1
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Prytkova I, Liu Y, Fernando M, Gameiro-Ros I, Popova D, Kamarajan C, Xuei X, Chorlian DB, Edenberg HJ, Tischfield JA, Porjesz B, Pang ZP, Hart RP, Goate A, Slesinger PA. Upregulated GIRK2 counteracts ethanol-induced changes in excitability & respiration in human neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.03.22.533236. [PMID: 36993693 PMCID: PMC10055374 DOI: 10.1101/2023.03.22.533236] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Genome-wide association analysis (GWAS) of electroencephalographic endophenotypes for alcohol use disorder (AUD) has identified non-coding polymorphisms within the KCNJ6 gene. KCNJ6 encodes GIRK2, a subunit of a G protein-coupled inwardly-rectifying potassium channel that regulates neuronal excitability. How changes in GIRK2 affect human neuronal excitability and the response to repeated ethanol exposure is poorly understood. Here, we studied the effect of upregulating KCNJ6 using an isogenic approach with human glutamatergic neurons derived from induced pluripotent stem cells (male and female donors). Using multi-electrode-arrays, population calcium imaging, single-cell patch-clamp electrophysiology, and mitochondrial stress tests, we find that elevated GIRK2 acts in concert with 7-21 days of ethanol exposure to inhibit neuronal activity, to counteract ethanol-induced increases in glutamate response, and to promote an increase intrinsic excitability. Furthermore, elevated GIRK2 prevented ethanol-dependent changes in basal and activity-dependent mitochondrial respiration. These data support a role for GIRK2 in mitigating the effects of ethanol and a previously unknown connection to mitochondrial function in human glutamatergic neurons. SIGNIFICANCE STATEMENT Alcohol use disorder (AUD) is a major health problem that has worsened since COVID, affecting over 100 million people worldwide. While it is known that heritability contributes to AUD, specific genes and their role in neuronal function remain poorly understood, especially in humans. In the current manuscript, we focused on the inwardly-rectifying potassium channel GIRK2, which has been identified in an AUD-endophenotype genome-wide association study. We used human excitatory neurons derived from healthy donors to study the impact of GIRK2 expression. Our results reveal that elevated GIRK2 counteracts ethanol-induced increases in glutamate response and intracellular calcium, as well as deficits in activity-dependent mitochondrial respiration. The role of GIRK2 in mitigating ethanol-induced hyper-glutamatergic and mitochondrial offers therapeutic promise for treating AUD.
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2
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Yang L, Shi LJ, Shen SY, Yang JY, Lv SS, Wang ZC, Huang Q, Xu WD, Yu J, Zhang YQ. Toward Antifragility: Social Defeat Stress Enhances Learning and Memory in Young Mice Via Hippocampal Synaptosome Associated Protein 25. Psychol Sci 2023; 34:616-632. [PMID: 37040450 DOI: 10.1177/09567976231160098] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023] Open
Abstract
Social adversity not only causes severe psychological diseases but also may improve people's ability to learn and grow. However, the beneficial effects of social adversity are often ignored. In this study, we investigated whether and how social adversity affects learning and memory in a mouse social defeat stress (SDS) model. A total of 652 mice were placed in experimental groups of six to 23 mice each. SDS enhanced spatial, novelty, and fear memory with increased synaptosome associated protein 25 (SNAP-25) level and dendritic spine density in hippocampal neurons among young but not middle-aged mice. Chemogenetic inhibition of hippocampal CaMK2A+ neurons blocked SDS-induced enhancement of learning or memory. Knockdown of SNAP-25 or blockade of N-methyl-D-aspartate (NMDA) receptor subunit GluN2B in the hippocampus prevented SDS-induced learning memory enhancement in an emotion-independent manner. These findings suggest that social adversity promotes learning and memory ability in youths and provide a neurobiological foundation for biopsychological antifragility.
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Affiliation(s)
- Liu Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
| | - Li-Jun Shi
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
| | - Shi-Yu Shen
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University
| | - Jing-Yan Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
| | - Su-Su Lv
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
| | - Zhe-Chen Wang
- Department of Psychology, School of Social Development and Public Policy, Fudan University
- School of Psychology, The University of Queensland
| | - Qian Huang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
| | - Wen-Dong Xu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
- Department of Hand Surgery, Huashan Hospital, Fudan University
| | - Jin Yu
- Department of Integrative Medicine and Neurobiology, State Key Laboratory of Medical Neurobiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University
| | - Yu-Qiu Zhang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Translational Neuroscience, Jing'an District Centre Hospital of Shanghai, Institutes of Brain Science, Fudan University
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3
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Popova D, Gameiro-Ros I, Youssef MM, Zalamea P, Morris AD, Prytkova I, Jadali A, Kwan KY, Kamarajan C, Salvatore JE, Xuei X, Chorlian DB, Porjesz B, Kuperman S, Dick DM, Goate A, Edenberg HJ, Tischfield JA, Pang ZP, Slesinger PA, Hart RP. Alcohol reverses the effects of KCNJ6 (GIRK2) noncoding variants on excitability of human glutamatergic neurons. Mol Psychiatry 2023; 28:746-758. [PMID: 36207584 PMCID: PMC9542475 DOI: 10.1038/s41380-022-01818-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 01/19/2023]
Abstract
Synonymous and noncoding single nucleotide polymorphisms (SNPs) in the KCNJ6 gene, encoding G protein-gated inwardly rectifying potassium channel subunit 2 (GIRK2), have been linked with increased electroencephalographic frontal theta event-related oscillations (ERO) in subjects diagnosed with alcohol use disorder (AUD). To identify molecular and cellular mechanisms while retaining the appropriate genetic background, we generated induced excitatory glutamatergic neurons (iN) from iPSCs derived from four AUD-diagnosed subjects with KCNJ6 variants ("Affected: AF") and four control subjects without variants ("Unaffected: UN"). Neurons were analyzed for changes in gene expression, morphology, excitability and physiological properties. Single-cell RNA sequencing suggests that KCNJ6 AF variant neurons have altered patterns of synaptic transmission and cell projection morphogenesis. Results confirm that AF neurons express lower levels of GIRK2, have greater neurite area, and elevated excitability. Interestingly, exposure to intoxicating concentrations of ethanol induces GIRK2 expression and reverses functional effects in AF neurons. Ectopic overexpression of GIRK2 alone mimics the effect of ethanol to normalize induced excitability. We conclude that KCNJ6 variants decrease GIRK2 expression and increase excitability and that this effect can be minimized or reduced with ethanol.
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Affiliation(s)
- Dina Popova
- Human Genetics Institute, Rutgers University, Piscataway, NJ, USA
| | - Isabel Gameiro-Ros
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mark M Youssef
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, NJ, USA
| | - Petronio Zalamea
- Human Genetics Institute, Rutgers University, Piscataway, NJ, USA
| | - Ayeshia D Morris
- Joint Program in Toxicology, Rutgers University, Piscataway, NJ, USA
| | - Iya Prytkova
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Azadeh Jadali
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, NJ, USA
| | - Kelvin Y Kwan
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, NJ, USA
| | - Chella Kamarajan
- Dept. of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Jessica E Salvatore
- Department of Psychiatry, Rutgers Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| | - Xiaoling Xuei
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - David B Chorlian
- Dept. of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Bernice Porjesz
- Dept. of Psychiatry & Behavioral Sciences, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Samuel Kuperman
- Department of Psychiatry, University of Iowa Carver College of Medicine, Iowa City, IA, USA
| | - Danielle M Dick
- Rutgers Addiction Research Center, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
| | - Alison Goate
- Department of Genetics & Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Howard J Edenberg
- Department of Biochemistry and Molecular Biology, Indiana Univ School of Medicine, Indianapolis, IN, USA
| | - Jay A Tischfield
- Human Genetics Institute, Rutgers University, Piscataway, NJ, USA
| | - Zhiping P Pang
- Human Genetics Institute, Rutgers University, Piscataway, NJ, USA
- Child Health Institute, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ, USA
| | - Paul A Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ronald P Hart
- Human Genetics Institute, Rutgers University, Piscataway, NJ, USA.
- Department of Cell Biology & Neuroscience, Rutgers University, Piscataway, NJ, USA.
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4
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Kleschevnikov A. GIRK2 Channels in Down syndrome and Alzheimer's disease. Curr Alzheimer Res 2022; 19:CAR-EPUB-128417. [PMID: 36567290 DOI: 10.2174/1567205020666221223122110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 11/26/2022] [Accepted: 11/29/2022] [Indexed: 12/27/2022]
Abstract
Cognitive impairment in Down syndrome (DS) results from the abnormal expression of hundreds of genes. However, the impact of KCNJ6, a gene located in the middle of the 'Down syndrome critical region' of chromosome 21, seems to stand out. KCNJ6 encodes GIRK2 (KIR3.2) subunits of G protein-gated inwardly rectifying potassium channels, which serve as effectors for GABAB, m2, 5HT1A, A1, and many other postsynaptic metabotropic receptors. GIRK2 subunits are heavily expressed in neocortex, cerebellum, and hippocampus. By controlling resting membrane potential and neuronal excitability, GIRK2 channels may thus affect both synaptic plasticity and stability of neural circuits in the brain regions important for learning and memory. Here, we discuss recent experimental data regarding the role of KCNJ6/GIRK2 in neuronal abnormalities and cognitive impairment in models of DS and Aalzheimer's disease (AD). The results compellingly show that signaling through GIRK2 channels is abnormally enhanced in mouse genetic models of Down syndrome and that partial suppression of GIRK2 channels with pharmacological or genetic means can restore synaptic plasticity and improve impaired cognitive functions. On the other hand, signaling through GIRK2 channels is downregulated in AD models, such as models of early amyloidopathy. In these models, reduced GIRK2 channel signaling promotes neuronal hyperactivity, causing excitatory-inhibitory imbalance and neuronal death. Accordingly, activation of GABAB/GIRK2 signaling by GIRK channel activators or GABAB receptor agonists may reduce Aβ-induced hyperactivity and subsequent neuronal death, thereby exerting a neuroprotective effect in models of AD.
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5
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Spatial Memory Training Counteracts Hippocampal GIRK Channel Decrease in the Transgenic APPSw,Ind J9 Alzheimer’s Disease Mouse Model. Int J Mol Sci 2022; 23:ijms232113444. [PMID: 36362230 PMCID: PMC9659077 DOI: 10.3390/ijms232113444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 10/21/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
G-protein-gated inwardly rectifying potassium (GIRK) channels are critical determinants of neuronal excitability. They have been proposed as potential targets to restore excitatory/inhibitory balance in acute amyloidosis models, where hyperexcitability is a hallmark. However, the role of GIRK signaling in transgenic mice models of Alzheimer’s disease (AD) is largely unknown. Here, we study whether progressive amyloid-β (Aβ) accumulation in the hippocampus during aging alters GIRK channel expression in mutant β-amyloid precursor protein (APPSw,Ind J9) transgenic AD mice. Additionally, we examine the impact of spatial memory training in a hippocampal-dependent task, on protein expression of GIRK subunits and Regulator of G-protein signaling 7 (RGS7) in the hippocampus of APPSw,Ind J9 mice. Firstly, we found a reduction in GIRK2 expression (the main neuronal GIRK channels subunit) in the hippocampus of 6-month-old APPSw,Ind J9 mice. Moreover, we found an aging effect on GIRK2 and GIRK3 subunits in both wild type (WT) and APPSw,Ind J9 mice. Finally, when 6-month-old animals were challenged to a spatial memory training, GIRK2 expression in the APPSw,Ind J9 mice were normalized to WT levels. Together, our results support the evidence that GIRK2 could account for the excitatory/inhibitory neurotransmission imbalance found in AD models, and training in a cognitive hippocampal dependent task may have therapeutic benefits of reversing this effect and lessen early AD deficits.
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6
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Kleschevnikov AM. Enhanced GIRK2 channel signaling in Down syndrome: A feasible role in the development of abnormal nascent neural circuits. Front Genet 2022; 13:1006068. [PMID: 36171878 PMCID: PMC9510977 DOI: 10.3389/fgene.2022.1006068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/24/2022] [Indexed: 11/24/2022] Open
Abstract
The most distinctive feature of Down syndrome (DS) is moderate to severe cognitive impairment. Genetic, molecular, and neuronal mechanisms of this complex DS phenotype are currently under intensive investigation. It is becoming increasingly clear that the abnormalities arise from a combination of initial changes caused by triplication of genes on human chromosome 21 (HSA21) and later compensatory adaptations affecting multiple brain systems. Consequently, relatively mild initial cognitive deficits become pronounced with age. This pattern of changes suggests that one approach to improving cognitive function in DS is to target the earliest critical changes, the prevention of which can change the ‘trajectory’ of the brain development and reduce the destructive effects of the secondary alterations. Here, we review the experimental data on the role of KCNJ6 in DS-specific brain abnormalities, focusing on a putative role of this gene in the development of abnormal neural circuits in the hippocampus of genetic mouse models of DS. It is suggested that the prevention of these early abnormalities with pharmacological or genetic means can ameliorate cognitive impairment in DS.
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7
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Luo H, Marron Fernandez de Velasco E, Wickman K. Neuronal G protein-gated K + channels. Am J Physiol Cell Physiol 2022; 323:C439-C460. [PMID: 35704701 PMCID: PMC9362898 DOI: 10.1152/ajpcell.00102.2022] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels exert a critical inhibitory influence on neurons. Neuronal GIRK channels mediate the G protein-dependent, direct/postsynaptic inhibitory effect of many neurotransmitters including γ-aminobutyric acid (GABA), serotonin, dopamine, adenosine, somatostatin, and enkephalin. In addition to their complex regulation by G proteins, neuronal GIRK channel activity is sensitive to PIP2, phosphorylation, regulator of G protein signaling (RGS) proteins, intracellular Na+ and Ca2+, and cholesterol. The application of genetic and viral manipulations in rodent models, together with recent progress in the development of GIRK channel modulators, has increased our understanding of the physiological and behavioral impact of neuronal GIRK channels. Work in rodent models has also revealed that neuronal GIRK channel activity is modified, transiently or persistently, by various stimuli including exposure drugs of abuse, changes in neuronal activity patterns, and aversive experience. A growing body of preclinical and clinical evidence suggests that dysregulation of GIRK channel activity contributes to neurological diseases and disorders. The primary goals of this review are to highlight fundamental principles of neuronal GIRK channel biology, mechanisms of GIRK channel regulation and plasticity, the nascent landscape of GIRK channel pharmacology, and the potential relevance of GIRK channels to the pathophysiology and treatment of neurological diseases and disorders.
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Affiliation(s)
- Haichang Luo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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8
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Park J, Farris S. Spatiotemporal Regulation of Transcript Isoform Expression in the Hippocampus. Front Mol Neurosci 2021; 14:694234. [PMID: 34305526 PMCID: PMC8295539 DOI: 10.3389/fnmol.2021.694234] [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: 04/12/2021] [Accepted: 06/15/2021] [Indexed: 11/13/2022] Open
Abstract
Proper development and plasticity of hippocampal neurons require specific RNA isoforms to be expressed in the right place at the right time. Precise spatiotemporal transcript regulation requires the incorporation of essential regulatory RNA sequences into expressed isoforms. In this review, we describe several RNA processing strategies utilized by hippocampal neurons to regulate the spatiotemporal expression of genes critical to development and plasticity. The works described here demonstrate how the hippocampus is an ideal investigative model for uncovering alternate isoform-specific mechanisms that restrict the expression of transcripts in space and time.
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Affiliation(s)
- Joun Park
- Fralin Biomedical Research Institute, Center for Neurobiology Research, Virginia Tech Carilion, Roanoke, VA, United States
| | - Shannon Farris
- Fralin Biomedical Research Institute, Center for Neurobiology Research, Virginia Tech Carilion, Roanoke, VA, United States.,Department of Biomedical Sciences and Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.,Virginia Tech Carilion School of Medicine, Roanoke, VA, United States
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9
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Weaver CD, Denton JS. Next-generation inward rectifier potassium channel modulators: discovery and molecular pharmacology. Am J Physiol Cell Physiol 2021; 320:C1125-C1140. [PMID: 33826405 DOI: 10.1152/ajpcell.00548.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inward rectifying potassium (Kir) channels play important roles in both excitable and nonexcitable cells of various organ systems and could represent valuable new drug targets for cardiovascular, metabolic, immune, and neurological diseases. In nonexcitable epithelial cells of the kidney tubule, for example, Kir1.1 (KCNJ1) and Kir4.1 (KCNJ10) are linked to sodium reabsorption in the thick ascending limb of Henle's loop and distal convoluted tubule, respectively, and have been explored as novel-mechanism diuretic targets for managing hypertension and edema. G protein-coupled Kir channels (Kir3) channels expressed in the central nervous system are critical effectors of numerous signal transduction pathways underlying analgesia, addiction, and respiratory-depressive effects of opioids. The historical dearth of pharmacological tool compounds for exploring the therapeutic potential of Kir channels has led to a molecular target-based approach using high-throughput screen (HTS) of small-molecule libraries and medicinal chemistry to develop "next-generation" Kir channel modulators that are both potent and specific for their targets. In this article, we review recent efforts focused specifically on discovery and improvement of target-selective molecular probes. The reader is introduced to fluorescence-based thallium flux assays that have enabled much of this work and then provided with an overview of progress made toward developing modulators of Kir1.1 (VU590, VU591), Kir2.x (ML133), Kir3.X (ML297, GAT1508, GiGA1, VU059331), Kir4.1 (VU0134992), and Kir7.1 (ML418). We discuss what is known about the small molecules' molecular mechanisms of action, in vitro and in vivo pharmacology, and then close with our view of what critical work remains to be done.
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Affiliation(s)
- C David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee.,Department of Chemistry, Vanderbilt University, Nashville, Tennessee.,Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee
| | - Jerod S Denton
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee.,Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee.,Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee
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10
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Johnson CM, Cui N, Xing H, Wu Y, Jiang C. The antitussive cloperastine improves breathing abnormalities in a Rett Syndrome mouse model by blocking presynaptic GIRK channels and enhancing GABA release. Neuropharmacology 2020; 176:108214. [PMID: 32622786 DOI: 10.1016/j.neuropharm.2020.108214] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 06/12/2020] [Accepted: 06/14/2020] [Indexed: 12/21/2022]
Abstract
Rett Syndrome (RTT) is an X-linked neurodevelopmental disorder caused mainly by mutations in the MECP2 gene. One of the major RTT features is breathing dysfunction characterized by periodic hypo- and hyperventilation. The breathing disorders are associated with increased brainstem neuronal excitability, which can be alleviated with GABA agonists. Since neuronal hypoexcitability occurs in the forebrain of RTT models, it is necessary to find pharmacological agents with a relative preference to brainstem neurons. Here we show evidence for the improvement of breathing disorders of Mecp2-disrupted mice with the brainstem-acting drug cloperastine (CPS) and its likely neuronal targets. CPS is an over-the-counter cough medicine that has an inhibitory effect on brainstem neuronal networks. In Mecp2-disrupted mice, CPS (30 mg/kg, i.p.) decreased the occurrence of apneas/h and breath frequency variation. GIRK currents expressed in HEK cells were inhibited by CPS with IC50 1 μM. Whole-cell patch clamp recordings in locus coeruleus (LC) and dorsal tegmental nucleus (DTN) neurons revealed an overall inhibitory effect of CPS (10 μM) on neuronal firing activity. Such an effect was reversed by the GABAA receptor antagonist bicuculline (20 μM). Voltage clamp studies showed that CPS increased GABAergic sIPSCs in LC cells, which was blocked by the GABAB receptor antagonist phaclofen. Functional GABAergic connections of DTN neurons with LC cells were shown. These results suggest that CPS improves breathing dysfunction in Mecp2-null mice by blocking GIRK channels in synaptic terminals and enhancing GABA release.
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Affiliation(s)
- Christopher M Johnson
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Ningren Cui
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Hao Xing
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Yang Wu
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Chun Jiang
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA.
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11
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Anderson A, Masuho I, Marron Fernandez de Velasco E, Nakano A, Birnbaumer L, Martemyanov KA, Wickman K. GPCR-dependent biasing of GIRK channel signaling dynamics by RGS6 in mouse sinoatrial nodal cells. Proc Natl Acad Sci U S A 2020; 117:14522-14531. [PMID: 32513692 PMCID: PMC7322085 DOI: 10.1073/pnas.2001270117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
How G protein-coupled receptors (GPCRs) evoke specific biological outcomes while utilizing a limited array of G proteins and effectors is poorly understood, particularly in native cell systems. Here, we examined signaling evoked by muscarinic (M2R) and adenosine (A1R) receptor activation in the mouse sinoatrial node (SAN), the cardiac pacemaker. M2R and A1R activate a shared pool of cardiac G protein-gated inwardly rectifying K+ (GIRK) channels in SAN cells from adult mice, but A1R-GIRK responses are smaller and slower than M2R-GIRK responses. Recordings from mice lacking Regulator of G protein Signaling 6 (RGS6) revealed that RGS6 exerts a GPCR-dependent influence on GIRK-dependent signaling in SAN cells, suppressing M2R-GIRK coupling efficiency and kinetics and A1R-GIRK signaling amplitude. Fast kinetic bioluminescence resonance energy transfer assays in transfected HEK cells showed that RGS6 prefers Gαo over Gαi as a substrate for its catalytic activity and that M2R signals preferentially via Gαo, while A1R does not discriminate between inhibitory G protein isoforms. The impact of atrial/SAN-selective ablation of Gαo or Gαi2 was consistent with these findings. Gαi2 ablation had minimal impact on M2R-GIRK and A1R-GIRK signaling in SAN cells. In contrast, Gαo ablation decreased the amplitude and slowed the kinetics of M2R-GIRK responses, while enhancing the sensitivity and prolonging the deactivation rate of A1R-GIRK signaling. Collectively, our data show that differences in GPCR-G protein coupling preferences, and the Gαo substrate preference of RGS6, shape A1R- and M2R-GIRK signaling dynamics in mouse SAN cells.
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Affiliation(s)
- Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
| | | | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
- Biomedical Research Institute, Catholic University of Argentina, C1107AAZ Buenos Aires, Argentina
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455;
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12
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Zou B, Cao WS, Guan Z, Xiao K, Pascual C, Xie J, Zhang J, Xie J, Kayser F, Lindsley CW, Weaver CD, Fang J, Xie XS. Direct activation of G-protein-gated inward rectifying K+ channels promotes nonrapid eye movement sleep. Sleep 2020; 42:5238085. [PMID: 30535004 DOI: 10.1093/sleep/zsy244] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 11/16/2018] [Accepted: 12/06/2018] [Indexed: 12/26/2022] Open
Abstract
STUDY OBJECTIVES A major challenge in treating insomnia is to find effective medicines with fewer side effects. Activation of G-protein-gated inward rectifying K+ channels (GIRKs) by GABAB agonists baclofen or γ-hydroxybutyric acid (GHB) promotes nonrapid eye movement (NREM) sleep and consolidates sleep. However, baclofen has poor brain penetration, GHB possesses abuse liability, and in rodents both drugs cause spike-wave discharges (SWDs), an absence seizure activity. We tested the hypothesis that direct GIRK activation promotes sleep without inducing SWD using ML297, a potent and selective GIRK activator. METHODS Whole-cell patch-clamp recordings from hypocretin/orexin or hippocampal neurons in mouse brain slices were made to study neuronal excitability and synaptic activity; spontaneous activity, locomotion, contextual and tone-conditioned memory, and novel object recognition were assessed. Electroencephalogram/electromyogram (EEG/EMG) recordings were used to study GIRK modulation of sleep. RESULTS ML297, like baclofen, caused membrane hyperpolarization, decreased input resistance, and blockade of spontaneous action potentials. Unlike baclofen, ML297 (5-10 µM) did not cause significant depression of postsynaptic excitatory and inhibitory currents (EPSCs-IPSCs), indicating preferential postsynaptic inhibition. ML297 (30 mg/kg, i.p.) inhibited wake activity and locomotion, and preferentially increased NREM sleep without altering EEG delta power, REM sleep, inducing SWDs, or impairing conditioned memory and novel object recognition. CONCLUSIONS This study finds that direct activation of neuronal GIRK channels modulates postsynaptic membrane excitability and prolongs NREM sleep without changing sleep intensity, inducing SWDs, or impairing memory in rodents. These results suggest that direct GIRK activation with a selective compound may present an innovative approach for the treatment of chronic insomnia.
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Affiliation(s)
- Bende Zou
- AfaSci Research Laboratories, Redwood City, CA
| | | | - Zhiwei Guan
- Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA
| | - Kui Xiao
- AfaSci Research Laboratories, Redwood City, CA
| | | | - Julian Xie
- AfaSci Research Laboratories, Redwood City, CA
| | | | - James Xie
- AfaSci Research Laboratories, Redwood City, CA
| | | | - Craig W Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, TN
| | - C David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN
| | - Jidong Fang
- Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA
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13
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Goswamee P, McQuiston AR. Acetylcholine Release Inhibits Distinct Excitatory Inputs Onto Hippocampal CA1 Pyramidal Neurons via Different Cellular and Network Mechanisms. Front Cell Neurosci 2019; 13:267. [PMID: 31249513 PMCID: PMC6582433 DOI: 10.3389/fncel.2019.00267] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/29/2019] [Indexed: 12/13/2022] Open
Abstract
In hippocampal CA1, muscarinic acetylcholine (ACh) receptor (mAChR) activation via exogenous application of cholinergic agonists has been shown to presynaptically inhibit Schaffer collateral (SC) glutamatergic inputs in stratum radiatum (SR), and temporoammonic (TA) and thalamic nucleus reuniens (RE) glutamatergic inputs in stratum lacunosum-moleculare (SLM). However, steady-state uniform mAChR activation may not mimic the effect of ACh release in an intact hippocampal network. To more accurately examine the effect of ACh release on glutamatergic synaptic efficacy, we measured electrically evoked synaptic responses in CA1 pyramidal cells (PCs) following the optogenetic release of ACh in genetically modified mouse brain slices. The ratio of synaptic amplitudes in response to paired-pulse SR stimulation (stimulus 2/stimulus 1) was significantly reduced by the optogenetic release of ACh, consistent with a postsynaptic decrease in synaptic efficacy. The effect of ACh release was blocked by the M3 receptor antagonist 4-DAMP, the GABAB receptor antagonist CGP 52432, inclusion of GDP-β-S, cesium, QX314 in the intracellular patch clamp solution, or extracellular barium. These observations suggest that ACh release decreased SC synaptic transmission through an M3 muscarinic receptor-mediated increase in inhibitory interneuron excitability, which activate GABAB receptors and inwardly rectifying potassium channels on CA1 pyramidal cells. In contrast, the ratio of synaptic amplitudes in response to paired-pulse stimulation in the SLM was increased by ACh release, consistent with presynaptic inhibition. ACh-mediated effects in SLM were blocked by the M2 receptor antagonist AF-DX 116, presumably located on presynaptic terminals. Therefore, our data indicate that ACh release differentially modulates excitatory inputs in SR and SLM of CA1 through different cellular and network mechanisms.
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Affiliation(s)
- Priyodarshan Goswamee
- Department of Anatomy and Neurobiology, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
| | - A Rory McQuiston
- Department of Anatomy and Neurobiology, School of Medicine, Virginia Commonwealth University, Richmond, VA, United States
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14
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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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15
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Constantin S, Wray S. Nociceptin/Orphanin-FQ Inhibits Gonadotropin-Releasing Hormone Neurons via G-Protein-Gated Inwardly Rectifying Potassium Channels. eNeuro 2018; 5:ENEURO.0161-18.2018. [PMID: 30627649 PMCID: PMC6325553 DOI: 10.1523/eneuro.0161-18.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 12/18/2022] Open
Abstract
The pulsatile release of gonadotropin-releasing hormone (GnRH) is a key feature of the hypothalamic-pituitary-gonadal axis. Kisspeptin neurons in the arcuate nucleus (ARC) trigger GnRH neuronal activity, but how GnRH neurons return to baseline electrical activity is unknown. Nociceptin/orphanin-FQ (OFQ) is an inhibitory neuromodulator. ARC proopiomelanocortin (POMC) neurons, known to receive inputs from ARC kisspeptin neurons, contact GnRH neurons and coexpress OFQ in the rat. In the present study, the effect of OFQ(1-13) on GnRH neurons was determined in the mouse. We identified transcripts for the OFQ receptor [opioid receptor like 1 (ORL1)] in GnRH neurons, and, using two-model systems (explants and slices), we found that OFQ exerted a potent inhibition on GnRH neurons, with or without excitatory inputs. We confirmed that the inhibition was mediated by ORL1 via Gi/o-protein coupling. The inhibition, occurring independently of levels of intracellular cyclic adenosine monophosphate, was sensitive to inwardly rectifying potassium channels. The only specific blocker of Gi/o-protein-coupled inwardly rectifying potassium (GIRK) channels, tertiapin-Q (TPNQ), was ineffective in the inhibition of OFQ. Two GIRK activators, one sharing the binding site of TPNQ and one active only on GIRK1-containing GIRK channels, failed to trigger an inhibition. In contrast, protein kinase C phosphorylation activation, known to inhibit GIRK2-mediated currents, prevented the OFQ inhibition. These results indicate a specific combination of GIRK subunits, GIRK2/3 in GnRH neurons. In vivo, double-labeled OFQ/POMC fibers were found in the vicinity of GnRH neurons, and OFQ fibers apposed GnRH neurons. Together, this study brings to light a potent neuromodulator of GnRH neurons.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
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