Search results for "Intracellular"
showing 10 items of 821 documents
Intracellular Na+ concentration influences short-term plasticity of glutamate transporter-mediated currents in neocortical astrocytes.
2012
Fast synaptic transmission requires a rapid clearance of the released neurotransmitter from the extracellular space. Glial glutamate transporters (excitatory amino acid transporters, EAATs) strongly contribute to glutamate removal. In this work, we investigated the paired-pulse plasticity of synaptically activated, glutamate transporter-mediated currents (STCs) in cortical layer 2/3 astrocytes. STCs were elicited by local electrical stimulation in layer 4 in the presence of ionotropic glutamate (AMPA and NMDA), GABAA, and GABAB receptor antagonists. In experiments with low [Na+]i (5 mM) intrapipette solution, STCs elicited by paired-pulse stimulation demonstrated paired-pulse facilitation (…
Potassium regulates IL-1 beta processing via calcium-independent phospholipase A2.
2000
Abstract We report that potassium leakage from cells leads to activation of the Ca2+-independent phospholipase A2 (iPLA2), and the latter plays a pivotal role in regulating the cleavage of pro-IL-1β by the IL-converting enzyme caspase-1 in human monocytes. K+ efflux led to increases of cellular levels of glycerophosphocholine, an unambiguous indicator of phospholipase A2 activation. Both maturation of IL-1β and formation of glycerophosphocholine were blocked by bromoenol lactone, the specific iPLA2 inhibitor. Bromoenol lactone-dependent inhibition of IL-1β processing was not due to perturbation of the export machinery for pro-IL-1β and IL-1β or to caspase-1 suppression. Conspicuously, activ…
Depletion of alphaV integrins from osteosarcoma cells by intracellular antibody expression induces bone differentiation marker genes and suppresses g…
1999
Integrin heterodimers sharing the common alphaV subunit are receptors for adhesion glycoproteins such as vitronectin and fibronectin. They are suggested to play an essential role in cell anchoring, differentiation, and survival. Here, we describe the construction of an expression plasmid coding for an intracellular single-chain antibody against alphaV integrin subunit. Saos-2 osteosarcoma cells transfected with this DNA construct showed an approximately 70-100% decrease in the cell surface expression of alphaVbeta3 and alphaVbeta5 integrins as shown by flow cytometry. Intracellular antibody expression had no effect on the mRNA levels of alphaV integrin. Pulse chase experiments of metabolica…
Role of Neutral Amino Acid Transport and Protein Breakdown for Substrate Supply of Nitric Oxide Synthase in Human Endothelial Cells
2003
Endothelial dysfunction is often associated with a relative substrate deficiency of the endothelial nitric oxide synthase (eNOS) in spite of apparently high intracellular arginine concentrations. For a better understanding of the underlying pathophysiological mechanisms, we aimed to characterize the intracellular arginine sources of eNOS. Our previous studies in human endothelial EA.hy926 cells suggested the existence of two arginine pools: pool I can be depleted by extracellular lysine, whereas pool II is not freely exchangeable with the extracellular space, but accessible to eNOS. In this study, we demonstrate that the eNOS accessible pool II is also present in human umbilical vein endoth…
Flow-cytometric screening for the modulation of receptor-mediated endocytosis in human dendritic cells: implications for the development of an in vit…
1997
The aim of this study was to explore the usefulness of human blood dendritic cells (DC) in the development of an in vitro model for predictive testing of contact sensitizers. A method was established to monitor the influence of chemicals on the intracellular targeting of antibody-crosslinked MHC class II molecules after their uptake by human DC. Using a three-colour flow-cytometric technique, freshly prepared DC were distinguished from other MHC class II-bearing cell types such as B-cells and monocytes in unseparated mononuclear cell suspensions of healthy volunteers. The assay is based on the pH-sensitivity of internalized fluorescein-coupled MHC class II specific antibodies. Quenching of …
Modulation of NMDA receptor function by cyclic AMP in cerebellar neurones in culture
2004
The signal transduction pathways involved in NMDA receptor modulation by other receptors remain unclear. cAMP could be involved in this modulation. The aim of this work was to analyse the contribution of cAMP to NMDA receptor modulation in cerebellar neurones in culture. Forskolin increases cAMP and results in increased intracellular calcium and cGMP that are prevented by blocking NMDA receptors. Similar effects were induced by two cAMP analogues, indicating that cAMP leads to NMDA receptor activation. It has been reported that phosphorylation of Ser897 of the NR1 subunit of NMDA receptors by cAMP-dependent protein kinase (PKA) activates the receptors. Forskolin increases Ser897 phosphoryla…
Influence of calcium on the effects of okadaic acid and its interaction with caffeine and theophylline in rat myometrium.
1994
The effects of okadaic acid (OA), a monocarboxylic acid produced by marine dinoflagellates belonging to the genera Dinophysis and Prorocentrum, and their interactions with theophylline and caffeine were studied on the rat-isolated uterus in a calcium-containing medium and a calcium-free medium in the presence of 10−3 M EGTA. Okadaic acid (5 × 10−6 to 5 × 10−5 M) induced a concentration-dependent contraction of the rat-isolated uterus corresponding, with 5 × 10−5M, to 142.3±6.1% (n = 7) of the contraction induced by oxytocin 10−6 M. The time to peak tension was inversely proportional to the maximum effect produced. The contraction was not sustained and was followed by a concentration-depende…
Interaction of antibodies to proteinase 3 (classic anti-neutrophil cytoplasmic antibody) with human renal tubular epithelial cells: impact on signali…
2002
Abstract Among the anti-neutrophil cytoplasmic Abs (ANCA), those targeting proteinase 3 (PR3) have a high sensitivity and specificity for Wegener’s granulomatosis (WG). A pathogenetic role for these autoantibodies has been proposed due to their capacity of activating neutrophils in vitro. Recently, PR3 was also detected in human renal tubular epithelial cells (TEC). In the present study, the effect of murine monoclonal anti-PR3 Abs (anti-PR3) and purified c-ANCA targeting PR3 from WG serum on isolated human renal tubular cell signaling and inflammatory mediator release was characterized. Priming of TEC with TNF-α resulted in surface expression of PR3, as quantified in immunofluorescence stu…
Chronic exposure to ammonia induces isoform-selective alterations in the intracellular distribution and NMDA receptor-mediated translocation of prote…
2004
Hyperammonemia is responsible for most neurological alterations in patients with hepatic encephalopathy by mechanisms that remain unclear. Hyperammonemia alters phosphorylation of neuronal protein kinase C (PKC) substrates and impairs NMDA receptor-associated signal transduction. The aim of this work was to analyse the effects of hyperammonemia on the amount and intracellular distribution of PKC isoforms and on translocation of each isoform induced by NMDA receptor activation in cerebellar neurons. Chronic hyperammonemia alters differentially the intracellular distribution of PKC isoforms. The amount of all isoforms (except PKC zeta) was reduced (17-50%) in the particulate fraction. The con…
Methods, kits and means for determining intracellular interactions
2015
Methods, kits and systems for determining whether a reaction occurs between a chimeric transmembrane receptor and an intracellular interaction partner thereof within a cell.