Restoration of glutathione levels in vascular smooth muscle cells exposed to high glucose conditions

Powell, Lesley; Nally, S.M.; McMaster, Dorothy; Catherwood, Mark; Trimble, Elisabeth R.

doi:10.1016/s0891-5849(01)00648-7

Cited by 44 publications

(21 citation statements)

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“…GSH concentrations, reduced by glucose, were restored to normal by addition of the antioxidant, -lipoic acid. A similar result has been observed in human vascular smooth muscle cells (Powell et al 2001), mesangial cells (Catherwood et al 2002) and human peripheral mononuclear cells of patients with non-insulin-dependent diabetes (Arnalich et al 2001). -Lipoic acid not only functions as an antioxidant, but is reduced to dihydrolipoate intracellularly, thereby increasing the availability of the rate-limiting substrate in GSH synthesis, cysteine.…”

Section: Discussionsupporting

confidence: 82%

High glucose decreases intracellular glutathione concentrations and upregulates inducible nitric oxide synthase gene expression in intestinal epithelial cells

Powell¹,

Warpeha²,

Xu³

et al. 2004

Journal of Molecular Endocrinology

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Diabetes is associated with oxidative stress and increased concentrations of inflammatory cytokines. The aim of the study was to assess the effects of inflammatory cytokines and oxidative stress associated with increased glucose concentrations on inducible nitric oxide synthase (iNOS) promoter activity in intestinal epithelial cells. High-glucose (25 mmol/l) conditions reduced glutathione (GSH) concentrations in the human intestinal epithelial cell line, DLD-1. Addition of the antioxidant, α-lipoic acid, resulted in the restoration of GSH concentrations to normal. Upregulation of basal iNOS promoter activity was observed when cells were incubated in high glucose alone. This effect was significantly reduced by the addition of the antioxidant, α-lipoic acid, and completely blocked with inhibition of nuclear factor kappa B (NFκB) activity. Stimulation of cytokines (interleukin-1 beta, tumour necrosis factor-alpha, interferon-gamma) induced iNOS promoter activity in all conditions and this was accompanied by an increase in nitric oxide (NO) production. Inhibition of NFκB activity decreased, but did not completely inhibit, cytokine-induced iNOS promoter activity and subsequent production of NO. In conclusion, iNOS promoter activity induced by high concentrations of glucose is mediated in part through intracellular GSH and NFκB.

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Section: Discussionsupporting

confidence: 82%

High glucose decreases intracellular glutathione concentrations and upregulates inducible nitric oxide synthase gene expression in intestinal epithelial cells

Powell¹,

Warpeha²,

Xu³

et al. 2004

Journal of Molecular Endocrinology

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“…The difference to PKC␦ ϩ/ϩ SMCs was less pronounced under high glucose conditions (15 versus 22 mol/g protein, PϽ0.01), which represents a considerable oxidative stress leading to GSH consumption. 21,22 GSH is a tripeptide with a free sulfhydryl group and is of paramount importance in maintaining the reducing intracellular environment. 21,23 Consequently, increased GSH protected PKC␦ Ϫ/Ϫ SMCs against oxidative stress-induced cell death: treatment with 100 mol/L diethylmaleate (DEM), a sulfhydrylreactive agent, resulted in rapid depletion of GSH ( Figure 6A), followed by a drop in ATP levels ( Figure 6B) and cell death in PKC␦ ϩ/ϩ SMCs ( Figure 6C).…”

Section: Elevated Glutathione Levels Protect Pkc␦ ؊/؊ Smcsmentioning

confidence: 99%

“…21,22 GSH is a tripeptide with a free sulfhydryl group and is of paramount importance in maintaining the reducing intracellular environment. 21,23 Consequently, increased GSH protected PKC␦ Ϫ/Ϫ SMCs against oxidative stress-induced cell death: treatment with 100 mol/L diethylmaleate (DEM), a sulfhydrylreactive agent, resulted in rapid depletion of GSH ( Figure 6A), followed by a drop in ATP levels ( Figure 6B) and cell death in PKC␦ ϩ/ϩ SMCs ( Figure 6C). In contrast, PKC␦ -/-SMCs were less sensitive to DEM-induced cell death ( Figure 6A to C), tolerating up to 20-times higher concentrations of DEM than PKC␦ ϩ/ϩ SMCs (data not shown).…”

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confidence: 99%

Proteomic and Metabolomic Analysis of Vascular Smooth Muscle Cells

Mayr

Siow

Chung

et al. 2004

Circulation Research

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Abstract-Recent developments of proteomic and metabolomic techniques provide powerful tools for studying molecular mechanisms of cell function. Previously, we demonstrated that neointima formation was markedly increased in vein grafts of PKC␦-deficient mice compared with wild-type controls. To clarify the underlying mechanism, we performed a proteomic and metabolomic analysis of cultured vascular smooth muscle cells (SMCs) derived from PKC␦ ϩ/ϩ and PKC␦ Ϫ/Ϫ mice. Using 2-dimensional electrophoresis and mass spectrometry, we identified Ͼ30 protein species that were altered in PKC␦ Ϫ/Ϫ SMCs, including enzymes related to glucose and lipid metabolism, glutathione recycling, chaperones, and cytoskeletal proteins. Interestingly, nuclear magnetic resonance spectroscopy confirmed marked changes in glucose metabolism in PKC␦ Ϫ/Ϫ SMCs, which were associated with a significant increase in cellular glutathione levels resulting in resistance to cell death induced by oxidative stress. Furthermore, PKC␦ Ϫ/Ϫ SMCs overexpressed RhoGDI␣, an endogenous inhibitor of Rho signaling pathways. Inhibition of Rho signaling was associated with a loss of stress fiber formation and decreased expression of SMC differentiation markers. Thus, we performed the first combined proteomic and metabolomic study in vascular SMCs and demonstrate that PKC␦ is crucial in regulating glucose and lipid metabolism, controlling the cellular redox state, and maintaining SMC differentiation. (Circ Res. 2004;94:e87-e96.)Key Words: proteomics Ⅲ metabolomics Ⅲ smooth muscle cells Ⅲ PKC Ⅲ signal transduction P roteomic and metabolomic techniques are ideal for clarifying quantitative protein and metabolite changes in physiological and diseased conditions, respectively. [1][2][3][4][5] In vascular research, however, proteomics and metabolomics are still in their infancies 6 -8 and no studies have been performed so far comparing proteomic and metabolomic profiles in vascular smooth muscle cells (SMCs).PKC␦ represents a novel PKC isoform as characterized on the basis of its structure and maximal activation by diacylglycerol in the absence of calcium. 9,10 We recently developed knockout mice lacking PKC␦ and studied its effect on neointima formation in vein grafts. 11 We demonstrated that loss of PKC␦ markedly accelerated neointima formation, resulting in complete occlusion of the vessel lumen in one-third of the vein grafts. As with p53-deficient mice, 12 neointimal lesions in PKC␦ Ϫ/Ϫ vein grafts contained twice as many SMCs as wild-type controls and showed significantly lower numbers of apoptotic SMCs. 11 In vitro experiments revealed that SMCs derived from PKC␦ Ϫ/Ϫ mice were less sensitive to various apoptotic stimuli, including cytokine treatment. Their apoptotic resistance appeared to involve a loss of free radical generation as evidenced by redoxsensitive fluorescent dyes. 11 Besides modulating apoptosis, PKC␦ was found to be important for cytoskeleton rearrangement and cell migration. 13 However, the molecular mechanisms of resistance to apoptosis and cyt...

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“…21,24 Hyperglycemia can elevate intracellular oxidative stress through multiple mechanisms. 25,26 Accordingly, we tested the hypothesis that hyperglycemia-induced oxidative stress impairs DDAH activity, leading to an elevation of ADMA and inhibition of endothelium-derived synthesis of NO.…”

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confidence: 99%

Impaired Nitric Oxide Synthase Pathway in Diabetes Mellitus

et al. 2002

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Background-An endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine (ADMA), is elevated in patients with type 2 diabetes mellitus (DM). This study explored the mechanisms by which ADMA becomes elevated in DM. Methods and Results-Male Sprague-Dawley rats were fed normal chow or high-fat diet (nϭ5 in each) with moderate streptozotocin injection to induce type 2 DM. Plasma ADMA was elevated in diabetic rats (1.33Ϯ0.31 versus 0.48Ϯ0.08 mol/L; PϽ0.05). The activity, but not the expression, of dimethylarginine dimethylaminohydrolase (DDAH) was reduced in diabetic rats and negatively correlated with their plasma ADMA levels (PϽ0.05). DDAH activity was significantly reduced in vascular smooth muscle cells and human endothelial cells (HMEC-1) exposed to high glucose (25.5 mmol/L). The impairment of DDAH activity in vascular cells was associated with an accumulation of ADMA and a reduction in generation of cGMP. In human endothelial cells, coincubation with the antioxidant polyethylene glycol-conjugated superoxide dismutase (22 U/mL) reversed the effects of the high-glucose condition on DDAH activity, ADMA accumulation, and cGMP synthesis.

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Restoration of glutathione levels in vascular smooth muscle cells exposed to high glucose conditions

Cited by 44 publications

References 44 publications

High glucose decreases intracellular glutathione concentrations and upregulates inducible nitric oxide synthase gene expression in intestinal epithelial cells

High glucose decreases intracellular glutathione concentrations and upregulates inducible nitric oxide synthase gene expression in intestinal epithelial cells

Proteomic and Metabolomic Analysis of Vascular Smooth Muscle Cells

Impaired Nitric Oxide Synthase Pathway in Diabetes Mellitus

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