Molecular mechanism of Gαi activation by non-GPCR proteins with a Gα-Binding and Activating motif

Heterotrimeric G proteins are quintessential signalling switches activated by nucleotide exchange on Gα. Although activation is predominantly carried out by G-protein-coupled receptors (GPCRs), non-receptor guanine-nucleotide exchange factors (GEFs) have emerged as critical signalling molecules and therapeutic targets. Here we characterize the molecular mechanism of G-protein activation by a family of non-receptor GEFs containing a Gα-binding and -activating (GBA) motif. We combine NMR spectroscopy, computational modelling and biochemistry to map changes in Gα caused by binding of GBA proteins with residue-level resolution. We find that the GBA motif binds to the SwitchII/α3 cleft of Gα and induces changes in the G-1/P-loop and G-2 boxes (involved in phosphate binding), but not in the G-4/G-5 boxes (guanine binding). Our findings reveal that G-protein-binding and activation mechanisms are fundamentally different between GBA proteins and GPCRs, and that GEF-mediated perturbation of nucleotide phosphate binding is sufficient for Gα activation

Cost Effective Use of a Thiosulfinate-Enriched Allium sativum Extract in Combination with Chemotherapy in Colon Cancer

In this work, we sought to investigate the effects of a thiosulfinate-enriched garlic extract, co-administered with 5-fluorouracil (5-FU) or oxaliplatin chemotherapy, on the viability of colon cancer cells (Caco-2 and HT-29). We also addressed the economic feasibility of a new combined treatment of this thiosulfinate-enriched garlic extract, with oxaliplatin that could reduce the dosage and costs of a monotherapy. The thiosulfinate-enriched garlic extract not only enhanced the impact of 5-FU and oxaliplatin (500 µM) in decreasing Caco-2 and HT-29 viability, but also showed a higher effect than standard 5-FU and oxaliplatin chemotherapy as anti-cancer agents. These results provided evidences for the combination of lyophilized garlic extract and 5-FU or oxaliplatin as a novel chemotherapy regimen in colon cancer cells that may also reduce the clinical therapy costs.En este trabajo, buscamos investigar los efectos de un extracto de ajo enriquecido con tiosulfinato, coadministrado con quimioterapia con 5-fluorouracilo (5-FU) u oxaliplatino, sobre la viabilidad de las células de cáncer de colon (Caco-2 y HT-29). . También abordamos la viabilidad económica de un nuevo tratamiento combinado de este extracto de ajo enriquecido con tiosulfinato, con oxaliplatino que podría reducir la dosis y los costes de una monoterapia. El extracto de ajo enriquecido con tiosulfinato no solo mejoró el impacto del 5-FU y el oxaliplatino (500 µM) en la disminución de la viabilidad de Caco-2 y HT-29, sino que también mostró un efecto mayor que el 5-FU estándar y la quimioterapia con oxaliplatino como anticancerígeno agentes

Possible reasons for tolerance to mercury of lupin plants inoculated with Hg-resistant and sensitive Bradyrhizobium canariense strains

Trabajo presentado en el XV National Meeting of the Spanish Society of Nitrogen Fixation (SEFIN). IV Portuguese-Spanish Congress on Nitrogen Fixation, celebrado en León (España), del 16 al 18 de junio de 201

Possible reasons for tolerance to mercury of Lupinus albus cv. G1 inoculated with Hg-resistant and sensitive Bradyrhizobium canariense strains

Inoculation with a mercury (Hg)-resistant Bradyrhizobium canariense strain (L7AH) confers on Lupinus albus the ability to grow under high concentrations of Hg and to accumulate this heavy metal. To elucidate the mechanism/s implicated in the acquisition of this tolerance, lupins were inoculated with resistant (L7AH) and sensitive (L3) strains and fed with different Hg solutions (0–200 μM HgCl). Mercury application resulted in cellular alterations in leaves and nodules, depending on the strain inoculated. Mesophyll cell chloroplasts from L7AH-inoculated plants treated with Hg showed similar structure to those in control plants, while those of L3-inoculated plants treated with Hg showed a large increase in the number and size of starch granules. This resulted in a large increase in chloroplast and cell size which produced altered grana distribution with a totally disorganized thylakoid structure and clear signs of degradation. The preservation of the distribution and morphology of chloroplasts in L7AH-inoculated plants may be a reason why the photosynthetic efficiency remained unchanged even after treatment with 200 μM of Hg. Mercury exposure produced changes in L3-infected nodule ultrastructure, with evident signs of degradation, especially in bacteroids. However, only slight alterations of nodule morphology were noticed in L7AH-infected nodules. X-ray microanalysis showed that, while Hg was present in the nodules formed by L3, in both cortex and infected zone, in those formed by L7AH only low levels of Hg in the outermost layers of the cortex were detected. The exclusion of Hg from the infected zone together with the conservation of the symbiosome structure in nodules from L7AH-inoculated plants may explain the maintenance of nitrogenase activity.This work was supported by Junta de Comunidades de Castilla La-Mancha (POII10-0211-5015) and Ministerio de Economía y Competitividad (AGL2013-40758-R). BR-D was supported by the JCCL-M. The authors would like to thank Dr. F. Minchin for critical proof-reading of the manuscript. We thank V. Sousa-Egipsy for electron microscopy facilities

LIFE SOUNDLESS: New Generation of Eco-Friendly Asphalt with Recycled Materials

Noise pollution coming from traffic noise has become an important issue in urban areas. Road noise is one of the main sources of high-level traffic noise. Road noise depends not only on tires but on the pavement. Therefore, a study of mixture parameters should be performed to achieve good acoustic performance. Another important point which has to be taken into account is the acoustic performance durability. Gap-graded mixtures were selected for this project due to poor experiences with open-graded mixtures in terms of performance durability, where texture and clogging issues appeared a few years after paving. The LIFE SOUNDLESS project is seeking different ways to modify stone mastic asphalt mixes to improve the noise attenuation of pavements. A selection of mixes with different additives were created, where some waste materials were used. The selection of the best mixtures was done not only according to traditional mechanical parameters but also others, such as damping and dynamic stiffness. Once the best mixtures had been paved, the acoustic performances were measured several times to evaluate the performance durability. Several experimental methods like the close proximity (CPX) method and statistical pass by (SPB) method were used to check the sound generation and propagation of every pavement. The project was carried out on two roads overseen by the Junta de Andalucía in Seville (Spain). The difference between both roads was the traffic density and the average speed. The noise level has since been reduced by 3 dB and 7 dB on both sites

Characterization of a PET prototype based on monolithic detectors

We have characterized a PET prototype based on monolithic scintillator detectors. The prototype has a modular design with 8 identical detector cassettes, each housing 4 monolithic blocks. The cassettes are mounted on a gantry in 2 groups of 4 cassettes facing each other, totaling 32 detectors. Each detector block is composed of a trapezoidal LYSO:Ce scintillator glued to a pair of Hamamatsu S8550-02 APD matrices, which are read out by dedicated VATA 241 ASICs from Gamma Medica Ideas. The ASIC collects and amplifies the charge pulses from the 64 photosensors in each detector block, sums them into 8 rows and 8 column outputs and generates a trigger signal whenever the charge in a channel is above a user-defined threshold. Positioning algorithms based on supervised training neural networks are used for the detector blocks. A rotating platform with precise movement control is aligned with the system axis allowing acquisition of coincidence data along different projection angles. Using this system, Na22 point sources and a NEMA NU4-2008 image quality phantom filled with F18-FDG have been imaged and the images obtained have been characterized and compared with those from a Sedecal Argus PET/CT small-animal scanner, used as reference. Results show that the data acquisition system performs according to specifications and that PET imaging based on a large number of monolithic detector blocks is an alternative to designs based on segmented detectors

Well-Defined Star-Shaped Polyglutamates with Improved Pharmacokinetic Profiles As Excellent Candidates for Biomedical Applications

There is a need to develop new and innovative polymer carriers to be used as drug delivery systems and/or imaging agents owing to the fact that there is no universal polymeric system that can be used in the treatment of all diseases. Additionally, limitations with existing systems, such as a lack of biodegradability and biocompatibility, inevitably lead to side effects and poor patient compliance. New polymer therapeutics based on amino acids are excellent candidates for drug delivery, as they do not suffer from these limitations. This article reports on a simple yet powerful methodology for the synthesis of 3-arm star-shaped polyglutamic acid with well-defined structures, precise molecular weights (MW), and low polydispersity (<i>Đ</i> = <1.3). These were synthesized by ring-opening polymerization (ROP) of <i>N</i>-carboxyanhydrides (NCA) in a divergent method from novel multifunctional initiators. Herein, their exhaustive physicochemical characterization is presented. Furthermore, preliminary in vitro evaluation in selected cell models, and exhaustive in vivo biodistribution and pharmacokinetics, highlighted the advantages of these branched systems when compared with their linear counterparts in terms of cell uptake enhancement and prolonged plasma half-life