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UBE3A expression analysis is consistent with the overexpression of UBE3A transcript in patient's fibroblasts compared with three (control 1, 2, and 3) age- and sex-matched controls. Two amplicons (UBE3A_1 and UBE3A_2) were used to perform the test.
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Duplications of chromosome region 15q11-q13 with the maternal imprint are associated with a wide spectrum of neuropsychiatric disorders including, autism spectrum disorders (ASD), developmental delay, learning difficulties, schizophrenia and seizures. These observations suggest there is a dosage sensitive imprinted gene or genes within this region...
Citations
... E6AP has been found to not only be important for normal neurological development, but to also require a precise dosage in the cell for normal func,on. Duplica,ons and dele,on in the maternally inherited allele as well as loss-of-func,on muta,ons of E6AP have been shown to produce Angelman Syndrome and Angelman Syndrome-like symptoms while gene duplica,on is also associated with Au,sm Spectrum Disorder in pa,ents [13][14][15] . ...
The E3-ubiquitin ligase E6AP degrades p53 when complexed with the viral protein E6 from human papilloma virus (HPV), which contributes to the transformation of cells in HPV-related cancers. Previous crystal structures of the E6AP-E6-p53 ternary complex have implicated a peptide containing an LxxLL motif from E6AP as the interface between the three proteins. However, the contributions to the ternary complex from the remainder of the E6AP protein remain unknown. We reexamined this complex using cryo-EM and full-length proteins and find additional protein interaction interfaces involving a previously uncharacterized domain of E6AP. Additionally, we observe that the ternary complex forms both 1:1:1 and 2:2:2 stochiometric complexes comprised of E6AP, E6 and p53.
... 4 Deletion or mutation of the maternal allele resulting in UBE3A loss of function causes Angelman syndrome (AS), a severe neurodevelopmental disorder with symptoms that include intellectual disability, microcephaly, seizures, a happy demeanor, speech impairment, and motor dysfunction. 3,[5][6][7] Duplication or triplication of maternal UBE3A is linked to neurodevelopmental disorders with clinical features that are distinct from AS. 6,[8][9][10] Overall, these disorders highlight how precise regulation of UBE3A expression and function is necessary for normal brain development. ...
The E3 ubiquitin ligase Ube3a is biallelically expressed in neural progenitors and glial cells, suggesting that UBE3A gain-of-function mutations might cause neurodevelopmental disorders irrespective of parent of origin. Here, we engineered a mouse line that harbors an autism-linked UBE3AT485A (T503A in mouse) gain-of-function mutation and evaluated phenotypes in animals that inherited the mutant allele paternally, maternally, or from both parents. We find that paternally and maternally expressed UBE3AT503A results in elevated UBE3A activity in neural progenitors and glial cells. Expression of UBE3AT503A from the maternal allele, but not the paternal one, leads to a persistent elevation of UBE3A activity in neurons. Mutant mice display behavioral phenotypes that differ by parent of origin. Expression of UBE3AT503A, irrespective of its parent of origin, promotes transient embryonic expansion of Zcchc12 lineage interneurons. Phenotypes of Ube3aT503A mice are distinct from Angelman syndrome model mice. Our study has clinical implications for a growing number of disease-linked UBE3A gain-of-function mutations.
... Duplication in 15q11-13: The finding of about 5-Mb long duplications in schizophrenics supports the claim that SZ belongs to the spectrum 15q11-13 duplication syndrome disease (Ingason et al. 2011b;Liao et al. 2012). An atypical 0.129-Mb long duplication involving only the UBE3A gene was also found (Noor et al. 2015). ...
Schizophrenia (SZ) is a highly inherited disease that affects ~0.5% of the population. The genetic and environmental factors are involved in its aetiology and they interact with each other. Combination of symptoms is unique to each patient, the disease seriously interferes with the ability to function in society and affects the mental state of the patient. In most patients, the first manifestations of SZ appear during the adolescence or early adulthood. The hypothesis that SZ origin in impaired development of the nervous system is currently widely accepted. Some studies have identified several genetic and environmental factors that increase the risk of the disease manifestation, but none of them can be considered as the only cause of SZ. The genetics of the disease is complex and in last two decades it is assumed that the cryptic rearrangements could be one of its causes. Cryptic rearrangements (microdeletions and microduplications) are the chromosomal rearrangements smaller than 3–5 Mb. Their discovery was conditioned by the development of molecular genetic and molecular cytogenetic techniques. The aberrations affect one or more genes and change the gene dose. In this article, we present the rearrangements of the regions of human chromosomes more closely associated with the onset and development of SZ. Next, the candidate genes will be presented together with their inclusion in the context of theories trying to explain the origin of SZ through some important factors (e.g. action of dopamine or glutamate or GABA, formation of dendrites and neuronal synapses, etc.).
... 29,30 On the other hand, the duplication of the Ube3a gene in the maternal chromosome is associated with autism spectrum disorders. 31,32 Ube3a is normally expressed from both paternal and maternal copies of the chromosome in the peripheral tissues. The binding of the E6 protein of the human papillomavirus (HPV) with UBE3A would induce the degradation of the tumor suppressor p53, which is causative for the development of cervical cancer. ...
Nonalcoholic fatty liver disease (NAFLD) is substantiated by the reprogramming of liver metabolic pathways that disrupts the homeostasis of lipid and glucose metabolism and thus promotes the progression of the disease. The metabolic pathways associated with NAFLD are regulated at different levels from gene transcription to various post-translational modifications including ubiquitination. Here, we used a novel orthogonal ubiquitin transfer platform to identify pyruvate dehydrogenase A1 (PDHA1) and acetyl-CoA acetyltransferase 1 (ACAT1), two important enzymes that regulate glycolysis and ketogenesis, as substrates of E3 ubiquitin ligase UBE3A/E6AP. We found that overexpression of UBE3A accelerated the degradation of PDHA1 and promoted glycolytic activities in HEK293 cells. Furthermore, a high-fat diet suppressed the expression of UBE3A in the mouse liver, which was associated with increased ACAT1 protein levels, while forced expression of UBE3A in the mouse liver resulted in decreased ACAT1 protein contents. As a result, the mice with forced expression of UBE3A in the liver exhibited enhanced accumulation of triglycerides, cholesterol, and ketone bodies. These results reveal the role of UBE3A in NAFLD development by inducing the degradation of ACAT1 in the liver and promoting lipid storage. Overall, our work uncovers an important mechanism underlying the regulation of glycolysis and lipid metabolism through UBE3A-mediated ubiquitination of PDHA1 and ACAT1 to regulate their stabilities and enzymatic activities in the cell.
... Thus, neuronal UBE3A overdosage is unique to maternally inherited 15q11.2-q13.1 duplications, which yield far more severe neurodevelopmental phenotypes as compared with those of paternal origin (11,15,26). Additionally, maternal inheritance of a circumscribed UBE3A gene duplication has been linked to developmental delay and neuropsychiatric phenotypes in multiple members of a single family; family members with paternal inheritance of the same mutation were unaffected (27). Such findings have focused the lens on UBE3A gene duplications as being a major driver of disease pathology in Dup15q syndrome. ...
... Although UBE3A deficiency indisputably leads to Angelman syndrome (14), a causal connection between UBE3A overexpression and Dup15q syndrome phenotypes has proved elusive. Not only is clinical evidence of UBE3A microduplication sparse (27), but also studies of the consequences of UBE3A overexpression in mouse models are contradictory. In 2009, Nakatani and colleagues reported on mice harboring a duplication of chromosome 7, the syntenic 15q11.2-q13.1 region in mice. ...
... That we observed a lack of cellular and behavioral phenotypes despite such marked increases in Ube3a gene copy number speaks to a relatively robust neurodevelopmental tolerance of UBE3A overdosage in mice, at least in the absence of concomitant overexpression of nonimprinted 15q11.2-q13.1 gene homologs. Succinctly, given both the available clinical data detailing relatively mild neuropsychiatric outcomes in cases of UBE3A microduplication (27), and our findings in the Ube3a OE models, UBE3A overexpression appears to be necessary, but not sufficient, to drive the pathophysiological mechanisms that underlie Dup15q syndrome. ...
Chromosome 15q11.2-q13.1 duplication syndrome (Dup15q syndrome) is a severe neurodevelopmental disorder characterized by intellectual disability, impaired motor coordination, and autism spectrum disorder. Chromosomal multiplication of the UBE3A gene is presumed to be the primary driver of Dup15q pathophysiology, given that UBE3A exhibits maternal monoallelic expression in neurons and that maternal duplications typically yield far more severe neurodevelopmental outcomes than paternal duplications. However, studies into the pathogenic effects of UBE3A overexpression in mice have yielded conflicting results. Here, we investigated the neurodevelopmental impact of Ube3a gene overdosage using bacterial artificial chromosome-based transgenic mouse models (Ube3aOE) that recapitulate the increases in Ube3a copy number most often observed in Dup15q. In contrast to previously published Ube3a overexpression models, Ube3aOE mice were indistinguishable from wild-type controls on a number of molecular and behavioral measures, despite suffering increased mortality when challenged with seizures, a phenotype reminiscent of sudden unexpected death in epilepsy. Collectively, our data support a model wherein pathogenic synergy between UBE3A and other overexpressed 15q11.2-q13.1 genes is required for full penetrance of Dup15q syndrome phenotypes.
... Overexpression of UBE3A can disrupt these systems, which disturbs the excitatory-inhibitory balance in the brain, possibly leading to psychosis [57]. The hypothesis that overexpression of UBE3A can result in psychosis is supported by studies about patients with a 15q11-q13 duplication [58,59]. Isles et al. found that maternal duplications of this region are associated with psychosis [58]. ...
... Isles et al. found that maternal duplications of this region are associated with psychosis [58]. Additionally, Noor et al. reported symptoms of psychosis in patients with maternal microduplications of UBE3A only [59]. Notably, both studies also reported symptoms of autism, which suggests that overexpression of UBE3A might also contribute to the increased prevalence of autistic characteristics in patients with an mUPD [60,61]. ...
Prader–Willi syndrome (PWS) is a complex, rare genetic disorder caused by a loss of expression of paternally expressed genes on chromosome 15q11.2-q13. The most common underlying genotypes are paternal deletion (DEL) and maternal uniparental disomy (mUPD). DELs can be subdivided into type 1 (DEL-1) and (smaller) type 2 deletions (DEL-2). Most research has focused on behavioral, cognitive and psychological differences between the different genotypes. However, little is known about physical health problems in relation to genetic subtypes. In this cross-sectional study, we compare physical health problems and other clinical features among adults with PWS caused by DEL (N = 65, 12 DEL-1, 27 DEL-2) and mUPD (N = 65). A meta-analysis, including our own data, showed that BMI was 2.79 kg/m2 higher in adults with a DEL (p = 0.001). There were no significant differences between DEL-1 and DEL-2. Scoliosis was more prevalent among adults with a DEL (80% vs. 58%; p = 0.04). Psychotic episodes were more prevalent among adults with an mUPD (44% vs. 9%; p < 0.001). In conclusion, there were no significant differences in physical health outcomes between the genetic subtypes, apart from scoliosis and BMI. The differences in health problems, therefore, mainly apply to the psychological domain.
... In the 16p11.2 locus, a prominent study using zebrafish identified KCTD13 as the key causal gene in the locus 36 In the 15q11-13 locus encompassing 11 genes, several studies have identified UBE3A as the major causal gene for ASD 48,49 . Although there is supporting evidence for other candidate causal genes such as CYFIP1 and HERC2 in the locus 50,51 , there is also evidence supporting that CYFIP1 is not a causal gene in the locus 52 . ...
Cerebral organoids can be used to gain insights into cell type specific processes perturbed by genetic variants associated with neuropsychiatric disorders. However, robust and scalable phenotyping of organoids remains challenging. Here, we perform RNA sequencing on 71 samples comprising 1,420 cerebral organoids from 25 donors, and describe a framework (Orgo-Seq) to integrate bulk RNA and single-cell RNA sequence data. We apply Orgo-Seq to 16p11.2 deletions and 15q11–13 duplications, two loci associated with autism spectrum disorder, to identify immature neurons and intermediate progenitor cells as critical cell types for 16p11.2 deletions. We further applied Orgo-Seq to identify cell type-specific driver genes. Our work presents a quantitative phenotyping framework to integrate multi-transcriptomic datasets for the identification of cell types and cell type-specific co-expressed driver genes associated with neuropsychiatric disorders.
... However, there are only two known examples that specifically link UBE3A gain-offunction to neurodevelopmental disease. This includes one de novo hyperactivating missense mutation identified in a child with autism 12,13 , and a microduplication of UBE3A that segregates with neuropsychiatric phenotypes in one family 14 . These limited observations have raised questions about the extent to which excessive UBE3A activity contributes to neurodevelopmental pathology. ...
... However, we stress that careful consideration must be given when attributing this phenotype to gain-of-function mutations in UBE3A. A previous study noted that individuals who possess a microduplication encompassing only maternal UBE3A exhibited developmental delay, intellectual disability, and behavioral abnormalities, but none of these individuals presented with seizures 14 . In the current study, we observed that seizures were not always a shared phenotype among siblings with the same UBE3A gain-of-function mutation (Fig. 7b). ...
The 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. UBE3A gene dysregulation is associated with neurodevelopmental disorders, but predicting the function of UBE3A variants remains difficult. The authors use a high-throughput assay to categorize variants by functional activity, and show that UBE3A hyperactivity increases the risk of neurodevelopmental disease.
... The neurodevelopmental impact of UBE3A overexpression apart from that of the other ~20 overexpressed genes in this chromosomal region is unknown, but familial cases of circumscribed maternal UBE3A duplication have shed some light on the matter. Compared with individuals with Dup15q syndrome, individuals with selective UBE3A duplication had favorable neurodevelopmental outcomes characterized by a spectrum of variably diagnosed, relatively mild neuropsychiatric phenotypes, including developmental delay, autistic features, depression, and anxiety (65). ...
Loss of the maternal UBE3A allele causes Angelman syndrome (AS), a debilitating neurodevelopmental disorder. Here, we devised an AS treatment strategy based on reinstating dual-isoform expression of human UBE3A (hUBE3A) in the developing brain. Kozak sequence engineering of our codon-optimized vector (hUBE3Aopt) enabled translation of both short and long hUBE3A protein isoforms at a near-endogenous 3:1 (short/long) ratio, a feature that could help to support optimal therapeutic outcomes. To model widespread brain delivery and early postnatal onset of hUBE3A expression, we packaged the hUBE3Aopt vector into PHP.B capsids and performed intracerebroventricular injections in neonates. This treatment significantly improved motor learning and innate behaviors in AS mice, and it rendered them resilient to epileptogenesis and associated hippocampal neuropathologies induced by seizure kindling. hUBE3A overexpression occurred frequently in the hippocampus but was uncommon in the neocortex and other major brain structures; furthermore, it did not correlate with behavioral performance. Our results demonstrate the feasibility, tolerability, and therapeutic potential for dual-isoform hUBE3A gene transfer in the treatment of AS.
... In the 15q11-13 locus encompassing 11 genes, several studies have identified UBE3A as 369 the major causal gene for ASD 41,42 . Although there is supporting evidence for other candidate 370 causal genes such as CYFIP1 and HERC2 in the locus 43,44 , there is also evidence supporting that 371 CYFIP1 is not a causal gene in the locus 45 . ...
Human-derived cerebral organoids demonstrate great promise for identifying cell types and cell type specific molecular processes perturbed by genetic variants associated with neuropsychiatric and neurodevelopmental disorders, which are notoriously challenging to study using animal models. However, considerable challenges remain in achieving robust, scalable and generalizable phenotyping of organoids to discover cell types and cell type specific genes. We perform RNA sequencing on 71 samples comprising 1,420 cerebral organoids from 25 donors, and describe a framework (Orgo-Seq) to integrate bulk RNA and single-cell RNA sequence data from human post-mortem brains and cerebral organoids, for the identification of cell types and cell type specific individual genes. We apply Orgo-Seq for two autism-associated loci: 16p11.2 deletions and 15q11-13 duplications, and identify neuroepithelial cells as critical cell types for 16p11.2 deletions, and discover novel and previously reported cell type specific driver genes. Finally, we validated our results that mutations in the KCTD13 gene in the 16p11.2 locus lead to imbalances in the proportion of neuroepithelial cells, using CRISPR/Cas9-edited mosaic organoids. Our work presents a quantitative technological framework to integrate multiple transcriptomics datasets to identify cell types and cell type specific driver genes associated with complex diseases using cerebral organoids.
