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Ahlers-Dannen KE, Spicer MM, Fisher RA. RGS Proteins as Critical Regulators of Motor Function and Their Implications in Parkinson's Disease. Mol Pharmacol 2020; 98:730-738. [PMID: 32015009 DOI: 10.1124/mol.119.118836] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 01/25/2020] [Indexed: 11/22/2022] Open
Abstract
Parkinson disease (PD) is a devastating, largely nonfamilial, age-related disorder caused by the progressive loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc). Release of DA from these neurons into the dorsal striatum is crucial for regulating movement and their loss causes PD. Unfortunately, the mechanisms underlying SNc neurodegeneration remain unclear, and currently there is no cure for PD, only symptomatic treatments. Recently, several regulator of G protein signaling (RGS) proteins have emerged as critical modulators of PD pathogenesis and/or motor dysfunction and dyskinesia: RGSs 4, 6, 9, and 10. Striatal RGS4 has been shown to exacerbate motor symptoms of DA loss by suppressing M4-autoreceptor-Gα i/o signaling in striatal cholinergic interneurons. RGS6 and RGS9 are key regulators of D2R-Gα i/o signaling in SNc DA neurons and striatal medium spiny neurons, respectively. RGS6, expressed in human and mouse SNc DA neurons, suppresses characteristic PD hallmarks in aged mice, including SNc DA neuron loss, motor deficits, and α-synuclein accumulation. After DA depletion, RGS9 (through its inhibition of medium spiny neuron D2R signaling) suppresses motor dysfunction induced by L-DOPA or D2R-selective agonists. RGS10 is highly expressed in microglia, the brain's resident immune cells. Within the SNc, RGS10 may promote DA neuron survival through the upregulation of prosurvival genes and inhibition of microglial inflammatory factor expression. Thus, RGSs 4, 6, 9, and 10 are critical modulators of cell signaling pathways that promote SNc DA neuron survival and/or proper motor control. Accordingly, these RGS proteins represent novel therapeutic targets for the treatment of PD pathology. SIGNIFICANCE STATEMENT: Parkinson disease (PD), the most common movement disorder, is a progressive neurodegenerative disease characterized by substantia nigra pars compacta (SNc) dopamine (DA) neuron loss and subsequent motor deficits. Current PD therapies only target disease motor symptomology and are fraught with side effects. Therefore, researchers have begun to explore alternative therapeutic options. Regulator of G protein signaling (RGS) proteins, whether primarily expressed in SNc DA neurons (RGS6), striatal neurons (RGSs 4 and 9), or microglia (RGS10), modulate key signaling pathways important for SNc DA neuron survival and/or proper motor control. As such, RGS proteins represent novel therapeutic targets in PD.
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Affiliation(s)
- Katelin E Ahlers-Dannen
- Department of Neuroscience and Pharmacology (K.E.A.-D., M.M.S., R.A.F.), Iowa Neuroscience Institute (R.A.F.), and Interdisciplinary Graduate Program in Molecular Medicine (M.M.S., R.A.F.), University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Mackenzie M Spicer
- Department of Neuroscience and Pharmacology (K.E.A.-D., M.M.S., R.A.F.), Iowa Neuroscience Institute (R.A.F.), and Interdisciplinary Graduate Program in Molecular Medicine (M.M.S., R.A.F.), University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Rory A Fisher
- Department of Neuroscience and Pharmacology (K.E.A.-D., M.M.S., R.A.F.), Iowa Neuroscience Institute (R.A.F.), and Interdisciplinary Graduate Program in Molecular Medicine (M.M.S., R.A.F.), University of Iowa Carver College of Medicine, Iowa City, Iowa
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2
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Patil DN, Rangarajan ES, Novick SJ, Pascal BD, Kojetin DJ, Griffin PR, Izard T, Martemyanov KA. Structural organization of a major neuronal G protein regulator, the RGS7-Gβ5-R7BP complex. eLife 2018; 7:42150. [PMID: 30540250 PMCID: PMC6310461 DOI: 10.7554/elife.42150] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/12/2018] [Indexed: 01/03/2023] Open
Abstract
Signaling by the G-protein-coupled receptors (GPCRs) plays fundamental role in a vast number of essential physiological functions. Precise control of GPCR signaling requires action of regulators of G protein signaling (RGS) proteins that deactivate heterotrimeric G proteins. RGS proteins are elaborately regulated and comprise multiple domains and subunits, yet structural organization of these assemblies is poorly understood. Here, we report a crystal structure and dynamics analyses of the multisubunit complex of RGS7, a major regulator of neuronal signaling with key roles in controlling a number of drug target GPCRs and links to neuropsychiatric disease, metabolism, and cancer. The crystal structure in combination with molecular dynamics and mass spectrometry analyses reveals unique organizational features of the complex and long-range conformational changes imposed by its constituent subunits during allosteric modulation. Notably, several intermolecular interfaces in the complex work in synergy to provide coordinated modulation of this key GPCR regulator.
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Affiliation(s)
- Dipak N Patil
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
| | - Erumbi S Rangarajan
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States
| | - Scott J Novick
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, United States
| | - Bruce D Pascal
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, United States
| | - Douglas J Kojetin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States
| | - Patrick R Griffin
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States.,Department of Molecular Medicine, The Scripps Research Institute, Jupiter, United States
| | - Tina Izard
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, United States
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3
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Huang H, Zhu CT, Skuja LL, Hayden DJ, Hart AC. Genome-Wide Screen for Genes Involved in Caenorhabditis elegans Developmentally Timed Sleep. G3 (BETHESDA, MD.) 2017; 7:2907-2917. [PMID: 28743807 PMCID: PMC5592919 DOI: 10.1534/g3.117.300071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/21/2017] [Indexed: 12/24/2022]
Abstract
In Caenorhabditis elegans, Notch signaling regulates developmentally timed sleep during the transition from L4 larval stage to adulthood (L4/A) . To identify core sleep pathways and to find genes acting downstream of Notch signaling, we undertook the first genome-wide, classical genetic screen focused on C. elegans developmentally timed sleep. To increase screen efficiency, we first looked for mutations that suppressed inappropriate anachronistic sleep in adult hsp::osm-11 animals overexpressing the Notch coligand OSM-11 after heat shock. We retained suppressor lines that also had defects in L4/A developmentally timed sleep, without heat shock overexpression of the Notch coligand. Sixteen suppressor lines with defects in developmentally timed sleep were identified. One line carried a new allele of goa-1; loss of GOA-1 Gαo decreased C. elegans sleep. Another line carried a new allele of gpb-2, encoding a Gβ5 protein; Gβ5 proteins have not been previously implicated in sleep. In other scenarios, Gβ5 GPB-2 acts with regulators of G protein signaling (RGS proteins) EAT-16 and EGL-10 to terminate either EGL-30 Gαq signaling or GOA-1 Gαo signaling, respectively. We found that loss of Gβ5 GPB-2 or RGS EAT-16 decreased L4/A sleep. By contrast, EGL-10 loss had no impact. Instead, loss of RGS-1 and RGS-2 increased sleep. Combined, our results suggest that, in the context of L4/A sleep, GPB-2 predominantly acts with EAT-16 RGS to inhibit EGL-30 Gαq signaling. These results confirm the importance of G protein signaling in sleep and demonstrate that these core sleep pathways function genetically downstream of the Notch signaling events promoting sleep.
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Affiliation(s)
- Huiyan Huang
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - Chen-Tseh Zhu
- Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912
| | - Lukas L Skuja
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - Dustin J Hayden
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - Anne C Hart
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
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4
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Collins KM, Bode A, Fernandez RW, Tanis JE, Brewer JC, Creamer MS, Koelle MR. Activity of the C. elegans egg-laying behavior circuit is controlled by competing activation and feedback inhibition. eLife 2016; 5. [PMID: 27849154 PMCID: PMC5142809 DOI: 10.7554/elife.21126] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/14/2016] [Indexed: 01/13/2023] Open
Abstract
Like many behaviors, Caenorhabditis elegans egg laying alternates between inactive and active states. To understand how the underlying neural circuit turns the behavior on and off, we optically recorded circuit activity in behaving animals while manipulating circuit function using mutations, optogenetics, and drugs. In the active state, the circuit shows rhythmic activity phased with the body bends of locomotion. The serotonergic HSN command neurons initiate the active state, but accumulation of unlaid eggs also promotes the active state independent of the HSNs. The cholinergic VC motor neurons slow locomotion during egg-laying muscle contraction and egg release. The uv1 neuroendocrine cells mechanically sense passage of eggs through the vulva and release tyramine to inhibit egg laying, in part via the LGC-55 tyramine-gated Cl- channel on the HSNs. Our results identify discrete signals that entrain or detach the circuit from the locomotion central pattern generator to produce active and inactive states. DOI:http://dx.doi.org/10.7554/eLife.21126.001 It has been said that if the human brain were so simple that we could understand it, we would be so simple that we couldn’t. This quote neatly captures the challenge of working out how 80 billion neurons collectively generate our thoughts and behavior. Fortunately, the nervous system is also organized into simpler units called circuits. Each consists of a relatively small number of neurons, which communicate with one another to control as little as a single behavior. These circuits should in principle be simple enough for us to understand, particularly if we study them in nervous systems less complex than our own. Despite this, there is currently not a single circuit in any organism in which we can explain how communication between individual neurons generates behavior. Collins et al. therefore set out to characterize a simple neural circuit in one of the simplest model organisms: the egg-laying circuit of the worm C. elegans. Using mutations, drugs and molecular genetic techniques, Collins et al. systematically altered the activity and signaling of each of the neurons within the egg-laying circuit. The experiments revealed that cells called command neurons trigger egg laying by producing signals that switch on the rest of the circuit. Once activated, the circuit is able to respond to waves of activity from a second circuit – called the central pattern generator – that also controls the worm’s movement. Finally, laying an egg activates a third set of neurons, which release a signal that returns the circuit to its inactive state. The use of distinct signals and neurons to activate the circuit, to coordinate its ongoing activity, and to inactivate the circuit when its task is complete also applies to many other neural circuits. Now that these signals have been identified in one circuit, it should be possible to build on these findings to better understand how others work. DOI:http://dx.doi.org/10.7554/eLife.21126.002
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Affiliation(s)
- Kevin M Collins
- Department of Biology, University of Miami, Coral Gables, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Addys Bode
- Department of Biology, University of Miami, Coral Gables, United States
| | - Robert W Fernandez
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Jessica E Tanis
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Jacob C Brewer
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Matthew S Creamer
- Interdepartmental Neuroscience Program, Yale University, New Haven, United States
| | - Michael R Koelle
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Interdepartmental Neuroscience Program, Yale University, New Haven, United States
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Shamseldin HE, Masuho I, Alenizi A, Alyamani S, Patil DN, Ibrahim N, Martemyanov KA, Alkuraya FS. GNB5 mutation causes a novel neuropsychiatric disorder featuring attention deficit hyperactivity disorder, severely impaired language development and normal cognition. Genome Biol 2016; 17:195. [PMID: 27677260 PMCID: PMC5037613 DOI: 10.1186/s13059-016-1061-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 09/12/2016] [Indexed: 11/23/2022] Open
Abstract
Background Neuropsychiatric disorders are common forms of disability in humans. Despite recent progress in deciphering the genetics of these disorders, their phenotypic complexity continues to be a major challenge. Mendelian neuropsychiatric disorders are rare but their study has the potential to unravel novel mechanisms that are relevant to their complex counterparts. Results In an extended consanguineous family, we identified a novel neuropsychiatric phenotype characterized by severe speech impairment, variable expressivity of attention deficit hyperactivity disorder (ADHD), and motor delay. We identified the disease locus through linkage analysis on 15q21.2, and exome sequencing revealed a novel missense variant in GNB5. GNB5 encodes an atypical β subunit of the heterotrimeric GTP-binding proteins (Gβ5). Gβ5 is enriched in the central nervous system where it forms constitutive complexes with members of the regulator of G protein signaling family of proteins to modulate neurotransmitter signaling that affects a number of neurobehavioral outcomes. Here, we show that the S81L mutant form of Gβ5 has significantly impaired activity in terminating responses that are elicited by dopamine. Conclusions We demonstrate that these deficits originate from the impaired expression of the mutant Gβ5 protein, resulting in the decreased ability to stabilize regulator of G protein signaling complexes. Our data suggest that this novel neuropsychiatric phenotype is the human equivalent of Gnb5 deficiency in mice, which manifest motor deficits and hyperactivity, and highlight a critical role of Gβ5 in normal behavior as well as language and motor development in humans. Electronic supplementary material The online version of this article (doi:10.1186/s13059-016-1061-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hanan E Shamseldin
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA
| | - Ahmed Alenizi
- Department of Pediatrics, King Saud Medical City, Riyadh, Saudi Arabia
| | - Suad Alyamani
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Dipak N Patil
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA.
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia. .,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
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6
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Ahlers KE, Chakravarti B, Fisher RA. RGS6 as a Novel Therapeutic Target in CNS Diseases and Cancer. AAPS JOURNAL 2016; 18:560-72. [PMID: 27002730 DOI: 10.1208/s12248-016-9899-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 02/25/2016] [Indexed: 12/17/2022]
Abstract
Regulator of G protein signaling (RGS) proteins are gatekeepers regulating the cellular responses induced by G protein-coupled receptor (GPCR)-mediated activation of heterotrimeric G proteins. Specifically, RGS proteins determine the magnitude and duration of GPCR signaling by acting as a GTPase-activating protein for Gα subunits, an activity facilitated by their semiconserved RGS domain. The R7 subfamily of RGS proteins is distinguished by two unique domains, DEP/DHEX and GGL, which mediate membrane targeting and stability of these proteins. RGS6, a member of the R7 subfamily, has been shown to specifically modulate Gαi/o protein activity which is critically important in the central nervous system (CNS) for neuronal responses to a wide array of neurotransmitters. As such, RGS6 has been implicated in several CNS pathologies associated with altered neurotransmission, including the following: alcoholism, anxiety/depression, and Parkinson's disease. In addition, unlike other members of the R7 subfamily, RGS6 has been shown to regulate G protein-independent signaling mechanisms which appear to promote both apoptotic and growth-suppressive pathways that are important in its tumor suppressor function in breast and possibly other tissues. Further highlighting the importance of RGS6 as a target in cancer, RGS6 mediates the chemotherapeutic actions of doxorubicin and blocks reticular activating system (Ras)-induced cellular transformation by promoting degradation of DNA (cytosine-5)-methyltransferase 1 (DNMT1) to prevent its silencing of pro-apoptotic and tumor suppressor genes. Together, these findings demonstrate the critical role of RGS6 in regulating both G protein-dependent CNS pathology and G protein-independent cancer pathology implicating RGS6 as a novel therapeutic target.
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Affiliation(s)
- Katelin E Ahlers
- Department of Pharmacology, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 2-505 Bowen Science Building, Iowa City, Iowa, 52242, USA
| | - Bandana Chakravarti
- Department of Pharmacology, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 2-505 Bowen Science Building, Iowa City, Iowa, 52242, USA
| | - Rory A Fisher
- Department of Pharmacology, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 2-505 Bowen Science Building, Iowa City, Iowa, 52242, USA. .,Department of Internal Medicine, The Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, 52242, USA.
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Stewart A, Maity B, Fisher RA. Two for the Price of One: G Protein-Dependent and -Independent Functions of RGS6 In Vivo. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 133:123-51. [PMID: 26123305 DOI: 10.1016/bs.pmbts.2015.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Regulator of G protein signaling 6 (RGS6) is unique among the members of the RGS protein family as it remains the only protein with the demonstrated capacity to control G protein-dependent and -independent signaling cascades in vivo. RGS6 inhibits signaling mediated by γ-aminobutyric acid B receptors, serotonin 1A receptors, μ opioid receptors, and muscarinic acetylcholine 2 receptors. RGS6 deletion triggers distinct behavioral phenotypes resulting from potentiated signaling by these G protein-coupled receptors namely ataxia, a reduction in anxiety and depression, enhanced analgesia, and increased parasympathetic tone, respectively. In addition, RGS6 possesses potent proapoptotic and growth suppressive actions. In heart, RGS6-dependent reactive oxygen species (ROS) production promotes doxorubicin (Dox)-induced cardiomyopathy, while in cancer cells RGS6/ROS signaling is necessary for activation of the ataxia telangiectasia mutated/p53/apoptosis pathway required for the chemotherapeutic efficacy of Dox. Further, by facilitating Tip60 (trans-acting regulator protein of HIV type 1-interacting protein 60 kDa)-dependent DNA methyltransferase 1 degradation, RGS6 suppresses cellular transformation in response to oncogenic Ras. The culmination of these G protein-independent actions results in potent tumor suppressor actions of RGS6 in the murine mammary epithelium. This work summarizes evidence from human genetic studies and model animals implicating RGS6 in normal physiology, disease, and the pharmacological actions of multiple drugs. Though efforts by multiple laboratories have contributed to the ever-growing RGS6 oeuvre, the pleiotropic nature of this gene will likely lead to additional work detailing the importance of RGS6 in neuropsychiatric disorders, cardiovascular disease, and cancer.
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Affiliation(s)
- Adele Stewart
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Biswanath Maity
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Rory A Fisher
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
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Orlandi C, Xie K, Masuho I, Fajardo-Serrano A, Lujan R, Martemyanov KA. Orphan Receptor GPR158 Is an Allosteric Modulator of RGS7 Catalytic Activity with an Essential Role in Dictating Its Expression and Localization in the Brain. J Biol Chem 2015; 290:13622-39. [PMID: 25792749 DOI: 10.1074/jbc.m115.645374] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Indexed: 11/06/2022] Open
Abstract
Regulators of G protein signaling control the duration and extent of signaling via G protein-coupled receptor (GPCR) pathways by accelerating the GTP hydrolysis on G protein α subunits thereby promoting termination of GPCR signaling. A member of this family, RGS7, plays a critical role in the nervous system where it regulates multiple neurotransmitter GPCRs that mediate vision, memory, and the action of addictive drugs. Previous studies have established that in vivo RGS7 forms mutually exclusive complexes with the membrane protein RGS7-binding protein or the orphan receptor GPR158. In this study, we examine the impact of GPR158 on RGS7 in the brain. We report that knock-out of GPR158 in mice results in marked post-transcriptional destabilization of RGS7 and substantial loss of its association with membranes in several brain regions. We further identified the RGS7-binding site in the C terminus of GPR158 and found that it shares significant homology with the RGS7-binding protein. The proximal portion of the GPR158 C terminus additionally contained a conserved sequence that was capable of enhancing RGS7 GTPase-activating protein activity in solution by an allosteric mechanism acting in conjunction with the regulators of the G protein signaling-binding domain. The distal portion of the GPR158 C terminus contained several phosphodiesterase E γ-like motifs and selectively recruited G proteins in their activated state. The results of this study establish GPR158 as an essential regulator of RGS7 in the native nervous system with a critical role in controlling its expression, membrane localization, and catalytic activity.
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Affiliation(s)
- Cesare Orlandi
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458 and
| | - Keqiang Xie
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458 and
| | - Ikuo Masuho
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458 and
| | - Ana Fajardo-Serrano
- the Instituto de Investigación en Descapacidades Neuronales (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Rafael Lujan
- the Instituto de Investigación en Descapacidades Neuronales (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Kirill A Martemyanov
- From the Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458 and
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Orlandi C, Cao Y, Martemyanov KA. Orphan receptor GPR179 forms macromolecular complexes with components of metabotropic signaling cascade in retina ON-bipolar neurons. Invest Ophthalmol Vis Sci 2013; 54:7153-61. [PMID: 24114537 DOI: 10.1167/iovs.13-12907] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE In the mammalian retina, synaptic transmission between light-excited rod photoreceptors and downstream ON-bipolar neurons is indispensable for dim vision, and disruption of this process leads to congenital stationary night blindness in human patients. The ON-bipolar neurons use the metabotropic signaling cascade, initiated by the mGluR6 receptor, to generate depolarizing responses to light-induced changes in neurotransmitter glutamate release from the photoreceptor axonal terminals. Evidence for the identity of the components involved in transducing these signals is growing rapidly. Recently, the orphan receptor, GPR179, a member of the G protein-coupled receptor (GPCR) superfamily, has been shown to be indispensable for the synaptic responses of ON-bipolar cells. In our study, we investigated the interaction of GPR179 with principle components of the signal transduction cascade. METHODS We used immunoprecipitation and proximity ligation assays in transfected cells and native retinas to characterize the protein-protein interactions involving GPR179. The influence of cascade components on GPR179 localization was examined through immunohistochemical staining of the retinas from genetic mouse models. RESULTS We demonstrated that, in mouse retinas, GPR179 forms physical complexes with the main components of the metabotropic cascade, recruiting mGluR6, TRPM1, and the RGS proteins. Elimination of mGluR6 or RGS proteins, but not TRPM1, detrimentally affects postsynaptic targeting or GPR179 expression. CONCLUSIONS These observations suggest that the mGluR6 signaling cascade is scaffolded as a macromolecular complex in which the interactions between the components ensure the optimal spatiotemporal characteristics of signal transduction.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida
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10
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McVeigh P, Atkinson L, Marks NJ, Mousley A, Dalzell JJ, Sluder A, Hammerland L, Maule AG. Parasite neuropeptide biology: Seeding rational drug target selection? Int J Parasitol Drugs Drug Resist 2012; 2:76-91. [PMID: 24533265 PMCID: PMC3862435 DOI: 10.1016/j.ijpddr.2011.10.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/25/2011] [Accepted: 10/28/2011] [Indexed: 01/16/2023]
Abstract
The rationale for identifying drug targets within helminth neuromuscular signalling systems is based on the premise that adequate nerve and muscle function is essential for many of the key behavioural determinants of helminth parasitism, including sensory perception/host location, invasion, locomotion/orientation, attachment, feeding and reproduction. This premise is validated by the tendency of current anthelmintics to act on classical neurotransmitter-gated ion channels present on helminth nerve and/or muscle, yielding therapeutic endpoints associated with paralysis and/or death. Supplementary to classical neurotransmitters, helminth nervous systems are peptide-rich and encompass associated biosynthetic and signal transduction components - putative drug targets that remain to be exploited by anthelmintic chemotherapy. At this time, no neuropeptide system-targeting lead compounds have been reported, and given that our basic knowledge of neuropeptide biology in parasitic helminths remains inadequate, the short-term prospects for such drugs remain poor. Here, we review current knowledge of neuropeptide signalling in Nematoda and Platyhelminthes, and highlight a suite of 19 protein families that yield deleterious phenotypes in helminth reverse genetics screens. We suggest that orthologues of some of these peptidergic signalling components represent appealing therapeutic targets in parasitic helminths.
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Affiliation(s)
- Paul McVeigh
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Louise Atkinson
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Nikki J. Marks
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Angela Mousley
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Johnathan J. Dalzell
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Ann Sluder
- Scynexis Inc., P.O. Box 12878, Research Triangle Park, NC 27709-2878, USA
| | | | - Aaron G. Maule
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
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11
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Orlandi C, Posokhova E, Masuho I, Ray TA, Hasan N, Gregg RG, Martemyanov KA. GPR158/179 regulate G protein signaling by controlling localization and activity of the RGS7 complexes. ACTA ACUST UNITED AC 2012; 197:711-9. [PMID: 22689652 PMCID: PMC3373406 DOI: 10.1083/jcb.201202123] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Interaction of RGS proteins with orphan GPCRs promotes signaling compartmentalization and specificity. The extent and temporal characteristics of G protein–coupled receptor (GPCR) signaling are shaped by the regulator of G protein signaling (RGS) proteins, which promote G protein deactivation. With hundreds of GPCRs and dozens of RGS proteins, compartmentalization plays a key role in establishing signaling specificity. However, the molecular details and mechanisms of this process are poorly understood. In this paper, we report that the R7 group of RGS regulators is controlled by interaction with two previously uncharacterized orphan GPCRs: GPR158 and GPR179. We show that GPR158/179 recruited RGS complexes to the plasma membrane and augmented their ability to regulate GPCR signaling. The loss of GPR179 in a mouse model of night blindness prevented targeting of RGS to the postsynaptic compartment of bipolar neurons in the retina, illuminating the role of GPR179 in night vision. We propose that the interaction of RGS proteins with orphan GPCRs promotes signaling selectivity in G protein pathways.
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Affiliation(s)
- Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
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Xie K, Ge S, Collins VE, Haynes CL, Renner KJ, Meisel RL, Lujan R, Martemyanov KA. Gβ5-RGS complexes are gatekeepers of hyperactivity involved in control of multiple neurotransmitter systems. Psychopharmacology (Berl) 2012; 219:823-34. [PMID: 21766168 PMCID: PMC3260372 DOI: 10.1007/s00213-011-2409-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Accepted: 07/01/2011] [Indexed: 12/25/2022]
Abstract
RATIONALE AND OBJECTIVES Our knowledge about genes involved in the control of basal motor activity that may contribute to the pathology of the hyperactivity disorders, e.g., attention deficit hyperactivity disorder (ADHD), is limited. Disruption of monoamine neurotransmitter signaling through G protein-coupled receptors (GPCR) is considered to be a major contributing factor to the etiology of the ADHD. Genetic association evidence and functional data suggest that regulators of G protein signaling proteins of the R7 family (R7 RGS) that form obligatory complexes with type 5 G protein beta subunit (Gβ5) and negatively regulate signaling downstream from monoamine GPCRs may play a role in controlling hyperactivity. METHODS To test this hypothesis, we conducted behavioral, pharmacological, and neurochemical studies using a genetic mouse model that lacked Gβ5, a subunit essential for the expression of the entire R7 RGS family. RESULTS Elimination of Gβ5-RGS complexes led to a striking level of hyperactivity that far exceeds activity levels previously observed in animal models. This hyperactivity was accompanied by motor learning deficits and paradoxical behavioral sensitization to a novel environment. Neurochemical studies indicated that Gβ5-RGS-deficient mice had higher sensitivity of inhibitory GPCR signaling and deficits in basal levels, release, and reuptake of dopamine. Surprisingly, pharmacological treatment with monoamine reuptake inhibitors failed to alter hyperactivity. In contrast, blockade of NMDA receptors reversed the expression of hyperactivity in Gβ5-RGS-deficient mice. CONCLUSIONS These findings establish that Gβ5-RGS complexes are critical regulators of monoamine-NMDA receptor signaling cross-talk and link these complexes to disorders that manifest as hyperactivity, impaired learning, and motor dysfunctions.
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Affiliation(s)
- Keqiang Xie
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455 USA
| | - Shencheng Ge
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 USA
| | | | - Christy L. Haynes
- Department of Chemistry, University of Minnesota, Minneapolis, MN 55455 USA
| | - Kenneth J. Renner
- Department of Biology, University of South Dakota, Vermillion, SD 57069
| | - Robert L. Meisel
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455 USA
| | - Rafael Lujan
- Departamento de Ciencias Médicas, Facultad de Medicina, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - Kirill A. Martemyanov
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455 USA,Address for correspondence: Dr. Kirill Martemyanov, Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, 3C2, Jupiter, Florida 33458 Phone: (612) 245-7567,
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Membrane attachment is key to protecting transducin GTPase-activating complex from intracellular proteolysis in photoreceptors. J Neurosci 2011; 31:14660-8. [PMID: 21994382 DOI: 10.1523/jneurosci.3516-11.2011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The members of the R7 regulator of G-protein signaling (RGS) protein subfamily are versatile regulators of G-protein signaling throughout the nervous system. Recent studies indicate that they are often found in complexes with membrane anchor proteins that serve as versatile modulators of their activity, intracellular targeting, and stability. One striking example is the interplay between the membrane anchor R9AP and the RGS9-1 · Gβ5 GTPase-activating complex responsible for the rapid inactivation of the G-protein transducin in vertebrate photoreceptor cells during their recovery from light excitation. The amount of this complex in photoreceptors sets their temporal resolution and is precisely regulated by the expression level of R9AP, which serves to protect the RGS9-1 and Gβ5 subunits from intracellular proteolysis. In this study, we investigated the mechanism by which R9AP performs its protective function in mouse rods and found that it is entirely confined to recruiting RGS9-1 · Gβ5 to cellular membranes. Furthermore, membrane attachment of RGS9-1 · Gβ5 is sufficient for its stable expression in rods even in the absence of R9AP. Our second finding is that RGS9-1 · Gβ5 possesses targeting information that specifies its exclusion from the outer segment and that this information is neutralized by association with R9AP to allow outer segment targeting. Finally, we demonstrate that the ability of R9AP · RGS9-1 · Gβ5 to accelerate GTP hydrolysis on transducin is independent of its means of membrane attachment, since replacing the transmembrane domain of R9AP with a site for lipid modification did not impair the catalytic activity of this complex.
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Masuho I, Wakasugi-Masuho H, Posokhova EN, Patton JR, Martemyanov KA. Type 5 G protein beta subunit (Gbeta5) controls the interaction of regulator of G protein signaling 9 (RGS9) with membrane anchors. J Biol Chem 2011; 286:21806-13. [PMID: 21511947 DOI: 10.1074/jbc.m111.241513] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The R7 family of regulators of G protein signaling (RGS) proteins, comprising RGS6, RGS7, RGS9, and RGS11, regulate neuronal G protein signaling pathways. All members of the R7 RGS form trimeric complexes with the atypical G protein β subunit, Gβ5, and membrane anchor R7BP or R9AP. Association with Gβ5 and membrane anchors has been shown to be critical for maintaining proteolytic stability of the R7 RGS proteins. However, despite its functional importance, the mechanism of how R7 RGS forms complexes with Gβ5 and membrane anchors remains poorly understood. Here, we used protein-protein interaction, co-localization, and protein stability assays to show that association of RGS9 with membrane anchors requires Gβ5. We further establish that the recruitment of R7BP to the complex requires an intact interface between the N-terminal lobe of RGS9 and protein interaction surface of Gβ5. Site-directed mutational analysis reveals that distinct molecular determinants in the interface between Gβ5 and N-terminal Dishevelled, EGL-10, Pleckstrin/DEP Helical Extension (DEP/DHEY) domains are differentially involved in R7BP binding and proteolytic stabilization. On the basis of these findings, we conclude that Gβ5 contributes to the formation of the binding site to the membrane anchors and thus is playing a central role in the assembly of the proteolytically stable trimeric complex and its correct localization in the cell.
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Affiliation(s)
- Ikuo Masuho
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, USA
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