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Campbell BFN, Cruz-Ochoa N, Otomo K, Lukacsovich D, Espinosa P, Abegg A, Luo W, Bellone C, Földy C, Tyagarajan SK. Gephyrin phosphorylation facilitates sexually dimorphic development and function of parvalbumin interneurons in the mouse hippocampus. Mol Psychiatry 2024:10.1038/s41380-024-02517-5. [PMID: 38503929 DOI: 10.1038/s41380-024-02517-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 02/25/2024] [Accepted: 03/04/2024] [Indexed: 03/21/2024]
Abstract
The precise function of specialized GABAergic interneuron subtypes is required to provide appropriate synaptic inhibition for regulating principal neuron excitability and synchronization within brain circuits. Of these, parvalbumin-type (PV neuron) dysfunction is a feature of several sex-biased psychiatric and brain disorders, although, the underlying developmental mechanisms are unclear. While the transcriptional action of sex hormones generates sexual dimorphism during brain development, whether kinase signaling contributes to sex differences in PV neuron function remains unexplored. In the hippocampus, we report that gephyrin, the main inhibitory post-synaptic scaffolding protein, is phosphorylated at serine S268 and S270 in a developmentally-dependent manner in both males and females. When examining GphnS268A/S270A mice in which site-specific phosphorylation is constitutively blocked, we found that sex differences in PV neuron density in the hippocampal CA1 present in WT mice were abolished, coincident with a female-specific increase in PV neuron-derived terminals and increased inhibitory input onto principal cells. Electrophysiological analysis of CA1 PV neurons indicated that gephyrin phosphorylation is required for sexually dimorphic function. Moreover, while male and female WT mice showed no difference in hippocampus-dependent memory tasks, GphnS268A/S270A mice exhibited sex- and task-specific deficits, indicating that gephyrin phosphorylation is differentially required by males and females for convergent cognitive function. In fate mapping experiments, we uncovered that gephyrin phosphorylation at S268 and S270 establishes sex differences in putative PV neuron density during early postnatal development. Furthermore, patch-sequencing of putative PV neurons at postnatal day 4 revealed that gephyrin phosphorylation contributes to sex differences in the transcriptomic profile of developing interneurons. Therefore, these early shifts in male-female interneuron development may drive adult sex differences in PV neuron function and connectivity. Our results identify gephyrin phosphorylation as a new substrate organizing PV neuron development at the anatomical, functional, and transcriptional levels in a sex-dependent manner, thus implicating kinase signaling disruption as a new mechanism contributing to the sex-dependent etiology of brain disorders.
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Affiliation(s)
- Benjamin F N Campbell
- Institute of Pharmacology and Toxicology, University of Zürich, 8057, Zürich, Switzerland
| | - Natalia Cruz-Ochoa
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, 8057, Zürich, Switzerland
- Adaptive Brain Circuits in Development and Learning (AdaBD), University Research Priority Program (URPP), University of Zürich, 8057, Zürich, Switzerland
| | - Kanako Otomo
- Institute of Pharmacology and Toxicology, University of Zürich, 8057, Zürich, Switzerland
| | - David Lukacsovich
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, 8057, Zürich, Switzerland
| | - Pedro Espinosa
- Department of Basic Neuroscience, University of Geneva, 1211, Geneva, Switzerland
| | - Andrin Abegg
- Institute of Pharmacology and Toxicology, University of Zürich, 8057, Zürich, Switzerland
| | - Wenshu Luo
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, 8057, Zürich, Switzerland
| | - Camilla Bellone
- Department of Basic Neuroscience, University of Geneva, 1211, Geneva, Switzerland
| | - Csaba Földy
- Laboratory of Neural Connectivity, Brain Research Institute, Faculties of Medicine and Science, University of Zürich, 8057, Zürich, Switzerland
- Adaptive Brain Circuits in Development and Learning (AdaBD), University Research Priority Program (URPP), University of Zürich, 8057, Zürich, Switzerland
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zürich, 8057, Zürich, Switzerland.
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2
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Jung H, Kim S, Ko J, Um JW. Intracellular signaling mechanisms that shape postsynaptic GABAergic synapses. Curr Opin Neurobiol 2023; 81:102728. [PMID: 37236068 DOI: 10.1016/j.conb.2023.102728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023]
Abstract
Postsynaptic GABAergic receptors interact with various membrane and intracellular proteins to mediate inhibitory synaptic transmission. They form structural and/or signaling synaptic protein complexes that perform a variety of postsynaptic functions. In particular, the key GABAergic synaptic scaffold, gephyrin, and its interacting partners govern downstream signaling pathways that are essential for GABAergic synapse development, transmission, and plasticity. In this review, we discuss recent researches on GABAergic synaptic signaling pathways. We also outline the main outstanding issues that need to be addressed in this field and highlight the association of dysregulated GABAergic synaptic signaling with the onset of various brain disorders.
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Affiliation(s)
- Hyeji Jung
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea
| | - Seungjoon Kim
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea; Center for Synapse Diversity and Specificity, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea
| | - Jaewon Ko
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea; Center for Synapse Diversity and Specificity, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea
| | - Ji Won Um
- Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea; Center for Synapse Diversity and Specificity, DGIST, 333 Techno Jungangdae-Ro, Hyeonpoong-Eup, Dalseong-Gun, Daegu 42988, South Korea.
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3
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Khayenko V, Schulte C, Reis SL, Avraham O, Schietroma C, Worschech R, Nordblom NF, Kachler S, Villmann C, Heinze KG, Schlosser A, Schueler‐Furman O, Tovote P, Specht CG, Maric HM. A Versatile Synthetic Affinity Probe Reveals Inhibitory Synapse Ultrastructure and Brain Connectivity**. Angew Chem Int Ed Engl 2022; 61:e202202078. [PMID: 35421279 PMCID: PMC9400903 DOI: 10.1002/anie.202202078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Indexed: 11/10/2022]
Abstract
Visualization of inhibitory synapses requires protocol tailoring for different sample types and imaging techniques, and usually relies on genetic manipulation or the use of antibodies that underperform in tissue immunofluorescence. Starting from an endogenous ligand of gephyrin, a universal marker of the inhibitory synapse, we developed a short peptidic binder and dimerized it, significantly increasing affinity and selectivity. We further tailored fluorophores to the binder, yielding “Sylite”—a probe with outstanding signal‐to‐background ratio that outperforms antibodies in tissue staining with rapid and efficient penetration, mitigation of staining artifacts, and simplified handling. In super‐resolution microscopy Sylite precisely localizes the inhibitory synapse and enables nanoscale measurements. Sylite profiles inhibitory inputs and synapse sizes of excitatory and inhibitory neurons in the midbrain and combined with complimentary tracing techniques reveals the synaptic connectivity.
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Affiliation(s)
- Vladimir Khayenko
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Clemens Schulte
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Sara L. Reis
- Institute of Clinical Neurobiology University Hospital Versbacher Str. 5 97078 Wuerzburg Germany
| | - Orly Avraham
- Department of Microbiology and Molecular Genetics Institute for Medical Research Israel-Canada the Hebrew University Hadassah Medical School Jerusalem 91120 Israel
| | | | - Rafael Worschech
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Noah F. Nordblom
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Sonja Kachler
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Carmen Villmann
- Institute of Clinical Neurobiology University Hospital Versbacher Str. 5 97078 Wuerzburg Germany
| | - Katrin G. Heinze
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Andreas Schlosser
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
| | - Ora Schueler‐Furman
- Department of Microbiology and Molecular Genetics Institute for Medical Research Israel-Canada the Hebrew University Hadassah Medical School Jerusalem 91120 Israel
| | - Philip Tovote
- Institute of Clinical Neurobiology University Hospital Versbacher Str. 5 97078 Wuerzburg Germany
- Center of Mental Health University of Wuerzburg Margarete-Höppel-Platz 1 97080 Wuerzburg Germany
| | - Christian G. Specht
- Diseases and Hormones of the Nervous System (DHNS) Inserm U1195 Université Paris-Saclay 80 rue du Général Leclerc 94276 Le Kremlin-Bicêtre France
| | - Hans M. Maric
- Rudolf Virchow Center Center for Integrative and Translational Bioimaging; University of Wuerzburg Josef-Schneider-Str. 2 97080 Wuerzburg Germany
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Khayenko V, Schulte C, Reis SL, Avraham O, Schietroma C, Worschech R, Nordblom NF, Kachler S, Villmann C, Heinze KG, Schlosser A, Schueler-Furman O, Tovote P, Specht CG, Maric HM. A Versatile Synthetic Affinity Probe Reveals Inhibitory Synapse Ultrastructure and Brain Connectivity. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202202078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Vladimir Khayenko
- University of Wurzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center Josef-Schneider-Strasse. 2 97080 Würzburg GERMANY
| | - Clemens Schulte
- University of Wurzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center Josef-Schneider-Strasse. 2 97080 Würzburg GERMANY
| | - Sara L. Reis
- University Hospital Wurzburg: Universitatsklinikum Wurzburg Clinical Neurobiology Versbacherstr.5 97078 Würzburg GERMANY
| | - Orly Avraham
- The Hebrew University of Jerusalem Microbiology and Molecular Genetics ISRAEL
| | | | - Rafael Worschech
- University of Wurzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center GERMANY
| | - Noah F. Nordblom
- University of Würzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center GERMANY
| | - Sonja Kachler
- University of Würzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center GERMANY
| | - Carmen Villmann
- University Hospital Wurzburg: Universitatsklinikum Wurzburg Clinical Neurobiology GERMANY
| | - Katrin G. Heinze
- University of Würzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center GERMANY
| | - Andreas Schlosser
- University of Würzburg: Julius-Maximilians-Universitat Wurzburg Rudolf Virchow Center Rudolf Virchow Zentrum Gebäude D15Josef-Schneider-Strasse 2 97080 Würzburg GERMANY
| | - Ora Schueler-Furman
- The Hebrew University of Jerusalem Microbiology and Molecular Genetics ISRAEL
| | - Philip Tovote
- University of Würzburg: Julius-Maximilians-Universitat Wurzburg Clinical Neurobiology GERMANY
| | - Christian G. Specht
- INSERM U1195: Maladies et hormones du systeme nerveux NSERM U1195: Maladies et hormones du systeme nerveux FRANCE
| | - Hans Michael Maric
- University of Würzburg Biotechnology and Biophysics Rudolf Virchow Zentrum Gebäude D15Josef-Schneider-Strasse 2 97080 Würzburg GERMANY
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Servetti M, Pisciotta L, Tassano E, Cerminara M, Nobili L, Boeri S, Rosti G, Lerone M, Divizia MT, Ronchetto P, Puliti A. Neurodevelopmental Disorders in Patients With Complex Phenotypes and Potential Complex Genetic Basis Involving Non-Coding Genes, and Double CNVs. Front Genet 2021; 12:732002. [PMID: 34621295 PMCID: PMC8490884 DOI: 10.3389/fgene.2021.732002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 09/03/2021] [Indexed: 12/15/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) are a heterogeneous class of brain diseases, with a complex genetic basis estimated to account for up to 50% of cases. Nevertheless, genetic diagnostic yield is about 20%. Array-comparative genomic hybridization (array-CGH) is an established first-level diagnostic test able to detect pathogenic copy number variants (CNVs), however, most identified variants remain of uncertain significance (VUS). Failure of interpretation of VUSs may depend on various factors, including complexity of clinical phenotypes and inconsistency of genotype-phenotype correlations. Indeed, although most NDD-associated CNVs are de novo, transmission from unaffected parents to affected children of CNVs with high risk for NDDs has been observed. Moreover, variability of genetic components overlapped by CNVs, such as long non-coding genes, genomic regions with long-range effects, and additive effects of multiple CNVs can make CNV interpretation challenging. We report on 12 patients with complex phenotypes possibly explained by complex genetic mechanisms, including involvement of antisense genes and boundaries of topologically associating domains. Eight among the 12 patients carried two CNVs, either de novo or inherited, respectively, by each of their healthy parents, that could additively contribute to the patients’ phenotype. CNVs overlapped either known NDD-associated or novel candidate genes (PTPRD, BUD13, GLRA3, MIR4465, ABHD4, and WSCD2). Bioinformatic enrichment analyses showed that genes overlapped by the co-occurring CNVs have synergistic roles in biological processes fundamental in neurodevelopment. Double CNVs could concur in producing deleterious effects, according to a two-hit model, thus explaining the patients’ phenotypes and the incomplete penetrance, and variable expressivity, associated with the single variants. Overall, our findings could contribute to the knowledge on clinical and genetic diagnosis of complex forms of NDD.
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Affiliation(s)
- Martina Servetti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy.,Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Livia Pisciotta
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy.,Child Neuropsychiatry Unit, ASST Fatebenefratelli Sacco, Milano, Italy
| | - Elisa Tassano
- Human Genetics Laboratory, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Maria Cerminara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy
| | - Lino Nobili
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy.,Child Neuropsychiatry Unit, Istituto Giannina Gaslini, Genoa, Italy
| | - Silvia Boeri
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy.,Child Neuropsychiatry Unit, Istituto Giannina Gaslini, Genoa, Italy
| | - Giulia Rosti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy
| | - Margherita Lerone
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | | | - Patrizia Ronchetto
- Human Genetics Laboratory, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Aldamaria Puliti
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DiNOGMI), University of Genoa, Genoa, Italy.,Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
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Macha A, Liebsch F, Fricke S, Hetsch F, Neuser F, Johannes L, Kress V, Djémié T, Santamaria-Araujo JA, Vilain C, Aeby A, Van Bogaert P, Dejanovic B, Weckhuysen S, Meier JC, Schwarz G. Bi-allelic gephyrin variants impair GABAergic inhibition in a patient with epileptic encephalopathy. Hum Mol Genet 2021; 31:901-913. [PMID: 34617111 DOI: 10.1093/hmg/ddab298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 09/10/2021] [Accepted: 09/22/2021] [Indexed: 11/12/2022] Open
Abstract
Synaptic inhibition is essential for shaping the dynamics of neuronal networks, and aberrant inhibition is linked to epilepsy. Gephyrin (Geph) is the principal scaffolding protein at inhibitory synapses and is essential for postsynaptic clustering of glycine (GlyRs) and GABA type A receptors (GABAARs). Consequently, gephyrin is crucial for maintaining the relationship between excitation and inhibition in normal brain function and mutations in the gephyrin gene (GPHN) are associated with neurodevelopmental disorders and epilepsy. We identified bi-allelic variants in the GPHN gene, namely the missense mutation c.1264G > A and splice acceptor variant c.1315-2A > G, in a patient with developmental and epileptic encephalopathy (DEE). We demonstrate that the splice acceptor variant leads to nonsense-mediated mRNA decay (NMD). Furthermore, the missense variant (D422N) alters gephyrin structure, as examined by analytical size exclusion chromatography and CD-spectroscopy, thus leading to reduced receptor clustering and sensitivity towards calpain-mediated cleavage. Additionally, both alterations contribute to an observed reduction of inhibitory signal transmission in neurons, which likely contributes to the pathological encephalopathy.
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Affiliation(s)
- Arthur Macha
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Filip Liebsch
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Steffen Fricke
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.,Institute for Pathophysiology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Florian Hetsch
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Franziska Neuser
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Lena Johannes
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Vanessa Kress
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Tania Djémié
- Applied & Translational Neurogenomics Group, VIB-Center for Molecular Genetics, VIB, Antwerp, Belgium
| | - Jose A Santamaria-Araujo
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Catheline Vilain
- Department of Genetics, Hôpital Universitaire des Enfants Reine Fabiola, ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Department of Genetics, Hôpital Erasme, ULB Center of Human Genetics, Université Libre de Bruxelles, Brussels, Belgium.,Interuniversity Institute of Bioinformatics in Brussels, Université Libre de Bruxelles, Brussels, Belgium
| | - Alec Aeby
- Pediatric Neurology, Queen Fabiola Children Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Patrick Van Bogaert
- Departement of Pediatric Neurology, CHU d'Angers, and Laboratoire Angevin de Recherche en Ingénierie des Systèmes (LARIS), Université d'Angers, France
| | - Borislav Dejanovic
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany
| | - Sarah Weckhuysen
- Applied & Translational Neurogenomics Group, VIB-Center for Molecular Genetics, VIB, Antwerp, Belgium.,Translational Neurosciences, Faculty of Medicine and Health Science, University of Antwerp, Antwerp, Belgium.,Neurology Department, University Hospital Antwerp, Antwerp, Belgium
| | - Jochen C Meier
- Division Cell Physiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Guenter Schwarz
- Institute of Biochemistry, Department of Chemistry, University of Cologne, 50674 Cologne, Germany.,Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany
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Kuljis DA, Micheva KD, Ray A, Wegner W, Bowman R, Madison DV, Willig KI, Barth AL. Gephyrin-Lacking PV Synapses on Neocortical Pyramidal Neurons. Int J Mol Sci 2021; 22:ijms221810032. [PMID: 34576197 PMCID: PMC8467468 DOI: 10.3390/ijms221810032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/01/2021] [Accepted: 09/07/2021] [Indexed: 11/26/2022] Open
Abstract
Gephyrin has long been thought of as a master regulator for inhibitory synapses, acting as a scaffold to organize γ-aminobutyric acid type A receptors (GABAARs) at the post-synaptic density. Accordingly, gephyrin immunostaining has been used as an indicator of inhibitory synapses; despite this, the pan-synaptic localization of gephyrin to specific classes of inhibitory synapses has not been demonstrated. Genetically encoded fibronectin intrabodies generated with mRNA display (FingRs) against gephyrin (Gephyrin.FingR) reliably label endogenous gephyrin, and can be tagged with fluorophores for comprehensive synaptic quantitation and monitoring. Here we investigated input- and target-specific localization of gephyrin at a defined class of inhibitory synapse, using Gephyrin.FingR proteins tagged with EGFP in brain tissue from transgenic mice. Parvalbumin-expressing (PV) neuron presynaptic boutons labeled using Cre- dependent synaptophysin-tdTomato were aligned with postsynaptic Gephyrin.FingR puncta. We discovered that more than one-third of PV boutons adjacent to neocortical pyramidal (Pyr) cell somas lack postsynaptic gephyrin labeling. This finding was confirmed using correlative fluorescence and electron microscopy. Our findings suggest some inhibitory synapses may lack gephyrin. Gephyrin-lacking synapses may play an important role in dynamically regulating cell activity under different physiological conditions.
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Affiliation(s)
- Dika A. Kuljis
- Center for the Neural Basis of Cognition, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (D.A.K.); (A.R.); (R.B.)
| | - Kristina D. Micheva
- Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, CA 94304, USA; (K.D.M.); (D.V.M.)
| | - Ajit Ray
- Center for the Neural Basis of Cognition, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (D.A.K.); (A.R.); (R.B.)
| | - Waja Wegner
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, 37075 Göttingen, Germany; (W.W.); (K.I.W.)
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Ryan Bowman
- Center for the Neural Basis of Cognition, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (D.A.K.); (A.R.); (R.B.)
| | - Daniel V. Madison
- Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, CA 94304, USA; (K.D.M.); (D.V.M.)
| | - Katrin I. Willig
- Optical Nanoscopy in Neuroscience, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, 37075 Göttingen, Germany; (W.W.); (K.I.W.)
- Max Planck Institute of Experimental Medicine, 37075 Göttingen, Germany
| | - Alison L. Barth
- Center for the Neural Basis of Cognition, Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA; (D.A.K.); (A.R.); (R.B.)
- Correspondence: ; Tel.: +1-412-268-1198
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