Highly Active Microbial Phosphoantigen Induces Rapid yet Sustained MEK/Erk- and PI-3K/Akt-Mediated Signal Transduction in Anti-Tumor Human γδ T-Cells

BACKGROUND: The unique responsiveness of Vgamma9Vdelta2 T-cells, the major gammadelta subset of human peripheral blood, to non-peptidic prenyl pyrophosphate antigens constitutes the basis of current gammadelta T-cell-based cancer immunotherapy strategies. However, the molecular mechanisms responsible for phosphoantigen-mediated activation of human gammadelta T-cells remain unclear. In particular, previous reports have described a very slow kinetics of activation of T-cell receptor (TCR)-associated signal transduction pathways by isopentenyl pyrophosphate and bromohydrin pyrophosphate, seemingly incompatible with direct binding of these antigens to the Vgamma9Vdelta2 TCR. Here we have studied the most potent natural phosphoantigen yet identified, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), produced by Eubacteria and Protozoa, and examined its gammadelta T-cell activation and anti-tumor properties. METHODOLOGY/PRINCIPAL FINDINGS: We have performed a comparative study between HMB-PP and the anti-CD3epsilon monoclonal antibody OKT3, used as a reference inducer of bona fide TCR signaling, and followed multiple cellular and molecular gammadelta T-cell activation events. We show that HMB-PP activates MEK/Erk and PI-3K/Akt pathways as rapidly as OKT3, and induces an almost identical transcriptional profile in Vgamma9(+) T-cells. Moreover, MEK/Erk and PI-3K/Akt activities are indispensable for the cellular effects of HMB-PP, including gammadelta T-cell activation, proliferation and anti-tumor cytotoxicity, which are also abolished upon antibody blockade of the Vgamma9(+) TCR Surprisingly, HMB-PP treatment does not induce down-modulation of surface TCR levels, and thereby sustains gammadelta T-cell activation upon re-stimulation. This ultimately translates in potent human gammadelta T-cell anti-tumor function both in vitro and in vivo upon transplantation of human leukemia cells into lymphopenic mice, CONCLUSIONS/SIGNIFICANCE: The development of efficient cancer immunotherapy strategies critically depends on our capacity to maximize anti-tumor effector T-cell responses. By characterizing the intracellular mechanisms of HMB-PP-mediated activation of the highly cytotoxic Vgamma9(+) T-cell subset, our data strongly support the usage of this microbial antigen in novel cancer clinical trials

Zinc homeostasis and signaling in health and diseases: Zinc signaling

The essential trace element zinc (Zn) is widely required in cellular functions, and abnormal Zn homeostasis causes a variety of health problems that include growth retardation, immunodeficiency, hypogonadism, and neuronal and sensory dysfunctions. Zn homeostasis is regulated through Zn transporters, permeable channels, and metallothioneins. Recent studies highlight Zn’s dynamic activity and its role as a signaling mediator. Zn acts as an intracellular signaling molecule, capable of communicating between cells, converting extracellular stimuli to intracellular signals, and controlling intracellular events. We have proposed that intracellular Zn signaling falls into two classes, early and late Zn signaling. This review addresses recent findings regarding Zn signaling and its role in physiological processes and pathogenesis

How insects survive the cold: molecular mechanisms - a review

Insects vary considerably in their ability to survive low temperatures. The tractability of these organisms to experimentation has lead to considerable physiology-based work investigating both the variability between species and the actual mechanisms themselves. This has highlighted a range of strategies including freeze tolerance, freeze avoidance, protective dehydration and rapid cold hardening, which are often associated with the production of specific chemicals such as antifreezes and polyol cryoprotectants. But we are still far from identifying the critical elements behind over-wintering success and how some species can regularly survive temperatures below -20°C. Molecular biology is the most recent tool to be added to the insect physiologist’s armoury. With the public availability of the genome sequence of model insects such as Drosophila and the production of custom-made molecular resources, such as EST libraries and microarrays, we are now in a position to start dissecting the molecular mechanisms behind some of these well-characterised physiological responses. This review aims to provide a state of the art snapshot of the molecular work currently being conducted into insect cold tolerance and the very interesting preliminary results from such studies, which provide great promise for the future

Neuroprotective Activity of Grape Seed and Skin Extract Against Lithium Exposure Using Proteomic Research

International audienceLithium (Li) has raised scientific concern because it represents a serious problem threatening human health. This study aimed firstly at analyzing and potentially quantifying the impact of Li and grape seed and skin extract (GSSE) separately and, secondly, describing the possible neuroprotective activity of GSSE against Li toxicity. To this end, rats were exposed for 30 days to different Li concentrations (0, 2, and 100 mg/kg bw), to GSSE (4000 mg/kg bw), and to binary mixture of Li and GSSE. Liquid chromatography (HPLC–MS/MS) analysis used for GSSE showed that 15 phenolic compounds are present in the extract. Significant modifications of proteins were detected in the brain using proteomics research after treatment. Proteins were successfully identified by a linear ion trap–Orbitrap mass spectrometer. These proteins can be roughly related to oxidative stress, glycolysis, signaling pathway, and inflammation. Additionally, proteins involved in cell junction such as myosin, spectrin, tubulin, ERM-binding phosphoprotein, and dynein were also affected by Li exposure. Dose response was detected for most expressed proteins after Li treatment. In contrast, GSSE induced the expression and/or the stabilization of some proteins changed after Li treatment in the brain showing its neuroprotective activity. These data demonstrate that proteomic analysis is a powerful tool to provide valuable insights into mechanisms of toxicity of Li in the nervous system of Wistar rats. To our knowledge, this is the first evidence of using GSSE as neuroprotective model against Li toxicity. These findings provide impetus for future investigation on GSSE against other toxic chemicals

Structural, optical and magnetic properties of Fe-doped CeO2 samples probed using X-ray photoelectron spectroscopy

The present study reports the effect of Fe-doping on the structural, optical, magnetic and electronic properties of polycrystalline CeO2 (for 5 and 10% doping concentration of Fe-cation) samples synthesized by low-temperature solid-state reaction method. Rietveld refinement of the X-ray diffraction patterns establishes fluorite-type face-centred cubic structure of the Fe-doped CeO2 samples and also confirms successful incorporation of Fe ions in the CeO2 lattice. The UV-Vis-NIR absorption spectra displays reduce band gap energy with rising fluency of Fe-ions, which confirm red shifts in the Fe-doped CeO2 samples. The electronic structure of the pure CeO2 and Fe-doped CeO2 polycrystalline samples have been investigated by X-ray photoemission spectroscopy (XPS). The XPS spectra of Ce 3d reveals the reduction of Ce4+ to Ce3+ states Fe-doped CeO2 samples, which are well supported by the Fe 2p and O 1s spectra. Pure polycrystalline CeO2 displays diamagnetic behaviour at room temperature. Interestingly, 5% Fe-doped CeO2 sample displays S-shape hysteresis loop and establishes room temperature ferromagnetism, whereas, 10% Fe-doped CeO2 sample shows weak ferromagnetic behaviour. A decrement is observed in the magnetization on increasing the doping concentration. The possible reason for ferromagnetism in the Fe-doped CeO2 samples may be incorporation of oxygen vacancies, which are further discussed using F-centre exchange mechanism and double exchange interaction. These experimental findings offer potential opportunities for spintronics and optoelectronics applications by integrating them into device structures and evaluating their performance as a function of their material properties