaM mutants, [3H]ryanodine binding","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with panel of CaM mutants, multiple binding/activity measurements","pmids":["12614169"],"is_preprint":false},{"year":2013,"finding":"In situ, CaM binds RyR2 with high affinity (Kd ~10–20 nM); >90% of Z-line CaM in cardiomyocytes is RyR2-bound; reduced CaM-RyR2 affinity (~3-fold increase in Kd) occurs in post-MI rat heart failure; reduced CaM binding in RyR2(ADA/+) knock-in mice increases Ca2+ wave production and stress-induced ventricular arrhythmia.","method":"FRET in permeabilized cardiomyocytes, RyR2(ADA/+) knock-in mouse model, post-MI rat heart failure model","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (FRET, genetic knock-in, disease model) with functional consequence","pmids":["24186966"],"is_preprint":false},{"year":2016,"finding":"CaMKII phosphorylation of RyR2 at S2814 promotes a pathological RyR2 conformational state (increased DPc10 access, reduced CaM affinity, elevated Ca2+ leak); dantrolene restores CaM affinity, reduces DPc10 access, and suppresses SR Ca2+ leak and ventricular tachycardia in RyR2-S2814D mice.","method":"Phosphomimetic/phosphoablative knock-in mice (S2814D/S2814A), DPc10 peptide conformational assay, FRET-based CaM affinity measurement, confocal Ca2+ imaging, in vivo arrhythmia assessment","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods with genetic and pharmacological interventions validating the same mechanistic pathway","pmids":["27318036"],"is_preprint":false},{"year":2015,"finding":"CaMKIIδ-dependent phosphorylation of RyR2-S2814 mediates SR Ca2+ leak in response to β-adrenergic stimulation; CaMKIIδ-KO and S2814A knock-in mice are protected from cardiomyopathy induced by chronic isoproterenol, without blocking hypertrophy.","method":"CaMKIIδ-KO and S2814A knock-in mice, Langendorff heart perfusion, confocal Ca2+ imaging, chronic isoproterenol treatment","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — two independent genetic models with consistent phenotype, multiple functional readouts","pmids":["26080362"],"is_preprint":false},{"year":2019,"finding":"CaM binds to four CaM-binding domains (CaMBD1a, -1b, -2, -3) in RyR2 in a Ca2+-dependent manner; the CaM C-domain anchors to CaMBD2 (essentially Ca2+-saturated at rest), while the CaM N-domain dynamically senses Ca2+ in the physiological range when complexed with CaMBD2 or CaMBD3.","method":"Fluorescence anisotropy with TAMRA-labeled CaMBD peptides, Ca2+ titrations, isolated CaM domain binding experiments","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with multiple CaM domains, quantitative binding measurements across Ca2+ concentrations","pmids":["30530841"],"is_preprint":false},{"year":2019,"finding":"Phosphorylation of human RyR2 at S2808 or S2814 is necessary and sufficient for CaM inhibitory activity on RyR2; CaM (100 nM) inhibits RyR2 from failing human hearts (~50%) but has no effect on RyR2 from healthy human hearts, a difference attributable to phosphorylation state.","method":"Artificial lipid bilayer single-channel recording, FRET (donor-FKBP12.6/acceptor-CaM), Ca2+ spark measurements in phosphomimetic/phosphoablated RyR2 knock-in cardiomyocytes","journal":"Journal of molecular and cellular cardiology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — single-channel electrophysiology, FRET, and genetic knock-in models in multiple species","pmids":["30928430"],"is_preprint":false},{"year":2020,"finding":"Ca2+-CaM dependent inactivation of RyR2 is a major determinant of Ca2+ alternans; CaM gain-of-function (CaM-M37Q) promotes and CaM loss-of-function (CaM-1-4) suppresses Ca2+ alternans in intact working mouse hearts; PKA phosphorylation of RyR2 at S2030 modulates CaM-dependent inactivation and Ca2+ alternans.","method":"In vivo adenoviral delivery of CaM variants into mouse myocardium, confocal Ca2+ imaging in Langendorff-perfused hearts, numerical modeling","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct in vivo manipulation of CaM function with gain/loss-of-function variants, validated by numerical model across 9 experimental conditions","pmids":["33375811"],"is_preprint":false},{"year":2022,"finding":"PKA phosphorylation of RyR2 at S2030 governs Ca2+ release termination threshold via CaM-dependent inactivation; S2030L mutation abolishes CaM-wild-type and PKA effects on termination but preserves CaMKII effects, placing S2030 within the CaM-dependent inactivation pathway.","method":"ER Ca2+ imaging in HEK293 cells, S2030L knock-in mouse model, confocal Ca2+ imaging, pharmacological CaMKII/PKA inhibition","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knock-in mouse combined with HEK293 functional studies and pharmacological dissection of PKA vs CaMKII pathways","pmids":["36583384"],"is_preprint":false},{"year":2020,"finding":"RyR2 channel inhibition (not solely sodium channel block) is the principal mechanism of flecainide's antiarrhythmic action in CPVT; N-methylated flecainide analogues that lose RyR2 inhibitory potency (while retaining sodium channel block) fail to suppress CPVT arrhythmias in Casq2-/- mice.","method":"Synthesis of N-methylated flecainide analogues, lipid bilayer RyR2 single-channel recordings, HEK293 sodium channel assays, membrane-permeabilized and voltage-clamped Casq2-/- cardiomyocytes, in vivo catecholamine challenge","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — chemical biology approach with matched analogues, multiple orthogonal assays, in vitro and in vivo validation","pmids":["33297863"],"is_preprint":false},{"year":2013,"finding":"The CPVT-associated RyR2 G230C N-terminal mutation enhances SOICR propensity by sensitizing the channel to both luminal and cytosolic Ca2+ activation, and decreases thermal stability of the N-terminal domain (residues 1–547) of RyR2.","method":"Stable inducible HEK293 cell lines, single-cell Ca2+ imaging (SOICR assay), single-channel recordings, [3H]ryanodine binding, thermal stability assay of recombinant N-terminal fragment","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal methods including structural stability assay and single-channel recordings","pmids":["23746327"],"is_preprint":false},{"year":2015,"finding":"RyR2 in pancreatic β cells regulates insulin secretion and glucose homeostasis; leaky RyR2 channels (via oxidation and S-nitrosylation) cause ER stress, mitochondrial dysfunction, and decreased insulin release in CPVT mice and diabetic human islets.","method":"Transgenic CPVT RyR2 mice, islet isolation and Ca2+ imaging, ER stress assays, mitochondrial function assays, pharmacological Ca2+ leak inhibition","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal mechanistic assays in transgenic mice and human islets with pharmacological rescue","pmids":["25844899"],"is_preprint":false},{"year":2004,"finding":"Inhibiting RyR2 in pancreatic β cells markedly increases apoptosis via a caspase-3-independent, calpain-10-dependent death pathway; RyR2 activity suppresses calpain-10-mediated apoptosis in β cells.","method":"Pharmacological inhibition (ryanodine), pharmacological and genetic inhibition of calpain-10 in human and mouse β cells, apoptosis assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — pharmacological and genetic approaches in human and murine cells, multiple orthogonal functional assays","pmids":["15044459"],"is_preprint":false},{"year":2016,"finding":"RyR2 Ca2+ release in cardiomyocytes specifically promotes mitochondrial Ca2+ uptake and glucose oxidation via pyruvate dehydrogenase activation; 50% reduction in Ryr2 protein (haploinsufficiency) decreases mitochondrial Ca2+ signals and impairs glucose oxidation without affecting cardiac contraction.","method":"Inducible heart-specific Ryr2 haploinsufficient mice (cRyr2Δ50), confocal Ca2+ imaging, metabolic flux analysis, metabolomics, proteomics, transcriptomics","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic model with multiple orthogonal metabolic and Ca2+ imaging assays establishing specific metabolic pathway","pmids":["27621312"],"is_preprint":false},{"year":2022,"finding":"ERp44 associates with RyR2 via intraluminal cysteine 4806 in a redox-sensitive manner; Ero1α-mediated SR oxidation causes ERp44 dissociation from the RyR2 complex, increasing RyR2 Ca2+ channel activity and promoting proarrhythmic spontaneous Ca2+ release.","method":"Co-immunoprecipitation, site-directed mutagenesis (C4806), molecular dynamics simulation, genetic Ero1α overexpression/knockdown, intra-SR ROS biosensor (ERroGFP), pharmacological inhibition (EN460), rat TAB model","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — mutagenesis of interaction site, molecular dynamics, multiple orthogonal biochemical and functional approaches","pmids":["35086342"],"is_preprint":false},{"year":2019,"finding":"Junctophilin proteins (JPH3/JPH4) tether a Cav1.3-RyR2-KCa3.1 tripartite complex at the plasma membrane-ER junction in hippocampal CA1 neurons; disruption of this complex (by JPH3/4 shRNA or antibody infusion) dissociates Cav1.3-RyR2-KCa3.1 and reduces the slow AHP current.","method":"dSTORM super-resolution microscopy, FRET microscopy, shRNA knockdown, antibody infusion, patch clamp electrophysiology in CA1 neurons","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — super-resolution imaging and FRET confirm complex proximity, genetic and antibody disruption with electrophysiological functional readout","pmids":["31461656"],"is_preprint":false},{"year":2021,"finding":"RyR2 physically interacts with Cx43 (<40 nm proximity by PLA); RyR activation and intracellular Ca2+ elevation together are necessary to open Cx43 hemichannels at diastolic membrane potential; a RyR-mimicking peptide (RyRHCIp) inhibits RyR/Ca2+-triggered HC activation.","method":"Proximity ligation assay, co-immunoprecipitation, whole-cell patch clamp, molecular modelling, Ca2+ clamp experiments","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP + PLA confirming physical interaction, functional demonstration with Ca2+-clamp and peptide inhibitor","pmids":["31841141"],"is_preprint":false},{"year":2020,"finding":"Augmented RyR2 activity (pharmacological or genetic CPVT mutation) increases mitochondrial ROS emission via altered SR-mitochondrial Ca2+ transfer; mito-ROS in turn oxidizes RyR2, further amplifying proarrhythmic SR Ca2+ release in a positive feedback cycle (leak begets leak); dominant-negative MCU abrogates this effect.","method":"Spatially restricted genetic ROS probes, mitochondrial Ca2+ probe (mtRCamp1h), dominant-negative MCU expression, CPVT mouse ventricular myocytes, pharmacological ROS scavenging","journal":"Basic research in cardiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic ROS probes, dominant-negative genetic tool, multiple orthogonal readouts establishing the feedback mechanism","pmids":["32444920"],"is_preprint":false},{"year":2020,"finding":"A single RyR2 point mutation E4872Q that reduces RyR2 open time prevents neuronal hyperexcitability, memory impairment, dendritic spine loss, and neuronal cell death in 5xFAD Alzheimer's disease mice; the mechanism involves upregulation of hippocampal CA1 A-type K+ current.","method":"RyR2-E4872Q knock-in mouse crossed with 5xFAD, behavioral tests, patch clamp (A-type K+ current), pharmacological treatment (R-carvedilol)","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knock-in with defined channel property change, pharmacological validation, specific electrophysiological mechanism identified","pmids":["32966798"],"is_preprint":false},{"year":2016,"finding":"The leaky RyR2-R176Q gain-of-function mutation in neurons selectively strengthens excitatory (but not inhibitory) synapses and lowers the threshold for spreading depolarization in the dorsal medulla, leading to cardiorespiratory collapse; this links neuronal RyR2 Ca2+ dysregulation to brainstem spreading depolarization as a mechanism of sudden death.","method":"RyR2-R176Q knock-in mouse model (RQ/+), in vitro electrophysiology (excitatory/inhibitory synapse recordings), spreading depolarization assay, in vivo EEG/ECG monitoring","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic knock-in with mechanistic in vitro and in vivo electrophysiology establishing synapse-specific effect","pmids":["27482086"],"is_preprint":false},{"year":2016,"finding":"A RyR2 loss-of-function mutation (I4855M) in the inner vestibule of the pore inhibits caffeine-induced Ca2+ release and exerts a dominant-negative effect on wild-type RyR2 when co-expressed in HEK293 cells.","method":"HEK293 cell Ca2+ release assay, homology modelling of RyR2 pore region, co-expression studies","journal":"Journal of electrocardiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional cell assay and co-expression dominant-negative study, structural model is in silico only","pmids":["27646203"],"is_preprint":false},{"year":2021,"finding":"Two additional RyR2 loss-of-function mutations (E4146K and G4935R) markedly suppress cytosolic and luminal Ca2+ activation of single RyR2 channels; G4935R exerts a dominant-negative effect on wild-type RyR2; these LOF mutations are associated with a distinct arrhythmia syndrome (CRDS) different from CPVT.","method":"HEK293 cell SOICR assay, [3H]ryanodine binding, single-channel recordings in lipid bilayers, co-expression dominant-negative studies","journal":"Bioscience reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro single-channel electrophysiology with multiple assays (ryanodine binding, SOICR, co-expression) for two distinct mutations","pmids":["33825858"],"is_preprint":false},{"year":2020,"finding":"Integrin β1D protein directly stabilizes RyR2 function by decreasing RyR2 open probability, mean open time, and increasing mean close time (lipid bilayer patch clamp); loss of integrin β1D in ARVC leads to RyR2-S2030 hyperphosphorylation and aberrant Ca2+ handling causing catecholamine-sensitive polymorphic ventricular tachycardia.","method":"Purified integrin β1D protein + lipid bilayer patch clamp single-channel recordings, cardiac-specific β1D KO mouse model, Western blotting, confocal Ca2+ imaging","journal":"Circulation","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct reconstitution of integrin β1D effect on RyR2 channels in bilayers plus genetic KO mouse with functional phenotype","pmids":["32122157"],"is_preprint":false},{"year":2014,"finding":"Doxorubicin and its metabolite doxorubicinol bind to and activate single RyR2 channels, then cause irreversible inhibition via thiol oxidation (reducing thiol groups on RyR2); both effects are reversed/prevented by the reducing agent DTT, identifying oxidation of RyR2 cysteines as the mechanism of secondary inhibition.","method":"Single RyR2 channel recordings, thiol group quantification, SR vesicle Ca2+ uptake assay, drug washout experiments","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro single-channel electrophysiology with mechanistic dissection using reducing agent and washout","pmids":["25106424"],"is_preprint":false},{"year":2019,"finding":"All 14 arrhythmogenic CaM mutations tested diminish CaM-dependent inhibition of RyR2-mediated Ca2+ release and increase SOICR; many CaM mutations fail to inhibit or even facilitate RyR2-mediated Ca2+ release at elevated cytosolic Ca2+, and alter Ca2+-dependency of CaM binding to the RyR2 CaM-binding domain.","method":"HEK293 cells expressing RyR2 with arrhythmogenic CaM mutations, SOICR Ca2+ imaging, permeabilized cell Ca2+ release assay, CaM-binding domain interaction studies","journal":"The FEBS journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — systematic study of 14 mutations with multiple orthogonal Ca2+ release assays","pmids":["31230402"],"is_preprint":false},{"year":2014,"finding":"Human RyR2 displays cytoplasmic Ca2+ activation (Ka ~4 µM) inhibited by cytoplasmic Mg2+ (Ki ~10 µM); luminal Ca2+ activation (Ka ~35 µM) is similar to sheep but distinct from rat; physiological Mg2+ (1 mM) raises Ka for cytoplasmic Ca2+ to ~30 µM in human and sheep RyR2.","method":"Artificial lipid bilayer single-channel recordings of native RyR2 from healthy and failing human, sheep, and rat hearts","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro single-channel electrophysiology comparing three species with systematic ion concentration variation","pmids":["25156119"],"is_preprint":false},{"year":2014,"finding":"RyR2-mediated Ca2+ release is necessary and sufficient for activation of SK2 (small-conductance Ca2+-activated K+) channels in atrial cardiomyocytes; SK2 and RyR2 co-immunoprecipitate from native cardiac tissue, indicating a physical interaction.","method":"Whole-cell patch clamp, co-immunoprecipitation, lentiviral shRNA knockdown of RyR2, pharmacological RyR2 activation/inhibition, confocal Ca2+ imaging","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP combined with functional patch-clamp and genetic knockdown, single lab","pmids":["24747296"],"is_preprint":false},{"year":2022,"finding":"Cytosolic Ca2+-dependent activity of RyR2 at resting Ca2+ (Arest) is the primary determinant of the ER luminal Ca2+ threshold for spontaneous Ca2+ release; CPVT mutations increase Arest and lower the threshold [Ca2+]ER in a manner that correlates with age of disease onset in patients.","method":"HEK293 cell expression of WT and CPVT-mutant RYR2, fluorescent Ca2+ indicators for cytosolic and ER Ca2+, in silico modeling","journal":"The Journal of general physiology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic in vitro characterization across multiple mutations with quantitative kinetic modeling","pmids":["35446340"],"is_preprint":false},{"year":2023,"finding":"RyR2 depletion in cardiomyocytes activates ER stress pathways (including ATF4 upregulation) that perturb cardiomyocyte maturation; tauroursodeoxycholic acid (ER stress alleviator) partially rescues these defects; ATF4 overexpression recapitulates RyR2-depletion phenotype, with protein biosynthesis genes as major ATF4 targets.","method":"Cas9/AAV9 somatic RYR2 knockout in cardiomyocytes, genetic mosaic analysis, RNA-Seq, bioChIP-Seq, tauroursodeoxycholic acid treatment, ATF4 overexpression","journal":"Cardiovascular research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple orthogonal genomic and functional methods establishing ER stress as mechanistic intermediary","pmids":["35576474"],"is_preprint":false},{"year":2021,"finding":"RyR2-mediated Ca2+ release in hippocampal neurons contributes to nuclear Ca2+ signals generated by neuronal activity; RyR-mediated Ca2+ release is required for CREB phosphorylation, Npas4 expression, and RyR2 upregulation in response to gabazine or high-frequency stimulation.","method":"Confocal Ca2+ imaging in primary hippocampal neurons, pharmacological RyR inhibition with ryanodine, glutamate uncaging, high-frequency field stimulation, Western blot","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live Ca2+ imaging with pharmacological inhibition showing RyR2-dependent signal transduction to nucleus","pmids":["34389673"],"is_preprint":false},{"year":2023,"finding":"RyR2 loss-of-function mutation I4855M increases Ca2+-induced Ca2+ release gain, abolishes SOICR, elevates SR Ca2+ load, prolongs Ca2+ transient decay, and elevates end-diastolic Ca2+ upon rapid pacing, providing a mechanism for CRDS-associated LVNC.","method":"I4855M knock-in mouse model, echocardiography, confocal Ca2+ imaging, immunoblotting, histological analysis","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knock-in mouse recapitulating human LVNC phenotype, multiple orthogonal Ca2+ handling measurements","pmids":["37325910"],"is_preprint":false},{"year":2020,"finding":"In ARVC hearts, integrin β1D deficiency leads to RyR2-S2030 hyperphosphorylation through a DSP-loss → ERK1/2-fibronectin-ubiquitin/lysosome pathway, causing RyR2 dysfunction and catecholamine-sensitive ventricular tachycardia.","method":"Protein mass spectrometry of ARVC hearts, cardiac-specific β1D KO mouse, Western blotting, confocal Ca2+ imaging","journal":"Circulation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic pathway established in KO mouse model with human tissue correlation, single lab","pmids":["32122157"],"is_preprint":false},{"year":2019,"finding":"KN93, widely used as a CaMKII inhibitor, directly binds CaM and disrupts high-affinity CaM-NaV1.5 interaction and alters NaV1.5 channel function; KN93 also increases RyR2 Ca2+ release in cardiomyocytes independently of CaMKII, by interfering with CaM binding to RyR2.","method":"X-ray crystallography (CaM-KN93 structure), NMR spectroscopy, stopped-flow kinetics, NaV1.5 functional assay, confocal Ca2+ imaging in cardiomyocytes","journal":"Cell calcium","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure combined with biophysical and functional assays establishing CaM-mediated off-target mechanism","pmids":["31401388"],"is_preprint":false},{"year":2020,"finding":"CD38 expression on CD8+ T cells elevates intracellular Ca2+ through RyR2 Ca2+ channel activation, promoting chronic AKT activation and TCF1 loss leading to terminal CD8+ T cell exhaustion; RyR2 knockdown in CD8+ T cells maintains TCF1 levels and improves anti-tumor responses and responsiveness to anti-PD1 therapy.","method":"Genetic ablation of CD38, RyR2 knockdown in CD8+ T cells, Ca2+ imaging, AKT inhibition, single-cell RNA sequencing, in vivo tumor models","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockdown with multiple functional readouts in T cells, single lab; ortholog of canonical cardiac channel in immunological context","pmids":["38451948"],"is_preprint":false},{"year":2022,"finding":"RyR2 deletion from INS-1 β cells (RyR2KO) reduces IRBIT protein levels, increases IP3R activity, reduces insulin content, impairs insulin secretion, reduces INS1 and INS2 mRNA, and increases nuclear AHCY with increased exonic DNA methylation; RyR2 and IRBIT co-regulate insulin gene expression and secretion.","method":"CRISPR knockout of RyR2 in INS-1 cells, IRBIT KO, insulin secretion assays, RT-PCR, DNA methylation analysis, exploratory proteomics","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with multiple functional readouts; mechanism of IRBIT regulation is correlative rather than directly reconstituted","pmids":["35562179"],"is_preprint":false},{"year":2018,"finding":"RyR2-P2328S mutation from arrhythmic RyR2S/S mice shifts Ca2+ activation 10-fold (AC50 from ~3.5 µM to ~320 nM) and dramatically shifts Ca2+ inactivation threshold >1000-fold (IC50 from ~50 mM to ≤7 µM, within systolic Ca2+ range), without changes in phosphorylation or FKBP12 binding.","method":"Artificial lipid bilayer single-channel recordings from RyR2S/S mouse hearts, Western blotting for phosphorylation and FKBP binding","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro single-channel electrophysiology with quantitative Ca2+ dose-response, biochemical controls","pmids":["31028179"],"is_preprint":false},{"year":2022,"finding":"RyR2 clusters in the periphery of live ventricular myocytes show irregular distribution and dynamic movement (detected by GFP-tagged RyR2 knock-in), unlike the ordered arrays in the interior; peripheral cluster movement is modulated by external Ca2+ and RyR2 activators/inhibitors, and peripheral clusters generate Ca2+ release similar to interior clusters.","method":"GFP-RyR2 knock-in mouse model, confocal imaging, TIRF microscopy, simultaneous Ca2+/GFP imaging in live ventricular myocytes and intact hearts","journal":"Biophysical journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — live imaging with genetically tagged channel demonstrating dynamic subcellular localization with functional correlate","pmids":["29401432"],"is_preprint":false}],"current_model":"RyR2 is the tetrameric cardiac sarcoplasmic reticulum Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling; it is regulated by luminal and cytosolic Ca2+, Mg2+, calmodulin (which inhibits RyR2 at all Ca2+ concentrations and whose binding is modulated by phosphorylation state), FKBP12.6 (calstabin2), and post-translational modifications including CaMKII phosphorylation at S2814 (promoting leak and arrhythmia), PKA phosphorylation at S2030 (modulating CaM-dependent inactivation and Ca2+ alternans), S-nitrosylation, and redox oxidation; gain-of-function mutations enhance luminal Ca2+ sensitivity and SOICR causing CPVT/ARVD2, while loss-of-function mutations reduce Ca2+ release causing CRDS; beyond the heart, RyR2 operates in pancreatic β cells (regulating insulin secretion via IRBIT), hippocampal neurons (mediating nuclear Ca2+ signals for CREB phosphorylation and synaptic plasticity), and T cells (activating Ca2+-AKT signaling)."},"narrative":{"mechanistic_narrative":"RYR2 encodes the tetrameric cardiac sarcoplasmic reticulum (SR) Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling, and gain- and loss-of-function mutations distributed across its N-terminal, central, and C-terminal regions cause the inherited arrhythmias ARVD2/CPVT and CRDS [PMID:11159936, PMID:11157710, PMID:33825858]. The channel is gated by cytosolic Ca2+ activation and Mg2+ inhibition together with luminal Ca2+, and its resting cytosolic Ca2+ sensitivity sets the luminal Ca2+ threshold for spontaneous store overload-induced Ca2+ release (SOICR) [PMID:25156119, PMID:35446340]. CPVT-associated gain-of-function mutations sensitize the channel to luminal and/or cytosolic Ca2+ and lower this threshold, increasing arrhythmogenic spontaneous release, whereas loss-of-function mutations suppress Ca2+ activation, abolish SOICR, and produce a distinct CRDS phenotype that can include left ventricular non-compaction [PMID:16239587, PMID:23746327, PMID:37325910, PMID:31028179]. Channel output is set by an integrated regulatory layer: calmodulin (CaM) binds RyR2 with high affinity at multiple Ca2+-dependent CaM-binding domains and inhibits the channel, and loss of CaM affinity—whether through disease, post-translational modification, or arrhythmogenic CaM mutations—elevates Ca2+ leak and arrhythmia [PMID:12614169, PMID:24186966, PMID:30530841, PMID:31230402]. CaMKIIδ phosphorylation at S2814 drives a pathological conformational state with reduced CaM affinity and SR Ca2+ leak that underlies heart failure, atrial fibrillation, and catecholaminergic arrhythmia, while PKA phosphorylation at S2030 governs CaM-dependent inactivation, the Ca2+ release termination threshold, and Ca2+ alternans [PMID:22511749, PMID:22158709, PMID:27318036, PMID:33375811, PMID:36583384]. Redox control adds a further axis: S-nitrosylation and cysteine oxidation render the channel leaky, ERp44 binding to luminal Cys4806 is redox-sensitive, and SR Ca2+ release feeds a mitochondrial ROS feedback loop that further oxidizes RyR2 [PMID:20080623, PMID:35086342, PMID:32444920, PMID:25106424]. RyR2 function is additionally stabilized by integrin β1D and coupled to partner channels, including KCa3.1, SK2, and Cx43 hemichannels at membrane junctions [PMID:31461656, PMID:31841141, PMID:32122157, PMID:24747296]. Beyond the heart, RyR2 shapes cardiomyocyte mitochondrial Ca2+ uptake and glucose oxidation [PMID:27621312], regulates pancreatic β-cell insulin secretion and survival via IRBIT and calpain-10 [PMID:25844899, PMID:15044459, PMID:35562179], drives hippocampal nuclear Ca2+ signaling for CREB-dependent transcription and synaptic strength [PMID:34389673, PMID:27482086], and activates Ca2+-AKT signaling that promotes CD8+ T cell exhaustion [PMID:38451948].","teleology":[{"year":2001,"claim":"Establishing that RYR2 mutations cause inherited arrhythmia defined the gene as the disease-relevant cardiac SR Ca2+ release channel and located causal mutations across three structural regions.","evidence":"Genomic structure elucidation and mutation cosegregation analysis in ARVD2/CPVT families","pmids":["11159936","11157710"],"confidence":"High","gaps":["Genetics alone did not reveal whether mutations gain or lose function","No biophysical mechanism for arrhythmia at the channel level"]},{"year":2002,"claim":"Quantifying mutation effects on FKBP12.6 binding offered an early candidate mechanism distinguishing arrhythmia-associated from ARVD2 mutations.","evidence":"Quantitative yeast two-hybrid assay of RyR2-FKBP12.6 interaction across mutations","pmids":["12459180"],"confidence":"Medium","gaps":["Single binding method without channel functional readout","Later work found no FKBP12.6-RyR2 interaction change for several disease mutations"]},{"year":2003,"claim":"Defining how calmodulin inhibits RyR2 across all Ca2+ concentrations identified CaM as a key constitutive negative regulator and mapped the determinant to its C-terminal Ca2+-binding lobe.","evidence":"In vitro RyR2 activity assays with Ca2+-insensitive CaM mutants and ryanodine binding","pmids":["12614169"],"confidence":"High","gaps":["Did not map the RyR2 CaM-binding domains involved","In vitro reconstitution did not establish in situ affinity or disease relevance"]},{"year":2005,"claim":"Resolving the channel-level defect of disease mutations showed enhanced luminal Ca2+ sensitivity and SOICR as the unifying gain-of-function mechanism, redirecting attention away from FKBP12.6.","evidence":"Inducible HEK293 RyR2 cell lines, single-channel recording, ryanodine binding, and Ca2+ imaging across six mutations","pmids":["16239587"],"confidence":"High","gaps":["Did not resolve how N-terminal versus C-terminal mutations converge on the same gating change","Quantitative link to clinical onset not yet established"]},{"year":2013,"claim":"Linking an N-terminal CPVT mutation to reduced domain thermal stability and dual Ca2+ sensitization began to connect channel structure to SOICR dysregulation.","evidence":"Inducible HEK293 SOICR assay, single-channel recording, and thermal stability assay of recombinant N-terminal fragment","pmids":["23746327"],"confidence":"High","gaps":["Full-length structural consequence not determined","Mechanism of inter-domain coupling to the pore unresolved"]},{"year":2011,"claim":"Phospho-site knock-in epistasis established CaMKII phosphorylation at S2814, not PKA at S2808, as the site required for SR Ca2+ leak, delayed afterdepolarizations, and atrial fibrillation.","evidence":"Double knock-in mice (FKBP12.6-/-:S2814A and :S2808A), confocal Ca2+ imaging, patch clamp, intracardiac pacing","pmids":["22158709"],"confidence":"High","gaps":["Did not define the conformational change produced by S2814 phosphorylation","Upstream CaMKII isoform not yet isolated"]},{"year":2012,"claim":"Showing S2814 phosphorylation rises in heart failure and that S2814A mice resist pressure-overload extended the CaMKII-leak mechanism to acquired cardiac disease.","evidence":"S2814A knock-in mice, transverse aortic constriction, Ca2+ imaging, and human non-ischemic HF tissue","pmids":["22511749"],"confidence":"High","gaps":["Did not separate RyR2 leak from other CaMKII substrate contributions to HF","Therapeutic targeting not addressed"]},{"year":2013,"claim":"Measuring CaM-RyR2 affinity in situ established that most Z-line CaM is RyR2-bound and that reduced affinity drives Ca2+ waves and stress arrhythmia, making CaM binding a functional disease axis.","evidence":"FRET in permeabilized cardiomyocytes, RyR2(ADA/+) knock-in mice, and post-MI rat HF model","pmids":["24186966"],"confidence":"High","gaps":["Did not identify what lowers CaM affinity in disease at the molecular level","Number and identity of CaM-binding domains not resolved"]},{"year":2014,"claim":"Defining the cytosolic/luminal Ca2+ and Mg2+ sensitivities of native human RyR2 and the SK2 functional coupling characterized the channel's intrinsic gating and an output partner.","evidence":"Single-channel bilayer recordings of native human/sheep/rat RyR2; co-IP and patch clamp for SK2 coupling","pmids":["25156119","24747296"],"confidence":"High","gaps":["Species differences in luminal sensitivity mechanistically unexplained","SK2 co-IP from single lab without structural interface"]},{"year":2015,"claim":"Genetic dissection of CaMKIIδ and the discovery of β-cell and metabolic roles broadened RyR2 leak beyond contraction to chronic catecholamine cardiomyopathy and extracardiac biology.","evidence":"CaMKIIδ-KO and S2814A mice with chronic isoproterenol; transgenic CPVT mice and human islet Ca2+/ER stress assays","pmids":["26080362","25844899"],"confidence":"High","gaps":["Tissue-specific regulation of RyR2 leak in islets versus heart not unified","Did not establish the β-cell RyR2 interactome"]},{"year":2016,"claim":"Connecting S2814 phosphorylation to a defined pathological conformation (increased DPc10 access, reduced CaM affinity) and dantrolene rescue mechanistically unified phosphorylation, CaM regulation, and leak; parallel work defined neuronal RyR2 roles in synapses, cardiac mitochondrial metabolism, and β-cell survival.","evidence":"S2814D/A knock-in mice, DPc10 conformational and FRET CaM assays; RyR2-R176Q neuronal knock-in; cardiac Ryr2 haploinsufficient mice; β-cell calpain-10 apoptosis assays","pmids":["27318036","27482086","27621312","15044459"],"confidence":"High","gaps":["Structural basis of the DPc10-accessible state not solved","Extracardiac mechanisms each rest on individual models"]},{"year":2019,"claim":"Mapping four Ca2+-dependent CaM-binding domains and showing phosphorylation gates CaM inhibition in human RyR2 resolved how CaM senses Ca2+ and integrates phosphorylation state to control the channel.","evidence":"Fluorescence anisotropy of CaMBD peptides; single-channel bilayer and FRET with phosphomimetic knock-in RyR2; systematic study of 14 arrhythmogenic CaM mutations","pmids":["30530841","30928430","31230402"],"confidence":"High","gaps":["How phosphorylation alters CaMBD-CaM contacts structurally unresolved","Integration of the four CaMBDs in the intact tetramer not visualized"]},{"year":2020,"claim":"PKA-S2030 control of CaM-dependent inactivation and Ca2+ alternans, an integrin β1D-RyR2 stabilizing interaction, a mitochondrial ROS feedback loop, RyR2-Cx43 hemichannel coupling, and RyR2 inhibition as flecainide's antiarrhythmic mechanism collectively expanded the regulatory and pharmacological map.","evidence":"In vivo CaM-variant delivery and Ca2+ imaging; integrin β1D bilayer reconstitution and KO mice; genetic ROS/Ca2+ probes with dominant-negative MCU; PLA/co-IP and Ca2+-clamp for Cx43; matched flecainide analogues across bilayer, sodium-channel, and in vivo CPVT assays","pmids":["33375811","32122157","32444920","31841141","33297863"],"confidence":"High","gaps":["Spatial relationship between S2030 and S2814 phospho-control not unified","Integrin and Cx43 interaction interfaces not structurally defined"]},{"year":2021,"claim":"Identifying loss-of-function mutations causing a CRDS distinct from CPVT, plus neuronal nuclear Ca2+ signaling roles, established the bidirectional disease spectrum and CNS reach of RyR2.","evidence":"Bilayer single-channel and SOICR/dominant-negative studies of E4146K/G4935R; pharmacological RyR inhibition with CREB/Npas4 readouts in hippocampal neurons","pmids":["33825858","34389673"],"confidence":"High","gaps":["In vivo cardiac phenotype of these LOF mutations not yet shown at this stage","Neuronal nuclear Ca2+ link rests on pharmacology without genetic RyR2 ablation"]},{"year":2022,"claim":"Defining resting cytosolic activity (Arest) as the determinant of the luminal Ca2+ threshold and correlating it with patient onset age, plus the redox-sensitive ERp44-Cys4806 interaction, provided quantitative and molecular bases for arrhythmogenesis.","evidence":"HEK293 cytosolic/ER Ca2+ measurements with kinetic modeling across CPVT mutations; co-IP, C4806 mutagenesis, molecular dynamics, and ROS biosensor for ERp44/Ero1α","pmids":["35446340","35086342"],"confidence":"High","gaps":["Arest framework derived in HEK293, not native myocytes","Structural docking of ERp44 on the luminal face not resolved"]},{"year":2023,"claim":"Genetic RyR2 depletion linking ER stress/ATF4 signaling to cardiomyocyte maturation, and an LOF I4855M knock-in producing LVNC, connected RyR2 channel function to development and structural cardiomyopathy.","evidence":"Cas9/AAV9 somatic RYR2 knockout with RNA-Seq/ChIP-Seq and ATF4 manipulation; I4855M knock-in mice with echocardiography and Ca2+ imaging","pmids":["35576474","37325910"],"confidence":"High","gaps":["How channel activity is transduced to ATF4/ER stress not mechanistically traced","Developmental versus adult contributions of RyR2 not separated"]},{"year":null,"claim":"How the regulatory inputs (CaM occupancy, S2814/S2030 phosphorylation, redox modifications, ERp44 and integrin β1D binding) are spatially integrated within the intact tetramer to set open probability, and how tissue-specific interactomes redirect RyR2 output in neurons, β cells, and T cells, remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No unified structural model integrating phospho-, CaM-, and redox-control sites","Extracardiac RyR2 partner complexes not fully reconstituted","Causal link between channel conformational states and downstream transcription/metabolism incompletely mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[32,30]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[16,33,32]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[20,21,41]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[18,22]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,30]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,1,26,35]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[38,34]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[33,19,22]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[18,16]}],"complexes":["RyR2-calstabin2 (FKBP12.6) complex","Cav1.3-RyR2-KCa3.1 junctional complex","RyR2-calmodulin complex"],"partners":["CALM1","FKBP12.6","ERP44","ITGB1 (INTEGRIN Β1D)","GJA1 (CX43)","KCNN2 (SK2)","JPH3","IRBIT"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q92736","full_name":"Ryanodine receptor 2","aliases":["Cardiac muscle ryanodine receptor","Cardiac muscle ryanodine receptor-calcium release channel","Type 2 ryanodine receptor"],"length_aa":4967,"mass_kda":564.6,"function":"Cytosolic calcium-activated calcium channel that mediates the release of Ca(2+) from the sarcoplasmic reticulum into the cytosol and thereby plays a key role in triggering cardiac muscle contraction. Aberrant channel activation can lead to cardiac arrhythmia. In cardiac myocytes, calcium release is triggered by increased Ca(2+) cytosolic levels due to activation of the L-type calcium channel CACNA1C. The calcium channel activity is modulated by formation of heterotetramers with RYR3. Required for cellular calcium ion homeostasis. Required for embryonic heart development","subcellular_location":"Sarcoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q92736/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RYR2","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/RYR2","total_profiled":1310},"omim":[{"mim_id":"619863","title":"JUNCTOPHILIN 4; JPH4","url":"https://www.omim.org/entry/619863"},{"mim_id":"617242","title":"TRANS-2,3-ENOYL-CoA REDUCTASE-LIKE PROTEIN; TECRL","url":"https://www.omim.org/entry/617242"},{"mim_id":"615441","title":"CARDIAC ARRHYTHMIA SYNDROME, WITH OR WITHOUT SKELETAL MUSCLE WEAKNESS; CARDAR","url":"https://www.omim.org/entry/615441"},{"mim_id":"614916","title":"VENTRICULAR TACHYCARDIA, CATECHOLAMINERGIC POLYMORPHIC, 4; CPVT4","url":"https://www.omim.org/entry/614916"},{"mim_id":"614021","title":"VENTRICULAR TACHYCARDIA, CATECHOLAMINERGIC POLYMORPHIC, 3; CPVT3","url":"https://www.omim.org/entry/614021"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Plasma membrane","reliability":"Uncertain"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"heart muscle","ntpm":137.9}],"url":"https://www.proteinatlas.org/search/RYR2"},"hgnc":{"alias_symbol":["ARVC2","VTSIP"],"prev_symbol":["ARVD2"]},"alphafold":{"accession":"Q92736","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92736","model_url":"","pae_url":"","plddt_mean":null},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RYR2","jax_strain_url":"https://www.jax.org/strain/search?query=RYR2"},"sequence":{"accession":"Q92736","fasta_url":"https://rest.uniprot.org/uniprotkb/Q92736.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q92736/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92736"}},"corpus_meta":[{"pmid":"11159936","id":"PMC_11159936","title":"Identification of mutations in the cardiac ryanodine receptor gene in families affected with arrhythmogenic right ventricular cardiomyopathy type 2 (ARVD2).","date":"2001","source":"Human molecular 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Heart and circulatory physiology","url":"https://pubmed.ncbi.nlm.nih.gov/34270372","citation_count":13,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":58665,"output_tokens":10501,"usd":0.166755,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":21253,"output_tokens":6272,"usd":0.131532,"stage2_stop_reason":"end_turn"},"total_usd":0.298287,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"RYR2 mutations (in N-terminal, central, and C-terminal regions) cause ARVD2/CPVT; RyR2 encodes the cardiac sarcoplasmic reticulum Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling.\",\n      \"method\": \"Genomic structure elucidation, mutation identification by sequencing in affected families, cosegregation analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — independently replicated across two papers (PMID:11159936 and PMID:11157710), cosegregation demonstrated in multiple independent families\",\n      \"pmids\": [\"11159936\", \"11157710\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Disease-linked RyR2 mutations (from N-terminal, central, and C-terminal regions) enhance the sensitivity of the channel to luminal (but not cytosolic) Ca2+ activation and increase the propensity for store overload-induced Ca2+ release (SOICR); no alteration in FKBP12.6-RyR2 interaction was detected.\",\n      \"method\": \"Stable inducible HEK293 cell lines expressing mutant RyR2, single-channel analysis, [3H]ryanodine binding, single-cell Ca2+ imaging in HL-1 cardiac cells\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (single-channel recordings, ryanodine binding, cellular Ca2+ imaging) across 6 mutations in two cell types\",\n      \"pmids\": [\"16239587\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VTSIP-associated RyR2 point mutations increase, while ARVD2-associated mutations decrease, binding of RyR2 to its gating protein FKBP12.6, as measured by quantitative yeast two-hybrid assay.\",\n      \"method\": \"Quantitative yeast two-hybrid assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single method (yeast two-hybrid), but multiple mutations tested with consistent directional effects\",\n      \"pmids\": [\"12459180\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In the mdx mouse model of Duchenne muscular dystrophy, RyR2 is S-nitrosylated and depleted of calstabin2 (FKBP12.6), resulting in leaky RyR2 channels and diastolic SR Ca2+ leak that triggers cardiac arrhythmias; stabilizing the RyR2-calstabin2 complex with S107 inhibited SR Ca2+ leak and prevented arrhythmias in vivo.\",\n      \"method\": \"Co-immunoprecipitation, S-nitrosylation assay, confocal Ca2+ imaging, in vivo arrhythmia monitoring in mdx mice\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (biochemistry, imaging, in vivo pharmacology) with clear mechanistic rescue\",\n      \"pmids\": [\"20080623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CaMKII phosphorylation of RyR2 at S2814 (but not PKA phosphorylation at S2808) is increased in non-ischemic heart failure; knock-in mice with inactivated S2814 (S2814A) are protected from pressure-overload heart failure and exhibit reduced SR Ca2+ leak.\",\n      \"method\": \"Knock-in mouse model (S2814A), transverse aortic constriction, confocal Ca2+ imaging, Western blotting\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knock-in with defined phosphorylation site, multiple phenotypic readouts, confirmed in human non-ischemic HF tissue\",\n      \"pmids\": [\"22511749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"CaMKII phosphorylation of RyR2 at S2814 (not S2808) is required for SR Ca2+ leak, delayed afterdepolarizations (DADs), and atrial fibrillation induction in FKBP12.6-knockout mice; genetic inhibition of S2814 phosphorylation (S2814A knock-in) reduces Ca2+ spark frequency and prevents AF.\",\n      \"method\": \"Double knock-in mouse models (FKBP12.6-/-:S2814A and FKBP12.6-/-:S2808A), confocal Ca2+ imaging, patch clamp, intracardiac pacing\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with two distinct phospho-site knock-ins, multiple functional readouts\",\n      \"pmids\": [\"22158709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"CaM inhibits RyR2 at all Ca2+ concentrations (100 nM–1 mM), increasing the Ca2+ EC50 of RyR2 7–10-fold; C-terminal Ca2+-binding sites on CaM determine the inhibitory effect, and apoCaM (Ca2+-binding deficient mutant) activates RyR2 and acts as a competitive inhibitor of Ca2+CaM regulation.\",\n      \"method\": \"Biochemical assay of RyR2 activity with Ca2+-insensitive CaM mutants, [3H]ryanodine binding\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with panel of CaM mutants, multiple binding/activity measurements\",\n      \"pmids\": [\"12614169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In situ, CaM binds RyR2 with high affinity (Kd ~10–20 nM); >90% of Z-line CaM in cardiomyocytes is RyR2-bound; reduced CaM-RyR2 affinity (~3-fold increase in Kd) occurs in post-MI rat heart failure; reduced CaM binding in RyR2(ADA/+) knock-in mice increases Ca2+ wave production and stress-induced ventricular arrhythmia.\",\n      \"method\": \"FRET in permeabilized cardiomyocytes, RyR2(ADA/+) knock-in mouse model, post-MI rat heart failure model\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (FRET, genetic knock-in, disease model) with functional consequence\",\n      \"pmids\": [\"24186966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CaMKII phosphorylation of RyR2 at S2814 promotes a pathological RyR2 conformational state (increased DPc10 access, reduced CaM affinity, elevated Ca2+ leak); dantrolene restores CaM affinity, reduces DPc10 access, and suppresses SR Ca2+ leak and ventricular tachycardia in RyR2-S2814D mice.\",\n      \"method\": \"Phosphomimetic/phosphoablative knock-in mice (S2814D/S2814A), DPc10 peptide conformational assay, FRET-based CaM affinity measurement, confocal Ca2+ imaging, in vivo arrhythmia assessment\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods with genetic and pharmacological interventions validating the same mechanistic pathway\",\n      \"pmids\": [\"27318036\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CaMKIIδ-dependent phosphorylation of RyR2-S2814 mediates SR Ca2+ leak in response to β-adrenergic stimulation; CaMKIIδ-KO and S2814A knock-in mice are protected from cardiomyopathy induced by chronic isoproterenol, without blocking hypertrophy.\",\n      \"method\": \"CaMKIIδ-KO and S2814A knock-in mice, Langendorff heart perfusion, confocal Ca2+ imaging, chronic isoproterenol treatment\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two independent genetic models with consistent phenotype, multiple functional readouts\",\n      \"pmids\": [\"26080362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CaM binds to four CaM-binding domains (CaMBD1a, -1b, -2, -3) in RyR2 in a Ca2+-dependent manner; the CaM C-domain anchors to CaMBD2 (essentially Ca2+-saturated at rest), while the CaM N-domain dynamically senses Ca2+ in the physiological range when complexed with CaMBD2 or CaMBD3.\",\n      \"method\": \"Fluorescence anisotropy with TAMRA-labeled CaMBD peptides, Ca2+ titrations, isolated CaM domain binding experiments\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with multiple CaM domains, quantitative binding measurements across Ca2+ concentrations\",\n      \"pmids\": [\"30530841\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Phosphorylation of human RyR2 at S2808 or S2814 is necessary and sufficient for CaM inhibitory activity on RyR2; CaM (100 nM) inhibits RyR2 from failing human hearts (~50%) but has no effect on RyR2 from healthy human hearts, a difference attributable to phosphorylation state.\",\n      \"method\": \"Artificial lipid bilayer single-channel recording, FRET (donor-FKBP12.6/acceptor-CaM), Ca2+ spark measurements in phosphomimetic/phosphoablated RyR2 knock-in cardiomyocytes\",\n      \"journal\": \"Journal of molecular and cellular cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — single-channel electrophysiology, FRET, and genetic knock-in models in multiple species\",\n      \"pmids\": [\"30928430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Ca2+-CaM dependent inactivation of RyR2 is a major determinant of Ca2+ alternans; CaM gain-of-function (CaM-M37Q) promotes and CaM loss-of-function (CaM-1-4) suppresses Ca2+ alternans in intact working mouse hearts; PKA phosphorylation of RyR2 at S2030 modulates CaM-dependent inactivation and Ca2+ alternans.\",\n      \"method\": \"In vivo adenoviral delivery of CaM variants into mouse myocardium, confocal Ca2+ imaging in Langendorff-perfused hearts, numerical modeling\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct in vivo manipulation of CaM function with gain/loss-of-function variants, validated by numerical model across 9 experimental conditions\",\n      \"pmids\": [\"33375811\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PKA phosphorylation of RyR2 at S2030 governs Ca2+ release termination threshold via CaM-dependent inactivation; S2030L mutation abolishes CaM-wild-type and PKA effects on termination but preserves CaMKII effects, placing S2030 within the CaM-dependent inactivation pathway.\",\n      \"method\": \"ER Ca2+ imaging in HEK293 cells, S2030L knock-in mouse model, confocal Ca2+ imaging, pharmacological CaMKII/PKA inhibition\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knock-in mouse combined with HEK293 functional studies and pharmacological dissection of PKA vs CaMKII pathways\",\n      \"pmids\": [\"36583384\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"RyR2 channel inhibition (not solely sodium channel block) is the principal mechanism of flecainide's antiarrhythmic action in CPVT; N-methylated flecainide analogues that lose RyR2 inhibitory potency (while retaining sodium channel block) fail to suppress CPVT arrhythmias in Casq2-/- mice.\",\n      \"method\": \"Synthesis of N-methylated flecainide analogues, lipid bilayer RyR2 single-channel recordings, HEK293 sodium channel assays, membrane-permeabilized and voltage-clamped Casq2-/- cardiomyocytes, in vivo catecholamine challenge\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — chemical biology approach with matched analogues, multiple orthogonal assays, in vitro and in vivo validation\",\n      \"pmids\": [\"33297863\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The CPVT-associated RyR2 G230C N-terminal mutation enhances SOICR propensity by sensitizing the channel to both luminal and cytosolic Ca2+ activation, and decreases thermal stability of the N-terminal domain (residues 1–547) of RyR2.\",\n      \"method\": \"Stable inducible HEK293 cell lines, single-cell Ca2+ imaging (SOICR assay), single-channel recordings, [3H]ryanodine binding, thermal stability assay of recombinant N-terminal fragment\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal methods including structural stability assay and single-channel recordings\",\n      \"pmids\": [\"23746327\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"RyR2 in pancreatic β cells regulates insulin secretion and glucose homeostasis; leaky RyR2 channels (via oxidation and S-nitrosylation) cause ER stress, mitochondrial dysfunction, and decreased insulin release in CPVT mice and diabetic human islets.\",\n      \"method\": \"Transgenic CPVT RyR2 mice, islet isolation and Ca2+ imaging, ER stress assays, mitochondrial function assays, pharmacological Ca2+ leak inhibition\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal mechanistic assays in transgenic mice and human islets with pharmacological rescue\",\n      \"pmids\": [\"25844899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Inhibiting RyR2 in pancreatic β cells markedly increases apoptosis via a caspase-3-independent, calpain-10-dependent death pathway; RyR2 activity suppresses calpain-10-mediated apoptosis in β cells.\",\n      \"method\": \"Pharmacological inhibition (ryanodine), pharmacological and genetic inhibition of calpain-10 in human and mouse β cells, apoptosis assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological and genetic approaches in human and murine cells, multiple orthogonal functional assays\",\n      \"pmids\": [\"15044459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"RyR2 Ca2+ release in cardiomyocytes specifically promotes mitochondrial Ca2+ uptake and glucose oxidation via pyruvate dehydrogenase activation; 50% reduction in Ryr2 protein (haploinsufficiency) decreases mitochondrial Ca2+ signals and impairs glucose oxidation without affecting cardiac contraction.\",\n      \"method\": \"Inducible heart-specific Ryr2 haploinsufficient mice (cRyr2Δ50), confocal Ca2+ imaging, metabolic flux analysis, metabolomics, proteomics, transcriptomics\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic model with multiple orthogonal metabolic and Ca2+ imaging assays establishing specific metabolic pathway\",\n      \"pmids\": [\"27621312\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ERp44 associates with RyR2 via intraluminal cysteine 4806 in a redox-sensitive manner; Ero1α-mediated SR oxidation causes ERp44 dissociation from the RyR2 complex, increasing RyR2 Ca2+ channel activity and promoting proarrhythmic spontaneous Ca2+ release.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis (C4806), molecular dynamics simulation, genetic Ero1α overexpression/knockdown, intra-SR ROS biosensor (ERroGFP), pharmacological inhibition (EN460), rat TAB model\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — mutagenesis of interaction site, molecular dynamics, multiple orthogonal biochemical and functional approaches\",\n      \"pmids\": [\"35086342\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Junctophilin proteins (JPH3/JPH4) tether a Cav1.3-RyR2-KCa3.1 tripartite complex at the plasma membrane-ER junction in hippocampal CA1 neurons; disruption of this complex (by JPH3/4 shRNA or antibody infusion) dissociates Cav1.3-RyR2-KCa3.1 and reduces the slow AHP current.\",\n      \"method\": \"dSTORM super-resolution microscopy, FRET microscopy, shRNA knockdown, antibody infusion, patch clamp electrophysiology in CA1 neurons\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — super-resolution imaging and FRET confirm complex proximity, genetic and antibody disruption with electrophysiological functional readout\",\n      \"pmids\": [\"31461656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RyR2 physically interacts with Cx43 (<40 nm proximity by PLA); RyR activation and intracellular Ca2+ elevation together are necessary to open Cx43 hemichannels at diastolic membrane potential; a RyR-mimicking peptide (RyRHCIp) inhibits RyR/Ca2+-triggered HC activation.\",\n      \"method\": \"Proximity ligation assay, co-immunoprecipitation, whole-cell patch clamp, molecular modelling, Ca2+ clamp experiments\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP + PLA confirming physical interaction, functional demonstration with Ca2+-clamp and peptide inhibitor\",\n      \"pmids\": [\"31841141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Augmented RyR2 activity (pharmacological or genetic CPVT mutation) increases mitochondrial ROS emission via altered SR-mitochondrial Ca2+ transfer; mito-ROS in turn oxidizes RyR2, further amplifying proarrhythmic SR Ca2+ release in a positive feedback cycle (leak begets leak); dominant-negative MCU abrogates this effect.\",\n      \"method\": \"Spatially restricted genetic ROS probes, mitochondrial Ca2+ probe (mtRCamp1h), dominant-negative MCU expression, CPVT mouse ventricular myocytes, pharmacological ROS scavenging\",\n      \"journal\": \"Basic research in cardiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic ROS probes, dominant-negative genetic tool, multiple orthogonal readouts establishing the feedback mechanism\",\n      \"pmids\": [\"32444920\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A single RyR2 point mutation E4872Q that reduces RyR2 open time prevents neuronal hyperexcitability, memory impairment, dendritic spine loss, and neuronal cell death in 5xFAD Alzheimer's disease mice; the mechanism involves upregulation of hippocampal CA1 A-type K+ current.\",\n      \"method\": \"RyR2-E4872Q knock-in mouse crossed with 5xFAD, behavioral tests, patch clamp (A-type K+ current), pharmacological treatment (R-carvedilol)\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knock-in with defined channel property change, pharmacological validation, specific electrophysiological mechanism identified\",\n      \"pmids\": [\"32966798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The leaky RyR2-R176Q gain-of-function mutation in neurons selectively strengthens excitatory (but not inhibitory) synapses and lowers the threshold for spreading depolarization in the dorsal medulla, leading to cardiorespiratory collapse; this links neuronal RyR2 Ca2+ dysregulation to brainstem spreading depolarization as a mechanism of sudden death.\",\n      \"method\": \"RyR2-R176Q knock-in mouse model (RQ/+), in vitro electrophysiology (excitatory/inhibitory synapse recordings), spreading depolarization assay, in vivo EEG/ECG monitoring\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knock-in with mechanistic in vitro and in vivo electrophysiology establishing synapse-specific effect\",\n      \"pmids\": [\"27482086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A RyR2 loss-of-function mutation (I4855M) in the inner vestibule of the pore inhibits caffeine-induced Ca2+ release and exerts a dominant-negative effect on wild-type RyR2 when co-expressed in HEK293 cells.\",\n      \"method\": \"HEK293 cell Ca2+ release assay, homology modelling of RyR2 pore region, co-expression studies\",\n      \"journal\": \"Journal of electrocardiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional cell assay and co-expression dominant-negative study, structural model is in silico only\",\n      \"pmids\": [\"27646203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Two additional RyR2 loss-of-function mutations (E4146K and G4935R) markedly suppress cytosolic and luminal Ca2+ activation of single RyR2 channels; G4935R exerts a dominant-negative effect on wild-type RyR2; these LOF mutations are associated with a distinct arrhythmia syndrome (CRDS) different from CPVT.\",\n      \"method\": \"HEK293 cell SOICR assay, [3H]ryanodine binding, single-channel recordings in lipid bilayers, co-expression dominant-negative studies\",\n      \"journal\": \"Bioscience reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro single-channel electrophysiology with multiple assays (ryanodine binding, SOICR, co-expression) for two distinct mutations\",\n      \"pmids\": [\"33825858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Integrin β1D protein directly stabilizes RyR2 function by decreasing RyR2 open probability, mean open time, and increasing mean close time (lipid bilayer patch clamp); loss of integrin β1D in ARVC leads to RyR2-S2030 hyperphosphorylation and aberrant Ca2+ handling causing catecholamine-sensitive polymorphic ventricular tachycardia.\",\n      \"method\": \"Purified integrin β1D protein + lipid bilayer patch clamp single-channel recordings, cardiac-specific β1D KO mouse model, Western blotting, confocal Ca2+ imaging\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct reconstitution of integrin β1D effect on RyR2 channels in bilayers plus genetic KO mouse with functional phenotype\",\n      \"pmids\": [\"32122157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Doxorubicin and its metabolite doxorubicinol bind to and activate single RyR2 channels, then cause irreversible inhibition via thiol oxidation (reducing thiol groups on RyR2); both effects are reversed/prevented by the reducing agent DTT, identifying oxidation of RyR2 cysteines as the mechanism of secondary inhibition.\",\n      \"method\": \"Single RyR2 channel recordings, thiol group quantification, SR vesicle Ca2+ uptake assay, drug washout experiments\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro single-channel electrophysiology with mechanistic dissection using reducing agent and washout\",\n      \"pmids\": [\"25106424\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"All 14 arrhythmogenic CaM mutations tested diminish CaM-dependent inhibition of RyR2-mediated Ca2+ release and increase SOICR; many CaM mutations fail to inhibit or even facilitate RyR2-mediated Ca2+ release at elevated cytosolic Ca2+, and alter Ca2+-dependency of CaM binding to the RyR2 CaM-binding domain.\",\n      \"method\": \"HEK293 cells expressing RyR2 with arrhythmogenic CaM mutations, SOICR Ca2+ imaging, permeabilized cell Ca2+ release assay, CaM-binding domain interaction studies\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic study of 14 mutations with multiple orthogonal Ca2+ release assays\",\n      \"pmids\": [\"31230402\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Human RyR2 displays cytoplasmic Ca2+ activation (Ka ~4 µM) inhibited by cytoplasmic Mg2+ (Ki ~10 µM); luminal Ca2+ activation (Ka ~35 µM) is similar to sheep but distinct from rat; physiological Mg2+ (1 mM) raises Ka for cytoplasmic Ca2+ to ~30 µM in human and sheep RyR2.\",\n      \"method\": \"Artificial lipid bilayer single-channel recordings of native RyR2 from healthy and failing human, sheep, and rat hearts\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro single-channel electrophysiology comparing three species with systematic ion concentration variation\",\n      \"pmids\": [\"25156119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"RyR2-mediated Ca2+ release is necessary and sufficient for activation of SK2 (small-conductance Ca2+-activated K+) channels in atrial cardiomyocytes; SK2 and RyR2 co-immunoprecipitate from native cardiac tissue, indicating a physical interaction.\",\n      \"method\": \"Whole-cell patch clamp, co-immunoprecipitation, lentiviral shRNA knockdown of RyR2, pharmacological RyR2 activation/inhibition, confocal Ca2+ imaging\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP combined with functional patch-clamp and genetic knockdown, single lab\",\n      \"pmids\": [\"24747296\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cytosolic Ca2+-dependent activity of RyR2 at resting Ca2+ (Arest) is the primary determinant of the ER luminal Ca2+ threshold for spontaneous Ca2+ release; CPVT mutations increase Arest and lower the threshold [Ca2+]ER in a manner that correlates with age of disease onset in patients.\",\n      \"method\": \"HEK293 cell expression of WT and CPVT-mutant RYR2, fluorescent Ca2+ indicators for cytosolic and ER Ca2+, in silico modeling\",\n      \"journal\": \"The Journal of general physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic in vitro characterization across multiple mutations with quantitative kinetic modeling\",\n      \"pmids\": [\"35446340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RyR2 depletion in cardiomyocytes activates ER stress pathways (including ATF4 upregulation) that perturb cardiomyocyte maturation; tauroursodeoxycholic acid (ER stress alleviator) partially rescues these defects; ATF4 overexpression recapitulates RyR2-depletion phenotype, with protein biosynthesis genes as major ATF4 targets.\",\n      \"method\": \"Cas9/AAV9 somatic RYR2 knockout in cardiomyocytes, genetic mosaic analysis, RNA-Seq, bioChIP-Seq, tauroursodeoxycholic acid treatment, ATF4 overexpression\",\n      \"journal\": \"Cardiovascular research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple orthogonal genomic and functional methods establishing ER stress as mechanistic intermediary\",\n      \"pmids\": [\"35576474\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"RyR2-mediated Ca2+ release in hippocampal neurons contributes to nuclear Ca2+ signals generated by neuronal activity; RyR-mediated Ca2+ release is required for CREB phosphorylation, Npas4 expression, and RyR2 upregulation in response to gabazine or high-frequency stimulation.\",\n      \"method\": \"Confocal Ca2+ imaging in primary hippocampal neurons, pharmacological RyR inhibition with ryanodine, glutamate uncaging, high-frequency field stimulation, Western blot\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live Ca2+ imaging with pharmacological inhibition showing RyR2-dependent signal transduction to nucleus\",\n      \"pmids\": [\"34389673\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RyR2 loss-of-function mutation I4855M increases Ca2+-induced Ca2+ release gain, abolishes SOICR, elevates SR Ca2+ load, prolongs Ca2+ transient decay, and elevates end-diastolic Ca2+ upon rapid pacing, providing a mechanism for CRDS-associated LVNC.\",\n      \"method\": \"I4855M knock-in mouse model, echocardiography, confocal Ca2+ imaging, immunoblotting, histological analysis\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knock-in mouse recapitulating human LVNC phenotype, multiple orthogonal Ca2+ handling measurements\",\n      \"pmids\": [\"37325910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In ARVC hearts, integrin β1D deficiency leads to RyR2-S2030 hyperphosphorylation through a DSP-loss → ERK1/2-fibronectin-ubiquitin/lysosome pathway, causing RyR2 dysfunction and catecholamine-sensitive ventricular tachycardia.\",\n      \"method\": \"Protein mass spectrometry of ARVC hearts, cardiac-specific β1D KO mouse, Western blotting, confocal Ca2+ imaging\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic pathway established in KO mouse model with human tissue correlation, single lab\",\n      \"pmids\": [\"32122157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"KN93, widely used as a CaMKII inhibitor, directly binds CaM and disrupts high-affinity CaM-NaV1.5 interaction and alters NaV1.5 channel function; KN93 also increases RyR2 Ca2+ release in cardiomyocytes independently of CaMKII, by interfering with CaM binding to RyR2.\",\n      \"method\": \"X-ray crystallography (CaM-KN93 structure), NMR spectroscopy, stopped-flow kinetics, NaV1.5 functional assay, confocal Ca2+ imaging in cardiomyocytes\",\n      \"journal\": \"Cell calcium\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure combined with biophysical and functional assays establishing CaM-mediated off-target mechanism\",\n      \"pmids\": [\"31401388\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CD38 expression on CD8+ T cells elevates intracellular Ca2+ through RyR2 Ca2+ channel activation, promoting chronic AKT activation and TCF1 loss leading to terminal CD8+ T cell exhaustion; RyR2 knockdown in CD8+ T cells maintains TCF1 levels and improves anti-tumor responses and responsiveness to anti-PD1 therapy.\",\n      \"method\": \"Genetic ablation of CD38, RyR2 knockdown in CD8+ T cells, Ca2+ imaging, AKT inhibition, single-cell RNA sequencing, in vivo tumor models\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockdown with multiple functional readouts in T cells, single lab; ortholog of canonical cardiac channel in immunological context\",\n      \"pmids\": [\"38451948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RyR2 deletion from INS-1 β cells (RyR2KO) reduces IRBIT protein levels, increases IP3R activity, reduces insulin content, impairs insulin secretion, reduces INS1 and INS2 mRNA, and increases nuclear AHCY with increased exonic DNA methylation; RyR2 and IRBIT co-regulate insulin gene expression and secretion.\",\n      \"method\": \"CRISPR knockout of RyR2 in INS-1 cells, IRBIT KO, insulin secretion assays, RT-PCR, DNA methylation analysis, exploratory proteomics\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with multiple functional readouts; mechanism of IRBIT regulation is correlative rather than directly reconstituted\",\n      \"pmids\": [\"35562179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"RyR2-P2328S mutation from arrhythmic RyR2S/S mice shifts Ca2+ activation 10-fold (AC50 from ~3.5 µM to ~320 nM) and dramatically shifts Ca2+ inactivation threshold >1000-fold (IC50 from ~50 mM to ≤7 µM, within systolic Ca2+ range), without changes in phosphorylation or FKBP12 binding.\",\n      \"method\": \"Artificial lipid bilayer single-channel recordings from RyR2S/S mouse hearts, Western blotting for phosphorylation and FKBP binding\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro single-channel electrophysiology with quantitative Ca2+ dose-response, biochemical controls\",\n      \"pmids\": [\"31028179\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"RyR2 clusters in the periphery of live ventricular myocytes show irregular distribution and dynamic movement (detected by GFP-tagged RyR2 knock-in), unlike the ordered arrays in the interior; peripheral cluster movement is modulated by external Ca2+ and RyR2 activators/inhibitors, and peripheral clusters generate Ca2+ release similar to interior clusters.\",\n      \"method\": \"GFP-RyR2 knock-in mouse model, confocal imaging, TIRF microscopy, simultaneous Ca2+/GFP imaging in live ventricular myocytes and intact hearts\",\n      \"journal\": \"Biophysical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging with genetically tagged channel demonstrating dynamic subcellular localization with functional correlate\",\n      \"pmids\": [\"29401432\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RyR2 is the tetrameric cardiac sarcoplasmic reticulum Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling; it is regulated by luminal and cytosolic Ca2+, Mg2+, calmodulin (which inhibits RyR2 at all Ca2+ concentrations and whose binding is modulated by phosphorylation state), FKBP12.6 (calstabin2), and post-translational modifications including CaMKII phosphorylation at S2814 (promoting leak and arrhythmia), PKA phosphorylation at S2030 (modulating CaM-dependent inactivation and Ca2+ alternans), S-nitrosylation, and redox oxidation; gain-of-function mutations enhance luminal Ca2+ sensitivity and SOICR causing CPVT/ARVD2, while loss-of-function mutations reduce Ca2+ release causing CRDS; beyond the heart, RyR2 operates in pancreatic β cells (regulating insulin secretion via IRBIT), hippocampal neurons (mediating nuclear Ca2+ signals for CREB phosphorylation and synaptic plasticity), and T cells (activating Ca2+-AKT signaling).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RYR2 encodes the tetrameric cardiac sarcoplasmic reticulum (SR) Ca2+ release channel that mediates Ca2+-induced Ca2+ release during excitation-contraction coupling, and gain- and loss-of-function mutations distributed across its N-terminal, central, and C-terminal regions cause the inherited arrhythmias ARVD2/CPVT and CRDS [#0, #26]. The channel is gated by cytosolic Ca2+ activation and Mg2+ inhibition together with luminal Ca2+, and its resting cytosolic Ca2+ sensitivity sets the luminal Ca2+ threshold for spontaneous store overload-induced Ca2+ release (SOICR) [#30, #32]. CPVT-associated gain-of-function mutations sensitize the channel to luminal and/or cytosolic Ca2+ and lower this threshold, increasing arrhythmogenic spontaneous release, whereas loss-of-function mutations suppress Ca2+ activation, abolish SOICR, and produce a distinct CRDS phenotype that can include left ventricular non-compaction [#1, #15, #35, #40]. Channel output is set by an integrated regulatory layer: calmodulin (CaM) binds RyR2 with high affinity at multiple Ca2+-dependent CaM-binding domains and inhibits the channel, and loss of CaM affinity—whether through disease, post-translational modification, or arrhythmogenic CaM mutations—elevates Ca2+ leak and arrhythmia [#6, #7, #10, #29]. CaMKII\\u03b4 phosphorylation at S2814 drives a pathological conformational state with reduced CaM affinity and SR Ca2+ leak that underlies heart failure, atrial fibrillation, and catecholaminergic arrhythmia, while PKA phosphorylation at S2030 governs CaM-dependent inactivation, the Ca2+ release termination threshold, and Ca2+ alternans [#4, #5, #8, #12, #13]. Redox control adds a further axis: S-nitrosylation and cysteine oxidation render the channel leaky, ERp44 binding to luminal Cys4806 is redox-sensitive, and SR Ca2+ release feeds a mitochondrial ROS feedback loop that further oxidizes RyR2 [#3, #19, #22, #28]. RyR2 function is additionally stabilized by integrin \\u03b21D and coupled to partner channels, including KCa3.1, SK2, and Cx43 hemichannels at membrane junctions [#20, #21, #27, #31]. Beyond the heart, RyR2 shapes cardiomyocyte mitochondrial Ca2+ uptake and glucose oxidation [#18], regulates pancreatic \\u03b2-cell insulin secretion and survival via IRBIT and calpain-10 [#16, #17, #39], drives hippocampal nuclear Ca2+ signaling for CREB-dependent transcription and synaptic strength [#34, #24], and activates Ca2+-AKT signaling that promotes CD8+ T cell exhaustion [#38].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Establishing that RYR2 mutations cause inherited arrhythmia defined the gene as the disease-relevant cardiac SR Ca2+ release channel and located causal mutations across three structural regions.\",\n      \"evidence\": \"Genomic structure elucidation and mutation cosegregation analysis in ARVD2/CPVT families\",\n      \"pmids\": [\"11159936\", \"11157710\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genetics alone did not reveal whether mutations gain or lose function\", \"No biophysical mechanism for arrhythmia at the channel level\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Quantifying mutation effects on FKBP12.6 binding offered an early candidate mechanism distinguishing arrhythmia-associated from ARVD2 mutations.\",\n      \"evidence\": \"Quantitative yeast two-hybrid assay of RyR2-FKBP12.6 interaction across mutations\",\n      \"pmids\": [\"12459180\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single binding method without channel functional readout\", \"Later work found no FKBP12.6-RyR2 interaction change for several disease mutations\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defining how calmodulin inhibits RyR2 across all Ca2+ concentrations identified CaM as a key constitutive negative regulator and mapped the determinant to its C-terminal Ca2+-binding lobe.\",\n      \"evidence\": \"In vitro RyR2 activity assays with Ca2+-insensitive CaM mutants and ryanodine binding\",\n      \"pmids\": [\"12614169\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the RyR2 CaM-binding domains involved\", \"In vitro reconstitution did not establish in situ affinity or disease relevance\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Resolving the channel-level defect of disease mutations showed enhanced luminal Ca2+ sensitivity and SOICR as the unifying gain-of-function mechanism, redirecting attention away from FKBP12.6.\",\n      \"evidence\": \"Inducible HEK293 RyR2 cell lines, single-channel recording, ryanodine binding, and Ca2+ imaging across six mutations\",\n      \"pmids\": [\"16239587\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how N-terminal versus C-terminal mutations converge on the same gating change\", \"Quantitative link to clinical onset not yet established\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Linking an N-terminal CPVT mutation to reduced domain thermal stability and dual Ca2+ sensitization began to connect channel structure to SOICR dysregulation.\",\n      \"evidence\": \"Inducible HEK293 SOICR assay, single-channel recording, and thermal stability assay of recombinant N-terminal fragment\",\n      \"pmids\": [\"23746327\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length structural consequence not determined\", \"Mechanism of inter-domain coupling to the pore unresolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Phospho-site knock-in epistasis established CaMKII phosphorylation at S2814, not PKA at S2808, as the site required for SR Ca2+ leak, delayed afterdepolarizations, and atrial fibrillation.\",\n      \"evidence\": \"Double knock-in mice (FKBP12.6-/-:S2814A and :S2808A), confocal Ca2+ imaging, patch clamp, intracardiac pacing\",\n      \"pmids\": [\"22158709\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the conformational change produced by S2814 phosphorylation\", \"Upstream CaMKII isoform not yet isolated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Showing S2814 phosphorylation rises in heart failure and that S2814A mice resist pressure-overload extended the CaMKII-leak mechanism to acquired cardiac disease.\",\n      \"evidence\": \"S2814A knock-in mice, transverse aortic constriction, Ca2+ imaging, and human non-ischemic HF tissue\",\n      \"pmids\": [\"22511749\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not separate RyR2 leak from other CaMKII substrate contributions to HF\", \"Therapeutic targeting not addressed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Measuring CaM-RyR2 affinity in situ established that most Z-line CaM is RyR2-bound and that reduced affinity drives Ca2+ waves and stress arrhythmia, making CaM binding a functional disease axis.\",\n      \"evidence\": \"FRET in permeabilized cardiomyocytes, RyR2(ADA/+) knock-in mice, and post-MI rat HF model\",\n      \"pmids\": [\"24186966\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify what lowers CaM affinity in disease at the molecular level\", \"Number and identity of CaM-binding domains not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defining the cytosolic/luminal Ca2+ and Mg2+ sensitivities of native human RyR2 and the SK2 functional coupling characterized the channel's intrinsic gating and an output partner.\",\n      \"evidence\": \"Single-channel bilayer recordings of native human/sheep/rat RyR2; co-IP and patch clamp for SK2 coupling\",\n      \"pmids\": [\"25156119\", \"24747296\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Species differences in luminal sensitivity mechanistically unexplained\", \"SK2 co-IP from single lab without structural interface\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Genetic dissection of CaMKII\\u03b4 and the discovery of \\u03b2-cell and metabolic roles broadened RyR2 leak beyond contraction to chronic catecholamine cardiomyopathy and extracardiac biology.\",\n      \"evidence\": \"CaMKII\\u03b4-KO and S2814A mice with chronic isoproterenol; transgenic CPVT mice and human islet Ca2+/ER stress assays\",\n      \"pmids\": [\"26080362\", \"25844899\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific regulation of RyR2 leak in islets versus heart not unified\", \"Did not establish the \\u03b2-cell RyR2 interactome\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connecting S2814 phosphorylation to a defined pathological conformation (increased DPc10 access, reduced CaM affinity) and dantrolene rescue mechanistically unified phosphorylation, CaM regulation, and leak; parallel work defined neuronal RyR2 roles in synapses, cardiac mitochondrial metabolism, and \\u03b2-cell survival.\",\n      \"evidence\": \"S2814D/A knock-in mice, DPc10 conformational and FRET CaM assays; RyR2-R176Q neuronal knock-in; cardiac Ryr2 haploinsufficient mice; \\u03b2-cell calpain-10 apoptosis assays\",\n      \"pmids\": [\"27318036\", \"27482086\", \"27621312\", \"15044459\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the DPc10-accessible state not solved\", \"Extracardiac mechanisms each rest on individual models\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Mapping four Ca2+-dependent CaM-binding domains and showing phosphorylation gates CaM inhibition in human RyR2 resolved how CaM senses Ca2+ and integrates phosphorylation state to control the channel.\",\n      \"evidence\": \"Fluorescence anisotropy of CaMBD peptides; single-channel bilayer and FRET with phosphomimetic knock-in RyR2; systematic study of 14 arrhythmogenic CaM mutations\",\n      \"pmids\": [\"30530841\", \"30928430\", \"31230402\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How phosphorylation alters CaMBD-CaM contacts structurally unresolved\", \"Integration of the four CaMBDs in the intact tetramer not visualized\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"PKA-S2030 control of CaM-dependent inactivation and Ca2+ alternans, an integrin \\u03b21D-RyR2 stabilizing interaction, a mitochondrial ROS feedback loop, RyR2-Cx43 hemichannel coupling, and RyR2 inhibition as flecainide's antiarrhythmic mechanism collectively expanded the regulatory and pharmacological map.\",\n      \"evidence\": \"In vivo CaM-variant delivery and Ca2+ imaging; integrin \\u03b21D bilayer reconstitution and KO mice; genetic ROS/Ca2+ probes with dominant-negative MCU; PLA/co-IP and Ca2+-clamp for Cx43; matched flecainide analogues across bilayer, sodium-channel, and in vivo CPVT assays\",\n      \"pmids\": [\"33375811\", \"32122157\", \"32444920\", \"31841141\", \"33297863\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Spatial relationship between S2030 and S2814 phospho-control not unified\", \"Integrin and Cx43 interaction interfaces not structurally defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identifying loss-of-function mutations causing a CRDS distinct from CPVT, plus neuronal nuclear Ca2+ signaling roles, established the bidirectional disease spectrum and CNS reach of RyR2.\",\n      \"evidence\": \"Bilayer single-channel and SOICR/dominant-negative studies of E4146K/G4935R; pharmacological RyR inhibition with CREB/Npas4 readouts in hippocampal neurons\",\n      \"pmids\": [\"33825858\", \"34389673\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo cardiac phenotype of these LOF mutations not yet shown at this stage\", \"Neuronal nuclear Ca2+ link rests on pharmacology without genetic RyR2 ablation\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defining resting cytosolic activity (Arest) as the determinant of the luminal Ca2+ threshold and correlating it with patient onset age, plus the redox-sensitive ERp44-Cys4806 interaction, provided quantitative and molecular bases for arrhythmogenesis.\",\n      \"evidence\": \"HEK293 cytosolic/ER Ca2+ measurements with kinetic modeling across CPVT mutations; co-IP, C4806 mutagenesis, molecular dynamics, and ROS biosensor for ERp44/Ero1\\u03b1\",\n      \"pmids\": [\"35446340\", \"35086342\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Arest framework derived in HEK293, not native myocytes\", \"Structural docking of ERp44 on the luminal face not resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Genetic RyR2 depletion linking ER stress/ATF4 signaling to cardiomyocyte maturation, and an LOF I4855M knock-in producing LVNC, connected RyR2 channel function to development and structural cardiomyopathy.\",\n      \"evidence\": \"Cas9/AAV9 somatic RYR2 knockout with RNA-Seq/ChIP-Seq and ATF4 manipulation; I4855M knock-in mice with echocardiography and Ca2+ imaging\",\n      \"pmids\": [\"35576474\", \"37325910\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How channel activity is transduced to ATF4/ER stress not mechanistically traced\", \"Developmental versus adult contributions of RyR2 not separated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the regulatory inputs (CaM occupancy, S2814/S2030 phosphorylation, redox modifications, ERp44 and integrin \\u03b21D binding) are spatially integrated within the intact tetramer to set open probability, and how tissue-specific interactomes redirect RyR2 output in neurons, \\u03b2 cells, and T cells, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No unified structural model integrating phospho-, CaM-, and redox-control sites\", \"Extracardiac RyR2 partner complexes not fully reconstituted\", \"Causal link between channel conformational states and downstream transcription/metabolism incompletely mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005262\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005216\", \"supporting_discovery_ids\": [1, 30, 40]},\n      {\"term_id\": \"GO:0005509\", \"supporting_discovery_ids\": [6, 7, 10]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [32, 30]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005790\", \"supporting_discovery_ids\": [19, 18]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [16, 33, 32]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [20, 21, 41]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [18, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 30]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 1, 26, 35]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [38, 34]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [33, 19, 22]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [18, 16]}\n    ],\n    \"complexes\": [\n      \"RyR2-calstabin2 (FKBP12.6) complex\",\n      \"Cav1.3-RyR2-KCa3.1 junctional complex\",\n      \"RyR2-calmodulin complex\"\n    ],\n    \"partners\": [\n      \"CALM1\",\n      \"FKBP12.6\",\n      \"ERp44\",\n      \"ITGB1 (integrin \\u03b21D)\",\n      \"GJA1 (Cx43)\",\n      \"KCNN2 (SK2)\",\n      \"JPH3\",\n      \"IRBIT\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}