1
|
Brejchova J, Holan V, Svoboda P. Expression of Opioid Receptors in Cells of the Immune System. Int J Mol Sci 2020; 22:E315. [PMID: 33396783 PMCID: PMC7795304 DOI: 10.3390/ijms22010315] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/19/2020] [Accepted: 12/22/2020] [Indexed: 01/04/2023] Open
Abstract
The observation of the immunomodulatory effects of opioid drugs opened the discussion about possible mechanisms of action and led researchers to consider the presence of opioid receptors (OR) in cells of the immune system. To date, numerous studies analyzing the expression of OR subtypes in animal and human immune cells have been performed. Some of them confirmed the expression of OR at both the mRNA and protein level, while others did not detect the receptor mRNA either. Although this topic remains controversial, further studies are constantly being published. The most recent articles suggested that the expression level of OR in human peripheral blood lymphocytes could help to evaluate the success of methadone maintenance therapy in former opioid addicts, or could serve as a biomarker for chronic pain diagnosis. However, the applicability of these findings to clinical practice needs to be verified by further investigations.
Collapse
Affiliation(s)
- Jana Brejchova
- Laboratory of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, 14220 Prague, Czech Republic;
| | - Vladimir Holan
- Department of Nanotoxicology and Molecular Epidemiology, Institute of Experimental Medicine of the Czech Academy of Sciences, 14220 Prague, Czech Republic;
- Department of Cell Biology, Faculty of Science, Charles University, 12843 Prague, Czech Republic
| | - Petr Svoboda
- Laboratory of Biomathematics, Institute of Physiology of the Czech Academy of Sciences, 14220 Prague, Czech Republic;
| |
Collapse
|
2
|
LaVigne J, Keresztes A, Chiem D, Streicher JM. The endomorphin-1/2 and dynorphin-B peptides display biased agonism at the mu opioid receptor. Pharmacol Rep 2020; 72:465-471. [PMID: 32112361 DOI: 10.1007/s43440-020-00061-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/09/2020] [Accepted: 01/30/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Opioid agonist activation at the mu opioid receptor (MOR) can lead to a wide variety of physiological responses. Many opioid agonists share the ability to selectively and preferentially activate specific signaling pathways, a term called biased agonism. Biased opioid ligands can theoretically induce specific physiological responses and might enable the generation of drugs with improved side effect profiles. METHODS Dynorphins, enkephalins, and endomorphins are endogenous opioid agonist peptides that may possess distinct bias profiles; biased agonism of endogenous peptides could explain the selective roles of these ligands in vivo. Our purpose in the present study was to investigate biased signaling and potential underlying molecular mechanisms of bias using 35S-GTPγS and cAMP assays, specifically focusing on the role of adenylyl cyclases (ACs) and regulators of G-protein signaling proteins (RGSs) in CHO, N2a, and SH-SY5Y cell lines, all expressing the human MOR. RESULTS We found that endomorphin-1/2 preferentially activated cAMP signaling, while dynorphin-B preferentially activated 35S-GTPγS signaling in most cell lines. Experiments carried out in the presence of an isoform selective RGS-4 inhibitor, and siRNA knockdown of AC6 in N2a cells did not significantly affect the bias properties of endomorphins, suggesting that these proteins may not play a role in endomorphin bias. CONCLUSION We found that endomorphin-1/2 and dynorphin-B displayed contrasting bias profiles at the MOR, and ruled out potential AC6 and RGS4 mechanisms in this bias. This identified signaling bias could be involved in specifying endogenous peptide roles in vivo, where these peptides have low selectivity between opioid receptor family members.
Collapse
Affiliation(s)
- Justin LaVigne
- Department of Pharmacology, College of Medicine, University of Arizona, Box 245050, LSN563, 1501 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Attila Keresztes
- Department of Pharmacology, College of Medicine, University of Arizona, Box 245050, LSN563, 1501 N. Campbell Ave., Tucson, AZ, 85724, USA
| | - Daniel Chiem
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, ME, 04005, USA
| | - John M Streicher
- Department of Pharmacology, College of Medicine, University of Arizona, Box 245050, LSN563, 1501 N. Campbell Ave., Tucson, AZ, 85724, USA.
| |
Collapse
|
3
|
Ding Z, Ejendal KFK, Soto-Velasquez M, Hayes MP, Santoro N, Larsen MJ, Watts VJ. Genome-Wide Small Interfering RNA Screening Reveals a Role for Cullin3-Really Interesting New Gene Ligase Signaling in Heterologous Sensitization of Adenylyl Cyclase. J Pharmacol Exp Ther 2019; 372:267-276. [PMID: 31857349 DOI: 10.1124/jpet.119.261255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 12/12/2019] [Indexed: 12/18/2022] Open
Abstract
Heterologous sensitization of adenylyl cyclase (AC) is revealed as enhanced or exaggerated AC/cAMP signaling that occurs following persistent activation of Gα i/o-coupled receptors. This paradoxical phenomenon was discovered more than 40 years ago and was proposed as a cellular mechanism to explain the adaptive changes that occur following chronic exposure to drugs of abuse. However, the underlying molecular mechanisms of heterologous sensitization of AC remain largely unknown. In the present study, we performed a genome-wide cell-based RNA interference screen as an unbiased approach to identify genes associated with heterologous sensitization of AC. Following a series of validation and confirmation assays, three genes that form an E3 ligase complex, cullin3 (CUL3), neural precursor-cell-expressed and developmentally downregulated 8 (NEDD8), and really interesting new gene (RING)-box protein 1 (RBX1), were identified as specific modulators of heterologous sensitization of AC. Furthermore, based on the downstream actions of these genes, we evaluated the activity of proteasome inhibitors as well as the specific NEDD8-activating enzyme inhibitor, MLN4924 (Pevonedistat), in AC sensitization. We demonstrate that MG-132 and bortezomib treatments could mimic the inhibitory effects observed with gene knockdown, and MLN4924 was potent and efficacious in blocking the development of heterologous sensitization of endogenous and recombinant AC isoforms, including AC1, AC2, AC5, and AC6. Together, by using genetic and pharmacological approaches, we identified, for the first time, cullin3-RING ligases and the protein degradation pathway as essential modulators for heterologous sensitization of AC. SIGNIFICANCE STATEMENT: Through a genome-wide cell-based RNA interference screening, we identified three genes that form an E3 ligase complex, cullin3, neural precursor-cell-expressed and developmentally downregulated 8 (NEDD8), and really interesting new gene-box protein 1, as specific modulators of heterologous sensitization of AC. The effect of cullin3, NEDD8, or really interesting new gene-box protein 1 small interfering RNAs on heterologous sensitization was recapitulated by proteasome inhibitors, MG132 and bortezomib, and the specific NEDD8-activating enzyme inhibitor, MLN4924. These results suggest a novel hypothesis in which protein degradation is involved in the sensitization of AC signaling that occurs following chronic activation of Gαi/o-coupled receptors.
Collapse
Affiliation(s)
- Zhong Ding
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Karin F K Ejendal
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Monica Soto-Velasquez
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Michael P Hayes
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Nicholas Santoro
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Martha J Larsen
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| | - Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology (Z.D., K.F.K.E., M.S.-V., M.P.H., V.J.W.), Purdue Institute for Drug Discovery (V.J.W.), and Purdue Institute for Integrative Neuroscience (V.J.W.), Purdue University, West Lafayette, Indiana; and Center for Chemical Genomics, University of Michigan, Ann Arbor, Michigan (N.S., M.J.L.)
| |
Collapse
|
4
|
Prolonged Morphine Treatment Alters Expression and Plasma Membrane Distribution of β-Adrenergic Receptors and Some Other Components of Their Signaling System in Rat Cerebral Cortex. J Mol Neurosci 2017; 63:364-376. [PMID: 29081032 DOI: 10.1007/s12031-017-0987-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 10/05/2017] [Indexed: 01/15/2023]
Abstract
β-Adrenergic signaling plays an important role in regulating diverse brain functions and alterations in this signaling have been observed in different neuropathological conditions. In this study, we investigated the effect of a 10-day treatment with high doses of morphine (10 mg/kg per day) on major components and functional state of the β-adrenergic receptor (β-AR) signaling system in the rat cerebral cortex. β-ARs were characterized by radioligand binding assays and amounts of various G protein subunits, adenylyl cyclase (AC) isoforms, G protein-coupled receptor kinases (GRKs), and β-arrestin were examined by Western blot analysis. AC activity was determined as a measure of functionality of the signaling system. We also assessed the partitioning of selected signaling proteins between the lipid raft and non-raft fractions prepared from cerebrocortical plasma membranes. Morphine treatment resulted in a significant upregulation of β-ARs, GRK3, and some AC isoforms (AC-I, -II, and -III). There was no change in quantity of G proteins and some other signaling molecules (AC-IV, AC-V/VI, GRK2, GRK5, GRK6, and β-arrestin) compared with controls. Interestingly, morphine exposure caused a partial redistribution of β-ARs, Gsα, Goα, and GRK2 between lipid rafts and bulk plasma membranes. Spatial localization of other signaling molecules within the plasma membrane was not changed. Basal as well as fluoride- and forskolin-stimulated AC activities were not significantly different in membrane preparations from control and morphine-treated animals. However, AC activity stimulated by the beta-AR agonist isoprenaline was markedly increased. This is the first study to demonstrate lipid raft association of key components of the cortical β-AR system and its sensitivity to morphine.
Collapse
|
5
|
Brust TF, Conley JM, Watts VJ. Gα(i/o)-coupled receptor-mediated sensitization of adenylyl cyclase: 40 years later. Eur J Pharmacol 2015; 763:223-32. [PMID: 25981304 DOI: 10.1016/j.ejphar.2015.05.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/02/2015] [Accepted: 05/11/2015] [Indexed: 12/20/2022]
Abstract
Heterologous sensitization of adenylyl cyclase (also referred to as superactivation, sensitization, or supersensitization of adenylyl cyclase) is a cellular adaptive response first described 40 years ago in the laboratory of Dr. Marshall Nirenberg. This apparently paradoxical cellular response occurs following persistent activation of Gαi/o-coupled receptors and causes marked enhancement in the activity of adenylyl cyclases, thereby increasing cAMP production. Since our last review in 2005, significant progress in the field has led to a better understanding of the relevance of, and the cellular biochemical processes that occur during the development and expression of heterologous sensitization. In this review we will discuss the recent advancements in the field and the mechanistic hypotheses on heterologous sensitization.
Collapse
Affiliation(s)
- Tarsis F Brust
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Jason M Conley
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA.
| |
Collapse
|
6
|
Skrabalova J, Drastichova Z, Novotny J. Morphine as a Potential Oxidative Stress-Causing Agent. MINI-REV ORG CHEM 2013; 10:367-372. [PMID: 24376392 PMCID: PMC3871421 DOI: 10.2174/1570193x113106660031] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 05/03/2013] [Accepted: 05/03/2013] [Indexed: 12/21/2022]
Abstract
Morphine exhibits important pharmacological effects for which it has been used in medical practice for quite a long time. However, it has a high addictive potential and can be abused. Long-term use of this drug can be connected with some pathological consequences including neurotoxicity and neuronal dysfunction, hepatotoxicity, kidney dysfunction, oxidative stress and apoptosis. Therefore, most studies examining the impact of morphine have been aimed at determining the effects induced by chronic morphine exposure in the brain, liver, cardiovascular system and macrophages. It appears that different tissues may respond to morphine diversely and are distinctly susceptible to oxidative stress and subsequent oxidative damage of biomolecules. Importantly, production of reactive oxygen/nitrogen species induced by morphine, which have been observed under different experimental conditions, can contribute to some pathological processes, degenerative diseases and organ dysfunctions occurring in morphine abusers or morphine-treated patients. This review attempts to provide insights into the possible relationship between morphine actions and oxidative stress.
Collapse
Affiliation(s)
- Jitka Skrabalova
- Department of Physiology, Faculty of Science, Charles University in Prague, Czech Republic
| | - Zdenka Drastichova
- Department of Physiology, Faculty of Science, Charles University in Prague, Czech Republic
| | - Jiri Novotny
- Department of Physiology, Faculty of Science, Charles University in Prague, Czech Republic
| |
Collapse
|
7
|
Ujcikova H, Dlouha K, Roubalova L, Vosahlikova M, Kagan D, Svoboda P. Up-regulation of adenylylcyclases I and II induced by long-term adaptation of rats to morphine fades away 20days after morphine withdrawal. Biochim Biophys Acta Gen Subj 2011; 1810:1220-9. [DOI: 10.1016/j.bbagen.2011.09.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Revised: 09/12/2011] [Accepted: 09/27/2011] [Indexed: 02/04/2023]
|
8
|
Valdizán EM, Díaz A, Pilar-Cuéllar F, Lantero A, Mostany R, Villar AV, Laorden ML, Hurlé MA. Chronic treatment with the opioid antagonist naltrexone favours the coupling of spinal cord μ-opioid receptors to Gαz protein subunits. Neuropharmacology 2011; 62:757-64. [PMID: 21903117 DOI: 10.1016/j.neuropharm.2011.08.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 08/03/2011] [Accepted: 08/19/2011] [Indexed: 11/30/2022]
Abstract
Sustained administration of opioid antagonists to rodents results in an enhanced antinociceptive response to agonists. We investigated the changes in spinal μ-opioid receptor signalling underlying this phenomenon. Rats received naltrexone (120 μg/h; 7 days) via osmotic minipumps. The antinociceptive response to the μ-agonist sufentanil was tested 24 h after naltrexone withdrawal. In spinal cord samples, we determined the interaction of μ-receptors with Gα proteins (agonist-stimulated [(35)S]GTPγS binding and immunoprecipitation of [(35)S]GTPγS-labelled Gα subunits) as well as μ-opioid receptor-dependent inhibition of the adenylyl cyclase (AC) activity. Chronic naltrexone treatment augmented DAMGO-stimulated [(35)S]GTPγS binding, potentiated the inhibitory effect of DAMGO on the AC/cAMP pathway, and increased the inverse agonist effect of naltrexone on cAMP accumulation. In control rats, the inhibitory effect of DAMGO on cAMP production was antagonized by pertussis toxin (PTX) whereas, after chronic naltrexone, the effect became resistant to the toxin, suggesting a coupling of μ-receptors to PTX-insensitive Gα(z) subunits. Immunoprecipitation assays confirmed the transduction switch from Gα(i/o) to Gα(z) proteins. The consequence was an enhancement of the antinociceptive response to sufentanil that, in consonance with the neurochemical data, was prevented by Gα(z)-antisense oligodeoxyribonucleotides but not by PTX. Such changes in opioid receptor signalling can be a double-edged sword. On the one hand, they may have potential applicability to the optimisation of the analgesic effects of opioid drugs for the control of pain. On the other hand, they represent an important homeostatic dysregulation of the endogenous opioid system that might account for undesirable effects in patients chronically treated with opioid antagonists. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
Collapse
Affiliation(s)
- Elsa M Valdizán
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Cantabria, Spain
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Brain-specific Gαz interacts with Src tyrosine kinase to regulate Mu-opioid receptor-NMDAR signaling pathway. Cell Signal 2009; 21:1444-54. [DOI: 10.1016/j.cellsig.2009.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/06/2009] [Accepted: 05/06/2009] [Indexed: 11/20/2022]
|
10
|
Clark MJ, Traynor JR. Mediation of adenylyl cyclase sensitization by PTX-insensitive GalphaoA, Galphai1, Galphai2 or Galphai3. J Neurochem 2007; 99:1494-504. [PMID: 17230639 DOI: 10.1111/j.1471-4159.2006.04176.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Chronic activation of mu-opioid receptors, which couple to pertussis toxin-sensitive Galphai/o proteins to inhibit adenylyl cyclase (AC), leads to a compensatory sensitization of AC. Pertussis toxin-insensitive mutations of Galphai/o subtypes, in which the pertussis toxin-sensitive cysteine is mutated to isoleucine (Galpha ), were used to determine whether each of the Galphai/o subtypes is able to mediate sensitization of AC. Galpha , G , G or G were individually transiently transfected into C6 glioma cells stably expressing the mu-opioid receptor, or transiently co-expressed with the mu-opioid receptor into human embryonic kidney (HEK)293T cells. Cells were treated with pertussis toxin to uncouple endogenous Galphai/o proteins, followed by acute or chronic treatment with the mu-opioid agonist, [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAMGO). Each Galphai/o subtype mediated acute DAMGO inhibition of AC and DAMGO-induced sensitization of AC. The potency for DAMGO to stimulate sensitization was independent of the Galphai/o subtype, but the level of sensitization was increased in clones expressing higher levels of Galphai/o subunits. Sensitization of AC mediated by a component of fetal bovine serum, which was also dependent on the level of functional Galphai/o subunits in the cell, was observed. This serum-mediated sensitization partially masked mu-opioid-mediated sensitization when expressed as percentage overshoot due to an apparent increase in AC activity.
Collapse
Affiliation(s)
- Mary J Clark
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan USA
| | | |
Collapse
|
11
|
Zhang L, Tetrault J, Wang W, Loh HH, Law PY. Short- and long-term regulation of adenylyl cyclase activity by delta-opioid receptor are mediated by Galphai2 in neuroblastoma N2A cells. Mol Pharmacol 2006; 69:1810-9. [PMID: 16525132 DOI: 10.1124/mol.105.021352] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of the opioid receptor results in short-term inhibition of intracellular cAMP levels followed by receptor desensitization and subsequent increase of cAMP above the control level (adenylyl cyclase superactivation). Using adenovirus to deliver pertussis toxin-insensitive mutants of the alpha-subunits of G(i/o) that are expressed in neuroblastoma Neuro2A cells (Galpha(i2), Galpha(i3), and Galpha(o)), we examined the identities of the G proteins involved in the short- and long-term action of the delta-opioid receptor (DOR). Pertussis toxin pretreatment completely abolished the ability of [d-Pen(2), d-Pen(5)]-enkephalin (DPDPE) to inhibit forskolin-stimulated intracellular cAMP production. Expression of the C352L mutant of Galpha(i2), and not the C351L mutants of Galpha(i3) or Galpha(o), rescued the short-term effect of DPDPE after pertussis toxin treatment. The ability of Galpha(i2) in mediating DOR inhibition of adenylyl cyclase activity was also reflected in the ability of Galpha(i2), not Galpha(i3) or Galpha(o), to coimmunoprecipitate with DOR. Coincidently, after long-term DPDPE treatment, pertussis toxin treatment eliminated the antagonist naloxone-induced superactivation of adenylyl cyclase activity. Again, only the C352L mutant of Galpha(i2) restored the adenylyl cyclase superactivation after pertussis toxin treatment. More importantly, the C352L mutant of Galpha(i2) remained associated with DOR after long-term agonist and pertussis toxin treatment whereas the wild-type Galpha(i2) did not. These data suggest that Galpha(i2) serves as the signaling molecule in both DOR-mediated short- and long-term regulation of adenylyl cyclase activity.
Collapse
MESH Headings
- Adenoviridae/genetics
- Adenylyl Cyclase Inhibitors
- Adenylyl Cyclases/metabolism
- Animals
- Cyclic AMP/metabolism
- Enkephalin, D-Penicillamine (2,5)-/antagonists & inhibitors
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- GTP-Binding Protein alpha Subunit, Gi2/antagonists & inhibitors
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- Immunoprecipitation
- Mice
- Naloxone/pharmacology
- Neuroblastoma
- Pertussis Toxin/pharmacology
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/metabolism
- Tumor Cells, Cultured
Collapse
Affiliation(s)
- Lei Zhang
- Department of Pharmacology, Medical School, University of Minnesota, 6-120 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA.
| | | | | | | | | |
Collapse
|
12
|
King T, Ossipov MH, Vanderah TW, Porreca F, Lai J. Is paradoxical pain induced by sustained opioid exposure an underlying mechanism of opioid antinociceptive tolerance? Neurosignals 2006; 14:194-205. [PMID: 16215302 DOI: 10.1159/000087658] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Indexed: 12/29/2022] Open
Abstract
Opiates are the primary treatment for pain management in cancer patients reporting moderate to severe pain, and are being increasingly used for non-cancer chronic pain. However, prolonged administration of opiates is associated with significant problems including the development of antinociceptive tolerance, wherein higher doses of the drug are required over time to elicit the same amount of analgesia. High doses of opiates result in serious side effects such as constipation, nausea, vomiting, dizziness, somnolence, and impairment of mental alertness. In addition, sustained exposure to morphine has been shown to result in paradoxical pain in regions unaffected by the initial pain complaint, and which may also result in dose escalation, i.e. 'analgesic tolerance'. A concept that has been gaining considerable experimental validation is that prolonged use of opioids elicits paradoxical, abnormal pain. This enhanced pain state requires additional opioids to maintain a constant level of antinociception, and consequently may be interpreted as antinociceptive tolerance. Many substances have been shown to block or reverse antinociceptive tolerance. A non-inclusive list of examples of substances reported to block or reverse opioid antinociceptive tolerance include: substance P receptor (NK-1) antagonists, calcitonin gene-related peptide (CGRP) receptor antagonists, nitric oxide (NO) synthase inhibitors, calcium channel blockers, cyclooxygenase (COX) inhibitors, protein kinase C inhibitors, competitive and non-competitive antagonists of the NMDA (N-methyl-D-aspartate) receptor, AMPA (alpha-amino-3-hydroxy-5-methyl-4 isoxazolepropionic acid) antagonists, anti-dynorphin antiserum, and cholecystokinin (CCK) receptor antagonists. Without exception, these substances are also antagonists of pain-enhancing agents. Prolonged opiate administration indeed induces upregulation of substance P (SP) and calcitonin gene-related peptide (CGRP) within sensory fibers in vivo, and this is accompanied by an enhanced release of excitatory neurotransmitters and neuropeptides from primary afferent fibers upon stimulation. The enhanced evoked release of neuropeptides is correlated with the onset of abnormal pain states and opioid antinociceptive tolerance. Importantly, the descending pain modulatory pathway from the brainstem rostral ventromedial medulla (RVM) via the dorsolateral funiculus (DLF) is critical for maintaining the changes observed in the spinal cord, abnormal pain states and antinociceptive tolerance, because animals with lesion of the DLF did not show enhanced evoked neuropeptide release, or develop abnormal pain or antinociceptive tolerance upon sustained exposure to opiates. Microinjection of either lidocaine or a CCK antagonist into the RVM blocked both thermal and touch hypersensitivity as well as antinociceptive tolerance. Thus, prolonged opioid exposure enhances a descending pain facilitatory pathway from the RVM that is mediated at least in part by CCK activity and is essential for the maintenance of antinociceptive tolerance.
Collapse
Affiliation(s)
- Tamara King
- Department of Pharmacology, University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
| | | | | | | | | |
Collapse
|
13
|
Small-Howard A, Shimoda L, Adra C, Turner H. Anti-inflammatory potential of CB1-mediated cAMP elevation in mast cells. Biochem J 2005; 388:465-73. [PMID: 15669919 PMCID: PMC1138953 DOI: 10.1042/bj20041682] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cannabinoids are broadly immunosuppressive, and anti-inflammatory properties have been reported for certain marijuana constituents and endogenously produced cannabinoids. The CB2 cannabinoid receptor is an established constituent of immune system cells, and we have recently established that the CB1 cannabinoid receptor is expressed in mast cells. In the present study, we sought to define a role for CB1 in mast cells and to identify the signalling pathways that may mediate the suppressive effects of CB1 ligation on mast cell activation. Our results show that CB1 and CB2 mediate diametrically opposed effects on cAMP levels in mast cells. The observed long-term stimulation of cAMP levels by the Galpha(i/o)-coupled CB1 is paradoxical, and our results indicate that it may be attributed to CB1-mediated transcriptional regulation of specific adenylate cyclase isoenzymes that exhibit superactivatable kinetics. Taken together, these results reveal the complexity in signalling of natively co-expressed cannabinoid receptors and suggest that some anti-inflammatory effects of CB1 ligands may be attributable to sustained cAMP elevation that, in turn, causes suppression of mast cell degranulation.
Collapse
MESH Headings
- Adenylyl Cyclases/metabolism
- Animals
- Arachidonic Acids/pharmacology
- Camphanes/pharmacology
- Cell Line
- Colforsin/pharmacology
- Cyclic AMP/biosynthesis
- Cytosol/drug effects
- Cytosol/metabolism
- Down-Regulation
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Humans
- Indoles/pharmacology
- Ligands
- Mast Cells/drug effects
- Mast Cells/metabolism
- Morpholines/pharmacology
- Pertussis Toxin/pharmacology
- Pyrazoles/pharmacology
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/physiology
- Receptor, Cannabinoid, CB2/agonists
- Receptor, Cannabinoid, CB2/physiology
- Signal Transduction
- Time Factors
- Transcription, Genetic
- Up-Regulation
Collapse
Affiliation(s)
- Andrea L. Small-Howard
- *Laboratory of Cell Biology and Immunology, Center for Biomedical Research at the Queen's Medical Center, Honolulu, HI 96813, U.S.A
| | - Lori M. N. Shimoda
- *Laboratory of Cell Biology and Immunology, Center for Biomedical Research at the Queen's Medical Center, Honolulu, HI 96813, U.S.A
| | - Chaker N. Adra
- †Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, U.S.A
| | - Helen Turner
- *Laboratory of Cell Biology and Immunology, Center for Biomedical Research at the Queen's Medical Center, Honolulu, HI 96813, U.S.A
- ‡Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96822, U.S.A
- To whom correspondence should be addressed, at Queen's Center for Biomedical Research, 1301 Punchbowl Street, University Tower 811, Honolulu, HI 96813, U.S.A. (email )
| |
Collapse
|
14
|
Mazarakou G, Georgoussi Z. STAT5A interacts with and is phosphorylated upon activation of the mu-opioid receptor. J Neurochem 2005; 93:918-31. [PMID: 15857395 DOI: 10.1111/j.1471-4159.2005.03069.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Signal Transducers and Activators of Transcription (STATs) are transcription factors shown to be activated by G protein-coupled receptors. In the present study, we demonstrate that acute morphine or [D-Ala(2),N-Me-Phe(4),Gly(5)-ol]enkephalin (DAMGO) exposure of COS-7 cells transiently transfected with the micro-opioid receptor and STAT5A, leads to receptor-dependent tyrosine phosphorylation of STAT5A. Activation of HEK293 cells, stably expressing the micro-opioid receptor with micro-opioid agonists results in the transcriptional activation of a STAT-responsive reporter gene. Pertussis toxin has no effect on the level of STAT5A phosphorylation, while the Src inhibitor PP1 abolishes opioid-dependent STAT5A phosphorylation. All three opioid receptor subtypes -micro, delta and kappa- share the conserved motif YXXL (amino-acids 336-339 for the micro-opioid receptor), known to be critical for STAT5A/5B binding. Co-immunoprecipitation and pull-down experiments using a GST-carboxyl-terminal tail of the micro-opioid receptor and rat brain, or COS-7 cell cytosolic extracts, demonstrate the direct binding of STAT5A to this region. Mutation of the Y336 to alanine does not prevent STAT5A binding, whereas deletion of the entire putative STAT5A binding site YXXL abolishes STAT5A interaction to the carboxyl-terminal tail of the micro-opioid receptor. Collectively, our results demonstrate the association of STAT5A with the micro-opioid receptor and reveal novel signalling pathways in the regulation of transcription by the micro-opioid receptor.
Collapse
Affiliation(s)
- Georgia Mazarakou
- Laboratory of Cellular Signalling and Molecular Pharmacology, Institute of Biology, National Center for Scientific Research Demokritos, Athens, Greece
| | | |
Collapse
|
15
|
Steiner D, Saya D, Schallmach E, Simonds WF, Vogel Z. Adenylyl cyclase type-VIII activity is regulated by G(betagamma) subunits. Cell Signal 2005; 18:62-8. [PMID: 15925485 DOI: 10.1016/j.cellsig.2005.03.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2005] [Accepted: 03/15/2005] [Indexed: 10/25/2022]
Abstract
The Ca2+-activated adenylyl cyclase type VIII (AC-VIII) has been implicated in several forms of neural plasticity, including drug addiction and learning and memory. It has not been clear whether Gi/o proteins and G-protein coupled receptors regulate the activity of AC-VIII. Here we show in intact mammalian cell system that AC-VIII is inhibited by mu-opioid receptor activation and that this inhibition is pertussis toxin sensitive. Moreover, we show that G(betagamma) subunits inhibit AC-VIII activity, while constitutively active alphai/o subunits do not. Different Gbeta isoforms varied in their efficacies, with Gbeta1gamma2 or Gbeta2gamma2 being more efficient than Gbeta3gamma2 and Gbeta4gamma2, while Gbeta5 (transfected with gamma2) had no effect. As for the Ggamma subunits, Gbeta1 inhibited AC-VIII activity in the presence of all gamma subunits tested except for gamma5 that had only a marginal activity. Moreover, cotransfection with proteins known to serve as scavengers of Gbetagamma dimers, or to reduce Gbetagamma plasma membrane anchorage, markedly attenuated the mu-opioid receptor-induced inhibition of AC-VIII. These results demonstrate that Gbetagamma (originating from agonist activation of these receptors) and probably not Galphai/o subunits are involved in the agonist inhibition of AC-VIII.
Collapse
Affiliation(s)
- Debora Steiner
- Department of Neurobiology, The Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | | | | |
Collapse
|
16
|
Watts VJ, Neve KA. Sensitization of adenylate cyclase by Galpha i/o-coupled receptors. Pharmacol Ther 2005; 106:405-21. [PMID: 15922020 DOI: 10.1016/j.pharmthera.2004.12.005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/21/2004] [Indexed: 11/23/2022]
Abstract
Activation of receptors coupled to inhibitory G proteins (Galpha i/o) has opposing consequences for cyclic AMP accumulation and the activity of cyclic AMP-dependent protein kinase, depending on the duration of stimulation. Acute activation inhibits the activity of adenylate cyclase, thereby attenuating cyclic AMP accumulation; in contrast, persistent activation of Galpha i/o-coupled receptors produces a paradoxical enhancement of adenylate cyclase activity, thus increasing cyclic AMP accumulation when the action of the inhibitory receptor is terminated. This heterologous sensitization of cyclic AMP signaling, also called superactivation or supersensitization, likely represents a cellular adaptive response, a mechanism by which the cell compensates for chronic inhibitory input. Recent advances in our knowledge of G protein-mediated signaling, regulation of adenylate cyclase, and other cellular signaling mechanisms have extensively increased our insight into the mechanisms and significance of this phenomenon. In particular, recent evidence points to the Galpha(s)-adenylate cyclase interface as a locus for the expression of the sensitized adenylate cyclase response, and to isoform-specific phosphorylation of adenylate cyclase as one mechanism that can produce sensitization. Galpha i/o-coupled receptor-induced heterologous sensitization may contribute to enhanced Galpha(s)-coupled receptor signaling following neurotransmitter elevations induced by the administration of drugs of abuse and during other types of neuronal function or dysfunction. This review will focus on recent advances in our understanding of signaling pathways that are involved in sensitization and describe the potential role of sensitization in neuronal function.
Collapse
Affiliation(s)
- Val J Watts
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
| | | |
Collapse
|
17
|
Clark MJ, Neubig RR, Traynor JR. Endogenous regulator of G protein signaling proteins suppress Galphao-dependent, mu-opioid agonist-mediated adenylyl cyclase supersensitization. J Pharmacol Exp Ther 2004; 310:215-22. [PMID: 15014136 DOI: 10.1124/jpet.103.064824] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chronic mu-opioid agonist treatment leads to dependence with withdrawal on removal of agonist. At the cellular level withdrawal is accompanied by a supersensitization of adenylyl cyclase, an effect that requires inhibitory Galpha proteins. Inhibitory Galpha protein action is modulated by regulator of G protein signaling (RGS) proteins that act as GTPase activating proteins and reduce the lifetime of Galpha-GTP. In this article, we use C6 glioma cells expressing the rat mu-opioid receptor (C6mu) to examine the hypothesis that Galphao alone can mediate mu-opioid agonist induced adenylyl cyclase supersensitivity and that endogenous RGS proteins serve to limit the extent of this supersensitization. C6mu cells were stably transfected with pertussis toxin (PTX)-insensitive Galphao that was either sensitive or insensitive to endogenous RGS proteins. Cells were treated with PTX to uncouple endogenous Galpha proteins followed by exposure to the mu-opioid agonists [D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin or morphine. Supersensitization was observed in cells expressing wild-type Galpha, but this was lost on PTX treatment. In cells expressing PTX-insensitive Galphao supersensitization was recovered, confirming that Galphao alone can support supersensitization. In cells expressing the RGS-insensitive mutant Galphao, there was a greater degree of supersensitization and the concentration of micro-agonist needed to achieve half-maximal supersensitization was reduced by 10-fold. The amount of supersensitization seen did not directly relate to the degree of acute inhibition of adenylyl cyclase. These results demonstrate a role for Galphao in adenylyl cyclase supersensitization after mu-agonist exposure and show that this action is modulated by endogenous RGS proteins.
Collapse
Affiliation(s)
- Mary J Clark
- Department of Pharmacology, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0632, USA
| | | | | |
Collapse
|
18
|
Alonzo NC, Bayer BM. Antagonism of N-methyl-D-aspartate receptors reduces the vulnerability of the immune system to stress after chronic morphine. J Pharmacol Exp Ther 2003; 307:793-800. [PMID: 12966157 DOI: 10.1124/jpet.103.053264] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been shown that morphine-tolerant animals have an altered immunological sensitivity to stress. Although the glutamatergic system has been implicated in the neuroadaptive process underlying this tolerant state, its potential role in development of the altered immunological sensitivity consequent to chronic morphine treatment is not known. To determine this, a morphine-tolerant state was induced by 10-day administration of an escalating dose of morphine from 10 to 40 mg/kg (s.c., b.i.d.), and lymphocyte proliferative response to a T-cell mitogen was measured. Morphine challenge (10 mg/kg s.c.) after days of treatment was gradually less immunosuppressive, and this tolerance progression was delayed by concurrent administration of the N-methyl-D-aspartate (NMDA) receptor antagonist (-)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) (0.1 mg/kg s.c.) with chronic morphine. The effect was independent of glucocorticoid level changes and was not a result of an acute interaction of the drugs or the prolonged presence of the antagonist alone. Subsequent to chronic treatment, animals were subjected to opioid withdrawal and water stress. Both stressors induced 50% immunosuppression in morphine-tolerant animals compared with saline-treated controls. Increased immunological sensitivity to these stressors was attenuated when MK-801 was administered with chronic morphine as demonstrated by an accelerated recovery rate and lack of immunosuppression from opioid withdrawal and water stress, respectively. Together, these findings provide the first evidence that the neuroadapted state of the immune response after chronic morphine can be modified by NMDA receptor antagonism, as illustrated by a temporal deceleration of the development of immunological tolerance during chronic treatment that is associated with an attenuation of the immunological vulnerability of morphine-tolerant animals to stress.
Collapse
Affiliation(s)
- Norma C Alonzo
- Department of Neuroscience, Georgetown University, 3970 Reservoir Road NW, Box 54624, NRB EG12, Washington, DC 20057-54624, USA
| | | |
Collapse
|
19
|
Tu Y, Nayak SK, Woodson J, Ross EM. Phosphorylation-regulated inhibition of the Gz GTPase-activating protein activity of RGS proteins by synapsin I. J Biol Chem 2003; 278:52273-81. [PMID: 14557263 DOI: 10.1074/jbc.m309626200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synapsins are neuronal proteins that bind and cluster synaptic vesicles in the presynaptic space, presumably by anchoring to actin filaments, but specific regulatory functions of the synapsins are unknown. We found that a sub-population of brain synapsin Ia, a splice variant of one of three synapsin isoforms, inhibits the GTPase-activating protein (GAP) activity of several RGS proteins. Inhibition is highly selective for Galphaz, a member of the Gi family that is found in neurons, platelets, adrenal chromaffin cells, and a few other neurosecretory cells. Gz has been indirectly implicated in the regulation of secretion. Synapsin Ia constitutes a major fraction of the total GAP-inhibitory activity in brain, and its inhibitory activity is absent from the brains of synapsin I(-/-)/II(-/-) mice. Inhibition depends on the cationic D/E domain of synapsin. Phosphorylation of synapsin Ia at serine 9 by either cyclic AMP-dependent protein kinase or p21-activated protein kinase (PAK1) attenuates its potency as a GAP inhibitor more than 7-fold. Synapsin can thus act as a phosphorylation-modulated mediator of feedback regulation of Gz signaling by the synaptic machinery.
Collapse
Affiliation(s)
- Yaping Tu
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
| | | | | | | |
Collapse
|
20
|
Abstract
This paper is the twenty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over a quarter-century of research. It summarizes papers published during 2002 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).
Collapse
Affiliation(s)
- Richard J Bodnar
- Department of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, CUNY, 65-30 Kissena Blvd., Flushing, NY 11367, USA.
| | | |
Collapse
|