Erioflorin stabilizes the tumor suppressor Pdcd4 by inhibiting its interaction with the E3-ligase β-TrCP1

Loss of the tumor suppressor Pdcd4 was reported for various tumor entities and proposed as a prognostic marker in tumorigenesis. We previously characterized decreased Pdcd4 protein stability in response to mitogenic stimuli, which resulted from p70S6K1-dependent protein phosphorylation, β-TrCP1-mediated ubiquitination, and proteasomal destruction. Following high-throughput screening of natural product extract libraries using a luciferase-based reporter assay to monitor phosphorylation-dependent proteasomal degradation of the tumor suppressor Pdcd4, we succeeded in showing that a crude extract from Eriophyllum lanatum stabilized Pdcd4 from TPA-induced degradation. Erioflorin was identified as the active component and inhibited not only degradation of the Pdcd4-luciferase-based reporter but also of endogenous Pdcd4 at low micromolar concentrations. Mechanistically, erioflorin interfered with the interaction between the E3-ubiquitin ligase β-TrCP1 and Pdcd4 in cell culture and in in vitro binding assays, consequently decreasing ubiquitination and degradation of Pdcd4. Interestingly, while erioflorin stabilized additional β-TrCP-targets (such as IκBα and β-catenin), it did not prevent the degradation of targets of other E3-ubiquitin ligases such as p21 (a Skp2-target) and HIF-1α (a pVHL-target), implying selectivity for β-TrCP. Moreover, erioflorin inhibited the tumor-associated activity of known Pdcd4- and IκBα-regulated αtranscription factors, that is, AP-1 and NF-κB, altered cell cycle progression and suppressed proliferation of various cancer cell lines. Our studies succeeded in identifying erioflorin as a novel Pdcd4 stabilizer that inhibits the interaction of Pdcd4 with the E3-ubiquitin ligase β-TrCP1. Inhibition of E3-ligase/target-protein interactions may offer the possibility to target degradation of specific proteins only as compared to general proteasome inhibition

Catalytic pyrolysis of crude glycerol over shaped ZSM-5/bentonite catalysts for bio-BTX synthesis

Ex-situ catalytic pyrolysis of crude glycerol for the synthesis of bio-based benzene, toluene and xylenes (bio-BTX) was performed in a tandem micro-reactor (TMR), a batch gram scale reactor and a continuous integrated bench scale unit using ZSM-5/bentonite extrudates. A bio-BTX yield of 8.1 wt.% (14.6% carbon yield) based on crude glycerol was obtained over the fresh catalysts (Cat-F) in the bench scale unit (crude glycerol feed rate of 200 g h−1, pyrolysis temperature of 520 °C and catalytic upgrading temperature of 536 °C). Catalyst activity was shown to be a function of the time on stream (TOS) and after 4.7 h the activity dropped with about 8%. After an oxidative regeneration step to remove coke, the activity of the regenerated catalysts (Cat-R1) was recovered to 95% of the original catalyst activity. After 11 reaction-regeneration cycles, the bio-BTX yield decreased to 5.4 wt.% (9.7% carbon yield) over Cat-R11. The fresh, deactivated and regenerated ZSM-5/bentonite catalysts were characterized in detail using nitrogen physisorption, XRD, ICP-AES, EA, TEM-EDX, TGA, NH3-TPD, pyridine-IR and solid MAS NMR. Coke (10.5 wt.% over Cat-D) was mostly deposited on ZSM-5 planes, and not only decreased the number of Lewis and Brönsted acid sites, but also blocked the pores, resulting in catalyst deactivation. Coke removal was effectively performed using an oxidative treatment. However, exchange of cations (e.g., Na) of the bentonite and possibly also from the crude glycerol feed with protons of ZSM-5 was observed, leading to irreversible deactivation. Furthermore, the layered structure of bentonite collapsed due to the removal of interlamellar water and dehydroxylation

Nutritional consulting in regular veterinary practices in Belgium and the Netherlands

BACKGROUND: Increased interest in nutrition by dog and cat owners stresses the importance of providing tailored nutritional guidance for each patient by veterinarians. The World Small Animal Veterinary Association (WSAVA) has provided guidelines to help veterinarians implement this in every-day patient care, by screening patients for the presence of nutritional risk factors, establishing tailored nutritional plans and providing adequate patient follow-up tools. OBJECTIVES: This study aimed to assess the use of nutritional assessments in companion animal practices, and to investigate differences between Dutch and Belgian veterinarians. METHODS: A survey was conducted among Dutch and Belgian veterinarians. Of the 423 respondents, 53% were from Belgium, and 47% were from the Netherlands. RESULTS: Only 21% had prior knowledge of the WSAVA nutritional assessment guidelines. General trends in the usage of nutritional assessments were similar in the examined countries. Aside from weighing, diet evaluation by collecting dietary information and body condition or muscle condition scoring were used infrequently, mostly due to insufficient knowledge of the methods. Nutritional recommendations were often made as part of a treatment plan, and were mostly made by veterinarians, but in Dutch practices also by veterinary nurses. CONCLUSION: Despite the fact that nutritional recommendations are a regular part of treatment plans, nutritional risk factors may be missed due to a lack of completely performed nutritional assessments. It remains important to promote the benefits of regular nutritional assessments to veterinarians, which will improve patients' health

Multi-step self-guided pathways for shape-changing metamaterials

Multi-step pathways, constituted of a sequence of reconfigurations, are central to a wide variety of natural and man-made systems. Such pathways autonomously execute in self-guided processes such as protein folding and self-assembly, but require external control in macroscopic mechanical systems, provided by, e.g., actuators in robotics or manual folding in origami. Here we introduce shape-changing mechanical metamaterials, that exhibit self-guided multi-step pathways in response to global uniform compression. Their design combines strongly nonlinear mechanical elements with a multimodal architecture that allows for a sequence of topological reconfigurations, i.e., modifications of the topology caused by the formation of internal self-contacts. We realized such metamaterials by digital manufacturing, and show that the pathway and final configuration can be controlled by rational design of the nonlinear mechanical elements. We furthermore demonstrate that self-contacts suppress pathway errors. Finally, we demonstrate how hierarchical architectures allow to extend the number of distinct reconfiguration steps. Our work establishes general principles for designing mechanical pathways, opening new avenues for self-folding media, pluripotent materials, and pliable devices in, e.g., stretchable electronics and soft robotics.Comment: 16 pages, 3 main figures, 10 extended data figures. See https://youtu.be/8m1QfkMFL0I for an explanatory vide

Peptide exchange on MHC-I by TAPBPR is driven by a negative allostery release cycle.

Chaperones TAPBPR and tapasin associate with class I major histocompatibility complexes (MHC-I) to promote optimization (editing) of peptide cargo. Here, we use solution NMR to investigate the mechanism of peptide exchange. We identify TAPBPR-induced conformational changes on conserved MHC-I molecular surfaces, consistent with our independently determined X-ray structure of the complex. Dynamics present in the empty MHC-I are stabilized by TAPBPR and become progressively dampened with increasing peptide occupancy. Incoming peptides are recognized according to the global stability of the final pMHC-I product and anneal in a native-like conformation to be edited by TAPBPR. Our results demonstrate an inverse relationship between MHC-I peptide occupancy and TAPBPR binding affinity, wherein the lifetime and structural features of transiently bound peptides control the regulation of a conformational switch located near the TAPBPR binding site, which triggers TAPBPR release. These results suggest a similar mechanism for the function of tapasin in the peptide-loading complex

From mesoscale to nanoscale mechanics in single-wall carbon nanotubes

The experimental work was carried out in collaboration with W. Wenseleers and S. Cambré at the University of Antwerp, Belgium. The computational results presented have been achieved in part using the Vienna Scientific Cluster (VSC). DJD is grateful for support from the Region Rhône-Alpes through the programme “Accueil-PRO 2014” and from the iMUST Labex programme “Mobility in 2015”. ACTD, TFTC, WC, MALM, SB, DM and ASM acknowledge support from the French Agence Nationale de la Recherche through contract ANR-11-NANO-025 “TRI-CO”. ACTD acknowledges postdoctoral grant from Brazilian Ministry of Education (CAPES)

Vertical distribution of methane oxidation and methanotrophic response to elevated methane concentrations in stratified waters of the Arctic fjord Storfjorden (Svalbard, Norway)

The bacterially mediated aerobic methane oxidation (MOx) is a key mechanism in controlling methane (CH₄) emissions from the world’s oceans to the atmosphere. In this study, we investigated MOx in the Arctic fjord Storfjorden (Svalbard) by applying a combination of radio-tracerbased incubation assays (³H-CH₄ and ¹⁴C-CH₄), stable CCH₄ isotope measurements, and molecular tools (16S rRNA gene Denaturing Gradient Gel Electrophoresis (DGGE) fingerprinting, pmoA- and mxaF gene analyses). Storfjorden is stratified in the summertime with melt water (MW) in the upper 60m of the water column, Arctic water (ArW) between 60 and 100 m, and brine-enriched shelf water (BSW) down to 140 m. CH₄ concentrations were supersaturated with respect to the atmospheric equilibrium (about 3–4 nM) throughout the water column, increasing from ~20nM at the surface to a maximum of 72nM at 60m and decreasing below. MOx rate measurements at near in situ CH₄ concentrations (here measured with ³H-CH₄ raising the ambient CH₄ pool by >2 nM) showed a similar trend: low rates at the sea surface, increasing to a maximum of ~2.3nMday⁻¹ at 60 m, followed by a decrease in the deeper ArW/BSW. In contrast, rate measurements with ¹⁴C-CH₄ (incubations were spiked with ~450nM of ¹⁴C-CH₄, providing an estimate of the CH₄ oxidation at elevated concentration) showed comparably low turnover rates (>1nMday⁻¹) at 60 m, and peak rates were found in ArW/BSW at ~100m water depth, concomitant with increasing ¹³C values in the residual CH₄ pool. Our results indicate that the MOx community in the surface MW is adapted to relatively low CH₄ concentrations. In contrast, the activity of the deep-water MOx community is relatively low at the ambient, summertime CH₄ concentrations but has the potential to increase rapidly in response to CH⁴ availability. A similar distinction between surface and deepwater MOx is also suggested by our molecular analyses. The DGGE banding patterns of 16S rRNA gene fragments of the surface MW and deep water were clearly different. A DGGE band related to the known type I MOx bacterium Methylosphaera was observed in deep BWS, but absent in surface MW. Furthermore, the Polymerase Chain Reaction (PCR) amplicons of the deep water with the two functional primers sets pmoA and mxaF showed, in contrast to those of the surface MW, additional products besides the expected one of 530 base pairs (bp). Apparently, different MOx communities have developed in the stratified water masses in Storfjorden, which is possibly related to the spatiotemporal variability in CH₄ supply to the distinct water masses