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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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2
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Belelli D, Riva A, Nutt DJ. Reducing the harms of alcohol: nutritional interventions and functional alcohol alternatives. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 175:241-276. [PMID: 38555118 DOI: 10.1016/bs.irn.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The health risks and harm associated with regular alcohol consumption are well documented. In a recent WHO statement published in The Lancet Public Health alcohol consumption has been estimated to contribute worldwide to 3 million deaths in 2016 while also being responsible for 5·1% of the global burden of disease and injury. The total elimination of alcohol consumption, which has been long imbedded in human culture and society, is not practical and prohibition policies have proved historically ineffective. However, valuable strategies to reduce alcohol harms are already available and improved alternative approaches are currently being developed. Here, we will review and discuss recent advances on two main types of approaches, that is nutritional interventions and functional alcohol alternatives.
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Affiliation(s)
- Delia Belelli
- GABALabs Res. Senior Scientific Consultant, United Kingdom
| | - Antonio Riva
- Roger Williams Institute of Hepatology (Foundation for Liver Research), London; Faculty of Life Sciences & Medicine, King's College London, London
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3
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Cobb-Lewis D, George A, Hu S, Packard K, Song M, Nguyen-Lopez O, Tesone E, Rowden J, Wang J, Opendak M. The lateral habenula integrates age and experience to promote social transitions in developing rats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575446. [PMID: 38260652 PMCID: PMC10802604 DOI: 10.1101/2024.01.12.575446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Social behavior deficits are an early-emerging marker of psychopathology and are linked with early caregiving quality. However, the infant neural substrates linking early care to social development are poorly understood. Here, we focused on the infant lateral habenula (LHb), a highly-conserved brain region at the nexus between forebrain and monoaminergic circuits. Despite its consistent links to adult psychopathology, this brain region has been understudied in development when the brain is most vulnerable to environmental impacts. In a task combining social and threat cues, suppressing LHb principal neurons had opposing effects in infants versus juveniles, suggesting the LHb promotes a developmental switch in social approach behavior under threat. We observed that early caregiving adversity (ECA) disrupts typical growth curves of LHb baseline structure and function, including volume, firing patterns, neuromodulatory receptor expression, and functional connectivity with cortical regions. Further, we observed that suppressing cortical projections to the LHb rescued social approach deficits following ECA, identifying this microcircuit as a substrate for disrupted social behavior. Together, these results identify immediate biomarkers of ECA in the LHb and highlight this region as a site of early social processing and behavior control.
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Affiliation(s)
- Dana Cobb-Lewis
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
| | - Anne George
- Kennedy Krieger Institute, Baltimore MD USA 21205
| | - Shannon Hu
- Kennedy Krieger Institute, Baltimore MD USA 21205
| | | | - Mingyuan Song
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
| | - Oliver Nguyen-Lopez
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
| | - Emily Tesone
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
| | - Jhanay Rowden
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
| | - Julie Wang
- Kennedy Krieger Institute, Baltimore MD USA 21205
| | - Maya Opendak
- Kennedy Krieger Institute, Baltimore MD USA 21205
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore MD USA 21205
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4
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Abukhaled Y, Hatab K, Awadhalla M, Hamdan H. Understanding the genetic mechanisms and cognitive impairments in Down syndrome: towards a holistic approach. J Neurol 2024; 271:87-104. [PMID: 37561187 PMCID: PMC10769995 DOI: 10.1007/s00415-023-11890-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 07/15/2023] [Accepted: 07/17/2023] [Indexed: 08/11/2023]
Abstract
The most common genetic cause of intellectual disability is Down syndrome (DS), trisomy 21. It commonly results from three copies of human chromosome 21 (HC21). There are no mutations or deletions involved in DS. Instead, the phenotype is caused by altered transcription of the genes on HC21. These transcriptional variations are responsible for a myriad of symptoms affecting every organ system. A very debilitating aspect of DS is intellectual disability (ID). Although tremendous advances have been made to try and understand the underlying mechanisms of ID, there is a lack of a unified, holistic view to defining the cause and managing the cognitive impairments. In this literature review, we discuss the mechanisms of neuronal over-inhibition, abnormal morphology, and other genetic factors in contributing to the development of ID in DS patients and to gain a holistic understanding of ID in DS patients. We also highlight potential therapeutic approaches to improve the quality of life of DS patients.
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Affiliation(s)
- Yara Abukhaled
- Department of Physiology and Immunology, College of Medicine, and Health Sciences, Khalifa University, 127788, Abu Dhabi, United Arab Emirates
| | - Kenana Hatab
- Department of Physiology and Immunology, College of Medicine, and Health Sciences, Khalifa University, 127788, Abu Dhabi, United Arab Emirates
| | - Mohammad Awadhalla
- Department of Physiology and Immunology, College of Medicine, and Health Sciences, Khalifa University, 127788, Abu Dhabi, United Arab Emirates
| | - Hamdan Hamdan
- Department of Physiology and Immunology, College of Medicine, and Health Sciences, Khalifa University, 127788, Abu Dhabi, United Arab Emirates.
- Healthcare Engineering Innovation Center (HEIC), Khalifa University, 127788, Abu Dhabi, United Arab Emirates.
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5
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Maffioli E, Nonnis S, Grassi Scalvini F, Negri A, Tedeschi G, Toni M. The Neurotoxic Effect of Environmental Temperature Variation in Adult Zebrafish ( Danio rerio). Int J Mol Sci 2023; 24:15735. [PMID: 37958719 PMCID: PMC10648238 DOI: 10.3390/ijms242115735] [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: 09/07/2023] [Revised: 10/18/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023] Open
Abstract
Neurotoxicity consists of the altered functionality of the nervous system caused by exposure to chemical agents or altered chemical-physical parameters. The neurotoxic effect can be evaluated from the molecular to the behavioural level. The zebrafish Danio rerio is a model organism used in many research fields, including ecotoxicology and neurotoxicology. Recent studies by our research group have demonstrated that the exposure of adult zebrafish to low (18 °C) or high (34 °C) temperatures alters their brain proteome and fish behaviour compared to control (26 °C). These results showed that thermal variation alters the functionality of the nervous system, suggesting a temperature-induced neurotoxic effect. To demonstrate that temperature variation can be counted among the factors that generate neurotoxicity, eight different protein datasets, previously published by our research group, were subjected to new analyses using an integrated proteomic approach by means of the Ingenuity Pathway Analysis (IPA) software (Release December 2022). The datasets consist of brain proteome analyses of wild type adult zebrafish kept at three different temperatures (18 °C, 26 °C, and 34 °C) for 4 days (acute) or 21 days (chronic treatment), and of BDNF+/- and BDNF-/- zebrafish kept at 26 °C or 34 °C for 21 days. The results (a) demonstrate that thermal alterations generate an effect that can be defined as neurotoxic (p value ≤ 0.05, activation Z score ≤ -2 or ≥2), (b) identify 16 proteins that can be used as hallmarks of the neurotoxic processes common to all the treatments applied and (c) provide three protein panels (p value ≤ 0.05) related to 18 °C, 34 °C, and BDNF depletion that can be linked to anxiety-like or boldness behaviour upon these treatments.
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Affiliation(s)
- Elisa Maffioli
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell’Università 6, 26900 Lodi, Italy; (E.M.); (S.N.); (F.G.S.); (A.N.)
| | - Simona Nonnis
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell’Università 6, 26900 Lodi, Italy; (E.M.); (S.N.); (F.G.S.); (A.N.)
- CRC “Innovation for Well-Being and Environment” (I-WE), Università degli Studi di Milano, 20126 Milano, Italy
| | - Francesca Grassi Scalvini
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell’Università 6, 26900 Lodi, Italy; (E.M.); (S.N.); (F.G.S.); (A.N.)
| | - Armando Negri
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell’Università 6, 26900 Lodi, Italy; (E.M.); (S.N.); (F.G.S.); (A.N.)
| | - Gabriella Tedeschi
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell’Università 6, 26900 Lodi, Italy; (E.M.); (S.N.); (F.G.S.); (A.N.)
- CRC “Innovation for Well-Being and Environment” (I-WE), Università degli Studi di Milano, 20126 Milano, Italy
| | - Mattia Toni
- Department of Biology and Biotechnologies “Charles Darwin”, Sapienza University, Via Alfonso Borrelli 50, 00161 Rome, Italy
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Cherubini E, Ben-Ari Y. GABA Signaling: Therapeutic Targets for Neurodegenerative and Neurodevelopmental Disorders. Brain Sci 2023; 13:1240. [PMID: 37759841 PMCID: PMC10526277 DOI: 10.3390/brainsci13091240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 08/24/2023] [Indexed: 09/29/2023] Open
Abstract
This Special Issue, "GABA Signaling: Therapeutic Targets for Neurodegenerative and Neurodevelopmental Disorders", focuses on a fundamental property of the neurotransmitter γ-aminobutyric acid (GABA), namely its capacity to shift, in particular conditions, from the hyperpolarizing to the depolarizing direction [...].
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Affiliation(s)
- Enrico Cherubini
- European Brain Research Institute (EBRI), Rita Levi-Montalcini Foundation, Viale Regina Elena 293-295, 00161 Roma, Italy
| | - Yehezkel Ben-Ari
- Neurochlore, Campus Scientifique de Luminy, 163 Route de Luminy, CEDEX 09, 13288 Marseille, France;
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7
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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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8
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Ueberbach T, Simacek CA, Tegeder I, Kirischuk S, Mittmann T. Tonic activation of GABA B receptors via GAT-3 mediated GABA release reduces network activity in the developing somatosensory cortex in GAD67-GFP mice. Front Synaptic Neurosci 2023; 15:1198159. [PMID: 37325697 PMCID: PMC10267986 DOI: 10.3389/fnsyn.2023.1198159] [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: 03/31/2023] [Accepted: 05/05/2023] [Indexed: 06/17/2023] Open
Abstract
The efficiency of neocortical information processing critically depends on the balance between the glutamatergic (excitatory, E) and GABAergic (inhibitory, I) synaptic transmission. A transient imbalance of the E/I-ratio during early development might lead to neuropsychiatric disorders later in life. The transgenic glutamic acid decarboxylase 67-green fluorescent protein (GAD67-GFP) mouse line (KI) was developed to selectively visualize GABAergic interneurons in the CNS. However, haplodeficiency of the GAD67 enzyme, the main GABA synthetizing enzyme in the brain, temporarily leads to a low GABA level in the developing brain of these animals. However, KI mice did not demonstrate any epileptic activity and only few and mild behavioral deficits. In the present study we investigated how the developing somatosensory cortex of KI-mice compensates the reduced GABA level to prevent brain hyperexcitability. Whole-cell patch clamp recordings from layer 2/3 pyramidal neurons at P14 and at P21 revealed a reduced frequency of miniature inhibitory postsynaptic currents (mIPSCs) in KI mice without any change in amplitude or kinetics. Interestingly, mEPSC frequencies were also decreased, while the E/I-ratio was nevertheless shifted toward excitation. Surprisingly, multi-electrode-recordings (MEA) from acute slices revealed a decreased spontaneous neuronal network activity in KI mice compared to wild-type (WT) littermates, pointing to a compensatory mechanism that prevents hyperexcitability. Blockade of GABAB receptors (GABABRs) with CGP55845 strongly increased the frequency of mEPSCs in KI, but failed to affect mIPSCs in any genotype or age. It also induced a membrane depolarization in P14 KI, but not in P21 KI or WT mice. MEA recordings in presence of CGP55845 revealed comparable levels of network activity in both genotypes, indicating that tonically activated GABABRs balance neuronal activity in P14 KI cortex despite the reduced GABA levels. Blockade of GABA transporter 3 (GAT-3) reproduced the CGP55845 effects suggesting that tonic activation of GABABRs is mediated by ambient GABA released via GAT-3 operating in reverse mode. We conclude that GAT-3-mediated GABA release leads to tonic activation of both pre- and postsynaptic GABABRs and restricts neuronal excitability in the developing cortex to compensate for reduced neuronal GABA synthesis. Since GAT-3 is predominantly located in astrocytes, GAD67 haplodeficiency may potentially stimulate astrocytic GABA synthesis through GAD67-independent pathways.
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Affiliation(s)
- Timo Ueberbach
- Institute for Physiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Clara A. Simacek
- Institute for Physiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Irmgard Tegeder
- Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University, Frankfurt, Germany
| | - Sergei Kirischuk
- Institute for Physiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Thomas Mittmann
- Institute for Physiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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9
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Nino P, Mzia Z, Nadezhda J, Yousef T, Giorgi L, Tamar L. Short- and long-term effects of chronic toluene exposure on spatial memory in adolescent and adult male Wistar rats. Neurosci Lett 2023; 805:137238. [PMID: 37037302 DOI: 10.1016/j.neulet.2023.137238] [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: 02/03/2023] [Revised: 03/12/2023] [Accepted: 04/05/2023] [Indexed: 04/12/2023]
Abstract
Addiction to toluene-containing volatile inhalants is of significant medical and social concern, particularly among youth. These concerns are underscored by the fact that the majority of adult abusers of toluene started as teenagers. Surprisingly, however, the lasting effects of chronic toluene exposure, especially in various age groups, have not been well investigated. Recently, we reported that adolescent and adult male Wistar rats show differential responses to chronic toluene exposure in recognition memory tasks. Since different cognitive functions may be differentially affected by drugs of abuse, we used the same model to evaluate the short- and long-term effects of chronic toluene on spatial learning and memory using Morris water maze. Daily exposure to toluene (2000 ppm) for 40 days (5 min/day) resulted in age-dependent behavioral changes. For example, only adolescent animals showed a decrease in time and distance travelled to find the hidden platform 24 h after the last toluene exposure. In contrast, only adult rats exhibited a decrease in acquisition time and distance travelled at 90 days' post toluene exposure. Our data provide further support for the contention that age-dependent responses should be taken into consideration in interventional attempts to overcome specific detrimental consequences of chronic toluene exposure.
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Affiliation(s)
- Pochkhidze Nino
- School of Natural Sciences and Medicine, Ilia State University. Tbilisi, Georgia; Department of Brain Ultrastructure and Nanoarchitecture, I. Beritashvili Center of Experimental Biomedicine, Tbilisi, Georgia
| | - Zhvania Mzia
- School of Natural Sciences and Medicine, Ilia State University. Tbilisi, Georgia; Department of Brain Ultrastructure and Nanoarchitecture, I. Beritashvili Center of Experimental Biomedicine, Tbilisi, Georgia.
| | - Japaridze Nadezhda
- Department of Brain Ultrastructure and Nanoarchitecture, I. Beritashvili Center of Experimental Biomedicine, Tbilisi, Georgia; Medical School of New Vision University, Tbilisi, Georgia
| | - Tizabi Yousef
- Department of Pharmacology, Howard University College of Medicine, Washington, DC, USA
| | - Lobzhanidze Giorgi
- Department of Brain Ultrastructure and Nanoarchitecture, I. Beritashvili Center of Experimental Biomedicine, Tbilisi, Georgia
| | - Lordkipanidze Tamar
- School of Natural Sciences and Medicine, Ilia State University. Tbilisi, Georgia
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10
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Shpakov AO. Allosteric Regulation of G-Protein-Coupled Receptors: From Diversity of Molecular Mechanisms to Multiple Allosteric Sites and Their Ligands. Int J Mol Sci 2023; 24:6187. [PMID: 37047169 PMCID: PMC10094638 DOI: 10.3390/ijms24076187] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/21/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
Allosteric regulation is critical for the functioning of G protein-coupled receptors (GPCRs) and their signaling pathways. Endogenous allosteric regulators of GPCRs are simple ions, various biomolecules, and protein components of GPCR signaling (G proteins and β-arrestins). The stability and functional activity of GPCR complexes is also due to multicenter allosteric interactions between protomers. The complexity of allosteric effects caused by numerous regulators differing in structure, availability, and mechanisms of action predetermines the multiplicity and different topology of allosteric sites in GPCRs. These sites can be localized in extracellular loops; inside the transmembrane tunnel and in its upper and lower vestibules; in cytoplasmic loops; and on the outer, membrane-contacting surface of the transmembrane domain. They are involved in the regulation of basal and orthosteric agonist-stimulated receptor activity, biased agonism, GPCR-complex formation, and endocytosis. They are targets for a large number of synthetic allosteric regulators and modulators, including those constructed using molecular docking. The review is devoted to the principles and mechanisms of GPCRs allosteric regulation, the multiplicity of allosteric sites and their topology, and the endogenous and synthetic allosteric regulators, including autoantibodies and pepducins. The allosteric regulation of chemokine receptors, proteinase-activated receptors, thyroid-stimulating and luteinizing hormone receptors, and beta-adrenergic receptors are described in more detail.
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Affiliation(s)
- Alexander O Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223 St. Petersburg, Russia
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11
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Isu UH, Badiee SA, Khodadadi E, Moradi M. Cholesterol in Class C GPCRs: Role, Relevance, and Localization. MEMBRANES 2023; 13:301. [PMID: 36984688 PMCID: PMC10056374 DOI: 10.3390/membranes13030301] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
G-protein coupled receptors (GPCRs), one of the largest superfamilies of cell-surface receptors, are heptahelical integral membrane proteins that play critical roles in virtually every organ system. G-protein-coupled receptors operate in membranes rich in cholesterol, with an imbalance in cholesterol level within the vicinity of GPCR transmembrane domains affecting the structure and/or function of many GPCRs, a phenomenon that has been linked to several diseases. These effects of cholesterol could result in indirect changes by altering the mechanical properties of the lipid environment or direct changes by binding to specific sites on the protein. There are a number of studies and reviews on how cholesterol modulates class A GPCRs; however, this area of study is yet to be explored for class C GPCRs, which are characterized by a large extracellular region and often form constitutive dimers. This review highlights specific sites of interaction, functions, and structural dynamics involved in the cholesterol recognition of the class C GPCRs. We summarize recent data from some typical family members to explain the effects of membrane cholesterol on the structural features and functions of class C GPCRs and speculate on their corresponding therapeutic potential.
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12
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GABA A and GABA B Receptors Mediate GABA-Induced Intracellular Ca 2+ Signals in Human Brain Microvascular Endothelial Cells. Cells 2022; 11:cells11233860. [PMID: 36497118 PMCID: PMC9739010 DOI: 10.3390/cells11233860] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/17/2022] [Accepted: 11/28/2022] [Indexed: 12/02/2022] Open
Abstract
Numerous studies recently showed that the inhibitory neurotransmitter, γ-aminobutyric acid (GABA), can stimulate cerebral angiogenesis and promote neurovascular coupling by activating the ionotropic GABAA receptors on cerebrovascular endothelial cells, whereas the endothelial role of the metabotropic GABAB receptors is still unknown. Preliminary evidence showed that GABAA receptor stimulation can induce an increase in endothelial Ca2+ levels, but the underlying signaling pathway remains to be fully unraveled. In the present investigation, we found that GABA evoked a biphasic elevation in [Ca2+]i that was initiated by inositol-1,4,5-trisphosphate- and nicotinic acid adenine dinucleotide phosphate-dependent Ca2+ release from neutral and acidic Ca2+ stores, respectively, and sustained by store-operated Ca2+ entry. GABAA and GABAB receptors were both required to trigger the endothelial Ca2+ response. Unexpectedly, we found that the GABAA receptors signal in a flux-independent manner via the metabotropic GABAB receptors. Likewise, the full Ca2+ response to GABAB receptors requires functional GABAA receptors. This study, therefore, sheds novel light on the molecular mechanisms by which GABA controls endothelial signaling at the neurovascular unit.
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13
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Masoli S, Rizza MF, Tognolina M, Prestori F, D’Angelo E. Computational models of neurotransmission at cerebellar synapses unveil the impact on network computation. Front Comput Neurosci 2022; 16:1006989. [PMID: 36387305 PMCID: PMC9649760 DOI: 10.3389/fncom.2022.1006989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/10/2022] [Indexed: 11/25/2022] Open
Abstract
The neuroscientific field benefits from the conjoint evolution of experimental and computational techniques, allowing for the reconstruction and simulation of complex models of neurons and synapses. Chemical synapses are characterized by presynaptic vesicle cycling, neurotransmitter diffusion, and postsynaptic receptor activation, which eventually lead to postsynaptic currents and subsequent membrane potential changes. These mechanisms have been accurately modeled for different synapses and receptor types (AMPA, NMDA, and GABA) of the cerebellar cortical network, allowing simulation of their impact on computation. Of special relevance is short-term synaptic plasticity, which generates spatiotemporal filtering in local microcircuits and controls burst transmission and information flow through the network. Here, we present how data-driven computational models recapitulate the properties of neurotransmission at cerebellar synapses. The simulation of microcircuit models is starting to reveal how diverse synaptic mechanisms shape the spatiotemporal profiles of circuit activity and computation.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | | | | | - Francesca Prestori
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
- *Correspondence: Francesca Prestori,
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
- IRCCS Mondino Foundation, Brain Connectivity Center, Pavia, Italy
- Egidio D’Angelo,
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Nutt DJ, Tyacke RJ, Spriggs M, Jacoby V, Borthwick AD, Belelli D. Functional Alternatives to Alcohol. Nutrients 2022; 14:nu14183761. [PMID: 36145137 PMCID: PMC9505959 DOI: 10.3390/nu14183761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/06/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
The consumption of alcohol is associated with well-known health harms and many governments worldwide are actively engaged in devising approaches to reduce them. To this end, a common proposed strategy aims at reducing alcohol consumption. This approach has led to the development of non-alcoholic drinks, which have been especially welcome by younger, wealthier, health-conscious consumers, who have been turning away from alcohol to look toward alternatives. However, a drawback of non-alcoholic drinks is that they do not facilitate social interaction in the way alcohol does, which is the main reason behind social drinking. Therefore, an alternative approach is to develop functional drinks that do not use alcohol yet mimic the positive, pro-social effects of alcohol without the associated harms. This article will discuss (1) current knowledge of how alcohol mediates its effects in the brain, both the desirable, e.g., antistress to facilitate social interactions, and the harmful ones, with a specific focus on the pivotal role played by the gamma-aminobutyric acid (GABA) neurotransmitter system and (2) how this knowledge can be exploited to develop functional safe alternatives to alcohol using either molecules already existing in nature or synthetic ones. This discussion will be complemented by an analysis of the regulatory challenges associated with the novel endeavour of bringing safe, functional alternatives to alcohol from the bench to bars.
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