Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The potassium homeostatic system is very tightly regulated. Recent studies have shed light on the sensing and molecular mechanisms responsible for this tight control. In addition to classic feedback regulation mediated by a rise in extracellular fluid (ECF) [K(+)], there is evidence for a feedforward mechanism: Dietary K(+) intake is sensed in the gut, and an unidentified gut factor is activated to stimulate renal K(+) excretion. This pathway may explain renal and extrarenal responses to altered K(+) intake that occur independently of changes in ECF [K(+)]. Mechanisms for conserving ECF K(+) during fasting or K(+) deprivation have been described: Kidney NADPH oxidase activation initiates a cascade that provokes the retraction of K(+) channels from the cell membrane, and muscle becomes resistant to insulin stimulation of cellular K(+) uptake. How these mechanisms are triggered by K(+) deprivation remains unclear. Cellular AMP kinase-dependent protein kinase activity provokes the acute transfer of K(+) from the ECF to the ICF, which may be important in exercise or ischemia. These recent advances may shed light on the beneficial effects of a high-K(+) diet for the cardiovascular system.
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PMID:Recent advances in understanding integrative control of potassium homeostasis. 1875 36

Diabetes activates atherogenesis and macrophage foam cell formation. This study's goal was to determine whether insulin counteracts diabetes-induced macrophage foam cell formation, as well as to determine transcriptional mechanisms involved in this effect.Insulin injection to diabetic mice reduced macrophage lipid peroxides levels, Ox-LDL uptake, and CD36 mRNA levels by 40%, 29%, and by 41% respectively, compared to age-matched untreated diabetic mice. These results were further assessed using an in vitro system. Addition of insulin to glucose-enriched cells led to a significant decrease in cellular lipid peroxidation by 43% compared to cells incubated with high concentrations of glucose with no insulin. This effect was correlated with a reduction in NADPH oxidase activity.Macrophage cholesterol biosynthesis was then studied in cells from diabetic mice treated with insulin and in glucose-enriched macrophages incubated with insulin. Insulin treatment of diabetic mice significantly reduced macrophage cholesterol biosynthesis, HMG-CoA reductase mRNA expression, and protein expression by 81%, 54%, and 31% respectively, compared to macrophages isolated from nontreated diabetic mice. Similarly, insulin incubation with glucose-enriched macrophages significantly reduced macrophage cholesterol biosynthesis, HMG-CoA reductase mRNA expression, and protein expression by 84%, 42%, and 18%, respectively, compared to macrophages incubated with high glucose but without insulin. These effects were mediated by glucose and insulin ability to regulate the transcription factor SREBP-1. Whereas glucose upregulated SREBP-1 expression and maturation, insulin blocked SREBP1 cleavage, leading to reduced mature form of the transcription factor in the nucleus.In conclusion, this study presents important novel insights on the events connecting diabetes and glucose stimulation of macrophage foam cell formation leading to atherosclerosis. Most important, the inhibitory effects of insulin on diabetes-mediated (and high glucose-induced) increased cholesterol synthesis were shown to involve modulation of SREBP-1 expression and its maturation.
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PMID:High glucose concentration increases macrophage cholesterol biosynthesis in diabetes through activation of the sterol regulatory element binding protein 1 (SREBP1): inhibitory effect of insulin. 1879 64

Diabetes is characterized by elevated fasting blood glucose (FBG) resulting from improper insulin regulation and/or insulin resistance. Herein we used female C57BL/6J mouse models for type 1 diabetes (streptozotocin [STZ] treatment) and type 2 diabetes (high-fat diet) to examine the ability of 4b,5,9b,10-tetrahydroindeno[1,2-b]indole (THII) to intervene in the progression of diabetes. THII (100 microM in drinking water) significantly diminished and partially reversed the increase in FBG levels produced by STZ. After 10 weeks on a high-fat diet, mice had normal FBG levels, but exhibited fasting hyperinsulemia and loss of glucose tolerance. THII significantly diminished these changes in glucose and insulin. In isolated liver mitochondria, THII inhibited succinate-dependent H(2)O(2) production, while in white adipose tissue, THII inhibited NADPH oxidase-mediated H(2)O(2) production and lipid peroxidation. Without intervention, such oxidative processes might otherwise promote diabetogenesis via inflammatory pathways. THII also increased O(2) consumption and lowered respiratory quotient (CO(2) produced/O(2) consumed) in vivo, indicating a greater utilization of fat for metabolic fuel. Increased metabolic utilization of fat correlated with a decrease in the rate of body weight gain in THII-treated mice fed the high-fat diet. We conclude that THII may retard the progression of diabetes via multiple pathways, including the inhibition of oxidative and inflammatory pathways.
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PMID:Tetrahydroindenoindole inhibits the progression of diabetes in mice. 1882 64

Essential hypertension is an insulin resistant state. Early insulin signaling steps are impaired in essential hypertension and a large body of data suggests that there is a crosstalk at multiple levels between the signal transduction pathways that mediate insulin and angiotensin II actions. At the extracellular level the angiotensin converting enzyme (ACE) regulates the synthesis of angiotensin II and bradykinin that is a powerful vasodilator. At early intracellular level angiotensin II acts on JAK-2/IRS1-IRS2/PI3-kinase, JNK and ERK to phosphorylate serine residues of key elements of insulin signaling pathway therefore inhibiting signaling by the insulin receptor. On another level angiotensin II inhibits the insulin signaling inducing the regulatory protein SOCS 3. Angiotensin II acting through the AT1 receptor can inhibit insulin-induced nitric oxide (NO) production by activating ERK 1/2 and JNK and enhances the activity of NADPH oxidase that leads to an increased reactive oxygen species generation. From the clinical standpoint, the inhibition of the renin angiotensin system improves insulin sensitivity and decreases the incidence of Type 2 Diabetes Mellitus (T2DM). This might represent an alternative approach to prevent type 2 diabetes in patients with hypertension and metabolic syndrome, (i.e. insulin resistant patients). This review will discuss: a) the molecular mechanisms of the crosstalk between the insulin and angiotensin II signaling systems b) the results of clinical studies employing drugs targeting the renin-angiotensin II-aldosterone systems and their role in glucose metabolism and diabetes prevention.
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PMID:The crosstalk between insulin and renin-angiotensin-aldosterone signaling systems and its effect on glucose metabolism and diabetes prevention. 1885 18

Alterations of hepatocyte volume induced by either anisoosmotic environments or under the influence of hormones, concentrative amino acid uptake and oxidative stress are now recognized as an independent signal which contributes to the regulation of liver cell function and gene expression. Several long-known but mechanistically poorly understood effects of amino acids, which could not be related to their metabolism, such as the stimulation of glycogen synthesis or the inhibition of proteolysis are due to their effects on hepatocyte hydration, because they are quantitatively mimicked by swelling the cells in hypoosmotic media to the extent as the amino acids do. Likewise, transmembrane ion movements under the influence of hormones are an integral part of hormonal signal transduction mechanisms with alterations of cellular hydration acting as another "second messenger" of hormone action. Integrins act as osmosensors for hepatocyte swelling and trigger activation of mitogen- activated protein kinase systems as osmosignaling cascades towards choleresis and autophagy inhibition. On the contrary, hepatocyte shrinkage triggers endosomal acidification as a signal for a ceramide-dependent activation of NADPH oxidase isoenzymes, which results in an oxidative stress signal with proapoptotic effects. Disturbances of osmosignaling and osmosensing are involved in a variety of pathophysiological conditions such as insulin resistance, protein catabolic states and cholestatic liver injury. This article briefly summarizes some aspects of our own work on osmosignaling and osmosensing; for indepth surveys the reader is refered to recent reviews [1-6].
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PMID:Osmosensing and osmosignaling in the liver. 1899 70

Beneficial effects of an antioxidant (N-acetyl-L-cysteine, NAC) and an angiotensin I-converting enzyme (ACE) inhibitor (ramipril) were assessed in a rat model of insulin resistance induced by 10% glucose feeding for 20 weeks. Treatments with NAC (2 g/kg per day) and ramipril (1 mg/kg per day) were initiated at 16 weeks in the drinking fluid. Systolic blood pressure, plasma levels of insulin and glucose, and insulin resistance were significantly higher in rats treated with glucose for 20 weeks. This was associated with a higher production of superoxide anion and NADPH oxidase activity in aorta and liver and with a marked reduction in protein expression of skeletal muscle insulin receptor substrate-1 (IRS-1) in the gastrocnemius muscle. NAC prevented all these alterations. Although ramipril also reversed high blood pressure, it had a lesser effect on insulin resistance (including IRS-1) and blocked superoxide anion production only in aorta. Ramipril, in contrast to NAC, did not reduce NADPH oxidase activity in aorta and liver or plasma levels of 4-hydroxynonenal and malondialdehyde. Results suggest that the inhibition of the oxidative stress in hypertensive and insulin-resistant states contributes to the therapeutic effects of NAC and ramipril. Whereas NAC exerts effective antioxidant activity in multiple tissues, ramipril appears to preferentially target the vasculature.
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PMID:Comparative effects of N-acetyl-L-cysteine and ramipril on arterial hypertension, insulin resistance, and oxidative stress in chronically glucose-fed rats. 1901 70

Skeletal muscle is one of the main physiological targets of insulin, a hormone that triggers a complex signaling cascade and that enhances the production of reactive oxygen species (ROS) in different cell types. ROS, currently considered second messengers, produce redox modifications in proteins such as ion channels that induce changes in their functional properties. In myotubes, insulin also enhances calcium release from intracellular stores. In this work, we studied in myotubes whether insulin stimulated ROS production and investigated the mechanisms underlying the insulin-dependent calcium increase: in particular, whether the late phase of the Ca2+ increase induced by insulin required ROS. We found that insulin stimulated ROS production, as detected with the probe 2',7'-dichlorofluorescein diacetate (CM-H2DCFDA). We used the translocation of p47phox from the cytoplasm to the plasma membrane as a marker of the activation of NADPH oxidase. Insulin-stimulated ROS generation was suppressed by the NADPH oxidase inhibitor apocynin and by small interfering RNA against p47phox, a regulatory NADPH oxidase subunit. Additionally, both protein kinase C and phosphatidylinositol 3-kinase are presumably involved in insulin-induced ROS generation because bisindolylmaleimide, a nonspecific protein kinase C inhibitor, and LY290042, an inhibitor of phosphatidylinositol 3-kinase, inhibited this increase. Bisindolylmaleimide, LY290042, apocynin, small interfering RNA against p47phox, and two drugs that interfere with inositol 1,4,5-trisphosphate-mediated Ca2+ release, xestospongin C and U73122, inhibited the intracellular Ca2+ increase produced by insulin. These combined results strongly suggest that insulin induces ROS generation trough NADPH activation and that this ROS increase is required for the intracellular Ca2+ rise mediated by inositol 1,4,5-trisphosphate receptors.
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PMID:NADPH oxidase and hydrogen peroxide mediate insulin-induced calcium increase in skeletal muscle cells. 1902 99

Studies reported the effects of polyphenols but not for grape polyphenols towards obesity. We analysed the effects of a polyphenolic grape seed extract (GSE) on obesity and oxidative stress in hamsters receiving a high-fat diet (HFD). Three groups of hamsters received a standard diet (STD), or a HFD plus a daily gavage with water (Control, HFD) or a solution of GSE (HFD + GSE) for 12 wk. Plasma glucose, triglycerides (TG), insulin, leptin and adiponectin were measured. Oxidative stress was assessed by cardiac production of superoxide anion and NAD(P)H oxidase expression. After 12 wk, HFD increased abdominal fat as compared with standards. GSE avoided this feature. HFD led to higher plasma glucose, TG, insulin and greater insulin resistance (HOMA-IR) values. GSE prevented in part these effects, reducing insulinemia and leptinemia by 16.5 and 45%, respectively, whereas adiponectin level increased by 61% compared with obese controls. GSE lowered glycemia and HOMA-IR and strongly prevented cardiac production of superoxide by 74% and NAD(P)H oxidase expression by 30%. This is the first time that chronic consumption of grape phenolics is shown to reduce obesity development and related metabolic pathways including adipokine secretion and oxidative stress.
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PMID:Chardonnay grape seed procyanidin extract supplementation prevents high-fat diet-induced obesity in hamsters by improving adipokine imbalance and oxidative stress markers. 1903 54

It has been shown that NADPH oxidase plays a role in oxidative stress which has been involved in the development of metabolic syndrome. The -930A/G polymorphism of the CYBA gene (that codes p22phox, a major component of the NADPH oxidase) has been associated with human hypertension and with a reduction in NADPH oxidase activity. In this work, we have examined the influence of the -930A/G polymorphism on obesity risk and insulin resistance in a case-control study of Spanish subjects (n=313). In the obese group (n=159), there was a statistically significant association between the GG genotype of the -930A/G polymorphism of the CYBA gene and fasting insulin levels and HOMA index. This outcome agrees with previous findings concerning functional analyses of this polymorphism and reinforces the hypothesis that insulin resistance is associated with oxidative stress. In conclusion, a protective effect in carriers of the -930A/G polymorphism of the p22phox gene against insulin resistance in a population of Spanish obese adults has been found.
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PMID:G allele of the -930A>G polymorphism of the CYBA gene is associated with insulin resistance in obese subjects. 1904 82

Angiotensin II (Ang II) controls blood pressure, electrolyte balance, cell growth and vascular remodeling. Ang II activates NAD(P)H oxidase in several tissues with important function in the control of insulin secretion. Considering the concomitant occurrence of hypertension, insulin resistance and pancreatic B cell secretion impairment in the development of type II diabetes the aim of the present study was to evaluate the effect of ANG II on NAD(P)H oxidase activation in isolated pancreatic islets. We found that ANGII-induced superoxide generation via NAD(P)H oxidase activation and increased protein and mRNA levels of NAD(P)H oxidase subunits (p47(PHOX) and gp91(PHOX)).
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PMID:Angiotensin II induces superoxide generation via NAD(P)H oxidase activation in isolated rat pancreatic islets. 1908 Oct 82


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