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Shi SQ, Mahoney CE, Houdek P, Zhao W, Anderson MP, Zhuo X, Beaudet A, Sumova A, Scammell TE, Johnson CH. Circadian Rhythms and Sleep Are Dependent Upon Expression Levels of Key Ubiquitin Ligase Ube3a. Front Behav Neurosci 2022; 16:837523. [PMID: 35401134 PMCID: PMC8989470 DOI: 10.3389/fnbeh.2022.837523] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/09/2022] [Indexed: 11/13/2022] Open
Abstract
Normal neurodevelopment requires precise expression of the key ubiquitin ligase gene Ube3a. Comparing newly generated mouse models for Ube3a downregulation (models of Angelman syndrome) vs. Ube3a upregulation (models for autism), we find reciprocal effects of Ube3a gene dosage on phenotypes associated with circadian rhythmicity, including the amount of locomotor activity. Consistent with results from neurons in general, we find that Ube3a is imprinted in neurons of the suprachiasmatic nuclei (SCN), the pacemaking circadian brain locus, despite other claims that SCN neurons were somehow exceptional to these imprinting rules. In addition, Ube3a-deficient mice lack the typical drop in wake late in the dark period and have blunted responses to sleep deprivation. Suppression of physical activity by light in Ube3a-deficient mice is not due to anxiety as measured by behavioral tests and stress hormones; quantification of stress hormones may provide a mechanistic link to sleep alteration and memory deficits caused by Ube3a deficiency, and serve as an easily measurable biomarker for evaluating potential therapeutic treatments for Angelman syndrome. We conclude that reduced Ube3a gene dosage affects not only neurodevelopment but also sleep patterns and circadian rhythms.
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Affiliation(s)
- Shu-qun Shi
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Carrie E. Mahoney
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, United States
| | - Pavel Houdek
- Laboratory of Biological Rhythms, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Wenling Zhao
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, United States
| | - Matthew P. Anderson
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, United States
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States
| | - Xinming Zhuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | | | - Alena Sumova
- Laboratory of Biological Rhythms, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Thomas E. Scammell
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA, United States
| | - Carl Hirschie Johnson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- *Correspondence: Carl Hirschie Johnson,
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2
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Yang L, Shu X, Mao S, Wang Y, Du X, Zou C. Genotype-Phenotype Correlations in Angelman Syndrome. Genes (Basel) 2021; 12:987. [PMID: 34203304 PMCID: PMC8304328 DOI: 10.3390/genes12070987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/15/2021] [Accepted: 06/23/2021] [Indexed: 12/12/2022] Open
Abstract
Angelman syndrome (AS) is a rare neurodevelopmental disease that is caused by the loss of function of the maternal copy of ubiquitin-protein ligase E3A (UBE3A) on the chromosome 15q11-13 region. AS is characterized by global developmental delay, severe intellectual disability, lack of speech, happy disposition, ataxia, epilepsy, and distinct behavioral profile. There are four molecular mechanisms of etiology: maternal deletion of chromosome 15q11-q13, paternal uniparental disomy of chromosome 15q11-q13, imprinting defects, and maternally inherited UBE3A mutations. Different genetic types may show different phenotypes in performance, seizure, behavior, sleep, and other aspects. AS caused by maternal deletion of 15q11-13 appears to have worse development, cognitive skills, albinism, ataxia, and more autistic features than those of other genotypes. Children with a UBE3A mutation have less severe phenotypes and a nearly normal development quotient. In this review, we proposed to review genotype-phenotype correlations based on different genotypes. Understanding the pathophysiology of the different genotypes and the genotype-phenotype correlations will offer an opportunity for individualized treatment and genetic counseling. Genotype-phenotype correlations based on larger data should be carried out for identifying new treatment modalities.
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Affiliation(s)
- Lili Yang
- Department of Genetics and Metabolism, Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China;
| | - Xiaoli Shu
- Department of Laboratory Center, Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China;
| | - Shujiong Mao
- Division of Neonatology, Department of Pediatrics, Hangzhou First People’s Hospital, Zhejiang University School of Medicine, Hangzhou 310052, China;
| | - Yi Wang
- Department of Neurology, Children’s Hospital of Fudan University, Shanghai 201102, China; (Y.W.); (X.D.)
| | - Xiaonan Du
- Department of Neurology, Children’s Hospital of Fudan University, Shanghai 201102, China; (Y.W.); (X.D.)
| | - Chaochun Zou
- Department of Endocrinology, Children’s Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
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3
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Kawabe H, Stegmüller J. The role of E3 ubiquitin ligases in synapse function in the healthy and diseased brain. Mol Cell Neurosci 2021; 112:103602. [DOI: 10.1016/j.mcn.2021.103602] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 01/06/2021] [Accepted: 02/02/2021] [Indexed: 02/08/2023] Open
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4
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Maranga C, Fernandes TG, Bekman E, da Rocha ST. Angelman syndrome: a journey through the brain. FEBS J 2020; 287:2154-2175. [PMID: 32087041 DOI: 10.1111/febs.15258] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/02/2020] [Accepted: 02/21/2020] [Indexed: 12/31/2022]
Abstract
Angelman syndrome (AS) is an incurable neurodevelopmental disease caused by loss of function of the maternally inherited UBE3A gene. AS is characterized by a defined set of symptoms, namely severe developmental delay, speech impairment, uncontrolled laughter, and ataxia. Current understanding of the pathophysiology of AS relies mostly on studies using the murine model of the disease, although alternative models based on patient-derived stem cells are now emerging. Here, we summarize the literature of the last decade concerning the three major brain areas that have been the subject of study in the context of AS: hippocampus, cortex, and the cerebellum. Our comprehensive analysis highlights the major phenotypes ascribed to the different brain areas. Moreover, we also discuss the major drawbacks of current models and point out future directions for research in the context of AS, which will hopefully lead us to an effective treatment of this condition in humans.
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Affiliation(s)
- Carina Maranga
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Tiago G Fernandes
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Evguenia Bekman
- Department of Bioengineering and iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.,The Discoveries Centre for Regenerative and Precision Medicine, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Simão Teixeira da Rocha
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
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5
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Rhon-Calderon EA, Vrooman LA, Riesche L, Bartolomei MS. The effects of Assisted Reproductive Technologies on genomic imprinting in the placenta. Placenta 2019; 84:37-43. [PMID: 30871810 DOI: 10.1016/j.placenta.2019.02.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/19/2019] [Accepted: 02/25/2019] [Indexed: 12/29/2022]
Abstract
The placenta is a complex and poorly understood organ, which serves as the connection between the mother and the developing fetus. Genomic imprinting, defined as a regulatory process resulting in the expression of a gene in a parent-of-origin-specific manner, plays an important role in fetal development and placental function. Disturbances that occur during the establishment and maintenance of imprinting could compromise the placenta and fetus, and ultimately, offspring health. Assisted Reproductive Technologies (ART) have been widely used to overcome infertility, however experimental studies have shown that ART procedures affect placentation and the expression of imprinted genes. Here we briefly review the role of imprinted genes in placental development and the evidence from mouse and human studies suggesting ART disrupts imprinted gene regulation in the placenta.
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Affiliation(s)
- Eric A Rhon-Calderon
- Epigenetics Institute, Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104-6058, USA
| | - Lisa A Vrooman
- Epigenetics Institute, Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104-6058, USA
| | - Laren Riesche
- Epigenetics Institute, Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104-6058, USA; Department of Family and Community Health, Claire M. Fagin School of Nursing, University of Pennsylvania, Philadelphia, PA, USA
| | - Marisa S Bartolomei
- Epigenetics Institute, Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Smilow Center for Translational Research, 3400 Civic Center Blvd, Bldg 421, Philadelphia, PA, 19104-6058, USA.
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6
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Kim KC, Gonzales EL, Lázaro MT, Choi CS, Bahn GH, Yoo HJ, Shin CY. Clinical and Neurobiological Relevance of Current Animal Models of Autism Spectrum Disorders. Biomol Ther (Seoul) 2016; 24:207-43. [PMID: 27133257 PMCID: PMC4859786 DOI: 10.4062/biomolther.2016.061] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 04/05/2016] [Indexed: 12/24/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social and communication impairments, as well as repetitive and restrictive behaviors. The phenotypic heterogeneity of ASD has made it overwhelmingly difficult to determine the exact etiology and pathophysiology underlying the core symptoms, which are often accompanied by comorbidities such as hyperactivity, seizures, and sensorimotor abnormalities. To our benefit, the advent of animal models has allowed us to assess and test diverse risk factors of ASD, both genetic and environmental, and measure their contribution to the manifestation of autistic symptoms. At a broader scale, rodent models have helped consolidate molecular pathways and unify the neurophysiological mechanisms underlying each one of the various etiologies. This approach will potentially enable the stratification of ASD into clinical, molecular, and neurophenotypic subgroups, further proving their translational utility. It is henceforth paramount to establish a common ground of mechanistic theories from complementing results in preclinical research. In this review, we cluster the ASD animal models into lesion and genetic models and further classify them based on the corresponding environmental, epigenetic and genetic factors. Finally, we summarize the symptoms and neuropathological highlights for each model and make critical comparisons that elucidate their clinical and neurobiological relevance.
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Affiliation(s)
- Ki Chan Kim
- Department of Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.,Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea
| | - Edson Luck Gonzales
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - María T Lázaro
- Program in Neurogenetics, Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Chang Soon Choi
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
| | - Geon Ho Bahn
- Department of Neuropsychiatry, School of Medicine, Kyung Hee University, Seoul 02447, Republic of Korea
| | - Hee Jeong Yoo
- Department of Neuropsychiatry, Seoul National University Bungdang Hospital, Seongnam 13620, Republic of Korea
| | - Chan Young Shin
- Center for Neuroscience Research, SMART Institute of Advanced Biomedical Sciences, Konkuk University, Seoul 05029, Republic of Korea.,School of Medicine, Konkuk University, Seoul 05029, Republic of Korea
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Upadhyay A, Amanullah A, Chhangani D, Mishra R, Mishra A. Selective multifaceted E3 ubiquitin ligases barricade extreme defense: Potential therapeutic targets for neurodegeneration and ageing. Ageing Res Rev 2015; 24:138-59. [PMID: 26247845 DOI: 10.1016/j.arr.2015.07.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Revised: 06/24/2015] [Accepted: 07/30/2015] [Indexed: 12/24/2022]
Abstract
Efficient and regular performance of Ubiquitin Proteasome System and Autophagy continuously eliminate deleterious accumulation of nonnative protiens. In cellular quality control system, E3 ubiquitin ligases are significant employees for defense mechanism against abnormal toxic proteins. Few findings indicate that lack of functions of E3 ubiquitin ligases can be a causative factor of neurodevelopmental disorders, neurodegeneration, cancer and ageing. However, the detailed molecular pathomechanism implying E3 ubiquitin ligases in cellular functions in multifactorial disease conditions are not well understood. This article systematically represents the unique characteristics, molecular nature, and recent developments in the knowledge of neurobiological functions of few crucial E3 ubiquitin ligases. Here, we review recent literature on the roles of E6-AP, HRD1 and ITCH E3 ubiquitin ligases in the neuro-pathobiological mechanisms, with precise focus on the processes of neurodegeneration, and thereby propose new lines of potential targets for therapeutic interventions.
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Abstract
In this review we summarize the clinical and genetic aspects of Angelman syndrome (AS), its molecular and cellular underpinnings, and current treatment strategies. AS is a neurodevelopmental disorder characterized by severe cognitive disability, motor dysfunction, speech impairment, hyperactivity, and frequent seizures. AS is caused by disruption of the maternally expressed and paternally imprinted UBE3A, which encodes an E3 ubiquitin ligase. Four mechanisms that render the maternally inherited UBE3A nonfunctional are recognized, the most common of which is deletion of the maternal chromosomal region 15q11-q13. Remarkably, duplication of the same chromosomal region is one of the few characterized persistent genetic abnormalities associated with autistic spectrum disorder, occurring in >1-2% of all cases of autism spectrum disorder. While the overall morphology of the brain and connectivity of neural projections appear largely normal in AS mouse models, major functional defects are detected at the level of context-dependent learning, as well as impaired maturation of hippocampal and neocortical circuits. While these findings demonstrate a crucial role for ubiquitin protein ligase E3A in synaptic development, the mechanisms by which deficiency of ubiquitin protein ligase E3A leads to AS pathophysiology in humans remain poorly understood. However, recent efforts have shown promise in restoring functions disrupted in AS mice, renewing hope that an effective treatment strategy can be found.
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Affiliation(s)
- Seth S Margolis
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, 725 N. Wolfe St., Baltimore, MD, 21205, USA,
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9
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Shi SQ, Bichell TJ, Ihrie RA, Johnson CH. Ube3a imprinting impairs circadian robustness in Angelman syndrome models. Curr Biol 2015; 25:537-45. [PMID: 25660546 PMCID: PMC4348236 DOI: 10.1016/j.cub.2014.12.047] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/24/2014] [Accepted: 12/15/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND The paternal allele of Ube3a is silenced by imprinting in neurons, and Angelman syndrome (AS) is a disorder arising from a deletion or mutation of the maternal Ube3a allele, which thereby eliminates Ube3a neuronal expression. Sleep disorders such as short sleep duration and increased sleep onset latency are very common in AS. RESULTS We found a unique link between neuronal imprinting of Ube3a and circadian rhythms in two mouse models of AS, including enfeebled circadian activity behavior and slowed molecular rhythms in ex vivo brain tissues. As a consequence of compromised circadian behavior, metabolic homeostasis is also disrupted in AS mice. Unsilencing the paternal Ube3a allele restores functional circadian periodicity in neurons deficient in maternal Ube3a but does not affect periodicity in peripheral tissues that are not imprinted for uniparental Ube3a expression. The ubiquitin ligase encoded by Ube3a interacts with the central clock components BMAL1 and BMAL2. Moreover, inactivation of Ube3a expression elevates BMAL1 levels in brain regions that control circadian behavior of AS-model mice, indicating an important role for Ube3a in modulating BMAL1 turnover. CONCLUSIONS Ube3a expression constitutes a direct mechanistic connection between symptoms of a human neurological disorder and the central circadian clock mechanism. The lengthened circadian period leads to delayed phase, which could explain the short sleep duration and increased sleep onset latency of AS subjects. Moreover, we report the pharmacological rescue of an AS phenotype, in this case, altered circadian period. These findings reveal potential treatments for sleep disorders in AS patients.
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Affiliation(s)
- Shu-qun Shi
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
| | - Terry Jo Bichell
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37235, USA
| | - Rebecca A Ihrie
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37235, USA; Cancer Biology, Vanderbilt University, Nashville, TN 37235, USA
| | - Carl Hirschie Johnson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37235, USA; Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37235, USA.
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10
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Abstract
"Angelman syndrome" (AS) is a neurodevelopmental disorder whose main features are intellectual disability, lack of speech, seizures, and a characteristic behavioral profile. The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water. Microcephaly and subtle dysmorphic features, as well as ataxia and other movement disturbances, are additional features seen in most affected individuals. AS is due to deficient expression of the ubiquitin protein ligase E3A (UBE3A) gene, which displays paternal imprinting. There are four molecular classes of AS, and some genotype-phenotype correlations have emerged. Much remains to be understood regarding how insufficiency of E6-AP, the protein product of UBE3A, results in the observed neurodevelopmental deficits. Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling.
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Affiliation(s)
- Lynne M Bird
- Department of Pediatrics, University of California, Division of Genetics, Rady Children’s Hospital, San Diego, California, USA
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11
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Bai JL, Qu YJ, Jin YW, Wang H, Yang YL, Jiang YW, Yang XY, Zou LP, Song F. Molecular and clinical characterization of Angelman syndrome in Chinese patients. Clin Genet 2013; 85:273-7. [PMID: 23551092 DOI: 10.1111/cge.12155] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/27/2013] [Accepted: 03/27/2013] [Indexed: 01/11/2023]
Abstract
Angelman syndrome (AS) is a neurobehavioral disorder caused by lack of function of the maternal copy of the ubiquitin-protein ligase E3A (UBE3A) gene. In our study, 49 unrelated patients with classic AS phenotypes were confirmed by methylation-specific PCR (MS-PCR) analysis, short tandem repeat linkage analysis, and mutation screening of the UBE3A gene. Among the Chinese AS patients, 83.7% (41/49) had deletions on maternal chromosome 15q11.2-13. Paternal uniparental disomy, imprinting defects, and UBE3A gene mutations each accounted for 4.1% (2/49). Two AS patients were confirmed by MS-PCR analysis, but the pathogenic mechanism was unknown because their parents' samples were unavailable. Of the two described UBE3A gene mutations, that is, p.Pro400His (c.1199C>A) and p.Asp563Gly (c.1688A>G), the latter has not been reported previously. Mutation transmission analysis showed that the p.Pro400His and p.Asp563Gly mutations originated from asymptomatic mothers. The patients with the maternal deletion showed AS clinical manifestations that were consistent with other studies. However, the incidence of microcephaly (36.7%, 11/30) was lower than that in the Caucasian population (approximately 80%), but similar to that of the Japanese population (34.5%). Our study demonstrated that the occurrence of microcephaly in AS may vary among different populations.
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Affiliation(s)
- J-L Bai
- Department of Medical Genetics, Capital Institute of Pediatrics, Beijing, 100020, China
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12
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Askree SH, Dharamrup S, Hjelm LN, Coffee B. Parent-of-Origin Testing for 15q11-q13 Gains by Quantitative DNA Methylation Analysis. J Mol Diagn 2012; 14:192-8. [DOI: 10.1016/j.jmoldx.2012.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 01/10/2012] [Accepted: 01/30/2012] [Indexed: 10/28/2022] Open
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Gustin RM, Bichell TJ, Bubser M, Daily J, Filonova I, Mrelashvili D, Deutch AY, Colbran RJ, Weeber EJ, Haas KF. Tissue-specific variation of Ube3a protein expression in rodents and in a mouse model of Angelman syndrome. Neurobiol Dis 2010; 39:283-91. [PMID: 20423730 DOI: 10.1016/j.nbd.2010.04.012] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 04/16/2010] [Accepted: 04/18/2010] [Indexed: 12/13/2022] Open
Abstract
Angelman syndrome (AS) is a neurogenetic disorder caused by loss of maternal UBE3A expression or mutation-induced dysfunction of its protein product, the E3 ubiquitin-protein ligase, UBE3A. In humans and rodents, UBE3A/Ube3a transcript is maternally imprinted in several brain regions, but the distribution of native UBE3A/Ube3a(1) protein expression has not been comprehensively examined. To address this, we systematically evaluated Ube3a expression in the brain and peripheral tissues of wild-type (WT) and Ube3a maternal knockout mice (AS mice). Immunoblot and immunohistochemical analyses revealed a marked loss of Ube3a protein in hippocampus, hypothalamus, olfactory bulb, cerebral cortex, striatum, thalamus, midbrain, and cerebellum in AS mice relative to WT littermates. Also, Ube3a expression in heart and liver of AS mice showed greater than the predicted 50% reduction relative to WT mice. Co-localization studies showed Ube3a expression to be primarily neuronal in all brain regions and present in GABAergic interneurons as well as principal neurons. These findings suggest that neuronal function throughout the brain is compromised in AS.
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Affiliation(s)
- Richard M Gustin
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
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Abstract
The ubiquitin ligase E6-AP (E6-associated protein) represents a prime example for the notion that deregulated modification of proteins with ubiquitin contributes to the development of human disease: loss of E6-AP function by mutation is responsible for the development of AS (Angelman syndrome), a neurological disorder, and unscheduled activation of E6-AP by complex formation with the E6 oncoprotein of HPVs (human papillomaviruses) contributes to cervical carcinogenesis. However, while there is a considerable amount of data concerning the oncogenic properties of the E6–E6-AP complex, only little is known about the function(s) of E6-AP in neurons. This is mainly due to the fact that although some E6-AP substrates have been identified, it is at present unclear whether deregulated modification/degradation of these proteins is involved in the pathogenesis of AS. Similarly, the cellular pathways involving E6-AP remain enigmatic. To obtain insights into the physiological functions of E6-AP, we are currently employing several strategies, including quantitative affinity proteomics and RNA interference approaches. The results obtained will eventually allow the introduction of E6-AP into functional protein networks and so reveal potential targets for molecular approaches in the treatment of E6-AP-associated diseases.
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15
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Takano K, Okajima M, Saitoh S. DNA demethylation reactivation of imprinted genes in cell lines from patients with Prader-Willi syndrome and a mouse model. Am J Med Genet A 2008; 143A:1386-90. [PMID: 17506103 DOI: 10.1002/ajmg.a.31765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Kyoko Takano
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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16
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Saitoh S, Hosoki K, Takano K, Tonoki H. Mosaic paternally derived inv dup(15) may partially rescue the Prader-Willi syndrome phenotype with uniparental disomy. Clin Genet 2007; 72:378-80. [PMID: 17850637 DOI: 10.1111/j.1399-0004.2007.00860.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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17
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Shai A, Brake T, Somoza C, Lambert PF. The human papillomavirus E6 oncogene dysregulates the cell cycle and contributes to cervical carcinogenesis through two independent activities. Cancer Res 2007; 67:1626-35. [PMID: 17308103 PMCID: PMC2859178 DOI: 10.1158/0008-5472.can-06-3344] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cervical cancer is a leading cause of death due to cancer among women worldwide. Using transgenic mice to dissect the contributions of the human papillomavirus (HPV) 16 E6 and E7 oncogenes in cervical cancer, E7 was identified previously to be the dominant oncogene. Specifically, when treated with exogenous estrogen for 6 months, E7 transgenic mice developed cancer throughout the reproductive tract, but E6 transgenic mice did not. E6 contributed to carcinogenesis of the reproductive tract, as E6/E7 double transgenic mice treated for 6 months with estrogen developed larger cancers than E7 transgenic mice. In the current study, we investigated whether the E6 oncogene alone could cooperate with estrogen to induce cervical cancer after an extended estrogen treatment period of 9 months. We found that the E6 oncogene synergizes with estrogen to induce cervical cancer after 9 months, indicating that E6 has a weaker but detectable oncogenic potential in the reproductive tract compared with the E7 oncogene. Using transgenic mice that express mutant forms of HPV16 E6, we determined that the interactions of E6 with cellular alpha-helix and PDZ partners correlate with its ability to induce cervical carcinogenesis. In analyzing the tumors arising in E6 transgenic mice, we learned that E6 induces expression of the E2F-responsive genes, Mcm7 and cyclin E, in the absence of the E7 oncogene. E6 also prevented the expression of p16 in tumors of the reproductive tract through a mechanism mediated by the interaction of E6 with alpha-helix partners.
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Affiliation(s)
- Anny Shai
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Tiffany Brake
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | | | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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Shai A, Nguyen ML, Wagstaff J, Jiang YH, Lambert PF. HPV16 E6 confers p53-dependent and p53-independent phenotypes in the epidermis of mice deficient for E6AP. Oncogene 2006; 26:3321-8. [PMID: 17130828 PMCID: PMC2858288 DOI: 10.1038/sj.onc.1210130] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
High-risk human papillomaviruses are the causative agents of cervical and other anogenital cancers. In these cancers, two viral oncogenes, E6 and E7, are expressed. E6 is best known for its ability to inactivate the tumor suppressor p53, which is thought to arise through ubiquitin-mediated degradation of p53 and involve a ternary complex between E6, p53 and the E3 ligase, E6AP. In mice transgenic for wild-type HPV16 E6, its expression leads to epithelial hyperplasia and an abrogation of normal cellular responses to DNA damage. Whereas only the latter phenotype is dependent upon E6's inactivation of p53, both are reduced in transgenic mice expressing an E6 mutant severely reduced in its binding to E6AP and other cellular proteins that bind E6 through a shared alpha-helix motif. Here, we investigated whether E6AP is required for the induction of the above phenotypes through the use of both E6AP-mutant and E6AP-null mice. E6, in the absence of E6AP retains an ability to induce epithelial hyperplasia, abrogate DNA damage responses and inhibit the induction of p53 protein following exposure to ionizing radiation. We conclude that E6 is able to induce both p53-dependent and p53-independent phenotypes through E6AP-independent pathways in the mouse.
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Affiliation(s)
- A Shai
- Department of Cancer Biology, McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - ML Nguyen
- Department of Cancer Biology, McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - J Wagstaff
- Department of Pediatrics, Carolinas Medical Center, Charlotte, NC, USA
| | - Y-h Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Baylor University, Houston, TX, USA
| | - PF Lambert
- Department of Cancer Biology, McArdle Laboratory for Cancer Research, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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19
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Schüle B, Albalwi M, Northrop E, Francis DI, Rowell M, Slater HR, Gardner RJM, Francke U. Molecular breakpoint cloning and gene expression studies of a novel translocation t(4;15)(q27;q11.2) associated with Prader-Willi syndrome. BMC MEDICAL GENETICS 2005; 6:18. [PMID: 15877813 PMCID: PMC1142316 DOI: 10.1186/1471-2350-6-18] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Accepted: 05/06/2005] [Indexed: 11/10/2022]
Abstract
BACKGROUND Prader-Willi syndrome (MIM #176270; PWS) is caused by lack of the paternally-derived copies, or their expression, of multiple genes in a 4 Mb region on chromosome 15q11.2. Known mechanisms include large deletions, maternal uniparental disomy or mutations involving the imprinting center. De novo balanced reciprocal translocations in 5 reported individuals had breakpoints clustering in SNRPN intron 2 or exon 20/intron 20. To further dissect the PWS phenotype and define the minimal critical region for PWS features, we have studied a 22 year old male with a milder PWS phenotype and a de novo translocation t(4;15)(q27;q11.2). METHODS We used metaphase FISH to narrow the breakpoint region and molecular analyses to map the breakpoints on both chromosomes at the nucleotide level. The expression of genes on chromosome 15 on both sides of the breakpoint was determined by RT-PCR analyses. RESULTS Pertinent clinical features include neonatal hypotonia with feeding difficulties, hypogonadism, short stature, late-onset obesity, learning difficulties, abnormal social behavior and marked tolerance to pain, as well as sticky saliva and narcolepsy. Relative macrocephaly and facial features are not typical for PWS. The translocation breakpoints were identified within SNRPN intron 17 and intron 10 of a spliced non-coding transcript in band 4q27. LINE and SINE sequences at the exchange points may have contributed to the translocation event. By RT-PCR of lymphoblasts and fibroblasts, we find that upstream SNURF/SNRPN exons and snoRNAs HBII-437 and HBII-13 are expressed, but the downstream snoRNAs PWCR1/HBII-85 and HBII-438A/B snoRNAs are not. CONCLUSION As part of the PWCR1/HBII-85 snoRNA cluster is highly conserved between human and mice, while no copy of HBII-438 has been found in mouse, we conclude that PWCR1/HBII-85 snoRNAs is likely to play a major role in the PWS- phenotype.
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MESH Headings
- Adult
- Antigens, Neoplasm
- Autoantigens
- Blotting, Southern/methods
- Chromosome Breakage/genetics
- Chromosome Mapping/methods
- Chromosomes, Human, Pair 15/genetics
- Chromosomes, Human, Pair 4/genetics
- Cloning, Molecular/methods
- Cytogenetic Analysis/methods
- DNA Methylation
- Expressed Sequence Tags
- Gene Expression Regulation/genetics
- Humans
- Introns/genetics
- Male
- Nerve Tissue Proteins/genetics
- Nuclear Proteins/genetics
- Nucleotides/genetics
- Phenotype
- Prader-Willi Syndrome/genetics
- Proteins/genetics
- RNA, Small Nucleolar/genetics
- Ribonucleoproteins/genetics
- Ribonucleoproteins, Small Nuclear/genetics
- Translocation, Genetic/genetics
- Ubiquitin-Protein Ligases
- snRNP Core Proteins
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Affiliation(s)
- Birgitt Schüle
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Mohammed Albalwi
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
- Department of Pathology, King Fahad National Guard Hospital, Riyadh 11426, Saudi Arabia
| | - Emma Northrop
- Murdoch Children's Research Institute and Paediatrics Department, University of Melbourne, Royal Children's Hospital, Parkville 3052, Victoria, Australia
| | - David I Francis
- Murdoch Children's Research Institute and Paediatrics Department, University of Melbourne, Royal Children's Hospital, Parkville 3052, Victoria, Australia
| | - Margaret Rowell
- Department of Child Development and Rehabilitation, Royal Children's Hospital, Parkville 3052, Victoria, Australia
| | - Howard R Slater
- Murdoch Children's Research Institute and Paediatrics Department, University of Melbourne, Royal Children's Hospital, Parkville 3052, Victoria, Australia
| | - RJ McKinlay Gardner
- Murdoch Children's Research Institute and Paediatrics Department, University of Melbourne, Royal Children's Hospital, Parkville 3052, Victoria, Australia
| | - Uta Francke
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
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20
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Girardet A, Moncla A, Hamamah S, Claustres M. Strategies for preimplantation genetic diagnosis of Angelman syndrome caused by mutations in the UBE3A gene. Reprod Biomed Online 2005; 10:519-26. [PMID: 15901461 DOI: 10.1016/s1472-6483(10)60830-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Angelman syndrome (AS) is a neurodevelopmental disorder associated with the loss of maternal gene expression in chromosome region 15q11-q13. AS is caused by a wide variety of genetic mechanisms, including mutations in the UBE3A gene that have been identified in 10-15% of patients; when the mother is heterozygous for the causative mutation, the risk of recurrence in subsequent pregnancies is 50%. The present authors have developed a preimplantation genetic diagnosis (PGD) assay for a family displaying a 10 bp deletion in exon 9 of the UBE3A gene, which was shared by two affected children and their phenotypically normal mother. A duplex polymerase chain reaction protocol was established, allowing the efficient amplification of the mutation together with an informative microsatellite marker (D15S122) located in intron 1 of the UBE3A gene. As most of UBE3A mutations identified so far are unique to one family, the present authors have also developed an indirect single cell protocol based upon the co-amplification of two microsatellite markers located within (D15S122) and close to the UBE3A gene (D15S1506). This strategy may be applied to all informative families requesting PGD for Angelman syndrome associated with mutations in the UBE3A gene.
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Affiliation(s)
- A Girardet
- Laboratoire de Génétique Moléculaire, Centre Hospitalo-Universitaire (CHU) and Institut Universitaire de Recherche Clinique (IURC), 641 Avenue du Doyen Gaston Giraud, 34093 Montpellier cedex 5, France.
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21
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Kashiwagi A, Meguro M, Hoshiya H, Haruta M, Ishino F, Shibahara T, Oshimura M. Predominant maternal expression of the mouse Atp10c in hippocampus and olfactory bulb. J Hum Genet 2003; 48:194-8. [PMID: 12730723 DOI: 10.1007/s10038-003-0009-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2002] [Accepted: 02/09/2003] [Indexed: 10/26/2022]
Abstract
The human chromosome 15q11-q13 region is one of the most intriguing imprinted domains, and the abnormalities inherited are associated with neurological disorders including Prader-Willi syndrome (PWS), Angelman syndrome (AS) and autism. Recently we have identified a novel maternally expressed gene, ATP10C, that encodes a putative aminophospholipid translocase within this critical region, 200 kb distal to UBE3A in an imprinted domain on human chromosome 15. ATP10C, with UBE3A, displayed tissue-specific imprinting with predominant expression of the maternal allele in the brain. In this study, we demonstrated that the mouse homologue, Atp10c/pfatp, showed tissue-specific maternal expression in the hippocampus and olfactory bulb, which overlapped the region of imprinted Ube3a expression. These data suggest that the imprinted transcript of Atp10c in the specific region of CNS may be associated with neurological disorders including AS and autism.
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Affiliation(s)
- Akiko Kashiwagi
- Division of Molecular and Cell Genetics, Department of Molecular and Cellular Biology, School of Life Sciences, Faculty of Medicine, Tottori University, 86 Nishimachi, Yonago 683-8503, Japan
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22
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Sinkkonen ST, Homanics GE, Korpi ER. Mouse models of Angelman syndrome, a neurodevelopmental disorder, display different brain regional GABA(A) receptor alterations. Neurosci Lett 2003; 340:205-8. [PMID: 12672542 DOI: 10.1016/s0304-3940(03)00123-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Angelman syndrome is a severe neurodevelopmental disorder with cognitive impairment and neurological deficits. It results from a maternal deletion of human chromosome 15q11-13 containing two candidate genes E6-P ubiquitin-protein ligase (UBE3A) and GABA(A) receptor beta3 subunit (GABRB3), the latter of which has been also linked to autism. To clarify the potential role of GABA(A) beta3 subunit-containing inhibitory receptors in these disorders, we applied ligand autoradiography on brain sections from mice with inactivated GABRB3 or maternal UBE3A genes. Binding of GABA(A) receptor channel ([(35)S]t-butylbicyclophosphorothionate) and benzodiazepine ([(3)H]Ro 15-4513) site ligands was reduced in selected brain regions of the beta3-deficient mice as compared to controls, while the UBE3A-deficient mice failed to show reduced GABA(A) receptors. The results, suggesting two different pathophysiological mechanisms, are in agreement with positron emission tomography results from Angelman syndrome patients of the corresponding genetic backgrounds.
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Affiliation(s)
- S T Sinkkonen
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Turku, Finland
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23
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Davies HD, Leusink GL, McConnell A, Deyell M, Cassidy SB, Fick GH, Coppes MJ. Myeloid leukemia in Prader-Willi syndrome. J Pediatr 2003; 142:174-8. [PMID: 12584540 DOI: 10.1067/mpd.2003.81] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE To evaluate the frequency of cancers recorded by the Surveillance, Epidemiology, and End Results (SEER) Program in persons with Prader-Willi syndrome (PWS) METHODS: A survey was mailed in 1994 to 1852 registrants of the PWS Association (USA) inquiring about a diagnosis of any type of benign tumor or cancer (malignant tumor or leukemia). The risk of developing cancer was then estimated by comparing the observed number of cancers in the PWS population during 1975 to 1994 to the expected number in the general US population using data from the 1971-1994 SEER Cancer Statistics Review. RESULTS Of the 1852 persons, 1160 (63%) responded, or 75% (1160/1552) of those who received the survey. The total number of observed cancer cases in the PWS study population was 8 versus 4.80 expected in the general US population (P =.1610). Three cases of myeloid leukemia were observed versus 0.075 leukemias expected (P =.0001). CONCLUSIONS There appears to be an increased risk of myeloid leukemias, but not other cancers, among persons with PWS.
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Affiliation(s)
- H Dele Davies
- Departments of Pediatrics and Oncology, University of Calgary, Alberta Children's Hospital, Calgary, Alberta, Canada
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24
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Matin MM, Baumer A, Hornby DP. An analytical method for the detection of methylation differences at specific chromosomal loci using primer extension and ion pair reverse phase HPLC. Hum Mutat 2002; 20:305-11. [PMID: 12325026 DOI: 10.1002/humu.10118] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We have developed a rapid, accurate, and quantitative method for the detection of methylation differences at specific CpG sites based on bisulfite treatment of DNA followed by primer extension and ion-pair reversed-phase high performance liquid chromatography (IP RP HPLC). The application of the method is illustrated by analysis of differentially imprinted alleles arising from Prader-Willi and Angelman syndromes. In order to convert unmethylated cytosines to uracil, plasmid and genomic DNA samples were treated with sodium bisulfite and the targeted sequence was then amplified using oligodeoxynucleotide primers specific for the bisulfite-deaminated DNA. The PCR product(s) from this step was used as a template for a primer extension reaction and the products were subsequently analyzed chromatographically using IP RP HPLC. This method eliminates the need to use restriction enzymes to determine the methylation status of the amplicon and circumvents the need for radio labeling for the quantitative measurements. Finally, this method removes the need for nucleotide sequencing because it is not solely reliant on the presence or absence of one or more PCR products, as is the case with related methods.
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Affiliation(s)
- Maryam M Matin
- Transgenomic Research Laboratory, Krebs Institute, Department of Molecular Biology, Western Bank, Sheffield, UK
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25
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Bürger J, Horn D, Tönnies H, Neitzel H, Reis A. Familial interstitial 570 kbp deletion of the UBE3A gene region causing Angelman syndrome but not Prader-Willi syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 111:233-7. [PMID: 12210318 DOI: 10.1002/ajmg.10498] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Angelman syndrome (AS) is a disorder of psychomotor development caused by loss of function of the imprinted UBE3A gene. Since the paternal UBE3A copy is regularly silent, only mutations inactivating the maternal copy cause AS. Among 1,272 patients suspected of AS, we found one with an isolated deletion of the UBE3A gene on the maternally inherited chromosome. Initial DNA methylation testing at the SNURF-SNRPN locus in the patient revealed a normal pattern. The deletion was only detected through allelic loss at microsatellite loci D15S1506, D15S122, and D15S210, and confirmed with fluorescence in situ hybridization (FISH) using bacterial artificial chromosome (BAC) probes derived from the loci. It extends approximately 570 kilobase pairs (kbp), encompassing the UBE3A locus, and is flanked by loci PAR/SN and D15S986. The deletion is familial, and haplotype studies suggest that a great grandfather of the index patient already carried this deletion, and that it causes AS when inherited through the female germline but not Prader-Willi syndrome (PWS) when paternally inherited. Our findings support the hypothesis that the functional loss of maternal UBE3A gene activity is sufficient to cause AS and that the deleted region does not contain genes or other structures that are involved in PWS. Finally, this case highlights that methylation tests can fail to detect some familial AS cases with a recurrence risk of 50%.
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Affiliation(s)
- Joachim Bürger
- Institute of Human Genetics, Charité, Humboldt-Universität, Berlin, Germany
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26
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Smith CL, DeVera DG, Lamb DJ, Nawaz Z, Jiang YH, Beaudet AL, O'Malley BW. Genetic ablation of the steroid receptor coactivator-ubiquitin ligase, E6-AP, results in tissue-selective steroid hormone resistance and defects in reproduction. Mol Cell Biol 2002; 22:525-35. [PMID: 11756548 PMCID: PMC139730 DOI: 10.1128/mcb.22.2.525-535.2002] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2001] [Revised: 06/06/2001] [Accepted: 10/05/2001] [Indexed: 11/20/2022] Open
Abstract
The E6-associated protein (E6-AP), although originally identified as a ubiquitin ligase, has recently been shown to function as a coactivator of steroid receptor-dependent gene expression in in vitro assays. In order to determine whether E6-AP acts as a coactivator in vivo, physiological parameters associated with male and female sex steroid action were assessed in the E6-AP null mouse. Gonadal size was reduced in E6-AP null male and female mice in comparison to wild-type controls in conjunction with reduced fertility in both genders. Consistent with this observation, defects in sperm production and function, as well as ovulation were observed. In comparison to wild-type controls, induction of prostate gland growth induced by testosterone and uterine growth by estradiol were significantly reduced. In contrast, estrogen and progesterone-stimulated growth of virgin mammary gland was not compromised by E6-AP ablation despite E6-AP expression in this tissue. This latter finding contrasts with the impaired estrogen and progesterone-induced mammary gland development observed previously for steroid receptor coactivator type 1 (SRC-1) and SRC-3 female knockout mice. Taken together, these results are consistent with a role for E6-AP in mediating a subset of steroid hormone actions in vivo. Nevertheless, differences observed between SRC and E6-AP knockout phenotypes indicate that these two families of steroid receptor coactivators are not functionally equivalent and supports the hypothesis that coactivators contribute to tissue-specific steroid hormone action.
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Affiliation(s)
- Carolyn L Smith
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030-3498, USA.
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27
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Lossie AC, Whitney MM, Amidon D, Dong HJ, Chen P, Theriaque D, Hutson A, Nicholls RD, Zori RT, Williams CA, Driscoll DJ. Distinct phenotypes distinguish the molecular classes of Angelman syndrome. J Med Genet 2001; 38:834-45. [PMID: 11748306 PMCID: PMC1734773 DOI: 10.1136/jmg.38.12.834] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Angelman syndrome (AS) is a severe neurobehavioural disorder caused by defects in the maternally derived imprinted domain located on 15q11-q13. Most patients acquire AS by one of five mechanisms: (1) a large interstitial deletion of 15q11-q13; (2) paternal uniparental disomy (UPD) of chromosome 15; (3) an imprinting defect (ID); (4) a mutation in the E3 ubiquitin protein ligase gene (UBE3A); or (5) unidentified mechanism(s). All classical patients from these classes exhibit four cardinal features, including severe developmental delay and/or mental retardation, profound speech impairment, a movement and balance disorder, and AS specific behaviour typified by an easily excitable personality with an inappropriately happy affect. In addition, patients can display other characteristics, including microcephaly, hypopigmentation, and seizures. METHODS We restricted the present study to 104 patients (93 families) with a classical AS phenotype. All of our patients were evaluated for 22 clinical variables including growth parameters, acquisition of motor skills, and history of seizures. In addition, molecular and cytogenetic analyses were used to assign a molecular class (I-V) to each patient for genotype-phenotype correlations. RESULTS In our patient repository, 22% of our families had normal DNA methylation analyses along 15q11-q13. Of these, 44% of sporadic patients had mutations within UBE3A, the largest percentage found to date. Our data indicate that the five molecular classes can be divided into four phenotypic groups: deletions, UPD and ID patients, UBE3A mutation patients, and subjects with unknown aetiology. Deletion patients are the most severely affected, while UPD and ID patients are the least. Differences in body mass index, head circumference, and seizure activity are the most pronounced among the classes. CONCLUSIONS Clinically, we were unable to distinguish between UPD and ID patients, suggesting that 15q11-q13 contains the only significant maternally expressed imprinted genes on chromosome 15.
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Affiliation(s)
- A C Lossie
- R C Philips Unit and Division of Genetics, Department of Pediatrics, University of Florida, Gainesville, FL 32610-0296, USA
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28
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Sakatani T, Wei M, Katoh M, Okita C, Wada D, Mitsuya K, Meguro M, Ikeguchi M, Ito H, Tycko B, Oshimura M. Epigenetic heterogeneity at imprinted loci in normal populations. Biochem Biophys Res Commun 2001; 283:1124-30. [PMID: 11355889 DOI: 10.1006/bbrc.2001.4916] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Genomic imprinting is the phenomenon by which the two alleles of certain genes are differentially expressed according to their parental origin. Extensive analysis of allelic expression at multiple imprinted loci in a normal population has not performed so far. In the present study, we examined the allelic expression pattern of three imprinted genes in a panel of 262 Japanese normal individuals. We observed differences in the extent of maintenance of allele-specific expression of the three genes. The allelic expression of small nuclear ribonucleoprotein N (SNRPN) was stringently regulated while that of multimembrane-spanning polyspecific transporter-like gene 1 (IMPT1) showed a large degree of variation. Significant biallelic expression of insulin-like growth factor II (IGF2) was observed in about 10% of normal individuals. Our findings add to the accumulating evidence for variable allelic expression at multiple loci in a normal human population. This epigenetic heterogeneity can be a stable trait and potentially influence individual phenotypes.
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Affiliation(s)
- T Sakatani
- CREST Program of the Japan Science and Technology Corporation (JST), Tottori University, Yonago, Japan
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29
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Fridman C, Koiffmann CP. Genomic imprinting: genetic mechanisms and phenotypic consequences in Prader-Willi and Angelman syndromes. Genet Mol Biol 2000. [DOI: 10.1590/s1415-47572000000400004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Chromosomal 15q11-q13 region is of great interest in Human Genetics because many structural rearrangements have been described for it (deletions, duplications and translocations) leading to phenotypes resulting in conditions such as the Prader-Willi (PWS) and Angelman (AS) syndromes which were the first human diseases found to be related to the differential expression of parental alleles (genomic imprinting). Contrary to Mendelian laws where the parental inheritance of genetic information does not influence gene expression, genomic imprinting is characterized by DNA modifications that produce different phenotypes depending on the parental origin of the mutation. Clinical manifestation of PWS appears when the loss of paternally expressed genes occurs and AS results from the loss of a maternally expressed gene. Different genetic mechanisms can lead to PWS or AS, such as deletions, uniparental disomy or imprinting mutation. In AS patients an additional class occurs with mutations on the UBE3A gene. Studies of PWS and AS patients can help us to understand the imprinting process, so that other genomic regions with similar characteristics can be located, and different syndromes can have their genetic mechanisms elucidated.
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30
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Pfeifer K. Mechanisms of genomic imprinting. Am J Hum Genet 2000; 67:777-87. [PMID: 10986038 PMCID: PMC1287882 DOI: 10.1086/303101] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2000] [Accepted: 08/17/2000] [Indexed: 12/12/2022] Open
Abstract
Imprinted genes represent a curious defiance of normal Mendelian genetics. Mammals inherit two complete sets of chromosomes, one from the mother and one from the father, and most autosomal genes will be expressed from both the maternal and the paternal alleles. Imprinted genes, however, are expressed from only one chromosome, in a parent-of-origin-dependent manner. Because silent and active promoters are present in a single nucleus, the differences in activity cannot be explained by transcription-factor abundance. Thus, transcription of imprinted genes represents a clear situation in which epigenetic mechanisms restrict gene expression and, therefore, offers a model for understanding the role of DNA modifications and chromatin structure in maintaining appropriate patterns of expression. Furthermore, because of their parent-of-origin-restricted expression, phenotypes determined by imprinted genes are susceptible not only to genetic alterations in the genes but also to disruptions in the epigenetic programs controlling regulation. Imprinted genes are often associated with human diseases, including disorders affecting cell growth, development, and behavior.
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Affiliation(s)
- K Pfeifer
- Laboratory of Mammalian Genes and Development, NICHD/NIH, Bethesda, MD 20892, USA.
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Abstract
Genomic imprinting is an epigenetic process by which the male and the female germline of viviparous taxa confer a sex-specific mark (imprint) on certain chromosomal regions. The imprint is reset in the germline of each generation, inherited through somatic cell divisions during postzygotic development and used to regulate parent-of-origin specific expression of susceptible genes. Aberrant imprinting leading to aberrant gene expression patterns represents a novel class of mutations and was first identified in patients with Angelman syndrome and Prader-Willi syndrome. The finding of inherited cis-acting mutations in some of these cases has led to the identification of an imprinting center, which is involved in resetting of the imprint during gametogenesis. Other mutations may interfere with the somatic inheritance of the imprint during postzygotic development.
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Affiliation(s)
- B Horsthemke
- Institut für Humangenetik, Universitätsklinikum, Essen, Germany
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32
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Saitoh S, Wada T. Parent-of-origin specific histone acetylation and reactivation of a key imprinted gene locus in Prader-Willi syndrome. Am J Hum Genet 2000; 66:1958-62. [PMID: 10775525 PMCID: PMC1378035 DOI: 10.1086/302917] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2000] [Accepted: 04/05/2000] [Indexed: 11/03/2022] Open
Abstract
To examine the chromatin basis of imprinting in chromosome 15q11-q13, we have investigated the status of histone acetylation of the SNURF-SNRPN locus, which is a key imprinted gene locus in Prader-Willi syndrome (PWS). Chromatin immunoprecipitation (ChIP) studies revealed that the unmethylated CpG island of the active, paternally derived allele of SNURF-SNRPN was associated with acetylated histones, whereas the methylated maternally derived, inactive allele was specifically hypoacetylated. The body of the SNURF-SNRPN gene was associated with acetylated histones on both alleles. Furthermore, treatment of PWS cells with the DNA methyltransferase inhibitor 5-azadeoxycytidine (5-aza-dC) induced demethylation of the SNURF-SNRPN CpG island and restoration of gene expression on the maternal allele. The reactivation was associated with increased H4 acetylation but not with H3 acetylation at the SNURF-SNRPN CpG island. These findings indicate that (1) a significant role for histone deacetylation in gene silencing is associated with imprinting in 15q11-q13 and (2) silenced genes in PWS can be reactivated by drug treatment.
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Affiliation(s)
- S Saitoh
- Department of Pediatrics, Hokkaido University School of Medicine, Sapporo 060-8638, Japan.
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Glenn CC, Deng G, Michaelis RC, Tarleton J, Phelan MC, Surh L, Yang TP, Driscoll DJ. DNA methylation analysis with respect to prenatal diagnosis of the Angelman and Prader-Willi syndromes and imprinting. Prenat Diagn 2000. [DOI: 10.1002/(sici)1097-0223(200004)20:4<300::aid-pd803>3.0.co;2-a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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34
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Lee S, Wevrick R. Identification of novel imprinted transcripts in the Prader-Willi syndrome and Angelman syndrome deletion region: further evidence for regional imprinting control. Am J Hum Genet 2000; 66:848-58. [PMID: 10712201 PMCID: PMC1288168 DOI: 10.1086/302817] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Deletions and other abnormalities of human chromosome 15q11-q13 are associated with two developmental disorders, Prader-Willi syndrome (PWS) and Angelman syndrome (AS). Loss of expression of imprinted, paternally expressed genes has been implicated in PWS. However, the number of imprinted genes that contribute to PWS, and the range over which the imprinting signal acts to silence one copy of the gene in a parent-of-origin-specific manner, are unknown. To identify additional imprinted genes that could contribute to the PWS phenotype and to understand the regional control of imprinting in 15q11-q13, we have constructed an imprinted transcript map of the PWS-AS deletion interval. The imprinting status of 22 expressed sequence tags derived from the radiation-hybrid human transcript maps or physical maps was determined in a reverse transcriptase-PCR assay and correlated with the position of the transcripts on the physical map. Seven new paternally expressed transcripts localize to an approximately 1.5-Mb domain surrounding the SNRPN-associated imprinting center, which already includes four imprinted, paternally expressed genes. All other tested new transcripts in the deletion region were expressed from both alleles. A domain of exclusive paternal expression surrounding the imprinting center suggests strong regional control of the imprinting process. This study provides the means for further investigation of additional genes that cause or modify the phenotypes associated with rearrangements of 15q11-q13.
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Affiliation(s)
- S Lee
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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35
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Saitoh S, Buiting K, Cassidy SB, Conroy JM, Driscoll DJ, Gabriel JM, Gillessen-Kaesbach G, Glenn CC, Greenswag LR, Horsthemke B, Kondo I, Kuwajima K, Niikawa N, Rogan PK, Schwartz S, Seip J, Williams CA, Nicholls RD. Clinical spectrum and molecular diagnosis of Angelman and Prader-Willi syndrome patients with an imprinting mutation. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19970120)68:2<195::aid-ajmg15>3.0.co;2-p] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Jiang YH, Armstrong D, Albrecht U, Atkins CM, Noebels JL, Eichele G, Sweatt JD, Beaudet AL. Mutation of the Angelman ubiquitin ligase in mice causes increased cytoplasmic p53 and deficits of contextual learning and long-term potentiation. Neuron 1998; 21:799-811. [PMID: 9808466 DOI: 10.1016/s0896-6273(00)80596-6] [Citation(s) in RCA: 634] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The E6-AP ubiquitin ligase (human/mouse gene UBE3A/Ube3a) promotes the degradation of p53 in association with papilloma E6 protein, and maternal deficiency causes human Angelman syndrome (AS). Ube3a is imprinted with silencing of the paternal allele in hippocampus and cerebellum in mice. We found that the phenotype of mice with maternal deficiency (m-/p+) for Ube3a resembles human AS with motor dysfunction, inducible seizures, and a context-dependent learning deficit. Long-term potentiation (LTP) was severely impaired in m-/p+ mice despite normal baseline synaptic transmission and neuroanatomy, indicating that ubiquitination may play a role in mammalian LTP and that LTP may be abnormal in AS. The cytoplasmic abundance of p53 was increased in postmitotic neurons in m-/p+ mice and in AS, providing a potential biochemical basis for the phenotype through failure to ubiquitinate and degrade various effectors.
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Affiliation(s)
- Y H Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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37
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Abstract
Cervical carcinomas develop as a result of multiple genetic alterations. As the genetic alterations are the cause of malignant transformation, it is likely that specific genetic alterations lead to specific clinical behaviour. The aim of this study was (i) to localise chromosome arms that harbour likely tumour-suppressor genes, by analysing loss of heterozygosity (LOH) and (ii) to study the association of LOH with clinicopathological parameters. To define the regions of interest, we studied the presence of loss of heterozygosity at all chromosomes in 67 cervical carcinomas (stages IB and IIA) with 81 polymorphic markers. In addition, all frequent allelic imbalances were correlated with HPV status and clinicopathologic parameters including survival, FIGO-stage, lymph-node metastasis, tumour size, number of mitoses, vaso-invasion and histologic type. LOH at a frequency over 25% was observed at sites on 9 chromosome arms: 3p21, 4p16.1-15, 6p, 6q22.3-23.1, 11q22-24, 15q11-21.1, 17p13.3, 18q22-qter and Xq. LOH of chromosome 6q14-16.2, 6p22 and 17p13 correlated marginally with HPV-16 positivity. LOH on chromosome 3p21 was weakly correlated with high mitotic activity, while LOH on chromosomes 11q23.3, 15q21.1 and 17p13 correlated with low mitotic activity. LOH at chromosome 17p13 associated marginally with FIGO stage I, while LOH at chromosome 15q associated weakly with FIGO stage II. When chromosome 18q showed LOH in the tumour, the patients had decreased survival (p = 0.024). We conclude that, in carcinoma of the uterine cervix, a novel tumour-suppressor gene may be present on chromosome 15q21 and that patients with LOH on chromosome 18q have relatively poor survival (p = 0.025).
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Affiliation(s)
- A M Kersemaekers
- Department of Pathology, Leiden University Medical Centre, The Netherlands.
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38
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Buiting K, Dittrich B, Gross S, Lich C, Färber C, Buchholz T, Smith E, Reis A, Bürger J, Nöthen MM, Barth-Witte U, Janssen B, Abeliovich D, Lerer I, van den Ouweland AM, Halley DJ, Schrander-Stumpel C, Smeets H, Meinecke P, Malcolm S, Gardner A, Lalande M, Nicholls RD, Friend K, Schulze A, Matthijs G, Kokkonen H, Hilbert P, Van Maldergem L, Glover G, Carbonell P, Willems P, Gillessen-Kaesbach G, Horsthemke B. Sporadic imprinting defects in Prader-Willi syndrome and Angelman syndrome: implications for imprint-switch models, genetic counseling, and prenatal diagnosis. Am J Hum Genet 1998; 63:170-80. [PMID: 9634532 PMCID: PMC1377255 DOI: 10.1086/301935] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are caused by the loss of function of imprinted genes in proximal 15q. In approximately 2%-4% of patients, this loss of function is due to an imprinting defect. In some cases, the imprinting defect is the result of a parental imprint-switch failure caused by a microdeletion of the imprinting center (IC). Here we describe the molecular analysis of 13 PWS patients and 17 AS patients who have an imprinting defect but no IC deletion. Heteroduplex and partial sequence analysis did not reveal any point mutations of the known IC elements, either. Interestingly, all of these patients represent sporadic cases, and some share the paternal (PWS) or the maternal (AS) 15q11-q13 haplotype with an unaffected sib. In each of five PWS patients informative for the grandparental origin of the incorrectly imprinted chromosome region and four cases described elsewhere, the maternally imprinted paternal chromosome region was inherited from the paternal grandmother. This suggests that the grandmaternal imprint was not erased in the father's germ line. In seven informative AS patients reported here and in three previously reported patients, the paternally imprinted maternal chromosome region was inherited from either the maternal grandfather or the maternal grandmother. The latter finding is not compatible with an imprint-switch failure, but it suggests that a paternal imprint developed either in the maternal germ line or postzygotically. We conclude (1) that the incorrect imprint in non-IC-deletion cases is the result of a spontaneous prezygotic or postzygotic error, (2) that these cases have a low recurrence risk, and (3) that the paternal imprint may be the default imprint.
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Affiliation(s)
- K Buiting
- Institut für Humangenetik, Universitätsklinikum Essen, Essen, Germany
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39
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Malzac P, Webber H, Moncla A, Graham JM, Kukolich M, Williams C, Pagon RA, Ramsdell LA, Kishino T, Wagstaff J. Mutation analysis of UBE3A in Angelman syndrome patients. Am J Hum Genet 1998; 62:1353-60. [PMID: 9585605 PMCID: PMC1377156 DOI: 10.1086/301877] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Angelman syndrome (AS) is caused by chromosome 15q11-q13 deletions of maternal origin, by paternal uniparental disomy (UPD) 15, by imprinting defects, and by mutations in the UBE3A gene. UBE3A encodes a ubiquitin-protein ligase and shows brain-specific imprinting. Here we describe UBE3A coding-region mutations detected by SSCP analysis in 13 AS individuals or families. Two identical de novo 5-bp duplications in exon 16 were found. Among the other 11 unique mutations, 8 were small deletions or insertions predicted to cause frameshifts, 1 was a mutation to a stop codon, 1 was a missense mutation, and 1 was predicted to cause insertion of an isoleucine in the hect domain of the UBE3A protein, which functions in E2 binding and ubiquitin transfer. Eight of the cases were familial, and five were sporadic. In two familial cases and one sporadic case, mosaicism for UBE3A mutations was detected: in the mother of three AS sons, in the maternal grandfather of two AS first cousins, and in the mother of an AS daughter. The frequencies with which we detected mutations were 5 (14%) of 35 in sporadic cases and 8 (80%) of 10 in familial cases.
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Affiliation(s)
- P Malzac
- Departement de Genetique Medicale, Hopital d'Enfants de la Timone, Marseille, France
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40
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Abstract
Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are caused by deficiencies of gene expression from paternal or maternal chromosome 15q11-q13, respectively. Many advances have occurred during the past year. The gene for necdin was mapped in the PWS candidate region and found to be paternally expressed in mouse and human. The bisulfite method for analysis of methylation was established for genomic sequencing and diagnostics, and the methylation of Snrpn was studied in detail in the mouse. A region near the Snrpn promoter was shown to function as a silencer in Drosophila. Point mutations were found in the gene for E6-AP ubiquitin-protein ligase (UBE3A) identifying it as the AS gene, and tissue-specific imprinting (maternal expression) was shown in the human brain and in hippocampal neurons and Purkinje cells in the mouse.
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Affiliation(s)
- Y Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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41
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Francke U. Imprinted genes in the Prader-Willi deletion. NOVARTIS FOUNDATION SYMPOSIUM 1998; 214:264-75; discussion 275-9. [PMID: 9601023 DOI: 10.1002/9780470515501.ch16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Parent-of-origin-specific deletions of proximal chromosome 15q cause either the Prader-Willi syndrome (paternal deletion) or the Angelman syndrome (maternal deletion), two distinct neurodevelopmental disorders. In contrast to the Angelman syndrome, which can also be caused by mutations in a single gene (UBE3A, encoding a ubiquitin ligase), the Prader-Willi syndrome is caused by deletions in about two-thirds of cases and by maternal uniparental disomy in the remaining third. The consequence of both mechanisms, in addition to rare microdeletions or so-called 'imprinting mutations', is lack of the products of multiple genes in the region that are normally expressed only from the paternal chromosome. One gene that is consistently silent in the Prader-Willi syndrome is SNRPN, which encodes the small nuclear ribonucleoprotein particle-associated polypeptide N that forms part of the spliceosomes in the brain. A systematic search for other imprinted genes in the Prader-Willi syndrome region revealed a paternally expressed transcript (IPW, for imprinted in the Prader-Willi region) and a similarly imprinted mouse homologue (Ipw) in the conserved syntenic region on mouse chromosome 7. Ipw is highly expressed in the brain and alternatively spliced to generate different transcripts. Since there is no open reading frame that is conserved in the human and mouse IPW genes, they are postulated to function as untranslated RNAs, possibly regulating transcription in cis in the region.
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Affiliation(s)
- U Francke
- Department of Genetics, Beckman Center for Molecular and Genetic Medicine, CA 94305-5323, USA
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42
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Abstract
Imprinted genes are marked in the germline and retain molecular memory of their parental origin, resulting in allelic expression differences during development. Abnormalities in imprinted inheritance occur in several genetic diseases and cancer, and are exemplified by the diverse genetic defects involving chromosome 15q11-q13 in Prader-Willi (PWS) and Angelman (AS) syndromes. PWS involves loss of function of multiple paternally expressed genes, while mutations in a single gene, UBE3A, which is subject to spatially restricted imprinting, occur in some AS patients. Identification of mutations in the imprinting process in PWS and AS has led to a definition of an imprinting center (IC), involving the promoter (in PWS) or an alternative transcript of the SNRPN gene (in AS). The IC regulates initiation of imprint switching for all genes in a 2 Mb imprinted domain during gametogenesis. Imprinting mutations define a novel mechanism of genetic disease because they have no direct effect in the affected patient but, rather, it is the parental germline effect of an IC mutation that leads to disease in the offspring.
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Affiliation(s)
- R D Nicholls
- Department of Genetics, Case Western Reserve University, Cleveland, OH, USA
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43
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Abstract
Prader-Willi syndrome (PWS) is characterized by psychomotor and growth retardation, infantile hypotonia, characteristic facies, small hands and feet, dental abnormalities, and early onset of childhood hyperphagia with consequent obesity. PWS is associated with abnormalities of chromosome 15. Approximately 75% of patients have a deletion of 15q11q13 on the paternal homologue, whereas 20-25% have inherited both chromosome 15s from the mother and none from the father, a condition known as maternal uniparental disomy (UPD). Thus, it is a lack of paternal alleles in the 15q11q13 region that results in PWS. Thick, sticky saliva is a consistent finding in patients with PWS. We have characterized salivary flow and composition in individuals with PWS. Salivary flow in patients with PWS is approximately 20% of that in controls. In addition, the salivary ions and proteins are present in increased amounts, possibly reflecting a concentration effect relative to decreased water in the saliva. Both deletion and uniparental disomy patients exhibit these findings, suggesting that the gene(s) involved are subject to imprinting.
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Affiliation(s)
- P S Hart
- Department of Pediatrics/Section on Medical Genetics, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27157, USA.
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44
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Lyko F, Buiting K, Horsthemke B, Paro R. Identification of a silencing element in the human 15q11-q13 imprinting center by using transgenic Drosophila. Proc Natl Acad Sci U S A 1998; 95:1698-702. [PMID: 9465079 PMCID: PMC19156 DOI: 10.1073/pnas.95.4.1698] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Prader-Willi syndrome (PWS) and Angelman syndrome are neurogenetic disorders caused by the lack of a paternal or a maternal contribution from human chromosome 15q11-q13, respectively. Deletions in the transcription unit of the imprinted SNRPN gene have been found in patients who have PWS or Angelman syndrome because of a parental imprint switch failure in this chromosomal domain. It has been suggested that the SNRPN exon 1 region, which is deleted in the PWS patients, contains an imprint switch element from which the maternal and paternal epigenotypes of the 15q11-q13 domain originate. Using the model organism Drosophila, we show here that a fragment from this region can function as a silencer in transgenic flies. Repression was detected specifically from this element and could not be observed with control human sequences. Additional experiments allowed the delineation of the silencer to a fragment of 215 bp containing the SNRPN promoter region. These results provide an additional link between genomic imprinting and an evolutionary conserved silencing mechanism. We suggest that the identified element participates in the long range regulation of the imprinted 15q11-q13 domain or locally represses SNRPN expression from the maternal allele.
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Affiliation(s)
- F Lyko
- Zentrum für Molekulare Biologie Heidelberg, University of Heidelberg, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany
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45
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Christian SL, Bhatt NK, Martin SA, Sutcliffe JS, Kubota T, Huang B, Mutirangura A, Chinault AC, Beaudet AL, Ledbetter DH. Integrated YAC contig map of the Prader-Willi/Angelman region on chromosome 15q11-q13 with average STS spacing of 35 kb. Genome Res 1998; 8:146-57. [PMID: 9477342 PMCID: PMC310691 DOI: 10.1101/gr.8.2.146] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Prader-Willi syndrome and Angelman syndrome are associated with parent-of-origin-specific abnormalities of chromosome 15q11-q13, most frequently a deletion of an approximately 4-Mb region. Because of genomic imprinting, paternal deficiency of this region leads to PWS and maternal deficiency to AS. Additionally, this region is frequently involved in other chromosomal rearrangements including duplications, triplications, or supernumerary marker formation. A detailed physical map of this region is important for elucidating the genes and mechanisms involved in genomic imprinting, as well as for understanding the mechanism of recurrent chromosomal rearrangments. An initial YAC contig extended from D15S18 to D15S12 and was comprised of 23 YACs and 21 STSs providing an average resolution of about one STS per 200 kb. To close two gaps in this contig, YAC screening was performed using two STSs that flank the gap between D15S18 and 254B5R and three STSs located distal to the GABRA5-149A9L gap. Additionally, we developed 11 new STSs, including seven polymorphic markers. Although several groups have developed whole-genome genetic and radiation hybrid maps, the depth of coverage for 15q11-q13 has been somewhat limited and discrepancies in marker order exist between the maps. To resolve the inconsistencies and to provide a more detailed map order of STSs in this region, we have constructed an integrated YAC STS-based physical map of chromosome 15q11-q13 containing 118 YACs and 118 STSs, including 38 STRs and 49 genes/ESTs. Using an estimate of 4 Mb for the size of this region, the map provides an average STS spacing of 35 kb. This map provides a valuable resource for identification of disease genes localized to this region as well as a framework for complete DNA sequencing.
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Affiliation(s)
- S L Christian
- Department of Human Genetics, The University of Chicago, Chicago, Illinois 60637, USA
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46
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Abstract
The UBE3A gene encodes the E6-AP ubiquitin-protein ligase and has recently been shown to be mutated in Angelman syndrome patients who lack 15q11-q13 deletions or chromosome 15 paternal uniparental disomy. Previous UBE3A cDNA analysis has shown a coding region of approximately 2.6 kb and a 3'-untranslated region (UTR) of < 50 bp, whereas Northern analysis has indicated mRNA sizes of 5-8 kb. We have analyzed additional cDNA clones and provide evidence for an additional 0.5 kb of 5'-UTR and > 2 kb of 3'-UTR. We have established the genomic organization of UBE3A and the sequence of intron-exon borders. We have also mapped two highly homologous processed pseudogenes, UBE3AP1 and UBE3AP2, to chromosomes 2 and 21, respectively, and determined their genomic organization. These results will form the basis for studies of mutation and imprinting of UBE3A.
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Affiliation(s)
- T Kishino
- Genetics Division, Children's Hospital, Boston, Massachusetts, USA
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47
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Abstract
Parental-specific differences in the expression of certain genes (imprinting), may be implicated in the pathogenesis of anomalous gestations, but only a minority manifest themselves as malformation syndromes. Delayed or lost gestations are much more frequent sequelae, as are those disorganized to such an extent that they are usually classified as neoplastic rather than developmental processes. Expression levels from imprinted loci are dependent not only on the number of genomic alleles present and their structural integrity, but also on their specific parental origin. Anomalous expression of imprinted genes during development is sometimes caused by imbalanced representation of maternal and paternal contributions, 'uniparental disomy'. Uniparental parthenogenetic or androgenetic gestations form ovarian teratomas or complete hydatidiform moles, respectively--examples of an arrested developmental program. Uniparental disomy of individual chromosomes or portions thereof has been associated with developmental delay or gestational loss. The phenotype of hemizygous mutation or deletion of imprinted genes is modified by the parental origin of the mutant copy, with dichotomous syndromes defined by parental inheritance, as in the Prader-Willi and Angelman syndromes. Lastly, failure of the imprinting process itself, 'loss of imprinting', may quantitatively alter expression levels of normally imprinted transforming or tumor-suppressing genes, thereby increasing risk for developmental tumors such as Wilms' tumor or choriocarcinoma.
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Affiliation(s)
- G L Mutter
- Brigham and Women's Hospital, Department of Pathology, Boston, MA 02115, USA.
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48
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Abstract
The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are distinct neurogenetic disorders that are caused by a deficiency of paternal (PWS) or maternal (AS) contributions to chromosome 15. The affected genes are located in an imprinted chromosomal domain of 2 Mb, which is controlled by an imprinting center (IC). The IC has been mapped to a 100-kb region including the SNRPN gene and appears to have a bipartite structure. Mutations of the proximal part of the IC block the paternal-->maternal imprint switch during female gametogenesis, whereas mutations of the distal part of the IC block the maternal-->paternal imprint switch during, male gametogenesis. Imprinting involves differential DNA methylation, which appears to be instrumental in the regulation of gene activity and can be used for diagnostic purposes.
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Affiliation(s)
- B Horsthemke
- Institut für Humangenetik, Universität Klinikum Essen, Germany
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49
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Meguro M, Mitsuya K, Sui H, Shigenami K, Kugoh H, Nakao M, Oshimura M. Evidence for uniparental, paternal expression of the human GABAA receptor subunit genes, using microcell-mediated chromosome transfer. Hum Mol Genet 1997; 6:2127-33. [PMID: 9328477 DOI: 10.1093/hmg/6.12.2127] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have constructed mouse A9 hybrids containing a single normal human chromosome 15, via microcell-mediated chromosome transfer. Cytogenetic and DNA-polymorphic analyses identified mouse A9 hybrids that contained either a paternal or maternal human chromosome 15. Paternal specific expression of the known imprinted genes SNRPN (small nuclear ribonucleoprotein-associated polypeptide N gene) and IPW (imprinted gene in the Prader-Willi syndrome region) was maintained in the A9 hybrids. Using this system, we first demonstrated that human GABAAreceptor subunit genes, GABRB3 , GABRA5 and GABRG3 , were expressed exclusively from the paternal allele and that E6-AP (E6-associated protein or UBE3A ) was biallelically expressed. Moreover, the 5' portion of the GABRB3 gene was found to be hypermethylated on the paternal allele. Our data imply that GABAAreceptor subunit genes are imprinted and are possible candidates for Prader-Willi syndrome, and that this human monochromosomal hybrid system enables the efficient analysis of imprinted loci.
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Affiliation(s)
- M Meguro
- Department of Molecular and Cell Genetics, School of Life Sciences, Faculty of Medicine, Tottori University, Nishimachi 86, Yonago, Tottori 683, Japan
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50
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Albrecht U, Sutcliffe JS, Cattanach BM, Beechey CV, Armstrong D, Eichele G, Beaudet AL. Imprinted expression of the murine Angelman syndrome gene, Ube3a, in hippocampal and Purkinje neurons. Nat Genet 1997; 17:75-8. [PMID: 9288101 DOI: 10.1038/ng0997-75] [Citation(s) in RCA: 358] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Angelman syndrome (AS) is a human genetic disorder characterized by mental retardation, seizures, inappropriate laughter, abnormal galt, tremor and ataxia. There is strong genetic evidence that the disorder is associated with a maternally expressed, imprinted gene mapping to chromosome 15q11-13. Affected patients demonstrate varied molecular abnormalities, including large maternal deletions, uniparental paternal disomy (UPD). Imprinting mutations and loss of function mutations of E6-associated-protein (E6-AP) ubiquitin-protein ligase (UBE3A). All of these abnormalities are associated with loss of maternal expression of UBE3A. Although mutations in UBE3A cause AS, indicating that maternal-specific expression of UBE3A is essential for a normal phenotype, evidence for maternal-specific expression of UBE3A has been lacking. Using mice with partial paternal UPD encompassing Ube3a to differentiate maternal and paternal expression, we found by in situ hybridization that expression of Ube3a in Purkinje cells, hippocampal neurons and mitral cells of the olfactory bulb in UPD mice was markedly reduced compared to non-UPD littermates. In contrast, expression of Ube3a in other regions of the brain was only moderately or not at all reduced in UPD mice. The major phenotypic features of AS correlate with the loss of maternal-specific expression of Ube3a in hippocampus and cerebellum as revealed in the mouse model.
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Affiliation(s)
- U Albrecht
- Department of Biochemistry, Baylor College of Medicine, Houston, Texas, USA.
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