1
|
Catalano F, Santorelli D, Astegno A, Favretto F, D'Abramo M, Del Giudice A, De Sciscio ML, Troilo F, Giardina G, Di Matteo A, Travaglini-Allocatelli C. Conformational and dynamic properties of the KH1 domain of FMRP and its fragile X syndrome linked G266E variant. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2024; 1872:141019. [PMID: 38641086 DOI: 10.1016/j.bbapap.2024.141019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/26/2024] [Accepted: 04/14/2024] [Indexed: 04/21/2024]
Abstract
The Fragile X messenger ribonucleoprotein (FMRP) is a multi-domain protein involved in interactions with various macromolecules, including proteins and coding/non-coding RNAs. The three KH domains (KH0, KH1 and KH2) within FMRP are recognized for their roles in mRNA binding. In the context of Fragile X syndrome (FXS), over-and-above CGG triplet repeats expansion, three specific point mutations have been identified, each affecting one of the three KH domains (R138QKH0, G266EKH1, and I304NKH2) resulting in the expression of non-functional FMRP. This study aims to elucidate the molecular mechanism underlying the loss of function associated with the G266EKH1 pathological variant. We investigate the conformational and dynamic properties of the isolated KH1 domain and the two KH1 site-directed mutants G266EKH1 and G266AKH1. Employing a combined in vitro and in silico approach, we reveal that the G266EKH1 variant lacks the characteristic features of a folded domain. This observation provides an explanation for functional impairment observed in FMRP carrying the G266E mutation within the KH1 domain, as it renders the domain unable to fold properly. Molecular Dynamics simulations suggest a pivotal role for residue 266 in regulating the structural stability of the KH domains, primarily through stabilizing the α-helices of the domain. Overall, these findings enhance our comprehension of the molecular basis for the dysfunction associated with the G266EKH1 variant in FMRP.
Collapse
Affiliation(s)
- Flavia Catalano
- Department of Biochemical Sciences, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Daniele Santorelli
- Department of Biochemical Sciences, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Filippo Favretto
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, Verona 37134, Italy
| | - Marco D'Abramo
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Alessandra Del Giudice
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Maria Laura De Sciscio
- Department of Chemistry, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Francesca Troilo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, Rome 00185, Italy
| | - Giorgio Giardina
- Department of Biochemical Sciences, Sapienza University of Rome, P.le Aldo Moro 5, Rome 00185, Italy
| | - Adele Di Matteo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, Rome 00185, Italy.
| | | |
Collapse
|
2
|
Hayden AN, Brandel KL, Merlau PR, Vijayakumar P, Leptich EJ, Pietryk EW, Gaytan ES, Ni CW, Chao HT, Rosenfeld JA, Arey RN. Behavioral screening of conserved RNA-binding proteins reveals CEY-1/YBX RNA-binding protein dysfunction leads to impairments in memory and cognition. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.05.574402. [PMID: 38260399 PMCID: PMC10802296 DOI: 10.1101/2024.01.05.574402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
RNA-binding proteins (RBPs) regulate translation and plasticity which are required for memory. RBP dysfunction has been linked to a range of neurological disorders where cognitive impairments are a key symptom. However, of the 2,000 RBPs in the human genome, many are uncharacterized with regards to neurological phenotypes. To address this, we used the model organism C. elegans to assess the role of 20 conserved RBPs in memory. We identified eight previously uncharacterized memory regulators, three of which are in the C. elegans Y-Box (CEY) RBP family. Of these, we determined that cey-1 is the closest ortholog to the mammalian Y-Box (YBX) RBPs. We found that CEY-1 is both necessary in the nervous system for memory ability and sufficient to increase memory. Leveraging human datasets, we found both copy number variation losses and single nucleotide variants in YBX1 and YBX3 in individuals with neurological symptoms. We identified one predicted deleterious YBX3 variant of unknown significance, p.Asn127Tyr, in two individuals with neurological symptoms. Introducing this variant into endogenous cey-1 locus caused memory deficits in the worm. We further generated two humanized worm lines expressing human YBX3 or YBX1 at the cey-1 locus to test evolutionary conservation of YBXs in memory and the potential functional significance of the p.Asn127Tyr variant. Both YBX1/3 can functionally replace cey-1, and introduction of p.Asn127Tyr into the humanized YBX3 locus caused memory deficits. Our study highlights the worm as a model to reveal memory regulators and identifies YBX dysfunction as a potential new source of rare neurological disease.
Collapse
Affiliation(s)
- Ashley N Hayden
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
| | - Katie L Brandel
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
| | - Paul R Merlau
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
| | | | - Emily J Leptich
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
| | - Edward W Pietryk
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030
| | - Elizabeth S Gaytan
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
- Postbaccalaureate Research Education Program, Baylor College of Medicine, Houston, TX, 77030
| | - Connie W Ni
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
- Department of Neuroscience, Rice University, Houston, TX 77005
| | - Hsiao-Tuan Chao
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030
- Department of Pediatrics, Division of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, TX, 77030
- Cain Pediatric Neurology Research Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, 77030
- McNair Medical Institute, The Robert and Janice McNair Foundation, Houston, TX, 77030
| | - Jill A Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030
- Baylor Genetics Laboratories, Houston, TX 77021
| | - Rachel N Arey
- Center for Precision Environmental Health, Baylor College of Medicine, Houston, TX, 77030
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, 77030
| |
Collapse
|
3
|
Jin C, Zhang X, Lei Q, Chen P, Hu H, Shen S, Liu J, Ye S. Case report: genetic analysis of a novel frameshift mutation in FMR1 gene in a Chinese family. Front Genet 2023; 14:1228682. [PMID: 37745859 PMCID: PMC10512415 DOI: 10.3389/fgene.2023.1228682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 08/21/2023] [Indexed: 09/26/2023] Open
Abstract
Fragile X syndrome (FXS) [OMIM 300624] is a common X-linked inherited syndrome with an incidence only second to that of trisomy 21. More than 95% of fragile X syndrome is caused by reduced or absent fragile X intellectual disability protein 1 (FMRP) synthesis due to dynamic mutation expansion of the CGG triplet repeat in the 5'UTR and abnormal methylation of the FMR1 (fragile X messenger ribonucleoprotein 1) gene [OMIM 309550]. Less than 5% of cases are caused by abnormal function of the FMRP due to point mutations or deletions in the FMR1 gene. In a proband with clinical suspicion of FXS and no CGG duplication, we found the presence of c.585_586del (p.Lys195AsnfsTer8) in exon 7 of the FMR1 gene using whole exome sequencing (WES). This variant resulted in frameshift and a premature stop codon after 8 aberrant amino acids. This variant is a novel pathogenic mutation, as determined by pedigree analysis, which has not been reported in any database or literature.
Collapse
Affiliation(s)
- Chunlei Jin
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Xiangdong Zhang
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Qiang Lei
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Penglong Chen
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Hui Hu
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Shuangshuang Shen
- Center of Medical Prenatal Diagnosis, Jinhua Maternity and Child Health Care Hospital, Jinhua, China
| | - Jiao Liu
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| | - Shixuanbao Ye
- Center of Medical Prenatal Diagnosis, Lishui Maternity and Child Health Care Hospital, Lishui, China
| |
Collapse
|
4
|
Elhawary NA, AlJahdali IA, Abumansour IS, Azher ZA, Falemban AH, Madani WM, Alosaimi W, Alghamdi G, Sindi IA. Phenotypic variability to medication management: an update on fragile X syndrome. Hum Genomics 2023; 17:60. [PMID: 37420260 DOI: 10.1186/s40246-023-00507-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023] Open
Abstract
This review discusses the discovery, epidemiology, pathophysiology, genetic etiology, molecular diagnosis, and medication-based management of fragile X syndrome (FXS). It also highlights the syndrome's variable expressivity and common comorbid and overlapping conditions. FXS is an X-linked dominant disorder associated with a wide spectrum of clinical features, including but not limited to intellectual disability, autism spectrum disorder, language deficits, macroorchidism, seizures, and anxiety. Its prevalence in the general population is approximately 1 in 5000-7000 men and 1 in 4000-6000 women worldwide. FXS is associated with the fragile X messenger ribonucleoprotein 1 (FMR1) gene located at locus Xq27.3 and encodes the fragile X messenger ribonucleoprotein (FMRP). Most individuals with FXS have an FMR1 allele with > 200 CGG repeats (full mutation) and hypermethylation of the CpG island proximal to the repeats, which silences the gene's promoter. Some individuals have mosaicism in the size of the CGG repeats or in hypermethylation of the CpG island, both produce some FMRP and give rise to milder cognitive and behavioral deficits than in non-mosaic individuals with FXS. As in several monogenic disorders, modifier genes influence the penetrance of FMR1 mutations and FXS's variable expressivity by regulating the pathophysiological mechanisms related to the syndrome's behavioral features. Although there is no cure for FXS, prenatal molecular diagnostic testing is recommended to facilitate early diagnosis. Pharmacologic agents can reduce some behavioral features of FXS, and researchers are investigating whether gene editing can be used to demethylate the FMR1 promoter region to improve patient outcomes. Moreover, clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 and developed nuclease defective Cas9 (dCas9) strategies have promised options of genome editing in gain-of-function mutations to rewrite new genetic information into a specified DNA site, are also being studied.
Collapse
Affiliation(s)
- Nasser A Elhawary
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia.
| | - Imad A AlJahdali
- Department of Community Medicine, College of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Iman S Abumansour
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Zohor A Azher
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Alaa H Falemban
- Department of Pharmacology and Toxicology, College of Medicine, Umm Al-Qura University, Mecca, 24382, Saudi Arabia
| | - Wefaq M Madani
- Department of Hematology and Immunology, Faculty of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Ghydda Alghamdi
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Ikhlas A Sindi
- Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Preparatory Year Program, Batterjee Medical College, Jeddah, 21442, Saudi Arabia
| |
Collapse
|
5
|
Wright SE, Todd PK. Native functions of short tandem repeats. eLife 2023; 12:e84043. [PMID: 36940239 PMCID: PMC10027321 DOI: 10.7554/elife.84043] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 03/08/2023] [Indexed: 03/21/2023] Open
Abstract
Over a third of the human genome is comprised of repetitive sequences, including more than a million short tandem repeats (STRs). While studies of the pathologic consequences of repeat expansions that cause syndromic human diseases are extensive, the potential native functions of STRs are often ignored. Here, we summarize a growing body of research into the normal biological functions for repetitive elements across the genome, with a particular focus on the roles of STRs in regulating gene expression. We propose reconceptualizing the pathogenic consequences of repeat expansions as aberrancies in normal gene regulation. From this altered viewpoint, we predict that future work will reveal broader roles for STRs in neuronal function and as risk alleles for more common human neurological diseases.
Collapse
Affiliation(s)
- Shannon E Wright
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- Neuroscience Graduate Program, University of Michigan–Ann ArborAnn ArborUnited States
- Department of Neuroscience, Picower InstituteCambridgeUnited States
| | - Peter K Todd
- Department of Neurology, University of Michigan–Ann ArborAnn ArborUnited States
- VA Ann Arbor Healthcare SystemAnn ArborUnited States
| |
Collapse
|
6
|
Segal O, Kowal T, Banet-Levi Y, Gabis LV. Executive Function and Working Memory Deficits in Females with Fragile X Premutation. Life (Basel) 2023; 13:life13030813. [PMID: 36983968 PMCID: PMC10053193 DOI: 10.3390/life13030813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/27/2023] [Accepted: 03/15/2023] [Indexed: 03/19/2023] Open
Abstract
The Fragile X premutation is a genetic instability of the FMR1 gene caused by 55–199 recurrences of the CGG sequence, whereas there are only 7–54 repeats of the CGG sequence in the normal condition. While males with the premutation of Fragile X were found to have difficulties in executive functions and working memory, little data have been collected on females. This study is among the first to address executive functions and phonological memory in females with the Fragile X premutation. Twenty-three female carriers aged 20–55 years and twelve non carrier females matched in age and levels of education (in years) participated in this study. Executive functions and phonological memory were assessed using the self-report questionnaire The Behavior Rating Inventory of Executive Function (BRIEF) and behavioral measures (nonword repetitions, forward and backward digit span). Females who were carriers of the premutation of the FMR1 gene reported less efficient executive functions in the BRIEF questionnaire compared to the control group. In addition, a relationship was found between the number of repetitions on the CGG sequence of nucleotides, nonword repetitions, and forward digit span. The findings suggest that the premutation of Fragile X in females affects their performance of executive functions and may have impact on everyday functioning.
Collapse
Affiliation(s)
- Osnat Segal
- Department of Communication Disorders, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv 6997801, Israel
- Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv 6997801, Israel
- Correspondence: ; Tel.: +972-522998404
| | - Tamar Kowal
- Department of Communication Disorders, The Stanley Steyer School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv 6997801, Israel
| | | | - Lidia V. Gabis
- Keshet Autism Center Maccabi Wolfson, Holon 5822012, Israel
- Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv 6997801, Israel
| |
Collapse
|
7
|
Folding Mechanism and Aggregation Propensity of the KH0 Domain of FMRP and Its R138Q Pathological Variant. Int J Mol Sci 2022; 23:ijms232012178. [PMID: 36293035 PMCID: PMC9603430 DOI: 10.3390/ijms232012178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/05/2022] [Accepted: 10/08/2022] [Indexed: 11/16/2022] Open
Abstract
The K-homology (KH) domains are small, structurally conserved domains found in proteins of different origins characterized by a central conserved βααβ “core” and a GxxG motif in the loop between the two helices of the KH core. In the eukaryotic KHI type, additional αβ elements decorate the “core” at the C-terminus. Proteins containing KH domains perform different functions and several diseases have been associated with mutations in these domains, including those in the fragile X mental retardation protein (FMRP). FMRP is an RNA-binding protein crucial for the control of RNA metabolism whose lack or mutations lead to fragile X syndrome (FXS). Among missense mutations, the R138Q substitution is in the KH0 degenerated domain lacking the classical GxxG motif. By combining equilibrium and kinetic experiments, we present a characterization of the folding mechanism of the KH0 domain from the FMRP wild-type and of the R138Q variant showing that in both cases the folding mechanism implies the accumulation of an on-pathway transient intermediate. Moreover, by exploiting a battery of biophysical techniques, we show that the KH0 domain has the propensity to form amyloid-like aggregates in mild conditions in vitro and that the R138Q mutation leads to a general destabilization of the protein and to an increased fibrillogenesis propensity.
Collapse
|
8
|
Berry-Kravis E. Disease-Targeted Treatment Translation in Fragile X Syndrome as a Model for Neurodevelopmental Disorders. J Child Neurol 2022; 37:797-812. [PMID: 35791522 DOI: 10.1177/08830738221089740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Fragile X syndrome (FXS), the most common monogenic cause of intellectual disability and autism spectrum disorder, has been one of the first neurodevelopmental disorders in which molecular and neuronal mechanisms of disease were identified, leading to the concept of targeting the underlying disease to reverse symptoms. Translating findings in basic science and animal models to humans with FXS has proven difficult. These challenges have prompted the FXS field to organize to build interlocking projects and initiatives to improve consistency of supportive care, make clinical research accessible to families, generate collaborative research on natural history, outcome measures and biomarkers, and create clinical trial consortia and novel trial designs. This work has resulted in improved success in recent clinical trials, providing key steps toward regulatory approval of disease-targeted treatments for FXS. Progress in the FXS field has informed translation of transformative new disease-targeted therapies for other monogenic neurodevelopmental disorders.
Collapse
Affiliation(s)
- Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurological Sciences, Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, USA
| |
Collapse
|
9
|
Liang Q, Liu Y, Liu Y, Duan R, Meng W, Zhan J, Xia J, Mao A, Liang D, Wu L. Comprehensive Analysis of Fragile X Syndrome: Full Characterization of the FMR1 Locus by Long-Read Sequencing. Clin Chem 2022; 68:1529-1540. [PMID: 36171182 DOI: 10.1093/clinchem/hvac154] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/21/2022] [Indexed: 11/14/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) is the most frequent cause of inherited X-linked intellectual disability. Conventional FXS genetic testing methods mainly focus on FMR1 CGG expansions and fail to identify AGG interruptions, rare intragenic variants, and large gene deletions. METHODS A long-range PCR and long-read sequencing-based assay termed comprehensive analysis of FXS (CAFXS) was developed and evaluated in Coriell and clinical samples by comparing to Southern blot analysis and triplet repeat-primed PCR (TP-PCR). RESULTS CAFXS accurately detected the number of CGG repeats in the range of 93 to at least 940 with mass fraction of 0.5% to 1% in the background of normal alleles, which was 2-4-fold analytically more sensitive than TP-PCR. All categories of mutations detected by control methods, including full mutations in 30 samples, were identified by CAFXS for all 62 clinical samples. CAFXS accurately determined AGG interruptions in all 133 alleles identified, even in mosaic alleles. CAFXS successfully identified 2 rare intragenic variants including the c.879A > C variant in exon 9 and a 697-bp microdeletion flanking upstream of CGG repeats, which disrupted primer annealing in TP-PCR assay. In addition, CAFXS directly determined the breakpoints of a 237.1-kb deletion and a 774.0-kb deletion encompassing the entire FMR1 gene in 2 samples. CONCLUSIONS Long-read sequencing-based CAFXS represents a comprehensive assay for identifying FMR1 CGG expansions, AGG interruptions, rare intragenic variants, and large gene deletions, which greatly improves the genetic screening and diagnosis for FXS.
Collapse
Affiliation(s)
- Qiaowei Liang
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Yingdi Liu
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Yaning Liu
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Ranhui Duan
- Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Wanli Meng
- Berry Genomics Corporation, Beijing, China
| | | | - Jiahui Xia
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China
| | - Aiping Mao
- Berry Genomics Corporation, Beijing, China
| | - Desheng Liang
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Lingqian Wu
- Department of Medical Genetics, Hunan Jiahui Genetics Hospital, Changsha, Hunan, China.,Center for Medical Genetics and Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| |
Collapse
|
10
|
Laroui A, Galarneau L, Abolghasemi A, Benachenhou S, Plantefève R, Bouchouirab FZ, Lepage JF, Corbin F, Çaku A. Clinical significance of matrix metalloproteinase-9 in Fragile X Syndrome. Sci Rep 2022; 12:15386. [PMID: 36100610 PMCID: PMC9470743 DOI: 10.1038/s41598-022-19476-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/30/2022] [Indexed: 11/12/2022] Open
Abstract
High plasma matrix metalloproteases-9 (MMP-9) levels have been reported in Fragile X Syndrome in a limited number of animal and human studies. Since the results obtained are method-dependent and not directly comparable, the clinical utility of MMP-9 measurement in FXS remains unclear. This study aimed to compare quantitative gel zymography and ELISA and to determine which method better discriminates abnormal MMP-9 levels of individuals with FXS from healthy controls and correlates with the clinical profile. The active and total forms of MMP-9 were quantified respectively, by gel zymography and ELISA in a cohort of FXS (n = 23) and healthy controls (n = 20). The clinical profile was assessed for the FXS group using the Aberrant Behavior Checklist FXS adapted version (ABC-CFX), Adaptive Behavior Assessment System (ABAS), Social Communication Questionnaire (SCQ), and Anxiety Depression and Mood Scale questionnaires. Method comparison showed a disagreement between gel zymography and ELISA with a constant error of − 0.18 [95% CI: − 0.35 to − 0.02] and a proportional error of 2.31 [95% CI: 1.53 to 3.24]. Plasma level of MMP-9 active form was significantly higher in FXS (n = 12) as compared to their age-sex and BMI matched controls (n = 12) (p = 0.039) and correlated with ABC-CFX (rs = 0.60; p = 0.039) and ADAMS (rs = 0.57; p = 0.043) scores. As compared to the plasma total form, the plasma MMP-9 active form better enables the discrimination of individuals with FXS from controls and correlates with the clinical profile. Our results highlight the importance of choosing the appropriate method to quantify plasma MMP-9 in future FXS clinical studies.
Collapse
|
11
|
Jiraanont P, Manor E, Tabatadze N, Zafarullah M, Mendoza G, Melikishvili G, Tassone F. De Novo Large Deletion Leading to Fragile X Syndrome. Front Genet 2022; 13:884424. [PMID: 35646065 PMCID: PMC9130735 DOI: 10.3389/fgene.2022.884424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/13/2022] [Indexed: 11/13/2022] Open
Abstract
Fragile X syndrome (FXS) is the most frequent cause of X-linked inherited intellectual disabilities (ID) and the most frequent monogenic form of autism spectrum disorders. It is caused by an expansion of a CGG trinucleotide repeat located in the 5'UTR of the FMR1 gene, resulting in the absence of the fragile X mental retardation protein, FMRP. Other mechanisms such as deletions or point mutations of the FMR1 gene have been described and account for approximately 1% of individuals with FXS. Here, we report a 7-year-old boy with FXS with a de novo deletion of approximately 1.1 Mb encompassing several genes, including the FMR1 and the ASFMR1 genes, and several miRNAs, whose lack of function could result in the observed proband phenotypes. In addition, we also demonstrate that FMR4 completely overlaps with ASFMR1, and there are no sequencing differences between both transcripts (i.e., ASFMR1/FMR4 throughout the article).
Collapse
Affiliation(s)
- Poonnada Jiraanont
- Faculty of Medicine, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand
| | - Esther Manor
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheba, Israel.,Genetics Institute, Soroka Medical Center, Beersheba, Israel
| | - Nazi Tabatadze
- Department of Pediatrics, MediClub Georgia Medical Center, Tbilisi, Georgia
| | - Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA, United States
| | - Guadalupe Mendoza
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA, United States
| | - Gia Melikishvili
- Department of Pediatrics, MediClub Georgia Medical Center, Tbilisi, Georgia
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, School of Medicine, University of California, Davis, Sacramento, CA, United States.,UC Davis MIND Institute, UC Davis Health, Sacramento, CA, United States
| |
Collapse
|
12
|
Curnow E, Wang Y. New Animal Models for Understanding FMRP Functions and FXS Pathology. Cells 2022; 11:1628. [PMID: 35626665 PMCID: PMC9140010 DOI: 10.3390/cells11101628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/03/2022] [Accepted: 05/09/2022] [Indexed: 11/16/2022] Open
Abstract
Fragile X encompasses a range of genetic conditions, all of which result as a function of changes within the FMR1 gene and abnormal production and/or expression of the FMR1 gene products. Individuals with Fragile X syndrome (FXS), the most common heritable form of intellectual disability, have a full-mutation sequence (>200 CGG repeats) which brings about transcriptional silencing of FMR1 and loss of FMR protein (FMRP). Despite considerable progress in our understanding of FXS, safe, effective, and reliable treatments that either prevent or reduce the severity of the FXS phenotype have not been approved. While current FXS animal models contribute their own unique understanding to the molecular, cellular, physiological, and behavioral deficits associated with FXS, no single animal model is able to fully recreate the FXS phenotype. This review will describe the status and rationale in the development, validation, and utility of three emerging animal model systems for FXS, namely the nonhuman primate (NHP), Mongolian gerbil, and chicken. These developing animal models will provide a sophisticated resource in which the deficits in complex functions of perception, action, and cognition in the human disorder are accurately reflected and aid in the successful translation of novel therapeutics and interventions to the clinic setting.
Collapse
Affiliation(s)
- Eliza Curnow
- REI Division, Department of ObGyn, University of Washington, Seattle, WA 98195, USA
- Washington National Primate Research Center, University of Washington, Seattle, WA 98195, USA
| | - Yuan Wang
- Program in Neuroscience, Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| |
Collapse
|
13
|
Kehinde TA, Bhatia A, Olarewaju B, Shoaib MZ, Mousa J, Osundiji MA. Syndromic obesity with neurodevelopmental delay: Opportunities for targeted interventions. Eur J Med Genet 2022; 65:104443. [DOI: 10.1016/j.ejmg.2022.104443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/09/2022] [Accepted: 01/22/2022] [Indexed: 01/01/2023]
|
14
|
Schröder C, Horsthemke B, Depienne C. GC-rich repeat expansions: associated disorders and mechanisms. MED GENET-BERLIN 2021; 33:325-335. [PMID: 38835438 PMCID: PMC11006399 DOI: 10.1515/medgen-2021-2099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 11/12/2021] [Indexed: 06/06/2024]
Abstract
Noncoding repeat expansions are a well-known cause of genetic disorders mainly affecting the central nervous system. Missed by most standard technologies used in routine diagnosis, pathogenic noncoding repeat expansions have to be searched for using specific techniques such as repeat-primed PCR or specific bioinformatics tools applied to genome data, such as ExpansionHunter. In this review, we focus on GC-rich repeat expansions, which represent at least one third of all noncoding repeat expansions described so far. GC-rich expansions are mainly located in regulatory regions (promoter, 5' untranslated region, first intron) of genes and can lead to either a toxic gain-of-function mediated by RNA toxicity and/or repeat-associated non-AUG (RAN) translation, or a loss-of-function of the associated gene, depending on their size and their methylation status. We herein review the clinical and molecular characteristics of disorders associated with these difficult-to-detect expansions.
Collapse
Affiliation(s)
- Christopher Schröder
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Bernhard Horsthemke
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| |
Collapse
|
15
|
Bleuzé L, Triaca V, Borreca A. FMRP-Driven Neuropathology in Autistic Spectrum Disorder and Alzheimer's disease: A Losing Game. Front Mol Biosci 2021; 8:699613. [PMID: 34760921 PMCID: PMC8573832 DOI: 10.3389/fmolb.2021.699613] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/24/2021] [Indexed: 12/28/2022] Open
Abstract
Fragile X mental retardation protein (FMRP) is an RNA binding protein (RBP) whose absence is essentially associated to Fragile X Syndrome (FXS). As an RNA Binding Protein (RBP), FMRP is able to bind and recognize different RNA structures and the control of specific mRNAs is important for neuronal synaptic plasticity. Perturbations of this pathway have been associated with the autistic spectrum. One of the FMRP partners is the APP mRNA, the main protagonist of Alzheimer’s disease (AD), thereby regulating its protein level and metabolism. Therefore FMRP is associated to two neurodevelopmental and age-related degenerative conditions, respectively FXS and AD. Although these pathologies are characterized by different features, they have been reported to share a number of common molecular and cellular players. The aim of this review is to describe the double-edged sword of FMRP in autism and AD, possibly allowing the elucidation of key shared underlying mechanisms and neuronal circuits. As an RBP, FMRP is able to regulate APP expression promoting the production of amyloid β fragments. Indeed, FXS patients show an increase of amyloid β load, typical of other neurological disorders, such as AD, Down syndrome, Parkinson’s Disease, etc. Beyond APP dysmetabolism, the two neurodegenerative conditions share molecular targets, brain circuits and related cognitive deficits. In this review, we will point out the potential common neuropathological pattern which needs to be addressed and we will hopefully contribute to clarifying the complex phenotype of these two neurorological disorders, in order to pave the way for a novel, common disease-modifying therapy.
Collapse
Affiliation(s)
- Louis Bleuzé
- University de Rennes 1, Rennes, France.,Humanitas Clinical and Research Center-IRCCS, Rozzano (Mi), Italy
| | - Viviana Triaca
- Institute of Biochemistry and Cell Biology, National Research Council (CNR-IBBC), International Campus A. Buzzati Traverso, Monterotondo, Italy
| | - Antonella Borreca
- Humanitas Clinical and Research Center-IRCCS, Rozzano (Mi), Italy.,Institute of Neuroscience-National Research Council (CNR-IN), Milan, Italy
| |
Collapse
|
16
|
Romagnoli A, Di Marino D. The Use of Peptides in the Treatment of Fragile X Syndrome: Challenges and Opportunities. Front Psychiatry 2021; 12:754485. [PMID: 34803767 PMCID: PMC8599826 DOI: 10.3389/fpsyt.2021.754485] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/11/2021] [Indexed: 01/17/2023] Open
Abstract
Fragile X Syndrome (FXS) is the most frequent cause of inherited intellectual disabilities and autism spectrum disorders, characterized by cognitive deficits and autistic behaviors. The silencing of the Fmr1 gene and consequent lack of FMRP protein, is the major contribution to FXS pathophysiology. FMRP is an RNA binding protein involved in the maturation and plasticity of synapses and its absence culminates in a range of morphological, synaptic and behavioral phenotypes. Currently, there are no approved medications for the treatment of FXS, with the approaches under study being fairly specific and unsatisfying in human trials. Here we propose peptides/peptidomimetics as candidates in the pharmacotherapy of FXS; in the last years this class of molecules has catalyzed the attention of pharmaceutical research, being highly selective and well-tolerated. Thanks to their ability to target protein-protein interactions (PPIs), they are already being tested for a wide range of diseases, including cancer, diabetes, inflammation, Alzheimer's disease, but this approach has never been applied to FXS. As FXS is at the forefront of efforts to develop new drugs and approaches, we discuss opportunities, challenges and potential issues of peptides/peptidomimetics in FXS drug design and development.
Collapse
Affiliation(s)
| | - Daniele Di Marino
- Department of Life and Environmental Sciences, New York-Marche Structural Biology Center (NY-MaSBiC), Polytechnic University of Marche, Ancona, Italy
| |
Collapse
|
17
|
Beyond Trinucleotide Repeat Expansion in Fragile X Syndrome: Rare Coding and Noncoding Variants in FMR1 and Associated Phenotypes. Genes (Basel) 2021; 12:genes12111669. [PMID: 34828275 PMCID: PMC8623550 DOI: 10.3390/genes12111669] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 11/17/2022] Open
Abstract
FMR1 (FMRP translational regulator 1) variants other than repeat expansion are known to cause disease phenotypes but can be overlooked if they are not accounted for in genetic testing strategies. We collected and reanalyzed the evidence for pathogenicity of FMR1 coding, noncoding, and copy number variants published to date. There is a spectrum of disease-causing FMR1 variation, with clinical and functional evidence supporting pathogenicity of five splicing, five missense, one in-frame deletion, one nonsense, and four frameshift variants. In addition, FMR1 deletions occur in both mosaic full mutation patients and as constitutional pathogenic alleles. De novo deletions arise not only from full mutation alleles but also alleles with normal-sized CGG repeats in several patients, suggesting that the CGG repeat region may be prone to genomic instability even in the absence of repeat expansion. We conclude that clinical tests for potentially FMR1-related indications such as intellectual disability should include methods capable of detecting small coding, noncoding, and copy number variants.
Collapse
|
18
|
Grosso V, Marcolungo L, Maestri S, Alfano M, Lavezzari D, Iadarola B, Salviati A, Mariotti B, Botta A, D’Apice MR, Novelli G, Delledonne M, Rossato M. Characterization of FMR1 Repeat Expansion and Intragenic Variants by Indirect Sequence Capture. Front Genet 2021; 12:743230. [PMID: 34646309 PMCID: PMC8504923 DOI: 10.3389/fgene.2021.743230] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022] Open
Abstract
Traditional methods for the analysis of repeat expansions, which underlie genetic disorders, such as fragile X syndrome (FXS), lack single-nucleotide resolution in repeat analysis and the ability to characterize causative variants outside the repeat array. These drawbacks can be overcome by long-read and short-read sequencing, respectively. However, the routine application of next-generation sequencing in the clinic requires target enrichment, and none of the available methods allows parallel analysis of long-DNA fragments using both sequencing technologies. In this study, we investigated the use of indirect sequence capture (Xdrop technology) coupled to Nanopore and Illumina sequencing to characterize FMR1, the gene responsible of FXS. We achieved the efficient enrichment (> 200×) of large target DNA fragments (~60-80 kbp) encompassing the entire FMR1 gene. The analysis of Xdrop-enriched samples by Nanopore long-read sequencing allowed the complete characterization of repeat lengths in samples with normal, pre-mutation, and full mutation status (> 1 kbp), and correctly identified repeat interruptions relevant for disease prognosis and transmission. Single-nucleotide variants (SNVs) and small insertions/deletions (indels) could be detected in the same samples by Illumina short-read sequencing, completing the mutational testing through the identification of pathogenic variants within the FMR1 gene, when no typical CGG repeat expansion is detected. The study successfully demonstrated the parallel analysis of repeat expansions and SNVs/indels in the FMR1 gene at single-nucleotide resolution by combining Xdrop enrichment with two next-generation sequencing approaches. With the appropriate optimization necessary for the clinical settings, the system could facilitate both the study of genotype-phenotype correlation in FXS and enable a more efficient diagnosis and genetic counseling for patients and their relatives.
Collapse
Affiliation(s)
- Valentina Grosso
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Luca Marcolungo
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Simone Maestri
- Department of Biotechnology, University of Verona, Verona, Italy
| | | | - Denise Lavezzari
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Barbara Iadarola
- Department of Biotechnology, University of Verona, Verona, Italy
| | - Alessandro Salviati
- Department of Biotechnology, University of Verona, Verona, Italy
- GENARTIS srl, Verona, Italy
| | - Barbara Mariotti
- Department of Medicine, Section of General Pathology, University of Verona, Verona, Italy
| | - Annalisa Botta
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome "Tor Vergata", Rome, Italy
| | | | - Giuseppe Novelli
- Department of Biomedicine and Prevention, Medical Genetics Section, University of Rome "Tor Vergata", Rome, Italy
- IRCCS Neuromed Mediterranean Neurological Institute, Pozzilli, Italy
- Department of Pharmacology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Massimo Delledonne
- Department of Biotechnology, University of Verona, Verona, Italy
- GENARTIS srl, Verona, Italy
| | - Marzia Rossato
- Department of Biotechnology, University of Verona, Verona, Italy
- GENARTIS srl, Verona, Italy
| |
Collapse
|
19
|
Adayev T, LaFauci G, Xu W, Dobkin C, Kascsak R, Brown WT, Goodman JH. Development of a Quantitative FMRP Assay for Mouse Tissue Applications. Genes (Basel) 2021; 12:genes12101516. [PMID: 34680911 PMCID: PMC8535242 DOI: 10.3390/genes12101516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 11/20/2022] Open
Abstract
Fragile X syndrome results from the absence of the FMR1 gene product—Fragile X Mental Retardation Protein (FMRP). Fragile X animal research has lacked a reliable method to quantify FMRP. We report the development of an array of FMRP-specific monoclonal antibodies and their application for quantitative assessment of FMRP (qFMRPm) in mouse tissue. To characterize the assay, we determined the normal variability of FMRP expression in four brain structures of six different mouse strains at seven weeks of age. There was a hierarchy of FMRP expression: neocortex > hippocampus > cerebellum > brainstem. The expression of FMRP was highest and least variable in the neocortex, whereas it was most variable in the hippocampus. Male C57Bl/6J and FVB mice were selected to determine FMRP developmental differences in the brain at 3, 7, 10, and 14 weeks of age. We examined the four structures and found a developmental decline in FMRP expression with age, except for the brainstem where it remained stable. qFMRPm assay of blood had highest values in 3 week old animals and dropped by 2.5-fold with age. Sex differences were not significant. The results establish qFMRPm as a valuable tool due to its ease of methodology, cost effectiveness, and accuracy.
Collapse
Affiliation(s)
- Tatyana Adayev
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
- Correspondence: ; Tel.: +1-718-494-5314
| | - Giuseppe LaFauci
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
| | - Weimin Xu
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
| | - Carl Dobkin
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
| | - Richard Kascsak
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
| | - W. Ted Brown
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
- Perkins Center, University of Sydney Camperdown, Sydney, NSW 2006, Australia
| | - Jeffrey H. Goodman
- New York State Institute for Basic Research in Developmental Disabilities, New York, NY 10314, USA; (G.L.); (W.X.); (C.D.); (R.K.); (W.T.B.); (J.H.G.)
| |
Collapse
|
20
|
Mary L, Nourisson E, Feger C, Laugel V, Chaigne D, Keren B, Afenjar A, Billette T, Trost D, Cieuta-Walti C, Gerard B, Piton A, Schaefer E. Pathogenic variants in KCNQ2 cause intellectual deficiency without epilepsy: Broadening the phenotypic spectrum of a potassium channelopathy. Am J Med Genet A 2021; 185:1803-1815. [PMID: 33754465 DOI: 10.1002/ajmg.a.62181] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/19/2021] [Accepted: 03/11/2021] [Indexed: 12/22/2022]
Abstract
High-throughput sequencing (HTS) improved the molecular diagnosis in individuals with intellectual deficiency (ID) and helped to broaden the phenotype of previously known disease-causing genes. We report herein four unrelated patients with isolated ID, carriers of a likely pathogenic variant in KCNQ2, a gene usually implicated in benign familial neonatal seizures (BFNS) or early onset epileptic encephalopathy (EOEE). Patients were diagnosed by targeted HTS or exome sequencing. Pathogenicity of the variants was assessed by multiple in silico tools. Patients' ID ranged from mild to severe with predominance of speech disturbance and autistic features. Three of the four variants disrupted the same amino acid. Compiling all the pathogenic variants previously reported, we observed a strong overlap between variants causing EOEE, isolated ID, and BFNS and an important intra-familial phenotypic variability, although missense variants in the voltage-sensing domain and the pore are significantly associated to EOEE (p < 0.01, Fisher test). Thus, pathogenic variants in KCNQ2 can be associated with isolated ID. We did not highlight strong related genotype-phenotype correlations in KCNQ2-related disorders. A second genetic hit, a burden of rare variants, or other extrinsic factors may explain such a phenotypic variability. However, it is of interest to study encephalopathy genes in non-epileptic ID patients.
Collapse
Affiliation(s)
- Laura Mary
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Elsa Nourisson
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Claire Feger
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Vincent Laugel
- Service de Neuropédiatrie, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Denys Chaigne
- Service de Neuropédiatrie, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Boris Keren
- Département de Génétique, Centre de Référence des Déficiences Intellectuelles de Causes Rares, Groupe de Recherche Clinique "Déficiences Intellectuelles et Autisme," Université Pierre et Marie Curie, Hôpital de la Pitié-Salpêtrière, Paris, France.,Institut du Cerveau et de la Moelle Épinière, Sorbonne Universités, Université Pierre et Marie Curie (Université Paris 06), UMRS 1127, INSERM U 1127, CNRS UMR 7225, Paris, France
| | - Alexandra Afenjar
- Centre de Référence Déficiences Intellectuelles de Causes Rares, Département de Génétique et Embryologie Médicale, Hôpital Trousseau, Sorbonne Universités, Paris, France
| | - Thierry Billette
- Assistance Publique-Hôpitaux de Paris, Service de Neuropédiatrie, Hôpital Armand Trousseau, Paris, France
| | | | | | - Bénédicte Gerard
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Amélie Piton
- Laboratoire de Diagnostic Génétique, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.,Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), CNRS UMR-7104, Inserm U964, Université de Strasbourg, Strasbourg, France
| | - Elise Schaefer
- Service de Génétique Médicale, Hôpitaux Universitaires de Strasbourg, Institut de Génétique Médicale d'Alsace, Strasbourg, France
| |
Collapse
|
21
|
Okazaki T, Adachi K, Matsuura K, Oyama Y, Nose M, Shirahata E, Abe T, Hasegawa T, Maihara T, Maegaki Y, Nanba E. Clinical Characteristics of Fragile X Syndrome Patients in Japan. Yonago Acta Med 2021; 64:30-33. [PMID: 33642901 DOI: 10.33160/yam.2021.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/07/2020] [Indexed: 11/05/2022]
Abstract
Background Fragile X syndrome (FXS) is a well-known X-linked disorder clinically characterized by intellectual disability and autistic features. However, diagnosed Japanese FXS cases have been fewer than expected, and clinical features of Japanese FXS patients remain unknown. Methods We evaluated the clinical features of Japanese FXS patients using the results of a questionnaire-based survey. Results We presented the characteristics of seven patients aged 6 to 20 years. Long face and large ears were observed in five of seven patients. Macrocephaly was observed in four of five patients. The meaningful word was first seen at a certain time point between 18 and 72 months (median = 60 months). Developmental quotient or intellectual quotient ranged between 20 and 48 (median = 29). Behavioral disorders were seen in all patients (autistic spectrum disorder in six patients, hyperactivity in five patients). Five patients were diagnosed by polymerase chain reaction analysis, and two patients were diagnosed by the cytogenetic study. All physicians ordered FXS genetic testing for suspicious cases because of clinical manifestations. Conclusion In the present study, a long face, large ears, macrocephaly, autistic spectrum disorder, and hyperactivity were observed in almost cases, and these characteristics might be common features in Japanese FXS patients. Our finding indicated the importance of clinical manifestations to diagnosis FXS. However, the sample size of the present study is small, and these features are also seen to patients with other disorders. We consider that genetic testing for FXS should be performed on a wider range of intellectually disabled cases.
Collapse
Affiliation(s)
- Tetsuya Okazaki
- Division of Clinical Genetics, Tottori University Hospital, Yonago 680-8504, Japan
| | - Kaori Adachi
- Research Initiative Center, Organization for Research Initiative and Promotion, Tottori University, Yonago 680-8503, Japan
| | - Kaori Matsuura
- Division of Clinical Genetics, Tottori University Hospital, Yonago 680-8504, Japan
| | - Yoshitaka Oyama
- Department of Pediatrics, Yokohama City University Medical Center, Yokohama 232-0024, Japan
| | - Madoka Nose
- Department of Pediatrics, Nose Pediatric Clinic, Kobe 653-0004, Japan
| | - Emi Shirahata
- Department of Pediatrics, Yamagata Prefectural Rehabilitation Center for Children with Disabilities, Kaminoyama 990-8570, Japan
| | - Toshiaki Abe
- Department of Pediatrics, Ashikaganomori Hospital, Ashikaga 326-0011, Japan
| | - Takeshi Hasegawa
- Department of Pediatrics, Soka Municipal Hospital, Soka 340-0043, Japan
| | - Toshiro Maihara
- Department of Pediatrics, Hyogo Prefectural Amagasaki General Medical Center, Amagasaki 660-8550, Japan
| | - Yoshihiro Maegaki
- Division of Clinical Genetics, Tottori University Hospital, Yonago 680-8504, Japan.,Division of Child Neurology, Department of Brain and Neurosciences, Faculty of Medicine, Tottori University, Yonago 680-8504, Japan
| | - Eiji Nanba
- Division of Clinical Genetics, Tottori University Hospital, Yonago 680-8504, Japan.,Research Strategy Division, Organization for Research Initiative and Promotion, Tottori University, Yonago 680-8503, Japan
| |
Collapse
|
22
|
Zeidler S, Severijnen LA, de Boer H, van der Toorn EC, Ruivenkamp CAL, Bijlsma EK, Willemsen R. A missense variant in the nuclear export signal of the FMR1 gene causes intellectual disability. Gene 2020; 768:145298. [PMID: 33181255 DOI: 10.1016/j.gene.2020.145298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 10/14/2020] [Accepted: 11/04/2020] [Indexed: 11/15/2022]
Abstract
Fragile X syndrome (FXS) is the most common monogenetic cause of intellectual disability and autism spectrum disorders. Mostly, FXS is caused by transcriptional silencing of the FMR1 gene due to a repeat expansion in the 5' UTR, and consequently lack of the protein product FMRP. However, in rare cases FXS is caused by other types of variants in the FMR1 gene. We describe a missense variant in the FMR1 gene, identified through whole-exome sequencing, in a boy with intellectual disability and behavioral problems. The variant is located in the FMRP's nuclear export signal (NES). We performed expression and localization studies of the variant in hair roots and HEK293 cells. Our results show normal expression but significant retention of the FMRP in the cells' nucleus. This finding suggests a possible FMRP reduction at its essential functional sites in the dendrites and the synaptic compartments and possible interference of other cellular processes in the nucleus. Together, this might lead to a FXS phenotype in the boy.
Collapse
Affiliation(s)
- Shimriet Zeidler
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
| | | | - Helen de Boer
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| | | | - Claudia A L Ruivenkamp
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Emilia K Bijlsma
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands
| |
Collapse
|
23
|
Majumder M, Johnson RH, Palanisamy V. Fragile X-related protein family: a double-edged sword in neurodevelopmental disorders and cancer. Crit Rev Biochem Mol Biol 2020; 55:409-424. [PMID: 32878499 DOI: 10.1080/10409238.2020.1810621] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The fragile X-related (FXR) family proteins FMRP, FXR1, and FXR2 are RNA binding proteins that play a critical role in RNA metabolism, neuronal plasticity, and muscle development. These proteins share significant homology in their protein domains, which are functionally and structurally similar to each other. FXR family members are known to play an essential role in causing fragile X mental retardation syndrome (FXS), the most common genetic form of autism spectrum disorder. Recent advances in our understanding of this family of proteins have occurred in tandem with discoveries of great importance to neurological disorders and cancer biology via the identification of their novel RNA and protein targets. Herein, we review the FXR family of proteins as they pertain to FXS, other mental illnesses, and cancer. We emphasize recent findings and analyses that suggest contrasting functions of this protein family in FXS and tumorigenesis based on their expression patterns in human tissues. Finally, we discuss current gaps in our knowledge regarding the FXR protein family and their role in FXS and cancer and suggest future studies to facilitate bench to bedside translation of the findings.
Collapse
Affiliation(s)
- Mrinmoyee Majumder
- Department of Biochemistry and Molecular Biology, School of Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Roger H Johnson
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, USA
| | - Viswanathan Palanisamy
- Department of Biochemistry and Molecular Biology, School of Medicine, Medical University of South Carolina, Charleston, SC, USA
| |
Collapse
|
24
|
Abstract
RNA-binding proteins are a critical group of multifunctional proteins that precisely regulate all aspects of gene expression, from alternative splicing to mRNA trafficking, stability, and translation. Converging evidence highlights aberrant RNA metabolism as a common pathogenic mechanism in several neurodevelopmental and neurodegenerative diseases. However, dysregulation of disease-linked RNA-binding proteins results in widespread, often tissue-specific and/or pleiotropic effects on the transcriptome, making it challenging to determine the underlying cellular and molecular mechanisms that contribute to disease pathogenesis. Understanding how splicing misregulation as well as alterations of mRNA stability and localization impact the activity and function of neuronal proteins is fundamental to addressing neurodevelopmental defects and synaptic dysfunction in disease. Here we highlight recent exciting studies that use high-throughput transcriptomic analysis and advanced genetic, cell biological, and imaging approaches to dissect the role of disease-linked RNA-binding proteins on different RNA processing steps. We focus specifically on efforts to elucidate the functional consequences of aberrant RNA processing on neuronal morphology, synaptic activity and plasticity in development and disease. We also consider new areas of investigation that will elucidate the molecular mechanisms RNA-binding proteins use to achieve spatiotemporal control of gene expression for neuronal homeostasis and plasticity.
Collapse
Affiliation(s)
- Shavanie Prashad
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA
| | - Pallavi P Gopal
- Department of Pathology, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Experimental Pathology Graduate Group, Yale University School of Medicine, Yale University, New Haven, CT, USA.,Yale Center for RNA Science and Medicine, Yale University School of Medicine, Yale University, New Haven, CT, USA
| |
Collapse
|
25
|
Folci A, Mirabella F, Fossati M. Ubiquitin and Ubiquitin-Like Proteins in the Critical Equilibrium between Synapse Physiology and Intellectual Disability. eNeuro 2020; 7:ENEURO.0137-20.2020. [PMID: 32719102 PMCID: PMC7544190 DOI: 10.1523/eneuro.0137-20.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/08/2020] [Accepted: 06/17/2020] [Indexed: 01/04/2023] Open
Abstract
Posttranslational modifications (PTMs) represent a dynamic regulatory system that precisely modulates the functional organization of synapses. PTMs consist in target modifications by small chemical moieties or conjugation of lipids, sugars or polypeptides. Among them, ubiquitin and a large family of ubiquitin-like proteins (UBLs) share several features such as the structure of the small protein modifiers, the enzymatic cascades mediating the conjugation process, and the targeted aminoacidic residue. In the brain, ubiquitination and two UBLs, namely sumoylation and the recently discovered neddylation orchestrate fundamental processes including synapse formation, maturation and plasticity, and their alteration is thought to contribute to the development of neurological disorders. Remarkably, emerging evidence suggests that these pathways tightly interplay to modulate the function of several proteins that possess pivotal roles for brain homeostasis as well as failure of this crosstalk seems to be implicated in the development of brain pathologies. In this review, we outline the role of ubiquitination, sumoylation, neddylation, and their functional interplay in synapse physiology and discuss their implication in the molecular pathogenesis of intellectual disability (ID), a neurodevelopmental disorder that is frequently comorbid with a wide spectrum of brain pathologies. Finally, we propose a few outlooks that might contribute to better understand the complexity of these regulatory systems in regard to neuronal circuit pathophysiology.
Collapse
Affiliation(s)
- Alessandra Folci
- Humanitas Clinical and Research Center-IRCCS, via Manzoni 56, 20089, Rozzano (MI), Italy
| | - Filippo Mirabella
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20090 Pieve 9 Emanuele - Milan, Italy
| | - Matteo Fossati
- Humanitas Clinical and Research Center-IRCCS, via Manzoni 56, 20089, Rozzano (MI), Italy
- CNR-Institute of Neuroscience, via Manzoni 56, 20089, Rozzano (MI), Italy
| |
Collapse
|
26
|
Prieto M, Folci A, Martin S. Post-translational modifications of the Fragile X Mental Retardation Protein in neuronal function and dysfunction. Mol Psychiatry 2020; 25:1688-1703. [PMID: 31822816 DOI: 10.1038/s41380-019-0629-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/22/2019] [Accepted: 11/27/2019] [Indexed: 12/17/2022]
Abstract
The Fragile X Mental Retardation Protein (FMRP) is an RNA-binding protein essential to the regulation of local translation at synapses. In the mammalian brain, synapses are constantly formed and eliminated throughout development to achieve functional neuronal networks. At the molecular level, thousands of proteins cooperate to accomplish efficient neuronal communication. Therefore, synaptic protein levels and their functional interactions need to be tightly regulated. FMRP generally acts as a translational repressor of its mRNA targets. FMRP is the target of several post-translational modifications (PTMs) that dynamically regulate its function. Here we provide an overview of the PTMs controlling the FMRP function and discuss how their spatiotemporal interplay contributes to the physiological regulation of FMRP. Importantly, FMRP loss-of-function leads to Fragile X syndrome (FXS), a rare genetic developmental condition causing a range of neurological alterations including intellectual disability (ID), learning and memory impairments, autistic-like features and seizures. Here, we also explore the possibility that recently reported missense mutations in the FMR1 gene disrupt the PTM homoeostasis of FMRP, thus participating in the aetiology of FXS. This suggests that the pharmacological targeting of PTMs may be a promising strategy to develop innovative therapies for patients carrying such missense mutations.
Collapse
Affiliation(s)
- Marta Prieto
- Université Côte d'Azur, CNRS, IPMC, Valbonne, France
| | | | - Stéphane Martin
- Université Côte d'Azur, INSERM, CNRS, IPMC, Valbonne, France.
| |
Collapse
|
27
|
Two novel intragenic variants in the FMR1 gene in patients with suspect clinical diagnosis of Fragile X syndrome and no CGG repeat expansion. Eur J Med Genet 2020; 63:104010. [PMID: 32688058 DOI: 10.1016/j.ejmg.2020.104010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/14/2020] [Accepted: 07/15/2020] [Indexed: 12/30/2022]
Abstract
The major and most well-studied genetic cause of Fragile-X syndrome (FXS) is expansion of a CGG repeat in the 5'-UTR of the FMR1 gene. Routine testing for this expansion is performed globally. Overall, there is a paucity of intragenic variants explaining FXS, a fact which is being addressed by a more systematic application of whole exome (WES) and whole genome (WGS) sequencing, even in the diagnostic setting. Here we report two families comprising probands with a clinical suspicion of FXS and no CGG repeat expansions. Using WES/WGS we identified deleterious variants within the coding region of FMR1 in both families. In a family from Finland we identified a complex indel c.1021-1028delinsTATTGG in exon 11 of FMR1 which gives rise to a frameshift and a premature termination codon (PTC), p.Asn341Tyrfs*7. Follow-up mRNA and protein studies on a cell line from the proband revealed that although the mRNA levels of FMR1 were not altered, Fragile X Mental Retardation 1 Protein (FMRP) was undetectable. Additionally, we identified a variant, c.881-1G > T, affecting the canonical acceptor splice site of exon 10 of FMR1 in an Australian family. Our findings reinforce the importance of intragenic FMR1 variant testing, particularly in cases with clinical features of FXS and no CGG repeat expansions identified.
Collapse
|
28
|
Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS): Pathophysiology and Clinical Implications. Int J Mol Sci 2020; 21:ijms21124391. [PMID: 32575683 PMCID: PMC7352421 DOI: 10.3390/ijms21124391] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/23/2020] [Accepted: 05/28/2020] [Indexed: 02/06/2023] Open
Abstract
The fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder seen in older premutation (55-200 CGG repeats) carriers of FMR1. The premutation has excessive levels of FMR1 mRNA that lead to toxicity and mitochondrial dysfunction. The clinical features usually begin in the 60 s with an action or intention tremor followed by cerebellar ataxia, although 20% have only ataxia. MRI features include brain atrophy and white matter disease, especially in the middle cerebellar peduncles, periventricular areas, and splenium of the corpus callosum. Neurocognitive problems include memory and executive function deficits, although 50% of males can develop dementia. Females can be less affected by FXTAS because of a second X chromosome that does not carry the premutation. Approximately 40% of males and 16% of female carriers develop FXTAS. Since the premutation can occur in less than 1 in 200 women and 1 in 400 men, the FXTAS diagnosis should be considered in patients that present with tremor, ataxia, parkinsonian symptoms, neuropathy, and psychiatric problems. If a family history of a fragile X mutation is known, then FMR1 DNA testing is essential in patients with these symptoms.
Collapse
|
29
|
Golden CEM, Breen MS, Koro L, Sonar S, Niblo K, Browne A, Burlant N, Di Marino D, De Rubeis S, Baxter MG, Buxbaum JD, Harony-Nicolas H. Deletion of the KH1 Domain of Fmr1 Leads to Transcriptional Alterations and Attentional Deficits in Rats. Cereb Cortex 2020; 29:2228-2244. [PMID: 30877790 PMCID: PMC6458915 DOI: 10.1093/cercor/bhz029] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 12/11/2018] [Accepted: 02/06/2019] [Indexed: 12/27/2022] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder caused by mutations in the FMR1 gene. It is a leading monogenic cause of autism spectrum disorder and inherited intellectual disability and is often comorbid with attention deficits. Most FXS cases are due to an expansion of CGG repeats leading to suppressed expression of fragile X mental retardation protein (FMRP), an RNA-binding protein involved in mRNA metabolism. We found that the previously published Fmr1 knockout rat model of FXS expresses an Fmr1 transcript with an in-frame deletion of exon 8, which encodes for the K-homology (KH) RNA-binding domain, KH1. Notably, 3 pathogenic missense mutations associated with FXS lie in the KH domains. We observed that the deletion of exon 8 in rats leads to attention deficits and to alterations in transcriptional profiles within the medial prefrontal cortex (mPFC), which map to 2 weighted gene coexpression network modules. These modules are conserved in human frontal cortex and enriched for known FMRP targets. Hub genes in these modules represent potential therapeutic targets for FXS. Taken together, these findings indicate that attentional testing might be a reliable cross-species tool for investigating FXS and identify dysregulated conserved gene networks in a relevant brain region.
Collapse
Affiliation(s)
- Carla E M Golden
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michael S Breen
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lacin Koro
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sankalp Sonar
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kristi Niblo
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Andrew Browne
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Natalie Burlant
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Daniele Di Marino
- Faculty of Biomedical Sciences, Institute of Computational Science, Center for Computational Medicine in Cardiology, Università della Svizzera Italiana (USI), Lugano, Switzerland.,Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Silvia De Rubeis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mark G Baxter
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Joseph D Buxbaum
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Hala Harony-Nicolas
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| |
Collapse
|
30
|
Loss of the KH1 domain of FMR1 in humans due to a synonymous variant causes global developmental retardation. Gene 2020; 753:144793. [PMID: 32446918 DOI: 10.1016/j.gene.2020.144793] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/30/2020] [Accepted: 05/18/2020] [Indexed: 11/20/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) is a monogenic disorder and a common cause of intellectual disability (ID). Up to now, very few pathological variants other than the typical CGG-repeat expansion have been reported in the FMR1 gene. METHODS A panel of 56 intellectual disability (ID) genes including the FMR1 gene was sequenced in a cohort of 300 patients with unexplained ID. To determine the effect of a new FMR1 variant, total RNA from peripheral blood cells was reverse transcribed, amplified by polymerase chain reaction and sequenced. RESULTS We report a novel G to A point variant (c.801G > A) located at the last nucleotide of exon 8 in the FMR1 gene in one patient with ID. Direct sequencing of the RT-PCR products revealed that the transcript from the allele with G to A variant skips exon 8 entirely, resulting in a joining of exons 7 and 9. Skipping of exon 8 may result in an abnormal FMR1 protein (FMRP), which removes the highly conserved region that encoding the KH1 domain of FMRP. CONCLUSIONS This report describes for the first time that a synonymous variant in the FMR1 gene is associated with an error in mRNA processing, leading preferentially to the production of an aberrant transcript without exon 8. This splice variant was associated with an unspecific clinical presentation, suggesting the need for more detailed investigation of silent variants in ID patients with a large spectrum of phenotypes.
Collapse
|
31
|
La Rosa P, Petrillo S, Bertini ES, Piemonte F. Oxidative Stress in DNA Repeat Expansion Disorders: A Focus on NRF2 Signaling Involvement. Biomolecules 2020; 10:biom10050702. [PMID: 32369911 PMCID: PMC7277112 DOI: 10.3390/biom10050702] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/13/2022] Open
Abstract
DNA repeat expansion disorders are a group of neuromuscular and neurodegenerative diseases that arise from the inheritance of long tracts of nucleotide repetitions, located in the regulatory region, introns, or inside the coding sequence of a gene. Although loss of protein expression and/or the gain of function of its transcribed mRNA or translated product represent the major pathogenic effect of these pathologies, mitochondrial dysfunction and imbalance in redox homeostasis are reported as common features in these disorders, deeply affecting their severity and progression. In this review, we examine the role that the redox imbalance plays in the pathological mechanisms of DNA expansion disorders and the recent advances on antioxidant treatments, particularly focusing on the expression and the activity of the transcription factor NRF2, the main cellular regulator of the antioxidant response.
Collapse
|
32
|
Salcedo-Arellano MJ, Dufour B, McLennan Y, Martinez-Cerdeno V, Hagerman R. Fragile X syndrome and associated disorders: Clinical aspects and pathology. Neurobiol Dis 2020; 136:104740. [PMID: 31927143 PMCID: PMC7027994 DOI: 10.1016/j.nbd.2020.104740] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/17/2019] [Accepted: 01/08/2020] [Indexed: 12/23/2022] Open
Abstract
This review aims to assemble many years of research and clinical experience in the fields of neurodevelopment and neuroscience to present an up-to-date understanding of the clinical presentation, molecular and brain pathology associated with Fragile X syndrome, a neurodevelopmental condition that develops with the full mutation of the FMR1 gene, located in the q27.3 loci of the X chromosome, and Fragile X-associated tremor/ataxia syndrome a neurodegenerative disease experienced by aging premutation carriers of the FMR1 gene. It is important to understand that these two syndromes have a very distinct clinical and pathological presentation while sharing the same origin: the mutation of the FMR1 gene; revealing the complexity of expansion genetics.
Collapse
Affiliation(s)
- Maria Jimena Salcedo-Arellano
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, USA; Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA, USA; Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA, USA.
| | - Brett Dufour
- Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA, USA; Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA, USA
| | - Yingratana McLennan
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, USA; Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA, USA
| | - Veronica Martinez-Cerdeno
- Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA, USA; Institute for Pediatric Regenerative Medicine and Shriners Hospitals for Children Northern California, Sacramento, CA, USA; Department of Pathology and Laboratory Medicine, UC Davis School of Medicine, Sacramento, CA, USA
| | - Randi Hagerman
- Department of Pediatrics, University of California Davis School of Medicine, Sacramento, CA, USA; Medical Investigation of Neurodevelopmental Disorders (MIND) Institute, University of California Davis, Sacramento, CA, USA.
| |
Collapse
|
33
|
Sawicka K, Hale CR, Park CY, Fak JJ, Gresack JE, Van Driesche SJ, Kang JJ, Darnell JC, Darnell RB. FMRP has a cell-type-specific role in CA1 pyramidal neurons to regulate autism-related transcripts and circadian memory. eLife 2019; 8:e46919. [PMID: 31860442 PMCID: PMC6924960 DOI: 10.7554/elife.46919] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 12/02/2019] [Indexed: 12/14/2022] Open
Abstract
Loss of the RNA binding protein FMRP causes Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability, yet it is unknown how FMRP function varies across brain regions and cell types and how this contributes to disease pathophysiology. Here we use conditional tagging of FMRP and CLIP (FMRP cTag CLIP) to examine FMRP mRNA targets in hippocampal CA1 pyramidal neurons, a critical cell type for learning and memory relevant to FXS phenotypes. Integrating these data with analysis of ribosome-bound transcripts in these neurons revealed CA1-enriched binding of autism-relevant mRNAs, and CA1-specific regulation of transcripts encoding circadian proteins. This contrasted with different targets in cerebellar granule neurons, and was consistent with circadian defects in hippocampus-dependent memory in Fmr1 knockout mice. These findings demonstrate differential FMRP-dependent regulation of mRNAs across neuronal cell types that may contribute to phenotypes such as memory defects and sleep disturbance associated with FXS.
Collapse
Affiliation(s)
- Kirsty Sawicka
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Caryn R Hale
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Christopher Y Park
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - John J Fak
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Jodi E Gresack
- Laboratory of Molecular and Cellular NeuroscienceThe Rockefeller UniversityNew YorkUnited States
| | - Sarah J Van Driesche
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Jin Joo Kang
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Jennifer C Darnell
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
| | - Robert B Darnell
- Laboratory of Molecular Neuro-OncologyThe Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical InstituteChevy ChaseUnited States
| |
Collapse
|
34
|
Hensel CH, Vanzo RJ, Martin MM, Ling L, Aliaga SM, Bui M, Francis DI, Twede H, Field MH, Morison JW, Amor DJ, Godler DE. Abnormally Methylated FMR1 in Absence of a Detectable Full Mutation in a U.S.A Patient Cohort Referred for Fragile X Testing. Sci Rep 2019; 9:15315. [PMID: 31653898 PMCID: PMC6814816 DOI: 10.1038/s41598-019-51618-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 09/30/2019] [Indexed: 12/11/2022] Open
Abstract
In 2016, Methylation-Specific Quantitative Melt Analysis (MS-QMA) on 3,340 male probands increased diagnostic yield from 1.60% to 1.84% for fragile X syndrome (FXS) using a pooling approach. In this study probands from Lineagen (UT, U.S.A.) of both sexes were screened using MS-QMA without sample pooling. The cohorts included: (i) 279 probands with no FXS full mutation (FM: CGG > 200) detected by AmplideX CGG sizing; (ii) 374 negative and 47 positive controls. MS-QMA sensitivity and specificity in controls approached 100% for both sexes. For male probands with no FM detected by standard testing (n = 189), MS-QMA identified abnormal DNA methylation (mDNA) in 4% normal size (NS: < 44 CGGs), 6% grey zone (CGG 45–54) and 12% premutation (CGG 54–199) alleles. The abnormal mDNA was confirmed by AmplideX methylation sensitive (m)PCR and EpiTYPER tests. In contrast, no abnormal mDNA was detected in 89 males with NS alleles from the general population. For females, 11% of 43 probands with NS alleles by the AmplideX sizing assay had abnormal mDNA by MS-QMA, with FM / NS mosaicism confirmed by AmplideX mPCR. FMR1 MS-QMA analysis can cost-effectively screen probands of both sexes for methylation and FM mosaicism that may be missed by standard testing.
Collapse
Affiliation(s)
| | - Rena J Vanzo
- Lineagen, Inc., Salt Lake City, UT, United States of America
| | - Megan M Martin
- Lineagen, Inc., Salt Lake City, UT, United States of America
| | - Ling Ling
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
| | - Solange M Aliaga
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
| | - Minh Bui
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia
| | - David I Francis
- Victorian Clinical Genetics Services and Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
| | - Hope Twede
- Lineagen, Inc., Salt Lake City, UT, United States of America
| | - Michael H Field
- Genetics of Learning Disability Service (GOLD service), Hunter Genetics, Newcastle, NSW, Australia
| | - Jonathon W Morison
- Business Development and Legal Office, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
| | - David J Amor
- Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.,Neurodisability and Rehabilitation Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia
| | - David E Godler
- Diagnosis and Development, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, VIC, Australia. .,Faculty of Medicine, Dentistry and Health Sciences, Department of Paediatrics, University of Melbourne, Parkville, VIC, Australia.
| |
Collapse
|
35
|
Maddirevula S, Alsaif HS, Ibrahim N, Alkuraya FS. A de novo mutation in FMR1 in a patient with intellectual disability. Eur J Med Genet 2019; 63:103763. [PMID: 31518692 DOI: 10.1016/j.ejmg.2019.103763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 09/09/2019] [Indexed: 10/26/2022]
Affiliation(s)
- Sateesh Maddirevula
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hessa S Alsaif
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia; Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
| |
Collapse
|
36
|
Specchia V, Puricella A, D'Attis S, Massari S, Giangrande A, Bozzetti MP. Drosophila melanogaster as a Model to Study the Multiple Phenotypes, Related to Genome Stability of the Fragile-X Syndrome. Front Genet 2019; 10:10. [PMID: 30815010 PMCID: PMC6381874 DOI: 10.3389/fgene.2019.00010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/11/2019] [Indexed: 12/14/2022] Open
Abstract
Fragile-X syndrome is one of the most common forms of inherited mental retardation and autistic behaviors. The reduction/absence of the functional FMRP protein, coded by the X-linked Fmr1 gene in humans, is responsible for the syndrome. Patients exhibit a variety of symptoms predominantly linked to the function of FMRP protein in the nervous system like autistic behavior and mild-to-severe intellectual disability. Fragile-X (FraX) individuals also display cellular and morphological traits including branched dendritic spines, large ears, and macroorchidism. The dFmr1 gene is the Drosophila ortholog of the human Fmr1 gene. dFmr1 mutant flies exhibit synaptic abnormalities, behavioral defects as well as an altered germline development, resembling the phenotypes observed in FraX patients. Therefore, Drosophila melanogaster is considered a good model to study the physiopathological mechanisms underlying the Fragile-X syndrome. In this review, we explore how the multifaceted roles of the FMRP protein have been addressed in the Drosophila model and how the gained knowledge may open novel perspectives for understanding the molecular defects causing the disease and for identifying novel therapeutical targets.
Collapse
Affiliation(s)
- Valeria Specchia
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, DiSTeBA, Università del Salento, Lecce, Italy
| | - Antonietta Puricella
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, DiSTeBA, Università del Salento, Lecce, Italy
| | - Simona D'Attis
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, DiSTeBA, Università del Salento, Lecce, Italy
| | - Serafina Massari
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, DiSTeBA, Università del Salento, Lecce, Italy
| | - Angela Giangrande
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France.,Centre National de la Recherche Scientifique, UMR7104, Illkirch, France.,Institut National de la Santé et de la Recherche Médicale, U964, Illkirch, France.,Université de Strasbourg, Illkirch, France
| | - Maria Pia Bozzetti
- Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, DiSTeBA, Università del Salento, Lecce, Italy
| |
Collapse
|
37
|
Tzschach A. X-chromosomale Intelligenzminderung. MED GENET-BERLIN 2018. [DOI: 10.1007/s11825-018-0207-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Zusammenfassung
X-chromosomale Intelligenzminderung („X-linked intellectual disability“, XLID) ist eine heterogene Krankheitsgruppe; inzwischen sind mehr als 100 XLID-Gene identifiziert worden. Das Fragile-X-Syndrom mit CGG-Repeatexpansion in der 5’-UTR des FMR1-Gens ist die häufigste monogene Ursache für Intelligenzminderung. Weitere X‑chromosomale Gene mit vergleichsweise hohen Mutationsprävalenzen sind ATRX, RPS6KA3, GPC3, SLC16A2, SLC6A8 und ARX. Die Ursachen für XLID verteilen sich zu ca. 90 % auf molekulargenetisch nachweisbare Mutationen und zu ca. 10 % auf chromosomale Kopienzahlvarianten („copy-number variants“, CNVs). Häufige CNVs sind Duplikationen in Xq28 unter Einschluss von MECP2 sowie das Xp11.22-Duplikations-Syndrom mit Überexpression von HUWE1. Mit den aktuellen Untersuchungsmethoden kann bei ca. 10 % der männlichen Patienten mit Intelligenzminderung eine X‑chromosomale Ursache nachgewiesen werden. Neue Erkenntnisse zu XLID sind für die nächsten Jahre am ehesten in den nicht kodierenden Regionen zu erwarten, wo wahrscheinlich ein weiterer Teil der Ursachen für das bislang nicht vollständig erklärte Überwiegen männlicher Patienten zu suchen ist.
Collapse
Affiliation(s)
- Andreas Tzschach
- Aff1 0000 0001 2111 7257 grid.4488.0 Institut für Klinische Genetik Technische Universität Dresden Fetscherstr. 74 01307 Dresden Deutschland
| |
Collapse
|
38
|
Moine H, Vitale N. Of local translation control and lipid signaling in neurons. Adv Biol Regul 2018; 71:194-205. [PMID: 30262213 DOI: 10.1016/j.jbior.2018.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 09/12/2018] [Accepted: 09/12/2018] [Indexed: 12/12/2022]
Abstract
Fine-tuned regulation of new proteins synthesis is key to the fast adaptation of cells to their changing environment and their response to external cues. Protein synthesis regulation is particularly refined and important in the case of highly polarized cells like neurons where translation occurs in the subcellular dendritic compartment to produce long-lasting changes that enable the formation, strengthening and weakening of inter-neuronal connection, constituting synaptic plasticity. The changes in local synaptic proteome of neurons underlie several aspects of synaptic plasticity and new protein synthesis is necessary for long-term memory formation. Details of how neuronal translation is locally controlled only start to be unraveled. A generally accepted view is that mRNAs are transported in a repressed state and are translated locally upon externally cued triggering signaling cascades that derepress or activate translation machinery at specific sites. Some important yet poorly considered intermediates in these cascades of events are signaling lipids such as diacylglycerol and its balancing partner phosphatidic acid. A link between these signaling lipids and the most common inherited cause of intellectual disability, Fragile X syndrome, is emphasizing the important role of these secondary messages in synaptically controlled translation.
Collapse
Affiliation(s)
- Hervé Moine
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404, Illkirch, France; Centre National de la Recherche Scientifique, UMR7104, 67404, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, 67404, Illkirch, France; Université de Strasbourg, 67084, Strasbourg, France.
| | - Nicolas Vitale
- Université de Strasbourg, 67084, Strasbourg, France; Institut des Neurosciences Cellulaires et Intégratives, UPR3212 CNRS, 67084, Strasbourg, France
| |
Collapse
|
39
|
Dahlhaus R. Of Men and Mice: Modeling the Fragile X Syndrome. Front Mol Neurosci 2018; 11:41. [PMID: 29599705 PMCID: PMC5862809 DOI: 10.3389/fnmol.2018.00041] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/31/2018] [Indexed: 12/26/2022] Open
Abstract
The Fragile X Syndrome (FXS) is one of the most common forms of inherited intellectual disability in all human societies. Caused by the transcriptional silencing of a single gene, the fragile x mental retardation gene FMR1, FXS is characterized by a variety of symptoms, which range from mental disabilities to autism and epilepsy. More than 20 years ago, a first animal model was described, the Fmr1 knock-out mouse. Several other models have been developed since then, including conditional knock-out mice, knock-out rats, a zebrafish and a drosophila model. Using these model systems, various targets for potential pharmaceutical treatments have been identified and many treatments have been shown to be efficient in preclinical studies. However, all attempts to turn these findings into a therapy for patients have failed thus far. In this review, I will discuss underlying difficulties and address potential alternatives for our future research.
Collapse
Affiliation(s)
- Regina Dahlhaus
- Institute for Biochemistry, Emil-Fischer Centre, University of Erlangen-Nürnberg, Erlangen, Germany
| |
Collapse
|
40
|
Khayachi A, Gwizdek C, Poupon G, Alcor D, Chafai M, Cassé F, Maurin T, Prieto M, Folci A, De Graeve F, Castagnola S, Gautier R, Schorova L, Loriol C, Pronot M, Besse F, Brau F, Deval E, Bardoni B, Martin S. Sumoylation regulates FMRP-mediated dendritic spine elimination and maturation. Nat Commun 2018; 9:757. [PMID: 29472612 PMCID: PMC5823917 DOI: 10.1038/s41467-018-03222-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 01/28/2018] [Indexed: 12/02/2022] Open
Abstract
Fragile X syndrome (FXS) is the most frequent inherited cause of intellectual disability and the best-studied monogenic cause of autism. FXS results from the functional absence of the fragile X mental retardation protein (FMRP) leading to abnormal pruning and consequently to synaptic communication defects. Here we show that FMRP is a substrate of the small ubiquitin-like modifier (SUMO) pathway in the brain and identify its active SUMO sites. We unravel the functional consequences of FMRP sumoylation in neurons by combining molecular replacement strategy, biochemical reconstitution assays with advanced live-cell imaging. We first demonstrate that FMRP sumoylation is promoted by activation of metabotropic glutamate receptors. We then show that this increase in sumoylation controls the homomerization of FMRP within dendritic mRNA granules which, in turn, regulates spine elimination and maturation. Altogether, our findings reveal the sumoylation of FMRP as a critical activity-dependent regulatory mechanism of FMRP-mediated neuronal function. Fragile X syndrome patients display intellectual disability and autism, caused by mutations in the RNA-binding protein fragile X mental retardation protein (FMRP). Here, the authors show that FMRP sumoylation is required for regulating spine density and maturation.
Collapse
Affiliation(s)
| | - Carole Gwizdek
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Gwénola Poupon
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Damien Alcor
- Université Côte d'Azur, INSERM, C3M, 06200, Nice, France
| | - Magda Chafai
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Frédéric Cassé
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Thomas Maurin
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Marta Prieto
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | | | | | | | - Romain Gautier
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Lenka Schorova
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Céline Loriol
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Marie Pronot
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Florence Besse
- Université Côte d'Azur, CNRS, INSERM, iBV, 06108, Nice, France
| | - Frédéric Brau
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Emmanuel Deval
- Université Côte d'Azur, CNRS, IPMC, 06560, Valbonne, France
| | - Barbara Bardoni
- Université Côte d'Azur, INSERM, CNRS, IPMC, 06560, Valbonne, France
| | - Stéphane Martin
- Université Côte d'Azur, INSERM, CNRS, IPMC, 06560, Valbonne, France.
| |
Collapse
|
41
|
Rajaratnam A, Shergill J, Salcedo-Arellano M, Saldarriaga W, Duan X, Hagerman R. Fragile X syndrome and fragile X-associated disorders. F1000Res 2017; 6:2112. [PMID: 29259781 PMCID: PMC5728189 DOI: 10.12688/f1000research.11885.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/20/2017] [Indexed: 12/26/2022] Open
Abstract
Fragile X syndrome (FXS) is caused by a full mutation on the
FMR1 gene and a subsequent lack of FMRP, the protein product of
FMR1. FMRP plays a key role in regulating the translation of many proteins involved in maintaining neuronal synaptic connections; its deficiency may result in a range of intellectual disabilities, social deficits, psychiatric problems, and dysmorphic physical features. A range of clinical involvement is also associated with the
FMR1 premutation, including fragile X-associated tremor ataxia syndrome, fragile X-associated primary ovarian insufficiency, psychiatric problems, hypertension, migraines, and autoimmune problems. Over the past few years, there have been a number of advances in our knowledge of FXS and fragile X-associated disorders, and each of these advances offers significant clinical implications. Among these developments are a better understanding of the clinical impact of the phenomenon known as mosaicism, the revelation that various types of mutations can cause FXS, and improvements in treatment for FXS.
Collapse
Affiliation(s)
| | | | | | - Wilmar Saldarriaga
- MIND Institute, UC Davis Health, Sacramento, CA, USA.,Department of Morphology and Obstetrics & Gynecology, Universidad del Valle, School of Medicine, Cali, Valle del Cauca, Colombia
| | - Xianlai Duan
- MIND Institute, UC Davis Health, Sacramento, CA, USA.,Department of Neurology, The Third Hospital of Changsha, Hunan Sheng, China
| | - Randi Hagerman
- MIND Institute, UC Davis Health, Sacramento, CA, USA.,Department of Pediatrics, University of California, Davis, School of Medicine, Sacramento, CA, USA
| |
Collapse
|
42
|
Sitzmann AF, Hagelstrom RT, Tassone F, Hagerman RJ, Butler MG. Rare FMR1 gene mutations causing fragile X syndrome: A review. Am J Med Genet A 2017; 176:11-18. [PMID: 29178241 DOI: 10.1002/ajmg.a.38504] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 09/21/2017] [Accepted: 09/24/2017] [Indexed: 12/16/2022]
Abstract
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability, typically due to CGG-repeat expansions in the FMR1 gene leading to lack of expression. We identified a rare FMR1 gene mutation (c.413G>A), previously reported in a single patient and reviewed the literature for other rare FMR1 mutations. Our patient at 10 years of age presented with the classical findings of FXS including intellectual disability, autism, craniofacial findings, hyperextensibility, fleshy hands, flat feet, unsteady gait, and seizures but without the typical CGG-repeat expansion. He had more features of FXS than the previously reported patient with the same mutation. Twenty individuals reported previously with rare missense or nonsense mutations or other coding disturbances of the FMR1 gene ranged in age from infancy to 50 years; most were verbal with limited speech, had autism and hyperactivity, and all had intellectual disability. Four of the 20 individuals had a mutation within exon 15, three within exon 5, and two within exon 2. The FMR1 missense mutation (c.413G>A) is the same as in a previously reported male where it was shown that there was preservation of the post-synaptic function of the fragile X mental retardation protein (FMRP), the encoded protein of the FMR1 gene was preserved. Both patients with this missense mutation had physical, cognitive, and behavioral features similarly seen in FXS.
Collapse
Affiliation(s)
- Adam F Sitzmann
- Departments of Psychiatry & Behavioral Sciences and Pediatrics, University of Kansas Medical Center, Kansas City, Kansas
| | - Robert T Hagelstrom
- Human Genetics Laboratory, Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California-Davis Medical Center, Sacramento, California.,MIND Institute, University of California-Davis Medical Center, Sacramento, California
| | - Randi J Hagerman
- MIND Institute, University of California-Davis Medical Center, Sacramento, California.,Department of Pediatrics, University of California-Davis Medical Center, Sacramento, California
| | - Merlin G Butler
- Departments of Psychiatry & Behavioral Sciences and Pediatrics, University of Kansas Medical Center, Kansas City, Kansas
| |
Collapse
|
43
|
Abstract
Fragile X syndrome (FXS) is the leading inherited form of intellectual disability and autism spectrum disorder, and patients can present with severe behavioural alterations, including hyperactivity, impulsivity and anxiety, in addition to poor language development and seizures. FXS is a trinucleotide repeat disorder, in which >200 repeats of the CGG motif in FMR1 leads to silencing of the gene and the consequent loss of its product, fragile X mental retardation 1 protein (FMRP). FMRP has a central role in gene expression and regulates the translation of potentially hundreds of mRNAs, many of which are involved in the development and maintenance of neuronal synaptic connections. Indeed, disturbances in neuroplasticity is a key finding in FXS animal models, and an imbalance in inhibitory and excitatory neuronal circuits is believed to underlie many of the clinical manifestations of this disorder. Our knowledge of the proteins that are regulated by FMRP is rapidly growing, and this has led to the identification of multiple targets for therapeutic intervention, some of which have already moved into clinical trials or clinical practice.
Collapse
|
44
|
Hayward BE, Kumari D, Usdin K. Recent advances in assays for the fragile X-related disorders. Hum Genet 2017; 136:1313-1327. [PMID: 28866801 DOI: 10.1007/s00439-017-1840-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 08/24/2017] [Indexed: 12/17/2022]
Abstract
The fragile X-related disorders are a group of three clinical conditions resulting from the instability of a CGG-repeat tract at the 5' end of the FMR1 transcript. Fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated primary ovarian insufficiency (FXPOI) are disorders seen in carriers of FMR1 alleles with 55-200 repeats. Female carriers of these premutation (PM) alleles are also at risk of having a child who has an FMR1 allele with >200 repeats. Most of these full mutation (FM) alleles are epigenetically silenced resulting in a deficit of the FMR1 gene product, FMRP. This results in fragile X Syndrome (FXS), the most common heritable cause of intellectual disability and autism. The diagnosis and study of these disorders is challenging, in part because the detection of alleles with large repeat numbers has, until recently, been either time-consuming or unreliable. This problem is compounded by the mosaicism for repeat length and/or DNA methylation that is frequently seen in PM and FM carriers. Furthermore, since AGG interruptions in the repeat tract affect the risk that a FM allele will be maternally transmitted, the ability to accurately detect these interruptions in female PM carriers is an additional challenge that must be met. This review will discuss some of the pros and cons of some recently described assays for these disorders, including those that detect FMRP levels directly, as well as emerging technologies that promise to improve the diagnosis of these conditions and to be useful in both basic and translational research settings.
Collapse
Affiliation(s)
- Bruce E Hayward
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA
| | - Daman Kumari
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA
| | - Karen Usdin
- Section on Gene Structure and Disease, Laboratory of Cell and Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, Building 8, Room 2A19, National Institutes of Health, 8 Center Drive MSC 0830, Bethesda, MD, 20892, USA.
| |
Collapse
|
45
|
Polyzos AA, McMurray CT. Close encounters: Moving along bumps, breaks, and bubbles on expanded trinucleotide tracts. DNA Repair (Amst) 2017; 56:144-155. [PMID: 28690053 PMCID: PMC5558859 DOI: 10.1016/j.dnarep.2017.06.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Expansion of simple triplet repeats (TNR) underlies more than 30 severe degenerative diseases. There is a good understanding of the major pathways generating an expansion, and the associated polymerases that operate during gap filling synthesis at these "difficult to copy" sequences. However, the mechanism by which a TNR is repaired depends on the type of lesion, the structural features imposed by the lesion, the assembled replication/repair complex, and the polymerase that encounters it. The relationships among these parameters are exceptionally complex and how they direct pathway choice is poorly understood. In this review, we consider the properties of polymerases, and how encounters with GC-rich or abnormal structures might influence polymerase choice and the success of replication and repair. Insights over the last three years have highlighted new mechanisms that provide interesting choices to consider in protecting genome stability.
Collapse
Affiliation(s)
- Aris A Polyzos
- MBIB Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, United States
| | - Cynthia T McMurray
- MBIB Division, Lawrence Berkeley Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, United States.
| |
Collapse
|