• The Korean Journal of Zoology
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• v.38 no.2
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• pp.167-176
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• 1995

Glucose-regulated proteins (grp's), srp94 3nd grp78/BiP, are a group of stress proteins which are highly synthesized in cells exposed to a variety of stressful agents including tunicamycin 3nd Ca2+ ionophore. Grp78/BiP is hon to function as a molecular chaperone which regulates the folding and assembly of secretory or membrane proteins, but the biological function of grp941 remains to be elucidated. In this study, we have examined the intracellular distribution of grV's and the function of srp94. Grp's are resident in the endoplasmic reticulum (ERI 3nd a specific sequence (Lys-Asp-Glu-Leu) at their C-terminus is known to be responsible for their retention within the ER. However, it has been unclear whether upon disturbance of cellular Caa+ homeostasis by the Ca2+ ionophore, grp94 is retained within the ER or secreted into the medium. In this study, we showed that in the presence of C3a+ ionophore, grp94 and gif78/BiP are present in the cells, mainly within the ER. We have also investigated whether grp94 might function as a molecular chaperone. Here we showed that in the immunoglobulin (Ig)-secreting hvbridom3 cells, grp94 transientlY interacts with fully glycosylated Is heavy chain, suggesting that grpg94 may be involved in facilitating the folding and assembly of Ig heavy chains.

• Animal cells and systems
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• v.7 no.3
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• pp.265-269
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• 2003

Vascular endothelial growth factor (VEGF) is a potent regulator of normal and abnormal angiogenesis. Recent literature suggests that VEGF has several activities that may amplify acute inflammation reactions. Dysregulated VEGF expression has been implicated as a major contributor to the development of a number of common disease pathologies. One of common mutations in the 3'- untranslated region of the VEGF gene, a C\longrightarrowT exchange at nucleotide position 936, has been found to be significantly associated with VEGF expression levels in the plasma from a previous Austrian study. The frequency of this mutation could be important genetic information regarding tumor growth and angiogenesis related diseases. The aim of this study was to investigate the frequency distribution of this mutation in general Korean population. We examined the statistical data from 207 healthy Korean subjects. Observed numbers (%) of 936T were 28.5 (CT) and 3.9 (TT), respectively. The mutant allele frequency of 936T in Korean subjects was 0.18, which appeared somewhat higher than that in Austrian subjects.

• The Journal of Korean Medicine
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• v.20 no.3 s.39
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• pp.18-26
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• 1999

This paper aims to determine the effect of CBW on the liver of mice treated with PQ (paraquat) examined by light and transmission electron microscope. Under light microscopic observations, the 2 days control showed mild congestion and necrosis of liver while those were manifest in the 7 days control. When electron microscopy was used, mitochondria and rough endoplasmic reticulum were dilated or destructed in the 2 days control and 7 days control, respectively. Under light microscopic observations, the 2 days experimental group did not show any hepatic damages while accumulation of glycogen granules in the cytoplasm was conspicuous in the 7 days experimental group. When electron microscopy was used, mitochondria and rough endoplasmic reticulum were less dilated in the 2 days experirrlental group. On the other hand, denaturation of cell organelles was not observed in the 7 days experimental group. These results suggest that CBW seems related with recovery from the PQ cytotoxity.

• Journal of Microbiology and Biotechnology
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• v.16 no.9
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• pp.1453-1458
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• 2006

PKR-like endoplasmic reticulum (ER) kinase (PERK) is a type I transmembrane ER-resident protein containing a cytoplasmic catalytic domain with a Ser/Thr kinase activity, which is most closely related to the eukaryotic translation initiation factor-$2{\alpha}$ ($eIF2{\alpha}$) kinase PKR involved in the antiviral defense pathway by interferon. We cloned and expressed the PERK C-terminal kinase domain (cPERK) in Escherichia coli. Like PERK activation in cells under ER stress, wild-type cPERK underwent autophosphorylation when overexpressed in E. coli, whereas the cPERK(K621M) with a methionine substitution for the lysine at amino acid 621 lost the autophosphorylation activity. The activated form cPERK which was purified to near homogeneity, formed an oligomer and was able to trans-phosphorylate specifically its cellular substrate $eIF2{\alpha}$. Two-dimensional phosphoamino acids analysis revealed that phosphorylation of cPERK occurs at the Ser and Thr residues. The functionally active recombinant cPERK, and its inactive mutant should be useful for the analysis of biochemical functions of PERK and for the determination of their three-dimensional structures.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.19-19
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• 2003

We have developed a cardiac cell model (Kyoto Model) for the sinoatrial node and ventricle, which is composed of a common set of kinetic equations of membrane ionic currents, Ca$\^$2+/dynamics of sarcoplasmic reticulum and contractile protein. To expand this model by including metabolic pathways, the intracellular ATP metabolism, which is pivotal in cardiac excitation - contraction coupling, was incorporated. ATP consumption by the sarcolemmal Na$\^$+/ pump and the Ca pump in the sarcoplasmic reticulum were calculated with stoichiometry of 3Na:2K:1ATP and 2Ca:1ATP, respectively. ATP consumption by contraction was estimated according to experimental data. Dependence of contraction on ATP and inorganic phosphate was modeled, based on data of skinned cardiac fiber. in production by mitochondrial oxidative phosphorylation was modified from Korzeniewski '||'&'||' Zoladz (2001), and creatine kinase and adenylate kinase reactions were incorporated. ATP dependence of ATP-sensitive K channel and L type Ca channel were also included.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.53-53
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• 2003

Calumenin was previously identified as a high affinity Ca$\^$2+/ binding protein in mouse cardiac sarcoplasmic reticulum (SR). For the present study, a 48 kDa skeletal homologue of calumenin was identified by sucrose-density gradient of rabbit skeletal SR membranes, concanavalin A treatment, 2D-gel electrophoresis, $\^$45/Ca$\^$2+/ overlay, Stains-all staining, and MALDI-TOF analysis. We attempted to clone the skeletal calumenin by RT-PCR based on mouse cardiac and human calumenin sequences. The deduced amino acid sequence (315 residues) of the skeletal calumenin showed high identity to mouse cardiac calumenin (90％). As seen in the cardiac calumenin, the deduced sequence contains a 19 amino acid N-terminal signal sequence and a HDEF C-terminal sequence, a putative retrieval signal to ER. Also, the skeletal calumenin contains one N-glycosylation site, three PKC phosphorylation sites, eight casein kinase 2 phosphorylation sites, and 6 EF-hand domains. GST-calumenin showed a conformational change and increased mobility in the presence of Ca$\^$2+/ in SDS-PAGE. Three calumenin interacting proteins (ryanodine receptor 1, glycogen phosphorylase, and phosphofructo kinase) were identified by pull-down assay with GST-calumenin and solubilized SR. All the interactions were Ca$\^$2+/dependent. The present results suggest that calumenin plays an important role in Ca$\^$2+/ homeostasis of muscle cells.

• Food Science and Preservation
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• v.5 no.4
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• pp.342-345
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• 1998

This study was investigated to the structure of cell wall during maturation for the research of softening of jujube fruits. Cell was hardly combined with each other untill turning stage, but middle lamella of cell wall was splited at mature stage and was observed splited cell. The middle lamella of cell wall was not observed at green mature stage, but was observed at turning stage. Cell wall was degraded at mature stage. It was observed mitochondria, endoplasmic reticulum et. at in jujube fruit of green mature stage, but cytoplasm and organelle was attached on cell wall as vacuole was grown up after turning stage.

• YAKHAK HOEJI
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• v.30 no.3
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• pp.143-148
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• 1986

The effect of orally administered ginseng ethanol extract on potassium deficient and normal rat skeletal muscles was investigated in terms of Ca uptake by sarcoplastic reticulum fragments. The ginseng ethanol extract (100mg/kg/day) was administered orally to Sprague-Dawley rats for 21 days and their changes of body weights, $K^+$ content in skeletal muscles, and calcium uptake capacity of sarcoplamic reticulurn of each groups were measured. The growth rate of rats fed with the potassium deficient diet was significantly decreased compared to that of normal rats. Ginseng components did not show any effect on the decreased growth rate of the postassium deficient rats. Potassium content in skeletal muscle from potassium deficient rats was significantly reduced compared to that of normal rats. Ginseng components showed the tendency to prevent the reduction in potassium content of potassium deficient rats, but differences were not statistically significant. Calcium uptake of SR prepared from skeletal muscles of potassium deficient rats was increased significantly compared to that of normal rats. Ginseng components prevented such increase of calcium uptake by 30%. In summary, it can be concluded that ginseng may prevent the increase in Cauptake of SR obtained from potassium deficient rats.

• Molecules and Cells
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• v.40 no.1
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• pp.66-72
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• 2017

Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit $(p-eIF2)-{\alpha}$, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal ($0.5mg{\cdot}kg^{-1}{\cdot}day^{-1}$) alleviated cardiac hypertrophy and tissue fibrosis. Salubrinal also alleviated hypertrophic growth in endothelin 1 (ET1)-treated NRVMs. Therefore, the present results suggest that salubrinal may be a potentially efficacious drug for treating pathological cardiac remodeling.

• Biomolecules & Therapeutics
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• v.20 no.3
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• pp.346-351
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• 2012

Cells show various stress signs when they are challenged with severe physiological problems. Majority of such cellular stresses are conveyed to endoplasmic reticulum (ER) and unfolded protein response (UPR) serves as typical defense mechanism against ER stress. This study investigated an interaction between ER stress agents using macropage cell line Raw 264.7. When activated by lipopolysaccharide (LPS), the cell lines showed typical indicators of ER stress. Along with molecular chaperones, the activation process leads to the production of additional inflammatory mediators. Following activation, the macrophage cell line was further treated with TUN and characterized in terms of chaperone expression and cytokine secretion. When treated with TUN, the activated macrophage cell leads to increased secretion of IL-6 although expression of ER stress markers, GRP94 and GRP78 increased. The secretion of cytokines continued until the addition of BFA which inhibits protein targeting from ER to Golgi. However, secretion of cytokines was ceased upon dual treatments with BFA and TG. This result strongly implies that cells may differently deal with various polypeptides depending on the urgency in cellular function under ER stress. Considering IL-6 is one of the most important signal molecules in macrophage, the molecule might be able to circumvent ER stress and UPR to reach its targeting site.