scholarly journals BIOLOGICAL SCIENCES: Genetics

2018 ◽  
Author(s):  
Jack S. Hsiao ◽  
Noelle D. Germain ◽  
Andrea Wilderman ◽  
Christopher Stoddard ◽  
Luke A. Wojenski ◽  
...  
Keyword(s):  
Boundary Element ◽  
Angelman Syndrome ◽  
Antisense Transcript ◽  
Neurodevelopmental Disorder ◽  
Boundary Function ◽  
Paternal Allele ◽  
Loss Of Function ◽  
Maternal Allele ◽  
Specific Expression ◽  
Human Neurons

ABSTRACTAngelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of function from the maternal allele of UBE3A, a gene encoding an E3 ubiquitin ligase. UBE3A is only expressed from the maternally-inherited allele in mature human neurons due to tissue-specific genomic imprinting. Imprinted expression of UBE3A is restricted to neurons by expression of UBE3A antisense transcript (UBE3A-ATS) from the paternally-inherited allele, which silences the paternal allele of UBE3A in cis. However, the mechanism restricting UBE3A-ATS expression and UBE3A imprinting to neurons is not understood. We used CRISPR/Cas9-mediated genome editing to functionally define a bipartite boundary element critical for neuron-specific expression of UBE3A-ATS in humans. Removal of this element led to upregulation of UBE3A-ATS without repressing paternal UBE3A. However, increasing expression of UBE3A-ATS in the absence of the boundary element resulted in full repression of paternal UBE3A, demonstrating that UBE3A imprinting requires both the loss of function from the boundary element as well as upregulation of UBE3A-ATS. These results suggest that manipulation of the competition between UBE3A-ATS and UBE3A may provide a potential therapeutic approach for AS.SIGNIFICANCE STATEMENTAngelman syndrome is a neurodevelopmental disorder caused by loss of function from the maternal allele of UBE3A, an imprinted gene. The paternal allele of UBE3A is silenced by a long, non-coding antisense transcript in mature neurons. We have identified a boundary element that stops the transcription of the antisense transcript in human pluripotent stem cells, and thus restricts UBE3A imprinted expression to neurons. We further determined that UBE3A imprinting requires both the loss of the boundary function and sufficient expression of the antisense transcript to silence paternal UBE3A. These findings provide essential details about the mechanisms of UBE3A imprinting that may suggest additional therapeutic approaches for Angelman syndrome.

scholarly journals A bipartite boundary element restrictsUBE3Aimprinting to mature neurons

2019 ◽  
Vol 116 (6) ◽  
pp. 2181-2186 ◽  
Author(s):  
Jack S. Hsiao ◽  
Noelle D. Germain ◽  
Andrea Wilderman ◽  
Christopher Stoddard ◽  
Luke A. Wojenski ◽  
...  
Keyword(s):  
Boundary Element ◽  
Antisense Transcript ◽  
Neurodevelopmental Disorder ◽  
Paternal Allele ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Specific Expression ◽  
Human Neurons ◽  
Mature Neurons ◽  
Ube3a Antisense

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of function from the maternal allele ofUBE3A, a gene encoding an E3 ubiquitin ligase.UBE3Ais only expressed from the maternally inherited allele in mature human neurons due to tissue-specific genomic imprinting. Imprinted expression ofUBE3Ais restricted to neurons by expression ofUBE3A antisense transcript(UBE3A-ATS) from the paternally inherited allele, which silences the paternal allele ofUBE3Aincis. However, the mechanism restrictingUBE3A-ATSexpression andUBE3Aimprinting to neurons is not understood. We used CRISPR/Cas9-mediated genome editing to functionally define a bipartite boundary element critical for neuron-specific expression ofUBE3A-ATSin humans. Removal of this element led to up-regulation ofUBE3A-ATSwithout repressing paternalUBE3A. However, increasing expression ofUBE3A-ATSin the absence of the boundary element resulted in full repression of paternalUBE3A, demonstrating thatUBE3Aimprinting requires both the loss of function from the boundary element as well as the up-regulation ofUBE3A-ATS. These results suggest that manipulation of the competition betweenUBE3A-ATSandUBE3Amay provide a potential therapeutic approach for AS.

scholarly journals Identification of disease-linked hyperactivating mutations in UBE3A through large-scale functional variant analysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kellan P. Weston ◽  
Xiaoyi Gao ◽  
Jinghan Zhao ◽  
Kwang-Soo Kim ◽  
Susan E. Maloney ◽  
...  
Keyword(s):  
Angelman Syndrome ◽  
Large Scale ◽  
Phenotypic Diversity ◽  
Function Analysis ◽  
Genetic Disorders ◽  
Neurodevelopmental Disorder ◽  
Loss Of Function ◽  
Monogenic Disorders ◽  
Functional Variant ◽  
Variant Analysis

AbstractThe mechanisms that underlie the extensive phenotypic diversity in genetic disorders are poorly understood. Here, we develop a large-scale assay to characterize the functional valence (gain or loss-of-function) of missense variants identified in UBE3A, the gene whose loss-of-function causes the neurodevelopmental disorder Angelman syndrome. We identify numerous gain-of-function variants including a hyperactivating Q588E mutation that strikingly increases UBE3A activity above wild-type UBE3A levels. Mice carrying the Q588E mutation exhibit aberrant early-life motor and communication deficits, and individuals possessing hyperactivating UBE3A variants exhibit affected phenotypes that are distinguishable from Angelman syndrome. Additional structure-function analysis reveals that Q588 forms a regulatory site in UBE3A that is conserved among HECT domain ubiquitin ligases and perturbed in various neurodevelopmental disorders. Together, our study indicates that excessive UBE3A activity increases the risk for neurodevelopmental pathology and suggests that functional variant analysis can help delineate mechanistic subtypes in monogenic disorders.

scholarly journals Deleting a UBE3A substrate rescues impaired hippocampal physiology and learning in Angelman syndrome mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gabrielle L. Sell ◽  
Wendy Xin ◽  
Emily K. Cook ◽  
Mark A. Zbinden ◽  
Thomas B. Schaffer ◽  
...  
Keyword(s):  
Angelman Syndrome ◽  
Developmental Disorders ◽  
Motor Coordination ◽  
Synapse Formation ◽  
Neurodevelopmental Disorder ◽  
Autism Spectrum ◽  
Loss Of Function ◽  
Behavioral Deficits ◽  
Altered Expression ◽  
Exciting Potential

AbstractIn humans, loss-of-function mutations in the UBE3A gene lead to the neurodevelopmental disorder Angelman syndrome (AS). AS patients have severe impairments in speech, learning and memory, and motor coordination, for which there is currently no treatment. In addition, UBE3A is duplicated in > 1–2% of patients with autism spectrum disorders—a further indication of the significant role it plays in brain development. Altered expression of UBE3A, an E3 ubiquitin ligase, is hypothesized to lead to impaired levels of its target proteins, but identifying the contribution of individual UBE3A targets to UBE3A-dependent deficits remains of critical importance. Ephexin5 is a putative UBE3A substrate that has restricted expression early in development, regulates synapse formation during hippocampal development, and is abnormally elevated in AS mice, modeled by maternally-derived Ube3a gene deletion. Here, we report that Ephexin5 can be directly ubiquitylated by UBE3A. Furthermore, removing Ephexin5 from AS mice specifically rescued hippocampus-dependent behaviors, CA1 physiology, and deficits in dendritic spine number. Our findings identify Ephexin5 as a key driver of hippocampal dysfunction and related behavioral deficits in AS mouse models. These results demonstrate the exciting potential of targeting Ephexin5, and possibly other UBE3A substrates, to improve symptoms of AS and other UBE3A-related developmental disorders.

scholarly journals Seizure-like activity in a juvenile Angelman syndrome mouse model is attenuated by reducing Arc expression

2015 ◽  
Vol 112 (16) ◽  
pp. 5129-5134 ◽  
Author(s):  
Caleigh Mandel-Brehm ◽  
John Salogiannis ◽  
Sameer C. Dhamne ◽  
Alexander Rotenberg ◽  
Michael E. Greenberg
Keyword(s):  
Angelman Syndrome ◽  
Motor Coordination ◽  
Neural Circuit ◽  
Brain Activity ◽  
Neurodevelopmental Disorder ◽  
Ultrasonic Vocalizations ◽  
Therapeutic Interventions ◽  
Motor Deficits ◽  
Loss Of Function ◽  
Circuit Defects

Angelman syndrome (AS) is a neurodevelopmental disorder arising from loss-of-function mutations in the maternally inherited copy of the UBE3A gene, and is characterized by an absence of speech, excessive laughter, cognitive delay, motor deficits, and seizures. Despite the fact that the symptoms of AS occur in early childhood, behavioral characterization of AS mouse models has focused primarily on adult phenotypes. In this report we describe juvenile behaviors in AS mice that are strain-independent and clinically relevant. We find that young AS mice, compared with their wild-type littermates, produce an increased number of ultrasonic vocalizations. In addition, young AS mice have defects in motor coordination, as well as abnormal brain activity that results in an enhanced seizure-like response to an audiogenic challenge. The enhanced seizure-like activity, but not the increased ultrasonic vocalizations or motor deficits, is rescued in juvenile AS mice by genetically reducing the expression level of the activity-regulated cytoskeleton-associated protein, Arc. These findings suggest that therapeutic interventions that reduce the level of Arc expression have the potential to reverse the seizures associated with AS. In addition, the identification of aberrant behaviors in young AS mice may provide clues regarding the neural circuit defects that occur in AS and ultimately allow new approaches for treating this disorder.

scholarly journals Angelman syndrome imprinting center encodes a transcriptional promoter

2014 ◽  
Vol 112 (22) ◽  
pp. 6871-6875 ◽  
Author(s):  
Michael W. Lewis ◽  
Jason O. Brant ◽  
Joseph M. Kramer ◽  
James I. Moss ◽  
Thomas P. Yang ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Angelman Syndrome ◽  
Paternal Allele ◽  
Specific Gene ◽  
Prader Willi Syndrome ◽  
Maternal Allele ◽  
Expression Of Genes ◽  
Imprinting Center ◽  
Maternal Contribution ◽  
Parent Of Origin

Clusters of imprinted genes are often controlled by an imprinting center that is necessary for allele-specific gene expression and to reprogram parent-of-origin information between generations. An imprinted domain at 15q11–q13 is responsible for both Angelman syndrome (AS) and Prader–Willi syndrome (PWS), two clinically distinct neurodevelopmental disorders. Angelman syndrome arises from the lack of maternal contribution from the locus, whereas Prader–Willi syndrome results from the absence of paternally expressed genes. In some rare cases of PWS and AS, small deletions may lead to incorrect parent-of-origin allele identity. DNA sequences common to these deletions define a bipartite imprinting center for the AS–PWS locus. The PWS–smallest region of deletion overlap (SRO) element of the imprinting center activates expression of genes from the paternal allele. The AS–SRO element generates maternal allele identity by epigenetically inactivating the PWS–SRO in oocytes so that paternal genes are silenced on the future maternal allele. Here we have investigated functional activities of the AS–SRO, the element necessary for maternal allele identity. We find that, in humans, the AS–SRO is an oocyte-specific promoter that generates transcripts that transit the PWS–SRO. Similar upstream promoters were detected in bovine oocytes. This result is consistent with a model in which imprinting centers become DNA methylated and acquire maternal allele identity in oocytes in response to transiting transcription.

Molecular Analysis of an Extra inv dup(15)(q13) Chromosome in Two Patients with Angelman Syndrome

1996 ◽  
Vol 45 (1-2) ◽  
pp. 217-220 ◽  
Author(s):  
T. Buchholz ◽  
S. Schuffenhauer ◽  
K. Evans ◽  
L. Robson ◽  
B. Appleton ◽  
...  
Keyword(s):  
Molecular Analysis ◽  
Angelman Syndrome ◽  
Uniparental Disomy ◽  
Molecular Data ◽  
Monoallelic Expression ◽  
Chromosome 15 ◽  
Prader Willi Syndrome ◽  
Loss Of Function ◽  
Maternal Allele ◽  
Molecular Defects

Angelman syndrome (AS) is caused by the loss of function of yet unidentified gene(s) which map within 15q 11-13 and show monoallelic expression from the maternal allele. Lack of the maternal allele(s), due to either a deletion on the maternal chromosome 15 (about 70% of AS patients) or a paternal uniparental disomy (UPD)15 (<5%), are the most common molecular defects in AS. Prader-Willi syndrome (PWS) also maps to proximal 15q, but is caused by the loss of function of paternally expressed gen(s) [1]. Here we describe clinical, cytogenetic and molecular data for two non-related patients with AS who carry a nonmosaic extra cromosome inv dup(15).

scholarly journals Antisense oligonucleotides targeting UBE3A-ATS restore expression of UBE3A by relieving transcriptional interference

2021 ◽  
Author(s):  
Noelle D. Germain ◽  
Dea Gorka ◽  
Ryan Drennan ◽  
Amanda Whipple ◽  
Paymaan Jafar-nejad ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Antisense Oligonucleotides ◽  
Noncoding Rna ◽  
Neurodevelopmental Disorder ◽  
Paternal Allele ◽  
Transcriptional Interference ◽  
Loss Of Function ◽  
Definitive Evidence ◽  
Promising Therapeutic Approach ◽  
In Cis

Angelman syndrome (AS) is a rare neurodevelopmental disorder caused by loss of function of the maternally inherited UBE3A allele. In neurons, the paternal allele of UBE3A is silenced in cis by the long noncoding RNA, UBE3A-ATS. Unsilencing paternal UBE3A by reducing UBE3A-ATS is a promising therapeutic approach for the treatment of AS. Here we show that targeted cleavage of UBE3A-ATS using antisense oligonucleotides (ASOs) restores UBE3A and rescues electrophysiological phenotypes in human AS neurons. We demonstrate that cleavage of UBE3A-ATS results in termination of its transcription by displacement of RNA Polymerase II. Reduced transcription of UBE3A-ATS allows transcription of UBE3A to proceed to completion, providing definitive evidence for the transcriptional interference model of paternal UBE3A silencing. These insights into the mechanism by which ASOs restore UBE3A inform the future development of nucleotide-based approaches for the treatment of AS, including alternative strategies for cleaving UBE3A-ATS that can be developed for long-term restoration of UBE3A function.

scholarly journals Prader-Willi syndrome: reflections on seminal studies and future therapies

Open Biology ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 200195
Author(s):  
Michael S. Chung ◽  
Maéva Langouët ◽  
Stormy J. Chamberlain ◽  
Gordon G. Carmichael
Keyword(s):  
Genomic Imprinting ◽  
Angelman Syndrome ◽  
Cpg Island ◽  
Uniparental Disomy ◽  
Large Deletion ◽  
Paternal Allele ◽  
Prader Willi Syndrome ◽  
Loss Of Function ◽  
Maternal Uniparental Disomy ◽  
Parental Allele

Prader-Willi syndrome (PWS) is caused by the loss of function of the paternally inherited 15q11-q13 locus. This region is governed by genomic imprinting, a phenomenon in which genes are expressed exclusively from one parental allele. The genomic imprinting of the 15q11-q13 locus is established in the germline and is largely controlled by a bipartite imprinting centre. One part, termed the Prader-Willi syndrome imprinting center (PWS-IC), comprises a CpG island that is unmethylated on the paternal allele and methylated on the maternal allele. The second part, termed the Angelman syndrome imprinting centre, is required to silence the PWS_IC in the maternal germline. The loss of the paternal contribution of the imprinted 15q11-q13 locus most frequently occurs owing to a large deletion of the entire imprinted region but can also occur through maternal uniparental disomy or an imprinting defect. While PWS is considered a contiguous gene syndrome based on large-deletion and uniparental disomy patients, the lack of expression of only non-coding RNA transcripts from the SNURF-SNRPN/SNHG14 may be the primary cause of PWS. Patients with small atypical deletions of the paternal SNORD116 cluster alone appear to have most of the PWS related clinical phenotypes. The loss of the maternal contribution of the 15q11-q13 locus causes a separate and distinct condition called Angelman syndrome. Importantly, while much has been learned about the regulation and expression of genes and transcripts deriving from the 15q11-q13 locus, there remains much to be learned about how these genes and transcripts contribute at the molecular level to the clinical traits and developmental aspects of PWS that have been observed.

scholarly journals Emerging Gene and Small Molecule Therapies for the Neurodevelopmental Disorder Angelman Syndrome

2021 ◽  
Author(s):  
Nycole A. Copping ◽  
Stephanie M. McTighe ◽  
Kyle D. Fink ◽  
Jill L. Silverman
Keyword(s):  
Small Molecule ◽  
Angelman Syndrome ◽  
Sleep Disturbances ◽  
Single Gene ◽  
Neurodevelopmental Disorder ◽  
The Body ◽  
Motor Deficits ◽  
Loss Of Function ◽  
Gene Therapies ◽  
High Prevalence

AbstractAngelman syndrome (AS) is a rare (~1:15,000) neurodevelopmental disorder characterized by severe developmental delay and intellectual disability, impaired communication skills, and a high prevalence of seizures, sleep disturbances, ataxia, motor deficits, and microcephaly. AS is caused by loss-of-function of the maternally inherited UBE3A gene. UBE3A is located on chromosome 15q11–13 and is biallelically expressed throughout the body but only maternally expressed in the brain due to an RNA antisense transcript that silences the paternal copy. There is currently no cure for AS, but advancements in small molecule drugs and gene therapies offer a promising approach for the treatment of the disorder. Here, we review AS and how loss-of-function of the maternal UBE3A contributes to the disorder. We also discuss the strengths and limitations of current animal models of AS. Furthermore, we examine potential small molecule drug and gene therapies for the treatment of AS and associated challenges faced by the therapeutic design. Finally, gene therapy offers the opportunity for precision medicine in AS and advancements in the treatment of this disorder can serve as a foundation for other single-gene neurodevelopmental disorders.

scholarly journals H3K9 methyltransferase EHMT2/G9a controls ERVK-driven noncanonical imprinted genes

Epigenomics ◽  
2021 ◽  
Author(s):  
Tie-Bo Zeng ◽  
Nicholas Pierce ◽  
Ji Liao ◽  
Piroska E Szabó
Keyword(s):  
Dna Methylation ◽  
X Chromosome ◽  
X Chromosome Inactivation ◽  
Paternal Allele ◽  
Imprinted Genes ◽  
Rna Seq ◽  
Maternal Allele ◽  
Specific Expression ◽  
Allele Specific ◽  
Ectoplacental Cone

Aim: Paternal allele-specific expression of noncanonical imprinted genes in the extraembryonic lineages depends on an H3K27me3-based imprint in the oocyte, which is not a lasting mark. We hypothesized that EHMT2, the main euchromatic H3K9 dimethyltransferase, also has a role in controlling noncanonical imprinting. Methods: We carried out allele-specific total RNA-seq analysis in the ectoplacental cone of somite-matched 8.5 days post coitum embryos using reciprocal mouse crosses. Results: We found that the maternal allele of noncanonical imprinted genes was derepressed from its ERVK promoter in the Ehmt2-/- ectoplacental cone. In Ehmt2-/- embryos, loss of DNA methylation accompanied biallelic derepression of the ERVK promoters. Canonical imprinting and imprinted X chromosome inactivation were generally undisturbed. Conclusion: EHMT2 is essential for repressing the maternal allele in noncanonical imprinting.

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