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Samadi M, Hales CA, Lustberg DJ, Farris S, Ross MR, Zhao M, Hepler JR, Harbin NH, Robinson ESJ, Banks PJ, Bashir ZI, Dudek SM. Mechanisms of mGluR-dependent plasticity in hippocampal area CA2. Hippocampus 2023; 33:730-744. [PMID: 36971428 PMCID: PMC10213158 DOI: 10.1002/hipo.23529] [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] [Received: 02/18/2023] [Revised: 03/04/2023] [Accepted: 03/08/2023] [Indexed: 03/29/2023]
Abstract
Pyramidal cells in hippocampal area CA2 have synaptic properties that are distinct from the other CA subregions. Notably, this includes a lack of typical long-term potentiation of stratum radiatum synapses. CA2 neurons express high levels of several known and potential regulators of metabotropic glutamate receptor (mGluR)-dependent signaling including Striatal-Enriched Tyrosine Phosphatase (STEP) and several Regulator of G-protein Signaling (RGS) proteins, yet the functions of these proteins in regulating mGluR-dependent synaptic plasticity in CA2 are completely unknown. Thus, the aim of this study was to examine mGluR-dependent synaptic depression and to determine whether STEP and the RGS proteins RGS4 and RGS14 are involved. Using whole cell voltage-clamp recordings from mouse pyramidal cells, we found that mGluR agonist-induced long-term depression (mGluR-LTD) is more pronounced in CA2 compared with that observed in CA1. This mGluR-LTD in CA2 was found to be protein synthesis and STEP dependent, suggesting that CA2 mGluR-LTD shares mechanistic processes with those seen in CA1, but in addition, RGS14, but not RGS4, was essential for mGluR-LTD in CA2. In addition, we found that exogenous application of STEP could rescue mGluR-LTD in RGS14 KO slices. Supporting a role for CA2 synaptic plasticity in social cognition, we found that RGS14 KO mice had impaired social recognition memory as assessed in a social discrimination task. These results highlight possible roles for mGluRs, RGS14, and STEP in CA2-dependent behaviors, perhaps by biasing the dominant form of synaptic plasticity away from LTP and toward LTD in CA2.
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Affiliation(s)
- Mahsa Samadi
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences BuildingUniversity Walk, University of BristolBristolUKBS8 1TD
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
- Present address:
Faculty Education Office, Faculty of Medicine, Imperial College London, Hammersmith Campus, Wolfson Education CentreLondonUKW12 0NN
| | - Claire A. Hales
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences BuildingUniversity Walk, University of BristolBristolUKBS8 1TD
- Present address:
Department of Psychology, Djavad Mowafaghian Centre for Brain HealthUniversity of British Columbia2215, Wesbrook MallVancouverBritish ColumbiaV6T 1Z3Canada
| | - Daniel J. Lustberg
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
- Present address:
Mouse Pharmacology GroupPsychogenics Inc215 College RoadParamusNew Jersey07652USA
| | - Shannon Farris
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
- Present address:
Fralin Biomedical Research Institute at Virginia TechRoanokeVirginia24014USA
| | - Madeleine R. Ross
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
| | - Meilan Zhao
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
| | - John R. Hepler
- Department of Pharmacology and Chemical BiologyEmory University School of Medicine100 Woodruff CircleAtlantaGeorgia30322USA
| | - Nicholas H. Harbin
- Department of Pharmacology and Chemical BiologyEmory University School of Medicine100 Woodruff CircleAtlantaGeorgia30322USA
| | - Emma S. J. Robinson
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences BuildingUniversity Walk, University of BristolBristolUKBS8 1TD
| | - Paul J. Banks
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences BuildingUniversity Walk, University of BristolBristolUKBS8 1TD
| | - Zafar I. Bashir
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences BuildingUniversity Walk, University of BristolBristolUKBS8 1TD
| | - Serena M. Dudek
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIH)111 T.W. Alexander Drive, Research Triangle ParkDurhamNorth Carolina27709USA
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2
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Harbin NH, Lustberg DJ, Hurst C, Pare J, Crotty KM, Waters AL, Yeligar SM, Smith Y, Seyfried NT, Weinshenker D, Hepler JR. RGS14 limits seizure-induced mitochondrial oxidative stress and pathology in hippocampus. Neurobiol Dis 2023; 181:106128. [PMID: 37075948 PMCID: PMC10259180 DOI: 10.1016/j.nbd.2023.106128] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/02/2023] [Accepted: 04/14/2023] [Indexed: 04/21/2023] Open
Abstract
RGS14 is a complex multifunctional scaffolding protein that is highly enriched within pyramidal cells (PCs) of hippocampal area CA2. In these neurons, RGS14 suppresses glutamate-induced calcium influx and related G protein and ERK signaling in dendritic spines to restrain postsynaptic signaling and plasticity. Previous findings show that, unlike PCs of hippocampal areas CA1 and CA3, CA2 PCs are resistant to a number of neurological insults, including degeneration caused by temporal lobe epilepsy (TLE). While RGS14 is protective against peripheral injury, similar roles for RGS14 during pathological injury in hippocampus remain unexplored. Recent studies showed that area CA2 modulates hippocampal excitability, generates epileptiform activity and promotes hippocampal pathology in animal models and patients with TLE. Because RGS14 suppresses CA2 excitability and signaling, we hypothesized that RGS14 would moderate seizure behavior and early hippocampal pathology following seizure activity, possibly affording protection to CA2 PCs. Using kainic acid (KA) to induce status epilepticus (KA-SE) in mice, we show that the loss of RGS14 (RGS14 KO) accelerated onset of limbic motor seizures and mortality compared to wild type (WT) mice, and that KA-SE upregulated RGS14 protein expression in CA2 and CA1 PCs of WT. Our proteomics data show that the loss of RGS14 impacted the expression of a number of proteins at baseline and after KA-SE, many of which associated unexpectedly with mitochondrial function and oxidative stress. RGS14 was shown to localize to the mitochondria in CA2 PCs of mice and reduce mitochondrial respiration in vitro. As a readout of oxidative stress, we found that RGS14 KO dramatically increased 3- nitrotyrosine levels in CA2 PCs, which was greatly exacerbated following KA-SE and correlated with a lack of superoxide dismutase 2 (SOD2) induction. Assessing for hallmarks of seizure pathology in RGS14 KO, we unexpectedly found no differences in neuronal injury in CA2 PCs. However, we observed a striking and surprising lack of microgliosis in CA1 and CA2 of RGS14 KO compared to WT. Together, our data demonstrate a newly appreciated role for RGS14 in limiting intense seizure activity and pathology in hippocampus. Our findings are consistent with a model where RGS14 limits seizure onset and mortality and, after seizure, is upregulated to support mitochondrial function, prevent oxidative stress in CA2 PCs, and promote microglial activation in hippocampus.
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Affiliation(s)
- N H Harbin
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
| | - D J Lustberg
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta, GA 30322, United States
| | - C Hurst
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd, 4001 Rollins Research Center, Atlanta, GA 30322, United States.
| | - J Pare
- Emory National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30329, United States.
| | - K M Crotty
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University, 1364 Clifton Road NE, Suite H-153, Atlanta, GA 30322, United States; Atlanta Veterans Affairs Health Care System, 1670 Clairmont Road, Decatur, GA 30033, United States.
| | - A L Waters
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
| | - S M Yeligar
- Department of Medicine, Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Emory University, 1364 Clifton Road NE, Suite H-153, Atlanta, GA 30322, United States; Atlanta Veterans Affairs Health Care System, 1670 Clairmont Road, Decatur, GA 30033, United States.
| | - Y Smith
- Emory National Primate Research Center, Emory University, 954, Gatewood Rd NE, Atlanta, GA 30329, United States; Department of Neurology, Emory University School of Medicine, 12 Executive Park Dr NE, Atlanta, GA, 30322, United States.
| | - N T Seyfried
- Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Rd, 4001 Rollins Research Center, Atlanta, GA 30322, United States.
| | - D Weinshenker
- Department of Human Genetics, Emory University School of Medicine, 615 Michael Street, Suite 301, Atlanta, GA 30322, United States.
| | - J R Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, 1510 Clifton Rd, 5001 Rollins Research Ctr, Atlanta, GA 30322, United States.
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3
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Guo Y, Fu Y, Sun W. 50 Hz Magnetic Field Exposure Inhibited Spontaneous Movement of Zebrafish Larvae through ROS-Mediated syn2a Expression. Int J Mol Sci 2023; 24:ijms24087576. [PMID: 37108734 PMCID: PMC10144198 DOI: 10.3390/ijms24087576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/21/2023] [Accepted: 04/15/2023] [Indexed: 04/29/2023] Open
Abstract
Extremely low frequency electromagnetic field (ELF-EMF) exists widely in public and occupational environments. However, its potential adverse effects and the underlying mechanism on nervous system, especially behavior are still poorly understood. In this study, zebrafish embryos (including a transfected synapsin IIa (syn2a) overexpression plasmid) at 3 h post-fertilization (hpf) were exposed to a 50-Hz magnetic field (MF) with a series of intensities (100, 200, 400 and 800 μT, respectively) for 1 h or 24 h every day for 5 days. Results showed that, although MF exposure did not affect the basic development parameters including hatching rate, mortality and malformation rate, yet MF at 200 μT could significantly induce spontaneous movement (SM) hypoactivity in zebrafish larvae. Histological examination presented morphological abnormalities of the brain such as condensed cell nucleus and cytoplasm, increased intercellular space. Moreover, exposure to MF at 200 μT inhibited syn2a transcription and expression, and increased reactive oxygen species (ROS) level as well. Overexpression of syn2a could effectively rescue MF-induced SM hypoactivity in zebrafish. Pretreatment with N-acetyl-L-cysteine (NAC) could not only recover syn2a protein expression which was weakened by MF exposure, but also abolish MF-induced SM hypoactivity. However, syn2a overexpression did not affect MF-increased ROS. Taken together, the findings suggested that exposure to a 50-Hz MF inhibited spontaneous movement of zebrafish larvae via ROS-mediated syn2a expression in a nonlinear manner.
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Affiliation(s)
- Yixin Guo
- Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine, Hangzhou 310058, China
- Institute of Environmental Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Yiti Fu
- Institute of Environmental Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
| | - Wenjun Sun
- Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine, Hangzhou 310058, China
- Institute of Environmental Medicine, Zhejiang University School of Medicine, Hangzhou 310058, China
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4
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Montanez-Miranda C, Bramlett SN, Hepler JR. RGS14 expression in CA2 hippocampus, amygdala, and basal ganglia: Implications for human brain physiology and disease. Hippocampus 2023; 33:166-181. [PMID: 36541898 PMCID: PMC9974931 DOI: 10.1002/hipo.23492] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022]
Abstract
RGS14 is a multifunctional scaffolding protein that is highly expressed within postsynaptic spines of pyramidal neurons in hippocampal area CA2. Known roles of RGS14 in CA2 include regulating G protein, H-Ras/ERK, and calcium signaling pathways to serve as a natural suppressor of synaptic plasticity and postsynaptic signaling. RGS14 also shows marked postsynaptic expression in major structures of the limbic system and basal ganglia, including the amygdala and both the ventral and dorsal subdivisions of the striatum. In this review, we discuss the signaling functions of RGS14 and its role in postsynaptic strength (long-term potentiation) and spine structural plasticity in CA2 hippocampal neurons, and how RGS14 suppression of plasticity impacts linked behaviors such as spatial learning, object memory, and fear conditioning. We also review RGS14 expression in the limbic system and basal ganglia and speculate on its possible roles in regulating plasticity in these regions, with a focus on behaviors related to emotion and motivation. Finally, we explore the functional implications of RGS14 in various brain circuits and speculate on its possible roles in certain disease states such as hippocampal seizures, addiction, and anxiety disorders.
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Affiliation(s)
| | | | - John R. Hepler
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, 30322-3090
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5
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Harbin NH, Lustberg DJ, Hurst C, Pare JF, Crotty KM, Waters AL, Yeligar SM, Smith Y, Seyfried NT, Weinshenker D, Hepler JR. RGS14 is neuroprotective against seizure-induced mitochondrial oxidative stress and pathology in hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.01.526349. [PMID: 36778349 PMCID: PMC9915580 DOI: 10.1101/2023.02.01.526349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
RGS14 is a complex multifunctional scaffolding protein that is highly enriched within pyramidal cells (PCs) of hippocampal area CA2. There, RGS14 suppresses glutamate-induced calcium influx and related G protein and ERK signaling in dendritic spines to restrain postsynaptic signaling and plasticity. Previous findings show that, unlike PCs of hippocampal areas CA1 and CA3, CA2 PCs are resistant to a number of neurological insults, including degeneration caused by temporal lobe epilepsy (TLE). While RGS14 is protective against peripheral injury, similar roles for RGS14 during pathological injury in hippocampus remain unexplored. Recent studies show that area CA2 modulates hippocampal excitability, generates epileptiform activity and promotes hippocampal pathology in animal models and patients with TLE. Because RGS14 suppresses CA2 excitability and signaling, we hypothesized that RGS14 would moderate seizure behavior and early hippocampal pathology following seizure activity. Using kainic acid (KA) to induce status epilepticus (KA-SE) in mice, we show loss of RGS14 (RGS14 KO) accelerated onset of limbic motor seizures and mortality compared to wild type (WT) mice, and that KA-SE upregulated RGS14 protein expression in CA2 and CA1 PCs of WT. Utilizing proteomics, we saw loss of RGS14 impacted the expression of a number of proteins at baseline and after KA-SE, many of which associated unexpectedly with mitochondrial function and oxidative stress. RGS14 was shown to localize to the mitochondria in CA2 PCs of mice and reduce mitochondrial respiration in vitro . As a readout of oxidative stress, we found RGS14 KO dramatically increased 3-nitrotyrosine levels in CA2 PCs, which was greatly exacerbated following KA-SE and correlated with a lack of superoxide dismutase 2 (SOD2) induction. Assessing for hallmarks of seizure pathology in RGS14 KO, we observed worse neuronal injury in area CA3 (but none in CA2 or CA1), and a lack of microgliosis in CA1 and CA2 compared to WT. Together, our data demonstrates a newly appreciated neuroprotective role for RGS14 against intense seizure activity in hippocampus. Our findings are consistent with a model where, after seizure, RGS14 is upregulated to support mitochondrial function and prevent oxidative stress in CA2 PCs, limit seizure onset and hippocampal neuronal injury, and promote microglial activation in hippocampus.
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6
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Lustberg DJ, Liu JQ, Iannitelli AF, Vanderhoof SO, Liles LC, McCann KE, Weinshenker D. Norepinephrine and dopamine contribute to distinct repetitive behaviors induced by novel odorant stress in male and female mice. Horm Behav 2022; 144:105205. [PMID: 35660247 PMCID: PMC10216880 DOI: 10.1016/j.yhbeh.2022.105205] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/18/2022] [Accepted: 05/19/2022] [Indexed: 12/30/2022]
Abstract
Exposure to unfamiliar odorants induces an array of repetitive defensive and non-defensive behaviors in rodents which likely reflect adaptive stress responses to the uncertain valence of novel stimuli. Mice genetically deficient for dopamine β-hydroxylase (Dbh-/-) lack the enzyme required to convert dopamine (DA) into norepinephrine (NE), resulting in globally undetectable NE and supranormal DA levels. Because catecholamines modulate novelty detection and reactivity, we investigated the effects of novel plant-derived odorants on repetitive behaviors in Dbh-/- mice and Dbh+/- littermate controls, which have catecholamine levels comparable to wild-type mice. Unlike Dbh+/- controls, which exhibited vigorous digging in response to novel odorants, Dbh-/- mice displayed excessive grooming. Drugs that block NE synthesis or neurotransmission suppressed odorant-induced digging in Dbh+/- mice, while a DA receptor antagonist attenuated grooming in Dbh-/- mice. The testing paradigm elicited high circulating levels of corticosterone regardless of Dbh genotype, indicating that NE is dispensable for this systemic stress response. Odorant exposure increased NE and DA abundance in the prefrontal cortex (PFC) of Dbh+/- mice, while Dbh-/- animals lacked NE and had elevated PFC DA levels that were unaffected by novel smells. Together, these findings suggest that novel odorant-induced increases in central NE tone contribute to repetitive digging and reflect psychological stress, while central DA signaling contributes to repetitive grooming. Further, we have established a simple method for repeated assessment of stress-induced repetitive behaviors in mice, which may be relevant for modeling neuropsychiatric disorders like Tourette syndrome or obsessive-compulsive disorder that are characterized by stress-induced exacerbation of compulsive symptoms.
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Affiliation(s)
- Daniel J Lustberg
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Joyce Q Liu
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Alexa F Iannitelli
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Samantha O Vanderhoof
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - L Cameron Liles
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Katharine E McCann
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David Weinshenker
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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7
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RGS14 Regulation of Post-Synaptic Signaling and Spine Plasticity in Brain. Int J Mol Sci 2021; 22:ijms22136823. [PMID: 34201943 PMCID: PMC8268017 DOI: 10.3390/ijms22136823] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/12/2021] [Accepted: 06/14/2021] [Indexed: 02/06/2023] Open
Abstract
The regulator of G-protein signaling 14 (RGS14) is a multifunctional signaling protein that regulates post synaptic plasticity in neurons. RGS14 is expressed in the brain regions essential for learning, memory, emotion, and stimulus-induced behaviors, including the basal ganglia, limbic system, and cortex. Behaviorally, RGS14 regulates spatial and object memory, female-specific responses to cued fear conditioning, and environmental- and psychostimulant-induced locomotion. At the cellular level, RGS14 acts as a scaffolding protein that integrates G protein, Ras/ERK, and calcium/calmodulin signaling pathways essential for spine plasticity and cell signaling, allowing RGS14 to naturally suppress long-term potentiation (LTP) and structural plasticity in hippocampal area CA2 pyramidal cells. Recent proteomics findings indicate that RGS14 also engages the actomyosin system in the brain, perhaps to impact spine morphogenesis. Of note, RGS14 is also a nucleocytoplasmic shuttling protein, where its role in the nucleus remains uncertain. Balanced nuclear import/export and dendritic spine localization are likely essential for RGS14 neuronal functions as a regulator of synaptic plasticity. Supporting this idea, human genetic variants disrupting RGS14 localization also disrupt RGS14’s effects on plasticity. This review will focus on the known and unexplored roles of RGS14 in cell signaling, physiology, disease and behavior.
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