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Schiavo A, Martins LA, Wearick-Silva LE, Orso R, Xavier LL, Mestriner RG. Can anxiety-like behavior and spatial memory predict the extremes of skilled walking performance in mice? An exploratory, preliminary study. Front Behav Neurosci 2023; 17:1059029. [PMID: 36926582 PMCID: PMC10011164 DOI: 10.3389/fnbeh.2023.1059029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/26/2023] [Indexed: 03/08/2023] Open
Abstract
Introduction Skilled walking is influenced by memory, stress, and anxiety. While this is evident in cases of neurological disorders, memory, and anxiety traits may predict skilled walking performance even in normal functioning. Here, we address whether spatial memory and anxiety-like behavior can predict skilled walking performance in mice. Methods A cohort of 60 adult mice underwent a behavioral assessment including general exploration (open field), anxiety-like behavior (elevated plus maze), working and spatial memory (Y-maze and Barnes maze), and skilled walking performance (ladder walking test). Three groups were established based on their skilled walking performance: superior (SP, percentiles ≥75), regular (RP, percentiles 74-26), and inferior (IP, percentiles ≤25) performers. Results Animals from the SP and IP groups spent more time in the elevated plus maze closed arms compared to the RP group. With every second spent in the elevated plus maze closed arms, the probability of the animal exhibiting extreme percentiles in the ladder walking test increased by 1.4%. Moreover, animals that spent 219 s (73% of the total time of the test) or more in those arms were 4.67 times more likely to exhibit either higher or lower percentiles of skilled walking performance. Discussion We discuss and conclude anxiety traits may influence skilled walking performance in facility-reared mice.
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Affiliation(s)
- Aniuska Schiavo
- Graduate Program in Biomedical Gerontology, School of Medicine, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,Neuroplasticity and Rehabilitation Research Group (NEUROPLAR), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Lucas Athaydes Martins
- Graduate Program in Biomedical Gerontology, School of Medicine, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,Neuroplasticity and Rehabilitation Research Group (NEUROPLAR), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Luís Eduardo Wearick-Silva
- Developmental Cognitive Neuroscience Lab (DCNL), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Rodrigo Orso
- Developmental Cognitive Neuroscience Lab (DCNL), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Léder Leal Xavier
- Neuroplasticity and Rehabilitation Research Group (NEUROPLAR), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,School of Health and Life Sciences, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
| | - Régis Gemerasca Mestriner
- Graduate Program in Biomedical Gerontology, School of Medicine, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,Neuroplasticity and Rehabilitation Research Group (NEUROPLAR), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.,School of Health and Life Sciences, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil
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2
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Schwartzer JJ, Garcia-Arocena D, Jamal A, Izadi A, Willemsen R, Berman RF. Allopregnanolone Improves Locomotor Activity and Arousal in the Aged CGG Knock-in Mouse Model of Fragile X-Associated Tremor/Ataxia Syndrome. Front Neurosci 2021; 15:752973. [PMID: 34924931 PMCID: PMC8678485 DOI: 10.3389/fnins.2021.752973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/11/2021] [Indexed: 01/21/2023] Open
Abstract
Carriers of the fragile X premutation (PM) can develop a variety of early neurological symptoms, including depression, anxiety and cognitive impairment as well as being at risk for developing the late-onset fragile X-associated tremor/ataxia syndrome (FXTAS). The absence of effective treatments for FXTAS underscores the importance of developing efficacious therapies to reduce the neurological symptoms in elderly PM carriers and FXTAS patients. A recent preliminary study reported that weekly infusions of Allopregnanolone (Allop) may improve deficits in executive function, learning and memory in FXTAS patients. Based on this study we examined whether Allop would improve neurological function in the aged CGG knock-in (CGG KI) dutch mouse, B6.129P2(Cg)-Fmr1tm2Cgr/Cgr, that models much of the symptomatology in PM carriers and FXTAS patients. Wild type and CGG KI mice received 10 weekly injections of Allop (10 mg/kg, s.c.), followed by a battery of behavioral tests of motor function, anxiety, and repetitive behavior, and 5-bromo-2'-deoxyuridine (BrdU) labeling to examine adult neurogenesis. The results provided evidence that Allop in CGG KI mice normalized motor performance and reduced thigmotaxis in the open field, normalized repetitive digging behavior in the marble burying test, but did not appear to increase adult neurogenesis in the hippocampus. Considered together, these results support further examination of Allop as a therapeutic strategy in patients with FXTAS.
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Affiliation(s)
- Jared J Schwartzer
- Program in Neuroscience and Behavior, Department of Psychology and Education, Mount Holyoke College, South Hadley, MA, United States
| | | | - Amanda Jamal
- Department of Neurological Surgery, University of California, Davis, Davis, CA, United States
| | - Ali Izadi
- Department of Neurological Surgery, University of California, Davis, Davis, CA, United States
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, Netherlands
| | - Robert F Berman
- Department of Neurological Surgery, University of California, Davis, Davis, CA, United States.,M.I.N.D. Institute, University of California, Davis, Davis, CA, United States
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3
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Wenzel HJ, Murray KD, Haify SN, Hunsaker MR, Schwartzer JJ, Kim K, La Spada AR, Sopher BL, Hagerman PJ, Raske C, Severijnen LAWFM, Willemsen R, Hukema RK, Berman RF. Astroglial-targeted expression of the fragile X CGG repeat premutation in mice yields RAN translation, motor deficits and possible evidence for cell-to-cell propagation of FXTAS pathology. Acta Neuropathol Commun 2019; 7:27. [PMID: 30808398 PMCID: PMC6390634 DOI: 10.1186/s40478-019-0677-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 02/10/2019] [Indexed: 01/01/2023] Open
Abstract
The fragile X premutation is a CGG trinucleotide repeat expansion between 55 and 200 repeats in the 5'-untranslated region of the fragile X mental retardation 1 (FMR1) gene. Human carriers of the premutation allele are at risk of developing the late-onset neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). Characteristic neuropathology associated with FXTAS includes intranuclear inclusions in neurons and astroglia. Previous studies recapitulated these histopathological features in neurons in a knock-in mouse model, but without significant astroglial pathology. To determine the role of astroglia in FXTAS, we generated a transgenic mouse line (Gfa2-CGG99-eGFP) that selectively expresses a 99-CGG repeat expansion linked to an enhanced green fluorescent protein (eGFP) reporter in astroglia throughout the brain, including cerebellar Bergmann glia. Behaviorally these mice displayed impaired motor performance on the ladder-rung test, but paradoxically better performance on the rotarod. Immunocytochemical analysis revealed that CGG99-eGFP co-localized with GFAP and S-100ß, but not with NeuN, Iba1, or MBP, indicating that CGG99-eGFP expression is specific to astroglia. Ubiquitin-positive intranuclear inclusions were found in eGFP-expressing glia throughout the brain. In addition, intracytoplasmic ubiquitin-positive inclusions were found outside the nucleus in distal astrocyte processes. Intriguingly, intranuclear inclusions, in the absence of eGFP mRNA and eGFP fluorescence, were present in neurons of the hypothalamus and neocortex. Furthermore, intranuclear inclusions in both neurons and astrocytes displayed immunofluorescent labeling for the polyglycine peptide FMRpolyG, implicating FMRpolyG in the pathology found in Gfa2-CGG99 mice. Considered together, these results show that Gfa2-CGG99 expression in mice is sufficient to induce key features of FXTAS pathology, including formation of intranuclear inclusions, translation of FMRpolyG, and deficits in motor function.
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Affiliation(s)
- H Jürgen Wenzel
- Department of Neurological Surgery, University of California, Davis, Davis, CA, USA
| | - Karl D Murray
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, Davis, CA, USA
| | - Saif N Haify
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Michael R Hunsaker
- Graduate Program in Neuroscience, University of California, Davis, Davis, CA, USA
| | - Jared J Schwartzer
- Program in Neuroscience and Behavior, Department of Psychology and Education, Mount Holyoke College, South Hadley, MA, USA
| | - Kyoungmi Kim
- Division of Biostatistics, Department of Public Health Sciences, University California Davis, Davis, CA, USA
| | - Albert R La Spada
- Departments of Neurology, Neurobiology, and Cell Biology, and the Duke Center for Neurodegeneration & Neurotherapeutics, Duke University School of Medicine, Durham, NC, USA
| | - Bryce L Sopher
- Department of Neurology, University of Washington School of Medicine, Seattle, WA, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA
| | - Christopher Raske
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, CA, USA
| | | | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Robert F Berman
- Department of Neurological Surgery, University of California, Davis, Davis, CA, USA.
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Dahlhaus R. Of Men and Mice: Modeling the Fragile X Syndrome. Front Mol Neurosci 2018; 11:41. [PMID: 29599705 PMCID: PMC5862809 DOI: 10.3389/fnmol.2018.00041] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/31/2018] [Indexed: 12/26/2022] Open
Abstract
The Fragile X Syndrome (FXS) is one of the most common forms of inherited intellectual disability in all human societies. Caused by the transcriptional silencing of a single gene, the fragile x mental retardation gene FMR1, FXS is characterized by a variety of symptoms, which range from mental disabilities to autism and epilepsy. More than 20 years ago, a first animal model was described, the Fmr1 knock-out mouse. Several other models have been developed since then, including conditional knock-out mice, knock-out rats, a zebrafish and a drosophila model. Using these model systems, various targets for potential pharmaceutical treatments have been identified and many treatments have been shown to be efficient in preclinical studies. However, all attempts to turn these findings into a therapy for patients have failed thus far. In this review, I will discuss underlying difficulties and address potential alternatives for our future research.
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Affiliation(s)
- Regina Dahlhaus
- Institute for Biochemistry, Emil-Fischer Centre, University of Erlangen-Nürnberg, Erlangen, Germany
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5
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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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Hunsaker MR, Smith GK, Kesner RP. Adaptation of the Arizona Cognitive Task Battery for use with the Ts65Dn mouse model (Mus musculus) of Down syndrome. ACTA ACUST UNITED AC 2017; 131:189-206. [PMID: 28333487 DOI: 10.1037/com0000069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We propose and validate a clear strategy to efficiently and comprehensively characterize neurobehavioral deficits in the Ts65Dn mouse model of Down syndrome. This novel approach uses neurocognitive theory to design and select behavioral tasks that test specific hypotheses concerning the results of Down syndrome. In this article, we model the Arizona Cognitive Task Battery, used to study human populations with Down syndrome, in Ts65Dn mice. We observed specific deficits for spatial memory, impaired long-term memory for visual objects, acquisition and reversal of motor responses, reduced motor dexterity, and impaired adaptive function as measured by nesting and anxiety tasks. The Ts65Dn mice showed intact temporal ordering, novelty detection, and visual object recognition with short delays. These results phenocopy the performance of participants with Down syndrome on the Arizona Cognitive Task Battery. This approach extends the utility of mouse models of Down syndrome by integrating the expertise of clinical neurology and cognitive neuroscience into the mouse behavioral laboratory. Further, by directly emphasizing the reciprocal translation of research between human disease states and the associated mouse models, we demonstrate that it is possible for both groups to mutually inform each other's research to more efficiently generate hypotheses and elucidate treatment strategies. (PsycINFO Database Record
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7
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Foote M, Arque G, Berman RF, Santos M. Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS) Motor Dysfunction Modeled in Mice. CEREBELLUM (LONDON, ENGLAND) 2016; 15:611-22. [PMID: 27255703 PMCID: PMC5014696 DOI: 10.1007/s12311-016-0797-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects some carriers of the fragile X premutation (PM). In PM carriers, there is a moderate expansion of a CGG trinucleotide sequence (55-200 repeats) in the fragile X gene (FMR1) leading to increased FMR1 mRNA and small to moderate decreases in the fragile X mental retardation protein (FMRP) expression. The key symptoms of FXTAS include cerebellar gait ataxia, kinetic tremor, sensorimotor deficits, neuropsychiatric changes, and dementia. While the specific trigger(s) that causes PM carriers to progress to FXTAS pathogenesis remains elusive, the use of animal models has shed light on the underlying neurobiology of the altered pathways involved in disease development. In this review, we examine the current use of mouse models to study PM and FXTAS, focusing on recent advances in the field. Specifically, we will discuss the construct, face, and predictive validities of these PM mouse models, the insights into the underlying disease mechanisms, and potential treatments.
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Affiliation(s)
- Molly Foote
- Department of Neurological Surgery, University of California, Davis, CA, USA.
| | - Gloria Arque
- Department of Molecular Neuroscience, Medical University of Vienna, Vienna, Austria
| | - Robert F Berman
- Department of Neurological Surgery, University of California, Davis, CA, USA
| | - Mónica Santos
- Institute of Biology, Otto-von-Guericke University, Magdeburg, Germany
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Aavani T, Rana SA, Hawkes R, Pittman QJ. Maternal immune activation produces cerebellar hyperplasia and alterations in motor and social behaviors in male and female mice. THE CEREBELLUM 2016; 14:491-505. [PMID: 25863812 DOI: 10.1007/s12311-015-0669-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
There have been suggestions that maternal immune activation is associated with alterations in motor behavior in offspring. To explore this further, we treated pregnant mice with polyinosinic:polycytidylic acid (poly(I:C)), a viral mimetic that activates the innate immune system, or saline on embryonic days 13-15. At postnatal day (P) 18, offspring cerebella were collected from perfused brains and immunostained as whole-mounts for zebrin II. Measurements of zebrin II+/- stripes in both sexes indicated that prenatal poly(I:C)-exposed offspring had significantly wider stripes; this difference was also seen in similarly treated offspring in adulthood (~P120). When sagittal sections of the cerebellum were immunostained for calbindin and Purkinje cell numbers were counted, we observed greater numbers of Purkinje cells in poly(I:C) offspring at both P18 and ~ P120. In adolescence (~P40), both male and female prenatal poly(I:C)-exposed offspring exhibited poorer performance on the rotarod and ladder rung tests; deficits in performance on the latter test persisted into adulthood. Offspring of both sexes from poly(I:C) dams also exhibited impaired social interaction in adolescence, but this difference was no longer apparent in adulthood. Our results suggest that maternal immune exposure at a critical time of cerebellum development can enhance neuronal survival or impair normal programmed cell death of Purkinje cells, with lasting consequences on cerebellar morphology and a variety of motor and non-motor behaviors.
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Affiliation(s)
- Tooka Aavani
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, T2N 4N1, Alberta, Canada
| | - Shadna A Rana
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, T2N 4N1, Alberta, Canada
| | - Richard Hawkes
- Department of Cell Biology & Anatomy, Genes & Development Research Group, Hotchkiss Brain Institute, Cumming School of Medicine, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, T2N 4N1, Canada
| | - Quentin J Pittman
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Cumming School of Medicine, Health Sciences Centre, University of Calgary, 3330 Hospital Drive NW, Calgary, T2N 4N1, Alberta, Canada.
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Foote MM, Careaga M, Berman RF. What has been learned from mouse models of the Fragile X Premutation and Fragile X-associated tremor/ataxia syndrome? Clin Neuropsychol 2016; 30:960-72. [PMID: 27355912 DOI: 10.1080/13854046.2016.1158254] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To describe in this review how research using mouse models developed to study the Fragile X premutation (PM) and Fragile X-associated tremor/ataxia syndrome (FXTAS) have contributed to understanding these disorders. PM carriers bear an expanded CGG trinucleotide repeat on the Fragile X Mental Retardation 1 (FMR1) gene, and are at risk for developing the late onset neurodegenerative disorder FXTAS. CONCLUSIONS Much has been learned about these genetic disorders from the development and study of mouse models. This includes new insights into the early cellular and molecular events that occur in PM carriers and in FXTAS, the presence of multiorgan pathology beyond the CNS, immunological dysregulation, unexpected synthesis of a potentially toxic peptide in FXTAS (i.e., FMRpolyG), and evidence that the disease process may be halted or reversed by appropriate molecular therapies given early in the course of disease.
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Affiliation(s)
- Molly M Foote
- a Department of Neurological Surgery , University of California Davis , Davis , CA , USA
| | - Milo Careaga
- b Department of Psychiatry and UC Davis M.I.N.D. Institute , University of California Davis , Davis , CA , USA
| | - Robert F Berman
- c Department of Neurological Surgery and the UC Davis M.I.N.D. Institute , University of California Davis , Davis , CA , USA
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Napoli E, Ross-Inta C, Song G, Wong S, Hagerman R, Gane LW, Smilowitz JT, Tassone F, Giulivi C. Premutation in the Fragile X Mental Retardation 1 (FMR1) Gene Affects Maternal Zn-milk and Perinatal Brain Bioenergetics and Scaffolding. Front Neurosci 2016; 10:159. [PMID: 27147951 PMCID: PMC4835505 DOI: 10.3389/fnins.2016.00159] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/29/2016] [Indexed: 12/12/2022] Open
Abstract
Fragile X premutation alleles have 55–200 CGG repeats in the 5′ UTR of the FMR1 gene. Altered zinc (Zn) homeostasis has been reported in fibroblasts from >60 years old premutation carriers, in which Zn supplementation significantly restored Zn-dependent mitochondrial protein import/processing and function. Given that mitochondria play a critical role in synaptic transmission, brain function, and cognition, we tested FMRP protein expression, brain bioenergetics, and expression of the Zn-dependent synaptic scaffolding protein SH3 and multiple ankyrin repeat domains 3 (Shank3) in a knock-in (KI) premutation mouse model with 180 CGG repeats. Mitochondrial outcomes correlated with FMRP protein expression (but not FMR1 gene expression) in KI mice and human fibroblasts from carriers of the pre- and full-mutation. Significant deficits in brain bioenergetics, Zn levels, and Shank3 protein expression were observed in the Zn-rich regions KI hippocampus and cerebellum at PND21, with some of these effects lasting into adulthood (PND210). A strong genotype × age interaction was observed for most of the outcomes tested in hippocampus and cerebellum, whereas in cortex, age played a major role. Given that the most significant effects were observed at the end of the lactation period, we hypothesized that KI milk might have a role at compounding the deleterious effects on the FMR1 genetic background. A higher gene expression of ZnT4 and ZnT6, Zn transporters abundant in brain and lactating mammary glands, was observed in the latter tissue of KI dams. A cross-fostering experiment allowed improving cortex bioenergetics in KI pups nursing on WT milk. Conversely, WT pups nursing on KI milk showed deficits in hippocampus and cerebellum bioenergetics. A highly significant milk type × genotype interaction was observed for all three-brain regions, being cortex the most influenced. Finally, lower milk-Zn levels were recorded in milk from lactating women carrying the premutation as well as other Zn-related outcomes (Zn-dependent alkaline phosphatase activity and lactose biosynthesis—whose limiting step is the Zn-dependent β-1,4-galactosyltransferase). In premutation carriers, altered Zn homeostasis, brain bioenergetics and Shank3 levels could be compounded by Zn-deficient milk, increasing the risk of developing emotional and neurological/cognitive problems and/or FXTAS later in life.
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Affiliation(s)
- Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Catherine Ross-Inta
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Gyu Song
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Sarah Wong
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Randi Hagerman
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA; Department of Pediatrics, University of California Davis Medical CenterSacramento, CA, USA
| | - Louise W Gane
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, Davis Davis, CA, USA
| | - Jennifer T Smilowitz
- Department of Food Science and Technology and Foods for Health Institute, University of California, Davis Davis, CA, USA
| | - Flora Tassone
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA; Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, DavisDavis, CA, USA
| | - Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary MedicineDavis, CA, USA; Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA
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Hukema RK, Buijsen RAM, Raske C, Severijnen LA, Nieuwenhuizen-Bakker I, Minneboo M, Maas A, de Crom R, Kros JM, Hagerman PJ, Berman RF, Willemsen R. Induced expression of expanded CGG RNA causes mitochondrial dysfunction in vivo. Cell Cycle 2015; 13:2600-8. [PMID: 25486200 DOI: 10.4161/15384101.2014.943112] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder affecting carriers of premutation forms of the FMR1 gene, resulting in a progressive development of tremor, ataxia and neuropsychological problems. The disease is caused by an expanded CGG repeat in the FMR1 gene, leading to an RNA gain-of-function toxicity mechanism. In order to study the pathogenesis of FXTAS, new inducible transgenic mouse models have been developed that expresses either 11CGGs or 90CGGs at the RNA level under control of a Tet-On promoter. When bred to an hnRNP-rtTA driver line, doxycycline (dox) induced expression of the transgene could be found in almost all tissues. Dox exposure resulted in loss of weight and death within 5 d for the 90CGG RNA expressing mice. Immunohistochemical examination of tissues of these mice revealed steatosis and apoptosis in the liver. Decreased expression of GPX1 and increased expression of cytochrome C is found. These effects were not seen in mice expressing a normal sized 11CGG repeat. In conclusion, we were able to show in vivo that expression of an expanded CGG-repeat rather than overexpression of a normal CGG-repeat causes pathology. In addition, we have shown that expanded CGG RNA expression can cause mitochondrial dysfunction by regulating expression levels of several markers. Although FTXAS patients do not display liver abnormalities, our findings contribute to understanding of the molecular mechanisms underlying toxicity of CGG repeat RNA expression in an animal model. In addition, the dox inducible mouse lines offer new opportunities to study therapeutic interventions for FXTAS.
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Affiliation(s)
- Renate K Hukema
- a Department of Clinical Genetics ; Erasmus MC ; Rotterdam , The Netherlands
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12
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Hocking DR, Kraan CM, Godler DE, Bui QM, Li X, Bradshaw JL, Georgiou-Karistianis N, Metcalfe SA, Archibald AD, Turbitt E, Fielding J, Trollor J, Cohen J, Cornish KM. Evidence linking FMR1 mRNA and attentional demands of stepping and postural control in women with the premutation. Neurobiol Aging 2014; 36:1400-8. [PMID: 25541421 DOI: 10.1016/j.neurobiolaging.2014.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 09/25/2014] [Accepted: 11/21/2014] [Indexed: 10/24/2022]
Abstract
Recent studies in young adult females with the fragile X mental retardation 1 (FMR1) gene premutation (PM) have shown subtle but significant impairments in executive control and postural stability. Less is known about the influence of age and FMR1 gene expression on executive control and postural stability in females with the PM. Here, we examined the attentional demands of reactive stepping using a well-validated measure of choice stepping reaction time under dual-task interference. We explored the interrelationships between step initiation times during a concurrent verbal fluency task and specific impairments in executive control previously reported in females with the PM. Our results showed increased dual-task interference on step initiation times and variability in female PM compared with control subjects. In addition, we observed greater choice stepping reaction time dual-task costs above the breakpoint of 81 CGG repeats relative to below this CGG range. Dual-task interference on both reaction time and movement time were significantly predicted by low working memory capacity in female PM carriers. Importantly, we revealed that FMR1 messenger RNA level is the most significant predictor accounting for dual-task stepping variability in both reaction time and movement time in PM females. These findings for the first time provide evidence linking elevated FMR1 messenger RNA levels that have been previously associated with FMR1 RNA toxicity and deficits in cerebellar motor and cognitive networks in a subgroup of at-risk PM women.
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Affiliation(s)
- Darren R Hocking
- Olga Tennison Autism Research Centre, School of Psychological Science, La Trobe University, Bundoora, Victoria, Australia.
| | - Claudine M Kraan
- School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - David E Godler
- Cyto-molecular Diagnostics Research, Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Quang M Bui
- Centre for Epidemiology and Biostatistics, School of Population and Global Health, University of Melbourne, Carlton, Victoria, Australia
| | - Xin Li
- Cyto-molecular Diagnostics Research, Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - John L Bradshaw
- School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Nellie Georgiou-Karistianis
- School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Sylvia A Metcalfe
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Alison D Archibald
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria, Australia; Victorian Clinical Genetics Services, Parkville, Victoria, Australia
| | - Erin Turbitt
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Joanne Fielding
- School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia
| | - Julian Trollor
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, Australia; Centre for Healthy Brain Ageing, School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Jonathan Cohen
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia; Centre for Developmental Disability Health Victoria, Monash University, Clayton, Victoria, Australia; Fragile X Alliance Inc (Clinic and Resource Centre), North Caulfield, Victoria, Australia
| | - Kim M Cornish
- School of Psychological Sciences, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria, Australia.
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Qin M, Huang T, Liu Z, Kader M, Burlin T, Xia Z, Zeidler Z, Hukema RK, Smith CB. Cerebral protein synthesis in a knockin mouse model of the fragile X premutation. ASN Neuro 2014; 6:6/5/1759091414551957. [PMID: 25290064 PMCID: PMC4187003 DOI: 10.1177/1759091414551957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The (CGG)n-repeat in the 5′-untranslated region of the fragile X mental retardation gene (FMR1) gene is polymorphic and may become unstable on transmission to the next generation. In fragile X syndrome, CGG repeat lengths exceed 200, resulting in silencing of FMR1 and absence of its protein product, fragile X mental retardation protein (FMRP). CGG repeat lengths between 55 and 200 occur in fragile X premutation (FXPM) carriers and have a high risk of expansion to a full mutation on maternal transmission. FXPM carriers have an increased risk for developing progressive neurodegenerative syndromes and neuropsychological symptoms. FMR1 mRNA levels are elevated in FXPM, and it is thought that clinical symptoms might be caused by a toxic gain of function due to elevated FMR1 mRNA. Paradoxically, FMRP levels decrease moderately with increasing CGG repeat length in FXPM. Lowered FMRP levels may also contribute to the appearance of clinical problems. We previously reported increases in regional rates of cerebral protein synthesis (rCPS) in the absence of FMRP in an Fmr1 knockout mouse model and in a FXPM knockin (KI) mouse model with 120 to 140 CGG repeats in which FMRP levels are profoundly reduced (80%–90%). To explore whether the concentration of FMRP contributes to the rCPS changes, we measured rCPS in another FXPM KI model with a similar CGG repeat length and a 50% reduction in FMRP. In all 24 brain regions examined, rCPS were unaffected. These results suggest that even with 50% reductions in FMRP, normal protein synthesis rates are maintained.
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Affiliation(s)
- Mei Qin
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Tianjian Huang
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Zhonghua Liu
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Michael Kader
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Burlin
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Zengyan Xia
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Zachary Zeidler
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | - Carolyn B Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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14
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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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15
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Ludwig AL, Espinal GM, Pretto DI, Jamal AL, Arque G, Tassone F, Berman RF, Hagerman PJ. CNS expression of murine fragile X protein (FMRP) as a function of CGG-repeat size. Hum Mol Genet 2014; 23:3228-38. [PMID: 24463622 DOI: 10.1093/hmg/ddu032] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Large expansions of a CGG-repeat element (>200 repeats; full mutation) in the fragile X mental retardation 1 (FMR1) gene cause fragile X syndrome (FXS), the leading single-gene form of intellectual disability and of autism spectrum disorder. Smaller expansions (55-200 CGG repeats; premutation) result in the neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). Whereas FXS is caused by gene silencing and insufficient FMR1 protein (FMRP), FXTAS is thought to be caused by 'toxicity' of expanded-CGG-repeat mRNA. However, as FMRP expression levels decrease with increasing CGG-repeat length, lowered protein may contribute to premutation-associated clinical involvement. To address this issue, we measured brain Fmr1 mRNA and FMRP levels as a function of CGG-repeat length in a congenic (CGG-repeat knock-in) mouse model using 57 wild-type and 97 expanded-CGG-repeat mice carrying up to ~250 CGG repeats. While Fmr1 message levels increased with repeat length, FMRP levels trended downward over the same range, subject to significant inter-subject variation. Human comparisons of protein levels in the frontal cortex of 7 normal and 17 FXTAS individuals revealed that the mild FMRP decrease in mice mirrored the more limited data for FMRP expression in the human samples. In addition, FMRP expression levels varied in a subset of mice across the cerebellum, frontal cortex, and hippocampus, as well as at different ages. These results provide a foundation for understanding both the CGG-repeat-dependence of FMRP expression and for interpreting clinical phenotypes in premutation carriers in terms of the balance between elevated mRNA and lowered FMRP expression levels.
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Affiliation(s)
- Anna Lisa Ludwig
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, USA
| | - Glenda M Espinal
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, USA
| | - Dalyir I Pretto
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, USA, MIND Institute, University of California, Davis, Health System, Sacramento, CA, USA and
| | - Amanda L Jamal
- Department of Neurological Surgery, University of California, Davis, School of Medicine, Davis, CA, USA
| | - Gloria Arque
- Department of Neurological Surgery, University of California, Davis, School of Medicine, Davis, CA, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, USA, MIND Institute, University of California, Davis, Health System, Sacramento, CA, USA and
| | - Robert F Berman
- MIND Institute, University of California, Davis, Health System, Sacramento, CA, USA and Department of Neurological Surgery, University of California, Davis, School of Medicine, Davis, CA, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, USA, MIND Institute, University of California, Davis, Health System, Sacramento, CA, USA and
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16
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von Leden RE, Curley LC, Greenberg GD, Hunsaker MR, Willemsen R, Berman RF. Reduced activity-dependent protein levels in a mouse model of the fragile X premutation. Neurobiol Learn Mem 2014; 109:160-8. [PMID: 24462720 DOI: 10.1016/j.nlm.2014.01.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 01/13/2014] [Accepted: 01/16/2014] [Indexed: 11/26/2022]
Abstract
Environmental enrichment results in increased levels of Fmrp in brain and increased dendritic complexity. The present experiment evaluated activity-dependent increases in Fmrp levels in the motor cortex in response to training on a skilled forelimb reaching task in the CGG KI mouse model of the fragile X premutation. Fmrp, Arc, and c-Fos protein levels were quantified by Western blot in the contralateral motor cortex of mice following training to reach for sucrose pellets with a non-preferred paw and compared to levels in the ipsilateral motor cortex. After training, all mice showed increases in Fmrp, Arc, and c-Fos protein levels in the contralateral compared to the ipsilateral hemisphere; however, the increase in CGG KI mice was less than wildtype mice. Increases in Fmrp and Arc proteins scaled with learning, whereas this relationship was not observed with the c-Fos levels. These data suggest the possibility that reduced levels of activity-dependent proteins associated with synaptic plasticity such as Fmrp and Arc may contribute to the neurocognitive phenotype reported in the CGG KI mice and the fragile X premutation.
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Affiliation(s)
- Ramona E von Leden
- Department of Neurological Surgery, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Lindsey C Curley
- Department of Neurological Surgery, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Gian D Greenberg
- Department of Psychology, University of California, Davis, Davis, CA, USA
| | - Michael R Hunsaker
- Department of Neurological Surgery, School of Medicine, University of California, Davis, Davis, CA, USA.
| | - Rob Willemsen
- CBG-Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands; NeuroTherapeutic Research Institute, University of California, Davis, Davis, CA, USA
| | - Robert F Berman
- Department of Neurological Surgery, School of Medicine, University of California, Davis, Davis, CA, USA; NeuroTherapeutic Research Institute, University of California, Davis, Davis, CA, USA
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17
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Shelton AL, Cornish K, Kraan C, Georgiou-Karistianis N, Metcalfe SA, Bradshaw JL, Hocking DR, Archibald AD, Cohen J, Trollor JN, Fielding J. Exploring inhibitory deficits in female premutation carriers of fragile X syndrome: through eye movements. Brain Cogn 2014; 85:201-8. [PMID: 24424424 DOI: 10.1016/j.bandc.2013.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 01/21/2023]
Abstract
There is evidence which demonstrates that a subset of males with a premutation CGG repeat expansion (between 55 and 200 repeats) of the fragile X mental retardation 1 gene exhibit subtle deficits of executive function that progressively deteriorate with increasing age and CGG repeat length. However, it remains unclear whether similar deficits, which may indicate the onset of more severe degeneration, are evident in female PM-carriers. In the present study we explore whether female PM-carriers exhibit deficits of executive function which parallel those of male PM-carriers. Fourteen female fragile X premutation carriers without fragile X-associated tremor/ataxia syndrome and fourteen age, sex, and IQ matched controls underwent ocular motor and neuropsychological tests of select executive processes, specifically of response inhibition and working memory. Group comparisons revealed poorer inhibitory control for female premutation carriers on ocular motor tasks, in addition to demonstrating some difficulties in behaviour self-regulation, when compared to controls. A negative correlation between CGG repeat length and antisaccade error rates for premutation carriers was also found. Our preliminary findings indicate that impaired inhibitory control may represent a phenotype characteristic which may be a sensitive risk biomarker within this female fragile X premutation population.
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Affiliation(s)
- Annie L Shelton
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Kim Cornish
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Claudine Kraan
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Nellie Georgiou-Karistianis
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Sylvia A Metcalfe
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria 3025, Australia
| | - John L Bradshaw
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Darren R Hocking
- Olga Tennison Autism Research Centre, School of Psychological Science, La Trobe University, Bundoora 3086, Australia
| | - Alison D Archibald
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, Victoria 3025, Australia; Victorian Clinical Genetics Services, Flemington Rd, Parkville, Victoria 3052, Australia
| | - Jonathan Cohen
- Genetics Education and Health Research, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria 3052, Australia; Centre for Developmental Disability Health Victoria, Monash University, Clayton, Victoria 3800, Australia; Fragile X Alliance Inc., Clinic and Resource Centre, 263 Glen Eira Road, North Caulfield, Victoria 3161, Australia
| | - Julian N Trollor
- Department of Developmental Disability Neuropsychiatry and Centre for Health Brain Ageing, School of Psychiatry, University of New South Wales, Sydney 2052, Australia
| | - Joanne Fielding
- School of Psychiatry and Psychology, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, Victoria 3800, Australia.
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18
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Wong LM, Goodrich-Hunsaker NJ, McLennan YA, Tassone F, Rivera SM, Simon TJ. A cross-sectional analysis of orienting of visuospatial attention in child and adult carriers of the fragile X premutation. J Neurodev Disord 2014; 6:45. [PMID: 25937844 PMCID: PMC4416306 DOI: 10.1186/1866-1955-6-45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 11/15/2014] [Indexed: 11/13/2022] Open
Abstract
Background Fragile X premutation carriers (fXPCs) have an expansion of 55–200 CGG repeats in the FMR1 gene. Male fXPCs are at risk for developing a neurodegenerative motor disorder (fragile X-associated tremor/ataxia syndrome (FXTAS)) often accompanied by cognitive decline. Several broad domains are implicated as core systems of dysfunction in fXPCs, including perceptual processing of spatial information, orienting of attention to space, and inhibiting attention to irrelevant distractors. We tested whether orienting of spatial attention is impaired in fXPCs. Methods Participants were fXPCs or healthy controls (HCs) asymptomatic for FXTAS. In experiment 1, they were male and female children and adults (aged 7–45 years). They oriented attention in response to volitional (endogenous) and reflexive (exogenous) cues. In experiment 2, the participants were men (aged 18–48 years). They oriented attention in an endogenous cueing task that manipulated the amount of information in the cue. Results In women, fXPCs exhibited slower reaction times than HCs in both the endogenous and exogenous conditions. In men, fXPCs exhibited slower reaction times than HCs in the exogenous condition and in the challenging endogenous cueing task with probabilistic cues. In children, fXPCs did not differ from HCs. Conclusions Because adult fXPCs were slower even when controlling for psychomotor speed, results support the interpretation that a core dysfunction in fXPCs is the allocation of spatial attention, while perceptual processing and attention orienting are intact. These findings indicate the importance of considering age and sex when interpreting and generalizing studies of fXPCs.
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Affiliation(s)
- Ling M Wong
- Davis Medical Center, MIND Institute, University of California, Sacramento, CA 95817 USA ; War Related Illness and Injury Study Center, Veterans Affairs Medical Center, Washington, DC 20422 USA
| | | | - Yingratana A McLennan
- Davis Medical Center, MIND Institute, University of California, Sacramento, CA 95817 USA
| | - Flora Tassone
- Davis Medical Center, MIND Institute, University of California, Sacramento, CA 95817 USA ; Department of Biochemistry and Molecular Medicine, University of California, Davis Medical Center, Sacramento, CA 95817 USA
| | - Susan M Rivera
- Davis Medical Center, MIND Institute, University of California, Sacramento, CA 95817 USA ; Department of Psychology, University of California, Davis, CA 95616 USA ; Center for Mind and Brain, University of California, Davis, CA 95616 USA
| | - Tony J Simon
- Davis Medical Center, MIND Institute, University of California, Sacramento, CA 95817 USA ; Department of Psychiatry and Behavioral Sciences, University of California, Davis Medical Center, Sacramento, CA 95817 USA
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19
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Hunsaker MR. Neurocognitive endophenotypes in CGG KI and Fmr1 KO mouse models of Fragile X-Associated disorders: an analysis of the state of the field. F1000Res 2013; 2:287. [PMID: 24627796 PMCID: PMC3945770 DOI: 10.12688/f1000research.2-287.v1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/23/2013] [Indexed: 12/31/2022] Open
Abstract
It has become increasingly important that the field of behavioral genetics identifies not only the gross behavioral phenotypes associated with a given mutation, but also the behavioral endophenotypes that scale with the dosage of the particular mutation being studied. Over the past few years, studies evaluating the effects of the polymorphic CGG trinucleotide repeat on the
FMR1 gene underlying Fragile X-Associated Disorders have reported preliminary evidence for a behavioral endophenotype in human Fragile X Premutation carrier populations as well as the CGG knock-in (KI) mouse model. More recently, the behavioral experiments used to test the CGG KI mouse model have been extended to the
Fmr1 knock-out (KO) mouse model. When combined, these data provide compelling evidence for a clear neurocognitive endophenotype in the mouse models of Fragile X-Associated Disorders such that behavioral deficits scale predictably with genetic dosage. Similarly, it appears that the CGG KI mouse effectively models the histopathology in Fragile X-Associated Disorders across CGG repeats well into the full mutation range, resulting in a reliable histopathological endophenotype. These endophenotypes may influence future research directions into treatment strategies for not only Fragile X Syndrome, but also the Fragile X Premutation and Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS).
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Affiliation(s)
- Michael R Hunsaker
- Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, UT, USA
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20
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Reduced excitatory amino acid transporter 1 and metabotropic glutamate receptor 5 expression in the cerebellum of fragile X mental retardation gene 1 premutation carriers with fragile X-associated tremor/ataxia syndrome. Neurobiol Aging 2013; 35:1189-97. [PMID: 24332449 DOI: 10.1016/j.neurobiolaging.2013.11.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 10/31/2013] [Accepted: 11/10/2013] [Indexed: 11/23/2022]
Abstract
A premutation (PM) expansion (55-200 CGG) in the fragile X mental retardation gene 1 causes elevated messenger RNA and reduced fragile X mental retardation gene 1 protein. Young PM carriers can develop characteristic physical features and mild cognitive disabilities. In addition, individuals with PM, particularly male carriers, are at high risk to develop fragile X-associated tremor/ataxia syndrome (FXTAS) with aging. Human postmortem FXTAS brains show extensive white matter disease in the cerebellum and the presence of intranuclear inclusions throughout the brain, although their etiologic significance is unknown. In the current work, expression levels of the metabotropic glutamate (Glu) receptor 5 and the Glu transporter excitatory amino acid transporter 1, examined by reverse transcription polymerase chain reaction and western blot analyses, were found to be reduced in the postmortem cerebellum of PM carriers with FXTAS compared with age matched controls, with higher CGG repeat number having greater reductions in both proteins. These data suggests a dysregulation of Glu signaling in PM carriers, which would likely contribute to the development and severity of FXTAS.
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21
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Cognitive-motor interference during postural control indicates at-risk cerebellar profiles in females with the FMR1 premutation. Behav Brain Res 2013; 253:329-36. [PMID: 23896050 DOI: 10.1016/j.bbr.2013.07.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/16/2013] [Accepted: 07/20/2013] [Indexed: 11/22/2022]
Abstract
Recent investigations report a higher risk of motor symptoms in females with the FMR1 premutation (PM-carriers) than has hitherto been appreciated. Here we examined basic sensorimotor and postural control under different sensory and attentional dual-task demands. Physiological performance and postural sway measures from the Physiological Profile Assessment (Lord et al., 2003 [39]) were conducted in 28 female PM-carriers (mean age: 41.32±8.03) and 31 female controls with normal FMR1 alleles (mean age: 41.61±8.3). Multiple regression analyses were conducted to examine the moderating role of CGG-repeat length on the relation between age and postural sway under dual-task interference. In female PM-carriers, our results showed significantly poorer proprioceptive awareness, slower reaction time, and greater postural displacement when performing a concurrent verbal fluency task. Significantly, these findings showed age- and genetically-modulated changes in dual-task postural displacement in the medio-lateral direction in female PM-carriers. These findings highlight the sensitivity of postural control paradigms in identifying early cerebellar postural changes that may act as surrogate markers of future decline in female PM-carriers.
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22
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Fragile X-associated tremor/ataxia syndrome (FXTAS): pathology and mechanisms. Acta Neuropathol 2013; 126:1-19. [PMID: 23793382 DOI: 10.1007/s00401-013-1138-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 05/30/2013] [Indexed: 12/17/2022]
Abstract
Since its discovery in 2001, our understanding of fragile X-associated tremor/ataxia syndrome (FXTAS) has undergone a remarkable transformation. Initially characterized rather narrowly as an adult-onset movement disorder, the definition of FXTAS is broadening; moreover, the disorder is now recognized as only one facet of a much broader clinical pleiotropy among children and adults who carry premutation alleles of the FMR1 gene. Furthermore, the intranuclear inclusions of FXTAS, once thought to be a CNS-specific marker of the disorder, are now known to be widely distributed in multiple non-CNS tissues; this observation fundamentally changes our concept of the disease, and may provide the basis for understanding the diverse medical problems associated with the premutation. Recent work on the pathogenic mechanisms underlying FXTAS indicates that the origins of the late-onset neurodegenerative disorder actually lie in early development, raising the likelihood that all forms of clinical involvement among premutation carriers have a common underlying mechanistic basis. There has also been great progress in our understanding of the triggering event(s) in FXTAS pathogenesis, which is now thought to involve sequestration of one or more nuclear proteins involved with microRNA biogenesis. Moreover, there is mounting evidence that mitochondrial dysregulation contributes to the decreased cell function and loss of viability, evident in mice even during the neonatal period. Taken together, these recent findings offer hope for early interventions for FXTAS, well before the onset of overt disease, and for the treatment of other forms of clinical involvement among premutation carriers.
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Hunsaker MR. The importance of considering all attributes of memory in behavioral endophenotyping of mouse models of genetic disease. Behav Neurosci 2013; 126:371-80. [PMID: 22642882 DOI: 10.1037/a0028453] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In order to overcome difficulties in evaluating cognitive function in mouse models of genetic disorders, it is critical to take into account the background strain of the mouse and reported phenotypes in the clinical population being studied. Recent studies have evaluated cognitive function across a number of background strains and found that spatial memory assayed by the water maze and contextual fear conditioning often does not provide optimal results. The logical extension to these results is to emphasize not only spatial, but all attributes or domains of memory function in behavioral phenotyping experiments. A careful evaluation of spatial, temporal, sensory/perceptual, affective, response, executive, proto-linguistic, and social behaviors designed to specifically evaluate the cognitive function each mouse model can be performed in a rapid, relatively high throughput manner. Such results would not only provide a more comprehensive snapshot of brain function in mouse disease models than the more common approach that approaches nonspecific spatial memory tasks to evaluate cognition, but also would better model the disorders being studied.
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Affiliation(s)
- Michael R Hunsaker
- Department of Neurological Surgery, University of California, Davis, CA 95616, USA.
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Neurobehavioural evidence for the involvement of the FMR1 gene in female carriers of fragile X syndrome. Neurosci Biobehav Rev 2013; 37:522-47. [DOI: 10.1016/j.neubiorev.2013.01.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 12/11/2012] [Accepted: 01/06/2013] [Indexed: 12/19/2022]
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Koenig CM, Lango J, Pessah IN, Berman RF. Maternal transfer of BDE-47 to offspring and neurobehavioral development in C57BL/6J mice. Neurotoxicol Teratol 2012; 34:571-80. [PMID: 23022914 DOI: 10.1016/j.ntt.2012.09.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 09/07/2012] [Accepted: 09/21/2012] [Indexed: 02/03/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are flame retardants used worldwide in a variety of commercial goods, and are now widely found in both environmental and biological samples. BDE-47 is one of the most pervasive of these PBDE congeners and therefore is of particular concern. In this study C57BL/6J mice were exposed perinatally to 0.03, 0.1 or 1mg/kg/day of BDE-47, a dose range chosen to encompass human exposure levels. Tissue levels of BDE-47 were measured in the blood, brain, fat and milk of dams and in whole fetal homogenate and blood and brain of pups on gestational day (GD) 15, and postnatal days (PNDs) 1, 10 and 21. From GD 15 to PND 1 levels of BDE-47 increased within dam tissues and then decreased from PNDs 1 to 21. Over the period of lactation levels in dam milk were comparatively high when compared to both brain and blood for all dose groups. Measurable levels of BDE-47 were found in the fetus on GD 15 confirming gestational exposure. From PNDs 1 to 21, levels of BDE-47 in pup tissue increased over the period of lactation due to the transfer of BDE-47 through milk. Behavioral tests of fine motor function and learning and memory were carried out between postnatal weeks 5-17 in order to evaluate the neurobehavioral toxicity of BDE-47. Behavioral deficits were only seen in the Barnes spatial maze where mice in the three exposure groups had longer latencies and traveled longer distances to find the escape hole when compared to vehicle control mice. These results support the conclusions that perinatal exposure to BDE-47 can have neurodevelopmental consequences, and that lactational exposure represents a significant exposure risk during development.
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Affiliation(s)
- Claire M Koenig
- Center for Children's Environmental Health, University of California Davis, Davis, CA 95616, USA.
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Kaplan ES, Cao Z, Hulsizer S, Tassone F, Berman RF, Hagerman PJ, Pessah IN. Early mitochondrial abnormalities in hippocampal neurons cultured from Fmr1 pre-mutation mouse model. J Neurochem 2012; 123:613-21. [PMID: 22924671 DOI: 10.1111/j.1471-4159.2012.07936.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 07/26/2012] [Accepted: 08/14/2012] [Indexed: 12/01/2022]
Abstract
Pre-mutation CGG repeat expansions (55-200 CGG repeats; pre-CGG) within the fragile-X mental retardation 1 (FMR1) gene cause fragile-X-associated tremor/ataxia syndrome in humans. Defects in neuronal morphology, early migration, and electrophysiological activity have been described despite appreciable expression of fragile-X mental retardation protein (FMRP) in a pre-CGG knock-in (KI) mouse model. The triggers that initiate and promote pre-CGG neuronal dysfunction are not understood. The absence of FMRP in a Drosophila model of fragile-X syndrome was shown to increase axonal transport of mitochondria. In this study, we show that dissociated hippocampal neuronal culture from pre-CGG KI mice (average 170 CGG repeats) express 42.6% of the FMRP levels and 3.8-fold higher Fmr1 mRNA than that measured in wild-type neurons at 4 days in vitro. Pre-CGG hippocampal neurons show abnormalities in the number, mobility, and metabolic function of mitochondria at this early stage of differentiation. Pre-CGG hippocampal neurites contained significantly fewer mitochondria and greatly reduced mitochondria mobility. In addition, pre-CGG neurons had higher rates of basal oxygen consumption and proton leak. We conclude that deficits in mitochondrial trafficking and metabolic function occur despite the presence of appreciable FMRP expression and may contribute to the early pathophysiology in pre-CGG carriers and to the risk of developing clinical fragile-X-associated tremor/ataxia syndrome.
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Affiliation(s)
- Eitan S Kaplan
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Berman RF, Murray KD, Arque G, Hunsaker MR, Wenzel HJ. Abnormal dendrite and spine morphology in primary visual cortex in the CGG knock-in mouse model of the fragile X premutation. Epilepsia 2012; 53 Suppl 1:150-60. [PMID: 22612820 DOI: 10.1111/j.1528-1167.2012.03486.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The fragile X mental retardation 1 gene (Fmr1) is polymorphic for CGG trinucleotide repeat number in the 5'-untranslated region, with repeat lengths <45 associated with typical development and repeat lengths >200 resulting in hypermethylation and transcriptional silencing of the gene and mental retardation in the fragile X Syndrome (FXS). Individuals with CGG repeat expansions between 55 and 200 are carriers of the fragile X premutation (PM). PM carriers show a phenotype that can include anxiety, depression, social phobia, and memory deficits. They are also at risk for developing fragile X-associated tremor/ataxia syndrome (FXTAS), a late onset neurodegenerative disorder characterized by tremor, ataxia, cognitive impairment, and neuropathologic features including intranuclear inclusions in neurons and astrocytes, loss of Purkinje cells, and white matter disease. However, very little is known about dendritic morphology in PM or in FXTAS. Therefore, we carried out a Golgi study of dendritic complexity and dendritic spine morphology in layer II/III pyramidal neurons in primary visual cortex in a knock-in (KI) mouse model of the PM. These CGG KI mice carry an expanded CGG trinucleotide repeat on Fmr1, and model many features of the PM and FXTAS. Compared to wild-type (WT) mice, CGG KI mice showed fewer dendritic branches proximal to the soma, reduced total dendritic length, and a higher frequency of longer dendritic spines. The distribution of morphologic spine types (e.g., stubby, mushroom, filopodial) did not differ between WT and KI mice. These findings demonstrate that synaptic circuitry is abnormal in visual cortex of mice used to model the PM, and suggest that such changes may underlie neurologic features found in individuals carrying the PM as well as in individuals with FXTAS.
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Affiliation(s)
- Robert F Berman
- Department of Neurological Surgery, School of Medicine, University of California-Davis, One Shields Avenue, Davis, CA 95616-8519, U.S.A.
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Distribution and frequency of intranuclear inclusions in female CGG KI mice modeling the fragile X premutation. Brain Res 2012; 1472:124-37. [PMID: 22796595 DOI: 10.1016/j.brainres.2012.06.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 06/12/2012] [Accepted: 06/29/2012] [Indexed: 11/21/2022]
Abstract
The fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder caused by CGG trinucleotide repeat expansions in the fragile X mental retardation 1 (FMR1) gene. The neuropathological hallmark of FXTAS is the presence of ubiquitin-positive intranuclear inclusions in neurons and in astroglia. Intranuclear inclusions have also been reported in the neurons of male CGG KI mice carrying an expanded CGG trinucleotide repeat and used to model FXTAS, but no study has been carried out quantifying inclusions in female CGG KI mice heterozygous for the fragile X premutation. We used histologic and immunocytochemical methods to determine the pathological features of intranuclear inclusions in astroglia and neurons. In female CGG KI mice, ubiquitin-positive intranuclear inclusions were found in neurons and astroglia throughout the brain in cortical and subcortical regions. These inclusions increased in number and became larger with advanced age and increasing CGG repeat length, supporting hypotheses that these pathologic features are progressive across the lifespan. The number of inclusions in neurons was reduced by ∼25% in female CGG KI mice compared to male CGG KI mice, but not so low as the 50% predicted. These data emphasize the need to evaluate the neurocognitive and pathological features in female carriers of the fragile X premutation with and without FXTAS symptomatology is warranted, as this population shows similar neuropathological features present in male FXTAS patients.
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Hunsaker MR, Kim K, Willemsen R, Berman RF. CGG trinucleotide repeat length modulates neural plasticity and spatiotemporal processing in a mouse model of the fragile X premutation. Hippocampus 2012; 22:2260-75. [PMID: 22707411 DOI: 10.1002/hipo.22043] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2012] [Indexed: 02/06/2023]
Abstract
The fragile X premutation is a CGG repeat expansion on the FMR1 gene between 55 and 200 repeats in length. It has been proposed that impaired spatiotemporal function underlies cognitive deficits in genetic disorders, including the fragile X premutation. This study characterized the role of the premutation for cognitive function by demonstrating CGG KI mice with 70-198 CGG repeats show deficits across tasks requiring spatial and temporal pattern separation. To elucidate mechanisms whereby CGG repeats affect spatiotemporal processing, hippocampal slices were evaluated for LTP, LTD, and mGluR1/5 LTD. Increasing CGG repeat length modulated the induction of LTP, LTD, and mGluR1/5 LTD, as well as behavioral tasks emphasizing spatiotemporal processing. Despite the deficits in the induction of all forms of plasticity, there were no differences in expression of plasticity once evoked. These data provide evidence for a neurocognitive endophenotype in the CGG KI mouse model of the premutation in which CGG repeat length negatively modulates plasticity and spatiotemporal attention.
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Affiliation(s)
- Michael R Hunsaker
- Department of Neurological Surgery, School of Medicine, University of California- Davis, Davis, CA 95616, USA.
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30
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Spatiotemporal processing deficits in female CGG KI mice modeling the fragile X premutation. Behav Brain Res 2012; 233:29-34. [PMID: 22561129 DOI: 10.1016/j.bbr.2012.04.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 04/12/2012] [Accepted: 04/20/2012] [Indexed: 01/05/2023]
Abstract
The fragile X premutation is a tandem CGG trinucleotide repeat expansion in the fragile X mental retardation 1 (FMR1) gene between 55 and 200 repeats in length. A CGG knock-in (CGG KI) mouse has been developed that models the neuropathology and cognitive deficits reported in fragile X premutation carriers. It has been suggested that carriers of the premutation demonstrate a spatiotemporal hypergranularity, or reduced resolution of spatial and temporal processing. A temporal ordering of spatial locations task was used to evaluate the ability of CGG KI mice to process temporal and spatial information with either high or low levels of spatial interference. The results indicate that CGG KI mice showed difficulty performing a spatial novelty detection task when there were high levels of spatial interference, but were able to perform the novelty detection task when there was low spatial interference. These data suggest that CGG KI mice show reduced spatial and temporal resolution that are modulated by the dosage of the Fmr1 gene mutation, such that when behavioral tasks require mice to overcome high levels of either spatial or temporal interference, the CGG KI mice perform increasingly poorly as the CGG repeat length increases.
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Cao Z, Hulsizer S, Tassone F, Tang HT, Hagerman RJ, Rogawski MA, Hagerman PJ, Pessah IN. Clustered burst firing in FMR1 premutation hippocampal neurons: amelioration with allopregnanolone. Hum Mol Genet 2012; 21:2923-35. [PMID: 22466801 DOI: 10.1093/hmg/dds118] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Premutation CGG repeat expansions (55-200 CGG repeats; preCGG) within the fragile X mental retardation 1 (FMR1) gene cause fragile X-associated tremor/ataxia syndrome (FXTAS). Defects in neuronal morphology and migration have been described in a preCGG mouse model. Mouse preCGG hippocampal neurons (170 CGG repeats) grown in vitro develop abnormal networks of clustered burst (CB) firing, as assessed by multielectrode array recordings and clustered patterns of spontaneous Ca(2+) oscillations, neither typical of wild-type (WT) neurons. PreCGG neurons have reduced expression of vesicular GABA and glutamate (Glu) transporters (VGAT and VGLUT1, respectively), and preCGG hippocampal astrocytes display a rightward shift on Glu uptake kinetics, compared with WT. These alterations in preCGG astrocytes and neurons are associated with 4- to 8-fold elevated Fmr1 mRNA and occur despite consistent expression of fragile X mental retardation protein levels at ∼50% of WT levels. Abnormal patterns of activity observed in preCGG neurons are pharmacologically mimicked in WT neurons by addition of Glu or the mGluR1/5 agonist, dihydroxyphenylglycine, to the medium, or by inhibition of astrocytic Glu uptake with dl-threo-β-benzyloxyaspartic acid, but not by the ionotropic Glu receptor agonists, α-2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid or N-methyl-d-aspartic acid. The mGluR1 (7-(hydroxyimino)cyclopropa [b]chromen-1a-carboxylate ethyl ester) or mGluR5 (2-methyl-6-(phenylethynyl)pyridine hydrochloride) antagonists reversed CB firing. Importantly, the acute addition of the neurosteroid allopregnanolone mitigated functional impairments observed in preCGG neurons in a reversible manner. These results demonstrate abnormal mGluR1/5 signaling in preCGG neurons, which is ameliorated by mGluR1/5 antagonists or augmentation of GABA(A) receptor signaling, and identify allopregnanolone as a candidate therapeutic lead.
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Affiliation(s)
- Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, CA 95616, USA
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Fernández JJ, Martínez R, Andújar E, Pérez-Alegre M, Costa A, Bonilla-Henao V, Sobrino F, Pintado CÓ, Pintado E. Gene expression profiles in the cerebellum of transgenic mice over expressing the human FMR1 gene with CGG repeats in the normal range. GENETICS AND MOLECULAR RESEARCH 2012; 11:467-83. [PMID: 22427040 DOI: 10.4238/2012.march.1.4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Modifications in the GABA pathway are considered to be responsible for motor alterations in animal models for fragile X-associated tremor ataxia syndrome. We analyzed the expression profile in the cerebellum in a transgenic mouse model that over expresses the human FMR1 gene with CGG repeats in the normal range. We used the "GeneChip Mouse Gene 1.0 ST Array" from Affymetrix analyzing 28,853 well-described and -characterized genes. Based on data from the comparative analysis of the expression profile, we detected a significant gradient with a P value <0.1 and changes in expression equal to or greater than 1.5 times compared to the control mouse genes. There were significant changes in the expression of 104 genes, among which 72% had decreased and 28% had increased expression. With the exception of GabarapL2, no changes in expression of genes from the GABA pathway were observed, which may explain the absence of an altered motor phenotype in these mice. These results further support the view that toxic effects in fragile X-associated tremor ataxia syndrome are due to expansion of CGG repeats rather than increased mRNA levels, since in the transgenic mice the FMR1 mRNA levels were increased 20-100 times compared with those of control littermates.
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Affiliation(s)
- J J Fernández
- Department of Medical Biochemistry and Molecular Biology, University Hospital Virgen Macarena, University of Seville, Spain
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Hunsaker MR. Comprehensive neurocognitive endophenotyping strategies for mouse models of genetic disorders. Prog Neurobiol 2012; 96:220-41. [PMID: 22266125 PMCID: PMC3289520 DOI: 10.1016/j.pneurobio.2011.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 12/06/2011] [Accepted: 12/20/2011] [Indexed: 01/21/2023]
Abstract
There is a need for refinement of the current behavioral phenotyping methods for mouse models of genetic disorders. The current approach is to perform a behavioral screen using standardized tasks to define a broad phenotype of the model. This phenotype is then compared to what is known concerning the disorder being modeled. The weakness inherent in this approach is twofold: First, the tasks that make up these standard behavioral screens do not model specific behaviors associated with a given genetic mutation but rather phenotypes affected in various genetic disorders; secondly, these behavioral tasks are insufficiently sensitive to identify subtle phenotypes. An alternate phenotyping strategy is to determine the core behavioral phenotypes of the genetic disorder being studied and develop behavioral tasks to evaluate specific hypotheses concerning the behavioral consequences of the genetic mutation. This approach emphasizes direct comparisons between the mouse and human that facilitate the development of neurobehavioral biomarkers or quantitative outcome measures for studies of genetic disorders across species.
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Affiliation(s)
- Michael R Hunsaker
- Department of Neurological Surgery, University of California, Davis, Davis, CA 95616, USA.
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Vinueza Veloz MF, Buijsen RAM, Willemsen R, Cupido A, Bosman LWJ, Koekkoek SKE, Potters JW, Oostra BA, De Zeeuw CI. The effect of an mGluR5 inhibitor on procedural memory and avoidance discrimination impairments in Fmr1 KO mice. GENES BRAIN AND BEHAVIOR 2012; 11:325-31. [PMID: 22257369 PMCID: PMC3491868 DOI: 10.1111/j.1601-183x.2011.00763.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability. Patients with FXS do not only suffer from cognitive problems, but also from abnormalities/deficits in procedural memory formation. It has been proposed that a lack of fragile X mental retardation protein (FMRP) leads to altered long-term plasticity by deregulation of various translational processes at the synapses, and that part of these impairments might be rescued by the inhibition of type I metabotropic glutamate receptors (mGluRs). We recently developed the Erasmus Ladder, which allows us to test, without any invasive approaches, simultaneously, both procedural memory formation and avoidance behavior during unperturbed and perturbed locomotion in mice. Here, we investigated the impact of a potent and selective mGluR5 inhibitor (Fenobam) on the behavior of Fmr1 KO mice during the Erasmus Ladder task. Fmr1 KO mice showed deficits in associative motor learning as well as avoidance behavior, both of which were rescued by intraperitoneal administration of Fenobam. While the Fmr1 KO mice did benefit from the treatment, control littermates suffered from a significant negative side effect in that their motor learning skills, but not their avoidance behavior, were significantly affected. On the basis of these studies in the FXS animal model, it may be worthwhile to investigate the effects of mGluR inhibitors on both the cognitive functions and procedural skills in FXS patients. However, the use of mGluR inhibitors appears to be strongly contraindicated in healthy controls or non-FXS patients with intellectual disability.
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Affiliation(s)
- M F Vinueza Veloz
- Department of Neuroscience, Erasmus Medical Center, Rotterdam Netherlands
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Female CGG knock-in mice modeling the fragile X premutation are impaired on a skilled forelimb reaching task. Neurobiol Learn Mem 2011; 97:229-34. [PMID: 22202169 DOI: 10.1016/j.nlm.2011.12.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 11/18/2011] [Accepted: 12/10/2011] [Indexed: 01/20/2023]
Abstract
The fragile X premutation is a tandem CGG trinucleotide repeat expansion in the fragile X mental retardation 1 (FMR1) gene between 55 and 200 repeats in length. A CGG knock-in (CGG KI) mouse has been developed that models the neuropathology and cognitive deficits reported in fragile X premutation carriers. Previous studies have demonstrated that CGG KI mice have spatiotemporal information processing deficits and impaired visuomotor function that worsen with increasing CGG repeat length. Since skilled forelimb reaching requires integration of information from the visual and motor systems, skilled reaching performance could identify potential visuomotor dysfunction in CGG KI mice. To characterize motor deficits associated with the fragile X premutation, 6 month old female CGG KI mice heterozygous for trinucleotide repeats ranging from 70-200 CGG in length were tested for their ability to learn a skilled forelimb reaching task. The results demonstrate that female CGG KI mice show deficits for learning a skilled forelimb reaching task compared to wildtype littermates, and that these deficits worsen with increasing CGG repeat lengths.
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Hunsaker MR, Greco CM, Spath MA, Smits APT, Navarro CS, Tassone F, Kros JM, Severijnen LA, Berry-Kravis EM, Berman RF, Hagerman PJ, Willemsen R, Hagerman RJ, Hukema RK. Widespread non-central nervous system organ pathology in fragile X premutation carriers with fragile X-associated tremor/ataxia syndrome and CGG knock-in mice. Acta Neuropathol 2011; 122:467-79. [PMID: 21785977 DOI: 10.1007/s00401-011-0860-9] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/11/2011] [Accepted: 07/11/2011] [Indexed: 11/28/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder generally presenting with intention tremor and gait ataxia, but with a growing list of co-morbid medical conditions including hypothyroidism, hypertension, peripheral neuropathy, and cognitive decline. The pathological hallmark of FXTAS is the presence of intranuclear inclusions in both neurons and astroglia. However, it is unknown to what extent such inclusions are present outside the central nervous system (CNS). To address this issue, we surveyed non-CNS organs in ten human cases with FXTAS and in a CGG repeat knock-in (CGG KI) mouse model known to possess neuronal and astroglial inclusions. We find inclusions in multiple tissues from FXTAS cases and CGG KI mice, including pancreas, thyroid, adrenal gland, gastrointestinal, pituitary gland, pineal gland, heart, and mitral valve, as well as throughout the associated autonomic ganglia. Inclusions were observed in the testes, epididymis, and kidney of FXTAS cases, but were not observed in mice. These observations demonstrate extensive involvement of the peripheral nervous system and systemic organs. The finding of intranuclear inclusions in non-CNS somatic organ systems, throughout the PNS, and in the enteric nervous system of both FXTAS cases as well as CGG KI mice suggests that these tissues may serve as potential sites to evaluate early intervention strategies or be used as diagnostic factors.
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Affiliation(s)
- Michael R Hunsaker
- Department of Neurological Surgery, University of California, Davis, Davis, CA, USA
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