- The Effect of Chronic High Glucose Concentration on Endoplasmic Reticulum Stress in INS-1 Cells.
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Mi Kyung Kim, Hye Young Seo, Tae Sung Yun, Nam Kyung Kim, Yu Jin Hah, Yun Jung Kim, Ho Chan Cho, Young Yun Jang, Hye Soon Kim, Seong Yeol Ryu, In Kyu Lee, Keun Gyu Park
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Korean Diabetes J. 2008;32(2):112-120. Published online April 1, 2008
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DOI: https://doi.org/10.4093/kdj.2008.32.2.112
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 Abstract
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- BACKGROUND
The highly developed endoplasmic reticulum (ER) structure is one of the characteristic features of pancreatic beta-cells. Recent study showed that ER stress causes beta-cell dysfunction. However, little is known about the effects of high glucose concentration on induction of ER stress in pancreatic beta-cells. Therefore, this study was designed to evaluate whether exposure of high glucose concentration in rat insulinoma cell line, INS-1 cell induces ER stress and whether ER stress decreases insulin gene expression. METHODS: The effect of 30 mM glucose on insulin expression and secretion in INS-1 cells was evaluated by Northern blot analysis and glucose-stimulated insulin secretion (GSIS). Cell viability was evaluated by XTT assay. The effect of 30 mM glucose on phosphorylation of eIF2alpha and CHOP expression, which are markers of ER stress were evaluated by Western blot analysis. RT-PCR analysis was performed to determine whether high glucose concentration induces XBP-1 splicing. To investigate whether ER stress decreases insulin gene expression, the effect of tunicamycin on insulin mRNA expression was evaluated by Northern blot analysis. RESULTS: The prolonged exposure of INS-1 cells with the 30 mM glucose concentration decreased insulin mRNA expression in a time dependent manner and impaired GSIS while did not influence on cell viability. 30 mM glucose increased phosphorylation of eIF2alpha, XBP-1 splicing and CHOP expression in INS-1 cells. Tunicamycin-treated INS-1 increased XBP-1 splicing and decreased insulin mRNA expression in a dose dependent manner. CONCLUSION: This study showed that prolonged exposure of INS-1 with high glucose concentration induces ER stress and ER stress decreases insulin gene expression. Further studies about underlying molecular mechanism by which ER stress induces beta-cell dysfunction are needed.
- Ascochlorin Derivative, AS-6, Inhibits TNF-alpha-Induced fractalkine, MCP-1 and VCAM-1 Expression in Rat Aortic Smooth Muscle Cells.
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Young Yun Jang, Sang Yoon Kim, Nam Keong Kim, Mi Kyung Kim, Hee Kyoung Kim, Hye Soon Kim, Chang Wook Nam, Seong Yeol Ryu, Sung Il Nam, Keun Gyu Park
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Korean Diabetes J. 2005;29(5):401-408. Published online September 1, 2005
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Abstract
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- BACKGOUND: Inflammation is one of the key mechanisms in the development and progression of atherosclerosis. Accumulating evidence suggests that peroxisome proliferators- activated receptorgamma(PPARgamma) plays an important role in the prevention of arterial inflammation and the formation of atherogenesis. This study was designed to evaluate whether the new synthetic PPARgamma, ascochlorin-6(AS-6) has anti-inflammatory and anti-atherogenic effects in primary cultured rat vascular smooth muscle cells(VSMCs). METHODS: Rat VSMCs were isolated and cultured. Northern and Western blot analyses were performed to evaluate the effects of AS-6 on the expressions of tumor necrosis factor (TNF)-alpha-stimulated fractalkine, monocyte chemoattractant protein(MCP)-1 and vascular cell adhesion molecule (VCAM)-1 in VSMCs. A gel shift assay was performed to examine the mechanism by which AS-6 inhibits the expressions of fractalkine, MCP-1 and VCAM-1. RESULTS: TNF-alpha markedly induced the expressions of fractalkine, MCP-1 and VCAM-1 in primary cultured VSMCs. AS-6 inhibited the expressions of TNF-alpha-stimulated fractalkine, MCP-1 and VCAM-1 in primary cultured VSMCs. The result of the gel shift assay suggested the inhibitory effects of AS-6 on the expressions of TNF-alpha-stimulated fractalkine, MCP-1 and VCAM-1 were mediated through a nuclear factor kappaB associated pathway. CONCLUSION: The present study shows that AS-6 has anti-inflammatory effects on VSMCs, suggesting the possibility for the use of AS-6 for prevention of the development and progression of atherosclerosis.
- Comparison of the Relationship of Leptin to Metabolic Parameters Between Premenopausal Normal Weight and Obese Women.
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Hee Kyoung Kim, Keun Gyu Park, Mi Kyung Kim, Young Yun Jang, Sang Yoon Kim, Eui Dal Jung, Hye Soo Kim, Ju Ho Do, In Kyu Lee
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Korean Diabetes J. 2005;29(3):223-230. Published online May 1, 2005
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Abstract
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- BACKGROUND
Leptin is mainly secreted from adipose tissue, and it is a crucial factor for metabolic syndrome that is characterized by obesity, insulin resistance, hypertension and dyslipidemia. We measured the serum leptin concentrations and compared them with the body fat distribution and metabolic risk factors in premenopausal normal weight and obese women. METHODS: 231 premenopausal obese women participated in this study. The subjects were grouped based on their body mass index(BMI). The number of normal weight group women(BMI<25kg/m2) and the number of obese group women(BMI> or = 25kg/m2) were 90 and 141, respectively. We measured the plasma leptin concentration and such metabolic risk factors as fasting glucose, insulin, triglyceride(TG), systolic blood pressure(SBP) and diastolic blood pressure(DBP). The subcutaneous adipose tissue area(SAT) and the visceral adipose tissue area(VAT) were determined by computed tomography. The BMI, waist to hip ratio(WHR) and homeostasis model assessment(HOMA-IR) were calculated. RESULTS: In the obese group, the leptin levels were positively correlated with the BMI and SAT as well as with such metabolic risk factors as fasting serum glucose, insulin, HOMA-IR, TG, SBP and DBP. Although leptin levels were positively correlated with BMI and SAT in the normal weight group, they were not correlated with the metabolic risk factors. CONCLUSION: The present study showed that the leptin levels in the normal weight group were not associated with the metabolic risk factors. Therefore, the degree of obesity must be considered before leptin can be used as a predictor for metabolic syndrome including diabetes and coronary heart disease
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