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Moore T. X centromeric drive may explain the prevalence of polycystic ovary syndrome and other conditions: Genomic structure of the human X chromosome pericentromeric region is consistent with meiotic drive associated with PCOS and other conditions. Bioessays 2024:e2400056. [PMID: 39072829 DOI: 10.1002/bies.202400056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 07/02/2024] [Accepted: 07/04/2024] [Indexed: 07/30/2024]
Abstract
X chromosome centromeric drive may explain the prevalence of polycystic ovary syndrome and contribute to oocyte aneuploidy, menopause, and other conditions. The mammalian X chromosome may be vulnerable to meiotic drive because of X inactivation in the female germline. The human X pericentromeric region contains genes potentially involved in meiotic mechanisms, including multiple SPIN1 and ZXDC paralogs. This is consistent with a multigenic drive system comprising differential modification of the active and inactive X chromosome centromeres in female primordial germ cells and preferential segregation of the previously inactivated X chromosome centromere to the polar body at meiosis I. The drive mechanism may explain differences in X chromosome regulation in the female germlines of the human and mouse and, based on the functions encoded by the genes in the region, the transmission of X pericentromeric genetic or epigenetic variants to progeny could contribute to preeclampsia, autism, and differences in sexual differentiation.
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Affiliation(s)
- Tom Moore
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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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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Bousgouni V, Inge O, Robertson D, Jones I, Clatworthy I, Bakal C. ARHGEF9 regulates melanoma morphogenesis in environments with diverse geometry and elasticity by promoting filopodial-driven adhesion. iScience 2022; 25:104795. [PMID: 36039362 PMCID: PMC9418690 DOI: 10.1016/j.isci.2022.104795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/27/2022] [Accepted: 07/14/2022] [Indexed: 11/17/2022] Open
Abstract
Rho GTP Exchange Factors (RhoGEFs) and Rho GTPase Activating Proteins (RhoGAPs) are large families of molecules that regulate shape determination in all eukaryotes. In pathologies such as melanoma, RhoGEF and RhoGAP activity underpins the ability of cells to invade tissues of varying elasticity. To identify RhoGEFs and RhoGAPs that regulate melanoma cell shape on soft and/or stiff materials, we performed genetic screens, in tandem with single-cell quantitative morphological analysis. We show that ARHGEF9/Collybistin (Cb) is essential for cell shape determination on both soft and stiff materials, and in cells embedded in 3D soft hydrogel. ARHGEF9 is required for melanoma cells to invade 3D matrices. Depletion of ARHGEF9 results in loss of tension at focal adhesions decreased cell-wide contractility, and the inability to stabilize protrusions. Taken together we show that ARHGEF9 promotes the formation of actin-rich filopodia, which serves to establish and stabilize adhesions and determine melanoma cell shape.
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Affiliation(s)
- Vicky Bousgouni
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Oliver Inge
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
- Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - David Robertson
- Division of Breast Cancer Research, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Ian Jones
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Innes Clatworthy
- Core Research Laboratories, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Chris Bakal
- Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
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Imam N, Choudhury S, Heinze KG, Schindelin H. Differential modulation of collybistin conformational dynamics by the closely related GTPases Cdc42 and TC10. Front Synaptic Neurosci 2022; 14:959875. [PMID: 35989712 PMCID: PMC9386560 DOI: 10.3389/fnsyn.2022.959875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 07/06/2022] [Indexed: 11/13/2022] Open
Abstract
Interneuronal synaptic transmission relies on the proper spatial organization of presynaptic neurotransmitter release and its reception on the postsynaptic side by cognate neurotransmitter receptors. Neurotransmitter receptors are incorporated into and arranged within the plasma membrane with the assistance of scaffolding and adaptor proteins. At inhibitory GABAergic postsynapses, collybistin, a neuronal adaptor protein, recruits the scaffolding protein gephyrin and interacts with various neuronal factors including cell adhesion proteins of the neuroligin family, the GABAA receptor α2-subunit and the closely related small GTPases Cdc42 and TC10 (RhoQ). Most collybistin splice variants harbor an N-terminal SH3 domain and exist in an autoinhibited/closed state. Cdc42 and TC10, despite sharing 67.4% amino acid sequence identity, interact differently with collybistin. Here, we delineate the molecular basis of the collybistin conformational activation induced by TC10 with the aid of recently developed collybistin FRET sensors. Time-resolved fluorescence-based FRET measurements reveal that TC10 binds to closed/inactive collybistin leading to relief of its autoinhibition, contrary to Cdc42, which only interacts with collybistin when forced into an open state by the introduction of mutations destabilizing the closed state of collybistin. Taken together, our data describe a TC10-driven signaling mechanism in which collybistin switches from its autoinhibited closed state to an open/active state.
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Affiliation(s)
- Nasir Imam
- Institute of Structural Biology, Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Susobhan Choudhury
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Katrin G. Heinze
- Molecular Microscopy, Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
- Katrin G. Heinze,
| | - Hermann Schindelin
- Institute of Structural Biology, Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
- *Correspondence: Hermann Schindelin,
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5
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Duman JG, Blanco FA, Cronkite CA, Ru Q, Erikson KC, Mulherkar S, Saifullah AB, Firozi K, Tolias KF. Rac-maninoff and Rho-vel: The symphony of Rho-GTPase signaling at excitatory synapses. Small GTPases 2022; 13:14-47. [PMID: 33955328 PMCID: PMC9707551 DOI: 10.1080/21541248.2021.1885264] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 01/15/2023] Open
Abstract
Synaptic connections between neurons are essential for every facet of human cognition and are thus regulated with extreme precision. Rho-family GTPases, molecular switches that cycle between an active GTP-bound state and an inactive GDP-bound state, comprise a critical feature of synaptic regulation. Rho-GTPases are exquisitely controlled by an extensive suite of activators (GEFs) and inhibitors (GAPs and GDIs) and interact with many different signalling pathways to fulfill their roles in orchestrating the development, maintenance, and plasticity of excitatory synapses of the central nervous system. Among the mechanisms that control Rho-GTPase activity and signalling are cell surface receptors, GEF/GAP complexes that tightly regulate single Rho-GTPase dynamics, GEF/GAP and GEF/GEF functional complexes that coordinate multiple Rho-family GTPase activities, effector positive feedback loops, and mutual antagonism of opposing Rho-GTPase pathways. These complex regulatory mechanisms are employed by the cells of the nervous system in almost every step of development, and prominently figure into the processes of synaptic plasticity that underlie learning and memory. Finally, misregulation of Rho-GTPases plays critical roles in responses to neuronal injury, such as traumatic brain injury and neuropathic pain, and in neurodevelopmental and neurodegenerative disorders, including intellectual disability, autism spectrum disorder, schizophrenia, and Alzheimer's Disease. Thus, decoding the mechanisms of Rho-GTPase regulation and function at excitatory synapses has great potential for combatting many of the biggest current challenges in mental health.
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Affiliation(s)
- Joseph G. Duman
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Francisco A. Blanco
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Integrative Molecular and Biomedical Science Graduate Program, Baylor College of Medicine, Houston, TX, USA
| | - Christopher A. Cronkite
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, TX, USA
| | - Qin Ru
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kelly C. Erikson
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Shalaka Mulherkar
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Ali Bin Saifullah
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Karen Firozi
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Kimberley F. Tolias
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
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6
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Selective Overexpression of Collybistin in Mouse Hippocampal Pyramidal Cells Enhances GABAergic Neurotransmission and Protects against PTZ-Induced Seizures. eNeuro 2021; 8:ENEURO.0561-20.2021. [PMID: 34083383 PMCID: PMC8281261 DOI: 10.1523/eneuro.0561-20.2021] [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: 12/27/2020] [Revised: 04/02/2021] [Accepted: 05/23/2021] [Indexed: 11/21/2022] Open
Abstract
Collybistin (CB) is a rho guanine exchange factor found at GABAergic and glycinergic postsynapses that interacts with the inhibitory scaffold protein, gephyrin, and induces accumulation of gephyrin and GABA type-A receptors (GABAARs) to the postsynapse. We have previously reported that the isoform without the src homology 3 (SH3) domain, CBSH3-, is particularly active in enhancing the GABAergic postsynapse in both cultured hippocampal neurons as well as in cortical pyramidal neurons after chronic in vivo expression in in utero electroporated (IUE) rats. Deficiency of CB in knock-out (KO) mice results in absence of gephyrin and gephyrin-dependent GABAARs at postsynaptic sites in several brain regions, including hippocampus. In the present study, we have generated an adeno-associated virus (AAV) that expresses CBSH3- in a cre-dependent manner. Using male and female VGLUT1-IRES-cre or VGAT-IRES-cre mice, we explore the effect of overexpression of CBSH3- in hippocampal pyramidal cells or hippocampal interneurons. The results show that: (1) the accumulation of gephyrin and GABAARs at inhibitory postsynapses in hippocampal pyramidal neurons or interneurons can be enhanced by CBSH3- overexpression; (2) overexpression of CBSH3- in hippocampal pyramidal cells can enhance the strength of inhibitory neurotransmission; and (3) these enhanced inhibitory synapses provide protection against pentylenetetrazole (PTZ)-induced seizures. The results indicate that this AAV vector carrying CBSH3- can be used for in vivo enhancement of GABAergic synaptic transmission in selected target neurons in the brain.
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Liaci C, Camera M, Caslini G, Rando S, Contino S, Romano V, Merlo GR. Neuronal Cytoskeleton in Intellectual Disability: From Systems Biology and Modeling to Therapeutic Opportunities. Int J Mol Sci 2021; 22:ijms22116167. [PMID: 34200511 PMCID: PMC8201358 DOI: 10.3390/ijms22116167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/25/2021] [Accepted: 06/04/2021] [Indexed: 02/06/2023] Open
Abstract
Intellectual disability (ID) is a pathological condition characterized by limited intellectual functioning and adaptive behaviors. It affects 1–3% of the worldwide population, and no pharmacological therapies are currently available. More than 1000 genes have been found mutated in ID patients pointing out that, despite the common phenotype, the genetic bases are highly heterogeneous and apparently unrelated. Bibliomic analysis reveals that ID genes converge onto a few biological modules, including cytoskeleton dynamics, whose regulation depends on Rho GTPases transduction. Genetic variants exert their effects at different levels in a hierarchical arrangement, starting from the molecular level and moving toward higher levels of organization, i.e., cell compartment and functions, circuits, cognition, and behavior. Thus, cytoskeleton alterations that have an impact on cell processes such as neuronal migration, neuritogenesis, and synaptic plasticity rebound on the overall establishment of an effective network and consequently on the cognitive phenotype. Systems biology (SB) approaches are more focused on the overall interconnected network rather than on individual genes, thus encouraging the design of therapies that aim to correct common dysregulated biological processes. This review summarizes current knowledge about cytoskeleton control in neurons and its relevance for the ID pathogenesis, exploiting in silico modeling and translating the implications of those findings into biomedical research.
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Affiliation(s)
- Carla Liaci
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Mattia Camera
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Giovanni Caslini
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Simona Rando
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
| | - Salvatore Contino
- Department of Engineering, University of Palermo, Viale delle Scienze Ed. 8, 90128 Palermo, Italy;
| | - Valentino Romano
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), University of Palermo, Viale delle Scienze Ed. 16, 90128 Palermo, Italy;
| | - Giorgio R. Merlo
- Department of Molecular Biotechnology and Health Sciences, University of Torino, Via Nizza 52, 10126 Torino, Italy; (C.L.); (M.C.); (G.C.); (S.R.)
- Correspondence: ; Tel.: +39-0116706449; Fax: +39-0116706432
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8
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George S, Chiou TT, Kanamalla K, De Blas AL. Recruitment of Plasma Membrane GABA-A Receptors by Submembranous Gephyrin/Collybistin Clusters. Cell Mol Neurobiol 2021; 42:1585-1604. [PMID: 33547626 DOI: 10.1007/s10571-021-01050-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 01/23/2021] [Indexed: 11/29/2022]
Abstract
It has been shown that subunit composition is the main determinant of the synaptic or extrasynaptic localization of GABAA receptors (GABAARs). Synaptic and extrasynaptic GABAARs are involved in phasic and tonic inhibition, respectively. It has been proposed that synaptic GABAARs bind to the postsynaptic gephyrin/collybistin (Geph/CB) lattice, but not the typically extrasynaptic GABAARs. Nevertheless, there are no studies of the direct binding of various types of GABAARs with the submembranous Geph/CB lattice in the absence of other synaptic proteins, some of which are known to interact with GABAARs. We have reconstituted GABAARs of various subunit compositions, together with the Geph/CB scaffold, in HEK293 cells, and have investigated the recruitment of surface GABAARs by submembranous Geph/CB clusters. Results show that the typically synaptic α1β3γ2 GABAARs were trapped by submembranous Geph/CB clusters. The α5β3γ2 GABAARs, which are both synaptic and extrasynaptic, were also trapped by Geph/CB clusters. Extrasynaptic α4β3δ GABAARs consistently showed little or no trapping by the Geph/CB clusters. However, the extrasynaptic α6β3δ, α1β3, α6β3 (and less α4β3) GABAARs were highly trapped by the Geph/CB clusters. AMPA and NMDA glutamate receptors were not trapped. The results suggest: (I) in the absence of other synaptic molecules, the Geph/CB lattice has the capacity to trap not only synaptic but also several typically extrasynaptic GABAARs; (II) the Geph/CB lattice is important but does not play a decisive role in the synaptic localization of GABAARs; and (III) in neurons there must be mechanisms preventing the trapping of several typically extrasynaptic GABAARs by the postsynaptic Geph/CB lattice.
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Affiliation(s)
- Shanu George
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Road, U-3156, Storrs, CT, 06269-3156, USA
| | - Tzu-Ting Chiou
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Road, U-3156, Storrs, CT, 06269-3156, USA
| | - Karthik Kanamalla
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Road, U-3156, Storrs, CT, 06269-3156, USA
| | - Angel L De Blas
- Department of Physiology and Neurobiology, University of Connecticut, 75 North Eagleville Road, U-3156, Storrs, CT, 06269-3156, USA.
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9
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George S, Bear J, Taylor MJ, Kanamalla K, Fekete CD, Chiou TT, Miralles CP, Papadopoulos T, De Blas AL. Collybistin SH3-protein isoforms are expressed in the rat brain promoting gephyrin and GABA-A receptor clustering at GABAergic synapses. J Neurochem 2021; 157:1032-1051. [PMID: 33316079 DOI: 10.1111/jnc.15270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/18/2020] [Accepted: 12/08/2020] [Indexed: 01/21/2023]
Abstract
Collybistin (CB) is a guanine nucleotide exchange factor (GEF) selectively localized at GABAergic and glycinergic postsynapses. Analysis of mRNA shows that several isoforms of collybistin are expressed in the brain. Some of the isoforms have a SH3 domain (CBSH3+) and some have no SH3 domain (CBSH3-). The CBSH3+ mRNAs are predominantly expressed over CBSH3-. However, in an immunoblot study of mouse brain homogenates, only CBSH3+ protein isoforms were detected, proposing that CBSH3- protein might not be expressed in the brain. The expression or lack of expression of CBSH3- protein is an important issue because CBSH3- has a strong effect in promoting the postsynaptic clustering of gephyrin and GABA-A receptors (GABAA Rs). Moreover CBSH3- is constitutively active; therefore lower expression of CBSH3- protein might play a relatively stronger functional role than the more abundant but self-inhibited CBSH3+ isoforms, which need to be activated. We are now showing that: (a) CBSH3- protein is expressed in the brain; (b) parvalbumin positive (PV+) interneurons show higher expression of CBSH3- protein than other neurons; (c) CBSH3- is associated with GABAergic synapses in various regions of the brain and (d) knocking down CBSH3- in hippocampal neurons decreases the synaptic clustering of gephyrin and GABAA Rs. The results show that CBSH3- protein is expressed in the brain and that it plays a significant role in the size regulation of the GABAergic postsynapse.
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Affiliation(s)
- Shanu George
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - John Bear
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Michael J Taylor
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Karthik Kanamalla
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Christopher D Fekete
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Tzu-Ting Chiou
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | - Celia P Miralles
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
| | | | - Angel L De Blas
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, USA
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10
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Nathanson AJ, Zhang Y, Smalley JL, Ollerhead TA, Rodriguez Santos MA, Andrews PM, Wobst HJ, Moore YE, Brandon NJ, Hines RM, Davies PA, Moss SJ. Identification of a Core Amino Acid Motif within the α Subunit of GABA ARs that Promotes Inhibitory Synaptogenesis and Resilience to Seizures. Cell Rep 2020; 28:670-681.e8. [PMID: 31315046 PMCID: PMC8283774 DOI: 10.1016/j.celrep.2019.06.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/08/2019] [Accepted: 06/03/2019] [Indexed: 12/12/2022] Open
Abstract
SUMMARY The fidelity of inhibitory neurotransmission is dependent on the accumulation of γ-aminobutyric acid type A receptors (GABAARs) at the appropriate synaptic sites. Synaptic GABAARs are constructed from α(1–3), β(1–3), and γ2 subunits, and neurons can target these subtypes to specific synapses. Here, we identify a 15-amino acid inhibitory synapse targeting motif (ISTM) within the α2 subunit that promotes the association between GABAARs and the inhibitory scaffold proteins collybistin and gephyrin. Using mice in which the ISTM has been introduced into the α1 subunit (Gabra1–2 mice), we show that the ISTM is critical for axo-axonic synapse formation, the efficacy of GABAergic neurotransmission, and seizure sensitivity. The Gabra1–2 mutation rescues seizure-induced lethality in Gabra2–1 mice, which lack axo-axonic synapses due to the deletion of the ISTM from the α2 subunit. Taken together, our data demonstrate that the ISTM plays a critical role in promoting inhibitory synapse formation, both in the axonic and somatodendritic compartments. In Brief Molecular mechanisms regulating specific synaptic GABAAR accumulation are critical for the fidelity of inhibitory neurotransmission. Nathanson et al. show that strengthening the interaction between α1-GABAARs and collybistin via genetic manipulation results in augmented synaptic targeting of these receptors, enhanced inhibitory neurotransmission, and seizure resilience.
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Affiliation(s)
- Anna J Nathanson
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Yihui Zhang
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Joshua L Smalley
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Thomas A Ollerhead
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | | | - Peter M Andrews
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Heike J Wobst
- AstraZeneca Neuroscience, IMED Biotech Unit, R&D, Boston, MA 02451, USA
| | - Yvonne E Moore
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Nicholas J Brandon
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA 02111, USA; AstraZeneca Neuroscience, IMED Biotech Unit, R&D, Boston, MA 02451, USA
| | - Rochelle M Hines
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
| | - Paul A Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA; AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, MA 02111, USA; Department of Neuroscience, Physiology and Pharmacology, University College, London WC1E 6BT, UK.
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11
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Chiu CQ, Barberis A, Higley MJ. Preserving the balance: diverse forms of long-term GABAergic synaptic plasticity. Nat Rev Neurosci 2019; 20:272-281. [PMID: 30837689 DOI: 10.1038/s41583-019-0141-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cellular mechanisms that regulate the interplay of synaptic excitation and inhibition are thought to be central to the functional stability of healthy neuronal circuits. A growing body of literature demonstrates the capacity for inhibitory GABAergic synapses to exhibit long-term plasticity in response to changes in neuronal activity. Here, we review this expanding field of research, focusing on the diversity of mechanisms that link glutamatergic signalling, postsynaptic action potentials and inhibitory synaptic strength. Several lines of evidence indicate that multiple, parallel forms of plasticity serve to regulate activity at both the input and output domains of individual neurons. Overall, these varied phenomena serve to promote both stability and flexibility over the life of the organism.
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Affiliation(s)
- Chiayu Q Chiu
- Centro Interdisciplinario de Neurociencia de Valparaiso, Universidad de Valparaiso, Valparaiso, Chile
| | | | - Michael J Higley
- Department of Neuroscience, Yale University, New Haven, CT, USA.
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12
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Zhou X, Bessereau JL. Molecular Architecture of Genetically-Tractable GABA Synapses in C. elegans. Front Mol Neurosci 2019; 12:304. [PMID: 31920535 PMCID: PMC6920096 DOI: 10.3389/fnmol.2019.00304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 11/26/2019] [Indexed: 12/18/2022] Open
Abstract
Inhibitory synapses represent a minority of the total chemical synapses in the mammalian brain, yet proper tuning of inhibition is fundamental to shape neuronal network properties. The neurotransmitter γ-aminobutyric acid (GABA) mediates rapid synaptic inhibition by the activation of the type A GABA receptor (GABAAR), a pentameric chloride channel that governs major inhibitory neuronal transduction in the nervous system. Impaired GABA transmission leads to a variety of neuropsychiatric diseases, including schizophrenia, autism, epilepsy or anxiety. From an evolutionary perspective, GABAAR shows remarkable conservations, and are found in all eukaryotic clades and even in bacteria and archaea. Specifically, bona fide GABAARs are found in the nematode Caenorhabditis elegans. Because of the anatomical simplicity of the nervous system and its amenability to genetic manipulations, C. elegans provide a powerful system to investigate the molecular and cellular biology of GABA synapses. In this mini review article, we will introduce the structure of the C. elegans GABAergic system and describe recent advances that have identified novel proteins controlling the localization of GABAARs at synapses. In particular, Ce-Punctin/MADD-4 is an evolutionarily-conserved extracellular matrix protein that behaves as an anterograde synaptic organizer to instruct the excitatory or inhibitory identity of postsynaptic domains.
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Affiliation(s)
- Xin Zhou
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
| | - Jean-Louis Bessereau
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR 5310, INSERM U 1217, Institut NeuroMyoGène, Lyon, France
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13
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Khayenko V, Maric HM. Targeting GABA AR-Associated Proteins: New Modulators, Labels and Concepts. Front Mol Neurosci 2019; 12:162. [PMID: 31293385 PMCID: PMC6606717 DOI: 10.3389/fnmol.2019.00162] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/12/2019] [Indexed: 12/21/2022] Open
Abstract
γ-aminobutyric acid type A receptors (GABAARs) are the major mediators of synaptic inhibition in the brain. Aberrant GABAAR activity or regulation is observed in various neurodevelopmental disorders, neurodegenerative diseases and mental illnesses, including epilepsy, Alzheimer’s and schizophrenia. Benzodiazepines, anesthetics and other pharmaceutics targeting these receptors find broad clinical use, but their inherent lack of receptor subtype specificity causes unavoidable side effects, raising a need for new or adjuvant medications. In this review article, we introduce a new strategy to modulate GABAeric signaling: targeting the intracellular protein interactors of GABAARs. Of special interest are scaffolding, anchoring and supporting proteins that display high GABAAR subtype specificity. Recent efforts to target gephyrin, the major intracellular integrator of GABAergic signaling, confirm that GABAAR-associated proteins can be successfully targeted through diverse molecules, including recombinant proteins, intrabodies, peptide-based probes and small molecules. Small-molecule artemisinins and peptides derived from endogenous interactors, that specifically target the universal receptor binding site of gephyrin, acutely affect synaptic GABAAR numbers and clustering, modifying neuronal transmission. Interference with GABAAR trafficking provides another way to modulate inhibitory signaling. Peptides blocking the binding site of GABAAR to AP2 increase the surface concentration of GABAAR clusters and enhance GABAergic signaling. Engineering of gephyrin binding peptides delivered superior means to interrogate neuronal structure and function. Fluorescent peptides, designed from gephyrin binders, enable live neuronal staining and visualization of gephyrin in the post synaptic sites with submicron resolution. We anticipate that in the future, novel fluorescent probes, with improved size and binding efficiency, may find wide application in super resolution microscopy studies, enlightening the nanoscale architecture of the inhibitory synapse. Broader studies on GABAAR accessory proteins and the identification of the exact molecular binding interfaces and affinities will advance the development of novel GABAAR modulators and following in vivo studies will reveal their clinical potential as adjuvant or stand-alone drugs.
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Affiliation(s)
- Vladimir Khayenko
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
| | - Hans Michael Maric
- Institute of Structural Biology, Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany.,Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
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14
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Que L, Winterer J, Földy C. Deep Survey of GABAergic Interneurons: Emerging Insights From Gene-Isoform Transcriptomics. Front Mol Neurosci 2019; 12:115. [PMID: 31133800 PMCID: PMC6514532 DOI: 10.3389/fnmol.2019.00115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 04/23/2019] [Indexed: 11/13/2022] Open
Abstract
GABAergic interneuron diversity is a key feature in the brain that helps to create different brain activity patterns and behavioral states. Cell type classification schemes—based on anatomical, physiological and molecular features—have provided us with a detailed understanding of the distinct types that constitute this diversity and their contribution to brain function. Over recent years, the utility of single-cell RNAseq has majorly complemented this existing framework, vastly expanding our knowledge base, particularly regarding molecular features. Single-cell gene-expression profiles of tens of thousands of GABAergic cells from many different types are now available. The analysis of these data has shed new lights onto previous classification principles and illuminates a path towards a deeper understanding of molecular hallmarks behind interneuron diversity. A large part of such molecular features is synapse-related. These include ion channels and receptors, as well as key synaptic organizers and trans-synaptic signaling molecules. Increasing evidence suggests that transcriptional and post-transcriptional modifications further diversify these molecules and generate cell type-specific features. Thus, unraveling the cell type-specific nature of gene-isoform expression will be a key in cell type classification. This review article discusses progress in the transcriptomic survey of interneurons and insights that have begun to manifest from isoform-level analyses.
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Affiliation(s)
- Lin Que
- Laboratory of Neural Connectivity, Faculties of Medicine and Natural Sciences, Brain Research Institute, University of Zurich, Zurich, Switzerland
| | - Jochen Winterer
- Laboratory of Neural Connectivity, Faculties of Medicine and Natural Sciences, Brain Research Institute, University of Zurich, Zurich, Switzerland
| | - Csaba Földy
- Laboratory of Neural Connectivity, Faculties of Medicine and Natural Sciences, Brain Research Institute, University of Zurich, Zurich, Switzerland
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15
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Specht CG. Fractional occupancy of synaptic binding sites and the molecular plasticity of inhibitory synapses. Neuropharmacology 2019; 169:107493. [PMID: 30648560 DOI: 10.1016/j.neuropharm.2019.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 12/01/2018] [Accepted: 01/09/2019] [Indexed: 01/20/2023]
Abstract
The postsynaptic density (PSD) at inhibitory synapses is a complex molecular assembly that serves as a platform for the interaction of neurotransmitter receptors, scaffold and adapter proteins, cytoskeletal elements and signalling molecules. The stability of the PSD depends on a multiplicity of interactions linking individual components. At the same time the PSD retains a substantial degree of flexibility. The continuous exchange of synaptic molecules and the preferential addition or removal of certain components induce plastic changes in the synaptic structure. This property necessarily implies that interactors are in dynamic equilibrium and that not all synaptic binding sites are occupied simultaneously. This review discusses the molecular plasticity of inhibitory synapses in terms of the connectivity of their components. Whereas stable protein complexes are marked by stoichiometric relationships between subunits, the majority of synaptic interactions have fractional occupancy, which is here defined as the non-saturation of synaptic binding sites. Fractional occupancy can have several causes: reduced kinetic or thermodynamic stability of the interactions, an imbalance in the concentrations or limited spatio-temporal overlap of interacting proteins, negative cooperativity or mutually exclusive binding. The role of fractional occupancy in the regulation of synaptic structure and function is explored based on recent data about the connectivity of inhibitory receptors and scaffold proteins. I propose that the absolute quantification of interactors and their stoichiometry at identified synapses can provide new mechanistic insights into the dynamic properties of inhibitory PSDs at the molecular level. This article is part of the special issue entitled 'Mobility and trafficking of neuronal membrane proteins'.
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Affiliation(s)
- Christian G Specht
- École Normale Supérieure, PSL Research University, CNRS, Inserm, Institute of Biology (IBENS), Paris, 75005, France.
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16
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Groeneweg FL, Trattnig C, Kuhse J, Nawrotzki RA, Kirsch J. Gephyrin: a key regulatory protein of inhibitory synapses and beyond. Histochem Cell Biol 2018; 150:489-508. [DOI: 10.1007/s00418-018-1725-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2018] [Indexed: 12/26/2022]
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17
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Hines RM, Maric HM, Hines DJ, Modgil A, Panzanelli P, Nakamura Y, Nathanson AJ, Cross A, Deeb T, Brandon NJ, Davies P, Fritschy JM, Schindelin H, Moss SJ. Developmental seizures and mortality result from reducing GABA A receptor α2-subunit interaction with collybistin. Nat Commun 2018; 9:3130. [PMID: 30087324 PMCID: PMC6081406 DOI: 10.1038/s41467-018-05481-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 07/05/2018] [Indexed: 01/08/2023] Open
Abstract
Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2-1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development.
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Affiliation(s)
- Rochelle M Hines
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA.
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, 89154, Ne, USA.
| | - Hans Michael Maric
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, D-97080, Germany
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, D-97080, Germany
| | - Dustin J Hines
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
- Department of Psychology, University of Nevada Las Vegas, Las Vegas, 89154, Ne, USA
| | - Amit Modgil
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini, University of Turin, Turin, 10126, Italy
| | - Yasuko Nakamura
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Anna J Nathanson
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Alan Cross
- AstraZeneca Neuroscience iMED, Biotech Unit, Boston, 02451, MA, USA
| | - Tarek Deeb
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA
| | - Nicholas J Brandon
- AstraZeneca Neuroscience iMED, Biotech Unit, Boston, 02451, MA, USA
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA
| | - Paul Davies
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, 8057, Switzerland
- Center for Neuroscience Zurich, University of Zurich and ETH Zurich, Zurich, 8057, Switzerland
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, D-97080, Germany
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, 02111, MA, USA.
- AstraZeneca Tufts Laboratory for Basic and Translational Neuroscience, Boston, 02111, MA, USA.
- Department of Neuroscience, Physiology and Pharmacology, University College, London, WC1E 6BT, UK.
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18
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Virtanen MA, Lacoh CM, Fiumelli H, Kosel M, Tyagarajan S, de Roo M, Vutskits L. Development of inhibitory synaptic inputs on layer 2/3 pyramidal neurons in the rat medial prefrontal cortex. Brain Struct Funct 2018; 223:1999-2012. [PMID: 29322238 DOI: 10.1007/s00429-017-1602-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 12/28/2017] [Indexed: 02/03/2023]
Abstract
Inhibitory control of pyramidal neurons plays a major role in governing the excitability in the brain. While spatial mapping of inhibitory inputs onto pyramidal neurons would provide important structural data on neuronal signaling, studying their distribution at the single cell level is difficult due to the lack of easily identifiable anatomical proxies. Here, we describe an approach where in utero electroporation of a plasmid encoding for fluorescently tagged gephyrin into the precursors of pyramidal cells along with ionotophoretic injection of Lucifer Yellow can reliably and specifically detect GABAergic synapses on the dendritic arbour of single pyramidal neurons. Using this technique and focusing on the basal dendritic arbour of layer 2/3 pyramidal cells of the medial prefrontal cortex, we demonstrate an intense development of GABAergic inputs onto these cells between postnatal days 10 and 20. While the spatial distribution of gephyrin clusters was not affected by the distance from the cell body at postnatal day 10, we found that distal dendritic segments appeared to have a higher gephyrin density at later developmental stages. We also show a transient increase around postnatal day 20 in the percentage of spines that are carrying a gephyrin cluster, indicative of innervation by a GABAergic terminal. Since the precise spatial arrangement of synaptic inputs is an important determinant of neuronal responses, we believe that the method described in this work may allow a better understanding of how inhibition settles together with excitation, and serve as basics for further modelling studies focusing on the geometry of dendritic inhibition during development.
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Affiliation(s)
- Mari A Virtanen
- Department of Basic Neuroscience, University of Geneva Medical School, Geneva, Switzerland.,Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Claudia Marvine Lacoh
- Department of Basic Neuroscience, University of Geneva Medical School, Geneva, Switzerland
| | - Hubert Fiumelli
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Markus Kosel
- Department of Psychiatry, University of Geneva Medical School, Geneva, Switzerland
| | - Shiva Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Mathias de Roo
- Department of Basic Neuroscience, University of Geneva Medical School, Geneva, Switzerland.,Department of Anesthesiology, Pharmacology and Intensive Care, University Hospitals of Geneva, 4, rue Gabrielle-Perret-Gentil, 1211, Geneva 4, Switzerland
| | - Laszlo Vutskits
- Department of Basic Neuroscience, University of Geneva Medical School, Geneva, Switzerland. .,Department of Anesthesiology, Pharmacology and Intensive Care, University Hospitals of Geneva, 4, rue Gabrielle-Perret-Gentil, 1211, Geneva 4, Switzerland.
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19
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Correlating Fluorescence and High-Resolution Scanning Electron Microscopy (HRSEM) for the study of GABA A receptor clustering induced by inhibitory synaptic plasticity. Sci Rep 2017; 7:13768. [PMID: 29061992 PMCID: PMC5653763 DOI: 10.1038/s41598-017-14210-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/05/2017] [Indexed: 02/03/2023] Open
Abstract
Both excitatory and inhibitory synaptic contacts display activity dependent dynamic changes in their efficacy that are globally termed synaptic plasticity. Although the molecular mechanisms underlying glutamatergic synaptic plasticity have been extensively investigated and described, those responsible for inhibitory synaptic plasticity are only beginning to be unveiled. In this framework, the ultrastructural changes of the inhibitory synapses during plasticity have been poorly investigated. Here we combined confocal fluorescence microscopy (CFM) with high resolution scanning electron microscopy (HRSEM) to characterize the fine structural rearrangements of post-synaptic GABAA Receptors (GABAARs) at the nanometric scale during the induction of inhibitory long-term potentiation (iLTP). Additional electron tomography (ET) experiments on immunolabelled hippocampal neurons allowed the visualization of synaptic contacts and confirmed the reorganization of post-synaptic GABAAR clusters in response to chemical iLTP inducing protocol. Altogether, these approaches revealed that, following the induction of inhibitory synaptic potentiation, GABAAR clusters increase in size and number at the post-synaptic membrane with no other major structural changes of the pre- and post-synaptic elements.
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20
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Abstract
In this issue of Neuron, Fossati et al. (2016) report that through its domain structure, SRGAP2A, a Rho-GTPase-activating protein, can co-regulate excitatory and inhibitory synapse development, offering a putative evolutionary genetic mechanism for preserving excitatory/inhibitory balance during speciation.
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Affiliation(s)
- Jaichandar Subramanian
- Picower Institute for Learning and Memory, Departments of Biology and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Elly Nedivi
- Picower Institute for Learning and Memory, Departments of Biology and Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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21
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Martin-Vilchez S, Whitmore L, Asmussen H, Zareno J, Horwitz R, Newell-Litwa K. RhoGTPase Regulators Orchestrate Distinct Stages of Synaptic Development. PLoS One 2017; 12:e0170464. [PMID: 28114311 PMCID: PMC5256999 DOI: 10.1371/journal.pone.0170464] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 01/05/2017] [Indexed: 11/19/2022] Open
Abstract
Small RhoGTPases regulate changes in post-synaptic spine morphology and density that support learning and memory. They are also major targets of synaptic disorders, including Autism. Here we sought to determine whether upstream RhoGTPase regulators, including GEFs, GAPs, and GDIs, sculpt specific stages of synaptic development. The majority of examined molecules uniquely regulate either early spine precursor formation or later maturation. Specifically, an activator of actin polymerization, the Rac1 GEF β-PIX, drives spine precursor formation, whereas both FRABIN, a Cdc42 GEF, and OLIGOPHRENIN-1, a RhoA GAP, regulate spine precursor elongation. However, in later development, a novel Rac1 GAP, ARHGAP23, and RhoGDIs inactivate actomyosin dynamics to stabilize mature synapses. Our observations demonstrate that specific combinations of RhoGTPase regulatory proteins temporally balance RhoGTPase activity during post-synaptic spine development.
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Affiliation(s)
- Samuel Martin-Vilchez
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Leanna Whitmore
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Hannelore Asmussen
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Jessica Zareno
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Rick Horwitz
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
| | - Karen Newell-Litwa
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, United States of America
- Department of Anatomy and Cell Biology, Brody School of Medicine, East Carolina University, Greenville, NC, United States of America
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22
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Papadopoulos T, Rhee HJ, Subramanian D, Paraskevopoulou F, Mueller R, Schultz C, Brose N, Rhee JS, Betz H. Endosomal Phosphatidylinositol 3-Phosphate Promotes Gephyrin Clustering and GABAergic Neurotransmission at Inhibitory Postsynapses. J Biol Chem 2016; 292:1160-1177. [PMID: 27941024 DOI: 10.1074/jbc.m116.771592] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Indexed: 11/06/2022] Open
Abstract
The formation of neuronal synapses and the dynamic regulation of their efficacy depend on the proper assembly of the postsynaptic neurotransmitter receptor apparatus. Receptor recruitment to inhibitory GABAergic postsynapses requires the scaffold protein gephyrin and the guanine nucleotide exchange factor collybistin (Cb). In vitro, the pleckstrin homology domain of Cb binds phosphoinositides, specifically phosphatidylinositol 3-phosphate (PI3P). However, whether PI3P is required for inhibitory postsynapse formation is currently unknown. Here, we investigated the role of PI3P at developing GABAergic postsynapses by using a membrane-permeant PI3P derivative, time-lapse confocal imaging, electrophysiology, as well as knockdown and overexpression of PI3P-metabolizing enzymes. Our results provide the first in cellula evidence that PI3P located at early/sorting endosomes regulates the postsynaptic clustering of gephyrin and GABAA receptors and the strength of inhibitory, but not excitatory, postsynapses in cultured hippocampal neurons. In human embryonic kidney 293 cells, stimulation of gephyrin cluster formation by PI3P depends on Cb. We therefore conclude that the endosomal pool of PI3P, generated by the class III phosphatidylinositol 3-kinase, is important for the Cb-mediated recruitment of gephyrin and GABAA receptors to developing inhibitory postsynapses and thus the formation of postsynaptic membrane specializations.
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Affiliation(s)
- Theofilos Papadopoulos
- From the Department of Molecular Biology, Center of Biochemistry and Molecular Cell Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany,
| | - Hong Jun Rhee
- the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Devaraj Subramanian
- the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Foteini Paraskevopoulou
- From the Department of Molecular Biology, Center of Biochemistry and Molecular Cell Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Rainer Mueller
- the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Carsten Schultz
- the European Molecular Biology Laboratory (EMBL), Cell Biology and Biophysics Unit, Meyerhofstrasse 1, 69117 Heidelberg, Germany.,the Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239-3098
| | - Nils Brose
- the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Jeong-Seop Rhee
- the Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Heinrich Betz
- the Department of Neurochemistry, Max Planck Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany, and.,the Max Planck Institute of Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
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23
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Fekete CD, Goz RU, Dinallo S, Miralles CP, Chiou TT, Bear J, Fiondella CG, LoTurco JJ, De Blas AL. In vivo transgenic expression of collybistin in neurons of the rat cerebral cortex. J Comp Neurol 2016; 525:1291-1311. [PMID: 27804142 DOI: 10.1002/cne.24137] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/18/2016] [Accepted: 10/19/2016] [Indexed: 01/12/2023]
Abstract
Collybistin (CB) is a guanine nucleotide exchange factor selectively localized to γ-aminobutyric acid (GABA)ergic and glycinergic postsynapses. Active CB interacts with gephyrin, inducing the submembranous clustering and the postsynaptic accumulation of gephyrin, which is a scaffold protein that recruits GABAA receptors (GABAA Rs) at the postsynapse. CB is expressed with or without a src homology 3 (SH3) domain. We have previously reported the effects on GABAergic synapses of the acute overexpression of CBSH3- or CBSH3+ in cultured hippocampal (HP) neurons. In the present communication, we are studying the effects on GABAergic synapses after chronic in vivo transgenic expression of CB2SH3- or CB2SH3+ in neurons of the adult rat cerebral cortex. The embryonic precursors of these cortical neurons were in utero electroporated with CBSH3- or CBSH3+ DNAs, migrated to the appropriate cortical layer, and became integrated in cortical circuits. The results show that: 1) the strength of inhibitory synapses in vivo can be enhanced by increasing the expression of CB in neurons; and 2) there are significant differences in the results between in vivo and in culture studies. J. Comp. Neurol. 525:1291-1311, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Christopher D Fekete
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Roman U Goz
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Sean Dinallo
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Celia P Miralles
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Tzu-Ting Chiou
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - John Bear
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Christopher G Fiondella
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Joseph J LoTurco
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
| | - Angel L De Blas
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269
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24
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Ghosh H, Auguadri L, Battaglia S, Simone Thirouin Z, Zemoura K, Messner S, Acuña MA, Wildner H, Yévenes GE, Dieter A, Kawasaki H, O Hottiger M, Zeilhofer HU, Fritschy JM, Tyagarajan SK. Several posttranslational modifications act in concert to regulate gephyrin scaffolding and GABAergic transmission. Nat Commun 2016; 7:13365. [PMID: 27819299 PMCID: PMC5103071 DOI: 10.1038/ncomms13365] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 09/26/2016] [Indexed: 11/18/2022] Open
Abstract
GABAA receptors (GABAARs) mediate the majority of fast inhibitory neurotransmission in the brain via synergistic association with the postsynaptic scaffolding protein gephyrin and its interaction partners. However, unlike their counterparts at glutamatergic synapses, gephyrin and its binding partners lack canonical protein interaction motifs; hence, the molecular basis for gephyrin scaffolding has remained unclear. In this study, we identify and characterize two new posttranslational modifications of gephyrin, SUMOylation and acetylation. We demonstrate that crosstalk between SUMOylation, acetylation and phosphorylation pathways regulates gephyrin scaffolding. Pharmacological intervention of SUMO pathway or transgenic expression of SUMOylation-deficient gephyrin variants rescued gephyrin clustering in CA1 or neocortical neurons of Gabra2-null mice, which otherwise lack gephyrin clusters, indicating that gephyrin SUMO modification is an essential determinant for scaffolding at GABAergic synapses. Together, our results demonstrate that concerted modifications on a protein scaffold by evolutionarily conserved yet functionally diverse signalling pathways facilitate GABAergic transmission. Gephyrin is a cytoplasmic scaffolding protein that selectively forms postsynaptic scaffolds at GABAergic and glycinergic synapses. Here the authors characterize regulatory mechanisms determining gephyrin scaffolding and GABAA receptor synaptic transmission that involve acetylation, SUMOylation and phosphorylation.
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Affiliation(s)
- Himanish Ghosh
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Luca Auguadri
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland
| | - Sereina Battaglia
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland
| | - Zahra Simone Thirouin
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Khaled Zemoura
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Simon Messner
- Department of Molecular Mechanisms of Disease, University of Zurich, CH 8057 Zurich, Switzerland
| | - Mario A Acuña
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Hendrik Wildner
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Gonzalo E Yévenes
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland
| | - Andrea Dieter
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland
| | - Hiroshi Kawasaki
- Department of Molecular and Systems Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Michael O Hottiger
- Department of Molecular Mechanisms of Disease, University of Zurich, CH 8057 Zurich, Switzerland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland.,Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology, CH 8093 Zurich, Switzerland
| | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
| | - Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland.,Center for Neuroscience Zurich, CH 8057 Zurich, Switzerland
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25
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Regulation of GABAergic synapse development by postsynaptic membrane proteins. Brain Res Bull 2016; 129:30-42. [PMID: 27453545 DOI: 10.1016/j.brainresbull.2016.07.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 07/06/2016] [Indexed: 02/07/2023]
Abstract
In the adult mammalian brain, GABAergic neurotransmission provides the majority of synaptic inhibition that balances glutamatergic excitatory drive and thereby controls neuronal output. It is generally accepted that synaptogenesis is initiated through highly specific protein-protein interactions mediated by membrane proteins expressed in developing presynaptic terminals and postsynaptic membranes. Accumulating studies have uncovered a number of membrane proteins that regulate different aspects of GABAergic synapse development. In this review, we summarize recent advances in understanding of GABAergic synapse development with a focus on postsynaptic membrane molecules, including receptors, synaptogenic cell adhesion molecules and immunoglobulin superfamily proteins.
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26
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Lenz M, Galanis C, Müller-Dahlhaus F, Opitz A, Wierenga CJ, Szabó G, Ziemann U, Deller T, Funke K, Vlachos A. Repetitive magnetic stimulation induces plasticity of inhibitory synapses. Nat Commun 2016; 7:10020. [PMID: 26743822 PMCID: PMC4729863 DOI: 10.1038/ncomms10020] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 10/26/2015] [Indexed: 12/21/2022] Open
Abstract
Repetitive transcranial magnetic stimulation (rTMS) is used as a therapeutic tool in neurology and psychiatry. While repetitive magnetic stimulation (rMS) has been shown to induce plasticity of excitatory synapses, it is unclear whether rMS can also modify structural and functional properties of inhibitory inputs. Here we employed 10-Hz rMS of entorhinohippocampal slice cultures to study plasticity of inhibitory neurotransmission on CA1 pyramidal neurons. Our experiments reveal a rMS-induced reduction in GABAergic synaptic strength (2-4 h after stimulation), which is Ca(2+)-dependent and accompanied by the remodelling of postsynaptic gephyrin scaffolds. Furthermore, we present evidence that 10-Hz rMS predominantly acts on dendritic, but not somatic inhibition. Consistent with this finding, a reduction in clustered gephyrin is detected in CA1 stratum radiatum of rTMS-treated anaesthetized mice. These results disclose that rTMS induces coordinated Ca(2+)-dependent structural and functional changes of specific inhibitory postsynapses on principal neurons.
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Affiliation(s)
- Maximilian Lenz
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt/Main 60590, Germany
| | - Christos Galanis
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt/Main 60590, Germany
| | - Florian Müller-Dahlhaus
- Department of Neurology and Stroke and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, Tübingen 72076, Germany
| | - Alexander Opitz
- Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute for Psychiatric Research, Orangeburg, New York 10962, USA.,Center for the Developing Brain, Child Mind Institute, New York, New York 10022, USA
| | - Corette J Wierenga
- Division of Cell Biology, Faculty of Science, Utrecht University, Utrecht 3584 CH, The Netherlands
| | - Gábor Szabó
- Laboratory of Molecular Biology and Genetics, Institute of Experimental Medicine, Budapest H1083, Hungary
| | - Ulf Ziemann
- Department of Neurology and Stroke and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University, Tübingen 72076, Germany
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt/Main 60590, Germany
| | - Klaus Funke
- Department of Neurophysiology, Medical Faculty, Ruhr-University, Bochum 44780, Germany
| | - Andreas Vlachos
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe-University, Frankfurt/Main 60590, Germany
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27
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Ludolphs M, Schneeberger D, Soykan T, Schäfer J, Papadopoulos T, Brose N, Schindelin H, Steinem C. Specificity of Collybistin-Phosphoinositide Interactions: IMPACT OF THE INDIVIDUAL PROTEIN DOMAINS. J Biol Chem 2015; 291:244-54. [PMID: 26546675 DOI: 10.1074/jbc.m115.673400] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Indexed: 01/01/2023] Open
Abstract
The regulatory protein collybistin (CB) recruits the receptor-scaffolding protein gephyrin to mammalian inhibitory glycinergic and GABAergic postsynaptic membranes in nerve cells. CB is tethered to the membrane via phosphoinositides. We developed an in vitro assay based on solid-supported 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes doped with different phosphoinositides on silicon/silicon dioxide substrates to quantify the binding of various CB2 constructs using reflectometric interference spectroscopy. Based on adsorption isotherms, we obtained dissociation constants and binding capacities of the membranes. Our results show that full-length CB2 harboring the N-terminal Src homology 3 (SH3) domain (CB2SH3+) adopts a closed and autoinhibited conformation that largely prevents membrane binding. This autoinhibition is relieved upon introduction of the W24A/E262A mutation, which conformationally "opens" CB2SH3+ and allows the pleckstrin homology domain to properly bind lipids depending on the phosphoinositide species with a preference for phosphatidylinositol 3-monophosphate and phosphatidylinositol 4-monophosphate. This type of membrane tethering under the control of the release of the SH3 domain of CB is essential for regulating gephyrin clustering.
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Affiliation(s)
- Michaela Ludolphs
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Daniela Schneeberger
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Tolga Soykan
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Jonas Schäfer
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany
| | - Theofilos Papadopoulos
- Universitätsmedizin Göttingen, Department of Molecular Biology, Humboldtallee 23, 37073 Göttingen, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany, and
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany
| | - Claudia Steinem
- From the Institute of Organic and Biomolecular Chemistry, University of Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany,
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28
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Collybistin binds and inhibits mTORC1 signaling: a potential novel mechanism contributing to intellectual disability and autism. Eur J Hum Genet 2015; 24:59-65. [PMID: 25898924 DOI: 10.1038/ejhg.2015.69] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 01/27/2015] [Accepted: 03/10/2015] [Indexed: 12/19/2022] Open
Abstract
Protein synthesis regulation via mammalian target of rapamycin complex 1 (mTORC1) signaling pathway has key roles in neural development and function, and its dysregulation is involved in neurodevelopmental disorders associated with autism and intellectual disability. mTOR regulates assembly of the translation initiation machinery by interacting with the eukaryotic initiation factor eIF3 complex and by controlling phosphorylation of key translational regulators. Collybistin (CB), a neuron-specific Rho-GEF responsible for X-linked intellectual disability with epilepsy, also interacts with eIF3, and its binding partner gephyrin associates with mTOR. Therefore, we hypothesized that CB also binds mTOR and affects mTORC1 signaling activity in neuronal cells. Here, by using induced pluripotent stem cell-derived neural progenitor cells from a male patient with a deletion of entire CB gene and from control individuals, as well as a heterologous expression system, we describe that CB physically interacts with mTOR and inhibits mTORC1 signaling pathway and protein synthesis. These findings suggest that disinhibited mTORC1 signaling may also contribute to the pathological process in patients with loss-of-function variants in CB.
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29
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Choii G, Ko J. Gephyrin: a central GABAergic synapse organizer. Exp Mol Med 2015; 47:e158. [PMID: 25882190 DOI: 10.1038/emm.2015.5] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 12/18/2014] [Indexed: 01/22/2023] Open
Abstract
Gephyrin is a central element that anchors, clusters and stabilizes glycine and γ-aminobutyric acid type A receptors at inhibitory synapses of the mammalian brain. It self-assembles into a hexagonal lattice and interacts with various inhibitory synaptic proteins. Intriguingly, the clustering of gephyrin, which is regulated by multiple posttranslational modifications, is critical for inhibitory synapse formation and function. In this review, we summarize the basic properties of gephyrin and describe recent findings regarding its roles in inhibitory synapse formation, function and plasticity. We will also discuss the implications for the pathophysiology of brain disorders and raise the remaining open questions in this field.
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Affiliation(s)
- Gayoung Choii
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Jaewon Ko
- 1] Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea [2] Department of Psychiatry, Yonsei University College of Medicine, Seoul, Korea
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30
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Papadopoulos T, Schemm R, Grubmüller H, Brose N. Lipid binding defects and perturbed synaptogenic activity of a Collybistin R290H mutant that causes epilepsy and intellectual disability. J Biol Chem 2015; 290:8256-70. [PMID: 25678704 DOI: 10.1074/jbc.m114.633024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Signaling at nerve cell synapses is a key determinant of proper brain function, and synaptic defects--or synaptopathies--are at the basis of many neurological and psychiatric disorders. In key areas of the mammalian brain, such as the hippocampus or the basolateral amygdala, the clustering of the scaffolding protein Gephyrin and of γ-aminobutyric acid type A receptors at inhibitory neuronal synapses is critically dependent upon the brain-specific guanine nucleotide exchange factor Collybistin (Cb). Accordingly, it was discovered recently that an R290H missense mutation in the diffuse B-cell lymphoma homology domain of Cb, which carries the guanine nucleotide exchange factor activity, leads to epilepsy and intellectual disability in human patients. In the present study, we determined the mechanism by which the Cb(R290H) mutation perturbs inhibitory synapse formation and causes brain dysfunction. Based on a combination of biochemical, cell biological, and molecular dynamics simulation approaches, we demonstrate that the R290H mutation alters the strength of intramolecular interactions between the diffuse B-cell lymphoma homology domain and the pleckstrin homology domain of Cb. This defect reduces the phosphatidylinositol 3-phosphate binding affinity of Cb, which limits its normal synaptogenic activity. Our data indicate that impairment of the membrane lipid binding activity of Cb and a consequent defect in inhibitory synapse maturation represent a likely molecular pathomechanism of epilepsy and mental retardation in humans.
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Affiliation(s)
- Theofilos Papadopoulos
- From the Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany, and
| | - Rudolf Schemm
- the Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Helmut Grubmüller
- the Department of Theoretical and Computational Biophysics, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Nils Brose
- From the Department of Molecular Neurobiology, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany, and
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31
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Luscher B, Fuchs T. GABAergic control of depression-related brain states. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 73:97-144. [PMID: 25637439 DOI: 10.1016/bs.apha.2014.11.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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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32
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Activity-dependent inhibitory synapse remodeling through gephyrin phosphorylation. Proc Natl Acad Sci U S A 2014; 112:E65-72. [PMID: 25535349 DOI: 10.1073/pnas.1411170112] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Maintaining a proper balance between excitation and inhibition is essential for the functioning of neuronal networks. However, little is known about the mechanisms through which excitatory activity can affect inhibitory synapse plasticity. Here we used tagged gephyrin, one of the main scaffolding proteins of the postsynaptic density at GABAergic synapses, to monitor the activity-dependent adaptation of perisomatic inhibitory synapses over prolonged periods of time in hippocampal slice cultures. We find that learning-related activity patterns known to induce N-methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation and transient optogenetic activation of single neurons induce within hours a robust increase in the formation and size of gephyrin-tagged clusters at inhibitory synapses identified by correlated confocal electron microscopy. This inhibitory morphological plasticity was associated with an increase in spontaneous inhibitory activity but did not require activation of GABAA receptors. Importantly, this activity-dependent inhibitory plasticity was prevented by pharmacological blockade of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), it was associated with an increased phosphorylation of gephyrin on a site targeted by CaMKII, and could be prevented or mimicked by gephyrin phospho-mutants for this site. These results reveal a homeostatic mechanism through which activity regulates the dynamics and function of perisomatic inhibitory synapses, and they identify a CaMKII-dependent phosphorylation site on gephyrin as critically important for this process.
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33
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Flores CE, Méndez P. Shaping inhibition: activity dependent structural plasticity of GABAergic synapses. Front Cell Neurosci 2014; 8:327. [PMID: 25386117 PMCID: PMC4209871 DOI: 10.3389/fncel.2014.00327] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 09/28/2014] [Indexed: 11/22/2022] Open
Abstract
Inhibitory transmission through the neurotransmitter γ-aminobutyric acid (GABA) shapes network activity in the mammalian cerebral cortex by filtering synaptic incoming information and dictating the activity of principal cells. The incredibly diverse population of cortical neurons that use GABA as neurotransmitter shows an equally diverse range of mechanisms that regulate changes in the strength of GABAergic synaptic transmission and allow them to dynamically follow and command the activity of neuronal ensembles. Similarly to glutamatergic synaptic transmission, activity-dependent functional changes in inhibitory neurotransmission are accompanied by alterations in GABAergic synapse structure that range from morphological reorganization of postsynaptic density to de novo formation and elimination of inhibitory contacts. Here we review several aspects of structural plasticity of inhibitory synapses, including its induction by different forms of neuronal activity, behavioral and sensory experience and the molecular mechanisms and signaling pathways involved. We discuss the functional consequences of GABAergic synapse structural plasticity for information processing and memory formation in view of the heterogenous nature of the structural plasticity phenomena affecting inhibitory synapses impinging on somatic and dendritic compartments of cortical and hippocampal neurons.
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Affiliation(s)
- Carmen E Flores
- Department of Basic Neuroscience, Geneva Medical Center, University of Geneva Geneva, Switzerland
| | - Pablo Méndez
- Department of Basic Neuroscience, Geneva Medical Center, University of Geneva Geneva, Switzerland
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34
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Soykan T, Schneeberger D, Tria G, Buechner C, Bader N, Svergun D, Tessmer I, Poulopoulos A, Papadopoulos T, Varoqueaux F, Schindelin H, Brose N. A conformational switch in collybistin determines the differentiation of inhibitory postsynapses. EMBO J 2014; 33:2113-33. [PMID: 25082542 DOI: 10.15252/embj.201488143] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The formation of neuronal synapses and the dynamic regulation of their efficacy depend on the assembly of the postsynaptic neurotransmitter receptor apparatus. Receptor recruitment to inhibitory GABAergic and glycinergic synapses is controlled by the scaffold protein gephyrin and the adaptor protein collybistin. We derived new insights into the structure of collybistin and used these to design biochemical, cell biological, and genetic analyses of collybistin function. Our data define a collybistin-based protein interaction network that controls the gephyrin content of inhibitory postsynapses. Within this network, collybistin can adopt open/active and closed/inactive conformations to act as a switchable adaptor that links gephyrin to plasma membrane phosphoinositides. This function of collybistin is regulated by binding of the adhesion protein neuroligin-2, which stabilizes the open/active conformation of collybistin at the postsynaptic plasma membrane by competing with an intramolecular interaction in collybistin that favors the closed/inactive conformation. By linking trans-synaptic neuroligin-dependent adhesion and phosphoinositide signaling with gephyrin recruitment, the collybistin-based regulatory switch mechanism represents an integrating regulatory node in the formation and function of inhibitory postsynapses.
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Affiliation(s)
- Tolga Soykan
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Daniela Schneeberger
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Giancarlo Tria
- European Molecular Biology Laboratory, Hamburg Outstation, Hamburg, Germany Centre for Bioinformatics, University of Hamburg, Hamburg, Germany
| | - Claudia Buechner
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Nicole Bader
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Dmitri Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Hamburg, Germany
| | - Ingrid Tessmer
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Alexandros Poulopoulos
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Theofilos Papadopoulos
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Frédérique Varoqueaux
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
| | - Hermann Schindelin
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Göttingen, Germany
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35
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Pallotto M, Deprez F. Regulation of adult neurogenesis by GABAergic transmission: signaling beyond GABAA-receptors. Front Cell Neurosci 2014; 8:166. [PMID: 24999317 PMCID: PMC4064292 DOI: 10.3389/fncel.2014.00166] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/02/2014] [Indexed: 01/09/2023] Open
Abstract
In the adult mammalian brain, neurogenesis occurs in the olfactory bulb (OB) and in the dentate gyrus (DG) of the hippocampus. Several studies have shown that multiple stages of neurogenesis are regulated by GABAergic transmission with precise spatio-temporal selectivity, and involving mechanisms common to both systems or specific only to one. In the subgranular zone (SGZ) of the DG, GABA neurotransmitter, released by a specific population of interneurons, regulates stem cell quiescence and neuronal cell fate decisions. Similarly, in the subventricular zone (SVZ), OB neuroblast production is modulated by ambient GABA. Ambient GABA, acting on extrasynaptic GABAA receptors (GABAAR), is also crucial for proper adult-born granule cell (GC) maturation and synaptic integration in the OB as well as in the DG. Throughout adult-born neuron development, various GABA receptors and receptor subunits play specific roles. Previous work has demonstrated that adult-born GCs in both the OB and the DG show a time window of increased plasticity in which adult-born cells are more prone to modification by external stimuli. One mechanism that controls this "critical period" is GABAergic modulation. Indeed, depleting the main phasic GABAergic inputs in adult-born neurons results in dramatic effects, such as reduction of spine density and dendritic branching in adult-born OB GCs. In this review, we systematically compare the role of GABAergic transmission in the regulation of adult neurogenesis between the OB and the hippocampus, focusing on the role of GABA in modulating plasticity and critical periods of adult-born neuron development. Finally, we discuss signaling pathways that might mediate some of the deficits observed upon targeted deletion of postsynaptic GABAARs in adult-born neurons.
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Affiliation(s)
- Marta Pallotto
- Circuit Dynamics and Connectivity Unit, National Institute Neurological Disorders and Stroke, National Institute of Health Bethesda, MD, USA
| | - Francine Deprez
- Neuroscience Center Zurich, Institute of Pharmacology and Toxicology, University of Zurich Zurich, Switzerland
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36
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Abstract
The neurotransmitters GABA and glycine mediate fast synaptic inhibition by activating ligand-gated chloride channels--namely, type A GABA (GABA(A)) and glycine receptors. Both types of receptors are anchored postsynaptically by gephyrin, which self-assembles into a scaffold and interacts with the cytoskeleton. Current research indicates that postsynaptic gephyrin clusters are dynamic assemblies that are held together and regulated by multiple protein-protein interactions. Moreover, post-translational modifications of gephyrin regulate the formation and plasticity of GABAergic synapses by altering the clustering properties of postsynaptic scaffolds and thereby the availability and function of receptors and other signalling molecules. Here, we discuss the formation and regulation of the gephyrin scaffold, its role in GABAergic and glycinergic synaptic function and the implications for the pathophysiology of brain disorders caused by abnormal inhibitory neurotransmission.
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37
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Hanin G, Shenhar-Tsarfaty S, Yayon N, Yau YH, Hoe YY, Bennett ER, Sklan EH, Rao DC, Rankinen T, Bouchard C, Geifman-Shochat S, Shifman S, Greenberg DS, Soreq H. Competing targets of microRNA-608 affect anxiety and hypertension. Hum Mol Genet 2014; 23:4569-80. [PMID: 24722204 PMCID: PMC4119407 DOI: 10.1093/hmg/ddu170] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs) can repress multiple targets, but how a single de-balanced interaction affects others remained unclear. We found that changing a single miRNA-target interaction can simultaneously affect multiple other miRNA-target interactions and modify physiological phenotype. We show that miR-608 targets acetylcholinesterase (AChE) and demonstrate weakened miR-608 interaction with the rs17228616 AChE allele having a single-nucleotide polymorphism (SNP) in the 3'-untranslated region (3'UTR). In cultured cells, this weakened interaction potentiated miR-608-mediated suppression of other targets, including CDC42 and interleukin-6 (IL6). Postmortem human cortices homozygote for the minor rs17228616 allele showed AChE elevation and CDC42/IL6 decreases compared with major allele homozygotes. Additionally, minor allele heterozygote and homozygote subjects showed reduced cortisol and elevated blood pressure, predicting risk of anxiety and hypertension. Parallel suppression of the conserved brain CDC42 activity by intracerebroventricular ML141 injection caused acute anxiety in mice. We demonstrate that SNPs in miRNA-binding regions could cause expanded downstream effects changing important biological pathways.
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Affiliation(s)
- Geula Hanin
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Shani Shenhar-Tsarfaty
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Nadav Yayon
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | | | - Yau Yin Hoe
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Avenue, 637551, Singapore
| | - Estelle R Bennett
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Ella H Sklan
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dabeeru C Rao
- Division of Biostatistics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | - Tuomo Rankinen
- Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Claude Bouchard
- Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Susana Geifman-Shochat
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Avenue, 637551, Singapore
| | | | - David S Greenberg
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Hermona Soreq
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
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38
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Srivastava AK, Schwartz CE. Intellectual disability and autism spectrum disorders: causal genes and molecular mechanisms. Neurosci Biobehav Rev 2014; 46 Pt 2:161-74. [PMID: 24709068 DOI: 10.1016/j.neubiorev.2014.02.015] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/30/2014] [Accepted: 02/12/2014] [Indexed: 12/19/2022]
Abstract
Intellectual disability (ID) and autism spectrum disorder (ASD) are the most common developmental disorders present in humans. Combined, they affect between 3 and 5% of the population. Additionally, they can be found together in the same individual thereby complicating treatment. The causative factors (genes, epigenetic and environmental) are quite varied and likely interact so as to further complicate the assessment of an individual patient. Nonetheless, much valuable information has been gained by identifying candidate genes for ID or ASD. Understanding the etiology of either ID or ASD is of utmost importance for families. It allows a determination of the risk of recurrence, the possibility of other comorbidity medical problems, the molecular and cellular nature of the pathobiology and hopefully potential therapeutic approaches.
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Affiliation(s)
- Anand K Srivastava
- J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC, USA
| | - Charles E Schwartz
- J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC, USA.
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39
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Soreq L, Guffanti A, Salomonis N, Simchovitz A, Israel Z, Bergman H, Soreq H. Long non-coding RNA and alternative splicing modulations in Parkinson's leukocytes identified by RNA sequencing. PLoS Comput Biol 2014; 10:e1003517. [PMID: 24651478 PMCID: PMC3961179 DOI: 10.1371/journal.pcbi.1003517] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/31/2014] [Indexed: 12/22/2022] Open
Abstract
The continuously prolonged human lifespan is accompanied by increase in neurodegenerative diseases incidence, calling for the development of inexpensive blood-based diagnostics. Analyzing blood cell transcripts by RNA-Seq is a robust means to identify novel biomarkers that rapidly becomes a commonplace. However, there is lack of tools to discover novel exons, junctions and splicing events and to precisely and sensitively assess differential splicing through RNA-Seq data analysis and across RNA-Seq platforms. Here, we present a new and comprehensive computational workflow for whole-transcriptome RNA-Seq analysis, using an updated version of the software AltAnalyze, to identify both known and novel high-confidence alternative splicing events, and to integrate them with both protein-domains and microRNA binding annotations. We applied the novel workflow on RNA-Seq data from Parkinson's disease (PD) patients' leukocytes pre- and post- Deep Brain Stimulation (DBS) treatment and compared to healthy controls. Disease-mediated changes included decreased usage of alternative promoters and N-termini, 5′-end variations and mutually-exclusive exons. The PD regulated FUS and HNRNP A/B included prion-like domains regulated regions. We also present here a workflow to identify and analyze long non-coding RNAs (lncRNAs) via RNA-Seq data. We identified reduced lncRNA expression and selective PD-induced changes in 13 of over 6,000 detected leukocyte lncRNAs, four of which were inversely altered post-DBS. These included the U1 spliceosomal lncRNA and RP11-462G22.1, each entailing sequence complementarity to numerous microRNAs. Analysis of RNA-Seq from PD and unaffected controls brains revealed over 7,000 brain-expressed lncRNAs, of which 3,495 were co-expressed in the leukocytes including U1, which showed both leukocyte and brain increases. Furthermore, qRT-PCR validations confirmed these co-increases in PD leukocytes and two brain regions, the amygdala and substantia-nigra, compared to controls. This novel workflow allows deep multi-level inspection of RNA-Seq datasets and provides a comprehensive new resource for understanding disease transcriptome modifications in PD and other neurodegenerative diseases. Long non-coding RNAs (lncRNAs) comprise a novel, fascinating class of RNAs with largely unknown biological functions. Parkinson's-disease (PD) is the most frequent motor disorder, and Deep-brain-stimulation (DBS) treatment alleviates the symptoms, but early disease biomarkers are still unknown and new future genetic interference targets are urgently needed. Using RNA-sequencing technology and a novel computational workflow for in-depth exploration of whole-transcriptome RNA-seq datasets, we detected and analyzed lncRNAs in sequenced libraries from PD patients' leukocytes pre and post-treatment and the brain, adding this full profile resource of over 7,000 lncRNAs to the few human tissues-derived lncRNA datasets that are currently available. Our study includes sample-specific database construction, detecting disease-derived changes in known and novel lncRNAs, exons and junctions and predicting corresponding changes in Polyadenylation choices, protein domains and miRNA binding sites. We report widespread transcript structure variations at the splice junction and exons levels, including novel exons and junctions and alteration of lncRNAs followed by experimental validation in PD leukocytes and two PD brain regions compared with controls. Our results suggest lncRNAs involvement in neurodegenerative diseases, and specifically PD. This comprehensive workflow will be of use to the increasing number of laboratories producing RNA-Seq data in a wide range of biomedical studies.
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Affiliation(s)
- Lilach Soreq
- Department of Medical Neurobiology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Alessandro Guffanti
- Department of Biological Chemistry, The Life Sciences Institute, The Hebrew University of Jerusalem, Jerusalem, Israel
- Genomnia srl, Lainate, Milan, Italy
| | - Nathan Salomonis
- Department of Pediatrics, Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | | | - Zvi Israel
- The Center for Functional and Restorative Neurosurgery, Department of Neurosurgery, Hadassah University Hospital, Jerusalem, Israel
| | - Hagai Bergman
- Department of Medical Neurobiology, IMRIC, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
- The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Hermona Soreq
- Department of Biological Chemistry, The Life Sciences Institute, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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40
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Fritschy JM, Panzanelli P. GABAAreceptors and plasticity of inhibitory neurotransmission in the central nervous system. Eur J Neurosci 2014; 39:1845-65. [DOI: 10.1111/ejn.12534] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 01/29/2014] [Accepted: 01/29/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Neuroscience Center Zurich; University of Zurich and ETH; Zurich Switzerland
| | - Patrizia Panzanelli
- Department of Neuroscience Rita Levi Montalcini; University of Turin; Turin Italy
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41
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Collybistin activation by GTP-TC10 enhances postsynaptic gephyrin clustering and hippocampal GABAergic neurotransmission. Proc Natl Acad Sci U S A 2013; 110:20795-800. [PMID: 24297911 DOI: 10.1073/pnas.1309078110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
In many brain regions, gephyrin and GABAA receptor clustering at developing inhibitory synapses depends on the guanine nucleotide exchange factor collybistin (Cb). The vast majority of Cb splice variants contain an autoinhibitory src homology 3 domain, and several synaptic proteins are known to bind to this SH3 domain and to thereby activate gephyrin clustering. However, many functional GABAergic synapses form independently of the known Cb-activating proteins, indicating that additional Cb activators must exist. Here we show that the small Rho-like GTPase TC10 stimulates Cb-dependent gephyrin clustering by binding in its active, GTP-bound state to the pleckstrin homology domain of Cb. Overexpression of a constitutively active TC10 variant in neurons causes an increase in the density of synaptic gephyrin clusters and mean miniature inhibitory postsynaptic current amplitudes, whereas a dominant negative TC10 variant has opposite effects. The enhancement of Cb-induced gephyrin clustering by GTP-TC10 does not depend on the guanine nucleotide exchange activity of Cb but involves an interaction that resembles reported interactions of other small GTPases with their effectors. Our data indicate that GTP-TC10 activates the major src homology 3 domain-containing Cb variants by relieving autoinhibition and thus define an alternative GTPase-driven signaling pathway in the genesis of inhibitory synapses.
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42
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Sander B, Tria G, Shkumatov AV, Kim EY, Grossmann JG, Tessmer I, Svergun DI, Schindelin H. Structural characterization of gephyrin by AFM and SAXS reveals a mixture of compact and extended states. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:2050-60. [DOI: 10.1107/s0907444913018714] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 07/05/2013] [Indexed: 11/10/2022]
Abstract
Gephyrin is a trimeric protein involved in the final steps of molybdenum-cofactor (Moco) biosynthesis and in the clustering of inhibitory glycine and GABAAreceptors at postsynaptic specializations. Each protomer consists of stably folded domains (referred to as the G and E domains) located at either terminus and connected by a proteolytically sensitive linker of ∼150 residues. Both terminal domains can oligomerize in their isolated forms; however, in the context of the full-length protein only the G-domain trimer is permanently present, whereas E-domain dimerization is prevented. Atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) reveal a high degree of flexibility in the structure of gephyrin. The results imply an equilibrium between compact and extended conformational states in solution, with a preference for compact states. CD spectroscopy suggests that a partial compaction is achieved by interactions of the linker with the G and E domains. Taken together, the data provide a rationale for the role of the linker in the overall structure and the conformational dynamics of gephyrin.
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43
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Vadodaria KC, Jessberger S. Maturation and integration of adult born hippocampal neurons: signal convergence onto small Rho GTPases. Front Synaptic Neurosci 2013; 5:4. [PMID: 23986696 PMCID: PMC3752586 DOI: 10.3389/fnsyn.2013.00004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 07/29/2013] [Indexed: 01/28/2023] Open
Abstract
Adult neurogenesis, restricted to specific regions in the mammalian brain, represents one of the most interesting forms of plasticity in the mature nervous system. Adult-born hippocampal neurons play important roles in certain forms of learning and memory, and altered hippocampal neurogenesis has been associated with a number of neuropsychiatric diseases such as major depression and epilepsy. Newborn neurons go through distinct developmental steps, from a dividing neurogenic precursor to a synaptically integrated mature neuron. Previous studies have uncovered several molecular signaling pathways involved in distinct steps of this maturational process. In this context, the small Rho GTPases, Cdc42, Rac1, and RhoA have recently been shown to regulate the morphological and synaptic maturation of adult-born dentate granule cells in vivo. Distinct upstream regulators, including growth factors that modulate maturation and integration of newborn neurons have been shown to also recruit the small Rho GTPases. Here we review recent findings and highlight the possibility that small Rho GTPases may act as central assimilators, downstream of critical input onto adult-born hippocampal neurons contributing to their maturation and integration into the existing dentate gyrus (DG) circuitry.
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Affiliation(s)
- Krishna C Vadodaria
- Brain Research Institute, University of Zurich Zurich, Switzerland ; Neuroscience Center Zurich, University of Zurich and ETH Zurich Zurich, Switzerland
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44
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González MI. The possible role of GABAA receptors and gephyrin in epileptogenesis. Front Cell Neurosci 2013; 7:113. [PMID: 23885234 PMCID: PMC3717475 DOI: 10.3389/fncel.2013.00113] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/26/2013] [Indexed: 12/29/2022] Open
Abstract
The term epileptogenesis refers to a dynamic alteration in neuronal excitability that promotes the appearance of spontaneous seizures. Temporal lobe epilepsy, the most common type of acquired epilepsy, often develops after an insult to the brain such as trauma, febrile seizures, encephalitis, or status epilepticus. During the pre-epileptic state (also referred as latent or silent period) there is a plethora of molecular, biochemical, and structural changes that lead to the generation of recurrent spontaneous seizures (or epilepsy). The specific contribution of these alterations to epilepsy development is unclear, but a loss of inhibition has been associated with the increased excitability detected in the latent period. A rapid increase in neuronal hyperexcitability could be due, at least in part, to a decline in the number of physiologically active GABAA receptors (GABAAR). Altered expression of scaffolding proteins involved in the trafficking and anchoring of GABAAR could directly impact the stability of GABAergic synapses and promote a deficiency in inhibitory neurotransmission. Uncovering the molecular mechanisms operating during epileptogenesis and its possible impact on the regulation of GABAAR and scaffolding proteins may offer new targets to prevent the development of epilepsy.
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Affiliation(s)
- Marco I González
- Division of Neurology and Translational Epilepsy Research Program, Department of Pediatrics, University of Colorado School of Medicine Aurora, CO, USA
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45
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Bidkhori G, Narimani Z, Hosseini Ashtiani S, Moeini A, Nowzari-Dalini A, Masoudi-Nejad A. Reconstruction of an integrated genome-scale co-expression network reveals key modules involved in lung adenocarcinoma. PLoS One 2013; 8:e67552. [PMID: 23874428 PMCID: PMC3708931 DOI: 10.1371/journal.pone.0067552] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 05/18/2013] [Indexed: 02/04/2023] Open
Abstract
Our goal of this study was to reconstruct a “genome-scale co-expression network” and find important modules in lung adenocarcinoma so that we could identify the genes involved in lung adenocarcinoma. We integrated gene mutation, GWAS, CGH, array-CGH and SNP array data in order to identify important genes and loci in genome-scale. Afterwards, on the basis of the identified genes a co-expression network was reconstructed from the co-expression data. The reconstructed network was named “genome-scale co-expression network”. As the next step, 23 key modules were disclosed through clustering. In this study a number of genes have been identified for the first time to be implicated in lung adenocarcinoma by analyzing the modules. The genes EGFR, PIK3CA, TAF15, XIAP, VAPB, Appl1, Rab5a, ARF4, CLPTM1L, SP4, ZNF124, LPP, FOXP1, SOX18, MSX2, NFE2L2, SMARCC1, TRA2B, CBX3, PRPF6, ATP6V1C1, MYBBP1A, MACF1, GRM2, TBXA2R, PRKAR2A, PTK2, PGF and MYO10 are among the genes that belong to modules 1 and 22. All these genes, being implicated in at least one of the phenomena, namely cell survival, proliferation and metastasis, have an over-expression pattern similar to that of EGFR. In few modules, the genes such as CCNA2 (Cyclin A2), CCNB2 (Cyclin B2), CDK1, CDK5, CDC27, CDCA5, CDCA8, ASPM, BUB1, KIF15, KIF2C, NEK2, NUSAP1, PRC1, SMC4, SYCE2, TFDP1, CDC42 and ARHGEF9 are present that play a crucial role in cell cycle progression. In addition to the mentioned genes, there are some other genes (i.e. DLGAP5, BIRC5, PSMD2, Src, TTK, SENP2, PSMD2, DOK2, FUS and etc.) in the modules.
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Affiliation(s)
- Gholamreza Bidkhori
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Zahra Narimani
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Saman Hosseini Ashtiani
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ali Moeini
- Department of Algorithms and Computation, College of Engineering, University of Tehran, Tehran, Iran
| | | | - Ali Masoudi-Nejad
- Laboratory of Systems Biology and Bioinformatics (LBB), Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
- * E-mail:
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46
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Ba W, van der Raadt J, Nadif Kasri N. Rho GTPase signaling at the synapse: implications for intellectual disability. Exp Cell Res 2013; 319:2368-74. [PMID: 23769912 DOI: 10.1016/j.yexcr.2013.05.033] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Accepted: 05/29/2013] [Indexed: 12/18/2022]
Abstract
Intellectual disability (ID) imposes a major medical and social-economical problem in our society. It is defined as a global reduction in cognitive and intellectual abilities, associated with impaired social adaptation. The causes of ID are extremely heterogeneous and include non-genetic and genetic changes. Great progress has been made over recent years towards the identification of ID-related genes, resulting in a list of approximately 450 genes. A prominent neuropathological feature of patients with ID is altered dendritic spine morphogenesis. These structural abnormalities, in part, reflect impaired cytoskeleton remodeling and are associated with synaptic dysfunction. The dynamic, actin-rich nature of dendritic spines points to the Rho GTPase family as a central contributor, since they are key regulators of actin dynamics and organization. It is therefore not surprising that mutations in genes encoding regulators and effectors of the Rho GTPases have been associated with ID. This review will focus on the role of Rho GTPase signaling in synaptic structure/function and ID.
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Affiliation(s)
- Wei Ba
- Donders Institute for Brain Cognition and Behavior, Radboud University Nijmegen Medical Center, Department Cognitive Neuroscience, the Netherlands
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47
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Tyagarajan SK, Ghosh H, Yévenes GE, Imanishi SY, Zeilhofer HU, Gerrits B, Fritschy JM. Extracellular signal-regulated kinase and glycogen synthase kinase 3β regulate gephyrin postsynaptic aggregation and GABAergic synaptic function in a calpain-dependent mechanism. J Biol Chem 2013; 288:9634-9647. [PMID: 23408424 DOI: 10.1074/jbc.m112.442616] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Molecular mechanisms of plasticity at GABAergic synapses are currently poorly understood. To identify signaling cascades that converge onto GABAergic postsynaptic density proteins, we performed MS analysis using gephyrin isolated from rat brain and identified multiple novel phosphorylation and acetylation residues on gephyrin. Here, we report the characterization of one of these phosphoresidues, Ser-268, which when dephosphorylated leads to the formation of larger postsynaptic scaffolds. Using a combination of mutagenesis, pharmacological treatment, and biochemical assays, we identify ERK as the kinase phosphorylating Ser-268 and describe a functional interaction between residues Ser-268 and Ser-270. We further demonstrate that alterations in gephyrin clustering via ERK modulation are reflected by amplitude and frequency changes in miniature GABAergic postsynaptic currents. We unravel novel mechanisms for activity- and ERK-dependent calpain action on gephyrin, which are likely relevant in the context of cellular signaling affecting GABAergic transmission and homeostatic synaptic plasticity in pathology.
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Affiliation(s)
- Shiva K Tyagarajan
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland.
| | - Himanish Ghosh
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland
| | - Gonzalo E Yévenes
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland
| | - Susumu Y Imanishi
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, 20520 Turku, Finland
| | - Hanns Ulrich Zeilhofer
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland; Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, 8093 Switzerland
| | | | - Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, 8057 Zurich, Switzerland; Neuroscience Center Zurich, Zurich, 8057 Switzerland
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48
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Miller MB, Yan Y, Eipper BA, Mains RE. Neuronal Rho GEFs in synaptic physiology and behavior. Neuroscientist 2013; 19:255-73. [PMID: 23401188 DOI: 10.1177/1073858413475486] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the mammalian brain, the majority of excitatory synapses are housed in micron-sized dendritic protrusions called spines, which can undergo rapid changes in shape and number in response to increased or decreased synaptic activity. These dynamic alterations in dendritic spines require precise control of the actin cytoskeleton. Within spines, multidomain Rho guanine nucleotide exchange factors (Rho GEFs) coordinate activation of their target Rho GTPases by a variety of pathways. In this review, we focus on the handful of disease-related Rho GEFs (Kalirin; Trio; Tiam1; P-Rex1,2; RasGRF1,2; Collybistin) localized at synapses and known to affect electrophysiology, spine morphology, and animal behavior. The goal is to integrate structure/function studies with measurements of synaptic function and behavioral phenotypes in animal models.
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Affiliation(s)
- Megan B Miller
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030-3401, USA
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49
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A comprehensive small interfering RNA screen identifies signaling pathways required for gephyrin clustering. J Neurosci 2013; 32:14821-34. [PMID: 23077067 DOI: 10.1523/jneurosci.1261-12.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The postsynaptic scaffold protein gephyrin is clustered at inhibitory synapses and serves for the stabilization of GABA(A) receptors. Here, a comprehensive kinome-wide siRNA screen in a human HeLa cell-based model for gephyrin clustering was used to identify candidate protein kinases implicated in the stabilization of gephyrin clusters. As a result, 12 hits were identified including FGFR1 (FGF receptor 1), TrkB, and TrkC as well as components of the MAPK and mammalian target of rapamycin (mTOR) pathways. For confirmation, the impact of these hits on gephyrin clustering was analyzed in rat primary hippocampal neurons. We found that brain-derived neurotrophic factor (BDNF) acts on gephyrin clustering through MAPK signaling, and this process may be controlled by the MAPK signaling antagonist sprouty2. BDNF signaling through phosphatidylinositol 3-kinase (PI3K)-Akt also activates mTOR and represses GSK3β, which was previously shown to reduce gephyrin clustering. Gephyrin is associated with inactive mTOR and becomes released upon BDNF-dependent mTOR activation. In primary neurons, a reduction in the number of gephyrin clusters due to manipulation of the BDNF-mTOR signaling is associated with reduced GABA(A) receptor clustering, suggesting functional impairment of GABA signaling. Accordingly, application of the mTOR antagonist rapamycin leads to disinhibition of neuronal networks as measured on microelectrode arrays. In conclusion, we provide evidence that BDNF regulates gephyrin clustering via MAPK as well as PI3K-Akt-mTOR signaling.
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50
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Fritschy JM, Panzanelli P, Tyagarajan SK. Molecular and functional heterogeneity of GABAergic synapses. Cell Mol Life Sci 2012; 69:2485-99. [PMID: 22314501 PMCID: PMC11115047 DOI: 10.1007/s00018-012-0926-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2011] [Revised: 01/16/2012] [Accepted: 01/19/2012] [Indexed: 01/07/2023]
Abstract
Knowledge of the functional organization of the GABAergic system, the main inhibitory neurotransmitter system, in the CNS has increased remarkably in recent years. In particular, substantial progress has been made in elucidating the molecular mechanisms underlying the formation and plasticity of GABAergic synapses. Evidence available ascribes a key role to the cytoplasmic protein gephyrin to form a postsynaptic scaffold anchoring GABA(A) receptors along with other transmembrane proteins and signaling molecules in the postsynaptic density. However, the mechanisms of gephyrin scaffolding remain elusive, notably because gephyrin can auto-aggregate spontaneously and lacks PDZ protein interaction domains found in a majority of scaffolding proteins. In addition, the structural diversity of GABA(A) receptors, which are pentameric channels encoded by a large family of subunits, has been largely overlooked in these studies. Finally, the role of the dystrophin-glycoprotein complex, present in a subset of GABAergic synapses in cortical structures, remains ill-defined. In this review, we discuss recent results derived mainly from the analysis of mutant mice lacking a specific GABA(A) receptor subtype or a core protein of the GABAergic postsynaptic density (neuroligin-2, collybistin), highlighting the molecular diversity of GABAergic synapses and its relevance for brain plasticity and function. In addition, we discuss the contribution of the dystrophin-glycoprotein complex to the molecular and functional heterogeneity of GABAergic synapses.
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Affiliation(s)
- Jean-Marc Fritschy
- Institute of Pharmacology and Toxicology, University of Zurich, Switzerland.
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