1
|
Lee H, Kang H, Moon C, Youn B. PAK3 downregulation induces cognitive impairment following cranial irradiation. eLife 2023; 12:RP89221. [PMID: 38131292 PMCID: PMC10746143 DOI: 10.7554/elife.89221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023] Open
Abstract
Cranial irradiation is used for prophylactic brain radiotherapy as well as the treatment of primary brain tumors. Despite its high efficiency, it often induces unexpected side effects, including cognitive dysfunction. Herein, we observed that mice exposed to cranial irradiation exhibited cognitive dysfunction, including altered spontaneous behavior, decreased spatial memory, and reduced novel object recognition. Analysis of the actin cytoskeleton revealed that ionizing radiation (IR) disrupted the filamentous/globular actin (F/G-actin) ratio and downregulated the actin turnover signaling pathway p21-activated kinase 3 (PAK3)-LIM kinase 1 (LIMK1)-cofilin. Furthermore, we found that IR could upregulate microRNA-206-3 p (miR-206-3 p) targeting PAK3. As the inhibition of miR-206-3 p through antagonist (antagomiR), IR-induced disruption of PAK3 signaling is restored. In addition, intranasal administration of antagomiR-206-3 p recovered IR-induced cognitive impairment in mice. Our results suggest that cranial irradiation-induced cognitive impairment could be ameliorated by regulating PAK3 through antagomiR-206-3 p, thereby affording a promising strategy for protecting cognitive function during cranial irradiation, and promoting quality of life in patients with radiation therapy.
Collapse
Affiliation(s)
- Haksoo Lee
- Department of Integrated Biological Science, Pusan National UniversityBusanRepublic of Korea
| | - Hyunkoo Kang
- Department of Integrated Biological Science, Pusan National UniversityBusanRepublic of Korea
| | - Changjong Moon
- Department of Veterinary Anatomy and Animal Behavior, College of Veterinary Medicine and BK21 FOUR Program, Chonnam National UniversityGwangjuRepublic of Korea
| | - BuHyun Youn
- Department of Integrated Biological Science, Pusan National UniversityBusanRepublic of Korea
- Department of Biological Sciences, Pusan National UniversityBusanRepublic of Korea
- Nuclear Science Research Institute, Pusan National UniversityBusanRepublic of Korea
| |
Collapse
|
2
|
Garcia JD, Wolfe SE, Stewart AR, Tiemeier E, Gookin SE, Guerrero MB, Quillinan N, Smith KR. Distinct mechanisms drive sequential internalization and degradation of GABA ARs during global ischemia and reperfusion injury. iScience 2023; 26:108061. [PMID: 37860758 PMCID: PMC10582478 DOI: 10.1016/j.isci.2023.108061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/30/2023] [Accepted: 09/22/2023] [Indexed: 10/21/2023] Open
Abstract
Synaptic inhibition is critical for controlling neuronal excitability and function. During global cerebral ischemia (GCI), inhibitory synapses are rapidly eliminated, causing hyper-excitability which contributes to cell-death and the pathophysiology of disease. Sequential disassembly of inhibitory synapses begins within minutes of ischemia onset: GABAARs are rapidly trafficked away from the synapse, the gephyrin scaffold is removed, followed by loss of the presynaptic terminal. GABAARs are endocytosed during GCI, but how this process accompanies synapse disassembly remains unclear. Here, we define the precise trafficking itinerary of GABAARs during the initial stages of GCI, placing them in the context of rapid synapse elimination. Ischemia-induced GABAAR internalization quickly follows their initial dispersal from the synapse, and is controlled by PP1α signaling. During reperfusion injury, GABAARs are then trafficked to lysosomes for degradation, leading to permanent removal of synaptic GABAARs and contributing to the profound reduction in synaptic inhibition observed hours following ischemia onset.
Collapse
Affiliation(s)
- Joshua D. Garcia
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Sarah E. Wolfe
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Amber R. Stewart
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Erika Tiemeier
- Department of Anesthesiology, Neuronal Injury Program, University of Colorado School of Medicine, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Sara E. Gookin
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Mayra Bueno Guerrero
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Nidia Quillinan
- Department of Anesthesiology, Neuronal Injury Program, University of Colorado School of Medicine, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Katharine R. Smith
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| |
Collapse
|
3
|
Thompson M, Gordon MG, Lu A, Tandon A, Halperin E, Gusev A, Ye CJ, Balliu B, Zaitlen N. Multi-context genetic modeling of transcriptional regulation resolves novel disease loci. Nat Commun 2022; 13:5704. [PMID: 36171194 PMCID: PMC9519579 DOI: 10.1038/s41467-022-33212-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 09/07/2022] [Indexed: 12/01/2022] Open
Abstract
A majority of the variants identified in genome-wide association studies fall in non-coding regions of the genome, indicating their mechanism of impact is mediated via gene expression. Leveraging this hypothesis, transcriptome-wide association studies (TWAS) have assisted in both the interpretation and discovery of additional genes associated with complex traits. However, existing methods for conducting TWAS do not take full advantage of the intra-individual correlation inherently present in multi-context expression studies and do not properly adjust for multiple testing across contexts. We introduce CONTENT-a computationally efficient method with proper cross-context false discovery correction that leverages correlation structure across contexts to improve power and generate context-specific and context-shared components of expression. We apply CONTENT to bulk multi-tissue and single-cell RNA-seq data sets and show that CONTENT leads to a 42% (bulk) and 110% (single cell) increase in the number of genetically predicted genes relative to previous approaches. We find the context-specific component of expression comprises 30% of heritability in tissue-level bulk data and 75% in single-cell data, consistent with cell-type heterogeneity in bulk tissue. In the context of TWAS, CONTENT increases the number of locus-phenotype associations discovered by over 51% relative to previous methods across 22 complex traits.
Collapse
Affiliation(s)
- Mike Thompson
- Department of Computer Science, University of California Los Angeles, Los Angeles, CA, USA.
| | - Mary Grace Gordon
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA
- Biological and Medical Informatics Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Andrew Lu
- UCLA-Caltech Medical Scientist Training Program, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Anchit Tandon
- Department of Mathematics, Indian Institute of Technology Delhi, Hauz Khas, Delhi, India
| | - Eran Halperin
- Department of Computer Science, University of California Los Angeles, Los Angeles, CA, USA
- Department of Human Genetics, University of California Los Angeles, Los Angeles, CA, USA
- Department of Anesthesiology and Perioperative Medicine, University of California Los Angeles, Los Angeles, CA, USA
- Department of Computational Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Alexander Gusev
- Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, US
- Division of Genetics, Brigham and Women's Hospital, Boston, MA, US
| | - Chun Jimmie Ye
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA
- Chan-Zuckerberg Biohub, San Francisco, CA, USA
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
- Institute for Computational Health Sciences, University of California, San Francisco, San Francisco, CA, USA
| | - Brunilda Balliu
- Department of Computational Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Noah Zaitlen
- Department of Computer Science, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA.
| |
Collapse
|
4
|
Halff EF, Hannan S, Kwanthongdee J, Lesept F, Smart TG, Kittler JT. Phosphorylation of neuroligin-2 by PKA regulates its cell surface abundance and synaptic stabilization. Sci Signal 2022; 15:eabg2505. [PMID: 35727864 DOI: 10.1126/scisignal.abg2505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The trans-synaptic adhesion molecule neuroligin-2 (NL2) is essential for the development and function of inhibitory synapses. NL2 recruits the postsynaptic scaffold protein gephyrin, which, in turn, stabilizes γ-aminobutyric acid type A receptors (GABAARs) in the postsynaptic domain. Thus, the amount of NL2 at the synapse can control synaptic GABAAR concentration to tune inhibitory neurotransmission efficacy. Here, using biochemistry, imaging, single-particle tracking, and electrophysiology, we uncovered a key role for cAMP-dependent protein kinase (PKA) in the synaptic stabilization of NL2. We found that PKA-mediated phosphorylation of NL2 at Ser714 caused its dispersal from the synapse and reduced NL2 surface amounts, leading to a loss of synaptic GABAARs. Conversely, enhancing the stability of NL2 at synapses by abolishing PKA-mediated phosphorylation led to increased inhibitory signaling. Thus, PKA plays a key role in regulating NL2 function and GABA-mediated synaptic inhibition.
Collapse
Affiliation(s)
- Els F Halff
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - Saad Hannan
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - Jaturon Kwanthongdee
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK.,Princess Srisavangavadhana College of Medicine, Chulabhorn Royal Academy, Bangkok 10210, Thailand
| | - Flavie Lesept
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - Trevor G Smart
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology, and Pharmacology, University College London, London WC1E 6BT, UK
| |
Collapse
|
5
|
Garcia JD, Gookin SE, Crosby KC, Schwartz SL, Tiemeier E, Kennedy MJ, Dell'Acqua ML, Herson PS, Quillinan N, Smith KR. Stepwise disassembly of GABAergic synapses during pathogenic excitotoxicity. Cell Rep 2021; 37:110142. [PMID: 34936876 PMCID: PMC8824488 DOI: 10.1016/j.celrep.2021.110142] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 09/17/2021] [Accepted: 11/23/2021] [Indexed: 12/16/2022] Open
Abstract
GABAergic synaptic inhibition controls neuronal firing, excitability, and synaptic plasticity to regulate neuronal circuits. Following an acute excitotoxic insult, inhibitory synapses are eliminated, reducing synaptic inhibition, elevating circuit excitability, and contributing to the pathophysiology of brain injuries. However, mechanisms that drive inhibitory synapse disassembly and elimination are undefined. We find that inhibitory synapses are disassembled in a sequential manner following excitotoxicity: GABAARs undergo rapid nanoscale rearrangement and are dispersed from the synapse along with presynaptic active zone components, followed by the gradual removal of the gephyrin scaffold, prior to complete elimination of the presynaptic terminal. GABAAR nanoscale reorganization and synaptic declustering depends on calcineurin signaling, whereas disassembly of gephyrin relies on calpain activation, and blockade of both enzymes preserves inhibitory synapses after excitotoxic insult. Thus, inhibitory synapse disassembly occurs rapidly, with nanoscale precision, in a stepwise manner and most likely represents a critical step in the progression of hyperexcitability following excitotoxicity.
Collapse
Affiliation(s)
- Joshua D Garcia
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Sara E Gookin
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Kevin C Crosby
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Samantha L Schwartz
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Erika Tiemeier
- Department of Anesthesiology, Neuronal Injury Program, University of Colorado School of Medicine, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Matthew J Kennedy
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA
| | - Paco S Herson
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA; Department of Anesthesiology, Neuronal Injury Program, University of Colorado School of Medicine, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Nidia Quillinan
- Department of Anesthesiology, Neuronal Injury Program, University of Colorado School of Medicine, Anschutz Medical Campus, 12801 East 17th Avenue, Aurora, CO 80045, USA
| | - Katharine R Smith
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, 12800 East 19th Avenue, Aurora, CO 80045, USA.
| |
Collapse
|
6
|
Sahin GS, Luis Rodriguez-Llamas J, Dillon C, Medina I, Appleyard SM, Gaiarsa JL, Wayman GA. Leptin increases GABAergic synaptogenesis through the Rho guanine exchange factor β-PIX in developing hippocampal neurons. Sci Signal 2021; 14:14/683/eabe4111. [PMID: 34006608 DOI: 10.1126/scisignal.abe4111] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Developing hippocampal neurons undergo rapid synaptogenesis in response to neurotrophic signals to form and refine circuit connections. The adipokine leptin is a satiety factor with neurotrophic actions, which potentiates both glutamatergic and GABAergic synaptogenesis in the hippocampus during neonatal development. Brief exposure to leptin enhances GABAA receptor-dependent synaptic currents in hippocampal neurons. Here, using molecular and electrophysiological techniques, we found that leptin increased the surface localization of GABAA receptors and the number of functional GABAergic synapses in hippocampal cultures from male and female rat pups. Leptin increased the interaction between GABAA receptors and the Rho guanine exchange factor β-PIX (a scaffolding protein at GABAergic postsynaptic sites) in a manner dependent on the kinase CaMKK. We also found that the leptin receptor and β-PIX formed a complex, the amount of which transiently increased upon leptin receptor activation. Furthermore, Tyr985 in the leptin receptor and the SH3 domain of β-PIX are crucial for this interaction, which was required for the developmental increase in GABAergic synaptogenesis. Our results suggest a mechanism by which leptin promotes GABAergic synaptogenesis in hippocampal neurons and reveal further complexity in leptin receptor signaling and its interactome.
Collapse
Affiliation(s)
- Gulcan Semra Sahin
- Department of Integrated Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Jose Luis Rodriguez-Llamas
- Department of Integrated Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Crystal Dillon
- Department of Integrated Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Igor Medina
- Aix-Marseille University UMR 1249, INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, INMED (Institut de Neurobiologie de la Méditerranée), Marseille, France
| | - Suzanne M Appleyard
- Department of Integrated Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA
| | - Jean-Luc Gaiarsa
- Aix-Marseille University UMR 1249, INSERM (Institut National de la Santé et de la Recherche Médicale) Unité 1249, INMED (Institut de Neurobiologie de la Méditerranée), Marseille, France
| | - Gary A Wayman
- Department of Integrated Physiology and Neuroscience, Washington State University, Pullman, WA 99164 USA.
| |
Collapse
|
7
|
Local miRNA-Dependent Translational Control of GABA AR Synthesis during Inhibitory Long-Term Potentiation. Cell Rep 2021; 31:107785. [PMID: 32579917 PMCID: PMC7486624 DOI: 10.1016/j.celrep.2020.107785] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 04/14/2020] [Accepted: 05/28/2020] [Indexed: 12/29/2022] Open
Abstract
Molecular mechanisms underlying plasticity at brain inhibitory synapses remain poorly characterized. Increased postsynaptic clustering of GABAA receptors (GABAARs) rapidly strengthens inhibition during inhibitory long-term potentiation (iLTP). However, it is unclear how synaptic GABAAR clustering is maintained to sustain iLTP. Here, we identify a role for miR376c in regulating the translation of mRNAs encoding the synaptic α1 and γ2 GABAAR subunits, GABRA1 and GABRG2, respectively. Following iLTP induction, transcriptional repression of miR376c is induced through a calcineurin-NFAT-HDAC signaling pathway and promotes increased translation and clustering of synaptic GABAARs. This pathway is essential for the long-term expression of iLTP and is blocked by miR376c overexpression, specifically impairing inhibitory synaptic strength. Finally, we show that local de novo synthesis of synaptic GABAARs occurs exclusively in dendrites and in a miR376c-dependent manner following iLTP. Together, this work describes a local post-transcriptional mechanism that regulates inhibitory synaptic plasticity via miRNA control of dendritic protein synthesis. Clustering of GABAARs at inhibitory synapses is crucial for synaptic inhibition. Rajgor et al. discover that synaptic GABAAR expression is controlled by their local translation, regulated by miR376c. During inhibitory synaptic potentiation, miR376c is downregulated, relieving its translational repression of GABAAR mRNAs and leading to de novo synthesis of dendritic GABAARs.
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Zhang K, Wang Y, Fan T, Zeng C, Sun ZS. The p21-activated kinases in neural cytoskeletal remodeling and related neurological disorders. Protein Cell 2020; 13:6-25. [PMID: 33306168 PMCID: PMC8776968 DOI: 10.1007/s13238-020-00812-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 11/19/2020] [Indexed: 12/15/2022] Open
Abstract
The serine/threonine p21-activated kinases (PAKs), as main effectors of the Rho GTPases Cdc42 and Rac, represent a group of important molecular switches linking the complex cytoskeletal networks to broad neural activity. PAKs show wide expression in the brain, but they differ in specific cell types, brain regions, and developmental stages. PAKs play an essential and differential role in controlling neural cytoskeletal remodeling and are related to the development and fate of neurons as well as the structural and functional plasticity of dendritic spines. PAK-mediated actin signaling and interacting functional networks represent a common pathway frequently affected in multiple neurodevelopmental and neurodegenerative disorders. Considering specific small-molecule agonists and inhibitors for PAKs have been developed in cancer treatment, comprehensive knowledge about the role of PAKs in neural cytoskeletal remodeling will promote our understanding of the complex mechanisms underlying neurological diseases, which may also represent potential therapeutic targets of these diseases.
Collapse
Affiliation(s)
- Kaifan Zhang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.,Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, 325000, China
| | - Yan Wang
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Tianda Fan
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, 325000, China
| | - Cheng Zeng
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China.,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhong Sheng Sun
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101, China. .,Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, 325000, China. .,CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China. .,State Key Laboratory of Integrated Management of Pest Insects and Rodents, Chinese Academy of Sciences, Beijing, 100101, China.
| |
Collapse
|
10
|
SNX27-Mediated Recycling of Neuroligin-2 Regulates Inhibitory Signaling. Cell Rep 2020; 29:2599-2607.e6. [PMID: 31775031 PMCID: PMC6899438 DOI: 10.1016/j.celrep.2019.10.096] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/22/2019] [Accepted: 10/24/2019] [Indexed: 01/11/2023] Open
Abstract
GABAA receptors mediate fast inhibitory transmission in the brain, and their number can be rapidly up- or downregulated to alter synaptic strength. Neuroligin-2 plays a critical role in the stabilization of synaptic GABAA receptors and the development and maintenance of inhibitory synapses. To date, little is known about how the amount of neuroligin-2 at the synapse is regulated and whether neuroligin-2 trafficking affects inhibitory signaling. Here, we show that neuroligin-2, when internalized to endosomes, co-localizes with SNX27, a brain-enriched cargo-adaptor protein that facilitates membrane protein recycling. Direct interaction between the PDZ domain of SNX27 and PDZ-binding motif in neuroligin-2 enables membrane retrieval of neuroligin-2, thus enhancing synaptic neuroligin-2 clusters. Furthermore, SNX27 knockdown has the opposite effect. SNX27-mediated up- and downregulation of neuroligin-2 surface levels affects inhibitory synapse composition and signaling strength. Taken together, we show a role for SNX27-mediated recycling of neuroligin-2 in maintenance and signaling of the GABAergic synapse.
Collapse
|
11
|
Developmental Phase Transitions in Spatial Organization of Spontaneous Activity in Postnatal Barrel Cortex Layer 4. J Neurosci 2020; 40:7637-7650. [PMID: 32887743 DOI: 10.1523/jneurosci.1116-20.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 07/27/2020] [Accepted: 08/16/2020] [Indexed: 12/16/2022] Open
Abstract
Spatially-organized spontaneous activity is a characteristic feature of developing mammalian sensory systems. However, the transitions of spontaneous-activity spatial organization during development and related mechanisms remain largely unknown. We reported previously that layer 4 (L4) glutamatergic neurons in the mouse barrel cortex exhibit spontaneous activity with a patchwork-type pattern at postnatal day (P)5, which is during barrel formation. In the current work, we revealed that spontaneous activity in mouse barrel-cortex L4 glutamatergic neurons exhibits at least three phases during the first two weeks of postnatal development. Phase I activity has a patchwork-type pattern and is observed not only at P5, but also P1, before barrel formation. Phase II is found at P9, by which time barrel formation is completed, and exhibits broadly synchronized activity across barrel borders. Phase III emerges around P11 when L4-neuron activity is desynchronized. The Phase I activity, but not Phase II or III activity, is blocked by thalamic inhibition, demonstrating that the Phase I to II transition is associated with loss of thalamic dependency. Dominant-negative (DN)-Rac1 expression in L4 neurons hampers the Phase II to III transition. It also suppresses developmental increases in spine density and excitatory synapses of L4 neurons in the second postnatal week, suggesting that Rac1-mediated synapse maturation could underlie the Phase II to III transition. Our findings revealed the presence of distinct mechanisms for Phase I to II and Phase II to III transition. They also highlighted the role of a small GTPase in the developmental desynchronization of cortical spontaneous activity.SIGNIFICANCE STATEMENT Developing neocortex exhibits spatially-organized spontaneous activity, which plays a critical role in cortical circuit development. The features of spontaneous-activity spatial organization and the mechanisms underlying its changes during development remain largely unknown. In the present study, using two-photon in vivo imaging, we revealed three phases (Phases I, II, and III) of spontaneous activity in barrel-cortex layer 4 (L4) glutamatergic neurons during the first two postnatal weeks. We also demonstrated the presence of distinct mechanisms underlying phase transitions. Phase I to II shift arose from the switch in the L4-neuron driving source, and Phase II to III transition relied on L4-neuron Rac1 activity. These results provide new insights into the principles of developmental transitions of neocortical spontaneous-activity spatial patterns.
Collapse
|
12
|
Genome-wide DNA methylation alteration in prenatally stressed Brahman heifer calves with the advancement of age. Epigenetics 2020; 16:519-536. [PMID: 32815760 DOI: 10.1080/15592294.2020.1805694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Possible phenotypic impairments associated with maternal stress during gestation in beef cattle may be explained by epigenetic effects. This study examined the impact of prenatal transportation stress on DNA methylation of lymphocytes of Brahman cows over the first 5 years of life. Methylation analysis through reduced representation bisulphite sequencing was conducted on DNA from lymphocytes from 28 paired samples from 6 prenatally stressed (PNS) and 8 control (Control) females obtained initially when they were 28 days of age and 5 years of age. There were 14,386 CpG (C = cytosine; p = phosphate; G = guanine) sites differentially methylated (P < 0.01) in 5-yr-old Control cows compared to their lymphocyte DNA at 28 days of age, this number was slightly decreased in 5-yr-old PNS with 13,378 CpG sites. Only 2,749 age-related differentially methylated CpG sites were seen within PNS females. There were 2,637 CpG sites differentially methylated (P < 0.01) in PNS cows relative to Controls at 5 years of age. There were differentially methylated genes in 5-yr-old cows that contributed similarly to altered gene pathways in both treatment groups. Canonical pathways altered in PNS compared to Control cows at 5 years of age were mostly related to development and growth, nervous system development and function, and immune response. Prenatal stress appeared to alter the epigenome in Brahman cows compared to Control at 5 years of age, which implies a persistent intervention in DNA methylation in lymphocytes, and may confer long-lasting effects on gene expression, and consequently relevant phenotypic changes.
Collapse
|
13
|
Pizzarelli R, Griguoli M, Zacchi P, Petrini EM, Barberis A, Cattaneo A, Cherubini E. Tuning GABAergic Inhibition: Gephyrin Molecular Organization and Functions. Neuroscience 2020; 439:125-136. [PMID: 31356900 PMCID: PMC7351109 DOI: 10.1016/j.neuroscience.2019.07.036] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 01/15/2023]
Abstract
To be highly reliable, synaptic transmission needs postsynaptic receptors (Rs) in precise apposition to the presynaptic release sites. At inhibitory synapses, the postsynaptic protein gephyrin self-assembles to form a scaffold that anchors glycine and GABAARs to the cytoskeleton, thus ensuring the accurate accumulation of postsynaptic receptors at the right place. This protein undergoes several post-translational modifications which control protein-protein interaction and downstream signaling pathways. In addition, through the constant exchange of scaffolding elements and receptors in and out of synapses, gephyrin dynamically regulates synaptic strength and plasticity. The aim of the present review is to highlight recent findings on the functional role of gephyrin at GABAergic inhibitory synapses. We will discuss different approaches used to interfere with gephyrin in order to unveil its function. In addition, we will focus on the impact of gephyrin structure and distribution at the nanoscale level on the functional properties of inhibitory synapses as well as the implications of this scaffold protein in synaptic plasticity processes. Finally, we will emphasize how gephyrin genetic mutations or alterations in protein expression levels are implicated in several neuropathological disorders, including autism spectrum disorders, schizophrenia, temporal lobe epilepsy and Alzheimer's disease, all associated with severe deficits of GABAergic signaling. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
Collapse
Affiliation(s)
- Rocco Pizzarelli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Marilena Griguoli
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy
| | - Paola Zacchi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Enrica Maria Petrini
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Andrea Barberis
- Fondazione Istituto Italiano di Tecnologia (IIT), Department of Neuroscience and Brain Technologies, Plasticity of inhibitory networks Unit, Genoa, Italy
| | - Antonino Cattaneo
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Normale Superiore, Pisa, Italy
| | - Enrico Cherubini
- European Brain Research Institute (EBRI), Fondazione Rita Levi-Montalcini, Roma, Italy; Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy.
| |
Collapse
|
14
|
Norkett R, Lesept F, Kittler JT. DISC1 Regulates Mitochondrial Trafficking in a Miro1-GTP-Dependent Manner. Front Cell Dev Biol 2020; 8:449. [PMID: 32637409 PMCID: PMC7317294 DOI: 10.3389/fcell.2020.00449] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/13/2020] [Indexed: 11/20/2022] Open
Abstract
The disrupted in schizophrenia 1 (DISC1) protein is implicated in major mental illnesses including schizophrenia and bipolar disorder. A key feature of psychiatric disease is aberrant synaptic communication. Correct synaptic transmission is dependent on spatiotemporally regulated energy provision and calcium buffering. This can be achieved by precise distribution of mitochondria throughout the elaborate architecture of the neuron. Central to this process is the calcium sensor and GTPase Miro1, which allows mitochondrial trafficking by molecular motors. While the role of Miro1-calcium binding in mitochondrial transport is well described, far less is known regarding the functions of the two GTPase domains. Here, we investigate the effects of a psychiatric disease-associated mutation in DISC1 on mitochondrial trafficking. We show that this DISC1 mutation impairs Miro1’s ability to transport mitochondria. We also demonstrate the necessity of the first Miro1 GTPase domain in determining direction of mitochondrial transport and the involvement of DISC1 in this process. Finally, we describe the effects of mutant DISC1 on positioning of mitochondria at synapses.
Collapse
Affiliation(s)
- Rosalind Norkett
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Flavie Lesept
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| |
Collapse
|
15
|
Bannai H, Niwa F, Sakuragi S, Mikoshiba K. Inhibitory synaptic transmission tuned by Ca 2+ and glutamate through the control of GABA A R lateral diffusion dynamics. Dev Growth Differ 2020; 62:398-406. [PMID: 32329058 PMCID: PMC7496684 DOI: 10.1111/dgd.12667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/08/2020] [Accepted: 04/18/2020] [Indexed: 11/30/2022]
Abstract
The GABAergic synapses, a primary inhibitory synapse in the mammalian brain, is important for the normal development of brain circuits, and for the regulation of the excitation‐inhibition balance critical for brain function from the developmental stage throughout life. However, the molecular mechanism underlying the formation, maintenance, and modulation of GABAergic synapses is less understood compared to that of excitatory synapses. Quantum dot‐single particle tracking (QD‐SPT), a super‐resolution imaging technique that enables the analysis of membrane molecule dynamics at single‐molecule resolution, is a powerful tool to analyze the behavior of proteins and lipids on the plasma membrane. In this review, we summarize the recent application of QD‐SPT in understanding of GABAergic synaptic transmission. Here we introduce QD‐SPT experiments that provide further insights into the molecular mechanism supporting GABAergic synapses. QD‐SPT studies revealed that glutamate and Ca2+ signaling is involved in (a) the maintenance of GABAergic synapses, (b) GABAergic long‐term depression, and GABAergic long‐term potentiation, by specifically activating signaling pathways unique to each phenomenon. We also introduce a novel Ca2+ imaging technique to describe the diversity of Ca2+ signals that may activate the downstream signaling pathways that induce specific biological output.
Collapse
Affiliation(s)
- Hiroko Bannai
- School of Advanced Science and Engineering, Department of Electrical Engineering and Biosciences, Waseda University, Tokyo, Japan.,Department of Neurophysiology, Keio University School of Medicine, Tokyo, Japan.,Japan Science and Technology Agency, PRESTO, Kawaguchi, Saitama, Japan.,Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan
| | - Fumihiro Niwa
- Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan.,Institut de Biologie de l'ENS (IBENS), École Normale Supérieure, PSL Research University, INSERM, CNRS, Paris, France
| | - Shigeo Sakuragi
- School of Advanced Science and Engineering, Department of Electrical Engineering and Biosciences, Waseda University, Tokyo, Japan.,Department of Pharmacology, Faculty of Medicine, Yamagata University, Yamagata, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Center for Brain Science, Wako, Japan.,Shanghai Institute for Advanced Immunochemical Studies (SIAIS), ShanghaiTech University, Shanghai, China.,Department of Biomolecular Science, Faculty of Science, Toho University, Funabashi, Japan
| |
Collapse
|
16
|
Levchenko A, Nurgaliev T, Kanapin A, Samsonova A, Gainetdinov RR. Current challenges and possible future developments in personalized psychiatry with an emphasis on psychotic disorders. Heliyon 2020; 6:e03990. [PMID: 32462093 PMCID: PMC7240336 DOI: 10.1016/j.heliyon.2020.e03990] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 10/31/2019] [Accepted: 05/12/2020] [Indexed: 12/13/2022] Open
Abstract
A personalized medicine approach seems to be particularly applicable to psychiatry. Indeed, considering mental illness as deregulation, unique to each patient, of molecular pathways, governing the development and functioning of the brain, seems to be the most justified way to understand and treat disorders of this medical category. In order to extract correct information about the implicated molecular pathways, data can be drawn from sampling phenotypic and genetic biomarkers and then analyzed by a machine learning algorithm. This review describes current difficulties in the field of personalized psychiatry and gives several examples of possibly actionable biomarkers of psychotic and other psychiatric disorders, including several examples of genetic studies relevant to personalized psychiatry. Most of these biomarkers are not yet ready to be introduced in clinical practice. In a next step, a perspective on the path personalized psychiatry may take in the future is given, paying particular attention to machine learning algorithms that can be used with the goal of handling multidimensional datasets.
Collapse
Affiliation(s)
- Anastasia Levchenko
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, 7/9 Universitetskaya nab., Saint Petersburg, 199034, Russia
| | - Timur Nurgaliev
- Institute of Translational Biomedicine, Saint Petersburg State University, 7/9 Universitetskaya nab., Saint Petersburg, 199034, Russia
| | - Alexander Kanapin
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, 7/9 Universitetskaya nab., Saint Petersburg, 199034, Russia
| | - Anastasia Samsonova
- Theodosius Dobzhansky Center for Genome Bioinformatics, Saint Petersburg State University, 7/9 Universitetskaya nab., Saint Petersburg, 199034, Russia
| | - Raul R. Gainetdinov
- Institute of Translational Biomedicine, Saint Petersburg State University, 7/9 Universitetskaya nab., Saint Petersburg, 199034, Russia
| |
Collapse
|
17
|
Crosby KC, Gookin SE, Garcia JD, Hahm KM, Dell'Acqua ML, Smith KR. Nanoscale Subsynaptic Domains Underlie the Organization of the Inhibitory Synapse. Cell Rep 2020; 26:3284-3297.e3. [PMID: 30893601 DOI: 10.1016/j.celrep.2019.02.070] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 01/03/2019] [Accepted: 02/19/2019] [Indexed: 12/15/2022] Open
Abstract
Inhibitory synapses mediate the majority of synaptic inhibition in the brain, thereby controlling neuronal excitability, firing, and plasticity. Although essential for neuronal function, the central question of how these synapses are organized at the subsynaptic level remains unanswered. Here, we use three-dimensional (3D) super-resolution microscopy to image key components of the inhibitory postsynaptic domain and presynaptic terminal, revealing that inhibitory synapses are organized into nanoscale subsynaptic domains (SSDs) of the gephyrin scaffold, GABAARs and the active-zone protein Rab3-interacting molecule (RIM). Gephyrin SSDs cluster GABAAR SSDs, demonstrating nanoscale architectural interdependence between scaffold and receptor. GABAAR SSDs strongly associate with active-zone RIM SSDs, indicating an important role for GABAAR nanoscale organization near sites of GABA release. Finally, we find that in response to elevated activity, synapse growth is mediated by an increase in the number of postsynaptic SSDs, suggesting a modular mechanism for increasing inhibitory synaptic strength.
Collapse
Affiliation(s)
- Kevin C Crosby
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Sara E Gookin
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Joshua D Garcia
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Katlin M Hahm
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Katharine R Smith
- Department of Pharmacology, University of Colorado School of Medicine, Aurora, CO 80045, USA.
| |
Collapse
|
18
|
Davenport EC, Szulc BR, Drew J, Taylor J, Morgan T, Higgs NF, López-Doménech G, Kittler JT. Autism and Schizophrenia-Associated CYFIP1 Regulates the Balance of Synaptic Excitation and Inhibition. Cell Rep 2020; 26:2037-2051.e6. [PMID: 30784587 PMCID: PMC6381785 DOI: 10.1016/j.celrep.2019.01.092] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 10/26/2018] [Accepted: 01/24/2019] [Indexed: 12/28/2022] Open
Abstract
Altered excitatory/inhibitory (E/I) balance is implicated in neuropsychiatric and neurodevelopmental disorders, but the underlying genetic etiology remains poorly understood. Copy number variations in CYFIP1 are associated with autism, schizophrenia, and intellectual disability, but its role in regulating synaptic inhibition or E/I balance remains unclear. We show that CYFIP1, and the paralog CYFIP2, are enriched at inhibitory postsynaptic sites. While CYFIP1 or CYFIP2 upregulation increases excitatory synapse number and the frequency of miniature excitatory postsynaptic currents (mEPSCs), it has the opposite effect at inhibitory synapses, decreasing their size and the amplitude of miniature inhibitory postsynaptic currents (mIPSCs). Contrary to CYFIP1 upregulation, its loss in vivo, upon conditional knockout in neocortical principal cells, increases expression of postsynaptic GABAA receptor β2/3-subunits and neuroligin 3, enhancing synaptic inhibition. Thus, CYFIP1 dosage can bi-directionally impact inhibitory synaptic structure and function, potentially leading to altered E/I balance and circuit dysfunction in CYFIP1-associated neurological disorders. CYFIP1 and CYFIP2 are enriched at inhibitory synapses. CYFIP1 upregulation differentially disrupts inhibitory and excitatory synapses. Conditional loss of CYFIP1 alters neuroligin 3 and GABAAR β-subunits expression. Loss of CYFIP1 increases inhibitory synaptic clusters and hence mIPSC amplitude.
Collapse
Affiliation(s)
- Elizabeth C Davenport
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Blanka R Szulc
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - James Drew
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - James Taylor
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Toby Morgan
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Nathalie F Higgs
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Guillermo López-Doménech
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
| |
Collapse
|
19
|
Blanco-Luquin I, Acha B, Urdánoz-Casado A, Sánchez-Ruiz De Gordoa J, Vicuña-Urriza J, Roldán M, Labarga A, Zelaya MV, Cabello C, Méndez-López I, Mendioroz M. Early epigenetic changes of Alzheimer's disease in the human hippocampus. Epigenetics 2020; 15:1083-1092. [PMID: 32233750 DOI: 10.1080/15592294.2020.1748917] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The discovery of new biomarkers would be very valuable to improve the detection of early Alzheimer's disease (AD). DNA methylation marks may serve as epigenetic biomarkers of early AD. Here we identified epigenetic marks that are present in the human hippocampus from the earliest stages of AD. A previous methylome dataset of the human AD hippocampus was used to select a set of eight differentially methylated positions (DMPs) since early AD stages. Next, bisulphite pyrosequencing was performed in an expanded homogeneous cohort of 18 pure controls and 35 hippocampal samples with neuropathological changes of pure AD. Correlation between DNA methylation levels in DMPs and phospho-tau protein burden assessed by immunohistochemistry in the hippocampus was also determined. We found four DMPs showing higher levels of DNA methylation at early AD stages compared to controls, involving ELOVL2, GIT1/TP53I13 and the histone gene locus at chromosome 6. DNA methylation levels assessed by bisulphite pyrosequencing correlated with phospho-tau protein burden for ELOVL2 and HIST1H3E/HIST1H3 F genes. In this discovery study, a set of four epigenetic marks of early AD stages have been identified in the human hippocampus. It would be worth studying in-depth the specific pathways related to these epigenetic marks. These early alterations in DNA methylation in the AD hippocampus could be regarded as candidate biomarkers to be explored in future translational studies. ABBREVIATIONS AD: Alzheimer's disease; DMPs: Differentially methylated positions; CSF: Cerebrospinal fluid; βA42: β-amyloid 42; PET: positron emission tomography; 5mC: 5-methyl cytosine; CpG: cytosine-guanine dinucleotides; ANK1: ankyrin-1; BIN1: amphiphysin II; p-tau: hyperphosphorylated tau; CERAD: Consortium to Establish A Registry for Alzheimer's Disease; SD: standard deviation; ANOVA: one-way analysis of variance; VLCFAs: very long-chain fatty acids; DHA: docosahexaenoic acid; mTOR: mechanistic target of rapamycin.
Collapse
Affiliation(s)
- Idoia Blanco-Luquin
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Blanca Acha
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Amaya Urdánoz-Casado
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Javier Sánchez-Ruiz De Gordoa
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain.,Department of Neurology, Complejo Hospitalario De Navarra- IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Janire Vicuña-Urriza
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Miren Roldán
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Alberto Labarga
- Bioinformatics Unit, Navarrabiomed, Public University of Navarre (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - María Victoria Zelaya
- Department of Pathology, Complejo Hospitalario De Navarra- IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Carolina Cabello
- Department of Neurology, Complejo Hospitalario De Navarra- IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| | - Iván Méndez-López
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain.,Department of Internal Medicine, Hospital García-Orcoyen , Estella, Spain
| | - Maite Mendioroz
- Neuroepigenetics Laboratory-Navarrabiomed, Complejo Hospitalario De Navarra, Universidad Pública De Navarra (UPNA), IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain.,Department of Neurology, Complejo Hospitalario De Navarra- IdiSNA (Navarra Institute for Health Research) , Pamplona, Spain
| |
Collapse
|
20
|
Kim H, Jung H, Jung H, Kwon SK, Ko J, Um JW. The small GTPase ARF6 regulates GABAergic synapse development. Mol Brain 2020; 13:2. [PMID: 31907062 PMCID: PMC6945580 DOI: 10.1186/s13041-019-0543-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
ADP ribosylation factors (ARFs) are a family of small GTPases composed of six members (ARF1-6) that control various cellular functions, including membrane trafficking and actin cytoskeletal rearrangement, in eukaryotic cells. Among them, ARF1 and ARF6 are the most studied in neurons, particularly at glutamatergic synapses, but their roles at GABAergic synapses have not been investigated. Here, we show that a subset of ARF6 protein is localized at GABAergic synapses in cultured hippocampal neurons. In addition, we found that knockdown (KD) of ARF6, but not ARF1, triggered a reduction in the number of GABAergic synaptic puncta in mature cultured neurons in an ARF activity-dependent manner. ARF6 KD also reduced GABAergic synaptic density in the mouse hippocampal dentate gyrus (DG) region. Furthermore, ARF6 KD in the DG increased seizure susceptibility in an induced epilepsy model. Viewed together, our results suggest that modulating ARF6 and its regulators could be a therapeutic strategy against brain pathologies involving hippocampal network dysfunction, such as epilepsy.
Collapse
Affiliation(s)
- Hyeonho Kim
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyeji Jung
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Hyunsu Jung
- Division of Life Sciences, Korea University, Seoul, 02841, South Korea.,Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Seok-Kyu Kwon
- Center for Functional Connectomics, Brain Science Institute, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Jaewon Ko
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea
| | - Ji Won Um
- Department of Brain and Cognitive Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 333 Techno Jungangdae-Ro, Hyeonpoong-eup, Dalseong-gun, Daegu, 42988, South Korea.
| |
Collapse
|
21
|
Kwon Y, Lee SJ, Lee E, Kim D, Park D. βPix heterozygous mice have defects in neuronal morphology and social interaction. Biochem Biophys Res Commun 2019; 516:1204-1210. [PMID: 31296385 DOI: 10.1016/j.bbrc.2019.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/01/2019] [Indexed: 11/20/2022]
Abstract
βPix activates Rho family small GTPases, Rac1 and Cdc42 as a guanine nucleotide exchange factor. Although overexpression of βPix in cultured neurons indicates that βPix is involved in spine morphogenesis and synapse formation in vitro, the in vivo role of βPix in the neuron is not well understood. Recently, we generated βPix knockout mice that showed lethality at embryonic day 9.5. Here, we investigate the neuronal role of βPix using βPix heterozygous mice that are viable and fertile. βPix heterozygous mice show decreased expression levels of βPix proteins in various tissues including the brain. Cultured hippocampal neurons from βPix heterozygous mice show a decrease in neurite length and complexity as well as synaptic density. Both excitatory and inhibitory synapse densities are decreased in these neurons. Golgi-staining of hippocampal tissues from the brain of these mice show reduced dendritic complexity and spine density in the hippocampal neurons. Expression levels of NMDA- and AMPA-receptor subunits and Git1 protein in hippocampal tissues are also decreased in these mice. Behaviorally, βPix heterozygous mice exhibit impaired social interaction. Altogether, these results indicate that βPix is required for neurite morphogenesis and synapse formation, and the reduced expression of βPix proteins results in a defect in social behavior.
Collapse
Affiliation(s)
- Younghee Kwon
- School of Biological Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| | - Seung Joon Lee
- Computational Biology & Genomics, Biogen, Cambridge, MA, 02142, USA.
| | - Eunee Lee
- Department of Anatomy, College of Medicine, Yonsei University, Seoul, 03722, Republic of Korea.
| | - Daesoo Kim
- Department of Biological Sciences, KAIST, Daejeon, 34141, Republic of Korea.
| | - Dongeun Park
- School of Biological Sciences, Seoul National University, Seoul, 08826, Republic of Korea.
| |
Collapse
|
22
|
Activity-dependent development of GABAergic synapses. Brain Res 2019; 1707:18-26. [DOI: 10.1016/j.brainres.2018.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 11/05/2018] [Accepted: 11/10/2018] [Indexed: 12/20/2022]
|
23
|
Lorenz-Guertin JM, Bambino MJ, Jacob TC. γ2 GABA AR Trafficking and the Consequences of Human Genetic Variation. Front Cell Neurosci 2018; 12:265. [PMID: 30190672 PMCID: PMC6116786 DOI: 10.3389/fncel.2018.00265] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/02/2018] [Indexed: 11/13/2022] Open
Abstract
GABA type A receptors (GABAARs) mediate the majority of fast inhibitory neurotransmission in the central nervous system (CNS). Most prevalent as heteropentamers composed of two α, two β, and a γ2 subunit, these ligand-gated ionotropic chloride channels are capable of extensive genetic diversity (α1-6, β1-3, γ1-3, δ, 𝜀, 𝜃, π, ρ1-3). Part of this selective GABAAR assembly arises from the critical role for γ2 in maintaining synaptic receptor localization and function. Accordingly, mutations in this subunit account for over half of the known epilepsy-associated genetic anomalies identified in GABAARs. Fundamental structure-function studies and cellular pathology investigations have revealed dynamic GABAAR trafficking and synaptic scaffolding as critical regulators of GABAergic inhibition. Here, we introduce in vitro and in vivo findings regarding the specific role of the γ2 subunit in receptor trafficking. We then examine γ2 subunit human genetic variation and assess disease related phenotypes and the potential role of altered GABAAR trafficking. Finally, we discuss new-age imaging techniques and their potential to provide novel insight into critical regulatory mechanisms of GABAAR function.
Collapse
Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Matthew J Bambino
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| |
Collapse
|
24
|
López Tobón A, Suresh M, Jin J, Vitriolo A, Pietralla T, Tedford K, Bossenz M, Mahnken K, Kiefer F, Testa G, Fischer KD, Püschel AW. The guanine nucleotide exchange factor Arhgef7/βPix promotes axon formation upstream of TC10. Sci Rep 2018; 8:8811. [PMID: 29891904 PMCID: PMC5995858 DOI: 10.1038/s41598-018-27081-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/29/2018] [Indexed: 11/10/2022] Open
Abstract
The characteristic six layers of the mammalian neocortex develop sequentially as neurons are generated by neural progenitors and subsequently migrate past older neurons to their final position in the cortical plate. One of the earliest steps of neuronal differentiation is the formation of an axon. Small GTPases play essential roles during this process by regulating cytoskeletal dynamics and intracellular trafficking. While the function of GTPases has been studied extensively in cultured neurons and in vivo much less is known about their upstream regulators. Here we show that Arhgef7 (also called βPix or Cool1) is essential for axon formation during cortical development. The loss of Arhgef7 results in an extensive loss of axons in cultured neurons and in the developing cortex. Arhgef7 is a guanine-nucleotide exchange factor (GEF) for Cdc42, a GTPase that has a central role in directing the formation of axons during brain development. However, active Cdc42 was not able to rescue the knockdown of Arhgef7. We show that Arhgef7 interacts with the GTPase TC10 that is closely related to Cdc42. Expression of active TC10 can restore the ability to extend axons in Arhgef7-deficient neurons. Our results identify an essential role of Arhgef7 during neuronal development that promotes axon formation upstream of TC10.
Collapse
Affiliation(s)
- Alejandro López Tobón
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.,Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Megalakshmi Suresh
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany
| | - Jing Jin
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany.,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany
| | - Alessandro Vitriolo
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Thorben Pietralla
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany
| | - Kerry Tedford
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Michael Bossenz
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Kristina Mahnken
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany
| | - Friedemann Kiefer
- Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.,Max-Planck-Institute for Molecular Biomedicine, Mammalian cell signaling laboratory, Röntgenstr. 20, D-48149, Münster, Germany.,European Institute for Molecular Imaging, Westfälische Wilhelms-Universität, Waldeyerstr. 15, D-48149, Münster, Germany
| | - Giuseppe Testa
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, 20122, Italy.,European Institute of Oncology, Via Adamello 16, 20139, Milan, Italy
| | - Klaus-Dieter Fischer
- Institut für Biochemie und Zellbiologie, Otto-von-Guericke-University, Medical Faculty, Leipziger Str. 44, 39120, Magdeburg, 39120, Germany
| | - Andreas W Püschel
- Institut für Molekulare Zellbiologie, Westfälische Wilhelms-Universität, Schloßplatz 5, D-48149, Münster, Germany. .,Cells-in-Motion Cluster of Excellence, University of Münster, D-48149, Münster, Germany.
| |
Collapse
|
25
|
Modi S, Higgs NF, Sheehan D, Griffin LD, Kittler JT. Quantum dot conjugated nanobodies for multiplex imaging of protein dynamics at synapses. NANOSCALE 2018; 10:10241-10249. [PMID: 29790493 PMCID: PMC5977936 DOI: 10.1039/c7nr09130c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 05/12/2018] [Indexed: 06/08/2023]
Abstract
Neurons communicate with each other through synapses, which show enrichment for specialized receptors. Although many studies have explored spatial enrichment and diffusion of these receptors in dissociated neurons using single particle tracking, much less is known about their dynamic properties at synapses in complex tissue like brain slices. Here we report the use of smaller and highly specific quantum dots conjugated with a recombinant single domain antibody fragment (VHH fragment) against green fluorescent protein to provide information on diffusion of adhesion molecules at the growth cone and neurotransmitter receptors at synapses. Our data reveals that QD-nanobodies can measure neurotransmitter receptor dynamics at both excitatory and inhibitory synapses in primary neuronal cultures as well as in ex vivo rat brain slices. We also demonstrate that this approach can be applied to tagging multiple proteins to simultaneously monitor their behavior. Thus, we provide a strategy for multiplex imaging of tagged membrane proteins to study their clustering, diffusion and transport both in vitro as well as in native tissue environments such as brain slices.
Collapse
Affiliation(s)
- Souvik Modi
- Neuroscience
, Physiology and Pharmacology
, University College London. Gower Street
,
London
, WC1E 6BT
, UK
.
- Tata Institute of Fundamental Research
,
Homi Bhabha Road
, Mumbai
, 400005
, India
| | - Nathalie F. Higgs
- Neuroscience
, Physiology and Pharmacology
, University College London. Gower Street
,
London
, WC1E 6BT
, UK
.
| | - David Sheehan
- Neuroscience
, Physiology and Pharmacology
, University College London. Gower Street
,
London
, WC1E 6BT
, UK
.
| | | | - Josef T. Kittler
- Neuroscience
, Physiology and Pharmacology
, University College London. Gower Street
,
London
, WC1E 6BT
, UK
.
| |
Collapse
|
26
|
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
Collapse
|
27
|
GIT1 regulates synaptic structural plasticity underlying learning. PLoS One 2018; 13:e0194350. [PMID: 29554125 PMCID: PMC5858814 DOI: 10.1371/journal.pone.0194350] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 03/01/2018] [Indexed: 11/19/2022] Open
Abstract
The signaling scaffold protein GIT1 is expressed widely throughout the brain, but its function in vivo remains elusive. Mice lacking GIT1 have been proposed as a model for attention deficit-hyperactivity disorder, due to alterations in basal locomotor activity as well as paradoxical locomotor suppression by the psychostimulant amphetamine. Since we had previously shown that GIT1-knockout mice have normal locomotor activity, here we examined GIT1-deficient mice for ADHD-like behavior in more detail, and find neither hyperactivity nor amphetamine-induced locomotor suppression. Instead, GIT1-deficient mice exhibit profound learning and memory defects and reduced synaptic structural plasticity, consistent with an intellectual disability phenotype. We conclude that loss of GIT1 alone is insufficient to drive a robust ADHD phenotype in distinct strains of mice. In contrast, multiple learning and memory defects have been observed here and in other studies using distinct GIT1-knockout lines, consistent with a predominant intellectual disability phenotype related to altered synaptic structural plasticity.
Collapse
|
28
|
Lorenz-Guertin JM, Jacob TC. GABA type a receptor trafficking and the architecture of synaptic inhibition. Dev Neurobiol 2018; 78:238-270. [PMID: 28901728 PMCID: PMC6589839 DOI: 10.1002/dneu.22536] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/08/2017] [Accepted: 09/08/2017] [Indexed: 12/21/2022]
Abstract
Ubiquitous expression of GABA type A receptors (GABAA R) in the central nervous system establishes their central role in coordinating most aspects of neural function and development. Dysregulation of GABAergic neurotransmission manifests in a number of human health disorders and conditions that in certain cases can be alleviated by drugs targeting these receptors. Precise changes in the quantity or activity of GABAA Rs localized at the cell surface and at GABAergic postsynaptic sites directly impact the strength of inhibition. The molecular mechanisms constituting receptor trafficking to and from these compartments therefore dictate the efficacy of GABAA R function. Here we review the current understanding of how GABAA Rs traffic through biogenesis, plasma membrane transport, and degradation. Emphasis is placed on discussing novel GABAergic synaptic proteins, receptor and scaffolding post-translational modifications, activity-dependent changes in GABAA R confinement, and neuropeptide and neurosteroid mediated changes. We further highlight modern techniques currently advancing the knowledge of GABAA R trafficking and clinically relevant neurodevelopmental diseases connected to GABAergic dysfunction. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 238-270, 2018.
Collapse
Affiliation(s)
- Joshua M Lorenz-Guertin
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261
| |
Collapse
|
29
|
Acevedo A, González-Billault C. Crosstalk between Rac1-mediated actin regulation and ROS production. Free Radic Biol Med 2018; 116:101-113. [PMID: 29330095 DOI: 10.1016/j.freeradbiomed.2018.01.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 01/03/2018] [Accepted: 01/05/2018] [Indexed: 02/08/2023]
Abstract
The small RhoGTPase Rac1 is implicated in a variety of events related to actin cytoskeleton rearrangement. Remarkably, another event that is completely different from those related to actin regulation has the same relevance; the Rac1-mediated production of reactive oxygen species (ROS) through NADPH oxidases (NOX). Each outcome involves different Rac1 downstream effectors; on one hand, events related to the actin cytoskeleton require Rac1 to bind to WAVEs proteins and PAKs that ultimately promote actin branching and turnover, on the other, NOX-derived ROS production demands active Rac1 to be bound to a cytosolic activator of NOX. How Rac1-mediated signaling ends up promoting actin-related events, NOX-derived ROS, or both is poorly understood. Rac1 regulators, including scaffold proteins, are known to exert tight control over its functions. Hence, evidence of Rac1 regulatory events leading to both actin remodeling and NOX-mediated ROS generation are discussed. Moreover, cellular functions linked to physiological and pathological conditions that exhibit crosstalk between Rac1 outcomes are analyzed, while plausible roles in neuronal functions (and dysfunctions) are highlighted. Together, discussed evidence shed light on cellular mechanisms which requires Rac1 to direct either actin- and/or ROS-related events, helping to understand crucial roles of Rac1 dual functionality.
Collapse
Affiliation(s)
- Alejandro Acevedo
- FONDAP Geroscience Center for Brain Health and Metabolism, Santiago, Chile.
| | - Christian González-Billault
- FONDAP Geroscience Center for Brain Health and Metabolism, Santiago, Chile; Department of Biology, Faculty of Sciences, Universidad de Chile, 7800024, Chile; The Buck Institute for Research on Aging, Novato, USA.
| |
Collapse
|
30
|
Activity-Dependent Inhibitory Synapse Scaling Is Determined by Gephyrin Phosphorylation and Subsequent Regulation of GABA A Receptor Diffusion. eNeuro 2018; 5:eN-NWR-0203-17. [PMID: 29379879 PMCID: PMC5780843 DOI: 10.1523/eneuro.0203-17.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 12/14/2017] [Accepted: 12/21/2017] [Indexed: 12/21/2022] Open
Abstract
Synaptic plasticity relies on the rapid changes in neurotransmitter receptor number at postsynaptic sites. Using superresolution photoactivatable localization microscopy imaging and quantum dot-based single-particle tracking in rat hippocampal cultured neurons, we investigated whether the phosphorylation status of the main scaffolding protein gephyrin influenced the organization of the gephyrin scaffold and GABAA receptor (GABAAR) membrane dynamics. We found that gephyrin phosphorylation regulates gephyrin microdomain compaction. Extracellular signal-regulated kinase 1/2 and glycogen synthase kinase 3β (GSK3β) signaling alter the gephyrin scaffold mesh differentially. Differences in scaffold organization similarly affected the diffusion of synaptic GABAARs, suggesting reduced gephyrin receptor-binding properties. In the context of synaptic scaling, our results identify a novel role of the GSK3β signaling pathway in the activity-dependent regulation of extrasynaptic receptor surface trafficking and GSK3β, protein kinase A, and calcium/calmodulin-dependent protein kinase IIα pathways in facilitating adaptations of synaptic receptors.
Collapse
|
31
|
Selten M, van Bokhoven H, Nadif Kasri N. Inhibitory control of the excitatory/inhibitory balance in psychiatric disorders. F1000Res 2018; 7:23. [PMID: 29375819 PMCID: PMC5760969 DOI: 10.12688/f1000research.12155.1] [Citation(s) in RCA: 122] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/21/2017] [Indexed: 12/21/2022] Open
Abstract
Neuronal networks consist of different types of neurons that all play their own role in order to maintain proper network function. The two main types of neurons segregate in excitatory and inhibitory neurons, which together regulate the flow of information through the network. It has been proposed that changes in the relative strength in these two opposing forces underlie the symptoms observed in psychiatric disorders, including autism and schizophrenia. Here, we review the role of alterations to the function of the inhibitory system as a cause of psychiatric disorders. First, we explore both patient and post-mortem evidence of inhibitory deficiency. We then discuss the function of different interneuron subtypes in the network and focus on the central role of a specific class of inhibitory neurons, parvalbumin-positive interneurons. Finally, we discuss genes known to be affected in different disorders and the effects that mutations in these genes have on the inhibitory system in cortex and hippocampus. We conclude that alterations to the inhibitory system are consistently identified in animal models of psychiatric disorders and, more specifically, that mutations affecting the function of parvalbumin-positive interneurons seem to play a central role in the symptoms observed in these disorders.
Collapse
Affiliation(s)
- Martijn Selten
- Centre for Developmental Neurobiology, Institute of Psychiatry, Psychology and Neuroscience, New Hunt's House, Guy's Campus, King's College London, London, SE1 1UL, UK.,MRC Centre for Neurodevelopmental Disorders, New Hunt's House, Guy's Campus, King's College London, London, SE1 1UL, UK.,Department of Human Genetics & Department of Cognitive Neuroscience, Radboudumc, Geert Grooteplein 10, Box 9101, 6500 HB Nijmegen, Netherlands.,Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, Netherlands
| | - Hans van Bokhoven
- Department of Human Genetics & Department of Cognitive Neuroscience, Radboudumc, Geert Grooteplein 10, Box 9101, 6500 HB Nijmegen, Netherlands.,Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, Netherlands
| | - Nael Nadif Kasri
- Department of Human Genetics & Department of Cognitive Neuroscience, Radboudumc, Geert Grooteplein 10, Box 9101, 6500 HB Nijmegen, Netherlands.,Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, 6525 AJ Nijmegen, Netherlands
| |
Collapse
|
32
|
Al Awabdh S, Gupta-Agarwal S, Sheehan DF, Muir J, Norkett R, Twelvetrees AE, Griffin LD, Kittler JT. Neuronal activity mediated regulation of glutamate transporter GLT-1 surface diffusion in rat astrocytes in dissociated and slice cultures. Glia 2018; 64:1252-64. [PMID: 27189737 PMCID: PMC4915597 DOI: 10.1002/glia.22997] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 04/03/2016] [Accepted: 04/13/2016] [Indexed: 11/17/2022]
Abstract
The astrocytic GLT‐1 (or EAAT2) is the major glutamate transporter for clearing synaptic glutamate. While the diffusion dynamics of neurotransmitter receptors at the neuronal surface are well understood, far less is known regarding the surface trafficking of transporters in subcellular domains of the astrocyte membrane. Here, we have used live‐cell imaging to study the mechanisms regulating GLT‐1 surface diffusion in astrocytes in dissociated and brain slice cultures. Using GFP‐time lapse imaging, we show that GLT‐1 forms stable clusters that are dispersed rapidly and reversibly upon glutamate treatment in a transporter activity‐dependent manner. Fluorescence recovery after photobleaching and single particle tracking using quantum dots revealed that clustered GLT‐1 is more stable than diffuse GLT‐1 and that glutamate increases GLT‐1 surface diffusion in the astrocyte membrane. Interestingly, the two main GLT‐1 isoforms expressed in the brain, GLT‐1a and GLT‐1b, are both found to be stabilized opposed to synapses under basal conditions, with GLT‐1b more so. GLT‐1 surface mobility is increased in proximity to activated synapses and alterations of neuronal activity can bidirectionally modulate the dynamics of both GLT‐1 isoforms. Altogether, these data reveal that astrocytic GLT‐1 surface mobility, via its transport activity, is modulated during neuronal firing, which may be a key process for shaping glutamate clearance and glutamatergic synaptic transmission. GLIA 2016;64:1252–1264
Collapse
Affiliation(s)
- Sana Al Awabdh
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - Swati Gupta-Agarwal
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - David F Sheehan
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - James Muir
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - Rosalind Norkett
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - Alison E Twelvetrees
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| | - Lewis D Griffin
- Department of Computer Science, University College London, United Kingdom
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, United Kingdom
| |
Collapse
|
33
|
Functional analysis of rare variants found in schizophrenia implicates a critical role for GIT1-PAK3 signaling in neuroplasticity. Mol Psychiatry 2017; 22:417-429. [PMID: 27457813 PMCID: PMC6186433 DOI: 10.1038/mp.2016.98] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/21/2016] [Accepted: 05/02/2016] [Indexed: 01/21/2023]
Abstract
Although the pathogenesis of schizophrenia (SCZ) is proposed to involve alterations of neural circuits via synaptic dysfunction, the underlying molecular mechanisms remain poorly understood. Recent exome sequencing studies of SCZ have uncovered numerous single-nucleotide variants (SNVs); however, the majority of these SNVs have unknown functional consequences, leaving their disease relevance uncertain. Filling this knowledge gap requires systematic application of quantitative and scalable assays to assess known and novel biological functions of genes. Here we demonstrate loss-of-function effects of multiple rare coding SNVs found in SCZ subjects in the GIT1 (G protein-coupled receptor kinase interacting ArfGAP 1) gene using functional cell-based assays involving coexpression of GIT1 and PAK3 (p21 protein (Cdc42/Rac)-activated kinase 3). Most notably, a GIT1-R283W variant reported in four independent SCZ cases was defective in activating PAK3 as well as MAPK (mitogen-activated protein kinase). Similar functional deficits were found for a de novo SCZ variant GIT1-S601N. Additional assays revealed deficits in the capacity of GIT1-R283W to stimulate PAK phosphorylation in cultured hippocampal neurons. In addition, GIT1-R283W showed deficits in the induction of GAD1 (glutamate decarboxylase 1) protein expression. Extending these functional assays to 10 additional rare GIT1 variants revealed the existence of an allelic series with the majority of the SCZ case variants exhibiting loss of function toward MAPK activation in a manner correlated with loss of PAK3 activation. Taken together, we propose that rare variants in GIT1, along with other genetic and environmental factors, cause dysregulation of PAK3 leading to synaptic deficits in SCZ.
Collapse
|
34
|
Cervera-Juanes R, Wilhelm LJ, Park B, Grant KA, Ferguson B. Alcohol-dose-dependent DNA methylation and expression in the nucleus accumbens identifies coordinated regulation of synaptic genes. Transl Psychiatry 2017; 7:e994. [PMID: 28072409 PMCID: PMC5545731 DOI: 10.1038/tp.2016.266] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/09/2016] [Accepted: 11/13/2016] [Indexed: 12/20/2022] Open
Abstract
Alterations in DNA methylation have been associated with alcohol exposure and proposed to contribute to continued alcohol use; however, the molecular mechanisms involved remain obscure. We investigated the escalating effects of alcohol use on DNA methylation, gene expression and predicted neural effects in the nucleus accumbens of rhesus macaques that self-administered 4% alcohol for over 12 months. Using an exploratory approach to identify CpG-rich regions, followed by bisulfite sequencing, the methylation levels of 2.7 million CpGs were compared between seven low-binge drinkers and nine heavy-very heavy drinking subjects. We identified 17 significant differential methylation regions (DMRs), including 14 with methylation levels that were correlated with average daily alcohol consumption. The size of the DMRs ranged from 29 to 158 bp (mean=63.7), included 4-19 CpGs per DMR (mean=8.06) and spanned a range of average methylation values from 5 to 34%. Eight of the DMRs mapped to genes implicated in modulating synaptic plasticity. Six of the synaptic genes have not previously been linked to alcohol use. Validation studies of these eight DMRs using bisulfite amplicon sequencing and an expanded set of 30 subjects confirmed the significant alcohol-dose-associated methylation of the DMRs. Expression analysis of three of the DMR-associated genes, LRP5, GPR39 and JAKMIP1, revealed significant correlations between DMR methylation and whole-gene or alternative transcript expression, supporting a functional role in regulating gene expression. Together, these studies suggest that alcohol-associated synaptic remodeling may be regulated and coordinated at the level of DNA methylation.
Collapse
Affiliation(s)
- R Cervera-Juanes
- Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - L J Wilhelm
- Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - B Park
- Department of Public Health and Preventive Medicine, Oregon Health and Science University, Portland, OR, USA
| | - K A Grant
- Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - B Ferguson
- Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA,Department of Neurosciences, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA. E-mail:
| |
Collapse
|
35
|
Mele M, Leal G, Duarte CB. Role of GABAAR trafficking in the plasticity of inhibitory synapses. J Neurochem 2016; 139:997-1018. [DOI: 10.1111/jnc.13742] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/12/2016] [Accepted: 07/13/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Miranda Mele
- Center for Neuroscience and Cell Biology; University of Coimbra; Coimbra Portugal
| | - Graciano Leal
- Center for Neuroscience and Cell Biology; University of Coimbra; Coimbra Portugal
| | - Carlos B. Duarte
- Center for Neuroscience and Cell Biology; University of Coimbra; Coimbra Portugal
- Department of Life Sciences; University of Coimbra; Coimbra Portugal
| |
Collapse
|
36
|
Expression of p21-activated kinases 1 and 3 is altered in the brain of subjects with depression. Neuroscience 2016; 333:331-44. [PMID: 27474226 DOI: 10.1016/j.neuroscience.2016.07.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 07/13/2016] [Accepted: 07/21/2016] [Indexed: 01/25/2023]
Abstract
The p21-activated kinases (PAKs) of group I are the main effectors for the small Rho GTPases, critically involved in neurodevelopment, plasticity and maturation of the nervous system. Moreover, the neuronal complexity controlled by PAK1/PAK3 signaling determines the postnatal brain size and synaptic properties. Stress induces alterations at the level of structural and functional synaptic plasticity accompanied by reductions in size and activity of the hippocampus and the prefrontal cortex (PFC). These abnormalities are likely to contribute to the pathology of depression and, in part, reflect impaired cytoskeleton remodeling pointing to the role of Rho GTPase signaling. Thus, the present study assessed the expression of the group I PAKs and their activators in the brain of depressed subjects. Using quantitative polymerase chain reaction (qPCR), mRNA levels and coexpression of the group I PAKs: PAK1, PAK2, and PAK3 as well as of their activators: RAC1, CDC42 and ARHGEF7 were examined in postmortem samples from the PFC (n=25) and the hippocampus (n=23) of subjects with depression and compared to control subjects (PFC n=24; hippocampus n=21). Results demonstrated that mRNA levels of PAK1 and PAK3, are significantly reduced in the brain of depressed subjects, with PAK1 being reduced in the PFC and PAK3 in the hippocampus. No differences were observed for the ubiquitously expressed PAK2. Following analysis of gene coexpression demonstrated disruption of coordinated gene expression in the brain of subjects with depression. Abnormalities in mRNA expression of PAK1 and PAK3 as well as their altered coexpression patterns were detected in the brain of subjects with depression.
Collapse
|
37
|
Kumar A, Paeger L, Kosmas K, Kloppenburg P, Noegel AA, Peche VS. Neuronal Actin Dynamics, Spine Density and Neuronal Dendritic Complexity Are Regulated by CAP2. Front Cell Neurosci 2016; 10:180. [PMID: 27507934 PMCID: PMC4960234 DOI: 10.3389/fncel.2016.00180] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 07/04/2016] [Indexed: 11/29/2022] Open
Abstract
Actin remodeling is crucial for dendritic spine development, morphology and density. CAP2 is a regulator of actin dynamics through sequestering G-actin and severing F-actin. In a mouse model, ablation of CAP2 leads to cardiovascular defects and delayed wound healing. This report investigates the role of CAP2 in the brain using Cap2gt/gt mice. Dendritic complexity, the number and morphology of dendritic spines were altered in Cap2gt/gt with increased number of excitatory synapses. This was accompanied by increased F-actin content and F-actin accumulation in cultured Cap2gt/gt neurons. Moreover, reduced surface GluA1 was observed in mutant neurons under basal condition and after induction of chemical LTP. Additionally, we show an interaction between CAP2 and n-cofilin, presumably mediated through the C-terminal domain of CAP2 and dependent on cofilin Ser3 phosphorylation. In vivo, the consequences of this interaction were altered phosphorylated cofilin levels and formation of cofilin aggregates in the neurons. Thus, our studies identify a novel role of CAP2 in neuronal development and neuronal actin dynamics.
Collapse
Affiliation(s)
- Atul Kumar
- Institute of Biochemistry I, Medical Faculty, University of Cologne, CologneGermany; Center for Molecular Medicine Cologne, University of Cologne, CologneGermany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany
| | - Lars Paeger
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany; Biocenter, Institute for Zoology, University of Cologne, CologneGermany
| | - Kosmas Kosmas
- Institute of Biochemistry I, Medical Faculty, University of Cologne, CologneGermany; Center for Molecular Medicine Cologne, University of Cologne, CologneGermany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany
| | - Peter Kloppenburg
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany; Biocenter, Institute for Zoology, University of Cologne, CologneGermany
| | - Angelika A Noegel
- Institute of Biochemistry I, Medical Faculty, University of Cologne, CologneGermany; Center for Molecular Medicine Cologne, University of Cologne, CologneGermany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany
| | - Vivek S Peche
- Institute of Biochemistry I, Medical Faculty, University of Cologne, CologneGermany; Center for Molecular Medicine Cologne, University of Cologne, CologneGermany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, CologneGermany
| |
Collapse
|
38
|
Devine MJ, Norkett R, Kittler JT. DISC1 is a coordinator of intracellular trafficking to shape neuronal development and connectivity. J Physiol 2016; 594:5459-69. [PMID: 27121900 DOI: 10.1113/jp272187] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/31/2016] [Indexed: 01/14/2023] Open
Abstract
The long, asymmetric and specialised architecture of neuronal processes necessitates a properly regulated transport network of molecular motors and cytoskeletal tracks. This allows appropriate distribution of cargo for correct formation and activity of the synapse, and thus normal neuronal communication. This communication is impaired in psychiatric disease, and ongoing studies have proposed that Disrupted in schizophrenia 1 (DISC1) is an important genetic risk factor for these disorders. The mechanisms by which DISC1 dysfunction might increase propensity to psychiatric disease are not completely understood; however, an emerging theme is that DISC1 can function as a key regulator of neuronal intracellular trafficking. Transport of a wide range of potential cargoes - including mRNAs, neurotransmitter receptors, vesicles and mitochondria - can be modulated by DISC1, and therefore is susceptible to DISC1 dysfunction. This theme highlights the importance of understanding precisely how DISC1 can regulate intracellular trafficking, and suggests that a novel approach to the treatment of psychiatric disorders could be provided by targeting this protein and the trafficking machinery with which it interacts.
Collapse
Affiliation(s)
- M J Devine
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - R Norkett
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - J T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK.
| |
Collapse
|
39
|
Li YS, Qin LX, Liu J, Xia WL, Li JP, Shen HL, Gao WQ. GIT1 enhances neurite outgrowth by stimulating microtubule assembly. Neural Regen Res 2016; 11:427-34. [PMID: 27127481 PMCID: PMC4829007 DOI: 10.4103/1673-5374.179054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
GIT1, a G-protein-coupled receptor kinase interacting protein, has been reported to be involved in neurite outgrowth. However, the neurobiological functions of the protein remain unclear. In this study, we found that GIT1 was highly expressed in the nervous system, and its expression was maintained throughout all stages of neuritogenesis in the brain. In primary cultured mouse hippocampal neurons from GIT1 knockout mice, there was a significant reduction in total neurite length per neuron, as well as in the average length of axon-like structures, which could not be prevented by nerve growth factor treatment. Overexpression of GIT1 significantly promoted axon growth and fully rescued the axon outgrowth defect in the primary hippocampal neuron cultures from GIT1 knockout mice. The GIT1 N terminal region, including the ADP ribosylation factor-GTPase activating protein domain, the ankyrin domains and the Spa2 homology domain, were sufficient to enhance axonal extension. Importantly, GIT1 bound to many tubulin proteins and microtubule-associated proteins, and it accelerated microtubule assembly in vitro. Collectively, our findings suggest that GIT1 promotes neurite outgrowth, at least partially by stimulating microtubule assembly. This study provides new insight into the cellular and molecular pathogenesis of GIT1-associated neurological diseases.
Collapse
Affiliation(s)
- Yi-Sheng Li
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Li-Xia Qin
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Jie Liu
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Wei-Liang Xia
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Jian-Ping Li
- Department of Neurology, Shanghai Renji Hospital, Shanghai, China
| | - Hai-Lian Shen
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China
| | - Wei-Qiang Gao
- State Key Laboratory of Oncogenes and Related Genes, Renji-Med X Stem Cell Research Center, Ren Ji Hospital, School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Shanghai, China; Collarative Innovation Center of Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| |
Collapse
|
40
|
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.
Collapse
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
| |
Collapse
|
41
|
Miro1 Regulates Activity-Driven Positioning of Mitochondria within Astrocytic Processes Apposed to Synapses to Regulate Intracellular Calcium Signaling. J Neurosci 2016; 35:15996-6011. [PMID: 26631479 DOI: 10.1523/jneurosci.2068-15.2015] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
It is fast emerging that maintaining mitochondrial function is important for regulating astrocyte function, although the specific mechanisms that govern astrocyte mitochondrial trafficking and positioning remain poorly understood. The mitochondrial Rho-GTPase 1 protein (Miro1) regulates mitochondrial trafficking and detachment from the microtubule transport network to control activity-dependent mitochondrial positioning in neurons. However, whether Miro proteins are important for regulating signaling-dependent mitochondrial dynamics in astrocytic processes remains unclear. Using live-cell confocal microscopy of rat organotypic hippocampal slices, we find that enhancing neuronal activity induces transient mitochondrial remodeling in astrocytes, with a concomitant, transient reduction in mitochondrial trafficking, mediated by elevations in intracellular Ca(2+). Stimulating neuronal activity also induced mitochondrial confinement within astrocytic processes in close proximity to synapses. Furthermore, we show that the Ca(2+)-sensing EF-hand domains of Miro1 are important for regulating mitochondrial trafficking in astrocytes and required for activity-driven mitochondrial confinement near synapses. Additionally, activity-dependent mitochondrial positioning by Miro1 reciprocally regulates the levels of intracellular Ca(2+) in astrocytic processes. Thus, the regulation of intracellular Ca(2+) signaling, dependent on Miro1-mediated mitochondrial positioning, could have important consequences for astrocyte Ca(2+) wave propagation, gliotransmission, and ultimately neuronal function.
Collapse
|
42
|
Ryu JR, Jang MJ, Jo Y, Joo S, Lee DH, Lee BY, Nam Y, Sun W. Synaptic compartmentalization by micropatterned masking of a surface adhesive cue in cultured neurons. Biomaterials 2016; 92:46-56. [PMID: 27035488 DOI: 10.1016/j.biomaterials.2016.03.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 10/22/2022]
Abstract
Functions of neuronal circuit are fundamentally modulated by its quality and quantity of connections. Assessment of synapse, the basic unit for a neuronal connection, is labor-intensive and time-consuming in conventional culture systems, due to the small size and the spatially random distribution. In the present study, we propose a novel 'synapse compartmentalization' culture system, in which synapses are concentrated at controlled locations. We fabricated a negative dot array pattern by coating the entire surface with poly-l-lysine (PLL) and subsequent microcontact printing of 1) substrates which mask positive charge of PLL (Fc, BSA and laminin), or 2) a chemorepulsive protein (Semaphorin 3F-Fc). By combination of physical and biological features of these repulsive substrates, functional synapses were robustly concentrated in the PLL-coated dots. This synapse compartmentalization chip can be combined with the various high-throughput assay formats based on the synaptic morphology and function. Therefore, this quantifiable and controllable dot array pattern by microcontact printing will be potential useful for bio-chip platforms for the high-density assays used in synapse-related neurobiological studies.
Collapse
Affiliation(s)
- Jae Ryun Ryu
- Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Republic of Korea
| | - Min Jee Jang
- Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Republic of Korea
| | - Youhwa Jo
- Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Republic of Korea
| | - Sunghoon Joo
- Department of Bio and Brain Engineering, KAIST, 291 Daehak-Ro, Yuseong-Gu, Daejeon, 305-701, Republic of Korea
| | - Do Hoon Lee
- School of Mechanical Engineering, Korea University, Seoul, 136-713, Republic of Korea
| | - Byung Yang Lee
- School of Mechanical Engineering, Korea University, Seoul, 136-713, Republic of Korea
| | - Yoonkey Nam
- Department of Bio and Brain Engineering, KAIST, 291 Daehak-Ro, Yuseong-Gu, Daejeon, 305-701, Republic of Korea.
| | - Woong Sun
- Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Republic of Korea.
| |
Collapse
|
43
|
Bannai H, Niwa F, Sherwood MW, Shrivastava AN, Arizono M, Miyamoto A, Sugiura K, Lévi S, Triller A, Mikoshiba K. Bidirectional Control of Synaptic GABAAR Clustering by Glutamate and Calcium. Cell Rep 2015; 13:2768-80. [PMID: 26711343 PMCID: PMC4700050 DOI: 10.1016/j.celrep.2015.12.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 08/13/2015] [Accepted: 11/19/2015] [Indexed: 11/22/2022] Open
Abstract
GABAergic synaptic transmission regulates brain function by establishing the appropriate excitation-inhibition (E/I) balance in neural circuits. The structure and function of GABAergic synapses are sensitive to destabilization by impinging neurotransmitters. However, signaling mechanisms that promote the restorative homeostatic stabilization of GABAergic synapses remain unknown. Here, by quantum dot single-particle tracking, we characterize a signaling pathway that promotes the stability of GABAA receptor (GABAAR) postsynaptic organization. Slow metabotropic glutamate receptor signaling activates IP3 receptor-dependent calcium release and protein kinase C to promote GABAAR clustering and GABAergic transmission. This GABAAR stabilization pathway counteracts the rapid cluster dispersion caused by glutamate-driven NMDA receptor-dependent calcium influx and calcineurin dephosphorylation, including in conditions of pathological glutamate toxicity. These findings show that glutamate activates distinct receptors and spatiotemporal patterns of calcium signaling for opposing control of GABAergic synapses. Bidirectional synaptic control system by glutamate and Ca2+ signaling Stabilization of GABA synapses by mGluR-dependent Ca2+ release from IP3R via PKC Synaptic GABAAR clusters stabilized through regulation of GABAAR lateral diffusion Competition with an NMDAR-dependent Ca2+ pathway driving synaptic destabilization
Collapse
Affiliation(s)
- Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan; Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602, Japan; Nagoya Research Center for Brain & Neural Circuits, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602, Japan; École Normale Supérieure, Institut de Biologie de l'ENS (IBENS), INSERM, CNRS, Ecole Normale Supérieure, PSL Research University, 46 rue d'Ulm, 75005 Paris, France
| | - Fumihiro Niwa
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Mark W Sherwood
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Amulya Nidhi Shrivastava
- École Normale Supérieure, Institut de Biologie de l'ENS (IBENS), INSERM, CNRS, Ecole Normale Supérieure, PSL Research University, 46 rue d'Ulm, 75005 Paris, France
| | - Misa Arizono
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Akitoshi Miyamoto
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Kotomi Sugiura
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Sabine Lévi
- École Normale Supérieure, Institut de Biologie de l'ENS (IBENS), INSERM, CNRS, Ecole Normale Supérieure, PSL Research University, 46 rue d'Ulm, 75005 Paris, France; Institut du Fer à Moulin, INSERM, Unité Mixte de Recherche-S 839, Sorbonne Universités, Université Pierre et Marie Curie, 75005 Paris, France
| | - Antoine Triller
- École Normale Supérieure, Institut de Biologie de l'ENS (IBENS), INSERM, CNRS, Ecole Normale Supérieure, PSL Research University, 46 rue d'Ulm, 75005 Paris, France.
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute (BSI), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
| |
Collapse
|
44
|
Chevy Q, Heubl M, Goutierre M, Backer S, Moutkine I, Eugène E, Bloch-Gallego E, Lévi S, Poncer JC. KCC2 Gates Activity-Driven AMPA Receptor Traffic through Cofilin Phosphorylation. J Neurosci 2015; 35:15772-86. [PMID: 26631461 PMCID: PMC6605455 DOI: 10.1523/jneurosci.1735-15.2015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 09/01/2015] [Accepted: 09/26/2015] [Indexed: 12/31/2022] Open
Abstract
Expression of the neuronal K/Cl transporter KCC2 is tightly regulated throughout development and by both normal and pathological neuronal activity. Changes in KCC2 expression have often been associated with altered chloride homeostasis and GABA signaling. However, recent evidence supports a role of KCC2 in the development and function of glutamatergic synapses through mechanisms that remain poorly understood. Here we show that suppressing KCC2 expression in rat hippocampal neurons precludes long-term potentiation of glutamatergic synapses specifically by preventing activity-driven membrane delivery of AMPA receptors. This effect is independent of KCC2 transporter function and can be accounted for by increased Rac1/PAK- and LIMK-dependent cofilin phosphorylation and actin polymerization in dendritic spines. Our results demonstrate that KCC2 plays a critical role in the regulation of spine actin cytoskeleton and gates long-term plasticity at excitatory synapses in cortical neurons.
Collapse
Affiliation(s)
- Quentin Chevy
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Martin Heubl
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Marie Goutierre
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Stéphanie Backer
- Institut Cochin, Institut National de la Santé et de la Recherche Médicale, U 1016, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8104, Université Paris Descartes, F-75014, Paris, France
| | - Imane Moutkine
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Emmanuel Eugène
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Evelyne Bloch-Gallego
- Institut Cochin, Institut National de la Santé et de la Recherche Médicale, U 1016, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8104, Université Paris Descartes, F-75014, Paris, France
| | - Sabine Lévi
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| | - Jean Christophe Poncer
- Institut National de la Santé et de la Recherche Médicale, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Sorbonne Universités, Université Pierre et Marie Curie Université Paris 06, Unité Mixte de Recherche-S 839, F-75005, Paris, France, Institut du Fer a Moulin, F-75005, Paris, France, and
| |
Collapse
|
45
|
Norkett R, Modi S, Birsa N, Atkin TA, Ivankovic D, Pathania M, Trossbach SV, Korth C, Hirst WD, Kittler JT. DISC1-dependent Regulation of Mitochondrial Dynamics Controls the Morphogenesis of Complex Neuronal Dendrites. J Biol Chem 2015; 291:613-29. [PMID: 26553875 PMCID: PMC4705382 DOI: 10.1074/jbc.m115.699447] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Indexed: 01/09/2023] Open
Abstract
The DISC1 protein is implicated in major mental illnesses including schizophrenia, depression, bipolar disorder, and autism. Aberrant mitochondrial dynamics are also associated with major mental illness. DISC1 plays a role in mitochondrial transport in neuronal axons, but its effects in dendrites have yet to be studied. Further, the mechanisms of this regulation and its role in neuronal development and brain function are poorly understood. Here we have demonstrated that DISC1 couples to the mitochondrial transport and fusion machinery via interaction with the outer mitochondrial membrane GTPase proteins Miro1 and Miro2, the TRAK1 and TRAK2 mitochondrial trafficking adaptors, and the mitochondrial fusion proteins (mitofusins). Using live cell imaging, we show that disruption of the DISC1-Miro-TRAK complex inhibits mitochondrial transport in neurons. We also show that the fusion protein generated from the originally described DISC1 translocation (DISC1-Boymaw) localizes to the mitochondria, where it similarly disrupts mitochondrial dynamics. We also show by super resolution microscopy that DISC1 is localized to endoplasmic reticulum contact sites and that the DISC1-Boymaw fusion protein decreases the endoplasmic reticulum-mitochondria contact area. Moreover, disruption of mitochondrial dynamics by targeting the DISC1-Miro-TRAK complex or upon expression of the DISC1-Boymaw fusion protein impairs the correct development of neuronal dendrites. Thus, DISC1 acts as an important regulator of mitochondrial dynamics in both axons and dendrites to mediate the transport, fusion, and cross-talk of these organelles, and pathological DISC1 isoforms disrupt this critical function leading to abnormal neuronal development.
Collapse
Affiliation(s)
- Rosalind Norkett
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Souvik Modi
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Nicol Birsa
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Talia A Atkin
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Davor Ivankovic
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Manav Pathania
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Svenja V Trossbach
- the Department of Neuropathology, Heinrich Heine University, Moorenstrasse 5, 40225 Dusseldorf, Germany
| | - Carsten Korth
- the Department of Neuropathology, Heinrich Heine University, Moorenstrasse 5, 40225 Dusseldorf, Germany
| | - Warren D Hirst
- the Neuroscience Research Unit, Pfizer, Cambridge, Massachusetts 02139, and
| | - Josef T Kittler
- From the Department of Neuroscience, Physiology, and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom,
| |
Collapse
|
46
|
Tejada-Simon MV. Modulation of actin dynamics by Rac1 to target cognitive function. J Neurochem 2015; 133:767-79. [PMID: 25818528 DOI: 10.1111/jnc.13100] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 03/11/2015] [Accepted: 03/14/2015] [Indexed: 12/14/2022]
Abstract
The small GTPase Rac1 is well known for regulating actin cytoskeleton reorganization in cells. Formation of extensions at the surface of the cell is required for migration and even for cell invasion and metastases. Because an elevated level and hyperactivation of this protein has been associated with metastasis in cancer, direct regulators of Rac1 are currently envisioned as a potential strategy to treat certain cancers. Less research, however, has been done regarding the role of this small GTP-binding protein in brain development, where it has an important role in dendritic spine morphogenesis through the regulation of actin. Alteration of dendritic development and spinogenesis has been often associated with mental disorders. Rac1 is associated with and required for learning and the formation of memories in the brain. Rac1 appears to be dysregulated in certain neurodevelopmental disorders that present all these three alterations: mental retardation, atypical synaptic plasticity and aberrant spine morphology. Thus, to develop novel therapies for rescuing cognitive impairment, a reasonable approach might be to target this protein, Rac1, which plays a pivotal role in directing signals that regulate actin dynamics, which in turn might have an effect in spine cytoarchitecture and synaptic function. It is possible that novel drugs that regulate Rac1 activation and function could modulate actin cytoskeleton and spine dynamics, representing potential candidates to repair intellectual disability in disorders associated with spine abnormalities. Herein, we present a list of the current Rac1 inhibitors that might fulfill this role together with a summary of the latest findings concerning their function as they relate to neuronal studies. While the small GTPase Rac1 is well known for regulating actin cytoskeleton reorganization in different type of cells, it appears to be also required for learning and the formation of memories in the brain. Abnormal regulation of this protein has been associated with cognitive disabilities, atypical synaptic plasticity and abnormal morphology of dendritic spines in certain neurodevelopmental disorders. Thus, modulation of Rac1 activity using novel inhibitors might be a strategy to reestablish cognitive function.
Collapse
Affiliation(s)
- Maria V Tejada-Simon
- Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Houston, Texas, USA.,Department of Biology, University of Houston, Houston, Texas, USA.,Department of Psychology, University of Houston, Houston, Texas, USA.,Biology of Behavior Institute (BoBI), University of Houston, Houston, Texas, USA
| |
Collapse
|
47
|
Regulating Rac in the nervous system: molecular function and disease implication of Rac GEFs and GAPs. BIOMED RESEARCH INTERNATIONAL 2015; 2015:632450. [PMID: 25879033 PMCID: PMC4388020 DOI: 10.1155/2015/632450] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/06/2015] [Indexed: 12/11/2022]
Abstract
Rho family GTPases, including RhoA, Rac1, and Cdc42 as the most studied members, are master regulators of actin cytoskeletal organization. Rho GTPases control various aspects of the nervous system and are associated with a number of neuropsychiatric and neurodegenerative diseases. The activity of Rho GTPases is controlled by two families of regulators, guanine nucleotide exchange factors (GEFs) as the activators and GTPase-activating proteins (GAPs) as the inhibitors. Through coordinated regulation by GEFs and GAPs, Rho GTPases act as converging signaling molecules that convey different upstream signals in the nervous system. So far, more than 70 members of either GEFs or GAPs of Rho GTPases have been identified in mammals, but only a small subset of them have well-known functions. Thus, characterization of important GEFs and GAPs in the nervous system is crucial for the understanding of spatiotemporal dynamics of Rho GTPase activity in different neuronal functions. In this review, we summarize the current understanding of GEFs and GAPs for Rac1, with emphasis on the molecular function and disease implication of these regulators in the nervous system.
Collapse
|
48
|
Hong ST, Mah W. A Critical Role of GIT1 in Vertebrate and Invertebrate Brain Development. Exp Neurobiol 2015; 24:8-16. [PMID: 25792865 PMCID: PMC4363336 DOI: 10.5607/en.2015.24.1.8] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 02/14/2015] [Accepted: 02/14/2015] [Indexed: 11/20/2022] Open
Abstract
GIT1, a multifunctional signaling adaptor protein, is implicated in the development of dendritic spines and neuronal synapses. GIT1 forms a signaling complex with PIX, RAC, and PAK proteins that is known to play important roles in brain development. Here we found that Git1-knockout (Git1-/-) mice show a microcephaly-like small brain phenotype, which appears to be caused by reduced neuronal size rather than number. Git1-/- mice also show decreased dendritic spine number without morphological alterations in the hippocampus. Behaviorally, Git1-/- mice show impaired motor coordination and learning and memory. In addition, adult dGit Drosophila mutants show decreased brain size and abnormal morphology of the mushroom body. These results suggest that GIT1 is important for brain development in both rodents and flies.
Collapse
Affiliation(s)
- Sung-Tae Hong
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea
| | - Won Mah
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. ; Department of Anatomy and Neurobiology, School of Dentistry, Kyungpook National University, Daegu, Korea
| |
Collapse
|