- Oxidative Stress Causes Vascular Insulin Resistance in OLETF Rat Through Increased IRS-1 Degradation.
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Jung Lae Park, Young Sil Lee, Bo Hyun Kim, Yang Ho Kang, In Ju Kim, Yong Ki Kim, Seok Man Son
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Korean Diabetes J. 2007;31(1):22-32. Published online January 1, 2007
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DOI: https://doi.org/10.4093/jkda.2007.31.1.22
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- BACKGROUND
Insulin resistance and oxidative stress have been reported to play essential pathophysiological roles in diabetic cardiovascular complication. The relationship between insulin resistance and oxidative stress in vasculature remains unclear. The study was conducted to assess whether oxidative stress induce vascular insulin resistance in OLETF rat, a model of type 2 diabetes METHODS: We used OLETF rats (20/30/40 weeks, n = 5/5/5), as models of type 2 DM, and LETO rats (20/30/40 weeks, n = 5/5/5) as controls. Aortas of each rats were extracted. Superoxide anion production was detected by NBT assay and lucigenin assay. 8-hydroxyguanosine (OHdG) and nitrotyrosine were detected as markers of oxidative stress in 20 and 40 weeks groups. The glucose uptake of aortas was measured by detecting 2-deoxyglucose uptake in both groups. The expression of IR, IRS-1, PI3-K and Akt/PKB were detected by immuno precipitation and immunoblotting in 20, 30 and 40 weeks groups RESULTS: Superoxide anion production and markers of oxidative stress (8-OHdG, nitrotyrosine) were significantly increased in aortas of OLETF rats compared with controls. Aortas of OLETF rats exhibited decreased IRS-1 content and increased phosphorylation of IRS-1 at Ser307 compared with LETO rats. There were no significant differences in expressions of IR, PI3-K and Akt/PKB between two groups CONCLUSION: These results suggest that oxidative stress induces insulin resistance in vasculature of OLETF rat specifically through increasing serine phosphorylation of IRS-1 and its degradation by a proteasome-dependent pathway, providing an alternative mechanism that may explain the association with insulin resistance and diabetic vascular complications.
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Citations
Citations to this article as recorded by  - Anti-diabetic effects of benfotiamine on an animal model of type 2 diabetes mellitus
Kang Min Chung, Wonyoung Kang, Dong Geon Kim, Hyun Ju Hong, Youngjae Lee, Chang-Hoon Han
Korean Journal of Veterinary Research.2014; 54(1): 21. CrossRef
- High Glucose Modulates Vascular Smooth Muscle Cell Proliferation Through Activation of PKC-sigma-dependent NAD(P)H oxidase.
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Bo Hyun Kim, Chang Won Lee, Jung Lae Park, Yang Ho Kang, In Ju Kim, Yong Ki Kim, Seok Man Son
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Korean Diabetes J. 2006;30(6):416-427. Published online November 1, 2006
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DOI: https://doi.org/10.4093/jkda.2006.30.6.416
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2,228
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- BACKGROUND
Oxidative stress is thought to be one of the causative factors contributing to macrovascular complications in diabetes. However, the mechanisms of development and progression of diabetic vascular complications are poorly understood. We hypothesized that PKC-sigma isozyme contributes to ROS generation and determined their roles in the critical intermediary signaling events in high glucose-induced proliferation of vascular smooth muscle (VSM) cells. METHODS: We treated primary cultured rat aortic smooth muscle cells for 72 hours with medium containing 5.5 mmol/L D-glucose (normal glucose), 30 mmol/L D-glucose (high glucose) or 5.5 mmol/L D-glucose plus 24.5 mmol/L mannitol (osmotic control). We then measured cell number, BrdU incorporation, cell cycle and superoxide production in VSM cells. Immunoblotting of PKC isozymes using phoshospecific antibodies was performed, and PKC activity was also measured. RESULTS: High glucose increased VSM cell number and BrdU incorporation and displayed significantly greater percentages of S and G2/M phases than compared to 5.5 mmol/L glucose and osmotic control. The nitroblue tetrazolium (NBT) staining in high glucose-treated VSM cell was more prominent compared with normal glucose-treated VSM cell, which was significantly inhibited by DPI (10 micrometer), but not by inhibitors for other oxidases. High glucose also markedly increased activity of PKC-sigma isozyme. When VSM cells were treated with rottlerin, a specific inhibitor of PKC-sigma or transfected with PKC-sigma siRNA, NBT staining and NAD(P)H oxidase activity were significantly attenuated in the high glucose-treated VSM cells. Furthermore, inhibition of PKC-sigma markedly decreased VSM cell number by high glucose. CONCLUSION: These results suggest that high glucose-induced VSM cell proliferation is dependent upon activation of PKC-sigma, which may responsible for elevated intracellular ROS production in VSM cells, and this is mediated by NAD(P)H oxidase.
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Citations
Citations to this article as recorded by - High Glucose and/or Free Fatty Acid Damage Vascular Endothelial Cells via Stimulating of NAD(P)H Oxidase-induced Superoxide Production from Neutrophils
Sang Soo Kim, Sun Young Kim, Soo Hyung Lee, Yang Ho Kang, In Ju Kim, Yong Ki Kim, Seok Man Son
Korean Diabetes Journal.2009; 33(2): 94. CrossRef
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