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Früh S, Boudkkazi S, Koppensteiner P, Sereikaite V, Chen LY, Fernandez-Fernandez D, Rem PD, Ulrich D, Schwenk J, Chen Z, Le Monnier E, Fritzius T, Innocenti SM, Besseyrias V, Trovò L, Stawarski M, Argilli E, Sherr EH, van Bon B, Kamsteeg EJ, Iascone M, Pilotta A, Cutrì MR, Azamian MS, Hernández-García A, Lalani SR, Rosenfeld JA, Zhao X, Vogel TP, Ona H, Scott DA, Scheiffele P, Strømgaard K, Tafti M, Gassmann M, Fakler B, Shigemoto R, Bettler B. Monoallelic de novo AJAP1 loss-of-function variants disrupt trans-synaptic control of neurotransmitter release. SCIENCE ADVANCES 2024; 10:eadk5462. [PMID: 38985877 PMCID: PMC11235169 DOI: 10.1126/sciadv.adk5462] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 06/04/2024] [Indexed: 07/12/2024]
Abstract
Adherens junction-associated protein 1 (AJAP1) has been implicated in brain diseases; however, a pathogenic mechanism has not been identified. AJAP1 is widely expressed in neurons and binds to γ-aminobutyric acid type B receptors (GBRs), which inhibit neurotransmitter release at most synapses in the brain. Here, we show that AJAP1 is selectively expressed in dendrites and trans-synaptically recruits GBRs to presynaptic sites of neurons expressing AJAP1. We have identified several monoallelic AJAP1 variants in individuals with epilepsy and/or neurodevelopmental disorders. Specifically, we show that the variant p.(W183C) lacks binding to GBRs, resulting in the inability to recruit them. Ultrastructural analysis revealed significantly decreased presynaptic GBR levels in Ajap1-/- and Ajap1W183C/+ mice. Consequently, these mice exhibited reduced GBR-mediated presynaptic inhibition at excitatory and inhibitory synapses, along with impaired synaptic plasticity. Our study reveals that AJAP1 enables the postsynaptic neuron to regulate the level of presynaptic GBR-mediated inhibition, supporting the clinical relevance of loss-of-function AJAP1 variants.
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Affiliation(s)
- Simon Früh
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Sami Boudkkazi
- Institute of Physiology II, University of Freiburg, Hermann-Herderstrasse 7, 79104 Freiburg, Germany
| | - Peter Koppensteiner
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Vita Sereikaite
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Li-Yuan Chen
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 7, 1005 Lausanne, Switzerland
| | - Diego Fernandez-Fernandez
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Pascal D. Rem
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Daniel Ulrich
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Jochen Schwenk
- Institute of Physiology II, University of Freiburg, Hermann-Herderstrasse 7, 79104 Freiburg, Germany
| | - Ziyang Chen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Elodie Le Monnier
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Thorsten Fritzius
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | | | - Valérie Besseyrias
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Luca Trovò
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Michal Stawarski
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Emanuela Argilli
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
- Institute of Human Genetics and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Elliott H. Sherr
- Department of Neurology, University of California, San Francisco, San Francisco, CA 94158, USA
- Institute of Human Genetics and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Bregje van Bon
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525, Netherlands
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen 6525, Netherlands
| | - Maria Iascone
- Laboratorio Genetica Medica, ASST Papa Giovanni XXIII, Bergamo, Italy
| | | | | | - Mahshid S. Azamian
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Andrés Hernández-García
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Seema R. Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xiaonan Zhao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Baylor Genetics, Houston, TX 77021, USA
| | - Tiphanie P. Vogel
- Division of Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
| | - Herda Ona
- Division of Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
- Center for Human Immunobiology, Texas Children's Hospital, Houston, TX 77030, USA
| | - Daryl A. Scott
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Peter Scheiffele
- Biocenter, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Mehdi Tafti
- Department of Biomedical Sciences, Faculty of Biology and Medicine, University of Lausanne, Rue du Bugnon 7, 1005 Lausanne, Switzerland
| | - Martin Gassmann
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
| | - Bernd Fakler
- Institute of Physiology II, University of Freiburg, Hermann-Herderstrasse 7, 79104 Freiburg, Germany
| | - Ryuichi Shigemoto
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland
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Fritzius T, Tureček R, Fernandez-Fernandez D, Isogai S, Rem PD, Kralikova M, Gassmann M, Bettler B. Preassembly of specific Gβγ subunits at GABA B receptors through auxiliary KCTD proteins accelerates channel gating. Biochem Pharmacol 2024:116176. [PMID: 38555036 DOI: 10.1016/j.bcp.2024.116176] [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: 01/19/2024] [Revised: 03/15/2024] [Accepted: 03/26/2024] [Indexed: 04/02/2024]
Abstract
GABAB receptors (GBRs) are G protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the brain. GBRs regulate fast synaptic transmission by gating Ca2+ and K+ channels via the Gβγ subunits of the activated G protein. It has been demonstrated that auxiliary GBR subunits, the KCTD proteins, shorten onset and rise time and increase desensitization of receptor-induced K+ currents. KCTD proteins increase desensitization of K+ currents by scavenging Gβγ from the channel, yet the mechanism responsible for the rapid activation of K+ currents has remained elusive. In this study, we demonstrate that KCTD proteins preassemble Gβγ at GBRs. The preassembly obviates the need for diffusion-limited G protein recruitment to the receptor, thereby accelerating G protein activation and, as a result, K+ channel activation. Preassembly of Gβγ at the receptor relies on the interaction of KCTD proteins with a loop protruding from the seven-bladed propeller of Gβ subunits. The binding site is shared between Gβ1 and Gβ2, limiting the interaction of KCTD proteins to these particular Gβ isoforms. Substituting residues in the KCTD binding site of Gβ1 with those from Gβ3 hinders the preassembly of Gβγ with GBRs, delays onset and prolongs rise time of receptor-activated K+ currents. The KCTD-Gβ interface, therefore, represents a target for pharmacological modulation of channel gating by GBRs.
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Affiliation(s)
| | - Rostislav Tureček
- Department of Biomedicine, University of Basel, Basel, Switzerland; Department of Auditory Neuroscience, Institute of Experimental Medicine CAS, Prague, Czech Republic
| | | | - Shin Isogai
- Microbial Downstream Process Development, Lonza AG, Visp, Switzerland
| | - Pascal D Rem
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Michaela Kralikova
- Department of Auditory Neuroscience, Institute of Experimental Medicine CAS, Prague, Czech Republic
| | - Martin Gassmann
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, Basel, Switzerland.
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Liu P, Liu Z, Luo Q, Fu Q, Zhang X, Yu P, Zhou S, Wang Y, Zhang J, Chen S, Zhang H, Zhu Q, Qin T. A pan-cancer analysis of potassium channel tetramerization domain containing 12 in human cancer. Sci Rep 2023; 13:13898. [PMID: 37626178 PMCID: PMC10457314 DOI: 10.1038/s41598-023-41091-8] [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: 04/10/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023] Open
Abstract
Abnormal expression of the potassium channel tetramerization domain containing 12 (KCTD12) is closely related to the occurrence and development of various tumors, but a pan-cancer analysis of KCTD12 has not yet been conducted. We explored the association between KCTD12 and more than 30 human malignancies using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. First, the mRNA and protein levels of KCTD12 were examined and their correlations with tumor stage and survival were explored. Second, we analyzed the infiltration of CD8+ and CD4+ T cells and cancer-associated fibroblasts in tumors and explored the correlation between KCTD12 expression and tumor cell stemness, genomic heterogeneity, and diagnostic specificity. Finally, we explored the molecular mechanisms associated with KCTD12 using KEGG/GO analysis. The results showed that KCTD12 mRNA and protein expression levels decreased in most tumors was significantly associated with the prognosis of tumor patients, and the phosphorylation level of KCTD12 decreased in several tumors, such as S200 and T196, pancreatic adenocarcinoma (PAAD), lung adenocarcinoma (LUAD), and breast invasive cancer (BRCA). The expression of KCTD12 was positively correlated with the degree of cancer-associated fibroblasts infiltration in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), head and neck squamous cell carcinoma (HNSC), PAAD, and stomach adenocarcinoma (STAD). The relationship between KCTD12 expression and CD8+ and CD4+ T cell infiltration was also clarified. KCTD12 showed high diagnostic sensitivity for various types of tumors and may be involved in tumor cell biology by affecting tumor cell stemness, tumor burden, and other characteristics. Finally, we analyzed the molecular functions of KCTD12 and possible KEGG/GO signaling pathways. In this study, we developed a biological marker for diagnosis, prognosis, and immune infiltration of the pan-cancers.
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Affiliation(s)
- Pan Liu
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China
| | - Zhilan Liu
- Henan University of Chinese Medicine, Zhengzhou, 450000, China
| | - Qiankun Luo
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China
| | - Qiang Fu
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China
| | - Xu Zhang
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China
| | - Pengfei Yu
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China
| | - Shuai Zhou
- Translational Research Institute, Zhengzhou University People's Hospital, Zhengzhou, 450003, China
| | - Yingying Wang
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450003, China
| | - Jiali Zhang
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450003, China
| | - Song Chen
- Translational Research Institute, Zhengzhou University People's Hospital, Zhengzhou, 450003, China
- Academy of Medical Sciences, Zhengzhou University, Zhengzhou, 450003, China
| | - Hongwei Zhang
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China.
| | - Qinghai Zhu
- Zhumadian Central Hospital, No. 747, Zhonghua Road, Zhumadian, 463000, China.
| | - Tao Qin
- Department of Hepato-Biliary-Pancreatic Surgery, Zhengzhou University People's Hospital (Henan Provincial People's Hospital), No. 7 Weiwu Road, Jinshui District, Zhengzhou, 450000, China.
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Tureček R, Melichar A, Králíková M, Hrušková B. The role of GABA B receptors in the subcortical pathways of the mammalian auditory system. Front Endocrinol (Lausanne) 2023; 14:1195038. [PMID: 37635966 PMCID: PMC10456889 DOI: 10.3389/fendo.2023.1195038] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/24/2023] [Indexed: 08/29/2023] Open
Abstract
GABAB receptors are G-protein coupled receptors for the inhibitory neurotransmitter GABA. Functional GABAB receptors are formed as heteromers of GABAB1 and GABAB2 subunits, which further associate with various regulatory and signaling proteins to provide receptor complexes with distinct pharmacological and physiological properties. GABAB receptors are widely distributed in nervous tissue, where they are involved in a number of processes and in turn are subject to a number of regulatory mechanisms. In this review, we summarize current knowledge of the cellular distribution and function of the receptors in the inner ear and auditory pathway of the mammalian brainstem and midbrain. The findings suggest that in these regions, GABAB receptors are involved in processes essential for proper auditory function, such as cochlear amplifier modulation, regulation of spontaneous activity, binaural and temporal information processing, and predictive coding. Since impaired GABAergic inhibition has been found to be associated with various forms of hearing loss, GABAB dysfunction could also play a role in some pathologies of the auditory system.
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Affiliation(s)
- Rostislav Tureček
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Adolf Melichar
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Michaela Králíková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
| | - Bohdana Hrušková
- Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czechia
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Rem PD, Sereikaite V, Fernández-Fernández D, Reinartz S, Ulrich D, Fritzius T, Trovo L, Roux S, Chen Z, Rondard P, Pin JP, Schwenk J, Fakler B, Gassmann M, Barkat TR, Strømgaard K, Bettler B. Soluble amyloid-β precursor peptide does not regulate GABA B receptor activity. eLife 2023; 12:82082. [PMID: 36688536 PMCID: PMC9917443 DOI: 10.7554/elife.82082] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 01/22/2023] [Indexed: 01/24/2023] Open
Abstract
Amyloid-β precursor protein (APP) regulates neuronal activity through the release of secreted APP (sAPP) acting at cell surface receptors. APP and sAPP were reported to bind to the extracellular sushi domain 1 (SD1) of GABAB receptors (GBRs). A 17 amino acid peptide (APP17) derived from APP was sufficient for SD1 binding and shown to mimic the inhibitory effect of sAPP on neurotransmitter release and neuronal activity. The functional effects of APP17 and sAPP were similar to those of the GBR agonist baclofen and blocked by a GBR antagonist. These experiments led to the proposal that sAPP activates GBRs to exert its neuronal effects. However, whether APP17 and sAPP influence classical GBR signaling pathways in heterologous cells was not analyzed. Here, we confirm that APP17 binds to GBRs with nanomolar affinity. However, biochemical and electrophysiological experiments indicate that APP17 does not influence GBR activity in heterologous cells. Moreover, APP17 did not regulate synaptic GBR localization, GBR-activated K+ currents, neurotransmitter release, or neuronal activity in vitro or in vivo. Our results show that APP17 is not a functional GBR ligand and indicate that sAPP exerts its neuronal effects through receptors other than GBRs.
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Affiliation(s)
- Pascal Dominic Rem
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | - Vita Sereikaite
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, UniversitetsparkenCopenhagenDenmark
| | | | - Sebastian Reinartz
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | - Daniel Ulrich
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | - Thorsten Fritzius
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | - Luca Trovo
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | - Salomé Roux
- Institut de Génomique Fonctionnelle, Université de MontpellierMontpellierFrance
| | - Ziyang Chen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, UniversitetsparkenCopenhagenDenmark
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle, Université de MontpellierMontpellierFrance
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle, Université de MontpellierMontpellierFrance
| | - Jochen Schwenk
- Institute of Physiology, Faculty of Medicine, University of FreiburgFreiburgGermany
| | - Bernd Fakler
- Institute of Physiology, Faculty of Medicine, University of FreiburgFreiburgGermany
- CIBSS Center for Integrative Biological Signalling Studies, University of FreiburgFreiburgGermany
- Center for Basics in NeuroModulationFreiburgGermany
| | - Martin Gassmann
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
| | | | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, UniversitetsparkenCopenhagenDenmark
| | - Bernhard Bettler
- Department of Biomedicine, Pharmazentrum, University of BaselBaselSwitzerland
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Unravelling biological roles and mechanisms of GABA BR on addiction and depression through mood and memory disorders. Biomed Pharmacother 2022; 155:113700. [PMID: 36152411 DOI: 10.1016/j.biopha.2022.113700] [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: 08/12/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/23/2022] Open
Abstract
The metabotropic γ-aminobutyric acid type B receptor (GABABR) remains a hotspot in the recent research area. Being an idiosyncratic G-protein coupled receptor family member, the GABABR manifests adaptively tailored functionality under multifarious modulations by a constellation of agents, pointing to cross-talk between receptors and effectors that converge on the domains of mood and memory. This review systematically summarizes the latest achievements in signal transduction mechanisms of the GABABR-effector-regulator complex and probes how the up-and down-regulation of membrane-delimited GABABRs are associated with manifold intrinsic and extrinsic agents in synaptic strength and plasticity. Neuropsychiatric conditions depression and addiction share the similar pathophysiology of synapse inadaptability underlying negative mood-related processes, memory formations, and impairments. In the attempt to emphasize all convergent discoveries, we hope the insights gained on the GABABR system mechanisms of action are conducive to designing more therapeutic candidates so as to refine the prognosis rate of diseases and minimize side effects.
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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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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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Extracellular Signal-Regulated Kinases Mediate an Autoregulation of GABA B-Receptor-Activated Whole-Cell Current in Locus Coeruleus Neurons. Sci Rep 2020; 10:7869. [PMID: 32398643 PMCID: PMC7217949 DOI: 10.1038/s41598-020-64292-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 04/09/2020] [Indexed: 11/09/2022] Open
Abstract
The norepinephrine-releasing neurons in the locus coeruleus (LC) are well known to regulate wakefulness/arousal. They display active firing during wakefulness and a decreased discharge rate during sleep. We have previously reported that LC neurons express large numbers of GABAB receptors (GABABRs) located at peri-/extrasynaptic sites and are subject to tonic inhibition due to the continuous activation of GABABRs by ambient GABA, which is significantly higher during sleep than during wakefulness. In this study, we further showed using western blot analysis that the activation of GABABRs with baclofen could increase the level of phosphorylated extracellular signal-regulated kinase 1 (ERK1) in LC tissue. Recordings from LC neurons in brain slices showed that the inhibition of ERK1/2 with U0126 and FR180204 accelerated the decay of whole-cell membrane current induced by prolonged baclofen application. In addition, the inhibition of ERK1/2 also increased spontaneous firing and reduced tonic inhibition of LC neurons after prolonged exposure to baclofen. These results suggest a new role of GABABRs in mediating ERK1-dependent autoregulation of the stability of GABABR-activated whole-cell current, in addition to its well-known effect on gated potassium channels, to cause a tonic current in LC neurons.
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Direct Interaction of PP2A Phosphatase with GABA B Receptors Alters Functional Signaling. J Neurosci 2020; 40:2808-2816. [PMID: 32111696 PMCID: PMC7117905 DOI: 10.1523/jneurosci.2654-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 01/02/2020] [Accepted: 02/18/2020] [Indexed: 01/16/2023] Open
Abstract
Addictive drugs usurp the brain's intrinsic mechanism for reward, leading to compulsive and destructive behaviors. In the ventral tegmental area (VTA), the center of the brain's reward circuit, GABAergic neurons control the excitability of dopamine (DA) projection neurons and are the site of initial psychostimulant-dependent changes in signaling. Previous work established that cocaine/methamphetamine exposure increases protein phosphatase 2A (PP2A) activity, which dephosphorylates the GABABR2 subunit, promotes internalization of the GABAB receptor (GABABR) and leads to smaller GABABR-activated G-protein-gated inwardly rectifying potassium (GIRK) currents in VTA GABA neurons. How the actions of PP2A become selective for a particular signaling pathway is poorly understood. Here, we demonstrate that PP2A can associate directly with a short peptide sequence in the C terminal domain of the GABABR1 subunit, and that GABABRs and PP2A are in close proximity in rodent neurons (mouse/rat; mixed sexes). We show that this PP2A-GABABR interaction can be regulated by intracellular Ca2+ Finally, a peptide that potentially reduces recruitment of PP2A to GABABRs and thereby limits receptor dephosphorylation increases the magnitude of baclofen-induced GIRK currents. Thus, limiting PP2A-dependent dephosphorylation of GABABRs may be a useful strategy to increase receptor signaling for treating diseases.SIGNIFICANCE STATEMENT Dysregulation of GABAB receptors (GABABRs) underlies altered neurotransmission in many neurological disorders. Protein phosphatase 2A (PP2A) is involved in dephosphorylating and subsequent internalization of GABABRs in models of addiction and depression. Here, we provide new evidence that PP2A B55 regulatory subunit interacts directly with a small region of the C-terminal domain of the GABABR1 subunit, and that this interaction is sensitive to intracellular Ca2+ We demonstrate that a short peptide corresponding to the PP2A interaction site on GABABR1 competes for PP2A binding, enhances phosphorylation GABABR2 S783, and affects functional signaling through GIRK channels. Our study highlights how targeting PP2A dependent dephosphorylation of GABABRs may provide a specific strategy to modulate GABABR signaling in disease conditions.
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11
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van Coevorden-Hameete MH, de Bruijn MAAM, de Graaff E, Bastiaansen DAEM, Schreurs MWJ, Demmers JAA, Ramberger M, Hulsenboom ESP, Nagtzaam MMP, Boukhrissi S, Veldink JH, Verschuuren JJGM, Hoogenraad CC, Sillevis Smitt PAE, Titulaer MJ. The expanded clinical spectrum of anti-GABABR encephalitis and added value of KCTD16 autoantibodies. Brain 2020; 142:1631-1643. [PMID: 31009048 PMCID: PMC6536844 DOI: 10.1093/brain/awz094] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 01/29/2019] [Accepted: 02/16/2019] [Indexed: 11/27/2022] Open
Abstract
In this study we report the clinical features of 32 patients with gamma aminobutyric acid B receptor (GABABR) antibodies, identify additional autoantibodies in patients with anti-GABABR encephalitis that mark the presence of an underlying small cell lung carcinoma and optimize laboratory methods for the detection of GABABR antibodies. Patients (n = 3225) were tested for the presence of GABABR antibodies using cell-based assay, immunohistochemistry and live hippocampal neurons. Clinical data were obtained retrospectively. Potassium channel tetramerization domain-containing (KCTD)16 antibodies were identified by immunoprecipitation, mass spectrometry analysis and cell-based assays. KCTD16 antibodies were identified in 23/32 patients with anti-GABABR encephalitis, and in 1/26 patients with small cell lung carcinoma and Hu antibodies, but not in 329 healthy subjects and disease controls. Of the anti-GABABR encephalitis patients that were screened sufficiently, 18/19 (95%) patients with KCTD16 antibodies had a tumour versus 3/9 (33%) anti-GABABR encephalitis patients without KCTD16 antibodies (P = 0.001). In most cases this was a small cell lung carcinoma. Patients had cognitive or behavioural changes (97%) and prominent seizures (90%). Thirteen patients developed a refractory status epilepticus with intensive care unit admittance (42%). Strikingly, 4/32 patients had a rapidly progressive dementia. The addition of KCTD16 to the GABABR cell-based assay improved sensitivity of the in-house fixed cell-based assay, without loss of specificity. Twenty-two of 26 patients improved (partially) to immunotherapy or chemotherapy. Anti-GABABR encephalitis is a limbic encephalitis with prominent, severe seizures, but patients can also present with rapidly progressive dementia. The co-occurrence of KCTD16 antibodies points towards a paraneoplastic origin. The addition of KCTD16 improves the sensitivity of the cell-based assay.
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Affiliation(s)
- Marleen H van Coevorden-Hameete
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands.,Department of Biology, Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, CH, Utrecht, The Netherlands
| | - Marienke A A M de Bruijn
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Esther de Graaff
- Department of Biology, Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, CH, Utrecht, The Netherlands
| | | | - Marco W J Schreurs
- Department of Immunology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Jeroen A A Demmers
- Department of Biochemistry, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Melanie Ramberger
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Esther S P Hulsenboom
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Mariska M P Nagtzaam
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Sanae Boukhrissi
- Department of Immunology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Jan H Veldink
- Department of Neurology, University Medical Center Utrecht, Heidelberglaan 100, CX, Utrecht, The Netherlands
| | - Jan J G M Verschuuren
- Department of Neurology, Leiden University Medical Center, Albinusdreef 2, ZA, Leiden, The Netherlands
| | - Casper C Hoogenraad
- Department of Biology, Division of Cell Biology, Faculty of Science, Utrecht University, Padualaan 8, CH, Utrecht, The Netherlands
| | - Peter A E Sillevis Smitt
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
| | - Maarten J Titulaer
- Department of Neurology, Erasmus Medical Center, Dr. Molewaterplein 40, GD, Rotterdam, The Netherlands
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12
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Kniazeff J. The different aspects of the GABAB receptor allosteric modulation. FROM STRUCTURE TO CLINICAL DEVELOPMENT: ALLOSTERIC MODULATION OF G PROTEIN-COUPLED RECEPTORS 2020; 88:83-113. [DOI: 10.1016/bs.apha.2020.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Smaldone G, Balasco N, Pirone L, Caruso D, Di Gaetano S, Pedone EM, Vitagliano L. Molecular basis of the scalp-ear-nipple syndrome unraveled by the characterization of disease-causing KCTD1 mutants. Sci Rep 2019; 9:10519. [PMID: 31324836 PMCID: PMC6642198 DOI: 10.1038/s41598-019-46911-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 07/05/2019] [Indexed: 12/11/2022] Open
Abstract
The scalp-ear-nipple (SEN) syndrome is an autosomal-dominant disorder characterized by cutis aplasia of the scalp and malformations of breast, external ears, digits, and nails. Genetic analyses have shown that the disease is caused by missense mutations of the KCTD1 protein, although the functional/structural basis of SEN insurgence is hitherto unknown. With the aim of unravelling the molecular basis of the SEN syndrome associated with KCTD1 mutations we here expressed and characterized several disease causing mutants. A preliminary dissection of the protein provides insights into the role that individual domains play in KCTD1 stability. The characterization of SEN-causing mutants indicates that, although the mutation sites are located in distant regions of the BTB domain or of the pre-BTB region, all of them are unable to interact with the transcription factor AP-2α, a well-known KCTD1 biological partner. Notably, all mutations, including the one located in the pre-BTB region, produce a significant destabilization of the protein. The structural role of the pre-BTB region in KCTD1 and other proteins of the family is corroborated by its sequence conservation in orthologs and paralogs. Interestingly, SEN-causing mutations also favor the tendency of KCTD1 to adopt structural states that are characterized by the ability to bind the β-amyloid fluorescent dye thioflavin T. The formation of aggregation-prone species may have important implications for the disease etiology. Collectively, these findings provide an intriguing picture of the functional and structural alterations induced by KCTD1 mutations that ultimately lead to disease.
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Affiliation(s)
| | - Nicole Balasco
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Luciano Pirone
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Daniela Caruso
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy.,Università degli Studi della Campania "Luigi Vanvitelli", Viale Abramo Lincoln 5, 81100, Caserta, Italy
| | - Sonia Di Gaetano
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Emilia Maria Pedone
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134, Napoli, Italy.
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14
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Teng X, Aouacheria A, Lionnard L, Metz KA, Soane L, Kamiya A, Hardwick JM. KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders. CNS Neurosci Ther 2019; 25:887-902. [PMID: 31197948 PMCID: PMC6566181 DOI: 10.1111/cns.13156] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/02/2019] [Accepted: 05/13/2019] [Indexed: 12/12/2022] Open
Abstract
The underlying molecular basis for neurodevelopmental or neuropsychiatric disorders is not known. In contrast, mechanistic understanding of other brain disorders including neurodegeneration has advanced considerably. Yet, these do not approach the knowledge accrued for many cancers with precision therapeutics acting on well-characterized targets. Although the identification of genes responsible for neurodevelopmental and neuropsychiatric disorders remains a major obstacle, the few causally associated genes are ripe for discovery by focusing efforts to dissect their mechanisms. Here, we make a case for delving into mechanisms of the poorly characterized human KCTD gene family. Varying levels of evidence support their roles in neurocognitive disorders (KCTD3), neurodevelopmental disease (KCTD7), bipolar disorder (KCTD12), autism and schizophrenia (KCTD13), movement disorders (KCTD17), cancer (KCTD11), and obesity (KCTD15). Collective knowledge about these genes adds enhanced value, and critical insights into potential disease mechanisms have come from unexpected sources. Translation of basic research on the KCTD-related yeast protein Whi2 has revealed roles in nutrient signaling to mTORC1 (KCTD11) and an autophagy-lysosome pathway affecting mitochondria (KCTD7). Recent biochemical and structure-based studies (KCTD12, KCTD13, KCTD16) reveal mechanisms of regulating membrane channel activities through modulation of distinct GTPases. We explore how these seemingly varied functions may be disease related.
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Affiliation(s)
- Xinchen Teng
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and College of Pharmaceutical SciencesSoochow UniversitySuzhouChina
- W. Harry Feinstone Department of Molecular Microbiology and ImmunologyJohns Hopkins University Bloomberg School of Public HealthBaltimoreMaryland
| | - Abdel Aouacheria
- ISEM, Institut des Sciences de l'Evolution de Montpellier, CNRS, EPHE, IRDUniversité de MontpellierMontpellierFrance
| | - Loïc Lionnard
- ISEM, Institut des Sciences de l'Evolution de Montpellier, CNRS, EPHE, IRDUniversité de MontpellierMontpellierFrance
| | - Kyle A. Metz
- W. Harry Feinstone Department of Molecular Microbiology and ImmunologyJohns Hopkins University Bloomberg School of Public HealthBaltimoreMaryland
- Present address:
Feinberg School of MedicineNorthwestern UniversityChicagoUSA
| | - Lucian Soane
- W. Harry Feinstone Department of Molecular Microbiology and ImmunologyJohns Hopkins University Bloomberg School of Public HealthBaltimoreMaryland
| | - Atsushi Kamiya
- Department of Psychiatry and Behavioral SciencesJohns Hopkins School of MedicineBaltimoreMaryland
| | - J. Marie Hardwick
- W. Harry Feinstone Department of Molecular Microbiology and ImmunologyJohns Hopkins University Bloomberg School of Public HealthBaltimoreMaryland
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15
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Eszlari N, Millinghoffer A, Petschner P, Gonda X, Baksa D, Pulay AJ, Réthelyi JM, Breen G, Deakin JFW, Antal P, Bagdy G, Juhasz G. Genome-wide association analysis reveals KCTD12 and miR-383-binding genes in the background of rumination. Transl Psychiatry 2019; 9:119. [PMID: 30886212 PMCID: PMC6423133 DOI: 10.1038/s41398-019-0454-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 01/31/2019] [Accepted: 02/13/2019] [Indexed: 12/12/2022] Open
Abstract
Ruminative response style is a passive and repetitive way of responding to stress, associated with several disorders. Although twin and candidate gene studies have proven the genetic underpinnings of rumination, no genome-wide association study (GWAS) has been conducted yet. We performed a GWAS on ruminative response style and its two subtypes, brooding and reflection, among 1758 European adults recruited in the general population of Budapest, Hungary, and Manchester, United Kingdom. We evaluated single-nucleotide polymorphism (SNP)-based, gene-based and gene set-based tests, together with inferences on genes regulated by our most significant SNPs. While no genome-wide significant hit emerged at the SNP level, the association of rumination survived correction for multiple testing with KCTD12 at the gene level, and with the set of genes binding miR-383 at the gene set level. SNP-level results were concordant between the Budapest and Manchester subsamples for all three rumination phenotypes. SNP-level results and their links to brain expression levels based on external databases supported the role of KCTD12, SRGAP3, and SETD5 in rumination, CDH12 in brooding, and DPYSL5, MAPRE3, KCNK3, ATXN7L3B, and TPH2 in reflection, among others. The relatively low sample size is a limitation of our study. Results of the first GWAS on rumination identified genes previously implicated in psychiatric disorders underscoring the transdiagnostic nature of rumination, and pointed to the possible role of the dorsolateral prefrontal cortex, hippocampus, and cerebellum in this cognitive process.
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Affiliation(s)
- Nora Eszlari
- Department of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary. .,NAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary.
| | - Andras Millinghoffer
- 0000 0001 0942 9821grid.11804.3cNAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary ,0000 0001 2180 0451grid.6759.dDepartment of Measurement and Information Systems, Budapest University of Technology and Economics, Budapest, Hungary
| | - Peter Petschner
- 0000 0001 0942 9821grid.11804.3cDepartment of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cMTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - Xenia Gonda
- 0000 0001 0942 9821grid.11804.3cNAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cMTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cDepartment of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - Daniel Baksa
- 0000 0001 0942 9821grid.11804.3cDepartment of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cSE-NAP 2 Genetic Brain Imaging Migraine Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | - Attila J. Pulay
- 0000 0001 0942 9821grid.11804.3cDepartment of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary
| | - János M. Réthelyi
- 0000 0001 0942 9821grid.11804.3cDepartment of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cNAP2 Molecular Psychiatry Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary
| | - Gerome Breen
- 0000 0001 2322 6764grid.13097.3cSocial, Genetic and Developmental Psychiatry Centre, King’s College London, London, UK
| | - John Francis William Deakin
- 0000000121662407grid.5379.8Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK ,0000 0004 0417 0074grid.462482.eManchester Academic Health Sciences Centre, Manchester, UK ,0000 0004 0430 6955grid.450837.dGreater Manchester Mental Health NHS Foundation Trust, Prestwich, Manchester, M25 3BL UK
| | - Peter Antal
- 0000 0001 2180 0451grid.6759.dDepartment of Measurement and Information Systems, Budapest University of Technology and Economics, Budapest, Hungary
| | - Gyorgy Bagdy
- 0000 0001 0942 9821grid.11804.3cDepartment of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cNAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cMTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - Gabriella Juhasz
- 0000 0001 0942 9821grid.11804.3cDepartment of Pharmacodynamics, Faculty of Pharmacy, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cNAP-2-SE New Antidepressant Target Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cMTA-SE Neuropsychopharmacology and Neurochemistry Research Group, Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary ,0000 0001 0942 9821grid.11804.3cSE-NAP 2 Genetic Brain Imaging Migraine Research Group, Hungarian Brain Research Program, Semmelweis University, Budapest, Hungary ,0000000121662407grid.5379.8Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK ,0000 0004 0417 0074grid.462482.eManchester Academic Health Sciences Centre, Manchester, UK
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16
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Orts-Del'Immagine A, Pugh JR. Activity-dependent plasticity of presynaptic GABA B receptors at parallel fiber synapses. Synapse 2018; 72:e22027. [PMID: 29360168 DOI: 10.1002/syn.22027] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/05/2018] [Accepted: 01/21/2018] [Indexed: 01/10/2023]
Abstract
Parallel fiber synapses in the cerebellum express a wide range of presynaptic receptors. However, presynaptic receptor expression at individual parallel fiber synapses is quite heterogeneous, suggesting physiological mechanisms regulate presynaptic receptor expression. We investigated changes in presynaptic GABAB receptors at parallel fiber-stellate cell synapses in acute cerebellar slices from juvenile mice. GABAB receptor-mediated inhibition of excitatory postsynaptic currents (EPSCs) is remarkably diverse at these synapses, with transmitter release at some synapses inhibited by >50% and little or no inhibition at others. GABAB receptor-mediated inhibition was significantly reduced following 4 Hz parallel fiber stimulation but not after stimulation at other frequencies. The reduction in GABAB receptor-mediated inhibition was replicated by bath application of forskolin and blocked by application of a PKA inhibitor, suggesting activation of adenylyl cyclase and PKA are required. Immunolabeling for an extracellular domain of the GABAB2 subunit revealed reduced surface expression in the molecular layer after exposure to forskolin. GABAB receptor-mediated inhibition of action potential evoked calcium transients in parallel fiber varicosities was also reduced following bath application of forskolin, confirming presynaptic receptors are responsible for the reduced EPSC inhibition. These data demonstrate that presynaptic GABAB receptor expression can be a plastic property of synapses, which may compliment other forms of synaptic plasticity. This opens the door to novel forms of receptor plasticity previously confined primarily to postsynaptic receptors.
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Affiliation(s)
- Adeline Orts-Del'Immagine
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229
| | - Jason R Pugh
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229
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17
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TERUNUMA M. Diversity of structure and function of GABA B receptors: a complexity of GABA B-mediated signaling. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2018; 94:390-411. [PMID: 30541966 PMCID: PMC6374141 DOI: 10.2183/pjab.94.026] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 10/09/2018] [Indexed: 05/24/2023]
Abstract
γ-aminobutyric acid type B (GABAB) receptors are broadly expressed in the nervous system and play an important role in neuronal excitability. GABAB receptors are G protein-coupled receptors that mediate slow and prolonged inhibitory action, via activation of Gαi/o-type proteins. GABAB receptors mediate their inhibitory action through activating inwardly rectifying K+ channels, inactivating voltage-gated Ca2+ channels, and inhibiting adenylate cyclase. Functional GABAB receptors are obligate heterodimers formed by the co-assembly of R1 and R2 subunits. It is well established that GABAB receptors interact not only with G proteins and effectors but also with various proteins. This review summarizes the structure, subunit isoforms, and function of GABAB receptors, and discusses the complexity of GABAB receptors, including how receptors are localized in specific subcellular compartments, the mechanism regulating cell surface expression and mobility of the receptors, and the diversity of receptor signaling through receptor crosstalk and interacting proteins.
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Affiliation(s)
- Miho TERUNUMA
- Division of Oral Biochemistry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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18
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Kahanovitch U, Berlin S, Dascal N. Collision coupling in the GABA
B
receptor–G protein–GIRK signaling cascade. FEBS Lett 2017; 591:2816-2825. [DOI: 10.1002/1873-3468.12756] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 07/11/2017] [Accepted: 07/12/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Uri Kahanovitch
- Department of Physiology and Pharmacology Sackler School of Medicine Tel Aviv University Israel
| | - Shai Berlin
- Department of Physiology and Pharmacology Sackler School of Medicine Tel Aviv University Israel
| | - Nathan Dascal
- Department of Physiology and Pharmacology Sackler School of Medicine Tel Aviv University Israel
- Sagol School of Neuroscience Tel Aviv University Israel
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19
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Cannabinoid CB1 and CB2 receptors differentially modulate L- and T-type Ca 2+ channels in rat retinal ganglion cells. Neuropharmacology 2017; 124:143-156. [PMID: 28431968 DOI: 10.1016/j.neuropharm.2017.04.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 03/15/2017] [Accepted: 04/17/2017] [Indexed: 01/09/2023]
Abstract
Endocannabinoid signaling system is involved in regulating multiple neuronal functions in the central nervous system by activating G-protein coupled cannabinoid CB1 and CB2 receptors (CB1Rs and CB2Rs). Growing evidence has shown that CB1Rs and CB2Rs are extensively expressed in retinal ganglion cells (RGCs). Here, modulation of L- and T-types Ca2+ channels by activating CB1Rs and CB2Rs in RGCs was investigated. Triple immunofluorescent staining showed that L-type subunit CaV1.2 was co-localized with T-type subunits (CaV3.1, CaV3.2 and CaV3.3) in rat RGCs. In acutely isolated rat RGCs, the CB1R agonist WIN55212-2 suppressed both peak and steady-state Ca2+ currents in a dose-dependent manner, with IC50 being 9.6 μM and 8.4 μM, respectively. It was further shown that activation of CB1Rs by WIN55212-2 or ACEA, another CB1R agonist, significantly suppressed both L- and T-type Ca2+ currents, and shifted inactivation curve of T-type one toward hyperpolarization direction. While the effect on L-type Ca2+ channels was mediated by intracellular cAMP/protein kinase A (PKA), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and calcium/calmodulin-dependent protein kinase II (CaMKII) signaling pathways, only CaMKII signaling pathway was involved in the effect on T-type Ca2+ channels. Furthermore, CB65 and HU308, two specific CB2R agonists, significantly suppressed T-type Ca2+ channels, which was mediated by intracellular cAMP/PKA and CaMKII signaling pathways, but had no effect on L-type channels. These results imply that endogenous cannabinoids may modulate the excitability and the output of RGCs by differentially suppressing the activity of L- and T-type Ca2+ channels through activation of CB1Rs and CB2Rs. This article is part of the Special Issue entitled "A New Dawn in Cannabinoid Neurobiology".
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20
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KCTD Hetero-oligomers Confer Unique Kinetic Properties on Hippocampal GABAB Receptor-Induced K+ Currents. J Neurosci 2016; 37:1162-1175. [PMID: 28003345 DOI: 10.1523/jneurosci.2181-16.2016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/29/2016] [Accepted: 12/12/2016] [Indexed: 11/21/2022] Open
Abstract
GABAB receptors are the G-protein coupled receptors for the main inhibitory neurotransmitter in the brain, GABA. GABAB receptors were shown to associate with homo-oligomers of auxiliary KCTD8, KCTD12, KCTD12b, and KCTD16 subunits (named after their T1 K+-channel tetramerization domain) that regulate G-protein signaling of the receptor. Here we provide evidence that GABAB receptors also associate with hetero-oligomers of KCTD subunits. Coimmunoprecipitation experiments indicate that two-thirds of the KCTD16 proteins in the hippocampus of adult mice associate with KCTD12. We show that the KCTD proteins hetero-oligomerize through self-interacting T1 and H1 homology domains. Bioluminescence resonance energy transfer measurements in live cells reveal that KCTD12/KCTD16 hetero-oligomers associate with both the receptor and the G-protein. Electrophysiological experiments demonstrate that KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties on G-protein-activated Kir3 currents. During prolonged receptor activation (one min) KCTD12/KCTD16 hetero-oligomers produce moderately desensitizing fast deactivating K+ currents, whereas KCTD12 and KCTD16 homo-oligomers produce strongly desensitizing fast deactivating currents and nondesensitizing slowly deactivating currents, respectively. During short activation (2 s) KCTD12/KCTD16 hetero-oligomers produce nondesensitizing slowly deactivating currents. Electrophysiological recordings from hippocampal neurons of KCTD knock-out mice are consistent with these findings and indicate that KCTD12/KCTD16 hetero-oligomers increase the duration of slow IPSCs. In summary, our data demonstrate that simultaneous assembly of distinct KCTDs at the receptor increases the molecular and functional repertoire of native GABAB receptors and modulates physiologically induced K+ current responses in the hippocampus. SIGNIFICANCE STATEMENT The KCTD proteins 8, 12, and 16 are auxiliary subunits of GABAB receptors that differentially regulate G-protein signaling of the receptor. The KCTD proteins are generally assumed to function as homo-oligomers. Here we show that the KCTD proteins also assemble hetero-oligomers in all possible dual combinations. Experiments in live cells demonstrate that KCTD hetero-oligomers form at least tetramers and that these tetramers directly interact with the receptor and the G-protein. KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties to GABAB receptor-induced Kir3 currents in heterologous cells. KCTD12/KCTD16 hetero-oligomers are abundant in the hippocampus, where they prolong the duration of slow IPSCs in pyramidal cells. Our data therefore support that KCTD hetero-oligomers modulate physiologically induced K+ current responses in the brain.
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21
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Pirone L, Smaldone G, Esposito C, Balasco N, Petoukhov MV, Spilotros A, Svergun DI, Di Gaetano S, Vitagliano L, Pedone EM. Proteins involved in sleep homeostasis: Biophysical characterization of INC and its partners. Biochimie 2016; 131:106-114. [PMID: 27678190 DOI: 10.1016/j.biochi.2016.09.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 09/22/2016] [Accepted: 09/22/2016] [Indexed: 12/29/2022]
Abstract
The insomniac protein of Drosophila melanogaster (INC) has a crucial role in sleep homeostasis as flies lacking the inc gene exhibit strikingly reduced and poorly consolidated sleep. Nevertheless, in vitro characterizations of INC biophysical properties and partnerships have not been yet reported. Here we report the heterologous expression of the protein and its characterization using a number of different techniques. Present data indicate that INC is endowed with a remarkable stability, which results from the cooperation of the two protein domains. Moreover, we also demonstrated and quantified the ability of INC to recognize its potential partners Cul3 and dGRASP. Taking into account the molecular organization of the protein, these two partners may be anchored simultaneously. Although there is no evident relationship between the reported INC functions and dGRASP binding, our data suggest that INC may cooperate as ligase adaptor to dGRASP ubiquitination. SAXS data collected on the complex between INC and Cul3, which represent the first structural characterization of this type of assemblies, clearly highlight the highly dynamic nature of these complexes. This strongly suggests that the functional behavior of these proteins cannot be understood if dynamic effects are not considered. Finally, the strict analogy of the biochemical/biophysical properties of INC and of its human homolog KCTD5 may reliably indicate that this latter protein and/or the closely related proteins KCTD2/KCTD17 may play important roles in human sleep regulation.
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Affiliation(s)
- Luciano Pirone
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy
| | | | - Carla Esposito
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy
| | - Nicole Balasco
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy
| | - Maxim V Petoukhov
- European Molecular Biology Laboratory, Hamburg Outstation, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Alessandro Spilotros
- European Molecular Biology Laboratory, Hamburg Outstation, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Dmitri I Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, c/o DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Sonia Di Gaetano
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy.
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy.
| | - Emilia Maria Pedone
- Institute of Biostructures and Bioimaging, C.N.R., Via Mezzocannone 16, 80134 Napoli, Italy.
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22
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Smaldone G, Pirone L, Pedone E, Marlovits T, Vitagliano L, Ciccarelli L. The BTB domains of the potassium channel tetramerization domain proteins prevalently assume pentameric states. FEBS Lett 2016; 590:1663-71. [PMID: 27152988 DOI: 10.1002/1873-3468.12203] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 04/21/2016] [Accepted: 04/26/2016] [Indexed: 01/05/2023]
Abstract
Potassium channel tetramerization domain-containing (KCTD) proteins are involved in fundamental physio-pathological processes. Here, we report an analysis of the oligomeric state of the Bric-à-brack, Tram-track, Broad complex (BTB) domains of seven distinct KCTDs belonging to five major clades of the family evolution tree. Despite their functional and sequence variability, present electron microscopy data highlight the occurrence of well-defined pentameric states for all domains. Our data also show that these states coexist with alternative forms which include open pentamers. Thermal denaturation analyses conducted using KCTD1 as a model suggest that, in these proteins, different domains cooperate to their overall stability. Finally, negative-stain electron micrographs of KCTD6(BTB) in complex with Cullin3 show the presence of assemblies with a five-pointed pinwheel shape.
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Affiliation(s)
| | - Luciano Pirone
- Institute of Biostructures and Bioimaging, C.N.R., Napoli, Italy.,Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici (C.I.R.C.M.S.B.), Catania, Italy
| | - Emilia Pedone
- Institute of Biostructures and Bioimaging, C.N.R., Napoli, Italy
| | - Thomas Marlovits
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany.,Institute of Molecular Biotechnology (IMBA), Austrian Academy of Sciences, Vienna, Austria.,Research Institute of Molecular Pathology (IMP), Vienna, Austria
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging, C.N.R., Napoli, Italy
| | - Luciano Ciccarelli
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany.,Deutsches Elektronen-Synchrotron (DESY), Hamburg, Germany.,Institute of Molecular Biotechnology (IMBA), Austrian Academy of Sciences, Vienna, Austria.,Research Institute of Molecular Pathology (IMP), Vienna, Austria
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23
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Role of GABA(B) receptors in learning and memory and neurological disorders. Neurosci Biobehav Rev 2016; 63:1-28. [PMID: 26814961 DOI: 10.1016/j.neubiorev.2016.01.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/31/2015] [Accepted: 01/21/2016] [Indexed: 01/13/2023]
Abstract
Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations.
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24
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Cullin 3 Recognition Is Not a Universal Property among KCTD Proteins. PLoS One 2015; 10:e0126808. [PMID: 25974686 PMCID: PMC4431850 DOI: 10.1371/journal.pone.0126808] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 04/08/2015] [Indexed: 12/13/2022] Open
Abstract
Cullin 3 (Cul3) recognition by BTB domains is a key process in protein ubiquitination. Among Cul3 binders, a great attention is currently devoted to KCTD proteins, which are implicated in fundamental biological processes. On the basis of the high similarity of BTB domains of these proteins, it has been suggested that the ability to bind Cul3 could be a general property among all KCTDs. In order to gain new insights into KCTD functionality, we here evaluated and/or quantified the binding of Cul3 to the BTB of KCTD proteins, which are known to be involved either in cullin-independent (KCTD12 and KCTD15) or in cullin-mediated (KCTD6 and KCTD11) activities. Our data indicate that KCTD6BTB and KCTD11BTB bind Cul3 with high affinity forming stable complexes with 4:4 stoichiometries. Conversely, KCTD12BTB and KCTD15BTB do not interact with Cul3, despite the high level of sequence identity with the BTB domains of cullin binding KCTDs. Intriguingly, comparative sequence analyses indicate that the capability of KCTD proteins to recognize Cul3 has been lost more than once in distinct events along the evolution. Present findings also provide interesting clues on the structural determinants of Cul3-KCTD recognition. Indeed, the characterization of a chimeric variant of KCTD11 demonstrates that the swapping of α2β3 loop between KCTD11BTB and KCTD12BTB is sufficient to abolish the ability of KCTD11BTB to bind Cul3. Finally, present findings, along with previous literature data, provide a virtually complete coverage of Cul3 binding ability of the members of the entire KCTD family.
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25
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Hanack C, Moroni M, Lima WC, Wende H, Kirchner M, Adelfinger L, Schrenk-Siemens K, Tappe-Theodor A, Wetzel C, Kuich PH, Gassmann M, Roggenkamp D, Bettler B, Lewin GR, Selbach M, Siemens J. GABA blocks pathological but not acute TRPV1 pain signals. Cell 2015; 160:759-770. [PMID: 25679765 DOI: 10.1016/j.cell.2015.01.022] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 11/16/2014] [Accepted: 01/06/2015] [Indexed: 01/01/2023]
Abstract
Sensitization of the capsaicin receptor TRPV1 is central to the initiation of pathological forms of pain, and multiple signaling cascades are known to enhance TRPV1 activity under inflammatory conditions. How might detrimental escalation of TRPV1 activity be counteracted? Using a genetic-proteomic approach, we identify the GABAB1 receptor subunit as bona fide inhibitor of TRPV1 sensitization in the context of diverse inflammatory settings. We find that the endogenous GABAB agonist, GABA, is released from nociceptive nerve terminals, suggesting an autocrine feedback mechanism limiting TRPV1 sensitization. The effect of GABAB on TRPV1 is independent of canonical G protein signaling and rather relies on close juxtaposition of the GABAB1 receptor subunit and TRPV1. Activating the GABAB1 receptor subunit does not attenuate normal functioning of the capsaicin receptor but exclusively reverts its sensitized state. Thus, harnessing this mechanism for anti-pain therapy may prevent adverse effects associated with currently available TRPV1 blockers.
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Affiliation(s)
- Christina Hanack
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany; Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Mirko Moroni
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Wanessa C Lima
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Hagen Wende
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Marieluise Kirchner
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Lisa Adelfinger
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Katrin Schrenk-Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Anke Tappe-Theodor
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
| | - Christiane Wetzel
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - P Henning Kuich
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Martin Gassmann
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Dennis Roggenkamp
- Beiersdorf AG, Research & Development, Unnastrasse 48, 20245 Hamburg, Germany
| | - Bernhard Bettler
- Department of Biomedicine, University of Basel, CH-4056 Basel, Switzerland
| | - Gary R Lewin
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Matthias Selbach
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Jan Siemens
- Department of Pharmacology, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany.
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26
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Raveh A, Turecek R, Bettler B. Mechanisms of fast desensitization of GABA(B) receptor-gated currents. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 73:145-65. [PMID: 25637440 DOI: 10.1016/bs.apha.2014.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GABA(B) receptors (GABA(B)Rs) regulate the excitability of most neurons in the central nervous system by modulating the activity of enzymes and ion channels. In the sustained presence of the neurotransmitter γ-aminobutyric acid, GABA(B)Rs exhibit a time-dependent decrease in the receptor response-a phenomenon referred to as homologous desensitization. Desensitization prevents excessive receptor influences on neuronal activity. Much work focused on the mechanisms of GABA(B)R desensitization that operate at the receptor and control receptor expression at the plasma membrane. Over the past few years, it became apparent that GABA(B)Rs additionally evolved mechanisms for faster desensitization. These mechanisms operate at the G protein rather than at the receptor and inhibit G protein signaling within seconds of agonist exposure. The mechanisms for fast desensitization are ideally suited to regulate receptor-activated ion channel responses, which influence neuronal activity on a faster timescale than effector enzymes. Here, we provide an update on the mechanisms for fast desensitization of GABA(B)R responses and discuss physiological and pathophysiological implications.
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Affiliation(s)
- Adi Raveh
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Basel, Switzerland
| | - Rostislav Turecek
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Basel, Switzerland; Department of Auditory Neuroscience, Institute of Experimental Medicine, ASCR, Prague, Czech Republic
| | - Bernhard Bettler
- Department of Biomedicine, Institute of Physiology, Pharmazentrum, University of Basel, Basel, Switzerland.
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27
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GIRK Channels: A Potential Link Between Learning and Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:239-77. [PMID: 26422987 DOI: 10.1016/bs.irn.2015.05.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The ability of drug-associated cues to reinitiate drug craving and seeking, even after long periods of abstinence, has led to the hypothesis that addiction represents a form of pathological learning, in which drugs of abuse hijack normal learning and memory processes to support long-term addictive behaviors. In this chapter, we review evidence suggesting that G protein-gated inwardly rectifying potassium (GIRK/Kir3) channels are one mechanism through which numerous drugs of abuse can modulate learning and memory processes. We will examine the role of GIRK channels in two forms of experience-dependent long-term changes in neuronal function: homeostatic plasticity and synaptic plasticity. We will also discuss how drug-induced changes in GIRK-mediated signaling can lead to changes that support the development and maintenance of addiction.
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