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Li J, Mei S, Mao X, Wan L, Wang H, Xiao B, Song Y, Gu W, Liu Y, Long L. De novo variants in KCNJ3 are associated with early-onset epilepsy. J Med Genet 2024; 61:319-324. [PMID: 37963718 DOI: 10.1136/jmg-2023-109201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 10/14/2023] [Indexed: 11/16/2023]
Abstract
BACKGROUND KCNJ3 encodes a subunit of G-protein-coupled inwardly rectifying potassium channels, which are important for cellular excitability and inhibitory neurotransmission. However, the genetic basis of KCNJ3 in epilepsy has not been determined. This study aimed to identify the pathogenic KCNJ3 variants in patients with epilepsy. METHODS Trio exome sequencing was performed to determine potential variants of epilepsy. Individuals with KCNJ3 variants were recruited for this study. Detailed clinical information and genetic data were obtained and systematically reviewed. Whole-cell patch-clamp recordings were performed to evaluate the functional consequences of the identified variants. RESULTS Two de novo missense variants (c.998T>C (p.Leu333Ser) and c.938G>A (p. Arg313Gln)) in KCNJ3 were identified in two unrelated families with epilepsy. The variants were absent from the gnomAD database and were assumed to be damaging or probably damaging using multiple bioinformatics tools. They were both located in the C-terminal domain. The amino acid residues were highly conserved among various species. Clinically, the seizures occurred at a young age and were under control after combined treatment. Electrophysiological analysis revealed that the KCNJ3 Leu333Ser and Arg313Gln variants significantly compromised the current activities and exhibited loss-of-function (LOF) effects. CONCLUSION Our findings suggest that de novo LOF variants in KCNJ3 are associated with early-onset epilepsy. Genetic testing of KCNJ3 in patients with epilepsy may serve as a strategy for precision medicine.
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Affiliation(s)
- Juan Li
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, Hunan, China
| | - Shiyue Mei
- Henan Provincial Key Laboratory of Children's Genetics and Metabolic Diseases, Children's Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan, China
| | - Xiao Mao
- Department of Medical Genetics, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China
- National Health Commission Key Laboratory for Birth Defect Research and Prevention, Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China
| | - Lily Wan
- Department of Anatomy & Neurobiology, Central South University Xiangya School of Medicine, Changsha, Hunan, China
| | - Hua Wang
- Department of Medical Genetics, Hunan Children's Hospital, Changsha, Hunan, China
| | - Bo Xiao
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, Hunan, China
| | - Yanmin Song
- Department of Emergency Medicine, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Weiyue Gu
- Chigene (Beijing) Translational Medical Research Center Co. Ltd, Beijing, China
| | - Yan Liu
- Department of Pediatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Lili Long
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan, China
- National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Clinical Research Center for Epileptic Disease of Hunan Province, Central South University, Changsha, Hunan, China
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Oh Y, Yoo ES, Ju SH, Kim E, Lee S, Kim S, Wickman K, Sohn JW. GIRK2 potassium channels expressed by the AgRP neurons decrease adiposity and body weight in mice. PLoS Biol 2023; 21:e3002252. [PMID: 37594983 PMCID: PMC10468093 DOI: 10.1371/journal.pbio.3002252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 08/30/2023] [Accepted: 07/12/2023] [Indexed: 08/20/2023] Open
Abstract
It is well known that the neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons increase appetite and decrease thermogenesis. Previous studies demonstrated that optogenetic and/or chemogenetic manipulations of NPY/AgRP neuronal activity alter food intake and/or energy expenditure (EE). However, little is known about intrinsic molecules regulating NPY/AgRP neuronal excitability to affect long-term metabolic function. Here, we found that the G protein-gated inwardly rectifying K+ (GIRK) channels are key to stabilize NPY/AgRP neurons and that NPY/AgRP neuron-selective deletion of the GIRK2 subunit results in a persistently increased excitability of the NPY/AgRP neurons. Interestingly, increased body weight and adiposity observed in the NPY/AgRP neuron-selective GIRK2 knockout mice were due to decreased sympathetic activity and EE, while food intake remained unchanged. The conditional knockout mice also showed compromised adaptation to coldness. In summary, our study identified GIRK2 as a key determinant of NPY/AgRP neuronal excitability and driver of EE in physiological and stress conditions.
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Affiliation(s)
- Youjin Oh
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Eun-Seon Yoo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Sang Hyeon Ju
- Department of Internal Medicine, Chungnam National University Hospital, Daejeon, South Korea
| | - Eunha Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Seulgi Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Seyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jong-Woo Sohn
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
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Tsukamoto H, Kubo Y. A self-inactivating invertebrate opsin optically drives biased signaling toward Gβγ-dependent ion channel modulation. Proc Natl Acad Sci U S A 2023; 120:e2301269120. [PMID: 37186850 PMCID: PMC10214182 DOI: 10.1073/pnas.2301269120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 04/13/2023] [Indexed: 05/17/2023] Open
Abstract
Animal opsins, light-sensitive G protein-coupled receptors, have been used for optogenetic tools to control G protein-dependent signaling pathways. Upon G protein activation, the Gα and Gβγ subunits drive different intracellular signaling pathways, leading to complex cellular responses. For some purposes, Gα- and Gβγ-dependent signaling needs to be separately modulated, but these responses are simultaneously evoked due to the 1:1 stoichiometry of Gα and Gβγ Nevertheless, we show temporal activation of G protein using a self-inactivating invertebrate opsin, Platynereis c-opsin1, drives biased signaling for Gβγ-dependent GIRK channel activation in a light-dependent manner by utilizing the kinetic difference between Gβγ-dependent and Gα-dependent responses. The opsin-induced transient Gi/o activation preferentially causes activation of the kinetically fast Gβγ-dependent GIRK channels rather than slower Gi/oα-dependent adenylyl cyclase inhibition. Although similar Gβγ-biased signaling properties were observed in a self-inactivating vertebrate visual pigment, Platynereis c-opsin1 requires fewer retinal molecules to evoke cellular responses. Furthermore, the Gβγ-biased signaling properties of Platynereis c-opsin1 are enhanced by genetically fusing with RGS8 protein, which accelerates G protein inactivation. The self-inactivating invertebrate opsin and its RGS8-fusion protein can function as optical control tools biased for Gβγ-dependent ion channel modulation.
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Affiliation(s)
- Hisao Tsukamoto
- Department of Biology, Kobe University, Kobe657-8501, Japan
- Department of Life and Coordination-Complex Molecular Science, Institute for Molecular Science, Okazaki444-8585, Japan
- Japan Science and Technology Agency, Precursory Research for Embryonic Science and Technology, Kawaguchi 332-0012, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki444-8585, Japan
- Department of Physiological Sciences, The Graduate University for Advanced Studies, Hayama240-0193, Japan
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4
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Colombo S, Reddy HP, Petri S, Williams DJ, Shalomov B, Dhindsa RS, Gelfman S, Krizay D, Bera AK, Yang M, Peng Y, Makinson CD, Boland MJ, Frankel WN, Goldstein DB, Dascal N. Epilepsy in a mouse model of GNB1 encephalopathy arises from altered potassium (GIRK) channel signaling and is alleviated by a GIRK inhibitor. Front Cell Neurosci 2023; 17:1175895. [PMID: 37275776 PMCID: PMC10232839 DOI: 10.3389/fncel.2023.1175895] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 04/12/2023] [Indexed: 06/07/2023] Open
Abstract
De novo mutations in GNB1, encoding the Gβ1 subunit of G proteins, cause a neurodevelopmental disorder with global developmental delay and epilepsy, GNB1 encephalopathy. Here, we show that mice carrying a pathogenic mutation, K78R, recapitulate aspects of the disorder, including developmental delay and generalized seizures. Cultured mutant cortical neurons also display aberrant bursting activity on multi-electrode arrays. Strikingly, the antiepileptic drug ethosuximide (ETX) restores normal neuronal network behavior in vitro and suppresses spike-and-wave discharges (SWD) in vivo. ETX is a known blocker of T-type voltage-gated Ca2+ channels and G protein-coupled potassium (GIRK) channels. Accordingly, we present evidence that K78R results in a gain-of-function (GoF) effect by increasing the activation of GIRK channels in cultured neurons and a heterologous model (Xenopus oocytes)-an effect we show can be potently inhibited by ETX. This work implicates a GoF mechanism for GIRK channels in epilepsy, identifies a new mechanism of action for ETX in preventing seizures, and establishes this mouse model as a pre-clinical tool for translational research with predicative value for GNB1 encephalopathy.
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Affiliation(s)
- Sophie Colombo
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Haritha P. Reddy
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, India
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Damian J. Williams
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Boris Shalomov
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ryan S. Dhindsa
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Sahar Gelfman
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Daniel Krizay
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
| | - Amal K. Bera
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, India
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Mouse NeuroBehavior Core Facility, Columbia University Irving Medical Center, New York, NY, United States
| | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Christopher D. Makinson
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neuroscience, Columbia University, New York, NY, United States
| | - Michael J. Boland
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Neurology, Columbia University Irving Medical Center, New York, NY, United States
| | - Wayne N. Frankel
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, United States
| | - David B. Goldstein
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, United States
- Department of Genetics and Development, Columbia University Irving Medical Center, New York, NY, United States
| | - Nathan Dascal
- Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv, Israel
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5
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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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6
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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: 3] [Impact Index Per Article: 1.5] [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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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: 17] [Impact Index Per Article: 8.5] [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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Current research in pathophysiology of opioid induced respiratory depression. Curr Res Toxicol 2022; 3:100078. [PMID: 35734228 PMCID: PMC9207297 DOI: 10.1016/j.crtox.2022.100078] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/20/2022] [Accepted: 06/01/2022] [Indexed: 01/29/2023] Open
Abstract
In Oprm1-deleted KO mice, both the preBötC and the KF/PBN are major contributors to OIRD but RD is not totally eliminated. PreBötC neurons expressing NK-1R are necessary for breathing. Their deletion results in ataxic breathing and/or apnoea. GIRK channels are involved in inhibiting respiration by mu opioid receptors. KCNQ channels modulate OIRD independent of mu signaling. Morphine depresses normal but not gasping breathing in rats indicating distinct mechanisms for these 2 forms of breathing. Methadone, given to alleviate symptoms of neonatal opioid withdrawal syndrome, desensitizes rats to respiratory depression.
Respiratory depression (RD) is the primary cause of death due to opioids. Opioids bind to mu (µ)-opioid receptors (MORs) encoded by the MOR gene Oprm1, widely expressed in the central and peripheral nervous systems including centers that modulate breathing. Respiratory centers are located throughout the brainstem. Experiments with Oprm1-deleted knockout (KO) mice undertaken to determine which sites are necessary for the induction of opioid-induced respiratory depression (OIRD) showed that the pre-Bötzinger complex (preBötC) and the pontine Kölliker-Fuse nucleus (KF) contribute equally to OIRD but RD was not totally eliminated. Morphine showed a differential influence on preBötC and KF neurons – low doses attenuated RD following deletion of MORs from preBötC neurons and an increase in apneas after high doses whereas deletion of MORs from KF neurons but not the preBötC attenuated RD at both high and low doses. In other KO mice studies, morphine administration after deletion of Oprm1 from both the preBötC and the KF/PBN neurons, led to the conclusion that both respiratory centres contribute to OIRD but the preBötC predominates. MOR-mediated post-synaptic activation of GIRK potassium channels has been implicated as a cause of OIRD. A complementary mechanism in the preBötC involving KCNQ potassium channels independent of MOR signaling has been described. Recent experiments in rats showing that morphine depresses normal, but not gasping breathing, cast doubt on the belief that eupnea, sighs, and gasps, are under the control of preBötC neurons. Methadone, administered to alleviate symptoms of neonatal opioid withdrawal syndrome (NOWES), desensitized rats to OIRD. Protection lost between postnatal days 1 and 2 coincides with the preBötC becoming the dominant generator of respiratory rhythm. Neonatal antidepressant exposure syndrome (NADES) and serotonin toxicity (ST) show similarities including RD. Enzyme CYP2D6 involved in opioid detoxification is polymorphic. Individuals of different CYP2D6 genotype may show increased, decreased, or no enzyme activity, contributing to the variability of patient responses to different opioids and OIRD.
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Taylor EL, Weaver SR, Lorang IM, Arnold KM, Bradley EW, Marron Fernandez de Velasco E, Wickman K, Westendorf JJ. GIRK3 deletion facilitates kappa opioid signaling in chondrocytes, delays vascularization and promotes bone lengthening in mice. Bone 2022; 159:116391. [PMID: 35314385 PMCID: PMC9035100 DOI: 10.1016/j.bone.2022.116391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/03/2022] [Accepted: 03/14/2022] [Indexed: 11/29/2022]
Abstract
Long bones are formed and repaired through the process of endochondral ossification. Activation of G protein-coupled receptor (GPCR) signaling pathways is crucial for skeletal development and long bone growth. G protein-gated inwardly-rectifying K+ (GIRK) channel genes are key functional components and effectors of GPCR signaling pathways in excitable cells of the heart and brain, but their roles in non-excitable cells that directly contribute to endochondral bone formation have not been studied. In this study, we analyzed skeletal phenotypes of Girk2-/-, Girk3-/- and Girk2/3-/- mice. Bones from 12-week-old Girk2-/- mice were normal in length, but femurs and tibiae from Girk3-/- and Girk2/3-/- mice were longer than age-matched controls at 12-weeks-old. Epiphyseal chondrocytes from 5-day-old Girk3-/- mice expressed higher levels of genes involved in collagen chain trimerization and collagen fibril assembly, lower levels of genes encoding VEGF receptors, and produced larger micromasses than wildtype chondrocytes in vitro. Girk3-/- chondrocytes were also more responsive to the kappa opioid receptor (KOR) ligand dynorphin, as evidenced by greater pCREB expression, greater cAMP and GAG production, and upregulation of Col2a1 and Sox9 transcripts. Imaging studies showed that Kdr (Vegfr2) and endomucin expression was dramatically reduced in bones from young Girk3-/- mice, supporting a role for delayed vasculogenesis and extended postnatal endochondral bone growth. Together these data indicate that GIRK3 controls several processes involved in bone lengthening.
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Affiliation(s)
- Earnest L Taylor
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Cell Biology, University of North Carolina, NC, United States of America
| | - Samantha R Weaver
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America
| | - Ian M Lorang
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; University of Washington School of Medicine, Seattle, WA, United States of America
| | - Katherine M Arnold
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, United States of America
| | - Elizabeth W Bradley
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN, United States of America
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States of America
| | - Jennifer J Westendorf
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States of America.
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10
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Zheng F, Valero-Aracama MJ, Schaefer N, Alzheimer C. Activin A Reduces GIRK Current to Excite Dentate Gyrus Granule Cells. Front Cell Neurosci 2022; 16:920388. [PMID: 35711474 PMCID: PMC9197229 DOI: 10.3389/fncel.2022.920388] [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: 04/14/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
Activin A, a member of the TGF-β family, is recognized as a multifunctional protein in the adult brain with a particular impact on neuronal circuits associated with cognitive and affective functions. Activin receptor signaling in mouse hippocampus is strongly enhanced by the exploration of an enriched environment (EE), a behavioral paradigm known to improve performance in learning and memory tasks and to ameliorate depression-like behaviors. To interrogate the relationship between EE, activin signaling, and cellular excitability in the hippocampus, we performed ex vivo whole-cell recordings from dentate gyrus (DG) granule cells (GCs) of wild type mice and transgenic mice expressing a dominant-negative mutant of activin receptor IB (dnActRIB), which disrupts activin signaling in a forebrain-specific fashion. We found that, after overnight EE housing, GC excitability was strongly enhanced in an activin-dependent fashion. Moreover, the effect of EE on GC firing was mimicked by pre-treatment of hippocampal slices from control mice with recombinant activin A for several hours. The excitatory effect of activin A was preserved when canonical SMAD-dependent signaling was pharmacologically suppressed but was blocked by inhibitors of ERK-MAPK and PKA signaling. The involvement of a non-genomic signaling cascade was supported by the fact that the excitatory effect of activin A was already achieved within minutes of application. With respect to the ionic mechanism underlying the increase in intrinsic excitability, voltage-clamp recordings revealed that activin A induced an apparent inward current, which resulted from the suppression of a standing G protein-gated inwardly rectifying K+ (GIRK) current. The link between EE, enhanced activin signaling, and inhibition of GIRK current was strengthened by the following findings: (i) The specific GIRK channel blocker tertiapin Q (TQ) occluded the characteristic electrophysiological effects of activin A in both current- and voltage-clamp recordings. (ii) The outward current evoked by the GIRK channel activator adenosine was significantly reduced by preceding EE exploration as well as by recombinant activin A in control slices. In conclusion, our study identifies GIRK current suppression via non-canonical activin signaling as a mechanism that might at least in part contribute to the beneficial effects of EE on cognitive performance and affective behavior.
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Affiliation(s)
- Fang Zheng
- Institute of Physiology
and Pathophysiology, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Erlangen, Germany
- *Correspondence: Christian Alzheimer Fang Zheng
| | - Maria Jesus Valero-Aracama
- Institute of Physiology
and Pathophysiology, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Erlangen, Germany
| | - Natascha Schaefer
- Institute for Clinical Neurobiology, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Christian Alzheimer
- Institute of Physiology
and Pathophysiology, Friedrich-Alexander-Universität, Erlangen-Nürnberg, Erlangen, Germany
- *Correspondence: Christian Alzheimer Fang Zheng
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11
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Mechanisms of opioid-induced respiratory depression. Arch Toxicol 2022; 96:2247-2260. [PMID: 35471232 DOI: 10.1007/s00204-022-03300-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 04/06/2022] [Indexed: 11/02/2022]
Abstract
Opioid-induced respiratory depression (OIRD), the primary cause of opioid-induced death, is the neural depression of respiratory drive which, together with a decreased level of consciousness and obstructive sleep apnea, cause ventilatory insufficiency. Variability of responses to opioids and individual differences in physiological and neurological states (e.g., anesthesia, sleep-disordered breathing, concurrent drug administration) add to the risk. Multiple sites can independently exert a depressive effect on breathing, making it unclear which sites are necessary for the induction of OIRD. The generator of inspiratory rhythm is the preBötzinger complex (preBötC) in the ventrolateral medulla. Other important brainstem respiratory centres include the pontine Kölliker-Fuse and adjacent parabrachial nuclei (KF/PBN) in the dorsal lateral pons, and the dorsal respiratory group in the medulla. Deletion of μ opioid receptors from neurons showed that the preBötC and KF/PBN contribute to OIRD with the KF as a respiratory modulator and the preBötC as inspiratory rhythm generator. Glutamatergic neurons expressing NK-1R and somatostatin involved in the autonomic function of breathing, and modulatory signal pathways involving GIRK and KCNQ potassium channels, remain poorly understood. Reversal of OIRD has relied heavily on naloxone which also reverses analgesia but mismatches between the half-lives of naloxone and opioids can make it difficult to clinically safely avoid OIRD. Maternal opioid use, which is rising, increases apneas and destabilizes neonatal breathing but opioid effects on maternal and neonatal respiratory circuits in neonatal abstinence syndrome (NAS) are not well understood. Methadone, administered to alleviate symptoms of NAS in humans, desensitizes rats to RD.
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12
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Anderson EM, Demis S, Wrucke B, Engelhardt A, Hearing MC. Infralimbic cortex pyramidal neuron GIRK signaling contributes to regulation of cognitive flexibility but not affect-related behavior in male mice. Physiol Behav 2021; 242:113597. [PMID: 34536435 DOI: 10.1016/j.physbeh.2021.113597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/30/2021] [Accepted: 09/13/2021] [Indexed: 10/20/2022]
Abstract
Dysfunction of the infralimbic cortical (ILC) region of the medial prefrontal cortex (mPFC) is thought to be an underlying factor in both affect- and cognition-related behavioral deficits that co-occur across neuropsychiatric disorders. Increasing evidence highlights pathological imbalances in prefrontal pyramidal neuron excitability and associated aberrant firing as an underlying factor in this dysfunction. G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels mediate excitability of mPFC pyramidal neurons, however the functional role of these channels in ILC-dependent regulation of behavior and pyramidal neuron excitation is unknown. The present study used a viral-cre approach in male mice harboring a 'floxed' version of the kcnj3 (Girk1) gene, to disrupt GIRK1-containing channel expression in pyramidal neurons within the ILC. Loss of GIRK1-dependent signaling increased excitability and spike firing of pyramidal neurons but did not alter affective behavior measured in an elevated plus maze, forced swim test, or progressive ratio test of motivation. Alternatively, ablation of GIRK1 impaired performance in an operant-based attentional set-shifting task designed to assess cognitive flexibility. These data highlight a unique role for GIRK1 signaling in ILC pyramidal neurons in the regulation of strategy shifting but not affect and suggest that these channels may represent a therapeutic target for treatment of cognitive deficits in neuropsychiatric disease.
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13
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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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Bony AR, McArthur JR, Finol-Urdaneta RK, Adams DJ. Analgesic α-conotoxins modulate native and recombinant GIRK1/2 channels via activation of GABA B receptors and reduce neuroexcitability. Br J Pharmacol 2021; 179:179-198. [PMID: 34599513 DOI: 10.1111/bph.15690] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 08/25/2021] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE Activation of GIRK channels via G protein-coupled GABAB receptors has been shown to attenuate nociceptive transmission. The analgesic α-conotoxin Vc1.1 activates GABAB receptors resulting in inhibition of Cav 2.2 and Cav 2.3 channels in mammalian primary afferent neurons. Here, we investigated the effects of analgesic α-conotoxins on recombinant and native GIRK-mediated K+ currents and on neuronal excitability. EXPERIMENTAL APPROACH The effects of analgesic α-conotoxins, Vc1.1, RgIA, and PeIA, were investigated on inwardly-rectifying K+ currents in HEK293T cells recombinantly co-expressing either heteromeric human GIRK1/2 or homomeric GIRK2 subunits, with GABAB receptors. The effects of α-conotoxin Vc1.1 and baclofen were studied on GIRK-mediated K+ currents and the passive and active electrical properties of adult mouse dorsal root ganglion neurons. KEY RESULTS Analgesic α-conotoxins Vc1.1, RgIA, and PeIA potentiate inwardly-rectifying K+ currents in HEK293T cells recombinantly expressing human GIRK1/2 channels and GABAB receptors. GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen occurs via a pertussis toxin-sensitive G protein and is inhibited by the selective GABAB receptor antagonist CGP 55845. In adult mouse dorsal root ganglion neurons, GABAB receptor-dependent GIRK channel potentiation by Vc1.1 and baclofen hyperpolarizes the cell membrane potential and reduces excitability. CONCLUSIONS AND IMPLICATIONS This is the first report of GIRK channel potentiation via allosteric α-conotoxin Vc1.1-GABAB receptor agonism, leading to decreased neuronal excitability. Such action potentially contributes to the analgesic effects of Vc1.1 and baclofen observed in vivo.
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Affiliation(s)
- Anuja R Bony
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Jeffrey R McArthur
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - Rocio K Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
| | - David J Adams
- Illawarra Health and Medical Research Institute (IHMRI), University of Wollongong, Wollongong, NSW, Australia
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Encephalopathy-causing mutations in Gβ 1 ( GNB1) alter regulation of neuronal GIRK channels. iScience 2021; 24:103018. [PMID: 34522861 PMCID: PMC8426278 DOI: 10.1016/j.isci.2021.103018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 08/04/2021] [Accepted: 08/18/2021] [Indexed: 11/24/2022] Open
Abstract
Mutations in the GNB1 gene, encoding the Gβ1 subunit of heterotrimeric G proteins, cause GNB1 Encephalopathy. Patients experience seizures, pointing to abnormal activity of ion channels or neurotransmitter receptors. We studied three Gβ1 mutations (K78R, I80N and I80T) using computational and functional approaches. In heterologous expression models, these mutations did not alter the coupling between G protein-coupled receptors to Gi/o, or the Gβγ regulation of the neuronal voltage-gated Ca2+ channel CaV2.2. However, the mutations profoundly affected the Gβγ regulation of the G protein-gated inwardly rectifying potassium channels (GIRK, or Kir3). Changes were observed in Gβ1 protein expression levels, Gβγ binding to cytosolic segments of GIRK subunits, and in Gβγ function, and included gain-of-function for K78R or loss-of-function for I80T/N, which were GIRK subunit-specific. Our findings offer new insights into subunit-dependent gating of GIRKs by Gβγ, and indicate diverse etiology of GNB1 Encephalopathy cases, bearing a potential for personalized treatment. GIRK channels are key players affected by GNB1 mutations under study (K78R and I80N/T) Effects of mutations (LoF or GoF) are channel subunit composition-specific The findings help to understand the GNB1 encephalopathy and to devise treatments The results yield new insights into mechanisms of Gβγ regulation of GIRKs
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16
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Anderson A, Vo BN, de Velasco EMF, Hopkins CR, Weaver CD, Wickman K. Characterization of VU0468554, a New Selective Inhibitor of Cardiac G Protein-Gated Inwardly Rectifying K + Channels. Mol Pharmacol 2021; 100:540-547. [PMID: 34503975 DOI: 10.1124/molpharm.121.000311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/01/2021] [Indexed: 11/22/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are critical mediators of excitability in the heart and brain. Enhanced GIRK-channel activity has been implicated in the pathogenesis of supraventricular arrhythmias, including atrial fibrillation. The lack of selective pharmacological tools has impeded efforts to investigate the therapeutic potential of cardiac GIRK-channel interventions in arrhythmias. Here, we characterize a recently identified GIRK-channel inhibitor, VU0468554. Using whole-cell electrophysiological approaches and primary cultures of sinoatrial nodal cells and hippocampal neurons, we show that VU0468554 more effectively inhibits the cardiac GIRK channel than the neuronal GIRK channel. Concentration-response experiments suggest that VU0468554 inhibits Gβγ-activated GIRK channels in noncompetitive and potentially uncompetitive fashion. In contrast, VU0468554 competitively inhibits GIRK-channel activation by ML297, a GIRK-channel activator containing the same chemical scaffold as VU0468554. In the isolated heart model, VU0468554 partially reversed carbachol-induced bradycardia in hearts from wild-type mice but not Girk4-/- mice. Collectively, these data suggest that VU0468554 represents a promising new pharmacological tool for targeting cardiac GIRK channels with therapeutic implications for relevant cardiac arrhythmias. SIGNIFICANCE STATEMENT: Although cardiac GIRK-channel inhibition shows promise for the treatment of supraventricular arrhythmias, the absence of subtype-selective channel inhibitors has hindered exploration into this therapeutic strategy. This study utilizes whole-cell patch-clamp electrophysiology to characterize the new GIRK-channel inhibitor VU0468554 in human embryonic kidney 293T cells and primary cultures. We report that VU0468554 exhibits a favorable pharmacodynamic profile for cardiac over neuronal GIRK channels and partially reverses GIRK-mediated bradycardia in the isolated mouse heart model.
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Affiliation(s)
- Allison Anderson
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Baovi N Vo
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Ezequiel Marron Fernandez de Velasco
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Corey R Hopkins
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - C David Weaver
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Kevin Wickman
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
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Lippiello P, Hoxha E, Tempia F, Miniaci MC. GIRK1-Mediated Inwardly Rectifying Potassium Current Is a Candidate Mechanism Behind Purkinje Cell Excitability, Plasticity, and Neuromodulation. THE CEREBELLUM 2021; 19:751-761. [PMID: 32617840 DOI: 10.1007/s12311-020-01158-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
G-protein-coupled inwardly rectifying potassium (GIRK) channels contribute to the resting membrane potential of many neurons and play an important role in controlling neuronal excitability. Although previous studies have revealed a high expression of GIRK subunits in the cerebellum, their functional role has never been clearly described. Using patch-clamp recordings in mice cerebellar slices, we examined the properties of the GIRK currents in Purkinje cells (PCs) and investigated the effects of a selective agonist of GIRK1-containing channels, ML297 (ML), on PC firing and synaptic plasticity. We demonstrated that GIRK channel activation decreases the PC excitability by inhibiting both sodium and calcium spikes and, in addition, modulates the complex spike response evoked by climbing fiber stimulation. Our results indicate that GIRK channels have also a marked effect on synaptic plasticity of the parallel fiber-PC synapse, as the application of ML297 increased the expression of LTP while preventing LTD. We, therefore, propose that the recruitment of GIRK channels represents a crucial mechanism by which neuromodulators can control synaptic strength and membrane conductance for proper refinement of the neural network involved in memory storage and higher cognitive functions.
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Affiliation(s)
- Pellegrino Lippiello
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy
| | - Eriola Hoxha
- Department of Neuroscience, University of Turin, Turin, Italy.,Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy
| | - Filippo Tempia
- Department of Neuroscience, University of Turin, Turin, Italy. .,Neuroscience Institute Cavalieri Ottolenghi (NICO), Turin, Italy. .,National Institute of Neuroscience (INN), Turin, Italy.
| | - Maria Concetta Miniaci
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Naples, Italy.
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18
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Djebari S, Iborra-Lázaro G, Temprano-Carazo S, Sánchez-Rodríguez I, Nava-Mesa MO, Múnera A, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. G-Protein-Gated Inwardly Rectifying Potassium (Kir3/GIRK) Channels Govern Synaptic Plasticity That Supports Hippocampal-Dependent Cognitive Functions in Male Mice. J Neurosci 2021; 41:7086-7102. [PMID: 34261700 PMCID: PMC8372024 DOI: 10.1523/jneurosci.2849-20.2021] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 01/17/2023] Open
Abstract
The G-protein-gated inwardly rectifying potassium (Kir3/GIRK) channel is the effector of many G-protein-coupled receptors (GPCRs). Its dysfunction has been linked to the pathophysiology of Down syndrome, Alzheimer's and Parkinson's diseases, psychiatric disorders, epilepsy, drug addiction, or alcoholism. In the hippocampus, GIRK channels decrease excitability of the cells and contribute to resting membrane potential and inhibitory neurotransmission. Here, to elucidate the role of GIRK channels activity in the maintenance of hippocampal-dependent cognitive functions, their involvement in controlling neuronal excitability at different levels of complexity was examined in C57BL/6 male mice. For that purpose, GIRK activity in the dorsal hippocampus CA3-CA1 synapse was pharmacologically modulated by two drugs: ML297, a GIRK channel opener, and Tertiapin-Q (TQ), a GIRK channel blocker. Ex vivo, using dorsal hippocampal slices, we studied the effect of pharmacological GIRK modulation on synaptic plasticity processes induced in CA1 by Schaffer collateral stimulation. In vivo, we performed acute intracerebroventricular (i.c.v.) injections of the two GIRK modulators to study their contribution to electrophysiological properties and synaptic plasticity of dorsal hippocampal CA3-CA1 synapse, and to learning and memory capabilities during hippocampal-dependent tasks. We found that pharmacological disruption of GIRK channel activity by i.c.v. injections, causing either function gain or function loss, induced learning and memory deficits by a mechanism involving neural excitability impairments and alterations in the induction and maintenance of long-term synaptic plasticity processes. These results support the contention that an accurate control of GIRK activity must take place in the hippocampus to sustain cognitive functions.SIGNIFICANCE STATEMENT Cognitive processes of learning and memory that rely on hippocampal synaptic plasticity processes are critically ruled by a finely tuned neural excitability. G-protein-gated inwardly rectifying K+ (GIRK) channels play a key role in maintaining resting membrane potential, cell excitability and inhibitory neurotransmission. Here, we demonstrate that modulation of GIRK channels activity, causing either function gain or function loss, transforms high-frequency stimulation (HFS)-induced long-term potentiation (LTP) into long-term depression (LTD), inducing deficits in hippocampal-dependent learning and memory. Together, our data show a crucial GIRK-activity-mediated mechanism that governs synaptic plasticity direction and modulates subsequent hippocampal-dependent cognitive functions.
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Affiliation(s)
- Souhail Djebari
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Guillermo Iborra-Lázaro
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Sara Temprano-Carazo
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Irene Sánchez-Rodríguez
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Mauricio O Nava-Mesa
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
- Neuroscience Research Group (NEUROS), Universidad del Rosario, Bogotá, Colombia 111711
| | - Alejandro Múnera
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
- Behavioral Neurophysiology Laboratory, Universidad Nacional de Colombia, Bogotá, Colombia 111321
| | - Agnès Gruart
- Division of Neurosciences, Pablo de Olavide University, Seville, Spain 41013
| | | | - Lydia Jiménez-Díaz
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
| | - Juan D Navarro-López
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Spain 13071
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19
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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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20
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Vo BN, Marron Fernandez de Velasco E, Rose TR, Oberle H, Luo H, Hopkins CR, Wickman K. Bidirectional Influence of Limbic GIRK Channel Activation on Innate Avoidance Behavior. J Neurosci 2021; 41:5809-5821. [PMID: 34039657 PMCID: PMC8265807 DOI: 10.1523/jneurosci.2787-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 05/14/2021] [Accepted: 05/19/2021] [Indexed: 11/21/2022] Open
Abstract
Systemic administration of ML297, a selective activator of G-protein-gated inwardly rectifying K+ (GIRK) channels, decreases innate avoidance behavior in male C57BL/6J mice. The cellular mechanisms mediating the ML297-induced suppression of avoidance behavior are unknown. Here, we show that systemic ML297 administration suppresses elevated plus maze (EPM)-induced neuronal activation in the ventral hippocampus (vHPC) and basolateral amygdala (BLA) and that ML297 activates GIRK1-containing GIRK channels in these limbic structures. While intracranial infusion of ML297 into the vHPC suppressed avoidance behavior in the EPM test, mirroring the effect of systemic ML297, intra-BLA administration of ML297 provoked the opposite effect. Using neuron-specific viral genetic and chemogenetic approaches, we found that the combined inhibition of excitatory neurons in CA3 and dentate gyrus (DG) subregions of the vHPC was sufficient to decrease innate avoidance behavior in the EPM, open-field, and light-dark tests in male C57BL/6J mice, while performance in the marble-burying test was not impacted. Furthermore, genetic ablation of GIRK channels in CA3/DG excitatory neurons precluded the suppression of avoidance behavior evoked by systemic ML297 in the EPM test. Thus, acute inhibition of excitatory neurons in the ventral CA3 and DG subregions of the vHPC is necessary for the apparent anxiolytic efficacy of systemic ML297 and is sufficient to decrease innate avoidance behavior in male C57BL/6J mice.SIGNIFICANCE STATEMENT We interrogated the cellular mechanisms underlying the apparent anxiolytic efficacy of ML297, a selective activator of G-protein-gated inwardly rectifying K+ (GIRK) channels and promising lead compound. Intracranial infusion of ML297 into the ventral hippocampus (vHPC) and basolateral amygdala (BLA) complex exerted opposing influence on innate avoidance behavior in male C57BL/6J mice, the former recapitulating the suppression of avoidance behavior evoked by systemic ML297. Using viral genetic and chemogenetic approaches, we showed that combined inhibition of excitatory neurons in CA3 and dentate gyrus (DG) subregions of the vHPC is sufficient to decrease innate avoidance behavior in male mice and mediates the decrease in avoidance behavior evoked by systemic ML297. These findings establish a foundation for future investigations into the therapeutic potential of GIRK channel modulation in anxiety disorders.
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Affiliation(s)
- Baovi N Vo
- Graduate Program in Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | | | - Timothy R Rose
- Graduate Program in Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Hannah Oberle
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Haichang Luo
- Graduate Program in Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Corey R Hopkins
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455
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21
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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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22
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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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23
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Mett A, Karbat I, Tsoory M, Fine S, Iwanir S, Reuveny E. Reduced activity of GIRK1-containing heterotetramers is sufficient to affect neuronal functions, including synaptic plasticity and spatial learning and memory. J Physiol 2020; 599:521-545. [PMID: 33124684 DOI: 10.1113/jp280434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/27/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS G-protein inwardly rectifying K+ (GIRK) channels consist of four homologous subunits (GIRK1-4) and are essential regulators of electrical excitability in the nervous system. GIRK2-null mice have been widely investigated for their distinct behaviour and altered depotentiation following long-term potentiation (LTP), whereas GIRK1 mice are less well characterized. Here we utilize a novel knockin mouse strain in which the GIRK1 subunit is fluorescently tagged with yellow fluorescent protein (YFP-GIRK1) and the GIRK1-null mouse line to investigate the role of GIRK1 in neuronal processes such as spatial learning and memory, locomotion and depotentiation following LTP. Neurons dissected from YFP-GIRK1 mice had significantly reduced potassium currents and this mouse line phenotypically resembled GIRK1-null mice, making it a 'functional knockdown' model of GIRK1-containing channels. YFP-GIRK1 and GIRK1-null mice had increased locomotion, reduced spatial learning and memory and blunted depotentiation following LTP. ABSTRACT GIRK channels are essential for the slow inhibition of electrical activity in the nervous system and heart rate regulation via the parasympathetic system. The implications of individual GIRK isoforms in specific physiological activities are based primarily on studies conducted with GIRK-null mouse lines. Here we utilize a novel knockin mouse line in which YFP was fused in-frame to the N-terminus of GIRK1 (YFP-GIRK1) to correlate GIRK1 spatial distribution with physiological activities. These mice, however, displayed spontaneous seizure-like activity and thus were investigated for the origin of such activity. We show that GIRK tetramers containing YFP-GIRK1 are correctly assembled and trafficked to the plasma membrane, but are functionally impaired. A battery of behavioural assays conducted on YFP-GIRK1 and GIRK1-null (GIRK1-/- ) mice revealed similar phenotypes, including impaired nociception, reduced anxiety and hyperactivity in an unfamiliar environment. However, YFP-GIRK1 mice exhibited increased home-cage locomotion while GIRK1-/- mice did not. In addition, we show that the GIRK1 subunit is essential for intact spatial learning and memory and synaptic plasticity in hippocampal brain slices. This study expands our knowledge regarding the role of GIRK1 in neuronal processes and underlines the importance of GIRK1-containing heterotetramers.
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Affiliation(s)
- Alice Mett
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Izhar Karbat
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Michael Tsoory
- Department of Veterinary Resources, Weizmann Institute of Science, Rehovot, Israel
| | - Shachar Fine
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Shachar Iwanir
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Eitan Reuveny
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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24
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Pfeil EM, Brands J, Merten N, Vögtle T, Vescovo M, Rick U, Albrecht IM, Heycke N, Kawakami K, Ono Y, Ngako Kadji FM, Hiratsuka S, Aoki J, Häberlein F, Matthey M, Garg J, Hennen S, Jobin ML, Seier K, Calebiro D, Pfeifer A, Heinemann A, Wenzel D, König GM, Nieswandt B, Fleischmann BK, Inoue A, Simon K, Kostenis E. Heterotrimeric G Protein Subunit Gαq Is a Master Switch for Gβγ-Mediated Calcium Mobilization by Gi-Coupled GPCRs. Mol Cell 2020; 80:940-954.e6. [PMID: 33202251 DOI: 10.1016/j.molcel.2020.10.027] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 09/21/2020] [Accepted: 10/16/2020] [Indexed: 12/18/2022]
Abstract
Mechanisms that control mobilization of cytosolic calcium [Ca2+]i are key for regulation of numerous eukaryotic cell functions. One such paradigmatic mechanism involves activation of phospholipase Cβ (PLCβ) enzymes by G protein βγ subunits from activated Gαi-Gβγ heterotrimers. Here, we report identification of a master switch to enable this control for PLCβ enzymes in living cells. We find that the Gαi-Gβγ-PLCβ-Ca2+ signaling module is entirely dependent on the presence of active Gαq. If Gαq is pharmacologically inhibited or genetically ablated, Gβγ can bind to PLCβ but does not elicit Ca2+ signals. Removal of an auto-inhibitory linker that occludes the active site of the enzyme is required and sufficient to empower "stand-alone control" of PLCβ by Gβγ. This dependence of Gi-Gβγ-Ca2+ on Gαq places an entire signaling branch of G-protein-coupled receptors (GPCRs) under hierarchical control of Gq and changes our understanding of how Gi-GPCRs trigger [Ca2+]i via PLCβ enzymes.
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Affiliation(s)
- Eva Marie Pfeil
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Julian Brands
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Nicole Merten
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Timo Vögtle
- Institute of Experimental Biomedicine I, University Hospital Würzburg and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Maddalena Vescovo
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Ulrike Rick
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Ina-Maria Albrecht
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Nina Heycke
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Kouki Kawakami
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Yuki Ono
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | | | - Suzune Hiratsuka
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Junken Aoki
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Felix Häberlein
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany; Research Training Group 1873, University of Bonn, Bonn, Germany
| | - Michaela Matthey
- Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, 44801 Bochum, Germany; Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Jaspal Garg
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, 53127 Bonn, Germany
| | - Stephanie Hennen
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany
| | - Kerstin Seier
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, 97078 Würzburg, Germany; Institute of Metabolism and Systems Research and Centre of Membrane Proteins and Receptors, University of Birmingham, B15 2TT Birmingham, UK
| | - Alexander Pfeifer
- Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Akos Heinemann
- Division of Pharmacology, Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Medical University of Graz, 8010 Graz, Austria
| | - Daniela Wenzel
- Department of Systems Physiology, Medical Faculty, Ruhr University Bochum, 44801 Bochum, Germany; Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Gabriele M König
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital Würzburg and Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Bernd K Fleischmann
- Institute of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
| | - Asuka Inoue
- Graduate School of Pharmaceutical Science, Tohoku University, Sendai 980-8578, Japan
| | - Katharina Simon
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
| | - Evi Kostenis
- Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
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25
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Mechanisms and Regulation of Neuronal GABA B Receptor-Dependent Signaling. Curr Top Behav Neurosci 2020; 52:39-79. [PMID: 32808092 DOI: 10.1007/7854_2020_129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
γ-Aminobutyric acid B receptors (GABABRs) are broadly expressed throughout the central nervous system where they play an important role in regulating neuronal excitability and synaptic transmission. GABABRs are G protein-coupled receptors that mediate slow and sustained inhibitory actions via modulation of several downstream effector enzymes and ion channels. GABABRs are obligate heterodimers that associate with diverse arrays of proteins to form modular complexes that carry out distinct physiological functions. GABABR-dependent signaling is fine-tuned and regulated through a multitude of mechanisms that are relevant to physiological and pathophysiological states. This review summarizes the current knowledge on GABABR signal transduction and discusses key factors that influence the strength and sensitivity of GABABR-dependent signaling in neurons.
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26
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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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27
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Walsh KB. Screening Technologies for Inward Rectifier Potassium Channels: Discovery of New Blockers and Activators. SLAS DISCOVERY 2020; 25:420-433. [PMID: 32292089 DOI: 10.1177/2472555220905558] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
K+ channels play a critical role in maintaining the normal electrical activity of excitable cells by setting the cell resting membrane potential and by determining the shape and duration of the action potential. In nonexcitable cells, K+ channels establish electrochemical gradients necessary for maintaining salt and volume homeostasis of body fluids. Inward rectifier K+ (Kir) channels typically conduct larger inward currents than outward currents, resulting in an inwardly rectifying current versus voltage relationship. This property of inward rectification results from the voltage-dependent block of the channels by intracellular polyvalent cations and makes these channels uniquely designed for maintaining the resting potential near the K+ equilibrium potential (EK). The Kir family of channels consist of seven subfamilies of channels (Kir1.x through Kir7.x) that include the classic inward rectifier (Kir2.x) channel, the G-protein-gated inward rectifier K+ (GIRK) (Kir3.x), and the adenosine triphosphate (ATP)-sensitive (KATP) (Kir 6.x) channels as well as the renal Kir1.1 (ROMK), Kir4.1, and Kir7.1 channels. These channels not only function to regulate electrical/electrolyte transport activity, but also serve as effector molecules for G-protein-coupled receptors (GPCRs) and as molecular sensors for cell metabolism. Of significance, Kir channels represent promising pharmacological targets for treating a number of clinical conditions, including cardiac arrhythmias, anxiety, chronic pain, and hypertension. This review provides a brief background on the structure, function, and pharmacology of Kir channels and then focuses on describing and evaluating current high-throughput screening (HTS) technologies, such as membrane potential-sensitive fluorescent dye assays, ion flux measurements, and automated patch clamp systems used for Kir channel drug discovery.
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Affiliation(s)
- Kenneth B Walsh
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC, USA
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28
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Lyu C, Lyu GW, Mulder J, Martinez A, Shi TJS. G Protein-Gated Inwardly Rectifying Potassium Channel Subunit 3 is Upregulated in Rat DRGs and Spinal Cord After Peripheral Nerve Injury. J Pain Res 2020; 13:419-429. [PMID: 32110090 PMCID: PMC7034995 DOI: 10.2147/jpr.s233744] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/28/2020] [Indexed: 12/15/2022] Open
Abstract
Background G protein-gated inwardly rectifying potassium (GIRK) channels are involved in the regulation of neuronal excitability. Four GIRK subunits (GIRK1-4) are expressed in rat dorsal root ganglia (DRGs). Recently, we have characterized the expression of GIRK1 and −2, and both are downregulated in rat DRGs and spinal cord after a complete sciatic nerve transection (axotomy). Here, we aimed to study the neurochemical characteristics of GIRK3, and its regulation in rat DRGs and spinal cord induced by nerve injury. Methods A sciatic nerve axotomy was performed to study the influences of injury on GIRK3 expression in DRGs and spinal cord. A dorsal root rhizotomy and a sciatic nerve crush were employed to study the axonal transport of GIRK3 protein, respectively. Immunohistochemistry analysis was employed for investigating the neurochemical characteristics of GIRK3. Results In control DRGs, ~18% of neuron profiles (NPs) were GIRK3-positive (+), and ~41%, ~48% and ~45% of GIRK3+ NPs were CGRP+, IB4+ and NF200+, respectively. GIRK3-like immunoreactivity was observed in glabrous skin of hind paws and axons originating from DRG neurons. Fourteen days after axotomy, more than one-third of DRG NPs were GIRK3+, and among these ~51% and ~56% coexpressed galanin and neuropeptide Y, respectively. In control animals, a small group of interneurons found in the dorsal horn was GIRK3+. In addition, GIRK3+ processes could be observed in superficial laminae of spinal dorsal horn. After nerve injury, the intensity of GIRK3-like immunoreactivity in the superficial layers was increased. Evidence based on rhizotomy and sciatic nerve crush indicated both anterograde and retrograde transport of GIRK3. Conclusion Our study demonstrates that GIRK3 is expressed in sensory neurons and spinal cord. GIRK3 has both anterograde and retrograde axonal transport. GIRK3 expression can be regulated by peripheral nerve injury.
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Affiliation(s)
- Chuang Lyu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, Harbin 150069, People's Republic of China
| | - Gong-Wei Lyu
- Department of Neurology, 1st Hospital of Harbin Medical University, Harbin 150001, People's Republic of China
| | - Jan Mulder
- Department of Neuroscience, Karolinska Institutet, Stockholm SE-171 77, Sweden.,Science for Life Laboratory, Karolinska Institutet, Stockholm SE-171 65, Sweden
| | - Aurora Martinez
- Department of Biomedicine, University of Bergen, Bergen 5009, Norway
| | - Tie-Jun Sten Shi
- Department of Biomedicine, University of Bergen, Bergen 5009, Norway
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29
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Sánchez-Rodríguez I, Djebari S, Temprano-Carazo S, Vega-Avelaira D, Jiménez-Herrera R, Iborra-Lázaro G, Yajeya J, Jiménez-Díaz L, Navarro-López JD. Hippocampal long-term synaptic depression and memory deficits induced in early amyloidopathy are prevented by enhancing G-protein-gated inwardly rectifying potassium channel activity. J Neurochem 2020; 153:362-376. [PMID: 31875959 PMCID: PMC7217154 DOI: 10.1111/jnc.14946] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 12/06/2019] [Accepted: 12/20/2019] [Indexed: 12/11/2022]
Abstract
Hippocampal synaptic plasticity disruption by amyloid‐β (Aβ) peptides + thought to be responsible for learning and memory impairments in Alzheimer's disease (AD) early stage. Failures in neuronal excitability maintenance seems to be an underlying mechanism. G‐protein‐gated inwardly rectifying potassium (GirK) channels control neural excitability by hyperpolarization in response to many G‐protein‐coupled receptors activation. Here, in early in vitro and in vivo amyloidosis mouse models, we study whether GirK channels take part of the hippocampal synaptic plasticity impairments generated by Aβ1–42. In vitro electrophysiological recordings from slices showed that Aβ1–42 alters synaptic plasticity by switching high‐frequency stimulation (HFS) induced long‐term potentiation (LTP) to long‐term depression (LTD), which led to in vivo hippocampal‐dependent memory deficits. Remarkably, selective pharmacological activation of GirK channels with ML297 rescued both HFS‐induced LTP and habituation memory from Aβ1–42 action. Moreover, when GirK channels were specifically blocked by Tertiapin‐Q, their activation with ML297 failed to rescue LTP from the HFS‐dependent LTD induced by Aβ1–42. On the other hand, the molecular analysis of the recorded slices by western blot showed that the expression of GIRK1/2 subunits, which form the prototypical GirK channel in the hippocampus, was not significantly regulated by Aβ1–42. However, immunohistochemical examination of our in vivo amyloidosis model showed Aβ1–42 to down‐regulate hippocampal GIRK1 subunit expression. Together, our results describe an Aβ‐mediated deleterious synaptic mechanism that modifies the induction threshold for hippocampal LTP/LTD and underlies memory alterations observed in amyloidosis models. In this scenario, GirK activation assures memory formation by preventing the transformation of HFS‐induced LTP into LTD. ![]()
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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, Ciudad Real, Spain
| | - Souhail Djebari
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Sara Temprano-Carazo
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - David Vega-Avelaira
- Departamento de Ciencias Biomédicas Básicas, European University of Madrid, Madrid, Spain
| | - Raquel Jiménez-Herrera
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Guillermo Iborra-Lázaro
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, Ciudad Real, Spain
| | - Javier Yajeya
- Instituto de Neurociencias de Castilla y León, University of Salamanca, Salamanca, Spain
| | - Lydia Jiménez-Díaz
- NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, University of Castilla-La Mancha, 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, Ciudad Real, Spain
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30
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Xu Y, Cantwell L, Molosh AI, Plant LD, Gazgalis D, Fitz SD, Dustrude ET, Yang Y, Kawano T, Garai S, Noujaim SF, Shekhar A, Logothetis DE, Thakur GA. The small molecule GAT1508 activates brain-specific GIRK1/2 channel heteromers and facilitates conditioned fear extinction in rodents. J Biol Chem 2020; 295:3614-3634. [PMID: 31953327 DOI: 10.1074/jbc.ra119.011527] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/09/2020] [Indexed: 01/31/2023] Open
Abstract
G-protein-gated inwardly-rectifying K+ (GIRK) channels are targets of Gi/o-protein-signaling systems that inhibit cell excitability. GIRK channels exist as homotetramers (GIRK2 and GIRK4) or heterotetramers with nonfunctional homomeric subunits (GIRK1 and GIRK3). Although they have been implicated in multiple conditions, the lack of selective GIRK drugs that discriminate among the different GIRK channel subtypes has hampered investigations into their precise physiological relevance and therapeutic potential. Here, we report on a highly-specific, potent, and efficacious activator of brain GIRK1/2 channels. Using a chemical screen and electrophysiological assays, we found that this activator, the bromothiophene-substituted small molecule GAT1508, is specific for brain-expressed GIRK1/2 channels rather than for cardiac GIRK1/4 channels. Computational models predicted a GAT1508-binding site validated by experimental mutagenesis experiments, providing insights into how urea-based compounds engage distant GIRK1 residues required for channel activation. Furthermore, we provide computational and experimental evidence that GAT1508 is an allosteric modulator of channel-phosphatidylinositol 4,5-bisphosphate interactions. Through brain-slice electrophysiology, we show that subthreshold GAT1508 concentrations directly stimulate GIRK currents in the basolateral amygdala (BLA) and potentiate baclofen-induced currents. Of note, GAT1508 effectively extinguished conditioned fear in rodents and lacked cardiac and behavioral side effects, suggesting its potential for use in pharmacotherapy for post-traumatic stress disorder. In summary, our findings indicate that the small molecule GAT1508 has high specificity for brain GIRK1/2 channel subunits, directly or allosterically activates GIRK1/2 channels in the BLA, and facilitates fear extinction in a rodent model.
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Affiliation(s)
- Yu Xu
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Lucas Cantwell
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Andrei I Molosh
- Department of Psychiatry, Paul and Carole Stark Neurosciences Research Institute, Indiana Clinical and Translational Sciences Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Leigh D Plant
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Stephanie D Fitz
- Department of Psychiatry, Paul and Carole Stark Neurosciences Research Institute, Indiana Clinical and Translational Sciences Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Erik T Dustrude
- Department of Psychiatry, Paul and Carole Stark Neurosciences Research Institute, Indiana Clinical and Translational Sciences Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Yuchen Yang
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Takeharu Kawano
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Sumanta Garai
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115
| | - Sami F Noujaim
- Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida 33612
| | - Anantha Shekhar
- Department of Psychiatry, Paul and Carole Stark Neurosciences Research Institute, Indiana Clinical and Translational Sciences Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202.
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115.
| | - Ganesh A Thakur
- Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, and Center for Drug Discovery, Northeastern University, Boston, Massachusetts 02115.
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Yan R, Chen R, Wang J, Shi J, dos Santos WF, Xu Z, Liu L. Jingshu Keli and its Components Notoginsenoside R1 and Ginsenoside Rb1 Alleviate the Symptoms of Cervical Myelopathy through Kir3.1 Mediated Mechanisms. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2019; 18:631-642. [DOI: 10.2174/0929866526666190911150514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/20/2018] [Accepted: 05/06/2019] [Indexed: 12/16/2022]
Abstract
Background & Objective::
Cervical Spondylotic Myelopathy (CSM) is one of the most serious
spinal cord disorders in adults. Pharmacological modulation of ion channels is a common strategy
to interfere with CSM and prevent neuronal damage.
Methods:
Here, we investigated the effects of Jingshu Keli (JSKL), a traditional Chinese herbal formula,
on CSM-related gait abnormality, mechanical allodynia and thermal hyperalgesia, and assessed
the neuronal mechanisms of JSKL on cultured brainstem cells. Behavioral tests and patch clamp recordings
were performed to make this assessment.
Results:
In our study, we found that JSKL significantly recovered the gait performance (P<0.001) and
decreased the levels of mechanical pain in 18.9% (P<0.01) and thermal pain in 18.1% (P<0.05). Further
investigation suggested that JSKL and its containing ginsenoside Rb1 (GRb1), notoginsenoside
R1 (NGR1) reduced the action potential frequency in 38.5%, 27.2%, 25.9%, and hyperpolarized resting
membrane potential in 15.0%, 13.8%, 12.1%, respectively. Kir channels, not KV channels and KCa
channels, were the major intermediate factors achieving treatment effects. Finally, immunostaining results
showed that the phosphorylation of Kir3.1 was promoted, whereas the total expression level did
not change.
Conclusion:
Our study reveals a novel strategy of treating CSM by using Traditional Chinese Medicines
(TCMs) containing active components.
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Affiliation(s)
- Renjie Yan
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Jingan District, Shanghai, China; State Institute of Pharmaceutical Industry, Shanghai 200437, China
| | - Rui Chen
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Jingan District, Shanghai, China; State Institute of Pharmaceutical Industry, Shanghai 200437, China
| | - Jiahui Wang
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Jingan District, Shanghai, China; State Institute of Pharmaceutical Industry, Shanghai 200437, China
| | - Jian Shi
- Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Wagner Ferreira dos Santos
- Laboratory of Neurobiology and Venoms, Department of Biology, FFCLRP, University of Sao Paulo, Sao Paulo, Brazil
| | - Zhiru Xu
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Jingan District, Shanghai, China; State Institute of Pharmaceutical Industry, Shanghai 200437, China
| | - Li Liu
- State Key Laboratory of New Drug and Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, Jingan District, Shanghai, China; State Institute of Pharmaceutical Industry, Shanghai 200437, China
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32
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Long VP, Bonilla IM, Baine S, Glynn P, Kumar S, Schober K, Mowrey K, Weiss R, Lee NY, Mohler PJ, Györke S, Hund TJ, Fedorov VV, Carnes CA. Chronic heart failure increases negative chronotropic effects of adenosine in canine sinoatrial cells via A1R stimulation and GIRK-mediated I Kado. Life Sci 2019; 240:117068. [PMID: 31751583 DOI: 10.1016/j.lfs.2019.117068] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/07/2019] [Accepted: 11/14/2019] [Indexed: 12/12/2022]
Abstract
AIMS Bradycardia contributes to tachy-brady arrhythmias or sinus arrest during heart failure (HF). Sinoatrial node (SAN) adenosine A1 receptors (ADO A1Rs) are upregulated in HF, and adenosine is known to exert negative chronotropic effects on the SAN. Here, we investigated the role of A1R signaling at physiologically relevant ADO concentrations on HF SAN pacemaker cells. MAIN METHODS Dogs with tachypacing-induced chronic HF and normal controls (CTL) were studied. SAN tissue was collected for A1R and GIRK mRNA quantification. SAN cells were isolated for perforated patch clamp recordings and firing rate (bpm), slope of slow diastolic depolarization (SDD), and maximum diastolic potential (MDP) were measured. Action potentials (APs) and currents were recorded before and after addition of 1 and 10 μM ADO. To assess contributions of A1R and G protein-coupled Inward Rectifier Potassium Current (GIRK) to ADO effects, APs were measured after the addition of DPCPX (selective A1R antagonist) or TPQ (selective GIRK blocker). KEY FINDINGS A1R and GIRK mRNA expression were significantly increased in HF. In addition, ADO induced greater rate slowing and membrane hyperpolarization in HF vs CTL (p < 0.05). DPCPX prevented ADO-induced rate slowing in CTL and HF cells. The ADO-induced inward rectifying current, IKado, was observed significantly more frequently in HF than in CTL. TPQ prevented ADO-induced rate slowing in HF. SIGNIFICANCE An increase in A1R and GIRK expression enhances IKAdo, causing hyperpolarization, and subsequent negative chronotropic effects in canine chronic HF at relevant [ADO]. GIRK blockade may be a useful strategy to mitigate bradycardia in HF.
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Affiliation(s)
- Victor P Long
- College of Pharmacy, The Ohio State University, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Ingrid M Bonilla
- College of Pharmacy, The Ohio State University, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Stephen Baine
- College of Pharmacy, The Ohio State University, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Patric Glynn
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Sanjay Kumar
- Department of Pharmacology, University of Arizona, Tucson, AZ, USA
| | - Karsten Schober
- College of Veterinary Medicine, The Ohio State University, Columbus, OH
| | | | - Raul Weiss
- Division of Cardiovascular Medicine, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Nam Y Lee
- Department of Pharmacology, University of Arizona, Tucson, AZ, USA
| | - Peter J Mohler
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Sandor Györke
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Thomas J Hund
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Vadim V Fedorov
- Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Cynthia A Carnes
- College of Pharmacy, The Ohio State University, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA.
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Li D, Jin T, Gazgalis D, Cui M, Logothetis DE. On the mechanism of GIRK2 channel gating by phosphatidylinositol bisphosphate, sodium, and the Gβγ dimer. J Biol Chem 2019; 294:18934-18948. [PMID: 31659119 DOI: 10.1074/jbc.ra119.010047] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 10/21/2019] [Indexed: 12/19/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels belong to the inward-rectifier K+ (Kir) family, are abundantly expressed in the heart and the brain, and require that phosphatidylinositol bisphosphate is present so that intracellular channel-gating regulators such as Gβγ and Na+ ions can maintain the channel-open state. However, despite high-resolution structures (GIRK2) and a large number of functional studies, we do not have a coherent picture of how Gβγ and Na+ ions control gating of GIRK2 channels. Here, we utilized computational modeling and all-atom microsecond-scale molecular dynamics simulations to determine which gates are controlled by Na+ and Gβγ and how each regulator uses the channel domain movements to control gate transitions. We found that Na+ ions control the cytosolic gate of the channel through an anti-clockwise rotation, whereas Gβγ stabilizes the transmembrane gate in the open state through a rocking movement of the cytosolic domain. Both effects alter the way in which the channel interacts with phosphatidylinositol bisphosphate and thereby stabilizes the open states of the respective gates. These studies of GIRK channel dynamics present for the first time a comprehensive structural model that is consistent with the great body of literature on GIRK channel function.
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Affiliation(s)
- Dailin Li
- Key Laboratory of Environmental Biotechnology, Fujian Province University, Xiamen University of Technology, Xiamen, 361024 China; Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Bouve College of Health Sciences, Boston, Massachusetts 02115.
| | - Taihao Jin
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Bouve College of Health Sciences, Boston, Massachusetts 02115
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Bouve College of Health Sciences, Boston, Massachusetts 02115
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Bouve College of Health Sciences, Boston, Massachusetts 02115
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, Northeastern University School of Pharmacy, Bouve College of Health Sciences, Boston, Massachusetts 02115.
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Trads JB, Hüll K, Matsuura BS, Laprell L, Fehrentz T, Görldt N, Kozek KA, Weaver CD, Klöcker N, Barber DM, Trauner D. Sign Inversion in Photopharmacology: Incorporation of Cyclic Azobenzenes in Photoswitchable Potassium Channel Blockers and Openers. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201905790] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Julie B. Trads
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
- Center for DNA Nanotechnology Department of Chemistry and iNANO Aarhus University Gustav Wieds Vej 14 8000 Aarhus C Denmark
| | - Katharina Hüll
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
- Department of Chemistry New York University 100 Washington Square East New York NY 10003-6699 USA
| | - Bryan S. Matsuura
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
- Department of Chemistry New York University 100 Washington Square East New York NY 10003-6699 USA
| | - Laura Laprell
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
| | - Timm Fehrentz
- Institute of Neural and Sensory Physiology, Medical Faculty University of Düsseldorf Düsseldorf Germany
| | - Nicole Görldt
- Institute of Neural and Sensory Physiology, Medical Faculty University of Düsseldorf Düsseldorf Germany
| | - Krystian A. Kozek
- Department of Pharmacology Vanderbilt University School of Medicine Nashville TN USA
| | - C. David Weaver
- Departments of Pharmacology and Chemistry Institute of Chemical Biology Vanderbilt University School of Medicine Nashville TN USA
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty University of Düsseldorf Düsseldorf Germany
| | - David M. Barber
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
| | - Dirk Trauner
- Department of Chemistry and Center for Integrated Protein Science (CIPSM) Ludwig Maximilian University Munich Butenandtstr. 5–13 81377 Munich Germany
- Department of Chemistry New York University 100 Washington Square East New York NY 10003-6699 USA
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35
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Trads JB, Hüll K, Matsuura BS, Laprell L, Fehrentz T, Görldt N, Kozek KA, Weaver CD, Klöcker N, Barber DM, Trauner D. Sign Inversion in Photopharmacology: Incorporation of Cyclic Azobenzenes in Photoswitchable Potassium Channel Blockers and Openers. Angew Chem Int Ed Engl 2019; 58:15421-15428. [PMID: 31441199 DOI: 10.1002/anie.201905790] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/30/2019] [Indexed: 01/22/2023]
Abstract
Photopharmacology relies on ligands that change their pharmacodynamics upon photoisomerization. Many of these ligands are azobenzenes that are thermodynamically more stable in their elongated trans-configuration. Often, they are biologically active in this form and lose activity upon irradiation and photoisomerization to their cis-isomer. Recently, cyclic azobenzenes, so-called diazocines, have emerged, which are thermodynamically more stable in their bent cis-form. Incorporation of these switches into a variety of photopharmaceuticals could convert dark-active ligands into dark-inactive ligands, which is preferred in most biological applications. This "pharmacological sign-inversion" is demonstrated for a photochromic blocker of voltage-gated potassium channels, termed CAL, and a photochromic opener of G protein-coupled inwardly rectifying potassium (GIRK) channels, termed CLOGO.
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Affiliation(s)
- Julie B Trads
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany.,Center for DNA Nanotechnology, Department of Chemistry and iNANO, Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark
| | - Katharina Hüll
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany.,Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003-6699, USA
| | - Bryan S Matsuura
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany.,Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003-6699, USA
| | - Laura Laprell
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany
| | - Timm Fehrentz
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Nicole Görldt
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - Krystian A Kozek
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - C David Weaver
- Departments of Pharmacology and Chemistry, Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Medical Faculty, University of Düsseldorf, Düsseldorf, Germany
| | - David M Barber
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany
| | - Dirk Trauner
- Department of Chemistry and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Butenandtstr. 5-13, 81377, Munich, Germany.,Department of Chemistry, New York University, 100 Washington Square East, New York, NY, 10003-6699, USA
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36
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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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38
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GIRK Channel Activity in Dopamine Neurons of the Ventral Tegmental Area Bidirectionally Regulates Behavioral Sensitivity to Cocaine. J Neurosci 2019; 39:3600-3610. [PMID: 30837265 DOI: 10.1523/jneurosci.3101-18.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/17/2019] [Accepted: 02/22/2019] [Indexed: 12/19/2022] Open
Abstract
Dopamine (DA) neurons of the VTA have been widely implicated in the cellular and behavioral responses to drugs of abuse. Inhibitory G protein signaling mediated by GABAB receptors (GABABRs) and D2 DA receptors (D2Rs) regulates the excitability of VTA DA neurons, DA neurotransmission, and behaviors modulated by DA. Most of the somatodendritic inhibitory effect of GABABR and D2R activation on DA neurons reflects the activation of G protein-gated inwardly rectifying K+ (GIRK) channels. Furthermore, GIRK-dependent signaling in VTA DA neurons can be weakened by exposure to psychostimulants and strengthened by phasic DA neuron firing. The objective of this study was to determine how the strength of GIRK channel activity in VTA DA neurons influences sensitivity to cocaine. We used a Cre-dependent viral strategy to overexpress the individual GIRK channel subunits in VTA DA neurons of male and female adult mice, leading to enhancement (GIRK2) or suppression (GIRK3) of GIRK channel activity. Overexpression of GIRK3 decreased somatodendritic GABABR- and D2R-dependent signaling and increased cocaine-induced locomotor activity, whereas overexpression of GIRK2 increased GABABR-dependent signaling and decreased cocaine-induced locomotion. Neither manipulation impacted anxiety- or depression-related behavior, despite the link between such behaviors and DA signaling. Together, these data show that behavioral sensitivity to cocaine in mice is inversely proportional to the strength of GIRK channel activity in VTA DA neurons and suggest that direct activators of the unique VTA DA neuron GIRK channel subtype (GIRK2/GIRK3 heteromer) could represent a promising therapeutic target for treatment of addiction.SIGNIFICANCE STATEMENT Inhibitory G protein signaling in dopamine (DA) neurons, including that mediated by G protein-gated inwardly rectifying K+ (GIRK) channels, has been implicated in behavioral sensitivity to cocaine. Here, we used a viral approach to bidirectionally manipulate GIRK channel activity in DA neurons of the VTA. We found that decreasing GIRK channel activity in VTA DA neurons increased behavioral sensitivity to cocaine, whereas increasing GIRK channel activity decreased behavioral sensitivity to cocaine. These manipulations did not alter anxiety- or depression-related behaviors. These data highlight the unique GIRK channel subtype in VTA DA neurons as a possible therapeutic target for addiction.
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Mutual action by Gγ and Gβ for optimal activation of GIRK channels in a channel subunit-specific manner. Sci Rep 2019; 9:508. [PMID: 30679535 PMCID: PMC6346094 DOI: 10.1038/s41598-018-36833-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/29/2018] [Indexed: 01/06/2023] Open
Abstract
The tetrameric G protein-gated K+ channels (GIRKs) mediate inhibitory effects of neurotransmitters that activate Gi/o-coupled receptors. GIRKs are activated by binding of the Gβγ dimer, via contacts with Gβ. Gγ underlies membrane targeting of Gβγ, but has not been implicated in channel gating. We observed that, in Xenopus oocytes, expression of Gγ alone activated homotetrameric GIRK1* and heterotetrameric GIRK1/3 channels, without affecting the surface expression of GIRK or Gβ. Gγ and Gβ acted interdependently: the effect of Gγ required the presence of ambient Gβ and was enhanced by low doses of coexpressed Gβ, whereas excess of either Gβ or Gγ imparted suboptimal activation, possibly by sequestering the other subunit “away” from the channel. The unique distal C-terminus of GIRK1, G1-dCT, was important but insufficient for Gγ action. Notably, GIRK2 and GIRK1/2 were not activated by Gγ. Our results suggest that Gγ regulates GIRK1* and GIRK1/3 channel’s gating, aiding Gβ to trigger the channel’s opening. We hypothesize that Gγ helps to relax the inhibitory effect of a gating element (“lock”) encompassed, in part, by the G1-dCT; GIRK2 acts to occlude the effect of Gγ, either by setting in motion the same mechanism as Gγ, or by triggering an opposing gating effect.
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Kozek KA, Du Y, Sharma S, Prael FJ, Spitznagel BD, Kharade SV, Denton JS, Hopkins CR, Weaver CD. Discovery and Characterization of VU0529331, a Synthetic Small-Molecule Activator of Homomeric G Protein-Gated, Inwardly Rectifying, Potassium (GIRK) Channels. ACS Chem Neurosci 2019; 10:358-370. [PMID: 30136838 PMCID: PMC6528656 DOI: 10.1021/acschemneuro.8b00287] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
G protein-gated, inwardly rectifying, potassium (GIRK) channels are important regulators of cellular excitability throughout the body. GIRK channels are heterotetrameric and homotetrameric combinations of the Kir3.1-4 (GIRK1-4) subunits. Different subunit combinations are expressed throughout the central nervous system (CNS) and the periphery, and most of these combinations contain a GIRK1 subunit. For example, the predominance of GIRK channels in the CNS are composed of GIRK1 and GIRK2 subunits, while the GIRK channels in cardiac atrial myocytes are made up mostly of GIRK1 and GIRK4 subunits. Although the vast majority of GIRK channels contain a GIRK1 subunit, discrete populations of cells that express non-GIRK1-containing GIRK (non-GIRK1/X) channels do exist. For instance, dopaminergic neurons in the ventral tegmental area of the brain, associated with addiction and reward, do not express the GIRK1 subunit. Targeting these non-GIRK1/X channels with subunit-selective pharmacological probes could lead to important insights into how GIRK channels are involved in reward and addiction. Such insights may, in turn, reveal therapeutic opportunities for the treatment or prevention of addiction. Previously, our laboratory discovered small molecules that can specifically modulate the activity of GIRK1-containing GIRK channels. However, efforts to generate compounds active on non-GIRK1/X channels from these scaffolds have been unsuccessful. Recently, ivermectin was shown to modulate non-GIRK1/X channels, and historically, ivermectin is known to modulate a wide variety of neuronal channels and receptors. Further, ivermectin is a complex natural product, which makes it a challenging starting point for development of more selective, effective, and potent compounds. Thus, while ivermectin provides proof-of-concept as a non-GIRK1/X channel activator, it is of limited utility. Therefore, we sought to discover a synthetic small molecule that would serve as a starting point for the development of non-GIRK1/X channel modulators. To accomplish this, we used a high-throughput thallium flux assay to screen a 100 000-compound library in search of activators of homomeric GIRK2 channels. Using this approach, we discovered VU0529331, the first synthetic small molecule reported to activate non-GIRK1/X channels, to our knowledge. This discovery represents the first step toward developing potent and selective non-GIRK1/X channel probes. Such molecules will help elucidate the role of GIRK channels in addiction, potentially establishing a foundation for future development of therapies utilizing targeted GIRK channel modulation.
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Affiliation(s)
- Krystian A. Kozek
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Medical Scientist Training Program, Vanderbilt University, Nashville, Tennessee, USA
| | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Swagat Sharma
- Department of Pharmaceutical Sciences, Center for Drug Discovery, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Francis J. Prael
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Brittany D. Spitznagel
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Sujay V. Kharade
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Jerod S. Denton
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Corey R. Hopkins
- Department of Pharmaceutical Sciences, Center for Drug Discovery, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
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Krebs K, Pfeil EM, Simon K, Grundmann M, Häberlein F, Bautista-Aguilera OM, Gütschow M, Weaver CD, Fleischmann BK, Kostenis E. Label-Free Whole Cell Biosensing for High-Throughput Discovery of Activators and Inhibitors Targeting G Protein-Activated Inwardly Rectifying Potassium Channels. ACS OMEGA 2018; 3:14814-14823. [PMID: 30555990 PMCID: PMC6289404 DOI: 10.1021/acsomega.8b02254] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 10/22/2018] [Indexed: 06/09/2023]
Abstract
Dynamic mass redistribution (DMR) and cellular dielectric spectroscopy (CDS) are label-free biosensor technologies that capture real-time integrated cellular responses upon exposure to extra- and intracellular stimuli. They register signaling routes that are accompanied by cell shape changes and/or molecular movement of cells proximal to the biosensor to which they are attached. Here, we report the unexpected observation that robust DMR and CDS signatures are also elicited upon direct stimulation of G protein-activated inwardly rectifying potassium (GIRK) channels, which are involved in the regulation of excitability in the heart and brain. Using ML297, a small-molecule GIRK activator, along with channel blockers and cytoskeletal network inhibitors, we found that GIRK activation exerts its effects on cell shape by a mechanism which depends on actin but not the microtubule network. Because label-free real-time biosensing (i) quantitatively determines concentration dependency of GIRK activators, (ii) accurately assesses the impact of GIRK channel blockers, (iii) is high throughput-compatible, and (iv) visualizes previously unknown cellular consequences downstream of direct GIRK activation, we do not only provide a novel experimental strategy for identification of GIRK ligands but also an entirely new angle to probe GIRK (ligand) biology. We envision that DMR and CDS may add to the repertoire of technologies for systematic exploitation of ion channel function and, in turn, to the identification of novel GIRK ligands in order to treat cardiovascular and neurological disorders.
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Affiliation(s)
- Katrin
M. Krebs
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
- Research
Training Group 1873, University of Bonn, Bonn, Germany
| | - Eva M. Pfeil
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
- Research
Training Group 1873, University of Bonn, Bonn, Germany
| | - Katharina Simon
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Manuel Grundmann
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Felix Häberlein
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
| | - Oscar M. Bautista-Aguilera
- Pharmaceutical
Chemistry I, Institute of Pharmacy, University
of Bonn, An der Immenburg
4, 53121 Bonn, Germany
| | - Michael Gütschow
- Pharmaceutical
Chemistry I, Institute of Pharmacy, University
of Bonn, An der Immenburg
4, 53121 Bonn, Germany
| | - C. David Weaver
- Vanderbilt
Institute of Chemical Biology, Department of Pharmacology and Department
of Chemistry, Vanderbilt University, Nashville, 37232 Tennessee, United States
| | - Bernd K. Fleischmann
- Institute
of Physiology I, Life and Brain Center, Medical Faculty, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn, Germany
| | - Evi Kostenis
- Molecular,
Cellular and Pharmacobiology Section, Institute for Pharmaceutical
Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
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Inhibition of Pyramidal Neurons in the Basal Amygdala Promotes Fear Learning. eNeuro 2018; 5:eN-NWR-0272-18. [PMID: 30406197 PMCID: PMC6220591 DOI: 10.1523/eneuro.0272-18.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/08/2018] [Accepted: 10/12/2018] [Indexed: 12/16/2022] Open
Abstract
The basolateral amygdala complex, which contains the lateral (LA) and basal (BA) subnuclei, is a critical substrate of associative learning related to reward and aversive stimuli. Auditory fear conditioning studies in rodents have shown that the excitation of LA pyramidal neurons, driven by the inhibition of local GABAergic interneurons, is critical to fear memory formation. Studies examining the role of the BA in auditory fear conditioning, however, have yielded divergent outcomes. Here, we used a neuron-specific chemogenetic approach to manipulate the excitability of mouse BA neurons during auditory fear conditioning. We found that chemogenetic inhibition of BA GABA neurons, but not BA pyramidal neurons, impaired fear learning. Further, either chemogenetic stimulation of BA GABA neurons or chemogenetic inhibition of BA pyramidal neurons was sufficient to generate the formation of an association between a behavior and a neutral auditory cue. This chemogenetic memory required presentation of a discrete cue, and was not attributable to an effect of BA pyramidal neuron inhibition on general freezing behavior, locomotor activity, or anxiety. Collectively, these data suggest that BA GABA neuron activation and the subsequent inhibition of BA pyramidal neurons play important role in fear learning. Moreover, the roles of inhibitory signaling differ between the LA and BA, with excitation of pyramidal neurons promoting memory formation in the former, and inhibition of pyramidal neurons playing this role in the latter.
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Kummer KK, Kalpachidou T, Mitrić M, Langeslag M, Kress M. Altered Gene Expression in Prefrontal Cortex of a Fabry Disease Mouse Model. Front Mol Neurosci 2018; 11:201. [PMID: 30013462 PMCID: PMC6036252 DOI: 10.3389/fnmol.2018.00201] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/18/2018] [Indexed: 11/13/2022] Open
Abstract
Fabry disease is an X-chromosome linked hereditary disease that is caused by loss of function mutations in the α-galactosidase A (α-Gal A) gene, resulting in defective glycolipid degradation and subsequent accumulation of globotriaosylceramide (Gb3) in different tissues, including vascular endothelial cells and neurons in the peripheral and central nervous system. We recently reported a differential gene expression profile of α-Gal A(−/0) mouse dorsal root ganglia, an established animal model of Fabry disease, thereby providing new gene targets that might underlie the neuropathic pain related symptoms. To investigate the cognitive symptoms experienced by Fabry patients, we performed one-color based hybridization microarray expression profiling of prefrontal cortex samples from adult α-Gal A(−/0) mice and age-matched wildtype controls, followed by protein-protein interaction and pathway analyses for the differentially regulated mRNAs. We found that from a total of 381 differentially expressed genes, 135 genes were significantly upregulated, whereas 246 genes were significantly downregulated between α-Gal A(−/0) mice and wildtype controls. Enrichment analysis for downregulated genes revealed mainly immune related pathways, including immune/defense responses, regulation of cytokine production, as well as signaling and transport regulation pathways. Further analysis of the regulated genes revealed a large number of genes involved in neurodegeneration. The current analysis for the first time presents a differential gene expression profile of central nervous system tissue from α-Gal A(−/0) mice, thereby providing novel knowledge on the deregulation and a possible contribution of gene expression to Fabry disease related brain pathologies.
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Affiliation(s)
- Kai K Kummer
- Division of Physiology, Department of Physiology and Medical Physics Medical, University of Innsbruck, Innsbruck, Austria
| | - Theodora Kalpachidou
- Division of Physiology, Department of Physiology and Medical Physics Medical, University of Innsbruck, Innsbruck, Austria
| | - Miodrag Mitrić
- Division of Physiology, Department of Physiology and Medical Physics Medical, University of Innsbruck, Innsbruck, Austria
| | - Michiel Langeslag
- Division of Physiology, Department of Physiology and Medical Physics Medical, University of Innsbruck, Innsbruck, Austria
| | - Michaela Kress
- Division of Physiology, Department of Physiology and Medical Physics Medical, University of Innsbruck, Innsbruck, Austria
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Constitutive and Synaptic Activation of GIRK Channels Differentiates Mature and Newborn Dentate Granule Cells. J Neurosci 2018; 38:6513-6526. [PMID: 29915136 DOI: 10.1523/jneurosci.0674-18.2018] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/30/2018] [Accepted: 05/30/2018] [Indexed: 12/21/2022] Open
Abstract
Sparse neural activity in the dentate gyrus is enforced by powerful networks of inhibitory GABAergic interneurons in combination with low intrinsic excitability of the principal neurons, the dentate granule cells (GCs). Although the cellular and circuit properties that dictate synaptic inhibition are well studied, less is known about mechanisms that confer low GC intrinsic excitability. Here we demonstrate that intact G protein-mediated signaling contributes to the characteristic low resting membrane potential that differentiates mature dentate GCs from CA1 pyramidal cells and developing adult-born GCs. In mature GCs from male and female mice, intact G protein signaling robustly reduces intrinsic excitability, whereas deletion of G protein-activated inwardly rectifying potassium channel 2 (GIRK2) increases excitability and blocks the effects of G protein signaling on intrinsic properties. Similarly, pharmacological manipulation of GABAB receptors (GABABRs) or GIRK channels alters intrinsic excitability and GC spiking behavior. However, adult-born new GCs lack functional GIRK activity, with phasic and constitutive GABABR-mediated GIRK signaling appearing after several weeks of maturation. Phasic activation is interneuron specific, arising primarily from nNOS-expressing interneurons rather than parvalbumin- or somatostatin-expressing interneurons. Together, these results demonstrate that G protein signaling contributes to the intrinsic excitability that differentiates mature and developing dentate GCs and further suggest that late maturation of GIRK channel activity is poised to convert early developmental functions of GABAB receptor signaling into GABABR-mediated inhibition.SIGNIFICANCE STATEMENT The dentate gyrus exhibits sparse neural activity that is essential for the computational function of pattern separation. Sparse activity is ascribed to strong local inhibitory circuits in combination with low intrinsic excitability of the principal neurons, the granule cells. Here we show that constitutive activity of G protein-coupled inwardly rectifying potassium channels (GIRKs) underlies to the hallmark low resting membrane potential and input resistance of mature dentate neurons. Adult-born neurons initially lack functional GIRK channels, with constitutive and phasic GABAB receptor-mediated GIRK inhibition developing in tandem after several weeks of maturation. Our results reveal that GABAB/GIRK activity is an important determinant of low excitability of mature dentate granule cells that may contribute to sparse DG activity in vivo.
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Abstract
Opioids are the most commonly used and effective analgesic treatments for severe pain, but they have recently come under scrutiny owing to epidemic levels of abuse and overdose. These compounds act on the endogenous opioid system, which comprises four G protein-coupled receptors (mu, delta, kappa, and nociceptin) and four major peptide families (β-endorphin, enkephalins, dynorphins, and nociceptin/orphanin FQ). In this review, we first describe the functional organization and pharmacology of the endogenous opioid system. We then summarize current knowledge on the signaling mechanisms by which opioids regulate neuronal function and neurotransmission. Finally, we discuss the loci of opioid analgesic action along peripheral and central pain pathways, emphasizing the pain-relieving properties of opioids against the affective dimension of the pain experience.
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Affiliation(s)
- Gregory Corder
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, California 94304, USA; .,Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, California 94304, USA.,Department of Neurosurgery, Stanford University, Palo Alto, California 94304, USA.,Stanford Neurosciences Institute, Palo Alto, California 94304, USA
| | - Daniel C Castro
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri 63130, USA;
| | - Michael R Bruchas
- Department of Anesthesiology, Washington University in St. Louis, St. Louis, Missouri 63130, USA; .,Division of Basic Research, Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63130, USA.,Washington University Pain Center, Washington University School of Medicine, St. Louis, Missouri 63130, USA.,Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri 63130, USA.,Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, USA
| | - Grégory Scherrer
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, California 94304, USA; .,Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, California 94304, USA.,Department of Neurosurgery, Stanford University, Palo Alto, California 94304, USA.,Stanford Neurosciences Institute, Palo Alto, California 94304, USA.,New York Stem Cell Foundation - Robertson Investigator, Stanford University, Palo Alto, California 94304, USA
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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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Differential association of GABA B receptors with their effector ion channels in Purkinje cells. Brain Struct Funct 2017; 223:1565-1587. [PMID: 29177691 PMCID: PMC5869904 DOI: 10.1007/s00429-017-1568-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/10/2017] [Indexed: 11/23/2022]
Abstract
Metabotropic GABAB receptors mediate slow inhibitory effects presynaptically and postsynaptically through the modulation of different effector signalling pathways. Here, we analysed the distribution of GABAB receptors using highly sensitive SDS-digested freeze-fracture replica labelling in mouse cerebellar Purkinje cells. Immunoreactivity for GABAB1 was observed on presynaptic and, more abundantly, on postsynaptic compartments, showing both scattered and clustered distribution patterns. Quantitative analysis of immunoparticles revealed a somato-dendritic gradient, with the density of immunoparticles increasing 26-fold from somata to dendritic spines. To understand the spatial relationship of GABAB receptors with two key effector ion channels, the G protein-gated inwardly rectifying K+ (GIRK/Kir3) channel and the voltage-dependent Ca2+ channel, biochemical and immunohistochemical approaches were performed. Co-immunoprecipitation analysis demonstrated that GABAB receptors co-assembled with GIRK and CaV2.1 channels in the cerebellum. Using double-labelling immunoelectron microscopic techniques, co-clustering between GABAB1 and GIRK2 was detected in dendritic spines, whereas they were mainly segregated in the dendritic shafts. In contrast, co-clustering of GABAB1 and CaV2.1 was detected in dendritic shafts but not spines. Presynaptically, although no significant co-clustering of GABAB1 and GIRK2 or CaV2.1 channels was detected, inter-cluster distance for GABAB1 and GIRK2 was significantly smaller in the active zone than in the dendritic shafts, and that for GABAB1 and CaV2.1 was significantly smaller in the active zone than in the dendritic shafts and spines. Thus, GABAB receptors are associated with GIRK and CaV2.1 channels in different subcellular compartments. These data provide a better framework for understanding the different roles played by GABAB receptors and their effector ion channels in the cerebellar network.
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48
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Walsh KB, Gay EA, Blough BE, Geurkink DW. N-(2-methoxyphenyl) benzenesulfonamide, a novel regulator of neuronal G protein-gated inward rectifier K + channels. Eur J Pharmacol 2017; 815:233-240. [PMID: 28935562 DOI: 10.1016/j.ejphar.2017.09.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 02/07/2023]
Abstract
G protein-gated inward rectifier K+ (GIRK) channels are members of the super-family of proteins known as inward rectifier K+ (Kir) channels and are expressed throughout the peripheral and central nervous systems. Neuronal GIRK channels are the downstream targets of a number of neuromodulators including opioids, somatostatin, dopamine and cannabinoids. Previous studies have demonstrated that the ATP-sensitive K+ channel, another member of the Kir channel family, is regulated by sulfonamide drugs. Therefore, to determine if sulfonamides also modulate GIRK channels, we screened a library of arylsulfonamide compounds using a GIRK channel fluorescent assay that utilized pituitary AtT20 cells expressing GIRK channels along with the somatostatin type-2 and -5 receptors. Enhancement of the GIRK channel fluorescent signal by one compound, N-(2-methoxyphenyl) benzenesulfonamide (MPBS), was dependent on the activation of the channel by somatostatin. In whole-cell patch clamp experiments, application of MPBS both shifted the somatostatin concentration-response curve (EC50 = 3.5nM [control] vs.1.0nM [MPBS]) for GIRK channel activation and increased the maximum GIRK current measured with 100nM somatostatin. However, GIRK channel activation was not observed when MPBS was applied to the cells in the absence of somatostatin. While the MPBS structural analog 4-fluoro-N-(2-methoxyphenyl) benzenesulfonamide also augmented the somatostatin-induced GIRK fluorescent signal, no increase in the signal was observed with the sulfonamides tolbutamide, sulfapyridine and celecoxib. In conclusion, MPBS represents a novel prototypic GPCR-dependent regulator of neuronal GIRK channels.
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Affiliation(s)
- Kenneth B Walsh
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC, United States.
| | - Elaine A Gay
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, United States
| | - Bruce E Blough
- Center for Drug Discovery, Research Triangle Institute, Research Triangle Park, NC, United States
| | - David W Geurkink
- Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC, United States
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Sánchez-Rodríguez I, Temprano-Carazo S, Nájera A, Djebari S, Yajeya J, Gruart A, Delgado-García JM, Jiménez-Díaz L, Navarro-López JD. Activation of G-protein-gated inwardly rectifying potassium (Kir3/GirK) channels rescues hippocampal functions in a mouse model of early amyloid-β pathology. Sci Rep 2017; 7:14658. [PMID: 29116174 PMCID: PMC5676742 DOI: 10.1038/s41598-017-15306-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 10/25/2017] [Indexed: 12/15/2022] Open
Abstract
The hippocampus plays a critical role in learning and memory. Its correct performance relies on excitatory/inhibitory synaptic transmission balance. In early stages of Alzheimer’s disease (AD), neuronal hyperexcitability leads to network dysfunction observed in cortical regions such as the hippocampus. G-protein-gated potassium (GirK) channels induce neurons to hyperpolarize, contribute to the resting membrane potential and could compensate any excesses of excitation. Here, we have studied the relationship between GirK channels and hippocampal function in a mouse model of early AD pathology. Intracerebroventricular injections of amyloid-β (Aβ1-42) peptide—which have a causal role in AD pathogenesis—were performed to evaluate CA3–CA1 hippocampal synapse functionality in behaving mice. Aβ increased the excitability of the CA3–CA1 synapse, impaired long-term potentiation (LTP) and hippocampal oscillatory activity, and induced deficits in novel object recognition (NOR) tests. Injection of ML297 alone, a selective GirK activator, was also translated in LTP and NOR deficits. However, increasing GirK activity rescued all hippocampal deficits induced by Aβ due to the restoration of excitability values in the CA3–CA1 synapse. Our results show a synaptic mechanism, through GirK channel modulation, for the prevention of the hyperexcitability that causally contributes to synaptic, network, and cognitive deficits found in early AD pathogenesis.
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Affiliation(s)
- Irene Sánchez-Rodríguez
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Sara Temprano-Carazo
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Alberto Nájera
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Souhail Djebari
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain
| | - Javier Yajeya
- University of Salamanca, Instituto de Neurociencias de Castilla y León, Salamanca, Spain
| | - Agnès Gruart
- Pablo de Olavide University, Division of Neurosciences, Seville, Spain
| | | | - Lydia Jiménez-Díaz
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain.
| | - Juan D Navarro-López
- University of Castilla-La Mancha, NeuroPhysiology & Behavior Laboratory, Centro Regional de Investigaciones Biomédicas, School of Medicine of Ciudad Real, Ciudad Real, Spain.
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Wieting JM, Vadukoot AK, Sharma S, Abney KK, Bridges TM, Daniels JS, Morrison RD, Wickman K, Weaver CD, Hopkins CR. Discovery and Characterization of 1H-Pyrazol-5-yl-2-phenylacetamides as Novel, Non-Urea-Containing GIRK1/2 Potassium Channel Activators. ACS Chem Neurosci 2017; 8:1873-1879. [PMID: 28697302 DOI: 10.1021/acschemneuro.7b00217] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The G protein-gated inwardly-rectifying potassium channels (GIRK, Kir3) are a family of inward-rectifying potassium channels, and there is significant evidence supporting the roles of GIRKs in a number of physiological processes and as potential targets for numerous indications. Previously reported urea containing molecules as GIRK1/2 preferring activators have had significant pharmacokinetic (PK) liabilities. Here we report a novel series of 1H-pyrazolo-5-yl-2-phenylacetamides in an effort to improve upon the PK properties. This series of compounds display nanomolar potency as GIRK1/2 activators with improved brain distribution (rodent Kp > 0.6).
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Affiliation(s)
- Joshua M. Wieting
- Vanderbilt
Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Anish K. Vadukoot
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Swagat Sharma
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Kristopher K. Abney
- Department
of Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee 37208, United States
| | - Thomas M. Bridges
- Vanderbilt
Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - J. Scott Daniels
- Sano Informed Prescribing, Franklin, Tennessee 37067, United States
| | - Ryan D. Morrison
- Sano Informed Prescribing, Franklin, Tennessee 37067, United States
| | - Kevin Wickman
- Department
of Pharmacology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - C. David Weaver
- Department
of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, United States
- Vanderbilt
Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Corey R. Hopkins
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
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