An understanding of the inner workings of the placenta is imperative to elucidate how the maternal and fetal compartments coordinate to mediate fetal development. The two compartments can be separated and studied before term in sheep, a feat not possible in humans, thus providing a valuable translational model. This study investigated differential expression of gene signaling networks in the maternal and fetal compartments of the placenta and explored the potential influence of fetal sex. On approximately gestational day 120 (term: 147 days), ewes were euthanized and fetuses removed and sexed. Placentomes [n = 5 male, n = 3 female] were collected, and caruncles (maternal) and cotyledons (fetal) were separated and sequenced to assess RNA expression. Analysis revealed 2627 differentially expressed genes (FDR<0.01, abslog2FC ≥ 2) contributing to key transcriptional differences between maternal and fetal compartments, which suggested that the maternal compartment drives extracellular signaling at the interface whereas the fetal compartment controls internal mechanisms crucial for fetal-placental development. X-chromosome inactivation equalized expression of a vast majority of X-linked genes in the fetal compartment. Additionally, the female placenta had more fine-tuned regulation of key pathways for fetal-placental development, such as DNA replication, mRNA surveillance, and RNA transport, compared to males, which had enrichment of metabolic pathways including TCA cycle and galactose metabolism. These findings, in addition to supporting differences in expression in the maternal and fetal placental compartments and the possible influence of fetal sex, offer a transcriptional platform to compare placental perturbations that occur at the maternal-fetal interface that contribute to adverse pregnancy outcomes.

Ion channels play an integral role in the normal functioning of the brain. They regulate neuronal electrical properties like synaptic activity, generation of action potentials, maintenance of resting membrane potential and neuronal plasticity, and modulate the physiology of non-neuronal cells like astrocytes and microglia. Dysregulation of ionic homeostasis and channelopathies are associated with various neurological disorders, including Alzheimer's disease (AD). Several families of ion channels are associated with AD pathophysiology and progression. In this review, we outline the current research centered around ion channel dysregulation during AD and discuss briefly the possibility of using ion channels as therapeutic targets.

Many species face extreme changes in their environment throughout the year, during which time they must modify their neuronal activity to survive. Horizontal cells (HCs) are interneurons in the goldfish (Carassius auratus) retina that demonstrate seasonal changes in membrane structure and excitability. Excitability in neurons is strongly influenced by inwardly rectifying potassium channels (Kir), suggesting that Kir in HCs may be a candidate for modulating seasonal changes. Kir channel function depends on the plasma membrane phospholipid, PIP2, to which it is bound. However, it remains unclear whether the PIP2-Kir channel interaction contributes to regulation of Kir in goldfish HCs. Using perforated patch voltage-clamp recording, we identified Kir current by inhibition with cesium (Cs+) and compared peak inward Kir current density in goldfish HCs isolated during the summer and winter months. Significantly more current was inhibited by Cs+ in winter HCs, suggesting more open Kir channels. To examine the role of PIP2 in regulating Kir, tamoxifen or activation of phospholipase C by m-3M3FBS were used to disrupt the PIP2-Kir channel interaction and subsequently reduced Kir current. Spermine, through strengthening the PIP2-Kir interaction, reduced the inhibitory effects of tamoxifen. Additionally, in current-clamp recordings, HCs treated with m-3M3FBS displayed a depolarized membrane potential (Vm) and a decrease in spontaneous Ca2+-based action potentials. We demonstrate that Kir activity is seasonally regulated in goldfish HCs and that Kir is dependent upon PIP2. Our results suggest PIP2 as a potential target for coordinating seasonal changes in the activity of neurons in the goldfish retina.

G-proteins areindispensable regulators of cellular signaling, with G-protein-gated inwardly rectifying potassium channels (GIRK) as key effectors. GNB1 encephalopathy (GNB1E) is a congenital neurological syndrome resulting from mutations in the GNB1 gene, encoding the Gβ1 subunit of G-proteins trimer (Gαβγ). GNB1E manifests as a global developmental delay, accompanied by tonus disturbances, ataxia, and epilepsy.

We utilized the Xenopus laevis oocyte heterologous expression system to investigate the impact of the L95P mutation in Gβ1 (Gβ1-L95P) on the activation of neuronal GIRK channels GIRK2 and GIRK1/2. Mutant and wild-type (WT) Gβ1 RNAs were co-injected with RNAs encoding the Gγ2 and GIRK channel subunits. The expression levels of both Gβ1 and the channel proteins, as well as the channel activity, were systematically monitored. Additionally, rigid-body docking was used to model the GIRK1/2-Gβγ complex, evaluating L95P's effect on channel-Gβγ interaction, Gβγ stability, and Gβγ-effector affinity.

. Gβ1-L95P exhibited reduced protein expression compared to WT. Even after RNA adjustments to restore comparable membrane localization, the mutant failed to effectively activate GIRK2 and GIRK1/2. Structural analysis revealed that L95 was not consistent in the Gβγ-effector interface. Thermodynamic calculations suggested that the mutation primarily destabilized Gβ1 and Gβ1-effector complex.

Gβ1-L95P leads to both reduced protein expression and impaired function in the GIRK-Gβγ interaction system. The later effect can be attributed to the changes associated with protein misfolding.

Patients with periodic paralysis have attacks of weakness precipitated by depolarization of muscle. Each form of periodic paralysis is associated with unique changes in serum K+ during attacks of weakness. In hypokalemic periodic paralysis (hypoKPP), the mutation-induced gating pore current causes weakness associated with low serum K+. In hyperkalemic periodic paralysis (hyperKPP), mutations increase a non-inactivating Na+ current (Na persistent or NaP), which causes weakness associated with elevation of extracellular K+. In Andersen-Tawil syndrome, mutations causing loss of Kir channel function cause weakness associated with either low or high K+. We developed a computer model to address two questions: (1) What mechanisms are responsible for the distinct K+ dependencies of muscle depolarization-induced weakness in the three forms of periodic paralysis? (2) Why does extracellular K+ become elevated during attacks of weakness in hyperKPP, reduced in hypoKPP, and both elevated and reduced in Andersen-Tawil syndrome? We experimentally tested the model assumptions about resting potential in normal K+ solution in hyperKPP and hypoKPP. Recreating the distinct K+ dependence of all three forms of periodic paralysis required including the K+ and voltage dependence of current through Kir channels, the extracellular K+ and intracellular Na+ dependence of the Na/K ATPase activity, and the distinct voltage dependencies of the gating pore current and NaP. A key factor determining whether muscle would depolarize was the direction of small net K+ and net Na+ fluxes, which altered ion concentrations over hours. Our findings may aid in development of novel therapy for diseases with dysregulation of muscle excitability.

Kir4.1/Kir5.1 channels play a crucial role in important physiological functions, notably in the kidneys and brain. A hallmark of these channels is the coexistence of two mechanisms of inward rectification: the classical "extrinsic" inward rectification induced by polyamines and Mg2+ blocking the pore, and a novel "intrinsic" voltage-dependent mechanism driven by K+ flux. Previous studies have shown that Kir4.1/Kir5.1 channels are modulated by the intracellular pH in the physiological range. Here, we investigated the influence of the intracellular pH on the extent of the intrinsic inward rectification of Kir4.1/Kir5.1 channels expressed in HEK-293 cells and recorded using the inside-out configuration of the patch-clamp technique. We found that mutations that are known to modulate the pH sensitivity of Kir4.1/Kir5.1 channels attenuated inward rectification. The combination of these mutations in the triple mutant channel Kir4.1(K67M)/Kir5.1(N161E-R230E) virtually abolished inward rectification at pH 7.4; however, this property was re-established at acidic pH values. Consistently, the strong inward rectification of wild-type Kir4.1/Kir5.1 channels was reduced by intracellular alkalinization and further enhanced by acidification. Altogether, these experiments indicate that the intracellular pH strongly regulates the strength of the intrinsic inward rectification. Furthermore, triple mutant channels retained the extrinsic mechanism of inward rectification at pH 7.4, as can be blocked by spermine, but lost the ability to respond to elevated levels of PIP2, unlike wild-type channels. Interestingly, whole-cell recordings of wild-type and triple mutant channels imply that the mechanism of intrinsic inward rectification is an important contributor to the overall rectification of Kir4.1/Kir5.1 channels in basal conditions.

Kappa opioid receptors (KOR) expressed by peripheral pain-sensing neurons (nociceptors) are a promising target for development of effective and safer analgesics for inflammatory pain that are devoid of central nervous system adverse effects. Here we sought to delineate the signaling pathways that underlie peripheral KOR-mediated antinociception in adult male and female Sprague-Dawley rats. In an inflammatory model of pain, local intraplantar (i.pl.) injection of pertussis toxin prevented antinociception induced by the KOR agonist, U50488, indicating that members of the Gi/o family mediate the antinociceptive response. Furthermore, i.pl. injection of the G protein-coupled inward-rectifying potassium (GIRK) channel blocker, TPNQ, as well as GIRK2 subunit-targeted siRNA abolished U50488-mediated antinociceptive behavioral responses in both male and female rats. Consistent with these data, i.pl. injection of ML297, a direct activator of GIRK1 subunit-containing channels, elicited peripheral antinociceptive behavior. It is well known that intraepidermal nerve fibers (IENF) that innervate the hindpaw propagate nociceptive signals to the spinal cord. However, recent studies suggest that keratinocytes, the major cell type in the epidermis, also play an active role in pain and sensory processing. Results from RT-qPCR, RNAscope and immunohistochemistry experiments confirmed that both KOR and GIRK are expressed in keratinocytes in the epidermal layer of the rat hindpaw. Knockdown of either KOR or GIRK2 subunits selectively in keratinocytes by i.pl. injection of shRNA plasmids, prevented the antinociceptive response to U50488. Taken together, these data suggest that KOR-mediated activation of GIRK channels in keratinocytes is required for peripherally-mediated antinociception.

The neurogenetic disorder duplication 15q syndrome (Dup15q) is characterized by a high incidence of autism spectrum disorder (ASD) and pharmacoresistant epilepsy. Standard-of-care broad-spectrum anti-seizure medications (ASM) often fail to control seizures in Dup15q, emphasizing the need for the identification of new therapeutic compounds. Previously, we generated a model of Dup15q in Drosophila melanogaster by overexpressing Dube3a in glial cells, instead of neurons. This model recapitulates the spontaneous seizures present in Dup15q patients. Here, we screened a set of FDA-approved compounds for their ability to suppress seizures in repo > Dube3a flies. We used 72 compounds from the Enzo SCREEN-WELL Ion Channel Library for primary screening of seizure suppression. Six compounds were identified that significantly reduced seizure duration. Furthermore, the compounds that passed the primary and secondary screenings were associated with K+ channels. Glial-specific knockdown of the inward rectifying potassium (Irk) 2 channel exacerbated the seizure phenotype in these animals indicating a mechanism of action for drugs that bind irk2, like minoxidil, and can suppress seizures through the rebalancing of K+ extracellularly. This pharmacological and molecular investigation further supports the role of extracellular K+ content in Dup15q seizure activation and provides a putative target for therapeutic intervention.

Dynamic control of membrane potential lies at the nexus of a wide spectrum of biological processes, ranging from the control of individual cell secretions to the orchestration of complex thought and behaviour. Electrical signals in all vascular cell types (smooth muscle cells, endothelial cells and pericytes) contribute to the control of haemodynamics and energy delivery across spatiotemporal scales and throughout all tissues. Here, our goal is to review and synthesize key studies of electrical signalling within the brain vasculature and integrate these with recent data illustrating an important electrical signalling role for pericytes, in doing so attempting to work towards a holistic description of blood flow control in the brain by vascular electrical signalling. We use this as a framework for generating further questions that we believe are important to pursue. Drawing parallels with electrical signal integration in the nervous system may facilitate deeper insights into how signalling is organized within the vasculature and how it controls blood flow at the network level.

Kir4.2 is a member of the inward rectifying potassium channel family, encoded by the KCNJ15 gene. The Kir4.2 protein is expressed in various organs including the kidneys, liver, pancreas, bladder, stomach, and lungs. Kir4.2 not only forms functional homomeric channels, but also heteromeric channels with Kir5.1. An increasing number of studies indicate that the function of the Kir4.2 channel should not be underestimated. Kir4.2 participates in cell electrotaxis chemotaxis by sensing extracellular electric fields and functions as a K + sensor in the proximal tubules of the kidney, playing a crucial role in maintaining acid-base and potassium balance. This article provides a comprehensive review of the main physiological characteristics of the Kir4.2 channel, the various pathological processes it is involved in, and the human diseases resulting from Kir4.2 dysfunction.

Background: Clear cell renal cell carcinoma (ccRCC) is marked by aggressive characteristics and a poor prognosis. The involvement of KCNJ2, an inward rectifying potassium channel, in the progression of ccRCC, along with its potential roles in immune modulation and metabolic pathways, remains unclear. Methods: The Cancer Genome Atlas (TCGA) database was utilized to analyze the gene expression, clinicopathological characteristics, and clinical relevance of KCNJ2. The prognostic value of KCNJ2 in ccRCC was evaluated with Kaplan-Meier survival analysis and receiver operating characteristic curve analyses. The TCGA-KIRC dataset was utilized to analyze tumor microenvironment (TME), focusing on tumor-infiltrating immune cells and immunomodulators. The biological functions of KCNJ2 were investigated in vitro using CCK-8, flow cytometry, wound healing, transwell, qRT-PCR, and Western blotting assays. Results: KCNJ2 expression was notably higher in ccRCC than in normal kidney tissues, with increased levels associated with advanced tumor stages. However, KCNJ2 did not exhibit obvious prognostic value. Coexpression analysis identified associations with genes implicated in energy metabolism. Analysis of the TME and immune profile indicated a link between KCNJ2 expression and immune cell infiltration, along with particular immune checkpoints. In vitro studies demonstrated that KCNJ2 overexpression enhanced cell proliferation, migration, invasion, glucose production, and ATP generation. Conclusion: KCNJ2 plays a crucial role in ccRCC progression through affecting glucose metabolism and immune responses. Our findings reveal the functional role of KCNJ2 in promoting tumor progression and metabolic reprogramming in ccRCC, highlighting its therapeutic potential as a novel target for ccRCC treatment. Further studies are essential to clarify the mechanisms by which KCNJ2 affects ccRCC biology and to evaluate its clinical relevance.

Neuropathic pain severely impacts quality of life and effective treatments are needed. To address this, the present study investigated the antihyperalgesic mechanisms of levetiracetam administered at the supraspinal level, together with its effects on ion channel activities. The ventral posterolateral nucleus of the thalamus was selected as the location for micro-injection. Thermal hyperalgesia and mechanical allodynia were assessed via in vivo experiments using the Hargreave's and e-Von Frey apparatus, respectively. Levetiracetam displayed statistically meaningful time and dose-dependent effects in the chronic constriction injury model, with statistical probability values less than 0.05. It was discovered that the antihyperalgesic effects were more pronounced in mechanical allodynia. Electrophysiological studies conducted through whole-cell patch clamp recordings indicated that levetiracetam tended to activate or increase the permeability of one or more channels for ion flow that are active only at hyperpolarized membrane potentials (-130 to -90 mV), suggesting the potential participation of hyperpolarization-activated cyclic nucleotide-gated, inwardly-rectifying K+, or G protein-gated inwardly-rectifying K+ channels. The findings could guide future drug development studies towards levetiracetam and its derivatives as effective treatments for neuropathic pain.

The dorsal horn of the spinal cord represents the first site in the central nervous system (CNS) where nociceptive signals are integrated. As a result, there has been a rapid growth in the number of studies investigating the ionic mechanisms regulating the excitability of dorsal horn neurons under normal and pathological conditions. We believe that it is time to look back and to critically examine what picture emerges from this wealth of studies. What are the actual types of neurons described in the literature based on electrophysiological criteria? Are these electrophysiologically-defined subpopulations strongly linked to specific morphological, functional, or molecular traits? Are these electrophysiological properties stable, or can they change during development or in response to peripheral injury? Here we provide an in-depth overview of both early and recent publications that explore the factors influencing dorsal horn neuronal excitability (including intrinsic membrane properties and synaptic transmission), how these factors vary across distinct subtypes of dorsal horn neurons, and how such factors are altered by peripheral nerve or tissue damage. The meta-research presented below leads to the conclusion that the dorsal horn is comprised of highly heterogeneous subpopulations in which the observed electrophysiological properties of a given neuron often fail to easily predict other properties such as biochemical phenotype or morphology. This highlights the need for future studies which can more fully interrogate the properties of dorsal horn neurons in a multi-modal manner.

Inward rectifier Kir4.1 potassium channels are abundantly expressed in cells that are important for electrolyte homeostasis. Dysregulation of Kir4.1 underlies various neurological disorders. Here, through biochemical and structural studies of full-length Kir4.1, we show that dynein light chain 1 and 2 proteins, also as known as LC8, copurify with Kir4.1 at stoichiometric levels. Direct interaction between Kir4.1 and LC8 is supported by in vitro binding assays and reiterated with native Kir4.1 proteins from mouse brain. Notably, we identify a LC8 binding motif in the unstructured N terminus of Kir4.1. Among Kir subtypes, the motif is unique to Kir4.1 and is highly conserved between Kir4.1 orthologs. Deletion of the predicted anchoring sequence (ΔTQT) resulted in loss of LC8 interaction with Kir4.1 N-terminal peptides as well as with full-length Kir4.1, suggesting that the binding site is necessary and sufficient for the interaction. Purified Kir4.1-ΔTQT mutant proteins exhibited normal channel activity in vitro, whereas WT proteins lost phosphoinositide-(4,5)-phosphate activation. Single-particle cryo-EM analysis of the full-length proteins revealed extremely heterogeneous particles, indicating deformation from the typical fourfold symmetric conformation. Additional electron density attached to the Kir4.1 tetramer, ascribed to an LC8 dimer, further supports the direct interaction between the two proteins. While the biological implications of this interaction await further elucidation, the strong conservation of the LC8 binding motif suggests its potential importance in the regulation of Kir4.1 channels.

The antiepileptic drug ethosuximide (ETX) suppresses epileptiform activity in a mouse model of GNB1 syndrome, caused by mutations in Gβ1 protein, likely through the inhibition of G-protein gated K+ (GIRK) channels. Here, we investigated the mechanism of ETX inhibition (block) of different GIRKs.

We studied ETX inhibition of GIRK channels expressed in Xenopus oocytes with or without their physiological activator, the G protein subunit dimer Gβγ. ETX binding site and mode of action were analysed using molecular dynamic (MD) simulations and kinetic modelling, and the predictions were tested by mutagenesis and functional testing.

We show that ETX is a subunit-selective, allosteric blocker of GIRKs. The potency of ETX block is increased by Gβγ, in parallel with channel activation. MD simulations and mutagenesis locate the ETX binding site in GIRK2 to a region associated with phosphatidylinositol-4,5-bisphosphate (PIP2) regulation, and suggest that ETX acts by closing the helix bundle crossing (HBC) gate and altering channel's interaction with PIP2. The apparent affinity of ETX block is highly sensitive to changes in channel gating caused by mutations in Gβ1 or GIRK subunits.

ETX block of GIRKs is allosteric, subunit-specific, and enhanced by Gβγ through an intricate network of allosteric interactions within the channel molecule. Our findings pose GIRK as a potential therapeutic target for ETX and ETX as a potent allosteric GIRK blocker and a tool for probing gating-related conformational changes in GIRK.

The potassium-chloride cotransporter 2 (KCC2) is required for neuronal development, and KCC2 dysregulation is implicated in several neurodevelopmental disorders, including schizophrenia, autism, and epilepsy. A dozen mutations in the KCC2-encoding gene, SLC12A5, are associated with these disorders, but few are fully characterized. To this end, we examined KCC2 biogenesis in a HEK293 cell model. While most of the examined disease-associated mutants matured efficiently, the L403P mutant was unable to traffic to the Golgi. Two other mutants, A191V and R857L, exhibited more subtle defects in maturation. Cell surface biotinylation assays showed that these mutants were also depleted from the cell surface. Another disease-associated variant, R952H, acquired Golgi-associated glycans yet was significantly depleted from the plasma membrane, consistent with loss of a plasma membrane-stabilizing phosphorylation site. To determine whether the ability of KCC2 to mature to the Golgi could be predicted, we employed a computational pathogenicity program, Rhapsody, which was shown in past work to predict endoplasmic reticulum-associated degradation-targeting of an unrelated ion channel. We discovered that the Rhapsody pathogenicity score correlated with relative defects in KCC2 maturation, and the algorithm outperformed two other commonly used programs. These data demonstrate the efficacy of a bioinformatic tool to predict the efficiency of KCC2 biogenesis. We also propose that Rhapsody can be used to develop hypotheses on defects associated with other disease-associated SLC12A5 alleles as they are identified.

In this study, we aimed to determine the impact of an increase in motor activity during the highly plastic period of development of the motor spinal cord and hindlimb muscles in newborn mice. A swim training regimen, consisting of two sessions per day for two days, was conducted in 1 and 2-day-old (P1, P2) pups. P3-trained pups showed a faster acquisition of a four-limb swimming pattern, accompanied by dysregulated gene expression in the lateral motor column, alterations in the intrinsic membrane properties of motoneurons (MNs) and synaptic plasticity, as well as increased axonal myelination in motor regions of the spinal cord. Network-level changes were also observed, as synaptic events in MNs and spinal noradrenaline and serotonin contents were modified by training. At the muscular level, slight changes in neuromuscular junction morphology and myosin subtype expression in hindlimb muscles were observed in trained animals. Furthermore, the temporal sequence of acquiring the adult-like swimming pattern and postural development in trained pups showed differences persisting until almost the second postnatal week. A very short motor training performed just after birth is thus able to induce functional adaptation in the developing neuromuscular system that could persist several days. This highlights the vulnerability of the neuromuscular apparatus during development and the need to evaluate carefully the impact of any given sensorimotor procedure when considering its application to improve motor development or in rehabilitation strategies.

Andersen-Tawil syndrome (ATS) is an ion channelopathy with variable penetrance for the triad of periodic paralysis, arrhythmia, and dysmorphia. Dominant-negative mutations of KCNJ2 encoding the Kir2.1 potassium channel subunit are found in 60% of ATS families. As with most channelopathies, episodic attacks in ATS are frequently triggered by environmental stresses: exercise for periodic paralysis or stress with adrenergic stimulation for arrhythmia. Fluctuations in K+, either low or high, are potent triggers for attacks of weakness in other variants of periodic paralysis (hypokalemic periodic paralysis or hyperkalemic periodic paralysis). For ATS, the [K+] dependence is less clear; with reports describing weakness in high-K+ or low-K+. Patient trials with controlled K+ challenges are not possible, due to arrhythmias. We have developed two mouse models (genetic and pharmacologic) with reduced Kir currents, to address the question of K+-sensitive loss of force. These animal models and computational simulations both show K+-dependent weakness occurs only when Kir current is <30% of wildtype. As the Kir deficit becomes more severe, the phenotype shifts from high-K+-induced weakness to a combination where either high-K+ or low-K+ triggers weakness. A K+ channel agonist, retigabine, protects muscle from K+-sensitive weakness in our mouse models of the skeletal muscle involvement in ATS.

The purpose of this review is to evaluate the current knowledge about the mechanisms by which mechanosensitive ion channels are activated by fluid shear stress in endothelial cells. We focus on three classes of endothelial ion channels that are most well studied for their sensitivity to flow and roles in mechanotransduction: inwardly rectifying K+ channels, Piezo channels, and TRPV channels. We also discuss the mechanisms by which these channels initiate and contribute to mechanosensitive signaling pathways. Three types of mechanisms have been described for flow-induced activation of ion channels: 1) through interaction with apical membrane flow sensors, such as glycocalyx, which is likely to be deformed by flow, 2) directly by sensing membrane stretch that is induced by shear stress, or 3) via flow-sensitive channel-channel or lipid channel interactions. We also demonstrate the physiological role of these channels and how they are related to cardiovascular and neurological diseases. Further studies are needed to determine how these channels function cooperatively to mediate the endothelial response to flow.

Cell lines and their corresponding expression plasmids are extensively utilized in the study of insect physiology and pathology. In this research, four single-cell cultured lines (Px4-1 to Px4-4) of Plutella xylostella were established from eggs. The promoter for the P. xylostella elongation factor 1α (PxEF1α), known for its high driving activity in cells, was cloned and used to construct expression plasmids. Dual-luciferase activity assays and EGFP expression analyses demonstrated that the PxEF1α promoter exhibited the strongest driving activity in Px4-2 cells, comparable to that of the immediate-early 1 promoter associated with the homologous region 5 enhancer (AcIE1hr5) from the Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV). In contrast, the driving activity of PxEF1α in cells derived from Spodoptera frugiperda, Trichoplusia ni, and Helicoverpa armigera was lower. Furthermore, the PxEF1α promoter was successfully employed to drive inward rectifier potassium 2A (Kir2A) expression in Px4-2 cells. The electrophysiological properties of the insect Kir2A channel were successfully characterized for the first time. It was observed that the PxKir2A channel possesses typical inward rectifier potassium channel properties and can be inhibited by nanomolar concentrations of VU625 and VU590. This study offers a novel approach for the expression and investigation of foreign gene function in insect cells and provides a valuable tool for the in-depth study of key biomolecules in P. xylostella.

Parvalbumin-positive (PV +) interneuron dysfunction is believed to be linked to autism spectrum disorder (ASD), a neurodevelopmental disorder, characterized by social deficits and stereotypical behaviors. However, the underlying mechanisms of PV + interneuron dysfunction remain largely unclear. Here, we found that a deficiency of biorientation defective 1 ( Bod1) in PV + interneuron led to an ASD-like phenotype in Pvalb-Cre; Bod1 f/f mice. Mechanistically, we identified that Bod1 deficiency induced hypoactivity of PV + interneuron and hyperactivity of calcium/calmodulin-dependent protein kinase Ⅱ alpha (CaMKⅡα) neurons in the medial prefrontal cortex (mPFC), as determined by whole-cell patch-clamp recording. Additionally, it concurrently decreased the power of high gamma oscillation, as assessed by in vivo multi-channel electrophysiological recording. Furthermore, we found that Bod1 deficiency enhanced inwardly rectifying K + current, leading to an increase in the resting membrane potential of PV + interneurons. Importantly, the gain-of-function of Bod1 improved social deficits and stereotypical behaviors in Pvalb-Cre; Bod1 f/f mice. These findings provide mechanistic insights into the PV + interneuron dysfunction and suggest new strategies for developing PV + interneuron therapies for ASD.

Inwardly rectifying potassium channels (Kir) play a key role in regulating various physiological processes. However, the structural and pharmacological mechanisms of insect Kir channels remain unclear. In this study, we show that coexpression of different Kir subunits in the same tissue did not affect the rectification properties of strongly rectifying Kir. The Kir inhibitor VU041, along with the insecticide flonicamid and its metabolite flumetnicam, were tested for their inhibitory effects on the homotetrameric Kir1 and Kir2 channels. Both Kir1 and Kir2 channels from the two insect species showed similar pharmacological responses to VU041, flonicamid, and flumetnicam. However, VU041 demonstrated significantly higher inhibitory activity than both insecticides across all four Kir channels, while flumetnicam exhibited the weakest inhibition. Molecular docking analyses indicate that the binding site of VU041 is not the same as that of flonicamid, and flumetnicam. flonicamid, and flumetnicam have binding sites similar to the ATP binding sites in cytoplasmic region of human Kir6.2, whereas VU041 is located in the pore of the ion channel, and serves as a pore blocker that inhibits Kir channels. Mutation analysis confirmed the essential roles of these residues in channel function and binding affinity. Finally, the toxicities of the three inhibitors were evaluated in N. lugens and M. persicae. VU041, a potent inhibitor of the insect Kir channel, showed lower toxicity compared to the other two inhibitors, whereas flumethoxan, which is less active on the Kir1 channel, showed higher toxicity, probably related to the different bioavailability of the different compounds. These findings suggest that the potential of targeting Kir channels as insecticidal strategies requires further evaluation.

Type 2 diabetes mellitus (T2DM) encompasses a range of clinical manifestations, with uncontrolled diabetes leading to progressive or irreversible damage to various organs. Numerous genes associated with monogenic diabetes, exhibiting classical patterns of inheritance (autosomal dominant or recessive), have been identified. Additionally, genes involved in complex diabetes, which interact with environmental factors to trigger the disease, have also been discovered. These genetic findings have raised hopes that genetic testing could enhance diagnostics, disease surveillance, treatment selection, and family counseling. However, the accurate interpretation of genetic data remains a significant challenge, as variants may not always be definitively classified as either benign or pathogenic. Research to date, however, indicates that periodic reevaluation of genetic variants in diabetes has led to more consistent findings, with biases being steadily eliminated. This has improved the interpretation of variants across diverse ethnicities. Clinical studies suggest that genetic risk information may motivate patients to adopt behaviors that promote the prevention or management of T2DM. Given that the clinical features of certain monogenic diabetes types overlap with T2DM, and considering the significant role of genetic variants in diabetes, healthcare providers caring for prediabetic patients should consider genetic testing as part of the diagnostic process. This review summarizes current knowledge of the most common genetic variants associated with T2DM, explores novel therapeutic targets, and discusses recent advancements in the pharmaceutical management of uncontrolled T2DM.

Potassium channels regulate membrane potential and diverse physiological processes, including cell migration. However, the specific function of the inwardly rectifying potassium channels in immune cell chemotaxis is unknown. Here, we identified that the inwardly rectifying potassium channel Kir7.1 (KCNJ13) maintains the resting membrane potential and is required for directional sensing during neutrophil chemotaxis. Pharmacological or genetic inhibition of Kir7.1 in neutrophils impaired direction sensing toward various chemoattractants without affecting cell polarization in multiple neutrophil models. Using genetically encoded voltage indicators, we observed oscillating depolarization of the membrane potential in protrusions in zebrafish neutrophils, and Kir7.1 is required for polarized depolarization towards the chemokine source. Focal depolarization with optogenetic tools biases pseudopod selection and induces de novo protrusions. Global hyperpolarizing neutrophils stalled cell migration. Furthermore, Kir7.1 regulates GPCR signaling activation. This work adds membrane potential to the intricate feedforward mechanism, coupling the adaptive and excitable network required to steer immune cells in complex tissue environments.

Neuropathic pain causes enduring physical discomfort and emotional distress. Conventional pharmacological treatments often provide restricted relief and may result in undesirable side effects, posing a substantial clinical challenge. Peripheral and spinal redox homeostasis plays an important role in pain processing and perception. However, the roles of oxidative stress and antioxidants in pain and analgesia on the cortical region during chronic pain remains obscure. Here we focus on the ventrolateral orbital cortex (VLO), a brain region associated with pain severity and involved in pain inhibition. Using a spared nerve injury mouse model, we observed the notable reactive oxygen species (ROS)-mediated suppression of the excitability of pyramidal cells (PYRVLO) in the VLO. Nasal application or microinjection of the natural antioxidants proanthocyanidins (PACs) to the VLO specifically increased the activity of PYRVLO and induced a significant analgesic effect. Mechanistically, PACs activate PYRVLO by inhibiting distinct potassium channels in different ways: (1) by scavenging ROS to reduce ROS-sensitive voltage-gated potassium currents and (2) by acting as a channel blocker through direct binding to the cap structure of KCNK3 to inhibit the leak potassium current (Ileak). These results reveal the role of cortical oxidative stress in central hyperalgesia and elucidate the mechanism and potential translational significance of PACs in central analgesia. These findings suggest that the effects of PACs extend beyond their commonly assumed antioxidant or anti-inflammatory effects.

Pancreatic cancer (PanCa) is one of the most lethal cancers (survival ~ 12%). As the conventional therapeutic interventions are mostly futile, a deep understanding of the disease pathophysiology is an urgent need. Ion channels, located on cell membrane, contribute significantly to cancer hallmarks, through dysregulation of various ion translocation; however, the fundamental mechanisms remain uncertain.

To identify these oncochannels in Indian cohort of PanCa, we utilized 450 K data, published in our previous study, and identified potential pathways involved. Their expressions were evaluated using TCGA data and an independent Indian paired patient cohort (n = 20). The top genes were further validated using GEO and ScRNA seq dataset. Potential target ability of KCNJ5 was identified through molecular dynamic based drug designing.

A set of 7 differentially methylated and differentially expressed genes of ion-channel proteins namely KCNJ5, CACNB2, KCNA3, KCNA6, RASA3, GABBR2 and CLIC5 were identified in Indian PanCa cohort only. KCNJ5 was significantly upregulated and associated with worse survival in Indian cohort, whereas downregulated in TCGA and other Caucasians patient populations. Two TFs controlling the KCNJ5 expression are POU2F1 and POU3F1. Few predicted small molecules targeting Kcnj5 are, Amiloride, Vernakalant hydrochloride, Dalfampridine, Glyburide and Levcromakalim. It also showed notable interactions with a steroidal anticancer agent, protodioscin.

An onco-channel gene, KCNJ5 significantly upregulated, and showing adverse survival in highly expressed KCNJ5 group in Indian cohort of PanCa, can be targeted with Amiloride, Vernakalant hydrochloride, Dalfampridine, Glyburide Levcromakalim and protodioscin. This understanding can lead to novel target identification for PanCa therapy development.

Schizophrenia (SCZ) and bipolar disorder (BD) and are severe psychiatric conditions that contribute to disability and increased healthcare costs globally. Although first-, second-, and third-generation antipsychotics are available for treating BD and SCZ, most have various side effects unrelated to their unique functions. Many antipsychotics affect K+ channels (Kv, KCa, Kir, K2P, and other channels), which change the functions of various organs. This review summarizes the biological actions of antipsychotics, including off-target side effects involving K+ channels.

Myocardial infarction (MI), a severe cardiovascular condition, is typically triggered by coronary artery disease, resulting in ischemic damage and the subsequent necrosis of the myocardium. Macrophages, known for their remarkable plasticity, are capable of exhibiting a range of phenotypes and functions as they react to diverse stimuli within their local microenvironment. In recent years, there has been an increasing number of studies on the regulation of macrophage behavior based on tissue engineering strategies, and its regulatory mechanisms deserve further investigation. This review first summarizes the effects of key regulatory factors of engineered biomaterials (including bioactive molecules, conductivity, and some microenvironmental factors) on macrophage behavior, then explores specific methods for inducing macrophage behavior through tissue engineering materials to promote myocardial repair, and summarizes the role of macrophage-host cell crosstalk in regulating inflammation, vascularization, and tissue remodeling. Finally, we propose some future challenges in regulating macrophage-material interactions and tailoring personalized biomaterials to guide macrophage phenotypes.

The peptide toxin SsTx-4 derived from venom of centipede Scolopendra subspinipes mutilans was characterized as a potent antagonist of the inwardly rectifying potassium (Kir) channel subtypes Kir1.1, Kir4.1, and Kir6.2 in our previous study. Alanine-scanning mutagenesis analysis identified key molecular determinants on the SsTx-4 toxin interacting with these Kir channels, as well as those on the Kir6.2 channel interacting with the toxin. However, the key residues on Kir1.1 and Kir4.1 channels responsible for binding SsTx-4 remain unclear. Here, using a combination of site-directed mutagenesis, patch-clamp analysis, molecular docking with AlphaFold 3, and molecular dynamic simulations, we revealed that SsTx-4 acted on the Kir channels as a pore blocker, with K13 on toxin serving as the functional pore-blocking residue and other residues on it contributing to stabilize the toxin-channel complex by binding to multiple residues on the wall of the channels' outer vestibule, involving E104 on Kir1.1; D100, L115, and F133 on Kir4.1; and E108, S113, H115, and M137 on Kir6.2. Collectively, these findings advanced our understanding on the interaction between Kir channels and this prototype Kir antagonist, providing insights that could inspire the development of more potent and specific Kir subtype blockers in the future.

Ion channels are essential for differentiation and maturation of germ cells, and even for fertilization in mammals. Different types of potassium channels have been identified, which are grouped into voltage-gated channels (Kv), ligand-gated channels (Kligand), inwardly rectifying channels (Kir), and tandem pore domain channels (K2P).

The present review includes recent findings on the role of potassium channels in sperm physiology of mammals.

While most studies conducted thus far have been focused on the physiological role of voltage- (Kv1, Kv3, and Kv7) and calcium-gated channels (SLO1 and SLO3) during sperm capacitation, especially in humans and rodents, little data about the types of potassium channels present in the plasma membrane of differentiating germ cells exist. In spite of this, recent evidence suggests that the content and regulation mechanisms of these channels vary throughout spermatogenesis. Potassium channels are also essential for the regulation of sperm cell volume during epididymal maturation and for preventing premature membrane hyperpolarization. It is important to highlight that the nature, biochemical properties, localization, and regulation mechanisms of potassium channels are species-specific. In effect, while SLO3 is the main potassium channel involved in the K+ current during sperm capacitation in rodents, different potassium channels are implicated in the K+ outflow and, thus, plasma membrane hyperpolarization during sperm capacitation in other mammalian species, such as humans and pigs.

Potassium conductance is essential for male fertility, not only during sperm capacitation but throughout the spermiogenesis and epididymal maturation.

Reduced inward rectifier potassium channel (Kir2.1) functioning is associated with heart failure and may cause Andersen-Tawil Syndrome, among others characterized by ventricular arrhythmias. Most heart failure or Andersen-Tawil Syndrome patients are treated with β-adrenoceptor antagonists (β-blockers) or sodium channel blockers; however, these do not specifically address the inward rectifier current (IK1) nor aim to improve resting membrane potential stability. Consequently, additional pharmacotherapy for heart failure and Andersen-Tawil Syndrome treatment would be highly desirable. Acute propafenone treatment at low concentrations enhances IK1 current, but it also exerts many off-target effects. Therefore, discovering and exploring new IK1-channel openers is necessary.

Effects of propafenone and 10 additional propafenone analogues were analysed. Currents were measured by single-cell patch-clamp electrophysiology. Kir2.1 protein expression levels were determined by western blot analysis and action potential characteristics were further validated in human-induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMCs). Molecular docking was performed to obtain detailed information on drug-channel interactions.

Analogues GPV0019, GPV0057 and GPV0576 strongly increased the outward component of IK1 while not affecting the Kir2.1 channel expression levels. GPV0057 did not block IKr at concentrations below 0.5 μmol L-1 nor NaV1.5 current below 1 μmol L-1. Moreover, hiPSC-CMC action potential duration was also not affected by GPV0057 at 0.5 and 1 μmol L-1. Structure analysis indicates a mechanism by which GPV0057 might enhance Kir2.1 channel activation.

GPV0057 has a strong efficiency towards increasing IK1, which makes it a good candidate to address IK1 deficiency-associated diseases.

Polycyclic aromatic hydrocarbons (PAHs) are important environmental carcinogens that can cause lung cancer. However, the underlying epigenetic mechanism during PAHs-induced lung carcinogenesis has remained largely unknown. Previously, we screened some novel epigenetic regulatory genes during 3-methylcholanthrene (3-MCA)-induced lung carcinogenesis, including the potassium inwardly rectifying channel subfamily J member 15 (KCNJ15) gene. This study aimed to investigate the expression regulation, function, and mechanism of KCNJ15 through database analysis, malignant transformed cell model, and xenograft tumor models. We found that KCNJ15 was remarkably under-expressed during lung carcinogenesis and progression. High levels of DNA methylation led to low KCNJ15 expression in 3-MCA-induced malignantly transformed HBE cells. High expression of KCNJ15 was positively correlated with good survival prognosis in lung cancer patients. KCNJ15 overexpression significantly inhibited the growth, invasion, and migration of lung cancer cells both in vitro and in vivo. Knockdown of KCNJ15 resulted in an opposite phenotype. KCNJ15 regulated the Hippo pathway by activating YAP phosphorylation and inhibiting YAP expression. There was a significant protein-protein interaction between KCNJ15 and the G protein subunit beta 1 (GNB1). GNB1 overexpression effectively reduced the effect of KCNJ15 on Hippo pathway. Our data demonstrated that KCNJ15, as a novel epigenetic silencing tumor suppressor, regulates cell growth, invasion, and migration by interaction with GNB1 protein mediating the Hippo-YAP signaling pathway during chemical-induced lung carcinogenesis and progression. It provides novel insights into epigenetic regulation mechanism during carcinogenesis induced by environmental pollutants.

Inward rectifying potassium (Kir) channels play a critical role in maintaining the resting membrane potential and cellular homeostasis. The high-resolution crystal structure of homotetrameric KirBac1.1 in detergent micelles provides a snapshot of the closed state. Similar to micelles, KirBac1.1 is reported to be in the inactive/closed conformation in POPC membranes. The slide helix of KirBac1.1 is an important structural motif that regulates channel gating. Despite the importance of slide helix in lipid-dependent gating, conflicting models have emerged for the location of slide helix and its structural dynamics in membrane mimetics is poorly understood. Here, we monitored the structural dynamics of the slide helix (residues 46-57) of KirBac1.1 in both DM micelles and POPC membranes utilizing various site-directed fluorescence approaches. We show, using ACMA-based liposome-flux assay, the cysteine mutants of the slide helix are not functional, ensuring the inactive/closed conformation in POPC membranes similar to wild-type channel. Time-resolved fluorescence and water accessibility measurements of NBD-labeled single-cysteine mutants of slide-helix residues suggest that the location of the slide helix at the interfacial region might be shallower in membranes compared to micelles. Interestingly, the slide helix of KirBac1.1 is more dynamic in the physiologically relevant membrane environment, which is accompanied by a differential hydration dynamics throughout the slide helix. Further, REES and lifetime distribution analyses suggest significant changes in conformational heterogeneity of the slide helix in membrane mimetics. Overall, our results give an insight into how membrane mimetics affect the organization and dynamics of slide helix of the closed state of KirBac1.1, and highlight the importance of lipid-protein interactions in membranes.

Chronic pain and mental health disorders, such as depression and anxiety, frequently co-occur and share underlying mechanisms involving neuronal excitability and synaptic transmission. The inwardly rectifying potassium channel 4.1 (Kir4.1), predominantly expressed in glial cells, is crucial for maintaining extracellular potassium and glutamate homeostasis. Dysregulation of Kir4.1 leads to altered neuronal activity, contributing to both chronic pain and mental health disorders. In chronic pain, downregulation of Kir4.1 impairs potassium buffering and glutamate clearance, increasing neuronal excitability and enhancing pain signaling through peripheral and central sensitization. In mental health disorders, impaired Kir4.1 function disrupts neurotrophic factor secretion and neuroinflammatory pathways, leading to mood disturbances. This review primarily summarizes findings from preclinical studies to examine the relationship between Kir4.1 and the pathogenesis of chronic pain and mental health disorders, discussing its molecular structure, expression patterns, and functional roles. Furthermore, we explore therapeutic strategies targeting Kir4.1, including pharmacological modulators and gene therapy approaches, emphasizing its potential as a novel therapeutic target.

Despite their large functional diversity and poor sequence similarity, tetrameric and pseudotetrameric potassium, sodium, calcium, and cyclic-nucleotide gated channels, as well as two-pore channels, transient receptor potential channels, and ionotropic glutamate receptor channels, share a common folding pattern of the transmembrane (TM) helices in the pore domain. In each subunit or repeat, two TM helices connected by a membrane-reentering P-loop contribute a quarter to the pore domain. The P-loop includes a membrane-descending helix, P1, which is structurally the most conserved element of these channels, and residues that contribute to the selectivity-filter region at the constriction of the ion-permeating pathway. In 24-TM channels, the pore domain is surrounded by four voltage-sensing domains, each with conserved folding of four TM helices. Hundreds of atomic-scale structures of these channels, referred to as "P-loop channels," have been obtained through x-ray crystallography or cryoelectron microscopy. The number of experimental structures of P-loop channels deposited in the PDB is rapidly increasing. AlphaFold3, RoseTTAFold, and other computational tools can be used to generate three-dimensional (3D) models of P-loop channels that lack experimental structures. While comparative structural analysis of P-loop channels is desirable, it is hindered by variations in residue numbers and 3D orientations of the channels. To address this problem, we have developed a universal residue-labeling scheme for TM helices and P-loops. We further created a database of P-loop ion channels, PLIC: www.plic3da.com, which currently includes over 400 3D-aligned structures with relabeled residues. We use this database to compare multiple 3D structures of channels from different subfamilies. The comparison, which for the first time employs statistical methods, highlights conserved and variable elements in the channels' folding, reveals irregularities, and identifies outliers that warrant further analysis.

Small-cell lung cancer (SCLC) is a recalcitrant form of cancer, representing 15% of lung cancer cases globally. SCLC is classified within the range of neuroendocrine pulmonary neoplasms, exhibiting shared morphologic, ultrastructural, immunohistochemical, and molecular genomic features. It is marked by rapid proliferation, a propensity for early metastasis, and an overall poor prognosis. The current conventional therapies involve platinum-etoposide-based chemotherapy in combination with immunotherapy. Nonetheless, the rapid emergence of therapeutic resistance continues to pose substantial difficulties. The genomic profiling of SCLC uncovers significant chromosomal rearrangements along with a considerable mutation burden, typically involving the functional inactivation of the tumor suppressor genes TP53 and RB1. Identifying biomarkers and evaluating new treatments is crucial for enhancing outcomes in patients with SCLC. Targeted therapies such as topoisomerase inhibitors, DLL3 inhibitors, HDAC inhibitors, PARP inhibitors, Chk1 inhibitors, etc., have introduced new therapeutic options for future applications. In this current review, we will attempt to outline the key molecular pathways that play a role in the development and progression of SCLC, together with a comprehensive overview of the most recent advancements in the development of novel targeted treatment strategies, as well as some ongoing clinical trials against SCLC, with the goal of improving patient outcomes.

Inwardly rectifying potassium (Kir) channels regulate essential physiological processes in insects and have been identified as potential targets for developing new insecticides. Flonicamid has been reported to inhibit Kir channels, disrupting the functions of salivary glands and renal tubules. However, the precise molecular target of flonicamid remains debated. It is unclear whether flonicamid directly targets Kir channels or acts on other sites involved in the activation of transient receptor potential vanilloid (TRPV) channels. In this study, we observed that flonicamid is more toxic to flies than its metabolite, flumetnicam. This higher toxicity is difficult to reconcile if nicotinamidase is the active target, as flonicamid does not inhibit nicotinamidase. An alternative explanation is that flonicamid and flumetnicam may have distinct targets or act on multiple targets. Furthermore, reducing the expression of three individual Kir genes in the salivary glands of D. melanogaster significantly decreased the flies' susceptibility to both flonicamid and flumetnicam. The double knockdown of Kir1 with Kir3 or Kir2 with Kir3 further reduced the flies' sensitivity to both compounds. These findings confirm the involvement of Kir channels in mediating the toxic effects of flonicamid on flies. Overall, this study offers new insights into the physiological roles of insect Kir channels and flonicamid toxicity.

Exposure to loud and/or prolonged noise damages cochlear hair cells and triggers downstream changes in synaptic and electrical activity in multiple brain regions, resulting in hearing loss and altered speech comprehension. It remains unclear however whether or not noise exposure also compromises the cochlear efferent system, a feedback pathway in the brain that fine-tunes hearing sensitivity in the cochlea. We examined the effects of noise-induced hearing loss on the spontaneous action potential (AP) firing pattern in mouse lateral olivocochlear (LOC) neurons. This spontaneous firing exhibits a characteristic burst pattern dependent on Ca2+ channels, and we therefore also examined the effects of noise-induced hearing loss on the function of these and other ion channels. The burst pattern was sustained by an interaction between inactivating Ca2+ currents contributed largely by L-type channels, and steady outward currents mediated by Ba2+-sensitive inwardly-rectifying and two-pore domain K+ channels. One week following exposure to loud broadband noise, hearing thresholds were significantly elevated, and the duration of AP bursts was increased, likely as a result of an enhanced Ca2+ current. Additional effects of noise-induced hearing loss included alteration of Ca2+-dependent inactivation of Ca2+ currents and a small elevation of outward K+ currents. We propose that noise-induced hearing loss enhances efferent activity and may thus amplify the release of neurotransmitters and neuromodulators (i.e., neuropeptides), potentially altering sensory coding within the damaged cochlea.

The Selectivity Filter (SF) in tetrameric K+ channels, has a highly conserved sequence, TVGYG, at the extracellular entry to the channel pore region. There, the backbone carbonyl oxygens from the SF residues, create a stack of K+ binding sites where dehydrated K+ binds to induce a conductive conformation of the SF. This increases intersubunit interactions and confers a higher stability to the channel against thermal denaturation. Indeed, the fit of dehydrated K+ to its binding sites is fundamental to define K+ selectivity, an important feature of these channels. Nonetheless, the SF conformation can be modified by different effector molecules. Such conformational plasticity opposes selectivity, as the SF departs from the "induced-fit" conformation required for K+ recognition. Here we studied the KirBac1.1 channel, a prokaryotic analog of inwardly rectifying K+ channels, confronted to permeant (K+) and non-permeant (Na+) cations. This channel is pH-dependent and transits from the open state at neutral pH to the closed state at acidic pH. KirBac1.1 has the orthodox TVGYG sequence at the SF and thus, its behavior should resemble that of K+-selective channels. However, we found that when at neutral pH, KirBac1.1 is only partly K+ selective and permeates this ion causing the characteristic "induced-fit" phenomenon in the SF conformation. However, it also conducts Na+ with a mechanism of ion passage reminiscent of Na+ channels, i.e., through a wide-open pore, without increasing intersubunit interactions within the tetrameric channel. Conversely, when at acidic pH, the channel completely loses selectivity and conducts both K+ and Na+ similarly, increasing intersubunit interactions through an apparent "induced-fit"-like mechanism for the two ions. These observations underline that KirBac1.1 SF is able to adopt different conformations leading to changes in selectivity and in the mechanism of ion passage.

Modern bioelectronic tools are rapidly advancing to detect electric potentials within networks of electrogenic cells, such as cardiomyocytes, neurons, and pancreatic beta cells. However, it is becoming evident that electrical signaling is not limited to the animal kingdom but may be a universal form of cell-cell communication. In this review, we discuss the existing evidence of, and tools used to collect, subcellular, single-cell and network-level electrical signals across kingdoms, including bacteria, plants, fungi, and even viruses. We discuss how cellular networks employ altered electrical "circuitry" and intercellular mechanisms across kingdoms, and we assess the functionality and scalability of cutting-edge nanobioelectronics to collect electrical signatures regardless of cell size, shape, or function. Researchers today aim to design micro- and nano-topographic structures which harness mechanosensitive membrane and cytoskeletal pathways that enable tight electrical coupling to subcellular compartments within high-throughput recording systems. Finally, we identify gaps in current knowledge of inter-species and inter-kingdom electrical signaling and propose critical milestones needed to create a central theory of electrical signaling across kingdoms. Our discussion demonstrates the need for high resolution, high throughput tools which can probe multiple, diverse cell types at once in their native or experimentally-modeled environments. These advancements will not only reveal the underlying biophysical laws governing the universal language of electrical communication, but can enable bidirectional electrical communication and manipulation of biological systems.

Pimozide is a conventional antipsychotic drug of the diphenylbutylpiperidine class, widely used for treating schizophrenia and delusional disorders and for managing motor and phonic tics in Tourette's syndrome. Pimozide is known to block dopaminergic D2 receptors and various types of voltage-gated ion channels. Among its side effects, dizziness and imbalance are the most frequently observed, which may imply an effect of the drug on the vestibular sensory receptors, the hair cells. Amniotes possess two classes of vestibular hair cells, named type I and type II hair cells, which differ in terms of signal processing and transmission. We previously reported that Pimozide [3 μM] significantly increased a delayed outward rectifying K+ current (IK,V).

In the present study, using the whole-cell patch-clamp technique we additionally show that Pimozide decreases the inward rectifying K+ current (IK,1) and the mixed Na+/K+ current (Ih) of chicken embryo type II hair cells, whereas it does not affect type I hair cells' ionic currents. Since ion channels' expression can vary depending on age and animal species, in the present study, we also tested Pimozide in adult mouse vestibular hair cells. We found that, like in the chicken embryo, Pimozide significantly increases IK,V and decreases IK,1 and Ih in type II hair cells. However, in the adult mouse, Pimozide also slightly increased the outward rectifying K+ current in type I hair cells.

While providing a possible explanation for the vestibular side effects of Pimozide in humans, its inhibitory action on mammalian hair cells might be of interest for the local treatment of vestibular disorders characterized by altered vestibular input, like Ménière's disease.