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Rodden LN, Rummey C, Kessler S, Wilson RB, Lynch DR. A Novel Metric for Predicting Severity of Disease Features in Friedreich's Ataxia. Mov Disord 2023. [PMID: 36928898 DOI: 10.1002/mds.29370] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 01/25/2023] [Accepted: 02/16/2023] [Indexed: 03/18/2023] Open
Abstract
BACKGROUND Friedreich's ataxia (FRDA), most commonly caused by a GAA triplet repeat (GAA-TR) expansion in intron 1 of the FXN gene, is characterized by deficiency of frataxin protein and clinical features such as progressive ataxia, dysarthria, impaired proprioception and vibration, abolished deep tendon reflexes, Babinski sign, and vision loss in association with non-neurological features such as skeletal anomalies, hearing loss, cardiomyopathy, and diabetes. Pathogenic GAA-TRs range in size from 60 to 1500 triplets and negatively correlate with age of onset. Clinical severity is predicted by a combination of GAA-TR length and disease duration (DD) via multivariable regressions, which cannot typically be used for the small sample sizes in most studies on this rare disease. OBJECTIVE We aimed to develop a single metric, which we call "disease burden" (DB), that encompasses both GAA-TR length and DD for predicting disease features of FRDA in small sample sizes. METHODS Linear regression and multivariable regression analysis was used to determine correlation coefficients between different disease features of FRDA. RESULTS Using large datasets for validation, we found that DB predicts measures of neurological dysfunction in FRDA better than GAA-TR length or DD. Analogous results were found using small datasets. CONCLUSIONS FRDA DB is a novel metric of disease severity that has utility in small datasets to demonstrate correlations that would not otherwise be evident with either GAA-TR or DD alone. This is important for discovering new biomarkers, as well as improving the prediction of severity of disease features in FRDA. © 2023 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Layne N Rodden
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Sudha Kessler
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert B Wilson
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David R Lynch
- Departments of Pediatrics and Neurology, Children's Hospital of Philadelphia, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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2
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Wang D, Ho ES, Cotticelli MG, Xu P, Napierala JS, Hauser LA, Napierala M, Himes BE, Wilson RB, Lynch DR, Mesaros C. Skin fibroblast metabolomic profiling reveals that lipid dysfunction predicts the severity of Friedreich's ataxia. J Lipid Res 2022; 63:100255. [PMID: 35850241 PMCID: PMC9399481 DOI: 10.1016/j.jlr.2022.100255] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 12/26/2022] Open
Abstract
Friedreich's ataxia (FRDA) is an autosomal recessive neurodegenerative disorder caused by a triplet guanine-adenine-adenine (GAA) repeat expansion in intron 1 of the FXN gene, which leads to decreased levels of the frataxin protein. Frataxin is involved in the formation of iron-sulfur (Fe-S) cluster prosthetic groups for various metabolic enzymes. To provide a better understanding of the metabolic status of patients with FRDA, here we used patient-derived fibroblast cells as a surrogate tissue for metabolic and lipidomic profiling by liquid chromatography-high resolution mass spectrometry. We found elevated HMG-CoA and β-hydroxybutyrate-CoA levels, implying dysregulated fatty acid oxidation, which was further demonstrated by elevated acyl-carnitine levels. Lipidomic profiling identified dysregulated levels of several lipid classes in FRDA fibroblast cells when compared with non-FRDA fibroblast cells. For example, levels of several ceramides were significantly increased in FRDA fibroblast cells; these results positively correlated with the GAA repeat length and negatively correlated with the frataxin protein levels. Furthermore, stable isotope tracing experiments indicated increased ceramide synthesis, especially for long-chain fatty acid-ceramides, in FRDA fibroblast cells compared with ceramide synthesis in healthy control fibroblast cells. In addition, PUFA-containing triglycerides and phosphatidylglycerols were enriched in FRDA fibroblast cells and negatively correlated with frataxin levels, suggesting lipid remodeling as a result of FXN deficiency. Altogether, we demonstrate patient-derived fibroblast cells exhibited dysregulated metabolic capabilities, and their lipid dysfunction predicted the severity of FRDA, making them a useful surrogate to study the metabolic status in FRDA.
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Affiliation(s)
- Dezhen Wang
- Center for Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Elaine S. Ho
- Center for Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - M. Grazia Cotticelli
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Peining Xu
- Center for Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jill S. Napierala
- University of Alabama at Birmingham, Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, Birmingham, Alabama, USA
| | - Lauren A. Hauser
- Department of Neurology and Pediatrics, Children’s Hospital of Philadelphia, Abramson Research, Philadelphia, Pennsylvania, USA
| | - Marek Napierala
- University of Alabama at Birmingham, Department of Biochemistry and Molecular Genetics, UAB Stem Cell Institute, Birmingham, Alabama, USA
| | - Blanca E. Himes
- Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert B. Wilson
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - David R. Lynch
- Department of Neurology and Pediatrics, Children’s Hospital of Philadelphia, Abramson Research, Philadelphia, Pennsylvania, USA
| | - Clementina Mesaros
- Center for Excellence in Environmental Toxicology, Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania, USA,For correspondence: Clementina Mesaros
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3
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Kong HE, Pollack BP. Cutaneous findings in myotonic dystrophy. JAAD Int 2022; 7:7-12. [PMID: 35243403 PMCID: PMC8867117 DOI: 10.1016/j.jdin.2021.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 11/06/2022] Open
Abstract
Myotonic dystrophy types 1 and 2 are a group of complex genetic disorders resulting from the expansion of (CTG)n nucleotide repeats in the DMPK gene. In addition to the hallmark manifestations of myotonia and skeletal muscle atrophy, myotonic dystrophy also affects a myriad of other organs including the heart, lungs, as well as the skin. The most common cutaneous manifestations of myotonic dystrophy are early male frontal alopecia and adult-onset pilomatricomas. Myotonic dystrophy also increases the risk of developing malignant skin diseases such as basal cell carcinoma and melanoma. To aid in the diagnosis and treatment of myotonic dystrophy related skin conditions, it is important for the dermatologist to become cognizant of the common and rare cutaneous manifestations of this genetic disorder. We performed a PubMed search using the key terms “myotonic dystrophy” AND “cutaneous” OR “skin” OR “dermatologic” AND “manifestation” OR “finding.” The resulting publications were manually reviewed for additional relevant publications, and subsequent additional searches were performed as needed, especially regarding the molecular mechanisms of pathogenesis. In this review, we aim to provide an overview of myotonic dystrophy types 1 and 2 and summarize their cutaneous manifestations as well as potential mechanisms of pathogenesis.
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Affiliation(s)
- Ha Eun Kong
- Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia
| | - Brian P Pollack
- Atlanta VA Health System, Decatur, Georgia.,Department of Dermatology, Emory University School of Medicine, Atlanta, Georgia.,Department of Pathology, Emory University School of Medicine, Atlanta, Georgia.,Winship Cancer Institute of Emory University School of Medicine, Atlanta, Georgia
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4
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Williams GM, Paschalis V, Ortega J, Muskett FW, Hodgkinson JT, Li GM, Schwabe JWR, Lahue RS. HDAC3 deacetylates the DNA mismatch repair factor MutSβ to stimulate triplet repeat expansions. Proc Natl Acad Sci U S A 2020; 117:23597-605. [PMID: 32900932 DOI: 10.1073/pnas.2013223117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Trinucleotide repeat (TNR) expansions cause nearly 20 severe human neurological diseases which are currently untreatable. For some of these diseases, ongoing somatic expansions accelerate disease progression and may influence age of onset. This new knowledge emphasizes the importance of understanding the protein factors that drive expansions. Recent genetic evidence indicates that the mismatch repair factor MutSβ (Msh2-Msh3 complex) and the histone deacetylase HDAC3 function in the same pathway to drive triplet repeat expansions. Here we tested the hypothesis that HDAC3 deacetylates MutSβ and thereby activates it to drive expansions. The HDAC3-selective inhibitor RGFP966 was used to examine its biological and biochemical consequences in human tissue culture cells. HDAC3 inhibition efficiently suppresses repeat expansion without impeding canonical mismatch repair activity. Five key lysine residues in Msh3 are direct targets of HDAC3 deacetylation. In cells expressing Msh3 in which these lysine residues are mutated to arginine, the inhibitory effect of RGFP966 on expansions is largely bypassed, consistent with the direct deacetylation hypothesis. RGFP966 treatment does not alter MutSβ subunit abundance or complex formation but does partially control its subcellular localization. Deacetylation sites in Msh3 overlap a nuclear localization signal, and we show that localization of MutSβ is partially dependent on HDAC3 activity. Together, these results indicate that MutSβ is a key target of HDAC3 deacetylation and provide insights into an innovative regulatory mechanism for triplet repeat expansions. The results suggest expansion activity may be druggable and support HDAC3-selective inhibition as an attractive therapy in some triplet repeat expansion diseases.
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5
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Ausems CRM, Raaijmakers RHL, van den Broek WJAA, Willemse M, van Engelen BGM, Wansink DG, van Bokhoven H. Intrinsic Myogenic Potential of Skeletal Muscle-Derived Pericytes from Patients with Myotonic Dystrophy Type 1. Mol Ther Methods Clin Dev 2019; 15:120-132. [PMID: 31649961 PMCID: PMC6804802 DOI: 10.1016/j.omtm.2019.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 09/04/2019] [Indexed: 12/21/2022]
Abstract
Pericytes are multipotent, vessel-associated progenitors that exhibit high proliferative capacity, can cross the blood-muscle barrier, and have the ability to home to muscle tissue and contribute to myogenesis. Consequently, pericyte-based therapies hold great promise for muscular dystrophies. A complex multi-system disorder exhibiting muscular dystrophy for which pericytes might be a valuable cell source is myotonic dystrophy type 1 (DM1). DM1 is caused by an unstable (CTG)n repeat in the DMPK gene and characterized by skeletal muscle weakness, muscle wasting, and myotonia. We have successfully isolated alkaline phosphatase-positive pericytes from skeletal muscle of DM1 patients and a transgenic mouse model. Intranuclear (CUG)n RNA foci, a pathogenic DM1 hallmark, were identified in human and mouse pericytes. Notably, pericytes from DM1 patients maintained similar growth parameters and innate myogenic characteristics in vitro compared to cells from unaffected controls. Our in vitro results thus demonstrate the potential of pericytes to ameliorate muscle features in DM1 in a therapeutic setting.
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Affiliation(s)
- Cornelia Rosanne Maria Ausems
- Department of Human Genetics, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6525 GA Nijmegen, the Netherlands.,Department of Neurology, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6500 HB Nijmegen, the Netherlands.,Department of Cell Biology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6525 GA Nijmegen, the Netherlands
| | - Renée Henrica Lamberta Raaijmakers
- Department of Human Genetics, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6525 GA Nijmegen, the Netherlands.,Department of Neurology, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6500 HB Nijmegen, the Netherlands.,Department of Cell Biology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6525 GA Nijmegen, the Netherlands
| | | | - Marieke Willemse
- Department of Cell Biology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6525 GA Nijmegen, the Netherlands
| | - Baziel Gerardus Maria van Engelen
- Department of Neurology, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6500 HB Nijmegen, the Netherlands
| | - Derick Gert Wansink
- Department of Cell Biology, Radboud University Medical Center, Radboud Institute for Molecular Life Sciences, 6525 GA Nijmegen, the Netherlands
| | - Hans van Bokhoven
- Department of Human Genetics, Radboud University Medical Center, Donders lnstitute for Brain Cognition and Behavior, 6525 GA Nijmegen, the Netherlands
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Eimer H, Sureshkumar S, Singh Yadav A, Kraupner-Taylor C, Bandaranayake C, Seleznev A, Thomason T, Fletcher SJ, Gordon SF, Carroll BJ, Balasubramanian S. RNA-Dependent Epigenetic Silencing Directs Transcriptional Downregulation Caused by Intronic Repeat Expansions. Cell 2018; 174:1095-1105.e11. [PMID: 30057112 DOI: 10.1016/j.cell.2018.06.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 04/20/2018] [Accepted: 06/22/2018] [Indexed: 01/07/2023]
Abstract
Transcriptional downregulation caused by intronic triplet repeat expansions underlies diseases such as Friedreich's ataxia. This downregulation of gene expression is coupled with epigenetic changes, but the underlying mechanisms are unknown. Here, we show that an intronic GAA/TTC triplet expansion within the IIL1 gene of Arabidopsis thaliana results in accumulation of 24-nt short interfering RNAs (siRNAs) and repressive histone marks at the IIL1 locus, which in turn causes its transcriptional downregulation and an associated phenotype. Knocking down DICER LIKE-3 (DCL3), which produces 24-nt siRNAs, suppressed transcriptional downregulation of IIL1 and the triplet expansion-associated phenotype. Furthermore, knocking down additional components of the RNA-dependent DNA methylation (RdDM) pathway also suppressed both transcriptional downregulation of IIL1 and the repeat expansion-associated phenotype. Thus, our results show that triplet repeat expansions can lead to local siRNA biogenesis, which in turn downregulates transcription through an RdDM-dependent epigenetic modification.
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Affiliation(s)
- Hannes Eimer
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | - Sridevi Sureshkumar
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | - Avilash Singh Yadav
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | | | - Champa Bandaranayake
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | - Andrei Seleznev
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | - Tamblyn Thomason
- School of Biological Sciences, Monash University, Clayton Campus, VIC 3800, Australia
| | - Stephen J Fletcher
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia QLD 4072, Australia
| | | | - Bernard J Carroll
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia QLD 4072, Australia
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Gudde AEEG, van Heeringen SJ, de Oude AI, van Kessel IDG, Estabrook J, Wang ET, Wieringa B, Wansink DG. Antisense transcription of the myotonic dystrophy locus yields low-abundant RNAs with and without (CAG)n repeat. RNA Biol 2017; 14:1374-1388. [PMID: 28102759 PMCID: PMC5711456 DOI: 10.1080/15476286.2017.1279787] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 12/21/2016] [Accepted: 12/30/2016] [Indexed: 12/20/2022] Open
Abstract
The unstable (CTG·CAG)n trinucleotide repeat in the myotonic dystrophy type 1 (DM1) locus is bidirectionally transcribed from genes with terminal overlap. By transcription in the sense direction, the DMPK gene produces various alternatively spliced mRNAs with a (CUG)n repeat in their 3' UTR. Expression in opposite orientation reportedly yields (CAG)n-repeat containing RNA, but both structure and biologic significance of this antisense gene (DM1-AS) are largely unknown. Via a combinatorial approach of computational and experimental analyses of RNA from unaffected individuals and DM1 patients we discovered that DM1-AS spans >6 kb, contains alternative transcription start sites and uses alternative polyadenylation sites up- and downstream of the (CAG)n repeat. Moreover, its primary transcripts undergo alternative splicing, whereby the (CAG)n segment is removed as part of an intron. Thus, in patients a mixture of DM1-AS RNAs with and without expanded (CAG)n repeat are produced. DM1-AS expression appears upregulated in patients, but transcript abundance remains very low in all tissues analyzed. Our data suggest that DM1-AS transcripts belong to the class of long non-coding RNAs. These and other biologically relevant implications for how (CAG)n-expanded transcripts may contribute to DM1 pathology can now be explored experimentally.
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Affiliation(s)
- Anke E. E. G. Gudde
- Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | - Simon J. van Heeringen
- Radboud University, Faculty of Science, Department of Molecular Developmental Biology, Radboud Institute for Molecular Life Sciences, Nijmegen, The Netherlands
| | - Amanda I. de Oude
- Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | | | - Joseph Estabrook
- Department of Molecular Genetics and Microbiology, Center for Neurogenetics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Eric T. Wang
- Department of Molecular Genetics and Microbiology, Center for Neurogenetics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Bé Wieringa
- Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
| | - Derick G. Wansink
- Radboud University Medical Center, Department of Cell Biology, Nijmegen, The Netherlands
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Mootha VV, Hussain I, Cunnusamy K, Graham E, Gong X, Neelam S, Xing C, Kittler R, Petroll WM. TCF4 Triplet Repeat Expansion and Nuclear RNA Foci in Fuchs' Endothelial Corneal Dystrophy. Invest Ophthalmol Vis Sci 2015; 56:2003-11. [PMID: 25722209 DOI: 10.1167/iovs.14-16222] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Expansion of the intronic CTG18.1 triplet repeat locus within TCF4 contributes significant risk to the development of Fuchs' endothelial corneal dystrophy (FECD) in Eurasian populations, but the mechanisms by which the expanded repeats result in degeneration of the endothelium have been hitherto unknown. The purpose of this study was to examine FECD endothelial samples for the presence of RNA nuclear foci, the hallmark of toxic RNA, as well as evidence of haploinsufficiency of TCF4. METHODS Using fluorescence in situ hybridization, we examined for the presence of nuclear RNA foci containing expanded CUG transcripts in corneal endothelial samples from FECD subjects with CTG18.1 expansion. We also examined for any changes in expression levels of TCF4 by quantitative real-time PCR. RESULTS Numerous discrete nuclear RNA foci were identified in endothelial samples of FECD subjects (n = 8) harboring the CTG18.1 expansion, but not in controls lacking the expansion (n = 5) (P = 7.8 × 10(-4)). Percentage of cells with foci in expansion-positive endothelial samples ranged from 33% to 88%. RNA foci were absent in endothelial samples from an FECD subject without CTG18.1 expansion and a subject with endothelial dysfunction without FECD. Expression of the constitutive TCF4 exon encoding the basic helix-loop-helix domain was unaltered with CTG18.1 expansion. CONCLUSIONS Our findings suggest that the RNA nuclear foci are pathognomonic for CTG18.1 expansion-mediated endothelial disease. The RNA nuclear foci have been previously found only in rare neurodegenerative disorders caused by repeat expansions. Our detection of abundant ribonuclear foci in FECD implicates a role for toxic RNA in this common disease.
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Affiliation(s)
- V Vinod Mootha
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States McDermott Center for Human Growth and Development/Center for Human Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Imran Hussain
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Khrishen Cunnusamy
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Eric Graham
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Xin Gong
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Sudha Neelam
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Chao Xing
- McDermott Center for Human Growth and Development/Center for Human Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - Ralf Kittler
- McDermott Center for Human Growth and Development/Center for Human Genetics, University of Texas Southwestern Medical Center, Dallas, Texas, United States
| | - W Matthew Petroll
- Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, United States
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Mohan V, Ahuja YR, Hasan Q. Muscular myopathies other than myotonic dystrophy also associated with (CTG)n expansion at the DMPK locus. J Pediatr Neurosci 2013; 7:175-8. [PMID: 23560000 PMCID: PMC3611902 DOI: 10.4103/1817-1745.106471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Objective: Assess triplet repeat expansion (CTG)n at the ‘dystrophia-myotonica protein kinase’ (DMPK) locus in muscular myopathies to elucidate its role in myopathic symptoms and enable genetic counseling and prenatal diagnosis in families. Methods and Results: Individuals with symptoms of myopathy, hypotonia and controls selected randomly from the population were evaluated for triplet repeat expansion of (CTG)n repeats in the 3’untranslated region (UTR) of DMPK gene, the causative mutation in myotonic dystrophy (DM). DNA was isolated from peripheral blood of 40 individuals; they presented symptoms of muscle myopathy (n = 11), muscle hypotonia (n = 4), members of their families (n = 5) and control individuals from random population (n = 20). Molecular analysis of genomic DNA by polymerase chain reaction (PCR) using primers specific for the DMPK gene encompassing the triplet repeat expansion, showed that all controls (n = 20) gave a 2.1 kb band indicating normal triplet repeat number. Three out of 11 cases (two clinically diagnosed DM and one muscular dystrophy) had an expansion of the (CTG)n repeat in the range of 1000-2100 repeats corresponding to the repeat number in cases of severe DM. Other two of these 11 cases, showed a mild expansion of ~ 66 repeats. Three samples, which included two cases of hypotonia and the father of a subject with muscular dystrophy, also gave a similar repeat expansion (~66 repeats). Conclusion: Results suggest a role of (CTG)n expansion at the DMPK locus in unexplained hypotonias and muscular myopathies other than DM. This calls for screening of the triplet repeat expansion at the DMPK locus in cases of idiopathic myopathies and hypotonia.
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Affiliation(s)
- Vasavi Mohan
- Department of Genetics and Molecular Medicine, Kamineni Hospitals, Lakdikapul, Hyderabad, Andhra Pradesh, India ; Department of Genetics, Vasavi Medical Research Centre, Lakdikapul, Hyderabad, Andhra Pradesh, India
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Völker J, Plum G, Klump HH, Breslauer KJ. Energetic coupling between clustered lesions modulated by intervening triplet repeat bulge loops: allosteric implications for DNA repair and triplet repeat expansion. Biopolymers 2010; 93:355-69. [PMID: 19890964 PMCID: PMC3902826 DOI: 10.1002/bip.21343] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Clusters of closely spaced oxidative DNA lesions present challenges to the cellular repair machinery. When located in opposing strands, base excision repair (BER) of such lesions can lead to double strand DNA breaks (DSB). Activation of BER and DSB repair pathways has been implicated in inducing enhanced expansion of triplet repeat sequences. We show here that energy coupling between distal lesions (8oxodG and/or abasic sites) in opposing DNA strands can be modulated by a triplet repeat bulge loop located between the lesion sites. We find this modulation to be dependent on the identity of the lesions (8oxodG vs. abasic site) and the positions of the lesions (upstream vs. downstream) relative to the intervening bulge loop domain. We discuss how such bulge loop-mediated lesion crosstalk might influence repair processes, while favoring DNA expansion, the genotype of triplet repeat diseases.
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Affiliation(s)
- Jens Völker
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
| | - G.Eric Plum
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
- IBET Inc, 1507 Chambers Road, Suite 301, Columbus, OH 43212
| | - Horst H. Klump
- Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch 7800, South Africa
| | - Kenneth J. Breslauer
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Rd, Piscataway, NJ 08854
- The Cancer Institute of New Jersey, New Brunswick, NJ 08901
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Burnett R, Melander C, Puckett JW, Son LS, Wells RD, Dervan PB, Gottesfeld JM. DNA sequence-specific polyamides alleviate transcription inhibition associated with long GAA.TTC repeats in Friedreich's ataxia. Proc Natl Acad Sci U S A 2006; 103:11497-502. [PMID: 16857735 PMCID: PMC1544198 DOI: 10.1073/pnas.0604939103] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The DNA abnormality found in 98% of Friedreich's ataxia (FRDA) patients is the unstable hyperexpansion of a GAA.TTC triplet repeat in the first intron of the frataxin gene. Expanded GAA.TTC repeats result in decreased transcription and reduced levels of frataxin protein in affected individuals. Beta-alanine-linked pyrrole-imidazole polyamides bind GAA.TTC tracts with high affinity and disrupt the intramolecular DNA.DNA-associated region of the sticky-DNA conformation formed by long GAA.TTC repeats. Fluorescent polyamide-Bodipy conjugates localize in the nucleus of a lymphoid cell line derived from a FRDA patient. The synthetic ligands increase transcription of the frataxin gene in cell culture, resulting in increased levels of frataxin protein. DNA microarray analyses indicate that a limited number of genes are significantly affected in FRDA cells. Polyamides may increase transcription by altering the DNA conformation of genes harboring long GAA.TTC repeats or by chromatin opening.
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Affiliation(s)
- Ryan Burnett
- *Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - Christian Melander
- *Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
| | - James W. Puckett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; and
| | - Leslie S. Son
- Center for Genome Research, Institute for Biosciences and Technology, Texas A&M University System Health Science Center, 2121 West Holcombe Boulevard, Houston, TX 77030
| | - Robert D. Wells
- Center for Genome Research, Institute for Biosciences and Technology, Texas A&M University System Health Science Center, 2121 West Holcombe Boulevard, Houston, TX 77030
| | - Peter B. Dervan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125; and
| | - Joel M. Gottesfeld
- *Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
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