Voltage-gated Channels Research Articles

Association of the dopamine D2 receptor gene SNP rs1800497 with postoperative nausea and vomiting

BACKGROUND Postoperative nausea and vomiting (PONV) are the most frequent complications in the context of anaesthesia. Several studies suggest a contribution of genetic traits to PONV disposition. Single nucleotide polymorphisms (SNPs) located in the cholinergic receptor muscarinic 3 gene CHRM3 (rs2165870) and the potassium voltage-gated channel subfamily B member 2 KCNB2 (rs349358) have been described as independent risk factors for the occurrence of PONV. In addition, further SNPs might be associated with an increased PONV risk, for example a dopamine D2 receptor (DRD2) SNP (rs1800497). OBJECTIVE The primary aim of our study was the development of a new PONV prediction score which includes genetic information of SNPs in the genes CHRM3 and KCNB2, which have been already associated with PONV. The secondary aim of our study was to investigate the association of five additional SNPs with PONV. DESIGN Prospective cohort study. SETTING Single centre study in Germany. RESULTS We could not establish a new PONV prediction score that includes genetic information, due to limited association of the KCNB2 SNP and CHRM3 SNP with PONV. Interestingly, the GA and AA genotypes of the DRD2 rs1800497 in the dopamine D2 receptor gene were associated with PONV 24 h postoperatively, with a relative risk (RR) of GA/AA genotype vs. GG genotype of 1.5 [95% confidence interval (CI) 1.06 to 2.01, P = 0.02]. This association was independent from the Apfel score in a multivariate logistic regression analysis (RR 1.4, 95% CI 1.03 to 1.90, P = 0.03). CONCLUSION The construction of a new PONV prediction score including genetic information was not possible due to limited association of the CHRM3 and KCNB2 SNPs. However, the DRD2 GA and AA genotypes (rs1800497) were associated with PONV and this SNP might be a future candidate for further validation studies aiming for molecular-derived PONV prediction models. TRIAL REGISTRATION German Clinical Study Register – DRKS00021051.

Effect of Crude Extract from the Sea Anemone Bunodeopsis globulifera on Voltage-Gated Ion Channels from Central and Peripheral Murine Nervous Systems.

Sea anemones are an important source of bioactive compounds with potential pharmacological applications. Their toxins are produced and stored in organelles called nematocysts and act on specific targets, including voltage-gated ion channels. To date, sea anemone toxins have demonstrated effects on voltage-gated sodium and potassium channels, facilitating investigations into the structure and function of these proteins. In this study, we evaluated the effect of Bunodeopsis globulifera sea anemone crude extract, and of a low molecular weight fraction, on voltage-gated sodium and calcium channels within the murine nervous system. Notably, the crude extract led to a significant reduction in total sodium current, while also triggering calcium-dependent glutamate release. Furthermore, the low molecular weight fraction, in particular, enhanced total calcium currents and current density. These findings underscore the existence of sea anemone toxins with diverse mechanisms of action beyond those previously documented.

Coupling sensor to enzyme in the voltage sensing phosphatase

Voltage-sensing phosphatases (VSPs) dephosphorylate phosphoinositide (PIP) signaling lipids in response to membrane depolarization. VSPs possess an S4-containing voltage sensor domain (VSD), resembling that of voltage-gated cation channels, and a lipid phosphatase domain (PD). The mechanism by which voltage turns on enzyme activity is unclear. Structural analysis and modeling suggest several sites of VSD-PD interaction that could couple voltage sensing to catalysis. Voltage clamp fluorometry reveals voltage-driven rearrangements in three sites implicated earlier in enzyme activation—the VSD-PD linker, gating loop and R loop—as well as the N-terminal domain, which has not yet been explored. N-terminus mutations perturb both rearrangements in the other segments and enzyme activity. Our results provide a model for a dynamic assembly by which S4 controls the catalytic site.

In Silico Toxicological Analysis of Active Compounds Present in Selected Pesticides Sold in South-West Nigeria

Introduction: The study investigated the molecular effects of human exposure to commonly used pesticides in Nigeria. Methods: Utilizing computational methods like clustering analysis, toxicokinetic predictions, molecular docking, and molecular dynamic (MD) simulation, various health impacts were identified. Results and Discussion: The results revealed significant gastrointestinal absorption, P-glycoprotein bypass, blood-brain barrier penetration, and cytochrome P450 inhibition for certain pesticide agents. Notably, oxathiapiprolin showed hepatotoxicity, propanil exhibited drug-induced liver injury (DILI), and 2,4-dichloro-phenoxyacetic acid demonstrated carcinogenicity. Respiratory toxicity was predicted for most pesticides, except propanil and N-(2,6-diethylphenyl) acetamide. Molecular targets were identified, such as bifenthrin targeting programmed cell death 1 ligand 1 and Atrazine targeting potassium voltage-gated channel subfamily H member 3. Binding affinities were computed, with oxathiapiprolin showing -6.526 kcal/mol with short transient receptor potential channel 7. Molecular dynamic simulations indicated significant binding energy changes over time. Atrazine's binding with potassium voltage-gated channel subfamily H member 3 exhibited a total binding energy ΔGbind of -39.410 kcal/mol and -49.135 kcal/mol at 0 ns and 100 ns, respectively. Oxathiapiprolin's binding with short transient receptor potential channel 7 showed ΔGbind of -53.481 kcal/mol and -44.122 kcal/mol at 0 ns and 100 ns. Conclusion: This study suggests potential hepatotoxicity and carcinogenicity of certain pesticides, emphasizing the need for environmental monitoring and stringent regulations to safeguard public health.

Preliminary study on the role and mechanism of IL-6 receptor antagonists in improving post-infarction ventricular arrhythmia

Objective: To investigate the effect of tocilizumab (TCZ) on ventricular arrhythmias (VAs) after myocardial infarction (MI) in Sprague-Dawley rats and explore its potential mechanism. Methods: The random number table method was used to divide 32 adult male Sprague-Dawley rats into 4 groups: Sham group, TCZ group, MI group and MI+TCZ group, with 8 rats in each group. The MI model was established by ligation of the left anterior descending branch of the coronary artery in the MI and MI+TCZ groups, and only sutured without ligation in the Sham and TCZ groups. TCZ was injected into the left superior cervical ganglion (SCG) of rats in the TCZ and MI+TCZ groups after successful modeling or sham operation, and the same amount of normal saline was injected in the Sham and MI groups. 24 h after successful modeling, ECG of rats in each group was recorded, heart rate variability (HRV, including low frequency power (LF), high frequency power (HF), LF/HF ratio), QT interval, QTc interval were calculated, and left ventricular effective refractory period (ERP) and VA inducibility were measured. Myocardial infarct size and tissue changes were observed with triphenyl tetrazolium chloride staining and HE staining. Real-time PCR analysis was used to detect the messager RNA (mRNA) expression of interleukin-6 (IL-6) and signal transducer and activator of transcription (STAT) 3 in SCG and potassium voltage-gated channel subfamily D member 2 (Kcnd2) in myocardial infarction periphery. The expression of c-fos in SCG was detected by immunofluorescence staining. Results: Compared with Sham group and MI+TCZ group, rats in MI group had higher LF and LF/HF ratio, longer QT interval and QTc interval, more VAs induced, lower HF and shorter ERP (P all<0.05). Triphenyl tetrazolium chloride staining and HE staining showed that rats in the Sham and TCZ groups had normal myocardial tissue structure, those in the MI group had severe myocardial injury, and those in the MI+TCZ group had less myocardial injury than those in the MI group. Real-ime PCR analysis showed that compared with Sham group and MI+TCZ group, mRNA expression levels of IL-6 and STAT3 in SCG of rats in MI group were higher, and mRNA expression level of myocardial Kcnd2 was lower (P all<0.05). Immunofluorescence staining showed that the content of c-fos in SCG of rats in MI group was higher than that of Sham group and MI+TCZ group (P all<0.05). Conclusions: TCZ may reduce neural activity of the SCG after MI by inhibiting the IL-6/STAT3 signaling pathway, thereby alleviating myocardial injury and inhibiting VAs.

The Therapeutic Role of Perampanel in Treating Pediatric Patients With Dravet Syndrome: A Scoping Review.

Sodium channelopathies are genetic disorders caused by mutations in genes, including sodium voltage-gated channel alpha subunit 1 (SCN1A),that lead to several epilepsy syndromes. Traditional treatments with sodium channel blockers often have limited effectiveness and side effects. Dravet syndrome (DS), a severe epilepsy starting in infancy, presents significant treatment challenges. Perampanel (PER), a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, has shown promise for DS, reducing seizure frequency and improving quality of life (QoL). The limited availability of randomized controlled trials on PER among DS is challenging, but broader studies on refractory epilepsies offer insights. Real-world studies support PER's efficacy, underscoring its potential for managing refractory seizures in DS. Studies showed long-term effectiveness in reducing seizure frequency and enhancing QoL. While PER has minimal impact on cognitive development, it significantly improves seizure control. Numerous studies confirm the use of PER as an effective adjunctive treatment for DS; however, it is crucial to observe the safety profile, especially for pediatric sodium channelopathy patients. Common side effects include dizziness, drowsiness, and irritability, necessitating careful management. Long-term safety is generally favorable, but monitoring for behavioral and mood changes is essential. Additionally, the response to PER in DS varies widely, complicating its use. The limited clinical data and the need for careful dosage monitoring, especially in children, present significant challenges. Side effects, potential drug interactions, and high costs further complicate treatment. Despite increasing attention to its cost-effectiveness, accessibility remains limited in some regions, posing significant barriers for many families. In this paper, we review the role of PER in treating pediatric patients with DS, emphasizing clinical evidence and practical considerations.

Voltage-Gated Ion Channels: Structure, Pharmacology and Photopharmacology.

Voltage-gated ion channels are transmembrane proteins responsible for the generation and propagation of action potentials in excitable cells. Over the last decade, advancements have enabled the elucidation of crystal structures of ion channels. This progress in structural understanding, particularly in identifying the binding sites of local anesthetics, opens avenues for the design of novel compounds capable of modulating ion conduction. However, many traditional drugs lack selectivity and come with adverse side effects. The emergence of photopharmacology has provided an orthogonal way of controlling the activity of compounds, enabling the regulation of ion conduction with light. In this review, we explore the central pore region of voltage-gated sodium and potassium channels, providing insights from both structural and pharmacological perspectives. We discuss the different binding modes of synthetic compounds that can physically occlude the pore and, therefore, block ion conduction. Moreover, we examine recent advances in the photopharmacology of voltage-gated ion channels, introducing molecular approaches aimed at controlling their activity by using photosensitive drugs.

The involvement of krüppel-like transcription factor 2 in megakaryocytic differentiation induction by phorbol 12-myrestrat 13-acetate

BackgroundMegakaryocytic differentiation is a complicated process regulated by a series of transcription factors in a context- and stage-dependent manner. Recent studies have suggested that krüppel-like transcription factor 2 (KLF2) is involved in the control of embryonic erythroid precursor cell differentiation and maturation. However, the function and mechanism of KLF2 in regulating megakaryocytic differentiation remain unclear.MethodsThe expression patterns of krüppel-like transcription factors (KLFs) during megakaryocytic differentiation were identified from public databases. Phorbol 12-myristate 13-acetate (PMA) treatment of the myeloid-erythroid-leukemic cell lines K562 and HEL were used as cellular megakaryocytic differentiation models. A lentiviral transduction system was utilized to achieve the goal of amplifying or reducing KLF2. The expression of KLF2 was examined using real-time PCR and western blot. The impact of KLF2 on the megakaryocytic differentiation of K562 cells was examined by flow cytometry, Giemsa staining, Phalloidin staining and western blot. RNA-sequencing (RNA-seq) and chromatin immunoprecipitation-sequencing (ChIP-seq) technologies were used to identify the KLF2-regulated targets.ResultsKLF2 is increased in the maturation process of megakaryocytes. KLF2 overexpression accelerated the PMA-induced megakaryocytic differentiation, as reflected by an increased percentage of CD41/CD61 cells, an increased number of polyploid cells, and an elevated expression of P21 and P27. KLF2 knockdown exhibited the opposite results, indicating that KLF2 knockdown suppressed the megakaryocytic differentiation. Further, combination of the RNA-seq and ChIP-seq results suggested that chimerin 1 (CHN1) and potassium voltage-gated channel subfamily Q member 5 (KCNQ5) may be target genes regulated of KLF2. Both CHN1 and KCNQ5 knockdown could block the megakaryocytic differentiation to some content.ConclusionThis study implicated a regulatory role of KLF2 in megakaryocytic differentiation, which may suggest KLF2 as a target for illness with abnormal megakaryocytic differentiation.

An essential role for the Hv1 voltage-gated proton channel in Pseudomonas aeruginosa corneal infection.

Assembly of NADPH oxidase 2 (NOX2) proteins in neutrophils plays an essential role in controlling microbial infections by producing high levels of reactive oxygen species (ROS). In contrast, the role of the Hv1 voltage-gated proton channel that is required for sustained NOX2 activity is less well characterized. We examined the role of Hv1 in a murine model of blinding Pseudomonas aeruginosa corneal infection and found that in contrast to C57BL/6 mice, Hvcn1 -/- mice exhibit an impaired ability to kill bacteria and regulate disease severity. In vitro, we used a novel Hv1 Inhibitor Flexible (HIF) to block ROS production by human and murine neutrophils and found that HIF inhibits ROS production in a dose-dependent manner following stimulation with PMA or infection with P. aeruginosa. Collectively, these findings demonstrate an important role for Hv1 on controlling bacterial growth in a clinically relevant bacterial infection model.

Voltage-Gated Ion Channels Are Transcriptional Targets of Sox10 during Oligodendrocyte Development.

The transcription factor Sox10 is an important determinant of oligodendroglial identity and influences oligodendroglial development and characteristics at various stages. Starting from RNA-seq data, we here show that the expression of several voltage-gated ion channels with known expression and important function in oligodendroglial cells depends upon Sox10. These include the Nav1.1, Cav2.2, Kv1.1, and Kir4.1 channels. For each of the four encoding genes, we found at least one regulatory region that is activated by Sox10 in vitro and at the same time bound by Sox10 in vivo. Cell-specific deletion of Sox10 in oligodendroglial cells furthermore led to a strong downregulation of all four ion channels in a mouse model and thus in vivo. Our study provides a clear functional link between voltage-gated ion channels and the transcriptional regulatory network in oligodendroglial cells. Furthermore, our study argues that Sox10 exerts at least some of its functions in oligodendrocyte progenitor cells, in myelinating oligodendrocytes, or throughout lineage development via these ion channels. By doing so, we present one way in which oligodendroglial development and properties can be linked to neuronal activity to ensure crosstalk between cell types during the development and function of the central nervous system.

Low Expression of SCN4B Predicts Poor Prognosis in Non-Small Cell Lung Cancer.

Sodium voltage-gated channel beta subunit 4 (SCN4B) plays a suppressive role in various tumors. However, the role of SCN4B in non-small cell lung cancer (NSCLC) is not yet clear. This study aims to investigate the expression of SCN4B in NSCLC patients and its correlation with prognosis. Firstly, the expression of SCN4B in non-small cell lung cancer (NSCLC) was analyzed using The Cancer Genome Atlas (TCGA) database. Then, differential expression genes (DEGs) were identified using R software. Next, DEG enrichment pathways were analyzed using the R package clusterProfiler. Protein-protein interaction networks were revealed through STRING analysis. A heatmap showed significant differential expression of SCN4B. Further analysis included examining SCN4B expression in a pan-cancer context and its correlation with 24 types of immune cells in NSCLC. Subsequently, quantitative real-time polymerase chain reaction (qRT-PCR), Western Blot, immunohistochemistry, and clinical data were used to validate SCN4B expression and prognostic value in NSCLC patients. SCN4B mRNA expression in non-small cell lung cancer tissues was significantly lower than in adjacent normal tissues (p < 0.001). Clinical correlation analysis confirmed its association with clinical pathology. Gene set enrichment analysis (GSEA) and tumor immune-related analyses indicated that SCN4B is involved in NSCLC-related Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and participates in immune infiltration. qRT-PCR, Western Blot, and immunohistochemistry also confirmed that SCN4B is downregulated in NSCLC patients and is associated with poor prognosis. SCN4B is downregulated in tumor tissues of NSCLC patients and is associated with a poor prognosis.

Dimerization is required for the glycosylation of S1-S2 linker of sea urchin voltage-gated proton channel Hv1

Multimerization of ion channels is essential for establishing the ion-selective pathway and tuning the gating regulated by membrane potential, second messengers, and temperature. Voltage-gated proton channel, Hv1, consists of voltage-sensor domain and coiled-coil domain. Hv1 forms dimer, whereas voltage-dependent channel activity is self-contained in monomer unlike many ion channels, which assemble to form ion-conductive pathways among multiple subunits. Dimerization of Hv1 is necessary for cooperative gating, but other roles of dimerization in physiological aspects are still largely unclear. In this study, we show that dimerization of Hv1 takes place in ER. Sea urchin Hv1 (Strongylocentrotus purpuratus Hv1: SpHv1) was glycosylated in the consensus sequence for N-linked glycosylation within the S1-S2 extracellular loop. However, glycosylation was not observed in the monomeric SpHv1 that lacks the coiled-coil domain. A version of mHv1 in which the S1-S2 loop was replaced by that of SpHv1 showed glycosylation and its monomeric form was not glycosylated. Tandem dimer of monomeric SpHv1 underwent glycosylation, suggesting that dimerization of Hv1 is required for glycosylation. Moreover, when monomeric Hv1 has a dilysine motif in the C-terminal end, which is known to act as a retrieval signal from Golgi to ER, prolonging the time of residency in ER, it was glycosylated. Overall, our results suggest that monomeric SpHv1 does not stay long in ER, thereby escaping glycosylation, while the dimerization causes the proteins to stay longer in ER. Thus, the findings highlight the novel significance of dimerization of Hv1: regulation of biogenesis and maturation of the proteins in intracellular compartments.

Interior pH-sensing residue of human voltage-gated proton channel Hv1 is histidine 168

The molecular mechanisms governing the human voltage-gated proton channel hHv1 remain elusive. Here, we used membrane-enabled hybrid-solvent continuous constant pH molecular dynamics (CpHMD) simulations with pH replica exchange to further evaluate the structural models of hHv1 in the closed (hyperpolarized) and open (depolarized) states recently obtained with MD simulations and explore potential pH-sensing residues. The CpHMD titration at a set of symmetric pH conditions revealed three residues that can gain or lose protons upon channel depolarization. Among them, residue H168 at the intracellular end of the S3 helix switches from the deprotonated to the protonated state and its protonation is correlated with the increased tilting of the S3 helix during the transition from the closed to the open state. Thus, the simulation data suggest H168 as an interior pH sensor, in support of a recent finding based on electrophysiological experiments of Hv1 mutants. We propose that protonation of H168 acts as a key that unlocks the closed channel configuration by increasing the flexibility of the S2-S3 linker, which increases the tilt angle of S3 and enhances the mobility of the S4 helix, thus promoting channel opening. Our work represents an important step toward deciphering the pH-dependent gating mechanism of hHv1.

A novel variant c.902C>A (p. A301D) in KCNQ4 associated with non-syndromic deafness 2A in a Chinese family.

Deafness autosomal dominant 2A (DFNA2A) is related to non-syndromic genetic hearing impairment. The KCNQ4 (Potassium Voltage-Gated Channel Subfamily Q Member 4) can lead to DFNA2A. In this study, we report a case of autosomal dominant non-syndromic hearing loss with six family members as caused by a novel variant in the KCNQ4 gene. The whole-exome sequencing (WES) and pure tone audiometry were performed on the proband of the family. Sanger sequencing was conducted on family members to determine if the novel variant in the KCNQ4 gene was present. Evolutionary conservation analysis and computational tertiary structure protein prediction of the wild-type KCNQ4 protein and its variant were then performed. In addition, voltage-gated channel activity of the wild-type KCNQ4 protein and its variant were tested using whole-cell patch clamp. It was observed that the proband had inherited autosomal dominant, non-syndromic sensorineural hearing loss as a trait. A novel co-segregating heterozygous missense variant (c.902C>A, p.Ala301Asp) of the KCNQ4 gene was identified in the proband and other five affected family members. This variant was predicted to cause an alanine-to-aspartic acid substitution at position 301 in the KCNQ4 protein. The alanine at position 301 is well conserved across different species. Whole-cell patch clamp showed that there was a significant difference between the WT protein currents and the mutant protein currents in the voltage-gated channel activity. In the present study, performing WES in conjunction with Sanger sequencing enhanced the detection of a novel, potentially causative variant (c301 A>G; p.Ala301Asp) in exon 6 of the KCNQ4 gene. Therefore, our findings contributed to the mutation spectrum of the KCNQ4 gene and may be useful in the diagnosis and gene therapy of deafness autosomal dominant 2A.

Structure of the human K2P13.1(THIK-1) channel reveals a novel hydrophilic pore restriction and lipid cofactor site.

The halothane-inhibited K2P leak potassium channel K2P13.1 (THIK-1)1-3 is found in diverse cells1,4 including neurons1,5 and microglia6-8 where it affects surveillance6, synaptic pruning7, phagocytosis7, and inflammasome-mediated interleukin-1β release6,8,9. As with many K2Ps1,5,10-14 and other voltage-gated ion channel (VGIC) superfamily members3,15,16, polyunsaturated fatty acid (PUFA) lipids modulate K2P13.1 (THIK-1)1,5,14,17 via a poorly understood mechanism. Here, we present cryo-electronmicroscopy (cryo-EM) structures of human K2P13.1 (THIK-1) and mutants in lipid nanodiscs and detergent. These reveal that, unlike other K2Ps13,18-24, K2P13.1 (THIK-1) has a two-chamber aqueous inner cavity obstructed by a M4 transmembrane helix tyrosine (Tyr273, the flow restrictor). This hydrophilic barrier can be opened by an activatory mutation, S136P25, at natural break in the M2 transmembrane helix and by intrinsic channel dynamics. The structures also reveal a buried lipid in the P1/M4 intersubunit interface at a location, the PUFA site, that coincides with the TREK subfamily K2P modulator pocket for small molecule agonists18,26,27. This overlap, together with the effects of mutation on K2P13.1 (THIK-1) PUFA responses, indicates that the PUFA site lipids are K2P13.1 (THIK-1) cofactors. Comparison with the PUFA-responsive VGIC Kv7.1 (KCNQ1)28-31 reveals a shared role for the equivalent pore domain intersubunit interface in lipid modulation, providing a framework for dissecting the effects of PUFAs on the VGIC superfamily. Our findings reveal the unique architecture underlying K2P13.1 (THIK-1) function, highlight the importance of the P1/M4 interface in control of K2Ps by both natural and synthetic agents, and should aid development of THIK subfamily modulators for diseases such as neuroinflammation6,32 and autism6.

Anatomy of superior olivary complex and lateral lemniscus in Etruscan shrew

Based on the auditory periphery and the small head size, Etruscan shrews (Suncus etruscus) approximate ancestral mammalian conditions. The auditory brainstem in this insectivore has not been investigated. Using labelling techniques, we assessed the structures of their superior olivary complex (SOC) and the nuclei of the lateral lemniscus (NLL). There, we identified the position of the major nuclei, their input pattern, transmitter content, expression of calcium binding proteins (CaBPs) and two voltage-gated ion channels. The most prominent SOC structures were the medial nucleus of the trapezoid body (MNTB), the lateral nucleus of the trapezoid body (LNTB), the lateral superior olive (LSO) and the superior paraolivary nucleus (SPN). In the NLL, the ventral (VNLL), a specific ventrolateral VNLL (VNLLvl) cell population, the intermediate (INLL) and dorsal (DNLL) nucleus, as well as the inferior colliculus’s central aspect were discerned. INLL and VNLL were clearly separated by the differential distribution of various marker proteins. Most labelled proteins showed expression patterns comparable to rodents. However, SPN neurons were glycinergic and not GABAergic and the overall CaBPs expression was low. Next to the characterisation of the Etruscan shrew’s auditory brainstem, our work identifies conserved nuclei and indicates variable structures in a species that approximates ancestral conditions.

Conotoxins Targeting Voltage-Gated Sodium Ion Channels.

Voltage-gated sodium (NaV) channels are intimately involved in the generation and transmission of action potentials, and dysfunction of these channels may contribute to nervous system diseases, such as epilepsy, neuropathic pain, psychosis, autism, and cardiac arrhythmia. Many venom peptides selectively act on NaV channels. These include conotoxins, which are neurotoxins secreted by cone snails for prey capture or self-defense but which are also valuable pharmacological tools for the identification and/or treatment of human diseases. Typically, conotoxins contain two or three disulfide bonds, and these internal crossbraces contribute to conotoxins having compact, well defined structures and high stability. Of the conotoxins containing three disulfide bonds, some selectively target mammalian NaV channels and can block, stimulate, or modulate these channels. Such conotoxins have great potential to serve as pharmacological tools for studying the functions and characteristics of NaV channels or as drug leads for neurologic diseases related to NaV channels. Accordingly, discovering or designing conotoxins targeting NaV channels with high potency and selectivity is important. The amino acid sequences, disulfide bond connectivity, and three-dimensional structures are key factors that affect the biological activity of conotoxins, and targeted synthetic modifications of conotoxins can greatly improve their activity and selectivity. This review examines NaV channel-targeted conotoxins, focusing on their structures, activities, and designed modifications, with a view toward expanding their applications. SIGNIFICANCE STATEMENT: NaV channels are crucial in various neurologic diseases. Some conotoxins selectively target NaV channels, causing either blockade or activation, thus enabling their use as pharmacological tools for studying the channels' characteristics and functions. Conotoxins also have promising potential to be developed as drug leads. The disulfide bonds in these peptides are important for stabilizing their structures, thus leading to enhanced specificity and potency. Together, conotoxins targeting NaV channels have both immediate research value and promising future application prospects.

Mouse models of non-dystrophic and dystrophic myotonia exhibit nociplastic pain-like behaviors.

Pain is a prominent and debilitating symptom in myotonic disorders, yet its physiological mechanisms remain poorly understood. This study assessed preclinical pain-like behavior in murine models of pharmacologically induced myotonia and myotonic dystrophy type 1 (DM1). In both myotonia congenita and DM1, impairment of the CLCN1 gene, which encodes skeletal muscle voltage-gated CLC-1 chloride channels, reduces chloride ion conductance in skeletal muscle cells, leading to prolonged muscle excitability and delayed relaxation after contraction. We used the CLC-1 antagonist anthracene-9-carboxylic acid (9-AC) at intraperitoneal doses of 30 or 60 mg/kg and HSA LR20b DM1 mice to model CLC-1-induced myotonia. Our experimental approach included in vivo pain behavioral testing, ex vivo calcium imaging, and whole-cell current-clamp electrophysiology in mouse dorsal root ganglion (DRG) neurons. A single injection of 9-AC induced myotonia in mice, which persisted for several hours and resulted in long-lasting allodynic pain-like behavior. Similarly, HSA LR20b mice exhibited both allodynia and hyperalgesia. Despite these pain-like behaviors, DRG neurons did not show signs of hyperexcitability in either myotonic model. These findings suggest that myotonia induces nociplastic pain-like behavior in preclinical rodents, likely through central sensitization mechanisms rather than peripheral sensitization. This study provides insights into the pathophysiology of pain in myotonic disorders and highlights the potential of using myotonic mouse models to explore pain mechanisms and assess novel analgesics. Future research should focus on the central mechanisms involved in myotonia-induced pain and develop targeted therapies to alleviate this significant clinical burden.

Structural basis for hyperpolarization-dependent opening of human HCN1 channel

Hyperpolarization and cyclic nucleotide (HCN) activated ion channels are critical for the automaticity of action potentials in pacemaking and rhythmic electrical circuits in the human body. Unlike most voltage-gated ion channels, the HCN and related plant ion channels activate upon membrane hyperpolarization. Although functional studies have identified residues in the interface between the voltage-sensing and pore domain as crucial for inverted electromechanical coupling, the structural mechanisms for this unusual voltage-dependence remain unclear. Here, we present cryo-electron microscopy structures of human HCN1 corresponding to Closed, Open, and a putative Intermediate state. Our structures reveal that the downward motion of the gating charges past the charge transfer center is accompanied by concomitant unwinding of the inner end of the S4 and S5 helices, disrupting the tight gating interface observed in the Closed state structure. This helix-coil transition at the intracellular gating interface accompanies a concerted iris-like dilation of the pore helices and underlies the reversed voltage dependence of HCN channels.

Short-chain fatty acid valerate reduces voluntary alcohol intake in male mice

BackgroundDespite serious health and social consequences, effective intervention strategies for habitual alcohol binge drinking are lacking. The development of novel therapeutic and preventative approaches is highly desirable. Accumulating evidence in the past several years has established associations between the gut microbiome and microbial metabolites with drinking behavior, but druggable targets and their underlying mechanism of action are understudied.ResultsHere, using a drink-in-the-dark mouse model, we identified a microbiome metabolite-based novel treatment (sodium valerate) that can reduce excessive alcohol drinking. Sodium valerate is a sodium salt of valeric acid short-chain fatty acid with a similar structure as γ-aminobutyric acid (GABA). Ten days of oral sodium valerate supplementation attenuates excessive alcohol drinking by 40%, reduces blood ethanol concentration by 53%, and improves anxiety-like or approach-avoidance behavior in male mice, without affecting overall food and water intake. Mechanistically, sodium valerate supplementation increases GABA levels across stool, blood, and amygdala. It also significantly increases H4 acetylation in the amygdala of mice. Transcriptomics analysis of the amygdala revealed that sodium valerate supplementation led to changes in gene expression associated with functional pathways including potassium voltage-gated channels, inflammation, glutamate degradation, L-DOPA degradation, and psychological behaviors. 16S microbiome profiling showed that sodium valerate supplementation shifts the gut microbiome composition and decreases microbiome-derived neuroactive compounds through GABA degradation in the gut microbiome.ConclusionOur findings suggest that sodium valerate holds promise as an innovative therapeutic avenue for the reduction of habitual binge drinking, potentially through multifaceted mechanisms.4EUMY4VU8ayPcKT8VYWNUCVideo