The hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4) gene has been reported to regulate the spontaneous depolarization of sinoatrial node cells. A novel HCN4 mutation (c.2036 G>A) may lead to sick sinus syndrome. The green fluorescent protein (GFP) and either the wild-type (WT) or C679Y mutant (mut) were co-transfected into HEK293 cells to investigate the impact of the mutation on HCN4 channel function. The whole-cell patch-clamp approach was utilized to record HCN4 currents. According to electrophysiological recording, the current amplitude and density generated by mut-C679Y HCN4 channels were much lower than those generated by WT channels. HCN4 channel current activation was not significantly affected by the C679Y mutation. Because of the little current, analyzing the mut channel deactivation kinetic was challenging. Thus, we have identified a novel HCN4 gene mutation that is connected to bradycardia, left ventricular noncompaction, and diverse valve-related heart conditions.

Intronic genetic variants within the gene, which encodes the pore-forming alpha 1c subunit of the Ca1.2 L-type calcium channel, are significant risk factors for a multitude of neuropsychiatric disorders. In most cases, these intronic SNPs have been associated with reduced expression. Here, we demonstrate that targeted genetic deletion of in mouse brain leads to increased astrocyte reactivity, increased expression of aquaporin 4 (AQP4) in astrocytes adjacent to the blood-brain barrier (BBB), and neuroinflammation, including changes in the levels of brain chemokines and inflammatory cytokines. Astrocytes are vital for maintaining BBB integrity, with AQP4 predominantly expressed in astrocytic endfeet where it regulates water balance in the brain. This function is critical to brain health, and deterioration of the BBB is a major feature of virtually all forms of neuropsychiatric disease. Our results highlight a previously unrecognized role for in astrocytes at the BBB, which could be a major factor in how intronic SNPs broadly increase the risk of multiple forms of major neuropsychiatric disease.

Potassium ion channel (K channel) is a crucial transmembrane protein found on cell membranes that plays a pivotal role in regulating various physiological processes such as cell membrane potential, action potential formation, and cellular excitability. Diabetes, a chronic metabolic disorder characterized by elevated blood glucose levels, can cause abnormal changes in the sensitivity and functioning of K channels over time. This can lead to an increase in intracellular K and Ca, disrupting normal cellular function and metabolism and resulting in a range of physiological and metabolic issues. Recent studies have uncovered the collaborative relationship between K channels auxiliary SUR1 and Kir6.2 gating, as well as the impact of K+ channel mutations such as KCNK11 Leu114Pro, KCNQ1Arg397Trp, KCNJ11Arg136Cys, KCNK16 Leu114Pro, and KCNMA1 Gly356Arg on diabetes mellitus and associated complications. Specifically, issues such as impaired cardiac repolarization, K, Kir, TALK, and K channel remodeling and a higher risk of arrhythmia have been emphasized. Furthermore, structural and dysfunctional K channels (K, K and Kir) can also affect the function of vascular endothelial and smooth muscle cells, leading to impaired vasomotor function, abnormal cell growth, and increased inflammation. These abnormalities can result in cardiovascular damage and lesions, and increase the risk of cardiovascular disease in diabetic individuals. These findings serve as a crucial foundation for a better understanding and addressing cardiovascular issues in patients with diabetes. Moreover, different drugs and treatments targeting the K channel may yield varying effects, offering promising prospects for preventing and managing diabetes and its related complications.

Kir (inwardly rectifying potassium) channels that play key roles in maintaining potassium homeostasis, neuronal excitability, and osmoregulation have been cloned and characterized in a variety of insects. In , three Kir channels (dKir1 dKir2, and dKir3) have been cloned and characterized, and share significant homology with mammalian Kir channels. The dKir channels are essential for various developmental processes, such as wing patterning, by modulating bone morphogenetic protein signaling pathways. Electrophysiological studies have confirmed that Kir channels function in a way analogous to their mammalian counterparts, indicating that their roles in cellular and developmental signaling have been evolutionarily conserved. Several Kir channels have also been identified and characterized in mosquitoes ( and ). Interestingly, insect Kir channel orthologs cluster into three gene "clades" or subfamilies (Kir1, Kir2, Kir3) that are distinct from mammal Kir channels based on sequence comparisons. Insect Kir channel paralogs range from two to eight Kir channel genes per species genome representing separate gene duplication events. These differences may be attributed to distinct physiological adaptations associated with their respective taxonomic groups. The honeybee genome contains two Kir channel genes, AmKir1 and AmKir2, producing six Kir channel isoforms via alternative splicing, which have been cloned and expressed in heterologous systems to study their electrophysiological properties. This review provides a comprehensive overview of current knowledge about Kir channel structures, activities, and gating as well as of their roles in insects, including evolutionary genomic aspects, molecular biology, physiological roles, and pharmacological targeting.

Microglia, the central nervous system (CNS) resident immune cells, are pivotal in regulating neurodevelopment, maintaining neural homeostasis, and mediating neuroinflammatory responses. Recent research has highlighted the importance of mechanotransduction, the process by which cells convert mechanical stimuli into biochemical signals, in regulating microglial activity. Among the various mechanosensitive channels, Piezo1 has emerged as a key player in microglia, influencing their behavior under both physiological and pathological conditions. This review focuses on the expression and role of Piezo1 in microglial cells, particularly in the context of neuroinflammation and tumorigenesis. We explore how Piezo1 mediates microglial responses to mechanical changes within the CNS, such as alterations in tissue stiffness and fluid shear stress, which are common in conditions like multiple sclerosis, Alzheimer's disease, cerebral ischemia, and gliomas. The review also discusses the potential of targeting Piezo1 for therapeutic intervention, given its involvement in the modulation of microglial activity and its impact on disease progression. This review integrates findings from recent studies to provide a comprehensive overview of Piezo1's mechanistic pathways in microglial function. These insights illuminate new possibilities for developing targeted therapies addressing CNS disorders with neuroinflammation and pathological tissue mechanics.

In the European Union, urinary incontinence (UI) affects 45% of adults during their lifetime, representing a major clinical and socio-economic burden. Failure of urethral smooth muscle (USM) to contract normally (hypo or hypercontractility) contributes to UI symptoms such as urine leakage during bladder filling or inability to urinate due to obstruction. Adequate UI treatments are lacking, partially due to a lack in understanding of cellular mechanisms underlying USM contraction. USM contractions rely on Ca signaling in urethral smooth muscle cells (USMC), resulting from Ca release from internal stores and Ca influx from extracellular sources, such as voltage-gated L-type Ca channels or store-operated Ca entry (SOCE) channels. L-type Ca channel inhibitors have inconsistent effects on urethral contractions across species, including humans, and thus solely targeting this pathway may be insufficient to modulate USM contractility. Recent animal experiments suggest SOCE mediated by Orai-STIM proteins is a critical determinant of Ca signaling in USMC, maintaining regenerative Ca release from internal stores, and thus may be a targetable pathway for influencing USM contractility. In this review, we highlight evidence suggesting SOCE as critical for Ca signaling in USMC from multiple species and propose possible mechanisms for how this occurs at the cellular level.

The hallmarks of mechanosensitive ion channels have been observed for half a century in various cell lines, although their mechanisms and molecular identities remained unknown until recently. Identification of the bona fide mammalian mechanosensory Piezo channels resulted in an explosion of research exploring the translation of mechanical cues into biochemical signals and dynamic cell morphology responses. One of the Piezo isoforms - Piezo1 - is integral in the erythrocyte (red blood cell; RBC) membrane. The exceptional flexibility of RBCs and the absence of intracellular organelles provides a unique mechanical and biochemical environment dictating specific Piezo1-functionality. The Piezo1-endowed capacity of RBCs to sense the mechanical forces acting upon them during their continuous traversal of the circulatory system has solidified a brewing step-change in our fundamental understanding of RBC biology in health and disease; that is, RBCs are not biologically inert but rather capable of complex dynamic cellular signaling. Although several lines of investigation have unearthed various regulatory mechanisms of signaling pathway activation by RBC-Piezo1, these independent studies have not yet been synthesized into a cohesive picture. The aim of the present review is to thus summarize the progress in elucidating how Piezo1 functions in the unique cellular environment of RBCs, challenge classical views of this enucleated cell, and provoke developments for future work.

K-dependent Na/Ca exchanger proteins (NCKX) are members of the CaCA superfamily with critical roles in vision, skin pigmentation, enamel formation, and neuronal functions. Despite their importance, the structural pathways governing cation transport remain unclear. To address this, we conducted a systematic study using cysteine scanning mutagenesis of human NCKX2 combined with the thiol-modifying reagents MTSET and MTSEA to probe the accessibility and functional significance of specific residues. We used homology models of outward-facing and inward-facing NCKX2 states and molecular dynamics (MD) simulations to compare and investigate residue accessibility in human NCKX2 based on the published structures of the archaeal NCK_Mj Na/Ca exchanger and the human NCX1 Na/Ca exchanger. Mutant NCKX2 proteins expressed in HEK293 cells revealed diverse effects of MTSET and MTSEA on Ca transport. Of the 146 cysteine substitutions analyzed, 35 exhibited significant changes in Ca transport activity upon treatment with MTSET, with 16 showing near-complete inhibition and six demonstrating increased activity. Residues within the cation binding sites and extracellular access channels were sensitive to modification, consistent with their critical role in ion transport, whereas intracellular residues showed minimal accessibility to MTSET but were inhibited by membrane-permeable MTSEA. Water accessibility maps from MD simulations corroborated these findings, providing a high-resolution view of water-accessible pathways. This study provides a comprehensive structural and functional map of NCKX2 ion access pathways, offering insights into the molecular basis of ion selectivity and transport. These findings highlight the key residues critical for cation binding and transport, advancing our understanding of the structural dynamics of NCKX2.

Accumulation of abdominal visceral adipose tissue (VAT) is a major risk factor for cardiovascular disease. Obesity-induced endothelial dysfunction is a precursor to severe disease, and we and others have shown that arteries embedded in VAT, but not subcutaneous adipose tissue, exhibit robust endothelial dysfunction. Using a mouse model of diet-induced obesity, we recently linked VAT from obese mice to the impairment of endothelial Kir2.1, a critical regulator of endothelial function. However, the mechanism by which VAT impairs Kir2.1 is unclear. As Kir2.1 impairment is dependent on endothelial CD36, we hypothesized that lipolytic VAT induces Kir2.1 impairment through fatty acids (FA). To test this, we first treated endothelial cells with palmitic acid (PA) to determine whether the addition of exogenous FAs recapitulated our original finding of Kir2.1 dysfunction when challenged with VAT. PA inhibited Kir2.1 assessed via whole-cell patch-clamp electrophysiology, an effect that was dependent on endothelial CD36. To determine whether inhibiting VAT lipolysis prevents Kir2.1 dysfunction in the presence of VAT in obese mice and humans, VAT was pretreated with small molecule inhibitors of adipose triglyceride lipase prior to incubating endothelial cells with adipose tissue. This approach also prevented VAT-induced impairment of endothelial Kir2.1 suggesting that VAT-derived FAs may play a role. Furthermore, inhibition of lipolysis in the VAT of obese mice and humans significantly reduced endothelial FA uptake, similar to that observed when CD36 was downregulated. These findings advance our understanding of the relationship between VAT and endothelial Kir2.1 impairment and place VAT-derived FAs as potential paracrine mediators.

A growing body of preclinical evidence indicates that the inhibition of voltage-gated Cav1.3 L-type Ca channels could be a therapeutic concept for the therapy of treatment-resistant hypertension, spinal injury and for neuroprotection in early Parkinson's disease (PD). However, available Ca-channel blockers are potent inhibitors of vascular Cav1.2 L-type channels which can cause low blood pressure as an adverse drug reaction. Therefore, Cav1.3-selective inhibitors are needed to further investigate the therapeutic potential of Cav1.3 as drug target in vivo. The bicyclic diterpene alcohol sclareol has recently been reported to exert neuroprotective properties in a mouse PD model by blocking Cav1.3 L-type channels. This study investigates the proposed Cav1.3-selectivity of sclareol compared to Cav1.2 and to other voltage-gated Ca channels in whole-cell patch-clamp experiments. Various stimulation protocols, including dopamine neuron-like firing patterns show that sclareol is neither a subtype-selective nor a potent blocker of heterologously expressed Cav1.3 and inhibits also Cav2.3 channels. Therefore, the contribution of Cav1.3 channel inhibition for the previously reported neuroprotective effects of sclareol in a mouse PD model remains unclear. In addition, cinnarizine, a vertigo therapeutic also under investigation for inhibition of Cav1.3-mediated aldosterone-secretion, inhibits Cav1.3 channels in a frequency-dependent manner, but also without relevant selectivity with respect to Cav1.3.

Jervell and Lange-Nielsen syndrome (JLNS) is characterized by congenital bilateral sensorineural hearing loss, a prolonged QT interval (QTc) on an electrocardiogram (ECG), and a high incidence of sudden death in childhood. More than 90% of JLNS cases are associated with variants in the potassium voltage-gated channel subfamily Q member 1 gene, KCNQ1 (Kv7.1). Herein, eighteen identified JLNS-related KCNQ1 variants were examined, including I145S, Y148S, G168R, Y171X, S182R, G186D, R190Q, G269D, G272D, A302V, G306V, V307V, S333F, A344A, F351L, K422S, T587M, and R594Q. Using an integrative method, we systematically characterized the biophysical properties, functional, and membrane trafficking of KCNQ1 variants distributed in different structural domains of the channel. The results demonstrated that all the variants resulted in functional deficiencies, with impaired localization in the plasma membrane being the most common cause. Although many variants exhibited normal cell surface expression consistent with protein stability, structural simulation analysis revealed that these KCNQ1 variants disrupt either KCNQ1-KCNE1 or KCNQ1-calmodulin (CaM) interaction, leading to channel dysfunction. These finding provide significant implications for the future treatment and prevention of JLNS.

, the gene encoding the voltage-gated sodium channel, Nav1.3, plays a critical role in early neuronal development. Although traditionally considered a neonatal channel, emerging evidence has linked mutations to a spectrum of neurodevelopmental disorders. Here, we report two clinical cases involving rare variants: one with a p.L209P mutation and another with compound heterozygous p.N52H and p.E1809K variants. Whole-exome sequencing and clinical phenotyping revealed overlapping features of global developmental delay, hypotonia, structural brain abnormalities, and, in one case, epilepsy and dystonia. To evaluate their functional impact, we expressed each mutant independently in CHO cells co-transfected with β1 subunits and performed whole-cell patch-clamp electrophysiology. p.N52H reduced current density and hyperpolarized activation, suggesting mixed gain- and loss-of-function effects. p.L209P selectively hyperpolarized the activation curve, while p.E1809K altered fast inactivation and accelerated recovery kinetics. These findings demonstrate that variants can disrupt excitability through diverse biophysical mechanisms. Our study expands the clinical and functional landscape of -related disorders and underscores the importance of variant-level characterization to guide diagnosis and future therapeutic strategies.

Calcium ions play a crucial role in cardiac excitation-contraction (EC) coupling, and disruptions in Ca homeostasis are a key factor in the development of dilated cardiomyopathy (DCM). This review aims to systematically analyze how structural and functional remodeling of Ca-handling proteins drives DCM progression and to evaluate therapeutic strategies targeting these pathways. The movement of intracellular Ca, which is regulated by transporters like SERCA2a, ryanodine receptor 2 (RYR2), and L-type Ca channels, affects the heart's contraction and relaxation. In DCM, both structural and functional changes in the Ca-handling machinery-including t-tubule remodeling, modifications to RYR2, and dysregulation of SERCA2a and phospholamban (PLN)-disrupt Ca cycling, worsening systolic dysfunction and ventricular dilation. For instance, reduced affinity of SERCA2a for Ca due to imbalances in the PLN-SERCA2a interaction impairs the heart's ability to reuptake Ca during diastole. Meanwhile, abnormalities in RYR2 contribute to arrhythmogenic Ca leaks. Targeting these pathways for treatment has two main challenges: too much Ca modulation can cause arrhythmias, while insufficient correction may fail to improve heart contractility. Precision interventions demand structurally resolved targets, such as stabilizing RYR2 closed states or enhancing SERCA2a activity via gene therapy, to address DCM's heterogeneous pathophysiology. Emerging strategies leveraging t-tubule restoration or isoform-specific L-type channel modulation show promise in normalizing Ca transients and halting adverse remodeling. This review compiles evidence that connects changes in EC coupling components to the progression of DCM and emphasizes the potential benefits of restoring Ca balance as a treatment. By integrating molecular insights with clinical phenotypes, structurally informed Ca-targeted therapies could pave the way for personalized DCM management, balancing efficacy with minimized off-target effects.

Seventy-five unique variants in the gene have been identified from individuals with neurological disorders. However, variant pathogenicity and evidence for disease causality are lacking in most cases. In this study, the variants N999S and E656A (rs886039469 and rs149000684, respectively) were investigated from two individuals presenting with neurological disorders. N999S was previously shown to produce strong gain-of-function (GOF) changes in homomeric BK channel properties and is found as a heterozygous allele associated with epilepsy and paroxysmal dyskinesia in humans. Although its pathogenicity has been demonstrated in heterozygous animal models, the GOF classification for N999S has not been validated in a heterozygous patient-derived tissue. Conversely, the GOF pathogenicity for E656A is based solely on homomeric channels expressed in vitro and is inconclusive. For either variant, the properties of single heterozygous channels and allele expression is unknown. In this study, we profiled the wild-type and mutant transcripts from primary human skin fibroblasts of heterozygous patients and unaffected controls and performed patch-clamp electrophysiology to characterize endogenous BK channel current properties. GOF gating was observed in single BK channel recordings from both channel types. Fibroblasts from the individual harboring the E656A variant showed decreases in the number of BK channels detected and E656A-containing transcripts compared to controls. These results show that single BK channels can be reliably detected in primary fibroblasts obtained from human skin biopsies, suggesting their utility for establishing variant pathogenicity, and reveal the BK channel expression and functional changes associated with two heterozygous patient genotypes.

Cellular mechanotransduction refers to the process through which cells perceive mechanical stimuli and subsequently translate them into biochemical signals. Key mechanosensitive ion channels encompass PIEZO, TREK-1, and TRESK. These mechanosensitive ion channels are crucial in regulating specific pathophysiological conditions, including fibrosis, tumor progression, and cellular proliferation and differentiation. Recent research indicates that PIEZO, TREK-1, and TRESK are significant contributors to various types of cancer pain by sensing mechanical stimuli, which subsequently activate internal signaling pathways. Here concentrates on advancements in research concerning PIEZO, TREK-1, and TRESK in cancer pain research, aiming to lay the groundwork for creating new therapeutic drugs that address mechanosensitive ion channels for treating cancer pain.

Increased expression of K3.1 has been found in vascular smooth muscle cells (SMC), macrophages, and T cells in atherosclerotic lesions from humans and mice. Pharmacological inhibition of K3.1 in limiting atherosclerosis has been demonstrated in mice and pigs, however direct, loss-of-function, i.e. gene silencing, studies are absent. Therefore, we generated K3.1Apoe (DKO) mice and assessed lesion development in the brachiocephalic artery (BCA) of DKO versus Apoe mice on a Western diet for 3 months. In BCAs of DKO mice, lesion size and relative stenosis were reduced by ~70% compared to Apoe mice, with no effect on medial or lumen area. Additionally, DKO mice exhibited a significant reduction in macrophage content within plaques compared to Apoe mice, independent of sex. migration assays showed a significant reduction in migration of bone marrow-derived macrophages (BMDMs) from DKO mice compared to those from Apoe mice. experiments using rat aortic smooth muscle cells revealed inhibition of PDGF-BB-induced MCP1/Ccl2 expression upon K3.1 inhibition, while activation of K3.1 further enhanced MCP1/Ccl2 expression. Both and analyses showed that silencing K3.1 had no significant effect on the collagen content of plaque. RNAseq analysis of BCA samples from DKO and Apoe mice revealed PPAR-dependent signaling as a potential key mediator of the reduction in atherosclerosis due to K3.1 silencing. Overall, this study provides the first genetic evidence that K3.1 is a critical regulator of atherosclerotic lesion development and composition and provides novel mechanistic insight into the link between K3.1 and atherosclerosis.

N-methyl-D-aspartate receptors (NMDARs) are heterotetrameric ion channels that play crucial roles in brain function. Among all the NMDAR subtypes, GluN1-N3 receptors exhibit unique agonist binding and gating properties. Unlike "conventional" GluN1-N2 receptors, which require both glycine and glutamate for activation, GluN1-N3 receptors are activated solely by glycine. Furthermore, GluN1-N3 receptors display faster desensitization, reduced Ca permeability, and lower sensitivity to Mg blockage compared to GluN1-N2 receptors. Due to these characteristics, GluN1-N3 receptors are thought to play critical roles in eliminating redundant synapses and pruning spines in early stages of brain development. Recent studies have advanced pharmacological tools for specifically targeting GluN1-N3 receptors and provided direct evidence of these glycine-activated excitatory receptors in native brain tissue. The structural basis of GluN1-N3 receptors has also been elucidated through cryo-EM and artificial intelligence. These findings highlight that GluN1-N3 receptors are not only involved in essential brain functions but also present potential targets for drug development.

The current formed by the co-assembly of KCNE1 and KCNQ1 plays an important role in cardiac repolarization. Mefenamic acid, an NSAID, is known to enhance currents and has in turn been suggested as a therapeutic starting point for the development of compounds for the treatment of long QT syndrome. Our previous examinations of mefenamic acid's action revealed that residue K41 on KCNE1 was critical for mefenamic acid's activating effect on fully KCNE1 saturated, and partially saturated channel complexes. The present study extends our previous work by incorporating the K41C-KCNE1 mutation into individual subunits to destabilize local mefenamic acid binding and explore how many of the remaining mefenamic acid-bound WT KCNE1-KCNQ1 subunits are required to support the activating action of the drug. Our results show that the potency of mefenamic acid action is reduced by the presence of K41C-KCNE1 subunits in a graded and stoichiometric, but non-linear manner. Modeling results are consistent with the idea that WT subunits, in the presence of mefenamic acid, precede activation of K41C- subunits due to their augmented voltage sensor kinetics.

Induced pluripotent stem cell (iPSC)-derived motor neurons provide a powerful platform for studying motor neuron diseases. These cells enable human-specific modeling of disease mechanisms and high-throughput drug screening. While commercially available iPSC-derived motor neurons offer a convenient alternative to time-intensive differentiation protocols, their electrophysiological properties and maturation require comprehensive evaluation to validate their utility for research and therapeutic applications. In this study, we characterized the electrophysiological properties of commercially available iPSC-derived motor neurons. Immunofluorescence confirmed the expression of motor neuron-specific biomarkers, indicating successful differentiation and maturation. Electrophysiological recordings revealed stable passive membrane properties, maturation-dependent improvements in action potential kinetics, and progressive increases in repetitive firing. Voltage-clamp analyses confirmed the functional expression of key ion channels, including high- and low-voltage-activated calcium channels, TTX-sensitive and TTX-insensitive sodium channels, and voltage-gated potassium channels. While the neurons exhibited hallmark features of motor neuron physiology, high input resistance, depolarized resting membrane potentials, and limited firing capacity suggest incomplete electrical maturation. Altogether, these findings underscore the potential of commercially available iPSC-derived motor neurons as a practical resource for MND research, while highlighting the need for optimized protocols to support prolonged culture and full maturation.

Kv10.1 is a voltage-gated K channel whose structure-function relationships remain incompletely understood, and whose ectopic expression is linked to tumorigenesis. We have recently shown that the antiarrhythmic drug amiodarone inhibits both the K current and the characteristic Cole-Moore shift of Kv10.1. Here, we examined whether the amiodarone derivative KB130015 similarly modulates Kv10.1 function. Low micromolar concentrations of KB130015 markedly accelerated current activation across all tested holding potentials and fully abolished the Cole-Moore shift. The t⁄ reduction induced by KB130015 was voltage independent. KB130015 also slowed channel deactivation to a similar extent at all voltages and shifted the G-V relationship toward more negative potentials without altering its slope. Despite these pronounced gating effects, current amplitude increased only slightly and showed minimal dependence on KB130015 concentration. Notably, KB130015 enhanced the inhibitory effect of amiodarone on K current. These results identify KB130015 as a potent modulator of Kv10.1 gating that also potentiates amiodarone-mediated inhibition.