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Dias CM, Issac B, Sun L, Lukowicz A, Talukdar M, Akula SK, Miller MB, Walsh K, Rockowitz S, Walsh CA. Glial dysregulation in the human brain in fragile X-associated tremor/ataxia syndrome. Proc Natl Acad Sci U S A 2023; 120:e2300052120. [PMID: 37252957 PMCID: PMC10265985 DOI: 10.1073/pnas.2300052120] [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: 01/05/2023] [Accepted: 04/03/2023] [Indexed: 06/01/2023] Open
Abstract
Short trinucleotide expansions at the FMR1 locus are associated with the late-onset condition fragile X-associated tremor/ataxia syndrome (FXTAS), which shows very different clinical and pathological features from fragile X syndrome (associated with longer expansions), with no clear molecular explanation for these marked differences. One prevailing theory posits that the shorter, premutation expansion uniquely causes extreme neurotoxic increases in FMR1 mRNA (i.e., four to eightfold increases), but evidence to support this hypothesis is largely derived from analysis of peripheral blood. We applied single-nucleus RNA sequencing to postmortem frontal cortex and cerebellum from 7 individuals with premutation and matched controls (n = 6) to assess cell type-specific molecular neuropathology. We found only modest upregulation (~1.3-fold) of FMR1 in some glial populations associated with premutation expansions. In premutation cases, we also identified decreased astrocyte proportions in the cortex. Differential expression and gene ontology analysis demonstrated altered neuroregulatory roles of glia. Using network analyses, we identified cell type-specific and region-specific patterns of FMR1 protein target gene dysregulation unique to premutation cases, with notable network dysregulation in the cortical oligodendrocyte lineage. We used pseudotime trajectory analysis to determine how oligodendrocyte development was altered and identified differences in early gene expression in oligodendrocyte trajectories in premutation cases specifically, implicating early cortical glial developmental perturbations. These findings challenge dogma regarding extremely elevated FMR1 increases in FXTAS and implicate glial dysregulation as a critical facet of premutation pathophysiology, representing potential unique therapeutic targets directly derived from the human condition.
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Affiliation(s)
- Caroline M. Dias
- Division of Developmental Medicine, Boston Children’s Hospital, Boston, MA02115
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Department of Pediatrics, Harvard Medical School, Boston, MA02115
- Department of Pediatrics, Section of Developmental Pediatrics, Section of Genetics and Metabolism, and Denver Fragile X Clinic and Research Center, Children’s Hospital Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Biju Issac
- Research Computing, Department of Information Technology, Boston Children’s Hospital, Boston, MA02115
| | - Liang Sun
- Research Computing, Department of Information Technology, Boston Children’s Hospital, Boston, MA02115
| | - Abigail Lukowicz
- Department of Pediatrics, Section of Developmental Pediatrics, Section of Genetics and Metabolism, and Denver Fragile X Clinic and Research Center, Children’s Hospital Colorado, University of Colorado Anschutz Medical Campus, Aurora, CO80045
| | - Maya Talukdar
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Harvard-Massachusetts Institute of Technology MD/PhD Program, Program in Bioinformatics & Integrative Genomics, Harvard Medical School, Boston, MA02115
| | - Shyam K. Akula
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Harvard-Massachusetts Institute of Technology MD/PhD Program, Program in Neuroscience, Harvard Medical School, Boston, MA02115
| | - Michael B. Miller
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Department of Pathology, Brigham and Women’s Hospital, Boston, MA02115
| | - Katherine Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
| | - Shira Rockowitz
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Research Computing, Department of Information Technology, Boston Children’s Hospital, Boston, MA02115
| | - Christopher A. Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Boston Children’s Hospital, Boston, MA02115
- Department of Pediatrics, Harvard Medical School, Boston, MA02115
- HHMI, Boston Children’s Hospital, Boston, MA02115
- Department of Neurology, Harvard Medical School, Boston, MA02115
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2
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Dulman RS, Auta J, Wandling GM, Patwell R, Zhang H, Pandey SC. Persistence of cerebellar ataxia during chronic ethanol exposure is associated with epigenetic up-regulation of Fmr1 gene expression in rat cerebellum. Alcohol Clin Exp Res 2021; 45:2006-2016. [PMID: 34453331 PMCID: PMC8602769 DOI: 10.1111/acer.14691] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Revised: 07/31/2021] [Accepted: 08/03/2021] [Indexed: 01/25/2023]
Abstract
BACKGROUND Alcohol intoxication produces ataxia by affecting the cerebellum, which coordinates movements. Fragile X mental retardation (FMR) protein is a complex regulator of RNA and synaptic plasticity implicated in fragile X-associated tremor/ataxia syndrome, which features ataxia and increased Fmr1 mRNA expression resulting from epigenetic dysregulation of FMRP. We recently demonstrated that acute ethanol-induced ataxia is associated with increased cerebellar Fmr1 gene expression via histone modifications in rats, but it is unknown whether similar behavioral and molecular changes occur following chronic ethanol exposure. Here, we investigated the effects of chronic ethanol exposure on ataxia and epigenetically regulated changes in Fmr1 expression in the cerebellum. METHODS Male adult Sprague-Dawley rats were trained on the accelerating rotarod and then fed with chronic ethanol or a control Lieber-DeCarli diet while undergoing periodic behavioral testing for ataxia during ethanol exposure and withdrawal. Cerebellar tissues were analyzed for expression of the Fmr1 gene and its targets using a real-time quantitative polymerase chain reaction assay. The epigenetic regulation of Fmr1 was also investigated using a chromatin immunoprecipitation assay. RESULTS Ataxic behavior measured by the accelerating rotarod behavioral test developed during chronic ethanol treatment and persisted at both the 8-h and 24-h withdrawal time points compared to control diet-fed rats. In addition, chronic ethanol treatment resulted in up-regulated expression of Fmr1 mRNA and increased activating epigenetic marks H3K27 acetylation and H3K4 trimethylation at 2 sites within the Fmr1 promoter. Finally, measurement of the expression of relevant FMRP mRNA targets in the cerebellum showed that chronic ethanol up-regulated cAMP response element binding (CREB) Creb1, Psd95, Grm5, and Grin2b mRNA expression without altering Grin2a, Eaa1, or histone acetyltransferases CREB binding protein (Cbp) or p300 mRNA transcripts. CONCLUSIONS These results suggest that epigenetic regulation of Fmr1 and subsequent FMRP regulation of target mRNA transcripts constitute neuroadaptations in the cerebellum that may underlie the persistence of ataxic behavior during chronic ethanol exposure and withdrawal.
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Affiliation(s)
- Russell S. Dulman
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
| | - James Auta
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
| | - Gabriela M. Wandling
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
| | - Ryan Patwell
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
| | - Huaibo Zhang
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
- Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, 60612 USA
| | - Subhash C. Pandey
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois, 60612 USA
- Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois, 60612 USA
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3
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Holm KN, Herren AW, Taylor SL, Randol JL, Kim K, Espinal G, Martiínez-Cerdeño V, Pessah IN, Hagerman RJ, Hagerman PJ. Human Cerebral Cortex Proteome of Fragile X-Associated Tremor/Ataxia Syndrome. Front Mol Biosci 2021; 7:600840. [PMID: 33585555 PMCID: PMC7879451 DOI: 10.3389/fmolb.2020.600840] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/27/2020] [Indexed: 01/10/2023] Open
Abstract
Background: Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder associated with premutation CGG-repeat expansions (55–200 repeats) in the 5′ non-coding portion of the fragile X mental retardation 1 (FMR1) gene. Core features of FXTAS include progressive tremor/ataxia, cognitive decline, variable brain volume loss, and white matter disease. The principal histopathological feature of FXTAS is the presence of central nervous system (CNS) and non-CNS intranuclear inclusions. Objective: To further elucidate the molecular underpinnings of FXTAS through the proteomic characterization of human FXTAS cortexes. Results: Proteomic analysis of FXTAS brain cortical tissue (n = 8) identified minor differences in protein abundance compared to control brains (n = 6). Significant differences in FXTAS relative to control brain predominantly involved decreased abundance of proteins, with the greatest decreases observed for tenascin-C (TNC), cluster of differentiation 38 (CD38), and phosphoserine aminotransferase 1 (PSAT1); proteins typically increased in other neurodegenerative diseases. Proteins with the greatest increased abundance include potentially novel neurodegeneration-related proteins and small ubiquitin-like modifier 1/2 (SUMO1/2). The FMRpolyG peptide, proposed in models of FXTAS pathogenesis but only identified in trace amounts in the earlier study of FXTAS inclusions, was not identified in any of the FXTAS or control brains in the current study. Discussion: The observed proteomic shifts, while generally relatively modest, do show a bias toward decreased protein abundance with FXTAS. Such shifts in protein abundance also suggest altered RNA binding as well as loss of cell–cell adhesion/structural integrity. Unlike other neurodegenerative diseases, the proteome of end-stage FXTAS does not suggest a strong inflammation-mediated degenerative response.
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Affiliation(s)
- Katharine Nichole Holm
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Davis, CA, United States
| | - Anthony W Herren
- Mass Spectrometry Research Core, University of California Davis, Davis, CA, United States
| | - Sandra L Taylor
- Department of Public Health Sciences, Division of Biostatistics, University of California Davis School of Medicine, Davis, CA, United States
| | - Jamie L Randol
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Davis, CA, United States
| | - Kyoungmi Kim
- Department of Public Health Sciences, Division of Biostatistics, University of California Davis School of Medicine, Davis, CA, United States.,Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis School of Medicine, Davis, CA, United States
| | - Glenda Espinal
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Davis, CA, United States
| | - Verónica Martiínez-Cerdeño
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis School of Medicine, Davis, CA, United States.,Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Davis, CA, United States
| | - Isaac N Pessah
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis School of Medicine, Davis, CA, United States.,Department of Molecular Biosciences, University of California Davis School of Veterinary Medicine, Davis, CA, United States
| | - Randi J Hagerman
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis School of Medicine, Davis, CA, United States.,Department of Pediatrics, University of California Davis School of Medicine, Davis, CA, United States
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Davis, CA, United States.,Medical Investigation of Neurodevelopmental Disorders Institute, University of California Davis School of Medicine, Davis, CA, United States
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4
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Li W, Kutas M, Gray JA, Hagerman RH, Olichney JM. The Role of Glutamate in Language and Language Disorders - Evidence from ERP and Pharmacologic Studies. Neurosci Biobehav Rev 2020; 119:217-241. [PMID: 33039453 DOI: 10.1016/j.neubiorev.2020.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/10/2020] [Accepted: 09/21/2020] [Indexed: 12/31/2022]
Abstract
Current models of language processing do not address mechanisms at the neurotransmitter level, nor how pharmacologic agents may improve language function(s) in seemingly disparate disorders. L-Glutamate, the primary excitatory neurotransmitter in the human brain, is extensively involved in various higher cortical functions. We postulate that the physiologic role of L-Glutamate neurotransmission extends to the regulation of language access, comprehension, and production, and that disorders in glutamatergic transmission and circuitry contribute to the pathogenesis of neurodegenerative diseases and sporadic-onset language disorders such as the aphasic stroke syndromes. We start with a review of basic science data pertaining to various glutamate receptors in the CNS and ways that they may influence the physiological processes of language access and comprehension. We then focus on the dysregulation of glutamate neurotransmission in three conditions in which language dysfunction is prominent: Alzheimer's Disease, Fragile X-associated Tremor/Ataxia Syndrome, and Aphasic Stroke Syndromes. Finally, we review the pharmacologic and electrophysiologic (event related brain potential or ERP) data pertaining to the role glutamate neurotransmission plays in language processing and disorders.
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Affiliation(s)
- Wentao Li
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA.
| | - Marta Kutas
- Department of Cognitive Science, University of California, San Diego, 9500 Gilman Drive #0515, La Jolla, CA, 92093, USA; Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - John A Gray
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA, 95618, USA.
| | - Randi H Hagerman
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA, 95817, USA.
| | - John M Olichney
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA, 95618, USA.
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5
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Brašić JR, Nandi A, Russell DS, Jennings D, Barret O, Mathur A, Slifer K, Sedlak T, Martin SD, Brinson Z, Vyas P, Seibyl JP, Berry-Kravis EM, Wong DF, Budimirovic DB. Reduced Expression of Cerebral Metabotropic Glutamate Receptor Subtype 5 in Men with Fragile X Syndrome. Brain Sci 2020; 10:E899. [PMID: 33255214 PMCID: PMC7760509 DOI: 10.3390/brainsci10120899] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/07/2020] [Accepted: 11/14/2020] [Indexed: 12/28/2022] Open
Abstract
Glutamatergic receptor expression is mostly unknown in adults with fragile X syndrome (FXS). Favorable behavioral effects of negative allosteric modulators (NAMs) of the metabotropic glutamate receptor subtype 5 (mGluR5) in fmr1 knockout (KO) mouse models have not been confirmed in humans with FXS. Measurement of cerebral mGluR5 expression in humans with FXS exposed to NAMs might help in that effort. We used positron emission tomography (PET) to measure the mGluR5 density as a proxy of mGluR5 expression in cortical and subcortical brain regions to confirm target engagement of NAMs for mGluR5s. The density and the distribution of mGluR5 were measured in two independent samples of men with FXS (N = 9) and typical development (TD) (N = 8). We showed the feasibility of this complex study including MRI and PET, meaning that this challenging protocol can be accomplished in men with FXS with an adequate preparation. Analysis of variance of estimated mGluR5 expression showed that mGluR5 expression was significantly reduced in cortical and subcortical regions of men with FXS in contrast to age-matched men with TD.
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Affiliation(s)
- James R. Brašić
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Ayon Nandi
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - David S. Russell
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
| | - Danna Jennings
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
- Denali Therapeutics, Inc., South San Francisco, CA 94080, USA
| | - Olivier Barret
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
| | - Anil Mathur
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Keith Slifer
- Department of Psychiatry and Behavioral Sciences-Child Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Department of Behavioral Psychology, Kennedy Krieger Institute, Baltimore, MD 21205, USA
| | - Thomas Sedlak
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Department of Psychiatry and Behavioral Sciences-General Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Samuel D. Martin
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Department of Neuroscience, Zanvyl Krieger School of Arts and Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Zabecca Brinson
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - Pankhuri Vyas
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
| | - John P. Seibyl
- Clinical Research, Institute for Neurodegenerative Disorders, New Haven, CT 06510, USA; (D.S.R.); (D.J.); (O.B.); (J.P.S.)
- Research Clinic, Invicro LLC, New Haven, CT 06510, USA
| | - Elizabeth M. Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, and Biochemistry, Rush University Medical Center, Chicago, IL 60612, USA;
| | - Dean F. Wong
- Section of High Resolution Brain Positron Emission Tomography Imaging, Division of Nuclear Medicine and Molecular Imaging, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (A.N.); (A.M.); (T.S.); (S.D.M.); (Z.B.); (P.V.); (D.F.W.)
- Precision Radio-Theranostics Translational Laboratories, Mallinckrodt Institute of Radiology, School of Medicine, Washington University, Saint Louis, MO 63110, USA
| | - Dejan B. Budimirovic
- Department of Psychiatry and Behavioral Sciences-Child Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Departments of Psychiatry and Neurogenetics, Kennedy Krieger Institute, Baltimore, MD 21205, USA
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6
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Cao Y, Peng Y, Kong HE, Allen EG, Jin P. Metabolic Alterations in FMR1 Premutation Carriers. Front Mol Biosci 2020; 7:571092. [PMID: 33195417 PMCID: PMC7531624 DOI: 10.3389/fmolb.2020.571092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/26/2020] [Indexed: 12/15/2022] Open
Abstract
FMR1 gene premutation carriers are at risk of developing Fragile X-associated tremor/ataxia syndrome (FXTAS) and Fragile X-associated primary ovarian insufficiency (FXPOI) in adulthood. Currently the development of biomarkers and effective treatments in FMR1 premutations is still in its infancy. Recent metabolic studies have shown novel findings in asymptomatic FMR1 premutation carriers and FXTAS, which provide promising insight through identification of potential biomarkers and therapeutic pathways. Here we review the latest advancements of the metabolic alterations found in asymptomatic FMR1 premutation carriers and FXTAS, along with our perspective for future studies in this emerging field.
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Affiliation(s)
- Yiqu Cao
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Yun Peng
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Ha Eun Kong
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
| | - Emily G Allen
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
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7
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Malik AR, Willnow TE. Excitatory Amino Acid Transporters in Physiology and Disorders of the Central Nervous System. Int J Mol Sci 2019; 20:ijms20225671. [PMID: 31726793 PMCID: PMC6888459 DOI: 10.3390/ijms20225671] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 11/07/2019] [Accepted: 11/11/2019] [Indexed: 12/12/2022] Open
Abstract
Excitatory amino acid transporters (EAATs) encompass a class of five transporters with distinct expression in neurons and glia of the central nervous system (CNS). EAATs are mainly recognized for their role in uptake of the amino acid glutamate, the major excitatory neurotransmitter. EAATs-mediated clearance of glutamate released by neurons is vital to maintain proper glutamatergic signalling and to prevent toxic accumulation of this amino acid in the extracellular space. In addition, some EAATs also act as chloride channels or mediate the uptake of cysteine, required to produce the reactive oxygen speciesscavenger glutathione. Given their central role in glutamate homeostasis in the brain, as well as their additional activities, it comes as no surprise that EAAT dysfunctions have been implicated in numerous acute or chronic diseases of the CNS, including ischemic stroke and epilepsy, cerebellar ataxias, amyotrophic lateral sclerosis, Alzheimer’s disease and Huntington’s disease. Here we review the studies in cellular and animal models, as well as in humans that highlight the roles of EAATs in the pathogenesis of these devastating disorders. We also discuss the mechanisms regulating EAATs expression and intracellular trafficking and new exciting possibilities to modulate EAATs and to provide neuroprotection in course of pathologies affecting the CNS.
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Affiliation(s)
- Anna R. Malik
- Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
- Correspondence:
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8
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Dulman RS, Auta J, Teppen T, Pandey SC. Acute Ethanol Produces Ataxia and Induces Fmr1 Expression via Histone Modifications in the Rat Cerebellum. Alcohol Clin Exp Res 2019; 43:1191-1198. [PMID: 30969437 DOI: 10.1111/acer.14044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/04/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND The cerebellum is fundamental for motor coordination and therefore crucial in ethanol (EtOH)-induced ataxia. EtOH contributes to cerebellar pathophysiology. Fragile-X mental retardation protein (FMRP) is a complex regulator of RNA and synaptic plasticity implicated in fragile-X tremor and ataxia syndrome, a phenotype featuring increased Fmr1 mRNA expression. Recent studies have implicated glutamatergic targets of FMRP in hereditary cerebellar ataxias including the main cerebellar excitatory amino acid (Eaa1) transporter and a subtype of metabotropic glutamate receptor (Grm5). However, EtOH-induced changes in cerebellar Fmr1 expression and its epigenetic regulation have not been investigated. Here, we examined the effects of acute EtOH exposure on ataxic behavior, gene expression, and epigenetic regulation of the Fmr1 gene and its glutamatergic targets in the rat cerebellum. METHODS Male adult Sprague Dawley rats received acute EtOH (2 g/kg) intraperitoneally 1 hour prior to ataxic behavioral testing on the accelerating rotarod and were sacrificed immediately thereafter. Cerebellar tissues were analyzed for gene expression and epigenetic regulation of the Fmr1 gene and its glutamatergic targets in the rat cerebellum using real-time quantitative polymerase chain reaction (PCR) and chromatin immunoprecipitation. RESULTS Acute EtOH exposure caused marked ataxia on the accelerating rotarod test compared with saline-treated controls. This ataxic response was associated with increases in mRNA levels of Fmr1, postsynaptic density 95 (Psd95), Eaa1, and Grm5 in the cerebellum. In addition, we found increased H3K27 acetylation both at the promoter region of Fmr1 and at a proposed cyclic adenosine monophosphate (cAMP) response-element binding (CREB) site downstream of the Fmr1 transcription start site. Furthermore, acute EtOH exposure significantly increased Creb1 and the histone acetyltransferases (HAT) CREB binding protein (Cbp), and p300 mRNA transcripts. CONCLUSIONS Overall, EtOH regulates cerebellar Fmr1 expression most likely via HAT-mediated increase in histone acetylation. We propose that FMRP regulation of glutamatergic transcripts plays an important role in disrupting the excitatory-inhibitory balance in the cerebellum underlying EtOH-induced ataxia.
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Affiliation(s)
- Russell S Dulman
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois
| | - James Auta
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois
| | - Tara Teppen
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Subhash C Pandey
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois.,Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
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9
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Conditional Knock-out of mGluR5 from Astrocytes during Epilepsy Development Impairs High-Frequency Glutamate Uptake. J Neurosci 2018; 39:727-742. [PMID: 30504280 DOI: 10.1523/jneurosci.1148-18.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 11/11/2018] [Accepted: 11/18/2018] [Indexed: 11/21/2022] Open
Abstract
Astrocyte expression of metabotropic glutamate receptor 5 (mGluR5) is consistently observed in resected tissue from patients with epilepsy and is equally prevalent in animal models of epilepsy. However, little is known about the functional signaling properties or downstream consequences of astrocyte mGluR5 activation during epilepsy development. In the rodent brain, astrocyte mGluR5 expression is developmentally regulated and confined in expression/function to the first weeks of life, with similar observations made in human control tissue. Herein, we demonstrate that mGluR5 expression and function dramatically increase in a mouse model of temporal lobe epilepsy. Interestingly, in both male and female mice, mGluR5 function persists in the astrocyte throughout the process of epileptogenesis following status epilepticus. However, mGluR5 expression and function are transient in animals that do not develop epilepsy over an equivalent time period, suggesting that patterns of mGluR5 expression may signify continuing epilepsy development or its resolution. We demonstrate that, during epileptogenesis, astrocytes reacquire mGluR5-dependent calcium transients following agonist application or synaptic glutamate release, a feature of astrocyte-neuron communication absent since early development. Finally, we find that the selective and conditional knock-out of mGluR5 signaling from astrocytes during epilepsy development slows the rate of glutamate clearance through astrocyte glutamate transporters under high-frequency stimulation conditions, a feature that suggests astrocyte mGluR5 expression during epileptogenesis may recapitulate earlier developmental roles in regulating glutamate transporter function.SIGNIFICANCE STATEMENT In development, astrocyte mGluR5 signaling plays a critical role in regulating structural and functional interactions between astrocytes and neurons at the tripartite synapse. Notably, mGluR5 signaling is a positive regulator of astrocyte glutamate transporter expression and function, an essential component of excitatory signaling regulation in hippocampus. After early development, astrocyte mGluR5 expression is downregulated, but reemerges in animal models of temporal lobe epilepsy (TLE) development and patient epilepsy samples. We explored the hypothesis that astrocyte mGluR5 reemergence recapitulates earlier developmental roles during TLE acquisition. Our work demonstrates that astrocytes with mGluR5 signaling during TLE development perform faster glutamate uptake in hippocampus, revealing a previously unexplored role for astrocyte mGluR5 signaling in hypersynchronous pathology.
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Hagerman RJ, Protic D, Rajaratnam A, Salcedo-Arellano MJ, Aydin EY, Schneider A. Fragile X-Associated Neuropsychiatric Disorders (FXAND). Front Psychiatry 2018; 9:564. [PMID: 30483160 PMCID: PMC6243096 DOI: 10.3389/fpsyt.2018.00564] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Accepted: 10/18/2018] [Indexed: 12/12/2022] Open
Abstract
Fragile X syndrome (FXS) is caused by the full mutation (>200 CGG repeats) in the Fragile X Mental Retardation 1 (FMR1) gene. It is the most common inherited cause of intellectual disability (ID) and autism. This review focuses on neuropsychiatric disorders frequently experienced by premutation carriers with 55 to 200 CGG repeats and the pathophysiology involves elevated FMR1 mRNA levels, which is different from the absence or deficiency of fragile X mental retardation protein (FMRP) seen in FXS. Neuropsychiatric disorders are the most common problems associated with the premutation, and they affect approximately 50% of individuals with 55 to 200 CGG repeats in the FMR1 gene. Neuropsychiatric disorders in children with the premutation include anxiety, ADHD, social deficits, or autism spectrum disorders (ASD). In adults with the premutation, anxiety and depression are the most common problems, although obsessive compulsive disorder, ADHD, and substance abuse are also common. These problems are often exacerbated by chronic fatigue, chronic pain, fibromyalgia, autoimmune disorders and sleep problems, which are also associated with the premutation. Here we review the clinical studies, neuropathology and molecular underpinnings of RNA toxicity associated with the premutation. We also propose the name Fragile X-associated Neuropsychiatric Disorders (FXAND) in an effort to promote research and the use of fragile X DNA testing to enhance recognition and treatment for these disorders.
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Affiliation(s)
- Randi J. Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, United States
| | - Dragana Protic
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Akash Rajaratnam
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Case Western Reserve University School of Medicine, Cleveland, OH, United States
| | - Maria J. Salcedo-Arellano
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, United States
| | - Elber Yuksel Aydin
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Andrea Schneider
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Sacramento, CA, United States
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, United States
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11
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mGlu1 Receptors Monopolize the Synaptic Control of Cerebellar Purkinje Cells by Epigenetically Down-Regulating mGlu5 Receptors. Sci Rep 2018; 8:13361. [PMID: 30190524 PMCID: PMC6127335 DOI: 10.1038/s41598-018-31369-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/09/2018] [Indexed: 11/10/2022] Open
Abstract
In cerebellar Purkinje cells (PCs) type-1 metabotropic glutamate (mGlu1) receptors play a key role in motor learning and drive the refinement of synaptic innervation during postnatal development. The cognate mGlu5 receptor is absent in mature PCs and shows low expression levels in the adult cerebellar cortex. Here we found that mGlu5 receptors were heavily expressed by PCs in the early postnatal life, when mGlu1α receptors were barely detectable. The developmental decline of mGlu5 receptors coincided with the appearance of mGlu1α receptors in PCs, and both processes were associated with specular changes in CpG methylation in the corresponding gene promoters. It was the mGlu1 receptor that drove the elimination of mGlu5 receptors from PCs, as shown by data obtained with conditional mGlu1α receptor knockout mice and with targeted pharmacological treatments during critical developmental time windows. The suppressing activity of mGlu1 receptors on mGlu5 receptor was maintained in mature PCs, suggesting that expression of mGlu1α and mGlu5 receptors is mutually exclusive in PCs. These findings add complexity to the the finely tuned mechanisms that regulate PC biology during development and in the adult life and lay the groundwork for an in-depth analysis of the role played by mGlu5 receptors in PC maturation.
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Perkins EM, Clarkson YL, Suminaite D, Lyndon AR, Tanaka K, Rothstein JD, Skehel PA, Wyllie DJA, Jackson M. Loss of cerebellar glutamate transporters EAAT4 and GLAST differentially affects the spontaneous firing pattern and survival of Purkinje cells. Hum Mol Genet 2018; 27:2614-2627. [PMID: 29741614 PMCID: PMC6049029 DOI: 10.1093/hmg/ddy169] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 04/30/2018] [Accepted: 05/01/2018] [Indexed: 12/20/2022] Open
Abstract
Loss of excitatory amino acid transporters (EAATs) has been implicated in a number of human diseases including spinocerebellar ataxias, Alzhiemer's disease and motor neuron disease. EAAT4 and GLAST/EAAT1 are the two predominant EAATs responsible for maintaining low extracellular glutamate levels and preventing neurotoxicity in the cerebellum, the brain region essential for motor control. Here using genetically modified mice we identify new critical roles for EAAT4 and GLAST/EAAT1 as modulators of Purkinje cell (PC) spontaneous firing patterns. We show high EAAT4 levels, by limiting mGluR1 signalling, are essential in constraining inherently heterogeneous firing of zebrin-positive PCs. Moreover mGluR1 antagonists were found to restore regular spontaneous PC activity and motor behaviour in EAAT4 knockout mice. In contrast, GLAST/EAAT1 expression is required to sustain normal spontaneous simple spike activity in low EAAT4 expressing (zebrin-negative) PCs by restricting NMDA receptor activation. Blockade of NMDA receptor activity restores spontaneous activity in zebrin-negative PCs of GLAST knockout mice and furthermore alleviates motor deficits. In addition both transporters have differential effects on PC survival, with zebrin-negative PCs more vulnerable to loss of GLAST/EAAT1 and zebrin-positive PCs more vulnerable to loss of EAAT4. These findings reveal that glutamate transporter dysfunction through elevated extracellular glutamate and the aberrant activation of extrasynaptic receptors can disrupt cerebellar output by altering spontaneous PC firing. This expands our understanding of disease mechanisms in cerebellar ataxias and establishes EAATs as targets for restoring homeostasis in a variety of neurological diseases where altered cerebellar output is now thought to play a key role in pathogenesis.
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Affiliation(s)
- Emma M Perkins
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Yvonne L Clarkson
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Daumante Suminaite
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - Alastair R Lyndon
- School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, John Muir Building, Riccarton, Edinburgh, UK
| | - Kohichi Tanaka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-Ku, Tokyo, Japan
| | - Jeffrey D Rothstein
- Department of Neurology and Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, MD, USA
| | - Paul A Skehel
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
| | - David J A Wyllie
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
- Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, India
| | - Mandy Jackson
- The Centre for Discovery Brain Sciences, The University of Edinburgh, Hugh Robson Building, Edinburgh, UK
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Robin G, López JR, Espinal GM, Hulsizer S, Hagerman PJ, Pessah IN. Calcium dysregulation and Cdk5-ATM pathway involved in a mouse model of fragile X-associated tremor/ataxia syndrome. Hum Mol Genet 2017; 26:2649-2666. [PMID: 28444183 PMCID: PMC5886271 DOI: 10.1093/hmg/ddx148] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 04/06/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurological disorder that affects premutation carriers with 55-200 CGG-expansion repeats (preCGG) in FMR1, presenting with early alterations in neuronal network formation and function that precede neurodegeneration. Whether intranuclear inclusions containing DNA damage response (DDR) proteins are causally linked to abnormal synaptic function, neuronal growth and survival are unknown. In a mouse that harbors a premutation CGG expansion (preCGG), cortical and hippocampal FMRP expression is moderately reduced from birth through adulthood, with greater FMRP reductions in the soma than in the neurite, despite several-fold elevation of Fmr1 mRNA levels. Resting cytoplasmic calcium concentration ([Ca2+]i) in cultured preCGG hippocampal neurons is chronically elevated, 3-fold compared to Wt; elevated ROS and abnormal glutamatergic responses are detected at 14 DIV. Elevated µ-calpain activity and a higher p25/p35 ratio in the cortex of preCGG young adult mice indicate abnormal Cdk5 regulation. In support, the Cdk5 substrate, ATM, is upregulated by 1.5- to 2-fold at P0 and 6 months in preCGG brain, as is p-Ser1981-ATM. Bax:Bcl-2 is 30% higher in preCGG brain, indicating a greater vulnerability to apoptotic activation. Elevated [Ca2+]i, ROS, and DDR signals are normalized with dantrolene. Chronic [Ca2+]i dysregulation amplifies Cdk5-ATM signaling, possibly linking impaired glutamatergic signaling and DDR to neurodegeneration in preCGG brain.
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Affiliation(s)
- Gaëlle Robin
- Department Molecular Biosciences, School of Veterinary Medicine, Davis, CA, USA
| | - José R. López
- Department Molecular Biosciences, School of Veterinary Medicine, Davis, CA, USA
| | - Glenda M. Espinal
- Department of Biochemistry and Molecular Medicine, UC Davis, Davis, CA 95616, USA
| | - Susan Hulsizer
- Department Molecular Biosciences, School of Veterinary Medicine, Davis, CA, USA
| | - Paul J. Hagerman
- Department of Biochemistry and Molecular Medicine, UC Davis, Davis, CA 95616, USA
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, Sacramento, CA 95817, USA
| | - Isaac N. Pessah
- Department Molecular Biosciences, School of Veterinary Medicine, Davis, CA, USA
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, Sacramento, CA 95817, USA
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14
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Notartomaso S, Mascio G, Scarselli P, Martinello K, Fucile S, Gradini R, Bruno V, Battaglia G, Nicoletti F. Expression of the K +/Cl - cotransporter, KCC2, in cerebellar Purkinje cells is regulated by group-I metabotropic glutamate receptors. Neuropharmacology 2017; 115:51-59. [PMID: 27498071 DOI: 10.1016/j.neuropharm.2016.07.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 06/30/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
The neuronal K+/Cl- symporter, KCC2, shapes synaptic responses mediated by Cl--permeant GABAA receptors. Moving from the evidence that excitatory neurotransmission drives changes in KCC2 expression in cerebellar neurons, we studied the regulation of KCC2 expression by group-I metabotropic glutamate (mGlu) receptors in the cerebellum of adult mice. Mice lacking mGlu5 receptors showed a large reduction in cerebellar KCC2 protein levels and a loss of KCC2 immunoreactivity in Purkinje cells. Similar changes were seen in mice treated with the mGlu5 receptor antagonist, MPEP, whereas treatment with the mGlu5 receptor positive allosteric modulator (PAM), VU0360172, increased KCC2 expression. In contrast, pharmacological inhibition of mGlu1 receptors with JNJ16259685 enhanced cerebellar KCC2 protein levels and KCC2 immunoreactivity in Purkinje cells, whereas treatment with the mGlu1 receptor PAM, RO0711401, reduced KCC2 expression. To examine whether the reduction in KCC2 expression caused by the absence or the inhibition of mGlu5 receptors could affect GABAergic transmission, we performed electrophysiological and behavioral studies. Recording of extracellular action potentials in Purkinje cells showed that the inhibitory effect of the GABAA receptor agonist, muscimol, was lost in cerebellar slices prepared from mGlu5-/- mice or from mice treated systemically with MPEP, in line with the reduction in KCC2 expression. Similarly, motor impairment caused by the GABAA receptor PAM, diazepam, was attenuated in mice pre-treated with MPEP. These findings disclose a novel function of mGlu5 receptors in the cerebellum and suggest that mGlu5 receptor ligands might influence GABAergic transmission in the cerebellum and affect motor responses to GABA-mimetic drugs. This article is part of the Special Issue entitled 'Metabotropic Glutamate Receptors, 5 years on'.
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Affiliation(s)
| | | | | | | | - Sergio Fucile
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy
| | - Roberto Gradini
- IRCCS Neuromed, Pozzilli, Italy; Department of Experimental Medicine, University Sapienza of Rome, Italy
| | - Valeria Bruno
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy
| | | | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy; Department of Physiology and Pharmacology, University Sapienza of Rome, Italy.
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15
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Sellier C, Buijsen RAM, He F, Natla S, Jung L, Tropel P, Gaucherot A, Jacobs H, Meziane H, Vincent A, Champy MF, Sorg T, Pavlovic G, Wattenhofer-Donze M, Birling MC, Oulad-Abdelghani M, Eberling P, Ruffenach F, Joint M, Anheim M, Martinez-Cerdeno V, Tassone F, Willemsen R, Hukema RK, Viville S, Martinat C, Todd PK, Charlet-Berguerand N. Translation of Expanded CGG Repeats into FMRpolyG Is Pathogenic and May Contribute to Fragile X Tremor Ataxia Syndrome. Neuron 2017; 93:331-347. [PMID: 28065649 PMCID: PMC5263258 DOI: 10.1016/j.neuron.2016.12.016] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/06/2016] [Accepted: 12/02/2016] [Indexed: 11/26/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a limited expansion of CGG repeats in the 5′ UTR of FMR1. Two mechanisms are proposed to cause FXTAS: RNA gain-of-function, where CGG RNA sequesters specific proteins, and translation of CGG repeats into a polyglycine-containing protein, FMRpolyG. Here we developed transgenic mice expressing CGG repeat RNA with or without FMRpolyG. Expression of FMRpolyG is pathogenic, while the sole expression of CGG RNA is not. FMRpolyG interacts with the nuclear lamina protein LAP2β and disorganizes the nuclear lamina architecture in neurons differentiated from FXTAS iPS cells. Finally, expression of LAP2β rescues neuronal death induced by FMRpolyG. Overall, these results suggest that translation of expanded CGG repeats into FMRpolyG alters nuclear lamina architecture and drives pathogenesis in FXTAS. CGG repeats in the 5′ UTR of FMR1 are translated through initiation to an ACG codon Translation of CGG repeats in the polyglycine protein, FMRpolyG, is toxic in mice FMRpolyG binds and disrupts protein of the nuclear lamina
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Affiliation(s)
- Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
| | - Ronald A M Buijsen
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Fang He
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran Association Health System, Ann Arbor, MI 48105, USA; Department of Biological and Health Sciences, Texas A&M University - Kingsville, Kingsville, TX 78363, USA
| | - Sam Natla
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Laura Jung
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Philippe Tropel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Angeline Gaucherot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Hugues Jacobs
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Hamid Meziane
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Alexandre Vincent
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie-France Champy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Tania Sorg
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Guillaume Pavlovic
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie Wattenhofer-Donze
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie-Christine Birling
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mustapha Oulad-Abdelghani
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Pascal Eberling
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Frank Ruffenach
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mathilde Joint
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mathieu Anheim
- Department of Neurology, University Hospital of Strasbourg, Hôpital de Hautepierre, 67200 Strasbourg, France
| | - Veronica Martinez-Cerdeno
- Department of Pathology and Laboratory Medicine, University of California, Davis, Sacramento, CA 95817, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; M.I.N.D. Institute, University of California, Davis, Health System, Sacramento, CA 95817, USA
| | - Flora Tassone
- M.I.N.D. Institute, University of California, Davis, Health System, Sacramento, CA 95817, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Stéphane Viville
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; Laboratoire de Diagnostic Génétique, UF3472 - Infertilité, Nouvel Hôpital Civil, 1 place de l'Hôpital, 67091 Strasbourg, France; IPPTS, 3 rue Koeberlé, 67000 Strasbourg, France
| | | | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran Association Health System, Ann Arbor, MI 48105, USA
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France.
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Cerebellar volume mediates the relationship between FMR1 mRNA levels and voluntary step initiation in males with the premutation. Neurobiol Aging 2016; 50:5-12. [PMID: 27837676 DOI: 10.1016/j.neurobiolaging.2016.10.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 08/31/2016] [Accepted: 10/08/2016] [Indexed: 01/14/2023]
Abstract
Recent evidence indicates that adults with a premutation (PM: 55-199 CGG repeats) expansion in the fragile X mental retardation 1 (FMR1) gene show postural control deficits that may reflect disruption to cerebellar motor regions. Less is known about the influence of reduced cerebellar volume and structural changes, and increase in CGG repeat and FMR1 mRNA levels on the attentional demands of step initiation in PM males. We investigated the effects of a concurrent cognitive task on choice stepping reaction time (CSRT) and explored the associations between CSRT performance, cerebellar volume, CGG size, and FMR1 mRNA levels in blood in PM males. We examined 19 PM males (ages 28-75) and 23 matched controls (CGG <44; ages 26-77), who performed a verbal fluency task during CSRT performance and single-task stepping without a secondary cognitive task. Our results provide preliminary evidence that smaller cerebellar volume (β = -2.73, p = 0.002) and increasing CGG repeat length (β = 1.69, p = 0.003) were associated with greater dual-task step initiation times in PM males, but not in controls. There was evidence of a mediating effect of cerebellar volume on the relationship between FMR1 mRNA levels and single-task CSRT performance in PM males (estimate coefficient = 8.69, standard error = 4.42, p = 0.049). These findings suggest increasing CGG repeat and FMR1 mRNA levels have neurotoxic effects on cerebellar regions underlying anticipatory postural responses during stepping. Cerebellar postural changes may be predictive of the increased risk of falls in older PM males.
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17
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Giulivi C, Napoli E, Tassone F, Halmai J, Hagerman R. Plasma Biomarkers for Monitoring Brain Pathophysiology in FMR1 Premutation Carriers. Front Mol Neurosci 2016; 9:71. [PMID: 27570505 PMCID: PMC4981605 DOI: 10.3389/fnmol.2016.00071] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 07/29/2016] [Indexed: 12/12/2022] Open
Abstract
Premutation carriers have a 55–200 CGG expansion in the fragile X mental retardation 1 (FMR1) gene. Currently, 1.5 million individuals are affected in the United States, and carriers are at risk of developing the late-onset neurodegenerative disorder Fragile X-associated tremor ataxia syndrome (FXTAS). Limited efforts have been made to develop new methods for improved early patient monitoring, treatment response, and disease progression. To this end, plasma metabolomic phenotyping was obtained for 23 premutation carriers and 16 age- and sex-matched controls. Three biomarkers, phenylethylamine normalized by either aconitate or isocitrate and oleamide normalized by isocitrate, exhibited excellent model performance. The lower phenylethylamine and oleamide plasma levels in carriers may indicate, respectively, incipient nigrostriatal degeneration and higher incidence of substance abuse, anxiety and sleep disturbances. Higher levels of citrate, isocitrate, aconitate, and lactate may reflect deficits in both bioenergetics and neurotransmitter metabolism (Glu, GABA). This study lays important groundwork by defining the potential utility of plasma metabolic profiling to monitor brain pathophysiology in carriers before and during the progression of FXTAS, treatment efficacy and evaluation of side effects.
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Affiliation(s)
- Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CAUSA; Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Davis, CAUSA
| | - Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA USA
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Davis, CAUSA; Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CAUSA
| | - Julian Halmai
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA USA
| | - Randi Hagerman
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Davis, CAUSA; Department of Pediatrics, University of California Davis Medical Center, Sacramento, CAUSA
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18
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Belagodu AP, Zendeli L, Slater BJ, Galvez R. Blocking elevated VEGF‐A attenuates non‐vasculature Fragile X syndrome abnormalities. Dev Neurobiol 2016; 77:14-25. [DOI: 10.1002/dneu.22404] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/15/2016] [Accepted: 05/31/2016] [Indexed: 01/19/2023]
Affiliation(s)
- Amogh P. Belagodu
- Neuroscience Program, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
| | - Liridon Zendeli
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
| | - Bernard J. Slater
- Neuroscience Program, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
| | - Roberto Galvez
- Neuroscience Program, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
- Psychology DepartmentUniversity of Illinois at Urbana‐Champaign405 N Mathews AveUrbana Illinois61801
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19
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Metabotropic glutamate receptor 5 – a promising target in drug development and neuroimaging. Eur J Nucl Med Mol Imaging 2016; 43:1151-70. [DOI: 10.1007/s00259-015-3301-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 12/22/2015] [Indexed: 10/22/2022]
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20
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Fatemi SH, Folsom TD. GABA receptor subunit distribution and FMRP-mGluR5 signaling abnormalities in the cerebellum of subjects with schizophrenia, mood disorders, and autism. Schizophr Res 2015; 167:42-56. [PMID: 25432637 PMCID: PMC5301472 DOI: 10.1016/j.schres.2014.10.010] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 10/06/2014] [Accepted: 10/08/2014] [Indexed: 12/24/2022]
Abstract
Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. GABAergic receptor abnormalities have been documented in several major psychiatric disorders including schizophrenia, mood disorders, and autism. Abnormal expression of mRNA and protein for multiple GABA receptors has also been observed in multiple brain regions leading to alterations in the balance between excitatory/inhibitory signaling in the brain with potential profound consequences for normal cognition and maintenance of mood and perception. Altered expression of GABAA receptor subunits has been documented in fragile X mental retardation 1 (FMR1) knockout mice, suggesting that loss of its protein product, fragile X mental retardation protein (FMRP), impacts GABAA subunit expression. Recent postmortem studies from our laboratory have shown reduced expression of FMRP in the brains of subjects with schizophrenia, bipolar disorder, major depression, and autism. FMRP acts as a translational repressor and, under normal conditions, inhibits metabotropic glutamate receptor 5 (mGluR5)-mediated signaling. In fragile X syndrome (FXS), the absence of FMRP is hypothesized to lead to unregulated mGluR5 signaling, ultimately resulting in the behavioral and intellectual impairments associated with this disorder. Our laboratory has identified changes in mGluR5 expression in autism, schizophrenia, and mood disorders. In the current review article, we discuss our postmortem data on GABA receptors, FMRP, and mGluR5 levels and compare our results with other laboratories. Finally, we discuss the interactions between these molecules and the potential for new therapeutic interventions that target these interconnected signaling systems.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, 420 Delaware St SE, MMC 392, Minneapolis, MN 55455, USA; Department of Neuroscience, University of Minnesota Medical School, 321 Church St. SE, Minneapolis, MN 55455, USA.
| | - Timothy D Folsom
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, 420 Delaware St SE, MMC 392, Minneapolis, MN 55455, USA.
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21
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Basuta K, Schneider A, Gane L, Polussa J, Woodruff B, Pretto D, Hagerman R, Tassone F. High functioning male with fragile X syndrome and fragile X-associated tremor/ataxia syndrome. Am J Med Genet A 2015; 167A:2154-61. [DOI: 10.1002/ajmg.a.37125] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/06/2015] [Indexed: 01/05/2023]
Affiliation(s)
- Kirin Basuta
- Department of Biochemistry and Molecular Medicine; School of Medicine, University of California; Sacramento California
| | - Andrea Schneider
- MIND Institute; University of California, Davis, Medical Center; Sacramento California
- Department of Pediatrics; University of California at Davis Medical Center; Sacramento California
| | - Louise Gane
- MIND Institute; University of California, Davis, Medical Center; Sacramento California
| | - Jonathan Polussa
- MIND Institute; University of California, Davis, Medical Center; Sacramento California
- Department of Pediatrics; University of California at Davis Medical Center; Sacramento California
| | - Bryan Woodruff
- Department of Neurology; Mayo Clinic; Scottsdale Arizona
| | - Dalyir Pretto
- Department of Biochemistry and Molecular Medicine; School of Medicine, University of California; Sacramento California
| | - Randi Hagerman
- MIND Institute; University of California, Davis, Medical Center; Sacramento California
- Department of Pediatrics; University of California at Davis Medical Center; Sacramento California
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine; School of Medicine, University of California; Sacramento California
- MIND Institute; University of California, Davis, Medical Center; Sacramento California
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22
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Birch RC, Hocking DR, Cornish KM, Menant JC, Georgiou-Karistianis N, Godler DE, Wen W, Hackett A, Rogers C, Trollor JN. Preliminary evidence of an effect of cerebellar volume on postural sway in FMR1 premutation males. GENES BRAIN AND BEHAVIOR 2015; 14:251-9. [PMID: 25689687 DOI: 10.1111/gbb.12204] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 11/29/2022]
Abstract
Recent evidence suggests that early changes in postural control may be discernible among females with premutation expansions (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene at risk of developing fragile X-associated tremor ataxia syndrome (FXTAS). Cerebellar dysfunction is well described in males and females with FXTAS, yet the interrelationships between cerebellar volume, CGG repeat length, FMR1 messenger RNA (mRNA) levels and changes in postural control remain unknown. This study examined postural sway during standing in a cohort of 22 males with the FMR1 premutation (ages 26-80) and 24 matched controls (ages 26-77). The influence of cerebellar volume, CGG repeat length and FMR1 mRNA levels on postural sway was explored using multiple linear regression. The results provide preliminary evidence that increasing CGG repeat length and decreasing cerebellar volume were associated with greater postural sway among premutation males. The relationship between CGG repeat length and postural sway was mediated by a negative association between CGG repeat size and cerebellar volume. While FMR1 mRNA levels were significantly elevated in the premutation group and correlated with CGG repeat length, FMR1 mRNA levels were not significantly associated with postural sway scores. These findings show for the first time that greater postural sway among males with the FMR1 premutation may reflect CGG repeat-mediated disruption in vulnerable cerebellar circuits implicated in postural control. However, longitudinal studies in larger samples are required to confirm whether the relationships between cerebellar volume, CGG repeat length and postural sway indicate greater risk for neurological decline.
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Affiliation(s)
- R C Birch
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney
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23
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Pretto DI, Eid JS, Yrigollen CM, Tang HT, Loomis EW, Raske C, Durbin-Johnson B, Hagerman PJ, Tassone F. Differential increases of specific FMR1 mRNA isoforms in premutation carriers. J Med Genet 2014; 52:42-52. [PMID: 25358671 DOI: 10.1136/jmedgenet-2014-102593] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Over 40% of male and ∼16% of female carriers of a premutation FMR1 allele (55-200 CGG repeats) will develop fragile X-associated tremor/ataxia syndrome, an adult onset neurodegenerative disorder, while about 20% of female carriers will develop fragile X-associated primary ovarian insufficiency. Marked elevation in FMR1 mRNA transcript levels has been observed with premutation alleles, and RNA toxicity due to increased mRNA levels is the leading molecular mechanism proposed for these disorders. However, although the FMR1 gene undergoes alternative splicing, it is unknown whether all or only some of the isoforms are overexpressed in premutation carriers and which isoforms may contribute to the premutation pathology. METHODS To address this question, we have applied a long-read sequencing approach using single-molecule real-time (SMRT) sequencing and qRT-PCR. RESULTS Our SMRT sequencing analysis performed on peripheral blood mononuclear cells, fibroblasts and brain tissue samples derived from premutation carriers and controls revealed the existence of 16 isoforms of 24 predicted variants. Although the relative abundance of all mRNA isoforms was significantly increased in the premutation group, as expected based on the bulk increase in mRNA levels, there was a disproportionate (fourfold to sixfold) increase, relative to the overall increase in mRNA, in the abundance of isoforms spliced at both exons 12 and 14, specifically Iso10 and Iso10b, containing the complete exon 15 and differing only in splicing in exon 17. CONCLUSIONS These findings suggest that RNA toxicity may arise from a relative increase of all FMR1 mRNA isoforms. Interestingly, the Iso10 and Iso10b mRNA isoforms, lacking the C-terminal functional sites for fragile X mental retardation protein function, are the most increased in premutation carriers relative to normal, suggesting a functional relevance in the pathology of FMR1-associated disorders.
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Affiliation(s)
- Dalyir I Pretto
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - John S Eid
- Pacific Biosciences, Menlo Park, California, USA
| | - Carolyn M Yrigollen
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Hiu-Tung Tang
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Erick W Loomis
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Chris Raske
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Blythe Durbin-Johnson
- Department of Public Health Sciences, University of California Davis, School of Medicine, Davis, California, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA MIND Institute, University of California Davis Medical Center, Sacramento, California, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA MIND Institute, University of California Davis Medical Center, Sacramento, California, USA
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24
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Renoux AJ, Carducci NM, Ahmady AA, Todd PK. Fragile X mental retardation protein expression in Alzheimer's disease. Front Genet 2014; 5:360. [PMID: 25452762 PMCID: PMC4233940 DOI: 10.3389/fgene.2014.00360] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/27/2014] [Indexed: 12/31/2022] Open
Abstract
The FMR1 protein product, FMRP, is an mRNA binding protein associated with translational inhibition of target transcripts. One FMRP target is the amyloid precursor protein (APP) mRNA, and APP levels are elevated in Fmr1 KO mice. Given that elevated APP protein expression can elicit Alzheimer's disease (AD) in patients and model systems, we evaluated whether FMRP expression might be altered in Alzheimer's autopsy brain samples and mouse models compared to controls. In a double transgenic mouse model of AD (APP/PS1), we found no difference in FMRP expression in aged AD model mice compared to littermate controls. FMRP expression was also similar in AD and control patient frontal cortex and cerebellum samples. Fragile X-associated tremor/ataxia syndrome (FXTAS) is an age-related neurodegenerative disorder caused by expanded CGG repeats in the 5' untranslated region of the FMR1 gene. Patients experience cognitive impairment and dementia in addition to motor symptoms. In parallel studies, we measured FMRP expression in cortex and cerebellum from three FXTAS patients and found reduced expression compared to both controls and Alzheimer's patient brains, consistent with animal models. We also find increased APP levels in cerebellar, but not cortical, samples of FXTAS patients compared to controls. Taken together, these data suggest that a decrease in FMRP expression is unlikely to be a primary contributor to Alzheimer's disease pathogenesis.
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Affiliation(s)
- Abigail J Renoux
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, MI, USA ; Department of Neurology, University of Michigan , Ann Arbor, MI, USA
| | | | - Arya A Ahmady
- Department of Neurology, University of Michigan , Ann Arbor, MI, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan , Ann Arbor, MI, USA
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25
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Berman RF, Buijsen RA, Usdin K, Pintado E, Kooy F, Pretto D, Pessah IN, Nelson DL, Zalewski Z, Charlet-Bergeurand N, Willemsen R, Hukema RK. Mouse models of the fragile X premutation and fragile X-associated tremor/ataxia syndrome. J Neurodev Disord 2014; 6:25. [PMID: 25136376 PMCID: PMC4135345 DOI: 10.1186/1866-1955-6-25] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022] Open
Abstract
Carriers of the fragile X premutation (FPM) have CGG trinucleotide repeat expansions of between 55 and 200 in the 5'-UTR of FMR1, compared to a CGG repeat length of between 5 and 54 for the general population. Carriers were once thought to be without symptoms, but it is now recognized that they can develop a variety of early neurological symptoms as well as being at risk for developing the late onset neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS). Several mouse models have contributed to our understanding of FPM and FXTAS, and findings from studies using these models are summarized here. This review also discusses how this information is improving our understanding of the molecular and cellular abnormalities that contribute to neurobehavioral features seen in some FPM carriers and in patients with FXTAS. Mouse models show much of the pathology seen in FPM carriers and in individuals with FXTAS, including the presence of elevated levels of Fmr1 mRNA, decreased levels of fragile X mental retardation protein, and ubiquitin-positive intranuclear inclusions. Abnormalities in dendritic spine morphology in several brain regions are associated with neurocognitive deficits in spatial and temporal memory processes, impaired motor performance, and altered anxiety. In vitro studies have identified altered dendritic and synaptic architecture associated with abnormal Ca(2+) dynamics and electrical network activity. FPM mice have been particularly useful in understanding the roles of Fmr1 mRNA, fragile X mental retardation protein, and translation of a potentially toxic polyglycine peptide in pathology. Finally, the potential for using these and emerging mouse models for preclinical development of therapies to improve neurological function in FXTAS is considered.
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Affiliation(s)
- Robert F Berman
- Department of Neurological Surgery, Room 502C, UC Davis, 1515 Newton Court, Davis, CA 95618, USA
| | | | - Karen Usdin
- NIDDK, National Institutes of Health, Bethesda, MD, USA
| | | | - Frank Kooy
- Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
| | | | - Isaac N Pessah
- Department Molecular Biosciences, UC Davis, Davis, CA, USA
| | - David L Nelson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Zachary Zalewski
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | | | - Rob Willemsen
- Department Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Renate K Hukema
- Department Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
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26
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Impaired sensorimotor gating in Fmr1 knock out and Fragile X premutation model mice. Behav Brain Res 2014; 267:42-5. [PMID: 24657592 DOI: 10.1016/j.bbr.2014.03.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 03/04/2014] [Accepted: 03/11/2014] [Indexed: 01/20/2023]
Abstract
Fragile X syndrome (FXS) is a common inherited cause of intellectual disability that results from a CGG repeat expansion in the FMR1 gene. Large repeat expansions trigger both transcriptional and translational suppression of Fragile X protein (FMRP) production. Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) is an allelic neurodegenerative disease caused by smaller "pre-mutation" CGG repeat expansions that enhance FMR1 transcription but lead to translational inefficiency and reduced FMRP expression in animal models. Sensorimotor gating as measured by pre-pulse inhibition (PPI) is altered in both FXS patients and Fmr1 knock out (KO) mice. Similarly, FXTAS patients have demonstrated PPI deficits. Recent work suggests there may be overlapping synaptic defects between Fmr1 KO and CGG knock-in premutation mouse models (CGG KI). We therefore sought to interrogate PPI in CGG KI mice. Using a quiet PPI protocol more akin to human testing conditions, we find that Fmr1 KO animals have significantly impaired PPI. Using this same protocol, we find CGG KI mice demonstrate an age-dependent impairment in PPI compared to wild type (WT) controls. This study describes a novel phenotype in CGG KI mice that can be used in future therapeutic development targeting premutation associated symptoms.
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