Publications by authors named "Kee-Hyun Choi"

Monoamine transporters, including dopamine, norepinephrine, and serotonin transporters (DAT, NET, and SERT, respectively), are important therapeutic targets due to their essential roles in the brain. To overcome the slow action of selective monoamine reuptake inhibitors, dual- or triple-acting inhibitors have been developed. Here, to examine whether combination treatments of selective reuptake inhibitors have synergistic effects, the pharmacological properties of DAT, NET, and SERT were investigated using the selective inhibitors of each transporter, which are vanoxerine, nisoxetine, and fluoxetine, respectively.

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CLC proteins are a ubiquitously expressed family of chloride-selective ion channels and transporters. A dearth of pharmacological tools for modulating CLC gating and ion conduction limits investigations aimed at understanding CLC structure/function and physiology. Herein, we describe the design, synthesis, and evaluation of a collection of -arylated benzimidazole derivatives (BIMs), one of which (BIM1) shows unparalleled (>20-fold) selectivity for CLC-Ka over CLC-Kb, the two most closely related human CLC homologs.

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Glioblastoma is the most common and aggressive primary malignant brain tumor. Temozolomide (TMZ), a chemotherapeutic agent combined with radiation therapy, is used as a standard treatment. The infiltrative nature of glioblastoma, however, interrupts effective treatment with TMZ and increases the tendency to relapse.

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Cooperative gating between ion channels, i.e. the gating of one channel directly coupled to the gating of neighboring channels, has been observed in diverse channel types at the single-channel level.

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Introduction: Neuronal T-type calcium channels (T-type channels) are expressed throughout the central nervous system (CNS), regulating neuronal excitability. T-type channels in the CNS are involved in various neurophysiological and pathophysiological states, and thus have become a promising therapeutic target.

Areas Covered: This article discusses T-type channel-related CNS disorders such as epilepsy, neuropathic pain, insomnia and tremor disorders including Parkinson's disease.

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The lack of small-molecule inhibitors for anion-selective transporters and channels has impeded our understanding of the complex mechanisms that underlie ion passage. The ubiquitous CLC "Chloride Channel" family represents a unique target for biophysical and biochemical studies because its distinctive protein fold supports both passive chloride channels and secondary-active chloride-proton transporters. Here, we describe the synthesis and characterization of a specific small-molecule inhibitor directed against a CLC antiporter (ClC-ec1).

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In small cells containing small numbers of ion channels, noise due to stochastic channel opening and closing can introduce a substantial level of variability into the cell's membrane potential. Negatively cooperative interactions that couple a channel's gating conformational change to the conformation of its neighbor(s) provide a potential mechanism for mitigating this variability, but such interactions have not previously been directly observed. Here we show that heterologously expressed ATP-sensitive potassium channels generate noise (i.

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T-type calcium channels are involved in a variety of physiological and pathophysiological processes, and thus could be therapeutic targets. However, there is no T-type channel selective blocker for use in clinical practice, demanding a need for the development of novel drugs where a higher-throughput screening system is required. Here we present pharmacological studies on Ca(v)3.

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The human ether-à-go-go related gene potassium channel is a key player in cardiac rhythm regulation, thus being an important subject for a cardiac toxicity test. Ever since human ether-à-go-go related gene channel inhibition-related cardiac arrest was proven to be fatal, numerous numbers of data on human ether-à-go-go related gene channel inhibition have been piled up. However, there has been no quantitative study on human ether-à-go-go related gene channel inhibition by quaternary ammonium derivatives, well-known potassium channel blockers.

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Low voltage-activated T-type calcium channels are involved in the regulation of the neuronal excitability, and could be subject to many antipsychotic drugs. The effects of clozapine, an atypical antipsychotic drug, on recombinant Ca(v)3.1 T-type calcium channels heterologously expressed in human embryonic kidney 293 cells were examined using whole-cell patch-clamp recordings.

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In pancreatic beta cells, insulin secretion is tightly controlled by the cells' metabolic state via the ATP-sensitive potassium (KATP) channel. ATP is a key mediator in this signaling process, where its role as an inhibitor of KATP channels has been extensively studied. Since the channel contains an ATPase as an accessory subunit, the possibility that ATP hydrolysis mediates KATP channel opening has also been proposed.

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Processive proteases can unfold proteins and cleave them into fragments of a characteristic size. The detailed mechanism by which product sizes are controlled is still in question. One possible mechanism for the control of product sizes would be translocation of unfolded polypeptides to the protease active sites in units of defined length.

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