• Animal cells and systems
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• v.14 no.2
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• pp.91-98
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• 2010

Male rats were given a single injection of iron, and temporal changes in iron content and iron-induced effects were examined in heart cellular fractions. Over a period of 72 h, the contents of total and labile iron, reactive oxygen species, and NO in tissue homogenate, nuclear debris, and postmitochondrial fractions were mostly constant, but in mitochondria they continuously increased. An abrupt decrease in membrane potential and NAD(P)H at 12 h was also found in mitochondria. The respiratory control ratio was reduced slowly with a slight recovery at 72 h, suggesting uncoupling by iron.While the ATP content of tissue homogenate decreased steadily until 72 h, it showed a prominent increase in mitochondria at 12 h. Total iron and calcium concentration also progressively increased in mitochondria over 72 h. Enzyme activity of the oxidative phosphorylation system was significantly altered by iron injection: activities of complexes I, III, and IV were reduced considerably, but complex II activity and the ATPase activity of complex V were enhanced. A reversal of activity in complexes I and II at 12 h suggested reverse electron transfer due to iron overload. These results support the argument that mitochondrial activities including oxidative phosphorylation are modulated by excessive iron.

• The Korean Journal of Physiology
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• v.22 no.1
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• pp.55-62
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• 1988

가토 신피질 절편에서 p-aminohippurate (PAH) 이동에 대한 카드뮴 이온(Cd)의 영향을 조사하여 다음과 같은 결과를 얻었다. 조직절편과 용액내의 PAH 농도비(S/M PAH)는 용액내에 Cd이 0.1 mM이상 존재할 때에 현저히 감소되었다. PAH influx에 대한 동력학적 분석결과 Cd에 의하여 influx의 최대이동율(즉 $V_{max}$)은 심하게 감소되지만 운반체와 기질간의 친화력(즉 $K_{m}$)에는 변화가 없었으며, 수동적 influx 역시 변화되지 않았다. 신피질조직의 산소 소모율은 1 mM Cd에 의하여 35% 가량 억제되었으며, 신피질 microsome 분획의 Na-K-ATPase 활성도는 Cd 농도가 $10^{-7}M$ 이상일 때 의의있게 억제되었다. 이상의 결과로 미루어 볼 때 신장조직이 카드뮴이온에 직접 노출될 경우 유기음이온의 능동적 이동능이 심하게 저해된다고 사료된다.

• Molecules and Cells
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• v.46 no.11
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• pp.655-663
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• 2023

Autophagy dysfunction is associated with human diseases and conditions including neurodegenerative diseases, metabolic issues, and chronic infections. Additionally, the decline in autophagic activity contributes to tissue and organ dysfunction and aging-related diseases. Several factors, such as down-regulation of autophagy components and activators, oxidative damage, microinflammation, and impaired autophagy flux, are linked to autophagy decline. An autophagy flux impairment (AFI) has been implicated in neurological disorders and in certain other pathological conditions. Here, to enhance our understanding of AFI, we conducted a comprehensive literature review of findings derived from two well-studied cellular stress models: glucose deprivation and replicative senescence. Glucose deprivation is a condition in which cells heavily rely on oxidative phosphorylation for ATP generation. Autophagy is activated, but its flux is hindered at the autolysis step, primarily due to an impairment of lysosomal acidity. Cells undergoing replicative senescence also experience AFI, which is also known to be caused by lysosomal acidity failure. Both glucose deprivation and replicative senescence elevate levels of reactive oxygen species (ROS), affecting lysosomal acidification. Mitochondrial alterations play a crucial role in elevating ROS generation and reducing lysosomal acidity, highlighting their association with autophagy dysfunction and disease conditions. This paper delves into the underlying molecular and cellular pathways of AFI in glucose-deprived cells, providing insights into potential strategies for managing AFI that is driven by lysosomal acidity failure. Furthermore, the investigation on the roles of mitochondrial dysfunction sheds light on the potential effectiveness of modulating mitochondrial function to overcome AFI, offering new possibilities for therapeutic interventions.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.25-25
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• 2002

CodWX, encoded by the cod operon in Bacillus subtilis, is a member of the ATP-dependent protease complex family, and is homologous to the eukaryotic 26S proteasome. It consists of two multimeric complexes: two hexameric ATPase caps of CodX and a protease chamber consisting of CodW dodecamer. Prior structural studies have shown that the N-terminal threonine residue is solely functional as a proteolytic nucleophile in ATP-dependent proteases such as HslV and certain β-type subunits of 20S proteasome, which have a primary sequence similarity of -50% and -20% with CodW respectively. Here we present a 3.0 Å resolution crystal structure of CodW, which is the first N-terminal serine protease among the known proteolytic enzymes. In spite of the same fold and the conserved contacts between subunits with HslV in E. coli and H. influenza, this structure shows the five additional residues extending from conserved Thr1 among the other ATP-dependent pretense and extraordinary basic proteolytic chamber.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.5
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• pp.275-282
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• 2005

By using differential display, we identified one of the genes encoding the multi-subunit complex protein V-ATPase, c subunit gene (ATP6L), and showed alterations of the gene expression by oxidative stresses. Expression of the ATP6L gene in Neuro-2A cells was increased by the treatment with $H_2O_2$ and incubation in hypoxic chamber, implying that the expression of the ATP6L gene is regulated by oxidative stresses. To examine mechanisms involved in the regulation of the gene expression by oxidative stresses, the transcriptional activity of the rat ATP6L promoter was studied. Transcription initiation site was determined by primer extension analysis and DNA sequencing, and promoter of the rat ATP6L and its deletion clones were constructed in reporter assay vector. Significant changes of the promoter activities in Neuro-2A cells were observed in two regions within the proximal 1 kbp promoter, and one containing a suppressor was in -195 to -220, which contains GC box that is activated by binding of Sp1 protein. The suppression of promoter activity was lost in mutants of the GC box. We confirmed by electrophoretic mobility shift and supershift assays that Sp1 protein specifically binds to the GC box. The promoter activity was not changed by the $H_2O_2$ treatment and incubation in hypoxic chamber, however, $H_2O_2$ increased the stability of ATP6L mRNA. These data suggest that the expression of the ATP6L gene by oxidative stresses is regulated at posttranscriptional level, whereas the GC box is important in basal activities of the promoter.

• Journal of Pharmacopuncture
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• v.19 no.2
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• pp.137-144
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• 2016

Objectives: Several studies have revealed that systemic hypertension is strongly associated with cataractogenesis. However, the pathophysiology and treatment is often unclear. In this study, we evaluated the anti-cataractogenic effect of cinnamaldehyde (CA), a natural organic compound, in rats with fructose-induced hypertension. Methods: The rats were divided into six groups. For six weeks, the normal group received a suspension of 0.5% carboxy methyl cellulose (10 mL/kg/day, p.o.) while five other groups received a 10% (w/v) fructose solution in their drinking water to induce hypertension. By the end of the third week hypertension had been induced in all the animals receiving fructose. From the beginning of the fourth week to the end of the sixth week, one of those five groups (control) continued to receive only 10% (w/v) fructose solution, one group (standard) received ramipril (1 mg/kg/day, p.o.) plus 10% (w/v) fructose solution, and three groups (experimental) received CA at doses of 20, 30, and 40 mg/kg/day p.o., plus 10% (w/v) fructose solution. Blood pressure was measured weekly using a non-invasive blood pressure apparatus. After six weeks, the animals were sacrificed, and the anti-cataractogenic effects on the eye lenses were evaluated. Results: Administration of fructose elevated both the systolic and the diastolic blood pressures, which were significantly reduced by CA at all dose levels. In the control group, a significant increase in the malonaldehyde (MDA) level and decreases in the total protein, $Ca^{2+}$adenosine triphosphate (ATP)ase activity, glutathione peroxidase, catalase, superoxide dismutase and glutathione levels, as compared to the normal group, were observed. Administration of CA at all doses significantly restored the enzymatic, non-enzymatic, antioxidants, total protein, and $Ca^{2+}$ATPase levels, but decreased the MDA level, as compared to the control group. Conclusion: The present study revealed that CA modulated the antioxidant parameters of the serum and lens homogenates in hypertension-induced cataractogenic animals.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2005.06a
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• pp.154-164
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• 2005

Saccharomyces cerevisiae KNU5377 is a thermotolerant strain, which can ferment ethanol from wasted papers and starch at 40$^{\circ}C$ with the almost same rate as at 30$^{\circ}C$. This strain showed alcohol fermentation ability to convert wasted papers 200 g (w/v) to ethanol 8.4% (v/v) at 40$^{\circ}C$, meaning that 8.4% ethanol is acceptable enough to ferment in the industrial economy. As well, all kinds of starch that are using in the industry were converted into ethanol at 40$^{\circ}C$ with the almost same rate as at 30$^{\circ}C$. Hyperthermic cell killing kinetics and differential scanning calorimetry (DSC) revealed that exponentially growing cells of this yeast strain KNU5377 were more thermotolerant than those of S. cerevisiae ATCC24858 used as a control. This intrinsic thermotolernace did not result from the stability of entire cellular components but possibly from that of a particular target. Heat shock induced similar results in whole cell DSC profiles of both strains and the accumulation of trehalose in the cells of both strains, but the trehalose contents in the strain KNU5377 were 2.6 fold higher than that in the control strain. On the contrary to the trehalose level, the neutral trehalase activity in the KNU5377 cells was not changed after the heat shock. This result made a conclusion that though the trehalose may stabilize cellular components, the surplus of trehalose in KNU5377 strain was not essential for stabilization of whole cellular components. A constitutively thermotolerant yeast, S. cerevisiae KNU5377, was compared with a relatively thermosensitive control, S. cerevisiae ATCC24858, by assaying the fluidity and proton ATPase on the plasma membrane. Anisotropic values (r) of both strains were slightly increased by elevating the incubation temperatures from 25$^{\circ}C$ to 37$^{\circ}C$ when they were aerobically cultured for 12 hours in the YPD media, implying the membrane fluidity was decreased. While the temperature was elevated up to 40$^{\circ}C$, the fluidity was not changed in the KNU5377 cell, but rather increased in the control. This result implies that the plasma membrane of the KNU5377 cell can be characterized into the more stabilized state than control. Besides, heat shock decreased the fluidity in the control strain, but not in the KNU5377 strain. This means also there's a stabilization of the plasma membrane in the KNU5377 cell. Furthermore, the proton ATPase assay indicated the KNU5377 cell kept a relatively more stabilized glucose metabolism at high temperature than the control cell. Therefore, the results were concluded that the stabilization of plasma membrane and growth at high temperature for the KNU5377 cell. Genome wide transcription analysis showed that the heat shock responses were very complex and combinatory in the KNU5377 cell. Induced by the heat shock, a number of genes were related with the ubiquitin mediated proteolysis, metallothionein (prevent ROS production from copper), hsp27 (88-fold induced remarkably, preventing the protein aggregation and denaturation), oxidative stress response (to remove the hydrogen peroxide), and etc.

• Molecules and Cells
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• v.27 no.5
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• pp.525-531
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• 2009

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and $Ca^{2+}$-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of -70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic $M_3$ receptor antagonist, but not by methotramine, a muscarinic $M_2$ receptor antagonist. Intracellular $GDP-{\beta}-S$ suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external $Na^+$-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a $Ca^{2+}$-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external $Ca^{2+}$. In recording of intracellular $Ca^{2+}$ concentrations using fluo 3-AM dye, carbachol increased intracellular $Ca^{2+}$ concentrations with increasing of $Ca^{2+}$ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic $M_3$ receptors by a G-protein dependent intracellular $Ca^{2+}$ release mechanism.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.5
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• pp.529-538
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• 1999

This study was undertaken to examine the effect of ethanol on $Na^+ -dependent$ phosphate $(Na^+-P_i)$ uptake in opossum kidney (OK) cells, an established renal proximal tubular cell line. Ethanol inhibited ^Na^+-dependent$ component of phosphate uptake in a dose-dependent manner with $I_{50}$ of 8.4%, but it did not affect $Na^+-independent$ component. Similarly, ethanol inhibited $Na^+-dependent$ uptakes of glucose and amino acids (AIB, glycine, alanine, and leucine). Microsomal $Na^+-K^+-ATPase$ activity was not significantly altered when cells were treated with 8% ethanol. Kinetic analysis showed that ethanol increased $K_m$ without a change in $V_{max}$ of $Na^+-P_i$ uptake. Inhibitory effect of n-alcohols on $Na^+-P_i$ uptake was dependent on the length of the hydrocarbon chain, and it resulted from the binding of one molecule of alcohol, as indicated by the Hill coefficient (n) of 0.8-1.04. Catalase significantly prevented the inhibition, but superoxide dismutase and hydroxyl radical scavengers did not alter the ethanol effect. A potent antioxidant DPPD and iron chelators did not prevent the inhibition. Pyrazole, an inhibitor of alcohol dehydrogenase, did not attenuate ethanol-induced inhibition of $Na^+-P_i$ uptake, but it prevented ethanol-induced cell death. These results suggest that ethanol may inhibit $Na^+-P_i$ uptake through a direct action on the carrier protein, although the transport system is affected by alterations in the lipid environment of the membrane.

• Neonatal Medicine
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• v.28 no.3
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• pp.133-138
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• 2021

Osteopetrosis refers to a group of genetic skeletal disorders characterized by osteosclerosis and fragile bones. Osteopetrosis can be classified into autosomal dominant, autosomal recessive, or X-linked forms, which might differ in clinical characteristics and disease severity. Autosomal recessive osteopetrosis, also known as malignant osteopetrosis, has an earlier onset, more serious clinical symptoms, and is usually fatal. We encountered a 1-day-old girl who was born full-term via vaginal delivery, which was complicated by meconium-stained amniotic fluid, cephalo-pelvic disproportion, and nuchal cord. Routine neonatal care was provided, in addition to blood tests and chest radiography to screen for sepsis, as well as skull radiography to rule out head injuries. Initial blood tests revealed hypocalcemia, which persisted on follow-up tests the next day. Radiographic examinations revealed diffusely increased bone density and a "space alien" appearance of the skull. Based on radiographic and laboratory findings, the infantile form of osteopetrosis was suspected and genetic testing for identification of the responsible gene. Eventually, a heterozygous mutation of the T cell immune regulator 1, ATPase H+ transporting V0 subunit a3 (TCIRG1) gene (c.292C>T) was identified, making this the first reported case of neonatal-onset malignant osteopetrosis with TCIRG1 mutation in South Korea. Early-onset hypocalcemia is common and usually results from prematurity, fetal growth restriction, maternal diabetes, perinatal asphyxia, and physiologic hypoparathyroidism. However, if hypocalcemia persists, we recommend considering 'infantile of osteopetrosis' as a rare cause of neonatal hypocalcemia and performing radiographic examinations to establish the diagnosis.