The Hippocampal Response to Acute Corticosterone Elevation Is Altered in a Mouse Model for Angelman Syndrome.

Angelman Syndrome (AS) is a severe neurodevelopmental disorder, caused by the neuronal absence of the ubiquitin protein ligase E3A (UBE3A). UBE3A promotes ubiquitin-mediated protein degradation and functions as a transcriptional coregulator of nuclear hormone receptors, including the glucocorticoid receptor (GR). Previous studies showed anxiety-like behavior and hippocampal-dependent memory disturbances in AS mouse models.

From first report to clinical trials: a bibliometric overview and visualization of the development of Angelman syndrome research.

Angelman syndrome is a rare neurodevelopmental disorder caused by mutations affecting the chromosomal 15q11-13 region, either by contiguous gene deletions, imprinting defects, uniparental disomy, or mutations in the UBE3A gene itself. Phenotypic abnormalities are driven primarily, but not exclusively (especially in 15q11-13 deletion cases) by loss of expression of the maternally inherited UBE3A gene expression. The disorder was first described in 1965 by the English pediatrician Harry Angelman.

A cross-species spatiotemporal proteomic analysis identifies UBE3A-dependent signaling pathways and targets.

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of neuronal E3 ligase UBE3A. Restoring UBE3A levels is a potential disease-modifying therapy for AS and has recently entered clinical trials. There is paucity of data regarding the molecular changes downstream of UBE3A hampering elucidation of disease therapeutics and biomarkers.

Secreted retrovirus-like GAG-domain-containing protein PEG10 is regulated by UBE3A and is involved in Angelman syndrome pathophysiology.

Angelman syndrome (AS) is a neurodevelopmental disorder caused by the loss of maternal , a ubiquitin protein ligase E3A. Here, we study neurons derived from patients with AS and neurotypical individuals, and reciprocally modulate UBE3A using antisense oligonucleotides. Unbiased proteomics reveal proteins that are regulated by UBE3A in a disease-specific manner, including PEG10, a retrotransposon-derived GAG protein.

Loss of nuclear UBE3A activity is the predominant cause of Angelman syndrome in individuals carrying UBE3A missense mutations.

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by deletion (~75%) or mutation (~10%) of the ubiquitin E3 ligase A (UBE3A) gene, which encodes a HECT type E3 ubiquitin protein ligase. Although the critical substrates of UBE3A are unknown, previous studies have suggested a critical role of nuclear UBE3A in AS pathophysiology. Here, we investigated to what extent UBE3A missense mutations disrupt UBE3A subcellular localization as well as catalytic activity, stability and protein folding.

TAOK1 is associated with neurodevelopmental disorder and essential for neuronal maturation and cortical development.

Thousand and one amino-acid kinase 1 (TAOK1) is a MAP3K protein kinase, regulating different mitogen-activated protein kinase pathways, thereby modulating a multitude of processes in the cell. Given the recent finding of TAOK1 involvement in neurodevelopmental disorders (NDDs), we investigated the role of TAOK1 in neuronal function and collected a cohort of 23 individuals with mostly de novo variants in TAOK1 to further define the associated NDD. Here, we provide evidence for an important role for TAOK1 in neuronal function, showing that altered TAOK1 expression levels in the embryonic mouse brain affect neural migration in vivo, as well as neuronal maturation in vitro.

Mono-ubiquitination of Rabphilin 3A by UBE3A serves a non-degradative function.

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by brain-specific loss of UBE3A, an E3 ubiquitin protein ligase. A substantial number of possible ubiquitination targets of UBE3A have been identified, although evidence of being direct UBE3A substrates is often lacking. Here we identified the synaptic protein Rabphilin-3a (RPH3A), an effector of the RAB3A small GTPase involved in axonal vesicle priming and docking, as a ubiquitination target of UBE3A.

A novel UBE3A sequence variant identified in eight related individuals with neurodevelopmental delay, results in a phenotype which does not match the clinical criteria of Angelman syndrome.

Background: Loss of functional UBE3A, an E3 protein ubiquitin ligase, causes Angelman syndrome (AS), a neurodevelopmental disorder characterized by severe developmental delay, speech impairment, epilepsy, movement or balance disorder, and a characteristic behavioral pattern. We identified a novel UBE3A sequence variant in a large family with eight affected individuals, who did not meet the clinical AS criteria.

Methods: Detailed clinical examination and genetic analysis was performed to establish the phenotypic diversity and the genetic cause.

Conserved UBE3A subcellular distribution between human and mice is facilitated by non-homologous isoforms.

The human UBE3A gene, which is essential for normal neurodevelopment, encodes three Ubiquitin E3 ligase A (UBE3A) protein isoforms. However, the subcellular localization and relative abundance of these human UBE3A isoforms are unknown. We found, as previously reported in mice, that UBE3A is predominantly nuclear in human neurons.

Loss of nuclear UBE3A causes electrophysiological and behavioral deficits in mice and is associated with Angelman syndrome.

Mutations affecting the gene encoding the ubiquitin ligase UBE3A cause Angelman syndrome. Although most studies focus on the synaptic function of UBE3A, we show that UBE3A is highly enriched in the nucleus of mouse and human neurons. We found that the two major isoforms of UBE3A exhibit highly distinct nuclear versus cytoplasmic subcellular localization.

Regulating the human HECT E3 ligases.

Ubiquitination, the covalent attachment of ubiquitin to proteins, by E3 ligases of the HECT (homologous to E6AP C terminus) family is critical in controlling diverse physiological pathways. Stringent control of HECT E3 ligase activity and substrate specificity is essential for cellular health, whereas deregulation of HECT E3s plays a prominent role in disease. The cell employs a wide variety of regulatory mechanisms to control HECT E3 activity and substrate specificity.

A versatile plasmid system for reconstitution and analysis of mammalian ubiquitination cascades in yeast.

Ubiquitination is a posttranslational protein modification that regulates most aspects of cellular life. The sheer number of ubiquitination enzymes that are present in a mammalian cell, over 700 in total, has thus far hampered the analysis of distinct protein ubiquitination cascades in a cellular context. To overcome this complexity we have developed a versatile vector system that allows the reconstitution of specific ubiquitination cascades in the model eukaryote (baker's yeast).

Candidate CSPG4 mutations and induced pluripotent stem cell modeling implicate oligodendrocyte progenitor cell dysfunction in familial schizophrenia.

Schizophrenia is highly heritable, yet its underlying pathophysiology remains largely unknown. Among the most well-replicated findings in neurobiological studies of schizophrenia are deficits in myelination and white matter integrity; however, direct etiological genetic and cellular evidence has thus far been lacking. Here, we implement a family-based approach for genetic discovery in schizophrenia combined with functional analysis using induced pluripotent stem cells (iPSCs).

De Novo Mutations in Protein Kinase Genes CAMK2A and CAMK2B Cause Intellectual Disability.

Calcium/calmodulin-dependent protein kinase II (CAMK2) is one of the first proteins shown to be essential for normal learning and synaptic plasticity in mice, but its requirement for human brain development has not yet been established. Through a multi-center collaborative study based on a whole-exome sequencing approach, we identified 19 exceedingly rare de novo CAMK2A or CAMK2B variants in 24 unrelated individuals with intellectual disability. Variants were assessed for their effect on CAMK2 function and on neuronal migration.

LRSAM1-mediated ubiquitylation is disrupted in axonal Charcot-Marie-Tooth disease 2P.

Charcot-Marie-Tooth (CMT) disease type 2 is a genetically heterogeneous group of inherited neuropathies characterized by motor and sensory deficits as a result of peripheral axonal degeneration. We recently reported a frameshift (FS) mutation in the Really Interesting New Gene finger (RING) domain of LRSAM1 (c.2121_2122dup, p.

Binding of a proline-independent hydrophobic motif by the Candida albicans Rvs167-3 SH3 domain.

Src-homology 3 (SH3) domains are small protein-protein interaction modules. While most SH3 domains bind to proline-x-x-proline (PxxP) containing motifs in their binding partners, some SH3 domains recognize motifs other than proline-based sequences. Recently, we showed that the SH3 domain of Candida albicans Rvs167-3 binds peptides enriched in hydrophobic residues and containing a single proline residue (RΦxΦxΦP, where x is any amino acid and Φ is a hydrophobic residue).

The Deubiquitylase USP2 Regulates the LDLR Pathway by Counteracting the E3-Ubiquitin Ligase IDOL.

Rationale: The low-density lipoprotein (LDL) receptor (LDLR) is a central determinant of circulating LDL-cholesterol and as such subject to tight regulation. Recent studies and genetic evidence implicate the inducible degrader of the LDLR (IDOL) as a regulator of LDLR abundance and of circulating levels of LDL-cholesterol in humans. Acting as an E3-ubiquitin ligase, IDOL promotes ubiquitylation and subsequent lysosomal degradation of the LDLR.

Evolution of the SH3 Domain Specificity Landscape in Yeasts.

To explore the conservation of Src homology 3 (SH3) domain-mediated networks in evolution, we compared the specificity landscape of these domains among four yeast species, Saccharomyces cerevisiae, Ashbya gossypii, Candida albicans, and Schizosaccharomyces pombe, encompassing 400 million years of evolution. We first aligned and catalogued the families of SH3-containing proteins in these four species to determine the relationships between homologous domains. Then, we tagged and purified all soluble SH3 domains (82 in total) to perform a quantitative peptide assay (SPOT) for each SH3 domain.

Contribution of Fdh3 and Glr1 to Glutathione Redox State, Stress Adaptation and Virulence in Candida albicans.

The major fungal pathogen of humans, Candida albicans, is exposed to reactive nitrogen and oxygen species following phagocytosis by host immune cells. In response to these toxins, this fungus activates potent anti-stress responses that include scavenging of reactive nitrosative and oxidative species via the glutathione system. Here we examine the differential roles of two glutathione recycling enzymes in redox homeostasis, stress adaptation and virulence in C.

Ube3a reinstatement identifies distinct developmental windows in a murine Angelman syndrome model.

Angelman syndrome (AS) is a severe neurodevelopmental disorder that results from loss of function of the maternal ubiquitin protein ligase E3A (UBE3A) allele. Due to neuron-specific imprinting, the paternal UBE3A copy is silenced. Previous studies in murine models have demonstrated that strategies to activate the paternal Ube3a allele are feasible; however, a recent study showed that pharmacological Ube3a gene reactivation in adulthood failed to rescue the majority of neurocognitive phenotypes in a murine AS model.

Identification and characterization of Rvs162/Rvs167-3, a novel N-BAR heterodimer in the human fungal pathogen Candida albicans.

Membrane reshaping resides at the core of many important cellular processes, and among its mediators are the BAR (Bin, Amphiphysin, Rvs) domain-containing proteins. We have explored the diversity and function of the Rvs BAR proteins in Candida albicans and identified a novel family member, Rvs167-3 (orf19.1861).

A disulphide bond in the E2 enzyme Pex4p modulates ubiquitin-conjugating activity.

The ubiquitin-conjugating enzyme Pex4p together with its binding partner, the peroxisomal membrane protein Pex22p, co-ordinates cysteine-dependent ubiquitination of the cycling receptor protein Pex5p. Unusually for an ubiquitin-conjugating enzyme, Saccharomyces cerevisiae Pex4p can form a disulphide bond between the cysteine residues at positions 105 and 146. We found that mutating the disulphide forming cysteine residues in Pex4p to serines does not disturb the secondary structure of the protein but does reduce the in vitro activity of Pex4p.

Alternative splicing directs dual localization of Candida albicans 6-phosphogluconate dehydrogenase to cytosol and peroxisomes.

The pentose phosphate pathway (PPP) is the main source of NADPH in the cell and therefore essential for the maintenance of the redox balance and anabolic reactions. NADPH is produced by the two dehydrogenases in the oxidative branch of the PPP: glucose-6-phosphate dehydrogenase (Zwf1) and 6-phosphogluconate dehydrogenase (Gnd1). We observed that in the commensal fungus Candida albicans these two enzymes contain putative peroxisomal targeting signals (PTSs): Zwf1 has a putative PTS1, while the annotated intron of GND1 encodes a PTS2.

Insights into ubiquitin-conjugating enzyme/ co-activator interactions from the structure of the Pex4p:Pex22p complex.

Ubiquitin-conjugating enzymes (E2s) coordinate distinct types of ubiquitination via specific E3 ligases, to a large number of protein substrates. While many E2 enzymes need only the presence of an E3 ligase for substrate ubiquitination, a number of E2s require additional, non-canonical binding partners to specify their function. Here, we have determined the crystal structure and function of an E2/co-activator assembly, the Pex4p:Pex22p complex.