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Montoya-Durango D, Walter MN, Rodriguez W, Wang Y, Chariker JH, Rouchka EC, Maldonado C, Barve S, McClain CJ, Gobejishvili L. Dysregulated Cyclic Nucleotide Metabolism in Alcohol-Associated Steatohepatitis: Implications for Novel Targeted Therapies. BIOLOGY 2023; 12:1321. [PMID: 37887031 PMCID: PMC10604143 DOI: 10.3390/biology12101321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 09/29/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023]
Abstract
BACKGROUND Cyclic nucleotides are second messengers, which play significant roles in numerous biological processes. Previous work has shown that cAMP and cGMP signaling regulates various pathways in liver cells, including Kupffer cells, hepatocytes, hepatic stellate cells, and cellular components of hepatic sinusoids. Importantly, it has been shown that cAMP levels and enzymes involved in cAMP homeostasis are affected by alcohol. Although the role of cyclic nucleotide signaling is strongly implicated in several pathological pathways in liver diseases, studies describing the changes in genes regulating cyclic nucleotide metabolism in ALD are lacking. METHODS Male C57B/6 mice were used in an intragastric model of alcohol-associated steatohepatitis (ASH). Liver injury, inflammation, and fibrogenesis were evaluated by measuring plasma levels of injury markers, liver tissue cytokines, and gene expression analyses. Liver transcriptome analysis was performed to examine the effects of alcohol on regulators of cyclic AMP and GMP levels and signaling. cAMP and cGMP levels were measured in mouse livers as well as in livers from healthy human donors and patients with alcohol-associated hepatitis (AH). RESULTS Our results show significant changes in several phosphodiesterases (PDEs) with specificity to degrade cAMP (Pde4a, Pde4d, and Pde8a) and cGMP (Pde5a, Pde6d, and Pde9a), as well as dual-specificity PDEs (Pde1a and Pde10a) in ASH mouse livers. Adenylyl cyclases (ACs) 7 and 9, which are responsible for cAMP generation, were also affected by alcohol. Importantly, adenosine receptor 1, which has been implicated in the pathogenesis of liver diseases, was significantly increased by alcohol. Adrenoceptors 1 and 3 (Adrb), which couple with stimulatory G protein to regulate cAMP and cGMP signaling, were significantly decreased. Additionally, beta arrestin 2, which interacts with cAMP-specific PDE4D to desensitize G-protein-coupled receptor to generate cAMP, was significantly increased by alcohol. Notably, we observed that cAMP levels are much higher than cGMP levels in the livers of humans and mice; however, alcohol affected them differently. Specifically, cGMP levels were higher in patients with AH and ASH mice livers compared with controls. As expected, these changes in liver cyclic nucleotide signaling were associated with increased inflammation, steatosis, apoptosis, and fibrogenesis. CONCLUSIONS These data strongly implicate dysregulated cAMP and cGMP signaling in the pathogenesis of ASH. Future studies to identify changes in these regulators in a cell-specific manner could lead to the development of novel targeted therapies for ASH.
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Affiliation(s)
- Diego Montoya-Durango
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
| | - Mary Nancy Walter
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
| | - Walter Rodriguez
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
| | - Yali Wang
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
| | - Julia H. Chariker
- Department of Neuroscience Training, University of Louisville, Louisville, KY 40290, USA;
- KY INBRE Bioinformatics Core, University of Louisville, Louisville, KY 40290, USA;
| | - Eric C. Rouchka
- KY INBRE Bioinformatics Core, University of Louisville, Louisville, KY 40290, USA;
- Department of Biochemistry and Molecular Genetics, University of Louisville, Louisville, KY 40292, USA
| | - Claudio Maldonado
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
| | - Shirish Barve
- Department of Medicine, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (S.B.); (C.J.M.)
- Alcohol Research Center, University of Louisville, Louisville, KY 40290, USA
| | - Craig J. McClain
- Department of Medicine, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (S.B.); (C.J.M.)
- Alcohol Research Center, University of Louisville, Louisville, KY 40290, USA
- Robley Rex VA Medical Center, Louisville, KY 40206, USA
- Department of Pharmacology & Toxicology, School of Medicine, University of Louisville, Louisville, KY 40290, USA
| | - Leila Gobejishvili
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (D.M.-D.); (M.N.W.); (W.R.); (Y.W.); (C.M.)
- Department of Medicine, School of Medicine, University of Louisville, Louisville, KY 40290, USA; (S.B.); (C.J.M.)
- Alcohol Research Center, University of Louisville, Louisville, KY 40290, USA
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Abburi C, McDaid J. Ethanol interaction with α3β4 nicotinic acetylcholine receptors in neurons of the laterodorsal tegmentum. Alcohol Clin Exp Res 2021; 45:2495-2505. [PMID: 34625982 DOI: 10.1111/acer.14727] [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: 03/30/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChRs) play a key role in the rewarding effects of ethanol (EtOH), and while several nAChR subtypes have been implicated, attention has recently shifted to a role for the α3β4 nAChR. The laterodorsal tegmental nucleus (LDTg), a brainstem cholinergic nucleus that sends excitatory projections to the ventral tegmental area, is an Integral part of the brain reward pathway. Here we investigate a potential role for LDTg α3β4 nAChRs in EtOH self-administration and reward. METHODS Sprague-Dawley rats were given ad libitum access to a 20% EtOH solution, as part of a two-bottle choice paradigm. Approximately 1 week after removal of EtOH access, we measured LDTg α3β4 nAChR current responses to focal application of acetylcholine (ACh), using whole-cell patch clamp electrophysiology recordings in acute brain slices. In addition, we used whole-cell electrophysiology to assess the acute effects of EtOH on the sensitivity of LDTg α3β4 nAChRs. RESULTS Focal application of ACh onto LDTg neurons resulted in large α3β4 nAChR-mediated inward currents, the magnitude of which showed a positive correlation with levels of EtOH self-administration. In addition, using brain slices taken from EtOH-naïve rats, bath application of EtOH resulted in a moderate potentiation of LDTg α3β4 nAChR sensitivity. CONCLUSIONS Using a rat model, increased α3β4 nAChR function was associated with greater EtOH self-administration, with α3β4 nAChR function also acutely potentiated by EtOH. Assuming that similar findings apply to humans, the α3β4 nAChR could be a therapeutic target in the treatment of EtOH use disorder.
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Affiliation(s)
- Chandrika Abburi
- Department of Anesthesia and Critical Care, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois, 60637, USA
| | - John McDaid
- Department of Anesthesia and Critical Care, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois, 60637, USA
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cAMP Signaling in Pathobiology of Alcohol Associated Liver Disease. Biomolecules 2020; 10:biom10101433. [PMID: 33050657 PMCID: PMC7600246 DOI: 10.3390/biom10101433] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 10/07/2020] [Accepted: 10/08/2020] [Indexed: 02/07/2023] Open
Abstract
The importance of cyclic adenosine monophosphate (cAMP) in cellular responses to extracellular signals is well established. Many years after discovery, our understanding of the intricacy of cAMP signaling has improved dramatically. Multiple layers of regulation exist to ensure the specificity of cellular cAMP signaling. Hence, disturbances in cAMP homeostasis could arise at multiple levels, from changes in G protein coupled receptors and production of cAMP to the rate of degradation by phosphodiesterases. cAMP signaling plays critical roles in metabolism, inflammation and development of fibrosis in several tissues. Alcohol-associated liver disease (ALD) is a multifactorial condition ranging from a simple steatosis to steatohepatitis and fibrosis and ultimately cirrhosis, which might lead to hepatocellular cancer. To date, there is no FDA-approved therapy for ALD. Hence, identifying the targets for the treatment of ALD is an important undertaking. Several human studies have reported the changes in cAMP homeostasis in relation to alcohol use disorders. cAMP signaling has also been extensively studied in in vitro and in vivo models of ALD. This review focuses on the role of cAMP in the pathobiology of ALD with emphasis on the therapeutic potential of targeting cAMP signaling for the treatment of various stages of ALD.
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Lu Y, Cederbaum AI. Cytochrome P450s and Alcoholic Liver Disease. Curr Pharm Des 2018; 24:1502-1517. [PMID: 29637855 PMCID: PMC6053342 DOI: 10.2174/1381612824666180410091511] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/30/2018] [Accepted: 04/06/2018] [Indexed: 12/19/2022]
Abstract
Alcohol consumption causes liver diseases, designated as Alcoholic Liver Disease (ALD). Because alcohol is detoxified by alcohol dehydrogenase (ADH), a major ethanol metabolism system, the development of ALD was initially believed to be due to malnutrition caused by alcohol metabolism in liver. The discovery of the microsomal ethanol oxidizing system (MEOS) changed this dogma. Cytochrome P450 enzymes (CYP) constitute the major components of MEOS. Cytochrome P450 2E1 (CYP2E1) in MEOS is one of the major ROS generators in liver and is considered to be contributive to ALD. Our labs have been studying the relationship between CYP2E1 and ALD for many years. Recently, we found that human CYP2A6 and its mouse analog CYP2A5 are also induced by alcohol. In mice, the alcohol induction of CYP2A5 is CYP2E1-dependent. Unlike CYP2E1, CYP2A5 protects against the development of ALD. The relationship of CYP2E1, CYP2A5, and ALD is a major focus of this review.
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Affiliation(s)
- Yongke Lu
- Department of Health Sciences, College of Public Health, East Tennessee State University
- Center of Excellence for Inflammation, Infectious Disease and Immunity, East Tennessee State University
| | - Arthur I. Cederbaum
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai
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Avila DV, Barker DF, Zhang J, McClain CJ, Barve S, Gobejishvili L. Dysregulation of hepatic cAMP levels via altered Pde4b expression plays a critical role in alcohol-induced steatosis. J Pathol 2017; 240:96-107. [PMID: 27287961 DOI: 10.1002/path.4760] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/06/2016] [Accepted: 05/31/2016] [Indexed: 12/15/2022]
Abstract
Alcohol-induced hepatic steatosis is a significant risk factor for progressive liver disease. Cyclic adenosine monophosphate (cAMP) signalling has been shown to significantly regulate lipid metabolism; however, the role of altered cAMP homeostasis in alcohol-mediated hepatic steatosis has never been studied. Our previous work demonstrated that increased expression of hepatic phosphodiesterase 4 (Pde4), which specifically hydrolyses and decreases cAMP levels, plays a pathogenic role in the development of liver inflammation/injury. The aim of this study was to examine the role of PDE4 in alcohol-induced hepatic steatosis. C57BL/6 wild-type and Pde4b knockout (Pde4b(-/-) ) mice were pair-fed control or ethanol liquid diets. One group of wild-type mice received rolipram, a PDE4-specific inhibitor, during alcohol feeding. We demonstrate for the first time that an early increase in PDE4 enzyme expression and a resultant decrease in hepatic cAMP levels are associated with the significant reduction in carnitine palmitoyltransferase 1A (Cpt1a) expression. Notably, alcohol-fed (AF) Pde4b(-/-) mice and AF wild-type mice treated with rolipram had significantly lower hepatic free fatty acid content compared with AF wild-type mice. Importantly, PDE4 inhibition in alcohol-fed mice prevented the decrease in hepatic Cpt1a expression via the Pparα/Sirt1/Pgc1α pathway. These results demonstrate that the alcohol- induced increase in hepatic Pde4, specifically Pde4b expression, and compromised cAMP signalling predispose the liver to impaired fatty acid oxidation and the development of steatosis. Moreover, these data also suggest that hepatic PDE4 may be a clinically relevant therapeutic target for the treatment of alcohol-induced hepatic steatosis. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Diana V Avila
- Department of Pharmacology and Toxicology, University of Louisville Medical Center, Louisville, Kentucky, USA
| | - David F Barker
- Department of Internal Medicine, University of Louisville Medical Center, Louisville, Kentucky, USA
| | - JingWen Zhang
- Department of Internal Medicine, University of Louisville Medical Center, Louisville, Kentucky, USA
| | - Craig J McClain
- Department of Pharmacology and Toxicology, University of Louisville Medical Center, Louisville, Kentucky, USA.,Department of Internal Medicine, University of Louisville Medical Center, Louisville, Kentucky, USA.,Robley Rex VA Medical Center, Louisville, Kentucky, USA
| | - Shirish Barve
- Department of Pharmacology and Toxicology, University of Louisville Medical Center, Louisville, Kentucky, USA.,Department of Internal Medicine, University of Louisville Medical Center, Louisville, Kentucky, USA
| | - Leila Gobejishvili
- Department of Pharmacology and Toxicology, University of Louisville Medical Center, Louisville, Kentucky, USA.,Department of Internal Medicine, University of Louisville Medical Center, Louisville, Kentucky, USA
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Bartlett PJ, Antony AN, Agarwal A, Hilly M, Prince VL, Combettes L, Hoek JB, Gaspers LD. Chronic alcohol feeding potentiates hormone-induced calcium signalling in hepatocytes. J Physiol 2017; 595:3143-3164. [PMID: 28220501 DOI: 10.1113/jp273891] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 01/26/2017] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Chronic alcohol consumption causes a spectrum of liver diseases, but the pathogenic mechanisms driving the onset and progression of disease are not clearly defined. We show that chronic alcohol feeding sensitizes rat hepatocytes to Ca2+ -mobilizing hormones resulting in a leftward shift in the concentration-response relationship and the transition from oscillatory to more sustained and prolonged Ca2+ increases. Our data demonstrate that alcohol-dependent adaptation in the Ca2+ signalling pathway occurs at the level of hormone-induced inositol 1,4,5 trisphosphate (IP3 ) production and does not involve changes in the sensitivity of the IP3 receptor or size of internal Ca2+ stores. We suggest that prolonged and aberrant hormone-evoked Ca2+ increases may stimulate the production of mitochondrial reactive oxygen species and contribute to alcohol-induced hepatocyte injury. ABSTRACT: 'Adaptive' responses of the liver to chronic alcohol consumption may underlie the development of cell and tissue injury. Alcohol administration can perturb multiple signalling pathways including phosphoinositide-dependent cytosolic calcium ([Ca2+ ]i ) increases, which can adversely affect mitochondrial Ca2+ levels, reactive oxygen species production and energy metabolism. Our data indicate that chronic alcohol feeding induces a leftward shift in the dose-response for Ca2+ -mobilizing hormones resulting in more sustained and prolonged [Ca2+ ]i increases in both cultured hepatocytes and hepatocytes within the intact perfused liver. Ca2+ increases were initiated at lower hormone concentrations, and intercellular calcium wave propagation rates were faster in alcoholics compared to controls. Acute alcohol treatment (25 mm) completely inhibited hormone-induced calcium increases in control livers, but not after chronic alcohol-feeding, suggesting desensitization to the inhibitory actions of ethanol. Hormone-induced inositol 1,4,5 trisphosphate (IP3 ) accumulation and phospholipase C (PLC) activity were significantly potentiated in hepatocytes from alcohol-fed rats compared to controls. Removal of extracellular calcium, or chelation of intracellular calcium did not normalize the differences in hormone-stimulated PLC activity, indicating calcium-dependent PLCs are not upregulated by alcohol. We propose that the liver 'adapts' to chronic alcohol exposure by increasing hormone-dependent IP3 formation, leading to aberrant calcium increases, which may contribute to hepatocyte injury.
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Affiliation(s)
- Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Anil Noronha Antony
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Amit Agarwal
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Mauricette Hilly
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Victoria L Prince
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Laurent Combettes
- INSERM UMR-S 757, Université de Paris-Sud, bât 443, 91405, Orsay, France
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Lawrence D Gaspers
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
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Leung TM, Lu Y. Alcoholic Liver Disease: from CYP2E1 to CYP2A5. Curr Mol Pharmacol 2017; 10:172-178. [PMID: 26278389 PMCID: PMC5856453 DOI: 10.2174/1874467208666150817111846] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/07/2015] [Accepted: 08/07/2015] [Indexed: 02/08/2023]
Abstract
This article reviews recent studies on CYP2E1-mediated alcoholic liver injury, the induction of CYP2A5 by alcohol and the mechanism for this upregulation, especially the permissive role of CYP2E1 in the induction of CYP2A5 by alcohol and the CYP2E1-ROS-Nrf2 pathway, and protective effects of CYP2A5 against ethanol-induced oxidative liver injury. Ethanol can induce CYP2E1, an active generator of reactive oxygen species (ROS), and CYP2E1 is a contributing factor for alcoholinduced oxidative liver injury. CYP2A5, another isoform of cytochrome P450, can also be induced by ethanol. Chronic feeding of ethanol to wild type mice increased CYP2A5 catalytic activity, protein and mRNA levels as compared to pair-fed controls. This induction was blunted in CYP2E1 knockout (cyp2e1-/-) mice but was restored when human CYP2E1 was reintroduced and expressed in cyp2e1-/- mice. Ethanol-induced CYP2E1 co-localized with CYP2A5 and preceded the elevation of CYP2A5. The antioxidants N-acetyl cysteine and vitamin C lowered the alcohol elevation of ROS and blunted the alcohol induction of CYP2A5, but not CYP2E1, suggesting ROS play a novel role in the crosstalk between CYP2E1 and CYP2A5. The antioxidants blocked the activation of Nrf2, a transcription factor known to upregulate expression of CYP2A5. When alcohol-induced liver injury was enhanced in Nrf2 knockout (Nrf2-/-) mice, alcohol elevation of CYP2A5 but not CYP2E1 was also lower in Nrf2-/- mice. CYP2A5 knockout (cyp2a5-/-) mice exhibited an enhanced alcoholic liver injury compared with WT mice as indicated by serum ALT, steatosis and necroinflammation. Alcohol-induced hyperglycemia were observed in cyp2a5-/- mice but not in WT mice.
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Affiliation(s)
- Tung Ming Leung
- Graduate Program in Public Health, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount. United States
| | - Yongke Lu
- Department of Structural and Chemical Biology, Box 1677, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029. United States
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McDaid J, Abburi C, Wolfman SL, Gallagher K, McGehee DS. Ethanol-Induced Motor Impairment Mediated by Inhibition of α7 Nicotinic Receptors. J Neurosci 2016; 36:7768-78. [PMID: 27445152 PMCID: PMC4951579 DOI: 10.1523/jneurosci.0154-16.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 01/30/2023] Open
Abstract
UNLABELLED Nicotine and ethanol (EtOH) are among the most widely co-abused substances, and nicotinic acetylcholine receptors (nAChRs) contribute to the behavioral effects of both drugs. Along with their role in addiction, nAChRs also contribute to motor control circuitry. The α7 nAChR subtype is highly expressed in the laterodorsal tegmental nucleus (LDTg), a brainstem cholinergic center that contributes to motor performance through its projections to thalamic motor relay centers, including the mediodorsal thalamus. We demonstrate that EtOH concentrations just above the legal limits for intoxication in humans can inhibit α7 nAChRs in LDTg neurons from rats. This EtOH-induced inhibition is mediated by a decrease in cAMP/PKA signaling. The α7 nAChR-positive allosteric modulator PNU120596 [N-(5-chloro-2,4-dimethoxyphenyl)-N'-(5-methyl-3-isoxazolyl)-urea], which interferes with receptor desensitization, completely eliminated EtOH modulation of these receptors. These data suggest that EtOH inhibits α7 responses through a PKA-dependent enhancement of receptor desensitization. EtOH also inhibited the effects of nicotine at presynaptic α7 nAChRs on glutamate terminals in the mediodorsal thalamus. In vivo administration of PNU120596 either into the cerebral ventricles or directly into the mediodorsal thalamus attenuated EtOH-induced motor impairment. Thus, α7 nAChRs are likely important mediators of the motor impairing effects of moderate EtOH consumption. SIGNIFICANCE STATEMENT The motor-impairing effects of ethanol contribute to intoxication-related injury and death. Here we explore the cellular and neural circuit mechanisms underlying ethanol-induced motor impairment. Physiologically relevant concentrations of ethanol inhibit activity of a nicotinic receptor subtype that is expressed in brain areas associated with motor control. That receptor inhibition is mediated by decreased receptor phosphorylation, suggesting an indirect modulation of cell signaling pathways to achieve the physiological effects.
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Affiliation(s)
- John McDaid
- Department of Anesthesia and Critical Care and
| | | | - Shannon L Wolfman
- Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637
| | | | - Daniel S McGehee
- Department of Anesthesia and Critical Care and Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637
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Pérez-Solis MA, Maya-Nuñez G, Casas-González P, Olivares A, Aguilar-Rojas A. Effects of the lifestyle habits in breast cancer transcriptional regulation. Cancer Cell Int 2016; 16:7. [PMID: 26877711 PMCID: PMC4752785 DOI: 10.1186/s12935-016-0284-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 02/03/2016] [Indexed: 12/31/2022] Open
Abstract
Through research carried out in the last 25 years about the breast cancer etiology, it has been possible to estimate that less than 10 % of patients who are diagnosed with the condition are carriers of some germline or somatic mutation. The clinical reports of breast cancer patients with healthy twins and the development of disease in women without high penetrance mutations detected, warn the participation more factors in the transformation process. The high incidence of mammary adenocarcinoma in the modern woman and the urgent need for new methods of prevention and early detection have demanded more information about the role that environment and lifestyle have on the transformation of mammary gland epithelial cells. Obesity, alcoholism and smoking are factors that have shown a close correlation with the risk of developing breast cancer. And although these conditions affect different cell regulation levels, the study of its effects in the mechanisms of transcriptional and epigenetic regulation is considered critical for a better understanding of the loss of identity of epithelial cells during carcinogenesis of this tissue. The main objective of this review was to establish the importance of changes occurring to transcriptional level in the mammary gland as a consequence of acute or chronic exposure to harmful products such as obesity-causing foods, ethanol and cigarette smoke components. At analyze the main studies related to topic, it has concluded that the understanding of effects caused by the lifestyle factors in performance of the transcriptional mechanisms that determine gene expression of the mammary gland epithelial cells, may help explain the development of this disease in women without genetic propensity and different phenotypic manifestations of this cancer type.
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Affiliation(s)
- Marco Allán Pérez-Solis
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Guadalupe Maya-Nuñez
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Patricia Casas-González
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Aleida Olivares
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
| | - Arturo Aguilar-Rojas
- Research Unit in Reproductive Medicine, Hospital de Ginecobstetricia “Luis Castelazo Ayala”, Instituto Mexicano del Seguro Social, No. 289 Río Magdalena, Tizapan San Angel, 01090 Mexico, DF Mexico
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Mons N, Beracochea D. Behavioral Neuroadaptation to Alcohol: From Glucocorticoids to Histone Acetylation. Front Psychiatry 2016; 7:165. [PMID: 27766083 PMCID: PMC5052254 DOI: 10.3389/fpsyt.2016.00165] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/21/2016] [Indexed: 01/21/2023] Open
Abstract
A prime mechanism that contributes to the development and maintenance of alcoholism is the dysregulation of the hypothalamic-pituitary-adrenal axis activity and the release of glucocorticoids (cortisol in humans and primates, corticosterone in rodents) from the adrenal glands. In the brain, sustained, local elevation of glucocorticoid concentration even long after cessation of chronic alcohol consumption compromises functional integrity of a circuit, including the prefrontal cortex (PFC), the hippocampus (HPC), and the amygdala (AMG). These structures are implicated in learning and memory processes as well as in orchestrating neuroadaptive responses to stress and anxiety responses. Thus, potentiation of anxiety-related neuroadaptation by alcohol is characterized by an abnormally AMG hyperactivity coupled with a hypofunction of the PFC and the HPC. This review describes research on molecular and epigenetic mechanisms by which alcohol causes distinct region-specific adaptive changes in gene expression patterns and ultimately leads to a variety of cognitive and behavioral impairments on prefrontal- and hippocampal-based tasks. Alcohol-induced neuroadaptations involve the dysregulation of numerous signaling cascades, leading to long-term changes in transcriptional profiles of genes, through the actions of transcription factors such as [cAMP response element-binding protein (CREB)] and chromatin remodeling due to posttranslational modifications of histone proteins. We describe the role of prefrontal-HPC-AMG circuit in mediating the effects of acute and chronic alcohol on learning and memory, and region-specific molecular and epigenetic mechanisms involved in this process. This review first discusses the importance of brain region-specific dysregulation of glucocorticoid concentration in the development of alcohol dependence and describes how persistently increased glucocorticoid levels in PFC may be involved in mediating working memory impairments and neuroadaptive changes during withdrawal from chronic alcohol intake. It then highlights the role of cAMP-PKA-CREB signaling cascade and histone acetylation within the PFC and limbic structures in alcohol-induced anxiety and behavioral impairments, and how an understanding of functional alterations of these pathways might lead to better treatments for neuropsychiatric disorders.
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Affiliation(s)
- Nicole Mons
- CNRS UMR 5287, Institut des Neurosciences cognitives et intégratives d'Aquitaine, Nouvelle Université de Bordeaux , Pessac , France
| | - Daniel Beracochea
- CNRS UMR 5287, Institut des Neurosciences cognitives et intégratives d'Aquitaine, Nouvelle Université de Bordeaux , Pessac , France
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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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12
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Liangpunsakul S, Ross RA, Crabb DW. Activation of carbohydrate response element-binding protein by ethanol. J Investig Med 2013; 61:270-7. [PMID: 23266705 DOI: 10.2310/jim.0b013e31827c2795] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Carbohydrate response element-binding protein (ChREBP) is a transcription factor involved in hepatic lipogenesis. Its function is in part under the control of AMP-activated protein kinase (AMPK) and protein phosphatase 2A (PP2A). Given known effects of ethanol on AMPK and PP2A, it is plausible that ethanol might enhance fatty acid synthesis by increasing the activity of ChREBP. We hypothesized that another potential pathway of ethanol-induced hepatic steatosis is mediated by activation of ChREBP. METHODS The effects of ethanol on ChREBP were assessed in hepatoma cells and in C57BL/6J mice fed with the Lieber-DeCarli diet. RESULTS When the cells were exposed to ethanol (50 mM) for 24 hours, the activity of a liver pyruvate kinase (LPK) promoter-luciferase reporter was increased by ∼4-fold. Ethanol feeding of mice resulted in the translocation of ChREBP from cytosol to the nucleus. Protein phosphatase 2A activity was increased in the liver of ethanol-fed mice by 22%. We found no difference in the levels of hepatic Xu-5-P between ethanol-fed mice and controls. Transfection of a constitutively active AMPK expression plasmid suppressed the basal activity of the LPK luciferase reporter and abolished the effect of ethanol on the reporter activity. However, transfection of rat hepatoma cells with a dominant-negative AMPK expression plasmid induced basal LPK luciferase activity by only ∼20%. The effect of ethanol on ChREBP was attenuated in the presence of okadaic acid, an inhibitor of PP2A. CONCLUSIONS The effects of ethanol on AMPK and PP2A may result in activation of ChREBP, providing another potential mechanism for ethanol-induced hepatic steatosis. However, additional okadaic acid-insensitive effects appear to be important as well.
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Affiliation(s)
- Suthat Liangpunsakul
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.
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Liangpunsakul S, Ross RA, Crabb DW. Activation of carbohydrate response element-binding protein by ethanol. J Investig Med 2013; 61. [PMID: 23266705 PMCID: PMC3554838 DOI: 10.231/jim.0b013e31827c2795] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Carbohydrate response element-binding protein (ChREBP) is a transcription factor involved in hepatic lipogenesis. Its function is in part under the control of AMP-activated protein kinase (AMPK) and protein phosphatase 2A (PP2A). Given known effects of ethanol on AMPK and PP2A, it is plausible that ethanol might enhance fatty acid synthesis by increasing the activity of ChREBP. We hypothesized that another potential pathway of ethanol-induced hepatic steatosis is mediated by activation of ChREBP. METHODS The effects of ethanol on ChREBP were assessed in hepatoma cells and in C57BL/6J mice fed with the Lieber-DeCarli diet. RESULTS When the cells were exposed to ethanol (50 mM) for 24 hours, the activity of a liver pyruvate kinase (LPK) promoter-luciferase reporter was increased by ∼4-fold. Ethanol feeding of mice resulted in the translocation of ChREBP from cytosol to the nucleus. Protein phosphatase 2A activity was increased in the liver of ethanol-fed mice by 22%. We found no difference in the levels of hepatic Xu-5-P between ethanol-fed mice and controls. Transfection of a constitutively active AMPK expression plasmid suppressed the basal activity of the LPK luciferase reporter and abolished the effect of ethanol on the reporter activity. However, transfection of rat hepatoma cells with a dominant-negative AMPK expression plasmid induced basal LPK luciferase activity by only ∼20%. The effect of ethanol on ChREBP was attenuated in the presence of okadaic acid, an inhibitor of PP2A. CONCLUSIONS The effects of ethanol on AMPK and PP2A may result in activation of ChREBP, providing another potential mechanism for ethanol-induced hepatic steatosis. However, additional okadaic acid-insensitive effects appear to be important as well.
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Affiliation(s)
- Suthat Liangpunsakul
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, 46202,Roudebush Veterans Administration Medical Center, Indiana University School of Medicine, Indianapolis, Indiana, 46202
| | - Ruth A. Ross
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, 46202
| | - David W. Crabb
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, 46202
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14
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Fujimoto Sakata S, Fujino M, Matsuda K, Maeda M, Ohira H, Kawasaki K, Tamaki N. Mechanism of liver tyrosine aminotransferase increase in ethanol-treated mice and its effect on serum tyrosine level. J Nutr Sci Vitaminol (Tokyo) 2008; 53:489-95. [PMID: 18202536 DOI: 10.3177/jnsv.53.489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Liver tyrosine aminotransferase (TAT) activity is known to increase with ethanol treatment; however, the mechanism of this increase is unclear. Upon investigation we found that TAT activity and mRNA levels started to increase 2 h after ethanol administration and continued to increase until 6 h after ethanol administration. The increase in ethanol-induced TAT activity could not be explained by calorie loading after fasting, since ethanol loading increased TAT expression, while glucose loading decreased TAT expression. In addition, liver TAT activity was not related to serum tyrosine levels. TAT activity increased when an adenosine A2 agonist, 5'-N-ethylcarboxamide adenosine, was given. Since TAT activity is increased by cAMP, and ethanol increases cAMP production via an adenosine receptor-dependent mechanism, this increase in ethanol-induced TAT activity may occur via an adenosine receptor-dependent mechanism.
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15
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Covarrubias MY, Khan RL, Vadigepalli R, Hoek JB, Schwaber JS. Chronic alcohol exposure alters transcription broadly in a key integrative brain nucleus for homeostasis: the nucleus tractus solitarius. Physiol Genomics 2006; 24:45-58. [PMID: 16189278 DOI: 10.1152/physiolgenomics.00184.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Chronic exposure to alcohol modifies physiological processes in the brain, and the severe symptoms resulting from sudden removal of alcohol from the diet indicate that these modifications are functionally important. We investigated the gene expression patterns in response to chronic alcohol exposure (21–28 wk) in the rat nucleus tractus solitarius (NTS), a brain nucleus with a key integrative role in homeostasis and cardiorespiratory function. Using methods and an experimental design optimized for detecting transcriptional changes less than twofold, we found 575 differentially expressed genes. We tested these genes for significant associations with physiological functions and signaling pathways using Gene Ontology terms and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, respectively. Chronic alcohol exposure resulted in significant NTS gene regulation related to the general processes of synaptic transmission, intracellular signaling, and cation transport as well as specific neuronal functions including plasticity and seizure behavior that could be related to alcohol withdrawal symptoms. The differentially expressed genes were also significantly enriched for enzymes of lipid metabolism, glucose metabolism, oxidative phosphorylation, MAP kinase signaling, and calcium signaling pathways from KEGG. Intriguingly, many of the genes we found to be differentially expressed in the NTS are known to be involved in alcohol-induced oxidative stress and/or cell death. The study provides evidence of very extensive alterations of physiological gene expression in the NTS in the adapted state to chronic alcohol exposure.
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Affiliation(s)
- Maria Yolanda Covarrubias
- Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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16
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Nagy LE. Molecular aspects of alcohol metabolism: transcription factors involved in early ethanol-induced liver injury. Annu Rev Nutr 2004; 24:55-78. [PMID: 15189113 DOI: 10.1146/annurev.nutr.24.012003.132258] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alcohol metabolism takes place primarily in the liver. Initial exposures to ethanol have a major impact on the hepatic redox state and intermediary metabolism as a consequence of ethanol metabolism via alcohol dehydrogenase. However, upon continued exposure to ethanol, the progression of liver injury involves ethanol metabolism via CYP2E1 and consequent oxidant stress, as well as potential direct effects of ethanol on membrane proteins that are independent of ethanol metabolism. Multiple organ systems contribute to liver injury, including the innate immune system and adipose tissue. In response to ethanol exposure, specific signal transduction pathways, including NFkappaB and the mitogen-activated protein kinase family members ERK1/2, JNK, and p38, are activated. These complex responses to ethanol exposure translate into activation of nuclear transcription factors and altered gene expression within the liver, leading to the development of steatosis and inflammation in the early stages of alcohol-induced liver injury.
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Affiliation(s)
- Laura E Nagy
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106-4906, USA.
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17
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Abstract
Activation of zymogens within the pancreatic acinar cell is an early feature of acute pancreatitis. Supraphysiologic concentrations of cholecystokinin (CCK) cause intrapancreatic zymogen activation and pancreatitis. Supraphysiologic concentrations of CCK also cause zymogen activation in isolated pancreatic acini. This activation first occurs in a nonzymogen granule compartment that contains lysosomal markers. A low pH environment may also be needed for activation. To examine the ability of alcohols to sensitize the acinar cell to CCK, the conversion of zymogens to active enzymes in isolated acini was assayed. Alcohols, including 35 mmol/L ethanol, sensitized acini to CCK induced activation. The sensitization increased with chain length and was less in branched compared with unbranched alcohols. The relationship of alcohol's structure to sensitization may be related to the mechanism of sensitization.
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Affiliation(s)
- Fred S Gorelick
- Department of Internal Medicine (Section of Digestive Diseases), VA Connecticut Healthcare, West Haven and Yale University School of Medicine, New Haven, Connecticut, USA.
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18
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Debelak-Kragtorp KA, Armant DR, Smith SM. Ethanol-induced cephalic apoptosis requires phospholipase C-dependent intracellular calcium signaling. Alcohol Clin Exp Res 2003; 27:515-23. [PMID: 12658119 DOI: 10.1097/01.alc.0000056615.34253.a8] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Although the ability of ethanol to elicit neural crest cell apoptosis is well documented, the initial target of ethanol in these cells, and the biochemical pathway leading to their apoptosis, have yet to be determined. Recent work in preimplantation mouse embryos demonstrates that ethanol induces a phospholipase-C (PLC)-dependent calcium transient that mediates ethanol's effects. We tested whether a similar effect on calcium and PLC is involved in ethanol-induced neural crest apoptosis. METHODS Chicken embryos were collected and loaded with Fluo-3-AM to assess the effects of ethanol on intracellular calcium levels. Pharmacological agents were used to determine the sources and mechanism of intracellular calcium increases. In separate experiments, embryos were treated in ovo with pharmacological modulators of calcium signaling prior to ethanol exposure, and resulting levels of cell death were assessed by using the vital dye acridine orange. RESULTS Ethanol exposure caused a localized increase in intracellular calcium levels in embryonic neural folds within 15 sec of ethanol exposure. Ethanol-induced apoptosis was specifically blocked by chelation of intracellular calcium before ethanol exposure. Pretreatment with the PLC inhibitor U73122 blocked ethanol-induced apoptosis as well as the intracellular calcium transient. Depletion of extracellular calcium resulted in a partial block of ethanol-induced apoptosis. CONCLUSIONS Ethanol exposure alters calcium signaling within the neurulation-stage chicken embryo in a PLC-dependent manner. Increases in intracellular calcium and PLC activity are necessary for ethanol's induction of apoptosis within cephalic populations. These effects likely represent an early and crucial event in the pathway leading to ethanol-induced cell death.
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19
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Ethanol-Induced Translocation of Protein Kinase A Occurs in Two Phases: Control by Different Molecular Mechanisms. Alcohol Clin Exp Res 2002. [DOI: 10.1097/00000374-200203000-00016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Dohrman DP, Chen HM, Gordon AS, Diamond I. Ethanol-Induced Translocation of Protein Kinase A Occurs in Two Phases: Control by Different Molecular Mechanisms. Alcohol Clin Exp Res 2002. [DOI: 10.1111/j.1530-0277.2002.tb02553.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Node K, Ruan XL, Dai J, Yang SX, Graham L, Zeldin DC, Liao JK. Activation of Galpha s mediates induction of tissue-type plasminogen activator gene transcription by epoxyeicosatrienoic acids. J Biol Chem 2001; 276:15983-9. [PMID: 11279071 DOI: 10.1074/jbc.m100439200] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epoxyeicosatrienoic acids (EETs) are products of cytochrome P450 (CYP) epoxygenases that have vasodilatory and anti-inflammatory properties. Here we report that EETs have additional fibrinolytic properties. In vascular endothelial cells, physiological concentrations of EETs, particularly 11,12-EET, or overexpression of the endothelial epoxygenase, CYP2J2, increased tissue plasminogen activator (t-PA) expression by 2.5-fold without affecting plasminogen activator inhibitor-1 expression. This increase in t-PA expression correlated with a 4-fold induction in t-PA gene transcription and a 3-fold increase in t-PA fibrinolytic activity and was blocked by the CYP inhibitor, SKF525A, but not by the calcium-activated potassium channel blocker, charybdotoxin, indicating a mechanism that does not involve endothelial cell hyperpolarization. The t-PA promoter is cAMP-responsive, and induction of t-PA gene transcription by EETs correlated with increases in intracellular cAMP levels and, functionally, with cAMP-driven promoter activity. To determine whether increases in intracellular cAMP levels were due to modulation of guanine nucleotide-binding proteins, we assessed the effects of EETs on Galpha(s) and Galpha(i2). Treatment with EETs increased Galpha(s), but not Galpha(i2), GTP-binding activity by 3.5-fold. These findings indicate that EETs possess fibrinolytic properties through the induction of t-PA and suggest that endothelial CYP2J2 may play an important role in regulating vascular hemostasis.
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MESH Headings
- 8,11,14-Eicosatrienoic Acid/analogs & derivatives
- 8,11,14-Eicosatrienoic Acid/pharmacology
- Animals
- Aorta
- Atropine Derivatives
- Cattle
- Cells, Cultured
- Cyclic AMP/metabolism
- Cytochrome P-450 CYP2J2
- Cytochrome P-450 Enzyme System/metabolism
- Endothelium, Vascular/enzymology
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Gene Expression Regulation, Enzymologic/drug effects
- Gene Expression Regulation, Enzymologic/physiology
- Humans
- Oxygenases/metabolism
- Polymerase Chain Reaction
- Proadifen/pharmacology
- Promoter Regions, Genetic
- Saphenous Vein
- Tissue Plasminogen Activator/genetics
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
- Transfection
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Affiliation(s)
- K Node
- Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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22
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Singletary KW, Frey RS, Yan W. Effect of ethanol on proliferation and estrogen receptor-alpha expression in human breast cancer cells. Cancer Lett 2001; 165:131-7. [PMID: 11275361 DOI: 10.1016/s0304-3835(01)00419-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
There is substantial epidemiological evidence suggesting that alcohol consumption is associated with increased risk for breast cancer. However, possible biological mechanisms have not been clearly established. In the present studies, a direct effect of ethanol on the proliferation and intracellular content of cyclic AMP (cAMP) in two estrogen receptor-positive (ER+) and two estrogen receptor-negative (ER-) human breast cancer cell lines was examined. Treatment of ER+ human breast cancer cells (MCF-7 and ZR75.1) with ethanol at concentrations between 10 and 100 mM was associated with increased cell numbers compared to controls. The ERalpha content and the amount of intracellular cAMP also increased in ER+ cells exposed to ethanol, compared to controls. On the other hand, ethanol treatment did not increase cell proliferation or cAMP levels in the ER- (BT-20 and MDA-MB-231) human breast cancer cells. Therefore, ethanol added at physiologically relevant concentrations to ER+ human breast cancer cell cultures can enhance cell proliferation and increase the content of ERalpha.
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Affiliation(s)
- K W Singletary
- Department of Food Science and Human Nutrition, University of Illinois, 467 Bevier Hall, 905 South Goodwin Avenue, Urbana-Champaign, IL 61801, USA.
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23
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Zhang BH, Ho V, Farrell GC. Specific involvement of G(alphai2) with epidermal growth factor receptor signaling in rat hepatocytes, and the inhibitory effect of chronic ethanol. Biochem Pharmacol 2001; 61:1021-7. [PMID: 11286993 DOI: 10.1016/s0006-2952(01)00554-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have previously shown that chronic alcohol consumption inhibits liver regeneration by impairing epidermal growth factor receptor (EGFR)-operated phospholipase C-(gamma1) (PLC-(gamma1)) activation and the resultant rise in intracellular [Ca(2+)](i). In hepatocytes, activation of PLC-(gamma1) by EGFR requires involvement of a pertussis toxin-sensitive inhibitory guanine nucleotide-binding regulatory protein (G(alphai)) as an intermediate. In the present study, we first identified the G(alphai) protein isoform associated with the activated EGFR, and then examined whether the toxic effect of alcohol on EGFR signaling and liver cell proliferation was exerted on this association. In cultured hepatocytes from control rats, EGF rapidly induced association between EGFR and G(alphai2) but not other G(alphai) isoforms. In hepatocytes from rats fed alcohol for 16 weeks, EGF failed to stimulate this association of G(alphai2) with the EGFR. The impairment of EGFR-G(alphai2) complex formation caused by alcohol was associated with a decreased level of G(alphai2) in the plasma membrane fraction (approximately 50% control). Pertussis toxin, an inhibitor of G(alphai) function, produced an analogous disruption of the association between G(alphai2) and the EGFR, as well as inhibiting EGF-induced DNA synthesis. It is concluded that, in hepatocytes, G(alphai2) is specific among G(alphai) isoforms in coupling activation of the EGFR to other signaling pathways that control cell proliferation. Impaired coupling of G(alphai2) of EGFR could contribute to the mechanism by which chronic alcohol exposure inhibits liver regeneration.
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Affiliation(s)
- B H Zhang
- Storr Liver Unit, Department of Medicine and Westmead Millennium Institute, University of Sydney at Westmead Hospital, NSW 214, Westmead, Australia
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24
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Aldred A, Nagy LE. Ethanol dissociates hormone-stimulated cAMP production from inhibition of TNF-alpha production in rat Kupffer cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:G98-G106. [PMID: 9886984 DOI: 10.1152/ajpgi.1999.276.1.g98] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ethanol impairs hormone-stimulated cAMP production in a number of cell types, yet the effects of ethanol on downstream responses mediated by cAMP-dependent protein kinase (PKA) are not understood. Here we have investigated the effects of ethanol feeding on cAMP-mediated inhibition of tumor necrosis factor-alpha (TNF-alpha) synthesis in rat Kupffer cells. Male Wistar rats were fed liquid diets containing 36% of calories as ethanol for 4 wk or were pair fed a control diet. Stimulation of cAMP production by the adenosine A2 receptor agonist 5'-(N-ethylcarboxamido)-adenosine (NECA), prostaglandin E2, or forskolin was decreased to 25% of control values in Kupffer cells isolated from ethanol-fed rats. This decrease was associated with a reduction in the quantity of immunoreactive Gsalpha protein in ethanol-fed rats, with no changes observed in Gialpha or Gbeta. TNF-alpha production was higher in ethanol-fed rats in response to stimulation with lipopolysaccharide or latex beads. Despite the profound reduction in the ability of hormone to increase cAMP production, NECA and prostaglandin E2 inhibited TNF-alpha production to an equivalent degree in Kupffer cells from ethanol- and pair-fed rats. Total activity and immuoreactive protein quantity of PKA did not differ between groups. Activation of PKA in response to a 15-min treatment with 1 microM NECA was reduced by 50% in ethanol-fed rats compared with control. Despite this reduction in activation, translocation of the catalytic subunit of PKA to the nucleus and phosphorylation of cAMP response element binding protein in response to activation were observed in Kupffer cells from both ethanol- and pair-fed rats. These data demonstrate that there is a dissociation between ethanol-induced desensitization of hormone-stimulated cAMP production in rat Kupffer cells and the downstream inhibition of TNF-alpha production mediated by cAMP.
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Affiliation(s)
- A Aldred
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA
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25
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Tabakoff B, Hoffman PL. Adenylyl cyclases and alcohol. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1998; 32:173-93. [PMID: 9421591 DOI: 10.1016/s1040-7952(98)80011-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- B Tabakoff
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver 80262, USA
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26
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Karl PI, Divald A, Diehl AM, Fisher SE. Altered cyclic AMP-dependent human chorionic gonadotropin production in cultured human placental trophoblasts exposed to ethanol. Biochem Pharmacol 1998; 55:45-51. [PMID: 9413929 DOI: 10.1016/s0006-2952(97)00404-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chronic ethanol abuse during pregnancy can cause fetal injury, including the fetal alcohol syndrome (FAS). A contributing factor in this fetal injury may be the effect of ethanol on placental function. Previous studies have shown that ethanol treatment increases human chorionic gonadotropin (hCG) production by cultured human placental trophoblasts. In this study, we demonstrated that the stimulation of hCG production correlates with the ethanol concentration. Ethanol treatment enhanced intracellular adenosine 3':5'-cyclic monophosphate (cAMP) levels in response to either cholera toxin (CTX) or forskolin (FSK). Moreover, basal (i.e. unstimulated) cAMP levels were increased at 2 hr of ethanol exposure. However, this effect did not persist throughout the 24-hr incubation period. Therefore, ethanol treatment appears to induce increased hCG production, secondary to enhanced basal or stimulated cAMP production. The effect of ethanol was not associated with changes in Gs or Gi2 expression, as determined by northern blot and western blot analyses. In plasma membrane preparations from ethanol-treated cells, cAMP production was higher in response to Mn2+, a direct stimulator of adenylyl cyclase. Inclusion of Rp-cAMP, a protein kinase A inhibitor, eliminated the ethanol effect on hCG production. Treatment of cells with 8-Br-cAMP stimulated hCG production, but there was no difference between the ethanol-naive control and the ethanol-treated cells. These data suggest that ethanol treatment increases in vitro hCG production in human placental trophoblasts by enhancing cAMP production. Ethanol treatment appears to increase trophoblast adenylyl cyclase activity.
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Affiliation(s)
- P I Karl
- Department of Pediatrics, North Shore University Hospital-New York University School of Medicine, Manhasset, NY 11030, USA
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27
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Conway S, Garbouzova Y. Effect of fetal alcohol exposure on postnatal pituitary adenosine 3', 5'-cyclic phosphate content and growth hormone release. Alcohol Clin Exp Res 1996; 20:1212-20. [PMID: 8904974 DOI: 10.1111/j.1530-0277.1996.tb01115.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study examines the influence of fetal ethanol (ETOH) exposure and pair-feeding dams on postnatal, releasing factor-induced pituitary growth hormone (GH) release and adenosine 3',5'-cyclic phosphate (cAMP) accumulation. Fetuses were exposed to ETOH in utero by feeding dams a 36% (calories derived from ETOH: 6.6% v/v) ETOH liquid diet. Postnatal body weights were measured at sacrifice to evaluate the influence of ETOH on growth. Pituitary weight and protein content were measured to determine if changes in GH secretion or cAMP are proportional to the overall effect of ETOH on the pituitary. Pituitaries from 1-, 10-, and 60-day-old pups were explanted and incubated without hormones or with either somatostatin [somatotropin-release inhibiting factor (SRIF); 10(-9) M], or GH-releasing factor (GRF; 5 x 10(-9) M). Radioimmunoassays were used to determine tissue cAMP content, after extraction, and media GH concentration. Results indicate that fetal ETOH exposure specifically reduces the weight of both male and female pups. However, by 60 days of age, this reduction is not different from that found in pups of pair-fed controls, and both groups weighed less than pups of ad libitum controls. Furthermore, both pituitary weight and protein content were proportionately reduced in ETOH-exposed pups. In regard to releasing factor sensitivity, compared with pituitaries from ad libitum controls, the capacity of GRF to simulate GH release was diminished in 10-day-old males (p < 0.006) exposed to ETOH. On the other hand, the capacity of GRF to stimulate cAMP accumulation was generally enhanced by prenatal ETOH exposure. The capacity of SRIF to depress GH release was diminished in ETOH pups, compared with both pair-fed and ad libitum-fed controls (p < 0.0001). This difference in GH release was more apparent in pituitaries from females than males (p < 0.001). However, the depressed SRIF response was not associated with altered cAMP accumulation. These data suggest that fetal ETOH exposure has a sexually dimorphic effect on pituitary sensitivity to GH-releasing factors that may be related to altered regulation of GH release and susceptibility to growth retardation.
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Affiliation(s)
- S Conway
- Biology Department, Northern Illinois University, DeKalb 60115, USA
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Mauceri HJ, Becker KB, Conway S. The influence of ethanol exposure on insulin-like growth factor (IGF) type II receptors in fetal rat tissues. Life Sci 1996; 59:51-60. [PMID: 8684271 DOI: 10.1016/0024-3205(96)00257-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effect of ethanol (ETOH) exposure on the IGF type II receptor concentration was examined in 18 and 20 day fetal rat tissues. Pregnant dams were fed an ETOH (36% of calories derived from ETOH; 6.6% v/v) liquid diet. Control fetuses were offspring of dams either pair-fed a control liquid diet or ad libitum-fed a standard pelleted lab chow. Fetal brain, heart, kidney, liver, lung and skeletal muscle were removed and whole homogenates from individual animals were analyzed. Results of immunoquantification of IGF type II receptors in whole tissue homogenates show that there is a trend towards increased receptor concentration between 18 and 20 days in all tissue and this trend is significant for lung, liver and muscle. There were no significant differences in receptor concentration between treatment groups. These studies suggest that during the later stages of fetal development, there is an increase in total IGF type II receptors and this increase is undisturbed by ETOH exposure.
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Affiliation(s)
- H J Mauceri
- Department of Biological Sciences, Northern Illinois University, DeKalb 60115, USA
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Perkins RS, Lindsay MA, Barnes PJ, Giembycz MA. Early signalling events implicated in leukotriene B4-induced activation of the NADPH oxidase in eosinophils: role of Ca2+, protein kinase C and phospholipases C and D. Biochem J 1995; 310 ( Pt 3):795-806. [PMID: 7575412 PMCID: PMC1135968 DOI: 10.1042/bj3100795] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The early signalling events that may ultimately contribute to the assembly and subsequent activation of the NADPH oxidase in guinea-pig peritoneal eosinophils were investigated in response to leukotriene B4 (LTB4). LTB4 promoted a rapid, transient and receptor-mediated increase in the rate of H2O2 generation that was potentiated by R 59 022, a diradylglycerol (DRG) kinase inhibitor, implicating protein kinase C (PKC) in the genesis of this response. This conclusion was supported by the finding that the PKC inhibitor, Ro 31-8220, attenuated (by about 30%) the peak rate of LTB4-induced H2O2 generation under conditions where the same response evoked by 4 beta-phorbol 12,13-dibutyrate (PDBu) was inhibited by more than 90%. Paradoxically, Ro 31-8220 doubled the amount of H2O2 produced by LTB4 which may relate to the ability of PKC to inhibit cell signalling through phospholipase C (PLC). Indeed, Ro 31-8220 significantly enhanced LTB4-induced Ins(1,4,5)P3 accumulation and the duration of the Ca2+ transient in eosinophils. Experiments designed to assess the relative importance of DRG-mobilizing phospholipases in LTB4-induced oxidase activation indicated that phospholipase D (PLD) did not play a major role. Thus, although H2O2 generation was abolished by butan-1-ol, this was apparently unrelated to the inhibition of PLD, as LTB4 failed to stimulate the formation of Ptd[3H]BuOH in [3H]butan-1-ol-treated eosinophils. Rather, the inhibition was probably due to the ability of butan-1-ol to increase the eosinophil cyclic AMP content. In contrast, Ca(2+)- and PLC-driven mechanisms were implicated in H2O2 generation, as LTB4 elevated the Ins(1,4,5)P3 content and intracellular free Ca2+ concentration in intact cells, and cochelation of extracellular and intracellular Ca2+ significantly attenuated LTB4-induced H2O2 generation. Pretreatment of eosinophils with wortmannin did not affect LTB4-induced H2O2 production at concentrations at which it abolished the respiratory burst evoked by formylmethionyl-leucylphenylalanine in human neutrophils. Collectively, these data suggest that LTB4 activates the NADPH oxidase in eosinophils by PLD- and PtdIns 3-kinase-independent mechanisms that involve Ca2+, PLC and PKC. Furthermore, the activation of additional pathways that do not require Ca2+ is also suggested by the finding that LTB4 evoked a significant respiratory burst in Ca(2+)-depleted cells.
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Affiliation(s)
- R S Perkins
- Department of Thoracic Medicine, Royal Brompton National Heart and Lung Institute, London, U.K
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Iles KE, Nagy LE. Chronic ethanol feeding increases the quantity of Gαs-protein in rat liver plasma membranes. Hepatology 1995. [DOI: 10.1002/hep.1840210439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
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Kelly E, Harrison PK, Williams RJ. Effects of acute and chronic ethanol on cyclic AMP accumulation in NG108-15 cells: differential dependence of changes on extracellular adenosine. Br J Pharmacol 1995; 114:1433-41. [PMID: 7541691 PMCID: PMC1510298 DOI: 10.1111/j.1476-5381.1995.tb13366.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1. This study investigated the effects of acute and chronic ethanol on basal, agonist- and forskolin-stimulated cyclic AMP formation in NG108-15 mouse neuroblastoma x rat glioma hybrid cells, and examined the role of changes in extracellular adenosine concentrations on the effects observed. 2. NG108-15 cells incubated acutely with ethanol (1-200 mM) displayed concentration-dependent increases in basal and iloprost-stimulated (300 nM; a prostanoid IP receptor agonist) cyclic AMP accumulation but a concentration-dependent decrease in forskolin-stimulated (10 microM) accumulation. 3. Cells treated chronically with ethanol (200 mM) for 48 h displayed increases over control in basal, iloprost- (0.001-10 microM) and forskolin (0.01-100 microM)-stimulated cyclic AMP formation. However, chronic ethanol did not affect [3H]-iloprost binding to cell membranes. 4. Inclusion of adenosine deaminase (ADA; 1 unit ml-1) during the incubation period to measure cyclic AMP accumulation completely abolished the increase in basal accumulation following chronic ethanol, but did not affect the increase in iloprost stimulation. On the other hand ADA partially reversed the increase in forskolin stimulation following chronic ethanol, but even in the presence of high concentrations of ADA (5 units ml-1) the forskolin stimulation remained elevated above control. 5. Cells treated chronically with the adenosine receptor agonist 5'-(N-ethylcarboxamido)-adenosine (NECA; 10 microM for 48 h) displayed a reduction in subsequent NECA- and forskolin-stimulated cyclic AMP accumulation, but iloprost stimulation was not affected. ADA included acutely during the incubation period to measure cyclic AMP accumulation abolished the reduction in forskolin but not NECA stimulation produced by the chronic NECA pretreatment. 6. We have previously noted that ethanol inhibits NG108-15 cell proliferation and alters cell morphology.To mimic this, cells were incubated in the absence of foetal calf serum for 48 h. Following this time, basal, iloprost- and forskolin-stimulated cyclic AMP formation was enhanced over that in cells grown in the presence of serum.7. These results indicate that chronic ethanol enhances cyclic AMP formation in intact NG108-15 cells by more than one mechanism: one involves increased extracellular adenosine concentrations and the other a change in the transduction system beyond the receptor, possibly involving the adenylyl cyclase enzyme. Furthermore the ethanol-induced changes in cyclic AMP accumulation may relate to alterations in NG108-15 cell growth and development.
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Affiliation(s)
- E Kelly
- Department of Pharmacology, School of Medical Sciences, University of Bristol
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Malagolini N, Dall'Olio F, Turrini I, Cessi C, Serafini-Cessi F. Effect of ethanol on human colon carcinoma CaCo-2 and HT-29 cell lines during the maturation process. Alcohol Clin Exp Res 1994; 18:1386-91. [PMID: 7695034 DOI: 10.1111/j.1530-0277.1994.tb01440.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of the study was to ascertain whether the exposure to ethanol of human colon carcinoma CaCo-2 and HT-29 cell lines affects the differentiation process. As an index of enterocytic differentiation, the expression of sucrase, alkaline phosphatase, alpha 2,6-sialyltransferase toward the N-acetyllactosaminic sequence, and beta 1,4-N-acetylgalactosaminyltransferase (beta 1,4GalNAc-transferase) was examined. The latter enzyme is responsible for the biosynthesis of Sda carbohydrate histo-blood antigen, which mainly occurs in human colonic cells; its expression in CaCo-2 cells depends strictly on the enterocytic differentiation. The addition of ethanol in the culture medium resulted in a significant increment of sucrase and alpha 2,6-sialyltransferase activities in both cell lines, as well as the beta 1,4GalNAc-transferase activity in CaCo-2 cells and alkaline phosphatase activity in HT-29 cells. The increment was dose-dependent in the range between 50 and 200 mM ethanol and evident after 2 days of exposure in both cell systems. These results support the notion that, as occurs for cell lines of different origin, the ethanol in vitro positively affects the differentiation of intestinal cells, namely along the enterocytic lineage. The putative mechanism by which ethanol interferes with the maturation process of colonic cells is discussed.
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Affiliation(s)
- N Malagolini
- Dipartimento di Patologia Sperimentale, Università di Bologna, Italy
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Nagy LE. Role of adenosine A1 receptors in inhibition of receptor-stimulated cyclic AMP production by ethanol in hepatocytes. Biochem Pharmacol 1994; 48:2091-6. [PMID: 7802699 DOI: 10.1016/0006-2952(94)90509-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Brief exposure of primary cultures of hepatocytes to ethanol had a biphasic effect on glucagon receptor-dependent cyclic AMP (cAMP) production: 25-50 mM ethanol decreased cAMP levels, whereas treatment with 100-200 mM ethanol increased cAMP. This biphasic effect was also observed after pretreatment with 10 microM 4-methylpyrazole, an inhibitor of alcohol dehydrogenase. Adenosine A1 and A2 receptors in primary cultures of rat hepatocytes are coupled to inhibition and stimulation of adenylyl cyclase, respectively. Since primary cultures of hepatocytes release adenosine into their extracellular media, we tested whether the acute effects of ethanol on cAMP were mediated by extracellular adenosine. Co-incubation with 2 U/mL adenosine deaminase prevented inhibition of cAMP production by 25-50 mM ethanol, but had no effect on stimulation by 100-200 mM ethanol. Pretreatment of hepatocytes with 110 nM 8-cyclopentyl-1,3-dimethylxanthine, an adenosine A1 receptor antagonist, also completely blocked the inhibitory effects of ethanol on cAMP production. Low concentrations of ethanol enhanced the inhibitory effects of R(-)N6-(2-phenylisopropyl)adenosine, an A1 receptor agonist, on cAMP production in cells pretreated with adenosine deaminase to remove endogenous adenosine. These data suggest that endogenously produced adenosine can be an important modulator of the effects of ethanol on receptor-stimulated cAMP production in primary cultures of rat hepatocytes.
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Affiliation(s)
- L E Nagy
- Department of Nutritional Sciences, University of Guelph, Ontario, Canada
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Nagy LE, DeSilva SE. Adenosine A1 receptors mediate chronic ethanol-induced increases in receptor-stimulated cyclic AMP in cultured hepatocytes. Biochem J 1994; 304 ( Pt 1):205-10. [PMID: 7998934 PMCID: PMC1137473 DOI: 10.1042/bj3040205] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Cellular responses to adenosine depend on the distribution of the two adenosine receptor subclasses. In primary cultures of rat hepatocytes, adenosine receptors were coupled to adenylate cyclase via A1 and A2 receptors which inhibit and stimulate cyclic AMP production respectively. R-(-)-N6-(2-phenylisopropyl)-adenosine (R-PIA), the adenosine A1 receptor-selective agonist, inhibited glucagon-stimulated cyclic AMP production with an IC50 of 19 nM. This inhibition was blocked by the A1-specific antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPDX). 5'-N- Ethylcarboxamidoadenosine (NECA), an agonist which stimulates A2 receptors, increased cyclic AMP production with an EC50 of 0.6 microM. Treatment of primary cultures of rat hepatocytes with 100 mM ethanol for 48 h decreases the quantity and function of the inhibitory guanine-nucleotide regulatory protein (G(i)), resulting in a sensitization of receptor-stimulated cyclic AMP production [Nagy and deSilva (1992) Biochem. J. 286, 681-686]. When cells were cultured with 2 units/ml adenosine deaminase, to degrade extracellular adenosine, ethanol-induced increases in cyclic AMP production were completely prevented. Moreover, the specific A1-receptor antagonist, CPDX, also blocked the chronic effects of ethanol on receptor-stimulated cyclic AMP production. Treatment with adenosine deaminase or CPDX also prevented the decrease in quantity of the alpha subunit protein of G(i) observed in hepatocytes after chronic treatment with ethanol. Taken together, these results suggest that activation of adenosine A1 receptors on primary cultures of hepatocytes is involved in the development of chronic ethanol-induced sensitization of receptor-stimulated cyclic AMP production.
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Affiliation(s)
- L E Nagy
- Department of Nutritional Sciences, University of Guelph, ON, Canada
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Karl PI, Divald A, Fisher SE. Ethanol enhancement of ligand-stimulated cAMP production by cultured human placental trophoblasts. Biochem Pharmacol 1994; 48:1493-500. [PMID: 7945450 DOI: 10.1016/0006-2952(94)90575-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Chronic ethanol (EtOH) use during pregnancy can be associated with fetal injury including the fetal alcohol syndrome (FAS). A contributing factor in this fetal injury may be the effect of EtOH on the placenta. In this study, we have examined the effect of in vitro EtOH treatment on adenosine 3':5'-cyclic monophosphate (cAMP) production by cultured trophoblasts, in response to various ligands. Epinephrine (10(-6) M) rapidly stimulated cAMP with a peak between 2.5 and 5 min, which gradually returned to basal levels over 3-4 hr. EtOH treatment for > 16 hr resulted in an up-regulation of epinephrine-stimulated cAMP production. Inhibition of phosphodiesterase with Rolipram enhanced the effect of EtOH on cAMP production, suggesting that the effect of EtOH treatment was not due to phosphodiesterase inhibition. In cultured trophoblasts, EtOH treatment increased both epinephrine and 16,16'-dimethylprostaglandin E2 (dm-PGE2)-dependent cAMP production at varying ligand concentrations, suggesting an increased capacity to respond. When trophoblasts were treated with forskolin, a stimulator of adenylyl cyclase, cAMP production was enhanced in EtOH-treated cells. This suggests that EtOH treatment enhances adenylyl cyclase activity in these intact, cultured cells. Unlike trophoblasts from term human placenta, JAR choriocarcinoma cells did not respond to epinephrine, adenosine, or dm-PGE2. The choriocarcinoma cells appeared to have lost the ability to respond to these ligands. Although the JAR cell adenylyl cyclase was stimulated by forskolin, EtOH treatment did not alter forskolin-stimulated cAMP production. In summary, EtOH-induced up-regulation of cAMP production appears to be cell specific, being present in normal human trophoblasts but not in undifferentiated choriocarcinoma cells.
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Affiliation(s)
- P I Karl
- Department of Pediatrics, North Shore University Hospital, Cornell University Medical College, Manhasset, NY 11030
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Novotny J, Kvapil P, Cello J, Ransnäs LA. Coxsackievirus B3 entry into the host cell interferes with G-protein-mediated transmembrane signalling. Biosci Rep 1994; 14:205-14. [PMID: 7849242 DOI: 10.1007/bf01200249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In the present work we used various cell lines in order to study the possible effect of coxsackievirus B3 (CVB3) entry on the adenylyl cyclase transmembrane signalling system. A significant decrease (by about 10-20%) was found in forskolin-augmented as well as in A1F-4- and GTP gamma S-sensitive adenylyl cyclase activity in plasma membranes isolated from HeLa, HEp-2, Vero and green monkey kidney cells shortly (up to 60 min) preincubated with CVB3 (5 PFU/cell). Moreover, the ability of G-proteins derived from plasma membranes of infected cells to reconstitute AC activity in the cyc- mutant of S49 cells was also reduced. Content of G-protein subunits, however, remained unchanged after CVB3 attachment. Functional alterations in the G-protein-mediated adenylyl cyclase signalling system were accompanied by a marked decrease (by about 20-40%) of intracellular cAMP levels in virus-affected cells. These findings demonstrate clearly that CVB3 may affect functioning of the G-protein regulated adenylyl cyclase transmembrane signalling system in virus-sensitive cells as early as during the first period of its contact with the cellular plasma membrane.
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Affiliation(s)
- J Novotny
- Wallenberg Laboratory for Cardiovascular Research, Gothenburg University, Sweden
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