Modelling Ser129 Phosphorylation Inhibits Membrane Binding of Pore-Forming Alpha-Synuclein Oligomers

Background: In several neurodegenerative diseases, hyperphosphorylation at position Ser129 is found in fibrillar deposits of alpha-synuclein (asyn), implying a pathophysiological role of asyn phosphorylation in neurodegeneration. However, recent animal models applying asyn phosphorylation mimics demonstrated a protective effect of phosphorylation. Since metal-ion induced asyn oligomers were identified as a potential neurotoxic aggregate species with membrane pore-forming abilities, the current study was undertaken to determine effects of asyn phosphorylation on oligomer membrane binding. Methods: We investigated the influence of S129 phosphorylation on interactions of metal-ion induced asyn oligomers with small unilamellar lipid vesicles (SUV) composed of POPC and DPPC applying the phosphorylation mimic asyn129E. Confocal single-particle fluorescence techniques were used to monitor membrane binding at the single-particle level. Results: Binding of asyn129E monomers to gel-state membranes (DPPC-SUV) is slightly reduced compared to wild-type asyn, while no interactions with membranes in the liquid-crystalline state (POPC-SUV) are seen for both asyn and asyn129E. Conversely, metal-ion induced oligomer formation is markedly increased in asyn129E. Surprisingly, membrane binding to POPC-SUV is nearly absent in Fe3+ induced asyn129E oligomers and markedly reduced in Al3+ induced oligomers. Conclusion: The protective effect of pseudophosphorylation seen in animal models may be due to impeded oligomer membrane binding. Phosphorylation at Ser129 may thus have a protective effect against neurotoxic asyn oligomers by preventing oligomer membrane binding and disruption of the cellular electrophysiological equilibrium. Importantly, these findings put a new complexion on experimental pharmaceutical interventions against POLO-2 kinase

Hierarchical imaging: a new concept for targeted imaging of large volumes from cells to tissues

Background: Imaging large volumes such as entire cells or small model organisms at nanoscale resolution seemed an unrealistic, rather tedious task so far. Now, technical advances have lead to several electron microscopy (EM) large volume imaging techniques. One is array tomography, where ribbons of ultrathin serial sections are deposited on solid substrates like silicon wafers or glass coverslips. Results: To ensure reliable retrieval of multiple ribbons from the boat of a diamond knife we introduce a substrate holder with 7 axes of translation or rotation specifically designed for that purpose. With this device we are able to deposit hundreds of sections in an ordered way in an area of 22 × 22 mm, the size of a coverslip. Imaging such arrays in a standard wide field fluorescence microscope produces reconstructions with 200 nm lateral resolution and 100 nm (the section thickness) resolution in z. By hierarchical imaging cascades in the scanning electron microscope (SEM), using a new software platform, we can address volumes from single cells to complete organs. In our first example, a cell population isolated from zebrafish spleen, we characterize different cell types according to their organelle inventory by segmenting 3D reconstructions of complete cells imaged with nanoscale resolution. In addition, by screening large numbers of cells at decreased resolution we can define the percentage at which different cell types are present in our preparation. With the second example, the root tip of cress, we illustrate how combining information from intermediate resolution data with high resolution data from selected regions of interest can drastically reduce the amount of data that has to be recorded. By imaging only the interesting parts of a sample considerably less data need to be stored, handled and eventually analysed. Conclusions: Our custom-designed substrate holder allows reproducible generation of section libraries, which can then be imaged in a hierarchical way. We demonstrate, that EM volume data at different levels of resolution can yield comprehensive information, including statistics, morphology and organization of cells and tissue. We predict, that hierarchical imaging will be a first step in tackling the big data issue inevitably connected with volume EM

Novel non-heteroarylpyrimidine (HAP) capsid assembly modifiers have a different mode of action from HAPs in vitro

One of the most promising viral targets in current hepatitis B virus (HBV) drug development is the core protein due to its multiple roles in the viral life cycle. Here we investigated the differences in the mode of action and antiviral activity of representatives of six different capsid assembly modifier (CAM) scaffolds: three from the well-characterized scaffolds heteroarylpyrimidine (HAP), sulfamoylbenzamide (SBA), and phenylpropenamide (PPA), and three from novel scaffolds glyoxamide-pyrrolamide (GPA), pyrazolyl-thiazole (PT), and dibenzo-thiazepin-2-one (DBT). The target activity and antiviral efficacy of the different CAMs were tested in biochemical and cellular assays. Analytical size exclusion chromatography and transmission electron microscopy showed that only the HAP compound induced formation of aberrant non-capsid structures (class II mode of action), while the remaining CAMs did not affect capsid gross morphology (class I mode of action). Intracellular lysates from the HepAD38 cell line, inducibly replicating HBV, showed no reduction in the quantities of intracellular core protein or capsid after treatment with SBA, PPA, GPA, PT, or DBT compounds; however HAP-treatment led to a profound decrease in both. Additionally, immunofluorescence staining of compound-treated HepAD38 cells showed that all non-HAP CAMs led to a shift in the equilibrium of HBV core antigen (HBcAg) towards complete cytoplasmic staining, while the HAP induced accumulation of HBcAg aggregates in the nucleus. Our study demonstrates that the novel scaffolds GPA, PT, and DBT exhibit class I modes of action, alike SBA and PPA, whereas HAP remains the only scaffold belonging to class II inhibitors

AI-based multi-PRS models outperform classical single-PRS models

Polygenic risk scores (PRS) calculate the risk for a specific disease based on the weighted sum of associated alleles from different genetic loci in the germline estimated by regression models. Recent advances in genetics made it possible to create polygenic predictors of complex human traits, including risks for many important complex diseases, such as cancer, diabetes, or cardiovascular diseases, typically influenced by many genetic variants, each of which has a negligible effect on overall risk. In the current study, we analyzed whether adding additional PRS from other diseases to the prediction models and replacing the regressions with machine learning models can improve overall predictive performance. Results showed that multi-PRS models outperform single-PRS models significantly on different diseases. Moreover, replacing regression models with machine learning models, i.e., deep learning, can also improve overall accuracy

Genome-wide mapping of genetic determinants influencing DNA methylation and gene expression in human hippocampus

Emerging evidence emphasizes the strong impact of regulatory genomic elements in neurodevelopmental processes and the complex pathways of brain disorders. The present genome-wide quantitative trait loci analyses explore the cis-regulatory effects of single-nucleotide polymorphisms (SNPs) on DNA methylation (meQTL) and gene expression (eQTL) in 110 human hippocampal biopsies. We identify cis-meQTLs at 14,118 CpG methylation sites and cis-eQTLs for 302 3'-mRNA transcripts of 288 genes. Hippocampal cis-meQTL-CpGs are enriched in flanking regions of active promoters, CpG island shores, binding sites of the transcription factor CTCF and brain eQTLs. Cis-acting SNPs of hippocampal meQTLs and eQTLs significantly overlap schizophrenia-associated SNPs. Correlations of CpG methylation and RNA expression are found for 34 genes. Our comprehensive maps of cis-acting hippocampal meQTLs and eQTLs provide a link between disease-associated SNPs and the regulatory genome that will improve the functional interpretation of non-coding genetic variants in the molecular genetic dissection of brain disorders

Liquidity and market efficiency in the world’s largest carbon market

We investigate liquidity and market efficiency on the world's largest carbon exchange, IntercontinentalExchange Inc.’s European Climate Exchange (ECX), by using intraday short-horizon return predictability as an inverse indicator of market efficiency. We find a strong relationship between liquidity and market efficiency such that when spreads narrow, return predictability diminishes. This is more pronounced for the highest trading carbon futures and during periods of low liquidity. Since the start of trading in Phase II of the EU Emissions Trading Scheme (EU-ETS) prices have continuously moved nearer to unity with efficient, random walk benchmarks, and this improves from year to year. Overall, our findings suggest that trading quality in the EU-ETS has improved markedly and matures over the 2008–2011 compliance years

Production of monoclonal antibodies with a controlled N-glycosylation pattern in seeds of Arabidopsis thaliana

Seed-specific expression is an appealing alternative technology for the production of recombinant proteins in transgenic plants. Whereas attractive yields of recombinant proteins have been achieved by this method, little attention has been paid to the intracellular deposition and the quality of such products. Here, we demonstrate a comparative study of two antiviral monoclonal antibodies (mAbs) (HA78 against Hepatitis A virus; 2G12 against HIV) expressed in seeds of Arabidopsis wild-type (wt) plants and glycosylation mutants lacking plant specific N-glycan residues. We demonstrate that 2G12 is produced with complex N-glycans at great uniformity in the wt as well as in the glycosylation mutant, carrying a single dominant glycosylation species, GnGnXF and GnGn, respectively. HA78 in contrast, contains additionally to complex N-glycans significant amounts of oligo-mannosidic structures, which are typical for endoplasmic reticulum (ER)-retained proteins. A detailed subcellular localization study demonstrated the deposition of both antibodies virtually exclusively in the extracellular space, illustrating their efficient secretion. In addition, although a KDEL-tagged version of 2G12 exhibited an ER-typical N-glycosylation pattern, it was surprisingly detected in protein storage vacuoles. The different antibody variants showed different levels of degradation with hardly any degradation products detectable for HA78 carrying GnGnXF glycans. Finally, we demonstrate functional integrity of the HA78 and 2G12 glycoforms using viral inhibition assays. Our data therefore demonstrate the usability of transgenic seeds for the generation of mAbs with a controlled N-glycosylation pattern, thus expanding the possibilities for the production of optimally glycosylated proteins with enhanced biological activities for the use as human therapeutics

Additional file 3: Figure S3. of Hierarchical imaging: a new concept for targeted imaging of large volumes from cells to tissues

3D CAD model of substrate holder, front view (TIFF 3032 kb