• Biomolecules & Therapeutics
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• 제20권3호
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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.

• 대한의생명과학회지
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• 제21권2호
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• pp.126-130
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• 2015

There are several studies that show hypothermia improves cellular ischemia damages on experimental and clinical bases. However, its exact molecular mechanisms are unclear. In this study, we demonstrate that hypothermia induced insulin-like growth factor 1 (IGF1) gene expression, and its expression was dramatically decreased under ischemic insults. It was also demonstrated that hypothermia activated endoplasmic reticulum (ER) stress sensors especially both the phosphorylation of $eIF2{\alpha}$ (eukaryotic translation initiation factor 2 alpha) and ATF6 (activating transcription factor-6) proteolytic cleavage. However, the factors of apoptosis and autophagy were not associated with hypothermia. We suggest that hypothermia-treated IGF1 gene expression after ischemia may show a good possibility for the development of treatments and diagnostic methods in cerebral ischemic damages.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2007년도 제48회 학술심포지움 및 추계국제학술대회
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• pp.84.1-84.1
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• 2007

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• BMB Reports
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• 제50권3호
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• pp.144-149
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• 2017

Ceramides are the major sphingolipid metabolites involved in cell survival and apoptosis. When HepG2 hepatoma cells were treated with celecoxib, the expression of the genes in de novo sphingolipid biosynthesis and sphingomyelinase pathway was upregulated and cellular ceramide was elevated. In addition, celecoxib induced endoplasmic reticulum (ER) stress in a time-dependent manner. SPTLC2, a subunit of serine palmitoyltransferase, was overexpressed by adenovirus. Adenoviral overexpression of SPTLC2 (AdSPTLC2) decreased cell viability of HEK293 and HepG2 cells. In addition, AdSPTLC2 induced apoptosis via the caspase-dependent apoptotic pathway and elevated cellular ceramide, sphingoid bases, and dihydroceramide. However, overexpression of SPTLC2 did not induce ER stress. Collectively, celecoxib activates de novo sphingolipid biosynthesis and the combined effects of elevated ceramide and transcriptional activation of ER stress induce apoptosis. However, activation of de novo sphingolipid biosynthesis does not activate ER stress in hepatoma cells and is distinct from the celecoxib-mediated activation of ER stress.

• 생명과학회지
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• 제28권10호
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• pp.1186-1192
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• 2018

비만에 의한 근형질세망 스트레스(Endoplasmic stress, ER stress) 발생은 비접힙 단백질의 축적으로 근육내 대사와 근기능 저하를 초래한다. 유산소 운동과 폴리페놀은 비만에 유도된 염증성 사이토카인과 ER stress를 감소시키는 것으로 잘 알려졌다. 그러나 신체활동과 약물에 의한 염증성 사이토카인과 ER stress 변인들의 변화에 선택적인 반응이 있는지에 대한 연구는 이루어지지 않았다. 따라서, 이 연구의 목적은 유산소 운동과 폴리페놀섭취에 따른 골격근내 ER stress 관련 변인에 우선적인 효과가 있는지 비교분석하고자 하였다. 이 연구의 목적을 위해 (1) 정상식이 그룹, (2) 60% 고지방식이 그룹, (3) 고지방식와 레스베라트롤 25 mg/kg 그룹, (4) 고지방식이와 크리신 50 mg/kg 투여 그룹, (5) 고지방식이와 운동 그룹으로 나누어 실시하였다. 레스베라트롤과 크리신 그룹은 16주간 경구 투여 하였고, 운동 그룹은 1일 40-60분간 10-14 m/min의 속도로 주 4일, 총 16주간 트레드밀 운동을 수행하였다. 운동그룹에서 $IRE1{\alpha}$, BIP/GRP78는 고지방 식이 그룹과 비교하여 유의하게 낮아졌다(p<0.05). 고지방식이와 레스베라트롤 투여 그룹에서 ATF6, $IRE1{\alpha}$, BIP/GRP78는 고지방식이 그룹과 비교하여 유의하게 낮아졌다(p<0.05). 고지방식이와 크리신 투여 그룹은 고지방식이 그룹과 비교하여 ATF6가 유의하게 낮아졌다(p<0.05). 이러한 결과는 유산소 운동과 레스베라트롤, 크리신 섭취에 의해 ER stress 관련 변인을 조절할 수 있다. 그러나 유산소 운동은 고지방 식이에 의해 유도되는 ER stress 개선이 더욱 효과적인 것으로 나타났다.

• Parasites, Hosts and Diseases
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• 제60권5호
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• pp.371-371
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• 2022

• BMB Reports
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• 제42권11호
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• pp.719-724
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• 2009

Recent studies have revealed that endoplasmic reticulum (ER) disturbance is involved in the pathophysiology of neurodegenerative disorders, contributing to the activation of the ER stress-mediated apoptotic pathway. Therefore, we investigated here the molecular mechanisms underlying the ER-mitochondria axis, focusing on calcium as a potential mediator of cell death signals. Using NT2 cells treated with brefeldin A or tunicamycin, we observed that ER stress induces changes in the mitochondrial function, impairing mitochondrial membrane potential and distressing mitochondrial respiratory chain complex Moreover, stress stimuli at ER level evoked calcium fluxes between ER and mitochondria. Under these conditions, ER stress activated the unfolded protein response by an overexpression of GRP78, and also caspase-4 and-2, both involved upstream of caspase-9. Our findings show that ER and mitochondria interconnection plays a prominent role in the induction of neuronal cell death under particular stress circumstances.

• BMB Reports
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• 제45권5호
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• pp.317-322
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• 2012

2-deoxy-D-glucose(2DG)-caused endoplasmic reticulum (ER) stress inhibits protein phosphorylation at tyrosine residues. However, the accurate regulatory mechanisms, which determine the inflammatory response of chondrocytes to ER stress via protein tyrosine phosphorylation, have not been systematically evaluated. Thus, in this study, we examined whether protein phosphorylation at tyrosine residues can modulate the expression and glycosylation of COX-2, which is reduced by 2DG-induced ER stress. We observed that protein tyrosine phosphatase (PTP) inhibitors, sodium orthovanadate (SOV), and phenylarsine oxide (PAO) significantly decreased expression of ER stress inducible proteins, glucose-regulated protein 94 (GRP94), and CCAAT/ enhancer-binding-protein- related gene (GADD153), which was induced by 2DG. In addition, we demonstrated that SOV and PAO noticeably restored the expression and glycosylation of COX-2 after treatment with 2DG. These results suggest that protein phosphorylation of tyrosine residues plays an important role in the regulation of expression and glycosylation during 2DG-induced ER stress in rabbit articular chondrocytes.

• Biomolecules & Therapeutics
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• 제15권4호
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• pp.240-244
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• 2007

Cigarette smoking causes serious health problems in humans, especially if smoking habits are established during their adolescence. Nicotine is known to mutate DNA and interfere with apoptosis. Apoptosis is considered as a potent defense mechanism against cellular damaging agents. This study aims to investigate the effect of nicotine on the progression of apoptosis induced under ER stress conditions using four different established cell lines: HEK293, 3T3-L1, C2C12, and HepG2. When treated with nicotine, the progression of apoptosis was notably inhibited in the four cell lines according to the assays of caspase-3 activation and DNA fragmentation. In ER-stressed cells, nicotine appears to inhibit the progression of apoptosis in a concentration-dependent manner. When cells were treated with nicotine prior to ER stress, GRP94 level significantly increased compared to other ER stress markers of PDI and GRP78. This observation suggests that the inhibitory effect of nicotine may results from up-regulation of GRP94, an anti-apoptotic chaperone, under nicotine treatment. Taken together, the present study strongly implies that nicotine may inhibit apoptosis, caused by prolonged ER stress, based on promotion of GRP94 expression.

• BMB Reports
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• 제38권6호
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• pp.709-716
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• 2005

Apoptosis and necrosis are distinguished by modality primarily. Here we show an apoptosis occurred instantly, induced by $300\;{\mu}M$ W-7 ((N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride), inhibitor of calmodulin), which demonstrated necrotic modality. As early as 30 min after W-7 addition, apoptotic (sub-diploid) peak could be detected by fluorescence-activated cell sorter (FACS), “DNA ladders” began to emerge also at this time point, activity of caspase-3 elevated obviously within this period. Absence of mitochondrial membrane potential (MMP) reduction and cytochrome c, AIF (apoptosis inducing factor) release, verified that this rapid apoptosis did not proceed through mitochondria pathway. Activation of caspase-12 and changes of other endoplasmic reticulum (ER) located proteins ascertained that ER pathway mediated this necrosis-like apoptosis. Our findings suggest that it is not credible to judge apoptosis by modality. Elucidation of ER pathway is helpful to comprehend the pathology of diseases associated with ER stress, and may offer a new approach to the therapy of cancer and neurodegenerative diseases.