1
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Kock KH, Kimes PK, Gisselbrecht SS, Inukai S, Phanor SK, Anderson JT, Ramakrishnan G, Lipper CH, Song D, Kurland JV, Rogers JM, Jeong R, Blacklow SC, Irizarry RA, Bulyk ML. DNA binding analysis of rare variants in homeodomains reveals homeodomain specificity-determining residues. Nat Commun 2024; 15:3110. [PMID: 38600112 PMCID: PMC11006913 DOI: 10.1038/s41467-024-47396-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 03/29/2024] [Indexed: 04/12/2024] Open
Abstract
Homeodomains (HDs) are the second largest class of DNA binding domains (DBDs) among eukaryotic sequence-specific transcription factors (TFs) and are the TF structural class with the largest number of disease-associated mutations in the Human Gene Mutation Database (HGMD). Despite numerous structural studies and large-scale analyses of HD DNA binding specificity, HD-DNA recognition is still not fully understood. Here, we analyze 92 human HD mutants, including disease-associated variants and variants of uncertain significance (VUS), for their effects on DNA binding activity. Many of the variants alter DNA binding affinity and/or specificity. Detailed biochemical analysis and structural modeling identifies 14 previously unknown specificity-determining positions, 5 of which do not contact DNA. The same missense substitution at analogous positions within different HDs often exhibits different effects on DNA binding activity. Variant effect prediction tools perform moderately well in distinguishing variants with altered DNA binding affinity, but poorly in identifying those with altered binding specificity. Our results highlight the need for biochemical assays of TF coding variants and prioritize dozens of variants for further investigations into their pathogenicity and the development of clinical diagnostics and precision therapies.
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Affiliation(s)
- Kian Hong Kock
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA
| | - Patrick K Kimes
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Stephen S Gisselbrecht
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Sachi Inukai
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Sabrina K Phanor
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - James T Anderson
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Gayatri Ramakrishnan
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Boston Bangalore Biosciences Beginnings Program, Harvard University, Cambridge, MA, USA
| | - Colin H Lipper
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA, USA
| | - Dongyuan Song
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Jesse V Kurland
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
| | - Julia M Rogers
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA
| | - Raehoon Jeong
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA
- Bioinformatics and Integrative Genomics Graduate Program, Harvard University, Cambridge, MA, USA
| | - Stephen C Blacklow
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Department of Cancer Biology, Dana Farber Cancer Institute, Boston, MA, USA
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA
| | - Rafael A Irizarry
- Department of Data Science, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Martha L Bulyk
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, USA.
- Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA, USA.
- Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, MA, USA.
- Bioinformatics and Integrative Genomics Graduate Program, Harvard University, Cambridge, MA, USA.
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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2
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Bernardo P, Cuccurullo C, Rubino M, De Vita G, Terrone G, Bilo L, Coppola A. X-Linked Epilepsies: A Narrative Review. Int J Mol Sci 2024; 25:4110. [PMID: 38612920 PMCID: PMC11012983 DOI: 10.3390/ijms25074110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/03/2024] [Accepted: 04/06/2024] [Indexed: 04/14/2024] Open
Abstract
X-linked epilepsies are a heterogeneous group of epileptic conditions, which often overlap with X-linked intellectual disability. To date, various X-linked genes responsible for epilepsy syndromes and/or developmental and epileptic encephalopathies have been recognized. The electro-clinical phenotype is well described for some genes in which epilepsy represents the core symptom, while less phenotypic details have been reported for other recently identified genes. In this review, we comprehensively describe the main features of both X-linked epileptic syndromes thoroughly characterized to date (PCDH19-related DEE, CDKL5-related DEE, MECP2-related disorders), forms of epilepsy related to X-linked neuronal migration disorders (e.g., ARX, DCX, FLNA) and DEEs associated with recently recognized genes (e.g., SLC9A6, SLC35A2, SYN1, ARHGEF9, ATP6AP2, IQSEC2, NEXMIF, PIGA, ALG13, FGF13, GRIA3, SMC1A). It is often difficult to suspect an X-linked mode of transmission in an epilepsy syndrome. Indeed, different models of X-linked inheritance and modifying factors, including epigenetic regulation and X-chromosome inactivation in females, may further complicate genotype-phenotype correlations. The purpose of this work is to provide an extensive and updated narrative review of X-linked epilepsies. This review could support clinicians in the genetic diagnosis and treatment of patients with epilepsy featuring X-linked inheritance.
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Affiliation(s)
- Pia Bernardo
- Pediatric Psychiatry and Neurology Unit, Department of Neurosciences, Santobono-Pausilipon Children’s Hospital, 80129 Naples, Italy
| | - Claudia Cuccurullo
- Neurology and Stroke Unit, Ospedale del Mare Hospital, ASL Napoli 1 Centro, 80147 Naples, Italy;
| | - Marica Rubino
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, 80131 Naples, Italy (L.B.)
| | - Gabriella De Vita
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131 Naples, Italy;
| | - Gaetano Terrone
- Child Neuropsychiatry Units, Department of Translational Medical Sciences, University Federico II of Naples, 80131 Naples, Italy;
| | - Leonilda Bilo
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, 80131 Naples, Italy (L.B.)
| | - Antonietta Coppola
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University Federico II of Naples, 80131 Naples, Italy (L.B.)
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3
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Gras M, Heide S, Keren B, Valence S, Garel C, Whalen S, Jansen AC, Keymolen K, Stouffs K, Jennesson M, Poirsier C, Lesca G, Depienne C, Nava C, Rastetter A, Curie A, Cuisset L, Des Portes V, Milh M, Charles P, Mignot C, Héron D. Further characterisation of ARX-related disorders in females due to inherited or de novo variants. J Med Genet 2024; 61:103-108. [PMID: 37879892 DOI: 10.1136/jmg-2023-109203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 09/30/2023] [Indexed: 10/27/2023]
Abstract
The Aristaless-related homeobox (ARX) gene is located on the X chromosome and encodes a transcription factor that is essential for brain development. While the clinical spectrum of ARX-related disorders is well described in males, from X linked lissencephaly with abnormal genitalia syndrome to syndromic and non-syndromic intellectual disability (ID), its phenotypic delineation in females is incomplete. Carrier females in ARX families are usually asymptomatic, but ID has been reported in some of them, as well as in others with de novo variants. In this study, we collected the clinical and molecular data of 10 unpublished female patients with de novo ARX pathogenic variants and reviewed the data of 63 females from the literature with either de novo variants (n=10), inherited variants (n=33) or variants of unknown inheritance (n=20). Altogether, the clinical spectrum of females with heterozygous pathogenic ARX variants is broad: 42.5% are asymptomatic, 16.4% have isolated agenesis of the corpus callosum (ACC) or mild symptoms (learning disabilities, autism spectrum disorder, drug-responsive epilepsy) without ID, whereas 41% present with a severe phenotype (ie, ID or developmental and epileptic encephalopathy (DEE)). The ID/DEE phenotype was significantly more prevalent in females carrying de novo variants (75%, n=15/20) versus in those carrying inherited variants (27.3%, n=9/33). ACC was observed in 66.7% (n=24/36) of females who underwent a brain MRI. By refining the clinical spectrum of females carrying ARX pathogenic variants, we show that ID is a frequent sign in females with this X linked condition.
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Affiliation(s)
- Mathilde Gras
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
| | - Solveig Heide
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
- Reference Center for Rare Diseases « Intellectual disabilities of rare causes » Déficiences Intellectuelles de Causes Rares, University Hospital Pitié Salpêtrière, Paris, France
- Doctoral College, Sorbonne University, Paris, France
| | - Boris Keren
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
| | - Stéphanie Valence
- Unit of Pediatric Neurology, APHP Sorbonne Université, Armand-Trousseau Hospital, Paris, France
- Reference Center for Rare Diseases « Intellectual disabilites of rare causes » Déficiences Intellectuelles de Causes Rares, Armand-Trousseau Hospital, Paris, France
| | - Catherine Garel
- Unit of Pediatric Radiology, APHP Sorbonne Université, Armand-Trousseau Hospital, Paris, France
| | - Sandra Whalen
- Department of Clinical Genetics and Reference Center for Rare Diseases « Developmental disorders and syndromes », APHP Sorbonne Université, Armand-Trousseau Hospital, Paris, France
| | - Anna C Jansen
- Neurogenetics Research Group, Vrije Universiteit Brussel, Brussels, Belgium
| | - Kathelijn Keymolen
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Universitair Ziekenhuis Brussel (UZ Brussels), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Katrien Stouffs
- Clinical Sciences, Research Group Reproduction and Genetics, Centre for Medical Genetics, Universitair Ziekenhuis Brussel (UZ Brussels), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Mélanie Jennesson
- Pediatrics Unit, University Hospital of Reims, American Memorial Hospital, Reims, France
| | - Céline Poirsier
- UF génétique clinique, Pôle Femme-Parents-Enfants, CHU Reims, Reims, France
| | - Gaetan Lesca
- Department of Genetics, Referral Center for Developmental Anomalies and Malformative Syndromes, Centre-est HCL, Hospices Civils de Lyon, Lyon, France
| | - Christel Depienne
- Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
| | | | | | - Aurore Curie
- Reference Centre for Rare Diseases « Intellectual disabilities of rare causes », Civil Hospices of Lyon, Lyon, France
- University Lyon 1 Faculty of Medicine Lyon-Est, Lyon, France
| | - Laurence Cuisset
- APHP Centre Université Paris Cité, Service de Médecine Génomique des Maladies de Système et d'Organe, Cochin Hospital, Paris, France
| | - Vincent Des Portes
- Reference Centre for Rare Diseases « Intellectual disabilities of rare causes », Civil Hospices of Lyon, Lyon, France
- University Lyon 1 Faculty of Medicine Lyon-Est, Lyon, France
| | - Mathieu Milh
- Department of Neurology Pediatrics, AP-HM, Hôpital de la Timone, Marseille, France
| | - Perrine Charles
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
- Reference Center for Rare Diseases « Intellectual disabilities of rare causes » Déficiences Intellectuelles de Causes Rares, University Hospital Pitié Salpêtrière, Paris, France
| | - Cyril Mignot
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
- Reference Center for Rare Diseases « Intellectual disabilities of rare causes » Déficiences Intellectuelles de Causes Rares, University Hospital Pitié Salpêtrière, Paris, France
| | - Delphine Héron
- Department of Clinical Genetics, APHP Sorbonne Université, University Hospital Pitié Salpêtrière, Paris, France
- Reference Center for Rare Diseases « Intellectual disabilities of rare causes » Déficiences Intellectuelles de Causes Rares, University Hospital Pitié Salpêtrière, Paris, France
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4
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Brandes N, Goldman G, Wang CH, Ye CJ, Ntranos V. Genome-wide prediction of disease variant effects with a deep protein language model. Nat Genet 2023; 55:1512-1522. [PMID: 37563329 PMCID: PMC10484790 DOI: 10.1038/s41588-023-01465-0] [Citation(s) in RCA: 63] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 07/05/2023] [Indexed: 08/12/2023]
Abstract
Predicting the effects of coding variants is a major challenge. While recent deep-learning models have improved variant effect prediction accuracy, they cannot analyze all coding variants due to dependency on close homologs or software limitations. Here we developed a workflow using ESM1b, a 650-million-parameter protein language model, to predict all ~450 million possible missense variant effects in the human genome, and made all predictions available on a web portal. ESM1b outperformed existing methods in classifying ~150,000 ClinVar/HGMD missense variants as pathogenic or benign and predicting measurements across 28 deep mutational scan datasets. We further annotated ~2 million variants as damaging only in specific protein isoforms, demonstrating the importance of considering all isoforms when predicting variant effects. Our approach also generalizes to more complex coding variants such as in-frame indels and stop-gains. Together, these results establish protein language models as an effective, accurate and general approach to predicting variant effects.
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Affiliation(s)
- Nadav Brandes
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Grant Goldman
- Biological and Medical Informatics Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Charlotte H Wang
- Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Chun Jimmie Ye
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA.
- Parker Institute for Cancer Immunotherapy, University of California, San Francisco, San Francisco, CA, USA.
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA.
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Epidemiology & Biostatistics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
| | - Vasilis Ntranos
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA.
- Department of Epidemiology & Biostatistics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.
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5
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Singh NP, Krumlauf R. Diversification and Functional Evolution of HOX Proteins. Front Cell Dev Biol 2022; 10:798812. [PMID: 35646905 PMCID: PMC9136108 DOI: 10.3389/fcell.2022.798812] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 04/08/2022] [Indexed: 01/07/2023] Open
Abstract
Gene duplication and divergence is a major contributor to the generation of morphological diversity and the emergence of novel features in vertebrates during evolution. The availability of sequenced genomes has facilitated our understanding of the evolution of genes and regulatory elements. However, progress in understanding conservation and divergence in the function of proteins has been slow and mainly assessed by comparing protein sequences in combination with in vitro analyses. These approaches help to classify proteins into different families and sub-families, such as distinct types of transcription factors, but how protein function varies within a gene family is less well understood. Some studies have explored the functional evolution of closely related proteins and important insights have begun to emerge. In this review, we will provide a general overview of gene duplication and functional divergence and then focus on the functional evolution of HOX proteins to illustrate evolutionary changes underlying diversification and their role in animal evolution.
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Affiliation(s)
| | - Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO, United States
- Department of Anatomy and Cell Biology, Kansas University Medical Center, Kansas City, KS, United States
- *Correspondence: Robb Krumlauf,
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6
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Further Delineation of Duplications of ARX Locus Detected in Male Patients with Varying Degrees of Intellectual Disability. Int J Mol Sci 2022; 23:ijms23063084. [PMID: 35328505 PMCID: PMC8955779 DOI: 10.3390/ijms23063084] [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: 02/17/2022] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 11/20/2022] Open
Abstract
The X-linked gene encoding aristaless-related homeobox (ARX) is a bi-functional transcription factor capable of activating or repressing gene transcription, whose mutations have been found in a wide spectrum of neurodevelopmental disorders (NDDs); these include cortical malformations, paediatric epilepsy, intellectual disability (ID) and autism. In addition to point mutations, duplications of the ARX locus have been detected in male patients with ID. These rearrangements include telencephalon ultraconserved enhancers, whose structural alterations can interfere with the control of ARX expression in the developing brain. Here, we review the structural features of 15 gain copy-number variants (CNVs) of the ARX locus found in patients presenting wide-ranging phenotypic variations including ID, speech delay, hypotonia and psychiatric abnormalities. We also report on a further novel Xp21.3 duplication detected in a male patient with moderate ID and carrying a fully duplicated copy of the ARX locus and the ultraconserved enhancers. As consequences of this rearrangement, the patient-derived lymphoblastoid cell line shows abnormal activity of the ARX-KDM5C-SYN1 regulatory axis. Moreover, the three-dimensional (3D) structure of the Arx locus, both in mouse embryonic stem cells and cortical neurons, provides new insight for the functional consequences of ARX duplications. Finally, by comparing the clinical features of the 16 CNVs affecting the ARX locus, we conclude that—depending on the involvement of tissue-specific enhancers—the ARX duplications are ID-associated risk CNVs with variable expressivity and penetrance.
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7
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Poeta L, Padula A, Attianese B, Valentino M, Verrillo L, Filosa S, Shoubridge C, Barra A, Schwartz CE, Christensen J, van Bokhoven H, Helin K, Lioi MB, Collombat P, Gecz J, Altucci L, Di Schiavi E, Miano MG. Histone demethylase KDM5C is a SAHA-sensitive central hub at the crossroads of transcriptional axes involved in multiple neurodevelopmental disorders. Hum Mol Genet 2020; 28:4089-4102. [PMID: 31691806 DOI: 10.1093/hmg/ddz254] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 12/26/2022] Open
Abstract
A disproportional large number of neurodevelopmental disorders (NDDs) is caused by variants in genes encoding transcription factors and chromatin modifiers. However, the functional interactions between the corresponding proteins are only partly known. Here, we show that KDM5C, encoding a H3K4 demethylase, is at the intersection of transcriptional axes under the control of three regulatory proteins ARX, ZNF711 and PHF8. Interestingly, mutations in all four genes (KDM5C, ARX, ZNF711 and PHF8) are associated with X-linked NDDs comprising intellectual disability as a core feature. in vitro analysis of the KDM5C promoter revealed that ARX and ZNF711 function as antagonist transcription factors that activate KDM5C expression and compete for the recruitment of PHF8. Functional analysis of mutations in these genes showed a correlation between phenotype severity and the reduction in KDM5C transcriptional activity. The KDM5C decrease was associated with a lack of repression of downstream target genes Scn2a, Syn1 and Bdnf in the embryonic brain of Arx-null mice. Aiming to correct the faulty expression of KDM5C, we studied the effect of the FDA-approved histone deacetylase inhibitor suberanilohydroxamic acid (SAHA). In Arx-KO murine ES-derived neurons, SAHA was able to rescue KDM5C depletion, recover H3K4me3 signalling and improve neuronal differentiation. Indeed, in ARX/alr-1-deficient Caenorhabditis elegans animals, SAHA was shown to counteract the defective KDM5C/rbr-2-H3K4me3 signalling, recover abnormal behavioural phenotype and ameliorate neuronal maturation. Overall, our studies indicate that KDM5C is a conserved and druggable effector molecule across a number of NDDs for whom the use of SAHA may be considered a potential therapeutic strategy.
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Affiliation(s)
- Loredana Poeta
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy
| | - Agnese Padula
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy.,University of Campania Luigi Vanvitelli, Caserta, Italy
| | - Benedetta Attianese
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy
| | - Mariaelena Valentino
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy
| | - Lucia Verrillo
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy.,University of Campania Luigi Vanvitelli, Caserta, Italy
| | - Stefania Filosa
- Institute of Biosciences and BioResources, National Research Council (CNR), Naples, Italy.,Istituto Neurologico Mediterraneo (Neuromed), Pozzilli, Isernia, Italy
| | - Cheryl Shoubridge
- Intellectual Disability Research, Adelaide Medical School, The University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Adriano Barra
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy
| | | | - Jesper Christensen
- University of Copenhagen, Biotech Research and Innovation Centre (BRIC), Copenhagen, Denmark.,University of Copenhagen, The Novo Nordisk Foundation Center for Stem Cell Biology (Danstem), Copenhagen, Denmark
| | - Hans van Bokhoven
- Department of Human Genetics, Donders Institute for Brain, Behaviour and Cognition, Radboudumc, Nijmegen, The Netherlands
| | - Kristian Helin
- University of Copenhagen, Biotech Research and Innovation Centre (BRIC), Copenhagen, Denmark.,University of Copenhagen, The Novo Nordisk Foundation Center for Stem Cell Biology (Danstem), Copenhagen, Denmark
| | | | | | - Jozef Gecz
- Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, Australia
| | - Lucia Altucci
- University of Campania Luigi Vanvitelli, Caserta, Italy
| | - Elia Di Schiavi
- Institute of Biosciences and BioResources, National Research Council (CNR), Naples, Italy
| | - Maria Giuseppina Miano
- Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", National Research Council (CNR), Naples, Italy
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8
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Miller CR, Lee K, Pfau RB, Reshmi SC, Corsmeier DJ, Hashimoto S, Dave-Wala A, Jayaraman V, Koboldt D, Matthews T, Mouhlas D, Stein M, McKinney A, Grossman T, Kelly BJ, White P, Magrini V, Wilson RK, Mardis ER, Cottrell CE. Disease-associated mosaic variation in clinical exome sequencing: a two-year pediatric tertiary care experience. Cold Spring Harb Mol Case Stud 2020; 6:mcs.a005231. [PMID: 32371413 PMCID: PMC7304353 DOI: 10.1101/mcs.a005231] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 04/29/2020] [Indexed: 11/25/2022] Open
Abstract
Exome sequencing (ES) has become an important tool in pediatric genomic medicine, improving identification of disease-associated variation due to assay breadth. Depth is also afforded by ES, enabling detection of lower-frequency mosaic variation compared to Sanger sequencing in the studied tissue, thus enhancing diagnostic yield. Within a pediatric tertiary-care hospital, we report two years of clinical ES data from probands evaluated for genetic disease to assess diagnostic yield, characteristics of causal variants, and prevalence of mosaicism among disease-causing variants. Exome-derived, phenotype-driven variant data from 357 probands was analyzed concurrent with parental ES data, when available. Blood was the source of nucleic acid. Sequence read alignments were manually reviewed for all assessed variants. Sanger sequencing was used for suspected de novo or mosaic variation. Clinical provider notes were reviewed to determine concordance between laboratory-reported data and the ordering provider's interpretation of variant-associated disease causality. Laboratory-derived diagnostic yield and provider-substantiated diagnoses had 91.4% concordance. The cohort returned 117 provider-substantiated diagnoses among 115 probands for a diagnostic yield of 32.2%. De novo variants represented 64.9% of disease-associated variation within trio analyses. Among the 115 probands, five harbored disease-associated somatic mosaic variation. Two additional probands were observed to inherit a disease-associated variant from an unaffected mosaic parent. Among inheritance patterns, de novo variation was the most frequent disease etiology. Somatic mosaicism is increasingly recognized as a significant contributor to genetic disease, particularly with increased sequence depth attainable from ES. This report highlights the potential and importance of detecting mosaicism in ES.
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Affiliation(s)
- Cecelia R Miller
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology
| | - Kristy Lee
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology
| | - Ruthann B Pfau
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Shalini C Reshmi
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Donald J Corsmeier
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Sayaka Hashimoto
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Ashita Dave-Wala
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Vijayakumar Jayaraman
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Daniel Koboldt
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Theodora Matthews
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Danielle Mouhlas
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Maggie Stein
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Aimee McKinney
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Tom Grossman
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Benjamin J Kelly
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA
| | - Peter White
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Vincent Magrini
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Richard K Wilson
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Elaine R Mardis
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Catherine E Cottrell
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio 43205, USA.,Department of Pathology.,Department of Pediatrics, The Ohio State University, Columbus, Ohio 43210, USA
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9
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Traversa A, Marchionni E, Giovannetti A, Genovesi ML, Panzironi N, Margiotti K, Napoli G, Piceci Sparascio F, De Luca A, Petrizzelli F, Carella M, Cardona F, Bernardo S, Manganaro L, Mazza T, Pizzuti A, Caputo V. Heterozygous nonsense ARX mutation in a family highlights the complexity of clinical and molecular diagnosis in case of chromosomal and single gene disorder co-inheritance. Mol Genet Genomic Med 2020; 8:e1336. [PMID: 32519823 PMCID: PMC7434725 DOI: 10.1002/mgg3.1336] [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] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/08/2020] [Accepted: 05/12/2020] [Indexed: 11/17/2022] Open
Abstract
Background Corpus callosum agenesis (ACC) is one of the most frequent Central Nervous System (CNS) malformations. However, genetics underlying isolated forms is still poorly recognized. Here, we report on two female familial cases with partial ACC. The proband shows isolated partial ACC and a mild neurodevelopmental phenotype. A fetus from a previous interrupted pregnancy exhibited a complex phenotype including partial ACC and the occurrence of a de novo 17q12 microduplication, which was interpreted as probably disease‐causing. Methods A trio‐based clinical exome sequencing (CES) was performed. Results Clinical exome sequencing data analysis led to identifying a heterozygous nonsense variant (NM_139058.3:c.922G>T; NP_620689.1:p.Glu308Ter) in the aristaless related homeobox gene (ARX) in the proband, with a putative de novo occurrence, producing a hypothetical protein lacking two essential domains. Sanger analysis confirmed the wild‐type status of both parents in different tissues, and disclosed the occurrence of the nonsense variant in the fetus of the interrupted pregnancy, suggesting a formerly unrecognized contribution of the ARX mutation to the fetus' phenotype and gonadal or gonadosomatic mosaicism in one of the parents. Conclusion This study describes the phenotype associated with a heterozygous loss of function variant in ARX. Moreover, it highlights the importance of investigating both chromosomal and genetic contributions in cases of complex syndromic phenotypes involving CNS.
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Affiliation(s)
- Alice Traversa
- Laboratory of Clinical Genomics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Enrica Marchionni
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Agnese Giovannetti
- Laboratory of Clinical Genomics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Maria L Genovesi
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Noemi Panzironi
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | | | - Giulia Napoli
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Francesca Piceci Sparascio
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.,UOS Diagnosi Genetica Molecolare, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Alessandro De Luca
- UOS Diagnosi Genetica Molecolare, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Francesco Petrizzelli
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.,Laboratory of Bioinformatics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Massimo Carella
- Laboratory of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Francesco Cardona
- Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Silvia Bernardo
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy.,Department of Radiological, Oncological, and Pathological Anatomy Sciences, Sapienza University of Rome, Rome, Italy
| | - Lucia Manganaro
- Department of Radiological, Oncological, and Pathological Anatomy Sciences, Sapienza University of Rome, Rome, Italy
| | - Tommaso Mazza
- Laboratory of Bioinformatics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy
| | - Antonio Pizzuti
- Laboratory of Clinical Genomics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo (FG), Italy.,Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Viviana Caputo
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
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10
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Thai MHN, Gardner A, Redpath L, Mattiske T, Dearsley O, Shaw M, Vulto-van Silfhout AT, Pfundt R, Dixon J, McGaughran J, Pérez-Jurado LA, Gécz J, Shoubridge C. Constraint and conservation of paired-type homeodomains predicts the clinical outcome of missense variants of uncertain significance. Hum Mutat 2020; 41:1407-1424. [PMID: 32383243 DOI: 10.1002/humu.24034] [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: 10/30/2019] [Revised: 02/26/2020] [Accepted: 05/03/2020] [Indexed: 12/30/2022]
Abstract
The need to interpret the pathogenicity of novel missense variants of unknown significance identified in the homeodomain of X-chromosome aristaless-related homeobox (ARX) gene prompted us to assess the utility of conservation and constraint across these domains in multiple genes compared to conventional in vitro functional analysis. Pathogenic missense variants clustered in the homeodomain of ARX contribute to intellectual disability (ID) and epilepsy, with and without brain malformation in affected males. Here we report novel c.1112G>A, p.Arg371Gln and c.1150C>T, p.Arg384Cys variants in male patients with ID and severe seizures. The third case of a male patient with a c.1109C>T, p.Ala370Val variant is perhaps the first example of ID and autism spectrum disorder (ASD), without seizures or brain malformation. We compiled data sets of pathogenic variants from ClinVar and presumed benign variation from gnomAD and demonstrated that the high levels of sequence conservation and constraint of benign variation within the homeodomain impacts upon the ability of publicly available in silico prediction tools to accurately discern likely benign from likely pathogenic variants in these data sets. Despite this, considering the inheritance patterns of the genes and disease variants with the conservation and constraint of disease variants affecting the homeodomain in conjunction with current clinical assessments may assist in predicting the pathogenicity of missense variants, particularly for genes with autosomal recessive and X-linked patterns of disease inheritance, such as ARX. In vitro functional analysis demonstrates that the transcriptional activity of all three variants was diminished compared to ARX-Wt. We review the associated phenotypes of the published cases of patients with ARX homeodomain variants and propose expansion of the ARX-related phenotype to include severe ID and ASD without brain malformations or seizures. We propose that the use of the constraint and conservation data in conjunction with consideration of the patient phenotype and inheritance pattern may negate the need for the experimental functional validation currently required to achieve a diagnosis.
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Affiliation(s)
- Monica H N Thai
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Alison Gardner
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Laura Redpath
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Tessa Mattiske
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Oliver Dearsley
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Marie Shaw
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | | | - Rolph Pfundt
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joanne Dixon
- Genetic Health Service NZ-South Island Hub, Christchurch Hospital, Christchurch, New Zealand
| | - Julie McGaughran
- Genetic Health Queensland, MNHHS, Brisbane and School of Medicine, The University of Queensland, Brisbane, Queensland, Australia
| | - Luis A Pérez-Jurado
- Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia.,South Australian Clinical Genetics Service, SA Pathology, Adelaide, South Australia, Australia.,Hospital del Mar Research Institute, Network Research Centre for Rare Diseases and Universitat Pompeu Fabra, Barcelona, Spain
| | - Jozef Gécz
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia.,South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
| | - Cheryl Shoubridge
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
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11
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Shoubridge C, Jackson M, Grinton B, Berkovic SF, Scheffer IE, Huskins S, Thomas A, Ware T. Splice variant in ARX leading to loss of C-terminal region in a boy with intellectual disability and infantile onset developmental and epileptic encephalopathy. Am J Med Genet A 2019; 179:1483-1490. [PMID: 31145546 DOI: 10.1002/ajmg.a.61216] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/07/2019] [Accepted: 05/05/2019] [Indexed: 02/06/2023]
Abstract
Pathogenic variants in the X-chromosome Aristaless-related homeobox (ARX) gene contribute to intellectual disability, epilepsy, and associated comorbidities in affected males. Here, we report a novel splice variant in ARX in a family with three affected individuals. The proband had early onset developmental and epileptic encephalopathy, his brother and mother had severe and mild intellectual disability, respectively. Massively parallel sequencing identified a novel c.1449-1G>C in intron 4 of the ARX gene, predicted to abolish the splice acceptor site, retaining intron 4 and leading to a premature termination codon immediately after exon 4. As exon 5 is the last exon of the ARX gene, the premature termination codon at position p.L484* would be predicted to escape nonsense-mediated mRNA decay, potentially producing at least some C-terminally truncated protein. Analysis of cDNA from patient lymphoblastoid cells confirmed retention of intron 4 and loss of detectable expression of ARX mRNA across exon 4 to exon 5. We review published cases of variants that lead to altered or early termination of the ARX protein, but not complete loss of function, and are associated with phenotypes of intellectual disability and infantile onset developmental and epileptic encephalopathies, including Ohtahara and West syndromes. Taken together, this novel splice variant retaining intron 4 is likely to be the cause of the early onset developmental and epileptic encephalopathy in the proband.
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Affiliation(s)
- Cheryl Shoubridge
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Matilda Jackson
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.,Robinson Research Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Bronwyn Grinton
- Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Samuel F Berkovic
- Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Ingrid E Scheffer
- Department of Medicine, University of Melbourne, Austin Health, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Florey and Murdoch Children's Research Institutes, Melbourne, Victoria, Australia
| | - Shannon Huskins
- Department of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Alison Thomas
- Department of Medical Imaging, Royal Hobart Hospital, Hobart, Tasmania, Australia
| | - Tyson Ware
- Department of Paediatrics, Royal Hobart Hospital, Hobart, Tasmania, Australia
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12
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Mattiske T, Tan MH, Dearsley O, Cloosterman D, Hii CS, Gécz J, Shoubridge C. Regulating transcriptional activity by phosphorylation: A new mechanism for the ARX homeodomain transcription factor. PLoS One 2018; 13:e0206914. [PMID: 30419043 PMCID: PMC6231642 DOI: 10.1371/journal.pone.0206914] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 10/22/2018] [Indexed: 01/08/2023] Open
Abstract
Aristaless-related homeobox (ARX) gene encodes a paired-type homeodomain transcription factor with critical roles in development. Here we identify that ARX protein is phosphorylated. Using mass spectrometry and in vitro kinase assays we identify phosphorylation at serines 37, 67 and 174. Through yeast-2-hybrid and CoIP we identified PICK1 (Protein interacting with C kinase 1) binding with the C-terminal region of ARX. PICK1 is a scaffold protein known to facilitate phosphorylation of protein partners by protein kinase C alpha (PRKCA). We confirm that ARX is phosphorylated by PRKCA and demonstrate phosphorylation at serine 174. We demonstrate that phosphorylation is required for correct transcriptional activity of the ARX protein using transcriptome-wide analysis of gene expression of phospho-null mutants (alanines replacing serines) compared to ARX wild-type (ARX-WT) overexpressed in pancreatic alpha TC cells. Compared to untransfected cells, ARX-WT overexpression significantly altered expression of 70 genes (Log2FC >+/-1.0, P-value <0.05). There were fewer genes with significantly altered expression compared to untransfected cells with the double phospho-null mutant Ser37Ala+Ser67Ala (26%) and Ser174Ala (39%), respectively. We demonstrate that the c-terminal region of ARX required to bind PICK1 causes a shift in PICK1 subcellular localisation to the nucleus to co-locate with the ARX protein, and truncation of this C-terminal region leads to the same loss of transcriptional activation as S174A mutant. In conclusion, we show that ARX is phosphorylated at several sites and that this modification affects its transcriptional activity.
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Affiliation(s)
- Tessa Mattiske
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | - May H. Tan
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
| | - Oliver Dearsley
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Robinson Research Institute, University of Adelaide, Adelaide, Australia
| | | | - Charles S. Hii
- Department of Immunopathology, SA-Pathology, Adelaide, Australia
| | - Jozef Gécz
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Robinson Research Institute, University of Adelaide, Adelaide, Australia
- Healthy Mothers and Babies, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Cheryl Shoubridge
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Robinson Research Institute, University of Adelaide, Adelaide, Australia
- * E-mail:
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13
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Moey C, Topper S, Karn M, Johnson AK, Das S, Vidaurre J, Shoubridge C. Reinitiation of mRNA translation in a patient with X-linked infantile spasms with a protein-truncating variant in ARX. Eur J Hum Genet 2015; 24:681-9. [PMID: 26306640 DOI: 10.1038/ejhg.2015.176] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/30/2015] [Accepted: 07/03/2015] [Indexed: 12/30/2022] Open
Abstract
Mutations in the Aristaless-related homeobox gene (ARX) lead to a range of X-linked intellectual disability phenotypes, with truncating variants generally resulting in severe X-linked lissencephaly with ambiguous genitalia (XLAG), and polyalanine expansions and missense variants resulting in infantile spasms. We report two male patients with early-onset infantile spasms in whom a novel c.34G>T (p.(E12*)) variant was identified in the ARX gene. A similar variant c.81C>G (p.(Y27*)), has previously been described in two affected cousins with early-onset infantile spasms, leading to reinitiation of ARX mRNA translation resulting in an N-terminal truncated protein. We show that the novel c.34G>T (p.(E12*)) variant also reinitiated mRNA translation at the next AUG codon (c.121-123 (p.M41)), producing the same N-terminally truncated protein. The production of both of these truncated proteins was demonstrated to be at markedly reduced levels using in vitro cell assays. Using luciferase reporter assays, we demonstrate that transcriptional repression capacity of ARX was diminished by both the loss of the N-terminal corepressor octapeptide domain, as a consequence of truncation, and the marked reduction in mutant protein expression. Our study indicates that premature termination mutations very early in ARX lead to reinitiation of translation to produce N-terminally truncated protein at markedly reduced levels of expression. We conclude that even low levels of N-terminally truncated ARX is sufficient to improve the patient's phenotype compared with the severe phenotype of XLAG that includes malformations of the brain and genitalia normally seen in complete loss-of-function mutations in ARX.
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Affiliation(s)
- Ching Moey
- Department of Paediatrics, School of Peadiatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.,Robinson Research Institute, Faculty of Health Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Scott Topper
- Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Mary Karn
- Nationwide Children's Hospital, Columbus, OH, USA
| | | | - Soma Das
- Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Jorge Vidaurre
- Nationwide Children's Hospital, The Ohio State University, Columbus, OH, USA
| | - Cheryl Shoubridge
- Department of Paediatrics, School of Peadiatrics and Reproductive Health, University of Adelaide, Adelaide, SA, Australia.,Robinson Research Institute, Faculty of Health Sciences, University of Adelaide, Adelaide, SA, Australia
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14
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Deng H, Zheng W, Song Z. Genetics, Molecular Biology, and Phenotypes of X-Linked Epilepsy. Mol Neurobiol 2013; 49:1166-80. [DOI: 10.1007/s12035-013-8589-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Accepted: 11/05/2013] [Indexed: 11/25/2022]
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15
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Ye W, Lin W, Tartakoff AM, Ma Q, Tao T. Nuclear import of aristaless-related homeobox protein via its NLS1 regulates its transcriptional function. Mol Cell Biochem 2013; 381:221-31. [PMID: 23771350 DOI: 10.1007/s11010-013-1706-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 05/24/2013] [Indexed: 10/26/2022]
Abstract
Nucleocytoplasmic transport of transcription factors is essential in eukaryotes. We previously reported the presence of two functional NLSs in the homeodomain protein, aristaless-related homeobox (Arx) protein, which is a key transcriptional repressor of LMO1, SHOX2, and PAX4 during development. NLS2, that overlaps the homeodomain, is recognized directly by multiple importin βs, but not by importin αs. In this study, we found that the N-terminal NLS1 of Arx is targeted by multiple importin α proteins, including importin α3 and α5. Both in vivo and in vitro assays demonstrated that nuclear import of Arx via NLS1 is mediated by the importin α/β pathway. Mutagenesis analysis indicated that two basic amino acids, (84)K and (87)R, are essential to the function of NLS1, and that their mutation prevents interactions of Arx with importin αs. Interestingly, inhibition of nuclear import of Arx via NLS1 clearly attenuates its ability of transcriptional repression, suggesting that nuclear import of Arx via NLS1 contributes to its transcriptional function.
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Affiliation(s)
- Wenduo Ye
- Xiamen University School of Life Sciences, Xiamen, Fujian, China
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16
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Poeta L, Fusco F, Drongitis D, Shoubridge C, Manganelli G, Filosa S, Paciolla M, Courtney M, Collombat P, Lioi M, Gecz J, Ursini M, Miano M. A regulatory path associated with X-linked intellectual disability and epilepsy links KDM5C to the polyalanine expansions in ARX. Am J Hum Genet 2013; 92:114-25. [PMID: 23246292 DOI: 10.1016/j.ajhg.2012.11.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Revised: 06/07/2012] [Accepted: 11/13/2012] [Indexed: 10/27/2022] Open
Abstract
Intellectual disability (ID) and epilepsy often occur together and have a dramatic impact on the development and quality of life of the affected children. Polyalanine (polyA)-expansion-encoding mutations of aristaless-related homeobox (ARX) cause a spectrum of X-linked ID (XLID) diseases and chronic epilepsy, including infantile spasms. We show that lysine-specific demethylase 5C (KDM5C), a gene known to be mutated in XLID-affected children and involved in chromatin remodeling, is directly regulated by ARX through the binding in a conserved noncoding element. We have studied altered ARX carrying various polyA elongations in individuals with XLID and/or epilepsy. The changes in polyA repeats cause hypomorphic ARX alterations, which exhibit a decreased trans-activity and reduced, but not abolished, binding to the KDM5C regulatory region. The altered functioning of the mutants tested is likely to correlate with the severity of XLID and/or epilepsy. By quantitative RT-PCR, we observed a dramatic Kdm5c mRNA downregulation in murine Arx-knockout embryonic and neural stem cells. Such Kdm5c mRNA diminution led to a severe decrease in the KDM5C content during in vitro neuronal differentiation, which inversely correlated with an increase in H3K4me3 signal. We established that ARX polyA alterations damage the regulation of KDM5C expression, and we propose a potential ARX-dependent path acting via chromatin remodeling.
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17
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Mattiske TR, Tan MH, Gécz J, Shoubridge C. Challenges of "sticky" co-immunoprecipitation: polyalanine tract protein-protein interactions. Methods Mol Biol 2013; 1017:121-133. [PMID: 23719912 DOI: 10.1007/978-1-62703-438-8_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Co-immunoprecipitation (Co-IP) (followed by immunoblotting) is a technique widely used to characterize specific protein-protein interactions. Investigating interactions of proteins containing "sticky" polyalanine (PolyA) tracts encounters difficulties using conventional Co-IP procedures. Here, we present strategies to specifically capture proteins containing these difficult PolyA tracts, enabling subsequent robust detection of interacting proteins by Co-IP.
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Affiliation(s)
- T R Mattiske
- Department of Paediatrics, University of Adelaide, Adelaide, SA, Australia
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18
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Huang L, Jolly LA, Willis-Owen S, Gardner A, Kumar R, Douglas E, Shoubridge C, Wieczorek D, Tzschach A, Cohen M, Hackett A, Field M, Froyen G, Hu H, Haas SA, Ropers HH, Kalscheuer VM, Corbett MA, Gecz J. A noncoding, regulatory mutation implicates HCFC1 in nonsyndromic intellectual disability. Am J Hum Genet 2012; 91:694-702. [PMID: 23000143 DOI: 10.1016/j.ajhg.2012.08.011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 06/26/2012] [Accepted: 08/13/2012] [Indexed: 11/28/2022] Open
Abstract
The discovery of mutations causing human disease has so far been biased toward protein-coding regions. Having excluded all annotated coding regions, we performed targeted massively parallel resequencing of the nonrepetitive genomic linkage interval at Xq28 of family MRX3. We identified in the binding site of transcription factor YY1 a regulatory mutation that leads to overexpression of the chromatin-associated transcriptional regulator HCFC1. When tested on embryonic murine neural stem cells and embryonic hippocampal neurons, HCFC1 overexpression led to a significant increase of the production of astrocytes and a considerable reduction in neurite growth. Two other nonsynonymous, potentially deleterious changes have been identified by X-exome sequencing in individuals with intellectual disability, implicating HCFC1 in normal brain function.
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Affiliation(s)
- Lingli Huang
- Genetics and Molecular Pathology, SA Pathology, North Adelaide, SA 5006, Australia
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19
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Olivetti PR, Noebels JL. Interneuron, interrupted: molecular pathogenesis of ARX mutations and X-linked infantile spasms. Curr Opin Neurobiol 2012; 22:859-65. [PMID: 22565167 DOI: 10.1016/j.conb.2012.04.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 04/09/2012] [Indexed: 11/17/2022]
Abstract
X-linked Infantile Spasms Syndrome (ISSX) is a catastrophic epilepsy of early childhood with intractable seizures, intellectual disability, and poor prognosis. A spectrum of mutations in the Aristaless-Related Homeobox gene (ARX) has been linked to ISSX, and downstream targets of this interneuron-expressed transcription factor are being defined. Recent advances combining in vitro and in vivo methods have unveiled complex interactions between Arx and its binding partners and their effects on cell migration and maturation that can help explain the diversity of ARX phenotypes. New mutant mouse models of Arx-induced pathology, including a recent human triplet-repeat expansion mutation with a phenotype of infantile spasms and electrographic seizures, provide valuable tools for exploring the pathophysiology of Arx and substrates for testing novel therapies.
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Affiliation(s)
- Pedro R Olivetti
- Department of Neurology, Baylor College of Medicine, Houston, TX 77030, United States
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