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Tassone F, Protic D, Allen EG, Archibald AD, Baud A, Brown TW, Budimirovic DB, Cohen J, Dufour B, Eiges R, Elvassore N, Gabis LV, Grudzien SJ, Hall DA, Hessl D, Hogan A, Hunter JE, Jin P, Jiraanont P, Klusek J, Kooy RF, Kraan CM, Laterza C, Lee A, Lipworth K, Losh M, Loesch D, Lozano R, Mailick MR, Manolopoulos A, Martinez-Cerdeno V, McLennan Y, Miller RM, Montanaro FAM, Mosconi MW, Potter SN, Raspa M, Rivera SM, Shelly K, Todd PK, Tutak K, Wang JY, Wheeler A, Winarni TI, Zafarullah M, Hagerman RJ. Insight and Recommendations for Fragile X-Premutation-Associated Conditions from the Fifth International Conference on FMR1 Premutation. Cells 2023; 12:2330. [PMID: 37759552 PMCID: PMC10529056 DOI: 10.3390/cells12182330] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/09/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
The premutation of the fragile X messenger ribonucleoprotein 1 (FMR1) gene is characterized by an expansion of the CGG trinucleotide repeats (55 to 200 CGGs) in the 5' untranslated region and increased levels of FMR1 mRNA. Molecular mechanisms leading to fragile X-premutation-associated conditions (FXPAC) include cotranscriptional R-loop formations, FMR1 mRNA toxicity through both RNA gelation into nuclear foci and sequestration of various CGG-repeat-binding proteins, and the repeat-associated non-AUG (RAN)-initiated translation of potentially toxic proteins. Such molecular mechanisms contribute to subsequent consequences, including mitochondrial dysfunction and neuronal death. Clinically, premutation carriers may exhibit a wide range of symptoms and phenotypes. Any of the problems associated with the premutation can appropriately be called FXPAC. Fragile X-associated tremor/ataxia syndrome (FXTAS), fragile X-associated primary ovarian insufficiency (FXPOI), and fragile X-associated neuropsychiatric disorders (FXAND) can fall under FXPAC. Understanding the molecular and clinical aspects of the premutation of the FMR1 gene is crucial for the accurate diagnosis, genetic counseling, and appropriate management of affected individuals and families. This paper summarizes all the known problems associated with the premutation and documents the presentations and discussions that occurred at the International Premutation Conference, which took place in New Zealand in 2023.
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Affiliation(s)
- Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, CA 95817, USA;
- MIND Institute, University of California Davis, Davis, CA 95817, USA; (B.D.); (D.H.); (V.M.-C.)
| | - Dragana Protic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11129 Belgrade, Serbia;
- Fragile X Clinic, Special Hospital for Cerebral Palsy and Developmental Neurology, 11040 Belgrade, Serbia
| | - Emily Graves Allen
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA; (E.G.A.); (P.J.); (K.S.)
| | - Alison D. Archibald
- Victorian Clinical Genetics Services, Royal Children’s Hospital, Melbourne, VIC 3052, Australia;
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC 3052, Australia;
- Genomics in Society Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, VIC 3052, Australia
| | - Anna Baud
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614 Poznan, Poland; (A.B.); (K.T.)
| | - Ted W. Brown
- Central Clinical School, University of Sydney, Sydney, NSW 2006, Australia;
- Fragile X Association of Australia, Brookvale, NSW 2100, Australia;
- NYS Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA
| | - Dejan B. Budimirovic
- Department of Psychiatry, Fragile X Clinic, Kennedy Krieger Institute, Baltimore, MD 21205, USA;
- Department of Psychiatry & Behavioral Sciences-Child Psychiatry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Jonathan Cohen
- Fragile X Alliance Clinic, Melbourne, VIC 3161, Australia;
| | - Brett Dufour
- MIND Institute, University of California Davis, Davis, CA 95817, USA; (B.D.); (D.H.); (V.M.-C.)
- Department of Pathology and Laboratory Medicine, Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children of Northern California, School of Medicine, University of California Davis, Sacramento, CA 95817, USA;
| | - Rachel Eiges
- Stem Cell Research Laboratory, Medical Genetics Institute, Shaare Zedek Medical Center Affiliated with the Hebrew University School of Medicine, Jerusalem 91031, Israel;
| | - Nicola Elvassore
- Veneto Institute of Molecular Medicine (VIMM), 35129 Padova, Italy; (N.E.); (C.L.)
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | - Lidia V. Gabis
- Keshet Autism Center Maccabi Wolfson, Holon 5822012, Israel;
- Faculty of Medicine, Tel-Aviv University, Tel Aviv 6997801, Israel
| | - Samantha J. Grudzien
- Department of Neurology, University of Michigan, 4148 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA; (S.J.G.); (P.K.T.)
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Deborah A. Hall
- Department of Neurological Sciences, Rush University, Chicago, IL 60612, USA;
| | - David Hessl
- MIND Institute, University of California Davis, Davis, CA 95817, USA; (B.D.); (D.H.); (V.M.-C.)
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California Davis, Sacramento, CA 95817, USA
| | - Abigail Hogan
- Department of Communication Sciences and Disorders, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA; (A.H.); (J.K.)
| | - Jessica Ezzell Hunter
- RTI International, Research Triangle Park, NC 27709, USA; (J.E.H.); (S.N.P.); (M.R.); (A.W.)
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA; (E.G.A.); (P.J.); (K.S.)
| | - Poonnada Jiraanont
- Faculty of Medicine, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand;
| | - Jessica Klusek
- Department of Communication Sciences and Disorders, Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA; (A.H.); (J.K.)
| | - R. Frank Kooy
- Department of Medical Genetics, University of Antwerp, 2000 Antwerp, Belgium;
| | - Claudine M. Kraan
- Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC 3052, Australia;
- Diagnosis and Development, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
| | - Cecilia Laterza
- Veneto Institute of Molecular Medicine (VIMM), 35129 Padova, Italy; (N.E.); (C.L.)
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | - Andrea Lee
- Fragile X New Zealand, Nelson 7040, New Zealand;
| | - Karen Lipworth
- Fragile X Association of Australia, Brookvale, NSW 2100, Australia;
| | - Molly Losh
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60201, USA;
| | - Danuta Loesch
- School of Psychology and Public Health, La Trobe University, Melbourne, VIC 3086, Australia;
| | - Reymundo Lozano
- Departments of Genetics and Genomic Sciences and Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA;
| | - Marsha R. Mailick
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Apostolos Manolopoulos
- Intramural Research Program, Laboratory of Clinical Investigation, National Institute on Aging, Baltimore, MD 21224, USA;
| | - Veronica Martinez-Cerdeno
- MIND Institute, University of California Davis, Davis, CA 95817, USA; (B.D.); (D.H.); (V.M.-C.)
- Department of Pathology and Laboratory Medicine, Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children of Northern California, School of Medicine, University of California Davis, Sacramento, CA 95817, USA;
| | - Yingratana McLennan
- Department of Pathology and Laboratory Medicine, Institute for Pediatric Regenerative Medicine, Shriners Hospitals for Children of Northern California, School of Medicine, University of California Davis, Sacramento, CA 95817, USA;
| | | | - Federica Alice Maria Montanaro
- Child and Adolescent Neuropsychiatry Unit, Department of Neuroscience, Bambino Gesù Children’s Hospital, IRCCS, 00165 Rome, Italy;
- Department of Education, Psychology, Communication, University of Bari Aldo Moro, 70121 Bari, Italy
| | - 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
| | - Sarah Nelson Potter
- RTI International, Research Triangle Park, NC 27709, USA; (J.E.H.); (S.N.P.); (M.R.); (A.W.)
| | - Melissa Raspa
- RTI International, Research Triangle Park, NC 27709, USA; (J.E.H.); (S.N.P.); (M.R.); (A.W.)
| | - Susan M. Rivera
- Department of Psychology, University of Maryland, College Park, MD 20742, USA;
| | - Katharine Shelly
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA; (E.G.A.); (P.J.); (K.S.)
| | - Peter K. Todd
- Department of Neurology, University of Michigan, 4148 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA; (S.J.G.); (P.K.T.)
- Ann Arbor Veterans Administration Healthcare, Ann Arbor, MI 48105, USA
| | - Katarzyna Tutak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Uniwersytetu Poznańskiego 6, 61-614 Poznan, Poland; (A.B.); (K.T.)
| | - Jun Yi Wang
- Center for Mind and Brain, University of California Davis, Davis, CA 95618, USA;
| | - Anne Wheeler
- RTI International, Research Triangle Park, NC 27709, USA; (J.E.H.); (S.N.P.); (M.R.); (A.W.)
| | - Tri Indah Winarni
- Center for Biomedical Research (CEBIOR), Faculty of Medicine, Universitas Diponegoro, Semarang 502754, Central Java, Indonesia;
| | - Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California Davis, Sacramento, CA 95817, USA;
| | - Randi J. Hagerman
- MIND Institute, University of California Davis, Davis, CA 95817, USA; (B.D.); (D.H.); (V.M.-C.)
- Department of Pediatrics, School of Medicine, University of California Davis, Sacramento, CA 95817, USA
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Trajković J, Makevic V, Pesic M, Pavković-Lučić S, Milojevic S, Cvjetkovic S, Hagerman R, Budimirovic DB, Protic D. Drosophila melanogaster as a Model to Study Fragile X-Associated Disorders. Genes (Basel) 2022; 14:genes14010087. [PMID: 36672829 PMCID: PMC9859539 DOI: 10.3390/genes14010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 12/30/2022] Open
Abstract
Fragile X syndrome (FXS) is a global neurodevelopmental disorder caused by the expansion of CGG trinucleotide repeats (≥200) in the Fragile X Messenger Ribonucleoprotein 1 (FMR1) gene. FXS is the hallmark of Fragile X-associated disorders (FXD) and the most common monogenic cause of inherited intellectual disability and autism spectrum disorder. There are several animal models used to study FXS. In the FXS model of Drosophila, the only ortholog of FMR1, dfmr1, is mutated so that its protein is missing. This model has several relevant phenotypes, including defects in the circadian output pathway, sleep problems, memory deficits in the conditioned courtship and olfactory conditioning paradigms, deficits in social interaction, and deficits in neuronal development. In addition to FXS, a model of another FXD, Fragile X-associated tremor/ataxia syndrome (FXTAS), has also been established in Drosophila. This review summarizes many years of research on FXD in Drosophila models.
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Affiliation(s)
- Jelena Trajković
- Faculty of Biology, University of Belgrade, 11000 Belgrade, Serbia
| | - Vedrana Makevic
- Department of Pathophysiology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Milica Pesic
- Institute of Human Genetics, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | | | - Sara Milojevic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Smiljana Cvjetkovic
- Department of Humanities, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
| | - Randi Hagerman
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817, USA
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA 95817, USA
| | - Dejan B. Budimirovic
- Department of Psychiatry, Fragile X Clinic, Kennedy Krieger Institute, Baltimore, MD 21205, USA
- Department of Psychiatry & Behavioral Sciences-Child Psychiatry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Dragana Protic
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- Correspondence:
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Yousuf A, Ahmed N, Qurashi A. Non-canonical DNA/RNA structures associated with the pathogenesis of Fragile X-associated tremor/ataxia syndrome and Fragile X syndrome. Front Genet 2022; 13:866021. [PMID: 36110216 PMCID: PMC9468596 DOI: 10.3389/fgene.2022.866021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X syndrome (FXS) are primary examples of fragile X-related disorders (FXDs) caused by abnormal expansion of CGG repeats above a certain threshold in the 5′-untranslated region of the fragile X mental retardation (FMR1) gene. Both diseases have distinct clinical manifestations and molecular pathogenesis. FXTAS is a late-adult-onset neurodegenerative disorder caused by a premutation (PM) allele (CGG expansion of 55–200 repeats), resulting in FMR1 gene hyperexpression. On the other hand, FXS is a neurodevelopmental disorder that results from a full mutation (FM) allele (CGG expansions of ≥200 repeats) leading to heterochromatization and transcriptional silencing of the FMR1 gene. The main challenge is to determine how CGG repeat expansion affects the fundamentally distinct nature of FMR1 expression in FM and PM ranges. Abnormal CGG repeat expansions form a variety of non-canonical DNA and RNA structures that can disrupt various cellular processes and cause distinct effects in PM and FM alleles. Here, we review these structures and how they are related to underlying mutations and disease pathology in FXS and FXTAS. Finally, as new CGG expansions within the genome have been identified, it will be interesting to determine their implications in disease pathology and treatment.
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Liufu T, Zheng Y, Yu J, Yuan Y, Wang Z, Deng J, Hong D. The polyG diseases: a new disease entity. Acta Neuropathol Commun 2022; 10:79. [PMID: 35642014 PMCID: PMC9153130 DOI: 10.1186/s40478-022-01383-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/16/2022] [Indexed: 12/20/2022] Open
Abstract
Recently, inspired by the similar clinical and pathological features shared with fragile X-associated tremor/ataxia syndrome (FXTAS), abnormal expansion of CGG repeats in the 5' untranslated region has been found in neuronal intranuclear inclusion disease (NIID), oculopharyngeal myopathy with leukoencephalopathy (OPML), and oculopharyngodistal myopathy (OPDMs). Although the upstream open reading frame has not been elucidated in OPML and OPDMs, polyglycine (polyG) translated by expanded CGG repeats is reported to be as a primary pathogenesis in FXTAS and NIID. Collectively, these findings indicate a new disease entity, the polyG diseases. In this review, we state the common clinical manifestations, pathological features, mechanisms, and potential therapies in these diseases, and provide preliminary opinions about future research in polyG diseases.
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Affiliation(s)
- Tongling Liufu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yilei Zheng
- Department of Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jiaxi Yu
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, Beijing, China
| | - Zhaoxia Wang
- Department of Neurology, Peking University First Hospital, Beijing, China.,Beijing Key Laboratory of Neurovascular Disease Discovery, Beijing, China
| | - Jianwen Deng
- Department of Neurology, Peking University First Hospital, Beijing, China. .,Beijing Key Laboratory of Neurovascular Disease Discovery, Beijing, China.
| | - Daojun Hong
- Department of Neurology, The First Affiliated Hospital of Nanchang University, Nanchang, China. .,Department of Medical Genetics, The First Affiliated Hospital of Nanchang University, Nanchang, China.
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Tello JA, Williams HE, Eppler RM, Steinhilb ML, Khanna M. Animal Models of Neurodegenerative Disease: Recent Advances in Fly Highlight Innovative Approaches to Drug Discovery. Front Mol Neurosci 2022; 15:883358. [PMID: 35514431 PMCID: PMC9063566 DOI: 10.3389/fnmol.2022.883358] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/21/2022] [Indexed: 12/22/2022] Open
Abstract
Neurodegenerative diseases represent a formidable challenge to global health. As advances in other areas of medicine grant healthy living into later decades of life, aging diseases such as Alzheimer's disease (AD) and other neurodegenerative disorders can diminish the quality of these additional years, owed largely to the lack of efficacious treatments and the absence of durable cures. Alzheimer's disease prevalence is predicted to more than double in the next 30 years, affecting nearly 15 million Americans, with AD-associated costs exceeding $1 billion by 2050. Delaying onset of AD and other neurodegenerative diseases is critical to improving the quality of life for patients and reducing the burden of disease on caregivers and healthcare systems. Significant progress has been made to model disease pathogenesis and identify points of therapeutic intervention. While some researchers have contributed to our understanding of the proteins and pathways that drive biological dysfunction in disease using in vitro and in vivo models, others have provided mathematical, biophysical, and computational technologies to identify potential therapeutic compounds using in silico modeling. The most exciting phase of the drug discovery process is now: by applying a target-directed approach that leverages the strengths of multiple techniques and validates lead hits using Drosophila as an animal model of disease, we are on the fast-track to identifying novel therapeutics to restore health to those impacted by neurodegenerative disease.
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Affiliation(s)
- Judith A. Tello
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States
- Center of Innovation in Brain Science, Tucson, AZ, United States
| | - Haley E. Williams
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States
- Center of Innovation in Brain Science, Tucson, AZ, United States
| | - Robert M. Eppler
- Department of Biology, Central Michigan University, Mount Pleasant, MI, United States
| | - Michelle L. Steinhilb
- Department of Biology, Central Michigan University, Mount Pleasant, MI, United States
| | - May Khanna
- Department of Pharmacology, College of Medicine, University of Arizona, Tucson, AZ, United States
- Center of Innovation in Brain Science, Tucson, AZ, United States
- Department of Molecular Pathobiology, New York University, New York, NY, United States
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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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Costa-Rodrigues C, Couceiro J, Moreno E. Cell competition from development to neurodegeneration. Dis Model Mech 2021; 14:269331. [PMID: 34190316 PMCID: PMC8277968 DOI: 10.1242/dmm.048926] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cell competition is a process by which suboptimal cells are eliminated to the benefit of cells with higher fitness. It is a surveillance mechanism that senses differences in the fitness status by several modes, such as expression of fitness fingerprints, survival factor uptake rate and resistance to mechanical stress. Fitness fingerprints-mediated cell competition recognizes isoforms of the transmembrane protein Flower, and translates the relative fitness of cells into distinct fates through the Flower code. Impairments in cell competition potentiate the development of diseases like cancer and ageing-related pathologies. In cancer, malignant cells acquire a supercompetitor behaviour, killing the neighbouring cells and overtaking the tissue, thus avoiding elimination. Neurodegenerative disorders affect millions of people and are characterized by cognitive decline and locomotor deficits. Alzheimer's disease is the most common form of dementia, and one of the largely studied diseases. However, the cellular processes taking place remain unclear. Drosophila melanogaster is an emerging neurodegeneration model due to its versatility as a tool for genetic studies. Research in a Drosophila Alzheimer's disease model detected fitness markers in the suboptimal and hyperactive neurons, thus establishing a link between cell competition and Alzheimer's disease. In this Review, we overview cell competition and the new insights related to neurodegenerative disorders, and discuss how research in the field might contribute to the development of new therapeutic targets for these diseases.
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Affiliation(s)
| | - Joana Couceiro
- Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Eduardo Moreno
- Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
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Abstract
PURPOSE OF REVIEW The purpose of this paper is to review the prevalence, pathophysiology, and management of fragile X-associated tremor/ataxia syndrome (FXTAS). RECENT FINDINGS The pathophysiology of FXTAS involves ribonucleic acid (RNA) toxicity due to elevated levels of the premutation-expanded CGG (eoxycytidylate-deoxyguanylate-deoxyguanylate)-repeat FMR1 mRNA, which can sequester a variety of proteins important for neuronal function. A recent analysis of the inclusions in FXTAS demonstrates elevated levels of several proteins, including small ubiquitin-related modifiers 1/2 (SUMO1/2), that target molecules for the proteasome, suggesting that some aspect(s) of proteasomal function may be altered in FXTAS. Recent neuropathological studies show that Parkinson disease and Alzheimer disease can sometimes co-occur with FXTAS. Lewy bodies can be found in 10% of the brains of patients with FXTAS. Microbleeds and iron deposition are also common in the neuropathology, in addition to white matter disease (WMD) and atrophy. SUMMARY The premutation occurs in 1:200 females and 1:400 males. Penetrance for FXTAS increases with age, though lower in females (16%) compared to over 60% of males by age 70. To diagnose FXTAS, an MRI is essential to document the presence of WMD, a primary component of the diagnostic criteria. Pain can be a significant feature of FXTAS and is seen in approximately 50% of patients.
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Xu K, Li Y, Allen EG, Jin P. Therapeutic Development for CGG Repeat Expansion-Associated Neurodegeneration. Front Cell Neurosci 2021; 15:655568. [PMID: 34054431 PMCID: PMC8149615 DOI: 10.3389/fncel.2021.655568] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/12/2021] [Indexed: 12/16/2022] Open
Abstract
Non-coding repeat expansions, such as CGG, GGC, CUG, CCUG, and GGGGCC, have been shown to be involved in many human diseases, particularly neurological disorders. Of the diverse pathogenic mechanisms proposed in these neurodegenerative diseases, dysregulated RNA metabolism has emerged as an important contributor. Expanded repeat RNAs that form particular structures aggregate to form RNA foci, sequestering various RNA binding proteins and consequently altering RNA splicing, transport, and other downstream biological processes. One of these repeat expansion-associated diseases, fragile X-associated tremor/ataxia syndrome (FXTAS), is caused by a CGG repeat expansion in the 5'UTR region of the fragile X mental retardation 1 (FMR1) gene. Moreover, recent studies have revealed abnormal GGC repeat expansion within the 5'UTR region of the NOTCH2NLC gene in both essential tremor (ET) and neuronal intranuclear inclusion disease (NIID). These CGG repeat expansion-associated diseases share genetic, pathological, and clinical features. Identification of the similarities at the molecular level could lead to a better understanding of the disease mechanisms as well as developing novel therapeutic strategies. Here, we highlight our current understanding of the molecular pathogenesis of CGG repeat expansion-associated diseases and discuss potential therapeutic interventions for these neurological disorders.
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Affiliation(s)
- Keqin Xu
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States.,Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Yujing Li
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
| | - Emily G Allen
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States
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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: 1] [Impact Index Per Article: 0.3] [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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Yu AM, Choi YH, Tu MJ. RNA Drugs and RNA Targets for Small Molecules: Principles, Progress, and Challenges. Pharmacol Rev 2020; 72:862-898. [PMID: 32929000 PMCID: PMC7495341 DOI: 10.1124/pr.120.019554] [Citation(s) in RCA: 173] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
RNA-based therapies, including RNA molecules as drugs and RNA-targeted small molecules, offer unique opportunities to expand the range of therapeutic targets. Various forms of RNAs may be used to selectively act on proteins, transcripts, and genes that cannot be targeted by conventional small molecules or proteins. Although development of RNA drugs faces unparalleled challenges, many strategies have been developed to improve RNA metabolic stability and intracellular delivery. A number of RNA drugs have been approved for medical use, including aptamers (e.g., pegaptanib) that mechanistically act on protein target and small interfering RNAs (e.g., patisiran and givosiran) and antisense oligonucleotides (e.g., inotersen and golodirsen) that directly interfere with RNA targets. Furthermore, guide RNAs are essential components of novel gene editing modalities, and mRNA therapeutics are under development for protein replacement therapy or vaccination, including those against unprecedented severe acute respiratory syndrome coronavirus pandemic. Moreover, functional RNAs or RNA motifs are highly structured to form binding pockets or clefts that are accessible by small molecules. Many natural, semisynthetic, or synthetic antibiotics (e.g., aminoglycosides, tetracyclines, macrolides, oxazolidinones, and phenicols) can directly bind to ribosomal RNAs to achieve the inhibition of bacterial infections. Therefore, there is growing interest in developing RNA-targeted small-molecule drugs amenable to oral administration, and some (e.g., risdiplam and branaplam) have entered clinical trials. Here, we review the pharmacology of novel RNA drugs and RNA-targeted small-molecule medications, with a focus on recent progresses and strategies. Challenges in the development of novel druggable RNA entities and identification of viable RNA targets and selective small-molecule binders are discussed. SIGNIFICANCE STATEMENT: With the understanding of RNA functions and critical roles in diseases, as well as the development of RNA-related technologies, there is growing interest in developing novel RNA-based therapeutics. This comprehensive review presents pharmacology of both RNA drugs and RNA-targeted small-molecule medications, focusing on novel mechanisms of action, the most recent progress, and existing challenges.
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MESH Headings
- Aptamers, Nucleotide/pharmacology
- Aptamers, Nucleotide/therapeutic use
- Betacoronavirus
- COVID-19
- Chemistry Techniques, Analytical/methods
- Chemistry Techniques, Analytical/standards
- Clustered Regularly Interspaced Short Palindromic Repeats
- Coronavirus Infections/drug therapy
- Drug Delivery Systems/methods
- Drug Development/organization & administration
- Drug Discovery
- Humans
- MicroRNAs/pharmacology
- MicroRNAs/therapeutic use
- Oligonucleotides, Antisense/pharmacology
- Oligonucleotides, Antisense/therapeutic use
- Pandemics
- Pneumonia, Viral/drug therapy
- RNA/adverse effects
- RNA/drug effects
- RNA/pharmacology
- RNA, Antisense/pharmacology
- RNA, Antisense/therapeutic use
- RNA, Messenger/drug effects
- RNA, Messenger/pharmacology
- RNA, Ribosomal/drug effects
- RNA, Ribosomal/pharmacology
- RNA, Small Interfering/pharmacology
- RNA, Small Interfering/therapeutic use
- RNA, Viral/drug effects
- Ribonucleases/metabolism
- Riboswitch/drug effects
- SARS-CoV-2
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Affiliation(s)
- Ai-Ming Yu
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
| | - Young Hee Choi
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
| | - Mei-Juan Tu
- Department of Biochemistry and Molecular Medicine, UC Davis School of Medicine, Sacramento, California (A.-M.Y., Y.H.C., M.-J.T.) and College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Gyonggi-do, Republic of Korea (Y.H.C.)
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12
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Neddylation activity modulates the neurodegeneration associated with fragile X associated tremor/ataxia syndrome (FXTAS) through regulating Sima. Neurobiol Dis 2020; 143:105013. [PMID: 32653676 DOI: 10.1016/j.nbd.2020.105013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 04/25/2020] [Accepted: 07/07/2020] [Indexed: 11/20/2022] Open
Abstract
Fragile X associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder caused by expansion of CGG repeats in the 5' UTR of the fragile X mental retardation 1 (FMR1) gene. Using the well-established FXTAS Drosophila model, we performed a high-throughput chemical screen using 3200 small molecules. NSC363998 was identified to suppress the neurodegeneration caused by riboCGG (rCGG) repeats. Three predicted targets of a NSC363998 derivative are isopeptidases in the neddylation pathway and could modulate the neurotoxicity caused by the rCGG repeats. Decreasing levels of neddylation resulted in enhancing neurodegeneration phenotypes, while up-regulation could rescue the phenotypes. Furthermore, known neddylation substrates, Cul3 and Vhl, and their downstream target, Sima, were found to modulate rCGG90-dependent neurotoxicity. Our results suggest that altered neddylation activity can modulate the rCGG repeat-mediated toxicity by regulating Sima protein levels, which could serve as a potential therapeutic target for FXTAS.
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13
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Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): Pathophysiology and Clinical Implications. Int J Mol Sci 2020; 21:ijms21124391. [PMID: 32575683 PMCID: PMC7352421 DOI: 10.3390/ijms21124391] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
The fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder seen in older premutation (55-200 CGG repeats) carriers of FMR1. The premutation has excessive levels of FMR1 mRNA that lead to toxicity and mitochondrial dysfunction. The clinical features usually begin in the 60 s with an action or intention tremor followed by cerebellar ataxia, although 20% have only ataxia. MRI features include brain atrophy and white matter disease, especially in the middle cerebellar peduncles, periventricular areas, and splenium of the corpus callosum. Neurocognitive problems include memory and executive function deficits, although 50% of males can develop dementia. Females can be less affected by FXTAS because of a second X chromosome that does not carry the premutation. Approximately 40% of males and 16% of female carriers develop FXTAS. Since the premutation can occur in less than 1 in 200 women and 1 in 400 men, the FXTAS diagnosis should be considered in patients that present with tremor, ataxia, parkinsonian symptoms, neuropathy, and psychiatric problems. If a family history of a fragile X mutation is known, then FMR1 DNA testing is essential in patients with these symptoms.
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14
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Hall DA, Robertson EE, Leehey M, McAsey A, Ouyang B, Berry-Kravis E, O’Keefe JA. Open-label pilot clinical trial of citicoline for fragile X-associated tremor/ataxia syndrome (FXTAS). PLoS One 2020; 15:e0225191. [PMID: 32053612 PMCID: PMC7018079 DOI: 10.1371/journal.pone.0225191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 10/29/2019] [Indexed: 12/14/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late onset neurodegenerative disorder that is characterized by tremor, cerebellar ataxia, frequent falls, cognitive decline, and progressive loss of motor function. There are currently no approved treatments for this disorder. The purpose of this study was to determine if citicoline was safe for the treatment of tremor and balance abnormalities and to stabilize cognitive decline in patients with FXTAS. Ten participants with diagnosed FXTAS were administered 1000 mg of citicoline once daily for 12 months. Outcome measures and neurological examination were performed at baseline, 3 months, 6 months, and 12 months. The primary outcome was the FXTAS Rating Scale score. Secondary outcomes included change in a battery of neuropsychological tests, an instrumented Timed up and go test, computerized dynamic posturography, 9-hole pegboard test, and balance confidence and psychiatric symptom questionnaires. Safety was also evaluated. Citicoline treatment resulted in minimal adverse events in all but one subject over the course of the study. There was a significant improvement in the Beck Anxiety Inventory (p = 0.03) and the Stroop Color-Word test (p = 0.03), with all other measures remaining stable over the course of 12 months. This open-label pilot trial of citicoline for individuals with FXTAS showed that it is safe and well tolerated in this population. Registration: This trial was registered at ClinicalTrials.gov. Identifier: NCT0219710.
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Affiliation(s)
- Deborah A. Hall
- Department of Neurological Sciences, Rush University, Chicago, IL, United States of America
- * E-mail:
| | - Erin E. Robertson
- Department of Communication Sciences and Disorders, Northwestern, Chicago, IL, United States of America
| | - Maureen Leehey
- University of Colorado Denver, Aurora, CO, United States of America
| | - Andrew McAsey
- Department of Cell and Molecular Medicine, Rush University, Chicago, IL United States of America
| | - Bichun Ouyang
- Department of Neurological Sciences, Rush University, Chicago, IL, United States of America
| | - Elizabeth Berry-Kravis
- Department of Neurological Sciences, Rush University, Chicago, IL, United States of America
- Department of Biochemistry, Rush University, Chicago, IL, United States of America
- Department of Pediatrics, Rush University, Chicago, IL, United States of America
| | - Joan A. O’Keefe
- Department of Neurological Sciences, Rush University, Chicago, IL, United States of America
- Department of Cell and Molecular Medicine, Rush University, Chicago, IL United States of America
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15
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Verma AK, Khan E, Bhagwat SR, Kumar A. Exploring the Potential of Small Molecule-Based Therapeutic Approaches for Targeting Trinucleotide Repeat Disorders. Mol Neurobiol 2019; 57:566-584. [DOI: 10.1007/s12035-019-01724-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/29/2019] [Indexed: 12/18/2022]
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16
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Brown DG, Wobst HJ. Opportunities and Challenges in Phenotypic Screening for Neurodegenerative Disease Research. J Med Chem 2019; 63:1823-1840. [PMID: 31268707 DOI: 10.1021/acs.jmedchem.9b00797] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Toxic misfolded proteins potentially underly many neurodegenerative diseases, but individual targets which regulate these proteins and their downstream detrimental effects are often unknown. Phenotypic screening is an unbiased method to screen for novel targets and therapeutic molecules and span the range from primitive model organisms such as Sacchaomyces cerevisiae, which allow for high-throughput screening to patient-derived cell-lines that have a close connection to the disease biology but are limited in screening capacity. This perspective will review current phenotypic models, as well as the chemical screening strategies most often employed. Advances in in 3D cell cultures, high-content screens, robotic microscopy, CRISPR screening, and use of machine learning methods to process the enormous amount of data generated by these screens are certain to change the paradigm for phenotypic screening and will be discussed.
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Affiliation(s)
- Dean G Brown
- Hit Discovery, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
| | - Heike J Wobst
- Neuroscience, BioPharmaceuticals R&D, AstraZeneca, 35 Gatehouse Drive, Waltham, Massachusetts 02451, United States
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17
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Fragile X syndrome and fragile X-associated tremor ataxia syndrome. HANDBOOK OF CLINICAL NEUROLOGY 2018; 147:377-391. [PMID: 29325626 DOI: 10.1016/b978-0-444-63233-3.00025-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Fragile X-associated disorders encompass several conditions, which are caused by expansion mutations in the fragile X mental retardation 1 (FMR1) gene. Fragile X syndrome is the most common inherited etiology of intellectual disability and results from a full mutation or >200 CGG repeats in FMR1. It is associated with developmental delay, autism spectrum disorder, and seizures. Fragile X-associated tremor/ataxia syndrome is a progressive neurodegenerative disease that occurs in premutation carriers of 55-200 CGG repeats in FMR1 and is characterized by kinetic tremor, gait ataxia, parkinsonism, executive dysfunction, and neuropathy. Fragile X-associated primary ovarian insufficiency also occurs in premutation carrier women and manifests with infertility and early menopause. The diseases constituting fragile X-associated disorders differ mechanistically, due to the distinct molecular properties of premutation versus full mutations. Fragile X syndrome occurs when there is a lack of fragile X mental retardation protein (FMRP) due to FMR1 methylation and silencing. In fragile X-associated tremor ataxia syndrome, a toxic gain of function is postulated with the production of excess CGG repeat-containing FMR1 mRNA, abnormal translation of the repeat sequence leading to production of polyglycine, polyalanine, and other polypeptides and to outright deficits in translation leading to reduced FMRP at larger premutation sizes. The changes in underlying brain chemistry due to FMR1 mutations have led to therapeutic studies in these disorders, with some progress being made in fragile X syndrome. This paper also summarizes indications for testing, genetic counseling issues, and what the future holds for these disorders.
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18
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Monnier V, Llorens JV, Navarro JA. Impact of Drosophila Models in the Study and Treatment of Friedreich's Ataxia. Int J Mol Sci 2018; 19:E1989. [PMID: 29986523 PMCID: PMC6073496 DOI: 10.3390/ijms19071989] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 06/26/2018] [Accepted: 07/03/2018] [Indexed: 02/07/2023] Open
Abstract
Drosophila melanogaster has been for over a century the model of choice of several neurobiologists to decipher the formation and development of the nervous system as well as to mirror the pathophysiological conditions of many human neurodegenerative diseases. The rare disease Friedreich’s ataxia (FRDA) is not an exception. Since the isolation of the responsible gene more than two decades ago, the analysis of the fly orthologue has proven to be an excellent avenue to understand the development and progression of the disease, to unravel pivotal mechanisms underpinning the pathology and to identify genes and molecules that might well be either disease biomarkers or promising targets for therapeutic interventions. In this review, we aim to summarize the collection of findings provided by the Drosophila models but also to go one step beyond and propose the implications of these discoveries for the study and cure of this disorder. We will present the physiological, cellular and molecular phenotypes described in the fly, highlighting those that have given insight into the pathology and we will show how the ability of Drosophila to perform genetic and pharmacological screens has provided valuable information that is not easily within reach of other cellular or mammalian models.
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Affiliation(s)
- Véronique Monnier
- Unité de Biologie Fonctionnelle et Adaptative (BFA), Sorbonne Paris Cité, Université Paris Diderot, UMR8251 CNRS, 75013 Paris, France.
| | - Jose Vicente Llorens
- Department of Genetics, University of Valencia, Campus of Burjassot, 96100 Valencia, Spain.
| | - Juan Antonio Navarro
- Lehrstuhl für Entwicklungsbiologie, Universität Regensburg, 93040 Regensburg, Germany.
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19
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Drozd M, Bardoni B, Capovilla M. Modeling Fragile X Syndrome in Drosophila. Front Mol Neurosci 2018; 11:124. [PMID: 29713264 PMCID: PMC5911982 DOI: 10.3389/fnmol.2018.00124] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/29/2018] [Indexed: 01/18/2023] Open
Abstract
Intellectual disability (ID) and autism are hallmarks of Fragile X Syndrome (FXS), a hereditary neurodevelopmental disorder. The gene responsible for FXS is Fragile X Mental Retardation gene 1 (FMR1) encoding the Fragile X Mental Retardation Protein (FMRP), an RNA-binding protein involved in RNA metabolism and modulating the expression level of many targets. Most cases of FXS are caused by silencing of FMR1 due to CGG expansions in the 5'-UTR of the gene. Humans also carry the FXR1 and FXR2 paralogs of FMR1 while flies have only one FMR1 gene, here called dFMR1, sharing the same level of sequence homology with all three human genes, but functionally most similar to FMR1. This enables a much easier approach for FMR1 genetic studies. Drosophila has been widely used to investigate FMR1 functions at genetic, cellular, and molecular levels since dFMR1 mutants have many phenotypes in common with the wide spectrum of FMR1 functions that underlay the disease. In this review, we present very recent Drosophila studies investigating FMRP functions at genetic, cellular, molecular, and electrophysiological levels in addition to research on pharmacological treatments in the fly model. These studies have the potential to aid the discovery of pharmacological therapies for FXS.
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Affiliation(s)
- Małgorzata Drozd
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA (Neogenex), Valbonne, France
| | - Barbara Bardoni
- CNRS LIA (Neogenex), Valbonne, France.,Université Côte d'Azur, INSERM, CNRS, IPMC, Valbonne, France
| | - Maria Capovilla
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France.,CNRS LIA (Neogenex), Valbonne, France
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20
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Clatworthy AE, Romano KP, Hung DT. Whole-organism phenotypic screening for anti-infectives promoting host health. Nat Chem Biol 2018; 14:331-341. [PMID: 29556098 PMCID: PMC9843822 DOI: 10.1038/s41589-018-0018-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 11/20/2017] [Indexed: 01/19/2023]
Abstract
To date, antibiotics have been identified on the basis of their ability to kill bacteria or inhibit their growth rather than directly for their capacity to improve clinical outcomes of infected patients. Although historically successful, this approach has led to the development of an antibiotic armamentarium that suffers from a number of shortcomings, including the inevitable emergence of resistance and, in certain infections, suboptimal efficacy leading to long treatment durations, infection recurrence, or high mortality and morbidity rates despite apparent bacterial sterilization. Conventional antibiotics fail to address the complexities of in vivo bacterial physiology and virulence, as well as the role of the host underlying the complex, dynamic interactions that cause disease. New interventions are needed, aimed at host outcome rather than microbiological cure. Here we review the role of screening models for cellular and whole-organism infection, including worms, flies, zebrafish, and mice, to identify novel therapeutic strategies and discuss their future implications.
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Affiliation(s)
- Anne E. Clatworthy
- Broad Institute of MIT and Harvard, Cambridge, MA, USA,Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Keith P. Romano
- Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA,Division of Pulmonary and Critical Care Medicine, Brigham and Women’s Hospital, Boston, MA, USA
| | - Deborah T. Hung
- Broad Institute of MIT and Harvard, Cambridge, MA, USA,Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, USA,Department of Genetics, Harvard Medical School, Boston, MA, USA,Correspondence and requests for materials should be addressed to D.T.H.
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Lo Piccolo L. Drosophila as a Model to Gain Insight into the Role of lncRNAs in Neurological Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1076:119-146. [PMID: 29951818 DOI: 10.1007/978-981-13-0529-0_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It is now clear that the majority of transcription in humans results in the production of long non-protein-coding RNAs (lncRNAs) with a variable length spanning from 200 bp up to several kilobases. To date, we have a limited understanding of the lncRNA function, but a huge number of evidences have suggested that lncRNAs represent an outstanding asset for cells. In particular, temporal and spatial expression of lncRNAs appears to be important for proper neurological functioning. Stunningly, abnormal lncRNA function has been found as being critical for the onset of neurological disorders. This chapter focus on the lncRNAs with a role in diseases affecting the central nervous system with particular regard for the lncRNAs causing those neurodegenerative diseases that exhibit dementia and/or motor dysfunctions. A specific section will be dedicated to the human neuronal lncRNAs that have been modelled in Drosophila. Finally, even if only few examples have been reported so far, an overview of the Drosophila lncRNAs with neurological functions will be also included in this chapter.
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Affiliation(s)
- Luca Lo Piccolo
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine 2-2 Yamadaoka, Suita Osaka, 565-0871, Japan.
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22
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Kong HE, Zhao J, Xu S, Jin P, Jin Y. Fragile X-Associated Tremor/Ataxia Syndrome: From Molecular Pathogenesis to Development of Therapeutics. Front Cell Neurosci 2017; 11:128. [PMID: 28529475 PMCID: PMC5418347 DOI: 10.3389/fncel.2017.00128] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/18/2017] [Indexed: 12/31/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by a premutation CGG repeat expansion (55-200 repeats) within the 5' UTR of the fragile X gene (FMR1). FXTAS is characterized by intension tremor, cerebellar ataxia, progressive neurodegeneration, parkinsonism and cognitive decline. The development of transgenic mouse and Drosophila melanogaster models carrying an expanded CGG repeat has yielded valuable insight into the pathophysiology of FXTAS. To date, we know of two main molecular mechanisms of this disorder: (1) a toxic gain of function of the expanded CGG-repeat FMR1 mRNA, which results in the binding/sequestration of the CGG-binding proteins; and (2) CGG repeat-associated non-AUG-initiated (RAN) translation, which generates a polyglycine peptide toxic to cells. Besides these CGG-mediated mechanisms, recent studies have shed light on additional mechanisms of pathogenesis, such as the antisense transcript ASFMR1, mitochondrial dysfunction, DNA damage from R-loop formation and 5-hydroxymethylcytosine (5hmC)-mediated epigenetic modulation. Here we summarize the recent progress towards understanding the etiology of FXTAS and provide an overview of potential treatment strategies.
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Affiliation(s)
- Ha Eun Kong
- Department of Human Genetics, School of Medicine, Emory UniversityAtlanta, GA, USA
| | - Juan Zhao
- The State Key Laboratory of Medical Genetics, School of Life Sciences, Central South UniversityChangsha, China
| | - Shunliang Xu
- Department of Neurology, 2nd Hospital of Shandong UniversityJinan, China
| | - Peng Jin
- Department of Human Genetics, School of Medicine, Emory UniversityAtlanta, GA, USA
| | - Yan Jin
- Department of Ophthalmology, Second Hospital, Jilin UniversityChangchun, China
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Abstract
The main goal of this paper is to present the case for shifting the focus of research on aging and anti-aging from lifespan pharmacology to what I like to call healthspan pharmacology, in which the desired outcome is the extension of healthy years of life rather than lifespan alone. Lifespan could be influenced by both genetic and epigenetic factors, but a long lifespan may not be a good indicator of an optimal healthspan. Without improving healthspan, prolonging longevity would have enormous negative socioeconomic outcomes for humans. Therefore, the goal of aging and anti-aging research should be to add healthy years to life and not merely to increase the chronological age. This article summarizes and compares two categories of pharmacologically induced lifespan extension studies in animal model systems from the last two decades-those reporting the effects of pharmacological interventions on lifespan extension alone versus others that include their effects on both lifespan and healthspan in the analysis. The conclusion is that the extrapolation of pharmacological results from animal studies to humans is likely to be more relevant when both lifespan and healthspan extension properties of pharmacological intervention are taken into account.
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Affiliation(s)
- Mahtab Jafari
- Department of Pharmaceutical Sciences, University of California Irvine , Irvine, California
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Hanus J, Kolkin A, Chimienti J, Botsay S, Wang S. 4-Acetoxyphenol Prevents RPE Oxidative Stress-Induced Necrosis by Functioning as an NRF2 Stabilizer. Invest Ophthalmol Vis Sci 2015; 56:5048-59. [PMID: 26241392 DOI: 10.1167/iovs.15-16401] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Oxidative stress has been suggested to be a major risk factor for the pathogenesis of AMD. Retinal pigment epithelial (RPE) cells are essential for maintaining the homeostasis of the retina, and RPE cell death and the resultant photoreceptor apoptosis have been observed in dry AMD, especially in geographic atrophy. The purpose of this article was to identify and repurpose the Food and Drug Administration-approved natural compound 4-Acetoxyphenol (4-AC), and to evaluate its effect and mechanism in protecting against oxidative stress-induced RPE necrosis. METHODS We exposed ARPE-19 cells to tert-Butyl hydroperoxide (tBHP) after pretreatment with 4-AC, and measured cell viability by MTT assay. Aggregation of RIPK3 and HMGB1 nuclear release were analyzed by transfected reporter genes. Reactive oxygen species (ROS) were measured using a commercially available ROS detection system. The importance of the NRF2/NQO1/HO-1 pathway in mediating 4-AC function was corroborated by siRNA studies, qRT-PCR, and immunostaining. RESULTS We have identified a natural antioxidant, 4-AC, which demonstrates strong abilities to protect RPE cells from oxidative stress-induced necrosis. Mechanistically, 4-AC blocked the increase of cellular ROS induced by oxidative stress, and upregulated NQO1 and HO-1 genes by stabilizing and inducing the nuclear translocation of NRF2 transcription factor. The NQO1, HO-1, and NRF2 were further shown to be required for 4-AC protection of RPE cells from death induced by tBHP. The tBHQ, an NRF2 stabilizer, consistently mimicked the protective effect of 4-AC against tBHP-induced RPE death. CONCLUSIONS The compound 4-AC protects ARPE-19 cells from oxidative stress-induced necrosis through upregulation of NQO1 and HO-1 genes by stabilization of NRF2.
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Affiliation(s)
- Jakub Hanus
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, United States
| | - Alexander Kolkin
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, United States
| | - Julia Chimienti
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, United States
| | - Sara Botsay
- Southern Eye Bank, Metairie, Louisiana, United States
| | - Shusheng Wang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana, United States 3Department of Ophthalmology, Tulane University, New Orleans, Louisiana, United States
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Plantié E, Migocka-Patrzałek M, Daczewska M, Jagla K. Model organisms in the fight against muscular dystrophy: lessons from drosophila and Zebrafish. Molecules 2015; 20:6237-53. [PMID: 25859781 PMCID: PMC6272363 DOI: 10.3390/molecules20046237] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 01/01/2023] Open
Abstract
Muscular dystrophies (MD) are a heterogeneous group of genetic disorders that cause muscle weakness, abnormal contractions and muscle wasting, often leading to premature death. More than 30 types of MD have been described so far; those most thoroughly studied are Duchenne muscular dystrophy (DMD), myotonic dystrophy type 1 (DM1) and congenital MDs. Structurally, physiologically and biochemically, MDs affect different types of muscles and cause individual symptoms such that genetic and molecular pathways underlying their pathogenesis thus remain poorly understood. To improve our knowledge of how MD-caused muscle defects arise and to find efficacious therapeutic treatments, different animal models have been generated and applied. Among these, simple non-mammalian Drosophila and zebrafish models have proved most useful. This review discusses how zebrafish and Drosophila MD have helped to identify genetic determinants of MDs and design innovative therapeutic strategies with a special focus on DMD, DM1 and congenital MDs.
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Affiliation(s)
- Emilie Plantié
- GReD (Genetics, Reproduction and Development laboratory), INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France; E-Mail:
| | - Marta Migocka-Patrzałek
- Department of Animal Developmental Biology, Institute of Experimental Biology, University of Wroclaw, 21 Sienkiewicza Street, 50-335 Wroclaw, Poland; E-Mails: (M.M.-P.); (M.D.)
| | - Małgorzata Daczewska
- Department of Animal Developmental Biology, Institute of Experimental Biology, University of Wroclaw, 21 Sienkiewicza Street, 50-335 Wroclaw, Poland; E-Mails: (M.M.-P.); (M.D.)
| | - Krzysztof Jagla
- GReD (Genetics, Reproduction and Development laboratory), INSERM U1103, CNRS UMR6293, University of Clermont-Ferrand, 28 place Henri-Dunant, 63000 Clermont-Ferrand, France; E-Mail:
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Gossypol Acetic Acid Prevents Oxidative Stress-Induced Retinal Pigment Epithelial Necrosis by Regulating the FoxO3/Sestrin2 Pathway. Mol Cell Biol 2015; 35:1952-63. [PMID: 25802279 DOI: 10.1128/mcb.00178-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 03/15/2015] [Indexed: 02/04/2023] Open
Abstract
The late stage of dry age-related macular degeneration (AMD), or geographic atrophy (GA), is characterized by extensive retinal pigment epithelial (RPE) cell death, and a cure is not available currently. We have recently demonstrated that RPE cells die from necrosis in response to oxidative stress, providing a potential novel mechanism for RPE death in AMD. In this study, we screened U.S. Food and Drug Administration-approved natural compounds and identified gossypol acetic acid (GAA) as a potent inhibitor of oxidative stress-induced RPE cell death. GAA induces antioxidative response and inhibits accumulation of excessive reactive oxygen species in cells, through which it prevents the activation of intrinsic necrotic pathway in response to oxidative stress. Sestrin2 (SESN2) is found to mediate GAA function in antioxidative response and RPE survival upon oxidative stress. Moreover, Forkhead box O3 transcription factor (FoxO3) is further found to be required for GAA-mediated SESN2 expression and RPE survival. Mechanistically, GAA promotes FoxO3 nuclear translocation and binding to the SESN2 enhancer, which in turn increases its transcriptional activity. Taken together, we have identified GAA as a potent inhibitor of oxidative stress-induced RPE necrosis by regulating the FoxO3/SESN2 pathway. This study may have significant implications in the therapeutics of age-related diseases, especially GA.
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Inhibition of transglutaminase exacerbates polyglutamine-induced neurotoxicity by increasing the aggregation of mutant ataxin-3 in an SCA3 Drosophila model. Neurotox Res 2014; 27:259-67. [PMID: 25501875 DOI: 10.1007/s12640-014-9506-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 11/14/2014] [Accepted: 12/01/2014] [Indexed: 01/24/2023]
Abstract
Transglutaminases (TGs) comprise a family of Ca(2+)-dependent enzymes that catalyze protein cross-linking, which include nine family members in humans but only a single homolog in Drosophila with three conserved domains. Drosophila Tg plays important roles in cuticle morphogenesis, hemolymph clotting, and innate immunity. Mammalian tissue TG (TG2) is involved in polyglutamine diseases (polyQ diseases), and TG6 has been identified as a causative gene of a novel spinocerebellar ataxia, SCA35. Using a well-established SCA3 fly model, we found that RNA interference-mediated suppression of Tg aggravated polyQ-induced neurodegenerative phenotypes. The administration of cystamine, a known effective Tg inhibitor, enhanced ommatidial degeneration in SCA3 flies. We also demonstrated that the aggregates of pathogenic ataxin-3 increased greatly, when the Tg activity was repressed. These findings indicate that Tg is crucial for polyQ-induced neurotoxicity because Tg ablation resulted in more severe neurodegeneration due to the elevated accumulation of insoluble ataxin-3 complexes in the SCA3 Drosophila model.
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Memantine effects on verbal memory in fragile X-associated tremor/ataxia syndrome (FXTAS): a double-blind brain potential study. Neuropsychopharmacology 2014; 39:2760-8. [PMID: 24871547 PMCID: PMC4200486 DOI: 10.1038/npp.2014.122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/29/2014] [Accepted: 05/08/2014] [Indexed: 12/19/2022]
Abstract
Older FMR1 premutation carriers may develop fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder manifesting cognitive deficits that often subsequently progress to dementia. To date, there is no specific treatment available for FXTAS. Studies have demonstrated the premutation-associated overactivation of glutamatergic receptors in neurons. Memantine, a NMDA receptor antagonist approved for treatment of Alzheimer's disease, thus was tested in the first placebo-controlled, double-blind, randomized clinical trial in FXTAS. Prior event-related brain potential (ERP) studies in FXTAS found reduced N400 repetition effect, a glutamate-related electrophysiological marker of semantic priming, and verbal memory processes. This substudy of the randomized clinical trial of memantine in FXTAS sought to use the N400 repetition effect to evaluate effects of chronic memantine treatment on verbal memory. Subsequent recall and recognition memory tests for the experimental stimuli were administered to characterize verbal memory. Data from 41 patients who completed the 1-year memantine trial (21 on memantine) and also completed longitudinal ERP studies were analyzed. Results showed treatment-associated benefits on both cued-recall memory and N400 repetition effect amplitude. Importantly, improvement in cued recall was positively correlated with amplitude increase of the N400 repetition effect. The placebo group, in contrast, displayed a significant reduction of the N400 repetition effect after 1 year. These results suggest that memantine treatment may have beneficial effects on verbal memory in FXTAS. Additional studies of memantine, perhaps in combination with other therapeutic agents, appear warranted, as symptomatic treatments and neuroprotective treatments are both needed for this recently recognized neurodegenerative disorder.
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29
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Combating neurodegenerative disease with chemical probes and model systems. Nat Chem Biol 2014; 10:911-20. [PMID: 25325702 DOI: 10.1038/nchembio.1663] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/11/2014] [Indexed: 12/19/2022]
Abstract
The disheartening results of recent clinical trials for neurodegenerative disease (ND) therapeutics underscore the need for a more comprehensive understanding of the underlying disease biology before effective therapies can be devised. One hallmark of many NDs is a disruption in protein homeostasis. Therefore, investigating the role of protein homeostasis in these diseases is central to delineating their underlying pathobiology. Here, we review the seminal role that chemical biology has played in furthering the research on and treatment of dysfunctional protein homeostasis in NDs. We also discuss the vital and predictive role of model systems in identifying conserved homeostasis pathways and genes therein that are altered in neurodegeneration. Integrating approaches from chemical biology with the use of model systems yields a powerful toolkit with which to unravel the complexities of ND biology.
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30
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Galloway JN, Shaw C, Yu P, Parghi D, Poidevin M, Jin P, Nelson DL. CGG repeats in RNA modulate expression of TDP-43 in mouse and fly models of fragile X tremor ataxia syndrome. Hum Mol Genet 2014; 23:5906-15. [PMID: 24986919 DOI: 10.1093/hmg/ddu314] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Determining the molecular mechanism(s) leading to Purkinje neuron loss in the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS) is limited by the complex morphology of this cell type. Purkinje neurons are notoriously difficult to isolate and maintain in culture presenting considerable difficultly to identify molecular changes in response to expanded CGG repeat (rCGG)-containing mRNA that induces neurotoxicity in FXTAS. Several studies have uncovered a number of RNA-binding proteins involved in translation that aberrantly interact with the CGG-containing RNA; however, whether these interactions alter the translational profile of cells has not been investigated. Here we employ bacTRAP translational profiling to demonstrate that Purkinje neurons ectopically expressing 90 CGG repeats exhibit a dramatic change in their translational profile even prior to the onset of rCGG-induced phenotypes. This approach identified ∼500 transcripts that are differentially associated with ribosomes in r(CGG)₉₀-expressing mice. Functional annotation cluster analysis revealed broad ontologies enriched in the r(CGG)₉₀ list, including RNA binding and response to stress. Intriguingly, a transcript for the Tardbp gene, implicated in a number of other neurodegenerative disorders, exhibits altered association with ribosomes in the presence of r(CGG)₉₀ repeats. We therefore tested and showed that reduced association of Tardbp mRNA with the ribosomes results in a loss of TDP-43 protein expression in r(CGG)₉₀-expressing Purkinje neurons. Furthermore, we showed that TDP-43 could modulate the rCGG repeat-mediated toxicity in a Drosophila model that we developed previously. These findings together suggest that translational dysregulation may be an underlying mechanism of rCGG-induced neurotoxicity in FXTAS.
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Affiliation(s)
| | - Chad Shaw
- Department of Human and Molecular Genetics and
| | - Peng Yu
- Department of Human and Molecular Genetics and
| | - Deena Parghi
- Department of Pathology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA and
| | - Mickael Poidevin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - David L Nelson
- Interdepartmental Program in Cell and Molecular Biology, Department of Human and Molecular Genetics and
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Wairkar YP, Trivedi D, Natarajan R, Barnes K, Dolores L, Cho P. CK2α regulates the transcription of BRP in Drosophila. Dev Biol 2013; 384:53-64. [PMID: 24080510 DOI: 10.1016/j.ydbio.2013.09.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 09/18/2013] [Accepted: 09/20/2013] [Indexed: 01/26/2023]
Abstract
Development and plasticity of synapses are brought about by a complex interplay between various signaling pathways. Typically, either changing the number of synapses or strengthening an existing synapse can lead to changes during synaptic plasticity. Altering the machinery that governs the exocytosis of synaptic vesicles, which primarily fuse at specialized structures known as active zones on the presynaptic terminal, brings about these changes. Although signaling pathways that regulate the synaptic plasticity from the postsynaptic compartments are well defined, the pathways that control these changes presynaptically are poorly described. In a genetic screen for synapse development in Drosophila, we found that mutations in CK2α lead to an increase in the levels of Bruchpilot (BRP), a scaffolding protein associated with the active zones. Using a combination of genetic and biochemical approaches, we found that the increase in BRP in CK2α mutants is largely due to an increase in the transcription of BRP. Interestingly, the transcripts of other active zone proteins that are important for function of active zones were also increased, while the transcripts from some other synaptic proteins were unchanged. Thus, our data suggest that CK2α might be important in regulating synaptic plasticity by modulating the transcription of BRP. Hence, we propose that CK2α is a novel regulator of the active zone protein, BRP, in Drosophila.
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Affiliation(s)
- Yogesh P Wairkar
- Department of Neurology, Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, 301 University Blvd., Rte#1045, Galveston, TX 77555, United States.
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Lin Y, Tang C, He H, Duan R. Activation of mTOR ameliorates fragile X premutation rCGG repeat-mediated neurodegeneration. PLoS One 2013; 8:e62572. [PMID: 23626835 PMCID: PMC3633886 DOI: 10.1371/journal.pone.0062572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 03/23/2013] [Indexed: 01/25/2023] Open
Abstract
Fragile X associated tremor/ataxia syndrome (FXTAS) is a late onset neurodegenerative disorder caused by aberrant expansion of CGG repeats in 5′ UTR of FMR1 gene. The elevated mRNA confers a toxic gain-of-function thought to be the critical event of pathogenesis. Expressing rCGG90 repeats of the human FMR1 5′UTR in Drosophila is sufficient to induce neurodegeneration. Rapamycin has been demonstrated to attenuate neurotoxicity by inducing autophagy in various animal models of neurodegenerative diseases. Surprisingly, we observed rapamycin exacerbated rCGG90-induced neurodegenerative phenotypes through an autophagy-independent mechanism. CGG90 expression levels of FXTAS flies exposed to rapamycin presented no significant differences. We further demonstrated that activation of the mammalian target of rapamycin (mTOR) signaling could suppress neurodegeneration of FXTAS. These findings indicate that rapamycin will exacerbate neurodegeneration, and that enhancing autophagy is insufficient to alleviate neurotoxicity in FXTAS. Moreover, these results suggest mTOR and its downstream molecules as new therapeutic targets for FXTAS by showing significant protection against neurodegeneration.
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Affiliation(s)
- Yunting Lin
- The State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan, China
| | - Chengyuan Tang
- The State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan, China
| | - Hua He
- The State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan, China
| | - Ranhui Duan
- The State Key Laboratory of Medical Genetics, Xiangya Medical School, Central South University, Changsha, Hunan, China
- * E-mail:
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Nelson DL, Orr HT, Warren ST. The unstable repeats--three evolving faces of neurological disease. Neuron 2013; 77:825-43. [PMID: 23473314 PMCID: PMC3608403 DOI: 10.1016/j.neuron.2013.02.022] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2013] [Indexed: 01/08/2023]
Abstract
Disorders characterized by expansion of an unstable nucleotide repeat account for a number of inherited neurological diseases. Here, we review examples of unstable repeat disorders that nicely illustrate three of the major pathogenic mechanisms associated with these diseases: loss of function typically by disrupting transcription of the mutated gene, RNA toxic gain of function, and protein toxic gain of function. In addition to providing insight into the mechanisms underlying these devastating neurological disorders, the study of these unstable microsatellite repeat disorders has provided insight into very basic aspects of neuroscience.
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Affiliation(s)
- David L. Nelson
- Department of Molecular and Human Genetics, Baylor College
of Medicine, Houston, TX 77030
- Correspondance:
(D.L.N.), (H.T.O.),
(S.T.W.)
| | - Harry T. Orr
- Department of Laboratory Medicine and Pathology, University
of Minnesota, Minneapolis, MN 55455
- Correspondance:
(D.L.N.), (H.T.O.),
(S.T.W.)
| | - Stephen T. Warren
- Department of Human Genetics, Emory University School of
Medicine, Atlanta, GA 30322
- Correspondance:
(D.L.N.), (H.T.O.),
(S.T.W.)
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Zongaro S, Hukema R, D'Antoni S, Davidovic L, Barbry P, Catania MV, Willemsen R, Mari B, Bardoni B. The 3' UTR of FMR1 mRNA is a target of miR-101, miR-129-5p and miR-221: implications for the molecular pathology of FXTAS at the synapse. Hum Mol Genet 2013; 22:1971-82. [PMID: 23390134 DOI: 10.1093/hmg/ddt044] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
While FMR1 is silenced in Fragile X syndrome (FXS) patients carrying the full mutation, its expression is elevated (2-8 fold) in premutated individuals. These people may develop the Fragile X-associated Tremor/Ataxia syndrome (FXTAS), a late onset neurodegenerative disorder characterized by ataxia and parkinsonism. In addition, people carrying the premutation can be affected by a set of neurological and behavioral disorders during young age. Problems of memory have been detected in these patients as well as in the mouse models for FXTAS. To date little is known concerning the metabolism of FMR1 mRNA, notwithstanding the importance of the finely tuned regulation of the expression of this gene. In the present study, we identified three microRNAs that specifically target the 3' UTR of FMR1 and can modulate its expression throughout the brain particularly at the synapse where their expression is very high. The expression level of miR-221 is reduced in synaptosomal preparations of young FXTAS mice suggesting a general deregulation of transcripts located at the synapse of these mice. By transcriptome analysis, we show here a robust deregulation of the expression levels of genes involved in learning, memory and autistic behavior, Parkinson disease and neurodegeneration. These findings suggest the presence of a synaptopathy in these animals. Interestingly, many of those deregulated mRNAs are target of the same microRNAs that modulate the expression of FMR1 at the synapse.
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Affiliation(s)
- Samantha Zongaro
- CNRS UMR 7275, Institute of Molecular and Cellular Pharmacology, Valbonne Sophia-Antipolis, France
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Li Y, Jin P. RNA-mediated neurodegeneration in fragile X-associated tremor/ataxia syndrome. Brain Res 2012; 1462:112-7. [PMID: 22459047 DOI: 10.1016/j.brainres.2012.02.057] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 11/17/2022]
Abstract
Carriers of fragile X syndrome (FXS) have FMR1 alleles, called premutations, with a number of 5'-untranslated-CGG repeats somewhere between patients, who have over 200 repeats, and normal individuals, with fewer than 60 repeats. Fragile X-associated tremor/ataxia syndrome (FXTAS), a late-onset neurodegenerative disorder, has been recognized in older male fragile X premutation carriers, and FXTAS is uncoupled from the neurodevelopmental disorder, FXS. Several lines of evidence have led to the proposal of an RNA (fragile X premutation rCGG repeat)-mediated gain-of-function toxicity model for FXTAS, in which rCGG repeat-binding proteins (RBPs) could become functionally limited by their sequestration to lengthy rCGG repeats. In this review, we will discuss the recent progress towards understanding the molecular basis of RNA-mediated neurodegeneration in FXTAS. This article is part of a Special Issue entitled: RNA-Binding Proteins.
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Affiliation(s)
- Yujing Li
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
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