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Elnagdy M, Wang Y, Rodriguez W, Zhang J, Bauer P, Wilkey DW, Merchant M, Pan J, Farooqui Z, Cannon R, Rai S, Maldonado C, Barve S, McClain CJ, Gobejishvili L. Increased expression of phosphodiesterase 4 in activated hepatic stellate cells promotes cytoskeleton remodeling and cell migration. J Pathol 2023; 261:361-371. [PMID: 37735782 PMCID: PMC10653049 DOI: 10.1002/path.6194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 06/24/2023] [Accepted: 07/30/2023] [Indexed: 09/23/2023]
Abstract
Activation and transdifferentiation of hepatic stellate cells (HSC) into migratory myofibroblasts is a key process in liver fibrogenesis. Cell migration requires an active remodeling of the cytoskeleton, which is a tightly regulated process coordinated by Rho-specific guanine nucleotide exchange factors (GEFs) and the Rho family of small GTPases. Rho-associated kinase (ROCK) promotes assembly of focal adhesions and actin stress fibers by regulating cytoskeleton organization. GEF exchange protein directly activated by cAMP 1 (EPAC1) has been implicated in modulating TGFβ1 and Rho signaling; however, its role in HSC migration has never been examined. The aim of this study was to evaluate the role of cAMP-degrading phosphodiesterase 4 (PDE4) enzymes in regulating EPAC1 signaling, HSC migration, and fibrogenesis. We show that PDE4 protein expression is increased in activated HSCs expressing alpha smooth muscle actin and active myosin light chain (MLC) in fibrotic tissues of human nonalcoholic steatohepatitis cirrhosis livers and mouse livers exposed to carbon tetrachloride. In human livers, TGFβ1 levels were highly correlated with PDE4 expression. TGFβ1 treatment of LX2 HSCs decreased levels of cAMP and EPAC1 and increased PDE4D expression. PDE4 specific inhibitor, rolipram, and an EPAC-specific agonist decreased TGFβ1-mediated cell migration in vitro. In vivo, targeted delivery of rolipram to the liver prevented fibrogenesis and collagen deposition and decreased the expression of several fibrosis-related genes, and HSC activation. Proteomic analysis of mouse liver tissues identified the regulation of actin cytoskeleton by the kinase effectors of Rho GTPases as a major pathway impacted by rolipram. Western blot analyses confirmed that PDE4 inhibition decreased active MLC and endothelin 1 levels, key proteins involved in cytoskeleton remodeling and contractility. The current study, for the first time, demonstrates that PDE4 enzymes are expressed in hepatic myofibroblasts and promote cytoskeleton remodeling and HSC migration. © 2023 The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Mohamed Elnagdy
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Kentucky, USA
| | - Yali Wang
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
| | - Walter Rodriguez
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
| | - JingWen Zhang
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
| | - Philip Bauer
- Department of Physiology, School of Medicine, University of Louisville, Kentucky, USA
- EndoProtech, Inc., Louisville, Kentucky, USA
| | - Daniel W. Wilkey
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
| | - Michael Merchant
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Kentucky, USA
| | - Jianmin Pan
- Department of Bioinformatics and Biostatistics, School of Public Health and Information Sciences, University of Louisville, Kentucky, USA
| | - Zainab Farooqui
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
| | - Robert Cannon
- Department of Surgery, School of Medicine, University of Louisville, Kentucky, USA
| | - Shesh Rai
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Bioinformatics and Biostatistics, School of Public Health and Information Sciences, University of Louisville, Kentucky, USA
| | - Claudio Maldonado
- Department of Physiology, School of Medicine, University of Louisville, Kentucky, USA
- EndoProtech, Inc., Louisville, Kentucky, USA
| | - Shirish Barve
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Kentucky, USA
| | - Craig J. McClain
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Kentucky, USA
- Robley Rex VA Medical Center, Louisville, Kentucky, USA
| | - Leila Gobejishvili
- University of Louisville Alcohol Research Center, University of Louisville, Kentucky, USA
- Hepatobiology and Toxicology Center, University of Louisville, Kentucky, USA
- Department of Medicine, School of Medicine, University of Louisville, Kentucky, USA
- Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, Kentucky, USA
- Department of Physiology, School of Medicine, University of Louisville, Kentucky, USA
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Kitano A, Norikura T, Matsui-Yuasa I, Shimakawa H, Kamezawa M, Kojima-Yuasa A. Phosphodiesterase 4 mRNA Level Suppression is Important for Extract of Black Carrot to Protect Against Hepatic Injury Induced by Ethanol. J Med Food 2022; 25:982-992. [PMID: 36201260 DOI: 10.1089/jmf.2021.k.0186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Excessive alcohol use often results in alcoholic liver disease (ALD). An early change in the liver due to excessive drinking is hepatic steatosis, which may ultimately progress to hepatitis, liver fibrosis, cirrhosis, and liver cancer. Among these debilitating processes, hepatic steatosis is reversible with the appropriate treatment. Therefore, it is important to find treatments and foods that reverse hepatic steatosis. Black carrot has antioxidant and anti-inflammatory effects. In this study, we examined the effectiveness of black carrot extract (BCE) on hepatic steatosis in in vivo and in vitro ethanol-induced liver injury models. For the in vivo experiments, serum aminotransferase activities enhanced by ethanol- and carbon tetrachloride were significantly suppressed by the BCE diet. Furthermore, morphological changes in the liver hepatic steatosis and fibrosis were observed in the in vivo ethanol-induced liver injury model, however, BCE feeding resulted in the recovery to an almost normal liver morphology. In the in vitro experiments, ethanol treatment induced reactive oxygen species (ROS) levels in hepatocytes at 9 h. Conversely, ROS production was suppressed to control levels and hepatic steatosis was suppressed when hepatocyte culture with ethanol were treated with BCE. Furthermore, we investigated enzyme activities, enzyme protein levels, and messenger RNA levels of alcohol dehydrogenase (ADH), cytochrome p450 2E1 (CYP2E1), and aldehyde dehydrogenase (ALDH) using enzyme assays, western blot, and quantitative reverse transcription-polymerase chain reaction analyses. We found that the activities of ADH, CYP2E1, and ALDH were regulated through the cAMP-PKA pathway at different levels, namely, translational, posttranslational, and transcriptional levels, respectively. The most interesting finding of this study is that BCE increases cAMP levels by suppressing the Pde4b mRNA and PDE4b protein levels in ethanol-treated hepatocytes, suggesting that BCE may prevent ALD.
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Affiliation(s)
- Atsuko Kitano
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, Japan
| | - Toshio Norikura
- Department of Nutrition, Aomori University of Health and Welfare, Aomori, Japan
| | - Isao Matsui-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, Japan
| | | | | | - Akiko Kojima-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, Osaka, Japan
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Role of Mitochondrial Cytochrome P450 2E1 in Healthy and Diseased Liver. Cells 2022; 11:cells11020288. [PMID: 35053404 PMCID: PMC8774478 DOI: 10.3390/cells11020288] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/05/2022] [Accepted: 01/11/2022] [Indexed: 12/14/2022] Open
Abstract
Cytochrome P450 2E1 (CYP2E1) is pivotal in hepatotoxicity induced by alcohol abuse and different xenobiotics. In this setting, CYP2E1 generates reactive metabolites inducing oxidative stress, mitochondrial dysfunction and cell death. In addition, this enzyme appears to play a role in the progression of obesity-related fatty liver to nonalcoholic steatohepatitis. Indeed, increased CYP2E1 activity in nonalcoholic fatty liver disease (NAFLD) is deemed to induce reactive oxygen species overproduction, which in turn triggers oxidative stress, necroinflammation and fibrosis. In 1997, Avadhani’s group reported for the first time the presence of CYP2E1 in rat liver mitochondria, and subsequent investigations by other groups confirmed that mitochondrial CYP2E1 (mtCYP2E1) could be found in different experimental models. In this review, we first recall the main features of CYP2E1 including its role in the biotransformation of endogenous and exogenous molecules, the regulation of its expression and activity and its involvement in different liver diseases. Then, we present the current knowledge on the physiological role of mtCYP2E1, its contribution to xenobiotic biotransformation as well as the mechanism and regulation of CYP2E1 targeting to mitochondria. Finally, we discuss experimental investigations suggesting that mtCYP2E1 could have a role in alcohol-associated liver disease, xenobiotic-induced hepatotoxicity and NAFLD.
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Wahlang B, McClain C, Barve S, Gobejishvili L. Role of cAMP and phosphodiesterase signaling in liver health and disease. Cell Signal 2018; 49:105-115. [PMID: 29902522 PMCID: PMC6445381 DOI: 10.1016/j.cellsig.2018.06.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/08/2018] [Accepted: 06/09/2018] [Indexed: 02/06/2023]
Abstract
Liver disease is a significant health problem worldwide with mortality reaching around 2 million deaths a year. Non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are the major causes of chronic liver disease. Pathologically, NAFLD and ALD share similar patterns of hepatic disorders ranging from simple steatosis to steatohepatitis, fibrosis and cirrhosis. It is becoming increasingly important to identify new pharmacological targets, given that there is no FDA-approved therapy yet for either NAFLD or ALD. Since the evolution of liver diseases is a multifactorial process, several mechanisms involving parenchymal and non-parenchymal hepatic cells contribute to the initiation and progression of liver pathologies. Moreover, certain protective molecular pathways become repressed during liver injury including signaling pathways such as the cyclic adenosine monophosphate (cAMP) pathway. cAMP, a key second messenger molecule, regulates various cellular functions including lipid metabolism, inflammation, cell differentiation and injury by affecting gene/protein expression and function. This review addresses the current understanding of the role of cAMP metabolism and consequent cAMP signaling pathway(s) in the context of liver health and disease. The cAMP pathway is extremely sophisticated and complex with specific cellular functions dictated by numerous factors such abundance, localization and degradation by phosphodiesterases (PDEs). Furthermore, because of the distinct yet divergent roles of both of its effector molecules, the cAMP pathway is extensively targeted in liver injury to modify its role from physiological to therapeutic, depending on the hepatic condition. This review also examines the behavior of the cAMP-dependent pathway in NAFLD, ALD and in other liver diseases and focuses on PDE inhibition as an excellent therapeutic target in these conditions.
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Affiliation(s)
- Banrida Wahlang
- University of Louisville Alcohol Research Center, School of Medicine, University of Louisville, KY, USA; Department of Medicine, School of Medicine, University of Louisville, KY, USA
| | - Craig McClain
- University of Louisville Alcohol Research Center, School of Medicine, University of Louisville, KY, USA; Department of Medicine, School of Medicine, University of Louisville, KY, USA; Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, KY, USA; Hepatobiology & Toxicology Center, School of Medicine, University of Louisville, KY, USA; Robley Rex Louisville VAMC, Louisville, KY, USA
| | - Shirish Barve
- University of Louisville Alcohol Research Center, School of Medicine, University of Louisville, KY, USA; Department of Medicine, School of Medicine, University of Louisville, KY, USA; Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, KY, USA; Hepatobiology & Toxicology Center, School of Medicine, University of Louisville, KY, USA
| | - Leila Gobejishvili
- University of Louisville Alcohol Research Center, School of Medicine, University of Louisville, KY, USA; Department of Medicine, School of Medicine, University of Louisville, KY, USA; Department of Pharmacology and Toxicology, School of Medicine, University of Louisville, KY, USA; Hepatobiology & Toxicology Center, School of Medicine, University of Louisville, KY, USA.
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Protective Effects of Hydrolyzed Nucleoproteins from Salmon Milt against Ethanol-Induced Liver Injury in Rats. Mar Drugs 2016; 14:md14120232. [PMID: 27999369 PMCID: PMC5192469 DOI: 10.3390/md14120232] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/04/2016] [Accepted: 12/15/2016] [Indexed: 12/12/2022] Open
Abstract
Dietary nucleotides play a role in maintaining the immune responses of both animals and humans. Oral administration of nucleic acids from salmon milt have physiological functions in the cellular metabolism, proliferation, differentiation, and apoptosis of human small intestinal epithelial cells. In this study, we examined the effects of DNA-rich nucleic acids prepared from salmon milt (DNSM) on the development of liver fibrosis in an in vivo ethanol-carbon tetrachloride cirrhosis model. Plasma aspartate transaminase and alanine transaminase were significantly less active in the DNSM-treated group than in the ethanol plus carbon tetrachloride (CCl₄)-treated group. Collagen accumulation in the liver and hepatic necrosis were observed histologically in ethanol plus CCl₄-treated rats; however, DNSM-treatment fully protected rats against ethanol plus CCl₄-induced liver fibrosis and necrosis. Furthermore, we examined whether DNSM had a preventive effect against alcohol-induced liver injury by regulating the cytochrome p450 2E1 (CYP2E1)-mediated oxidative stress pathway in an in vivo model. In this model, CYP2E1 activity in ethanol plus CCl₄-treated rats increased significantly, but DNSM-treatment suppressed the enzyme's activity and reduced intracellular thiobarbituric acid reactive substances (TBARS) levels. Furthermore, the hepatocytes treated with 100 mM ethanol induced an increase in cell death and were not restored to the control levels when treated with DNSM, suggesting that digestive products of DNSM are effective for the prevention of alcohol-induced liver injury. Deoxyadenosine suppressed the ethanol-induced increase in cell death and increased the activity of alcohol dehydrogenase. These results suggest that DNSM treatment represents a novel tool for the prevention of alcohol-induced liver injury.
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Michaut A, Le Guillou D, Moreau C, Bucher S, McGill MR, Martinais S, Gicquel T, Morel I, Robin MA, Jaeschke H, Fromenty B. A cellular model to study drug-induced liver injury in nonalcoholic fatty liver disease: Application to acetaminophen. Toxicol Appl Pharmacol 2015; 292:40-55. [PMID: 26739624 DOI: 10.1016/j.taap.2015.12.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 12/18/2015] [Accepted: 12/22/2015] [Indexed: 12/22/2022]
Abstract
Obesity and nonalcoholic fatty liver disease (NAFLD) can increase susceptibility to hepatotoxicity induced by some xenobiotics including drugs, but the involved mechanisms are poorly understood. For acetaminophen (APAP), a role of hepatic cytochrome P450 2E1 (CYP2E1) is suspected since the activity of this enzyme is consistently enhanced during NAFLD. The first aim of our study was to set up a cellular model of NAFLD characterized not only by triglyceride accumulation but also by higher CYP2E1 activity. To this end, human HepaRG cells were incubated for one week with stearic acid or oleic acid, in the presence of different concentrations of insulin. Although cellular triglycerides and the expression of lipid-responsive genes were similar with both fatty acids, CYP2E1 activity was significantly increased only by stearic acid. CYP2E1 activity was reduced by insulin and this effect was reproduced in cultured primary human hepatocytes. Next, APAP cytotoxicity was assessed in HepaRG cells with or without lipid accretion and CYP2E1 induction. Experiments with a large range of APAP concentrations showed that the loss of ATP and glutathione was almost always greater in the presence of stearic acid. In cells pretreated with the CYP2E1 inhibitor chlormethiazole, recovery of ATP was significantly higher in the presence of stearate with low (2.5mM) or high (20mM) concentrations of APAP. Levels of APAP-glucuronide were significantly enhanced by insulin. Hence, HepaRG cells can be used as a valuable model of NAFLD to unveil important metabolic and hormonal factors which can increase susceptibility to drug-induced hepatotoxicity.
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Affiliation(s)
- Anaïs Michaut
- INSERM, U991, Université de Rennes 1, Rennes, France
| | | | - Caroline Moreau
- INSERM, U991, Université de Rennes 1, Rennes, France; Service de Biochimie et Toxicologie, CHU Pontchaillou, Rennes, France
| | - Simon Bucher
- INSERM, U991, Université de Rennes 1, Rennes, France
| | - Mitchell R McGill
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | | | - Thomas Gicquel
- INSERM, U991, Université de Rennes 1, Rennes, France; Service de Biochimie et Toxicologie, CHU Pontchaillou, Rennes, France
| | - Isabelle Morel
- INSERM, U991, Université de Rennes 1, Rennes, France; Service de Biochimie et Toxicologie, CHU Pontchaillou, Rennes, France
| | | | - Hartmut Jaeschke
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
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Yamashita H, Goto M, Matsui-Yuasa I, Kojima-Yuasa A. Ecklonia cava Polyphenol Has a Protective Effect against Ethanol-Induced Liver Injury in a Cyclic AMP-Dependent Manner. Mar Drugs 2015; 13:3877-91. [PMID: 26096275 PMCID: PMC4483661 DOI: 10.3390/md13063877] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 05/23/2015] [Accepted: 06/09/2015] [Indexed: 02/07/2023] Open
Abstract
Previously, we showed that Ecklonia cava polyphenol (ECP) treatment suppressed ethanol-induced increases in hepatocyte death by scavenging intracellular reactive oxygen species (ROS) and maintaining intracellular glutathione levels. Here, we examined the effects of ECP on the activities of alcohol-metabolizing enzymes and their regulating mechanisms in ethanol-treated hepatocytes. Isolated hepatocytes were incubated with or without 100 mM ethanol. ECP was dissolved in dimethylsulfoxide. ECP was added to cultured cells that had been incubated with or without ethanol. The cells were incubated for 0-24 h. In cultured hepatocytes, the ECP treatment with ethanol inhibited cytochrome P450 2E1 (CYP2E1) expression and activity, which is related to the production of ROS when large quantities of ethanol are oxidized. On the other hand, ECP treatment with ethanol increased the activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase. These changes in activities of CYP2E1 and ADH were suppressed by treatment with H89, an inhibitor of protein kinase A. ECP treatment with ethanol enhanced cyclic AMP concentrations compared with those of control cells. ECP may be a candidate for preventing ethanol-induced liver injury via regulating alcohol metabolic enzymes in a cyclic AMP-dependent manner.
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Affiliation(s)
- Haruka Yamashita
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
| | - Mayu Goto
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
| | - Isao Matsui-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Akiko Kojima-Yuasa
- Department of Food and Human Health Sciences, Graduate School of Human Life Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
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Michaut A, Moreau C, Robin MA, Fromenty B. Acetaminophen-induced liver injury in obesity and nonalcoholic fatty liver disease. Liver Int 2014; 34:e171-9. [PMID: 24575957 DOI: 10.1111/liv.12514] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 02/10/2014] [Accepted: 02/23/2014] [Indexed: 12/14/2022]
Abstract
Although acetaminophen (APAP) is usually considered as a safe drug, this painkiller can lead to acute liver failure after overdoses. Moreover, there is evidence that the maximum recommended dosage can induce hepatic cytolysis in some individuals. Several predisposing factors appear to enhance the risk and severity of APAP-induced liver injury including chronic alcoholic liver disease and nonalcoholic fatty liver disease (NAFLD), which refers to a large spectrum of hepatic lesions linked to obesity. In contrast, obesity by itself does not seem to be associated with a higher risk of APAP-induced liver injury. Since 1987, seven studies dealt with APAP-induced hepatotoxicity in rodent models of NAFLD and five of them found that this liver disease was associated with higher APAP toxicity. Unfortunately, these studies did not unequivocally established the mechanism(s) whereby NAFLD could favour APAP hepatotoxicity, although some investigations suggested that pre-existent induction of hepatic cytochrome P450 2E1 (CYP2E1) could play a significant role by increasing the generation of N-acetyl-p-benzoquinone imine (NAPQI), the toxic metabolite of APAP. Moreover, pre-existent mitochondrial dysfunction associated with NAFLD could also be involved. In contrast, some investigations suggested that factors that could reduce the risk and severity of APAP hepatotoxicity in obesity and NAFLD include higher hepatic APAP glucuronidation, reduced CYP3A4 activity and increased volume of body distribution. Thus, the occurrence and the outcome of APAP-induced liver injury in an obese individual with NAFLD might depend on a delicate balance between metabolic factors that can be protective and others that favour large hepatic levels of NAPQI.
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Affiliation(s)
- Anaïs Michaut
- INSERM, U991, Université de Rennes 1, Rennes, France
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Dumais G, Iovu M, du Souich P. Inflammatory reactions and drug response: importance of cytochrome P450 and membrane transporters. Expert Rev Clin Pharmacol 2014; 1:627-47. [DOI: 10.1586/17512433.1.5.627] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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10
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Georgieva NI, Boysen G, Bordeerat N, Walker VE, Swenberg JA. Exposure-response of 1,2:3,4-diepoxybutane-specific N-terminal valine adducts in mice and rats after inhalation exposure to 1,3-butadiene. Toxicol Sci 2010; 115:322-9. [PMID: 20176624 PMCID: PMC2871755 DOI: 10.1093/toxsci/kfq060] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 02/17/2010] [Indexed: 12/25/2022] Open
Abstract
1,3-Butadiene (BD) is a known rodent and human carcinogen that is metabolized mainly by P450 2E1 to three epoxides, 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol. The individual epoxides vary up to 200-fold in their mutagenic potency, with DEB being the most mutagenic metabolite. It is important to understand the internal formation of the individual epoxides to assign the relative risk for each metabolite and to understand the molecular mechanisms responsible for extensive species differences in carcinogenicity. This study presents a comprehensive exposure-response for the formation of the DEB-specific N,N-(2,3-dihydroxy-1,4-butadiyl)valine (pyr-Val) in mice and rats. Using nano-ultra high pressure liquid chromatography-tandem-mass spectrometry allowed analysis of pyr-Val in mice and rats exposed to BD as low as 0.1 and 0.5 ppm BD, respectively, and demonstrated significant differences in the amounts and exposure-response of pyr-Val formation. Mice formed 10- to 60-fold more pyr-Val compared to rats at similar exposures. The formation of pyr-Val increased with exposures, and the formation was most efficient with regard to formation per parts per million BD at low exposures. While formation at higher exposures appeared linear in mice, in rats formation saturated at exposures > or = 200 ppm for 10 days. In rats, amounts of pyr-Val were lower after 20 days than after 10 days of exposure, suggesting that the lifespan of rat erythrocytes may be shortened following exposure to BD. This research supports the hypothesis that the lower susceptibility of rats to BD-induced carcinogenesis results from greatly reduced formation of DEB following exposure to BD.
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Affiliation(s)
| | - Gunnar Boysen
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | | | - Vernon E. Walker
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108
- Department of Pathology, University of Vermont, Burlington, Vermont 05405
| | - James A. Swenberg
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Catalano S, Barone I, Giordano C, Rizza P, Qi H, Gu G, Malivindi R, Bonofiglio D, Andò S. Rapid estradiol/ERalpha signaling enhances aromatase enzymatic activity in breast cancer cells. Mol Endocrinol 2009; 23:1634-45. [PMID: 19556341 DOI: 10.1210/me.2009-0039] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In situ estrogen production by aromatase conversion from androgens plays an important role in breast tumor promotion. Here, we show that 17beta-estradiol (E2) can rapidly enhance aromatase enzymatic activity through an increase of aromatase protein phosphorylation in breast cancer cell lines. In vivo labeling experiments and site-directed mutagenesis studies demonstrated that phosphorylation of the 361-tyrosine residue is crucial in the up-regulation of aromatase activity under E2 exposure. Our results demonstrated a direct involvement of nonreceptor tyrosine-kinase c-Src in E2-stimulated aromatase activity because inhibition of its signaling abrogated the up-regulatory effects induced by E2 on aromatase activity as well as phosphorylation of aromatase protein. In addition, from our data it emerges that aromatase is a target of cross talk between growth factor receptors and estrogen receptor alpha signaling. These findings show, for the first time, that tyrosine phosphorylation processes play a key role in the rapid changes induced by E2 in aromatase enzymatic activity, revealing the existence of a short nongenomic autocrine loop between E2 and aromatase in breast cancer cells.
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Affiliation(s)
- Stefania Catalano
- Department of Pharmaco-Biology, University of Calabria, Arcavacata di Rende (CS) 87030, Italy
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12
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Goggin M, Swenberg JA, Walker VE, Tretyakova N. Molecular dosimetry of 1,2,3,4-diepoxybutane-induced DNA-DNA cross-links in B6C3F1 mice and F344 rats exposed to 1,3-butadiene by inhalation. Cancer Res 2009; 69:2479-86. [PMID: 19276346 DOI: 10.1158/0008-5472.can-08-4152] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
1,3-Butadiene (BD) is an important industrial and environmental chemical classified as a human carcinogen based on epidemiologic studies in occupationally exposed workers and animal studies in laboratory rats and mice. BD is metabolically activated to three epoxides that can react with nucleophilic sites in biomolecules. Among these, 1,2,3,4-diepoxybutane (DEB) is considered the ultimate carcinogen due to its high genotoxicity and mutagenicity attributed to its ability to form DNA-DNA cross-links. Our laboratory has developed quantitative high-performance liquid chromatography-muESI(+)-tandem mass spectrometry methods for two DEB-specific DNA-DNA cross-links, 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) and 1-(guan-7-yl)-4-(aden-1-yl)-2,3-butanediol (N7G-N1A-BD). This report describes molecular dosimetry analysis of these adducts in tissues of B6C3F1 mice and F344 rats exposed to a range of BD concentrations (0-625 ppm). Much higher (4- to 10-fold) levels of DEB-DNA cross-links were observed in mice compared with rats exposed to the same BD concentrations. In both species, bis-N7G-BD levels were 1.5- to 4-fold higher in the liver than in other tissues examined. Interestingly, tissues of female animals exposed to BD contained higher concentrations of bis-N7G-BD adducts than tissues of male animals, which is in accord with previously reported differences in tumor incidence. The molecular dosimetry data presented herein suggest that species and gender differences observed in BD-induced cancer are directly related to differences in the extent of BD metabolism to DEB. Furthermore, a rat model of sensitivity to BD may be more appropriate than a mouse model for assessing human risk associated with BD exposure, because rats and humans seem to be similar with respect to DEB formation.
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Affiliation(s)
- Melissa Goggin
- Masonic Cancer Center and Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
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Wang Y, Liao M, Hoe N, Acharya P, Deng C, Krutchinsky AN, Correia MA. A role for protein phosphorylation in cytochrome P450 3A4 ubiquitin-dependent proteasomal degradation. J Biol Chem 2008; 284:5671-84. [PMID: 19095658 DOI: 10.1074/jbc.m806104200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochromes P450 (P450s) incur phosphorylation. Although the precise role of this post-translational modification is unclear, marking P450s for degradation is plausible. Indeed, we have found that after structural inactivation, CYP3A4, the major human liver P450, and its rat orthologs are phosphorylated during their ubiquitin-dependent proteasomal degradation. Peptide mapping coupled with mass spectrometric analyses of CYP3A4 phosphorylated in vitro by protein kinase C (PKC) previously identified two target sites, Thr(264) and Ser(420). We now document that liver cytosolic kinases additionally target Ser(478) as a major site. To determine whether such phosphorylation is relevant to in vivo CYP3A4 degradation, wild type and CYP3A4 with single, double, or triple Ala mutations of these residues were heterologously expressed in Saccharomyces cerevisiae pep4Delta strains. We found that relative to CYP3A4wt, its S478A mutant was significantly stabilized in these yeast, and this was greatly to markedly enhanced for its S478A/T264A, S478A/S420A, and S478A/T264A/S420A double and triple mutants. Similar relative S478A/T264A/S420A mutant stabilization was also observed in HEK293T cells. To determine whether phosphorylation enhances CYP3A4 degradation by enhancing its ubiquitination, CYP3A4 ubiquitination was examined in an in vitro UBC7/gp78-reconstituted system with and without cAMP-dependent protein kinase A and PKC, two liver cytosolic kinases involved in CYP3A4 phosphorylation. cAMP-dependent protein kinase A/PKC-mediated phosphorylation of CYP3A4wt but not its S478A/T264A/S420A mutant enhanced its ubiquitination in this system. Together, these findings indicate that phosphorylation of CYP3A4 Ser(478), Thr(264), and Ser(420) residues by cytosolic kinases is important both for its ubiquitination and proteasomal degradation and suggest a direct link between P450 phosphorylation, ubiquitination, and degradation.
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Affiliation(s)
- Yongqiang Wang
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94158, USA
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14
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Oesch-Bartlomowicz B, Oesch F. Role of cAMP in mediating AHR signaling. Biochem Pharmacol 2008; 77:627-41. [PMID: 19013136 DOI: 10.1016/j.bcp.2008.10.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 10/11/2008] [Accepted: 10/13/2008] [Indexed: 01/30/2023]
Abstract
Regulation of the nuclear import of many transcription factors represents a step in gene regulation which is crucial for a number of cellular processes. The aryl hydrocarbon receptor (AHR), a basic helix-loop-helix protein of the PAS (PER-ARNT-SIM) family of transcriptional regulators is a cytosol-associated and ligand-activated receptor. The environmental toxin dioxin binds with high affinity to AHR rendering it nuclear and leading to the activation of AHR sensitive genes. However, the fact, that the AHR mediates a large variety of physiological events without the involvement of any known exogenous ligand, including liver and vascular system development, maturation of the immune system, regulation of genes involved in cellular growth, cell differentiation and circadian rhythm, speaks for an important role of AHR in cell biology independent of the presence of an exogenous ligand. Different approaches were applied to study mechanism(s) which render AHR nuclear and design its function in absence of exogenous ligands. We found that AHR is sensitive to cAMP signaling mediated by cAMP-dependent protein kinase (PKA) which fundamentally differs from AHR signaling mediated by the exogenous ligand dioxin. It has been shown that PKA mediated signaling can be confined by compartmentalization of signaling components in microdomains conferring specificity to signaling by the ubiquitous second messenger cAMP. Moreover, A-kinase-anchoring proteins (AKAPs) and newly discovered cAMP receptors, Epac (exchange protein directly activated by cAMP), may give us a further chance to enter into new dimensions of cAMP signal transmissions that potentially may bring us closer to AHR physiology.
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15
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Ealey KN, Lu S, Archer MC. Development of aberrant crypt foci in the colons of ob/ob and db/db mice: evidence that leptin is not a promoter. Mol Carcinog 2008; 47:667-77. [PMID: 18240295 DOI: 10.1002/mc.20419] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Leptin is elevated in obesity and has been suggested to increase the risk of colorectal cancer (CRC), although the evidence is conflicting. The objective of this study was to compare the susceptibility to colon carcinogenesis of db/db mice that have highly elevated circulating leptin and leptin-deficient ob/ob mice, both of which are obese. Seven-week-old male ob/ob, db/db, and WT mice received 4 weekly i.p. injections of 5 mg/kg azoxymethane (AOM) and were killed 14 wk later for the analysis of putative preneoplastic aberrant crypt foci (ACF). There were no differences in ACF number or multiplicity between ob/ob and db/db mice. Leptin has been shown to induce CYP2E1, the main enzyme that activates AOM, but we observed no differences in hepatic CYP2E1 activity or colonic CYP2E1 protein levels between ob/ob and db/db mice. We also induced ACF with 2 oral doses 3 d apart of 30 mg/kg methylnitrosourea (MNU), a direct-acting carcinogen. There were no differences in ACF number or multiplicity between the two groups of obese animals 5 wk following the last dose of MNU. The colonic mucosa of db/db mice expressed significantly lower mRNA levels of ObRa, the predominant short form of the leptin receptor, compared to ob/ob mice, and following i.p. injection with 1 mg/kg recombinant mouse leptin, exhibited significantly reduced p44/42 pMAPK compared to saline-treated controls. These results show that ObRa is functionally active in the colons of db/db mice. We conclude that leptin does not play a significant role in ACF development.
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Affiliation(s)
- Kafi N Ealey
- Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Canada
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16
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Anji A, Kumari M. Supplementing the liquid alcohol diet with chow enhances alcohol intake in C57 BL/6 mice. Drug Alcohol Depend 2008; 97:86-93. [PMID: 18479843 PMCID: PMC3242077 DOI: 10.1016/j.drugalcdep.2008.03.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Revised: 03/14/2008] [Accepted: 03/16/2008] [Indexed: 11/16/2022]
Abstract
BACKGROUND Administration of alcohol-containing liquid diet is associated with body weight loss in rodents. AIM The aim of this study was to modify the alcohol-containing liquid diet paradigm to reduce the body weight loss in mice during the alcohol treatment period. METHODS Two sets of animals (Chow and No Chow groups) were exposed to chronic alcohol with a step-wise increase of alcohol in the diet. One set of control and alcohol exposed animals (Chow group) received chow during alcohol treatment. Food intake and body weight was measured every 24 h. Level of intoxication was determined by measuring blood alcohol levels. Alcohol dependence of mice was determined by handling-induced convulsions (HICs) scoring. Chronic alcohol-mediated effects on brain and liver were examined. RESULTS Body weight loss was attenuated in chronic alcohol exposed mice in Chow group as compared to No Chow group. Chow group mice consumed higher amounts of alcohol diet resulting in higher blood alcohol levels. Brain NMDA R1 protein levels and liver Cyp 2E1 levels were significantly enhanced in chronic alcohol exposed mice in Chow and No Chow groups suggesting that known medical consequences of alcohol are not interfered with in our modified alcohol treatment paradigm. HIC in Chow and No Chow group mice peaked between 3 and 5 h after alcohol withdrawal. However, the severity of alcohol withdrawal was greater in Chow group mice. CONCLUSIONS Supplementing alcohol diet with chow not only attenuated body weight loss associated with alcohol intake in mice but also resulted in higher consumption of alcohol diet and higher blood alcohol levels.
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Affiliation(s)
- Antje Anji
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA
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17
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Oesch-Bartlomowicz B, Oesch F. Phosphorylation of xenobiotic-metabolizing cytochromes P450. Anal Bioanal Chem 2008; 392:1085-92. [PMID: 18704375 DOI: 10.1007/s00216-008-2315-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 07/22/2008] [Accepted: 07/23/2008] [Indexed: 11/30/2022]
Abstract
The regulation of cytochromes P450 (CYPs) by induction mediated by xenobiotics is well known. Our team has discovered an additional important regulation of xenobiotic-metabolizing CYPs by phosphorylation. Individual CYPs are phosphorylated by different protein kinases, leading to CYP isoenzyme-selective changes in the metabolism of individual substrates and consequent profound changes in the control of mutagenic and cytotoxic metabolites. Some CYPs are phosphorylated by protein kinase C and some by the cyclic adenosine monophosphate (cAMP) dependent protein kinase A. We found that cAMP not only leads to drastic changes in the activity of individual CYPs, but also drastic changes in the nuclear localization of the CYP-related transcription factor Ah receptor (AHR). The consequences are very different from those of AHR nuclear translocation mediated by its classic ligands (such as dioxin and many polycyclic aromatic hydrocarbons) and may represent the long-sought physiological function of the AHR. The disturbance of this physiological function of AHR by extremely persistent high-affinity xenobiotic ligands such as dioxin may represent the most important contributing factor for their potent toxicity.
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18
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Neve EPA, Ingelman-Sundberg M. Intracellular transport and localization of microsomal cytochrome P450. Anal Bioanal Chem 2008; 392:1075-84. [DOI: 10.1007/s00216-008-2200-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2008] [Revised: 05/19/2008] [Accepted: 05/21/2008] [Indexed: 11/27/2022]
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Boysen G, Georgieva NI, Upton PB, Walker VE, Swenberg JA. N-terminal globin adducts as biomarkers for formation of butadiene derived epoxides. Chem Biol Interact 2007; 166:84-92. [PMID: 17084829 DOI: 10.1016/j.cbi.2006.10.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Revised: 09/18/2006] [Accepted: 10/06/2006] [Indexed: 11/25/2022]
Abstract
The aim of this review is to summarize our recent data on butadiene (BD) derived hemoglobin adducts as biomarkers for the internal formation of the individual epoxides formed by butadiene (BD). It is well known that BD is oxidized by cytochrome P450s to several epoxides that form DNA and protein adducts. 1,2-Epoxy-3-butene (EB), 1,2;3,4-diepoxybutane (DEB) and 1,2-epoxy-3,4-butanediol (EB-diol) form N-(2-hydroxy-3-butenyl)-valine (HB-Val), N,N-(2,3-dihydroxy-1,4-butadiyl)-valine (pyr-Val) and N-(2,3,4-trihydroxybutyl)-valine (THB-Val) adducts, respectively. The analysis of HB-Val and THB-Val by the modified Edman degradation and GC-MS/MS has generated valuable insights into BD metabolism across species. In addition, a recently established method for the analysis of pyr-Val has been proven to be suitable for detection of pyr-Val in rodents exposed to BD as low as 1 ppm. These technologies have been applied to study a wide range of exposures to BD, EB, DEB, and 3-butene-1,2-diol as a precursor of EB-diol in male and female mice and rats. Altogether the data have shown that BD metabolism is species and concentration dependent, consistent with metabolism and carcinogenesis data. Mice form much more HB-Val and pyr-Val than rats, especially at low exposures. After 10 days of inhalation exposure to 3 ppm BD, mice formed 12.5-fold more pyr-Val than rats. In contrast, the amounts of THB-Val were similar in mice and rats exposed to 3 or 62.5 ppm BD. Furthermore, it appears that the formation of THB-Val is supralinear in mice and rats due to saturation of metabolic activation pathways. Gender differences in metabolism are less well established. One study with male and female rats exposed to 1000 ppm BD for 90 days demonstrated a 1.6-, 3.5- and 2.0-fold gender difference in formation of HB-Val, pyr-Val and THB-Val, respectively, with females being more efficient in epoxide formation. The analyses of BD derived protein adducts correlate well with the observed species and gender differences in BD-carcinogenesis and suggest that DEB may indeed be the most important metabolite.
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Affiliation(s)
- Gunnar Boysen
- Department of Environmental Sciences and Engineering, The University of North Carolina, Chapel Hill, NC 27599-7431, USA.
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20
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Sunder‐Plassmann R. Cytochrome P450: Another Player in the Myocardial Infarction Game? Adv Clin Chem 2007. [DOI: 10.1016/s0065-2423(06)43008-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Oesch-Bartlomowicz B, Oesch F. Phosphorylation of cytochromes P450: First discovery of a posttranslational modification of a drug-metabolizing enzyme. Biochem Biophys Res Commun 2005; 338:446-9. [PMID: 16137648 DOI: 10.1016/j.bbrc.2005.08.092] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Indexed: 10/25/2022]
Abstract
Cytochromes P450 (CYP) are important components of xenobiotic-metabolizing monooxygenases (CYP-dependent monooxygenases). Their regulation by induction, most commonly by transcriptional activation, mediated by xenobiotics, normally substrates of the corresponding CYP, is well known and has been widely studied. Our team has discovered an additional important regulation of xenobiotic-metabolizing CYPs pertaining to posttranslational modification by phosphorylation. Individual CYPs are phosphorylated by different protein kinases, leading to CYP isoenzyme-selective changes in the metabolism of individual substrates and consequent drastic changes in the control of genotoxic metabolites. Best studied are the CYP phosphorylations by the cAMP-dependent protein kinase A. Most recently, we discovered that cAMP not only leads to drastic changes in the activity of individual CYPs, but also to drastic changes in the nuclear localization of the CYP-related transcription factor Ah receptor (AHR). The consequences are very different from those of AHR nuclear translocation mediated by the classical ligands (enzyme inducers such as dioxin) and are likely to represent the long-sought physiological function of the AHR, its persistent disturbance by long-lived ligands such as dioxin may well be the reason for its high toxicity.
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Affiliation(s)
- B Oesch-Bartlomowicz
- Institute of Toxicology, University of Mainz, Obere Zahlbacherstr. 67, D-55131 Mainz, Germany.
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22
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Aguiar M, Masse R, Gibbs BF. Regulation of cytochrome P450 by posttranslational modification. Drug Metab Rev 2005; 37:379-404. [PMID: 15931769 DOI: 10.1081/dmr-46136] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cytochrome P450s are a family of enzymes represented in all kingdoms with expression in many species. Over 3,000 enzymes have been identified in nature. Humans express 57 putatively functional enzymes with a variety of critical physiological roles. They are involved in the metabolic oxidation, peroxidation, and reduction of many endogenous and exogenous compounds including xenobiotics, steroids, bile acids, fatty acids, eicosanoids, environmental pollutants, and carcinogens [Nelson, D. R., Kamataki, T., Waxman, D. J., Guengerich, F. P., Estabrook, R. W., Feyereisen, R., Gonzalez, F. J., Coon, M. J., Gunsalus, I. C., Gotoh, O. (1993) The P450 superfamily: update on new sequences, gene mapping, accession numbers, early trivial names of enzymes, and nomenclature. DNA Cell Biol. 12(1):1-51.] The development of numerous diseases and disorders including cancer and cardiovascular and endocrine dysfunction has been linked to P450s. Several levels of regulation, including transcription, translation, and posttranslational modification, participate in maintaining the proper function of P450s. Modifications including phosphorylation, glycosylation, nitration, and ubiquitination have been described for P450s. Their physiological significance includes modulation of enzyme activity, targeting to specific cellular compartments, and tagging for proteasomal degradation. Knowledge of P450 posttranslational regulation is derived from studies with relatively few enzymes. In many cases, there is only enough evidence to suggest the occurrence and a possible role for the modification. Thus, many P450 enzymes have not been fully characterized. With the introduction of current proteomics tools, we are primed to answer many important questions regarding regulation of P450 in response to a posttranslational modification. This review considers regulation of P450 in a context that describes the potential role and physiological significance of each modification.
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Affiliation(s)
- Mike Aguiar
- Applied R&D, MDS Pharma Services, St. Laurent (Montreal), Quebec, Canada
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Basu NK, Kovarova M, Garza A, Kubota S, Saha T, Mitra PS, Banerjee R, Rivera J, Owens IS. Phosphorylation of a UDP-glucuronosyltransferase regulates substrate specificity. Proc Natl Acad Sci U S A 2005; 102:6285-90. [PMID: 15845768 PMCID: PMC1088353 DOI: 10.1073/pnas.0407872102] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
UDP-glucuronosyltransferase (UGT) isozymes catalyze detoxification of numerous chemical toxins present in our daily diet and environment by conjugation to glucuronic acid. The special properties and enzymatic mechanism(s) that enable endoplasmic reticulum-bound UGT isozymes to convert innumerable structurally diverse lipophiles to excretable glucuronides are unknown. Inhibition of cellular UGT1A7 and UGT1A10 activities and of [33P]orthophosphate incorporation into immunoprecipitable proteins after exposure to curcumin or calphostin-C indicated that the isozymes are phosphorylated. Furthermore, inhibition of UGT phosphorylation and activity by treatment with PKCepsilon-specific inhibitor peptide supported PKC involvement. Co-immunoprecipitation, colocalization by means of immunofluorescence, and cross-linking studies of PKCepsilon and UGT1A7His revealed that the proteins reside within 11.4 angstroms of each other. Moreover, mutation of three PKC sites in each UGT isozyme demonstrated that T73A/G and T202A/G caused null activity, whereas S432G-UGT1A7 caused a major shift of its pH-8.5 optimum to 6.4 with new substrate selections, including 17beta-estradiol. S432G-UGT1A10 exhibited a minor pH shift without substrate alterations. PKCepsilon involvement was confirmed by the demonstration that PKCepsilon overexpression enhanced activity of UGT1A7 but not of its S432 mutant and the conversion of 17beta-[14C]estradiol by S432G-UGT1A7 but not by UGT1A7. Consistent with these observations, treatment of UGT1A7-transfected cells with PKCepsilon-specific inhibitor peptide or general PKC inhibitors increased 17beta-estradiol catalysis between 5- and 11-fold, with parallel decreases in phosphoserine-432. Here, we report a mechanism involving PKC-mediated phosphorylation of UGT such that phosphoserine/threonine regulates substrate specificity in response to chemical exposures, which possibly confers survival benefit.
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Affiliation(s)
- Nikhil K Basu
- Heritable Disorders Branch, National Institute of Child Health and Human Development, National Institutes of Health, Building 10, Room 9S-241, Bethesda, MD 20892-1830, USA
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Oesch-Bartlmowicz B, Oesch F. Modulation of mutagenicity by phosphorylation of mutagen-metabolizing enzymes. Arch Biochem Biophys 2004; 423:31-6. [PMID: 14989261 DOI: 10.1016/j.abb.2003.11.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In this Minireview, we discuss our findings on phosphorylation of cytochromes P450 (CYP) and influence of this modification on metabolic toxification and/or detoxification of a variety of mutagens. We show that phosphorylation drastically interferes with the mutagenicity of several classes of compounds which are of high human relevance (cytostatic drugs of the cyclophosphamide type, aromatic amines/amides, and nitrosamines). We illustrate this by describing the consequences of the stimulation of protein kinase A (with the example of CYP2B1 and CYP2E1), stimulation of protein kinase C, and inhibition of protein phosphatases PP1 and PP2A (with the example of CYP1A1 and CYP1A2). We discuss a possible mechanism governing these phosphorylation events.
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Watts M, Pankhurst NW, King HR. Maintenance of Atlantic salmon (Salmo salar) at elevated temperature inhibits cytochrome P450 aromatase activity in isolated ovarian follicles. Gen Comp Endocrinol 2004; 135:381-90. [PMID: 14723890 DOI: 10.1016/j.ygcen.2003.11.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Atlantic salmon (Salmo salar) broodstock were transferred from natural (12-16 degrees C) to controlled temperatures of 14, 18 or 22 degrees C for 3 months during vitellogenesis. Fertility and survival were significantly reduced in eggs from broodstock held at 22 degrees C relative to 14 or 18 degrees C. Endocrine mechanisms were disrupted after only one month at 22 degrees C, as evidenced by decreased plasma vitellogenin (Vtg) and increased plasma testosterone (T) levels and, at later stages, decreased levels of plasma 17beta-estradiol (E2). In vitro incubations of isolated ovarian follicles were carried out at monthly intervals, with follicles exposed to human chorionic gonadotropin, N-2-0-dibutyryladenosine 3,5-cyclic monophosphate, and the gonadal steroid precursors 17-hydroxyprogesterone, androstenedione, and T. After one month of exposure to controlled temperature, T synthesis was generally enhanced in response to all treatments at all temperatures, but E2 synthesis was inhibited at 22 degrees C, suggesting temperature impairment of cytochrome P450 aromatase (P450arom) synthesis or activity. The effect became less marked as follicles matured suggesting that temperature sensitivity is stage dependent. The results of this study suggest that the inhibitory effects of elevated temperature on E2 and Vtg synthesis, and subsequent egg development found in the present and earlier studies, arise at least partly, from temperature modulation of P450arom.
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Affiliation(s)
- Marianne Watts
- School of Aquaculture, Tasmanian Aquaculture and Fisheries Institute, University of Tasmania, Locked Bag 1370, Launceston, Tasmania 7250, Australia.
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Stannard C, Soskic V, Godovac-Zimmermann J. Rapid Changes in the Phosphoproteome Show Diverse Cellular Responses Following Stimulation of Human Lung Fibroblasts with Endothelin-1. Biochemistry 2003; 42:13919-28. [PMID: 14636060 DOI: 10.1021/bi035414u] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rapid phosphorylation and dephosphorylation of a variety of proteins downstream of the endothelin receptors A and B was investigated following stimulation of human lung fibroblasts with endothelin-1. Changes in the phosphorylation of proteins involved in the cell cycle, cytoskeleton, membrane channels, transcription, angiogenesis, and metabolism were observed. From observed changes in protein phosphatase 2A, CDC25 A, and caspase-2 precursor, a model for the promotion of cell cycle progression by ET-1 stimulation is proposed. This may offer insights into the mechanisms by which ET-1 exerts its mitogenic effects. The identities of the other proteins phosphorylated within 2 min of stimulation indicate that endothelin-1 also rapidly engages a diverse variety of other cellular responses.
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Affiliation(s)
- Corinne Stannard
- Centre for Molecular Medicine, Department of Medicine, University College London, United Kingdom
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27
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Abstract
Xenobiotic metabolizing cytochromes P450 (CYP) were shown to be phosphorylated in vitro (using purified protein kinases together with purified CYPs), in intact cells (in V79 cells after transfection of cDNAs coding for individual CYPs, in diagnostic mutants, in hepatocytes), and in whole organisms (rats). CYP phosphorylation is highly isoenzyme selective in that only some CYPs are phosphorylated. Protein kinase A (PKA) was identified as a major catalyst for the phosphorylation of CYPs. The PKA recognition motif Arg-Arg-X-Ser is present in several members of the CYP2 family, but is used by only some of them, most notably by CYP2B1/2B2 and CYP2E1. For CYP2B1 it was shown that a substantial portion but not the entire pool of CYP2B1 molecules is phosphorylated and that the phosphorylated portion is catalytically fully inactive. Phosphorylation of CYPs is a very fast process (visible at the earliest time point experimentally investigated after introduction of phosphorylation-supporting measures, which was 2.5min) and the phosphorylated protein is immediately inactive (i.e., the time curves of phosphorylation and inactivation are superimposable). Thus in contrast to the slower process controlling CYP activities by enzyme induction, CYP phosphorylation controls CYP function like a switch. The physical entity of the switch was identified by site-directed mutation as the phosphoryl acceptor Ser in the PKA recognition motif, which is Ser(138) in CYPs 2B (rat CYP2B1 and rabbit CYP2B4) and its homologous Ser(139) in CYP2E1. The function of this switch was demonstrated for the drastic changes in the control of the genotoxic metabolites of mutagenic carcinogens as well as for the control of effectiveness versus unwanted toxicity of cytostatic cancer drugs.
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Robin MA, Anandatheerthavarada HK, Biswas G, Sepuri NBV, Gordon DM, Pain D, Avadhani NG. Bimodal targeting of microsomal CYP2E1 to mitochondria through activation of an N-terminal chimeric signal by cAMP-mediated phosphorylation. J Biol Chem 2002; 277:40583-93. [PMID: 12191992 PMCID: PMC3800117 DOI: 10.1074/jbc.m203292200] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome P450 2E1 (CYP2E1) plays an important role in alcohol-induced toxicity and oxidative stress. Recently, we showed that this predominantly microsomal protein is also localized in rat hepatic mitochondria. In this report, we show that the N-terminal 30 amino acids of CYP2E1 contain a chimeric signal for bimodal targeting of the apoprotein to endoplasmic reticulum (ER) and mitochondria. We demonstrate that the cryptic mitochondrial targeting signal at sequence 21-31 of the protein is activated by cAMP-dependent phosphorylation at Ser-129. S129A mutation resulted in lower affinity for binding to cytoplasmic Hsp70, mitochondrial translocases (TOM40 and TIM44) and reduced mitochondrial import. S129A mutation, however, did not affect the extent of binding to the signal recognition particle and association with ER membrane translocator protein Sec61. Addition of saturating levels of signal recognition particle caused only a partial inhibition of CYP2E1 translation under in vitro conditions, and saturating levels of ER resulted only in partial membrane integration. cAMP enhanced the mitochondrial CYP2E1 (referred to as P450MT5) level but did not affect its level in the ER. Our results provide new insights on the mechanism of cAMP-mediated activation of a cryptic mitochondrial targeting signal and regulation of P450MT5 targeting to mitochondria.
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Affiliation(s)
- Marie-Anne Robin
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Hindupur K. Anandatheerthavarada
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Gopa Biswas
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Naresh Babu V. Sepuri
- Department of Biochemistry and Pharmacology, Thomas Jefferson University Medical School, Philadelphia, Pennsylvania 19107
| | - Donna M. Gordon
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Debkumar Pain
- Department of Pharmacology and Physiology, University of Medicine and Dentistry of New Jersey, Newark, New Jersey 07103
| | - Narayan G. Avadhani
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Oesch-Bartlomowicz B, Oesch F. Fast regulation of cytochrome P450 activities by phosphorylation and consequences for drug metabolism and toxicity. Biol Chem 2002; 383:1587-92. [PMID: 12452435 DOI: 10.1515/bc.2002.179] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In contrast to the well-known regulation of cytochrome P450 (CYP) activity by enzyme induction, which represents a process with slow onset and slow offset, more recent studies revealed phosphorylation as a fast (within observation instantaneous) and isoenzyme-selective regulation. The phosphorylated enzyme (investigated isozyme: CYP2B1) was fully inactive. The phosphorylation is mediated by PKA and hence under control of hormones and drugs that alter cellular cAMP levels. The consequences for the metabolic control of toxic species derived from drugs and environmental carcinogens are discussed. This information will help to improve therapy with drugs metabolized by CYPs which are phosphorylated by PKA, especially if these drugs possess a narrow window between required effectiveness and unacceptable toxicity.
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30
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Oesch-Bartlomowicz B, Richter B, Becker R, Vogel S, Padma PR, Hengstler JG, Oesch F. cAMP-dependent phosphorylation of CYP2B1 as a functional switch for cyclophosphamide activation and its hormonal control in vitro and in vivo. Int J Cancer 2001; 94:733-42. [PMID: 11745470 DOI: 10.1002/ijc.1517] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An important feature of cytochrome P450 (CYP) 2B1 is its high ability to convert the prodrug cyclophosphamide (CPA) to therapeutically cytotoxic metabolites, resulting in interstrand DNA-cross-linking and cell death. We have examined whether and how the phosphorylation of CYP2B1 influences CPA metabolic activation in vitro and in vivo. We found first that only part of the total CYP2B1 pool undergoes phosphorylation. This part is fully inactivated. Second, phosphorylation of CYP2B1 in intact hepatocytes reduced by up to 75% toxification of CPA to mutagenic metabolites (totally dependent on the same preferentially CYP2B-catalyzed 4-hydroxylation of CPA as is the generation of highly cytotoxic species). Third, the phosphoacceptor-serine 128 of CYP2B1 in the consensus sequence for interaction with the protein kinase A represents an on/off switch for the activation of CPA depending on the phosphorylation conditions in the cell. Fourth, evidence is presented that the above-described events also occur in vivo. In conclusion, a successful therapy with CPA, helped by forced expression of CYP2B1 in tumor cells (as recently proposed) will, in addition, be profoundly modified by its phosphorylation status.
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31
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Shozu M, Sumitani H, Murakami K, Segawa T, Yang HJ, Inoue M. Regulation of aromatase activity in bone-derived cells: possible role of mitogen-activated protein kinase. J Steroid Biochem Mol Biol 2001; 79:61-5. [PMID: 11850208 DOI: 10.1016/s0960-0760(01)00129-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Fetal human osteoblast-like cells and the THP-1 cell line that differentiates into macrophage/osteoblast-like cells in the presence of Vitamin D3 and which possesses high aromatase activity, constitute a useful model with which to study the regulation of aromatase in bone. We showed that dexamethasone (DEX)-induced aromatase activity in the THP-1 cell line is completely suppressed by forskolin and by dibutyryl cAMP. We therefore investigated the contribution of mitogen-activated protein kinase (MAPK) to the regulation of aromatase, because cAMP inhibits MAPK in many cells. We examined the role of MAPK on aromatase activity using PD98059, a selective inhibitor of MEK-1. PD98059 (100 microM) reduced DEX+interleukin (IL)-1beta-induced aromatase activity in human osteoblast-like cells by more than 90%, whereas 50% of the aromatase mRNA concentration was retained compared with the control incubated with DEX+IL-1beta. PD98059 (50 microM) reduced the activity of aromatase in THP-1 cells by 80% without significantly affecting the mRNA level. These results indicated that MAPK plays an important role in aromatase activation at the post-transcriptional level.
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Affiliation(s)
- M Shozu
- Department of Obstetrics and Gynecology, School of Medicine, Kanazawa University, 13-1 Takara-machi, 920-0934, Kanazawa, Japan.
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32
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Affiliation(s)
- J B Shabb
- Department of Biochemistry and Molecular Biology, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota 58202-9037, USA.
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33
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Liu DY, Gorrod JW. Effects of cAMP-dependent protein kinase and ATP on N1-oxidation of 9-benzyladenine by animal hepatic microsomes. Life Sci 2000; 66:77-88. [PMID: 10658926 DOI: 10.1016/s0024-3205(99)00563-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
N1-Oxidation is a major metabolic pathway for 9-benzyladenine (BA) catalyzed by the cytochrome P450 system in animal hepatic microsomes. After normal hamster hepatic microsomes or phenobarbital induced rabbit hepatic microsomes were preincubated in the presence of cyclic AMP-dependent protein kinase catalytic subunit (PKA), MgCl2 and ATP, BA-N1-oxidation was significantly decreased. However, further investigation indicated that the decrease of BA-N1-oxidation seemed to be a combination of the effects of PKA and ATP, as ATP alone showed a biphasic regulatory effect on BA-N1-oxidation when microsomes were preincubated in the presence of various concentrations of ATP. In the lower ATP concentration range (0.5-2.5mM), BA-N1-oxidation increased along with the increase of ATP concentration; whereas BA-N1-oxidation decreased when the ATP concentration was higher (>5mM). The biphasic regulatory effects of ATP on BA-N1-oxidation seem dependent on the incubation process, as preincubation markedly strengthened the effects. When microsomes were incubated at 37 degrees C for different time lengths in the absence or presence of ATP (2.5 or 20mM), the activity of BA-N1-oxidase decreased at similar rates in all groups, but the activity levels of BA-N1-oxidase were different among the groups. The cytochrome P450 content was not changed parallel to the variation of BA-N1-oxidation when microsomes were incubated in the presence of ATP, indicating that the effects of ATP on BA-N1-oxidation were not mediated by affecting CYP stability. In addition, the activity of NADPH-cytochrome P450 reductase was not markedly affected by ATP without incubation. The result implied that ATP did not inhibit the reductase directly. After microsomes were incubated in the presence of low ATP concentration (2.5mM), the reductase was slightly inhibited, whilst high ATP concentration (20mM) showed marked inhibition (83% of control). This may partially contribute to the down-regulatory effect of ATP on BA-N1-oxidation. Furthermore, it was found that the presence of magnesium ions during preincubation weakened the up-regulatory effect of ATP (2.5mM) on BA-N1-oxidation, but showed no effect on the down-regulatory effect of ATP (20mM). Since these observed phenomena are not readily explained, a possible mechanism, i.e. phosphorylation and dephosphorylation of cytochrome P450, is suggested.
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Affiliation(s)
- D Y Liu
- Department of Pharmacy, King's College London, University of London, UK
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