1
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Hovah ME, Holzgrabe U. Bivalent and bitopic ligands of the opioid receptors: The prospects of a dual approach. Med Res Rev 2024; 44:2545-2599. [PMID: 38751227 DOI: 10.1002/med.22050] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 04/09/2024] [Accepted: 05/05/2024] [Indexed: 10/05/2024]
Abstract
Opioid receptors belonging to the class A G-protein coupled receptors (GPCRs) are the targets of choice in the treatment of acute and chronic pain. However, their on-target side effects such as respiratory depression, tolerance and addiction have led to the advent of the 'opioid crisis'. In the search for safer analgesics, bivalent and more recently, bitopic ligands have emerged as valuable tool compounds to probe these receptors. The activity of bivalent and bitopic ligands rely greatly on the allosteric nature of the GPCRs. Bivalent ligands consist of two pharmacophores, each binding to the individual orthosteric binding site (OBS) of the monomers within a dimer. Bitopic or dualsteric ligands bridge the gap between the OBS and the spatially distinct, less conserved allosteric binding site (ABS) through the simultaneous occupation of these two sites. Bivalent and bitopic ligands stabilize distinct conformations of the receptors which ultimately translates into unique signalling and pharmacological profiles. Some of the interesting properties shown by these ligands include improved affinity and/or efficacy, subtype and/or functional selectivity and reduced side effects. This review aims at providing an overview of some of the bivalent and bitopic ligands of the opioid receptors and, their pharmacology in the hope of inspiring the design and discovery of the next generation of opioid analgesics.
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Affiliation(s)
- Marie Emilie Hovah
- Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Wuerzburg, Germany
| | - Ulrike Holzgrabe
- Institute of Pharmacy and Food Chemistry, University of Wuerzburg, Am Hubland, Wuerzburg, Germany
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2
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Shen S, Wu C, Lin G, Yang X, Zhou Y, Zhao C, Miao Z, Tian X, Wang K, Yang Z, Liu Z, Guo N, Li Y, Xia A, Zhou P, Liu J, Yan W, Ke B, Yang S, Shao Z. Structure-based identification of a G protein-biased allosteric modulator of cannabinoid receptor CB1. Proc Natl Acad Sci U S A 2024; 121:e2321532121. [PMID: 38830102 PMCID: PMC11181136 DOI: 10.1073/pnas.2321532121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 04/01/2024] [Indexed: 06/05/2024] Open
Abstract
Cannabis sativa is known for its therapeutic benefit in various diseases including pain relief by targeting cannabinoid receptors. The primary component of cannabis, Δ9-tetrahydrocannabinol (THC), and other agonists engage the orthosteric site of CB1, activating both Gi and β-arrestin signaling pathways. The activation of diverse pathways could result in on-target side effects and cannabis addiction, which may hinder therapeutic potential. A significant challenge in pharmacology is the design of a ligand that can modulate specific signaling of CB1. By leveraging insights from the structure-function selectivity relationship (SFSR), we have identified Gi signaling-biased agonist-allosteric modulators (ago-BAMs). Further, two cryoelectron microscopy (cryo-EM) structures reveal the binding mode of ago-BAM at the extrahelical allosteric site of CB1. Combining mutagenesis and pharmacological studies, we elucidated the detailed mechanism of ago-BAM-mediated biased signaling. Notably, ago-BAM CB-05 demonstrated analgesic efficacy with fewer side effects, minimal drug toxicity and no cannabis addiction in mouse pain models. In summary, our finding not only suggests that ago-BAMs of CB1 provide a potential nonopioid strategy for pain management but also sheds light on BAM identification for GPCRs.
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Affiliation(s)
- Siyuan Shen
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
- Frontiers Medical Center, Tianfu Jincheng Laboratory, Chengdu610212, Sichuan, China
| | - Chao Wu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Guifeng Lin
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Xin Yang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Yangli Zhou
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Chang Zhao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Zhuang Miao
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Centre of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Xiaowen Tian
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Kexin Wang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Zhiqian Yang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Zhiyu Liu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Nihong Guo
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Yueshan Li
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Anjie Xia
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Pei Zhou
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Jingming Liu
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Wei Yan
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Bowen Ke
- Department of Anesthesiology, Laboratory of Anesthesia and Critical Care Medicine, National-Local Joint Engineering Research Centre of Translational Medicine of Anesthesiology, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
| | - Shengyong Yang
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
- Frontiers Medical Center, Tianfu Jincheng Laboratory, Chengdu610212, Sichuan, China
| | - Zhenhua Shao
- Division of Nephrology and Kidney Research Institute, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu610041, Sichuan, China
- Frontiers Medical Center, Tianfu Jincheng Laboratory, Chengdu610212, Sichuan, China
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3
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Che T, Roth BL. Molecular basis of opioid receptor signaling. Cell 2023; 186:5203-5219. [PMID: 37995655 PMCID: PMC10710086 DOI: 10.1016/j.cell.2023.10.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/13/2023] [Accepted: 10/27/2023] [Indexed: 11/25/2023]
Abstract
Opioids are used for pain management despite the side effects that contribute to the opioid crisis. The pursuit of non-addictive opioid analgesics remains unattained due to the unresolved intricacies of opioid actions, receptor signaling cascades, and neuronal plasticity. Advancements in structural, molecular, and computational tools illuminate the dynamic interplay between opioids and opioid receptors, as well as the molecular determinants of signaling pathways, which are potentially interlinked with pharmacological responses. Here, we review the molecular basis of opioid receptor signaling with a focus on the structures of opioid receptors bound to endogenous peptides or pharmacological agents. These insights unveil specific interactions that dictate ligand selectivity and likely their distinctive pharmacological profiles. Biochemical analysis further unveils molecular features governing opioid receptor signaling. Simultaneously, the synergy between computational biology and medicinal chemistry continues to expedite the discovery of novel chemotypes with the promise of yielding more efficacious and safer opioid compounds.
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Affiliation(s)
- Tao Che
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA; Center for Clinical Pharmacology, University of Health Sciences & Pharmacy and Washington University School of Medicine, Saint Louis, MO 63110, USA.
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina Chapel Hill School of Medicine, Chapel Hill 27599, NC, USA.
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4
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Ramos-Gonzalez N, Paul B, Majumdar S. IUPHAR themed review: Opioid efficacy, bias, and selectivity. Pharmacol Res 2023; 197:106961. [PMID: 37844653 DOI: 10.1016/j.phrs.2023.106961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/18/2023]
Abstract
Drugs acting at the opioid receptor family are clinically used to treat chronic and acute pain, though they represent the second line of treatment behind GABA analogs, antidepressants and SSRI's. Within the opioid family mu and kappa opioid receptor are commonly targeted. However, activation of the mu opioid receptor has side effects of constipation, tolerance, dependence, euphoria, and respiratory depression; activation of the kappa opioid receptor leads to dysphoria and sedation. The side effects of mu opioid receptor activation have led to mu receptor drugs being widely abused with great overdose risk. For these reasons, newer safer opioid analgesics are in high demand. For many years a focus within the opioid field was finding drugs that activated the G protein pathway at mu opioid receptor, without activating the β-arrestin pathway, known as biased agonism. Recent advances have shown that this may not be the way forward to develop safer analgesics at mu opioid receptor, though there is still some promise at the kappa opioid receptor. Here we discuss recent novel approaches to develop safer opioid drugs including efficacy vs bias and fine-tuning receptor activation by targeting sub-pockets in the orthosteric site, we explore recent works on the structural basis of bias, and we put forward the suggestion that Gα subtype selectivity may be an exciting new area of interest.
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Affiliation(s)
- Nokomis Ramos-Gonzalez
- Department of Anesthesiology and Washington University Pain Center, Washington University School of Medicine, Saint Louis, MO, USA; Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St. Louis and Washington University School of Medicine, St. Louis, MO, USA
| | - Barnali Paul
- Department of Anesthesiology and Washington University Pain Center, Washington University School of Medicine, Saint Louis, MO, USA; Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St. Louis and Washington University School of Medicine, St. Louis, MO, USA
| | - Susruta Majumdar
- Department of Anesthesiology and Washington University Pain Center, Washington University School of Medicine, Saint Louis, MO, USA; Center for Clinical Pharmacology, University of Health Sciences & Pharmacy at St. Louis and Washington University School of Medicine, St. Louis, MO, USA.
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5
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Ono Y, Kawakami K, Nakamura G, Ishida S, Aoki J, Inoue A. Generation of Gαi knock-out HEK293 cells illuminates Gαi-coupling diversity of GPCRs. Commun Biol 2023; 6:112. [PMID: 36709222 PMCID: PMC9884212 DOI: 10.1038/s42003-023-04465-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 01/11/2023] [Indexed: 01/29/2023] Open
Abstract
G-protein-coupled receptors (GPCRs) are pivotal cell membrane proteins that sense extracellular molecules and activate cellular responses. The G-protein α subunit i (Gαi) family represents the most common GPCR-coupling partner and consists of eight subunits with distinct signaling properties. However, analyzing the coupling pattern has been challenging owing to endogenous expression of the Gαi subunits in virtually all cell lines. Here, we generate a HEK293 cell line lacking all Gαi subunits, which enables the measurement of GPCR-Gαi coupling upon transient re-expression of a specific Gαi subunit. We profile Gαi-coupling selectivity across 11 GPCRs by measuring ligand-induced inhibitory activity for cAMP accumulation. The coupling profiles are then classified into three clusters, representing those preferentially coupled to Gαz, those to Gαo, and those with unapparent selectivity. These results indicate that individual Gαi-coupled GPCRs fine-tune Gαi signaling by exerting coupling preference at the Gαi-subunit level.
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Affiliation(s)
- Yuki Ono
- grid.69566.3a0000 0001 2248 6943Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
| | - Kouki Kawakami
- grid.69566.3a0000 0001 2248 6943Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
| | - Gaku Nakamura
- grid.69566.3a0000 0001 2248 6943Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
| | - Satoru Ishida
- grid.69566.3a0000 0001 2248 6943Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
| | - Junken Aoki
- grid.26999.3d0000 0001 2151 536XDepartment of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 Japan
| | - Asuka Inoue
- grid.69566.3a0000 0001 2248 6943Molecular and Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578 Japan
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6
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Faouzi A, Wang H, Zaidi SA, DiBerto JF, Che T, Qu Q, Robertson MJ, Madasu MK, El Daibani A, Varga BR, Zhang T, Ruiz C, Liu S, Xu J, Appourchaux K, Slocum ST, Eans SO, Cameron MD, Al-Hasani R, Pan YX, Roth BL, McLaughlin JP, Skiniotis G, Katritch V, Kobilka BK, Majumdar S. Structure-based design of bitopic ligands for the µ-opioid receptor. Nature 2023; 613:767-774. [PMID: 36450356 PMCID: PMC10328120 DOI: 10.1038/s41586-022-05588-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 11/22/2022] [Indexed: 12/05/2022]
Abstract
Mu-opioid receptor (µOR) agonists such as fentanyl have long been used for pain management, but are considered a major public health concern owing to their adverse side effects, including lethal overdose1. Here, in an effort to design safer therapeutic agents, we report an approach targeting a conserved sodium ion-binding site2 found in µOR3 and many other class A G-protein-coupled receptors with bitopic fentanyl derivatives that are functionalized via a linker with a positively charged guanidino group. Cryo-electron microscopy structures of the most potent bitopic ligands in complex with µOR highlight the key interactions between the guanidine of the ligands and the key Asp2.50 residue in the Na+ site. Two bitopics (C5 and C6 guano) maintain nanomolar potency and high efficacy at Gi subtypes and show strongly reduced arrestin recruitment-one (C6 guano) also shows the lowest Gz efficacy among the panel of µOR agonists, including partial and biased morphinan and fentanyl analogues. In mice, C6 guano displayed µOR-dependent antinociception with attenuated adverse effects, supporting the µOR sodium ion-binding site as a potential target for the design of safer analgesics. In general, our study suggests that bitopic ligands that engage the sodium ion-binding pocket in class A G-protein-coupled receptors can be designed to control their efficacy and functional selectivity profiles for Gi, Go and Gz subtypes and arrestins, thus modulating their in vivo pharmacology.
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MESH Headings
- Animals
- Mice
- Analgesics, Opioid/chemistry
- Analgesics, Opioid/metabolism
- Arrestins/metabolism
- Cryoelectron Microscopy
- Fentanyl/analogs & derivatives
- Fentanyl/chemistry
- Fentanyl/metabolism
- Ligands
- Morphinans/chemistry
- Morphinans/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/chemistry
- Receptors, Opioid, mu/metabolism
- Receptors, Opioid, mu/ultrastructure
- Binding Sites
- Nociception
- Drug Design
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Affiliation(s)
- Abdelfattah Faouzi
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Haoqing Wang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
| | - Saheem A Zaidi
- Department of Quantitative and Computational Biology, Department of Chemistry, Bridge Institute and Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, USA
| | - Jeffrey F DiBerto
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Tao Che
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Qianhui Qu
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Michael J Robertson
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Manish K Madasu
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Amal El Daibani
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Balazs R Varga
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Tiffany Zhang
- Department of Neurology and Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Claudia Ruiz
- Department of Chemistry, Scripps Research, Jupiter, FL, USA
| | - Shan Liu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Jin Xu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Kevin Appourchaux
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Samuel T Slocum
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Shainnel O Eans
- Department of Pharmacodynamics, University of Florida, Gainesville, FL, USA
| | | | - Ream Al-Hasani
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA
| | - Ying Xian Pan
- Department of Neurology and Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Jay P McLaughlin
- Department of Pharmacodynamics, University of Florida, Gainesville, FL, USA
| | - Georgios Skiniotis
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Vsevolod Katritch
- Department of Quantitative and Computational Biology, Department of Chemistry, Bridge Institute and Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, USA.
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, USA.
| | - Susruta Majumdar
- Center for Clinical Pharmacology, University of Health Sciences and Pharmacy and Washington University School of Medicine, St Louis, MO, USA.
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7
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Derouiche L, Massotte D. G protein-coupled receptor heteromers are key players in substance use disorder. Neurosci Biobehav Rev 2018; 106:73-90. [PMID: 30278192 DOI: 10.1016/j.neubiorev.2018.09.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 09/25/2018] [Accepted: 09/26/2018] [Indexed: 12/19/2022]
Abstract
G protein-coupled receptors (GPCR) represent the largest family of membrane proteins in the human genome. Physical association between two different GPCRs is linked to functional interactions which generates a novel entity, called heteromer, with specific ligand binding and signaling properties. Heteromerization is increasingly recognized to take place in the mesocorticolimbic pathway and to contribute to various aspects related to substance use disorder. This review focuses on heteromers identified in brain areas relevant to drug addiction. We report changes at the molecular and cellular levels that establish specific functional impact and highlight behavioral outcome in preclinical models. Finally, we briefly discuss selective targeting of native heteromers as an innovative therapeutic option.
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Affiliation(s)
- Lyes Derouiche
- Institut des Neurosciences Cellulaires et Integratives, UPR 3212, 5 rue Blaise Pascal, F-67000 Strasbourg, France
| | - Dominique Massotte
- Institut des Neurosciences Cellulaires et Integratives, UPR 3212, 5 rue Blaise Pascal, F-67000 Strasbourg, France.
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8
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Suppression of RGSz1 function optimizes the actions of opioid analgesics by mechanisms that involve the Wnt/β-catenin pathway. Proc Natl Acad Sci U S A 2018; 115:E2085-E2094. [PMID: 29440403 DOI: 10.1073/pnas.1707887115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Regulator of G protein signaling z1 (RGSz1), a member of the RGS family of proteins, is present in several networks expressing mu opioid receptors (MOPRs). By using genetic mouse models for global or brain region-targeted manipulations of RGSz1 expression, we demonstrated that the suppression of RGSz1 function increases the analgesic efficacy of MOPR agonists in male and female mice and delays the development of morphine tolerance while decreasing the sensitivity to rewarding and locomotor activating effects. Using biochemical assays and next-generation RNA sequencing, we identified a key role of RGSz1 in the periaqueductal gray (PAG) in morphine tolerance. Chronic morphine administration promotes RGSz1 activity in the PAG, which in turn modulates transcription mediated by the Wnt/β-catenin signaling pathway to promote analgesic tolerance to morphine. Conversely, the suppression of RGSz1 function stabilizes Axin2-Gαz complexes near the membrane and promotes β-catenin activation, thereby delaying the development of analgesic tolerance. These data show that the regulation of RGS complexes, particularly those involving RGSz1-Gαz, represents a promising target for optimizing the analgesic actions of opioids without increasing the risk of dependence or addiction.
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9
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Doyle GA, Schwebel CL, Ruiz SE, Chou AD, Lai AT, Wang MJ, Smith GG, Buono RJ, Berrettini WH, Ferraro TN. Analysis of candidate genes for morphine preference quantitative trait locus Mop2. Neuroscience 2014; 277:403-16. [PMID: 25058503 DOI: 10.1016/j.neuroscience.2014.07.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Revised: 07/14/2014] [Accepted: 07/14/2014] [Indexed: 11/26/2022]
Abstract
Compared to DBA/2J (D2), C57BL/6J (B6) inbred mice exhibit strong morphine preference when tested using a two-bottle choice drinking paradigm. A morphine preference quantitative trait locus (QTL), Mop2, was originally mapped to proximal chromosome (Chr) 10 using a B6xD2 F2 intercross population, confirmed with reciprocal congenic strains and fine mapped with recombinant congenic strains. These efforts identified a ∼ 10-Million base pair (Mbp) interval, underlying Mop2, containing 35 genes. To further reduce the interval, mice from the D2.B6-Mop2-P1 congenic strain were backcrossed to parental D2 mice and two new recombinant strains of interest were generated: D2.B6-Mop2-P1.pD.dB and D2.B6-Mop2-P1.pD.dD. Results obtained from testing these strains in the two-bottle choice drinking paradigm suggest that the gene(s) responsible for the Mop2 QTL is one or more of 22 remaining within the newly defined interval (∼ 7.6 Mbp) which includes Oprm1 and several other genes related to opioid pharmacology. Real-time qRT-PCR analysis of Oprm1 and opioid-related genes Rgs17, Ppp1r14c, Vip, and Iyd revealed both between-strain and within-strain expression differences in comparisons of saline- and morphine-treated B6 and D2 mice. Analysis of Rgs17 protein levels also revealed both between-strain and within-strain differences in comparisons of saline- and morphine-treated B6 and D2 mice. Results suggest that the Mop2 QTL represents the combined influence of multiple genetic variants on morphine preference in these two strains. Relative contributions of each variant remain to be determined.
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Affiliation(s)
- G A Doyle
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
| | - C L Schwebel
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - S E Ruiz
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - A D Chou
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - A T Lai
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - M-J Wang
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - G G Smith
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Research Services, Department of Veterans Affairs Medical Center, Coatesville, PA, USA
| | - R J Buono
- Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA
| | - W H Berrettini
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - T N Ferraro
- Center for Neurobiology and Behavior, Department of Psychiatry, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; Department of Biomedical Sciences, Cooper Medical School of Rowan University, Camden, NJ, USA
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10
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Kabli N, Fan T, O'Dowd BF, George SR. μ-δ opioid receptor heteromer-specific signaling in the striatum and hippocampus. Biochem Biophys Res Commun 2014; 450:906-11. [PMID: 24976397 DOI: 10.1016/j.bbrc.2014.06.099] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/19/2014] [Indexed: 01/28/2023]
Abstract
The μ-δ opioid receptor heteromer activates the pertussis toxin-resistant Gαz GTP-binding protein following stimulation by the δ-agonist deltorphin-II whereas μ- and δ-receptors activate the pertussis toxin-sensitive Gαi3 protein following stimulation by μ- and δ-agonists, respectively. Although the regulation of the μ-δ heteromer is being investigated extensively in vitro, its physiological relevance remains elusive owing to a lack of available molecular tools. We investigated μ-δ heteromer signaling under basal conditions and following prolonged morphine treatment in rodent brain regions highly co-expressing μ- and δ-receptors and Gαz. Deltorphin-II induced Gαz activation in the striatum and hippocampus, demonstrating the presence of μ-δ heteromer signaling in these brain regions. Prolonged morphine treatment, which desensitizes μ- and δ-receptor function, had no effect on μ-δ heteromer signaling in the brain. Our data demonstrate that μ-δ heteromer signaling does not desensitize and is regulated differently from μ- and δ-receptor signaling following prolonged morphine treatment.
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Affiliation(s)
- Noufissa Kabli
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T1R8, Canada; Department of Pharmacology, University of Toronto, Medical Sciences Building RM 4358, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada
| | - Theresa Fan
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T1R8, Canada
| | - Brian F O'Dowd
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T1R8, Canada; Department of Pharmacology, University of Toronto, Medical Sciences Building RM 4358, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada
| | - Susan R George
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, 250 College Street, Toronto, Ontario M5T1R8, Canada; Department of Medicine, University of Toronto, Medical Sciences Building RM 4358, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada; Department of Pharmacology, University of Toronto, Medical Sciences Building RM 4358, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada.
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11
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Nord AS, Blow MJ, Attanasio C, Akiyama JA, Holt A, Hosseini R, Phouanenavong S, Plajzer-Frick I, Shoukry M, Afzal V, Rubenstein JLR, Rubin EM, Pennacchio LA, Visel A. Rapid and pervasive changes in genome-wide enhancer usage during mammalian development. Cell 2014; 155:1521-31. [PMID: 24360275 DOI: 10.1016/j.cell.2013.11.033] [Citation(s) in RCA: 260] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 10/28/2013] [Accepted: 11/22/2013] [Indexed: 12/26/2022]
Abstract
Enhancers are distal regulatory elements that can activate tissue-specific gene expression and are abundant throughout mammalian genomes. Although substantial progress has been made toward genome-wide annotation of mammalian enhancers, their temporal activity patterns and global contributions in the context of developmental in vivo processes remain poorly explored. Here we used epigenomic profiling for H3K27ac, a mark of active enhancers, coupled to transgenic mouse assays to examine the genome-wide utilization of enhancers in three different mouse tissues across seven developmental stages. The majority of the ∼90,000 enhancers identified exhibited tightly temporally restricted predicted activity windows and were associated with stage-specific biological functions and regulatory pathways in individual tissues. Comparative genomic analysis revealed that evolutionary conservation of enhancers decreases following midgestation across all tissues examined. The dynamic enhancer activities uncovered in this study illuminate rapid and pervasive temporal in vivo changes in enhancer usage that underlie processes central to development and disease.
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Affiliation(s)
- Alex S Nord
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Matthew J Blow
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Catia Attanasio
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Jennifer A Akiyama
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Amy Holt
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Roya Hosseini
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Sengthavy Phouanenavong
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Ingrid Plajzer-Frick
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Malak Shoukry
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Veena Afzal
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - John L R Rubenstein
- Department of Psychiatry, Rock Hall, University of California, San Francisco, CA 94158-2324, USA
| | - Edward M Rubin
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA
| | - Len A Pennacchio
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA.
| | - Axel Visel
- Genomics Division, MS 84-171, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; U.S. Department of Energy Joint Genome Institute, Walnut Creek, CA 94598, USA; School of Natural Sciences, University of California, Merced, CA 95343, USA.
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12
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Hultman R, Kumari U, Michel N, Casey PJ. Gαz regulates BDNF-induction of axon growth in cortical neurons. Mol Cell Neurosci 2013; 58:53-61. [PMID: 24321455 DOI: 10.1016/j.mcn.2013.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 11/27/2013] [Accepted: 12/03/2013] [Indexed: 01/26/2023] Open
Abstract
The disruption of neurotransmitter and neurotrophic factor signaling in the central nervous system (CNS) is implicated as the root cause of neuropsychiatric disorders, including schizophrenia, epilepsy, chronic pain, and depression. Therefore, identifying the underlying molecular mechanisms by which neurotransmitter and neurotrophic factor signaling regulates neuronal survival or growth may facilitate identification of more effective therapies for these disorders. Previously, our lab found that the heterotrimeric G protein, Gz, mediates crosstalk between G protein-coupled receptors and neurotrophin signaling in the neural cell line PC12. These data, combined with Gαz expression profiles--predominantly in neuronal cells with higher expression levels corresponding to developmental times of target tissue innervation--suggested that Gαz may play an important role in neurotrophin signaling and neuronal development. Here, we provide evidence in cortical neurons, both manipulated ex vivo and those cultured from Gz knockout mice, that Gαz is localized to axonal growth cones and plays a significant role in the development of axons of cortical neurons in the CNS. Our findings indicate that Gαz inhibits BDNF-stimulated axon growth in cortical neurons, establishing an endogenous role for Gαz in regulating neurotrophin signaling in the CNS.
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Affiliation(s)
- Rainbo Hultman
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857, Republic of Singapore
| | - Udhaya Kumari
- Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857, Republic of Singapore
| | - Nadine Michel
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC 27710, USA
| | - Patrick J Casey
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA; Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA; Program in Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Singapore 169857, Republic of Singapore.
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13
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Kimple ME, Moss JB, Brar HK, Rosa TC, Truchan NA, Pasker RL, Newgard CB, Casey PJ. Deletion of GαZ protein protects against diet-induced glucose intolerance via expansion of β-cell mass. J Biol Chem 2012; 287:20344-55. [PMID: 22457354 DOI: 10.1074/jbc.m112.359745] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Insufficient plasma insulin levels caused by deficits in both pancreatic β-cell function and mass contribute to the pathogenesis of type 2 diabetes. This loss of insulin-producing capacity is termed β-cell decompensation. Our work is focused on defining the role(s) of guanine nucleotide-binding protein (G protein) signaling pathways in regulating β-cell decompensation. We have previously demonstrated that the α-subunit of the heterotrimeric G(z) protein, Gα(z), impairs insulin secretion by suppressing production of cAMP. Pancreatic islets from Gα(z)-null mice also exhibit constitutively increased cAMP production and augmented glucose-stimulated insulin secretion, suggesting that Gα(z) is a tonic inhibitor of adenylate cyclase, the enzyme responsible for the conversion of ATP to cAMP. In the present study, we show that mice genetically deficient for Gα(z) are protected from developing glucose intolerance when fed a high fat (45 kcal%) diet. In these mice, a robust increase in β-cell proliferation is correlated with significantly increased β-cell mass. Further, an endogenous Gα(z) signaling pathway, through circulating prostaglandin E activating the EP3 isoform of the E prostanoid receptor, appears to be up-regulated in insulin-resistant, glucose-intolerant mice. These results, along with those of our previous work, link signaling through Gα(z) to both major aspects of β-cell decompensation: insufficient β-cell function and mass.
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Affiliation(s)
- Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705, USA.
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Abstract
Opioid analgesics elicit their effects via activation of the mu-opioid receptor (MOR), a G protein-coupled receptor known to interact with Gα(i/o)-type G proteins. Work in vitro has suggested that MOR couples preferentially to the abundant brain Gα(i/o) isoform, Gα(o). However, studies in vivo evaluating morphine-mediated antinociception have not supported these findings. The aim of the present work was to evaluate the contribution of Gα(o) to MOR-dependent signaling by measuring both antinociceptive and biochemical endpoints in a Gα(o) null transgenic mouse strain. Male wild-type and Gα(o) heterozygous null (Gα(o) ⁺/⁻) mice were tested for opioid antinociception in the hot plate test or the warm-water tail withdrawal test as measures of supraspinal or spinal antinociception, respectively. Reduction in Gα(o) levels attenuated the supraspinal antinociception produced by morphine, methadone, and nalbuphine, with the magnitude of suppression dependent on agonist efficacy. This was explained by a reduction in both high-affinity MOR expression and MOR agonist-stimulated G protein activation in whole brain homogenates from Gα(o) ⁺/⁻ and Gα(o) homozygous null (Gα(o)⁻/⁻) mice, compared with wild-type littermates. On the other hand, morphine spinal antinociception was not different between Gα(o) ⁺/⁻ and wild-type mice and high-affinity MOR expression was unchanged in spinal cord tissue. However, the action of the partial agonist nalbuphine was compromised, showing that reduction in Gα(o) protein does decrease spinal antinociception, but suggesting a higher Gα(o) protein reserve. These results provide the first in vivo evidence that Gα(o) contributes to maximally efficient MOR signaling and antinociception.
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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'.
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Affiliation(s)
- Elsa M Valdizán
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad de Cantabria, 39011 Santander, Cantabria, Spain
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16
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Nik-Zainal S, Strick R, Storer M, Huang N, Rad R, Willatt L, Fitzgerald T, Martin V, Sandford R, Carter NP, Janecke AR, Renner SP, Oppelt PG, Oppelt P, Schulze C, Brucker S, Hurles M, Beckmann MW, Strissel PL, Shaw-Smith C. High incidence of recurrent copy number variants in patients with isolated and syndromic Müllerian aplasia. J Med Genet 2011; 48:197-204. [PMID: 21278390 PMCID: PMC3322361 DOI: 10.1136/jmg.2010.082412] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Congenital malformations involving the Müllerian ducts are observed in around 5% of infertile women. Complete aplasia of the uterus, cervix, and upper vagina, also termed Müllerian aplasia or Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome, occurs with an incidence of around 1 in 4500 female births, and occurs in both isolated and syndromic forms. Previous reports have suggested that a proportion of cases, especially syndromic cases, are caused by variation in copy number at different genomic loci. METHODS In order to obtain an overview of the contribution of copy number variation to both isolated and syndromic forms of Müllerian aplasia, copy number assays were performed in a series of 63 cases, of which 25 were syndromic and 38 isolated. RESULTS A high incidence (9/63, 14%) of recurrent copy number variants in this cohort is reported here. These comprised four cases of microdeletion at 16p11.2, an autism susceptibility locus not previously associated with Müllerian aplasia, four cases of microdeletion at 17q12, and one case of a distal 22q11.2 microdeletion. Microdeletions at 16p11.2 and 17q12 were found in 4/38 (10.5%) cases with isolated Müllerian aplasia, and at 16p11.2, 17q12 and 22q11.2 (distal) in 5/25 cases (20%) with syndromic Müllerian aplasia. CONCLUSION The finding of microdeletion at 16p11.2 in 2/38 (5%) of isolated and 2/25 (8%) of syndromic cases suggests a significant contribution of this copy number variant alone to the pathogenesis of Müllerian aplasia. Overall, the high incidence of recurrent copy number variants in all forms of Müllerian aplasia has implications for the understanding of the aetiopathogenesis of the condition, and for genetic counselling in families affected by it.
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Affiliation(s)
| | - Reiner Strick
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Mekayla Storer
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
- Institute of Child Health, London, UK
| | - Ni Huang
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Roland Rad
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Lionel Willatt
- Regional Cytogenetics Laboratory, Addenbrooke’s Hospital, Cambridge, UK
| | | | - Vicki Martin
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
- Institute of Child Health, London, UK
| | - Richard Sandford
- Department of Clinical Genetics, Addenbrooke’s Hospital, Cambridge, UK
| | | | - Andreas R Janecke
- Department of Pediatrics II, Innsbruck Medical University, Innsbruck, Austria
- Division of Human Genetics, Innsbruck Medical University, Innsbruck, Austria
| | - Stefan P Renner
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Patricia G Oppelt
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Peter Oppelt
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Christine Schulze
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Sara Brucker
- University-Clinic, Department of Obstetrics and Gynecology, Tübingen, Germany
| | | | - Matthias W Beckmann
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Pamela L Strissel
- University-Clinic Erlangen, Department of Obstetrics and Gynecology, Erlangen, Germany
| | - Charles Shaw-Smith
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
- Institute of Child Health, London, UK
- Institute of Biomedical and Clinical Science, Peninsula College of Medicine and Dentistry, University of Exeter, Barrack Road, Exeter EX2 5DW, UK
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Expression of Gαz in C2C12 cells restrains myogenic differentiation. Cell Signal 2011; 23:389-97. [DOI: 10.1016/j.cellsig.2010.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Revised: 09/16/2010] [Accepted: 10/01/2010] [Indexed: 10/19/2022]
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Harris MJ, Juriloff DM. An update to the list of mouse mutants with neural tube closure defects and advances toward a complete genetic perspective of neural tube closure. ACTA ACUST UNITED AC 2010; 88:653-69. [PMID: 20740593 DOI: 10.1002/bdra.20676] [Citation(s) in RCA: 238] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The number of mouse mutants and strains with neural tube defects (NTDs) now exceeds 240, including 205 representing specific genes, 30 for unidentified genes, and 9 multifactorial strains. These mutants identify genes needed for embryonic neural tube closure. Reports of 50 new NTD mutants since our 2007 review (Harris and Juriloff, 2007) were considered in relation to the previously reviewed mutants to obtain new insights into mechanisms of NTD etiology. In addition to null mutations, some are hypomorphs or conditional mutants. Some mutations do not cause NTDs on their own, but do so in digenic, trigenic, and oligogenic combinations, an etiology that likely parallels the nature of genetic etiology of human NTDs. Mutants that have only exencephaly are fourfold more frequent than those that have spina bifida aperta with or without exencephaly. Many diverse cellular functions and biochemical pathways are involved; the NTD mutants draw new attention to chromatin modification (epigenetics), the protease-activated receptor cascade, and the ciliopathies. Few mutants directly involve folate metabolism. Prevention of NTDs by maternal folate supplementation has been tested in 13 mutants and reduces NTD frequency in six diverse mutants. Inositol reduces spina bifida aperta frequency in the curly tail mutant, and three new mutants involve inositol metabolism. The many NTD mutants are the foundation for a future complete genetic understanding of the processes of neural fold elevation and fusion along mechanistically distinct cranial-caudal segments of the neural tube, and they point to several candidate processes for study in human NTD etiology.
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Affiliation(s)
- Muriel J Harris
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.
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Effect of KEPI (Ppp1r14c) deletion on morphine analgesia and tolerance in mice of different genetic backgrounds: when a knockout is near a relevant quantitative trait locus. Neuroscience 2009; 165:882-95. [PMID: 19819304 DOI: 10.1016/j.neuroscience.2009.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2009] [Revised: 09/23/2009] [Accepted: 10/03/2009] [Indexed: 01/01/2023]
Abstract
We previously identified KEPI as a morphine-regulated gene using subtractive hybridization and differential display PCR. Upon phosphorylation by protein kinase C, KEPI becomes a powerful inhibitor of protein phosphatase 1. To gain insights into KEPI functions, we created KEPI knockout (KO) mice on mixed 129S6xC57BL/6 genetic backgrounds. KEPI maps onto mouse chromosome 10 close to the locus that contains the mu-opioid receptor (Oprm1) and provides a major quantitative trait locus for morphine effects. Analysis of single nucleotide polymorphisms in and near the Oprm1 locus identified a doubly-recombinant mouse with C57BL/6 markers within 1 Mb on either side of the KEPI deletion. This strategy minimized the amount of 129S6 DNA surrounding the transgene and documented the C57BL/6 origin of the Oprm1 gene in this founder and its offspring. Recombinant KEPIKO mice displayed (a) normal analgesic responses and normal locomotion after initial morphine treatments, (b) accelerated development of tolerance to analgesic effects of morphine, (c) elevated activity of protein phosphatase 1 in thalamus, (d) attenuated morphine reward as assessed by conditioned place preference. These data support roles for KEPI action in adaptive responses to repeated administration of morphine that include analgesic tolerance and drug reward.
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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]
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Cho H, Kehrl JH. Chapter 9 Regulation of Immune Function by G Protein‐Coupled Receptors, Trimeric G Proteins, and RGS Proteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 86:249-98. [DOI: 10.1016/s1877-1173(09)86009-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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van den Buuse M, Martin S, Holgate J, Matthaei K, Hendry I. Mice deficient in the alpha subunit of G(z) show changes in pre-pulse inhibition, anxiety and responses to 5-HT(1A) receptor stimulation, which are strongly dependent on the genetic background. Psychopharmacology (Berl) 2007; 195:273-83. [PMID: 17684732 DOI: 10.1007/s00213-007-0888-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Accepted: 07/02/2007] [Indexed: 10/23/2022]
Abstract
RATIONALE G(z), a member of the G(i) G protein family, is involved in the coupling of dopaminergic and serotonergic receptors. In the present study, we investigated behaviour of mice deficient in the alpha subunit of G(z) and focused on pre-pulse inhibition (PPI) and anxiety-like responses and the role of serotonin-1A (5-HT(1A)) receptors. MATERIALS AND METHODS We compared male and female wild-type and knock-out mice on either a C57Bl/6 or Balb/c background. We used automated startle boxes to assess startle and PPI and elevated plus maze to assess anxiety-like behaviours. RESULTS Balb/c mice showed higher baseline PPI than C57Bl/6 mice, and there was no difference between the genotypes. The 5-HT(1A) receptor agonist, 8-hydroxy-di-propylaminotetralin (8-OH-DPAT), had no effect on PPI in C57Bl/6 mice but markedly increased PPI in Balb/c mice, with the effect being attenuated in Galpha(z) knock-outs. On the elevated plus maze, there was little effect of the knock-out or 8-OH-DPAT in C57Bl/6 mice, whereas in Balb/c mice, Galpha(z) knock-outs showed a phenotype of high levels of anxiety-like behaviour. 8-OH-DPAT was anxiogenic in Balb/c mice, but this effect was attenuated in Galpha(z) knock-outs. CONCLUSIONS 5-HT(1A) receptors couple to G(z). In a strictly background strain-dependent manner, Galpha(z) knock-out mice display high levels of anxiety-like behaviour and are less sensitive to the action of 8-OH-DPAT. Balb/c mice show much more clear effects of the Galpha(z) knock-out than C57Bl/6 mice, which are often considered the standard background strain for genetic modifications. Therefore, our results suggest caution when studying the behavioural effects of genetic modifications only in C57Bl/6 mice.
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Affiliation(s)
- Maarten van den Buuse
- Behavioural Neuroscience Laboratory, Mental Health Research Institute, 155 Oak Street, Parkville, Victoria 3052, Australia.
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23
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Candidate gene polymorphisms predicting individual sensitivity to opioids. Naunyn Schmiedebergs Arch Pharmacol 2007; 377:269-81. [DOI: 10.1007/s00210-007-0205-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 10/18/2007] [Indexed: 11/26/2022]
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Martini L, Whistler JL. The role of mu opioid receptor desensitization and endocytosis in morphine tolerance and dependence. Curr Opin Neurobiol 2007; 17:556-64. [DOI: 10.1016/j.conb.2007.10.004] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 10/10/2007] [Accepted: 10/16/2007] [Indexed: 12/12/2022]
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25
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Leck KJ, Blaha CD, Matthaei KI, Forster GL, Holgate J, Hendry IA. Gz proteins are functionally coupled to dopamine D2-like receptors in vivo. Neuropharmacology 2006; 51:597-605. [PMID: 16814816 DOI: 10.1016/j.neuropharm.2006.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 05/03/2006] [Accepted: 05/03/2006] [Indexed: 11/18/2022]
Abstract
The receptors that couple to the G protein Gz in vivo are still relatively unknown. In this study, we investigated the effects of various dopamine receptor agonists in a mouse deficient in the alpha subunit of Gz. The dopamine D1-like receptor agonist SKF38393 stimulated comparable locomotor activity in both wildtype mice and mice lacking Galphaz. In contrast, the dopamine D2-like receptor agonist quinpirole suppressed locomotor activity in both groups of mice, but this suppression was significantly smaller in Galphaz knockout mice. Consistent with these behavioural observations, quinpirole inhibition of dopamine release in the forebrain nucleus accumbens evoked by electrical stimulation of dopamine axons was significantly attenuated in mice lacking Galphaz. In addition, hypothermia and adrenocorticotropic hormone release resulting from activation of dopamine D2-like receptors were also significantly reduced in Galphaz knockout mice. However, adrenocorticotropic hormone secretion induced by corticotrophin releasing hormone and the serotonin 1A receptor agonist 8-hydroxy-dipropylamino-tetralin were similar between wildtype and Galphaz knockout mice. Western blot analysis showed that the expression levels of Galphai, Galphao, Galphas, Galphaq and Gbeta were the same in the brains of mice of both genotypes. Overall, our data suggest that Gz proteins are functionally coupled to dopamine D2-like receptors in vivo.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- 8-Hydroxy-2-(di-n-propylamino)tetralin/pharmacology
- Adrenocorticotropic Hormone/blood
- Animals
- Behavior, Animal/drug effects
- Behavior, Animal/physiology
- Blotting, Western/methods
- Body Temperature/drug effects
- Body Temperature/physiology
- Dopamine/metabolism
- Dopamine Agonists/pharmacology
- GTP-Binding Protein alpha Subunits/deficiency
- GTP-Binding Protein alpha Subunits/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Motor Activity/drug effects
- Motor Activity/physiology
- Nucleus Accumbens/drug effects
- Quinpirole/pharmacology
- Receptors, Dopamine D2/physiology
- Serotonin Receptor Agonists/pharmacology
- Tetrahydronaphthalenes/pharmacology
- Time Factors
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Affiliation(s)
- Kwong J Leck
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT Australia, 0200
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26
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Devidze N, Lee AW, Zhou J, Pfaff DW. CNS arousal mechanisms bearing on sex and other biologically regulated behaviors. Physiol Behav 2006; 88:283-93. [PMID: 16769096 DOI: 10.1016/j.physbeh.2006.05.030] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It now seems possible to move beyond analyzing only the mechanisms for specific sexual behaviors to the analysis of 'generalized arousal' that underlies all motivated behaviors. Our science has advanced sufficiently to attack mechanisms linking specific motivations to these general arousal mechanisms that intrinsically activate all biologically-regulated behaviors including ingestive behaviors. Learning from the well-developed reproductive behavior paradigm, we know that sex hormone effects on hypothalamic neurons have been studied to a point where receptor mechanisms are relatively well understood, a neural circuit for a sex steroid-dependent behavior has been worked out, and several functional genomic regulations have been discovered. Here we focus for the first time on three chemical systems that signal 'generalized arousal' and which impact hormone-dependent hypothalamic neurons of importance to sexual arousal: histamine, norepinephrine and enkephalin. Progress in linking generalized arousal to specific motivational mechanisms is reviewed.
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Affiliation(s)
- Nino Devidze
- Laboratory of Neurobiology and Behavior, Box 275, The Rockefeller University, New York, NY 10021, USA.
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27
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Lee AW, Devidze N, Pfaff DW, Zhou J. Functional genomics of sex hormone-dependent neuroendocrine systems: specific and generalized actions in the CNS. PROGRESS IN BRAIN RESEARCH 2006; 158:243-72. [PMID: 17027700 DOI: 10.1016/s0079-6123(06)58012-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Sex hormone effects on hypothalamic neurons have been worked out to a point where receptor mechanisms are relatively well understood, a neural circuit for a sex steroid-dependent behavior has been determined, and several functional genomic regulations have been discovered and conceptualized. With that knowledge in hand, we approach deeper problems of explaining sexual arousal and generalized CNS arousal. After a brief summary of arousal mechanisms, we focus on three chemical systems which signal generalized arousal and impact hormone-dependent hypothalamic neurons of behavioral importance: histamine, norepinephrine and enkephalin.
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Affiliation(s)
- Anna W Lee
- Laboratory of Neurobiology and Behavior, Box 275, The Rockefeller University, New York, NY 10021, USA
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28
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van den Buuse M, Martin S, Brosda J, Leck KJ, Matthaei KI, Hendry I. Enhanced effect of dopaminergic stimulation on prepulse inhibition in mice deficient in the alpha subunit of G(z). Psychopharmacology (Berl) 2005; 183:358-67. [PMID: 16220329 DOI: 10.1007/s00213-005-0181-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 08/22/2005] [Indexed: 11/29/2022]
Abstract
RATIONALE G(z) is a member of the G(i) G protein family associated with dopamine D2-like receptors; however, its functions remain relatively unknown. The aim of the present study was to investigate prepulse inhibition (PPI) of acoustic startle, locomotor hyperactivity and dopamine D2 receptor binding in mice deficient in the alpha subunit of G(z). METHODS We used automated startle boxes to assess startle and PPI after treatment with saline, amphetamine, apomorphine or MK-801. We used photocell cages to quantitate locomotor activity after amphetamine treatment. Dopamine D2 receptor density was determined by autoradiography. RESULTS Startle responses and baseline PPI were not different between the Galpha(z) knockout mice and wild-type controls (average PPI 46+/-4 vs 49+/-3%, respectively). Amphetamine treatment caused a marked disruption of PPI in Galpha(z) knockouts (average PPI 22+/-2%), but less so in controls (average PPI 42+/-3%). Similar genotype-dependent responses were seen after apomorphine treatment (average PPI 23+/-3% vs 40+/-3%), but not after MK-801 treatment (average PPI 29+/-5 vs 33+/-2%). Amphetamine-induced locomotor hyperactivity was greater in Galpha(z) knockouts than in controls. There was no difference in the density of dopamine D2 receptors in nucleus accumbens. CONCLUSIONS Mice deficient in the alpha subunit of G(z) show enhanced sensitivity to the disruption of PPI and locomotor hyperactivity caused by dopaminergic stimulation. These results suggest a possible role for G(z) in neuropsychiatric illnesses with presumed dopaminergic hyperactivity, such as schizophrenia.
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Affiliation(s)
- M van den Buuse
- Behavioural Neuroscience Laboratory, Mental Health Research Institute of Victoria, 155 Oak Street, Parkville, Victoria 3052, Australia.
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29
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Abstract
Heterotrimeric G proteins are key players in transmembrane signaling by coupling a huge variety of receptors to channel proteins, enzymes, and other effector molecules. Multiple subforms of G proteins together with receptors, effectors, and various regulatory proteins represent the components of a highly versatile signal transduction system. G protein-mediated signaling is employed by virtually all cells in the mammalian organism and is centrally involved in diverse physiological functions such as perception of sensory information, modulation of synaptic transmission, hormone release and actions, regulation of cell contraction and migration, or cell growth and differentiation. In this review, some of the functions of heterotrimeric G proteins in defined cells and tissues are described.
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Affiliation(s)
- Nina Wettschureck
- Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, D-69120 Heidelberg, Germany
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30
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Oleskevich S, Leck KJ, Matthaei K, Hendry IA. Enhanced serotonin response in the hippocampus of Galphaz protein knock-out mice. Neuroreport 2005; 16:921-5. [PMID: 15931062 DOI: 10.1097/00001756-200506210-00009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The serotonin-1A [5-hydroxytryptamine 1A (5HT1A)] receptor is important for emotional and homeostatic processes in the central nervous system. In the hippocampus, the 5HT1A receptor couples to inhibitory Gi/o proteins to decrease pyramidal cell excitability. Here we investigate the 5HT1A receptor in a mouse deficient in the alpha-subunit of Gz protein (Galphaz knock-out). Behavioural tests showed heightened anxiety and depression-like behaviour in the Galphaz knock-out mice. Whole-cell recording in CA1 pyramidal neurons showed a significantly greater 5HT1A receptor-mediated potassium current in Galphaz knock-out mice. The effect was independent of 5HT4 receptors as the slow after-hyperpolarization was unaffected and a slow depolarization was absent in the Galphaz knock-out mice. Other receptors linked to Gi/o proteins [gamma-aminobutyric acid type B receptor (GABAB), adenosine A1 and muscarinic acetylcholine receptors] were not affected in Galphaz knock-out mice. These results suggest that the 5HT1A receptor may be linked to Galphaz protein, as reported previously in cell culture but shown here in an intact neural network.
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31
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Garzón J, Rodríguez-Muñoz M, Sánchez-Blázquez P. Morphine alters the selective association between mu-opioid receptors and specific RGS proteins in mouse periaqueductal gray matter. Neuropharmacology 2005; 48:853-68. [PMID: 15829256 DOI: 10.1016/j.neuropharm.2005.01.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2004] [Revised: 12/03/2004] [Accepted: 01/06/2005] [Indexed: 11/28/2022]
Abstract
In the CNS, several regulators of G-protein signalling (RGS) modulate the activity of mu-opioid receptors. In pull-down assays performed on membranes from mouse periaqueductal gray matter (PAG), mu-opioid receptors co-precipitated with delta-opioid receptors, Gi/o/z/q proteins, and the regulators of G-protein signalling RGS4, RGS9-2, RGS14, RGSZ1 and RGSZ2. No RGS2, RGS7, RGS10 and RGS11 proteins were associated with the mu receptors in these PAG membranes. In mice, an intracerebroventricular dose of 10 nmol morphine produced acute tolerance at mu receptors but did not disrupt the co-precipitation of mu-delta receptor complexes. However, this opioid reduced by more than 50% the co-precipitation of G alpha i/o/z subunits with mu receptors, and altered their association with some of the RGS proteins at 30 min, 3 h and 24 h after its administration. The association of RGS9-2 with mu receptors diminished by 30-40% 24 h after the administration of morphine, while that of RGSZ2 and of RGSZ1 increased. Morphine treatment recruited RGS4 to the PAG membranes, and 30 min and 3 h after the opioid challenge its association with mu receptors had increased. However, 24 h after morphine administration, the co-precipitation of RGS4 had decreased by about 30%. The opioid produced no change in the membrane levels of RGS9-2, RGS14, RGSZ1 and RGSZ2. Thus, in PAG synaptosomal membranes, a dynamic and selective link exists between, mu-opioid receptors, Gi/o/z proteins and certain RGS proteins.
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MESH Headings
- Analgesics, Opioid/pharmacology
- Animals
- Autoradiography
- Cell Membrane/drug effects
- Cell Membrane/metabolism
- Chemical Precipitation
- Chromatography, Affinity/methods
- Dose-Response Relationship, Drug
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Immunoblotting/methods
- Iodine Isotopes/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Morphine/pharmacology
- Narcotics/pharmacology
- Periaqueductal Gray/drug effects
- Periaqueductal Gray/metabolism
- RGS Proteins/classification
- RGS Proteins/metabolism
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, mu/deficiency
- Receptors, Opioid, mu/metabolism
- Time Factors
- beta-Endorphin/pharmacology
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Affiliation(s)
- Javier Garzón
- Neurofarmacología, Instituto de Neurobiología Santiago Ramón y Cajal, Consejo Superior de Investigaciones Científicas, Doctor Arce 37, E-28002 Madrid, Spain.
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32
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Garzón J, Rodríguez-Muñoz M, López-Fando A, Sánchez-Blázquez P. Activation of μ-Opioid Receptors Transfers Control of Gα Subunits to the Regulator of G-protein Signaling RGS9-2. J Biol Chem 2005; 280:8951-60. [PMID: 15632124 DOI: 10.1074/jbc.m407005200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In mouse periaqueductal gray matter (PAG) membranes, the mu-opioid receptor (MOR) coprecipitated the alpha-subunits of the Gi/o/z/q/11 proteins, the Gbeta1/2 subunits, and the regulator of G-protein signaling RGS9-2 and its partner protein Gbeta5. RGS7 and RGS11 present in this neural structure showed no association with MOR. In vivo intracerebroventricular injection of morphine did not alter MOR immunoreactivity, but 30 min and 3 h after administration, the coprecipitation of Galpha subunits with MORs was reduced by up to 50%. Furthermore, the association between Galpha subunits and RGS9-2 proteins was increased. Twenty-four hours after receiving intracerebroventricular morphine, the Galpha subunits left the RGS9-2 proteins and re-associated with the MORs. However, doses of the opioid able to induce tolerance promoted the stable transfer of Galpha subunits to the RGS9-2 control. This was accompanied by Ser phosphorylation of RGS9-2 proteins, which increased their co-precipitation with 14-3-3 proteins. In the PAG membranes of morphine-desensitized mice, the capacity of the opioid to stimulate G-protein-related guanosine 5'-O-(3-[35S]thiotriphosphate) binding as well as low Km GTPase activity was attenuated. The in vivo knockdown of RGS9-2 expression prevented morphine from altering the association between MORs and G-proteins, and tolerance did not develop. In PAG membranes from RGS9-2 knockdown mice, morphine showed full capacity to activate G-proteins. Thus, the tolerance that develops following an adequate dose of morphine is caused by the stabilization and retention of MOR-activated Galpha subunits by RGS9-2 proteins. This multistep process is initiated by the morphine-induced transfer of MOR-associated Galpha subunits to the RGS9-2 proteins, followed by Ser phosphorylation of the latter and their binding to 14-3-3 proteins. This regulatory mechanism probably precedes the loss of MORs from the cell membrane, which has been observed with other opioid agonists.
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Affiliation(s)
- Javier Garzón
- Department of Neuropharmacology, Cajal Institute, Consejo Superior de Investigaciones Científicas, E-28002 Madrid, Spain.
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33
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Abstract
Opioid receptors belong to the large superfamily of seven transmembrane-spanning (7TM) G protein-coupled receptors (GPCRs). As a class, GPCRs are of fundamental physiological importance mediating the actions of the majority of known neurotransmitters and hormones. Opioid receptors are particularly intriguing members of this receptor family. They are activated both by endogenously produced opioid peptides and by exogenously administered opiate compounds, some of which are not only among the most effective analgesics known but also highly addictive drugs of abuse. A fundamental question in addiction biology is why exogenous opioid drugs, such as morphine and heroin, have a high liability for inducing tolerance, dependence, and addiction. This review focuses on many aspects of opioid receptors with the aim of gaining a greater insight into mechanisms of opioid tolerance and dependence.
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Affiliation(s)
- Maria Waldhoer
- Ernest Gallo Clinic and Research Center, University of California, San Francisco, Emeryville, California 94608, USA.
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34
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Dutt P, Jaffe AB, Merdek KD, Hall A, Toksoz D. Galphaz inhibits serum response factor-dependent transcription by inhibiting Rho signaling. Mol Pharmacol 2004; 66:1508-16. [PMID: 15326221 DOI: 10.1124/mol.104.002949] [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: 12/20/2022] Open
Abstract
Galpha12/13 or Galphaq signals induce activation of Rho GTPase, leading to serum response factor (SRF)-mediated gene transcription and actin cytoskeletal organization; however, less is known regarding how Rho pathway signals are down-regulated. Here we report that Galphaz signals inhibit serum response factor (SRF)-dependent transcription. Galphaz expression inhibits Galpha12/13-, Galphaq-, and Rho guanine nucleotide exchange factor (GEF)-induced serum response element (SRE) reporter activation in human embryonic kidney 293T and PC-12 cells. Expression of Galphaz mutants with defective fatty acylation has no inhibitory effect. Expression of Galphaz, but not Galphai, attenuates serum-induced SRE reporter activation, suggesting that Galphaz can down-regulate endogenous signals leading to SRF. Whereas Galphaz also blocks SRE reporter induction by the activated mutant RhoAL63, it does not affect Galpha12- or Rho GEF-induced RhoA activation or RhoAL63-GTP binding in vivo. Moreover, Galphaz does not inhibit SRE reporter induction by an activated form of Rho kinase. Because Galphaz inhibits RhoAL63/A188-induced reporter activation, phosphorylation of RhoA on serine 188 does not seem to be involved; furthermore, RhoA subcellular localization was not affected. Use of pharmacologic inhibitors implies that Galphaz-induced reduction of SRE reporter activation occurs via a mechanism other than adenylate cyclase modulation. These findings suggest that Galphaz signals may attenuate Rho-induced stimulation of SRF-mediated transcription.
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Affiliation(s)
- Parmesh Dutt
- Physiology Department, Tufts University School of Medicine, Boston, Massachusetts 02111, USA
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35
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Embry AC, Glick JL, Linder ME, Casey PJ. Reciprocal Signaling between the Transcriptional Co-Factor Eya2 and Specific Members of the Gαi Family. Mol Pharmacol 2004; 66:1325-31. [PMID: 15308761 DOI: 10.1124/mol.104.004093] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
As part of a program to elucidate signaling processes controlled by the heterotrimeric G protein Galphaz, a human fetal brain cDNA library was screened for proteins that specifically interact with the activated form of Galphaz. One of the most-encountered molecules in this screen was Eya2, a member of the Eyes absent family of proteins. Mammalian Eya proteins are predominantly cytosolic proteins that are known to interact with members of the Sine oculis (Six) family of homeodomain transcription factors. This interaction facilitates the translocation of Eya into the nucleus, where the Eya/Six complex regulates transcription during critical stages of embryonic development. In vitro binding studies confirmed that Galphaz interacts with Eya2 in an activation-dependent fashion; furthermore, most other members of the Galphai family including Galphai1, Galphai2, and Galphai3 were found to interact with Eya2. It is interesting that one of the most abundant Galphai proteins, Galphao, did not interact with Eya2. Coexpression of the activated forms of Galphai1, Galphai2, and Galphai3, but not Galphao, with Eya2 recruited Eya2 to the plasma membrane, prevented Eya2 translocation into the nucleus, and abrogated Eya2/Six4-mediated transcription. In addition, Eya2 impinged on G protein-mediated signaling, as evidenced by its ability to relieve Galphai2-mediated inhibition of adenylyl cyclase. These results demonstrate that the interaction between the Galphai proteins and Eya2 may impact on seemingly disparate regulatory events involving both classes of proteins.
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Affiliation(s)
- Alan C Embry
- Department of Biochemistry, Duke University Medical Center, Box 3813, Durham, NC 27710-3813, USA
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36
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Leck KJ, Bartlett SE, Smith MT, Megirian D, Holgate J, Powell KL, Matthaei KI, Hendry IA. Deletion of guanine nucleotide binding protein alpha z subunit in mice induces a gene dose dependent tolerance to morphine. Neuropharmacology 2004; 46:836-46. [PMID: 15033343 DOI: 10.1016/j.neuropharm.2003.11.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2002] [Revised: 09/30/2003] [Accepted: 11/21/2003] [Indexed: 11/23/2022]
Abstract
The mechanism underlying the development of tolerance to morphine is still incompletely understood. Morphine binds to opioid receptors, which in turn activates downstream second messenger cascades through heterotrimeric guanine nucleotide binding proteins (G proteins). In this paper, we show that G(z), a member of the inhibitory G protein family, plays an important role in mediating the analgesic and lethality effects of morphine after tolerance development. We blocked signaling through the G(z) second messenger cascade by genetic ablation of the alpha subunit of the G protein in mice. The Galpha(z) knockout mouse develops significantly increased tolerance to morphine, which depends on Galpha(z) gene dosage. Further experiments demonstrate that the enhanced morphine tolerance is not caused by pharmacokinetic and behavioural learning mechanisms. The results suggest that G(z) signaling pathways are involved in transducing the analgesic and lethality effects of morphine following chronic morphine treatment.
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Affiliation(s)
- K J Leck
- Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Canberra, ACT 0200, Australia
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37
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Abstract
The G-protein-mediated signaling system has evolved as one of the most widely used transmembrane signaling mechanisms in eukaryotic organisms. Mammalian cells express many G-protein-coupled receptors as well as several types of heterotrimeric G-proteins and effectors. This review focuses on recent data from studies in mutant mice, which have elucidated some of the roles of G-protein-mediated signaling in physiology and pathophysiology.
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Affiliation(s)
- Nina Wettschureck
- Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120, Heidelberg, Germany.
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38
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Turic D, Langley K, Kirov G, Owen MJ, Thapar A, O'Donovan MC. Direct analysis of the genes encoding G proteins G alpha T2, G alpha o, G alpha Z in ADHD. Am J Med Genet B Neuropsychiatr Genet 2004; 127B:68-72. [PMID: 15108183 DOI: 10.1002/ajmg.b.20173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We have followed up the extensive replicated evidence that the dopamine DRD4 receptor is involved in the aetiology of ADHD by undertaking direct analysis of genes encoding other proteins in this effector system. We prioritised the genes encoding G protein alpha subunits G alpha(T2), G alpha(o), G alpha(Z) as these have been shown to transduce the effects of ligand binding at DRD4. We screened the exons of all three genes for sequence variation in 28 unrelated subjects with ADHD and identified 13 novel polymorphisms. All were tested for possible association with ADHD using a combination of pooled and individual genotyping. The results of our study do not suggest that polymorphisms in these genes contribute to susceptibility to ADHD.
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Affiliation(s)
- D Turic
- Department of Psychological Medicine, University of Wales College of Medicine, Heath Park, Cardiff, United Kingdom
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39
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Zachariou V, Georgescu D, Sanchez N, Rahman Z, DiLeone R, Berton O, Neve RL, Sim-Selley LJ, Selley DE, Gold SJ, Nestler EJ. Essential role for RGS9 in opiate action. Proc Natl Acad Sci U S A 2003; 100:13656-61. [PMID: 14595021 PMCID: PMC263869 DOI: 10.1073/pnas.2232594100] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2003] [Indexed: 11/18/2022] Open
Abstract
Regulators of G protein signaling (RGS) are a family of proteins known to accelerate termination of effector stimulation after G protein receptor activation. RGS9-2, a brain-specific splice variant of the RGS9 gene, is highly enriched in striatum and also expressed at much lower levels in periaqueductal gray and spinal cord, structures known to mediate various actions of morphine and other opiates. Morphine exerts its acute rewarding and analgesic effects by activation of inhibitory guanine nucleotide-binding regulatory protein-coupled opioid receptors, whereas chronic morphine causes addiction, tolerance to its acute analgesic effects, and profound physical dependence by sustained activation of these receptors. We show here that acute morphine administration increases expression of RGS9-2 in NAc and the other CNS regions, whereas chronic exposure decreases RGS9-2 levels. Mice lacking RGS9 show enhanced behavioral responses to acute and chronic morphine, including a dramatic increase in morphine reward, increased morphine analgesia with delayed tolerance, and exacerbated morphine physical dependence and withdrawal. These findings establish RGS9 as a potent negative modulator of opiate action in vivo, and suggest that opiate-induced changes in RGS9 levels contribute to the behavioral and neural plasticity associated with chronic opiate administration.
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Affiliation(s)
- Venetia Zachariou
- Department of Psychiatry and Center for Basic Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390-9070, USA
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40
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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.
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Affiliation(s)
- Yaping Tu
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
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41
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Offermanns S. G-proteins as transducers in transmembrane signalling. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 83:101-30. [PMID: 12865075 DOI: 10.1016/s0079-6107(03)00052-x] [Citation(s) in RCA: 196] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The G-protein-mediated signalling system has evolved as one of the most widely used transmembrane signalling mechanisms in mammalian organisms. All mammalian cells express G-protein-coupled receptors as well as several types of heterotrimeric G-proteins and effectors. G-protein-mediated signalling is involved in many physiological and pathological processes. This review summarizes some general aspects of G-protein-mediated signalling and focusses on recent data especially from studies in mutant mice which have elucidated some of the cellular and biological functions of heterotrimeric G-prtoteins.
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Affiliation(s)
- Stefan Offermanns
- Institute of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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Tso PH, Wong YH. Molecular basis of opioid dependence: role of signal regulation by G-proteins. Clin Exp Pharmacol Physiol 2003; 30:307-16. [PMID: 12859419 DOI: 10.1046/j.1440-1681.2003.03835.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
1. Morphine and opiate narcotics are potent analgesics that have a high propensity to induce tolerance and physical dependence following their repeated administration. 2. The molecular basis of opiate dependence has not been completely elucidated, although the participation of opioid receptors is a prerequisite. Cellular dependence on opioids is believed to result from the chronic stimulation of opioid-regulated signalling networks. 3. As G-protein-coupled receptors, the opioid receptors must rely on heterotrimeric G-proteins for signal transduction. Recent advances in our understanding of G-protein signalling have unveiled novel signalling molecules and mechanisms, some of which may be intricately involved in the manifestation of opiate dependence. 4. In the present review, we will attempt to trace chronic opioid signals along elaborate G-protein-regulated pathways.
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Affiliation(s)
- Prudence H Tso
- Department of Biochemistry, the Molecular Neuroscience Center and The Biotechnology Research Institute, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
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Nagahama M, Usui S, Shinohara T, Yamaguchi T, Tani K, Tagaya M. Inactivation of Galpha(z) causes disassembly of the Golgi apparatus. J Cell Sci 2002; 115:4483-93. [PMID: 12414994 DOI: 10.1242/jcs.00093] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We showed previously that overexpression of the alpha subunit of G(z) or G(i2) suppresses nordihydroguaiaretic acid-induced Golgi disassembly. To determine whether the active form of Galpha is required to maintain the structure of the Golgi apparatus, we examined the effects of a series of Galpha GAPs, regulators of G protein signaling (RGS) proteins, on the Golgi structure. Expression of RGSZ1 or RGSZ2, both of which exhibit high selectivity for Galpha(z), markedly induced dispersal of the Golgi apparatus, whereas expression of RGS proteins that are rather selective for Galpha(q) or other Galpha(i) species did not. A mutated RGSZ1, which is deficient in the interaction with Galpha(z), did not induce Golgi disassembly. These results suggest that the active form of Galpha(z), but not Galpha(i2), is crucial for maintenance of the structure of the Golgi apparatus. Consistent with this idea, Golgi disruption also took place in cells transfected with a dominant-negative Galpha(z) mutant. Although previous studies showed that the expression of Galpha(z) is confined to neuronal cells and platelets, immunofluorescence and mRNA expression analyses revealed that it is also expressed, albeit at low levels, in non-neuronal cells, and is located in the Golgi apparatus. These results taken together suggest a general regulatory role for Galpha(z) in the control of the Golgi structure.
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Affiliation(s)
- Masami Nagahama
- School of Life Science, Tokyo University of Pharmacy and Life Science, Hachioji, Tokyo 192-0392, Japan
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44
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Abstract
We previously identified a specific activation-dependent interaction between the alpha subunit of the heterotrimeric G protein, G(z), and a regulator of Rap1 signaling, Rap1GAP (Meng, J., Glick, J. L., Polakis, P., and Casey, P. J. (1999) J. Biol. Chem. 274, 36663-36669). We now demonstrate that activated forms of Galpha(z) are able to recruit Rap1GAP from a cytosolic location to the membrane. Using PC12 cells as a model for neuronal differentiation, the influence of G(z) activation on Rap1-mediated cell differentiation was examined. Introduction of constitutively-activated Galpha(z) into PC12 cells markedly attenuated the differentiation process of these cells induced by a cAMP analogue. Treatment of PC12 cells expressing wild type Galpha(z) with a specific agonist to the alpha(2A)-adrenergic receptor also attenuated cAMP-induced PC12 cell differentiation, demonstrating that receptor-mediated activation of G(z) was also effective in this regard. Furthermore, activation of G(z) decreased the ability of the cAMP analogue to trigger both Rap1 and extracellular-regulated kinase (ERK) activation. Differentiation of PC12 cells induced by nerve growth factor (NGF) is also thought to be a Rap1-mediated process, and G(z) activation was found to attenuate this process as well. Rap1 activation, ERK phosphorylation, and PC12 cell differentation induced by NGF treatment were all significantly attenuated by either transfection of constitutively activated Galpha(z) or receptor-mediated G(z) activation. Based on these findings, a model is proposed in which activation of G(z) results in recruitment of Rap1GAP to the membrane where it can effectively down-regulate Rap1 signaling. The implications of these findings in regard to a possible role for G(z) in neuronal development are discussed.
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Affiliation(s)
- Jingwei Meng
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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Ikeda K, Kobayashi T, Kumanishi T, Yano R, Sora I, Niki H. Molecular mechanisms of analgesia induced by opioids and ethanol: is the GIRK channel one of the keys? Neurosci Res 2002; 44:121-131. [PMID: 12354627 DOI: 10.1016/s0168-0102(02)00094-9] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Opioids and ethanol have been used since ancient times for pain relief. Opioid signaling is mediated by various effectors, including G protein-activated inwardly rectifying potassium (GIRK) channels, adenylyl cyclases, voltage-dependent calcium channels, phospholipase Cbeta(PLCbeta), and mitogen-activated protein kinases, although it has been unclear which effector mediates the analgesic effects of opioids. Ethanol induces a variety of physiological phenomena via various proteins, including GIRK channels rather than via membrane lipids. GIRK channel activation by either G proteins or ethanol is impaired in weaver mutant mice. The mutant mice may therefore serve as a useful animal model for studying the role of GIRK channels in vivo. Reduced analgesia by using either opioids or ethanol in weaver mutant mice suggests that GIRK channels are important effectors in both opioid- and ethanol-induced analgesia. This hypothesis is supported by similar findings in GIRK2 knockout mice. Among the various effectors coupled with opioid receptors and various targets of ethanol, GIRK channels are the only molecules whose involvement in opioid- and ethanol-induced analgesia has been demonstrated in vivo. The GIRK channel is potentially one of the key molecules in furthering the understanding of the pain control system and in developing advanced analgesics with fewer adverse effects.
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Affiliation(s)
- Kazutaka Ikeda
- Department of Molecular Psychiatry, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya-ku, Tokyo 156-8585, Japan.
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Giaroni C, Zanetti E, Vanti A, Canciani L, Lecchini S, Frigo G. Sympathetic denervation-induced changes in G protein expression in enteric neurons of the guinea pig colon. Life Sci 2002; 71:1961-73. [PMID: 12175891 DOI: 10.1016/s0024-3205(02)01961-6] [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: 11/20/2022]
Abstract
Chronic sympathetic denervation entails subsensitivity to alpha(2)-adrenoceptor agonists and supersensitivity to kappa- and mu-opioid receptor agonists modulating cholinergic neurons in the guinea pig colon. A possible role for signal transduction G proteins in contributing to development of these sensitivity changes was investigated. Pertussis toxin (PTX), a blocker of the G(i/o)-type family of G proteins significantly reduced the inhibitory effects of UK14,304 (alpha(2)-adrenoceptor agonist), U69593 (kappa-opioid receptor agonist) and DAMGO (mu-opioid receptor agonist) on acetylcholine (ACh) overflow in preparations obtained from normal animals, but not in those obtained from sympathetically denervated animals. In this experimental condition, immunoblot analysis revealed reduced levels of G(alphao), G(alphai2), G(alphai3) and G(beta) in myenteric plexus synaptosomes. On reverse, synaptosomal levels of G(alphai1) and G(alphaz), a PTX-insensitive G-protein, increased after chronic ablation of the sympathetic pathways. These data suggest that changes in the function and expression of inhibitory G proteins coupled to alpha(2)-adrenoceptors, kappa- and mu-opioid receptors occur in the myenteric plexus of the guinea pig colon after chronic sympathetic denervation. The possibility that regulation of G proteins represents one of the biochemical mechanisms at the basis of the changes in sensitivity of enteric cholinergic neurons to alpha(2)-adrenoceptor, kappa- and mu-opioid receptor agonists is discussed.
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Affiliation(s)
- Cristina Giaroni
- Clinical and Applied Pharmacology Centre, Universities of Insubria and Pavia, via O. Rossi 9, I-21100 Varese, Italy
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Garzón J, Rodríguez-Díaz M, López-Fando A, García-España A, Sánchez-Blázquez P. Glycosylated phosducin-like protein long regulates opioid receptor function in mouse brain. Neuropharmacology 2002; 42:813-28. [PMID: 12015208 DOI: 10.1016/s0028-3908(02)00027-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Phosducin (Phd), a protein that in retina regulates rhodopsin desensitization by controlling the activity of Gt beta gamma-dependent G-protein-coupled receptor kinases (GRKs), is present in very low levels in the CNS of mammals. However, this tissue contains proteins of related sequence and function. This paper reports the presence of N-glycosylated phosducin-like protein long (PhLP(L)) in all structures of mouse CNS, mainly in synaptic plasma membranes and associated with G beta subunits and 14-3-3 proteins. To analyze the role PhLP(L) in opioid receptor desensitization, its expression was reduced by the use of antisense oligodeoxynucleotides (ODNs). The antinociception induced by morphine, [D-Ala(2), N-MePhe(4),Gly-ol(5)]-enkephalin (DAMGO), beta-endorphin, [D-Ala(2)]deltorphin II, [D-Pen(2,5)]-enkephalin (DPDPE) or clonidine in the tail-flick test was reduced in PhLP(L)-knock-down mice. A single intracerebroventricular (icv)-ED(80) analgesic dose of morphine gave rise to acute tolerance that lasted for 4 days, but which was prevented or reversed by icv-injection of myristoylated (myr(+)) G(i2)alpha subunits. PhLP(L) knock-down brought about a myr(+)-G(i2)alpha subunit-insensitive acute tolerance to morphine that was still present after 8 days. It also diminished the specific binding of (125)I-Tyr(27)-beta-endorphin-(1-31) (human) to mouse periaqueductal gray matter membranes. After being exposed to chronic morphine treatment, post-dependent mice required about 10 days for complete recovery of morphine antinociception. The impairment of PhLP(L) extended this period beyond 17 days. It is concluded that PhLP(L) knock-down facilitates desensitization and uncoupling of opioid receptors.
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Affiliation(s)
- J Garzón
- Neurofarmacología, Instituto Cajal, Consejo Superior de Investigaciones Científicas, Avd Doctor Arce, 37, E-28002 Madrid, Spain.
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Powell KL, Matthaei KI, Heydon K, Hendry IA. G(z alpha) deficient mice: enzyme levels in the autonomic nervous system, neuronal survival and effect of genetic background. Int J Dev Neurosci 2002; 20:39-46. [PMID: 12008073 DOI: 10.1016/s0736-5748(02)00002-3] [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: 11/27/2022] Open
Abstract
Our laboratory has generated a genetically mutant mouse in which the alpha subunit of the heterotrimeric GTP binding protein, G(z) has been made dysfunctional by homologous recombination to determine its in vivo function. These animals show a characteristic failure to thrive phenotype. G(z alpha) is expressed in a variety of nervous system tissues as well as in the adrenal medulla. We therefore examined the autonomic nervous system of the G(z alpha) deficient mouse by measuring the activity of tyrosine hydroxylase and choline acetyltransferase in the superior cervical ganglia, submaxillary gland and the adrenal medulla. Preliminary results using animals of mixed BALB/c and C57BL/6 strains gave inconsistent results. Further experiments demonstrated differences in the activity of tyrosine hydroxylase and choline acetyltransferase between BALB/c and C57BL/6 mouse strains. The analysis of the pure strains showed a reduction in the size and enzyme levels of the adrenal gland and submaxillary glands of the G(z alpha) deficient mouse suggesting a role for adrenal insufficiency and/or nutritional disorders for the failure to thrive phenotype. The survival of sympathetic and sensory neurons was also examined in the G(z alpha) deficient mouse and in the presence of pertussis toxin, sympathetic but not sensory neuronal survival in G(z alpha) deficient mice was significantly attenuated. This suggests that in vivo other pertussis toxin sensitive G proteins may be recruited to compensate for the loss of G(z alpha).
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Affiliation(s)
- Kim L Powell
- Developmental Neurobiology Group, Division of Neuroscience, John Curtin School of Medical Research, Australian National University, Box 334, Canberra, ACT 2601, Australia
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49
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Abstract
This paper is the twenty-third installment of the annual review of research concerning the opiate system. It summarizes papers published during 2000 that studied the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects, although stress-induced analgesia is included. The specific topics covered this year include stress; tolerance and dependence; learning, memory, and reward; eating and drinking; alcohol and other drugs of abuse; sexual activity, pregnancy, and development; mental illness and mood; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; gastrointestinal, renal, and hepatic function; cardiovascular responses; respiration and thermoregulation; and immunological responses.
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Affiliation(s)
- A L Vaccarino
- Department of Psychology, University of New Orleans, New Orleans, LA 70148, USA.
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50
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Abstract
A large variety of neurotransmitters, hormones, and chemokines regulate cellular functions via cell surface receptors that are coupled to guanine nucleotide-binding regulatory proteins (G proteins) belonging to the G(i) subfamily. All members of the G(i) subfamily, with the sole exception of G(z), are substrates for the pertussis toxin ADP-ribosyl transferase. G(z) also exhibits unique biochemical and regulatory properties. Initial portrayals of the cellular functions of G(z) bear high resemblance to those of other G(i) proteins both in terms of the receptors and effectors linked to G(z). However, recent discoveries have begun to insinuate a distinct role for G(z) in cellular communication. Functional interactions of the alpha subunit of G(z) (Galpha(z)) with the NKR-P1 receptor, Galpha(z)-specific regulator of G protein signaling, p21-activated kinase, G protein-regulated inducers of neurite outgrowth, and the Eya2 transcription cofactor have been demonstrated. These findings provide possible links for G(z) to participate in cellular development, survival, proliferation, differentiation and even apoptosis. In this review, we have drawn a sketch of a signaling network with G(z) as the centerpiece. The emerging picture is one that distinguishes G(z) from other members of the G(i) subfamily.
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Affiliation(s)
- M K Ho
- Department of Biochemistry and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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