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)

Physiological and pathophysiological conditions often affect the expression of drug metabolizing enzymes such as cytochromes P450 (P450s). Diabetes is one such factor and it is of great interest to understand its effects on drug metabolism, since diabetic patients generally have increased need for pharmacotherapy. We have recently reported the coordinated reduction of CYP2B1/2 and their transcriptional regulator constitutive androstane receptor (CAR), a member of the nuclear receptor superfamily, in the liver of genetically obese/diabetic Zucker fatty rats (Xiong, H., Yoshinari, K., et al., Drug Metab. Dispos., 30, 918-923, 2002). In this study, we investigated the expression of P450s and liver-enriched nuclear receptors in the liver of genetically diabetic db/db mice. Surprisingly, both CYP2B10 and CAR levels were increased in db/db mice. CYP4A expression was also increased at both mRNA and protein levels in db/db mice, while those of peroxisome proliferator-activated receptor alpha, a key regulator for the transcriptional activation of CYP4As, were comparable to those in age-matched C57BL/6 mice. Our results demonstrate that db/db mice and Zucker fatty rats exhibit different expression profiles of P450s and nuclear receptors despite their similar characteristics for obesity and diabetes resulting from a defect in the leptin signaling pathway.
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PMID:Changes in the expression of cytochromes P450 and nuclear receptors in the liver of genetically diabetic db/db mice. 1688 Jun 18

Nitric oxide is a diatomic gaseous molecule with unpaired electron in the molecule. Physical properties such as solubility, diffusibility and half-life decide the chemical reactivity of nitric oxide. Nitric oxide is the unstable free radical in vessels, immune system and central nervous system. The reactivity of nitric oxide under physiological and pathological conditions depends upon its concentration and site of production. Nitric oxide is thought to play a role in many pathological situations: septic shock, cardiovascular diseases, arthritis, diabetes, multiple sclerosis, asthma, and hypertension. Nitric oxide synthase is a self-sufficient flavohemoprotein capable of producing nitric oxide from L-arginine by two successive monooxygenation steps. Although the N-terminal heme domain functionally resembles cytochromes P450, no structural similarities exist between cytochrome P450 and nitric oxide synthases heme domains. The C-terminal domain of nitric oxide synthases containing flavin adenine dinucleotide and flavin mononucleotide as cofactors exhibits a high degree of sequence similarity with NADPH-cytocrome P450 reductase. The reductase domains serve as an intermediary for the transfer of electrons from NADPH for the catalytic reaction. The connecting domain between the oxygenase and the reductase domains of nitric oxide synthase isoforms binds calmodulin in the presence of calcium. The binding of calmodulin to all nitric oxide synthase isoforms is obligatory for the production of nitric oxide. At the same time, the presence of one or more phosphorylation sites in nitric oxide synthase puts them among the kinase-mediated signaling pathways. This also means that nitric oxide synthases are regulated indirectly by the events that regulate kinases. This field of research of nitric oxide synthase regulation has become one of the most actively pursued and much has been learned from basic biochemical mechanisms to physiological processes and to medical applications, but many more questions still remain to be answered.
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PMID:[Nitric oxide synthase, typical flavohemoproteins and their complicated enzymology]. 1692 79

Troglitazone (TGZ), the prototype 2,4-thiazolidinedione antidiabetic agent, is associated with hepatotoxicity in patients with Type 2 diabetes. Although the mechanism of toxicity has not been established, alterations in the clearance of TGZ from in-vitro hepatocyte cultures through metabolic conjugation reactions are believed to modulate the toxicity of the compound. In this study, the metabolism of TGZ in freshly isolated hepatocytes from the fat-fed streptozotocin-treated rat model of Type 2 diabetes is described. Biochemical parameters such as cellular reduced glutathione content, content of cytochromes P450 and b5, and the expression of glutathione-S-transferase alpha (subunits Ya and Yc2) were not affected by the induced diabetes. TGZ was metabolized primarily to a sulfonate, a quinone and a glucuronide in both control and experimentally diabetic animals. However, metabolism after induction of diabetes was characterized by a moderate increase in sulfation, a decrease in the elimination half-life of TGZ and the absence of the minor metabolites of TGZ, notably the glutathione adduct of the putative reactive intermediate (m/z = 747 (M + H)+; m/z = 745 (M - H)-).
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PMID:Metabolism of troglitazone in hepatocytes isolated from experimentally induced diabetic rats. 1703 59

Muraglitazar (Pargluva), a dual alpha/gamma peroxisome proliferator-activated receptor activator, has both glucose- and lipid-lowering effects in animal models and in patients with diabetes. The human major primary metabolic pathways of muraglitazar include acylglucuronidation, aliphatic/aryl hydroxylation, and O-demethylation. This study describes the identification of human cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) enzymes involved in the in vitro metabolism of muraglitazar. [(14)C]Muraglitazar was metabolized by cDNA-expressed CYP2C8, 2C9, 2C19, 2D6, and 3A4, but to a very minimal extent by CYP1A2, 2A6, 2B6, 2C18, 2E1, and 3A5. Inhibition of the in vitro metabolism of muraglitazar in human liver microsomes, at a clinically efficacious concentration, by chemical inhibitors and monoclonal antibodies further supported involvement of CYP2C8, 2C9, 2C19, 2D6, and 3A4 in its oxidation. A combination of intrinsic clearance (V(max)/K(m)) and relative concentrations of each P450 enzyme in the human liver was used to predict the contribution of CYP2C8, 2C9, 2C19, 2D6, and 3A4 to the formation of each primary oxidative metabolite and to the overall oxidative metabolism of muraglitazar. Glucuronidation of [(14)C]muraglitazar was catalyzed by cDNA-expressed UGT1A1, 1A3, and 1A9, but not by UGT1A6, 1A8, 1A10, 2B4, 2B7, and 2B15. The K(m) values for muraglitazar glucuronidation by the three active UGT enzymes were similar (2-4 muM). In summary, muraglitazar was metabolized by multiple P450 and UGT enzymes to form multiple metabolites. This characteristic predicts a low potential for the alteration of the pharmacokinetic parameters of muraglitazar via polymorphic drug metabolism enzymes responsible for clearance of the compound or by coadministration of drugs that inhibit or induce relevant metabolic enzymes.
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PMID:Involvement of multiple cytochrome P450 and UDP-glucuronosyltransferase enzymes in the in vitro metabolism of muraglitazar. 1706 78

Endogenous factors, including hormones, growth factors and cytokines, play an important role in the regulation of hepatic drug metabolizing enzyme expression in both physiological and pathophysiological conditions. Diabetes, fasting, obesity, protein-calorie malnutrition and long-term alcohol consumption produce changes in hepatic drug metabolizing enzyme gene and protein expression. This difference in expression alters the metabolism of xenobiotics, including procarcinogens, carcinogens, toxicants and therapeutic agents, potentially impacting the efficacy and safety of therapeutic agents, and/or resulting in drug-drug interactions. Although the mechanisms by which xenobiotics regulate drug metabolizing enzymes have been studied intensively, less is known regarding the cellular signaling pathways and components which regulate drug metabolizing enzyme gene and protein expression in response to hormones and cytokines. Recent findings, however, have revealed that several cellular signaling pathways are involved in hormone- and growth factor-mediated regulation of drug metabolizing enzymes. Our laboratory has reported that insulin and growth factors regulate drug metabolizing enzyme gene and protein expression, including cytochromes P450 (CYP), glutathione S-transferases (GST) and microsomal epoxide hydrolase (mEH), through receptors which are members of the large receptor tyrosine kinase (RTK) family, and by downstream effectors such as phosphatidylinositol 3-kinase, mitogen activated protein kinase (MAPK), Akt/protein kinase B (PKB), mammalian target of rapamycin (mTOR), and the p70 ribosomal protein S6 kinase (p70S6 kinase). Here, we review current knowledge of the signaling pathways implicated in regulation of drug metabolizing enzyme gene and protein expression in response to insulin and growth factors, with the goal of increasing our understanding of how disease affects these signaling pathways, components, and ultimately gene expression and translational control.
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PMID:The role of intracellular signaling in insulin-mediated regulation of drug metabolizing enzyme gene and protein expression. 1709 48

The phase I enzyme known as cytochrome P450 1B1 (CYP1B1) is involved in the metabolism of many endogenous and exogenous compounds, including carcinogens. CYP1B1 is overexpressed in a wide variety of human diseases ranging from diabetes to malignancies, such as invasive breast cancer. Because of its microsomal location in the cell, CYP1B1 could not be measured directly by existing methods but only assessed indirectly via the determination of the catalytic products. We report here a rapid, sensitive piezoimmunosensor for detection of CYP1B1 using single-chain fragment variable antibodies (scFv) as recognition elements and a quartz crystal microbalance (QCM) as the transducer. Three anti-CYP1B1 scFvs (designated B-66, D-23, and L-21) were biotinylated and used to capture and specifically detect CYP1B1 from samples in solution. ScFvs are smaller than most commonly used antibodies and can be coated onto QCM surfaces at much higher density to improve sensor sensitivity and specificity. The scFv-QCM biosensors showed excellent sensitivity (detection limit, 2.2 +/- 0.9 nM) and specificity with a dissociation constant K(d) = (1.54 +/- 0.59) x 10(-7) M. CYP1B1 were quantitatively detected in normal and malignant cell lysates (e.g., human T47D breast cancer cell microsomes). Results demonstrate that an anti-CYP1B1 scFv-QCM immunosensor could be used to detect P450 enzymes in biological samples.
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PMID:Recombinant antibody piezoimmunosensors for the detection of cytochrome P450 1B1. 1729 25

Dehydroepiandrosterone (DHEA), the major precursor of androgens and estrogens, has several beneficial effects on the immune system, on memory function, and in modulating the effects of diabetes, obesity, and chemical carcinogenesis. Treatment of rats with DHEA influences expression of cytochrome P450 (P450) genes, including peroxisome proliferator-activated receptor alpha (PPAR alpha)- and pregnane X receptor (PXR)-mediated induction of CYP4As and CYP3A23, and suppression of CYP2C11. DHEA treatment elevated the expression and activities of CYP3A4, CYP2C9, CYP2C19, and CYP2B6 in primary cultures of human hepatocytes. Induction of CYP3A4 in human hepatocytes was consistent with studies in rats, but induction of CYP2Cs was unexpected. The role of PXR in this response was studied in transient transfection assays. DHEA activated hPXR in a concentration-dependent manner. Because CYP2B6 induction by DHEA in human hepatocytes might involve either PXR or constitutive androstane receptor (CAR) activation, we performed experiments in primary hepatocytes from CAR knockout mice and observed that CAR was required for maximal induction of Cyp2b10 by DHEA. Furthermore, CAR-mediated Cyp2b10 induction by DHEA was inhibited by the inverse agonist of CAR, androstanol (5 alpha-androstan-3 alpha-ol). Further evidence for CAR activation was provided by cytoplasmic/nuclear transfer of CAR upon DHEA treatment. Elucidation of CAR activation and subsequent induction of CYP2B6 by DHEA presented an additional mechanism by which the sterol can modify the expression of P450s. The effect of DHEA on the activation of the xenosensors PPAR alpha, PXR, and CAR, and the consequent potential for adverse drug/toxicant interactions should be considered in humans treated with this nutriceutical agent.
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PMID:Dehydroepiandrosterone induces human CYP2B6 through the constitutive androstane receptor. 1759 76

The cytochrome P450 system plays a key role in the metabolism of endogenous and exogenous compounds. The system is distributed widely in body tissues, with the highest concentration of the enzymes found in liver hepatocytes. Extrahepatic expression of the P450 system has been documented in the lung, pancreas and kidney, and the enzymes are induced by many disease states, including diabetes mellitus and cancer. Little attention has been paid to the expression and inducibility of the system in peripheral blood lymphocytes. In this study, specific P450 inducers are administered in vivo to male Wistar rats. The expression and in vivo induction of the P450 isoforms CYP2B, CYP2E, CYP3A and CYP4A in liver and lymphocyte samples is determined using Western blot analysis. Following in vivo induction, the lymphocyte P450 proteins showed an average three-fold increase in expression (0.003-0.005 microg P450/microg microsomal protein), compared to the control lymphocyte samples. Expression in the induced lymphocyte samples was up to 11-fold lower than that in the induced liver samples, as expected. These results indicate that lymphocytes may provide a relatively simple method by which to monitor the P450 profile in human subjects.
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PMID:Lymphocyte cytochrome P450 expression: inducibility studies in male Wistar rats. 1847 87

Ritonavir and atazanavir (ATZ) are protease inhibitors (PI) that inhibit the P450 3A4 cytochrome. They are used together to boost ATZ levels and reduce pill burden in human immunodeficiency virus infection, but association with medications metabolized by this cytochrome can cause serious adverse effects. Several cases of Cushing's syndrome have been reported when patients received inhaled therapy with fluticasone for asthma, sometimes complicated by secondary adrenal failure after stopping fluticasone. We report a case of Cushing's syndrome associated with onset of diabetes mellitus in a patient treated with boosted PI (ATZ and ritonavir) for HIV 2 (CD4360/ml). Asthma was treated with inhaled fluticasone 1500mug/day for several months that was stopped at admission. A few days later, typical secondary adrenal failure developed and was confirmed by dosage of cortisol and ACTH, both low. Hydrocortisone replacement treatment resulted in rapid improvement of symptoms. Diabetes was initially treated with insulin then sulfonyluraes, but repeated hypoglycemias lead to diet alone. Physicians should be aware of the potential danger of the association of "boosted" IP and some kind of inhaled corticotherapy.
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PMID:[Iatrogenic Cushing's syndrome, diabetes mellitus and secondary adrenal failure in a human immunodeficiency virus patient treated with ritonavir boosted atazanavir and fluticasone]. 1941 10

The cytochrome P450 monooxygenase system (CYP) is a multigene superfamily of heme-thiolate enzymes, which are important in the metabolism of foreign and endogenous compounds. Genetic variations, drug interactions, or pathophysiological factors can lead to reduced, absent, or increased enzymatic activity. This altered CYP activity greatly influences an individual's response to therapeutic treatment. What is not known is the impact of these changes on the many functional roles of CYP in physiological and pathophysiological processes of the heart. Many extrahepatic tissues, like heart, contain active P450 enzymes but lack information regarding their role in cellular injury or homeostasis. Much of our current knowledge about cardiac CYP has been limited to studies investigating the role of fatty acid metabolites in heart. Traditional risk factors including diabetes, smoking, and hypertension have well established links to cardiovascular disease. And new evidence strongly suggests exposure to chemicals and other environmental agents has a profound impact on the cardiovascular system. These risk factors can independently affect the expression and activity of CYP enzymes. Therefore, altered CYP activity is important from a detoxification as well as a bioactivation perspective. Considering CYP, interactions are greatly dependent on inherited differences or acquired changes in enzyme activity further research into their potential impact on pathogenesis, risk assessment, and therapy of heart disease is warranted. This review explores the expression of CYP isoforms, their functional roles, and the effects of genetic variation in the heart.
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PMID:Cytochrome P450 enzymes and the heart. 1978 9


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