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Mirceta M, Shum N, Schmidt MHM, Pearson CE. Fragile sites, chromosomal lesions, tandem repeats, and disease. Front Genet 2022; 13:985975. [PMID: 36468036 PMCID: PMC9714581 DOI: 10.3389/fgene.2022.985975] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/02/2022] [Indexed: 09/16/2023] Open
Abstract
Expanded tandem repeat DNAs are associated with various unusual chromosomal lesions, despiralizations, multi-branched inter-chromosomal associations, and fragile sites. Fragile sites cytogenetically manifest as localized gaps or discontinuities in chromosome structure and are an important genetic, biological, and health-related phenomena. Common fragile sites (∼230), present in most individuals, are induced by aphidicolin and can be associated with cancer; of the 27 molecularly-mapped common sites, none are associated with a particular DNA sequence motif. Rare fragile sites ( ≳ 40 known), ≤ 5% of the population (may be as few as a single individual), can be associated with neurodevelopmental disease. All 10 molecularly-mapped folate-sensitive fragile sites, the largest category of rare fragile sites, are caused by gene-specific CGG/CCG tandem repeat expansions that are aberrantly CpG methylated and include FRAXA, FRAXE, FRAXF, FRA2A, FRA7A, FRA10A, FRA11A, FRA11B, FRA12A, and FRA16A. The minisatellite-associated rare fragile sites, FRA10B, FRA16B, can be induced by AT-rich DNA-ligands or nucleotide analogs. Despiralized lesions and multi-branched inter-chromosomal associations at the heterochromatic satellite repeats of chromosomes 1, 9, 16 are inducible by de-methylating agents like 5-azadeoxycytidine and can spontaneously arise in patients with ICF syndrome (Immunodeficiency Centromeric instability and Facial anomalies) with mutations in genes regulating DNA methylation. ICF individuals have hypomethylated satellites I-III, alpha-satellites, and subtelomeric repeats. Ribosomal repeats and subtelomeric D4Z4 megasatellites/macrosatellites, are associated with chromosome location, fragility, and disease. Telomere repeats can also assume fragile sites. Dietary deficiencies of folate or vitamin B12, or drug insults are associated with megaloblastic and/or pernicious anemia, that display chromosomes with fragile sites. The recent discovery of many new tandem repeat expansion loci, with varied repeat motifs, where motif lengths can range from mono-nucleotides to megabase units, could be the molecular cause of new fragile sites, or other chromosomal lesions. This review focuses on repeat-associated fragility, covering their induction, cytogenetics, epigenetics, cell type specificity, genetic instability (repeat instability, micronuclei, deletions/rearrangements, and sister chromatid exchange), unusual heritability, disease association, and penetrance. Understanding tandem repeat-associated chromosomal fragile sites provides insight to chromosome structure, genome packaging, genetic instability, and disease.
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Affiliation(s)
- Mila Mirceta
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Natalie Shum
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Monika H. M. Schmidt
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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Katayama KI, Morimura N, Kobayashi K, Corbett D, Okamoto T, Ornthanalai VG, Matsunaga H, Fujita W, Matsumoto Y, Akagi T, Hashikawa T, Yamada K, Murphy NP, Nagao S, Aruga J. Slitrk2 deficiency causes hyperactivity with altered vestibular function and serotonergic dysregulation. iScience 2022; 25:104604. [PMID: 35789858 PMCID: PMC9250022 DOI: 10.1016/j.isci.2022.104604] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 04/14/2022] [Accepted: 06/08/2022] [Indexed: 11/16/2022] Open
Abstract
SLITRK2 encodes a transmembrane protein that modulates neurite outgrowth and synaptic activities and is implicated in bipolar disorder. Here, we addressed its physiological roles in mice. In the brain, the Slitrk2 protein was strongly detected in the hippocampus, vestibulocerebellum, and precerebellar nuclei—the vestibular-cerebellar-brainstem neural network including pontine gray and tegmental reticular nucleus. Slitrk2 knockout (KO) mice exhibited increased locomotor activity in novel environments, antidepressant-like behaviors, enhanced vestibular function, and increased plasticity at mossy fiber–CA3 synapses with reduced sensitivity to serotonin. A serotonin metabolite was increased in the hippocampus and amygdala, and serotonergic neurons in the raphe nuclei were decreased in Slitrk2 KO mice. When KO mice were treated with methylphenidate, lithium, or fluoxetine, the mood stabilizer lithium showed a genotype-dependent effect. Taken together, Slitrk2 deficiency causes aberrant neural network activity, synaptic integrity, vestibular function, and serotonergic function, providing molecular-neurophysiological insight into the brain dysregulation in bipolar disorders. Slitrk2 KO mice showed antidepressant-like behaviors and enhanced vestibular function Mossy fiber-CA3 synaptic sensitivity to serotonin was reduced in Slitrk2 KO mice Serotonin metabolite was increased in hippocampus and amygdala of Slitrk2 KO mice Numbers of serotonergic neurons in raphe nuclei were decreased in Slitrk2 KO mice
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Salesse C, Charest J, Doucet-Beaupré H, Castonguay AM, Labrecque S, De Koninck P, Lévesque M. Opposite Control of Excitatory and Inhibitory Synapse Formation by Slitrk2 and Slitrk5 on Dopamine Neurons Modulates Hyperactivity Behavior. Cell Rep 2021; 30:2374-2386.e5. [PMID: 32075770 DOI: 10.1016/j.celrep.2020.01.084] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 12/03/2019] [Accepted: 01/24/2020] [Indexed: 11/26/2022] Open
Abstract
The neurodevelopmental origin of hyperactivity disorder has been suggested to involve the dopaminergic system, but the underlying mechanisms are still unknown. Here, transcription factors Lmx1a and Lmx1b are shown to be essential for midbrain dopaminergic (mDA) neuron excitatory synaptic inputs and dendritic development. Strikingly, conditional knockout (cKO) of Lmx1a/b in postmitotic mDA neurons results in marked hyperactivity. In seeking Lmx1a/b target genes, we identify positively regulated Slitrk2 and negatively regulated Slitrk5. These two synaptic adhesion proteins promote excitatory and inhibitory synapses on mDA neurons, respectively. Knocking down Slitrk2 reproduces some of the Lmx1a/b cKO cellular and behavioral phenotypes, whereas Slitrk5 knockdown has opposite effects. The hyperactivity caused by this imbalance in excitatory/inhibitory synaptic inputs on dopamine neurons is reproduced by chronically inhibiting the ventral tegmental area during development using pharmacogenetics. Our study shows that alterations in developing dopaminergic circuits strongly impact locomotor activity, shedding light on mechanisms causing hyperactivity behaviors.
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Affiliation(s)
- Charleen Salesse
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | - Julien Charest
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | | | | | - Simon Labrecque
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada
| | - Paul De Koninck
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada; Department of Biochemistry, Microbiology and Bioinformatics, Faculty of Science and Engineering, Université Laval, Québec, QC G1V 0A6, Canada
| | - Martin Lévesque
- CERVO Brain Research Centre, 2601 de la Canardière, Québec, QC G1J 2G3, Canada; Department of Psychiatry and Neuroscience, Faculty of Medicine, Université Laval, Québec, QC G1V 0A6, Canada.
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Watanabe N, Kitada K, Santostefano KE, Yokoyama A, Waldrop SM, Heldermon CD, Tachibana D, Koyama M, Meacham AM, Pacak CA, Terada N. Generation of Induced Pluripotent Stem Cells from a Female Patient with a Xq27.3-q28 Deletion to Establish Disease Models and Identify Therapies. Cell Reprogram 2020; 22:179-188. [PMID: 32608992 DOI: 10.1089/cell.2020.0012] [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] [Indexed: 12/21/2022] Open
Abstract
Since it is extremely difficult to establish an animal model for human chromosomal abnormalities, induced pluripotent stem cells (iPSCs) provide a powerful alternative to study underlying mechanisms of these disorders and identify potential therapeutic interventions. In this study we established iPSCs from a young girl with a hemizygous deletion of Xq27.3-q28 who exhibited global developmental delay and intellectual disability from early in infancy. The deletion site on the X chromosome includes Fragile X Mental Retardation 1 (FMR1), the gene responsible for fragile X syndrome, which likely contributes to the patient's neurodevelopmental abnormalities. The FMR1 gene was expressed in approximately half of the iPSC clones we generated while it was absent in the other half due to the random inactivation of normal and abnormal X chromosomes. The normal or absent expression pattern of the FMR1 gene was not altered when the iPSCs were differentiated into neural progenitor cells (NPCs). Moreover, chromosome reactivating reagents such as 5-aza-2-deoxycytidine, trichostatin A, and UNC0638, were tested in an attempt to reactivate the suppressed FMR1 gene in affected iPSC-NPCs. The affected and control isogenic iPSCs developed in this study are ideal models with which to identify downstream consequences caused by the Xq27.3-q28 deletion and also to provide tools for high-throughput screening to identify compounds potentially improving the well-being of this patient population.
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Affiliation(s)
- Noriko Watanabe
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Kohei Kitada
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | | | - Airi Yokoyama
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Sara M Waldrop
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Coy D Heldermon
- Department of Medicine, and University of Florida College of Medicine, Gainesville, Florida, USA
| | - Daisuke Tachibana
- Depertment of Obstetrics and Gynecology, Osaka City University, Graduate School of Medicine, Osaka, Japan
| | - Masayasu Koyama
- Depertment of Obstetrics and Gynecology, Osaka City University, Graduate School of Medicine, Osaka, Japan
| | - Amy M Meacham
- Department of Medicine, and University of Florida College of Medicine, Gainesville, Florida, USA
| | - Christina A Pacak
- Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida, USA
| | - Naohiro Terada
- Department of Pathology, University of Florida College of Medicine, Gainesville, Florida, USA
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Prontera P, Ottaviani V, Rogaia D, Isidori I, Mencarelli A, Malerba N, Cocciadiferro D, Rolph P, Stangoni G, Vulto-van Silfhout A, Merla G. A novel MED12 mutation: Evidence for a fourth phenotype. Am J Med Genet A 2016; 170:2377-82. [PMID: 27312080 DOI: 10.1002/ajmg.a.37805] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 05/30/2016] [Indexed: 11/11/2022]
Abstract
Mutations of the MED12 gene have been reported mainly in males with FG (Opitz-Kaveggia), Lujan-Fryns, or X-linked Ohdo syndromes. Recently, a different phenotype characterized by minor anomalies, severe intellectual disability (ID), and absent language was reported in female and male patients belonging to the same family and carrying a frameshift MED12 mutation (c.5898dupC). Here, we report on two brothers and their niece affected by severe and mild ID, respectively, where whole exome sequencing combined with variant analysis within a panel of ID-related genes, disclosed a novel c.2312T>C (p.Ile771Thr) MED12 mutation. This variant, which has not been reported as a polymorphism, was not present in a third unaffected brother, and was predicted to be deleterious by five bioinformatic databases. This finding together with the phenotypic analogies shared with the carriers of c.5898dupC mutation suggests the existence of a fourth MED12-related disorder, characterized by severe ID, absent or deficient language and, milder, clinical manifestation in heterozygotes. We have reviewed the literature on MED12 heterozygotes, their clinical manifestations, and discuss the possible biological causes of this condition. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Paolo Prontera
- Medical Genetics Unit, Hospital "Santa Maria della Misericordia", Perugia, Italy
| | - Valentina Ottaviani
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Daniela Rogaia
- Medical Genetics Unit, Hospital "Santa Maria della Misericordia", Perugia, Italy
| | - Ilenia Isidori
- Medical Genetics Unit, Hospital "Santa Maria della Misericordia", Perugia, Italy
| | - Amedea Mencarelli
- Medical Genetics Unit, Hospital "Santa Maria della Misericordia", Perugia, Italy
| | - Natascia Malerba
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - Dario Cocciadiferro
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy.,Ph.D. Program in Experimental and Regenerative Medicine, University of Foggia, Foggia, Italy
| | - Pfundt Rolph
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Gabriela Stangoni
- Medical Genetics Unit, Hospital "Santa Maria della Misericordia", Perugia, Italy
| | - Anneke Vulto-van Silfhout
- Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Giuseppe Merla
- Medical Genetics Unit, IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, Foggia, Italy
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Gatta V, Gennaro E, Franchi S, Cecconi M, Antonucci I, Tommasi M, Palka G, Coviello D, Stuppia L, Grasso M. MS-MLPA analysis for FMR1 gene: evaluation in a routine diagnostic setting. BMC MEDICAL GENETICS 2013; 14:79. [PMID: 23914933 PMCID: PMC3751107 DOI: 10.1186/1471-2350-14-79] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 07/23/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND Fragile X Syndrome (FXS), the most common cause of familiar mental retardation, is associated in over 99% of cases to an expansion over 200 repeats of a CGG sequence in the 5' UTR of the FMR1 gene (Xq27.3), leading to the hypermethylation of the promoter. Molecular diagnosis of FXS have been so far based on the use of the Southern Blot (SB) analysis, a low throughput and time consuming technique. In order to update the diagnostic approach for FXS, we evaluated the usefulness of the Methylation-Specific Multiplex-Ligation-dependent Probe Amplification assay (MS-MLPA). METHODS The study was carried out by retrospectively analysing 44 male patients, 10 Chorionic Villus Sampling (CVS) samples and 10 females previously analyzed by SB. In addition, a prospective study on 98 male subjects, 20 females and 1 CVS sample was carried out for assessing the feasibility and the impact of MS-MLPA in a routine lab work. RESULT Results provided by both the retrospective and the prospective parts of this study strongly demonstrate the robustness and reproducibility of the MS-MLPA assay, able to correctly detect the methylation status in all normal and full mutation male samples analyzed, including CVS male samples. On the other hand, MS-MLPA analysis on females samples produced unreliable results. CONCLUSION Based on our results, we suggest the necessity of a separate workflow for male and female patients with suspected FXS in the routine diagnostic setting. MS-MLPA, in combination with CGG repeat sizing using a single-tube primed FMR1 PCR, represents a reliable diagnostic protocol in the molecular diagnosis of FXS male patients.
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Affiliation(s)
- Valentina Gatta
- Laboratory of Molecular Genetics, Department of Psychological, Humanities and Territorial Sciences, School of Medicine and Health Sciences, G, d'Annunzio University, via dei Vestini 31, Chieti, 66013, Italy.
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Mondal K, Ramachandran D, Patel VC, Hagen KR, Bose P, Cutler DJ, Zwick ME. Excess variants in AFF2 detected by massively parallel sequencing of males with autism spectrum disorder. Hum Mol Genet 2012; 21:4356-64. [PMID: 22773736 DOI: 10.1093/hmg/dds267] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Autism spectrum disorder (ASD) is a heterogeneous disorder with substantial heritability, most of which is unexplained. ASD has a population prevalence of one percent and affects four times as many males as females. Patients with fragile X E (FRAXE) intellectual disability, which is caused by a silencing of the X-linked gene AFF2, display a number of ASD-like phenotypes. Duplications and deletions at the AFF2 locus have also been reported in cases with moderate intellectual disability and ASD. We hypothesized that other rare X-linked sequence variants at the AFF2 locus might contribute to ASD. We sequenced the AFF2 genomic region in 202 male ASD probands and found that 2.5% of males sequenced had missense mutations at highly conserved evolutionary sites. When compared with the frequency of missense mutations in 5545 X chromosomes from unaffected controls, we saw a statistically significant enrichment in patients with ASD (OR: 4.9; P < 0.014). In addition, we identified rare AFF2 3' UTR variants at conserved sites which alter gene expression in a luciferase assay. These data suggest that rare variation in AFF2 may be a previously unrecognized ASD susceptibility locus and may help explain some of the male excess of ASD.
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Affiliation(s)
- Kajari Mondal
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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Stettner GM, Shoukier M, Höger C, Brockmann K, Auber B. Familial intellectual disability and autistic behavior caused by a small FMR2 gene deletion. Am J Med Genet A 2011; 155A:2003-7. [DOI: 10.1002/ajmg.a.34122] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 04/30/2011] [Indexed: 11/06/2022]
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