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Bijlani S, Pang KM, Bugga LV, Rangasamy S, Narayanan V, Chatterjee S. Nuclease-free precise genome editing corrects MECP2 mutations associated with Rett syndrome. Front Genome Ed 2024; 6:1346781. [PMID: 38495533 PMCID: PMC10940404 DOI: 10.3389/fgeed.2024.1346781] [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] [Received: 11/29/2023] [Accepted: 02/12/2024] [Indexed: 03/19/2024] Open
Abstract
Rett syndrome is an acquired progressive neurodevelopmental disorder caused by de novo mutations in the X-linked MECP2 gene which encodes a pleiotropic protein that functions as a global transcriptional regulator and a chromatin modifier. Rett syndrome predominantly affects heterozygous females while affected male hemizygotes rarely survive. Gene therapy of Rett syndrome has proven challenging due to a requirement for stringent regulation of expression with either over- or under-expression being toxic. Ectopic expression of MECP2 in conjunction with regulatory miRNA target sequences has achieved some success, but the durability of this approach remains unknown. Here we evaluated a nuclease-free homologous recombination (HR)-based genome editing strategy to correct mutations in the MECP2 gene. The stem cell-derived AAVHSCs have previously been shown to mediate seamless and precise HR-based genome editing. We tested the ability of HR-based genome editing to correct pathogenic mutations in Exons 3 and 4 of the MECP2 gene and restore the wild type sequence while preserving all native genomic regulatory elements associated with MECP2 expression, thus potentially addressing a significant issue in gene therapy for Rett syndrome. Moreover, since the mutations are edited directly at the level of the genome, the corrections are expected to be durable with progeny cells inheriting the edited gene. The AAVHSC MECP2 editing vector was designed to be fully homologous to the target MECP2 region and to insert a promoterless Venus reporter at the end of Exon 4. Evaluation of AAVHSC editing in a panel of Rett cell lines bearing mutations in Exons 3 and 4 demonstrated successful correction and rescue of expression of the edited MECP2 gene. Sequence analysis of edited Rett cells revealed successful and accurate correction of mutations in both Exons 3 and 4 and permitted mapping of HR crossover events. Successful correction was observed only when the mutations were flanked at both the 5' and 3' ends by crossover events, but not when both crossovers occurred either exclusively upstream or downstream of the mutation. Importantly, we concluded that pathogenic mutations were successfully corrected in every Rett line analyzed, demonstrating the therapeutic potential of HR-based genome editing.
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Affiliation(s)
- Swati Bijlani
- Department of Surgery, Beckman Research Institute of the City of Hope, Duarte, CA, United States
| | - Ka Ming Pang
- Department of Surgery, Beckman Research Institute of the City of Hope, Duarte, CA, United States
| | - Lakshmi V. Bugga
- Department of Surgery, Beckman Research Institute of the City of Hope, Duarte, CA, United States
| | - Sampath Rangasamy
- Center for Rare Childhood Disorders (C4RCD), Neurogenomics Division, Translational Genomics Research Institute (TGen), Phoenix, AZ, United States
| | - Vinodh Narayanan
- Center for Rare Childhood Disorders (C4RCD), Neurogenomics Division, Translational Genomics Research Institute (TGen), Phoenix, AZ, United States
| | - Saswati Chatterjee
- Department of Surgery, Beckman Research Institute of the City of Hope, Duarte, CA, United States
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Pramanik S, Bala A, Pradhan A. Zebrafish in understanding molecular pathophysiology, disease modeling, and developing effective treatments for Rett syndrome. J Gene Med 2024; 26:e3677. [PMID: 38380785 DOI: 10.1002/jgm.3677] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/04/2024] [Accepted: 01/28/2024] [Indexed: 02/22/2024] Open
Abstract
Rett syndrome (RTT) is a rare but dreadful X-linked genetic disease that mainly affects young girls. It is a neurological disease that affects nerve cell development and function, resulting in severe motor and intellectual disabilities. To date, no cure is available for treating this disease. In 90% of the cases, RTT is caused by a mutation in methyl-CpG-binding protein 2 (MECP2), a transcription factor involved in the repression and activation of transcription. MECP2 is known to regulate several target genes and is involved in different physiological functions. Mouse models exhibit a broad range of phenotypes in recapitulating human RTT symptoms; however, understanding the disease mechanisms remains incomplete, and many potential RTT treatments developed in mouse models have not shown translational effectiveness in human trials. Recent data hint that the zebrafish model emulates similar disrupted neurological functions following mutation of the mecp2 gene. This suggests that zebrafish can be used to understand the onset and progression of RTT pathophysiology and develop a possible cure. In this review, we elaborate on the molecular basis of RTT pathophysiology in humans and model organisms, including rodents and zebrafish, focusing on the zebrafish model to understand the molecular pathophysiology and the development of therapeutic strategies for RTT. Finally, we propose a rational treatment strategy, including antisense oligonucleotides, small interfering RNA technology and induced pluripotent stem cell-derived cell therapy.
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Affiliation(s)
- Subrata Pramanik
- Jyoti and Bhupat Mehta School of Health Sciences and Technology, Indian Institute of Technology Guwahati, Guwahati, Assam, India
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Asis Bala
- Pharmacology and Drug Discovery Research Laboratory, Division of Life Sciences; Institute of Advanced Study in Science and Technology (IASST), An Autonomous Institute Under - Department of Science & Technology (Govt. of India) Vigyan Path, Guwahati, Assam, India
| | - Ajay Pradhan
- Biology, The Life Science Center, School of Science and Technology, Örebro University, Örebro, Sweden
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Fang X, Baggett LM, Caylor RC, Percy AK, Neul JL, Lane JB, Glaze DG, Benke TA, Marsh ED, Motil KJ, Barrish JO, Annese FE, Skinner SA. Parental age effects and Rett syndrome. Am J Med Genet A 2024; 194:160-173. [PMID: 37768187 DOI: 10.1002/ajmg.a.63396] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 08/18/2023] [Indexed: 09/29/2023]
Abstract
Rett syndrome (RTT) is a progressive neurodevelopmental disorder, and pathogenic Methyl-CpG-binding Protein 2 (MECP2) variants are identified in >95% of individuals with typical RTT. Most of RTT-causing variants in MECP2 are de novo and usually on the paternally inherited X chromosome. While paternal age has been reported to be associated with increased risk of genetic disorders, it is unknown whether parental age contributes to the risk of the development of RTT. Clinical data including parental age, RTT diagnostic status, and clinical severity are collected from 1226 participants with RTT and confirmed MECP2 variants. Statistical analyses are performed using Student t-test, single factor analysis of variance (ANOVA), and multi-factor regression. No significant difference is observed in parental ages of RTT probands compared to that of the general population. A small increase in parental ages is observed in participants with missense variants compared to those with nonsense variants. When we evaluate the association between clinical severity and parental ages by multiple regression analysis, there is no clear association between clinical severity and parental ages. Advanced parental ages do not appear to be a risk factor for RTT, and do not contribute to the clinical severity in individuals with RTT.
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Affiliation(s)
- Xiaolan Fang
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | | | | | - Alan K Percy
- The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jeffrey L Neul
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jane B Lane
- The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Tim A Benke
- University of Colorado School of Medicine, Children's Hospital Colorado-Aurora, Denver, Colorado, USA
| | - Eric D Marsh
- Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kathleen J Motil
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | | | - Fran E Annese
- Greenwood Genetic Center, Greenwood, South Carolina, USA
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Siri B, Olivieri G, Lepri FR, Poms M, Goffredo BM, Commone A, Novelli A, Häberle J, Dionisi-Vici C. Father-to-daughter transmission in late-onset OTC deficiency: an underestimated mechanism of inheritance of an X-linked disease. Orphanet J Rare Dis 2024; 19:3. [PMID: 38167094 PMCID: PMC10763478 DOI: 10.1186/s13023-023-02997-8] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Ornithine Transcarbamylase Deficiency (OTCD) is an X-linked urea cycle disorder characterized by acute hyperammonemic episodes. Hemizygous males are usually affected by a severe/fatal neonatal-onset form or, less frequently, by a late-onset form with milder disease course, depending on the residual enzymatic activity. Hyperammonemia can occur any time during life and patients could remain non- or mis-diagnosed due to unspecific symptoms. In heterozygous females, clinical presentation varies based on the extent of X chromosome inactivation. Maternal transmission in X-linked disease is the rule, but in late-onset OTCD, due to the milder phenotype of affected males, paternal transmission to the females is possible. So far, father-to-daughter transmission of OTCD has been reported only in 4 Japanese families. RESULTS We identified in 2 Caucasian families, paternal transmission of late-onset OTCD with severe/fatal outcome in affected males and 1 heterozygous female. Furthermore, we have reassessed the pedigrees of other published reports in 7 additional families with evidence of father-to-daughter inheritance of OTCD, identifying and listing the family members for which this transmission occurred. CONCLUSIONS Our study highlights how the diagnosis and pedigree analysis of late-onset OTCD may represent a real challenge for clinicians. Therefore, the occurrence of paternal transmission in OTCD should not be underestimated, due to the relevant implications for disease inheritance and risk of recurrence.
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Affiliation(s)
- Barbara Siri
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165, Rome, Italy.
- Department of Paediatrics, Città della Salute e della Scienza, OIRM, University of Turin, Turin, Italy.
| | - Giorgia Olivieri
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165, Rome, Italy
| | - Francesca Romana Lepri
- Translational Cytogenomics Research Unit, Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Martin Poms
- Division of Clinical Chemistry and Biochemistry and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Bianca Maria Goffredo
- Division of Metabolism and Metabolic Diseases Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Anna Commone
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165, Rome, Italy
| | - Antonio Novelli
- Translational Cytogenomics Research Unit, Laboratory of Medical Genetics, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Johannes Häberle
- Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Carlo Dionisi-Vici
- Division of Metabolic Diseases and Hepatology, Bambino Gesù Children's Hospital, IRCCS, Piazza S. Onofrio 4, 00165, Rome, Italy
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Canton APM, Tinano FR, Guasti L, Montenegro LR, Ryan F, Shears D, de Melo ME, Gomes LG, Piana MP, Brauner R, Espino-Aguilar R, Escribano-Muñoz A, Paganoni A, Read JE, Korbonits M, Seraphim CE, Costa SS, Krepischi AC, Jorge AAL, David A, Kaisinger LR, Ong KK, Perry JRB, Abreu AP, Kaiser UB, Argente J, Mendonca BB, Brito VN, Howard SR, Latronico AC. Rare variants in the MECP2 gene in girls with central precocious puberty: a translational cohort study. Lancet Diabetes Endocrinol 2023; 11:545-554. [PMID: 37385287 PMCID: PMC7615084 DOI: 10.1016/s2213-8587(23)00131-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 04/22/2023] [Accepted: 04/22/2023] [Indexed: 07/01/2023]
Abstract
BACKGROUND Identification of genetic causes of central precocious puberty have revealed epigenetic mechanisms as regulators of human pubertal timing. MECP2, an X-linked gene, encodes a chromatin-associated protein with a role in gene transcription. MECP2 loss-of-function mutations usually cause Rett syndrome, a severe neurodevelopmental disorder. Early pubertal development has been shown in several patients with Rett syndrome. The aim of this study was to explore whether MECP2 variants are associated with an idiopathic central precocious puberty phenotype. METHODS In this translational cohort study, participants were recruited from seven tertiary centres from five countries (Brazil, Spain, France, the USA, and the UK). Patients with idiopathic central precocious puberty were investigated for rare potentially damaging variants in the MECP2 gene, to assess whether MECP2 might contribute to the cause of central precocious puberty. Inclusion criteria were the development of progressive pubertal signs (Tanner stage 2) before the age of 8 years in girls and 9 years in boys and basal or GnRH-stimulated LH pubertal concentrations. Exclusion criteria were the diagnosis of peripheral precocious puberty and the presence of any recognised cause of central precocious puberty (CNS lesions, known monogenic causes, genetic syndromes, or early exposure to sex steroids). All patients included were followed up at the outpatient clinics of participating academic centres. We used high-throughput sequencing in 133 patients and Sanger sequencing of MECP2 in an additional 271 patients. Hypothalamic expression of Mecp2 and colocalisation with GnRH neurons were determined in mice to show expression of Mecp2 in key nuclei related to pubertal timing regulation. FINDINGS Between Jun 15, 2020, and Jun 15, 2022, 404 patients with idiopathic central precocious puberty (383 [95%] girls and 21 [5%] boys; 261 [65%] sporadic cases and 143 [35%] familial cases from 134 unrelated families) were enrolled and assessed. We identified three rare heterozygous likely damaging coding variants in MECP2 in five girls: a de novo missense variant (Arg97Cys) in two monozygotic twin sisters with central precocious puberty and microcephaly; a de novo missense variant (Ser176Arg) in one girl with sporadic central precocious puberty, obesity, and autism; and an insertion (Ala6_Ala8dup) in two unrelated girls with sporadic central precocious puberty. Additionally, we identified one rare heterozygous 3'UTR MECP2 insertion (36_37insT) in two unrelated girls with sporadic central precocious puberty. None of them manifested Rett syndrome. Mecp2 protein colocalised with GnRH expression in hypothalamic nuclei responsible for GnRH regulation in mice. INTERPRETATION We identified rare MECP2 variants in girls with central precocious puberty, with or without mild neurodevelopmental abnormalities. MECP2 might have a role in the hypothalamic control of human pubertal timing, adding to the evidence of involvement of epigenetic and genetic mechanisms in this crucial biological process. FUNDING Fundação de Amparo à Pesquisa do Estado de São Paulo, Conselho Nacional de Desenvolvimento Científico e Tecnológico, and the Wellcome Trust.
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Affiliation(s)
- Ana P M Canton
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Flávia R Tinano
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Leonardo Guasti
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Luciana R Montenegro
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Fiona Ryan
- Oxford Children's Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Deborah Shears
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | | | - Larissa G Gomes
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Raja Brauner
- Fondation Ophtalmologique Adolphe de Rothschild and Université de Paris, Paris, France
| | | | - Arancha Escribano-Muñoz
- Endocrinology Unit, Department of Pediatrics, Virgen de la Arrixaca University Hospital, Murcia, Spain
| | - Alyssa Paganoni
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Jordan E Read
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Márta Korbonits
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Carlos E Seraphim
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Silvia S Costa
- Discipline of Endocrinology and Metabolism, Clinicas Hospital, School of Medicine and Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Ana Cristina Krepischi
- Discipline of Endocrinology and Metabolism, Clinicas Hospital, School of Medicine and Department of Genetics and Evolutionary Biology, Institute of Biosciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Alexander A L Jorge
- Genetic Endocrinology Unit LIM/25, University of Sao Paulo, Sao Paulo, Brazil
| | - Alessia David
- Centre for Integrative Systems Biology and Bioinformatics, Department of Life Sciences, Imperial College London, London, UK
| | - Lena R Kaisinger
- Medical Research Council Epidemiology Unit, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK
| | - Ken K Ong
- Medical Research Council Epidemiology Unit, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK
| | - John R B Perry
- Medical Research Council Epidemiology Unit, Wellcome-Medical Research Council Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, UK
| | - Ana Paula Abreu
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Ursula B Kaiser
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jesús Argente
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain; Department of Pediatrics and Pediatric Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa, Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, IMDEA Food Institute, Madrid, Spain
| | - Berenice B Mendonca
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Vinicius N Brito
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil
| | - Sasha R Howard
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK; Department of Paediatric Endocrinology, Barts Health NHS Trust, London, UK
| | - Ana Claudia Latronico
- Developmental Endocrinology Unit, Laboratory of Hormones and Molecular Genetics LIM/42, University of Sao Paulo, Sao Paulo, Brazil.
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Wen Y, Wang J, Zhang Q, Yang X, Wei L, Bao X. MECP2 germline mosaicism plays an important part in the inheritance of Rett syndrome: a study of MECP2 germline mosaicism in males. BMC Med 2023; 21:155. [PMID: 37081442 PMCID: PMC10120091 DOI: 10.1186/s12916-023-02846-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 03/23/2023] [Indexed: 04/22/2023] Open
Abstract
BACKGROUND Germline mosaicisms could be inherited to offspring, which considered as "de novo" in most cases. Paternal germline MECP2 mosaicism has been reported in fathers of girls with Rett syndrome (RTT) previously. For further study, we focused on MECP2 germline mosaicism in males, not only RTT fathers. METHODS Thirty-two fathers of RTT girls with MECP2 pathogenic mutations and twenty-five healthy adult males without history and family history of RTT or other genetic disorders were recruited. Sperm samples were collected and ten MECP2 hotspot mutations were detected by micro-droplet digital PCR (mDDPCR). And routine semen test was performed at the same time if the sample was sufficient. Additionally, blood samples were also detected for those with sperm MECP2 mosaicisms. RESULTS Nine fathers with RTT daughters (28.1%, 9/32) were found to have MECP2 mosaicism in their sperm samples, with the mutant allele fractions (MAFs) ranging from 0.05% to 7.55%. Only one father with MECP2 c.806delG germline mosaicism (MAF 7.55%) was found to have mosaicism in the blood sample, with the MAF was 0.28%. In the group of healthy adult males, MECP2 mosaicism was found in 7 sperm samples (28.0%, 7/25), with the MAFs ranging from 0.05% to 0.18%. None of the healthy adult males with MECP2 germline mosaicisms were found with MECP2 mosaicism in blood samples. There were no statistical differences in age, or the incidence of asthenospermia between fathers with RTT daughters and healthy adult males with MECP2 germline mosaicisms. Additionally, there was no linear correlation between MAFs of MECP2 mosaicisms and the age of males with germline MECP2 mosaicisms. CONCLUSIONS Germline MECP2 mosaicism could be found not only in fathers with RTT daughters but also in healthy adult males without family history of RTT. As germline mosaic mutations may be passed on to offspring which commonly known as "de novo", more attention should be paid to germline mosaicism, especially in families with a proband diagnosed with genetic disorders.
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Affiliation(s)
- Yongxin Wen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
- Department of Pediatric Neurology, Guangdong Women and Children Hospital, Guangzhou, Guangdong Province, China
| | - Jiaping Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Qingping Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiaoxu Yang
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Liping Wei
- Center for Bioinformatics, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Xinhua Bao
- Department of Pediatrics, Peking University First Hospital, Beijing, China.
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Shaheen G, Fleischman D. A case of JOAG in a patient with Rett syndrome. Am J Ophthalmol Case Rep 2023; 29:101762. [DOI: 10.1016/j.ajoc.2022.101762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/16/2022] [Accepted: 11/26/2022] [Indexed: 12/05/2022] Open
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Cooley Coleman JA, Fee T, Bend R, Louie R, Annese F, Stallworth J, Worthington J, Buchanan CB, Everman DB, Skinner S, Friez MJ, Jones JR, Spellicy CJ. Mosaicism of common pathogenic MECP2 variants identified in two males with a clinical diagnosis of Rett syndrome. Am J Med Genet A 2022; 188:2988-2998. [PMID: 35924478 DOI: 10.1002/ajmg.a.62913] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [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: 03/22/2022] [Revised: 05/31/2022] [Accepted: 07/07/2022] [Indexed: 01/31/2023]
Abstract
Rett (RTT) syndrome, a neurodevelopmental disorder caused by pathogenic variation in the MECP2 gene, is characterized by developmental regression, loss of purposeful hand movements, stereotypic hand movements, abnormal gait, and loss of spoken language. Due to the X-linked inheritance pattern, RTT is typically limited to females. Recent studies revealed somatic mosaicism in MECP2 in male patients with RTT-like phenotypes. While detecting mosaic variation using Sanger sequencing is theoretically possible for mosaicism over ~15%-20%, several variables, including efficiency of PCR, background noise, and/or human error, contribute to a low detection rate using this technology. Mosaic variants in two males were detected by next generation sequencing (NGS; Case 1) and by Sanger re-sequencing (Case 2). Both had targeted digital PCR (dPCR) to confirm the variants. In this report, we present two males with classic RTT syndrome in whom we identified pathogenic variation in the MECP2 gene in the mosaic state (c.730C > T (p.Gln244*) in Patient 1 and c.397C > T (p.Arg133Cys) in Patient 2). In addition, estimates and measures of mosaic variant fraction were surprisingly similar between Sanger sequencing, NGS, and dPCR. The mosaic state of these variants contributed to a lengthy diagnostic odyssey for these patients. While NGS and even Sanger sequencing may be viable methods of detecting mosaic variation in DNA or RNA samples, applying targeted dPCR to supplement these sequencing technologies would provide confirmation of somatic mosaicism and mosaic fraction.
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Affiliation(s)
| | - Timothy Fee
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Renee Bend
- Greenwood Genetic Center, Greenwood, South Carolina, USA.,PreventionGenetics LLC, Marshfield, Wisconsin, USA
| | - Raymond Louie
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Fran Annese
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Jennifer Stallworth
- Greenwood Genetic Center, Greenwood, South Carolina, USA.,Sanofi, Bridgewater, New Jersey, USA
| | | | | | | | - Steven Skinner
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | | | - Julie R Jones
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Catherine J Spellicy
- Greenwood Genetic Center, Greenwood, South Carolina, USA.,Myriad Genetics, Salt Lake City, Utah, USA
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9
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Coorey B, Haase F, Ellaway C, Clarke A, Lisowski L, Gold WA. Gene Editing and Rett Syndrome: Does It Make the Cut? CRISPR J 2022; 5:490-499. [PMID: 35881862 DOI: 10.1089/crispr.2022.0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurogenetic disorder caused by pathogenic variants of the Methyl CpG binding protein 2 (MECP2) gene. The RTT is characterized by apparent normal early development followed by regression of communicative and fine motor skills. Comorbidities include epilepsy, severe cognitive impairment, and autonomic and motor dysfunction. Despite almost 60 clinical trials and the promise of a gene therapy, no cure has yet emerged with treatment remaining symptomatic. Advances in understanding RTT has provided insight into the complexity and exquisite control of MECP2 expression, where loss of expression leads to RTT and overexpression leads to MECP2 duplication syndrome. Therapy development requires regulated expression that matches the spatiotemporal endogenous expression of MECP2 in the brain. Gene editing has revolutionized gene therapy and promises an exciting strategy for many incurable monogenic disorders, including RTT, by editing the native locus and retaining endogenous gene expression. Here, we review the literature on the currently available editing technologies and discuss their limitations and applicability to the treatment of RTT.
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Affiliation(s)
- Bronte Coorey
- Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia.,Molecular Neurobiology Research Laboratory, Kid's Research, Westmead, Australia.,Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, Australia
| | - Florencia Haase
- Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia.,Molecular Neurobiology Research Laboratory, Kid's Research, Westmead, Australia.,Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, Australia
| | - Carolyn Ellaway
- Genetic Metabolic Disorders Service, Sydney Children's Hospital Network Sydney, Westmead, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Angus Clarke
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Leszek Lisowski
- Translational Vectorology Research Unit, Children's Medical Research Institute, The University of Sydney, Westmead, Australia.,Vector and Genome Engineering Facility, Children's Medical Research Institute, The University of Sydney, Westmead, Australia.,Laboratory of Molecular Oncology and Innovative Therapies, Military Institute of Medicine, Warsaw, Poland
| | - Wendy A Gold
- Faculty of Medicine and Health, School of Medical Sciences, The University of Sydney, Sydney, Australia.,Molecular Neurobiology Research Laboratory, Kid's Research, Westmead, Australia.,Kids Neuroscience Centre, Kids Research, Children's Hospital at Westmead, Westmead, Australia.,Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.,Children's Medical Research Institute, Westmead, Australia
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10
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Jiang CC, Lin LS, Long S, Ke XY, Fukunaga K, Lu YM, Han F. Signalling pathways in autism spectrum disorder: mechanisms and therapeutic implications. Signal Transduct Target Ther 2022; 7:229. [PMID: 35817793 PMCID: PMC9273593 DOI: 10.1038/s41392-022-01081-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 06/19/2022] [Accepted: 06/23/2022] [Indexed: 02/06/2023] Open
Abstract
Autism spectrum disorder (ASD) is a prevalent and complex neurodevelopmental disorder which has strong genetic basis. Despite the rapidly rising incidence of autism, little is known about its aetiology, risk factors, and disease progression. There are currently neither validated biomarkers for diagnostic screening nor specific medication for autism. Over the last two decades, there have been remarkable advances in genetics, with hundreds of genes identified and validated as being associated with a high risk for autism. The convergence of neuroscience methods is becoming more widely recognized for its significance in elucidating the pathological mechanisms of autism. Efforts have been devoted to exploring the behavioural functions, key pathological mechanisms and potential treatments of autism. Here, as we highlight in this review, emerging evidence shows that signal transduction molecular events are involved in pathological processes such as transcription, translation, synaptic transmission, epigenetics and immunoinflammatory responses. This involvement has important implications for the discovery of precise molecular targets for autism. Moreover, we review recent insights into the mechanisms and clinical implications of signal transduction in autism from molecular, cellular, neural circuit, and neurobehavioural aspects. Finally, the challenges and future perspectives are discussed with regard to novel strategies predicated on the biological features of autism.
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Affiliation(s)
- Chen-Chen Jiang
- International Joint Laboratory for Drug Target of Critical Illnesses; Key Laboratory of Cardiovascular & Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China
| | - Li-Shan Lin
- Department of Physiology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, China
| | - Sen Long
- Department of Pharmacy, Hangzhou Seventh People's Hospital, Mental Health Center Zhejiang University School of Medicine, Hangzhou, 310013, China
| | - Xiao-Yan Ke
- Child Mental Health Research Center, Nanjing Brain Hospital, Nanjing Medical University, Nanjing, 210029, China
| | - Kohji Fukunaga
- Department of CNS Drug Innovation, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan
| | - Ying-Mei Lu
- Department of Physiology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, 211166, China.
| | - Feng Han
- International Joint Laboratory for Drug Target of Critical Illnesses; Key Laboratory of Cardiovascular & Cerebrovascular Medicine, School of Pharmacy, Nanjing Medical University, Nanjing, 211166, China. .,Institute of Brain Science, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, 210029, China. .,Gusu School, Nanjing Medical University, Suzhou Municipal Hospital, The Affiliated Suzhou Hospital of Nanjing Medical University, Suzhou, 215002, China.
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11
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Bin Akhtar G, Buist M, Rastegar M. MeCP2 and transcriptional control of eukaryotic gene expression. Eur J Cell Biol 2022. [DOI: 10.1016/j.ejcb.2022.151237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 04/30/2022] [Accepted: 05/09/2022] [Indexed: 11/19/2022] Open
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12
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Steinkellner H, Kempaiah P, Beribisky AV, Pferschy S, Etzler J, Huber A, Sarne V, Neuhaus W, Kuttke M, Bauer J, Arunachalam JP, Christodoulou J, Dressel R, Mildner A, Prinz M, Laccone F. TAT-MeCP2 protein variants rescue disease phenotypes in human and mouse models of Rett syndrome. Int J Biol Macromol 2022; 209:972-983. [PMID: 35460749 DOI: 10.1016/j.ijbiomac.2022.04.080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/08/2022] [Accepted: 04/11/2022] [Indexed: 01/02/2023]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by pathogenic variants leading to functional impairment of the MeCP2 protein. Here, we used purified recombinant MeCP2e1 and MeCP2e2 protein variants fused to a TAT protein transduction domain (PTD) to evaluate their transduction ability into RTT patient-derived fibroblasts and the ability to carry out their cellular function. We then assessed their transduction ability and therapeutic effects in a RTT mouse model. In vitro, TAT-MeCP2e2-eGFP reversed the pathological hyperacetylation of histones H3K9 and H4K16, a hallmark of abolition of MeCP2 function. In vivo, intraperitoneal administration of TAT-MeCP2e1 and TAT-MeCP2e2 extended the lifespan of Mecp2-/y mice by >50%. This was accompanied by rescue of hippocampal CA2 neuron size in animals treated with TAT-MeCP2e1. Taken together, these findings provide a strong indication that recombinant TAT-MeCP2 can reach mouse brains following peripheral injection and can ameliorate the phenotype of RTT mouse models. Thus, our study serves as a first step in the development of a potentially novel RTT therapy.
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Affiliation(s)
- Hannes Steinkellner
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria
| | - Prakasha Kempaiah
- Institute for Human Genetics, Georg August University, Universitätsmedizin Göttingen, 37073 Göttingen, Germany; Division of Infectious Diseases, Mayo Clinic, Jacksonville, FL, USA
| | - Alexander V Beribisky
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria
| | - Sandra Pferschy
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria
| | - Julia Etzler
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria
| | - Anna Huber
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria; Vienna Doctoral School of Pharmaceutical, Nutritional and Sport Sciences (PhaNuSpo), University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Victoria Sarne
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria
| | - Winfried Neuhaus
- AIT Austrian Institute of Technology GmbH, Competence Center Molecular Diagnostics, 1210 Vienna, Austria
| | - Mario Kuttke
- Institute for Vascular Biology, Center for Physiology and Pharmacology, Medical University Vienna, Vienna, Austria
| | - Jan Bauer
- Department of Neuroimmunology, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Jayamuruga P Arunachalam
- Institute for Human Genetics, Georg August University, Universitätsmedizin Göttingen, 37073 Göttingen, Germany; Division of Infectious Diseases, Mayo Clinic, Jacksonville, FL, USA; Department of Medicine, University of Toronto, Medical Sciences Building, 1 King's College Circle, Toronto, ON, Canada
| | - John Christodoulou
- Murdoch Children's Research Institute and Department of Paediatrics, University of Melbourne, Discipline of Child & Adolescent Health, Sydney Medical School, Australia
| | - Ralf Dressel
- Department of Cellular and Molecular Immunology, Georg August University, Universitätsmedizin Göttingen, 37073 Göttingen, Germany
| | - Alexander Mildner
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany; Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Marco Prinz
- Institute of Neuropathology, Medical Faculty, University of Freiburg, Freiburg, Germany; Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
| | - Franco Laccone
- Center for Pathobiochemistry and Genetics, Institute of Medical Genetics, Medical University of Vienna, 1090 Vienna, Austria; Institute for Human Genetics, Georg August University, Universitätsmedizin Göttingen, 37073 Göttingen, Germany; Department of Cellular and Molecular Immunology, Georg August University, Universitätsmedizin Göttingen, 37073 Göttingen, Germany.
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13
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Fang X, Butler KM, Abidi F, Gass J, Beisang A, Feyma T, Ryther RC, Standridge S, Heydemann P, Jones M, Haas R, Lieberman DN, Marsh E, Benke TA, Skinner S, Neul JL, Percy AK, Friez MJ, Caylor RC. Analysis of X-inactivation status in a Rett syndrome natural history study cohort. Mol Genet Genomic Med 2022; 10:e1917. [PMID: 35318820 PMCID: PMC9034674 DOI: 10.1002/mgg3.1917] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/15/2022] [Accepted: 02/17/2022] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Rett syndrome (RTT) is a rare neurodevelopmental disorder associated with pathogenic MECP2 variants. Because the MECP2 gene is subject to X-chromosome inactivation (XCI), factors including MECP2 genotypic variation, tissue differences in XCI, and skewing of XCI all likely contribute to the clinical severity of individuals with RTT. METHODS We analyzed the XCI patterns from blood samples of 320 individuals and their mothers. It includes individuals with RTT (n = 287) and other syndromes sharing overlapping phenotypes with RTT (such as CDKL5 Deficiency Disorder [CDD, n = 16]). XCI status in each proband/mother duo and the parental origin of the preferentially inactivated X chromosome were analyzed. RESULTS The average XCI ratio in probands was slightly increased compared to their unaffected mothers (73% vs. 69%, p = .0006). Among the duos with informative XCI data, the majority of individuals with classic RTT had their paternal allele preferentially inactivated (n = 180/220, 82%). In sharp contrast, individuals with CDD had their maternal allele preferentially inactivated (n = 10/12, 83%). Our data indicate a weak positive correlation between XCI skewing ratio and clinical severity scale (CSS) scores in classic RTT patients with maternal allele preferentially inactivated XCI (rs = 0.35, n = 40), but not in those with paternal allele preferentially inactivated XCI (rs = -0.06, n = 180). The most frequent MECP2 pathogenic variants were enriched in individuals with highly/moderately skewed XCI patterns, suggesting an association with higher levels of XCI skewing. CONCLUSION These results extend our understanding of the pathogenesis of RTT and other syndromes with overlapping clinical features by providing insight into the both XCI and the preferential XCI of parental alleles.
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Affiliation(s)
- Xiaolan Fang
- Greenwood Genetic CenterGreenwoodSouth CarolinaUSA
| | | | - Fatima Abidi
- Greenwood Genetic CenterGreenwoodSouth CarolinaUSA
| | - Jennifer Gass
- Florida Cancer Specialists & Research InstituteFort MyersFLUSA,Present address:
Florida Cancer Specialists & Research InstituteFort MyersFloridaUSA
| | - Arthur Beisang
- Gillette Children’s Specialty HealthcareSt. PaulMinnesotaUSA
| | - Timothy Feyma
- Gillette Children’s Specialty HealthcareSt. PaulMinnesotaUSA
| | - Robin C. Ryther
- Department of NeurologyWashington University School of MedicineSt. LouisMissouriUSA
| | - Shannon Standridge
- Division of NeurologyCincinnati Children’s Hospital Medical CenterCincinnatiOhioUSA,Department of Pediatrics, College of MedicineUniversity of CincinnatiCincinnatiOhioUSA
| | | | - Mary Jones
- Oakland Children’s Hospital, UCSFOaklandCaliforniaUSA
| | - Richard Haas
- University of California San DiegoSan DiegoCaliforniaUSA
| | - David N Lieberman
- Department of NeurologyBoston Children’s HospitalBostonMassachusettsUSA
| | - Eric D. Marsh
- Children’s Hospital of Philadelphia and University of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Tim A. Benke
- University of Colorado School of Medicine, Children’s Hospital Colorado‐AuroraDenverColoradoUSA
| | | | - Jeffrey L. Neul
- Vanderbilt Kennedy CenterVanderbilt University Medical CenterNashville TN
| | - Alan K. Percy
- The University of Alabama at BirminghamBirminghamAlabamaUSA
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14
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Collins BE, Neul JL. Rett Syndrome and MECP2 Duplication Syndrome: Disorders of MeCP2 Dosage. Neuropsychiatr Dis Treat 2022; 18:2813-2835. [PMID: 36471747 PMCID: PMC9719276 DOI: 10.2147/ndt.s371483] [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] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 11/14/2022] [Indexed: 11/30/2022] Open
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused predominantly by loss-of-function mutations in the gene Methyl-CpG-binding protein 2 (MECP2), which encodes the MeCP2 protein. RTT is a MECP2-related disorder, along with MECP2 duplication syndrome (MDS), caused by gain-of-function duplications of MECP2. Nearly two decades of research have advanced our knowledge of MeCP2 function in health and disease. The following review will discuss MeCP2 protein function and its dysregulation in the MECP2-related disorders RTT and MDS. This will include a discussion of the genetic underpinnings of these disorders, specifically how sporadic X-chromosome mutations arise and manifest in specific populations. We will then review current diagnostic guidelines and clinical manifestations of RTT and MDS. Next, we will delve into MeCP2 biology, describing the dual landscapes of methylated DNA and its reader MeCP2 across the neuronal genome as well as the function of MeCP2 as a transcriptional modulator. Following this, we will outline common MECP2 mutations and genotype-phenotype correlations in both diseases, with particular focus on mutations associated with relatively mild disease in RTT. We will also summarize decades of disease modeling and resulting molecular, synaptic, and behavioral phenotypes associated with RTT and MDS. Finally, we list several therapeutics in the development pipeline for RTT and MDS and available evidence of their safety and efficacy.
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Affiliation(s)
- Bridget E Collins
- Medical Scientist Training Program, Vanderbilt University, Nashville, TN, USA
| | - Jeffrey L Neul
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special Education, Vanderbilt University Medical Center and Vanderbilt University, Nashville, TN, USA
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15
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Bouzroud W, Tazzite A, Berrada S, Gazzaz B, Dehbi H. R306X Mutation in the MECP2 Gene Causes an Atypical Rett Syndrome in a Moroccan Patient: A Case Report. Clin Pathol 2022; 15:2632010X221124269. [PMID: 36147795 PMCID: PMC9486266 DOI: 10.1177/2632010x221124269] [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] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022]
Abstract
Rett syndrome (RTT) is a rare X-linked syndrome that predominantly affects girls.
It is characterized by a severe and progressive neurodevelopmental disorder with
neurological regression and autism spectrum features. The Rett syndrome is
associated with a broad phenotypic spectrum. It ranges from a classical Rett
syndrome defined by well-established criteria to atypical cases with symptoms
similar to other syndromes, such as Angelman syndrome. The first case of a
Moroccan female child carrying a R306X mutation in the MECP2
(Methyl-CpG-Binding Protein 2) gene, with an unusual manifestation of Rett
syndrome, is presented here. She showed autistic regression, behavioral
stagnation, epilepsy, unmotivated laughter, and craniofacial dysmorphia. Whole
exome sequencing revealed a nonsense mutation (R306X), resulting in a truncated,
nonfunctional MECP2 protein. The overlapping phenotypic spectrums between Rett
and Angelman syndromes have been described, and an interaction between the
MECP2 gene and the UBE3A (Ubiquitin
Protein Ligase E3A) gene pathways is possible but has not yet been proven. An
extensive genetic analysis is highly recommended in atypical cases to ensure an
accurate diagnosis and to improve patient management and genetic counseling.
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Affiliation(s)
- Wafaa Bouzroud
- Medical Genetics Laboratory, Ibn Rochd University Hospital, Casablanca, Morocco
| | - Amal Tazzite
- Laboratory of Cellular and Molecular Pathology, Faculty of Medicine and Pharmacy, Hassan II University, Casablanca, Morocco
| | - Sarah Berrada
- Medical Genetics Laboratory, Ibn Rochd University Hospital, Casablanca, Morocco
| | - Bouchaïb Gazzaz
- Laboratory of Cellular and Molecular Pathology, Faculty of Medicine and Pharmacy, Hassan II University, Casablanca, Morocco.,Genetics Analysis Institute, Royal Gendarmerie, Rabat, Morocco
| | - Hind Dehbi
- Medical Genetics Laboratory, Ibn Rochd University Hospital, Casablanca, Morocco.,Laboratory of Cellular and Molecular Pathology, Faculty of Medicine and Pharmacy, Hassan II University, Casablanca, Morocco
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16
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Neier K, Grant TE, Palmer RL, Chappell D, Hakam SM, Yasui KM, Rolston M, Settles ML, Hunter SS, Madany A, Ashwood P, Durbin-Johnson B, LaSalle JM, Yasui DH. Sex disparate gut microbiome and metabolome perturbations precede disease progression in a mouse model of Rett syndrome. Commun Biol 2021; 4:1408. [PMID: 34916612 PMCID: PMC8677842 DOI: 10.1038/s42003-021-02915-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 05/10/2021] [Accepted: 11/11/2021] [Indexed: 12/24/2022] Open
Abstract
Rett syndrome (RTT) is a regressive neurodevelopmental disorder in girls, characterized by multisystem complications including gut dysbiosis and altered metabolism. While RTT is known to be caused by mutations in the X-linked gene MECP2, the intermediate molecular pathways of progressive disease phenotypes are unknown. Mecp2 deficient rodents used to model RTT pathophysiology in most prior studies have been male. Thus, we utilized a patient-relevant mouse model of RTT to longitudinally profile the gut microbiome and metabolome across disease progression in both sexes. Fecal metabolites were altered in Mecp2e1 mutant females before onset of neuromotor phenotypes and correlated with lipid deficiencies in brain, results not observed in males. Females also displayed altered gut microbial communities and an inflammatory profile that were more consistent with RTT patients than males. These findings identify new molecular pathways of RTT disease progression and demonstrate the relevance of further study in female Mecp2 animal models.
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Affiliation(s)
- Kari Neier
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Tianna E Grant
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Rebecca L Palmer
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Demario Chappell
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Sophia M Hakam
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | | | - Matt Rolston
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | | | | | - Abdullah Madany
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Paul Ashwood
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
| | - Blythe Durbin-Johnson
- UC Davis Genome Center, Davis, CA, USA
- UC Davis School of Medicine, Department of Public Health Sciences, Davis, CA, USA
| | - Janine M LaSalle
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA.
- UC Davis Genome Center, Davis, CA, USA.
| | - Dag H Yasui
- UC Davis School of Medicine, Department of Medical Microbiology and Immunology, Genome Center, MIND Institute, Davis, CA, USA
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17
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Zhytnik L, Peters M, Tilk K, Simm K, Tõnisson N, Reimand T, Maasalu K, Acharya G, Krjutškov K, Salumets A. From late fatherhood to prenatal screening of monogenic disorders: evidence and ethical concerns. Hum Reprod Update 2021; 27:1056-1085. [PMID: 34329448 DOI: 10.1093/humupd/dmab023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [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: 03/08/2021] [Revised: 06/27/2021] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND With the help of ART, an advanced parental age is not considered to be a serious obstacle for reproduction anymore. However, significant health risks for future offspring hide behind the success of reproductive medicine for the treatment of reduced fertility associated with late parenthood. Although an advanced maternal age is a well-known risk factor for poor reproductive outcomes, understanding the impact of an advanced paternal age on offspring is yet to be elucidated. De novo monogenic disorders (MDs) are highly associated with late fatherhood. MDs are one of the major sources of paediatric morbidity and mortality, causing significant socioeconomic and psychological burdens to society. Although individually rare, the combined prevalence of these disorders is as high as that of chromosomal aneuploidies, indicating the increasing need for prenatal screening. With the help of advanced reproductive technologies, families with late paternity have the option of non-invasive prenatal testing (NIPT) for multiple MDs (MD-NIPT), which has a sensitivity and specificity of almost 100%. OBJECTIVE AND RATIONALE The main aims of the current review were to examine the effect of late paternity on the origin and nature of MDs, to highlight the role of NIPT for the detection of a variety of paternal age-associated MDs, to describe clinical experiences and to reflect on the ethical concerns surrounding the topic of late paternity and MD-NIPT. SEARCH METHODS An extensive search of peer-reviewed publications (1980-2021) in English from the PubMed and Google Scholar databases was based on key words in different combinations: late paternity, paternal age, spermatogenesis, selfish spermatogonial selection, paternal age effect, de novo mutations (DNMs), MDs, NIPT, ethics of late fatherhood, prenatal testing and paternal rights. OUTCOMES An advanced paternal age provokes the accumulation of DNMs, which arise in continuously dividing germline cells. A subset of DNMs, owing to their effect on the rat sarcoma virus protein-mitogen-activated protein kinase signalling pathway, becomes beneficial for spermatogonia, causing selfish spermatogonial selection and outgrowth, and in some rare cases may lead to spermatocytic seminoma later in life. In the offspring, these selfish DNMs cause paternal age effect (PAE) disorders with a severe and even life-threatening phenotype. The increasing tendency for late paternity and the subsequent high risk of PAE disorders indicate an increased need for a safe and reliable detection procedure, such as MD-NIPT. The MD-NIPT approach has the capacity to provide safe screening for pregnancies at risk of PAE disorders and MDs, which constitute up to 20% of all pregnancies. The primary risks include pregnancies with a paternal age over 40 years, a previous history of an affected pregnancy/child, and/or congenital anomalies detected by routine ultrasonography. The implementation of NIPT-based screening would support the early diagnosis and management needed in cases of affected pregnancy. However, the benefits of MD-NIPT need to be balanced with the ethical challenges associated with the introduction of such an approach into routine clinical practice, namely concerns regarding reproductive autonomy, informed consent, potential disability discrimination, paternal rights and PAE-associated issues, equity and justice in accessing services, and counselling. WIDER IMPLICATIONS Considering the increasing parental age and risks of MDs, combined NIPT for chromosomal aneuploidies and microdeletion syndromes as well as tests for MDs might become a part of routine pregnancy management in the near future. Moreover, the ethical challenges associated with the introduction of MD-NIPT into routine clinical practice need to be carefully evaluated. Furthermore, more focus and attention should be directed towards the ethics of late paternity, paternal rights and paternal genetic guilt associated with pregnancies affected with PAE MDs.
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Affiliation(s)
- Lidiia Zhytnik
- Competence Centre on Health Technologies, Tartu, Estonia
| | - Maire Peters
- Competence Centre on Health Technologies, Tartu, Estonia.,Department of Obstetrics and Gynaecology, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Kadi Tilk
- Competence Centre on Health Technologies, Tartu, Estonia
| | - Kadri Simm
- Institute of Philosophy and Semiotics, Faculty of Arts and Humanities, University of Tartu, Tartu, Estonia.,Centre of Ethics, University of Tartu, Tartu, Estonia
| | - Neeme Tõnisson
- Institute of Genomics, University of Tartu, Tartu, Estonia.,Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia.,Department of Reproductive Medicine, West Tallinn Central Hospital, Tallinn, Estonia
| | - Tiia Reimand
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia.,Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Katre Maasalu
- Clinic of Traumatology and Orthopaedics, Tartu University Hospital, Tartu, Estonia.,Department of Traumatology and Orthopaedics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Ganesh Acharya
- Division of Obstetrics and Gynaecology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
| | - Kaarel Krjutškov
- Competence Centre on Health Technologies, Tartu, Estonia.,Department of Obstetrics and Gynaecology, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
| | - Andres Salumets
- Competence Centre on Health Technologies, Tartu, Estonia.,Department of Obstetrics and Gynaecology, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia.,Institute of Genomics, University of Tartu, Tartu, Estonia.,Division of Obstetrics and Gynaecology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden
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18
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Collins BE, Merritt JK, Erickson KR, Neul JL. Safety and efficacy of genetic MECP2 supplementation in the R294X mouse model of Rett syndrome. Genes Brain Behav 2021; 21:e12739. [PMID: 33942492 PMCID: PMC8563491 DOI: 10.1111/gbb.12739] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 03/30/2021] [Revised: 04/29/2021] [Accepted: 05/01/2021] [Indexed: 01/03/2023]
Abstract
Rett syndrome is a neurodevelopmental disorder caused predominantly by loss-of-function mutations in MECP2, encoding transcriptional modulator methyl-CpG-binding protein 2 (MeCP2). Although no disease-modifying therapies exist at this time, some proposed therapeutic strategies aim to supplement the mutant allele with a wild-type allele producing typical levels of functional MeCP2, such as gene therapy. Because MECP2 is a dosage-sensitive gene, with both loss and gain of function causing disease, these approaches must achieve a narrow therapeutic window to be both safe and effective. While MeCP2 supplementation rescues RTT-like phenotypes in mouse models, the tolerable threshold of MeCP2 is not clear, particularly for partial loss-of-function mutations. We assessed the safety of genetically supplementing full-length human MeCP2 in the context of the R294X allele, a common partial loss-of-function mutation retaining DNA-binding capacity. We assessed the potential for adverse effects from MeCP2 supplementation of a partial loss-of-function mutant and the potential for dominant negative interactions between mutant and full-length MeCP2. In male hemizygous R294X mice, MeCP2 supplementation rescued RTT-like behavioral phenotypes and did not elicit behavioral evidence of excess MeCP2. In female heterozygous R294X mice, RTT-specific phenotypes were similarly rescued. However, MeCP2 supplementation led to evidence of excess MeCP2 activity in a motor coordination assay, suggesting that the underlying motor circuitry is particularly sensitive to MeCP2 dosage in females. These results show that genetic supplementation of full-length MeCP2 is safe in males and largely so females. However, careful consideration of risk for adverse motor effects may be warranted for girls and women with RTT.
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Affiliation(s)
| | - Jonathan K. Merritt
- Department of PediatricsVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Kirsty R. Erickson
- Department of PediatricsVanderbilt University Medical CenterNashvilleTennesseeUSA
| | - Jeffrey L. Neul
- Vanderbilt Kennedy Center, Departments of Pediatrics, Pharmacology, and Special EducationVanderbilt University Medical Center and Vanderbilt UniversityNashvilleTennesseeUSA
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19
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Abstract
MeCP2 protein, encoded by the MECP2 gene, binds to DNA and affects transcription. Outside of this activity the true range of MeCP2 function is still not entirely clear. As MECP2 gene mutations cause the neurodevelopmental disorder Rett syndrome in 1 in 10,000 female births, much of what is known about the biologic function of MeCP2 comes from studying human cell culture models and rodent models with Mecp2 gene mutations. In this review, the full scope of MeCP2 research available in the NIH Pubmed (https://pubmed.ncbi.nlm.nih.gov/) data base to date is considered. While not all original research can be mentioned due to space limitations, the main aspects of MeCP2 and Rett syndrome research are discussed while highlighting the work of individual researchers and research groups. First, the primary functions of MeCP2 relevant to Rett syndrome are summarized and explored. Second, the conflicting evidence and controversies surrounding emerging aspects of MeCP2 biology are examined. Next, the most obvious gaps in MeCP2 research studies are noted. Finally, the most recent discoveries in MeCP2 and Rett syndrome research are explored with a focus on the potential and pitfalls of novel treatments and therapies.
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Affiliation(s)
- Osman Sharifi
- LaSalle Laboratory, Department of Medical Microbiology and Immunology, UC Davis School of Medicine, Davis, CA, United States
| | - Dag H Yasui
- LaSalle Laboratory, Department of Medical Microbiology and Immunology, UC Davis School of Medicine, Davis, CA, United States
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20
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Rizk M, Saker Z, Harati H, Fares Y, Bahmad HF, Nabha S. Deciphering the roles of glycogen synthase kinase 3 (GSK3) in the treatment of autism spectrum disorder and related syndromes. Mol Biol Rep 2021; 48:2669-2686. [PMID: 33650079 DOI: 10.1007/s11033-021-06237-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 02/12/2021] [Indexed: 02/08/2023]
Abstract
Autism spectrum disorder (ASD) is a complex and multifactorial neurodevelopmental disorder characterized by the presence of restricted interests and repetitive behaviors besides deficits in social communication. Syndromic ASD is a subset of ASD caused by underlying genetic disorders, most commonly Fragile X Syndrome (FXS) and Rett Syndrome (RTT). Various mutations and consequent malfunctions in core signaling pathways have been identified in ASD, including glycogen synthase kinase 3 (GSK3). A growing body of evidence suggests a key role of GSK3 dysregulation in the pathogenesis of ASD and its related disorders. Here, we provide a synopsis of the implication of GSK3 in ASD, FXS, and RTT as a promising therapeutic target for the treatment of ASD.
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Affiliation(s)
- Mahdi Rizk
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Zahraa Saker
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Hayat Harati
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Youssef Fares
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon.,Department of Neurosurgery, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon
| | - Hisham F Bahmad
- Arkadi M. Rywlin M.D. Department of Pathology and Laboratory Medicine, Mount Sinai Medical Center, 4300 Alton Rd, Miami Beach, FL, 33140, USA
| | - Sanaa Nabha
- Neuroscience Research Center, Faculty of Medical Sciences, Lebanese University, Beirut, Lebanon.
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21
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Castells AA, Balada R, Tristán-Noguero A, O'Callaghan M, Cortès-Saladelafont E, Pascual-Alonso A, Garcia-Cazorla À, Armstrong J, Alcántara S. Unraveling Molecular Pathways Altered in MeCP2-Related Syndromes, in the Search for New Potential Avenues for Therapy. Biomedicines 2021; 9:148. [PMID: 33546327 DOI: 10.3390/biomedicines9020148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/25/2021] [Accepted: 01/30/2021] [Indexed: 12/27/2022] Open
Abstract
Methyl-CpG-binding protein 2 (MeCP2) is an X-linked epigenetic modulator whose dosage is critical for neural development and function. Loss-of-function mutations in MECP2 cause Rett Syndrome (RTT, OMIM #312750) while duplications in the Xq28 locus containing MECP2 and Interleukin-1 receptor-associated kinase 1 (IRAK1) cause MECP2 duplication syndrome (MDS, OMIM #300260). Both are rare neurodevelopmental disorders that share clinical symptoms, including intellectual disability, loss of speech, hand stereotypies, vasomotor deficits and seizures. The main objective of this exploratory study is to identify novel signaling pathways and potential quantitative biomarkers that could aid early diagnosis and/or the monitoring of disease progression in clinical trials. We analyzed by RT-PCR gene expression in whole blood and microRNA (miRNA) expression in plasma, in a cohort of 20 females with Rett syndrome, 2 males with MECP2 duplication syndrome and 28 healthy controls, and correlated RNA expression with disease and clinical parameters. We have identified a set of potential biomarker panels for RTT diagnostic and disease stratification of patients with microcephaly and vasomotor deficits. Our study sets the basis for larger studies leading to the identification of specific miRNA signatures for early RTT detection, stratification, disease progression and segregation from other neurodevelopmental disorders. Nevertheless, these data will require verification and validation in further studies with larger sample size including a whole range of ages.
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22
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Bressan P, Kramer P. Mental Health, Mitochondria, and the Battle of the Sexes. Biomedicines 2021; 9:biomedicines9020116. [PMID: 33530498 PMCID: PMC7911591 DOI: 10.3390/biomedicines9020116] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 01/12/2023] Open
Abstract
This paper presents a broad perspective on how mental disease relates to the different evolutionary strategies of men and women and to growth, metabolism, and mitochondria—the enslaved bacteria in our cells that enable it all. Several mental disorders strike one sex more than the other; yet what truly matters, regardless of one’s sex, is how much one’s brain is “female” and how much it is “male”. This appears to be the result of an arms race between the parents over how many resources their child ought to extract from the mother, hence whether it should grow a lot or stay small and undemanding. An uneven battle alters the child’s risk of developing not only insulin resistance, diabetes, or cancer, but a mental disease as well. Maternal supremacy increases the odds of a psychosis-spectrum disorder; paternal supremacy, those of an autism-spectrum one. And a particularly lopsided struggle may invite one or the other of a series of syndromes that come in pairs, with diametrically opposite, excessively “male” or “female” characteristics. By providing the means for this tug of war, mitochondria take center stage in steadying or upsetting the precarious balance on which our mental health is built.
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Abstract
Mutations in methyl CpG binding protein 2 (MeCP2) are the major cause of Rett syndrome (RTT), a rare neurodevelopmental disorder with a notable period of developmental regression following apparently normal initial development. Such MeCP2 alterations often result in changes to DNA binding and chromatin clustering ability, and in the stability of this protein. Among other functions, MeCP2 binds to methylated genomic DNA, which represents an important epigenetic mark with broad physiological implications, including neuronal development. In this review, we will summarize the genetic foundations behind RTT, and the variable degrees of protein stability exhibited by MeCP2 and its mutated versions. Also, past and emerging relationships that MeCP2 has with mRNA splicing, miRNA processing, and other non-coding RNAs (ncRNA) will be explored, and we suggest that these molecules could be missing links in understanding the epigenetic consequences incurred from genetic ablation of this important chromatin modifier. Importantly, although MeCP2 is highly expressed in the brain, where it has been most extensively studied, the role of this protein and its alterations in other tissues cannot be ignored and will also be discussed. Finally, the additional complexity to RTT pathology introduced by structural and functional implications of the two MeCP2 isoforms (MeCP2-E1 and MeCP2-E2) will be described. Epigenetic therapeutics are gaining clinical popularity, yet treatment for Rett syndrome is more complicated than would be anticipated for a purely epigenetic disorder, which should be taken into account in future clinical contexts.
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Affiliation(s)
- Katrina V. Good
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - John B. Vincent
- Molecular Neuropsychiatry & Development (MiND) Lab, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Juan Ausió
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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Meyyazhagan A, Balasubramanian B, Kathannan S, Alagamuthu KK, Easwaran M, Shanmugam S, Pappusamy M, Bhotla HK, Mustaqahamed S, Arumugam VA, Kaul T, Keshavarao S. Scrutinizing the molecular, biochemical, and cytogenetic attributes in subjects with Rett syndrome (RTT) and their mothers. Epilepsy Behav 2020; 111:107277. [PMID: 32653844 DOI: 10.1016/j.yebeh.2020.107277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 11/21/2022]
Abstract
Rett syndrome (RTT) is a stern dominant progressive neurological development disorder linked with X chromosome ranking second for mental slowdown, exclusively in females after few months of birth with normal development and growth period. Genetically any defects in universally expressed methyl-CpG binding protein 2 (MeCP2) transcription regulator gene are considered as radix for RTT in almost all the previous studies. Our study mainly focuses in unraveling the genetic alterations like identifying MeCP2 gene polymorphisms, chromosomal abnormalities, or X-chromosome inactivation (XCI) as underlying cause of RTT in prototypes sorted through Diagnostic and Statistical Manual of Mental Disorders-Text Revised (DSM IV). In addition, we have examined the probable surrogates of brain function disabilities like serotonin, homocysteine (Hcy), calcium, potassium, and lead from blood in both RTT porotypes and their mothers. In our investigation, we have observed varied amino acid substitution of MeCP2 and varied frequency of skewed XCI in RTT prototype. Our study validates that the demonstration of chromosomal analysis, biochemical analysis, and genomic observations helps in concluding RTT condition and can be helpful in providing appropriate treatment and counseling as well as improve the currently available protocol of diagnosis.
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25
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Javed S, Selliah T, Lee YJ, Huang WH. Dosage-sensitive genes in autism spectrum disorders: From neurobiology to therapy. Neurosci Biobehav Rev 2020; 118:538-567. [PMID: 32858083 DOI: 10.1016/j.neubiorev.2020.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 07/26/2020] [Accepted: 08/17/2020] [Indexed: 12/24/2022]
Abstract
Autism spectrum disorders (ASDs) are a group of heterogenous neurodevelopmental disorders affecting 1 in 59 children. Syndromic ASDs are commonly associated with chromosomal rearrangements or dosage imbalance involving a single gene. Many of these genes are dosage-sensitive and regulate transcription, protein homeostasis, and synaptic function in the brain. Despite vastly different molecular perturbations, syndromic ASDs share core symptoms including social dysfunction and repetitive behavior. However, each ASD subtype has a unique pathogenic mechanism and combination of comorbidities that require individual attention. We have learned a great deal about how these dosage-sensitive genes control brain development and behaviors from genetically-engineered mice. Here we describe the clinical features of eight monogenic neurodevelopmental disorders caused by dosage imbalance of four genes, as well as recent advances in using genetic mouse models to understand their pathogenic mechanisms and develop intervention strategies. We propose that applying newly developed quantitative molecular and neuroscience technologies will advance our understanding of the unique neurobiology of each disorder and enable the development of personalized therapy.
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Affiliation(s)
- Sehrish Javed
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
| | - Tharushan Selliah
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
| | - Yu-Ju Lee
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
| | - Wei-Hsiang Huang
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.
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26
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Pejhan S, Del Bigio MR, Rastegar M. The MeCP2E1/E2-BDNF- miR132 Homeostasis Regulatory Network Is Region-Dependent in the Human Brain and Is Impaired in Rett Syndrome Patients. Front Cell Dev Biol 2020; 8:763. [PMID: 32974336 PMCID: PMC7471663 DOI: 10.3389/fcell.2020.00763] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [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: 04/06/2020] [Accepted: 07/21/2020] [Indexed: 11/13/2022] Open
Abstract
Rett Syndrome (RTT) is a rare and progressive neurodevelopmental disorder that is caused by de novo mutations in the X-linked Methyl CpG binding protein 2 (MECP2) gene and is subjected to X-chromosome inactivation. RTT is commonly associated with neurological regression, autistic features, motor control impairment, seizures, loss of speech and purposeful hand movements, mainly affecting females. Different animal and cellular model systems have tremendously contributed to our current knowledge about MeCP2 and RTT. However, the majority of these findings remain unexamined in the brain of RTT patients. Based on previous studies in rodent brains, the highly conserved neuronal microRNA “miR132” was suggested to be an inhibitor of MeCP2 expression. The neuronal miR132 itself is induced by Brain Derived Neurotrophic Factor (BDNF), a neurotransmitter modulator, which in turn is controlled by MeCP2. This makes the basis of the MECP2-BDNF-miR132 feedback regulatory loop in the brain. Here, we studied the components of this feedback regulatory network in humans, and its possible impairment in the brain of RTT patients. In this regard, we evaluated the transcript and protein levels of MECP2/MeCP2E1 and E2 isoforms, BDNF/BDNF, and miR132 (both 3p and 5p strands) by real time RT-PCR, Western blot, and ELISA in four different regions of the human RTT brains and their age-, post-mortem delay-, and sex-matched controls. The transcript level of the studied elements was significantly compromised in RTT patients, even though the change was not identical in different parts of the brain. Our data indicates that MeCP2E1/E2-BDNF protein levels did not follow their corresponding transcript trends. Correlational studies suggested that the MECP2E1/E2-BDNF-miR132 homeostasis regulation might not be similarly controlled in different parts of the human brain. Despite challenges in evaluating autopsy samples in rare diseases, our findings would help to shed some light on RTT pathobiology, and obscurities caused by limited studies on MeCP2 regulation in the human brain.
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Affiliation(s)
- Shervin Pejhan
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Marc R Del Bigio
- Department of Pathology, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
| | - Mojgan Rastegar
- Regenerative Medicine Program, Department of Biochemistry and Medical Genetics, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada
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27
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Varderidou-Minasian S, Hinz L, Hagemans D, Posthuma D, Altelaar M, Heine VM. Quantitative proteomic analysis of Rett iPSC-derived neuronal progenitors. Mol Autism 2020; 11:38. [PMID: 32460858 PMCID: PMC7251722 DOI: 10.1186/s13229-020-00344-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [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: 02/25/2020] [Accepted: 05/04/2020] [Indexed: 12/12/2022] Open
Abstract
Background Rett syndrome (RTT) is a progressive neurodevelopmental disease that is characterized by abnormalities in cognitive, social, and motor skills. RTT is often caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2). The mechanism by which impaired MeCP2 induces the pathological abnormalities in the brain is not understood. Both patients and mouse models have shown abnormalities at molecular and cellular level before typical RTT-associated symptoms appear. This implies that underlying mechanisms are already affected during neurodevelopmental stages. Methods To understand the molecular mechanisms involved in disease onset, we used an RTT patient induced pluripotent stem cell (iPSC)-based model with isogenic controls and performed time-series of proteomic analysis using in-depth high-resolution quantitative mass spectrometry during early stages of neuronal development. Results We provide mass spectrometry-based quantitative proteomic data, depth of about 7000 proteins, at neuronal progenitor developmental stages of RTT patient cells and isogenic controls. Our data gives evidence of proteomic alteration at early neurodevelopmental stages, suggesting alterations long before the phase that symptoms of RTT syndrome become apparent. Significant changes are associated with the GO enrichment analysis in biological processes cell-cell adhesion, actin cytoskeleton organization, neuronal stem cell population maintenance, and pituitary gland development, next to protein changes previously associated with RTT, i.e., dendrite morphology and synaptic deficits. Differential expression increased from early to late neural stem cell phases, although proteins involved in immunity, metabolic processes, and calcium signaling were affected throughout all stages analyzed. Limitations The limitation of our study is the number of RTT patients analyzed. As the aim of our study was to investigate a large number of proteins, only one patient was considered, of which 3 different RTT iPSC clones and 3 isogenic control iPSC clones were included. Even though this approach allowed the study of mutation-induced alterations due to the usage of isogenic controls, results should be validated on different RTT patients to suggest common disease mechanisms. Conclusions During early neuronal differentiation, there are consistent and time-point specific proteomic alterations in RTT patient cells carrying exons 3–4 deletion in MECP2. We found changes in proteins involved in pathway associated with RTT phenotypes, including dendrite morphology and synaptogenesis. Our results provide a valuable resource of proteins and pathways for follow-up studies, investigating common mechanisms involved during early disease stages of RTT syndrome.
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Affiliation(s)
- Suzy Varderidou-Minasian
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584, CH, Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Lisa Hinz
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Dominique Hagemans
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584, CH, Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Danielle Posthuma
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.,Child and Youth Psychiatry, Emma Children's Hospital, Amsterdam UMC, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, 3584, CH, Utrecht, The Netherlands.,Netherlands Proteomics Center, Padualaan 8, 3584, CH, Utrecht, The Netherlands
| | - Vivi M Heine
- Department of Complex Trait Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. .,Child and Youth Psychiatry, Emma Children's Hospital, Amsterdam UMC, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
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28
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Ribeiro MC, MacDonald JL. Sex differences in Mecp2-mutant Rett syndrome model mice and the impact of cellular mosaicism in phenotype development. Brain Res 2020; 1729:146644. [PMID: 31904347 DOI: 10.1016/j.brainres.2019.146644] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [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: 10/03/2019] [Revised: 12/08/2019] [Accepted: 12/31/2019] [Indexed: 12/29/2022]
Abstract
There is currently no effective treatment for Rett syndrome (RTT), a severe X-linked progressive neurodevelopmental disorder caused by mutations in the transcriptional regulator MECP2. Because MECP2 is subjected to X-inactivation, most affected individuals are female heterozygotes who display cellular mosaicism for normal and mutant MECP2. Males who are hemizygous for mutant MECP2 are more severely affected than heterozygous females and rarely survive. Mecp2 loss-of-function is less severe in mice, however, and male hemizygous null mice not only survive until adulthood, they have been the most commonly studied model system. Although heterozygous female mice better recapitulate human RTT, they have not been as thoroughly characterized. This is likely because of the added experimental challenges that they present, including delayed and more variable phenotypic progression and cellular mosaicism due to X-inactivation. In this review, we compare phenotypes of Mecp2 heterozygous female mice and male hemizygous null mouse models. Further, we discuss the complexities that arise from the many cell-type and tissue-type specific roles of MeCP2, as well as the combination of cell-autonomous and non-cell-autonomous disruptions that result from Mecp2 loss-of-function. This is of particular importance in the context of the female heterozygous brain, composed of a mixture of MeCP2+ and MeCP2- cells, the ratio of which can alter RTT phenotypes in the case of skewed X-inactivation. The goal of this review is to provide a clearer understanding of the pathophysiological differences between the mouse models, which is an essential consideration in the design of future pre-clinical studies.
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Affiliation(s)
- Mayara C Ribeiro
- Department of Biology, Program in Neuroscience, Syracuse University, Syracuse, NY, United States
| | - Jessica L MacDonald
- Department of Biology, Program in Neuroscience, Syracuse University, Syracuse, NY, United States.
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29
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Lavery LA, Zoghbi HY. The distinct methylation landscape of maturing neurons and its role in Rett syndrome pathogenesis. Curr Opin Neurobiol 2019; 59:180-188. [PMID: 31542590 PMCID: PMC6892602 DOI: 10.1016/j.conb.2019.08.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/21/2019] [Indexed: 02/06/2023]
Abstract
Rett syndrome (RTT) is one of the most common causes of intellectual and developmental disabilities in girls, and is caused by mutations in the gene encoding methyl-CpG binding protein 2 (MECP2). Here we will review our current understanding of RTT, the landscape of pathogenic mutations and function of MeCP2, and culminate with recent advances elucidating the distinct DNA methylation landscape in the brain that may explain why disease symptoms are delayed and selective to the nervous system.
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Affiliation(s)
- Laura A Lavery
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Huda Y Zoghbi
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA.
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30
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Fahmi M, Yasui G, Seki K, Katayama S, Kaneko-Kawano T, Inazu T, Kubota Y, Ito M. In Silico Study of Rett Syndrome Treatment-Related Genes, MECP2, CDKL5, and FOXG1, by Evolutionary Classification and Disordered Region Assessment. Int J Mol Sci 2019; 20:ijms20225593. [PMID: 31717404 PMCID: PMC6888432 DOI: 10.3390/ijms20225593] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/31/2019] [Accepted: 11/05/2019] [Indexed: 12/28/2022] Open
Abstract
Rett syndrome (RTT), a neurodevelopmental disorder, is mainly caused by mutations in methyl CpG-binding protein 2 (MECP2), which has multiple functions such as binding to methylated DNA or interacting with a transcriptional co-repressor complex. It has been established that alterations in cyclin-dependent kinase-like 5 (CDKL5) or forkhead box protein G1 (FOXG1) correspond to distinct neurodevelopmental disorders, given that a series of studies have indicated that RTT is also caused by alterations in either one of these genes. We investigated the evolution and molecular features of MeCP2, CDKL5, and FOXG1 and their binding partners using phylogenetic profiling to gain a better understanding of their similarities. We also predicted the structural order-disorder propensity and assessed the evolutionary rates per site of MeCP2, CDKL5, and FOXG1 to investigate the relationships between disordered structure and other related properties with RTT. Here, we provide insight to the structural characteristics, evolution and interaction landscapes of those three proteins. We also uncovered the disordered structure properties and evolution of those proteins which may provide valuable information for the development of therapeutic strategies of RTT.
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Affiliation(s)
- Muhamad Fahmi
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (M.F.); (G.Y.); (K.S.)
| | - Gen Yasui
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (M.F.); (G.Y.); (K.S.)
| | - Kaito Seki
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (M.F.); (G.Y.); (K.S.)
| | - Syouichi Katayama
- Department of Pharmacy, College of Pharmaceutical Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (S.K.); (T.K.-K.); (T.I.)
| | - Takako Kaneko-Kawano
- Department of Pharmacy, College of Pharmaceutical Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (S.K.); (T.K.-K.); (T.I.)
| | - Tetsuya Inazu
- Department of Pharmacy, College of Pharmaceutical Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (S.K.); (T.K.-K.); (T.I.)
| | - Yukihiko Kubota
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan;
| | - Masahiro Ito
- Advanced Life Sciences Program, Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan; (M.F.); (G.Y.); (K.S.)
- Department of Bioinformatics, College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan;
- Correspondence:
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Hettiarachchi D, Neththikumara NF, Pathirana BAPS, Dissanayake VHW. Variant Profile of MECP2 Gene in Sri Lankan Patients with Rett Syndrome. J Autism Dev Disord 2019; 50:118-126. [DOI: 10.1007/s10803-019-04230-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Rett syndrome (RTT) is a severe neurological disorder caused by mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). Almost two decades of research into RTT have greatly advanced our understanding of the function and regulation of the multifunctional protein MeCP2. Here, we review recent advances in understanding how loss of MeCP2 impacts different stages of brain development, discuss recent findings demonstrating the molecular role of MeCP2 as a transcriptional repressor, assess primary and secondary effects of MeCP2 loss and examine how loss of MeCP2 can result in an imbalance of neuronal excitation and inhibition at the circuit level along with dysregulation of activity-dependent mechanisms. These factors present challenges to the search for mechanism-based therapeutics for RTT and suggest specific approaches that may be more effective than others.
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Abstract
DNA methylation is a major epigenetic process that regulates chromatin structure which causes transcriptional activation or repression of genes in a context-dependent manner. In general, DNA methylation takes place when methyl groups are added to the appropriate bases on the genome by the action of "writer" molecules known as DNA methyltransferases. How these methylation marks are read and interpreted into different functionalities represents one of the main mechanisms through which the genes are switched "ON" or "OFF" and typically involves different types of "reader" proteins that can recognize and bind to the methylated regions. A tightly balanced regulation exists between the "writers" and "readers" in order to mediate normal cellular functions. However, alterations in normal methylation pattern is a typical hallmark of cancer which alters the way methylation marks are written, read and interpreted in different disease states. This unique characteristic of DNA methylation "readers" has identified them as attractive therapeutic targets. In this review, we describe the current state of knowledge on the different classes of DNA methylation "readers" identified thus far along with their normal biological functions, describe how they are dysregulated in cancer, and discuss the various anti-cancer therapies that are currently being developed and evaluated for targeting these proteins.
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Affiliation(s)
- Niaz Mahmood
- Department of Medicine, McGill University Health Centre, Montréal, QC, Canada
| | - Shafaat A Rabbani
- Department of Medicine, McGill University Health Centre, Montréal, QC, Canada
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Steinkellner H, Schönegger A, Etzler J, Kempaiah P, Huber A, Hahn K, Rose K, Duerr M, Christodoulou J, Beribisky AV, Neuhaus W, Laccone F. An electrochemiluminescence based assay for quantitative detection of endogenous and exogenously applied MeCP2 protein variants. Sci Rep 2019; 9:7929. [PMID: 31138832 DOI: 10.1038/s41598-019-44372-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/15/2019] [Indexed: 11/08/2022] Open
Abstract
Methyl-CpG-binding protein 2 (MeCP2) is a multifunctional chromosomal protein that plays a key role in the central nervous system. Its levels need to be tightly regulated, as both deficiency and excess of the protein can lead to severe neuronal dysfunction. Loss-of-function mutations affecting MeCP2 are the primary cause of Rett syndrome (RTT), a severe neurological disorder that is thought to result from absence of functional protein in the brain. Several therapeutic strategies for the treatment of RTT are currently being developed. One of them is the use of stable and native TAT-MeCP2 fusion proteins to replenish its levels in neurons after permeation across the blood-brain barrier (BBB). Here we describe the expression and purification of various transactivator of transcription (TAT)-MeCP2 variants and the development of an electrochemiluminescence based assay (ECLIA) that is able to measure endogenous MeCP2 and recombinant TAT-MeCP2 fusion protein levels in a 96-well plate format. The MeCP2 ECLIA produces highly quantitative, accurate and reproducible measurements with low intra- and inter-assay error throughout a wide working range. To underline its broad applicability, this assay was used to analyze brain tissue and study the transport of TAT-MeCP2 variants across an in vitro model of the blood-brain barrier.
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Operto FF, Mazza R, Pastorino GMG, Verrotti A, Coppola G. Epilepsy and genetic in Rett syndrome: A review. Brain Behav 2019; 9:e01250. [PMID: 30929312 PMCID: PMC6520293 DOI: 10.1002/brb3.1250] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 02/03/2019] [Accepted: 02/10/2019] [Indexed: 12/14/2022] Open
Abstract
INTRODUCTION Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder that primarily affects girls, with an incidence of 1:10,000-20,000. The diagnosis is based on clinical features: an initial period of apparently normal development (ages 6-12 months) followed by a rapid decline with regression of acquired motor skills, loss of spoken language and purposeful hand use, onset of hand stereotypes, abnormal gait, and growth failure. The course of the disease, in its classical form, is characterized by four stages. Three different atypical variants of the disease have been defined. Epilepsy has been reported in 60%-80% of patients with RTT; it differs among the various phenotypes and genotypes and its severity is an important contributor to the clinical severity of the disease. METHODS In this manuscript we reviewed literature on RTT, focusing on the different genetic entities, the correlation genotype-phenotype, and the peculiar epileptic phenotype associated to each of them. RESULTS Mutations in MECP2 gene, located on Xq28, account for 95% of typical RTT cases and 73.2% of atypical RTT. CDKL5 and FOXG1 are other genes identified as causative genes in atypical forms of RTT. In the last few years, a lot of new genes have been identified as causative genes for RTT phenotype. CONCLUSIONS Recognizing clinical and EEG patterns in different RTT variants may be useful in diagnosis and management of these patients.
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Affiliation(s)
- Francesca Felicia Operto
- Child Neuropsychiatry Unit, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Bari, Italy
| | - Roberta Mazza
- Child Neuropsychiatry Unit, Department of Basic Medical Sciences, Neuroscience and Sense Organs, University of Bari "Aldo Moro", Bari, Italy
| | | | - Alberto Verrotti
- Department of Pediatrics, University of L'Aquila, Coppito, Italy
| | - Giangennaro Coppola
- Child and Adolescent Neuropsychiatry, Medical School, University of Salerno, Fisciano, Italy
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Abstract
Elucidating the functions of a particular gene is paramount to the understanding of how its dysfunction contributes to disease. This is especially important when the gene is implicated in multiple different disorders. One such gene is methyl-CpG-binding protein 2 (MECP2), which has been most prominently associated with the neurodevelopmental disorder Rett syndrome, as well as major neuropsychiatric disorders such as autism and schizophrenia. Being initially identified as a transcriptional regulator that modulates gene expression and subsequently also shown to be involved in other molecular events, dysfunction of the MeCP2 protein has the potential to affect many cellular processes. In this chapter, we will briefly review the functions of the MeCP2 protein and how its mutations are implicated in Rett syndrome and other neuropsychiatric disorders. We will further discuss about the mouse models that have been generated to specifically dissect the function of MeCP2 in different cell types and brain regions. It is envisioned that such thorough and targeted examination of MeCP2 functions can aid in enlightening the role that it plays in normal and dysfunctional physiological systems.
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Affiliation(s)
- Eunice W M Chin
- Neuroscience and Mental Health Faculty, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Eyleen L K Goh
- Neuroscience and Mental Health Faculty, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.
- Department of Research, National Neuroscience Institute, Singapore, Singapore.
- Neuroscience Academic Clinical Programme, Singhealth Duke-NUS Academic Medical Center, Singapore, Singapore.
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KARIMZADEH P, KHEIROLLAHI M, HOUSHMAND SM, DADGAR S, ARYANI O, YAGHINI O. Clinical Feature and Genetics in Rett Syndrome: A Report on Iranian Patients. Iran J Child Neurol 2019; 13:37-51. [PMID: 31645865 PMCID: PMC6789083] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 08/15/2018] [Accepted: 09/27/2018] [Indexed: 11/21/2022]
Abstract
OBJECTIVES Rett syndrome is characterized by normal development for the first 6-18 months of life followed by the loss of fine and gross motor skills and the ability to engage in social interaction. In most patients, mutations are found in methyl CpG-binding protein 2 (MECP2) gene. We investigated the relation between Rett clinical diagnosis and mutations in MECP2. MATERIALS & METHODS Children suspected of Rett syndrome were invited to participate in this study. Twenty-three patients from the Mofid Hospital, Tehran, Iran suffered from classic Rett syndrome diagnostic criteria were enrolled in 2012. The severity of symptoms was assessed for all of them. The peripheral blood samples were collected in EDTA tubes and the genomic DNA was extracted using standard salting out method. The mutation of MEPC2 gene was studied using DNA sequencing method. RESULTS Overall, 11(47.8%) patients had MECP2 gene mutation, while 12 cases (52.2%) had no mutations. Changes in genetics were associated with phenotypical manifestations. The most prevalent mutation was p.v288 mainly associated with partially or uncontrolled seizures. CONCLUSION For the first time, we studies the Rett syndrome in terms of clinical manifestations and genetic changes in Iran.
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Affiliation(s)
- Parvaneh KARIMZADEH
- Pediatric Neurology ResearchCenter, Research Institute forChildren’s Health, Shahid Beheshti University of MedicalSciences, Tehran, Iran,Pediatric NeurologyDepartment, Mofid Children’s Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Majid KHEIROLLAHI
- Department of Medical Genetics, Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan, Iran.
| | - Seyed Massoud HOUSHMAND
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
| | - Sepideh DADGAR
- Department of Medical Genetic Medical Center and Faculty, Member of NIGEB, Tehran, Iran
| | - Omid ARYANI
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
| | - Omid YAGHINI
- Pediatric Neurology, Child growth and Development research center, Research Institute for Primordial Prevention of Noncommunicable Disease of Medical Genetic, Isfahan University of Medical Sciences. Isfahan, Iran.
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Zhang Q, Yang X, Wang J, Li J, Wu Q, Wen Y, Zhao Y, Zhang X, Yao H, Wu X, Yu S, Wei L, Bao X. Genomic mosaicism in the pathogenesis and inheritance of a Rett syndrome cohort. Genet Med 2019; 21:1330-8. [PMID: 30405208 DOI: 10.1038/s41436-018-0348-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [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] [Received: 08/11/2018] [Accepted: 10/17/2018] [Indexed: 01/01/2023] Open
Abstract
PURPOSE To determine the role of mosaicism in the pathogenesis and inheritance of Rett and Rett-like disorders. METHODS We recruited 471 Rett and Rett-like patients. Panel-sequencing targeting MECP2, CDKL5, and FOXG1 was performed. Mosaicism was quantified in 147 patients by a Bayesian genotyper. Candidates were validated by amplicon sequencing and digital PCR. Germline mosaicism of 21 fathers with daughters carrying pathogenic MECP2 variants was further quantified. RESULTS Pathogenic variants of MECP2/CDKL5/FOXG1 were found in 324/471 (68.7%) patients. Somatic MECP2 mosaicism was confirmed in 5/471 (1.1%) patients, including 3/18 males (16.7%) and 2/453 females (0.4%). Three of the five patients with somatic MECP2 mosaicism had mosaicism at MECP2-Arg106. Germline MECP2 mosaicism was detected in 5/21 (23.8%) fathers. CONCLUSION This is the first systematic screening of somatic and paternal germline MECP2 mosaicism at a cohort level. Our findings indicate that somatic MECP2 mosaicism contributes directly to the pathogenicity of Rett syndrome, especially in male patients. MECP2-Arg106 might be a mosaic hotspot. The high proportion of paternal germline MECP2 mosaicism indicates an underestimated mechanism underlying the paternal origin bias of MECP2 variants. Finally, this study provides an empirical foundation for future studies of genetic disorders caused by de novo variations of strong paternal origin.
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Carrette LLG, Blum R, Ma W, Kelleher RJ 3rd, Lee JT. Tsix-Mecp2 female mouse model for Rett syndrome reveals that low-level MECP2 expression extends life and improves neuromotor function. Proc Natl Acad Sci U S A 2018; 115:8185-90. [PMID: 30038001 DOI: 10.1073/pnas.1800931115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by a mutation in the X-linked methyl-CpG-binding protein 2 (MECP2). There is currently no disease-specific treatment, but MECP2 restoration through reactivation of the inactive X (Xi) has been of considerable interest. Progress toward an Xi-reactivation therapy has been hampered by a lack of suitable female mouse models. Because of cellular mosaicism due to random X-chromosome inactivation (XCI), Mecp2+/- heterozygous females develop only mild RTT. Here, we create an improved female mouse model by introducing a mutation in Tsix, the antisense regulator of XCI allelic choice. Tsix-Mecp2 mice show reduced MECP2 mosaicism and closely phenocopy the severely affected Mecp2-null males. Tsix-Mecp2 females demonstrate shortened lifespan, motor weakness, tremors, and gait disturbance. Intriguingly, they also exhibit repetitive behaviors, as is often seen in human RTT, including excessive grooming and biting that result in self-injury. With a Tsix allelic series, we vary MECP2 levels in brain and demonstrate a direct, but nonlinear correlation between MECP2 levels and phenotypic improvement. As little as 5-10% MECP2 restoration improves neuromotor function and extends lifespan five- to eightfold. Our study thus guides future pharmacological strategies and suggests that partial MECP2 restoration could have disproportionate therapeutic benefit.
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Abstract
The mechanisms of neuro-genetic disorders have been mostly investigated in the brain, however, for some pathologies, transcriptomic analysis in multiple tissues represent an opportunity and a challenge to understand the consequences of the genetic mutation. This is the case for Rett Syndrome (RTT): a neurodevelopmental disorder predominantly affecting females that is characterised by a loss of purposeful movements and language accompanied by gait abnormalities and hand stereotypies. Although the genetic aetiology is largely associated to Methyl CpG binding protein 2 (MECP2) mutations, linking the pathophysiology of RTT and its clinical symptoms to direct molecular mechanisms has been difficult.One approach used to study the consequences of MECP2 dysfunction in patients, is to perform transcriptomic analysis in tissues derived from RTT patients or Induced Pluripotent Stem cells. The growing affordability and efficiency of this approach has led to a far greater understanding of the complexities of RTT syndrome but is also raised questions about previously held convictions such as the regulatory role of MECP2, the effects of different molecular mechanisms in different tissues and role of X Chromosome Inactivation in RTT.In this review we consider the results of a number of different transcriptomic analyses in different patients-derived preparations to unveil specific trends in differential gene expression across the studies. Although the analyses present limitations- such as the limited sample size- overlaps exist across these studies, and they report dysregulations in three main categories: dendritic connectivity and synapse maturation, mitochondrial dysfunction, and glial cell activity.These observations have a direct application to the disorder and give insights on the altered mechanisms in RTT, with implications on potential diagnostic criteria and treatments.
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Affiliation(s)
- Stephen Shovlin
- Neuropsychiatric Genetics Research Group, Trinity Translational Medicine Institute- TTMI, St James Hospital, D8, Dublin, Ireland
| | - Daniela Tropea
- Neuropsychiatric Genetics Research Group, Trinity Translational Medicine Institute- TTMI, St James Hospital, D8, Dublin, Ireland
- Trinity College Institute of Neuroscience, TCIN, Loyd Building, Dublin2, Dublin, Ireland
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Mellios N, Feldman DA, Sheridan SD, Ip JP, Kwok S, Amoah SK, Rosen B, Rodriguez BA, Crawford B, Swaminathan R, Chou S, Li Y, Ziats M, Ernst C, Jaenisch R, Haggarty SJ, Sur M. MeCP2-regulated miRNAs control early human neurogenesis through differential effects on ERK and AKT signaling. Mol Psychiatry 2018; 23:1051-1065. [PMID: 28439102 PMCID: PMC5815944 DOI: 10.1038/mp.2017.86] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 02/12/2017] [Accepted: 02/28/2017] [Indexed: 12/15/2022]
Abstract
Rett syndrome (RTT) is an X-linked, neurodevelopmental disorder caused primarily by mutations in the methyl-CpG-binding protein 2 (MECP2) gene, which encodes a multifunctional epigenetic regulator with known links to a wide spectrum of neuropsychiatric disorders. Although postnatal functions of MeCP2 have been thoroughly investigated, its role in prenatal brain development remains poorly understood. Given the well-established importance of microRNAs (miRNAs) in neurogenesis, we employed isogenic human RTT patient-derived induced pluripotent stem cell (iPSC) and MeCP2 short hairpin RNA knockdown approaches to identify novel MeCP2-regulated miRNAs enriched during early human neuronal development. Focusing on the most dysregulated miRNAs, we found miR-199 and miR-214 to be increased during early brain development and to differentially regulate extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase and protein kinase B (PKB/AKT) signaling. In parallel, we characterized the effects on human neurogenesis and neuronal differentiation brought about by MeCP2 deficiency using both monolayer and three-dimensional (cerebral organoid) patient-derived and MeCP2-deficient neuronal culture models. Inhibiting miR-199 or miR-214 expression in iPSC-derived neural progenitors deficient in MeCP2 restored AKT and ERK activation, respectively, and ameliorated the observed alterations in neuronal differentiation. Moreover, overexpression of miR-199 or miR-214 in the wild-type mouse embryonic brains was sufficient to disturb neurogenesis and neuronal migration in a similar manner to Mecp2 knockdown. Taken together, our data support a novel miRNA-mediated pathway downstream of MeCP2 that influences neurogenesis via interactions with central molecular hubs linked to autism spectrum disorders.
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Affiliation(s)
- Nikolaos Mellios
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131,Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139,Correspondence to and
| | - Danielle A. Feldman
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Steven D. Sheridan
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139,Chemical Neurobiology Laboratory, Center for Human Genetic Research, Departments of Neurology & Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Jacque P.K. Ip
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Showming Kwok
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Stephen K. Amoah
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131
| | - Bess Rosen
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Brian A. Rodriguez
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131
| | - Benjamin Crawford
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Radha Swaminathan
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131
| | - Stephanie Chou
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Yun Li
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
| | - Mark Ziats
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892
| | - Carl Ernst
- Department of Psychiatry, McGill University, Montreal, QC Canada
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
| | - Stephen J. Haggarty
- Chemical Neurobiology Laboratory, Center for Human Genetic Research, Departments of Neurology & Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114
| | - Mriganka Sur
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA 02139,Correspondence to and
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Abstract
PURPOSE OF REVIEW This article reviews the current molecular genetic studies, which investigate the genetic causes of Rett syndrome or Rett-like phenotypes without a MECP2 mutation. RECENT FINDINGS As next generation sequencing becomes broadly available, especially whole exome sequencing is used in clinical diagnosis of the genetic causes of a wide spectrum of intellectual disability, autism, and encephalopathies. Patients who were diagnosed with Rett syndrome or Rett-like syndrome because of their phenotype but were negative for mutations in the MECP2, CDKL5 or FOXG1 genes were subjected to whole exome sequencing and the results of the last few years revealed yet 69 different genes. Many of these genes are involved in epigenetic gene regulation, chromatin shaping, neurotransmitter action or RNA transcription/translation. Genetic data also allows to investigate the individual genetic background of an individual patient, which can modify the severity of a genetic disorder. SUMMARY We conclude that the Rett syndrome phenotype has a much broader underlying genetic cause and the typical phenotype overlap with other genetic disorders. For proper genetic counselling, patient perspective and treatment it is important to include both phenotype and genetic information.
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Abstract
Rett syndrome (RTT) is a neurological disorder caused by mutations in the X-linked gene methyl-CpG-binding protein 2 (MECP2), a ubiquitously expressed transcriptional regulator. Despite remarkable scientific progress since its discovery, the mechanism by which MECP2 mutations cause RTT symptoms is largely unknown. Consequently, treatment options for patients are currently limited and centred on symptom relief. Thought to be an entirely neurological disorder, RTT research has focused on the role of MECP2 in the central nervous system. However, the variety of phenotypes identified in Mecp2 mutant mouse models and RTT patients implicate important roles for MeCP2 in peripheral systems. Here, we review the history of RTT, highlighting breakthroughs in the field that have led us to present day. We explore the current evidence supporting metabolic dysfunction as a component of RTT, presenting recent studies that have revealed perturbed lipid metabolism in the brain and peripheral tissues of mouse models and patients. Such findings may have an impact on the quality of life of RTT patients as both dietary and drug intervention can alter lipid metabolism. Ultimately, we conclude that a thorough knowledge of MeCP2's varied functional targets in the brain and body will be required to treat this complex syndrome.
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Affiliation(s)
- Stephanie M Kyle
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Neeti Vashi
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A1
| | - Monica J Justice
- Genetics and Genome Biology Program, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, Ontario, Canada M5G 0A4
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada M5S 1A1
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Valacchi G, Pecorelli A, Cervellati C, Hayek J. 4-hydroxynonenal protein adducts: Key mediator in Rett syndrome oxinflammation. Free Radic Biol Med 2017; 111:270-280. [PMID: 28063942 DOI: 10.1016/j.freeradbiomed.2016.12.045] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 12/24/2016] [Accepted: 12/30/2016] [Indexed: 12/13/2022]
Abstract
In the last 15 years a strong correlation between oxidative stress (OxS) and Rett syndrome (RTT), a rare neurodevelopmental disorder known to be caused in 95% of the cases, by a mutation in the methyl-CpG-binding protein 2 (MECP2) gene, has been well documented. Here, we revised, summarized and discussed the current knowledge on the role of lipid peroxidation byproducts, with special emphasis on 4-hydroxynonenal (4HNE), in RTT pathophysiology. The posttranslational modifications of proteins via 4HNE, known as 4HNE protein adducts (4NHE-PAs), causing detrimental effects on protein functions, appear to contribute to the clinical severity of the syndrome, since their levels increase significantly during the subsequent 4 clinical stages, reaching the maximum degree at stage 4, represented by a late motor deterioration. In addition, 4HNE-PA are only partially removed due to the compromised functionality of the proteasome activity, contributing therefore to the cellular damage in RTT. All this will lead to a characteristic subclinical inflammation, defined "OxInflammation", derived by a positive feedback loop between OxS byproducts and inflammatory mediators that in a long run further aggravates the clinical features of RTT patients. Therefore, in a pathology completely orphan of any therapy, aiming 4HNE as a therapeutic target could represent a coadjuvant treatment with some beneficial impact in these patients..
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Affiliation(s)
- Giuseppe Valacchi
- Plants for Human Health Institute, Department of Animal Sciences, NC State University, NC Research Campus, 600 Laureate Way, Kannapolis, NC 28081, USA; Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy.
| | - Alessandra Pecorelli
- Plants for Human Health Institute, Department of Animal Sciences, NC State University, NC Research Campus, 600 Laureate Way, Kannapolis, NC 28081, USA; Department of Life Sciences and Biotechnology, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Carlo Cervellati
- Department of Biomedical and Specialist Surgical Sciences, Section of Medical Biochemistry, Molecular Biology and Genetics, University of Ferrara, Via Luigi Borsari 46, 44121 Ferrara, Italy
| | - Joussef Hayek
- Child Neuropsychiatry Unit, University Hospital, AOUS, Viale Mario Bracci, 53100 Siena, Italy
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45
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Bebensee DF, Can K, Müller M. Increased Mitochondrial Mass and Cytosolic Redox Imbalance in Hippocampal Astrocytes of a Mouse Model of Rett Syndrome: Subcellular Changes Revealed by Ratiometric Imaging of JC-1 and roGFP1 Fluorescence. Oxid Med Cell Longev 2017; 2017:3064016. [PMID: 28894505 DOI: 10.1155/2017/3064016] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 06/16/2017] [Accepted: 06/27/2017] [Indexed: 12/21/2022]
Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder with mutations in the MECP2 gene. Mostly girls are affected, and an apparently normal development is followed by cognitive impairment, motor dysfunction, epilepsy, and irregular breathing. Various indications suggest mitochondrial dysfunction. In Rett mice, brain ATP levels are reduced, mitochondria are leaking protons, and respiratory complexes are dysregulated. Furthermore, we found in MeCP2-deficient mouse (Mecp2−/y) hippocampus an intensified mitochondrial metabolism and ROS generation. We now used emission ratiometric 2-photon imaging to assess mitochondrial morphology, mass, and membrane potential (ΔΨm) in Mecp2−/y hippocampal astrocytes. Cultured astrocytes were labeled with the ΔΨm marker JC-1, and semiautomated analyses yielded the number of mitochondria per cell, their morphology, and ΔΨm. Mecp2−/y astrocytes contained more mitochondria than wild-type (WT) cells and were more oxidized. Mitochondrial size, ΔΨm, and vulnerability to pharmacological challenge did not differ. The antioxidant Trolox opposed the oxidative burden and decreased the mitochondrial mass, thereby dampening the differences among WT and Mecp2−/y astrocytes; mitochondrial size and ΔΨm were not markedly affected. In conclusion, mitochondrial alterations and redox imbalance in RTT also involve astrocytes. Mitochondria are more numerous in Mecp2−/y than in WT astrocytes. As this genotypic difference is abolished by Trolox, it seems linked to the oxidative stress in RTT.
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Martin P. Pain in Rett syndrome: peculiarities in pain processing and expression, liability to pain causing disorders and diseases, and specific aspects of pain assessment. Advances in Autism 2017. [DOI: 10.1108/aia-02-2017-0003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Peter Martin
- Epilepsiezentrum Kork, Seguin-Klinik, Kehl-Kork, Germany
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Zhang Q, Zhao Y, Bao X, Luo J, Zhang X, Li J, Wei L, Wu X. Familial cases and male cases with MECP2 mutations. Am J Med Genet B Neuropsychiatr Genet 2017; 174:451-457. [PMID: 28394482 PMCID: PMC5485058 DOI: 10.1002/ajmg.b.32534] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 02/06/2017] [Indexed: 12/03/2022]
Abstract
This is the first report of Chinese familial cases with Rett syndrome (RTT) or X-linked mental retardation (XLMR). RTT is a neurodevelopmental disorder that almost exclusively affects females. Most RTT cases are sporadic. We have studied eight cases with MECP2 mutations in six Chinese families, including three females and five males with RTT or XLMR. All shared identical MECP2 mutations with their mothers. The three females fulfilled the diagnostic criteria for RTT, while the five males were XLMR. A random X-chromosome inactive (XCI) pattern was seen in all the three female patients and two mothers while a skewed XCI in the rest four mothers. The clinical manifestations and pathogenic gene spectrum between male and female patients were different. The different MECP2 mutations and different XCI pattern may be the determinants of the phenotypic heterogeneity between the family members.
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Affiliation(s)
- Qingping Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Ying Zhao
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xinhua Bao
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Jinjun Luo
- Departments of Neurology and PharmacologyLewis Katz School of Medicine at Temple UniversityPhiladelphiaPennsylvania
| | - Xiaoying Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Jiarui Li
- State Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking University, Center for BioinformaticsBeijingChina
| | - Liping Wei
- State Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking University, Center for BioinformaticsBeijingChina
| | - Xiru Wu
- Department of PediatricsPeking University First HospitalBeijingChina
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Vogel Ciernia A, Pride MC, Durbin-Johnson B, Noronha A, Chang A, Yasui DH, Crawley JN, LaSalle JM. Early motor phenotype detection in a female mouse model of Rett syndrome is improved by cross-fostering. Hum Mol Genet 2017; 26:1839-1854. [PMID: 28334953 PMCID: PMC6075042 DOI: 10.1093/hmg/ddx087] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 03/01/2017] [Accepted: 03/03/2017] [Indexed: 12/14/2022] Open
Abstract
Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by mutations in the gene encoding methyl CpG binding protein 2 (MeCP2) that occur sporadically in 1:10,000 female births. RTT is characterized by a period of largely normal development followed by regression in language and motor skills at 6-18 months of age. Mecp2 mutant mice recapitulate many of the clinical features of RTT, but the majority of behavioral assessments have been conducted in male Mecp2 hemizygous null mice as offspring of heterozygous dams. Given that RTT patients are predominantly female, we conducted a systematic analysis of developmental milestones, sensory abilities, and motor deficits, following the longitudinal decline of function from early postnatal to adult ages in female Mecp2 heterozygotes of the conventional Bird line (Mecp2tm1.1bird-/+), as compared to their female wildtype littermate controls. Further, we assessed the impact of postnatal maternal environment on developmental milestones and behavioral phenotypes. Cross-fostering to CD1 dams accelerated several developmental milestones independent of genotype, and induced earlier onset of weight gain in adult female Mecp2tm1.1bird-/+ mice. Cross-fostering improved the sensitivity of a number of motor behaviors that resulted in observable deficits in Mecp2tm1.1bird-/+ mice at much earlier (6-7 weeks) ages than were previously reported (6-9 months). Our findings indicate that female Mecp2tm1.1bird-/+ mice recapitulate many of the motor aspects of RTT syndrome earlier than previously appreciated. In addition, rearing conditions may impact the phenotypic severity and improve the ability to detect genotype differences in female Mecp2 mutant mice.
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Affiliation(s)
| | | | | | - Adriana Noronha
- Medical Microbiology and Immunology
- Genome Center
- MIND Institute
| | - Alene Chang
- Medical Microbiology and Immunology
- Genome Center
- MIND Institute
| | - Dag H. Yasui
- Medical Microbiology and Immunology
- Genome Center
- MIND Institute
- Department of Psychiatry and Behavioral Sciences
| | | | - Janine M. LaSalle
- Medical Microbiology and Immunology
- Genome Center
- MIND Institute
- Department of Psychiatry and Behavioral Sciences
- Center for Children's Environmental Health, University of California, Davis, UC Davis, CA, USA
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Gomathi M, Balachandar V. Novel therapeutic approaches: Rett syndrome and human induced pluripotent stem cell technology. Stem Cell Investig 2017; 4:20. [PMID: 28447035 DOI: 10.21037/sci.2017.02.11] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [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: 01/26/2017] [Accepted: 02/21/2017] [Indexed: 01/28/2023]
Abstract
Recent advances in induced pluripotent stem cell (iPSC) technology target screening and discovering of therapeutic agents for the possible cure of human diseases. Human induced pluripotent stem cells (hiPSC) are the right kind of platform for testing potency of specific active compounds. Ayurveda, the Indian traditional system of medicine developed between 2,500 and 500 BC, is a science involving the intelligent formulations of herbs and minerals. It can serve as a "goldmine" for novel neuroprotective agents used for centuries to treat neurological disorders. This review discusses limitations in screening drugs for neurological disorders and the advantages offered by hiPSC integrated with Indian traditional system of medicine. We begin by describing the current state of hiPSC technology in research on Rett syndrome (RTT) followed by the current controversies in RTT research combined with the emergence of patient-specific hiPSC that indicate an urgent need for researchers to understand the etiology and drug mechanism. We conclude by offering recommendations to reinforce the screening of active compounds present in the ayurvedic medicines using the human induced pluripotent neural model system for research involving drug discovery for RTT. This integrative approach will fill the current knowledge gap in the traditional medicines and drug discovery.
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Affiliation(s)
- Mohan Gomathi
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
| | - Vellingiri Balachandar
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore-641 046, Tamil Nadu, India
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Kovanova EN, Bihunyak ТV, Bihuniak KO, Kulitska MI. EPIGENETIC AND GENETIC ASPECTS OF RETT SYNDROME, ASSOCIATED WITH EPIMUTATION C → mC IN THE TRANSGENERATIONAL INHERITANCE. WOMAB 2017; 13:183. [DOI: 10.26724/2079-8334-2017-4-62-183-186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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