Valeria Vasta

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In 32PO4-labeled adipocytes, isoproterenol (ISO) or physiologically relevant concentrations of insulin rapidly increased phosphorylation of a particulate 135-kDa protein which has been identified as a cGMP-inhibited "low Km" cAMP phosphodiesterase (CGI-PDE) by several criteria, including selective immunoprecipitation with anti-CGI-PDE IgG (Degerman, E.,(More)
The present study showed that sphingosine 1-phosphate (SPP) induced rapid stimulation of phospholipase D (PLD) in skeletal muscle C2C12 cells. The effect was receptor-mediated since it was fully inhibited by pertussis toxin. All known SPP-specific receptors, Edg-1, Edg-3 and AGR16/H218, resulted to be expressed in C2C12 myoblasts, although at a different(More)
Incubation of intact rat fat cells with maximally effective concentrations of insulin (1 nM, 12 min) or isoprenaline (300 nM, 3 min) increased particulate cGMP- and cilostamide-inhibited, low-Km cAMP phosphodiesterase (cAMP-PDE) activity by about 50% and 100%, respectively. In 32P-labeled cells, these agents induced serine 32P-phosphorylation of a 135-kDa(More)
Glutamine is actively metabolized in human platelets, representing a preferential mitochondrial oxidative substrate in these cells. The primary importance of this metabolic route of glutamine is further confirmed here by the observation that platelet glutaminase activity is entirely represented by the phosphate dependent glutaminase or glutaminase I, most(More)
The present study demonstrates that human platelets possess a specific L-arginine transport system able to provide adequate amounts of L-arginine for endogenous nitric oxide production. L-arginine uptake takes place through a saturable high affinity carrier-mediated Na(+)-independent process which is significantly inhibited by L-ornithine, L-lysine and N(More)
Phospholipase D (PLD) has been implicated as a crucial signaling enzyme in secretory pathways. Two 20-kDa guanine nucleotide-binding proteins, Rho and ADP-ribosylation factor (ARF), are involved in the regulation of secretion and can activate PLD in vitro. We investigated in intact (human adenocarcinoma A549 cells) the role of RhoA and ARF in activation of(More)
Understanding molecular mechanisms involved in melanoma resistance to drugs is a big challenge. Experimental evidences suggested a correlation between mutational status in B-RAF and melanoma cell susceptibility to drugs, such as paclitaxel, doxorubicin and temozolomide, which generate an accumulation of hydrogen peroxide (H2O2) in the cells. We investigated(More)
Exogenous glutamine was metabolized by platelets to glutamate, aspartate, and CO2; whereas no lactate was formed. The amount of aspartate and CO2 produced from glutamine was reduced by the presence of glucose. On the other hand the rate of oxidation of glucose was reduced by the presence of glutamine. The potential energetic value of glutamine was lower(More)
The involvement of the glycosylphosphatidylinositol/inositol phosphoglycan (gly-PtdIns/IPG) system in the stimulation of macromolecular syntheses in human fibroblasts has been investigated. The study demonstrates that an insulin sensitive gly-PtdIns/IPG system is present in human fibroblasts, that IPG can significantly stimulate DNA, RNA, and protein(More)
Upon hydrolysis of membrane glycosyl-phosphatidylinositol (gly-PtdIns), an inositol phosphoglycan (IPG) is generated, responsible for multiple biological activities and recently proposed as mediator of the action of a variety of hormones and growth factors. The present study shows that IPG is able to significantly stimulate platelet glycolysis, which(More)