ABSTRACT The transient receptor potential vanilloid type 1 (TRPV1) channel, a member of the TRP ion channel family, plays a crucial role in both physiological and pathological processes. This review provides an overview of the structure, biological functions, and implications of TRPV1 in autoimmune diseases. The structural characteristics of TRPV1, including its transmembrane and intracellular domains, are examined to understand its activation and modulation. In addition to its well-known role as a thermosensor in nociceptive neurons, TRPV1 has been found to have functions in immune cells where it regulates lipid synthesis and inflammatory response. The investigation of TRPV1’s involvement in autoimmune conditions such as systemic lupus erythematosus, multiple sclerosis, and rheumatoid arthritis highlights its potential as a therapeutic target. The search for selective agonists and antagonists for TRPV1 drugs is also discussed. A comprehensive understanding of TRPV1’s structure, function, and role in autoimmune diseases lays the foundation for future studies and the development of innovative therapies targeting this channel.

ABSTRACT Obesity is an established risk factor for atrial fibrillation (AF) and is associated with hypersecretion of the adipokine chemerin. Chemerin has been linked to the AF initiation and progression predominantly through Chemokine-like receptor 1(CMKLR1)-mediated signaling. This study aimed to elucidate how activation of the chemerin-CMKLR1 contributes to atrial potassium current dysregulation in obesity-related AF. Male C57BL/6J mice were divided into high-fat diet (HFD) and low-fat diet (LFD) group. Action potentials and potassium currents were recorded by whole-cell patch-clamp electrophysiology. HFD mice exhibited significantly increased susceptibility to AF. Atrial myocytes from HFD mice showed marked shortening of action potential duration, primarily due to an increase in peak repolarizing potassium current (I k,peak). The rise in I K,peak density was attributed to concurrent remodeling of its components, the transient outward potassium current (I to) and the ultrarapid delayed rectifier potassium current (I KUr). I to density increased from 30.13 ± 0.76 pA/pF to 35.42 ± 0.70 pA/pF at +70 mV, accompanied by a leftward shift of steady-state activation, a rightward shift of steady-state inactivation, faster recovery from inactivation, and upregulated Kv4.3 and KChIP2 expression. I KUr density increased from 23.95 ± 1.95 pA/pF to 30.24 ± 0.97 pA/pF at +70 mV, consistent with elevated Kv1.5 expression. These electrophysiological changes were paralleled by upregulated protein abundance of chemerin and its receptor CMKLR1 in atrial myocytes, suggesting activation of the chemerin-CMKLR1 in obese mice. Obesity-associated activation of the chemerin-CMKLR1 promotes pathological potassium current remodeling, shortens atrial APD, and contributes to obesity-related AF.

ABSTRACT 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.

ABSTRACT Seventy-five unique variants in the KCNMA1 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 KCNMA1 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 in vitro 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 KCNMA1 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.

ABSTRACT 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 Drosophila melanogaster, 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 Drosophila 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 (Aedes aegypti and Anopheles gambiae). 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 Apis mellifera 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.

ABSTRACT 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.

ABSTRACT Vascular smooth muscle ATP-sensitive potassium (KATP) channels play critical roles in modulating vascular tone and thus represent important drug targets for diverse cardiovascular pathologies. Despite extensive research efforts spanning several decades, the search for selective inhibitors that can discriminate between vascular KATP (i.e. Kir6.1/SUR2B) and pancreatic and brain KATP (i.e. Kir6.2/SUR1) channels has, until recently, been unsuccessful. Our group therefore carried out a high-throughput screen of chemically diverse compounds with the goal of discovering specific Kir6.1/SUR2B inhibitors. This screen identified several novel classes of Kir6.1/SUR2B inhibitors, including the first potent (IC50 ~100 nM) and selective inhibitor published to date, termed VU0542270. Here, we expand on this work by disclosing the identity and pharmacological properties of four additional Kir6.1/SUR2B inhibitors that are structurally unrelated to Kir to VU0542270. These inhibitors, named VU0212387, VU0543336, VU0605768, and VU0544086, inhibit Kir6.1/SUR2B with IC50 values ranging from approximately 100 nM to 1 µM and exhibit no apparent inhibitory activity toward Kir6.2/SUR1. Functional analysis of heterologously expressed subunit combinations of Kir6.1, Kir6.2, SUR1, SUR2A, and SUR2B and demonstrated that all four inhibitors act on SUR2 to induce channel inhibition. Interestingly, VU0543336 and VU0212387 exhibit paradoxical stimulatory effects on Kir6.2/SUR1 at higher doses. This study broadens our understanding of KATP channel pharmacology, generally, and reveals novel chemical matter for the development of Kir6.1/SUR2-selective drugs, specifically.

ABSTRACT In recent years, the Piezo1 channel has attracted great attention. Piezo1’s research has made remarkable advance in many aspects. However, the overall trends and knowledge structures have not been systematically investigated from a worldwide viewpoint. Therefore, it is important to fill this knowledge gap and utilize a proper tool to show the research status, hotspots, and frontiers in the Piezo1 channel. In order to better investigate the hotspots and frontiers of the Piezo1 channel research, we retrieved relevant literature from Web of Science Core Collection (WoSCC) and applied CiteSpace to perform a bibliometric analysis. Our findings might serve as a reference for future research in this area.

ABSTRACT The transient receptor potential melastatin 7 channel (TRPM7) is a nonselective cation channel highly expressed in some human cancer tissues. TRPM7 is involved in the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of cancer cells. Modulation of TRPM7 could be a promising therapeutic strategy for treating cancer; however, efficient and selective pharmacological TRPM7 modulators are lacking. In this study we investigated N- [4- (4, 6-dimethyl- 2-pyrimidinyloxy) − 3- methylphenyl] -N’ - [2 -(dimethylamino)] benzoylurea (SUD), a newly synthesized benzoylurea derivative, for its effects on cancer cell migration and EMT and on functional expression of TRPM7. Our previous studies showed that SUD induces cell cycle arrest and apoptosis of MCF-7 and BGC-823 cells (human breast cancer and gastric cancer cell lines, respectively). Here, we show that SUD significantly decreased the migration of both types of cancer cells. Moreover, SUD decreased vimentin expression and increased E-cadherin expression in both cell types, indicating that EMT is also decreased by SUD. Importantly, SUD potentially reduced the TRPM7-like current in a concentration-dependent manner and decreased TRPM7 expression through the PI3K/Akt signaling pathway. Finally, molecular docking simulations were used to investigate potential SUD binding sites on TRPM7. In summary, our research demonstrated that SUD is an effective TRPM7 inhibitor and a potential agent to suppress the metastasis of breast and gastric cancer by inhibiting TRPM7 expression and function.

ABSTRACT The mitochondrion, one of the important cellular organelles, has the major function of generating adenosine triphosphate and plays an important role in maintaining cellular homeostasis, governing signal transduction, regulating membrane potential, controlling programmed cell death and modulating cell proliferation. The dynamic balance of mitochondrial volume is an important factor required for maintaining the structural integrity of the organelle and exerting corresponding functions. Changes in the mitochondrial volume are closely reflected in a series of biological functions and pathological changes. The mitochondrial volume is controlled by the osmotic balance between the cytoplasm and the mitochondrial matrix. Thus, any disruption in the influx of the main ion, potassium, into the cells can disturb the osmotic balance between the cytoplasm and the matrix, leading to water movement between these compartments and subsequent alterations in mitochondrial volume. Recent studies have shown that mitochondrial volume homeostasis is closely implicated in a variety of diseases. In this review, we provide an overview of the main influencing factors and research progress in the field of mitochondrial volume homeostasis.