Ion Channel Activity Research Articles

Ion channels in acinar cells in acute pancreatitis: crosstalk of calcium, iron, and copper signals

The initial stages of acute pancreatitis (AP) are characterized by a significant event - acinar ductal metaplasia (ADM). This process is a crucial feature of both acute and chronic pancreatitis, serving as the first step in the development of pancreatic cancer. Ion channels are integral transmembrane proteins that play a pivotal role in numerous biological processes by modulating ion flux. In many diseases, the expression and activity of ion channels are often dysregulated. Metal ions, including calcium ions (Ca2+), ferrous ions (Fe2+), and Copper ions (Cu2+), assume a distinctive role in cellular metabolism. These ions possess specific biological properties relevant to cellular function. However, the interactions among these ions exacerbate the imbalance within the intracellular environment, resulting in cellular damage and influencing the progression of AP. A more in-depth investigation into the mechanisms by which these ions interact with acinar cells is essential for elucidating AP’s pathogenesis and identifying novel therapeutic strategies. Currently, treatment for AP primarily focuses on pain relief, complications prevention, and prognosis improvement. There are limited specific treatments targeting acinous cell dedifferentiation or ion imbalance. This study aims to investigate potential therapeutic strategies by examining ion crosstalk within acinar cells in the context of acute pancreatitis.

Mechanistic Insights Into Redox Damage of the Podocyte in Hypertension.

Podocytes are specialized cells within the glomerular filtration barrier, which are crucial for maintaining glomerular structural integrity and convective ultrafiltration. Podocytes exhibit a unique arborized morphology with foot processes interfacing by slit diaphragms, ladder-like, multimolecular sieves, which provide size and charge selectivity for ultrafiltration and transmembrane signaling. Podocyte dysfunction, resulting from oxidative stress, dysregulated prosurvival signaling, or structural damage, can drive the development of proteinuria and glomerulosclerosis in hypertensive nephropathy. Functionally, podocyte injury leads to actin cytoskeleton rearrangement, foot process effacement, dysregulated slit diaphragm protein expression, and impaired ultrafiltration. Notably, the renin-angiotensin system plays a pivotal role in podocyte function, with beneficial AT2R (angiotensin receptor 2)-mediated nitric oxide (NO) signaling to counteract AT1R (angiotensin receptor 1)-driven calcium (Ca2+) influx and oxidative stress. Disruption of this balance contributes significantly to podocyte dysfunction and drives albuminuria, a marker of kidney damage and overall disease progression. Oxidative stress can also lead to sustained ion channel-mediated Ca2+ influx and precipitate cytoskeletal disorganization. The complex interplay between GPCR signaling, ion channel activation, and redox injury pathways underscores the need for additional research aimed at identifying targeted therapies to protect podocytes and preserve glomerular function. Earlier detection of albuminuria and podocyte injury through routine noninvasive diagnostics will also be critical in populations at the highest risk for the development of hypertensive kidney disease. In this review, we highlight the established mechanisms of oxidative stress-mediated podocyte damage in proteinuric kidney diseases, with an emphasis on a hypertensive renal injury. We will also consider emerging therapies that have the potential to selectively protect podocytes from redox-related injury.

The neurobiological mechanisms of photoperiod impact on brain functions: a comprehensive review.

Variations in day length, or photoperiodism, whether natural or artificial light, significantly impact biological, physiological, and behavioral processes within the brain. Both natural and artificial light sources are environmental factors that significantly influence brain functions and mental well-being. Photoperiodism is a phenomenon, occurring either over a 24 h cycle or seasonally and denotes all biological responses of humans and animals to these fluctuations in day and night length. Conversely, artificial light occurrence refers to the presence of light during nighttime hours and/or its absence during the daytime (unnaturally long and short days, respectively). Light at night, which is a form of light pollution, is prevalent in many societies, especially common in certain emergency occupations. Moreover, individuals with certain mental disorders, such as depression, often exhibit a preference for darkness over daytime light. Nevertheless, disturbances in light patterns can have negative consequences, impacting brain performance through similar mechanisms albeit with varying degrees of severity. Furthermore, changes in day length lead to alterations in the activity of receptors, proteins, ion channels, and molecular signaling pathways, all of which can impact brain health. This review aims to summarize the mechanisms by which day length influences brain functions through neural circuits, hormonal systems, neurochemical processes, cellular activity, and even molecular signaling pathways.

The cumulative effect of compound heterozygous variants in TRPV3 caused Olmsted syndrome

BackgroundOlmsted syndrome (OS) is a rare genodermatosis predominantly inherited in an autosomal dominant manner, typically arising from gain-of-function (GOF) variants in the transient receptor potential channel vanilloid 3 (TRPV3). ObjectiveThis study aims to investigate potential mechanisms underlying OS in two cases presenting with an autosomal recessive inheritance pattern. MethodsNext-generation sequencing panel was employed to identify TRPV3 variants. TRPV3 plasmids carrying specific point variations were generated and transiently transfected into HEK293T cells. Electrophysiological patch-clamp techniques were utilized to record voltage-activated and ligand-activated currents. Celltiter-Glo luminescent assay was employed to analyze the cell viabilities. ResultsCompound heterozygous variants, c.1563G>C (p.W521C) and c.1376C>T (p.S459L), as well as c.1773G>C (p.L591F) and c.2186G>A (p.R729Q), were identified in the two OS patients respectively. Electrophysiological analysis of ligand-induced activation of TRPV3 variants demonstrated the closest correlation with clinical manifestations. All four variants displayed GOF channel activity characterized by increased sensitivity. Notably, W521C and L591F exhibited both heightened sensitivity and lower EC50 values for the TRPV3 agonist. Co-transfection with wild-type TRPV3 plasmids significantly rescued these effects. Cells co-transfected with the corresponding compound heterozygous variants exhibited intermediate electrophysiological characteristics. ConclusionsIn this study, we present two cases of OS by autosomal-recessive inheritance of TPRV3 variants. This study presents a notable observation of compound heterozygous GOF variants in TRPV3, highlighting their cumulative impact on clinical manifestations. Additionally, we advocate for the use of ligand-dependent ion channel activity assays to assess the pathogenicity of TRPV3 variants in OS.

Functions and mechanisms of CDPKs in plant responses to abiotic stress

Calcium-dependent protein kinases (CDPKs/CPKs) are members of the Ca2+-sensitive Ser/Thr protein kinase family and play a crucial role in plant growth and development and responses to abiotic stress. CDPKs are capable of rapidly sensing changes in intracellular Ca2+ signals and recognizing and phosphorylating specific substrates, thereby transmitting and amplifying Ca2+ signal cascades downstream. They are involved in plant responses to stress conditions such as drought, saline-alkali stress, and injuries and regulate plant growth and development, gene expression, ion channel activity, and stomatal movement. The autophosphorylation of CDPKs can affect their activities and substrate specificity. CDPKs have the ability to bind to and phosphorylate multiple substrates. In addition to participating in respiratory burst oxidase homolog (RBOH), mitogen-activated protein kinase (MAPK), and plant hormone signaling pathways, CDPKs can also bind to 14-3-3 proteins, which enables the regulation of plant responses to stress and promotes plant growth and development. This paper summarized the research findings on the discovery, structure, classification, and roles of CDPKs in plant responses to stress and proposed the future research directions, aiming to provide the genetic resources and a theoretical basis for improving the stress tolerance of crops.

Cryo-EM structure of the zinc-activated channel (ZAC) in the Cys-loop receptor superfamily

Cys-loop receptors are a large superfamily of pentameric ligand-gated ion channels with various physiological roles, especially in neurotransmission in the central nervous system. Among them, zinc-activated channel (ZAC) is a Zn2+-activated ion channel that is widely expressed in the human body and is conserved among eukaryotes. Due to its gating by extracellular Zn2+, ZAC has been considered a Zn2+ sensor, but it has undergone minimal structural and functional characterization since its molecular cloning. Among the families in the Cys-loop receptor superfamily, only the structure of ZAC has yet to be determined. Here, we determined the cryo-EM structure of ZAC in the apo state and performed structure-based mutation analyses. We identified a few residues in the extracellular domain whose mutations had a mild impact on Zn2+ sensitivity. The constriction site in the ion-conducting pore differs from the one in other Cys-loop receptor structures, and further mutational analysis identified a key residue that is important for ion selectivity. In summary, our work provides a structural framework for understanding the ion-conducting mechanism of ZAC.

Prediction of conformational states in a coronavirus channel using Alphafold-2 and DeepMSA2: Strengths and limitations

The envelope (E) protein is present in all coronavirus genera. This protein can form pentameric oligomers with ion channel activity which have been proposed as a possible therapeutic target. However, high resolution structures of E channels are limited to those of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), responsible for the recent COVID-19 pandemic. In the present work, we used Alphafold-2 (AF2), in ColabFold without templates, to predict the transmembrane domain (TMD) structure of six E-channels representative of genera alpha-, beta- and gamma-coronaviruses in the Coronaviridae family. High-confidence models were produced in all cases when combining multiple sequence alignments (MSAs) obtained from DeepMSA2. Overall, AF2 predicted at least two possible orientations of the α-helices in E-TMD channels: one where a conserved polar residue (Asn-15 in the SARS sequence) is oriented towards the center of the channel, ‘polar-in’, and one where this residue is in an interhelical orientation ‘polar-inter’. For the SARS models, the comparison with the two experimental models ‘closed’ (PDB: 7K3G) and ‘open’ (PDB: 8SUZ) is described, and suggests a ∼60˚ α-helix rotation mechanism involving either the full TMD or only its N-terminal half, to allow the passage of ions. While the results obtained are not identical to the two high resolution models available, they suggest various conformational states with striking similarities to those models. We believe these results can be further optimized by means of MSA subsampling, and guide future high resolution structural studies in these and other viral channels.

Electrically-stimulated cellular and tissue events are coordinated through ion channel-mediated calcium influx and chromatin modifications across the cytosol-nucleus space

Electrical stimulation (ES) through biomaterials and devices has been implicated in activating diverse cell behaviors while facilitating tissue healing process. Despite its significance in modulating biological events, the mechanisms governing ES-activated cellular phenomena remain largely elusive. Here, we demonstrated that millisecond-pulsed temporal ES profoundly impacted a spectrum of cellular events across the membrane-cytosol-nuclear space. These include activated ion channels, intracellular calcium influx, actomyosin contractility, cell migration and proliferation, and secretome release. Such events were coordinated mainly through ES-activated ion channels and calcium oscillation dynamics. Notably, ES increased the chromatin accessibility of genes, particularly those associated with the ES-activated cellular events, underscoring the significance of epigenetic changes in ES-induced behavioral outcomes. We identified histone acetylation (mediated by histone acetyltransferases), among other chromatin modifications, is key in reshaping the chromatin landscape upon ES. These observations were further validated through experiments involving ex vivo skin tissue samples, including activated ion channels and calcium influx, increased cell proliferation and actomyosin contractility, elevated secretome profile, and more accessible chromatin structure following ES. This work provides novel insights into the mechanisms underlying ES-activated cell and tissue events, ultimately guiding design principles for the development of electrical devices and materials effective for tissue repair and wound healing.

Molecular mechanisms and diagnostic model of glioma-related epilepsy

Epilepsy is one of the most common symptoms in patients with gliomas; however, the mechanisms underlying its interaction are not yet clear. Moreover, epidemiological studies have not accurately identified patients with glioma-related epilepsy (GRE), and there is an urgent need to identify the molecular mechanisms and markers of its occurrence. We analyzed the demographics, transcriptome, whole-genome, and methylation sequences of 997 patients with glioma, to determine the genetic differences between glioma and GRE patients and to determine the upregulated molecular function, cellular composition, biological processes involved, signaling pathways, and immune cell infiltration. Twelve machine learning algorithms were refined into 113 combinatorial algorithms for building diagnostic recognition models. A total of 342 patients with GRE were identified with WHO grade 2 (174), grade 3 (107), and grade 4 (61). The mean age of the patients with GREs, with IDH mutations (n = 217 [63%]) and 1p19q non-codeletion (n = 169 [49%]), was 38 years old. GRE molecular functions were mainly passive transmembrane transporter protein activity, ion channel activity, and gated channel activity. Cellular components were enriched in the cation-channel and transmembrane transporter complexes. Cerebral cortical development regulates the membrane potential and synaptic organization as major biological processes. The signaling pathways mainly focused on cholinergic, GABAergic, and glutamatergic synapses. LASSO, combined with Random Forest, was the best diagnostic model and identified nine diagnostic genes. This study provides new insights and future perspectives for resolving the molecular mechanisms of GRE.

Voltage- and Ca2+-inducible PLC activity for analyzing PI(4,5)P2 sensitivity of ion channels in Xenopus oocytes.

Phosphatidylinositol 4,5-bisphosphate (PIP2) is a key membrane lipid regulating various ion channel activities. Currently, several molecular tools are used to modulate PIP2 levels, each of which has distinct advantages and drawbacks. In this study, we proposed a novel methodology using heterologous Xenopus oocytes to precisely manipulate PIP2 levels using phospholipase C (PLC)-ζ, which hydrolyzes PIP2. Xenopus oocytes injected with PLCζ exhibited notable hyperpolarization-induced Ca2+ influx driven by the increased driving force of Ca2+. High Ca2+ sensitivity of PLCζ facilitated hyperpolarization-induced PLC activity in Xenopus oocytes that was voltage- and Ca2+-dependent. This study demonstrated the regulatory capacity of PLCζ in modulating PIP2-sensitive ion channels, such as the KCNQ2/3 and GIRK channels, in a voltage- and Ca2+-dependent manner. Moreover, activation pathway of PLCζ only requires a two-electrode voltage clamp setup, making it a convenient molecular tool to manipulate PIP2 levels in combination with a voltage-sensing phosphatase (VSP). PLCζ has distinct characteristics and advantages compared to VSP: (1) Hyperpolarization, but not depolarization, reduced the PIP2 levels, (2) PIP2 levels were decreased without any increase in phosphatidylinositol 4-monophosphate (PIP) levels, and (3) PIP2 levels were reduced by Ca2+ administration. Therefore, PLCζ effectively supports understanding how PIP2 regulates ion channels, alongside VSP. Overall, this study highlights the unique characteristics of PLCζ and its distinct advantages in analyzing ion channel regulation by PIP2 and the PLC pathway in Xenopus oocytes.

Melatonin inhibits voltage-gated potassium KV4.2 channels and negatively regulates melatonin secretion in rat pineal glands.

Melatonin is synthesized in and secreted from the pineal glands and regulates circadian rhythms. Although melatonin has been reported to modulate the activity of ion channels in several tissues, its effects on pineal ion channels remain unclear. In the present study, the effects of melatonin on voltage-gated K+ (KV) channels, which play a role in regulating the resting membrane potential, were examined in rat pinealocytes. The application of melatonin reduced pineal KV currents in a concentration-dependent manner (IC50 = 309 µM). An expression analysis revealed that KV4.2 channels were highly expressed in rat pineal glands. Melatonin-sensitive currents were abolished by the small interfering RNA knockdown of KV4.2 channels in rat pinealocytes. In human embryonic kidney 293 (HEK293) cells expressing KV4.2 channels, melatonin decreased outward currents (IC50 = 479 µM). Inhibitory effects were mediated by a shift in the voltage dependence of steady-state inactivation in a hyperpolarizing direction. This inhibition was observed even in the presence of 100 nM luzindole, an antagonist of melatonin receptors. Melatonin also blocked the activity of KV4.3, KV1.1, and KV1.5 channels in reconstituted HEK293 cells. The application of 1 mM melatonin caused membrane depolarization in rat pinealocytes. Furthermore, KV4.2 channel inhibition by 5 mM 4-aminopyridine attenuated melatonin secretion induced by 1 µM noradrenaline in rat pineal glands. These results strongly suggest that melatonin directly inhibited KV4.2 channels and caused membrane depolarization in pinealocytes, resulting in a decrease in melatonin secretion through parasympathetic signaling pathway. This mechanism may function as a negative-feedback mechanism of melatonin secretion in pineal glands. NEW & NOTEWORTHY Melatonin is a hormone that is synthesized in and secreted from the pineal glands, which regulates circadian rhythms. However, the effects of melatonin on pineal ion channels remain unclear. The present study demonstrated that melatonin directly inhibited voltage-gated potassium KV4.2 channels, which are highly expressed in rat pinealocytes, and induced membrane depolarization, resulting in a decrease in melatonin secretion. This mechanism may function as a negative-feedback mechanism of melatonin secretion in pineal glands.

Direct conversion of human umbilical cord mesenchymal stem cells into dopaminergic neurons for Parkinson's disease treatment

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor deficits due to the depletion of nigrostriatal dopamine. Stem cell differentiation therapy emerges as a promising treatment option for sustained symptom relief. In this study, we successfully developed a one-step differentiation system using the YFBP cocktail (Y27632, Forskolin, SB431542, and SP600125) to effectively convert human umbilical cord mesenchymal stem cells (hUCMSCs) into dopaminergic neurons without genetic modification. This approach addresses the challenge of rapidly and safely generating functional neurons on a large scale. After a 7-day induction period, over 80 % of the cells were double-positive for TUBB3 and NEUN. Transcriptome analysis revealed the dual roles of the cocktail in inducing fate erasure in mesenchymal stem cells and activating the neuronal program. Notably, these chemically induced cells (CiNs) did not express HLA class II genes, preserving their immune-privileged status. Further study indicated that YFBP significantly downregulated p53 signaling and accelerated the differentiation process when Pifithrin-α, a p53 signaling inhibitor, was applied. Additionally, Wnt/β-catenin signaling was transiently activated within one day, but the prolonged activation hindered the neuronal differentiation of hUCMSCs. Upon transplantation into the striatum of mice, CiNs survived well and tested positive for dopaminergic neuron markers. They exhibited typical action potentials and sodium and potassium ion channel activity, demonstrating neuronal electrophysiological activity. Furthermore, CiNs treatment significantly increased the number of tyrosine hydroxylase-positive cells and the concentration of dopamine in the striatum, effectively ameliorating movement disorders in PD mice. Overall, our study provides a secure and reliable framework for cell replacement therapy for Parkinson's disease.

Endosomal fusion of pH-dependent enveloped viruses requires ion channel TRPM7

The majority of viruses classified as pandemic threats are enveloped viruses which enter the cell through receptor-mediated endocytosis and take advantage of endosomal acidification to activate their fusion machinery. Here we report that the endosomal fusion of low pH-requiring viruses is highly dependent on TRPM7, a widely expressed TRP channel that is located on the plasma membrane and in intracellular vesicles. Using several viral infection systems expressing the envelope glycoproteins of various viruses, we find that loss of TRPM7 protects cells from infection by Lassa, LCMV, Ebola, Influenza, MERS, SARS-CoV-1, and SARS-CoV-2. TRPM7 ion channel activity is intrinsically necessary to acidify virus-laden endosomes but is expendable for several other endosomal acidification pathways. We propose a model wherein TRPM7 ion channel activity provides a countercurrent of cations from endosomal lumen to cytosol necessary to sustain the pumping of protons into these virus-laden endosomes. This study demonstrates the possibility of developing a broad-spectrum, TRPM7-targeting antiviral drug to subvert the endosomal fusion of low pH-dependent enveloped viruses.

Methylcobalamin as a candidate for chronic peripheral neuropathic pain therapy: review of molecular pharmacology actiona.

Chronic peripheral neuropathic pain therapy currently focuses on modulating neuroinflammatory conditions. Methylcobalamin (MeCbl), a neuroregenerative agent, modulates neuroinflammation. This review aimed to explore the molecular pharmacology action of MeCbl as a chronic peripheral neuropathic pain therapeutic agent. MeCbl plays a role in various cellular processes and may have therapeutic potential in neurodegenerative diseases. Intracellular MeCbl modulates inflammation by regulating the activity of T lymphocytes and natural killer cells as well as secretion of inflammatory cytokines, namely, tumor necrosis factor-α, interleukin-6, interleukin-1β, epidermal growth factor, and neuronal growth factor. MeCbl can reduce pain symptoms in chronic neuropathic pain conditions by decreasing excitation and hyperpolarization-induced ion channel activity in medium-sized dorsal root ganglion (DRG) neurons and the expression of transient receptor potential ankyrin 1, transient receptor potential cation channel subfamily M member 8, phosphorylated p38MAPK, transient receptor potential cation channel subfamily V members 1 and 4 in the DRG, and the voltage-gated sodium channel in axons.

Extracellular vesicles from cancer cell lines of different origins drive the phenotype of normal oral fibroblasts in a CAF-like direction.

Normal oral fibroblasts (NOFs) are located in the connective tissue of the oral mucosa. The NOFs play an important role in wound healing, tumor progression, and metastasis. They are subjected to influence by external and internal stimuli, among them extracellular vesicles (EVs), that are considered as important players in cell to cell communication, especially in carcinogenesis and metastatic processes. During tumorigenesis, stromal NOFs may undergo activation into cancer-associated fibroblasts (CAFs) that modify their phenotype to provide pro-oncogenic signals that in turn facilitate tumor initiation, progression, and metastasis. The aim of the study was to reveal the effect of EVs derived from local (oral squamous cell carcinoma - OSCC) and distant (pancreatic adenocarcinoma - PDAC; malignant melanoma brain metastasis - MBM) cancer origin on NOFs and their possible change into a CAF-like direction. The effect of each of the cancer EV types on NOFs proliferation, viability, and migration was tested. Also, changes in gene expression of the well-established CAF biomarkers ACTA2, FAP, PDGFR, and two putative CAF biomarkers, the Ca2+- activated ion channels ANO1 and KCNMA, were studied. Obtained results indicate that NOFs receive and process signals transmitted by EVs originating from both OSCC, PDAC, and MBM. The fibroblast response was dependent on EV origin and concentration, and duration of EV exposure. The present results indicate that the molecular cargo of the EVs direct NOFs towards a pro-tumorigenic phenotype.

Kemin capsule ameliorates post-infectious cough by modulating the PI3K/AKT signaling pathway and TRPA1/TRPV1 channels

Ethnopharmacological relevanceKemin capsule (KMC), as an innovative traditional Chinese medicine (TCM), has shown excellent efficacy in treating PIC in China. The post-infectious cough (PIC) is a common condition in pediatrics, and the inflammatory responses to PIC are intricately linked to the immune mechanisms of the host. However, the precise mechanisms involved remain uncertain. Aim of studyThe objective of this research is to investigate the mechanisms by which KMC treats PIC using a combination of UPLC-MS, bioinformatics, network pharmacology, and molecular docking. The study's findings will be corroborated through in vitro and in vivo experiments. Materials and methodsThis study identified the main components of KMC using UPLC-MS. The mechanism by which these capsules treat PIC was explored through transcriptomics, network pharmacology, and molecular docking. PIC model in Balb/c mice was induced with respiratory syncytial virus (RSV) at a titer of 10^5.5 TCID50/mL. From day 14 post-infection, the mice were orally administered the capsules at doses of 0.3, 0.6, and 1.2 g/kg for two weeks. Cough was stimulated with capsaicin at 10^-4 mol/mL, and the effects on PIC mice were measured by cough frequency, latency, ELISA, and H&E staining. Expression levels of transient receptor potential (TRP) channel proteins and the PI3K/AKT signaling pathway were analyzed using RT-qPCR, immunohistochemistry (IHC), and western blot (WB). The effect of KMC on A549 cells proliferation in vitro was also assessed. ResultsThe therapeutic efficacy of KMC is potentially exerted through its inherent bioactive constituents, including deoxyandrographolide, quercetin, and chryseriol. These compounds are hypothesized to modulate the PI3K/AKT signaling pathway and influence the function of TRP channel proteins, consequently mitigating the pathological state associated with PIC. In vivo experiments have demonstrated that KMC significantly reduces the frequency of coughs and extends the cough latency period in mice with PIC. KMC mitigates airway inflammation by suppressing the production of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-6. The expression or phosphorylation levels of key regulators in the PI3K/AKT/TRP axis in mouse lung tissue, including PI3K, AKT, NF-κB p65, TLR4, STAT3, TRPV1, TRPA1 were significantly reduced. ConclusionKMC exerts its therapeutic effect on PIC by dampening the activation of the PI3K/AKT signaling pathway and the activity of TRPA1 and TRPV1 ion channels.

Neural stimulation and modulation with sub-cellular precision by optomechanical bio-dart

Neural stimulation and modulation at high spatial resolution are crucial for mediating neuronal signaling and plasticity, aiding in a better understanding of neuronal dysfunction and neurodegenerative diseases. However, developing a biocompatible and precisely controllable technique for accurate and effective stimulation and modulation of neurons at the subcellular level is highly challenging. Here, we report an optomechanical method for neural stimulation and modulation with subcellular precision using optically controlled bio-darts. The bio-dart is obtained from the tip of sunflower pollen grain and can generate transient pressure on the cell membrane with submicrometer spatial resolution when propelled by optical scattering force controlled with an optical fiber probe, which results in precision neural stimulation via precisely activation of membrane mechanosensitive ion channel. Importantly, controllable modulation of a single neuronal cell, even down to subcellular neuronal structures such as dendrites, axons, and soma, can be achieved. This bio-dart can also serve as a drug delivery tool for multifunctional neural stimulation and modulation. Remarkably, our optomechanical bio-darts can also be used for in vivo neural stimulation in larval zebrafish. This strategy provides a novel approach for neural stimulation and modulation with sub-cellular precision, paving the way for high-precision neuronal plasticity and neuromodulation.

Computational investigation in inhibitory effects of amantadine on classical swine fever virus p7 ion channel activity

Classical swine fever virus (CSFV) p7 viroporin plays crucial roles in cellular ion balance and permeabilization. The antiviral drug amantadine effectively inhibits viral replication by blocking the activity of CSFV p7 viroporin. However, little information is available for the binding mode of amantadine with CSFV p7 viroporin, due to the lack of a known polymer structure for CSFV p7. In this study, we employed AlphaFold2 to predict CSFV p7 structures. Subsequently, we conducted a docking study to investigate the binding sites of amantadine to CSFV p7. Computational analysis showed that CSFV p7 forms a pore channel in a hexameric structure. Furthermore, molecular dynamics (MD) simulations and mutant analyses further suggest that CSFV p7 likely exists as a hexamer. Docking studies and MD simulations showed that amantadine interacts with the hydrophibic regions of tetramer and pentamer, as well as with the hydrophobic pore channel of the hexamer. Considering the potential hexameric assembly of CSFV p7, along with docking results, MD simulations, and the characteristics of the gated ion channels, we propose a model of CSFV p7 ion channel based on its hexameric configuration. In this model, residues E21, Y25, and R34 are suggested to selectively recruit and dehydrate ions, while residues L28 and L31 likely act as hydrophobic constrictors, thereby restricting the free movement of water. The binding of amantadine to residues I20, E21, V24 and Y25 effectively blocks ion transport. However, this proposed molecular model requires experimental validation. Our findings give a structural insight into the models of CSFV p7 as an ion channel and provide a molecular explanation for the inhibition effects of amantadine on CSFV p7-mediated ion channel conductance.

The ion channel TRPM8 is a direct target of the immunosuppressant rapamycin in primary sensory neurons.

The mechanistic target of rapamycin (mTOR) signalling pathway is a key regulator of cell growth and metabolism. Its deregulation is implicated in several diseases. The macrolide rapamycin, a specific inhibitor of mTOR, has immunosuppressive, anti-inflammatory and antiproliferative properties. Recently, we identified tacrolimus, another macrolide immunosuppressant, as a novel activator of TRPM8 ion channels, involved in cold temperature sensing, thermoregulation, tearing and cold pain. We hypothesized that rapamycin may also have agonist activity on TRPM8 channels. Using calcium imaging and electrophysiology in transfected HEK293 cells and wildtype or Trpm8 KO mouse DRG neurons, we characterized rapamycin's effects on TRPM8 channels. We also examined the effects of rapamycin on tearing in mice. Micromolar concentrations of rapamycin activated rat and mouse TRPM8 channels directly and potentiated cold-evoked responses, effects also observed in human TRPM8 channels. In cultured mouse DRG neurons, rapamycin increased intracellular calcium levels almost exclusively in cold-sensitive neurons. Responses were markedly decreased in Trpm8 KO mice or by TRPM8 channel antagonists. Cutaneous cold thermoreceptor endings were also activated by rapamycin. Topical application of rapamycin to the eye surface evokes tearing in mice by a TRPM8-dependent mechanism. These results identify TRPM8 cationic channels in sensory neurons as novel molecular targets of the immunosuppressant rapamycin. These findings may help explain some of its therapeutic effects after topical application to the skin and the eye surface. Moreover, rapamycin could be used as an experimental tool in the clinic to explore cold thermoreceptors.

Identification of ubiquitin markers for survival and prognosis of ovarian cancer

Ovarian cancer (OC) is one of the most common malignancies and a leading cause of death among women worldwide. The ubiquitin pathway plays an important role in OC development. Using the single nucleotide polymorphism data obtained using the prevalence and dominance strategies, four ubiquitin marker genes were identified according to their expression levels: BARD1, BRCA2, FANCA, and BRCA1. Based on these four genes, a consensus clustering of OC expression data was performed. The significant differences in the survival analysis, ESTIMATE, and CIBERSORT results among the clusters indicated the pivotal role of these four genes in OC development. Of the ubiquitin-representative genes in each cluster, two ubiquitin genes, TOP2A and MYLIP, were identified in the survival risk model after univariate survival, Least Absolute Shrinkage and Selection Operator regression, and multivariate survival analyses. The reliability and robustness of both the training and validation data were confirmed by comparing the significant survival difference between high- and low-risk patients. We further explored the association between our risk model and clinical outcomes as well as predicted potentially interacting drugs. The co-expression network showed clear interactions among the four marker genes and two model genes and between high- and low-risk differentially expressed genes. Significantly enriched genes were found in pathways associated with ion channels, channel activity, and neuroactive ligand–receptor interactions. Therefore, suggesting the involvement of ubiquitin genes in the survival and development of OC through neurohumoral regulation. Our results will provide valuable reference or supplementary information for studies investigating OC diagnosis and therapies.