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Suardi GAM, Haddad LA. FMRP ribonucleoprotein complexes and RNA homeostasis. ADVANCES IN GENETICS 2020; 105:95-136. [PMID: 32560791 DOI: 10.1016/bs.adgen.2020.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Fragile Mental Retardation 1 gene (FMR1), at Xq27.3, encodes the fragile mental retardation protein (FMRP), and displays in its 5'-untranslated region a series of polymorphic CGG triplet repeats that may undergo dynamic mutation. Fragile X syndrome (FXS) is the leading cause of inherited intellectual disability among men, and is most frequently due to FMR1 full mutation and consequent transcription repression. FMR1 premutations may associate with at least two other clinical conditions, named fragile X-associated primary ovarian insufficiency (FXPOI) and tremor and ataxia syndrome (FXTAS). While FXPOI and FXTAS appear to be mediated by FMR1 mRNA accumulation, relative reduction of FMRP, and triplet repeat translation, FXS is due to the lack of the RNA-binding protein FMRP. Besides its function as mRNA translation repressor in neuronal and stem/progenitor cells, RNA editing roles have been assigned to FMRP. In this review, we provide a brief description of FMR1 transcribed microsatellite and associated clinical disorders, and discuss FMRP molecular roles in ribonucleoprotein complex assembly and trafficking, as well as aspects of RNA homeostasis affected in FXS cells.
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Affiliation(s)
- Gabriela Aparecida Marcondes Suardi
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
| | - Luciana Amaral Haddad
- Human Genome and Stem Cell Research Center, Department of Genetics and Evolutionary Biology, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
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2
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Oliva CA, Montecinos-Oliva C, Inestrosa NC. Wnt Signaling in the Central Nervous System: New Insights in Health and Disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 153:81-130. [PMID: 29389523 DOI: 10.1016/bs.pmbts.2017.11.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Since its discovery, Wnt signaling has been shown to be one of the most crucial morphogens in development and during the maturation of central nervous system. Its action is relevant during the establishment and maintenance of synaptic structure and neuronal function. In this chapter, we will discuss the most recent evidence on these aspects, and we will explore the evidence that involves Wnt signaling on other less known functions, such as in adult neurogenesis, in the generation of oscillatory neural rhythms, and in adult behavior. The dysfunction of Wnt signaling at different levels will be also discussed, in particular in those aspects that have been found to be linked with several neurodegenerative diseases and neurological disorders. Finally, we will address the possibility of Wnt signaling manipulation to treat those pathophysiological aspects.
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Affiliation(s)
- Carolina A Oliva
- Center for Aging and Regeneration (CARE-UC), Pontifical Catholic University of Chile, Santiago, Chile
| | - Carla Montecinos-Oliva
- Center for Aging and Regeneration (CARE-UC), Pontifical Catholic University of Chile, Santiago, Chile; Interdisciplinary Institute for Neuroscience (IINS), University of Bordeaux, Bordeaux, France
| | - Nibaldo C Inestrosa
- Center for Aging and Regeneration (CARE-UC), Pontifical Catholic University of Chile, Santiago, Chile; Center for Healthy Brain Ageing, University of New South Wales, Sydney, NSW, Australia; Center of Excellence in Biomedicine of Magallanes (CEBIMA), University of Magallanes, Punta Arenas, Chile.
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3
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Schaefer TL, Davenport MH, Grainger LM, Robinson CK, Earnheart AT, Stegman MS, Lang AL, Ashworth AA, Molinaro G, Huber KM, Erickson CA. Acamprosate in a mouse model of fragile X syndrome: modulation of spontaneous cortical activity, ERK1/2 activation, locomotor behavior, and anxiety. J Neurodev Disord 2017; 9:6. [PMID: 28616095 PMCID: PMC5467053 DOI: 10.1186/s11689-017-9184-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 01/13/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Fragile X Syndrome (FXS) occurs as a result of a silenced fragile X mental retardation 1 gene (FMR1) and subsequent loss of fragile X mental retardation protein (FMRP) expression. Loss of FMRP alters excitatory/inhibitory signaling balance, leading to increased neuronal hyperexcitability and altered behavior. Acamprosate (the calcium salt of N-acetylhomotaurinate), a drug FDA-approved for relapse prevention in the treatment of alcohol dependence in adults, is a novel agent with multiple mechanisms that may be beneficial for people with FXS. There are questions regarding the neuroactive effects of acamprosate and the significance of the molecule's calcium moiety. Therefore, the electrophysiological, cellular, molecular, and behavioral effects of acamprosate were assessed in the Fmr1-/y (knock out; KO) mouse model of FXS controlling for the calcium salt in several experiments. METHODS Fmr1 KO mice and their wild-type (WT) littermates were utilized to assess acamprosate treatment on cortical UP state parameters, dendritic spine density, and seizure susceptibility. Brain extracellular-signal regulated kinase 1/2 (ERK1/2) activation was used to investigate this signaling molecule as a potential biomarker for treatment response. Additional adult mice were used to assess chronic acamprosate treatment and any potential effects of the calcium moiety using CaCl2 treatment on behavior and nuclear ERK1/2 activation. RESULTS Acamprosate attenuated prolonged cortical UP state duration, decreased elevated ERK1/2 activation in brain tissue, and reduced nuclear ERK1/2 activation in the dentate gyrus in KO mice. Acamprosate treatment modified behavior in anxiety and locomotor tests in Fmr1 KO mice in which control-treated KO mice were shown to deviate from control-treated WT mice. Mice treated with CaCl2 were not different from saline-treated mice in the adult behavior battery or nuclear ERK1/2 activation. CONCLUSIONS These data indicate that acamprosate, and not calcium, improves function reminiscent of reduced anxiety-like behavior and hyperactivity in Fmr1 KO mice and that acamprosate attenuates select electrophysiological and molecular dysregulation that may play a role in the pathophysiology of FXS. Differences between control-treated KO and WT mice were not evident in a recognition memory test or in examination of acoustic startle response/prepulse inhibition which impeded conclusions from being made about the treatment effects of acamprosate in these instances.
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Affiliation(s)
- Tori L Schaefer
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Matthew H Davenport
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Lindsay M Grainger
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Chandler K Robinson
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Anthony T Earnheart
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
| | - Melinda S Stegman
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: Division of Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229 USA
| | - Anna L Lang
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202 USA
| | - Amy A Ashworth
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA.,Present address: BlackbookHR, Cincinnati, OH 45202 USA
| | - Gemma Molinaro
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kimberly M Huber
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Craig A Erickson
- Division of Psychiatry, MLC 7004, Cincinnati Children's Research Foundation, 3333 Burnet Ave., Cincinnati, OH 45229-3039 USA
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Shi Z, Zhang W, Lu Y, Lu Y, Xu L, Fang Q, Wu M, Jia M, Wang Y, Dong L, Yan X, Yang S, Yuan F. Aquaporin 4-Mediated Glutamate-Induced Astrocyte Swelling Is Partially Mediated through Metabotropic Glutamate Receptor 5 Activation. Front Cell Neurosci 2017; 11:116. [PMID: 28503134 PMCID: PMC5408017 DOI: 10.3389/fncel.2017.00116] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 04/07/2017] [Indexed: 12/17/2022] Open
Abstract
Astrocytes are one of the most abundant cell types in the mammalian central nervous system (CNS), and astrocyte swelling is the primary event associated with brain edema. Glutamate, the principal excitatory amino acid neurotransmitter in the CNS, is released at high levels after brain injury including cerebral ischemia. This leads to astrocyte swelling, which we previously demonstrated is related to metabotropic glutamate receptor (mGluR) activation. Aquaporin 4 (AQP4), the predominant water channel in the brain, is expressed in astrocyte endfeet and plays an important role in brain edema following ischemia. Studies recently showed that mGluR5 is also expressed on astrocytes. Therefore, it is worth investigating whether AQP4 mediates the glutamate-induced swelling of astrocytes via mGluR5. In the present study, we found that 1 mM glutamate induced astrocyte swelling, quantified by the cell perimeter, but it had no effect on astrocyte viability measured by the cell counting kit-8 (CCK-8) and lactate dehydrogenase (LDH) assays. Quantitative reverse transcription polymerase chain reaction analyses revealed that AQP4, among AQP1, 4, 5, 9 and 11, was the main molecular expressed in cultured astrocytes. Glutamate-induced cell swelling was accompanied by a concentration-dependent change in AQP4 expression. Furthermore, RNAi technology revealed that AQP4 gene silencing inhibited glutamate-induced astrocyte swelling. Moreover, we found that mGluR5 expression was greatest among the mGluRs in cultured astrocytes and was co-expressed with AQP4. Activation of mGluR5 in cultured astrocytes using (S)-3,5-dihydroxyphenylglycine (DHPG), an mGluR5 agonist, mimicked the effect of glutamate. This effect was abolished by co-incubation with the mGluR5 antagonist fenobam but was not influenced by DL-threo-β-benzyloxyaspartic acid (DL-TBOA), a glutamate transporter inhibitor. Finally, experiments in a rat model of transient middle cerebral artery occlusion (tMCAO) revealed that co-expression of mGluR5 and AQP4 was increased in astrocyte endfeet around capillaries in the penumbra, and this was accompanied by brain edema. Collectively, these results suggest that glutamate induces cell swelling and alters AQP4 expression in astrocytes via mGluR5 activation, which may provide a novel approach for the treatment of edema following brain injury.
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Affiliation(s)
- Zhongfang Shi
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Wei Zhang
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Yang Lu
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Yi Lu
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Lixin Xu
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Qing Fang
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Min Wu
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Mei Jia
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Yujiao Wang
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Liping Dong
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Xu Yan
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
| | - Shaohua Yang
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China.,Department of Pharmacology and Neuroscience, University of North Texas Health Science CenterFort Worth, TX, USA
| | - Fang Yuan
- Department of Pathophysiology, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical UniversityBeijing, China.,China National Clinical Research Center for Neurological DiseasesBeijing, China.,Beijing Key Laboratory of Central Nervous System InjuryBeijing, China.,Center of Stroke, Beijing Institute for Brain DisordersBeijing, China.,Beijing Key Laboratory of Translational Medicine for Cerebrovascular DiseaseBeijing, China
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Synaptic Plasticity, a Prominent Contributor to the Anxiety in Fragile X Syndrome. Neural Plast 2016; 2016:9353929. [PMID: 27239350 PMCID: PMC4864533 DOI: 10.1155/2016/9353929] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 04/04/2016] [Indexed: 01/03/2023] Open
Abstract
Fragile X syndrome (FXS) is an inheritable neuropsychological disease caused by expansion of the CGG trinucleotide repeat affecting the fmr1 gene on X chromosome, resulting in silence of the fmr1 gene and failed expression of FMRP. Patients with FXS suffer from cognitive impairment, sensory integration deficits, learning disability, anxiety, autistic traits, and so forth. Specifically, the morbidity of anxiety in FXS individuals remains high from childhood to adulthood. By and large, it is common that the change of brain plasticity plays a key role in the progression of disease. But for now, most studies excessively emphasized the one-sided factor on the change of synaptic plasticity participating in the generation of anxiety during the development of FXS. Here we proposed an integrated concept to acquire better recognition about the details of this process.
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6
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Neuron class-specific requirements for Fragile X Mental Retardation Protein in critical period development of calcium signaling in learning and memory circuitry. Neurobiol Dis 2016; 89:76-87. [PMID: 26851502 DOI: 10.1016/j.nbd.2016.02.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/27/2016] [Accepted: 02/02/2016] [Indexed: 01/22/2023] Open
Abstract
Neural circuit optimization occurs through sensory activity-dependent mechanisms that refine synaptic connectivity and information processing during early-use developmental critical periods. Fragile X Mental Retardation Protein (FMRP), the gene product lost in Fragile X syndrome (FXS), acts as an activity sensor during critical period development, both as an RNA-binding translation regulator and channel-binding excitability regulator. Here, we employ a Drosophila FXS disease model to assay calcium signaling dynamics with a targeted transgenic GCaMP reporter during critical period development of the mushroom body (MB) learning/memory circuit. We find FMRP regulates depolarization-induced calcium signaling in a neuron-specific manner within this circuit, suppressing activity-dependent calcium transients in excitatory cholinergic MB input projection neurons and enhancing calcium signals in inhibitory GABAergic MB output neurons. Both changes are restricted to the developmental critical period and rectified at maturity. Importantly, conditional genetic (dfmr1) rescue of null mutants during the critical period corrects calcium signaling defects in both neuron classes, indicating a temporally restricted FMRP requirement. Likewise, conditional dfmr1 knockdown (RNAi) during the critical period replicates constitutive null mutant defects in both neuron classes, confirming cell-autonomous requirements for FMRP in developmental regulation of calcium signaling dynamics. Optogenetic stimulation during the critical period enhances depolarization-induced calcium signaling in both neuron classes, but this developmental change is eliminated in dfmr1 null mutants, indicating the activity-dependent regulation requires FMRP. These results show FMRP shapes neuron class-specific calcium signaling in excitatory vs. inhibitory neurons in developing learning/memory circuitry, and that FMRP mediates activity-dependent regulation of calcium signaling specifically during the early-use critical period.
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7
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Navarro D, Alvarado M, Navarrete F, Giner M, Obregon MJ, Manzanares J, Berbel P. Gestational and early postnatal hypothyroidism alters VGluT1 and VGAT bouton distribution in the neocortex and hippocampus, and behavior in rats. Front Neuroanat 2015; 9:9. [PMID: 25741243 PMCID: PMC4330898 DOI: 10.3389/fnana.2015.00009] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 01/17/2015] [Indexed: 12/20/2022] Open
Abstract
Thyroid hormones are fundamental for the expression of genes involved in the development of the CNS and their deficiency is associated with a wide spectrum of neurological diseases including mental retardation, attention deficit-hyperactivity disorder and autism spectrum disorders. We examined in rat whether developmental and early postnatal hypothyroidism affects the distribution of vesicular glutamate transporter-1 (VGluT1; glutamatergic) and vesicular inhibitory amino acid transporter (VGAT; GABAergic) immunoreactive (ir) boutons in the hippocampus and somatosensory cortex, and the behavior of the pups. Hypothyroidism was induced by adding 0.02% methimazole (MMI) and 1% KClO4 to the drinking water starting at embryonic day 10 (E10; developmental hypothyroidism) and E21 (early postnatal hypothyroidism) until day of sacrifice at postnatal day 50. Behavior was studied using the acoustic prepulse inhibition (somatosensory attention) and the elevated plus-maze (anxiety-like assessment) tests. The distribution, density and size of VGluT1-ir and VGAT-ir boutons in the hippocampus and somatosensory cortex was abnormal in MMI pups and these changes correlate with behavioral changes, as prepulse inhibition of the startle response amplitude was reduced, and the percentage of time spent in open arms increased. In conclusion, both developmental and early postnatal hypothyroidism significantly decreases the ratio of GABAergic to glutamatergic boutons in dentate gyrus leading to an abnormal flow of information to the hippocampus and infragranular layers of the somatosensory cortex, and alter behavior in rats. Our data show cytoarchitectonic alterations in the basic excitatory hippocampal loop, and in local inhibitory circuits of the somatosensory cortex and hippocampus that might contribute to the delayed neurocognitive outcome observed in thyroid hormone deficient children born in iodine deficient areas, or suffering from congenital hypothyroidism.
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Affiliation(s)
- Daniela Navarro
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel HernándezAlicante, Spain
| | - Mayvi Alvarado
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel HernándezAlicante, Spain
- Instituto de Neuroetología, Universidad VeracruzanaXalapa, Veracruz, México
| | - Francisco Navarrete
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández and Consejo Superior de Investigaciones CientíficasAlicante, Spain
| | - Manuel Giner
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel HernándezAlicante, Spain
| | - Maria Jesus Obregon
- Instituto de investigaciones Biomédicas, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de MadridMadrid, Spain
| | - Jorge Manzanares
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández and Consejo Superior de Investigaciones CientíficasAlicante, Spain
| | - Pere Berbel
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel HernándezAlicante, Spain
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8
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Independent role for presynaptic FMRP revealed by an FMR1 missense mutation associated with intellectual disability and seizures. Proc Natl Acad Sci U S A 2015; 112:949-56. [PMID: 25561520 DOI: 10.1073/pnas.1423094112] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fragile X syndrome (FXS) results in intellectual disability (ID) most often caused by silencing of the fragile X mental retardation 1 (FMR1) gene. The resulting absence of fragile X mental retardation protein 1 (FMRP) leads to both pre- and postsynaptic defects, yet whether the pre- and postsynaptic functions of FMRP are independent and have distinct roles in FXS neuropathology remain poorly understood. Here, we demonstrate an independent presynaptic function for FMRP through the study of an ID patient with an FMR1 missense mutation. This mutation, c.413G > A (R138Q), preserves FMRP's canonical functions in RNA binding and translational regulation, which are traditionally associated with postsynaptic compartments. However, neuronally driven expression of the mutant FMRP is unable to rescue structural defects at the neuromuscular junction in fragile x mental retardation 1 (dfmr1)-deficient Drosophila, suggesting a presynaptic-specific impairment. Furthermore, mutant FMRP loses the ability to rescue presynaptic action potential (AP) broadening in Fmr1 KO mice. The R138Q mutation also disrupts FMRP's interaction with the large-conductance calcium-activated potassium (BK) channels that modulate AP width. These results reveal a presynaptic- and translation-independent function of FMRP that is linked to a specific subset of FXS phenotypes.
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9
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Berbel P, Navarro D, Román GC. An evo-devo approach to thyroid hormones in cerebral and cerebellar cortical development: etiological implications for autism. Front Endocrinol (Lausanne) 2014; 5:146. [PMID: 25250016 PMCID: PMC4158880 DOI: 10.3389/fendo.2014.00146] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 08/25/2014] [Indexed: 12/11/2022] Open
Abstract
The morphological alterations of cortical lamination observed in mouse models of developmental hypothyroidism prompted the recognition that these experimental changes resembled the brain lesions of children with autism; this led to recent studies showing that maternal thyroid hormone deficiency increases fourfold the risk of autism spectrum disorders (ASD), offering for the first time the possibility of prevention of some forms of ASD. For ethical reasons, the role of thyroid hormones on brain development is currently studied using animal models, usually mice and rats. Although mammals have in common many basic developmental principles regulating brain development, as well as fundamental basic mechanisms that are controlled by similar metabolic pathway activated genes, there are also important differences. For instance, the rodent cerebral cortex is basically a primary cortex, whereas the primary sensory areas in humans account for a very small surface in the cerebral cortex when compared to the associative and frontal areas that are more extensive. Associative and frontal areas in humans are involved in many neurological disorders, including ASD, attention deficit-hyperactive disorder, and dyslexia, among others. Therefore, an evo-devo approach to neocortical evolution among species is fundamental to understand not only the role of thyroid hormones and environmental thyroid disruptors on evolution, development, and organization of the cerebral cortex in mammals but also their role in neurological diseases associated to thyroid dysfunction.
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Affiliation(s)
- Pere Berbel
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández, Alicante, Spain
| | - Daniela Navarro
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández, Alicante, Spain
| | - Gustavo C. Román
- Department of Neurology, Weill Cornell Medical College, Cornell University, New York, NY, USA
- Methodist Neurological Institute, Houston, TX, USA
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10
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Common variants in genes of the postsynaptic FMRP signalling pathway are risk factors for autism spectrum disorders. Hum Genet 2014; 133:781-92. [PMID: 24442360 DOI: 10.1007/s00439-013-1416-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/25/2013] [Indexed: 10/25/2022]
Abstract
Autism spectrum disorders (ASD) are heterogeneous disorders with a high heritability and complex genetic architecture. Due to the central role of the fragile X mental retardation gene 1 protein (FMRP) pathway in ASD we investigated common functional variants of ASD risk genes regulating FMRP. We genotyped ten SNPs in two German patient sets (N = 192 and N = 254 families, respectively) and report association for rs7170637 (CYFIP1; set 1 and combined sets), rs6923492 (GRM1; combined sets), and rs25925 (CAMK4; combined sets). An additional risk score based on variants with an odds ratio (OR) >1.25 in set 1 and weighted by their respective log transmitted/untransmitted ratio revealed a significant effect (OR 1.30, 95 % CI 1.11-1.53; P = 0.0013) in the combined German sample. A subsequent meta-analysis including the two German samples, the "Strict/European" ASD subsample of the Autism Genome Project (1,466 families) and a French case/control (541/366) cohort showed again association of rs7170637-A (OR 0.85, 95 % CI 0.75-0.96; P = 0.007) and rs25925-G (OR 1.31, 95 % CI 1.04-1.64; P = 0.021) with ASD. Functional analyses revealed that these minor alleles predicted to alter splicing factor binding sites significantly increase levels of an alternative mRNA isoform of the respective gene while keeping the overall expression of the gene constant. These findings underpin the role of ASD candidate genes in postsynaptic FMRP regulation suggesting that an imbalance of specific isoforms of CYFIP1, an FMRP interaction partner, and CAMK4, a transcriptional regulator of the FMRP gene, modulates ASD risk. Both gene products are related to neuronal regulation of synaptic plasticity, a pathomechanism underlying ASD and may thus present future targets for pharmacological therapies in ASD.
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11
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Navarro D, Alvarado M, Morte B, Berbel D, Sesma J, Pacheco P, Morreale de Escobar G, Bernal J, Berbel P. Late maternal hypothyroidism alters the expression of Camk4 in neocortical subplate neurons: a comparison with Nurr1 labeling. Cereb Cortex 2013; 24:2694-706. [PMID: 23680840 DOI: 10.1093/cercor/bht129] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Maternal thyroid hormones (THs) are essential for normal offspring's neurodevelopment even after onset of fetal thyroid function. This is particularly relevant for preterm children who are deprived of maternal THs following birth, are at risk of suffering hypothyroxinemia, and develop attention-deficit/hyperactivity disorder. Expression of neocortical Ca(2+)/calmodulin kinase IV (Camk4), a genomic target of thyroid hormone, and nuclear receptor-related 1 protein (Nurr1), a postnatal marker of cortical subplate (SP) cells, was studied in euthyroid fetuses and in pups born to dams thyroidectomized in late gestation (LMH group, a model of prematurity), and compared with control and developmentally hypothyroid pups (C and MMI groups, respectively). In LMH pups, the extinction of heavy Camk4 expression in an SP was 1-2 days delayed postnatally compared with C pups. The heavy Camk4 and Nurr1 expression in the SP was prolonged in MMI pups, whereas heavy Camk4 and Nurr1 expression in layer VIb remains at P60. The abnormal expression of Camk4 in the cortical SP and in layer VIb might cause altered cortical connectivity affecting neocortical function.
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Affiliation(s)
- D Navarro
- Department Histology and Anatomy, Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
| | - M Alvarado
- Department Histology and Anatomy, Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz 91100, México
| | - B Morte
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid, Madrid, Spain Center for Biomedical Research on Rare Diseases (CIBERER), Madrid, Spain
| | - D Berbel
- Department Histology and Anatomy, Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
| | - J Sesma
- Department Histology and Anatomy, Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
| | - P Pacheco
- Instituto de Neuroetología, Universidad Veracruzana, Xalapa, Veracruz 91100, México
| | - G Morreale de Escobar
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid, Madrid, Spain Center for Biomedical Research on Rare Diseases (CIBERER), Madrid, Spain
| | - J Bernal
- Instituto de Investigaciones Biomédicas Alberto Sols, Consejo Superior de Investigaciones Científicas (CSIC) and Universidad Autónoma de Madrid, Madrid, Spain Center for Biomedical Research on Rare Diseases (CIBERER), Madrid, Spain
| | - P Berbel
- Department Histology and Anatomy, Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain
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12
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Wang H, Zhuo M. Group I metabotropic glutamate receptor-mediated gene transcription and implications for synaptic plasticity and diseases. Front Pharmacol 2012; 3:189. [PMID: 23125836 PMCID: PMC3485740 DOI: 10.3389/fphar.2012.00189] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 10/11/2012] [Indexed: 12/05/2022] Open
Abstract
Stimulation of group I metabotropic glutamate receptors (mGluRs) initiates a wide variety of signaling pathways. Group I mGluR activation can regulate gene expression at both translational and transcriptional levels, and induces translation or transcription-dependent synaptic plastic changes in neurons. The group I mGluR-mediated translation-dependent neural plasticity has been well reviewed. In this review, we will highlight group I mGluR-induced gene transcription and its role in synaptic plasticity. The signaling pathways (PKA, CaMKs, and MAPKs) which have been shown to link group I mGluRs to gene transcription, the relevant transcription factors (CREB and NF-κB), and target proteins (FMRP and ARC) will be documented. The significance and future direction for characterizing group I mGluR-mediated gene transcription in fragile X syndrome, schizophrenia, drug addiction, and other neurological disorders will also be discussed.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto Toronto, ON, Canada
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13
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Wang H, Morishita Y, Miura D, Naranjo JR, Kida S, Zhuo M. Roles of CREB in the regulation of FMRP by group I metabotropic glutamate receptors in cingulate cortex. Mol Brain 2012; 5:27. [PMID: 22867433 PMCID: PMC3478997 DOI: 10.1186/1756-6606-5-27] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/02/2012] [Indexed: 12/04/2022] Open
Abstract
Background Fragile X syndrome is caused by lack of fragile X mental retardation protein (FMRP) due to silencing of the FMR1 gene. The metabotropic glutamate receptors (mGluRs) in the central nervous system contribute to higher brain functions including learning/memory, mental disorders and persistent pain. The transcription factor cyclic AMP-responsive element binding protein (CREB) is involved in important neuronal functions, such as synaptic plasticity and neuronal survival. Our recent study has shown that stimulation of Group I mGluRs upregulated FMRP and activated CREB in anterior cingulate cortex (ACC), a key region for brain cognitive and executive functions, suggesting that activation of Group I mGluRs may upregulate FMRP through CREB signaling pathway. Results In this study, we demonstrate that CREB contributes to the regulation of FMRP by Group I mGluRs. In ACC neurons of adult mice overexpressing dominant active CREB mutant, the upregulation of FMRP by stimulating Group I mGluR is enhanced compared to wild-type mice. However, the regulation of FMRP by Group I mGluRs is not altered by overexpression of Ca2+-insensitive mutant form of downstream regulatory element antagonist modulator (DREAM), a transcriptional repressor involved in synaptic transmission and plasticity. Conclusion Our study has provided further evidence for CREB involvement in regulation of FMRP by Group I mGluRs in ACC neurons, and may help to elucidate the pathogenesis of fragile X syndrome.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, ON, M5S 1A8, Canada
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14
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Gross C, Berry-Kravis EM, Bassell GJ. Therapeutic strategies in fragile X syndrome: dysregulated mGluR signaling and beyond. Neuropsychopharmacology 2012; 37:178-95. [PMID: 21796106 PMCID: PMC3238060 DOI: 10.1038/npp.2011.137] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 06/17/2011] [Accepted: 06/17/2011] [Indexed: 01/11/2023]
Abstract
Fragile X syndrome (FXS) is an inherited neurodevelopmental disease caused by loss of function of the fragile X mental retardation protein (FMRP). In the absence of FMRP, signaling through group 1 metabotropic glutamate receptors is elevated and insensitive to stimulation, which may underlie many of the neurological and neuropsychiatric features of FXS. Treatment of FXS animal models with negative allosteric modulators of these receptors and preliminary clinical trials in human patients support the hypothesis that metabotropic glutamate receptor signaling is a valuable therapeutic target in FXS. However, recent research has also shown that FMRP may regulate diverse aspects of neuronal signaling downstream of several cell surface receptors, suggesting a possible new route to more direct disease-targeted therapies. Here, we summarize promising recent advances in basic research identifying and testing novel therapeutic strategies in FXS models, and evaluate their potential therapeutic benefits. We provide an overview of recent and ongoing clinical trials motivated by some of these findings, and discuss the challenges for both basic science and clinical applications in the continued development of effective disease mechanism-targeted therapies for FXS.
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Affiliation(s)
- Christina Gross
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Elizabeth M Berry-Kravis
- Departments of Pediatrics, Neurology, and Biochemistry, Rush University Medical Center, Chicago, IL, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
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15
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Santoro MR, Bray SM, Warren ST. Molecular mechanisms of fragile X syndrome: a twenty-year perspective. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 7:219-45. [PMID: 22017584 DOI: 10.1146/annurev-pathol-011811-132457] [Citation(s) in RCA: 377] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Fragile X syndrome (FXS) is a common form of inherited intellectual disability and is one of the leading known causes of autism. The mutation responsible for FXS is a large expansion of the trinucleotide CGG repeat in the 5' untranslated region of the X-linked gene FMR1. This expansion leads to DNA methylation of FMR1 and to transcriptional silencing, which results in the absence of the gene product, FMRP, a selective messenger RNA (mRNA)-binding protein that regulates the translation of a subset of dendritic mRNAs. FMRP is critical for mGluR (metabotropic glutamate receptor)-dependent long-term depression, as well as for other forms of synaptic plasticity; its absence causes excessive and persistent protein synthesis in postsynaptic dendrites and dysregulated synaptic function. Studies continue to refine our understanding of FMRP's role in synaptic plasticity and to uncover new functions of this protein, which have illuminated therapeutic approaches for FXS.
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Affiliation(s)
- Michael R Santoro
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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16
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Wang H, Xu H, Wu LJ, Kim SS, Chen T, Koga K, Descalzi G, Gong B, Vadakkan KI, Zhang X, Kaang BK, Zhuo M. Identification of an adenylyl cyclase inhibitor for treating neuropathic and inflammatory pain. Sci Transl Med 2011; 3:65ra3. [PMID: 21228397 DOI: 10.1126/scitranslmed.3001269] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Neuropathic pain, often caused by nerve injury, is commonly observed among patients with different diseases. Because its basic mechanisms are poorly understood, effective medications are limited. Previous investigations of basic pain mechanisms and drug discovery efforts have focused mainly on early sensory neurons such as dorsal root ganglion and spinal dorsal horn neurons, and few synaptic-level studies or new drugs are designed to target the injury-related cortical plasticity that accompanies neuropathic pain. Our previous work has demonstrated that calcium-stimulated adenylyl cyclase 1 (AC1) is critical for nerve injury-induced synaptic changes in the anterior cingulate cortex. Through rational drug design and chemical screening, we have identified a lead candidate AC1 inhibitor, NB001, which is relatively selective for AC1 over other adenylate cyclase isoforms. Using a variety of behavioral tests and toxicity studies, we have found that NB001, when administered intraperitoneally or orally, has an analgesic effect in animal models of neuropathic pain, without any apparent side effects. Our study thus shows that AC1 could be a productive therapeutic target for neuropathic pain and describes a new agent for the possible treatment of neuropathic pain.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto Centre for the Study of Pain, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada
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17
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Evidence of mitochondrial dysfunction in fragile X-associated tremor/ataxia syndrome. Biochem J 2010; 429:545-52. [PMID: 20513237 DOI: 10.1042/bj20091960] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
FXTAS (fragile X-associated tremor/ataxia syndrome) is a late-onset neurodegenerative disorder that affects individuals who are carriers of premutation expansions (55-200 CGG repeats) in the 5' untranslated region of the FMR1 (fragile X mental retardation 1) gene. The role of MD (mitochondrial dysfunction) in FXTAS was evaluated in fibroblasts and brain samples from premutation carriers with and without FXTAS symptoms, with a range of CGG repeats. This study resulted in several important conclusions: (i) decreased NAD- and FAD-linked oxygen uptake rates and uncoupling between electron transport and synthesis of ATP were observed in fibroblasts from premutation carriers; (ii) a lower expression of mitochondrial proteins preceded both in age and in CGG repeats the appearance of overt clinical involvement; (iii) the CGG repeat size required for altered mitochondrial protein expression was also smaller than that required to produce brain intranuclear inclusions from individuals with the premutation who died, suggesting that MD is an incipient pathological process occurring in individuals who do not display overt features of FXTAS; and (iv) on the basis of the CGG repeats, MD preceded the increase in oxidative/nitrative stress damage, indicating that the latter is a late event. MD in carriers of small CGG repeats, even when the allele size is not sufficient to produce FXTAS, may predispose them to other disorders (e.g. Parkinson's disease) that are likely to involve MD, and to environmental stressors, which may trigger the development of FXTAS symptoms. Detection of MD is of critical importance to the management of FXTAS, since it opens up additional treatment options for this disorder.
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Wang H, Kim SS, Zhuo M. Roles of fragile X mental retardation protein in dopaminergic stimulation-induced synapse-associated protein synthesis and subsequent alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) receptor internalization. J Biol Chem 2010; 285:21888-901. [PMID: 20457613 DOI: 10.1074/jbc.m110.116293] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fragile X syndrome, the most common form of inherited mental retardation, is caused by the absence of the RNA-binding protein fragile X mental retardation protein (FMRP). FMRP regulates local protein synthesis in dendritic spines. Dopamine (DA) is involved in the modulation of synaptic plasticity. Activation of DA receptors can regulate higher brain functions in a protein synthesis-dependent manner. Our recent study has shown that FMRP acts as a key messenger for DA modulation in forebrain neurons. Here, we demonstrate that FMRP is critical for DA D1 receptor-mediated synthesis of synapse-associated protein 90/PSD-95-associated protein 3 (SAPAP3) in the prefrontal cortex (PFC). DA D1 receptor stimulation induced dynamic changes of FMRP phosphorylation. The changes in FMRP phosphorylation temporally correspond with the expression of SAPAP3 after D1 receptor stimulation. Protein phosphatase 2A, ribosomal protein S6 kinase, and mammalian target of rapamycin are the key signaling molecules for FMRP linking DA D1 receptors to SAPAP3. Knockdown of SAPAP3 did not affect surface expression of alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-4-propionate (AMPA) GluR1 receptors induced by D1 receptor activation but impaired their subsequent internalization in cultured PFC neurons; the subsequent internalization of GluR1 was also impaired in Fmr1 knock-out PFC neurons, suggesting that FMRP may be involved in subsequent internalization of GluR1 through regulating the abundance of SAPAP3 after DA D1 receptor stimulation. Our study thus provides further insights into FMRP involvement in DA modulation and may help to reveal the molecular mechanisms underlying impaired learning and memory in fragile X syndrome.
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Affiliation(s)
- Hansen Wang
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Mercaldo V, Descalzi G, Zhuo M. Fragile X mental retardation protein in learning-related synaptic plasticity. Mol Cells 2009; 28:501-7. [PMID: 20047076 DOI: 10.1007/s10059-009-0193-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 12/09/2009] [Indexed: 01/13/2023] Open
Abstract
Fragile X syndrome (FXS) is caused by a lack of the fragile X mental retardation protein (FMRP) due to silencing of the Fmr1 gene. As an RNA binding protein, FMRP is thought to contribute to synaptic plasticity by regulating plasticity-related protein synthesis and other signaling pathways. Previous studies have mostly focused on the roles of FMRP within the hippocampus--a key structure for spatial memory. However, recent studies indicate that FMRP may have a more general contribution to brain functions, including synaptic plasticity and modulation within the prefrontal cortex. In this brief review, we will focus on recent studies reported in the prefrontal cortex, including the anterior cingulate cortex (ACC). We hypothesize that alterations in ACC-related plasticity and synaptic modulation may contribute to various forms of cognitive deficits associated with FXS.
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Affiliation(s)
- Valentina Mercaldo
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada
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Shang Y, Wang H, Mercaldo V, Li X, Chen T, Zhuo M. Fragile X mental retardation protein is required for chemically-induced long-term potentiation of the hippocampus in adult mice. J Neurochem 2009; 111:635-46. [PMID: 19659572 DOI: 10.1111/j.1471-4159.2009.06314.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Fragile X syndrome (FXS), a common form of inherited mental retardation, is caused by the lack of fragile X mental retardation protein (FMRP). The animal model of FXS, Fmr1 knockout mice, have deficits in the Morris water maze and trace fear memory tests, showing impairment in hippocampus-dependent learning and memory. However, results for synaptic long-term potentiation (LTP), a key cellular model for learning and memory, remain inconclusive in the hippocampus of Fmr1 knockout mice. Here, we demonstrate that FMRP is required for glycine induced LTP (Gly-LTP) in the CA1 of hippocampus. This form of LTP requires activation of post-synaptic NMDA receptors and metabotropic glutamateric receptors, as well as the subsequent activation of extracellular signal-regulated kinase (ERK) 1/2. However, paired-pulse facilitation was not affected by glycine treatment. Genetic deletion of FMRP interrupted the phosphorylation of ERK1/2, suggesting the possible role of FMRP in the regulation of the activity of ERK1/2. Our study provide strong evidences that FMRP participates in Gly-LTP in the hippocampus by regulating the phosphorylation of ERK1/2, and that improper regulation of these signaling pathways may contribute to the learning and memory deficits observed in FXS.
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Affiliation(s)
- Yuze Shang
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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