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Luscher B, Maguire JL, Rudolph U, Sibille E. GABA A receptors as targets for treating affective and cognitive symptoms of depression. Trends Pharmacol Sci 2023; 44:586-600. [PMID: 37543478 PMCID: PMC10511219 DOI: 10.1016/j.tips.2023.06.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 06/23/2023] [Accepted: 06/23/2023] [Indexed: 08/07/2023]
Abstract
In the past 20 years, our understanding of the pathophysiology of depression has evolved from a focus on an imbalance of monoaminergic neurotransmitters to a multifactorial picture including an improved understanding of the role of glutamatergic excitatory and GABAergic inhibitory neurotransmission. FDA-approved treatments targeting the glutamatergic [esketamine for major depressive disorder (MDD)] and GABAergic (brexanolone for peripartum depression) systems have become available. This review focuses on the GABAA receptor (GABAAR) system as a target for novel antidepressants and discusses the mechanisms by which modulation of δ-containing GABAARs with neuroactive steroids (NASs) or of α5-containing GABAARs results in antidepressant or antidepressant-like actions and discusses clinical data on NASs. Moreover, a potential mechanism by which α5-GABAAR-positive allosteric modulators (PAMs) may improve cognitive deficits in depression is presented.
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Affiliation(s)
- Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Department of Psychiatry, Pennsylvania State University, University Park, PA 16802, USA; Penn State Neuroscience Institute, Pennsylvania State University, University Park, PA 16802, USA
| | - Jamie L Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Uwe Rudolph
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
| | - Etienne Sibille
- Campbell Family Mental Health Research Institute of the Centre for Addiction and Mental Health, University of Toronto, Toronto, ON, Canada; Department of Psychiatry, University of Toronto, Toronto, ON, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
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2
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Belelli D, Hales TG, Lambert JJ, Luscher B, Olsen R, Peters JA, Rudolph U, Sieghart W. GABA A receptors in GtoPdb v.2021.3. IUPHAR BPS Guide Pharm CITE 2021; 2021. [PMID: 35005623 DOI: 10.2218/gtopdb/f72/2021.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The GABAA receptor is a ligand-gated ion channel of the Cys-loop family that includes the nicotinic acetylcholine, 5-HT3 and strychnine-sensitive glycine receptors. GABAA receptor-mediated inhibition within the CNS occurs by fast synaptic transmission, sustained tonic inhibition and temporally intermediate events that have been termed 'GABAA, slow' [45]. GABAA receptors exist as pentamers of 4TM subunits that form an intrinsic anion selective channel. Sequences of six α, three β, three γ, one δ, three ρ, one ε, one π and one θ GABAA receptor subunits have been reported in mammals [278, 235, 236, 283]. The π-subunit is restricted to reproductive tissue. Alternatively spliced versions of many subunits exist (e.g. α4- and α6- (both not functional) α5-, β2-, β3- and γ2), along with RNA editing of the α3 subunit [71]. The three ρ-subunits, (ρ1-3) function as either homo- or hetero-oligomeric assemblies [359, 50]. Receptors formed from ρ-subunits, because of their distinctive pharmacology that includes insensitivity to bicuculline, benzodiazepines and barbiturates, have sometimes been termed GABAC receptors [359], but they are classified as GABA A receptors by NC-IUPHAR on the basis of structural and functional criteria [16, 235, 236]. Many GABAA receptor subtypes contain α-, β- and γ-subunits with the likely stoichiometry 2α.2β.1γ [168, 235]. It is thought that the majority of GABAA receptors harbour a single type of α- and β - subunit variant. The α1β2γ2 hetero-oligomer constitutes the largest population of GABAA receptors in the CNS, followed by the α2β3γ2 and α3β3γ2 isoforms. Receptors that incorporate the α4- α5-or α 6-subunit, or the β1-, γ1-, γ3-, δ-, ε- and θ-subunits, are less numerous, but they may nonetheless serve important functions. For example, extrasynaptically located receptors that contain α6- and δ-subunits in cerebellar granule cells, or an α4- and δ-subunit in dentate gyrus granule cells and thalamic neurones, mediate a tonic current that is important for neuronal excitability in response to ambient concentrations of GABA [209, 272, 83, 19, 288]. GABA binding occurs at the β+/α- subunit interface and the homologous γ+/α- subunits interface creates the benzodiazepine site. A second site for benzodiazepine binding has recently been postulated to occur at the α+/β- interface ([254]; reviewed by [282]). The particular α-and γ-subunit isoforms exhibit marked effects on recognition and/or efficacy at the benzodiazepine site. Thus, receptors incorporating either α4- or α6-subunits are not recognised by 'classical' benzodiazepines, such as flunitrazepam (but see [356]). The trafficking, cell surface expression, internalisation and function of GABAA receptors and their subunits are discussed in detail in several recent reviews [52, 140, 188, 316] but one point worthy of note is that receptors incorporating the γ2 subunit (except when associated with α5) cluster at the postsynaptic membrane (but may distribute dynamically between synaptic and extrasynaptic locations), whereas as those incorporating the δ subunit appear to be exclusively extrasynaptic. NC-IUPHAR [16, 235, 3, 2] class the GABAA receptors according to their subunit structure, pharmacology and receptor function. Currently, eleven native GABAA receptors are classed as conclusively identified (i.e., α1β2γ2, α1βγ2, α3βγ2, α4βγ2, α4β2δ, α4β3δ, α5βγ2, α6βγ2, α6β2δ, α6β3δ and ρ) with further receptor isoforms occurring with high probability, or only tentatively [235, 236]. It is beyond the scope of this Guide to discuss the pharmacology of individual GABAA receptor isoforms in detail; such information can be gleaned in the reviews [16, 95, 168, 173, 143, 278, 216, 235, 236] and [9, 10]. Agents that discriminate between α-subunit isoforms are noted in the table and additional agents that demonstrate selectivity between receptor isoforms, for example via β-subunit selectivity, are indicated in the text below. The distinctive agonist and antagonist pharmacology of ρ receptors is summarised in the table and additional aspects are reviewed in [359, 50, 145, 223]. Several high-resolution cryo-electron microscopy structures have been described in which the full-length human α1β3γ2L GABAA receptor in lipid nanodiscs is bound to the channel-blocker picrotoxin, the competitive antagonist bicuculline, the agonist GABA (γ-aminobutyric acid), and the classical benzodiazepines alprazolam and diazepam [198].
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3
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Malyshev AV, Sukhanova IA, Zlobin AS, Gedzun VR, Pavshintsev VV, Vasileva EV, Zalevsky AO, Doronin II, Mitkin NA, Golovin AV, Lovat ML, Kovalev GI, Zolotarev YA, Kuchumov AR, Babkin GA, Luscher B. In silico Screening and Behavioral Validation of a Novel Peptide, LCGA-17, With Anxiolytic-Like Properties. Front Neurosci 2021; 15:705590. [PMID: 34421525 PMCID: PMC8372404 DOI: 10.3389/fnins.2021.705590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/13/2021] [Indexed: 12/01/2022] Open
Abstract
The aim of the study was to develop better anxiolytics and antidepressants. We focused on GABAA receptors and the α2δ auxiliary subunit of V-gated Ca2+ channels as putative targets because they are established as mediators of efficacious anxiolytics, antidepressants, and anticonvulsants. We further focused on short peptides as candidate ligands because of their high safety and tolerability profiles. We employed a structural bioinformatics approach to develop novel tetrapeptides with predicted affinity to GABAA receptors and α2δ. In silico docking studies of one of these peptides, LCGA-17, showed a high binding score for both GABAA receptors and α2δ, combined with anxiolytic-like properties in a Danio rerio behavioral screen. LCGA-17 showed anxiolytic-like effects in the novel tank test, the light–dark box, and the social preference test, with efficacy comparable to fluvoxamine and diazepam. In binding assays using rat brain membranes, [3H]-LCGA-17 was competed more effectively by gabapentinoid ligands of α2δ than ligands of GABAA receptors, suggesting that α2δ represents a likely target for LCGA-17. [3H]-LCGA-17 binding to brain lysates was unaffected by competition with ligands for GABAB, glutamate, dopamine, serotonin, and other receptors, suggesting specific interaction with α2δ. Dose-finding studies in mice using acute administration of LCGA-17 (i.p.) demonstrated anxiolytic-like effects in the open field test, elevated plus maze, and marble burying tests, as well as antidepressant-like properties in the forced swim test. The anxiolytic effects were effectively blocked by bicuculline. Therefore, LCGA-17 is a novel candidate anxiolytic and antidepressant that may act through α2δ, with possible synergism by GABAA receptors.
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Affiliation(s)
| | | | - Alexander S Zlobin
- Lactocore, Inc., Plymouth, MI, United States.,Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.,Sirius University of Science and Technology, Sochi, Russia
| | - Vasilina R Gedzun
- Lactocore, Inc., Plymouth, MI, United States.,Department of Human and Animal Physiology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Ekaterina V Vasileva
- Federal State Budgetary Institution, Research Zakusov Institute of Pharmacology, Moscow, Russia
| | - Arthur O Zalevsky
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | | | | | - Andrey V Golovin
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.,Sirius University of Science and Technology, Sochi, Russia
| | - Maxim L Lovat
- Department of Human and Animal Physiology, Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Georgy I Kovalev
- Federal State Budgetary Institution, Research Zakusov Institute of Pharmacology, Moscow, Russia
| | - Yurii A Zolotarev
- Institute of Molecular Genetics of National Research Centre "Kurchatov Institute", Moscow, Russia
| | | | | | - Bernhard Luscher
- Department of Biology, The Pennsylvania State University, University Park, PA, United States.,Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, United States
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McSweeney C, Dong F, Chen M, Vitale J, Xu L, Crowley N, Luscher B, Zou D, Mao Y. Full function of exon junction complex factor, Rbm8a, is critical for interneuron development. Transl Psychiatry 2020; 10:379. [PMID: 33154347 PMCID: PMC7644723 DOI: 10.1038/s41398-020-01065-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 09/16/2020] [Accepted: 10/20/2020] [Indexed: 12/12/2022] Open
Abstract
The formation of the nervous system requires a balance between proliferation, differentiation, and migration of neural progenitors (NPs). Mutations in genes regulating development impede neurogenesis and lead to neuropsychiatric diseases, including autism spectrum disorders (ASDs) and schizophrenia (SZ). Recently, mutations in nonsense-mediated mRNA decay genes have been associated with ASDs, intellectual disability (ID), and SZ. Here, we examine the function of a gene in the exon junction complex, Rbm8a, in the cortical development. When Rbm8a is selectively knocked out in neural stem cells, the resulting mice exhibit microcephaly, early postnatal lethality, and altered distribution of excitatory neurons in the neocortex. Moreover, Rbm8a haploinsufficiency in the central nervous system decreases cell proliferation in the ganglionic eminences. Parvalbumin+ and neuropeptide Y+ interneurons in the cortex are significantly reduced, and distribution of interneurons are altered. Consistently, neurons in the cortex of conditional knockout (cKO) mice show a significant decrease in GABA frequency. Transcriptomic analysis revealed differentially expressed genes enriched in telencephalon development and mitosis. To further investigate the role of Rbm8a in interneuron differentiation, conditional KO of Rbm8a in NKX2.1 interneuron progenitor cells reduces progenitor proliferation and alters interneuron distributions. Taken together, these data reveal a critical role of Rbm8a in interneuron development, and establish that perturbation of this gene leads to profound cortical deficits.
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Affiliation(s)
- Colleen McSweeney
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Fengping Dong
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Miranda Chen
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Jessica Vitale
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Li Xu
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA ,grid.268505.c0000 0000 8744 8924Zhejiang Chinese Medical University, 310053 Hangzhou, Zhejiang China
| | - Nicole Crowley
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Bernhard Luscher
- grid.29857.310000 0001 2097 4281Department of Biology, Pennsylvania State University, University Park, PA 16802 USA ,grid.29857.310000 0001 2097 4281Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802 USA
| | - Donghua Zou
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA. .,Department of Neurology, The Fifth Affiliated Hospital of Guangxi Medical University, 530021, Nanning, Guangxi, China.
| | - Yingwei Mao
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.
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5
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Jefferson SJ, Feng M, Chon UR, Guo Y, Kim Y, Luscher B. Disinhibition of somatostatin interneurons confers resilience to stress in male but not female mice. Neurobiol Stress 2020; 13:100238. [PMID: 33344694 PMCID: PMC7739040 DOI: 10.1016/j.ynstr.2020.100238] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/22/2020] [Accepted: 07/01/2020] [Indexed: 12/16/2022] Open
Abstract
Chronic stress represents a vulnerability factor for anxiety and depressive disorders and has been widely used to model aspects of these disorders in rodents. Disinhibition of somatostatin (SST)-positive GABAergic interneurons in mice by deletion of γ2 GABAA receptors selectively from these cells (SSTCre:γ2f/f mice) has been shown to result in behavioral and biochemical changes that mimic the responses to antidepressant doses of ketamine. Here we explored the extent to which SSTCre:γ2f/f mice exhibit resilience to unpredictable chronic mild stress (UCMS). We found that male SSTCre:γ2f/f mice are resilient to UCMS-induced (i) reductions in weight gain, (ii) reductions in SST-immuno-positive cells in medial prefrontal cortex (mPFC), (iii) increases in phosphorylation of eukaryotic elongation factor 2 (eEF2) in mPFC, and (iv) increased anxiety in a novelty suppressed feeding test. Female SSTCre:γ2f/f mice were resilient to UCMS-induced reductions in SST-immuno-positive cells indistinguishably from males. However, in contrast to males, they showed no UCMS effects on weight gain independent of genotype. Moreover, in mPFC of female γ2f/f control mice, UCMS resulted in paradoxically reduced p-EF2 levels without stress effects in the SSTCre:γ2f/f mutants. Lastly, female SSTCre:γ2f/f mice showed increased rather than reduced UCMS induced anxiety compared to γ2f/f controls. Thus, disinhibition of SST interneurons results in behavioral resilience to UCMS selectively in male mice, along with cellular resilience of SST neurons to UCMS independent of sex. Thus, mechanisms underlying vulnerability and resilience to stress are sex specific and map to mPFC rather than hippocampus but appear unrelated to changes in expression of SST as a marker of corresponding interneurons.
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Affiliation(s)
- Sarah J. Jefferson
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
- Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Mengyang Feng
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
- Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - URee Chon
- Department of Neural and Behavioral Sciences, College of Medicine, Pennsylvania State University, Hershey, PA, 17033, USA
| | - Yao Guo
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
- Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Yongsoo Kim
- Department of Neural and Behavioral Sciences, College of Medicine, Pennsylvania State University, Hershey, PA, 17033, USA
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA
- Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
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6
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Feng M, Crowley NA, Patel A, Guo Y, Bugni SE, Luscher B. Reversal of a Treatment-Resistant, Depression-Related Brain State with the Kv7 Channel Opener Retigabine. Neuroscience 2019; 406:109-125. [PMID: 30858110 DOI: 10.1016/j.neuroscience.2019.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 12/27/2022]
Abstract
Neuroinflammation is associated with increased vulnerability to diverse psychiatric conditions, including treatment-resistant major depressive disorder (MDD). Here we assessed whether high fat diet (HFD) induced neuroinflammation may be suitable to model a treatment-resistant depressive-like brain state in mice. Male and female mice were fed a HFD for 18 weeks, followed by quantitation of glucose tolerance, inflammatory markers of brain tissue (TNFα, IL-6, IL-1β, Iba-1), neural excitability in the prelimbic cortex (PLC), as well as assessment of emotional reactivity and hedonic behavior in a battery of behavioral tests. In addition, we assessed the behavioral responsiveness of mice to fluoxetine, desipramine, ketamine, and the Kv7 channel opener and anticonvulsant retigabine. HFD exposure led to glucose intolerance and neuroinflammation in male mice, with similar but non-significant trends in females. Neuroinflammation of males was associated with anxious-depressive-like behavior and defects in working memory, along with neural hyperexcitability and increased Ih currents of pyramidal cells in the PLC. The behavioral changes were largely resistant to chronic treatment with fluoxetine and desipramine, as well as ketamine. By contrast, retigabine (also known as ezogabine) normalized neural excitability and Ih currents recorded from slices of HFD-treated animals and significantly ameliorated most of the behavioral impairments, without effects in control diet exposed animals. Thus, treatment resistant depressive-like brain states that are associated with chronic neuroinflammation may involve hyperexcitability of pyramidal neurons and may be effectively treated by retigabine.
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Affiliation(s)
- Mengyang Feng
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Nicole A Crowley
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Akshilkumar Patel
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Yao Guo
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Sierra E Bugni
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802; Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.
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Crowley NA, Magee SN, Feng M, Jefferson SJ, Morris CJ, Dao NC, Brockway DF, Luscher B. Ketamine normalizes binge drinking-induced defects in glutamatergic synaptic transmission and ethanol drinking behavior in female but not male mice. Neuropharmacology 2019; 149:35-44. [PMID: 30731135 DOI: 10.1016/j.neuropharm.2019.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/30/2019] [Accepted: 02/02/2019] [Indexed: 01/06/2023]
Abstract
Ketamine is a fast acting experimental antidepressant with significant therapeutic potential for emotional disorders such as major depressive disorder and alcohol use disorders. Of particular interest is binge alcohol use, which during intermittent withdrawal from drinking involves depressive-like symptoms reminiscent of major depressive disorder. Binge drinking has been successfully modeled in mice with the Drinking in the Dark (DID) paradigm, which involves daily access to 20% ethanol, for a limited duration and selectively during the dark phase of the circadian light cycle. Here we demonstrate that DID exposure reduces the cell surface expression of NMDA- and AMPA-type glutamate receptors in the prelimbic cortex (PLC) of female but not male mice, along with reduced activity of the mammalian target of rapamycin (mTOR) signaling pathway. Pretreatment with an acute subanesthetic dose of ketamine suppresses binge-like ethanol consumption in female but not male mice. Lastly, DID-exposure reduces spontaneous glutamatergic synaptic transmission in the PLC of both sexes, but synaptic transmission is rescued by ketamine selectively in female mice. Thus, ketamine may have therapeutic potential as an ethanol binge suppressing agent selectively in female subjects.
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Affiliation(s)
- Nicole A Crowley
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Sarah N Magee
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Mengyang Feng
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Sarah J Jefferson
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Christian J Morris
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Nigel C Dao
- Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA; Department of Biobehavioral Health, Pennsylvania State University, University Park, PA, 16802, USA
| | - Dakota F Brockway
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA.
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8
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Caruso MJ, Crowley NA, Reiss DE, Caulfield JI, Luscher B, Cavigelli SA, Kamens HM. Adolescent Social Stress Increases Anxiety-like Behavior and Alters Synaptic Transmission, Without Influencing Nicotine Responses, in a Sex-Dependent Manner. Neuroscience 2018; 373:182-198. [PMID: 29343455 DOI: 10.1016/j.neuroscience.2018.01.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 12/19/2017] [Accepted: 01/03/2018] [Indexed: 11/27/2022]
Abstract
Early-life stress is a risk factor for comorbid anxiety and nicotine use. Because little is known about the factors underlying this comorbidity, we investigated the effects of adolescent stress on anxiety-like behavior and nicotine responses within individual animals. Adolescent male and female C57BL/6J mice were exposed to chronic variable social stress (CVSS; repeated cycles of social isolation + social reorganization) or control conditions from postnatal days (PND) 25-59. Anxiety-like behavior and social avoidance were measured in the elevated plus-maze (PND 61-65) and social approach-avoidance test (Experiment 1: PND 140-144; Experiment 2: 95-97), respectively. Acute nicotine-induced locomotor, hypothermic, corticosterone responses, (Experiment 1: PND 56-59; Experiment 2: PND 65-70) and voluntary oral nicotine consumption (Experiment 1: PND 116-135; Experiment 2: 73-92) were also examined. Finally, we assessed prefrontal cortex (PFC) and nucleus accumbens (NAC) synaptic transmission (PND 64-80); brain regions that are implicated in anxiety and addiction. Mice exposed to adolescent CVSS displayed increased anxiety-like behavior relative to controls. Further, CVSS altered synaptic excitability in PFC and NAC neurons in a sex-specific manner. For males, CVSS decreased the amplitude and frequency of spontaneous excitatory postsynaptic currents in the PFC and NAC, respectively. In females, CVSS decreased the amplitude of spontaneous inhibitory postsynaptic currents in the NAC. Adolescent CVSS did not affect social avoidance or nicotine responses and anxiety-like behavior was not reliably associated with nicotine responses within individual animals. Taken together, complex interactions between PFC and NAC function may contribute to adolescent stress-induced anxiety-like behavior without influencing nicotine responses.
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Affiliation(s)
- Michael J Caruso
- Department of Biobehavioral Health, Pennsylvania State University, University Park, PA 16802, USA
| | - Nicole A Crowley
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Dana E Reiss
- Department of Biobehavioral Health, Pennsylvania State University, University Park, PA 16802, USA
| | - Jasmine I Caulfield
- Department of Biobehavioral Health, Pennsylvania State University, University Park, PA 16802, USA; The Huck Institutes for the Life Sciences, Pennsylvania State University, University Park, PA 16892, USA
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA; Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, PA 16802, USA
| | - Sonia A Cavigelli
- Department of Biobehavioral Health, Pennsylvania State University, University Park, PA 16802, USA; Center for Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, PA 16802, USA
| | - Helen M Kamens
- Department of Biobehavioral Health, Pennsylvania State University, University Park, PA 16802, USA.
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Fuchs T, Jefferson SJ, Hooper A, Yee PHP, Maguire J, Luscher B. Disinhibition of somatostatin-positive interneurons by deletion of postsynaptic GABA A receptors. Mol Psychiatry 2017; 22:787. [PMID: 28529315 DOI: 10.1038/mp.2017.110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- T Fuchs
- Department of Biology, Pennsylvania State University, University Park, State College, PA, USA
| | - S J Jefferson
- Department of Biology, Pennsylvania State University, University Park, State College, PA, USA
| | - A Hooper
- Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University, Boston, MA, USA
| | - P-H P Yee
- Department of Biology, Pennsylvania State University, University Park, State College, PA, USA
| | - J Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - B Luscher
- Department of Biology, Pennsylvania State University, University Park, State College, PA, USA.,Department of Biochemistry &Molecular Biology, Pennsylvania State University, University Park, State College, PA, USA.,Center for Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, State College, PA, USA
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10
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Du K, Murakami S, Sun Y, Kilpatrick CL, Luscher B. DHHC7 Palmitoylates Glucose Transporter 4 (Glut4) and Regulates Glut4 Membrane Translocation. J Biol Chem 2017; 292:2979-2991. [PMID: 28057756 DOI: 10.1074/jbc.m116.747139] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 12/30/2016] [Indexed: 11/06/2022] Open
Abstract
Insulin-dependent translocation of glucose transporter 4 (Glut4) to the plasma membrane plays a key role in the dynamic regulation of glucose homeostasis. We recently showed that this process is critically dependent on palmitoylation of Glut4 at Cys-223. To gain further insights into the regulation of Glut4 palmitoylation, we set out to identify the palmitoyl acyltransferase (PAT) involved. Here we report that among 23 mammalian DHHC proteins, DHHC7 is the major Glut4 PAT, based on evidence that ectopic expression of DHHC7 increased Glut4 palmitoylation, whereas DHHC7 knockdown in 3T3-L1 adipocytes and DHHC7 KO in adipose tissue and muscle decreased Glut4 palmitoylation. Moreover, inactivation of DHHC7 suppressed insulin-dependent Glut4 membrane translocation in both 3T3-L1 adipocytes and primary adipocytes. Finally, DHHC7 KO mice developed hyperglycemia and glucose intolerance, thereby confirming that DHHC7 represents the principal PAT for Glut4 and that this mechanism is essential for insulin-regulated glucose homeostasis.
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Affiliation(s)
- Keyong Du
- From the Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111 and
| | | | - Yingmin Sun
- From the Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111 and
| | - Casey L Kilpatrick
- Department of Biochemistry and Molecular Biology.,Department of Biology, and.,Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Bernhard Luscher
- Department of Biochemistry and Molecular Biology.,Department of Biology, and.,Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania 16802
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11
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Kilpatrick CL, Murakami S, Feng M, Wu X, Lal R, Chen G, Du K, Luscher B. Dissociation of Golgi-associated DHHC-type Zinc Finger Protein (GODZ)- and Sertoli Cell Gene with a Zinc Finger Domain-β (SERZ-β)-mediated Palmitoylation by Loss of Function Analyses in Knock-out Mice. J Biol Chem 2016; 291:27371-27386. [PMID: 27875292 DOI: 10.1074/jbc.m116.732768] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 09/28/2016] [Indexed: 11/06/2022] Open
Abstract
The γ2 subunit of GABA type A receptors (GABAARs) is thought to be subject to palmitoylation by both Golgi-associated DHHC-type zinc finger protein (GODZ; also known as DHHC3) and its paralog Sertoli cell gene with a zinc finger domain-β (SERZ-β; DHHC7) based on overexpression of enzymes and substrates in heterologous cells. Here we have further investigated the substrate specificity of these enzymes by characterization of GODZ and SERZ-β knock-out (KO) mice as well as double KO (DKO) neurons. Palmitoylation of γ2 and a second substrate, growth-associated protein of 43 kDa, that is independently implicated in trafficking of GABAARs was significantly reduced in brain of GODZ KO versus wild-type (WT) mice but unaltered in SERZ-β KO mice. Accumulation of GABAARs at synapses, GABAergic innervation, and synaptic function were reduced in GODZ KO and DKO neurons to a similar extent, indicating that SERZ-β does not contribute to palmitoylation or trafficking of GABAARs even in the absence of GODZ. Notably, these effects were seen only when mutant neurons were grown in competition with WT neurons, thereby mimicking conditions of shRNA-transfected neurons previously used to characterize GODZ. However, GABA-evoked whole-cell currents of DKO neurons and the GABAAR cell surface expression in DKO neurons and GODZ or SERZ-β KO brain slices were unaltered, indicating that GODZ-mediated palmitoylation selectively controls the pool of receptors at synapses. The different substrate specificities of GODZ and SERZ-β in vivo were correlated with their differential localization to cis- versus trans-Golgi compartment, a mechanism that was compromised by overexpression of GODZ.
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Affiliation(s)
| | | | | | | | | | - Gong Chen
- Biology and.,the Center for Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Keyong Du
- Molecular Oncology Research Institute, Tufts Medical Center, Boston, Massachusetts 02111
| | - Bernhard Luscher
- From the Departments of Biochemistry and Molecular Biology and .,Biology and.,the Center for Molecular Investigation of Neurological Disorders (CMIND), Pennsylvania State University, University Park, Pennsylvania 16802 and
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12
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Leppä E, Linden AM, Aller MI, Wulff P, Vekovischeva O, Luscher B, Lüddens H, Wisden W, Korpi ER. Increased Motor-Impairing Effects of the Neuroactive Steroid Pregnanolone in Mice with Targeted Inactivation of the GABA A Receptor γ2 Subunit in the Cerebellum. Front Pharmacol 2016; 7:403. [PMID: 27833556 PMCID: PMC5081378 DOI: 10.3389/fphar.2016.00403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/12/2016] [Indexed: 11/20/2022] Open
Abstract
Endogenous neurosteroids and neuroactive steroids have potent and widespread actions on the brain via inhibitory GABAA receptors. In recombinant receptors and genetic mouse models their actions depend on the α, β, and δ subunits of the receptor, especially on those that form extrasynaptic GABAA receptors responsible for non-synaptic (tonic) inhibition, but they also act on synaptically enriched γ2 subunit-containing receptors and even on αβ binary receptors. Here we tested whether behavioral sensitivity to the neuroactive steroid agonist 5β-pregnan-3α-ol-20-one is altered in genetically engineered mouse models that have deficient GABAA receptor-mediated synaptic inhibition in selected neuronal populations. Mouse lines with the GABAA receptor γ2 subunit gene selectively deleted either in parvalbumin-containing cells (including cerebellar Purkinje cells), cerebellar granule cells, or just in cerebellar Purkinje cells were trained on the accelerated rotating rod and then tested for motor impairment after cumulative intraperitoneal dosing of 5β-pregnan-3α-ol-20-one. Motor-impairing effects of 5β-pregnan-3α-ol-20-one were strongly increased in all three mouse models in which γ2 subunit-dependent synaptic GABAA responses in cerebellar neurons were genetically abolished. Furthermore, rescue of postsynaptic GABAA receptors in Purkinje cells normalized the effect of the steroid. Anxiolytic/explorative effects of the steroid in elevated plus maze and light:dark exploration tests in mice with Purkinje cell γ2 subunit inactivation were similar to those in control mice. The results suggest that, when the deletion of γ2 subunit has removed synaptic GABAA receptors from the specific cerebellar neuronal populations, the effects of neuroactive steroids solely on extrasynaptic αβ or αβδ receptors lead to enhanced changes in the cerebellum-generated behavior.
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Affiliation(s)
- Elli Leppä
- Department of Pharmacology, Faculty of Medicine, University of Helsinki Helsinki, Finland
| | - Anni-Maija Linden
- Department of Pharmacology, Faculty of Medicine, University of Helsinki Helsinki, Finland
| | - Maria I Aller
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández de Elche San Juan de Alicante, Spain
| | - Peer Wulff
- Institute of Physiology, University of Kiel Kiel, Germany
| | - Olga Vekovischeva
- Department of Pharmacology, Faculty of Medicine, University of Helsinki Helsinki, Finland
| | - Bernhard Luscher
- Department of Biology, The Pennsylvania State University University Park, PA, USA
| | - Hartmut Lüddens
- Department of Psychiatry and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz Mainz, Germany
| | - William Wisden
- Department of Life Sciences, Imperial College London London, UK
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki Helsinki, Finland
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13
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Ren Z, Pribiag H, Jefferson SJ, Shorey M, Fuchs T, Stellwagen D, Luscher B. Bidirectional Homeostatic Regulation of a Depression-Related Brain State by Gamma-Aminobutyric Acidergic Deficits and Ketamine Treatment. Biol Psychiatry 2016; 80:457-468. [PMID: 27062563 PMCID: PMC4983262 DOI: 10.1016/j.biopsych.2016.02.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 02/06/2016] [Accepted: 02/08/2016] [Indexed: 12/30/2022]
Abstract
BACKGROUND Major depressive disorder is increasingly recognized to involve functional deficits in both gamma-aminobutyric acid (GABA)ergic and glutamatergic synaptic transmission. To elucidate the relationship between these phenotypes, we used GABAA receptor γ2 subunit heterozygous (γ2(+/-)) mice, which we previously characterized as a model animal with construct, face, and predictive validity for major depressive disorder. METHODS To assess possible consequences of GABAergic deficits on glutamatergic transmission, we quantitated the cell surface expression of N-methyl-D-aspartate (NMDA)-type and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)-type glutamate receptors and the function of synapses in the hippocampus and medial prefrontal cortex of γ2(+/-) mice. We also analyzed the effects of an acute dose of the experimental antidepressant ketamine on all these parameters in γ2(+/-) versus wild-type mice. RESULTS Modest defects in GABAergic synaptic transmission of γ2(+/-) mice resulted in a strikingly prominent homeostatic-like reduction in the cell surface expression of NMDA-type and AMPA-type glutamate receptors, along with prominent functional impairment of glutamatergic synapses in the hippocampus and medial prefrontal cortex. A single subanesthetic dose of ketamine normalized glutamate receptor expression and synaptic function of γ2(+/-) mice to wild-type levels for a prolonged period, along with antidepressant-like behavioral consequences selectively in γ2(+/-) mice. The GABAergic synapses of γ2(+/-) mice were potentiated by ketamine in parallel but only in the medial prefrontal cortex. CONCLUSIONS Depressive-like brain states that are caused by GABAergic deficits involve a homeostatic-like reduction of glutamatergic transmission that is reversible by an acute, subanesthetic dose of ketamine, along with regionally selective potentiation of GABAergic synapses. The data merge the GABAergic and glutamatergic deficit hypotheses of major depressive disorder.
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Affiliation(s)
- Zhen Ren
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - Horia Pribiag
- Center for Research in Neuroscience, McGill University, Montreal General Hospital, L7-132, 1650 Cedar Av, Montreal, QC H3G 1A4, Canada
| | - Sarah J. Jefferson
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - Matthew Shorey
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - Thomas Fuchs
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - David Stellwagen
- Center for Research in Neuroscience, McGill University, Montreal General Hospital, L7-132, 1650 Cedar Av, Montreal, QC H3G 1A4, Canada
| | - Bernhard Luscher
- Departments of Biology, Pennsylvania State University, University Park, Pennsylvania; Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania; Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania.
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14
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Abstract
The GABAergic deficit hypothesis of major depressive disorders (MDDs) posits that reduced γ-aminobutyric acid (GABA) concentration in brain, impaired function of GABAergic interneurons, altered expression and function of GABA(A) receptors, and changes in GABAergic transmission dictated by altered chloride homeostasis can contribute to the etiology of MDD. Conversely, the hypothesis posits that the efficacy of currently used antidepressants is determined by their ability to enhance GABAergic neurotransmission. We here provide an update for corresponding evidence from studies of patients and preclinical animal models of depression. In addition, we propose an explanation for the continued lack of genetic evidence that explains the considerable heritability of MDD. Lastly, we discuss how alterations in GABAergic transmission are integral to other hypotheses of MDD that emphasize (i) the role of monoaminergic deficits, (ii) stress-based etiologies, (iii) neurotrophic deficits, and (iv) the neurotoxic and neural circuit-impairing consequences of chronic excesses of glutamate. We propose that altered GABAergic transmission serves as a common denominator of MDD that can account for all these other hypotheses and that plays a causal and common role in diverse mechanistic etiologies of depressive brain states and in the mechanism of action of current antidepressant drug therapies.
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Affiliation(s)
- Bernhard Luscher
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA.
| | - Thomas Fuchs
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, USA
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15
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Affiliation(s)
- Chris J McBain
- Porter Neuroscience Research Center, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Building 35, Room 3C-903, 35 Convent Drive, MSC 3715, Bethesda, MD, 20892-3715, United States.
| | - Josef Kittler
- Porter Neuroscience Research Center, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Building 35, Room 3C-903, 35 Convent Drive, MSC 3715, Bethesda, MD, 20892-3715, United States
| | - Bernhard Luscher
- Porter Neuroscience Research Center, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Building 35, Room 3C-903, 35 Convent Drive, MSC 3715, Bethesda, MD, 20892-3715, United States
| | - Istvan Mody
- Porter Neuroscience Research Center, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Building 35, Room 3C-903, 35 Convent Drive, MSC 3715, Bethesda, MD, 20892-3715, United States
| | - Beverley A Orser
- Porter Neuroscience Research Center, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Building 35, Room 3C-903, 35 Convent Drive, MSC 3715, Bethesda, MD, 20892-3715, United States
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16
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Ren Z, Sahir N, Murakami S, Luellen BA, Earnheart JC, Lal R, Kim JY, Song H, Luscher B. Defects in dendrite and spine maturation and synaptogenesis associated with an anxious-depressive-like phenotype of GABAA receptor-deficient mice. Neuropharmacology 2014; 88:171-9. [PMID: 25107590 DOI: 10.1016/j.neuropharm.2014.07.019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/08/2014] [Accepted: 07/21/2014] [Indexed: 11/27/2022]
Abstract
Mice that were rendered heterozygous for the γ2 subunit of GABAA receptors (γ2(+/-) mice) have been characterized extensively as a model for major depressive disorder. The phenotype of these mice includes behavior indicative of heightened anxiety, despair, and anhedonia, as well as defects in hippocampus-dependent pattern separation, HPA axis hyperactivity and increased responsiveness to antidepressant drugs. The γ2(+/-) model thereby provides strong support for the GABAergic deficit hypothesis of major depressive disorder. Here we show that γ2(+/-) mice additionally exhibit specific defects in late stage survival of adult-born hippocampal granule cells, including reduced complexity of dendritic arbors and impaired maturation of synaptic spines. Moreover, cortical γ2(+/-) neurons cultured in vitro show marked deficits in GABAergic innervation selectively when grown under competitive conditions that may mimic the environment of adult-born hippocampal granule cells. Finally, brain extracts of γ2(+/-) mice show a numerical but insignificant trend (p = 0.06) for transiently reduced expression of brain derived neurotrophic factor (BDNF) at three weeks of age, which might contribute to the previously reported developmental origin of the behavioral phenotype of γ2(+/-) mice. The data indicate increasing congruence of the GABAergic, glutamatergic, stress-based and neurotrophic deficit hypotheses of major depressive disorder.
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Affiliation(s)
- Zhen Ren
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Nadia Sahir
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Shoko Murakami
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Beth A Luellen
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - John C Earnheart
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Rachnanjali Lal
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Ju Young Kim
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hongjun Song
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Bernhard Luscher
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA; Center for Molecular Investigation of Neurological Disorders, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.
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17
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Affiliation(s)
- Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA, USA
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18
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Reid CA, Kim T, Phillips AM, Low J, Berkovic SF, Luscher B, Petrou S. Multiple molecular mechanisms for a single GABAA mutation in epilepsy. Neurology 2013; 80:1003-8. [PMID: 23408872 DOI: 10.1212/wnl.0b013e3182872867] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To understand the molecular basis and differential penetrance of febrile seizures and absence seizures in patients with the γ2(R43Q) GABA receptor mutation. METHODS Spike-and-wave discharges and thermal seizure susceptibility were measured in heterozygous GABA γ2 knock-out and GABA γ2(R43Q) knock-in mice models crossed to different mouse strains. RESULTS By comparing the GABA γ2 knock-out with the GABA γ2(R43Q) knock-in mouse model we show that haploinsufficiency underlies the genesis of absence seizures but cannot account for the thermal seizure susceptibility. Additionally, while the expression of the absence seizure phenotype was very sensitive to mouse background genetics, the thermal seizure phenotype was not. CONCLUSIONS Our results show that a single gene mutation can cause distinct seizure phenotypes through independent molecular mechanisms. A lack of effect of genetic background on thermal seizure susceptibility is consistent with the higher penetrance of febrile seizures compared to absence seizures seen in family members with the mutation. These mouse studies help to provide a conceptual framework within which clinical heterogeneity seen in genetic epilepsy can be explained.
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Affiliation(s)
- Christopher A Reid
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Australia.
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Shen Q, Fuchs T, Sahir N, Luscher B. GABAergic control of critical developmental periods for anxiety- and depression-related behavior in mice. PLoS One 2012; 7:e47441. [PMID: 23071808 PMCID: PMC3469546 DOI: 10.1371/journal.pone.0047441] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Accepted: 09/17/2012] [Indexed: 01/04/2023] Open
Abstract
Vulnerability for anxiety and depressive disorders is thought to have origins in early life and is increasingly recognized to involve deficits in GABAergic neurotransmission. Mice that were rendered heterozygous for the γ2 subunit gene of GABA(A) receptors (GABA(A)Rs) show behavioral, cognitive, neuroendocrine and pharmacologic features expected of a mouse model of melancholic anxious depression, including reduced survival of adult-born hippocampal neurons. Here we embarked on elucidating the developmental substrate underlying this phenotype, focusing on the Elevated Plus Maze and Forced Swim Test as relevant behavioral paradigms. In a first series of experiments using hemizygous tamoxifen-induced genetic inactivation of a floxed γ2 genomic locus we show that reducing the gene dosage at postnatal days (P)13/14 but not P27/28 results in altered behavior in both of these tests in adulthood, reminiscent of the anxious-depressive phenotype previously described for global heterozygous mice. However, in contrast to global heterozygous mice, the behavioral changes induced by γ2 subunit knockdown at P13/14 occurred without changes in adult hippocampal neurogenesis, indicating that altered neurogenesis is not an absolute prerequisite for anxiety- and depression-related behavior in this model. In a separate series of experiments using a pharmacological approach, acute but transient potentiation of GABA(A)Rs with diazepam uncovered distinct developmental vulnerabilities for altered behavior in the Elevated Plus Maze and Forced Swim Test, respectively. Specifically, diazepam given during P10-16 but not during later weeks resulted in increased anxiety-like behavior in adulthood, while diazepam administered during P29-35 but not earlier nor later resulted in increased immobility behavior in adulthood. We conclude that anxiety-like behavior in the Elevated Plus Maze and behavioral despair-like immobility in the Forced Swim Test are controlled by separate postnatal critical periods characterized by distinct developmental sensitivity to manipulation of GABAergic transmission via γ2 subunit-containing GABA(A)Rs.
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Affiliation(s)
- Qiuying Shen
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Thomas Fuchs
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Nadia Sahir
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Psychiatry, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania, United States of America
- Center for Molecular Investigation of Neurological Disorders, Pennsylvania State University, University Park, Pennsylvania, United States of America
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20
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Wu X, Wu Z, Ning G, Guo Y, Ali R, Macdonald RL, De Blas AL, Luscher B, Chen G. γ-Aminobutyric acid type A (GABAA) receptor α subunits play a direct role in synaptic versus extrasynaptic targeting. J Biol Chem 2012; 287:27417-30. [PMID: 22711532 DOI: 10.1074/jbc.m112.360461] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GABA(A) receptors (GABA(A)-Rs) are localized at both synaptic and extrasynaptic sites, mediating phasic and tonic inhibition, respectively. Previous studies suggest an important role of γ2 and δ subunits in synaptic versus extrasynaptic targeting of GABA(A)-Rs. Here, we demonstrate differential function of α2 and α6 subunits in guiding the localization of GABA(A)-Rs. To study the targeting of specific subtypes of GABA(A)-Rs, we used a molecularly engineered GABAergic synapse model to precisely control the GABA(A)-R subunit composition. We found that in neuron-HEK cell heterosynapses, GABAergic events mediated by α2β3γ2 receptors were very fast (rise time ∼2 ms), whereas events mediated by α6β3δ receptors were very slow (rise time ∼20 ms). Such an order of magnitude difference in rise time could not be attributed to the minute differences in receptor kinetics. Interestingly, synaptic events mediated by α6β3 or α6β3γ2 receptors were significantly slower than those mediated by α2β3 or α2β3γ2 receptors, suggesting a differential role of α subunit in receptor targeting. This was confirmed by differential targeting of the same δ-γ2 chimeric subunits to synaptic or extrasynaptic sites, depending on whether it was co-assembled with the α2 or α6 subunit. In addition, insertion of a gephyrin-binding site into the intracellular domain of α6 and δ subunits brought α6β3δ receptors closer to synaptic sites. Therefore, the α subunits, together with the γ2 and δ subunits, play a critical role in governing synaptic versus extrasynaptic targeting of GABA(A)-Rs, possibly through differential interactions with gephyrin.
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Affiliation(s)
- Xia Wu
- Department of Biology, Huck Institutes of Life Sciences, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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21
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Abstract
Proper developmental, neural cell-type-specific, and activity-dependent regulation of GABAergic transmission is essential for virtually all aspects of CNS function. The number of GABA(A) receptors in the postsynaptic membrane directly controls the efficacy of GABAergic synaptic transmission. Thus, regulated trafficking of GABA(A) receptors is essential for understanding brain function in both health and disease. Here we summarize recent progress in the understanding of mechanisms that allow dynamic adaptation of cell surface expression and postsynaptic accumulation and function of GABA(A) receptors. This includes activity-dependent and cell-type-specific changes in subunit gene expression, assembly of subunits into receptors, as well as exocytosis, endocytic recycling, diffusion dynamics, and degradation of GABA(A) receptors. In particular, we focus on the roles of receptor-interacting proteins, scaffold proteins, synaptic adhesion proteins, and enzymes that regulate the trafficking and function of receptors and associated proteins. In addition, we review neuropeptide signaling pathways that affect neural excitability through changes in GABA(A)R trafficking.
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Affiliation(s)
- Bernhard Luscher
- Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
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22
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Luscher B, Shen Q. Gamma-aminobutyric acidergic deficits cause melancholic depression: a reply to Markou and Geyer. Biol Psychiatry 2011; 69:e13-4; author reply e15-6. [PMID: 21126731 DOI: 10.1016/j.biopsych.2010.09.054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 09/15/2010] [Indexed: 12/30/2022]
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23
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Shen Q, Lal R, Luellen BA, Earnheart JC, Andrews AM, Luscher B. gamma-Aminobutyric acid-type A receptor deficits cause hypothalamic-pituitary-adrenal axis hyperactivity and antidepressant drug sensitivity reminiscent of melancholic forms of depression. Biol Psychiatry 2010; 68:512-20. [PMID: 20579975 PMCID: PMC2930197 DOI: 10.1016/j.biopsych.2010.04.024] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 04/16/2010] [Accepted: 04/18/2010] [Indexed: 12/27/2022]
Abstract
BACKGROUND The gamma-aminobutyric acid (GABA) Type A receptor deficits that are induced by global or forebrain-specific heterozygous inactivation of the gamma2 subunit gene in mouse embryos result in behavior indicative of trait anxiety and depressive states. By contrast, a comparable deficit that is delayed to adolescence is without these behavioral consequences. Here we characterized gamma2-deficient mice with respect to hypothalamic-pituitary-adrenal (HPA) axis abnormalities and antidepressant drug responses. METHODS We analyzed the behavioral responses of gamma2(+/-) mice to desipramine and fluoxetine in novelty suppressed feeding, forced swim, tail suspension, and sucrose consumption tests as well as GABA(A) receptor deficit- and antidepressant drug treatment-induced alterations in serum corticosterone. RESULTS Baseline corticosterone concentrations in adult gamma2-deficient mice were elevated independent of whether the genetic lesion was induced during embryogenesis or delayed to adolescence. However, the manifestation of anxious-depressive behavior in different gamma2-deficient mouse lines was correlated with early onset HPA axis hyperactivity during postnatal development. Chronic but not subchronic treatment of gamma2(+/-) mice with fluoxetine or desipramine normalized anxiety-like behavior in the novelty suppressed feeding test. Moreover, desipramine had antidepressant-like effects in that it normalized HPA axis function and depression-related behavior of gamma2(+/-) mice in the forced swim, tail suspension, and sucrose consumption tests. By contrast, fluoxetine was ineffective as an antidepressant and failed to normalize HPA axis function. CONCLUSIONS Developmental deficits in GABAergic inhibition in the forebrain cause behavioral and endocrine abnormalities and selective antidepressant drug responsiveness indicative of anxious-depressive disorders such as melancholic depression, which are frequently characterized by HPA axis hyperactivity and greater efficacy of desipramine versus fluoxetine.
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Affiliation(s)
- Qiuying Shen
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Rachnanjali Lal
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - Beth A. Luellen
- Department of Biology, Pennsylvania State University, University Park, PA 16802
| | - John C. Earnheart
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Anne Milasincic Andrews
- Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, PA 16802, Department of Chemistry, Pennsylvania State University, University Park, PA 16802, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802
| | - Bernhard Luscher
- Department of Biochemistry & Molecular Biology, Pennsylvania State University, University Park, PA 16802, Department of Biology, Pennsylvania State University, University Park, PA 16802, Department of Psychiatry, Pennsylvania State University, College of Medicine, Hershey, PA 17033, Corresponding Author: Bernhard Luscher, Ph. D., Department of Biology Penn State University 301 Life Sciences Building University Park, PA 16801 Phone office: 814-865 5549 Phone lab: 814-865 5563
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24
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Yuan X, Yao J, Norris D, Tran DD, Bram RJ, Chen G, Luscher B. Calcium-modulating cyclophilin ligand regulates membrane trafficking of postsynaptic GABA(A) receptors. Mol Cell Neurosci 2008; 38:277-89. [PMID: 18424167 DOI: 10.1016/j.mcn.2008.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Revised: 02/23/2008] [Accepted: 03/01/2008] [Indexed: 10/22/2022] Open
Abstract
Accumulation of GABA(A) receptors (GABA(A)Rs) at GABAergic synapses requires the cytoplasmic loop region and C-terminal transmembrane domain of the receptor gamma2 subunit. We here report a novel interaction of gamma2 with Calcium-Modulating cyclophilin Ligand (CAML), an integral membrane protein that regulates this mechanism. Interaction of GABA(A)Rs with CAML depends on both the cytoplasmic region and fourth transmembrane domain of the gamma2 subunit, CAML immunoprecipitates with GABA(A)Rs from transfected cells and brain lysates and colocalizes with gamma2 in ER vesicles in soma and dendrites of neurons. CAML shRNA treatment results in reduced expression of postsynaptic GABA(A)Rs, along with significant reductions in GABA-evoked whole cell currents and GABAergic synaptic function, while glutamatergic transmission is unaffected. Reduced surface expression of GABA(A)Rs in CAML mutant neurons is associated with selective deficits in recycling of endocytosed GABA(A)Rs to the cell surface. Our results indicate a specific role of CAML in functional expression and endocytic recycling of postsynaptic GABA(A)Rs.
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Affiliation(s)
- Xu Yuan
- Department of Biology, Penn State University, Life Sciences Building, University Park, PA 16802, USA
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25
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Deng L, Yao J, Fang C, Dong N, Luscher B, Chen G. Sequential postsynaptic maturation governs the temporal order of GABAergic and glutamatergic synaptogenesis in rat embryonic cultures. J Neurosci 2007; 27:10860-9. [PMID: 17913919 PMCID: PMC6672810 DOI: 10.1523/jneurosci.2744-07.2007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sequential formation of GABAergic and glutamatergic synapses is thought to be crucial for constructing the stereotypic neural networks during brain development. However, why GABAergic synapses are formed earlier than glutamatergic synapses in the developing brain is not well understood. We used electrophysiology and fluorescence imaging to study GABAergic and glutamatergic synaptogenesis in embryonic hypothalamic cultures, which contain approximately 40% GABAergic and approximately 60% glutamatergic neurons. The newly dissociated embryonic hypothalamic neurons contained a significant pool of functional GABA(A) receptors but a very low level of glutamate receptors. Within the first week of culture, the time course of GABAergic synaptogenesis in embryonic neurons coincided with that of presynaptic vesicle cycling, but both measurements lagged behind the detection of functional GABA(A) receptors. Remarkably, the GABA(A) receptors of newly dissociated embryonic neurons can be rapidly clustered into postsynaptic apparatus and generate functional synaptic currents within 4-6 h when cocultured with mature neurons. Consistent with earlier expression of GABA(A) receptors in immature neurons, synaptic GABAergic events were always detected before the onset of glutamatergic events in both purely embryonic and heterochronic cultures. Interestingly, overexpression of glutamate receptors in embryonic neurons not only increased whole-cell glutamate currents but also significantly increased the frequency of excitatory synaptic events. We conclude that the sequential formation of GABAergic and glutamatergic synapses in immature neurons is likely governed by a sequential expression of GABA(A) and glutamate receptors during neuronal development.
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Affiliation(s)
- Lunbin Deng
- Department of Biology
- The Huck Institutes of Life Sciences
| | - Jun Yao
- Department of Biology
- The Huck Institutes of Life Sciences
| | - Cheng Fang
- Department of Biology
- The Huck Institutes of Life Sciences
- Department of Biochemistry and Molecular Biology, and
| | - Ning Dong
- Department of Biology
- The Huck Institutes of Life Sciences
| | - Bernhard Luscher
- Department of Biology
- The Huck Institutes of Life Sciences
- Department of Biochemistry and Molecular Biology, and
- Department of Psychiatry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Gong Chen
- Department of Biology
- The Huck Institutes of Life Sciences
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26
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Abstract
A number of cancers are characterized by elevated expression of CK2 (formerly casein kinase II), which has been implicated as a key component in cell proliferation and transformation. Two lines of evidence, (a) deregulated expression of CK2 and (b) CK2beta ubiquitination and degradation of these in a proteasome-dependent manner prompted further investigation of the regulation of CK2beta protein stability. We demonstrate that mutating six surface-exposed lysine residues to arginine (6KR) to interfere with ubiquitin attachment can stabilize CK2beta. Examination of 6KR expression in cells revealed increased stability over time and increased its steady-state expression level compared with CK2beta. In cells, 6KR was no longer sensitive to proteasome inhibition but maintained an elevated expression level. In our studies, 6KR functioned as a normal CK2 regulatory subunit, because it participated in CK2beta dimerization, associated with catalytic subunits, was autophosphorylated, and formed active, stable CK2 tetramers. The physiological role of CK2beta stabilization was investigated in cell proliferation assays, which showed a significant decrease in proliferation in cells expressing 6KR compared with CK2beta. Overall, our results indicate that a stabilized form of CK2beta can be used to inhibit cell proliferation.
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Affiliation(s)
- Ashley C French
- Regulatory Biology and Functional Genomics Research Group, Siebens-Drake Medical Research Institute, Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
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27
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Abstract
Deficits in GABAergic inhibitory transmission are a hallmark of temporal lobe epilepsy and have been replicated in animal and tissue culture models of epilepsy. GABAergic inhibition comprises phasic and tonic inhibition that is mediated by synaptic and extrasynaptic GABAA receptors, respectively. We have recently demonstrated that chronic stimulation with cyclothiazide (CTZ) or kainic acid (KA) induces robust epileptiform activity in hippocampal neurons both in vitro and in vivo. Here, we report a downregulation of tonic GABA inhibition after chronic epileptogenic stimulation of rat hippocampal cultures. Chronic pretreatment of hippocampal neurons with CTZ or KA resulted in a marked reduction in GABAergic inhibition, as shown by a significant decrease in whole-cell GABA currents and in the frequency of miniature inhibitory postsynaptic currents (mIPSCs). Interestingly, synaptically localized GABAA receptors remained relatively stable, as evidenced by the unaltered amplitude of mIPSCs, as well as the unchanged punctate immunoreactivity of gamma2 subunit-containing postsynaptic GABAA receptors. In contrast, tonic GABA currents, assessed either by a GABAA receptor antagonist bicuculline or a selective extrasynaptic GABAA receptor agonist THIP, were significantly reduced following epileptogenic stimulation. These results reveal a novel form of neural plasticity, that epileptogenic stimulation can selectively downregulate extrasynaptic GABAA receptors while leaving synaptic GABAA receptors unchanged. Thus, in addition to synaptic alteration of GABAergic transmission, regulation of tonic inhibition may also play an important role during epileptogenesis.
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Affiliation(s)
- Jin-shun Qi
- Department of Biology, 201 Life Sciences Building, Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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28
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Pannell C, Simonian SX, Gillies GE, Luscher B, Herbison AE. Hypothalamic somatostatin and growth hormone-releasing hormone mRNA expression depend upon GABA(A) receptor expression in the developing mouse. Neuroendocrinology 2002; 76:93-8. [PMID: 12169770 DOI: 10.1159/000064428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Gonadal steroids exert an important regulatory influence upon the biosynthetic and secretory activity of the somatostatin and growth hormone-releasing hormone (GHRH) neurons controlling the release of growth hormone. It is hypothesized that some of these effects occur in an indirect transsynaptic manner through the steroid regulation of GAGAergic inputs to these cells. Using GABA(A) receptor gamma(2) subunit knockout mice (gamma(2)(-/-)), which exhibit marked deficiencies in GABA(A) receptor functioning, we have examined here whether signaling through the GABA(A) receptor has any role in maintaining normal levels of somatostatin and GHRH mRNA expression in vivo. In situ hybridization experiments using (35)S-labeled oligonucleotide probes revealed that cellular levels of somatostatin mRNA in the periventricular nucleus were significantly (p < 0.01) reduced by 16% in newborn gamma(2)(-/-) mice compared with wild-type litter mates (gamma(2)(+/+)). Somatostatin mRNA expression in the striatum was not changed. Cellular levels of GHRH mRNA expression in the arcuate nucleus were significantly (p < 0.05) reduced by 30% in gamma(2)(-/-) compared with gamma(2)(+/+) mice. These results demonstrate that deletion of the gamma(2) subunit of the GABA(A) receptor reduces somatostatin and GHRH mRNA expression within the hypothalamopituitary axis and indicate that GABA exerts a tonic stimulatory influence upon both somatostatin and GHRH biosynthesis in vivo in the neonatal mouse.
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Affiliation(s)
- Catherine Pannell
- Laboratory of Neuroendocrinology, The Babraham Institute, Babraham, Cambridge, UK
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29
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Simonian SX, Skynner MJ, Sieghart W, Essrich C, Luscher B, Herbison AE. Role of the GABA(A) receptor gamma2 subunit in the development of gonadotropin-releasing hormone neurons in vivo. Eur J Neurosci 2000; 12:3488-96. [PMID: 11029618 DOI: 10.1046/j.1460-9568.2000.00225.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have employed transgenic mouse models to examine the functional significance of the gamma2 subunit of the GABA(A) (gamma-aminobutyric acid) receptor to the correct development of gonadotropin-releasing hormone (GnRH) neurons in vivo. In the first experiment, the expression of gamma2 subunit protein by the GnRH phenotype was determined using transgenic mice in which GnRH gene sequences direct the expression of the LacZ reporter to the nucleus of the GnRH neurons. This greatly facilitates the immunocytochemical identification of non-nuclear-located antigens within GnRH neurons and revealed that approximately 25% of juvenile GnRH neurons were immunoreactive for the gamma2 subunit and that this increased to 40% in pubertal mice. In the second experiment, GnRH mRNA expression was examined in the brains of gamma2 subunit knockout mice (gamma2(0/0)) and their wild-type (gamma2+/+) littermates at embryonic day 15 and postnatal days (P) 0 and 11-16 using in situ hybridization. The distribution and numbers of cells expressing GnRH mRNA in gamma2+/+ and gamma2(0/0) mice were not found to differ at any age. However, the GnRH mRNA content of medial septal cells was significantly lower in gamma2(0/0) compared with gamma2+/+ mice at P11-16 (P<0.05) and the same trend was observed for preoptic area neurons. These results demonstrate that while the gamma2 subunit of the GABA(A) receptor is expressed by postnatal GnRH neurons, their embryonic development does not require a functional gamma2 subunit. In contrast, postnatal GnRH mRNA expression was found to be dependent upon signalling through the GABA(A) receptor.
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MESH Headings
- Animals
- Cell Count
- Female
- Fetus
- Genes, Reporter/genetics
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Hypothalamus, Anterior/cytology
- Hypothalamus, Anterior/metabolism
- Lac Operon/genetics
- Mice
- Mice, Knockout/genetics
- Mice, Knockout/metabolism
- Mice, Transgenic/genetics
- Mice, Transgenic/metabolism
- Neurons/cytology
- Neurons/metabolism
- Phenotype
- Preoptic Area/cytology
- Preoptic Area/metabolism
- Prosencephalon/cytology
- Prosencephalon/embryology
- Prosencephalon/metabolism
- RNA, Messenger/metabolism
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Septal Nuclei/cytology
- Septal Nuclei/metabolism
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Affiliation(s)
- S X Simonian
- Laboratory of Neuroendocrinology, The Babraham Institute, Babraham, Cambridge, UK
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30
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Abstract
1. The aim of this study was to define the biophysical properties contributed by the gamma2 subunit to native single GABAA receptors. 2. Single-channel activity was recorded from neurones of wild-type (gamma2+/+) mice and compared with that from mice which were heterozygous (gamma2+/-) or homozygous (gamma2-/-) for a targeted disruption in the gamma2 subunit gene of the GABAA receptor. Unitary currents were evoked by low concentrations of GABA (0.5-5 microM) in membrane patches from acutely isolated dorsal root ganglion (DRG) neurones (postnatal day 0) and by 1 microM GABA in patches from embryonic hippocampal neurones which were cultured for up to 3 weeks. 3. GABAA receptors from DRG and hippocampal neurones of gamma2+/+ and gamma2+/- mice displayed predominantly a conductance state of 28 pS and less frequently 18 and 12 pS states. In gamma2-/- mice, conductance states mainly of 12 pS and less frequently of 24 pS were found. 4. The mean open duration of the 28 pS state in gamma2+/+ GABAA receptors (1.5-2.6 ms) was substantially longer than for the 12 pS state of gamma2-/- GABAA receptors (0.9-1.2 ms) at all GABA concentrations. For gamma2+/+ and gamma2-/- channels, the mean open duration was increased at higher GABA concentrations. 5. Open duration frequency distributions of 28 and 12 pS receptors revealed the existence of at least three exponential components. Components with short mean durations declined and components with long mean durations increased in relative frequency at higher GABA concentration indicating at least two binding sites of GABA per 28 and 12 pS receptor. 6. Shut time frequency distributions revealed at least four exponential components of which two were identified as intraburst components in 28 pS and one in 12 pS GABAA receptors. 7. The mean burst duration and the mean number of openings per burst increased in 28 and 12 pS GABAA receptors with increasing GABA concentration. At least two burst types were identified: simple bursts consisting of single openings and complex bursts of five to six openings in 28 pS but only two to three openings in 12 pS GABAA receptors. 8. We conclude that the gamma2 subunit enhances the efficacy of GABA by determining open conformations of high conductance and long lifetime, and by prolonging the time receptors remain in the activated bursting state.
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MESH Headings
- Animals
- Animals, Newborn
- Cells, Cultured
- Electric Conductivity
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiology
- Hippocampus/metabolism
- Hippocampus/physiology
- Ion Channel Gating
- Ion Channels/metabolism
- Kinetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Neurons/metabolism
- Neurons/physiology
- Patch-Clamp Techniques
- Protein Structure, Quaternary
- Receptors, GABA-A/chemistry
- Receptors, GABA-A/genetics
- Receptors, GABA-A/physiology
- gamma-Aminobutyric Acid/pharmacology
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Affiliation(s)
- M Lorez
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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31
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Abstract
The rules governing the assembly of GABA(A) receptors in vivo were assessed in subunit mutant mice. The transcription of individual subunit genes was regulated independently. The lack of a particular subunit did not result in a molecular rescue by an enhanced transcription of other subunits. In addition, the availability of an alpha- and beta-subunit was essential for receptor formation. Finally, highly selective recognition processes directed the subcellular targeting of receptors. The loss of a particular receptor subtype (alpha5) did not lead to a subcellular redistribution of the remaining subtype (alpha2) present in the same cell.
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Affiliation(s)
- H Mohler
- Institute of Pharmacology, Federal Institute of Technology (ETH) and University of Zürich, Switzerland
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32
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Fritschy JM, Brandner S, Aguzzi A, Koedood M, Luscher B, Mitchell PJ. Brain cell type specificity and gliosis-induced activation of the human cytomegalovirus immediate-early promoter in transgenic mice. J Neurosci 1996; 16:2275-82. [PMID: 8601807 PMCID: PMC6578536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Human cytomegalovirus (HCMV) can cause debilitating, sometimes fatal, opportunistic infections in congenitally infected infants and in immunodeficient individuals such as patients with the acquired immunodeficiency syndrome (AIDS). Molecular mechanisms that determine cell type specificity of HCMV infection and latency are poorly understood. We recently described a transgenic mouse model for analysis of HCMV major immediate-early (IE) promoter regulation and showed that sites of IE promoter activity during murine embryogenesis correlate with known target tissues of congenital HCMV infection in human fetuses (Koedood et al., 1995). Among various permissive human tissues, the brain is a site where HCMV infections can be devastating. Here, we have used immunohistochemical double-labeling analysis to identify specific cell types with HCMV-IE promoter activity in brains of transgenic mice at several postnatal stages. IE promoter activity was restricted to some endothelial cells, ependymal cells, choroid plexus epithelia, and neurons at discrete locations in the forebrain, brainstem, and cerebellum. Endothelial cells and neurons with activity were proportionately more abundant in neonatal than in adult brains. Although the IE promoter was normally silent in most astrocytes, activity was strongly induced in reactive astrocytes in response to a neocortical stab lesion. The findings support a model, consistent with clinical literature on HCMV encephalitis, whereby tissue damage and gliosis caused by HCMV infection of endothelial and ependymal cells progressively renders adjacent permissive neurons and reactive astrocytes accessible to infection. This transgenic model system should facilitate identification of factors that regulate the HCMV IE promoter with regard to infection permissivity and reactivation from latency.
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Affiliation(s)
- J M Fritschy
- Institutes of Molecular Biology, University of Zurich, CH-8057 Zurich, Switzerland
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