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D'Antoni S, Spatuzza M, Bonaccorso CM, Catania MV. Role of fragile X messenger ribonucleoprotein 1 in the pathophysiology of brain disorders: a glia perspective. Neurosci Biobehav Rev 2024; 162:105731. [PMID: 38763180 DOI: 10.1016/j.neubiorev.2024.105731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/21/2024]
Abstract
Fragile X messenger ribonucleoprotein 1 (FMRP) is a widely expressed RNA binding protein involved in several steps of mRNA metabolism. Mutations in the FMR1 gene encoding FMRP are responsible for fragile X syndrome (FXS), a leading genetic cause of intellectual disability and autism spectrum disorder, and fragile X-associated tremor-ataxia syndrome (FXTAS), a neurodegenerative disorder in aging men. Although FMRP is mainly expressed in neurons, it is also present in glial cells and its deficiency or altered expression can affect functions of glial cells with implications for the pathophysiology of brain disorders. The present review focuses on recent advances on the role of glial subtypes, astrocytes, oligodendrocytes and microglia, in the pathophysiology of FXS and FXTAS, and describes how the absence or reduced expression of FMRP in these cells can impact on glial and neuronal functions. We will also briefly address the role of FMRP in radial glial cells and its effects on neural development, and gliomas and will speculate on the role of glial FMRP in other brain disorders.
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Affiliation(s)
- S D'Antoni
- Institute for Biomedical Research and Innovation (IRIB), National Research Council (CNR), Via Paolo Gaifami 18, Catania 95126, Italy
| | - M Spatuzza
- Institute for Biomedical Research and Innovation (IRIB), National Research Council (CNR), Via Paolo Gaifami 18, Catania 95126, Italy
| | - C M Bonaccorso
- Oasi Research Institute - IRCCS, via Conte Ruggero 73, Troina 94018, Italy
| | - M V Catania
- Institute for Biomedical Research and Innovation (IRIB), National Research Council (CNR), Via Paolo Gaifami 18, Catania 95126, Italy.
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Boivin M, Charlet-Berguerand N. Trinucleotide CGG Repeat Diseases: An Expanding Field of Polyglycine Proteins? Front Genet 2022; 13:843014. [PMID: 35295941 PMCID: PMC8918734 DOI: 10.3389/fgene.2022.843014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 01/31/2022] [Indexed: 12/30/2022] Open
Abstract
Microsatellites are repeated DNA sequences of 3–6 nucleotides highly variable in length and sequence and that have important roles in genomes regulation and evolution. However, expansion of a subset of these microsatellites over a threshold size is responsible of more than 50 human genetic diseases. Interestingly, some of these disorders are caused by expansions of similar sequences, sizes and localizations and present striking similarities in clinical manifestations and histopathological features, which suggest a common mechanism of disease. Notably, five identical CGG repeat expansions, but located in different genes, are the causes of fragile X-associated tremor/ataxia syndrome (FXTAS), neuronal intranuclear inclusion disease (NIID), oculopharyngodistal myopathy type 1 to 3 (OPDM1-3) and oculopharyngeal myopathy with leukoencephalopathy (OPML), which are neuromuscular and neurodegenerative syndromes with overlapping symptoms and similar histopathological features, notably the presence of characteristic eosinophilic ubiquitin-positive intranuclear inclusions. In this review we summarize recent finding in neuronal intranuclear inclusion disease and FXTAS, where the causing CGG expansions were found to be embedded within small upstream ORFs (uORFs), resulting in their translation into novel proteins containing a stretch of polyglycine (polyG). Importantly, expression of these polyG proteins is toxic in animal models and is sufficient to reproduce the formation of ubiquitin-positive intranuclear inclusions. These data suggest the existence of a novel class of human genetic pathology, the polyG diseases, and question whether a similar mechanism may exist in other diseases, notably in OPDM and OPML.
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Zhao X, Usdin K. (Dys)function Follows Form: Nucleic Acid Structure, Repeat Expansion, and Disease Pathology in FMR1 Disorders. Int J Mol Sci 2021; 22:ijms22179167. [PMID: 34502075 PMCID: PMC8431139 DOI: 10.3390/ijms22179167] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Fragile X-related disorders (FXDs), also known as FMR1 disorders, are examples of repeat expansion diseases (REDs), clinical conditions that arise from an increase in the number of repeats in a disease-specific microsatellite. In the case of FXDs, the repeat unit is CGG/CCG and the repeat tract is located in the 5' UTR of the X-linked FMR1 gene. Expansion can result in neurodegeneration, ovarian dysfunction, or intellectual disability depending on the number of repeats in the expanded allele. A growing body of evidence suggests that the mutational mechanisms responsible for many REDs share several common features. It is also increasingly apparent that in some of these diseases the pathologic consequences of expansion may arise in similar ways. It has long been known that many of the disease-associated repeats form unusual DNA and RNA structures. This review will focus on what is known about these structures, the proteins with which they interact, and how they may be related to the causative mutation and disease pathology in the FMR1 disorders.
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Affiliation(s)
- Xiaonan Zhao
- Correspondence: (X.Z.); (K.U.); Tel.: +1-301-451-6322 (X.Z.); +1-301-496-2189 (K.U.)
| | - Karen Usdin
- Correspondence: (X.Z.); (K.U.); Tel.: +1-301-451-6322 (X.Z.); +1-301-496-2189 (K.U.)
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4
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Molecular Pathogenesis and Peripheral Monitoring of Adult Fragile X-Associated Syndromes. Int J Mol Sci 2021; 22:ijms22168368. [PMID: 34445074 PMCID: PMC8395059 DOI: 10.3390/ijms22168368] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/29/2021] [Accepted: 07/30/2021] [Indexed: 12/16/2022] Open
Abstract
Abnormal trinucleotide expansions cause rare disorders that compromise quality of life and, in some cases, lifespan. In particular, the expansions of the CGG-repeats stretch at the 5’-UTR of the Fragile X Mental Retardation 1 (FMR1) gene have pleiotropic effects that lead to a variety of Fragile X-associated syndromes: the neurodevelopmental Fragile X syndrome (FXS) in children, the late-onset neurodegenerative disorder Fragile X-associated tremor-ataxia syndrome (FXTAS) that mainly affects adult men, the Fragile X-associated primary ovarian insufficiency (FXPOI) in adult women, and a variety of psychiatric and affective disorders that are under the term of Fragile X-associated neuropsychiatric disorders (FXAND). In this review, we will describe the pathological mechanisms of the adult “gain-of-function” syndromes that are mainly caused by the toxic actions of CGG RNA and FMRpolyG peptide. There have been intensive attempts to identify reliable peripheral biomarkers to assess disease progression and onset of specific pathological traits. Mitochondrial dysfunction, altered miRNA expression, endocrine system failure, and impairment of the GABAergic transmission are some of the affectations that are susceptible to be tracked using peripheral blood for monitoring of the motor, cognitive, psychiatric and reproductive impairment of the CGG-expansion carriers. We provided some illustrative examples from our own cohort. Understanding the association between molecular pathogenesis and biomarkers dynamics will improve effective prognosis and clinical management of CGG-expansion carriers.
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Loesch DZ, Kemp BE, Bui MQ, Fisher PR, Allan CY, Sanislav O, Ngoei KRW, Atkinson A, Tassone F, Annesley SJ, Storey E. Cellular Bioenergetics and AMPK and TORC1 Signalling in Blood Lymphoblasts Are Biomarkers of Clinical Status in FMR1 Premutation Carriers. Front Psychiatry 2021; 12:747268. [PMID: 34880790 PMCID: PMC8645580 DOI: 10.3389/fpsyt.2021.747268] [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: 07/26/2021] [Accepted: 10/28/2021] [Indexed: 11/13/2022] Open
Abstract
Fragile X Associated Tremor/Ataxia Syndrome (FXTAS) is a neurodegenerative disorder affecting carriers of premutation alleles (PM) of the X-linked FMR1 gene, which contain CGG repeat expansions of 55-200 range in a non-coding region. This late-onset disorder is characterised by the presence of tremor/ataxia and cognitive decline, associated with the white matter lesions throughout the brain, especially involving the middle cerebellar peduncles. Nearly half of older male and ~ 20% of female PM carriers develop FXTAS. While there is evidence for mitochondrial dysfunction in neural and some peripheral tissues from FXTAS patients (though less obvious in the non-FXTAS PM carriers), the results from peripheral blood mononuclear cells (PBMC) are still controversial. Motor, cognitive, and neuropsychiatric impairments were correlated with measures of mitochondrial and non-mitochondrial respiratory activity, AMPK, and TORC1 cellular stress-sensing protein kinases, and CGG repeat size, in a sample of adult FXTAS male and female carriers. Moreover, the levels of these cellular measures, all derived from Epstein- Barr virus (EBV)- transformed and easily accessible blood lymphoblasts, were compared between the FXTAS (N = 23) and non-FXTAS (n = 30) subgroups, and with baseline data from 33 healthy non-carriers. A significant hyperactivity of cellular bioenergetics components as compared with the baseline data, more marked in the non-FXTAS PMs, was negatively correlated with repeat numbers at the lower end of the CGG-PM distribution. Significant associations of these components with motor impairment measures, including tremor-ataxia and parkinsonism, and neuropsychiatric changes, were prevalent in the FXTAS subgroup. Moreover, a striking elevation of AMPK activity, and a decrease in TORC1 levels, especially in the non-FXTAS carriers, were related to the size of CGG expansion. The bioenergetics changes in blood lymphoblasts are biomarkers of the clinical status of FMR1 carriers. The relationship between these changes and neurological involvement in the affected carriers suggests that brain bioenergetic alterations are reflected in this peripheral tissue. A possible neuroprotective role of stress sensing kinase, AMPK, in PM carriers, should be addressed in future longitudinal studies. A decreased level of TORC1-the mechanistic target of the rapamycin complex, suggests a possible future approach to therapy in FXTAS.
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Affiliation(s)
- Danuta Z Loesch
- School of Psychology and Public Health, La Trobe University, Bundoora, VA, Australia
| | - Bruce E Kemp
- Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VA, Australia.,St. Vincent's Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VA, Australia
| | - Minh Q Bui
- Centre for Molecular, Environmental, Genetic and Analytic, Epidemiology, University of Melbourne, Parkville, VA, Australia
| | - Paul R Fisher
- Department of Physiology Anatomy and Microbiology, La Trobe University, Bundoora, VA, Australia
| | - Claire Y Allan
- Department of Physiology Anatomy and Microbiology, La Trobe University, Bundoora, VA, Australia
| | - Oana Sanislav
- Department of Physiology Anatomy and Microbiology, La Trobe University, Bundoora, VA, Australia
| | - Kevin R W Ngoei
- St. Vincent's Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VA, Australia
| | - Anna Atkinson
- School of Psychology and Public Health, La Trobe University, Bundoora, VA, Australia
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA, United States.,Department of Biochemistry and Molecular Medicine M.I.N.D. Institute, University of California Davis Medical Center, Davis, Sacramento, CA, United States
| | - Sarah J Annesley
- Department of Physiology Anatomy and Microbiology, La Trobe University, Bundoora, VA, Australia
| | - Elsdon Storey
- Department of Medicine (Neuroscience), Monash University, Alfred Hospital Campus, Melbourne, VIC, Australia
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Potokar M, Morita M, Wiche G, Jorgačevski J. The Diversity of Intermediate Filaments in Astrocytes. Cells 2020; 9:E1604. [PMID: 32630739 PMCID: PMC7408014 DOI: 10.3390/cells9071604] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/26/2020] [Accepted: 07/01/2020] [Indexed: 01/02/2023] Open
Abstract
Despite the remarkable complexity of the individual neuron and of neuronal circuits, it has been clear for quite a while that, in order to understand the functioning of the brain, the contribution of other cell types in the brain have to be accounted for. Among glial cells, astrocytes have multiple roles in orchestrating neuronal functions. Their communication with neurons by exchanging signaling molecules and removing molecules from extracellular space takes place at several levels and is governed by different cellular processes, supported by multiple cellular structures, including the cytoskeleton. Intermediate filaments in astrocytes are emerging as important integrators of cellular processes. Astrocytes express five types of intermediate filaments: glial fibrillary acidic protein (GFAP); vimentin; nestin; synemin; lamins. Variability, interactions with different cellular structures and the particular roles of individual intermediate filaments in astrocytes have been studied extensively in the case of GFAP and vimentin, but far less attention has been given to nestin, synemin and lamins. Similarly, the interplay between different types of cytoskeleton and the interaction between the cytoskeleton and membranous structures, which is mediated by cytolinker proteins, are understudied in astrocytes. The present review summarizes the basic properties of astrocytic intermediate filaments and of other cytoskeletal macromolecules, such as cytolinker proteins, and describes the current knowledge of their roles in normal physiological and pathological conditions.
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Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia;
- Celica BIOMEDICAL, 1000 Ljubljana, Slovenia;
| | - Mitsuhiro Morita
- Department of Biology, Kobe University Graduate School of Science, Kobe 657-8501, Japan;
| | - Gerhard Wiche
- Celica BIOMEDICAL, 1000 Ljubljana, Slovenia;
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology – Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia;
- Celica BIOMEDICAL, 1000 Ljubljana, Slovenia;
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Shani V, Safory H, Szargel R, Wang N, Cohen T, Elghani FA, Hamza H, Savyon M, Radzishevsky I, Shaulov L, Rott R, Lim KL, Ross CA, Bandopadhyay R, Zhang H, Engelender S. Physiological and pathological roles of LRRK2 in the nuclear envelope integrity. Hum Mol Genet 2020; 28:3982-3996. [PMID: 31626293 DOI: 10.1093/hmg/ddz245] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 09/12/2019] [Accepted: 10/03/2019] [Indexed: 01/28/2023] Open
Abstract
Mutations in LRRK2 cause autosomal dominant and sporadic Parkinson's disease, but the mechanisms involved in LRRK2 toxicity in PD are yet to be fully understood. We found that LRRK2 translocates to the nucleus by binding to seven in absentia homolog (SIAH-1), and in the nucleus it directly interacts with lamin A/C, independent of its kinase activity. LRRK2 knockdown caused nuclear lamina abnormalities and nuclear disruption. LRRK2 disease mutations mostly abolish the interaction with lamin A/C and, similar to LRRK2 knockdown, cause disorganization of lamin A/C and leakage of nuclear proteins. Dopaminergic neurons of LRRK2 G2019S transgenic and LRRK2 -/- mice display decreased circularity of the nuclear lamina and leakage of the nuclear protein 53BP1 to the cytosol. Dopaminergic nigral and cortical neurons of both LRRK2 G2019S and idiopathic PD patients exhibit abnormalities of the nuclear lamina. Our data indicate that LRRK2 plays an essential role in maintaining nuclear envelope integrity. Disruption of this function by disease mutations suggests a novel phosphorylation-independent loss-of-function mechanism that may synergize with other neurotoxic effects caused by LRRK2 mutations.
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Affiliation(s)
- Vered Shani
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Hazem Safory
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Raymonde Szargel
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ninghan Wang
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Tsipora Cohen
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Fatimah Abd Elghani
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Haya Hamza
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Mor Savyon
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Inna Radzishevsky
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Lihi Shaulov
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Ruth Rott
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Kah-Leong Lim
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Christopher A Ross
- Department of Psychiatry, The Johns Hopkins Medical School, Baltimore, MD, USA
| | | | - Hui Zhang
- Department of Neuroscience, Thomas Jefferson University, Philadelphia, PA, USA
| | - Simone Engelender
- Dept. of Biochemistry, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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An explanation of the mechanisms underlying fragile X-associated premature ovarian insufficiency. J Assist Reprod Genet 2020; 37:1313-1322. [PMID: 32377997 PMCID: PMC7311620 DOI: 10.1007/s10815-020-01774-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/01/2020] [Indexed: 12/22/2022] Open
Abstract
Fragile X and fragile X-associated tremor-ataxia syndrome (FXTAS) are caused by mutations of the FMR1 gene. The mutations causing FXTAS can expand in a generation to a "full mutation" causing fragile X syndrome. The mutations causing FXTAS and the phenotype, fragile X-associated premature ovarian insufficiency (FXPOI), are referred to as the FMR1 premutation (PM). The objective of this paper was to formulate a theory to explain the Mechanism for FXPOI.Recent research on fragile X syndrome and FXTAS has led to sophisticated theories about the mechanisms underlying these diseases. It has been proposed that similar mechanisms underlie FXPOI. Utilizing recent research on FXTAS, but a more detailed application of ovarian physiology, we present a more ovarian specific theory as to the primary mechanism explaining the development of FXPOI.The FXPOI phenotype may best be viewed as derivative of the observation that fragile X PM carriers experience menopause an average of 5 years earlier than non-carriers. Women carrying the PM experience an earlier menopause because of an accelerated activation of their primordial follicle pool. This acceleration of primordial follicle activation occurs, in part, because of diminished AMH production. AMH production is diminished because of accelerated atresia of early antral follicles. This accelerated atresia likely occurs because the fragile X PM leads to a slowing of the rate of granulosa cell mitosis in some follicles.
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Ma L, Herren AW, Espinal G, Randol J, McLaughlin B, Martinez-Cerdeño V, Pessah IN, Hagerman RJ, Hagerman PJ. Composition of the Intranuclear Inclusions of Fragile X-associated Tremor/Ataxia Syndrome. Acta Neuropathol Commun 2019; 7:143. [PMID: 31481131 PMCID: PMC6720097 DOI: 10.1186/s40478-019-0796-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 08/24/2019] [Indexed: 12/11/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder associated with a premutation repeat expansion (55-200 CGG repeats) in the 5' noncoding region of the FMR1 gene. Solitary intranuclear inclusions within FXTAS neurons and astrocytes constitute a hallmark of the disorder, yet our understanding of how and why these bodies form is limited. Here, we have discovered that FXTAS inclusions emit a distinct autofluorescence spectrum, which forms the basis of a novel, unbiased method for isolating FXTAS inclusions by preparative fluorescence-activated cell sorting (FACS). Using a combination of autofluorescence-based FACS and liquid chromatography/tandem mass spectrometry (LC-MS/MS)-based proteomics, we have identified more than two hundred proteins that are enriched within the inclusions relative to FXTAS whole nuclei. Whereas no single protein species dominates inclusion composition, highly enriched levels of conjugated small ubiquitin-related modifier 2 (SUMO 2) protein and p62/sequestosome-1 (p62/SQSTM1) protein were found within the inclusions. Many additional proteins involved with RNA binding, protein turnover, and DNA damage repair were enriched within inclusions relative to total nuclear protein. The current analysis has also allowed the first direct detection, through peptide sequencing, of endogenous FMRpolyG peptide, the product of repeat-associated non-ATG (RAN) translation of the FMR1 mRNA. However, this peptide was found only at extremely low levels and not within whole FXTAS nuclear preparations, raising the question whether endogenous RAN products exist at quantities sufficient to contribute to FXTAS pathogenesis. The abundance of the inclusion-associated ubiquitin- and SUMO-based modifiers supports a model for inclusion formation as the result of increased protein loads and elevated oxidative stress leading to maladaptive autophagy. These results highlight the need to further investigate FXTAS pathogenesis in the context of endogenous systems.
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Affiliation(s)
- Lisa Ma
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Anthony W Herren
- Genome Center, University of California Davis, Davis, California, USA
| | - Glenda Espinal
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Jamie Randol
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA
| | - Bridget McLaughlin
- Department of Pathology and Laboratory Medicine, University of California Davis, School of Medicine, Sacramento, California, USA
| | - Veronica Martinez-Cerdeño
- Department of Pathology and Laboratory Medicine, University of California Davis, School of Medicine, Sacramento, California, USA
- Institute for Pediatric Regenerative Medicine, Shriners Hospital of Northern California, University of California Davis, School of Medicine, Sacramento, California, USA
- MIND Institute, University of California Davis Health, Sacramento, California, USA
| | - Isaac N Pessah
- MIND Institute, University of California Davis Health, Sacramento, California, USA
- Department of Molecular Biosciences, University of California Davis, School of Veterinary Medicine, Davis, California, USA
| | - Randi J Hagerman
- MIND Institute, University of California Davis Health, Sacramento, California, USA
- Department of Pediatrics, University of California Davis, School of Medicine, Sacramento, California, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, One Shields Ave, Davis, CA, USA.
- MIND Institute, University of California Davis Health, Sacramento, California, USA.
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Rodriguez CM, Todd PK. New pathologic mechanisms in nucleotide repeat expansion disorders. Neurobiol Dis 2019; 130:104515. [PMID: 31229686 DOI: 10.1016/j.nbd.2019.104515] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/07/2019] [Accepted: 06/19/2019] [Indexed: 12/14/2022] Open
Abstract
Tandem microsatellite repeats are common throughout the human genome and intrinsically unstable, exhibiting expansions and contractions both somatically and across generations. Instability in a small subset of these repeats are currently linked to human disease, although recent findings suggest more disease-causing repeats await discovery. These nucleotide repeat expansion disorders (NREDs) primarily affect the nervous system and commonly lead to neurodegeneration through toxic protein gain-of-function, protein loss-of-function, and toxic RNA gain-of-function mechanisms. However, the lines between these categories have blurred with recent findings of unconventional Repeat Associated Non-AUG (RAN) translation from putatively non-coding regions of the genome. Here we review two emerging topics in NREDs: 1) The mechanisms by which RAN translation occurs and its role in disease pathogenesis and 2) How nucleotide repeats as RNA and translated proteins influence liquid-liquid phase separation, membraneless organelle dynamics, and nucleocytoplasmic transport. We examine these topics with a particular eye on two repeats: the CGG repeat expansion responsible for Fragile X syndrome and Fragile X-associated Tremor Ataxia Syndrome (FXTAS) and the intronic GGGGCC repeat expansion in C9orf72, the most common inherited cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Our thesis is that these emerging disease mechanisms can inform a broader understanding of the native roles of microsatellites in cellular function and that aberrations in these native processes provide clues to novel therapeutic strategies for these currently untreatable disorders.
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Affiliation(s)
- C M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Genetics, Stanford University, Stanford, CA, USA
| | - P K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
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Intracellular FMRpolyG-Hsp70 complex in fibroblast cells from a patient affected by fragile X tremor ataxia syndrome. Heliyon 2019; 5:e01954. [PMID: 31294106 PMCID: PMC6595188 DOI: 10.1016/j.heliyon.2019.e01954] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 05/20/2019] [Accepted: 06/13/2019] [Indexed: 01/09/2023] Open
Abstract
Background Fragile X-associated tremor/ataxia syndrome is a late-onset neurodegenerative disorder that affects about 40% of carriers of CGG-repeat expansions in the premutation range within the fragile X gene (FMR1). Main clinical features include intention tremor, cerebellar ataxia, and parkinsonism. Recently, great emphasis on the deposition of soluble aggregates produced by a RAN translation process, as main pathogenic mechanism, has been given. These aggregates contain a small protein with a polyglycine stretch on the aminoterminal end named FMRpolyG and, so far, have been isolated and characterized in drosophila and mouse models, in post mortem brain of fragile X-associated tremor/ataxia syndrome patients, in fibroblasts of fragile primary ovarian insufficiency patients, but never in fibroblasts from a fragile X-associated tremor/ataxia living patients. In adult carriers the syndrome is frequently misdiagnosed due to the lack of specific markers. Methods We standardized immunocytochemistry, immunoprecipitation and western blot procedures to study and biochemically characterize the FMRpolyG protein in fibroblasts from human skin biopsy. Results We demonstrate for the first time, in fibroblasts from a patient affected by Fragile X-associated tremor/ataxia syndrome, the presence ex vivo of inclusions consisting of FMRpolyG- Hsp70 soluble aggregates. Conclusion These observations can pave the way to develop a cellular model for studying ex vivo and in vitro the mechanisms involved in the production of FMRpolyG aggregates, their toxicity, and the role of the FMRpolyG-Hsp70 interaction in the pathogenesis of fragile X-associated tremor/ataxia syndrome.
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12
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Hoem G, Bowitz Larsen K, Øvervatn A, Brech A, Lamark T, Sjøttem E, Johansen T. The FMRpolyGlycine Protein Mediates Aggregate Formation and Toxicity Independent of the CGG mRNA Hairpin in a Cellular Model for FXTAS. Front Genet 2019; 10:249. [PMID: 30984240 PMCID: PMC6447689 DOI: 10.3389/fgene.2019.00249] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/05/2019] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a CGG-repeat expansion in the 5' UTR of the FMR1 gene on the X-chromosome. Both elevated levels of the expanded FMR1 mRNA and aberrant expression of a polyglycine protein (FMRpolyG) from the CGG-repeat region are hypothesized to trigger the pathogenesis of FXTAS. While increased expression of FMRpolyG leads to higher toxicity in FXTAS models, the pathogenic effect of this protein has only been studied in the presence of CGG-containing mRNA. Here we present a model that allows measurement of the effect of FMRpolyG-expression without co-expression of the corresponding CGG mRNA hairpin. This allows direct comparison of the effect of the FMRpolyG protein per se, vs. that of the FMRpolyG protein together with the CGG mRNA hairpin. Our results show that expression of the FMRpolyG, in the absence of any CGG mRNA, is sufficient to cause reduced cell viability, lamin ring disruption and aggregate formation. Furthermore, we found FMRpolyG to be a long-lived protein degraded primarily by the ubiquitin-proteasome-system. Together, our data indicate that accumulation of FMRpolyG protein per se may play a major role in the development of FXTAS.
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Affiliation(s)
- Gry Hoem
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Kenneth Bowitz Larsen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Aud Øvervatn
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Andreas Brech
- Department of Molecular Cell Biology, Institute for Cancer Research, Oslo University Hospital, Oslo, Norway.,Faculty of Medicine, Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Trond Lamark
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Eva Sjøttem
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
| | - Terje Johansen
- Molecular Cancer Research Group, Department of Medical Biology, University of Tromsø - The Arctic University of Norway, Tromsø, Norway
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13
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Fernández E, Gennaro E, Pirozzi F, Baldo C, Forzano F, Turolla L, Faravelli F, Gastaldo D, Coviello D, Grasso M, Bagni C. FXS-Like Phenotype in Two Unrelated Patients Carrying a Methylated Premutation of the FMR1 Gene. Front Genet 2018; 9:442. [PMID: 30450110 PMCID: PMC6224343 DOI: 10.3389/fgene.2018.00442] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 09/14/2018] [Indexed: 12/31/2022] Open
Abstract
Fragile X syndrome (FXS) is mostly caused by two distinct events that occur in the FMR1 gene (Xq27.3): an expansion above 200 repeats of a CGG triplet located in the 5′UTR of the gene, and methylation of the cytosines located in the CpG islands upstream of the CGG repeats. Here, we describe two unrelated families with one FXS child and another sibling presenting mild intellectual disability and behavioral features evocative of FXS. Genetic characterization of the undiagnosed sibling revealed mosaicism in both the CGG expansion size and the methylation levels in the different tissues analyzed. This report shows that in the same family, two siblings carrying different CGG repeats, one in the full-mutation range and the other in the premutation range, present methylation mosaicism and consequent decreased FMRP production leading to FXS and FXS-like features, respectively. Decreased FMRP levels, more than the number of repeats seem to correlate with the severity of FXS clinical phenotypes.
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Affiliation(s)
- Esperanza Fernández
- Center for Human Genetics, KU Leuven, Leuven, Belgium.,VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Elena Gennaro
- Laboratorio di Genetica Umana, Ospedali Galliera, Genoa, Italy
| | - Filomena Pirozzi
- Center for Human Genetics, KU Leuven, Leuven, Belgium.,VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium
| | - Chiara Baldo
- Laboratorio di Genetica Umana, Ospedali Galliera, Genoa, Italy
| | - Francesca Forzano
- Clinical Genetics Department, Borough Wing Guy's Hospital, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.,S.S.D. Genetica Medica, Ospedali Galliera, Genoa, Italy
| | - Licia Turolla
- U.O.S. Genetica Medica, Azienda ULSS 2, Treviso, Italy
| | - Francesca Faravelli
- Clinical Genetics Department, Great Ormond Street Hospital, London, United Kingdom
| | - Denise Gastaldo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | | | - Marina Grasso
- Laboratorio di Genetica Umana, Ospedali Galliera, Genoa, Italy
| | - Claudia Bagni
- Center for Human Genetics, KU Leuven, Leuven, Belgium.,VIB & KU Leuven Center for Brain & Disease Research, Leuven, Belgium.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy
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14
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Glineburg MR, Todd PK, Charlet-Berguerand N, Sellier C. Repeat-associated non-AUG (RAN) translation and other molecular mechanisms in Fragile X Tremor Ataxia Syndrome. Brain Res 2018; 1693:43-54. [PMID: 29453961 PMCID: PMC6010627 DOI: 10.1016/j.brainres.2018.02.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 11/11/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset inherited neurodegenerative disorder characterized by progressive intention tremor, gait ataxia and dementia associated with mild brain atrophy. The cause of FXTAS is a premutation expansion, of 55 to 200 CGG repeats localized within the 5'UTR of FMR1. These repeats are transcribed in the sense and antisense directions into mutants RNAs, which have increased expression in FXTAS. Furthermore, CGG sense and CCG antisense expanded repeats are translated into novel proteins despite their localization in putatively non-coding regions of the transcript. Here we focus on two proposed disease mechanisms for FXTAS: 1) RNA gain-of-function, whereby the mutant RNAs bind specific proteins and preclude their normal functions, and 2) repeat-associated non-AUG (RAN) translation, whereby translation through the CGG or CCG repeats leads to the production of toxic homopolypeptides, which in turn interfere with a variety of cellular functions. Here, we analyze the data generated to date on both of these potential molecular mechanisms and lay out a path forward for determining which factors drive FXTAS pathogenicity.
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Affiliation(s)
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran's Affairs Medical Center, Ann Arbor, MI 48105, USA
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
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15
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FMR1 allele size distribution in 35,000 males and females: a comparison of developmental delay and general population cohorts. Genet Med 2018; 20:1627-1634. [DOI: 10.1038/gim.2018.52] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 02/20/2018] [Indexed: 01/01/2023] Open
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16
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Boivin M, Willemsen R, Hukema RK, Sellier C. Potential pathogenic mechanisms underlying Fragile X Tremor Ataxia Syndrome: RAN translation and/or RNA gain-of-function? Eur J Med Genet 2017; 61:674-679. [PMID: 29223504 DOI: 10.1016/j.ejmg.2017.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 09/19/2017] [Accepted: 11/08/2017] [Indexed: 10/18/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disease caused by an expansion of 55-200 CGG repeats located in the FMR1 gene. The main clinical and neuropathological features of FXTAS are progressive intention tremor and gait ataxia associated with brain atrophy, neuronal cell loss and presence of ubiquitin-positive intranuclear inclusions in both neurons and astrocytes. At the molecular level, FXTAS is characterized by increased expression of FMR1 sense and antisense RNA containing expanded CGG or GGC repeats, respectively. Here, we discuss the putative molecular mechanisms underlying FXTAS and notably recent reports that expanded CGG and GGC repeats may be pathogenic through RAN translation into toxic proteins.
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Affiliation(s)
- Manon Boivin
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, 3015 CN Rotterdam, The Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, 3015 CN Rotterdam, The Netherlands
| | - Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
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17
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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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18
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Cleary JD, Ranum LP. New developments in RAN translation: insights from multiple diseases. Curr Opin Genet Dev 2017; 44:125-134. [PMID: 28365506 PMCID: PMC5951168 DOI: 10.1016/j.gde.2017.03.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 02/28/2017] [Accepted: 03/13/2017] [Indexed: 12/14/2022]
Abstract
Since the discovery of repeat-associated non-ATG (RAN) translation, and more recently its association with amyotrophic lateral sclerosis/frontotemporal dementia, there has been an intense focus to understand how this process works and the downstream effects of these novel proteins. RAN translation across several different types of repeat expansions mutations (CAG, CTG, CCG, GGGGCC, GGCCCC) results in the production of proteins in all three reading frames without an ATG initiation codon. The combination of bidirectional transcription and RAN translation has been shown to result in the accumulation of up to six mutant expansion proteins in a growing number of diseases. This process is complex mechanistically and also complex from the perspective of the downstream consequences in disease. Here we review recent developments in RAN translation and their implications on our basic understanding of neurodegenerative disease and gene expression.
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Affiliation(s)
- John Douglas Cleary
- Center for NeuroGenetics, University of Florida, Gainesville, FL, USA; Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, FL, USA; Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Laura Pw Ranum
- Center for NeuroGenetics, University of Florida, Gainesville, FL, USA; Department of Molecular Genetics & Microbiology, College of Medicine, University of Florida, Gainesville, FL, USA; Department of Neurology, University of Florida, Gainesville, FL, USA; Genetics Institute, University of Florida, Gainesville, FL, USA; McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
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19
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Kong HE, Zhao J, Xu S, Jin P, Jin Y. Fragile X-Associated Tremor/Ataxia Syndrome: From Molecular Pathogenesis to Development of Therapeutics. Front Cell Neurosci 2017; 11:128. [PMID: 28529475 PMCID: PMC5418347 DOI: 10.3389/fncel.2017.00128] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/18/2017] [Indexed: 12/31/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a premutation CGG repeat expansion (55-200 repeats) within the 5' UTR of the fragile X gene (FMR1). FXTAS is characterized by intension tremor, cerebellar ataxia, progressive neurodegeneration, parkinsonism and cognitive decline. The development of transgenic mouse and Drosophila melanogaster models carrying an expanded CGG repeat has yielded valuable insight into the pathophysiology of FXTAS. To date, we know of two main molecular mechanisms of this disorder: (1) a toxic gain of function of the expanded CGG-repeat FMR1 mRNA, which results in the binding/sequestration of the CGG-binding proteins; and (2) CGG repeat-associated non-AUG-initiated (RAN) translation, which generates a polyglycine peptide toxic to cells. Besides these CGG-mediated mechanisms, recent studies have shed light on additional mechanisms of pathogenesis, such as the antisense transcript ASFMR1, mitochondrial dysfunction, DNA damage from R-loop formation and 5-hydroxymethylcytosine (5hmC)-mediated epigenetic modulation. Here we summarize the recent progress towards understanding the etiology of FXTAS and provide an overview of potential treatment strategies.
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Affiliation(s)
- Ha Eun Kong
- Department of Human Genetics, School of Medicine, Emory UniversityAtlanta, GA, USA
| | - Juan Zhao
- The State Key Laboratory of Medical Genetics, School of Life Sciences, Central South UniversityChangsha, China
| | - Shunliang Xu
- Department of Neurology, 2nd Hospital of Shandong UniversityJinan, China
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory UniversityAtlanta, GA, USA
| | - Yan Jin
- Department of Ophthalmology, Second Hospital, Jilin UniversityChangchun, China
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20
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Sellier C, Buijsen RAM, He F, Natla S, Jung L, Tropel P, Gaucherot A, Jacobs H, Meziane H, Vincent A, Champy MF, Sorg T, Pavlovic G, Wattenhofer-Donze M, Birling MC, Oulad-Abdelghani M, Eberling P, Ruffenach F, Joint M, Anheim M, Martinez-Cerdeno V, Tassone F, Willemsen R, Hukema RK, Viville S, Martinat C, Todd PK, Charlet-Berguerand N. Translation of Expanded CGG Repeats into FMRpolyG Is Pathogenic and May Contribute to Fragile X Tremor Ataxia Syndrome. Neuron 2017; 93:331-347. [PMID: 28065649 PMCID: PMC5263258 DOI: 10.1016/j.neuron.2016.12.016] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/06/2016] [Accepted: 12/02/2016] [Indexed: 11/26/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a limited expansion of CGG repeats in the 5′ UTR of FMR1. Two mechanisms are proposed to cause FXTAS: RNA gain-of-function, where CGG RNA sequesters specific proteins, and translation of CGG repeats into a polyglycine-containing protein, FMRpolyG. Here we developed transgenic mice expressing CGG repeat RNA with or without FMRpolyG. Expression of FMRpolyG is pathogenic, while the sole expression of CGG RNA is not. FMRpolyG interacts with the nuclear lamina protein LAP2β and disorganizes the nuclear lamina architecture in neurons differentiated from FXTAS iPS cells. Finally, expression of LAP2β rescues neuronal death induced by FMRpolyG. Overall, these results suggest that translation of expanded CGG repeats into FMRpolyG alters nuclear lamina architecture and drives pathogenesis in FXTAS. CGG repeats in the 5′ UTR of FMR1 are translated through initiation to an ACG codon Translation of CGG repeats in the polyglycine protein, FMRpolyG, is toxic in mice FMRpolyG binds and disrupts protein of the nuclear lamina
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Affiliation(s)
- Chantal Sellier
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France.
| | - Ronald A M Buijsen
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Fang He
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran Association Health System, Ann Arbor, MI 48105, USA; Department of Biological and Health Sciences, Texas A&M University - Kingsville, Kingsville, TX 78363, USA
| | - Sam Natla
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Laura Jung
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Philippe Tropel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Angeline Gaucherot
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Hugues Jacobs
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Hamid Meziane
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Alexandre Vincent
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie-France Champy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Tania Sorg
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Guillaume Pavlovic
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie Wattenhofer-Donze
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Marie-Christine Birling
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; PHENOMIN, Institut Clinique de la Souris (ICS), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mustapha Oulad-Abdelghani
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Pascal Eberling
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Frank Ruffenach
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mathilde Joint
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France
| | - Mathieu Anheim
- Department of Neurology, University Hospital of Strasbourg, Hôpital de Hautepierre, 67200 Strasbourg, France
| | - Veronica Martinez-Cerdeno
- Department of Pathology and Laboratory Medicine, University of California, Davis, Sacramento, CA 95817, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA 95817, USA; M.I.N.D. Institute, University of California, Davis, Health System, Sacramento, CA 95817, USA
| | - Flora Tassone
- M.I.N.D. Institute, University of California, Davis, Health System, Sacramento, CA 95817, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Renate K Hukema
- Department of Clinical Genetics, Erasmus MC, 3015 Rotterdam, the Netherlands
| | - Stéphane Viville
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; Laboratoire de Diagnostic Génétique, UF3472 - Infertilité, Nouvel Hôpital Civil, 1 place de l'Hôpital, 67091 Strasbourg, France; IPPTS, 3 rue Koeberlé, 67000 Strasbourg, France
| | | | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA; Veteran Association Health System, Ann Arbor, MI 48105, USA
| | - Nicolas Charlet-Berguerand
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR7104, University of Strasbourg, 67400 Illkirch, France; Université de Strasbourg, 67000 Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, 67400 Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U964, 67400 Illkirch, France.
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21
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Andriani GA, Vijg J, Montagna C. Mechanisms and consequences of aneuploidy and chromosome instability in the aging brain. Mech Ageing Dev 2017; 161:19-36. [PMID: 27013377 PMCID: PMC5490080 DOI: 10.1016/j.mad.2016.03.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 03/17/2016] [Accepted: 03/19/2016] [Indexed: 01/31/2023]
Abstract
Aneuploidy and polyploidy are a form of Genomic Instability (GIN) known as Chromosomal Instability (CIN) characterized by sporadic abnormalities in chromosome copy numbers. Aneuploidy is commonly linked to pathological states. It is a hallmark of spontaneous abortions and birth defects and it is observed virtually in every human tumor, therefore being generally regarded as detrimental for the development or the maturation of tissues under physiological conditions. Polyploidy however, occurs as part of normal physiological processes during maturation and differentiation of some mammalian cell types. Surprisingly, high levels of aneuploidy are present in the brain, and their frequency increases with age suggesting that the brain is able to maintain its functionality in the presence of high levels of mosaic aneuploidy. Because somatic aneuploidy with age can reach exceptionally high levels, it is likely to have long-term adverse effects in this organ. We describe the mechanisms accountable for an abnormal DNA content with a particular emphasis on the CNS where cell division is limited. Next, we briefly summarize the types of GIN known to date and discuss how they interconnect with CIN. Lastly we highlight how several forms of CIN may contribute to genetic variation, tissue degeneration and disease in the CNS.
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Affiliation(s)
- Grasiella A Andriani
- Department of Genetics, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Jan Vijg
- Department of Genetics, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA; Department Ophthalmology and Visual Science, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA; Department of Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA
| | - Cristina Montagna
- Department of Genetics, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA; Department of Pathology, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY 10461, USA.
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22
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Brain structure and intragenic DNA methylation are correlated, and predict executive dysfunction in fragile X premutation females. Transl Psychiatry 2016; 6:e984. [PMID: 27959330 PMCID: PMC5290342 DOI: 10.1038/tp.2016.250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 09/28/2016] [Indexed: 02/07/2023] Open
Abstract
DNA methylation of the Fragile X mental retardation 1 (FMR1) exon 1/intron 1 boundary has been associated with executive dysfunction in female carriers of a FMR1 premutation (PM: 55-199 CGG repeats), whereas neuroanatomical changes have been associated with executive dysfunction in PM males. To our knowledge, this study for the first time examined the inter-relationships between executive function, neuroanatomical structure and molecular measures (DNA methylation and FMR1 mRNA levels in blood) in PM and control (<44 CGG repeats) females. In the PM group, FMR1 intron 1 methylation was positively associated with executive function and cortical thickness in middle and superior frontal gyri, and left inferior parietal gyrus. By contrast, in the control group, FMR1 intron 1 methylation was negatively associated with cortical thickness of the left middle frontal gyrus and superior frontal gyri. No significant associations were revealed for either group between FMR1 mRNA and neuroanatomical structure or executive function. In the PM group, the lack of any significant association between FMR1 mRNA levels and phenotypic measures found in this study suggests that either FMR1 expression is not well conserved between tissues, or that FMR1 intron 1 methylation is linked to neuroanatomical and cognitive phenotype in PM females via a different mechanism.
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Molecular Inconsistencies in a Fragile X Male with Early Onset Ataxia. Genes (Basel) 2016; 7:genes7090068. [PMID: 27657133 PMCID: PMC5042398 DOI: 10.3390/genes7090068] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 08/22/2016] [Accepted: 09/13/2016] [Indexed: 12/20/2022] Open
Abstract
Mosaicism for FMR1 premutation (PM: 55–199 CGG)/full mutation (FM: >200 CGG) alleles or the presence of unmethylated FM (UFM) have been associated with a less severe fragile X syndrome (FXS) phenotype and fragile X associated tremor/ataxia syndrome (FXTAS)—a late onset neurodegenerative disorder. We describe a 38 year old male carrying a 100% methylated FM detected with Southern blot (SB), which is consistent with complete silencing of FMR1 and a diagnosis of fragile X syndrome. However, his formal cognitive scores were not at the most severe end of the FXS phenotype and he displayed tremor and ataxic gait. With the association of UFM with FXTAS, we speculated that his ataxia might be related to an undetected proportion of UFM alleles. Such UFM alleles were confirmed by more sensitive PCR based methylation testing showing FM methylation between 60% and 70% in blood, buccal, and saliva samples and real-time PCR analysis showing incomplete silencing of FMR1. While he did not meet diagnostic criteria for FXTAS based on MRI findings, the underlying cause of his ataxia may be related to UFM alleles not detected by SB, and follow-up clinical and molecular assessment are justified if his symptoms worsen.
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24
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Alaqeel AM, Abou Al-Shaar H, Shariff RK, Albakr A. The role of RNA metabolism in neurological diseases. Balkan J Med Genet 2016; 18:5-14. [PMID: 27785391 PMCID: PMC5026263 DOI: 10.1515/bjmg-2015-0080] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Neurodegenerative disorders are commonly encountered in medical practices. Such diseases can lead to major morbidity and mortality among the affected individuals. The molecular pathogenesis of these disorders is not yet clear. Recent literature has revealed that mutations in RNA-binding proteins are a key cause of several human neuronal-based diseases. This review discusses the role of RNA metabolism in neurological diseases with specific emphasis on roles of RNA translation and microRNAs in neurodegeneration, RNA-mediated toxicity, repeat expansion diseases and RNA metabolism, molecular pathogenesis of amyotrophic lateral sclerosis and frontotemporal dementia, and neurobiology of survival motor neuron (SMN) and spinal muscular atrophy.
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Affiliation(s)
- A M Alaqeel
- Department of Neurosurgery, University of Calgary, Calgary, Alberta, Canada; Division of Neurosurgery, Department of Surgery, King Saud University, Riyadh, Saudi Arabia
| | - H Abou Al-Shaar
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - R K Shariff
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - A Albakr
- Division of Neurosurgery, Department of Surgery, King Saud University, Riyadh, Saudi Arabia
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25
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Napoli E, Song G, Schneider A, Hagerman R, Eldeeb MAAA, Azarang A, Tassone F, Giulivi C. Warburg effect linked to cognitive-executive deficits in FMR1 premutation. FASEB J 2016; 30:3334-3351. [PMID: 27335370 DOI: 10.1096/fj.201600315r] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 06/14/2016] [Indexed: 11/11/2022]
Abstract
A 55-200 CGG repeat expansion in the 5'-UTR of the fragile X mental retardation 1 (FMR1) gene is known as a premutation. Some carriers are affected by the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS), primary ovarian insufficiency, and neurobehavioral impairments. Based on the mitochondrial dysfunction observed in fibroblasts and brain samples from carriers, as well as in neurons and brains from a mouse model of the premutation, we evaluated the presence of the Warburg effect in peripheral blood mononuclear cells (PBMCs) from 30 premutation carriers with either a rebalance of the metabolism [increasing glycolysis while decreasing oxidative phosphorylation (oxphos)] or a metabolic amplification (increasing glycolysis while maintaining/increasing oxphos). Deficits in oxphos-more pronounced in FXTAS-affected subjects-were accompanied by a shift toward glycolysis, suggesting increased glycolysis despite aerobic conditions. Differential proteomics extended these findings, unveiling a decreased antioxidant response, translation, and disrupted extracellular matrix and cytoskeleton organization with activation of prosenescence pathways. Lower bioenergetics segregated with increased incidence of low executive function, tremors, below-average IQ, and FXTAS. The combination of functional and proteomic data unveiled new mechanisms related to energy production in the premutation, showing the potential of being applicable to other psychiatric disorders to identify endophenotype-specific responses relevant to neurobiology.-Napoli, E., Song, G., Schneider, A., Hagerman, R., Eldeeb, M. A. A. A., Azarang, A., Tassone, F., Giulivi, C. Warburg effect linked to cognitive-executive deficits in FMR1 premutation.
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Affiliation(s)
- Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California, USA
| | - Gyu Song
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California, USA
| | - Andrea Schneider
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Davis, California, USA; Department of Pediatrics, University of California Davis Medical Center, Sacramento California, USA; and
| | - Randi Hagerman
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Davis, California, USA; Department of Pediatrics, University of California Davis Medical Center, Sacramento California, USA; and
| | - Marwa Abd Al Azaim Eldeeb
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Davis, California, USA
| | - Atoosa Azarang
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Davis, California, USA
| | - Flora Tassone
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California, Davis, Davis, California, USA; Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, California, USA
| | - Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California, USA; Department of Pediatrics, University of California Davis Medical Center, Sacramento California, USA; and
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26
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Pham TT, Yin J, Eid JS, Adams E, Lam R, Turner SW, Loomis EW, Wang JY, Hagerman PJ, Hanes JW. Single-locus enrichment without amplification for sequencing and direct detection of epigenetic modifications. Mol Genet Genomics 2016; 291:1491-504. [PMID: 26825750 DOI: 10.1007/s00438-016-1167-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 01/06/2016] [Indexed: 12/16/2022]
Abstract
A gene-level targeted enrichment method for direct detection of epigenetic modifications is described. The approach is demonstrated on the CGG-repeat region of the FMR1 gene, for which large repeat expansions, hitherto refractory to sequencing, are known to cause fragile X syndrome. In addition to achieving a single-locus enrichment of nearly 700,000-fold, the elimination of all amplification steps removes PCR-induced bias in the repeat count and preserves the native epigenetic modifications of the DNA. In conjunction with the single-molecule real-time sequencing approach, this enrichment method enables direct readout of the methylation status and the CGG repeat number of the FMR1 allele(s) for a clonally derived cell line. The current method avoids potential biases introduced through chemical modification and/or amplification methods for indirect detection of CpG methylation events.
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Affiliation(s)
| | - Jun Yin
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, 95616, USA.,Dendrite Morphogenesis and Plasticity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, 20892, USA
| | - John S Eid
- Pacific Biosciences, Menlo Park, CA, 94025, USA.,Whole Biome, Inc., San Francisco, CA, 94107, USA
| | - Evan Adams
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, 95616, USA
| | - Regina Lam
- Pacific Biosciences, Menlo Park, CA, 94025, USA
| | | | - Erick W Loomis
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, 95616, USA.,Faculty of Medicine, Department of Surgery & Cancer, Institute of Reproductive and Developmental Biology, Hammersmith Campus Imperial College London, London, UK
| | - Jun Yi Wang
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, 95616, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA, 95616, USA
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27
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Oh SY, He F, Krans A, Frazer M, Taylor JP, Paulson HL, Todd PK. RAN translation at CGG repeats induces ubiquitin proteasome system impairment in models of fragile X-associated tremor ataxia syndrome. Hum Mol Genet 2015; 24:4317-26. [PMID: 25954027 PMCID: PMC4492395 DOI: 10.1093/hmg/ddv165] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 03/30/2015] [Accepted: 05/04/2015] [Indexed: 12/11/2022] Open
Abstract
Fragile X-associated tremor ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a CGG trinucleotide repeat expansion in the 5' UTR of the Fragile X gene, FMR1. FXTAS is thought to arise primarily from an RNA gain-of-function toxicity mechanism. However, recent studies demonstrate that the repeat also elicits production of a toxic polyglycine protein, FMRpolyG, via repeat-associated non-AUG (RAN)-initiated translation. Pathologically, FXTAS is characterized by ubiquitin-positive intranuclear neuronal inclusions, raising the possibility that failure of protein quality control pathways could contribute to disease pathogenesis. To test this hypothesis, we used Drosophila- and cell-based models of CGG-repeat-associated toxicity. In Drosophila, ubiquitin proteasome system (UPS) impairment led to enhancement of CGG-repeat-induced degeneration, whereas overexpression of the chaperone protein HSP70 suppressed this toxicity. In transfected mammalian cells, CGG repeat expression triggered accumulation of a UPS reporter in a length-dependent fashion. To delineate the contributions from CGG repeats as RNA from RAN translation-associated toxicity, we enhanced or impaired the production of FMRpolyG in these models. Driving expression of FMRpolyG enhanced induction of UPS impairment in cell models, while prevention of RAN translation attenuated UPS impairment in cells and suppressed the genetic interaction with UPS manipulation in Drosophila. Taken together, these findings suggest that CGG repeats induce UPS impairment at least in part through activation of RAN translation.
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Affiliation(s)
- Seok Yoon Oh
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Fang He
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Michelle Frazer
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, TN, USA and
| | - Henry L Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA, Neurology, U.S. Department of Veterans Affairs Medical Center, Ann Arbor, MI, USA
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28
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Lorefice L, Tranquilli S, Fenu G, Murru MR, Frau J, Rolesu M, Coghe GC, Marrosu F, Marrosu MG, Cocco E. A genetic study of the FMR1 gene in a Sardinian multiple sclerosis population. Neurol Sci 2015; 36:2213-20. [PMID: 26194536 DOI: 10.1007/s10072-015-2339-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 07/13/2015] [Indexed: 02/04/2023]
Abstract
Multiple sclerosis (MS) is a complex autoimmune disease originated from the interplay between genetic and environmental factors. An overlap of clinical and neuroradiological parameters has been described between MS and an adult-onset neurodegenerative disorder, the fragile-X-associated tremor/ataxia syndrome (FXTAS). This syndrome is caused by a trinucleotide premutation expansion of a CGG sequence in the 55-200 repeat range, which is located in the fragile-X mental retardation 1 (FMR1) gene. Female premutation carriers have an increased propensity for immune-mediated disorders. Recently, a case of co-occurrence of MS and FXTAS was reported. Assuming that the premutation expansion may play a role in the MS susceptibility, we evaluated its frequency in a cohort of MS patients from Sardinia, an island characterized by a very high frequency of MS. Nuclear DNA was extracted by standard methods, purified with bisulfite treatment and then amplified twice by PCR with specific primers. Microsatellite analysis was performed and emizogotic subjects were sequenced. Clinical data of patients were also collected. Only 1/755 MS patients exhibited the premutation expansion with a heterozygosis pattern (30/58). No pathogenic repeat expansions (>200 repeats) were found in the entire cohort. Repeats labeled as the gray zone (45-60 repeats) were observed in 15/755 patients. No specific clinical features concerning disease course, disease activity, and disability were reported for these patients. Our results do not support a possible role for premutation or gray zone alleles in MS Sardinian patients. Further studies are needed to better understand the relationship between FXTAS and MS.
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Affiliation(s)
- L Lorefice
- Department of Public Health and Clinical and Molecular Medicine, Multiple Sclerosis Center, University of Cagliari, Ospedale "Binaghi", via Is Guadazzonis, 2, 09126, Cagliari, Italy.
| | - S Tranquilli
- Department of Medical Sciences, Institute of Neurology, University of Cagliari, Cagliari, Italy
| | - G Fenu
- Department of Public Health and Clinical and Molecular Medicine, Multiple Sclerosis Center, University of Cagliari, Ospedale "Binaghi", via Is Guadazzonis, 2, 09126, Cagliari, Italy
| | - M R Murru
- ASL8-Department of Medical Sciences, Multiple Sclerosis Center, University of Cagliari, Cagliari, Italy
| | - J Frau
- Department of Public Health and Clinical and Molecular Medicine, Multiple Sclerosis Center, University of Cagliari, Ospedale "Binaghi", via Is Guadazzonis, 2, 09126, Cagliari, Italy
| | - M Rolesu
- ASL8-Department of Medical Sciences, Multiple Sclerosis Center, University of Cagliari, Cagliari, Italy
| | - G C Coghe
- Department of Public Health and Clinical and Molecular Medicine, Multiple Sclerosis Center, University of Cagliari, Ospedale "Binaghi", via Is Guadazzonis, 2, 09126, Cagliari, Italy
| | - F Marrosu
- Department of Medical Sciences, Institute of Neurology, University of Cagliari, Cagliari, Italy
| | - M G Marrosu
- Department of Medical Sciences, Multiple Sclerosis Center, University of Cagliari, Cagliari, Italy
| | - E Cocco
- Department of Public Health and Clinical and Molecular Medicine, Multiple Sclerosis Center, University of Cagliari, Ospedale "Binaghi", via Is Guadazzonis, 2, 09126, Cagliari, Italy
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29
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Abstract
RNAs adopt diverse folded structures that are essential for function and thus play critical roles in cellular biology. A striking example of this is the ribosome, a complex, three-dimensionally folded macromolecular machine that orchestrates protein synthesis. Advances in RNA biochemistry, structural and molecular biology, and bioinformatics have revealed other non-coding RNAs whose functions are dictated by their structure. It is not surprising that aberrantly folded RNA structures contribute to disease. In this Review, we provide a brief introduction into RNA structural biology and then describe how RNA structures function in cells and cause or contribute to neurological disease. Finally, we highlight successful applications of rational design principles to provide chemical probes and lead compounds targeting structured RNAs. Based on several examples of well-characterized RNA-driven neurological disorders, we demonstrate how designed small molecules can facilitate the study of RNA dysfunction, elucidating previously unknown roles for RNA in disease, and provide lead therapeutics.
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Affiliation(s)
- Viachaslau Bernat
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA
| | - Matthew D Disney
- Department of Chemistry, The Scripps Research Institute, 130 Scripps Way, Jupiter, FL 33458, USA.
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30
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Shelton AL, Cornish KM, Godler DE, Clough M, Kraan C, Bui M, Fielding J. Delineation of the working memory profile in female FMR1 premutation carriers: the effect of cognitive load on ocular motor responses. Behav Brain Res 2015; 282:194-200. [PMID: 25591477 DOI: 10.1016/j.bbr.2015.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/17/2014] [Accepted: 01/06/2015] [Indexed: 01/10/2023]
Abstract
Fragile X mental retardation 1 (FMR1) premutation carriers (PM-carriers) are characterised as having mid-sized expansions of between 55 and 200 CGG repeats in the 5' untranslated region of the FMR1 gene. While there is evidence of executive dysfunction in PM-carriers, few studies have explicitly explored working memory capabilities in female PM-carriers. 14 female PM-carriers and 13 age- and IQ-matched healthy controls completed an ocular motor n-back working memory paradigm. This task examined working memory ability and the effect of measured increases in cognitive load. Female PM-carriers were found to have attenuated working memory capabilities. Increasing the cognitive load did not elicit the expected reciprocal increase in the task errors for female PM-carriers, as it did in controls. However female PM-carriers took longer to respond than controls, regardless of the cognitive load. Further, FMR1 mRNA levels were found to significantly predict PM-carrier response time. Although preliminary, these findings provide further evidence of executive dysfunction, specifically disruption to working memory processes, which were found to be associated with increases in FMR1 mRNA expression in female PM-carriers. With future validation, ocular motor paradigms such as the n-back paradigm will be critical to the development of behavioural biomarkers for identification of PM-carrier cognitive-affective phenotypes.
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Affiliation(s)
- Annie L Shelton
- School of Psychological Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Kim M Cornish
- School of Psychological Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - David E Godler
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne 3052, VIC, Australia
| | - Meaghan Clough
- School of Psychological Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Claudine Kraan
- School of Psychological Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia
| | - Minh Bui
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne 3010, VIC, Australia
| | - Joanne Fielding
- School of Psychological Science, Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, VIC, Australia.
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31
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Duan R, Sharma S, Xia Q, Garber K, Jin P. Towards Understanding RNA-Mediated Neurological Disorders. J Genet Genomics 2014; 41:473-84. [DOI: 10.1016/j.jgg.2014.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 08/10/2014] [Accepted: 08/12/2014] [Indexed: 12/14/2022]
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32
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Sellier C, Usdin K, Pastori C, Peschansky VJ, Tassone F, Charlet-Berguerand N. The multiple molecular facets of fragile X-associated tremor/ataxia syndrome. J Neurodev Disord 2014; 6:23. [PMID: 25161746 PMCID: PMC4144988 DOI: 10.1186/1866-1955-6-23] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 11/15/2013] [Indexed: 02/03/2023] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset inherited neurodegenerative disorder characterized by intentional tremor, gait ataxia, autonomic dysfunction, and cognitive decline. FXTAS is caused by the presence of a long CGG repeat tract in the 5′ UTR of the FMR1 gene. In contrast to Fragile X syndrome, in which the FMR1 gene harbors over 200 CGG repeats but is transcriptionally silent, the clinical features of FXTAS arise from a toxic gain of function of the elevated levels of FMR1 transcript containing the long CGG tract. However, how this RNA leads to neuronal cell dysfunction is unknown. Here, we discuss the latest advances in the current understanding of the possible molecular basis of FXTAS.
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Affiliation(s)
- Chantal Sellier
- Department of Translational Medicine, IGBMC, INSERM U964 Illkirch, France
| | - Karen Usdin
- Section on Gene Structure and Disease, NIDDK, National Institutes of Health, Bethesda MD 20892, USA
| | - Chiara Pastori
- Department of Psychiatry and Behavioral Sciences and Center for Therapeutic Innovation, Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami FL 33136, USA
| | - Veronica J Peschansky
- Department of Psychiatry and Behavioral Sciences and Center for Therapeutic Innovation, Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami FL 33136, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Sacramento CA 95817, USA ; MIND Institute, University of California Davis Medical Center, Sacramento CA 95817, USA
| | - Nicolas Charlet-Berguerand
- Department of Translational Medicine, IGBMC, INSERM U964 Illkirch, France ; Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS UMR7104, INSERM U964, University of Strasbourg, 1 rue Laurent Fries, Illkirch F-67404, France
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33
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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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Galloway JN, Shaw C, Yu P, Parghi D, Poidevin M, Jin P, Nelson DL. CGG repeats in RNA modulate expression of TDP-43 in mouse and fly models of fragile X tremor ataxia syndrome. Hum Mol Genet 2014; 23:5906-15. [PMID: 24986919 DOI: 10.1093/hmg/ddu314] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Determining the molecular mechanism(s) leading to Purkinje neuron loss in the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS) is limited by the complex morphology of this cell type. Purkinje neurons are notoriously difficult to isolate and maintain in culture presenting considerable difficultly to identify molecular changes in response to expanded CGG repeat (rCGG)-containing mRNA that induces neurotoxicity in FXTAS. Several studies have uncovered a number of RNA-binding proteins involved in translation that aberrantly interact with the CGG-containing RNA; however, whether these interactions alter the translational profile of cells has not been investigated. Here we employ bacTRAP translational profiling to demonstrate that Purkinje neurons ectopically expressing 90 CGG repeats exhibit a dramatic change in their translational profile even prior to the onset of rCGG-induced phenotypes. This approach identified ∼500 transcripts that are differentially associated with ribosomes in r(CGG)₉₀-expressing mice. Functional annotation cluster analysis revealed broad ontologies enriched in the r(CGG)₉₀ list, including RNA binding and response to stress. Intriguingly, a transcript for the Tardbp gene, implicated in a number of other neurodegenerative disorders, exhibits altered association with ribosomes in the presence of r(CGG)₉₀ repeats. We therefore tested and showed that reduced association of Tardbp mRNA with the ribosomes results in a loss of TDP-43 protein expression in r(CGG)₉₀-expressing Purkinje neurons. Furthermore, we showed that TDP-43 could modulate the rCGG repeat-mediated toxicity in a Drosophila model that we developed previously. These findings together suggest that translational dysregulation may be an underlying mechanism of rCGG-induced neurotoxicity in FXTAS.
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Affiliation(s)
| | - Chad Shaw
- Department of Human and Molecular Genetics and
| | - Peng Yu
- Department of Human and Molecular Genetics and
| | - Deena Parghi
- Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA and
| | - Mickael Poidevin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David L Nelson
- Interdepartmental Program in Cell and Molecular Biology, Department of Human and Molecular Genetics and
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Juang BT, Ludwig AL, Benedetti KL, Gu C, Collins K, Morales C, Asundi A, Wittmann T, L'Etoile N, Hagerman PJ. Expression of an expanded CGG-repeat RNA in a single pair of primary sensory neurons impairs olfactory adaptation in Caenorhabditis elegans. Hum Mol Genet 2014; 23:4945-59. [PMID: 24821701 PMCID: PMC4140470 DOI: 10.1093/hmg/ddu210] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a severe neurodegenerative disorder that affects carriers of premutation CGG-repeat expansion alleles of the fragile X mental retardation 1 (FMR1) gene; current evidence supports a causal role of the expanded CGG repeat within the FMR1 mRNA in the pathogenesis of FXTAS. Though the mRNA has been observed to induce cellular toxicity in FXTAS, the mechanisms are unclear. One common neurophysiological characteristic of FXTAS patients is their inability to properly attenuate their response to an auditory stimulus upon receipt of a small pre-stimulus. Therefore, to gain genetic and cell biological insight into FXTAS, we examined the effect of expanded CGG repeats on the plasticity of the olfactory response of the genetically tractable nematode, Caenorhabditis elegans (C. elegans). While C. elegans is innately attracted to odors, this response can be downregulated if the odor is paired with starvation. We found that expressing expanded CGG repeats in olfactory neurons interfered with this plasticity without affecting either the innate odor-seeking response or the olfactory neuronal morphology. Interrogation of three RNA regulatory pathways indicated that the expanded CGG repeats act via the C. elegans microRNA (miRNA)-specific Argonaute ALG-2 to diminish olfactory plasticity. This observation suggests that the miRNA-Argonaute pathway may play a pathogenic role in subverting neuronal function in FXTAS.
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Affiliation(s)
- Bi-Tzen Juang
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Anna L Ludwig
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA 95616, USA
| | - Kelli L Benedetti
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Chen Gu
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Kimberly Collins
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Christopher Morales
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Aarati Asundi
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Torsten Wittmann
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Noelle L'Etoile
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, CA 95616, USA, MIND Institute, University of California, Davis, Health System, Sacramento, CA 95817, USA
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36
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Mohan A, Goodwin M, Swanson MS. RNA-protein interactions in unstable microsatellite diseases. Brain Res 2014; 1584:3-14. [PMID: 24709120 DOI: 10.1016/j.brainres.2014.03.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/25/2014] [Accepted: 03/26/2014] [Indexed: 12/14/2022]
Abstract
A novel RNA-mediated disease mechanism has emerged from studies on dominantly inherited neurological disorders caused by unstable microsatellite expansions in non-coding regions of the genome. These non-coding tandem repeat expansions trigger the production of unusual RNAs that gain a toxic function, which involves the formation of RNA repeat structures that interact with, and alter the activities of, various factors required for normal RNA processing as well as additional cellular functions. In this review, we explore the deleterious effects of toxic RNA expression and discuss the various model systems currently available for studying RNA gain-of-function in neurologic diseases. Common themes, including bidirectional transcription and repeat-associated non-ATG (RAN) translation, have recently emerged from expansion disease studies. These and other discoveries have highlighted the need for further investigations designed to provide the additional mechanistic insights essential for future therapeutic development.
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Affiliation(s)
- Apoorva Mohan
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA
| | - Marianne Goodwin
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics and Microbiology, Center for NeuroGenetics and the Genetics Institute, University of Florida, College of Medicine, Cancer Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610-3610, USA.
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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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Mateu-Huertas E, Rodriguez-Revenga L, Alvarez-Mora MI, Madrigal I, Willemsen R, Milà M, Martí E, Estivill X. Blood expression profiles of fragile X premutation carriers identify candidate genes involved in neurodegenerative and infertility phenotypes. Neurobiol Dis 2014; 65:43-54. [PMID: 24418349 DOI: 10.1016/j.nbd.2013.12.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 12/16/2013] [Accepted: 12/30/2013] [Indexed: 12/29/2022] Open
Abstract
Male premutation carriers presenting between 55 and 200 CGG repeats in the Fragile-X-associated (FMR1) gene are at risk of developing Fragile X Tremor/Ataxia Syndrome (FXTAS), and females undergo Premature Ovarian Failure (POF1). Here, we have evaluated gene expression profiles from blood in male FMR1 premutation carriers and detected a strong deregulation of genes enriched in FXTAS relevant biological pathways, including inflammation, neuronal homeostasis and viability. Gene expression profiling distinguished between control individuals, carriers with FXTAS and carriers without FXTAS, with levels of expanded FMR1 mRNA being increased in FXTAS patients. In vitro studies in a neuronal cell model indicate that expression levels of expanded FMR1 5'-UTR are relevant in modulating the transcriptome. Thus, perturbations of the transcriptome may be an interplay between the CGG expansion size and FMR1 expression levels. Several deregulated genes (DFFA, BCL2L11, BCL2L1, APP, SOD1, RNF10, HDAC5, KCNC3, ATXN7, ATXN3 and EAP1) were validated in brain samples of a FXTAS mouse model. Downregulation of EAP1, a gene involved in the female reproductive system physiology, was confirmed in female carriers. Decreased levels were detected in female carriers with POF1 compared to those without POF1, suggesting that EAP1 levels contribute to ovarian insufficiency. In summary, gene expression profiling in blood has uncovered mechanisms that may underlie different pathological aspects of the premutation. A better understanding of the transcriptome dynamics in relation with expanded FMR1 mRNA expression levels and CGG expansion size may provide mechanistic insights into the disease process and a more accurate FXTAS diagnosis to the myriad of phenotypes associated with the premutation.
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Affiliation(s)
- Elisabet Mateu-Huertas
- Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona 08003, Catalonia, Spain; Universitat Pompeu Fabra (UPF), Barcelona 08003, Catalonia, Spain; Hospital del Mar Medical Research Institute (IMIM), Barcelona 08003, Catalonia, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), CRG, Barcelona 08003, Catalonia, Spain
| | - Laia Rodriguez-Revenga
- Biochemistry and Molecular Genetics Department, Hospital Clínic and IDIBAPS, Barcelona 08036, Catalonia, Spain; CIBER de Enfermedades Raras (CIBERER), Hospital Clínic, Barcelona 08003, Catalonia, Spain
| | - Maria Isabel Alvarez-Mora
- Biochemistry and Molecular Genetics Department, Hospital Clínic and IDIBAPS, Barcelona 08036, Catalonia, Spain; CIBER de Enfermedades Raras (CIBERER), Hospital Clínic, Barcelona 08003, Catalonia, Spain
| | - Irene Madrigal
- Biochemistry and Molecular Genetics Department, Hospital Clínic and IDIBAPS, Barcelona 08036, Catalonia, Spain; CIBER de Enfermedades Raras (CIBERER), Hospital Clínic, Barcelona 08003, Catalonia, Spain
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam 3000 DR, The Netherlands
| | - Montserrat Milà
- Biochemistry and Molecular Genetics Department, Hospital Clínic and IDIBAPS, Barcelona 08036, Catalonia, Spain; CIBER de Enfermedades Raras (CIBERER), Hospital Clínic, Barcelona 08003, Catalonia, Spain
| | - Eulàlia Martí
- Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona 08003, Catalonia, Spain; Universitat Pompeu Fabra (UPF), Barcelona 08003, Catalonia, Spain; Hospital del Mar Medical Research Institute (IMIM), Barcelona 08003, Catalonia, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), CRG, Barcelona 08003, Catalonia, Spain.
| | - Xavier Estivill
- Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona 08003, Catalonia, Spain; Universitat Pompeu Fabra (UPF), Barcelona 08003, Catalonia, Spain; Hospital del Mar Medical Research Institute (IMIM), Barcelona 08003, Catalonia, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), CRG, Barcelona 08003, Catalonia, Spain.
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Oldenburg AR, Delbarre E, Thiede B, Vigouroux C, Collas P. Deregulation of Fragile X-related protein 1 by the lipodystrophic lamin A p.R482W mutation elicits a myogenic gene expression program in preadipocytes. Hum Mol Genet 2013; 23:1151-62. [PMID: 24108105 DOI: 10.1093/hmg/ddt509] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The nuclear lamina is implicated in the regulation of various nuclear functions. Several laminopathy-causing mutations in the LMNA gene, notably the p.R482W substitution linked to familial partial lipodystrophy type 2 (FPLD2), are clustered in the immunoglobulin fold of lamin A. We report a functional association between lamin A and fragile X-related protein 1 (FXR1P), a protein of the fragile X-related family involved in fragile X syndrome. Searching for proteins differentially interacting with the immunoglobulin fold of wild-type and R482W mutant lamin A, we identify FXR1P as a novel component of the lamin A protein network. The p.R482W mutation abrogates interaction of FXR1P with lamin A. Fibroblasts from FPLD2 patients display elevated levels of FXR1P and delocalized FXR1P. In human adipocyte progenitors, deregulation of lamin A expression leads to FXR1P up-regulation, impairment of adipogenic differentiation and induction of myogenin expression. FXR1P overexpression also stimulates a myogenic gene expression program in these cells. Our results demonstrate a cross-talk between proteins hitherto implicated in two distinct mesodermal pathologies. We propose a model where the FPLD2 lamin A p.R482W mutation elicits, through up-regulation of FXR1P, a remodeling of an adipogenic differentiation program into a myogenic program.
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Affiliation(s)
- Anja R Oldenburg
- Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences and Norwegian Center for Stem Cell Research, Faculty of Medicine, University of Oslo, PO Box 1112, Blindern, Oslo 0317, Norway
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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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Todd PK, Oh SY, Krans A, He F, Sellier C, Frazer M, Renoux AJ, Chen KC, Scaglione KM, Basrur V, Elenitoba-Johnson K, Vonsattel JP, Louis ED, Sutton MA, Taylor JP, Mills RE, Charlet-Berguerand N, Paulson HL. CGG repeat-associated translation mediates neurodegeneration in fragile X tremor ataxia syndrome. Neuron 2013; 78:440-55. [PMID: 23602499 DOI: 10.1016/j.neuron.2013.03.026] [Citation(s) in RCA: 350] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2013] [Indexed: 01/18/2023]
Abstract
Fragile X-associated tremor ataxia syndrome (FXTAS) results from a CGG repeat expansion in the 5' UTR of FMR1. This repeat is thought to elicit toxicity as RNA, yet disease brains contain ubiquitin-positive neuronal inclusions, a pathologic hallmark of protein-mediated neurodegeneration. We explain this paradox by demonstrating that CGG repeats trigger repeat-associated non-AUG-initiated (RAN) translation of a cryptic polyglycine-containing protein, FMRpolyG. FMRpolyG accumulates in ubiquitin-positive inclusions in Drosophila, cell culture, mouse disease models, and FXTAS patient brains. CGG RAN translation occurs in at least two of three possible reading frames at repeat sizes ranging from normal (25) to pathogenic (90), but inclusion formation only occurs with expanded repeats. In Drosophila, CGG repeat toxicity is suppressed by eliminating RAN translation and enhanced by increased polyglycine protein production. These studies expand the growing list of nucleotide repeat disorders in which RAN translation occurs and provide evidence that RAN translation contributes to neurodegeneration.
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Affiliation(s)
- Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA.
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Cao Z, Hulsizer S, Cui Y, Pretto DL, Kim KH, Hagerman PJ, Tassone F, Pessah IN. Enhanced asynchronous Ca(2+) oscillations associated with impaired glutamate transport in cortical astrocytes expressing Fmr1 gene premutation expansion. J Biol Chem 2013; 288:13831-41. [PMID: 23553633 DOI: 10.1074/jbc.m112.441055] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND FMR1 CGG expansion repeats in the premutation range have not been linked to astrocyte pathophysiology. RESULTS Premutation cortical astrocytes display decreased Glu transporter expression/activity and enhanced asynchronous Ca(2+) oscillations. CONCLUSION Glu transport and Ca(2+) signaling defects in premutation astrocytes could contribute to FXTAS neuropathology. SIGNIFICANCE Premutation astrocytes may have an etiological role in FXTAS neuropathology. Premutation CGG repeat expansions (55-200 CGG repeats; preCGG) within the fragile X mental retardation 1 (FMR1) gene can cause fragile X-associated tremor/ataxia syndrome. Defects in early neuronal migration and morphology, electrophysiological activity, and mitochondria trafficking have been described in a premutation mouse model, but whether preCGG mutations also affect astrocyte function remains unknown. PreCGG cortical astrocytes (∼170 CGG repeats) displayed 3-fold higher Fmr1 mRNA and 30% lower FMR1 protein (FMRP) when compared with WT. PreCGG astrocytes showed modest reductions in expression of glutamate (Glu) transporters GLT-1 and GLAST and attenuated Glu uptake (p < 0.01). Consistent with astrocyte cultures in vitro, aged preCGG mice cerebral cortex also displayed reduced GLAST and GLT-1 expression. Approximately 65% of the WT and preCGG cortical astrocytes displayed spontaneous asynchronous Ca(2+) oscillations. PreCGG astrocytes exhibited nearly 50% higher frequency of asynchronous Ca(2+) oscillations (p < 0.01) than WT, a difference mimicked by chronic exposure of WT astrocytes to l-trans-pyrrolidine-2,4-dicarboxylic acid (l-trans-PDC) or by partial suppression of GLAST using siRNA interference. Acute challenge with Glu augmented the frequency of Ca(2+) oscillations in both genotypes. Additionally, 10 μm Glu elicited a sustained intracellular Ca(2+) rise in a higher portion of preCGG astrocytes when compared with WT. Pharmacological studies showed that mGluR5, but not NMDA receptor, contributed to Glu hypersensitivity in preCGG astrocytes. These functional defects in preCGG astrocytes, especially in Glu signaling, may contribute to fragile X-associated tremor/ataxia syndrome neuropathology.
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Affiliation(s)
- Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine, University ofCalifornia, Davis, California 95616, USA.
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Sellier C, Freyermuth F, Tabet R, Tran T, He F, Ruffenach F, Alunni V, Moine H, Thibault C, Page A, Tassone F, Willemsen R, Disney MD, Hagerman PJ, Todd PK, Charlet-Berguerand N. Sequestration of DROSHA and DGCR8 by expanded CGG RNA repeats alters microRNA processing in fragile X-associated tremor/ataxia syndrome. Cell Rep 2013; 3:869-80. [PMID: 23478018 DOI: 10.1016/j.celrep.2013.02.004] [Citation(s) in RCA: 190] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 11/30/2012] [Accepted: 02/01/2013] [Indexed: 11/19/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is an inherited neurodegenerative disorder caused by the expansion of 55-200 CGG repeats in the 5' UTR of FMR1. These expanded CGG repeats are transcribed and accumulate in nuclear RNA aggregates that sequester one or more RNA-binding proteins, thus impairing their functions. Here, we have identified that the double-stranded RNA-binding protein DGCR8 binds to expanded CGG repeats, resulting in the partial sequestration of DGCR8 and its partner, DROSHA, within CGG RNA aggregates. Consequently, the processing of microRNAs (miRNAs) is reduced, resulting in decreased levels of mature miRNAs in neuronal cells expressing expanded CGG repeats and in brain tissue from patients with FXTAS. Finally, overexpression of DGCR8 rescues the neuronal cell death induced by expression of expanded CGG repeats. These results support a model in which a human neurodegenerative disease originates from the alteration, in trans, of the miRNA-processing machinery.
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Affiliation(s)
- Chantal Sellier
- Department of Translational Medicine, IGBMC, Illkirch 67400, France
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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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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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46
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Lu C, Lin L, Tan H, Wu H, Sherman SL, Gao F, Jin P, Chen D. Fragile X premutation RNA is sufficient to cause primary ovarian insufficiency in mice. Hum Mol Genet 2012; 21:5039-47. [PMID: 22914733 DOI: 10.1093/hmg/dds348] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spontaneous 46,XX primary ovarian insufficiency (POI), also known as 'premature menopause' or 'premature ovarian failure', refers to ovarian dysfunction that results in a range of abnormalities, from infertility to early menopause as the end stage. The most common known genetic cause of POI is the expansion of a CGG repeat to 55-199 copies (premutation) in the 5' untranslated region in the X-linked fragile X mental retardation 1 (FMR1) gene. POI associated with the FMR1 premutation is referred to as fragile X-associated POI (FXPOI). Here, we characterize a mouse model carrying the human FMR1 premutation allele and show that FMR1 premutation RNA can cause a reduction in the number of growing follicles in ovaries and is sufficient to impair female fertility. Alterations in selective serum hormone levels, including FSH, LH and 17β-estradiol, are seen in this mouse model, which mimics findings in humans. In addition, we also find that LH-induced ovulation-related gene expression is specifically altered. Finally, we show that the FMR1 premutation allele can lead to reduced phosphorylation of Akt and mTOR proteins. These results together suggest that FMR1 premutation RNA could cause the POI associated with FMR1 premutation carriers, and the Akt/mTOR pathway may serve as a therapeutic target for FXPOI.
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Affiliation(s)
- Cuiling Lu
- State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, PR China
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47
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Winarni TI, Chonchaiya W, Sumekar TA, Ashwood P, Morales GM, Tassone F, Nguyen DV, Faradz SMH, Van de Water J, Cook K, Hamlin A, Mu Y, Hagerman PJ, Hagerman RJ. Immune-mediated disorders among women carriers of fragile X premutation alleles. Am J Med Genet A 2012; 158A:2473-81. [PMID: 22903889 DOI: 10.1002/ajmg.a.35569] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Accepted: 06/20/2012] [Indexed: 12/14/2022]
Abstract
The relative risk of immune-mediated disorders (IMDs) among women carriers of premutation alleles is estimated by a survey for IMDs among 344 carrier women (age 19-81 years; mean 46.35 and SD 12.60) and 72 controls (age 18-87 years; mean 52.40 and SD 15.40). One hundred fifty four (44.77%) women carrier had at least one IMD, as did 20 controls (27.78%). Among women carriers, autoimmune thyroid disorder was the most common (24.4%), then fibromyalgia (10.2%), irritable bowel syndrome (IBS; 9.9%), Raynaud's phenomenon (7.6%), rheumatoid arthritis (RA; 3.8%), Sjögren syndrome (2.6%), systemic lupus erythematosus (SLE; 2.03%), multiple sclerosis (1.74%). Of 55 carriers age 40 or older with FXTAS, 72.73% had at least one IMD, compared to 46.54% of those without FXTAS (n = 159), and 31.58% of controls (n = 57). The estimated odds ratio (OR) for IMD is 2.6 (95% CI 1.2-5.6, P = 0.015) for women with FXTAS relative to those without FXTAS; the likelihood of IMD in carriers without or with FXTAS was also significantly higher than for controls (OR 2.1, 95% CI 1.1-4.2, P = 0.034; OR 5.5, 95% CI 2.4-12.5, P < 0.001, respectively). Similarly, the odds of having an IMD among carriers with FXPOI is about 2.4 times higher when compared to carriers without FXPOI (95% CI 1.1-5.0; P = 0.021). The likelihood of IMD in carriers with or without FXPOI is greater (OR 2.4, 95% CI 1.1-5.0; P = 0.021) compared to that of controls.
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Affiliation(s)
- Tri Indah Winarni
- Medical Investigation of Neurodevelopmental Disorders Institute, University of California, Davis, Health System, Sacramento, USA
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48
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Mechanism of repeat-associated microRNAs in fragile X syndrome. Neural Plast 2012; 2012:104796. [PMID: 22779005 PMCID: PMC3388308 DOI: 10.1155/2012/104796] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/11/2012] [Accepted: 02/15/2012] [Indexed: 12/14/2022] Open
Abstract
The majority of the human genome is comprised of non-coding DNA, which frequently contains redundant microsatellite-like trinucleotide repeats. Many of these trinucleotide repeats are involved in triplet repeat expansion diseases (TREDs) such as fragile X syndrome (FXS). After transcription, the trinucleotide repeats can fold into RNA hairpins and are further processed by Dicer endoribonuclases to form microRNA (miRNA)-like molecules that are capable of triggering targeted gene-silencing effects in the TREDs. However, the function of these repeat-associated miRNAs (ramRNAs) is unclear. To solve this question, we identified the first native ramRNA in FXS and successfully developed a transgenic zebrafish model for studying its function. Our studies showed that ramRNA-induced DNA methylation of the FMR1 5′-UTR CGG trinucleotide repeat expansion is responsible for both pathological and neurocognitive characteristics linked to the transcriptional FMR1 gene inactivation and the deficiency of its protein product FMRP. FMRP deficiency often causes synapse deformity in the neurons essential for cognition and memory activities, while FMR1 inactivation augments metabotropic glutamate receptor (mGluR)-activated long-term depression (LTD), leading to abnormal neuronal responses in FXS. Using this novel animal model, we may further dissect the etiological mechanisms of TREDs, with the hope of providing insights into new means for therapeutic intervention.
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Hoffman GE, Le WW, Entezam A, Otsuka N, Tong ZB, Nelson L, Flaws JA, McDonald JH, Jafar S, Usdin K. Ovarian abnormalities in a mouse model of fragile X primary ovarian insufficiency. J Histochem Cytochem 2012; 60:439-56. [PMID: 22470123 PMCID: PMC3393073 DOI: 10.1369/0022155412441002] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 02/04/2012] [Indexed: 11/22/2022] Open
Abstract
FMR1 premutation (PM) alleles have 55-200 CGG·CCG-repeats in their 5' UTR. PM carriers are at risk of fragile X-associated tremor and ataxia syndrome (FXTAS). Females are also at risk for FX primary ovarian insufficiency (FXPOI). PM pathology is generally attributed to deleterious properties of transcripts with long CGG-tracts. For FXPOI, hormone changes suggest a reduced residual follicle pool. Whether this is due to a smaller than normal original follicle pool or an increased rate of follicle depletion is unclear. A FX-PM mouse the authors generated with 130 CGG·CCG-repeats in the endogenous Fmr1 gene recapitulates features of FXTAS. Here the authors demonstrate that the gross development of the ovary and the establishment of the primordial follicle pool is normal in these mice. However, these animals show a faster loss of follicles of all follicle classes, suggesting that the problem is intrinsic to the ovary. In addition, many oocytes show aberrant nuclear accumulation of FMRP and elevated levels of ubiquitination. Furthermore, PM follicles are smaller and have fewer granulosa cells (GCs) than normal. Thus, these animals have ovarian abnormalities involving both the oocytes and GCs that may shed light on the molecular basis of FXPOI in humans.
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Affiliation(s)
- Gloria E Hoffman
- Department of Biology, Morgan State University, Baltimore, MD 21251, USA.
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Hall DA, O'keefe JA. Fragile x-associated tremor ataxia syndrome: the expanding clinical picture, pathophysiology, epidemiology, and update on treatment. TREMOR AND OTHER HYPERKINETIC MOVEMENTS (NEW YORK, N.Y.) 2012; 2. [PMID: 23439567 PMCID: PMC3570061 DOI: 10.7916/d8hd7tds] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 11/21/2011] [Indexed: 12/12/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder characterized by kinetic tremor, cerebellar gait ataxia, parkinsonism, and cognitive decline. This disorder occurs in both males and females, frequently in families with children who have fragile X syndrome. The clinical features of this disorder, both classic and newly described, are summarized in this paper. In screening studies, fragile X mental retardation 1 (FMR1) gene premutation (55–200 CGG) expansions are most frequently seen in men with ataxia who have tested negative for spinocerebellar ataxias. Since the original description, the classic FXTAS phenotype has now been reported in females and in carriers of smaller (45–54 CGG) and larger (>200 CGG) expansions in FMR1. Premutation carriers may present with a Parkinson disease phenotype or hypotension, rather than with tremor and/or ataxia. Parkinsonism and gait ataxia may also be seen in individuals with gray zone (41–54 CGG) expansions. Studies regarding medication to treat the symptoms in FXTAS are few in number and suggest that medications targeted to specific symptoms, such as kinetic tremor or gait ataxia, may be most beneficial. Great progress has been made in regards to FXTAS research, likely given the readily available gene test and the screening of multiple family members, including parents and grandparents, of fragile X syndrome children. Expansion of genotypes and phenotypes in the disorder may suggest that a broader disease definition might be necessary in the future.
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Affiliation(s)
- Deborah A Hall
- Department of Neurological Sciences, Rush University, Chicago, Illinois, United States of America
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