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Jiraanont P, Zafarullah M, Sulaiman N, Espinal GM, Randol JL, Durbin-Johnson B, Schneider A, Hagerman RJ, Hagerman PJ, Tassone F. FMR1 Protein Expression Correlates with Intelligence Quotient in Both Peripheral Blood Mononuclear Cells and Fibroblasts from Individuals with an FMR1 Mutation. J Mol Diagn 2024; 26:498-509. [PMID: 38522837 DOI: 10.1016/j.jmoldx.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 02/15/2024] [Accepted: 02/23/2024] [Indexed: 03/26/2024] Open
Abstract
Fragile X syndrome (FXS) is the most common heritable form of intellectual disability and is caused by CGG repeat expansions exceeding 200 (full mutation). Such expansions lead to hypermethylation and transcriptional silencing of the fragile X messenger ribonucleoprotein 1 (FMR1) gene. As a consequence, little or no FMR1 protein (FMRP) is produced; absence of the protein, which normally is responsible for neuronal development and maintenance, causes the syndrome. Previous studies have demonstrated the causal relationship between FMRP levels and cognitive abilities in peripheral blood mononuclear cells (PBMCs) and dermal fibroblast cell lines of patients with FXS. However, it is arguable whether PBMCs or fibroblasts would be the preferred surrogate for measuring molecular markers, particularly FMRP, to represent the cognitive impairment, a core symptom of FXS. To address this concern, CGG repeats, methylation status, FMR1 mRNA, and FMRP levels were measured in both PBMCs and fibroblasts derived from 66 individuals. The findings indicated a strong association between FMR1 mRNA expression levels and CGG repeat numbers in PBMCs of premutation males after correcting for methylation status. Moreover, FMRP expression levels from both PBMCs and fibroblasts of male participants with a hypermethylated full mutation and with mosaicism demonstrated significant association between the intelligence quotient levels and FMRP levels, suggesting that PBMCs may be preferable for FXS clinical studies, because of their greater accessibility.
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Affiliation(s)
- Poonnada Jiraanont
- Division of Molecular and Cellular Medicine, Faculty of Medicine, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand
| | - Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California
| | - Noor Sulaiman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California
| | - Glenda M Espinal
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California
| | - Jamie L Randol
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California
| | - Blythe Durbin-Johnson
- Division of Biostatistics, University of California, Davis, School of Medicine, Davis, California
| | - Andrea Schneider
- Department of Pediatrics, University of California, Davis, School of Medicine, Davis, California; UC Davis MIND Institute, University of California, Davis, Sacramento, California
| | - Randi J Hagerman
- Department of Pediatrics, University of California, Davis, School of Medicine, Davis, California; UC Davis MIND Institute, University of California, Davis, Sacramento, California
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California; UC Davis MIND Institute, University of California, Davis, Sacramento, California
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California; UC Davis MIND Institute, University of California, Davis, Sacramento, California.
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Randol JL, Kim K, Ponzini MD, Tassone F, Falcon AK, Hagerman RJ, Hagerman PJ. Variation of FMRP Expression in Peripheral Blood Mononuclear Cells from Individuals with Fragile X Syndrome. Genes (Basel) 2024; 15:356. [PMID: 38540415 PMCID: PMC10969917 DOI: 10.3390/genes15030356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 03/02/2024] [Accepted: 03/08/2024] [Indexed: 04/07/2024] Open
Abstract
Fragile X syndrome (FXS) is the most common heritable cause of intellectual disability and autism spectrum disorder. The syndrome is often caused by greatly reduced or absent protein expression from the fragile X messenger ribonucleoprotein 1 (FMR1) gene due to expansion of a 5'-non-coding trinucleotide (CGG) element beyond 200 repeats (full mutation). To better understand the complex relationships among FMR1 allelotype, methylation status, mRNA expression, and FMR1 protein (FMRP) levels, FMRP was quantified in peripheral blood mononuclear cells for a large cohort of FXS (n = 154) and control (n = 139) individuals using time-resolved fluorescence resonance energy transfer. Considerable size and methylation mosaicism were observed among individuals with FXS, with FMRP detected only in the presence of such mosaicism. No sample with a minimum allele size greater than 273 CGG repeats had significant levels of FMRP. Additionally, an association was observed between FMR1 mRNA and FMRP levels in FXS samples, predominantly driven by those with the lowest FMRP values. This study underscores the complexity of FMR1 allelotypes and FMRP expression and prompts a reevaluation of FXS therapies aimed at reactivating large full mutation alleles that are likely not capable of producing sufficient FMRP to improve cognitive function.
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Affiliation(s)
- Jamie L. Randol
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Kyoungmi Kim
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, UC Davis Health, Sacramento, CA 95817, USA
- Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Matthew D. Ponzini
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, UC Davis Health, Sacramento, CA 95817, USA
- Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, UC Davis Health, Sacramento, CA 95817, USA
| | - Alexandria K. Falcon
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Randi J. Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, UC Davis Health, Sacramento, CA 95817, USA
- Department of Pediatrics, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Paul J. Hagerman
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA 95616, USA
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, UC Davis Health, Sacramento, CA 95817, USA
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3
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Tak Y, Schneider A, Santos E, Randol JL, Tassone F, Hagerman P, Hagerman RJ. Unmethylated Mosaic Full Mutation Males without Fragile X Syndrome. Genes (Basel) 2024; 15:331. [PMID: 38540390 PMCID: PMC10970065 DOI: 10.3390/genes15030331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 02/26/2024] [Accepted: 02/28/2024] [Indexed: 04/07/2024] Open
Abstract
Fragile X syndrome (FXS) is the leading inherited cause of intellectual disability (ID) and single gene cause of autism. Although most patients with FXS and the full mutation (FM) have complete methylation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene, some have mosaicism in methylation and/or CGG repeat size, and few have completely unmethylated FM alleles. Those with a complete lack of methylation are rare, with little literature about the cognitive and behavioral phenotypes of these individuals. A review of past literature was conducted regarding individuals with unmethylated and mosaic FMR1 FM. We report three patients with an unmethylated FM FMR1 alleles without any behavioral or cognitive deficits. This is an unusual presentation for men with FM as most patients with an unmethylated FM and no behavioral phenotypes do not receive fragile X DNA testing or a diagnosis of FXS. Our cases showed that mosaic males with unmethylated FMR1 FM alleles may lack behavioral phenotypes due to the presence of smaller alleles producing the FMR1 protein (FMRP). However, these individuals could be at a higher risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS) due to the increased expression of mRNA, similar to those who only have a premutation.
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Affiliation(s)
- YeEun Tak
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (Y.T.); (E.S.); (F.T.); (P.H.)
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Andrea Schneider
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Ellery Santos
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (Y.T.); (E.S.); (F.T.); (P.H.)
| | - Jamie Leah Randol
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (Y.T.); (E.S.); (F.T.); (P.H.)
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Paul Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (Y.T.); (E.S.); (F.T.); (P.H.)
- Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
| | - Randi J. Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA 95616, USA; (Y.T.); (E.S.); (F.T.); (P.H.)
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA 95817, USA;
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Elhawary NA, AlJahdali IA, Abumansour IS, Azher ZA, Falemban AH, Madani WM, Alosaimi W, Alghamdi G, Sindi IA. Phenotypic variability to medication management: an update on fragile X syndrome. Hum Genomics 2023; 17:60. [PMID: 37420260 DOI: 10.1186/s40246-023-00507-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023] Open
Abstract
This review discusses the discovery, epidemiology, pathophysiology, genetic etiology, molecular diagnosis, and medication-based management of fragile X syndrome (FXS). It also highlights the syndrome's variable expressivity and common comorbid and overlapping conditions. FXS is an X-linked dominant disorder associated with a wide spectrum of clinical features, including but not limited to intellectual disability, autism spectrum disorder, language deficits, macroorchidism, seizures, and anxiety. Its prevalence in the general population is approximately 1 in 5000-7000 men and 1 in 4000-6000 women worldwide. FXS is associated with the fragile X messenger ribonucleoprotein 1 (FMR1) gene located at locus Xq27.3 and encodes the fragile X messenger ribonucleoprotein (FMRP). Most individuals with FXS have an FMR1 allele with > 200 CGG repeats (full mutation) and hypermethylation of the CpG island proximal to the repeats, which silences the gene's promoter. Some individuals have mosaicism in the size of the CGG repeats or in hypermethylation of the CpG island, both produce some FMRP and give rise to milder cognitive and behavioral deficits than in non-mosaic individuals with FXS. As in several monogenic disorders, modifier genes influence the penetrance of FMR1 mutations and FXS's variable expressivity by regulating the pathophysiological mechanisms related to the syndrome's behavioral features. Although there is no cure for FXS, prenatal molecular diagnostic testing is recommended to facilitate early diagnosis. Pharmacologic agents can reduce some behavioral features of FXS, and researchers are investigating whether gene editing can be used to demethylate the FMR1 promoter region to improve patient outcomes. Moreover, clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 and developed nuclease defective Cas9 (dCas9) strategies have promised options of genome editing in gain-of-function mutations to rewrite new genetic information into a specified DNA site, are also being studied.
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Affiliation(s)
- Nasser A Elhawary
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia.
| | - Imad A AlJahdali
- Department of Community Medicine, College of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Iman S Abumansour
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Zohor A Azher
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Alaa H Falemban
- Department of Pharmacology and Toxicology, College of Medicine, Umm Al-Qura University, Mecca, 24382, Saudi Arabia
| | - Wefaq M Madani
- Department of Hematology and Immunology, Faculty of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Ghydda Alghamdi
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Ikhlas A Sindi
- Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Preparatory Year Program, Batterjee Medical College, Jeddah, 21442, Saudi Arabia
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5
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Godler DE, Inaba Y, Bui MQ, Francis D, Skinner C, Schwartz CE, Amor DJ. Defining the 3'Epigenetic Boundary of the FMR1 Promoter and Its Loss in Individuals with Fragile X Syndrome. Int J Mol Sci 2023; 24:10712. [PMID: 37445892 DOI: 10.3390/ijms241310712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/20/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
This study characterizes the DNA methylation patterns specific to fragile X syndrome (FXS) with a full mutation (FM > 200 CGGs), premutation (PM 55-199 CGGs), and X inactivation in blood and brain tissues at the 3' boundary of the FMR1 promoter. Blood was analyzed from 95 controls and 462 individuals (32% males) with FM and PM alleles. Brain tissues (62% males) were analyzed from 12 controls and 4 with FXS. There was a significant increase in intron 1 methylation, extending to a newly defined 3' epigenetic boundary in the FM compared with that in the control and PM groups (p < 0.0001), and this was consistent between the blood and brain tissues. A distinct intron 2 site showed a significant decrease in methylation for the FXS groups compared with the controls in both sexes (p < 0.01). In all female groups, most intron 1 (but not intron 2 sites) were sensitive to X inactivation. In all PM groups, methylation at the 3' epigenetic boundary and the proximal sites was significantly decreased compared with that in the control and FM groups (p < 0.0001). In conclusion, abnormal FMR1 intron 1 and 2 methylation that was sensitive to X inactivation in the blood and brain tissues provided a novel avenue for the detection of PM and FM alleles through DNA methylation analysis.
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Affiliation(s)
- David E Godler
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC 3052, Australia
| | - Yoshimi Inaba
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
| | - Minh Q Bui
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC 3052, Australia
| | - David Francis
- Victorian Clinical Genetics Services and Murdoch Children's Research Institute, The Royal Children's Hospital, Melbourne, VIC 3052, Australia
| | - Cindy Skinner
- Center for Molecular Studies, J.C. Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Charles E Schwartz
- Center for Molecular Studies, J.C. Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - David J Amor
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC 3052, Australia
- Neurodisability and Rehabilitation, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC 3052, Australia
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6
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Wright SE, Todd PK. Native functions of short tandem repeats. eLife 2023; 12:e84043. [PMID: 36940239 PMCID: PMC10027321 DOI: 10.7554/elife.84043] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/08/2023] [Indexed: 03/21/2023] Open
Abstract
Over a third of the human genome is comprised of repetitive sequences, including more than a million short tandem repeats (STRs). While studies of the pathologic consequences of repeat expansions that cause syndromic human diseases are extensive, the potential native functions of STRs are often ignored. Here, we summarize a growing body of research into the normal biological functions for repetitive elements across the genome, with a particular focus on the roles of STRs in regulating gene expression. We propose reconceptualizing the pathogenic consequences of repeat expansions as aberrancies in normal gene regulation. From this altered viewpoint, we predict that future work will reveal broader roles for STRs in neuronal function and as risk alleles for more common human neurological diseases.
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Affiliation(s)
- Shannon E Wright
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- Neuroscience Graduate Program, University of Michigan–Ann ArborAnn ArborUnited States
- Department of Neuroscience, Picower InstituteCambridgeUnited States
| | - Peter K Todd
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- VA Ann Arbor Healthcare SystemAnn ArborUnited States
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7
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Palumbo JM, Thomas BF, Budimirovic D, Siegel S, Tassone F, Hagerman R, Faulk C, O’Quinn S, Sebree T. Role of the endocannabinoid system in fragile X syndrome: potential mechanisms for benefit from cannabidiol treatment. J Neurodev Disord 2023; 15:1. [PMID: 36624400 PMCID: PMC9830713 DOI: 10.1186/s11689-023-09475-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 12/28/2022] [Indexed: 01/11/2023] Open
Abstract
Multiple lines of evidence suggest a central role for the endocannabinoid system (ECS) in the neuronal development and cognitive function and in the pathogenesis of fragile X syndrome (FXS). This review describes the ECS, its role in the central nervous system, how it is dysregulated in FXS, and the potential role of cannabidiol as a treatment for FXS. FXS is caused by deficiency or absence of the fragile X messenger ribonucleoprotein 1 (FMR1) protein, FMRP, typically due to the presence of >200 cytosine, guanine, guanine sequence repeats leading to methylation of the FMR1 gene promoter. The absence of FMRP, following FMR1 gene-silencing, disrupts ECS signaling, which has been implicated in FXS pathogenesis. The ECS facilitates synaptic homeostasis and plasticity through the cannabinoid receptor 1, CB1, on presynaptic terminals, resulting in feedback inhibition of neuronal signaling. ECS-mediated feedback inhibition and synaptic plasticity are thought to be disrupted in FXS, leading to overstimulation, desensitization, and internalization of presynaptic CB1 receptors. Cannabidiol may help restore synaptic homeostasis by acting as a negative allosteric modulator of CB1, thereby attenuating the receptor overstimulation, desensitization, and internalization. Moreover, cannabidiol affects DNA methylation, serotonin 5HT1A signal transduction, gamma-aminobutyric acid receptor signaling, and dopamine D2 and D3 receptor signaling, which may contribute to beneficial effects in patients with FXS. Consistent with these proposed mechanisms of action of cannabidiol in FXS, in the CONNECT-FX trial the transdermal cannabidiol gel, ZYN002, was associated with improvements in measures of social avoidance, irritability, and social interaction, particularly in patients who are most affected, showing ≥90% methylation of the FMR1 gene.
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Affiliation(s)
- Joseph M. Palumbo
- grid.422480.80000 0004 8307 0679Zynerba Pharmaceuticals Inc., Devon, PA USA
| | | | - Dejan Budimirovic
- grid.240023.70000 0004 0427 667XDepartments of Psychiatry and Neurogenetics, Fragile X Clinic, Kennedy Krieger Institute, Baltimore, MD USA ,grid.21107.350000 0001 2171 9311Department of Psychiatry & Behavioral Sciences-Child Psychiatry, Johns Hopkins School of Medicine, Baltimore, MD USA
| | - Steven Siegel
- grid.42505.360000 0001 2156 6853Department of Psychiatry and Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, CA USA
| | - Flora Tassone
- grid.413079.80000 0000 9752 8549Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California-Davis Medical Center, Sacramento, CA USA ,grid.413079.80000 0000 9752 8549Department of Biochemistry and Molecular Medicine, School of Medicine, University of California-Davis, Sacramento, CA USA
| | - Randi Hagerman
- grid.413079.80000 0000 9752 8549Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California-Davis Medical Center, Sacramento, CA USA ,grid.27860.3b0000 0004 1936 9684Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA USA
| | - Christopher Faulk
- grid.17635.360000000419368657Department of Animal Science, University of Minnesota, St. Paul, MN USA
| | - Stephen O’Quinn
- grid.422480.80000 0004 8307 0679Zynerba Pharmaceuticals Inc., Devon, PA USA
| | - Terri Sebree
- grid.422480.80000 0004 8307 0679Zynerba Pharmaceuticals Inc., Devon, PA USA
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Baud A, Derbis M, Tutak K, Sobczak K. Partners in crime: Proteins implicated in
RNA
repeat expansion diseases. WIRES RNA 2022; 13:e1709. [PMID: 35229468 PMCID: PMC9539487 DOI: 10.1002/wrna.1709] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/06/2022]
Affiliation(s)
- Anna Baud
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Magdalena Derbis
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Katarzyna Tutak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Krzysztof Sobczak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
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Famula J, Ferrer E, Hagerman RJ, Tassone F, Schneider A, Rivera SM, Hessl D. Neuropsychological changes in FMR1 premutation carriers and onset of fragile X-associated tremor/ataxia syndrome. J Neurodev Disord 2022; 14:23. [PMID: 35321639 PMCID: PMC8942145 DOI: 10.1186/s11689-022-09436-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/14/2022] [Indexed: 11/24/2022] Open
Abstract
Background Carriers of the FMR1 premutation are at increased risk of developing a late-onset progressive neurodegenerative disease, fragile X-associated tremor/ataxia syndrome (FXTAS), characterized by intention tremor, gait ataxia, and cognitive decline. Cross-sectional studies to date have provided evidence that neuropsychological changes, such as executive function alterations, or subtle motor changes, may precede the onset of formal FXTAS, perhaps characterizing a prodromal state. However, the lack of longitudinal data has prevented the field from forming a clear picture of progression over time within individuals, and we lack consensus regarding early markers of risk and measures that may be used to track response to intervention. Methods This was a longitudinal study of 64 male FMR1 premutation carriers (Pm) without FXTAS at study entry and 30 normal controls (Nc), aged 40 to 80 years (Pm M = 60.0 years; Nc M = 57.4 years). Fifty of the Pm and 22 of the Nc were re-assessed after an average of 2.33 years, and 37 Pm and 20 Nc were re-assessed a third time after an average of another 2.15 years. Eighteen of 64 carriers (28%) converted to FXTAS during the study to date. Neuropsychological assessments at each time point, including components of the Cambridge Neuropsychological Test Automated Battery (CANTAB), tapped domains of episodic and working memory, inhibitory control, visual attention, planning, executive control of movement, and manual speed and dexterity. Age-based mixed models were used to examine group differences in change over time on the outcomes in the full sample, and differences were further evaluated in 15 trios (n = 45; 15 Pm “converters,” 15 Pm “nonconverters,” 15 Nc) that were one-one matched on age, education, and socioeconomic status. Results Compared to Nc, Pm showed significantly greater rates of change over time in visual working memory, motor dexterity, inhibitory control, and manual movement speed. After multiple comparison correction, significant effects remained for motor dexterity. Worsening inhibitory control and slower manual movements were related to progression in FXTAS stage, but these effects became statistically non-significant after correcting for multiple comparisons. Higher FMR1 mRNA correlated with worsening manual reaction time but did not survive multiple comparisons and no other molecular measures correlated with neuropsychological changes. Finally, trio comparisons revealed greater rate of decline in planning and manual movement speed in Pm converters compared to Pm nonconverters. Conclusions Accelerated decline in executive function and subtle motor changes, likely mediated by frontocerebellar circuits, may precede, and then track with the emergence of formal FXTAS symptoms. Further research to develop and harmonize clinical assessment of FMR1 carriers across centers is needed to prepare for future prophylactic and treatment trials for this disorder.
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Affiliation(s)
- Jessica Famula
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA.,Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, CA, USA
| | - Emilio Ferrer
- Department of Psychology, University of California Davis, Davis, CA, USA
| | - Randi J Hagerman
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA.,Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, USA
| | - Flora Tassone
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA.,Department of Biochemistry and Molecular Medicine, University of California Davis School of Medicine, Davis, CA, USA
| | - Andrea Schneider
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA.,Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, USA
| | - Susan M Rivera
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA.,Department of Psychology, University of California Davis, Davis, CA, USA.,Center for Mind and Brain, University of California Davis, Davis, CA, USA
| | - David Hessl
- MIND Institute, University of California Davis Health, 2825 50th Street, Sacramento, CA, 95817, USA. .,Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, CA, USA.
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10
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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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11
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Ordemann GJ, Apgar CJ, Chitwood RA, Brager DH. Altered A-Type Potassium Channel Function Impairs Dendritic Spike Initiation and Temporoammonic Long-Term Potentiation in Fragile X Syndrome. J Neurosci 2021; 41:5947-5962. [PMID: 34083256 PMCID: PMC8265803 DOI: 10.1523/jneurosci.0082-21.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 04/19/2021] [Accepted: 04/26/2021] [Indexed: 01/14/2023] Open
Abstract
Fragile X syndrome (FXS) is the leading monogenetic cause of cognitive impairment and autism spectrum disorder. Area CA1 of the hippocampus receives current information about the external world from the entorhinal cortex via the temporoammonic (TA) pathway. Given its role in learning and memory, it is surprising that little is known about TA long-term potentiation (TA-LTP) in FXS. We found that TA-LTP was impaired in male fmr1 KO mice. Although there were no significant differences in basal synaptic transmission, synaptically evoked dendritic calcium signals were smaller in KO neurons. Using dendritic recording, we found no difference in complex spikes or pharmacologically isolated Ca2+ spikes; however, the threshold for fast, Na+-dependent dendritic spikes was depolarized in fmr1 KO mice. Cell-attached patch-clamp recordings found no difference in Na+ channels between wild-type and fmr1 KO CA1 dendrites. Dendritic spike threshold and TA-LTP were restored by blocking A-type K+ channels with either 150 µm Ba2+ or the more specific toxin AmmTx3. The impairment of TA-LTP shown here, coupled with previously described enhanced Schaffer collateral LTP, may contribute to spatial memory alterations in FXS. Furthermore, as both of these LTP phenotypes are attributed to changes in A-type K+ channels in FXS, our findings provide a potential therapeutic target to treat cognitive impairments in FXS.SIGNIFICANCE STATEMENT Alterations in synaptic function and plasticity are likely contributors to learning and memory impairments in many neurologic disorders. Fragile X syndrome is marked by dysfunctional learning and memory and changes in synaptic structure and function. This study shows a lack of LTP at temporoammonic synapses in CA1 neurons associated with biophysical differences in A-type K+ channels in fmr1 KO CA1 neurons. Our results, along with previous findings on A-type K+ channel effects on Schaffer collateral LTP, reveal differential effects of a single ion channelopathy on LTP at the two major excitatory pathways of CA1 pyramidal neurons. These findings expand our understanding of memory deficits in FXS and provide a potential therapeutic target for the treatment of memory dysfunction in FXS.
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Affiliation(s)
- Gregory J Ordemann
- Department of Neuroscience, Institute for Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
| | - Christopher J Apgar
- Department of Neuroscience, Institute for Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
| | - Raymond A Chitwood
- Department of Neuroscience, Institute for Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
| | - Darrin H Brager
- Department of Neuroscience, Institute for Neuroscience, Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
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12
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Payán-Gómez C, Ramirez-Cheyne J, Saldarriaga W. Variable Expressivity in Fragile X Syndrome: Towards the Identification of Molecular Characteristics That Modify the Phenotype. Appl Clin Genet 2021; 14:305-312. [PMID: 34262328 PMCID: PMC8273740 DOI: 10.2147/tacg.s265835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/21/2021] [Indexed: 12/18/2022] Open
Abstract
Fragile X syndrome (FXS), is an X-linked inherited genetic disease. FXS is the leading cause of inherited intellectual disability and autism in the world. Those affected are characterized by intellectual disability, language deficit, typical facies, and macroorchidism. Alterations in the FMR1 gene have been associated with FXS. The majority of people with this condition have an allele with an expansion of more than 200 repeats in a tract of CGGs within the 5' untranslated region, and this expansion is associated with a hypermethylated state of the gene promoter. FXS has incomplete penetrance and variable expressivity. Intellectual disability is present in 100% of males and 60% of females. Autism spectrum disorder symptoms appear in 50% to 60% of males and 20% of females. Other characteristics such as behavioral and physical alterations have significant variations in presentation frequency. The molecular causes of the variable phenotype in FXS patients are becoming clear: these causes are related to the FMR1 gene itself and to secondary, modifying gene effects. In FXS patients, size and methylation mosaicisms are common. Secondary to mosaicism, there is a variation in the quantity of FMR1 mRNA and the protein coded by the gene Fragile Mental Retardation Protein (FMRP). Potential modifier genes have also been proposed, with conflicting results. Characterizing patients according to CGG expansion, methylation status, concentration of mRNA and FMRP, and genotypification for possible modifier genes in a clinical setting offers an opportunity to identify predictors for treatment response evaluation. When intervention strategies become available to modulate the course of the disease they could be crucial for selecting patients and identifying the best therapeutic intervention. The purpose of this review is to present the information available about the molecular causes of the variability of the expression incomplete penetrance and variable expressivity in FXS and their potential clinical applications.
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Affiliation(s)
- César Payán-Gómez
- Deparment of Biology, Faculty of Natural Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Julian Ramirez-Cheyne
- Health Faculty, Universidad del Valle, Cali, Colombia
- Hospital Universitario del Valle, Cali, Colombia
| | - Wilmar Saldarriaga
- Health Faculty, Universidad del Valle, Cali, Colombia
- Hospital Universitario del Valle, Cali, Colombia
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13
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Bhat SA, Yousuf A, Mushtaq Z, Kumar V, Qurashi A. Fragile X Premutation rCGG Repeats Impair Synaptic Growth and Synaptic Transmission at Drosophila larval Neuromuscular Junction. Hum Mol Genet 2021; 30:1677-1692. [PMID: 33772546 DOI: 10.1093/hmg/ddab087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/21/2021] [Accepted: 03/22/2021] [Indexed: 11/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disease that develops in some premutation (PM) carriers of the FMR1 gene with alleles bearing 55-200 CGG repeats. The discovery of a broad spectrum of clinical and cell developmental abnormalities among PM carriers with or without FXTAS and in model systems suggests that neurodegeneration seen in FXTAS could be the inevitable end-result of pathophysiological processes set during early development. Hence, it is imperative to trace early PM-induced pathological abnormalities. Previous studies have shown that transgenic Drosophila carrying PM-length CGG repeats are sufficient to cause neurodegeneration. Here, we used the same transgenic model to understand the effect of CGG repeats on the structure and function of the developing nervous system. We show that presynaptic expression of CGG repeats restricts synaptic growth, reduces the number of synaptic boutons, leads to aberrant presynaptic varicosities, and impairs synaptic transmission at the larval neuromuscular junctions. The postsynaptic analysis shows that both glutamate receptors and subsynaptic reticulum proteins were normal. However, a high percentage of boutons show a reduced density of Bruchpilot protein, a key component of presynaptic active zones required for vesicle release. The electrophysiological analysis shows a significant reduction in quantal content, a measure of total synaptic vesicles released per excitation potential. Together, these findings suggest that synapse perturbation caused by rCGG repeats mediates presynaptically during larval NMJ development. We also suggest that the stress-activated c-Jun N-terminal kinase protein Basket and CIDE-N protein Drep-2 positively mediate Bruchpilot active zone defects caused by rCGG repeats.
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Affiliation(s)
- Sajad A Bhat
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Aadil Yousuf
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
| | - Zeeshan Mushtaq
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Vimlesh Kumar
- Laboratory of Neurogenetics, IISER-Bhopal, Bhopal, MP, 462066, India
| | - Abrar Qurashi
- Department of Biotechnology, University of Kashmir, Srinagar, JK, 190006, India
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14
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Urine-Derived Epithelial Cell Lines: A New Tool to Model Fragile X Syndrome (FXS). Cells 2020; 9:cells9102240. [PMID: 33027907 PMCID: PMC7600987 DOI: 10.3390/cells9102240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/29/2020] [Accepted: 10/02/2020] [Indexed: 02/08/2023] Open
Abstract
Fragile X syndrome (FXS) is an X-linked neurodevelopmental condition associated with intellectual disability and behavioral problems due to the lack of the Fragile X mental retardation protein (FMRP), which plays a crucial role in synaptic plasticity and memory. A desirable in vitro cell model to study FXS would be one that can be generated by simple isolation and culture method from a collection of a non-invasive donor specimen. Currently, the various donor-specific cells can be isolated mainly from peripheral blood and skin biopsy. However, they are somewhat invasive methods for establishing cell lines from the primary subject material. In this study, we characterized a cost-effective and straightforward method to derive epithelial cell lines from urine samples collected from participants with FXS and healthy controls (TD). The urine-derived cells expressed epithelial cell surface markers via fluorescence-activated cell sorting (FACS). We observed inter, and the intra-tissue CGG mosaicism in the PBMCs and the urine-derived cells from participants with FXS potentially related to the observed variations in the phenotypic and clinical presentation FXS. We characterized these urine-derived epithelial cells for FMR1 mRNA and FMRP expression and observed some expression in the lines derived from full mutation mosaic participants. Further, FMRP expression was localized in the cytoplasm of the urine-derived epithelial cells of healthy controls. Deficient FMRP expression was also observed in mosaic males, while, as expected, no expression was observed in cells derived from participants with a hypermethylated full mutation.
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15
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Malecki C, Hambly BD, Jeremy RW, Robertson EN. The RNA-binding fragile-X mental retardation protein and its role beyond the brain. Biophys Rev 2020; 12:903-916. [PMID: 32654068 DOI: 10.1007/s12551-020-00730-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/06/2020] [Indexed: 12/17/2022] Open
Abstract
It is well-established that variations of a CGG repeat expansion in the gene FMR1, which encodes the fragile-X mental retardation protein (FMRP), cause the neurocognitive disorder, fragile-X syndrome (FXS). However, multiple observations suggest a general and complex regulatory role of FMRP in processes outside the brain: (1) FMRP is ubiquitously expressed in the body, suggesting it functions in multiple organ systems; (2) patients with FXS can exhibit a physical phenotype that is consistent with an underlying abnormality in connective tissue; (3) different CGG repeat expansion lengths in FMR1 result in different clinical outcomes due to different pathogenic mechanisms; (4) the function of FMRP as an RNA-binding protein suggests it has a general regulatory role. This review details the complex nature of FMRP and the different CGG repeat expansion lengths and the evidence supporting the essential role of the protein in a variety of biological and pathological processes.
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Affiliation(s)
- Cassandra Malecki
- Discipline of Pathology and Bosch Institute, The University of Sydney, Level 4 West, Charles Perkins Centre D17, Sydney, NSW, 2006, Australia.
| | - Brett D Hambly
- Discipline of Pathology and Bosch Institute, The University of Sydney, Level 4 West, Charles Perkins Centre D17, Sydney, NSW, 2006, Australia
| | - Richmond W Jeremy
- Discipline of Pathology and Bosch Institute, The University of Sydney, Level 4 West, Charles Perkins Centre D17, Sydney, NSW, 2006, Australia.,Cardiology Department, Royal Prince Alfred Hospital, Sydney, NSW, Australia
| | - Elizabeth N Robertson
- Discipline of Pathology and Bosch Institute, The University of Sydney, Level 4 West, Charles Perkins Centre D17, Sydney, NSW, 2006, Australia.,Cardiology Department, Royal Prince Alfred Hospital, Sydney, NSW, Australia
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16
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Rodriguez CM, Wright SE, Kearse MG, Haenfler JM, Flores BN, Liu Y, Ifrim MF, Glineburg MR, Krans A, Jafar-Nejad P, Sutton MA, Bassell GJ, Parent JM, Rigo F, Barmada SJ, Todd PK. A native function for RAN translation and CGG repeats in regulating fragile X protein synthesis. Nat Neurosci 2020; 23:386-397. [PMID: 32066985 PMCID: PMC7668390 DOI: 10.1038/s41593-020-0590-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/10/2020] [Indexed: 02/07/2023]
Abstract
Repeat-associated non-AUG-initiated translation of expanded CGG repeats (CGG RAN) from the FMR1 5'-leader produces toxic proteins that contribute to neurodegeneration in fragile X-associated tremor/ataxia syndrome. Here we describe how unexpanded CGG repeats and their translation play conserved roles in regulating fragile X protein (FMRP) synthesis. In neurons, CGG RAN acts as an inhibitory upstream open reading frame to suppress basal FMRP production. Activation of mGluR5 receptors enhances FMRP synthesis. This enhancement requires both the CGG repeat and CGG RAN initiation sites. Using non-cleaving antisense oligonucleotides (ASOs), we selectively blocked CGG RAN. This ASO blockade enhanced endogenous FMRP expression in human neurons. In human and rodent neurons, CGG RAN-blocking ASOs suppressed repeat toxicity and prolonged survival. These findings delineate a native function for CGG repeats and RAN translation in regulating basal and activity-dependent FMRP synthesis, and they demonstrate the therapeutic potential of modulating CGG RAN translation in fragile X-associated disorders.
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Affiliation(s)
- Caitlin M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Shannon E Wright
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Michael G Kearse
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Department of Biological Chemistry and Pharmacology, Center for RNA Biology, Ohio State University, Columbus, OH, USA
| | - Jill M Haenfler
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Brittany N Flores
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Yu Liu
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Marius F Ifrim
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Mary R Glineburg
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
| | | | - Michael A Sutton
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Jack M Parent
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- VA Ann Arbor Healthcare System, Ann Arbor, MI, USA
| | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA, USA
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Peter 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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17
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Kim K, Hessl D, Randol JL, Espinal GM, Schneider A, Protic D, Aydin EY, Hagerman RJ, Hagerman PJ. Association between IQ and FMR1 protein (FMRP) across the spectrum of CGG repeat expansions. PLoS One 2019; 14:e0226811. [PMID: 31891607 PMCID: PMC6938341 DOI: 10.1371/journal.pone.0226811] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/05/2019] [Indexed: 12/20/2022] Open
Abstract
Fragile X syndrome, the leading heritable form of intellectual disability, is caused by hypermethylation and transcriptional silencing of large (CGG) repeat expansions (> 200 repeats) in the 5′ untranslated region of the fragile X mental retardation 1 (FMR1) gene. As a consequence of FMR1 gene silencing, there is little or no production of FMR1 protein (FMRP), an important element in normal synaptic function. Although the absence of FMRP has long been known to be responsible for the cognitive impairment in fragile X syndrome, the relationship between FMRP level and cognitive ability (IQ) is only imprecisely understood. To address this issue, a high-throughput, fluorescence resonance energy transfer (FRET) assay has been used to quantify FMRP levels in dermal fibroblasts, and the relationship between FMRP and IQ measures was assessed by statistical analysis in a cohort of 184 individuals with CGG-repeat lengths spanning normal (< 45 CGGs) to full mutation (> 200 CGGs) repeat ranges in fibroblasts. The principal findings of the current study are twofold: i) For those with normal CGG repeats, IQ is no longer sensitive to further increases in FMRP above an FMRP threshold of ~70% of the mean FMRP level; below this threshold, IQ decreases steeply with further decreases in FMRP; and ii) For the current cohort, a mean IQ of 85 (lower bound for the normal IQ range) is attained for FMRP levels that are only ~35% of the mean FMRP level among normal CGG-repeat controls. The current results should help guide expectations for efforts to induce FMR1 gene activity and for the levels of cognitive function expected for a given range of FMRP levels.
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Affiliation(s)
- Kyoungmi Kim
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - David Hessl
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Jamie L. Randol
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - Glenda M. Espinal
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - Andrea Schneider
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Pediatrics, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Dragana Protic
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
| | - Elber Yuksel Aydin
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
| | - Randi J. Hagerman
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Pediatrics, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Paul J. Hagerman
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
- * E-mail:
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18
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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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19
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Huang G, Zhu H, Wu S, Cui M, Xu T. Long Noncoding RNA Can Be a Probable Mechanism and a Novel Target for Diagnosis and Therapy in Fragile X Syndrome. Front Genet 2019; 10:446. [PMID: 31191598 PMCID: PMC6541098 DOI: 10.3389/fgene.2019.00446] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 04/30/2019] [Indexed: 01/06/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common congenital hereditary disease of low intelligence after Down syndrome. Its main pathogenic gene is fragile X mental retardation 1 (FMR1) gene associated with intellectual disability, autism, and fragile X-related primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS). FMR1 gene transcription leads to the absence of fragile X mental retardation protein (FMRP). How to relieve or cure disorders associated with FXS has also become a clinically disturbing problem. Previous studies have recently shown that long noncoding RNAs (lncRNAs) contribute to the pathogenesis. And it has been identified that several lncRNAs including FMR4, FMR5, and FMR6 contribute to developing FXPOI/FXTAS, originating from the FMR1 gene locus. FMR4 is a product of RNA polymerase II and can regulate the expression of relevant genes during differentiation of human neural precursor cells. FMR5 is a sense-oriented transcript while FMR6 is an antisense lncRNA produced by the 3' UTR of FMR1. FMR6 is likely to contribute to developing FXPOI, and it overlaps exons 15-17 of FMR1 as well as two microRNA binding sites. Additionally, BC1 can bind FMRP to form an inhibitory complex and lncRNA TUG1 also can control axonal development by directly interacting with FMRP through modulating SnoN-Ccd1 pathway. Therefore, these lncRNAs provide pharmaceutical targets and novel biomarkers. This review will: (1) describe the clinical manifestations and traditional pathogenesis of FXS and FXTAS/FXPOI; (2) summarize what is known about the role of lncRNAs in the pathogenesis of FXS and FXTAS/FXPOI; and (3) provide an outlook of potential effects and future directions of lncRNAs in FXS and FXTAS/FXPOI researches.
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Affiliation(s)
- Ge Huang
- The Second Hospital of Jilin University, Changchun, China
| | - He Zhu
- The Second Hospital of Jilin University, Changchun, China
| | - Shuying Wu
- The Second Hospital of Jilin University, Changchun, China
| | - Manhua Cui
- The Second Hospital of Jilin University, Changchun, China
| | - Tianmin Xu
- The Second Hospital of Jilin University, Changchun, China
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20
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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: 54] [Impact Index Per Article: 9.0] [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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21
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Jiraanont P, Kumar M, Tang HT, Espinal G, Hagerman PJ, Hagerman RJ, Chutabhakdikul N, Tassone F. Size and methylation mosaicism in males with Fragile X syndrome. Expert Rev Mol Diagn 2018; 17:1023-1032. [PMID: 28929824 DOI: 10.1080/14737159.2017.1377612] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Size and methylation mosaicism are a common phenomenon in Fragile X syndrome (FXS). Here, the authors report a study on twelve fragile X males with atypical mosaicism, seven of whom presented with autism spectrum disorder. METHODS A combination of Southern Blot and PCR analysis was used for CGG allele sizing and methylation. FMR1 mRNA and FMRP expression were measured by qRT-PCR and by Homogeneous Time Resolved Fluorescence methodology, respectively. RESULTS DNA analysis showed atypical size- or methylation-mosaicism with both, full mutation and smaller (normal to premutation) alleles, as well as a combination of methylated and unmethylated alleles. Four individuals carried a deletion of the CGG repeat and portions of the flanking regions. The extent of methylation among the participants was reflected in the lower FMR1 mRNA and FMRP expression levels detected in these subjects. CONCLUSION Decreased gene expression is likely the main contributor to the cognitive impairment observed in these subjects; although the presence of a normal allele did not appear to compensate for the presence of the full mutation, it correlated with better cognitive function in some but not all of the reported cases emphasizing the complexity of the molecular and clinical profile in FXS.
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Affiliation(s)
- Poonnada Jiraanont
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA.,b Research Center for Neuroscience, Institute of Molecular Biosciences , Mahidol University , Nakornpathom , Thailand
| | - Madhur Kumar
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA
| | - Hiu-Tung Tang
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA
| | - Glenda Espinal
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA
| | - Paul J Hagerman
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA.,c M.I.N.D. Institute , University of California Davis Medical Center , Sacramento , CA , USA
| | - Randi J Hagerman
- c M.I.N.D. Institute , University of California Davis Medical Center , Sacramento , CA , USA.,d Department of Pediatrics , University of California, Davis Medical Center , Sacramento , CA , USA
| | - Nuanchan Chutabhakdikul
- b Research Center for Neuroscience, Institute of Molecular Biosciences , Mahidol University , Nakornpathom , Thailand
| | - Flora Tassone
- a Department of Biochemistry and Molecular Medicine , University of California, School of Medicine , Davis , CA , USA.,c M.I.N.D. Institute , University of California Davis Medical Center , Sacramento , CA , USA
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22
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Dahlhaus R. Of Men and Mice: Modeling the Fragile X Syndrome. Front Mol Neurosci 2018; 11:41. [PMID: 29599705 PMCID: PMC5862809 DOI: 10.3389/fnmol.2018.00041] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/31/2018] [Indexed: 12/26/2022] Open
Abstract
The Fragile X Syndrome (FXS) is one of the most common forms of inherited intellectual disability in all human societies. Caused by the transcriptional silencing of a single gene, the fragile x mental retardation gene FMR1, FXS is characterized by a variety of symptoms, which range from mental disabilities to autism and epilepsy. More than 20 years ago, a first animal model was described, the Fmr1 knock-out mouse. Several other models have been developed since then, including conditional knock-out mice, knock-out rats, a zebrafish and a drosophila model. Using these model systems, various targets for potential pharmaceutical treatments have been identified and many treatments have been shown to be efficient in preclinical studies. However, all attempts to turn these findings into a therapy for patients have failed thus far. In this review, I will discuss underlying difficulties and address potential alternatives for our future research.
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Affiliation(s)
- Regina Dahlhaus
- Institute for Biochemistry, Emil-Fischer Centre, University of Erlangen-Nürnberg, Erlangen, Germany
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23
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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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24
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Transmission of double FMR1 allelic premutations in a family. Genes Genomics 2017. [DOI: 10.1007/s13258-016-0506-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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25
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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: 162] [Impact Index Per Article: 23.1] [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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26
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Gossett A, Sansone S, Schneider A, Johnston C, Hagerman R, Tassone F, Rivera SM, Seritan AL, Hessl D. Psychiatric disorders among women with the fragile X premutation without children affected by fragile X syndrome. Am J Med Genet B Neuropsychiatr Genet 2016; 171:1139-1147. [PMID: 27615674 PMCID: PMC6907071 DOI: 10.1002/ajmg.b.32496] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 08/19/2016] [Indexed: 11/07/2022]
Abstract
Several studies have demonstrated increased rates of anxiety and depressive disorders among female carriers of the fragile X premutation. However, the majority of these studies focused on mothers of children with fragile X syndrome, who experience higher rates of parenting stress that may contribute to the emergence of these disorders. The present study compared psychiatric symptom presentation (utilizing measures of current symptoms and lifetime DSM-IV Axis I disorders) in 24 female carriers without affected children (mean age = 32.1 years) to 26 non-carrier women from the community (mean age = 30.5 years). We also examined the association between CGG repeat size (adjusted for X activation ratio) and mRNA, with severity of psychiatric symptoms. Women with the premutation reported significantly elevated symptoms of anxiety, depression, interpersonal sensitivity, obsessive-compulsiveness, and somatization relative to controls during the past week. Carriers had significantly higher rates of lifetime social phobia (42.3%) compared to controls (12.5%); however, this comparison did not remain significant after multiple comparison adjustment. Rates of other psychiatric disorders were not significantly elevated relative to controls, though it should be noted that lifetime rates among controls were much higher than previously published population estimates. Although the sample is relatively small, the study of this unique cohort suggests the premutation confers risk for mood and anxiety disorders independent of the stress of parenting children with FXS. Screening for psychiatric disorders in women with the premutation, even before they become parents, is important and highly encouraged. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Amy Gossett
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychology, California School of Professional Psychology, Alliant International University, Sacramento, California
| | - Stephanie Sansone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, California
| | - Andrea Schneider
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, California
| | - Cindy Johnston
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, California
| | - Randi Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, California
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, California
| | - Susan M. Rivera
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychology, University of California Davis, Davis, California
- Center for Mind and Brain, University of California Davis, Davis, California
| | - Andreea L. Seritan
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, California
| | - David Hessl
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California
- Department of Psychiatry and Behavioral Sciences, University of California Davis School of Medicine, Sacramento, California
- Correspondence to: David Hessl, Ph.D., Department of Psychiatry and Behavioral Sciences, MIND Institute, UC Davis, 2825 50th St., Sacramento, CA 95817.
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27
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Molecular Correlates and Recent Advancements in the Diagnosis and Screening of FMR1-Related Disorders. Genes (Basel) 2016; 7:genes7100087. [PMID: 27754417 PMCID: PMC5083926 DOI: 10.3390/genes7100087] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/06/2016] [Accepted: 10/08/2016] [Indexed: 12/12/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common monogenic cause of intellectual disability and autism. Molecular diagnostic testing of FXS and related disorders (fragile X-associated primary ovarian insufficiency (FXPOI) and fragile X-associated tremor/ataxia syndrome (FXTAS)) relies on a combination of polymerase chain reaction (PCR) and Southern blot (SB) for the fragile X mental retardation 1 (FMR1) CGG-repeat expansion and methylation analyses. Recent advancements in PCR-based technologies have enabled the characterization of the complete spectrum of CGG-repeat mutation, with or without methylation assessment, and, as a result, have reduced our reliance on the labor- and time-intensive SB, which is the gold standard FXS diagnostic test. The newer and more robust triplet-primed PCR or TP-PCR assays allow the mapping of AGG interruptions and enable the predictive analysis of the risks of unstable CGG expansion during mother-to-child transmission. In this review, we have summarized the correlation between several molecular elements, including CGG-repeat size, methylation, mosaicism and skewed X-chromosome inactivation, and the extent of clinical involvement in patients with FMR1-related disorders, and reviewed key developments in PCR-based methodologies for the molecular diagnosis of FXS, FXTAS and FXPOI, and large-scale (CGG)n expansion screening in newborns, women of reproductive age and high-risk populations.
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Song G, Napoli E, Wong S, Hagerman R, Liu S, Tassone F, Giulivi C. Altered redox mitochondrial biology in the neurodegenerative disorder fragile X-tremor/ataxia syndrome: use of antioxidants in precision medicine. Mol Med 2016; 22:548-559. [PMID: 27385396 DOI: 10.2119/molmed.2016.00122] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/23/2016] [Indexed: 11/06/2022] Open
Abstract
A 55-200 expansion of the CGG nucleotide repeat in the 5'-UTR of the fragile X mental retardation 1 gene (FMR1) is the hallmark of the triplet nucleotide disease known as the "premutation" as opposed to those with >200 repeats, known as the full mutation or fragile X syndrome. Originally, premutation carriers were thought to be free of phenotypic traits; however, some are diagnosed with emotional and neurocognitive issues and, later in life, with the neurodegenerative disease fragile X-associated tremor/ataxia syndrome (FXTAS). Considering that mitochondrial dysfunction has been observed in fibroblasts and post-mortem brain samples from carriers of the premutation, we hypothesized that mitochondrial dysfunction-derived ROS may result in cumulative oxidative-nitrative damage. Fibroblasts from premutation carriers (n=31, all FXTAS-free except 8), compared to age- and sex-matched controls (n=25), showed increased mitochondrial ROS production, impaired Complex I activity, lower expression of MIA40 (rate-limiting step of the redox-regulated mitochondrial-disulfide-relay-system), increased mtDNA deletions, and increased biomarkers of lipid and protein oxidative-nitrative damage. Most of the outcomes were more pronounced in FXTAS-affected individuals. Significant recovery of mitochondrial mass and/or function was obtained with superoxide or hydroxyl radicals' scavengers, a glutathione peroxidase analog, or by overexpressing MIA40. The effects of ethanol (a hydroxyl radical scavenger) were deleterious, while others (by N-acetyl-cysteine, quercetin and epigallocatechin-3-gallate) were outcome- and/or carrier-specifics. The use of antioxidants in the context of precision medicine is discussed with the goal of improving mitochondrial function in carriers with the potential of decreasing the morbidity and/or delaying FXTAS onset.
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Affiliation(s)
- Gyu Song
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616
| | - Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616
| | - Sarah Wong
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616
| | - Randi Hagerman
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, CA 95817.,Department of Pediatrics, University of California Davis Medical Center, Sacramento CA 95817
| | - Siming Liu
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616
| | - Flora Tassone
- Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, CA 95817.,Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, CA 95817
| | - Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616.,Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, CA 95817
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Abstract
Many physicians are unaware of the many phenotypes associated with the fragile X premutation, an expansion in the 5' untranslated region of the fragile X mental retardation 1 (FMR1) gene that consists of 55-200 CGG repeats. The most severe of these phenotypes is fragile X-associated tremor/ataxia syndrome (FXTAS), which occurs in the majority of ageing male premutation carriers but in fewer than 20% of ageing women with the premutation. The prevalence of the premutation is 1 in 150-300 females, and 1 in 400-850 males, so physicians are likely to see people affected by FXTAS. Fragile X DNA testing is broadly available in the Western world. The clinical phenotype of FXTAS at presentation can vary and includes intention tremor, cerebellar ataxia, neuropathic pain, memory and/or executive function deficits, parkinsonian features, and psychological disorders, such as depression, anxiety and/or apathy. FXTAS causes brain atrophy and white matter disease, usually in the middle cerebellar peduncles, the periventricular area, and the splenium and/or genu of the corpus callosum. Here, we review the complexities involved in the clinical management of FXTAS and consider how targeted treatment for these clinical features of FXTAS will result from advances in our understanding of the molecular mechanisms that underlie this neurodegenerative disorder. Such targeted approaches should also be more broadly applicable to earlier forms of clinical involvement among premutation carriers.
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Napoli E, Ross-Inta C, Song G, Wong S, Hagerman R, Gane LW, Smilowitz JT, Tassone F, Giulivi C. Premutation in the Fragile X Mental Retardation 1 (FMR1) Gene Affects Maternal Zn-milk and Perinatal Brain Bioenergetics and Scaffolding. Front Neurosci 2016; 10:159. [PMID: 27147951 PMCID: PMC4835505 DOI: 10.3389/fnins.2016.00159] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/29/2016] [Indexed: 12/12/2022] Open
Abstract
Fragile X premutation alleles have 55–200 CGG repeats in the 5′ UTR of the FMR1 gene. Altered zinc (Zn) homeostasis has been reported in fibroblasts from >60 years old premutation carriers, in which Zn supplementation significantly restored Zn-dependent mitochondrial protein import/processing and function. Given that mitochondria play a critical role in synaptic transmission, brain function, and cognition, we tested FMRP protein expression, brain bioenergetics, and expression of the Zn-dependent synaptic scaffolding protein SH3 and multiple ankyrin repeat domains 3 (Shank3) in a knock-in (KI) premutation mouse model with 180 CGG repeats. Mitochondrial outcomes correlated with FMRP protein expression (but not FMR1 gene expression) in KI mice and human fibroblasts from carriers of the pre- and full-mutation. Significant deficits in brain bioenergetics, Zn levels, and Shank3 protein expression were observed in the Zn-rich regions KI hippocampus and cerebellum at PND21, with some of these effects lasting into adulthood (PND210). A strong genotype × age interaction was observed for most of the outcomes tested in hippocampus and cerebellum, whereas in cortex, age played a major role. Given that the most significant effects were observed at the end of the lactation period, we hypothesized that KI milk might have a role at compounding the deleterious effects on the FMR1 genetic background. A higher gene expression of ZnT4 and ZnT6, Zn transporters abundant in brain and lactating mammary glands, was observed in the latter tissue of KI dams. A cross-fostering experiment allowed improving cortex bioenergetics in KI pups nursing on WT milk. Conversely, WT pups nursing on KI milk showed deficits in hippocampus and cerebellum bioenergetics. A highly significant milk type × genotype interaction was observed for all three-brain regions, being cortex the most influenced. Finally, lower milk-Zn levels were recorded in milk from lactating women carrying the premutation as well as other Zn-related outcomes (Zn-dependent alkaline phosphatase activity and lactose biosynthesis—whose limiting step is the Zn-dependent β-1,4-galactosyltransferase). In premutation carriers, altered Zn homeostasis, brain bioenergetics and Shank3 levels could be compounded by Zn-deficient milk, increasing the risk of developing emotional and neurological/cognitive problems and/or FXTAS later in life.
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Affiliation(s)
- Eleonora Napoli
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Catherine Ross-Inta
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Gyu Song
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Sarah Wong
- Department of Molecular Biosciences, School of Veterinary Medicine Davis, CA, USA
| | - Randi Hagerman
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA; Department of Pediatrics, University of California Davis Medical CenterSacramento, CA, USA
| | - Louise W Gane
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, Davis Davis, CA, USA
| | - Jennifer T Smilowitz
- Department of Food Science and Technology and Foods for Health Institute, University of California, Davis Davis, CA, USA
| | - Flora Tassone
- Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA; Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, DavisDavis, CA, USA
| | - Cecilia Giulivi
- Department of Molecular Biosciences, School of Veterinary MedicineDavis, CA, USA; Medical Investigations of Neurodevelopmental Disorders Institute, University of California, DavisDavis, CA, USA
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Green KM, Linsalata AE, Todd PK. RAN translation-What makes it run? Brain Res 2016; 1647:30-42. [PMID: 27060770 DOI: 10.1016/j.brainres.2016.04.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 03/24/2016] [Accepted: 04/01/2016] [Indexed: 12/14/2022]
Abstract
Nucleotide-repeat expansions underlie a heterogeneous group of neurodegenerative and neuromuscular disorders for which there are currently no effective therapies. Recently, it was discovered that such repetitive RNA motifs can support translation initiation in the absence of an AUG start codon across a wide variety of sequence contexts, and that the products of these atypical translation initiation events contribute to neuronal toxicity. This review examines what we currently know and do not know about repeat associated non-AUG (RAN) translation in the context of established canonical and non-canonical mechanisms of translation initiation. We highlight recent findings related to RAN translation in three repeat expansion disorders: CGG repeats in fragile X-associated tremor ataxia syndrome (FXTAS), GGGGCC repeats in C9orf72 associated amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) and CAG repeats in Huntington disease. These studies suggest that mechanistic differences may exist for RAN translation dependent on repeat type, repeat reading frame, and the surrounding sequence context, but that for at least some repeats, RAN translation retains a dependence on some of the canonical translational initiation machinery. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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Affiliation(s)
- Katelyn M Green
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Alexander E Linsalata
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Peter K Todd
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States; Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI, United States; Veterans Affairs Medical Center, Ann Arbor, MI, United States.
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Conca Dioguardi C, Uslu B, Haynes M, Kurus M, Gul M, Miao DQ, De Santis L, Ferrari M, Bellone S, Santin A, Giulivi C, Hoffman G, Usdin K, Johnson J. Granulosa cell and oocyte mitochondrial abnormalities in a mouse model of fragile X primary ovarian insufficiency. Mol Hum Reprod 2016; 22:384-96. [PMID: 26965313 DOI: 10.1093/molehr/gaw023] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 03/04/2016] [Indexed: 11/13/2022] Open
Abstract
STUDY HYPOTHESIS We hypothesized that the mitochondria of granulosa cells (GC) and/or oocytes might be abnormal in a mouse model of fragile X premutation (FXPM). STUDY FINDING Mice heterozygous and homozygous for the FXPM have increased death (atresia) of large ovarian follicles, fewer corpora lutea with a gene dosage effect manifesting in decreased litter size(s). Furthermore, granulosa cells (GC) and oocytes of FXPM mice have decreased mitochondrial content, structurally abnormal mitochondria, and reduced expression of critical mitochondrial genes. Because this mouse allele produces the mutant Fragile X mental retardation 1 (Fmr1) transcript and reduced levels of wild-type (WT) Fmr1 protein (FMRP), but does not produce a Repeat Associated Non-ATG Translation (RAN)-translation product, our data lend support to the idea that Fmr1 mRNA with large numbers of CGG-repeats is intrinsically deleterious in the ovary. WHAT IS KNOWN ALREADY Mitochondrial dysfunction has been detected in somatic cells of human and mouse FX PM carriers and mitochondria are essential for oogenesis and ovarian follicle development, FX-associated primary ovarian insufficiency (FXPOI) is seen in women with FXPM alleles. These alleles have 55-200 CGG repeats in the 5' UTR of an X-linked gene known as FMR1. The molecular basis of the pathology seen in this disorder is unclear but is thought to involve either some deleterious consequence of overexpression of RNA with long CGG-repeat tracts or of the generation of a repeat-associated non-AUG translation (RAN translation) product that is toxic. STUDY DESIGN, SAMPLES/MATERIALS, METHODS Analysis of ovarian function in a knock-in FXPM mouse model carrying 130 CGG repeats was performed as follows on WT, PM/+, and PM/PM genotypes. Histomorphometric assessment of follicle and corpora lutea numbers in ovaries from 8-month-old mice was executed, along with litter size analysis. Mitochondrial DNA copy number was quantified in oocytes and GC using quantitative PCR, and cumulus granulosa mitochondrial content was measured by flow cytometric analysis after staining of cells with Mitotracker dye. Transmission electron micrographs were prepared of GC within small growing follicles and mitochondrial architecture was compared. Quantitative RT-PCR analysis of key genes involved in mitochondrial structure and recycling was performed. MAIN RESULTS AND THE ROLE OF CHANCE A defect was found in follicle survival at the large antral stage in PM/+ and PM/PM mice. Litter size was significantly decreased in PM/PM mice, and corpora lutea were significantly reduced in mice of both mutant genotypes. Mitochondrial DNA copy number was significantly decreased in GC and metaphase II eggs in mutants. Flow cytometric analysis revealed that PM/+ and PM/PM animals lack the cumulus GC that harbor the greatest mitochondrial content as found in wild-type animals. Electron microscopic evaluation of GC of small growing follicles revealed mitochondrial structural abnormalities, including disorganized and vacuolar cristae. Finally, aberrant mitochondrial gene expression was detected. Mitofusin 2 (Mfn2) and Optic atrophy 1 (Opa1), genes involved in mitochondrial fusion and structure, respectively, were significantly decreased in whole ovaries of both mutant genotypes. Mitochondrial fission factor 1 (Mff1) was significantly decreased in PM/+ and PM/PM GC and eggs compared with wild-type controls. LIMITATIONS, REASONS FOR CAUTION Data from the mouse model used for these studies should be viewed with some caution when considering parallels to the human FXPOI condition. WIDER IMPLICATIONS OF THE FINDINGS Our data lend support to the idea that Fmr1 mRNA with large numbers of CGG-repeats is intrinsically deleterious in the ovary. FXPM disease states, including FXPOI, may share mitochondrial dysfunction as a common underlying mechanism. LARGE SCALE DATA Not applicable. STUDY FUNDING AND COMPETING INTERESTS Studies were supported by NIH R21 071873 (J.J./G.H), The Albert McKern Fund for Perinatal Research (J.J.), NIH Intramural Funds (K.U.), and a TUBITAK Research Fellowship Award (B.U.). No conflict(s) of interest or competing interest(s) are noted.
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Affiliation(s)
- Carola Conca Dioguardi
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, CT, USA Vita-Salute San Raffaele University/IRCCS San Raffaele Hospital, Milan, Italy
| | - Bahar Uslu
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, CT, USA
| | - Monique Haynes
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, CT, USA
| | - Meltem Kurus
- Department of Histology & Embryology, Izmir Katip Celebi University School of Medicine, Izmir, Turkey
| | - Mehmet Gul
- Department of Histology & Embryology, Inonu University School of Medicine, Malatya, Turkey
| | - De-Qiang Miao
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, CT, USA
| | - Lucia De Santis
- Department of Obstetrics & Gynecology, IVF Unit, Vita-Salute San Raffaele University/IRCCS San Raffaele Hospital, Milan, Italy
| | - Maurizio Ferrari
- Laboratory of Clinical Molecular Biology and Cytogenetics, Vita-Salute San Raffaele University/IRCCS San Raffaele Hospital, Milan, Italy
| | - Stefania Bellone
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Gynecologic Oncology, Yale School of Medicine, New Haven, CT, USA
| | - Alessandro Santin
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Gynecologic Oncology, Yale School of Medicine, New Haven, CT, USA
| | - Cecilia Giulivi
- Department of Molecular Biosciences, M.I.N.D. Institute, University of California-Davis, Davis, CA, USA
| | - Gloria Hoffman
- Department of Biology, Morgan State University, Baltimore, MD, USA
| | - Karen Usdin
- Laboratory of Cellular and Molecular Biology, NIH/NIDDK, Bethesda, MD, USA
| | - Joshua Johnson
- Department of Obstetrics, Gynecology, & Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, CT, USA
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Gerhardt J. Epigenetic modifications in human fragile X pluripotent stem cells; Implications in fragile X syndrome modeling. Brain Res 2015; 1656:55-62. [PMID: 26475977 DOI: 10.1016/j.brainres.2015.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 08/18/2015] [Accepted: 10/02/2015] [Indexed: 12/18/2022]
Abstract
Patients with fragile X syndrome (FXS) exhibit moderate to severe intellectual disabilities. In addition, one-third of FXS patients show characteristics of autism spectrum disorder. FXS is caused by a trinucleotide repeat expansion, which leads to silencing of the fragile X mental retardation (FMR1) gene. The absence of the FMR1 gene product, FMRP, is the reason for the disease symptoms. It has been suggested that repeat instability and transcription of the FMR1 gene occur during early embryonic development, while after cell differentiation repeats become stable and the FMR1 gene is silent. Epigenetic marks, such as DNA methylation, are associated with gene silencing and repeat stability at the FMR1 locus. However, the mechanisms leading to gene silencing and repeat expansion are still ambiguous, because studies at the human genomic locus were limited until now. The FXS pluripotent stem cells, recently derived from FXS adult cells and FXS blastocysts, are new useful tools to examine these mechanisms at the human endogenous FMR1 locus. This review summarizes the epigenetic features and experimental studies of FXS human embryonic and FXS induced pluripotent stem cells, generated so far. This article is part of a Special Issue entitled SI: Exploiting human neurons.
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Affiliation(s)
- Jeannine Gerhardt
- Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx 10461, USA.
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Usdin K, Kumari D. Repeat-mediated epigenetic dysregulation of the FMR1 gene in the fragile X-related disorders. Front Genet 2015; 6:192. [PMID: 26089834 PMCID: PMC4452891 DOI: 10.3389/fgene.2015.00192] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 05/13/2015] [Indexed: 12/13/2022] Open
Abstract
The fragile X-related disorders are members of the Repeat Expansion Diseases, a group of genetic conditions resulting from an expansion in the size of a tandem repeat tract at a specific genetic locus. The repeat responsible for disease pathology in the fragile X-related disorders is CGG/CCG and the repeat tract is located in the 5′ UTR of the FMR1 gene, whose protein product FMRP, is important for the proper translation of dendritic mRNAs in response to synaptic activation. There are two different pathological FMR1 allele classes that are distinguished only by the number of repeats. Premutation alleles have 55–200 repeats and confer risk of fragile X-associated tremor/ataxia syndrome and fragile X-associated primary ovarian insufficiency. Full mutation alleles on the other hand have >200 repeats and result in fragile X syndrome, a disorder that affects learning and behavior. Different symptoms are seen in carriers of premutation and full mutation alleles because the repeat number has paradoxical effects on gene expression: Epigenetic changes increase transcription from premutation alleles and decrease transcription from full mutation alleles. This review will cover what is currently known about the mechanisms responsible for these changes in FMR1 expression and how they may relate to other Repeat Expansion Diseases that also show repeat-mediated changes in gene expression.
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Affiliation(s)
- Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health , Bethesda, MD, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health , Bethesda, MD, USA
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35
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Huang J, Ikeuchi Y, Malumbres M, Bonni A. A Cdh1-APC/FMRP Ubiquitin Signaling Link Drives mGluR-Dependent Synaptic Plasticity in the Mammalian Brain. Neuron 2015; 86:726-39. [PMID: 25913861 DOI: 10.1016/j.neuron.2015.03.049] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 12/09/2014] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
Deregulation of synaptic plasticity may contribute to the pathogenesis of developmental cognitive disorders. In particular, exaggerated mGluR-dependent LTD is featured in fragile X syndrome, but the mechanisms that regulate mGluR-LTD remain incompletely understood. We report that conditional knockout of Cdh1, the key regulatory subunit of the ubiquitin ligase Cdh1-anaphase-promoting complex (Cdh1-APC), profoundly impairs mGluR-LTD in the hippocampus. Mechanistically, we find that Cdh1-APC operates in the cytoplasm to drive mGluR-LTD. We also identify the fragile X syndrome protein FMRP as a substrate of Cdh1-APC. Endogenous Cdh1-APC forms a complex with endogenous FMRP, and knockout of Cdh1 impairs mGluR-induced ubiquitination and degradation of FMRP in the hippocampus. Knockout of FMRP suppresses, and expression of an FMRP mutant protein that fails to interact with Cdh1 phenocopies, the Cdh1 knockout phenotype of impaired mGluR-LTD. These findings define Cdh1-APC and FMRP as components of a novel ubiquitin signaling pathway that regulates mGluR-LTD in the brain.
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Affiliation(s)
- Ju Huang
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Yoshiho Ikeuchi
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Marcos Malumbres
- Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Azad Bonni
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
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Muzar Z, Lozano R, Schneider A, Adams PE, Faradz SMH, Tassone F, Hagerman RJ. Methadone use in a male with the FMRI premutation and FXTAS. Am J Med Genet A 2015; 167:1354-9. [PMID: 25900641 DOI: 10.1002/ajmg.a.37030] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 02/08/2015] [Indexed: 01/18/2023]
Abstract
The fragile X-associated tremor ataxia syndrome (FXTAS) is caused by the premutation in FMR1 gene. Recent reports of environmental toxins appear to worsen the progression of FXTAS. Here we present a case of male adult with FXTAS and a long history of methadone use. The patient shows a faster progression in both symptoms of disease and MRI changes compared to what is typically seen in FXTAS. There has been no research regarding the role of narcotics in onset, progression, and severity of FXTAS symptoms. However, research has shown that narcotics can have a negative impact on several neurodegenerative diseases, and we hypothesize that in this particular case, methadone may have contributed to a faster progression of FXTAS as well as exacerbating white matter disease through RNA toxicity seen in premutation carriers.
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Affiliation(s)
- Zukhrofi Muzar
- Center for Biomedical Research, Faculty of Medicine Diponegoro University Semarang, Central Java, Indonesia.,Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California
| | - Reymundo Lozano
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California.,Department of Pediatrics, UC Davis Medical Center, Sacramento, California
| | - Andrea Schneider
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California.,Department of Pediatrics, UC Davis Medical Center, Sacramento, California
| | - Patrick E Adams
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California.,Department of Pediatrics, UC Davis Medical Center, Sacramento, California
| | - Sultana M H Faradz
- Center for Biomedical Research, Faculty of Medicine Diponegoro University Semarang, Central Java, Indonesia
| | - Flora Tassone
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California.,Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis, Davis, Califonia
| | - Randi J Hagerman
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, University of California Davis Medical Center, Sacramento, California.,Department of Pediatrics, UC Davis Medical Center, Sacramento, California
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Abstract
Long noncoding RNAs are becoming increasingly appreciated as major players in gene regulation. They have been reported to play diverse roles in many biological processes. Here, we discuss their discovery, features, and known functions in cells. While not comprehensive, this chapter should serve to illustrate the power and promise of studying long noncoding RNAs.
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Pretto DI, Eid JS, Yrigollen CM, Tang HT, Loomis EW, Raske C, Durbin-Johnson B, Hagerman PJ, Tassone F. Differential increases of specific FMR1 mRNA isoforms in premutation carriers. J Med Genet 2014; 52:42-52. [PMID: 25358671 DOI: 10.1136/jmedgenet-2014-102593] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Over 40% of male and ∼16% of female carriers of a premutation FMR1 allele (55-200 CGG repeats) will develop fragile X-associated tremor/ataxia syndrome, an adult onset neurodegenerative disorder, while about 20% of female carriers will develop fragile X-associated primary ovarian insufficiency. Marked elevation in FMR1 mRNA transcript levels has been observed with premutation alleles, and RNA toxicity due to increased mRNA levels is the leading molecular mechanism proposed for these disorders. However, although the FMR1 gene undergoes alternative splicing, it is unknown whether all or only some of the isoforms are overexpressed in premutation carriers and which isoforms may contribute to the premutation pathology. METHODS To address this question, we have applied a long-read sequencing approach using single-molecule real-time (SMRT) sequencing and qRT-PCR. RESULTS Our SMRT sequencing analysis performed on peripheral blood mononuclear cells, fibroblasts and brain tissue samples derived from premutation carriers and controls revealed the existence of 16 isoforms of 24 predicted variants. Although the relative abundance of all mRNA isoforms was significantly increased in the premutation group, as expected based on the bulk increase in mRNA levels, there was a disproportionate (fourfold to sixfold) increase, relative to the overall increase in mRNA, in the abundance of isoforms spliced at both exons 12 and 14, specifically Iso10 and Iso10b, containing the complete exon 15 and differing only in splicing in exon 17. CONCLUSIONS These findings suggest that RNA toxicity may arise from a relative increase of all FMR1 mRNA isoforms. Interestingly, the Iso10 and Iso10b mRNA isoforms, lacking the C-terminal functional sites for fragile X mental retardation protein function, are the most increased in premutation carriers relative to normal, suggesting a functional relevance in the pathology of FMR1-associated disorders.
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Affiliation(s)
- Dalyir I Pretto
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - John S Eid
- Pacific Biosciences, Menlo Park, California, USA
| | - Carolyn M Yrigollen
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Hiu-Tung Tang
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Erick W Loomis
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Chris Raske
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA
| | - Blythe Durbin-Johnson
- Department of Public Health Sciences, University of California Davis, School of Medicine, Davis, California, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA MIND Institute, University of California Davis Medical Center, Sacramento, California, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California, School of Medicine, Davis, California, USA MIND Institute, University of California Davis Medical Center, Sacramento, California, USA
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Renoux AJ, Carducci NM, Ahmady AA, Todd PK. Fragile X mental retardation protein expression in Alzheimer's disease. Front Genet 2014; 5:360. [PMID: 25452762 PMCID: PMC4233940 DOI: 10.3389/fgene.2014.00360] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 09/27/2014] [Indexed: 12/31/2022] Open
Abstract
The FMR1 protein product, FMRP, is an mRNA binding protein associated with translational inhibition of target transcripts. One FMRP target is the amyloid precursor protein (APP) mRNA, and APP levels are elevated in Fmr1 KO mice. Given that elevated APP protein expression can elicit Alzheimer's disease (AD) in patients and model systems, we evaluated whether FMRP expression might be altered in Alzheimer's autopsy brain samples and mouse models compared to controls. In a double transgenic mouse model of AD (APP/PS1), we found no difference in FMRP expression in aged AD model mice compared to littermate controls. FMRP expression was also similar in AD and control patient frontal cortex and cerebellum samples. Fragile X-associated tremor/ataxia syndrome (FXTAS) is an age-related neurodegenerative disorder caused by expanded CGG repeats in the 5' untranslated region of the FMR1 gene. Patients experience cognitive impairment and dementia in addition to motor symptoms. In parallel studies, we measured FMRP expression in cortex and cerebellum from three FXTAS patients and found reduced expression compared to both controls and Alzheimer's patient brains, consistent with animal models. We also find increased APP levels in cerebellar, but not cortical, samples of FXTAS patients compared to controls. Taken together, these data suggest that a decrease in FMRP expression is unlikely to be a primary contributor to Alzheimer's disease pathogenesis.
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Affiliation(s)
- Abigail J Renoux
- Department of Molecular and Integrative Physiology, University of Michigan , Ann Arbor, MI, USA ; Department of Neurology, University of Michigan , Ann Arbor, MI, USA
| | | | - Arya A Ahmady
- Department of Neurology, University of Michigan , Ann Arbor, MI, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan , Ann Arbor, MI, USA
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Pretto D, Yrigollen CM, Tang HT, Williamson J, Espinal G, Iwahashi CK, Durbin-Johnson B, Hagerman RJ, Hagerman PJ, Tassone F. Clinical and molecular implications of mosaicism in FMR1 full mutations. Front Genet 2014; 5:318. [PMID: 25278957 PMCID: PMC4166380 DOI: 10.3389/fgene.2014.00318] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/25/2014] [Indexed: 12/27/2022] Open
Abstract
Expansions of more than 200 CGG repeats (full mutation) in the FMR1 gene give rise to fragile X syndrome (FXS) through a process that generally involves hypermethylation of the FMR1 promoter region and gene silencing, resulting in absence of expression of the encoded protein, FMRP. However, mosaicism with alleles differing in size and extent of methylation often exist within or between tissues of individuals with FXS. In the current work, CGG-repeat lengths and methylation status were assessed for eighteen individuals with FXS, including 13 mosaics, for which peripheral blood cells (PBMCs) and primary fibroblast cells were available. Our results show that for both PBMCs and fibroblasts, FMR1 mRNA and FMRP expression are directly correlated with the percent of methylation of the FMR1 allele. In addition, Full Scale IQ scores were inversely correlated with the percent methylation and positively correlated with higher FMRP expression. These latter results point toward a positive impact on cognition for full mutation mosaics with lower methylation compared to individuals with fully methylated, full mutation alleles. However, we did not observe a significant reduction in the number of seizures, nor in the severity of hyperactivity or autism spectrum disorder, among individuals with mosaic genotypes in the presentation of FXS. These observations suggest that low, but non-zero expression of FMRP may be sufficient to positively impact cognitive function in individuals with FXS, with methylation mosaicism (lowered methylation fraction) contributing to a more positive clinical outcome.
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Affiliation(s)
- Dalyir Pretto
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - Carolyn M Yrigollen
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - Hiu-Tung Tang
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - John Williamson
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - Glenda Espinal
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - Chris K Iwahashi
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA
| | - Blythe Durbin-Johnson
- Department of Public Health Sciences, School of Medicine, University of California at Davis Davis, CA, USA
| | - Randi J Hagerman
- Department of Pediatrics, School of Medicine, University of California at Davis Davis, CA, USA ; MIND Institute, UC Davis Medical Center Sacramento, CA, USA
| | - Paul J Hagerman
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA ; Department of Pediatrics, School of Medicine, University of California at Davis Davis, CA, USA
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California at Davis Davis, CA, USA ; Department of Pediatrics, School of Medicine, University of California at Davis Davis, CA, USA
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Biancalana V, Glaeser D, McQuaid S, Steinbach P. EMQN best practice guidelines for the molecular genetic testing and reporting of fragile X syndrome and other fragile X-associated disorders. Eur J Hum Genet 2014; 23:417-25. [PMID: 25227148 PMCID: PMC4666582 DOI: 10.1038/ejhg.2014.185] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 07/09/2014] [Accepted: 07/10/2014] [Indexed: 01/25/2023] Open
Abstract
Different mutations occurring in the unstable CGG repeat in 5' untranslated region of FMR1 gene are responsible for three fragile X-associated disorders. An expansion of over ∼200 CGG repeats when associated with abnormal methylation and inactivation of the promoter is the mutation termed ‘full mutation' and is responsible for fragile X syndrome (FXS), a neurodevelopmental disorder described as the most common cause of inherited intellectual impairment. The term ‘abnormal methylation' is used here to distinguish the DNA methylation induced by the expanded repeat from the ‘normal methylation' occurring on the inactive X chromosomes in females with normal, premutation, and full mutation alleles. All male and roughly half of the female full mutation carriers have FXS. Another anomaly termed ‘premutation' is characterized by the presence of 55 to ∼200 CGGs without abnormal methylation, and is the cause of two other diseases with incomplete penetrance. One is fragile X-associated primary ovarian insufficiency (FXPOI), which is characterized by a large spectrum of ovarian dysfunction phenotypes and possible early menopause as the end stage. The other is fragile X-associated tremor/ataxia syndrome (FXTAS), which is a late onset neurodegenerative disorder affecting males and females. Because of the particular pattern and transmission of the CGG repeat, appropriate molecular testing and reporting is very important for the optimal genetic counselling in the three fragile X-associated disorders. Here, we describe best practice guidelines for genetic analysis and reporting in FXS, FXPOI, and FXTAS, including carrier and prenatal testing.
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Affiliation(s)
- Valérie Biancalana
- Laboratoire Diagnostic Génétique, Faculté de Médecine-CHRU, Strasbourg, France
| | | | - Shirley McQuaid
- National Centre for Medical Genetics, Our Lady's Children's Hospital, Crumlin, Dublin, Ireland
| | - Peter Steinbach
- Institute of Human Genetics, University Hospital of Ulm, Ulm, Germany
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Don't miss patients with atypical FMR1 mutations: dysmorphism and clinical features in a boy with a partially methylated FMR1 full mutation. Eur J Pediatr 2014; 173:1257-61. [PMID: 25027833 DOI: 10.1007/s00431-014-2375-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 06/27/2014] [Accepted: 06/27/2014] [Indexed: 10/25/2022]
Abstract
UNLABELLED Fragile X syndrome characterized by intellectual disability (ID), facial dysmorphism, and postpubertal macroorchidism is the most common monogenic cause of ID. It is typically induced by an expansion of a CGG repeat in the fragile X mental retardation 1 (FMR1) gene on Xq27 to more than 200 repeats. Only rarely patients have atypical mutations in the FMR1 gene such as point mutations, deletions, or unmethylated/partially methylated full mutations. Most of these patients show a minor phenotype or even appear clinically healthy. Here, we report the dysmorphism and clinical features of a 17-year-old boy with a partially methylated full mutation of approximately 250 repeats. Diagnosis was made subsequently to the evaluation of a FMR1 premutation as the cause for maternal premature ovarian failure. Dysmorphic evaluation revealed no strikingly long face, no prominent forehead/frontal bossing, no prominent mandible, no macroorchidism, and a head circumference in the lower normal range. Acquisition of a driving license for mopeds and unaccompanied rides by public transport in his home province indicate rather mild ID (IQ = 58). CONCLUSION This adolescent demonstrates that apart from only minor ID, patients with a partially methylated FMR1 full mutation present less to absent pathognomonic facial dysmorphism, thus emphasizing the impact of family history for a straightforward clinical diagnosis.
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Hall DA, Birch RC, Anheim M, Jønch AE, Pintado E, O'Keefe J, Trollor JN, Stebbins GT, Hagerman RJ, Fahn S, Berry-Kravis E, Leehey MA. Emerging topics in FXTAS. J Neurodev Disord 2014; 6:31. [PMID: 25642984 PMCID: PMC4141265 DOI: 10.1186/1866-1955-6-31] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 04/23/2014] [Indexed: 02/07/2023] Open
Abstract
This paper summarizes key emerging issues in fragile X-associated tremor/ataxia syndrome (FXTAS) as presented at the First International Conference on the FMR1 Premutation: Basic Mechanisms & Clinical Involvement in 2013.
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Affiliation(s)
- Deborah A Hall
- Department of Neurological Sciences, Rush University, Chicago, IL, USA
| | - Rachael C Birch
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, Australia
| | - Mathieu Anheim
- Département de Neurologie, Hôpitaux Universitaires de Strasbourg, Hôpital de Hautepierre, 67098 Strasbourg, Cedex, France ; Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM-U964/CNRS-UMR7104/Université de Strasbourg, 67404 Illkirch, France ; Fédération de Médecine Translationnelle de Strasbourg (FMTS), Université de Strasbourg, Strasbourg, France
| | - Aia E Jønch
- Department of clinical Genetics, Kennedy Center, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Elizabeth Pintado
- Department of Medical Biochemistry and Molecular Biology, University of Seville, Sevilla, Spain
| | - Joanne O'Keefe
- Department of Anatomy & Cell Biology, Rush University, Chicago, IL, USA
| | - Julian N Trollor
- Department of Developmental Disability Neuropsychiatry, School of Psychiatry, University of New South Wales, Sydney, Australia ; Centre for Healthy Brain Ageing, University of New South Wales, Sydney, Australia
| | - Glenn T Stebbins
- Department of Neurological Sciences, Rush University, Chicago, IL, USA
| | - Randi J Hagerman
- Department of Pediatrics & M.I.N.D. Institute, University of California at Davis Medical Center, Sacramento, CA, USA
| | - Stanley Fahn
- Department of Neurology, Columbia University, New York, NY, USA
| | - Elizabeth Berry-Kravis
- Department of Neurological Sciences, Rush University, Chicago, IL, USA ; Departments of Pediatrics and Biochemistry, Rush University, Chicago, IL, USA
| | - Maureen A Leehey
- Department of Neurology, University of Colorado at Denver, Denver, CO, USA
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Usdin K, Hayward BE, Kumari D, Lokanga RA, Sciascia N, Zhao XN. Repeat-mediated genetic and epigenetic changes at the FMR1 locus in the Fragile X-related disorders. Front Genet 2014; 5:226. [PMID: 25101111 PMCID: PMC4101883 DOI: 10.3389/fgene.2014.00226] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 06/29/2014] [Indexed: 01/01/2023] Open
Abstract
The Fragile X-related disorders are a group of genetic conditions that include the neurodegenerative disorder, Fragile X-associated tremor/ataxia syndrome (FXTAS), the fertility disorder, Fragile X-associated primary ovarian insufficiency (FXPOI) and the intellectual disability, Fragile X syndrome (FXS). The pathology in all these diseases is related to the number of CGG/CCG-repeats in the 5′ UTR of the Fragile X mental retardation 1 (FMR1) gene. The repeats are prone to continuous expansion and the increase in repeat number has paradoxical effects on gene expression increasing transcription on mid-sized alleles and decreasing it on longer ones. In some cases the repeats can simultaneously both increase FMR1 mRNA production and decrease the levels of the FMR1 gene product, Fragile X mental retardation 1 protein (FMRP). Since FXTAS and FXPOI result from the deleterious consequences of the expression of elevated levels of FMR1 mRNA and FXS is caused by an FMRP deficiency, the clinical picture is turning out to be more complex than once appreciated. Added complications result from the fact that increasing repeat numbers make the alleles somatically unstable. Thus many individuals have a complex mixture of different sized alleles in different cells. Furthermore, it has become apparent that the eponymous fragile site, once thought to be no more than a useful diagnostic criterion, may have clinical consequences for females who inherit chromosomes that express this site. This review will cover what is currently known about the mechanisms responsible for repeat instability, for the repeat-mediated epigenetic changes that affect expression of the FMR1 gene, and for chromosome fragility. It will also touch on what current and future options are for ameliorating some of these effects.
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Affiliation(s)
- Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Bruce E Hayward
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Rachel A Lokanga
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Nicholas Sciascia
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
| | - Xiao-Nan Zhao
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda MD, USA
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Tonnsen B, Cornish KM, Wheeler AC, Roberts JE. Maternal predictors of anxiety risk in young males with fragile X. Am J Med Genet B Neuropsychiatr Genet 2014; 165B:399-409. [PMID: 24832235 PMCID: PMC4681279 DOI: 10.1002/ajmg.b.32244] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/23/2014] [Indexed: 12/11/2022]
Abstract
Children with fragile X syndrome (FXS) demonstrate high rates of anxiety disorders, with 65-83% meeting diagnostic criteria. The severity of anxiety symptoms in FXS has been shown to be partially predicted by elevated negative affect across early childhood [Tonnsen et al. (2013a); J Abnorm Child Psychol 41:267-280]. This association suggests that biologically driven vulnerability emerges early in development, as is reported in non-clinical populations. However, anxiety emergence is likely moderated by multifaceted genetic, biological and environmental risk and protective factors. Mothers with the FMR1 premutation have been shown to exhibit elevated parenting stress and internalizing symptoms, which have each been associated with child behavior problems [Bailey et al. (2008a); Am J Med Genet Part A 146A:2060-2069 and Bailey et al. (2008b) Am J Med Genet Part A 146A:720-729]. Despite these findings, it is unclear whether maternal factors directly relate to anxiety vulnerability in high-risk children with FXS, a question essential to informing targeted, family-sensitive treatment. The present study examines how maternal protective and risk factors relate to child inhibition reflected in (1) child anxiety symptoms, (2) child trajectories of negative affect, and (3) the association between child anxiety and negative affect. Primary predictors include maternal parenting stress, indicators of mental health risk (anxiety and depressive symptoms), and maternal optimism. We also examine genetic correlates in mothers (CGG repeats, activation ratio, mRNA). Our findings suggest that behavioral inhibition in young children with FXS is associated with higher parenting stress and lower optimism, and higher parenting stress is associated with lower maternal X-activation ratio. These findings underscore the need for family-sensitive treatment strategies for anxiety disorders in children with FXS.
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Affiliation(s)
- Bridgette Tonnsen
- Department of Psychology, University of South Carolina, Columbia, South Carolina
| | - Kim M. Cornish
- School of Psychological Sciences, Monash University, Melbourne, Australia
| | | | - Jane E. Roberts
- Department of Psychology, University of South Carolina, Columbia, South Carolina
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Inaba Y, Schwartz CE, Bui QM, Li X, Skinner C, Field M, Wotton T, Hagerman RJ, Francis D, Amor DJ, Hopper JL, Loesch DZ, Bretherton L, Slater HR, Godler DE. Early Detection of Fragile X Syndrome: Applications of a Novel Approach for Improved Quantitative Methylation Analysis in Venous Blood and Newborn Blood Spots. Clin Chem 2014; 60:963-73. [DOI: 10.1373/clinchem.2013.217331] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
BACKGROUND
Standard fragile X syndrome (FXS) diagnostic tests that target methylation of the fragile X mental retardation 1 (FMR1) CpG island 5′ of the CGG expansion can be used to predict severity of the disease in males from birth, but not in females.
METHODS
We describe methylation specific–quantitative melt analysis (MS-QMA) that targets 10 CpG sites, with 9 within FMR1 intron 1, to screen for FXS from birth in both sexes. The novel method combines the qualitative strengths of high-resolution melt and the high-throughput, quantitative real-time PCR standard curve to provide accurate quantification of DNA methylation in a single assay. Its performance was assessed in 312 control (CGG <40), 143 premutation (PM) (CGG 56–170), 197 full mutation (FM) (CGG 200–2000), and 33 CGG size and methylation mosaic samples.
RESULTS
In male and female newborn blood spots, MS-QMA differentiated FM from control alleles, with sensitivity, specificity, and positive and negative predictive values between 92% and 100%. In venous blood of FM females between 6 and 35 years of age, MS-QMA correlated most strongly with verbal IQ impairment (P = 0.002). In the larger cohort of males and females, MS-QMA correlated with reference methods Southern blot and MALDI-TOF mass spectrometry (P < 0.05), but was not significantly correlated with age. Unmethylated alleles in high-functioning FM and PM males determined by both reference methods were also unmethylated by MS-QMA.
CONCLUSIONS
MS-QMA has an immediate application in FXS diagnostics, with a potential use of its quantitative methylation output for prognosis in both sexes.
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Affiliation(s)
- Yoshimi Inaba
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Charles E Schwartz
- Center for Molecular Studies, J.C. Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, SC
| | - Quang M Bui
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne, Carlton, Victoria, Australia
| | - Xin Li
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Cindy Skinner
- Center for Molecular Studies, J.C. Self Research Institute of Human Genetics, Greenwood Genetic Center, Greenwood, SC
| | - Michael Field
- Genetics of Learning Disability Service, New South Wales, Australia
| | - Tiffany Wotton
- New South Wales Newborn Screening Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Randi J Hagerman
- The MIND Institute, University of California, Davis Medical Center, Sacramento, CA
- Department of Pediatrics, University of California, Davis School of Medicine, Sacramento, CA
| | - David Francis
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - David J Amor
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne Victoria, Australia
| | - John L Hopper
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne, Carlton, Victoria, Australia
| | - Danuta Z Loesch
- School of Psychological Science, La Trobe University, Melbourne, Victoria, Australia
| | - Lesley Bretherton
- Department of Paediatrics, University of Melbourne, Melbourne Victoria, Australia
- Melbourne School of Psychological Sciences, University of Melbourne; Melbourne Victoria, Australia
- Department of Clinical Psychology, The Royal Children's Hospital, Melbourne; Victoria, Australia
| | - Howard R Slater
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Melbourne Victoria, Australia
| | - David E Godler
- Cyto-molecular Diagnostic Research Laboratory, Victorian Clinical Genetics Services and Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
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Chaudhary AG, Hussein IR, Abuzenadah A, Gari M, Bassiouni R, Sogaty S, Lary S, Al-Quaiti M, Al Balwi M, Al Qahtani M. Molecular diagnosis of fragile X syndrome using methylation sensitive techniques in a cohort of patients with intellectual disability. Pediatr Neurol 2014; 50:368-76. [PMID: 24630283 DOI: 10.1016/j.pediatrneurol.2013.11.020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/04/2013] [Accepted: 11/23/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Fragile X syndrome, the most common form of inherited intellectual disability, is caused by expansion of CGG trinucleotide repeat at the 5' untranslated region of the FMR1 gene at Xq27. In affected individuals, the CGG repeat expansion leads to hypermethylation and the gene is transcriptionally inactive. Our aim was to identify fragile X syndrome among children with intellectual disability in Saudi Arabia. PATIENTS AND METHODS The study included 63 patients (53 males, 10 females) presented with intellectual disability, 29 normal subjects, and 23 other family members. DNA samples from six patients previously diagnosed with fragile X syndrome by Southern blot technique were used as positive controls. The method was based on bisulfite treatment of DNA followed by two different techniques. The first technique applied polymerase chain reaction amplification using one set of primers specific for amplifying methylated CpG dinucleotide region; another set designed to amplify the unmethylated CGG repeats. The second technique used the methylation-specific melting curve analysis for detection of methylation status of the FMR1 promoter region. RESULTS Molecular testing using methylation sensitive polymerase chain reaction had shown amplified products in all normal subjects using unmethylated but not methylated primers indicating normal alleles, whereas amplified products were obtained using methylated polymerase chain reaction primers in fragile X syndrome-positive samples and in 9 of 53 males, indicating affected individuals. Molecular testing using melting curve analysis has shown a single low melting peak in all normal males and in (44/53) patients indicating unmethylated FMR1 gene, whereas high melting peak indicating methylated gene was observed in the fragile X syndrome-positive samples and in 9 of 53 patients. We found 100% concordance between results of both techniques and the results of Southern blot analysis. Three samples have shown both methylated and unmethylated alleles, indicating possible mosaicism. No female patients or carriers could be detected by both techniques. CONCLUSION The technique can be applied for the rapid screening for fragile X syndrome among patients with intellectual disability. The impact of mosaicism on clinical severity needs further investigation.
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Affiliation(s)
- Adeel G Chaudhary
- Faculty of Medical Sciences, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Ibtessam R Hussein
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
| | - Adel Abuzenadah
- Faculty of Medical Sciences, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Mamdouh Gari
- Faculty of Medical Sciences, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Randa Bassiouni
- Pediatric Hospital, Ministry of Health, Al Taif, Kingdom of Saudi Arabia
| | | | - Sahira Lary
- Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Maha Al-Quaiti
- Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Mohammed Al Balwi
- King Abdulaziz Medical City for National Guard Health Affairs, and King Saud bin Abdulaziz University for Health Sciences, Riyadh, Kingdom of Saudi Arabia
| | - Mohammed Al Qahtani
- Faculty of Medical Sciences, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
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Pretto DI, Mendoza-Morales G, Lo J, Cao R, Hadd A, Latham GJ, Durbin-Johnson B, Hagerman R, Tassone F. CGG allele size somatic mosaicism and methylation in FMR1 premutation alleles. J Med Genet 2014; 51:309-18. [PMID: 24591415 DOI: 10.1136/jmedgenet-2013-102021] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Greater than 200 CGG repeats in the 5'UTR of the FMR1 gene lead to epigenetic silencing and lack of the FMR1 protein, causing fragile X Syndrome. Individual carriers of a premutation (PM) allele with 55-200 CGG repeats are typically unmethylated and can present with clinical features defined as FMR1-associated conditions. METHODS Blood samples from 17 male PM carriers were assessed clinically and molecularly by Southern blot, western blot, PCR and QRT-PCR. Blood and brain tissue from an additional 18 PM males were also similarly examined. Continuous outcomes were modelled using linear regression and binary outcomes were modelled using logistic regression. RESULTS Methylated alleles were detected in different fractions of blood cells in all PM cases (n=17). CGG repeat numbers correlated with percent of methylation and mRNA levels and, especially in the upper PM range, with greater number of clinical involvements. Inter-tissue/intra-tissue somatic instability and differences in percent methylation were observed between blood and fibroblasts (n=4) and also observed between blood and different brain regions in three of the 18 PM cases examined. CGG repeat lengths in lymphocytes remained unchanged over a period of time ranging from 2 to 6 years, three cases for whom multiple samples were available. CONCLUSIONS In addition to CGG size instability, individuals with a PM expanded allele can exhibit methylation and display more clinical features likely due to RNA toxicity and/or FMR1 silencing. The observed association between CGG repeat length and percent of methylation with the severity of the clinical phenotypes underscores the potential value of methylation in affected PM to further understand penetrance, inform diagnosis and expand treatment options.
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Affiliation(s)
- Dalyir I Pretto
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, Sacramento, California, USA
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Milá M, Ramos F, Tejada MI. Guía clínica de las enfermedades asociadas al gen FMR1: síndrome X frágil, insuficiencia ovárica primaria y síndrome de temblor-ataxia. Med Clin (Barc) 2014; 142:219-25. [DOI: 10.1016/j.medcli.2013.05.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 05/21/2013] [Accepted: 05/23/2013] [Indexed: 12/14/2022]
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Fragile X syndrome: a preclinical review on metabotropic glutamate receptor 5 (mGluR5) antagonists and drug development. Psychopharmacology (Berl) 2014; 231:1217-26. [PMID: 24232444 DOI: 10.1007/s00213-013-3330-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
RATIONALE Fragile X syndrome (FXS) is considered the leading inherited cause of intellectual disability and autism. In FXS, the fragile X mental retardation 1 (FMR1) gene is silenced and the fragile X mental retardation protein (FMRP) is not expressed, resulting in the characteristic features of the syndrome. Despite recent advances in understanding the pathophysiology of FXS, there is still no cure for this condition; current treatment is symptomatic. Preclinical research is essential in the development of potential therapeutic agents. OBJECTIVES This review provides an overview of the preclinical evidence supporting metabotropic glutamate receptor 5 (mGluR5) antagonists as therapeutic agents for FXS. RESULTS According to the mGluR theory of FXS, the absence of FMRP leads to enhanced glutamatergic signaling via mGluR5, which leads to increased protein synthesis and defects in synaptic plasticity including enhanced long-term depression. As such, efforts to develop agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. Animal models, particularly the Fmr1 knockout mouse model, have become invaluable in exploring therapeutic approaches on an electrophysiological, behavioral, biochemical, and neuroanatomical level. Two direct approaches are currently being investigated for FXS treatment: reactivating the FMR1 gene and compensating for the lack of FMRP. The latter approach has yielded promising results, with mGluR5 antagonists showing efficacy in clinical trials. CONCLUSIONS Targeting mGluR5 is a valid approach for the development of therapeutic agents that target the underlying pathophysiology of FXS. Several compounds are currently in development, with encouraging results.
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