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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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Shah S, Sharp KJ, Raju Ponny S, Lee J, Watts JK, Berry-Kravis E, Richter JD. Antisense oligonucleotide rescue of CGG expansion-dependent FMR1 mis-splicing in fragile X syndrome restores FMRP. Proc Natl Acad Sci U S A 2023; 120:e2302534120. [PMID: 37364131 PMCID: PMC10319035 DOI: 10.1073/pnas.2302534120] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 05/26/2023] [Indexed: 06/28/2023] Open
Abstract
Aberrant alternative splicing of mRNAs results in dysregulated gene expression in multiple neurological disorders. Here, we show that hundreds of mRNAs are incorrectly expressed and spliced in white blood cells and brain tissues of individuals with fragile X syndrome (FXS). Surprisingly, the FMR1 (Fragile X Messenger Ribonucleoprotein 1) gene is transcribed in >70% of the FXS tissues. In all FMR1-expressing FXS tissues, FMR1 RNA itself is mis-spliced in a CGG expansion-dependent manner to generate the little-known FMR1-217 RNA isoform, which is comprised of FMR1 exon 1 and a pseudo-exon in intron 1. FMR1-217 is also expressed in FXS premutation carrier-derived skin fibroblasts and brain tissues. We show that in cells aberrantly expressing mis-spliced FMR1, antisense oligonucleotide (ASO) treatment reduces FMR1-217, rescues full-length FMR1 RNA, and restores FMRP (Fragile X Messenger RibonucleoProtein) to normal levels. Notably, FMR1 gene reactivation in transcriptionally silent FXS cells using 5-aza-2'-deoxycytidine (5-AzadC), which prevents DNA methylation, increases FMR1-217 RNA levels but not FMRP. ASO treatment of cells prior to 5-AzadC application rescues full-length FMR1 expression and restores FMRP. These findings indicate that misregulated RNA-processing events in blood could serve as potent biomarkers for FXS and that in those individuals expressing FMR1-217, ASO treatment may offer a therapeutic approach to mitigate the disorder.
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Affiliation(s)
- Sneha Shah
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA01605
| | - Kevin J. Sharp
- Department of Pediatrics, Rush University Medical Center, Chicago, IL60612
| | - Sithara Raju Ponny
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA01605
| | - Jonathan Lee
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA01605
| | - Jonathan K. Watts
- RNA Therapeutics Institute, University of Massachusetts Chan Medical School, Worcester, MA01605
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA01605
- Li Weibo Rare Disease Institute, University of Massachusetts Chan Medical School, Worcester, MA01605
| | - Elizabeth Berry-Kravis
- Department of Pediatrics, Rush University Medical Center, Chicago, IL60612
- Department of Neurological Sciences, Rush University Medical Center, Chicago, IL60612
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL60612
| | - Joel D. Richter
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA01605
- Li Weibo Rare Disease Institute, University of Massachusetts Chan Medical School, Worcester, MA01605
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Jalnapurkar I, Frazier JA, Roth M, Cochran DM, Foley A, Merk T, Venuti L, Ronco L, Raines S, Cadavid D. The feasibility and utility of hair follicle sampling to measure FMRP and FMR1 mRNA in children with or without fragile X syndrome: a pilot study. J Neurodev Disord 2022; 14:57. [PMID: 36494616 PMCID: PMC9733195 DOI: 10.1186/s11689-022-09465-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 10/26/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability in males and the most common single gene cause of autism. This X-linked disorder is caused by an expansion of a trinucleotide CGG repeat (> 200 base pairs) on the promotor region of the fragile X messenger ribonucleoprotein 1 gene (FMR1). This leads to the deficiency or absence of the encoded protein, fragile X messenger ribonucleoprotein 1 (FMRP). FMRP has a central role in the translation of mRNAs involved in synaptic connections and plasticity. Recent studies have demonstrated the benefit of therapeutics focused on reactivation of the FMR1 locus towards improving key clinical phenotypes via restoration of FMRP and ultimately disease modification. A key step in future studies directed towards this effort is the establishment of proof of concept (POC) for FMRP reactivation in individuals with FXS. For this, it is key to determine the feasibility of repeated collection of tissues or fluids to measure FMR1 mRNA and FMRP. METHODS Individuals, ages 3 to 22 years of age, with FXS and those who were typically developing participated in this single-site pilot clinical biomarker study. The repeated collection of hair follicles was compared with the collection of blood and buccal swabs for detection of FMR1 mRNA and FMRP and related molecules. RESULTS There were n = 15 participants, of whom 10 had a diagnosis of FXS (7.0 ± 3.56 years) and 5 were typically developing (8.2 ± 2.77 years). Absolute levels of FMRP and FMR1 mRNA were substantially higher in healthy participants compared to full mutation and mosaic FXS participants and lowest in the FXS boys. Measurement of FMR1 mRNA and FMRP levels by any method did not show any notable variation by collection location at home versus office across the various sample collection methodologies of hair follicle, blood sample, and buccal swab. CONCLUSION Findings demonstrated that repeated sampling of hair follicles in individuals with FXS, in both, home, and office settings, is feasible, repeatable, and can be used for measurement of FMR1 mRNA and FMRP in longitudinal studies.
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Affiliation(s)
- Isha Jalnapurkar
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Jean A. Frazier
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Mark Roth
- grid.509699.a0000 0004 5907 6392Fulcrum Therapeutics, Cambridge, MA USA
| | - David M. Cochran
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Ann Foley
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Taylor Merk
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Lauren Venuti
- grid.410516.70000 0001 0707 2056Department of Psychiatry, EK Shriver Center, University of Massachusetts Medical School, Worcester, MA USA
| | - Lucienne Ronco
- grid.509699.a0000 0004 5907 6392Fulcrum Therapeutics, Cambridge, MA USA
| | - Shane Raines
- grid.509699.a0000 0004 5907 6392Fulcrum Therapeutics, Cambridge, MA USA
| | - Diego Cadavid
- grid.509699.a0000 0004 5907 6392Fulcrum Therapeutics, Cambridge, MA USA
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Interface of G-quadruplex with both stabilizing and destabilizing ligands for targeting various diseases. Int J Biol Macromol 2022; 219:414-427. [DOI: 10.1016/j.ijbiomac.2022.07.248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/22/2022] [Accepted: 07/29/2022] [Indexed: 11/19/2022]
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Chen Y, Guo L, Han M, Zhang S, Chen Y, Zou J, Bai S, Cheng G, Zeng Y. Cerebellum Neuropathology and Motor Skill Deficits in Fragile X Syndrome. Int J Dev Neurosci 2022; 82:557-568. [DOI: 10.1002/jdn.10217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/11/2022] [Accepted: 07/14/2022] [Indexed: 11/06/2022] Open
Affiliation(s)
- Yu‐shan Chen
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Liu Guo
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Man Han
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Si‐ming Zhang
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Yi‐qi Chen
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Jia Zou
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Shu‐yuan Bai
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Gui‐rong Cheng
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
| | - Yan Zeng
- Brain Science and Advanced Technology Institute, School of Medicine Wuhan University of Science and Technology Wuhan China
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D’Incal C, Broos J, Torfs T, Kooy RF, Vanden Berghe W. Towards Kinase Inhibitor Therapies for Fragile X Syndrome: Tweaking Twists in the Autism Spectrum Kinase Signaling Network. Cells 2022; 11:cells11081325. [PMID: 35456004 PMCID: PMC9029738 DOI: 10.3390/cells11081325] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/01/2022] [Accepted: 04/03/2022] [Indexed: 12/12/2022] Open
Abstract
Absence of the Fragile X Mental Retardation Protein (FMRP) causes autism spectrum disorders and intellectual disability, commonly referred to as the Fragile X syndrome. FMRP is a negative regulator of protein translation and is essential for neuronal development and synapse formation. FMRP is a target for several post-translational modifications (PTMs) such as phosphorylation and methylation, which tightly regulate its cellular functions. Studies have indicated the involvement of FMRP in a multitude of cellular pathways, and an absence of FMRP was shown to affect several neurotransmitter receptors, for example, the GABA receptor and intracellular signaling molecules such as Akt, ERK, mTOR, and GSK3. Interestingly, many of these molecules function as protein kinases or phosphatases and thus are potentially amendable by pharmacological treatment. Several treatments acting on these kinase-phosphatase systems have been shown to be successful in preclinical models; however, they have failed to convincingly show any improvements in clinical trials. In this review, we highlight the different protein kinase and phosphatase studies that have been performed in the Fragile X syndrome. In our opinion, some of the paradoxical study conclusions are potentially due to the lack of insight into integrative kinase signaling networks in the disease. Quantitative proteome analyses have been performed in several models for the FXS to determine global molecular processes in FXS. However, only one phosphoproteomics study has been carried out in Fmr1 knock-out mouse embryonic fibroblasts, and it showed dysfunctional protein kinase and phosphatase signaling hubs in the brain. This suggests that the further use of phosphoproteomics approaches in Fragile X syndrome holds promise for identifying novel targets for kinase inhibitor therapies.
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Affiliation(s)
- Claudio D’Incal
- Protein Chemistry, Proteomics and Epigenetic Signaling (PPES), Department of Biomedical Sciences, University of Antwerp, 2000 Antwerp, Belgium; (C.D.); (J.B.); (T.T.)
- Department of Medical Genetics, University of Antwerp, 2000 Antwerp, Belgium;
| | - Jitse Broos
- Protein Chemistry, Proteomics and Epigenetic Signaling (PPES), Department of Biomedical Sciences, University of Antwerp, 2000 Antwerp, Belgium; (C.D.); (J.B.); (T.T.)
| | - Thierry Torfs
- Protein Chemistry, Proteomics and Epigenetic Signaling (PPES), Department of Biomedical Sciences, University of Antwerp, 2000 Antwerp, Belgium; (C.D.); (J.B.); (T.T.)
| | - R. Frank Kooy
- Department of Medical Genetics, University of Antwerp, 2000 Antwerp, Belgium;
| | - Wim Vanden Berghe
- Protein Chemistry, Proteomics and Epigenetic Signaling (PPES), Department of Biomedical Sciences, University of Antwerp, 2000 Antwerp, Belgium; (C.D.); (J.B.); (T.T.)
- Correspondence: ; Tel.: +0032-(0)-32-652-657
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7
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Rais M, Lovelace JW, Shuai XS, Woodard W, Bishay S, Estrada L, Sharma AR, Nguy A, Kulinich A, Pirbhoy PS, Palacios AR, Nelson DL, Razak KA, Ethell IM. Functional consequences of postnatal interventions in a mouse model of Fragile X syndrome. Neurobiol Dis 2021; 162:105577. [PMID: 34871737 DOI: 10.1016/j.nbd.2021.105577] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/22/2021] [Accepted: 12/02/2021] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Fragile X syndrome (FXS) is a leading genetic cause of autism and intellectual disability with cortical hyperexcitability and sensory hypersensitivity attributed to loss and hypofunction of inhibitory parvalbumin-expressing (PV) cells. Our studies provide novel insights into the role of excitatory neurons in abnormal development of PV cells during a postnatal period of inhibitory circuit refinement. METHODS To achieve Fragile X mental retardation gene (Fmr1) deletion and re-expression in excitatory neurons during the postnatal day (P)14-P21 period, we generated CreCaMKIIa/Fmr1Flox/y (cOFF) and CreCaMKIIa/Fmr1FloxNeo/y (cON) mice, respectively. Cortical phenotypes were evaluated in adult mice using biochemical, cellular, clinically relevant electroencephalogram (EEG) and behavioral tests. RESULTS We found that similar to global Fmr1 KO mice, the density of PV-expressing cells, their activation, and sound-evoked gamma synchronization were impaired in cOFF mice, but the phenotypes were improved in cON mice. cOFF mice also showed enhanced cortical gelatinase activity and baseline EEG gamma power, which were reduced in cON mice. In addition, TrkB phosphorylation and PV levels were lower in cOFF mice, which also showed increased locomotor activity and anxiety-like behaviors. Remarkably, when FMRP levels were restored in only excitatory neurons during the P14-P21 period, TrkB phosphorylation and mouse behaviors were also improved. CONCLUSIONS These results indicate that postnatal deletion or re-expression of FMRP in excitatory neurons is sufficient to elicit or ameliorate structural and functional cortical deficits, and abnormal behaviors in mice, informing future studies about appropriate treatment windows and providing fundamental insights into the cellular mechanisms of cortical circuit dysfunction in FXS.
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Affiliation(s)
- Maham Rais
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Jonathan W Lovelace
- Department of Psychology, University of California Riverside, Riverside, CA 92521, USA
| | - Xinghao S Shuai
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Walker Woodard
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Steven Bishay
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Leo Estrada
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Ashwin R Sharma
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Austin Nguy
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Anna Kulinich
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Patricia S Pirbhoy
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | - Arnold R Palacios
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA
| | | | - Khaleel A Razak
- Department of Psychology, University of California Riverside, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California Riverside, Riverside, CA 92521, USA
| | - Iryna M Ethell
- Division of Biomedical Sciences and Biomedical Sciences Graduate Program, School of Medicine, University of California Riverside, Riverside, CA 92521, USA; Neuroscience Graduate Program, University of California Riverside, Riverside, CA 92521, USA.
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8
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Romagnoli A, Di Marino D. The Use of Peptides in the Treatment of Fragile X Syndrome: Challenges and Opportunities. Front Psychiatry 2021; 12:754485. [PMID: 34803767 PMCID: PMC8599826 DOI: 10.3389/fpsyt.2021.754485] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/11/2021] [Indexed: 01/17/2023] Open
Abstract
Fragile X Syndrome (FXS) is the most frequent cause of inherited intellectual disabilities and autism spectrum disorders, characterized by cognitive deficits and autistic behaviors. The silencing of the Fmr1 gene and consequent lack of FMRP protein, is the major contribution to FXS pathophysiology. FMRP is an RNA binding protein involved in the maturation and plasticity of synapses and its absence culminates in a range of morphological, synaptic and behavioral phenotypes. Currently, there are no approved medications for the treatment of FXS, with the approaches under study being fairly specific and unsatisfying in human trials. Here we propose peptides/peptidomimetics as candidates in the pharmacotherapy of FXS; in the last years this class of molecules has catalyzed the attention of pharmaceutical research, being highly selective and well-tolerated. Thanks to their ability to target protein-protein interactions (PPIs), they are already being tested for a wide range of diseases, including cancer, diabetes, inflammation, Alzheimer's disease, but this approach has never been applied to FXS. As FXS is at the forefront of efforts to develop new drugs and approaches, we discuss opportunities, challenges and potential issues of peptides/peptidomimetics in FXS drug design and development.
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Affiliation(s)
| | - Daniele Di Marino
- Department of Life and Environmental Sciences, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
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9
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Abstract
Neuroepigenetics, a new branch of epigenetics, plays an important role in the regulation of gene expression. Neuroepigenetics is associated with holistic neuronal function and helps in formation and maintenance of memory and learning processes. This includes neurodevelopment and neurodegenerative defects in which histone modification enzymes appear to play a crucial role. These modifications, carried out by acetyltransferases and deacetylases, regulate biologic and cellular processes such as apoptosis and autophagy, inflammatory response, mitochondrial dysfunction, cell-cycle progression and oxidative stress. Alterations in acetylation status of histone as well as non-histone substrates lead to transcriptional deregulation. Histone deacetylase decreases acetylation status and causes transcriptional repression of regulatory genes involved in neural plasticity, synaptogenesis, synaptic and neural plasticity, cognition and memory, and neural differentiation. Transcriptional deactivation in the brain results in development of neurodevelopmental and neurodegenerative disorders. Mounting evidence implicates histone deacetylase inhibitors as potential therapeutic targets to combat neurologic disorders. Recent studies have targeted naturally-occurring biomolecules and micro-RNAs to improve cognitive defects and memory. Multi-target drug ligands targeting HDAC have been developed and used in cell-culture and animal-models of neurologic disorders to ameliorate synaptic and cognitive dysfunction. Herein, we focus on the implications of histone deacetylase enzymes in neuropathology, their regulation of brain function and plausible involvement in the pathogenesis of neurologic defects.
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10
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Reyes ST, Mohajeri S, Krasinska K, Guo SG, Gu M, Pisani L, Rosenberg J, Spielman DM, Chin FT. GABA Measurement in a Neonatal Fragile X Syndrome Mouse Model Using 1H-Magnetic Resonance Spectroscopy and Mass Spectrometry. Front Mol Neurosci 2020; 13:612685. [PMID: 33390902 PMCID: PMC7775297 DOI: 10.3389/fnmol.2020.612685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/20/2020] [Indexed: 11/20/2022] Open
Abstract
Fragile X syndrome (FXS) is the leading monogenetic cause of autism spectrum disorder and inherited cause of intellectual disability that affects approximately one in 7,000 males and one in 11,000 females. In FXS, the Fmr1 gene is silenced and prevents the expression of the fragile X mental retardation protein (FMRP) that directly targets mRNA transcripts of multiple GABAA subunits. Therefore, FMRP loss adversely impacts the neuronal firing of the GABAergic system which creates an imbalance in the excitatory/inhibitory ratio within the brain. Current FXS treatment strategies focus on curing symptoms, such as anxiety or decreased social function. While treating symptoms can be helpful, incorporating non-invasive imaging to evaluate how treatments change the brain's biology may explain what molecular aberrations are associated with disease pathology. Thus, the GABAergic system is suitable to explore developing novel therapeutic strategies for FXS. To understand how the GABAergic system may be affected by this loss-of-function mutation, GABA concentrations were examined within the frontal cortex and thalamus of 5-day-old wild type and Fmr1 knockout mice using both 1H magnetic resonance imaging (1H-MRS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our objective was to develop a reliable scanning method for neonatal mice in vivo and evaluate whether 1H-MRS is suitable to capture regional GABA concentration differences at the front end of the critical cortical period where abnormal neurodevelopment occurs due to FMRP loss is first detected. 1H-MRS quantified GABA concentrations in both frontal cortex and thalamus of wild type and Fmr1 knockout mice. To substantiate the results of our 1H-MRS studies, in vitro LC-MS/MS was also performed on brain homogenates from age-matched mice. We found significant changes in GABA concentration between the frontal cortex and thalamus within each mouse from both wild type and Fmr1 knockout mice using 1H-MRS and LC-MS/MS. Significant GABA levels were also detected in these same regions between wild type and Fmr1 knockout mice by LC-MS/MS, validating that FMRP loss directly affects the GABAergic system. Thus, these new findings support the need to develop an effective non-invasive imaging method to monitor novel GABAergic strategies aimed at treating patients with FXS.
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Affiliation(s)
- Samantha T. Reyes
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Sanaz Mohajeri
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Karolina Krasinska
- Stanford University Mass Spectrometry Laboratory, Stanford University, Stanford, CA, United States
| | - Scarlett G. Guo
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Meng Gu
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Laura Pisani
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Jarrett Rosenberg
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Daniel M. Spielman
- Department of Radiology, Stanford University, Stanford, CA, United States
| | - Frederick T. Chin
- Department of Radiology, Stanford University, Stanford, CA, United States
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11
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Abstract
Over a thousand diseases are caused by mutations that alter gene expression levels. The potential of nuclease-deficient zinc fingers, TALEs or CRISPR fusion systems to treat these diseases by modulating gene expression has recently emerged. These systems can be applied to modify the activity of gene-regulatory elements - promoters, enhancers, silencers and insulators, subsequently changing their target gene expression levels to achieve therapeutic benefits - an approach termed cis-regulation therapy (CRT). Here, we review emerging CRT technologies and assess their therapeutic potential for treating a wide range of diseases caused by abnormal gene dosage. The challenges facing the translation of CRT into the clinic are discussed.
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12
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Majumder M, Johnson RH, Palanisamy V. Fragile X-related protein family: a double-edged sword in neurodevelopmental disorders and cancer. Crit Rev Biochem Mol Biol 2020; 55:409-424. [PMID: 32878499 DOI: 10.1080/10409238.2020.1810621] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The fragile X-related (FXR) family proteins FMRP, FXR1, and FXR2 are RNA binding proteins that play a critical role in RNA metabolism, neuronal plasticity, and muscle development. These proteins share significant homology in their protein domains, which are functionally and structurally similar to each other. FXR family members are known to play an essential role in causing fragile X mental retardation syndrome (FXS), the most common genetic form of autism spectrum disorder. Recent advances in our understanding of this family of proteins have occurred in tandem with discoveries of great importance to neurological disorders and cancer biology via the identification of their novel RNA and protein targets. Herein, we review the FXR family of proteins as they pertain to FXS, other mental illnesses, and cancer. We emphasize recent findings and analyses that suggest contrasting functions of this protein family in FXS and tumorigenesis based on their expression patterns in human tissues. Finally, we discuss current gaps in our knowledge regarding the FXR protein family and their role in FXS and cancer and suggest future studies to facilitate bench to bedside translation of the findings.
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Affiliation(s)
- Mrinmoyee Majumder
- Department of Biochemistry and Molecular Biology, School of Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Roger H Johnson
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
| | - Viswanathan Palanisamy
- Department of Biochemistry and Molecular Biology, School of Medicine, Medical University of South Carolina, Charleston, SC, USA
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13
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Shitik EM, Velmiskina AA, Dolskiy AA, Yudkin DV. Reactivation of FMR1 gene expression is a promising strategy for fragile X syndrome therapy. Gene Ther 2020; 27:247-253. [PMID: 32203197 DOI: 10.1038/s41434-020-0141-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 02/06/2023]
Abstract
Fragile X syndrome (FXS) is the most common form of intellectual disability and autism spectrum disorder and is caused by CGG repeat expansion in the promoter region of the FMR1 gene, which encodes fragile X mental retardation protein. This event leads to gene silencing and the loss of gene products through DNA methylation and chromatin remodeling. Due to the pathogenesis of FXS, targeted, symptomatic, and etiological approaches have been developed for its treatment. Despite their rapid development, symptomatic and targeted treatment approaches have numerous limitations; etiological approaches have the greatest potential because they affect the main causes of transcriptional silencing. In this review, we consider three potential etiological therapeutic methods that affect the reactivation of FMR1 gene expression: treatment with inhibitors of chromatin-modifying enzymes, the use of noncoding RNAs and the application of gene therapy. Inhibitors of chromatin-modifying enzymes are not clinically applicable because of their low reactivity and high cytotoxicity, and noncoding RNAs are currently only under study. Thus, we discuss gene therapy as the most promising approach for treating FXS in the near future.
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Affiliation(s)
- Ekaterina M Shitik
- State Research Center of Virology and Biotechnology "Vector", Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (FBRI SRC VB "Vector", Rospotrebnadzor), Koltsovo, Novosibirsk Region, Russia
| | - Anastasia A Velmiskina
- State Research Center of Virology and Biotechnology "Vector", Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (FBRI SRC VB "Vector", Rospotrebnadzor), Koltsovo, Novosibirsk Region, Russia
| | - Alexander A Dolskiy
- State Research Center of Virology and Biotechnology "Vector", Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (FBRI SRC VB "Vector", Rospotrebnadzor), Koltsovo, Novosibirsk Region, Russia
| | - Dmitry V Yudkin
- State Research Center of Virology and Biotechnology "Vector", Federal Service for Surveillance on Consumer Rights Protection and Human Well-being (FBRI SRC VB "Vector", Rospotrebnadzor), Koltsovo, Novosibirsk Region, Russia.
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14
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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: 40] [Impact Index Per Article: 8.0] [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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15
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Dulman RS, Auta J, Teppen T, Pandey SC. Acute Ethanol Produces Ataxia and Induces Fmr1 Expression via Histone Modifications in the Rat Cerebellum. Alcohol Clin Exp Res 2019; 43:1191-1198. [PMID: 30969437 DOI: 10.1111/acer.14044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/04/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND The cerebellum is fundamental for motor coordination and therefore crucial in ethanol (EtOH)-induced ataxia. EtOH contributes to cerebellar pathophysiology. Fragile-X mental retardation protein (FMRP) is a complex regulator of RNA and synaptic plasticity implicated in fragile-X tremor and ataxia syndrome, a phenotype featuring increased Fmr1 mRNA expression. Recent studies have implicated glutamatergic targets of FMRP in hereditary cerebellar ataxias including the main cerebellar excitatory amino acid (Eaa1) transporter and a subtype of metabotropic glutamate receptor (Grm5). However, EtOH-induced changes in cerebellar Fmr1 expression and its epigenetic regulation have not been investigated. Here, we examined the effects of acute EtOH exposure on ataxic behavior, gene expression, and epigenetic regulation of the Fmr1 gene and its glutamatergic targets in the rat cerebellum. METHODS Male adult Sprague Dawley rats received acute EtOH (2 g/kg) intraperitoneally 1 hour prior to ataxic behavioral testing on the accelerating rotarod and were sacrificed immediately thereafter. Cerebellar tissues were analyzed for gene expression and epigenetic regulation of the Fmr1 gene and its glutamatergic targets in the rat cerebellum using real-time quantitative polymerase chain reaction (PCR) and chromatin immunoprecipitation. RESULTS Acute EtOH exposure caused marked ataxia on the accelerating rotarod test compared with saline-treated controls. This ataxic response was associated with increases in mRNA levels of Fmr1, postsynaptic density 95 (Psd95), Eaa1, and Grm5 in the cerebellum. In addition, we found increased H3K27 acetylation both at the promoter region of Fmr1 and at a proposed cyclic adenosine monophosphate (cAMP) response-element binding (CREB) site downstream of the Fmr1 transcription start site. Furthermore, acute EtOH exposure significantly increased Creb1 and the histone acetyltransferases (HAT) CREB binding protein (Cbp), and p300 mRNA transcripts. CONCLUSIONS Overall, EtOH regulates cerebellar Fmr1 expression most likely via HAT-mediated increase in histone acetylation. We propose that FMRP regulation of glutamatergic transcripts plays an important role in disrupting the excitatory-inhibitory balance in the cerebellum underlying EtOH-induced ataxia.
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Affiliation(s)
- Russell S Dulman
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois
| | - James Auta
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois
| | - Tara Teppen
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Subhash C Pandey
- Department of Psychiatry, Center for Alcohol Research in Epigenetics, University of Illinois at Chicago, Chicago, Illinois.,Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
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16
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Wang Z, Khemani P, Schmitt LM, Lui S, Mosconi MW. Static and dynamic postural control deficits in aging fragile X mental retardation 1 (FMR1) gene premutation carriers. J Neurodev Disord 2019; 11:2. [PMID: 30665341 PMCID: PMC6341725 DOI: 10.1186/s11689-018-9261-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 12/26/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Individuals with premutation alleles of the fragile X mental retardation 1 (FMR1) gene are at risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS) during aging. Characterization of motor issues associated with aging in FMR1 premutation carriers is needed to determine neurodegenerative processes and establish new biobehavioral indicators to help identify individuals at greatest risk of developing FXTAS. METHODS We examined postural stability in 18 premutation carriers ages 46-77 years and 14 age-matched healthy controls. Participants completed a test of static stance and two tests of dynamic postural sway on a force platform to quantify postural variability and complexity. CGG repeat length was measured for each premutation carrier, and MRI and neurological evaluations were conducted to identify carriers who currently met criteria for FXTAS. Of the 18 premutation carriers, seven met criteria for definite/probable FXTAS (FXTAS+), seven showed no MRI or neurological signs of FXTAS (FXTAS-), and four were inconclusive due to insufficient data. RESULTS Compared to controls, premutation carriers showed increased center of pressure (COP) variability in the mediolateral (COPML) direction during static stance and reduced COP variability in the anterior-posterior (COPAP) direction during dynamic AP sway. They also showed reductions in COPML complexity during each postural condition. FXTAS+ individuals showed reduced COPAP variability compared to FXTAS- carriers and healthy controls during dynamic AP sway. Across all carriers, increased sway variability during static stance and decreased sway variability in target directions during dynamic sways were associated with greater CGG repeat length and more severe neurologically rated posture and gait abnormalities. CONCLUSION Our findings indicate that aging FMR1 premutation carriers show static and dynamic postural control deficits relative to healthy controls implicating degenerative processes of spinocerebellar and cerebellar-brainstem circuits that may be independent of or precede the onset of FXTAS. Our finding that FXTAS+ and FXTAS- premutation carriers differed on their level of intentional AP sway suggests that neural mechanisms of dynamic postural control may be differentially impacted in patients with FXTAS, and its measurement may be useful for rapidly and precisely identifying disease presence and onset.
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Affiliation(s)
- Zheng Wang
- Department of Occupational Therapy, University of Florida, Gainesville, FL, 32611, USA. .,University of Florida, 1225 Center Drive, PO Box 100164, Gainesville, FL, 326100164, USA.
| | - Pravin Khemani
- Department of Neurology, Swedish Neuroscience Institute, Seattle, WA, 98121, USA
| | - Lauren M Schmitt
- Division of Developmental and Behavioral Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Su Lui
- Huaxi Magnetic Resonance Research Center (HMRRC), Department of Radiology, West China Hospital of Sichuan University, Chengdu, 610041, Sichuan, China
| | - Matthew W Mosconi
- Schiefelbusch Institute for Life Span Studies, University of Kansas, Lawrence, KS, 66045, USA.,Clinical Child Psychology Program, University of Kansas, Lawrence, KS, 66045, USA.,Kansas Center for Autism Research and Training (K-CART), University of Kansas, Lawrence, KS, 66045, USA
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17
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Melancia F, Trezza V. Modelling fragile X syndrome in the laboratory setting: A behavioral perspective. Behav Brain Res 2018; 350:149-163. [DOI: 10.1016/j.bbr.2018.04.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/24/2018] [Accepted: 04/24/2018] [Indexed: 12/13/2022]
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18
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Haenfler JM, Skariah G, Rodriguez CM, Monteiro da Rocha A, Parent JM, Smith GD, Todd PK. Targeted Reactivation of FMR1 Transcription in Fragile X Syndrome Embryonic Stem Cells. Front Mol Neurosci 2018; 11:282. [PMID: 30158855 PMCID: PMC6104480 DOI: 10.3389/fnmol.2018.00282] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/25/2018] [Indexed: 12/15/2022] Open
Abstract
Fragile X Syndrome (FXS) is the most common inherited cause of intellectual disability and autism. It results from expansion of a CGG nucleotide repeat in the 5′ untranslated region (UTR) of FMR1. Large expansions elicit repeat and promoter hyper-methylation, heterochromatin formation, FMR1 transcriptional silencing and loss of the Fragile X protein, FMRP. Efforts aimed at correcting the sequelae resultant from FMRP loss have thus far proven insufficient, perhaps because of FMRP’s pleiotropic functions. As the repeats do not disrupt the FMRP coding sequence, reactivation of endogenous FMR1 gene expression could correct the proximal event in FXS pathogenesis. Here we utilize the Clustered Regularly Interspaced Palindromic Repeats/deficient CRISPR associated protein 9 (CRISPR/dCas9) system to selectively re-activate transcription from the silenced FMR1 locus. Fusion of the transcriptional activator VP192 to dCas9 robustly enhances FMR1 transcription and increases FMRP levels when targeted directly to the CGG repeat in human cells. Using a previously uncharacterized FXS human embryonic stem cell (hESC) line which acquires transcriptional silencing with serial passaging, we achieved locus-specific transcriptional re-activation of FMR1 messenger RNA (mRNA) expression despite promoter and repeat methylation. However, these changes at the transcript level were not coupled with a significant elevation in FMRP protein expression in FXS cells. These studies demonstrate that directing a transcriptional activator to CGG repeats is sufficient to selectively reactivate FMR1 mRNA expression in Fragile X patient stem cells.
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Affiliation(s)
- Jill M Haenfler
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States.,Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Geena Skariah
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Caitlin M Rodriguez
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| | - Andre Monteiro da Rocha
- Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, United States
| | - Jack M Parent
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States.,Veterans Administration Ann Arbor Healthcare System, Ann Arbor, MI, United States
| | - Gary D Smith
- Departments of Obstetrics/Gynecology, Physiology, and Urology, University of Michigan, Ann Arbor, MI, United States
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States.,Veterans Administration Ann Arbor Healthcare System, Ann Arbor, MI, United States
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19
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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: 77] [Impact Index Per Article: 12.8] [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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20
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Liu XS, Wu H, Krzisch M, Wu X, Graef J, Muffat J, Hnisz D, Li CH, Yuan B, Xu C, Li Y, Vershkov D, Cacace A, Young RA, Jaenisch R. Rescue of Fragile X Syndrome Neurons by DNA Methylation Editing of the FMR1 Gene. Cell 2018; 172:979-992.e6. [PMID: 29456084 PMCID: PMC6375087 DOI: 10.1016/j.cell.2018.01.012] [Citation(s) in RCA: 285] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/06/2017] [Accepted: 01/07/2018] [Indexed: 12/14/2022]
Abstract
Fragile X syndrome (FXS), the most common genetic form of intellectual disability in males, is caused by silencing of the FMR1 gene associated with hypermethylation of the CGG expansion mutation in the 5' UTR of FMR1 in FXS patients. Here, we applied recently developed DNA methylation editing tools to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/single guide RNA (sgRNA) switched the heterochromatin status of the upstream FMR1 promoter to an active chromatin state, restoring a persistent expression of FMR1 in FXS iPSCs. Neurons derived from methylation-edited FXS iPSCs rescued the electrophysiological abnormalities and restored a wild-type phenotype upon the mutant neurons. FMR1 expression in edited neurons was maintained in vivo after engrafting into the mouse brain. Finally, demethylation of the CGG repeats in post-mitotic FXS neurons also reactivated FMR1. Our data establish that demethylation of the CGG expansion is sufficient for FMR1 reactivation, suggesting potential therapeutic strategies for FXS.
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Affiliation(s)
- X Shawn Liu
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Hao Wu
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Fulcrum Therapeutics, One Kendall Square, Binney Street b7102, Cambridge, MA 02139, USA
| | - Marine Krzisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Xuebing Wu
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - John Graef
- Fulcrum Therapeutics, One Kendall Square, Binney Street b7102, Cambridge, MA 02139, USA
| | - Julien Muffat
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Denes Hnisz
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Charles H Li
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Bingbing Yuan
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Chuanyun Xu
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Yun Li
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Dan Vershkov
- The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Angela Cacace
- Fulcrum Therapeutics, One Kendall Square, Binney Street b7102, Cambridge, MA 02139, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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21
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Manor E, Jabareen A, Magal N, Kofman A, Hagerman RJ, Tassone F. Prenatal Diagnosis of Fragile X: Can a Full Mutation Allele in the FMR1 Gene Contract to a Normal Size? Front Genet 2017; 8:158. [PMID: 29163631 PMCID: PMC5675867 DOI: 10.3389/fgene.2017.00158] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 10/09/2017] [Indexed: 01/29/2023] Open
Abstract
Here we describe a case of a prenatal diagnosis of a male fetus that inherited the unstable allele from his full mutation mosaic mother (29, 160, >200 CGG repeats) reduced to a normal size range (19 CGG repeats). Haplotype analysis showed that the fetus 19 CGG repeats allele derived from the maternal unstable allele which was inherited from his maternal grandmother. No size mosaicism was detected by testing the DNA from in vitro cultured samples, including seventh passage culture as well as from two amniocentesis samples. Sequence analysis confirmed that the allele was 19 CGG repeats long. Methylation assay showed no methylation. Although none of the techniques used in this study can provide with absolute certainty the diagnosis, the results strongly indicate the presence in the fetus of an allele with a CGG repeat number in the normal range. Because this is a prenatal diagnosis case, the crucial question is whether the 19 CGG allele derived from the maternal unstable expanded allele, which contracted to the normal range, became a normal stable allele or a normal unstable allele which could expand in the next generation. It is also possible that allele size mosaicism of the FMR1 gene that went undetected exists. Because this is a prenatal diagnosis case, we cannot with certainty exclude the presence of an undetected expanded allele of the FMR1 gene, in addition to the 19 CGG allele derived from an unstable expanded allele, which contracted to the normal range.
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Affiliation(s)
- Esther Manor
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel.,Genetics Institute, Soroka Medical Center, Beersheba, Israel
| | - Azhar Jabareen
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel.,Genetics Institute, Soroka Medical Center, Beersheba, Israel
| | - Nurit Magal
- Department of Medical Genetics, Rabin Medical Center, Petah Tikva, Israel.,Felsenstein Medical Research Center, Rabin Medical Center, Petah Tikva, Israel
| | - Arei Kofman
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel.,Genetics Institute, Soroka Medical Center, Beersheba, Israel
| | - Randi J Hagerman
- Department of Pediatrics, MIND Institute, UC Davis Medical Center, Sacramento, CA, United States
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Davis, CA, United States.,MIND Institute, UC Davis Medical Center, Sacramento, CA, United States
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22
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Mila M, Alvarez-Mora M, Madrigal I, Rodriguez-Revenga L. Fragile X syndrome: An overview and update of the FMR1
gene. Clin Genet 2017; 93:197-205. [DOI: 10.1111/cge.13075] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/09/2017] [Accepted: 06/10/2017] [Indexed: 01/31/2023]
Affiliation(s)
- M. Mila
- Biochemistry and Molecular Genetics Department, Hospital Clinic; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Instituto de Salud Carlos III; Madrid Spain
| | - M.I. Alvarez-Mora
- Biochemistry and Molecular Genetics Department, Hospital Clinic; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Instituto de Salud Carlos III; Madrid Spain
| | - I. Madrigal
- Biochemistry and Molecular Genetics Department, Hospital Clinic; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Instituto de Salud Carlos III; Madrid Spain
| | - L. Rodriguez-Revenga
- Biochemistry and Molecular Genetics Department, Hospital Clinic; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Barcelona Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Instituto de Salud Carlos III; Madrid Spain
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23
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CpG and Non-CpG Methylation in Epigenetic Gene Regulation and Brain Function. Genes (Basel) 2017; 8:genes8060148. [PMID: 28545252 PMCID: PMC5485512 DOI: 10.3390/genes8060148] [Citation(s) in RCA: 208] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/18/2017] [Accepted: 05/19/2017] [Indexed: 12/13/2022] Open
Abstract
DNA methylation is a major epigenetic mark with important roles in genetic regulation. Methylated cytosines are found primarily at CpG dinucleotides, but are also found at non-CpG sites (CpA, CpT, and CpC). The general functions of CpG and non-CpG methylation include gene silencing or activation depending on the methylated regions. CpG and non-CpG methylation are found throughout the whole genome, including repetitive sequences, enhancers, promoters, and gene bodies. Interestingly, however, non-CpG methylation is restricted to specific cell types, such as pluripotent stem cells, oocytes, neurons, and glial cells. Thus, accumulation of methylation at non-CpG sites and CpG sites in neurons seems to be involved in development and disease etiology. Here, we provide an overview of CpG and non-CpG methylation and their roles in neurological diseases.
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