Subunit Of Voltage-gated Calcium Channels Research Articles

Impacts of CACNB4 overexpression on dendritic spine density in both sexes and relevance to schizophrenia

The voltage-gated calcium channel (VGCC) subunit complex is comprised of the α1 subunit, the ion-permeable channel, and three auxiliary subunits: β, α2δ, and γ. β is the most extensively studied auxiliary subunit and is necessary for forward trafficking of the α1 subunit to the plasma membrane. VGCCs mediate voltage-dependent movement of calcium ions into neuronal cytoplasm, including at dendrites, where intracellular calcium spikes initiate signaling cascades that shape the structural plasticity of dendritic spines. Genetic studies strongly implicate calcium signaling dysfunction in the etiology of neurodevelopmental disorders including schizophrenia. Dendritic spine density is significantly decreased in schizophrenia in the primary auditory cortex where it is driven by the loss of small spines, and small spine loss associated with increased peptide levels of ALFDFLK found in the VGCC β subunit β4. Overexpressing the gene that encodes the voltage-gated calcium channel subunit β4, CACNB4, selectively reduced small spine density in vitro. In the current study we extended this observation in an intact mammalian system within a relevant neurodevelopmental context. We overexpressed CACNB4 in early development, assessed spine density and morphology in adult male and female mouse cortex, and characterized β1-4 protein levels and β4 protein-protein interactions. Overexpression reduced small spine density in females. This effect was not dependent on the estrous stage. Instead, it corresponded to sex differences in the murine β4 interactome. The VGCC subunit β1b was significantly enriched in the β4 interactome of male relative to female mice, and thus may have served to mitigate VGCC overexpression-mediated spine loss in male mice.

The VGCC auxiliary subunit α2δ1 is an extracellular GluA1 interactor and regulates LTP, spatial memory, and seizure susceptibility.

Activity-dependent synaptic accumulation of AMPA receptors (AMPARs) and subsequent long-term synaptic strengthening underlie different forms of learning and memory. The AMPAR subunit GluA1 amino-terminal domain is essential for synaptic docking of AMPAR during LTP, but the precise mechanisms involved are not fully understood. Using unbiased proteomics, we identified the epilepsy and intellectual disability-associated VGCC auxiliary subunit α2δ1 as a candidate extracellular AMPAR slot. Presynaptic α2δ1 deletion in CA3 affects synaptic AMPAR incorporation during long-term potentiation, but not basal synaptic transmission, at CA1 synapses. Consistently, mice lacking α2δ1 in CA3 display a specific impairment in CA1-dependent spatial memory, but not in memory tests involving other cortical regions. Decreased seizure susceptibility in mice lacking α2δ1 in CA3 suggests a regulation of circuit excitability by α2δ1/AMPAR interactions. Our study sheds light on the regulation of activity-dependent AMPAR trafficking, and highlights the synaptic organizing roles of α2δ1.

Pregabalin produces analgesia in males but not females in an animal model of chronic widespread muscle pain.

Pregabalin, which acts on the α2δ-1 subunit of voltage-gated calcium channels, relieves ≥50% of pain in a third of individuals with fibromyalgia. Thus far, preclinical studies of pregabalin have predominantly used male animals. The purpose of our study was to investigate potential sex differences in the analgesic efficacy of pregabalin that may contribute to disparities in human outcomes. We used a mouse model of chronic widespread muscle pain (CWP) to test the effects of pregabalin on muscle hyperalgesia, nonreflexive pain, and motor behaviors. The CWP pain model combines 2 pH 4.0 saline injections, spaced 5 days apart, into the gastrocnemius muscle and produces bilateral muscle hyperalgesia. Furthermore, we explored sex differences in the mRNA and protein expression of the α2δ-1 subunit of voltage-gated calcium channels in the dorsal horn of the spinal cord and dorsal root ganglia after development of CWP. Pregabalin fully attenuated muscle hyperalgesia bilaterally in male but not female mice with equal motor deficits produced in both sexes. In addition, using the conditioned place preference test, mice of both sexes with CWP spent significantly more time in the pregabalin-paired chamber compared with baseline, but not significantly greater than pain-free controls. Chronic widespread muscle pain produced no changes in α2δ-1 subunit mRNA or protein expression in the dorsal horn of the spinal cord or dorsal root ganglia in either sex. Overall, these findings indicate pregabalin may be more effective in treating CWP in males, but the factors leading to these differences are not fully understood.

Molecular dynamics exploration of cacophony protein interactions with brood volatiles in honey bee colonies

The cacophony protein is a key component of honey bee biology that has been investigated concerning hygienic behavior. The voltage-gated calcium channel subunit α1 appears to play a significant role in modulating neuronal activity associated with the detection and response to compromised brood within honey bee colonies. Despite its essential role, the molecular mechanisms underpinning hygienic behavior remain incompletely understood. Recent research suggests that the expression of the cacophony protein is linked to the efficiency of hygienic behavior, where colonies with enhanced hygienic behavior exhibit distinct patterns of cacophony expression. Understanding the role of cacophony in honey bee behavior provides insights into the molecular mechanisms underlying social interactions within bee colonies, with implications for enhancing pollination services and mitigating threats to honey bee populations. Therefore, the present study focused on unraveling and characterizing its structure and function, using bioinformatics approaches involving sequence and phylogenetic analysis. Homology modeling developed three-dimensional models of cacophony protein for Apis cerana and A. mellifera. Molecular docking studies were performed for various brood pheromones and volatiles, triggering hygienic behavior in honey bees, against cacophony protein providing computational insights into their molecular interactions. Binding free energy calculations using MM/PBSA and MM/GBSA consistently demonstrate a higher affinity of γ-octalactone for AcerCAC protein (−21.77 ± 3.01 kcal/mol and −24.81 ± 4.07 kcal/mol respectively) compared to AmelCAC protein (−20.03 ± 3.01 kcal/mol and −21.47 ± 3.19 kcal/mol respectively). This study lays a theoretical foundation for further studies regarding the mechanism of interaction ofcacophony with hygienic behavior.

Cacna1c deficiency in forebrain glutamatergic neurons alters behavior and hippocampal plasticity in female mice

CACNA1C, coding for the α1 subunit of L-type voltage-gated calcium channel (LTCC) Cav1.2, has been associated with multiple psychiatric disorders. Clinical studies have revealed alterations in behavior as well as in brain structure and function in CACNA1C risk allele carriers. These findings are supported by rodent models of Cav1.2 deficiency, which showed increased anxiety, cognitive and social impairments as well as a shift towards active stress-coping strategies. These behavioral alterations were accompanied by functional deficits, such as reduced long-term potentiation (LTP) and an excitation/inhibition (E/I) imbalance. However, these preclinical studies are largely limited to male rodents, with few studies exploring sex-specific effects. Here, we investigated the effects of Cav1.2 deficiency in forebrain glutamatergic neurons in female conditional knockout (CKO) mice. CKO mice exhibited hyperlocomotion in a novel environment, increased anxiety-related behavior, cognitive deficits, and increased active stress-coping behavior. These behavioral alterations were neither influenced by the stage of the estrous cycle nor by the Nex/Neurod6 haploinsufficiency or Cre expression, which are intrinsically tied to the utilization of the Nex-Cre driver line for conditional inactivation of Cacna1c. In the hippocampus, Cav1.2 inactivation enhanced presynaptic paired-pulse facilitation without altering postsynaptic LTP at CA3-CA1 synapses. In addition, CA1 pyramidal neurons of female CKO mice displayed a reduction in dendritic complexity and spine density. Taken together, our findings extend the existing knowledge suggesting Cav1.2-dependent structural and functional alterations as possible mechanisms for the behavioral alterations observed in female Cav1.2-Nex mice.

The L-type calcium channel CaV1.3: A potential target for cancer therapy.

Cancer remains a prominent cause to life expectancy, and targeted cancer therapy stands as a pivotal approach in contemporary therapy. Calcium (Ca2+) signalling plays a multifaceted role in cancer progression, such as proliferation, invasion and distant metastasis. Otherwise, it also exerts an important influence on the efficacy of clinical treatment, including cancer therapy resistance. In this review we discuss the role of the L-type calcium channel CaV1.3 (calcium voltage-gated channel subunit alpha1 D) in different types of cancers, highlighting its potential as a therapeutic target for certain cancer types. The development of selective blockers of the CaV1.3 channel has been of great interest and is expected to be a new option for the treatment of cancers such as prostate cancer and endometrial cancer. We present the pharmacological properties of CaV1.3 and the current status of selective blocker development, and analyse the challenges and possible directions for breakthroughs in the development of tailored medicines.

The role of pyroptosis-related genes in breast cancer progression

Breast cancer (BC) is one of the most common malignant cancers affecting females worldwide. Pyroptosis, a form of programmed cell death associated with inflammation and triggered by pro-inflammatory signals, is not well understood in the context of BC. This study aimed to investigate the role of pyroptosis in BC patients. Paired tumor and adjacent normal tissue samples were obtained from The Cancer Genome Atlas. Using a least absolute shrinkage and selection operator Cox analysis, we identified 15 prognostic genes associated with BC. Among these, fibrinogen C domain-containing 1, calcium voltage-gated channel subunit alpha1 H, heat shock protein family B (small) member 8, and peroxidasin-like (PXDNL) were classified as high-risk genes in BC. In contrast, the remaining 11 genes, such as proteasome activator subunit 2 and DIRAS (DIRAS family GTPase 3), were low-risk genes. Kyoto Encyclopedia of Genes and Genomes and Gene ontology analyses revealed that immune-related genes were enriched but showed reduced immunological status in the high-risk group, indicating that pro-inflammatory factors and immune antigens were produced during cell death. Consequently, targeting immune antigens with new immunosuppressants may offer a novel approach to treating BC. Moreover, the expression levels of the prognostic genes PXDNL, armadillo-like helical domain-containing 1 (ARMH1), APOBEC3D, and APOBEC3F in BC cell lines were assessed using quantitative polymerase chain reaction and western blotting. PXDNL and ARMH1 exhibited high levels of expression in BC, suggesting they could be potential therapeutic targets.

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ–3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity.

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ-3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

Identification and validation of diagnostic genes associated with neutrophil extracellular traps of type 2 diabetes mellitus.

Neutrophil extracellular traps (NETs) cause delayed wound closed up in type 2 diabetes mellitus (T2DM), but the specific regulatory mechanism of NETs-related genes (NETs-RGs) in T2DM is unclear. We acquired GSE21321 and GSE15932 datasets from gene expression omnibus (GEO) database. First, differentially expressed genes (DEGs) between T2DM and control samples of GSE21321 dataset were sifted out by differential expression analysis. NETs scores were calculated for all samples in GSE21321 dataset, and key module genes associated with NETs scores were screened by constructing co-expression network. Then, DEGs and key module genes were intersected to yield intersection genes, and candidate genes were identified by constructing a protein protein interaction (PPI) network. Least absolute shrinkage and selection operator (LASSO) regression analysis was implemented on candidate genes to screen out diagnostic genes, and they were subjected to single sample gene set enrichment analysis (ssGSEA). Finally, immune characteristic analysis was carried out, and we constructed the gene-drug and transcription factor (TF)-miRNA-mRNA networks. Besides, we validated the expression of diagnostic genes by quantitative real-time polymerase chain reaction (qRT-PCR). In total, 23 candidate genes were gained by PPI analysis. The 5 diagnostic genes, namely, inter-trypsin inhibitor heavy chain 3 (ITIH3), fibroblast growth factor 1 (FGF1), neuron cell adhesion molecule (NRCAM), advanced glycosylation end-product-specific receptor (AGER), and calcium voltage-gated channel subunit alpha1 C (CACNA1C), were identified via LASSO analysis, and they were involved in carboxylic acid transport, axonogenesis, etc. M2 Macrophage, Monocyte, Natural killer (NK) cell, and Myeloid dendritic cells (DC) were remarkably different between T2DM and control samples. Diagnostic genes had the strongest and the most significant positive correlation with B cells. The gene-drug network included CACNA1C-Isradipine, CACNA1C-Benidipine and other relationship pairs. Totally 76 nodes and 44 edges constituted the TF-miRNA-mRNA network, including signal transducer and activator of transcription 1(STAT1) -hsa-miR-3170-AGER, CCCTC-binding factor (CTCF)-hsa-miR-455-5p-CACNA1C, etc. Moreover, qRT-PCR suggested that the expression trends of FGF1 and AGER were in keeping with the results of bioinformatic analysis. FGF1 and AGER were markedly regulated downwards in the T2DM group. Through bioinformatic analysis, we identified NETs-related diagnostic genes (ITIH3, FGF1, NRCAM, AGER, CACNA1C) in T2DM, and explored their mechanism of action from different aspects, providing new ideas for the studies related to diagnosis and treatment of T2DM.

Mirogabalin: a novel gabapentinoid or another false dawn?

Mirogabalin is a novel gabapentinoid medication for the treatment of neuropathic pain. The purpose of this review is to discuss current evidence for its use. Gabapentinoids are widely prescribed for neuropathic pain. Mirogabalin offers theoretical advantages over traditional gabapentinoids due to its specificity for the α2δ-1 subunit of voltage-gated calcium channels. It is theorised that this specificity may reduce adverse drug reactions by minimising binding to the α2δ-2 subunit which is responsible for many of the gabapentinoid side effects. Mirogabalin's slower dissociation from the α2δ-1 compared with α2δ-2, and its higher potency may also impart an efficacy benefit over traditional gabapentinoids. These theoretical advantages of mirogabalin remain inconclusive in clinical practice, with mixed evidence regarding mirogabalin versus traditional gabapentinoids. Some studies suggest a reduced side effect profile yet, others fail to demonstrate significant differences. Regarding efficacy, mirogabalin may be superior to placebo for several neuropathic pain syndromes, but evidence of widespread benefit over traditional gabapentinoids is currently lacking. Mirogabalin offers theoretical promise, but large, independent studies are required to further assess its performance versus traditional gabapentinoids.

A biallelic mutation in CACNA2D2 associated with developmental and epileptic encephalopathy affects calcium channel-dependent as well as synaptic functions of α2δ-2.

α2δ proteins serve as auxiliary subunits of voltage-gated calcium channels and regulate channel membrane expression and current properties. Besides their channel function, α2δ proteins regulate synapse formation, differentiation, and synaptic wiring. Considering these important functions, it is not surprising that CACNA2D1-4, the genes encoding for α2δ-1 to -4 isoforms, have been implicated in neurological, neurodevelopmental, and neuropsychiatric disorders. Mutations in CACNA2D2 have been associated with developmental and epileptic encephalopathy (DEE) and cerebellar atrophy. In our present study, we performed a detailed functional characterization of the p.R593P mutation in α2δ-2, a homozygous mutation previously identified in two siblings with DEE. Importantly, we analyzed both calcium channel-dependent as well as synaptic functions of α2δ-2. Our data show that the corresponding p.R596P mutation in mouse α2δ-2 drastically decreases membrane expression and synaptic targeting of α2δ-2. This defect correlates with altered biophysical properties of postsynaptic CaV1.3 channel but has no effect on presynaptic CaV2.1 channels upon heterologous expression in tsA201 cells. However, homologous expression of α2δ-2_R596P in primary cultures of hippocampal neurons affects the ability of α2δ-2 to induce a statistically significant increase in the presynaptic abundance of endogenous CaV2.1 channels and presynaptic calcium transients. Moreover, our data demonstrate that in addition to lowering membrane expression, the p.R596P mutation reduces the trans-synaptic recruitment of GABAA receptors and presynaptic synapsin clustering in glutamatergic synapses. Lastly, the α2δ-2_R596P reduces the amplitudes of glutamatergic miniature postsynaptic currents in transduced hippocampal neurons. Taken together, our data strongly link the human biallelic p.R593P mutation to the underlying severe neurodevelopmental disorder and highlight the importance of studying α2δ mutations not only in the context of channelopathies but also synaptopathies.

Genetic variants and down-regulation of CACNA1H in pheochromocytoma.

Pheochromocytoma (PCC) and abdominal paraganglioma (aPGL) (together abbreviated PPGL) frequently present with an underlying genetic event in a PPGL driver gene, and additional susceptibility genes are anticipated. Here, we re-analyzed whole-exome sequencing data for PCC patients and identified two patients with rare missense variants in the calcium voltage-gated channel subunit 1H gene (CACNA1H). CACNA1H variants were also found in the clinical setting in PCC patients using targeted sequencing and from analysis of The Cancer Genome Atlas database. In total, CACNA1H variants were found in six PCC cases. Three of these were constitutional, and two are known to have functional consequences on hormone production and gene expression in primary aldosteronism and aldosterone-producing adrenocortical adenoma. In general, PPGL exhibited reduced CACNA1H mRNA expression as compared to normal adrenal. Immunohistochemistry showed strong CACNA1H (CaV3.2) staining in adrenal medulla while PPGL typically had weak or negative staining. Reduced CACNA1H gene expression was especially pronounced in PCC compared to aPGL and in PPGL with cluster 2 kinase signaling phenotype. Furthermore, CACNA1H levels correlated with HIF1A and HIF2A. Moreover, TCGA data revealed a correlation between CACNA1H methylation density and gene expression. Expression of rCacna1h in PC12 cells induced differential protein expression profiles, determined by mass spectrometry, as well as a shift in the membrane potential where maximum calcium currents were observed, as determined by electrophysiology. The findings suggest the involvement of CACNA1H/CaV3.2 in pheochromocytoma development and establish a potential link between the etiology of adrenomedullary and adrenocortical tumor development.

Ca2+ channel and active zone protein abundance intersects with input-specific synapse organization to shape functional synaptic diversity.

Synaptic heterogeneity is a hallmark of nervous systems that enables complex and adaptable communication in neural circuits. To understand circuit function, it is thus critical to determine the factors that contribute to the functional diversity of synapses. We investigated the contributions of voltage-gated calcium channel (VGCC) abundance, spatial organization, and subunit composition to synapse diversity among and between synapses formed by two closely related Drosophila glutamatergic motor neurons with distinct neurotransmitter release probabilities (Pr). Surprisingly, VGCC levels are highly predictive of heterogeneous Pr among individual synapses of either low- or high-Pr inputs, but not between inputs. We find that the same number of VGCCs are more densely organized at high-Pr synapses, consistent with tighter VGCC-synaptic vesicle coupling. We generated endogenously tagged lines to investigate VGCC subunits in vivo and found that the α2δ-3 subunit Straightjacket along with the CAST/ELKS active zone (AZ) protein Bruchpilot, both key regulators of VGCCs, are less abundant at high-Pr inputs, yet positively correlate with Pr among synapses formed by either input. Consistently, both Straightjacket and Bruchpilot levels are dynamically increased across AZs of both inputs when neurotransmitter release is potentiated to maintain stable communication following glutamate receptor inhibition. Together, these findings suggest a model in which VGCC and AZ protein abundance intersects with input-specific spatial and molecular organization to shape the functional diversity of synapses.

HYPERTROPHIC CARDIOMYOPATHY AND MYBPC3 VARIANT - A CLINICAL CASE

Abstract Introduction Hypertrophic cardiomyopathy is a primary pathology of the cardiac muscle. Sarcomeric forms of hypertrophic cardiomyopathy (HCM) often have autosomal dominant transmission. A pathogenetic or likely pathogenetic mutation affecting genes encoding sarcomeric proteins is present in 30-60% of cases. In this study, we present a case of a family affected by hypertrophic cardiomyopathy with a mutation classified as of uncertain significance in the MYBPC3 gene. Clinical Case Mr. AA, 74 years old, attended the cardiomyopathy outpatient clinic of our hospital in June 2021 due to worsening heart failure with an hypertrophic phenotype. His medical history reported an increase in the thickness of the interventricular septum (IVS) since 1985. In 2015, the patient underwent pacemaker implantation for symptomatic 2:1 atrioventricular block associated with syncope and complete left bundle branch block. Since 2016, he had paroxysmal atrial fibrillation complicated by an ischemic stroke in 2019 with subtherapeutic INR. Cardiac magnetic resonance imaging (MRI) or genetic evaluation had never been performed. During the visit, the patient reported that his sister (AG, 73 years old) had undergone tests due to diffuse negative T waves findings in a previous ECG, revealing the presence of a long myocardial bridge of the left anterior descending artery (LAD). No family history of sudden cardiac death was reported. The echocardiogram of AA showed LV hypertrophy (septal wall thickness/posterior wall thickness 18/15 mm, respectively) with an ejection fraction of 36%. Suspecting sarcomeric HCM, a genetic test (TruSight One Expanded Illumina) was performed, revealing two variants of uncertain significance in heterozygosity in the CACNA1C - Calcium Voltage-Gated Channel Subunit Alpha1 C gene (c.2460G>C p.(Lys820Asn)) and MYBPC3 gene (c.2030C>T p.(Pro677Leu)). After a few months, AG presented MRI results suggestive of HCM apical variant (Figure 1). The genetic consultant recommended family screening, and the pedigree is shown in Figure 2. All carriers of the CACNA1C mutation had a negative phenotype. AG's son, IF, 56 years old, carriers of MYBPC3 mutation, presented an MRI compatible with early-stage HCM (Figure 3). His son, carriers of MYBPC3 mutation as well, is now awaiting a cardiac MRI. Conclusions In the family presented here, the MYBPC3 variant (c.2030C>T p.(Pro677Leu)) appears to be correlated with the development of sarcomeric hypertrophic cardiomyopathy. Registry studies with a large sample size are desirable to accurately classify variants of uncertain significance, which are becoming more common due to the widespread use of genetic tests.

Molecular Mechanisms and Therapeutic Potential of Gabapentin with a Focus on Topical Formulations to Treat Ocular Surface Diseases.

Gabapentin (GBP) was originally developed as a potential agonist for Gamma-Amino-Butyric-Acid (GABA) receptors, aiming to inhibit the activation of pain-signaling neurons. Contrary to initial expectations, it does not bind to GABA receptors. Instead, it exhibits several distinct pharmacological activities, including: (1) binding to the alpha-2-delta protein subunit of voltage-gated calcium channels in the central nervous system, thereby blocking the excitatory influx of calcium; (2) reducing the expression and phosphorylation of CaMKII via modulation of ERK1/2 phosphorylation; (3) inhibiting glutamate release and interfering with the activation of NMDA receptors; (4) enhancing GABA synthesis; (5) increasing cell-surface expression of δGABA_A receptors, contributing to its antinociceptive, anticonvulsant, and anxiolytic-like effects. Additionally, GBP displays (6) inhibition of NF-kB activation and subsequent production of inflammatory cytokines, and (7) stimulation of the purinergic adenosine A1 receptor, which supports its anti-inflammatory and wound-healing properties. Initially approved for treating seizures and postherpetic neuralgia, GBP is now broadly used for various conditions, including psychiatric disorders, acute and chronic neuropathic pain, and sleep disturbances. Recently, as an eye drop formulation, it has also been explored as a therapeutic option for ocular surface discomfort in conditions such as dry eye, neurotrophic keratitis, corneal ulcers, and neuropathic ocular pain. This review aims to summarize the evidence supporting the molecular effects of GBP, with a special emphasis on its applications in ocular surface diseases.

NRN1 epistasis with BDNF and CACNA1C: mediation effects on symptom severity through neuroanatomical changes in schizophrenia

The expression of Neuritin-1 (NRN1), a neurotrophic factor crucial for neurodevelopment and synaptic plasticity, is enhanced by the Brain Derived Neurotrophic Factor (BDNF). Although the receptor of NRN1 remains unclear, it is suggested that NRN1’s activation of the insulin receptor (IR) pathway promotes the transcription of the calcium voltage-gated channel subunit alpha1 C (CACNA1C). These three genes have been independently associated with schizophrenia (SZ) risk, symptomatology, and brain differences. However, research on how they synergistically modulate these phenotypes is scarce. We aimed to study whether the genetic epistasis between these genes affects the risk and clinical presentation of the disorder via its effect on brain structure. First, we tested the epistatic effect of NRN1 and BDNF or CACNA1C on (i) the risk for SZ, (ii) clinical symptoms severity and functionality (onset, PANSS, CGI and GAF), and (iii) brain cortical structure (thickness, surface area and volume measures estimated using FreeSurfer) in a sample of 86 SZ patients and 89 healthy subjects. Second, we explored whether those brain clusters influenced by epistatic effects mediate the clinical profiles. Although we did not find a direct epistatic impact on the risk, our data unveiled significant effects on the disorder’s clinical presentation. Specifically, the NRN1-rs10484320 x BDNF-rs6265 interplay influenced PANSS general psychopathology, and the NRN1-rs4960155 x CACNA1C-rs1006737 interaction affected GAF scores. Moreover, several interactions between NRN1 SNPs and BDNF-rs6265 significantly influenced the surface area and cortical volume of the frontal, parietal, and temporal brain regions within patients. The NRN1-rs10484320 x BDNF-rs6265 epistasis in the left lateral orbitofrontal cortex fully mediated the effect on PANSS general psychopathology. Our study not only adds clinical significance to the well-described molecular relationship between NRN1 and BDNF but also underscores the utility of deconstructing SZ into biologically validated brain-imaging markers to explore their mediation role in the path from genetics to complex clinical manifestation.

Altered Hippocampal Activation in Seizure-Prone CACNA2D2 Knock-out Mice.

The voltage-gated calcium channel subunit α2δ-2 controls calcium-dependent signaling in neurons, and loss of this subunit causes epilepsy in both mice and humans. To determine whether mice without α2δ-2 demonstrate hippocampal activation or histopathological changes associated with seizure activity, we measured expression of the activity-dependent gene c-fos and various histopathological correlates of temporal lobe epilepsy (TLE) in hippocampal tissue from wild-type (WT) and α2δ-2 knock-out (CACNA2D2 KO) mice using immunohistochemical staining and confocal microscopy. Both genotypes demonstrated similarly sparse c-fos and ΔFosB expressions within the hippocampal dentate granule cell layer (GCL) at baseline, consistent with no difference in basal activity of granule cells between genotypes. Surprisingly, when mice were assayed 1 h after handling-associated convulsions, KO mice had fewer c-fos-positive cells but dramatically increased ΔFosB expression in the dentate gyrus compared with WT mice. After administration of a subthreshold pentylenetetrazol dose, however, KO mice dentate had significantly more c-fos expression compared with WT mice. Other histopathological markers of TLE in these mice, including markers of neurogenesis, glial activation, and mossy fiber sprouting, were similar between WT and KO mice, apart from a small but statistically significant increase in hilar mossy cell density, opposite to what is typically found in mice with TLE. This suggests that the differences in seizure-associated dentate gyrus function in the absence of α2δ-2 protein are likely due to altered functional properties of the network without associated structural changes in the hippocampus at the typical age of seizure onset.

α2δ1-mediated maladaptive sensory plasticity disrupts adipose tissue homeostasis following spinal cord injury

Spinal cord injury (SCI) increases the risk of cardiometabolic disorders, including hypertension, dyslipidemia, and insulin resistance. Not only does SCI lead to pathological expansion of adipose tissue, but it also leads to ectopic lipid accumulation in organs integral to glucose and insulin metabolism. The pathophysiological changes that underlie adipose tissue dysfunction after SCI are unknown. Here, we find that SCI exacerbates lipolysis in epididymal white adipose tissue (eWAT). Whereas expression of the α2δ1 subunit of voltage-gated calcium channels increases in calcitonin gene-related peptide-positive dorsal root ganglia neurons that project to eWAT, conditional deletion of the gene encoding α2δ1 in these neurons normalizes eWAT lipolysis after SCI. Furthermore, α2δ1 pharmacological blockade through systemic administration of gabapentin also normalizes eWAT lipolysis after SCI, preventing ectopic lipid accumulation in the liver. Thus, our study provides insight into molecular causes of maladaptive sensory processing in eWAT, facilitating the development of strategies to reduce metabolic and cardiovascular complications after SCI.

Quercetin alleviates chronic unpredictable mild stress-induced depression-like behavior by inhibiting NMDAR1 with α2δ-1 in rats.

Depression is a serious mental disorder and the most prevalent cause of disability and suicide worldwide. Chronic unpredictable mild stress (CUMS) can lead to a significant acceleration of depression development. Quercetin (Que) is a flavonoid compound with a wide range of pharmacological effects. Recent studies have shown that quercetin can improve CUMS-induced depression-like behavior, but the mechanism of its improvement is still unclear. α2δ-1 is a regulatory subunit of voltage-gated calcium channel, which can interact with N-methyl-D-aspartate receptor (NMDAR) to form a complex. In this study, we found that Que could inhibit the increase of α2δ-1 and NMDAR expression in rat hypothalamus induced by CUMS. In pain, chronic hypertension and other studies have shown that α2δ-1 interacts with the NMDAR to form a complex, which subsequently affects the expression level of NMDAR. Consequently, the present study aimed to investigate the antidepressant effect of Que invivo and invitro and to explore its mechanism of action in terms of the interaction between α2δ-1 and NMDAR. Rats were randomly exposed to two stressors every day for 4 weeks to establish a CUMS rat model, then sucrose preference test (SPT), forced swimming test (FST), tail suspension test (TST), and open field test (OFT) were performed to detect the behavior of CUMS rats, so as to evaluate whether the CUMS rat model was successfully established and the improvement effect of Que on CUMS-induced depression-like behavior in rats. Experimental techniques such as serum enzyme-linked immunosorbent assay (ELISA), immunofluorescence, Western blot, and co-immunoprecipitation, as well as invitro experiments, were used to investigate the mechanisms by which Que exerts its antidepressant effects. Behavioral and ELISA test results showed that Que could produce a reduction in the excitability of the hypothalamic-pituitary-adrenal (HPA) axis in CUMS rats and lead to significant improvements in their depressive behavior. Western blot, immunofluorescence, and co-immunoprecipitation experiments showed that Que produced a decrease in NMDAR1 and α2δ-1 expression levels and interfered with α2δ-1 and NMDAR1 binding. In addition, the neural regulation mechanism of Que on antidepressant effect in PC12 cells knocked out α2δ-1 gene was further verified. Cellular experiments demonstrated that Que led to a reversal of up-regulation of NMDAR1 and α2δ-1 expression levels in corticosterone-injured PC12 cells, while Que had no effects on NMDAR1 expression in PC12 cells with the α2δ-1 gene knockout. Que has a good antidepressant effect and can significantly improve the depression-like behavior caused by CUMS. It exerts antidepressant effects by inhibiting the expression level of α2δ-1, interfering with the interaction between α2δ-1 and NMDAR, and then reducing the excitability of the HPA axis.