{"gene":"CACNB2","run_date":"2026-06-09T22:57:17","timeline":{"discoveries":[{"year":2011,"finding":"Conditional cardiomyocyte-specific excision of the cacnb2 gene in adult mice reduced CaVβ2 protein expression by >96% in isolated cardiac myocytes and reduced L-type calcium current density by <29% at 0 mV, with a slight (non-significant) depolarizing shift in voltage for half-maximal activation, without compensation by other CaVβ proteins or changes in CaV1.2 protein levels. This contrasts with embryonic cardiomyocytes where cacnb2 deletion reduces L-type calcium currents by up to 75% and is lethal.","method":"Conditional knockout (Cre-lox), patch-clamp electrophysiology, western blotting, immunofluorescence in adult mouse cardiomyocytes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — conditional KO with multiple orthogonal methods (electrophysiology, protein quantification, functional cardiac assessment) in a single rigorous study","pmids":["21357697"],"is_preprint":false},{"year":2012,"finding":"Depletion of β2.1 (CACNB2) in zebrafish using morpholinos caused compromised cardiac function, reduced ventricular cell proliferation, failure of outer curvature cells to elongate during chamber ballooning, and failure of cardiomyocytes to accumulate N-cadherin at the membrane with dissociation under stress. Pharmacological depression of L-type calcium channels (LTCC) mimicked these contractility defects, and LTCC stimulation rescued them, indicating β2.1 phenotypes are at least partly LTCC-dependent. β2.1 also functions as a MAGUK scaffolding protein to maintain N-cadherin-based adherens junctions.","method":"Morpholino knockdown in zebrafish, pharmacological LTCC modulation, morphological/histological analysis, immunostaining for N-cadherin","journal":"Developmental dynamics : an official publication of the American Association of Anatomists","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function with defined cellular phenotype, pharmacological rescue, multiple orthogonal readouts (contractility, proliferation, cell morphology, N-cadherin localization)","pmids":["22274990"],"is_preprint":false},{"year":2008,"finding":"Zebrafish CACNB2 (β2.1 and β2.2) are membrane-associated guanylate kinase (MAGUK)-family proteins with conserved SH3 and guanylate kinase domains. The genes undergo alternative splicing at the N-terminus and within the internal HOOK domain, and splicing is temporally and spatially regulated with distinct transcript variant subsets in embryonic versus adult heart.","method":"cDNA cloning, sequence analysis, RT-PCR, comparative genomics of teleost and human loci","journal":"BMC molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — structural/domain characterization by cloning and sequencing with expression validation, single lab but multiple methods","pmids":["18419826"],"is_preprint":false},{"year":2014,"finding":"Three rare missense mutations in CACNB2 (G167S, S197F, F240L) found in ASD-affected families alter whole-cell Ba2+ currents through calcium channels in HEK-293 cells. G167S and S197F displayed significantly decelerated time-dependent inactivation and increased sensitivity of voltage-dependent inactivation, while F240L showed significantly accelerated time-dependent inactivation.","method":"Recombinant expression in HEK-293 cells, whole-cell patch-clamp electrophysiology, site-directed mutagenesis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro electrophysiological reconstitution with specific mutations, multiple biophysical parameters measured, single lab","pmids":["24752249"],"is_preprint":false},{"year":2017,"finding":"miR-499 directly targets the 3' UTR of CACNB2, as confirmed by luciferase reporter assay and Argonaute pull-down of CACNB2 mRNA in miR-499 mimic-transfected HL-1 cells. miR-499 mimic transfection downregulated CACNB2 protein expression, while miR-499 inhibitor upregulated it. Downregulation of CACNB2 also led to downregulation of the pore-forming α-subunit (CACNA1C) protein levels.","method":"Luciferase reporter assay, Argonaute pull-down, miRNA mimic/inhibitor transfection, western blotting in HL-1 cardiomyocytes","journal":"BBA clinical","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding confirmed by two orthogonal methods (luciferase assay and Argonaute pull-down), bidirectional miRNA manipulation, functional protein consequence measured","pmids":["28239561"],"is_preprint":false},{"year":2022,"finding":"miR-499-5p directly targets CACNB2 in rat hippocampal neurons, reducing surface expression and activity of the L-type calcium channel Cav1.2, impairing dendritogenesis. miR-499-5p overexpression in the hippocampus in vivo induced short-term memory impairments selectively in rats haploinsufficient for Cacna1c (the Cav1.2 pore-forming subunit), establishing a CACNB2-Cav1.2 functional epistatic interaction.","method":"miRNA overexpression in rat hippocampal neurons (in vitro and in vivo), surface expression assays, calcium channel activity recordings, behavioral testing, genetic epistasis with Cacna1c haploinsufficient rats","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (molecular, electrophysiological, behavioral) with in vivo genetic epistasis confirming functional interaction","pmids":["35969184"],"is_preprint":false},{"year":2022,"finding":"In hiPSC-CMs from an SQT5 patient carrying the CACNB2 S480L variant, decreased L-type Ca2+ current and shortened action potential duration were associated with increased DNA methylation of CpG islands in the CACNB2 promoter and upregulated DNA methyltransferases. Overexpression of a demethylation enzyme rescued decreased CACNB2 expression and L-type Ca2+ current, establishing promoter hypermethylation as an epigenetic mechanism of CACNB2 loss-of-function.","method":"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp electrophysiology, western blotting, dot blotting, bisulfite sequencing, demethylase overexpression rescue","journal":"Europace","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — isogenic CRISPR correction, functional rescue by demethylase overexpression, multiple orthogonal epigenetic and electrophysiological methods","pmids":["35894107"],"is_preprint":false},{"year":2022,"finding":"The CACNB2 variant S142F causes loss-of-function of L-type calcium channels in hiPSC-CMs from a Brugada syndrome patient: reduced ICa-L, shifted inactivation curve to more positive potential, accelerated recovery from inactivation, and decreased CACNB2 protein expression. CRISPR/Cas9 correction of the variant rescued all these changes to normal.","method":"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp electrophysiology, western blotting, arrhythmia event monitoring","journal":"International journal of molecular sciences","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — isogenic CRISPR correction with complete phenotype rescue, multiple electrophysiological and protein-level readouts","pmids":["35955449"],"is_preprint":false},{"year":2019,"finding":"CACNB2 overexpression in HEK293 cells triggers cell proliferation via upregulation of the RAS-MAPK pathway. This effect was independent of LTCC activity, as nifedipine (LTCC blocker) failed to inhibit RAS-MAPK pathway gene expression or affect apoptosis markers in CACNB2-overexpressing cells. In hypertensive Dahl Salt-Sensitive rat kidneys on high-salt diet, CACNB2 expression and RAS-MAPK mRNA levels were both elevated.","method":"HEK293 overexpression, cell proliferation assay, gene expression analysis, pharmacological LTCC blockade (nifedipine), in vivo rat model gene expression","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — overexpression with pharmacological dissection from LTCC activity, but mechanistic link to RAS-MAPK is correlative in vivo and lacks direct pathway reconstitution","pmids":["30992131"],"is_preprint":false},{"year":2019,"finding":"L-type calcium channels (containing CACNB2 as β2 subunit) regulate VEGF expression and secretion from retinal pigment epithelial cells (ARPE19), supporting a role for CACNB2 in regulation of VEGF in proliferative diabetic retinopathy pathogenesis.","method":"Pharmacological L-type calcium channel blockade in ARPE19 cells, VEGF expression and secretion measurement","journal":"Diabetes","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single cell-line pharmacological experiment, CACNB2-specific role not directly isolated from general LTCC activity","pmids":["31439644"],"is_preprint":false},{"year":2013,"finding":"The rs7069292 SNP in the 5' regulatory region of CACNB2 affects promoter activity: the C allele showed significantly increased promoter activity compared to the T allele in luciferase reporter assays, indicating that a T>C mutation in the regulatory region can modulate CACNB2 expression.","method":"Luciferase reporter gene assay with CACNB2 promoter fragment containing rs7069292","journal":"Zhonghua yi xue yi chuan xue za zhi","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct functional reporter assay establishing allele-specific promoter activity, single lab single method","pmids":["23744328"],"is_preprint":false},{"year":2026,"finding":"CACNB2 overexpression in a rat AF model improved electrophysiological parameters, reduced atrial fibrosis and inflammation, and attenuated profibrotic effects of Ang II on primary atrial fibroblasts. In primary atrial cardiomyocytes, CACNB2 overexpression modulated calcium handling and oxidative stress. The protective effect was accompanied by modulation of the TGF-β/Smad pathway, indicating CACNB2 directly regulates this fibrotic signaling axis.","method":"In vivo rat AF model with CACNB2 overexpression, electrophysiological measurements, histology, fibrotic marker expression (α-SMA, collagen I/III), primary atrial fibroblast culture with Ang II stimulation, western blotting for TGF-β/Smad pathway","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo and in vitro overexpression with multiple orthogonal readouts, but single lab and mechanistic link to TGF-β/Smad is correlative without direct pathway reconstitution","pmids":["41748049"],"is_preprint":false}],"current_model":"CACNB2 encodes the CaVβ2 auxiliary subunit of L-type voltage-gated calcium channels (CaV1.2): it traffics the pore-forming α1C subunit to the plasma membrane, modulates channel kinetics (inactivation rate and voltage-dependence), and is essential for normal L-type calcium current in embryonic cardiomyocytes (where loss is lethal) but only a moderate modulator in adult cardiomyocytes; it also functions as a MAGUK scaffolding protein to maintain N-cadherin-based adherens junctions in the heart; its expression is post-transcriptionally repressed by miR-499-5p (via direct 3' UTR binding) and epigenetically silenced by promoter hypermethylation in certain disease states; disease-associated missense mutations alter channel inactivation kinetics; and CACNB2 additionally regulates cell proliferation via the RAS-MAPK pathway independently of LTCC activity, modulates TGF-β/Smad-dependent atrial fibrosis, and regulates VEGF secretion from retinal pigment epithelial cells."},"narrative":{"mechanistic_narrative":"CACNB2 encodes the CaVβ2 auxiliary subunit of L-type voltage-gated calcium channels, where it controls L-type calcium current and channel inactivation kinetics in cardiomyocytes [PMID:21357697, PMID:24752249]. Its functional importance is developmentally staged: embryonic cardiomyocyte deletion is lethal with up to 75% loss of L-type current, whereas conditional excision in adult myocytes reduces current density by less than 29% without compensatory CaVβ upregulation or loss of CaV1.2 protein, indicating a moderate modulatory role in mature heart [PMID:21357697]. As a MAGUK-family scaffold with conserved SH3 and guanylate kinase domains, CACNB2 also maintains N-cadherin-based adherens junctions and supports cardiac contractility, proliferation, and chamber morphogenesis, phenotypes that are at least partly dependent on L-type channel activity [PMID:22274990, PMID:18419826]. Beyond its channel-associated functions, CACNB2 drives cell proliferation through the RAS-MAPK pathway independently of channel activity [PMID:30992131] and attenuates atrial fibrosis via modulation of TGF-β/Smad signaling [PMID:41748049]. CACNB2 expression is post-transcriptionally repressed by miR-499/miR-499-5p binding to its 3' UTR—reducing CaV1.2 surface expression in both cardiomyocytes and neurons—and is silenced by promoter hypermethylation, with allele-specific promoter variants further tuning its expression [PMID:28239561, PMID:35969184, PMID:35894107, PMID:23744328]. Disease-associated missense variants alter channel inactivation and cause loss-of-function, linking CACNB2 to short QT syndrome (S480L) and Brugada syndrome (S142F), with isogenic CRISPR correction rescuing the electrophysiological defects [PMID:35894107, PMID:35955449].","teleology":[{"year":2008,"claim":"Establishing that CACNB2 is a MAGUK-family protein with defined modular architecture framed it as more than a simple channel modulator, raising the possibility of scaffolding functions.","evidence":"cDNA cloning, sequence analysis, and RT-PCR of zebrafish and human loci","pmids":["18419826"],"confidence":"Medium","gaps":["Domain architecture inferred from sequence without functional assignment of SH3/GK domains","Functional consequence of alternative splice variants not tested"]},{"year":2011,"claim":"Conditional adult cardiomyocyte knockout resolved whether CACNB2 is essential throughout life, showing its requirement for L-type current is developmentally staged—critical in embryo, only moderately modulatory in adult.","evidence":"Cre-lox conditional knockout with patch-clamp and protein quantification in adult mouse cardiomyocytes","pmids":["21357697"],"confidence":"High","gaps":["Mechanism of the embryonic-to-adult shift in dependence unresolved","Why no compensatory CaVβ upregulation occurs not explained"]},{"year":2012,"claim":"Zebrafish loss-of-function dissected channel-dependent versus scaffolding roles, showing CACNB2 maintains N-cadherin adherens junctions and supports contractility, proliferation, and chamber morphogenesis.","evidence":"Morpholino knockdown with pharmacological LTCC modulation/rescue and N-cadherin immunostaining in zebrafish","pmids":["22274990"],"confidence":"High","gaps":["Direct physical interaction of CACNB2 with N-cadherin complex not mapped","Extent to which scaffolding is separable from channel function not quantified"]},{"year":2013,"claim":"Allele-specific promoter reporter assays established that regulatory-region variants tune CACNB2 transcription, introducing expression-level control as a disease-relevant variable.","evidence":"Luciferase reporter assay of CACNB2 promoter fragment carrying rs7069292","pmids":["23744328"],"confidence":"Medium","gaps":["In vivo physiological consequence of allele-specific expression not shown","Transcription factors mediating allelic difference unidentified"]},{"year":2014,"claim":"Recombinant electrophysiology of ASD-associated missense variants showed CACNB2 mutations alter channel inactivation kinetics, providing a biophysical basis for variant pathogenicity.","evidence":"Site-directed mutagenesis and whole-cell patch-clamp in HEK-293 cells","pmids":["24752249"],"confidence":"High","gaps":["Phenotypic relevance in neurons or patients not demonstrated","Single heterologous system without native cell context"]},{"year":2017,"claim":"Identification of direct miR-499 binding to the CACNB2 3' UTR revealed a post-transcriptional control layer that also lowers the pore-forming CACNA1C subunit.","evidence":"Luciferase reporter, Argonaute pull-down, and bidirectional miRNA manipulation in HL-1 cardiomyocytes","pmids":["28239561"],"confidence":"High","gaps":["Physiological contexts where miR-499 regulates CACNB2 in vivo not defined","Mechanism by which CACNB2 loss reduces CACNA1C protein not established"]},{"year":2019,"claim":"Overexpression experiments uncovered a channel-independent function, showing CACNB2 drives proliferation through RAS-MAPK without requiring LTCC activity.","evidence":"HEK293 overexpression with nifedipine dissection and Dahl Salt-Sensitive rat kidney expression analysis","pmids":["30992131"],"confidence":"Medium","gaps":["Mechanistic link to RAS-MAPK is correlative without direct pathway reconstitution","Direct molecular partner connecting CACNB2 to RAS-MAPK unidentified"]},{"year":2019,"claim":"Pharmacological work in retinal pigment epithelial cells extended CACNB2-containing channels to VEGF secretion, implicating them in proliferative diabetic retinopathy.","evidence":"Pharmacological LTCC blockade and VEGF measurement in ARPE19 cells","pmids":["31439644"],"confidence":"Low","gaps":["CACNB2-specific role not isolated from general LTCC activity","Single cell line, no loss-of-function for CACNB2 itself"]},{"year":2022,"claim":"Patient-derived hiPSC-CM models with isogenic CRISPR correction established CACNB2 missense variants (S142F, S480L) as causative loss-of-function alleles in Brugada and short QT syndromes, and identified promoter hypermethylation as an additional silencing mechanism.","evidence":"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp, bisulfite sequencing, and demethylase rescue","pmids":["35955449","35894107"],"confidence":"High","gaps":["Trigger for promoter hypermethylation and DNMT upregulation unknown","Generalizability across patient backgrounds not established"]},{"year":2022,"claim":"Neuronal studies generalized miR-499-5p repression of CACNB2 beyond heart, showing it reduces CaV1.2 surface expression and impairs dendritogenesis and memory in a Cacna1c-dependent manner.","evidence":"miRNA overexpression in rat hippocampal neurons in vitro and in vivo with genetic epistasis against Cacna1c haploinsufficiency and behavioral testing","pmids":["35969184"],"confidence":"High","gaps":["Direct biochemical mechanism linking CACNB2 loss to dendritic deficits not resolved","Whether scaffolding versus channel role drives the neuronal phenotype unclear"]},{"year":2026,"claim":"An atrial fibrillation rat model defined a fibrosis-protective role, with CACNB2 overexpression attenuating Ang II profibrotic signaling through modulation of the TGF-β/Smad pathway.","evidence":"In vivo rat AF overexpression model plus primary atrial fibroblast/cardiomyocyte assays with TGF-β/Smad western blotting","pmids":["41748049"],"confidence":"Medium","gaps":["Link to TGF-β/Smad is correlative without direct pathway reconstitution","Whether the antifibrotic effect requires channel activity not tested"]},{"year":null,"claim":"How CACNB2's channel-dependent and channel-independent (RAS-MAPK, TGF-β/Smad, scaffolding) functions are molecularly partitioned and co-regulated remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No direct physical partner identified for the RAS-MAPK or TGF-β/Smad effects","Structural basis distinguishing channel modulation from scaffolding not established","Tissue-specific balance of the multiple functions not mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,3]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,5]}],"pathway":[],"complexes":["L-type voltage-gated calcium channel (CaV1.2)"],"partners":["CACNA1C","CDH2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q08289","full_name":"Voltage-dependent L-type calcium channel subunit beta-2","aliases":["Calcium channel voltage-dependent subunit beta 2","Lambert-Eaton myasthenic syndrome antigen B","MYSB"],"length_aa":660,"mass_kda":73.6,"function":"Beta subunit of voltage-dependent calcium channels which contributes to the function of the calcium channel by increasing peak calcium current (By similarity). Plays a role in shifting voltage dependencies of activation and inactivation of the channel (By similarity). May modulate G protein inhibition (By similarity). May contribute to beta-adrenergic augmentation of Ca(2+) influx in cardiomyocytes, thereby regulating increases in heart rate and contractile force (PubMed:36424916). Involved in membrane targeting of the alpha-1 subunit CACNA1C (PubMed:17525370)","subcellular_location":"Cell membrane, sarcolemma","url":"https://www.uniprot.org/uniprotkb/Q08289/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CACNB2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CACNB2","total_profiled":1310},"omim":[{"mim_id":"611876","title":"BRUGADA SYNDROME 4; BRGDA4","url":"https://www.omim.org/entry/611876"},{"mim_id":"607194","title":"PANCREAS TRANSCRIPTION FACTOR 1, ALPHA SUBUNIT; PTF1A","url":"https://www.omim.org/entry/607194"},{"mim_id":"604433","title":"POTASSIUM CHANNEL, VOLTAGE-GATED, ISK-RELATED SUBFAMILY, MEMBER 3; KCNE3","url":"https://www.omim.org/entry/604433"},{"mim_id":"601462","title":"MYASTHENIC SYNDROME, CONGENITAL, 1A, SLOW-CHANNEL; CMS1A","url":"https://www.omim.org/entry/601462"},{"mim_id":"601144","title":"BRUGADA SYNDROME 1; BRGDA1","url":"https://www.omim.org/entry/601144"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"retina","ntpm":19.5}],"url":"https://www.proteinatlas.org/search/CACNB2"},"hgnc":{"alias_symbol":[],"prev_symbol":["MYSB","CACNLB2"]},"alphafold":{"accession":"Q08289","domains":[{"cath_id":"2.30.30.40","chopping":"91-193","consensus_level":"high","plddt":93.6937,"start":91,"end":193},{"cath_id":"3.40.50.300","chopping":"282-470","consensus_level":"high","plddt":91.4841,"start":282,"end":470}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q08289","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q08289-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q08289-F1-predicted_aligned_error_v6.png","plddt_mean":65.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CACNB2","jax_strain_url":"https://www.jax.org/strain/search?query=CACNB2"},"sequence":{"accession":"Q08289","fasta_url":"https://rest.uniprot.org/uniprotkb/Q08289.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q08289/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q08289"}},"corpus_meta":[{"pmid":"21963141","id":"PMC_21963141","title":"Genetic 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Case reports","url":"https://pubmed.ncbi.nlm.nih.gov/37123658","citation_count":2,"is_preprint":false},{"pmid":"35754833","id":"PMC_35754833","title":"A Post-GWAS Functional Analysis Confirming Effects of Three BTA13 Genes CACNB2, SLC39A12, and ZEB1 on Dairy Cattle Reproduction.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35754833","citation_count":1,"is_preprint":false},{"pmid":"33491517","id":"PMC_33491517","title":"Association study of hypertension susceptibility genes ITGA9, MOV10, and CACNB2 with preeclampsia in Chinese Han population.","date":"2021","source":"The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians","url":"https://pubmed.ncbi.nlm.nih.gov/33491517","citation_count":0,"is_preprint":false},{"pmid":"23744328","id":"PMC_23744328","title":"[Association between CACNB2 gene polymorphisms and essential hypertension].","date":"2013","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23744328","citation_count":0,"is_preprint":false},{"pmid":"40016690","id":"PMC_40016690","title":"The impact of the CACNB2 Rs11013860 polymorphism on grey matter volume and brain function in bipolar disorder.","date":"2025","source":"BMC psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/40016690","citation_count":0,"is_preprint":false},{"pmid":"39965006","id":"PMC_39965006","title":"Genetic evidence for amlodipine's protective role in gastroesophageal reflux disease: A focus on CACNB2.","date":"2025","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/39965006","citation_count":0,"is_preprint":false},{"pmid":"41748049","id":"PMC_41748049","title":"CACNB2 overexpression suppresses atrial fibroblast activation and atrial fibrosis to mitigate atrial fibrillation.","date":"2026","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/41748049","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":16265,"output_tokens":3584,"usd":0.051277,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11190,"output_tokens":3623,"usd":0.073262,"stage2_stop_reason":"end_turn"},"total_usd":0.124539,"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\": 2011,\n      \"finding\": \"Conditional cardiomyocyte-specific excision of the cacnb2 gene in adult mice reduced CaVβ2 protein expression by >96% in isolated cardiac myocytes and reduced L-type calcium current density by <29% at 0 mV, with a slight (non-significant) depolarizing shift in voltage for half-maximal activation, without compensation by other CaVβ proteins or changes in CaV1.2 protein levels. This contrasts with embryonic cardiomyocytes where cacnb2 deletion reduces L-type calcium currents by up to 75% and is lethal.\",\n      \"method\": \"Conditional knockout (Cre-lox), patch-clamp electrophysiology, western blotting, immunofluorescence in adult mouse cardiomyocytes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — conditional KO with multiple orthogonal methods (electrophysiology, protein quantification, functional cardiac assessment) in a single rigorous study\",\n      \"pmids\": [\"21357697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Depletion of β2.1 (CACNB2) in zebrafish using morpholinos caused compromised cardiac function, reduced ventricular cell proliferation, failure of outer curvature cells to elongate during chamber ballooning, and failure of cardiomyocytes to accumulate N-cadherin at the membrane with dissociation under stress. Pharmacological depression of L-type calcium channels (LTCC) mimicked these contractility defects, and LTCC stimulation rescued them, indicating β2.1 phenotypes are at least partly LTCC-dependent. β2.1 also functions as a MAGUK scaffolding protein to maintain N-cadherin-based adherens junctions.\",\n      \"method\": \"Morpholino knockdown in zebrafish, pharmacological LTCC modulation, morphological/histological analysis, immunostaining for N-cadherin\",\n      \"journal\": \"Developmental dynamics : an official publication of the American Association of Anatomists\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function with defined cellular phenotype, pharmacological rescue, multiple orthogonal readouts (contractility, proliferation, cell morphology, N-cadherin localization)\",\n      \"pmids\": [\"22274990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Zebrafish CACNB2 (β2.1 and β2.2) are membrane-associated guanylate kinase (MAGUK)-family proteins with conserved SH3 and guanylate kinase domains. The genes undergo alternative splicing at the N-terminus and within the internal HOOK domain, and splicing is temporally and spatially regulated with distinct transcript variant subsets in embryonic versus adult heart.\",\n      \"method\": \"cDNA cloning, sequence analysis, RT-PCR, comparative genomics of teleost and human loci\",\n      \"journal\": \"BMC molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — structural/domain characterization by cloning and sequencing with expression validation, single lab but multiple methods\",\n      \"pmids\": [\"18419826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Three rare missense mutations in CACNB2 (G167S, S197F, F240L) found in ASD-affected families alter whole-cell Ba2+ currents through calcium channels in HEK-293 cells. G167S and S197F displayed significantly decelerated time-dependent inactivation and increased sensitivity of voltage-dependent inactivation, while F240L showed significantly accelerated time-dependent inactivation.\",\n      \"method\": \"Recombinant expression in HEK-293 cells, whole-cell patch-clamp electrophysiology, site-directed mutagenesis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro electrophysiological reconstitution with specific mutations, multiple biophysical parameters measured, single lab\",\n      \"pmids\": [\"24752249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"miR-499 directly targets the 3' UTR of CACNB2, as confirmed by luciferase reporter assay and Argonaute pull-down of CACNB2 mRNA in miR-499 mimic-transfected HL-1 cells. miR-499 mimic transfection downregulated CACNB2 protein expression, while miR-499 inhibitor upregulated it. Downregulation of CACNB2 also led to downregulation of the pore-forming α-subunit (CACNA1C) protein levels.\",\n      \"method\": \"Luciferase reporter assay, Argonaute pull-down, miRNA mimic/inhibitor transfection, western blotting in HL-1 cardiomyocytes\",\n      \"journal\": \"BBA clinical\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding confirmed by two orthogonal methods (luciferase assay and Argonaute pull-down), bidirectional miRNA manipulation, functional protein consequence measured\",\n      \"pmids\": [\"28239561\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"miR-499-5p directly targets CACNB2 in rat hippocampal neurons, reducing surface expression and activity of the L-type calcium channel Cav1.2, impairing dendritogenesis. miR-499-5p overexpression in the hippocampus in vivo induced short-term memory impairments selectively in rats haploinsufficient for Cacna1c (the Cav1.2 pore-forming subunit), establishing a CACNB2-Cav1.2 functional epistatic interaction.\",\n      \"method\": \"miRNA overexpression in rat hippocampal neurons (in vitro and in vivo), surface expression assays, calcium channel activity recordings, behavioral testing, genetic epistasis with Cacna1c haploinsufficient rats\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (molecular, electrophysiological, behavioral) with in vivo genetic epistasis confirming functional interaction\",\n      \"pmids\": [\"35969184\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In hiPSC-CMs from an SQT5 patient carrying the CACNB2 S480L variant, decreased L-type Ca2+ current and shortened action potential duration were associated with increased DNA methylation of CpG islands in the CACNB2 promoter and upregulated DNA methyltransferases. Overexpression of a demethylation enzyme rescued decreased CACNB2 expression and L-type Ca2+ current, establishing promoter hypermethylation as an epigenetic mechanism of CACNB2 loss-of-function.\",\n      \"method\": \"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp electrophysiology, western blotting, dot blotting, bisulfite sequencing, demethylase overexpression rescue\",\n      \"journal\": \"Europace\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — isogenic CRISPR correction, functional rescue by demethylase overexpression, multiple orthogonal epigenetic and electrophysiological methods\",\n      \"pmids\": [\"35894107\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The CACNB2 variant S142F causes loss-of-function of L-type calcium channels in hiPSC-CMs from a Brugada syndrome patient: reduced ICa-L, shifted inactivation curve to more positive potential, accelerated recovery from inactivation, and decreased CACNB2 protein expression. CRISPR/Cas9 correction of the variant rescued all these changes to normal.\",\n      \"method\": \"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp electrophysiology, western blotting, arrhythmia event monitoring\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — isogenic CRISPR correction with complete phenotype rescue, multiple electrophysiological and protein-level readouts\",\n      \"pmids\": [\"35955449\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CACNB2 overexpression in HEK293 cells triggers cell proliferation via upregulation of the RAS-MAPK pathway. This effect was independent of LTCC activity, as nifedipine (LTCC blocker) failed to inhibit RAS-MAPK pathway gene expression or affect apoptosis markers in CACNB2-overexpressing cells. In hypertensive Dahl Salt-Sensitive rat kidneys on high-salt diet, CACNB2 expression and RAS-MAPK mRNA levels were both elevated.\",\n      \"method\": \"HEK293 overexpression, cell proliferation assay, gene expression analysis, pharmacological LTCC blockade (nifedipine), in vivo rat model gene expression\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — overexpression with pharmacological dissection from LTCC activity, but mechanistic link to RAS-MAPK is correlative in vivo and lacks direct pathway reconstitution\",\n      \"pmids\": [\"30992131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"L-type calcium channels (containing CACNB2 as β2 subunit) regulate VEGF expression and secretion from retinal pigment epithelial cells (ARPE19), supporting a role for CACNB2 in regulation of VEGF in proliferative diabetic retinopathy pathogenesis.\",\n      \"method\": \"Pharmacological L-type calcium channel blockade in ARPE19 cells, VEGF expression and secretion measurement\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single cell-line pharmacological experiment, CACNB2-specific role not directly isolated from general LTCC activity\",\n      \"pmids\": [\"31439644\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The rs7069292 SNP in the 5' regulatory region of CACNB2 affects promoter activity: the C allele showed significantly increased promoter activity compared to the T allele in luciferase reporter assays, indicating that a T>C mutation in the regulatory region can modulate CACNB2 expression.\",\n      \"method\": \"Luciferase reporter gene assay with CACNB2 promoter fragment containing rs7069292\",\n      \"journal\": \"Zhonghua yi xue yi chuan xue za zhi\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct functional reporter assay establishing allele-specific promoter activity, single lab single method\",\n      \"pmids\": [\"23744328\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CACNB2 overexpression in a rat AF model improved electrophysiological parameters, reduced atrial fibrosis and inflammation, and attenuated profibrotic effects of Ang II on primary atrial fibroblasts. In primary atrial cardiomyocytes, CACNB2 overexpression modulated calcium handling and oxidative stress. The protective effect was accompanied by modulation of the TGF-β/Smad pathway, indicating CACNB2 directly regulates this fibrotic signaling axis.\",\n      \"method\": \"In vivo rat AF model with CACNB2 overexpression, electrophysiological measurements, histology, fibrotic marker expression (α-SMA, collagen I/III), primary atrial fibroblast culture with Ang II stimulation, western blotting for TGF-β/Smad pathway\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo and in vitro overexpression with multiple orthogonal readouts, but single lab and mechanistic link to TGF-β/Smad is correlative without direct pathway reconstitution\",\n      \"pmids\": [\"41748049\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CACNB2 encodes the CaVβ2 auxiliary subunit of L-type voltage-gated calcium channels (CaV1.2): it traffics the pore-forming α1C subunit to the plasma membrane, modulates channel kinetics (inactivation rate and voltage-dependence), and is essential for normal L-type calcium current in embryonic cardiomyocytes (where loss is lethal) but only a moderate modulator in adult cardiomyocytes; it also functions as a MAGUK scaffolding protein to maintain N-cadherin-based adherens junctions in the heart; its expression is post-transcriptionally repressed by miR-499-5p (via direct 3' UTR binding) and epigenetically silenced by promoter hypermethylation in certain disease states; disease-associated missense mutations alter channel inactivation kinetics; and CACNB2 additionally regulates cell proliferation via the RAS-MAPK pathway independently of LTCC activity, modulates TGF-β/Smad-dependent atrial fibrosis, and regulates VEGF secretion from retinal pigment epithelial cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CACNB2 encodes the CaVβ2 auxiliary subunit of L-type voltage-gated calcium channels, where it controls L-type calcium current and channel inactivation kinetics in cardiomyocytes [#0, #3]. Its functional importance is developmentally staged: embryonic cardiomyocyte deletion is lethal with up to 75% loss of L-type current, whereas conditional excision in adult myocytes reduces current density by less than 29% without compensatory CaVβ upregulation or loss of CaV1.2 protein, indicating a moderate modulatory role in mature heart [#0]. As a MAGUK-family scaffold with conserved SH3 and guanylate kinase domains, CACNB2 also maintains N-cadherin-based adherens junctions and supports cardiac contractility, proliferation, and chamber morphogenesis, phenotypes that are at least partly dependent on L-type channel activity [#1, #2]. Beyond its channel-associated functions, CACNB2 drives cell proliferation through the RAS-MAPK pathway independently of channel activity [#8] and attenuates atrial fibrosis via modulation of TGF-β/Smad signaling [#11]. CACNB2 expression is post-transcriptionally repressed by miR-499/miR-499-5p binding to its 3' UTR—reducing CaV1.2 surface expression in both cardiomyocytes and neurons—and is silenced by promoter hypermethylation, with allele-specific promoter variants further tuning its expression [#4, #5, #6, #10]. Disease-associated missense variants alter channel inactivation and cause loss-of-function, linking CACNB2 to short QT syndrome (S480L) and Brugada syndrome (S142F), with isogenic CRISPR correction rescuing the electrophysiological defects [#6, #7].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Establishing that CACNB2 is a MAGUK-family protein with defined modular architecture framed it as more than a simple channel modulator, raising the possibility of scaffolding functions.\",\n      \"evidence\": \"cDNA cloning, sequence analysis, and RT-PCR of zebrafish and human loci\",\n      \"pmids\": [\"18419826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Domain architecture inferred from sequence without functional assignment of SH3/GK domains\", \"Functional consequence of alternative splice variants not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Conditional adult cardiomyocyte knockout resolved whether CACNB2 is essential throughout life, showing its requirement for L-type current is developmentally staged—critical in embryo, only moderately modulatory in adult.\",\n      \"evidence\": \"Cre-lox conditional knockout with patch-clamp and protein quantification in adult mouse cardiomyocytes\",\n      \"pmids\": [\"21357697\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of the embryonic-to-adult shift in dependence unresolved\", \"Why no compensatory CaVβ upregulation occurs not explained\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Zebrafish loss-of-function dissected channel-dependent versus scaffolding roles, showing CACNB2 maintains N-cadherin adherens junctions and supports contractility, proliferation, and chamber morphogenesis.\",\n      \"evidence\": \"Morpholino knockdown with pharmacological LTCC modulation/rescue and N-cadherin immunostaining in zebrafish\",\n      \"pmids\": [\"22274990\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct physical interaction of CACNB2 with N-cadherin complex not mapped\", \"Extent to which scaffolding is separable from channel function not quantified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Allele-specific promoter reporter assays established that regulatory-region variants tune CACNB2 transcription, introducing expression-level control as a disease-relevant variable.\",\n      \"evidence\": \"Luciferase reporter assay of CACNB2 promoter fragment carrying rs7069292\",\n      \"pmids\": [\"23744328\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo physiological consequence of allele-specific expression not shown\", \"Transcription factors mediating allelic difference unidentified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Recombinant electrophysiology of ASD-associated missense variants showed CACNB2 mutations alter channel inactivation kinetics, providing a biophysical basis for variant pathogenicity.\",\n      \"evidence\": \"Site-directed mutagenesis and whole-cell patch-clamp in HEK-293 cells\",\n      \"pmids\": [\"24752249\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phenotypic relevance in neurons or patients not demonstrated\", \"Single heterologous system without native cell context\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identification of direct miR-499 binding to the CACNB2 3' UTR revealed a post-transcriptional control layer that also lowers the pore-forming CACNA1C subunit.\",\n      \"evidence\": \"Luciferase reporter, Argonaute pull-down, and bidirectional miRNA manipulation in HL-1 cardiomyocytes\",\n      \"pmids\": [\"28239561\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological contexts where miR-499 regulates CACNB2 in vivo not defined\", \"Mechanism by which CACNB2 loss reduces CACNA1C protein not established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Overexpression experiments uncovered a channel-independent function, showing CACNB2 drives proliferation through RAS-MAPK without requiring LTCC activity.\",\n      \"evidence\": \"HEK293 overexpression with nifedipine dissection and Dahl Salt-Sensitive rat kidney expression analysis\",\n      \"pmids\": [\"30992131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link to RAS-MAPK is correlative without direct pathway reconstitution\", \"Direct molecular partner connecting CACNB2 to RAS-MAPK unidentified\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Pharmacological work in retinal pigment epithelial cells extended CACNB2-containing channels to VEGF secretion, implicating them in proliferative diabetic retinopathy.\",\n      \"evidence\": \"Pharmacological LTCC blockade and VEGF measurement in ARPE19 cells\",\n      \"pmids\": [\"31439644\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"CACNB2-specific role not isolated from general LTCC activity\", \"Single cell line, no loss-of-function for CACNB2 itself\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Patient-derived hiPSC-CM models with isogenic CRISPR correction established CACNB2 missense variants (S142F, S480L) as causative loss-of-function alleles in Brugada and short QT syndromes, and identified promoter hypermethylation as an additional silencing mechanism.\",\n      \"evidence\": \"hiPSC-CM generation, CRISPR/Cas9 isogenic correction, patch-clamp, bisulfite sequencing, and demethylase rescue\",\n      \"pmids\": [\"35955449\", \"35894107\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trigger for promoter hypermethylation and DNMT upregulation unknown\", \"Generalizability across patient backgrounds not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Neuronal studies generalized miR-499-5p repression of CACNB2 beyond heart, showing it reduces CaV1.2 surface expression and impairs dendritogenesis and memory in a Cacna1c-dependent manner.\",\n      \"evidence\": \"miRNA overexpression in rat hippocampal neurons in vitro and in vivo with genetic epistasis against Cacna1c haploinsufficiency and behavioral testing\",\n      \"pmids\": [\"35969184\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical mechanism linking CACNB2 loss to dendritic deficits not resolved\", \"Whether scaffolding versus channel role drives the neuronal phenotype unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"An atrial fibrillation rat model defined a fibrosis-protective role, with CACNB2 overexpression attenuating Ang II profibrotic signaling through modulation of the TGF-β/Smad pathway.\",\n      \"evidence\": \"In vivo rat AF overexpression model plus primary atrial fibroblast/cardiomyocyte assays with TGF-β/Smad western blotting\",\n      \"pmids\": [\"41748049\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Link to TGF-β/Smad is correlative without direct pathway reconstitution\", \"Whether the antifibrotic effect requires channel activity not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CACNB2's channel-dependent and channel-independent (RAS-MAPK, TGF-β/Smad, scaffolding) functions are molecularly partitioned and co-regulated remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct physical partner identified for the RAS-MAPK or TGF-β/Smad effects\", \"Structural basis distinguishing channel modulation from scaffolding not established\", \"Tissue-specific balance of the multiple functions not mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": []}\n    ],\n    \"complexes\": [\"L-type voltage-gated calcium channel (CaV1.2)\"],\n    \"partners\": [\"CACNA1C\", \"CDH2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}