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Oligodeoxynucleotides (ONs) are currently being tested in clinical trials as anti-viral and thrombolytic agents. Although ONs are biologically active in almost every cell line examined, these molecules are inefficiently internalized. In addition, the mechanism of ON transport to the active site in either the cytoplasm or nucleus remains ill-defined. Thus, elucidation of the mechanism of ON cellular...
The tonoplast H + -PPase was previously characterized in Acer pseudoplatanus cells (Pugin et al (1991) Plant Sci 73, 23-34; Fraichard et al (1993) Plant Physiol Biochem 31, 349-359). Tonoplast vesicles were obtained from vacuoles isolated from protoplasts of A pseudoplatanus suspension cultures and used to study kinetic effects of Mg 2+ and Ca 2+ on PPi hydrolysis...
Bovine brain sphingomyelin was separated into different molecular species using a reverse phase column. PLC δ1 was inhibited by all molecular species of sphingomyelin. The extent of this inhibition was dependent on the hydrophobicity. Based on fatty acid analysis, we conclude that the inhibition of PLC δ1 depends on the chain length and degree of unsaturation of the fatty acid moiety of SM. N-palmitoyl-D-sphingomyelin...
Annexin VI (AnxVI), a member of the annexin family of Ca 2+ - and membrane-binding proteins, has been shown to interact in vitro with adenine nucleotides. Furthermore, it has been proposed that within the AnxVI molecule a nucleotidde-binding domain exists, which is located in the C-terminal half of the protein, in the vicinity of Trp343. By comparison of exposure of tryptophan and multiple...
We have previously proposed that fluctuations in Ca 2+ levels should play an important role in bacteria as in eukaryotes in regulating cell cycle events (Norris et al., J. Theor. Biol. 134 (1998) 341-350). This proposal implied the presence of Ca 2+ uptake systems in bacteria, cell cycle mutants simultaneously defective in Ca 2+ -homeostasis, and perturbation...
We have previously proposed that fluctuations in Ca 2+ levels should play an important role in bacteria as in eukaryotes in regulating cell cycle events (Norris et al., J. Theor. Biol. 134 (1998) 341-350). This proposal implied the presence of Ca 2+ uptake systems in bacteria, cell cycle mutants simultaneously defective in Ca 2+ -homeostasis, and perturbation...
Despite groundbreaking work to identify numerous proteins and to focus attention on molecular interactions, the mechanism of calcium-triggered membrane fusion remains unresolved. A major difficulty in such research has been the many overlapping and interacting membrane trafficking steps in the secretory pathway, including those of membrane retrieval. Identifying the specific role(s) of a given protein,...
We have used carbon-fibre amperometry to examine the kinetics of individual secretory granule fusion/release events in bovine adrenal chromaffin cells. Transfection with plasmids encoding the light chains of botulinum neurotoxins (BoNTs) was used to investigate the effects of cleavage of syntaxin or SNAP-25 on exocytosis. Expression of BoNT/C1 or BoNT/E inhibited the extent of exocytosis that was...
Changes in the cytosolic Ca 2+ concentration ( Ca 2+c ) translate a variety of extracellular signals into widely diverse intracellular effects, ranging from secretion to movement, proliferation and also cell death. As regards the last one, it has long been known that large Ca 2+c increases lead cells to death. More recently, experimental evidence...
Mitochondria play a critical role in initiating both apoptotic and necrotic cell death. A major player in this process is the mitochondrial permeability transition pore (MPTP), a non-specific pore, permeant to any molecule of < 1.5 kDa, that opens in the inner mitochondrial membrane under conditions of elevated matrix Ca 2+ , especially when this is accompanied by oxidative stress...
Apoptosis is a form of programmed cell death important in the development and tissue homeostasis of multicellular organisms. Abnormalities in cell death control can lead to a variety of diseases, including cancer and degenerative disorders. Hence, the process of apoptosis is tightly regulated through multiple independent signalling pathways that are initiated either from triggering events within the...
The apparent catalytic constant (k cat ) of artichoke (Cynara scolymus L.) peroxidase (AKPC) with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) increased 130-fold in the presence of calcium ions (Ca 2+ ) but the affinity (K m ) of the enzyme for ABTS was 500 times lower than for Ca 2+ -free AKPC. AKPC is known to exhibit an equilibrium between 6-aquo...
When cells are treated with Ca 2+ and Ca 2+ -ionophore, c-Src kinase activity increases, whereas c-Yes kinase activity decreases. This opposite modulation can be reproduced in an in vitro reconstitution assay and is dependent on Ca 2+ and on soluble factors present in cell lysates. Since c-Src and c-Yes share a high degree of homology, with the exception of their N-terminal...
Cadmium is found in the environment as part of several, mainly zinc-rich, ores. It has been used in many technological applications, but biological systems generally failed to safely deal with this element. In mammalian biology, cadmium exposure jeopardizes health and mechanisms of cadmium toxicity are multifarious. Mainly because bioavailable cadmium mimics other metals that are essential to diverse...
The aim of this study was to determine in vitro whether lead has a direct cytotoxic effect on the female gamete or through its surrounding somatic cells. We had previously demonstrated that it partly accumulates in the mouse ovary and induces follicle and oocyte apoptosis. The data reported here demonstrate for the first time that low levels of Pb(NO3)2 (≤10 pM) affect oocyte meiosis in vitro. On...
The protein Bax Inhibitor-1 (BI-1) has recently emerged as a negative regulator of plant programmed cell death (PCD), but how it functions at the biochemical level remains unknown. To elucidate its regulation and mode of action, we used suspension cells of Nicotiana tabacum to study the effects of cytokinins (CKs) on the expression level of NtBI-1 via western analysis. We found that the NtBI-1 protein...
Cytosolic phospholipase A 2 α (cPLA 2 α, Group IVA phospholipase A 2 ) is a central mediator of arachidonate release from cellular phospholipids for the biosynthesis of eicosanoids. cPLA 2 α translocates to intracellular membranes including the Golgi in response to a rise in intracellular calcium level. The enzyme’s calcium-dependent phospholipid-binding C2 domain provides...
Calcium signalling is essential for most of the biological T-cell activities, including in Th2 lymphocytes, a T-cell subset that produce interleukin 4, 5 and 13 and which is involved in allergic diseases. T-cell receptor engagement induces the production of inositol trisphosphate that binds to its receptor, releasing intracellular Ca 2+ stores. STIM in the endo (sarco) plasmic reticulum (ER/SR)...
From the formation of a simple kidney in amphibian larvae, the pronephros, to the formation of the more complex mammalian kidney, the metanephros, calcium is present through numerous steps of tubulogenesis and nephron induction. Several calcium-binding proteins such as regucalcin/SMP-30 and calbindin-D28k are commonly used to label pronephric tubules and metanephric ureteral epithelium, respectively...
Isothiocyanates (ITCs) play a major role in the potential chemopreventive effect. Cruciferous vegetables are a particularly abundant source of ITCs. Methallyl ITC (MAITC) belongs to ITCs as a synthesized compound. However, the effects of MATIC have never been elucidated. The aim of this work was to investigate the anti-inflammatory effects and mechanisms of methallyl isothiocyanate (MAITC) in mast...
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