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Arora I, Mal P, Arora P, Paul A, Kumar M. GABAergic implications in anxiety and related disorders. Biochem Biophys Res Commun 2024; 724:150218. [PMID: 38865810 DOI: 10.1016/j.bbrc.2024.150218] [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: 02/28/2024] [Revised: 05/05/2024] [Accepted: 06/02/2024] [Indexed: 06/14/2024]
Abstract
Evidence indicates that anxiety disorders arise from an imbalance in the functioning of brain circuits that govern the modulation of emotional responses to possibly threatening stimuli. The circuits under consideration in this context include the amygdala's bottom-up activity, which signifies the existence of stimuli that may be seen as dangerous. Moreover, these circuits encompass top-down regulatory processes that originate in the prefrontal cortex, facilitating the communication of the emotional significance associated with the inputs. Diverse databases (e.g., Pubmed, ScienceDirect, Web of Science, Google Scholar) were searched for literature using a combination of different terms e.g., "anxiety", "stress", "neuroanatomy", and "neural circuits", etc. A decrease in GABAergic activity is present in both anxiety disorders and severe depression. Research on cerebral functional imaging in depressive individuals has shown reduced levels of GABA within the cortical regions. Additionally, animal studies demonstrated that a reduction in the expression of GABAA/B receptors results in a behavioral pattern resembling anxiety. The amygdala consists of inhibitory networks composed of GABAergic interneurons, responsible for modulating anxiety responses in both normal and pathological conditions. The GABAA receptor has allosteric sites (e.g., α/γ, γ/β, and α/β) which enable regulation of neuronal inhibition in the amygdala. These sites serve as molecular targets for anxiolytic medications such as benzodiazepine and barbiturates. Alterations in the levels of naturally occurring regulators of these allosteric sites, along with alterations to the composition of the GABAA receptor subunits, could potentially act as mechanisms via which the extent of neuronal inhibition is diminished in pathological anxiety disorders.
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Affiliation(s)
- Indu Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Pankaj Mal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Poonam Arora
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Anushka Paul
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Manish Kumar
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
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2
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Li S, Gao L, Liu C, Guo H, Yu J. Biomimetic Neuromorphic Sensory System via Electrolyte Gated Transistors. SENSORS (BASEL, SWITZERLAND) 2024; 24:4915. [PMID: 39123962 PMCID: PMC11314768 DOI: 10.3390/s24154915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2024] [Revised: 07/26/2024] [Accepted: 07/27/2024] [Indexed: 08/12/2024]
Abstract
Biomimetic neuromorphic sensing systems, inspired by the structure and function of biological neural networks, represent a major advancement in the field of sensing technology and artificial intelligence. This review paper focuses on the development and application of electrolyte gated transistors (EGTs) as the core components (synapses and neuros) of these neuromorphic systems. EGTs offer unique advantages, including low operating voltage, high transconductance, and biocompatibility, making them ideal for integrating with sensors, interfacing with biological tissues, and mimicking neural processes. Major advances in the use of EGTs for neuromorphic sensory applications such as tactile sensors, visual neuromorphic systems, chemical neuromorphic systems, and multimode neuromorphic systems are carefully discussed. Furthermore, the challenges and future directions of the field are explored, highlighting the potential of EGT-based biomimetic systems to revolutionize neuromorphic prosthetics, robotics, and human-machine interfaces. Through a comprehensive analysis of the latest research, this review is intended to provide a detailed understanding of the current status and future prospects of biomimetic neuromorphic sensory systems via EGT sensing and integrated technologies.
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Affiliation(s)
| | | | | | | | - Junsheng Yu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, China
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3
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Developmental Inhibitory Changes in the Primary Somatosensory Cortex of the Stargazer Mouse Model of Absence Epilepsy. Biomolecules 2023; 13:biom13010186. [PMID: 36671571 PMCID: PMC9856073 DOI: 10.3390/biom13010186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 01/08/2023] [Accepted: 01/11/2023] [Indexed: 01/19/2023] Open
Abstract
Childhood absence epilepsy seizures arise in the cortico-thalamocortical network due to multiple cellular and molecular mechanisms, which are still under investigation. Understanding the precise mechanisms is imperative given that treatment fails in ~30% of patients while adverse neurological sequelae remain common. Impaired GABAergic neurotransmission is commonly reported in research models investigating these mechanisms. Recently, we reported a region-specific reduction in the whole-tissue and synaptic GABAA receptor (GABAAR) α1 subunit and an increase in whole-tissue GAD65 in the primary somatosensory cortex (SoCx) of the adult epileptic stargazer mouse compared with its non-epileptic (NE) littermate. The current study investigated whether these changes occurred prior to the onset of seizures on postnatal days (PN) 17-18, suggesting a causative role. Synaptic and cytosolic fractions were biochemically isolated from primary SoCx lysates followed by semiquantitative Western blot analyses for GABAAR α1 and GAD65. We found no significant changes in synaptic GABAAR α1 and cytosolic GAD65 in the primary SoCx of the stargazer mice at the critical developmental stages of PN 7-9, 13-15, and 17-18. This indicates that altered levels of GABAAR α1 and GAD65 in adult mice do not directly contribute to the initial onset of absence seizures but are a later consequence of seizure activity.
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Altered GABA A Receptor Expression in the Primary Somatosensory Cortex of a Mouse Model of Genetic Absence Epilepsy. Int J Mol Sci 2022; 23:ijms232415685. [PMID: 36555327 PMCID: PMC9778655 DOI: 10.3390/ijms232415685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/26/2022] [Accepted: 12/07/2022] [Indexed: 12/14/2022] Open
Abstract
Absence seizures are hyperexcitations within the cortico-thalamocortical (CTC) network, however the underlying causative mechanisms at the cellular and molecular level are still being elucidated and appear to be multifactorial. Dysfunctional feed-forward inhibition (FFI) is implicated as one cause of absence seizures. Previously, we reported altered excitation onto parvalbumin-positive (PV+) interneurons in the CTC network of the stargazer mouse model of absence epilepsy. In addition, downstream changes in GABAergic neurotransmission have also been identified in this model. Our current study assessed whether dysfunctional FFI affects GABAA receptor (GABAAR) subunit expression in the stargazer primary somatosensory cortex (SoCx). Global tissue expression of GABAAR subunits α1, α3, α4, α5, β2, β3, γ2 and δ were assessed using Western blotting (WB), while biochemically isolated subcellular fractions were assessed for the α and δ subunits. We found significant reductions in tissue and synaptic expression of GABAAR α1, 18% and 12.2%, respectively. However, immunogold-cytochemistry electron microscopy (ICC-EM), conducted to assess GABAAR α1 specifically at synapses between PV+ interneurons and their targets, showed no significant difference. These data demonstrate a loss of phasic GABAAR α1, indicating altered GABAergic inhibition which, coupled with dysfunctional FFI, could be one mechanism contributing to the generation or maintenance of absence seizures.
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Wang YJ, Di XJ, Mu TW. Quantitative interactome proteomics identifies a proteostasis network for GABA A receptors. J Biol Chem 2022; 298:102423. [PMID: 36030824 PMCID: PMC9493394 DOI: 10.1016/j.jbc.2022.102423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 08/17/2022] [Accepted: 08/19/2022] [Indexed: 11/29/2022] Open
Abstract
Gamma-aminobutyric acid type A (GABAA) receptors are the primary inhibitory neurotransmitter-gated ion channels in the mammalian central nervous system. Maintenance of GABAA receptor protein homeostasis (proteostasis) in cells utilizing its interacting proteins is essential for the function of GABAA receptors. However, how the proteostasis network orchestrates GABAA receptor biogenesis in the endoplasmic reticulum is not well understood. Here, we employed a proteomics-based approach to systematically identify the interactomes of GABAA receptors. We carried out a quantitative immunoprecipitation-tandem mass spectrometry analysis utilizing stable isotope labeling by amino acids in cell culture. Furthermore, we performed comparative proteomics by using both WT α1 subunit and a misfolding-prone α1 subunit carrying the A322D variant as the bait proteins. We identified 125 interactors for WT α1-containing receptors, 105 proteins for α1(A322D)-containing receptors, and 54 overlapping proteins within these two interactomes. Our bioinformatics analysis identified potential GABAA receptor proteostasis network components, including chaperones, folding enzymes, trafficking factors, and degradation factors, and we assembled a model of their potential involvement in the cellular folding, degradation, and trafficking pathways for GABAA receptors. In addition, we verified endogenous interactions between α1 subunits and selected interactors by using coimmunoprecipitation in mouse brain homogenates. Moreover, we showed that TRIM21 (tripartite motif containing-21), an E3 ubiquitin ligase, positively regulated the degradation of misfolding-prone α1(A322D) subunits selectively. This study paves the way for understanding the molecular mechanisms as well as fine-tuning of GABAA receptor proteostasis to ameliorate related neurological diseases such as epilepsy.
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Affiliation(s)
- Ya-Juan Wang
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA; Center for Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
| | - Xiao-Jing Di
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
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Nagayach A, Ghafari M, Zhao Y, Collins GS, Singh A, Geller AI. Connected neurons in multiple neocortical areas, comprising parallel circuits, encode essential information for visual shape learning. J Chem Neuroanat 2021; 118:102024. [PMID: 34492329 DOI: 10.1016/j.jchemneu.2021.102024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 08/28/2021] [Accepted: 09/02/2021] [Indexed: 11/25/2022]
Abstract
Neocortical areas comprised of multiple neuronal circuits which are encoded with innumerable advanced cognitive tasks. Studies focused on neuronal network and synaptic plasticity has hypothesized that every specific neuron and the circuit process the explicit essential information for the specific tasks. However, the structure of these circuits and the involved critical neurons remain to be elucidated. Considering our previous studies, showing the specificity of rat postrhinal cortex comprising specific neuronal circuit for encoding both the learning and recall of shape discrimination through a fast neurotransmitter release from the transduced neurons, here we have demonstrated that postsynaptic neurons in two distinct areas, perirhinal cortex and the ventral temporal association areas are required for the specific visual shape discriminations learning. The constitutively active PKC was delivered into neuronal cells in postrhinal cortex, and the animals were allowed to learn the new shape discriminations, and then the silencing siRNA was delivered into postsynaptic neurons in either perirhinal cortex or ventral temporal association areas, using a novel technology for gene transfer into connected neurons. We observed that expression of the siRNA caused the deficits in visual performance, via blocking the activity in the neurons, as displayed by activity-dependent gene imaging, and also subsequently obstructed the activation of specific signaling pathways required for further learning, and dendritic protein synthesis and CREB. Thus, ratifying the conclusion that the two parallel circuits are both required for the visual shape discrimination learning.
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Affiliation(s)
- Aarti Nagayach
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States.
| | - Maryam Ghafari
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States
| | - Yinghong Zhao
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States
| | - Grant S Collins
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States
| | - Anshuman Singh
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States
| | - Alfred I Geller
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States; Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, United States
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7
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Fingleton E, Li Y, Roche KW. Advances in Proteomics Allow Insights Into Neuronal Proteomes. Front Mol Neurosci 2021; 14:647451. [PMID: 33935646 PMCID: PMC8084103 DOI: 10.3389/fnmol.2021.647451] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 03/25/2021] [Indexed: 11/29/2022] Open
Abstract
Protein–protein interaction networks and signaling complexes are essential for normal brain function and are often dysregulated in neurological disorders. Nevertheless, unraveling neuron- and synapse-specific proteins interaction networks has remained a technical challenge. New techniques, however, have allowed for high-resolution and high-throughput analyses, enabling quantification and characterization of various neuronal protein populations. Over the last decade, mass spectrometry (MS) has surfaced as the primary method for analyzing multiple protein samples in tandem, allowing for the precise quantification of proteomic data. Moreover, the development of sophisticated protein-labeling techniques has given MS a high temporal and spatial resolution, facilitating the analysis of various neuronal substructures, cell types, and subcellular compartments. Recent studies have leveraged these novel techniques to reveal the proteomic underpinnings of well-characterized neuronal processes, such as axon guidance, long-term potentiation, and homeostatic plasticity. Translational MS studies have facilitated a better understanding of complex neurological disorders, such as Alzheimer’s disease (AD), Schizophrenia (SCZ), and Autism Spectrum Disorder (ASD). Proteomic investigation of these diseases has not only given researchers new insight into disease mechanisms but has also been used to validate disease models and identify new targets for research.
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Affiliation(s)
- Erin Fingleton
- National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, United States
| | - Yan Li
- National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, United States
| | - Katherine W Roche
- National Institute of Neurological Disorders and Stroke (NINDS), Bethesda, MD, United States
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8
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Xu Y, Song X, Wang D, Wang Y, Li P, Li J. Proteomic insights into synaptic signaling in the brain: the past, present and future. Mol Brain 2021; 14:37. [PMID: 33596935 PMCID: PMC7888154 DOI: 10.1186/s13041-021-00750-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/09/2021] [Indexed: 12/29/2022] Open
Abstract
Chemical synapses in the brain connect neurons to form neural circuits, providing the structural and functional bases for neural communication. Disrupted synaptic signaling is closely related to a variety of neurological and psychiatric disorders. In the past two decades, proteomics has blossomed as a versatile tool in biological and biomedical research, rendering a wealth of information toward decoding the molecular machinery of life. There is enormous interest in employing proteomic approaches for the study of synapses, and substantial progress has been made. Here, we review the findings of proteomic studies of chemical synapses in the brain, with special attention paid to the key players in synaptic signaling, i.e., the synaptic protein complexes and their post-translational modifications. Looking toward the future, we discuss the technological advances in proteomics such as data-independent acquisition mass spectrometry (DIA-MS), cross-linking in combination with mass spectrometry (CXMS), and proximity proteomics, along with their potential to untangle the mystery of how the brain functions at the molecular level. Last but not least, we introduce the newly developed synaptomic methods. These methods and their successful applications marked the beginnings of the synaptomics era.
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Affiliation(s)
- Yalan Xu
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Xiuyue Song
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Dong Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Yin Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Peifeng Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China
| | - Jing Li
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, Medical College, Qingdao University, Qingdao, 266021, China.
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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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Han W, Shepard RD, Lu W. Regulation of GABA ARs by Transmembrane Accessory Proteins. Trends Neurosci 2021; 44:152-165. [PMID: 33234346 PMCID: PMC7855156 DOI: 10.1016/j.tins.2020.10.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/08/2020] [Accepted: 10/20/2020] [Indexed: 12/13/2022]
Abstract
The vast majority of fast inhibitory transmission in the brain is mediated by GABA acting on GABAA receptors (GABAARs), which provides inhibitory balance to excitatory drive and controls neuronal output. GABAARs are also effectively targeted by clinically important drugs for treatment in a number of neurological disorders. It has long been hypothesized that function and pharmacology of GABAARs are determined by the channel pore-forming subunits. However, recent studies have provided new dimensions in studying GABAARs due to several transmembrane proteins that interact with GABAARs and modulate their trafficking and function. In this review, we summarize recent findings on these novel GABAAR transmembrane regulators and highlight a potential avenue to develop new GABAAR psychopharmacology by targeting these receptor-associated membrane proteins.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ryan D Shepard
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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11
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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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12
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Minehart JA, Speer CM. A Picture Worth a Thousand Molecules-Integrative Technologies for Mapping Subcellular Molecular Organization and Plasticity in Developing Circuits. Front Synaptic Neurosci 2021; 12:615059. [PMID: 33469427 PMCID: PMC7813761 DOI: 10.3389/fnsyn.2020.615059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
A key challenge in developmental neuroscience is identifying the local regulatory mechanisms that control neurite and synaptic refinement over large brain volumes. Innovative molecular techniques and high-resolution imaging tools are beginning to reshape our view of how local protein translation in subcellular compartments drives axonal, dendritic, and synaptic development and plasticity. Here we review recent progress in three areas of neurite and synaptic study in situ-compartment-specific transcriptomics/translatomics, targeted proteomics, and super-resolution imaging analysis of synaptic organization and development. We discuss synergies between sequencing and imaging techniques for the discovery and validation of local molecular signaling mechanisms regulating synaptic development, plasticity, and maintenance in circuits.
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Affiliation(s)
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD, United States
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13
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Han W, Li J, Pelkey KA, Pandey S, Chen X, Wang YX, Wu K, Ge L, Li T, Castellano D, Liu C, Wu LG, Petralia RS, Lynch JW, McBain CJ, Lu W. Shisa7 is a GABA A receptor auxiliary subunit controlling benzodiazepine actions. Science 2020; 366:246-250. [PMID: 31601770 DOI: 10.1126/science.aax5719] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 08/27/2019] [Indexed: 12/20/2022]
Abstract
The function and pharmacology of γ-aminobutyric acid type A receptors (GABAARs) are of great physiological and clinical importance and have long been thought to be determined by the channel pore-forming subunits. We discovered that Shisa7, a single-passing transmembrane protein, localizes at GABAergic inhibitory synapses and interacts with GABAARs. Shisa7 controls receptor abundance at synapses and speeds up the channel deactivation kinetics. Shisa7 also potently enhances the action of diazepam, a classic benzodiazepine, on GABAARs. Genetic deletion of Shisa7 selectively impairs GABAergic transmission and diminishes the effects of diazepam in mice. Our data indicate that Shisa7 regulates GABAAR trafficking, function, and pharmacology and reveal a previously unknown molecular interaction that modulates benzodiazepine action in the brain.
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Affiliation(s)
- Wenyan Han
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jun Li
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kenneth A Pelkey
- Cellular and Synaptic Neuroscience Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Saurabh Pandey
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiumin Chen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ya-Xian Wang
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kunwei Wu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lihao Ge
- Synaptic Transmission Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tianming Li
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Castellano
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chengyu Liu
- Transgenetic Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ling-Gang Wu
- Synaptic Transmission Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ronald S Petralia
- Advanced Imaging Core, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Joseph W Lynch
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Chris J McBain
- Cellular and Synaptic Neuroscience Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Wei Lu
- Synapse and Neural Circuit Research Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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14
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Kiss E, Groeneweg F, Gorgas K, Schlicksupp A, Kins S, Kirsch J, Kuhse J. Amyloid-β Fosters p35/CDK5 Signaling Contributing to Changes of Inhibitory Synapses in Early Stages of Cerebral Amyloidosis. J Alzheimers Dis 2020; 74:1167-1187. [DOI: 10.3233/jad-190976] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Eva Kiss
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
- Department of Cellular and Molecular Biology, “Emil Palade” University of Medicine, Pharmacy, Science and Technology of Târgu Mureş, Târgu Mureş, Romania
| | - Femke Groeneweg
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Karin Gorgas
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Andrea Schlicksupp
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Stefan Kins
- Department of Human Biology and Human Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Joachim Kirsch
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Jochen Kuhse
- Institute of Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
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15
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Ultrastructural and molecular features of excitatory and glutamatergic synapses. The auditory nerve synapses. VITAMINS AND HORMONES 2020; 114:23-51. [PMID: 32723545 DOI: 10.1016/bs.vh.2020.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glutamatergic synapses mediate fast synaptic transmission in the central nervous system. New developments highlight the importance of the synapse structural and molecular remodeling during development, aging and in neurological disorders. This chapter summarizes key structural and molecular aspects of the presynaptic and postsynaptic components of glutamatergic synapses in the brain. In addition, this chapter describes how the structure of the postsynaptic density and ionotropic glutamate content contribute to the function of auditory nerve synapses in the lower auditory brainstem.
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16
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Uezu A, Hisey E, Kobayashi Y, Gao Y, Bradshaw TWA, Devlin P, Rodriguiz R, Tata PR, Soderling S. Essential role for InSyn1 in dystroglycan complex integrity and cognitive behaviors in mice. eLife 2019; 8:e50712. [PMID: 31829939 PMCID: PMC6944460 DOI: 10.7554/elife.50712] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 12/11/2019] [Indexed: 02/06/2023] Open
Abstract
Human mutations in the dystroglycan complex (DGC) result in not only muscular dystrophy but also cognitive impairments. However, the molecular architecture critical for the synaptic organization of the DGC in neurons remains elusive. Here, we report Inhibitory Synaptic protein 1 (InSyn1) is a critical component of the DGC whose loss alters the composition of the GABAergic synapses, excitatory/inhibitory balance in vitro and in vivo, and cognitive behavior. Association of InSyn1 with DGC subunits is required for InSyn1 synaptic localization. InSyn1 null neurons also show a significant reduction in DGC and GABA receptor distribution as well as abnormal neuronal network activity. Moreover, InSyn1 null mice exhibit elevated neuronal firing patterns in the hippocampus and deficits in fear conditioning memory. Our results support the dysregulation of the DGC at inhibitory synapses and altered neuronal network activity and specific cognitive tasks via loss of a novel component, InSyn1.
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Affiliation(s)
- Akiyoshi Uezu
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
| | - Erin Hisey
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
| | | | - Yudong Gao
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
| | - Tyler WA Bradshaw
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
| | - Patrick Devlin
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
| | - Ramona Rodriguiz
- Department of Psychiatry and Behavioral SciencesDuke University Medical SchoolDurhamUnited States
- Mouse Behavioral and Neuroendocrine Analysis Core FacilityDuke University Medical SchoolDurhamUnited States
| | | | - Scott Soderling
- Department of Cell BiologyDuke University Medical SchoolDurhamUnited States
- Department of NeurobiologyDuke University Medical SchoolDurhamUnited States
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17
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Guha D, Lorenz DR, Misra V, Chettimada S, Morgello S, Gabuzda D. Proteomic analysis of cerebrospinal fluid extracellular vesicles reveals synaptic injury, inflammation, and stress response markers in HIV patients with cognitive impairment. J Neuroinflammation 2019; 16:254. [PMID: 31805958 PMCID: PMC6896665 DOI: 10.1186/s12974-019-1617-y] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 10/10/2019] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Extracellular vesicles (EVs) are nano-sized particles present in most body fluids including cerebrospinal fluid (CSF). Little is known about CSF EV proteins in HIV+ individuals. Here, we characterize the CSF EV proteome in HIV+ subjects and its relationship to neuroinflammation, stress responses, and HIV-associated neurocognitive disorders (HAND). METHODS CSF EVs isolated from 20 HIV+ subjects with (n = 10) or without (n = 10) cognitive impairment were characterized by electron microscopy, nanoparticle tracking analysis, immunoblotting, and untargeted LC/MS/MS mass spectrometry. Functional annotation was performed by gene ontology (GO) mapping and expression annotation using Biobase Transfac and PANTHER software. Cultured astrocytic U87 cells were treated with hydrogen peroxide for 4 h to induce oxidative stress and EVs isolated by ultracentrifugation. Selected markers of astrocytes (GFAP, GLUL), inflammation (CRP), and stress responses (PRDX2, PARK7, HSP70) were evaluated in EVs released by U87 cells following induction of oxidative stress and in CSF EVs from HIV+ patients by immunoblotting. RESULTS Mass spectrometry identified 2727 and 1626 proteins in EV fractions and EV-depleted CSF samples, respectively. CSF EV fractions were enriched with exosomal markers including Alix, syntenin, tetraspanins, and heat-shock proteins and a subset of neuronal, astrocyte, oligodendrocyte, and choroid plexus markers, in comparison to EV-depleted CSF. Proteins related to synapses, immune/inflammatory responses, stress responses, metabolic processes, mitochondrial functions, and blood-brain barrier were also identified in CSF EV fractions by GO mapping. HAND subjects had higher abundance of CSF EVs and proteins mapping to GO terms for synapses, glial cells, inflammation, and stress responses compared to those without HAND. GFAP, GLUL, CRP, PRDX2, PARK7, and HSP70 were confirmed by immunoblotting of CSF EVs from subjects with HAND and were also detected in EVs released by U87 cells under oxidative stress. CONCLUSIONS These findings suggest that CSF EVs derived from neurons, glial cells, and choroid plexus carry synaptic, immune/inflammation-related, and stress response proteins in HIV+ individuals with cognitive impairment, representing a valuable source for biomarker discovery.
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Affiliation(s)
- Debjani Guha
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, CLS 1010, 450 Brookline Ave, Boston, MA, 02215, USA
| | - David R Lorenz
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, CLS 1010, 450 Brookline Ave, Boston, MA, 02215, USA
| | - Vikas Misra
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, CLS 1010, 450 Brookline Ave, Boston, MA, 02215, USA
| | - Sukrutha Chettimada
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, CLS 1010, 450 Brookline Ave, Boston, MA, 02215, USA
| | - Susan Morgello
- Departments of Neurology, Neuroscience and Pathology, Mount Sinai Medical Center, New York, NY, USA
| | - Dana Gabuzda
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, CLS 1010, 450 Brookline Ave, Boston, MA, 02215, USA. .,Department of Neurology, Harvard Medical School, Boston, MA, USA.
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18
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Nagayach A, Singh A, De Blas AL, Geller AI. Delivery of different genes into pre- and post-synaptic neocortical interneurons connected by GABAergic synapses. PLoS One 2019; 14:e0217094. [PMID: 31125364 PMCID: PMC6534327 DOI: 10.1371/journal.pone.0217094] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 05/03/2019] [Indexed: 12/13/2022] Open
Abstract
Local neocortical circuits play critical roles in information processing, including synaptic plasticity, circuit physiology, and learning, and GABAergic inhibitory interneurons have key roles in these circuits. Moreover, specific neurological disorders, including schizophrenia and autism, are associated with deficits in GABAergic transmission in these circuits. GABAergic synapses represent a small fraction of neocortical synapses, and are embedded in complex local circuits that contain many neuron and synapse types. Thus, it is challenging to study the physiological roles of GABAergic inhibitory interneurons and their synapses, and to develop treatments for the specific disorders caused by dysfunction at these GABAergic synapses. To these ends, we report a novel technology that can deliver different genes into pre- and post-synaptic neocortical interneurons connected by a GABAergic synapse: First, standard gene transfer into the presynaptic neurons delivers a synthetic peptide neurotransmitter, containing three domains, a dense core vesicle sorting domain, a GABAA receptor-binding domain, a single-chain variable fragment anti-GABAA ß2 or ß3, and the His tag. Second, upon release, this synthetic peptide neurotransmitter binds to GABAA receptors on the postsynaptic neurons. Third, as the synthetic peptide neurotransmitter contains the His tag, antibody-mediated, targeted gene transfer using anti-His tag antibodies is selective for these neurons. We established this technology by expressing the synthetic peptide neurotransmitter in GABAergic neurons in the middle layers of postrhinal cortex, and the delivering the postsynaptic vector into connected GABAergic neurons in the upper neocortical layers. Targeted gene transfer was 61% specific for the connected neurons, but untargeted gene transfer was only 21% specific for these neurons. This technology may support studies on the roles of GABAergic inhibitory interneurons in circuit physiology and learning, and support gene therapy treatments for specific disorders associated with deficits at GABAergic synapses.
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Affiliation(s)
- Aarti Nagayach
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Anshuman Singh
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Angel L. De Blas
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Alfred I. Geller
- Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
- Department of Pharmacology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
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19
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Tomita S. Molecular constituents and localization of the ionotropic GABA receptor complex in vivo. Curr Opin Neurobiol 2019; 57:81-86. [PMID: 30784980 DOI: 10.1016/j.conb.2019.01.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 01/14/2019] [Indexed: 01/24/2023]
Abstract
The ionotropic GABA receptor (GABAAR) mediates fast inhibition in the brain. The GABAAR pore-forming (α, β, and non-α/β) subunits were isolated approximately 30 years ago and have since been the focus of extensive studies. As a result, many properties of GABAARs, including subunit assembly and channel and pharmacological properties, have been discovered. However, several of the underlying mechanisms such as the process for the synaptic localization of GABAARs remain unsolved. A reinvestigation of native GABAAR complexes in the brain and primary neurons identified two major molecular constituents, namely, the transmembrane GARLH/LHFPL protein family and the inhibitory synaptic protein neuroligin 2. This identification of the principal components of native receptor complexes may provide new mechanistic insight on receptor regulation.
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Affiliation(s)
- Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06510, United States.
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20
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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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21
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Abstract
Two anatomically and functionally distinct types of synapses are present in the central nervous system, excitatory synapses, and inhibitory synapses. Purification and analysis of the protein complex at the excitatory postsynapses have led to fundamental insights into neurobiology. In contrast, the biochemical purification and analysis of the inhibitory postsynaptic density have been largely intractable. The recently developed method called BioID employs the biotin ligase mutant, BirA*, fused to a bait protein to label and capture proximal proteins. We adapted the BioID approach to enable in vivo BioID, or iBioID of inhibitory synaptic complexes in the mouse brain. This protocol describes the iBioID method to allow synaptic bait proteins to target synaptic complexes, label, and purify biotinylated proteins from the mouse brain. This technique can be easily adapted to target other substructures in vivo that have been difficult to purify and analyze in the past.
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Affiliation(s)
- Akiyoshi Uezu
- The Department of Cell Biology, Duke University Medical School, Durham, NC, USA.
| | - Scott Soderling
- The Department of Cell Biology and Neurobiology, Duke University Medical School, Durham, NC, USA
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22
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Cijsouw T, Ramsey AM, Lam TT, Carbone BE, Blanpied TA, Biederer T. Mapping the Proteome of the Synaptic Cleft through Proximity Labeling Reveals New Cleft Proteins. Proteomes 2018; 6:proteomes6040048. [PMID: 30487426 PMCID: PMC6313906 DOI: 10.3390/proteomes6040048] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 11/15/2018] [Accepted: 11/18/2018] [Indexed: 12/21/2022] Open
Abstract
Synapses are specialized neuronal cell-cell contacts that underlie network communication in the mammalian brain. Across neuronal populations and circuits, a diverse set of synapses is utilized, and they differ in their molecular composition to enable heterogenous connectivity patterns and functions. In addition to pre- and post-synaptic specializations, the synaptic cleft is now understood to be an integral compartment of synapses that contributes to their structural and functional organization. Aiming to map the cleft proteome, this study applied a peroxidase-mediated proximity labeling approach and used the excitatory synaptic cell adhesion protein SynCAM 1 fused to horseradish peroxidase (HRP) as a reporter in cultured cortical neurons. This reporter marked excitatory synapses as measured by confocal microcopy and was targeted to the edge zone of the synaptic cleft as determined using 3D dSTORM super-resolution imaging. Proximity labeling with a membrane-impermeant biotin-phenol compound restricted labeling to the cell surface, and Label-Free Quantitation (LFQ) mass spectrometry combined with ratiometric HRP tagging of membrane vs. synaptic surface proteins was used to identify the proteomic content of excitatory clefts. Novel cleft candidates were identified, and Receptor-type tyrosine-protein phosphatase zeta was selected and successfully validated. This study supports the robust applicability of peroxidase-mediated proximity labeling for synaptic cleft proteomics and its potential for understanding synapse heterogeneity in health and changes in diseases such as psychiatric disorders and addiction.
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Affiliation(s)
- Tony Cijsouw
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA.
| | - Austin M Ramsey
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - TuKiet T Lam
- Yale/NIDA Neuroproteomics Center, New Haven, CT 06511, USA.
- W.M. Keck Biotechnology Resource Laboratory, Yale University School of Medicine, 300 George Street, New Haven, CT 06511, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Beatrice E Carbone
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA.
| | - Thomas A Blanpied
- Department of Physiology and Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Thomas Biederer
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA.
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23
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Uncovering Discrete Synaptic Proteomes to Understand Neurological Disorders. Proteomes 2018; 6:proteomes6030030. [PMID: 30029459 PMCID: PMC6161107 DOI: 10.3390/proteomes6030030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 07/10/2018] [Accepted: 07/13/2018] [Indexed: 12/20/2022] Open
Abstract
The mammalian nervous system is an immensely heterogeneous organ composed of a diverse collection of neuronal types that interconnect in complex patterns. Synapses are highly specialized neuronal cell-cell junctions with common and distinct functional characteristics that are governed by their protein composition or synaptic proteomes. Even a single neuron can possess a wide-range of different synapse types and each synapse contains hundreds or even thousands of proteins. Many neurological disorders and diseases are caused by synaptic dysfunction within discrete neuronal populations. Mass spectrometry (MS)-based proteomic analysis has emerged as a powerful strategy to characterize synaptic proteomes and potentially identify disease driving synaptic alterations. However, most traditional synaptic proteomic analyses have been limited by molecular averaging of proteins from multiple types of neurons and synapses. Recently, several new strategies have emerged to tackle the ‘averaging problem’. In this review, we summarize recent advancements in our ability to characterize neuron-type specific and synapse-type specific proteomes and discuss strengths and limitations of these emerging analysis strategies.
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24
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An Essential Role for the Tetraspanin LHFPL4 in the Cell-Type-Specific Targeting and Clustering of Synaptic GABA A Receptors. Cell Rep 2018; 21:70-83. [PMID: 28978485 PMCID: PMC5640807 DOI: 10.1016/j.celrep.2017.09.025] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 07/17/2017] [Accepted: 09/06/2017] [Indexed: 02/04/2023] Open
Abstract
Inhibitory synaptic transmission requires the targeting and stabilization of GABAA receptors (GABAARs) at synapses. The mechanisms responsible remain poorly understood, and roles for transmembrane accessory proteins have not been established. Using molecular, imaging, and electrophysiological approaches, we identify the tetraspanin LHFPL4 as a critical regulator of postsynaptic GABAAR clustering in hippocampal pyramidal neurons. LHFPL4 interacts tightly with GABAAR subunits and is selectively enriched at inhibitory synapses. In LHFPL4 knockout mice, there is a dramatic cell-type-specific reduction in GABAAR and gephyrin clusters and an accumulation of large intracellular gephyrin aggregates in vivo. While GABAARs are still trafficked to the neuronal surface in pyramidal neurons, they are no longer localized at synapses, resulting in a profound loss of fast inhibitory postsynaptic currents. Hippocampal interneuron currents remain unaffected. Our results establish LHFPL4 as a synapse-specific tetraspanin essential for inhibitory synapse function and provide fresh insights into the molecular make-up of inhibitory synapses. LHFPL4 is a tetraspanin enriched at inhibitory synapses that complexes with GABAARs LHFPL4 is important for GABAAR clustering both in vitro and in vivo LHFPL4 is required for the surface clustering but not the trafficking of GABAARs GABAergic synaptic inputs on CA1 pyramidal neurons, but not interneurons, require LHFPL4
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25
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Wu M, Tian HL, Liu X, Lai JHC, Du S, Xia J. Impairment of Inhibitory Synapse Formation and Motor Behavior in Mice Lacking the NL2 Binding Partner LHFPL4/GARLH4. Cell Rep 2018; 23:1691-1705. [DOI: 10.1016/j.celrep.2018.04.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 02/26/2018] [Accepted: 04/02/2018] [Indexed: 12/25/2022] Open
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26
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Abstract
There are significant challenges in identifying receptor-specific functional interactors in vivo. In this issue of Neuron, Ge et al. (2018) identify a novel GABAA receptor (GABAAR)-interacting protein, Clptm1, that regulates forward trafficking of GABAARs and inhibitory transmission.
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Affiliation(s)
- Yoav Noam
- Department of Cellular and Molecular Physiology, Department of Neuroscience, CNNR program, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Department of Neuroscience, CNNR program, Yale University School of Medicine, New Haven, CT 06520, USA.
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27
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Mahadevan V, Khademullah CS, Dargaei Z, Chevrier J, Uvarov P, Kwan J, Bagshaw RD, Pawson T, Emili A, De Koninck Y, Anggono V, Airaksinen M, Woodin MA. Native KCC2 interactome reveals PACSIN1 as a critical regulator of synaptic inhibition. eLife 2017; 6:e28270. [PMID: 29028184 PMCID: PMC5640428 DOI: 10.7554/elife.28270] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 09/08/2017] [Indexed: 01/01/2023] Open
Abstract
KCC2 is a neuron-specific K+-Cl- cotransporter essential for establishing the Cl- gradient required for hyperpolarizing inhibition in the central nervous system (CNS). KCC2 is highly localized to excitatory synapses where it regulates spine morphogenesis and AMPA receptor confinement. Aberrant KCC2 function contributes to human neurological disorders including epilepsy and neuropathic pain. Using functional proteomics, we identified the KCC2-interactome in the mouse brain to determine KCC2-protein interactions that regulate KCC2 function. Our analysis revealed that KCC2 interacts with diverse proteins, and its most predominant interactors play important roles in postsynaptic receptor recycling. The most abundant KCC2 interactor is a neuronal endocytic regulatory protein termed PACSIN1 (SYNDAPIN1). We verified the PACSIN1-KCC2 interaction biochemically and demonstrated that shRNA knockdown of PACSIN1 in hippocampal neurons increases KCC2 expression and hyperpolarizes the reversal potential for Cl-. Overall, our global native-KCC2 interactome and subsequent characterization revealed PACSIN1 as a novel and potent negative regulator of KCC2.
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Affiliation(s)
- Vivek Mahadevan
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | | | - Zahra Dargaei
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Jonah Chevrier
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
| | - Pavel Uvarov
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Julian Kwan
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Richard D Bagshaw
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research InstituteMount Sinai HospitalTorontoCanada
| | - Andrew Emili
- Department of Molecular Genetics, Donnelly Centre for Cellular and Biomolecular ResearchUniversity of TorontoTorontoCanada
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de QuébecQuébecCanada
- Department of Psychiatry and NeuroscienceUniversité LavalQuébecCanada
| | - Victor Anggono
- Queensland Brain Institute, Clem Jones Centre for Ageing Dementia ResearchThe University of QueenslandBrisbaneAustralia
| | - Matti Airaksinen
- Department of Anatomy, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Melanie A Woodin
- Department of Cell and Systems BiologyUniversity of TorontoTorontoCanada
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28
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Bannai H. Molecular membrane dynamics: Insights into synaptic function and neuropathological disease. Neurosci Res 2017; 129:47-56. [PMID: 28826905 DOI: 10.1016/j.neures.2017.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/14/2017] [Accepted: 07/26/2017] [Indexed: 11/19/2022]
Abstract
The fluid mosaic model states that molecules in the plasma membrane can freely undergo lateral diffusion; however, in neurons and glia, specific membrane molecules are concentrated in cellular microdomains to overcome the randomizing effects of free diffusion. This specialized distribution of membrane molecules is crucial for various cell functions; one example is the accumulation of neurotransmitter receptors at the postsynaptic neuronal membrane, which enables efficient synaptic transmission. Quantum dot-single particle tracking (QD-SPT) is a super-resolution imaging technique that uses semiconductor nanocrystal quantum dots as fluorescent probes, and is a powerful tool for analyzing protein and lipid behavior in the plasma membrane. In this article, we review studies implementing QD-SPT in neuroscience research and important data gleaned using this technology. Recent QD-SPT experiments have provided critical insights into the mechanism and physiological relevance of membrane self-organization in neurons and astrocytes in the brain. The mobility of some membrane molecules may become abnormal in cellular models of epilepsy and Alzheimer's disease. Based on these findings, we propose that the behavior of membrane molecules reflects the condition of neurons in pathological disease states.
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Affiliation(s)
- Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
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29
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Krueger-Burg D, Papadopoulos T, Brose N. Organizers of inhibitory synapses come of age. Curr Opin Neurobiol 2017; 45:66-77. [DOI: 10.1016/j.conb.2017.04.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/05/2017] [Indexed: 12/14/2022]
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Baucum AJ. Proteomic Analysis of Postsynaptic Protein Complexes Underlying Neuronal Plasticity. ACS Chem Neurosci 2017; 8:689-701. [PMID: 28211672 DOI: 10.1021/acschemneuro.7b00008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Normal neuronal communication and synaptic plasticity at glutamatergic synapses requires dynamic regulation of postsynaptic molecules. Protein expression and protein post-translational modifications regulate protein interactions that underlie this organization. In this Review, we highlight data obtained over the last 20 years that have used qualitative and quantitative proteomics-based approaches to identify postsynaptic protein complexes. Herein, we describe how these proteomics studies have helped lay the foundation for understanding synaptic physiology and perturbations in synaptic signaling observed in different pathologies. We also describe emerging technologies that can be useful in these analyses. We focus on protein complexes associated with the highly abundant and functionally critical proteins: calcium/calmodulin-dependent protein kinase II, the N-methyl-d-aspartate, and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors, and postsynaptic density protein of 95 kDa.
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Affiliation(s)
- Anthony J. Baucum
- Department of Biology, Stark Neurosciences
Research Institute, Indiana University-Purdue University Indianapolis, 723 W. Michigan St., Indianapolis, Indiana 46202, United States
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31
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Uezu A, Kanak DJ, Bradshaw TWA, Soderblom EJ, Catavero CM, Burette AC, Weinberg RJ, Soderling SH. Identification of an elaborate complex mediating postsynaptic inhibition. Science 2017; 353:1123-9. [PMID: 27609886 DOI: 10.1126/science.aag0821] [Citation(s) in RCA: 223] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/25/2016] [Indexed: 12/13/2022]
Abstract
Inhibitory synapses dampen neuronal activity through postsynaptic hyperpolarization. The composition of the inhibitory postsynapse and the mechanistic basis of its regulation, however, remain poorly understood. We used an in vivo chemico-genetic proximity-labeling approach to discover inhibitory postsynaptic proteins. Quantitative mass spectrometry not only recapitulated known inhibitory postsynaptic proteins but also revealed a large network of new proteins, many of which are either implicated in neurodevelopmental disorders or are of unknown function. Clustered regularly interspaced short palindromic repeats (CRISPR) depletion of one of these previously uncharacterized proteins, InSyn1, led to decreased postsynaptic inhibitory sites, reduced the frequency of miniature inhibitory currents, and increased excitability in the hippocampus. Our findings uncover a rich and functionally diverse assemblage of previously unknown proteins that regulate postsynaptic inhibition and might contribute to developmental brain disorders.
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Affiliation(s)
- Akiyoshi Uezu
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Daniel J Kanak
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Tyler W A Bradshaw
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Erik J Soderblom
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. Duke Proteomics and Metabolomics Shared Resource and Duke Center for Genomic and Computational Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Christina M Catavero
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA
| | - Alain C Burette
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard J Weinberg
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, USA. Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Scott H Soderling
- The Department of Cell Biology, Duke University Medical School, Durham, NC 27703, USA. The Department of Neurobiology, Duke University Medical School, Durham, NC 27703, USA.
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Schreiner D, Savas JN, Herzog E, Brose N, de Wit J. Synapse biology in the 'circuit-age'-paths toward molecular connectomics. Curr Opin Neurobiol 2017; 42:102-110. [PMID: 28033531 PMCID: PMC5316339 DOI: 10.1016/j.conb.2016.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 11/23/2022]
Abstract
The neural connectome is a critical determinant of brain function. Circuits of precisely wired neurons, and the features of transmission at the synapses connecting them, are thought to dictate information processing in the brain. While recent technological advances now allow to define the anatomical and functional neural connectome at unprecedented resolution, the elucidation of the molecular mechanisms that establish the precise patterns of connectivity and the functional characteristics of synapses has remained challenging. Here, we describe the power and limitations of genetic approaches in the analysis of mechanisms that control synaptic connectivity and function, and discuss how recent methodological developments in proteomics might be used to elucidate the molecular synaptic connectome that is at the basis of the neural connectome.
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Affiliation(s)
- Dietmar Schreiner
- Biozentrum, University of Basel, Klingelbergstraße 50-70, 4056 Basel, Switzerland; Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover, Germany
| | - Jeffrey N Savas
- Department of Neurology, Northwestern University, Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
| | - Etienne Herzog
- Univ. Bordeaux, IINS, UMR 5297, F-33000 Bordeaux, France; CNRS, IINS, UMR 5297, F-33000 Bordeaux, France
| | - Nils Brose
- Department of Molecular Neurobiology, Max Planck Institute of Experimental Medicine, Hermann-Rein-Straße 3, 37075 Göttingen, Germany
| | - Joris de Wit
- VIB Center for Brain and Disease Research, Herestraat 49, 3000 Leuven, Belgium; Department of Neurosciences, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
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Loh KH, Stawski PS, Draycott AS, Udeshi ND, Lehrman EK, Wilton DK, Svinkina T, Deerinck TJ, Ellisman MH, Stevens B, Carr SA, Ting AY. Proteomic Analysis of Unbounded Cellular Compartments: Synaptic Clefts. Cell 2016; 166:1295-1307.e21. [PMID: 27565350 DOI: 10.1016/j.cell.2016.07.041] [Citation(s) in RCA: 247] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 05/16/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
Cellular compartments that cannot be biochemically isolated are challenging to characterize. Here we demonstrate the proteomic characterization of the synaptic clefts that exist at both excitatory and inhibitory synapses. Normal brain function relies on the careful balance of these opposing neural connections, and understanding how this balance is achieved relies on knowledge of their protein compositions. Using a spatially restricted enzymatic tagging strategy, we mapped the proteomes of two of the most common excitatory and inhibitory synaptic clefts in living neurons. These proteomes reveal dozens of synaptic candidates and assign numerous known synaptic proteins to a specific cleft type. The molecular differentiation of each cleft allowed us to identify Mdga2 as a potential specificity factor influencing Neuroligin-2's recruitment of presynaptic neurotransmitters at inhibitory synapses.
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Affiliation(s)
- Ken H Loh
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Philipp S Stawski
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | - Austin S Draycott
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA
| | | | - Emily K Lehrman
- F.M. Kirby Neurobiology Center, Boston Children's Hospital (BCH) and Harvard Medical School (HMS), Boston, MA 02115, USA
| | - Daniel K Wilton
- F.M. Kirby Neurobiology Center, Boston Children's Hospital (BCH) and Harvard Medical School (HMS), Boston, MA 02115, USA
| | - Tanya Svinkina
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Thomas J Deerinck
- National Center for Microscopy and Imaging Research, University of California at San Diego, La Jolla, CA 92093 USA; Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, University of California at San Diego, La Jolla, CA 92093 USA; Department of Neurosciences, University of California at San Diego, La Jolla, CA 92093, USA
| | - Beth Stevens
- F.M. Kirby Neurobiology Center, Boston Children's Hospital (BCH) and Harvard Medical School (HMS), Boston, MA 02115, USA
| | - Steven A Carr
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alice Y Ting
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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Nakamura Y, Morrow DH, Modgil A, Huyghe D, Deeb TZ, Lumb MJ, Davies PA, Moss SJ. Proteomic Characterization of Inhibitory Synapses Using a Novel pHluorin-tagged γ-Aminobutyric Acid Receptor, Type A (GABAA), α2 Subunit Knock-in Mouse. J Biol Chem 2016; 291:12394-407. [PMID: 27044742 DOI: 10.1074/jbc.m116.724443] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Indexed: 11/06/2022] Open
Abstract
The accumulation of γ-aminobutyric acid receptors (GABAARs) at the appropriate postsynaptic sites is critical for determining the efficacy of fast inhibitory neurotransmission. Although we know that the majority of synaptic GABAAR subtypes are assembled from α1-3, β, and γ2 subunits, our understanding of how neurons facilitate their targeting to and stabilization at inhibitory synapses is rudimentary. To address these issues, we have created knock-in mice in which the pH-sensitive green fluorescent protein (GFP) and the Myc epitope were introduced to the extracellular domain of the mature receptor α2 subunit (pHα2). Using immunoaffinity purification and mass spectroscopy, we identified a stable complex of 174 proteins that were associated with pHα2, including other GABAAR subunits, and previously identified receptor-associated proteins such as gephyrin and collybistin. 149 of these proteins were novel GABAAR binding partners and included G-protein-coupled receptors and ion channel subunits, proteins that regulate trafficking and degradation, regulators of protein phosphorylation, GTPases, and a number of proteins that regulate their activity. Notably, members of the postsynaptic density family of proteins that are critical components of excitatory synapses were not associated with GABAARs. Crucially, we demonstrated for a subset of these novel proteins (including cullin1, ephexin, potassium channel tetramerization domain containing protein 12, mitofusin2, metabotropic glutamate receptor 5, p21-activated kinase 7, and Ras-related protein 5A) bind directly to the intracellular domains of GABAARs, validating our proteomic analysis. Thus, our experiments illustrate the complexity of the GABAAR proteome and enhance our understanding of the mechanisms neurons use to construct inhibitory synapses.
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Affiliation(s)
- Yasuko Nakamura
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Danielle H Morrow
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Amit Modgil
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Deborah Huyghe
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Tarek Z Deeb
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Michael J Lumb
- the Department of Neuroscience, Physiology and Pharmacology, University College, London WC1E 6BT, United Kingdom
| | - Paul A Davies
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and
| | - Stephen J Moss
- From the Department of Neuroscience, Tufts University School of Medicine, Boston Massachusetts 02111 and the Department of Neuroscience, Physiology and Pharmacology, University College, London WC1E 6BT, United Kingdom
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35
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Li H, Aksenova M, Bertrand SJ, Mactutus CF, Booze R. Quantification of Filamentous Actin (F-actin) Puncta in Rat Cortical Neurons. J Vis Exp 2016:e53697. [PMID: 26889716 DOI: 10.3791/53697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Filamentous actin protein (F-actin) plays a major role in spinogenesis, synaptic plasticity, and synaptic stability. Changes in dendritic F-actin rich structures suggest alterations in synaptic integrity and connectivity. Here we provide a detailed protocol for culturing primary rat cortical neurons, Phalloidin staining for F-actin puncta, and subsequent quantification techniques. First, the frontal cortex of E18 rat embryos are dissociated into low-density cell culture, then the neurons grown in vitro for at least 12-14 days. Following experimental treatment, the cortical neurons are stained with AlexaFluor 488 Phalloidin (to label the dendritic F-actin puncta) and microtubule-associated protein 2 (MAP2; to validate the neuronal cells and dendritic integrity). Finally, specialized software is used to analyze and quantify randomly selected neuronal dendrites. F-actin rich structures are identified on second order dendritic branches (length range 25-75 µm) with continuous MAP2 immunofluorescence. The protocol presented here will be a useful method for investigating changes in dendritic synapse structures subsequent to experimental treatments.
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Affiliation(s)
- Hailong Li
- Laboratory Program in Behavioral, Neuroscience, Department of Psychology, University of South Carolina
| | - Marina Aksenova
- Laboratory Program in Behavioral, Neuroscience, Department of Psychology, University of South Carolina
| | - Sarah J Bertrand
- Laboratory Program in Behavioral, Neuroscience, Department of Psychology, University of South Carolina
| | - Charles F Mactutus
- Laboratory Program in Behavioral, Neuroscience, Department of Psychology, University of South Carolina
| | - Rosemarie Booze
- Laboratory Program in Behavioral, Neuroscience, Department of Psychology, University of South Carolina;
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36
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Ko J, Choii G, Um JW. The balancing act of GABAergic synapse organizers. Trends Mol Med 2016; 21:256-68. [PMID: 25824541 DOI: 10.1016/j.molmed.2015.01.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 01/25/2015] [Accepted: 01/27/2015] [Indexed: 12/14/2022]
Abstract
GABA (γ-aminobutyric acid) is the main neurotransmitter at inhibitory synapses in the mammalian brain. It is essential for maintaining the excitation and inhibition (E/I) ratio, whose imbalance underlies various brain diseases. Emerging information about inhibitory synapse organizers provides a novel molecular framework for understanding E/I balance at the synapse, circuit, and systems levels. This review highlights recent advances in deciphering these components of the inhibitory synapse and their roles in the development, transmission, and circuit properties of inhibitory synapses. We also discuss how their dysfunction may lead to a variety of brain disorders, suggesting new therapeutic strategies based on balancing the E/I ratio.
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37
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Bertrand SJ, Hu C, Aksenova MV, Mactutus CF, Booze RM. HIV-1 Tat and cocaine mediated synaptopathy in cortical and midbrain neurons is prevented by the isoflavone Equol. Front Microbiol 2015; 6:894. [PMID: 26441850 PMCID: PMC4561964 DOI: 10.3389/fmicb.2015.00894] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 08/17/2015] [Indexed: 02/05/2023] Open
Abstract
Illicit drugs, such as cocaine, are known to increase the likelihood and severity of HIV-1 associated neurocognitive disorders (HAND). In the current studies synaptic integrity was assessed following exposure to low concentrations of the HIV-1 viral protein Tat 1-86B, with or without cocaine, by quantifying filamentous actin (F-actin) rich structures (i.e., puncta and dendritic spines) on neuronal dendrites in vitro. In addition, the synapse-protective effects of either R-Equol (RE) or S-Equol (SE; derivatives of the soy isoflavone, daidzein) were determined. Individually, neither low concentrations of HIV-1 Tat (10 nM) nor low concentrations of cocaine (1.6 μM) had any significant effect on F-actin puncta number; however, the same low concentrations of HIV-1 Tat + cocaine in combination significantly reduced dendritic synapses. This synaptic reduction was prevented by pre-treatment with either RE or SE, in an estrogen receptor beta dependent manner. In sum, targeted therapeutic intervention with SE may prevent HIV-1 + drug abuse synaptopathy, and thereby potentially influence the development of HAND.
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Affiliation(s)
- Sarah J Bertrand
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina Columbia, SC, USA
| | - Calvin Hu
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina Columbia, SC, USA
| | - Marina V Aksenova
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina Columbia, SC, USA
| | - Charles F Mactutus
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina Columbia, SC, USA
| | - Rosemarie M Booze
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina Columbia, SC, USA
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38
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Pocklington AJ, Rees E, Walters JTR, Han J, Kavanagh DH, Chambert KD, Holmans P, Moran JL, McCarroll SA, Kirov G, O'Donovan MC, Owen MJ. Novel Findings from CNVs Implicate Inhibitory and Excitatory Signaling Complexes in Schizophrenia. Neuron 2015; 86:1203-14. [PMID: 26050040 PMCID: PMC4460187 DOI: 10.1016/j.neuron.2015.04.022] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 03/26/2015] [Accepted: 04/22/2015] [Indexed: 12/12/2022]
Abstract
We sought to obtain novel insights into schizophrenia pathogenesis by exploiting the association between the disorder and chromosomal copy number (CNV) burden. We combined data from 5,745 cases and 10,675 controls with other published datasets containing genome-wide CNV data. In this much-enlarged sample of 11,355 cases and 16,416 controls, we show for the first time that case CNVs are enriched for genes involved in GABAergic neurotransmission. Consistent with non-genetic reports of GABAergic deficits in schizophrenia, our findings now show disrupted GABAergic signaling is of direct causal relevance, rather than a secondary effect or due to confounding. Additionally, we independently replicate and greatly extend previous findings of CNV enrichment among genes involved in glutamatergic signaling. Given the strong functional links between the major inhibitory GABAergic and excitatory glutamatergic systems, our findings converge on a broad, coherent set of pathogenic processes, providing firm foundations for studies aimed at dissecting disease mechanisms.
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Affiliation(s)
- Andrew J Pocklington
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK.
| | - Elliott Rees
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - James T R Walters
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - Jun Han
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - David H Kavanagh
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - Kimberly D Chambert
- Stanley Center for Psychiatric Research, The Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Peter Holmans
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - Jennifer L Moran
- Stanley Center for Psychiatric Research, The Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA
| | - Steven A McCarroll
- Stanley Center for Psychiatric Research, The Broad Institute of MIT and Harvard, 75 Ames Street, Cambridge, MA 02142, USA; Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - George Kirov
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
| | - Michael C O'Donovan
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK.
| | - Michael J Owen
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF14 4XN, UK
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Pocklington AJ, O'Donovan M, Owen MJ. The synapse in schizophrenia. Eur J Neurosci 2014; 39:1059-67. [PMID: 24712986 DOI: 10.1111/ejn.12489] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 12/19/2013] [Accepted: 12/20/2013] [Indexed: 02/06/2023]
Abstract
It has been several decades since synaptic dysfunction was first suggested to play a role in schizophrenia, but only in the last few years has convincing evidence been obtained as progress has been made in elucidating the genetic underpinnings of the disorder. In the intervening years much has been learned concerning the complex macromolecular structure of the synapse itself, and genetic studies are now beginning to draw upon these advances. Here we outline our current understanding of the genetic architecture of schizophrenia and examine the evidence for synaptic involvement. A strong case can now be made that disruption of glutamatergic signalling pathways regulating synaptic plasticity contributes to the aetiology of schizophrenia.
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Affiliation(s)
- Andrew J Pocklington
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University School of Medicine, Hadyn Ellis Building, Maindy Road, Cathays, Cardiff, CF24 4HQ, UK
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40
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Kang Y, Ge Y, Cassidy RM, Lam V, Luo L, Moon KM, Lewis R, Molday RS, Wong ROL, Foster LJ, Craig AM. A combined transgenic proteomic analysis and regulated trafficking of neuroligin-2. J Biol Chem 2014; 289:29350-64. [PMID: 25190809 DOI: 10.1074/jbc.m114.549279] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Synapses, the basic units of communication in the brain, require complex molecular machinery for neurotransmitter release and reception. Whereas numerous components of excitatory postsynaptic sites have been identified, relatively few proteins are known that function at inhibitory postsynaptic sites. One such component is neuroligin-2 (NL2), an inhibitory synapse-specific cell surface protein that functions in cell adhesion and synaptic organization via binding to neurexins. In this study, we used a transgenic tandem affinity purification and mass spectrometry strategy to isolate and characterize NL2-associated complexes. Complexes purified from brains of transgenic His6-FLAG-YFP-NL2 mice showed enrichment in the Gene Ontology terms cell-cell signaling and synaptic transmission relative to complexes purified from wild type mice as a negative control. In addition to expected components including GABA receptor subunits and gephyrin, several novel proteins were isolated in association with NL2. Based on the presence of multiple components involved in trafficking and endocytosis, we showed that NL2 undergoes dynamin-dependent endocytosis in response to soluble ligand and colocalizes with VPS35 retromer in endosomes. Inhibitory synapses in brain also present a particular challenge for imaging. Whereas excitatory synapses on spines can be imaged with a fluorescent cell fill, inhibitory synapses require a molecular tag. We find the His6-FLAG-YFP-NL2 to be a suitable tag, with the unamplified YFP signal localizing appropriately to inhibitory synapses in multiple brain regions including cortex, hippocampus, thalamus, and basal ganglia. Altogether, we characterize NL2-associated complexes, demonstrate regulated trafficking of NL2, and provide tools for further proteomic and imaging studies of inhibitory synapses.
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Affiliation(s)
- Yunhee Kang
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada
| | - Yuan Ge
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada
| | - Robert M Cassidy
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada
| | - Vivian Lam
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada
| | - Lin Luo
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada
| | - Kyung-Mee Moon
- the Department of Biochemistry and Molecular Biology and Centre for High-throughput Biology and
| | - Renate Lewis
- the Department of Anatomy and Neurobiology, Washington University, St. Louis, Missouri 63110, and
| | - Robert S Molday
- the Department of Biochemistry and Molecular Biology and Centre for Macular Research, University of British Columbia, Vancouver V6T 1Z3, Canada
| | - Rachel O L Wong
- the Department of Biological Structure, University of Washington, Seattle, Washington 98195
| | - Leonard J Foster
- the Department of Biochemistry and Molecular Biology and Centre for High-throughput Biology and
| | - Ann Marie Craig
- From the Brain Research Centre and Department of Psychiatry, University of British Columbia, Vancouver V6T 2B5, Canada,
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41
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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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42
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Bertrand SJ, Mactutus CF, Aksenova MV, Espensen-Sturges TD, Booze RM. Synaptodendritic recovery following HIV Tat exposure: neurorestoration by phytoestrogens. J Neurochem 2013; 128:140-51. [PMID: 23875777 DOI: 10.1111/jnc.12375] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 06/22/2013] [Accepted: 07/03/2013] [Indexed: 12/17/2022]
Abstract
HIV-1 infects the brain and, despite antiretroviral therapy, many infected individuals suffer from HIV-1-associated neurocognitive disorders (HAND). HAND is associated with dendritic simplification and synaptic loss. Prevention of synaptodendritic damage may ameliorate or forestall neurocognitive decline in latent HIV-1 infections. The HIV-1 transactivating protein (Tat) is produced during viral latency in the brain and may cause synaptodendritic damage. This study examined the integrity of the dendritic network after exposure to HIV-1 Tat by labeling filamentous actin (F-actin)-rich structures (puncta) in primary neuronal cultures. After 24 h of treatment, HIV-1 Tat was associated with the dendritic arbor and produced a significant reduction of F-actin-labeled dendritic puncta as well as loss of dendrites. Pre-treatment with either of two plant-derived phytoestrogen compounds (daidzein and liquiritigenin), significantly reduced synaptodendritic damage following HIV-1 Tat treatment. In addition, 6 days after HIV-1 Tat treatment, treatment with either daidzein, or liquiritigenin enhanced recovery, via the estrogen receptor, from HIV-1 Tat-induced synaptodendritic damage. These results suggest that either liquiritigenin or daidzein may not only attenuate acute synaptodendritic injury in HIV-1 but may also promote recovery from synaptodendritic damage. The HIV-1 transactivating protein (Tat) is produced during viral latency in the brain. Treatment with either daidzein or liquiritigenin restored the loss of synaptic connectivity produced by HIV-1 Tat. This neurorestoration was mediated by estrogen receptors (ER). These results suggest that plant-derived phytoestrogens may promote recovery from HIV-1-induced synaptodendritic damage.
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Affiliation(s)
- Sarah J Bertrand
- Laboratory Program in Behavioral Neuroscience, Department of Psychology, University of South Carolina, Columbia, South Carolina, USA
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Craft GE, Chen A, Nairn AC. Recent advances in quantitative neuroproteomics. Methods 2013; 61:186-218. [PMID: 23623823 PMCID: PMC3891841 DOI: 10.1016/j.ymeth.2013.04.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Revised: 03/29/2013] [Accepted: 04/13/2013] [Indexed: 01/07/2023] Open
Abstract
The field of proteomics is undergoing rapid development in a number of different areas including improvements in mass spectrometric platforms, peptide identification algorithms and bioinformatics. In particular, new and/or improved approaches have established robust methods that not only allow for in-depth and accurate peptide and protein identification and modification, but also allow for sensitive measurement of relative or absolute quantitation. These methods are beginning to be applied to the area of neuroproteomics, but the central nervous system poses many specific challenges in terms of quantitative proteomics, given the large number of different neuronal cell types that are intermixed and that exhibit distinct patterns of gene and protein expression. This review highlights the recent advances that have been made in quantitative neuroproteomics, with a focus on work published over the last five years that applies emerging methods to normal brain function as well as to various neuropsychiatric disorders including schizophrenia and drug addiction as well as of neurodegenerative diseases including Parkinson's disease and Alzheimer's disease. While older methods such as two-dimensional polyacrylamide electrophoresis continued to be used, a variety of more in-depth MS-based approaches including both label (ICAT, iTRAQ, TMT, SILAC, SILAM), label-free (label-free, MRM, SWATH) and absolute quantification methods, are rapidly being applied to neurobiological investigations of normal and diseased brain tissue as well as of cerebrospinal fluid (CSF). While the biological implications of many of these studies remain to be clearly established, that there is a clear need for standardization of experimental design and data analysis, and that the analysis of protein changes in specific neuronal cell types in the central nervous system remains a serious challenge, it appears that the quality and depth of the more recent quantitative proteomics studies is beginning to shed light on a number of aspects of neuroscience that relates to normal brain function as well as of the changes in protein expression and regulation that occurs in neuropsychiatric and neurodegenerative disorders.
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Affiliation(s)
- George E Craft
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
| | - Anshu Chen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
- Yale/NIDA Neuroproteomics Center, Yale University School of Medicine, New Haven, CT, 06508
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Zhou C, Huang Z, Ding L, Deel ME, Arain FM, Murray CR, Patel RS, Flanagan CD, Gallagher MJ. Altered cortical GABAA receptor composition, physiology, and endocytosis in a mouse model of a human genetic absence epilepsy syndrome. J Biol Chem 2013; 288:21458-21472. [PMID: 23744069 DOI: 10.1074/jbc.m112.444372] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Patients with generalized epilepsy exhibit cerebral cortical disinhibition. Likewise, mutations in the inhibitory ligand-gated ion channels, GABAA receptors (GABAARs), cause generalized epilepsy syndromes in humans. Recently, we demonstrated that heterozygous knock-out (Hetα1KO) of the human epilepsy gene, the GABAAR α1 subunit, produced absence epilepsy in mice. Here, we determined the effects of Hetα1KO on the expression and physiology of GABAARs in the mouse cortex. We found that Hetα1KO caused modest reductions in the total and surface expression of the β2 subunit but did not alter β1 or β3 subunit expression, results consistent with a small reduction of GABAARs. Cortices partially compensated for Hetα1KO by increasing the fraction of residual α1 subunit on the cell surface and by increasing total and surface expression of α3, but not α2, subunits. Co-immunoprecipitation experiments revealed that Hetα1KO increased the fraction of α1 subunits, and decreased the fraction of α3 subunits, that associated in hybrid α1α3βγ receptors. Patch clamp electrophysiology studies showed that Hetα1KO layer VI cortical neurons exhibited reduced inhibitory postsynaptic current peak amplitudes, prolonged current rise and decay times, and altered responses to benzodiazepine agonists. Finally, application of inhibitors of dynamin-mediated endocytosis revealed that Hetα1KO reduced base-line GABAAR endocytosis, an effect that probably contributes to the observed changes in GABAAR expression. These findings demonstrate that Hetα1KO exerts two principle disinhibitory effects on cortical GABAAR-mediated inhibitory neurotransmission: 1) a modest reduction of GABAAR number and 2) a partial compensation with GABAAR isoforms that possess physiological properties different from those of the otherwise predominant α1βγ GABAARs.
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Affiliation(s)
- Chengwen Zhou
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - Zhiling Huang
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - Li Ding
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - M Elizabeth Deel
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - Fazal M Arain
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - Clark R Murray
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | - Ronak S Patel
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232
| | | | - Martin J Gallagher
- From the Department of Neurology, Vanderbilt University, Nashville, Tennessee 37232.
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Abstract
The concept of a tripartite synapse including a presynaptic terminal, a postsynaptic spine, and an astrocytic process that responds to neuronal activity by fast gliotransmitter release, confers to the electrically silent astrocytes an active role in information processing. However, the mechanisms of gliotransmitter release are still highly controversial. The reported expression of all three vesicular glutamate transporters (VGLUT1-3) by astrocytes suggests that astrocytes, like neurons, may release glutamate by exocytosis. However, the demonstration of astrocytic VGLUT expression is largely based on immunostaining, and the possibility of nonspecific labeling needs to be systematically addressed. We therefore examined the expression of VGLUT1-3 in astrocytes, both in culture and in situ. We used Western blots and single-vesicle imaging by total internal reflection fluorescence microscopy in live cultured astrocytes, and confocal microscopy, at the cellular level in cortical, hippocampal, and cerebellar brain slices, combined with quantitative image analysis. Control experiments were systematically performed in cultured astrocytes using wild-type, VGLUT1-3 knock-out, VGLUT1(Venus) knock-in, and VGLUT2-EGFP transgenic mice. In fixed brain slices, we quantified the degree of overlap between VGLUT1-3 and neuronal or astrocytic markers, both in an object-based manner using fluorescence line profiles, and in a pixel-based manner using dual-color scatter plots followed by the calculation of Pearson's correlation coefficient over all pixels with intensities significantly different from background. Our data provide no evidence in favor of the expression of any of the three VGLUTs by gray matter protoplasmic astrocytes of the primary somatosensory cortex, the thalamic ventrobasal nucleus, the hippocampus, and the cerebellum.
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Miteva YV, Budayeva HG, Cristea IM. Proteomics-based methods for discovery, quantification, and validation of protein-protein interactions. Anal Chem 2013; 85:749-68. [PMID: 23157382 PMCID: PMC3666915 DOI: 10.1021/ac3033257] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - Ileana M. Cristea
- Corresponding author: Ileana M. Cristea 210 Lewis Thomas Laboratory Department of Molecular Biology Princeton University Princeton, NJ 08544 Tel: 6092589417 Fax: 6092584575
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