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Zhang Y, Liu X, Li Z, Li H, Miao Z, Wan B, Xu X. Advances on the Mechanisms and Therapeutic Strategies in Non-coding CGG Repeat Expansion Diseases. Mol Neurobiol 2024:10.1007/s12035-024-04239-9. [PMID: 38780719 DOI: 10.1007/s12035-024-04239-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 05/02/2024] [Indexed: 05/25/2024]
Abstract
Non-coding CGG repeat expansions within the 5' untranslated region are implicated in a range of neurological disorders, including fragile X-associated tremor/ataxia syndrome, oculopharyngeal myopathy with leukodystrophy, and oculopharyngodistal myopathy. This review outlined the general characteristics of diseases associated with non-coding CGG repeat expansions, detailing their clinical manifestations and neuroimaging patterns, which often overlap and indicate shared pathophysiological traits. We summarized the underlying molecular mechanisms of these disorders, providing new insights into the roles that DNA, RNA, and toxic proteins play. Understanding these mechanisms is crucial for the development of targeted therapeutic strategies. These strategies include a range of approaches, such as antisense oligonucleotides, RNA interference, genomic DNA editing, small molecule interventions, and other treatments aimed at correcting the dysregulated processes inherent in these disorders. A deeper understanding of the shared mechanisms among non-coding CGG repeat expansion disorders may hold the potential to catalyze the development of innovative therapies, ultimately offering relief to individuals grappling with these debilitating neurological conditions.
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Affiliation(s)
- Yutong Zhang
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Xuan Liu
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Zeheng Li
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
| | - Hao Li
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China
- Department of Neurology, The Fourth Affiliated Hospital of Soochow University, Suzhou, 215124, China
| | - Zhigang Miao
- The Institute of Neuroscience, Soochow University, Suzhou City, China
| | - Bo Wan
- The Institute of Neuroscience, Soochow University, Suzhou City, China
| | - Xingshun Xu
- Departments of Neurology, The First Affiliated Hospital of Soochow University, Suzhou City, China.
- The Institute of Neuroscience, Soochow University, Suzhou City, China.
- Department of Neurology, The First Affiliated Hospital of Soochow University, Suzhou, 215000, China.
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2
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Datta S, Patel M, Sathyaseelan C, Ghosh C, Mudgal A, Patel D, Rathinavelan T, Singh U. G-quadruplex landscape and its regulation revealed by a new antibody capture method. Oncotarget 2024; 15:175-198. [PMID: 38484151 PMCID: PMC10939474 DOI: 10.18632/oncotarget.28564] [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: 10/27/2023] [Accepted: 02/12/2024] [Indexed: 03/17/2024] Open
Abstract
Our understanding of DNA G-quadruplexes (G4s) from in vitro studies has been complemented by genome-wide G4 landscapes from cultured cells. Conventionally, the formation of G4s is accepted to depend on G-repeats such that they form tetrads. However, genome-wide G4s characterized through high-throughput sequencing suggest that these structures form at a large number of regions with no such canonical G4-forming signatures. Many G4-binding proteins have been described with no evidence for any protein that binds to and stabilizes G4s. It remains unknown what fraction of G4s formed in human cells are protein-bound. The G4-chromatin immunoprecipitation (G4-ChIP) method hitherto employed to describe G4 landscapes preferentially reports G4s that get crosslinked to proteins in their proximity. Our current understanding of the G4 landscape is biased against representation of G4s which escape crosslinking as they are not stabilized by protein-binding and presumably transient. We report a protocol that captures G4s from the cells efficiently without any bias as well as eliminates the detection of G4s formed artifactually on crosslinked sheared chromatin post-fixation. We discover that G4s form sparingly at SINEs. An application of this method shows that depletion of a repeat-binding protein CGGBP1 enhances net G4 capture at CGGBP1-dependent CTCF-binding sites and regions of sharp interstrand G/C-skew transitions. Thus, we present an improved method for G4 landscape determination and by applying it we show that sequence property-specific constraints of the nuclear environment mitigate G4 formation.
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Affiliation(s)
- Subhamoy Datta
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Manthan Patel
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK
| | - Chakkarai Sathyaseelan
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi Campus, Telangana 502285, India
| | - Chandrama Ghosh
- Azrieli Faculty of Medicine, Bar-Ilan University, Henrietta Szold 8A, Safed 1311502, Israel
| | - Akanksha Mudgal
- Department of Biopharmacy, Medical University of Lublin, Lublin 20059, Poland
| | - Divyesh Patel
- Research Programs Unit, Applied Tumor Genomics Program, Faculty of Medicine, University of Helsinki, Biomedicum, Helsinki 00290, Finland
| | | | - Umashankar Singh
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
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Sathyaseelan C, Veerapathiran S, Das U, Ravichandran G, Ajjugal Y, Singh J, Rengan AK, Rathinavelan T, Prabusankar G. Destabilizing Effect of Organo Ru(II) Salts on the Intermolecular Parallel CGG Repeat DNA Quadruplex Associated with Neurodegenerative/Neuromuscular Diseases. ACS Chem Neurosci 2023; 14:3646-3654. [PMID: 37698929 DOI: 10.1021/acschemneuro.3c00285] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023] Open
Abstract
The cationic organo ruthenium(II) salts ([Ru(p-cymene)(ipit)(Cl)](Cl) (RuS), 1-isopropyl-3-(pyridin-2-yl)-imidazol-2-thione (ipit) and [Ru(p-cymene)(ipis)(Cl)](Cl) (RuSe), 1-isopropyl-3-(pyridin-2-yl)-imidazol-2-selenone (ipis)) are isolated, and their binding efficacy with d(CGG)15 quadruplex is investigated. Circular dichroism (CD) wavelength scan titration experiments of RuS and RuSe compounds with the intermolecular parallel quadruplex formed by d(CGG)15 (associated with neurodegenerative/neuromuscular/neuronal intranuclear inclusion disorders like FXTAS, OPMD, OPDM types 1-4, and OPML as well as FXPOI) and with the control d(CGG)15·d(CCG)15 duplex indicate their specificity toward the former. Electrophoretic mobility shift titration experiments also confirm the binding of the ligands with d(CGG)15. CD thermal denaturation experiments indicate that both RuS and RuSe destabilize the quadruplex, specifically at 10 mM concentration of the ligands. This is further confirmed by 1D 1H NMR experiments. Such a destabilizing effect of these ligands on the d(CGG)15 quadruplex indicates that RuS and RuSe chalcogen complexes can act as a template for the design of novel molecules for the diagnostics and/or therapeutics of CGG repeat expansion-associated diseases.
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Affiliation(s)
- Chakkarai Sathyaseelan
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Sabari Veerapathiran
- Organometallics and Materials Chemistry Lab, Department of Chemistry, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Uttam Das
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Gayathri Ravichandran
- Biomedical Engineering, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Yogeeshwar Ajjugal
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Joginder Singh
- Organometallics and Materials Chemistry Lab, Department of Chemistry, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | - Aravind Kumar Rengan
- Biomedical Engineering, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
| | | | - Ganesan Prabusankar
- Organometallics and Materials Chemistry Lab, Department of Chemistry, Indian Institute of Technology Hyderabad, Hyderabad 502284, India
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Ma Y, Budde MW, Zhu J, Elowitz MB. Tuning Methylation-Dependent Silencing Dynamics by Synthetic Modulation of CpG Density. ACS Synth Biol 2023; 12:2536-2545. [PMID: 37572041 PMCID: PMC10510725 DOI: 10.1021/acssynbio.3c00078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Indexed: 08/14/2023]
Abstract
Methylation of cytosines in CG dinucleotides (CpGs) within promoters has been shown to lead to gene silencing in mammals in natural contexts. Recently, engineered recruitment of methyltransferases (DNMTs) at specific loci was shown to be sufficient to silence synthetic and endogenous gene expression through this mechanism. A critical parameter for DNA methylation-based silencing is the distribution of CpGs within the target promoter. However, how the number or density of CpGs in the target promoter affects the dynamics of silencing by DNMT recruitment has remained unclear. Here, we constructed a library of promoters with systematically varying CpG content, and analyzed the rate of silencing in response to recruitment of DNMT. We observed a tight correlation between silencing rate and CpG content. Further, methylation-specific analysis revealed a constant accumulation rate of methylation at the promoter after DNMT recruitment. We identified a single CpG site between TATA box and transcription start site (TSS) that accounted for a substantial part of the difference in silencing rates between promoters with differing CpG content, indicating that certain residues play disproportionate roles in controlling silencing. Together, these results provide a library of promoters for synthetic epigenetic and gene regulation applications, as well as insights into the regulatory link between CpG content and silencing rate.
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Affiliation(s)
- Yitong Ma
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91125, United States
| | - Mark W. Budde
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91125, United States
- Primordium
Labs, Arcadia, California 91006, United States
| | - Junqin Zhu
- Department
of Biology, Stanford University, Stanford, California 94305, United States
| | - Michael B. Elowitz
- Division
of Biology and Biological Engineering, California
Institute of Technology, Pasadena, California 91125, United States
- Howard
Hughes Medical Institute, California Institute
of Technology, Pasadena, California 91125, United States
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Ma Y, Budde MW, Zhu J, Elowitz MB. Tuning methylation-dependent silencing dynamics by synthetic modulation of CpG density. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.30.542205. [PMID: 37398290 PMCID: PMC10312471 DOI: 10.1101/2023.05.30.542205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Methylation of cytosines in CG dinucleotides (CpGs) within promoters has been shown to lead to gene silencing in mammals in natural contexts. Recently, engineered recruitment of methyltransferases (DNMTs) at specific loci was shown to be sufficient to silence synthetic and endogenous gene expression through this mechanism. A critical parameter for DNA methylation-based silencing is the distribution of CpGs within the target promoter. However, how the number or density of CpGs in the target promoter affects the dynamics of silencing by DNMT recruitment has remained unclear. Here we constructed a library of promoters with systematically varying CpG content, and analyzed the rate of silencing in response to recruitment of DNMT. We observed a tight correlation between silencing rate and CpG content. Further, methylation-specific analysis revealed a constant accumulation rate of methylation at the promoter after DNMT recruitment. We identified a single CpG site between TATA box and transcription start site (TSS) that accounted for a substantial part of the difference in silencing rates between promoters with differing CpG content, indicating that certain residues play disproportionate roles in controlling silencing. Together, these results provide a library of promoters for synthetic epigenetic and gene regulation applications, as well as insights into the regulatory link between CpG content and silencing rate.
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Affiliation(s)
- Yitong Ma
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125, USA
| | - Mark W. Budde
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125, USA
- Primordium Labs, Arcadia, CA 91006, USA
| | - Junqin Zhu
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Michael B. Elowitz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA91125, USA
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA
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Ciobanu CG, Nucă I, Popescu R, Antoci LM, Caba L, Ivanov AV, Cojocaru KA, Rusu C, Mihai CT, Pânzaru MC. Narrative Review: Update on the Molecular Diagnosis of Fragile X Syndrome. Int J Mol Sci 2023; 24:9206. [PMID: 37298158 PMCID: PMC10252420 DOI: 10.3390/ijms24119206] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/30/2023] [Accepted: 05/20/2023] [Indexed: 06/12/2023] Open
Abstract
The diagnosis and management of fragile X syndrome (FXS) have significantly improved in the last three decades, although the current diagnostic techniques are not yet able to precisely identify the number of repeats, methylation status, level of mosaicism, and/or the presence of AGG interruptions. A high number of repeats (>200) in the fragile X messenger ribonucleoprotein 1 gene (FMR1) results in hypermethylation of promoter and gene silencing. The actual molecular diagnosis is performed using a Southern blot, TP-PCR (Triplet-Repeat PCR), MS-PCR (Methylation-Specific PCR), and MS-MLPA (Methylation-Specific MLPA) with some limitations, with multiple assays being necessary to completely characterise a patient with FXS. The actual gold standard diagnosis uses Southern blot; however, it cannot accurately characterise all cases. Optical genome mapping is a new technology that has also been developed to approach the diagnosis of fragile X syndrome. Long-range sequencing represented by PacBio and Oxford Nanopore has the potential to replace the actual diagnosis and offers a complete characterization of molecular profiles in a single test. The new technologies have improved the diagnosis of fragile X syndrome and revealed unknown aberrations, but they are a long way from being used routinely in clinical practice.
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Affiliation(s)
- Cristian-Gabriel Ciobanu
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
| | - Irina Nucă
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
- Investigatii Medicale Praxis, St. Moara de Vant No 35, 700376 Iasi, Romania
| | - Roxana Popescu
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
- Medical Genetics Department, “Saint Mary” Emergency Children’s Hospital, St. Vasile Lupu No 62, 700309 Iasi, Romania
| | - Lucian-Mihai Antoci
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
| | - Lavinia Caba
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
| | - Anca Viorica Ivanov
- Pediatrics Department, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania
| | - Karina-Alexandra Cojocaru
- Department of Biochemistry, Faculty of Dental Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania
| | - Cristina Rusu
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
- Medical Genetics Department, “Saint Mary” Emergency Children’s Hospital, St. Vasile Lupu No 62, 700309 Iasi, Romania
| | | | - Monica-Cristina Pânzaru
- Medical Genetics Department, Faculty of Medicine, “Grigore T. Popa” University of Medicine and Pharmacy, University Street No 16, 700115 Iasi, Romania; (C.-G.C.)
- Medical Genetics Department, “Saint Mary” Emergency Children’s Hospital, St. Vasile Lupu No 62, 700309 Iasi, Romania
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Wang G, Vasquez KM. Dynamic alternative DNA structures in biology and disease. Nat Rev Genet 2023; 24:211-234. [PMID: 36316397 DOI: 10.1038/s41576-022-00539-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 55.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Abstract
Repetitive elements in the human genome, once considered 'junk DNA', are now known to adopt more than a dozen alternative (that is, non-B) DNA structures, such as self-annealed hairpins, left-handed Z-DNA, three-stranded triplexes (H-DNA) or four-stranded guanine quadruplex structures (G4 DNA). These dynamic conformations can act as functional genomic elements involved in DNA replication and transcription, chromatin organization and genome stability. In addition, recent studies have revealed a role for these alternative structures in triggering error-generating DNA repair processes, thereby actively enabling genome plasticity. As a driving force for genetic variation, non-B DNA structures thus contribute to both disease aetiology and evolution.
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Affiliation(s)
- Guliang Wang
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA
| | - Karen M Vasquez
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Paediatric Research Institute, Austin, TX, USA.
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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] [Key Words] [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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Affiliation(s)
| | | | - Abrar Qurashi
- Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, India
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Bhanjadeo MM, Nial PS, Sathyaseelan C, Singh AK, Dutta J, Rathinavelan T, Subudhi U. Biophysical interaction between lanthanum chloride and (CG) n or (GC) n repeats: A reversible B-to-Z DNA transition. Int J Biol Macromol 2022; 216:698-709. [PMID: 35809677 DOI: 10.1016/j.ijbiomac.2022.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/30/2022] [Accepted: 07/03/2022] [Indexed: 11/24/2022]
Abstract
The transition from right-handed to left-handed DNA is not only acts as the controlling factor for switching gene expression but also has equal importance in designing nanomechanical devices. The (CG)n and (GC)n repeat sequences are well known model molecules to study B-Z transition in the presence of higher concentration of monovalent cations. In this communication, we report a cyclic transition in (CG)6 DNA using millimolar concentration of trivalent lanthanide salt LaCl3. The controlled and reversible transition was seen in (CG)12, and (GC)12 DNA employing CD spectroscopy. While LaCl3 failed to induce B-Z transition in shorter oligonucleotides such as (CG)3 and (GC)3, a smooth B-Z transition was recorded for (CG)6, (CG)12 and (GC)12 sequences. Interestingly, the phenomenon was reversible (Z-B transition) with addition of EDTA. Particularly, two rounds of cyclic transition (B-Z-B-Z-B) have been noticed in (CG)6 DNA in presence of LaCl3 and EDTA which strongly suggest that B-Z transition is reversible in short repeat sequences. Thermal melting and annealing behaviour of B-DNA are reversible while the thermal melting of LaCl3-induced Z-DNA is irreversible which suggest a stronger binding of LaCl3 to the phosphate backbone of Z-DNA. This was further supported by isothermal titration calorimetric study. Molecular dynamics (MD) simulation indicates that the mode of binding of La3+ (of LaCl3) with d(CG)8.d(CG)8 is through the minor groove, wherein, 3 out of 11 La3+ bridge the anionic oxygens of the complementary strands. Such a tight coordination of La3+ with the anionic oxygens at the minor groove surface may be the reason for the experimentally observed irreversibility of LaCl3-induced Z-DNA seen in longer DNA fragments. Thus, these results indicate LaCl3 can easily be adopted as an inducer of left-handed DNA in other short oligonucleotides sequences to facilitate the understanding of the molecular mechanism of B-Z transition.
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Affiliation(s)
- Madhabi M Bhanjadeo
- DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751 013, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Partha S Nial
- DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751 013, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India
| | - Chakkarai Sathyaseelan
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi Campus, Telangana 502285, India
| | - Ajit K Singh
- Structural Biology Laboratory, DBT-Institute of Life Sciences, Bhubaneswar 751023, India; Department of Pharmacology, University of Vermont College of Medicine, Burlington 05405, USA
| | - Juhi Dutta
- School of Chemical Sciences, National Institute of Science Education & Research, Bhubaneswar 752050, India; Homi Bhaba National Institute, Mumbai 400094, India
| | | | - Umakanta Subudhi
- DNA Nanotechnology & Application Laboratory, CSIR-Institute of Minerals & Materials Technology, Bhubaneswar 751 013, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India.
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Tabolacci E, Nobile V, Pucci C, Chiurazzi P. Mechanisms of the FMR1 Repeat Instability: How Does the CGG Sequence Expand? Int J Mol Sci 2022; 23:ijms23105425. [PMID: 35628235 PMCID: PMC9141726 DOI: 10.3390/ijms23105425] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 05/10/2022] [Accepted: 05/11/2022] [Indexed: 11/16/2022] Open
Abstract
A dynamic mutation in exon 1 of the FMR1 gene causes Fragile X-related Disorders (FXDs), due to the expansion of an unstable CGG repeat sequence. Based on the CGG sequence size, two types of FMR1 alleles are possible: “premutation” (PM, with 56-200 CGGs) and “full mutation” (FM, with >200 triplets). Premutated females are at risk of transmitting a FM allele that, when methylated, epigenetically silences FMR1 and causes Fragile X syndrome (FXS), a very common form of inherited intellectual disability (ID). Expansions events of the CGG sequence are predominant over contractions and are responsible for meiotic and mitotic instability. The CGG repeat usually includes one or more AGG interspersed triplets that influence allele stability and the risk of transmitting FM to children through maternal meiosis. A unique mechanism responsible for repeat instability has not been identified, but several processes are under investigations using cellular and animal models. The formation of unusual secondary DNA structures at the expanded repeats are likely to occur and contribute to the CGG expansion. This review will focus on the current knowledge about CGG repeat instability addressing the CGG sequence expands.
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Affiliation(s)
- Elisabetta Tabolacci
- Dipartimento Scienze della Vita e Sanità Pubblica, Sezione di Medicina Genomica, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy; (E.T.); (V.N.); (C.P.)
| | - Veronica Nobile
- Dipartimento Scienze della Vita e Sanità Pubblica, Sezione di Medicina Genomica, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy; (E.T.); (V.N.); (C.P.)
| | - Cecilia Pucci
- Dipartimento Scienze della Vita e Sanità Pubblica, Sezione di Medicina Genomica, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy; (E.T.); (V.N.); (C.P.)
| | - Pietro Chiurazzi
- Dipartimento Scienze della Vita e Sanità Pubblica, Sezione di Medicina Genomica, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy; (E.T.); (V.N.); (C.P.)
- UOC Genetica Medica, Fondazione Policlinico Universitario “A. Gemelli” IRCCS, 00168 Rome, Italy
- Correspondence: ; Tel.: +39-06-3015-4606
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Bioinformatics Analysis of the Interaction of miRNAs and piRNAs with Human mRNA Genes Having di- and Trinucleotide Repeats. Genes (Basel) 2022; 13:genes13050800. [PMID: 35627185 PMCID: PMC9141802 DOI: 10.3390/genes13050800] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 02/04/2023] Open
Abstract
The variability of nucleotide repeats is considered one of the causes of diseases, but their biological function is not understood. In recent years, the interaction of miRNAs and piRNAs with the mRNAs of genes responsible for developing neurodegenerative and oncological diseases and diabetes have been actively studied. We explored candidate genes with nucleotide repeats to predict associations with miRNAs and piRNAs. The parameters of miRNAs and piRNA binding sites with mRNAs of human genes having nucleotide repeats were determined using the MirTarget program. This program defines the start of the initiation of miRNA and piRNA binding to mRNAs, the localization of miRNA and piRNA binding sites in the 5′-untranslated region (5′UTR), coding sequence (CDS) and 3′-untranslated region (3′UTR); the free energy of binding; and the schemes of nucleotide interactions of miRNAs and piRNAs with mRNAs. The characteristics of miRNAs and piRNA binding sites with mRNAs of 73 human genes were determined. The 5′UTR, 3′UTR and CDS of the mRNAs of genes are involved in the development of neurodegenerative, oncological and diabetes diseases with GU, AC dinucleotide and CCG, CAG, GCC, CGG, CGC trinucleotide repeats. The associations of miRNAs, piRNAs and candidate target genes could be recommended for developing methods for diagnosing diseases, including neurodegenerative diseases, oncological diseases and diabetes.
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Neurodegenerative diseases associated with non-coding CGG tandem repeat expansions. Nat Rev Neurol 2022; 18:145-157. [PMID: 35022573 DOI: 10.1038/s41582-021-00612-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 02/07/2023]
Abstract
Non-coding CGG repeat expansions cause multiple neurodegenerative disorders, including fragile X-associated tremor/ataxia syndrome, neuronal intranuclear inclusion disease, oculopharyngeal myopathy with leukodystrophy, and oculopharyngodistal myopathy. The underlying genetic causes of several of these diseases have been identified only in the past 2-3 years. These expansion disorders have substantial overlapping clinical, neuroimaging and histopathological features. The shared features suggest common mechanisms that could have implications for the development of therapies for this group of diseases - similar therapeutic strategies or drugs may be effective for various neurodegenerative disorders induced by non-coding CGG expansions. In this Review, we provide an overview of clinical and pathological features of these CGG repeat expansion diseases and consider the likely pathological mechanisms, including RNA toxicity, CGG repeat-associated non-AUG-initiated translation, protein aggregation and mitochondrial impairment. We then discuss future research needed to improve the identification and diagnosis of CGG repeat expansion diseases, to improve modelling of these diseases and to understand their pathogenesis. We also consider possible therapeutic strategies. Finally, we propose that CGG repeat expansion diseases may represent manifestations of a single underlying neuromyodegenerative syndrome in which different organs are affected to different extents depending on the gene location of the repeat expansion.
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Natural selection at the RASGEF1C (GGC) repeat in human and divergent genotypes in late-onset neurocognitive disorder. Sci Rep 2021; 11:19235. [PMID: 34584172 PMCID: PMC8479062 DOI: 10.1038/s41598-021-98725-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Accepted: 09/14/2021] [Indexed: 12/17/2022] Open
Abstract
Expression dysregulation of the neuron-specific gene, RASGEF1C (RasGEF Domain Family Member 1C), occurs in late-onset neurocognitive disorders (NCDs), such as Alzheimer's disease. This gene contains a (GGC)13, spanning its core promoter and 5' untranslated region (RASGEF1C-201 ENST00000361132.9). Here we sequenced the (GGC)-repeat in a sample of human subjects (N = 269), consisting of late-onset NCDs (N = 115) and controls (N = 154). We also studied the status of this STR across various primate and non-primate species based on Ensembl 103. The 6-repeat allele was the predominant allele in the controls (frequency = 0.85) and NCD patients (frequency = 0.78). The NCD genotype compartment consisted of an excess of genotypes that lacked the 6-repeat (divergent genotypes) (Mid-P exact = 0.004). A number of those genotypes were not detected in the control group (Mid-P exact = 0.007). The RASGEF1C (GGC)-repeat expanded beyond 2-repeats specifically in primates, and was at maximum length in human. We conclude that there is natural selection for the 6-repeat allele of the RASGEF1C (GGC)-repeat in human, and significant divergence from that allele in late-onset NCDs. STR alleles that are predominantly abundant and genotypes that deviate from those alleles are underappreciated features, which may have deep evolutionary and pathological consequences.
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Ajjugal Y, Rathinavelan T. Conformational distortions induced by periodically recurring A…A in d(CAG).d(CAG) provide stereochemical rationale for the trapping of MSH2.MSH3 in polyQ disorders. Comput Struct Biotechnol J 2021; 19:4447-4455. [PMID: 34471491 PMCID: PMC8379282 DOI: 10.1016/j.csbj.2021.07.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/16/2021] [Accepted: 07/21/2021] [Indexed: 11/25/2022] Open
Abstract
CAG repeat instability causes a number of neurodegenerative disorders. The unusual hairpin stem structure formed by the CAG repeats in DNA traps the human mismatch repair MSH2.MSH3 (Mutsβ) complex. To understand the mechanism behind the abnormal binding of Mutsβ with the imperfect hairpin stem structure formed by CAG repeats, molecular dynamics simulations have been carried out for Mutsβ-d(CAG)2(CAG)(CAG)2.d(CTG)2(CAG)(CTG)2 (1 A…A mismatch) and Mutsβ-d(CAG)5.d(CAG)5 (5 mismatches, wherein, A…A occurs periodically) complexes. The interaction of MSH3 residue Tyr245 at the minor groove side of A…A, an essential interaction responsible for the recognition by Mutsβ, are retained in both the cases. Nevertheless, the periodic unwinding caused by the nonisostericity of A…A with the flanking canonical base pairs in d(CAG)5.d(CAG)5 distorts the regular B-form geometry. Such an unwinding exposes one of the A…A mismatches (that interacts with Tyr245) at the major groove side and also facilitates the on and off hydrogen bonding interaction with Lys546 sidechain (MSH2-domain-IV). In contrast, kinking of the DNA towards the major groove in Mutsβ-d(CAG)2(CAG)(CAG)2.d(CTG)2(CAG)(CTG)2 doesn’t facilitate such an exposure of the bases at the major groove. Further, the unwinding of the helix in d(CAG)5.d(CAG)5 enhances the tighter binding between MSH2-domain-I and d(CAG)5.d(CAG)5 at the major groove side as well as between MSH3-domain-I and MSH3-domain-IV. Markedly, such enhanced interactions are absent in Mutsβ-d(CAG)2(CAG)(CAG)2.d(CTG)2(CAG)(CTG)2 that has a single A…A mismatch. Thus, the above-mentioned enhancement in intra- and inter- molecular interactions in Mutsβ-d(CAG)5.d(CAG)5 provide the stereochemical rationale for the trapping of Mutsβ in CAG repeat expansion disorders.
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Affiliation(s)
- Yogeeshwar Ajjugal
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana State 502285, India
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