Lentiviral Expression of Rabies Virus Glycoprotein in the Rat Hippocampus Strengthens Synaptic Plasticity (original) (raw)
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Rabies virus glycoprotein enhances spatial memory via the PDZ binding motif
Journal of NeuroVirology
Rabies is a life-threatening viral infection of the brain. Rabies virus (RABV) merely infects excitable cells including neurons provoking drastic behaviors including negative emotional memories. RABV glycoprotein (RVG) plays a critical role in RABV pathogenesis. RVG interacts with various cytoplasmic PDZ (PSD-95/Dlg/ZO-1) containing proteins through its PDZ binding motif (PBM). PTZ domains have crucial role in formation and function of signal transduction. Hippocampus is one of the cerebral regions that contains high load of viral antigens. We examined impact of RVG expression in the dorsal hippocampus on aversive as well as spatial learning and memory performance in rats. Two μl of the lentiviral vector (~10 8 T.U. /ml) encoding RVG or ∆RVG (deleted PBM) genomes was microinjected into the hippocampal CA1. After one week, rat's brain was cross-sectioned and RVG/∆RVG-expressing neuronal cells were confirmed by fluorescent microscopy. Passive avoidance and spatial learning and memory were assessed in rats by Shuttle box and Morris water maze (MWM). In the shuttle box, both RVG and ∆RVG decreased the time spent in the dark compartment compared to control (p<0.05). In MWM, RVG and ∆RVG did not affect the acquisition of spatial task. RVG-expressing rats reached the platform position in the probe test sooner than control and ∆RVG groups (p<0.05). Rats expressing ∆RVG significantly swam farther from the hidden platform than RVG group (p<0.05). Our data indicate RVG expression in the hippocampus strengthens aversive and spatial learning and memory performance. The boosting effect on spatial but not avoidance memory is mediated through PBM.
Progress in Biophysics and Molecular Biology, 2015
a b s t r a c t PDZ (PSD-95/Dlg/ZO-1) domains play a major role in neuronal homeostasis in which they act as scaffold domains regulating cellular trafficking, self-association and catalytic activity of essential proteins such as kinases and phosphatases. Because of their central role in cell signaling, cellular PDZ-containing proteins are preferential targets of viruses to hijack cellular function to their advantage. Here, we describe how the viral G protein of the rabies virus specifically targets the PDZ domain of neuronal enzymes during viral infection. By disrupting the complexes formed by cellular enzymes and their ligands, the virus triggers drastic effect on cell signaling and commitment of the cell to either survival (virulent strains) or death (vaccinal strains). We provide structural and biological evidences that the viral proteins act as competitors endowed with specificity and affinity in an essential cellular process by mimicking PDZ binding motif of cellular partners. Disruption of critical endogenous proteineprotein interactions by viral protein drastically alters intracellular protein trafficking and catalytic activity of cellular proteins that control cell homeostasis. This work opens up many perspectives to mimic viral sequences and developing innovative therapies to manipulate cellular homeostasis. Abbreviations: CytoG, C-terminal cytoplasmic tail of G protein; MAST2, microtubule-associated serine and threonine kinase 2; PBM, PDZ binding motif; PDZ, PSD-95/Dlg/ZO-1; PSD, post-synaptic density; PTEN, phosphatase and tensin homolog deleted on chromosome 10; PTP, Protein tyrosine phosphatase; RABV, Rabies virus; SliM, small linear interaction motifs. * Corresponding author. Unit e de RMN des biomol ecules, Institut Pasteur-URA 3528 CNRS, 28, rue du Dr Roux, 75724 Paris cedex 15, France. Tel.: þ33 (0)1 45 68 88 72; fax: þ33 (0)1 45 68 89 29.
Neuron, 2006
RGS2, one of the small members of the regulator of G protein signaling (RGS) family, is highly expressed in brain and regulates G(i/o) as well as G(q)-coupled receptor pathways. RGS2 modulates anxiety, aggression, and blood pressure in mice, suggesting that RGS2 regulates synaptic circuits underlying animal physiology and behavior. How RGS2 in brain influences synaptic activity is unknown. We therefore analyzed the synaptic function of RGS2 in hippocampal neurons by comparing electrophysiological recordings from RGS2 knockout and wild-type mice. Our study provides a general mechanism of the action of the RGS family containing RGS2 by demonstrating that RGS2 increases synaptic vesicle release by downregulating the G(i/o)-mediated presynaptic Ca(2+) channel inhibition and therefore provides an explanation of how regulation of RGS2 expression can modulate the function of neuronal circuits underlying behavior.
The Role of the Ras Guanyl-Nucleotide Exchange Factor Rasgrp1 in Synaptic Transmission
Official Symbol Name Other designations, notes Calb1 Calbindin D-28K, calbindin D28 Calb2 Calretinin, Calbindin2 CR Camk2a calcium/calmodulin-dependent protein kinase II alpha CamkII subunit alpha Canx Calnexin Cnx Creb1 cAMP responsive element binding protein 1 Dab2ip disabled homolog 2 (Drosophila) interacting protein Dgkz diacylglycerol kinase zeta Diap1 diaphanous homolog 1 Dia1 Dlg2 disks large homolog 2 PSD-93, Psd93, Chapsyn-110 Dlg4 disks large homolog 4 PSD-95, Psd95 Eea1 early endosome antigen 1 Egf Epidermal growth factor Gad1 glutamic acid decarboxylase 1 EP10, GAD25, GAD44, GAD67 Gad2 glutamic acid decarboxylase 2 GAD65 Golgb1 Giantin, golgi autoantigen, golgin subfamily b, macrogolgin 1 Gm6840 Grb2 growth factor receptor-bound protein 2 Gria1 glutamate receptor, ionotropic, AMPA1 (alpha 1) GluR1, GluA1, GluRA Gria2 glutamate receptor, ionotropic, AMPA2 (alpha 2) GluR2, GluA2, GluR-B, Glur-Diese Studie enthält die ersten Beweise für eine spezifische neuronale Funktion von Rasgrp1. Sie zeigt, dass Rasgrp1 selektiv die postsynaptische Sensitivität an glutamatergen Synapsen reguliert. Diese Studie zeigt, dass die selektive Veränderung der Regulation von Ras eine hilfreiche Methode ist, um die vielfältigen Effekte der Ras Signaltransduktion in Neuronen verstehen zu können. represent the postsynapse. Upon binding of Glutamate, the receptors open and allow Sodium to enter the cell. Upon this influx of cations, the cell depolarizes locally. This electrical signal propagates as the depolarization passively spreads through the dendrites. Spine shape, dendrite caliber and branching influence signal propagation as it travels to the soma. In the soma, final integration of all incoming signals takes place. If the resulting depolarization passes a certain threshold, a new action potential is generated in an all-or-none fashion. Postsynaptic spines, dendrites, the soma, the axon and presynaptic boutons represent highly specialized compartments that are part of the complex morphology of neurons. In fact, without knowledge of ion channels or biophysical properties of the Rho family G proteins regulate cytoskeletal rearrangements through actin binding proteins such as Wasl (Wiskott-Aldrich syndrome-like, also known as N-WASP) and Diap1 (diaphanous homolog 1, also known as Dia1). In this way, they function in the formation of stress fibers, lamellipodia and other morphological processes. In addition, they also regulate gene expression and signal via Pi3k (Takai et al., 2001). Rab family G proteins function in protein sorting, intracellular vesicle trafficking, targeting, docking and fusion. Their mechanism is to activate effectors that directly influence vesicular membrane shape, vesicle tethering or vesicle motility. (Stenmark, 2009; Takai et al., 2001). By similar mechanisms, Arf G proteins function in intracellular trafficking, in particular in vesicle budding from endomembranes, in II.2.2. The Classical Ras Signaling Cascade The first findings indicating a neuronal involvement of the classical Ras G proteins came from experiments using the pheochromocytoma cell line (PC12). Overexpression of Hras, Nras or infection with the Kirsten murine sarcoma virus led to neuronal differentiation of these cells, which was recognized by the outgrowth of II.3. Controversies in the Research of Neuronal Ras Signaling Since publication of the findings described above, research on neuronal Ras signaling has led to many controversies. In this regard, one experimental system in particular appears to have given rise to most of the controversies in the field. Extensive research on Ras signaling is conducted using activated mutants of Ras proteins. The activated mutated protein is able to bind GTP, but unable to hydrolyze it to GDP and therefore remains in a constitutively active state (Karnoub and Weinberg, 2008). The corresponding frequently used Glycine to Valine mutation at amino acid (aa) position 12 (G12V) is normally found in oncogenic Hras. II.5.1. Specificity of Ras GEFs GEFs that activate classical Ras G proteins in the brain belong to three families, the Sos, Rasgrf and Rasgrp family. In case of the Rasgrf and Rasgrp proteins, an activity towards the Rras/Mras subfamily besides the classical Ras G proteins seems to be a general pattern of specificity. The activity of Sos GEFs seems to be restricted Rasgrp1, Rasgrp2a, Rasgrp2b and Rasgrp3. Rasgrp1 mRNA and protein are highly expressed in the brain. It is found in the olfactory bulb, cortex, caudo-putamen (including striatum), hippocampus and thalamus, but only at very low levels in midbrain, cerebellum, pons and medulla
Proceedings of the National Academy of Sciences of the United States of America, 2010
We describe a powerful system for revealing the direct monosynaptic inputs to specific cell types in Cre-expressing transgenic mice through the use of Cre-dependent helper virus and a modified rabies virus. We generated helper viruses that target gene expression to Cre-expressing cells, allowing us to control initial rabies virus infection and subsequent monosynaptic retrograde spread. Investigators can use this system to elucidate the connections onto a desired cell type in a high-throughput manner, limited only by the availability of Cre mouse lines. This method allows for identification of circuits that would be extremely tedious or impossible to study with other methods and can be used to build subcircuit maps of inputs onto many different types of cells within the same brain region. Furthermore, by expressing various transgenes from the rabies genome, this system also has the potential to allow manipulation of targeted neuronal circuits without perturbing neighboring cells. transsynaptic | pseudotyped virus | adeno-associated virus | EnvA | TVA O ne of the most intractable problems in systems neuroscience has been the systematic description of neural connectivity in the intact mammalian brain. Many different types of neurons, each with distinct connectivity and function, can inhabit the same brain region. Even within a single neocortical column, dozens of types of projection neurons and local interneurons perform the computations that ultimately lead to the spiking output of that column. Through painstaking studies using molecular and cell biology techniques, electron microscopy, and electrophysiology, we are beginning to understand how a neuron's connectivity contributes to its function in the circuit in which it is embedded, but we lack efficient means for performing circuit-level analyses in vivo. Especially in brain regions with considerable neuronal heterogeneity, we are still greatly limited in our ability to study how groups of cells form their fine-scale connections, how these connections change over time, and how this plasticity affects a cell type's computational role in a dynamic circuit.
Dynamic regulation of RGS2 suggests a novel mechanism in G-protein signaling and neuronal plasticity
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1998
Long-term neuronal plasticity is known to be dependent on rapid de novo synthesis of mRNA and protein, and recent studies provide insight into the molecules involved in this response. Here, we demonstrate that mRNA encoding a member of the regulator of G-protein signaling (RGS) family, RGS2, is rapidly induced in neurons of the hippocampus, cortex, and striatum in response to stimuli that evoke plasticity. Although several members of the RGS family are expressed in brain with discrete neuronal localizations, RGS2 appears unique in that its expression is dynamically responsive to neuronal activity. In biochemical assays, RGS2 stimulates the GTPase activity of the alpha subunit of Gq and Gi1. The effect on Gi1 was observed only after reconstitution of the protein in phospholipid vesicles containing M2 muscarinic acetylcholine receptors. RGS2 also inhibits both Gq- and Gi-dependent responses in transfected cells. These studies suggest a novel mechanism linking neuronal activity and sig...
Regulation of cpg15 by signaling pathways that mediate synaptic plasticity
Molecular and Cellular Neuroscience, 2003
Transcriptional activation is a key link between neuronal activity and long-term synaptic plasticity. Little is known about genes responding to this activation whose products directly effect functional and structural changes at the synapse. cpg15 is an activity-regulated gene encoding a membrane-bound ligand that regulates dendritic and axonal arbor growth and synaptic maturation. We report that cpg15 is an immediate-early gene induced by Ca 2ϩ influx through NMDA receptors and L-type voltage-sensitive calcium channels. Activitydependent cpg15 expression requires convergent activation of the CaM kinase and MAP kinase pathways. Although activation of PKA is not required for activity-dependent expression, cpg15 is induced by cAMP in active neurons. CREB binds the cpg15 promoter in vivo and partially regulates its activity-dependent expression. cpg15 is an effector gene that is a target for signal transduction pathways that mediate synaptic plasticity and thus may take part in an activity-regulated transcriptional program that directs long-term changes in synaptic connections.
Frontiers in Cellular Neuroscience
Editorial on the Research Topic Biology of brain disorders-Cellular substrates for disrupted synaptic function and experience-dependent plasticity This Research Topic on the "Biology of Brain Disorders: Cellular Substrates for Disrupted Synaptic Function and Experience-Dependent Plasticity" is a continuation of a series of topics and conferences on Brain Disorders that started in 2016. The topic aims to highlight the convergences and divergences between different types of brain disorders, including neuropsychiatric, neurological, and neurodegenerative. These pathologies remain one of the major problems in healthcare, and their incidence has continued to grow over the years. Consequently, one of the challenges that have captivated neuroscientists for decades is developing and exploiting sophisticated experimental approaches to understand how brain disorders arise and affect different features of brain function, including changes in synaptic transmission and plasticity. Indeed the field of neuroscience, among other areas of health sciences, has witnessed great technological advancements in the last several years, and has emerged as a positive circle of discovery and understanding: as new technologies are being developed, new mechanisms are discovered, and the need to understand the operating principle of such mechanisms in specific neuronal connections stimulates more research.