• BMB Reports
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• 제39권1호
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• pp.91-96
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• 2006

Previously, we have shown that nitric oxide (NO) directly activates the Maxi-K channels. In the present study, we have investigated whether NO has prolonged effects on the Maxi-K channels reconstituted in lipid bilayer. Application of S-nitroso-N-acetyl-D, L-penicillamine (SNAP), a NO donor, induced an immediate increase of open probability (Po) of Maxi-K channel in a dose-dependent manner. When SNAP was removed from the cytosolic solution, the Po did not simply returned to, but irreversibly decreased to a level lower than that of the control Po. At 0.2 mM, (Z)-[N-(3-Ammoniopropyl)-N-(n-propyl)amino] diazen-1-ium-1,2-diolate (PAPA-NO), another NO donor, produced a similar increase of Po and decrease of Po upon washout. The increasing effects of SNAP on Po were not blocked by either 50 U/ml superoxide dismutase (SOD) or 2 mM N-ethylmaleimide (NEM) pre-treatments. However, NEM appears to be ineffective when applied after SNAP. These results suggest that NO can modulate Maxi-K channel via direct interaction and chemical modification, such as S-nitrosylation in the brain.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.645-645
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• 2013

Applying a first-principles computational approach combining density-functional theory and matrix Green's function calculations, we have studied the effects [2+2] cycloaddition olligormerization of fullerene $C_{60}$ chains on their junction charge transport properties. Analyzing first the microscopic mechanism of the switching realized in recent scanning tunneling microscope (STM) experiments, we found that, in agreement with experimental conclusions, the device characteristics are not significantly affected by the changes in electronic structure of $C_{60}$ chains. It is further predicted that the switching characteristics will sensitively depend on the STM tip metal species and the associated energy level bending direction in the $C_{60}-STM$ tip vacuum gap. Considering infinite $C_{60}$ chains, however, we confirm that unbound $C_{60}$ chains with strong orbital hybridizations and band formation should in principle induce a much higher conductance state. We demonstrate that a nanoelectromechanical approach in which the $C_{60}-STM$ tip distance is maintained at short distances can achieve a metal-independent and drastically improved switching performance based on the intrinsically better electronic connectivity in the bound $C_{60}$ chains.

• BMB Reports
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• 제49권10호
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• pp.542-547
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• 2016

Acid-sensing ion channels (ASICs) are proton-gated cation channels widely expressed in the nervous system. Proton sensing by ASICs has been known to mediate pain, mechanosensation, taste transduction, learning and memory, and fear. In this study, we investigated the differential subcellular localization of ASIC2a and ASIC3 in heterologous expression systems. While ASIC2a targeted the cell surface itself, ASIC3 was mostly accumulated in the ER with partial expression in the plasma membrane. However, when ASIC3 was co-expressed with ASIC2a, its surface expression was markedly increased. By using bimolecular fluorescence complementation (BiFC) assay, we confirmed the heteromeric association between ASIC2a and ASIC3 subunits. In addition, we observed that the ASIC2a-dependent surface trafficking of ASIC3 remarkably enhanced the sustained component of the currents. Our study demonstrates that ASIC2a can increase the membrane conductance sensitivity to protons by facilitating the surface expression of ASIC3 through herteromeric assembly.

• 한국수산과학회지
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• 제54권5호
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• pp.676-684
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• 2021

Euryhaline teleost have extraordinary ability to deal with a wide range of salinity changes. To study the seawater adaptability of rainbow trout Oncorhynchus mykiss (body weight 638±54 g, length 38.6±2 cm) to salinity increase fish were transferred from freshwater to 7, 14, 21, 28 and 32 psu and checked for mortality over 5 days. No mortality was observed in 0-32 psu. In fish transferred to 0-32 psu, blood osmolality was maintained within physiological range. The changes of serum enzyme activities (aspartate transaminase, AST and alanine transaminase, ALT) showed no significant level during experimental period. To explore the underlying molecular physiology of gill and kidney responsible for body fluid regulation, we measured mRNA expression of five genes, Na⁺/K⁺/2Cl^- cotransporter1 (NKCC1), aquaporin3 (AQP3), cystic fibrosis transmembrane conductance regulator (CFTR), glucocorticoid receptor (GR) and growth hormone receptor (GHR) in response to salt stress. Based on our result, rainbow trout could tolerate gradual transfer up to 32 psu for 5 days without mortality under physiological stress. This study suggests to alleviate osmotic stress to fish, a gradually acclimation to increasing salinity is recommended.

• BMB Reports
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• 제53권9호
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• pp.484-489
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• 2020

Epilepsy is a neurological disorder characterized by unpredictable seizures, which are bursts of electrical activity that temporarily affect the brain. Cereblon (CRBN), a DCAFs (DDB1 and CUL4-associated factors), is a well-established protein associated with human mental retardation. Being a substrate receptor of the cullin-RING E3 ubiquitin ligase (CRL) 4 complex, CRBN mediates ubiquitination of several substrates and conducts multiple biological processes. In the central nervous system, the large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel, which is the substrate of CRBN, is an important regulator of epilepsy. Despite the functional role and importance of CRBN in the brain, direct injection of pentylenetetrazole (PTZ) to induce seizures in CRBN knock-out mice has not been challenged. In this study, we investigated the effect of PTZ in CRBN knock-out mice. Here, we demonstrate that, compared with WT mice, CRBN knock-out mice do not show the intensification of seizures by PTZ induction. Moreover, electroencephalography recordings were also performed in the brains of both WT and CRBN knockout mice to identify the absence of significant differences in the pattern of seizure activities. Consistently, immunoblot analysis for validating the protein level of the CRL4 complex containing CRBN (CRL4^Crbn) in the mouse brain was carried out. Taken together, we found that the deficiency of CRBN does not affect PTZ-induced seizure.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 추계학술발표회 초록집
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• pp.35-35
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• 2001

agnesium Oxide (MgO) with a NaCI structure is well known to exhibit high secondary electron emission, excellent high temperature chemical stability, high thermal conductance and electrical insulating properties. For these reason MgO films have been widely used for a buffer layer of high $T_c$ superconducting and a protective layer for AC-plasma display panels to improve discharge characteristics and panel lifetime. Up to now MgO films have been synthesized by lE-beam evaporation, Molecular Beam Epitaxy (MBE) and Metalorganic Chemical Vapor Deposition (MOCVD), however there have been some limitations such as low film density and micro-cracks in films. Therefore magnetron sputtering process were emerged as predominant method to synthesis high density MgO films. In previous works, we designed and manufactured unbalanced magnetron source with high power density for the deposition of high quality MgO films. The magnetron discharges were sustained at the pressure of O.lmtorr with power density of $110W/\textrm{cm}^2$ and the maximum deposition rate was measured at $2.8\mu\textrm{m}/min$ for Cu films. In this study, the syntheses of MgO films were carried out by unbalanced magnetron sputtering with various $O_2$ partial pressure and specially target power densities, duty cycles and frequency using pulsed DC power supply. And also we investigated the plasma states with various $O_2$ partial pressure and pulsed DC conditions by Optical Emission Spectroscopy (OES). In order to confirm the relationships between plasma states and film properties such as microstructure and secondary electron emission coefficient were analyzed by X-Ray Diffraction(XRD), Transmission Electron Microscopy(TEM) and ${\gamma}-Focused$ Ion Beam (${\gamma}-FIB$).

• The Korean Journal of Physiology and Pharmacology
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• 제6권5호
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• pp.247-253
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• 2002

Major pelvic ganglia (MPG) neurons are classified into sympathetic and parasympathetic neurons according to the electrophysiological properties; membrane capacitance (Cm), expression of T-type $Ca^{2+}$ channels, and the firing patterns during depolarization. In the present study, function and molecular expression of ATP-sensitive $K^+\;(K_{ATP})$ channels was investigated in MPG neurons of male rats. Only in parasympathetic MPG neurons showing phasic firing patterns, hyperpolarizing changes were elicited by the application of diazoxide, an activator of $K_{ATP}$ channels. Glibenclamide $(10{\mu}M),$ a $K_{ATP}$ channel blocker, completely abolished the diazoxide-induced hyperpolarization. Diazoxide increased inward currents at high $K^+$ (90 mM) external solution, which was also blocked by glibenclamide. The metabolic inhibition by the treatment with mitochondrial respiratory chain inhibitors (rotenone and antimycin) hyperpolarized the resting membrane potential of parasympathetic neurons, which was not observed in sympathetic neurons. The hyperpolarizing response to metabolic inhibition was partially blocked by glibenclamide. RT-PCR analysis revealed that MPG neurons mainly expressed the $K_{ATP}$ channel subunits of Kir6.2 and SUR1. Our results suggest that MPG neurons have $K_{ATP}$ channels, mainly formed by Kir6.2 and SUR1, with phenotype-specificity, and that the conductance through this channel in parasympathetic neurons may contribute to the changes in excitability during hypoxia and/or metabolic inhibition.

• Molecules and Cells
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• 제39권7호
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• pp.530-535
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• 2016

Large conductance calcium-activated potassium (BK) channels participate in many important physiological functions in excitable tissues such as neurons, cardiac and smooth muscles, whereas the knowledge of BK channels in bone tissues and osteoblasts remains elusive. To investigate the role of BK channels in osteoblasts, we used transcription activator-like effector nuclease (TALEN) to establish a BK knockout cell line on rat ROS17/2.8 osteoblast, and detected the proliferation and mineralization of the BK-knockout cells. Our study found that the BKknockout cells significantly decreased the ability of proliferation and mineralization as osteoblasts, compared to the wild type cells. The overall expression of osteoblast differentiation marker genes in the BK-knockout cells was significantly lower than that in wild type osteoblast cells. The BK-knockout osteoblast cell line in our study displays a phenotype decrease in osteoblast function which can mimic the pathological state of osteoblast and thus provide a working cell line as a tool for study of osteoblast function and bone related diseases.

• 한국산학기술학회논문지
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• 제16권3호
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• pp.1964-1971
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• 2015

사람의 골수 또는 제대정맥에서 유래된 중간엽 줄기 세포 (hBM-MSC 또는 hUC-MSC)는 임상적 치료 적용에 매우 유용한 세포유형으로 알려져 왔다. 우리는 이러한 세포에서 two-pore 도메인 포타슘 (K2P)채널을 조사하였다. K2P 채널은 다양한 세포유형들에서 안정막 전위를 형성하는데 중요한 역할을 한다. 그들 중 TREK1은 수소, 저산소증, 다불포화 지방산, 항우울제 및 신경전달물질들의 표적이다. 우리는 RT-PCR 분석과 팻취고정기법을 이용하여 hBM-MSCs와 hUC-MSC가 기능적인 TREK1 채널을 발현하는지 조사했다. hBM-MSCs와 hUC-MSCs에서 100 pS 단일 채널 전도도를 가진 포타슘채널이 발견되었고, 그 채널은 세포막 신전 (-5 mmHg ~ -15 mmHg), 아라키도닉산 ($10{\mu}M$), 세포내 산성화 (pH 6.0)에 의해 활성화 되었다. 이러한 전기생리학적 성질은 TREK1과 유사하였다. 우리의 결과는 안정막 전위에 기여하는 TREK1 채널이 hBM-MSC와 hUC-MSC에 기능적으로 존재하고 있음을 제시한다.

• 생명과학회지
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• 제19권10호
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• pp.1484-1488
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• 2009

가족성 저칼륨성 주기성 마비란 상염색체 우성 유전 질환으로 저칼륨혈증을 동반한 간헐적인 가역적 이완성 근육 마비를 특징으로 한다. 세포내 저류된 칼륨으로 인해 저칼륨혈증이 지속되고 근세포 활성이상으로 인해 마비가 발생하는 것으로 알려져 있다. 이러한 증상발현의 분자생물학적 기전을 확인하기 위해 세포 내 칼륨이온을 세포 밖으로 이동시키는 지연성 정류형 채널 단백질의 일종인 KCNQ3와 KCNQ5를 대상으로, 정상인과 환자에서 채취한 골격근 세포를 생리적 세포외 정상 칼륨농도인 4 mM과 탈분극 유도를 위한 고칼륨농도인 50mM에 노출시켜 단백질의 양적 변화 유무를 확인하였다. 유전자 발현양상을 확인하기 위해 mRNA의 양적 변화를 확인한 결과 모든 조건에서 유의한 변화가 관찰되지 않아 정상 칼륨조건과 고칼륨조건이 두 유전자발현의 변화를 야기하지 않음을 확인하였다. 그러나 단백질 양을 관찰한 결과 환자의 골격근 세포가 50 mM의 칼륨농도에 노출되는 경우 KCNQ3 단백질은 세포질 내에서 증가하고 세포막 내에서 감소하였다. 이는 환자의 골격근 세포가 고농도의 세포외 칼륨에 의해 탈분극 되는 경우 재분극에 중요한 기능을 담당하는 KCNQ3 채널 단백질이 세포질 내로 이동하여 재분극 형성의 장애를 초래하고 이로 인해 근세포 활성이 일어나지 않게 되어 마비를 유발할 수 있음을 시사하는 결과로 본 질환의 새로운 발병 기전을 설명할 수 있는 근거로 생각된다.