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Babcock J, Herrera A, Coricor G, Karch C, Liu AH, Rivera-Gines A, Ko JL. Mechanism Governing Human Kappa-Opioid Receptor Expression under Desferrioxamine-Induced Hypoxic Mimic Condition in Neuronal NMB Cells. Int J Mol Sci 2017; 18:ijms18010211. [PMID: 28117678 PMCID: PMC5297840 DOI: 10.3390/ijms18010211] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Revised: 01/03/2017] [Accepted: 01/11/2017] [Indexed: 12/30/2022] Open
Abstract
Cellular adaptation to hypoxia is a protective mechanism for neurons and relevant to cancer. Treatment with desferrioxamine (DFO) to induce hypoxia reduced the viability of human neuronal NMB cells. Surviving/attached cells exhibited profound increases of expression of the human kappa-opioid receptor (hKOR) and hypoxia inducible factor-1α (HIF-1α). The functional relationship between hKOR and HIF-1α was investigated using RT-PCR, Western blot, luciferase reporter, mutagenesis, siRNA and receptor-ligand binding assays. In surviving neurons, DFO increased HIF-1α expression and its amount in the nucleus. DFO also dramatically increased hKOR expression. Two (designated as HIFC and D) out of four potential HIF response elements of the hKOR gene (HIFA-D) synergistically mediated the DFO response. Mutation of both elements completely abolished the DFO-induced effect. The CD11 plasmid (containing HIFC and D with an 11 bp spacing) produced greater augmentation than that of the CD17 plasmid (HIFC and D with a 17 bp-spacing), suggesting that a proper topological interaction of these elements synergistically enhanced the promoter activity. HIF-1α siRNA knocked down the increase of endogenous HIF-1α messages and diminished the DFO-induced increase of hKOR expression. Increased hKOR expression resulted in the up-regulation of hKOR protein. In conclusion, the adaptation of neuronal hKOR under hypoxia was governed by HIF-1, revealing a new mechanism of hKOR regulation.
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Affiliation(s)
- Jennifer Babcock
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - Alberto Herrera
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - George Coricor
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - Christopher Karch
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - Alexander H Liu
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - Aida Rivera-Gines
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
| | - Jane L Ko
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA.
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Hunkele A, Sultan H, Ikalina FA, Liu AH, Nahar-Gohad P, Ko JL. Identification of gamma-synuclein as a new PCBP1-interacting protein. Neurol Res 2016; 38:1064-1078. [PMID: 26344801 DOI: 10.1179/1743132815y.0000000091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES PolyC binding protein 1 (PCBP1) is a transcriptional regulator of human mu-opioid receptor (hMOR) gene in the CNS and is also related to cancer/diseases. It possesses multi-roles that can be mediated by protein-protein interactions. To understand the mechanism controlling PCBP1 functions, PCBP1-interacting protein was investigated. METHODS Using PCBP1 as the bait, a human brain cDNA library was screened via two-hybrid system. DNA sequence of candidate protein was confirmed using NCBI/SNP databases. Candidate protein in various cell lines was examined by RT-PCR. Glutathione-S-transferase (GST) pull-down and co-immunoprecipitation were used to validate the physical interaction. Its effects on hMOR gene regulation were examined. RESULTS One clone was identified as gamma-synuclein110E, an SNP of gamma-synuclein110V. The interaction between PCBP1 and gamma-synuclein110E was confirmed by further validation and GST pull-down assay. Confocal analysis showed gamma-synuclein110E mainly expressing in the cytosol of human neuronal NMB cells. This interaction was confirmed by co-immunoprecipitation with NMB lysates, containing both proteins endogenously. Ectopic expression of gamma-synuclein110E or 110V did not alter hMOR mRNA level or promoter activity, suggesting no involvement of gamma-synuclein in modulating hMOR expression. Co-immunoprecipitation using gamma-synuclein110E or 110V overexpressed NMB cells with anti-PCBP1 antibody revealed a stronger intensity of co-immunoprecipitated gamma-synuclein band using gamma-synuclein110E-overexpressed cells as compared to that using gamma-synuclein110V-overexpressed cells. Synuclein110E was also identified in H292 (lung), HT29 (colon) and T47D (breast) cells, and this physical interaction was confirmed. CONCLUSION We report a newly identified PCBP1-interacting protein, gamma-synuclein110E, and provide some insight into its complex role as well as discuss potential roles of this interaction.
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Affiliation(s)
- Amanda Hunkele
- a Department of Biological Sciences ; Seton Hall University , USA
| | - Hamidah Sultan
- a Department of Biological Sciences ; Seton Hall University , USA
| | - Faith A Ikalina
- a Department of Biological Sciences ; Seton Hall University , USA
| | - Alexander H Liu
- a Department of Biological Sciences ; Seton Hall University , USA
| | | | - Jane L Ko
- a Department of Biological Sciences ; Seton Hall University , USA
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Nahar-Gohad P, Sultan H, Esteban Y, Stabile A, Ko JL. RACK1 identified as the PCBP1-interacting protein with a novel functional role on the regulation of human MOR gene expression. J Neurochem 2012; 124:466-77. [PMID: 23173782 DOI: 10.1111/jnc.12100] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Revised: 11/10/2012] [Accepted: 11/14/2012] [Indexed: 12/23/2022]
Abstract
Poly C binding protein 1 (PCBP1) is an expressional regulator of the mu-opioid receptor (MOR) gene. We hypothesized the existence of a PCBP1 co-regulator modifying human MOR gene expression by protein-protein interaction with PCBP1. A human brain cDNA library was screened using the two-hybrid system with PCBP1 as the bait. Receptor for activated protein kinase C (RACK1) protein, containing seven WD domains, was identified. PCBP1-RACK1 interaction was confirmed via in vivo validation using the two-hybrid system, and by co-immunoprecipitation with anti-PCBP1 antibody and human neuronal NMB cell lysate, endogenously expressing PCBP1 and RACK1. Further co-immunoprecipitation suggested that RACK1-PCBP1 interaction occurred in cytosol alone. Single and serial WD domain deletion analyses demonstrated that WD7 of RACK1 is the key domain interacting with PCBP1. RACK1 over-expression resulted in a dose-dependent decrease of MOR promoter activity using p357 plasmid containing human MOR promoter and luciferase reporter gene. Knock-down analysis showed that RACK1 siRNA decreased the endogenous RACK1 mRNA level in NMB, and elevated MOR mRNA level as indicated by RT-PCR. Likewise, a decrease of RACK1 resulted in an increase of MOR proteins, verified by (3) H-diprenorphine binding assay. Collectively, this study reports a novel role of RACK1, physically interacting with PCBP1 and participating in the regulation of human MOR gene expression in neuronal NMB cells.
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Affiliation(s)
- Pranjal Nahar-Gohad
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, USA
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4
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Acute and chronic exercise modulates the expression of MOR opioid receptors in the hippocampal formation of rats. Brain Res Bull 2010; 83:278-83. [PMID: 20655988 DOI: 10.1016/j.brainresbull.2010.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 07/08/2010] [Accepted: 07/13/2010] [Indexed: 11/21/2022]
Abstract
Exercise stimulates the release of beta-endorphin and other endogenous opioid peptides that are believed to be responsible for changes in mood, perception of pain and also performance. Although the vast majority of literature data support the role of physical exercise in increasing beta-endorphin levels, indirect measures such as increased endorphin levels in peripheral blood do not reflect opioid levels in the central nervous system. The purpose of the present study was to verify whether acute and chronic exercise using both voluntary and forced exercise procedures could modify the expression of μ-opioid receptors (MOR) in rat hippocampal formation. Immunoblotting analysis showed significantly enhanced MOR expression in the hippocampal formation in the acute (forced and voluntary) exercise groups when compared to the control group. Conversely, a significant reduction of MOR expression was noted in the chronic forced and chronic voluntary exercise groups compared to the acute forced and voluntary groups respectively. MOR expression was not significantly different in rats trained using both acute or chronic exercise. Immunohistochemistry analysis showed a higher number of MOR-positive cells for acute forced and voluntary exercise groups in the CA1, CA3, hilus and dentate gyrus regions compared to the control group. Our findings indicate that acute and chronic exercise modulates MOR expression in the hippocampal formation of rats.
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Cook RJ, Karch C, Nahar P, Rivera A, Ko JL. Effects of desferoxamine-induced hypoxia on neuronal human mu-opioid receptor gene expression. Biochem Biophys Res Commun 2010; 398:56-61. [PMID: 20558138 DOI: 10.1016/j.bbrc.2010.06.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2010] [Accepted: 06/08/2010] [Indexed: 11/29/2022]
Abstract
The effect of desferoxamine (DFO)-induced hypoxia on neuronal human mu-opioid receptor (hMOR) gene expression was investigated using NMB cells. DFO decreased cell viability and increased cellular glutathione levels in a dose- and time-dependent manner. Confocal analysis using annexin-V-fluorescein and propidium iodide staining revealed that surviving/attached cells under DFO challenge were morphologically similar to control (vehicle-treated) cells. RT-PCR analysis demonstrated that the hypoxia inducible factor-1alpha (HIF-1alpha) mRNA level was augmented in these surviving neurons. DFO treatment for 8h or longer down-regulated the hMOR message, but not that of the delta-opioid receptor. Functional analysis using luciferase reporter assay showed that the hMOR 5'-regulatory region, from -357bp to translational initiation site (+1), contains the active promoter with an inhibitory region located in the -422 to -357bp region. DFO decreased hMOR promoter activity as compared to control. Mutation analysis suggested the existence of both dsDNA and ssDNA elements, located in a CT-rich region of hMOR, mediating the DFO-response. RT-PCR further revealed that DFO exhibited no effect on hMOR mRNA stability. In conclusion, DFO-induced hypoxia specifically affects neuronal hMOR gene expression at the transcriptional, not post-transcriptional, level.
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Affiliation(s)
- Ryan J Cook
- Department of Biological Sciences, Seton Hall University, South Orange, NJ 07079, United States
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Agonist-specific down regulation of mu-opioid receptors: Different cellular pathways are activated by different opioid agonists. Life Sci 2008; 82:831-9. [PMID: 18358497 DOI: 10.1016/j.lfs.2008.01.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Revised: 01/17/2008] [Accepted: 01/23/2008] [Indexed: 11/21/2022]
Abstract
Opioid agonists are known to induce down regulation of opioid receptors through the classical pathway that involves phosphorylation, clathrin-dependent endocytosis and lysosomal/endosomal degradation of the internalized receptors. As expected, exposure of mu-opioid receptor (MOR)-transfected HEK-293 cells to either DAMGO (a specific mu-opioid agonist) or etorphine (a wide spectrum opioid agonist) resulted in down regulation of the receptors that was blocked by the kinase inhibitor staurosporine, by hypertonic sucrose and by the lysosomal and proteasomal inhibitors chloroquine and lactacystin. High concentration of etorphine, but not of DAMGO, induced an additional process of down regulation that was resistant to staurosporine, to hypertonic sucrose and to chloroquine-lactacystin. Etorphine, but not DAMGO, also induced down regulation of mu-opioid receptors in isolated membranes of HEK cells. This membrane-delimited down regulation was blocked by selective inhibitors of protease enzymes, suggesting the involvement of membranous serine- and amino-peptidases. This membranous down regulation of opioid receptors was dependent on the concentration of etorphine and was blocked by the opioid antagonist naloxone. Etorphine induced similar down regulation in membranes of HEK-293 cells transfected with delta-opioid receptors (DOR) as well in membranes of cells that endogenously express opioid receptors. This agonist-specific membrane-delimited regulatory process appears to be physiologically relevant and should be taken into account when studying long term effects of opioid drugs.
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Smith MA, Yancey DL. Sensitivity to the effects of opioids in rats with free access to exercise wheels: mu-opioid tolerance and physical dependence. Psychopharmacology (Berl) 2003; 168:426-34. [PMID: 12709780 DOI: 10.1007/s00213-003-1471-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2002] [Accepted: 03/08/2003] [Indexed: 12/01/2022]
Abstract
RATIONALE Exercise stimulates the release of endogenous opioid peptides and increases nociceptive (i.e. pain) thresholds in both human and animal subjects. During chronic, long-term exercise, sensitivity to the effects of morphine and other mu opioids decreases, leading some investigators to propose that exercise may lead to the development of cross tolerance to exogenously administered opioid agonists. OBJECTIVE The purpose of the present investigation was to examine the effects of chronic exercise on sensitivity to mu opioids, and to determine whether these effects can be attributed to the development of opioid tolerance and dependence. METHODS Rats were obtained at weaning and housed singly in standard polycarbonate cages (sedentary) or modified cages equipped with exercise wheels (exercise). After 6 weeks under these conditions, opioids possessing a range of relative efficacy at the mu receptor (morphine, levorphanol, buprenorphine, butorphanol, nalbuphine) were examined in a warm-water tail-withdrawal procedure. RESULTS Morphine, levorphanol and buprenorphine produced maximal levels of antinociception in both groups of rats, but all were more potent in sedentary rats than in exercising rats. Butorphanol and nalbuphine produced maximal levels of antinociception in sedentary rats under some conditions in which they failed to produce antinociception in exercising rats. Sensitivity to the effects of buprenorphine was decreased in sedentary rats that were transferred to cages equipped with exercise wheels, and increased in exercising rats that were transferred to sedentary housing conditions. In the latter group, exercise output prior to housing reassignment was positively correlated with increases in sensitivity to buprenorphine following housing reassignment. Naloxone administration precipitated a mild withdrawal syndrome in exercising rats that was not readily apparent in sedentary rats. CONCLUSIONS These data suggest that chronic exercise leads to the development of mu-opioid tolerance and physical dependence, and that these effects are similar to those produced by chronic opioid administration.
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Affiliation(s)
- Mark A Smith
- Department of Psychology, Davidson College, Davidson, NC 28035-7037, USA.
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Im HJ, Smirnov D, Yuhi T, Raghavan S, Olsson JE, Muscat GE, Koopman P, Loh HH. Transcriptional modulation of mouse mu-opioid receptor distal promoter activity by Sox18. Mol Pharmacol 2001; 59:1486-96. [PMID: 11353810 DOI: 10.1124/mol.59.6.1486] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Previously, we reported the presence of dual promoters, referred to as distal (DP) and proximal, with a negative regulatory element between them in the mouse mu-opioid receptor (mor) gene. Here we have identified a positive regulatory element influencing mor DP transcription, which contains multiple consensus binding motifs for Sox factors (sex-determining Sry-like high mobility group box-containing genes). In gel supershift assays, the Sox family member Sox18 bound directly to the multiple Sox consensus binding motifs of the mor DP enhancer. Overexpression of Sox18 cDNA increased luciferase activity regulated by the mor DP, and did so in a Sox18 concentration-dependent manner. In contrast, overexpression of another Sox member, Sox5, triggered no such trans-activation of mor DP-driven luciferase activity or DNA-protein binding activity. These results suggest that Sox18 directly and specifically stimulates mor gene expression, by trans-activating the mor DP enhancer.
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MESH Headings
- 5' Untranslated Regions/genetics
- Amino Acid Motifs
- Animals
- Binding Sites
- CHO Cells
- Consensus Sequence/genetics
- Cricetinae
- Dose-Response Relationship, Drug
- Enhancer Elements, Genetic/genetics
- Gene Targeting
- Genes, Reporter
- HeLa Cells
- High Mobility Group Proteins/antagonists & inhibitors
- High Mobility Group Proteins/genetics
- High Mobility Group Proteins/physiology
- Humans
- Mice
- Oligonucleotides, Antisense/pharmacology
- Promoter Regions, Genetic/genetics
- Protein Processing, Post-Translational
- Receptors, Opioid, mu/genetics
- SOXF Transcription Factors
- Transcription Factors/antagonists & inhibitors
- Transcription Factors/genetics
- Transcription Factors/physiology
- Transcription, Genetic/genetics
- Transcriptional Activation/genetics
- Tumor Cells, Cultured
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Affiliation(s)
- H J Im
- Department of Pharmacology, The University of Minnesota Medical School, 6-120 Jackson Hall, 321 Church St. S.E., Minneapolis, MN 55455, USA.
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9
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Keren O, Gafni M, Sarne Y. Potentiation of transmitter release from NMB human neuroblastoma cells by kappa-opioids is mediated by N-type voltage-dependent calcium channels. Brain Res 1999; 843:193-8. [PMID: 10528125 DOI: 10.1016/s0006-8993(99)01904-6] [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: 11/23/2022]
Abstract
The selective kappa-opioid agonist trans-(+/-)-3, 4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl] benzenacetamidemethansulfonate (U50,488) potentiates both basal and depolarization-evoked [3H]dopamine release from NMB cells. The potentiation of dopamine release by U50,488 is mediated by N-type voltage-dependent calcium channels since it is blocked by omega-conotoxin, and is resistant to pertussis toxin (PTX)-treatment. When the stimulation of release by U50,488 is blocked by the N-channel antagonist omega-conotoxin, an inhibitory effect on dopamine release is revealed, suggesting that stimulatory and inhibitory effects of U50,488 are exerted in parallel.
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MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels, N-Type/drug effects
- Calcium Channels, N-Type/physiology
- Dopamine/metabolism
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Enkephalin, Leucine/analogs & derivatives
- Enkephalin, Leucine/pharmacology
- Humans
- Neuroblastoma
- Pertussis Toxin
- Potassium Cyanide/pharmacology
- Receptors, Opioid, kappa/agonists
- Tumor Cells, Cultured
- Virulence Factors, Bordetella/pharmacology
- omega-Conotoxins/pharmacology
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Affiliation(s)
- O Keren
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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10
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Chen HC, Wei LN, Loh HH. Expression of mu-, kappa- and delta-opioid receptors in P19 mouse embryonal carcinoma cells. Neuroscience 1999; 92:1143-55. [PMID: 10426553 DOI: 10.1016/s0306-4522(99)00030-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
P19 embryonal carcinoma cells are pluripotential and able to differentiate into a variety of cell types, including neurons, glia and fibroblast-like cells, upon retinoic acid treatment and cellular aggregation. Using reverse transcription-polymerase chain reaction, ligand binding and immunocytochemical methods, kappa- and delta-opioid receptors were detected in undifferentiated P19 cells. The mu-opioid receptor was not observed until one day after plating, following one essential step of differentiation, but increased in number in the four days after plating. Several different expression patterns were detected in these differentiated cells. Some cells exhibited mu- and delta-opioid receptors co-expressed, with or without K-opioid receptor; whereas some of the cells expressed only K-opioid receptor. All three opioid receptors are detected on aggregated cells which are postmitotic and also expressing neurofilaments, indicating neuronal characteristics. Furthermore, those cells expressing mu and delta-opioid receptors also expressed glutamate decarboxylase, characteristic of the GABAergic phenotype. Based on these findings, we propose that P19 cells may serve as a model system to study the developmental regulation of opioid receptors, and in particular their relationship with GABA.
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MESH Headings
- Animals
- Carcinoma, Embryonal/genetics
- Carcinoma, Embryonal/metabolism
- Carcinoma, Embryonal/pathology
- Immunohistochemistry
- Mice
- Phenotype
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Tissue Distribution/physiology
- Tumor Cells, Cultured
- gamma-Aminobutyric Acid/metabolism
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Affiliation(s)
- H C Chen
- Department of Pharmacology, University of Minnesota, Minneapolis 55455, USA
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11
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Choe CY, Im HJ, Ko JL, Loh HH. Mouse mu opioid receptor gene expression. A 34-base pair cis-acting element inhibits transcription of the mu opioid receptor gene from the distal promoter. J Biol Chem 1998; 273:34926-32. [PMID: 9857022 PMCID: PMC3001105 DOI: 10.1074/jbc.273.52.34926] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 5'-flanking region of the mouse mu opioid receptor (MOR) gene has two promoters, referred to as distal and proximal, and the activities of each in the brain are quite different from each other. The 5'-distal promoter regulatory sequences (5'-DPRS), positioned between these two promoters, have strong inhibitory effects on the reporter gene expression driven by the MOR distal promoter. In our studies, detailed 3' deletion mapping of the 5'-DPRS narrowed down the negative cis-acting element to a 34-base pair (bp) segment (position -721 to -687). This 34-bp cis-acting element functions in both neuronal (NMB) and non-neuronal (CHO and RAW264.7) cultured cells. S1 nuclease protection assays indicated that this 34-bp cis-acting element suppresses distal promoter activity at the transcriptional level. Linker scanning mutagenesis demonstrated that nucleotides around position -721 and -689 in the 34-bp cis-acting element are essential for the regulation of distal promoter activity. Operational characterization of the 34-bp cis-acting element in the homologous MOR distal promoter and the heterologous SV40 promoter showed that its effects are position- and promoter-dependent while being orientation-independent in both promoters. Collectively, these data suggested that this 34-bp segment is a conditional transcriptional cis-acting element that blocks mouse MOR gene expression from the distal promoter.
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Affiliation(s)
- C y Choe
- Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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12
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Shapira M, Gafni M, Sarne Y. Independence of, and interactions between, cannabinoid and opioid signal transduction pathways in N18TG2 cells. Brain Res 1998; 806:26-35. [PMID: 9739102 DOI: 10.1016/s0006-8993(98)00697-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
N18TG2 neuroblastoma cells co-express delta-opioid and CB1-cannabinoid receptors. Both receptors are negatively coupled to adenylyl cyclase through pertussis toxin-sensitive GTP-binding proteins. In the present study, we confirmed the independent activity of opioid and cannabinoid agonists, and investigated chronic interactions between the two signal transduction pathways in these cells. Opioid and cannabinoid agonists stimulated [35S]guanosine-5'-O-(3-thiotriphosphate) binding to N18TG2 membranes. When the opioid agonist etorphine and the cannabinoid agonist desacetyllevonantradol (DALN) were applied together, the stimulation was similar to the arithmetic sum of the two separate effects. This additivity existed even after partial ablation of the G-proteins reservoir with a low concentration of pertussis toxin, indicating that opioid and cannabinoid receptors activate different pools of G-proteins in N18TG2 cells. Chronic treatment of the cells with either opioid or cannabinoid agonists induced desensitization to the respective drug. In addition, asymmetric cross-desensitization was found: while long-term exposure to DALN induced homologous desensitization, and did not reduce the effect of etorphine, long-term exposure to etorphine attenuated the cannabinoid activation of G-proteins. Chronic exposure to either DALN or etorphine not only induced desensitization, but also elevated the basal activity of G-proteins in the exposed cells. The combination of the two drugs did not yield an additive activation, suggesting that chronic exposure of N18TG2 cultures to cannabinoid and opioid agonists modified a common responding element within the cells. This work presents the N18TG2 neuroblastoma as a suitable experimental model to study the molecular mechanism(s) underlying chronic interactions between opioid and cannabinoid drugs.
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Affiliation(s)
- M Shapira
- The Mauerberger Chair in Neuropharmacology, Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
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13
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Shapira M, Baumhaker Y, Sarne Y. Long-term regulation of opioid receptors in neuroblastoma and lymphoma cell lines. J Neuroimmunol 1997; 76:145-52. [PMID: 9184644 DOI: 10.1016/s0165-5728(97)00046-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Long-term regulation of opioid binding was studied in the human neuroblastoma NMB and in the murine lymphoma R1.1 and R1.EGO cell lines. Binding was down-regulated following prolonged exposure to opioid agonists and up-regulated following exposure to antagonist. Down-regulation was inhibited by the metabolic blocker sodium-azide and by the protein kinase H-7. Up-regulation was blocked by the protein and mRNA synthesis blockers cycloheximide, alpha-amanitin and actinomycin D. A significant difference was found between the response of neuronal and immune cells to ethanol exposure: while opioid binding in neuroblastoma culture underwent a pronounced (75%) up-regulation, no effect of ethanol on opioid receptors in lymphoma cultures was detected. The described cell lines present an excellent experimental model to study long-term regulation of opioid receptors in the nervous and immune systems and to elucidate the biological effects of chronic use of opiates and alcohol.
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Affiliation(s)
- M Shapira
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Israel
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