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Ward G Walkup, Tara L Mastro, Leslie T Schenker, Jost Vielmetter, Rebecca Hu, Ariella Iancu, Meera Reghunathan, Barry Dylan Bannon, Mary B Kennedy
No abstract text is available yet for this article.
October 19, 2016: ELife
Ward G Walkup, Tara L Mastro, Leslie T Schenker, Jost Vielmetter, Rebecca Hu, Ariella Iancu, Meera Reghunathan, Barry Dylan Bannon, Mary B Kennedy
SynGAP is a Ras/Rap GTPase-activating protein (GAP) that is a major constituent of postsynaptic densities (PSDs) from mammalian forebrain. Its α1 isoform binds to all three PDZ (PSD-95, Discs-large, ZO-1) domains of PSD-95, the principal PSD scaffold, and can occupy as many as 15% of these PDZ domains. We present evidence that synGAP-α1 regulates the composition of the PSD by restricting binding to the PDZ domains of PSD-95. We show that phosphorylation by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and Polo-like kinase-2 (PLK2) decreases its affinity for the PDZ domains by several fold, which would free PDZ domains for occupancy by other proteins...
September 13, 2016: ELife
Menglong Zeng, Yuan Shang, Yoichi Araki, Tingfeng Guo, Richard L Huganir, Mingjie Zhang
Postsynaptic densities (PSDs) are membrane semi-enclosed, submicron protein-enriched cellular compartments beneath postsynaptic membranes, which constantly exchange their components with bulk aqueous cytoplasm in synaptic spines. Formation and activity-dependent modulation of PSDs is considered as one of the most basic molecular events governing synaptic plasticity in the nervous system. In this study, we discover that SynGAP, one of the most abundant PSD proteins and a Ras/Rap GTPase activator, forms a homo-trimer and binds to multiple copies of PSD-95...
August 25, 2016: Cell
Jingrui Xing, Hiroki Kimura, Chenyao Wang, Kanako Ishizuka, Itaru Kushima, Yuko Arioka, Akira Yoshimi, Yukako Nakamura, Tomoko Shiino, Tomoko Oya-Ito, Yuto Takasaki, Yota Uno, Takashi Okada, Tetsuya Iidaka, Branko Aleksic, Daisuke Mori, Norio Ozaki
PSD-95 associated PSD proteins play a critical role in regulating the density and activity of glutamate receptors. Numerous previous studies have shown an association between the genes that encode these proteins and schizophrenia (SZ) and autism spectrum disorders (ASD), which share a substantial portion of genetic risks. We sequenced the protein-encoding regions of DLG1, DLG2, DLG4, DLGAP1, DLGAP2, and SynGAP in 562 cases (370 SZ and 192 ASD patients) on the Ion PGM platform. We detected 26 rare (minor allele frequency <1%), non-synonymous mutations, and conducted silico functional analysis and pedigree analysis when possible...
2016: Scientific Reports
Maria del Mar Masdeu, Beatriz G Armendáriz, Eduardo Soriano, Jesús Mariano Ureña, Ferran Burgaya
The regulation of focal adhesion kinase (FAK) involves phosphorylation and multiple interactions with other signaling proteins. Some of these pathways are relevant for nervous system functions such as branching, axonal guidance, and plasticity. In this study, we screened mouse brain to identify FAK-interactive proteins and phosphorylatable residues as a first step to address the neuronal functions of this kinase. Using mass spectrometry analysis, we identified new phosphorylated sites (Thr 952, Thr 1048, and Ser 1049), which lie in the FAT domain; and putative new partners for FAK, which include cytoskeletal proteins such as drebrin and MAP 6, adhesion regulators such as neurabin-2 and plakophilin 1, and synapse-associated proteins such as SynGAP and a NMDA receptor subunit...
July 2016: Biochimica et Biophysica Acta
Rong Rong, Hui Yang, Liangqun Rong, Xiue Wei, Qingjie Li, Xiaomei Liu, Hong Gao, Yun Xu, Qingxiu Zhang
Postsynaptic density protein-93 (PSD-93) is enriched in the postsynaptic density and is involved in N-methyl-d-aspartate receptor (NMDAR) triggered neurotoxicity through PSD-93/NMDAR/nNOS signaling pathway. In the present study, we found that PSD-93 deficiency reduced infarcted volume and neurological deficits induced by transient middle cerebral artery occlusion (tMCAO) in the mice. To identify novel targets of PSD-93 related neurotoxicity, we applied isobaric tags for relative and absolute quantitative (iTRAQ) labeling and combined this labeling with on-line two-dimensional LC/MS/MS technology to elucidate the changes in protein expression in PSD-93 knockout mice following tMCAO...
March 2016: Neurotoxicology
See-Ying Tam, Jennifer N Lilla, Ching-Cheng Chen, Janet Kalesnikoff, Mindy Tsai
Nerve growth factor (NGF) binds to its cognate receptor TrkA and induces neuronal differentiation by activating distinct downstream signal transduction events. RabGEF1 (also known as Rabex-5) is a guanine nucleotide exchange factor for Rab5, which regulates early endosome fusion and vesicular trafficking in endocytic pathways. Here, we used the antisense (AS) expression approach to induce an NGF-dependent sustained knockdown of RabGEF1 protein expression in stable PC12 transfectants. We show that RabGEF1 is a negative regulator of NGF-induced neurite outgrowth and modulates other cellular and signaling processes that are activated by the interaction of NGF with TrkA receptors, such as cell cycle progression, cessation of proliferation, and activation of NGF-mediated downstream signaling responses...
2015: PloS One
Stephanie A Barnes, Lasani S Wijetunge, Adam D Jackson, Danai Katsanevaki, Emily K Osterweil, Noboru H Komiyama, Seth G N Grant, Mark F Bear, U Valentin Nägerl, Peter C Kind, David J A Wyllie
UNLABELLED: Previous studies have hypothesized that diverse genetic causes of intellectual disability (ID) and autism spectrum disorders (ASDs) converge on common cellular pathways. Testing this hypothesis requires detailed phenotypic analyses of animal models with genetic mutations that accurately reflect those seen in the human condition (i.e., have structural validity) and which produce phenotypes that mirror ID/ASDs (i.e., have face validity). We show that SynGAP haploinsufficiency, which causes ID with co-occurring ASD in humans, mimics and occludes the synaptic pathophysiology associated with deletion of the Fmr1 gene...
November 11, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Sandra Giovanoli, Ulrike Weber-Stadlbauer, Manfred Schedlowski, Urs Meyer, Harald Engler
Prenatal exposure to infectious or inflammatory insults can increase the risk of developing neuropsychiatric disorder in later life, including schizophrenia, bipolar disorder, and autism. These brain disorders are also characterized by pre- and postsynaptic deficits. Using a well-established mouse model of maternal exposure to the viral mimetic polyriboinosinic-polyribocytidilic acid [poly(I:C)], we examined whether prenatal immune activation might cause synaptic deficits in the hippocampal formation of pubescent and adult offspring...
July 2016: Brain, Behavior, and Immunity
Ayse Dosemeci, Dana Toy, Thomas S Reese, Jung-Hwa Tao-Cheng
AIDA-1 is highly enriched in postsynaptic density (PSD) fractions and is considered a major component of the PSD complex. In the present study, immunogold electron microscopy was applied to determine localization as well as the activity-induced redistribution of AIDA-1 at the PSD using two antibodies that recognize two different epitopes. In cultured rat hippocampal neurons under basal conditions, immunogold label for AIDA-1 is mostly located within the dense core of the PSD, with a median distance of ~30 nm from the postsynaptic membrane...
2015: PloS One
Juan F Codocedo, Carla Montecinos-Oliva, Nibaldo C Inestrosa
Wnt-5a is a synaptogenic factor that modulates glutamatergic synapses and generates neuroprotection against Aβ oligomers. It is known that Wnt-5a plays a key role in the adult nervous system and synaptic plasticity. Emerging evidence indicates that miRNAs are actively involved in the regulation of synaptic plasticity. Recently, we showed that Wnt-5a is able to control the expression of several miRNAs including miR-101b, which has been extensively studied in carcinogenesis. However, its role in brain is just beginning to be explored...
2015: Frontiers in Cellular Neuroscience
Michael J Parker, Alan E Fryer, Deborah J Shears, Katherine L Lachlan, Shane A McKee, Alex C Magee, Shehla Mohammed, Pradeep C Vasudevan, Soo-Mi Park, Valérie Benoit, Damien Lederer, Isabelle Maystadt, Ddd Study, David R FitzPatrick
De novo mutations (DNM) in SYNGAP1, encoding Ras/Rap GTPase-activating protein SynGAP, have been reported in individuals with nonsyndromic intellectual disability (ID). We identified 10 previously unreported individuals with SYNGAP1 DNM; seven via the Deciphering Developmental Disorders (DDD) Study, one through clinical analysis for copy number variation and the remaining two (monozygotic twins) via a research multi-gene panel analysis. Seven of the nine heterozygous mutations are likely to result in loss-of-function (3 nonsense; 3 frameshift; 1 whole gene deletion)...
October 2015: American Journal of Medical Genetics. Part A
Ryunosuke Muro, Takeshi Nitta, Toshiyuki Okada, Hitoshi Ideta, Takeshi Tsubata, Harumi Suzuki
The Ras-mitogen-activated protein kinase (MAPK) pathway is crucial for T cell receptor (TCR) signaling in the development and function of T cells. The significance of various modulators of the Ras-MAPK pathway in T cells, however, remains to be fully understood. Ras-activating protein-like 3 (Rasal3) is an uncharacterized member of the SynGAP family that contains a conserved Ras GTPase-activating protein (GAP) domain, and is predominantly expressed in the T cell lineage. In the current study, we investigated the function and physiological roles of Rasal3...
2015: PloS One
Yoichi Araki, Menglong Zeng, Mingjie Zhang, Richard L Huganir
SynGAP is a Ras-GTPase activating protein highly enriched at excitatory synapses in the brain. Previous studies have shown that CaMKII and the RAS-ERK pathway are critical for several forms of synaptic plasticity including LTP. NMDA receptor-dependent calcium influx has been shown to regulate the RAS-ERK pathway and downstream events that result in AMPA receptor synaptic accumulation, spine enlargement, and synaptic strengthening during LTP. However, the cellular mechanisms whereby calcium influx and CaMKII control Ras activity remain elusive...
January 7, 2015: Neuron
Ward G Walkup, Lorraine Washburn, Michael J Sweredoski, Holly J Carlisle, Robert L Graham, Sonja Hess, Mary B Kennedy
synGAP is a neuron-specific Ras and Rap GTPase-activating protein (GAP) found in high concentrations in the postsynaptic density (PSD) fraction from the mammalian forebrain. We have previously shown that, in situ in the PSD fraction or in recombinant form in Sf9 cell membranes, synGAP is phosphorylated by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), another prominent component of the PSD. Here, we show that recombinant synGAP (r-synGAP), lacking 102 residues at the N terminus, can be purified in soluble form and is phosphorylated by cyclin-dependent kinase 5 (CDK5) as well as by CaMKII...
February 20, 2015: Journal of Biological Chemistry
Xin-long Huo, Jing-jing Min, Cai-yu Pan, Cui-cui Zhao, Lu-lu Pan, Fei-fei Gui, Lu Jin, Xiao-tong Wang
BACKGROUND: Chronic intermittent hypoxia-hypercapnia (CIHH) exposure leads to learnning and memory deficits in rats. Overactivation of N-methyl-D-aspartate receptors(NMDARs) can lead to the death of neurons through a process termed excitotoxicity, which is involved in CIHH-induced cognitive deficits. Excessively activated NR2B (GluN2B)-containing NMDARs was reported as the main cause of excitotoxicity. The ERK1/2 (extracellular signal-regulated kinase 1/2) signaling cascade acts as a key component in NMDARs-dependent neuronal plasticity and survival...
2014: PloS One
Chih-Chieh Wang, Richard G Held, Benjamin J Hall
Disrupting the balance between excitatory and inhibitory neurotransmission in the developing brain has been causally linked with intellectual disability (ID) and autism spectrum disorders (ASD). Excitatory synapse strength is regulated in the central nervous system by controlling the number of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). De novo genetic mutations of the synaptic GTPase-activating protein (SynGAP) are associated with ID and ASD. SynGAP is enriched at excitatory synapses and genetic suppression of SynGAP increases excitatory synaptic strength...
2013: PloS One
Yijung Yang, Jung-Hwa Tao-Cheng, K Ulrich Bayer, Thomas S Reese, Ayse Dosemeci
SynGAP, a protein abundant at the postsynaptic density (PSD) of glutamatergic neurons, is known to modulate synaptic strength by regulating the incorporation of AMPA receptors at the synapse. Two isoforms of SynGAP, α1 and α2, which differ in their C-termini, have opposing effects on synaptic strength. In the present study, antibodies specific for SynGAP-α1 and SynGAP-α2 are used to compare the distribution patterns of the two isoforms at the postsynaptic density (PSD) under basal and excitatory conditions...
2013: PloS One
Jean-Bernard Dietrich
The MEF2 (myocyte enhancer factor 2) family of transcription factors is composed of four distinct vertebrate genes. These factors were first identified in muscle but are also present in brain. MEF2 is involved in neuronal survival and is able to regulate the growth and pruning of neurons in response to stimulation. Dendrite remodelling is under the control of genes that MEF2 can turn on or off and some of its target genes have been identified. Among them are immediate-early genes such as C-JUN and NUR77 and neuronal-activity-regulated genes such as ARC, SYNGAP, HOMER1A and BDNF...
May 2013: Cell and Tissue Research
James P Clement, Massimiliano Aceti, Thomas K Creson, Emin D Ozkan, Yulin Shi, Nicholas J Reish, Antoine G Almonte, Brooke H Miller, Brian J Wiltgen, Courtney A Miller, Xiangmin Xu, Gavin Rumbaugh
Mutations that cause intellectual disability (ID) and autism spectrum disorder (ASD) are commonly found in genes that encode for synaptic proteins. However, it remains unclear how mutations that disrupt synapse function impact intellectual ability. In the SYNGAP1 mouse model of ID/ASD, we found that dendritic spine synapses develop prematurely during the early postnatal period. Premature spine maturation dramatically enhanced excitability in the developing hippocampus, which corresponded with the emergence of behavioral abnormalities...
November 9, 2012: Cell
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