title: Dexras1 a unique ras-GTPase interacts with NMDA receptor activity and provides a novel dissociation between anxiety, working memory and sensory gating.
abstract: Dexras1 is a novel GTPase that acts at a confluence of signaling mechanisms associated with psychiatric and neurological disease including NMDA receptors, NOS1AP and nNOS. Recent work has shown that Dexras1 mediates iron trafficking and NMDA-dependent neurodegeneration but a role for Dexras1 in normal brain function or psychiatric disease has not been studied. To test for such a role, mice with germline knockout (KO) of Dexras1 were assayed for behavioral abnormalities as well as changes in NMDA receptor subunit protein expression. Because Dexras1 is up-regulated during stress or by dexamethasone treatment, we included measures associated with emotion including anxiety and depression. Baseline anxiety-like measures (open field and zero maze) were not altered, nor were depression-like behavior (tail suspension). Measures of memory function yielded mixed results, with no changes in episodic memory (novel object recognition) but a significant decrement on working memory (T-maze). Alternatively, there was an increase in pre-pulse inhibition (PPI), without concomitant changes in either startle amplitude or locomotor activity. PPI data are consistent with the direction of change seen following exposure to dopamine D2 antagonists. An examination of NMDA subunit expression levels revealed an increased expression of the NR2A subunit, contrary to previous studies demonstrating down-regulation of the receptor following antipsychotic exposure (Schmitt et al., 2003) and up-regulation after exposure to isolation rearing (Turnock-Jones et al., 2009). These findings suggest a potential role for Dexras1 in modulating a selective subset of psychiatric symptoms, possibly via its interaction with NMDARs and/or other disease-related binding-partners. Furthermore, data suggest that modulating Dexras1 activity has contrasting effects on emotional, sensory and cognitive domains.
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States. Electronic address: gregc@mail.med.upenn.edu.
authors.forename: G C
authors.initials: GC
authors.lastname: Carlson
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: R E
authors.initials: RE
authors.lastname: Lin
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Department of Pharmacology, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: B R
authors.initials: BR
authors.lastname: Brookshire
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: R S
authors.initials: RS
authors.lastname: White
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Department of Pharmacology, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: I
authors.initials: I
authors.lastname: Lucki
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States.
authors.forename: S J
authors.initials: SJ
authors.lastname: Siegel
authors.affiliation: Department of Psychiatry, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Center for Neurobiology and Behavior, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States; Department of Pharmacology, The Perlman School of Medicine at the University of Pennsylvania, 125 S 31st Street, Translational Research Building, Philadelphia, PA 19104, United States. Electronic address: sangwonk@mail.med.upenn.edu.
authors.forename: S F
authors.initials: SF
authors.lastname: Kim
mesh_terms: D000818:Animals; D001008:Anxiety Disorders / Q000378:metabolism*; D018782:Maze Learning / Q000502:physiology; D061212:Memory, Episodic; D008570:Memory, Short-Term / Q000502:physiology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology; D065808:Prepulse Inhibition / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D021641:Recognition, Psychology / Q000502:physiology; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D016194:Receptors, N-Methyl-D-Aspartate; C498511:Rasd1 protein, mouse; D018631:ras Proteins
keywords: GTPases; NMDA; learning and memory; prepulse inhibition; sensory