Search results for "Transporter"
showing 10 items of 676 documents
Temporal aspects of copper homeostasis and its crosstalk with hormones
2015
To cope with the dual nature of copper as being essential and toxic for cells, plants temporarily adapt the expression of copper homeostasis components to assure its delivery to cuproproteins while avoiding the interference of potential oxidative damage derived from both copper uptake and photosynthetic reactions during light hours. The circadian clock participates in the temporal organization of coordination of plant nutrition adapting metabolic responses to the daily oscillations. This timely control improves plant fitness and reproduction and holds biotechnological potential to drive increased crop yields. Hormonal pathways, including those of abscisic acid, gibberellins, ethylene, auxin…
Comparison of global responses to mild deficiency and excess copper levels in Arabidopsis seedlings
2013
[EN] Copper is an essential micronutrient in higher plants, but it is toxic in excess. The fine adjustments required to fit copper nutritional demands for optimal growth are illustrated by the diverse, severe symptoms resulting from copper deficiency and excess. Here, a differential transcriptomic analysis was done between Arabidopsis thaliana plants suffering from mild copper deficiency and those with a slight copper excess. The effects on the genes encoding cuproproteins or copper homeostasis factors were included in a CuAt database, which was organised to collect additional information and connections to other databases. The categories overrepresented under copper deficiency and copper e…
Biological activities of Schottenol and Spinasterol, two natural phytosterols present in argan oil and in cactus pear seed oil, on murine miroglial B…
2014
International audience; The objective of this study was to evaluate the biological activities of the major phytosterols present in argan oil (AO) and in cactus seed oil (CSO) in BV2 microglial cells. Accordingly, we first determined the sterol composition of AO and CSO, showing the presence of Schottenol and Spinasterol as major sterols in AO. While in CSO, in addition to these two sterols, we found mainly another sterol, the Sitosterol. The chemical synthesis of Schottenol and Spinasterol was performed. Our results showed that these two phytosterols, as well as sterol extracts from AO or CSO, are not toxic to microglial BV2 cells. However, treatments by these phytosterols impact the mitoch…
Protein Kinase C Activation Promotes the Internalization of the Human Cationic Amino Acid Transporter hCAT-1
2004
The human cationic amino acid transporter hCAT-1 is almost ubiquitously expressed and probably the most important entity for supplying cells with extracellular arginine, lysine, and ornithine. We have previously shown that hCAT-1-mediated transport is decreased after protein kinase C (PKC) activation by phorbol 12-myristate 13-acetate (PMA) (Graf, P., Forstermann, U., and Closs, E. I. (2001) Br. J. Pharmacol. 132, 1193-1200). In the present study, we examined the mechanism of this down-regulation. In both Xenopus laevis oocytes and U373MG glioblastoma cells, PMA treatment promoted the internalization of hCAT-1 (fused to the enhanced green fluorescence protein (EGFP)) as visualized by fluore…
Voltage dependence of L-arginine transport by hCAT-2A and hCAT-2B expressed in oocytes from Xenopus laevis.
2000
Membrane potential and currents were investigated with the two-electrode voltage-clamp technique in Xenopus laevisoocytes expressing hCAT-2A or hCAT-2B, the splice variants of the human cationic amino acid transporter hCAT-2. Both hCAT-2A- and hCAT-2B-expressing oocytes exhibited a negative extracellularl-arginine concentration ([l-Arg]o)-sensitive membrane potential, additive to the K+diffusion potential, when cells were incubated in Leibovitz medium (containing 1.45 mM l-Arg and 0.25 mM l-lysine). The two carrier proteins produced inward and outward currents, which were dependent on the l-Arg gradient and membrane potential. Ion substitution experiments showed that the hCAT-induced curren…
Polyamines Impair Immunity to Helicobacter pylori by Inhibiting L-Arginine Uptake Required for Nitric Oxide Production
2010
International audience; BACKGROUND & AIMS: Helicobacter pylori-induced immune responses fail to eradicate the bacterium. Nitric oxide (NO) can kill H pylori. However, translation of inducible NO synthase (iNOS) and NO generation by H pylori-stimulated macrophages is inhibited by the polyamine spermine derived from ornithine decarboxylase (ODC), and is dependent on availability of the iNOS substrate L-arginine (L-Arg). We determined if spermine inhibits iNOS-mediated immunity by reducing L-Arg uptake into macrophages. METHODS: Levels of the inducible cationic amino acid transporter (CAT) 2, ODC, and iNOS were measured in macrophages and H pylori gastritis tissues. L-Arg uptake, iNOS expressi…
Functional characterization of ORCTL2--an organic cation transporter expressed in the renal proximal tubules.
1998
AbstractChromosome 11p15.5 harbors a gene or genes involved in Beckwith-Wiedemann syndrome that confer(s) susceptibility to Wilms' tumor, rhabdomyosarcoma, and hepatoblastoma. We have previously identified a transcript at 11p15.5 which encodes a putative membrane transport protein, designated organic cation transporter-like 2 (ORCTL2), that shares homology with tetracycline resistance proteins and bacterial multidrug resistance proteins. In this report, we have investigated the transport properties of ORCTL2 and show that this protein can confer resistance to chloroquine and quinidine when overexpressed in bacteria. Immunohistochemistry analyses performed with anti-ORCTL2 polyc.onal antibod…
Identification of Novel Anthracycline Resistance Genes and Their Inhibitors
2021
Differentially expressed genes have been previously identified by us in multidrug-resistant tumor cells mainly resistant to doxorubicin. In the present study, we exemplarily focused on some of these genes to investigate their causative relationship with drug resistance. HMOX1, NEIL2, and PRKCA were overexpressed by lentiviral-plasmid-based transfection of HEK293 cells. An in silico drug repurposing approach was applied using virtual screening and molecular docking of FDA-approved drugs to identify inhibitors of these new drug-resistant genes. Overexpression of the selected genes conferred resistance to doxorubicin and daunorubicin but not to vincristine, docetaxel, and cisplatin, indicating…
Binge-like alcohol exposure in adolescence: behavioural, neuroendocrine and molecular evidence of abnormal neuroplasticity … and return
2021
Binge alcohol consumption among adolescents affects the developing neural networks underpinning reward and stress processing in the nucleus accumbens (NAc). This study explores in rats the long-lasting effects of early intermittent exposure to intoxicating alcohol levels at adolescence, on: (1) the response to natural positive stimuli and inescapable stress