Channels (Austin, Tex.)最新文献

Increased expression of K_Ca3.1 has been found in vascular smooth muscle cells (SMC), macrophages, and T cells in atherosclerotic lesions from humans and mice. Pharmacological inhibition of K_Ca3.1 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 K_Ca3.1^-/-Apoe^-/- (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. In vitro migration assays showed a significant reduction in migration of bone marrow-derived macrophages (BMDMs) from DKO mice compared to those from Apoe^-/- mice. In vitro experiments using rat aortic smooth muscle cells revealed inhibition of PDGF-BB-induced MCP1/Ccl2 expression upon K_Ca3.1 inhibition, while activation of K_Ca3.1 further enhanced MCP1/Ccl2 expression. Both in vivo and in vitro analyses showed that silencing K_Ca3.1 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 K_Ca3.1 silencing. Overall, this study provides the first genetic evidence that K_Ca3.1 is a critical regulator of atherosclerotic lesion development and composition and provides novel mechanistic insight into the link between K_Ca3.1 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 Ca²⁺ permeability, and lower sensitivity to Mg²⁺ 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.

Intronic genetic variants within the CACNA1C gene, which encodes the pore-forming alpha 1c subunit of the Ca_v1.2 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 CACNA1C expression. Here, we demonstrate that targeted genetic deletion of Cacna1c 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 CACNA1C in astrocytes at the BBB, which could be a major factor in how intronic CACNA1C SNPs broadly increase the risk of multiple forms of major neuropsychiatric disease.

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.

The I_Ks 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 I_Ks 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 I_Ks 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 I_Ks subunits, in the presence of mefenamic acid, precede activation of K41C-I_Ks subunits due to their augmented voltage sensor kinetics.

Calcium ions play a crucial role in cardiac excitation-contraction (EC) coupling, and disruptions in Ca²⁺ homeostasis are a key factor in the development of dilated cardiomyopathy (DCM). This review aims to systematically analyze how structural and functional remodeling of Ca²⁺-handling proteins drives DCM progression and to evaluate therapeutic strategies targeting these pathways. The movement of intracellular Ca²⁺, which is regulated by transporters like SERCA2a, ryanodine receptor 2 (RYR2), and L-type Ca²⁺ channels, affects the heart's contraction and relaxation. In DCM, both structural and functional changes in the Ca²⁺-handling machinery-including t-tubule remodeling, modifications to RYR2, and dysregulation of SERCA2a and phospholamban (PLN)-disrupt Ca²⁺ cycling, worsening systolic dysfunction and ventricular dilation. For instance, reduced affinity of SERCA2a for Ca²⁺ due to imbalances in the PLN-SERCA2a interaction impairs the heart's ability to reuptake Ca²⁺ during diastole. Meanwhile, abnormalities in RYR2 contribute to arrhythmogenic Ca²⁺ leaks. Targeting these pathways for treatment has two main challenges: too much Ca²⁺ 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 Ca²⁺ 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 Ca²⁺ balance as a treatment. By integrating molecular insights with clinical phenotypes, structurally informed Ca²⁺-targeted therapies could pave the way for personalized DCM management, balancing efficacy with minimized off-target effects.

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.

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 t₁⁄₂ 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.

SCN3A, 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 SCN3A mutations to a spectrum of neurodevelopmental disorders. Here, we report two clinical cases involving rare SCN3A variants: one with a de novo 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 SCN3A variants can disrupt excitability through diverse biophysical mechanisms. Our study expands the clinical and functional landscape of SCN3A-related disorders and underscores the importance of variant-level characterization to guide diagnosis and future therapeutic strategies.