Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.16 (calcineurin)
 17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Okadaic acid, a potent inhibitor of protein phosphatases 1 and 2A, profoundly influenced the activity of the NADPH oxidase of human neutrophils. It strongly inhibited stimulation of superoxide generation by phorbol 12-myristate 13-acetate (PMA) and impaired translocation of protein kinase activity and of the two cytosolic components p47-phox and p67-phox to the plasma membrane. The increase in the phosphorylation of the cytochrome b-245 subunits p22-phox and gp91-phox after stimulation was also blocked. Inhibition of activity was associated with a decrease in cytosolic free Ca2+ and was reversed by the Ca2+ ionophore A23187, which also restored protein translocation and phosphorylation of the cytochrome. This effect of A23187 was itself blocked by preincubation with cyclosporin A, suggesting that calcineurin might be involved in the re-activation process. In contrast with PMA, the response to the bacterial peptide fMet-Leu-Phe was greatly prolonged after an initial decrease in the rate of onset of NADPH oxidase activity.
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PMID:Okadaic acid produces changes in phosphorylation and translocation of proteins and in intracellular calcium in human neutrophils. Relationship with the activation of the NADPH oxidase by different stimuli. 141 26

Ceramide, a product arising from sphingomyelinase activity, has been shown to act as an intracellular second messenger in effecting growth inhibition, cellular differentiation, and apoptosis. In the present study, the relative effects of cell-permeable ceramides, N-acetylsphingosine (C2-ceramide) and N-hexanoylsphingosine (C6-ceramide), on neutrophil responses were measured. When cells were activated with fMet-Leu-Phe, C2-ceramide both potentiated (< 1 microM) and inhibited (> 1 microM) superoxide generation. C2- and C6-ceramide inhibited phorbol ester-induced superoxide release from neutrophils at IC50 values of 5 and 120 microM, respectively. C2-ceramide had no effect on semipurified protein kinase C activity. Neither ceramide affected significantly the general level of phosphorylated proteins in phorbol ester-treated cells. C2-ceramide (1-20 microM) alone did not change cytosolic free Ca2+ levels but inhibited Ca2+ and Mn2+ influx in fMet-Leu-Phe-activated neutrophils. In contrast, sphingosine enhanced Ca2+ entry; thus, ceramide conversion to sphingosine was not significant. Unlike C2-ceramide, C2-dihydroceramide failed to block superoxide generation or Ca2+ influx. Preincubation of cells with 10 nM okadaic acid reversed slightly the effects of C2-ceramide. Calyculin A, tautomycin, and much higher concentrations of okadaic acid inhibited agonist-induced Ca2+ influx. We postulate that C2-ceramide may inhibit neutrophil superoxide release by activation of type 2A protein phosphatases. Results suggest that protein phosphatase type 1 up-regulates Ca2+ entry, whereas type 2A (or a ceramide-activated subtype) forestalls Ca2+ entry by inactivating a calcium influx factor.
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PMID:N-acetylsphingosine (C2-ceramide) inhibited neutrophil superoxide formation and calcium influx. 785 86

In this report, we show that the p14 subunit of calcium-binding myeloid protein complex (p8,14) is phosphorylated in human neutrophils stimulated with either fMet-Leu-Phe, phorbol myristate acetate, or a calcium ionophore. Trifluoperazine, a calmodulin antagonist, caused hyperphosphorylation of p14 in intact resting neutrophils. Preincubation of resting cells with 10-20 nM calyculin A, a potent protein phosphatase inhibitor, also caused enhanced labeling of p14, which was further progressively increased on stimulation with fMLP. Thus, the phosphorylation level of p14 in resting as well as in stimulated neutrophils appears to be controlled by an active protein phosphatase. The phosphorylation of p14 by a chemoattractant and by a phorbol ester is a novel finding supporting the current belief that p8,14 myeloid protein may play an important role in the metabolism of myeloid cells.
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PMID:Calcium-binding myeloid protein (P8,14) is phosphorylated in fMet-Leu-Phe-stimulated neutrophils. 836 May 91

This paper is addressed to study how PKC-mediated effects and phosphatidic acid interact together in activation of NADPH-oxidase in formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe) stimulated neutrophils as detected by luminol chemiluminescence. The early luminescence response in fMet-Leu-Phe-stimulated cells (up to 5 min after stimulation) depends mainly on reactive oxygen species generated extracellularly, whereas all later events are caused by oxidation of luminol inside the cells. The two protein phosphatase inhibitors, okadaic acid and calyculin A, dramatically increased the late luminescence of cells. This enhancement was totally inhibited by the phospholipase D modulator butanol, while the protein kinase C (PKC) inhibitor bisindolylmaleimide I was insensitive. The early luminescence response of the cells was slightly inhibited by both protein phosphatase inhibitors and depended on protein kinase C as well as on phospholipase D activities. Propranolol, an inhibitor of phosphatidate phosphohydrolase, enhanced all parts of luminescence response of fMet-Leu-Phe-stimulated neutrophils at concentrations up to 2.5 x 10(-5) mol/L. While the late luminescence response of propranolol-treated cells was not inhibited by the PKC inhibitor bisindolylmaleimide I, the first response depended on protein kinase C. The inhibitor of diacylglycerol kinase R59949 enhanced the luminescence signal only during the first 4 min in fMet-Leu-Phe-stimulated cells. Only diacylglycerols derived from phospholipase C, such as 1-stearoyl-2-arachidonoyl-sn-glycerol, were able to initiate an oxidative burst in cells. Saturated diacylglycerols (e.g. 1,2-dipalmitoyl-sn-glycerol or 1,2-distearoyl-sn-glycerol) did not yield any luminol chemiluminescence, although they were incorporated into the plasma membrane, as evidenced by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Our results demonstrate that phosphatidic acid produced by phospholipase D is responsible for NADPH-oxidase activity in fMet-Leu-Phe-stimulated neutrophils over the entire measuring time, whereas PKC-mediated processes are only involved during the first 5 min.
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PMID:Modulation of luminol chemiluminescence of fMet-Leu-Phe-stimulated neutrophils by affecting dephosphorylation and the metabolism of phosphatidic acid. 1042 73