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Autism spectrum disorder (ASD) is a set of complex neurodevelopmental diseases that include impaired social interaction, delayed and disordered language, repetitive or stereotypic behavior, restricted range of interests, and altered sensory processing. The underlying causes of the core symptoms remain unclear, as are the factors that trigger their onset. Given the complexity and heterogeneity of the clinical phenotypes, a constellation of genetic, epigenetic, environmental, and immunological factors may be involved. The lack of appropriate biomarkers for the evaluation of neurodevelopmental disorders makes it difficult to assess the contribution of early alterations in neurochemical processes and neuroanatomical and neurodevelopmental factors to ASD. Abnormalities in the cholinergic system in various regions of the brain and cerebellum are observed in ASD, and recently altered cholesterol metabolism has been implicated at the initial stages of the disease. Given the multiple effects of the neutral lipid cholesterol on the paradigm rapid ligand-gated ion channel, the nicotinic acetylcholine receptor, we explore in this review the possibility that the dysregulation of nicotinic receptor-cholesterol crosstalk plays a role in some of the neurological alterations observed in ASD. [ABSTRACT FROM AUTHOR]

Bee venom (BV) is applied in different traditional medicinal therapies and is used worldwide to prevent and treat many acute and chronic diseases. Epilepsy has various neurological effects, e.g., epileptogenic insults; thus, it is considered a life-threatening condition. Seizures and their effects add to the burden of epilepsy because they can have health effects including residual disability and even premature mortality. The use of antiinflammatory drugs to treat epilepsy is controversial; therefore, the alternative nonchemical apitherapy benefits of BV were evaluated in the present study by assessing neuroinflammatory changes in a pilocarpine-induced epilepticus model. Levels of electrolytes, neurotransmitters, and mRNA expression for some gate channels were determined. Moreover, ELISA assays were conducted to detect pro- and anti-inflammatory cytokines, whereas RT-PCR was performed to assess mRNA expression of Foxp3 and CTLA-4. BV ameliorated the interruption in electrolytes and ions through voltage- and ligand-gated ion channels, and it limited neuronal excitability via rapid repolarization of action potentials. In addition, BV inhibited the high expression of proinflammatory cytokines. Acupuncture with BV was effective in preventing some of the deleterious consequences of epileptogenesis associated with high levels of glutamate and DOPA in the hippocampus. BV ameliorates changes in the expression of voltage-gated channels, rebalances blood electrolytes and neurotransmitters, and modulates the levels of pro- and anti-inflammatory cytokines. Thus, BV could reduce the progression of epileptogenesis as a cotherapy with other antiepileptic drugs. [ABSTRACT FROM AUTHOR]

Ion channels are transmembrane proteins that allow ions to flow across the cell membrane. They are characterized by selectivity. Physiological processes include excitation-contraction coupling, synaptic transmission, hormone secretion, and sensory transduction. Ion channels can be classified according to the presence or absence of gates; open and gated channels. Members of gated channels are; voltage-gated, ligand-gated, and other gating mechanisms. Ion channels that open following a change in the membrane voltage potential are known as voltage-gated ion channels. Ligand-gated ion channels allow ions to flow across the pore in response to the binding of an external chemical messenger (ligand). They are divided into four families: cys-loop receptors, ionotropic glutamate receptors, ATP-gated P2X receptors, and ligand-gated Ca 2+ channels. Other gating includes activation/inactivation by second messengers from within of the cell membrane. They include; transient receptor potential, cyclic nucleotide-gated channels, ATP sensitive K+ channels, calcium-activated K+ channels, mechanosensitive ion channels, acid-sensing ion channels, and cystic fibrosis transmembrane conductance regulator Cl - channels. This review aims to show the physiological bases of ion channel functions. That is important in understanding the pathophysiology, and treatment of channelopathies. [ABSTRACT FROM AUTHOR]

Ionotropic glutamate receptors (iGluRs) are tetrameric ligand-gated ion channels that play a crucial role in excitatory synaptic transmission in the central nervous system. Each subunit contributes with three helical transmembrane segments (M1, M3, and M4) and a pore loop (M2) to form the channel pore. Recent studies suggest that the architecture of all eukaryotic iGluRs derives from a common prokaryotic ancestral receptor that lacks M4 and consists only of transmembrane segments M1 and M3. Although significant contribution has emerged in the last years, the role of this additionally evolved transmembrane segment in iGluR assembly and function remains unclear. Here, we have investigated how deletions and mutations of M4 in members of the NMDA receptor (NMDAR) subfamily, the conventional heteromeric GluN1/GluN2 and glycine-gated GluN1/GluN3 NMDARs, affect expression and function in Xenopus oocytes. We show that deletion of M4 in the GluN1, GluN2A, or GluN3A subunit, despite retained receptor assembly and cell surface expression, results in nonfunctional membrane receptors. Coexpression of the corresponding M4 as an isolated peptide in M4-deleted receptors rescued receptor function of GluN1/GluN2A NMDARs without altering the apparent affinity of glutamate or glycine. Electrophysiological analyses of agonist-induced receptor function and its modulation by the neurosteroid pregnenolone sulfate (PS) at mutations of the GluN1-M4/GluN2/3-transmembrane interfaces indicate a crucial role of position M813 in M4 of GluN1 for functional coupling to the core receptor and the negative modulatory effects of PS. Substitution of residues and insertion of interhelical disulfide bridges confirmed interhelical interactions of positions in M4 of GluN1 with residues of transmembrane segments of neighboring subunits. Our results show that although M4s in NMDARs are not important for receptor assembly and surface expression, the residues at the subunit interface are substantially involved in M4 recognition of the core receptor and regulation of PS efficacy. Because mutations in the M4 of GluN1 specifically resulted in loss of PS-induced inhibition of GluN1/GluN2A and GluN1/GluN3A NMDAR currents, our results point to distinct roles of M4s in NMDAR modulation and highlight the importance of the evolutionarily newly evolved M4 for selective in vivo modulation of glutamate- and glycine-activated NMDARs by steroids. [ABSTRACT FROM AUTHOR]

Pentameric ligand-gated ion channels undergo subtle conformational cycling to control electrochemical signal transduction in many kingdoms of life. Several crystal structures have now been reported in this family, but the functional relevance of such models remains unclear. Here, we used small-angle neutron scattering (SANS) to probe ambient solution-phase properties of the pHgated bacterial ion channel GLIC under resting and activating conditions. Data collection was optimized by inline paused-flow size-exclusion chromatography, and exchanging into deuterated detergent to hide the micelle contribution. Resting-state GLIC was the best-fit crystal structure to SANS curves, with no evidence for divergent mechanisms. Moreover, enhanced-sampling moleculardynamics simulations enabled differential modeling in resting versus activating conditions, with the latter corresponding to an intermediate ensemble of both the extracellular and transmembrane domains. This work demonstrates state-dependent changes in a pentameric ion channel by SANS, an increasingly accessible method for macromolecular characterization with the coming generation of neutron sources. [ABSTRACT FROM AUTHOR]

Background and Purpose: The α4β2 nicotinic ACh receptor (nAChR), a subtype of the ligand‐gated ion channel, is abundantly expressed in the brain and is implicated in several neurological disorders. The endocytosis of nAChRs plays important roles in the pathogenesis of neurological diseases, but the underlying molecular mechanisms remain poorly understood. Experimental Approach Loss‐of‐function approaches and mutants of α4β2 nAChRs that display different endocytic properties were used to identify the cellular components and processes responsible for endocytosis. The signalling cascade that leads to endocytosis was deduced via protein interactions in predicted cellular components. The endocytosis of α4β2 nAChRs was determined and crosschecked using an ELISA and radioligand assay. Key Results: Endocytosis of α4β2 nAChRs occurred through clathrin‐mediated endocytosis in a dynamin‐dependent manner. 14‐3‐3η‐dependent Src‐mediated phosphorylation of the nAChR α4 subunit at Y575 was required for nAChR endocytosis, and this occurred with the assistance of β‐arrestin1 and GPCR kinase 2 (GRK2) without the need for kinase activity. Endocytosis triggered the mouse double minute 2 homologue‐mediated ubiquitination and subsequent down‐regulation of α4β2 nAChRs. Conclusions and Implications: α4β2 nAChR, an ionophore receptor, employs the metabotropic signalling pathway required for endocytosis, which leads to ubiquitination and down‐regulation. Further, GRK2 and β‐arrestin1, usually associated with GPCR signalling, are involved in the endocytosis of α4β2 nAChRs via different mechanisms. Considering the functional and pathological implications of nAChR endocytosis, results obtained in this study are crucial for the progression of basic research and clinical investigations. [ABSTRACT FROM AUTHOR]

Manfred Göthert, who had served Naunyn-Schmiedeberg's Arch Pharmacol as Managing Editor from 1998 to 2005, deceased in June 2019. His scientific oeuvre encompasses more than 20 types of presynaptic receptors, mostly on serotoninergic and noradrenergic neurones. He was the first to identify presynaptic receptors for somatostatin and ACTH and described many presynaptic receptors, known from animal preparations, also in human tissue. In particular, he elucidated the pharmacology of presynaptic 5-HT receptors. A second field of interest included ligand-gated and voltage-dependent channels. The negative allosteric effect of anesthetics at peripheral nACh receptors is relevant for the peripheral clinical effects of these drugs and modified the Meyer-Overton hypothesis. The negative allosteric effect of ethanol at NMDA receptors in human brain tissue occurred at concentrations found in the range of clinical ethanol intoxication. Moreover, the inhibitory effect of gabapentinoids on P/Q Ca2+ channels and the subsequent decrease in AMPA-induced noradrenaline release may contribute to their clinical effect. Another ligand-gated ion channel, the 5-HT3 receptor, attracted the interest of Manfred Göthert from the whole animal via isolated preparations down to the cellular level. He contributed to that molecular study in which 5-HT3 receptor subtypes were disclosed. Finally, he found altered pharmacological properties of 5-HT receptor variants like the Arg219Leu 5-HT1A receptor (which was also shown to be associated with major depression) and the Phe124Cys 5-HT1B receptor (which may be related to sumatriptan-induced vasospasm). Manfred Göthert was a brilliant scientist and his papers have a major impact on today's pharmacology. [ABSTRACT FROM AUTHOR]

Background: γ-Aminobutyric acid sub-type A receptors (GABAARs) are the most prominent inhibitory neurotransmitter receptors in the CNS. They are a family of ligand-gated ion channel with significant physiological and therapeutic implications. Main body: GABAARs are heteropentamers formed from a selection of 19 subunits: six α (alpha1-6), three β (beta1-3), three γ (gamma1-3), three ρ (rho1-3), and one each of the δ (delta), ε (epsilon), π (pi), and θ (theta) which result in the production of a considerable number of receptor isoforms. Each isoform exhibits distinct pharmacological and physiological properties. However, the majority of GABAARs are composed of two α subunits, two β subunits, and one γ subunit arranged as γ2β2α1β2α1 counterclockwise around the center. The mature receptor has a central chloride ion channel gated by GABA neurotransmitter and modulated by a variety of different drugs. Changes in GABA synthesis or release may have a significant effect on normal brain function. Furthermore, The molecular interactions and pharmacological effects caused by drugs are extremely complex. This is due to the structural heterogeneity of the receptors, and the existence of multiple allosteric binding sites as well as a wide range of ligands that can bind to them. Notably, dysfunction of the GABAergic system contributes to the development of several diseases. Therefore, understanding the relationship between GABAA receptor deficits and CNS disorders thus has a significant impact on the discovery of disease pathogenesis and drug development. Conclusion: To date, few reviews have discussed GABAA receptors in detail. Accordingly, this review aims to summarize the current understanding of the structural, physiological, and pharmacological properties of GABAARs, as well as shedding light on the most common associated disorders. [ABSTRACT FROM AUTHOR]

7-Ketocholesterol (7-KC), for example, is one of the major oxysterols present in human atherosclerotic lesions (Brown & Jessup, 1999), and especially enriched in cholesterol-filled macrophages where it impairs cholesterol efflux, driving the foam cell phenotype (Gelissen et al., 1996). This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. 2-Hydroxypropyl- -cyclodextrin reduces retinal cholesterol in wild-type and Cyp27a1 -/- Cyp46a1 -/- mice with deficiency in the oxysterol production. Cytoplasmic oxysterol-binding proteins: Sterol sensors or transporters?. [Extracted from the article]

The brain is the most cholesterol rich organ in the body containing about 25% of the body's free cholesterol. Cholesterol cannot pass the blood–brain barrier and be imported or exported; instead, it is synthesised in situ and metabolised to oxysterols, oxidised forms of cholesterol, which can pass the blood–brain barrier. 24S‐Hydroxycholesterol is the dominant oxysterol in the brain after parturition, but during development, a myriad of other oxysterols are produced, which persist as minor oxysterols after birth. During both development and in later life, sterols and oxysterols interact with a variety of different receptors, including nuclear receptors, membrane bound GPCRs, the oxysterol/sterol sensing proteins INSIG and SCAP, and the ligand‐gated ion channel NMDA receptors found in nerve cells. In this review, we summarise the different oxysterols and sterols found in the CNS whose biological activity is transmitted via these different classes of protein receptors. LINKED ARTICLES: This article is part of a themed issue on Oxysterols, Lifelong Health and Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.16/issuetoc [ABSTRACT FROM AUTHOR]

Ligand-gated ion channels are integral membrane proteins that activate through a change in conformation upon transmitter binding and were identified as key players of brain function. GABA A receptors are major inhibitory ligand-gated ion channels of this protein family. They are the target of many therapeutic compounds widely used in the clinic and continue to attract the attention of academic and pharmaceutical laboratories. Advances in the knowledge of the structure of GABA A receptors at the molecular level with unprecedented resolution enabled the determination of the binding sites of many allosteric modulators revealing the nature of their interactions with the receptors. Herein, we review the latest findings on allosteric modulation of GABA A receptors and their relevance to drug discovery. • Allosteric Modulators at the GABA A receptors. • Importance for therapeutic treatment. • Associated proteins. [ABSTRACT FROM AUTHOR]

Pentameric ligand-gated ion channels (pLGICs) are crucial mediators of electrochemical signal transduction in various organisms from bacteria to humans. Lipids play an important role in regulating pLGIC function, yet the structural bases for specific pLGIC-lipid interactions remain poorly understood. The bacterial channel ELIC recapitulates several properties of eukaryotic pLGICs, including activation by the neurotransmitter GABA and binding and modulation by lipids, offering a simplified model system for structure-function relationship studies. In this study, functional effects of noncanonical amino acid substitution of a potential lipid-interacting residue (W206) at the top of the M1-helix, combined with detergent interactions observed in recent X-ray structures, are consistent with this region being the location of a lipid-binding site on the outward face of the ELIC transmembrane domain. Coarse-grained and atomistic molecular dynamics simulations revealed preferential binding of lipids containing a positive charge, particularly involving interactions with residue W206, consistent with cation-π binding. Polar contacts from other regions of the protein, particularly M3 residue Q264, further support lipid binding via headgroup ester linkages. Aromatic residues were identified at analogous sites in a handful of eukaryotic family members, including the human GABAA receptor ε subunit, suggesting conservation of relevant interactions in other evolutionary branches. Further mutagenesis experiments indicated that mutations at this site in ε-containing GABAA receptors can change the apparent affinity of the agonist response to GABA, suggesting a potential role of this site in channel gating. In conclusion, this work details type-specific lipid interactions, which adds to our growing understanding of how lipids modulate pLGICs. [ABSTRACT FROM AUTHOR]

BACKGROUND Cockroaches are serious urban pests that can transfer disease‐causing microorganisms as well as trigger allergic reactions and asthma. They are commonly managed by pesticides that act on cys‐loop ligand‐gated ion channels (cysLGIC). To provide further information that will enhance our understanding of how insecticides act on their molecular targets in cockroaches, we used genome and reverse transcriptase polymerase chain reaction (RT‐PCR) data to characterize the cysLGIC gene superfamilies from Blattella germanica and Periplaneta americana. RESULTS: The B. germanica and P. americana cysLGIC superfamilies consist of 30 and 32 subunit‐encoding genes, respectively, which are the largest insect cysLGIC superfamilies characterized to date. As with other insects, the cockroaches possess ion channels predicted to be gated by acetylcholine, γ‐aminobutyric acid, glutamate and histamine, as well as orthologues of the drosophila pH‐sensitive chloride channel (pHCl), CG8916 and CG12344. The large cysLGIC superfamilies of cockroaches are a result of an expanded number of divergent nicotinic acetylcholine receptor subunits, with B. germanica and P. americana, respectively, possessing eight and ten subunit genes. Diversity of the cockroach cysLGICs is also broadened by alternative splicing and RNA A‐to‐I editing. Unusually, both cockroach species possess a second glutamate‐gated chloride channel as well as another CG8916 subunit. CONCLUSION: These findings on B. germanica and P. americana enhance our understanding of the evolution of the insect cysLGIC superfamily and provide a useful basis for the study of their function, the detection and management of insecticide resistance, and for the development of improved pesticides with greater specificity towards these major pests. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Vertebrate and invertebrate ligand‐gated ion channels (LGICs) exhibit significant structural homology and often share ligands. As a result, ligands with activity against one class can be brought to bear against another, including for development as insecticides. Receptor selectivity, metabolism and distribution must then be optimized using chemical synthesis. Here we review natural products (NPs) that ligate and inhibit the Cys‐loop family of LGICs, which benefit from the unique physicochemical properties of natural product space but often present a high synthetic burden. Recent advances in chemical synthesis, however, have opened practical entries into these complex structures, several of which are highlighted. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Insect Rdl GABA receptor is an important insecticide target. To design a novel insecticide, studies on the structures of homologous pentameric ligand‐gated ion channels provide information about important amino acids that are necessary for the function of insect Rdl GABA receptors. RESULTS: L9'A, T12'A, T13'A, T13'S, M15'S, and M15′N mutations in the Drosophila Rdl GABA receptor subunit caused the protein to spontaneously adopt the open state conformation. In contrast, the S16'A, S16′T, S17'A, and S17′H mutant homomers showed the same levels of agonist and antagonist sensitivity as the wild‐type receptor. The G336M mutation in the Drosophila Rdl GABA receptor abolished the agonist activities of ivermectin and milbemectin, but the F339M mutation did not. Additionally, the F339M mutation caused spontaneous opening of the receptor. In the Drosophila Rdl model, the hydrophobic girdle plays an important role in stabilization of the closed state. Mutations which decrease hydrophobic interactions resulted in spontaneous opening, supporting the importance of the hydrophobic girdle for keeping the channel closed. Through a mutational study of transmembrane 3 (TM3) cytoplasmic domain and Rdl GABA receptor modeling, hydrophobic interactions between TM3 and TM4 and intersubunit interaction were demonstrated to be important for channel gating. Alternatively, the intrasubunit interaction between TM2 and TM3 domains were less important for channel gating in case of Drosophila Rdl GABA receptor. CONCLUSION: This study demonstrates important amino acids critical to the function of the Drosophila Rdl GABA receptor based on the mutational studies and Drosophila Rdl GABA receptor modeling approach. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Pentameric ligand-gated ion channels (pLGICs) activated by the inhibitory neurotransmitter γ-aminobutyric acid (GABA) are expressed widely in both vertebrate and invertebrate species. One of the best characterised insect GABA-gated chloride channels is RDL, an abbreviation of 'resistance to dieldrin', that was originally identified by genetic screening in Drosophila melanogaster. Here we have cloned the analogous gene from the bumblebee Bombus terrestris audax (BtRDL) and examined its pharmacological properties by functional expression in Xenopus oocytes. Somewhat unexpectedly, the sensitivity of BtRDL to GABA, as measured by its apparent affinity (EC50), was influenced by heterologous expression conditions. This phenomenon was observed in response to alterations in the amount of cRNA injected; the length of time that oocytes were incubated before functional analysis; and by the presence or absence of a 3' untranslated region. In contrast, similar changes in expression conditions were not associated with changes in apparent affinity with RDL cloned from D. melanogaster (DmRDL). Changes in apparent affinity with BtRDL were also observed following co-expression of a chaperone protein (NACHO). Similar changes in apparent affinity were observed with an allosteric agonist (propofol) and a non-competitive antagonist (picrotoxinin), indicating that expression-depended changes are not restricted to the orthosteric agonist binding site. Interestingly, instances of expression-dependent changes in apparent affinity have been reported previously for vertebrate glycine receptors, which are also members of the pLGIC super-family. Our observations with BtRDL are consistent with previous data obtained with vertebrate glycine receptors and indicates that agonist and antagonist apparent affinity can be influenced by the level of functional expression in a variety of pLGICs. [ABSTRACT FROM AUTHOR]

Recurrent seizures are characteristic to epilepsy, which often arise due to increased electrical activity. Ligand-gated ion channels are considered as key factors in epilepsy as they regulate and maintain neuronal membrane potential via regulating ion transportation. Therefore, this study aims to identify ion channel-related single nucleotide variations that are considered as risk factors in epilepsy and determine their potential effects on pathogenicity, protein stability and structure using in silico methods. For this purpose, ion channel-related mutations linked with epilepsy were retrieved from ClinVar. Pathogenicity scores and protein stability were predicted using FATHMM-XF and MUpro, respectively. Structural alterations were determined via HOPE server. We identified 17 epilepsy-related missense mutations, 11 of which were in ion channel-related genes. Nonsynonymous substitutions of p.E177A, p.D219N, p.A322D, p.R577Q, p.E282K, p.V831M and p.R1072C were determined as pathogenic, while all mutations resulted in varying degrees of decrease in overall protein stability. Furthermore, all variants were annotated with risk for disease and introduction of distinct side chains caused differences in size, charge and hydrophobicity, as well as contact with other proteins and ligands. In conclusion, mutations in ion channel-related genes were previously identified in several genetic association studies while their functional annotations were not addressed. The results of this study provide a functional explanation to the pathogenic effects of ion channelrelated gene mutations that are considered as risk factors in epilepsy. [ABSTRACT FROM AUTHOR]

In the tumor microenvironment, inflammation and necrosis cause the accumulations of ATP extracellularly, and high concentrations of ATP can activate P2X7 receptors (P2X7R), which leads to the influx of Na+, K+, or Ca2+ into cells and trigger the downstream signaling pathways. P2X7R is a relatively unique ligand‐gated ion channel, which is over‐expressed in most tumor cells. The activated P2X7R facilitates the tumor growth, invasion, and metastasis. Inhibition of the P2X7R activation can be applied as a potential anti‐tumor therapy strategy. There are currently no anti‐tumor agents against P2X7R, though several P2X7R antagonists for indications such as anti‐inflammatory and anti‐depression were reported. In this study, we combined homology modeling (HM), virtual screening, and EB intake assay to characterize the structural features of P2X7R and identify several novel antagonists, which were chemically different from any other known P2X7R antagonists. The identified antagonists could effectively prevent the pore opening of P2X7R with IC50 values ranging from 29.14 to 35.34 μM. HM model showed the area between ATP‐binding pocket, and allosteric sides were hydrophobic and suitable for small molecule interaction. Molecular docking indicated a universal binding mode, of which residues R294 and K311 were used as hydrogen bond donors to participate in antagonist interactions. The binding mode can potentially be utilized for inhibitor optimization for increased affinity, and the identified antagonists can be further tested for anti‐cancer activity or may serve as chemical agents to study P2X7R related functions. [ABSTRACT FROM AUTHOR]

Despite the fact that transmembrane proteins represent the main therapeutic targets for decades, complete and in‐depth knowledge about their biochemical and pharmacological profiling is not fully available. In this regard, target‐tailored small‐molecule fluorescent ligands are a viable approach to fill in the missing pieces of the puzzle. Such tools, coupled with the ability of high‐precision optical techniques to image with an unprecedented resolution at a single‐molecule level, helped unraveling many of the conundrums related to plasma proteins' life‐cycle and druggability. Herein, we review the recent progress made during the last two decades in fluorescent ligand design and potential applications in fluorescence microscopy of voltage‐gated ion channels, ligand‐gated ion channels and G‐coupled protein receptors. [ABSTRACT FROM AUTHOR]

Although it has long been proposed that membrane proteins may contain tightly bound lipids, their identity, the structure of their binding sites, and their functional and structural relevance have remained elusive. To some extent, this is because tightly bound lipids are often located at the periphery of proteins, where the quality of density maps is usually poorer, and because they may be outcompeted by detergent molecules used during standard purification procedures. As a step toward characterizing natively bound lipids in the superfamily of pentameric ligand-gated ion channels (pLGICs), we applied singleparticle cryogenic electron microscopy to fragments of native membrane obtained in the complete absence of detergent-solubilization steps. Because of the heterogeneous lipid composition of membranes in the secretory pathway of eukaryotic cells, we chose to study a bacterial pLGIC (ELIC) expressed in Escherichia coli's inner membrane. We obtained a three-dimensional reconstruction of unliganded ELIC (2.5-Å resolution) that shows clear evidence for two types of tightly bound lipid at the protein-bulk-membrane interface. One of them was consistent with a "regular" diacylated phospholipid, in the cytoplasmic leaflet, whereas the other one was consistent with the tetra-acylated structure of cardiolipin, in the periplasmic leaflet. Upon reconstitution in E. coli polar-lipid bilayers, ELIC retained the functional properties characteristic of members of this superfamily, and thus, the fitted atomic model is expected to represent the (long-debated) unliganded-closed, "resting" conformation of this ion channel. Notably, the addition of cardiolipin to phosphatidylcholine membranes restored the ion-channel activity that is largely lost in phosphatidylcholine-only bilayers. [ABSTRACT FROM AUTHOR]

Thiamethoxam is a neonicotinoid group of insecticide which are selective agonists of the insect nicotinic acetylcholine receptor (nAChR), a pentameric cys-loop ligand-gated ion channel located in the central nervous system of insects. They provide farmers with invaluable, highly effective tools against some of the world's most destructive crop pests. Black legume aphids, Aphis craccivora is one of the devastating polyphagous pests in agroecosystem and to manage their population, farmers are still relying on application of synthetic insecticides like Thiamethoxam. To evaluate the risk of resistance development, selection of A. craccivora was done to characterize Thiamethoxam resistance along with evaluation of developmental and reproductive fitness cost of the resistance. About 86.19 folds of resistance were developed after selecting for 24 generations. In the first twelve generations steady development of resistance was noticed followed by development become stiffer till 16th generation and more or less stable till 24th generations. Relative fitness of the selected resistant strain of aphids was decreased with longer nymphal duration and adult longevity. The mean nymphal duration was increased from 4.35±1.02 days (in F0) to 7.9±0.57 days (in F24). The fecundity rate was significantly less in resistant population (16.0±5.34) as compared to the susceptible strain (54.71±7.63) whereas, oviposition periods were significantly longer (12.49±1.44 days) in resistant population as compare to susceptible strain (9.50±1.22 days). [ABSTRACT FROM AUTHOR]

GABA A receptors are pentameric ligand-gated ion channels that mediate most fast neuronal inhibition in the brain. In addition to their important physiological roles, they are noteworthy in their rich pharmacology; prominent drugs used for anxiety, insomnia, and general anesthesia act through positive modulation of GABA A receptors. Direct structural information for how these drugs work was absent until recently. Efforts in structural biology over the past few years have revealed how important drug classes and natural products interact with the GABA A receptor, providing a foundation for studies in dynamics and structure-guided drug design. Here, we review recent developments in GABA A receptor structural pharmacology, focusing on subunit assemblies of the receptor found at synapses. GABA A receptors are ion channels important in brain function and are the target of chemically diverse and clinically important drugs for insomnia, epilepsy, and anesthesia. Recent structures of GABA A receptors have revealed detailed interactions of the neurotransmitter GABA, benzodiazepines, general anesthetics, and antagonists. Intravenous anesthetics bind in both common and distinctive membrane sites. Electrophysiological and molecular dynamics studies build off the static structures, to probe mechanisms of potentiation and inhibition by chemically diverse compounds. [ABSTRACT FROM AUTHOR]

Background: Binge drinking can increase an individual's risk of developing alcohol use disorder (AUD). Ethanol targets multiple neurotransmitter systems; however, not much is known about its effects on the cholinergic system. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels, the heteromeric α4β2 nAChR being a commonly expressed subtype. Desformylflustrabromine (dFBr), a positive allosteric modulator (PAM), increases the efficacy of α4β2 nAChR in vitro and has previously been shown to have translational potential. In this study, we investigated whether dFBr modulates the hypnotic response to ethanol.Methods: Ethanol-induced loss of righting reflex (LORR) duration was measured in the presence and absence of dFBr. The β2 nAChR selective antagonist dihydro-β-erythroidine (DHβE) was used to study the involvement of the β2 subunit. Additionally, we used a crosslinking-based western blot assay to estimate changes in total versus intracellular α4 nAChR protein in thalamic tissue of rats treated with vehicle, dFBr, ethanol, or ethanol and dFBr. Lastly, using Xenopus oocyte two-electrode voltage clamp (TEVC) studies, we determined the effects of ethanol and dFBr on α4β2 nAChR.Results: Pretreatment with 6 mg/kg dFBr reduced ethanol-induced LORR duration as compared to rats treated with ethanol alone. LORR studies with DHβE suggest that dFBr reduced ethanol-induced LORR duration via the β2 nAChR subunit. Crosslinking-based western analyses revealed that ethanol caused early increases in total and presumably surface thalamic α4 nAChR subunit protein levels. This ethanol-induced α4 nAChR upregulation was significantly reduced in rats pretreated with 6 mg/kg dFBr. In TEVC studies, ethanol potentiated ACh-induced currents in α4β2 nAChR, while it slightly reduced dFBr potentiation of maximal ACh currents.Conclusions: Our results suggest that thalamic nAChRs containing the α4 subunit are rapidly upregulated by a single intoxicating dose of ethanol. Furthermore, dFBr, an α4β2 nAChR-selective PAM, significantly attenuates the hypnotic response to ethanol via actions on β2 nAChR. Overall, these results indicate that dFBr represents an option to reverse ethanol intoxication. [ABSTRACT FROM AUTHOR]

Ligand-gated ion channels (LGIC) are membranous proteins that allow ionic flow across plasma membrane upon ligand binding. The channels are implicated in many physiological and pathological processes. Understanding the functionality of LGIC leads to a better understanding of normal physiology, as well as diseases. One of many approaches to study LGIC is through the development of new ligands. Natural products provide a rich source of such ligands. Spider venom includes biologically active compounds with different mechanisms of action. Some components target LGIC. The current review summarizes toxins of spider origin that act on glutamate receptors, nicotinic acetylcholine receptors (nAChRs), and purinergic receptors. [ABSTRACT FROM AUTHOR]

The P2X4 receptor is a trimeric ligand-gated ion channel activated by adenosine 5′-triphosphate (ATP). P2X4 is present in immune cells with emerging roles in inflammation and immunity, and related disorders. This review aims to provide an overview of the methods commonly used to study P2X4 in immune cells, focusing on those methods used to assess P2RX4 gene expression, the presence of the P2X4 protein, and P2X4 ion channel activity in these cells from humans, dogs, mice and rats. P2RX4 gene expression in immune cells is commonly assessed using semi-quantitative and quantitative reverse-transcriptase-PCR. The presence of P2X4 protein in immune cells is mainly assessed using anti-P2X4 polyclonal antibodies with immunoblotting or immunochemistry, but the use of these antibodies, as well as monoclonal antibodies and nanobodies to detect P2X4 with flow cytometry is increasing. Notably, use of an anti-P2X4 monoclonal antibody and flow cytometry has revealed that P2X4 is present on immune cells with a rank order of expression in eosinophils, then neutrophils and monocytes, then basophils and B cells, and finally T cells. P2X4 ion channel activity has been assessed mainly by Ca2+ flux assays using the cell permeable Ca2+-sensitive dyes Fura-2 and Fluo-4 with fluorescence microscopy, spectrophotometry, or flow cytometry. However, other methods including electrophysiology, and fluorescence assays measuring Na+ flux (using sodium green tetra-acetate) and dye uptake (using YO-PRO-12+) have been applied. Collectively, these methods have demonstrated the presence of functional P2X4 in monocytes and macrophages, microglia, eosinophils, mast cells and CD4+ T cells, with other evidence suggestive of functional P2X4 in dendritic cells, neutrophils, B cells and CD8+ T cells. [ABSTRACT FROM AUTHOR]

Cys-loop ligand-gated channels mediate neurotransmission in insects and are receptors for many insecticides. Some insecticides acting on cysLGIC also have lethal effects on non-targeting organisms, but the mechanism of this negative effect is unclear due to information absence. The identification and analysis of cysLGIC family in Pardosa pseudoannulata , a pond wolf spider, can deepen the understanding of insecticides for natural enemy safety. Thirty-four cysLGIC genes were identified in P. pseudoannulata genome, including nicotinic acetylcholine receptors, γ-aminobutyric acid gated chloride channels, glutamate-gated chloride channels, histamine-gated chloride channels, and pH-sensitive chloride channels. The expansion of GABACls and HisCls accounts for the large number of cysLGICs in P. pseudoannulata, and the alternative splicing events in nAChR and RDL subunits enriched the diversity of the superfamily. Most cysLGIC genes show the highest expression in brain and lowest expression in the early-egg sac stage. Variable residues (R81, V83, R135, N137, F190, and W197) in P. pseudoannulata nAChR β subunits and critical differences in α6 subunit TM4 region compared with insects would apply for the insensitivity to neonicotinoids and spinosyn. In contrast, avermectin and dieldrin may be lethal to P. pseudoannulata due to the similar drugs binding sites in GluCls compared with insects. These findings will provide a valuable clue for natural enemy protection and environmentally friendly insecticide development. [Display omitted] • 34 cysLGIC genes were detected in P. pseudoannulata genome, including nAChRs, GABACls, GluCls, HisCls and pHCls. • Few numbers of nAChR and GABA subunits in P. pseudoannulata have alternative splicing events. • Most of the cysLGIC genes show the highest expression in P. pseudoannulata central neuron system. • The variable residues in nAChR α6 and β1 subunits could account for resistance P. pseudoannulata to the two insecticides. [ABSTRACT FROM AUTHOR]

A recent paper by Carrillo and colleagues demonstrates that GluD proteins form bona fide ligand-gated ion channels when their intrinsic flexibility is constrained by interactions with protein partners. Therefore, Delta receptors resemble all other members of the ionotropic glutamate receptor family not only by sequence and structural homology, but also by functional dynamics. [ABSTRACT FROM AUTHOR]

The article presents a study that explores the molecular mechanisms of metabotropic GABAB receptor function. It mentions that metabotropic gamma-aminobutyric acid G protein–coupled receptors (GABAB), represent one of the two main types of inhibitory neurotransmitter receptors in the brain. It discusses the comprehensive insights into the activation of the GABAB receptor.

Ionotropic glutamate receptors (iGluRs) are a major class of ligand‐gated ion channels that are widespread in the living kingdom. Their critical role in excitatory neurotransmission and brain function of arthropods and vertebrates has made them a compelling subject of interest for neurophysiologists and pharmacologists. This is particularly true for NMDA receptor (NMDARs), a subclass of iGluRs that act as central drivers of synaptic plasticity in the CNS. How and when the unique properties of NMDARs arose during evolution, and how they relate to the evolution of the nervous system, remain open questions. Recent years have witnessed a boom in both genomic and structural data, such that it is now possible to analyse the evolution of iGluR genes on an unprecedented scale and within a solid molecular framework. In this review, combining insights from phylogeny, atomic structure and physiological and mechanistic data, we discuss how evolution of NMDAR motifs and sequences shaped their architecture and functionalities. We trace differences and commonalities between NMDARs and other iGluRs, emphasizing a few distinctive properties of the former regarding ligand binding and gating, permeation, allosteric modulation and intracellular signalling. Finally, we speculate on how specific molecular properties of iGuRs arose to supply new functions to the evolving structure of the nervous system, from early metazoan to present mammals. [ABSTRACT FROM AUTHOR]

Epileptic encephalopathy (EE) is a devastating pediatric disease that features medically resistant seizures, which can contribute to global developmental delays. Despite technological advancements in genetics, the neurobiological mechanisms of EEs are not fully understood, leaving few therapeutic options for affected patients. In this review, we introduce the most common EEs in pediatrics (i.e., Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome) and their molecular mechanisms that cause excitation/inhibition imbalances. We then discuss some of the essential molecules that are frequently dysregulated in EEs. Specifically, we explore voltage-gated ion channels, synaptic transmission-related proteins, and ligand-gated ion channels in association with the pathophysiology of Ohtahara syndrome, Dravet syndrome, and Lennox-Gastaut syndrome. Finally, we review currently available antiepileptic drugs used to treat seizures in patients with EEs. Since these patients often fail to achieve seizure relief even with the combination therapy, further extensive research efforts to explore the involved molecular mechanisms will be required to develop new drugs for patients with intractable epilepsy. [ABSTRACT FROM AUTHOR]

Peripheral inflammatory and neuropathic pain are closely related to the activation of purinergic receptor P2X ligand-gated ion channel 3 (P2X3) and transient receptor potential vanilloid 1 (TRPV1), but the interaction between P2X3 and TRPV1 in different types of pathological pain has rarely been reported. In this study, complete Freund's adjuvant (CFA)-induced inflammatory pain and spared nerve injury (SNI)-induced neuropathic pain models were established in adult rats. The interactions between P2X3 and TRPV1 in the dorsal root ganglion were observed by pharmacological, co-immunoprecipitation, immunofluorescence and whole-cell patch-clamp recording assays. TRPV1 was shown to promote the induction of spontaneous pain caused by P2X3 in the SNI model, but the induction of spontaneous pain behaviour by TRPV1 was not completely dependent on P2X3 in vivo. In both the CFA and SNI models, the activation of peripheral P2X3 enhanced the effect of TRPV1 on spontaneous pain, while the inhibition of peripheral TRPV1 reduced the induction of spontaneous pain by P2X3 in the CFA model. TRPV1 and P2X3 had inhibitory effects on each other in the inflammatory pain model. During neuropathic pain, P2X3 facilitated the function of TRPV1, while TRPV1 had an inhibitory effect on P2X3. These results suggest that the mutual effects of P2X3 and TRPV1 differ in cases of inflammatory and neuropathic pain in rats. [ABSTRACT FROM AUTHOR]

An accurate olfactory system for recognizing semiochemicals and environmental chemical signals plays crucial roles in survival and reproduction of insects. Among all olfaction-related proteins, olfactory receptors (ORs) contribute to the conversion of chemical stimuli to electric signals and thereby are vital in odorant recognition. Olfactory receptor co-receptor (Orco), one of the most conserved ORs, is extremely essential in recognizing odorants through forming a ligand-gated ion channel complex with conventional ligand-binding odorant receptors. We have previously identified aggregation pheromone in Protaetia brevitarsis (Coleoptera: Scarabaeidae), a native agricultural and horticultural pest in East-Asia. However, to our best knowledge, its olfaction recognition mechanisms are still veiled. To illustrate how P. brevitarsis recognize aggregation pheromone and host plants, in the present study we cloned and sequenced the full-length Orco gene from P. brevitarsis antennae (named PbreOrco) and found that PbreOrco is highly conserved and similar to Orcos from other Coleoptera insects. Our real-time quantitative PCR (qRT-PCR) results showed that PbreOrco is mainly expressed in antenna. We also demonstrated that silencing PbreOrco using RNA interference through injecting dsOrco fragment significantly inhibited PbreOrco expression in comparison with injecting control dsGFP and subsequently revealed using electroantennogram and behavioral bioassays that decreasing PbreOrco transcript abundance significantly impaired the responses of P. brevitarsis to intraspecific aggregation pheromone and prolonged the time of P. brevitarsis spending on food seeking. Overall, our results demonstrated that PbreOrco is crucial in mediating odorant perception in P. brevitarsis. [ABSTRACT FROM AUTHOR]

GABAA receptors (GABAARs) are pentameric ligand-gated ion channels distributed throughout the brain where they mediate synaptic and tonic inhibition. Following activation, these receptors undergo desensitization which involves entry into long-lived agonist-bound closed states. Although the kinetic effects of this state are recognised and its structural basis has been uncovered, the physiological impact of desensitization on inhibitory neurotransmission remains unknown. Here we describe an enduring form of long-term potentiation at inhibitory synapses that elevates synaptic current amplitude for 24 h following desensitization of GABAARs in response to agonist exposure or allosteric modulation. Using receptor mutants and allosteric modulators we demonstrate that desensitization of GABAARs facilitates their phosphorylation by PKC, which increases the number of receptors at inhibitory synapses. These observations provide a physiological relevance to the desensitized state of GABAARs, acting as a signal to regulate the efficacy of inhibitory synapses during prolonged periods of inhibitory neurotransmission. Following activation, GABAA receptors (GABAARs) undergo desensitization, the impact of which on inhibitory neurotransmission remains unknown. Here the authors describe an enduring form of long-term potentiation at inhibitory synapses that elevates synaptic current amplitude for 24 h following desensitization of GABAARs. [ABSTRACT FROM AUTHOR]

One of the most fundamental questions in the field of Cys-loop receptors (pentameric ligand-gated ion channels, pLGICs) is how the affinity for neurotransmitters and the conductive/nonconductive state of the transmembrane pore are correlated despite the ~60-Å distance between the corresponding domains. Proposed mechanisms differ, but they all converge into the idea that interactions between wild-type side chains across the extracellular-transmembranedomain (ECD-TMD) interface are crucial for this phenomenon. Indeed, the successful design of fully functional chimeras that combine intact ECD and TMD modules from different wild-type pLGICs has commonly been ascribed to the residual conservation of sequence that exists at the level of the interfacial loops even between evolutionarily distant parent channels. Here, using mutagenesis, patchclamp electrophysiology, and radiolabeled-ligand binding experiments, we studied the effect of eliminating this residual conservation of sequence on ion-channel function and cell-surface expression. From our results, we conclude that proper state interconversion ("gating") does not require conservation of sequence--or even physicochemical properties--across the ECD-TMD interface. Wild-type ECD and TMD side chains undoubtedly interact with their surroundings, but the interactions between them--straddling the interface--do not seem to be more important for gating than those occurring elsewhere in the protein. We propose that gating of pLGICs requires, instead, that the overall structure of the interfacial loops be conserved, and that their relative orientation and distance be the appropriate ones for changes in one side to result in changes in the other, in a phenomenon akin to the nonspecific "bumping" of closely apposed domains. [ABSTRACT FROM AUTHOR]

BACKGROUND: The cys-loop ligand-gated ion channels, including the glutamate-gated chloride channel (GluCl) and GABAgated chloride channel (Rdl) are important targets for drugs and pesticides. The macrocyclic lactone abamectin primarily targets GluCl and is commonly used to control the spider mite Tetranychus urticae, an economically important crop pest. However, abamectin resistance has been reported for multiple T. urticae populations worldwide, and in several cases was associated with the mutations G314D in GluCl1 and G326E in GluCl3. Recently, an additional I321T mutation in GluCl3 was identified in several abamectin resistant T. urticae field populations. Here, we aim to functionally validate this mutation and determine its phenotypic strength. RESULTS: The GluCl3 I321T mutation was introgressed into a T. urticae susceptible background by marker-assisted backcrossing, revealing contrasting results in phenotypic strength, ranging from almost none to 50-fold. Next, we used CRISPR-Cas9 to introduce I321T, G314D and G326E in the orthologous Drosophila GluCl. Genome modified flies expressing GluCl I321T were threefold less susceptible to abamectin, while CRISPRed GluCl G314D and G326E flies were lethal. Last, functional analysis in Xenopus oocytes revealed that the I321T mutation might reduce GluCl3 sensitivity to abamectin, but also suggested that all three T. urticae Rdls are affected by abamectin. CONCLUSION: Three different techniques were used to characterize the role of I321T in GluCl3 in abamectin resistance and, combining all results, our analysis suggests that the I321T mutation has a complex role in abamectin resistance. Given the reported subtle effect, additional synergistic factors in resistance warrant more investigation. [ABSTRACT FROM AUTHOR]

Transmitter signalling is the universal chemical language of any nervous system, but little is known about its early evolution. Here, we summarize data about the distribution and functions of neurotransmitter systems in basal metazoans as well as outline hypotheses of their origins. We explore the scenario that neurons arose from genetically different populations of secretory cells capable of volume chemical transmission and integration of behaviours without canonical synapses. The closest representation of this primordial organization is currently found in Placozoa, disk-like animals with the simplest known cell composition but complex behaviours. We propose that injury-related signallingwas the evolutionary predecessor for integrative functions of early transmitters such as nitric oxide, ATP, protons, glutamate and small peptides. By contrast, acetylcholine, dopamine, noradrenaline, octopamine, serotonin and histamine were recruited as canonical neurotransmitters relatively later in animal evolution, only in bilaterians. Ligand-gated ion channels often preceded the establishment of novel neurotransmitter systems. Moreover, lineage-specific diversification of neurotransmitter receptors occurred in parallel within Cnidaria and several bilaterian lineages, including acoels. In summary, ancestral diversification of secretory signal molecules provides unique chemical microenvironments for behaviour-driven innovations that pave the way to complex brain functions and elementary cognition. This article is part of the theme issue 'Basal cognition: multicellularity, neurons and the cognitive lens'. [ABSTRACT FROM AUTHOR]

NMDARs are ligand-gated ion channels that cause an influx of Na+ and Ca2+ into postsynaptic neurons. The resulting intracellular Ca2+ transient triggers synaptic plasticity. When prolonged, it may induce excitotoxicity, but it may also activate negative feedback to control the activity of NMDARs. Here, we report that a transient rise in intracellular Ca2+ (Ca2+ challenge) increases the sensitivity of NMDARs but not AMPARs/kainate receptors to the endogenous inhibitory neurosteroid 20-oxo-5b-pregnan-3a-yl 3-sulfate and to its synthetic analogs, such as 20-oxo-5b-pregnan-3a-yl 3-hemipimelate (PAhPim). In cultured hippocampal neurons, 30 lM PAhPim had virtually no effect on NMDAR responses; however, following the Ca21 challenge, it inhibited the responses by 62%; similarly, the Ca2+ challenge induced a 3.7-fold decrease in the steroid IC50 on recombinant GluN1/GluN2B receptors. The increase in the NMDAR sensitivity to PAhPim was dependent on three cysteines (C849, C854, and C871) located in the carboxy-terminal domain of the GluN2B subunit, previously identified to be palmitoylated (Hayashi et al., 2009). Our experiments suggested that the Ca2+ challenge induced receptor depalmitoylation, and single-channel analysis revealed that this was accompanied by a 55% reduction in the probability of channel opening. Results of in silico modeling indicate that receptor palmitoylation promotes anchoring of the GluN2B subunit carboxy-terminal domain to the plasma membrane and facilitates channel opening. Depalmitoylation-induced changes in the NMDAR pharmacology explain the neuroprotective effect of PAhPim on NMDA-induced excitotoxicity. We propose that palmitoylation-dependent changes in the NMDAR sensitivity to steroids serve as an acute endogenous mechanism that controls NMDAR activity. [ABSTRACT FROM AUTHOR]

Currently there is no consensus regarding the aetiology of the excessive ocular volume that characterizes high myopia. Thus, we aimed to test whether the gene pathways identified by gene set enrichment analysis of RNA-seq transcriptomics refutes the predictions of the Retinal Ion Driven Efflux (RIDE) hypothesis when applied to the induction of form-deprivation myopia (FDM) and subsequent recovery (post-occluder removal). We found that the induction of profound FDM led to significant suppression in the ligand-gated chloride ion channel transport pathway via suppression of glycine, GABAA and GABAC ionotropic receptors. Post-occluder removal for short term recovery from FDM of 6 h and 24 h, induced significant upregulation of the gene families linked to cone receptor phototransduction, mitochondrial energy, and complement pathways. These findings support a model of form deprivation myopia as a Cl− ion driven adaptive fluid response to the modulation of the visual signal cascade by form deprivation that in turn affects the resultant ionic environment of the outer and inner retinal tissues, axial and vitreal elongation as predicted by the RIDE model. Occluder removal and return to normal light conditions led to return to more normal upregulation of phototransduction, slowed growth rate, refractive recovery and apparent return towards physiological homeostasis. [ABSTRACT FROM AUTHOR]

Advances in molecular and cellular biology, as well as the development of chemical synthesis and modern technologies, enriched the contemporary experimental research with new directions in which light plays a key role as a tool for modulating biological functions. One of them is photopharmacology, a field that uses chemically synthesized light-controlled compounds that can modulate the functions of proteins. When illuminated at specific wavelengths, these synthetic photoswitches are capable of modulating functions of receptors, ion channels and enzymes. This review briefly describes compounds that modulate the functions of ionotropic Cys-loop receptors for acetylcholine, GABA, and glycine. The nicotinic acetylcholine receptor (nAChR) is the first receptor-operated channel for which a way of modulation using light-dependent molecules has been discovered. In the 1970s–80s, blockers and activators of nAChR were created, consisting of azobenzene (light-controlled switch) and agonists. In the current millennium, new compounds have been created to provide light-controlled modulation of nAChR activity. These new photochromes are selective to muscle and neuronal nAChR, and are promising to study the physiological role of nAChRs in the nervous system. An extensive library of photochromic compounds is available for light-controlling of GABA receptor function. Some of them modulate the activity via interaction with the agonist site, the others are light-controlled blockers of chloride-selective ion channels. Recently, the first two photochromic modulators of glycine receptor activity have also been developed. These achievements demonstrate that photopharmacology opens up unique possibilities for remote control of physiological functions, as well as for studying the processes of inhibition and excitation in neural networks and models of neuronal pathologies. [ABSTRACT FROM AUTHOR]

Breast cancer is currently the most common cancer and the leading cause of cancer death among women worldwide. Advanced breast cancer is prone to metastasis, and there is currently no drug to cure metastatic breast cancer. The purinergic ligand-gated ion channel 7 receptor is an ATP-gated nonselective cation channel receptor and is involved in signal transduction, growth regulation, cytokine secretion, and tumor cell development. Recent studies have shown that upregulation of the P2X7 receptor in breast cancer can mediate AKT signaling pathways, Ca2 þ-activated SK3 potassium channels, and EMT and regulate the secretion of small extracellular vesicles to promote breast cancer invasion and migration, which are affected by factors such as hypoxia and ATP. In addition, studies have shown that microRNAs can bind to the 3′ untranslated region of the P2X7 receptor, which affects the occurrence and development of breast cancer by upregulating and downregulating P2X7 receptor expression. Studies have shown that new P2X7 receptor inhibitors, such as emodin and Uncaria tomentosa, can inhibit P2X7 receptor-mediated breast cancer invasion and are expected to be used clinically. This article reviews the research progress on the relationship between the P2X7 receptor and breast cancer to provide new ideas and a basis for clinical diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Five different subunits of the human serotonin 3 (5-hydroxytrptamine 3; 5-HT3) receptor exist and these are present in both central and peripheral systems. Different subunits alter the efficacy of 5-HT3 receptor antagonists used to treat diarrhoea predominant-irritable bowel syndrome, chemotherapy induced nausea and vomiting and depression. Cell surface arrangement of 5-HT3 receptor complexes and the contribution of C, D and E subunits to receptor function is poorly understood. Here, we examine interactions of A and C subunits using 5-HT3 receptor subunits containing fluorescent protein inserts between the 3rd and 4th transmembrane spanning region. HEK293T cells that do not normally express 5-HT3 receptor subunits, were transiently transfected with A or C or both subunits. Patch clamp experiments show that cells transfected with either fluorescent protein tagged A or A and C subunits generate whole cell currents in response to 5-HT. These findings correlate with the apparent distribution of fluorescent protein tagged A and C subunits at or near cell surfaces detected using TIRF microscopy. In co-transfected cells, the A and C subunits are associated forming AC heteromer complexes at or near the cell surface and a proportion can also form A or C homomers. In conclusion, it is likely that both A homomers and AC heteromers contribute to whole cell currents in response to 5-HT with minimal contribution from C homomers.

Alcohol abuse and dependence have a staggering socioeconomic impact, yet current therapeutic strategies are largely inadequate to treat these disorders. Thus, the development of new strategies that can effectively prevent alcohol use disorders (AUDs) is of paramount importance. Currently approved medications attempt to deter alcohol intake by blocking ethanol metabolism or by targeting the neurochemical systems downstream of the cascades leading to craving and dependence. Unfortunately, these medications have provided only limited success as indicated by the continued high rates of alcohol abuse and alcoholism. The lack of currently available effective treatment strategies is highlighted by the urgent call by the NIAAA to find new and paradigm-changing therapeutics to either prevent or treat alcohol-related problems. This mini-review highlights recent findings from 4 laboratories with a focus on compounds that have the potential to be novel therapeutic agents that can be developed for the prevention and/or treatment of AUDs.