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Kim D, Yadav D, Song M. An updated review on animal models to study attention-deficit hyperactivity disorder. Transl Psychiatry 2024; 14:187. [PMID: 38605002 PMCID: PMC11009407 DOI: 10.1038/s41398-024-02893-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/18/2024] [Accepted: 03/25/2024] [Indexed: 04/13/2024] Open
Abstract
Attention-deficit hyperactivity disorder (ADHD) is a neuropsychiatric disorder affecting both children and adolescents. Individuals with ADHD experience heterogeneous problems, such as difficulty in attention, behavioral hyperactivity, and impulsivity. Recent studies have shown that complex genetic factors play a role in attention-deficit hyperactivity disorders. Animal models with clear hereditary traits are crucial for studying the molecular, biological, and brain circuit mechanisms underlying ADHD. Owing to their well-managed genetic origins and the relative simplicity with which the function of neuronal circuits is clearly established, models of mice can help learn the mechanisms involved in ADHD. Therefore, in this review, we highlighting the important genetic animal models that can be used to study ADHD.
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Affiliation(s)
- Daegeon Kim
- Department of Life Science, Yeungnam University, Gyeongsan-si, South Korea
| | - Dhananjay Yadav
- Department of Life Science, Yeungnam University, Gyeongsan-si, South Korea
| | - Minseok Song
- Department of Life Science, Yeungnam University, Gyeongsan-si, South Korea.
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Custodio RJP, Kim M, Chung YC, Kim BN, Kim HJ, Cheong JH. Thrsp Gene and the ADHD Predominantly Inattentive Presentation. ACS Chem Neurosci 2023; 14:573-589. [PMID: 36716294 DOI: 10.1021/acschemneuro.2c00710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
There are three presentations of attention-deficit/hyperactivity disorder (ADHD): the predominantly inattention (ADHD-PI), predominantly hyperactive-impulsive (ADHD-HI), and combined (ADHD-C) presentations of ADHD. These may represent distinct childhood-onset neurobehavioral disorders with separate etiologies. ADHD diagnoses are behaviorally based, so investigations into potential etiologies should be founded on behavior. Animal models of ADHD demonstrate face, predictive, and construct validity when they accurately reproduce elements of the symptoms, etiology, biochemistry, and disorder treatment. Spontaneously hypertensive rats (SHR/NCrl) fulfill many validation criteria and compare well with clinical cases of ADHD-C. Compounding the difficulty of selecting an ideal model to study specific presentations of ADHD is a simple fact that our knowledge regarding ADHD neurobiology is insufficient. Accordingly, the current review has explored a potential animal model for a specific presentation, ADHD-PI, with acceptable face, predictive, and construct validity. The Thrsp gene could be a biomarker for ADHD-PI presentation, and THRSP OE mice could represent an animal model for studying this distinct ADHD presentation.
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Affiliation(s)
- Raly James Perez Custodio
- Department of Ergonomics, Leibniz Research Centre for Working Environment and Human Factors─IfADo, Ardeystraße 67, 44139 Dortmund, Germany
| | - Mikyung Kim
- Department of Chemistry & Life Science, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul 01795, Republic of Korea.,Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarangro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Young-Chul Chung
- Department of Psychiatry, Jeonbuk National University Medical School, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea
| | - Bung-Nyun Kim
- Department of Psychiatry and Behavioral Science, College of Medicine, Seoul National University, 101 Daehakro, Jongno-gu, Seoul 03080, Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarangro, Nowon-gu, Seoul 01795, Republic of Korea
| | - Jae Hoon Cheong
- Institute for New Drug Development, School of Pharmacy, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Republic of Korea
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Klocke B, Krone K, Tornes J, Moore C, Ott H, Pitychoutis PM. Insights into the role of intracellular calcium signaling in the neurobiology of neurodevelopmental disorders. Front Neurosci 2023; 17:1093099. [PMID: 36875674 PMCID: PMC9975342 DOI: 10.3389/fnins.2023.1093099] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
Calcium (Ca2+) comprises a critical ionic second messenger in the central nervous system that is under the control of a wide array of regulatory mechanisms, including organellar Ca2+ stores, membrane channels and pumps, and intracellular Ca2+-binding proteins. Not surprisingly, disturbances in Ca2+ homeostasis have been linked to neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. However, aberrations in Ca2+ homeostasis have also been implicated in neuropsychiatric disorders with a strong neurodevelopmental component including autism spectrum disorder (ASD) attention-deficit hyperactivity disorder (ADHD) and schizophrenia (SCZ). While plasma membrane Ca2+ channels and synaptic Ca2+-binding proteins have been extensively studied, increasing evidence suggests a prominent role for intracellular Ca2+ stores, such as the endoplasmic reticulum (ER), in aberrant neurodevelopment. In the context of the current mini-review, we discuss recent findings implicating critical intracellular Ca2+-handling regulators such as the sarco-ER Ca2+ ATPase 2 (SERCA2), ryanodine receptors (RyRs), inositol triphosphate receptors (IP3Rs), and parvalbumin (PVALB), in the emergence of ASD, SCZ, and ADHD.
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Affiliation(s)
- Benjamin Klocke
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Kylie Krone
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Jason Tornes
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Carter Moore
- Department of Biology, University of Dayton, Dayton, OH, United States
| | - Hayden Ott
- Department of Biology, University of Dayton, Dayton, OH, United States
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De Nittis P, Efthymiou S, Sarre A, Guex N, Chrast J, Putoux A, Sultan T, Raza Alvi J, Ur Rahman Z, Zafar F, Rana N, Rahman F, Anwar N, Maqbool S, Zaki MS, Gleeson JG, Murphy D, Galehdari H, Shariati G, Mazaheri N, Sedaghat A, Lesca G, Chatron N, Salpietro V, Christoforou M, Houlden H, Simonds WF, Pedrazzini T, Maroofian R, Reymond A. Inhibition of G-protein signalling in cardiac dysfunction of intellectual developmental disorder with cardiac arrhythmia (IDDCA) syndrome. J Med Genet 2021; 58:815-831. [PMID: 33172956 PMCID: PMC8639930 DOI: 10.1136/jmedgenet-2020-107015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 08/30/2020] [Accepted: 09/04/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pathogenic variants of GNB5 encoding the β5 subunit of the guanine nucleotide-binding protein cause IDDCA syndrome, an autosomal recessive neurodevelopmental disorder associated with cognitive disability and cardiac arrhythmia, particularly severe bradycardia. METHODS We used echocardiography and telemetric ECG recordings to investigate consequences of Gnb5 loss in mouse. RESULTS We delineated a key role of Gnb5 in heart sinus conduction and showed that Gnb5-inhibitory signalling is essential for parasympathetic control of heart rate (HR) and maintenance of the sympathovagal balance. Gnb5-/- mice were smaller and had a smaller heart than Gnb5+/+ and Gnb5+/- , but exhibited better cardiac function. Lower autonomic nervous system modulation through diminished parasympathetic control and greater sympathetic regulation resulted in a higher baseline HR in Gnb5-/- mice. In contrast, Gnb5-/- mice exhibited profound bradycardia on treatment with carbachol, while sympathetic modulation of the cardiac stimulation was not altered. Concordantly, transcriptome study pinpointed altered expression of genes involved in cardiac muscle contractility in atria and ventricles of knocked-out mice. Homozygous Gnb5 loss resulted in significantly higher frequencies of sinus arrhythmias. Moreover, we described 13 affected individuals, increasing the IDDCA cohort to 44 patients. CONCLUSIONS Our data demonstrate that loss of negative regulation of the inhibitory G-protein signalling causes HR perturbations in Gnb5-/- mice, an effect mainly driven by impaired parasympathetic activity. We anticipate that unravelling the mechanism of Gnb5 signalling in the autonomic control of the heart will pave the way for future drug screening.
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Affiliation(s)
| | - Stephanie Efthymiou
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Alexandre Sarre
- Cardiovascular Assessment Facility, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Guex
- Bioinformatics Competence Center, University of Lausanne, Lausanne, Switzerland
| | - Jacqueline Chrast
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Audrey Putoux
- Service de Génétique, Hopital Femme Mere Enfant, Bron, France
| | - Tipu Sultan
- Department of Pediatric Neurology, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Javeria Raza Alvi
- Department of Pediatric Neurology, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Zia Ur Rahman
- Department of Pediatric Neurology, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Faisal Zafar
- Department of Paediatric Neurology, Children's Hospital and Institute of Child Health, Multan, Pakistan
| | - Nuzhat Rana
- Department of Paediatric Neurology, Children's Hospital and Institute of Child Health, Multan, Pakistan
| | - Fatima Rahman
- Department of Developmental-Behavioural Paediatrics, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Najwa Anwar
- Department of Developmental-Behavioural Paediatrics, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Shazia Maqbool
- Department of Developmental-Behavioural Paediatrics, The Children's Hospital and Institute of Child Health, Lahore, Pakistan
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo, Egypt
| | - Joseph G Gleeson
- Department of Neuroscience and Pediatrics, Howard Hughes Medical Institute, La Jolla, California, USA
| | - David Murphy
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Hamid Galehdari
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahwaz, Iran (the Islamic Republic of)
| | - Gholamreza Shariati
- Department of Medical Genetics, Faculty of Medicine, Ahvaz Jondishapour University of Medical Sciences, Ahvaz, Iran (the Islamic Republic of)
| | - Neda Mazaheri
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahwaz, Iran (the Islamic Republic of)
| | - Alireza Sedaghat
- Health Research Institute, Diabetes Research Center, Ahvaz Jundishapur University of medical Sciences, Ahvaz, Iran (the Islamic Republic of)
| | - Gaetan Lesca
- Service de Genetique, Hospices Civils de Lyon, Lyon, France
| | - Nicolas Chatron
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
- Service de Genetique, Hospices Civils de Lyon, Lyon, France
| | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Marilena Christoforou
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Henry Houlden
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - William F Simonds
- Metabolic Diseases Branch/NIDDK, National Institutes of Health, Bethesda, MD, USA
| | - Thierry Pedrazzini
- Experimental Cardiology Unit, Department of Cardiovascular Medicine, University of Lausanne, Lausanne, Switzerland
| | - Reza Maroofian
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, UK
| | - Alexandre Reymond
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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Extended Phenotyping and Functional Validation Facilitate Diagnosis of a Complex Patient Harboring Genetic Variants in MCCC1 and GNB5 Causing Overlapping Phenotypes. Genes (Basel) 2021; 12:genes12091352. [PMID: 34573334 PMCID: PMC8469011 DOI: 10.3390/genes12091352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/22/2022] Open
Abstract
Identifying multiple ultra-rare genetic syndromes with overlapping phenotypes is a diagnostic conundrum in clinical genetics. This study investigated the pathogenicity of a homozygous missense variant in GNB5 (GNB5L; NM_016194.4: c.920T > G (p. Leu307Arg); GNB5S; NM_006578.4: c.794T > G (p. Leu265Arg)) identified through exome sequencing in a female child who also had 3-methylcrotonyl-CoA carboxylase (3-MCC) deficiency (newborn screening positive) and hemoglobin E trait. The proband presented with early-onset intellectual disability, the severity of which was more in keeping with GNB5-related disorder than 3-MCC deficiency. She later developed bradycardia and cardiac arrest, and upon re-phenotyping showed cone photo-transduction recovery deficit, all known only to GNB5-related disorders. Patient-derived fibroblast assays showed preserved GNB5S expression, but bioluminescence resonance energy transfer assay showed abolished function of the variant reconstituted Gβ5S containing RGS complexes for deactivation of D2 dopamine receptor activity, confirming variant pathogenicity. This study highlights the need for precise phenotyping and functional assays to facilitate variant classification and clinical diagnosis in patients with complex medical conditions.
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Masuho I, Balaji S, Muntean BS, Skamangas NK, Chavali S, Tesmer JJG, Babu MM, Martemyanov KA. A Global Map of G Protein Signaling Regulation by RGS Proteins. Cell 2020; 183:503-521.e19. [PMID: 33007266 PMCID: PMC7572916 DOI: 10.1016/j.cell.2020.08.052] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 07/03/2020] [Accepted: 08/29/2020] [Indexed: 12/24/2022]
Abstract
The control over the extent and timing of G protein signaling is provided by the regulator of G protein signaling (RGS) proteins that deactivate G protein α subunits (Gα). Mammalian genomes encode 20 canonical RGS and 16 Gα genes with key roles in physiology and disease. To understand the principles governing the selectivity of Gα regulation by RGS, we examine the catalytic activity of all canonical human RGS proteins and their selectivity for a complete set of Gα substrates using real-time kinetic measurements in living cells. The data reveal rules governing RGS-Gα recognition, the structural basis of its selectivity, and provide principles for engineering RGS proteins with defined selectivity. The study also explores the evolution of RGS-Gα selectivity through ancestral reconstruction and demonstrates how naturally occurring non-synonymous variants in RGS alter signaling. These results provide a blueprint for decoding signaling selectivity and advance our understanding of molecular recognition principles. Systematic analysis reveals G protein selectivity of all canonical RGS proteins RGS proteins rely on selectivity bar codes for selective G protein recognition Transplantation of bar codes across RGS proteins switches their G protein preferences Natural variants, mutations, and evolution shape RGS selectivity
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Affiliation(s)
- Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Santhanam Balaji
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Departments of Structural Biology and Center for Data Driven Discovery, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Brian S Muntean
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Nickolas K Skamangas
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA
| | - Sreenivas Chavali
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Department of Biology, Indian Institute of Science Education and Research (IISER) Tirupati, Karakambadi Road, Tirupati 517 507, India
| | - John J G Tesmer
- Departments of Biological Sciences and Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907-2054, USA
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK; Departments of Structural Biology and Center for Data Driven Discovery, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute Florida, Jupiter, FL 33458, USA.
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Regulators of G protein signalling as pharmacological targets for the treatment of neuropathic pain. Pharmacol Res 2020; 160:105148. [PMID: 32858121 DOI: 10.1016/j.phrs.2020.105148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 07/24/2020] [Accepted: 08/10/2020] [Indexed: 12/30/2022]
Abstract
Neuropathic pain, a specific type of chronic pain resulting from persistent nervous tissue lesions, is a debilitating condition that affects about 7% of the population. This condition remains particularly difficult to treat because of the poor understanding of its underlying mechanisms. Drugs currently used to alleviate this chronic pain syndrome are of limited benefit due to their lack of efficacy and the elevated risk of side effects, especially after a prolonged period of treatment. Although drugs targeting G protein-coupled receptors (GPCR) also have several limitations, such as progressive loss of efficacy due to receptor desensitization or unavoidable side effects due to wide receptor distribution, the identification of several molecular partners that contribute to the fine-tuning of receptor activity has raised new opportunities for the development of alternative therapeutic approaches. Regulators of G protein signalling (RGS) act intracellularly by influencing the coupling process and activity of G proteins, and are amongst the best-characterized physiological modulators of GPCR. Changes in RGS expression have been documented in a range of models of neuropathic pain, or after prolonged treatment with diverse analgesics, and could participate in altered pain processing as well as impaired physiological or pharmacological control of nociceptive signals. The present review summarizes the experimental data that implicates RGS in the development of pain with focus on the pathological mechanisms of neuropathic pain, including the impact of neuropathic lesions on RGS expression and, reciprocally, the influence of modifying RGS on GPCRs involved in the modulation of nociception as well as on the outcome of pain. In this context, we address the question of the relevance of RGS as promising targets in the treatment of neuropathic pain.
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Li M, Zhang W, Zhou X. Identification of genes involved in the evolution of human intelligence through combination of inter-species and intra-species genetic variations. PeerJ 2020; 8:e8912. [PMID: 32337102 PMCID: PMC7167246 DOI: 10.7717/peerj.8912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 03/15/2020] [Indexed: 11/20/2022] Open
Abstract
Understanding the evolution of human intelligence is an important undertaking in the science of human genetics. A great deal of biological research has been conducted to search for genes which are related to the significant increase in human brain volume and cerebral cortex complexity during hominid evolution. However, genetic changes affecting intelligence in hominid evolution have remained elusive. We supposed that a subset of intelligence-related genes, which harbored intra-species variations in human populations, may also be evolution-related genes which harbored inter-species variations between humans (Homo sapiens) and great apes (including Pan troglodytes and Pongo abelii). Here we combined inter-species and intra-species genetic variations to discover genes involved in the evolution of human intelligence. Information was collected from published GWAS works on intelligence and a total of 549 genes located within the intelligence-associated loci were identified. The intelligence-related genes containing human-specific variations were detected based on the latest high-quality genome assemblies of three human's closest species. Finally, we identified 40 strong candidates involved in human intelligence evolution. Expression analysis using RNA-Seq data revealed that most of the genes displayed a relatively high expression in the cerebral cortex. For these genes, there is a distinct expression pattern between humans and other species, especially in neocortex tissues. Our work provided a list of strong candidates for the evolution of human intelligence, and also implied that some intelligence-related genes may undergo inter-species evolution and contain intra-species variation.
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Affiliation(s)
- Mengjie Li
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Wenting Zhang
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Xiaoyi Zhou
- College of Life Sciences, Shanghai Normal University, Shanghai, China
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Malerba N, De Nittis P, Merla G. The Emerging Role of Gβ Subunits in Human Genetic Diseases. Cells 2019; 8:E1567. [PMID: 31817184 PMCID: PMC6952978 DOI: 10.3390/cells8121567] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 11/23/2019] [Accepted: 11/29/2019] [Indexed: 12/20/2022] Open
Abstract
Environmental stimuli are perceived and transduced inside the cell through the activation of signaling pathways. One common type of cell signaling transduction network is initiated by G-proteins. G-proteins are activated by G-protein-coupled receptors (GPCRs) and transmit signals from hormones, neurotransmitters, and other signaling factors, thus controlling a number of biological processes that include synaptic transmission, visual photoreception, hormone and growth factors release, regulation of cell contraction and migration, as well as cell growth and differentiation. G-proteins mainly act as heterotrimeric complexes, composed of alpha, beta, and gamma subunits. In the last few years, whole exome sequencing and biochemical studies have shown causality of disease-causing variants in genes encoding G-proteins and human genetic diseases. This review focuses on the G-protein β subunits and their emerging role in the etiology of genetically inherited rare diseases in humans.
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Affiliation(s)
- Natascia Malerba
- Division of Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, Viale Cappuccini, 71013 San Giovanni Rotondo (FG), Italy;
| | - Pasquelena De Nittis
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland;
| | - Giuseppe Merla
- Division of Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, Viale Cappuccini, 71013 San Giovanni Rotondo (FG), Italy;
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10
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Muntean BS, Patil DN, Madoux F, Fossetta J, Scampavia L, Spicer TP, Martemyanov KA. A High-Throughput Time-Resolved Fluorescence Energy Transfer Assay to Screen for Modulators of RGS7/Gβ5/R7BP Complex. Assay Drug Dev Technol 2019; 16:150-161. [PMID: 29658790 DOI: 10.1089/adt.2017.839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are excellent drug targets exploited by majority of the Food and Drug Administration-approved medications, but when modulated, are often accompanied by significant adverse effects. Targeting of other elements in GPCR pathways for improved safety and efficacy is thus an unmet need. The strength of GPCR signaling is tightly regulated by regulators of G protein signaling (RGS) proteins, making them attractive drug targets. We focused on a prominent RGS complex in the brain consisting of RGS7 and its binding partners Gβ5 and R7BP. These complexes play critical roles in regulating multiple GPCRs and essential physiological processes, yet no small molecule modulators are currently available to modify its function. In this study, we report a novel high-throughput approach to screen for small molecule modulators of the intramolecular transitions in the RGS7/Gβ5/R7BP complex known to be involved in its allosteric regulation. We developed a time-resolved fluorescence energy transfer-based in vitro assay that utilizes full-length recombinant proteins and shows consistency, excellent assay statistics, and high level of sensitivity. We demonstrated the potential of this approach by screening two compound libraries (LOPAC 1280 and MicroSource Spectrum). This study confirms the feasibility of the chosen strategy for identifying small molecule modulators of RGS7/Gβ5/R7BP complex for impacting signaling downstream of the GPCRs.
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Affiliation(s)
- Brian S Muntean
- 1 Department of Neuroscience, The Scripps Research Institute , Jupiter, Florida
| | - Dipak N Patil
- 1 Department of Neuroscience, The Scripps Research Institute , Jupiter, Florida
| | - Franck Madoux
- 2 Department of Molecular Medicine, The Scripps Research Institute , Jupiter, Florida
| | | | - Louis Scampavia
- 2 Department of Molecular Medicine, The Scripps Research Institute , Jupiter, Florida
| | - Timothy P Spicer
- 2 Department of Molecular Medicine, The Scripps Research Institute , Jupiter, Florida
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11
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Luo Z, Ahlers-Dannen KE, Spicer MM, Yang J, Alberico S, Stevens HE, Narayanan NS, Fisher RA. Age-dependent nigral dopaminergic neurodegeneration and α-synuclein accumulation in RGS6-deficient mice. JCI Insight 2019; 5:126769. [PMID: 31120439 DOI: 10.1172/jci.insight.126769] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Parkinson's is primarily a non-familial, age-related disorder caused by α-synuclein accumulation and the progressive loss of dopamine neurons in the substantia nigra pars compacta (SNc). G protein-coupled receptor (GPCR)-cAMP signaling has been linked to a reduction in human Parkinson's incidence and α-synuclein expression. Neuronal cAMP levels are controlled by GPCRs coupled to Gs or Gi/o, which increase or decrease cAMP, respectively. Regulator of G protein signaling 6 (RGS6) powerfully inhibits Gi/o signaling. Therefore, we hypothesized that RGS6 suppresses D2 autoreceptor- Gi/o signaling in SNc dopamine neurons promoting neuronal survival and reducing α-synuclein expression. Here we provide novel evidence that RGS6 critically suppresses late-age-onset SNc dopamine neuron loss and α-synuclein accumulation. RGS6 is restrictively expressed in human SNc dopamine neurons and, despite their loss in Parkinson's, all surviving neurons express RGS6. RGS6-/- mice exhibit hyperactive D2 autoreceptors with reduced cAMP signaling in SNc dopamine neurons. Importantly, RGS6-/- mice recapitulate key sporadic Parkinson's hallmarks, including: SNc dopamine neuron loss, reduced nigrostriatal dopamine, motor deficits, and α-synuclein accumulation. To our knowledge, Rgs6 is the only gene whose loss phenocopies these features of human Parkinson's. Therefore, RGS6 is a key regulator of D2R-Gi/o signaling in SNc dopamine neurons, protecting against Parkinson's neurodegeneration and α-synuclein accumulation.
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Affiliation(s)
- Zili Luo
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Katelin E Ahlers-Dannen
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Mackenzie M Spicer
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.,Interdisciplinary Graduate Program of Molecular Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Jianqi Yang
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | | | - Hanna E Stevens
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Nandakumar S Narayanan
- Department of Neurology, 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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Malerba N, Towner S, Keating K, Squeo GM, Wilson W, Merla G. A NGS-Targeted Autism/ID Panel Reveals Compound Heterozygous GNB5 Variants in a Novel Patient. Front Genet 2018; 9:626. [PMID: 30631341 PMCID: PMC6315145 DOI: 10.3389/fgene.2018.00626] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 11/23/2018] [Indexed: 11/13/2022] Open
Abstract
Homozygous and compound heterozygous pathogenic variants in GNB5 have been recently associated with a spectrum of clinical presentations varying from a severe multisystem form of the disorder including intellectual disability, early infantile developmental and epileptic encephalopathy, retinal abnormalities and cardiac arrhythmias (IDDCA) to a milder form with language delay, attention-deficit/hyperactivity disorder, cognitive impairment, with or without cardiac arrhythmia (LADCI). Approximately twenty patients have been described so far; here we report a novel case of a 2.5-year-old female who is a compound heterozygote for a frameshift and a missense variant in the GNB5 gene. Her clinical presentation is consistent with a moderate phenotype, corroborating the direct correlation between the type and pathogenic mechanism of the GNB5 genetic variant and the severity of related phenotype.
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Affiliation(s)
- Natascia Malerba
- Division of Medical Genetics, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - Shelley Towner
- Division of Medical Genetics, University of Virginia, Charlottesville, VA, United States
| | - Katherine Keating
- Division of Medical Genetics, University of Virginia, Charlottesville, VA, United States
| | - Gabriella Maria Squeo
- Division of Medical Genetics, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
| | - William Wilson
- Division of Medical Genetics, University of Virginia, Charlottesville, VA, United States
| | - Giuseppe Merla
- Division of Medical Genetics, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Italy
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13
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Kang N, Kang JY, Park S, Shin DM. Increased store-operated Ca 2+ entry mediated by GNB5 and STIM1. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2018; 22:343-348. [PMID: 29719456 PMCID: PMC5928347 DOI: 10.4196/kjpp.2018.22.3.343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/14/2018] [Accepted: 02/19/2018] [Indexed: 01/27/2023]
Abstract
Recent human genetic studies have shown that Gβ5 is related to various clinical symptoms, such as sinus bradycardia, cognitive disability, and attention deficit hyperactivity disorder. Although the calcium signaling cascade is closely associated with a heterotrimeric G-protein, the function of Gβ5 in calcium signaling and its relevance to clinical symptoms remain unknown. In this study, we investigated the in vitro changes of store-operated calcium entry (SOCE) with exogenous expression of Gβ5. The cells expressing Gβ5 had enhanced SOCE after depletion of calcium ion inside the endoplasmic reticulum. Gβ5 also augmented Stim1- and Orai1-dependent SOCE. An ORAI1 loss-of-function mutant did not show inhibition of Gβ5-induced SOCE, and a STIM1-ERM truncation mutant showed no enhancement of SOCE. These results suggested a novel role of GNB5 and Stim1, and provided insight into the regulatory mechanism of SOCE.
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Affiliation(s)
- Namju Kang
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Jung Yun Kang
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Soonhong Park
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
| | - Dong Min Shin
- Department of Oral Biology, BK21 PLUS Project, Yonsei University College of Dentistry, Seoul 03722, Korea
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14
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Chakraborti S, Pramanick A, Saha S, Roy SS, Chaudhuri AR, Das M, Ghosh S, Stewart A, Maity B. Atypical G Protein β5 Promotes Cardiac Oxidative Stress, Apoptosis, and Fibrotic Remodeling in Response to Multiple Cancer Chemotherapeutics. Cancer Res 2017; 78:528-541. [DOI: 10.1158/0008-5472.can-17-1280] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 09/08/2017] [Accepted: 11/13/2017] [Indexed: 11/16/2022]
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15
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Wang Q, Pronin AN, Levay K, Almaca J, Fornoni A, Caicedo A, Slepak VZ. Regulator of G-protein signaling Gβ5-R7 is a crucial activator of muscarinic M3 receptor-stimulated insulin secretion. FASEB J 2017; 31:4734-4744. [PMID: 28687610 DOI: 10.1096/fj.201700197rr] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/27/2017] [Indexed: 12/20/2022]
Abstract
In pancreatic β cells, muscarinic cholinergic receptor M3 (M3R) stimulates glucose-induced secretion of insulin. Regulator of G-protein signaling (RGS) proteins are critical modulators of GPCR activity, yet their role in β cells remains largely unknown. R7 subfamily RGS proteins are stabilized by the G-protein subunit Gβ5, such that the knockout of the Gnb5 gene results in degradation of all R7 subunits. We found that Gnb5 knockout in mice or in the insulin-secreting MIN6 cell line almost completely eliminates insulinotropic activity of M3R. Moreover, overexpression of Gβ5-RGS7 strongly promotes M3R-stimulated insulin secretion. Examination of this noncanonical mechanism in Gnb5-/- MIN6 cells showed that cAMP, diacylglycerol, or Ca2+ levels were not significantly affected. There was no reduction in the amplitude of free Ca2+ responses in islets from the Gnb5-/- mice, but the frequency of Ca2+ oscillations induced by cholinergic agonist was lowered by more than 30%. Ablation of Gnb5 impaired M3R-stimulated phosphorylation of ERK1/2. Stimulation of the ERK pathway in Gnb5-/- cells by epidermal growth factor restored M3R-stimulated insulin release to near normal levels. Identification of the novel role of Gβ5-R7 in insulin secretion may lead to a new therapeutic approach for improving pancreatic β-cell function.-Wang, Q., Pronin, A. N., Levay, K., Almaca, J., Fornoni, A., Caicedo, A., Slepak, V. Z. Regulator of G-protein signaling Gβ5-R7 is a crucial activator of muscarinic M3 receptor-stimulated insulin secretion.
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Affiliation(s)
- Qiang Wang
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA; and
| | - Alexey N Pronin
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA; and
| | - Konstantin Levay
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA; and
| | - Joana Almaca
- Department of Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Alessia Fornoni
- Department of Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Alejandro Caicedo
- Department of Medicine, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA
| | - Vladlen Z Slepak
- Department of Molecular and Cellular Pharmacology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, USA; and
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de la Peña JB, Dela Peña IJ, Custodio RJ, Botanas CJ, Kim HJ, Cheong JH. Exploring the Validity of Proposed Transgenic Animal Models of Attention-Deficit Hyperactivity Disorder (ADHD). Mol Neurobiol 2017; 55:3739-3754. [PMID: 28534274 DOI: 10.1007/s12035-017-0608-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 05/09/2017] [Indexed: 12/31/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a common, behavioral, and heterogeneous neurodevelopmental condition characterized by hyperactivity, impulsivity, and inattention. Symptoms of this disorder are managed by treatment with methylphenidate, amphetamine, and/or atomoxetine. The cause of ADHD is unknown, but substantial evidence indicates that this disorder has a significant genetic component. Transgenic animals have become an essential tool in uncovering the genetic factors underlying ADHD. Although they cannot accurately reflect the human condition, they can provide insights into the disorder that cannot be obtained from human studies due to various limitations. An ideal animal model of ADHD must have face (similarity in symptoms), predictive (similarity in response to treatment or medications), and construct (similarity in etiology or underlying pathophysiological mechanism) validity. As the exact etiology of ADHD remains unclear, the construct validity of animal models of ADHD would always be limited. The proposed transgenic animal models of ADHD have substantially increased and diversified over the years. In this paper, we compiled and explored the validity of proposed transgenic animal models of ADHD. Each of the reviewed transgenic animal models has strengths and limitations. Some fulfill most of the validity criteria of an animal model of ADHD and have been extensively used, while there are others that require further validation. Nevertheless, these transgenic animal models of ADHD have provided and will continue to provide valuable insights into the genetic underpinnings of this complex disorder.
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Affiliation(s)
- June Bryan de la Peña
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Irene Joy Dela Peña
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Raly James Custodio
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Chrislean Jun Botanas
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Hee Jin Kim
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea
| | - Jae Hoon Cheong
- Uimyung Research Institute for Neuroscience, Department of Pharmacy, Sahmyook University, 815 Hwarang-ro, Nowon-gu, Seoul, 01795, Republic of Korea.
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17
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Aguado C, Orlandi C, Fajardo-Serrano A, Gil-Minguez M, Martemyanov KA, Luján R. Cellular and Subcellular Localization of the RGS7/Gβ5/R7BP Complex in the Cerebellar Cortex. Front Neuroanat 2016; 10:114. [PMID: 27965545 PMCID: PMC5127842 DOI: 10.3389/fnana.2016.00114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 11/10/2016] [Indexed: 11/13/2022] Open
Abstract
A member of regulator of G-protein signaling family, RGS7, is an essential modulator of signaling through GABAB receptors. RGS7 functions as a macromolecular complex with type 5 G protein β (Gβ5) and R7 binding protein (R7BP) to control the localization and function of the resultant heterotrimeric complexes. Here, we used co-immunoprecipitation, in situ hybridization, histoblot and immunohistochemical techniques at the light and electron microscopic level to advance understanding of RGS7-Gβ5-R7BP complexes in the central nervous system, focusing on distinct neuronal populations in the cerebellar cortex. Histoblot analysis showed that RGS7, Gβ5 and R7BP proteins were widely expressed in the brain, with mostly an overlapping pattern and showing a high expression level in the molecular layer of the cerebellar cortex. Co-immunoprecipitation experiments established that the RGS7/Gβ5 forms complexes with R7BP in the cerebellum. At the cellular level, RGS7 and R7BP mRNAs were expressed at the highest level in Purkinje cells (PCs) and Golgi cells, and at low levels in granule cells. Immunohistochemistry confirmed that labeling for RGS7, Gβ5 and R7BP were present in the three neuronal populations and concentrated in dendrites and spines. At the electron microscopic level, immunolabeling for RGS7, Gβ5 and R7BP proteins was found both at postsynaptic and presynaptic sites and showed similar distribution patterns. Immunoreactivity for the three proteins was mostly localized along the extrasynaptic plasma membrane of dendritic shafts and spines of PCs and to a lesser extent, in axon terminals (AT) establishing excitatory synapses. Quantitative analysis of immunogold particles for RGS7, Gβ5 and R7BP revealed that they are non-uniformly distributed along the surface of PCs, and show enrichment around excitatory synapses on dendritic spines. We further report that deletion of R7BP in mice reduced the targeting of both RGS7 and Gβ5 to the plasma membrane. Altogether, these data support the existence of macromolecular complexes composed of RGS7-Gβ5-R7BP in PCs. The location at post- and pre-synaptic sites in PCs spines-parallel fiber synapses suggests their involvement in the modulation of glutamatergic neurotransmission in the cerebellar cortex.
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Affiliation(s)
- Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | - Cesare Orlandi
- Department of Neuroscience, The Scripps Research Institute Jupiter, FL, USA
| | - Ana Fajardo-Serrano
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | - Mercedes Gil-Minguez
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
| | | | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Spain
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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: 31] [Impact Index Per Article: 3.9] [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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Salaga M, Storr M, Martemyanov KA, Fichna J. RGS proteins as targets in the treatment of intestinal inflammation and visceral pain: New insights and future perspectives. Bioessays 2016; 38:344-54. [PMID: 26817719 PMCID: PMC4916644 DOI: 10.1002/bies.201500118] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Regulators of G protein signaling (RGS) proteins provide timely termination of G protein-coupled receptor (GPCR) responses. Serving as a central control point in GPCR signaling cascades, RGS proteins are promising targets for drug development. In this review, we discuss the involvement of RGS proteins in the pathophysiology of the gastrointestinal inflammation and their potential to become a target for anti-inflammatory drugs. Specifically, we evaluate the emerging evidence for modulation of selected receptor families: opioid, cannabinoid and serotonin by RGS proteins. We discuss how the regulation of RGS protein level and activity may modulate immunological pathways involved in the development of intestinal inflammation. Finally, we propose that RGS proteins may serve as a prognostic factor for survival rate in colorectal cancer. The ideas introduced in this review set a novel conceptual framework for the utilization of RGS proteins in the treatment of gastrointestinal inflammation, a growing major concern worldwide.
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Affiliation(s)
- Maciej Salaga
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Poland
| | - Martin Storr
- Walter Brendel Center of Experimental Medicine, University of Munich, Germany
| | - Kirill A. Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL, USA
- Corresponding authors: J.F. Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland, Phone: ++48 42 272 57 07, Fax: ++48 42 272 56 94, . K.A.M., Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way C347, Jupiter, FL 33458, USA, Phone: ++1 561 228 2770,
| | - Jakub Fichna
- Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Poland
- Corresponding authors: J.F. Department of Biochemistry, Faculty of Medicine, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland, Phone: ++48 42 272 57 07, Fax: ++48 42 272 56 94, . K.A.M., Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way C347, Jupiter, FL 33458, USA, Phone: ++1 561 228 2770,
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Wilmot B, Fry R, Smeester L, Musser ED, Mill J, Nigg JT. Methylomic analysis of salivary DNA in childhood ADHD identifies altered DNA methylation in VIPR2. J Child Psychol Psychiatry 2016; 57:152-60. [PMID: 26304033 PMCID: PMC4724325 DOI: 10.1111/jcpp.12457] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/06/2015] [Indexed: 12/22/2022]
Abstract
BACKGROUND Peripheral epigenetic marks hold promise for understanding psychiatric illness and may represent fingerprints of gene-environment interactions. We conducted an initial examination of CpG methylation variation in children with or without attention-deficit/hyperactivity disorder (ADHD). METHODS Children age 7-12 were recruited, screened, evaluated and assigned to ADHD or non-ADHD groups by defined research criteria. Two independent age-matched samples were examined, a discovery set (n = 92, all boys, half control, half ADHD) and a confirmation set (n = 20, half ADHD, all boys). 5-methylcytosine levels were quantified in salivary DNA using the Illumina 450 K HumanMethylation array. Genes for which multiple probes were nominally significant and had a beta difference of at least 2% were evaluated for biological relevance and prioritized for confirmation and sequence validation. Gene pathways were explored and described. RESULTS Two genes met the criteria for confirmation testing, VIPR2 and MYT1L; both had multiple probes meeting cutoffs and strong biological relevance. Probes on VIPR2 passed FDR correction in the confirmation set and were confirmed through bisulfite sequencing. Enrichment analysis suggested involvement of gene sets or pathways related to inflammatory processes and modulation of monoamine and cholinergic neurotransmission. CONCLUSIONS Although it is unknown to what extent CpG methylation seen in peripheral tissue reflect transcriptomic changes in the brain, these initial results indicate that peripheral DNA methylation markers in ADHD may be promising and suggest targeted hypotheses for future study in larger samples.
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Affiliation(s)
- Beth Wilmot
- Division of Psychology, Oregon Health & Science University, Portland, OR
| | - Rebecca Fry
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC
| | - Lisa Smeester
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC
| | - Erica D. Musser
- Department of Psychology, Florida International University, Miami, FL, USA
| | - Jonathan Mill
- University of Exeter Medical School, Exeter University, Exeter,Institute of Psychiatry, Psychology & Neuroscience, King’s College London, London, UK
| | - Joel T. Nigg
- Division of Psychology, Oregon Health & Science University, Portland, OR
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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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22
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Regulator of G protein signaling 6 is a critical mediator of both reward-related behavioral and pathological responses to alcohol. Proc Natl Acad Sci U S A 2015; 112:E786-95. [PMID: 25646431 DOI: 10.1073/pnas.1418795112] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Alcohol is the most commonly abused drug worldwide, and chronic alcohol consumption is a major etiological factor in the development of multiple pathological sequelae, including alcoholic cardiomyopathy and hepatic cirrhosis. Here, we identify regulator of G protein signaling 6 (RGS6) as a critical regulator of both alcohol-seeking behaviors and the associated cardiac and hepatic morbidities through two mechanistically divergent signaling actions. RGS6(-/-) mice consume less alcohol when given free access and are less susceptible to alcohol-induced reward and withdrawal. Antagonism of GABA(B) receptors or dopamine D2 receptors partially reversed the reduction in alcohol consumption in RGS6(-/-) animals. Strikingly, dopamine transporter inhibition completely restored alcohol seeking in mice lacking RGS6. RGS6 deficiency was associated with alterations in the expression of genes controlling dopamine (DA) homeostasis and a reduction in DA levels in the striatum. Taken together, these data implicate RGS6 as an essential regulator of DA bioavailability. RGS6 deficiency also provided dramatic protection against cardiac hypertrophy and fibrosis, hepatic steatosis, and gastrointestinal barrier dysfunction and endotoxemia when mice were forced to consume alcohol. Although RGS proteins canonically function as G-protein regulators, RGS6-dependent, alcohol-mediated toxicity in the heart, liver, and gastrointestinal tract involves the ability of RGS6 to promote reactive oxygen species-dependent apoptosis, an action independent of its G-protein regulatory capacity. We propose that inhibition of RGS6 might represent a viable means to reduce alcohol cravings and withdrawal in human patients, while simultaneously protecting the heart and liver from further damage upon relapse.
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Octeau JC, Schrader JM, Masuho I, Sharma M, Aiudi C, Chen CK, Kovoor A, Celver J. G protein beta 5 is targeted to D2-dopamine receptor-containing biochemical compartments and blocks dopamine-dependent receptor internalization. PLoS One 2014; 9:e105791. [PMID: 25162404 PMCID: PMC4146516 DOI: 10.1371/journal.pone.0105791] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/23/2014] [Indexed: 11/18/2022] Open
Abstract
G beta 5 (Gbeta5, Gβ5) is a unique G protein β subunit that is thought to be expressed as an obligate heterodimer with R7 regulator of G protein signaling (RGS) proteins instead of with G gamma (Gγ) subunits. We found that D2-dopamine receptor (D2R) coexpression enhances the expression of Gβ5, but not that of the G beta 1 (Gβ1) subunit, in HEK293 cells, and that the enhancement of expression occurs through a stabilization of Gβ5 protein. We had previously demonstrated that the vast majority of D2R either expressed endogenously in the brain or exogenously in cell lines segregates into detergent-resistant biochemical fractions. We report that when expressed alone in HEK293 cells, Gβ5 is highly soluble, but is retargeted to the detergent-resistant fraction after D2R coexpression. Furthermore, an in-cell biotin transfer proximity assay indicated that D2R and Gβ5 segregating into the detergent-resistant fraction specifically interacted in intact living cell membranes. Dopamine-induced D2R internalization was blocked by coexpression of Gβ5, but not Gβ1. However, the same Gβ5 coexpression levels had no effect on agonist-induced internalization of the mu opioid receptor (MOR), cell surface D2R levels, dopamine-mediated recruitment of β-arrestin to D2R, the amplitude of D2R-G protein coupling, or the deactivation kinetics of D2R-activated G protein signals. The latter data suggest that the interactions between D2R and Gβ5 are not mediated by endogenously expressed R7 RGS proteins.
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Affiliation(s)
- J. Christopher Octeau
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Joseph M. Schrader
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Meenakshi Sharma
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Christopher Aiudi
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
| | - Ching-Kang Chen
- Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Abraham Kovoor
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- * E-mail: (AK); (JC)
| | - Jeremy Celver
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, United States of America
- * E-mail: (AK); (JC)
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Ye Y, Sun Z, Guo A, Song LS, Grobe JL, Chen S. Ablation of the GNB3 gene in mice does not affect body weight, metabolism or blood pressure, but causes bradycardia. Cell Signal 2014; 26:2514-20. [PMID: 25093805 DOI: 10.1016/j.cellsig.2014.07.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 06/26/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022]
Abstract
G protein β3 (Gβ3) is an isoform of heterotrimeric G protein β subunits involved in transducing G protein coupled receptor (GPCR) signaling. Polymorphisms in Gβ3 (GNB3) are associated with many human disorders (e.g. hypertension, diabetes and obesity) but the role of GNB3 in these pathogeneses remains unclear. Here, Gβ3-null mice (GNB3(-/-)) were characterized to determine how Gβ3 functions to regulate blood pressure, body weight and metabolism. We found Gβ3 expression restricted to limited types of tissues, including the retina, several regions of the brain and heart ventricles. Gβ3-deficient mice were normal as judged by body weight gain by age or by feeding with high-fat diet (HFD); glucose tolerance and insulin sensitivity; baseline blood pressure and angiotensin II infusion-induced hypertension. During tail-cuff blood pressure measurements, however, Gβ3-null mice had slower heart rates (~450 vs ~500 beats/min). This bradycardia was not observed in isolated and perfused Gβ3-null mouse hearts. Moreover, mouse hearts isolated from GNB3(-/-) and controls responded equivalently to muscarinic receptor- and β-adrenergic receptor-stimulated bradycardia and tachycardia, respectively. Since no difference was seen in isolated hearts, Gβ3 is unlikely to be involved directly in the GPCR signaling activity that controls heart pacemaker activity. These results demonstrate that although Gβ3 appears dispensable in mice for the regulation of blood pressure, body weight and metabolic features associated with obesity and diabetes, Gβ3 may regulate heart rate.
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Affiliation(s)
- Yuanchao Ye
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Zhizeng Sun
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Ang Guo
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Long-Sheng Song
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Justin L Grobe
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Songhai Chen
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA; Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA.
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25
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Fajardo-Serrano A, Wydeven N, Young D, Watanabe M, Shigemoto R, Martemyanov KA, Wickman K, Luján R. Association of Rgs7/Gβ5 complexes with Girk channels and GABAB receptors in hippocampal CA1 pyramidal neurons. Hippocampus 2013; 23:1231-45. [PMID: 23804514 DOI: 10.1002/hipo.22161] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2013] [Indexed: 12/15/2022]
Abstract
In the hippocampus, signaling through G protein-coupled receptors is modulated by Regulators of G protein signaling (Rgs) proteins, which act to stimulate the rate of GTP hydrolysis, and consequently, G protein inactivation. The R7-Rgs subfamily selectively deactivates the G(i/o)-class of Gα subunits that mediate the action of several GPCRs. Here, we used co-immunoprecipitation, electrophysiology and immunoelectron microscopy techniques to investigate the formation of macromolecular complexes and spatial relationship of Rgs7/Gβ5 complexes and its prototypical signaling partners, the GABAB receptor and Girk channel. Co-expression of recombinant GABAB receptors and Girk channels in combination with co-immunoprecipitation experiments established that the Rgs7/Gβ5 forms complexes with GABAB receptors or Girk channels. Using electrophysiological experiments, we found that GABAB -Girk current deactivation kinetics was markedly faster in cells coexpressing Rgs7/Gβ5. At the electron microscopic level, immunolabeling for Rgs7 and Gβ5 proteins was found primarily in the dendritic layers of the hippocampus and showed similar distribution patterns. Immunoreactivity was mostly localized along the extrasynaptic plasma membrane of dendritic shafts and spines of pyramidal cells and, to a lesser extent, to that of presynaptic terminals. Quantitative analysis of immunogold particles for Rgs7 and Gβ5 revealed an enrichment of the two proteins around excitatory synapses on dendritic spines, virtually identical to that of Girk2 and GABAB1 . These data support the existence of macromolecular complexes composed of GABAB receptor-G protein-Rgs7-Girk channels in which Rgs7 and Gβ5 proteins may preferentialy modulate GABAB receptor signaling through the deactivation of Girk channels on dendritic spines. In contrast, Rgs7 and Girk2 were associated but mainly segregated from GABAB1 in dendritic shafts, where Rgs7/Gβ5 signaling complexes might modulate Girk-dependent signaling via a different metabotropic receptor(s).
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Affiliation(s)
- Ana Fajardo-Serrano
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02006, Albacete, Spain
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26
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Leo D, Gainetdinov RR. Transgenic mouse models for ADHD. Cell Tissue Res 2013; 354:259-71. [PMID: 23681253 PMCID: PMC3785710 DOI: 10.1007/s00441-013-1639-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 04/15/2013] [Indexed: 12/20/2022]
Abstract
Attention-deficit hyperactivity disorder (ADHD) is a developmental disorder characterized by symptoms of inattention, impulsivity and hyperactivity that adversely affect many aspects of life. Whereas the etiology of ADHD remains unknown, growing evidence indicates a genetic involvement in the development of this disorder. The brain circuits associated with ADHD are rich in monoamines, which are involved in the mechanism of action of psychostimulants and other medications used to treat this disorder. Dopamine (DA) is believed to play a major role in ADHD but other neurotransmitters are certainly also involved. Genetically modified mice have become an indispensable tool used to analyze the contribution of genetic factors in the pathogenesis of human disorders. Although rodent models cannot fully recapitulate complex human psychiatric disorders such as ADHD, transgenic mice offer an opportunity to directly investigate in vivo the specific roles of novel candidate genes identified in ADHD patients. Several knock-out and transgenic mouse models have been proposed as ADHD models, mostly based on targeting genes involved in DA transmission, including the gene encoding the dopamine transporter (DAT1). These mutant models provided an opportunity to evaluate the contribution of dopamine-related processes to brain pathology, to dissect the neuronal circuitry and molecular mechanisms involved in the antihyperkinetic action of psychostimulants and to evaluate novel treatments for ADHD. New transgenic models mouse models targeting other genes have recently been proposed for ADHD. Here, we discuss the recent advances and pitfalls in modeling ADHD endophenotypes in genetically altered animals.
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Affiliation(s)
- Damiana Leo
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Via Morego 30, Genoa, Italy,
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Xie K, Masuho I, Brand C, Dessauer CW, Martemyanov KA. The complex of G protein regulator RGS9-2 and Gβ(5) controls sensitization and signaling kinetics of type 5 adenylyl cyclase in the striatum. Sci Signal 2012; 5:ra63. [PMID: 22932702 DOI: 10.1126/scisignal.2002922] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Multiple neurotransmitter systems in the striatum converge to regulate the excitability of striatal neurons by activating several heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors (GPCRs) that signal to the type 5 adenylyl cyclase (AC5), the key effector enzyme that produces the intracellular second messenger cyclic adenosine monophosphate (cAMP). Plasticity of cAMP signaling in the striatum is thought to play an essential role in the development of drug addiction. We showed that the complex of the ninth regulator of G protein signaling (RGS9-2) with the G protein β subunit (Gβ(5)) critically controlled signaling from dopamine and opioid GPCRs to AC5 in the striatum. RGS9-2/Gβ(5) directly interacted with and suppressed the basal activity of AC5. In addition, the RGS9-2/Gβ(5) complex attenuated the stimulatory action of Gβγ on AC5 by facilitating the GTPase (guanosine triphosphatase) activity of Gα(o), thus promoting the formation of the inactive heterotrimer and inhibiting Gβγ. Furthermore, by increasing the deactivation rate of Gα(i), RGS9-2/Gβ(5) facilitated the recovery of AC5 from inhibition. Mice lacking RGS9 showed increased cAMP production and, upon withdrawal from opioid administration, enhanced sensitization of AC5. Our findings establish RGS9-2/Gβ(5) complexes as regulators of three key aspects of cAMP signaling: basal activity, sensitization, and temporal kinetics of AC5, thus highlighting the role of this complex in regulating both inhibitory and stimulatory GPCRs that shape cAMP signaling in the striatum.
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Affiliation(s)
- Keqiang Xie
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
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28
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Regulators of G protein signaling RGS7 and RGS11 determine the onset of the light response in ON bipolar neurons. Proc Natl Acad Sci U S A 2012; 109:7905-10. [PMID: 22547806 DOI: 10.1073/pnas.1202332109] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The time course of signaling via heterotrimeric G proteins is controlled through their activation by G-protein coupled receptors and deactivation through the action of GTPase accelerating proteins (GAPs). Here we identify RGS7 and RGS11 as the key GAPs in the mGluR6 pathway of retinal rod ON bipolar cells that set the sensitivity and time course of light-evoked responses. We showed using electroretinography and single cell recordings that the elimination of RGS7 did not influence dark-adapted light-evoked responses, but the concurrent elimination of RGS11 severely reduced their magnitude and dramatically slowed the onset of the response. In RGS7/RGS11 double-knockout mice, light-evoked responses in rod ON bipolar cells were only observed during persistent activation of rod photoreceptors that saturate rods. These observations are consistent with persistently high G-protein activity in rod ON bipolar cell dendrites caused by the absence of the dominant GAP, biasing TRPM1 channels to the closed state.
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Maity B, Stewart A, Yang J, Loo L, Sheff D, Shepherd AJ, Mohapatra DP, Fisher RA. Regulator of G protein signaling 6 (RGS6) protein ensures coordination of motor movement by modulating GABAB receptor signaling. J Biol Chem 2011; 287:4972-81. [PMID: 22179605 DOI: 10.1074/jbc.m111.297218] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
γ-Aminobutyric acid (GABA) release from inhibitory interneurons located within the cerebellar cortex limits the extent of neuronal excitation in part through activation of metabotropic GABA(B) receptors. Stimulation of these receptors triggers a number of downstream signaling events, including activation of GIRK channels by the Gβγ dimer resulting in membrane hyperpolarization and inhibition of neurotransmitter release from presynaptic sites. Here, we identify RGS6, a member of the R7 subfamily of RGS proteins, as a key regulator of GABA(B)R signaling in cerebellum. RGS6 is enriched in the granule cell layer of the cerebellum along with neuronal GIRK channel subunits 1 and 2 where RGS6 forms a complex with known binding partners Gβ(5) and R7BP. Mice lacking RGS6 exhibit abnormal gait and ataxia characterized by impaired rotarod performance improved by treatment with a GABA(B)R antagonist. RGS6(-/-) mice administered baclofen also showed exaggerated motor coordination deficits compared with their wild-type counterparts. Isolated cerebellar neurons natively expressed RGS6, GABA(B)R, and GIRK channel subunits, and cerebellar granule neurons from RGS6(-/-) mice showed a significant delay in the deactivation kinetics of baclofen-induced GIRK channel currents. These results establish RGS6 as a key component of GABA(B)R signaling and represent the first demonstration of an essential role for modulatory actions of RGS proteins in adult cerebellum. Dysregulation of RGS6 expression in human patients could potentially contribute to loss of motor coordination and, thus, pharmacological manipulation of RGS6 levels might represent a viable means to treat patients with ataxias of cerebellar origin.
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Affiliation(s)
- Biswanath Maity
- Department of Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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