{"gene":"CALM3","run_date":"2026-06-09T22:57:17","timeline":{"discoveries":[{"year":2016,"finding":"The CALM3-encoded calmodulin variant E141G reduces Ca2+-binding affinity 11-fold and causes a functionally dominant loss of inactivation in the cardiac L-type calcium channel CaV1.2, mild accentuation of NaV1.5 late current, but no effect on intracellular RyR2-mediated calcium release.","method":"In vitro Ca2+-binding affinity assays, whole-cell patch-clamp of CaV1.2 and NaV1.5, intracellular Ca2+ release measurements in cardiomyocytes","journal":"Circulation. Cardiovascular genetics","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal functional assays (Ca2+-binding, patch-clamp for two channels, RyR2 Ca2+ release) in a single focused study","pmids":["26969752"],"is_preprint":false},{"year":2016,"finding":"The CALM3 variant A103V modestly reduces CaM Ca2+-binding affinity (~3-fold), does not alter CaM binding to RyR2, but promotes spontaneous arrhythmogenic Ca2+ waves and sparks in permeabilized cardiomyocytes via RyR2 dysregulation; even a 1:3 ratio of A103V-CaM:WT-CaM is sufficient to evoke these Ca2+ disturbances, demonstrating functional dominance. A103V has significantly less effect on L-type Ca2+ current inactivation and does not alter action potential duration compared with LQTS-associated CaM variants.","method":"In vitro Ca2+-binding affinity measurement, RyR2-CaM binding assay, Ca2+ handling assays in permeabilized cardiomyocytes, patch-clamp of L-type Ca2+ current, action potential recording in intact cardiomyocytes","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods (Ca2+-binding, RyR2 binding, Ca2+ imaging, patch-clamp, action potential) in a single focused study","pmids":["27516456"],"is_preprint":false},{"year":2022,"finding":"The CALM3 variant N138K reduces Ca2+-binding affinity of the CaM C-terminal domain 10-fold compared with WT-CaM, slows CaV1.2 (ICaL) inactivation, and unexpectedly potentiates IKs (slow delayed rectifier K+ current) density; this combined effect (milder ICaL impairment + IKs augmentation) explains the milder LQTS phenotype compared with previously reported severe de novo CaM variants.","method":"Stoichiometric Ca2+ titrations and equilibrium titrations, whole-cell patch-clamp (ICaL and IKs), optical fluorescence assays for Cav1.2 and Kv7.1 membrane expression","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal methods (Ca2+-binding, patch-clamp for two channels, membrane expression assay) in a single focused study","pmids":["35225649"],"is_preprint":false},{"year":2017,"finding":"The longest isoform of Calm3 mRNA, which contains a retained intron in its 3'-UTR, is localized to neuronal dendrites; Staufen2 (Stau2) binds this retained intron and mediates dendritic localization without affecting mRNA stability. NMDA-mediated synaptic activity specifically promotes dendritic localization of this Calm3 isoform, while inhibition of synaptic activity reduces it.","method":"iCLIP (individual-nucleotide resolution CLIP) for Stau2 binding mapping, fluorescence in situ hybridization/imaging for dendritic mRNA localization, Stau2 knockdown, NMDA stimulation and activity inhibition experiments in neurons","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — iCLIP, loss-of-function (Stau2 KD), pharmacological modulation, multiple orthogonal methods in a single focused study","pmids":["28765142"],"is_preprint":false},{"year":2024,"finding":"A suppression-and-replacement (SupRep) gene therapy construct containing CALM3-specific shRNA (94% knockdown efficiency) plus a shRNA-immune CALM1 cDNA replacement shortens the pathologically prolonged action potential duration (APD90) in CALM3-D130G patient-derived iPSC-derived cardiomyocytes, demonstrating that knocking down mutant CALM3 transcript and replacing with WT calmodulin is sufficient to rescue the electrophysiological phenotype.","method":"shRNA knockdown efficiency assay (RT-qPCR in TSA201 cells), voltage-sensing dye APD90 measurement in patient iPSC-derived cardiomyocytes","journal":"Circulation. Arrhythmia and electrophysiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD + replacement with defined electrophysiological readout in patient-derived cells; single lab, two orthogonal methods","pmids":["39069900"],"is_preprint":false},{"year":1998,"finding":"CALM3 is at least 5-fold more actively transcribed than CALM1 or CALM2 in proliferating human teratoma cells; the 5'-untranslated regions of the CALM genes are necessary to recover full promoter activation in transient transfection reporter assays.","method":"Nuclear run-on transcription assay, mRNA quantification, luciferase reporter transfection assays with CALM gene 5'-flanking sequences including or excluding 5'-UTR","journal":"Cell calcium","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — nuclear run-on and reporter assays in a single lab, two orthogonal methods measuring transcriptional activity","pmids":["9681195"],"is_preprint":false},{"year":2026,"finding":"Ribosome profiling of human left ventricular tissue shows that CALM3 accounts for only ~11% of calmodulin protein produced in the ventricles (vs. ~44.8% for CALM1 and ~44.2% for CALM2), and CALM3 mRNA constitutes ~21.3% of calmodulin-coding mRNA; this lower translational contribution correlates with less negative selection against CALM3 missense variants and a lower frequency of cardiac events in CALM3 variant carriers compared with CALM1 and CALM2 variant carriers.","method":"GTEx RNA-seq data analysis, paired RNA-seq and ribosome profiling of human left ventricle, gnomAD variant analysis, International Calmodulinopathy Registry clinical data","journal":"Europace","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ribosome profiling provides direct translational output measurement; multiple data sources but observational/bioinformatic rather than experimental manipulation","pmids":["41846582"],"is_preprint":false},{"year":1997,"finding":"Screening of the CALM3 gene by PCR-SSCP and RT-PCR in Alzheimer's disease patients detected point mutations only in intronic flanking regions of exons 3 and 4; no structural changes were found in the regions encoding the Ca2+-binding domains of CALM3, and no alterations in CALM3 transcripts were detected in apoE ε4 allele carriers.","method":"PCR-SSCP analysis of genomic DNA, RT-PCR of CALM3 transcripts from patient lymphoblasts","journal":"Neuroscience letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method per assay; negative result establishing that CALM3 coding sequence is not the cause of altered Ca2+ homeostasis in AD lymphoblasts","pmids":["9237482"],"is_preprint":false},{"year":2024,"finding":"Knockdown of CALM3 in human umbilical cord mesenchymal stem cells (hUC-MSCs) partially reversed DMSO/BHA/DMEM-induced upregulation of neuronal differentiation markers (NSE, NeuN, NF-M mRNA), indicating that CALM3 expression facilitates neuronal differentiation of these cells. hsa-miR-543 negatively regulates CALM3 expression and exerts an opposing effect on neuronal differentiation.","method":"siRNA knockdown of CALM3, RT-qPCR for neuronal markers and CALM3 mRNA, western blotting for CALM3 protein, miRNA mimic transfection","journal":"International journal of developmental neuroscience","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, KD with mRNA-level phenotypic readout; limited mechanistic depth, no direct biochemical mechanism for how CALM3 promotes differentiation","pmids":["39444227"],"is_preprint":false}],"current_model":"CALM3 encodes one of three identical calmodulin proteins and contributes approximately 11% of total calmodulin protein in the human left ventricle (the lowest of the three CALM genes due to lower translational efficiency); pathogenic CALM3 missense variants reduce Ca2+-binding affinity and cause gain-of-function dysregulation of cardiac ion channels—slowing CaV1.2 inactivation, accentuating NaV1.5 late current, or activating RyR2-dependent arrhythmogenic Ca2+ release in a dominant fashion—leading to LQTS or CPVT, while in neurons the longest Calm3 mRNA isoform is transported to dendrites via Staufen2 binding to a retained 3'-UTR intron in an activity-dependent manner."},"narrative":{"mechanistic_narrative":"CALM3 encodes one of the calmodulin proteins and functions principally as a Ca2+-sensing regulator of cardiac ion channels, where pathogenic missense variants cause dominant arrhythmogenic disease [PMID:26969752, PMID:35225649]. Disease-associated substitutions reduce the Ca2+-binding affinity of calmodulin—for example E141G lowers affinity ~11-fold and N138K reduces C-terminal domain affinity ~10-fold—and this defect translates into dysregulation of distinct effectors: loss of CaV1.2 (ICaL) inactivation, modest accentuation of NaV1.5 late current, potentiation of the IKs current, or RyR2-dependent spontaneous arrhythmogenic Ca2+ waves [PMID:26969752, PMID:27516456, PMID:35225649]. The pathogenic effect is functionally dominant, as even a 1:3 ratio of mutant A103V-CaM to wild-type CaM is sufficient to provoke Ca2+ disturbances, and these variants underlie long QT syndrome and CPVT-type Ca2+ release phenotypes [PMID:27516456, PMID:35225649]. Suppression of mutant CALM3 transcript with replacement by wild-type calmodulin cDNA rescues the prolonged action potential duration in patient iPSC-derived cardiomyocytes, establishing the mutant transcript as the disease driver [PMID:39069900]. CALM3 is the lowest translational contributor among the three calmodulin genes in the human left ventricle (~11% of calmodulin protein), a low output that correlates with weaker negative selection against its missense variants and milder clinical phenotypes [PMID:41846582]. Beyond the heart, the longest Calm3 mRNA isoform retains a 3'-UTR intron bound by Staufen2, which directs activity-dependent dendritic localization of the transcript without altering its stability [PMID:28765142].","teleology":[{"year":1998,"claim":"Establishing that the three calmodulin genes are differentially regulated, this work showed CALM3 is transcribed at least 5-fold more actively than CALM1 or CALM2 in proliferating cells and identified the 5'-UTR as required for full promoter activity.","evidence":"Nuclear run-on transcription assay and luciferase reporter transfections with CALM gene 5'-flanking sequences in human teratoma cells","pmids":["9681195"],"confidence":"Medium","gaps":["Transcriptional behavior in non-proliferating or cardiac tissue not addressed","Does not link transcription rate to functional protein output"]},{"year":2016,"claim":"Linking CALM3 missense variants to a defined molecular lesion, these studies demonstrated that pathogenic substitutions reduce calmodulin Ca2+-binding affinity and dysregulate cardiac channels in a dominant fashion, distinguishing channel-specific mechanisms (CaV1.2/NaV1.5 vs RyR2).","evidence":"In vitro Ca2+-binding assays, whole-cell patch-clamp of CaV1.2/NaV1.5/ICaL, RyR2 binding and Ca2+-wave imaging in permeabilized cardiomyocytes","pmids":["26969752","27516456"],"confidence":"High","gaps":["In vivo arrhythmia phenotype not established","Structural basis of effector selectivity not resolved","Why affinity loss maps to distinct channels for different variants unexplained"]},{"year":2017,"claim":"Revealing a non-cardiac role for Calm3 RNA, this work showed an intron-retaining 3'-UTR isoform is delivered to dendrites by Staufen2 in an activity-dependent manner, implicating CALM3 in localized neuronal mRNA transport.","evidence":"Stau2 iCLIP, FISH dendritic localization imaging, Stau2 knockdown, and NMDA stimulation in neurons","pmids":["28765142"],"confidence":"High","gaps":["Local translation of the dendritic isoform not demonstrated","Functional consequence for synaptic calmodulin signaling unknown"]},{"year":2022,"claim":"Explaining phenotypic variability, the N138K variant was shown to combine milder ICaL impairment with unexpected IKs potentiation, accounting for a milder LQTS presentation than severe de novo CaM variants.","evidence":"Stoichiometric Ca2+ titrations, patch-clamp of ICaL and IKs, and membrane-expression fluorescence assays for CaV1.2 and Kv7.1","pmids":["35225649"],"confidence":"High","gaps":["Mechanism of IKs potentiation by mutant CaM not defined","Clinical penetrance link is correlative"]},{"year":2024,"claim":"Demonstrating therapeutic tractability and confirming the mutant transcript as the causal driver, a suppression-and-replacement construct knocking down CALM3 and replacing it with WT calmodulin rescued the action potential phenotype in patient cardiomyocytes.","evidence":"CALM3-specific shRNA knockdown plus shRNA-immune CALM1 cDNA, APD90 voltage-dye measurement in CALM3-D130G patient iPSC-derived cardiomyocytes","pmids":["39069900"],"confidence":"Medium","gaps":["Single patient genotype tested","In vivo efficacy and safety not established","Long-term durability unknown"]},{"year":2024,"claim":"Extending CALM3 function to development, knockdown studies indicated CALM3 facilitates neuronal differentiation of mesenchymal stem cells and is negatively regulated by miR-543.","evidence":"siRNA knockdown of CALM3, RT-qPCR and western blot of neuronal markers, and miRNA mimic transfection in hUC-MSCs","pmids":["39444227"],"confidence":"Low","gaps":["Single lab with mRNA-level readout and no direct biochemical mechanism","Effect is partial reversal only","Relevance to physiological neurogenesis unclear"]},{"year":2026,"claim":"Quantifying CALM3's contribution, ribosome profiling established that CALM3 produces only ~11% of ventricular calmodulin protein, providing a translational basis for the weaker selection against and milder phenotype of CALM3 variants.","evidence":"Paired RNA-seq and ribosome profiling of human left ventricle, gnomAD selection analysis, and International Calmodulinopathy Registry clinical data","pmids":["41846582"],"confidence":"Medium","gaps":["Observational/bioinformatic rather than experimental","Causal link between low translation and mild phenotype is inferential"]},{"year":null,"claim":"How a single calmodulin variant selectively dysregulates one channel versus another, and the structural and recruitment basis for effector specificity, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model linking affinity loss to specific channel targeting","In vivo cardiac consequences of CALM3 variants not modeled","Physiological role of dendritic CALM3 isoform unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[0,2]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-397014","term_label":"Muscle contraction","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1,2]}],"complexes":[],"partners":["CACNA1C","SCN5A","RYR2","KCNQ1","STAU2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P0DP25","full_name":"Calmodulin-3","aliases":[],"length_aa":149,"mass_kda":16.8,"function":"Calmodulin acts as part of a calcium signal transduction pathway by mediating the control of a large number of enzymes, ion channels, aquaporins and other proteins through calcium-binding (PubMed:16760425, PubMed:31454269). Calcium-binding is required for the activation of calmodulin (PubMed:16760425, PubMed:31454269, PubMed:35568036). Among the enzymes to be stimulated by the calmodulin-calcium complex are a number of protein kinases, such as myosin light-chain kinases and calmodulin-dependent protein kinase type II (CaMK2), and phosphatases (PubMed:16760425, PubMed:35568036). Together with CCP110 and centrin, is involved in a genetic pathway that regulates the centrosome cycle and progression through cytokinesis (PubMed:16760425) (Microbial infection) Required for C.violaceum CopC and S.flexneri OspC3 arginine ADP-riboxanase activity","subcellular_location":"Cytoplasm, cytoskeleton, spindle; Cytoplasm, cytoskeleton, spindle pole; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/P0DP25/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CALM3","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000160014","cell_line_id":"CID000513","localizations":[{"compartment":"centrosome","grade":3},{"compartment":"membrane","grade":3},{"compartment":"cytoplasmic","grade":2},{"compartment":"nucleoplasm","grade":2}],"interactors":[{"gene":"CALM2;CALM3;CALM1","stoichiometry":10.0},{"gene":"MYL6","stoichiometry":10.0},{"gene":"UNNAMED","stoichiometry":0.2},{"gene":"FLNB","stoichiometry":0.2},{"gene":"WFS1","stoichiometry":0.2},{"gene":"SCO1","stoichiometry":0.2},{"gene":"KIF1B","stoichiometry":0.2},{"gene":"KIF1C","stoichiometry":0.2},{"gene":"TOM1","stoichiometry":0.2},{"gene":"MYL1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000513","total_profiled":1310},"omim":[{"mim_id":"618782","title":"LONG QT SYNDROME 16; LQT16","url":"https://www.omim.org/entry/618782"},{"mim_id":"616249","title":"LONG QT SYNDROME 15; LQT15","url":"https://www.omim.org/entry/616249"},{"mim_id":"616247","title":"LONG QT SYNDROME 14; LQT14","url":"https://www.omim.org/entry/616247"},{"mim_id":"604772","title":"VENTRICULAR TACHYCARDIA, CATECHOLAMINERGIC POLYMORPHIC, 1, WITH OR WITHOUT ATRIAL DYSFUNCTION AND/OR DILATED CARDIOMYOPATHY; CPVT1","url":"https://www.omim.org/entry/604772"},{"mim_id":"601146","title":"GROWTH/DIFFERENTIATION FACTOR 5; GDF5","url":"https://www.omim.org/entry/601146"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":1443.6}],"url":"https://www.proteinatlas.org/search/CALM3"},"hgnc":{"alias_symbol":["PHKD","PHKD3"],"prev_symbol":[]},"alphafold":{"accession":"P0DP25","domains":[{"cath_id":"1.10.238.10","chopping":"1-78","consensus_level":"high","plddt":83.4788,"start":1,"end":78},{"cath_id":"1.10.238.10","chopping":"94-146","consensus_level":"high","plddt":91.1945,"start":94,"end":146}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P0DP25","model_url":"https://alphafold.ebi.ac.uk/files/AF-P0DP25-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P0DP25-F1-predicted_aligned_error_v6.png","plddt_mean":85.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CALM3","jax_strain_url":"https://www.jax.org/strain/search?query=CALM3"},"sequence":{"accession":"P0DP25","fasta_url":"https://rest.uniprot.org/uniprotkb/P0DP25.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P0DP25/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P0DP25"}},"corpus_meta":[{"pmid":"26969752","id":"PMC_26969752","title":"Spectrum and Prevalence of CALM1-, CALM2-, and CALM3-Encoded Calmodulin Variants in Long QT Syndrome and Functional Characterization of a Novel Long QT Syndrome-Associated Calmodulin Missense Variant, E141G.","date":"2016","source":"Circulation. Cardiovascular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26969752","citation_count":110,"is_preprint":false},{"pmid":"8314583","id":"PMC_8314583","title":"Localization of the human bona fide calmodulin genes CALM1, CALM2, and CALM3 to chromosomes 14q24-q31, 2p21.1-p21.3, and 19q13.2-q13.3.","date":"1993","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/8314583","citation_count":80,"is_preprint":false},{"pmid":"27516456","id":"PMC_27516456","title":"Novel CPVT-Associated Calmodulin Mutation in CALM3 (CALM3-A103V) Activates Arrhythmogenic Ca Waves and Sparks.","date":"2016","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/27516456","citation_count":71,"is_preprint":false},{"pmid":"9681195","id":"PMC_9681195","title":"Characterization of the human CALM2 calmodulin gene and comparison of the transcriptional activity of CALM1, CALM2 and CALM3.","date":"1998","source":"Cell calcium","url":"https://pubmed.ncbi.nlm.nih.gov/9681195","citation_count":62,"is_preprint":false},{"pmid":"28765142","id":"PMC_28765142","title":"A retained intron in the 3'-UTR of Calm3 mRNA mediates its Staufen2- and activity-dependent localization to neuronal dendrites.","date":"2017","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/28765142","citation_count":61,"is_preprint":false},{"pmid":"25089838","id":"PMC_25089838","title":"The novel regulations of MEF2A, CAMKK2, CALM3, and TNNI3 in ventricular hypertrophy induced by arsenic exposure in rats.","date":"2014","source":"Toxicology","url":"https://pubmed.ncbi.nlm.nih.gov/25089838","citation_count":27,"is_preprint":false},{"pmid":"35225649","id":"PMC_35225649","title":"Novel CALM3 Variant Causing Calmodulinopathy With Variable Expressivity in a 4-Generation Family.","date":"2022","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/35225649","citation_count":21,"is_preprint":false},{"pmid":"28744816","id":"PMC_28744816","title":"ACE2, CALM3 and TNNI3K polymorphisms as potential disease modifiers in hypertrophic and dilated cardiomyopathies.","date":"2017","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28744816","citation_count":19,"is_preprint":false},{"pmid":"39069900","id":"PMC_39069900","title":"Single Construct Suppression and Replacement Gene Therapy for the Treatment of All CALM1-, CALM2-, and CALM3-Mediated Arrhythmia Disorders.","date":"2024","source":"Circulation. Arrhythmia and electrophysiology","url":"https://pubmed.ncbi.nlm.nih.gov/39069900","citation_count":12,"is_preprint":false},{"pmid":"9237482","id":"PMC_9237482","title":"Mutation analysis of chromosome 19 calmodulin (CALM3) gene in Alzheimer's disease patients.","date":"1997","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/9237482","citation_count":7,"is_preprint":false},{"pmid":"33214751","id":"PMC_33214751","title":"Molecular docking studies of a-mangostin with oral cancer targets ARRB1, FLNA, CALM3 and HTT.","date":"2020","source":"Bioinformation","url":"https://pubmed.ncbi.nlm.nih.gov/33214751","citation_count":4,"is_preprint":false},{"pmid":"25396734","id":"PMC_25396734","title":"Comprehensive analysis of the association of EGFR, CALM3 and SMARCD1 gene polymorphisms with BMD in Caucasian women.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25396734","citation_count":2,"is_preprint":false},{"pmid":"30488312","id":"PMC_30488312","title":"Correction to: ACE2, CALM3 and TNNI3K polymorphisms as potential disease modifiers in hypertrophic and dilated cardiomyopathies.","date":"2019","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30488312","citation_count":1,"is_preprint":false},{"pmid":"39444227","id":"PMC_39444227","title":"Role of hsa-miR-543-KIF5C/CALM3 pathway in neuron differentiation of embryonic mesenchymal stem cells.","date":"2024","source":"International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/39444227","citation_count":0,"is_preprint":false},{"pmid":"41846582","id":"PMC_41846582","title":"CALM1, CALM2, and CALM3 expression and translation efficiency provide insight into the severity of calmodulinopathy.","date":"2026","source":"Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/41846582","citation_count":0,"is_preprint":false},{"pmid":"42238753","id":"PMC_42238753","title":"Flaxseed (Linum usitatissimum) Modulates Oxytocin Signaling Pathway via CALM3-mediated Calcium Signaling: A Protein-protein Interaction Network and Functional Enrichment Analysis.","date":"2025","source":"Basic and clinical neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/42238753","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10920,"output_tokens":2735,"usd":0.036893,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9984,"output_tokens":2942,"usd":0.061735,"stage2_stop_reason":"end_turn"},"total_usd":0.098628,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2016,\n      \"finding\": \"The CALM3-encoded calmodulin variant E141G reduces Ca2+-binding affinity 11-fold and causes a functionally dominant loss of inactivation in the cardiac L-type calcium channel CaV1.2, mild accentuation of NaV1.5 late current, but no effect on intracellular RyR2-mediated calcium release.\",\n      \"method\": \"In vitro Ca2+-binding affinity assays, whole-cell patch-clamp of CaV1.2 and NaV1.5, intracellular Ca2+ release measurements in cardiomyocytes\",\n      \"journal\": \"Circulation. Cardiovascular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal functional assays (Ca2+-binding, patch-clamp for two channels, RyR2 Ca2+ release) in a single focused study\",\n      \"pmids\": [\"26969752\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The CALM3 variant A103V modestly reduces CaM Ca2+-binding affinity (~3-fold), does not alter CaM binding to RyR2, but promotes spontaneous arrhythmogenic Ca2+ waves and sparks in permeabilized cardiomyocytes via RyR2 dysregulation; even a 1:3 ratio of A103V-CaM:WT-CaM is sufficient to evoke these Ca2+ disturbances, demonstrating functional dominance. A103V has significantly less effect on L-type Ca2+ current inactivation and does not alter action potential duration compared with LQTS-associated CaM variants.\",\n      \"method\": \"In vitro Ca2+-binding affinity measurement, RyR2-CaM binding assay, Ca2+ handling assays in permeabilized cardiomyocytes, patch-clamp of L-type Ca2+ current, action potential recording in intact cardiomyocytes\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods (Ca2+-binding, RyR2 binding, Ca2+ imaging, patch-clamp, action potential) in a single focused study\",\n      \"pmids\": [\"27516456\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The CALM3 variant N138K reduces Ca2+-binding affinity of the CaM C-terminal domain 10-fold compared with WT-CaM, slows CaV1.2 (ICaL) inactivation, and unexpectedly potentiates IKs (slow delayed rectifier K+ current) density; this combined effect (milder ICaL impairment + IKs augmentation) explains the milder LQTS phenotype compared with previously reported severe de novo CaM variants.\",\n      \"method\": \"Stoichiometric Ca2+ titrations and equilibrium titrations, whole-cell patch-clamp (ICaL and IKs), optical fluorescence assays for Cav1.2 and Kv7.1 membrane expression\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal methods (Ca2+-binding, patch-clamp for two channels, membrane expression assay) in a single focused study\",\n      \"pmids\": [\"35225649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"The longest isoform of Calm3 mRNA, which contains a retained intron in its 3'-UTR, is localized to neuronal dendrites; Staufen2 (Stau2) binds this retained intron and mediates dendritic localization without affecting mRNA stability. NMDA-mediated synaptic activity specifically promotes dendritic localization of this Calm3 isoform, while inhibition of synaptic activity reduces it.\",\n      \"method\": \"iCLIP (individual-nucleotide resolution CLIP) for Stau2 binding mapping, fluorescence in situ hybridization/imaging for dendritic mRNA localization, Stau2 knockdown, NMDA stimulation and activity inhibition experiments in neurons\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — iCLIP, loss-of-function (Stau2 KD), pharmacological modulation, multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"28765142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A suppression-and-replacement (SupRep) gene therapy construct containing CALM3-specific shRNA (94% knockdown efficiency) plus a shRNA-immune CALM1 cDNA replacement shortens the pathologically prolonged action potential duration (APD90) in CALM3-D130G patient-derived iPSC-derived cardiomyocytes, demonstrating that knocking down mutant CALM3 transcript and replacing with WT calmodulin is sufficient to rescue the electrophysiological phenotype.\",\n      \"method\": \"shRNA knockdown efficiency assay (RT-qPCR in TSA201 cells), voltage-sensing dye APD90 measurement in patient iPSC-derived cardiomyocytes\",\n      \"journal\": \"Circulation. Arrhythmia and electrophysiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD + replacement with defined electrophysiological readout in patient-derived cells; single lab, two orthogonal methods\",\n      \"pmids\": [\"39069900\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CALM3 is at least 5-fold more actively transcribed than CALM1 or CALM2 in proliferating human teratoma cells; the 5'-untranslated regions of the CALM genes are necessary to recover full promoter activation in transient transfection reporter assays.\",\n      \"method\": \"Nuclear run-on transcription assay, mRNA quantification, luciferase reporter transfection assays with CALM gene 5'-flanking sequences including or excluding 5'-UTR\",\n      \"journal\": \"Cell calcium\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — nuclear run-on and reporter assays in a single lab, two orthogonal methods measuring transcriptional activity\",\n      \"pmids\": [\"9681195\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Ribosome profiling of human left ventricular tissue shows that CALM3 accounts for only ~11% of calmodulin protein produced in the ventricles (vs. ~44.8% for CALM1 and ~44.2% for CALM2), and CALM3 mRNA constitutes ~21.3% of calmodulin-coding mRNA; this lower translational contribution correlates with less negative selection against CALM3 missense variants and a lower frequency of cardiac events in CALM3 variant carriers compared with CALM1 and CALM2 variant carriers.\",\n      \"method\": \"GTEx RNA-seq data analysis, paired RNA-seq and ribosome profiling of human left ventricle, gnomAD variant analysis, International Calmodulinopathy Registry clinical data\",\n      \"journal\": \"Europace\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ribosome profiling provides direct translational output measurement; multiple data sources but observational/bioinformatic rather than experimental manipulation\",\n      \"pmids\": [\"41846582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Screening of the CALM3 gene by PCR-SSCP and RT-PCR in Alzheimer's disease patients detected point mutations only in intronic flanking regions of exons 3 and 4; no structural changes were found in the regions encoding the Ca2+-binding domains of CALM3, and no alterations in CALM3 transcripts were detected in apoE ε4 allele carriers.\",\n      \"method\": \"PCR-SSCP analysis of genomic DNA, RT-PCR of CALM3 transcripts from patient lymphoblasts\",\n      \"journal\": \"Neuroscience letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method per assay; negative result establishing that CALM3 coding sequence is not the cause of altered Ca2+ homeostasis in AD lymphoblasts\",\n      \"pmids\": [\"9237482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Knockdown of CALM3 in human umbilical cord mesenchymal stem cells (hUC-MSCs) partially reversed DMSO/BHA/DMEM-induced upregulation of neuronal differentiation markers (NSE, NeuN, NF-M mRNA), indicating that CALM3 expression facilitates neuronal differentiation of these cells. hsa-miR-543 negatively regulates CALM3 expression and exerts an opposing effect on neuronal differentiation.\",\n      \"method\": \"siRNA knockdown of CALM3, RT-qPCR for neuronal markers and CALM3 mRNA, western blotting for CALM3 protein, miRNA mimic transfection\",\n      \"journal\": \"International journal of developmental neuroscience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, KD with mRNA-level phenotypic readout; limited mechanistic depth, no direct biochemical mechanism for how CALM3 promotes differentiation\",\n      \"pmids\": [\"39444227\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CALM3 encodes one of three identical calmodulin proteins and contributes approximately 11% of total calmodulin protein in the human left ventricle (the lowest of the three CALM genes due to lower translational efficiency); pathogenic CALM3 missense variants reduce Ca2+-binding affinity and cause gain-of-function dysregulation of cardiac ion channels—slowing CaV1.2 inactivation, accentuating NaV1.5 late current, or activating RyR2-dependent arrhythmogenic Ca2+ release in a dominant fashion—leading to LQTS or CPVT, while in neurons the longest Calm3 mRNA isoform is transported to dendrites via Staufen2 binding to a retained 3'-UTR intron in an activity-dependent manner.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CALM3 encodes one of the calmodulin proteins and functions principally as a Ca2+-sensing regulator of cardiac ion channels, where pathogenic missense variants cause dominant arrhythmogenic disease [#0, #2]. Disease-associated substitutions reduce the Ca2+-binding affinity of calmodulin\\u2014for example E141G lowers affinity ~11-fold and N138K reduces C-terminal domain affinity ~10-fold\\u2014and this defect translates into dysregulation of distinct effectors: loss of CaV1.2 (ICaL) inactivation, modest accentuation of NaV1.5 late current, potentiation of the IKs current, or RyR2-dependent spontaneous arrhythmogenic Ca2+ waves [#0, #1, #2]. The pathogenic effect is functionally dominant, as even a 1:3 ratio of mutant A103V-CaM to wild-type CaM is sufficient to provoke Ca2+ disturbances, and these variants underlie long QT syndrome and CPVT-type Ca2+ release phenotypes [#1, #2]. Suppression of mutant CALM3 transcript with replacement by wild-type calmodulin cDNA rescues the prolonged action potential duration in patient iPSC-derived cardiomyocytes, establishing the mutant transcript as the disease driver [#4]. CALM3 is the lowest translational contributor among the three calmodulin genes in the human left ventricle (~11% of calmodulin protein), a low output that correlates with weaker negative selection against its missense variants and milder clinical phenotypes [#6]. Beyond the heart, the longest Calm3 mRNA isoform retains a 3'-UTR intron bound by Staufen2, which directs activity-dependent dendritic localization of the transcript without altering its stability [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Establishing that the three calmodulin genes are differentially regulated, this work showed CALM3 is transcribed at least 5-fold more actively than CALM1 or CALM2 in proliferating cells and identified the 5'-UTR as required for full promoter activity.\",\n      \"evidence\": \"Nuclear run-on transcription assay and luciferase reporter transfections with CALM gene 5'-flanking sequences in human teratoma cells\",\n      \"pmids\": [\"9681195\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcriptional behavior in non-proliferating or cardiac tissue not addressed\", \"Does not link transcription rate to functional protein output\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linking CALM3 missense variants to a defined molecular lesion, these studies demonstrated that pathogenic substitutions reduce calmodulin Ca2+-binding affinity and dysregulate cardiac channels in a dominant fashion, distinguishing channel-specific mechanisms (CaV1.2/NaV1.5 vs RyR2).\",\n      \"evidence\": \"In vitro Ca2+-binding assays, whole-cell patch-clamp of CaV1.2/NaV1.5/ICaL, RyR2 binding and Ca2+-wave imaging in permeabilized cardiomyocytes\",\n      \"pmids\": [\"26969752\", \"27516456\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo arrhythmia phenotype not established\", \"Structural basis of effector selectivity not resolved\", \"Why affinity loss maps to distinct channels for different variants unexplained\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Revealing a non-cardiac role for Calm3 RNA, this work showed an intron-retaining 3'-UTR isoform is delivered to dendrites by Staufen2 in an activity-dependent manner, implicating CALM3 in localized neuronal mRNA transport.\",\n      \"evidence\": \"Stau2 iCLIP, FISH dendritic localization imaging, Stau2 knockdown, and NMDA stimulation in neurons\",\n      \"pmids\": [\"28765142\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Local translation of the dendritic isoform not demonstrated\", \"Functional consequence for synaptic calmodulin signaling unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Explaining phenotypic variability, the N138K variant was shown to combine milder ICaL impairment with unexpected IKs potentiation, accounting for a milder LQTS presentation than severe de novo CaM variants.\",\n      \"evidence\": \"Stoichiometric Ca2+ titrations, patch-clamp of ICaL and IKs, and membrane-expression fluorescence assays for CaV1.2 and Kv7.1\",\n      \"pmids\": [\"35225649\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of IKs potentiation by mutant CaM not defined\", \"Clinical penetrance link is correlative\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrating therapeutic tractability and confirming the mutant transcript as the causal driver, a suppression-and-replacement construct knocking down CALM3 and replacing it with WT calmodulin rescued the action potential phenotype in patient cardiomyocytes.\",\n      \"evidence\": \"CALM3-specific shRNA knockdown plus shRNA-immune CALM1 cDNA, APD90 voltage-dye measurement in CALM3-D130G patient iPSC-derived cardiomyocytes\",\n      \"pmids\": [\"39069900\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single patient genotype tested\", \"In vivo efficacy and safety not established\", \"Long-term durability unknown\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extending CALM3 function to development, knockdown studies indicated CALM3 facilitates neuronal differentiation of mesenchymal stem cells and is negatively regulated by miR-543.\",\n      \"evidence\": \"siRNA knockdown of CALM3, RT-qPCR and western blot of neuronal markers, and miRNA mimic transfection in hUC-MSCs\",\n      \"pmids\": [\"39444227\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single lab with mRNA-level readout and no direct biochemical mechanism\", \"Effect is partial reversal only\", \"Relevance to physiological neurogenesis unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Quantifying CALM3's contribution, ribosome profiling established that CALM3 produces only ~11% of ventricular calmodulin protein, providing a translational basis for the weaker selection against and milder phenotype of CALM3 variants.\",\n      \"evidence\": \"Paired RNA-seq and ribosome profiling of human left ventricle, gnomAD selection analysis, and International Calmodulinopathy Registry clinical data\",\n      \"pmids\": [\"41846582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Observational/bioinformatic rather than experimental\", \"Causal link between low translation and mild phenotype is inferential\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single calmodulin variant selectively dysregulates one channel versus another, and the structural and recruitment basis for effector specificity, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model linking affinity loss to specific channel targeting\", \"In vivo cardiac consequences of CALM3 variants not modeled\", \"Physiological role of dendritic CALM3 isoform unestablished\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-397014\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CACNA1C\", \"SCN5A\", \"RYR2\", \"KCNQ1\", \"STAU2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}