Subunit Of L-type Calcium Channel Research Articles

Landscape of extrachromosomal circular DNAs, transcriptome, and proteome analysis reveals insights into alcoholic liver cirrhosis

Alcoholic liver cirrhosis (ALC) is a result of excessive and chronic alcohol consumption. Because alchol can cause DNA damage, extrachromosomal circular DNA (eccDNA) was investigated in ALC liver due to it can be a result of DNA damage. Considering eccDNA has ability to lead to genomic instability as an enhancer of gene transcription, we utilized Circle-Seq to identify differences in eccDNA profiles and gene expression patterns in liver samples obtained from ALC patients (n = 3) and healthy controls (n = 3) to investigate the role of eccDNA in the development of ALC. The abundance of eccDNA in ALC (mean = 13,349) were higher than the healthy control (mean = 11,557) without significant difference (pvalue = 0.6530). We observed 1,032 eccDNA containing genes showed higher expression in ALC patients compared to healthy controls (p < 0.05, log2FC > 1). Notably, we discovered seven genes that exhibited a significant positive correlation between eccDNA abundance and gene expression levels. These genes include A disintegrin and metalloproteinase with thrombospondin motifs 2 (ADAMTS2), Voltage-dependent L-type calcium channel subunit alpha-1C (CACNA1C), Protein TANC1 (TANC1), Integrin alpha-2 (ITGA2), EH domain-containing protein 4 (EHD4), Phosphofurin acidic cluster sorting protein 1 (PACS1), and Neuron navigator 2 (NAV2). Through mass spectrometry proteomics, ITGA2 were found to have significantly higher abbudance in ALC. Integrins are a family of proteins plays key roles in the fibrosis development of liver. Thus, our study opens a new perspective for liver fibrosis development.

In silico Studies of Cilnidipine Degradation Products for Structure Confirmation, Toxicity Prediction and Molecular Docking

In this study, a comprehensive analysis of cilnidipine and its degradation products (KD1-KD4 and CD1-CD3) with three main objectives viz. (i) toxicity prediction for bacterial mutagenicity, (ii) assessment of pharmacological activity and (iii) density functional theory (DFT) calculations were performed for structure confirmation. For bacterial mutagenicity prediction, in silico assessments were performed following ICH M7 guidelines. Using rule-based and statistical-based methodologies, predictions revealed an alerting group in CD1-CD3, while no alerting group was observed in KD1-KD4 for bacterial mutagenicity. To assess pharmacological activity, docking studies were conducted to identify the mode of binding and interaction types of cilnidipine and its degradation products with N-type and L-type calcium channel subunits 7VFS and 7UHF, respectively. Additionally, 20 drugs acting as calcium channel blockers were considered for docking analysis to correlate the affinities of binding. The interaction energies revealed that molecule CD3 shows the highest binding affinity with the ligand molecules, with a binding energy of -9.2 (kcal/mol) with 7VFS and -8.7 (kcal/mol) with 7UHF proteins, followed by KD3 with a binding energy of -8.7 (kcal/mol) (7VFS) and -7.9 (kcal/mol) (7UHF). Furthermore, DFT calculations were employed to reassess the structures of degradation products CD1 and CD2 proposed in the literature. Simulating 1H and 13C NMR spectra, the obtained data demonstrated good agreement with experimental results, confirming the proposed stereo-configurations in the literature. Based on in silico bacterial mutagenicity predictions and docking studies, KD3 emerged as a promising compound for receptor binding. Additionally, DFT calculations provided structural insights, affirming stereo-configurations proposed in the existing literature. This multifaceted approach contributed valuable insights into the toxicity, pharmacology and structural aspects of cilnidipine degradation products.

Mineralocorticoid Receptors in Vascular Smooth Muscle: Blood Pressure and Beyond.

After half a century of evidence suggesting the existence of mineralocorticoid receptors (MR) in the vasculature, the advent of technology to specifically knockout the MR from smooth muscle cells (SMCs) in mice has elucidated contributions of SMC-MR to cardiovascular function and disease, independent of the kidney. This review summarizes the latest understanding of the molecular mechanisms by which SMC-MR contributes to (1) regulation of vasomotor function and blood pressure to contribute to systemic and pulmonary hypertension; (2) vascular remodeling in response to hypertension, vascular injury, obesity, and aging, and the impact on vascular calcification; and (3) cardiovascular pathologies including aortic aneurysm, heart valve dysfunction, and heart failure. Data are reviewed from in vitro studies using SMCs and in vivo findings from SMC-specific MR-knockout mice that implicate target genes and signaling pathways downstream of SMC-MR. By regulating expression of the L-type calcium channel subunit Cav1.2 and angiotensin II type-1 receptor, SMC-MR contributes to myogenic tone and vasoconstriction, thereby contributing to systemic blood pressure. MR activation also promotes SMC proliferation, migration, production and degradation of extracellular matrix, and osteogenic differentiation by regulating target genes including connective tissue growth factor, osteopontin, bone morphogenetic protein 2, galectin-3, and matrix metallopeptidase-2. By these mechanisms, SMC-MR promotes disease progression in models of aging-associated vascular stiffness, vascular calcification, mitral and aortic valve disease, pulmonary hypertension, and heart failure. While rarely tested, when sexes were compared, the mechanisms of SMC-MR-mediated disease were sexually dimorphic. These advances support targeting SMC-MR-mediated mechanisms to prevent and treat diverse cardiovascular disorders.

Amlodipine inhibits the proliferation and migration of esophageal carcinoma cells through the induction of endoplasmic reticulum stress.

L-type calcium channels are the only protein channels sensitive to calcium channel blockers, and are expressed in various cancer types. The Cancer Genome Atlas database shows that the mRNA levels of multiple L-type calcium channel subunits in esophageal squamous cell carcinoma tumor tissue are significantly higher than those in normal esophageal epithelial tissue. Therefore, we hypothesized that amlodipine, a long-acting dihydropyridine L-type calcium channel blocker, may inhibit the occurrence and development of esophageal cancer (EC). To investigate the inhibitory effects of amlodipine on EC through endoplasmic reticulum (ER) stress. Cav1.3 protein expression levels in 50 pairs of EC tissues and corresponding paracancerous tissues were examined. Subsequently, the inhibitory effects of amlodipine on proliferation and migration of EC cells in vitro were detected using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and Transwell assays. In vivo experiments were performed using murine xenograft model. To elucidate the underlying mechanisms, in vitro cell studies were performed to confirm that ER stress plays a role in inhibition proliferation and migration of EC cells treated with amlodipine. The expression level of Cav1.3 in esophageal carcinoma was 1.6 times higher than that in paracancerous tissues. Amlodipine treatment decreased the viability of esophageal carcinoma cells in a dose- and time-dependent manner. In vivo animal experiments also clearly indicated that amlodipine inhibited the growth of EC tumors in mice. Additionally, amlodipine reduces the migration of tumor cells by inhibiting epithelial-mesenchymal transition (EMT). Mechanistic studies have demonstrated that amlodipine induces ER stress-mediated apoptosis and suppresses EMT. Moreover, amlodipine-induced autophagy was characterized by an increase in autophagy lysosomes and the accumulation of light chain 3B protein. The combination of amlodipine with the ER stress inhibitor 4-phenylbutyric acid further confirmed the role of the ER stress response in amlodipine-induced apoptosis, EMT, and autophagy. Furthermore, blocking autophagy increases the ratio of apoptosis and migration. Collectively, we demonstrate for the first time that amlodipine promotes apoptosis, induces autophagy, and inhibits migration through ER stress, thereby exerting anti-tumor effects in EC.

Potential application of bisoprolol derivative compounds as antihypertensive drugs: synthesis and in silico study.

Two bisoprolol derivatives, N-acetyl bisoprolol and N-formyl bisoprolol, belonging to the beta-blocker class of antihypertensive drugs, were synthesized using acetylation and formylation reactions. The yields of the reactions were determined to be 32.40% for N-acetyl bisoprolol and 20.20% for N-formyl bisoprolol. In silico methods such as molecular docking, molecular dynamics simulation and SwissADME prediction were employed to evaluate the potential of these bisoprolol derivatives as antihypertensive drugs. These methods were used to assess the interaction between the bisoprolol derivatives and various receptors associated with hypertension, including human angiotensin I-converting enzyme (PDB ID: 1O8A), renin (PDB ID: 2V0Z), beta-1 adrenergic receptors (PDB ID: 4BVN, 7BVQ), voltage-dependent L-type calcium channel subunit alpha-1S (PDB ID: 6JP5) and mineralocorticoid receptor (PDB ID: 6L88). Our results demonstrated the highest binding energy when bisoprolol and its derivatives bound to 4BVN, with binding energy values of 6.74 kcal mol-1, 7.03 kcal mol-1 and 7.63 kcal mol-1 for bisoprolol, N-acetyl bisoprolol and N-formyl bisoprolol, respectively. The stability of these complexes was confirmed by molecular dynamics simulations, with a root-mean-square deviation value of approximately 2. Furthermore, the SwissADME results indicated that both derivatives exhibited similar properties to the reference drug bisoprolol.

Effect of semaglutide and empagliflozin on cognitive function and hippocampal phosphoproteomic in obese mice.

Objective: Based on the 4D label-free phosphoproteomic technique, we examined the differences in cognitive function and hippocampal phosphorylated protein expression in high-fat diet-induced obese mice after the intervention of semaglutide and empagliflozin, as well as the effects of both on protein activity and function in obese mice's hippocampal tissues and the signaling pathways involved. Methods: Thirty-two C57BL/6JC male mice were assigned to two groups randomly: A control group (group C, 10% of energy is from fat, n = 8) and a high-fat diet group (group H, 60% of energy is from fat, n = 24). The high-fat diet-induced obese mice were screened after 12weeks of feeding based on the criterion that the bodyweight of mice in fat rich diet group was greater than or equal to 20% of the average body weight of the mice in the blank control group. Group H separate into group H (n = 8), group Semaglutide (group S, n = 8), and group empagliflozin (group E, n = 8). For a total of 12weeks, group S received 30nmol/kg/d bodyweight of semaglutide intraperitoneally, group E received 10mg/kg/d bodyweight of empagliflozin via gavage, and groups C and H received equal amounts of saline by intraperitoneal injection and gavage. At the end of treatment, the mice were appraised for cognitive function employing the Morris water maze (MWM), and serum fasting glucose, lipids, and inflammatory parameters were measured. The 4D label-free phosphoproteomics method was employed to screen the differential phosphoproteins and loci in hippocampal tissues of mice in different treatment groups, and bioinformatics was used to analyze the biological processes, signaling pathways, and related protein-protein interaction (PPI) network analysis of these differentially phosphorylated proteins. Results: In comparison to normal controls, The escape latency of obese mice induced by high-fat diet was prolonged, the percentage of swimming time in the target quadrant was reduced, and the number of times of crossing the platform was reduced, whereas semaglutide and empagliflozin treatment reduced escape latency, increase the percentage of swim time in the target quadrant and increase the frequency of passing through the platform area, although there is little difference in the effect of the two drugs. The phosphoproteomic results showed 20,493 unique phosphorylated peptides, representing 21,239 phosphorylation sites and 4,290 phosphorylated proteins. Further analysis revealed that the proteins corresponding to these differentially phosphorylated sites are jointly distributed in signaling pathways such as dopaminergic synapses and axon guidance, and are involved in biological processes such as neuronal projection development, synaptic plasticity, and axonogenesis. Notably, the key factors voltage-dependent L-type calcium channel subunit alpha-1D (CACNA1D), voltage-dependent P/Q-type calcium channel subunit alpha-1A (CACNA1A), and voltage-dependent N-type calcium channel subunit alpha-1B (CACNA1B) were all found to be involved in the dopaminergic synapse pathway, and their expression was upregulated by semaglutide and empagliflozin. Conclusion: We found for the first time that a high-fat diet decreased CACNA1D, CACNA1A, and CACNA1B protein serine phosphorylation, which may affect neuronal development, synaptic plasticity, and cognitive function in mice. Notably, semaglutide and empagliflozin increased the phosphorylation of these proteins.

L‐Type calcium channel antagonist isradipine decreases area of plaque associated dystrophic neurites in 5XFAD mouse model

AbstractBackgroundEpidemiological studies suggest that L‐type calcium channel (LTCC) antagonists may reduce the incidence of neurodegenerative diseases including Alzheimer’s disease (AD). However, the neuroprotective mechanism of LTCC antagonists is unknown. Amyloid‐β (aβ) increases intracellular calcium signaling, which regulates lysosomal processing and microglial inflammatory responses, both of which are altered in AD. Neurons near aβ plaques develop dystrophic neurites, which are abnormal axonal swellings that accumulate lysosomes. Further, microglia accumulate around aβ plaques and secrete inflammatory cytokines. We hypothesized that antagonism of LTCCs with isradipine would reduce aβ plaque associated dystrophic neurites and inflammatory microglia in the 5XFAD mouse model of AD by restoring normal intracellular calcium regulation.MethodWe treated 6‐ and 9‐month‐old 5XFAD mice with isradipine (3 mg/kg/day) or vehicle via subcutaneous pellets for 30 days. Following three weeks of treatment we tested locomotion and cognitive behavior via open field, novel object recognition and Morris water maze. We measured gene expression of inflammatory mediators (IL1β, TNF, CD68) and LTCC subunits (Cav1.2, Cav1.3) using qPCR. Using immunohistochemistry (IHC), we examined aβ plaque number and area (D54D2 and ThioS), microglia area (Iba1), dystrophic neurites area and particle number (LAMP1) normalized to total brain area.ResultIHC revealed that isradipine treatment in 9‐month‐old 5XFADs decreased the total area of LAMP1 positive dystrophic neurites (p = 0.0310) compared to vehicle‐treated 5XFADs; this change was not observed in the 6‐month‐old group. Isradipine treatment in the 9‐month‐old 5XFADs also led to a decreasing trend (p = 0.0552) in plaque load compared to vehicle‐treated 5xFADs as measured by IHC. Isradipine treatment did not modulate plaque associated microglia as measured by IHC or inflammatory gene expression as measured by qPCR, regardless of age. There was no treatment effect on behavior or expression of LTCC subunits.ConclusionOur data show that isradipine reduces aβ plaque associated dystrophic neurite pathology in 9‐month‐old 5XFAD mice, potentially showing LTCC play a role in mediating this specific phenotype. Our future studies will focus on understanding why antagonizing LTCCs leads to a decrease in LAMP1 and whether this is due to changes in lysosomal development and processing or other possible mechanisms.

Epigenetic mechanism of L-type calcium channel β-subunit downregulation in short QT human induced pluripotent stem cell-derived cardiomyocytes with CACNB2 mutation.

A loss-of-function mutation in L-type calcium (Ca2+) channel subunit gene CACNB2 has been reported to cause short QT syndrome subtype 5 (SQT5). However, the mechanism underlying the loss-of-function of the Ca2+ channel has not been clarified. In the present study, we aim to explore the DNA methylation mechanism of L-type Ca2+ channel downregulation in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) of SQT5. The hiPSC-CMs were generated from a healthy donor and a SQT5 patient carrying the CACNB2 variant c.1439C > T/p.S480L. The variant was genetically corrected using ribonucleoprotein-based CRISPR/Cas9 technique to obtain an isogenic control cell line. The action potential (AP) and Ca2+ current were measured by patch clamp. Protein expression levels were determined by western blotting. Dot blotting and bisulfite sequence were performed for epigenetic study. Our results showed that AP durations at 10% repolarization (APD10) and 50% repolarization (APD50) were significantly shortened in SQT5 cells and both the expression level of the β-subunit and channel current of L-type Ca2+ channel were reduced. Besides, an increased level of whole-genome DNA methylation and DNA methylation of CpG island in the promoter region of CACNB2 gene was detected. Overexpression of demethylation enzyme could rescue the decreased expression of CACNB2 and the L-type Ca2+ current. In SQT5 hiPSC-CMs carrying the CACNB2-S480L variant, the decreased L-type Ca2+ current resulting from decreased CACNB2 protein expression was caused by enhanced methylation in the promoter region of the CACNB2 gene and upregulation of DNA methyltransferases might be one of the mechanisms.

Abnormal levels of mitochondrial Ca2+ channel proteins in plasma neuron-derived extracellular vesicles of early schizophrenia.

Structural alterations or quantitative abnormalities of some mitochondrial ion channels and exchangers are associated with altered neuronal functions and increased susceptibility to mental illness. Here we have assessed levels of functionally prominent mitochondrial calcium ion channel proteins in plasma neuron-derived extracellular vesicles (NDEVs) of living patients with first episodes of psychosis (FP) and matched controls (Cs). NDEVs were enriched with an established method of precipitation and immunoabsorption by anti-human CD171 neural adhesion protein (L1CAM) antibody and extracted proteins quantified with ELISAs. CD81 exosome marker-normalized NDEV levels of leucine zipper EF-hand containing transmembrane 1 protein (LETM1), transient receptor potential cation channel subfamily M, member 4 (TRPM4), and solute carrier family 8 member B1 (SLC24A6) or mitochondrial Na+ /Ca2+ exchanger (NCLX) were significantly lower for FP patients (n=10) than Cs (n=10), whereas NDEV levels of voltage-dependent L-type calcium channel subunit α-1C (CACNA-1C) were significantly higher for FP patients than Cs. Abnormal structures or mitochondrial levels of LETM1, NCLX, and CACNA-1C have been linked through analyses of individual proteins, genome-wide association studies, and whole exome protein-coding sequence studies to neurodevelopmental disorders, mental retardation, schizophrenia, and major depressive diseases. A greater understanding of the altered calcium homeostasis in schizophrenia, that is attributable to underlying mitochondrial calcium channel abnormalities, will lead to improved diagnosis and treatment.

Gene Dysregulation in the Adult Rat Paraventricular Nucleus and Amygdala by Prenatal Exposure to Dexamethasone.

Fetal programming is the concept that maternal stressors during critical periods of fetal development can alter offspring phenotypes postnatally. Excess glucocorticoids can interact with the fetus to effect genetic and epigenetic changes implicated in adverse developmental outcomes. The present study investigates how chronic exposure to the synthetic glucocorticoid dexamethasone during late gestation alters the expression of genes related to behavior in brain areas relevant to the regulation and function of the hypothalamic–pituitary–adrenal axis. Pregnant Wistar Kyoto rats received subcutaneous injections of dexamethasone (100 μg/kg) daily from gestational day 15–21 or vehicle only as sham controls. The amygdala and paraventricular nucleus (PVN) were micro-punched to extract mRNA for reverse transcription and quantitative polymerase chain reaction for the analysis of the expression of specific genes. In the PVN, the expression of the glucocorticoid receptor NR3C1 was downregulated in female rats in response to programming. The expression of CACNA1C encoding the Cav1.2 pore subunit of L-type voltage-gated calcium channels was downregulated in male and female rats prenatally exposed to dexamethasone. Collectively, the results suggest that prenatal exposure to elevated levels of glucocorticoids plays a role in the dysregulation of the hypothalamic–pituitary–adrenal axis and potentially learning and memory by altering the expression of specific genes within the amygdala and PVN.

Solanaceae glycoalkaloids: α-solanine and α-chaconine modify the cardioinhibitory activity of verapamil

Context Solanaceae glycoalkaloids (SGAs) possess cardiomodulatory activity. Objective This study investigated the potential interaction between verapamil and glycoalkaloids. Material and methods The cardioactivity of verapamil and glycoalkaloids (α-solanine and α-chaconine) was tested in adult beetle (Tenebrio molitor) myocardium in vitro using microdensitometric methods. The myocardium was treated with pure substances and mixtures of verapamil and glycoalkaloids for 9 min with saline as a control. Two experimental variants were used: simultaneous application of verapamil and glycoalkaloids or preincubation of the myocardium with one of the compounds followed by perfusion with a verapamil solution. We used 9 × 10−6–5 × 10−5 M and 10−9–10−5 M concentration for verapamil and glycoalkaloids, respectively. Results Verapamil, α-solanine and α-chaconine showed cardioinhibitory activity with IC50 values equal to 1.69 × 10−5, 1.88 × 10−7 and 7.48 × 10−7 M, respectively. When the glycoalkaloids were applied simultaneously with verapamil, an antagonistic effect was observed with a decrease in the maximal inhibitory effect and prolongation of t50 and the recovery time characteristic of verapamil. We also confirmed the expression of two transcript forms of the gene that encodes the α1 subunit of L-type calcium channels in the myocardium and brain with equal transcription levels of both forms in the myocardium and significant domination of the shorter form in the brain of the insect species tested. Discussion and conclusions The results show that attention to the composition of the daily diet during therapy with various drugs is particularly important. In subsequent studies, the nature of interaction between verapamil and SGAs on the molecular level should be checked, and whether this interaction decreases the efficiency of cardiovascular therapy with verapamil in humans.

Mitchell-Riley Syndrome: Improving Clinical Outcomes and Searching for Functional Impact of RFX-6 Mutations.

Aims/HypothesisCaused by biallelic mutations of the gene encoding the transcription factor RFX6, the rare Mitchell–Riley syndrome (MRS) comprises neonatal diabetes, pancreatic hypoplasia, gallbladder agenesis or hypoplasia, duodenal atresia, and severe chronic diarrhea. So far, sixteen cases have been reported, all with a poor prognosis. This study discusses the multidisciplinary intensive clinical management of 4 new cases of MRS that survived over the first 2 years of life. Moreover, it demonstrates how the mutations impair the RFX6 function.MethodsClinical records were analyzed and described in detail. The functional impact of two RFX6R181W and RFX6V506G variants was assessed by measuring their ability to transactivate insulin transcription and genes that encode the L-type calcium channels required for normal pancreatic beta-cell function.ResultsAll four patients were small for gestational age (SGA) and prenatally diagnosed with duodenal atresia. They presented with neonatal diabetes early in life and were treated with intravenous insulin therapy before switching to subcutaneous insulin pump therapy. All patients faced recurrent hypoglycemic episodes, exacerbated when parenteral nutrition (PN) was disconnected. A sensor-augmented insulin pump therapy with a predictive low-glucose suspension system was installed with good results. One patient had a homozygous c.1517T>G (p.Val506Gly) mutation, two patients had a homozygous p.Arg181Trp mutation, and one patient presented with new compound heterozygosity. The RFX6V506G and RFX6R181W mutations failed to transactivate the expression of insulin and genes that encode L-type calcium channel subunits required for normal pancreatic beta-cell function.Conclusions/InterpretationMultidisciplinary and intensive disease management improved the clinical outcomes in four patients with MRS, including adjustment of parenteral/oral nutrition progression and advanced diabetes technologies. A better understanding of RFX6 function, in both intestine and pancreas cells, may break ground in new therapies, particularly regarding the use of drugs that modulate the enteroendocrine system.

Identification of ultra-rare disruptive variants in voltage-gated calcium channel-encoding genes in Japanese samples of schizophrenia and autism spectrum disorder

Several large-scale whole-exome sequencing studies in patients with schizophrenia (SCZ) and autism spectrum disorder (ASD) have identified rare variants with modest or strong effect size as genetic risk factors. Dysregulation of cellular calcium homeostasis might be involved in SCZ/ASD pathogenesis, and genes encoding L-type voltage-gated calcium channel (VGCC) subunits Cav1.1 (CACNA1S), Cav1.2 (CACNA1C), Cav1.3 (CACNA1D), and T-type VGCC subunit Cav3.3 (CACNA1I) recently were identified as risk loci for psychiatric disorders. We performed a screening study, using the Ion Torrent Personal Genome Machine (PGM), of exon regions of these four candidate genes (CACNA1C, CACNA1D, CACNA1S, CACNA1I) in 370 Japanese patients with SCZ and 192 with ASD. Variant filtering was applied to identify biologically relevant mutations that were not registered in the dbSNP database or that have a minor allele frequency of less than 1% in East-Asian samples from databases; and are potentially disruptive, including nonsense, frameshift, canonical splicing site single nucleotide variants (SNVs), and non-synonymous SNVs predicted as damaging by five different in silico analyses. Each of these filtered mutations were confirmed by Sanger sequencing. If parental samples were available, segregation analysis was employed for measuring the inheritance pattern. Using our filter, we discovered one nonsense SNV (p.C1451* in CACNA1D), one de novo SNV (p.A36V in CACNA1C), one rare short deletion (p.E1675del in CACNA1D), and 14 NSstrict SNVs (non-synonymous SNV predicted as damaging by all of five in silico analyses). Neither p.A36V in CACNA1C nor p.C1451* in CACNA1D were found in 1871 SCZ cases, 380 ASD cases, or 1916 healthy controls in the independent sample set, suggesting that these SNVs might be ultra-rare SNVs in the Japanese population. The neuronal splicing isoform of Cav1.2 with the p.A36V mutation, discovered in the present study, showed reduced Ca2+-dependent inhibition, resulting in excessive Ca2+ entry through the mutant channel. These results suggested that this de novo SNV in CACNA1C might predispose to SCZ by affecting Ca2+ homeostasis. Thus, our analysis successfully identified several ultra-rare and potentially disruptive gene variants, lending partial support to the hypothesis that VGCC-encoding genes may contribute to the risk of SCZ/ASD.

BDNF Levels According to Variations in the CACNA1C Gene: Sex-Based Disparity.

The CACNA1C gene encodes the pore-forming alpha-1c subunit of L-type voltage-gated calcium channels. The calcium influx through these channels regulates the transcription of the brain-derived neurotrophic factor (BDNF). Polymorphisms in this gene have been consistently associated with psychiatric disorders, and alterations in BDNF levels are a possible biological mechanism to explain such associations. Here, we sought to investigate the effect of the CACNA1C rs1006737 and rs4765913 polymorphisms and their haplotypes on serum BDNF concentration. We further aim to investigate the regulatory function of these SNPs and the ones linked to them. The study enrolled 641 young adults (362 women and 279 men) in a cross-sectional population-based survey. Linear regression was used to test the effects of polymorphisms and haplotypes on BDNF levels adjusted for potential confounders. Moreover, regulatory putative functional roles were assessed using in silico approach. BDNF levels were not associated with CACNA1C polymorphisms/haplotype in the total sample. When the sample was stratified by sex, checking the effect of polymorphisms on men and women separately, the A-allele of rs4765913 was associated with lower BDNF levels in women compared with the TT genotype (p = 0.010). The AA (rs1006737-rs4765913) haplotype was associated with BDNF levels in opposite directions regarding sex, with lower levels of BDNF in women (p = 0.040) compared to those without this haplotype, while with higher levels in men (p = 0.027). These findings were supported by the presence of regulatory marks only on the male fetal brain. Our results suggest that the BDNF levels regulation may be a potential mechanism underpinning the association between CACNA1C and psychiatric disorders, with a differential role in women and men.

Lrrc10 is a versatile modulator of cardiac four-domain voltage-gated channels

Cardiac L-type calcium channels (LTCC) and their modulation figure crucially in the normal function and pathophysiology of the heart. These channels convey calcium influx that shapes the cardiac action potential, initiates excitation-contraction coupling, and supports inotropy. To fulfill its function, LTCC activity is tuned by multiple regulatory proteins, including well-established auxiliary subunits and non-canonical modulators. In this context, leucine-rich repeat containing protein 10 (Lrrc10), a cardiac-specific protein, has emerged as a non-canonical subunit of LTCC.

Validating the Significance of Ser1487 in the Beta-Adrenergic Regulation of the Alpha Subunit of the Cardiac L-Type Calcium Channel Using a CRISPR/Cas9 Mouse Model

Beta-adrenergic receptor stimulation increases calcium influx through the pore forming alpha subunit of the cardiac L-type Ca2+ channel (CaV1.2). Chronic activation of the CaV1.2 can lead to development of cardiac hypertrophy and arrhythmia formation; yet the molecular mechanism remains unresolved.

Adaptive Mechanisms of Somatostatin-Positive Interneurons after Traumatic Brain Injury through a Switch of α Subunits in L-Type Voltage-Gated Calcium Channels.

Unilateral traumatic brain injury (TBI) causes cortical dysfunctions spreading to the primarily undamaged hemisphere. This phenomenon, called transhemispheric diaschisis, is mediated by an imbalance of glutamatergic versus GABAergic neurotransmission. This study investigated the role of GABAergic, somatostatin-positive (SST) interneurons in the contralateral hemisphere 72h after unilateral TBI. The brain injury was induced to the primary motor/somatosensory cortex of glutamate decarboxylase 67-green fluorescent protein (GAD67-GFP) knock-in mice at postnatal days 19-21 under anesthesia in vivo. Single GFP+ interneurons of the undamaged, contralateral cortex were isolated by fluorescence-activated cell sorting and analyzed by mass spectrometry. TBI caused a switch of 2 α subunits of pore-forming L-type voltage-gated calcium channels (VGCC) in GABAergic interneurons, an increased expression of CaV1.3, and simultaneous ablation of CaV1.2. This switch was associated with 1) increased excitability of single SST interneurons in patch-clamp recordings and (2) a recovery from early network hyperactivity in the contralateral hemisphere in microelectrode array recordings of acute slices. The electrophysiological changes were sensitive to pharmacological blockade of CaV1.3 (isradipine, 100nM). These data identify a switch of 2 α subunits of VGCCs in SST interneurons early after TBI as a mechanism to counterbalance post-traumatic hyperexcitability.

Rapid Repurposing of Novel Combination Drugs for the Treatment of Heart Failure via a Computationally Guided Network Screening Approach.

Combination drugs, characterized by high efficacy and few side effects, have received extensive attention from pharmaceutical companies and researchers for the treatment of complex diseases such as heart failure (HF). Traditional combination drug discovery depends on large-scale high-throughput experimental approaches that are time-consuming and costly. Herein we developed a novel, rapid, and potentially universal computer-guided combination drug-network-screening approach based on a set of databases and web services that are easy for individuals to obtain and operate, and we discovered for the first time that the menthol-allethrin combination screened by this approach exhibited a significant synergistic cardioprotective effect in vitro. Further mechanistic studies indicated that allethrin and menthol could synergistically block calcium channels. Allethrin bound to the central cavity of the voltage-dependent L-type calcium channel subunit alpha-1S (CACNA1S) lead to a conformational change in an allosteric site of CACNA1S, thereby enhancing the binding of menthol to this allosteric site. In summary, we reported a potentially universal computational approach to combination drug screening that has been used to discover a new combination of menthol-allethrin against HF in vitro, providing a new synergistic mechanism and prospective agent for HF treatment.

Zika E Glycan Loop Region and Guillain-Barré Syndrome-Related Proteins: A Possible Molecular Mimicry to Be Taken in Account for Vaccine Development.

The neurological complications of infection by the mosquito-borne Zika virus (ZIKV) include Guillain–Barré syndrome (GBS), an acute inflammatory demyelinating polyneuritis. GBS was first associated with recent ZIKV epidemics caused by the emergence of the ZIKV Asian lineage in South Pacific. Here, we hypothesize that ZIKV-associated GBS relates to a molecular mimicry between viral envelope E (E) protein and neural proteins involved in GBS. The analysis of the ZIKV epidemic strains showed that the glycan loop (GL) region of the E protein includes an IVNDT motif which is conserved in voltage-dependent L-type calcium channel subunit alpha-1C (Cav1.2) and Heat Shock 70 kDa protein 12A (HSP70 12A). Both VSCC-alpha 1C and HSP70 12A belong to protein families which have been associated with neurological autoimmune diseases in central nervous system. The purpose of our in silico analysis is to point out that IVNDT motif of ZIKV E-GL region should be taken in consideration for the development of safe and effective anti-Zika vaccines by precluding the possibility of adverse neurologic events including autoimmune diseases such as GBS through a potent mimicry with Heat Shock 70 kDa protein 12A (HSP70 12A).

Effect of Gabapentin in a Neuropathic Pain Model in Mice Overexpressing Human Wild-Type or Human Mutated Torsin A.

Background: DYT1 dystonia is the most common form of early-onset inherited dystonia, which is caused by mutation of torsin A (TA) belonging to the “ATPases associated with a variety of cellular activities” (AAA + ATPase). Dystonia is often accompanied by pain, and neuropathic pain can be associated to peripherally induced movement disorder and dystonia. However, no evidence exists on the effect of gabapentin in mice subjected to neuropathic pain model overexpressing human normal or mutated TA. Methods: Mice subjected to L5 spinal nerve ligation (SNL) develop mechanical allodynia and upregulation of the α2δ-1 L-type calcium channel subunit, forming a validated experimental model of neuropathic pain. Under these experimental conditions, TA is expressed in dorsal horn neurons and astrocytes and colocalizes with α2δ-1. Similar to this subunit, TA is overexpressed in dorsal horn 7 days after SNL. This model has been used to investigate (1) basal mechanical sensitivity; (2) neuropathic pain phases; and (3) the effect of gabapentin, an α2δ-1 ligand used against neuropathic pain, in non-transgenic (NT) C57BL/6 mice and in mice overexpressing human wild-type (hWT) or mutant (hMT) TA. Results: In comparison to non-transgenic mice, the threshold for mechanical sensitivity in hWT or hMT does not differ (Kruskal–Wallis test = 1.478; p = 0.4777, although, in the latter animals, neuropathic pain recovery phase is delayed. Interestingly, gabapentin (100 mg/Kg) reduces allodynia at its peak (occurring between post-operative day 7 and day 10) but not in the phase of recovery. Conclusions: These data lend support to the investigation on the role of TA in the molecular machinery engaged during neuropathic pain.