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Edward W Vogel, Fatima N Morales, David F Meaney, Cameron R Bass, Barclay Morrison
Due to recent military conflicts and terrorist attacks, blast-induced traumatic brain injury (bTBI) presents a health concern for military and civilian personnel alike. Although secondary blast (penetrating injury) and tertiary blast (inertia-driven brain deformation) are known to be injurious, the effects of primary blast caused by the supersonic shock wave interacting with the skull and brain remain debated. Our group previously reported that in vitro primary blast exposure reduced long-term potentiation (LTP), the electrophysiological correlate of learning and memory, in rat organotypic hippocampal slice cultures (OHSCs) and that primary blast affects key proteins governing LTP...
March 31, 2017: Experimental Neurology
Caleigh M Azumaya, Emily L Days, Paige N Vinson, Shaun Stauffer, Gary Sulikowski, C David Weaver, Terunaga Nakagawa
AMPA receptors (AMPAR) are ligand gated ion channels critical for synaptic transmission and plasticity. Their dysfunction is implicated in a variety of psychiatric and neurological diseases ranging from major depressive disorder to amyotrophic lateral sclerosis. Attempting to potentiate or depress AMPAR activity is an inherently difficult balancing act between effective treatments and debilitating side effects. A newly explored strategy to target subsets of AMPARs in the central nervous system is to identify compounds that affect specific AMPAR-auxiliary subunit complexes...
2017: PloS One
Mengping Wei, Moye Jia, Jian Zhang, Lulu Yu, Yunzhi Zhao, Yingqi Chen, Yimeng Ma, Wei Zhang, Yun S Shi, Chen Zhang
The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) are major excitatory receptors that mediate fast neurotransmission in the mammalian brain. The surface expression of functional AMPARs is crucial for synaptic transmission and plasticity. AMPAR auxiliary subunits control the biosynthesis, membrane trafficking, and synaptic targeting of AMPARs. Our previous report showed that α/β-hydrolase domain-containing 6 (ABHD6), an auxiliary subunit for AMPARs, suppresses the membrane delivery and function of GluA1-containing receptors in both heterologous cells and neurons...
2017: Frontiers in Molecular Neuroscience
Anat Ben-Yaacov, Moshe Gillor, Tomer Haham, Alon Parsai, Mohammad Qneibi, Yael Stern-Bach
AMPA receptors (AMPARs) mediate the majority of fast excitatory transmission in the brain and critically contribute to synaptic plasticity and pathology. AMPAR trafficking and gating are tightly controlled by auxiliary transmembrane AMPAR regulatory proteins (TARPs). Here, using systematic domain swaps with the TARP-insensitive kainate receptor GluK2, we show that AMPAR interaction with the prototypical TARP stargazin/γ2 primarily involves the AMPAR membrane domains M1 and M4 of neighboring subunits, initiated or stabilized by the AMPAR C-tail, and that these interactions are sufficient to enable full receptor modulation...
February 17, 2017: Neuron
Z Barad, D R Grattan, B Leitch
In the stargazer mouse model of absence epilepsy, altered corticothalamic excitation of reticular thalamic nucleus (RTN) neurons has been suggested to contribute to abnormal synchronicity in the corticothalamic-thalamocortical circuit, leading to spike-wave discharges, the hallmark of absence seizures. AMPA receptor expression and function are decreased in stargazer RTN, due to a mutation of AMPAR auxiliary subunit stargazin. It is unresolved and debated, however, if decreased excitation of RTN is compatible with epileptogenesis...
February 21, 2017: Scientific Reports
Pengcheng Yin, Hao Xu, Qi Wang, Jiayue Wang, Liang Yin, Meichen Xu, Zhenyang Xie, Wenzhao Liu, Xiaohua Cao
Behavioral flexibility is in close proximity to dentate gyrus (DG) function and long-term depression (LTD), but the role of DG LTD in behavioral flexibility has hitherto been unexplored. Although the functions of alpha-Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) have been studied extensively, the role of βCaMKII, a constituent of the CaMKII holoenzyme, in LTD and behavioral flexibility has not been investigated in vivo. Here using the βCaMKII-F90G transgenic (TG) mice, in which the inducible and reversible overexpression of βCaMKII is restricted to dentate gyrus (DG), we found that TG mice exhibited defective behavioral flexibility in two reversal tasks and seriously impaired N-methyl-d-aspartic acid receptor (NMDAR)-dependent LTD in DG medial perforant path (MPP)...
December 16, 2016: Neuropharmacology
Nadia Kafui Adotevi, Beulah Leitch
Absence seizures arise from disturbances within the corticothalamocortical network, however the precise cellular and molecular mechanisms underlying seizure generation arising from different genetic backgrounds are not fully understood. While recent experimental evidence suggests that changes in inhibitory microcircuits in the cortex may contribute to generation of the hallmark spike-wave discharges, it is still unclear if altered cortical inhibition is a result of interneuron dysfunction due to compromised glutamatergic excitation and/or changes in cortical interneuron number...
December 17, 2016: Neuroscience
Sana A Shaikh, Drew M Dolino, Garam Lee, Sudeshna Chatterjee, David M MacLean, Charlotte Flatebo, Christy F Landes, Vasanthi Jayaraman
Fast excitatory synaptic signaling in the mammalian brain is mediated by AMPA-type ionotropic glutamate receptors. In neurons, AMPA receptors co-assemble with auxiliary proteins, such as stargazin, which can markedly alter receptor trafficking and gating. Here, we used luminescence resonance energy transfer measurements to map distances between the full-length, functional AMPA receptor and stargazin expressed in HEK293 cells and to determine the ensemble structural changes in the receptor due to stargazin. In addition, we used single-molecule fluorescence resonance energy transfer to study the structural and conformational distribution of the receptor and how this distribution is affected by stargazin...
October 4, 2016: Cell Reports
Edward W Vogel, Steve H Rwema, David F Meaney, Cameron R Dale Bass, Barclay Morrison
Blast-induced traumatic brain injury (bTBI) is a major threat to United States service members in military conflicts worldwide. The effects of primary blast, caused by the supersonic shockwave interacting with the skull and brain, remain unclear. Our group has previously reported that in vitro primary blast exposure can reduce long-term potentiation (LTP), the electrophysiological correlate of learning and memory, in rat organotypic hippocampal slice cultures (OHSCs) without significant changes to cell viability or basal, evoked neuronal function...
March 1, 2017: Journal of Neurotrauma
Edward C Twomey, Maria V Yelshanskaya, Robert A Grassucci, Joachim Frank, Alexander I Sobolevsky
AMPA-subtype ionotropic glutamate receptors (AMPARs) mediate fast excitatory neurotransmission and contribute to high cognitive processes such as learning and memory. In the brain, AMPAR trafficking, gating, and pharmacology is tightly controlled by transmembrane AMPAR regulatory proteins (TARPs). Here, we used cryo-electron microscopy to elucidate the structural basis of AMPAR regulation by one of these auxiliary proteins, TARP γ2, or stargazin (STZ). Our structures illuminate the variable interaction stoichiometry of the AMPAR-TARP complex, with one or two TARP molecules binding one tetrameric AMPAR...
July 1, 2016: Science
Mengping Wei, Jian Zhang, Moye Jia, Chaojuan Yang, Yunlong Pan, Shuaiqi Li, Yiwen Luo, Junyuan Zheng, Jianguo Ji, Jianguo Chen, Xinli Hu, Jingwei Xiong, Yun Shi, Chen Zhang
In the brain, AMPA-type glutamate receptors are major postsynaptic receptors at excitatory synapses that mediate fast neurotransmission and synaptic plasticity. α/β-Hydrolase domain-containing 6 (ABHD6), a monoacylglycerol lipase, was previously found to be a component of AMPA receptor macromolecular complexes, but its physiological significance in the function of AMPA receptors (AMPARs) has remained unclear. The present study shows that overexpression of ABHD6 in neurons drastically reduced excitatory neurotransmission mediated by AMPA but not by NMDA receptors at excitatory synapses...
May 10, 2016: Proceedings of the National Academy of Sciences of the United States of America
Alex G Lee, Roxanne Capanzana, Jacqueline Brockhurst, Michelle Y Cheng, Christine L Buckmaster, Devin Absher, Alan F Schatzberg, David M Lyons
Intermittent mildly stressful situations provide opportunities to learn, practice, and improve coping with gains in subsequent emotion regulation. Here we investigate the effects of learning to cope with stress on anterior cingulate cortex gene expression in monkeys and mice. Anterior cingulate cortex is involved in learning, memory, cognitive control, and emotion regulation. Monkeys and mice were randomized to either stress coping or no-stress treatment conditions. Profiles of gene expression were acquired with HumanHT-12v4...
May 2016: Neurobiology of Learning and Memory
Sarah K Coleman, Ying Hou, Marina Willibald, Artur Semenov, Tommi Möykkynen, Kari Keinänen
AMPA receptors are glutamate-gated cation channels assembled from GluA1-4 subunits and have properties that are strongly dependent on the subunit composition. The subunits have different propensities to form homomeric or various heteromeric receptors expressed on cell surface, but the underlying mechanisms are still poorly understood. Here, we examined the biochemical basis for the poor ability of GluA3 subunits to form homomeric receptors, linked previously to two amino acid residues, Tyr-454 and Arg-461, in its ligand binding domain (LBD)...
April 15, 2016: Journal of Biological Chemistry
Thomas P McGee, Cécile Bats, Mark Farrant, Stuart G Cull-Candy
UNLABELLED: AMPA-type glutamate receptors are ligand-gated cation channels responsible for a majority of the fast excitatory synaptic transmission in the brain. Their behavior and calcium permeability depends critically on their subunit composition and the identity of associated auxiliary proteins. Calcium-permeable AMPA receptors (CP-AMPARs) contribute to various forms of synaptic plasticity, and their dysfunction underlies a number of serious neurological conditions. For CP-AMPARs, the prototypical transmembrane AMPAR regulatory protein stargazin, which acts as an auxiliary subunit, enhances receptor function by increasing single-channel conductance, slowing channel gating, increasing calcium permeability, and relieving the voltage-dependent block by endogenous intracellular polyamines...
December 9, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Birbickram Roy, Kazi T Ahmed, Marcus E Cunningham, Jannatul Ferdous, Rajarshi Mukherjee, Wang Zheng, Xing-Zhen Chen, Declan W Ali
Fast excitatory synaptic transmission in the CNS is mediated by the neurotransmitter glutamate, binding to and activating AMPA receptors (AMPARs). AMPARs are known to interact with auxiliary proteins that modulate their behavior. One such family of proteins is the transmembrane AMPA receptor-related proteins, known as TARPs. Little is known about the role of TARPs during development, or about their function in non-mammalian organisms. Here we report the presence of TARPs, specifically the prototypical TARP, stargazin, in developing zebrafish...
May 2016: Developmental Neurobiology
Wenchi Zhang, Jing Wu, Matthew D Ward, Sunggu Yang, Yang-An Chuang, Meifang Xiao, Ruojing Li, Daniel J Leahy, Paul F Worley
Arc is a cellular immediate-early gene (IEG) that functions at excitatory synapses and is required for learning and memory. We report crystal structures of Arc subdomains that form a bi-lobar architecture remarkably similar to the capsid domain of human immunodeficiency virus (HIV) gag protein. Analysis indicates Arc originated from the Ty3/Gypsy retrotransposon family and was "domesticated" in higher vertebrates for synaptic functions. The Arc N-terminal lobe evolved a unique hydrophobic pocket that mediates intermolecular binding with synaptic proteins as resolved in complexes with TARPγ2 (Stargazin) and CaMKII peptides and is essential for Arc's synaptic function...
April 22, 2015: Neuron
Anne-Sophie Hafner, Andrew C Penn, Dolors Grillo-Bosch, Natacha Retailleau, Christel Poujol, Amandine Philippat, Françoise Coussen, Matthieu Sainlos, Patricio Opazo, Daniel Choquet
PSD-95 is a prominent organizer of the postsynaptic density (PSD) that can present a filamentous orientation perpendicular to the plasma membrane. Interactions between PSD-95 and transmembrane proteins might be particularly sensitive to this orientation, as "long" cytoplasmic tails might be required to reach deeper PSD-95 domains. Extension/retraction of transmembrane protein C-tails offer a new way of regulating binding to PSD-95. Using stargazin as a model, we found that enhancing the apparent length of stargazin C-tail through phosphorylation or by an artificial linker was sufficient to potentiate binding to PSD-95, AMPAR anchoring, and synaptic transmission...
April 22, 2015: Neuron
Mark Rigby, Stuart G Cull-Candy, Mark Farrant
Presynaptic ionotropic glutamate receptors (iGluRs) play important roles in the control of synaptogenesis and neurotransmitter release, yet their regulation is poorly understood. In particular, the contribution of transmembrane auxiliary proteins, which profoundly shape the trafficking and gating of somatodendritic iGluRs, is unknown. Here we examined the influence of transmembrane AMPAR regulatory proteins (TARPs) on presynaptic AMPARs in cerebellar molecular layer interneurons (MLIs). 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a partial agonist at TARP-associated AMPARs, enhanced spontaneous GABA release in wild-type mice but not in stargazer mice that lack the prototypical TARP stargazin (γ-2)...
March 11, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Audrey Constals, Andrew C Penn, Benjamin Compans, Estelle Toulmé, Amandine Phillipat, Sébastien Marais, Natacha Retailleau, Anne-Sophie Hafner, Françoise Coussen, Eric Hosy, Daniel Choquet
Short-term plasticity of AMPAR currents during high-frequency stimulation depends not only on presynaptic transmitter release and postsynaptic AMPAR recovery from desensitization, but also on fast AMPAR diffusion. How AMPAR diffusion within the synapse regulates synaptic transmission on the millisecond scale remains mysterious. Using single-molecule tracking, we found that, upon glutamate binding, synaptic AMPAR diffuse faster. Using AMPAR stabilized in different conformational states by point mutations and pharmacology, we show that desensitized receptors bind less stargazin and are less stabilized at the synapse than receptors in opened or closed-resting states...
February 18, 2015: Neuron
Maya Yamazaki, Claire E Le Pichon, Alexander C Jackson, Manuel Cerpas, Kenji Sakimura, Kimberly Scearce-Levie, Roger A Nicoll
Transmembrane AMPA receptor regulatory proteins (TARPs) play an essential role in excitatory synaptic transmission throughout the central nervous system (CNS) and exhibit subtype-specific effects on AMPA receptor (AMPAR) trafficking, gating, and pharmacology. The function of TARPs has largely been determined through work on canonical type I TARPs such as stargazin (TARP γ-2), absent in the ataxic stargazer mouse. Little is known about the function of atypical type II TARPs, such as TARP γ-7, which exhibits variable effects on AMPAR function...
January 27, 2015: Proceedings of the National Academy of Sciences of the United States of America
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