• BMB Reports
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• v.51 no.5
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• pp.236-241
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• 2018

Anoctamin 1 (ANO1) is an anion channel that is activated by changes in cytosolic $Ca^{2+}$ concentration and noxious heat. Although the critical roles of ANO1 have been elucidated in various cell types, the control of its gating mechanisms by $Ca^{2+}$ and heat remain more elusive. To investigate critical amino acid residues for modulation of $Ca^{2+}$ and heat sensing, we constructed a randomized mutant library for ANO1. Among 695 random mutants, reduced $Ca^{2+}$ sensitivity was observed in two mutants (mutant 84 and 87). Consequently, the E143A mutant showed reduced sensitivity to $Ca^{2+}$ but not to high temperatures, whereas the E705V mutant exhibited reduced sensitivity to both $Ca^{2+}$ and noxious heat. These results suggest that the glutamic acids (E) at 143 and 705 residues in ANO1 are critical for modulation of $Ca^{2+}$ and/or heat responses. Furthermore, these findings help to provide a better understanding of the $Ca^{2+}$-mediated activation and heat-sensing mechanism of ANO1.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.34-34
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• 2002

Oxidative stress has been considered as a major cause of inducing cell damage, but it is recently recognized that mild oxidative stress or receptor-mediated production of ROS contributes to the regulation of various cellular functions. Several ion channels, such as L-type $Ca^{2＋}$ channels and $Ca^{2＋}$-activated $K^{＋}$ channels, have been shown to be regulated by oxidation of thiol group in their structure, and are suggested to be involved in ROS-sensitive cellular signaling.(omitted)

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.4
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• pp.287-298
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• 2020

Ca²⁺ signaling of endothelial cells plays a critical role in controlling blood flow and pressure in small arteries and arterioles. As the impairment of endothelial function is closely associated with cardiovascular diseases (e.g., atherosclerosis, stroke, and hypertension), endothelial Ca²⁺ signaling mechanisms have received substantial attention. Increases in endothelial intracellular Ca²⁺ concentrations promote the synthesis and release of endothelial-derived hyperpolarizing factors (EDHFs, e.g., nitric oxide, prostacyclin, or K⁺ efflux) or directly result in endothelial-dependent hyperpolarization (EDH). These physiological alterations modulate vascular contractility and cause marked vasodilation in resistance arteries. Transient receptor potential (TRP) channels are nonselective cation channels that are present in the endothelium, vascular smooth muscle cells, or perivascular/sensory nerves. TRP channels are activated by diverse stimuli and are considered key biological apparatuses for the Ca²⁺ influx-dependent regulation of vasomotor reactivity in resistance arteries. Ca²⁺-permeable TRP channels, which are primarily found at spatially restricted microdomains in endothelial cells (e.g., myoendothelial projections), have a large unitary or binary conductance and contribute to EDHFs or EDH-induced vasodilation in concert with the activation of intermediate/small conductance Ca²⁺-sensitive K⁺ channels. It is likely that endothelial TRP channel dysfunction is related to the dysregulation of endothelial Ca²⁺ signaling and in turn gives rise to vascular-related diseases such as hypertension. Thus, investigations on the role of Ca²⁺ dynamics via TRP channels in endothelial cells are required to further comprehend how vascular tone or perfusion pressure are regulated in normal and pathophysiological conditions.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.437-446
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• 1999

Porphyromonas endodontalis(P. endodontalis) is one of the important causative bacteria of pulpal and periapical disease. P. endodontalis has lipopolysaccharide(LPS) and it plays a major role in stimulating the synthesis and release of cytokines from immune cells and prostaglandin $E_2$ from host cells. The purpose of this study is to prepare LPS from P. endodontalis and to evaluate the effect of LPS on membrane permeability of fibroblast. P. endodontalis ATCC 35406 was cultured in anaerobic condition, and LPS was extracted. LPS was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Human periodontal ligament cell, colon fibroblast(CCD-18Co, KCLB 21459) and skin fibroblast(Detroit 551, KCLB 10110) were perfused with 0.01% P. endodontalis LPS solution, high concentration of $K^+$ solution and $Ca^{2+}$-free solution, $Ca^{2+}$ concentration ratio was measured by microfluorometry. 1. Intracellular $Ca^{2+}$ concentration was not changed in human periodontal fibroblast and skin fibroblast(Detroit 551) stimulated by P. endodontalis LPS. 2. Intracellular $Ca^{2+}$ concentration was increased in colon fibroblast(CCD-18Co) stimulated by P. endodontalis LPS. 3. Colon fibroblast(CCD-18Co) has voltage dependent $Ca^{2+}$ channel activated by high concentration of $K^+$ solution. 4. P. endodontalis LPS has no effect on the increase of intracellular $Ca^{2+}$ concentration during perfusion of $Ca^{2+}$-free solution.

• Biomolecules & Therapeutics
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• v.8 no.2
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• pp.113-118
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• 2000

TEA, glibenclamide, L-NAME and SKF 525A-induced reversible contraction were investigated using acetylcholine, sodium nitroprusside (SNP) and pinacidil in rat abdominal and thoracic aorta. Acetylcho-line, SNP or pinacidil produced in a dose dependent manner relaxation on phenylephrine-induced contraction In rat aorta. TEA, SKF 525A, and L-NAME produced reversible contractions on acetylcholine-induced relaxation, but not on SNP- or pinacidil-induced relaxation. Glibenclamide significantly produced reversible con- traction on pinacidll-induced relaxation. The reversible effect of TEA on the acetylcholine-induced relaxation was reduced by SKF 525A. These results indicate that the acetylcholine-induced relaxation may be mediated by NO, cytochrome P$_{450}$-dependent epoxygenase pathway, or $Ca^{2+}$ activated $K^{+}$ channel, and the pinacidil-induced relaxation may be mediated by ATP-sensitive $K^{+}$ channel.annel.

• Journal of Life Science
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• v.17 no.8 s.88
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• pp.1053-1062
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• 2007

In the present work, we show that tamoxifen(Tam)-induced cytotoxicity is due to the mitochondrial-dependent pathway triggered by the intracellular $Ca^{2+}$ increase in MCF-7 human breast cancer cells. Tam induced the intracellular $Ca^{2+}$ increase. According to the experimental results with $Ca^{2+}$ channel blockers, Tam-induced $Ca^{2+}$ uptake seemed to depend on the voltage-sensitive $Ca^{2+}$ channel at the early stage, but at later stages the intracellular $Ca^{2+}$ increases are more likely due partly to the release of stored $Ca^{2+}$ and partly to the capacitative $Ca^{2+}$ or other entry pathways. Tam-induced $Ca^{2+}$ increase led to the release of cytochrome c from mitochondria into the cytosol and the change of mitochondrial membrane potential. In MCF-7 cells, caspase-7 plays a key role in the downstream of apoptosis because caspase-3 is absent. In the cells treated with Tam, caspase-7 cleavage was increased almost two-fold. There was no marked alteration in the level of anti-apoptotic Bcl-2 protein; however, the cells showed increased expression of pro-apoptotic Bax protein more than two-fold in response to Tam. These results imply that the apoptotic signaling pathway activated by Tam is likely to be mediated via the mitochondrial-dependent pathway.

• Herbal Formula Science
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• v.27 no.4
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• pp.237-244
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• 2019

Objectives : The purpose of this study was to investigate the effects of Carthami flos on pacemaker potentials of small intestinal and colonic Interstitial Cells of Cajal (ICC). Methods : To dissociate the ICC, we used enzymatic digestions from the small intestine and colon in mice. In the ICC, the electrophysiological whole-cell patch-clamp configuration was used to record pacemaker potentials in the cultured ICC. Results : 1. The ICC generated pacemaker potentials in the murine small intestine and colon. 2. Pretreatment with a Ca²⁺ free solution and thapsigargin, a Ca²⁺-ATPase inhibitor in the endoplasmic reticulum, stopped the pacemaker potentials. In the case of Ca²⁺-free solutions, Carthami flos did not induce membrane depolarizations in the murine small intestine and colon. However, when thapsigargin in a bath solution was applied, Carthami flos induced membrane depolarizations only in the murine colon. 3. Pretreatment with 2-APB (transient receptor potential melastatin (TRPM) channel inhibitor) abolished the pacemaker potentials and suppressed Carthami flos-induced effects in the murine small intestine and colon. 4. However, pretreatment with T16Ainh-AO1 (Ca²⁺ activated Cl- channel; anoctamin 1 (ANO1) inhibitor) did not affect the pacemaker potentials and induced Carthami flos-induced effects only in the murine small intestine. Conclusions : These results suggest that Carthami flos can modulate the pacemaker activity of ICC and the mechanisms underlying pacemaking in ICC might be different in the small intestine and the colon.

• Journal of Ginseng Research
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• v.23 no.4
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• pp.235-238
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• 1999

ATP-sensitive $K^+$ channels $(K_{ATP})$ are expressed in vascular smooth muscle cells, skeletal muscle cells, pancreatic ${\beta}$ cells, neurons and epithelial cells. $K_{ATP}$ contributes to regulate membrane potential to control vascular tone, to protect myocardial ischemia, and to regulate insulin secretion in pancreatic ${\beta}$ cells. We previously demonstrated that ginseng saponins and ginsenoside $Rg_3$ activated maxi $Ca^{2+}-activated\;K^+$ channel, and this might cause vasodilation. Because $K_{ATP}$ plays an important roles to regulate the resting membrane potential in vascular smooth muscle cells, we investigated whether ginsenoside $Rg_3$ produces vasodilation by activating $K_{ATP}$ We showed in this study that $K_{ATP}$ is expressed in rabbit coronary artery smooth muscle cells. $K_{ATP}$ was inwardly rectifying and was inhibited by intemal application of ATP. Micromolar minoxidil activated, but glyburide inhibited the activity of $K_{ATP}$ Ginsenoside $Rg_3$ relieved inactivaiton of whole-cell $K_{ATP}$ current without affecting the peak amplitude of $K_{ATP}$ currents presumably due to more opening of the channels.

• The Korean Journal of Physiology and Pharmacology
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• v.11 no.5
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• pp.207-213
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• 2007

This study was designed to characterize ureteral smooth muscle motility and also to study the effect of forskolin(FSK) and isoproterenol(ISO) on smooth muscle contractility in murine ureter. High $K^+$(50 mM) produced tonic contraction by $0.17{\pm}0.06mN$(n=19). Neuropeptide and neurotransmitters such as serotonin($5{\mu}M$), histamine($20{\mu}M$), and carbarchol(CCh, $10{\sim}50{\mu}M$) did not produce significant contraction. However, CCh($50{\mu}M$) produced slow phasic contraction in the presence of 25 mM $K^+$. Cyclopiazonic acid(CPA, $10{\mu}M$), SR $Ca^{2+}$-ATPase blocker, produced tonic contraction(0.07 mN). Meanwhile, inhibition of mitochondria by protonophore carbnylcyanide m-chlorophenylhydrazone(CCCP) also produced weak tonic contraction(0.01 mN). The possible involvement of $K^+$ channels was also pursued. Tetraethyl ammonium chloride(TEA, 10 mM), glibenclamide($10{\mu}M$) and quinidine($20{\mu}M$) which are known to block $Ca^{2+}$-activated $K^+$ channels($K_{Ca}$ channel), ATP-sensitive $K^+$ channels($K_{ATP}$) and nonselective $K^+$ channel, respectively, did not elicit any significant effect. However, $Ba^{2+}$($1{\sim}2mM$), blocker of inward rectifier $K^+$ channels($K_{IR}$ channel), produced phasic contraction in a reversible manner, which was blocked by $1{\mu}M$ nicardipine, a blocker of dehydropyridine-sensitive voltage-dependent L-type $Ca^{2+}$ channels($VDCC_L$) in smooth muscle membrane. This $Ba^{2+}$-induced phasic contraction was significantly enhanced by $10{\mu}M$ cyclopiazonic acid(CPA) in the frequency and amplitude. Finally, regulation of $Ba^{2+}$-induced contraction was studied by FSK and ISO which are known as adenylyl cyclase activator and $\beta$-adrenergic receptor agonist, respectively. These drugs significantly suppressed the frequency and amplitude of $Ba^{2+}$-induced contraction(p<0.05). These results suggest that $Ba^{2+}$ produces phasic contraction in murine ureteral smooth muscle which can be regulated by FSK and $\beta$-adrenergic stimulation.

• Development and Reproduction
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• v.21 no.1
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• pp.11-18
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• 2017

Potassium channels, the largest group of pore proteins, selectively regulate the flow of potassium ($K^+$) ions across cell membranes. The activity and expression of $K^+$ channels are critical for the maintenance of normal functions in vessels and neurons, and for the regulation of cell differentiation and maturation. However, their role and expression in stem cells have been poorly understood. In this study, we isolated perivascular stem cells (PVCs) from human umbilical cords and investigated the expression patterns of big-conductance $Ca^{2+}$-activated $K^+$ ($BK_{Ca}$) and voltage-dependent $K^+$ ($K_v$) channels using the reverse transcription polymerase chain reaction. We also examined the effect of high glucose (HG, 25 mM) on expression levels of $BK_{Ca}$ and $K_v$ channels in PVCs. $K_{Ca}1.1$, $K_{Ca}{\beta}_3$, $K_v1.3$, $K_v3.2$, and $K_v6.1$ were detected in undifferentiated PVCs. In addition, HG treatment increased the amounts of $BK_{Ca}{\beta}_{3a}$, $BK_{Ca}{\beta}_4$, $K_v1.3$, $K_v1.6$, and $K_v6.1$ transcripts. These results suggested that ion channels may have important functions in the growth and differentiation of PVCs, which could be influenced by HG exposure.