Parkinson's disease-linked mutations in VPS35 induce dopaminergic neurodegeneration

Mutations in the vacuolar protein sorting 35 homolog (VPS35) gene at the PARK17 locus, encoding a key component of the retromer complex, were recently identified as a new cause of late-onset, autosomal dominant Parkinson's disease (PD). Here we explore the pathogenic consequences of PD-associated mutations in VPS35 using a number of model systems. VPS35 exhibits a broad neuronal distribution throughout the rodent brain, including within the nigrostriatal dopaminergic pathway. In the human brain, VPS35 protein levels and distribution are similar in tissues from control and PD subjects, and VPS35 is not associated with Lewy body pathology. The common D620N missense mutation in VPS35 does not compromise its protein stability or localization to endosomal and lysosomal vesicles, or the vesicular sorting of the retromer cargo, sortilin, SorLA and cation-independent mannose 6-phosphate receptor, in rodent primary neurons or patient-derived human fibroblasts. In yeast we show that PD-linked VPS35 mutations are functional and can normally complement VPS35 null phenotypes suggesting that they do not result in a loss-of-function. In rat primary cortical cultures the overexpression of human VPS35 induces neuronal cell death and increases neuronal vulnerability to PD-relevant cellular stress. In a novel viral-mediated gene transfer rat model, the expression of D620N VPS35 induces the marked degeneration of substantia nigra dopaminergic neurons and axonal pathology, a cardinal pathological hallmark of PD. Collectively, these studies establish that dominant VPS35 mutations lead to neurodegeneration in PD consistent with a gain-of-function mechanism, and support a key role for VPS35 in the development of PD

Born too young and likely to die : Should this continue?

Peer reviewe

Modest phenotypic improvements in ASA-deficient mice with only one UDP-galactose:ceramide-galactosyltransferase gene

BACKGROUND: Arylsulfatase A (ASA)-deficient mice are a model for the lysosomal storage disorder metachromatic leukodystrophy. This lipidosis is characterised by the lysosomal accumulation of the sphingolipid sulfatide. Storage of this lipid is associated with progressive demyelination. We have mated ASA-deficient mice with mice heterozygous for a non-functional allele of UDP-galactose:ceramide-galactosyltransferase (CGT). This deficiency is known to lead to a decreased synthesis of galactosylceramide and sulfatide, which should reduce sulfatide storage and improve pathology in ASA-deficient mice. RESULTS: ASA-/- CGT+/- mice, however, showed no detectable decrease in sulfatide storage. Neuronal degeneration of cells in the spiral ganglion of the inner ear, however, was decreased. Behavioural tests showed small but clear improvements of the phenotype in ASA-/- CGT+/- mice. CONCLUSION: Thus the reduction of galactosylceramide and sulfatide biosynthesis by genetic means overall causes modest improvements of pathology

Stronger Neural Modulation by Visual Motion Intensity in Autism Spectrum Disorders

Theories of autism spectrum disorders (ASD) have focused on altered perceptual integration of sensory features as a possible core deficit. Yet, there is little understanding of the neuronal processing of elementary sensory features in ASD. For typically developed individuals, we previously established a direct link between frequency-specific neural activity and the intensity of a specific sensory feature: Gamma-band activity in the visual cortex increased approximately linearly with the strength of visual motion. Using magnetoencephalography (MEG), we investigated whether in individuals with ASD neural activity reflect the coherence, and thus intensity, of visual motion in a similar fashion. Thirteen adult participants with ASD and 14 control participants performed a motion direction discrimination task with increasing levels of motion coherence. A polynomial regression analysis revealed that gamma-band power increased significantly stronger with motion coherence in ASD compared to controls, suggesting excessive visual activation with increasing stimulus intensity originating from motion-responsive visual areas V3, V6 and hMT/V5. Enhanced neural responses with increasing stimulus intensity suggest an enhanced response gain in ASD. Response gain is controlled by excitatory-inhibitory interactions, which also drive high-frequency oscillations in the gamma-band. Thus, our data suggest that a disturbed excitatoryinhibitory balance underlies enhanced neural responses to coherent motion in ASD

A Rapid and Sensitive Method for Measuring NAcetylglucosaminidase Activity in Cultured Cells

A rapid and sensitive method to quantitatively assess N-acetylglucosaminidase (NAG) activity in cultured cells is highly desirable for both basic research and clinical studies. NAG activity is deficient in cells from patients with Mucopolysaccharidosis type IIIB (MPS IIIB) due to mutations in NAGLU, the gene that encodes NAG. Currently available techniques for measuring NAG activity in patient-derived cell lines include chromogenic and fluorogenic assays and provide a biochemical method for the diagnosis of MPS IIIB. However, standard protocols require large amounts of cells, cell disruption by sonication or freeze-thawing, and normalization to the cellular protein content, resulting in an error-prone procedure that is material- and time-consuming and that produces highly variable results. Here we report a new procedure for measuring NAG activity in cultured cells. This procedure is based on the use of the fluorogenic NAG substrate, 4- Methylumbelliferyl-2-acetamido-2-deoxy-alpha-D-glucopyranoside (MUG), in a one-step cell assay that does not require cell disruption or post-assay normalization and that employs a low number of cells in 96-well plate format. We show that the NAG one-step cell assay greatly discriminates between wild-type and MPS IIIB patient-derived fibroblasts, thus providing a rapid method for the detection of deficiencies in NAG activity. We also show that the assay is sensitive to changes in NAG activity due to increases in NAGLU expression achieved by either overexpressing the transcription factor EB (TFEB), a master regulator of lysosomal function, or by inducing TFEB activation chemically. Because of its small format, rapidity, sensitivity and reproducibility, the NAG one-step cell assay is suitable for multiple procedures, including the high-throughput screening of chemical libraries to identify modulators of NAG expression, folding and activity, and the investigation of candidate molecules and constructs for applications in enzyme replacement therapy, gene therapy, and combination therapies

Activity of faecal fluid of a leaf-cutting ant toward plant cell wall polysaccharides

The faecal fluid of the leaf-cutting ant, Atta colombica tonsipes, has been shown to contain enzymes active in the degradation of pectin, sodium polypectate, xylan, and carboxymethylcellulose. In addition, glycosidase activity has been detected in the faecal fluid using various naturally occurring disaccharides and synthetic p-nitrophenyl glycosides as substrates. The importance of these enzymes in the symbiosis between A. c. tonsipes and its food fungus is discussed, with particular emphasis on the role of the pectin-degrading enzymes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21944/1/0000351.pd

Digitization and automation of training and development in organizations: chances, challenges, and application examples

Dieser Beitrag in der Zeitschrift „Gruppe. Interaktion. Organisation. (GIO)“ gibt einen Überblick über die vielfältigen Digitalisierungs- und Automatisierungsmöglichkeiten, die aktuelle technologische Entwicklungen für die Weiterbildung in Organisationen eröffnen, und diskutiert Chancen und Risken ihres Einsatzes. Um wettbewerbsfähig, effizient und produktiv zu bleiben, müssen Organisationen sicherstellen, dass ihre Beschäftigten sich fortwährend weiterbilden und entwickeln. Die Weiterbildung aller Beschäftigten in allen notwendigen Kompetenzbereichen durch entsprechende Maßnahmen beansprucht jedoch viele Ressourcen. Um diese Ressourcen optimal einsetzen zu können, muss der Kompetenzentwicklungsbedarf der Beschäftigten kontinuierlich und zutreffend ermittelt werden, damit dieser auch durch passende Weiterbildungsmaßnahmen gezielt und adäquat adressiert werden kann. Auch diese übergeordneten Prozesse der Weiterbildung sind ressourcenintensiv. Daher wurde bereits in der Vergangenheit eine Vielzahl von Technologien eingesetzt, um die organisationale Weiterbildung (bspw. durch digital zur Verfügung gestellte Materialien zum Selbststudium) und die damit zusammenhängenden Prozesse durch Digitalisierung effizienter gestalten und verwalten zu können. In diesem Beitrag betrachten wir vor allem die vielfältigen Digitalisierungs- und Automatisierungsmöglichkeiten, die aktuelle technologische Entwicklungen eröffnen, und führen diese – strukturiert am Prozess der Personalentwicklung – mit Beispielen aus Forschung und Praxis aus.This article in the journal “Gruppe. Interaktion. Organisation. (GIO)” provides an overview of the manifold digitization and automation possibilities that current technological developments provide for training and development and discusses the opportunities and risks of their use. To remain competitive, efficient, and productive, organizations need to ensure that their employees continue to learn and develop. However, training all employees in all necessary competencies requires a lot of resources. To be able to use these resources optimally, the developmental needs of the employees must be determined continuously and accurately so that these can be addressed in a targeted and adequate manner through suitable training and development activities. These administrative processes of training and development are also resource-intensive. For this reason, organizations made use of a variety of technologies in the past to make training and development and the associated administrative processes more efficient and manageable through digitization (e.g., by providing digital learning materials). In this article, we highlight the diverse digitization and automation possibilities that current technological developments offer and illustrate them—structured along the process of personnel development—with examples from research and practice

Individual Actin Filaments in a Microfluidic Flow Reveal the Mechanism of ATP Hydrolysis and Give Insight Into the Properties of Profilin

A novel microfluidic approach allows the analysis of the dynamics of individual actin filaments, revealing both their local ADP/ADP-Pi-actin composition and that Pi release is a random mechanism