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D'Souza MS, Seeley SL, Emerson N, Rose-Malkamaki MJ, Ho SP, Tsai YC, Kuo H, Huan CY, Rorabaugh BR. Attenuation of nicotine-induced rewarding and antidepressant-like effects in male and female mice lacking regulator of G-protein signaling 2. Pharmacol Biochem Behav 2022; 213:173338. [PMID: 35038444 DOI: 10.1016/j.pbb.2022.173338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 01/07/2022] [Accepted: 01/10/2022] [Indexed: 11/28/2022]
Abstract
Nicotine-induced rewarding and mood altering effects contribute to the continued use of nicotine and the subsequent development of nicotine dependence. The goal of this study was to assess the role of two specific regulators of G-protein signaling (RGS) proteins namely RGS2 and RGS4 in the above described effects of nicotine. Male and female mice lacking either RGS2 (RGS2 KO) or RGS4 (RGS4 KO), and their respective wildtype (WT) littermates were used in this study. The rewarding effects of nicotine (0.5 mg/kg, base; s.c.) were assessed using the conditioned place preference model. Nicotine-induced anxiolytic-like (0.1 mg/kg, base; i.p.) and antidepressant-like (1 mg/kg, base; i.p.) effects were assessed using the elevated plus maze and tail suspension test, respectively. We also assessed effects of nicotine (0, 0.05, 0.1 & 0.5 mg/kg, base; s.c.) on spontaneous locomotor activity. Nicotine-induced rewarding and antidepressant-like effects were observed in both male and female RGS2 WT mice, but not in mice lacking RGS2 compared to respective controls. In contrast, nicotine-induced rewarding and antidepressant-like effects were observed in both male and female mice lacking RGS4 and their WT littermates. Interestingly, deletion of RGS4 facilitated antidepressant-like effect of nicotine in male, but not female mice compared to respective WT littermates. Nicotine-induced anxiolytic-like effect was not influenced by deletion of either RGS2 or RGS4, irrespective of sex. Nicotine (0.5 mg/kg) decreased locomotor activity in both WT and KO mice compared to respective saline, irrespective of genotype and sex. Taken together, these data provide evidence that RGS2, but not RGS4, plays a role in mediating the rewarding and antidepressant-like effects of nicotine. Further research is required to explore the role of RGS2 after chronic exposure to nicotine.
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Affiliation(s)
- Manoranjan S D'Souza
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States.
| | - Sarah L Seeley
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Nate Emerson
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Madison J Rose-Malkamaki
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Sheng-Ping Ho
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Yi-Chih Tsai
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Henry Kuo
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Ching-Yu Huan
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States
| | - Boyd R Rorabaugh
- Department of Pharmaceutical Sciences, School of Pharmacy, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, United States
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2
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Chrissobolis S, Luu AN, Waldschmidt RA, Yoakum ME, D'Souza MS. Targeting the renin angiotensin system for the treatment of anxiety and depression. Pharmacol Biochem Behav 2020; 199:173063. [PMID: 33115635 DOI: 10.1016/j.pbb.2020.173063] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/13/2020] [Accepted: 10/22/2020] [Indexed: 12/27/2022]
Abstract
Emotional disorders like anxiety and depression are responsible for considerable morbidity and mortality all over the world. Several antidepressant and anxiolytic medications are available for the treatment of anxiety and depression. However, a significant number of patients either do not respond to these medications or respond inadequately. Hence, there is a need to identify novel targets for the treatment of anxiety and depression. In this review we focus on the renin angiotensin system (RAS) as a potential target for the treatment of these disorders. We review work that has evaluated the effects of various compounds targeting the RAS on anxiety- and depression-like behaviors. Further, we suggest future work that must be carried out to fully exploit the RAS for the treatment of anxiety and depression. The RAS provides an attractive target for both the identification of novel anxiolytic and antidepressant medications and/or for enhancing the efficacy of currently available medications used for the treatment of anxiety and depression.
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Affiliation(s)
- Sophocles Chrissobolis
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States of America
| | - Anh N Luu
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States of America
| | - Ryan A Waldschmidt
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States of America
| | - Madison E Yoakum
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States of America
| | - Manoranjan S D'Souza
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, 525 S Main Street, Ada, OH 45810, United States of America.
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3
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Jia H, Song G, Werth EG, Walley JW, Hicks LM, Jones AM. Receptor-Like Kinase Phosphorylation of Arabidopsis Heterotrimeric G-Protein Gα -Subunit AtGPA1. Proteomics 2019; 19:e1900265. [PMID: 31693794 PMCID: PMC7014827 DOI: 10.1002/pmic.201900265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/04/2019] [Indexed: 01/07/2023]
Abstract
As molecular on-off switches, heterotrimeric G protein complexes, comprised of a Gα subunit and an obligate Gβγ dimer, transmit extracellular signals received by G protein-coupled receptors (GPCRs) to cytoplasmic targets that respond to biotic and abiotic stimuli. Signal transduction is modulated by phosphorylation of GPCRs and G protein complexes. In Arabidopsis thaliana, the Gα subunit AtGPA1 is phosphorylated by the receptor-like kinase (RLK) BRI1-associated Kinase 1 (BAK1), but the extent that other RLKs phosphorylates AtGPA1 is unknown. Twenty-two trans-phosphorylation sites on AtGPA1 are mapped by 12 RLKs hypothesized to act in the Arabidopsis G protein signaling pathway. Cis-phosphorylation sites are also identified on these RLKs, some newly shown to be dual specific kinases. Multiple sites are present in the core AtGPA1 functional units, including pSer52 and/or pThr53 of the conserved P-loop that directly binds nucleotide/phosphate, pThr164, and pSer175 from αE helix in the intramolecular domain interface for nucleotide exchange and GTP hydrolysis, and pThr193 and/or pThr194 in Switch I (SwI) that coordinates nucleotide exchange and protein partner binding. Several AtGPA1 S/T phosphorylation sites are potentially nucleotide-dependent phosphorylation patterns, such as Ser52/Thr53 in the P-loop and Thr193 and/or Thr194 in SwI.
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Affiliation(s)
- Haiyan Jia
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Gaoyuan Song
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
| | - Emily G Werth
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Justin W Walley
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, 50011, USA
| | - Leslie M Hicks
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Alan M Jones
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
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Özen I, Roth M, Barbariga M, Gaceb A, Deierborg T, Genové G, Paul G. Loss of Regulator of G-Protein Signaling 5 Leads to Neurovascular Protection in Stroke. Stroke 2019; 49:2182-2190. [PMID: 30354999 PMCID: PMC6116795 DOI: 10.1161/strokeaha.118.020124] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background and Purpose- In ischemic stroke, breakdown of the blood-brain barrier (BBB) aggravates brain damage. Pericyte detachment contributes to BBB disruption and neurovascular dysfunction, but little is known about its regulation in stroke. Here, we investigated how loss of RGS5 (regulator of G protein signaling 5) in pericytes affects BBB breakdown in stroke and its consequences. Method- We used RGS5 knockout and control mice and applied a permanent middle cerebral occlusion model. We analyzed pericyte numbers, phenotype, and vessel morphology using immunohistochemistry and confocal microscopy. We investigated BBB breakdown by measuring endothelial coverage, tight junctions, and AQP4 (aquaporin 4) in addition to BBB permeability (fluorescent-conjugated dextran extravasation). Tissue hypoxia was assessed with pimonidazole hydrochloride and neuronal death quantified with the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Results- We demonstrate that loss of RGS5 increases pericyte numbers and their endothelial coverage, which is associated with higher capillary density and length, and significantly less BBB damage after stroke. Loss of RGS5 in pericytes results in reduced vascular leakage and preserved tight junctions and AQP4, decreased cerebral hypoxia, and partial neuronal protection in the infarct area. Conclusions- Our findings show that loss of RGS5 affects pericyte-related BBB preservation in stroke and identifies RGS5 as an important target for neurovascular protection.
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Affiliation(s)
- Ilknur Özen
- From the Translational Neurology Group, Department of Clinical Science (I.O., M.R., M.B., A.G., G.P.)
| | - Michaela Roth
- From the Translational Neurology Group, Department of Clinical Science (I.O., M.R., M.B., A.G., G.P.)
| | - Marco Barbariga
- From the Translational Neurology Group, Department of Clinical Science (I.O., M.R., M.B., A.G., G.P.)
| | - Abderahim Gaceb
- From the Translational Neurology Group, Department of Clinical Science (I.O., M.R., M.B., A.G., G.P.)
| | - Tomas Deierborg
- Experimental Neuroinflammation Laboratory, Department of Experimental Medical Sciences (T.D.)
| | - Guillem Genové
- Lund University, Sweden; Department of Medicine, Integrated Cardio Metabolic Center, Karolinska Institute, Huddinge, Sweden (G.G.)
| | - Gesine Paul
- From the Translational Neurology Group, Department of Clinical Science (I.O., M.R., M.B., A.G., G.P.).,Wallenberg Centre for Molecular Medicine (G.P.).,Department of Neurology, Scania University Hospital, Lund, Sweden (G.P.)
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Israeli R, Asli A, Avital-Shacham M, Kosloff M. RGS6 and RGS7 Discriminate between the Highly Similar Gα i and Gα o Proteins Using a Two-Tiered Specificity Strategy. J Mol Biol 2019; 431:3302-3311. [PMID: 31153905 DOI: 10.1016/j.jmb.2019.05.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 05/12/2019] [Accepted: 05/23/2019] [Indexed: 11/15/2022]
Abstract
RGS6 and RGS7 are regulators of G protein signaling (RGS) proteins that inactivate heterotrimeric (αβγ) G proteins and mediate diverse biological functions, such as cardiac and neuronal signaling. Uniquely, both RGS6 and RGS7 can discriminate between Gαo and Gαi1-two similar Gα subunits that belong to the same Gi sub-family. Here, we show that the isolated RGS domains of RGS6 and RGS7 are sufficient to achieve this specificity. We identified three specific RGS6/7 "disruptor residues" that can attenuate RGS interactions toward Gα subunits and demonstrated that their insertion into a representative high-activity RGS causes a significant, yet non-specific, reduction in activity. We further identified a unique "modulatory" residue that bypasses this negative effect, specifically toward Gαo. Hence, the exquisite specificity of RGS6 and RGS7 toward closely related Gα subunits is achieved via a two-tier specificity system, whereby a Gα-specific modulatory motif overrides the inhibitory effect of non-specific disruptor residues. Our findings expand the understanding of the molecular toolkit used by the RGS family to achieve specific interactions with selected Gα subunits-emphasizing the functional importance of the RGS domain in determining the activity and selectivity of RGS R7 sub-family members toward particular Gα subunits.
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Affiliation(s)
- Ran Israeli
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Ali Asli
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Meirav Avital-Shacham
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel
| | - Mickey Kosloff
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa 3498838, Israel.
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Rorabaugh BR, Sprague L, Norman H, Seeley SL, D'Souza MS. Regulator of G protein signaling 2 differentially regulates nicotine-induced anxiolytic- and antidepressant-like effects in mice. Eur J Neurosci 2018; 48:2110-2117. [PMID: 30103281 DOI: 10.1111/ejn.14100] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 07/19/2018] [Accepted: 07/24/2018] [Indexed: 11/27/2022]
Abstract
This study assessed the role of regulator of G protein signaling 2 (RGS2) in nicotine-induced anxiolytic- and antidepressant-like effects using RGS2 wildtype (WT) and RGS2 knockout (KO) mice. RGS2 negatively regulates monoaminergic neurotransmission, which is implicated in the pathology of anxiety and depression. We hypothesized that deletion of RGS2 would enhance nicotine-induced anxiolytic- and antidepressant-like effects, which were assessed using the elevated plus maze and tail suspension tests, respectively. Anxiolytic-like effects were observed in both RGS2 WT and KO mice after administration of low dose of nicotine (0.05 mg/kg, base) compared to respective saline controls. Additionally, administration of nicotine (0.1 mg/kg, base) compared to saline resulted in anxiolytic-like effects in RGS2 KO mice, but not RGS2 WT mice, suggesting genetic deletion of RGS2 facilitated anxiolytic-like effects of nicotine. Administration of nicotine (0.5 and 1 mg/kg, base) compared to saline resulted in antidepressant-like effects in RGS2 WT mice. Antidepressant-like effects were observed in RGS2 KO mice only at the highest tested dose of nicotine (1 mg/kg, base) compared to saline controls, suggesting that genetic deletion of RGS2 decreased sensitivity to antidepressant-like effects of nicotine. Together, the data suggest that RGS2 differentially regulated nicotine-induced affective behavioral responses. These data suggest that individuals with RGS2 polymorphisms may experience differential affective responses to tobacco smoking, which may make them vulnerable to developing nicotine addiction.
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Affiliation(s)
- Boyd R Rorabaugh
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio
| | - Lisanne Sprague
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio
| | - Haval Norman
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio
| | - Sarah L Seeley
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio
| | - Manoranjan S D'Souza
- Department of Pharmaceutical and Biomedical Sciences, The Raabe College of Pharmacy, Ohio Northern University, Ada, Ohio
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7
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Doupnik CA. RGS Redundancy and Implications in GPCR-GIRK Signaling. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:87-116. [PMID: 26422983 DOI: 10.1016/bs.irn.2015.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Regulators of G protein signaling (RGS proteins) are key components of GPCR complexes, interacting directly with G protein α-subunits to enhance their intrinsic GTPase activity. The functional consequence is an accelerated termination of G protein effectors including certain ion channels. RGS proteins have a profound impact on the membrane-delimited gating behavior of G-protein-activated inwardly rectifying K(+) (GIRK) channels as demonstrated in reconstitution assays and recent RGS knockout mice studies. Akin to GPCRs and G protein αβγ subunits, multiple RGS isoforms are expressed within single GIRK-expressing neurons, suggesting functional redundancy and/or specificity in GPCR-GIRK channel signaling. The extent and impact of RGS redundancy in neuronal GPCR-GIRK channel signaling is currently not fully appreciated; however, recent studies from RGS knockout mice are providing important new clues on the impact of individual endogenous RGS proteins and the extent of RGS functional redundancy. Incorporating "tools" such as engineered RGS-resistant Gαi/o subunits provide an important assessment method for determining the impact of all endogenous RGS proteins on a given GPCR response and an accounting benchmark to assess the impact of individual RGS knockouts on overall RGS redundancy within a given neuron. Elucidating the degree of regulation attributable to specific RGS proteins in GIRK channel function will aid in the assessment of individual RGS proteins as viable therapeutic targets in epilepsy, ataxia's, memory disorders, and a growing list of neurological disorders.
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Affiliation(s)
- Craig A Doupnik
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida, USA.
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Brown RW, Peterson DJ. Applications of the Neonatal Quinpirole Model to Psychosis and Convergence upon the Dopamine D 2 Receptor. Curr Top Behav Neurosci 2015; 29:387-402. [PMID: 26472551 DOI: 10.1007/7854_2015_394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This mini review focuses on the importance of the dopamine D2-like receptor family and its importance in psychosis. Past findings from this laboratory along with collaborators have been that neonatal quinpirole (a dopamine D2-like receptor agonist) results in increases in dopamine D2 receptor sensitivity that persists throughout the animal's lifetime. Findings from this model have been shown to have particular application and validity to schizophrenia, but may have broader implications toward other psychoses, which is reviewed in the present manuscript. In the present review, we also highlight other models of psychoses that have been centered on the subchronic administration of quinpirole to rats in order to model certain psychoses, which has uncovered some interesting and valid behavioral findings. This review highlights the importance of the combination of behavioral findings and neurobiological mechanisms focusing on neural plasticity in discovering underlying pathologies in these disorders that may lead to treatment discoveries, as well as the value of animal models across all psychoses.
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Affiliation(s)
- Russell W Brown
- Department of Biomedical Science, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN, 37614-1702, USA.
| | - Daniel J Peterson
- Department of Psychology, East Tennessee State University, Johnson City, TN, 37614-1702, USA
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Vashisth H, Storaska AJ, Neubig RR, Brooks CL. Conformational dynamics of a regulator of G-protein signaling protein reveals a mechanism of allosteric inhibition by a small molecule. ACS Chem Biol 2013; 8:2778-84. [PMID: 24093330 DOI: 10.1021/cb400568g] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Regulators of G protein signaling (RGS) proteins are key players in regulating signaling via G protein-coupled receptors. RGS proteins directly bind to the Gα-subunits of activated heterotrimeric G-proteins, and accelerate the rate of GTP hydrolysis, thereby rapidly deactivating G-proteins. Using atomistic simulations and NMR spectroscopy, we have studied in molecular detail the mechanism of action of CCG-50014, a potent small molecule inhibitor of RGS4 that covalently binds to cysteine residues on RGS4. We apply temperature-accelerated molecular dynamics (TAMD) to carry out enhanced conformational sampling of apo RGS4 structures, and consistently find that the α5-α6 helix pair of RGS4 can spontaneously span open-like conformations, allowing binding of CCG-50014 to the buried side-chain of Cys95. Both NMR experiments and MD simulations reveal chemical shift perturbations in residues in the vicinity of inhibitor binding site as well as in the RGS4-Gα binding interface. Consistent with a loss of G-protein binding, GAP activity, and allosteric mechanism of action of CCG-50014, our simulations of the RGS4-Gα complex in the presence of inhibitor suggest a relatively unstable protein-protein interaction. These results have potential implications for understanding how the conformational dynamics among RGS proteins may play a key role in the sensitivity of inhibitors.
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Affiliation(s)
- Harish Vashisth
- Department
of Chemical Engineering, University of New Hampshire, Durham, New Hampshire 03824, United States of America
| | - Andrew J. Storaska
- Department
of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, United States of America
| | - Richard R. Neubig
- Department
of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, United States of America
| | - Charles L. Brooks
- Department
of Chemistry and Biophysics Program, University of Michigan, Ann Arbor, Michigan 48109, United States of America
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Brown RW, Maple AM, Perna MK, Sheppard AB, Cope ZA, Kostrzewa RM. Schizophrenia and Substance Abuse Comorbidity: Nicotine Addiction and the Neonatal Quinpirole Model. Dev Neurosci 2012; 34:140-51. [DOI: 10.1159/000338830] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 04/12/2012] [Indexed: 01/06/2023] Open
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Mackie DI, Roman DL. Development of a novel high-throughput screen and identification of small-molecule inhibitors of the Gα-RGS17 protein-protein interaction using AlphaScreen. ACTA ACUST UNITED AC 2011; 16:869-77. [PMID: 21680864 DOI: 10.1177/1087057111410427] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In this study, the authors used AlphaScreen technology to develop a high-throughput screening method for interrogating small-molecule libraries for inhibitors of the Gα(o)-RGS17 interaction. RGS17 is implicated in the growth, proliferation, metastasis, and the migration of prostate and lung cancers. RGS17 is upregulated in lung and prostate tumors up to a 13-fold increase over patient-matched normal tissues. Studies show RGS17 knockdown inhibits colony formation and decreases tumorigenesis in nude mice. The screen in this study uses a measurement of the Gα(o)-RGS17 protein-protein interaction, with an excellent Z score exceeding 0.73, a signal-to-noise ratio >70, and a screening time of 1100 compounds per hour. The authors screened the NCI Diversity Set II and determined 35 initial hits, of which 16 were confirmed after screening against controls. The 16 compounds exhibited IC(50) <10 µM in dose-response experiments. Four exhibited IC(50) values <6 µM while inhibiting the Gα(o)-RGS17 interaction >50% when compared to a biotinylated glutathione-S-transferase control. This report describes the first high-throughput screen for RGS17 inhibitors, as well as a novel paradigm adaptable to many other RGS proteins, which are emerging as attractive drug targets for modulating G-protein-coupled receptor signaling.
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Affiliation(s)
- Duncan I Mackie
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, 115 South Grand Avenue, Iowa City, IA 52242, USA
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12
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Abstract
Drug addiction is marked by continued drug-seeking behavior despite deleterious consequences and a heightened propensity to relapse not withstanding long, drug-free periods. The enduring nature of addiction has been hypothesized to arise from perturbations in intracellular signaling, gene expression, and brain circuitry induced by substance abuse. Ameliorating some of these aberrations should abate behavioral and neurochemical markers associated with an 'addiction phenotype'. This review summarizes data showing that protein expression and signaling through the nonreceptor activator of G-protein signaling 3 (AGS3) are altered by commonly abused substances in rat and in in-vitro addiction models. AGS3 structure and function are unrelated to the more broadly studied regulator of G-protein signaling family. Thus, the unique role of AGS3 is the focus of this review. Intriguingly, AGS3 protein changes persist into drug abstinence. Accordingly, studies probing the role of AGS3 in the neurochemistry of drug-seeking behavior and relapse are studied in detail. To illuminate this study, AGS3 structure, cellular localization, and function are covered so that an idealized AGS3-targeted pharmacotherapy can be proposed.
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Affiliation(s)
- Michael Scott Bowers
- Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA.
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Icaza EE, Huang X, Fu Y, Neubig RR, Baghdoyan HA, Lydic R. Isoflurane-induced changes in righting response and breathing are modulated by RGS proteins. Anesth Analg 2009; 109:1500-5. [PMID: 19843788 DOI: 10.1213/ane.0b013e3181ba7815] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Recent evidence suggests that G protein-coupled receptors, especially those linked to G(alpha)(i), contribute to the mechanisms of anesthetic action. Regulator of G protein signaling (RGS) proteins bind to activated G(alpha)(i) and inhibit signal transduction. Genomic knock-in mice with an RGS-insensitive G(alpha)(i2) G184S (G(alpha)(i2) GS) allele exhibit enhanced G(alpha)(i2) signaling and provide a novel approach for investigating the role of G(alpha)(i2) signaling and RGS proteins in general anesthesia. METHODS We anesthetized homozygous G(alpha)(i2) GS/GS and wild-type (WT) mice with isoflurane and quantified time (in seconds) to loss and resumption of righting response. During recovery from isoflurane anesthesia, breathing was quantified in a plethysmography chamber for both lines of mice. RESULTS G(alpha)(i2) GS/GS mice required significantly less time for loss of righting and significantly more time for resumption of righting than WT mice. During recovery from isoflurane anesthesia, G(alpha)(i2) GS/GS mice exhibited significantly greater respiratory depression. Poincaré analyses show that GS/GS mice have diminished respiratory variability compared with WT mice. CONCLUSION Modulation of G(alpha)(i2) signaling by RGS proteins alters loss and resumption of wakefulness and state-dependent changes in breathing.
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Affiliation(s)
- Eduardo E Icaza
- Departments of Anesthesiology, University of Michigan, Ann Arbor, Michigan 48109-5615, USA
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McCoy KL, Hepler JR. Regulators of G protein signaling proteins as central components of G protein-coupled receptor signaling complexes. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 86:49-74. [PMID: 20374713 DOI: 10.1016/s1877-1173(09)86003-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The regulators of G protein signaling (RGS) proteins bind directly to G protein alpha (Gα) subunits to regulate the signaling functions of Gα and their linked G protein-coupled receptors (GPCRs). Recent studies indicate that RGS proteins also interact with GPCRs, not just G proteins, to form preferred functional pairs. Interactions between GPCRs and RGS proteins may be direct or indirect (via a linker protein) and are dictated by the receptors, rather than the linked G proteins. Emerging models suggest that GPCRs serve as platforms for assembling an overlapping and distinct constellation of signaling proteins that perform receptor-specific signaling tasks. Compelling evidence now indicates that RGS proteins are central components of these GPCR signaling complexes. This review will outline recent discoveries of GPCR/RGS pairs as well as new data in support of the idea that GPCRs serve as platforms for the formation of multiprotein signaling complexes.
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Affiliation(s)
- Kelly L McCoy
- Department of Pharmacology, G205 Rollins Research Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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15
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Roman DL, Ota S, Neubig RR. Polyplexed flow cytometry protein interaction assay: a novel high-throughput screening paradigm for RGS protein inhibitors. JOURNAL OF BIOMOLECULAR SCREENING 2009; 14:610-9. [PMID: 19531661 PMCID: PMC2908316 DOI: 10.1177/1087057109336590] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Intracellular signaling cascades are a series of regulated protein-protein interactions that may provide a number of targets for potential drug discovery. Here, the authors examine the interaction of regulators of G-protein signaling (RGS) proteins with the G-protein Galphao, using a flow cytometry protein interaction assay (FCPIA). FCPIA accurately measures nanomolar binding constants of this protein-protein interaction and has been used in high-throughput screening. This report focuses on 5 RGS proteins (4, 6, 7, 8, and 16). To increase the content of screens, the authors assessed high-throughput screening of these RGS proteins in multiplex, by establishing binding constants of each RGS with Galphao in isolation, and then in a multiplex format with 5 RGS proteins present. To use this methodology as a higher-content multiplex protein-protein interaction screen, they established Z-factor values for RGS proteins in multiplex of 0.73 to 0.92, indicating this method is suitable for screening using FCPIA. To increase throughput, they also compressed a set of 8000 compounds by combining 4 compounds in a single assay well. Subsequent deconvolution of the compounds mixtures verified the identification of active compounds at specific RGS targets in their mixtures using the polyplexed FCPIA method.
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Affiliation(s)
- David L Roman
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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16
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Small molecule protein-protein interaction inhibitors as CNS therapeutic agents: current progress and future hurdles. Neuropsychopharmacology 2009; 34:126-41. [PMID: 18800065 DOI: 10.1038/npp.2008.151] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Protein-protein interactions are a crucial element in cellular function. The wealth of information currently available on intracellular-signaling pathways has led many to appreciate the untapped pool of potential drug targets that reside downstream of the commonly targeted receptors. Over the last two decades, there has been significant interest in developing therapeutics and chemical probes that inhibit specific protein-protein interactions. Although it has been a challenge to develop small molecules that are capable of occluding the large, often relatively featureless protein-protein interaction interface, there are increasing numbers of examples of small molecules that function in this manner with reasonable potency. This article will highlight the current progress in the development of small molecule protein-protein interaction inhibitors that have applications in the treatment or study of central nervous system function and disease. In particular, we will focus upon recent work towards developing small molecule inhibitors of amyloid-beta and alpha-synuclein aggregation, inhibitors of critical components of G-protein-signaling pathways, and PDZ domain inhibitors.
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17
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Jayaraman M, Zhou H, Jia L, Cain MD, Blumer KJ. R9AP and R7BP: traffic cops for the RGS7 family in phototransduction and neuronal GPCR signaling. Trends Pharmacol Sci 2008; 30:17-24. [PMID: 19042037 DOI: 10.1016/j.tips.2008.10.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 10/07/2008] [Accepted: 10/09/2008] [Indexed: 10/21/2022]
Abstract
RGS (regulator of G protein signaling) proteins have emerged as crucial regulators, effectors and integrators in G-protein-coupled receptor (GPCR) signaling networks. Many RGS proteins accelerate GTP hydrolysis by Galpha subunits, thereby regulating G protein activity, whereas certain RGS proteins also transduce Galpha signals to downstream targets. Particularly intriguing are members of the RGS7 (R7) family (RGS6, RGS7, RGS9 and RGS11), which heterodimerize with Gbeta5. In Caenorhabditis elegans, R7-Gbeta5 heterodimers regulate synaptic transmission, anesthetic action and behavior. In vertebrates, they regulate vision, postnatal development, working memory and the action of psychostimulants or morphine. Here we highlight R9AP and R7BP, a related pair of recently identified SNARE-like R7-family binding proteins, which regulate intracellular trafficking, expression and function of R7-Gbeta5 heterodimers in retina and brain. Emerging understanding of R7BP and R9AP promises to provide new insights into neuronal GPCR signaling mechanisms relevant to the causes and treatment of neurological disorders.
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Affiliation(s)
- Muralidharan Jayaraman
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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18
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Roof RA, Sobczyk-Kojiro K, Turbiak AJ, Roman DL, Pogozheva ID, Blazer LL, Neubig RR, Mosberg HI. Novel peptide ligands of RGS4 from a focused one-bead, one-compound library. Chem Biol Drug Des 2008; 72:111-9. [PMID: 18637987 DOI: 10.1111/j.1747-0285.2008.00687.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Regulators of G protein signaling accelerate GTP hydrolysis by G alpha subunits and profoundly inhibit signaling by G protein-coupled receptors. The distinct expression patterns and pathophysiologic regulation of regulators of G protein signaling proteins suggest that inhibitors may have therapeutic potential. We previously reported the design, mechanistic evaluation, and structure-activity relationships of a disulfide-containing cyclic peptide inhibitor of RGS4, YJ34 (Ac-Val-Lys-c[Cys-Thr-Gly-Ile-Cys]-Glu-NH(2), S-S) (Roof et al., Chem Biol Drug Des, 67, 2006, 266). Using a focused one-bead, one-compound peptide library that contains features known to be necessary for the activity of YJ34, we now identify peptides that bind to RGS4. Six peptides showed confirmed binding to RGS4 by flow cytometry. Two analogs of peptide 2 (Gly-Thr-c[Cys-Phe-Gly-Thr-Cys]-Trp-NH(2), S-S with a free or acetylated N-terminus) inhibited RGS4-stimulated G alpha(o) GTPase activity at 25-50 microM. They selectively inhibit RGS4 but not RGS7, RGS16, and RGS19. Their inhibition of RGS4 does not depend on cysteine-modification of RGS4, as they do not lose activity when all cysteines are removed from RGS4. Peptide 2 has been modeled to fit in the same binding pocket predicted for YJ34 but in the reverse orientation.
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Affiliation(s)
- Rebecca A Roof
- Department of Pharmacology, University of Michigan, 1301 MSRB III/SPC5632, Ann Arbor, MI 48103, USA
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19
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Pei J, Dishinger JF, Roman DL, Rungwanitcha C, Neubig RR, Kennedy RT. Microfabricated channel array electrophoresis for characterization and screening of enzymes using RGS-G protein interactions as a model system. Anal Chem 2008; 80:5225-31. [PMID: 18465881 DOI: 10.1021/ac800553g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A microfluidic chip consisting of parallel channels designed for rapid electrophoretic enzyme assays was developed. Radial arrangement of channels and a common waste channel allowed chips with 16 and 36 electrophoresis units to be fabricated on a 7.62 x 7.62 cm(2) glass substrate. Fluorescence detection was achieved using a Xe arc lamp source and commercial charge-coupled device (CCD) camera to image migrating analyte zones in individual channels. Chip performance was evaluated by performing electrophoretic assays for G protein GTPase activity on chip using BODIPY-GTP as enzyme substrate. A 16-channel design proved to be useful in extracting kinetic information by allowing serial electrophoretic assays from 16 different enzyme reaction mixtures at 20 s intervals in parallel. This system was used to rapidly determine enzyme concentrations, optimal enzymatic reaction conditions, and Michaelis-Menten constants. A chip with 36 channels was used for screening for modulators of the G protein-RGS protein interaction by assaying the amount of product formed in enzyme reaction mixtures that contained test compounds. Thirty-six electrophoretic assays were performed in 30 s suggesting the potential throughput up to 4320 assays/h with appropriate sample handling procedures. Both designs showed excellent reproducibility of peak migration time and peak area. Relative standard deviations of normalized peak area of enzymatic product BODIPY-GDP were 5% and 11%, respectively, in the 16- and 36-channel designs.
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Affiliation(s)
- Jian Pei
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA
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20
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Regulation of heterotrimeric G protein signaling in airway smooth muscle. Ann Am Thorac Soc 2008; 5:47-57. [PMID: 18094084 DOI: 10.1513/pats.200705-054vs] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G proteins transduce signals from G protein-coupled receptors to regulate numerous signaling events and functions in airway smooth muscle (ASM). In this article, we detail the function and regulation of heterotrimeric G protein signaling in ASM. We further discuss recent advances in the development of experimental tools in the study of G protein signaling, and speculate how these tools might be used in therapeutic strategies that seek to mitigate bronchospasm and airway remodeling that occur in obstructive airway disease.
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21
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Ehlert FJ. On the analysis of ligand-directed signaling at G protein-coupled receptors. Naunyn Schmiedebergs Arch Pharmacol 2008; 377:549-77. [PMID: 18253722 DOI: 10.1007/s00210-008-0260-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2007] [Accepted: 01/09/2008] [Indexed: 12/01/2022]
Abstract
The phenomenon of "ligand-directed signaling" is often considered to be inconsistent with the traditional receptor theory. In this review, I show how the mathematics of the receptor theory can be used to measure the observed affinity and relative efficacy of protean ligands at G protein-coupled receptors. The basis of this analysis rests on the assumption that the fraction of agonist bound in the form of the active receptor-G protein-guanine nucleotide complex is the biochemical equivalent of the pharmacological stimulus. Consequently, this stimulus function is analogous to the current response of a ligand-gated ion channel. Because guanosine triphosphate (GTP) greatly inhibits the formation of the active quaternary complex, even the most efficacious agonists probably only elicit partial receptor activation, and it seems likely that the ceiling of 100% receptor activation is not reached in the intact cell with high intracellular concentrations of GTP. Under these conditions, the maximum of the stimulus function is proportional to the ratio of microscopic affinity constants of the agonist for ground and active states. Ligand-directed signaling depends on the existence of different active states of the receptor with different selectivities for different G proteins or other effectors. This phenomenon can be characterized using classic pharmacological methods. Although not widely appreciated, it is possible to estimate the product of observed affinity and intrinsic efficacy expressed relative to that of another agonist (intrinsic relative activity) through the analysis of the concentration-response curves. No other information is required. This approach should be useful in quantifying agonist activity and in converting the two disparate parameters of potency and maximal response into a single parameter dependent only on the agonist-receptor-effector complex.
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Affiliation(s)
- Frederick J Ehlert
- Department of Pharmacology, School of Medicine, University of California, Irvine, CA 92697, USA.
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22
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Maple AM, Perna MK, Parlaman JP, Stanwood GD, Brown RW. Ontogenetic quinpirole treatment produces long-lasting decreases in the expression of Rgs9, but increases Rgs17 in the striatum, nucleus accumbens and frontal cortex. Eur J Neurosci 2007; 26:2532-8. [DOI: 10.1111/j.1460-9568.2007.05860.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Jameson EE, Pei J, Wade SM, Neubig RR, Milligan G, Kennedy RT. Capillary electrophoresis assay for G protein-coupled receptor-mediated GTPase activity. Anal Chem 2007; 79:1158-63. [PMID: 17263349 DOI: 10.1021/ac061099g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe a capillary electrophoresis (CE) assay to detect G protein-coupled receptor (GPCR)-stimulated G protein GTPase activity in cell membranes expressing alpha2A adrenoreceptor-Galphao1 wild-type (wt) or C351I mutant fusion proteins using a fluorescent, hydrolyzable GTP analogue. As no change in total fluorescence is observed by conversion of substrate to product, CE is used to separate the fluorescent substrate (*GTP) from the fluorescent product (*GDP). Using the assay, the alpha2a adrenoceptor agonist UK14,304 was shown to simulate specific production of *GDP in membranes from HEK293T cells expressing receptor-G protein fusion to 525% of basal levels with an EC50 of 0.48 +/- 0.20 microM. The EC50 increased to 9.4 +/- 5 muM with addition of the antagonist yohimbine. Nucleotide hydrolysis was increased further over agonist-stimulated levels with addition of the in vivo modulator protein RGS (regulator of G protein signaling). It is envisioned that this technique could be used for screening for novel GPCR ligands or other G protein signaling modifiers.
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Affiliation(s)
- Emily E Jameson
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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24
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Kim SD, Sung HJ, Park SK, Kim TW, Park SC, Kim SK, Cho JY, Rhee MH. The expression patterns of RGS transcripts in platelets. Platelets 2007; 17:493-7. [PMID: 17074726 DOI: 10.1080/09537100600758123] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Regulators of G protein signalling (RGS) are involved in the negative regulation of cell activation processes and are involved in the pathophysiology of cardiovascular diseases. To get some further evidence for a role of RGS proteins in platelets, we determined the expression profile of RGS-specific mRNA in rat platelets using reverse transcription-polymerase chain reaction (RT-PCR) with a poly dT18 primer and transcript-specific primers. We found that RGS2, RGS3, RGS5, RGS6, RGS10, RGS14, RGS16 and RGS18, Leukemia-associated Rho-GEF factor (LARG), and Galpha interacting protein (GAIP) were differentially expressed in platelets. The highest expression rate was found for RGS18 (about 1.3 fold when compared to GAPDH), followed by LARG, RGS6, RGS10 and RGS16 (0.7 to 0.95), whereas expression rates for RGS2, RGS3, RGS5, RGS14, and GAIP were in a range of 0.1 to 0.3. Our results suggest that G-protein-coupled receptor-mediated signalling in platelet may be regulated mainly by RGS 18, 16, 10, 6, and LARG.
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Affiliation(s)
- Sung Dae Kim
- Laboratory of Veterinary Physiology & Signalling, College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, Republic of Korea
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25
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Roman DL, Talbot JN, Roof RA, Sunahara RK, Traynor JR, Neubig RR. Identification of small-molecule inhibitors of RGS4 using a high-throughput flow cytometry protein interaction assay. Mol Pharmacol 2006; 71:169-75. [PMID: 17012620 DOI: 10.1124/mol.106.028670] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Regulators of G-protein signaling (RGS) proteins are important components of signal transduction pathways initiated through G-protein-coupled receptors (GPCRs). RGS proteins accelerate the intrinsic GTPase activity of G-protein alpha-subunits (Galpha) and thus shorten the time course and reduce the magnitude of G-protein alpha- and betagamma-subunit signaling. Inhibiting RGS action has been proposed as a means to enhance the activity and specificity of GPCR agonist drugs, but pharmacological targeting of protein-protein interactions has typically been difficult. The aim of this project was to identify inhibitors of RGS4. Using a Luminex 96-well plate bead analyzer and a novel flow-cytometric protein interaction assay to assess Galpha-RGS interactions in a high-throughput screen, we identified the first small-molecule inhibitor of an RGS protein. Of 3028 compounds screened, 1, methyl N-[(4-chlorophenyl)sulfonyl]-4-nitrobenzenesulfinimidoate (CCG-4986), inhibited RGS4/Galpha(o) binding with 3 to 5 muM potency. It binds to RGS4, inhibits RGS4 stimulation of Galpha(o) GTPase activity in vitro, and prevents RGS4 regulation of mu-opioid-inhibited adenylyl cyclase activity in permeabilized cells. Furthermore, CCG-4986 is selective for RGS4 and does not inhibit RGS8. Thus, we demonstrate the feasibility of targeting RGS/Galpha protein-protein interactions with small molecules as a novel means to modulate GPCR-mediated signaling processes.
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Affiliation(s)
- David L Roman
- Department of Pharmacology, University of Michigan Medical School, 1150 W. Medical Center Drive, 1303 MSRB III, Ann Arbor, MI 41809, USA
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26
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Seeman P, Schwarz J, Chen JF, Szechtman H, Perreault M, McKnight GS, Roder JC, Quirion R, Boksa P, Srivastava LK, Yanai K, Weinshenker D, Sumiyoshi T. Psychosis pathways converge via D2high dopamine receptors. Synapse 2006; 60:319-46. [PMID: 16786561 DOI: 10.1002/syn.20303] [Citation(s) in RCA: 233] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The objective of this review is to identify a target or biomarker of altered neurochemical sensitivity that is common to the many animal models of human psychoses associated with street drugs, brain injury, steroid use, birth injury, and gene alterations. Psychosis in humans can be caused by amphetamine, phencyclidine, steroids, ethanol, and brain lesions such as hippocampal, cortical, and entorhinal lesions. Strikingly, all of these drugs and lesions in rats lead to dopamine supersensitivity and increase the high-affinity states of dopamine D2 receptors, or D2High, by 200-400% in striata. Similar supersensitivity and D2High elevations occur in rats born by Caesarian section and in rats treated with corticosterone or antipsychotics such as reserpine, risperidone, haloperidol, olanzapine, quetiapine, and clozapine, with the latter two inducing elevated D2High states less than that caused by haloperidol or olanzapine. Mice born with gene knockouts of some possible schizophrenia susceptibility genes are dopamine supersensitive, and their striata reveal markedly elevated D2High states; suchgenes include dopamine-beta-hydroxylase, dopamine D4 receptors, G protein receptor kinase 6, tyrosine hydroxylase, catechol-O-methyltransferase, the trace amine-1 receptor, regulator of G protein signaling RGS9, and the RIIbeta form of cAMP-dependent protein kinase (PKA). Striata from mice that are not dopamine supersensitive did not reveal elevated D2High states; these include mice with knockouts of adenosine A2A receptors, glycogen synthase kinase GSK3beta, metabotropic glutamate receptor 5, dopamine D1 or D3 receptors, histamine H1, H2, or H3 receptors, and rats treated with ketanserin or aD1 antagonist. The evidence suggests that there are multiple pathways that convergetoelevate the D2High state in brain regions and that this elevation may elicit psychosis. This proposition is supported by the dopamine supersensitivity that is a common feature of schizophrenia and that also occurs in many types of genetically altered, drug-altered, and lesion-altered animals. Dopamine supersensitivity, in turn, correlates with D2High states. The finding that all antipsychotics, traditional and recent ones, act on D2High dopamine receptors further supports the proposition.
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Affiliation(s)
- Philip Seeman
- Department of Pharmacology, University of Toronto, and Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada M5S 1A8.
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27
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Neitzel KL, Hepler JR. Cellular mechanisms that determine selective RGS protein regulation of G protein-coupled receptor signaling. Semin Cell Dev Biol 2006; 17:383-9. [PMID: 16647283 DOI: 10.1016/j.semcdb.2006.03.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Regulators of G protein signaling (RGS proteins) bind directly to activated Galpha subunits to inhibit their signaling. However, recent findings show that RGS proteins selectively regulate signaling by certain G protein-coupled receptors (GPCRs) in cells, irrespective of the coupled G protein. New studies support an emerging model that suggests RGS proteins utilize both direct and indirect mechanisms to form stable functional pairs with preferred GPCRs to selectively modulate the signaling functions of those receptors and linked G proteins. Here, we discuss these findings and their implications for established models of GPCR signaling.
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Affiliation(s)
- Karen L Neitzel
- Department of Pharmacology, Emory University School of Medicine, G205 Rollins Research Center, 1510 Clifton Road, Atlanta, GA 30322, USA
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28
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Kampman O, Illi A, Hänninen K, Katila H, Anttila S, Rontu R, Mattila KM, Leinonen E, Lehtimäki T. RGS4 genotype is not associated with antipsychotic medication response in schizophrenia. J Neural Transm (Vienna) 2006; 113:1563-8. [PMID: 16604300 DOI: 10.1007/s00702-006-0445-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 01/09/2006] [Indexed: 11/25/2022]
Abstract
The aims of the present study were to compare the allele frequencies of a common single nucleotide polymorphism located upstream of the regulator of G-protein signaling 4 (RGS4) gene (T > G, Rs 951436) in 219 Finnish patients with schizophrenia and in 389 control subjects, to analyze corresponding frequencies between two different subtypes of 93 schizophrenia patients according to their medication response, and to study the effect of this SNP on age at onset in schizophrenia. The RGS4 (T > G, Rs 951436) genotype was not associated with incidence or age at onset in schizophrenia. Neither was the RGS4 genotype associated with medication response with two different subpopulations with schizophrenia.
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Affiliation(s)
- O Kampman
- Medical School, University of Tampere, Tampere, Finland.
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29
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Weng J, Ma W, Mitchell D, Zhang J, Liu M. Regulation of human prostate-specific G-protein coupled receptor, PSGR, by two distinct promoters and growth factors. J Cell Biochem 2006; 96:1034-48. [PMID: 16149059 DOI: 10.1002/jcb.20600] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
PSGR is a newly identified human prostate tissue-specific gene belonging to the G-protein coupled receptor (GPCR) family. Overexpression of PSGR is associated with human prostate intraepithelial neoplasia (PIN) and prostate tumors, suggesting PSGR may play an important role in early prostate cancer development and progression. To understand the regulation of tissue-specific expression of human PSGR and its upregulation mechanism in prostate cancers, we characterized the promoter region of PSGR and analyzed the control mechanism for PSGR expression in human prostate tissues/cells. In this report, we demonstrate that two distinct promoters control the transcriptional regulation of PSGR in human prostate cells. The first promoter region includes exon 1 and a TATA box at -31 site. The minimal DNA sequence with promoter activity is about 123 bp upstream of exon 1. Exon 1 contains tissue specific regulatory activity for the first promoter of PSGR gene. The second promoter is located in the upstream region of exon 2, which is a TATA-less and non-GC-rich promoter. Primer extension and RNA protection assays (RPA) revealed that the transcription driven by the second promoter is initiated at the junction of intron and exon 2 within a cluster of nucleotides located about 250 bp upstream from the junction. Both promoters show prostate cell-specific characteristics in our luciferase assays in transfected cells. Furthermore, we investigated the regulation of the promoter activities of the PSGR gene by different growth factors and cytokines, and demonstrated that interleukin-6 (IL-6) activates the promoter activities of PSGR in human prostate cancer cells. These data suggest that two functional promoters regulate the transcriptional expression of PSGR in human prostate tissues and PSGR is a new target for IL-6 transcriptional regulation.
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Affiliation(s)
- Jinsheng Weng
- Alkek Institute of Biosciences and Technology, Department of Medical Biochemistry and Genetics, Texas A&M University System Health Science Center, 2121 W. Holcombe Blvd., Houston, Texas 77030, USA
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30
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Riddle EL, Rana BK, Murthy KK, Rao F, Eskin E, O'Connor DT, Insel PA. Polymorphisms and Haplotypes of the Regulator of G Protein Signaling-2 Gene in Normotensives and Hypertensives. Hypertension 2006; 47:415-20. [PMID: 16432041 DOI: 10.1161/01.hyp.0000200714.81990.61] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Regulator of G protein signaling (RGS) proteins stimulate the GTPase activity of Galpha subunits of heterotrimeric G proteins, thereby negatively regulating G protein-coupled receptor signaling. RGS2, which preferentially alters Galphaq-mediated signaling, may be important for cardiovascular health, because knockout of RGS2 in mice is associated with altered smooth muscle relaxation and hypertension. In this study, we determined genetic variation in the human RGS2 gene by sequencing DNA in normotensive and hypertensive populations of whites (n=128) and blacks (n=122). We identified 14 single nucleotide polymorphisms and 2 two-base insertion/deletions (in/del; 1891 to 1892 TC and 2138 to 2139 AA). Although most of the genetic variants were found at low allelic frequency, in particular in coding regions, the 1891 to 1892 TC and 2138 to 2139 AA intronic in/del were in linkage disequilibrium and were associated with hypertension in blacks (P<0.05). We defined several haplotypes for the RGS2 gene, certain of which showed striking differences between whites and blacks. Additionally, 2 haplotypes had significantly different frequencies between hypertensive and normotensive black groups (P<0.05). We conclude that RGS2 is genetically conserved within coding regions but that the intronic in/del define ethnicity-specific haplotypes. Moreover, certain RGS2 variants that occur at greater frequency in hypertensive blacks may serve as ethnicity-specific genetic variants for this disease.
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Affiliation(s)
- Evan L Riddle
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093, USA
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31
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Benians A, Nobles M, Hosny S, Tinker A. Regulators of G-protein signaling form a quaternary complex with the agonist, receptor, and G-protein. A novel explanation for the acceleration of signaling activation kinetics. J Biol Chem 2005; 280:13383-94. [PMID: 15677457 DOI: 10.1074/jbc.m410163200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Regulators of G-protein signaling (RGS) proteins modulate signaling through heterotrimeric G-proteins. They act to enhance the intrinsic GTPase activity of the Galpha subunit but paradoxically have also been shown to enhance receptor-stimulated activation. To study this paradox, we used a G-protein gated K+ channel to report the dynamics of the G-protein cycle and fluorescence resonance energy transfer techniques with cyan and yellow fluorescent protein-tagged proteins to report physical interaction. Our data show that the acceleration of the activation kinetics is dissociated from deactivation kinetics and dependent on receptor and RGS type, G-protein isoform, and RGS expression levels. By using fluorescently tagged proteins, fluorescence resonance energy transfer microscopy showed a stable physical interaction between the G-protein alpha subunit and RGS (RGS8 and RGS7) that is independent of the functional state of the G-protein. RGS8 does not directly interact with G-protein-coupled receptors. Our data show participation of the RGS in the ternary complex between agonist-receptor and G-protein to form a "quaternary complex." Thus we propose a novel model for the action of RGS proteins in the G-protein cycle in which the RGS protein appears to enhance the "kinetic efficacy" of the ternary complex, by direct association with the G-protein alpha subunit.
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Affiliation(s)
- Amy Benians
- BHF Laboratories and Department of Medicine, University College London, Room 420, 4th Floor, 5 University Street, London WC1E 6JJ, United Kingdom
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32
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Young KH, Wang Y, Bender C, Ajit S, Ramirez F, Gilbert A, Nieuwenhuijsen BW. Yeast-Based Screening for Inhibitors of RGS Proteins. Methods Enzymol 2004; 389:277-301. [PMID: 15313572 DOI: 10.1016/s0076-6879(04)89017-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This article provides information on two screening platforms for the identification of regulators of G-protein signaling (RGS) protein modulators. Utilization of the yeast pheromone response pathway enabled the creation of a functional screen for RGS4 modulators. The RGSZ1-focused screen employs advances in yeast two-hybrid screening technologies and targets the protein-protein interface of the RGS domain/Galpha interaction. Moreover, the RGSZ1 screen provides the opportunity to multiplex the screening of two targets of interest, given the development of two different luciferase reporter genes that enabled sequential determination and intraassay controls. The screen formats were validated, implemented, and conducted as automated 384-well, liquid-based, high-throughput small molecule screens. Primary "hits" were confirmed using benchtop 96-well formats of these assays and advanced to in vitro functional evaluation assays. The yeast-based assay platforms provide robust cellular assays that result in the identification of small molecule modulators for both RGS targets. These molecules can serve both as tools with which to probe biological implications of RGS proteins and as potential starting points toward the development of novel modulators of G-protein signaling pathways. Such modulators may show potential for controlling and treating diseases resulting from inappropriate activity of G-protein signaling pathways.
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Affiliation(s)
- Kathleen H Young
- Neuroscience Discovery Research, Wyeth Research, Princeton, New Jersey 08543-8000, USA
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33
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Simonds WF. G Protein-Regulated Signaling Dysfunction in Human Disease. J Investig Med 2003. [DOI: 10.1177/108155890305100421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- William F. Simonds
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Bethesda, Maryland
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