CACNA1D Research Articles

8294 Association between gene mutations and DNA methylation of CYP11B2 in aldosterone-producing adenoma

Abstract Disclosure: M. Kometani: None. R. Mizoguchi: None. M. Demura: None. K. Aiga: None. S. Konishi: None. D. Aono: None. S. Karashima: None. Y. Takeda: None. T. Yoneda: None. Context: Primary aldosteronism (PA) causes hypertension and cardiovascular complications. Recently, in aldosterone producing adenomas (APA), various genetic mutations have been identified. In addition, epigenetic mechanisms, such as DNA methylation, are also involved in excessive aldosterone production. Several studies have shown that aldosterone synthase (CYP11B2) is hypomethylated in APA. On the other hand, the relationship between specific genetic variants identified in APA and DNA methylation has not been fully clarified. Objective: To investigate the relationship between specific genetic mutations in APA and DNA methylation of CYP11B2. Methods: We analyzed 48 patients (female 23 cases) diagnosed with APA and treated between 2001 and 2022. First, Gene mutation analysis using next-generation sequencing was performed. KCNJ5, ATP1A1, ATP2B3, CACNA1D, and CACNA1H, which are known mutations in PA, and PRKACA, PRKA1A, GNAS, CTNNB1, and ARMC5, which are known mutations in Cushing’s syndrome, were evaluated. Next, DNA methylation analysis of the CYP11B2 promoter using pyrosequencing were performed using APA. We targeted three CpG regions near the transcription start site of CYP11B2. Results: The respective mean values for all patients were: age 52 years, systolic blood pressure 138 mmHg, diastolic blood pressure 87 mmHg, ARR 1,326, serum potassium level 3.4 mEq/L, and tumor diameter 15 mm. Genetic mutation analysis revealed KCNJ5 gene mutations in 33 of the 48 patients. Among the other cases, mutations in the CTNNB1 gene were found in three cases, mutations in the ATP1A1 gene in two cases, mutations in the CACNA1D gene in one case, and PRKACA gene mutations in one case. The remaining seven patients had no mutations in any of the analyzed genes. When DNA methylation of the promoter region of CYP11B2 was analyzed in APAs with and without mutations in KCNJ5, we found that in all three CpG regions, DNA methylation rate was significantly reduced in APAs with mutations in KCNJ5 gene (CpG1 22% vs. 30%, CpG2 42% vs. 73%, CpG3 47% vs. 75%, respectively). Conclusions: The most common genetic mutation in APA was the KCNJ5 mutation; APA with the KCNJ5 mutation had significantly lower methylation rates than CYP11B2. This suggests that genetic mutations in APA affect DNA methylation and result in hormone overproduction. Presentation: 6/3/2024

8401 Genetic Characterization of a Case of Primary Aldosteronism in an 11-Year-Old Girl carrying a Germline VUS of CACNA1H and a Somatic Mutation of CTNNB1

Abstract Disclosure: S. Parisien-La Salle: None. G. Van Vliet: None. G. Corbeil: None. M. Labrecque: None. M. Tétreault: None. I. Bourdeau: None. Introduction: Primary aldosteronism is a frequent cause of secondary hypertension in adults but is rare in children. We report the case and genetic studies of an 11 yo girl presenting with primary aldosteronism at puberty. Case presentation: An 11-year-old female patient was referred to the pediatric endocrinology clinic for hypertension (166/118). Her past medical history and family history were unremarkable. She reported polyuria, polydipsia and occasional headaches and abdominal pain. Her Tanner stage indicated that puberty was initiated (P2M2). An abdominal CT revealed a 9x10x11cm right adrenal mass with calcifications and a necrotic zone. On [1]8F-FDG PET/CT, the mass had an uptake of 2.9 SUVmax. Laboratory results revealed hypokalemia (K: 2.6 mmol/L [N: 3.5-4.5]) and elevated aldosterone (1712.8 pmol/L [N: 110-1330]) with suppressed renin (0.2 ng/ml/h [N: <5.3]). Her urinary aldosterone level was elevated (114 nmol/day [N: <67]). The rest of the biochemical adrenal panel was normal. Patient underwent a right adrenalectomy by laparotomy. The pathology report showed an adrenal tumor without capsular or vascular invasion. The only malignancy criterion was an area of necrosis and the ki-67% proliferation index was < 1%. Genetic investigations: After informed consent, the patient underwent germline analysis for the chimeric gene CYP11B2/CYP11B1 (Ruhr University Bochum, Germany) and a multigene panel including KCNJ5, CACNA1D, CACNA1H and CLCN2 genes (Fulgent, CA), which were both negative except for a variant of unknown significance (VUS) that was identified in CACNA1H (c.3868G>A, p.Val1290Ile) with a minor allele frequency of 3.291E-5 (GnomAD). Tumor DNA was extracted after adrenalectomy from fresh frozen tissues. Somatic genetic analysis of GNAS, CTNNB1, KCNJ5, ATP1A1, ATP2B3 and CACNA1D was performed using direct Sanger Sequencing (Genome Quebec Innovation Centre) and revealed a heterozygous missence pathogenic variant in the CTNNB1 gene (c.121 A>G p.Thr41Ala). This mutation was absent in leukocyte DNA of the patient. Immunohistochemistry of the adrenal tumor disclosed strong cytoplasmic β-catenin staining in most tumor cells (monoclonal anti-β-catenin antibody; BD Transduction Laboratories). RNA-sequencing of patient tumor RNA was performed (Research Center CHU Québec) and compared to human adrenal total RNA (Clontech, Mountain View, CA). Pathway enrichment analysis showed activation of the Wnt signaling pathway. No variant was identified in GNAQ or GNA11 genes. However, GNRHR was upregulated compared to the control sample with a log2 fold change of 3.96 (p=0.000074). Conclusion: We present a rare pediatric case of an aldosterone producing adenoma harbouring a somatic β-catenin pathogenic variant with upregulation of GNRHR. The implication of the germline CACNA1H VUS still needs to be clarified. Presentation: 6/3/2024

Novel heterozygous mutation of CACNA2D1 gene in a Chinese family with arrhythmia

BackgroundPrimary electrical disorders (PEDs) are a group of cardiac rhythm abnormalities that occur in the absence of detectable structural heart disease and are a significant cause of sudden cardiac death (SCD). The initiation of cardiac muscle contraction and relaxation is orchestrated by the action potential (AP), generated through ionic changes across the membrane. Mutations in the AP-related gene CACNA2D1 have been identified as a causative factor for PED.MethodsWe recruited a Chinese family with a history of arrhythmia. The proband has experienced palpitations and chest tightness for over 40 years, with symptoms worsening over the past year. Whole exome sequencing (WES) was used to determine the genetic etiologies in this family.ResultsA novel heterozygous missense mutation (NM_000722.3: c.1685G > C;p.G562A) of CACNA2D1 gene was detected. Genotyping of the proband’s parents indicated that the arrhythmia phenotype in the proband was caused by a de novo mutation.ConclusionsWES was utilized to explore the genetic etiology in a family with arrhythmia, leading to the identification of a novel mutation in the CACNA2D1 gene. This study not only expands the mutation spectrum of the CACNA2D1 gene but also contributes to genetic counseling and clinical diagnosis for this family.

A Novel De Novo Gain-of-Function CACNA1D Variant in Neurodevelopmental Disease With Congenital Tremor, Seizures, and Hypotonia.

De novo gain-of-function variants in the CACNA1D gene, encoding the L-type voltage-gated Ca2+ channel CaV1.3, cause a multifaceted syndrome. Patients show variable degrees of autism spectrum disorder, developmental delay, epilepsy, and other neurologic and endocrine abnormalities (primary aldosteronism and/or hyperinsulinemic hypoglycemia). We study here a novel variant [c.3506G>A, NM_000720.4, p.(G1169D)] in 2 children with the same CACNA1D mutation but different disease severity. The clinical data of the study patients were collected. After molecular analysis and cloning by site-directed mutagenesis, patch-clamp recordings of transfected tsA201 cells were conducted in whole-cell configuration. The functional effects of wild-type and mutated channels were analyzed. One child is a severely affected boy with a novel de novo CACNA1D variant with additional clinical symptoms including prenatal-onset tremor, congenital respiratory insufficiency requiring continuous positive airway pressure ventilation, and sensorineural deafness. Despite episodes of hypoglycemia, insulin levels were normal. Aldosterone:renin ratios as a screening parameter for primary aldosteronism were variable. In the second patient, putative mosaicism of the p.(G1169D) variant was associated with a less severe phenotype. Patch-clamp electrophysiology of the p.(G1169D) variant in a heterologous expression system revealed pronounced activity-enhancing gating changes, including a shift of channel activation and inactivation to more hyperpolarized potentials, as well as impaired channel inactivation and deactivation. Despite retained sensitivity to the Ca2+ channel blocker isradipine in vitro, no beneficial effects of isradipine or nifedipine treatment were observed in the index case. Through this report, we expand the knowledge about the disease presentation in patients with CACNA1D variants and show the novel variant's modulatory effects on CaV1.3 gating.

Nerve injury augments Cacna2d1 transcription via CK2-mediated phosphorylation of the histone deacetylase HDAC2 in dorsal root ganglia

Development of chronic neuropathic pain involves complex synaptic and epigenetic mechanisms. Nerve injury causes sustained upregulation of α2δ-1 (encoded by the Cacna2d1 gene) in the dorsal root ganglion (DRG), contributing to pain hypersensitivity by directly interacting with and augmenting presynaptic NMDA receptor activity in the spinal dorsal horn. Under normal conditions, histone deacetylase 2 (HDAC2) is highly enriched at the Cacna2d1 gene promoter in the DRG, which constitutively suppresses Cacna2d1 transcription. However, nerve injury leads to HDAC2 dissociation from the Cacna2d1 promoter, promoting the enrichment of active histone marks and Cacna2d1 transcription in primary sensory neurons. In this study, we determined the mechanism by which nerve injury diminishes HDAC2 occupancy at the Cacna2d1 promoter in the DRG. Spinal nerve injury in rats increased serine-394 phosphorylation of HDAC2 in the DRG. Coimmunoprecipitation showed that nerve injury enhanced the physical interaction between HDAC2 and casein kinase II (CK2) in the DRG. Furthermore, repeated intrathecal treatment with CX-4945, a potent and specific CK2 inhibitor, markedly reversed nerve injury–induced pain hypersensitivity, HDAC2 phosphorylation, and α2δ-1 expression levels in the DRG. In addition, treatment with CX-4945 largely restored HDAC2 enrichment at the Cacna2d1 promoter and reduced the elevated levels of acetylated H3 and H4 histones, particularly H3K9ac and H4K5ac, at the Cacna2d1 promoter in the injured DRG. These findings suggest that nerve injury increases CK2 activity and CK2-HDAC2 interactions, which enhance HDAC2 phosphorylation in the DRG. This, in turn, diminishes HDAC2 enrichment at the Cacna2d1 promoter, thereby promoting Cacna2d1 transcription.

Association Study of CACNA1D, KCNJ11, KCNQ1, and CACNA1E Single-Nucleotide Polymorphisms with Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus (T2DM) is a complex chronic disease characterized by decreased insulin secretion and the development of insulin resistance. Previous genome-wide association studies demonstrated that single-nucleotide polymorphisms (SNPs) present in genes coding for ion channels involved in insulin secretion increase the risk of developing this disease. We determined the association of 16 SNPs found in CACNA1D, KCNQ1, KCNJ11, and CACNA1E genes and the increased probability of developing T2DM. In this work, we performed a case-control study in 301 Mexican adults, including 201 cases with diabetes and 100 controls without diabetes. Our findings indicate a moderate association between T2DM and the C allele, and the C/C genotype of rs312480 within CACNA1D. The CAG haplotype surprisingly showed a protective effect, whereas the CAC and CGG haplotypes have a strong association with T2DM. The C allele and C/C genotype of rs5219 were significantly associated with diabetes. Also, an association was observed between diabetes and the A allele and the A/A genotype of rs3753737 and rs175338 in CACNA1E. The TGG and CGA haplotypes were also found to be significantly associated. The findings of this study indicate that the SNPs examined could serve as a potential diagnostic tool and contribute to the susceptibility of the Mexican population to this disease.

Anamnestic, clinical, laboratory and molecular genetic characteristics of patients with neonatal diabetes mellitus

BACKGROUND: Currently, there is an increase in the incidence of diabetes mellitus throughout the world, including the steadily increasing number of rare, genetically determined forms of diabetes. Of particular interest are monogenic forms, including neonatal diabetes mellitus, which is a rare heterogeneous disease that manifests, as a rule, in the first 6 months of a child’s life, characterized by a severe labile course and a high risk of complications. Neonatal diabetes mellitus is a rare heterogeneous disease that usually manifests itself in the first 6 months of a child’s life, characterized by a severe, labile course and a high risk of complications. Currently, more than 25 genes are known, mutations in which cause both permanent and transient neonatal diabetes mellitus, as well as syndromic variants of this disease, which are of particular interest due to their severity and polymorphic clinical picture. In this regard, timely verification of the diagnosis is of particular importance. AIM: The aim of this study is to increase the efficiency of diagnosis of neonatal diabetes mellitus based on the analysis of anamnestic, clinical, laboratory and molecular genetic characteristics of patients. MATERIALS AND METHODS: 14 patients with transient and permanent neonatal diabetes mellitus were examined. RESULTS: 11 (78.6%) patients had isolated neonatal diabetes, in three of them the disease was verified in the structure of hereditary syndromes (Wolcott–Rallison syndrome, IPEX syndrome and Donohue syndrome). According to molecular genetic analysis, 14 variants were found in the genes ABCC8, KCNJ11, GCK, GATA6, WFS1, CACNA1D, EIF2AK3, FOXP3, PAX4, INSR, IGF1R, three of which were not previously described in the literature. CONCLUSIONS: The clinical heterogeneity identified in patients is determined primarily by the diversity of verified variants in causative genes. New variants in the CACNA1D and IGF1R genes that may be associated with the development of NDM, remain poorly understood and require further research.

Deletion of the α2δ-1 calcium channel subunit increases excitability of mouse chromaffin cells.

High voltage-gated Ca2+ channels (HVCCs) shape the electrical activity and control hormone release in most endocrine cells. HVCCs are multi-subunit protein complexes formed by the pore-forming α1 and the auxiliary β, α2δ and γ subunits. Four genes code for the α2δ isoforms. At the mRNA level, mouse chromaffin cells (MCCs) express predominantly the CACNA2D1 gene coding for the α2δ-1 isoform. Here we show that α2δ-1 deletion led to ∼60% reduced HVCC Ca2+ influx with slower inactivation kinetics. Pharmacological dissection showed that HVCC composition remained similar in α2δ-1-/- MCCs compared to wild-type (WT), demonstrating that α2δ-1 exerts similar functional effects on all HVCC isoforms. Consistent with reduced HVCC Ca2+ influx, α2δ-1-/- MCCs showed reduced spontaneous electrical activity with action potentials (APs) having a shorter half-maximal duration caused by faster rising and decay slopes. However, the induced electrical activity showed opposite effects with α2δ-1-/- MCCs displaying significantly higher AP frequency in the tonic firing mode as well as an increase in the number of cells firing AP bursts compared to WT. This gain-of-function phenotype was caused by reduced functional activation of Ca2+-dependent K+ currents. Additionally, despite the reduced HVCC Ca2+ influx, the intracellular Ca2+ transients and vesicle exocytosis or endocytosis were unaltered in α2δ-1-/- MCCs compared to WT during sustained stimulation. In conclusion, our study shows that α2δ-1 genetic deletion reduces Ca2+ influx in cultured MCCs but leads to a paradoxical increase in catecholamine secretion due to increased excitability. KEY POINTS: Deletion of the α2δ-1 high voltage-gated Ca2+ channel (HVCC) subunit reduces mouse chromaffin cell (MCC) Ca2+ influx by ∼60% but causes a paradoxical increase in induced excitability. MCC intracellular Ca2+ transients are unaffected by the reduced HVCC Ca2+ influx. Deletion of α2δ-1 reduces the immediately releasable pool vesicle exocytosis but has no effect on catecholamine (CA) release in response to sustained stimuli. The increased electrical activity and CA release from MCCs might contribute to the previously reported cardiovascular phenotype of patients carrying α2δ-1 loss-of-function mutations.

Genome-wide association analysis explores the genetic loci of amino acid content in duck’s breast muscle

BackgroundAmino acids are the basic components of protein and an important index to evaluate meat quality. With the rapid development of genomics, candidate regions and genes affecting amino acid content in livestock and poultry have been gradually revealed. Hence, genome-wide association study (GWAS) can be used to screen candidate loci associated with amino acid content in duck meat.ResultIn the current study, the content of 16 amino acids was detected in 358 duck breast muscles. The proportion of Glu to the total amino acid content was relatively high, and the proportion was 0.14. However, the proportion of Met content was relatively low, at just 0.03. By comparative analysis, significant differences were found between males and females in 3 amino acids, including Ser, Met, and Phe. In addition, 12 SNPs were significantly correlated with Pro content by GWAS analysis, and these SNPs were annotated by 7 protein-coding genes; 8 significant SNPs were associated with Tyr content, and these SNPs were annotated by 6 protein-coding genes. At the same time, linkage disequilibrium (LD) analysis was performed on these regions with significant signals. The results showed that three SNPs in the 55–56 Mbp region of chromosome 3 were highly correlated with the leader SNP (chr3:55526954) that affected Pro content (r2 > 0.6). Similarly, LD analysis showed that there were three SNPs in the 21.2–21.6 Mbp region of chromosome 13, which were highly correlated with leader SNP (chr13:21421661) (r2 > 0.6). Moreover, Through functional enrichment analysis of all candidate genes. The results of GO enrichment analysis showed that several significant GO items were associated with amino acid transport function, including amino acid transmembrane transport and glutamine transport. The results further indicate that these candidate genes are closely associated with amino acid transport. Among them, key candidate genes include SLC38A1. For KEGG enrichment analysis, CACNA2D3 and CACNA1D genes were covered by significant pathways.ConclusionIn this study, GWAS analysis found a total of 28 significant SNPs affecting amino acid content. Through gene annotation, a total of 20 candidate genes were screened. In addition, Through LD analysis and enrichment analysis, we considered that SERAC1, CACNA2D3 and SLC38A1 genes are important candidate genes affecting amino acid content in duck breast muscle.

Isradipine therapy in Cacna1dIle772Met/+ mice ameliorates primary aldosteronism and neurologic abnormalities.

Somatic gain-of-function mutations in the L-type calcium channel CaV1.3 (CACNA1D gene) cause adrenal aldosterone-producing adenomas and micronodules. De novo germline mutations are found in a syndrome of primary aldosteronism, seizures, and neurologic abnormalities (PASNA) as well as in autism spectrum disorder. Using CRISPR/Cas9, we here generated mice with a Cacna1d gain-of-function mutation found in both adenomas and PASNA syndrome (Cacna1dIle772Met/+). These mice show reduced body weight and increased mortality from weaning to approximately 100 days of age. Male mice do not breed, likely due to neuromotor impairment, and the offspring of female mice die perinatally, likely due to lack of maternal care. Mice generated by in vitro fertilization showed elevated intracellular calcium in the aldosterone-producing zona glomerulosa, an elevated aldosterone/renin ratio, and persistently elevated serum aldosterone on a high-salt diet as signs of primary aldosteronism. Anesthesia with ketamine and xylazine induced tonic-clonic seizures. Neurologic abnormalities included hyperlocomotion, impaired performance in the rotarod test, impaired nest building, and slight changes in social behavior. Intracellular calcium in the zona glomerulosa, aldosterone levels, and rotarod performance responded to treatment with the calcium channel blocker isradipine, with implications for the therapy of patients with aldosterone-producing lesions and with PASNA syndrome.

The human channel gating-modifying A749G CACNA1D (Cav1.3) variant induces a neurodevelopmental syndrome-like phenotype in mice.

Germline de novo missense variants of the CACNA1D gene, encoding the pore-forming α1 subunit of Cav1.3 L-type Ca2+ channels (LTCCs), have been found in patients with neurodevelopmental and endocrine dysfunction, but their disease-causing potential is unproven. These variants alter channel gating, enabling enhanced Cav1.3 activity, suggesting Cav1.3 inhibition as a potential therapeutic option. Here we provide proof of the disease-causing nature of such gating-modifying CACNA1D variants using mice (Cav1.3AG) containing the A749G variant reported de novo in a patient with autism spectrum disorder (ASD) and intellectual impairment. In heterozygous mutants, native LTCC currents in adrenal chromaffin cells exhibited gating changes as predicted from heterologous expression. The A749G mutation induced aberrant excitability of dorsomedial striatum-projecting substantia nigra dopamine neurons and medium spiny neurons in the dorsal striatum. The phenotype observed in heterozygous mutants reproduced many of the abnormalities described within the human disease spectrum, including developmental delay, social deficit, and pronounced hyperactivity without major changes in gross neuroanatomy. Despite an approximately 7-fold higher sensitivity of A749G-containing channels to the LTCC inhibitor isradipine, oral pretreatment over 2 days did not rescue the hyperlocomotion. Cav1.3AG mice confirm the pathogenicity of the A749G variant and point toward a pathogenetic role of altered signaling in the dopamine midbrain system.

CACNA1D Gene Polymorphisms Associate With Increased Blood Pressure and Salt Sensitivity of Blood Pressure in White Individuals.

Disease-causing mutations in CACNA1D gene occur in aldosterone-producing adenomas and familial hyperaldosteronism. We determined whether single nucleotide polymorphisms in CACNA1D gene associate with higher aldosterone resulting in salt sensitivity of blood pressure (BP) and increased BP in men and women. Data were obtained from the HyperPATH (International Hypertension Pathotypes) cohort, where participants completed a cross-over intervention of liberal and restricted sodium diets. Multi-Ethnic Genotyping Array identified 104 CACNA1D single nucleotide polymorphisms that met quality control. Single nucleotide polymorphism is rs7612148 strongly associated with systolic BP and was selected for study in 521 White participants in 3 scenarios ([1] hypertensives; [2] normotensives; [3] total population=hypertensives+normotensives) using multivariate regression analysis. In the total population and hypertensives, but not normotensives, risk allele carriers (CC, GC), as compared with nonrisk allele homozygotes (GG), exhibited higher salt sensitivity of BP and, on liberal sodium diet, higher systolic BP, lower baseline and angiotensin II-stimulated aldosterone, and lower plasma renin activity. On restricted sodium diet, BP was similar across genotypes, suggesting sodium restriction corrected/neutralized the genotype effect on BP. Because increased aldosterone did not seem to drive the increased salt sensitivity of BP and increased BP on liberal sodium diet, we assessed renal plasma flow. Renal plasma flow increase from restricted to liberal sodium diets was blunted in risk allele homozygotes in the total population and in hypertensives. A replication study in another cohort HyperPATH B (International Hypertension Pathotypes Cohort B) confirmed BP-genotype associations. CACNA1D rs7612148 risk allele associated with increased BP and salt sensitivity of BP, likely due to an impaired ability to increase renal plasma flow in response to a liberal sodium diet and not to excess aldosterone.

FRI157 Systematic Germline Genetic Analysis In A Cohort Of Adults With Primary Aldosteronism And Hypertension Onset ≤35 yo : Low Yield Of Genetic Pathogenic Variants

Abstract Disclosure: S. Parisien-La Salle: None. D. Nadine: None. Z. El-Haffaf: None. A. Lacroix: None. I. Bourdeau: None. Introduction: Primary aldosteronism (PA) is a common but underdiagnosed cause of hypertension. Although most cases are sporadic, up to 5% of patients have a familial form of PA. Current guidelines recommend germline genetic analysis in patients who present PA < 20 yo or have a family history of PA. As PA is underdiagnosed, we hypothesized that some patients with PA do not undergo germline genetic screening since familial history of PA is unrecognized. Objective: To evaluate the yield of systematic germline genetic analysis for familial PA in patients with PA, hypertension detection ≤ 35 yo and a family history of hypertension. Methods: From 2012-2022, patients diagnosed with PA (positive ARR and confirmatory testing), hypertension onset ≤ 35 yo and a family history of hypertension were offered genetic counselling for germline screening for known familial causes of PA. After informed consent, patients underwent germline analysis for the chimeric gene CYP11B2/CYP11B1 (Ruhr University Bochum, Germany) and a multigene panel including KCNJ5, CACNA1D, CACNA1H and CLCN2 genes (Fulgent, CA). Results: Twenty-five patients consented for genetic analysis. Thirteen patients (52%) were female. In regards to ethnic origin, 52% were French Canadians, 24% African-Americans and the other 24% was split between Asian, European and Middle Eastern descent. The mean age at diagnosis of hypertension was 28.3 yo and 39.7 yo at PA diagnosis. At PA diagnosis, 91.3% (21/23) had previous hypokalemia and 12% (3/25) a cortisol co-secretion (1 mg dexamethasone test> 50 nmol/L). Approximately 13% were on one hypertension drug, 30% on two, 26% on three, 26% on four and 5% were on five medications. Comobordities included: 8% atrial fibrillation, 20% obstructive sleep apnea and 4% coronary heart disease. All patients had a family history of hypertension, 5 patients (20%) had a family history of stroke, and 1 patient (4%) had a family history of PA. Of the patients who had already undergone adrenal vein sampling (n=22), 68.2% (15/22) underwent an adrenalectomy for lateralised aldosterone secretion and 31.8% (7/22) were treated with medical therapy for bilateral disease. None of the 24 patients who underwent testing for glucocorticoid-remediable aldosteronism were found to have the chimeric gene CYP11B2/CYP11B1. Twenty-three patients underwent the multigene panel and no pathogenic variants were identified. However, 4/23 (17,4%) patients carried a variant of unknown significance (VUS) in CACNA1H or CLCN2 genes (CACNA1H c.1315C>T(p.Arg439Cys),CACNA1H c.3868G>A(p.Val1290Ile),CACNA1H c.1939G>A (p.Gly647Ser), CLCN2 c.2402C>T, (p.Thr801Ile)). Conclusion: Systematic germline genetic testing for familial PA in this cohort of patients with PA, hypertension diagnosis ≤ 35 yo and a family history of hypertension did not yield positive results. Although PA is an underdiagnosed disease, familial forms remain very rare. Presentation: Friday, June 16, 2023

Analysis of genes related to female bone peak and osteoporosis based on bioinformatics

To explore and verify the genes related to female peak bone mass(PBM) and osteoporosis (OP) based on bioinformatics. Using GEO data, DNA microarray technology to conduct genome-wide analysis of adult female monocytes with high and low PBM. Cluster analysis, GO enrichment and KEGG analysis were used to analyze the differential genes, and the interaction network of differential genes was further analyzed. OP rat model was established and femur neck tissue staining was performed to further verify the expression of differential genes. A total of 283 genes were obtained by differential gene screening. Compared with the high PBM samples, 135 genes were up-regulated and 148 genes were down-regulated in the low PBM samples. A total of 7 pathways and 12 differential genes were enriched, and there were differences in the expression of several genes involved in mineral absorption and transport, cellular immunity and other aspects. Among them, voltage-gated Ca2+ channel 1.3(CaV1.3) encoded by CACNA1D gene was significantly enhanced in the femoral neck tissue of OP rat model. The above results suggest that the difference in the expression level of CaV1.3 gene may lead to the occurrence of OP in women with low PBM, which provides us with a potential target for the prevention and treatment of OP.

Brain α2δ-1-Bound NMDA Receptors Drive Calcineurin Inhibitor-Induced Hypertension.

Calcineurin is highly enriched in immune T cells and the nervous system. Calcineurin inhibitors, including cyclosporine and tacrolimus (FK506), are the cornerstone of immunosuppressive regimens for preserving transplanted organs and tissues. However, these drugs often cause persistent hypertension owing to excess sympathetic outflow, which is maintained by N-methyl-D-aspartate receptor (NMDAR)-mediated excitatory input to the hypothalamic paraventricular nucleus (PVN). It is unclear how calcineurin inhibitors increase NMDAR activity in the PVN to augment sympathetic vasomotor activity. α2δ-1 (encoded by the Cacna2d1 gene), known colloquially as a calcium channel subunit, is a newly discovered NMDAR-interacting protein. In this study, we determined whether α2δ-1 plays a role in calcineurin inhibitor-induced synaptic NMDAR hyperactivity in the PVN and hypertension development. Immunoblotting and coimmunoprecipitation assays were used to quantify synaptic protein levels and the physical interaction between GluN1 (the obligatory NMDAR subunit) and α2δ-1. Whole-cell patch-clamp recordings of retrogradely labeled, spinally projecting PVN were conducted in perfused brain slices to measure presynaptic and postsynaptic NMDAR activity. Radio-telemetry was implanted in rodents to continuously record arterial blood pressure in conscious states. Prolonged treatment with FK506 in rats significantly increased protein levels of α2δ-1, GluN1, and the α2δ-1-GluN1 complex in PVN synaptosomes. These effects were blocked by inhibiting α2δ-1 with gabapentin or interrupting the α2δ-1-NMDAR interaction with an α2δ-1 C-terminus peptide. Treatment with FK506 potentiated the activity of presynaptic and postsynaptic NMDARs in spinally projecting PVN neurons; such effects were abolished by gabapentin, Cacna2d1 knockout, or α2δ-1 C-terminus peptide. Furthermore, microinjection of α2δ-1 C-terminus peptide into the PVN diminished renal sympathetic nerve discharges and arterial blood pressure that had been increased by FK506 treatment. Remarkably, concurrent administration of gabapentin prevented the development of FK506-induced hypertension in rats. Additionally, FK506 treatment induced sustained hypertension in wild-type mice but not in Cacna2d1 knockout mice. α2δ-1 is essential for calcineurin inhibitor-induced increases in synaptic NMDAR activity in PVN presympathetic neurons and sympathetic outflow. Thus, α2δ-1 and α2δ-1-bound NMDARs represent new targets for treating calcineurin inhibitor-induced hypertension. Gabapentinoids (gabapentin and pregabalin) could be repurposed for treating calcineurin inhibitor-induced neurogenic hypertension.

The Relationship Between CACNA2D1 Gene and Subclinic Mastitis in Holstein Breed Cattle

The CACNA2D1 gene encodes the CACNA2D1 protein and, this protein is involved in the excitation-contraction mechanism of the muscle cells during milk withdrawal, helps the nipples to open and close. Because of this role in physiological mechanism and its relationship with quantitative trait locus (QTL) regions, CACNA2D1 gene is known to be associated with mastitis resistance. In this study, it was aimed to investigate the relationship between different three SNP (C367400T, A496561G and G519663A) on the CACNA2D1 gene, and subclinical mastitis in Holstein breed cattle reared in Develi district of Kayseri province. SNPs were genotyped from DNA samples by PCR-RFLP method. In the study, California mastitis test (CMT) data, and distributions of genotypes of the three SNPs on the CACNA2D1 gene were calculated. In the study, genotype distributions were determined in terms of C367400T, A496561G and G519663A SNPs found on the CACNA2D1 gene according to CMT status. The difference between the C367400T, A496561G and G519663A SNPs was not significant (p>0.05). In the study group examined the Chi-square (χ2) analysis conducted, it was observed that the Holstein cattle were in the Hardy-Weinberg equilibrium (HWE) in terms of C367400T and A496561G SNPs, deviation from HWE for the G519663A SNP (p<0.05). As a result, it was thought that the CACNA2D1 gene and these SNPs should be evaluated with more samples and different mastitis indicator data in studies on mastitis resistance.

Cigarette smoke triggers calcium overload in mouse hippocampal neurons via the ΔFOSB-CACNA2D1 axis to impair cognitive performance

A growing body of evidence shows that cigarette smoking impairs cognitive performance. The 'Calcium Hypothesis' theory of neuronopathies reveals a critical role of aberrant calcium signaling in compromised cognitive functions. However, the underlying implications of abnormalities in calcium signaling in the neurotoxicity induced by cigarette smoke (CS) have not yet been identified. CACNA2D1, an important auxiliary subunit involved in the composition of voltage-gated calcium channels (VGCCs), was reported to affect the calcium signaling in neurons by facilitating VGCCs-mediated Ca2+ influx. ΔFOSB, an alternatively-spliced product of the Fosb gene, is an activity-dependent transcription factor induced robustly in the brain in response to environmental stimuli such as CS. Interestingly, our preliminary bioinformatics analysis revealed a significant co-expression between ΔFOSB and CACNA2D1 in brain tissues of patients with neurodegenerative diseases characterized by progressive cognitive decline. Therefore, we hypothesized that the activation of the ΔFOSB-CACNA2D1 axis in response to CS exposure might cause dysregulation of calcium homeostasis in hippocampal neurons via VGCCs-mediated Ca2+ influx, thereby contributing to cognitive deficits. To this end, the present study established a CS-induced mouse model of hippocampus-dependent cognitive impairment, in which the activation of the ΔFOSB-CACNA2D1 axis accompanied by severe calcium overload was observed in the mouse hippocampal tissues. More importantly, ΔFOSB knockdown-/overexpression-mediated inactivation/activation of the ΔFOSB-CACNA2D1 axis interdicted/mimicked CS-induced dysregulation of calcium homeostasis followed by severe cellular damage in HT22 mouse hippocampal neurons. Mechanistically speaking, a further ChIP-qPCR assay confirmed the physical interaction between transcription factor ΔFOSB and the Cacna2d1 gene promoter, suggesting a direct transcriptional regulation of the Cacna2d1 gene by ΔFOSB. Overall, our current work aims to deliver a unique insight into the neurotoxic mechanisms induced by CS to explore potential targets for intervention.

The α2δ-1-NMDA receptor complex and its potential as a therapeutic target for ischemic stroke.

N-methyl-D-aspartate receptors (NMDARs) play a critical role in excitotoxicity caused by ischemic stroke, but NMDAR antagonists have failed to be translated into clinical practice for treating stroke patients. Recent studies suggest that targeting the specific protein-protein interactions that regulate NMDARs may be an effective strategy to reduce excitotoxicity associated with brain ischemia. α2δ-1 (encoded by the Cacna2d1 gene), previously known as a subunit of voltage-gated calcium channels, is a binding protein of gabapentinoids used clinically for treating chronic neuropathic pain and epilepsy. Recent studies indicate that α2δ-1 is an interacting protein of NMDARs and can promote synaptic trafficking and hyperactivity of NMDARs in neuropathic pain conditions. In this review, we highlight the newly identified roles of α2δ-1-mediated NMDAR activity in the gabapentinoid effects and NMDAR excitotoxicity during brain ischemia as well as targeting α2δ-1-bound NMDARs as a potential treatment for ischemic stroke.

Likely Pathogenic Variants of Cav1.3 and Nav1.1 Encoding Genes in Amyotrophic Lateral Sclerosis Could Elucidate the Dysregulated Pain Pathways.

Amyotrophic lateral sclerosis (ALS) is a lethal multisystem neurodegenerative disease associated with progressive loss of motor neurons, leading to death. Not only is the clinical picture of ALS heterogenous, but also the pain sensation due to different types of pain involvement. ALS used to be considered a painless disease, but research has been emerging and depicting a more complex pain representation in ALS. Pain has been detected even a couple years before the symptomatic stage of ALS, referring to primary pain associated with muscle denervation, although secondary pain due to nociceptive causes is also a part of the clinical picture. A new non-contact dying-back injury mechanism theory of ALS recently postulated that the irreversible intrafusal proprioceptive Piezo2 microinjury could be the primary damage, with underlying genetic and environmental risk factors. Moreover, this Piezo2 primary damage is also proposed to dysregulate the primary pain pathways in the spinal dorsal horn in ALS due to the lost imbalanced subthreshold Ca2+ currents, NMDA activation and lost L-type Ca2+ currents, leading to the lost activation of wide dynamic range neurons. Our investigation is the first to show that the likely pathogenic variants of the Cav1.3 encoding CACNA1D gene may play a role in ALS pathology and the associated dysregulation or loss of the pain sensation. Furthermore, our reanalysis also shows that the SCN1A gene might also contribute to the dysregulated pain sensation in ALS. Finally, the absence of pathogenic variants of Piezo2 points toward the new non-contact dying-back injury mechanism theory of ALS. However, molecular and genetic investigations are needed to identify the functionally diverse features of this proposed novel critical pathway.

PS-BPB06-10: DISTRIBUTION OF CACNA1D SOMATIC MUTATIONS AMONG CYP11B2 IMMUNOHISTOCHEMISTRY-GUIDED SAMPLES OF ALDOSTERONE-PRODUCING ADENOMA (APA)

Objectives: Past studies in Afro-Caribbean primary aldosteronism (PA) patients have found CACNA1D mutations to be the most common aldosterone-driving mutation among their cohort; a striking difference to Caucasian and Oriental cohorts where KCNJ5 mutations are reported to be the most common. However not many studies had used aldosterone synthase (CYP11B2) immunohistochemistry (IHC)-guided sequencing approach of the whole CACNA1D gene, performing instead unguided adenoma sampling and hotspot sequencing. We thus performed CYP11B2 IHC-guided whole gene sequencing on APAs from an Oriental cohort (Malaysia) and a Caucasian cohort (Czech Republic) for comparison. Design and method: Surgically removed adrenals from 100 Malaysian and Czech PA patients with unilateral disease were studied. Genomic DNA was isolated from adenoma FFPE sections that had a positive CYP11B2 IHC staining and somatic mutations analysis were performed by next generation sequencing (NGS) of known aldosterone-driver genes. Predicted pathogenic mutations were verified by Sanger Sequencing. Results: Out of 100 FFPE samples sent for NGS, 36 were excluded due to the quality of the data. In total 58 of 64 APAs (87.5%) had a pathogenic aldosterone-driver somatic mutation. KCNJ5 mutations were the most common (n = 37, 57.8%), followed by CACNA1D (n = 11, 20.3%), ATP1A1 (n = 6, 9.4%), ATP2B3 (n = 3, 4.7%) and CTNNB1 (n = 2, 3.1%) mutations. Of particular interest, one APA sample had two pathogenic somatic mutations, CACNA1D p.Val1373Met and CTNNB1: p.Thr41Ala. SIFT and Polyphen2 scores predicted both mutations to be deleterious. Both mutations have previously been reported separately to cause APAs. The CACNA1D/CTNNB1 mutant APA, was solitary, with homogeneous CYP11B2 expression while negative for CYP17A1 expression. The APA was adrenalectomized from a 53-year-old male Czech patient. The majority of patients with APAs harboring CACNA1D mutations were male (n = 8, 72.7%) and from the Czech cohort (n = 7, 64%). There were no significant differences in age at adrenalectomy between patients harboring a CACNA1D mutant APA (45 ± 3) and those with a non-CACNA1D mutant APA (48 ± 2). Conclusions: Solitary ZG APAs can harbor both a CACNA1D and a CTNNB1 mutation. The prevalence of CACNA1D in this CYP11B2-IHC guided study is consistent with previous results reported in Oriental and Caucasian cohorts. Although CACNA1D is not the top genetic alteration responsible for APAs in these cohorts, CACNA1D may still be a potential key player in idiopathic hyperaldosteronism and aldosterone-producing micronodules. Thus further study is required to characterize the distribution of CACNA1D pathogenic mutations in bilateral PA.