Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Diabetes mellitus is associated with increased ROS generation, oxidative injury and obesity. To elucidate the relationship between nutrition and ROS generation, we have investigated the effect of glucose challenge on ROS generation by leucocytes, p47phox protein, a key protein in the enzyme NADPH oxidase and alpha-tocopherol levels. Blood samples were drawn from 14 normal subjects prior to, at 1, 2 and 3 h following ingestion of 75 g glucose. ROS generation by polymorphonuclear leucocytes (PMNL) and mononuclear cells (MNC) increased to a peak of 244 +/- 42% and 233 +/- 34% of the basal respectively at 2h. The levels of p47phox in MNC homogenates increased significantly at 2 h and 3 h after glucose intake. alpha-Tocopherol levels decreased significantly at 1 h, 2 h and 3 h. We conclude that glucose intake stimulates ROS generation and p417phox of NADPH oxidase; increases oxidative load and causes a fall in alpha-tocopherol concentration.
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PMID:Glucose challenge stimulates reactive oxygen species (ROS) generation by leucocytes. 1094 14

Diabetes is a major risk factor for premature atherosclerosis, and oxidative stress appears to be an important mechanism. Previously, we showed that diabetic monocytes produce increased superoxide anion (O(2)(-)), and alpha-tocopherol (AT) supplementation decreases this. The aim of this study was to elucidate the mechanism(s) of O(2)(-) release and inhibition by AT under hyperglycemic (HG) conditions in monocytes. O(2)(-) release, protein kinase C (PKC) activity, and translocation of PKC-alpha and -betaII and p47phox were increased in THP-1 cells (human monocytic cell line) under HG (15 mmol/l glucose) conditions, whereas AT supplementation inhibited these changes. AT, NADPH oxidase inhibitors (apocynin and diphenyleneiodonium chloride [DPI]), and an inhibitor to PKC-alpha and other isoforms (2,2',3,3',4,4'-hexahydroxy-1,1'-biphenyl-6,6'-dimethanol dimethyl ether [HBDDE]) but not PKC-beta II (LY379196) decreased O(2)(-) release and p47phox translocation. Antisense oligodeoxynucleotides to PKC-alpha and p47phox but not to PKC-betaII inhibited HG-induced O(2)(-) release and p47phox translocation in THP-1 cells. Under HG conditions, reactive oxygen species release from monocytes was not inhibited by agents affecting mitochondrial metabolism but was inhibited in human endothelial cells. We conclude that under HG conditions, monocytic O(2)(-) release is dependent on NADPH oxidase activity but not the mitochondrial respiratory chain; HG-induced O(2)(-) release is triggered by PKC-alpha, and AT inhibits O(2)(-) release via inhibition of PKC-alpha.
Diabetes 2002 Oct
PMID:Alpha-tocopherol decreases superoxide anion release in human monocytes under hyperglycemic conditions via inhibition of protein kinase C-alpha. 1235 46

High glucose (HG) is the underlying factor contributing to long term complications of diabetes mellitus. The molecular mechanisms transforming the glomerular mesangial cell phenotype to cause nephropathy including diacylglycerol-sensitive protein kinase C (PKC) are still being defined. Reactive oxygen species (ROS) have been postulated as a unifying mechanism for HG-induced complications. We hypothesized that in HG an interaction between ROS generation, from NADPH oxidase, and PKC suppresses mesangial Ca2+ signaling in response to endothelin-1 (ET-1). In primary rat mesangial cells, growth-arrested (48 h) in 5.6 mM (NG) or 30 mm (HG) glucose, the total cell peak [Ca2+]i response to ET-1 (50 nM) was 630 +/- 102 nM in NG and was reduced to 159 +/- 15 nM in HG, measured by confocal imaging. Inhibition of PKC with phorbol ester down-regulation in HG normalized the ET-1-stimulated [Ca2+]i response to 541 +/- 74 nM. Conversely, an inhibitory peptide specific for PKC-zeta did not alter Ca2+ signaling in HG. Furthermore, overexpression of conventional PKC-beta or novel PKC-delta in NG diminished the [Ca2+]i response to ET-1, reflecting the condition observed in HG. Likewise, catalase or p47phox antisense oligonucleotide normalized the [Ca2+]i response to ET-1 in HG to 521 +/- 58 nM and 514 +/- 48 nM, respectively. Pretreatment with carbonyl cyanide m-chlorophenylhydrazone or rotenone did not restore Ca2+ signaling in HG. Detection of increased intracellular ROS in HG by dichlorofluorescein was inhibited by catalase, diphenyleneiodonium, or p47phox antisense oligonucleotide. HG increased p47phox mRNA by 1.7 +/- 0.1-fold as measured by reverse transcriptase-PCR. In NG, H2O2 increased membrane-enriched PKC-beta and -delta, suggesting activation of these isozymes. HG-enhanced immunoreactivity of PKC-delta visualized by confocal imaging was attenuated by diphenyleneiodium chloride. Thus, mesangial cell [Ca2+]i signaling in response to ET-1 in HG is attenuated through an interaction mechanism between NADPH oxidase ROS production and diacylglycerol-sensitive PKC.
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PMID:High glucose-suppressed endothelin-1 Ca2+ signaling via NADPH oxidase and diacylglycerol-sensitive protein kinase C isozymes in mesangial cells. 1282 78

Enhanced tissue angiotensin (Ang) II levels have been reported in diabetes and might lead to cardiac dysfunction through oxidative stress. This study examined the effect of blocking the Ang II type 1 (AT1) receptor on high glucose-induced cardiac contractile dysfunction. Rat ventricular myocytes were maintained in normal- (NG, 5.5 mmol/L) or high- (HG, 25.5 mmol/L) glucose medium for 24 hours. Mechanical and intracellular Ca2+ properties were assessed as peak shortening (PS), time to PS (TPS), time to 90% relengthening (TR90), maximal velocity of shortening/relengthening (+/-dL/dt), and intracellular Ca2+ decay (tau). HG myocytes exhibited normal PS; decreased +/-dL/dt; and prolonged TPS, TR90, and tau. Interestingly, the HG-induced abnormalities were prevented with the AT1 blocker L-158,809 (10 to 1000 nmol/L) but not the Janus kinase-2 (JAK2) inhibitor AG-490 (10 to 100 micromol/L). The only effect of AT1 blockade on NG myocytes was enhanced PS at 1000 nmol/L. AT1 antagonist-elicited cardiac protection against HG was nullified by the NADPH oxidase activator sodium dodecyl sulfate (80 micromol/L) and mimicked by the NADPH oxidase inhibitors diphenyleneiodonium (10 micromol/L) or apocynin (100 micromol/L). Western blot analysis confirmed that the protein abundance of NADPH oxidase subunit p47phox and the AT1 but not the AT2 receptor was enhanced in HG myocytes. In addition, the HG-induced increase of p47phox was prevented by L-158,809. Enhanced reactive oxygen species production observed in HG myocytes was prevented by AT1 blockade or NADPH oxidase inhibition. Collectively, our data suggest that local Ang II, acting via AT1 receptor-mediated NADPH oxidase activation, is involved in hyperglycemia-induced cardiomyocyte dysfunction, which might play a role in diabetic cardiomyopathy.
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PMID:AT1 blockade prevents glucose-induced cardiac dysfunction in ventricular myocytes: role of the AT1 receptor and NADPH oxidase. 1284 13

Oxidative stress is implicated to play an important role in the development of diabetic vascular complications, including diabetic nephropathy. It is unclear whether oxidative stress is primarily enhanced in the diabetic glomeruli or whether it is merely a consequence of diabetes-induced glomerular injury. To address this issue, we examined diabetic glomeruli to determine whether oxidative stress is enhanced, as well as examined the role of protein kinase C (PKC)-beta activation in modulating NADPH oxidase activity. Urinary 8-hydroxydeoxyguanosine excretion and its intense immune-reactive staining in the glomeruli were markedly higher in diabetic than in control rats, and these alterations were ameliorated by a treatment with a selective PKC-beta inhibitor, ruboxistaurin (RBX; LY333531) mesylate, without affecting glycemia. NADPH oxidase activity, which was significantly enhanced in diabetic glomeruli and the source of reactive oxygen species (ROS) generation, was also improved by RBX treatment by preventing the membranous translocation of p47phox and p67phox from cytoplasmic fraction without affecting their protein levels. Adenoviral-mediated PKC-beta(2) overexpression enhanced ROS generation by modulating the membranous translocation of p47phox and p67phox in cultured mesangial cells. We now demonstrate that oxidative stress is primarily enhanced in the diabetic glomeruli due to a PKC-beta-dependent activation of NADPH oxidase resulting in ROS generation.
Diabetes 2003 Oct
PMID:Translocation of glomerular p47phox and p67phox by protein kinase C-beta activation is required for oxidative stress in diabetic nephropathy. 1451 46

The effects of intermittent and constant high glucose in the formation of nitrotyrosine and 8-hydroxydeoxyguanosine (markers of oxidative stress), as well as the possible linkage between oxidative stress and apoptosis in endothelial cells, have been evaluated. Stable high glucose increased nitrotyrosine, 8-hydroxydeoxyguanosine (8-OHdG), and apoptosis levels. However, these effects were more pronounced in intermittent high glucose. Protein kinase C (PKC) was elevated in both such conditions, particularly in intermittent glucose. The adding of the PKC inhibitors bisindolylmaleimide-I and LY379196, a specific inhibitor of PKC-beta isoforms, normalized nitrotyrosine and reduced 8-OHdG concentration and cell apoptosis in both stable and intermittent high glucose. Similar results were obtained with the MnSOD mimetic Mn(III)tetrakis(4-benzoic acid)porphyrin chloride that normalized nitrotyrosine, 8-OHdG, and apoptosis and inhibited PKC activation. NAD(P)H oxidase was also measured. NAD(P)H oxidase components p47phox, p67phox, and p22phox was overexpressed during both stable and intermittent high glucose. PKC inhibition and MnSOD mimetic normalized this phenomenon. In conclusion, our study shows that the exposure of endothelial cells to both stable and intermittent high glucose stimulates reactive oxygen species overproduction also through PKC-dependent activation of NAD(P)H oxidase, leading to increased cellular apoptosis. Our data suggest that glucose fluctuations may also be involved in the development of vascular injury in diabetes.
Diabetes 2003 Nov
PMID:Intermittent high glucose enhances apoptosis related to oxidative stress in human umbilical vein endothelial cells: the role of protein kinase C and NAD(P)H-oxidase activation. 1457 99

Oxidative stress may be involved in the development of vascular complications associated with diabetes; however, the molecular mechanism responsible for increased production of free radicals in diabetes remains uncertain. Therefore, we examined whether acute hyperinsulinemia increases the production of free radicals and whether this condition affects proliferative extracellular signal-regulated kinase (ERK-1 and -2) signaling in human fibroblasts in vitro. Insulin treatment significantly increased intracellular superoxide anion (O(2)(-)) production, an effect completely abolished by Tiron, a cell-permeable superoxide dismutase (SOD) mimetic and by polyethylene glycol (PEG)-SOD, but not by PEG catalase. Furthermore, insulin-induced O(2)(-) production was attenuated by the NAD(P)H inhibitor apocynin, but not by rotenone or oxypurinol. Inhibition of the phosphatidylinositol 3'-kinase (PI 3'-kinase) pathway with LY294002 blocked insulin-stimulated O(2)(-) production, suggesting a direct involvement of PI 3'-kinase in the activation of NAD(P)H oxidase. The insulin-induced free radical production led to membranous translocation of p47phox and markedly enhanced ERK-1 and -2 activation in human fibroblasts. In conclusion, these findings provided direct evidence that elevated insulin levels generate O(2)(-) by an NAD(P)H-dependent mechanism that involves the activation of PI 3'-kinase and stimulates ERK-1- and ERK-2-dependent pathways. This effect of insulin may contribute to the pathogenesis and progression of cardiovascular disease in the insulin resistance syndrome.
Diabetes 2004 May
PMID:Insulin generates free radicals by an NAD(P)H, phosphatidylinositol 3'-kinase-dependent mechanism in human skin fibroblasts ex vivo. 1511 5

Although diabetes is a major risk factor for vascular diseases, e.g., hypertension and atherosclerosis, mechanisms that underlie the "risky" aspects of diabetes remain obscure. The current study is intended to examine the notion that diabetic endothelial dysfunction stems from a heightened state of oxidative stress induced by an imbalance between vascular production and scavenging of reactive oxygen/nitrogen species. Goto-Kakizaki (GK) rats were used as a genetic animal model for non-obese type II diabetes. Nitric oxide (NO) bioavailability and O2- generation in aortic tissues of GK rats were assessed using the Griess reaction and a lucigenin-chemiluminescence-based technique, respectively. Organ chamber-based isometric tension studies revealed that aortas from GK rats had impaired relaxation responses to acetylcholine whereas a rightward shift in the dose-response curve was noticed in the endothelium-independent vasorelaxation exerted by the NO donor sodium nitroprusside. An enhancement in superoxide (O2-) production and a diminuation in NO bioavailability were evident in aortic tissues of GK diabetic rats. Immunoblotting and high-performance liquid chromatography (HPLC)-based techniques revealed, respectively, that the above inverse relationship between O2- and NO was associated with a marked increase in the protein expression of nitric oxide synthase (eNOS) and a decrease in the level of its cofactor tetrahydrobiopterin (BH4) in diabetic aortas. Endothelial denudation by rubbing or the addition of pharmacological inhibitors of eNOS (e.g. N(omega)-nitro-L-arginine methyl ester (L-NAME)), and NAD(P)H oxidase (e.g. diphenyleneiodonium, apocynin) strikingly reduced the diabetes-induced enhancement in vascular O2- production. Aortic contents of key markers of oxidative stress (isoprostane F2alpha III, protein-bound carbonyls, nitrosylated protein) in connection with the protein expression of superoxide generating enzyme NAD(P)H oxidase (e.g. p47phox, pg91phox), a major source of reactive oxygen species in vascular tissue, were elevated as a function of diabetes. In contrast, the process involves in the vascular inactivation of reactive oxygen species exemplified by the activity of CuZnSOD was reduced in this diseased state. Our studies suggest that diabetes produces a cascade of events involving production of reactive oxygen species from the NADPH oxidase leading to oxidation of BH4 and uncoupling of NOS. This promotes the oxidative inactivation of NO with subsequent formation of peroxynitrite. An alteration in the balance of these bioactive radicals in concert with a defect in the antioxidant defense counteracting mechanism may favor a heightened state of oxidative stress. This phenomenon could play a potentially important role in the pathogenesis of diabetic endothelial dysfunction.
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PMID:Nitric oxide dynamics and endothelial dysfunction in type II model of genetic diabetes. 1577 79

Reduced levels of cGMP-dependent protein kinase I (PKG-I) in vasculature have been shown to contribute to diabetic vascular dysfunctions. However, the underlying mechanisms remain unknown. In this report, using primary rat aortic smooth muscle cells (VSMC), we investigated the mechanisms of glucose-mediated regulation of PKG-I expression. Our data showed that high glucose (30 mM glucose) exposure significantly reduced PKG-I production (protein and mRNA levels) as well as PKG-I activity in cultured VSMC. Glucose-mediated decreases in PKG-I levels were inhibited by a superoxide scavenger (tempol) or NAD(P)H oxidase inhibitors (diphenylene iodonium or apocynin). High glucose exposure time-dependently increased superoxide production in VSMC, which was abolished by tempol or apocynin treatment, but not by other inhibitors of superoxide-producing enzymes (L-NAME, rotenone, or oxypurinol). Total protein levels and phosphorylated levels of p47phox (an NADPH oxidase subunit) were increased in VSMC after high glucose exposure. Transfection of cells with siRNA-p47phox abolished glucose-induced superoxide production and restored PKG-I protein levels in VSMC. Treatment of cells with PKC inhibitor prevented glucose-induced p47phox expression/phosphorylation and superoxide production and restored the PKG-I levels. Decreased PKG-I protein levels were also found in femoral arteries from diabetic mice, which were associated with the decreased DEA-NONOate-induced vasorelaxation. Taken together, the present results suggest that glucose-mediated down-regulation of PKG-I expression in VSMC occurs through PKC-dependent activation of NAD(P)H oxidase-derived superoxide production, contributing to diabetes-associated vessel dysfunctions.
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PMID:Glucose down-regulation of cGMP-dependent protein kinase I expression in vascular smooth muscle cells involves NAD(P)H oxidase-derived reactive oxygen species. 1732 Jul 67

NADPH oxidase inhibitors such as diphenylene iodonium (DPI) and apocynin lower whole body and blood glucose levels and improve diabetes when administered to rodents. Skeletal muscle has an important role in managing glucose homeostasis and we have used L6 cells, C(2)C(12) cells and primary muscle cells as model systems to investigate whether these drugs regulate glucose uptake in skeletal muscle cells. The data presented in this study show that apocynin does not affect glucose uptake in skeletal muscle cells in culture. Tat gp91ds, a chimeric peptide that inhibits NADPH oxidase activity, also failed to affect glucose uptake and we found no significant evidence of NADPH oxidase (subunits tested were Nox4, p22phox, gp91phox and p47phox mRNA) in skeletal muscle cells in culture. However, DPI increases basal and insulin-stimulated glucose uptake in L6 cells, C(2)C(12) cells and primary muscle cells. Detailed studies on L6 cells demonstrate that the increase of glucose uptake is via a mechanism independent of phosphoinositide-3 kinase (PI3K)/Akt but dependent on AMP-activated protein kinase (AMPK). We postulate that DPI through inhibition of mitochondrial complex 1 and decreases in oxygen consumption, leading to decreases of ATP and activation of AMPK, stimulates glucose uptake in skeletal muscle cells.
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PMID:Diphenylene iodonium stimulates glucose uptake in skeletal muscle cells through mitochondrial complex I inhibition and activation of AMP-activated protein kinase. 1739 17


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