Search

Glucagon-like peptide-1 (GLP-1) lowers blood glucose by inducing insulin but also has other poorly understood properties. Here, we show that hydroxy amino acids (Thr11, Ser14, Ser17, Ser18) in GLP-1(7-36) act in concert to direct cell signaling. Mutating any single residue to alanine removes one hydroxyl group, thereby reducing receptor affinity and cAMP 10-fold, with Ala11 or Ala14 also reducing β-arrestin-2 10-fold, while Ala17 or Ala18 also increases ERK1/2 phosphorylation 5-fold. Multiple alanine mutations more profoundly bias signaling, differentially silencing or restoring one or more signaling properties. Mutating three serines silences only ERK1/2, the first example of such bias. Mutating all four residues silences β-arrestin-2, ERK1/2, and Ca

The actin cytoskeleton is a potentially vulnerable property of cancer cells, yet chemotherapeutic targeting attempts have been hampered by unacceptable toxicity. In this study, we have shown that it is possible to disrupt specific actin filament populations by targeting isoforms of tropomyosin, a core component of actin filaments, that are selectively upregulated in cancers. A novel class of anti-tropomyosin compounds has been developed that preferentially disrupts the actin cytoskeleton of tumor cells, impairing both tumor cell motility and viability. Our lead compound, TR100, is effective in vitro and in vivo in reducing tumor cell growth in neuroblastoma and melanoma models. Importantly, TR100 shows no adverse impact on cardiac structure and function, which is the major side effect of current anti-actin drugs. This proof-of-principle study shows that it is possible to target specific actin filament populations fundamental to tumor cell viability based on their tropomyosin isoform composition. This improvement in specificity provides a pathway to the development of a novel class of anti-actin compounds for the potential treatment of a wide variety of cancers. Cancer Res; 73(16); 5169–82. ©2013 AACR.

PDF file - 1137K, Supplementary Figure 1: Tropomyosin siRNA knockdown is isoform specific and does not result in any compensation. Supplementary Figure 2: TR100 nullifies the impact of Tm5NM1 on actin filament depolymerization kinetics. Supplementary Figure 3: Anti-Tropomyosin compound impact on the actin cytoskeleton assessed by the microfilament disruption assay. Supplementary Figure 4: TR100 targets the actin cytoskeleton and preferentially disrupts LMW-cytoskeletal tropomyosin containing filaments. Supplementary Figure 5: TR100 shows no overt impact on synaptic integrity of hippocampal neurons. Supplementary Figure 6: TR100 induces apoptosis in tumor cells via a mitochondrial pathway. Supplementary Figure 7: TR100 does not impact liver function in vivo.Supplementary Table 1: Summary of impact of TR100 on tumor cell viability.

Rationale Stress exposure during adolescence contributes to developing a methamphetamine (METH) use disorder. However, most of the studies investigating addiction-related behaviours include only male rodents, despite METH addiction rates being higher in females. Furthermore, animal studies investigating the effects of stress on methamphetamine addiction have used only basic self-administration models which may not be sensitive to the effects of stress. Objectives This project explored whether adolescent isolation stress exposure increases the incidence of four key addiction-related behaviours in female rats. Methods Thirty-two female rat pups were caged in groups of four or individually during adolescence from postnatal (PND) day 22, with the latter being re-socialised in groups of four on PND 43. In adulthood, rats were tested for addiction-like behaviours in a METH self-administration paradigm modelling motivation to take METH, persistence in drug-seeking behaviour when METH was not available, resistance to extinction, and propensity to reinstate after a period of withdrawal. Results Adolescent social isolation resulted in lower METH intake during acquisition; however, the paradigm modelling drug-seeking when the drug was unavailable engendered intermittent METH bingeing in all rats, abolishing the group differences in intake during this phase. Adolescent social isolation also accelerated extinction of non-reinforced lever pressing, and increased stress-primed reinstatement, compared to the group-housed rats. Conclusions Adolescent social isolation stress alters various methamphetamine addiction-like behaviours in female rats.

Cyclic peptides with esters but not N-methyl amides are the smallest known alpha helices in water and can enter cells.

There is high potential for ecosystem restoration across tropical savannah-dominated regions, but the benefits that could be gained from this restoration are rarely assessed. This study focuses on the Brazilian Cerrado, a highly species-rich savannah-dominated region, as an exemplar to review potential restoration benefits using three metrics: net biomass gains, plant species richness and ability to connect restored and native vegetation. Localized estimates of the most appropriate restoration vegetation type (grassland, savannah, woodland/forest) for pasturelands are produced. Carbon sequestration potential is significant for savannah and woodland/forest restoration in the seasonally dry tropics (net biomass gains of 58.2 ± 37.7 and 130.0 ± 69.4 Mg ha −1 ). Modelled restoration species richness gains were highest in the central and south-east of the Cerrado for savannahs and grasslands, and in the west and north-west for woodlands/forests. The potential to initiate restoration projects across the whole of the Cerrado is high and four hotspot areas are identified. We demonstrate that landscape restoration across all vegetation types within heterogeneous tropical savannah-dominated regions can maximize biodiversity and carbon gains. However, conservation of existing vegetation is essential to minimizing the cost and improving the chances of restoration success. This article is part of the theme issue ‘Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration’.

N- or C-methylation in natural and synthetic cyclic peptides can increase membrane permeability, but it remains unclear why this happens in some cases but not others. Here we compare three-dimensional structures for cyclic peptides from six families, including isomers differing only in the location of an N- or Cα-methyl substituent. We show that a single methyl group only increases membrane permeability when it connects or expands hydrophobic surface patches. Positional isomers, with the same molecular weight, hydrogen bond donors/acceptors, rotatable bonds, calculated LogP, topological polar surface area, and total hydrophobic surface area, can have different membrane permeabilities that correlate with the size of the largest continuous hydrophobic surface patch. These results illuminate a key local molecular determinant of membrane permeability.

Millimeter-wave lens antennas will be essential for future wireless access. Conventionally, they increase the gain in the boresight direction only. In this article, cascaded Fresnel zone plate lenses are combined with a phased array to increase the gain at wide steering angles of ±52°. The side lenses are tilted to align with the maximum steering angle and cascaded to increase the focusing gain. The inner lenses increase the gain by 2.45 dB at boresight, and by 3.19 dB at the maximum steering angle. When the side lenses are repositioned, the simulated focusing gain increases to 4.69 dB. Asymmetric amplitude distributions are proposed to prevent the main lobe from splitting. An eight-element seven-lens prototype operating at 28 GHz achieved a gain from 12.96 to 15.35 dBi with a bandwidth of at least 1.3 GHz for all measured beam directions. The maximum measured azimuthal beamwidth was 27°. A design procedure and a theoretical analysis of diffraction through the lenses are provided. By increasing the SNR, this beamforming antenna could improve the coverage of three-sector 5G microcell base stations, and support gigabit wireless links for vehicular, rail, and satellite communications.

In its 33 years, ADDR has published regularly on the po5tential of oral delivery of biologics especially peptides and proteins. In the intervening period, analysis of the preclinical and clinical trial failures of many purported platform technologies has led to reflection on the true status of the field and reigning in of expectations. Oral formulations of semaglutide, octreotide, and salmon calcitonin have completed Phase III trials, with oral semaglutide being approved by the FDA in 2019. The progress made with oral peptide formulations based on traditional permeation enhancers is against a background of low and variable oral bioavailability values of ~1%, leading to a current perception that only potent peptides with a viable cost of synthesis can be realistically considered. Desirable features of candidates should include a large therapeutic index, some stability in the GI tract, a long elimination half-life, and a relatively low clearance rate. Administration in nanoparticle formats have largely disappointed, with few prototypes reaching clinical trials: insufficient particle loading, lack of controlled release, low epithelial particle uptake, and lack of scalable synthesis being the main reasons for discontinuation. Disruptive technologies based on engineered devices promise improvements, but scale-up and toxicology aspects are issues to address. In parallel, medicinal chemists are synthesizing stable hydrophobic macrocyclic candidate peptides of lower molecular weight and with potential for greater oral bioavailability than linear peptides, but perhaps without the same requirement for elaborate drug delivery systems. In summary, while there have been advances in understanding the limitations of peptides for oral delivery, low membrane permeability, metabolism, and high clearance rates continue to hamper progress.

The introduction of an amide bond linking side chains of the first and fifth amino acids forms a cyclic pentapeptide that optimally stabilizes the smallest known α-helix in water. The origin of the stabilization is unclear. The observed dependence of α-helicity on the solvent and cyclization linker led us to discover a novel long-range n to π* interaction between a main-chain amide oxygen and a uniquely positioned carbonyl group in the linker of cyclic pentapeptides. CD and NMR spectra, NMR and X-ray structures, modelling, and MD simulations reveal that this first example of a synthetically incorporated long-range n to π* CO⋅⋅⋅Cγ =Ο interaction uniquely enforces an almost perfect and remarkably stable peptide α-helix in water but not in DMSO. This unusual interaction with a covalent amide bond outside the helical backbone suggests new approaches to synthetically stabilize peptide structures in water.

Description, Novel macrocyclic peptides are found that bind and modulate the function of the retromer membrane trafficking complex., The retromer complex (Vps35-Vps26-Vps29) is essential for endosomal membrane trafficking and signaling. Mutation of the retromer subunit Vps35 causes late-onset Parkinson’s disease, while viral and bacterial pathogens can hijack the complex during cellular infection. To modulate and probe its function, we have created a novel series of macrocyclic peptides that bind retromer with high affinity and specificity. Crystal structures show that most of the cyclic peptides bind to Vps29 via a Pro-Leu–containing sequence, structurally mimicking known interactors such as TBC1D5 and blocking their interaction with retromer in vitro and in cells. By contrast, macrocyclic peptide RT-L4 binds retromer at the Vps35-Vps26 interface and is a more effective molecular chaperone than reported small molecules, suggesting a new therapeutic avenue for targeting retromer. Last, tagged peptides can be used to probe the cellular localization of retromer and its functional interactions in cells, providing novel tools for studying retromer function.

Physical and chemical stabilisation mechanisms are now known to play a critical role in controlling carbon (C) storage in mineral soils, leading to suggestions that climate warming-induced C losses may be lower than previously predicted. By analysing > 9,000 soil profiles, here we show that, overall, C storage declines strongly with mean annual temperature. However, the reduction in C storage with temperature was more than three times greater in coarse-textured soils, with limited capacities for stabilising organic matter, than in fine-textured soils with greater stabilisation capacities. This pattern was observed independently in cool and warm regions, and after accounting for potentially confounding factors (plant productivity, precipitation, aridity, cation exchange capacity, and pH). The results could not, however, be represented by an established Earth system model (ESM). We conclude that warming will promote substantial soil C losses, but ESMs may not be predicting these losses accurately or which stocks are most vulnerable., The extent to which temperature controls soil carbon storage remains highly uncertain. Here, the authors show that, globally, soil carbon stocks decline strongly with temperature, but the effect is much greater in coarse-textured soils with limited organic matter stabilisation capacities, than in fine-textured soils.

Protein–protein interactions involve hotspots as small as 4 sequential amino acids. Corresponding tetrapeptides have no structure in water. Here we report linking side chains of amino acids X and Z to form 24 cyclic tetrapeptides, cyclo-[XAAZ]-NH2, and stabilise 14–18 membered rings that mimic different kinds of non-regular secondary structures found in protein hotspots. 2D NMR spectra allowed determination of 3D structures for 14 cyclic tetrapeptides in water. Five formed two (i, i + 3) hydrogen bonds and a beta/gamma (6, 7) or beta (9, 19, 20) turn; eight formed one (i, i + 4) hydrogen bond and twisted into a non-helical (13, 18, 21, 22, 24) or helical (5, 17, 23) alpha turn; one was less structured (15). A beta or gamma turn was favoured for Z = Dab, Orn or Glu due to a χ1 gauche (+) rotamer, while an alpha turn was favoured for Z = Dap (but not X = Dap) due to a gauche (−) rotamer. Surprisingly, an unstructured peptide ARLARLARL could be twisted into a helix when either a helical or non-helical alpha turn (5, 13, 17, 18, 21–24) with Z = Dap was attached to the N-terminus. These structural models provide insights into stability for different turns and twists corresponding to non-regular folds in protein hotspots.

Agroforestry is an integration of trees in cropland or grassland and is discussed, within Germany and the EU, as a potential “Green Solution” for agriculture. Agroforestry alters the microclimate, productivity, biodiversity, and nutrient and water usage – as compared to standard agricultural practise. A potentially key benefit is the higher carbon sequestration of agroforestry, relative to monoculture systems, which could provide an interesting option for mitigating climate change, while still providing valuable arable land. Net ecosystem exchange studies of CO2 (NEE) of agroforestry systems are rare, in comparison to the extensive studies of NEE of agricultural systems (croplands and grasslands). Therefore, the current study, as part of the SIGNAL (sustainable intensification of agriculture through agroforestry) project, investigates the NEE of agroforestry compared to that of monoculture agriculture.At five locations across Germany, paired flux measurements above agroforestry and monoculture agronomy are performed using innovative low-cost CO2 eddy covariance sensors (slow response Vaisala GMP343 IRGA, with custom made housing). During the summer of 2020 simultaneous measurements of the low-cost setup and a LI-COR 7200 are performed, above grassland at 3.5 m and adjacent agroforestry grassland at 10 m measurements height.The low-cost eddy covariance system is able to capture the turbulent (diurnal) CO2 flux dynamics and the response to management activities. After spectral corrections and applying quality control, the low-cost system at the agroforestry site (slope = 0.92, R2 = 0.88) performs better than the low-cost system at the grassland site (slope = 0.67, R2 = 0.80), when compared to the LI-COR measurements. This is probably due to the difference in turbulence caused by different surface roughness and measurement height. The preliminary cumulative carbon flux during the four-month measurement campaign shows a significant difference between the grassland (source of (+) 16-38 gC/m2) and agroforestry grassland (sink of (-) 148-164 gC/m2), in favour of agroforestry. By applying post processing software, we aim to further optimize the frequency corrections for the low-cost system. In the future the obtained post processing scheme will be applied to the other low-cost eddy covariance systems within the project.

Semi-invariant natural killer T (iNKT) cells are self-reactive lymphocytes, yet how this lineage attains self-tolerance remains unknown. iNKT cells constitutively express high levels ofNr4a1-encoded Nur77, a transcription factor that integrates signal strength downstream of the T cell receptor (TCR) within activated thymocytes and peripheral T cells. The function of Nur77 in iNKT cells is unknown. Here we report that sustained Nur77 overexpression (Nur77tg) in mouse thymocytes abrogates iNKT cell development. Introgression of a rearrangedVα14-Jα18TCR-α chain gene into the Nur77tg(Nur77tg;Vα14tg) mouse rescued iNKT cell development up to the early precursor stage, stage 0. iNKT cells in bone marrow chimeras that reconstituted thymic cellularity developed beyond stage 0 precursors and yielded IL-4–producing NKT2 cell subset but not IFN-γ–producing NKT1 cell subset. Nonetheless, the developing thymic iNKT cells that emerged in these chimeras expressed the exhaustion marker PD1 and responded poorly to a strong glycolipid agonist. Thus, Nur77 integrates signals emanating from the TCR to control thymic iNKT cell tolerance induction, terminal differentiation, and effector functions.

The Retromer complex (Vps35-Vps26-Vps29) is essential for endosomal membrane trafficking and signalling. Mutations in Retromer cause late-onset Parkinson’s disease, while viral and bacterial pathogens can hijack the complex during cellular infection. To modulate and probe its function we have created a novel series of macrocyclic peptides that bind Retromer with high affinity and specificity. Crystal structures show the majority of cyclic peptides bind to Vps29 via a Pro-Leu-containing sequence, structurally mimicking known interactors such as TBC1D5, and blocking their interaction with Retromer in vitro and in cells. By contrast, macrocyclic peptide RT-L4 binds Retromer at the Vps35-Vps26 interface and is a more effective molecular chaperone than reported small molecules, suggesting a new therapeutic avenue for targeting Retromer. Finally, tagged peptides can be used to probe the cellular localisation of Retromer and its functional interactions in cells, providing novel tools for studying Retromer function.

Funding: The research was carried out as part of a project funded by the Malaysian Palm Oil Board (MPOB). L. K. K and E. R. are both employees of MPOB. The research was carried out with the support of Sarawak Oil Palm Berhard (SOPB) on whose land the research project was based. Need for regional economic development and global demand for agro‐industrial commodities has resulted in large‐scale conversion of forested landscapes to industrial agriculture across South East Asia. However, net emissions of CO2 from tropical peatland conversions may be significant and remain poorly quantified, resulting in controversy around the magnitude of carbon release following conversion. Here we present long term, whole ecosystem monitoring of carbon exchange from two oil palm plantations on converted tropical peat swamp forest. Our sites compare a newly converted oil palm plantation (OPnew) to a mature oil palm plantation (OPmature) and combine them in the context of existing emission factors. Mean annual net emission (NEE) of CO2 measured at OPnew during the conversion period (137.8 Mg CO2 ha‐1 yr ‐1) were an order of magnitude lower during the measurement period at OPmature (17.5 Mg CO2 ha‐1 yr‐1). However, mean water table depth (WTD) was shallower (0.26 m) than a typical drainage target of 0.6 m suggesting our emissions may be a conservative estimate for mature plantations, mean WTD at OPnew was more typical at 0.54 m. Reductions in net emissions were primarily driven by increasing biomass accumulation into highly productive palms. Further analysis suggested annual peat carbon losses of 24.9 Mg CO2‐C ha‐1 yr‐1 over the first 6 years, lower than previous estimates for this early period from subsidence studies, losses reduced to 12.8 Mg CO2‐C ha‐1 yr‐1 in the later, mature phase. Despite reductions in NEE and carbon loss over time, the system remained a large net source of carbon to the atmosphere after 12 years with the remaining 8 years of a typical plantation’s rotation unlikely to recoup losses. These results emphasise the need for effective protection of tropical peatlands globally and strengthening of legislative enforcement where moratoria on peatland conversion already exist. Publisher PDF

Potential land–climate feedbacks in subarctic regions, where rapid warming is driving forest expansion into the tundra, may be mediated by differences in transpiration of different plant functional types. Here, we assess the environmental controls of overstorey transpiration and its relevance for ecosystem evapotranspiration in subarctic deciduous woodlands. We measured overstorey transpiration of mountain birch canopies and ecosystem evapotranspiration in two locations in northern Fennoscandia, having dense (Abisko) and sparse (Kevo) overstories. For Kevo, we also upscale chamber‐measured understorey evapotranspiration from shrubs and lichen using a detailed land cover map. Subdaily evaporative fluxes were not affected by soil moisture and showed similar controls by vapour pressure deficit and radiation across sites. At the daily timescale, increases in evaporative demand led to proportionally higher contributions of overstorey transpiration to ecosystem evapotranspiration. For the entire growing season, the overstorey transpired 33% of ecosystem evapotranspiration in Abisko and only 16% in Kevo. At this latter site, the understorey had a higher leaf area index and contributed more to ecosystem evapotranspiration compared with the overstorey birch canopy. In Abisko, growing season evapotranspiration was 27% higher than precipitation, consistent with a gradual soil moisture depletion over the summer. Our results show that overstorey canopy transpiration in subarctic deciduous woodlands is not the dominant evaporative flux. However, given the observed environmental sensitivity of evapotranspiration components, the role of deciduous trees in driving ecosystem evapotranspiration may increase with the predicted increases in tree cover and evaporative demand across subarctic regions.

Agroforestry is a combination of monoculture agriculture and trees. Studies of net ecosystem exchange of CO2 (NEE) of agroforestry systems are rare, in comparison to the extensive studies of NEE of agricultural systems (croplands and grasslands). Agroforestry has been shown to alter the microclimate, productivity, and nutrient and water usage – as compared to standard agricultural practise. The, potentially, higher carbon sequestration of agroforestry, relative to monoculture systems, provides an interesting option for mitigating climate change, highlighting the need for improved study of agroforestry systems. The current study, as part of the SIGNAL (sustainable intensification of agriculture through agroforestry) project, investigates NEE of agroforestry compared to that of monoculture agriculture. The study employs paired comparisons of flux measurements above agroforestry and monoculture agronomy, replicated at five locations across Germany. Fluxes are measured, using innovative low-cost CO2 eddy covariance sensors (slow response Vaisala GMP343 IRGA with custom made housing), which have been successfully used in a study over grassland. Continuous data series from mid-summer until winter 2019 show that both systems acted as a sink with comparable fluxes during summer. The diurnal CO2 cycle and the response to management activities are distinguishable and in autumn preliminary results suggest a small difference in fluxes between the two systems. The low-cost eddy covariance system is able to capture the turbulence and to measure the CO2 flux over the agroforestry and monoculture agricultural system. We aim to further improve the quality of the CO2 fluxes, by adapting post-processing software to better estimate the difference in carbon uptake between the agroforestry and monoculture systems.