Cl Ion Channels Research Articles

Advanced Molecular Mechanisms of Epilepsy

The Central Nervous System (CNS) is a complex network composed of the cerebral cortex and the vertebral column, orchestrating intricate processes through neural networks and chemical regulation. Neurotransmission in the CNS involves neurotransmitters, neuromodulators, neuromediators, and neurotropic factors, playing distinct roles in cellular activity and synaptic plasticity. Various neurotransmitters such as dopamine, glutamate, GABA, glycine, serotonin, and others exert diverse effects on the CNS through specific receptors, influencing synaptic transmission and neuronal excitability. GABA, the primary inhibitory neurotransmitter, acts via GABA-A and GABA-B receptors, modulating Cl-ion channels and second messenger systems, impacting seizure activity and CNS function. Epilepsy, a neurological disorder characterized by abnormal brain activity leading to recurrent seizures, results from an imbalance between excitatory (glutamate) and inhibitory (GABA) systems. The pathophysiology involves neuronal hyperexcitability, disrupted ion channels, and neurotransmitter imbalances, leading to seizures with varying symptoms and severity. The etiology of epilepsy encompasses genetic predisposition, head injuries, brain disorders, infections, prenatal injuries, and developmental disorders. Treatment options include medications, surgery, brain stimulation therapies, and dietary interventions like the ketogenic diet Understanding the mechanisms underlying epilepsy involves exploring neurotransmitter interactions, ion channel dynamics, and neuroendocrine modulation. Neuropeptide Y (NPY) and steroid hormones, such as testosterone and estrogen, play roles in seizure susceptibility, offering potential avenues for therapeutic intervention. In conclusion, unravelling the complexities of the CNS and epilepsy involves deciphering intricate neural pathways, neurotransmitter functions, and hormonal influences. Developing targeted therapies that modulate these intricate systems may offer promising approaches for managing epilepsy and related neurological conditions.

NeuronX - NEventSpace single neuron model of the soliton spike of mimosa pudica as Ca, Na, K, Cl ion channels in NEURON script of Yale University in python.

NeuronX - NEventSpace single neuron model of the soliton spike of mimosa pudica as Ca, Na, K, Cl ion channels in NEURON script of Yale University in python.

Cytotoxicity of glucoevatromonoside alone and in combination with chemotherapy drugs and their effects on Na+,K+-ATPase and ion channels on lung cancer cells.

Cardiac glycosides (CGs) are useful drugs to treat cardiac illnesses and have potent cytotoxic and anticancer effects in cultured cells and animal models. Their receptor is the Na+,K+ ATPase, but other plasma membrane proteins might bind CGs as well. Herein, we evaluated the short- and long-lasting cytotoxic effects of the natural cardenolide glucoevatromonoside (GEV) on non-small-cell lung cancer H460 cells. We also tested GEV effects on Na+,K+ -ATPase activity and membrane currents, alone or in combination with selected chemotherapy drugs. GEV reduced viability, migration, and invasion of H460 cells spheroids. It also induced cell cycle arrest and death and reduced the clonogenic survival and cumulative population doubling. GEV inhibited Na+,K+-ATPase activity on A549 and H460 cells and purified pig kidney cells membrane. However, it showed no activity on the human red blood cell plasma membrane. Additionally, GEV triggered a Cl-mediated conductance on H460 cells without affecting the transient voltage-gated sodium current. The administration of GEV in combination with the chemotherapeutic drugs paclitaxel (PAC), cisplatin (CIS), irinotecan (IRI), and etoposide (ETO) showed synergistic antiproliferative effects, especially when combined with GEV + CIS and GEV + PAC. Taken together, our results demonstrate that GEV is a potential drug for cancer therapy because it reduces lung cancer H460 cell viability, migration, and invasion. Our results also reveal a link between the Na+,K+-ATPase and Cl-ion channels.

Fabrication of magnetic nanochains linked with CTX and curcumin for dual modal imaging detection and limitation of early tumour.

Five-year survival rate at early lung tumour was about 70%; however, its early diagnosis rate was still at a low level, so the enhancement of diagnosis level for early lung tumour is the key factor to increase the survival rate. Diagnosis and therapy of early lung tumour are still challenged. The magnetic nanochains (NCs) with biocompatibility and transverse relaxivity (r2 =231 Fe mmoll-1 s-1 ) were fabricated through a co-precipitation method in the assistance of dextran, and then, linked with chlorotoxin (CTX) and curcumin (Cur) via the PEGylation and carbodiimide technique (named as CTX-NCs-Cur). The results of cell test indicated that CTX-conjugated NCs could obviously target non-small-cell lung cancer cells and limit their growth. The in vivo results of magnetic resonance imaging and fluorescence imaging indicated that the CTX-NCs-Cur significantly targeted the tumour site and enhanced images contrast of the small-size tumour. Moreover, the results of everyday tail-vein injection confirmed that CTX-NCs-Cur could significantly limit the growth of early tumour, due to blocking Cl ion channels from CTX-NCs-Cur-MMP-2 composite and intracellular ROS increase from Cur treatment. We provided a mechanism about the effect of CTX-NCs-Cur on the targeting and limiting early tumour, and these results indicated the application foreground of CTX-NCs-Cur in tumour diagnosis and therapy.

Niflumic Acid Inhibits Goblet Cell Degranulation in a Guinea Pig Asthma Model

Human Ca(2+)-activated Cl ion channel 1 (hCLCA1) is expressed in goblet cell hyperplasia in the airway of asthmatics, and murine CLCA3 is associated with antigen-sensitized and IL-13-induced goblet cell metaplasia in mice. However, the role of CLCA in goblet cell degranulation is not fully investigated. Niflumic acid (NFA), a relatively specific CLCA inhibitor, inhibits goblet cell metaplasia, but the effect of NFA on goblet cell degranulation has not been determined in an asthma model. Guinea pigs were sensitized with ovalbumin (OA) twice and then challenged with saline, OA, histamine, and one of the Ca(2+)-dependent secretagogues, UTP. The PAS/AB-stained mucus area in the tracheal epithelium was measured with a computer image analysis system, and the morphology of mucus granules was examined by transmission electron microscopy. In the in vitro experiment, goblet cells cultured with IL-13 at the air-liquid interface were stimulated with UTP in the presence or absence of NFA, and the MUC5AC level in cell lysates was measured by ELISA. The mucus areas were smaller in the OA-, histamine-, and UTP-challenged animals than in the saline-challenged animals. NFA inhibited the decrease in mucus area and morphological changes in mucus granules. UTP caused swelling and exocytosis of mucus granules and MUC5AC secretion by cultured goblet cells, and NFA inhibited these changes. NFA inhibited the secretory response of mucus granules in an asthma model, suggesting that CLCA may be associated with goblet cell degranulation and that CLCA inhibitors may be useful for the treatment of hypersecretion in asthma.

The role of the UPS in cystic fibrosis

CF is an inherited autosomal recessive disease whose lethality arises from malfunction of CFTR, a single chloride (Cl-) ion channel protein. CF patients harbor mutations in the CFTR gene that lead to misfolding of the resulting CFTR protein, rendering it inactive and mislocalized. Hundreds of CF-related mutations have been identified, many of which abrogate CFTR folding in the endoplasmic reticulum (ER). More than 70% of patients harbor the ΔF508 CFTR mutation that causes misfolding of the CFTR proteins. Consequently, mutant CFTR is unable to reach the apical plasma membrane of epithelial cells that line the lungs and gut, and is instead targeted for degradation by the UPS. Proteins located in both the cytoplasm and ER membrane are believed to identify misfolded CFTR for UPS-mediated degradation. The aberrantly folded CFTR protein then undergoes polyubiquitylation, carried out by an E1-E2-E3 ubiquitin ligase system, leading to degradation by the 26S proteasome. This ubiquitin-dependent loss of misfolded CFTR protein can be inhibited by the application of ‘corrector’ drugs that aid CFTR folding, shielding it from the UPS machinery. Corrector molecules elevate cellular CFTR protein levels by protecting the protein from degradation and aiding folding, promoting its maturation and localization to the apical plasma membrane. Combinatory application of corrector drugs with activator molecules that enhance CFTR Cl- ion channel activity offers significant potential for treatment of CF patients.Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; ).

Cocaine: evidence for NMDA-, β-carboline- and dopaminergic-mediated seizures in mice

The present study was undertaken to examine the role of the benzodiazepine/GABA and N-methyl- d-aspartate (NMDA) systems in the convulsive effect of cocaine in mice. When cocaine (3.5 mg/ml) solution was infused into the tail vein at a rate of 0.3 ml/min, mice showed clonic and tonic convulsions. These seizures were not affected by low doses of bicuculline or picrotoxin, a GABA A receptor antagonist and a Cl ion channel blocker, respectively. Aminooxyacetic acid (AOAA), a GABA deaminase inhibitor, and phenobarbital, a Cl ion channel activator, and baclofen, a GABA B receptor agonist, also had no effect on these convulsions. Benzodiazepine inverse agonist β-DMCM, at a dose which by itself had no convulsive effect lowered the convulsive threshold of cocaine. This lowered convulsive threshold was reversed by flumazenil, a benzodiazepine inverse antagonist, and diazepam, a benzodiazepine full agonist, which by themselves did not inhibit cocaine seizure. It is likely that cocaine seizure involves a benzodiazepine ( β-carboline) recognition site other than the benzodiazepine/GABA A receptor–Cl ionophore complex system. CPP and MK-801, competitive and noncompetitive NMDA receptor antagonists, respectively, inhibited cocaine seizures. The inhibitory effects of CPP on cocaine convulsion were reversed by a low dose of NMDA, which by itself did not induce seizure. A dopamine D 1 receptor agonist SKF38393 enhanced both clonic and tonic convulsions, while a dopamine D 2 receptor agonist bromocriptine inhibited these convulsions. These stimulatory and inhibitory effects were reversed by the D 1 and D 2 receptor antagonists, SCH23390 and haloperidol, respectively. These results suggest that the cocaine-induced convulsion may involve an activation of the NMDA–Ca ionophore complex system, which is mediated by the dopaminergic system, and a β-carboline recognition site other than the benzodiazepine/GABA A receptor–Cl ionophore complex system.

Transcriptional activation of mucin by Pseudomonas aeruginosa lipopolysaccharide in the pathogenesis of cystic fibrosis lung disease.

An unresolved question in cystic fibrosis (CF) research is how mutations of the CF transmembrane conductance regulator, a Cl ion channel, cause airway mucus obstruction leading to fatal lung disease. Recent evidence has linked the CF transmembrane conductance regulator mutation to the onset and persistence of Pseudomonas aeruginosa infection in the airways, and here we provide evidence directly linking P. aeruginosa infection to mucus overproduction. We show that P. aeruginosa lipopolysaccharide profoundly upregulates transcription of the mucin gene MUC 2 in epithelial cells via inducible enhancer elements and that this effect is blocked by the tyrosine kinase inhibitors genistein and tyr-phostin AG 126. These findings improve our understanding of CF pathogenesis and suggest that the attenuation of mucin production by lipopolysaccharide antagonists and tyrosine kinase inhibitors could reduce morbidity and mortality in this disease.

The CFTR chloride channel of mammalian heart.

Cystic fibrosis (CF), the most prevalent fatal genetic disease among Cauca­ sians, is caused by alterations in the single gene encoding the cystic fibrosis transmembrane conductance regulator (CFfR; 114). The gene alterations result in defective epithelial Cltransport and, consequently, a disruption of fluid secretion in respiratory, intestinal, and reproductive epithelia, and of salt reab­ sorption in sweat glands (109), A single mutation, deletion of the three nucleic acids that code for phenylalanine 508, accounts for two thirds of all diagnosed cases of CF (136), but over 300 other disease-causing mutations have been identified so far. CFfR is now known to be a Clion channel, although, as its name implies, this was not at all clear from the deduced amino acid sequence (1 14). CFfR's predicted topology (Figure 1; 114) of two similar halves, each comprising six putative transmembrane stretches followed by an intracellular nucleotide-bind­ ing domain (NBD), linked by a large intracellular regulatory (R) domain containing mUltiple sites for phosphorylation by protein kinase A (PKA) and protein kinase C (PKC), placed it in the large family of A TP-binding cassette (ABC) tfansport proteins (71). The ABC family includes numerous bacterial peri plasmic transporters as well as eukaryotic members such as the exporter (STE6) of the yeast a-factor mating pheromone, and the mammalian P-glyco-

K and Cl ion channels in the aqueous-facing membrane of the rat ciliary body epithelium

Iodide efflux, an index of anion permeability, has been monitored in cultured rat brain endothelial cells. Following hypotonicity-induced swelling, large, rapid increases in permeability occur, the extent of these increases depending on the degree of hypotonicity. Such large responses are not observed with rat aortic endothelial cells. Results of anion substitution experiments suggest that iodide efflux is via a chloride channel rather than an exchanger. The efflux increase is blocked by NPPB (100 μM) but not by DIDS or DPC at 100 μM. It is dependent on intracellular ATP but unaffected by removal of external calcium. Increasing internal calcium using A23187 does not produce a change in efflux, but depletion of calcium reduces or eliminates the response to hypotonicity. The response is reduced by pimozide (2–50 μM) that inhibits the actions of calmodulin and by pBPB (10 μM) that affects phospholipase A2 activity. It is eliminated by 5-lipoxygenase inhibitors (L-656,224 and ETH615, 10 μM) but is unaffected by cyclo-oxygenase inhibitors (indomethacin and piroxicam, 1–100 μM). It is blocked by some modulators of P-glycoprotein activity, e.g., verapamil (100 μM), tamoxifen (50 μM), and progesterone (100 μM) but not by others, e,g., forskolin (40 μM), dideoxyforskolin (40 μM), quinidine (100 μM) and cyclosporin A (10 μM).

Direct action of ethanol on cerebral GABA A receptor complex: Analysis using purified and reconstituted GABA A receptor complex

Possible direct action of ethanol on cerebral GABA A receptor complex has been analyzed using reconstituted vesicles with purified GABA A/benzodiazepine receptor/Cl ion channel complex prepared from the bovine cerebral cortex. Addition of ethanol to the reconstituted vesicles with purified GABA A receptor complex induced a significant facilitation of GABA-dependent 36Cl − influx in a dose-dependent manner. Furthermore, the reconstituted vesicles with pretreated GABA A receptor complex with 20 mM ethanol, a dose that had no significant effect on GABA A receptor binding, also exhibited a significant increase of GABA-dependent 36Cl influx as compared with that found in non-treated preparation. On the other hand, the facilitation of GABA-dependent 36Cl − influx by flunitrazepam was found to be eliminated by the ethanol pretreatment. The present results suggest that ethanol may affect directly on GABA A receptor complex and facilitate the function of Cl ion channel but eliminate or decrease the functional coupling between benzodiazepine receptor and GABA A receptor.

Release of aspartate and glutamate caused by chloride reduction in synaptosomal incubation media.

Release of the amino acid neurotransmitter candidates aspartate and glutamate from synaptosomes can be stimulated by reduction of [Cl-] in the incubation medium by replacement with the impermeant anions propionate and isethionate. Replacement by the permeant anion Br- is without effect on amino acid release. This release offers a biochemical method of studying the Cl-ion channel in CNS membrane.