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Campos-Ríos A, Rueda-Ruzafa L, Lamas JA. The Relevance of GIRK Channels in Heart Function. MEMBRANES 2022; 12:1119. [PMID: 36363674 PMCID: PMC9698958 DOI: 10.3390/membranes12111119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/06/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Among the large number of potassium-channel families implicated in the control of neuronal excitability, G-protein-gated inwardly rectifying potassium channels (GIRK/Kir3) have been found to be a main factor in heart control. These channels are activated following the modulation of G-protein-coupled receptors and, although they have been implicated in different neurological diseases in both human and animal studies of the central nervous system, the therapeutic potential of different subtypes of these channel families in cardiac conditions has remained untapped. As they have emerged as a promising potential tool to treat a variety of conditions that disrupt neuronal homeostasis, many studies have started to focus on these channels as mediators of cardiac dynamics, thus leading to research into their implication in cardiovascular conditions. Our aim is to review the latest advances in GIRK modulation in the heart and their role in the cardiovascular system.
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Affiliation(s)
- Ana Campos-Ríos
- CINBIO, Laboratory of Neuroscience, University of Vigo, 36310 Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), 15706 Vigo, Spain
| | - Lola Rueda-Ruzafa
- Department of Nursing Science, Physiotherapy and Medicine, Faculty of Health Sciences, University of Almeria, 04120 Almeria, Spain
| | - José Antonio Lamas
- CINBIO, Laboratory of Neuroscience, University of Vigo, 36310 Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), 15706 Vigo, Spain
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2
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GIRK Channels as Candidate Targets for the Treatment of Substance Use Disorders. Biomedicines 2022; 10:biomedicines10102552. [PMID: 36289814 PMCID: PMC9599444 DOI: 10.3390/biomedicines10102552] [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: 08/31/2022] [Revised: 10/05/2022] [Accepted: 10/09/2022] [Indexed: 11/16/2022] Open
Abstract
Substance use disorders (SUDs) are chronic, lifelong disorders that have serious consequences. Repeated substance use alters brain function. G-protein-activated inwardly rectifying potassium (GIRK) channels are expressed widely in the brain, including the reward system, and regulate neuronal excitability. Functional GIRK channels are identified as heterotetramers of GIRK subunits (GIRK1–4). The GIRK1, GIRK2, and GIRK3 subunits are mainly expressed in rodent brain regions, and various addictive substances act on the brain through GIRK channels. Studies with animals (knockout and missense mutation animals) and humans have demonstrated the involvement of GIRK channels in the effects of addictive substances. Additionally, GIRK channel blockers affect behavioral responses to addictive substances. Thus, GIRK channels play a key role in SUDs, and GIRK channel modulators may be candidate medications. Ifenprodil is a GIRK channel blocker that does not have serious side effects. Two clinical trials were conducted to investigate the effects of ifenprodil in patients with alcohol or methamphetamine use disorder. Although the number of participants was relatively low, evidence of its safety and efficacy was found. The present review discusses the potential of GIRK channel modulators as possible medications for addiction. Therapeutic agents that target GIRK channels may be promising for the treatment of SUDs.
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Leung HW, Foo G, VanDongen A. Arc Regulates Transcription of Genes for Plasticity, Excitability and Alzheimer’s Disease. Biomedicines 2022; 10:biomedicines10081946. [PMID: 36009494 PMCID: PMC9405677 DOI: 10.3390/biomedicines10081946] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/21/2022] [Accepted: 07/25/2022] [Indexed: 02/06/2023] Open
Abstract
The immediate early gene Arc is a master regulator of synaptic function and a critical determinant of memory consolidation. Here, we show that Arc interacts with dynamic chromatin and closely associates with histone markers for active enhancers and transcription in cultured rat hippocampal neurons. Both these histone modifications, H3K27Ac and H3K9Ac, have recently been shown to be upregulated in late-onset Alzheimer’s disease (AD). When Arc induction by pharmacological network activation was prevented using a short hairpin RNA, the expression profile was altered for over 1900 genes, which included genes associated with synaptic function, neuronal plasticity, intrinsic excitability, and signalling pathways. Interestingly, about 100 Arc-dependent genes are associated with the pathophysiology of AD. When endogenous Arc expression was induced in HEK293T cells, the transcription of many neuronal genes was increased, suggesting that Arc can control expression in the absence of activated signalling pathways. Taken together, these data establish Arc as a master regulator of neuronal activity-dependent gene expression and suggest that it plays a significant role in the pathophysiology of AD.
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Affiliation(s)
| | - Gabriel Foo
- Duke-NUS Medical School, Singapore 169857, Singapore
| | - Antonius VanDongen
- Duke-NUS Medical School, Singapore 169857, Singapore
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710, USA
- Correspondence:
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4
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Akyuz E, Koklu B, Uner A, Angelopoulou E, Paudel YN. Envisioning the role of inwardly rectifying potassium (Kir) channel in epilepsy. J Neurosci Res 2021; 100:413-443. [PMID: 34713909 DOI: 10.1002/jnr.24985] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 09/23/2021] [Accepted: 10/01/2021] [Indexed: 01/29/2023]
Abstract
Epilepsy is a devastating neurological disorder characterized by recurrent seizures attributed to the disruption of the dynamic excitatory and inhibitory balance in the brain. Epilepsy has emerged as a global health concern affecting about 70 million people worldwide. Despite recent advances in pre-clinical and clinical research, its etiopathogenesis remains obscure, and there are still no treatment strategies modifying disease progression. Although the precise molecular mechanisms underlying epileptogenesis have not been clarified yet, the role of ion channels as regulators of cellular excitability has increasingly gained attention. In this regard, emerging evidence highlights the potential implication of inwardly rectifying potassium (Kir) channels in epileptogenesis. Kir channels consist of seven different subfamilies (Kir1-Kir7), and they are highly expressed in both neuronal and glial cells in the central nervous system. These channels control the cell volume and excitability. In this review, we discuss preclinical and clinical evidence on the role of the several subfamilies of Kir channels in epileptogenesis, aiming to shed more light on the pathogenesis of this disorder and pave the way for future novel therapeutic approaches.
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Affiliation(s)
- Enes Akyuz
- Faculty of International Medicine, Department of Biophysics, University of Health Sciences, Istanbul, Turkey
| | - Betul Koklu
- Faculty of Medicine, Namık Kemal University, Tekirdağ, Turkey
| | - Arda Uner
- Faculty of Medicine, Yozgat Bozok University, Yozgat, Turkey
| | - Efthalia Angelopoulou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Yam Nath Paudel
- Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
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Alfaro-Ruiz R, Martín-Belmonte A, Aguado C, Hernández F, Moreno-Martínez AE, Ávila J, Luján R. The Expression and Localisation of G-Protein-Coupled Inwardly Rectifying Potassium (GIRK) Channels Is Differentially Altered in the Hippocampus of Two Mouse Models of Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222011106. [PMID: 34681766 PMCID: PMC8541655 DOI: 10.3390/ijms222011106] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 12/31/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are the main targets controlling excitability and synaptic plasticity on hippocampal neurons. Consequently, dysfunction of GIRK-mediated signalling has been implicated in the pathophysiology of Alzheimer´s disease (AD). Here, we provide a quantitative description on the expression and localisation patterns of GIRK2 in two transgenic mice models of AD (P301S and APP/PS1 mice), combining histoblots and immunoelectron microscopic approaches. The histoblot technique revealed differences in the expression of GIRK2 in the two transgenic mice models. The expression of GIRK2 was significantly reduced in the hippocampus of P301S mice in a laminar-specific manner at 10 months of age but was unaltered in APP/PS1 mice at 12 months compared to age-matched wild type mice. Ultrastructural approaches using the pre-embedding immunogold technique, demonstrated that the subcellular localisation of GIRK2 was significantly reduced along the neuronal surface of CA1 pyramidal cells, but increased in its frequency at cytoplasmic sites, in both P301S and APP/PS1 mice. We also found a decrease in plasma membrane GIRK2 channels in axon terminals contacting dendritic spines of CA1 pyramidal cells in P301S and APP/PS1 mice. These data demonstrate for the first time a redistribution of GIRK channels from the plasma membrane to intracellular sites in different compartments of CA1 pyramidal cells. Altogether, the pre- and post-synaptic reduction of GIRK2 channels suggest that GIRK-mediated alteration of the excitability in pyramidal cells could contribute to the cognitive dysfunctions as described in the two AD animal models.
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Affiliation(s)
- Rocío Alfaro-Ruiz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Félix Hernández
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, ISCIII, 28049 Madrid, Spain; (F.H.); (J.Á.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, 28049 Madrid, Spain
| | - Ana Esther Moreno-Martínez
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
| | - Jesús Ávila
- Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas, ISCIII, 28049 Madrid, Spain; (F.H.); (J.Á.)
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, 28049 Madrid, Spain
| | - Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain; (R.A.-R.); (A.M.-B.); (C.A.); (A.E.M.-M.)
- Correspondence: ; Tel.: +34-967-599200 (ext. 2196)
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Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
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Identification of a G-Protein-Independent Activator of GIRK Channels. Cell Rep 2021; 31:107770. [PMID: 32553165 DOI: 10.1016/j.celrep.2020.107770] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/24/2020] [Accepted: 05/22/2020] [Indexed: 12/18/2022] Open
Abstract
G-protein-gated inwardly rectifying K+ (GIRK) channels are essential effectors of inhibitory neurotransmission in the brain. GIRK channels have been implicated in diseases with abnormal neuronal excitability, including epilepsy and addiction. GIRK channels are tetramers composed of either the same subunit (e.g., homotetramers) or different subunits (e.g., heterotetramers). Compounds that specifically target subsets of GIRK channels in vivo are lacking. Previous studies have shown that alcohol directly activates GIRK channels through a hydrophobic pocket located in the cytoplasmic domain of the channel. Here, we report the identification and functional characterization of a GIRK1-selective activator, termed GiGA1, that targets the alcohol pocket. GiGA1 activates GIRK1/GIRK2 both in vitro and in vivo and, in turn, mitigates the effects of a convulsant in an acute epilepsy mouse model. These results shed light on the structure-based development of subunit-specific GIRK modulators that could provide potential treatments for brain disorders.
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Therapeutic potential of targeting G protein-gated inwardly rectifying potassium (GIRK) channels in the central nervous system. Pharmacol Ther 2021; 223:107808. [PMID: 33476640 DOI: 10.1016/j.pharmthera.2021.107808] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 01/05/2021] [Indexed: 12/15/2022]
Abstract
G protein-gated inwardly rectifying potassium channels (Kir3/GirK) are important for maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Coupled to numerous G protein-coupled receptors (GPCRs), they mediate the effects of many neurotransmitters, neuromodulators and hormones contributing to the general homeostasis and particular synaptic plasticity processes, learning, memory and pain signaling. A growing number of behavioral and genetic studies suggest a critical role for the appropriate functioning of the central nervous system, as well as their involvement in many neurologic and psychiatric conditions, such as neurodegenerative diseases, mood disorders, attention deficit hyperactivity disorder, schizophrenia, epilepsy, alcoholism and drug addiction. Hence, GirK channels emerge as a very promising tool to be targeted in the current scenario where these conditions already are or will become a global public health problem. This review examines recent findings on the physiology, function, dysfunction, and pharmacology of GirK channels in the central nervous system and highlights the relevance of GirK channels as a worthful potential target to improve therapies for related diseases.
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9
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Ziegler GC, Röser C, Renner T, Hahn T, Ehlis AC, Weber H, Dempfle A, Walitza S, Jacob C, Romanos M, Fallgatter AJ, Reif A, Lesch KP. KCNJ6 variants modulate reward-related brain processes and impact executive functions in attention-deficit/hyperactivity disorder. Am J Med Genet B Neuropsychiatr Genet 2020; 183:247-257. [PMID: 31099984 DOI: 10.1002/ajmg.b.32734] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 04/04/2019] [Accepted: 05/06/2019] [Indexed: 12/18/2022]
Abstract
KCNJ6, encoding a potassium channel subunit, regulates the excitability of dopaminergic neurons and is expressed in attention-deficit/hyperactivity disorder (ADHD)-relevant brain regions. As a potential ADHD risk gene, KCNJ6, therefore, may contribute to the endophenotypic variation of the disorder. The impact of two SNPs, rs7275707 and rs6517442, both located in the transcriptional control region of KCNJ6, on reporter gene expression was explored in cultured cells. The KCNJ6 variants were then tested for association with ADHD and personality traits in a family-based sample (165 affected children) and an adult case-control sample (450 patients, 426 controls). Furthermore, the genotypic influence on performance in an n-back task and a cued continuous performance test (cCPT) was investigated by electroencephalography recordings. Finally, rs6517442 function was assessed by a reward anticipation paradigm using functional magnetic resonance imaging. Different haplotypes of rs7275707 and rs6517442 significantly influenced KCNJ6 gene expression proving their functional relevance on the molecular level. In the family-based children sample rs7275707 was associated with ADHD (p = .038). Moreover, rs7275707 showed association with the personality trait of Reward Dependence (p = .031). In the ADHD group, both rs7275707 and rs6517442 influenced the Go-centroid location in the cCPT and the N200 amplitude in the n-back task. Furthermore, ventral striatal activation was impacted by rs6517442 during reward anticipation. Our data indicate that functional variants of KCNJ6 influence brain activity during reward-related and executive processes supporting the view of a differential, age-dependent modulatory impact of dopamine-related brain processes in ADHD risk.
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Affiliation(s)
- Georg C Ziegler
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Christoph Röser
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Tobias Renner
- Department of Child and Adolescent Psychiatry, University of Tübingen, Tübingen, Germany
| | - Tim Hahn
- Department of Psychiatry and Psychotherapy, University of Münster, Münster, Germany
| | - Ann-Christine Ehlis
- Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| | - Heike Weber
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany
| | - Astrid Dempfle
- Institute of Medical Biometry and Statistics, Christian Albrecht-University Kiel, Kiel, Germany
| | - Susanne Walitza
- Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital, University of Zurich, Zurich, Switzerland
| | - Christian Jacob
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Psychiatry and Psychotherapy, Medius Hospital of Kirchheim, Kirchheim unter Teck, Germany
| | - Marcel Romanos
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University of Würzburg, Würzburg, Germany
| | - Andreas J Fallgatter
- Department of Psychiatry and Psychotherapy, University of Tübingen, Tübingen, Germany
| | - Andreas Reif
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Psychiatry and Psychotherapy, University of Frankfurt, Frankfurt, Germany
| | - Klaus-Peter Lesch
- Division of Molecular Psychiatry, ADHD Clinical Research Unit, Laboratory of Translational Neuroscience, Center of Mental Health, University of Würzburg, Würzburg, Germany.,Department of Translational Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands.,Laboratory of Psychiatric Neurobiology, Institute of Molecular Medicine, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
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10
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Sancho M, Welsh DG. K IR channels in the microvasculature: Regulatory properties and the lipid-hemodynamic environment. CURRENT TOPICS IN MEMBRANES 2020; 85:227-259. [PMID: 32402641 DOI: 10.1016/bs.ctm.2020.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Basal tone and perfusion control is set in cerebral arteries by the sensing of pressure and flow, key hemodynamic stimuli. These forces establish a contractile foundation within arterial networks upon which local neurovascular stimuli operate. This fundamental process is intimately tied to arterial VM and the rise in cytosolic [Ca2+] by the graded opening of voltage-operated Ca2+ channels. Arterial VM is in turn controlled by a dynamic interaction among several resident ion channels, KIR being one of particular significance. As the name suggests, KIR displays strong inward rectification, retains a small outward component, potentiated by extracellular K+ and blocked by micromolar Ba2+. Cerebrovascular KIR is unique from other K+ currents as it is present in both smooth muscle and endothelium yet lacking in classical regulatory modulation. Such observations have fostered the view that KIR is nothing more than a background conductance, activated by extracellular K+ and which passively facilitates dilation. Recent work in cell model systems has; however, identified two membrane lipids, phosphatidylinositol 4,5-bisphosphate (PIP2) and cholesterol, that interact with KIR2.x, to stabilize the channel in the preferred open or silent state, respectively. Translating this unique form of regulation, recent studies have demonstrated that specific lipid-protein interactions enable unique KIR populations to sense distinct hemodynamic stimuli and set basal tone. This review summarizes the current knowledge of vascular KIR channels and how the lipid and hemodynamic impact their activity.
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Affiliation(s)
- Maria Sancho
- Robarts Research Institute and the Department of Physiology & Pharmacology, University of Western Ontario, London, ON, Canada
| | - Donald G Welsh
- Robarts Research Institute and the Department of Physiology & Pharmacology, University of Western Ontario, London, ON, Canada.
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Dehbozorghi S, Bagheri S, Moradi K, Shokraee K, Mohammadi MR, Akhondzadeh S. Efficacy and safety of tipepidine as adjunctive therapy in children with attention-deficit/hyperactivity disorder: Randomized, double-blind, placebo-controlled clinical trial. Psychiatry Clin Neurosci 2019; 73:690-696. [PMID: 31294924 DOI: 10.1111/pcn.12913] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/12/2019] [Accepted: 07/02/2019] [Indexed: 12/31/2022]
Abstract
AIM This study evaluated the efficacy and safety of tipepidine as an add-on to methylphenidate in the drug treatment of attention-deficit/hyperactivity disorder (ADHD). METHODS This study was an 8-week, randomized, parallel group, double-blind, placebo-controlled trial recruiting 53 ADHD-diagnosed children. Patients were randomly divided to receive methylphenidate + tipepidine or methylphenidate + placebo for 8 weeks. Participants were assessed using the parent version of ADHD Rating Scale-IV and the Clinical Global Impression scale at baseline, at week 4, and at the end of the trial. Moreover, the safety and tolerability of the treatment strategies were compared. RESULTS On general linear model repeated measures analysis a significant effect was seen for time × treatment interaction on the total and hyperactivity-impulsivity subscales of the Parent ADHD Rating Scale-IV during the trial period (Greenhouse-Geisser corrected: F = 3.45, d.f. = 1.52, P = 0.049, and F = 5.17, d.f. = 1.52, P = 0.014, respectively). The effect for time × treatment interaction, however, was not significant on Clinical Global Impression-Severity scale (Greenhouse-Geisser corrected: F = 1.79, d.f. = 1.43, P = 0.182). The frequencies of adverse events were similar between the two groups. CONCLUSION Eight weeks of treatment with tipepidine, as a supplementary medication, resulted in satisfactory efficacy and safety of the adjuvant therapy in management of patients with ADHD. Rigorous investigations, however, involving larger sample sizes, more extended treatment periods, and dose responses should be considered.
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Affiliation(s)
- Sara Dehbozorghi
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Sayna Bagheri
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Kamyar Moradi
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Kamyar Shokraee
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad-Reza Mohammadi
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Shahin Akhondzadeh
- Psychiatric Research Center, Roozbeh Psychiatric Hospital, Tehran University of Medical Sciences, Tehran, Iran
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12
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Vo BN, Abney KK, Anderson A, Marron Fernandez de Velasco E, Benneyworth MA, Daniels JS, Morrison RD, Hopkins CR, Weaver CD, Wickman K. VU0810464, a non-urea G protein-gated inwardly rectifying K + (K ir 3/GIRK) channel activator, exhibits enhanced selectivity for neuronal K ir 3 channels and reduces stress-induced hyperthermia in mice. Br J Pharmacol 2019; 176:2238-2249. [PMID: 30924523 DOI: 10.1111/bph.14671] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/16/2019] [Accepted: 02/20/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE G protein-gated inwardly rectifying K+ (Kir 3) channels moderate the activity of excitable cells and have been implicated in neurological disorders and cardiac arrhythmias. Most neuronal Kir 3 channels consist of Kir 3.1 and Kir 3.2 subtypes, while cardiac Kir 3 channels consist of Kir 3.1 and Kir 3.4 subtypes. Previously, we identified a family of urea-containing Kir 3 channel activators, but these molecules exhibit suboptimal pharmacokinetic properties and modest selectivity for Kir 3.1/3.2 relative to Kir 3.1/3.4 channels. Here, we characterize a non-urea activator, VU0810464, which displays nanomolar potency as a Kir 3.1/3.2 activator, improved selectivity for neuronal Kir 3 channels, and improved brain penetration. EXPERIMENTAL APPROACH We used whole-cell electrophysiology to measure the efficacy and potency of VU0810464 in neurons and the selectivity of VU0810464 for neuronal and cardiac Kir 3 channel subtypes. We tested VU0810464 in vivo in stress-induced hyperthermia and elevated plus maze paradigms. Parallel studies with ML297, the prototypical activator of Kir 3.1-containing Kir 3 channels, were performed to permit direct comparisons. KEY RESULTS VU0810464 and ML297 exhibited comparable efficacy and potency as neuronal Kir 3 channel activators, but VU0810464 was more selective for neuronal Kir 3 channels. VU0810464, like ML297, reduced stress-induced hyperthermia in a Kir 3-dependent manner in mice. ML297, but not VU0810464, decreased anxiety-related behaviour as assessed with the elevated plus maze test. CONCLUSION AND IMPLICATIONS VU0810464 represents a new class of Kir 3 channel activator with enhanced selectivity for Kir 3.1/3.2 channels. VU0810464 may be useful for examining Kir 3.1/3.2 channel contributions to complex behaviours and for probing the potential of Kir 3 channel-dependent manipulations to treat neurological disorders.
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Affiliation(s)
- Baovi N Vo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN
| | - Kristopher K Abney
- School of Graduate Studies and Research, Meharry Medical College, Nashville, TN
| | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN
| | | | | | | | - Ryan D Morrison
- Research and Development, Precera Bioscience, Inc., Franklin, TN
| | - Corey R Hopkins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN
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Sánchez-Rodríguez I, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. Role of GirK Channels in Long-Term Potentiation of Synaptic Inhibition in an In Vivo Mouse Model of Early Amyloid- β Pathology. Int J Mol Sci 2019; 20:ijms20051168. [PMID: 30866445 PMCID: PMC6429279 DOI: 10.3390/ijms20051168] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 02/26/2019] [Accepted: 03/02/2019] [Indexed: 01/01/2023] Open
Abstract
Imbalances of excitatory/inhibitory synaptic transmission occur early in the pathogenesis of Alzheimer’s disease (AD), leading to hippocampal hyperexcitability and causing synaptic, network, and cognitive dysfunctions. G-protein-gated potassium (GirK) channels play a key role in the control of neuronal excitability, contributing to inhibitory signaling. Here, we evaluate the relationship between GirK channel activity and inhibitory hippocampal functionality in vivo. In a non-transgenic mouse model of AD, field postsynaptic potentials (fPSPs) from the CA3–CA1 synapse in the dorsal hippocampus were recorded in freely moving mice. Intracerebroventricular (ICV) injections of amyloid-β (Aβ) or GirK channel modulators impaired ionotropic (GABAA-mediated fPSPs) and metabotropic (GirK-mediated fPSPs) inhibitory signaling and disrupted the potentiation of synaptic inhibition. However, the activation of GirK channels prevented Aβ-induced changes in GABAA components. Our data shows, for the first time, the presence of long-term potentiation (LTP) for both the GABAA and GirK-mediated inhibitory postsynaptic responses in vivo. In addition, our results support the importance of an accurate level of GirK-dependent signaling for dorsal hippocampal performance in early amyloid pathology models by controlling the excess of excitation that disrupts synaptic plasticity processes.
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Affiliation(s)
- Irene Sánchez-Rodríguez
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
| | - Agnès Gruart
- Division of Neurosciences, University Pablo de Olavide, 41013 Seville, Spain.
| | | | - Lydia Jiménez-Díaz
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
| | - Juan D Navarro-López
- Neurophysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 13071 Ciudad Real, Spain.
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14
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Ahmadian-Moghadam H, Sadat-Shirazi MS, Zarrindast MR. Cocaine- and amphetamine-regulated transcript (CART): A multifaceted neuropeptide. Peptides 2018; 110:56-77. [PMID: 30391426 DOI: 10.1016/j.peptides.2018.10.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 10/15/2018] [Accepted: 10/29/2018] [Indexed: 12/12/2022]
Abstract
Over the last 35 years, the continuous discovery of novel neuropeptides has been the key to the better understanding of how the central nervous system has integrated with neuronal signals and behavioral responses. Cocaine and amphetamine-regulated transcript (CART) was discovered in 1995 in the rat striatum but later was found to be highly expressed in the hypothalamus. The widespread distribution of CART peptide in the brain complicated the understanding of the role played by this neurotransmitter. The main objective of the current compact review is to piece together the fragments of available information about origin, expression, distribution, projection, and function of CART peptides. Accumulative evidence suggests CART as a neurotransmitter and neuroprotective agent that is mainly involved in regulation of feeding, addiction, stress, anxiety, innate fear, neurological disease, neuropathic pain, depression, osteoporosis, insulin secretion, learning, memory, reproduction, vision, sleep, thirst and body temperature. In spite of the vast number of studies about the CART, the overall pictures about the CART functions are sketchy. First, there is a lack of information about cloned receptor, specific agonist and antagonist. Second, CART peptides are detected in discrete sets of neurons that can modulate countless activities and third; CART peptides exist in several fragments due to post-translational processing. For these reasons the overall picture about the CART peptides are sketchy and confounding.
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Affiliation(s)
- Hamid Ahmadian-Moghadam
- Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mohammad-Reza Zarrindast
- Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran; Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Endocrinology and Metabolism Research Institute, Tehran University of Medical Science, Tehran, Iran.
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15
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Lee SW, Anderson A, Guzman PA, Nakano A, Tolkacheva EG, Wickman K. Atrial GIRK Channels Mediate the Effects of Vagus Nerve Stimulation on Heart Rate Dynamics and Arrhythmogenesis. Front Physiol 2018; 9:943. [PMID: 30072916 PMCID: PMC6060443 DOI: 10.3389/fphys.2018.00943] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/27/2018] [Indexed: 01/09/2023] Open
Abstract
Diminished parasympathetic influence is central to the pathogenesis of cardiovascular diseases, including heart failure and hypertension. Stimulation of the vagus nerve has shown promise in treating cardiovascular disease, prompting renewed interest in understanding the signaling pathway(s) that mediate the vagal influence on cardiac physiology. Here, we evaluated the contribution of G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels to the effect of vagus nerve stimulation (VNS) on heart rate (HR), HR variability (HRV), and arrhythmogenesis in anesthetized mice. As parasympathetic fibers innervate both atria and ventricle, and GIRK channels contribute to the cholinergic impact on atrial and ventricular myocytes, we collected in vivo electrocardiogram recordings from mice lacking either atrial or ventricular GIRK channels, during VNS. VNS decreased HR and increased HRV in control mice, in a muscarinic receptor-dependent manner. This effect was preserved in mice lacking ventricular GIRK channels, but was nearly completely absent in mice lacking GIRK channels in the atria. In addition, atrial-specific ablation of GIRK channels conferred resistance to arrhythmic episodes induced by VNS. These data indicate that atrial GIRK channels are the primary mediators of the impact of VNS on HR, HRV, and arrhythmogenesis in the anesthetized mouse.
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Affiliation(s)
- Steven W. Lee
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Pilar A. Guzman
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States
| | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Elena G. Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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16
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Huang Y, Zhang Y, Kong S, Zang K, Jiang S, Wan L, Chen L, Wang G, Jiang M, Wang X, Hu J, Wang Y. GIRK1-mediated inwardly rectifying potassium current suppresses the epileptiform burst activities and the potential antiepileptic effect of ML297. Biomed Pharmacother 2018; 101:362-370. [PMID: 29499411 DOI: 10.1016/j.biopha.2018.02.114] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 12/24/2022] Open
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels are important inhibitory regulators of neuronal excitability in central nervous system, and the impairment of GIRK channel function has been reported to be associated with the susceptibility of epilepsy. However, the dynamics of GIRK channels in the pathogenesis of epilepsy are still unclear. In this study, our results showed that cyclothiazide, a potent convulsant, dose dependently increased the epileptiform bursting activities and suppressed the baclofen induced GIRK currents. In addition, TPQ, a selective GIRK antagonist, significantly decreased the total inwardly rectifying potassium (Kir) current, and increased the neuronal epileptiform activities. In contrast, ML297, a potent and selective GIRK channel agonist, reversed the cyclothiazide induced decrease of GIRK currents and the increase of neuronal excitability in cultured hippocampal neurons. Further investigation revealed that GIRK1, but not GIRK2, played a key role in suppressing epileptic activities. Finally, in pilocarpine mice seizure model, we demonstrated that ML297 significantly suppressed the seizure behavior. In summary, our current results indicate that GIRK channels, especially GIRK1-containing channels, are involved in epileptic activities and ML297 has a potential antiepileptic effect.
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Affiliation(s)
- Yian Huang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China; State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, Shanghai 200437, China
| | - Yuwen Zhang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Shuzhen Kong
- College of Environment and Resource, Chongqing Technology and Business University, Chongqing 400067, China
| | - Kai Zang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Shize Jiang
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200032, China
| | - Li Wan
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Lulan Chen
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Guoxiang Wang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Min Jiang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Xin Wang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China
| | - Jie Hu
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai 200032, China.
| | - Yun Wang
- Institutes of Brain Science and State Key Laboratory for Medical Neurobiology, Department of Neurology at Zhongshan Hospital, Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, China.
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17
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De Sanctis C, Bellenchi GC, Viggiano D. A meta-analytic approach to genes that are associated with impaired and elevated spatial memory performance. Psychiatry Res 2018; 261:508-516. [PMID: 29395873 DOI: 10.1016/j.psychres.2018.01.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 01/15/2018] [Accepted: 01/15/2018] [Indexed: 12/11/2022]
Abstract
Spatial memory deficits are a common hallmark of psychiatric conditions, possibly due to a genetic predisposition. Thus, unravelling the relationship between genes and memory might suggest novel therapeutic targets and pathogenetic pathways. Genetic deletions are known to lead to memory deficits (post-deletion "forgetfulness" genes, PDF), or, in few instances to improve spatial memory (post-deletion "hypermnesic" genes, PDH). To assess this topic, we performed a meta-analytic approach on memory behavior in knock-out mice. We screened 300 studies from PubMed and retrieved 87 genes tested for possible effects on spatial memory. This database was crossed with the Allen Brain Atlas (brain distribution) and the Enrichr (gene function) databases. The results show that PDF genes have higher expression level in several ventral brain structures, particularly the encephalic trunk and in the hypothalamus. Moreover, part of these genes are implicated in synaptic functions. Conversely, the PDH genes are associated to G-protein coupled receptors downstream signalling. Some candidate drugs were also found to interfere with some of the PDH genes, further suggesting that this approach might help in identifying drugs to improve memory performance in psychiatric conditions.
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Affiliation(s)
- Claudia De Sanctis
- IRCCS Neuromed, Pozzilli, IS 86077, Italy; Department of Medicine and Health Sciences, University of Molise, Via De Sanctis, Campobasso 86100, Italy
| | | | - Davide Viggiano
- Department of Medicine and Health Sciences, University of Molise, Via De Sanctis, Campobasso 86100, Italy.
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18
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TERUNUMA M. Diversity of structure and function of GABA B receptors: a complexity of GABA B-mediated signaling. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2018; 94:390-411. [PMID: 30541966 PMCID: PMC6374141 DOI: 10.2183/pjab.94.026] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/09/2018] [Indexed: 05/24/2023]
Abstract
γ-aminobutyric acid type B (GABAB) receptors are broadly expressed in the nervous system and play an important role in neuronal excitability. GABAB receptors are G protein-coupled receptors that mediate slow and prolonged inhibitory action, via activation of Gαi/o-type proteins. GABAB receptors mediate their inhibitory action through activating inwardly rectifying K+ channels, inactivating voltage-gated Ca2+ channels, and inhibiting adenylate cyclase. Functional GABAB receptors are obligate heterodimers formed by the co-assembly of R1 and R2 subunits. It is well established that GABAB receptors interact not only with G proteins and effectors but also with various proteins. This review summarizes the structure, subunit isoforms, and function of GABAB receptors, and discusses the complexity of GABAB receptors, including how receptors are localized in specific subcellular compartments, the mechanism regulating cell surface expression and mobility of the receptors, and the diversity of receptor signaling through receptor crosstalk and interacting proteins.
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Affiliation(s)
- Miho TERUNUMA
- Division of Oral Biochemistry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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19
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Lacin E, Aryal P, Glaaser IW, Bodhinathan K, Tsai E, Marsh N, Tucker SJ, Sansom MSP, Slesinger PA. Dynamic role of the tether helix in PIP 2-dependent gating of a G protein-gated potassium channel. J Gen Physiol 2017; 149:799-811. [PMID: 28720589 PMCID: PMC5560777 DOI: 10.1085/jgp.201711801] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 06/06/2017] [Accepted: 06/21/2017] [Indexed: 01/21/2023] Open
Abstract
G protein–gated inwardly rectifying potassium (GIRK) channels are activated by the phospholipid phosphatidylinositol 4,5 bisphosphate (PIP2). Using functional and computational experiments, Lacin et al. reveal that PIP2 interacts with the tether helix of the neuronal GIRK channel in a dynamic way. G protein–gated inwardly rectifying potassium (GIRK) channels control neuronal excitability in the brain and are implicated in several different neurological diseases. The anionic phospholipid phosphatidylinositol 4,5 bisphosphate (PIP2) is an essential cofactor for GIRK channel gating, but the precise mechanism by which PIP2 opens GIRK channels remains poorly understood. Previous structural studies have revealed several highly conserved, positively charged residues in the “tether helix” (C-linker) that interact with the negatively charged PIP2. However, these crystal structures of neuronal GIRK channels in complex with PIP2 provide only snapshots of PIP2’s interaction with the channel and thus lack details about the gating transitions triggered by PIP2 binding. Here, our functional studies reveal that one of these conserved basic residues in GIRK2, Lys200 (6′K), supports a complex and dynamic interaction with PIP2. When Lys200 is mutated to an uncharged amino acid, it activates the channel by enhancing the interaction with PIP2. Atomistic molecular dynamic simulations of neuronal GIRK2 with the same 6′ substitution reveal an open GIRK2 channel with PIP2 molecules adopting novel positions. This dynamic interaction with PIP2 may explain the intrinsic low open probability of GIRK channels and the mechanism underlying activation by G protein Gβγ subunits and ethanol.
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Affiliation(s)
- Emre Lacin
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Prafulla Aryal
- Department of Biochemistry, University of Oxford, Oxford, England, UK.,OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, England, UK
| | - Ian W Glaaser
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY
| | | | - Eric Tsai
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Nidaa Marsh
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Stephen J Tucker
- OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, England, UK.,Department of Physics, University of Oxford, Oxford, England, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, England, UK.,OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, England, UK
| | - Paul A Slesinger
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY .,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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20
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Marron Fernandez de Velasco E, Zhang L, N Vo B, Tipps M, Farris S, Xia Z, Anderson A, Carlblom N, Weaver CD, Dudek SM, Wickman K. GIRK2 splice variants and neuronal G protein-gated K + channels: implications for channel function and behavior. Sci Rep 2017; 7:1639. [PMID: 28487514 PMCID: PMC5431628 DOI: 10.1038/s41598-017-01820-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/03/2017] [Indexed: 11/21/2022] Open
Abstract
Many neurotransmitters directly inhibit neurons by activating G protein-gated inwardly rectifying K+ (GIRK) channels, thereby moderating the influence of excitatory input on neuronal excitability. While most neuronal GIRK channels are formed by GIRK1 and GIRK2 subunits, distinct GIRK2 isoforms generated by alternative splicing have been identified. Here, we compared the trafficking and function of two isoforms (GIRK2a and GIRK2c) expressed individually in hippocampal pyramidal neurons lacking GIRK2. GIRK2a and GIRK2c supported comparable somato-dendritic GIRK currents in Girk2−/− pyramidal neurons, although GIRK2c achieved a more uniform subcellular distribution in pyramidal neurons and supported inhibitory postsynaptic currents in distal dendrites better than GIRK2a. While over-expression of either isoform in dorsal CA1 pyramidal neurons restored contextual fear learning in a conditional Girk2−/− mouse line, GIRK2a also enhanced cue fear learning. Collectively, these data indicate that GIRK2 isoform balance within a neuron can impact the processing of afferent inhibitory input and associated behavior.
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Affiliation(s)
| | - Lei Zhang
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Baovi N Vo
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Megan Tipps
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Shannon Farris
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Zhilian Xia
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Allison Anderson
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - Nicholas Carlblom
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA
| | - C David Weaver
- Vanderbilt University, Department of Pharmacology, Nashville, TN, 37235, USA
| | - Serena M Dudek
- National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, USA
| | - Kevin Wickman
- University of Minnesota, Department of Pharmacology, Minneapolis, MN, 55455, USA.
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21
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Inhibition of 17-beta-estradiol on neuronal excitability via enhancing GIRK1-mediated inwardly rectifying potassium currents and GIRK1 expression. J Neurol Sci 2017; 375:335-341. [DOI: 10.1016/j.jns.2017.02.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Revised: 01/24/2017] [Accepted: 02/14/2017] [Indexed: 12/21/2022]
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22
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Bukiya AN, Durdagi S, Noskov S, Rosenhouse-Dantsker A. Cholesterol up-regulates neuronal G protein-gated inwardly rectifying potassium (GIRK) channel activity in the hippocampus. J Biol Chem 2017; 292:6135-6147. [PMID: 28213520 DOI: 10.1074/jbc.m116.753350] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 02/13/2017] [Indexed: 02/06/2023] Open
Abstract
Hypercholesterolemia is a well known risk factor for the development of neurodegenerative disease. However, the underlying mechanisms are mostly unknown. In recent years, it has become increasingly evident that cholesterol-driven effects on physiology and pathophysiology derive from its ability to alter the function of a variety of membrane proteins including ion channels. Yet, the effect of cholesterol on G protein-gated inwardly rectifying potassium (GIRK) channels expressed in the brain is unknown. GIRK channels mediate the actions of inhibitory brain neurotransmitters. As a result, loss of GIRK function can enhance neuron excitability, whereas gain of GIRK function can reduce neuronal activity. Here we show that in rats on a high-cholesterol diet, cholesterol levels in hippocampal neurons are increased. We also demonstrate that cholesterol plays a critical role in modulating neuronal GIRK currents. Specifically, cholesterol enrichment of rat hippocampal neurons resulted in enhanced channel activity. In accordance, elevated currents upon cholesterol enrichment were also observed in Xenopus oocytes expressing GIRK2 channels, the primary GIRK subunit expressed in the brain. Furthermore, using planar lipid bilayers, we show that although cholesterol did not affect the unitary conductance of GIRK2, it significantly enhanced the frequency of channel openings. Last, combining computational and functional approaches, we identified two putative cholesterol-binding sites in the transmembrane domain of GIRK2. These findings establish that cholesterol plays a critical role in modulating GIRK activity in the brain. Because up-regulation of GIRK function can reduce neuronal activity, our findings may lead to novel approaches for prevention and therapy of cholesterol-driven neurodegenerative disease.
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Affiliation(s)
- Anna N Bukiya
- the Department of Pharmacology, The University of Tennessee Health Science Center, Memphis, Tennessee 38103
| | - Serdar Durdagi
- the Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4 Canada, and.,the Department of Biophysics, School of Medicine, Bahcesehir University, Istanbul 34353, Turkey
| | - Sergei Noskov
- the Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4 Canada, and
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23
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Generation and vulnerability of deep cerebellar nuclei neurons in the weaver condition along the anteroposterior and mediolateral axes. Int J Dev Neurosci 2016; 49:37-45. [PMID: 26748014 DOI: 10.1016/j.ijdevneu.2015.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 12/28/2015] [Accepted: 12/28/2015] [Indexed: 02/02/2023] Open
Abstract
Production and death of deep cerebellar nuclei (DCN) neurons were investigated in the weaver condition at appropriate anatomical levels throughout the mediolateral (medial, intermediate and lateral) and rostrocaudal (rostral, middle and caudal) axes of three DCN-cell groups: the fastigial, the interposed and the dentate nuclei. Current results have denoted that the deficit of DCN neurons is always more important in the homozygous weaver than in the heterozygous weaver mice. No loss of neurons was found in the dentate nucleus. In the mediolateral axis, an intranuclear gradient of depletion was observed in the mutant mice; in a given deep nucleus, neurodegeneration was more prominent in the medial pars than in lateral ones. In the rostrocaudal axis, on the other hand, when each deep nucleus was studied and compared as a whole, neuron loss was higher in the fastigial nucleus than in the interposed nucleus, which, in turn, was more important than in the dentate nucleus. These data suggest that, in the weaver condition, an internuclear gradient of neurodegeneration exists. Moreover, neurons located in rostral parts of a given nucleus appear to be more vulnerable than those settled in middle parts and these, in turn, are more than the caudal ones. These results seem to indicate the presence of an intranuclear gradient of depletion. Current autoradiographic results have revealed that, in the rostrocaudal axis, deep neurons are settled in the weaver cerebellum following three neurogenetic gradients. The first of these is internuclear; if each deep nucleus is analyzed and compared as a whole, the fastigial nucleus has more late-generated neurons than the interposed nucleus, and this, in turn, has more than the dentate nucleus. The second gradient is also internuclear; if the proportion of late-born neurons is compared throughout the rostral levels from each deep nucleus, it is observed that proportions increase from the fastigial to the dentate nucleus. A similar picture emerges when the middle and caudal regions are taken into account. The third gradient is intranuclear; in a given deep nucleus, the rostral region always presents more late-produced neurons than the middle region and these, in turn, more than in the caudal level.
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Abstract
The approximately 350 ion channels encoded by the mammalian genome are a main pillar of the nervous system. We have determined the expression pattern of 320 channels in the two-week-old (P14) rat brain by means of non-radioactive robotic in situ hybridization. Optimized methods were developed and implemented to generate stringently coronal brain sections. The use of standardized methods permits a direct comparison of expression patterns across the entire ion channel expression pattern data set and facilitates recognizing ion channel co-expression. All expression data are made publically available at the Genepaint.org database. Inwardly rectifying potassium channels (Kir, encoded by the Kcnj genes) regulate a broad spectrum of physiological processes. Kcnj channel expression patterns generated in the present study were fitted with a deformable subdivision mesh atlas produced for the P14 rat brain. This co-registration, when combined with numerical quantification of expression strengths, allowed for semi-quantitative automated annotation of expression patterns as well as comparisons among and between Kcnj subfamilies. The expression patterns of Kcnj channel were also cross validated against previously published expression patterns of Kcnj channel genes.
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25
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Mayordomo-Cava J, Yajeya J, Navarro-López JD, Jiménez-Díaz L. Amyloid-β(25-35) Modulates the Expression of GirK and KCNQ Channel Genes in the Hippocampus. PLoS One 2015. [PMID: 26218288 PMCID: PMC4517786 DOI: 10.1371/journal.pone.0134385] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During early stages of Alzheimer's disease (AD), synaptic dysfunction induced by toxic amyloid-β (Aβ) is present before the accumulation of histopathological hallmarks of the disease. This scenario produces impaired functioning of neuronal networks, altered patterns of synchronous activity and severe functional deficits mainly due to hyperexcitability of hippocampal networks. The molecular mechanisms underlying these alterations remain unclear but functional evidence, shown by our laboratory and others, points to the involvement of receptors/channels which modulate neuronal excitability, playing a pivotal role in early Aβ-induced AD pathogenesis. In particular, two potassium channels that control neuronal excitability, G protein-coupled activated inwardly-rectifying potassium channel (GirK), and voltage-gated K channel (KCNQ), have been recently linked to Aβ pathophysiology in the hippocampus. Specifically, by using Aβ25-35, we previously found that GirK conductance is greatly decreased in the hippocampus, and similar effects have also been reported on KCNQ conductance. Thus, in the present study, our goal was to determine the effect of Aβ on the transcriptional expression pattern of 17 genes encoding neurotransmitter receptors and associated channels which maintain excitatory-inhibitory neurotransmission balance in hippocampal circuits, with special focus in potassium channels. For this purpose, we designed a systematic and reliable procedure to analyze mRNA expression by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) in hippocampal rat slices incubated with Aβ25-35. We found that: 1) Aβ down-regulated mRNA expression of ionotropic GluN1 and metabotropic mGlu1 glutamate receptor subunits as previously reported in other AD models; 2) Aβ also reduced gene expression levels of GirK2, 3, and 4 subunits, and KCNQ2 and 3 subunits, but did not change expression levels of its associated GABAB and M1 receptors, respectively. Our results provide evidence that Aβ can modulate the expression of these channels which could affect the hippocampal activity balance underlying learning and memory processes impaired in AD.
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Affiliation(s)
- Jennifer Mayordomo-Cava
- University of Castilla-La Mancha, Neurophysiology & Behavior Lab, CRIB, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Javier Yajeya
- University of Salamanca, Department of Physiology & Pharmacology, Salamanca, Spain
| | - Juan D. Navarro-López
- University of Castilla-La Mancha, Neurophysiology & Behavior Lab, CRIB, School of Medicine of Ciudad Real, Ciudad Real, Spain
- * E-mail: (LJD); (JDNL)
| | - Lydia Jiménez-Díaz
- University of Castilla-La Mancha, Neurophysiology & Behavior Lab, CRIB, School of Medicine of Ciudad Real, Ciudad Real, Spain
- * E-mail: (LJD); (JDNL)
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Lyu C, Mulder J, Barde S, Sahlholm K, Zeberg H, Nilsson J, Århem P, Hökfelt T, Fried K, Shi TJS. G protein-gated inwardly rectifying potassium channel subunits 1 and 2 are down-regulated in rat dorsal root ganglion neurons and spinal cord after peripheral axotomy. Mol Pain 2015. [PMID: 26199148 PMCID: PMC4511542 DOI: 10.1186/s12990-015-0044-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Background Increased nociceptive neuronal excitability underlies chronic pain conditions. Various ion channels, including sodium, calcium and potassium channels have pivotal roles in the control of neuronal excitability. The members of the family of G protein-gated inwardly rectifying potassium (GIRK) channels, GIRK1–4, have been implicated in modulating excitability. Here, we investigated the expression and distribution of GIRK1 and GIRK2 in normal and injured dorsal root ganglia (DRGs) and spinal cord of rats. Results We found that ~70% of the DRG neurons expressed GIRK1, while only <10% expressed GIRK2. The neurochemical profiles of GIRK1- and GIRK2-immunoreactive neurons were characterized using the neuronal markers calcitonin gene-related peptide, isolectin-B4 and neurofilament-200, and the calcium-binding proteins calbindin D28k, calretinin, parvalbumin and secretagogin. Both GIRK subunits were expressed in DRG neurons with nociceptive characteristics. However, while GIRK1 was widely expressed in several sensory neuronal subtypes, GIRK2 was detected mainly in a group of small C-fiber neurons. In the spinal dorsal horn, GIRK1- and -2-positive cell bodies and processes were mainly observed in lamina II, but also in superficial and deeper layers. Abundant GIRK1-, but not GIRK2-like immunoreactivity, was found in the ventral horn (laminae VI–X). Fourteen days after axotomy, GIRK1 and GIRK2 were down-regulated in DRG neurons at the mRNA and protein levels. Both after axotomy and rhizotomy there was a reduction of GIRK1- and -2-positive processes in the dorsal horn, suggesting a presynaptic localization of these potassium channels. Furthermore, nerve ligation caused accumulation of both subunits on both sides of the lesion, providing evidence for anterograde and retrograde fast axonal transport. Conclusions Our data support the hypothesis that reduced GIRK function is associated with increased neuronal excitability and causes sensory disturbances in post-injury conditions, including neuropathic pain. Electronic supplementary material The online version of this article (doi:10.1186/s12990-015-0044-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chuang Lyu
- School of Life Science and Technology, Harbin Institute of Technology, 150001, Harbin, China. .,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Jan Mulder
- Department of Neuroscience, Science for Life Laboratory, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Swapnali Barde
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Kristoffer Sahlholm
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Hugo Zeberg
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Johanna Nilsson
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Peter Århem
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Tomas Hökfelt
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Kaj Fried
- Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
| | - Tie-Jun Sten Shi
- School of Life Science and Technology, Harbin Institute of Technology, 150001, Harbin, China. .,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
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27
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Mayfield J, Blednov YA, Harris RA. Behavioral and Genetic Evidence for GIRK Channels in the CNS: Role in Physiology, Pathophysiology, and Drug Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:279-313. [PMID: 26422988 DOI: 10.1016/bs.irn.2015.05.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
G protein-coupled inwardly rectifying potassium (GIRK) channels are widely expressed throughout the brain and mediate the inhibitory effects of many neurotransmitters. As a result, these channels are important for normal CNS function and have also been implicated in Down syndrome, Parkinson's disease, psychiatric disorders, epilepsy, and drug addiction. Knockout mouse models have provided extensive insight into the significance of GIRK channels under these conditions. This review examines the behavioral and genetic evidence from animal models and genetic association studies in humans linking GIRK channels with CNS disorders. We further explore the possibility that subunit-selective modulators and other advanced research tools will be instrumental in establishing the role of individual GIRK subunits in drug addiction and other relevant CNS diseases and in potentially advancing treatment options for these disorders.
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Affiliation(s)
- Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA.
| | - Yuri A Blednov
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, Texas, USA
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Logothetis DE, Mahajan R, Adney SK, Ha J, Kawano T, Meng XY, Cui M. Unifying Mechanism of Controlling Kir3 Channel Activity by G Proteins and Phosphoinositides. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:1-26. [PMID: 26422981 DOI: 10.1016/bs.irn.2015.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The question that started with the pioneering work of Otto Loewi in the 1920s, to identify how stimulation of the vagus nerve decreased heart rate, is approaching its 100th year anniversary. In the meantime, we have learned that the neurotransmitter acetylcholine acting through muscarinic M2 receptors activates cardiac potassium (Kir3) channels via the βγ subunits of G proteins, an important effect that contributes to slowing atrial pacemaker activity. Concurrent stimulation of M1 or M3 receptors hydrolyzes PIP2, a signaling phospholipid essential to maintaining Kir3 channel activity, thus causing desensitization of channel activity and protecting the heart from overinhibition of pacemaker activity. Four mammalian members of the Kir3 subfamily, expressed in heart, brain, endocrine organs, etc., are modulated by a plethora of stimuli to regulate cellular excitability. With the recent great advances in ion channel structural biology, three-dimensional structures of Kir3 channels with PIP2 and the Gβγ subunits are now available. Mechanistic insights have emerged that explain how modulatory control of activity feeds into a core mechanism of channel-PIP2 interactions to regulate the conformation of channel gates. This complex but beautiful system continues to surprise us for almost 100 years with an apparent wisdom in its intricate design.
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Affiliation(s)
- Diomedes E Logothetis
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA.
| | - Rahul Mahajan
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Scott K Adney
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Junghoon Ha
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Takeharu Kawano
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Xuan-Yu Meng
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Meng Cui
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA
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Monticone S, Else T, Mulatero P, Williams TA, Rainey WE. Understanding primary aldosteronism: impact of next generation sequencing and expression profiling. Mol Cell Endocrinol 2015; 399:311-20. [PMID: 25240470 PMCID: PMC4285708 DOI: 10.1016/j.mce.2014.09.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/11/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
Abstract
Primary aldosteronism (PA) encompasses a broad, heterogeneous group of disorders including both sporadic and familial forms (familial hyperaldosteronism type I, II and III). PA is the most common form of secondary hypertension and associated with a higher rate of cardiovascular complications, compared with essential hypertension. Despite significant progress in the diagnosis and management of PA, until recently the molecular mechanisms leading to inappropriate aldosterone production were largely unknown. The introduction of next-generation sequencing has had a profound impact on the field of human genetics and has given new insight in the molecular determinants that lead to both sporadic and familial forms of PA. Here we review the recent progress toward understanding of the genetic and molecular mechanisms leading to autonomous aldosterone production in PA.
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Affiliation(s)
- Silvia Monticone
- Department of Medical Sciences, Division of Internal Medicine and Hypertension, University of Torino, Torino, Italy.
| | - Tobias Else
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Paolo Mulatero
- Department of Medical Sciences, Division of Internal Medicine and Hypertension, University of Torino, Torino, Italy
| | - Tracy A Williams
- Department of Medical Sciences, Division of Internal Medicine and Hypertension, University of Torino, Torino, Italy
| | - William E Rainey
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
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30
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Luján R, Aguado C. Localization and Targeting of GIRK Channels in Mammalian Central Neurons. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:161-200. [PMID: 26422985 DOI: 10.1016/bs.irn.2015.05.009] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
G protein-gated inwardly rectifying K(+) (GIRK/K(ir)3) channels are critical to brain function. They hyperpolarize neurons in response to activation of different G protein-coupled receptors, reducing cell excitability. Molecular cloning has revealed four distinct mammalian genes (GIRK1-4), which, with the exception of GIRK4, are broadly expressed in the central nervous system (CNS) and have been implicated in a variety of neurological disorders. Although the molecular structure and composition of GIRK channels are key determinants of their biophysical properties, their cellular and subcellular localization patterns and densities on the neuronal surface are just as important to nerve function. Current data obtained with high-resolution quantitative localization techniques reveal complex, subcellular compartment-specific distribution patterns of GIRK channel subunits. Recent efforts have focused on determining the associated proteins that form macromolecular complexes with GIRK channels. Demonstration of the precise subcellular compartmentalization of GIRK channels and their associated proteins represents a crucial step in understanding the contribution of these channels to specific aspects of neuronal function under both physiological and pathological conditions. Here, we present an overview of studies aimed at determining the cellular and subcellular localization of GIRK channel subunits in mammalian brain neurons and discuss implications for neuronal physiology.
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Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain.
| | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain
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31
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GIRK Channels: A Potential Link Between Learning and Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:239-77. [PMID: 26422987 DOI: 10.1016/bs.irn.2015.05.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The ability of drug-associated cues to reinitiate drug craving and seeking, even after long periods of abstinence, has led to the hypothesis that addiction represents a form of pathological learning, in which drugs of abuse hijack normal learning and memory processes to support long-term addictive behaviors. In this chapter, we review evidence suggesting that G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels are one mechanism through which numerous drugs of abuse can modulate learning and memory processes. We will examine the role of GIRK channels in two forms of experience-dependent long-term changes in neuronal function: homeostatic plasticity and synaptic plasticity. We will also discuss how drug-induced changes in GIRK-mediated signaling can lead to changes that support the development and maintenance of addiction.
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32
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Nagi K, Pineyro G. Kir3 channel signaling complexes: focus on opioid receptor signaling. Front Cell Neurosci 2014; 8:186. [PMID: 25071446 PMCID: PMC4085882 DOI: 10.3389/fncel.2014.00186] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 06/18/2014] [Indexed: 12/03/2022] Open
Abstract
Opioids are among the most effective drugs to treat severe pain. They produce their analgesic actions by specifically activating opioid receptors located along the pain perception pathway where they inhibit the flow of nociceptive information. This inhibition is partly accomplished by activation of hyperpolarizing G protein-coupled inwardly-rectifying potassium (GIRK or Kir3) channels. Kir3 channels control cellular excitability in the central nervous system and in the heart and, because of their ubiquitous distribution, they mediate the effects of a large range of hormones and neurotransmitters which, upon activation of corresponding G protein-coupled receptors (GPCRs) lead to channel opening. Here we analyze GPCR signaling via these effectors in reference to precoupling and collision models. Existing knowledge on signaling bias is discussed in relation to these models as a means of developing strategies to produce novel opioid analgesics with an improved side effects profile.
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Affiliation(s)
- Karim Nagi
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada
| | - Graciela Pineyro
- Département de Pharmacologie, Faculté de Médecine, Université de Montréal Montreal, QC, Canada ; Centre de Recherche du CHU Sainte-Justine Montréal, QC, Canada ; Département de Psychiatrie, Faculté de Médecine, Université de Montréal Montréal, QC, Canada
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33
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Nava-Mesa MO, Jiménez-Díaz L, Yajeya J, Navarro-Lopez JD. GABAergic neurotransmission and new strategies of neuromodulation to compensate synaptic dysfunction in early stages of Alzheimer's disease. Front Cell Neurosci 2014; 8:167. [PMID: 24987334 PMCID: PMC4070063 DOI: 10.3389/fncel.2014.00167] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/02/2014] [Indexed: 01/06/2023] Open
Abstract
Alzheimer’s disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline, brain atrophy due to neuronal and synapse loss, and formation of two pathological lesions: extracellular amyloid plaques, composed largely of amyloid-beta peptide (Aβ), and neurofibrillary tangles formed by intracellular aggregates of hyperphosphorylated tau protein. Lesions mainly accumulate in brain regions that modulate cognitive functions such as the hippocampus, septum or amygdala. These brain structures have dense reciprocal glutamatergic, cholinergic, and GABAergic connections and their relationships directly affect learning and memory processes, so they have been proposed as highly susceptible regions to suffer damage by Aβ during AD course. Last findings support the emerging concept that soluble Aβ peptides, inducing an initial stage of synaptic dysfunction which probably starts 20–30 years before the clinical onset of AD, can perturb the excitatory–inhibitory balance of neural circuitries. In turn, neurotransmission imbalance will result in altered network activity that might be responsible of cognitive deficits in AD. Therefore, Aβ interactions on neurotransmission systems in memory-related brain regions such as amygdaloid complex, medial septum or hippocampus are critical in cognitive functions and appear as a pivotal target for drug design to improve learning and dysfunctions that manifest with age. Since treatments based on glutamatergic and cholinergic pharmacology in AD have shown limited success, therapies combining modulators of different neurotransmission systems including recent findings regarding the GABAergic system, emerge as a more useful tool for the treatment, and overall prevention, of this dementia. In this review, focused on inhibitory systems, we will analyze pharmacological strategies to compensate neurotransmission imbalance that might be considered as potential therapeutic interventions in AD.
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Affiliation(s)
| | - Lydia Jiménez-Díaz
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
| | - Javier Yajeya
- Department of Physiology and Pharmacology, University of Salamanca Salamanca, Spain
| | - Juan D Navarro-Lopez
- Neurophysiology and Behavior Lab, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha Ciudad Real, Spain
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Nishizawa D, Fukuda KI, Kasai S, Ogai Y, Hasegawa J, Sato N, Yamada H, Tanioka F, Sugimura H, Hayashida M, Ikeda K. Association Between KCNJ6 (GIRK2) Gene Polymorphism rs2835859 and Post-operative Analgesia, Pain Sensitivity, and Nicotine Dependence. J Pharmacol Sci 2014; 126:253-63. [DOI: 10.1254/jphs.14189fp] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Luján R, Marron Fernandez de Velasco E, Aguado C, Wickman K. New insights into the therapeutic potential of Girk channels. Trends Neurosci 2013; 37:20-9. [PMID: 24268819 DOI: 10.1016/j.tins.2013.10.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/01/2023]
Abstract
G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.
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Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | | | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, 321 Church Street South East, Minneapolis, MN 55455, USA.
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Mesirca P, Marger L, Toyoda F, Rizzetto R, Audoubert M, Dubel S, Torrente AG, Difrancesco ML, Muller JC, Leoni AL, Couette B, Nargeot J, Clapham DE, Wickman K, Mangoni ME. The G-protein-gated K+ channel, IKACh, is required for regulation of pacemaker activity and recovery of resting heart rate after sympathetic stimulation. ACTA ACUST UNITED AC 2013; 142:113-26. [PMID: 23858001 PMCID: PMC3727310 DOI: 10.1085/jgp.201310996] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Parasympathetic regulation of sinoatrial node (SAN) pacemaker activity modulates multiple ion channels to temper heart rate. The functional role of the G-protein–activated K+ current (IKACh) in the control of SAN pacemaking and heart rate is not completely understood. We have investigated the functional consequences of loss of IKACh in cholinergic regulation of pacemaker activity of SAN cells and in heart rate control under physiological situations mimicking the fight or flight response. We used knockout mice with loss of function of the Girk4 (Kir3.4) gene (Girk4−/− mice), which codes for an integral subunit of the cardiac IKACh channel. SAN pacemaker cells from Girk4−/− mice completely lacked IKACh. Loss of IKACh strongly reduced cholinergic regulation of pacemaker activity of SAN cells and isolated intact hearts. Telemetric recordings of electrocardiograms of freely moving mice showed that heart rate measured over a 24-h recording period was moderately increased (10%) in Girk4−/− animals. Although the relative extent of heart rate regulation of Girk4−/− mice was similar to that of wild-type animals, recovery of resting heart rate after stress, physical exercise, or pharmacological β-adrenergic stimulation of SAN pacemaking was significantly delayed in Girk4−/− animals. We conclude that IKACh plays a critical role in the kinetics of heart rate recovery to resting levels after sympathetic stimulation or after direct β-adrenergic stimulation of pacemaker activity. Our study thus uncovers a novel role for IKACh in SAN physiology and heart rate regulation.
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Affiliation(s)
- Pietro Mesirca
- Centre National de la Recherche Scientifique UMR 5203, Institut de Génomique Fonctionnelle, Département de Physiologie, Laboratoire d'Excellence Canaux Ioniques d'Intérêt Thérapeutique, 34094 Montpellier, France
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Molecular basis of the facilitation of the heterooligomeric GIRK1/GIRK4 complex by cAMP dependent protein kinase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1214-21. [PMID: 23305758 PMCID: PMC3787752 DOI: 10.1016/j.bbamem.2012.12.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/04/2012] [Accepted: 12/26/2012] [Indexed: 01/01/2023]
Abstract
G-protein activated inwardly rectifying K+ channels (GIRKs) of the heterotetrameric GIRK1/GIRK4 composition mediate IK + ACh in atrium and are regulated by cAMP dependent protein kinase (PKA). Phosphorylation of GIRK1/GIRK4 complexes promotes the activation of the channel by the G-protein Gβγ-dimer (“heterologous facilitation”). Previously we reported that 3 serines/threonines (S/Ts) within the GIRK1 subunit are phosphorylated by the catalytic subunit of PKA (PKA-cs) in-vitro and are responsible for the acute functional effects exerted by PKA on the homooligomeric GIRK1F137S (GIRK1⁎) channel. Here we report that homooligomeric GIRK4WT and GIRK4S143T (GIRK4⁎) channels are clearly regulated by PKA phosphorylation. Heterooligomeric channels of the GIRK1S385CS401CT407C/GIRK4WT composition, where the GIRK1 subunit is devoid of PKA mediated phosphorylation, exhibited reduced but still significant acute effects (reduction during agonist application was ≈ 49% compared to GIRK1WT/GIRK4WT). Site directed mutagenesis of truncated cytosolic regions of GIRK4 revealed four serines/threonines (S/Ts) that were heavily phosphorylated by PKA-cs in vitro. Two of them were found to be responsible for the acute effects exerted by PKA in vivo, since the effect of cAMP injection was reduced by ≈ 99% in homooligomeric GIRK4⁎T199CS412C channels. Coexpression of GIRK1WT/GIRK4T199CS412C reduced the acute effect by ≈ 65%. Only channels of the GIRK1S385CS401CT407C/GIRK4T199CS412C composition were practically devoid of PKA mediated effects (reduction by ≈ 97%), indicating that both subunits contribute to the heterologous facilitation of IK + ACh.
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Sugaya N, Kobayashi T, Ikeda K. Role of GIRK Channels in Addictive Substance Effects. ACTA ACUST UNITED AC 2013. [DOI: 10.4303/jdar/235823] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Aguado C, Fernández-Alacid L, Cabañero MJ, Yanagawa Y, Schilling K, Watanabe M, Fritschy JM, Luján R. Differential maturation of GIRK2-expressing neurons in the mouse cerebellum. J Chem Neuroanat 2013; 47:79-89. [DOI: 10.1016/j.jchemneu.2012.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 11/22/2012] [Accepted: 11/26/2012] [Indexed: 12/22/2022]
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Kang SJ, Rangaswamy M, Manz N, Wang JC, Wetherill L, Hinrichs T, Almasy L, Brooks A, Chorlian DB, Dick D, Hesselbrock V, Kramer J, Kuperman S, Nurnberger J, Rice J, Schuckit M, Tischfield J, Bierut LJ, Edenberg HJ, Goate A, Foroud T, Porjesz B. Family-based genome-wide association study of frontal θ oscillations identifies potassium channel gene KCNJ6. GENES, BRAIN, AND BEHAVIOR 2012; 11:712-9. [PMID: 22554406 PMCID: PMC3666338 DOI: 10.1111/j.1601-183x.2012.00803.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Event-related oscillations (EROs) represent highly heritable neuroelectric correlates of cognitive processes that manifest deficits in alcoholics and in offspring at high risk to develop alcoholism. Theta ERO to targets in the visual oddball task has been shown to be an endophenotype for alcoholism. A family-based genome-wide association study was performed for the frontal theta ERO phenotype using 634 583 autosomal single nucleotide polymorphisms (SNPs) genotyped in 1560 family members from 117 families densely affected by alcohol use disorders, recruited in the Collaborative Study on the Genetics of Alcoholism. Genome-wide significant association was found with several SNPs on chromosome 21 in KCNJ6 (a potassium inward rectifier channel; KIR3.2/GIRK2), with the most significant SNP at P = 4.7 × 10(-10)). The same SNPs were also associated with EROs from central and parietal electrodes, but with less significance, suggesting that the association is frontally focused. One imputed synonymous SNP in exon four, highly correlated with our top three SNPs, was significantly associated with the frontal theta ERO phenotype. These results suggest KCNJ6 or its product GIRK2 account for some of the variations in frontal theta band oscillations. GIRK2 receptor activation contributes to slow inhibitory postsynaptic potentials that modulate neuronal excitability, and therefore influence neuronal networks.
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Affiliation(s)
- Sun J. Kang
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry and Behavioral Sciences, SUNY Downstate Medical Center, Brooklyn, NY
| | - Madhavi Rangaswamy
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry and Behavioral Sciences, SUNY Downstate Medical Center, Brooklyn, NY
| | - Niklas Manz
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry and Behavioral Sciences, SUNY Downstate Medical Center, Brooklyn, NY
| | - Jen-Chyong Wang
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO
| | - Leah Wetherill
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN
| | - Tony Hinrichs
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO
| | - Laura Almasy
- Department of Genetics, Texas Biomedical Research Institute, San Antonio, TX
| | - Andy Brooks
- Department of Genetics, Rutgers University, Piscataway, NJ
| | - David B. Chorlian
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry and Behavioral Sciences, SUNY Downstate Medical Center, Brooklyn, NY
| | - Danielle Dick
- Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, Richmond, VA
| | - Victor Hesselbrock
- Department of Psychiatry, University of Connecticut Health Center, Farmington, CT
| | - John Kramer
- Department of Psychiatry, University of Iowa College of Medicine, Iowa City, IA
| | - Sam Kuperman
- Department of Psychiatry, University of Iowa College of Medicine, Iowa City, IA
| | - John Nurnberger
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN
| | - John Rice
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO
| | - Marc Schuckit
- Department of Psychiatry, University of California-San Diego, La Jolla, CA
| | - Jay Tischfield
- Department of Genetics, Rutgers University, Piscataway, NJ
| | - Laura J. Bierut
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO
| | - Howard J. Edenberg
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN
| | - Alison Goate
- Department of Psychiatry, Washington University School of Medicine, Saint Louis, MO
| | - Tatiana Foroud
- Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN
| | - Bernice Porjesz
- Henri Begleiter Neurodynamics Laboratory, Department of Psychiatry and Behavioral Sciences, SUNY Downstate Medical Center, Brooklyn, NY
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Lack of behavioral and cognitive effects of chronic ethosuximide and gabapentin treatment in the Ts65Dn mouse model of Down syndrome. Neuroscience 2012; 220:158-68. [PMID: 22728103 DOI: 10.1016/j.neuroscience.2012.06.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 06/06/2012] [Accepted: 06/13/2012] [Indexed: 11/22/2022]
Abstract
The Ts65Dn (TS) mouse model of Down syndrome (DS) displays a number of behavioral, neuromorphological and neurochemical phenotypes of the syndrome. Altered GABAergic transmission appears to contribute to the mechanisms responsible for the cognitive impairments in TS mice. Increased functional expression of the trisomic gene encoding an inwardly rectifying potassium channel, subfamily J, member 6 (KCNJ6) has been reported in DS and TS mice, along with the consequent impairment in GAB Aergic function. Partial display of DS phenotypes in mice harboring a single trisomy of Kcnj6 provides compelling evidence for a functional role of increased channel expression in some of the abnormal neurological phenotypes found in DS. Notably, the antiepileptic drug (AED) ethosuximide (ETH), but not other AEDs such as gabapentin (GAB), is known to inhibit KCNJ6 channels in mice. Here, we report the effect of chronic ETH and GAB on the behavioral and cognitive phenotypes of TS and disomic control (CO) mice. Neither drug significantly affected sensorimotor abilities, motor coordination or spontaneous activity in TS and CO mice. Also, ETH and GAB did not induce anxiety in the open field or plus maze tests, did not alter performance in the Morris water maze, and did not affect cued - or context - fear conditioning. Our results thus suggest that KCNJ6 may not be a promising drug target candidate in DS. As a corollary, they also show that long-term use of ETH and GAB is devoid of adverse behavioral and cognitive effects.
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Towards therapeutic applications of arthropod venom k(+)-channel blockers in CNS neurologic diseases involving memory acquisition and storage. J Toxicol 2012; 2012:756358. [PMID: 22701481 PMCID: PMC3373146 DOI: 10.1155/2012/756358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 02/08/2012] [Indexed: 12/31/2022] Open
Abstract
Potassium channels are the most heterogeneous and widely distributed group of ion channels and play important functions in all cells, in both normal and pathological mechanisms, including learning and memory processes. Being fundamental for many diverse physiological processes, K+-channels are recognized as potential therapeutic targets in the treatment of several Central Nervous System (CNS) diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, schizophrenia, HIV-1-associated dementia, and epilepsy. Blockers of these channels are therefore potential candidates for the symptomatic treatment of these neuropathies, through their neurological effects. Venomous animals have evolved a wide set of toxins for prey capture and defense. These compounds, mainly peptides, act on various pharmacological targets, making them an innumerable source of ligands for answering experimental paradigms, as well as for therapeutic application. This paper provides an overview of CNS K+-channels involved in memory acquisition and storage and aims at evaluating the use of highly selective K+-channel blockers derived from arthropod venoms as potential therapeutic agents for CNS diseases involving learning and memory mechanisms.
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43
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Li N, Zhang D, Zhang J, Guo Y, Yan Z, Wang H, Zhou L, Hong J, Wang X, A Z. Influence of age on the association of GIRK4 with metabolic syndrome. Ann Clin Biochem 2012; 49:369-76. [PMID: 22645387 DOI: 10.1258/acb.2011.011129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND G protein-coupled inward rectifier K+ channel 4 (GIRK4) gene expressions have been implicated in the development of obesity, a key feature of metabolic syndrome (MetS). We investigated whether sequence variants of GIRK4 may represent metabolic risk factors for the Uygur Chinese population. METHODS The entire GIRK4 gene, including all exons, the promoter and untranslated regions from 48 MetS individuals, was studied in order to identify genetic variations associated with the disorder. Targeted genotyping of four common single nucleotide polymorphisms (SNPs: rs11221497, rs6590357, rs4937391 and rs2604204) and one novel missense mutation (M210I) was performed using the TaqMan polymerase chain reaction method for 443 MetS and 786 non-MetS subjects. RESULTS When all MetS cases were compared against all non-MetS controls, no significant association was found between the three SNPs (rs2604204, rs4937391 and rs6590357) and MetS status or metabolic traits. After adjustment, rs11221497 was associated with MetS (odds ratio (OR) [95% CI]=0.731 [0.551-0.968], P=0.029). Interestingly, when the MetS group was stratified into subclasses by age, an association was found for the three SNPs (rs2604204, rs4937391 and rs6590357) having estimated false discovery rates<0.001 and age of <50 y. After adjustment, the SNPs rs2604204, rs4937391 and rs6590357 were also associated with MetS in younger subjects: ORs [95% CI]: 1.678 [1.149-2.450], 1.839 [1.204-2.809] and 0.602 [0.379-0.958], respectively. All of the four SNPs showed a trend towards lower or higher metabolic traits (P<0.05) in younger subjects. In addition, a newly identified missense mutation (M210I) was not specifically related with MetS. CONCLUSIONS GIRK4 sequence variants appear to associate with MetS in the Uygurian population, and this association may be influenced by age.
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Affiliation(s)
- Nanfang Li
- The Center of Hypertension of the People's Hospital of Xinjiang Uygur Autonomous Region, Xinjiang 830001, China.
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Kloukina V, Herzer S, Karlsson N, Perez M, Daraio T, Meister B. G-protein-gated inwardly rectifying K+ channel 4 (GIRK4) immunoreactivity in chemically defined neurons of the hypothalamic arcuate nucleus that control body weight. J Chem Neuroanat 2012; 44:14-23. [PMID: 22465809 DOI: 10.1016/j.jchemneu.2012.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 02/10/2012] [Accepted: 03/15/2012] [Indexed: 01/10/2023]
Abstract
G-protein-gated inwardly rectifying K(+) channels (GIRKs; also called Kir3) are a family of K(+) channels, which are activated (opened) via a signal transduction cascade starting with ligand-stimulated G-protein-coupled receptors (GPCRs). Four GIRK genes have been identified (GIRK1-4). GIRK4 (Kir3.4) has a role in regulating energy homeostasis, since mice with a targeted mutation in the GIRK4 gene exhibit a predisposition to late-onset obesity. GIRK4 mRNA is expressed in hypothalamic regions that harbor neurons involved in the regulation of food intake and body weight. Using goat and rabbit antisera to the GIRK4 protein, the cellular localization and transmitter content of GIRK4-immunoreactive neurons was determined in the hypothalamic arcuate nucleus, a region that contains neurons which are accessible to circulating hormones and is intimately associated with the control of body weight. GIRK4-immunoreactive large cell bodies were demonstrated in the ventrolateral part of the arcuate nucleus, with smaller neuronal cell bodies in the ventromedial part of the nucleus. Double-labeling showed presence of GIRK4 immunoreactivity in large neurons of the ventrolateral arcuate nucleus containing the peptides α-melanocyte-stimulating hormone (α-MSH), a marker for pro-opiomelanocortin (POMC) neurons, and cocaine- and amphetamine-regulated transcript (CART). GIRK4 immunoreactivity was also seen in neurons of the ventromedial part of the arcuate nucleus containing agouti-regulated peptide (AgRP) and neuropeptide Y (NPY). The results suggest that the GIRK4 channel protein plays a role in regulating membrane excitability in chemically defined neurons of the arcuate nucleus that control body weight.
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Affiliation(s)
- Vaia Kloukina
- Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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45
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Rangani RJ, Upadhya MA, Nakhate KT, Kokare DM, Subhedar NK. Nicotine evoked improvement in learning and memory is mediated through NPY Y1 receptors in rat model of Alzheimer's disease. Peptides 2012; 33:317-28. [PMID: 22266216 DOI: 10.1016/j.peptides.2012.01.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 01/06/2012] [Accepted: 01/06/2012] [Indexed: 02/05/2023]
Abstract
We investigated the role of endogenous neuropeptide Y (NPY) system in nicotine-mediated improvement of learning and memory in rat model of Alzheimer's disease (AD). Intracerebroventricular (icv) colchicine treatment induced AD-like condition in rats and showed increased escape latency (decreased learning), and amnesic condition in probe test in Morris water maze. In these rats, nicotine (0.5mg/kg, intraperitoneal), NPY (100 ng/rat, icv) or NPY Y1 receptor agonist [Leu(31), Pro(34)]-NPY (0.04 ng/rat, icv) decreased escape latency by 54.76%, 55.81% and 44.18%, respectively, on day 4 of the acquisition. On the other hand, selective NPY Y1 receptor antagonist, BIBP3226 (icv) produced opposite effect (44.18%). In the probe test conducted at 24h time point, nicotine, NPY or [Leu(31), Pro(34)]-NPY increased the time spent by 72.72%, 44.11% and 26.47%, respectively; while BIBP3226 caused reduction (8.82%). It seems that while NPY or [Leu(31), Pro(34)]-NPY potentiated, BIBP3226 attenuated the learning and memory enhancing effects of nicotine. Brains of colchicine treated rats showed significant reduction in NPY-immunoreactivity in the nucleus accumbens shell (cells 62.23% and fibers 50%), bed nucleus of stria terminalis (fibers 71.58%), central nucleus of amygdala (cells 74.33%), arcuate nucleus (cells 70.97% and fibers 69.65%) and dentate gyrus (cells 58.54%). However, in these rats nicotine treatment for 4 days restored NPY-immunoreactivity to the control level. We suggest that NPY, perhaps acting via NPY Y1 receptors, might interact with the endogenous cholinergic system and play a role in improving the learning and memory processes in the rats with AD-like condition.
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Affiliation(s)
- Ritesh J Rangani
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University Campus, Nagpur 440 033, India
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Yu JZ, Rasenick MM. Receptor signaling and the cell biology of synaptic transmission. HANDBOOK OF CLINICAL NEUROLOGY 2012; 106:9-35. [PMID: 22608613 DOI: 10.1016/b978-0-444-52002-9.00002-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
This volume describes a series of psychiatric and neuropsychiatric disorders, connects some aspects of somatic and psychiatric medicine, and describes various current and emerging therapies. The purpose of this chapter is to set the stage for the volume by developing the theoretical basis of synaptic transmission and introducing the various neurotransmitters and their receptors involved in the process. The intent is to provide not only a historical context through which to understand neurotransmitters, but a current contextual basis for understanding neuronal signal transduction and applying this knowledge to facilitate treatment of maladies of the brain and mind.
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Affiliation(s)
- Jiang-Zhou Yu
- Department of Physiology, University of Illinois, Chicago, IL, USA
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47
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Fernández-Alacid L, Watanabe M, Molnár E, Wickman K, Luján R. Developmental regulation of G protein-gated inwardly-rectifying K+ (GIRK/Kir3) channel subunits in the brain. Eur J Neurosci 2011; 34:1724-36. [PMID: 22098295 DOI: 10.1111/j.1460-9568.2011.07886.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
G protein-gated inwardly-rectifying K(+) (GIRK/family 3 of inwardly-rectifying K(+) ) channels are coupled to neurotransmitter action and can play important roles in modulating neuronal excitability. We investigated the temporal and spatial expression of GIRK1, GIRK2 and GIRK3 subunits in the developing and adult brain of mice and rats using biochemical, immunohistochemical and immunoelectron microscopic techniques. At all ages analysed, the overall distribution patterns of GIRK1-3 were very similar, with high expression levels in the neocortex, cerebellum, hippocampus and thalamus. Focusing on the hippocampus, histoblotting and immunohistochemistry showed that GIRK1-3 protein levels increased with age, and this was accompanied by a shift in the subcellular localization of the subunits. Early in development (postnatal day 5), GIRK subunits were predominantly localized to the endoplasmic reticulum in the pyramidal cells, but by postnatal day 60 they were mostly found along the plasma membrane. During development, GIRK1 and GIRK2 were found primarily at postsynaptic sites, whereas GIRK3 was predominantly detected at presynaptic sites. In addition, GIRK1 and GIRK2 expression on the spine plasma membrane showed identical proximal-to-distal gradients that differed from GIRK3 distribution. Furthermore, although GIRK1 was never found within the postsynaptic density (PSD), the level of GIRK2 in the PSD progressively increased and GIRK3 did not change in the PSD during development. Together, these findings shed new light on the developmental regulation and subcellular diversity of neuronal GIRK channels, and support the contention that distinct subpopulations of GIRK channels exert separable influences on neuronal excitability. The ability to selectively target specific subpopulations of GIRK channels may prove effective in the treatment of disorders of excitability.
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Affiliation(s)
- Laura Fernández-Alacid
- Departamento de Ciencias Médicas, Facultad de Medicina, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Universidad de Castilla-La Mancha, Albacete, Spain
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YAMAMOTO G, SOEDA F, SHIRASAKI T, TAKAHAMA K. Is the GIRK Channel a Possible Target in the Development of a Novel Therapeutic Drug of Urinary Disturbance? YAKUGAKU ZASSHI 2011; 131:523-32. [DOI: 10.1248/yakushi.131.523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Gen YAMAMOTO
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Fumio SOEDA
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Tetsuya SHIRASAKI
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
| | - Kazuo TAKAHAMA
- Department of Environmental and Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University
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49
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Abstract
The developing mammalian cerebral cortex contains a distinct class of cells, subplate neurons (SPns), that play an important role during early development. SPns are the first neurons to be generated in the cerebral cortex, they reside in the cortical white matter, and they are the first to mature physiologically. SPns receive thalamic and neuromodulatory inputs and project into the developing cortical plate, mostly to layer 4. Thus SPns form one of the first functional cortical circuits and are required to relay early oscillatory activity into the developing cortical plate. Pathophysiological impairment or removal of SPns profoundly affects functional cortical development. SPn removal in visual cortex prevents the maturation of thalamocortical synapses, the maturation of inhibition in layer 4, the development of orientation selective responses and the formation of ocular dominance columns. SPn removal also alters ocular dominance plasticity during the critical period. Therefore, SPns are a key regulator of cortical development and plasticity. SPns are vulnerable to injury during prenatal stages and might provide a crucial link between brain injury in development and later cognitive malfunction.
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Affiliation(s)
- Patrick O Kanold
- Department of Biology, University of Maryland, College Park, Maryland 20742, USA.
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50
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Upadhya MA, Nakhate KT, Kokare DM, Singru PS, Subhedar NK. Cocaine- and amphetamine-regulated transcript peptide increases spatial learning and memory in rats. Life Sci 2010; 88:322-34. [PMID: 21167182 DOI: 10.1016/j.lfs.2010.12.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 10/29/2010] [Accepted: 12/01/2010] [Indexed: 10/18/2022]
Abstract
AIM We investigated the involvement of cocaine- and amphetamine-regulated transcript peptide (CART) in spatial learning and memory. MAIN METHODS Rats were intracerebroventricularly injected with CART or CART-antibody, with or without intraperitoneal scopolamine, for a period of 4 days, during which they were subjected to the acquisition protocol in Morris water maze (MWM). In retrieval protocols, at 24 h and 15 days post-acquisition time points similar treatments were given to trained rats and subjected to MWM. The response of endogenous CART system to the training as well as retrieval sessions in MWM was evaluated with immunohistochemistry. KEY FINDINGS CART-administered rats showed a significant reduction in escape latency from day 1 through 4 days of acquisition; the rats spent more time in the platform quadrant in MWM during the retrieval protocol. CART-antibody or scopolamine produced an opposite effect. The effects of scopolamine were attenuated by CART, and potentiated by CART-antibody. CART-immunoreactivity in the arcuate and paraventricular nuclei, central nucleus of amygdala, bed nucleus of stria terminalis, accumbens shell, dentate gyrus (DG), and thalamic paraventricular nucleus (PVT), but not in the cornu ammonis 1-3 of hippocampus, was significantly increased following 4 days of training, and at 24 h retrieval time point in MWM. The changes were blocked by scopolamine. At 15 days retrieval time point, the immunoreactivity profiles resembled those in naïve control. SIGNIFICANCE While CART seems to promote spatial learning and memory, navigational experiences in MWM up regulates the endogenous CART systems in extended amygdala, hypothalamus, DG and PVT.
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Affiliation(s)
- Manoj A Upadhya
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University Campus, Nagpur-440 033, India
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