• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.857-863
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• 2023

Pathogenic bacteria that colonize the human intestinal tract have evolved strategies to overcome acidic conditions when they pass through the gastrointestinal tract. Amino acid-mediated acid resistance systems are effective survival strategies in a stomach that is full of amino acid substrate. The amino acid antiporter, amino acid decarboxylase, and ClC chloride antiporter are all engaged in these systems, and each one plays a role in protecting against or adapting to the acidic environment. The ClC chloride antiporter, a member of the ClC channel family, eliminates negatively charged intracellular chloride ions to avoid inner membrane hyperpolarization as an electrical shunt of the acid resistance system. In this review, we will discuss the structure and function of the prokaryotic ClC chloride antiporter of amino acid-mediated acid resistance system.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.4
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• pp.439-447
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• 2017

Myotonia congenita (MC) is a genetic disease that displays impaired relaxation of skeletal muscle and muscle hypertrophy. This disease is mainly caused by mutations of CLCN1 that encodes human skeletal muscle chloride channel (CLC-1). CLC-1 is a voltage gated chloride channel that activates upon depolarizing potentials and play a major role in stabilization of resting membrane potentials in skeletal muscle. In this study, we report 4 unrelated Korean patients diagnosed with myotonia congenita and their clinical features. Sequence analysis of all coding regions of the patients was performed and mutation, R47W and A298T, was commonly identified. The patients commonly displayed transient muscle weakness and only one patient was diagnosed with autosomal dominant type of myotonia congenita. To investigate the pathological role of the mutation, electrophysiological analysis was also performed in HEK 293 cells transiently expressing homo-or heterodimeric mutant channels. The mutant channels displayed reduced chloride current density and altered channel gating. However, the effect of A298T on channel gating was reduced with the presence of R47W in the same allele. This analysis suggests that impaired CLC-1 channel function can cause myotonia congenita and that R47W has a protective effect on A298T in relation to channel gating. Our results provide clinical features of Korean myotonia congenita patients who have the heterozygous mutation and reveal underlying pathophyological consequences of the mutants by taking electrophysiological approach.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.574-580
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• 2007

Full-length chloride intracellular channel protein 1 (CLIC1) is a member of the family of proteins related to bovine chloride intracellular channel p64. Mutations in the SEDL gene cause spondyloepiphyseal dysplasia tarda (SEDT), a rare X-linked chondrodysplasia. The link between the intracellular chloride channels and SEDL is an important step toward understanding their functional interplay. In the present study, CLIC1 protein was subcloned into the pGEX-KG vector and overexpressed in XL-1 blue cells. We developed a large-scale expression system composed of glutathione S-transferase (GST) fused with a 240-amino-acid CLIC1 protein in Escherichia coli. The soluble CLIC1 protein was successfully purified to homogeneity, and its purity, identity, activity and conformation were determined using SDS-PAGE, MALDI-MS, biophotometer and circular dichroism spectroscopic studies. The binding of both CLIC1 and SEDL proteins in vitro was detected by BIAcore biosensor and fluorescence measurements.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.101-112
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• 2004

Chloride($Cl^-$) channels play critical roles in cell homeostasis and its specific functions such as volume regulation, differentiation, secretion, and membrane stabilization. The presence of these channels have been reported in all kinds of cells and even in frog oocytes. These essential role of $Cl^-$­ channels in cell homeostasis possibly play any role in egg homeostasis and in the early stage of development, however, there has been no report about the presence of $Cl^-$­ channel in the mammalian oocyte. This study was performed to elucidate the presence of $Cl^-$­ channels in hamster eggs. When allowing only $Cl^-$­ to pass through the channel of the egg membrane by using impermeant cation such as N-methyl-D-glucamine(NMDG), single channel currents were recorded. These channel currents showed typical long-lasted openings interrupted by rapid flickering. Mean open $time({\tau}o)$ was 43${\pm}$10.14 ms(n=9, at 50 mV). The open probability(Po) was decrease with depolarization. The current-voltage relation showed outward rectification. Outward slop conductance(32${\pm}$5.4 pS, n=22) was steeper than the inward slop conductance(10${\pm}$1.3 pS). Under the condition of symmetrical 140 mM NaCl, single channel currents were reversed at 0 mV(n=4). This reversal potential(Erev) was shifted from 0 mV at 140 mM concentration of internal NaCl(140 mM [Na+]i) to ­9.8${\pm}$0.5 mV(n=4) at 70 mM [Na+]i and 11.5${\pm}$1.9 mV at 280 mM [Na+]i(n=4) respectively, strongly suggesting that these are single $Cl^-$­ channel currents. To examine further whether this channel has pharmacological property of the $Cl^-$­ channel, specific Cl­ channel blockers, IAA-94(Indanyloxyacetic acid-94) and DIDS(4, 4'-diisothiocyan ostillben- 2-2'disulfonic acid) were applied. IAA-94 inhibited the channel current in a dose-dependent manner and revealed a rapid and flickering block. From these electrophysiological and pharmacological resluts, we found the novel $Cl^-$­ channel present in the hamster oocyte membrane. The first identification of $Cl^-$­ channel in the hamster oocyte may give a clue for the further study on the function of $Cl^-$­ channel in the fertilization and cell differentiation.

• Proceedings of the PSK Conference
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• 2002.04a
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• pp.145.1-145.1
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• 2002

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.21-28
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• 2014

In this study, evaluated ware the strength and durability of the vegetated water purification channel concrete to which recycled aggregates, hawang-toh and jute were applied. Box-Behnken method of response surface analysis in statistics was applied to the experimental design. Experimental variables are as follows, recycled coarse aggregates, hawang-toh, blast-furnace slag and jute fiber. In the experiment, conducted were the tests of compressive strength, chloride ion penetration, abrasion resistance and impact resistance the replacement rate effects of the recycled aggregates, blast-furnace slag and hwang-toh on the performance of vegetated water purification channel concrete were analyzed by using the response surface analysis method on the basis of the experimental results. In addition, an optimum mixing ratio of vegetated water purification channel concrete was determined by using the experimental results. The optimum mixing ratio was determined to be in 10.0% recycled coarse aggregates, 60.0% blast-furnace slag, 10.1% hwang-toh and 0.16% jute fiber. The compressive strength, chloride ion penetration, abrasion rate, and impact number of fracture test results of the optimum mixing ratio were 24.1 MPa, 999 coulombs, 10.30 g/mm3, and 20 number, respectively.

• Journal of Ginseng Research
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• v.29 no.4
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• pp.167-175
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• 2005

The $Ca^{2+}-activated$ chloride channel (CLCA) was activated by ginseng total saponin (GTS) in Xenopus oocytes. The reverse transcription PCR (RT-PCR) method was performed with gene specific primers on oocytes. The gene specific primers were deduced from spleen cDNA in expressed sequence tags (EST) database showing high homology to the mouse CLCA. Full length of cDNA sequence was completed by linkage of several 5' and 3'-half cDNA fragments have been sequenced. We named the full cDNA to oCLCA transiently. The oCLCA gene encodes a protein of 911 amino acids with $48.9\%$ identity overall to that of mouse CLCA (mCLCA4). A predicted oCLCA amino acids sequence shows the molecular weight of 108 kDa and has four or more transmembrane domains, and also the one hydrophobic C­terminal domain. oCLCA gene was expressed ubiquitously in various tissues included oocytes, also interfered in oocytes by siRNA for oCLCA. Here, we suggest that oCLCA is a endogenous chloride channel gene in oocytes. We are studying for the identification of oCLCA gene and further physiological research.

• Journal of Periodontal and Implant Science
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• v.45 no.2
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• pp.69-75
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• 2015

Purpose: Salivary fluid formation is primarily driven by Ca2+-activated, apical efflux of chloride into the lumen of the salivary acinus. The anoctamin1 protein is an anion channel with properties resembling the endogenous calcium-activated chloride channels. In order to better understand the role of anoctamin proteins in salivary exocrine secretion, the expression of the ten members of the anoctamin gene family in the mouse submandibular gland was studied. Methods: Total RNA extracted from mouse submandibular salivary glands was reverse transcribed using primer pairs to amplify the full-length coding regions of each anoctamin gene and was subcloned into plasmid vectors for DNA sequencing. Alternative splice variants were also screened by polymerase chain reaction using primer pairs that amplified six overlapping regions of the complementary DNA of each anoctamin gene, spanning multiple exons. Results: Multiple anoctamin transcripts were found in the mouse submandibular salivary gland, including full-length transcripts of anoctamin1, anoctamin3, anoctamin4, anoctamin5, anoctamin6, anoctamin9, and anoctamin10. Exon-skipping splicing in the N-terminal exons of the anoctamins1, anoctamin5, and anoctamin6 genes resulted in multiple alternative splice variants. No expression of anoctamin2, anoctamin7, or anoctamin8 was found. Conclusions: The predominant anoctamin transcript expressed in the mouse submandibular gland is anoctamin1ac. The chloride channel protein produced by anoctamin1ac is likely responsible for the $Ca^{2+}$-activated chloride efflux, which is the rate-limiting step in salivary exocrine secretion.

• Korean Journal of Veterinary Research
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• v.34 no.1
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• pp.25-36
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• 1994

The inward tail current after a short depolarizing pulse has been known as Na-Ca exchange current activated by intracellular calcium which forms late plateau of the action potential in rabbit atrial myocytes. Chloride conductance which is also dependent upon calcium concentration has been reported as a possible tail current in many other excitable tissues. Thus, in order to investigate the exsitance of the calcium activated chloride current and its contribution to tail current, whole cell voltage clamp measurement has been made in single atrial cells of the rabbit. The current was recorded during repolarization following a brief 2 ms depolarizing pulse to +40mV from a holding potential of -70mV. When voltage-sensitive transient outward current was blocked by 2 mM 4-aminopyridine or replacement potassium with cesium, the tail current were abolished by ryanodine$(1{\mu}M)$ or diltiazem$(10{\mu}M)$ and turned out to be calcium dependent. The magnitudes of the tail currents were increased when intracellular chloride concentration was increased to 131 mM from 21 mM. The current was decreased by extracellular sodium reduction when intracellular chloride concentration was low(21 mM), but it was little affected by extracellular sodium reduction when intracellual chloride concentration was high(131 mM). The current-voltage relationship of the difference current before and after extracellular sodium reduction, shows an exponential voltage dependence with the largest magnitude of the current occurring at negative potentials, with is similar to current-voltage relationship at negative potentials, which is similar to current-voltage relationship of Na-Ca exchange current. The current was also decreased by $10{\mu}M$ niflumic acid and 1 mM bumetanide, which is well known anion channel blockers. The reversal potentials shifted according to changes in chloride concentration. The current-voltage relationships of the niflumic acid-sensitive currents in high and low concentration of chloride were well fitted to those predicted as chloride current. From the above results, it is concluded that calcium activated chloride component exists in the tail current with Na-Ca exchange current and it shows the reversal of tail current. Therefore it is thought that in the physiologic condition it leads to rapid end of action potential which inhibits calcium influx and it contributes to maintain the low intracellular calcium concentration with Na-Ca exchange mechanism.

• BMB Reports
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• v.50 no.3
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• pp.109-110
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• 2017

The nature of encoded information in neural circuits is determined by neuronal firing patterns and frequencies. This paper discusses the molecular identity and cellular mechanisms of spike-frequency adaptation in the central nervous system (CNS). Spike-frequency adaptation in thalamocortical (TC) and CA1 hippocampal neurons is mediated by the $Ca^{2+}$-activated $Cl^-$ channel (CACC) anoctamin-2 (ANO2). Knockdown of ANO2 in these neurons results in increased number of spikes, in conjunction with significantly reduced spike-frequency adaptation. No study has so far demonstrated that CACCs mediate afterhyperpolarization currents, which result in the modulation of neuronal spike patterns in the CNS. Our study therefore proposes a novel role for ANO2 in spike-frequency adaptation and transmission of information in the brain.