51
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Nguyen QA, Nicoll RA. The GABA A Receptor β Subunit Is Required for Inhibitory Transmission. Neuron 2018; 98:718-725.e3. [PMID: 29706582 DOI: 10.1016/j.neuron.2018.03.046] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 01/24/2018] [Accepted: 03/26/2018] [Indexed: 11/15/2022]
Abstract
While the canonical assembly of a GABAA receptor contains two α subunits, two β subunits, and a fifth subunit, it is unclear which variants of each subunit are necessary for native receptors. We used CRISPR/Cas9 to dissect the role of the GABAA receptor β subunits in inhibitory transmission onto hippocampal CA1 pyramidal cells and found that deletion of all β subunits 1, 2, and 3 completely eliminated inhibitory responses. In addition, only knockout of β3, alone or in combination with another β subunit, impaired inhibitory synaptic transmission. We found that β3 knockout impairs inhibitory input from PV but not SOM expressing interneurons. Furthermore, expression of β3 alone on the background of the β1-3 subunit knockout was sufficient to restore synaptic and extrasynaptic inhibitory transmission. These findings reveal a crucial role for the β3 subunit in inhibitory transmission and identify a synapse-specific role of the β3 subunit in GABAergic synaptic transmission.
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Affiliation(s)
- Quynh-Anh Nguyen
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Roger A Nicoll
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA.
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52
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Leacock S, Syed P, James VM, Bode A, Kawakami K, Keramidas A, Suster M, Lynch JW, Harvey RJ. Structure/Function Studies of the α4 Subunit Reveal Evolutionary Loss of a GlyR Subtype Involved in Startle and Escape Responses. Front Mol Neurosci 2018; 11:23. [PMID: 29445326 PMCID: PMC5797729 DOI: 10.3389/fnmol.2018.00023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/16/2018] [Indexed: 01/08/2023] Open
Abstract
Inhibitory glycine receptors (GlyRs) are pentameric ligand-gated anion channels with major roles in startle disease/hyperekplexia (GlyR α1), cortical neuronal migration/autism spectrum disorder (GlyR α2), and inflammatory pain sensitization/rhythmic breathing (GlyR α3). However, the role of the GlyR α4 subunit has remained enigmatic, because the corresponding human gene (GLRA4) is thought to be a pseudogene due to an in-frame stop codon at position 390 within the fourth membrane-spanning domain (M4). Despite this, a recent genetic study has implicated GLRA4 in intellectual disability, behavioral problems and craniofacial anomalies. Analyzing data from sequenced genomes, we found that GlyR α4 subunit genes are predicted to be intact and functional in the majority of vertebrate species—with the exception of humans. Cloning of human GlyR α4 cDNAs excluded alternative splicing and RNA editing as mechanisms for restoring a full-length GlyR α4 subunit. Moreover, artificial restoration of the missing conserved arginine (R390) in the human cDNA was not sufficient to restore GlyR α4 function. Further bioinformatic and mutagenesis analysis revealed an additional damaging substitution at K59 that ablates human GlyR α4 function, which is not present in other vertebrate GlyR α4 sequences. The substitutions K59 and X390 were also present in the genome of an ancient Denisovan individual, indicating that GLRA4 has been a pseudogene for at least 30,000–50,000 years. In artificial synapses, we found that both mouse and gorilla α4β GlyRs mediate synaptic currents with unusually slow decay kinetics. Lastly, to gain insights into the biological role of GlyR α4 function, we studied the duplicated genes glra4a and glra4b in zebrafish. While glra4b expression is restricted to the retina, using a novel tol2-GAL4FF gene trap line (SAIGFF16B), we found that the zebrafish GlyR α4a subunit gene (glra4a) is strongly expressed in spinal cord and hindbrain commissural neurones. Using gene knockdown and a dominant-negative GlyR α4aR278Q mutant, we found that GlyR α4a contributes to touch-evoked escape behaviors in zebrafish. Thus, although GlyR α4 is unlikely to be involved in human startle responses or disease states, this subtype may contribute to escape behaviors in other organisms.
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Affiliation(s)
- Sophie Leacock
- Department of Pharmacology, UCL School of Pharmacy, London, United Kingdom
| | - Parnayan Syed
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Victoria M James
- Department of Pharmacology, UCL School of Pharmacy, London, United Kingdom
| | - Anna Bode
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics and Department of Genetics, Graduate University for Advanced Studies (SOKENDAI), Mishima, Japan
| | - Angelo Keramidas
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | | | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.,School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Robert J Harvey
- School of Health and Sport Sciences, University of the Sunshine Coast, Sippy Downs, QLD, Australia.,Sunshine Coast Health Institute, Birtinya, QLD, Australia
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53
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Milanos S, Kuenzel K, Gilbert DF, Janzen D, Sasi M, Buettner A, Frimurer TM, Villmann C. Structural changes at the myrtenol backbone reverse its positive allosteric potential into inhibitory GABAA receptor modulation. Biol Chem 2018; 399:549-563. [DOI: 10.1515/hsz-2017-0262] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/24/2018] [Indexed: 02/07/2023]
Abstract
Abstract
GABAA receptors are ligand-gated anion channels that form pentameric arrangements of various subunits. Positive allosteric modulators of GABAA receptors have been reported as being isolated either from plants or synthesized analogs of known GABAA receptor targeting drugs. Recently, we identified monoterpenes, e.g. myrtenol as a positive allosteric modulator at α1β2 GABAA receptors. Here, along with pharmacophore-based virtual screening studies, we demonstrate that scaffold modifications of myrtenol resulted in the loss of modulatory activity. Two independent approaches, fluorescence-based compound analysis and electrophysiological recordings in whole-cell configurations were used for analysis of transfected cells. C-atoms 1 and 2 of the myrtenol backbone were identified as crucial to preserve positive allosteric potential. A modification at C-atom 2 and lack of the hydroxyl group at C-atom 1 exhibited significantly reduced GABAergic currents at α1β2, α1β2γ, α2β3, α2β3γ and α4β3δ receptors. This effect was independent of the γ2 subunit. A sub-screen with side chain length and volume differences at the C-atom 1 identified two compounds that inhibited GABAergic responses but without receptor subtype specificity. Our combined approach of pharmacophore-based virtual screening and functional readouts reveals that side chain modifications of the bridged six-membered ring structure of myrtenol are crucial for its modulatory potential at GABAA receptors.
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Affiliation(s)
- Sinem Milanos
- Institute for Clinical Neurobiology , Julius-Maximilians-Universität Würzburg , Versbacherstr. 5 , D-97078 Würzburg , Germany
- Department of Chemistry and Pharmacy, Food Chemistry, Emil-Fischer-Center , Friedrich-Alexander-Universität Erlangen-Nürnberg , D-90154 Erlangen , Germany
| | - Katharina Kuenzel
- Institute of Medical Biotechnology , Friedrich-Alexander-Universität Erlangen-Nürnberg , D-91052 Erlangen , Germany
| | - Daniel F. Gilbert
- Institute of Medical Biotechnology , Friedrich-Alexander-Universität Erlangen-Nürnberg , D-91052 Erlangen , Germany
| | - Dieter Janzen
- Institute for Clinical Neurobiology , Julius-Maximilians-Universität Würzburg , Versbacherstr. 5 , D-97078 Würzburg , Germany
| | - Manju Sasi
- Institute for Clinical Neurobiology , Julius-Maximilians-Universität Würzburg , Versbacherstr. 5 , D-97078 Würzburg , Germany
| | - Andrea Buettner
- Department of Chemistry and Pharmacy, Food Chemistry, Emil-Fischer-Center , Friedrich-Alexander-Universität Erlangen-Nürnberg , D-90154 Erlangen , Germany
- Department of Sensory Analytics , Fraunhofer-Institute for Process Engineering and Packaging , D-85354 Freising , Germany
| | - Thomas M. Frimurer
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research , University of Copenhagen , Copenhagen , Denmark
| | - Carmen Villmann
- Institute for Clinical Neurobiology , Julius-Maximilians-Universität Würzburg , Versbacherstr. 5 , D-97078 Würzburg , Germany
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54
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Rosas-Arellano A, Tejeda-Guzmán C, Lorca-Ponce E, Palma-Tirado L, Mantellero CA, Rojas P, Missirlis F, Castro MA. Huntington's disease leads to decrease of GABA-A tonic subunits in the D2 neostriatal pathway and their relocalization into the synaptic cleft. Neurobiol Dis 2018; 110:142-153. [DOI: 10.1016/j.nbd.2017.11.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 10/12/2017] [Accepted: 11/27/2017] [Indexed: 01/24/2023] Open
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55
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Zeilhofer HU, Acuña MA, Gingras J, Yévenes GE. Glycine receptors and glycine transporters: targets for novel analgesics? Cell Mol Life Sci 2018; 75:447-465. [PMID: 28791431 PMCID: PMC11105467 DOI: 10.1007/s00018-017-2622-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 07/14/2017] [Accepted: 08/04/2017] [Indexed: 01/29/2023]
Abstract
Glycinergic neurotransmission has long been known for its role in spinal motor control. During the last two decades, additional functions have become increasingly recognized-among them is a critical contribution to spinal pain processing. Studies in rodent pain models provide proof-of-concept evidence that enhancing inhibitory glycinergic neurotransmission reduces chronic pain symptoms. Apparent strategies for pharmacological intervention include positive allosteric modulators of glycine receptors and modulators or inhibitors of the glial and neuronal glycine transporters GlyT1 and GlyT2. These prospects have led to drug discovery efforts in academia and in industry aiming at compounds that target glycinergic neurotransmission with high specificity. Available data show promising analgesic efficacy. Less is currently known about potential unwanted effects but the presence of glycinergic innervation in CNS areas outside the nociceptive system prompts for a careful evaluation not only of motor function, but also of potential respiratory impairment and addictive properties.
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Affiliation(s)
- Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zürich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | | | - Gonzalo E Yévenes
- Department of Physiology, University of Concepción, Concepción, Chile
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56
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Ren H, Guan L, Zhao L, Lin Y, Wang Y, Yang Z, Li X, Ma X, Cheng X, Deng W, Aitchison KJ, Cao L, Li T. Contribution of genes in the GABAergic pathway to bipolar disorder and its executive function deficit in the Chinese Han population. Am J Med Genet B Neuropsychiatr Genet 2018; 177:50-67. [PMID: 29135068 DOI: 10.1002/ajmg.b.32601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 07/30/2017] [Accepted: 09/05/2017] [Indexed: 02/05/2023]
Abstract
In this study, we investigated the association between bipolar I disorder (BDI) and between cognitive deficits therein and SNPs in GABAergic receptor genes. The sample comprised 477 patients with BDI and 438 healthy controls, with three neurocognitive tests being administered in 123 patients and 164 controls. For three SNPs, rs505474, rs1398175, and rs4868029 in the GABRA2, GABRA4, and GABRP genes, respectively, their allele frequencies were significantly different between patients and controls (Bonferroni-adjusted p = values 3.84 × 10-4 , 9.92 × 10-3 , and 1.22 × 10-2 , respectively). Four haplotypes were significantly associated with BDI (TA and AG for rs3815762 and rs4868029 in GABRP, GG for rs11636988 and rs8024256 in GABRB3 and GAGG for rs2197414, rs4921195, rs13188991, and rs11956731 in GABRA6, with p values of 0.0038, 0.044, 0.0176, and 0.0267, respectively, on 10,000 permutations). Furthermore, the SNP (rs2912585) within 250 kb upstream of the GABRB3 gene displayed a strong association with the Tower of Hanoi (TOH) executive time in the patient group (p = 2.844 × 10-6 ). One other SNP (rs754661), which is located at the intronic region of the same gene, was associated with the global trait of the executive function and post hoc analysis showed significant SNP by group effect (p = 0.0094). Our study supports previous findings that GABAA receptor genes are associated with bipolar disorder; it also suggests that the GABAA genes, especially the GABRB3 gene, might play a role in the executive function deficit in bipolar disorder, although future replication with a larger sample size is needed.
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Affiliation(s)
- Hongyan Ren
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China.,Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China.,Psychiatry and Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Lijie Guan
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | - Liansheng Zhao
- Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Yin Lin
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | - Yincheng Wang
- Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Zhenxing Yang
- Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Xuan Li
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | - Xiaohong Ma
- Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
| | - Xiongchao Cheng
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | - Wenhao Deng
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | | | - Liping Cao
- Affiliated Brain Hospital of Guangzhou Medical University, Guangzhou Brain Hospital, Guangzhou, Guangdong, P.R. China
| | - Tao Li
- Psychiatric Laboratory and Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
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57
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Liu L, Yang C, Shen J, Huang L, Lin W, Tang H, Liang W, Shao W, Zhang H, He J. GABRA3 promotes lymphatic metastasis in lung adenocarcinoma by mediating upregulation of matrix metalloproteinases. Oncotarget 2017; 7:32341-50. [PMID: 27081042 PMCID: PMC5078017 DOI: 10.18632/oncotarget.8700] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 03/18/2016] [Indexed: 11/25/2022] Open
Abstract
Tumor metastasis is the main reason for the poor prognosis of lung cancer patients. The GABAA receptor subunit GABRA3 is reportedly upregulated in lung cancer. Herein, we show that high GABRA3 protein expression in lung adenocarcinoma correlated positively with disease stage, lymphatic metastasis status and poor patient survival. In addition, GABRA3 induced MMP-2 and MMP-9 expression through activation of the JNK/AP-1 signaling pathway, which enhanced lymphatic metastasis by lung adenocarcinoma both in vitro and in vivo. These results indicate that GABRA3 promotes lymph node metastasis and may thus be an effective therapeutic target for anticancer treatment.
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Affiliation(s)
- Liping Liu
- The Translational Medicine Laboratory, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Chenglin Yang
- Southern Medical University, Guangzhou, China.,Department of Thoracic Surgery, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jianfei Shen
- Department of Thoracic Surgery, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Liyan Huang
- The Translational Medicine Laboratory, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Weixuan Lin
- The Translational Medicine Laboratory, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Hailing Tang
- The Translational Medicine Laboratory, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Wenhua Liang
- Department of Thoracic Surgery, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Wenlong Shao
- Department of Thoracic Surgery, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Haibo Zhang
- The Translational Medicine Laboratory, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Department of Anesthesia, Medicine and Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jianxing He
- Southern Medical University, Guangzhou, China.,Department of Thoracic Surgery, State Key Laboratory of Respiratory Disease, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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58
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Sahin S, Eulenburg V, Heinlein A, Villmann C, Pischetsrieder M. Identification of eugenol as the major determinant of GABAA-receptor activation by aqueous Syzygium aromaticum L. (clove buds) extract. J Funct Foods 2017. [DOI: 10.1016/j.jff.2017.08.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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59
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Monastrol, a 3,4-dihydropyrimidin-2(1 H )-thione, as structural scaffold for the development of modulators for GHB high-affinity binding sites and α 1 β 2 δ GABA A receptors. Eur J Med Chem 2017; 138:300-312. [DOI: 10.1016/j.ejmech.2017.06.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/19/2017] [Accepted: 06/14/2017] [Indexed: 11/18/2022]
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60
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Towards a Better Understanding of GABAergic Remodeling in Alzheimer's Disease. Int J Mol Sci 2017; 18:ijms18081813. [PMID: 28825683 PMCID: PMC5578199 DOI: 10.3390/ijms18081813] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/16/2017] [Accepted: 08/17/2017] [Indexed: 12/18/2022] Open
Abstract
γ-aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the vertebrate brain. In the past, there has been a major research drive focused on the dysfunction of the glutamatergic and cholinergic neurotransmitter systems in Alzheimer’s disease (AD). However, there is now growing evidence in support of a GABAergic contribution to the pathogenesis of this neurodegenerative disease. Previous studies paint a complex, convoluted and often inconsistent picture of AD-associated GABAergic remodeling. Given the importance of the GABAergic system in neuronal function and homeostasis, in the maintenance of the excitatory/inhibitory balance, and in the processes of learning and memory, such changes in GABAergic function could be an important factor in both early and later stages of AD pathogenesis. Given the limited scope of currently available therapies in modifying the course of the disease, a better understanding of GABAergic remodeling in AD could open up innovative and novel therapeutic opportunities.
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61
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Lindemeyer AK, Shen Y, Yazdani F, Shao XM, Spigelman I, Davies DL, Olsen RW, Liang J. α2 Subunit-Containing GABA A Receptor Subtypes Are Upregulated and Contribute to Alcohol-Induced Functional Plasticity in the Rat Hippocampus. Mol Pharmacol 2017; 92:101-112. [PMID: 28536106 DOI: 10.1124/mol.116.107797] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/05/2017] [Indexed: 12/20/2022] Open
Abstract
Alcohol (EtOH) intoxication causes changes in the rodent brain γ-aminobutyric acid receptor (GABAAR) subunit composition and function, playing a crucial role in EtOH withdrawal symptoms and dependence. Building evidence indicates that withdrawal from acute EtOH and chronic intermittent EtOH (CIE) results in decreased EtOH-enhanced GABAAR δ subunit-containing extrasynaptic and EtOH-insensitive α1βγ2 subtype synaptic GABAARs but increased synaptic α4βγ2 subtype, and increased EtOH sensitivity of GABAAR miniature postsynaptic currents (mIPSCs) correlated with EtOH dependence. Here we demonstrate that after acute EtOH intoxication and CIE, upregulation of hippocampal α4βγ2 subtypes, as well as increased cell-surface levels of GABAAR α2 and γ1 subunits, along with increased α2β1γ1 GABAAR pentamers in hippocampal slices using cell-surface cross-linking, followed by Western blot and coimmunoprecipitation. One-dose and two-dose acute EtOH treatments produced temporal plastic changes in EtOH-induced anxiolysis or withdrawal anxiety, and the presence or absence of EtOH-sensitive synaptic currents correlated with cell surface peptide levels of both α4 and γ1(new α2) subunits. CIE increased the abundance of novel mIPSC patterns differing in activation/deactivation kinetics, charge transfer, and sensitivity to EtOH. The different mIPSC patterns in CIE could be correlated with upregulated highly EtOH-sensitive α2βγ subtypes and EtOH-sensitive α4βγ2 subtypes. Naïve α4 subunit knockout mice express EtOH-sensitive mIPSCs in hippocampal slices, correlating with upregulated GABAAR α2 (and not α4) subunits. Consistent with α2, β1, and γ1 subunits genetically linked to alcoholism in humans, our findings indicate that these new α2-containing synaptic GABAARs could mediate the maintained anxiolytic response to EtOH in dependent individuals, rat or human, contributing to elevated EtOH consumption.
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Affiliation(s)
- A Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Yi Shen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Ferin Yazdani
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Xuesi M Shao
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Igor Spigelman
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Daryl L Davies
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Richard W Olsen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Jing Liang
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
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62
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Zhang Y, Ho TNT, Harvey RJ, Lynch JW, Keramidas A. Structure-Function Analysis of the GlyR α2 Subunit Autism Mutation p.R323L Reveals a Gain-of-Function. Front Mol Neurosci 2017; 10:158. [PMID: 28588452 PMCID: PMC5440463 DOI: 10.3389/fnmol.2017.00158] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/08/2017] [Indexed: 11/17/2022] Open
Abstract
Glycine receptors (GlyRs) containing the α2 subunit regulate cortical interneuron migration. Disruption of the GlyR α2 subunit gene (Glra2) in mice leads to disrupted dorsal cortical progenitor homeostasis, leading to a depletion of projection neurons and moderate microcephaly in newborn mice. In humans, rare variants in GLRA2, which is located on the X chromosome, are associated with autism spectrum disorder (ASD) in the hemizygous state in males. These include a microdeletion (GLRA2∆ex8-9) and missense mutations in GLRA2 (p.N109S and p.R126Q) that impair cell-surface expression of GlyR α2, and either abolish or markedly reduce sensitivity to glycine. We report the functional characterization of a third missense variant in GLRA2 (p.R323L), associated with autism, macrocephaly, epilepsy and hypothyroidism in a female proband. Using heterosynapse and macroscopic current recording techniques, we reveal that GlyR α2R323L exhibits reduced glycine sensitivity, but significantly increased inhibitory postsynaptic current (IPSC) rise and decay times. Site-directed mutagenesis revealed that the nature of the amino acid switch at position 323 is critical for impairment of GlyR function. Single-channel recordings revealed that the conductance of α2R323Lβ channels was higher than α2β channels. Longer mean opening durations induced by p.R323L may be due to a change in the gating pathway that enhances the stability of the GlyR open state. The slower synaptic decay times, longer duration active periods and increase in conductance demonstrates that the GlyR α2 p.R323L mutation results in an overall gain of function, and that GlyR α2 mutations can be pathogenic in the heterozygous state in females.
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Affiliation(s)
- Yan Zhang
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Thi Nhu Thao Ho
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
| | - Robert J Harvey
- Department of Pharmacology, UCL School of PharmacyLondon, United Kingdom
| | - Joseph W Lynch
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia.,School of Biomedical Sciences, The University of QueenslandBrisbane, QLD, Australia
| | - Angelo Keramidas
- Queensland Brain Institute, The University of QueenslandBrisbane, QLD, Australia
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63
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Chaby LE, Zhang L, Liberzon I. The effects of stress in early life and adolescence on posttraumatic stress disorder, depression, and anxiety symptomatology in adulthood. Curr Opin Behav Sci 2017. [DOI: 10.1016/j.cobeha.2017.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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64
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Horzmann KA, Freeman JL. Zebrafish Get Connected: Investigating Neurotransmission Targets and Alterations in Chemical Toxicity. TOXICS 2016; 4:19. [PMID: 28730152 PMCID: PMC5515482 DOI: 10.3390/toxics4030019] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/09/2016] [Indexed: 12/17/2022]
Abstract
Neurotransmission is the basis of neuronal communication and is critical for normal brain development, behavior, learning, and memory. Exposure to drugs and chemicals can alter neurotransmission, often through unknown pathways and mechanisms. The zebrafish (Danio rerio) model system is increasingly being used to study the brain and chemical neurotoxicity. In this review, the major neurotransmitter systems, including glutamate, GABA, dopamine, norepinephrine, serotonin, acetylcholine, histamine, and glutamate are surveyed and pathways of synthesis, transport, metabolism, and action are examined. Differences between human and zebrafish neurochemical pathways are highlighted. We also review techniques for evaluating neurological function, including the measurement of neurotransmitter levels, assessment of gene expression through transcriptomic analysis, and the recording of neurobehavior. Finally examples of chemical toxicity studies evaluating alterations in neurotransmitter systems in the zebrafish model are reviewed.
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Affiliation(s)
| | - Jennifer L. Freeman
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA;
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65
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Labonne JDJ, Graves TD, Shen Y, Jones JR, Kong IK, Layman LC, Kim HG. A microdeletion at Xq22.2 implicates a glycine receptor GLRA4 involved in intellectual disability, behavioral problems and craniofacial anomalies. BMC Neurol 2016; 16:132. [PMID: 27506666 PMCID: PMC4979147 DOI: 10.1186/s12883-016-0642-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 07/20/2016] [Indexed: 12/03/2022] Open
Abstract
Background Among the 21 annotated genes at Xq22.2, PLP1 is the only known gene involved in Xq22.2 microdeletion and microduplication syndromes with intellectual disability. Using an atypical microdeletion, which does not encompass PLP1, we implicate a novel gene GLRA4 involved in intellectual disability, behavioral problems and craniofacial anomalies. Case presentation We report a female patient (DGDP084) with a de novo Xq22.2 microdeletion of at least 110 kb presenting with intellectual disability, motor delay, behavioral problems and craniofacial anomalies. While her phenotypic features such as cognitive impairment and motor delay show overlap with Pelizaeus-Merzbacher disease (PMD) caused by PLP1 mutations at Xq22.2, this gene is not included in our patient’s microdeletion and is not dysregulated by a position effect. Because the microdeletion encompasses only three genes, GLRA4, MORF4L2 and TCEAL1, we investigated their expression levels in various tissues by RT-qPCR and found that all three genes were highly expressed in whole human brain, fetal brain, cerebellum and hippocampus. When we examined the transcript levels of GLRA4, MORF4L2 as well as TCEAL1 in DGDP084′s family, however, only GLRA4 transcripts were reduced in the female patient compared to her healthy mother. This suggests that GLRA4 is the plausible candidate gene for cognitive impairment, behavioral problems and craniofacial anomalies observed in DGDP084. Importantly, glycine receptors mediate inhibitory synaptic transmission in the brain stem as well as the spinal cord, and are known to be involved in syndromic intellectual disability. Conclusion We hypothesize that GLRA4 is involved in intellectual disability, behavioral problems and craniofacial anomalies as the second gene identified for X-linked syndromic intellectual disability at Xq22.2. Additional point mutations or intragenic deletions of GLRA4 as well as functional studies are needed to further validate our hypothesis. Electronic supplementary material The online version of this article (doi:10.1186/s12883-016-0642-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jonathan D J Labonne
- Department of Obstetrics & Gynecology, Section of Reproductive Endocrinology, Infertility & Genetics, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.,Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Tyler D Graves
- Department of Obstetrics & Gynecology, Section of Reproductive Endocrinology, Infertility & Genetics, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Yiping Shen
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | | | - Il-Keun Kong
- Department of Animal Science, Division of Applied Life Science (BK21plus), Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, Gyeongsangnam-do, South Korea
| | - Lawrence C Layman
- Department of Obstetrics & Gynecology, Section of Reproductive Endocrinology, Infertility & Genetics, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.,Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.,Neuroscience Program, Medical College of Georgia, Augusta University, Augusta, GA, 30912, USA
| | - Hyung-Goo Kim
- Department of Obstetrics & Gynecology, Section of Reproductive Endocrinology, Infertility & Genetics, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA. .,Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
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66
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In Silico Prediction of Gamma-Aminobutyric Acid Type-A Receptors Using Novel Machine-Learning-Based SVM and GBDT Approaches. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2375268. [PMID: 27579307 PMCID: PMC4992803 DOI: 10.1155/2016/2375268] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 06/08/2016] [Accepted: 06/19/2016] [Indexed: 11/17/2022]
Abstract
Gamma-aminobutyric acid type-A receptors (GABAARs) belong to multisubunit membrane spanning ligand-gated ion channels (LGICs) which act as the principal mediators of rapid inhibitory synaptic transmission in the human brain. Therefore, the category prediction of GABAARs just from the protein amino acid sequence would be very helpful for the recognition and research of novel receptors. Based on the proteins' physicochemical properties, amino acids composition and position, a GABAAR classifier was first constructed using a 188-dimensional (188D) algorithm at 90% cd-hit identity and compared with pseudo-amino acid composition (PseAAC) and ProtrWeb web-based algorithms for human GABAAR proteins. Then, four classifiers including gradient boosting decision tree (GBDT), random forest (RF), a library for support vector machine (libSVM), and k-nearest neighbor (k-NN) were compared on the dataset at cd-hit 40% low identity. This work obtained the highest correctly classified rate at 96.8% and the highest specificity at 99.29%. But the values of sensitivity, accuracy, and Matthew's correlation coefficient were a little lower than those of PseAAC and ProtrWeb; GBDT and libSVM can make a little better performance than RF and k-NN at the second dataset. In conclusion, a GABAAR classifier was successfully constructed using only the protein sequence information.
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67
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Characterization of the γ-aminobutyric acid signaling system in the zebrafish (Danio rerio Hamilton) central nervous system by reverse transcription-quantitative polymerase chain reaction. Neuroscience 2016; 343:300-321. [PMID: 27453477 DOI: 10.1016/j.neuroscience.2016.07.018] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 11/20/2022]
Abstract
In the vertebrate brain, inhibition is largely mediated by γ-aminobutyric acid (GABA). This neurotransmitter comprises a signaling machinery of GABAA, GABAB receptors, transporters, glutamate decarboxylases (gads) and 4-aminobutyrate aminotransferase (abat), and associated proteins. Chloride is intimately related to GABAA receptor conductance, GABA uptake, and GADs activity. The response of target neurons to GABA stimuli is shaped by chloride-cation co-transporters (CCCs), which strictly control Cl- gradient across plasma membranes. This research profiled the expression of forty genes involved in GABA signaling in the zebrafish (Danio rerio) brain, grouped brain regions and retinas. Primer pairs were developed for reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The mRNA levels of the zebrafish GABA system share similarities with that of mammals, and confirm previous studies in non-mammalian species. Proposed GABAA receptors are α1β2γ2, α1β2δ, α2bβ3γ2, α2bβ3δ, α4β2γ2, α4β2δ, α6bβ2γ2 and α6bβ2δ. Regional brain differences were documented. Retinal hetero- or homomeric ρ-composed GABAA receptors could exist, accompanying α1βyγ2, α1βyδ, α6aβyγ2, α6aβyδ. Expression patterns of α6a and α6b were opposite, with the former being more abundant in retinas, the latter in brains. Given the stoichiometry α6wβyγz, α6a- or α6b-containing receptors likely have different regulatory mechanisms. Different gene isoforms could originate after the rounds of genome duplication during teleost evolution. This research depicts that one isoform is generally more abundantly expressed than the other. Such observations also apply to GABAB receptors, GABA transporters, GABA-related enzymes, CCCs and GABAA receptor-associated proteins, whose presence further strengthens the proof of a GABA system in zebrafish.
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68
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Burgos CF, Yévenes GE, Aguayo LG. Structure and Pharmacologic Modulation of Inhibitory Glycine Receptors. Mol Pharmacol 2016; 90:318-25. [PMID: 27401877 DOI: 10.1124/mol.116.105726] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 07/08/2016] [Indexed: 01/08/2023] Open
Abstract
Glycine receptors (GlyR) are inhibitory Cys-loop ion channels that contribute to the control of excitability along the central nervous system (CNS). GlyR are found in the spinal cord and brain stem, and more recently they were reported in higher regions of the CNS such as the hippocampus and nucleus accumbens. GlyR are involved in motor coordination, respiratory rhythms, pain transmission, and sensory processing, and they are targets for relevant physiologic and pharmacologic modulators. Several studies with protein crystallography and cryoelectron microscopy have shed light on the residues and mechanisms associated with the activation, blockade, and regulation of pentameric Cys-loop ion channels at the atomic level. Initial studies conducted on the extracellular domain of acetylcholine receptors, ion channels from prokaryote homologs-Erwinia chrysanthemi ligand-gated ion channel (ELIC), Gloeobacter violaceus ligand-gated ion channel (GLIC)-and crystallized eukaryotic receptors made it possible to define the overall structure and topology of the Cys-loop receptors. For example, the determination of pentameric GlyR structures bound to glycine and strychnine have contributed to visualizing the structural changes implicated in the transition between the open and closed states of the Cys-loop receptors. In this review, we summarize how the new information obtained in functional, mutagenesis, and structural studies have contributed to a better understanding of the function and regulation of GlyR.
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Affiliation(s)
- Carlos F Burgos
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
| | - Gonzalo E Yévenes
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
| | - Luis G Aguayo
- Laboratory of Neurophysiology (C.F.B., L.G.A.), and Laboratory of Neuropharmacology (G.E.Y.), Department of Physiology, University of Concepción, Concepción, Chile
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69
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Ogino K, Hirata H. Defects of the Glycinergic Synapse in Zebrafish. Front Mol Neurosci 2016; 9:50. [PMID: 27445686 PMCID: PMC4925712 DOI: 10.3389/fnmol.2016.00050] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/13/2016] [Indexed: 12/26/2022] Open
Abstract
Glycine mediates fast inhibitory synaptic transmission. Physiological importance of the glycinergic synapse is well established in the brainstem and the spinal cord. In humans, the loss of glycinergic function in the spinal cord and brainstem leads to hyperekplexia, which is characterized by an excess startle reflex to sudden acoustic or tactile stimulation. In addition, glycinergic synapses in this region are also involved in the regulation of respiration and locomotion, and in the nociceptive processing. The importance of the glycinergic synapse is conserved across vertebrate species. A teleost fish, the zebrafish, offers several advantages as a vertebrate model for research of glycinergic synapse. Mutagenesis screens in zebrafish have isolated two motor defective mutants that have pathogenic mutations in glycinergic synaptic transmission: bandoneon (beo) and shocked (sho). Beo mutants have a loss-of-function mutation of glycine receptor (GlyR) β-subunit b, alternatively, sho mutant is a glycinergic transporter 1 (GlyT1) defective mutant. These mutants are useful animal models for understanding of glycinergic synaptic transmission and for identification of novel therapeutic agents for human diseases arising from defect in glycinergic transmission, such as hyperekplexia or glycine encephalopathy. Recent advances in techniques for genome editing and for imaging and manipulating of a molecule or a physiological process make zebrafish more attractive model. In this review, we describe the glycinergic defective zebrafish mutants and the technical advances in both forward and reverse genetic approaches as well as in vivo visualization and manipulation approaches for the study of the glycinergic synapse in zebrafish.
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Affiliation(s)
- Kazutoyo Ogino
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University Sagamihara, Japan
| | - Hiromi Hirata
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University Sagamihara, Japan
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70
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Shen ML, Wang CH, Chen RYT, Zhou N, Kao ST, Wu DC. Luteolin inhibits GABAA receptors in HEK cells and brain slices. Sci Rep 2016; 6:27695. [PMID: 27292079 PMCID: PMC4904371 DOI: 10.1038/srep27695] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/24/2016] [Indexed: 11/23/2022] Open
Abstract
Modulation of the A type γ-aminobutyric acid receptors (GABAAR) is one of the major drug targets for neurological and psychological diseases. The natural flavonoid compound luteolin (2-(3,4-Dihydroxyphenyl)- 5,7-dihydroxy-4-chromenone) has been reported to have antidepressant, antinociceptive, and anxiolytic-like effects, which possibly involve the mechanisms of modulating GABA signaling. However, as yet detailed studies of the pharmacological effects of luteolin are still lacking, we investigated the effects of luteolin on recombinant and endogenous GABAAR-mediated current responses by electrophysiological approaches. Our results showed that luteolin inhibited GABA-mediated currents and slowed the activation kinetics of recombinant α1β2, α1β2γ2, α5β2, and α5β2γ2 receptors with different degrees of potency and efficacy. The modulatory effect of luteolin was likely dependent on the subunit composition of the receptor complex: the αβ receptors were more sensitive than the αβγ receptors. In hippocampal pyramidal neurons, luteolin significantly reduced the amplitude and slowed the rise time of miniature inhibitory postsynaptic currents (mIPSCs). However, GABAAR-mediated tonic currents were not significantly influenced by luteolin. These data suggested that luteolin has negative modulatory effects on both recombinant and endogenous GABAARs and inhibits phasic rather than tonic inhibition in hippocampus.
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Affiliation(s)
- Mei-Lin Shen
- Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Chen-Hung Wang
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan
| | - Rita Yu-Tzu Chen
- Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Ning Zhou
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Shung-Te Kao
- Graduate Institute of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Dong Chuan Wu
- Graduate Institute of Clinical Medical Science, China Medical University, Taichung, Taiwan.,Translational Medicine Research Center, China Medical University Hospital, Taichung, Taiwan
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71
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Acuña MA, Yévenes GE, Ralvenius WT, Benke D, Di Lio A, Lara CO, Muñoz B, Burgos CF, Moraga-Cid G, Corringer PJ, Zeilhofer HU. Phosphorylation state-dependent modulation of spinal glycine receptors alleviates inflammatory pain. J Clin Invest 2016; 126:2547-60. [PMID: 27270175 DOI: 10.1172/jci83817] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 04/14/2016] [Indexed: 01/10/2023] Open
Abstract
Diminished inhibitory neurotransmission in the superficial dorsal horn of the spinal cord is thought to contribute to chronic pain. In inflammatory pain, reductions in synaptic inhibition occur partially through prostaglandin E2- (PGE2-) and PKA-dependent phosphorylation of a specific subtype of glycine receptors (GlyRs) that contain α3 subunits. Here, we demonstrated that 2,6-di-tert-butylphenol (2,6-DTBP), a nonanesthetic propofol derivative, reverses inflammation-mediated disinhibition through a specific interaction with heteromeric αβGlyRs containing phosphorylated α3 subunits. We expressed mutant GlyRs in HEK293T cells, and electrophysiological analyses of these receptors showed that 2,6-DTBP interacted with a conserved phenylalanine residue in the membrane-associated stretch between transmembrane regions 3 and 4 of the GlyR α3 subunit. In native murine spinal cord tissue, 2,6-DTBP modulated synaptic, presumably αβ heteromeric, GlyRs only after priming with PGE2. This observation is consistent with results obtained from molecular modeling of the α-β subunit interface and suggests that in α3βGlyRs, the binding site is accessible to 2,6-DTBP only after PKA-dependent phosphorylation. In murine models of inflammatory pain, 2,6-DTBP reduced inflammatory hyperalgesia in an α3GlyR-dependent manner. Together, our data thus establish that selective potentiation of GlyR function is a promising strategy against chronic inflammatory pain and that, to our knowledge, 2,6-DTBP has a unique pharmacological profile that favors an interaction with GlyRs that have been primed by peripheral inflammation.
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72
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Khom S, Hintersteiner J, Luger D, Haider M, Pototschnig G, Mihovilovic MD, Schwarzer C, Hering S. Analysis of β-Subunit-dependent GABAA Receptor Modulation and Behavioral Effects of Valerenic Acid Derivatives. J Pharmacol Exp Ther 2016; 357:580-90. [PMID: 27190170 PMCID: PMC4885513 DOI: 10.1124/jpet.116.232983] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/06/2016] [Indexed: 12/30/2022] Open
Abstract
Valerenic acid (VA)-a β2/3-selective GABA type A (GABAA) receptor modulator-displays anxiolytic and anticonvulsive effects in mice devoid of sedation, making VA an interesting drug candidate. Here we analyzed β-subunit-dependent enhancement of GABA-induced chloride currents (IGABA) by a library of VA derivatives and studied their effects on pentylenetetrazole (PTZ)-induced seizure threshold and locomotion. Compound-induced IGABA enhancement was determined in oocytes expressing α1β1γ2S, α1β2γ2S, or α1β3γ2S receptors. Effects on seizure threshold and locomotion were studied using C57BL/6N mice and compared with saline-treated controls. β2/3-selective VA derivatives such as VA-amide (VA-A) modulating α1β3γ2S (VA-A: Emax = 972 ± 69%, n = 6, P < 0.05) and α1β2γ2S receptors (Emax = 1119 ± 72%, n = 6, P < 0.05) more efficaciously than VA (α1β3γ2S: VA: Emax = 632 ± 88%, n = 9 versus α1β2γ2S: VA: Emax = 721 ± 68%, n = 6) displayed significantly more pronounced seizure threshold elevation than VA (saline control: 40.4 ± 1.4 mg/kg PTZ versus VA 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ versus VA-A 3 mg/kg: 57.9 ± 1.9 mg/kg PTZ, P < 0.05). Similarly, VA's methylamide (VA-MA) enhancing IGABA through β3-containing receptors more efficaciously than VA (Emax = 1043 ± 57%, P < 0.01, n = 6) displayed stronger anticonvulsive effects. Increased potency of IGABA enhancement and anticonvulsive effects at lower doses compared with VA were observed for VA-tetrazole (α1β3γ2S: VA-TET: EC50 = 6.0 ± 1.0 μM, P < 0.05; VA-TET: 0.3 mg/kg: 47.3 ± 0.5 mg/kg PTZ versus VA: 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ, P < 0.05). At higher doses (≥10 mg/kg), VA-A, VA-MA, and VA-TET reduced locomotion. In contrast, unselective VA derivatives induced anticonvulsive effects only at high doses (30 mg/kg) or did not display any behavioral effects. Our data indicate that the β2/3-selective compounds VA-A, VA-MA, and VA-TET induce anticonvulsive effects at low doses (≤10 mg/kg), whereas impairment of locomotion was observed at doses ≥10 mg/kg.
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Affiliation(s)
- S Khom
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - J Hintersteiner
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - D Luger
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - M Haider
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - G Pototschnig
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - M D Mihovilovic
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - C Schwarzer
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - S Hering
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
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73
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Bar-Shira O, Maor R, Chechik G. Gene Expression Switching of Receptor Subunits in Human Brain Development. PLoS Comput Biol 2015; 11:e1004559. [PMID: 26636753 PMCID: PMC4670163 DOI: 10.1371/journal.pcbi.1004559] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 09/15/2015] [Indexed: 01/09/2023] Open
Abstract
Synaptic receptors in the human brain consist of multiple protein subunits, many of which have multiple variants, coded by different genes, and are differentially expressed across brain regions and developmental stages. The brain can tune the electrophysiological properties of synapses to regulate plasticity and information processing by switching from one protein variant to another. Such condition-dependent variant switch during development has been demonstrated in several neurotransmitter systems including NMDA and GABA. Here we systematically detect pairs of receptor-subunit variants that switch during the lifetime of the human brain by analyzing postmortem expression data collected in a population of donors at various ages and brain regions measured using microarray and RNA-seq. To further detect variant pairs that co-vary across subjects, we present a method to quantify age-corrected expression correlation in face of strong temporal trends. This is achieved by computing the correlations in the residual expression beyond a cubic-spline model of the population temporal trend, and can be seen as a nonlinear version of partial correlations. Using these methods, we detect multiple new pairs of context dependent variants. For instance, we find a switch from GLRA2 to GLRA3 that differs from the known switch in the rat. We also detect an early switch from HTR1A to HTR5A whose trends are negatively correlated and find that their age-corrected expression is strongly positively correlated. Finally, we observe that GRIN2B switch to GRIN2A occurs mostly during embryonic development, presumably earlier than observed in rodents. These results provide a systematic map of developmental switching in the neurotransmitter systems of the human brain. Synapses change their properties during development affecting information processing and learning. Most synaptic receptors consist of several proteins, each having several variants coded by closely related genes. These protein variants are similar in structure, yet often differ slightly in their biophysical attributes. Switching a synapse from using one variant to another provides the brain with a way to fine-tune electrophysiological properties of synapses and has been described in NMDA and GABA receptors. Here we describe a systematic approach to detect pairs of context-dependent variants at a genome-wide scale based on a set of post-mortem expression measurements taken from brains at multiple ages. We take into account both the profile of expression as it changes along life and also the detrended age-corrected correlation among genes. This method characterizes the landscape of developmental switches in brain transcriptome, putting forward new candidates pairs for deeper analysis. The abundance of switching between context-dependent variants through life suggests that it is a major mechanism by which the brain tunes its plasticity and information processing.
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Affiliation(s)
- Ossnat Bar-Shira
- Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Ronnie Maor
- Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
| | - Gal Chechik
- Gonda Brain Research Center, Bar-Ilan University, Ramat Gan, Israel
- * E-mail:
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74
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Gong P, Hong H, Perkins EJ. Ionotropic GABA receptor antagonism-induced adverse outcome pathways for potential neurotoxicity biomarkers. Biomark Med 2015; 9:1225-39. [PMID: 26508561 DOI: 10.2217/bmm.15.58] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Antagonism of ionotropic GABA receptors (iGABARs) can occur at three distinct types of receptor binding sites causing chemically induced epileptic seizures. Here we review three adverse outcome pathways, each characterized by a specific molecular initiating event where an antagonist competitively binds to active sites, negatively modulates allosteric sites or noncompetitively blocks ion channel on the iGABAR. This leads to decreased chloride conductance, followed by depolarization of affected neurons, epilepsy-related death and ultimately decreased population. Supporting evidence for causal linkages from the molecular to population levels is presented and differential sensitivity to iGABAR antagonists in different GABA receptors and organisms discussed. Adverse outcome pathways are poised to become important tools for linking mechanism-based biomarkers to regulated outcomes in next-generation risk assessment.
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Affiliation(s)
- Ping Gong
- Environmental Laboratory, US Army Engineer Research & Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA
| | - Huixiao Hong
- Division of Bioinformatics & Biostatistics, National Center for Toxicological Research, US Food & Drug Administration, 3900 NCTR Road, Jefferson, AR 72079, USA
| | - Edward J Perkins
- Environmental Laboratory, US Army Engineer Research & Development Center, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA
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Luger D, Poli G, Wieder M, Stadler M, Ke S, Ernst M, Hohaus A, Linder T, Seidel T, Langer T, Khom S, Hering S. Identification of the putative binding pocket of valerenic acid on GABAA receptors using docking studies and site-directed mutagenesis. Br J Pharmacol 2015; 172:5403-13. [PMID: 26375408 PMCID: PMC4988470 DOI: 10.1111/bph.13329] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 08/25/2015] [Accepted: 08/30/2015] [Indexed: 12/15/2022] Open
Abstract
Background and Purpose β2/3‐subunit‐selective modulation of GABAA receptors by valerenic acid (VA) is determined by the presence of transmembrane residue β2/3N265. Currently, it is not known whether β2/3N265 is part of VA's binding pocket or is involved in the transduction pathway of VA's action. The aim of this study was to clarify the localization of VA's binding pocket on GABAA receptors. Experimental Approach Docking and a structure‐based three‐dimensional pharmacophore were employed to identify candidate amino acid residues that are likely to interact with VA. Selected amino acid residues were mutated, and VA‐induced modulation of the resulting GABAA receptors expressed in Xenopus oocytes was analysed. Key Results A binding pocket for VA at the β+/α− interface encompassing amino acid β3N265 was predicted. Mutational analysis of suggested amino acid residues revealed a complete loss of VA's activity on β3M286W channels as well as significantly decreased efficacy and potency of VA on β3N265S and β3F289S receptors. In addition, reduced efficacy of VA‐induced IGABA enhancement was also observed for α1M235W, β3R269A and β3M286A constructs. Conclusions and Implications Our data suggest that amino acid residues β3N265, β3F289, β3M286, β3R269 in the β3 subunit, at or near the etomidate/propofol binding site(s), form part of a VA binding pocket. The identification of the binding pocket for VA is essential for elucidating its pharmacological effects and might also help to develop new selective GABAA receptor ligands.
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Affiliation(s)
- D Luger
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - G Poli
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | - M Wieder
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - M Stadler
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - S Ke
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - M Ernst
- Department of Molecular Neurosciences, Center of Brain Research, Medical University of Vienna, Vienna, Austria
| | - A Hohaus
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - T Linder
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - T Seidel
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - T Langer
- Department of Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - S Khom
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
| | - S Hering
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria
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76
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Advances in the pharmacology of lGICs auxiliary subunits. Pharmacol Res 2015; 101:65-73. [PMID: 26255765 DOI: 10.1016/j.phrs.2015.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/25/2015] [Accepted: 07/26/2015] [Indexed: 11/21/2022]
Abstract
Ligand-gated ion channels (LGICs) are cell surface integral proteins that mediate the fast neurotransmission in the nervous system. LGICs require auxiliary subunits for their trafficking, assembly and pharmacological modulation. Auxiliary subunits do not form functional homomeric receptors, but are reported to assemble with the principal subunits in order to modulate their pharmacological profiles. For example, nACh receptors are built at least by co-assemble of α and β subunits, and the neuronal auxiliary subunits β3 and α5 and muscle type β, δ, γ, and ϵ determine the agonist affinity of these receptors. Serotonergic 5-HT3B, 5-HT3C, 5-HT3D and 5-HT3E are reported to assemble with the 5-HT3A subunit to modulate its pharmacological profile. Functional studies evaluating the role of γ2 and δ auxiliary subunits of GABAA receptors have made important advances in the understanding of the action of benzodiazepines, ethanol and neurosteroids. Glycine receptors are composed principally by α1-3 subunits and the auxiliary subunit β determines their synaptic location and their pharmacological response to propofol and ethanol. NMDA receptors appear to be functional as heterotetrameric channels. So far, the existence of NMDA auxiliary subunits is controversial. On the other hand, Kainate receptors are modulated by NETO 1 and 2. AMPA receptors are modulated by TARPs, Shisa 9, CKAMP44, CNIH2-3 auxiliary proteins reported that controls their trafficking, conductance and gating of channels. P2X receptors are able to associate with auxiliary Pannexin-1 protein to modulate P2X7 receptors. Considering the pharmacological relevance of different LGICs auxiliary subunits in the present work we will highlight the therapeutic potential of these modulator proteins.
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77
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MacKenzie G, Maguire J. Neurosteroids and GABAergic signaling in health and disease. Biomol Concepts 2015; 4:29-42. [PMID: 25436563 DOI: 10.1515/bmc-2012-0033] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 10/12/2012] [Indexed: 11/15/2022] Open
Abstract
Endogenous neurosteroids such as allopregnanolone, allotetrahydrodeoxycorticosterone, and androstanediol are synthesized either de novo in the brain from cholesterol or are generated from the local metabolism of peripherally derived progesterone or corticosterone. Fluctuations in neurosteroid concentrations are important in the regulation of a number of physiological responses including anxiety and stress, reproductive, and sexual behaviors. These effects are mediated in part by the direct binding of neurosteroids to γ-aminobutyric acid type-A receptors (GABAARs), resulting in the potentiation of GABAAR-mediated currents. Extrasynaptic GABAARs containing the δ subunit, which contribute to the tonic conductance, are particularly sensitive to low nanomolar concentrations of neurosteroids and are likely their preferential target. Considering the large charge transfer generated by these persistently open channels, even subtle changes in neurosteroid concentrations can have a major impact on neuronal excitability. Consequently, aberrant levels of neurosteroids have been implicated in numerous disorders, including, but not limited to, anxiety, neurodegenerative diseases, alcohol abuse, epilepsy, and depression. Here we review the modulation of GABAAR by neurosteroids and the consequences for health and disease.
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78
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Thiel U, Platt SJ, Wolf S, Hatt H, Gisselmann G. Identification of amino acids involved in histamine potentiation of GABA A receptors. Front Pharmacol 2015; 6:106. [PMID: 26074818 PMCID: PMC4443022 DOI: 10.3389/fphar.2015.00106] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/01/2015] [Indexed: 12/13/2022] Open
Abstract
Histamine is a neurotransmitter involved in a number of physiological and neuronal functions. In mammals, such as humans, and rodents, the histaminergic neurons found in the tuberomamillary nucleus project widely throughout the central nervous system. Histamine acts as positive modulator of GABAA receptors (GABAARs) and, in high concentrations (10 mM), as negative modulator of the strychnine-sensitive glycine receptor. However, the exact molecular mechanisms by which histamine acts on GABAARs are unknown. In our study, we aimed to identify amino acids potentially involved in the modulatory effect of histamine on GABAARs. We expressed GABAARs with 12 different point mutations in Xenopus laevis oocytes and characterized the effect of histamine on GABA-induced currents using the two-electrode voltage clamp technique. Our data demonstrate that the amino acid residues β2(N265) and β2(M286), which are important for modulation by propofol, are not involved in the action of histamine. However, we found that histamine modulation is dependent on the amino acid residues α1(R120), β2(Y157), β2(D163), β3(V175), and β3(Q185). We showed that the amino acid residues β2(Y157) and β3(Q185) mediate the positive modulatory effect of histamine on GABA-induced currents, whereas α1(R120) and β2(D163) form a potential histamine interaction site in GABAARs.
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Affiliation(s)
- Ulrike Thiel
- Department of Cell Physiology, Ruhr University Bochum Bochum, Germany
| | - Sarah J Platt
- Department of Cell Physiology, Ruhr University Bochum Bochum, Germany
| | - Steffen Wolf
- Department of Biophysics, Ruhr University Bochum Bochum, Germany ; Department of Biophysics, Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences Shanghai, China
| | - Hanns Hatt
- Department of Cell Physiology, Ruhr University Bochum Bochum, Germany
| | - Günter Gisselmann
- Department of Cell Physiology, Ruhr University Bochum Bochum, Germany
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79
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Jiao D, Liu Y, Li X, Liu J, Zhao M. The role of the GABA system in amphetamine-type stimulant use disorders. Front Cell Neurosci 2015; 9:162. [PMID: 25999814 PMCID: PMC4419710 DOI: 10.3389/fncel.2015.00162] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/13/2015] [Indexed: 11/22/2022] Open
Abstract
Abuse of amphetamine-type stimulants (ATS) has become a global public health problem. ATS causes severe neurotoxicity, which could lead to addiction and could induce psychotic disorders or cognitive dysfunctions. However, until now, there has been a lack of effective medicines for treating ATS-related problems. Findings from recent studies indicate that in addition to the traditional dopamine-ergic system, the GABA (gamma-aminobutyric acid)-ergic system plays an important role in ATS abuse. However, the exact mechanisms of the GABA-ergic system in amphetamine-type stimulant use disorders are not fully understood. This review discusses the role of the GABA-ergic system in ATS use disorders, including ATS induced psychotic disorders and cognitive dysfunctions. We conclude that the GABA-ergic system are importantly involved in the development of ATS use disorders through multiple pathways, and that therapies or medicines that target specific members of the GABA-ergic system may be novel effective interventions for the treatment of ATS use disorders.
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Affiliation(s)
- Dongliang Jiao
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Yao Liu
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
| | - Xiaohong Li
- Department of Neurochemistry, NY State Institute for Basic Research in Developmental Disabilities New York, NY, USA
| | - Jinggen Liu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences Shanghai, China
| | - Min Zhao
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine Shanghai, China
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80
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Zheng N, Cheng J, Zhang W, Li W, Shao X, Xu Z, Xu X, Li Z. Binding difference of fipronil with GABAARs in fruitfly and zebrafish: insights from homology modeling, docking, and molecular dynamics simulation studies. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:10646-10653. [PMID: 25302733 DOI: 10.1021/jf503851z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fipronil, which targets GABAA receptors (GABAARs), is the first phenylpyrazole insecticide widely used in crop protection and public hygiene. However, its high toxicity on fishes greatly limited its applications. In the present study, a series of computational methods including homology modeling, docking, and molecular dynamics simulation studies were integrated to explore the binding difference of fipronil with GABAARs from fruitfly and zebrafish systems. It was found that, in the zebrafish system, the H-bond between 6'Thr and fipronil exerted key effects on the recognition of fipronil, which was absent in the fruitfly system. On the other hand, in the fruitfly system, strong electrostatic interaction between 2'Ala and fipronil was favorable to the binding of fipronil but detrimental to the binding in the zebrafish system. These findings marked the binding difference of fipronil with different GABAARs, which might be helpful in designing selective insecticides against pests instead of fishes.
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Affiliation(s)
- Nan Zheng
- Shanghai Key Laboratory of Chemical Biology and ‡Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology , Shanghai 200237, China
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81
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Abstract
Addiction to MOP-r agonists such as heroin (and also addiction to prescription opioids) has reemerged as an epidemic in the twenty first century, causing massive morbidity. Understanding the genetics contributing to susceptibility to this disease is crucial for the identification of novel therapeutic targets, and also for discovery of genetic markers which would indicate relative protection or vulnerability from addiction, and relative responsiveness to pharmacotherapy. This information could thus eventually inform clinical practice. In this review, we focus primarily on association studies of heroin and opiate addiction, and further describe the studies which have been replicated in this field, and are thus more likely to be useful for translational efforts.
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Affiliation(s)
- Brian Reed
- The Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
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82
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Blankenburg S, Balfanz S, Hayashi Y, Shigenobu S, Miura T, Baumann O, Baumann A, Blenau W. Cockroach GABAB receptor subtypes: molecular characterization, pharmacological properties and tissue distribution. Neuropharmacology 2014; 88:134-44. [PMID: 25242738 DOI: 10.1016/j.neuropharm.2014.08.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 08/10/2014] [Accepted: 08/23/2014] [Indexed: 11/29/2022]
Abstract
γ-aminobutyric acid (GABA) is the predominant inhibitory neurotransmitter in the central nervous system (CNS). Its effects are mediated by either ionotropic GABAA receptors or metabotropic GABAB receptors. GABAB receptors regulate, via Gi/o G-proteins, ion channels, and adenylyl cyclases. In humans, GABAB receptor subtypes are involved in the etiology of neurologic and psychiatric disorders. In arthropods, however, these members of the G-protein-coupled receptor family are only inadequately characterized. Interestingly, physiological data have revealed important functions of GABAB receptors in the American cockroach, Periplaneta americana. We have cloned cDNAs coding for putative GABAB receptor subtypes 1 and 2 of P. americana (PeaGB1 and PeaGB2). When both receptor proteins are co-expressed in mammalian cells, activation of the receptor heteromer with GABA leads to a dose-dependent decrease in cAMP production. The pharmacological profile differs from that of mammalian and Drosophila GABAB receptors. Western blot analyses with polyclonal antibodies have revealed the expression of PeaGB1 and PeaGB2 in the CNS of the American cockroach. In addition to the widespread distribution in the brain, PeaGB1 is expressed in salivary glands and male accessory glands. Notably, PeaGB1-like immunoreactivity has been detected in the GABAergic salivary neuron 2, suggesting that GABAB receptors act as autoreceptors in this neuron.
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Affiliation(s)
- S Blankenburg
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
| | - S Balfanz
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Research Center Jülich, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - Y Hayashi
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | - S Shigenobu
- NIBB Core Research Facilities, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, 444-8585, Japan.
| | - T Miura
- Laboratory of Ecological Genetics, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido, 060-0810, Japan.
| | - O Baumann
- Institute of Biochemistry and Biology, Department of Animal Physiology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany.
| | - A Baumann
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Research Center Jülich, Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - W Blenau
- Institut für Bienenkunde, Polytechnische Gesellschaft, Goethe-Universität Frankfurt am Main, FB Biowissenschaften, Karl-von-Frisch-Weg 2, 61440, Oberursel, Germany.
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83
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Zhang X, Du Z, Liu J, He J. Γ-aminobutyric acid receptors affect the progression and migration of tumor cells. J Recept Signal Transduct Res 2014; 34:431-9. [DOI: 10.3109/10799893.2013.856918] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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84
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Strommer B, Khom S, Kastenberger I, Cicek SS, Stuppner H, Schwarzer C, Hering S. A cycloartane glycoside derived from Actaea racemosa L. modulates GABAA receptors and induces pronounced sedation in mice. J Pharmacol Exp Ther 2014; 351:234-42. [PMID: 25161170 DOI: 10.1124/jpet.114.218024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
23-O-Acetylshengmanol 3-O-β-D-xylopyranoside (Ac-SM) isolated from Actaea racemosa L.-an herbal remedy for the treatment of mild menopausal disorders-has been recently identified as a novel efficacious modulator of GABAA receptors composed of α1-, β2-, and γ2S-subunits. In the present study, we analyzed a potential subunit-selective modulation of GABA-induced chloride currents (IGABA) at GABA concentrations eliciting 3-8% of the maximal GABA response (EC3-8) through nine GABAA receptor isoforms expressed in Xenopus laevis oocytes by Ac-SM with two-microelectrode voltage clamp and behavioral effects 30 minutes after intraperitoneal application in a mouse model. Efficacy of IGABA enhancement by Ac-SM displayed a mild α-subunit dependence with α2β2γ2S (maximal IGABA potentiation [Emax] = 1454 ± 97%) and α5β2γ2S (Emax = 1408 ± 87%) receptors being most efficaciously modulated, followed by slightly weaker IGABA enhancement through α1β2γ2S (Emax = 1187 ± 166%), α3β2γ2S (Emax = 1174 ± 218%), and α6β2γ2S (Emax = 1171 ± 274%) receptors and less pronounced effects on receptors composed of α4β2γ2S (Emax = 752 ± 53%) subunits, whereas potency was not affected by the subunit composition (EC50 values ranging from α1β2γ2S = 35.4 ± 12.3 µM to α5β2γ2S = 50.9 ± 11.8 µM). Replacing β2- with β1- or β3-subunits as well as omitting the γ2S-subunit affected neither efficacy nor potency of IGABA enhancement by Ac-SM. Ac-SM shifted the GABA concentration-response curve toward higher GABA sensitivity (about 3-fold) and significantly increased the maximal GABA response by 44 ± 13%, indicating a pharmacological profile distinct from a pure allosteric GABAA receptor modulator. In mice, Ac-SM significantly reduced anxiety-related behavior in the elevated plus maze test at a dose of 0.6 mg/kg, total ambulation in the open field test at doses ≥6 mg/kg, stress-induced hyperthermia at doses ≥0.6 mg/kg, and significantly elevated seizure threshold at doses ≥20 mg/kg body weight. High efficacy and long biologic half-life of Ac-SM suggest that potential cumulative sedative side effects upon repetitive intake of A. racemosa L. preparations might not be negligible.
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Affiliation(s)
- Barbara Strommer
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Sophia Khom
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Iris Kastenberger
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Serhat Sezai Cicek
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Hermann Stuppner
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Christoph Schwarzer
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (B.S., S.K., S.H.); Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria (I.K., C.S.); and Institute of Pharmacy/Pharmacognosy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria (S.S.C., H.S.)
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85
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Altered expression of δGABAA receptors in health and disease. Neuropharmacology 2014; 88:24-35. [PMID: 25128850 DOI: 10.1016/j.neuropharm.2014.08.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/28/2014] [Accepted: 08/03/2014] [Indexed: 01/08/2023]
Abstract
γ-Aminobutyric acid type A receptors that contain the δ subunit (δGABAA receptors) are expressed in multiple types of neurons throughout the central nervous system, where they generate a tonic conductance that shapes neuronal excitability and synaptic plasticity. These receptors regulate a variety of important behavioral functions, including memory, nociception and anxiety, and may also modulate neurogenesis. Given their functional significance, δGABAA receptors are considered to be novel therapeutic targets for the treatment of memory dysfunction, pain, insomnia and mood disorders. These receptors are highly responsive to sedative-hypnotic drugs, general anesthetics and neuroactive steroids. A further remarkable feature of δGABAA receptors is that their expression levels are highly dynamic and fluctuate substantially during development and in response to physiological changes including stress and the reproductive cycle. Furthermore, the expression of these receptors varies in pathological conditions such as alcoholism, fragile X syndrome, epilepsy, depression, schizophrenia, mood disorders and traumatic brain injury. Such fluctuations in receptor expression have significant consequences for behavior and may alter responsiveness to therapeutic drugs. This review considers the alterations in the expression of δGABAA receptors associated with various states of health and disease and the implications of these changes.
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86
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Schöffmann A, Wimmer L, Goldmann D, Khom S, Hintersteiner J, Baburin I, Schwarz T, Hintersteininger M, Pakfeifer P, Oufir M, Hamburger M, Erker T, Ecker GF, Mihovilovic MD, Hering S. Efficient modulation of γ-aminobutyric acid type A receptors by piperine derivatives. J Med Chem 2014; 57:5602-19. [PMID: 24905252 PMCID: PMC4106271 DOI: 10.1021/jm5002277] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Piperine activates TRPV1 (transient receptor potential vanilloid type 1 receptor) receptors and modulates γ-aminobutyric acid type A receptors (GABAAR). We have synthesized a library of 76 piperine analogues and analyzed their effects on GABAAR by means of a two-microelectrode voltage-clamp technique. GABAAR were expressed in Xenopus laevis oocytes. Structure-activity relationships (SARs) were established to identify structural elements essential for efficiency and potency. Efficiency of piperine derivatives was significantly increased by exchanging the piperidine moiety with either N,N-dipropyl, N,N-diisopropyl, N,N-dibutyl, p-methylpiperidine, or N,N-bis(trifluoroethyl) groups. Potency was enhanced by replacing the piperidine moiety by N,N-dibutyl, N,N-diisobutyl, or N,N-bistrifluoroethyl groups. Linker modifications did not substantially enhance the effect on GABAAR. Compound 23 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dipropyl-2,4-pentadienamide] induced the strongest modulation of GABAA (maximal GABA-induced chloride current modulation (IGABA-max = 1673% ± 146%, EC50 = 51.7 ± 9.5 μM), while 25 [(2E,4E)-5-(1,3-benzodioxol-5-yl)-N,N-dibutyl-2,4-pentadienamide] displayed the highest potency (EC50 = 13.8 ± 1.8 μM, IGABA-max = 760% ± 47%). Compound 23 induced significantly stronger anxiolysis in mice than piperine and thus may serve as a starting point for developing novel GABAAR modulators.
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Affiliation(s)
- Angela Schöffmann
- Department of Pharmacology and Toxicology and §Division of Drug Design and Medicinal Chemistry, Department of Pharmaceutical Chemistry, University of Vienna , Althanstrasse 14, A-1090 Vienna, Austria
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Hung CC, Chen PL, Huang WM, Tai JJ, Hsieh TJ, Ding ST, Hsieh YW, Liou HH. Gene-wide tagging study of the effects of common genetic polymorphisms in the α subunits of the GABA(A) receptor on epilepsy treatment response. Pharmacogenomics 2014; 14:1849-56. [PMID: 24236484 DOI: 10.2217/pgs.13.158] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM We aimed to identify the effect of SNPs in the α-subunits of GABAA receptors on epilepsy treatment outcomes by using a gene-wide tagging method. MATERIALS & METHODS There were 720 epileptic patients included in the present study. A total of 136 tagging SNPs in GABRA1, GABRA2, GABRA3, GABRA4, GABRA5 and GABRA6 were genotyped by Illumina(®)GoldenGate(®) Genotyping platform. Clinical information, such as prescribed antiepileptic drugs, height, weight, epilepsy syndrome classification, etiology, number of attacks, renal function and liver function were collected. The associations between SNPs and epilepsy treatment outcomes were analyzed using SAS(®) version 9.1.3. Both multivariate logistic regression and multifactor dimensionality reduction analyses were performed. RESULTS The results of single gene effects did not remain significant after Bonferroni's corrections. Further multivariate logistic regression and multifactor dimensionality reduction analyses of interactions between these genes showed that under adjustment of clinical factors, the epilepsy treatment outcomes were significantly associated with the genotype combinations of GABRA1 rs6883877, GABRA2 rs511310 and GABRA3 rs4828696 (p < 0.0001; adjusted r(2) = 0.149). CONCLUSION Our results indicated that genetic variants in the α subunits of GABA(A) receptors may interactively affect the treatment responses of antiepileptic drugs. Further replication using an independent sample collection would be essential to confirm our findings.
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Affiliation(s)
- Chin-Chuan Hung
- Department of Pharmacy, College of Pharmacy, China Medical University, Taichung, Taiwan and Department of Pharmacy, China Medical University Hospital, Taichung, Taiwan
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88
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Miller PS, Aricescu AR. Crystal structure of a human GABAA receptor. Nature 2014; 512:270-5. [PMID: 24909990 PMCID: PMC4167603 DOI: 10.1038/nature13293] [Citation(s) in RCA: 526] [Impact Index Per Article: 52.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/28/2014] [Indexed: 01/01/2023]
Abstract
Type-A γ-aminobutyric acid receptors (GABAARs) are the principal mediators of rapid inhibitory synaptic transmission in the human brain. A decline in GABAAR signalling triggers hyperactive neurological disorders such as insomnia, anxiety and epilepsy. Here we present the first three-dimensional structure of a GABAAR, the human β3 homopentamer, at 3 Å resolution. This structure reveals architectural elements unique to eukaryotic Cys-loop receptors, explains the mechanistic consequences of multiple human disease mutations and shows an unexpected structural role for a conserved N-linked glycan. The receptor was crystallized bound to a previously unknown agonist, benzamidine, opening a new avenue for the rational design of GABAAR modulators. The channel region forms a closed gate at the base of the pore, representative of a desensitized state. These results offer new insights into the signalling mechanisms of pentameric ligand-gated ion channels and enhance current understanding of GABAergic neurotransmission.
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Affiliation(s)
- Paul S Miller
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - A Radu Aricescu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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89
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Deidda G, Bozarth IF, Cancedda L. Modulation of GABAergic transmission in development and neurodevelopmental disorders: investigating physiology and pathology to gain therapeutic perspectives. Front Cell Neurosci 2014; 8:119. [PMID: 24904277 PMCID: PMC4033255 DOI: 10.3389/fncel.2014.00119] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/14/2014] [Indexed: 01/30/2023] Open
Abstract
During mammalian ontogenesis, the neurotransmitter GABA is a fundamental regulator of neuronal networks. In neuronal development, GABAergic signaling regulates neural proliferation, migration, differentiation, and neuronal-network wiring. In the adult, GABA orchestrates the activity of different neuronal cell-types largely interconnected, by powerfully modulating synaptic activity. GABA exerts these functions by binding to chloride-permeable ionotropic GABAA receptors and metabotropic GABAB receptors. According to its functional importance during development, GABA is implicated in a number of neurodevelopmental disorders such as autism, Fragile X, Rett syndrome, Down syndrome, schizophrenia, Tourette's syndrome and neurofibromatosis. The strength and polarity of GABAergic transmission is continuously modulated during physiological, but also pathological conditions. For GABAergic transmission through GABAA receptors, strength regulation is achieved by different mechanisms such as modulation of GABAA receptors themselves, variation of intracellular chloride concentration, and alteration in GABA metabolism. In the never-ending effort to find possible treatments for GABA-related neurological diseases, of great importance would be modulating GABAergic transmission in a safe and possibly physiological way, without the dangers of either silencing network activity or causing epileptic seizures. In this review, we will discuss the different ways to modulate GABAergic transmission normally at work both during physiological and pathological conditions. Our aim is to highlight new research perspectives for therapeutic treatments that reinstate natural and physiological brain functions in neuro-pathological conditions.
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Affiliation(s)
- Gabriele Deidda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Ignacio F Bozarth
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
| | - Laura Cancedda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia Genova, Italy
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90
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Hintersteiner J, Haider M, Luger D, Schwarzer C, Reznicek G, Jäger W, Khom S, Mihovilovic MD, Hering S. Esters of valerenic acid as potential prodrugs. Eur J Pharmacol 2014; 735:123-31. [PMID: 24680924 PMCID: PMC4062961 DOI: 10.1016/j.ejphar.2014.03.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/07/2014] [Accepted: 03/19/2014] [Indexed: 11/15/2022]
Abstract
Valerenic acid (VA) is a β2/3 subunit-specific modulator of γ-aminobutyric acid (GABA) type A (GABAA) receptors inducing anxiolysis. Here we analyze if VA-esters can serve as prodrugs and if different ester structures have different in vitro/in vivo effects. Modulation of GABAA receptors expressed in Xenopus oocytes was studied with 2-microelectrode-voltage-clamp. Anxiolytic effects of the VA-esters were studied on male C57BL/6N mice by means of the elevated plus maze-test; anticonvulsant properties were deduced from changes in seizure threshold upon pentylenetetrazole infusion. VA was detected in plasma confirming hydrolysis of the esters and release of VA in vivo. Esterification significantly reduced the positive allosteric modulation of GABAA (α1β3γ2S) receptors in vitro. in vivo, the studied VA-ester derivatives induced similar or even stronger anxiolytic and anticonvulsant action than VA. While methylation and propylation of VA resulted in faster onset of anxiolysis, the action of VA-ethylester was longer lasting, but occurred with a significant delay. The later finding is in line with the longer lasting anticonvulsant effects of this compound. The estimated VA plasma concentrations provided first insight into the release kinetics from different VA-esters. This might be an important step for its future clinical application as a potential non-sedative anxiolytic and anticonvulsant.
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Affiliation(s)
- Juliane Hintersteiner
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Maximilian Haider
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Denise Luger
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Christoph Schwarzer
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr-Straße 1, 1a A-6020 Innsbruck, Austria.
| | - Gottfried Reznicek
- Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Walter Jäger
- Department of Clinical Pharmacy and Diagnostics, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Sophia Khom
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
| | - Marko D Mihovilovic
- Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, A-1060 Vienna, Austria.
| | - Steffen Hering
- Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
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91
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Fritschy JM, Panzanelli P. GABAAreceptors and plasticity of inhibitory neurotransmission in the central nervous system. Eur J Neurosci 2014; 39:1845-65. [DOI: 10.1111/ejn.12534] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and ETH; Zurich Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini; University of Turin; Turin Italy
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92
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Bode A, Lynch JW. The impact of human hyperekplexia mutations on glycine receptor structure and function. Mol Brain 2014; 7:2. [PMID: 24405574 PMCID: PMC3895786 DOI: 10.1186/1756-6606-7-2] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/07/2014] [Indexed: 01/11/2023] Open
Abstract
Hyperekplexia is a rare neurological disorder characterized by neonatal hypertonia, exaggerated startle responses to unexpected stimuli and a variable incidence of apnoea, intellectual disability and delays in speech acquisition. The majority of motor defects are successfully treated by clonazepam. Hyperekplexia is caused by hereditary mutations that disrupt the functioning of inhibitory glycinergic synapses in neuromotor pathways of the spinal cord and brainstem. The human glycine receptor α1 and β subunits, which predominate at these synapses, are the major targets of mutations. International genetic screening programs, that together have analysed several hundred probands, have recently generated a clear picture of genotype-phenotype correlations and the prevalence of different categories of hyperekplexia mutations. Focusing largely on this new information, this review seeks to summarise the effects of mutations on glycine receptor structure and function and how these functional alterations lead to hyperekplexia.
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Affiliation(s)
| | - Joseph W Lynch
- Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Queensland 4072, Australia.
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93
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Förstera B, a Dzaye OD, Winkelmann A, Semtner M, Benedetti B, Markovic DS, Synowitz M, Wend P, Fähling M, Junier MP, Glass R, Kettenmann H, Meier JC. Intracellular glycine receptor function facilitates glioma formation in vivo. J Cell Sci 2014; 127:3687-98. [DOI: 10.1242/jcs.146662] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The neuronal function of Cys-loop neurotransmitter receptors is established; however, their role in non-neuronal cells is poorly defined. As brain tumors accumulate the neurotransmitter glycine, we studied expression and function of glycine receptors (GlyR) in glioma cells. Human brain tumor biopsies selectively expressed GlyR subunits with nuclear import signal (NLS, α1 and α3). The mouse glioma cell line GL261 expressed GlyR α1, and knock-down of α1 protein expression impaired self-renewal capacity and tumorigenicity of GL261 glioma cells as evidenced by the neurosphere assay and GL261 cell inoculation in vivo, respectively. We furthermore show that the pronounced tumorigenic effect of GlyR α1 relies on a new intracellular signaling function that depends on the NLS region in the large cytosolic loop and impacts on GL261 glioma cell gene regulation. Stable expression of GlyR α1 and α3 loops rescued self-renewal capacity of GlyR α1 knock-down cells, which demonstrates their functional equivalence. The new intracellular signaling function identified here goes beyond the well-established role of GlyRs as neuronal ligand-gated ion channels and defines NLS-containing GlyRs as novel potential targets for brain tumor therapies.
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94
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Bode A, Wood SE, Mullins JGL, Keramidas A, Cushion TD, Thomas RH, Pickrell WO, Drew CJG, Masri A, Jones EA, Vassallo G, Born AP, Alehan F, Aharoni S, Bannasch G, Bartsch M, Kara B, Krause A, Karam EG, Matta S, Jain V, Mandel H, Freilinger M, Graham GE, Hobson E, Chatfield S, Vincent-Delorme C, Rahme JE, Afawi Z, Berkovic SF, Howell OW, Vanbellinghen JF, Rees MI, Chung SK, Lynch JW. New hyperekplexia mutations provide insight into glycine receptor assembly, trafficking, and activation mechanisms. J Biol Chem 2013; 288:33745-33759. [PMID: 24108130 DOI: 10.1074/jbc.m113.509240] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hyperekplexia is a syndrome of readily provoked startle responses, alongside episodic and generalized hypertonia, that presents within the first month of life. Inhibitory glycine receptors are pentameric ligand-gated ion channels with a definitive and clinically well stratified linkage to hyperekplexia. Most hyperekplexia cases are caused by mutations in the α1 subunit of the human glycine receptor (hGlyR) gene (GLRA1). Here we analyzed 68 new unrelated hyperekplexia probands for GLRA1 mutations and identified 19 mutations, of which 9 were novel. Electrophysiological analysis demonstrated that the dominant mutations p.Q226E, p.V280M, and p.R414H induced spontaneous channel activity, indicating that this is a recurring mechanism in hGlyR pathophysiology. p.Q226E, at the top of TM1, most likely induced tonic activation via an enhanced electrostatic attraction to p.R271 at the top of TM2, suggesting a structural mechanism for channel activation. Receptors incorporating p.P230S (which is heterozygous with p.R65W) desensitized much faster than wild type receptors and represent a new TM1 site capable of modulating desensitization. The recessive mutations p.R72C, p.R218W, p.L291P, p.D388A, and p.E375X precluded cell surface expression unless co-expressed with α1 wild type subunits. The recessive p.E375X mutation resulted in subunit truncation upstream of the TM4 domain. Surprisingly, on the basis of three independent assays, we were able to infer that p.E375X truncated subunits are incorporated into functional hGlyRs together with unmutated α1 or α1 plus β subunits. These aberrant receptors exhibit significantly reduced glycine sensitivity. To our knowledge, this is the first suggestion that subunits lacking TM4 domains might be incorporated into functional pentameric ligand-gated ion channel receptors.
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Affiliation(s)
- Anna Bode
- University of Queensland, Queensland Brain Institute and School of Biomedical Sciences, Queensland 4072, Australia
| | - Sian-Elin Wood
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Jonathan G L Mullins
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Angelo Keramidas
- University of Queensland, Queensland Brain Institute and School of Biomedical Sciences, Queensland 4072, Australia
| | - Thomas D Cushion
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Rhys H Thomas
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - William O Pickrell
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Cheney J G Drew
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Amira Masri
- Department of Paediatrics, Division of Child Neurology, Faculty of Medicine, University of Jordan, Amman 11942, Jordan
| | - Elizabeth A Jones
- Manchester Centre for Genomic Medicine, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Sciences Centre, Manchester M13 9WL, United Kingdom; Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester Academic Health Sciences Centre, Manchester M13 9WL, United Kingdom
| | - Grace Vassallo
- Royal Manchester Children's Hospital, Central Manchester University Hospitals National Health Service Foundation Trust, Manchester Academic Health Sciences Centre, Manchester M13 9WL, United Kingdom
| | - Alfred P Born
- Department of Pediatrics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Fusun Alehan
- Department of Pediatrics, Division of Child Neurology, Faculty of Medicine, Basşkent University, 06990 Ankara, Turkey
| | - Sharon Aharoni
- Institute of Pediatric Neurology, Schneider Children's Medical Center of Israel, Petah Tikva 49202, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69987, Israel
| | - Gerald Bannasch
- Neurology Department, Affinity Medical Group, Menasha, Wisconsin 54952
| | - Marius Bartsch
- Department of Neonatology, University Medical Center of the Johannes Gutenberg University Mainz, D-55099 Mainz, Germany
| | - Bulent Kara
- Kocaeli University Medical Faculty, Department of Pediatrics, Division of Child Neurology, 41380 Kocaeli, Turkey
| | - Amanda Krause
- Division of Human Genetics, National Health Laboratory Service, and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, 2000 Johannesburg, South Africa
| | - Elie G Karam
- Department of Psychiatry and Clinical Psychology, Saint George Hospital University Medical Center, Balamand University, Faculty of Medicine, Beirut 1100 2807, Lebanon
| | - Stephanie Matta
- Department of Psychiatry and Clinical Psychology, Saint George Hospital University Medical Center, Balamand University, Faculty of Medicine, Beirut 1100 2807, Lebanon
| | - Vivek Jain
- Royal Children's Hospital Melbourne, Children's Neuroscience Centre, Royal Children's Hospital, Victoria 3052, Australia
| | - Hanna Mandel
- Metabolic Unit, Meyer Children's Hospital, Rambam Medical Center, Technion Faculty of Medicine, Haifa 31096, Israel
| | - Michael Freilinger
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, 1090 Vienna, Austria
| | - Gail E Graham
- Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Ontario K1H 8L1, Canada
| | - Emma Hobson
- Yorkshire Regional Genetic Service, Chapel Allerton Hospital, Leeds, West Yorkshire LS9 7TF, United Kingdom
| | - Sue Chatfield
- Neonatal Unit, Bradford Royal Infirmary, Bradford, West Yorkshire BD9 6RJ, United Kingdom
| | | | | | - Zaid Afawi
- Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Samuel F Berkovic
- Epilepsy Research Centre, Melbourne Brain Centre, Austin Health, Heidelberg 3084, Victoria, Australia
| | - Owain W Howell
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | | | - Mark I Rees
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Seo-Kyung Chung
- Department of Neurology Research and Molecular Neuroscience, Institute of Life Science, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom; Wales Epilepsy Research Network, College of Medicine, Swansea University Swansea SA2 8PP, United Kingdom
| | - Joseph W Lynch
- University of Queensland, Queensland Brain Institute and School of Biomedical Sciences, Queensland 4072, Australia.
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95
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GABAA receptor-mediated tonic depolarization in developing neural circuits. Mol Neurobiol 2013; 49:702-23. [PMID: 24022163 DOI: 10.1007/s12035-013-8548-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/27/2013] [Indexed: 12/25/2022]
Abstract
The activation of GABAA receptors (the type A receptors for γ-aminobutyric acid) produces two distinct forms of responses, phasic (i.e., transient) and tonic (i.e., persistent), that are mediated by synaptic and extrasynaptic GABAA receptors, respectively. During development, the intracellular chloride levels are high so activation of these receptors causes a net outward flow of anions that leads to neuronal depolarization rather than hyperpolarization. Therefore, in developing neural circuits, tonic activation of GABAA receptors may provide persistent depolarization. Recently, it became evident that GABAA receptor-mediated tonic depolarization alters the structure of patterned spontaneous activity, a feature that is common in developing neural circuits and is important for neural circuit refinement. Thus, this persistent depolarization may lead to a long-lasting increase in intracellular calcium level that modulates network properties via calcium-dependent signaling cascades. This article highlights the features of GABAA receptor-mediated tonic depolarization, summarizes the principles for discovery, reviews the current findings in diverse developing circuits, examines the underlying molecular mechanisms and modulation systems, and discusses their functional specializations for each developing neural circuit.
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96
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New insights in endogenous modulation of ligand-gated ion channels: histamine is an inverse agonist at strychnine sensitive glycine receptors. Eur J Pharmacol 2013; 710:59-66. [PMID: 23603522 DOI: 10.1016/j.ejphar.2013.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 01/18/2023]
Abstract
Histamine is involved in many physiological functions in the periphery and is an important neurotransmitter in the brain. It acts on metabotropic H1-H4 receptors mediating vasodilatation, bronchoconstriction and stimulation of gastric acid secretion. In the brain histamine is produced by neurons in the tuberomamillary nucleus (TMN), which controls arousal. Histamine is also a positive modulator of the inhibitory Cys-loop ligand-gated ion channel GABAA. We investigated now its effect on the second member of inhibitory Cys-loop ligand-gated ion channels, the strychnine sensitive glycine receptor. We expressed different human and rat glycine receptor subunits in Xenopus laevis oocytes and characterized the effect of histamine using the two electrode voltage clamp technique. Furthermore we investigated native glycine receptors in hypothalamic neurons using the patch-clamp technique. Histamine inhibited α1β glycine receptors with an IC50 of 5.2±0.3 mM. In presence of 10 mM histamine the glycine dose-response curve was shifted, increasing the EC50 for glycine from 25.5±1.4 μM to 42.4±2.3 μM. In addition, histamine blocked the spontaneous activity of RNA-edited α3β glycine receptors. Histamine inhibited glycine receptors expressed in hypothalamic TMN neurons with an IC50 of 4.6±0.3 mM. Our results give strong evidence that histamine is acting on the same binding site as glycine, being an inverse agonist that competitively antagonizes glycine receptors. Thus, we revealed histamine as an endogenous modulator of glycine receptors.
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97
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Machuca-Parra AI, Miledi R, Martínez-Torres A. Identification of the minimal promoter for specific expression of the GABAρ1 receptor in retinal bipolar cells. J Neurochem 2013; 124:175-88. [PMID: 23106649 DOI: 10.1111/jnc.12067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 09/26/2012] [Accepted: 10/23/2012] [Indexed: 11/29/2022]
Abstract
γ-aminobutyric acid (GABA)ρ receptors regulate rapid synaptic ion currents in the axon end of retinal ON bipolar neurons, acting as a point of control along the visual pathway. In the GABAρ1 subunit knock out mouse, inhibition mediated by this receptor is totally eliminated, showing its role in neural transmission in retina. GABAρ1 mRNA is expressed in mouse retina after post-natal day 7, but little is known about its transcriptional regulation. To identify the GABAρ1 promoter, in silico analyses were performed and indicated that a 0.290-kb fragment, flanking the 5'-end of the GABAρ1 gene, includes putative transcription factor-binding sites, two Inr elements, and lacks a TATA-box. A rapid amplification of cDNA ends (RACE) assay showed three transcription start sites (TSS) clustered in the first exon. Luciferase reporter assays indicated that a 0.232-kb fragment upstream from the ATG is the minimal promoter in transfected cell lines and in vitro electroporated retinae. The second Inr and AP1 site are important to activate transcription in secretin tumor cells (STC-1) and retina. Finally, the 0.232-kb fragment drives green fluorescent protein (GFP) expression to the inner nuclear layer, where bipolar cells are present. This first work paves the way for further studies of molecular elements that control GABAρ1 transcription and regulate its expression during retinal development.
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Affiliation(s)
- Arturo Israel Machuca-Parra
- Departamento de Neurobiología Celular y Molecular, Universidad Nacional Autónoma de México, Instituto de Neurobiología, Querétaro, Mexico
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98
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Namjoshi OA, Wang ZJ, Rallapalli SK, Johnson EM, Johnson YT, Ng H, Ramerstorfer J, Varagic Z, Sieghart W, Majumder S, Roth BL, Rowlett JK, Cook JM. Search for α3β₂/₃γ2 subtype selective ligands that are stable on human liver microsomes. Bioorg Med Chem 2012; 21:93-101. [PMID: 23218469 DOI: 10.1016/j.bmc.2012.10.057] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/22/2012] [Accepted: 10/31/2012] [Indexed: 11/27/2022]
Abstract
Selective modulation of specific benzodiazepine receptor (BzR) gamma amino butyric acid-A (GABA(A)) receptor ion channels has been identified as an important method for separating out the variety of pharmacological effects elicited by BzR-related drugs. Importantly, it has been demonstrated that both α2β(2/3)γ2 (α2BzR) and α3BzR (and/or α2/α3) BzR subtype selective ligands exhibit anxiolytic effects with little or no sedation. Previously we have identified several such ligands; however, three of our parent ligands exhibited significant metabolic liability in rodents in the form of a labile ester group. Here eight analogs are reported which were designed to circumvent this liability by utilizing a rational replacement of the ester moiety based on medicinal chemistry precedents. In a metabolic stability study using human liver microsomes, four compounds were found to undergo slower metabolic transformation, as compared to their corresponding ester analogs. These compounds were also evaluated in in vitro efficacy assays. Additionally, bioisostere 11 was evaluated in a rodent model of anxiety. It exhibited anxiolytic activity at doses of 10 and 100mg/kg and was devoid of sedative properties.
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Affiliation(s)
- Ojas A Namjoshi
- Department of Chemistry, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, WI 53211, USA
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Montori S, DosAnjos S, Poole A, Regueiro-Purriños MM, Llorente IL, Darlison MG, Fernández-López A, Martínez-Villayandre B. Differential effect of transient global ischaemia on the levels of γ-aminobutyric acid type A (GABAA) receptor subunit mRNAs in young and older rats. Neuropathol Appl Neurobiol 2012; 38:710-22. [DOI: 10.1111/j.1365-2990.2012.01254.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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100
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Abstract
The GABA(A) receptors are the major inhibitory neurotransmitter receptors in mammalian brain. Each isoform consists of five homologous or identical subunits surrounding a central chloride ion-selective channel gated by GABA. How many isoforms of the receptor exist is far from clear. GABA(A) receptors located in the postsynaptic membrane mediate neuronal inhibition that occurs in the millisecond time range; those located in the extrasynaptic membrane respond to ambient GABA and confer long-term inhibition. GABA(A) receptors are responsive to a wide variety of drugs, e.g. benzodiazepines, which are often used for their sedative/hypnotic and anxiolytic effects.
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Affiliation(s)
- Erwin Sigel
- Institute of Biochemistry and Molecular Medicine, University of Bern, CH-3012 Bern, Switzerland.
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